WO2023276585A1 - Method for producing composite particle, and composite particle - Google Patents

Method for producing composite particle, and composite particle Download PDF

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Publication number
WO2023276585A1
WO2023276585A1 PCT/JP2022/022996 JP2022022996W WO2023276585A1 WO 2023276585 A1 WO2023276585 A1 WO 2023276585A1 JP 2022022996 W JP2022022996 W JP 2022022996W WO 2023276585 A1 WO2023276585 A1 WO 2023276585A1
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cellulose
composite particles
micronized cellulose
ion
organic onium
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PCT/JP2022/022996
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French (fr)
Japanese (ja)
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佑美 大林
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凸版印刷株式会社
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/44—Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C08J3/16—Powdering or granulating by coagulating dispersions

Definitions

  • the present invention relates to a method for producing composite particles composed of micronized cellulose and core particles, and the composite particles.
  • Patent Document 1 discloses that fine cellulose fibers, that is, cellulose nanofibers (hereinafter also referred to as "CNF”) can be obtained by repeatedly mechanically treating wood cellulose with a blender or a grinder.
  • CNFs obtained by this method are described as having a minor axis diameter of 10 to 50 nm and a major axis diameter of 1 ⁇ m to 10 mm.
  • This CNF is one-fifth the weight of steel and more than five times stronger than steel, and has a huge specific surface area of 250 m 2 /g or more. ing.
  • the method of chemical treatment is not particularly limited, but a method of introducing an ionic functional group into the cellulose fiber to make it easier to refine is preferable.
  • Non-Patent Document 1 discloses a method of selectively phosphating the surface of cellulose fine fibers using phosphating. ing.
  • Patent Literature 2 discloses carboxymethylation by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a highly concentrated alkaline aqueous solution.
  • a carboxyl group may be introduced by directly reacting a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave with cellulose.
  • TEMPO 2,2,6,6-tetramethylpiperidinyl-1-oxy radical
  • Patent Document 3 The oxidation reaction using TEMPO as a catalyst (TEMPO oxidation reaction) is an environmentally friendly chemical modification that progresses in an aqueous system at normal temperature and pressure. When applied to cellulose in wood, there is no reaction inside the crystal. It does not proceed, and only alcoholic primary carbons possessed by cellulose molecular chains on the crystal surface can be selectively converted into carboxyl groups.
  • CSNF Cellulose single nanofibers
  • Wood-derived CSNF obtained from wood by TEMPO oxidation reaction is a structure having a high aspect ratio with a short axis diameter of about 3 nm and a long axis diameter of several tens of nm to several ⁇ m. has been reported to have high transparency.
  • Patent Document 4 describes that a laminated film obtained by coating and drying a CSNF dispersion has gas barrier properties.
  • Patent Document 5 describes that a dispersion in which highly refined cellulose is dispersed in an organic solvent can be obtained by surface modification in which organic onium cations are arranged as counterions of cationic finely divided cellulose.
  • Patent Document 6 describes an aqueous coating liquid containing TEMPO-oxidized CNF. It is described that this water-based coating liquid has good coatability, and that a laminate having barrier properties can be obtained by coating it on the anchor layer.
  • Patent Document 7 discloses a coating liquid containing TEMPO-oxidized CNF in which carbon fine particles are dispersed and stabilized by the influence of the entanglement and thickening properties of cellulose nanofibers with a high aspect ratio, and the charge derived from the carboxy group. ing.
  • the problem is that the solid content concentration of the obtained CNF dispersion is as low as about 0.1 to 5%.
  • the solid content concentration of the obtained CNF dispersion is as low as about 0.1 to 5%.
  • it is transported together with a large amount of solvent, which increases transportation costs and greatly affects business feasibility.
  • problems such as poor addition efficiency due to low solid content concentration and difficulty in compounding when water, which is a solvent, is not compatible with resin. be.
  • countermeasures such as refrigerated storage and antiseptic treatment are required, which may cause an increase in cost.
  • the micronized cellulose will aggregate, keratinize, or form a film, and the expected function will not be stable when used as an additive. and may not appear. Furthermore, since the solid content concentration of CNF is low, a large amount of energy is required for the solvent removal process itself by drying, which is a hurdle to business feasibility.
  • Patent Document 8 describes composite particles containing a coating layer composed of cellulose fibers and a polymer covered with the coating layer.
  • this composite particle since the cellulose fiber and the polymer are integrated, they can be easily separated by filtration and distributed as powder. The redispersibility of the powder is also good.
  • Patent Document 8 Although the composite particles described in Patent Document 8 are excellent as a material that exhibits the properties of CNF as described above, there is room for improvement in that the types of applicable polymers are limited. When forming composite particles from a resin material that is difficult to apply, the yield drops significantly, the particle size distribution of the obtained particles increases, and the amount of CNF present on the surface of the particles is small. There are various problems such as not fully demonstrating
  • an object of the present invention is to provide composite particles of cellulose fibers that are excellent in handleability and have high versatility, and a method for producing the same.
  • a first aspect of the present invention is a method for producing composite particles.
  • This production method includes a first step of defibrating a cellulose raw material in a dispersion solvent to obtain a micronized cellulose dispersion in which micronized cellulose is dispersed, and adding an organic onium compound or an amine to the micronized cellulose dispersion. a second step of obtaining an ion-bonded micronized cellulose dispersion containing micronized cellulose bound with organic onium ions or ammonium ions; and a fourth step of solidifying the core particle precursor to form core particles and obtaining composite particles in which the core particles are coated with micronized cellulose that is inseparably bound to the core particles.
  • a second aspect of the present invention comprises a core particle comprising at least one polymer, and micronized cellulose having anionic functional groups disposed on the surface of the core particle inseparably bound to the core particle.
  • Composite particles In this composite particle, organic onium ions or ammonium ions are bound to at least part of the micronized cellulose.
  • FIG. 1 is a schematic diagram of a composite particle according to one embodiment of the present invention
  • FIG. It is a figure which shows an example of the manufacturing method of the same composite particle.
  • 4 is a graph showing the results of measuring the spectral transmission spectrum of an aqueous dispersion of cellulose nanofibers according to an example. It is a graph which shows the result of having performed steady-state viscoelasticity measurement using the rheometer with respect to the same aqueous dispersion.
  • 4 is a scanning electron microscope image of composite particles according to an example.
  • 4 is a scanning electron microscope image of composite particles according to an example.
  • 4 is a scanning electron microscope image of composite particles according to an example.
  • 4 is a scanning electron microscope image of composite particles according to an example.
  • 4 is a scanning electron microscope image of composite particles according to a comparative example.
  • 4 is a scanning electron microscope image of composite particles according to a comparative example. 4 is a graph showing particle size distributions of composite particles according to Examples and Comparative Examples
  • FIG. 1 shows a schematic diagram of a composite particle 5 according to this embodiment.
  • Composite particle 5 comprises core particle 3 and micronized cellulose 1 located on the surface of core particle 3 .
  • the micronized cellulose 1 is combined with the core particle 3 and is inseparable.
  • the mode of bonding between the micronized cellulose 1 and the core particles 3 is not particularly limited. It is preferable to form the coating layer 10 which consists of layers.
  • Organic onium cations or amines 7a are bound to at least part of the micronized cellulose 1 as counter cations.
  • the ionized state of the organic onium compound may be referred to as “organic onium ion” or “organic onium cation”.
  • the term "amine” as used herein includes partially or wholly ionized ammonium ions.
  • organic onium compound/amine an organic onium compound or an amine, or an organic onium cation or an ammonium ion
  • organic onium compound/amine organic onium cation (or organic onium ion)/ammonium ion
  • Composite particles 5 of the present embodiment are produced in an O/W type Pickering emulsion using micronized cellulose 1 to which organic onium ions/ammonium ions 7a are bound as counter cations (counter ions) of anionic functional groups. It is obtained by solidifying a core particle precursor (hereinafter also simply referred to as “droplets”) present as (oil phase, oil particles, dispersed phase).
  • a core particle precursor hereinafter also simply referred to as “droplets” present as (oil phase, oil particles, dispersed phase).
  • the core particle precursor may be any material as long as it solidifies to form a core particle, and is, for example, a polymerizable compound, a molten polymer, or a dissolved polymer. Solidification of the core particle precursor can be accomplished in a variety of ways. For example, a monomer having a polymerizable functional group (hereinafter also referred to as a "polymerizable monomer”) is used as a core particle precursor, and a polymerization granulation method (emulsion polymerization method, suspension polymerization method) in which particles are formed in the polymerization process.
  • a polymerizable monomer emulsion polymerization method, suspension polymerization method
  • solidifying the core particle precursor means (A) polymerizing the polymerizable monomer droplets, (B) cooling the molten polymer droplets to solidify them, and (C) dissolving the It is a concept that includes all of solidification by removing the solvent from the polymer droplets.
  • the O/W Pickering emulsion is stabilized by adsorption of the micronized cellulose 1 on the interface of droplets containing the core particle precursor dispersed in the dispersion solvent of the continuous phase (aqueous phase).
  • aqueous phase a continuous phase
  • composite particles 5 can be produced using the emulsion as a template.
  • the "stabilized state of the emulsion” means a state in which the droplet size of the emulsion does not change even if it is allowed to stand still for a long period of time (for example, 12 hours).
  • the emulsion is unstable, some of the droplets coalesce over time, causing the particle size distribution of the droplets to shift to a larger size compared to the initial stage, or to cause variations in the particle size distribution. Furthermore, in some cases separation of oil and water phases occurs. As a result, the yield of the composite particles obtained may decrease, and the particle diameters of the composite particles may become non-uniform.
  • finely divided cellulose 1 in which organic onium ions/ammonium ions 7a are bonded as counter ions of anionic functional groups a stable O/W type Pickering emulsion is formed with many core particle precursors. Therefore, composite particles 5 having a small particle size and uniformity can be obtained at a high yield.
  • micronized cellulose 1 which is solid particles that have been micronized to submicron order, is adsorbed on the interface of droplets by physical force, forming a cellulose barrier against the aqueous phase. Once adsorbed and an interface is formed, the emulsion structure is stabilized because greater energy is required for desorption.
  • the micronized cellulose 1 has amphipathic properties, and the hydrophobic side of the micronized cellulose 1 is adsorbed to droplets having hydrophobicity, and the hydrophilic side of the micronized cellulose 1 is directed to the hydrophilic dispersion solvent. As a result, the effect of improving the stability of the droplet interface is also presumed.
  • the adsorptive power of the micronized cellulose 1 at this interface is determined by the high affinity of the solid particles for the oil phase and the aqueous phase, that is, the affinity of the micronized cellulose 1 for the core particle precursor and the dispersion solvent of the micronized cellulose 1. depends on both the affinity for
  • the affinity of the micronized cellulose 1 for droplets containing the core precursor is increased, and the adsorptive power is improved.
  • a stable O/W-type Pickering emulsion can be formed using a large amount of core precursor, and composite particles 5 having a small particle size and a uniform particle size can be obtained at a high yield.
  • an organic onium compound / amine is used, and the counter ion of the anionic functional group of the finely divided cellulose 1 is an organic onium ion / A method using ammonium ions 7a is preferred.
  • an organic onium compound/ A method of adding an amine and stirring for a while is mentioned.
  • the term “inseparable” indicating the bonding state between the core particles 3 and the micronized cellulose 1 means that the micronized cellulose 1 and the core particles 3 cannot be separated even after performing a predetermined separation operation. However, it means that the state of covering the core particles 3 with the micronized cellulose 1 is maintained.
  • the predetermined separation operation is, for example, an operation of centrifuging the dispersion containing the composite particles 5 to remove the supernatant, then adding a solvent and redispersing to purify and wash the composite particles 5, or a membrane filter. An operation of repeating the operation of washing with a solvent repeatedly by filtration washing using is mentioned.
  • the coating state of the core particles 3 with the micronized cellulose 1 can be confirmed by surface observation of the composite particles 5 with a scanning electron microscope (SEM). Although the detailed mechanism by which the micronized cellulose 1 and the core particles 3 are inseparably bonded has not been clarified, the composite particles 5 are produced using an O/W emulsion stabilized by the micronized cellulose 1 as a template. Therefore, when the solidification of the droplet proceeds while the micronized cellulose 1 is in contact with the droplet inside the emulsion, part of the micronized cellulose 1 is fixed while remaining in the droplet, and finally the core It is believed that the particles 3 and micronized cellulose 1 are inseparably bound. O/W emulsions are also called oil-in-water emulsions, in which water is a continuous phase in which oil is dispersed as oil droplets (oil particles).
  • the composite particles 5 are produced using an O/W emulsion stabilized by the micronized cellulose 1 as a template, one of their characteristics is that they have a shape close to a true sphere derived from the O/W emulsion.
  • composite particles 5 having a uniform particle size can be obtained from a stable O/W emulsion.
  • the coating layer 10 containing the micronized cellulose 1 is formed on the surface of the spherical core particle 3 with a relatively uniform thickness.
  • the composite particles 5 of the present embodiment are spherical, and preferably spherical.
  • the micronized cellulose 1 forms a stable O/W-type Pickering emulsion, whereby spherical composite particles 5 can be obtained.
  • the index of sphericity can be evaluated from circularity.
  • the degree of circularity is preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.9 or more.
  • the circularity can be calculated as the average circularity of 1000 or more particles measured by an image analysis type particle size distribution meter.
  • the calculated average circularity may be used as an index of the sphericity.
  • the particle size of the composite particles 5 can be confirmed by optical microscope observation.
  • the average particle size can be calculated by taking the average value of the diameters of the composite particles 5 after randomly measuring 100 locations.
  • the calculated average particle diameter may be used as the particle diameter of the composite particles 5 .
  • the average particle diameter is not particularly limited, it is preferably 0.01 ⁇ m or more and 1000 ⁇ m or less.
  • the average particle size is more preferably 0.05 ⁇ m or more and 100 ⁇ m or less, and still more preferably 0.10 ⁇ m or more and 50 ⁇ m or less.
  • Composite particles 5 having a small average particle size can be obtained by the micronized cellulose 1 adsorbing to the liquid-liquid interface to form a stable Pickering emulsion.
  • the maximum particle size of the composite particles 5 can be obtained by randomly measuring 100 composite particles 5 with an optical microscope and taking the maximum value of the diameter. Although not particularly limited, the maximum particle size of the composite particles 5 is preferably 200 ⁇ m or less, more preferably 100 ⁇ m or less, and even more preferably 50 ⁇ m or less. Since the composite particles 5 in the present embodiment can be obtained using a stable emulsion as a template, the maximum particle size is small.
  • a particle size distribution analyzer such as a laser diffraction particle size distribution analyzer or an image analysis particle size distribution analyzer can also be used to measure the particle size.
  • the micronized cellulose 1 preferably forms a coating layer 10 on the surface of the core particles 3 .
  • the coating layer 10 preferably covers the entire surface of the core particle 3, but does not necessarily have to cover the entire surface.
  • the thickness of the coating layer 10 composed of the micronized cellulose 1 is not particularly limited, it is preferably 3 nm or more and 1000 nm or less.
  • the average thickness of the coating layer 10 is obtained by cutting a resin piece in which the composite particles 5 are fixed with the embedding resin with a microtome and performing SEM observation. It is obtained by randomly measuring 100 points and calculating the arithmetic mean value.
  • Another feature of the composite particles 5 is that the coating layer 10 has a uniform thickness.
  • the coefficient of variation of the value of the thickness of the coating layer 10 (the standard deviation of 30 points randomly extracted from the 100 points described above) is preferably 0.5 or less, more preferably 0.4 or less.
  • the micronized cellulose 1 in the present embodiment is a fiber made of cellulose or a cellulose derivative and having a number average minor axis diameter of 1 nm or more and 1000 nm or less, such as cellulose nanofiber (CNF).
  • CNF is micronized cellulose 1 that can be obtained by pulverizing a cellulose raw material obtained from wood or the like into ultrafine fibers, and is safe and biodegradable.
  • the micronized cellulose 1 preferably has a fibrous shape derived from a microfibril structure. Specifically, the micronized cellulose 1 is fibrous, has a number average minor axis diameter of 1 nm or more and 1000 nm or less, a number average major axis diameter of 50 nm or more, and a number average minor axis diameter of is preferably 5 times or more. Moreover, the crystallinity of the micronized cellulose 1 is preferably 50% or more. The crystal structure of the micronized cellulose 1 is preferably cellulose I type.
  • the crystal surface of the micronized cellulose 1 of the present embodiment preferably has an anionic functional group.
  • the anionic functional group include, but are not particularly limited to, a carboxy group, a phosphate group, and a sulfo group. Among them, a carboxy group and a phosphate group are preferred, and a carboxy group is preferred because of ease of selective introduction to the cellulose crystal surface.
  • the micronized cellulose 1 in the present embodiment is not particularly limited, it has an anionic functional group on the crystal surface, and the content of the anionic functional group is 0.1 mmol/g or more and 5.0 mmol per micronized cellulose. /g or less. More preferably, it is 0.5 mmol/g or more and 2.0 mmol/g or less. If it is less than 0.1 mmol/g, the stability of the emulsion may deteriorate, resulting in a wide particle size distribution. Moreover, if it exceeds 5.0 mmol/g, it may become difficult to stably produce the composite particles 5 .
  • the amount of anionic functional groups on the surface side of the micronized cellulose 1 bonded to the composite particles 5 in the present embodiment is preferably 0.01 ⁇ mol/g or more per composite particle, more preferably 0.10 ⁇ mol/g. g or more and preferably 100 ⁇ mol/g or less, more preferably 50 ⁇ mol/g or less, and even more preferably 10 ⁇ mol/g or less. If it is less than 0.01 ⁇ mol/g, the emulsion stability may be poor and the particle size distribution may become wide. Moreover, if it exceeds 100 ⁇ mol/g, it may become difficult to stably produce the composite particles 5 .
  • the amount of anionic functional groups on the micronized cellulose 1 and on the surface side of the micronized cellulose 1 bound to the composite particles 5 is not particularly limited, but can be measured by electrical conductivity titration. Take a sample in a beaker, disperse it in ion-exchanged water, add 0.01 mol/L sodium chloride aqueous solution, add 0.1 mol/L hydrochloric acid while stirring, adjust the pH to 2 as a whole, and perform automatic titration.
  • the average bonding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 is preferably 0.02 mmol/g or more, more preferably 0.2 mmol/g or more per micronized cellulose from the viewpoint of emulsion stability. Yes, preferably 3 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2 mmol/g or less. Any two or more organic onium ions/ammonium ions 7a may be introduced into the micronized cellulose 1 at the same time. It is preferable that the total amount is within the above range.
  • the average binding amount (mmol/g) of organic onium ion/ammonium ion 7a can be measured by a known method. For example, it can be calculated by titration, IR measurement, or the like.
  • the average binding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 used in the present embodiment is preferably 0.01 equivalent or more, more preferably 0.05 equivalent or more with respect to the anionic functional group. and is preferably 0.8 equivalents or less, more preferably 0.50 equivalents or less, and still more preferably 0.30 equivalents or less.
  • the average binding amount is 0.01 equivalent or more and 0.8 equivalent or less, the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, the particle size is small, This is preferable because uniform composite particles 5 can be obtained at a high yield.
  • the binding amount of the organic onium ion/ammonium ion 7a is less than 0.01 equivalent, the surface of the micronized cellulose 1 is not sufficiently hydrophobized, and the particle size tends to vary, resulting in a decrease in yield. On the other hand, if it exceeds 0.8 equivalents, the organic onium ion/ammonium ion 7a may decompose the micronized cellulose 1 or lower the affinity for the dispersion medium, which is not preferable.
  • the average binding amount (equivalent) of the organic onium ion/ammonium ion 7a is defined by A being the average binding amount (mmol/g) of the organic onium ion/ammonium ion 7a per micronized cellulose, and the amount of anionic functional groups per micronized cellulose. If (mmol/g) is B, it can be calculated as A/B.
  • the average binding amount of organic onium ions/ammonium ions 7a bound to the surface side of the micronized cellulose 1 of the composite particles 5 is preferably 0.01 ⁇ mol/g or more per composite particle, more preferably 0.01 ⁇ mol/g or more, from the viewpoint of emulsion stability. is 0.1 ⁇ mol/g or more, preferably 100 ⁇ mol/g or less, more preferably 50 ⁇ mol/g or less, still more preferably 10 ⁇ mol/g or less. When the average bonding amount of organic onium ions/ammonium ions 7a is within this range, the composite particles 5 have good dispersibility. Any two or more organic onium ions/ammonium ions 7a may be introduced into the micronized cellulose 1 at the same time.
  • the average binding amount ( ⁇ mol/g) of organic onium ion/ammonium ion 7a can be measured by a known method. For example, by washing the composite particles 5 with an acid such as hydrochloric acid, the organic onium ions/ammonium ions 7a can be separated from the composite particles 5 and calculated by liquid chromatography, titration, IR measurement, or the like.
  • the average binding amount of the organic onium ions/ammonium ions 7a bound to the surface side of the micronized cellulose 1 of the composite particles 5 is 0 with respect to the anionic functional groups present on the surface of the micronized cellulose 1 bonded to the composite particles 5. It is preferably 0.01 equivalent or more, more preferably 0.05 equivalent or more, and preferably 1.00 equivalent or less, more preferably 0.50 equivalent or less, and still more preferably 0.25 equivalent or less. be. When the average bonding amount of organic onium ions/ammonium ions 7a is within this range, the dispersibility and stability of the micronized cellulose 1 are good, so composite particles 5 with high dispersion stability can be obtained in a high yield.
  • the average bonding amount (equivalent) of the organic onium ion/ammonium ion 7a is determined by C being the average bonding amount (mmol/g) of the organic onium ion/ammonium ion 7a per composite particle, and the amount of anionic functional groups per composite particle (mmol /g) is D, it can be calculated as C/D.
  • the contact angle to water of the film produced using the micronized cellulose 1 is 45° or more, and more preferably 50° or more.
  • the contact angle was measured by pouring a 0.5% aqueous dispersion of micronized cellulose 1 into a 5 cm x 5 cm container, drying it at a temperature of 30°C and humidity of 80%, and then drying the film under a nitrogen atmosphere.
  • the contact angle can be obtained by dropping 2 ⁇ l of pure water using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., PCA-1).
  • a cationic substance other than the organic onium ion/ammonium ion 7a may be bound as a counter ion.
  • cationic substances include, but are not limited to, alkali metals such as sodium ions, potassium ions and lithium ions, and metal ions such as alkaline earth metals such as magnesium ions and calcium ions. From the viewpoint of the dispersion stability of the micronized cellulose 1, alkali metal ions such as sodium ions, potassium ions, and lithium ions are preferred.
  • the binding equivalent of the cationic substance other than the organic onium ion/ammonium ion 7a is preferably 0.02 mmol/g or more per 1 micronized cellulose, from the viewpoint of the dispersion stability and emulsion stability of the micronized cellulose 1, More preferably, it is 0.2 mmol/g or more. Also, it is preferably 3 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2 mmol/g or less. Any two or more cationic substances may be introduced into the micronized cellulose 1 at the same time.
  • the average binding amount (mmol/g) of the cationic substance can be measured by a known method.
  • the EPMA (Electron Probe Micro Analyzer) method using an electron beam microanalyzer, X-ray fluorescence analysis, and ICP (Inductively Coupled Plasma) emission spectrometry are examples of simple methods for elemental analysis.
  • the amount of the cationic substance that binds to the anionic functional group is not particularly limited, it is 0.95 equivalent or less, preferably 0.90 or less, more preferably 0.80, relative to the anionic functional group of the micronized cellulose 1. It is below. If the amount of cationic substance exceeds 0.95 equivalents, the emulsion stability may be low, resulting in low yield and broad particle size distribution.
  • the average binding amount (equivalent) of the cationic substance is defined by E as the average binding amount (mmol/g) of the cationic substance per 1 micronized cellulose, and the anionic functional group content (mmol/g) per 1 micronized cellulose. If B is used, the calculation can be performed by E/B.
  • the binding equivalent of the cationic substance other than the organic onium ion/ammonium ion 7a is preferably 0.01 ⁇ mol/g or more per composite particle, more preferably It is 0.1 ⁇ mol/g or more. Also, it is preferably 100 ⁇ mol/g or less, more preferably 50 ⁇ mol/g or less, and even more preferably 10 ⁇ mol/g or less. When the binding amount of the cationic substance is within this range, the composite particles 5 have good dispersibility. Any two or more cationic substances may be introduced into the micronized cellulose 1 on the surface of the composite particles 5 at the same time.
  • the average binding amount ( ⁇ mol/g) of the cationic substance can be measured by a known method.
  • a known method for example, in the case of metal ions, an EPMA method using an electron beam microanalyzer, a fluorescent X-ray analysis method, an elemental analysis by ICP emission spectrometry, and the like can be exemplified as simple methods.
  • the composite particles 5 may be washed with an acid such as hydrochloric acid to separate the cationic substance and then analyzed by elemental analysis or the like.
  • the average binding amount of the cationic substance bound to the surface side of the micronized cellulose 1 of the composite particles 5 is 0.01 equivalent or more with respect to the anionic functional groups present on the surface of the micronized cellulose 1 bonded to the composite particles 5. is preferably 0.05 equivalents or more, preferably 1.00 equivalents or less, more preferably 0.50 equivalents or less, and even more preferably 0.25 equivalents or less. .
  • the average binding amount of the cationic substance is within this range, the stability of the micronized cellulose 1 is good, the emulsion stability is good, and the composite particles 5 can be obtained in a high yield. The dispersibility of is also improved.
  • the average binding amount (equivalent) of the cationic substance is given by the average binding amount (mmol/g) of the cationic substance per composite particle, F, and the anionic functional group amount (mmol/g) per composite particle, D. It can be calculated in F/D.
  • the core particles 3 preferably contain at least one type of polymer.
  • a known polymer can be used as the polymer, and a polymer obtained by polymerizing a polymerizable monomer by a known method may be used.
  • polymers examples include acrylic polymers, epoxy polymers, polyester polymers, amino polymers, silicone polymers, fluorine polymers, and urethane/isocyanate polymers.
  • a biodegradable polymer can be used for the core particle 3 of this embodiment.
  • the polymer is preferably a biodegradable polymer.
  • Biodegradability refers to a polymer that decomposes and disappears in the global environment such as soil and seawater, and/or a polymer that decomposes and disappears in vivo. In general, polymers are degraded by enzymes possessed by microorganisms in soil or seawater, whereas in vivo they are degraded by physicochemical hydrolysis without the need for enzymes.
  • Degradation of a polymer means that the polymer becomes low-molecular-weight or water-soluble and loses its shape.
  • Decomposition of the polymer is not particularly limited, but occurs by hydrolysis of the main chain, side chains and cross-linking points, and oxidative decomposition of the main chain.
  • Biodegradable polymers include natural polymers derived from nature and synthetic polymers.
  • natural polymers include polysaccharides produced by plants (cellulose, starch, alginic acid, etc.), polysaccharides produced by animals (chitin, chitosan, hyaluronic acid, etc.), proteins (collagen, gelatin, albumin, etc.), and those produced by microorganisms. polyester (poly(3-hydroxyalkanoate)), polysaccharide (hyaluronic acid, etc.) and the like.
  • Synthetic polymers include, for example, aliphatic polyesters, polyols, and polycarbonates.
  • Fatty acid polyesters include, for example, glycol-dicarboxylic acid polycondensation systems (polyethylene succinate, polybutylene succinate, etc.), polylactides (polyglycolic acid, polylactic acid, etc.), polylactones ( ⁇ -caprolactone, ⁇ -caprolactone, etc.). , and others (polybutylene terephthalate, adipate, etc.).
  • polyols examples include polyvinyl alcohol.
  • polycarbonate examples include polyester carbonate.
  • polyacid anhydrides polycyanoacrylates, polyorthoesters, polyphosphazenes, etc. are also biodegradable synthetic polymers.
  • the core particles 3 may contain other components in addition to the polymer.
  • colorants oil absorbers, light shielding agents (ultraviolet absorbers, ultraviolet scattering agents, etc.), antibacterial agents, antioxidants, antiperspirants, antifoaming agents, antistatic agents, binders, bleaching agents, chelating agents, Deodorizing ingredients, fragrances, fragrances, anti-dandruff actives, emollients, insect repellents, preservatives, natural extracts, beauty ingredients, pH adjusters, vitamins, amino acids, hormones, oils and waxes and other oil-based ingredients , surfactants, inorganic particles (titanium oxide, silica, clay, etc.), and the like.
  • the content of other components in the composite particles 5 is not particularly limited, and is preferably within a range in which the composite particles 5 can stably maintain their shape.
  • the content of other components is preferably 0.001 parts by mass or more and 80 parts by mass or less when the composite particles 5 are 100 parts by mass.
  • the method for producing composite particles according to the present embodiment includes a first step of defibrating a cellulose raw material in a dispersion solvent 4 to obtain a micronized cellulose dispersion in which micronized cellulose 1 is dispersed, and a micronized cellulose dispersion.
  • the composite particles 5 obtained by the above production method are obtained as a dispersion.
  • a dry solid of composite particles 5 with good handleability is obtained.
  • the method of removing the dispersion solvent 4 is not particularly limited, and examples thereof include a method of removing the dispersion solvent 4 by a centrifugal separation method or a filtration method, and a method of removing the dispersion solvent 4 by evaporating it in an oven or the like.
  • a dry solid of composite particles 5 may be obtained by purification and drying. At this time, the dry solid matter of the composite particles 5 obtained does not form a film or an aggregate, but is a fine powder.
  • the reason for this is not clear, in the case of the dispersion containing the composite particles 5, since the composite particles 5 are substantially spherical composite particles 5 in which the micronized cellulose 1 is immobilized on the surface, even if the dispersion solvent 4 is removed, the micronized
  • the cellulose 1 does not agglomerate and the adjacent composite particles are only in point contact with each other. Since the composite particles 5 do not aggregate, it is easy to redisperse the composite particles 5 obtained as a dry powder in a solvent. show gender.
  • the dry powder of the composite particles 5 is a dry solid that contains almost no solvent and is redispersible in a solvent.
  • the solid content can be 80% or more, Further, it can be 90% or more, and further can be 95% or more. Since the dispersion of the composite particles 5 can be almost easily removed from the solvent, favorable effects can be obtained from the viewpoints of reduction in transportation costs, prevention of spoilage, improvement in addition rate, and improvement in kneading efficiency with the resin. Even when the solid content is increased to 80% or more by drying, the micronized cellulose 1 easily absorbs moisture. The following may occur.
  • the solid content of the dry powder containing the composite particles 5 should be 80% or more. It should be said that any dry solid obtained through the process of is included in the technical scope of the present invention. Each step of the manufacturing method will be described in detail below.
  • the first step is a step of defibrating the cellulose raw material in the dispersion solvent 4 to obtain a fine cellulose dispersion.
  • various cellulose raw materials are dispersed in the dispersion solvent 4 to form a suspension.
  • the concentration of the cellulose raw material in the suspension is preferably 0.1% or more and less than 10%. If the concentration of the cellulose raw material in the suspension is less than 0.1%, the amount of solvent becomes excessive, which tends to impair productivity, which is not preferable. Further, if the concentration of the cellulose raw material in the suspension is 10% or more, the suspension will rapidly increase in viscosity as the cellulose raw material is defibrated, and uniform defibration tends to become difficult, which is not preferable. .
  • the dispersion solvent 4 used for preparing the suspension preferably contains 50% or more water. If the proportion of water in the suspension is less than 50%, the dispersion of the micronized cellulose 1 tends to be inhibited in the process of obtaining a micronized cellulose dispersion by fibrillating the cellulose raw material in the dispersion solvent 4, which will be described later.
  • a hydrophilic solvent is preferable as the solvent contained in addition to water.
  • the hydrophilic solvent is not particularly limited, but alcohols such as methanol, ethanol and isopropanol, and cyclic ethers such as tetrahydrofuran are preferred. If necessary, the pH of the suspension may be adjusted, for example, in order to increase the dispersibility of the cellulose and the micronized cellulose 1 to be produced.
  • alkaline aqueous solutions used for pH adjustment include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide (tetramethylammonium hydroxide, TMAH) aqueous solution, and tetraethylammonium hydroxide.
  • organic onium compounds such as (tetraethylammonium hydroxide, TEAH) aqueous solution, tetrabutylammonium hydroxide (tetrabutylammonium hydroxide, TBAH) aqueous solution, and benzyltrimethylammonium hydroxide aqueous solution;
  • TEAH tetraethylammonium hydroxide
  • TBAH tetrabutylammonium hydroxide
  • benzyltrimethylammonium hydroxide aqueous solution benzyltrimethylammonium hydroxide aqueous solution
  • a sodium hydroxide aqueous solution is preferable from the viewpoint of cost.
  • the suspension is subjected to a physical defibration process to refine the cellulose raw material.
  • the method of physical fibrillation treatment is not particularly limited, but for example, high pressure homogenizer, ultra high pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer. , nanogenizer, and mechanical treatments such as underwater counter-collision.
  • the cellulose in the suspension is made finer, and at least one side of the structure is made finer to the order of nanometers (micronized cellulose 1) dispersion liquid. can be obtained.
  • the number average minor axis diameter and the number average major axis diameter of the micronized cellulose 1 to be obtained can be adjusted by the time and frequency of the physical defibration treatment at this time.
  • a dispersion (micronized cellulose dispersion) of the micronized cellulose 1, which is micronized so that at least one side of the structure is on the order of nanometers, is obtained.
  • the resulting dispersion can be used as it is or after dilution, concentration, etc., as a stabilizer for an O/W emulsion, which will be described later.
  • the dispersion of the micronized cellulose 1 may optionally contain other components other than the cellulose and the components used for adjusting the pH within a range that does not impair the effects of the present invention.
  • the other components are not particularly limited, and can be appropriately selected from known additives according to the use of the composite particles 5 and the like.
  • organometallic compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic acicular minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, Ultraviolet absorbers, stabilizers, magnetic powders, orientation promoters, plasticizers, cross-linking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxides and the like.
  • the micronized cellulose 1 usually has a fiber shape derived from a microfibril structure
  • the micronized cellulose 1 used in the production method of the present embodiment preferably has a fiber shape within the range shown below. That is, the shape of the micronized cellulose 1 is preferably fibrous.
  • the number average minor axis diameter of the fibrous micronized cellulose 1 should be 1 nm or more and 1000 nm or less, preferably 2 nm or more and 500 nm or less.
  • the number average minor axis diameter is not particularly limited, but it is preferably five times or more the number average minor axis diameter. If the number average major axis diameter is less than five times the number average minor axis diameter, it tends to be difficult to sufficiently control the size and shape of the composite particles 5, which is not preferable.
  • the number average minor axis diameter of the micronized cellulose 1 is obtained by measuring the minor axis diameter (minimum diameter) of 100 fibers by, for example, transmission electron microscope observation or atomic force microscope observation, and calculating the average value thereof.
  • the number average major axis diameter of the micronized cellulose 1 is obtained by measuring the major axis diameter (maximum diameter) of 100 fibers by, for example, transmission electron microscopy or atomic force microscopy, and calculating the average value. .
  • raw materials composed of type I cellulose crystals include, in addition to natural wood cellulose, non-wood natural cellulose such as cotton linter, bamboo, hemp, bagasse, kenaf, bacterial cellulose, sea squirt cellulose, and valonia cellulose. can be used. Furthermore, regenerated cellulose represented by rayon fibers and cupra fibers composed of cellulose type II crystals can also be used. It is preferable to use wood-based natural cellulose as a raw material because of the ease of material procurement.
  • the wood-based natural cellulose is not particularly limited. For example, softwood pulp, hardwood pulp, waste paper pulp, and the like, which are generally used for producing cellulose nanofibers, can be used. Softwood pulp is preferred because of its ease of refining and miniaturization.
  • the micronized cellulose raw material is chemically modified. More specifically, it is preferable that an anionic functional group is introduced to the crystal surface of the micronized cellulose raw material. This is because the presence of an anionic functional group on the surface of the cellulose crystals facilitates penetration of the solvent into the space between the cellulose crystals due to the effect of osmotic pressure, thereby facilitating the miniaturization of the cellulose raw material.
  • the type and introduction method of the anionic functional group to be introduced into the crystal surface of cellulose are not particularly limited, and a carboxy group and a phosphate group, such as a carboxy group, a phosphate group, and a sulfo group, are preferred.
  • a carboxy group is preferred because of its ease of selective introduction to the cellulose crystal surface.
  • the method of introducing carboxyl groups onto the surface of cellulose fibers is not particularly limited. Specifically, for example, carboxymethylation may be performed by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a high-concentration alkaline aqueous solution. Alternatively, a carboxyl group may be introduced by directly reacting a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave with cellulose. Furthermore, under relatively mild conditions of an aqueous system, a co-oxidant is added in the presence of an N-oxyl compound such as TEMPO, which has a high selectivity for the oxidation of alcoholic primary carbon while maintaining the structure as much as possible. You may use the method used. Oxidation using an N-oxyl compound is more preferable for the selectivity of the carboxy group-introducing site and the reduction of the environmental load.
  • examples of the N-oxyl compound include TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy radical), 2,2,6,6-tetramethyl-4-hydroxypiperidine- 1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2, 2,6,6-tetramethylpiperidine-N-oxyl, and the like.
  • TEMPO which has high reactivity, is preferable.
  • the amount of the N-oxyl compound to be used is not particularly limited and may be the amount required for the catalyst. Usually, it is about 0.01 to 5.0% by mass based on the solid content of wood-based natural cellulose to be oxidized.
  • an oxidation method using an N-oxyl compound for example, wood-based natural cellulose is dispersed in water, and an oxidation treatment is performed in the presence of an N-oxyl compound. At this time, it is preferable to use a co-oxidizing agent together with the N-oxyl compound.
  • the N-oxyl compound is sequentially oxidized by the co-oxidizing agent in the reaction system to form an oxoammonium salt, and the oxoammonium salt oxidizes the cellulose.
  • this oxidation treatment the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group is improved. If the oxidation treatment is performed under mild conditions, the crystalline structure of cellulose can be easily maintained.
  • co-oxidants examples include halogens, hypohalous acids, halogenous acids and perhalogenates, salts thereof, halogen oxides, nitrogen oxides, peroxides, etc., which can promote the oxidation reaction. Any oxidizing agent, if any, can be used. Sodium hypochlorite is preferred because of its availability and reactivity.
  • the amount of the co-oxidizing agent to be used is not particularly limited and may be an amount capable of promoting the oxidation reaction. Usually, it is about 1 to 200% by mass based on the solid content of the wood-based natural cellulose to be oxidized.
  • At least one compound selected from the group consisting of bromides and iodides may be used in combination with the N-oxyl compound and the co-oxidizing agent.
  • the oxidation reaction can proceed smoothly, and the introduction efficiency of the carboxy group can be improved.
  • sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable in terms of cost and stability.
  • the amount of the compound to be used is not particularly limited as long as it can promote the oxidation reaction. Usually, it is about 1 to 50% by mass based on the solid content of the wood-based natural cellulose to be oxidized.
  • the reaction temperature of the oxidation reaction is preferably 4° C. or higher and 80° C. or lower, more preferably 10° C. or higher and 70° C. or lower.
  • the reaction temperature of the oxidation reaction is lower than 4°C, the reactivity of the reagent tends to decrease and the reaction time tends to become longer.
  • the reaction temperature of the oxidation reaction exceeds 80°C, the side reaction is accelerated, the cellulose sample becomes low-molecular, and the highly crystalline, rigid, micronized cellulose 1-fiber structure collapses, stabilizing the O/W emulsion. It tends to be difficult to use as an agent.
  • the reaction time of the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy groups, etc., and is not particularly limited, but is usually about 10 minutes to 5 hours.
  • the pH of the reaction system during the oxidation reaction is not particularly limited, it is preferably 9-11.
  • the pH is 9 or more, the reaction can proceed efficiently. If the pH exceeds 11, side reactions may proceed and the decomposition of the sample cellulose may be accelerated.
  • the oxidation treatment as the oxidation progresses, carboxyl groups are generated and the pH in the system decreases, so it is preferable to maintain the pH of the reaction system at 9 to 11 during the oxidation treatment.
  • a method of maintaining the pH of the reaction system at 9 to 11 for example, a method of adding an alkaline aqueous solution according to the decrease in pH can be mentioned.
  • alkaline aqueous solutions include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide (tetramethylammonium hydroxide, TMAH) aqueous solution, tetraethylammonium hydroxide (tetraethylammonium hydroxide , TEAH) aqueous solution, tetrabutylammonium hydroxide (tetrabutylammonium hydroxide, TBAH) aqueous solution, and organic onium compounds such as benzyltrimethylammonium hydroxide aqueous solution.
  • TMAH tetramethylammonium hydroxide
  • TEAH tetraethylammonium hydroxide
  • TBAH tetrabutylammonium hydroxide
  • organic onium compounds such as benzyltrimethylammonium hydro
  • a sodium hydroxide aqueous solution, a lithium hydroxide aqueous solution, and a potassium hydroxide aqueous solution are preferable from the viewpoint of cost.
  • a cationic substance contained in the alkaline aqueous solution used to maintain the pH during the oxidation reaction binds as a counterion to the carboxy group generated by the oxidation reaction.
  • the cationic substance of the counter ion of the carboxy group of the TEMPO-oxidized cellulose is preferably alkali metal ions such as sodium ion, potassium ion and lithium ion, and metal ions such as alkaline earth metal such as magnesium ion and calcium ion.
  • the organic onium ion/ammonium ion 7a has a strong ionization tendency. easily binds to the anionic functional group of the micronized cellulose 1 as a counterion.
  • the oxidation reaction by the N-oxyl compound can be stopped, for example, by adding alcohol to the reaction system. At this time, it is preferable to keep the pH of the reaction system within the above range.
  • alcohol to be added for example, low-molecular-weight alcohols such as methanol, ethanol and propanol are preferable in order to quickly complete the reaction, and ethanol is particularly preferable in view of the safety of by-products produced by the reaction.
  • the reaction solution after the oxidation treatment may be directly subjected to the micronization step, but in order to remove catalysts such as N-oxyl compounds, impurities, etc., the oxidized cellulose contained in the reaction solution is recovered and washed with a washing solution.
  • the TEMPO-oxidized cellulose can be collected by a known method such as filtration using a glass filter or a nylon mesh with a pore size of 20 ⁇ m. Pure water or an acidic solution such as hydrochloric acid is preferable as the cleaning liquid used for cleaning the TEMPO-oxidized cellulose.
  • the counterions of the carboxyl groups of the TEMPO-oxidized cellulose are maintained without being replaced, so the counterions of the carboxyl groups of the TEMPO-oxidized cellulose after washing become metal ions. Also, by washing with an acid such as hydrochloric acid, it is possible to remove at least part of the counterions and convert the carboxy groups of the TEMPO-oxidized cellulose to COOH.
  • the carboxy group of TEMPO-oxidized cellulose is COOH or the counter ion is a metal ion
  • the organic onium ion/ammonium ion 7a has a strong ionization tendency. easily binds to the anionic functional group of the micronized cellulose 1 as a counterion.
  • TEMPO-oxidized cellulose nanofibers (hereinafter also referred to as TEMPO-oxidized CNF, cellulose single nanofibers, CSNF) having a uniform fiber width of about 3 nm are obtained.
  • TEMPO-oxidized CNF cellulose single nanofibers
  • CSNF cellulose single nanofibers
  • the CSNF used in the present embodiment can be obtained by a process of oxidizing a cellulose raw material and a process of pulverizing and dispersing it.
  • the content of carboxyl groups to be introduced into CSNF is preferably 0.1 mmol/g or more and 5.0 mmol/g or less, more preferably 0.5 mmol/g or more and 2.0 mmol/g or less.
  • the amount of carboxyl groups is less than 0.1 mmol/g, there is a tendency that it becomes difficult to make the cellulose fine and uniformly disperse it, because the solvent penetration action due to the osmotic pressure effect does not work between the cellulose microfibrils. be.
  • the cellulose microfibrils become low-molecular-weight due to a side reaction accompanying the chemical treatment, so that highly crystalline, rigid, micronized cellulose 1 fibers cannot be obtained, and O/W type. It tends to be difficult to use as an emulsion stabilizer.
  • the counter ion of the carboxyl group of CSNF obtained by the step of oxidizing the cellulose raw material, filtering and washing, and finely dispersing into a dispersion liquid is sodium ion, It becomes metal ions such as alkali metals such as potassium ions and lithium ions, and alkaline earth metals such as magnesium ions and calcium ions.
  • the counterion of the carboxy group of CSNF is a metal ion, the surface of CSNF is highly hydrophilic.
  • the amount of metal ions bound to CSNF is preferably 0.1 mmol/g or more and 5.0 mmol/g or less, and is preferably 0.5 mmol/g or more and 2.0 mmol/g or less. more preferred.
  • the binding amount of metal ions is less than 0.1 mmol/g, the solvent penetration action due to the osmotic pressure effect does not work between the cellulose microfibrils, making it difficult to make the cellulose fine and uniformly disperse it.
  • the cellulose microfibrils become low-molecular-weight due to side reactions accompanying the chemical treatment, making it impossible to obtain a highly crystalline, rigid, micronized cellulose 1-fiber structure. It tends to be difficult to use as a stabilizer for O/W emulsions.
  • the metal ion content can be examined by various analytical methods. For example, the EPMA method using an electron beam microanalyzer, X-ray fluorescence analysis, and elemental analysis such as ICP emission spectrometry can be easily examined. can.
  • an organic onium compound/amine is added to the micronized cellulose dispersion obtained in the first step and stirred to convert the micronized cellulose 1 contained in the micronized cellulose dispersion into organic onium ions/ammonium ions.
  • the anionic functional group of the micronized cellulose 1 can easily be paired. Ions can be exchanged.
  • the cationic substance as the counter ion of the anionic functional group is a metal ion such as sodium ion.
  • Micronized cellulose 1 can be obtained by filtering and washing TEMPO-oxidized cellulose with metal ions as counter ions, suspending it in dispersion solvent 4, and subjecting it to physical fibrillation.
  • preparation of micronized cellulose to which organic onium cations/ammonium ions 7a are bound by conventional methods is complicated.
  • an acid is added to the oxidation reaction solution to adjust the inside of the system to be acidic, and the carboxylic acid is separated by filtration.
  • /amine is added and stirred to bind organic onium ions/ammonium ions 7a, and this suspension is subjected to a physical defibration treatment to form fine particles having anionic functional groups to which organic onium ions/ammonium ions 7a are bound.
  • a modified cellulose 1 is prepared.
  • organic onium ions/ammonium ions 7a are produced by a simple method of adding an organic onium compound/amine in the second step to the micronized cellulose 1 obtained in the first step and stirring.
  • An ionically bound micronized cellulose dispersion containing bound micronized cellulose 1 can be obtained. Hydrophobicity is thereby imparted to a part of the micronized cellulose 1 .
  • the anionic finely divided cellulose 1 to which an organic onium compound/amine is added may form a salt with a cationic substance as a counterion, but may not contain a cationic substance.
  • the cationic substance of the counter ion preferably has a stronger ionization tendency than the organic onium ion/ammonium ion 7a. The stronger the ionization tendency of the cationic substance, the more efficiently counter ion substitution proceeds, which is preferable.
  • the cationic substance of the counter ion is preferably, for example, an alkali metal ion such as sodium ion, potassium ion or lithium ion, or a metal ion such as alkaline earth metal ion such as magnesium ion or calcium ion. Even after binding organic onium ions/ammonium ions 7a to the anionic functional groups of at least a portion of the micronized cellulose 1, the cationic substance may remain in a portion of the anionic functional groups. Although the amount of the cationic substance remaining in the anionic functional group is not particularly limited, it is 0.95 equivalent or less, preferably 0.90 equivalent or less, more preferably 0.95 equivalent or less, relative to the anionic functional group of the micronized cellulose 1.
  • the content of cationic substances in the micronized cellulose 1 can be examined by various analytical methods.
  • the cationic substance is a metal
  • an EPMA method using an electron beam microanalyzer, elemental analysis by fluorescent X-ray analysis, and the like can be exemplified as simple methods.
  • the micronized cellulose 1 is repeatedly washed under acidic conditions, then purified by repeatedly washing with pure water, and then subjected to the physical defibration treatment described above again. I can give an example.
  • the amount of the organic ammonium compound/amine added to the micronized cellulose dispersion is preferably 0.01 equivalent or more and 2 equivalents or less with respect to the anionic functional group contained in the micronized cellulose 1.
  • the amount added is 0.02 equivalent or more and 1.8 equivalent or less
  • the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, and the particle size is uniform. It is preferable because the composite particles 5 can be obtained with a high yield.
  • the amount of the organic onium compound/amine added is less than 0.01 equivalent, the hydrophobization of the surface of the micronized cellulose 1 is not sufficient, and the particle size tends to vary, and the yield may decrease.
  • the amount exceeds 2 equivalents excessive addition of the organic onium compound/amine may cause decomposition of the micronized cellulose 1 or decrease in affinity to the dispersion medium, which is not preferable.
  • the average binding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 is 0.01 equivalent or more, preferably 0.05 equivalent or more, preferably 0.8 equivalent or less, and preferably 0.8 equivalent or less with respect to the anionic functional group. is 0.50 equivalents or less, more preferably 0.30 equivalents or less.
  • the average bonding amount of the organic onium ion/ammonium ion 7a is within this range, the dispersibility and stability of the micronized cellulose 1 are improved.
  • the average binding amount (equivalent) of the organic onium ion/ammonium ion 7a is defined by A being the average binding amount (mmol/g) of the organic onium ion/ammonium ion 7a per micronized cellulose, and the amount of anionic functional groups per micronized cellulose. If (mmol/g) is B, it can be calculated as A/B.
  • A the average binding amount of the organic onium ion/ammonium ion 7a per micronized cellulose
  • B it can be calculated as A/B.
  • the average binding amount is 0.01 equivalent or more and 0.8 equivalent or less, the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, the particle size is small, This is preferable because uniform composite particles 5 can be obtained at a high yield.
  • the binding amount of the organic onium ion/ammonium ion 7a is less than 0.01 equivalent, the surface of the micronized cellulose 1 is not sufficiently hydrophobized, and the particle size tends to vary, resulting in a decrease in yield. On the other hand, if it exceeds 0.8 equivalents, the organic onium ion/ammonium ion 7a may decompose the micronized cellulose 1 or lower the affinity for the dispersion medium, which is not preferable.
  • the type of organic onium compound/amine may be one type, or two or more types may be mixed and used.
  • organic oniums or amines having different structures of hydroxyl groups or hydrocarbon groups may be mixed and used.
  • the hydrocarbon group may be linear or branched.
  • Water is suitable as the dispersion solvent 4 when the organic onium compound/amine is added to the micronized cellulose 1, and it is preferable that the water content is 50% or more.
  • the proportion of micronized cellulose 1 in the dispersion is preferably 0.1% or more and less than 10%. If it is less than 0.1%, the amount of the solvent becomes excessive when defibrating the cellulose raw material in the first step, which impairs productivity, which is not preferable.
  • the yield of the composite particles 5 decreases, and the particle diameter tends to vary. If it is 10% or more, the suspension will rapidly thicken as the cellulose raw material is defibrated, making it difficult to perform a uniform fibrillation treatment, which is not preferable. Moreover, since the viscosity of the dispersion liquid of micronized cellulose 1 increases, it becomes difficult to form an O/W emulsion in the third step.
  • the method of obtaining the micronized cellulose dispersion containing the micronized cellulose 1 to which the organic onium ions/ammonium ions 7a are bound is not particularly limited. may be added to the dispersion and stirred to obtain the dispersion.
  • concentration of the organic onium compound/amine in the aqueous solution in which the organic onium compound/amine is dissolved is not particularly limited, it is preferably 0.01M or more and 5.0M or less.
  • the pH of the dispersion liquid of micronized cellulose 1 to which the organic onium compound/amine is added is not particularly limited, and is preferably 4 or more and 12 or less, more preferably 6 or more and 10 or less.
  • the anionic functional groups of the micronized cellulose 1 are likely to be ionized, and the osmotic pressure effect makes it easier for the solvent to penetrate between the fibers of the micronized cellulose 1, increasing the dispersion stability of the micronized cellulose 1. .
  • the pH after adding the organic onium compound/amine to the micronized cellulose 1 is preferably 4 or more and 12 or less.
  • the anionic functional group of the micronized cellulose 1 is ionized, so that the solvent easily penetrates between the fibers of the micronized cellulose 1 due to the osmotic pressure effect, and the micronized cellulose 1 is dispersed. Increased stability.
  • the pH is less than 4, the dispersibility of the micronized cellulose 1 is lowered.
  • the pH exceeds 12
  • the anionic finely divided cellulose 1 undergoes a peeling reaction or alkali hydrolysis, resulting in a low molecular weight, and terminal aldehydes and double bond formation accelerate yellowing of the dispersion. , unfavorable.
  • the temperature at which the organic onium compound/amine is added to the micronized cellulose 1 and stirred is not particularly limited, it is preferably 4°C or higher and 80°C or lower, more preferably 10°C or higher and 70°C or lower. If the temperature is less than 4° C., the exchange efficiency of the counter ion will be poor. If the temperature exceeds 80° C., the cellulose tends to have a low molecular weight and the fibrous structure of the highly crystalline rigid micronized cellulose 1 collapses, making it difficult to use it as a stabilizer for O/W emulsions.
  • the stirring time can be appropriately set in consideration of the temperature, the desired amount of anionic functional groups, etc., and is not particularly limited, but is usually about 10 minutes to 5 hours.
  • the organic onium compound in this embodiment has a cation structure of the structural formula shown in Chemical formula 1.
  • M is a nitrogen atom, a phosphorus atom, a hydrogen atom, or a sulfur atom
  • R1, R2, R3, and R4 are a hydrogen atom, a hydrocarbon group, or a hydrocarbon group containing a hetero atom.
  • the organic onium compound is ammonia.
  • R1, R2, R3, and R4 are hydrogen atoms, it is a primary amine, two when it is a secondary amine, one when it is a tertiary amine, and zero when it is a quaternary amine, Both are organic onium compounds in the present embodiment.
  • hydrocarbon groups containing heteroatoms include alkyl groups, alkylene groups, oxyalkylene groups, aralkyl groups, aryl groups, and aromatic groups.
  • R1, R2, R3 and R4 may form a ring.
  • Examples of quaternary ammonium compounds in which M is a nitrogen atom in the above structural formula include tetraethylammonium hydroxide (TEAH), tetraethylammonium chloride, tetrabutylammonium hydroxide (TBAH), tetrabutylammonium chloride, didecyl dimethylammonium chloride, lauryltrimethylammonium chloride, dilauryldimethylchloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, cetyltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, coconut amine.
  • TEAH tetraethylammonium hydroxide
  • TBAH tetrabutylammonium hydroxide
  • didecyl dimethylammonium chloride lauryltrimethylammonium chloride, dilauryldimethylchloride, ste
  • Examples of quaternary phosphonium compounds in which M is a phosphorus atom in the above structural formula include tetramethylphosphonium hydroxide, tetraethylphosphonium hydroxide, tetrapropylphosphonium hydroxide, tetrabutylphosphonium hydroxide, and benzyltrimethylphosphonium hydroxide. , benzyltriethylphosphonium hydroxide, hexadecyltrimethylphosphonium hydroxide and the like.
  • the primary amine, secondary amine, and tertiary amine in the present embodiment have the structures shown in formulas (1), (2), and (3) of chemical formula 2, respectively.
  • the structures when these are ionized to become ammonium ions with a cationic structure are (1)', (2)', and (3)', respectively.
  • (1)' is a primary ammonium ion
  • (2)' is a secondary ammonium ion
  • (3)' is a tertiary ammonium ion.
  • R1 to R6 are either a hydrocarbon group or a hydrocarbon group containing a heteroatom.
  • Primary amine, secondary amine and tertiary amine include methylamine, ethylamine, propylamine, butylamine, n-octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, hexylamine and 2-ethylamine.
  • PEG- NH 2 polyethylene glycolamine
  • EO/PO ethylene oxide/propylene oxide
  • the counter ion of the cationic structure of the organic onium compound/amine is not particularly limited.
  • the counter ion of the cation structure of the organic onium compound include nitrate ion, sulfate ion, hydroxide ion, chloride ion, bromide ion, iodide ion and the like.
  • the use of a salt organic onium compound in which the counter ion of the cationic structure is a chloride ion or a bromide ion can suppress the increase in pH even when added to the finely divided cellulose dispersion, making it easy to control the pH.
  • the organic onium compound may be a hydrate.
  • an inorganic alkali containing a metal salt such as an alkali metal or an alkaline earth metal may be added in addition to the organic onium compound.
  • the micronized cellulose 1 obtained by adding an organic onium compound/amine to the micronized cellulose 1 and combining the organic onium ion/ammonium ion 7a has a higher dispersion than when an inorganic alkali having a metal ion as a counter ion is used. good dispersion stability. This is because the use of an organic onium compound/amine has a larger ion diameter of the counter ion of the anionic site of the micronized cellulose 1, and thus has a greater effect of separating the micronized cellulose 1 from each other in the dispersion solvent 4. it is conceivable that.
  • the dispersion contains an organic onium compound/amine
  • the viscosity and thixotropy of the dispersion can be reduced compared to inorganic alkali, which is advantageous in terms of ease of emulsification in the third step described below and subsequent handling.
  • the micronized cellulose 1 interacting with the organic onium compound/amine through ionic bonds is reduced in hydrophilicity due to the steric repulsion or hydrophobizing action based on the organic onium ion/ammonium ion 7a.
  • the affinity of the liquid core particle precursor 2 to the emulsion droplets is increased in the third step, which will be described later, and the stability of the droplets 6 is improved.
  • the obtained micronized cellulose dispersion may contain other ingredients other than cellulose and the ingredients used for adjusting the pH, if necessary, within a range that does not impair the effects of the present invention.
  • Other components are not particularly limited, and can be appropriately selected from known additives according to the use of the composite particles 5 and the like.
  • organic metal compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic acicular minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, UV absorbers, stabilizers, magnetic powders, orientation accelerators, plasticizers, cross-linking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxidation things, etc.
  • organic metal compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic acicular minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, UV absorbers, stabilizers, magnetic powders, orientation accelerators, plasticizers, cross-linking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxide
  • the third step is a step of stabilizing the liquid droplets 6 containing the core particle precursor 2 as an emulsion in the dispersion liquid of the micronized cellulose to which the organic onium ions/ammonium ions 7a are bonded obtained in the second step. .
  • a liquid oil phase (dispersed phase) containing the core particle precursor 2 is added to the dispersion (aqueous phase, dispersed phase) obtained in the second step, and as shown in FIG.
  • Droplets 6 containing the core particle precursor 2 are dispersed in the dispersion liquid.
  • the surfaces of the droplets 6 are coated with the micronized cellulose 1, and an O/W emulsion stabilized by the coating layer 10 is produced.
  • micronized cellulose 1 obtained in the second step to which the organic onium ions/ammonium ions 7a are bonded and at least a portion of the surface of which is hydrophobized even if a wide variety of core particle precursors 2 are used,
  • the micronized cellulose 1 is stably adsorbed on the droplets 6, and a stable O/W emulsion can be obtained.
  • the method for producing an O/W emulsion is not particularly limited, but general emulsification treatments such as various homogenizer treatments and mechanical stirring treatments can be used.
  • Mechanical treatments such as ball mills, roll mills, cutter mills, planetary mills, jet mills, attritors, grinders, juicer mixers, homomixers, ultrasonic homogenizers, nanogenizers, underwater counter-impingement, and paint shakers. Also, a plurality of mechanical treatments may be used in combination.
  • a polymerizable monomer is added to the micronized cellulose dispersion obtained in the first step to form a mixed solvent, and the tip of the ultrasonic homogenizer is inserted into the mixed solvent to perform ultrasonic treatment.
  • the processing conditions of the ultrasonic homogenizer are not particularly limited, but, for example, the frequency is generally 20 kHz or higher and the output is generally 10 W/cm 2 or higher.
  • the treatment time is also not particularly limited, but is usually about 10 seconds to 1 hour.
  • the droplets 6 containing the core particle precursor 2 are dispersed in the dispersion liquid, emulsification progresses, and further, the finely divided cellulose is selectively formed at the liquid/liquid interface between the droplets 6 and the dispersion liquid.
  • adsorbing 1 droplets 6 are coated with micronized cellulose 1 to form a stable structure as an O/W emulsion.
  • Such an emulsion stabilized by adsorption of a solid substance to the liquid/liquid interface is academically called a "Pickering emulsion".
  • cellulose has hydrophilic sites derived from hydroxyl groups and hydrophobic sites derived from hydrocarbon groups in its molecular structure. Since it exhibits amphiphilicity from , it is thought that it adsorbs to the liquid/liquid interface between the hydrophobic monomer and the hydrophilic solvent due to the amphiphilicity.
  • the O/W emulsion structure can be confirmed by optical microscope observation.
  • the particle size of the O/W emulsion is not particularly limited, it is usually preferably about 0.1 ⁇ m to 1000 ⁇ m.
  • the average particle size of the emulsion is preferably 0.1 ⁇ m or more and 100 ⁇ m or less, more preferably 0.1 ⁇ m or more and 50 ⁇ m or less, and still more preferably 0.1 ⁇ m or more and 20 ⁇ m or less.
  • the average particle size of the emulsion is not particularly limited, but can be calculated by measuring the particle size of 100 emulsion droplets with an optical microscope and averaging them.
  • the thickness of the coating layer 10 formed on the surface layer of the droplet 6 is not particularly limited, but is usually about 3 nm to 1000 nm.
  • the thickness of the coating layer 10 can be measured using, for example, a cryo-TEM (Transmission Electron Microscope).
  • the liquid oil phase (dispersed phase) containing the core particle precursor 2 may contain the core particle precursor 2 and form an O/W emulsion as the droplets 6. In order to stably form , it is preferably incompatible with the dispersion liquid of the micronized cellulose 1 and hydrophobic.
  • the core particle precursor 2 is a precursor that solidifies to form the core particles 3 by chemical change or physicochemical change.
  • the compound having polymerizability includes a monomer having a polymerizable functional group (polymerizable monomer), an oligomer having a polymerizable functional group (polymerizable oligomer), and a polymer having a polymerizable functional group (polymerizable polymer). and the like, which can form a solid polymer by a polymerization reaction.
  • Melting polymers include those that are thermoplastic polymers that melt into a liquid state by heating and undergo a phase transition to become a solid at room temperature.
  • the (C) dissolved polymer includes a non-curable polymer that dissolves into a liquid state with a solvent and becomes solid at room temperature when the solvent is removed.
  • the polymerizable monomer has at least one polymerizable functional group.
  • a polymerizable monomer having one polymerizable functional group is also called a monofunctional monomer.
  • a polymerizable monomer having two or more polymerizable functional groups is also called a polyfunctional monomer.
  • the type of the polymerizable monomer is not particularly limited, examples thereof include (meth)acrylic monomers and vinyl monomers.
  • a polymerizable monomer having a cyclic ether structure such as an epoxy group or an oxetane structure (eg, ⁇ -caprolactone, etc.) can also be used. Note that the notation of "(meth)acrylate” includes both "acrylate” and "methacrylate”.
  • Examples of monofunctional (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl ( meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (me
  • bifunctional (meth)acrylic monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate.
  • acrylate ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate)
  • Di(meth)acrylates such as (meth)acrylates, neopentyl glycol di(meth)acrylates, ethoxylated neopentyl glycol di(meth)acrylates, tripropylene glycol di(meth)acrylates, and neopentyl glycol hydroxypivalate di(meth)acrylates meth)acrylate and the like.
  • trifunctional or higher (meth)acrylic monomers examples include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-2-hydroxy Ethyl isocyanurate tri(meth)acrylate, tri(meth)acrylate such as glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, etc.
  • Trifunctional (meth)acrylate compounds pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta ( Trifunctional or higher polyfunctional (meth)acrylate compounds such as meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane hexa(meth)acrylate, and some of these (meth)acrylates are alkyl groups or ⁇ - Polyfunctional (meth)acrylate compounds substituted with caprolactone, and the like.
  • monofunctional vinyl-based monomers liquids which are incompatible with water at room temperature, such as vinyl ether-based, vinyl ester-based, aromatic vinyl-based, particularly styrene and styrene-based monomers, are preferred.
  • (meth)acrylates among monofunctional vinyl-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl ( meth)acrylate, alkyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl ( meth)acrylate, allyl (meth)
  • the monofunctional aromatic vinyl monomers include styrene, ⁇ -methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, isopropenyltoluene, isobutyltoluene, tert-butylstyrene, vinyl naphthalene, vinylbiphenyl, 1,1-diphenylethylene, and the like.
  • Polyfunctional vinyl-based monomers include polyfunctional groups having unsaturated bonds such as divinylbenzene. Liquids that are incompatible with water at room temperature are preferred.
  • polyfunctional vinyl-based monomers specifically include (1) divinyls such as divinylbenzene, 1,2,4-trivinylbenzene and 1,3,5-trivinylbenzene, and (2) ethylene glycol.
  • Dimethacrylate diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexamethylene glycol dimethacrylate, neopentyl glycol dimethacrylate Dimethacrylates such as methacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis(4-methacryloxydiethoxyphenyl)propane, (3) trimethylolpropane trimethacrylate, triethylolethane trimethacrylate, etc.
  • trimethacrylates (4) ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-dipropylene glycol diacrylate, 1,4-dibutylene glycol diacrylate, 1,6 - hexylene glycol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, 2,2-bis(4-acryloxypropoxyphenyl)propane, 2,2-bis(4-acryloxydi (5) triacrylates such as trimethylolpropane triacrylate and triethylolethane triacrylate; (6) tetraacrylates such as tetramethylolmethane tetraacrylate; Examples include tetramethylenebis(ethyl fumarate), hexamethylenebis(acrylamide), triallyl cyanurate and triallyl isocyanurate.
  • functional styrene monomers include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis(vinylphenyl)methane, bis(vinylphenyl)ethane, bis(vinyl phenyl)propane, bis(vinylphenyl)butane, and the like.
  • polyether resins polyester resins, polyurethane resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having at least one or more polymerizable functional groups
  • the material is not particularly limited.
  • the various polymerizable monomers described above may be used alone, or two or more of them may be used in combination.
  • the thermoplastic polymer preferably has a melting point of 40°C or higher and 80°C or lower. If the melting point is lower than 40° C., it becomes difficult to maintain the shape as a solid at room temperature, which is not preferable because the usage environment is extremely restricted. On the other hand, if the melting point exceeds 80° C., it is difficult to maintain the molten state in the finely divided cellulose dispersion in terms of the production process, which is not preferred. More preferably, the melting point is 45°C or higher and 75°C or lower. Also, the melt flow rate (MFR) above the melting point is preferably 10 or more. If the MFR is less than 10, the emulsification treatment described above requires a large amount of emulsifying energy, which is not preferable.
  • MFR melt flow rate
  • the non-curable polymer is one that dissolves in a solvent other than water and has a liquid state.
  • the solvent for dissolving the non-curable polymer preferably has a water solubility of 20 g or more and 2000 g or less per 1 L of water at 20°C. If it is less than 20 g, the affinity between the droplets containing the solvent and the micronized cellulose 1 is low, and the emulsion stabilizing effect of the micronized cellulose 1 is reduced. On the other hand, if it is more than 2000 g, the droplets cannot maintain their shape due to the high diffusion speed of the solvent in the finely divided cellulose dispersion. As a result, the droplet covering effect of the micronized cellulose 1 is impaired.
  • thermoplastic polymer and the non-curable polymer are not limited as long as the functions of the present embodiment are not impaired.
  • the various monofunctional monomers described above polymers starting from polymerizable monomers having a cyclic ether structure such as an epoxy group or an oxetane structure, or polyether resins, polyester resins, polyurethane resins, epoxy resins, and alkyd resins. , spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and the like can be used.
  • Biodegradable polymers can also be used as thermoplastic polymers and non-curable polymers.
  • the biodegradable polymer is not particularly limited as long as it is biodegradable and does not dissolve in water.
  • cellulose acetate derivatives such as cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate.
  • polysaccharides such as chitin and chitosan
  • polylactic acids such as polylactic acid and copolymers of lactic acid and other hydroxycarboxylic acids
  • dibasic acid polyesters such as polybutylene succinate, polyethylene succinate and polybutylene adipate
  • Polycaprolactones such as polycaprolactone, copolymers of caprolactone and hydroxycarboxylic acid
  • polyhydroxybutyrates such as polyhydroxybutyrate, copolymers of polyhydroxybutyrate and hydroxycarboxylic acid, polyhydroxybutyric acid
  • poly Examples include aliphatic polyesters such as copolymers of hydroxybutyric acid and other hydroxycarboxylic acids, polyamino acids, polyester polycarbonates, and natural resins such as rosin. These compounds can be used alone or in combination of two or more.
  • the weight ratio of the micronized cellulose dispersion (aqueous phase, continuous phase) and the core particle precursor 2 in the third step is not particularly limited. is preferably 1 part by mass or more and 50 parts by mass or less. If the amount of the core particle precursor 2 is 1 part by mass or less, the yield of the composite particles 5 will decrease.
  • a polymerization initiator may be contained in advance.
  • general polymerization initiators include radical initiators such as organic peroxides and azo polymerization initiators.
  • organic peroxides examples include peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxycarbonates, and peroxyesters.
  • ADVN, AIBN, etc. can be illustrated as an azo polymerization initiator.
  • AIBN 2,2-azobis(isobutyronitrile)
  • AMBN 2,2-azobis(2-methylbutyronitrile)
  • ADVN 2,2-azobis(2,4-dimethylvaleronitrile)
  • ACVA 4,4-azobis(4-cyanovaleric acid)
  • ACVA 1, 1-azobis(1-acetoxy-1-phenylethane
  • 2,2- Azobis(2-methylamidinopropane) dihydrochloride 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis[2-methyl-N-(2-hydroxyethyl) propion
  • the droplets of the emulsion contain the polymerization initiator when the O/W emulsion is formed.
  • the polymerization reaction for polymerizing the monomer inside the droplets of the emulsion proceeds more easily.
  • the weight ratio of the polymerizable monomer and the polymerization initiator in the third step is not particularly limited, it is usually preferable that the polymerization initiator is 0.1 parts by mass or more with respect to 100 parts by mass of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 parts by mass, the polymerization reaction does not proceed sufficiently, and the yield of the composite particles 5 decreases, which is not preferable.
  • a method of obtaining a molten polymer by melting a thermoplastic polymer for example, a polymer that is solid at room temperature is melted to make it liquid. While the molten polymer is mechanically treated with an ultrasonic homogenizer or the like as described above, the dispersion of micronized cellulose 1 obtained in the second step is heated to a temperature at which the molten state of the polymer can be maintained.
  • the addition of molten polymer preferably stabilizes the molten polymer droplets as an O/W emulsion in the dispersion.
  • the solvent for dissolving the non-curable polymer to prepare the dissolved polymer is not particularly limited, but it is preferable to use an organic solvent in order to stabilize the emulsion.
  • an organic solvent for example, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), isophorone, cellosolve acetate, isophorone, Solvesso 100, trichlene, hexane, chloroform, dichloromethane, dichloroethane, isooctane, nonane, etc. are used. be able to.
  • the mass ratio of the non-curable polymer and solvent is not particularly limited.
  • the weight of the solvent is preferably 0.005 parts by mass or more and 900 parts by mass or less, more preferably 0.1 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the non-curable polymer. is preferred.
  • the liquid oil phase (dispersed phase) containing the core particle precursor 2 may contain functional components other than the polymerization initiator in advance.
  • functional components include solvents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxides, and the like.
  • the functional component can be contained inside the core particle of the manufactured composite particles 5, and the function can be expressed according to the application. It becomes possible.
  • the fourth step is a step of solidifying the core particle precursor 2 to solidify the droplets 6 to obtain the composite particles 5 in which the core particles 3 are coated with the coating layer 10. be.
  • the method for solidifying the core particle precursor 2 is not particularly limited.
  • a compound having polymerizability is used as the core particle precursor 2, it can be solidified by polymerizing by heating, ultraviolet irradiation, or the like.
  • a molten polymer is used as the core particle precursor 2
  • the molten polymer can be cooled and solidified.
  • a dissolved polymer is used as the core particle precursor 2
  • the polymer can be solidified by removing the solvent by a method of diffusing the solvent inside the droplets 6 into the dispersion solvent 4 or a method of evaporating the solvent.
  • the polymerization method is not particularly limited, and can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator used.
  • An example of the polymerization method is a suspension polymerization method.
  • a specific suspension polymerization method is also not particularly limited, and a known method can be used.
  • the core particle precursor 2 can be solidified by heating the O/W emulsion obtained in the third step while stirring.
  • the stirring method is also not particularly limited, and a known method can be used. Specifically, a disper or a stirrer can be used. In some cases, it can be solidified only by heat treatment without stirring.
  • the temperature conditions during heating can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator, and may be, for example, 20° C. or higher and 150° C. or lower. If the temperature is less than 20°C, the polymerization reaction rate may decrease, and if it exceeds 150°C, the micronized cellulose 1 may be denatured.
  • the time for the polymerization reaction can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator, and may be, for example, about 1 hour to 24 hours.
  • the polymerization reaction may be carried out by ultraviolet irradiation treatment, which is a type of electromagnetic waves. In addition to electromagnetic waves, particle beams such as electron beams may be used.
  • thermoplastic polymer When using a thermoplastic polymer, it is solidified by phase transition of the molten polymer. Cooling is the typical method of phase transition. At this time, the degree of crystallinity of the thermoplastic polymer can be controlled by controlling the cooling rate. Specific cooling methods include a method of diffusing in water or ice water, a method of contacting with a coolant such as liquid nitrogen, and a method of standing to cool.
  • a method for removing the solvent is not particularly limited, and examples thereof include a heating method, a pressure reduction method, an electromagnetic wave irradiation method, and a combination thereof.
  • the method for evaporating the solvent of the dissolved polymer is to evaporate and remove the solvent by heating and/or drying under reduced pressure.
  • the boiling point of the solvent is lower than that of water, it is possible to selectively remove the solvent.
  • the solvent can be efficiently removed by heating under reduced pressure conditions.
  • the heating temperature is preferably 20° C. or higher and 100° C. or lower, and the pressure is preferably 600 mHg or higher and 750 mmHg or lower.
  • the method of diffusing the solvent of the dissolved polymer into the dispersion solvent 4 is, specifically, to diffuse the solvent inside the droplets 6 into the dispersion solvent 4 by adding another solvent or salt to the O/W emulsion liquid. .
  • the solvent with low solubility in the dispersion solvent 4 diffuses into the aqueous phase of the dispersion solvent 4 over time, the dissolved polymer can be precipitated and solidified as particles.
  • substantially spherical composite particles 5 in which the polymer-containing core particles 3 are coated with the micronized cellulose 1 are obtained.
  • organic onium cations/ammonium ions 7a are bound to at least part of the micronized cellulose 1 existing on the surface.
  • the particle size of the composite particles 5 is relatively uniform, and the degree of uniformity is high.
  • the dispersion liquid is in a state in which the composite particles 5, a large amount of water, and the finely divided cellulose 1 that is not integrated with the core particles 3 and are free are mixed.
  • the recovery/purification method for extracting only the composite particles 5 from the dispersion liquid include washing by centrifugation and washing by filtration.
  • a known method can be used as a washing method by centrifugation.
  • the composite particles 5 in the dispersion are sedimented by centrifugation, the supernatant is removed, and the operation of redispersing in a mixed solvent of water and methanol is repeated, and the residual solvent is finally removed from the sediment obtained by centrifugation.
  • Composite particles 5 can be recovered by removing them.
  • a known method can also be used for filtration and washing. For example, suction filtration is repeated with water and methanol using a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.1 ⁇ m, and finally the composite particles 5 are obtained by removing the residual solvent from the paste remaining on the membrane filter. can be recovered.
  • the method for removing the residual solvent is not particularly limited, and it can be carried out by air drying or heat drying in an oven.
  • the dry solid matter containing the composite particles 5 does not form a film or an aggregate, but is obtained as a fine powder.
  • the core particles 3 and the micronized cellulose 1 are inseparably bonded, and even after recovery and purification of only the composite particles 5, the micronized cellulose 1 and the core particles 3 cannot be separated. Therefore, the state of covering the core particles 3 with the micronized cellulose 1 is maintained.
  • the yield of the composite particles 5 obtained by the above steps is preferably 30% or more, more preferably 50% or more, still more preferably 60% or more.
  • the yield can be calculated as follows: Weight (g) of dry solid matter of composite particles 5/weight (g) of resin of core particle precursor 2 used for production ⁇ 100.
  • the fifth step is to remove the organic onium cation/ammonium ion 7a from the composite particles 5 obtained.
  • the fifth step is performed after the fourth step as necessary, and may be omitted if unnecessary in view of the use of the composite particles 5 and the like.
  • part of the micronized cellulose 1 has organic onium cations/ammonium ions 7a as counterions.
  • organic onium cation/ammonium ion 7a is not preferable in relation to the use of the composite particles 5, or when a cationic substance different from the organic onium cation/ammonium ion 7a is desired to be bound to the micronized cellulose 1 as an ionic bond.
  • a fifth step may be performed to remove the organic onium cation/ammonium ion 7a.
  • Ion exchange is mentioned as a method for removing the organic onium cation/ammonium ion 7a.
  • the organic onium cations/ammonium ions 7a can be removed by dispersing the composite particles 5 having the organic onium cations/ammonium ions 7a in an aqueous solution containing an acidic compound and then washing with pure water. After removing the organic onium cations/ammonium ions 7a, a desired cationic compound may be added to bond a cationic substance different from the organic onium cations/ammonium ions 7a to the anionic functional groups of the micronized cellulose 1 by ionic bonding. I do not care.
  • the composite particles 5 according to this embodiment have the micronized cellulose 1 present as the coating layer 10 on the surface. Moreover, the composite particles 5 have high biocompatibility and good dispersion stability derived from the micronized cellulose 1 .
  • the core particles 3 can be formed from a wide variety of resins, and composite particles that can be used in a wide variety of applications can be easily produced. obtained by the method. For example, thermoplastic composite particles, which have been difficult to produce in the past, can be easily produced.
  • micronized cellulose 1 acquires hydrophobicity due to the organic onium cations/ammonium ions 7a, thereby becoming amphiphilic.
  • the yield of the composite particles 5 is remarkably improved, the particle size distribution is made uniform, and the material is excellent.
  • the dry solid of the composite particles 5 exhibits the material properties of the micronized cellulose 1, but is obtained as a fine powder, and since there is no agglomeration of the particles, it can be easily dispersed again in a solvent. be. Since the micronized cellulose 1 and the core particles 3 are inseparably bonded, stable dispersion derived from the characteristics of the micronized cellulose 1 is exhibited even after redispersion.
  • the method for producing the composite particles 5 according to the present embodiment can easily obtain particles exhibiting the properties of the micronized cellulose 1 in a dry state and in a circulable state. Therefore, effects such as low environmental load, reduction in transportation costs, reduction in spoilage risk, improvement in addition efficiency as an additive, and improvement in kneading efficiency with hydrophobic resin can be expected.
  • Example 1> (First step: step of obtaining a micronized cellulose dispersion) (TEMPO oxidation of wood cellulose) 70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution prepared by dissolving 0.7 g of TEMPO and 7 g of sodium bromide in 350 g of distilled water was added and cooled to 20°C. 450 g of an aqueous sodium hypochlorite solution having a density of 1.15 g/mL and 2 mol/L was added dropwise to initiate an oxidation reaction.
  • TEMPO oxidation of wood cellulose 70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution prepared by dissolving 0.7 g of TEMPO and 7 g of sodium bromide in 350 g of distilled water was added and cooled to 20°C.
  • the temperature in the system was always kept at 20° C., and the decrease in pH during the reaction was kept at pH 10 by adding a 0.5N sodium hydroxide aqueous solution.
  • a 0.5N sodium hydroxide aqueous solution When the total added amount of sodium hydroxide reached 3.0 mmol/g with respect to the mass of cellulose, about 100 mL of ethanol was added to terminate the reaction. Thereafter, filtration and washing with distilled water were repeated using a glass filter to obtain TEMPO oxidized cellulose (oxidized cellulose, oxidized pulp).
  • the carboxy group content of the oxidized cellulose before dispersion treatment was calculated by the following method. 0.2 g of oxidized cellulose in terms of dry mass was placed in a beaker, and 80 mL of ion-exchanged water was added.
  • the crystallinity of TEMPO-oxidized cellulose was calculated.
  • TEMPO oxidized cellulose using a sample horizontal multipurpose X-ray diffractometer (trade name: Ultima III, manufactured by Rigaku), X-ray output: (40 kv, 40 mA), X in the range of 5 ° ⁇ 2 ⁇ ⁇ 35 ° A line diffraction pattern was measured. Since the obtained X-ray diffraction pattern is derived from the cellulose type I crystal structure, the crystallinity of the TEMPO-oxidized cellulose was calculated using the following formula (2) by the method shown below.
  • the number average axis diameter of the long axis of the micronized cellulose was obtained by measuring the long axis diameter (maximum diameter) of 100 fibers from an image observed with an atomic force microscope and calculating the average value. By similarly measuring the short axis diameter of the fiber, the number average axial diameter of the short axis of the micronized cellulose was calculated.
  • the rheology of a dispersion containing 0.5% by mass of micronized cellulose was measured using a rheometer (trade name: AR2000ex, manufactured by TA Instruments) with a cone plate having an inclination angle of 1°.
  • the temperature of the measurement part was adjusted to 25° C., and the shear viscosity was continuously measured at a shear rate of 0.01 s ⁇ 1 to 1000 s ⁇ 1 .
  • the results are shown in FIG.
  • the micronized cellulose dispersion exhibited thixotropic properties.
  • Table 1 shows shear viscosities at shear rates of 10 s ⁇ 1 and 100 s ⁇ 1 .
  • the micronized cellulose aqueous dispersion exhibited high transparency. Further, the number average short axis diameter of the micronized cellulose (TEMPO-oxidized CNF) contained in the micronized cellulose aqueous dispersion was 3 nm, and the number average long axis diameter was 831 nm. Furthermore, FIG. 4 shows the results of steady-state viscoelasticity measurement using a rheometer. As is clear from FIG. 4, the micronized cellulose dispersion exhibited thixotropic properties.
  • Step of producing O/W type emulsion 10 g of monofunctional methacrylate and isobornyl methacrylate (hereinafter also referred to as “IB-X”), which are polymerizable monomers, were used as the core particle precursor, and 2,2-azobis-2,4, which is a polymerization initiator, was used.
  • IB-X monofunctional methacrylate and isobornyl methacrylate
  • 2,2-azobis-2,4 which is a polymerization initiator
  • ADVN dimethylvaleronitrile
  • the total amount of the IB-X/ADVN mixed solution was added to 40 g of micronized cellulose dispersion having a concentration of 1%.
  • the IB-X/ADVN mixed solution and the dispersion separated into two phases with high transparency.
  • the shaft of an ultrasonic homogenizer was inserted from the liquid surface of the upper phase in the liquid mixture in which the two phases were separated, and ultrasonic homogenizer treatment was performed for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W.
  • the mixture After being treated with an ultrasonic homogenizer, the mixture turned into a cloudy emulsion.
  • one drop of the mixed liquid was dropped on a slide glass, sealed with a cover glass, and observed with an optical microscope, a large number of IB-X emulsion droplets of several ⁇ m or less were observed, and the dispersion was stabilized as an O/W emulsion. The situation was confirmed.
  • the supernatant was removed by decantation to collect the sediment, which was then repeatedly washed with pure water and methanol using a PTFE membrane filter with a pore size of 0.1 ⁇ m.
  • the composite particles thus purified and recovered were re-dispersed in pure water at a concentration of 1%, and the particle size was measured using a particle shape image analyzer (PITA-04, Seishin Enterprise Co., Ltd.). It was 1.3 ⁇ m.
  • PITA-04 Seishin Enterprise Co., Ltd.
  • FIGS. 5A and 5B SEM images of the dry powder are shown in FIGS. 5A and 5B.
  • FIG. 5A is an image at a magnification of 20,000 times
  • FIG. 5B is an image at a magnification of 50,000 times.
  • the polymerization reaction was carried out using the O/W type emulsion droplet as a template, so that a large number of spherical composite particles 5 derived from the shape of the emulsion droplet were obtained, and the particle size was uniform. It can be seen from FIG. 5A that once higher. As shown in FIG.
  • FIG. 5B shows an image of the composite particles after repeated filtration and washing. Therefore, in the composite particles 5 of the present example, the core particles 3 and the micronized cellulose 1 are bonded and inseparable. was shown to be in (Particle size distribution of composite particles)
  • FIG. 8 shows the results of measuring the particle size distribution of the dry powder with a particle size distribution analyzer LS-13320 manufactured by Beckman Coulter. The particle size distribution of Example 1, with an average particle size (median value) of 1.3 ⁇ m, was almost within the range of 10 ⁇ m or less, showing good agreement with the SEM image.
  • Example 2 Composite particles according to Examples 2 to 8 were produced in the same manner as in Example 1, except that the following organic onium compounds were used in place of the organic onium compound tetrabutylammonium chloride (TBACl) as the alkaline species. .
  • TBACl organic onium compound tetrabutylammonium chloride
  • Example 2 Tetrabutylammonium Bromide (TBABr)
  • Example 3 Tetrabutylammonium Hydroxide (TBAH)
  • Example 4 Tetramethylammonium Hydroxide (TMAH)
  • DMSA Dimethylstearylamine
  • Example 7 Stearylamine
  • Example 9 to 12 Composites according to Examples 9 to 12 were prepared in the same manner as in Example 3, except that the following amount of tetrabutylammonium hydroxide (TBAH), an organic onium compound, was added to the carboxy groups of the micronized cellulose. Particles were produced.
  • TBAH tetrabutylammonium hydroxide
  • Example 10 0.05 equivalents
  • Example 11 0.25 equivalents
  • Example 12 0.50 equivalents
  • Example 13 Composite particles according to Examples 13 to 15 were produced in the same manner as in Example 1, except that the following monomers/oligomers were used as core particle precursors instead of IB-X.
  • Example 13 Monofunctional Acrylate Isobornyl Acrylate (IB-XA)
  • Example 14 Monofunctional Vinyl Monomer p-Methylstyrene (p-MeSt)
  • Example 15 Difunctional Urethane Acrylate Oligomer (UA4200)
  • Example 16 Polycaprolactone (PCL, molecular weight 10,000) was used as a core particle precursor.
  • PCL polycaprolactone
  • a 20% MEK solution of PCL was added to the micronized cellulose dispersion. After heating this dispersion to 75° C. and subjecting it to an ultrasonic homogenizer treatment to form an O/W emulsion, in the fourth step, instead of performing a polymerization reaction, the droplets were solidified by cooling with ice water.
  • a composite particle according to Example 16 was produced under the same conditions as in Example 1 except for the above.
  • Example 17 The same as in Example 1, except that instead of TEMPO-oxidized CNF, CM-CNF obtained by performing the carboxymethylation (hereinafter also referred to as "CM-conversion") treatment described in Patent Document 2 was used. Composite particles according to Example 17 were produced under the conditions.
  • Example 18 In Example 1, instead of TEMPO oxidation, a phosphorylated CNF dispersion obtained by performing a phosphorylation treatment according to Non-Patent Document 1 cited as a prior art document was used. Composite particles according to Example 18 were produced under the same conditions as in .
  • the purified and collected composite particles were air-dried, and further vacuum-dried at room temperature of 25° C. for 24 hours to obtain dry powder.
  • the resulting dry powder was analyzed by X-ray photoelectron spectroscopy (XPS), nitrogen origin derived from TBACl was not detected, confirming that organic onium cations were removed.
  • the dry powder was again added to pure water and sonicated, showing good redispersion. All examples were subjected to the above treatment, and removal of organic onium cations and satisfactory redispersion were confirmed.
  • the fifth step was not performed.
  • Table 2 summarizes the contents of Examples and Comparative Examples.
  • Table 3 shows the evaluation results of Examples and Comparative Examples. Evaluation items and criteria are as follows.
  • emulsion stability After the O/W type emulsion obtained in the third step was allowed to stand for 24 hours, the O/W type emulsion was observed with an optical microscope, and the diameter of 100 droplets was measured. It was taken as the droplet diameter. If the emulsion stability is low, the droplet size becomes large due to instability such as creaming, aggregation, and coalescence of droplets. Emulsion stability was evaluated as follows. ⁇ (good): The maximum droplet diameter is 50 ⁇ m or less. x (bad): the maximum droplet size exceeds 50 ⁇ m. (Possibility of preparing composite particles) Whether composite particles can be produced was evaluated as follows.
  • ⁇ Yield of composite particles The yield of the composite particles was calculated by multiplying the weight (g) of the obtained composite particles/the resin weight (g) of the core particle precursor used for production ⁇ 100.
  • ⁇ Average particle size of composite particles The average particle size of the composite particles was determined using a particle shape image analyzer (PITA-04). When coarse resin lumps were present, they were removed and measured.
  • - Particle Size Uniformity of Composite Particles The particle size of 100 particles was measured by optical microscope observation, and the difference between the maximum and minimum particle sizes was calculated as the particle size range. The particle size uniformity of the composite particles was evaluated in the following two stages. ⁇ (good): The particle size range is 50 ⁇ m or less. ⁇ (bad): The particle size range exceeds 50 ⁇ m.
  • FIGS. 6A and 6B show SEM images of composite particles according to Example 10.
  • FIG. 6A The magnifications of FIGS. 6A and 6B are the same as in FIGS. 5A and 5B, respectively.
  • FIG. 6A many fine spherical particles with a size of several ⁇ m or less are produced as a whole, and as shown in FIG. It can be seen that Also, from the particle size distribution shown in FIG. 8, it can be confirmed that fine particles are produced in Example 10 as a whole.
  • various core precursors and core particles other than IB-X such as IB-XA, pMe-St, UA4200, and PCL, have high yields and particle diameters. Uniform composite particles could be obtained.
  • examples 17 and 18 even when using finely divided cellulose having various anionic functional groups other than TEMPO oxidation, such as CM and phosphate esterification, organic onium compounds/amines are added afterward. By a simple addition method, the surface of the micronized cellulose was hydrophobized, and composite particles with a uniform particle size could be obtained at a high yield.
  • Composite particles could also be obtained in Comparative Examples 1 to 7, but as shown in Table 3, the emulsion stability was low and the yield was lower than in Examples 1 to 18. It was large and the uniformity of particle size was low.
  • 7A and 7B show SEM images of dry powder of composite particles according to Comparative Example 2.
  • FIG. The magnifications of FIGS. 7A and 7B are similar to FIGS. 5A and 5B, respectively.
  • FIG. 7A in Comparative Example 1, a large number of coarsened composite particles exist and the particle size distribution is not uniform. In the coarsened composite particles, as shown in FIG. 7B, most of the surface of the core particles was exposed, and only a small amount of finely divided cellulose was bound.
  • Comparative Example 2 When the composite particles of Comparative Examples 1 to 8 were observed with an optical microscope, the maximum particle size was 50 ⁇ m or more, and there was a possibility that the cell of the particle size distribution meter PITA-04 was clogged, so particle size distribution measurement could not be performed. I didn't.
  • Comparative Example 2 coarse particles were removed, and the particle size distribution was evaluated using a particle size distribution meter. That is, the particle size distribution of Comparative Example 2 shown in FIG. 8 is the particle size distribution after removing coarse particles. As shown in FIG. 8, the particle size of Comparative Example 2 tended to be larger than those of Examples 1 and 10, and the variation in particle size was also large.
  • the composite particles according to the present invention have favorable effects from the viewpoint of industrial implementation, such as improving the addition efficiency as an additive and the efficiency of kneading with a resin, and contributing to cost reduction from the viewpoint of improving transportation efficiency and preventing spoilage. can get.
  • the composite particles can be used for coloring materials, adsorbents, cosmetic pigments, sustained-release materials, deodorants, antibacterial medical materials, personal care products, etc.
  • Antibacterial products for supplies, packaging materials, dye-sensitized solar cells, photoelectric conversion materials, photothermal conversion materials, heat shielding materials, optical filters, Raman enhancement elements, image display elements, magnetic powders, catalyst carriers, drug delivery systems, etc. can be applied to

Abstract

The method for producing a composite particle comprises: a first step of fibrillating a cellulose starting material in a dispersion solvent to obtain a microfine-sized cellulose dispersion in which microfine-sized cellulose is dispersed; a second step of adding an organic onium compound or an amine to the microfine-sized cellulose dispersion to obtain a microfine-sized cellulose dispersion containing an ion-bonded microfine-sized cellulose in which an organic onium ion or ammonium ion is bound; a third step of stabilizing, as an emulsion in the ion-bonded microfine-sized cellulose dispersion, droplets containing a core particle precursor; and a fourth step of solidifying the core particle precursor to convert same into a core particle and obtain a composite particle in which the core particle is coated with a microfine-sized cellulose that is inseparably bonded to the core particle.

Description

複合粒子の製造方法および複合粒子Composite particle manufacturing method and composite particle
　本発明は、微細化セルロースとコア粒子から成る複合粒子の製造方法および複合粒子に関する。
　本願は、２０２１年６月２８日に日本に出願された特願２０２１－１０６６７５号に基づき優先権を主張し、その内容をここに援用する。 TECHNICAL FIELD The present invention relates to a method for producing composite particles composed of micronized cellulose and core particles, and the composite particles.
This application claims priority based on Japanese Patent Application No. 2021-106675 filed in Japan on June 28, 2021, the contents of which are incorporated herein.
　近年、木材中のセルロース繊維を、その構造の少なくとも一辺がナノメートルオーダーになるまで微細化し、新規な機能性材料として利用しようとする試みが活発に行われている。 In recent years, attempts have been actively made to refine cellulose fibers in wood until at least one side of the structure is on the order of nanometers, and to use them as new functional materials.
　例えば、特許文献１には、木材セルロースに対しブレンダーやグラインダーによる機械処理を繰り返すことで、微細化セルロース繊維、すなわちセルロースナノファイバー（以下、「ＣＮＦ」とも称する。）が得られることが開示されている。この方法で得られるＣＮＦは、短軸径が１０～５０ｎｍ、長軸径が１μｍ～１０ｍｍであると記載されている。このＣＮＦは、鋼鉄の１／５の軽さで５倍以上の強さを誇り、２５０ｍ２／ｇ以上の膨大な比表面積を有することから、樹脂強化用フィラーや吸着剤としての利用が期待されている。 For example, Patent Document 1 discloses that fine cellulose fibers, that is, cellulose nanofibers (hereinafter also referred to as "CNF") can be obtained by repeatedly mechanically treating wood cellulose with a blender or a grinder. there is CNFs obtained by this method are described as having a minor axis diameter of 10 to 50 nm and a major axis diameter of 1 μm to 10 mm. This CNF is one-fifth the weight of steel and more than five times stronger than steel, and has a huge specific surface area of 250 m 2 /g or more. ing.
　ＣＮＦの製造において、木材中のセルロース繊維を微細化しやすいように予め化学処理したのち、家庭用ミキサー程度の低エネルギー機械処理により微細化する試みが活発に行われている。上記化学処理の方法は特に限定されないが、セルロース繊維にイオン性官能基を導入して微細化しやすくする方法が好ましい。セルロース繊維にイオン性官能基が導入されることによってセルロースミクロフィブリル構造間に浸透圧効果で溶媒が浸入しやすくなり、セルロース原料の微細化に要するエネルギーを大幅に減少することができる。 In the production of CNF, attempts are actively being made to chemically treat the cellulose fibers in the wood in advance so that they can be easily refined, and then to refine them using a low-energy mechanical process similar to that of a household mixer. The method of chemical treatment is not particularly limited, but a method of introducing an ionic functional group into the cellulose fiber to make it easier to refine is preferable. By introducing an ionic functional group into the cellulose fibers, the osmotic pressure effect makes it easier for the solvent to penetrate into the cellulose microfibril structure, and the energy required for refining the cellulose raw material can be greatly reduced.
　上記イオン性官能基の導入方法は特に限定されないが、例えば非特許文献１には、リン酸エステル化処理を用いて、セルロースの微細繊維表面を選択的にリン酸エステル化処理する方法が開示されている。特許文献２には、高濃度アルカリ水溶液中でセルロースをモノクロロ酢酸又はモノクロロ酢酸ナトリウムと反応させることによりカルボキシメチル化することが開示されている。オートクレーブ中でガス化したマレイン酸やフタル酸等の無水カルボン酸系化合物とセルロースとを直接反応させてカルボキシ基を導入してもよい。 Although the method for introducing the ionic functional group is not particularly limited, for example, Non-Patent Document 1 discloses a method of selectively phosphating the surface of cellulose fine fibers using phosphating. ing. Patent Literature 2 discloses carboxymethylation by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a highly concentrated alkaline aqueous solution. A carboxyl group may be introduced by directly reacting a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave with cellulose.
　また、比較的安定なＮ－オキシル化合物である２，２，６，６－テトラメチルピペリジニル－１－オキシラジカル（ＴＥＭＰＯ）を触媒として用い、セルロースの微細繊維表面を選択的に酸化する方法も報告されている（例えば、特許文献３参照。）。ＴＥＭＰＯを触媒として用いる酸化反応（ＴＥＭＰＯ酸化反応）は、水系、常温、常圧で進行する環境調和型の化学改質が可能であり、木材中のセルロースに適用した場合、結晶内部には反応が進行せず、結晶表面のセルロース分子鎖が持つアルコール性１級炭素のみを選択的にカルボキシ基へと変換することができる。 Also, a method of selectively oxidizing the surface of cellulose fine fibers using 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO), which is a relatively stable N-oxyl compound, as a catalyst. has also been reported (see, for example, Patent Document 3). The oxidation reaction using TEMPO as a catalyst (TEMPO oxidation reaction) is an environmentally friendly chemical modification that progresses in an aqueous system at normal temperature and pressure. When applied to cellulose in wood, there is no reaction inside the crystal. It does not proceed, and only alcoholic primary carbons possessed by cellulose molecular chains on the crystal surface can be selectively converted into carboxyl groups.
　ＴＥＭＰＯ酸化によって選択的に結晶表面に導入されたカルボキシ基同士の電離に伴う浸透圧効果により、溶媒中で一本一本のセルロースミクロフィブリル単位に分散させた、セルロースシングルナノファイバー（以下ＣＳＮＦとも称する）が得られる。ＣＳＮＦは表面のカルボキシ基に由来した高い分散安定性を示す。木材からＴＥＭＰＯ酸化反応によって得られる木材由来のＣＳＮＦは、短軸径が３ｎｍ前後、長軸径が数十ｎｍ～数μｍに及ぶ高アスペクト比を有する構造体であり、その水分散液および成形体は高い透明性を有することが報告されている。
　特許文献４には、ＣＳＮＦ分散液を塗布乾燥して得られる積層膜がガスバリア性を有することが記載されている。 Cellulose single nanofibers (hereinafter also referred to as CSNF) dispersed in a solvent into individual cellulose microfibril units due to the osmotic pressure effect associated with the ionization of the carboxy groups selectively introduced to the crystal surface by TEMPO oxidation. ) is obtained. CSNF exhibits high dispersion stability due to surface carboxyl groups. Wood-derived CSNF obtained from wood by TEMPO oxidation reaction is a structure having a high aspect ratio with a short axis diameter of about 3 nm and a long axis diameter of several tens of nm to several μm. has been reported to have high transparency.
Patent Document 4 describes that a laminated film obtained by coating and drying a CSNF dispersion has gas barrier properties.
　特許文献５には、カチオン性を有する微細化セルロースの対イオンとして有機オニウムカチオンを配する表面改質により、有機溶媒中で高度に微細化セルロースが分散した分散液が得られることが記載されている。 Patent Document 5 describes that a dispersion in which highly refined cellulose is dispersed in an organic solvent can be obtained by surface modification in which organic onium cations are arranged as counterions of cationic finely divided cellulose. there is
　微細化セルロースを用いた塗工用組成物の例として、例えば特許文献６には、ＴＥＭＰＯ酸化ＣＮＦを含む水性塗液が記載されている。この水性塗液は良好な塗工性を有し、アンカー層上にコーティングすることによりバリア性を有する積層体を得られることが記載されている。
　特許文献７には、セルロースナノファイバーのアスペクト比の高い繊維同士の絡み合いや増粘特性、カルボキシ基に由来する電荷の影響によりカーボン微粒子を分散安定化させたＴＥＭＰＯ酸化ＣＮＦを含む塗液が開示されている。 As an example of a coating composition using micronized cellulose, for example, Patent Document 6 describes an aqueous coating liquid containing TEMPO-oxidized CNF. It is described that this water-based coating liquid has good coatability, and that a laminate having barrier properties can be obtained by coating it on the anchor layer.
Patent Document 7 discloses a coating liquid containing TEMPO-oxidized CNF in which carbon fine particles are dispersed and stabilized by the influence of the entanglement and thickening properties of cellulose nanofibers with a high aspect ratio, and the charge derived from the carboxy group. ing.
　一方、ＣＮＦの実用化に向けては、得られるＣＮＦ分散液の固形分濃度が０．１～５％程度と低くなってしまうことが課題である。例えば、微細化セルロース分散液を輸送しようとした場合、大量の溶媒とともに輸送するため輸送費がかさみ、事業性に大きく影響する。また、樹脂強化用の添加剤として用いる際にも、固形分濃度が低いことによる添加効率の悪さや、溶媒である水が樹脂と馴染まない場合には複合化が困難となるといった点が問題である。さらに、含水状態で流通させる場合、腐敗の可能性もあるため、冷蔵保管や防腐処理などの対策が必要となり、コスト増加の原因となる場合もある。 On the other hand, for the practical use of CNF, the problem is that the solid content concentration of the obtained CNF dispersion is as low as about 0.1 to 5%. For example, when trying to transport a micronized cellulose dispersion, it is transported together with a large amount of solvent, which increases transportation costs and greatly affects business feasibility. In addition, when used as an additive for strengthening resin, there are problems such as poor addition efficiency due to low solid content concentration and difficulty in compounding when water, which is a solvent, is not compatible with resin. be. Furthermore, when distributed in a water-containing state, there is a possibility of spoilage, so countermeasures such as refrigerated storage and antiseptic treatment are required, which may cause an increase in cost.
　しかしながら、単純に熱乾燥などで微細化セルロース分散液の溶媒を除去してしまうと、微細化セルロース同士が凝集・角質化し、あるいは膜化してしまい、添加剤として使用した際に期待する機能が安定して発現しない場合がある。さらにＣＮＦの固形分濃度が低いため、乾燥による溶媒除去工程自体に多大なエネルギーがかかってしまうことも事業性へのハードルとなる。 However, if the solvent of the micronized cellulose dispersion is simply removed by heat drying, etc., the micronized cellulose will aggregate, keratinize, or form a film, and the expected function will not be stable when used as an additive. and may not appear. Furthermore, since the solid content concentration of CNF is low, a large amount of energy is required for the solvent removal process itself by drying, which is a hurdle to business feasibility.
　このように、ＣＮＦを分散液の状態で取り扱うこと自体が事業性への課題となっており、ＣＮＦを容易に取り扱うことができる新たな態様を提供することが強く望まれている。 In this way, handling CNF in the form of a dispersion has itself become an issue for business feasibility, and it is strongly desired to provide a new mode in which CNF can be handled easily.
　ＣＮＦを容易に取り扱うことができる新たな態様として、特許文献８には、セルロース繊維により構成される被覆層と、被覆層に覆われたポリマーとを含む複合粒子が記載されている。この複合粒子において、セルロース繊維とポリマーとは一体化しているため、ろ過により簡単に分離でき、粉体として流通できる。粉体の再分散性も良好である。 As a new aspect that allows easy handling of CNF, Patent Document 8 describes composite particles containing a coating layer composed of cellulose fibers and a polymer covered with the coating layer. In this composite particle, since the cellulose fiber and the polymer are integrated, they can be easily separated by filtration and distributed as powder. The redispersibility of the powder is also good.
日本国特開２０１０－２１６０２１号公報Japanese Patent Application Laid-Open No. 2010-216021 国際公開第２０１４／０８８０７２号WO2014/088072 日本国特開２００８－００１７２８号公報Japanese Patent Application Laid-Open No. 2008-001728 国際公開第２０１３／０４２６５４号WO2013/042654 日本国特開２０１５－１０１６９４号公報Japanese Patent Application Laid-Open No. 2015-101694 日本国特許第５９２８３３９号公報Japanese Patent No. 5928339 日本国特許第６０２０４５４号公報Japanese Patent No. 6020454 日本国特開２０１９－３８９４９号公報Japanese Patent Application Laid-Open No. 2019-38949
　特許文献８に記載の複合粒子は、上述したようにＣＮＦの特性を発揮する材料として優れているものの、適用できるポリマーの種類に限りがある点で改善の余地がある。
　適用が難しい樹脂材料で複合粒子を形成する場合、収率が著しく低下する、得られる粒子の粒径分布のばらつきが大きくなる、粒子の表面に存在するＣＮＦの量が少ないために材料としてＣＮＦ特性を十分発揮しない等の様々な問題が生じる。 Although the composite particles described in Patent Document 8 are excellent as a material that exhibits the properties of CNF as described above, there is room for improvement in that the types of applicable polymers are limited.
When forming composite particles from a resin material that is difficult to apply, the yield drops significantly, the particle size distribution of the obtained particles increases, and the amount of CNF present on the surface of the particles is small. There are various problems such as not fully demonstrating
　上記事情を踏まえ、本発明は、取り扱い性に優れ、汎用性も高いセルロース繊維の複合粒子およびその製造方法を提供することを目的とする。 Based on the above circumstances, an object of the present invention is to provide composite particles of cellulose fibers that are excellent in handleability and have high versatility, and a method for producing the same.
　本発明の第一の態様は、複合粒子の製造方法である。
　この製造方法は、セルロース原料を分散溶媒中で解繊して、微細化セルロースが分散された微細化セルロース分散液を得る第一工程と、微細化セルロース分散液に、有機オニウム化合物またはアミンを添加して、有機オニウムイオンまたはアンモニウムイオンが結合した微細化セルロースを含むイオン結合微細化セルロース分散液を得る第二工程と、イオン結合微細化セルロース分散液中においてコア粒子前駆体を含む液滴をエマルションとして安定化させる第三工程と、コア粒子前駆体を固体化させてコア粒子とし、コア粒子と不可分に結合した微細化セルロースがコア粒子を被覆した複合粒子を得る第四工程とを備える。 A first aspect of the present invention is a method for producing composite particles.
This production method includes a first step of defibrating a cellulose raw material in a dispersion solvent to obtain a micronized cellulose dispersion in which micronized cellulose is dispersed, and adding an organic onium compound or an amine to the micronized cellulose dispersion. a second step of obtaining an ion-bonded micronized cellulose dispersion containing micronized cellulose bound with organic onium ions or ammonium ions; and a fourth step of solidifying the core particle precursor to form core particles and obtaining composite particles in which the core particles are coated with micronized cellulose that is inseparably bound to the core particles.
　本発明の第二の態様は、少なくとも１種類のポリマーを含むコア粒子と、コア粒子と不可分に結合してコア粒子の表面上に配置された、アニオン性官能基を有する微細化セルロースとを備える複合粒子である。
　この複合粒子においては、微細化セルロースの少なくとも一部に有機オニウムイオンまたはアンモニウムイオンが結合している。 A second aspect of the present invention comprises a core particle comprising at least one polymer, and micronized cellulose having anionic functional groups disposed on the surface of the core particle inseparably bound to the core particle. Composite particles.
In this composite particle, organic onium ions or ammonium ions are bound to at least part of the micronized cellulose.
　本発明によれば、取り扱い性に優れ、汎用性も高いセルロース繊維の複合粒子を提供できる。 According to the present invention, it is possible to provide composite particles of cellulose fibers that are excellent in handleability and have high versatility.
本発明の一実施形態に係る複合粒子の模式図である。1 is a schematic diagram of a composite particle according to one embodiment of the present invention; FIG. 同複合粒子の製造方法の一例を示す図である。It is a figure which shows an example of the manufacturing method of the same composite particle. 実施例に係るセルロースナノファイバーの水分散液について分光透過スペクトルを測定した結果を示すグラフである。4 is a graph showing the results of measuring the spectral transmission spectrum of an aqueous dispersion of cellulose nanofibers according to an example. 同水分散液に対し、レオメーターを用いて定常粘弾性測定を行った結果を示すグラフである。It is a graph which shows the result of having performed steady-state viscoelasticity measurement using the rheometer with respect to the same aqueous dispersion. 実施例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to an example. 実施例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to an example. 実施例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to an example. 実施例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to an example. 比較例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to a comparative example. 比較例に係る複合粒子の走査電子顕微鏡像である。4 is a scanning electron microscope image of composite particles according to a comparative example. 実施例および比較例に係る複合粒子の粒度分布を示すグラフである。4 is a graph showing particle size distributions of composite particles according to Examples and Comparative Examples.
　以下、本発明の一実施形態について、図面を用いて説明する。ただし、以下に説明する各図において相互に対応する部分には同一符号を付し、重複部分においては後述での説明を適宜省略する。また、本実施形態は、本発明の技術的思想を具体化するための構成を例示するものであって、各部の材質、形状、構造、配置、寸法等を下記のものに特定するものでない。本発明の技術的思想は、特許請求の範囲に記載された請求項が規定する技術的範囲内において、種々の変更を加えることができる。 An embodiment of the present invention will be described below with reference to the drawings. However, in each drawing described below, the same reference numerals are given to the parts that correspond to each other, and the description of overlapping parts will be omitted as appropriate. Further, the present embodiment exemplifies the configuration for embodying the technical idea of the present invention, and does not specify the material, shape, structure, arrangement, dimensions, etc. of each part as follows. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.
＜複合粒子＞
　まず、本発明の第一実施形態に係る微細化セルロース／コア粒子の複合粒子について説明する。尚、コア粒子３の一態様は樹脂であり、ポリマーとも称する。
　図１に、本実施形態に係る複合粒子５の模式図を示す。複合粒子５は、コア粒子３と、コア粒子３の表面上に位置する微細化セルロース１とを備える。複合粒子５において、微細化セルロース１はコア粒子３と結合して不可分の状態にある。微細化セルロース１とコア粒子３との結合態様は特に限定されないが、多数の微細化セルロース１がコア粒子３と結合することにより、図１に示すように、コア粒子３の表面に微細化セルロース層からなる被覆層１０を形成していることが好ましい。
　微細化セルロース１の少なくとも一部には、有機オニウムカチオンまたはアミン７ａがカウンターカチオンとして結合している。
　以降の説明において、有機オニウム化合物がイオン化した状態を、「有機オニウムイオン」または「有機オニウムカチオン」と称することがある。また、本明細書において、「アミン」とは、一部またはすべてがイオン化したアンモニウムイオンを含む。
　さらに、以降の説明において、有機オニウム化合物またはアミン、または有機オニウムカチオンまたはアンモニウムイオンのいずれかを、それぞれ「有機オニウム化合物／アミン」、「有機オニウムカチオン（または、有機オニウムイオン）／アンモニウムイオン」と称することがある。 <Composite particles>
First, the composite particles of micronized cellulose/core particles according to the first embodiment of the present invention will be described. One aspect of the core particles 3 is a resin, which is also called a polymer.
FIG. 1 shows a schematic diagram of a composite particle 5 according to this embodiment. Composite particle 5 comprises core particle 3 and micronized cellulose 1 located on the surface of core particle 3 . In the composite particle 5, the micronized cellulose 1 is combined with the core particle 3 and is inseparable. The mode of bonding between the micronized cellulose 1 and the core particles 3 is not particularly limited. It is preferable to form the coating layer 10 which consists of layers.
Organic onium cations or amines 7a are bound to at least part of the micronized cellulose 1 as counter cations.
In the following description, the ionized state of the organic onium compound may be referred to as "organic onium ion" or "organic onium cation". In addition, the term "amine" as used herein includes partially or wholly ionized ammonium ions.
Furthermore, in the following description, either an organic onium compound or an amine, or an organic onium cation or an ammonium ion will be referred to as "organic onium compound/amine" and "organic onium cation (or organic onium ion)/ammonium ion", respectively. sometimes referred to as
　複合粒子５の製造方法について説明する。
　本実施形態の複合粒子５は、アニオン性官能基のカウンターカチオン（対イオン）として有機オニウムイオン／アンモニウムイオン７ａが結合している微細化セルロース１を用いたＯ／Ｗ型ピッカリングエマルションにおいて油滴（油相、油粒子、分散相）として存在するコア粒子前駆体（以下、単に「液滴」とも称する。）を固体化することで得られる。 A method for manufacturing the composite particles 5 will be described.
Composite particles 5 of the present embodiment are produced in an O/W type Pickering emulsion using micronized cellulose 1 to which organic onium ions/ammonium ions 7a are bound as counter cations (counter ions) of anionic functional groups. It is obtained by solidifying a core particle precursor (hereinafter also simply referred to as “droplets”) present as (oil phase, oil particles, dispersed phase).
　コア粒子前駆体は、固体化してコア粒子を形成するものであればよく、例えば、重合性を有する化合物、溶融ポリマー、溶解ポリマーである。コア粒子前駆体の固体化は、様々な方法で行える。例えば、コア粒子前駆体として重合性官能基を有するモノマー（以下、「重合性モノマー」とも称する。）を用いて、重合過程で粒子形成を行う重合造粒法（乳化重合法、懸濁重合法、シード重合法、放射線重合法等）、微小液滴化したポリマー溶液から粒子形成を行う分散造粒法（スプレードライ法、液中硬化法、溶媒蒸発法、相分離法、溶媒分散冷却法等）が挙げられる。
　本実施形態において、「コア粒子前駆体の固体化」とは、（Ａ）重合性モノマー液滴を重合すること、（Ｂ）溶融ポリマー液滴を冷却して固体化すること、（Ｃ）溶解ポリマー液滴から溶媒を除去して固体化すること、のすべてを含む概念である。 The core particle precursor may be any material as long as it solidifies to form a core particle, and is, for example, a polymerizable compound, a molten polymer, or a dissolved polymer. Solidification of the core particle precursor can be accomplished in a variety of ways. For example, a monomer having a polymerizable functional group (hereinafter also referred to as a "polymerizable monomer") is used as a core particle precursor, and a polymerization granulation method (emulsion polymerization method, suspension polymerization method) in which particles are formed in the polymerization process. , seed polymerization method, radiation polymerization method, etc.), dispersion granulation method (spray drying method, liquid curing method, solvent evaporation method, phase separation method, solvent dispersion cooling method, etc.) that forms particles from a polymer solution made into fine droplets. ).
In the present embodiment, "solidifying the core particle precursor" means (A) polymerizing the polymerizable monomer droplets, (B) cooling the molten polymer droplets to solidify them, and (C) dissolving the It is a concept that includes all of solidification by removing the solvent from the polymer droplets.
　連続相（水相）の分散溶媒に分散したコア粒子前駆体を含む液滴の界面に微細化セルロース１が吸着することによって、Ｏ／Ｗ型ピッカリングエマルションが安定化する。安定化状態を維持したままエマルション内部のコア粒子前駆体を固体化することによって、エマルションを鋳型とした複合粒子５を作製できる。ここで、「エマルションの安定化状態」とは、長時間（例えば１２時間）静置してもエマルションの液滴サイズが変化しない状態を意味する。エマルションが不安定であると、一部の液滴同士が時間経過とともに合一することで、液滴の粒度分布が初期に比べて大きい方へ推移したり、粒度分布にばらつきが生じたりし、さらに場合によっては油相と水相の分離が生じる。その結果、得られる複合粒子の収率が減少することや、複合粒子の粒子径が不均一となることがある。
　特に、アニオン性官能基の対イオンとして有機オニウムイオン／アンモニウムイオン７ａが結合している微細化セルロース１を用いることで、多くのコア粒子前駆体にて安定したＯ／Ｗ型ピッカリングエマルションを形成できるため、粒径が小さく均一な複合粒子５を高収率で得ることができる。 The O/W Pickering emulsion is stabilized by adsorption of the micronized cellulose 1 on the interface of droplets containing the core particle precursor dispersed in the dispersion solvent of the continuous phase (aqueous phase). By solidifying the core particle precursor inside the emulsion while maintaining a stable state, composite particles 5 can be produced using the emulsion as a template. Here, the "stabilized state of the emulsion" means a state in which the droplet size of the emulsion does not change even if it is allowed to stand still for a long period of time (for example, 12 hours). If the emulsion is unstable, some of the droplets coalesce over time, causing the particle size distribution of the droplets to shift to a larger size compared to the initial stage, or to cause variations in the particle size distribution. Furthermore, in some cases separation of oil and water phases occurs. As a result, the yield of the composite particles obtained may decrease, and the particle diameters of the composite particles may become non-uniform.
In particular, by using finely divided cellulose 1 in which organic onium ions/ammonium ions 7a are bonded as counter ions of anionic functional groups, a stable O/W type Pickering emulsion is formed with many core particle precursors. Therefore, composite particles 5 having a small particle size and uniformity can be obtained at a high yield.
　コア粒子前駆体を含む液滴の界面に微細化セルロース１が吸着してＯ／Ｗ型ピッカリングエマルションが安定化するメカニズムについては、吸着による界面エネルギーの低下による作用が関係していると考えられている。微細化されサブミクロンオーダーとなった固体粒子である微細化セルロース１は、物理的な力により液滴の界面に吸着され、水相に対してセルロースの障壁を形成する。一度吸着し界面を形成すると、脱着にはより大きなエネルギーが必要になるため、エマルション構造は安定化する。
　微細化セルロース１は両親媒性があり、疎水性を有する液滴に対して微細化セルロース１の疎水性側が吸着し、親水性である分散溶媒に対して微細化セルロース１の親水性側を向けることにより、液滴界面の安定化が向上するといった作用も推察されている。この界面における微細化セルロース１の吸着力は、固体粒子の油相と水相とへの親和性の高さ、つまり微細化セルロース１のコア粒子前駆体に対する親和性と微細化セルロース１の分散溶媒に対する親和性との両方に依存する。 The mechanism by which the micronized cellulose 1 is adsorbed to the interface of the droplet containing the core particle precursor to stabilize the O/W Pickering emulsion is considered to be related to the effect of the decrease in interfacial energy due to adsorption. ing. Micronized cellulose 1, which is solid particles that have been micronized to submicron order, is adsorbed on the interface of droplets by physical force, forming a cellulose barrier against the aqueous phase. Once adsorbed and an interface is formed, the emulsion structure is stabilized because greater energy is required for desorption.
The micronized cellulose 1 has amphipathic properties, and the hydrophobic side of the micronized cellulose 1 is adsorbed to droplets having hydrophobicity, and the hydrophilic side of the micronized cellulose 1 is directed to the hydrophilic dispersion solvent. As a result, the effect of improving the stability of the droplet interface is also presumed. The adsorptive power of the micronized cellulose 1 at this interface is determined by the high affinity of the solid particles for the oil phase and the aqueous phase, that is, the affinity of the micronized cellulose 1 for the core particle precursor and the dispersion solvent of the micronized cellulose 1. depends on both the affinity for
　本実施形態では、微細化セルロース１の少なくとも一部に疎水性を付与することにより、コア前駆体を含む液滴に対する微細化セルロース１の親和性を高め、吸着力を向上させている。これにより多くのコア前駆体を用いて安定したＯ／Ｗ型ピッカリングエマルションを形成でき、高収率で粒径が小さく、粒径が均一な複合粒子５を得ることができる。
　疎水性を付与する方法としては、疎水性付与の効果が高くプロセスコストにおいて有利である点から、有機オニウム化合物／アミンを用い、微細化セルロース１のアニオン性官能基の対イオンを有機オニウムイオン／アンモニウムイオン７ａとする方法が好ましい。アニオン性官能基を有する微細化セルロース１のアニオン性官能基の対イオンを有機オニウムイオン／アンモニウムイオン７ａとする方法としては、アニオン性官能基を有する微細化セルロース１の分散液に有機オニウム化合物／アミンを添加し、しばらく攪拌する方法が挙げられる。この方法を用いることで、従来の方法より短時間で効率よくアニオン性官能基の対イオンを有機オニウムイオン／アンモニウムイオン７ａとすることが可能である。
　少なくとも一部が疎水化された微細化セルロース１を使用して複合粒子５を作製することにより、エマルションの安定性が向上する。その結果、適用できるコア粒子前駆体２の材料の種類が大幅に増え、用途に応じた要求仕様に対応可能な多様な複合粒子５を高収率に、生産性良く作製できる。 In the present embodiment, by imparting hydrophobicity to at least a portion of the micronized cellulose 1, the affinity of the micronized cellulose 1 for droplets containing the core precursor is increased, and the adsorptive power is improved. As a result, a stable O/W-type Pickering emulsion can be formed using a large amount of core precursor, and composite particles 5 having a small particle size and a uniform particle size can be obtained at a high yield.
As a method for imparting hydrophobicity, since the effect of imparting hydrophobicity is high and it is advantageous in terms of process cost, an organic onium compound / amine is used, and the counter ion of the anionic functional group of the finely divided cellulose 1 is an organic onium ion / A method using ammonium ions 7a is preferred. As a method of using organic onium ion/ammonium ion 7a as the counter ion of the anionic functional group of the micronized cellulose 1 having an anionic functional group, an organic onium compound/ A method of adding an amine and stirring for a while is mentioned. By using this method, it is possible to efficiently convert the counter ion of the anionic functional group to the organic onium ion/ammonium ion 7a in a shorter time than the conventional method.
By using the micronized cellulose 1 at least partially hydrophobized to prepare the composite particles 5, the stability of the emulsion is improved. As a result, the types of applicable materials for the core particle precursor 2 are greatly increased, and various composite particles 5 that can meet the required specifications according to the application can be produced at a high yield and with good productivity.
　本実施形態において、コア粒子３と微細化セルロース１との結合状態を示す「不可分」とは、所定の分離操作を行った後であっても、微細化セルロース１とコア粒子３とが分離せず、微細化セルロース１によるコア粒子３の被覆状態が保たれることを意味する。所定の分離操作とは、例えば、複合粒子５を含む分散液を遠心分離処理して上澄みを除去し、さらに溶媒を加えて再分散することで複合粒子５を精製・洗浄する操作、あるいはメンブレンフィルターを用いたろ過洗浄によって繰り返し溶媒による洗浄する操作を繰り返す操作が挙げられる。
　微細化セルロース１によるコア粒子３の被覆状態は、走査型電子顕微鏡（ＳＥＭ）による複合粒子５の表面観察により確認することができる。微細化セルロース１とコア粒子３とが不可分に結合する詳細なメカニズムについては明らかになっていないが、複合粒子５は、微細化セルロース１によって安定化されたＯ／Ｗ型エマルションを鋳型として作製されるため、エマルション内部の液滴に微細化セルロース１が接触した状態で液滴の固体化が進むと、微細化セルロース１の一部が液滴に位置したまま固定化されて、最終的にコア粒子３と微細化セルロース１とが不可分に結合すると考えられる。
　Ｏ／Ｗ型エマルションは、水中油滴型（Ｏｉｌ－ｉｎ－Ｗａｔｅｒ）とも言われ、水を連続相とし、その中に油が油滴（油粒子）として分散しているものである。 In the present embodiment, the term “inseparable” indicating the bonding state between the core particles 3 and the micronized cellulose 1 means that the micronized cellulose 1 and the core particles 3 cannot be separated even after performing a predetermined separation operation. However, it means that the state of covering the core particles 3 with the micronized cellulose 1 is maintained. The predetermined separation operation is, for example, an operation of centrifuging the dispersion containing the composite particles 5 to remove the supernatant, then adding a solvent and redispersing to purify and wash the composite particles 5, or a membrane filter. An operation of repeating the operation of washing with a solvent repeatedly by filtration washing using is mentioned.
The coating state of the core particles 3 with the micronized cellulose 1 can be confirmed by surface observation of the composite particles 5 with a scanning electron microscope (SEM). Although the detailed mechanism by which the micronized cellulose 1 and the core particles 3 are inseparably bonded has not been clarified, the composite particles 5 are produced using an O/W emulsion stabilized by the micronized cellulose 1 as a template. Therefore, when the solidification of the droplet proceeds while the micronized cellulose 1 is in contact with the droplet inside the emulsion, part of the micronized cellulose 1 is fixed while remaining in the droplet, and finally the core It is believed that the particles 3 and micronized cellulose 1 are inseparably bound.
O/W emulsions are also called oil-in-water emulsions, in which water is a continuous phase in which oil is dispersed as oil droplets (oil particles).
　複合粒子５は、微細化セルロース１によって安定化されたＯ／Ｗ型エマルションを鋳型として作製されるため、Ｏ／Ｗ型エマルションに由来した真球に近い形状となることが一つの特徴である。また、安定したＯ／Ｗ型エマルションにより、粒径が均一な複合粒子５を得ることができる。典型的な複合粒子５においては、真球状のコア粒子３の表面に微細化セルロース１を含む被覆層１０が比較的均一な厚みで形成されることが好ましい。 Since the composite particles 5 are produced using an O/W emulsion stabilized by the micronized cellulose 1 as a template, one of their characteristics is that they have a shape close to a true sphere derived from the O/W emulsion. In addition, composite particles 5 having a uniform particle size can be obtained from a stable O/W emulsion. In a typical composite particle 5, it is preferable that the coating layer 10 containing the micronized cellulose 1 is formed on the surface of the spherical core particle 3 with a relatively uniform thickness.
　本実施形態の複合粒子５は、球状であり、特に真球状であることが好ましい。微細化セルロース１により安定したＯ／Ｗ型ピッカリングエマルションが形成し、これにより真球状の複合粒子５を得ることができる。真球度の指標は、円形度から評価することができる。円形度が０．６以上であることが好ましく、０．７以上であることがより好ましく、更に好ましくは０．９以上である。円形度は、画像分析型粒度分布計にて測定した１０００個以上の粒子の円形度の平均値として算出することができる。算出した平均円形度を上記真球度の指標としてもよい。なお、画像上における複合粒子５の面積をＳ、周囲長をＬとしたとき、円形度は、「円形度＝４πＳ／Ｌ２」の式で算出でき、円形度が１に近いほど真球度が高くなる。 The composite particles 5 of the present embodiment are spherical, and preferably spherical. The micronized cellulose 1 forms a stable O/W-type Pickering emulsion, whereby spherical composite particles 5 can be obtained. The index of sphericity can be evaluated from circularity. The degree of circularity is preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.9 or more. The circularity can be calculated as the average circularity of 1000 or more particles measured by an image analysis type particle size distribution meter. The calculated average circularity may be used as an index of the sphericity. In addition, when the area of the composite particle 5 on the image is S and the circumference is L, the circularity can be calculated by the formula “circularity = 4πS/L 2 ”. becomes higher.
　複合粒子５の粒径は、光学顕微鏡観察により確認できる。１００箇所ランダムに測定し、複合粒子５の直径の平均値を取ることで平均粒径を算出できる。算出した平均粒径を複合粒子５の粒径とすればよい。
　平均粒径は、特に限定されないが、０．０１μｍ以上１０００μｍ以下であることが好ましい。平均粒径は、より好ましくは０．０５μｍ以上１００μｍ以下、更に好ましくは０．１０μｍ以上５０μｍ以下である。微細化セルロース１が液－液界面に吸着して安定したピッカリングエマルションを形成することにより、平均粒径が小さな複合粒子５を得ることができる。
　光学顕微鏡により複合粒子５を１００箇所ランダムに測定し、直径の最大値を取ることで複合粒子５の最大粒径を得られる。特に限定されないが、複合粒子５の最大粒径は２００μｍ以下であることが好ましく、より好ましくは１００μｍ以下、更に好ましくは５０μｍ以下である。本実施形態における複合粒子５は、安定したエマルションを鋳型として得られるため、最大粒径が小さくなる。
　また、粒径の測定には、レーザー回折式粒度分布計や画像解析式粒度分布計等の粒度分布計を用いることもできる。 The particle size of the composite particles 5 can be confirmed by optical microscope observation. The average particle size can be calculated by taking the average value of the diameters of the composite particles 5 after randomly measuring 100 locations. The calculated average particle diameter may be used as the particle diameter of the composite particles 5 .
Although the average particle diameter is not particularly limited, it is preferably 0.01 μm or more and 1000 μm or less. The average particle size is more preferably 0.05 μm or more and 100 μm or less, and still more preferably 0.10 μm or more and 50 μm or less. Composite particles 5 having a small average particle size can be obtained by the micronized cellulose 1 adsorbing to the liquid-liquid interface to form a stable Pickering emulsion.
The maximum particle size of the composite particles 5 can be obtained by randomly measuring 100 composite particles 5 with an optical microscope and taking the maximum value of the diameter. Although not particularly limited, the maximum particle size of the composite particles 5 is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. Since the composite particles 5 in the present embodiment can be obtained using a stable emulsion as a template, the maximum particle size is small.
A particle size distribution analyzer such as a laser diffraction particle size distribution analyzer or an image analysis particle size distribution analyzer can also be used to measure the particle size.
　分散安定性の観点から、微細化セルロース１は、コア粒子３表面に被覆層１０を形成することが好ましい。被覆層１０はコア粒子３表面の全面を覆うことが好ましいが、必ずしも全面を覆わなくてもよい。微細化セルロース１で構成される被覆層１０の厚みは特に限定されないが、３ｎｍ以上１０００ｎｍ以下であることが好ましい。
　被覆層１０の平均厚みは、複合粒子５を包埋樹脂で固定した樹脂片をミクロトームで切削してＳＥＭ観察を行い、画像中の複合粒子５の断面像における被覆層１０の厚みを画像上で１００箇所ランダムに測定し、その算術平均値を算出することで得られる。
　被覆層１０の厚みが均一であることも複合粒子５の一つの特徴である。被覆層１０の厚みの値の変動係数（上述した１００箇所からランダム抽出した３０箇所の標準偏差）は０．５以下となることが好ましく、０．４以下となることがより好ましい。 From the viewpoint of dispersion stability, the micronized cellulose 1 preferably forms a coating layer 10 on the surface of the core particles 3 . The coating layer 10 preferably covers the entire surface of the core particle 3, but does not necessarily have to cover the entire surface. Although the thickness of the coating layer 10 composed of the micronized cellulose 1 is not particularly limited, it is preferably 3 nm or more and 1000 nm or less.
The average thickness of the coating layer 10 is obtained by cutting a resin piece in which the composite particles 5 are fixed with the embedding resin with a microtome and performing SEM observation. It is obtained by randomly measuring 100 points and calculating the arithmetic mean value.
Another feature of the composite particles 5 is that the coating layer 10 has a uniform thickness. The coefficient of variation of the value of the thickness of the coating layer 10 (the standard deviation of 30 points randomly extracted from the 100 points described above) is preferably 0.5 or less, more preferably 0.4 or less.
　本実施形態における微細化セルロース１は、セルロース、セルロース誘導体からなる数平均短軸径が１ｎｍ以上１０００ｎｍ以下のファイバーであり、例えばセルロースナノファイバー（ＣＮＦ）が挙げられる。ＣＮＦは、木材等から得られるセルロース原料を極細繊維に粉砕して得ることができる微細化セルロース１であり、安全で生分解性を有する。 The micronized cellulose 1 in the present embodiment is a fiber made of cellulose or a cellulose derivative and having a number average minor axis diameter of 1 nm or more and 1000 nm or less, such as cellulose nanofiber (CNF). CNF is micronized cellulose 1 that can be obtained by pulverizing a cellulose raw material obtained from wood or the like into ultrafine fibers, and is safe and biodegradable.
　さらに、微細化セルロース１は、ミクロフィブリル構造由来の繊維形状であることが好ましい。具体的には、微細化セルロース１は繊維状であって、数平均短軸径が１ｎｍ以上１０００ｎｍ以下、数平均長軸径が５０ｎｍ以上であり、かつ数平均長軸径が数平均短軸径の５倍以上であることが好ましい。また、微細化セルロース１の結晶化度は５０％以上であることが好ましい。微細化セルロース１の結晶構造は、セルロースＩ型であることが好ましい。 Further, the micronized cellulose 1 preferably has a fibrous shape derived from a microfibril structure. Specifically, the micronized cellulose 1 is fibrous, has a number average minor axis diameter of 1 nm or more and 1000 nm or less, a number average major axis diameter of 50 nm or more, and a number average minor axis diameter of is preferably 5 times or more. Moreover, the crystallinity of the micronized cellulose 1 is preferably 50% or more. The crystal structure of the micronized cellulose 1 is preferably cellulose I type.
　本実施形態の微細化セルロース１の結晶表面にはアニオン性官能基を有することが好ましい。アニオン性官能基としては、特に限定されないが、例えば、カルボキシ基、リン酸基、スルホ基が挙げられる。中でも、カルボキシ基やリン酸基が好ましく、セルロース結晶表面への選択的な導入のしやすさから、カルボキシ基が好ましい。 The crystal surface of the micronized cellulose 1 of the present embodiment preferably has an anionic functional group. Examples of the anionic functional group include, but are not particularly limited to, a carboxy group, a phosphate group, and a sulfo group. Among them, a carboxy group and a phosphate group are preferred, and a carboxy group is preferred because of ease of selective introduction to the cellulose crystal surface.
　本実施形態における微細化セルロース１は特に限定されないが、結晶表面にアニオン性官能基を有しており、当該アニオン性官能基の含有量が、微細化セルロースあたり０．１ｍｍｏｌ／ｇ以上５．０ｍｍｏｌ／ｇ以下であることが好ましい。より好ましくは０．５ｍｍｏｌ／ｇ以上２．０ｍｍｏｌ／ｇ以下である。０．１ｍｍｏｌ／ｇ未満であると、エマルションの安定性が悪くなることがあり、粒子径分布が広くなってしまう。また、５．０ｍｍｏｌ／ｇを超えると安定して複合粒子５を作製することが難しくなることがある。 Although the micronized cellulose 1 in the present embodiment is not particularly limited, it has an anionic functional group on the crystal surface, and the content of the anionic functional group is 0.1 mmol/g or more and 5.0 mmol per micronized cellulose. /g or less. More preferably, it is 0.5 mmol/g or more and 2.0 mmol/g or less. If it is less than 0.1 mmol/g, the stability of the emulsion may deteriorate, resulting in a wide particle size distribution. Moreover, if it exceeds 5.0 mmol/g, it may become difficult to stably produce the composite particles 5 .
　また、本実施形態における複合粒子５に結合した微細化セルロース１の表面側のアニオン性官能基の量は、複合粒子あたり０．０１μｍоｌ／ｇ以上であることが好ましく、より好ましくは０．１０μｍоｌ／ｇ以上であり、１００μｍоｌ／ｇ以下であることが好ましく、より好ましくは５０μｍоｌ／ｇ以下であり、更に好ましくは１０μｍоｌ／ｇ以下である。０．０１μｍоｌ／ｇ未満であるとエマルション安定性が悪く、粒子径分布が広くなってしまうことがある。また、１００μｍоｌ／ｇを超えると安定して複合粒子５を作製することが難しくなることがある。 Further, the amount of anionic functional groups on the surface side of the micronized cellulose 1 bonded to the composite particles 5 in the present embodiment is preferably 0.01 μmol/g or more per composite particle, more preferably 0.10 μmol/g. g or more and preferably 100 μmol/g or less, more preferably 50 μmol/g or less, and even more preferably 10 μmol/g or less. If it is less than 0.01 μmol/g, the emulsion stability may be poor and the particle size distribution may become wide. Moreover, if it exceeds 100 μmol/g, it may become difficult to stably produce the composite particles 5 .
　微細化セルロース１や、複合粒子５に結合した微細化セルロース１の表面側におけるアニオン性官能基量は、特に限定されないが、電気伝導度滴定により測定できる。試料をビーカーに採り、イオン交換水中に分散させ、０．０１ｍｏｌ／Ｌ塩化ナトリウム水溶液を加え、攪拌しながら、０．１ｍｏｌ／Ｌ塩酸を加えて、全体がｐＨ２となるように調整し、自動滴定装置（商品名：ＡＵＴ－７０１、東亜ディーケーケー社製）を用いて、０．１ｍｏｌ／Ｌ水酸化ナトリウム水溶液を０．０５ｍＬ／３０秒で注入し、３０秒毎の電導度とｐＨ値を測定し、ｐＨ１１まで測定を続ける。得られた電導度曲線から、水酸化ナトリウムの滴定量を求め、アニオン性官能基の含有量を算出することができる。 The amount of anionic functional groups on the micronized cellulose 1 and on the surface side of the micronized cellulose 1 bound to the composite particles 5 is not particularly limited, but can be measured by electrical conductivity titration. Take a sample in a beaker, disperse it in ion-exchanged water, add 0.01 mol/L sodium chloride aqueous solution, add 0.1 mol/L hydrochloric acid while stirring, adjust the pH to 2 as a whole, and perform automatic titration. Using a device (trade name: AUT-701, manufactured by Toa DKK Co., Ltd.), 0.1 mol/L sodium hydroxide aqueous solution was injected at 0.05 mL/30 seconds, and the conductivity and pH value were measured every 30 seconds. , the measurement is continued until pH 11. From the obtained conductivity curve, the content of the anionic functional group can be calculated by determining the titration amount of sodium hydroxide.
　微細化セルロース１における有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、エマルション安定性の観点から微細化セルロースあたり、好ましくは０．０２ｍｍｏｌ／ｇ以上であり、より好ましくは０．２ｍｍｏｌ／ｇ以上であり、好ましくは３ｍｍｏｌ／ｇ以下であり、より好ましくは２．５ｍｍｏｌ／ｇ以下であり、更に好ましくは２ｍｍｏｌ／ｇ以下である。
　任意の２種以上の有機オニウムイオン／アンモニウムイオン７ａが同時に微細化セルロース１に導入されていてもよく、この場合、有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、導入されている修飾基の合計量が前記範囲内であることが好ましい。有機オニウムイオン／アンモニウムイオン７ａの平均結合量（ｍｍｏｌ／ｇ）は公知の方法で測定できる。例えば、滴定やＩＲ測定等により算出できる。 The average bonding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 is preferably 0.02 mmol/g or more, more preferably 0.2 mmol/g or more per micronized cellulose from the viewpoint of emulsion stability. Yes, preferably 3 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2 mmol/g or less.
Any two or more organic onium ions/ammonium ions 7a may be introduced into the micronized cellulose 1 at the same time. It is preferable that the total amount is within the above range. The average binding amount (mmol/g) of organic onium ion/ammonium ion 7a can be measured by a known method. For example, it can be calculated by titration, IR measurement, or the like.
　本実施形態に使用する微細化セルロース１における有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、アニオン性官能基に対して０．０１当量以上であることが好ましく、より好ましくは０．０５当量以上であり、０．８当量以下であることが好ましく、より好ましくは０．５０当量以下、さらに好ましくは０．３０当量以下である。
　平均結合量が０．０１当量以上０．８当量以下であると、十分に微細化セルロース１の表面を疎水化することができ、安定したＯ／Ｗ型エマルションを形成でき、粒径が小さく、均一な複合粒子５を高収率に得ることができるため、好ましい。有機オニウムイオン／アンモニウムイオン７ａの結合量が０．０１当量未満であると、微細化セルロース１の表面の疎水化が十分ではなく、粒径にばらつきが生じやすく、収率が下がることもある。一方、０．８当量を超えると、有機オニウムイオン／アンモニウムイオン７ａにより微細化セルロース１の分解や分散媒への親和性低下が生じる場合があり、好ましくない。
　有機オニウムイオン／アンモニウムイオン７ａの平均結合量（当量）は、微細化セルロースあたりの有機オニウムイオン／アンモニウムイオン７ａの平均結合量（ｍｍоｌ／ｇ）をＡ、微細化セルロースあたりのアニオン性官能基量（ｍｍоｌ／ｇ）をＢとすると、Ａ／Ｂにて計算することができる。 The average binding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 used in the present embodiment is preferably 0.01 equivalent or more, more preferably 0.05 equivalent or more with respect to the anionic functional group. and is preferably 0.8 equivalents or less, more preferably 0.50 equivalents or less, and still more preferably 0.30 equivalents or less.
When the average binding amount is 0.01 equivalent or more and 0.8 equivalent or less, the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, the particle size is small, This is preferable because uniform composite particles 5 can be obtained at a high yield. If the binding amount of the organic onium ion/ammonium ion 7a is less than 0.01 equivalent, the surface of the micronized cellulose 1 is not sufficiently hydrophobized, and the particle size tends to vary, resulting in a decrease in yield. On the other hand, if it exceeds 0.8 equivalents, the organic onium ion/ammonium ion 7a may decompose the micronized cellulose 1 or lower the affinity for the dispersion medium, which is not preferable.
The average binding amount (equivalent) of the organic onium ion/ammonium ion 7a is defined by A being the average binding amount (mmol/g) of the organic onium ion/ammonium ion 7a per micronized cellulose, and the amount of anionic functional groups per micronized cellulose. If (mmol/g) is B, it can be calculated as A/B.
　複合粒子５の微細化セルロース１の表面側に結合した有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、エマルション安定性の観点から複合粒子あたり、好ましくは０．０１μｍоｌ／ｇ以上であり、より好ましくは０．１μｍоｌ／ｇ以上であり、好ましくは１００μｍоｌ／ｇ以下であり、より好ましくは５０μｍоｌ／ｇ以下であり、更に好ましくは１０μｍоｌ／ｇ以下である。有機オニウムイオン／アンモニウムイオン７ａの平均結合量がこの範囲であると、複合粒子５の分散性が良好となる。任意の２種以上の有機オニウムイオン／アンモニウムイオン７ａが同時に微細化セルロース１に導入されていてもよく、この場合、有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、導入されている修飾基の合計量が前記範囲内であることが好ましい。有機オニウムイオン／アンモニウムイオン７ａの平均結合量（μｍоｌ／ｇ）は公知の方法で測定できる。
　例えば、塩酸等の酸により複合粒子５を洗浄することにより、複合粒子５から有機オニウムイオン／アンモニウムイオン７ａを分離し、液体クロマトグラフィー、滴定、ＩＲ測定等により算出できる。 The average binding amount of organic onium ions/ammonium ions 7a bound to the surface side of the micronized cellulose 1 of the composite particles 5 is preferably 0.01 μmol/g or more per composite particle, more preferably 0.01 μmol/g or more, from the viewpoint of emulsion stability. is 0.1 μmol/g or more, preferably 100 μmol/g or less, more preferably 50 μmol/g or less, still more preferably 10 μmol/g or less. When the average bonding amount of organic onium ions/ammonium ions 7a is within this range, the composite particles 5 have good dispersibility. Any two or more organic onium ions/ammonium ions 7a may be introduced into the micronized cellulose 1 at the same time. It is preferable that the total amount is within the above range. The average binding amount (μmol/g) of organic onium ion/ammonium ion 7a can be measured by a known method.
For example, by washing the composite particles 5 with an acid such as hydrochloric acid, the organic onium ions/ammonium ions 7a can be separated from the composite particles 5 and calculated by liquid chromatography, titration, IR measurement, or the like.
　複合粒子５の微細化セルロース１の表面側に結合した有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、複合粒子５に結合した微細化セルロース１の表面に存在するアニオン性官能基に対して０．０１当量以上であることが好ましく、より好ましくは０．０５当量以上であり、１．００当量以下であることが好ましく、より好ましくは０．５０当量以下、さらに好ましくは０．２５当量以下である。有機オニウムイオン／アンモニウムイオン７ａの平均結合量がこの範囲であると、微細化セルロース１の分散性、安定性が良好であるため、高収率に分散安定性の高い複合粒子５が得られる。有機オニウムイオン／アンモニウムイオン７ａの平均結合量（当量）は、複合粒子あたりの有機オニウムイオン／アンモニウムイオン７ａの平均結合量（ｍｍоｌ／ｇ）をＣ、複合粒子あたりのアニオン性官能基量（ｍｍоｌ／ｇ）をＤとすると、Ｃ／Ｄにて計算することができる。 The average binding amount of the organic onium ions/ammonium ions 7a bound to the surface side of the micronized cellulose 1 of the composite particles 5 is 0 with respect to the anionic functional groups present on the surface of the micronized cellulose 1 bonded to the composite particles 5. It is preferably 0.01 equivalent or more, more preferably 0.05 equivalent or more, and preferably 1.00 equivalent or less, more preferably 0.50 equivalent or less, and still more preferably 0.25 equivalent or less. be. When the average bonding amount of organic onium ions/ammonium ions 7a is within this range, the dispersibility and stability of the micronized cellulose 1 are good, so composite particles 5 with high dispersion stability can be obtained in a high yield. The average bonding amount (equivalent) of the organic onium ion/ammonium ion 7a is determined by C being the average bonding amount (mmol/g) of the organic onium ion/ammonium ion 7a per composite particle, and the amount of anionic functional groups per composite particle (mmol /g) is D, it can be calculated as C/D.
　本実施形態の微細化セルロース１は、有機オニウムイオン／アンモニウムイオン７ａが結合することによって、表面の一部が疎水化されている。そのため、特に限定されないが、微細化セルロース１を用いて作製した膜の水に対する接触角が４５°以上であることが好ましく、より好ましくは５０°以上である。接触角の測定方法は、微細化セルロース１の０．５％の水分散液を５ｃｍ×５ｃｍの容器に流し入れ、温度３０℃湿度８０％で乾燥させた後、更に窒素雰囲気下で乾燥させた膜に、接触角計（協和界面科学社製、ＰＣＡ－１）を用いて２μｌの純水を滴下して接触角を得ることができる。 Part of the surface of the micronized cellulose 1 of the present embodiment is hydrophobized by binding organic onium ions/ammonium ions 7a. Therefore, although not particularly limited, it is preferable that the contact angle to water of the film produced using the micronized cellulose 1 is 45° or more, and more preferably 50° or more. The contact angle was measured by pouring a 0.5% aqueous dispersion of micronized cellulose 1 into a 5 cm x 5 cm container, drying it at a temperature of 30°C and humidity of 80%, and then drying the film under a nitrogen atmosphere. The contact angle can be obtained by dropping 2 μl of pure water using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., PCA-1).
　微細化セルロース１のアニオン性官能基の対イオンとして、有機オニウムイオン／アンモニウムイオン７ａ以外のカチオン性物質が対イオンとして結合していても構わない。カチオン性物質としては、特に限定されないが、ナトリウムイオン、カリウムイオン、リチウムイオン等のアルカリ金属や、マグネシウムイオン、カルシウムイオン等のアルカリ土類金属等の金属イオンが挙げられる。微細化セルロース１の分散安定性の観点から、ナトリウムイオン、カリウムイオン、リチウムイオン等のアルカリ金属の金属イオンであることが好ましい。
　有機オニウムイオン／アンモニウムイオン７ａ以外のカチオン性物質の結合当量は、微細化セルロース１の分散安定性やエマルション安定性の観点から、微細化セルロース１あたり、好ましくは０．０２ｍｍｏｌ／ｇ以上であり、より好ましくは０．２ｍｍｏｌ／ｇ以上である。また、好ましくは３ｍｍｏｌ／ｇ以下であり、より好ましくは２．５ｍｍｏｌ／ｇ以下であり、更に好ましくは２ｍｍｏｌ／ｇ以下である。任意の２種以上のカチオン性物質が同時に微細化セルロース１に導入されていてもよい。カチオン性物質の平均結合量（ｍｍｏｌ／ｇ）は公知の方法で測定できる。例えば、金属イオンの場合、電子線マイクロアナライザーを用いたＥＰＭＡ（Electron Probe Micro Analyzer）法や、蛍光Ｘ線分析法、ＩＣＰ（Inductively Coupled Plasma）発光分光分析による元素分析等を簡易的な方法として例示できる。
　アニオン性官能基に結合するカチオン性物質の量は特に限定されないが、微細化セルロース１のアニオン性官能基に対して、０．９５当量以下、好ましくは０．９０以下、より好ましくは０．８０以下である。カチオン性物質の量が０．９５当量を超えるとエマルション安定が低くなるため、収率が下がり、粒子径分布が広くなることがある。カチオン性物質の平均結合量（当量）は、微細化セルロース１あたりのカチオン性物質の平均結合量（ｍｍоｌ／ｇ）をＥ、微細化セルロース１あたりのアニオン性官能基量（ｍｍоｌ／ｇ）をＢとすると、Ｅ／Ｂにて計算することができる。 As a counter ion for the anionic functional group of the micronized cellulose 1, a cationic substance other than the organic onium ion/ammonium ion 7a may be bound as a counter ion. Examples of cationic substances include, but are not limited to, alkali metals such as sodium ions, potassium ions and lithium ions, and metal ions such as alkaline earth metals such as magnesium ions and calcium ions. From the viewpoint of the dispersion stability of the micronized cellulose 1, alkali metal ions such as sodium ions, potassium ions, and lithium ions are preferred.
The binding equivalent of the cationic substance other than the organic onium ion/ammonium ion 7a is preferably 0.02 mmol/g or more per 1 micronized cellulose, from the viewpoint of the dispersion stability and emulsion stability of the micronized cellulose 1, More preferably, it is 0.2 mmol/g or more. Also, it is preferably 3 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2 mmol/g or less. Any two or more cationic substances may be introduced into the micronized cellulose 1 at the same time. The average binding amount (mmol/g) of the cationic substance can be measured by a known method. For example, in the case of metal ions, the EPMA (Electron Probe Micro Analyzer) method using an electron beam microanalyzer, X-ray fluorescence analysis, and ICP (Inductively Coupled Plasma) emission spectrometry are examples of simple methods for elemental analysis. can.
Although the amount of the cationic substance that binds to the anionic functional group is not particularly limited, it is 0.95 equivalent or less, preferably 0.90 or less, more preferably 0.80, relative to the anionic functional group of the micronized cellulose 1. It is below. If the amount of cationic substance exceeds 0.95 equivalents, the emulsion stability may be low, resulting in low yield and broad particle size distribution. The average binding amount (equivalent) of the cationic substance is defined by E as the average binding amount (mmol/g) of the cationic substance per 1 micronized cellulose, and the anionic functional group content (mmol/g) per 1 micronized cellulose. If B is used, the calculation can be performed by E/B.
　有機オニウムイオン／アンモニウムイオン７ａ以外のカチオン性物質の結合当量は、複合粒子５の分散安定性やエマルション安定性の観点から、複合粒子あたり、好ましくは０．０１μｍоｌ／ｇ以上であり、より好ましくは０．１μｍоｌ／ｇ以上である。また、好ましくは１００μｍоｌ／ｇ以下であり、より好ましくは５０μｍоｌ／ｇ以下であり、さらに好ましくは１０μｍоｌ／ｇ以下である。カチオン性物質の結合量がこの範囲であると複合粒子５の分散性が良好となる。任意の２種以上のカチオン性物質が同時に複合粒子５の表面の微細化セルロース１に導入されていてもよい。カチオン性物質の平均結合量（μｍоｌ／ｇ）は公知の方法で測定できる。例えば、金属イオンの場合、電子線マイクロアナライザーを用いたＥＰＭＡ法や、蛍光Ｘ線分析法、ＩＣＰ発光分光分析による元素分析等を簡易的な方法として例示できる。必要に応じて塩酸等の酸により複合粒子５を洗浄してカチオン性物質を分離してから元素分析等により分析してもよい。 From the viewpoint of the dispersion stability and emulsion stability of the composite particles 5, the binding equivalent of the cationic substance other than the organic onium ion/ammonium ion 7a is preferably 0.01 μmol/g or more per composite particle, more preferably It is 0.1 μmol/g or more. Also, it is preferably 100 μmol/g or less, more preferably 50 μmol/g or less, and even more preferably 10 μmol/g or less. When the binding amount of the cationic substance is within this range, the composite particles 5 have good dispersibility. Any two or more cationic substances may be introduced into the micronized cellulose 1 on the surface of the composite particles 5 at the same time. The average binding amount (μmol/g) of the cationic substance can be measured by a known method. For example, in the case of metal ions, an EPMA method using an electron beam microanalyzer, a fluorescent X-ray analysis method, an elemental analysis by ICP emission spectrometry, and the like can be exemplified as simple methods. If necessary, the composite particles 5 may be washed with an acid such as hydrochloric acid to separate the cationic substance and then analyzed by elemental analysis or the like.
　複合粒子５の微細化セルロース１の表面側に結合したカチオン性物質の平均結合量は、複合粒子５に結合した微細化セルロース１の表面に存在するアニオン性官能基に対して０．０１当量以上であることが好ましく、より好ましくは０．０５当量以上であり、好ましくは１．００当量以下であることが好ましく、より好ましくは０．５０当量以下、更により好ましくは０．２５当量以下である。カチオン性物質の平均結合量がこの範囲であると、微細化セルロース１の安定性が良好で、エマルション安定もよく、高収率にて複合粒子５を得ることができ、得られた複合粒子５の分散性も良好となる。カチオン性物質の平均結合量（当量）は、複合粒子あたりのカチオン性物質の平均結合量（ｍｍоｌ／ｇ）をＦ、複合粒子あたりのアニオン性官能基量（ｍｍоｌ／ｇ）をＤとすると、Ｆ／Ｄにて計算することができる。 The average binding amount of the cationic substance bound to the surface side of the micronized cellulose 1 of the composite particles 5 is 0.01 equivalent or more with respect to the anionic functional groups present on the surface of the micronized cellulose 1 bonded to the composite particles 5. is preferably 0.05 equivalents or more, preferably 1.00 equivalents or less, more preferably 0.50 equivalents or less, and even more preferably 0.25 equivalents or less. . When the average binding amount of the cationic substance is within this range, the stability of the micronized cellulose 1 is good, the emulsion stability is good, and the composite particles 5 can be obtained in a high yield. The dispersibility of is also improved. The average binding amount (equivalent) of the cationic substance is given by the average binding amount (mmol/g) of the cationic substance per composite particle, F, and the anionic functional group amount (mmol/g) per composite particle, D. It can be calculated in F/D.
　また、コア粒子３は、少なくとも一種類以上のポリマーを含むことが好ましい。ポリマーは、公知のポリマーを用いることができ、重合性モノマーを公知の方法で重合させたポリマーでもよい。 Also, the core particles 3 preferably contain at least one type of polymer. A known polymer can be used as the polymer, and a polymer obtained by polymerizing a polymerizable monomer by a known method may be used.
　ポリマーとしては、例えば、アクリル系ポリマー、エポキシ系ポリマー、ポリエステル系ポリマー、アミノ系ポリマー、シリコーン系ポリマー、フッ素系ポリマー、ウレタン・イソシアネート系ポリマー等が挙げられる。 Examples of polymers include acrylic polymers, epoxy polymers, polyester polymers, amino polymers, silicone polymers, fluorine polymers, and urethane/isocyanate polymers.
　近年、環境への配慮から、使用後に自然界の微生物によって分解され、最終的には水と二酸化炭素になることができる生分解性を有する粉体が強く望まれている。生分解性ポリマーを本実施形態のコア粒子３に用いることができる。
　特に限定されないが、ポリマーは生分解性ポリマーであることが好ましい。生分解性とは、土壌や海水中などの地球環境において分解して消滅するポリマー、または／および生体内で分解して消滅するポリマーのことである。一般的に、土壌や海水中では微生物がもつ酵素によりポリマーが分解されるのに対し、生体内では酵素を必要とせず物理化学的な加水分解により分解される。ポリマーの分解は、ポリマーが低分子化或いは水溶性化して形態を消失することである。ポリマーの分解は、特に限定されないが、主鎖、側鎖、架橋点の加水分解や、主鎖の酸化分解により起こる。 In recent years, due to environmental considerations, there has been a strong demand for biodegradable powders that can be decomposed by microorganisms in nature after use and finally become water and carbon dioxide. A biodegradable polymer can be used for the core particle 3 of this embodiment.
Although not particularly limited, the polymer is preferably a biodegradable polymer. Biodegradability refers to a polymer that decomposes and disappears in the global environment such as soil and seawater, and/or a polymer that decomposes and disappears in vivo. In general, polymers are degraded by enzymes possessed by microorganisms in soil or seawater, whereas in vivo they are degraded by physicochemical hydrolysis without the need for enzymes. Degradation of a polymer means that the polymer becomes low-molecular-weight or water-soluble and loses its shape. Decomposition of the polymer is not particularly limited, but occurs by hydrolysis of the main chain, side chains and cross-linking points, and oxidative decomposition of the main chain.
　生分解性ポリマーには、天然由来の天然高分子、或いは合成高分子がある。 Biodegradable polymers include natural polymers derived from nature and synthetic polymers.
　天然高分子としては、例えば、植物が生産する多糖（セルロース、デンプン、アルギン酸等）、動物が生産する多糖（キチン、キトサン、ヒアルロン酸等）、タンパク質（コラーゲン、ゼラチン、アルブミン等）、微生物が生産するポリエステル（ポリ（３－ヒドロキシアルカノエート））、多糖（ヒアルロン酸等）等が挙げられる。 Examples of natural polymers include polysaccharides produced by plants (cellulose, starch, alginic acid, etc.), polysaccharides produced by animals (chitin, chitosan, hyaluronic acid, etc.), proteins (collagen, gelatin, albumin, etc.), and those produced by microorganisms. polyester (poly(3-hydroxyalkanoate)), polysaccharide (hyaluronic acid, etc.) and the like.
　合成高分子としては、例えば、脂肪族ポリエステル、ポリオール、ポリカーボネート等が挙げられる。 Synthetic polymers include, for example, aliphatic polyesters, polyols, and polycarbonates.
　脂肪酸ポリエステルとしては、例えば、グリコール・ジカルボン酸重縮合系（ポリエチレンサクシネート、ポリブチレンサクシネート等）、ポリラクチド類（ポリグリコール酸、ポリ乳酸等）、ポリラクトン類（β－カプロラクトン、ε－カプロラクトン等）、その他（ポリブチレンテレフタレート・アジペート等）が挙げられる。 Fatty acid polyesters include, for example, glycol-dicarboxylic acid polycondensation systems (polyethylene succinate, polybutylene succinate, etc.), polylactides (polyglycolic acid, polylactic acid, etc.), polylactones (β-caprolactone, ε-caprolactone, etc.). , and others (polybutylene terephthalate, adipate, etc.).
　ポリオールとしては、例えば、ポリビニルアルコール等が挙げられる。 Examples of polyols include polyvinyl alcohol.
　ポリカーボネートとしては、例えば、ポリエステルカーボネート等が挙げられる。 Examples of polycarbonate include polyester carbonate.
　その他、ポリ酸無水物、ポリシアノアクリレート、ポリオルソエステル、ポリフォスファゼン等も生分解性の合成高分子である。 In addition, polyacid anhydrides, polycyanoacrylates, polyorthoesters, polyphosphazenes, etc. are also biodegradable synthetic polymers.
　コア粒子３はポリマー以外に他の成分を含んでも良い。例えば、着色剤、吸油剤、光遮蔽剤（紫外線吸収剤、紫外線散乱剤等）、抗菌剤、酸化防止剤、制汗剤、消泡剤、帯電防止剤、結合剤、漂白剤、キレート剤、脱臭成分、芳香剤、香料、ふけ防止活性物質、皮膚軟化剤、防虫剤、防腐剤、天然抽出物、美容成分、ｐＨ調整剤、ビタミン、アミノ酸、ホルモン、油脂やロウ類をはじめとする油性原料、界面活性剤、無機質粒子（酸化チタン、シリカ、クレー等）、等が挙げられる。これらの他成分は固体、気体、液体のいずれの形態であってもよい。他成分の複合粒子５中の含有率は、特に限定されず、複合粒子５が安定して形態を保つことができる範囲であることが好ましい。他成分の含有率は、複合粒子５を１００質量部とすると、他成分は０．００１質量部以上８０質量部以下であることが好ましい。 The core particles 3 may contain other components in addition to the polymer. For example, colorants, oil absorbers, light shielding agents (ultraviolet absorbers, ultraviolet scattering agents, etc.), antibacterial agents, antioxidants, antiperspirants, antifoaming agents, antistatic agents, binders, bleaching agents, chelating agents, Deodorizing ingredients, fragrances, fragrances, anti-dandruff actives, emollients, insect repellents, preservatives, natural extracts, beauty ingredients, pH adjusters, vitamins, amino acids, hormones, oils and waxes and other oil-based ingredients , surfactants, inorganic particles (titanium oxide, silica, clay, etc.), and the like. These other components may be in solid, gaseous or liquid form. The content of other components in the composite particles 5 is not particularly limited, and is preferably within a range in which the composite particles 5 can stably maintain their shape. The content of other components is preferably 0.001 parts by mass or more and 80 parts by mass or less when the composite particles 5 are 100 parts by mass.
＜複合粒子５の製造方法＞
　本実施形態の複合粒子５の製造方法の詳細について、図２を参照しつつ説明する。本実施形態に係る複合粒子の製造方法は、セルロース原料を分散溶媒４中で解繊して、微細化セルロース１が分散された微細化セルロース分散液を得る第一工程と、微細化セルロース分散液に有機オニウム化合物／アミンを添加して、微細化セルロース１に有機オニウムカチオン／アンモニウムイオン７ａを結合させる第二工程と、微細化セルロース分散液中においてコア粒子前駆体２を含む液滴６をエマルションとして安定化させる第三工程と、コア粒子前駆体２を固体化させてコア粒子３とし、コア粒子３と不可分に結合した微細化セルロース１がコア粒子３を被覆した複合粒子５を得る第四工程と、を備える。 <Method for producing composite particles 5>
Details of the method for producing the composite particles 5 of the present embodiment will be described with reference to FIG. The method for producing composite particles according to the present embodiment includes a first step of defibrating a cellulose raw material in a dispersion solvent 4 to obtain a micronized cellulose dispersion in which micronized cellulose 1 is dispersed, and a micronized cellulose dispersion. A second step of adding an organic onium compound/amine to the micronized cellulose 1 to bind the organic onium cation/ammonium ion 7a to the micronized cellulose dispersion liquid, and emulsifying the droplets 6 containing the core particle precursor 2 in the micronized cellulose dispersion liquid. and a fourth step of solidifying the core particle precursor 2 to form a core particle 3 to obtain a composite particle 5 in which the core particle 3 is coated with the micronized cellulose 1 inseparably bound to the core particle 3. and a step.
　上記製造方法により得られた複合粒子５は分散体として得られる。分散体から分散溶媒４を除去すると、取り扱い性の良い複合粒子５の乾燥固形物が得られる。分散溶媒４の除去方法は特に限定されず、例えば遠心分離法やろ過法によって分散溶媒４を除去する方法や、オーブン等で分散溶媒４を気化させて除去する方法を例示できる。例えば、図２に示すように精製乾燥することで複合粒子５の乾燥固形物を得てもよい。
　この際、得られる複合粒子５の乾燥固形物は膜状や凝集体状にはならず、きめ細やかな粉体である。この理由は定かではないが、複合粒子５を含む分散液の場合、微細化セルロース１が表面に固定化された略真球状の複合粒子５であるため、分散溶媒４を除去しても微細化セルロース１同士が凝集することなく、隣り合う複合粒子間で点接触するのみであることが一因と考えられる。複合粒子５は凝集を生じないため、乾燥粉体として得られた複合粒子５を溶媒に再分散することも容易であり、再分散後も表面に結合された微細化セルロース１に由来した分散安定性を示す。 The composite particles 5 obtained by the above production method are obtained as a dispersion. When the dispersion solvent 4 is removed from the dispersion, a dry solid of composite particles 5 with good handleability is obtained. The method of removing the dispersion solvent 4 is not particularly limited, and examples thereof include a method of removing the dispersion solvent 4 by a centrifugal separation method or a filtration method, and a method of removing the dispersion solvent 4 by evaporating it in an oven or the like. For example, as shown in FIG. 2, a dry solid of composite particles 5 may be obtained by purification and drying.
At this time, the dry solid matter of the composite particles 5 obtained does not form a film or an aggregate, but is a fine powder. Although the reason for this is not clear, in the case of the dispersion containing the composite particles 5, since the composite particles 5 are substantially spherical composite particles 5 in which the micronized cellulose 1 is immobilized on the surface, even if the dispersion solvent 4 is removed, the micronized One of the reasons for this is considered to be that the cellulose 1 does not agglomerate and the adjacent composite particles are only in point contact with each other. Since the composite particles 5 do not aggregate, it is easy to redisperse the composite particles 5 obtained as a dry powder in a solvent. show gender.
　複合粒子５の乾燥粉体は溶媒をほとんど含まず、さらに溶媒に再分散可能であることを特長とする乾燥固形物であり、具体的には固形分率を８０％以上とすることができ、さらに９０％以上とすることができ、さらに９５％以上とすることができる。
　複合粒子５の分散体は、溶媒をほぼ除去することが容易であるため、輸送費の削減、腐敗防止、添加率向上、樹脂との混練効率向上、といった観点から好ましい効果を得る。なお、乾燥処理により固形分率を８０％以上にした場合でも、微細化セルロース１は吸湿しやすいため、空気中の水分を吸着して固形分率が経時的に低下し、保管中に８０％以下となる可能性がある。しかしながら、複合粒子５は乾燥粉体として容易に得られ、さらに再分散させ得ることが特長である本発明の技術思想を考慮すると、複合粒子５を含む乾燥粉体の固形分率を８０％以上とする工程を経て得られた乾燥固形物であれば、本発明の技術的範囲に含まれると言うべきである。
　以下、製造方法の各工程について詳細に説明する。 The dry powder of the composite particles 5 is a dry solid that contains almost no solvent and is redispersible in a solvent. Specifically, the solid content can be 80% or more, Further, it can be 90% or more, and further can be 95% or more.
Since the dispersion of the composite particles 5 can be almost easily removed from the solvent, favorable effects can be obtained from the viewpoints of reduction in transportation costs, prevention of spoilage, improvement in addition rate, and improvement in kneading efficiency with the resin. Even when the solid content is increased to 80% or more by drying, the micronized cellulose 1 easily absorbs moisture. The following may occur. However, considering the technical idea of the present invention, which is characterized in that the composite particles 5 can be easily obtained as a dry powder and can be redispersed, the solid content of the dry powder containing the composite particles 5 should be 80% or more. It should be said that any dry solid obtained through the process of is included in the technical scope of the present invention.
Each step of the manufacturing method will be described in detail below.
（第一工程）
　第一工程はセルロース原料を分散溶媒４中で解繊して微細化セルロース分散液を得る工程である。まず、各種セルロース原料を分散溶媒４中に分散し、懸濁液とする。懸濁液中のセルロース原料の濃度としては０．１％以上１０％未満が好ましい。懸濁液中のセルロース原料の濃度が０．１％未満であると、溶媒過多となり生産性を損なう傾向があるため好ましくない。また、懸濁液中のセルロース原料の濃度が１０％以上になると、セルロース原料の解繊に伴い懸濁液が急激に増粘し、均一な解繊処理が困難となる傾向があるため好ましくない。懸濁液作製に用いる分散溶媒４としては、水を５０％以上含むことが好ましい。懸濁液中の水の割合が５０％未満になると、後述するセルロース原料を分散溶媒４中で解繊して微細化セルロース分散液を得る工程において、微細化セルロース１の分散が阻害される傾向がある。 (First step)
The first step is a step of defibrating the cellulose raw material in the dispersion solvent 4 to obtain a fine cellulose dispersion. First, various cellulose raw materials are dispersed in the dispersion solvent 4 to form a suspension. The concentration of the cellulose raw material in the suspension is preferably 0.1% or more and less than 10%. If the concentration of the cellulose raw material in the suspension is less than 0.1%, the amount of solvent becomes excessive, which tends to impair productivity, which is not preferable. Further, if the concentration of the cellulose raw material in the suspension is 10% or more, the suspension will rapidly increase in viscosity as the cellulose raw material is defibrated, and uniform defibration tends to become difficult, which is not preferable. . The dispersion solvent 4 used for preparing the suspension preferably contains 50% or more water. If the proportion of water in the suspension is less than 50%, the dispersion of the micronized cellulose 1 tends to be inhibited in the process of obtaining a micronized cellulose dispersion by fibrillating the cellulose raw material in the dispersion solvent 4, which will be described later. There is
　水以外に含まれる溶媒としては親水性溶媒が好ましい。親水性溶媒については特に制限はないが、例えば、メタノール、エタノール、イソプロパノールなどのアルコール類や、テトラヒドロフラン等の環状エーテル類が好ましい。必要に応じて、セルロースや生成する微細化セルロース１の分散性を上げるために、例えば、懸濁液のｐＨ調整を行ってもよい。ｐＨ調整に用いられるアルカリ水溶液としては、例えば、水酸化ナトリウム水溶液、水酸化リチウム水溶液、水酸化カリウム水溶液、アンモニア水溶液、水酸化テトラメチルアンモニウム（テトラメチルアンモニウムヒドロキシド、ＴＭＡＨ）水溶液、水酸化テトラエチルアンモニウム（テトラエチルアンモニウムヒドロキシド、ＴＥＡＨ）水溶液、水酸化テトラブチルアンモニウム（テトラブチルアンモニウムヒドロキシド、ＴＢＡＨ）水溶液、水酸化ベンジルトリメチルアンモニウム水溶液などの有機オニウム化合物などが挙げられる。コストなどの面から水酸化ナトリウム水溶液が好ましい。 A hydrophilic solvent is preferable as the solvent contained in addition to water. The hydrophilic solvent is not particularly limited, but alcohols such as methanol, ethanol and isopropanol, and cyclic ethers such as tetrahydrofuran are preferred. If necessary, the pH of the suspension may be adjusted, for example, in order to increase the dispersibility of the cellulose and the micronized cellulose 1 to be produced. Examples of alkaline aqueous solutions used for pH adjustment include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide (tetramethylammonium hydroxide, TMAH) aqueous solution, and tetraethylammonium hydroxide. organic onium compounds such as (tetraethylammonium hydroxide, TEAH) aqueous solution, tetrabutylammonium hydroxide (tetrabutylammonium hydroxide, TBAH) aqueous solution, and benzyltrimethylammonium hydroxide aqueous solution; A sodium hydroxide aqueous solution is preferable from the viewpoint of cost.
　続いて、懸濁液に物理的解繊処理を施して、セルロース原料を微細化する。物理的解繊処理の方法としては特に限定されないが、例えば、高圧ホモジナイザー、超高圧ホモジナイザー、ボールミル、ロールミル、カッターミル、遊星ミル、ジェットミル、アトライター、グラインダー、ジューサーミキサー、ホモミキサー、超音波ホモジナイザー、ナノジナイザー、水中対向衝突などの機械的処理が挙げられる。このような物理的解繊処理を行うことで、懸濁液中のセルロースが微細化され、その構造の少なくとも一辺がナノメートルオーダーになるまで微細化されたセルロース（微細化セルロース１）の分散液を得ることができる。また、このときの物理的解繊処理の時間や回数により、得られる微細化セルロース１の数平均短軸径及び数平均長軸径を調整することができる。 Subsequently, the suspension is subjected to a physical defibration process to refine the cellulose raw material. The method of physical fibrillation treatment is not particularly limited, but for example, high pressure homogenizer, ultra high pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer. , nanogenizer, and mechanical treatments such as underwater counter-collision. By performing such a physical fibrillation treatment, the cellulose in the suspension is made finer, and at least one side of the structure is made finer to the order of nanometers (micronized cellulose 1) dispersion liquid. can be obtained. Moreover, the number average minor axis diameter and the number average major axis diameter of the micronized cellulose 1 to be obtained can be adjusted by the time and frequency of the physical defibration treatment at this time.
　上記のようにして、その構造の少なくとも一辺がナノメートルオーダーになるまで微細化された微細化セルロース１の分散体（微細化セルロース分散液）が得られる。得られた分散体は、そのまま、又は希釈、濃縮等を行って、後述するＯ／Ｗ型エマルションの安定化剤として用いることができる。
　また、微細化セルロース１の分散体は、必要に応じて、本発明の効果を損なわない範囲で、セルロース及びｐＨ調整に用いた成分以外の他の成分を含有してもよい。上記他の成分としては、特に限定されず、複合粒子５の用途等に応じて、公知の添加剤から適宜選択できる。具体的には、アルコキシシラン等の有機金属化合物又はその加水分解物、無機層状化合物、無機針状鉱物、消泡剤、無機系粒子、有機系粒子、潤滑剤、酸化防止剤、帯電防止剤、紫外線吸収剤、安定化剤、磁性粉、配向促進剤、可塑剤、架橋剤、磁性体、医薬品、農薬、香料、接着剤、酵素、顔料、染料、消臭剤、金属、金属酸化物、無機酸化物等が挙げられる。 As described above, a dispersion (micronized cellulose dispersion) of the micronized cellulose 1, which is micronized so that at least one side of the structure is on the order of nanometers, is obtained. The resulting dispersion can be used as it is or after dilution, concentration, etc., as a stabilizer for an O/W emulsion, which will be described later.
Further, the dispersion of the micronized cellulose 1 may optionally contain other components other than the cellulose and the components used for adjusting the pH within a range that does not impair the effects of the present invention. The other components are not particularly limited, and can be appropriately selected from known additives according to the use of the composite particles 5 and the like. Specifically, organometallic compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic acicular minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, Ultraviolet absorbers, stabilizers, magnetic powders, orientation promoters, plasticizers, cross-linking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxides and the like.
　通常、微細化セルロース１は、ミクロフィブリル構造由来の繊維形状であるため、本実施形態の製造方法に用いる微細化セルロース１としては、以下に示す範囲にある繊維形状のものが好ましい。すなわち、微細化セルロース１の形状としては、繊維状であることが好ましい。また、繊維状の微細化セルロース１は、短軸径において数平均短軸径が１ｎｍ以上１０００ｎｍ以下であればよく、好ましくは２ｎｍ以上５００ｎｍ以下であればよい。ここで、数平均短軸径が１ｎｍ未満では高結晶性の剛直な微細化セルロース１繊維構造をとることができず、エマルションの安定化と、エマルションを鋳型とした重合反応やポリマーの固体化等による複合粒子５の形成が難しくなる傾向がある。一方、短軸径において数平均短軸径が１０００ｎｍを超えると、エマルションを安定化させるにはサイズが大きくなり過ぎるため、得られる複合粒子５のサイズや形状を制御することが困難となる傾向がある。また、数平均長軸径においては特に制限はないが、好ましくは数平均短軸径の５倍以上であればよい。数平均長軸径が数平均短軸径の５倍未満であると、複合粒子５のサイズや形状を十分に制御することが困難となる傾向があるために好ましくない。 Because the micronized cellulose 1 usually has a fiber shape derived from a microfibril structure, the micronized cellulose 1 used in the production method of the present embodiment preferably has a fiber shape within the range shown below. That is, the shape of the micronized cellulose 1 is preferably fibrous. The number average minor axis diameter of the fibrous micronized cellulose 1 should be 1 nm or more and 1000 nm or less, preferably 2 nm or more and 500 nm or less. Here, if the number average minor axis diameter is less than 1 nm, a highly crystalline rigid micronized cellulose 1-fiber structure cannot be obtained, and the emulsion is stabilized, the polymerization reaction is performed using the emulsion as a template, and the polymer is solidified. It tends to be difficult to form the composite particles 5 by On the other hand, if the number average minor axis diameter exceeds 1000 nm, the size becomes too large to stabilize the emulsion, and it tends to be difficult to control the size and shape of the obtained composite particles 5. be. The number average major axis diameter is not particularly limited, but it is preferably five times or more the number average minor axis diameter. If the number average major axis diameter is less than five times the number average minor axis diameter, it tends to be difficult to sufficiently control the size and shape of the composite particles 5, which is not preferable.
　なお、微細化セルロース１の数平均短軸径は、例えば、透過型電子顕微鏡観察又は原子間力顕微鏡観察により１００本の繊維の短軸径（最小径）を測定し、その平均値として求められる。一方、微細化セルロース１の数平均長軸径は、例えば、透過型電子顕微鏡観察又は原子間力顕微鏡観察により１００本の繊維の長軸径（最大径）を測定し、その平均値として求められる。 The number average minor axis diameter of the micronized cellulose 1 is obtained by measuring the minor axis diameter (minimum diameter) of 100 fibers by, for example, transmission electron microscope observation or atomic force microscope observation, and calculating the average value thereof. . On the other hand, the number average major axis diameter of the micronized cellulose 1 is obtained by measuring the major axis diameter (maximum diameter) of 100 fibers by, for example, transmission electron microscopy or atomic force microscopy, and calculating the average value. .
　微細化セルロース１の原料として用いることができるセルロースの種類や結晶構造も特に限定されない。具体的には、セルロースＩ型結晶からなる原料としては、例えば、木材系天然セルロースに加えて、コットンリンター、竹、麻、バガス、ケナフ、バクテリアセルロース、ホヤセルロース、バロニアセルロースといった非木材系天然セルロースを用いることができる。さらには、セルロースＩＩ型結晶からなるレーヨン繊維、キュプラ繊維に代表される再生セルロースも用いることができる。材料調達の容易さから、木材系天然セルロースを原料とすることが好ましい。木材系天然セルロースとしては、特に限定されず、例えば、針葉樹パルプや広葉樹パルプ、古紙パルプ、など、一般的にセルロースナノファイバーの製造に用いられるものを用いることができる。精製及び微細化のしやすさから、針葉樹パルプが好ましい。 The type and crystal structure of cellulose that can be used as a raw material for micronized cellulose 1 are not particularly limited. Specifically, raw materials composed of type I cellulose crystals include, in addition to natural wood cellulose, non-wood natural cellulose such as cotton linter, bamboo, hemp, bagasse, kenaf, bacterial cellulose, sea squirt cellulose, and valonia cellulose. can be used. Furthermore, regenerated cellulose represented by rayon fibers and cupra fibers composed of cellulose type II crystals can also be used. It is preferable to use wood-based natural cellulose as a raw material because of the ease of material procurement. The wood-based natural cellulose is not particularly limited. For example, softwood pulp, hardwood pulp, waste paper pulp, and the like, which are generally used for producing cellulose nanofibers, can be used. Softwood pulp is preferred because of its ease of refining and miniaturization.
　さらに微細化セルロース原料は化学改質されていることが好ましい。より具体的には、微細化セルロース原料の結晶表面にアニオン性官能基が導入されていることが好ましい。セルロース結晶表面にアニオン性官能基が導入されていることによって浸透圧効果でセルロース結晶間に溶媒が浸入しやすくなり、セルロース原料の微細化が進行しやすくなるためである。
　セルロースの結晶表面に導入されるアニオン性官能基の種類や導入方法は特に限定されず、カルボキシ基、リン酸基、スルホ基等が挙げられる、カルボキシ基やリン酸基が好ましい。セルロース結晶表面への選択的な導入のしやすさから、カルボキシ基が好ましい。 Furthermore, it is preferable that the micronized cellulose raw material is chemically modified. More specifically, it is preferable that an anionic functional group is introduced to the crystal surface of the micronized cellulose raw material. This is because the presence of an anionic functional group on the surface of the cellulose crystals facilitates penetration of the solvent into the space between the cellulose crystals due to the effect of osmotic pressure, thereby facilitating the miniaturization of the cellulose raw material.
The type and introduction method of the anionic functional group to be introduced into the crystal surface of cellulose are not particularly limited, and a carboxy group and a phosphate group, such as a carboxy group, a phosphate group, and a sulfo group, are preferred. A carboxy group is preferred because of its ease of selective introduction to the cellulose crystal surface.
　セルロースの繊維表面にカルボキシ基を導入する方法は、特に限定されない。具体的には、例えば、高濃度アルカリ水溶液中でセルロースをモノクロロ酢酸又はモノクロロ酢酸ナトリウムと反応させることによりカルボキシメチル化を行ってもよい。また、オートクレーブ中でガス化したマレイン酸やフタル酸等の無水カルボン酸系化合物とセルロースを直接反応させてカルボキシ基を導入してもよい。さらには、水系の比較的温和な条件で、可能な限り構造を保ちながら、アルコール性一級炭素の酸化に対する選択性が高い、ＴＥＭＰＯをはじめとするＮ－オキシル化合物の存在下で、共酸化剤を用いた手法を用いてもよい。カルボキシ基導入部位の選択性及び環境負荷低減のためにはＮ－オキシル化合物を用いた酸化がより好ましい。 The method of introducing carboxyl groups onto the surface of cellulose fibers is not particularly limited. Specifically, for example, carboxymethylation may be performed by reacting cellulose with monochloroacetic acid or sodium monochloroacetate in a high-concentration alkaline aqueous solution. Alternatively, a carboxyl group may be introduced by directly reacting a carboxylic acid anhydride compound such as maleic acid or phthalic acid gasified in an autoclave with cellulose. Furthermore, under relatively mild conditions of an aqueous system, a co-oxidant is added in the presence of an N-oxyl compound such as TEMPO, which has a high selectivity for the oxidation of alcoholic primary carbon while maintaining the structure as much as possible. You may use the method used. Oxidation using an N-oxyl compound is more preferable for the selectivity of the carboxy group-introducing site and the reduction of the environmental load.
　ここで、Ｎ－オキシル化合物としては、例えば、ＴＥＭＰＯ（２，２，６，６－テトラメチルピペリジニル－１－オキシラジカル）、２，２，６，６－テトラメチル－４－ヒドロキシピペリジン－１－オキシル、４－メトキシ－２，２，６，６－テトラメチルピペリジン－Ｎ－オキシル、４－エトキシ－２，２，６，６－テトラメチルピペリジン－Ｎ－オキシル、４－アセトアミド－２，２，６，６－テトラメチルピペリジン－Ｎ－オキシル、等が挙げられる。そのなかでも、反応性が高いＴＥＭＰＯが好ましい。Ｎ－オキシル化合物の使用量は、触媒としての量でよく、特に限定されない。通常、酸化処理する木材系天然セルロースの固形分に対して０．０１～５．０質量％程度である。 Here, examples of the N-oxyl compound include TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy radical), 2,2,6,6-tetramethyl-4-hydroxypiperidine- 1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2, 2,6,6-tetramethylpiperidine-N-oxyl, and the like. Among them, TEMPO, which has high reactivity, is preferable. The amount of the N-oxyl compound to be used is not particularly limited and may be the amount required for the catalyst. Usually, it is about 0.01 to 5.0% by mass based on the solid content of wood-based natural cellulose to be oxidized.
　Ｎ－オキシル化合物を用いた酸化方法としては、例えば木材系天然セルロースを水中に分散させ、Ｎ－オキシル化合物の共存下で酸化処理する方法が挙げられる。このとき、Ｎ－オキシル化合物とともに、共酸化剤を併用することが好ましい。この場合、反応系内において、Ｎ－オキシル化合物が順次共酸化剤により酸化されてオキソアンモニウム塩が生成し、上記オキソアンモニウム塩によりセルロースが酸化される。この酸化処理によれば、温和な条件でも酸化反応が円滑に進行し、カルボキシ基の導入効率が向上する。酸化処理を温和な条件で行うと、セルロースの結晶構造を維持しやすい。 As an oxidation method using an N-oxyl compound, for example, wood-based natural cellulose is dispersed in water, and an oxidation treatment is performed in the presence of an N-oxyl compound. At this time, it is preferable to use a co-oxidizing agent together with the N-oxyl compound. In this case, the N-oxyl compound is sequentially oxidized by the co-oxidizing agent in the reaction system to form an oxoammonium salt, and the oxoammonium salt oxidizes the cellulose. According to this oxidation treatment, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group is improved. If the oxidation treatment is performed under mild conditions, the crystalline structure of cellulose can be easily maintained.
　共酸化剤としては、例えば、ハロゲン、次亜ハロゲン酸、亜ハロゲン酸や過ハロゲン酸、又はそれらの塩、ハロゲン酸化物、窒素酸化物、過酸化物など、酸化反応を推進することが可能であれば、いずれの酸化剤も用いることができる。入手の容易さや反応性から、次亜塩素酸ナトリウムが好ましい。上記共酸化剤の使用量は、酸化反応を促進することができる量でよく、特に限定されない。通常、酸化処理する木材系天然セルロースの固形分に対して１～２００質量％程度である。
　また、Ｎ－オキシル化合物及び共酸化剤とともに、臭化物及びヨウ化物からなる群から選ばれる少なくとも１種の化合物をさらに併用してもよい。これにより、酸化反応を円滑に進行させることができ、カルボキシ基の導入効率を改善することができる。このような化合物としては、臭化ナトリウム又は臭化リチウムが好ましく、コストや安定性から、臭化ナトリウムがより好ましい。化合物の使用量は、酸化反応を促進することができる量でよく、特に限定されない。通常、酸化処理する木材系天然セルロースの固形分に対して１～５０質量％程度である。 Examples of co-oxidants include halogens, hypohalous acids, halogenous acids and perhalogenates, salts thereof, halogen oxides, nitrogen oxides, peroxides, etc., which can promote the oxidation reaction. Any oxidizing agent, if any, can be used. Sodium hypochlorite is preferred because of its availability and reactivity. The amount of the co-oxidizing agent to be used is not particularly limited and may be an amount capable of promoting the oxidation reaction. Usually, it is about 1 to 200% by mass based on the solid content of the wood-based natural cellulose to be oxidized.
At least one compound selected from the group consisting of bromides and iodides may be used in combination with the N-oxyl compound and the co-oxidizing agent. As a result, the oxidation reaction can proceed smoothly, and the introduction efficiency of the carboxy group can be improved. As such a compound, sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable in terms of cost and stability. The amount of the compound to be used is not particularly limited as long as it can promote the oxidation reaction. Usually, it is about 1 to 50% by mass based on the solid content of the wood-based natural cellulose to be oxidized.
　酸化反応の反応温度は、４℃以上８０℃以下が好ましく、１０℃以上７０℃以下がより好ましい。酸化反応の反応温度が４℃未満であると、試薬の反応性が低下し反応時間が長くなってしまう傾向がある。酸化反応の反応温度が８０℃を超えると副反応が促進して試料であるセルロースが低分子化して高結晶性の剛直な微細化セルロース１繊維構造が崩壊し、Ｏ／Ｗ型エマルションの安定化剤として用いることが困難となる傾向がある。
　また、酸化処理の反応時間は、反応温度、所望のカルボキシ基量等を考慮して適宜設定でき、特に限定されないが、通常、１０分～５時間程度である。 The reaction temperature of the oxidation reaction is preferably 4° C. or higher and 80° C. or lower, more preferably 10° C. or higher and 70° C. or lower. When the reaction temperature of the oxidation reaction is lower than 4°C, the reactivity of the reagent tends to decrease and the reaction time tends to become longer. When the reaction temperature of the oxidation reaction exceeds 80°C, the side reaction is accelerated, the cellulose sample becomes low-molecular, and the highly crystalline, rigid, micronized cellulose 1-fiber structure collapses, stabilizing the O/W emulsion. It tends to be difficult to use as an agent.
Moreover, the reaction time of the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy groups, etc., and is not particularly limited, but is usually about 10 minutes to 5 hours.
　酸化反応時の反応系のｐＨは特に限定されないが、９～１１が好ましい。ｐＨが９以上であると反応を効率良く進めることができる。ｐＨが１１を超えると副反応が進行し、試料であるセルロースの分解が促進されてしまう可能性がある。また、酸化処理においては、酸化が進行するにつれて、カルボキシ基が生成することにより系内のｐＨが低下してしまうため、酸化処理中、反応系のｐＨを９～１１に保つことが好ましい。反応系のｐＨを９～１１に保つ方法としては、例えば、ｐＨの低下に応じてアルカリ水溶液を添加する方法が挙げられる。 Although the pH of the reaction system during the oxidation reaction is not particularly limited, it is preferably 9-11. When the pH is 9 or more, the reaction can proceed efficiently. If the pH exceeds 11, side reactions may proceed and the decomposition of the sample cellulose may be accelerated. In addition, in the oxidation treatment, as the oxidation progresses, carboxyl groups are generated and the pH in the system decreases, so it is preferable to maintain the pH of the reaction system at 9 to 11 during the oxidation treatment. As a method of maintaining the pH of the reaction system at 9 to 11, for example, a method of adding an alkaline aqueous solution according to the decrease in pH can be mentioned.
　アルカリ水溶液としては、例えば、水酸化ナトリウム水溶液、水酸化リチウム水溶液、水酸化カリウム水溶液、アンモニア水溶液、水酸化テトラメチルアンモニウム（テトラメチルアンモニウムヒドロキシド、ＴＭＡＨ）水溶液、水酸化テトラエチルアンモニウム（テトラエチルアンモニウムヒドロキシド、ＴＥＡＨ）水溶液、水酸化テトラブチルアンモニウム（テトラブチルアンモニウムヒドロキシド、ＴＢＡＨ）水溶液、水酸化ベンジルトリメチルアンモニウム水溶液などの有機オニウム化合物などが挙げられる。コストなどの面から水酸化ナトリウム水溶液、水酸化リチウム水溶液、水酸化カリウム水溶液が好ましい。
　酸化反応時のｐＨを保つのに用いるアルカリ水溶液に含まれるカチオン性物質が、酸化反応により生成したカルボキシ基の対イオンとして結合する。ＴＥＭＰＯ酸化セルロースのカルボキシ基の対イオンのカチオン性物質は、ナトリウムイオン、カリウムイオン、リチウムイオン等のアルカリ金属や、マグネシウムイオンやカルシウムイオン等のアルカリ土類金属等の金属イオンとなることが好ましい。ＴＥＭＰＯ酸化セルロースのカルボキシ基の対イオンのカチオン性物質が金属イオンであると、有機オニウムイオン／アンモニウムイオン７ａに対してイオン化傾向が強いために後述する第二工程において、有機オニウムイオン／アンモニウムイオン７ａが微細化セルロース１のアニオン性官能基に対イオンとして結合しやすくなる。 Examples of alkaline aqueous solutions include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide (tetramethylammonium hydroxide, TMAH) aqueous solution, tetraethylammonium hydroxide (tetraethylammonium hydroxide , TEAH) aqueous solution, tetrabutylammonium hydroxide (tetrabutylammonium hydroxide, TBAH) aqueous solution, and organic onium compounds such as benzyltrimethylammonium hydroxide aqueous solution. A sodium hydroxide aqueous solution, a lithium hydroxide aqueous solution, and a potassium hydroxide aqueous solution are preferable from the viewpoint of cost.
A cationic substance contained in the alkaline aqueous solution used to maintain the pH during the oxidation reaction binds as a counterion to the carboxy group generated by the oxidation reaction. The cationic substance of the counter ion of the carboxy group of the TEMPO-oxidized cellulose is preferably alkali metal ions such as sodium ion, potassium ion and lithium ion, and metal ions such as alkaline earth metal such as magnesium ion and calcium ion. When the cationic substance of the counter ion of the carboxy group of the TEMPO-oxidized cellulose is a metal ion, the organic onium ion/ammonium ion 7a has a strong ionization tendency. easily binds to the anionic functional group of the micronized cellulose 1 as a counterion.
　Ｎ－オキシル化合物による酸化反応は、例えば、反応系にアルコールを添加することにより停止させることができる。このとき、反応系のｐＨは上記の範囲内に保つことが好ましい。添加するアルコールとしては、例えば、反応をすばやく終了させるためメタノール、エタノール、プロパノールなどの低分子量のアルコールが好ましく、反応により生成される副産物の安全性などから、エタノールが特に好ましい。 The oxidation reaction by the N-oxyl compound can be stopped, for example, by adding alcohol to the reaction system. At this time, it is preferable to keep the pH of the reaction system within the above range. As the alcohol to be added, for example, low-molecular-weight alcohols such as methanol, ethanol and propanol are preferable in order to quickly complete the reaction, and ethanol is particularly preferable in view of the safety of by-products produced by the reaction.
　酸化処理後の反応液は、そのまま微細化工程に供してもよいが、Ｎ－オキシル化合物等の触媒、不純物等を除去するために、反応液に含まれる酸化セルロースを回収し、洗浄液で洗浄することが好ましい。ＴＥＭＰＯ酸化セルロースの回収は、例えば、ガラスフィルターや２０μｍ孔径のナイロンメッシュを用いたろ過等の公知の方法により実施できる。ＴＥＭＰＯ酸化セルロースの洗浄に用いる洗浄液としては純水や塩酸等の酸性溶液が好ましい。純水を用いて洗浄した際にはＴＥＭＰＯ酸化セルロースのカルボキシ基の対イオンは置換されることなく、維持されるため、洗浄後のＴＥＭＰＯ酸化セルロースのカルボキシ基の対イオンは金属イオンとなる。また、塩酸等の酸を用いて洗浄することで、少なくとも一部の対イオンを除去し、ＴＥＭＰＯ酸化セルロースのカルボキシ基をＣＯＯＨとすることも可能である。
　ＴＥＭＰＯ酸化セルロースのカルボキシ基がＣＯＯＨ、あるいは対イオンが金属イオンであると、有機オニウムイオン／アンモニウムイオン７ａに対してイオン化傾向が強いために、後述する第二工程において、有機オニウムイオン／アンモニウムイオン７ａが微細化セルロース１のアニオン性官能基に対イオンとして結合しやすくなる。 The reaction solution after the oxidation treatment may be directly subjected to the micronization step, but in order to remove catalysts such as N-oxyl compounds, impurities, etc., the oxidized cellulose contained in the reaction solution is recovered and washed with a washing solution. is preferred. The TEMPO-oxidized cellulose can be collected by a known method such as filtration using a glass filter or a nylon mesh with a pore size of 20 μm. Pure water or an acidic solution such as hydrochloric acid is preferable as the cleaning liquid used for cleaning the TEMPO-oxidized cellulose. When washed with pure water, the counterions of the carboxyl groups of the TEMPO-oxidized cellulose are maintained without being replaced, so the counterions of the carboxyl groups of the TEMPO-oxidized cellulose after washing become metal ions. Also, by washing with an acid such as hydrochloric acid, it is possible to remove at least part of the counterions and convert the carboxy groups of the TEMPO-oxidized cellulose to COOH.
When the carboxy group of TEMPO-oxidized cellulose is COOH or the counter ion is a metal ion, the organic onium ion/ammonium ion 7a has a strong ionization tendency. easily binds to the anionic functional group of the micronized cellulose 1 as a counterion.
　得られたＴＥＭＰＯ酸化セルロースに対し解繊処理を行うと、３ｎｍ前後の均一な繊維幅を有するＴＥＭＰＯ酸化セルロースナノファイバー（以下、ＴＥＭＰＯ酸化ＣＮＦ、セルロースシングルナノファイバー、ＣＳＮＦとも称する。）が得られる。ＣＳＮＦを複合粒子５の微細化セルロース１の原料として用いると、その均一な構造に由来して、得られるＯ／Ｗ型エマルションの粒径も均一になりやすい。 When the obtained TEMPO-oxidized cellulose is defibrated, TEMPO-oxidized cellulose nanofibers (hereinafter also referred to as TEMPO-oxidized CNF, cellulose single nanofibers, CSNF) having a uniform fiber width of about 3 nm are obtained. When CSNF is used as a raw material for the micronized cellulose 1 of the composite particles 5, the resulting O/W emulsion tends to have a uniform particle size due to its uniform structure.
　以上のように、本実施形態で用いられるＣＳＮＦは、セルロース原料を酸化する工程と、微細化して分散液化する工程と、によって得ることができる。ＣＳＮＦに導入するカルボキシ基の含有量としては、０．１ｍｍｏｌ／ｇ以上５．０ｍｍｏｌ／ｇ以下が好ましく、０．５ｍｍｏｌ／ｇ以上２．０ｍｍｏｌ／ｇ以下がより好ましい。ここで、カルボキシ基量が０．１ｍｍｏｌ／ｇ未満であると、セルロースミクロフィブリル間に浸透圧効果による溶媒進入作用が働かないため、セルロースを微細化して均一に分散させることが困難となる傾向がある。また、カルボキシ基量が５．０ｍｍｏｌ／ｇを超えると化学処理に伴う副反応によりセルロースミクロフィブリルが低分子化するため、高結晶性の剛直な微細化セルロース１繊維とならず、Ｏ／Ｗ型エマルションの安定化剤として用いることが困難となる傾向がある。 As described above, the CSNF used in the present embodiment can be obtained by a process of oxidizing a cellulose raw material and a process of pulverizing and dispersing it. The content of carboxyl groups to be introduced into CSNF is preferably 0.1 mmol/g or more and 5.0 mmol/g or less, more preferably 0.5 mmol/g or more and 2.0 mmol/g or less. Here, when the amount of carboxyl groups is less than 0.1 mmol/g, there is a tendency that it becomes difficult to make the cellulose fine and uniformly disperse it, because the solvent penetration action due to the osmotic pressure effect does not work between the cellulose microfibrils. be. In addition, when the amount of carboxyl groups exceeds 5.0 mmol/g, the cellulose microfibrils become low-molecular-weight due to a side reaction accompanying the chemical treatment, so that highly crystalline, rigid, micronized cellulose 1 fibers cannot be obtained, and O/W type. It tends to be difficult to use as an emulsion stabilizer.
　酸化反応に用いるアルカリ水溶液として、金属アルカリの水溶液を用いる場合、セルロース原料を酸化し、ろ過洗浄、微細化して分散液化する工程と、によって得られたＣＳＮＦのカルボキシ基の対イオンは、ナトリウムイオン、カリウムイオン、リチウムイオン等のアルカリ金属や、マグネシウムイオンやカルシウムイオン等のアルカリ土類金属等の金属イオンとなる。ＣＳＮＦのカルボキシ基の対イオンが金属イオンである場合、ＣＳＮＦの表面は親水性が高い。
　物理的解繊処理のしやすさの観点から、ＣＳＮＦに対する金属イオンの結合量は、０．１ｍｍｏｌ／ｇ以上５．０ｍｍｏｌ／ｇ以下が好ましく、０．５ｍｍｏｌ／ｇ以上２．０ｍｍｏｌ／ｇ以下がより好ましい。ここで、金属イオンの結合量が０．１ｍｍｏｌ／ｇ未満であると、セルロースミクロフィブリル間に浸透圧効果による溶媒進入作用が働かないため、セルロースを微細化して均一に分散させることが困難となる傾向がある。また、カルボキシ基量が５．０ｍｍｏｌ／ｇを超えると化学処理に伴う副反応によりセルロースミクロフィブリルが低分子化するため、高結晶性の剛直な微細化セルロース１繊維構造をとることができず、Ｏ／Ｗ型エマルションの安定化剤として用いることが困難となる傾向がある。
　なお、金属イオン含有量は、様々な分析方法で調べることができ、例えば、電子線マイクロアナライザーを用いたＥＰＭＡ法、蛍光Ｘ線分析法、ＩＣＰ発光分光分析の元素分析によって簡易的に調べることができる。 When a metal alkali aqueous solution is used as the alkaline aqueous solution used for the oxidation reaction, the counter ion of the carboxyl group of CSNF obtained by the step of oxidizing the cellulose raw material, filtering and washing, and finely dispersing into a dispersion liquid is sodium ion, It becomes metal ions such as alkali metals such as potassium ions and lithium ions, and alkaline earth metals such as magnesium ions and calcium ions. When the counterion of the carboxy group of CSNF is a metal ion, the surface of CSNF is highly hydrophilic.
From the viewpoint of ease of physical fibrillation treatment, the amount of metal ions bound to CSNF is preferably 0.1 mmol/g or more and 5.0 mmol/g or less, and is preferably 0.5 mmol/g or more and 2.0 mmol/g or less. more preferred. Here, if the binding amount of metal ions is less than 0.1 mmol/g, the solvent penetration action due to the osmotic pressure effect does not work between the cellulose microfibrils, making it difficult to make the cellulose fine and uniformly disperse it. Tend. In addition, when the amount of carboxyl groups exceeds 5.0 mmol/g, the cellulose microfibrils become low-molecular-weight due to side reactions accompanying the chemical treatment, making it impossible to obtain a highly crystalline, rigid, micronized cellulose 1-fiber structure. It tends to be difficult to use as a stabilizer for O/W emulsions.
The metal ion content can be examined by various analytical methods. For example, the EPMA method using an electron beam microanalyzer, X-ray fluorescence analysis, and elemental analysis such as ICP emission spectrometry can be easily examined. can.
（第二工程）
　第二工程は、第一工程で得られた微細化セルロース分散液に、有機オニウム化合物／アミンを添加して攪拌し、微細化セルロース分散液に含まれる微細化セルロース１に有機オニウムイオン／アンモニウムイオン７ａを結合させる工程である。微細化セルロース分散液に有機オニウム化合物／アミンを添加して攪拌することで、短時間で簡便な方法にて有機オニウムイオン／アンモニウムイオン７ａが結合し、表面の少なくとも一部に疎水性が付与された微細化セルロース１を得ることができる。第一工程にて微細化セルロース１のアニオン性官能基に結合したカチオン性物質よりイオン化傾向の低い有機オニウムイオン／アンモニウムイオン７ａを用いることで、簡便に微細化セルロース１のアニオン性官能基の対イオンを交換することができる。 (Second step)
In the second step, an organic onium compound/amine is added to the micronized cellulose dispersion obtained in the first step and stirred to convert the micronized cellulose 1 contained in the micronized cellulose dispersion into organic onium ions/ammonium ions. This is the step of binding 7a. By adding the organic onium compound/amine to the micronized cellulose dispersion and stirring, the organic onium ions/ammonium ions 7a are bonded in a short and simple manner, and hydrophobicity is imparted to at least part of the surface. A finely divided cellulose 1 can be obtained. By using the organic onium ion/ammonium ion 7a having a lower ionization tendency than the cationic substance bound to the anionic functional group of the micronized cellulose 1 in the first step, the anionic functional group of the micronized cellulose 1 can easily be paired. Ions can be exchanged.
　前述のように、一般に、酸化反応時の反応系のｐＨは、水酸化ナトリウム水溶液等の金属アルカリの水溶液を用いるため、アニオン性官能基の対イオンのカチオン性物質はナトリウムイオン等の金属イオンとなる。金属イオンを対イオンとしたＴＥＭＰＯ酸化セルロースをろ過洗浄し、分散溶媒４に懸濁して物理的解繊処理することにより微細化セルロース１を得ることができる。
　一方、従来法による有機オニウムカチオン／アンモニウムイオン７ａが結合した微細化セルロースの作製は煩雑である。従来法では、酸化反応液に酸を添加して系内を酸性下に調整し、カルボン酸としてろ別した後に、懸濁した酸型のＴＥＭＰＯ酸化セルロースに、カルボキシ基と等量の有機オニウム化合物／アミンを添加して攪拌し、有機オニウムイオン／アンモニウムイオン７ａを結合させ、この懸濁液に物理的解繊処理を施して有機オニウムイオン／アンモニウムイオン７ａが結合したアニオン性官能基を有する微細化セルロース１を作製する。
　しかし、本実施形態においては、第一工程で得られた微細化セルロース１に第二工程で有機オニウム化合物／アミンを添加し、攪拌するという簡便な方法にて、有機オニウムイオン／アンモニウムイオン７ａが結合した微細化セルロース１を含む、イオン結合微細化セルロース分散液を得ることができる。これにより微細化セルロース１の一部に疎水性が付与される。 As described above, since an aqueous solution of metal alkali such as sodium hydroxide solution is generally used for the pH of the reaction system during the oxidation reaction, the cationic substance as the counter ion of the anionic functional group is a metal ion such as sodium ion. Become. Micronized cellulose 1 can be obtained by filtering and washing TEMPO-oxidized cellulose with metal ions as counter ions, suspending it in dispersion solvent 4, and subjecting it to physical fibrillation.
On the other hand, preparation of micronized cellulose to which organic onium cations/ammonium ions 7a are bound by conventional methods is complicated. In the conventional method, an acid is added to the oxidation reaction solution to adjust the inside of the system to be acidic, and the carboxylic acid is separated by filtration. /amine is added and stirred to bind organic onium ions/ammonium ions 7a, and this suspension is subjected to a physical defibration treatment to form fine particles having anionic functional groups to which organic onium ions/ammonium ions 7a are bound. A modified cellulose 1 is prepared.
However, in the present embodiment, organic onium ions/ammonium ions 7a are produced by a simple method of adding an organic onium compound/amine in the second step to the micronized cellulose 1 obtained in the first step and stirring. An ionically bound micronized cellulose dispersion containing bound micronized cellulose 1 can be obtained. Hydrophobicity is thereby imparted to a part of the micronized cellulose 1 .
　有機オニウム化合物／アミンを添加するアニオン性を有する微細化セルロース１は、カチオン性物質を対イオンとした塩を形成していてもよいが、カチオン性物質を含まなくてもよい。また、対イオンのカチオン性物質は、有機オニウムイオン／アンモニウムイオン７ａよりイオン化傾向が強いことが好ましい。カチオン性物質のイオン化傾向が強いほど、対イオン置換が効率よく進むため好ましい。対イオンのカチオン性物質としては、例えばナトリウムイオン、カリウムイオン、リチウムイオン等のアルカリ金属や、マグネシウムイオンやカルシウムイオン等のアルカリ土類金属等の金属イオンであることが好ましい。微細化セルロース１の少なくとも一部にアニオン性官能基に有機オニウムイオン／アンモニウムイオン７ａを結合させた後も、一部のアニオン性官能基にカチオン性物質が残留しても構わない。
　アニオン性官能基に残留するカチオン性物質の量は特に限定されないが、微細化セルロース１のアニオン性官能基に対して、０．９５当量以下、好ましくは０．９０当量以下、より好ましくは０．８０当量以下である。残留するカチオン性物質の量が０．９５当量を超えるとエマルション安定が低くなるため、収率が下がり、粒子径分布が広くなることがある。
　微細化セルロース１におけるカチオン性物質の含有量は様々な分析方法で調べることができる。例えば、カチオン性物質が金属である場合は、電子線マイクロアナライザーを用いたＥＰＭＡ法や、蛍光Ｘ線分析法による元素分析等を簡易的な方法として例示できる。アニオン性を有する微細化セルロース１からカチオン性物質を除去する方法としては、微細化セルロース１を酸性下で繰り返し洗浄した後に純水で水洗を繰り返す精製し、再度前述の物理的解繊処理を施すことを例示できる。 The anionic finely divided cellulose 1 to which an organic onium compound/amine is added may form a salt with a cationic substance as a counterion, but may not contain a cationic substance. Moreover, the cationic substance of the counter ion preferably has a stronger ionization tendency than the organic onium ion/ammonium ion 7a. The stronger the ionization tendency of the cationic substance, the more efficiently counter ion substitution proceeds, which is preferable. The cationic substance of the counter ion is preferably, for example, an alkali metal ion such as sodium ion, potassium ion or lithium ion, or a metal ion such as alkaline earth metal ion such as magnesium ion or calcium ion. Even after binding organic onium ions/ammonium ions 7a to the anionic functional groups of at least a portion of the micronized cellulose 1, the cationic substance may remain in a portion of the anionic functional groups.
Although the amount of the cationic substance remaining in the anionic functional group is not particularly limited, it is 0.95 equivalent or less, preferably 0.90 equivalent or less, more preferably 0.95 equivalent or less, relative to the anionic functional group of the micronized cellulose 1. 80 equivalents or less. When the amount of residual cationic material exceeds 0.95 equivalents, the emulsion stability is low, which can lead to low yields and broad particle size distributions.
The content of cationic substances in the micronized cellulose 1 can be examined by various analytical methods. For example, when the cationic substance is a metal, an EPMA method using an electron beam microanalyzer, elemental analysis by fluorescent X-ray analysis, and the like can be exemplified as simple methods. As a method for removing the cationic substance from the micronized cellulose 1 having anionic properties, the micronized cellulose 1 is repeatedly washed under acidic conditions, then purified by repeatedly washing with pure water, and then subjected to the physical defibration treatment described above again. I can give an example.
　微細化セルロース分散液への有機アンモニウム化合物／アミンの添加量としては、微細化セルロース１に含まれるアニオン性官能基に対して０．０１当量以上２当量以下であることが好ましい。特に、添加量が０．０２当量以上１．８当量以下であると、十分に微細化セルロース１の表面を疎水化することができ、安定したＯ／Ｗ型エマルションを形成でき、粒子径の均一な複合粒子５を高収率に得ることができるため、好ましい。有機オニウム化合物／アミンの添加量が０．０１当量未満であると、微細化セルロース１の表面の疎水化が十分ではなく、粒子径にばらつきが生じやすく、収率が下がることもある。一方、２当量を超えると、有機オニウム化合物／アミンの過剰添加により微細化セルロース１の分解や分散媒への親和性低下が生じる場合があり、好ましくない。 The amount of the organic ammonium compound/amine added to the micronized cellulose dispersion is preferably 0.01 equivalent or more and 2 equivalents or less with respect to the anionic functional group contained in the micronized cellulose 1. In particular, when the amount added is 0.02 equivalent or more and 1.8 equivalent or less, the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, and the particle size is uniform. It is preferable because the composite particles 5 can be obtained with a high yield. If the amount of the organic onium compound/amine added is less than 0.01 equivalent, the hydrophobization of the surface of the micronized cellulose 1 is not sufficient, and the particle size tends to vary, and the yield may decrease. On the other hand, when the amount exceeds 2 equivalents, excessive addition of the organic onium compound/amine may cause decomposition of the micronized cellulose 1 or decrease in affinity to the dispersion medium, which is not preferable.
　微細化セルロース１における有機オニウムイオン／アンモニウムイオン７ａの平均結合量は、アニオン性官能基に対して０．０１当量以上、好ましくは０．０５当量以上であり、好ましくは０．８当量以下、好ましくは０．５０当量以下、より好ましくは０．３０当量以下である。有機オニウムイオン／アンモニウムイオン７ａの平均結合量がこの範囲であると、微細化セルロース１の分散性、安定性が良好となる。
　有機オニウムイオン／アンモニウムイオン７ａの平均結合量（当量）は、微細化セルロースあたりの有機オニウムイオン／アンモニウムイオン７ａの平均結合量（ｍｍоｌ／ｇ）をＡ、微細化セルロースあたりのアニオン性官能基量（ｍｍоｌ／ｇ）をＢとすると、Ａ／Ｂにて計算することができる。
　平均結合量が０．０１当量以上０．８当量以下であると、十分に微細化セルロース１の表面を疎水化することができ、安定したＯ／Ｗ型エマルションを形成でき、粒径が小さく、均一な複合粒子５を高収率に得ることができるため、好ましい。有機オニウムイオン／アンモニウムイオン７ａの結合量が０．０１当量未満であると、微細化セルロース１の表面の疎水化が十分ではなく、粒径にばらつきが生じやすく、収率が下がることもある。一方、０．８当量を超えると、有機オニウムイオン／アンモニウムイオン７ａにより微細化セルロース１の分解や分散媒への親和性低下が生じる場合があり、好ましくない。 The average binding amount of the organic onium ion/ammonium ion 7a in the micronized cellulose 1 is 0.01 equivalent or more, preferably 0.05 equivalent or more, preferably 0.8 equivalent or less, and preferably 0.8 equivalent or less with respect to the anionic functional group. is 0.50 equivalents or less, more preferably 0.30 equivalents or less. When the average bonding amount of the organic onium ion/ammonium ion 7a is within this range, the dispersibility and stability of the micronized cellulose 1 are improved.
The average binding amount (equivalent) of the organic onium ion/ammonium ion 7a is defined by A being the average binding amount (mmol/g) of the organic onium ion/ammonium ion 7a per micronized cellulose, and the amount of anionic functional groups per micronized cellulose. If (mmol/g) is B, it can be calculated as A/B.
When the average binding amount is 0.01 equivalent or more and 0.8 equivalent or less, the surface of the micronized cellulose 1 can be sufficiently hydrophobized, a stable O/W emulsion can be formed, the particle size is small, This is preferable because uniform composite particles 5 can be obtained at a high yield. If the binding amount of the organic onium ion/ammonium ion 7a is less than 0.01 equivalent, the surface of the micronized cellulose 1 is not sufficiently hydrophobized, and the particle size tends to vary, resulting in a decrease in yield. On the other hand, if it exceeds 0.8 equivalents, the organic onium ion/ammonium ion 7a may decompose the micronized cellulose 1 or lower the affinity for the dispersion medium, which is not preferable.
　有機オニウム化合物／アミンの種類は、１種類でもよく、２種類以上を混合して用いてもよい。特に、有機オニウムまたはアミンを構成する水酸基または炭化水素基の構造が異なるものを混合して用いてもよい。或いは、炭化水素基が直鎖状であっても分岐状であってもよい。 The type of organic onium compound/amine may be one type, or two or more types may be mixed and used. In particular, organic oniums or amines having different structures of hydroxyl groups or hydrocarbon groups may be mixed and used. Alternatively, the hydrocarbon group may be linear or branched.
　微細化セルロース１に有機オニウム化合物／アミンを添加する際の分散溶媒４としては水が好適であり、水を５０％以上含むことが好ましい。分散溶媒４における水の割合が５０％以下になると、後述する第三工程において、液状のコア粒子前駆体２のエマルションの安定が阻害される。
　分散液における微細化セルロース１の割合は、０．１％以上１０％未満が好ましい。０．１％未満であると、第一工程においてのセルロース原料の解繊時に溶媒過多となり生産性を損なうため好ましくない。また、後述する第三工程において安定したＯ／Ｗ型エマルションを形成することが困難となり、複合粒子５の収率が下がり、粒子径にばらつきが生じやすくなる。１０％以上になると、前述のセルロース原料の解繊に伴い懸濁液が急激に増粘し、均一な解繊処理が困難となるため好ましくない。また、微細化セルロース１の分散液の粘度が高くなるため、第三工程においてＯ／Ｗ型エマルションを形成するのが困難となる。 Water is suitable as the dispersion solvent 4 when the organic onium compound/amine is added to the micronized cellulose 1, and it is preferable that the water content is 50% or more. When the proportion of water in the dispersion solvent 4 is 50% or less, the stability of the emulsion of the liquid core particle precursor 2 is hindered in the third step described later.
The proportion of micronized cellulose 1 in the dispersion is preferably 0.1% or more and less than 10%. If it is less than 0.1%, the amount of the solvent becomes excessive when defibrating the cellulose raw material in the first step, which impairs productivity, which is not preferable. In addition, it becomes difficult to form a stable O/W emulsion in the third step described later, the yield of the composite particles 5 decreases, and the particle diameter tends to vary. If it is 10% or more, the suspension will rapidly thicken as the cellulose raw material is defibrated, making it difficult to perform a uniform fibrillation treatment, which is not preferable. Moreover, since the viscosity of the dispersion liquid of micronized cellulose 1 increases, it becomes difficult to form an O/W emulsion in the third step.
　有機オニウムイオン／アンモニウムイオン７ａが結合した微細化セルロース１を含む微細化セルロース分散液を得る方法は、特に限定されないが、有機オニウム化合物／アミンを予め水に溶解させた水溶液を、微細化セルロース１の分散液に添加し、攪拌することで当該分散液を得てもよい。有機オニウム化合物／アミンを溶解させた水溶液の有機オニウム化合物／アミンの濃度は、特に限定されないが、０．０１Ｍ以上５．０Ｍ以下であることが好ましい。 The method of obtaining the micronized cellulose dispersion containing the micronized cellulose 1 to which the organic onium ions/ammonium ions 7a are bound is not particularly limited. may be added to the dispersion and stirred to obtain the dispersion. Although the concentration of the organic onium compound/amine in the aqueous solution in which the organic onium compound/amine is dissolved is not particularly limited, it is preferably 0.01M or more and 5.0M or less.
　有機オニウム化合物／アミンを添加する微細化セルロース１の分散液のｐＨは特に限定されず、４以上１２以下が好ましく、より好ましくはｐＨ６以上１０以下である。ｐＨが６以上であると微細化セルロース１のアニオン性官能基がイオン化しやすく、浸透圧効果で微細化セルロース１の繊維間に溶媒が浸入しやすくなり、微細化セルロース１の分散安定性が高まる。また、ｐＨが１０以下であると、有機オニウム化合物／アミン７ａを加えた際のｐＨ上昇を抑えることができ、微細化セルロース１のピーリング反応やアルカリ加水分解による低分子化を抑制できる。
　微細化セルロース１に有機オニウム化合物／アミンを添加した後のｐＨは４以上１２以下が好ましい。特に、ｐＨ７以上１２以下のアルカリ性とすると、微細化セルロース１のアニオン性官能基がイオン化するため、浸透圧効果で微細化セルロース１の繊維間に溶媒が浸入しやすくなり、微細化セルロース１の分散安定性が高まる。
　ｐＨ４未満の場合は、微細化セルロース１の分散性が低下する。一方、ｐＨ１２を超えると、アニオン性を有する微細化セルロース１に、ピーリング反応やアルカリ加水分解による低分子量化が生じたり、末端アルデヒドや二重結合形成によって分散液の黄変が促進されたりするため、好ましくない。 The pH of the dispersion liquid of micronized cellulose 1 to which the organic onium compound/amine is added is not particularly limited, and is preferably 4 or more and 12 or less, more preferably 6 or more and 10 or less. When the pH is 6 or higher, the anionic functional groups of the micronized cellulose 1 are likely to be ionized, and the osmotic pressure effect makes it easier for the solvent to penetrate between the fibers of the micronized cellulose 1, increasing the dispersion stability of the micronized cellulose 1. . Further, when the pH is 10 or less, it is possible to suppress the increase in pH when adding the organic onium compound/amine 7a, and it is possible to suppress the peeling reaction of the micronized cellulose 1 and the reduction in molecular weight due to alkaline hydrolysis.
The pH after adding the organic onium compound/amine to the micronized cellulose 1 is preferably 4 or more and 12 or less. In particular, when the pH is 7 or more and 12 or less alkaline, the anionic functional group of the micronized cellulose 1 is ionized, so that the solvent easily penetrates between the fibers of the micronized cellulose 1 due to the osmotic pressure effect, and the micronized cellulose 1 is dispersed. Increased stability.
If the pH is less than 4, the dispersibility of the micronized cellulose 1 is lowered. On the other hand, when the pH exceeds 12, the anionic finely divided cellulose 1 undergoes a peeling reaction or alkali hydrolysis, resulting in a low molecular weight, and terminal aldehydes and double bond formation accelerate yellowing of the dispersion. , unfavorable.
　微細化セルロース１に有機オニウム化合物／アミンを添加し、攪拌する際の温度は特に限定されないが、４℃以上８０℃以下が好ましく、１０℃以上７０℃以下がより好ましい。温度が４℃未満であると、対イオンの交換効率が悪くなる。温度が８０℃を超えるとセルロースが低分子化して高結晶性の剛直な微細化セルロース１の繊維構造が崩壊し、Ｏ／Ｗ型エマルションの安定化剤として用いることが困難となる傾向がある。攪拌時間は、温度、所望のアニオン性官能基量等を考慮して適宜設定でき、特に限定されないが、通常１０分～５時間程度である。 Although the temperature at which the organic onium compound/amine is added to the micronized cellulose 1 and stirred is not particularly limited, it is preferably 4°C or higher and 80°C or lower, more preferably 10°C or higher and 70°C or lower. If the temperature is less than 4° C., the exchange efficiency of the counter ion will be poor. If the temperature exceeds 80° C., the cellulose tends to have a low molecular weight and the fibrous structure of the highly crystalline rigid micronized cellulose 1 collapses, making it difficult to use it as a stabilizer for O/W emulsions. The stirring time can be appropriately set in consideration of the temperature, the desired amount of anionic functional groups, etc., and is not particularly limited, but is usually about 10 minutes to 5 hours.
　本実施形態における有機オニウム化合物は、化１に示す構造式のカチオン構造を有する。 The organic onium compound in this embodiment has a cation structure of the structural formula shown in Chemical formula 1.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
　上記構造式中において、Ｍは窒素原子、リン原子、水素原子、硫黄原子のいずれかであり、Ｒ１、Ｒ２、Ｒ３、およびＲ４は、水素原子、炭化水素基、ヘテロ原子を含む炭化水素基のいずれかである。
　例えば、Ｍが窒素原子であり、Ｒ１、Ｒ２、Ｒ３及びＲ４がいずれも水素原子の場合、有機オニウム化合物はアンモニアである。Ｒ１、Ｒ２、Ｒ３、Ｒ４のうち３つが水素原子の場合は第１級アミン、２つの場合は第２級アミン、１つの場合は第３級アミン、０個の場合は第４級アミンとなり、いずれも本実施形態における有機オニウム化合物である。へテロ原子を含む炭化水素基としては、アルキル基、アルキレン基、オキシアルキレン基、アラルキル基、アリール基、芳香族基等を例示できる。Ｒ１、Ｒ２、Ｒ３、およびＲ４が環を形成していてもよい。 In the above structural formula, M is a nitrogen atom, a phosphorus atom, a hydrogen atom, or a sulfur atom, and R1, R2, R3, and R4 are a hydrogen atom, a hydrocarbon group, or a hydrocarbon group containing a hetero atom. Either.
For example, when M is a nitrogen atom and R1, R2, R3 and R4 are all hydrogen atoms, the organic onium compound is ammonia. When three of R1, R2, R3, and R4 are hydrogen atoms, it is a primary amine, two when it is a secondary amine, one when it is a tertiary amine, and zero when it is a quaternary amine, Both are organic onium compounds in the present embodiment. Examples of hydrocarbon groups containing heteroatoms include alkyl groups, alkylene groups, oxyalkylene groups, aralkyl groups, aryl groups, and aromatic groups. R1, R2, R3 and R4 may form a ring.
　上記構造式中において、Ｍが窒素原子である第４級アンモニウム化合物としては、例えば、テトラエチルアンモニウムヒドロキシド（ＴＥＡＨ）、テトラエチルアンモニウムクロリド、テトラブチルアンモニウムヒドロキシド（ＴＢＡＨ）、テトラブチルアンモニウムクロリド、ジデシルジメチルアンモニウムクロリド、ラウリルトリメチルアンモニウムクロリド、ジラウリルジメチルクロリド、ステアリルトリメチルアンモニウムクロリド、ジステアリルジメチルアンモニウムクロリド、セチルトリメチルアンモニウムクロリド、アルキルベンジルジメチルアンモニウムクロリド、ココナットアミンが挙げられる。
　特に、ジデシルジメチルアンモニウムクロリド、セチルトリメチルアンモニウムクロリド、アルキルベンジルジメチルアンモニウムクロリドを用いることで、抗菌性を付与できるため、好ましい。 Examples of quaternary ammonium compounds in which M is a nitrogen atom in the above structural formula include tetraethylammonium hydroxide (TEAH), tetraethylammonium chloride, tetrabutylammonium hydroxide (TBAH), tetrabutylammonium chloride, didecyl dimethylammonium chloride, lauryltrimethylammonium chloride, dilauryldimethylchloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, cetyltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, coconut amine.
In particular, it is preferable to use didecyldimethylammonium chloride, cetyltrimethylammonium chloride, or alkylbenzyldimethylammonium chloride, since antibacterial properties can be imparted.
　上記構造式中において、Ｍがリン原子である第４級ホスホニウム化合物としては、例えば、テトラメチルホスホニウムヒドロキシド、テトラエチルホスホニウムヒドロキシド、テトラプロピルホスホニウムヒドロキシド、テトラブチルホスホニウムヒドロキシド、ベンジルトリメチルホスホニウムヒドロキシド、ベンジルトリエチルホスホニウムヒドロキシド、ヘキサデシルトリメチルホスホニウムヒドロキシド等のホスホニウム等が挙げられる。 Examples of quaternary phosphonium compounds in which M is a phosphorus atom in the above structural formula include tetramethylphosphonium hydroxide, tetraethylphosphonium hydroxide, tetrapropylphosphonium hydroxide, tetrabutylphosphonium hydroxide, and benzyltrimethylphosphonium hydroxide. , benzyltriethylphosphonium hydroxide, hexadecyltrimethylphosphonium hydroxide and the like.
　本実施形態における第１級アミン、第２級アミン、第３級アミンは、それぞれ化２の式（１）、（２）、（３）に示す構造を有する。なお、これらがイオン化してカチオン構造のアンモニウムイオンとなった際の構造は、それぞれ（１）’、（２）’、（３）’となる。（１）’は第１級アンモニウムイオン、（２）’は第２級アンモニウムイオン、（３）’は第３級アンモニウムイオンである。 The primary amine, secondary amine, and tertiary amine in the present embodiment have the structures shown in formulas (1), (2), and (3) of chemical formula 2, respectively. The structures when these are ionized to become ammonium ions with a cationic structure are (1)', (2)', and (3)', respectively. (1)' is a primary ammonium ion, (2)' is a secondary ammonium ion, and (3)' is a tertiary ammonium ion.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　式（１）から（３）’において、Ｒ１～Ｒ６は、炭化水素基、ヘテロ原子を含む炭化水素基のいずれかである。 In formulas (1) to (3)', R1 to R6 are either a hydrocarbon group or a hydrocarbon group containing a heteroatom.
　第１級アミン、第２級アミン、第３級アミンとしては、メチルアミン、エチルアミン、プロピルアミン、ブチルアミン、ｎ－オクチルアミン、ジメチルアミン、ジエチルアミン、ジプロピルアミン、ジブチルアミン、へキシルアミン、２－エチルへキシルアミン、ジヘキシルアミン、トリメチルアミン、トリエチルアミン、トリプロピルアミン、トリブチルアミン、トリオクチルアミン、トリへキシルアミン、ジオクチルアミン、ドデシルアミン、ステアリルアミン、オレイルアミンアミノ変性シリコーン化合物、ポリエーテルアミン、ポリエチレングリコールアミン（ＰＥＧ－ＮＨ２）、エチレンオキサイド／プロピレンオキサイド（ＥＯ／ＰＯ）共重合部を有するアミンなどを例示することができる。 Primary amine, secondary amine and tertiary amine include methylamine, ethylamine, propylamine, butylamine, n-octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, hexylamine and 2-ethylamine. Hexylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trioctylamine, trihexylamine, dioctylamine, dodecylamine, stearylamine, oleylamine amino-modified silicone compound, polyetheramine, polyethylene glycolamine (PEG- NH 2 ), amines having an ethylene oxide/propylene oxide (EO/PO) copolymer moiety, and the like.
　有機オニウム化合物／アミンのカチオン構造の対イオンは特に限定されない。有機オニウム化合物のカチオン構造の対イオンとしては、硝酸イオン、硫酸イオン、水酸化物イオン、塩化物イオン、臭化物イオン、ヨウ化物イオン等が挙げられる。特に、カチオン構造の対イオンが塩化物イオンや臭化物イオンである塩の有機オニウム化合物を用いると、微細化セルロース分散液に添加してもｐＨの上昇を抑えることができ、ｐＨをコントロールしやすい。また、有機オニウム化合物は、水和物であってもよい。
　第二工程では、有機オニウム化合物に加えて、アルカリ金属やアルカリ土類金属等の金属塩を含む無機アルカリが添加されてもよい。 The counter ion of the cationic structure of the organic onium compound/amine is not particularly limited. Examples of the counter ion of the cation structure of the organic onium compound include nitrate ion, sulfate ion, hydroxide ion, chloride ion, bromide ion, iodide ion and the like. In particular, the use of a salt organic onium compound in which the counter ion of the cationic structure is a chloride ion or a bromide ion can suppress the increase in pH even when added to the finely divided cellulose dispersion, making it easy to control the pH. Also, the organic onium compound may be a hydrate.
In the second step, an inorganic alkali containing a metal salt such as an alkali metal or an alkaline earth metal may be added in addition to the organic onium compound.
　微細化セルロース１に有機オニウム化合物／アミンを添加して得られた有機オニウムイオン／アンモニウムイオン７ａを結合した微細化セルロース１は、金属イオンを対イオンとする無機アルカリを用いた場合よりも分散液の分散安定性が良好である。これは、有機オニウム化合物／アミンを用いた方が、微細化セルロース１が有するアニオン性部位の対イオンのイオン径が大きいため、分散溶媒４中で微細化セルロース１同士をより引き離す効果が大きいためと考えられる。さらに、分散液として有機オニウム化合物／アミンを含むと、無機アルカリと比べて分散液の粘度とチキソ性を低下させることができ、後述の第三工程におけるエマルション化のしやすさとその後のハンドリングにおいて有利になる。さらに、有機オニウム化合物／アミンとイオン結合により相互作用した微細化セルロース１は、有機オニウムイオン／アンモニウムイオン７ａに基づく立体斥力または疎水化作用によって親水性が低下する。これにより後述の第三工程において液状のコア粒子前駆体２のエマルション液滴への親和性が高まり、液滴６の安定性が向上する。 The micronized cellulose 1 obtained by adding an organic onium compound/amine to the micronized cellulose 1 and combining the organic onium ion/ammonium ion 7a has a higher dispersion than when an inorganic alkali having a metal ion as a counter ion is used. good dispersion stability. This is because the use of an organic onium compound/amine has a larger ion diameter of the counter ion of the anionic site of the micronized cellulose 1, and thus has a greater effect of separating the micronized cellulose 1 from each other in the dispersion solvent 4. it is conceivable that. Furthermore, if the dispersion contains an organic onium compound/amine, the viscosity and thixotropy of the dispersion can be reduced compared to inorganic alkali, which is advantageous in terms of ease of emulsification in the third step described below and subsequent handling. become. Furthermore, the micronized cellulose 1 interacting with the organic onium compound/amine through ionic bonds is reduced in hydrophilicity due to the steric repulsion or hydrophobizing action based on the organic onium ion/ammonium ion 7a. As a result, the affinity of the liquid core particle precursor 2 to the emulsion droplets is increased in the third step, which will be described later, and the stability of the droplets 6 is improved.
　得られた微細化セルロース分散液は、必要に応じて、本発明の効果を損なわない範囲で、セルロースおよびｐＨ調整に用いた成分以外の他の成分を含有してもよい。他の成分としては、特に限定されず、複合粒子５の用途等に応じて、公知の添加剤から適宜選択できる。具体的には、アルコキシシラン等の有機金属化合物またはその加水分解物、無機層状化合物、無機針状鉱物、消泡剤、無機系粒子、有機系粒子、潤滑剤、酸化防止剤、帯電防止剤、紫外線吸収剤、安定剤、磁性粉、配向促進剤、可塑剤、架橋剤、磁性体、医薬品、農薬、香料、接着剤、酵素、顔料、染料、消臭剤、金属、金属酸化物、無機酸化物等が挙げられる。 The obtained micronized cellulose dispersion may contain other ingredients other than cellulose and the ingredients used for adjusting the pH, if necessary, within a range that does not impair the effects of the present invention. Other components are not particularly limited, and can be appropriately selected from known additives according to the use of the composite particles 5 and the like. Specifically, organic metal compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic acicular minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, UV absorbers, stabilizers, magnetic powders, orientation accelerators, plasticizers, cross-linking agents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxidation things, etc.
（第三工程）
　第三工程は、第二工程で得られた有機オニウムイオン／アンモニウムイオン７ａが結合した微細化セルロースの分散液中において、コア粒子前駆体２を含む液滴６をエマルションとして安定化させる工程である。 (Third step)
The third step is a step of stabilizing the liquid droplets 6 containing the core particle precursor 2 as an emulsion in the dispersion liquid of the micronized cellulose to which the organic onium ions/ammonium ions 7a are bonded obtained in the second step. .
　具体的には、第二工程で得られた分散液（水相、分散相）にコア粒子前駆体２を含有する液体状の油相（分散相）を添加し、図２に示すように、コア粒子前駆体２を含む液滴６を分散液中に分散させる。これにより、液滴６の表面は微細化セルロース１によって被覆され、被覆層１０によって安定化されたＯ／Ｗ型エマルションが作製される。第二工程で得られた有機オニウムイオン／アンモニウムイオン７ａが結合し、表面の少なくとも一部が疎水化された微細化セルロース１を用いることにより、幅広い種類のコア粒子前駆体２を用いても、液滴６に微細化セルロース１が安定的に吸着し、安定したＯ／Ｗ型エマルションを得ることができる。 Specifically, a liquid oil phase (dispersed phase) containing the core particle precursor 2 is added to the dispersion (aqueous phase, dispersed phase) obtained in the second step, and as shown in FIG. Droplets 6 containing the core particle precursor 2 are dispersed in the dispersion liquid. As a result, the surfaces of the droplets 6 are coated with the micronized cellulose 1, and an O/W emulsion stabilized by the coating layer 10 is produced. By using the micronized cellulose 1 obtained in the second step to which the organic onium ions/ammonium ions 7a are bonded and at least a portion of the surface of which is hydrophobized, even if a wide variety of core particle precursors 2 are used, The micronized cellulose 1 is stably adsorbed on the droplets 6, and a stable O/W emulsion can be obtained.
　Ｏ／Ｗ型エマルションを作製する方法としては特に限定されないが、一般的な乳化処理、例えば各種ホモジナイザー処理や機械攪拌処理を用いることができ、具体的には高圧ホモジナイザー、超高圧ホモジナイザー、万能ホモジナイザー、ボールミル、ロールミル、カッターミル、遊星ミル、ジェットミル、アトライター、グラインダー、ジューサーミキサー、ホモミキサー、超音波ホモジナイザー、ナノジナイザー、水中対向衝突、ペイントシェイカーなどの機械的処理が挙げられる。また、複数の機械的処理を組み合わせて用いてもよい。 The method for producing an O/W emulsion is not particularly limited, but general emulsification treatments such as various homogenizer treatments and mechanical stirring treatments can be used. Mechanical treatments such as ball mills, roll mills, cutter mills, planetary mills, jet mills, attritors, grinders, juicer mixers, homomixers, ultrasonic homogenizers, nanogenizers, underwater counter-impingement, and paint shakers. Also, a plurality of mechanical treatments may be used in combination.
　例えば超音波ホモジナイザーを用いる場合、第一工程にて得られた微細化セルロース分散液に対し重合性モノマーを添加して混合溶媒とし、混合溶媒に超音波ホモジナイザーの先端を挿入して超音波処理を実施する。超音波ホモジナイザーの処理条件としては特に限定されないが、例えば周波数は２０ｋＨｚ以上が一般的であり、出力は１０Ｗ／ｃｍ２以上が一般的である。処理時間についても特に限定されないが、通常１０秒から１時間程度である。 For example, when using an ultrasonic homogenizer, a polymerizable monomer is added to the micronized cellulose dispersion obtained in the first step to form a mixed solvent, and the tip of the ultrasonic homogenizer is inserted into the mixed solvent to perform ultrasonic treatment. implement. The processing conditions of the ultrasonic homogenizer are not particularly limited, but, for example, the frequency is generally 20 kHz or higher and the output is generally 10 W/cm 2 or higher. The treatment time is also not particularly limited, but is usually about 10 seconds to 1 hour.
　上記超音波処理により、分散液中にコア粒子前駆体２を含む液滴６が分散してエマルション化が進行し、さらに液滴６と分散液との液／液界面に選択的に微細化セルロース１が吸着することで、液滴６が微細化セルロース１で被覆されＯ／Ｗ型エマルションとして安定した構造を形成する。このように、液／液界面に固体物が吸着して安定化したエマルションは、学術的には「ピッカリングエマルション」と呼称されている。前述のように微細化セルロース繊維によってピッカリングエマルションが形成されるメカニズムは定かではないが、セルロースはその分子構造において水酸基に由来する親水性サイトと炭化水素基に由来する疎水性サイトとを有することから両親媒性を示すため、両親媒性に由来して疎水性モノマーと親水性溶媒の液／液界面に吸着すると考えられる。 By the above ultrasonic treatment, the droplets 6 containing the core particle precursor 2 are dispersed in the dispersion liquid, emulsification progresses, and further, the finely divided cellulose is selectively formed at the liquid/liquid interface between the droplets 6 and the dispersion liquid. By adsorbing 1, droplets 6 are coated with micronized cellulose 1 to form a stable structure as an O/W emulsion. Such an emulsion stabilized by adsorption of a solid substance to the liquid/liquid interface is academically called a "Pickering emulsion". As mentioned above, the mechanism by which a Pickering emulsion is formed by micronized cellulose fibers is not clear, but cellulose has hydrophilic sites derived from hydroxyl groups and hydrophobic sites derived from hydrocarbon groups in its molecular structure. Since it exhibits amphiphilicity from , it is thought that it adsorbs to the liquid/liquid interface between the hydrophobic monomer and the hydrophilic solvent due to the amphiphilicity.
　Ｏ／Ｗ型エマルション構造は、光学顕微鏡観察により確認できる。Ｏ／Ｗ型エマルションの粒径サイズは特に限定されないが、通常０．１μｍ～１０００μｍ程度であることが好ましい。エマルションの平均粒子径は０．１μｍ以上１００μｍ以下であることが好ましく、より好ましくは０．１μｍ以上５０μｍ以下、更に好ましくは０．１μｍ以上２０μｍ以下である。有機オニウムイオン／アンモニウムイオン７ａが結合した微細化セルロース１を用いることにより、多くのコア粒子前駆体２にて、安定して微小な液滴６を得ることができ、エマルションの平均粒子径が小さくなる。
　エマルションの平均粒子径は、特に限定されないが、光学顕微鏡にて１００個のエマルション液滴の粒子径を測定し、平均することで算出できる。 The O/W emulsion structure can be confirmed by optical microscope observation. Although the particle size of the O/W emulsion is not particularly limited, it is usually preferably about 0.1 μm to 1000 μm. The average particle size of the emulsion is preferably 0.1 μm or more and 100 μm or less, more preferably 0.1 μm or more and 50 μm or less, and still more preferably 0.1 μm or more and 20 μm or less. By using the micronized cellulose 1 bound with organic onium ions/ammonium ions 7a, fine droplets 6 can be stably obtained with many core particle precursors 2, and the average particle size of the emulsion is small. Become.
The average particle size of the emulsion is not particularly limited, but can be calculated by measuring the particle size of 100 emulsion droplets with an optical microscope and averaging them.
　Ｏ／Ｗ型エマルション構造において、液滴６の表層に形成された被覆層１０の厚みは特に限定されないが、通常３ｎｍ～１０００ｎｍ程度である。被覆層１０の厚みは、例えばクライオＴＥＭ（Transmission Electron Microscope）を用いて計測することができる。 In the O/W emulsion structure, the thickness of the coating layer 10 formed on the surface layer of the droplet 6 is not particularly limited, but is usually about 3 nm to 1000 nm. The thickness of the coating layer 10 can be measured using, for example, a cryo-TEM (Transmission Electron Microscope).
　コア粒子前駆体２を含有する液体状の油相（分散相）は、コア粒子前駆体２を含有し、液滴６としてＯ／Ｗ型エマルションを形成することができればよく、Ｏ／Ｗ型エマルションを安定的に形成するためには、前記微細化セルロース１の分散液と相溶せず、疎水性であることが好ましい。また、前記コア粒子前駆体２は、化学的な変化あるいは物理化学的な変化により固体化してコア粒子３を形成する前駆体である。
　コア粒子前駆体２としては、例えば、（Ａ）重合性を有する化合物、（Ｂ）加熱により溶融した溶融ポリマー、（Ｃ）溶媒に溶解した溶解ポリマー、を用いることもできる。 The liquid oil phase (dispersed phase) containing the core particle precursor 2 may contain the core particle precursor 2 and form an O/W emulsion as the droplets 6. In order to stably form , it is preferably incompatible with the dispersion liquid of the micronized cellulose 1 and hydrophobic. The core particle precursor 2 is a precursor that solidifies to form the core particles 3 by chemical change or physicochemical change.
As the core particle precursor 2, for example, (A) a polymerizable compound, (B) a molten polymer melted by heating, and (C) a dissolved polymer dissolved in a solvent can be used.
　（Ａ）重合性を有する化合物としては、重合性官能基を有するモノマー（重合性モノマー）や、重合性官能基を有するオリゴマー（重合性オリゴマー）、重合性官能基を有するポリマー（重合性ポリマー）等、重合反応により固体のポリマーを形成できるものが挙げられる。（Ｂ）溶融ポリマーとしては、熱可塑性ポリマーであり加熱により液体状に溶融し、相転移して室温下において固体となるものが挙げられる。（Ｃ）溶解ポリマーとしては、非硬化性ポリマーであり溶剤により液体状に溶解し、溶剤除去により室温下において固体となるものが挙げられる。 (A) The compound having polymerizability includes a monomer having a polymerizable functional group (polymerizable monomer), an oligomer having a polymerizable functional group (polymerizable oligomer), and a polymer having a polymerizable functional group (polymerizable polymer). and the like, which can form a solid polymer by a polymerization reaction. (B) Melting polymers include those that are thermoplastic polymers that melt into a liquid state by heating and undergo a phase transition to become a solid at room temperature. The (C) dissolved polymer includes a non-curable polymer that dissolves into a liquid state with a solvent and becomes solid at room temperature when the solvent is removed.
　上記（Ａ）について、重合性モノマーは少なくとも一つの重合性官能基を有する。重合性官能基を一つ有する重合性モノマーは単官能モノマーとも称する。また、重合性官能基を二つ以上有する重合性モノマーは多官能モノマーとも称する。重合性モノマーの種類としては特に限定されないが、例えば、（メタ）アクリル系モノマー、ビニル系モノマーなどが挙げられる。また、エポキシ基やオキセタン構造などの環状エーテル構造を有する重合性モノマー（例えばε－カプロラクトン等）を用いることも可能である。
　なお、「（メタ）アクリレート」の表記は、「アクリレート」と「メタクリレート」との両方を含むことを意味する。 Regarding (A) above, the polymerizable monomer has at least one polymerizable functional group. A polymerizable monomer having one polymerizable functional group is also called a monofunctional monomer. A polymerizable monomer having two or more polymerizable functional groups is also called a polyfunctional monomer. Although the type of the polymerizable monomer is not particularly limited, examples thereof include (meth)acrylic monomers and vinyl monomers. A polymerizable monomer having a cyclic ether structure such as an epoxy group or an oxetane structure (eg, ε-caprolactone, etc.) can also be used.
Note that the notation of "(meth)acrylate" includes both "acrylate" and "methacrylate".
　単官能の（メタ）アクリル系モノマーとしては、例えば、２－ヒドロキシエチル（メタ）アクリレート、２－ヒドロキシプロピル（メタ）アクリレート、２－ヒドロキシブチル（メタ）アクリレート、ｎ－ブチル（メタ）アクリレート、イソブチル（メタ）アクリレート、ｔ－ブチル（メタ）アクリレート、グリシジル（メタ）アクリレート、アクリロイルモルフォリン、Ｎ－ビニルピロリドン、テトラヒドロフルフリールアクリレート、シクロヘキシル（メタ）アクリレート、２－エチルヘキシル（メタ）アクリレート、イソボルニル（メタ）アクリレート、イソデシル（メタ）アクリレート、ラウリル（メタ）アクリレート、トリデシル（メタ）アクリレート、セチル（メタ）アクリレート、ステアリル（メタ）アクリレート、ベンジル（メタ）アクリレート、２－エトキシエチル（メタ）アクリレート、３－メトキシブチル（メタ）アクリレート、エチルカルビトール（メタ）アクリレート、リン酸（メタ）アクリレート、エチレンオキサイド変性リン酸（メタ）アクリレート、フェノキシ（メタ）アクリレート、エチレンオキサイド変性フェノキシ（メタ）アクリレート、プロピレンオキサイド変性フェノキシ（メタ）アクリレート、ノニルフェノール（メタ）アクリレート、エチレンオキサイド変性ノニルフェノール（メタ）アクリレート、プロピレンオキサイド変性ノニルフェノール（メタ）アクリレート、メトキシジエチレングリコール（メタ）アクリレート、メトキシポリチレングリコール（メタ）アクリレート、メトキシプロピレングリコール（メタ）アクリレート、２－（メタ）アクリロイルオキシエチル－２－ヒドロキシプロピルフタレート、２－ヒドロキシ－３－フェノキシプロピル（メタ）アクリレート、２－（メタ）アクリロイルオキシエチルハイドロゲンフタレート、２－（メタ）アクリロイルオキシプロピルハイドロゲンフタレート、２－（メタ）アクリロイルオキシプロピルヘキサヒドロハイドロゲンフタレート、２－（メタ）アクリロイルオキシプロピルテトラヒドロハイドロゲンフタレート、ジメチルアミノエチル（メタ）アクリレート、トリフルオロエチル（メタ）アクリレート、テトラフルオロプロピル（メタ）アクリレート、ヘキサフルオロプロピル（メタ）アクリレート、オクタフルオロプロピル（メタ）アクリレート、２－アダマンタンおよびアダマンタンジオールから誘導される１価のモノ（メタ）アクリレートを有するアダマンチルアクリレートなどのアダマンタン誘導体モノ（メタ）アクリレート等が挙げられる。 Examples of monofunctional (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl ( meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3 - methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phosphoric acid (meth)acrylate, ethylene oxide-modified phosphoric acid (meth)acrylate, phenoxy (meth)acrylate, ethylene oxide-modified phenoxy (meth)acrylate, propylene oxide Modified phenoxy (meth)acrylate, nonylphenol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, propylene oxide-modified nonylphenol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (Meth) acrylate, 2-(meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-(meth) acryloyloxyethyl hydrogen phthalate, 2-(meth) acryloyl Oxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl ( meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, 2-adamantane and adamantanediol adamantane derivative mono(meth)acrylates such as adamantyl acrylate having a monovalent mono(meth)acrylate derived from
　２官能の（メタ）アクリル系モノマーとしては、例えば、エチレングリコールジ（メタ）アクリレート、ジエチレングリコールジ（メタ）アクリレート、ブタンジオールジ（メタ）アクリレート、ヘキサンジオールジ（メタ）アクリレート、ノナンジオールジ（メタ）アクリレート、エトキシ化ヘキサンジオールジ（メタ）アクリレート、プロポキシ化ヘキサンジオールジ（メタ）アクリレート、ジエチレングリコールジ（メタ）アクリレート、ポリエチレングリコールジ（メタ）アクリレート、トリプロピレングリコールジ（メタ）アクリレート、ポリプロピレングリコールジ（メタ）アクリレート、ネオペンチルグリコ－ルジ（メタ）アクリレート、エトキシ化ネオペンチルグリコールジ（メタ）アクリレート、トリプロピレングリコールジ（メタ）アクリレート、ヒドロキシピバリン酸ネオペンチルグリコールジ（メタ）アクリレートなどのジ（メタ）アクリレート等が挙げられる。 Examples of bifunctional (meth)acrylic monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate. ) acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate) Di(meth)acrylates such as (meth)acrylates, neopentyl glycol di(meth)acrylates, ethoxylated neopentyl glycol di(meth)acrylates, tripropylene glycol di(meth)acrylates, and neopentyl glycol hydroxypivalate di(meth)acrylates meth)acrylate and the like.
　３官能以上の（メタ）アクリル系モノマーとしては、例えば、トリメチロールプロパントリ（メタ）アクリレート、エトキシ化トリメチロールプロパントリ（メタ）アクリレート、プロポキシ化トリメチロールプロパントリ（メタ）アクリレート、トリス２－ヒドロキシエチルイソシアヌレートトリ（メタ）アクリレート、グリセリントリ（メタ）アクリレート等のトリ（メタ）アクリレート、ペンタエリスリトールトリ（メタ）アクリレート、ジペンタエリスリトールトリ（メタ）アクリレート、ジトリメチロールプロパントリ（メタ）アクリレート等の３官能の（メタ）アクリレート化合物や、ペンタエリスリトールテトラ（メタ）アクリレート、ジトリメチロールプロパンテトラ（メタ）アクリレート、ジペンタエリスリトールテトラ（メタ）アクリレート、ジペンタエリスリトールペンタ（メタ）アクリレート、ジトリメチロールプロパンペンタ（メタ）アクリレート、ジペンタエリスリトールヘキサ（メタ）アクリレート、ジトリメチロールプロパンヘキサ（メタ）アクリレート等の３官能以上の多官能（メタ）アクリレート化合物や、これら（メタ）アクリレートの一部をアルキル基やε－カプロラクトンで置換した多官能（メタ）アクリレート化合物等が挙げられる。 Examples of trifunctional or higher (meth)acrylic monomers include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-2-hydroxy Ethyl isocyanurate tri(meth)acrylate, tri(meth)acrylate such as glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, etc. Trifunctional (meth)acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta ( Trifunctional or higher polyfunctional (meth)acrylate compounds such as meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane hexa(meth)acrylate, and some of these (meth)acrylates are alkyl groups or ε- Polyfunctional (meth)acrylate compounds substituted with caprolactone, and the like.
　単官能のビニル系モノマーとしては例えば、ビニルエーテル系、ビニルエステル系、芳香族ビニル系、特にスチレンおよびスチレン系モノマーなど、常温で水と相溶しない液体が好ましい。
　単官能ビニル系モノマーのうち（メタ）アクリレートとしては、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、ｔ－ブチル（メタ）アクリレート、２－エチルヘキシル（メタ）アクリレート、ラウリル（メタ）アクリレート、アルキル（メタ）アクリレート、トリデシル（メタ）アクリレート、ステアリル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、ベンジル（メタ）アクリレート、イソボルニル（メタ）アクリレート、グリシジル（メタ）アクリレート、テトラヒドロフルフリル（メタ）アクリレート、アリル（メタ）アクリレート、ジエチルアミノエチル（メタ）アクリレート、トリフルオロエチル（メタ）アクリレート、ヘプタフルオロデシル（メタ）アクリレート、ジシクロペンテニル（メタ）アクリレート、ジシクロペンテニルオキシエチル（メタ）アクリレート、トリシクロデカニル（メタ）アクリレートなどが挙げられる。
　また、単官能芳香族ビニル系モノマーとしては、スチレン、α－メチルスチレン、ｏ－メチルスチレン、ｍ－メチルスチレン、ｐ－メチルスチレン、エチルスチレン、イソプロペニルトルエン、イソブチルトルエン、ｔｅｒｔ－ブチルスチレン、ビニルナフタレン、ビニルビフェニル、１，１－ジフェニルエチレンなどが挙げられる。 As monofunctional vinyl-based monomers, liquids which are incompatible with water at room temperature, such as vinyl ether-based, vinyl ester-based, aromatic vinyl-based, particularly styrene and styrene-based monomers, are preferred.
Examples of (meth)acrylates among monofunctional vinyl-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl ( meth)acrylate, alkyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl ( meth)acrylate, allyl (meth)acrylate, diethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, heptafluorodecyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate , tricyclodecanyl (meth)acrylate and the like.
Further, the monofunctional aromatic vinyl monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, isopropenyltoluene, isobutyltoluene, tert-butylstyrene, vinyl naphthalene, vinylbiphenyl, 1,1-diphenylethylene, and the like.
　多官能のビニル系モノマーとしてはジビニルベンゼンなどの不飽和結合を有する多官能基が挙げられる。常温で水と相溶しない液体が好ましい。
　例えば多官能性ビニル系モノマーとしては、具体的には、（１）ジビニルベンゼン、１，２，４－トリビニルベンゼン、１，３，５－トリビニルベンゼン等のジビニル類、（２）エチレングリコールジメタクリレート、ジエチレングリコールジメタクリレート、トリエチレングリコールジメタクリレート、ポリエチレングリコールジメタクリレート、１，３－プロピレングリコールジメタクリレート、１，４－ブチレングリコールジメタクリレート、１，６－ヘキサメチレングリコールジメタクリレート、ネオペンチルグリコールジメタクリレート、ジプロピレングリコールジメタクリレート、ポリプロピレングリコールジメタクリレート、２，２－ビス（４－メタクリロキシジエトキシフェニル）プロパン等のジメタクリレート類、（３）トリメチロールプロパントリメタクリレート、トリエチロールエタントリメタクリレート等のトリメタクリレート類、（４）エチレングリコールジアクリレート、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、ポリエチレングリコールジアクリレート、１，３－ジプロピレングリコールジアクリレート、１，４－ジブチレングリコールジアクリレート、１，６－ヘキシレングリコールジアクリレート、ネオペンチルグリコールジアクリレート、ジプロピレングリコールジアクリレート、ポリプロピレングリコールジアクリレート、２，２－ビス（４－アクリロキシプロポキシフェニル）プロパン、２，２－ビス（４－アクリロキシジエトキシフェニル）プロパン等のジアクリレート類、（５）トリメチロールプロパントリアクリレート、トリエチロールエタントリアクリレート等のトリアクリレート類、（６）テトラメチロールメタンテトラアクリレート等のテトラアクリレート類、（７）その他に、例えばテトラメチレンビス（エチルフマレート）、ヘキサメチレンビス（アクリルアミド）、トリアリルシアヌレート、トリアリルイソシアヌレートが挙げられる。
　例えば官能性スチレン系モノマーとしては、具体的には、ジビニルベンゼン、トリビニルベンゼン、ジビニルトルエン、ジビニルナフタレン、ジビニルキシレン、ジビニルビフェニル、ビス（ビニルフェニル）メタン、ビス（ビニルフェニル）エタン、ビス（ビニルフェニル）プロパン、ビス（ビニルフェニル）ブタン等が挙げられる。 Polyfunctional vinyl-based monomers include polyfunctional groups having unsaturated bonds such as divinylbenzene. Liquids that are incompatible with water at room temperature are preferred.
For example, polyfunctional vinyl-based monomers specifically include (1) divinyls such as divinylbenzene, 1,2,4-trivinylbenzene and 1,3,5-trivinylbenzene, and (2) ethylene glycol. Dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexamethylene glycol dimethacrylate, neopentyl glycol dimethacrylate Dimethacrylates such as methacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis(4-methacryloxydiethoxyphenyl)propane, (3) trimethylolpropane trimethacrylate, triethylolethane trimethacrylate, etc. trimethacrylates, (4) ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-dipropylene glycol diacrylate, 1,4-dibutylene glycol diacrylate, 1,6 - hexylene glycol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, 2,2-bis(4-acryloxypropoxyphenyl)propane, 2,2-bis(4-acryloxydi (5) triacrylates such as trimethylolpropane triacrylate and triethylolethane triacrylate; (6) tetraacrylates such as tetramethylolmethane tetraacrylate; Examples include tetramethylenebis(ethyl fumarate), hexamethylenebis(acrylamide), triallyl cyanurate and triallyl isocyanurate.
Specific examples of functional styrene monomers include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis(vinylphenyl)methane, bis(vinylphenyl)ethane, bis(vinyl phenyl)propane, bis(vinylphenyl)butane, and the like.
　これらの他にも重合性の官能基を少なくとも１つ以上有するポリエーテル樹脂、ポリエステル樹脂、ポリウレタン樹脂、エポキシ樹脂、アルキッド樹脂、スピロアセタール樹脂、ポリブタジエン樹脂、ポリチオールポリエン樹脂等を使用することができ、特にその材料は限定されない。
　上述した各種重合性モノマーは、単独で用いてもよいし、２種類以上を組み合わせて用いてもよい。 In addition to these, polyether resins, polyester resins, polyurethane resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having at least one or more polymerizable functional groups can be used. The material is not particularly limited.
The various polymerizable monomers described above may be used alone, or two or more of them may be used in combination.
　上記（Ｂ）について、熱可塑性ポリマーとしては、融点が４０℃以上８０℃以下であることが好ましい。融点が４０℃より低いと、室温において固体として形状を維持することが困難となり、使用環境が極端に制限されるため好ましくない。一方、融点が８０℃を超えると、微細化セルロース分散液中において溶融状態を維持することが製造工程上困難となるため好ましくない。より好ましくは、融点が４５℃以上７５℃以下である。また、融点以上でのメルトフローレート（ＭＦＲ）が１０以上であることが好ましい。ＭＦＲが１０未満の場合、前述の乳化処理において多大な乳化エネルギーを要するため好ましくない。 Regarding (B) above, the thermoplastic polymer preferably has a melting point of 40°C or higher and 80°C or lower. If the melting point is lower than 40° C., it becomes difficult to maintain the shape as a solid at room temperature, which is not preferable because the usage environment is extremely restricted. On the other hand, if the melting point exceeds 80° C., it is difficult to maintain the molten state in the finely divided cellulose dispersion in terms of the production process, which is not preferred. More preferably, the melting point is 45°C or higher and 75°C or lower. Also, the melt flow rate (MFR) above the melting point is preferably 10 or more. If the MFR is less than 10, the emulsification treatment described above requires a large amount of emulsifying energy, which is not preferable.
　上記（Ｃ）について、非硬化性ポリマーとしては、水を除く溶剤に溶解し、液体状を有するものである。ここで、非硬化性ポリマーを溶解させる溶剤としては、２０℃における水溶解度が水１Ｌに対して２０g以上２０００g以下であることが好ましい。２０g未満である場合、溶剤を含む液滴と微細化セルロース１の親和性が低く、微細化セルロース１によるエマルション安定化効果が低下する。一方、２０００ｇより大きい場合、微細化セルロース分散液中での溶剤の拡散速度が早いために液滴が形状を維持できない。その結果、微細化セルロース１による液滴被覆効果が損なわれる。 Regarding (C) above, the non-curable polymer is one that dissolves in a solvent other than water and has a liquid state. Here, the solvent for dissolving the non-curable polymer preferably has a water solubility of 20 g or more and 2000 g or less per 1 L of water at 20°C. If it is less than 20 g, the affinity between the droplets containing the solvent and the micronized cellulose 1 is low, and the emulsion stabilizing effect of the micronized cellulose 1 is reduced. On the other hand, if it is more than 2000 g, the droplets cannot maintain their shape due to the high diffusion speed of the solvent in the finely divided cellulose dispersion. As a result, the droplet covering effect of the micronized cellulose 1 is impaired.
　熱可塑性ポリマーおよび非硬化性ポリマーは、本実施形態の機能が損なわれない限りにおいてその材料は限定されない。例えば、上述した各種単官能モノマーや、エポキシ基やオキセタン構造などの環状エーテル構造を有する重合性モノマーを出発物質とした重合体、あるいは、ポリエーテル樹脂、ポリエステル樹脂、ポリウレタン樹脂、エポキシ樹脂、アルキッド樹脂、スピロアセタール樹脂、ポリブタジエン樹脂、ポリチオールポリエン樹脂等を使用できる。 The thermoplastic polymer and the non-curable polymer are not limited as long as the functions of the present embodiment are not impaired. For example, the various monofunctional monomers described above, polymers starting from polymerizable monomers having a cyclic ether structure such as an epoxy group or an oxetane structure, or polyether resins, polyester resins, polyurethane resins, epoxy resins, and alkyd resins. , spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and the like can be used.
　熱可塑性ポリマーおよび非硬化性ポリマーとして、生分解性ポリマーを使用することもできる。生分解性ポリマーとしては、生分解性を有し、水に溶解しないものであれば特に制限はなく、具体的には、セルロースアセテート、セルロースアセテートブチレート、セルロースアセテートプロピオネート等のセルロースアセテート誘導体、キチン、キトサン等の多糖類、ポリ乳酸、乳酸と他のヒドロキシカルボン酸との共重合体等のポリ乳酸類；ポリブチレンサクシネート、ポリエチレンサクシネート、ポリブチレンアジペート等の二塩基酸ポリエステル類、ポリカプロラクトン、カプロラクトンとヒドロキシカルボン酸との共重合体等のポリカプロラクトン類、ポリヒドロキシブチレート、ポリヒドロキシブチレートとヒドロキシカルボン酸との共重合体等のポリヒドロキシブチレート類、ポリヒドロキシ酪酸、ポリヒドロキシ酪酸と他のヒドロキシカルボン酸との共重合体等の脂肪族ポリエステル類、ポリアミノ酸類、ポリエステルポリカーボネート類、ロジン等の天然樹脂等を例示できる。これらの化合物は単独で、または２種以上を併用して用いることができる。 Biodegradable polymers can also be used as thermoplastic polymers and non-curable polymers. The biodegradable polymer is not particularly limited as long as it is biodegradable and does not dissolve in water. Specifically, cellulose acetate derivatives such as cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. , polysaccharides such as chitin and chitosan; polylactic acids such as polylactic acid and copolymers of lactic acid and other hydroxycarboxylic acids; dibasic acid polyesters such as polybutylene succinate, polyethylene succinate and polybutylene adipate; Polycaprolactones such as polycaprolactone, copolymers of caprolactone and hydroxycarboxylic acid, polyhydroxybutyrates such as polyhydroxybutyrate, copolymers of polyhydroxybutyrate and hydroxycarboxylic acid, polyhydroxybutyric acid, poly Examples include aliphatic polyesters such as copolymers of hydroxybutyric acid and other hydroxycarboxylic acids, polyamino acids, polyester polycarbonates, and natural resins such as rosin. These compounds can be used alone or in combination of two or more.
　第三工程における微細化セルロース分散液（水相、連続相）とコア粒子前駆体２との重量比については特に限定されないが、１００質量部の微細化セルロース分散液に対し、コア粒子前駆体２が１質量部以上５０質量部以下であることが好ましい。コア粒子前駆体２が１質量部以下となると複合粒子５の収量が低下するため好ましくなく、５０質量部を超えると液滴６を微細化セルロース１で均一に被覆することが困難となり好ましくない。 The weight ratio of the micronized cellulose dispersion (aqueous phase, continuous phase) and the core particle precursor 2 in the third step is not particularly limited. is preferably 1 part by mass or more and 50 parts by mass or less. If the amount of the core particle precursor 2 is 1 part by mass or less, the yield of the composite particles 5 will decrease.
　コア粒子前駆体２として重合性モノマーを用いる場合は、予め重合開始剤が含まれていてもよい。一般的な重合開始剤として、有機過酸化物やアゾ重合開始剤などのラジカル開始剤等を例示できる。 When a polymerizable monomer is used as the core particle precursor 2, a polymerization initiator may be contained in advance. Examples of general polymerization initiators include radical initiators such as organic peroxides and azo polymerization initiators.
　有機過酸化物としては、パーオキシケタール、ハイドロパーオキサイド、ジアルキルパーオキサイド、ジアシルパーオキサイド、パーオキシカーボネート、パーオキシエステル等を例示できる。 Examples of organic peroxides include peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxycarbonates, and peroxyesters.
　アゾ重合開始剤としては、ＡＤＶＮ，ＡＩＢＮ等を例示できる。
　例えば２,２－アゾビス（イソブチロニトリル）（ＡＩＢＮ）、２,２－アゾビス（２－メチルブチロニトリル）（ＡＭＢＮ）、２,２－アゾビス（２,４－ジメチルバレロニトリル）（ＡＤＶＮ）、１,１－アゾビス（１－シクロヘキサンカルボニトリル）（ＡＣＨＮ）、ジメチル－２,２－アゾビスイソブチレート（ＭＡＩＢ）、４,４－アゾビス（４－シアノバレリアン酸）（ＡＣＶＡ）、１,１－アゾビス（１－アセトキシ－１－フェニルエタン）、２,２－アゾビス（２－メチルブチルアミド）、２,２－アゾビス（４－メトキシ－２,４－ジメチルバレロニトリル）、２,２－アゾビス（２－メチルアミジノプロパン）二塩酸塩、２,２－アゾビス［２－（２－イミダゾリン－２－イル）プロパン］、２,２－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）プロピオンアミド］、２,２－アゾビス（２,４,４－トリメチルペンタン）、２－シアノ－２－プロピルアゾホルムアミド、２,２－アゾビス（Ｎ－ブチル－２－メチルプロピオンアミド）、２,２－アゾビス（Ｎ－シクロヘキシル－２－メチルプロピオンアミド）等である。 ADVN, AIBN, etc. can be illustrated as an azo polymerization initiator.
For example 2,2-azobis(isobutyronitrile) (AIBN), 2,2-azobis(2-methylbutyronitrile) (AMBN), 2,2-azobis(2,4-dimethylvaleronitrile) (ADVN) , 1,1-azobis(1-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2-azobisisobutyrate (MAIB), 4,4-azobis(4-cyanovaleric acid) (ACVA), 1, 1-azobis(1-acetoxy-1-phenylethane), 2,2-azobis(2-methylbutyramide), 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2- Azobis(2-methylamidinopropane) dihydrochloride, 2,2-azobis[2-(2-imidazolin-2-yl)propane], 2,2-azobis[2-methyl-N-(2-hydroxyethyl) propionamide], 2,2-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2-azobis(N-butyl-2-methylpropionamide), 2,2 -azobis(N-cyclohexyl-2-methylpropionamide) and the like.
　第三工程において予め重合開始剤が含まれた状態の重合性モノマーを用いれば、Ｏ／Ｗ型エマルションを形成した際にエマルションの液滴中に重合開始剤が含まれるため、後述する第三工程においてエマルションの液滴内部のモノマーを重合させる重合反応が進行しやすくなる。 If a polymerizable monomer containing a polymerization initiator in advance is used in the third step, the droplets of the emulsion contain the polymerization initiator when the O/W emulsion is formed. The polymerization reaction for polymerizing the monomer inside the droplets of the emulsion proceeds more easily.
　第三工程における重合性モノマーと重合開始剤との重量比については特に限定されないが、通常、重合性モノマー１００質量部に対し、重合開始剤が０．１質量部以上であることが好ましい。重合開始剤が０．１質量部未満となると重合反応が充分に進行せずに複合粒子５の収量が低下するため好ましくない。 Although the weight ratio of the polymerizable monomer and the polymerization initiator in the third step is not particularly limited, it is usually preferable that the polymerization initiator is 0.1 parts by mass or more with respect to 100 parts by mass of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 parts by mass, the polymerization reaction does not proceed sufficiently, and the yield of the composite particles 5 decreases, which is not preferable.
　熱可塑性ポリマーを溶融させた溶融ポリマーを得る方法としては、例えば常温で固体のポリマーを溶融させて液体とする。溶融ポリマーを前述のように超音波ホモジナイザー等による機械処理を加えながら、第二工程で得られた微細化セルロース１の分散液を、ポリマーの溶融状態を維持可能な温度にまで加熱した状態で、溶融ポリマーを添加することによって、分散液中で溶融ポリマー液滴をＯ／Ｗ型エマルションとして安定化することが好ましい。 As a method of obtaining a molten polymer by melting a thermoplastic polymer, for example, a polymer that is solid at room temperature is melted to make it liquid. While the molten polymer is mechanically treated with an ultrasonic homogenizer or the like as described above, the dispersion of micronized cellulose 1 obtained in the second step is heated to a temperature at which the molten state of the polymer can be maintained. The addition of molten polymer preferably stabilizes the molten polymer droplets as an O/W emulsion in the dispersion.
　非硬化性ポリマーを溶解させて溶解ポリマーを調製するための溶媒は、特に限定されないが、エマルションを安定化させるためには、有機溶媒を用いることが好ましい。例えば、トルエン、キシレン、酢酸エチル、酢酸ブチル、メチルエチルケトン（ＭＥＫ）、メチルイソブチルケトン（ＭＩＢＫ）、イソホロン、セロソルブアセテート、イソホロン、ソルベッソ１００、トリクレン、ヘキサン、クロロホルム、ジクロロメタン、ジクロロエタン、イソオクタン、ノナン等を用いることができる。 The solvent for dissolving the non-curable polymer to prepare the dissolved polymer is not particularly limited, but it is preferable to use an organic solvent in order to stabilize the emulsion. For example, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), isophorone, cellosolve acetate, isophorone, Solvesso 100, trichlene, hexane, chloroform, dichloromethane, dichloroethane, isooctane, nonane, etc. are used. be able to.
　非硬化性ポリマーと溶媒の質量比は、特に限定されない。好ましくは、非硬化性ポリマーを１００質量部に対し、溶媒の質量は０．００５質量部以上９００質量部以下であることが好ましく、より好ましくは０．１質量部以上４００質量部以下であることが好ましい。 The mass ratio of the non-curable polymer and solvent is not particularly limited. Preferably, the weight of the solvent is preferably 0.005 parts by mass or more and 900 parts by mass or less, more preferably 0.1 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the non-curable polymer. is preferred.
　また、コア粒子前駆体２を含有する液体状の油相（分散相）には予め重合開始剤以外の他の機能性成分が含まれていてもよい。具体例として、溶媒、磁性体、医薬品、農薬、香料、接着剤、酵素、顔料、染料、消臭剤、金属、金属酸化物、無機酸化物、等を例示できる。重合性モノマーに予め重合開始剤以外の他の機能性成分が含まれている場合、製造された複合粒子５のコア粒子内部に機能性成分を含有させることができ、用途に応じた機能発現が可能となる。 Further, the liquid oil phase (dispersed phase) containing the core particle precursor 2 may contain functional components other than the polymerization initiator in advance. Specific examples include solvents, magnetic substances, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, dyes, deodorants, metals, metal oxides, inorganic oxides, and the like. When the polymerizable monomer contains in advance other functional components other than the polymerization initiator, the functional component can be contained inside the core particle of the manufactured composite particles 5, and the function can be expressed according to the application. It becomes possible.
（第四工程）
　第四工程は、図２に示すように、コア粒子前駆体２を固体化させることにより、液滴６を固体化させ、コア粒子３が被覆層１０で被覆された複合粒子５を得る工程である。 (Fourth step)
The fourth step, as shown in FIG. 2, is a step of solidifying the core particle precursor 2 to solidify the droplets 6 to obtain the composite particles 5 in which the core particles 3 are coated with the coating layer 10. be.
　コア粒子前駆体２を固体化する具体的方法は、コア粒子前駆体２の材質に応じて変化するため、コア粒子前駆体２を固体化させる方法については特に限定されない。コア粒子前駆体２として重合性を有する化合物を用いた場合、加熱や紫外線照射等にて重合することにより固体化できる。コア粒子前駆体２として溶融ポリマーを用いた場合、溶融ポリマーを冷却して凝固させて固体化させることができる。コア粒子前駆体２として溶解ポリマーを用いた場合、液滴６内部の溶媒を分散溶媒４に拡散させる方法や、溶媒を蒸発させる方法により溶媒を除去し、ポリマーを固体化できる。 Since the specific method for solidifying the core particle precursor 2 varies depending on the material of the core particle precursor 2, the method for solidifying the core particle precursor 2 is not particularly limited. When a compound having polymerizability is used as the core particle precursor 2, it can be solidified by polymerizing by heating, ultraviolet irradiation, or the like. When a molten polymer is used as the core particle precursor 2, the molten polymer can be cooled and solidified. When a dissolved polymer is used as the core particle precursor 2, the polymer can be solidified by removing the solvent by a method of diffusing the solvent inside the droplets 6 into the dispersion solvent 4 or a method of evaporating the solvent.
　重合性モノマーを用いる場合、重合する方法については特に限定されず、用いた重合性モノマーの種類および重合開始剤の種類によって適宜決定できる。重合法の一例として懸濁重合法が挙げられる。
　具体的な懸濁重合の方法についても特に限定されず、公知の方法を用いて実施することができる。例えば、第三工程で得られたＯ／Ｗ型エマルションを攪拌しながら加熱することにより、コア粒子前駆体２を固体化できる。攪拌の方法も特に限定されず、公知の方法を用いることができ、具体的にはディスパーや攪拌子を用いることができる。
　攪拌せずに加熱処理のみで固体化できる場合もある。加熱時の温度条件については重合性モノマーの種類および重合開始剤の種類によって適宜決定でき、例えば２０℃以上１５０℃以下でもよい。２０℃未満であると重合の反応速度が低下する場合があり、１５０℃を超えると微細化セルロース１が変性する場合がある。
　重合反応に供する時間は重合性モノマーの種類および重合開始剤の種類によって適宜でき、例えば１時間～２４時間程度でもよい。
　重合反応は、電磁波の一種である紫外線照射処理によって実施してもよい。また、電磁波以外にも電子線などの粒子線を用いてもよい。 When a polymerizable monomer is used, the polymerization method is not particularly limited, and can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator used. An example of the polymerization method is a suspension polymerization method.
A specific suspension polymerization method is also not particularly limited, and a known method can be used. For example, the core particle precursor 2 can be solidified by heating the O/W emulsion obtained in the third step while stirring. The stirring method is also not particularly limited, and a known method can be used. Specifically, a disper or a stirrer can be used.
In some cases, it can be solidified only by heat treatment without stirring. The temperature conditions during heating can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator, and may be, for example, 20° C. or higher and 150° C. or lower. If the temperature is less than 20°C, the polymerization reaction rate may decrease, and if it exceeds 150°C, the micronized cellulose 1 may be denatured.
The time for the polymerization reaction can be appropriately determined depending on the type of polymerizable monomer and the type of polymerization initiator, and may be, for example, about 1 hour to 24 hours.
The polymerization reaction may be carried out by ultraviolet irradiation treatment, which is a type of electromagnetic waves. In addition to electromagnetic waves, particle beams such as electron beams may be used.
　熱可塑性ポリマーを用いる場合、溶融ポリマーを相転移させることにより固体化させる。相転移の方法としては、冷却が典型的である。このとき、冷却速度を制御することにより熱可塑性ポリマーの結晶化度を制御することができる。冷却の具体的方法として、水あるいは氷水に拡散させる方法や、液体窒素等の冷媒に接触させる方法、放冷する方法等を例示できる。 When using a thermoplastic polymer, it is solidified by phase transition of the molten polymer. Cooling is the typical method of phase transition. At this time, the degree of crystallinity of the thermoplastic polymer can be controlled by controlling the cooling rate. Specific cooling methods include a method of diffusing in water or ice water, a method of contacting with a coolant such as liquid nitrogen, and a method of standing to cool.
　非硬化性ポリマーを用いる場合、溶解ポリマーから溶媒を除去することにより固体化させる。溶媒を除去する方法としては特に限定されず、加熱する方法や減圧する方法、電磁波を照射する方法、およびこれらの組み合わせを例示できる。 When using a non-curable polymer, it is solidified by removing the solvent from the dissolved polymer. A method for removing the solvent is not particularly limited, and examples thereof include a heating method, a pressure reduction method, an electromagnetic wave irradiation method, and a combination thereof.
　溶解ポリマーの溶媒を蒸発させる方法としては、具体的には、加熱又は／及び減圧乾燥により溶媒を蒸発させ、除去する。前記溶媒の沸点が水より低いと、溶媒を選択的に除去することが可能である。特に限定されないが、減圧条件下で加熱することにより効率的に溶媒を除去することができる。加熱温度は２０℃以上１００℃以下であることが好ましく、圧力は６００ｍＨｇ以上７５０ｍｍＨｇ以下であることが好ましい。 Specifically, the method for evaporating the solvent of the dissolved polymer is to evaporate and remove the solvent by heating and/or drying under reduced pressure. When the boiling point of the solvent is lower than that of water, it is possible to selectively remove the solvent. Although not particularly limited, the solvent can be efficiently removed by heating under reduced pressure conditions. The heating temperature is preferably 20° C. or higher and 100° C. or lower, and the pressure is preferably 600 mHg or higher and 750 mmHg or lower.
　溶解ポリマーの溶媒を分散溶媒４に拡散させる方法は、具体的には前記Ｏ／Ｗ型エマルション液に更に他の溶媒や塩を添加することにより液滴６内部の溶媒を分散溶媒４に拡散させる。分散溶媒４への溶解性の低い溶媒が経時的に分散溶媒４の水相へと拡散して行くことで、溶解ポリマーが析出して粒子として固体化させることができる。 The method of diffusing the solvent of the dissolved polymer into the dispersion solvent 4 is, specifically, to diffuse the solvent inside the droplets 6 into the dispersion solvent 4 by adding another solvent or salt to the O/W emulsion liquid. . As the solvent with low solubility in the dispersion solvent 4 diffuses into the aqueous phase of the dispersion solvent 4 over time, the dissolved polymer can be precipitated and solidified as particles.
　第四工程が終了すると、ポリマーを含むコア粒子３が微細化セルロース１によって被覆された略真球状の複合粒子５が得られる。得られた直後の複合粒子５においては、表在する微細化セルロース１の少なくとも一部に有機オニウムカチオン／アンモニウムイオン７ａが結合している。また、複合粒子５の粒径は比較的揃っており、均一度が高い。 When the fourth step is completed, substantially spherical composite particles 5 in which the polymer-containing core particles 3 are coated with the micronized cellulose 1 are obtained. In the composite particles 5 immediately after being obtained, organic onium cations/ammonium ions 7a are bound to at least part of the micronized cellulose 1 existing on the surface. In addition, the particle size of the composite particles 5 is relatively uniform, and the degree of uniformity is high.
　第四工程終了後間もない分散液は、複合粒子５と、多量の水と、コア粒子３と一体化せずに遊離している微細化セルロース１とが混在した状態となっている。
　この分散液から複合粒子５のみを取り出す際の回収・精製方法としては、遠心分離による洗浄や、ろ過洗浄等を例示できる。遠心分離による洗浄方法としては公知の方法を用いることができる。例えば、遠心分離で分散液中の複合粒子５を沈降させてから上澄みを除去し、水・メタノール混合溶媒に再分散する操作を繰り返し、最終的に遠心分離によって得られた沈降物から残留溶媒を除去することで複合粒子５を回収できる。ろ過洗浄についても公知の方法を用いることができる。例えば、孔径０．１μｍのポリテトラフルオロエチレン（ＰＴＦＥ）メンブレンフィルターを用いて水とメタノールで吸引ろ過を繰り返し、最終的にメンブレンフィルター上に残留したペーストから残留溶媒を除去することで複合粒子５を回収できる。
　いずれの場合も、残留溶媒の除去方法は特に限定されず、風乾やオーブンで熱乾燥にて実施することが可能である。複合粒子５を含む乾燥固形物は膜状や凝集体状にはならず、きめ細やかな粉体として得られる。
　なお、複合粒子５ではコア粒子３と微細化セルロース１とは不可分に結合しており、複合粒子５のみを取り出す回収・精製後であっても、微細化セルロース１とコア粒子３とが分離せず、微細化セルロース１によるコア粒子３の被覆状態が保たれる。 Immediately after the fourth step is completed, the dispersion liquid is in a state in which the composite particles 5, a large amount of water, and the finely divided cellulose 1 that is not integrated with the core particles 3 and are free are mixed.
Examples of the recovery/purification method for extracting only the composite particles 5 from the dispersion liquid include washing by centrifugation and washing by filtration. A known method can be used as a washing method by centrifugation. For example, the composite particles 5 in the dispersion are sedimented by centrifugation, the supernatant is removed, and the operation of redispersing in a mixed solvent of water and methanol is repeated, and the residual solvent is finally removed from the sediment obtained by centrifugation. Composite particles 5 can be recovered by removing them. A known method can also be used for filtration and washing. For example, suction filtration is repeated with water and methanol using a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.1 μm, and finally the composite particles 5 are obtained by removing the residual solvent from the paste remaining on the membrane filter. can be recovered.
In any case, the method for removing the residual solvent is not particularly limited, and it can be carried out by air drying or heat drying in an oven. The dry solid matter containing the composite particles 5 does not form a film or an aggregate, but is obtained as a fine powder.
In the composite particles 5, the core particles 3 and the micronized cellulose 1 are inseparably bonded, and even after recovery and purification of only the composite particles 5, the micronized cellulose 1 and the core particles 3 cannot be separated. Therefore, the state of covering the core particles 3 with the micronized cellulose 1 is maintained.
　上記工程により得られた複合粒子５の収率は、３０％以上であることが好ましく、より好ましくは５０％以上、更に好ましくは６０％以上である。有機オニウムイオン／アンモニウムイオン７ａを結合した微細化セルロース１を用いることで、安定したエマルションを得ることができ、高い収率で複合粒子５を安定的に作製することができる。
　収率は、複合粒子５の乾燥固形物の重量(ｇ)／製造に用いたコア粒子前駆体２の樹脂重量(ｇ)×１００として算出することができる。 The yield of the composite particles 5 obtained by the above steps is preferably 30% or more, more preferably 50% or more, still more preferably 60% or more. By using the micronized cellulose 1 to which the organic onium ion/ammonium ion 7a is bound, a stable emulsion can be obtained, and the composite particles 5 can be stably produced at a high yield.
The yield can be calculated as follows: Weight (g) of dry solid matter of composite particles 5/weight (g) of resin of core particle precursor 2 used for production×100.
（第五工程）
　第五工程は、得られた複合粒子５から有機オニウムカチオン／アンモニウムイオン７ａを取り除く工程である。第五工程は、必要に応じて第四工程の後に行われるものであり、複合粒子５の用途等に鑑みて不要であれば省略されてもよい。 (Fifth step)
The fifth step is to remove the organic onium cation/ammonium ion 7a from the composite particles 5 obtained. The fifth step is performed after the fourth step as necessary, and may be omitted if unnecessary in view of the use of the composite particles 5 and the like.
　上述したように、製造直後の複合粒子５においては、微細化セルロース１の一部が対イオンとして有機オニウムカチオン／アンモニウムイオン７ａを有する。複合粒子５の用途等に関連して、有機オニウムカチオン／アンモニウムイオン７ａの存在が好ましくない場合や、有機オニウムカチオン／アンモニウムイオン７ａとは異なるカチオン性物質をイオン結合として微細化セルロース１に結合したい場合、第五工程を行って有機オニウムカチオン／アンモニウムイオン７ａを除去してもよい。 As described above, in the composite particles 5 immediately after production, part of the micronized cellulose 1 has organic onium cations/ammonium ions 7a as counterions. When the presence of the organic onium cation/ammonium ion 7a is not preferable in relation to the use of the composite particles 5, or when a cationic substance different from the organic onium cation/ammonium ion 7a is desired to be bound to the micronized cellulose 1 as an ionic bond. In that case, a fifth step may be performed to remove the organic onium cation/ammonium ion 7a.
　有機オニウムカチオン／アンモニウムイオン７ａを取り除く方法としては、イオン交換が挙げられる。酸性化合物を含む水溶液中に有機オニウムカチオン／アンモニウムイオン７ａを有する複合粒子５を分散させ、さらに純水で洗浄することで有機オニウムカチオン／アンモニウムイオン７ａを除去できる。有機オニウムカチオン／アンモニウムイオン７ａを除去した後に所望のカチオン性化合物を添加し、微細化セルロース１のアニオン性官能基に有機オニウムカチオン／アンモニウムイオン７ａと異なるカチオン性物質をイオン結合により結合させても構わない。 Ion exchange is mentioned as a method for removing the organic onium cation/ammonium ion 7a. The organic onium cations/ammonium ions 7a can be removed by dispersing the composite particles 5 having the organic onium cations/ammonium ions 7a in an aqueous solution containing an acidic compound and then washing with pure water. After removing the organic onium cations/ammonium ions 7a, a desired cationic compound may be added to bond a cationic substance different from the organic onium cations/ammonium ions 7a to the anionic functional groups of the micronized cellulose 1 by ionic bonding. I do not care.
　以上説明したように、本実施形態に係る複合粒子５は、表面に被覆層１０として存在する微細化セルロース１を有する。また、複合粒子５は微細化セルロース１に由来した、高い生体親和性と、良好な分散安定性を有する。 As described above, the composite particles 5 according to this embodiment have the micronized cellulose 1 present as the coating layer 10 on the surface. Moreover, the composite particles 5 have high biocompatibility and good dispersion stability derived from the micronized cellulose 1 .
　また、有機オニウムカチオン／アンモニウムイオン７ａが結合した微細化セルロース１を用いて形成されるため、広範な種類の樹脂でコア粒子３を形成でき、多種多様な用途に対応可能な複合粒子を簡便な方法で得られる。例えば、従来製造が困難であった熱可塑性を有する複合粒子も簡便に製造できる。 Further, since the micronized cellulose 1 to which organic onium cations/ammonium ions 7a are bound is used, the core particles 3 can be formed from a wide variety of resins, and composite particles that can be used in a wide variety of applications can be easily produced. obtained by the method. For example, thermoplastic composite particles, which have been difficult to produce in the past, can be easily produced.
　さらに、有機オニウムカチオン／アンモニウムイオン７ａにより微細化セルロース１が疎水性を獲得することで、両親媒性となる。その結果、複合粒子５の収率が著しく向上するとともに、粒径分布も均一化し、材料としても優れたものとなる。 Furthermore, the micronized cellulose 1 acquires hydrophobicity due to the organic onium cations/ammonium ions 7a, thereby becoming amphiphilic. As a result, the yield of the composite particles 5 is remarkably improved, the particle size distribution is made uniform, and the material is excellent.
　複合粒子５の乾燥固形物は、微細化セルロース１の材料特性を発揮するものでありながら、きめ細やかな粉体として得られ、粒子同士の凝集がないため、再び溶媒に分散することも容易である。微細化セルロース１とコア粒子３とは不可分に結合しているため、再分散後も微細化セルロース１の特性に由来した安定した分散を示す。 The dry solid of the composite particles 5 exhibits the material properties of the micronized cellulose 1, but is obtained as a fine powder, and since there is no agglomeration of the particles, it can be easily dispersed again in a solvent. be. Since the micronized cellulose 1 and the core particles 3 are inseparably bonded, stable dispersion derived from the characteristics of the micronized cellulose 1 is exhibited even after redispersion.
　本実施形態に係る複合粒子５の製造方法は、微細化セルロース１の特性を発揮する粒子を、乾燥状態で流通可能な状態で簡便に取得できる。したがって、環境への負荷が低く、輸送費の削減、腐敗リスクの低減、添加剤としての添加効率の向上、疎水性樹脂への混練効率向上といった効果も期待できる。 The method for producing the composite particles 5 according to the present embodiment can easily obtain particles exhibiting the properties of the micronized cellulose 1 in a dry state and in a circulable state. Therefore, effects such as low environmental load, reduction in transportation costs, reduction in spoilage risk, improvement in addition efficiency as an additive, and improvement in kneading efficiency with hydrophobic resin can be expected.
　本発明の実施例について、実施例を用いてさらに説明する。本発明の技術的範囲は、実施例の具体的内容について何ら制限されない。
　以降の説明において、「％」は、特にことわりない限り、質量％を意味する。 Examples of the present invention will be further described using examples. The technical scope of the present invention is not limited by the specific contents of the examples.
In the following description, "%" means % by mass unless otherwise specified.
＜実施例１＞
（第一工程：微細化セルロース分散液を得る工程）
（木材セルロースのＴＥＭＰＯ酸化）
　針葉樹クラフトパルプ７０ｇを蒸留水３５００ｇに懸濁し、蒸留水３５０ｇにＴＥＭＰＯを０．７ｇ、臭化ナトリウムを７ｇ溶解させた溶液を加え、２０℃まで冷却した。ここに２ｍｏｌ／Ｌ、密度１．１５ｇ／ｍＬの次亜塩素酸ナトリウム水溶液４５０ｇを滴下により添加し、酸化反応を開始した。系内の温度は常に２０℃に保ち、反応中のｐＨの低下は０．５Ｎの水酸化ナトリウム水溶液を添加することでｐＨ１０に保ち続けた。セルロースの質量に対して、水酸化ナトリウムの添加量の合計が３．０ｍｍｏｌ／ｇに達した時点で、約１００ｍＬのエタノールを添加し反応を停止させた。その後、ガラスフィルターを用いて蒸留水によるろ過洗浄を繰り返し、ＴＥＭＰＯ酸化セルロース（酸化セルロース、酸化パルプ）を得た。 <Example 1>
(First step: step of obtaining a micronized cellulose dispersion)
(TEMPO oxidation of wood cellulose)
70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution prepared by dissolving 0.7 g of TEMPO and 7 g of sodium bromide in 350 g of distilled water was added and cooled to 20°C. 450 g of an aqueous sodium hypochlorite solution having a density of 1.15 g/mL and 2 mol/L was added dropwise to initiate an oxidation reaction. The temperature in the system was always kept at 20° C., and the decrease in pH during the reaction was kept at pH 10 by adding a 0.5N sodium hydroxide aqueous solution. When the total added amount of sodium hydroxide reached 3.0 mmol/g with respect to the mass of cellulose, about 100 mL of ethanol was added to terminate the reaction. Thereafter, filtration and washing with distilled water were repeated using a glass filter to obtain TEMPO oxidized cellulose (oxidized cellulose, oxidized pulp).
　（酸化セルロースのカルボキシ基量測定）
　例えば、上記ＴＥＭＰＯ酸化で得た酸化パルプを固形分質量で０．１ｇ量りとり、１％濃度で水に分散させ、塩酸を加えてｐＨを２．５とした。その後０．５Ｍ水酸化ナトリウム水溶液を用いた電導度滴定法により、カルボキシ基量（ｍｍｏｌ／ｇ）を求めてもよい。 (Measurement of carboxyl group content of oxidized cellulose)
For example, 0.1 g of solid content of the oxidized pulp obtained by the TEMPO oxidation was weighed out, dispersed in water at a concentration of 1%, and hydrochloric acid was added to adjust the pH to 2.5. After that, the amount of carboxyl groups (mmol/g) may be determined by conductivity titration using a 0.5 M sodium hydroxide aqueous solution.
　（酸化セルロースの解繊処理）
　上記ＴＥＭＰＯ酸化で得た酸化セルロース０．５ｇを９９．５ｇの蒸留水に分散させ、ジューサーミキサーで３０分間微細化処理し、濃度０．５％の微細化セルロース水分散液を得た。
（微細化セルロースの評価）
　得られた酸化セルロース、微細化セルロース（セルロースナノファイバー）について、カルボキシ基量、結晶化度、長軸の数平均軸径、光線透過率及びレオロジーの測定や算出を次のように行った。得られた微細化セルロースの評価結果を表１、図３、図４に示す。 (Fibrillation treatment of oxidized cellulose)
0.5 g of the oxidized cellulose obtained by the above TEMPO oxidation was dispersed in 99.5 g of distilled water, and subjected to a micronization treatment with a juicer mixer for 30 minutes to obtain a micronized cellulose aqueous dispersion having a concentration of 0.5%.
(Evaluation of micronized cellulose)
For the obtained oxidized cellulose and micronized cellulose (cellulose nanofiber), the amount of carboxyl groups, the crystallinity, the number-average axial diameter of the long axis, the light transmittance and the rheology were measured and calculated as follows. Table 1, FIG. 3, and FIG. 4 show the evaluation results of the obtained micronized cellulose.
（カルボキシ基量の測定）
　分散処理前の酸化セルロースについて、カルボキシ基量を以下の方法にて算出した。
　酸化セルロースの乾燥質量換算０．２ｇをビーカーに採り、イオン交換水８０ｍＬを添加した。 (Measurement of carboxy group content)
The carboxy group content of the oxidized cellulose before dispersion treatment was calculated by the following method.
0.2 g of oxidized cellulose in terms of dry mass was placed in a beaker, and 80 mL of ion-exchanged water was added.
　そこに、０．０１ｍｏｌ／Ｌ塩化ナトリウム水溶液５ｍＬを加え、攪拌しながら、０．１ｍｏｌ／Ｌ塩酸を加えて、全体がｐＨ２．８となるように調整した。
　また、自動滴定装置（商品名：ＡＵＴ－７０１、東亜ディーケーケー社製）を用いて、０．１ｍｏｌ／Ｌ水酸化ナトリウム水溶液を０．０５ｍＬ／３０秒で注入し、３０秒毎の電導度とｐＨ値を測定し、ｐＨ１１まで測定を続けた。 5 mL of a 0.01 mol/L sodium chloride aqueous solution was added thereto, and 0.1 mol/L hydrochloric acid was added while stirring to adjust the pH of the whole to 2.8.
In addition, using an automatic titrator (trade name: AUT-701, manufactured by Toa DKK Co., Ltd.), 0.1 mol / L sodium hydroxide aqueous solution was injected at 0.05 mL / 30 seconds, and the conductivity and pH were measured every 30 seconds. The value was measured and continued until pH 11.
　得られた電導度曲線から、水酸化ナトリウムの滴定量を求め、カルボキシ基の含有量を算出した。 From the obtained conductivity curve, the titration amount of sodium hydroxide was determined, and the content of carboxyl groups was calculated.
（結晶化度の算出）
　ＴＥＭＰＯ酸化セルロースの結晶化度を算出した。
　ＴＥＭＰＯ酸化セルロースについて、試料水平型多目的Ｘ線回折装置（商品名：ＵｌｔｉｍａＩＩＩ、Ｒｉｇａｋｕ社製）を用い、Ｘ線出力：（４０ｋｖ、４０ｍＡ）の条件で、５°≦２θ≦３５°の範囲でＸ線回折パターンを測定した。得られるＸ線回折パターンはセルロースＩ型結晶構造に由来するものであるため、下記の式（２）を用い、以下に示す手法により、ＴＥＭＰＯ酸化セルロースの結晶化度を算出した。 (Calculation of crystallinity)
The crystallinity of TEMPO-oxidized cellulose was calculated.
For TEMPO oxidized cellulose, using a sample horizontal multipurpose X-ray diffractometer (trade name: Ultima III, manufactured by Rigaku), X-ray output: (40 kv, 40 mA), X in the range of 5 ° ≤ 2θ ≤ 35 ° A line diffraction pattern was measured. Since the obtained X-ray diffraction pattern is derived from the cellulose type I crystal structure, the crystallinity of the TEMPO-oxidized cellulose was calculated using the following formula (2) by the method shown below.
　結晶化度（％）＝〔（Ｉ２２．６－Ｉ１８．５）／Ｉ２２．６〕×１００・・・（２） Crystallinity (%) = [(I22.6-I18.5)/I22.6] x 100 (2)
　ただし、Ｉ２２．６は、Ｘ線回折における格子面（００２面）（回折角２θ＝２２．６°）の回折強度、Ｉ１８．５は、アモルファス部（回折角２θ＝１８．５°）の回折強度を示す。 However, I22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6°) in X-ray diffraction, and I18.5 is the diffraction of the amorphous part (diffraction angle 2θ = 18.5°). Show strength.
　（微細化セルロースの短軸および長軸の数平均軸径の算出）
　原子間力顕微鏡を用いて、微細化セルロースの長軸の数平均軸径を算出した。 (Calculation of number-average axial diameters of short and long axes of micronized cellulose)
Using an atomic force microscope, the number average axial diameter of the long axis of the micronized cellulose was calculated.
　まず、微細化セルロース水分散液を０．００１％となるように希釈した後、マイカ板上に２０μＬずつキャストして風乾した。
　乾燥後に原子間力顕微鏡（商品名：ＡＦＭ５４００Ｌ、日立ハイテクノロジーズ社製）を用い、ＤＦＭモードで微細化セルロースの形状を観察した。 First, after diluting the micronized cellulose aqueous dispersion to 0.001%, 20 μL each was cast on a mica plate and air-dried.
After drying, the shape of the micronized cellulose was observed in DFM mode using an atomic force microscope (trade name: AFM5400L, manufactured by Hitachi High-Technologies Corporation).
　微細化セルロースの長軸の数平均軸径は、原子間力顕微鏡による観察画像から１００本の繊維の長軸径（最大径）を測定し、その平均値として求めた。同様に繊維の短軸径を測定することで、微細化セルロースの短軸の数平均軸径を算出した。 The number average axis diameter of the long axis of the micronized cellulose was obtained by measuring the long axis diameter (maximum diameter) of 100 fibers from an image observed with an atomic force microscope and calculating the average value. By similarly measuring the short axis diameter of the fiber, the number average axial diameter of the short axis of the micronized cellulose was calculated.
（微細化セルロース水分散液の光線透過率の測定）
　微細化セルロース０．５質量％の水分散液について、光線透過率を測定した。 (Measurement of light transmittance of micronized cellulose aqueous dispersion)
Light transmittance was measured for an aqueous dispersion containing 0.5% by mass of micronized cellulose.
　石英製のサンプルセルの一方にはリファレンスとして水を入れ、もう一方には気泡が混入しないように微細化セルロース水分散液を入れ、光路長１ｃｍにおける波長２２０ｎｍから８００ｎｍまでの光線透過率を分光光度計（商品名：ＮＲＳ－１０００、日本分光社製）にて測定した。測定結果を図３に示す。 One side of a quartz sample cell was filled with water as a reference, and the other side was filled with a micronized cellulose aqueous dispersion to prevent inclusion of air bubbles. (trade name: NRS-1000, manufactured by JASCO Corporation). The measurement results are shown in FIG.
（レオロジー測定）
　微細化セルロース０．５質量％の分散液のレオロジーをレオメーター（商品名：ＡＲ２０００ｅｘ、ティー・エイ・インスツルメント社製）を用い、傾斜角１°のコーンプレートにて測定した。 (Rheology measurement)
The rheology of a dispersion containing 0.5% by mass of micronized cellulose was measured using a rheometer (trade name: AR2000ex, manufactured by TA Instruments) with a cone plate having an inclination angle of 1°.
　測定部を２５℃に温調し、せん断速度を０．０１ｓ－１から１０００ｓ－１について連続的にせん断粘度を測定した。その結果を図４に示す。図４から明らかなように、微細化セルロース分散液はチキソトロピック性を示した。せん断速度が１０ｓ－１と１００ｓ－１のときのせん断粘度を表１に示す。 The temperature of the measurement part was adjusted to 25° C., and the shear viscosity was continuously measured at a shear rate of 0.01 s −1 to 1000 s −1 . The results are shown in FIG. As is clear from FIG. 4, the micronized cellulose dispersion exhibited thixotropic properties. Table 1 shows shear viscosities at shear rates of 10 s −1 and 100 s −1 .
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　図３から明らかなように、微細化セルロース水分散液は高い透明性を示した。また、微細化セルロース水分散液に含まれる微細化セルロース（ＴＥＭＰＯ酸化ＣＮＦ）の数平均短軸径は３ｎｍ、数平均長軸径は８３１ｎｍであった。更に、レオメーターを用いて定常粘弾性測定を行った結果を図４に示す。図４から明らかなように、微細化セルロース分散液はチキソトロピック性を示した。 As is clear from FIG. 3, the micronized cellulose aqueous dispersion exhibited high transparency. Further, the number average short axis diameter of the micronized cellulose (TEMPO-oxidized CNF) contained in the micronized cellulose aqueous dispersion was 3 nm, and the number average long axis diameter was 831 nm. Furthermore, FIG. 4 shows the results of steady-state viscoelasticity measurement using a rheometer. As is clear from FIG. 4, the micronized cellulose dispersion exhibited thixotropic properties.
（第二工程）
（対イオン置換による有機オニウムカチオン導入）
　前記微細化セルロース分散液をスターラーで攪拌しながら、有機オニウム化合物であるテトラブチルアンモニウムクロリド（ＴＢＡＣｌ）を微細化セルロースのカルボキシ基に対して１．０当量加えた。スターラーを用いて１時間撹拌し、対イオン置換により有機オニウムカチオンが導入されたイオン結合微細化セルロース分散液を得た。 (Second step)
(Introduction of organic onium cations by counterion substitution)
While stirring the micronized cellulose dispersion with a stirrer, 1.0 equivalent of tetrabutylammonium chloride (TBACl), which is an organic onium compound, was added to the carboxyl groups of the micronized cellulose. The mixture was stirred for 1 hour using a stirrer to obtain an ionically bonded finely divided cellulose dispersion into which organic onium cations were introduced by counterion substitution.
（第三工程）
（Ｏ／Ｗ型エマルションを作製する工程）
　コア粒子前駆体として、重合性モノマーである単官能性メタクリレート、イソボルニルメタクリレート（以下、「ＩＢ－Ｘ」とも称する。）１０ｇを用い、重合開始剤である２、２－アゾビス－２、４－ジメチルバレロニトリル（以下、「ＡＤＶＮ」とも称する。）を１ｇ溶解させた。ＩＢ－Ｘ／ＡＤＶＮ混合溶液全量を、濃度１％の微細化セルロース分散液４０ｇに対し添加した。ＩＢ－Ｘ／ＡＤＶＮ混合溶液と分散液とは、それぞれ透明性の高い状態で２相に分離した。 (Third step)
(Step of producing O/W type emulsion)
10 g of monofunctional methacrylate and isobornyl methacrylate (hereinafter also referred to as “IB-X”), which are polymerizable monomers, were used as the core particle precursor, and 2,2-azobis-2,4, which is a polymerization initiator, was used. - 1 g of dimethylvaleronitrile (hereinafter also referred to as "ADVN") was dissolved. The total amount of the IB-X/ADVN mixed solution was added to 40 g of micronized cellulose dispersion having a concentration of 1%. The IB-X/ADVN mixed solution and the dispersion separated into two phases with high transparency.
　次に、２相分離した状態の混合液における上相の液面から超音波ホモジナイザーのシャフトを挿入し、周波数２４ｋＨｚ、出力４００Ｗの条件で、超音波ホモジナイザー処理を３分間行った。超音波ホモジナイザー処理後の混合液は、白濁した乳化液の状態となった。混合液一滴をスライドグラスに滴下し、カバーガラスで封入して光学顕微鏡で観察したところ、数μｍ以下のＩＢ－Ｘのエマルション液滴が多数観察され、Ｏ／Ｗ型エマルションとして分散安定化している様子が確認された。 Next, the shaft of an ultrasonic homogenizer was inserted from the liquid surface of the upper phase in the liquid mixture in which the two phases were separated, and ultrasonic homogenizer treatment was performed for 3 minutes under the conditions of a frequency of 24 kHz and an output of 400 W. After being treated with an ultrasonic homogenizer, the mixture turned into a cloudy emulsion. When one drop of the mixed liquid was dropped on a slide glass, sealed with a cover glass, and observed with an optical microscope, a large number of IB-X emulsion droplets of several μm or less were observed, and the dispersion was stabilized as an O/W emulsion. The situation was confirmed.
　（第四工程）
（コア粒子前駆体の固体化により微細化セルロースで被覆された複合粒子を得る工程）
　Ｏ／Ｗ型エマルション分散液を、ウォーターバスを用いて７０℃の湯浴中に供し、攪拌子で攪拌しながら８時間処理し、重合反応を実施した。８時間処理後に上記分散液を室温まで冷却し、コア粒子前駆体を固体化して、分散液中に複合粒子を生成した。重合反応の前後で分散液の外観に変化はなかった。
　得られた分散液を遠心分離（７５０００ｇ、５分間）して複合粒子を含む沈降物を得た。デカンテーションにより上澄みを除去して沈降物を回収し、さらに孔径０．１μｍのＰＴＦＥメンブレンフィルターを用いて、純水とメタノールで繰り返し洗浄した。こうして精製・回収された複合粒子を１％濃度で純水に再分散させ、粒子形状画像解析装置（セイシン企業、ＰＩＴＡ－０４）を用いて粒径を測定したところ平均粒径（メジアン値）は１．３μｍであった。複合粒子を風乾し、室温２５度にて真空乾燥処理を２４時間実施したところ、きめ細やかな乾燥粉体となり、凝集や膜状化を生じなかった。 (Fourth step)
(Step of obtaining composite particles coated with micronized cellulose by solidifying core particle precursor)
The O/W emulsion dispersion was placed in a water bath at 70° C. and stirred for 8 hours with a stirrer to carry out a polymerization reaction. After the treatment for 8 hours, the above dispersion was cooled to room temperature to solidify the core particle precursor, thereby producing composite particles in the dispersion. There was no change in the appearance of the dispersion before and after the polymerization reaction.
The resulting dispersion was centrifuged (75000 g, 5 minutes) to obtain a sediment containing composite particles. The supernatant was removed by decantation to collect the sediment, which was then repeatedly washed with pure water and methanol using a PTFE membrane filter with a pore size of 0.1 μm. The composite particles thus purified and recovered were re-dispersed in pure water at a concentration of 1%, and the particle size was measured using a particle shape image analyzer (PITA-04, Seishin Enterprise Co., Ltd.). It was 1.3 μm. When the composite particles were air-dried and subjected to vacuum drying treatment at room temperature of 25°C for 24 hours, fine dry powder was obtained without agglomeration or film formation.
（ＳＥＭによる複合粒子の形状観察）
　上記乾燥粉体のＳＥＭ像を図５Ａおよび図５Ｂに示す。図５Ａは倍率２万倍、図５Ｂは倍率５万倍の像である。第三工程および第四工程において、Ｏ／Ｗ型エマルション液滴を鋳型として重合反応を実施したことにより、エマルション液滴の形状に由来した真球状の複合粒子５が多数得られ、粒径の均一度も高いことが図５Ａからわかる。
　図５Ｂに示されているように、粒子の表面を観察すると繊維状の凹凸が見られることから、複合粒子の表面は幅数ｎｍ程度の微細化セルロース１によってまんべんなく被覆されていることがわかる。図５Ｂには、繰り返しろ過洗浄した後の複合粒子の像が示されていることから、本実施例の複合粒子５において、コア粒子３と微細化セルロース１とは結合しており、不可分の状態にあることが示された。
（複合粒子の粒度分布）
　上記乾燥粉体の粒度分布をベックマン・コールター社製の粒度分布計ＬＳ－１３３２０により測定した結果を図８に示す。実施例１の粒度分布は平均粒径（メジアン値）が１．３μｍとして、粒径が１０μｍ以下の範囲にほぼ収まっており、ＳＥＭ像と良好な一致を示した。 (Shape observation of composite particles by SEM)
SEM images of the dry powder are shown in FIGS. 5A and 5B. FIG. 5A is an image at a magnification of 20,000 times, and FIG. 5B is an image at a magnification of 50,000 times. In the third step and the fourth step, the polymerization reaction was carried out using the O/W type emulsion droplet as a template, so that a large number of spherical composite particles 5 derived from the shape of the emulsion droplet were obtained, and the particle size was uniform. It can be seen from FIG. 5A that once higher.
As shown in FIG. 5B, when observing the surface of the particles, fibrous unevenness can be seen, so it can be seen that the surface of the composite particles is evenly coated with micronized cellulose 1 with a width of about several nm. FIG. 5B shows an image of the composite particles after repeated filtration and washing. Therefore, in the composite particles 5 of the present example, the core particles 3 and the micronized cellulose 1 are bonded and inseparable. was shown to be in
(Particle size distribution of composite particles)
FIG. 8 shows the results of measuring the particle size distribution of the dry powder with a particle size distribution analyzer LS-13320 manufactured by Beckman Coulter. The particle size distribution of Example 1, with an average particle size (median value) of 1.3 μm, was almost within the range of 10 μm or less, showing good agreement with the SEM image.
＜実施例２～８＞
　アルカリ種として有機オニウム化合物であるテトラブチルアンモニウムクロリド（ＴＢＡＣｌ）に代えて以下の有機オニウム化合物を使用した点を除き、実施例１と同様の手順で実施例２～８に係る複合粒子を作製した。
　実施例２　テトラブチルアンモニウムブロミド（ＴＢＡＢｒ）
　実施例３　テトラブチルアンモニウムヒドロキシド（ＴＢＡＨ）
　実施例４　テトラメチルアンモニウムヒドロキシド（ＴＭＡＨ）
　実施例５　アルキルベンジルジメチルアンモニウムクロリド（塩化ベンザルコニウム）
　実施例６　ジメチルステアリルアミン（ＤＭＳＡ）
　実施例７　ステアリルアミン
　実施例８　トリヘキシルアミン <Examples 2 to 8>
Composite particles according to Examples 2 to 8 were produced in the same manner as in Example 1, except that the following organic onium compounds were used in place of the organic onium compound tetrabutylammonium chloride (TBACl) as the alkaline species. .
Example 2 Tetrabutylammonium Bromide (TBABr)
Example 3 Tetrabutylammonium Hydroxide (TBAH)
Example 4 Tetramethylammonium Hydroxide (TMAH)
Example 5 Alkylbenzyldimethylammonium chloride (benzalkonium chloride)
Example 6 Dimethylstearylamine (DMSA)
Example 7 Stearylamine Example 8 Trihexylamine
＜実施例９～１２＞
　有機オニウム化合物であるテトラブチルアンモニウムヒドロキシド（ＴＢＡＨ）を微細化セルロースのカルボキシ基に対して下記の量添加した点を除き、実施例３と同様の手順で実施例９から実施例１２に係る複合粒子を作製した。
　実施例９　０．０１当量
　実施例１０　０．０５当量
　実施例１１　０．２５当量
　実施例１２　０．５０当量 <Examples 9 to 12>
Composites according to Examples 9 to 12 were prepared in the same manner as in Example 3, except that the following amount of tetrabutylammonium hydroxide (TBAH), an organic onium compound, was added to the carboxy groups of the micronized cellulose. Particles were produced.
Example 9 0.01 equivalents Example 10 0.05 equivalents Example 11 0.25 equivalents Example 12 0.50 equivalents
＜実施例１３～１５＞
　ＩＢ－Ｘに代えて、以下のモノマー・オリゴマーをコア粒子前駆体とした点を除き、実施例１と同様の手順で実施例１３から実施例１５に係る複合粒子を作製した。
　実施例１３　単官能性アクリレートであるイソボニルアクリレート（ＩＢ－ＸＡ）
　実施例１４　単官能性ビニルモノマーであるｐ－メチルスチレン（ｐ－ＭｅＳｔ）
　実施例１５　二官能性ウレタンアクリレートオリゴマー（ＵＡ４２００） <Examples 13 to 15>
Composite particles according to Examples 13 to 15 were produced in the same manner as in Example 1, except that the following monomers/oligomers were used as core particle precursors instead of IB-X.
Example 13 Monofunctional Acrylate Isobornyl Acrylate (IB-XA)
Example 14 Monofunctional Vinyl Monomer p-Methylstyrene (p-MeSt)
Example 15 Difunctional Urethane Acrylate Oligomer (UA4200)
＜実施例１６＞
　コア粒子前駆体として、ポリカプロラクトン（ＰＣＬ、分子量１０,０００）を使用した。第三工程において、ＰＣＬの２０％ＭＥＫ溶液を微細化セルロース分散液に添加した。この分散液を７５℃に加熱して超音波ホモジナイザー処理を行い、Ｏ／Ｗ型エマルションとした後、第四工程において、重合反応を行う代わりに、氷水で冷却して液滴を固体化した。
　それ以外は、実施例１と同様の条件で実施例１６に係る複合粒子を作製した。 <Example 16>
Polycaprolactone (PCL, molecular weight 10,000) was used as a core particle precursor. In a third step, a 20% MEK solution of PCL was added to the micronized cellulose dispersion. After heating this dispersion to 75° C. and subjecting it to an ultrasonic homogenizer treatment to form an O/W emulsion, in the fourth step, instead of performing a polymerization reaction, the droplets were solidified by cooling with ice water.
A composite particle according to Example 16 was produced under the same conditions as in Example 1 except for the above.
＜実施例１７＞
　ＴＥＭＰＯ酸化ＣＮＦに代えて、特許文献２に記載されたカルボキシメチル化（以下、「ＣＭ化」とも称する。）処理を行って得られたＣＭ化ＣＮＦを用いたこと以外は、実施例１と同様の条件で実施例１７に係る複合粒子を作製した。 <Example 17>
The same as in Example 1, except that instead of TEMPO-oxidized CNF, CM-CNF obtained by performing the carboxymethylation (hereinafter also referred to as "CM-conversion") treatment described in Patent Document 2 was used. Composite particles according to Example 17 were produced under the conditions.
＜実施例１８＞
　実施例１において、ＴＥＭＰＯ酸化の代わりに、先行技術文献として挙げた非特許文献１に従いリン酸エステル化処理を行って得られたリン酸エステル化ＣＮＦ分散液を用いたこと以外は、実施例１と同様の条件で実施例１８に係る複合粒子を作製した。 <Example 18>
In Example 1, instead of TEMPO oxidation, a phosphorylated CNF dispersion obtained by performing a phosphorylation treatment according to Non-Patent Document 1 cited as a prior art document was used. Composite particles according to Example 18 were produced under the same conditions as in .
＜比較例１＞
　ＴＥＭＰＯ酸化処理しない未処理パルプを用いた点を除き、実施例１と同様の手順で比較例１に係る粒子を作製した。 <Comparative Example 1>
Particles according to Comparative Example 1 were produced in the same manner as in Example 1, except that untreated pulp that was not TEMPO oxidized was used.
＜比較例２＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１と同様の手順で比較例１に係る粒子を作製した。 <Comparative Example 2>
Particles according to Comparative Example 1 were prepared in the same manner as in Example 1, except that TBACl was not added.
＜比較例３＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１３と同様の手順で比較例３に係る粒子を作製した。 <Comparative Example 3>
Particles according to Comparative Example 3 were produced in the same manner as in Example 13, except that TBACl was not added.
＜比較例４＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１４と同様の手順で比較例４に係る粒子を作製した。 <Comparative Example 4>
Particles according to Comparative Example 4 were prepared in the same manner as in Example 14, except that TBACl was not added.
＜比較例５＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１５と同様の手順で比較例５に係る粒子を作製した。 <Comparative Example 5>
Particles according to Comparative Example 5 were produced in the same manner as in Example 15, except that TBACl was not added.
＜比較例６＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１６と同様の手順で比較例６に係る粒子を作製した。 <Comparative Example 6>
Particles according to Comparative Example 6 were produced in the same manner as in Example 16, except that TBACl was not added.
＜比較例７＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１７と同様の手順で比較例７に係る粒子を作製した。 <Comparative Example 7>
Particles according to Comparative Example 7 were prepared in the same manner as in Example 17, except that TBACl was not added.
＜比較例８＞
　ＴＢＡＣｌを添加しなかった点を除き、実施例１８と同様の手順で比較例８に係る粒子を作製した。 <Comparative Example 8>
Particles according to Comparative Example 8 were produced in the same manner as in Example 18, except that TBACl was not added.
（第五工程：複合粒子５から有機オニウムカチオンを取り除く工程）
　実施例１に係る複合粒子５の乾燥粉体を、固形分濃度１％となるようにｐＨ２．５の塩化水素水溶液に加え、超音波洗浄機で５分間処理し、さらにスターラーにて３０分間撹拌した。これにより、目視にて凝集のない懸濁液を得た。この懸濁液を、遠心分離（２５０００ｇ、１０分間）およびデカンテーションにより濃縮し、続いてｐＨ４の塩化水素水溶液に加えて５分間スターラー撹拌してから、遠心分離およびデカンテーションでさらに濃縮した。その後純水で洗浄と濃縮を５回繰り返した。精製、回収した複合粒子を風乾し、さらに室温２５度にて真空乾燥処理を２４時間実施することで乾燥粉体を得た。得られた乾燥粉体をＸ線光電子分光法（ＸＰＳ）にて解析したところ、ＴＢＡＣｌに由来する窒素元は検出されず、有機オニウムカチオンが除去されたことを確認した。乾燥粉体を再び純水に加え、超音波処理したところ、良好な再分散を示した。
　すべての実施例において上記処理を行い、有機オニウムカチオンの除去および良好な再分散を確認した。比較例については、第五工程を行わなかった。 (Fifth step: step of removing organic onium cations from composite particles 5)
The dry powder of composite particles 5 according to Example 1 was added to an aqueous hydrogen chloride solution having a pH of 2.5 so that the solid content concentration was 1%, treated with an ultrasonic cleaner for 5 minutes, and further stirred with a stirrer for 30 minutes. did. As a result, a visually clump-free suspension was obtained. The suspension was concentrated by centrifugation (25000 g, 10 minutes) and decantation, then added to pH 4 aqueous hydrogen chloride solution and stirred for 5 minutes before further concentration by centrifugation and decantation. After that, washing with pure water and concentration were repeated five times. The purified and collected composite particles were air-dried, and further vacuum-dried at room temperature of 25° C. for 24 hours to obtain dry powder. When the resulting dry powder was analyzed by X-ray photoelectron spectroscopy (XPS), nitrogen origin derived from TBACl was not detected, confirming that organic onium cations were removed. The dry powder was again added to pure water and sonicated, showing good redispersion.
All examples were subjected to the above treatment, and removal of organic onium cations and satisfactory redispersion were confirmed. For the comparative example, the fifth step was not performed.
　表２に、実施例および比較例の内容をまとめて示す。 Table 2 summarizes the contents of Examples and Comparative Examples.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表３に、実施例および比較例の評価結果を示す。評価項目および基準は以下の通りである。
（エマルション安定性）
　第三工程で得られたО／Ｗ型エマルションを２４時間静置した後においてＯ／Ｗ型エマルションを光学顕微鏡観察により観察し、１００個の液滴の径を測定し、その最大値を最大液滴径とした。エマルション安定性が低いとクリーミングや凝集、液滴の合一などの不安定化により液滴径が大きくなる。エマルション安定性は、以下のように評価した。
〇（ｇｏｏｄ）：最大液滴径が５０μｍ以下である。
×（ｂａｄ）：最大液滴径が５０μｍを超える。
（複合粒子作製可否）
　複合粒子作製可否は、以下のように評価した。
○（ｇｏｏｄ）：第四工程で得られた粒子を光学顕微鏡にて観察し、球状の複合粒子が多数得られている。
×（ｂａｄ）：第四工程で得られた粒子を光学顕微鏡にて観察し、粒子が球状でない、または複合粒子が凝集した粗大な塊を認める。
　エマルションの安定性が高い場合、重合後もエマルションの液滴の形状が維持される。一方で、重合前や重合中にエマルションが不安定化すると、分離や合一により異形の樹脂や粗大化した樹脂が生じる。 Table 3 shows the evaluation results of Examples and Comparative Examples. Evaluation items and criteria are as follows.
(emulsion stability)
After the O/W type emulsion obtained in the third step was allowed to stand for 24 hours, the O/W type emulsion was observed with an optical microscope, and the diameter of 100 droplets was measured. It was taken as the droplet diameter. If the emulsion stability is low, the droplet size becomes large due to instability such as creaming, aggregation, and coalescence of droplets. Emulsion stability was evaluated as follows.
◯ (good): The maximum droplet diameter is 50 μm or less.
x (bad): the maximum droplet size exceeds 50 μm.
(Possibility of preparing composite particles)
Whether composite particles can be produced was evaluated as follows.
○ (good): The particles obtained in the fourth step were observed with an optical microscope, and a large number of spherical composite particles were obtained.
x (bad): The particles obtained in the fourth step are observed with an optical microscope, and coarse aggregates of non-spherical particles or agglomerated composite particles are observed.
If the emulsion is highly stable, the shape of the emulsion droplets is maintained after polymerization. On the other hand, if the emulsion is destabilized before or during the polymerization, a deformed resin or a coarsened resin is produced due to separation or coalescence.
・複合粒子の収率（％）
　複合粒子の収率は、取得された複合粒子の重量(ｇ)／製造に用いたコア粒子前駆体の樹脂重量(ｇ)×１００から算出した。
・複合粒子の平均粒径（メジアン値）
　複合粒子の平均粒径は、粒子形状画像解析装置（ＰＩＴＡ－０４）を用いて求めた。粗大化した樹脂の塊が存在する場合は、これを除去して測定した。
・複合粒子の粒径均一性
　光学顕微鏡観察により、１００個の粒子の粒径を測定し、粒径の最大値と最小値との差を粒径範囲として算出した。複合粒子の粒径均一性の評価は以下の２段階とした。
○（ｇｏｏｄ）：粒径範囲が５０μｍ以下である。
×（ｂａｄ）：粒径範囲が５０μｍを超える。 ・Yield of composite particles (%)
The yield of the composite particles was calculated by multiplying the weight (g) of the obtained composite particles/the resin weight (g) of the core particle precursor used for production×100.
・Average particle size of composite particles (median value)
The average particle size of the composite particles was determined using a particle shape image analyzer (PITA-04). When coarse resin lumps were present, they were removed and measured.
- Particle Size Uniformity of Composite Particles The particle size of 100 particles was measured by optical microscope observation, and the difference between the maximum and minimum particle sizes was calculated as the particle size range. The particle size uniformity of the composite particles was evaluated in the following two stages.
◯ (good): The particle size range is 50 μm or less.
× (bad): The particle size range exceeds 50 µm.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表３に示すように、各実施例では、微細化セルロース分散液中で様々な種類のコア粒子前駆体が安定性したエマルションを形成し、良好に高収率で、粒子径が小さく均一な複合粒子が形成された。これは、微細化セルロースの分散液に後から各種有機オニウム化合物／アミンを添加して攪拌するという非常に簡便な方法にて、有機オニウム化合物／アミン由来の有機オニウムイオン／アンモニウムイオンが親水性の微細化セルロースの表面の一部に結合することにより表面が疎水化され、コア粒子前駆体への吸着力が向上したことよると考えられる。
　実施例１から実施例８のように、ＴＢＡＣｌ、ＴＢＡＢｒ、ＴＢＡＨ、ＴＭＡＨ、ＤＭＢＡ、ＤＭＳＡ、ステアリルアミン、トリヘキシルアミンといった様々な有機オニウム化合物／アミンを用いた場合にも、良好な結果を得ることが可能であった。 As shown in Table 3, in each example, various types of core particle precursors formed stable emulsions in micronized cellulose dispersions, yielding good high yields, uniform composites with small particle sizes. Particles were formed. This is a very simple method in which various organic onium compounds/amines are added to the finely divided cellulose dispersion and stirred, and the organic onium compounds/organic onium ions/ammonium ions derived from the amines are made hydrophilic. It is believed that the bonding to a part of the surface of the micronized cellulose made the surface hydrophobic and improved the adsorptive power to the core particle precursor.
Good results were also obtained when various organic onium compounds/amines such as TBACl, TBABr, TBAH, TMAH, DMBA, DMSA, stearylamine, and trihexylamine were used as in Examples 1 to 8. was possible.
　図５Ａに示した実施例１に係る複合粒子のＳＥＭ像では、数μｍ以下と粒径が小さく均一な球状粒子が生成されていることが分かる。また、粒子の表面を観察すると繊維状の凹凸が見られ、微細化セルロースが被覆されていることが示唆された。 In the SEM image of the composite particles according to Example 1 shown in FIG. 5A, it can be seen that uniform spherical particles with a small particle size of several μm or less are produced. In addition, fibrous irregularities were observed on the surface of the particles, suggesting that the particles were coated with micronized cellulose.
　更に、驚くべきことに、微細化セルロースのアニオン性官能基に対してＴＢＡＨを１当量未満しか添加していない実施例９から実施例１２においても安定したエマルションが形成され、粒子径の均一な複合粒子を高収率に得ることができた。
　図６Ａおよび図６Ｂに、実施例１０に係る複合粒子のＳＥＭ像を示す。図６Ａおよび図６Ｂの倍率は、図５Ａおよび図５Ｂとそれぞれ同様である。図６Ａより、全体として数μｍ以下と微小な球状粒子が多く生成されており、図６Ｂより、複合粒子の表面には繊維状の凹凸が多数見られ、微細化セルロースからなる被覆層１０が形成されていることがわかる。また、図８に示す粒度分布からも、実施例１０においては全体として微小な粒子が生成されていることが確認できる。 Furthermore, surprisingly, stable emulsions were formed even in Examples 9 to 12, in which less than 1 equivalent of TBAH was added to the anionic functional groups of the micronized cellulose, and composites with a uniform particle size were formed. A high yield of particles could be obtained.
6A and 6B show SEM images of composite particles according to Example 10. FIG. The magnifications of FIGS. 6A and 6B are the same as in FIGS. 5A and 5B, respectively. As shown in FIG. 6A, many fine spherical particles with a size of several μm or less are produced as a whole, and as shown in FIG. It can be seen that Also, from the particle size distribution shown in FIG. 8, it can be confirmed that fine particles are produced in Example 10 as a whole.
　実施例１３から実施例１６に示されるように、ＩＢ－ＸＡ、ｐＭｅ－Ｓｔ、ＵＡ４２００、ＰＣＬといった、ＩＢ－Ｘ以外の様々なコア前駆体、コア粒子においても、高収率で、粒子径の均一な複合粒子を得ることができた。
　実施例１７および実施例１８に示されるように、ＣＭ化、リン酸エステル化といった、ＴＥＭＰＯ酸化以外の各種アニオン性官能基を有する微細化セルロースを使用しても、有機オニウム化合物／アミンを後から添加する簡便な方法によって、微細化セルロース表面を疎水化し、高収率にて粒子径の均一な複合粒子を得ることができた。 As shown in Examples 13 to 16, various core precursors and core particles other than IB-X, such as IB-XA, pMe-St, UA4200, and PCL, have high yields and particle diameters. Uniform composite particles could be obtained.
As shown in Examples 17 and 18, even when using finely divided cellulose having various anionic functional groups other than TEMPO oxidation, such as CM and phosphate esterification, organic onium compounds/amines are added afterward. By a simple addition method, the surface of the micronized cellulose was hydrophobized, and composite particles with a uniform particle size could be obtained at a high yield.
　比較例１から比較例７においても複合粒子を得ることができたが、表３に示すように、エマルション安定性が低いために実施例１～１８と比較し、収率が下がり、粒径が大きく、粒径の均一性も低かった。図７Ａおよび図７Ｂに、比較例２に係る複合粒子の乾燥粉体のＳＥＭ像を示す。図７Ａおよび図７Ｂの倍率は、図５Ａおよび図５Ｂとそれぞれ同様である。図７Ａより、比較例１では、粗大化した複合粒子が多数存在し、粒度分布が均一でないことが分かる。粗大化した複合粒子においては、図７Ｂに示すようにコア粒子の表面の多くが露出しており、微細化セルロースはわずかしか結合していなかった。
　比較例１から比較例８の複合粒子を光学顕微鏡にて観察したところ、最大粒径が５０μｍ以上であり、粒度分布計ＰＩＴＡ－０４のセルに詰まる可能性があったため、粒度分布測定を実施できなかった。比較例２において粗大粒子を取り除き、粒度分布計にて粒度分布を評価した。すなわち、図８に示されている比較例２の粒度分布は粗大粒子を取り除いた後の粒度分布である。図８のように実施例１、実施例１０と比較して比較例２の粒子径が大きい傾向が認められ、粒子径のバラつきも大きかった。 Composite particles could also be obtained in Comparative Examples 1 to 7, but as shown in Table 3, the emulsion stability was low and the yield was lower than in Examples 1 to 18. It was large and the uniformity of particle size was low. 7A and 7B show SEM images of dry powder of composite particles according to Comparative Example 2. FIG. The magnifications of FIGS. 7A and 7B are similar to FIGS. 5A and 5B, respectively. As can be seen from FIG. 7A, in Comparative Example 1, a large number of coarsened composite particles exist and the particle size distribution is not uniform. In the coarsened composite particles, as shown in FIG. 7B, most of the surface of the core particles was exposed, and only a small amount of finely divided cellulose was bound.
When the composite particles of Comparative Examples 1 to 8 were observed with an optical microscope, the maximum particle size was 50 μm or more, and there was a possibility that the cell of the particle size distribution meter PITA-04 was clogged, so particle size distribution measurement could not be performed. I didn't. In Comparative Example 2, coarse particles were removed, and the particle size distribution was evaluated using a particle size distribution meter. That is, the particle size distribution of Comparative Example 2 shown in FIG. 8 is the particle size distribution after removing coarse particles. As shown in FIG. 8, the particle size of Comparative Example 2 tended to be larger than those of Examples 1 and 10, and the variation in particle size was also large.
　本発明に係る複合粒子は、添加剤としての添加効率、樹脂との混練効率が向上し、また輸送効率向上や腐敗防止の観点からコスト削減にも寄与するなど、産業実施の観点から好ましい効果が得られる。本複合粒子は、粒子表面の微細化セルロースおよびコア粒子を構成するポリマーの特性を活かすことによって、色材、吸着剤、化粧顔料、徐放材、消臭剤、抗菌性医療用部材、パーソナルケア用品向け抗菌性物品、包装材料、色素増感太陽電池、光電変換材料、光熱変換材料、遮熱材料、光学フィルター、ラマン増強素子、画像表示素子、磁性粉、触媒担持体、ドラッグデリバリーシステム、などに適用することができる。 The composite particles according to the present invention have favorable effects from the viewpoint of industrial implementation, such as improving the addition efficiency as an additive and the efficiency of kneading with a resin, and contributing to cost reduction from the viewpoint of improving transportation efficiency and preventing spoilage. can get. By utilizing the properties of the micronized cellulose on the surface of the particles and the polymer that constitutes the core particles, the composite particles can be used for coloring materials, adsorbents, cosmetic pigments, sustained-release materials, deodorants, antibacterial medical materials, personal care products, etc. Antibacterial products for supplies, packaging materials, dye-sensitized solar cells, photoelectric conversion materials, photothermal conversion materials, heat shielding materials, optical filters, Raman enhancement elements, image display elements, magnetic powders, catalyst carriers, drug delivery systems, etc. can be applied to
１　微細化セルロース
２　コア粒子前駆体
３　コア粒子
４　分散溶媒
５　複合粒子
６　液滴
７ａ　有機オニウムカチオン／アンモニウムイオン
１０　被覆層 1 micronized cellulose 2 core particle precursor 3 core particle 4 dispersion solvent 5 composite particle 6 droplet 7a organic onium cation/ammonium ion 10 coating layer

Claims (14)

  1. 　セルロース原料を分散溶媒中で解繊して、微細化セルロースが分散された微細化セルロース分散液を得る第一工程と、
    　前記微細化セルロース分散液に、有機オニウム化合物またはアミンを添加して、有機オニウムイオンまたはアンモニウムイオンが結合した微細化セルロースを含むイオン結合微細化セルロース分散液を得る第二工程と、
    　前記イオン結合微細化セルロース分散液中においてコア粒子前駆体を含む液滴をエマルションとして安定化させる第三工程と、
    　前記コア粒子前駆体を固体化させてコア粒子とし、前記コア粒子と不可分に結合した前記微細化セルロースが前記コア粒子を被覆した複合粒子を得る第四工程と、
    　を備える、
    　複合粒子の製造方法。     a first step of defibrating a cellulose raw material in a dispersion solvent to obtain a micronized cellulose dispersion in which micronized cellulose is dispersed;
    a second step of adding an organic onium compound or an amine to the micronized cellulose dispersion to obtain an ion-bonded micronized cellulose dispersion containing micronized cellulose bound with organic onium ions or ammonium ions;
    a third step of stabilizing droplets containing core particle precursors as an emulsion in the ionically bonded micronized cellulose dispersion;
    a fourth step of solidifying the core particle precursor to form core particles and obtaining composite particles in which the core particles are coated with the micronized cellulose that is inseparably bound to the core particles;
    comprising
    A method for producing composite particles.
  2. 　前記第四工程の後に、前記微細化セルロースと結合した前記有機オニウムイオンまたはアンモニウムイオンを除去する第五工程をさらに備える、
    　請求項１に記載の複合粒子の製造方法。     After the fourth step, further comprising a fifth step of removing the organic onium ion or ammonium ion bound to the micronized cellulose,
    A method for producing composite particles according to claim 1 .
  3. 　前記有機オニウム化合物またはアミンの添加量は、前記微細化セルロースに含まれるアニオン性官能基に対して０．０２当量以上１．８当量以下である、
    　請求項１または２に記載の複合粒子の製造方法。     The amount of the organic onium compound or amine added is 0.02 equivalent or more and 1.8 equivalent or less with respect to the anionic functional group contained in the micronized cellulose.
    3. A method for producing composite particles according to claim 1 or 2.
  4. 　前記有機オニウム化合物またはアミンが有するカチオン構造の対イオンが塩化物イオンまたは臭化物イオンである、
    　請求項１から請求項３のいずれか一項に記載の複合粒子の製造方法。     The counter ion of the cationic structure of the organic onium compound or amine is a chloride ion or a bromide ion,
    The method for producing composite particles according to any one of claims 1 to 3.
  5. 　前記複合粒子の収率が６０％以上である、
    　請求項１から請求項４のいずれか一項に記載の複合粒子の製造方法。     The yield of the composite particles is 60% or more,
    The method for producing composite particles according to any one of claims 1 to 4.
  6. 　少なくとも１種類のポリマーを含むコア粒子と、
    　前記コア粒子と不可分に結合して前記コア粒子の表面上に配置された、アニオン性官能基を有する微細化セルロースと、
    　を備え、
    　前記微細化セルロースの少なくとも一部に有機オニウムイオンまたはアンモニウムイオンが結合している、
    　複合粒子。     a core particle comprising at least one polymer;
    a micronized cellulose having an anionic functional group, which is inseparably bonded to the core particle and arranged on the surface of the core particle;
    with
    Organic onium ions or ammonium ions are bound to at least part of the micronized cellulose,
    Composite particles.
  7. 　前記有機オニウムイオンは、窒素、リン、水素、硫黄から選ばれる少なくとも１種類の原子を含む、
    　請求項６に記載の複合粒子。     The organic onium ion contains at least one type of atom selected from nitrogen, phosphorus, hydrogen, and sulfur.
    Composite particles according to claim 6 .
  8. 　前記有機オニウムイオンが第４級アンモニウムイオンである、
    　請求項６または７に記載の複合粒子。     wherein the organic onium ion is a quaternary ammonium ion;
    Composite particles according to claim 6 or 7.
  9. 　前記微細化セルロースの少なくとも一部に、前記アンモニウムイオンとして第１級アンモニウムイオン、第２級アンモニウムイオン、第３級アンモニウムイオンのいずれかが結合している、
    　請求項６に記載の複合粒子。     Any one of primary ammonium ions, secondary ammonium ions, and tertiary ammonium ions is bound to at least a portion of the micronized cellulose as the ammonium ions.
    Composite particles according to claim 6 .
  10. 　前記複合粒子の平均粒径が５０μｍ以下である、
    　請求項６から請求項９のいずれか一項に記載の複合粒子。     The average particle diameter of the composite particles is 50 μm or less,
    Composite particles according to any one of claims 6 to 9.
  11. 　前記微細化セルロースの少なくとも一部に、更に金属イオンが結合している、
    　請求項６から請求項１０のいずれか一項に記載の複合粒子。     A metal ion is further bound to at least a portion of the micronized cellulose,
    Composite particles according to any one of claims 6 to 10.
  12. 　前記ポリマーは、重合性官能基を有する少なくとも１種類以上のモノマーが重合されたものである、
    　請求項６から請求項１１のいずれか一項に記載の複合粒子。     The polymer is obtained by polymerizing at least one type of monomer having a polymerizable functional group,
    Composite particles according to any one of claims 6 to 11.
  13. 　前記ポリマーが熱可塑性ポリマーである、
    　請求項６から請求項１２のいずれか一項に記載の複合粒子。     wherein said polymer is a thermoplastic polymer;
    Composite particles according to any one of claims 6 to 12.
  14. 　前記コア粒子が生分解性材料を含有する、
    　請求項６から請求項１３のいずれか一項に記載の複合粒子。     wherein the core particle contains a biodegradable material;
    Composite particles according to any one of claims 6 to 13.
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