WO2014171430A1 - Molded foam - Google Patents

Molded foam Download PDF

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Publication number
WO2014171430A1
WO2014171430A1 PCT/JP2014/060656 JP2014060656W WO2014171430A1 WO 2014171430 A1 WO2014171430 A1 WO 2014171430A1 JP 2014060656 W JP2014060656 W JP 2014060656W WO 2014171430 A1 WO2014171430 A1 WO 2014171430A1
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WO
WIPO (PCT)
Prior art keywords
resin composition
cellulose
foam
foamed
mass
Prior art date
Application number
PCT/JP2014/060656
Other languages
French (fr)
Japanese (ja)
Inventor
圭助 木村
中井　美穂
頌平 熊澤
行成 祢宜
Original Assignee
ユニチカ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ユニチカ株式会社 filed Critical ユニチカ株式会社
Priority to JP2015512475A priority Critical patent/JP6351574B2/en
Publication of WO2014171430A1 publication Critical patent/WO2014171430A1/en

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Classifications

    • 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
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/0066—Use of inorganic compounding ingredients
    • C08J9/0071—Nanosized fillers, i.e. having at least one dimension below 100 nanometers
    • C08J9/0076—Nanofibres
    • 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
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
    • C08J9/10—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing nitrogen, the blowing agent being a compound containing a nitrogen-to-nitrogen bond
    • C08J9/102—Azo-compounds
    • C08J9/103—Azodicarbonamide
    • 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
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/34—Chemical features in the manufacture of articles consisting of a foamed macromolecular core and a macromolecular surface layer having a higher density than the core
    • 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
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
    • C08J2201/03—Extrusion of the foamable blend
    • 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
    • C08J2203/00—Foams characterized by the expanding agent
    • C08J2203/04—N2 releasing, ex azodicarbonamide or nitroso compound
    • 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
    • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
    • C08J2377/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
    • 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
    • C08J2401/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2401/02—Cellulose; Modified cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers

Definitions

  • the present invention relates to a foam molded article comprising a resin composition using a polyamide resin, having a good surface appearance and excellent impact resistance.
  • Polyamide resin is excellent in properties such as mechanical properties, chemical resistance, heat resistance, and moldability, and the molded body has been widely used for automobile parts, electronic parts and the like.
  • molded articles are molded using a resin composition reinforced by blending polyamide resin with an inorganic filler such as glass fiber, carbon fiber, talc, or clay.
  • these reinforcing materials have a problem that the mechanical properties and thermal properties of the molded body cannot be improved unless they are blended in a large amount, and the mass of the resulting molded body increases due to its high specific gravity. It was.
  • glass fiber, carbon fiber or the like is used as the reinforcing material
  • the obtained molded product has a problem that warpage becomes large.
  • talc, clay, etc. are used as reinforcing materials, when the obtained molded product is discarded, these reinforcing materials remain as incineration residues, so they are buried in the soil and semi-permanently in the ground. There was a problem of remaining.
  • cellulose has been used as a reinforcing material for resin materials.
  • Cellulose includes those obtained from trees, those obtained from non-wood resources such as rice, cotton, kenaf and hemp, and bacterial cellulose produced by microorganisms. Cellulose is present in large quantities on the earth. . Cellulose is excellent in mechanical properties. By containing this in the resin, an effect of improving the properties of the resin composition, that is, the properties of the molded product is expected.
  • a foamed molded product obtained by foaming by adding a foaming agent to a polyamide resin has been proposed as a molded product that is reduced in weight while utilizing the characteristics of the polyamide resin as described above.
  • Patent Document 1 discloses a thermoplastic resin molded article having a foam structure, which is made of a thermoplastic resin composition containing a thermoplastic resin and cellulose fibers, and also describes a polyamide resin as the thermoplastic resin.
  • mold extruder is used in order to mix a thermoplastic resin and a cellulose fiber.
  • a method of incorporating cellulose into the thermoplastic resin a method of melt-mixing the resin and cellulose fiber is common.
  • the cellulose fibers are mixed in the resin in an aggregated state, they are not uniformly dispersed, and the average fiber diameter of the cellulose fibers is large.
  • Patent Document 1 is intended to obtain a molded article having a touch similar to that of a wooden surface, and in order to achieve this object, a large amount of cellulose fibers are contained to increase the surface roughness of the molded article. It is said. Therefore, the foam molded article described in Patent Document 1 does not have a large amount of foam cells that are uniform in size and fine, and therefore the foam molded article is inferior in surface appearance and has low impact resistance. It was.
  • the present invention solves the above problems, and is a foamed molded article comprising a resin composition containing a polyamide resin and cellulose fibers, and has a large amount of foam cells that are uniform in size and fine,
  • An object of the present invention is to provide a foam molded article having a good surface appearance and excellent impact resistance.
  • the gist of the present invention is as follows.
  • a resin composition comprising 0.1 to 10 parts by mass of cellulose fibers having an average fiber diameter of 10 ⁇ m or less and 0.01 to 15 parts by mass of a foam nucleating agent with respect to 100 parts by mass of a polyamide resin, A foamed molded article having a foamed cell.
  • the polyamide resin and the cellulose fiber constituting the resin composition are obtained by performing a polymerization reaction of the monomer constituting the polyamide resin in the presence of the cellulose fiber containing water.
  • the foamed molded article of the present invention is obtained by foaming a resin composition containing a specific amount of cellulose fibers having a small average fiber diameter and a foam nucleating agent. It will have a large amount. For this reason, the foamed molded article of the present invention has excellent surface appearance and excellent impact resistance.
  • molding processing can be performed by a core back injection molding method, and foam having a core layer and a skin layer. It can be set as a molded body.
  • foaming molding of the present invention includes swirl marks (foam marks generated on the surface of the molding), silver streaks (silver marks generated along the flow direction of the resin on the molding surface), sink marks ( It is excellent in surface appearance without causing a dent or the like on the surface of the molded body.
  • the foamed molded article of the present invention comprises a resin composition containing a polyamide resin, cellulose fibers having an average fiber diameter of 10 ⁇ m or less, and a foam nucleating agent, and has foam cells.
  • the polyamide resin used in the present invention refers to a polymer having an amide bond formed from an amino acid, lactam or diamine and a dicarboxylic acid.
  • Examples of monomers that form such a polyamide resin include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and paraaminomethylbenzoic acid.
  • Examples of the lactam include ⁇ -caprolactam and ⁇ -laurolactam.
  • diamines examples include tetramethylene diamine, hexamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,4- / 2,4,4-trimethylhexamethylene diamine, and 5-methyl.
  • Dicarboxylic acids include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5- Examples include sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and diglycolic acid.
  • the polyamide resin used in the present invention includes polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebaca. Mido (nylon 610), polyhexamethylene dodecane (nylon 612), polyundecane methylene adipamide (nylon 116), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polytrimethylhexamethylene terephthalamide (Nylon TMHT), polyhexamethylene terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide / isophthalamide (nylon 6T / 6I), polybis (4-aminocyclo) Xyl) methane dodecamide (nylon PACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (nylon PACM
  • the above polyamide resin is produced by a polymerization method described later, or by further using a solid phase polymerization method.
  • the cellulose fibers used in the present invention include those derived from wood, rice, cotton, hemp, kenaf and the like, as well as those derived from organisms such as bacterial cellulose, valonia cellulose and squirt cellulose. Also included are regenerated cellulose, cellulose derivatives and the like.
  • the dispersibility of the cellulose fiber to the polyamide resin and the affinity between the polyamide resin and the cellulose fiber are important.
  • the cellulose fiber have properties such as hydroxyl groups as much as possible, it is important to increase the surface area of the cellulose fiber. For this reason, it is necessary to use as fine a cellulose fiber as possible.
  • the cellulose fiber contained in the resin composition in the present invention needs to have an average fiber diameter of 10 ⁇ m or less, and the average fiber diameter is preferably 1 ⁇ m or less, and preferably 500 nm or less. More preferably, it is preferably 300 nm or less, and most preferably 40 to 100 nm.
  • the average fiber diameter of the cellulose fibers contained in the resin composition exceeds 10 ⁇ m, the surface area of the cellulose fibers cannot be increased, and it becomes difficult to improve the dispersibility and affinity for the polyamide resin. For this reason, the foamed molded article obtained does not have uniform foam cell size, the foam cell becomes large, and the cellulose fibers are visually confirmed, resulting in poor surface appearance and impact resistance. .
  • cellulose fibers having an average fiber diameter of 10 ⁇ m or less In order to make the average fiber diameter of the cellulose fibers in the resin composition 10 ⁇ m or less, it is necessary to use cellulose fibers having an average fiber diameter of 10 ⁇ m or less. As such a cellulose fiber, what was microfibrillated by tearing a cellulose fiber is preferable.
  • Various pulverizing apparatuses such as a ball mill, a stone mill, a high-pressure homogenizer, and a mixer can be used as means for microfibrillation.
  • a cellulose fiber what is marketed can use "Serish" by Daicel FineChem, for example.
  • an aggregate of cellulose fibers taken out as scrap yarn can be used.
  • the production process of the textile product includes spinning, woven fabric, nonwoven fabric production, and other textile product processing. Since these cellulose fiber aggregates are scrap fibers after the cellulose fibers have undergone these steps, the cellulose fibers are refined.
  • bacterial cellulose produced by bacteria can be used as the cellulose fiber, and for example, those produced using an Acetobacter acetic acid bacterium as a producing bacterium can be used.
  • Plant cellulose is composed of cellulose molecular chains converged and formed by bundles of very thin microfibrils, whereas cellulose produced from acetic acid bacteria originally has a width of 20-50 nm. It is in the form of a ribbon, and forms an extremely fine network compared to plant cellulose.
  • a refined cellulose fiber obtained by oxidizing the cellulose fiber in the presence of an N-oxyl compound, followed by washing with water and physical defibrating may be used.
  • N-oxyl compounds such as 2,2,6,6-tetramethylpiperidine-1-oxyl radical (hereinafter referred to as TEMPO) as described in Cellulose (1998) 5,153-164. preferable.
  • TEMPO 2,2,6,6-tetramethylpiperidine-1-oxyl radical
  • Such a compound is added to the reaction aqueous solution in a catalytic amount range.
  • sodium hypochlorite or sodium chlorite is added as a co-oxidant, and the reaction is allowed to proceed by adding an alkali metal bromide.
  • An alkaline compound such as an aqueous sodium hydroxide solution is added to maintain the pH at around 10, and the reaction is continued until no change in pH is observed.
  • the reaction temperature may be room temperature.
  • Various methods such as filtration and centrifugation can be employed for washing. Then, using various pulverizers as described above, it is possible to obtain refined cellulose fibers through a physical defibrating process.
  • the cellulose fiber in the resin composition in the present invention preferably has an aspect ratio (average fiber length / average fiber diameter) which is a ratio of an average fiber diameter to an average fiber length of 10 or more, and more preferably 50 or more. It is preferable that it is 100 or more.
  • the aspect ratio is 10 or more, the mechanical properties of the obtained foamed molded product are easily improved.
  • the content of the cellulose fiber in the resin composition constituting the foamed molded article of the present invention needs to be 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin.
  • the amount is preferably 5 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass.
  • foaming is difficult to foam in foam molding, so foam molding having a large amount of uniform and fine foam cells. A body cannot be obtained, the surface appearance is inferior, and the foaming ratio is lower than the set expansion ratio.
  • the content of the cellulose fiber exceeds 10 parts by mass with respect to 100 parts by mass of the polyamide resin, it becomes difficult to contain the cellulose fiber (A) in the resin composition, or the obtained foamed molded article is A foam cell having a large cell diameter is likely to be generated, the size of the foam cell is not uniform, and the surface appearance and impact resistance are poor.
  • the resin composition in the present invention by obtaining the resin composition in the present invention by a production method as described later, even if the cellulose fiber content is small, it becomes a resin composition uniformly dispersed in the polyamide resin.
  • foam molding it is possible to obtain a foam molded article that is sufficiently foamed, has a uniform size, and has a large amount of fine foam cells. Furthermore, the impact resistance of the obtained foamed molded product can be increased.
  • cellulose fibers have a very high affinity with water, and the smaller the average fiber diameter, the better the dispersion state with respect to water. Further, when water is lost, cellulose fibers are strongly aggregated by hydrogen bonding, and once aggregated, it becomes difficult to achieve a dispersion state similar to that before aggregation. In particular, this tendency becomes more prominent as the average fiber diameter of the cellulose fibers decreases. Therefore, the cellulose fiber is preferably combined with the polyamide resin in a state containing water. Therefore, in the present invention, a polyamide resin composition containing cellulose fibers is obtained by performing a polymerization reaction of monomers constituting the polyamide resin in the presence of cellulose fibers containing water during the polymerization of the polyamide resin. It is preferable to take the method of obtaining. Such a production method makes it possible to uniformly disperse the cellulose fibers in the polyamide resin without aggregating them. Details of this manufacturing method will be described below.
  • a polyamide resin composition containing cellulose fibers (resin composition A) containing cellulose fibers in advance. That is, a polyamide resin having an average fiber diameter of 10 ⁇ m or less is obtained by conducting a polymerization reaction of monomers constituting the polyamide resin in the presence of water-containing cellulose fibers to obtain a polyamide resin. It is preferable to prepare a resin composition (resin composition A). For example, the monomer which comprises a polyamide resin and the aqueous dispersion of the cellulose fiber whose average fiber diameter is 10 micrometers or less are mixed, and a polymerization reaction is performed.
  • the aqueous dispersion of cellulose fibers in this preparation method is obtained by dispersing cellulose fibers having an average fiber diameter of 10 ⁇ m or less in water, and the content of cellulose fibers in the aqueous dispersion is 0.01 to 50% by mass. It is preferable to do.
  • the aqueous dispersion of cellulose fibers can be obtained by stirring purified water and cellulose fibers with a mixer or the like. And the aqueous dispersion of a cellulose fiber and the monomer which comprises a polyamide resin are mixed, and it is set as a uniform dispersion by stirring with a mixer etc.
  • the dispersion is heated, and the temperature is raised to 150 to 270 ° C., followed by stirring to cause a polymerization reaction.
  • water in the aqueous dispersion of cellulose fibers can be discharged by gradually discharging water vapor when the dispersion is heated.
  • a catalyst such as phosphoric acid or phosphorous acid may be added as necessary.
  • a foam nucleating agent may be added during the polyamide polymerization.
  • finish of a polymerization reaction after paying out the obtained resin composition, it is preferable to cut
  • a cellulose fiber aqueous dispersion obtained by immersing bacterial cellulose in purified water and replacing the solvent may be used.
  • cellulose fibers having an average fiber diameter of 10 ⁇ m or less are used, and the cellulose fibers are subjected to a polymerization reaction in an aqueous dispersion, thereby being subjected to a polymerization reaction with good dispersibility.
  • the cellulose fibers subjected to the polymerization reaction are improved in dispersibility by agitation with the monomer and water during the polymerization reaction and by stirring at the above temperature conditions, and the fibers aggregate. It is possible to obtain a resin composition A in which cellulose fibers having a small average fiber diameter are well dispersed.
  • the cellulose fibers contained in the mixture after the completion of the polymerization reaction are more than the average fiber diameter of the cellulose fibers added before the polymerization reaction.
  • the average fiber diameter and fiber length may be smaller.
  • the step of drying the cellulose fibers is not necessary, and the production can be performed without the step of causing the scattering of fine cellulose fibers, so that the resin composition A can be obtained with good operability. Become. Moreover, since it is not necessary to replace water with an organic solvent for the purpose of uniformly dispersing the monomer and cellulose, the handling is excellent and the discharge of chemical substances can be suppressed during the production process.
  • the resin composition A in the present invention is obtained by performing a polymerization reaction of monomers constituting the polyamide resin in the presence of cellulose fibers containing water.
  • the resin composition A means one that also contains the additive.
  • the relative viscosity of the resin composition A prepared by the above method is not particularly limited, but is preferably 1.5 to 5.0, and more preferably 1.7 to 4.0. When the relative viscosity is less than 1.5, it is difficult to form uniform foam cells, foam moldability is lowered, and mechanical properties are also lowered. On the other hand, when the relative viscosity exceeds 5.0, the fluidity of the resin composition A is lowered, and the foam moldability is lowered.
  • 96% sulfuric acid was used as a solvent, and the temperature was 25 ° C. and the concentration was 1 g / 100 ml.
  • the elongation viscosity of the resin composition A is preferably 8.00 ⁇ 10 3 to 6.00 ⁇ 10 5 Pa ⁇ s, and more preferably 1.00 ⁇ 10 4 to 9.50 ⁇ 10 4 Pa ⁇ s. It is preferable that When the extensional viscosity is within the above range, it has a viscosity suitable for foaming, the foam cell size is uniform, and a large number of foam cells of appropriate size are formed. Excellent in properties.
  • the resin composition A having an elongation viscosity of 1.00 ⁇ 10 4 to 9.50 ⁇ 10 4 Pa ⁇ s, which is a preferable range, has the average fiber diameter of the cellulose fibers in the resin composition as described above.
  • the content can be adjusted to 40 to 100 nm, and the cellulose fiber content can be adjusted to 0.5 to 5 parts by mass, which is the most preferable range described above. Even if the average fiber diameter of the cellulose fibers in the resin composition A exceeds the most preferable range of 40 to 100 nm, the elongation viscosity of the resin composition A is 1.00 ⁇ 10 4 to 9.50 ⁇ . Although it may be in the range of 10 4 Pa ⁇ s, when the average fiber diameter of the cellulose fibers exceeds 100 nm, the resulting foamed molded product has foam cells having a large cell diameter and tends to be somewhat inferior in uniformity. Therefore, in the present invention, the resin composition A has an average fiber diameter of 40 to 100 nm and an elongational viscosity of 1.00 ⁇ 10 4 to 9.50 ⁇ 10 4 Pa ⁇ s. Most preferred.
  • the resin composition in the present invention contains a foam nucleating agent in addition to the above-described polyamide resin and cellulose fiber (resin composition A).
  • foam nucleating agent used in the present invention include titanium oxide, talc, kaolin, clay, calcium silicate, silica, sodium citrate, calcium carbonate, diatomaceous earth, calcined perlite, zeolite, bentonite, glass, limestone, calcium sulfate, aluminum oxide. , Titanium oxide, magnesium carbonate, sodium carbonate, ferric carbonate, polytetrafluoroethylene powder, and the like.
  • the content of the foam nucleating agent in the resin composition is required to be 0.01 to 15 parts by mass with respect to 100 parts by mass of the polyamide resin, and preferably 0.1 to 12 parts by mass. Further, it is preferably 0.2 to 8 parts by mass, and more preferably 0.2 to 5 parts by mass.
  • the content of the foam nucleating agent is less than 0.01 parts by mass, the resulting foamed molded product does not have the effect of adding the foam nucleating agent, and the bubbles are coarse and foaming tends to be insufficient. The apparent overall density is large, and the surface appearance is inferior.
  • the content of the foam nucleating agent exceeds 15 parts by mass, the number of bubbles becomes excessive and bubble breakage is likely to occur, and the foamed molded article is inferior in surface appearance.
  • the resin composition in this invention can be manufactured by mixing a foaming nucleating agent with the resin composition A which consists of the polyamide resin and cellulose fiber obtained by the said preparation method.
  • Examples of the mixing method include mixing during melt kneading and mixing by addition during polymerization.
  • the resin composition in the present invention may contain other polymers as long as the characteristics are not significantly impaired.
  • Such polymers include polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, natural rubber, chlorinated butyl rubber, elastomers such as chlorinated polyethylene, And acid-modified products thereof such as maleic anhydride, styrene-maleic anhydride copolymer, styrene-phenylmaleimide copolymer, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyvinylidene fluoride, polysulfone, polyphenylene sulfide , Polyethersulfone, phenoxy resin, polyphenylene ether, polymethyl methacrylate, polyether ketone, polyarylate, polycarbonate, polytetrafluoro
  • the resin composition in the present invention has layered silicates such as swellable mica, non-swellable mica, and synthetic smectite, glass fiber, carbon fiber, talc, clay, mica, wax, and the like, as long as the characteristics are not significantly impaired.
  • Contains reinforcements such as lastite, calcium carbonate, barium sulfate, heat stabilizers, antioxidants, pigments, anti-coloring agents, weathering agents, flame retardants, plasticizers, crystal nucleating agents, mold release stabilizers, etc.
  • the pigment include nigrosine, carbon black, titanium dioxide, zinc white, zinc sulfide, lithopone, lead white, antimony white, calcium carbonate, alumina white, and metal powder pigment.
  • the foamed molded product of the present invention is composed of the above resin composition and has foamed cells.
  • the resin composition contains a specific amount of cellulose fibers having a small average fiber diameter and a foam nucleating agent, by foaming this resin composition, a large amount of foam cells that are uniform in size and fine are produced.
  • a foamed molded product containing is obtained. Formation of such a foam-molded product has a structure in which the polyamide resin is cross-linked by containing an appropriate amount of fine cellulose fibers in the polyamide resin, and the elongation viscosity of the polyamide resin composition containing cellulose is increased. Furthermore, it is considered that this is due to containing an appropriate amount of a foam nucleating agent in such a polyamide resin.
  • the foaming molding of this invention has a foam cell, it is comprised especially from a core layer and a skin layer, and it is preferable that a core layer has a foam cell.
  • a foamed molded article having a core layer and a skin layer which is molded by a core back injection molding method, is preferable.
  • the core back injection molding method is a molding method in which the crystallization of the resin composition is promoted to some extent during the formation of the skin layer, and then the core portion is retracted.
  • a resin composition having a high crystallization speed is molded by this method, the skin layer is crystallized and at the same time, the resin composition of the core layer portion is crystallized. Can't get.
  • the resin composition constituting the foamed molded article of the present invention has a small average fiber diameter of cellulose fibers contained therein, the crystallization speed of the polyamide resin is not increased, and it has moderate crystallinity.
  • a foamed molded article having a core layer and a skin layer can be obtained.
  • the foamed molded product of the present invention having such a core layer and skin layer is excellent in surface appearance and surface smoothness without causing swirl marks, silver streaks, sink marks and the like in the skin layer. And it can be set as the foaming molding excellent also in impact resistance by having a skin layer.
  • the thickness ratio (core layer / skin layer) of the core layer and the skin layer in the foamed molded article of the present invention is preferably 1/5 to 5/1.
  • the thickness of the skin layer is larger than this range, the number of foamed cells is reduced, the apparent overall density is increased, and tends to exceed 1.1 g / cm 3 .
  • the thickness of the skin layer is smaller than this range, it is difficult to obtain the excellent surface appearance and surface smoothness as described above, and the impact resistance tends to be inferior.
  • the foamed cell of the foamed molded product of the present invention can have a fine size.
  • the maximum cell diameter of the foam cell is preferably 2 mm or less, more preferably 1.5 mm or less, and most preferably 0.9 mm or less. When the maximum cell diameter exceeds 2 mm, the foamed molded article is inferior in surface appearance, does not have impact resistance, and tends to vary due to mechanical properties.
  • the foamed cells of the foamed molded product of the present invention can be made uniform in size.
  • the uniformity was evaluated by the difference between the maximum cell diameter and the average cell diameter of the foamed cells (maximum cell diameter ⁇ average cell diameter). That is, if this difference is small, the foamed cells are assumed to be uniform.
  • the difference between the maximum cell diameter and the average cell diameter is preferably 1.3 mm or less, more preferably 1.1 mm or less, and most preferably 0.6 mm or less. If this difference exceeds 1.3 mm, the foamed cells have poor uniformity, and the foamed molded product is likely to break starting from the foamed cells when pressure is applied, such as impact resistance. The mechanical properties may be lowered, and the mechanical properties are likely to vary.
  • the foamed molded article of the present invention is measured according to JIS K 7222, and the calculated apparent total density is preferably 1.1 g / cm 3 or less, more preferably 0.9 g / cm 3 or less. Most preferably, it is 0.7 g / cm 3 or less. If the foamed molded body has an apparent total density exceeding 1.1 g / cm 3 , the effect of reducing the weight becomes insufficient. In addition, when the apparent overall density is less than 0.2 g / cm 3 , the amount of the foamed cell is excessively increased, and the impact resistance tends to be low.
  • the foam molded body of the present invention can be obtained by forming a core layer and a skin layer by a core back injection molding method using, for example, a mold having a mirror finish by polishing the mold surface with an abrasive. Can be mirror-finished.
  • a mirror-finished foam molded article is preferably colored black, and is preferably molded using a resin composition containing a black pigment.
  • the black pigment in the present invention include black pigments and black dyes. Specific examples include carbon black, nigrosine, titanium-iron composite oxide, and aniline black. Two or more types of black pigments may be mixed and used.
  • the black pigment content in the foamed molded product of the present invention is preferably 0.1 to 5.0 parts by mass, more preferably 0.1 to 3 parts by mass, with respect to 100 parts by mass of the polyamide resin. preferable.
  • the foamed molded article of the present invention can be obtained by applying a textured surface by forming a core layer and a skin layer by a core back injection molding method using a textured finish mold.
  • the foamed molded product of the present invention is excellent in impact resistance as described above.
  • the impact resistance was evaluated by using notch-free Charpy impact strength according to JIS K 7111-1, using a test piece obtained by cutting a foamed molded product.
  • Charpy impact strength was performed in expanded molded article is preferably at 28kJ / m 2 or more, more preferably 30 kJ / m 2 or more. If the foamed molded article has a Charpy impact strength of less than 28 kJ / m 2 , it has no impact resistance and is not practical.
  • the foamed molded article of the present invention is obtained by foam-molding the above resin composition.
  • foaming agents that can be used for foam molding include pyrolytic foaming agents such as azo, N-nitroso, and heterocyclic nitrogen. Examples thereof include organic compounds containing and decomposable groups such as sulfonyl hydrazide groups, and inorganic compounds such as ammonium carbonate and sodium hydrogen carbonate.
  • azodicarbonamide azobisisobutyronitrile, azocyclohexylnitrile, diazoaminobenzene, dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosotephthalamide
  • benzenesulfonyl Hydrazide 4,4'-oxy-bis (benzenesulfonyl) hydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4-toluenesulfonyl hydrazide, 4,4'-oxy-bis (benzenesulfonyl) semicarbazide
  • 4- Examples include toluenesulfonyl semicarbazide, barium azodicarboxylate, 5-phenyltetrazole, trihydrazinotriazine, 4-toluenesulfonyl azide, 4,4′-diphen
  • liquids such as liquid fluorocarbons and pentanes that are liquid at room temperature, and gaseous fluorocarbons, nitrogen, carbon dioxide, air, helium, argon, and the like that are gaseous or liquefied can be used.
  • the blending amount of the foaming agent in the resin composition is preferably 0.05 to 2 parts by mass and more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the polyamide resin.
  • the blending amount of the foaming agent is less than 0.05 parts by mass, the amount of gas to be foamed is small, the expansion ratio is not increased, the apparent overall density of the resulting foamed molded article is large, and the mass reduction effect cannot be obtained. There is.
  • the blending amount exceeds 2 parts by mass, the mechanical strength of the obtained foamed molded product may be lowered, or the surface appearance such as generation of silver streak or swirl mark may be impaired.
  • the foam molded article of the present invention is foam-molded by a conventional method using the resin composition and the foaming agent described above.
  • the foaming agent when the foaming agent is solid, the obtained resin composition is pelletized or powdered, mixed with the foaming agent, and then the mixture is fed into a molding machine, melted, and injection molded.
  • a foamed molded product can be obtained.
  • the foaming agent may be added directly, or may be added using a master batch pellet obtained by melt-kneading a thermoplastic resin and a foaming agent in advance. Moreover, you may use the masterbatch pellet which pressed the foaming nucleating agent, the binder, etc. with the foaming agent using the disk pelleter.
  • the foaming agent is a gas or liquid, as represented by mucell foaming, the foaming agent is directly added to the molten resin composition and uniformly dispersed, and foamed at the time of molding to obtain a foamed molded article.
  • the core layer in which the foamed cells exist is covered with a skin layer in which the foamed cells do not exist.
  • a foamed molded article is produced, for example, by injecting a molten foamable resin composition into a mold cavity in an injection molding machine, and when the molten resin reaches the vicinity of the flow end for 0.2 to 1.0 seconds.
  • An injection core back type injection molding method in which a holding pressure of 20 to 100 MPa is applied, and then the mold core portion adjacent to the mold cavity is retracted at a speed of 10 to 100 mm / sec in a direction in which the thickness of the middle mold cavity is expanded. Can be obtained at
  • the set foaming ratio (X) is obtained by the following formula from the retreat distance of the die plate and the initial depth of the mold cavity.
  • Set foaming ratio (X) (initial depth + retract distance of die plate) / (initial depth)
  • the actual expansion ratio (Y) of foaming at this time can be calculated as a ratio ( ⁇ 0 / ⁇ 1 ) between the density of the unfoamed body ( ⁇ 0 ) and the density of the foamed molded body ( ⁇ 1 ).
  • the actual expansion ratio is preferably 1.15 to 3.00, more preferably 1.25 to 2.60.
  • the foaming efficiency (Y / X) calculated from the set foaming ratio (X) and the actual foaming ratio (Y) is an index of surface smoothness, preferably 85% or more, and preferably 90% or more. It is more preferable that When the foaming efficiency (Y / X) is 85% or more, the foamed molded body that foams in the mold increases the adhesion to the mold, and the surface smoothness of the foamed molded body is improved.
  • the foamed molded article of the present invention has a good surface appearance and excellent impact resistance, it can be suitably used in applications such as the electric / electronic equipment field, the automobile field, and the machine field.
  • the fiber diameter of 10 cellulose fibers was measured, and the average value of 10 fibers was calculated as the average fiber diameter.
  • a 10 ⁇ m section was cut out with a microtome, or the foamed molded product was observed as it was using a stereomicroscope (OLYMPUS SZ-40). The fiber diameter was measured in the same manner as described above from the obtained image, and the average fiber diameter was determined.
  • the line segment of the maximum length is calculated
  • the length is set to P,
  • the line segment The cell length in a direction passing through the midpoint and perpendicular to the line segment was determined, the length was defined as Q, and (P + Q) / 2 was defined as the cell diameter.
  • the cell diameter was measured for the foamed cell considered to be the maximum, and this was taken as the maximum cell diameter.
  • the measurement surface was divided into 6 equal parts by 5 line segments parallel to the thickness direction, and the cell diameter was measured for 10 foam cells existing near the midpoint of each line segment, for a total of 50 cells.
  • the average value of the cell diameter was calculated and used as the average cell diameter (b).
  • Example 1 As an aqueous dispersion of cellulose fibers, serisch KY100G (manufactured by Daicel Finechem Co., Ltd .: containing 10% by mass of cellulose fibers having an average fiber diameter of 125 nm) was added to this, and purified water was added thereto, followed by stirring with a mixer. An aqueous dispersion having a fiber content of 3% by mass was prepared. 70 parts by mass of this aqueous dispersion of cellulose fibers and 100 parts by mass of ⁇ -caprolactam were further stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion was heated to 240 ° C.
  • the resin composition was manufactured by dry blending with the black pigment mixture. Core back injection molding was performed using the obtained resin composition.
  • the resin composition was put into an injection molding machine (S-2000i manufactured by FANUC) equipped with a shut-off nozzle, and a mold finished with a mirror finish under conditions of a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. Injection molded.
  • the test piece was filled in 0.2 seconds to the flow end and then subjected to a pressure holding process at 75 MPa for 0.5 seconds.
  • the die plate of the injection molding machine was set at 60 mm / second. It was made to recede so as to be 5 times to obtain a mirror-finished foamed molded article composed of a core layer and a skin layer.
  • injection molding was performed under the same conditions as above to obtain a textured foamed molded article.
  • Production Example 1 Production of bacterial cellulose 50 ml of a medium composed of 0.5 mass% glucose, 0.5 mass% polypeptone, 0.5 mass% yeast extract and 0.1 mass% magnesium sulfate heptahydrate was added to 200 ml. The solution was dispensed into a conical flask and steam sterilized at 120 ° C. for 20 minutes in an autoclave. One platinum ear of Gluconacetobacter xylinus (NBRC 16670) grown on a test tube slant agar medium was inoculated, and left to stand at 30 ° C. for 7 days. Seven days later, a white gel film-like bacterial cellulose was formed in the upper layer of the culture solution.
  • NBRC 16670 Gluconacetobacter xylinus
  • Example 2 The bacterial cellulose obtained in Production Example 1 was used as the cellulose fiber. Bacterial cellulose was crushed with a mixer, and then water substitution was performed by repeating immersion and washing with water. 35 parts by mass of an aqueous dispersion of bacterial cellulose after water replacement (containing 6.5% by mass of bacterial cellulose having an average fiber diameter of 60 nm), 194 parts by mass of ⁇ -caprolactam, 40 parts by mass of aminocaproic acid, 90 parts by mass of purified water was stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C.
  • Example 1 The resin composition A containing this was obtained.
  • the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
  • Example 3 Purified water was added to the aggregate of cellulose fibers produced as waste yarn in the nonwoven fabric manufacturing process, and the mixture was stirred with a mixer to prepare an aqueous dispersion containing 3% by mass of cellulose fibers having an average fiber diameter of 120 nm. 170 parts by mass of this aqueous dispersion of cellulose fibers, 216 parts by mass of ⁇ -caprolactam, and 44 parts by mass of aminocaproic acid were stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C.
  • Example 5 The cellulose fiber content is the same as in Example 1 except that serisch KY110N (manufactured by Daicel Finechem Co., Ltd .: cellulose fiber having an average fiber diameter of 150 nm) is used as the aqueous dispersion of cellulose fibers.
  • a cellulose aqueous dispersion was prepared so as to be 3% by mass. 70 parts by mass of this aqueous dispersion of cellulose fibers and 200 parts by mass of ⁇ -caprolactam were further stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor.
  • a polymerization reaction was carried out at 240 ° C. for 3 hours to obtain a resin composition A containing a polyamide resin and cellulose fibers.
  • eta relative viscosity
  • Example 9 The cellulose fiber content is the same as in Example 1 except that serisch KY100S (manufactured by Daicel Finechem: 25% by mass of cellulose fibers having an average fiber diameter of 180 nm) is used as the aqueous dispersion of cellulose fibers.
  • a cellulose aqueous dispersion was prepared so as to be 3% by mass, and polymerization was performed in the same manner as in Example 1 to obtain pellets of the resin composition A.
  • Example 10 Celish KY100S was used as an aqueous dispersion of cellulose fibers. 49 parts by mass of this cellulose fiber aqueous dispersion, 216 parts by mass of ⁇ -caprolactam, 44 parts by mass of aminocaproic acid, and 157 parts by mass of purified water were stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C. for 1 hour to perform a polymerization reaction. The resin composition A containing this was obtained.
  • the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
  • Example 13 As an aqueous dispersion of cellulose fiber, purified water was added to SERISH KY100G and stirred with a mixer to prepare a cellulose fiber content of 3% by mass. 170 parts by mass of an aqueous dispersion of this cellulose fiber, 254 parts by mass of ⁇ -caprolactam, 2.5 parts by mass of swellable fluorinated mica as a layered silicate (manufactured by Corp Chemical Chemical Co., Ltd .: ME-100), phosphorous acid 0.25 parts by mass (0.14 mol% based on ⁇ -caprolactam) was stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed solution was heated to 240 ° C.
  • Comparative Example 2 Except having used the cotton short fiber (average fiber diameter of 16 micrometers) as a cellulose fiber, it carried out similarly to Example 1, and obtained the pellet of the resin composition A containing a polyamide resin and a cellulose fiber.
  • Comparative Example 3 As cellulose fiber, serisch KY100S was freeze-dried and then pulverized to prepare a powder.
  • a twin screw extruder having a screw diameter of 30 mm and an average groove depth of 2.5 mm is blended with 100 parts by mass of nylon 6 (BRL number average molecular weight 17000 manufactured by Unitika Ltd.) and 2 parts by mass of the obtained powdery cellulose. (PCM-30 manufactured by Ikegai Co., Ltd.) and melt kneaded at a barrel temperature of 240 ° C., a screw rotation speed of 120 rpm, and a residence time of 2.7 minutes. The melt-kneaded product was discharged, cut into pellets, and the resulting pellets were dried.
  • PCM-30 manufactured by Ikegai Co., Ltd.
  • Comparative Example 4 Resin composition A pellets were obtained in the same manner as in Example 10 except that the polymerization reaction was carried out so that the cellulose fiber content was as shown in Table 1.
  • Comparative Example 7 254 parts by mass of ⁇ -caprolactam, 10.2 parts by mass of layered silicate (swelling fluorinated mica) and 0.25 parts by mass of phosphorous acid (0.14 mol% with respect to ⁇ -caprolactam) were heated to 80 ° C. The mixture was stirred and mixed with a homogenizer until a uniform solution was obtained while heating. Subsequently, the mixed solution was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was performed at 240 ° C.
  • a resin composition B containing a polyamide resin and a layered silicate.
  • the resin composition B was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
  • Table 1 shows the measurement results of the characteristic values of the foam molded articles obtained in Examples 1 to 13 and Comparative Examples 1 to 7. In the measurement of the characteristic value of the foam, a mirror-finished foam was used except for the appearance evaluation.
  • Examples 1 to 13 as described above, an aqueous dispersion of cellulose fibers having an average fiber diameter of 10 ⁇ m or less and a monomer constituting the polyamide resin are mixed, and the polymerization reaction of the monomer is performed, whereby the polyamide resin is mixed.
  • a fine cellulose fiber was uniformly dispersed without agglomeration, and a resin composition obtained by adding a foam nucleating agent thereto was injection molded by the core back method to obtain a foam molded article. Therefore, the foam molded articles obtained in Examples 1 to 13 are composed of a core layer and a skin layer, and the core layer has foam cells.
  • the obtained foamed molded article has a maximum cell diameter of 0.8 mm or less, a uniformity of 0.5 mm or less, a particularly large size and a large amount of fine foam cells, and a surface appearance.
  • the impact resistance was very good.
  • Comparative Example 1 since the resin composition did not contain cellulose fibers, the foaming ratio was low and it was difficult to foam, and the obtained foamed molded article had large foam cells and was not uniform. there were.
  • Comparative Example 2 since the resin composition contained cellulose fibers having an average fiber diameter exceeding 10 ⁇ m, the obtained foamed molded article was foam-molded in Example 1 in which the content of cellulose fibers was the same. Compared with the body, the foam cells are large and uneven, cellulose aggregates are observed, silver streaks, swirl marks, sink marks, etc. are confirmed, the surface appearance is inferior, and the impact resistance is also inferior. It was.
  • Comparative Example 3 since the polyamide resin and the cellulose fiber were melt-kneaded, the dispersibility of the cellulose fiber was low, and the resin composition was able to visually confirm the aggregation of the cellulose fiber, and contained a cellulose fiber having a large average fiber diameter. It was a thing.
  • the foamed molded product obtained from this resin composition has a large and non-uniform foamed cell as compared with the foamed molded product of Example 9 in which the type and content of cellulose fibers are the same, and the surface appearance is inferior. It was also inferior in impact resistance.
  • Comparative Example 4 since the resin composition contained excessive cellulose fibers, the obtained foamed molded article had a small number of foam cells and a small average cell diameter.

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Abstract

　A molded foam characterized in comprising a resin composition containing 0.1 to 10 mass parts of a cellulose fiber having an average fiber diameter of 10 μm or less and 0.01 to 15 mass parts of a foam nucleating agent in relation to 100 mass parts of a polyamide resin, and in having foam cells.

Description

発泡成形体Foam molding
　本発明は、ポリアミド樹脂を用いた樹脂組成物からなり、表面外観が良好で、耐衝撃性に優れた発泡成形体に関するものである。 The present invention relates to a foam molded article comprising a resin composition using a polyamide resin, having a good surface appearance and excellent impact resistance.
　ポリアミド樹脂は、機械的特性、耐薬品性、耐熱性、成形加工性などの特性に優れており、その成形体は、従来から自動車部品、電子電機部品などに広く利用されている。 Polyamide resin is excellent in properties such as mechanical properties, chemical resistance, heat resistance, and moldability, and the molded body has been widely used for automobile parts, electronic parts and the like.
　また、ポリアミド樹脂に、ガラス繊維、炭素繊維、タルク、クレイなどの無機充填剤を配合して強化した樹脂組成物を用いて、多くの成形体が成形されている。しかしこれらの強化材は、多量に配合しないと成形体の機械的特性や熱的特性が改善しないという問題点や、比重が高いために、得られる成形体の質量が大きくなるという問題点があった。
　また、強化材としてガラス繊維、炭素繊維等を用いた場合、得られた成形体は、そりが大きくなるという問題点があった。また、強化材としてタルク、クレイ等を用いた場合は、得られた成形体を廃棄する際、これら強化材は、焼却残渣として残存するため、土中に埋設処理され、半永久的に地中に残留するという問題点があった。 In addition, many molded articles are molded using a resin composition reinforced by blending polyamide resin with an inorganic filler such as glass fiber, carbon fiber, talc, or clay. However, these reinforcing materials have a problem that the mechanical properties and thermal properties of the molded body cannot be improved unless they are blended in a large amount, and the mass of the resulting molded body increases due to its high specific gravity. It was.
Further, when glass fiber, carbon fiber or the like is used as the reinforcing material, the obtained molded product has a problem that warpage becomes large. In addition, when talc, clay, etc. are used as reinforcing materials, when the obtained molded product is discarded, these reinforcing materials remain as incineration residues, so they are buried in the soil and semi-permanently in the ground. There was a problem of remaining.
　近年、樹脂材料の強化材としてセルロースが用いられている。セルロースには、樹木から得られるものや、稲、綿、ケナフ、麻などの非木材資源から得られるものや、微生物が生産するバクテリアセルロースなどがあり、セルロースは地球上に非常に多量に存在する。セルロースは機械的特性に優れており、これを樹脂中に含有させることにより、樹脂組成物の特性、すなわち成形体の特性を向上させる効果が期待される。 In recent years, cellulose has been used as a reinforcing material for resin materials. Cellulose includes those obtained from trees, those obtained from non-wood resources such as rice, cotton, kenaf and hemp, and bacterial cellulose produced by microorganisms. Cellulose is present in large quantities on the earth. . Cellulose is excellent in mechanical properties. By containing this in the resin, an effect of improving the properties of the resin composition, that is, the properties of the molded product is expected.
　一方、上記したようなポリアミド樹脂の特性を活かしながら、軽量化を図った成形体として、ポリアミド樹脂に発泡剤を添加して発泡成形してなる発泡成形体が提案されている。 On the other hand, a foamed molded product obtained by foaming by adding a foaming agent to a polyamide resin has been proposed as a molded product that is reduced in weight while utilizing the characteristics of the polyamide resin as described above.
　例えば、特許文献１には、熱可塑性樹脂とセルロース繊維を含有する熱可塑性樹脂組成物からなり、発泡構造を有する熱可塑性樹脂成形体が開示されており、熱可塑性樹脂としてポリアミド樹脂も記載されている。この発明においては、熱可塑性樹脂とセルロース繊維とを混合するために、２軸高混練型押出機が使用されている。
　熱可塑性樹脂中にセルロースを含有させる方法としては、樹脂とセルロース繊維とを溶融混合する方法が一般的である。しかしながら、この方法では、セルロース繊維は、凝集した状態のまま樹脂中に混合されるため、均一に分散されておらず、また、セルロース繊維の平均繊維径は大きいものであった。
　また、特許文献１は、木肌に似た肌触り性を有する成形体を得ることを目的としており、この目的を達成するために、セルロース繊維を多く含有させて、成形体の表面粗さを高いものとしている。
　したがって特許文献１に記載の発泡成形体は、大きさが均一でかつ細かい発泡セルが多量に存在するものではなく、よって発泡成形体は、表面外観に劣り、耐衝撃性も低いものとなっていた。 For example, Patent Document 1 discloses a thermoplastic resin molded article having a foam structure, which is made of a thermoplastic resin composition containing a thermoplastic resin and cellulose fibers, and also describes a polyamide resin as the thermoplastic resin. Yes. In this invention, in order to mix a thermoplastic resin and a cellulose fiber, the biaxial high kneading type | mold extruder is used.
As a method of incorporating cellulose into the thermoplastic resin, a method of melt-mixing the resin and cellulose fiber is common. However, in this method, since the cellulose fibers are mixed in the resin in an aggregated state, they are not uniformly dispersed, and the average fiber diameter of the cellulose fibers is large.
Patent Document 1 is intended to obtain a molded article having a touch similar to that of a wooden surface, and in order to achieve this object, a large amount of cellulose fibers are contained to increase the surface roughness of the molded article. It is said.
Therefore, the foam molded article described in Patent Document 1 does not have a large amount of foam cells that are uniform in size and fine, and therefore the foam molded article is inferior in surface appearance and has low impact resistance. It was.
特開２００７－８４６９８号公報JP 2007-84698 A
　本発明は、上記の問題点を解決するものであり、ポリアミド樹脂とセルロース繊維を含有する樹脂組成物からなる発泡成形体であって、大きさが均一でかつ細かい発泡セルを多量に有し、表面外観が良好で、耐衝撃性にも優れる発泡成形体を提供することを目的とするものである。 The present invention solves the above problems, and is a foamed molded article comprising a resin composition containing a polyamide resin and cellulose fibers, and has a large amount of foam cells that are uniform in size and fine, An object of the present invention is to provide a foam molded article having a good surface appearance and excellent impact resistance.
　本発明者らは、前記課題を解決するために鋭意研究を重ねた結果、本発明に到達した。
　すなわち、本発明の要旨は、下記の通りである。
（１）ポリアミド樹脂１００質量部に対して、平均繊維径が１０μｍ以下のセルロース繊維を０．１～１０質量部、発泡核剤を０．０１～１５質量部含有する樹脂組成物から構成され、発泡セルを有することを特徴とする発泡成形体。
（２）発泡成形体がコア層とスキン層とから構成され、コア層が発泡セルを有することを特徴とする（１）記載の発泡成形体。
（３）発泡セルの最大セル径が２ｍｍ以下であることを特徴とする（１）または（２）記載の発泡成形体。
（４）樹脂組成物を構成するポリアミド樹脂とセルロース繊維とが、水を含んだ状態のセルロース繊維の存在下に、ポリアミド樹脂を構成するモノマーの重合反応を行うことにより得られたものであることを特徴とする（１）～（３）のいずれかに記載の発泡成形体。
（５）樹脂組成物をコアバック射出成形法により成形したものであることを特徴とする（１）～（４）のいずれかに記載の発泡成形体。 The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.
That is, the gist of the present invention is as follows.
(1) A resin composition comprising 0.1 to 10 parts by mass of cellulose fibers having an average fiber diameter of 10 μm or less and 0.01 to 15 parts by mass of a foam nucleating agent with respect to 100 parts by mass of a polyamide resin, A foamed molded article having a foamed cell.
(2) The foamed molded article according to (1), wherein the foamed molded article comprises a core layer and a skin layer, and the core layer has foamed cells.
(3) The foamed molded article according to (1) or (2), wherein the foamed cell has a maximum cell diameter of 2 mm or less.
(4) The polyamide resin and the cellulose fiber constituting the resin composition are obtained by performing a polymerization reaction of the monomer constituting the polyamide resin in the presence of the cellulose fiber containing water. The foamed molded article according to any one of (1) to (3), wherein
(5) The foamed molded article according to any one of (1) to (4), wherein the resin composition is molded by a core back injection molding method.
　本発明の発泡成形体は、平均繊維径が小さいセルロース繊維と発泡核剤とを特定量含有する樹脂組成物を発泡させることにより得られるものであるため、大きさが均一でかつ細かい発泡セルを多量に有するものとなる。このため、本発明の発泡成形体は表面外観に優れるとともに、耐衝撃性にも優れたものとなる。
　また、平均繊維径が小さいセルロース繊維と発泡核剤とを特定量含有する樹脂組成物を用いることで、コアバック射出成形法により、成形加工を行うことができ、コア層とスキン層を有する発泡成形体とすることができる。そして、このような本発明の発泡成形体は、スワールマーク（成形体表面に生じる破泡痕）やシルバーストリークス（成形体表面に樹脂の流動方向に沿って生成する銀条痕）やヒケ（成形体表面に生じる凹み）等が生じることのない、表面外観に優れるものとなる。 The foamed molded article of the present invention is obtained by foaming a resin composition containing a specific amount of cellulose fibers having a small average fiber diameter and a foam nucleating agent. It will have a large amount. For this reason, the foamed molded article of the present invention has excellent surface appearance and excellent impact resistance.
In addition, by using a resin composition containing a specific amount of cellulose fibers having a small average fiber diameter and a foam nucleating agent, molding processing can be performed by a core back injection molding method, and foam having a core layer and a skin layer. It can be set as a molded body. And such a foaming molding of the present invention includes swirl marks (foam marks generated on the surface of the molding), silver streaks (silver marks generated along the flow direction of the resin on the molding surface), sink marks ( It is excellent in surface appearance without causing a dent or the like on the surface of the molded body.
　以下、本発明を詳細に説明する。
　本発明の発泡成形体は、ポリアミド樹脂、平均繊維径が１０μｍ以下であるセルロース繊維及び発泡核剤を含有する樹脂組成物から構成され、発泡セルを有するものである。 Hereinafter, the present invention will be described in detail.
The foamed molded article of the present invention comprises a resin composition containing a polyamide resin, cellulose fibers having an average fiber diameter of 10 μm or less, and a foam nucleating agent, and has foam cells.
＜ポリアミド樹脂＞
　本発明で用いるポリアミド樹脂は、アミノ酸、ラクタムあるいはジアミンとジカルボン酸とから形成されるアミド結合を有する重合体をいうものである。 <Polyamide resin>
The polyamide resin used in the present invention refers to a polymer having an amide bond formed from an amino acid, lactam or diamine and a dicarboxylic acid.
　このようなポリアミド樹脂を形成するモノマーの例として、アミノ酸としては、６－アミノカプロン酸、１１－アミノウンデカン酸、１２－アミノドデカン酸、パラアミノメチル安息香酸などが挙げられる。
　ラクタムとしては、ε－カプロラクタム、ω－ラウロラクタムなどが挙げられる。 Examples of monomers that form such a polyamide resin include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and paraaminomethylbenzoic acid.
Examples of the lactam include ε-caprolactam and ω-laurolactam.
　ジアミンとしては、テトラメチレンジアミン、ヘキサメチレンジアミン、ノナメチレンジアミン、デカメチレンジアミン、ウンデカメチレンジアミン、ドデカメチレンジアミン、２，２，４－／２，４，４－トリメチルヘキサメチレンジアミン、５－メチルノナメチレンジアミン、２，４－ジメチルオクタメチレンジアミン、メタキシリレンジアミン、パラキシリレンジアミン、１，３－ビス（アミノメチル）シクロヘキサン、１－アミノ－３－アミノメチル－３，５，５－トリメチルシクロヘキサン、３，８－ビス（アミノメチル）トリシクロデカン、ビス（４－アミノシクロヘキシル）メタン、ビス（３－メチル－４－アミノシクロヘキシル）メタン、２，２－ビス（４－アミノシクロヘキシル）プロパン、ビス（アミノプロピル）ピペラジン、アミノエチルピペラジンなどが挙げられる。
　ジカルボン酸としてはアジピン酸、スベリン酸、アゼライン酸、セバシン酸、ドデカン二酸、テレフタル酸、イソフタル酸、ナフタレンジカルボン酸、２－クロロテレフタル酸、２－メチルテレフタル酸、５－メチルイソフタル酸、５－ナトリウムスルホイソフタル酸、ヘキサヒドロテレフタル酸、ヘキサヒドロイソフタル酸、ジグリコール酸などが挙げられる。 Examples of diamines include tetramethylene diamine, hexamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,4- / 2,4,4-trimethylhexamethylene diamine, and 5-methyl. Nonamethylenediamine, 2,4-dimethyloctamethylenediamine, metaxylylenediamine, paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethyl Cyclohexane, 3,8-bis (aminomethyl) tricyclodecane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, Bis (aminopropyl) pipette Jin, and an amino ethyl piperazine.
Dicarboxylic acids include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5- Examples include sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and diglycolic acid.
　より具体的には、本発明で用いるポリアミド樹脂としては、ポリカプロアミド（ナイロン６）、ポリテトラメチレンアジパミド（ナイロン４６）、ポリヘキサメチレンアジパミド（ナイロン６６）、ポリヘキサメチレンセバカミド（ナイロン６１０）、ポリヘキサメチレンドデカミド（ナイロン６１２）、ポリウンデカメチレンアジパミド（ナイロン１１６）、ポリウンデカンアミド（ナイロン１１）、ポリドデカンアミド（ナイロン１２）、ポリトリメチルヘキサメチレンテレフタルアミド（ナイロンＴＭＨＴ）、ポリヘキサメチレンテレフタルアミド（ナイロン６Ｔ）、ポリヘキサメチレンイソフタルアミド（ナイロン６Ｉ）、ポリヘキサメチレンテレフタル／イソフタルアミド（ナイロン６Ｔ／６Ｉ）、ポリビス（４－アミノシクロヘキシル）メタンドデカミド（ナイロンＰＡＣＭ１２）、ポリビス（３－メチル－４－アミノシクロヘキシル）メタンドデカミド（ナイロンジメチルＰＡＣＭ１２）、ポリメタキシリレンアジパミド（ナイロンＭＸＤ６）、ポリノナメチレンテレフタルアミド（ナイロン９Ｔ）、ポリデカメチレンテレフタルアミド（ナイロン１０Ｔ）、ポリウンデカメチレンテレフタルアミド（ナイロン１１Ｔ）、ポリウンデカメチレンヘキサヒドロテレフタルアミド（ナイロン１１Ｔ（Ｈ））が挙げられ、これらの共重合体や混合物であってもよい。中でも特に好ましいポリアミド樹脂は、ナイロン６、ナイロン６６、ナイロン１１、ナイロン１２、およびこれらの共重合体や混合物である。 More specifically, the polyamide resin used in the present invention includes polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebaca. Mido (nylon 610), polyhexamethylene dodecane (nylon 612), polyundecane methylene adipamide (nylon 116), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polytrimethylhexamethylene terephthalamide (Nylon TMHT), polyhexamethylene terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide / isophthalamide (nylon 6T / 6I), polybis (4-aminocyclo) Xyl) methane dodecamide (nylon PACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (nylon dimethyl PACM12), polymetaxylylene adipamide (nylon MXD6), polynonamethylene terephthalamide (nylon 9T) , Polydecamethylene terephthalamide (nylon 10T), polyundecamethylene terephthalamide (nylon 11T), polyundecamethylene hexahydroterephthalamide (nylon 11T (H)), and these copolymers and mixtures. May be. Among them, particularly preferred polyamide resins are nylon 6, nylon 66, nylon 11, nylon 12, and copolymers and mixtures thereof.
　上記ポリアミド樹脂は、後述する重合法で、あるいはさらに固相重合法を併用して製造される。 The above polyamide resin is produced by a polymerization method described later, or by further using a solid phase polymerization method.
＜セルロース繊維＞
　次に、本発明で用いるセルロース繊維としては、木材、稲、綿、麻、ケナフなどに由来するものの他にバクテリアセルロース、バロニアセルロース、ホヤセルロースなど生物由来のものも含まれる。また、再生セルロース、セルロース誘導体なども含まれる。 <Cellulose fiber>
Next, the cellulose fibers used in the present invention include those derived from wood, rice, cotton, hemp, kenaf and the like, as well as those derived from organisms such as bacterial cellulose, valonia cellulose and squirt cellulose. Also included are regenerated cellulose, cellulose derivatives and the like.
　本発明において、大きさが均一でかつ細かい発泡セルを多量に有する発泡成形体とするには、セルロース繊維を凝集させることなく、樹脂中に均一に分散させることが必要である。そのためにはポリアミド樹脂に対するセルロース繊維の分散性や、ポリアミド樹脂とセルロース繊維の親和性が重要である。また、セルロース繊維が有する水酸基などの性質をできるだけ発揮させるためには、セルロース繊維の表面積を増やすことが重要である。このため、できるだけ微細化されたセルロース繊維を使用することが必要となる。 In the present invention, in order to obtain a foam-molded product having a large size and a large number of fine foam cells, it is necessary to uniformly disperse the cellulose fibers in the resin without aggregating them. For that purpose, the dispersibility of the cellulose fiber to the polyamide resin and the affinity between the polyamide resin and the cellulose fiber are important. Further, in order to make the cellulose fiber have properties such as hydroxyl groups as much as possible, it is important to increase the surface area of the cellulose fiber. For this reason, it is necessary to use as fine a cellulose fiber as possible.
　したがって、本発明における樹脂組成物中に含有されるセルロース繊維は、平均繊維径が１０μｍ以下であることが必要であり、中でも平均繊維径は１μｍ以下であることが好ましく、５００ｎｍ以下であることがより好ましく、さらには、３００ｎｍ以下であることが好ましく、最も好ましくは４０～１００ｎｍである。
　樹脂組成物中に含有されるセルロース繊維の平均繊維径が１０μｍを超える場合、セルロース繊維の表面積を増やすことができず、ポリアミド樹脂に対する分散性や親和性を向上させることが困難となる。このため、得られる発泡成形体は、発泡セルの大きさが均一にならず、また発泡セルが大きくなり、またセルロース繊維が目視で確認されるので、表面外観、耐衝撃性に劣るものとなる。 Therefore, the cellulose fiber contained in the resin composition in the present invention needs to have an average fiber diameter of 10 μm or less, and the average fiber diameter is preferably 1 μm or less, and preferably 500 nm or less. More preferably, it is preferably 300 nm or less, and most preferably 40 to 100 nm.
When the average fiber diameter of the cellulose fibers contained in the resin composition exceeds 10 μm, the surface area of the cellulose fibers cannot be increased, and it becomes difficult to improve the dispersibility and affinity for the polyamide resin. For this reason, the foamed molded article obtained does not have uniform foam cell size, the foam cell becomes large, and the cellulose fibers are visually confirmed, resulting in poor surface appearance and impact resistance. .
　樹脂組成物中のセルロース繊維の平均繊維径を１０μｍ以下とするには、平均繊維径が１０μｍ以下のセルロース繊維を用いることが必要である。このようなセルロース繊維としては、セルロース繊維を引き裂くことによってミクロフィブリル化したものが好ましい。ミクロフィブリル化する手段としては、ボールミル、石臼粉砕機、高圧ホモジナイザー、ミキサーなど各種粉砕装置を使用することができる。また、セルロース繊維として、市販されているものとして、例えば、ダイセルファインケム社製の「セリッシュ」を用いることができる。 In order to make the average fiber diameter of the cellulose fibers in the resin composition 10 μm or less, it is necessary to use cellulose fibers having an average fiber diameter of 10 μm or less. As such a cellulose fiber, what was microfibrillated by tearing a cellulose fiber is preferable. Various pulverizing apparatuses such as a ball mill, a stone mill, a high-pressure homogenizer, and a mixer can be used as means for microfibrillation. Moreover, as a cellulose fiber, what is marketed can use "Serish" by Daicel FineChem, for example.
　また、平均繊維径が１０μｍ以下のセルロース繊維として、セルロース繊維を使用した繊維製品の製造工程において、屑糸として出されたセルロース繊維の集合体を使用することもできる。繊維製品の製造工程とは紡績時、織布時、不織布製造時、そのほか繊維製品の加工時などが挙げられる。これらのセルロース繊維の集合体は、セルロース繊維がこれらの工程を経た後に屑糸となったものであるため、セルロース繊維が微細化したものとなっている。 Moreover, in the manufacturing process of a fiber product using cellulose fibers as cellulose fibers having an average fiber diameter of 10 μm or less, an aggregate of cellulose fibers taken out as scrap yarn can be used. The production process of the textile product includes spinning, woven fabric, nonwoven fabric production, and other textile product processing. Since these cellulose fiber aggregates are scrap fibers after the cellulose fibers have undergone these steps, the cellulose fibers are refined.
　また、セルロース繊維として、バクテリアが産出するバクテリアセルロースを使用することもでき、例えば、アセトバクター族の酢酸菌を生産菌として産出されたものを使用することができる。植物のセルロースは、セルロースの分子鎖が収束したもので、非常に細いミクロフィブリルが束になって形成されているものであるのに対し、酢酸菌より産出されたセルロースはもともと幅２０～５０ｎｍのリボン状であり、植物のセルロースと比較すると極めて細い網目状を形成している。 In addition, bacterial cellulose produced by bacteria can be used as the cellulose fiber, and for example, those produced using an Acetobacter acetic acid bacterium as a producing bacterium can be used. Plant cellulose is composed of cellulose molecular chains converged and formed by bundles of very thin microfibrils, whereas cellulose produced from acetic acid bacteria originally has a width of 20-50 nm. It is in the form of a ribbon, and forms an extremely fine network compared to plant cellulose.
　また、セルロース繊維として、Ｎ－オキシル化合物の存在下にセルロース繊維を酸化させた後に、水洗、物理的解繊工程を経ることにより得られる、微細化されたセルロース繊維を使用してもよい。
　Ｎ－オキシル化合物としては各種あるが、たとえば、Ｃｅｌｌｕｌｏｓｅ（１９９８）５，１５３－１６４に記載されているような２，２，６，６－Ｔｅｔｒａｍｅｔｈｙｌｐｉｐｅｒｉｄｉｎｅ－１－ｏｘｙｌ　ｒａｄｉｃａｌ（以下ＴＥＭＰＯと記す）などが好ましい。このような化合物を触媒量の範囲で反応水溶液に添加する。
　この水溶液に共酸化剤として次亜塩素酸ナトリウムや亜塩素酸ナトリウムを加え、臭化アルカリ金属を加えることにより反応を進行させる。水酸化ナトリウム水溶液などのアルカリ性の化合物を添加してｐＨを１０付近に保持し、ｐＨの変化が見られなくなるまで反応を継続する。反応温度は室温で構わない。反応後、系内に残存するＮ－オキシル化合物を除去することが好ましい。洗浄はろ過、遠心分離など各種方法を採用することができる。
　その後、上記したような各種粉砕装置を用い、物理的な解繊工程を経ることで微細化されたセルロース繊維を得ることができる。 Further, as the cellulose fiber, a refined cellulose fiber obtained by oxidizing the cellulose fiber in the presence of an N-oxyl compound, followed by washing with water and physical defibrating may be used.
There are various types of N-oxyl compounds, such as 2,2,6,6-tetramethylpiperidine-1-oxyl radical (hereinafter referred to as TEMPO) as described in Cellulose (1998) 5,153-164. preferable. Such a compound is added to the reaction aqueous solution in a catalytic amount range.
To this aqueous solution, sodium hypochlorite or sodium chlorite is added as a co-oxidant, and the reaction is allowed to proceed by adding an alkali metal bromide. An alkaline compound such as an aqueous sodium hydroxide solution is added to maintain the pH at around 10, and the reaction is continued until no change in pH is observed. The reaction temperature may be room temperature. After the reaction, it is preferable to remove the N-oxyl compound remaining in the system. Various methods such as filtration and centrifugation can be employed for washing.
Then, using various pulverizers as described above, it is possible to obtain refined cellulose fibers through a physical defibrating process.
　本発明における樹脂組成物中のセルロース繊維は、平均繊維径と平均繊維長との比であるアスペクト比（平均繊維長／平均繊維径）が１０以上であることが好ましく、中でも５０以上、さらには１００以上であることが好ましい。アスペクト比が１０以上であることにより、得られる発泡成形体の機械的特性が向上しやすくなる。 The cellulose fiber in the resin composition in the present invention preferably has an aspect ratio (average fiber length / average fiber diameter) which is a ratio of an average fiber diameter to an average fiber length of 10 or more, and more preferably 50 or more. It is preferable that it is 100 or more. When the aspect ratio is 10 or more, the mechanical properties of the obtained foamed molded product are easily improved.
　そして、本発明の発泡成形体を構成する樹脂組成物中のセルロース繊維の含有量は、ポリアミド樹脂１００質量部に対して、０．１～１０質量部であることが必要であり、中でも０．５～１０質量部であることが好ましく、さらには０．５～５質量部であることが好ましい。
　セルロース繊維の含有量がポリアミド樹脂１００質量部に対して０．１質量部未満である場合は、発泡成形において発泡しがたくなるため、大きさが均一でかつ細かい発泡セルを多量に有する発泡成形体を得ることができず、表面外観に劣り、また設定発泡倍率よりも低いものとなる。
　一方、セルロース繊維の含有量がポリアミド樹脂１００質量部に対して１０質量部を超える場合は、セルロース繊維（Ａ）を樹脂組成物中に含有させることが困難となったり、得られる発泡成形体は、セル径の大きな発泡セルが生じやすくなり、発泡セルの大きさが均一にならず、表面外観や耐衝撃性に劣るものとなる。 The content of the cellulose fiber in the resin composition constituting the foamed molded article of the present invention needs to be 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin. The amount is preferably 5 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass.
When the cellulose fiber content is less than 0.1 parts by mass with respect to 100 parts by mass of the polyamide resin, foaming is difficult to foam in foam molding, so foam molding having a large amount of uniform and fine foam cells. A body cannot be obtained, the surface appearance is inferior, and the foaming ratio is lower than the set expansion ratio.
On the other hand, when the content of the cellulose fiber exceeds 10 parts by mass with respect to 100 parts by mass of the polyamide resin, it becomes difficult to contain the cellulose fiber (A) in the resin composition, or the obtained foamed molded article is A foam cell having a large cell diameter is likely to be generated, the size of the foam cell is not uniform, and the surface appearance and impact resistance are poor.
　中でも、本発明における樹脂組成物を、後述するような製造法で得ることにより、セルロース繊維の含有量が少量であっても、それがポリアミド樹脂中に均一に分散された樹脂組成物となるので、発泡成形において、十分に発泡し、かつ大きさが均一でかつ細かい発泡セルを多量に有する発泡成形体を得ることが可能となる。さらには、得られた発泡成形体の耐衝撃性を高いものとすることが可能となる。 Among them, by obtaining the resin composition in the present invention by a production method as described later, even if the cellulose fiber content is small, it becomes a resin composition uniformly dispersed in the polyamide resin. In foam molding, it is possible to obtain a foam molded article that is sufficiently foamed, has a uniform size, and has a large amount of fine foam cells. Furthermore, the impact resistance of the obtained foamed molded product can be increased.
　セルロース繊維は水との親和性が非常に高く、平均繊維径が小さいほど水に対して良好な分散状態を保つことができる。また、水を失うと水素結合により強固にセルロース繊維同士が凝集し、一旦凝集すると凝集前と同様の分散状態をとることが困難となる。特にセルロース繊維の平均繊維径が小さくなるほどこの傾向が顕著となる。
　したがって、セルロース繊維は水を含んだ状態でポリアミド樹脂と複合化することが好ましい。
　そこで、本発明においては、ポリアミド樹脂の重合時に、水を含んだ状態のセルロース繊維の存在下に、ポリアミド樹脂を構成するモノマーの重合反応を行うことにより、セルロース繊維を含有するポリアミド樹脂組成物を得る方法を採ることが好ましい。このような製造法により、ポリアミド樹脂中にセルロース繊維を凝集させずに均一に分散させることが可能となる。この製造法の詳細について次に述べる。 Cellulose fibers have a very high affinity with water, and the smaller the average fiber diameter, the better the dispersion state with respect to water. Further, when water is lost, cellulose fibers are strongly aggregated by hydrogen bonding, and once aggregated, it becomes difficult to achieve a dispersion state similar to that before aggregation. In particular, this tendency becomes more prominent as the average fiber diameter of the cellulose fibers decreases.
Therefore, the cellulose fiber is preferably combined with the polyamide resin in a state containing water.
Therefore, in the present invention, a polyamide resin composition containing cellulose fibers is obtained by performing a polymerization reaction of monomers constituting the polyamide resin in the presence of cellulose fibers containing water during the polymerization of the polyamide resin. It is preferable to take the method of obtaining. Such a production method makes it possible to uniformly disperse the cellulose fibers in the polyamide resin without aggregating them. Details of this manufacturing method will be described below.
＜セルロース繊維を含有するポリアミド樹脂組成物（樹脂組成物Ａ）＞
　本発明における樹脂組成物を製造するにあたり、予め、セルロース繊維を含有するポリアミド樹脂組成物（樹脂組成物Ａ）を調製しておくことが好ましい。すなわち、平均繊維径が１０μｍ以下であり、水を含んだ状態のセルロース繊維の存在下に、ポリアミド樹脂を構成するモノマーの重合反応を行うことにより、ポリアミド樹脂を得て、セルロース繊維を含有するポリアミド樹脂組成物（樹脂組成物Ａ）を調製しておくことが好ましい。たとえば、ポリアミド樹脂を構成するモノマーと、平均繊維径が１０μｍ以下のセルロース繊維の水分散液とを混合し、重合反応を行う。 <Polyamide resin composition containing cellulose fibers (resin composition A)>
In producing the resin composition in the present invention, it is preferable to prepare a polyamide resin composition (resin composition A) containing cellulose fibers in advance. That is, a polyamide resin having an average fiber diameter of 10 μm or less is obtained by conducting a polymerization reaction of monomers constituting the polyamide resin in the presence of water-containing cellulose fibers to obtain a polyamide resin. It is preferable to prepare a resin composition (resin composition A). For example, the monomer which comprises a polyamide resin and the aqueous dispersion of the cellulose fiber whose average fiber diameter is 10 micrometers or less are mixed, and a polymerization reaction is performed.
　この調製方法におけるセルロース繊維の水分散液は、平均繊維径が１０μｍ以下のセルロース繊維を水に分散させたものであり、水分散液中のセルロース繊維の含有量は０．０１～５０質量％とすることが好ましい。セルロース繊維の水分散液は、精製水とセルロース繊維とをミキサー等で攪拌することにより得ることができる。
　そして、セルロース繊維の水分散液と、ポリアミド樹脂を構成するモノマーとを混合し、ミキサー等で攪拌することにより均一な分散液とする。その後、分散液を加熱し、１５０～２７０℃まで昇温させて攪拌することにより重合反応させる。このとき、分散液を加熱する際に徐々に水蒸気を排出することにより、セルロース繊維の水分散液中の水分を排出することができる。なお、上記ポリアミド重合時においては、必要に応じてリン酸や亜リン酸などの触媒を添加してもよい。また、発泡核剤を上記ポリアミド重合時において添加してもよい。そして、重合反応終了後は、得られた樹脂組成物を払い出した後、切断してペレットとすることが好ましい。 The aqueous dispersion of cellulose fibers in this preparation method is obtained by dispersing cellulose fibers having an average fiber diameter of 10 μm or less in water, and the content of cellulose fibers in the aqueous dispersion is 0.01 to 50% by mass. It is preferable to do. The aqueous dispersion of cellulose fibers can be obtained by stirring purified water and cellulose fibers with a mixer or the like.
And the aqueous dispersion of a cellulose fiber and the monomer which comprises a polyamide resin are mixed, and it is set as a uniform dispersion by stirring with a mixer etc. Thereafter, the dispersion is heated, and the temperature is raised to 150 to 270 ° C., followed by stirring to cause a polymerization reaction. At this time, water in the aqueous dispersion of cellulose fibers can be discharged by gradually discharging water vapor when the dispersion is heated. In the polyamide polymerization, a catalyst such as phosphoric acid or phosphorous acid may be added as necessary. Further, a foam nucleating agent may be added during the polyamide polymerization. And after completion | finish of a polymerization reaction, after paying out the obtained resin composition, it is preferable to cut | disconnect and pelletize.
　また、セルロース繊維としてバクテリアセルロースを用いる場合においては、セルロース繊維の水分散液として、バクテリアセルロースを精製水に浸して溶媒置換したものを使用してもよい。バクテリアセルロースの溶媒置換したものを用いる際には、溶媒置換後、所定の濃度に調整した後、ポリアミド樹脂を構成するモノマーと混合し、上記と同様に重合反応を進行させることが好ましい。 When bacterial cellulose is used as the cellulose fiber, a cellulose fiber aqueous dispersion obtained by immersing bacterial cellulose in purified water and replacing the solvent may be used. When using a solvent-substituted bacterial cellulose, it is preferable to adjust the solvent concentration to a predetermined concentration and then mix with the monomer constituting the polyamide resin and proceed the polymerization reaction in the same manner as described above.
　このような調製方法では、平均繊維径が１０μｍ以下のセルロース繊維を用い、かつセルロース繊維を水分散液のまま重合反応に供することで、分散性が良好な状態で重合反応に供されることとなる。さらに、重合反応に供されたセルロース繊維は、重合反応中のモノマーや水との相互作用により、また上記のような温度条件で攪拌することにより、分散性が向上し、繊維同士が凝集することがなく、平均繊維径が小さいセルロース繊維が良好に分散した樹脂組成物Ａを得ることが可能となる。このように、この調製方法によれば、セルロース繊維の分散性が向上するため、重合反応前に添加したセルロース繊維の平均繊維径よりも、重合反応終了後に混合物中に含有されているセルロース繊維のほうが、平均繊維径や繊維長が小さいものとなることもある。 In such a preparation method, cellulose fibers having an average fiber diameter of 10 μm or less are used, and the cellulose fibers are subjected to a polymerization reaction in an aqueous dispersion, thereby being subjected to a polymerization reaction with good dispersibility. Become. Furthermore, the cellulose fibers subjected to the polymerization reaction are improved in dispersibility by agitation with the monomer and water during the polymerization reaction and by stirring at the above temperature conditions, and the fibers aggregate. It is possible to obtain a resin composition A in which cellulose fibers having a small average fiber diameter are well dispersed. Thus, according to this preparation method, since the dispersibility of the cellulose fibers is improved, the cellulose fibers contained in the mixture after the completion of the polymerization reaction are more than the average fiber diameter of the cellulose fibers added before the polymerization reaction. However, the average fiber diameter and fiber length may be smaller.
　また、この調製方法では、セルロース繊維を乾燥させる工程が不要となり、微細なセルロース繊維の飛散が生じる工程を経ずに製造が可能であるため、操業性よく樹脂組成物Ａを得ることが可能となる。またモノマーとセルロースを均一に分散させる目的として水を有機溶媒に置換する必要がないため、ハンドリングに優れるとともに製造工程中において化学物質の排出を抑制することが可能となる。 In addition, in this preparation method, the step of drying the cellulose fibers is not necessary, and the production can be performed without the step of causing the scattering of fine cellulose fibers, so that the resin composition A can be obtained with good operability. Become. Moreover, since it is not necessary to replace water with an organic solvent for the purpose of uniformly dispersing the monomer and cellulose, the handling is excellent and the discharge of chemical substances can be suppressed during the production process.
　ここで、本発明における樹脂組成物Ａとは、上記したように、水を含んだ状態のセルロース繊維の存在下に、ポリアミド樹脂を構成するモノマーの重合反応を行うことにより得られたものである。ただし、この重合反応時に、後述する樹脂組成物中に添加することができる添加剤を添加した場合は、樹脂組成物Ａとは、該添加剤も含むものをいう。 Here, as described above, the resin composition A in the present invention is obtained by performing a polymerization reaction of monomers constituting the polyamide resin in the presence of cellulose fibers containing water. . However, when an additive that can be added to the resin composition described later is added at the time of this polymerization reaction, the resin composition A means one that also contains the additive.
　なお、上記方法で調製した樹脂組成物Ａの相対粘度は、特に制限はないが、１．５～５．０であることが好ましく、１．７～４．０であることがより好ましい。相対粘度が１．５未満では、均一な発泡セルが生成しにくく、発泡成形性が低下し、また、機械的特性も低下する。一方、相対粘度が５．０を超えると、樹脂組成物Ａの流動性が低下するため、発泡成形性が低下する。なお、相対粘度の測定方法は後述するが、溶媒として９６％硫酸を用い、温度２５℃、濃度１ｇ／１００ｍｌの条件において行った。 The relative viscosity of the resin composition A prepared by the above method is not particularly limited, but is preferably 1.5 to 5.0, and more preferably 1.7 to 4.0. When the relative viscosity is less than 1.5, it is difficult to form uniform foam cells, foam moldability is lowered, and mechanical properties are also lowered. On the other hand, when the relative viscosity exceeds 5.0, the fluidity of the resin composition A is lowered, and the foam moldability is lowered. In addition, although the measuring method of relative viscosity is mentioned later, 96% sulfuric acid was used as a solvent, and the temperature was 25 ° C. and the concentration was 1 g / 100 ml.
　また、樹脂組成物Ａの伸長粘度は、８．００×１０３～６．００×１０５Ｐａ・ｓであることが好ましく、中でも１．００×１０４～９．５０×１０４Ｐａ・ｓであることが好ましい。伸長粘度が上記範囲内であると、発泡に適した粘性を有するものとなり、発泡セルの大きさが均一であり、かつ適度な大きさの発泡セルが多数形成されるため、表面外観、耐衝撃性に優れたものとなる。
　中でも好ましい範囲である、１．００×１０４～９．５０×１０４Ｐａ・ｓの伸長粘度を有する樹脂組成物Ａは、樹脂組成物中のセルロース繊維の平均繊維径を、上記した最も好ましい範囲である４０～１００ｎｍとなるようにし、かつセルロース繊維の含有量を、上記した最も好ましい範囲である０．５～５質量部とすることで調製することができる。
　なお、樹脂組成物Ａ中のセルロース繊維の平均繊維径が、最も好ましい範囲である４０～１００ｎｍの範囲を超えても、樹脂組成物Ａの伸長粘度が１．００×１０４～９．５０×１０４Ｐａ・ｓの範囲となる場合もあるが、セルロース繊維の平均繊維径が１００ｎｍを超えると、得られる発泡成形体はセル径の大きい発泡セルが生じ、均一性にやや劣るものとなりやすい。
　したがって、本発明においては、樹脂組成物Ａは、セルロース繊維の平均繊維径が４０～１００ｎｍであり、かつ伸長粘度が１．００×１０４～９．５０×１０４Ｐａ・ｓであることが最も好ましい。 The elongation viscosity of the resin composition A is preferably 8.00 × 10 3 to 6.00 × 10 5 Pa · s, and more preferably 1.00 × 10 4 to 9.50 × 10 4 Pa · s. It is preferable that When the extensional viscosity is within the above range, it has a viscosity suitable for foaming, the foam cell size is uniform, and a large number of foam cells of appropriate size are formed. Excellent in properties.
Among these, the resin composition A having an elongation viscosity of 1.00 × 10 4 to 9.50 × 10 4 Pa · s, which is a preferable range, has the average fiber diameter of the cellulose fibers in the resin composition as described above. The content can be adjusted to 40 to 100 nm, and the cellulose fiber content can be adjusted to 0.5 to 5 parts by mass, which is the most preferable range described above.
Even if the average fiber diameter of the cellulose fibers in the resin composition A exceeds the most preferable range of 40 to 100 nm, the elongation viscosity of the resin composition A is 1.00 × 10 4 to 9.50 ×. Although it may be in the range of 10 4 Pa · s, when the average fiber diameter of the cellulose fibers exceeds 100 nm, the resulting foamed molded product has foam cells having a large cell diameter and tends to be somewhat inferior in uniformity.
Therefore, in the present invention, the resin composition A has an average fiber diameter of 40 to 100 nm and an elongational viscosity of 1.00 × 10 4 to 9.50 × 10 4 Pa · s. Most preferred.
＜発泡核剤＞
　本発明における樹脂組成物は、上記したポリアミド樹脂とセルロース繊維（樹脂組成物Ａ）に加えて、発泡核剤を含有するものである。本発明で用いられる発泡核剤としては、酸化チタン、タルク、カオリン、クレイ、珪酸カルシウム、シリカ、クエン酸ソーダ、炭酸カルシウム、珪藻土、焼成パーライト、ゼオライト、ベントナイト、ガラス、石灰石、硫酸カルシウム、酸化アルミニウム、酸化チタン、炭酸マグネシウム、炭酸ナトリウム、炭酸第二鉄、ポリテトラフルオロエチレン粉末などが挙げられる。 <Foaming nucleating agent>
The resin composition in the present invention contains a foam nucleating agent in addition to the above-described polyamide resin and cellulose fiber (resin composition A). Examples of the foam nucleating agent used in the present invention include titanium oxide, talc, kaolin, clay, calcium silicate, silica, sodium citrate, calcium carbonate, diatomaceous earth, calcined perlite, zeolite, bentonite, glass, limestone, calcium sulfate, aluminum oxide. , Titanium oxide, magnesium carbonate, sodium carbonate, ferric carbonate, polytetrafluoroethylene powder, and the like.
　樹脂組成物中の発泡核剤の含有量は、ポリアミド樹脂１００質量部に対して、０．０１～１５質量部であることが必要であり、中でも０．１～１２質量部であることが好ましく、さらには０．２～８質量部であることが好ましく、より好ましくは０．２～５質量部である。発泡核剤の含有量が、０．０１質量部未満である場合は、得られる発泡成形体は、発泡核剤を添加した効果が現れずに、気泡が粗大となり、発泡が不十分となりやすく、見掛け全体密度が大きいものとなり、また表面外観に劣るものとなる。一方、発泡核剤の含有量が、１５質量部を超える場合は、気泡数が過剰となり、破泡が生じやすくなり、発泡成形体は、表面外観に劣るものとなる。 The content of the foam nucleating agent in the resin composition is required to be 0.01 to 15 parts by mass with respect to 100 parts by mass of the polyamide resin, and preferably 0.1 to 12 parts by mass. Further, it is preferably 0.2 to 8 parts by mass, and more preferably 0.2 to 5 parts by mass. When the content of the foam nucleating agent is less than 0.01 parts by mass, the resulting foamed molded product does not have the effect of adding the foam nucleating agent, and the bubbles are coarse and foaming tends to be insufficient. The apparent overall density is large, and the surface appearance is inferior. On the other hand, when the content of the foam nucleating agent exceeds 15 parts by mass, the number of bubbles becomes excessive and bubble breakage is likely to occur, and the foamed molded article is inferior in surface appearance.
＜樹脂組成物＞
　本発明における樹脂組成物は、上記調製方法によって得られたポリアミド樹脂とセルロース繊維とからなる樹脂組成物Ａに、発泡核剤を混合することによって、製造することができる。混合方法としては、溶融混練時の混合や重合時添加による混合などが挙げられる。 <Resin composition>
The resin composition in this invention can be manufactured by mixing a foaming nucleating agent with the resin composition A which consists of the polyamide resin and cellulose fiber obtained by the said preparation method. Examples of the mixing method include mixing during melt kneading and mixing by addition during polymerization.
　本発明における樹脂組成物には、その特性を大きく損なわない限りにおいて、他の重合体が含有されていてもよい。このような重合体としては、ポリブタジエン、ブタジエン－スチレン共重合体、アクリルゴム、エチレン－プロピレン共重合体、エチレン－プロピレン－ジエン共重合体、天然ゴム、塩素化ブチルゴム、塩素化ポリエチレンなどのエラストマー、およびこれらの無水マレイン酸などによる酸変性物、スチレン－無水マレイン酸共重合体、スチレン－フェニルマレイミド共重合体、ポリ塩化ビニル、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリアセタール、ポリフッ化ビニリデン、ポリスルホン、ポリフェニレンサルファイド、ポリエーテルスルホン、フェノキシ樹脂、ポリフェニレンエーテル、ポリメチルメタクリレート、ポリエーテルケトン、ポリアリレート、ポリカーボネート、ポリテトラフルオロエチレンなどが挙げられる。 The resin composition in the present invention may contain other polymers as long as the characteristics are not significantly impaired. Such polymers include polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, natural rubber, chlorinated butyl rubber, elastomers such as chlorinated polyethylene, And acid-modified products thereof such as maleic anhydride, styrene-maleic anhydride copolymer, styrene-phenylmaleimide copolymer, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyvinylidene fluoride, polysulfone, polyphenylene sulfide , Polyethersulfone, phenoxy resin, polyphenylene ether, polymethyl methacrylate, polyether ketone, polyarylate, polycarbonate, polytetrafluoroethylene, etc. It is below.
　さらに、本発明における樹脂組成物には、その特性を大きく損なわない限りにおいて、膨潤性雲母、非膨潤性雲母、合成スメクタイトなどの層状珪酸塩、ガラス繊維、炭素繊維、タルク、クレイ、マイカ、ワラストナイト、炭酸カルシウム、硫酸バリウムなどの強化材、熱安定剤、酸化防止剤、顔料、着色防止剤、耐候剤、難燃剤、可塑剤、結晶核剤、離型安定剤等が含有されていてもよい。顔料としては、ニグロシン、カーボンブラック、二酸化チタン、亜鉛華、硫化亜鉛、リトポン、鉛白、アンチモン白、炭酸カルシウム、アルミナホワイト、金属粉顔料等が挙げられる。 Furthermore, the resin composition in the present invention has layered silicates such as swellable mica, non-swellable mica, and synthetic smectite, glass fiber, carbon fiber, talc, clay, mica, wax, and the like, as long as the characteristics are not significantly impaired. Contains reinforcements such as lastite, calcium carbonate, barium sulfate, heat stabilizers, antioxidants, pigments, anti-coloring agents, weathering agents, flame retardants, plasticizers, crystal nucleating agents, mold release stabilizers, etc. Also good. Examples of the pigment include nigrosine, carbon black, titanium dioxide, zinc white, zinc sulfide, lithopone, lead white, antimony white, calcium carbonate, alumina white, and metal powder pigment.
＜発泡成形体＞
　本発明の発泡成形体は、上記樹脂組成物から構成され、発泡セルを有するものである。
　上記のように、樹脂組成物は、平均繊維径が小さいセルロース繊維と発泡核剤を特定量含有するため、この樹脂組成物を発泡させることにより、大きさが均一でかつ細かい発泡セルを多量に含む発泡成形体が得られる。このような発泡成形体の形成は、ポリアミド樹脂中に微細なセルロース繊維が適量含有することによって、ポリアミド樹脂が架橋されたような構造となり、セルロースを含有するポリアミド樹脂組成物の伸長粘度が高くなること、さらにこのようなポリアミド樹脂中に発泡核剤を適量含有することによるものとみられる。 <Foamed molded product>
The foamed molded product of the present invention is composed of the above resin composition and has foamed cells.
As described above, since the resin composition contains a specific amount of cellulose fibers having a small average fiber diameter and a foam nucleating agent, by foaming this resin composition, a large amount of foam cells that are uniform in size and fine are produced. A foamed molded product containing is obtained. Formation of such a foam-molded product has a structure in which the polyamide resin is cross-linked by containing an appropriate amount of fine cellulose fibers in the polyamide resin, and the elongation viscosity of the polyamide resin composition containing cellulose is increased. Furthermore, it is considered that this is due to containing an appropriate amount of a foam nucleating agent in such a polyamide resin.
　本発明の発泡成形体は、発泡セルを有するものであるが、中でもコア層とスキン層とから構成され、コア層が発泡セルを有することが好ましい。中でもコアバック射出成形法により成形した、コア層とスキン層を有する発泡成形体であることが好ましい。
　上記コアバック射出成形法は、スキン層の形成の際に、樹脂組成物の結晶化をある程度促進させた後、コア部を後退させる成形方法である。結晶化速度の速い樹脂組成物をこの方法で成形すると、スキン層を結晶化させると同時にコア層部分の樹脂組成物も結晶化してしまい、コア部を後退させても発泡せず、発泡成形体を得ることができない。
　しかし、本発明の発泡成形体を構成する樹脂組成物は、含有するセルロース繊維の平均繊維径が小さく、ポリアミド樹脂の結晶化速度が高められておらず、適度な結晶性を有するものであるため、コアバック射出成形することにより、コア層とスキン層を有する発泡成形体を得ることができる。
　このようなコア層とスキン層を有する本発明の発泡成形体は、スキン層に、スワールマークやシルバーストリークスやヒケ等が生じることのない、表面外観及び表面平滑性に優れるものとなる。そして、スキン層を有することで、耐衝撃性にも優れた発泡成形体とすることができる。
　本発明の発泡成形体におけるコア層とスキン層の厚みの比（コア層／スキン層）は、１／５～５／１であることが好ましい。この範囲よりスキン層の厚みが大きい場合は、発泡セルの数が少なくなり、見掛け全体密度が大きくなり、１．１ｇ／ｃｍ３を超えるものとなりやすい。一方、この範囲よりスキン層の厚みが小さくなる場合は、上記したような優れた表面外観や表面平滑性を得ることが困難となりやすく、また、耐衝撃性が劣るものとなりやすい。 Although the foaming molding of this invention has a foam cell, it is comprised especially from a core layer and a skin layer, and it is preferable that a core layer has a foam cell. Among them, a foamed molded article having a core layer and a skin layer, which is molded by a core back injection molding method, is preferable.
The core back injection molding method is a molding method in which the crystallization of the resin composition is promoted to some extent during the formation of the skin layer, and then the core portion is retracted. When a resin composition having a high crystallization speed is molded by this method, the skin layer is crystallized and at the same time, the resin composition of the core layer portion is crystallized. Can't get.
However, since the resin composition constituting the foamed molded article of the present invention has a small average fiber diameter of cellulose fibers contained therein, the crystallization speed of the polyamide resin is not increased, and it has moderate crystallinity. By performing core back injection molding, a foamed molded article having a core layer and a skin layer can be obtained.
The foamed molded product of the present invention having such a core layer and skin layer is excellent in surface appearance and surface smoothness without causing swirl marks, silver streaks, sink marks and the like in the skin layer. And it can be set as the foaming molding excellent also in impact resistance by having a skin layer.
The thickness ratio (core layer / skin layer) of the core layer and the skin layer in the foamed molded article of the present invention is preferably 1/5 to 5/1. When the thickness of the skin layer is larger than this range, the number of foamed cells is reduced, the apparent overall density is increased, and tends to exceed 1.1 g / cm 3 . On the other hand, when the thickness of the skin layer is smaller than this range, it is difficult to obtain the excellent surface appearance and surface smoothness as described above, and the impact resistance tends to be inferior.
　本発明の発泡成形体が有する発泡セルは、大きさを細かいものとすることができる。発泡セルの最大セル径は２ｍｍ以下であることが好ましく、１．５ｍｍ以下であることがより好ましく、中でも０．９ｍｍ以下であることが最も好ましい。最大セル径が２ｍｍを超えると、発泡成形体は、表面外観に劣り、耐衝撃性を有しておらず、機械的物性でバラつきが生じやすいものとなる。 The foamed cell of the foamed molded product of the present invention can have a fine size. The maximum cell diameter of the foam cell is preferably 2 mm or less, more preferably 1.5 mm or less, and most preferably 0.9 mm or less. When the maximum cell diameter exceeds 2 mm, the foamed molded article is inferior in surface appearance, does not have impact resistance, and tends to vary due to mechanical properties.
　また、本発明の発泡成形体が有する発泡セルは、大きさを均一なものとすることができる。本発明においては、均一性を、発泡セルの最大セル径と平均セル径の差（最大セル径－平均セル径）で評価した。つまり、この差が小さければ発泡セルが均一であるとした。最大セル径と平均セル径の差は１．３ｍｍ以下であることが好ましく、１．１ｍｍ以下であることがより好ましく、０．６ｍｍ以下であることが最も好ましい。この差が、１．３ｍｍを超えると、発泡セルは均一性に乏しいものであり、発泡成形体は、圧力がかかった際に、発泡セルを起点として破壊が生じやすくなり、耐衝撃性などの機械的物性が低くなることがあり、また機械的物性にバラつきが生じやすくなる。 Further, the foamed cells of the foamed molded product of the present invention can be made uniform in size. In the present invention, the uniformity was evaluated by the difference between the maximum cell diameter and the average cell diameter of the foamed cells (maximum cell diameter−average cell diameter). That is, if this difference is small, the foamed cells are assumed to be uniform. The difference between the maximum cell diameter and the average cell diameter is preferably 1.3 mm or less, more preferably 1.1 mm or less, and most preferably 0.6 mm or less. If this difference exceeds 1.3 mm, the foamed cells have poor uniformity, and the foamed molded product is likely to break starting from the foamed cells when pressure is applied, such as impact resistance. The mechanical properties may be lowered, and the mechanical properties are likely to vary.
　本発明の発泡成形体は、ＪＩＳ　Ｋ　７２２２に準じて測定し、算出した見掛け全体密度が１．１ｇ／ｃｍ３以下であることが好ましく、中でも０．９ｇ／ｃｍ３以下であることが好ましく、０．７ｇ／ｃｍ３以下であることが最も好ましい。発泡成形体は、見掛け全体密度が、１．１ｇ／ｃｍ３を超えると、軽量化効果が不十分となる。なお、見掛け全体密度が０．２ｇ／ｃｍ３未満であると、発泡セルの量が多くなりすぎ、耐衝撃性が低いものとなりやすい。 The foamed molded article of the present invention is measured according to JIS K 7222, and the calculated apparent total density is preferably 1.1 g / cm 3 or less, more preferably 0.9 g / cm 3 or less. Most preferably, it is 0.7 g / cm 3 or less. If the foamed molded body has an apparent total density exceeding 1.1 g / cm 3 , the effect of reducing the weight becomes insufficient. In addition, when the apparent overall density is less than 0.2 g / cm 3 , the amount of the foamed cell is excessively increased, and the impact resistance tends to be low.
　また、本発明の発泡成形体は、例えば研磨材により金型表面を研磨して鏡面加工仕上げをした金型を用いて、コアバック射出成形法でコア層とスキン層を形成することにより、表面を鏡面加工したものとすることができる。このような鏡面加工した発泡成形体は、黒色に着色されていることが好ましく、中でも黒色色素を含有する樹脂組成物を用いて成形されることが好ましい。
　本発明でいう黒色色素としては、黒色顔料や黒色染料などが挙げられ、具体的には、カーボンブラックやニグロシン、チタンと鉄の複合酸化物、アニリンブラックなどが挙げられる。黒色色素は、２種類以上のものを混合して用いてもよい。
　本発明の発泡成形体における黒色色素の含有量は、ポリアミド樹脂１００質量部に対して、０．１～５．０質量部であることが好ましく、０．１～３質量部であることがより好ましい。
　なお、黒色色素は、ポリアミド樹脂とセルロース繊維を含む樹脂組成物Ａに混合することが好ましく、混合方法としては、溶融混練時の混合や重合時添加による混合などが挙げられる。
　また、本発明の発泡成形体は、シボ加工仕上げをした金型を用いて、コアバック射出成形法でコア層とスキン層を形成することにより、表面をシボ加工したものとすることができる。 In addition, the foam molded body of the present invention can be obtained by forming a core layer and a skin layer by a core back injection molding method using, for example, a mold having a mirror finish by polishing the mold surface with an abrasive. Can be mirror-finished. Such a mirror-finished foam molded article is preferably colored black, and is preferably molded using a resin composition containing a black pigment.
Examples of the black pigment in the present invention include black pigments and black dyes. Specific examples include carbon black, nigrosine, titanium-iron composite oxide, and aniline black. Two or more types of black pigments may be mixed and used.
The black pigment content in the foamed molded product of the present invention is preferably 0.1 to 5.0 parts by mass, more preferably 0.1 to 3 parts by mass, with respect to 100 parts by mass of the polyamide resin. preferable.
In addition, it is preferable to mix a black pigment | dye into the resin composition A containing a polyamide resin and a cellulose fiber, and the mixing method includes the mixing at the time of melt-kneading and the addition by the polymerization.
Further, the foamed molded article of the present invention can be obtained by applying a textured surface by forming a core layer and a skin layer by a core back injection molding method using a textured finish mold.
　本発明の発泡成形体は、上記したように耐衝撃性に優れるものである。耐衝撃性の評価は、発泡成形体を切削加工した試験片を用いて、ＪＩＳ　Ｋ　７１１１－１に準じたノッチなしシャルピー衝撃強さで行った。発泡成形体で行われたシャルピー衝撃強度は、２８ｋＪ／ｍ２以上であることが好ましく、３０ｋＪ／ｍ２以上であることがより好ましい。発泡成形体は、シャルピー衝撃強度が２８ｋＪ／ｍ２未満であると、耐衝撃性がなく、実用的なものでなくなる。 The foamed molded product of the present invention is excellent in impact resistance as described above. The impact resistance was evaluated by using notch-free Charpy impact strength according to JIS K 7111-1, using a test piece obtained by cutting a foamed molded product. Charpy impact strength was performed in expanded molded article is preferably at 28kJ / m 2 or more, more preferably 30 kJ / m 2 or more. If the foamed molded article has a Charpy impact strength of less than 28 kJ / m 2 , it has no impact resistance and is not practical.
＜発泡成形体の製造法＞
　次に、本発明の発泡成形体の製造法について説明する。
　本発明の発泡成形体は、上記した樹脂組成物を発泡成形したものであり、発泡成形に用いることができる発泡剤としては、熱分解型発泡剤として、アゾ、Ｎ－ニトロソ、複素環式窒素含有及びスルホニルヒドラジド基のような分解しうる基を含有する有機化合物、炭酸アンモニウムや炭酸水素ナトリウムなどの無機化合物を挙げることができる。その具体例としては、アゾジカルボンアミド、アゾビスイソブチロニトリル、アゾシクロヘキシルニトリル、ジアゾアミノベンゼン、ジニトロソペンタメチレンテトラミン、Ｎ，Ｎ′－ジメチル－Ｎ，Ｎ′－ジニトロソテレフタルアミド、ベンゼンスルホニルヒドラジド、４，４′－オキシ－ビス（ベンゼンスルホニル）ヒドラジド、ジフェニルスルホン－３，３′－ジスルホニルヒドラジド、４－トルエンスルホニルヒドラジド、４，４′－オキシ－ビス（ベンゼンスルホニル）セミカルバジド、４－トルエンスルホニルセミカルバジド、バリウムアゾジカルボキシレート、５－フェニルテトラゾール、トリヒドラジノトリアジン、４－トルエンスルフォニルアザイド、４，４′－ジフェニルジスルフォニルアザイドなどが挙げられる。
　また、発泡剤として、液状フルオロカーボン、ペンタンなどの常温で液体のものや、ガス状フルオロカーボン、窒素、二酸化炭素、空気、ヘリウム、アルゴンなど常温で気体のものや液化したものも使用することができる。 <Method for producing foamed molded article>
Next, the manufacturing method of the foaming molding of this invention is demonstrated.
The foamed molded article of the present invention is obtained by foam-molding the above resin composition. Examples of foaming agents that can be used for foam molding include pyrolytic foaming agents such as azo, N-nitroso, and heterocyclic nitrogen. Examples thereof include organic compounds containing and decomposable groups such as sulfonyl hydrazide groups, and inorganic compounds such as ammonium carbonate and sodium hydrogen carbonate. Specific examples thereof include azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, diazoaminobenzene, dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosotephthalamide, benzenesulfonyl Hydrazide, 4,4'-oxy-bis (benzenesulfonyl) hydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4-toluenesulfonyl hydrazide, 4,4'-oxy-bis (benzenesulfonyl) semicarbazide, 4- Examples include toluenesulfonyl semicarbazide, barium azodicarboxylate, 5-phenyltetrazole, trihydrazinotriazine, 4-toluenesulfonyl azide, 4,4′-diphenyldisulfonyl azide, and the like.
In addition, as the foaming agent, liquids such as liquid fluorocarbons and pentanes that are liquid at room temperature, and gaseous fluorocarbons, nitrogen, carbon dioxide, air, helium, argon, and the like that are gaseous or liquefied can be used.
　樹脂組成物中の発泡剤の配合量は、ポリアミド樹脂１００質量部に対して、０．０５～２質量部であることが好ましく、０．１～１質量部であることがより好ましい。発泡剤の配合量が０．０５質量部未満では、発泡するガスの量が少なく、発泡倍率が上がらず、得られる発泡成形体の見掛け全体密度が大きいものとなり、質量減少効果が得られない場合がある。一方、配合量が２質量部を超えると、得られる発泡成形体の機械的強度が低下する場合や、シルバーストリークスやスワールマークの発生等の表面外観を損ねる場合がある。 The blending amount of the foaming agent in the resin composition is preferably 0.05 to 2 parts by mass and more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the polyamide resin. When the blending amount of the foaming agent is less than 0.05 parts by mass, the amount of gas to be foamed is small, the expansion ratio is not increased, the apparent overall density of the resulting foamed molded article is large, and the mass reduction effect cannot be obtained. There is. On the other hand, if the blending amount exceeds 2 parts by mass, the mechanical strength of the obtained foamed molded product may be lowered, or the surface appearance such as generation of silver streak or swirl mark may be impaired.
　本発明の発泡成形体は、上記した樹脂組成物と発泡剤とを使用して、常法により発泡成形される。例えば、発泡剤が固体であるときには、得られた樹脂組成物を、ペレット状もしくは粉末状にした後、発泡剤と混合し、次いでこの混合物を成形機中に供給、溶融し、射出成形して発泡成形体を得ることができる。発泡剤は直接添加してもよいが、予め熱可塑性樹脂と発泡剤を溶融混練したマスターバッチペレットを用いて添加してもよい。また、ディスクペレッターなどを用いて発泡核剤とバインダーなどを発泡剤と押し固めたマスターバッチペレットを用いてもよい。発泡剤が気体や液体であるときには、ミューセル発泡で代表されるように、溶融樹脂組成物中に発泡剤を直接加えて均一に分散させ、成形時に発泡させ、発泡成形体とすることができる。 The foam molded article of the present invention is foam-molded by a conventional method using the resin composition and the foaming agent described above. For example, when the foaming agent is solid, the obtained resin composition is pelletized or powdered, mixed with the foaming agent, and then the mixture is fed into a molding machine, melted, and injection molded. A foamed molded product can be obtained. The foaming agent may be added directly, or may be added using a master batch pellet obtained by melt-kneading a thermoplastic resin and a foaming agent in advance. Moreover, you may use the masterbatch pellet which pressed the foaming nucleating agent, the binder, etc. with the foaming agent using the disk pelleter. When the foaming agent is a gas or liquid, as represented by mucell foaming, the foaming agent is directly added to the molten resin composition and uniformly dispersed, and foamed at the time of molding to obtain a foamed molded article.
　発泡成形体の表面外観や機械的強度を向上させるためには、発泡セルが存在するコア層を、発泡セルが存在しないスキン層で包括した構成とすることが好ましい。
　このような発泡成形体は、例えば、射出成形機において、溶融した発泡性の樹脂組成物を金型キャビティに射出し、溶融樹脂が流動末端付近に到達した時点で０．２～１．０秒間、２０～１００ＭＰaの保圧をかけ、次いで金型キャビティに隣接した金型コア部を１０～１００ｍｍ／秒の速度で、中型キャビティの厚みが拡張する方向へ後退させる射出コアバック式の射出成形方法で得ることができる。 In order to improve the surface appearance and mechanical strength of the foamed molded article, it is preferable that the core layer in which the foamed cells exist is covered with a skin layer in which the foamed cells do not exist.
Such a foamed molded article is produced, for example, by injecting a molten foamable resin composition into a mold cavity in an injection molding machine, and when the molten resin reaches the vicinity of the flow end for 0.2 to 1.0 seconds. An injection core back type injection molding method in which a holding pressure of 20 to 100 MPa is applied, and then the mold core portion adjacent to the mold cavity is retracted at a speed of 10 to 100 mm / sec in a direction in which the thickness of the middle mold cavity is expanded. Can be obtained at
　コアバック式の射出成形方法において、設定発泡倍率（Ｘ）は、ダイプレートの後退距離と金型キャビティの初期深さより次式を用いて求められる。
　　設定発泡倍率（Ｘ）＝（初期深さ＋ダイプレートの後退距離）／（初期深さ）
　また、このときの発泡の実倍率（Ｙ）は、未発泡体の密度（ρ０）と発泡成形体の密度（ρ１）の比（ρ０／ρ１）として算出することができる。
　発泡の実倍率は１．１５～３．００であることが好ましく、１．２５～２．６０であることがより好ましい。発泡の実倍率が１．１５未満であると、発泡成形体の軽量化効果が不十分であり、３．００を超えると、発泡成形体中でコア層の発泡セルが粗大化する場合や、スキン層が薄くなる場合があり、発泡成形体の機械的強度が低下する。
　設定発泡倍率（Ｘ）、発泡の実倍率（Ｙ）より算出される発泡効率（Ｙ／Ｘ）は、表面平滑性の指標となるものであり、８５％以上であることが好ましく、９０％以上であることがより好ましい。発泡効率（Ｙ／Ｘ）が８５％以上であることにより、金型内で発泡する発泡成形体が、金型との密着性を増し、発泡成形体の表面平滑性が向上する。 In the core back type injection molding method, the set foaming ratio (X) is obtained by the following formula from the retreat distance of the die plate and the initial depth of the mold cavity.
Set foaming ratio (X) = (initial depth + retract distance of die plate) / (initial depth)
Further, the actual expansion ratio (Y) of foaming at this time can be calculated as a ratio (ρ 0 / ρ 1 ) between the density of the unfoamed body (ρ 0 ) and the density of the foamed molded body (ρ 1 ).
The actual expansion ratio is preferably 1.15 to 3.00, more preferably 1.25 to 2.60. When the actual magnification ratio of foaming is less than 1.15, the effect of reducing the weight of the foam molded article is insufficient, and when it exceeds 3.00, the foam cell of the core layer becomes coarse in the foam molded article, A skin layer may become thin and the mechanical strength of a foaming molding will fall.
The foaming efficiency (Y / X) calculated from the set foaming ratio (X) and the actual foaming ratio (Y) is an index of surface smoothness, preferably 85% or more, and preferably 90% or more. It is more preferable that When the foaming efficiency (Y / X) is 85% or more, the foamed molded body that foams in the mold increases the adhesion to the mold, and the surface smoothness of the foamed molded body is improved.
　本発明の発泡成形体は、表面外観が良好で、耐衝撃性に優れているので、電気・電子機器分野や、自動車分野、あるいは機械分野などの用途に好適に使用することができる。 Since the foamed molded article of the present invention has a good surface appearance and excellent impact resistance, it can be suitably used in applications such as the electric / electronic equipment field, the automobile field, and the machine field.
　以下、本発明を実施例によりさらに具体的に説明するが、本発明はこれらの実施例により限定されるものではない。
　本発明の実施例中の各種の特性の測定法や評価法は以下のとおりである。
（１）セルロース繊維の平均繊維径
（１．１）重合反応前のセルロース繊維の平均繊維径
　必要に応じて凍結乾燥したセルロース繊維を、電界放射型走査型電子顕微鏡（日立製作所社製Ｓ－４０００）を用いて観察した。電子顕微鏡（ＳＥＭ）画像からセルロース繊維（単繊維）の長手方向に対する垂直方向の長さを測定した。このとき、垂直方向の長さのうち最大のものを繊維径とした。同様にして１０本のセルロース繊維（単繊維）の繊維径を測定し、１０本の平均値を算出したものを平均繊維径とした。
（１．２）発泡成形体を構成する樹脂組成物中のセルロース繊維の平均繊維径
　得られた鏡面加工発泡成形体から、凍結ウルトラミクロトームを用いて厚さ１００ｎｍの切片を採取し、ＯｓＯ４（四酸化オスミウム）で切片染色を実施後、透過型電子顕微鏡（日本電子社製ＪＥＭ－１２３０）を用いて観察を行った。電子顕微鏡画像からセルロース繊維（単繊維）の長手方向に対する垂直方向の長さを測定した。このとき、垂直方向の長さのうち最大のものを繊維径とした。同様にして１０本のセルロース繊維（単繊維）の繊維径を測定し、１０本の平均値を算出したものを平均繊維径とした。
　なお、セルロース繊維の繊維径が大きいものについては、ミクロトームにて１０μｍの切片を切り出したものか、発泡成形体をそのままの状態で、実体顕微鏡（ＯＬＹＭＰＵＳ　ＳＺ－４０）を用いて観察を行い、得られた画像から上記と同様にして繊維径を測定し、平均繊維径を求めた。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
Measurement methods and evaluation methods for various characteristics in the examples of the present invention are as follows.
(1) Average fiber diameter of cellulose fibers (1.1) Average fiber diameter of cellulose fibers before polymerization reaction Cellulose fibers freeze-dried as necessary were subjected to a field emission scanning electron microscope (S-4000 manufactured by Hitachi, Ltd.). ). The length in the direction perpendicular to the longitudinal direction of the cellulose fiber (single fiber) was measured from an electron microscope (SEM) image. At this time, the maximum of the lengths in the vertical direction was taken as the fiber diameter. Similarly, the fiber diameter of 10 cellulose fibers (single fibers) was measured, and the average value of 10 fibers was calculated as the average fiber diameter.
(1.2) Average Fiber Diameter of Cellulose Fiber in Resin Composition Constructing Foam Molded Body From the obtained mirror-finished foam molded body, a 100 nm-thick slice was collected using a frozen ultramicrotome, and OsO 4 ( After performing section staining with osmium tetroxide, observation was performed using a transmission electron microscope (JEM-1230 manufactured by JEOL Ltd.). The length in the direction perpendicular to the longitudinal direction of the cellulose fiber (single fiber) was measured from the electron microscope image. At this time, the maximum of the lengths in the vertical direction was taken as the fiber diameter. Similarly, the fiber diameter of 10 cellulose fibers (single fibers) was measured, and the average value of 10 fibers was calculated as the average fiber diameter.
For cellulose fibers having a large fiber diameter, a 10 μm section was cut out with a microtome, or the foamed molded product was observed as it was using a stereomicroscope (OLYMPUS SZ-40). The fiber diameter was measured in the same manner as described above from the obtained image, and the average fiber diameter was determined.
（２）樹脂組成物中のセルロース繊維の含有量
　エスアイアイ・ナノテクノロジー社製のＴＧ／ＤＴＡ　７２００装置を用いて下記条件で測定した。
　十分に乾燥されたセルロースと樹脂をそれぞれ既知濃度となるように専用パンの中で量り取り、２９０℃から３２０℃までの重量減少を樹脂中のセルロース量として検量線を作成し、この検量線を用いて、得られた鏡面加工発泡成形体中のセルロース繊維含有量を算出した。
　このとき、鏡面加工発泡成形体は凍結粉砕して用い、試料量１０ｍｇを精密天秤で量り取り、窒素雰囲気中での昇温測定を行った。昇温条件は、３０℃から２８５℃まで５℃／ｍｉｎで昇温し、２８５℃から３２０℃まで０．６３℃／ｍｉｎで昇温し、再び３２０℃から３５０℃まで５℃／ｍｉｎ昇温し、最後に３５０℃から５５０℃まで１０℃／ｍｉｎで昇温させた。 (2) Content of cellulose fiber in resin composition Measurement was performed under the following conditions using a TG / DTA 7200 apparatus manufactured by SII Nano Technology.
Fully dried cellulose and resin are weighed in a dedicated pan so that each has a known concentration, and a calibration curve is created using the weight loss from 290 ° C to 320 ° C as the amount of cellulose in the resin. Using, the cellulose fiber content in the obtained mirror-finished foamed molded article was calculated.
At this time, the mirror-finished foamed molded product was freeze-ground and used, and a sample amount of 10 mg was weighed with a precision balance and measured for temperature rise in a nitrogen atmosphere. The temperature was raised from 30 ° C. to 285 ° C. at 5 ° C./min, from 285 ° C. to 320 ° C. at 0.63 ° C./min, and again from 320 ° C. to 350 ° C. at 5 ° C./min. Finally, the temperature was raised from 350 ° C. to 550 ° C. at 10 ° C./min.
（３）セルロース繊維を含有するポリアミド樹脂組成物（樹脂組成物Ａ）の相対粘度
　得られた樹脂組成物Ａのペレット（９５℃の熱水で処理し、精練を行い、乾燥させたもの）を用い、９６％硫酸で、温度２５℃、濃度１ｇ／１００ｍｌの条件において、相対粘度を測定した。 (3) Relative viscosity of the polyamide resin composition (resin composition A) containing cellulose fibers The obtained resin composition A pellets (treated with hot water at 95 ° C., scoured and dried) The relative viscosity was measured using 96% sulfuric acid at a temperature of 25 ° C. and a concentration of 1 g / 100 ml.
（４）セルロース繊維を含有するポリアミド樹脂組成物（樹脂組成物Ａ）の伸長粘度
　得られた樹脂組成物Ａのペレット（９５℃の熱水で処理し、精練を行い、乾燥させたもの）を、島津製作所製フローテスターＣＦ－５００装置を用い、ダイ１（ダイ径１ｍｍ、ダイ長０．２５ｍｍ）とダイ２（ダイ径１ｍｍ、ダイ長１５ｍｍ）を用いて測定した結果から伸長粘度を算出した。なお、２５０℃温度条件で行った。また、伸長粘度は、特表２０１３－５２５６２２号の段落［００２０］～［００４０］の計算式に準拠して算出した。
　ただし、比較例１においてはポリアミド樹脂のペレットを用い、比較例３においては溶融混練物のペレットを用い、比較例７においては樹脂組成物Ｂのペレットを用いて測定した。 (4) Elongation Viscosity of Polyamide Resin Composition (Resin Composition A) Containing Cellulose Fiber The obtained resin composition A pellets (treated with hot water at 95 ° C., scoured and dried) The elongation viscosity was calculated from the results of measurement using a die 1 (die diameter 1 mm, die length 0.25 mm) and die 2 (die diameter 1 mm, die length 15 mm) using a flow tester CF-500 apparatus manufactured by Shimadzu Corporation. . In addition, it carried out on 250 degreeC temperature conditions. The elongational viscosity was calculated according to the calculation formulas in paragraphs [0020] to [0040] of JP-T-2013-525622.
However, in Comparative Example 1, measurement was performed using polyamide resin pellets, in Comparative Example 3 using melt-kneaded pellets, and in Comparative Example 7 using resin composition B pellets.
（５）発泡セルの最大セル径（ａ）、平均セル径（ｂ）
　得られた鏡面加工発泡成形体が有する発泡セルのセル径を次の方法により測定し、算出した。
　鏡面加工発泡成形体のスキン層面を、その対角線に沿って、厚さ方向に切断し、切断面（以下、測定面とする）を拡大鏡もしくは顕微鏡にて観察した。そして、測定面に現れた発泡セルについて、発泡セルの外周上に存在する２点を結ぶ線分のうち、最大長さの線分を求め、その長さをＰとし、また、その線分の中点を通り、線分に垂直な方向におけるセル長さを求め、その長さをＱとし、（Ｐ＋Ｑ）／２をセル径とした。
　測定面に現れた発泡セルのうち、最大とみられる発泡セルについて、セル径を測定し、これを最大セル径とした。
　さらに、測定面を、厚さ方向に平行な５本の線分で６等分し、それぞれの線分の中点付近に存在する発泡セル１０個について、セル径を測定し、合計５０個のセル径の平均値を算出し、平均セル径（ｂ）とした。 (5) Maximum cell diameter (a) of foamed cell, average cell diameter (b)
The cell diameter of the foam cell which the obtained mirror surface processing foaming molding has was measured and calculated by the following method.
The skin layer surface of the mirror-finished foamed product was cut in the thickness direction along the diagonal line, and the cut surface (hereinafter referred to as a measurement surface) was observed with a magnifier or a microscope. And about the foam cell which appeared on the measurement surface, the line segment of the maximum length is calculated | required among the line segments which connect two points which exist on the outer periphery of a foam cell, The length is set to P, Moreover, the line segment The cell length in a direction passing through the midpoint and perpendicular to the line segment was determined, the length was defined as Q, and (P + Q) / 2 was defined as the cell diameter.
Among the foamed cells that appeared on the measurement surface, the cell diameter was measured for the foamed cell considered to be the maximum, and this was taken as the maximum cell diameter.
Further, the measurement surface was divided into 6 equal parts by 5 line segments parallel to the thickness direction, and the cell diameter was measured for 10 foam cells existing near the midpoint of each line segment, for a total of 50 cells. The average value of the cell diameter was calculated and used as the average cell diameter (b).
（６）発泡セルの均一性
　上記（５）の方法で求めた発泡セルの最大セル径（ａ）と平均セル径（ｂ）との差を求め、これを均一性の評価とした。 (6) Uniformity of foamed cell The difference between the maximum cell diameter (a) and the average cell diameter (b) of the foamed cell obtained by the method (5) was determined, and this was used as the evaluation of uniformity.
（７）見掛け全体密度
　得られた鏡面加工発泡成形体を用い、ＪＩＳ　Ｋ　７２２２に準じて測定し、算出した。 (7) Apparent whole density It measured and calculated according to JISK7222 using the obtained mirror surface processing foaming molding.
（８）発泡実倍率
　コアバックさせて得られた鏡面加工発泡成形体の密度（ρ１）と、コアバックさせずに得られた鏡面加工発泡の成形体の密度（ρ０）の比（ρ０／ρ１）として算出した。 (8) Actual foaming ratio Ratio (ρ 1 ) of the density (ρ 1 ) of the mirror-finished foamed molding obtained by core back and the density (ρ 0 ) of the mirror-finished foam obtained without core back (ρ 0 ) 0 / ρ 1 ).
（９）鏡面加工部の外観評価
　得られた鏡面加工発泡成形体の鏡面加工部表面を、下記の方法により測定して、評価した。
　鏡面加工部表面の任意の３点のＬ値を、日本電色社製の色差計ＳＥ－６０００で測定し、Ｌ値の平均値で、鏡面加工部の外観を評価した。シルバーストリークスやスワールマークがあれば、発泡成形体が白っぽくなり、Ｌ値が大きくなる。Ｌ値は１２以下であることが好ましく、１０以下であることがより好ましい。 (9) Appearance evaluation of mirror-finished portion The surface of the mirror-finished foamed product obtained was measured and evaluated by the following method.
The L values at three arbitrary points on the surface of the mirror-finished portion were measured with a color difference meter SE-6000 manufactured by Nippon Denshoku Co., Ltd., and the appearance of the mirror-finished portion was evaluated by the average value of the L values. If there is silver streak or swirl mark, the foamed molded product becomes whitish and the L value becomes large. The L value is preferably 12 or less, and more preferably 10 or less.
（１０）シボ加工部の外観評価
　得られたシボ加工発泡成形体のシボ加工部表面を観察し、成形体表面に、シルバーストリークスやスワールマーク、ヒケがないかを目視観察した。
○：表面にシルバーストリークス、スワールマーク、ヒケのいずれもない。
×：表面にシルバーストリークス、スワールマーク、ヒケのいずれかがある。 (10) Appearance evaluation of the textured portion The surface of the textured foamed molded product was observed, and the molded product surface was visually observed for silver streaks, swirl marks, and sink marks.
○: No silver streak, swirl mark, or sink mark on the surface.
X: Silver streak, swirl mark, or sink mark is present on the surface.
（１１）シャルピー衝撃試験
　得られた鏡面加工発泡成形体を切削加工した試験片を用い、ＪＩＳ　Ｋ　７１１１－１に準じノッチなしでシャルピー衝撃試験を行い、発泡成形体の耐衝撃性を評価した。なお、破壊する方の面は、切削加工で切り出していないスキン層（鏡面加工部）を有する面とした。 (11) Charpy impact test Using a test piece obtained by cutting the obtained mirror-finished foam molded article, a Charpy impact test was conducted without a notch in accordance with JIS K 7111-1, and the impact resistance of the foam molded article was evaluated. In addition, let the surface which destroys be the surface which has the skin layer (mirror surface process part) which is not cut out by cutting.
実施例１
　セルロース繊維の水分散液として、セリッシュＫＹ１００Ｇ（ダイセルファインケム社製：平均繊維径が１２５ｎｍのセルロース繊維が１０質量％含有されたもの）を使用し、これに精製水を加えてミキサーで攪拌し、セルロース繊維の含有量が３質量％の水分散液を調製した。
　このセルロース繊維の水分散液７０質量部と、ε－カプロラクタム１００質量部とを、均一な分散液となるまでさらにミキサーで攪拌、混合した。続いて、この混合分散液を攪拌しながら２４０℃に加熱し、徐々に水蒸気を放出しつつ、０ＭＰａから０．７ＭＰａの圧力まで昇圧した。そののち大気圧まで放圧し、２４０℃で１時間重合反応を行い、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）と、表１に示す量の、発泡核剤としてのタルク（日本タルク社製　ＭＩＣＲＯ　ＡＣＥ　Ｋ－１、平均粒径７．４μｍ）と、発泡剤としてのアゾジカルボンアミド（永和化成工業社製　ビニホールＡＣ♯３）と、ポリアミド樹脂１００質量部に対する量が０．３質量部であるカーボンブラックおよび０．４質量部であるニグロシンからなる黒色色素混合物とをドライブレンドして樹脂組成物を製造した。
　得られた樹脂組成物を用いてコアバック射出成形を行った。すなわち、シャットオフノズルを搭載した射出成形機（ＦＡＮＵＣ社製Ｓ－２０００ｉ）に樹脂組成物を投入し、シリンダー温度２６０℃、金型温度８０℃の条件で、鏡面加工仕上げをした金型に、射出成形した。射出成形において、０．２秒で試験片の流動末端まで充填し、次いで７５ＭＰａで０．５秒間の保圧工程を経て、その直後に６０ｍｍ／秒で射出成形機のダイプレートを設定発泡倍率２．５倍になるように後退させ、コア層とスキン層とから構成された鏡面加工発泡成形体を得た。
　またシボ加工仕上げをした金型を用いた以外は上記と同様の条件にて射出成形し、シボ加工発泡成形体を得た。 Example 1
As an aqueous dispersion of cellulose fibers, serisch KY100G (manufactured by Daicel Finechem Co., Ltd .: containing 10% by mass of cellulose fibers having an average fiber diameter of 125 nm) was added to this, and purified water was added thereto, followed by stirring with a mixer. An aqueous dispersion having a fiber content of 3% by mass was prepared.
70 parts by mass of this aqueous dispersion of cellulose fibers and 100 parts by mass of ε-caprolactam were further stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was carried out at 240 ° C. for 1 hour to obtain a resin composition A containing a polyamide resin and cellulose fibers. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
The obtained resin composition A pellets (relative viscosity ηR = 2.52) and talc (MICRO ACE K-1, manufactured by Nippon Talc Co., Ltd.) having an amount shown in Table 1 as the foam nucleating agent, an average particle size of 7.4 μm ), Azodicarbonamide as a blowing agent (Binihol AC # 3 manufactured by Eiwa Kasei Kogyo Co., Ltd.), carbon black having an amount of 0.3 parts by mass with respect to 100 parts by mass of polyamide resin, and nigrosine having 0.4 parts by mass. The resin composition was manufactured by dry blending with the black pigment mixture.
Core back injection molding was performed using the obtained resin composition. In other words, the resin composition was put into an injection molding machine (S-2000i manufactured by FANUC) equipped with a shut-off nozzle, and a mold finished with a mirror finish under conditions of a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C. Injection molded. In the injection molding, the test piece was filled in 0.2 seconds to the flow end and then subjected to a pressure holding process at 75 MPa for 0.5 seconds. Immediately thereafter, the die plate of the injection molding machine was set at 60 mm / second. It was made to recede so as to be 5 times to obtain a mirror-finished foamed molded article composed of a core layer and a skin layer.
In addition, except that a textured finish mold was used, injection molding was performed under the same conditions as above to obtain a textured foamed molded article.
製造例１：バクテリアセルロースの製造
　０．５質量％グルコース、０．５質量％ポリペプトン、０．５質量％酵母エキス、０．１質量％硫酸マグネシウム７水和物からなる組成の培地５０ｍｌを、２００ｍｌ容三角フラスコに分注し、オートクレーブで１２０℃、２０分間蒸気滅菌した。これに試験管斜面寒天培地で生育させたＧｌｕｃｏｎａｃｅｔｏｂａｃｔｅｒ　ｘｙｌｉｎｕｓ　（ＮＢＲＣ　１６６７０）を１白金耳接種し、３０℃で７日間静置培養した。７日後、培養液の上層に白色のゲル膜状のバクテリアセルロースが生成した。 Production Example 1: Production of bacterial cellulose 50 ml of a medium composed of 0.5 mass% glucose, 0.5 mass% polypeptone, 0.5 mass% yeast extract and 0.1 mass% magnesium sulfate heptahydrate was added to 200 ml. The solution was dispensed into a conical flask and steam sterilized at 120 ° C. for 20 minutes in an autoclave. One platinum ear of Gluconacetobacter xylinus (NBRC 16670) grown on a test tube slant agar medium was inoculated, and left to stand at 30 ° C. for 7 days. Seven days later, a white gel film-like bacterial cellulose was formed in the upper layer of the culture solution.
実施例２
　セルロース繊維として製造例１で得られたバクテリアセルロースを使用した。バクテリアセルロースをミキサーで破砕後、水で浸漬、洗浄を繰り返すことにより、水置換を行った。水置換後のバクテリアセルロースの水分散液（平均繊維径が６０ｎｍのバクテリアセルロースが６．５質量％含有されたもの）３５質量部と、ε－カプロラクタム１９４質量部と、アミノカプロン酸４０質量部と、精製水９０質量部とを、均一な分散液となるまでミキサーで攪拌、混合した。続いて、この混合分散液を徐々に加熱し、加熱の途中において水蒸気を排出しながら、２４０℃まで温度を上げ、２４０℃にて１時間攪拌し、重合反応を行い、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５１）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 2
The bacterial cellulose obtained in Production Example 1 was used as the cellulose fiber. Bacterial cellulose was crushed with a mixer, and then water substitution was performed by repeating immersion and washing with water. 35 parts by mass of an aqueous dispersion of bacterial cellulose after water replacement (containing 6.5% by mass of bacterial cellulose having an average fiber diameter of 60 nm), 194 parts by mass of ε-caprolactam, 40 parts by mass of aminocaproic acid, 90 parts by mass of purified water was stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C. for 1 hour to perform a polymerization reaction. The resin composition A containing this was obtained. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.51) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例３
　不織布の製造工程において屑糸として出されたセルロース繊維の集合体に、精製水を加えてミキサーで攪拌し、平均繊維径が１２０ｎｍのセルロース繊維が３質量％含有された水分散液を調製した。
　このセルロース繊維の水分散液１７０質量部と、ε－カプロラクタム２１６質量部と、アミノカプロン酸４４質量部とを、均一な分散液となるまでミキサーで攪拌、混合した。続いて、この混合分散液を徐々に加熱し、加熱の途中において水蒸気を排出しながら、２４０℃まで温度を上げ、２４０℃にて１時間攪拌し、重合反応を行い、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．３９）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 3
Purified water was added to the aggregate of cellulose fibers produced as waste yarn in the nonwoven fabric manufacturing process, and the mixture was stirred with a mixer to prepare an aqueous dispersion containing 3% by mass of cellulose fibers having an average fiber diameter of 120 nm.
170 parts by mass of this aqueous dispersion of cellulose fibers, 216 parts by mass of ε-caprolactam, and 44 parts by mass of aminocaproic acid were stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C. for 1 hour to perform a polymerization reaction. The resin composition A containing this was obtained. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the obtained pellets of resin composition A (relative viscosity ηR = 2.39) were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例４
　セルロース繊維の水分散液の量を７０質量部から１０５質量部に変更した以外は、実施例１と同様にして、重合反応を行い、樹脂組成物Ａのペレットを得て、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５０）を用い、発泡核剤と発泡剤の添加量を表１に示す量に変えた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 4
Except having changed the amount of the aqueous dispersion of cellulose fibers from 70 parts by mass to 105 parts by mass, a polymerization reaction was performed in the same manner as in Example 1 to obtain pellets of the resin composition A, and hot water at 95 ° C. , Scouring and drying.
Except that the pellets of the resin composition A obtained (relative viscosity ηR = 2.50) were used, and the addition amounts of the foam nucleating agent and the foaming agent were changed to the amounts shown in Table 1, in the same manner as in Example 1, A resin composition was produced, and then injection molded under the same conditions as in Example 1 to obtain a foam molded article.
実施例５
　セルロース繊維の水分散液として、セリッシュＫＹ１１０Ｎ（ダイセルファインケム社製：平均繊維径が１５０ｎｍのセルロース繊維が１５質量％含有されたもの）を使用した以外は実施例１と同様にセルロース繊維の含有量が３質量％になるようにセルロース水分散液を調製した。
　このセルロース繊維の水分散液７０質量部と、ε－カプロラクタム２００質量部とを、均一な分散液となるまでさらにミキサーで攪拌、混合した。続いて、この混合分散液を攪拌しながら２４０℃に加熱し、徐々に水蒸気を放出しつつ、０ＭＰａから０．７ＭＰａの圧力まで昇圧した。そののち大気圧まで放圧し、２４０℃で３時間重合反応を行い、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝３．０１）を用い、発泡核剤と発泡剤の添加量を表１に示す量に変えた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 5
The cellulose fiber content is the same as in Example 1 except that serisch KY110N (manufactured by Daicel Finechem Co., Ltd .: cellulose fiber having an average fiber diameter of 150 nm) is used as the aqueous dispersion of cellulose fibers. A cellulose aqueous dispersion was prepared so as to be 3% by mass.
70 parts by mass of this aqueous dispersion of cellulose fibers and 200 parts by mass of ε-caprolactam were further stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was carried out at 240 ° C. for 3 hours to obtain a resin composition A containing a polyamide resin and cellulose fibers. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
Except that the pellets (relative viscosity ηR = 3.01) of the obtained resin composition A were used and the addition amount of the foam nucleating agent and the foaming agent was changed to the amounts shown in Table 1, the same as in Example 1, A resin composition was produced, and then injection molded under the same conditions as in Example 1 to obtain a foam molded article.
実施例６
　２４０℃での重合反応時間を３時間から１時間に変更した以外は、実施例５と同様にして、重合反応を行い、樹脂組成物Ａのペレットを得て、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．４７）を用い、発泡核剤と発泡剤の添加量を表１に示す量に変えた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 6
Except that the polymerization reaction time at 240 ° C. was changed from 3 hours to 1 hour, the polymerization reaction was performed in the same manner as in Example 5 to obtain pellets of the resin composition A, which were treated with hot water at 95 ° C. Scouring and drying.
Except having changed the addition amount of a foam nucleating agent and a foaming agent into the quantity shown in Table 1 using the pellet (relative viscosity (eta) R = 2.47) of the obtained resin composition A, it carried out similarly to Example 1, A resin composition was produced, and then injection molded under the same conditions as in Example 1 to obtain a foam molded article.
実施例７
　ε－カプロラクタムの量を２００質量部から１００質量部に変更し、また２４０℃での重合反応時間を３時間から１時間に変更した以外は、実施例５と同様にして、重合反応を行い、樹脂組成物Ａのペレットを得て、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 7
Except that the amount of ε-caprolactam was changed from 200 parts by mass to 100 parts by mass and the polymerization reaction time at 240 ° C. was changed from 3 hours to 1 hour, the polymerization reaction was carried out in the same manner as in Example 5, A pellet of resin composition A was obtained, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.52) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例８
　セルロース繊維の水分散液として、セルロース繊維の含有量を３質量％から５質量％に変更したものを１６０質量部使用し、また２４０℃での重合反応時間を３時間から１時間に変更した以外は、実施例５と同様にして、重合反応を行い、樹脂組成物Ａを得て、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．４５）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 8
As an aqueous dispersion of cellulose fiber, 160 parts by mass of cellulose fiber content changed from 3% by mass to 5% by mass was used, and the polymerization reaction time at 240 ° C. was changed from 3 hours to 1 hour. In the same manner as in Example 5, a polymerization reaction was performed to obtain a resin composition A, which was treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.45) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例９
　セルロース繊維の水分散液として、セリッシュＫＹ１００Ｓ（ダイセルファインケム社製：平均繊維径が１８０ｎｍのセルロース繊維が２５質量％含有されたもの）を使用した以外は実施例１と同様にセルロース繊維の含有量が３質量％になるようにセルロース水分散液を調製し、実施例１と同様に重合を行って樹脂組成物Ａのペレットを得た。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．４７）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 9
The cellulose fiber content is the same as in Example 1 except that serisch KY100S (manufactured by Daicel Finechem: 25% by mass of cellulose fibers having an average fiber diameter of 180 nm) is used as the aqueous dispersion of cellulose fibers. A cellulose aqueous dispersion was prepared so as to be 3% by mass, and polymerization was performed in the same manner as in Example 1 to obtain pellets of the resin composition A.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.47) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例１０
　セルロース繊維の水分散液として、セリッシュＫＹ１００Ｓを使用した。このセルロース繊維の水分散液４９質量部と、ε－カプロラクタム２１６質量部と、アミノカプロン酸４４質量部と、精製水１５７質量部とを、均一な分散液となるまでミキサーで攪拌、混合した。続いて、この混合分散液を徐々に加熱し、加熱の途中において水蒸気を排出しながら、２４０℃まで温度を上げ、２４０℃にて１時間攪拌し、重合反応を行い、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．４３）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 10
Celish KY100S was used as an aqueous dispersion of cellulose fibers. 49 parts by mass of this cellulose fiber aqueous dispersion, 216 parts by mass of ε-caprolactam, 44 parts by mass of aminocaproic acid, and 157 parts by mass of purified water were stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed dispersion is gradually heated, and the temperature is raised to 240 ° C. while discharging steam during the heating, and the mixture is stirred at 240 ° C. for 1 hour to perform a polymerization reaction. The resin composition A containing this was obtained. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.43) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
実施例１１、１２
　実施例１で得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）を用い、発泡核剤の含有量を表１に示す量に変更した以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Examples 11 and 12
Except that the pellet of the resin composition A obtained in Example 1 (relative viscosity ηR = 2.52) was used and the content of the foam nucleating agent was changed to the amount shown in Table 1, the same procedure as in Example 1 was performed. Then, a resin composition was produced, and then injection molded under the same conditions as in Example 1 to obtain a foam molded article.
実施例１３
　セルロース繊維の水分散液として、セリッシュＫＹ１００Ｇに精製水を加えてミキサーで攪拌し、セルロース繊維の含有量を３質量％としたものを調製した。
　このセルロース繊維の水分散液１７０質量部と、ε－カプロラクタム２５４質量部と、層状珪酸塩としての膨潤性フッ素雲母（コープケミカルケミカル社製：ＭＥ-１００）２．５質量部と、亜リン酸０．２５質量部（ε－カプロラクタムに対して０．１４モル％）とを、均一な分散液となるまでミキサーで攪拌、混合した。続いて、この混合溶液を攪拌しながら２４０℃に加熱し、徐々に水蒸気を放出しつつ、０ＭＰａから０．７ＭＰａの圧力まで昇圧した。そののち大気圧まで放圧し、２４０℃で１時間重合反応を行い、ポリアミド樹脂とセルロース繊維と層状珪酸塩とを含有する樹脂組成物Ａを得た。樹脂組成物Ａを重合が終了した時点で払い出し、切断して、ペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Example 13
As an aqueous dispersion of cellulose fiber, purified water was added to SERISH KY100G and stirred with a mixer to prepare a cellulose fiber content of 3% by mass.
170 parts by mass of an aqueous dispersion of this cellulose fiber, 254 parts by mass of ε-caprolactam, 2.5 parts by mass of swellable fluorinated mica as a layered silicate (manufactured by Corp Chemical Chemical Co., Ltd .: ME-100), phosphorous acid 0.25 parts by mass (0.14 mol% based on ε-caprolactam) was stirred and mixed with a mixer until a uniform dispersion was obtained. Subsequently, the mixed solution was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was performed at 240 ° C. for 1 hour to obtain a resin composition A containing a polyamide resin, cellulose fibers, and a layered silicate. When the polymerization was completed, the resin composition A was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.52) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
比較例１
　セルロース繊維の水分散液を加えなかった以外は実施例１と同様にして、ポリアミド樹脂のペレットを得た。
　得られたペレット（相対粘度ηＲ＝２．５１）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 1
A polyamide resin pellet was obtained in the same manner as in Example 1 except that the aqueous dispersion of cellulose fiber was not added.
A resin composition was produced in the same manner as in Example 1 except that the obtained pellets (relative viscosity ηR = 2.51) were used, and then injection molded under the same conditions as in Example 1, followed by foam molding. Got the body.
比較例２
　セルロース繊維としてコットン短繊維（平均繊維径１６μｍ）を使用した以外は、実施例１と同様にして、ポリアミド樹脂とセルロース繊維とを含有する樹脂組成物Ａのペレットを得た。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５４）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 2
Except having used the cotton short fiber (average fiber diameter of 16 micrometers) as a cellulose fiber, it carried out similarly to Example 1, and obtained the pellet of the resin composition A containing a polyamide resin and a cellulose fiber.
A resin composition was produced in the same manner as in Example 1 except that the pellets of the obtained resin composition A (relative viscosity ηR = 2.54) were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
比較例３
　セルロース繊維として、セリッシュＫＹ１００Ｓを凍結乾燥後、粉砕処理を施し、粉末状としたものを調製した。
　ナイロン６（ユニチカ社製ＢＲＬ　数平均分子量１７０００）１００質量部に対して、得られた粉末状セルロース２質量部をブレンドし、スクリュー径が３０ｍｍ、平均溝深さが２．５ｍｍの二軸押出機（池貝社製ＰＣＭ－３０）に供給し、バレル温度２４０℃、スクリュー回転数１２０ｒｐｍ、滞留時間２．７分にて溶融混練した。溶融混練物を払い出し、これを切断してペレットとし、得られたペレットを乾燥させた。
　得られた溶融混練物のペレット（相対粘度ηＲ＝２．４８）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 3
As cellulose fiber, serisch KY100S was freeze-dried and then pulverized to prepare a powder.
A twin screw extruder having a screw diameter of 30 mm and an average groove depth of 2.5 mm is blended with 100 parts by mass of nylon 6 (BRL number average molecular weight 17000 manufactured by Unitika Ltd.) and 2 parts by mass of the obtained powdery cellulose. (PCM-30 manufactured by Ikegai Co., Ltd.) and melt kneaded at a barrel temperature of 240 ° C., a screw rotation speed of 120 rpm, and a residence time of 2.7 minutes. The melt-kneaded product was discharged, cut into pellets, and the resulting pellets were dried.
A resin composition was produced in the same manner as in Example 1 except that the obtained melt-kneaded pellets (relative viscosity ηR = 2.48) were used, and then injection-molded under the same conditions as in Example 1. As a result, a foamed molded product was obtained.
比較例４
　セルロース繊維の含有量が表１に示す量になるようにして重合反応をおこなった以外は、実施例１０と同様にして樹脂組成物Ａのペレットを得た。
　得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．４７）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 4
Resin composition A pellets were obtained in the same manner as in Example 10 except that the polymerization reaction was carried out so that the cellulose fiber content was as shown in Table 1.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.47) of the obtained resin composition A were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
比較例５
　実施例１で得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）に発泡核剤を加えなかった以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 5
A resin composition was produced in the same manner as in Example 1 except that no foaming nucleating agent was added to the pellets of resin composition A obtained in Example 1 (relative viscosity ηR = 2.52). Injection molding was performed under the same conditions as in Example 1 to obtain a foam molded article.
比較例６
　実施例１で得られた樹脂組成物Ａのペレット（相対粘度ηＲ＝２．５２）を用い、発泡核剤の含有量を表１に示す量に変更した以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 6
Except that the pellet of the resin composition A obtained in Example 1 (relative viscosity ηR = 2.52) was used and the content of the foam nucleating agent was changed to the amount shown in Table 1, the same procedure as in Example 1 was performed. Then, a resin composition was produced, and then injection molded under the same conditions as in Example 1 to obtain a foam molded article.
比較例７
　ε－カプロラクタム２５４質量部と、層状珪酸塩（膨潤性フッ素雲母）１０．２質量部と亜リン酸０．２５質量部（ε－カプロラクタムに対して０．１４モル％）とを、８０℃に加熱しながら均一な溶液となるまでホモジナイザーで攪拌、混合した。続いて、この混合溶液を攪拌しながら２４０℃に加熱し、徐々に水蒸気を放出しつつ、０ＭＰａから０．７ＭＰａの圧力まで昇圧した。そののち大気圧まで放圧し、２４０℃で１時間重合反応を行い、ポリアミド樹脂と層状珪酸塩とを含有する樹脂組成物Ｂを得た。樹脂組成物Ｂを重合が終了した時点で払い出し、切断してペレットとし、９５℃の熱水で処理し、精練を行い、乾燥させた。
　得られた樹脂組成物Ｂのペレット（相対粘度ηＲ＝２．５１）を用いた以外は、実施例１と同様にして、樹脂組成物を製造し、次いで実施例１と同様の条件にて射出成形し、発泡成形体を得た。 Comparative Example 7
254 parts by mass of ε-caprolactam, 10.2 parts by mass of layered silicate (swelling fluorinated mica) and 0.25 parts by mass of phosphorous acid (0.14 mol% with respect to ε-caprolactam) were heated to 80 ° C. The mixture was stirred and mixed with a homogenizer until a uniform solution was obtained while heating. Subsequently, the mixed solution was heated to 240 ° C. with stirring, and the pressure was increased from 0 MPa to 0.7 MPa while gradually releasing water vapor. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was performed at 240 ° C. for 1 hour to obtain a resin composition B containing a polyamide resin and a layered silicate. When the polymerization was completed, the resin composition B was discharged, cut into pellets, treated with hot water at 95 ° C., scoured, and dried.
A resin composition was produced in the same manner as in Example 1 except that the pellets (relative viscosity ηR = 2.51) of the obtained resin composition B were used, and then injected under the same conditions as in Example 1. Molded to obtain a foamed molded product.
　実施例１～１３、比較例１～７で得られた発泡成形体の特性値を測定した結果を表１に示す。なお、発泡体の特性値の測定に際しては、外観評価以外は鏡面加工発泡体を用いた。 Table 1 shows the measurement results of the characteristic values of the foam molded articles obtained in Examples 1 to 13 and Comparative Examples 1 to 7. In the measurement of the characteristic value of the foam, a mirror-finished foam was used except for the appearance evaluation.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～１３では、上記のように、平均繊維径が１０μｍ以下のセルロース繊維の水分散液と、ポリアミド樹脂を構成するモノマーとを混合し、モノマーの重合反応を行なうことによって、ポリアミド樹脂中に微細なセルロース繊維を凝集することなく均一に分散させ、これに発泡核剤を加えてなる樹脂組成物を、コアバック法で射出成形し、発泡成形体を得た。このため、実施例１～１３で得られた発泡成形体は、コア層とスキン層とから構成され、コア層が発泡セルを有しており、また、表１に示すように、大きさが均一でかつ細かい発泡セルを多量に有し、またシルバーストリークス、スワールマーク、ヒケ等が生じることのない表面外観が良好なものであり、耐衝撃性に優れていた。中でも実施例４～９では、樹脂組成物中のセルロース繊維の平均繊維径と含有量が最も好ましい範囲のものであったため、伸長粘度の値が最も好ましい範囲のものとなった。このため、得られた発泡成形体は、最大セル径が０．８ｍｍ以下であり、均一性が０．５ｍｍ以下であり、特に大きさが均一でかつ細かい発泡セルを多量に有し、表面外観、耐衝撃性ともに非常に優れていた。 In Examples 1 to 13, as described above, an aqueous dispersion of cellulose fibers having an average fiber diameter of 10 μm or less and a monomer constituting the polyamide resin are mixed, and the polymerization reaction of the monomer is performed, whereby the polyamide resin is mixed. A fine cellulose fiber was uniformly dispersed without agglomeration, and a resin composition obtained by adding a foam nucleating agent thereto was injection molded by the core back method to obtain a foam molded article. Therefore, the foam molded articles obtained in Examples 1 to 13 are composed of a core layer and a skin layer, and the core layer has foam cells. It had a large amount of uniform and fine foamed cells, had a good surface appearance with no silver streaks, swirl marks, sink marks, etc., and was excellent in impact resistance. In particular, in Examples 4 to 9, since the average fiber diameter and content of the cellulose fibers in the resin composition were in the most preferable range, the elongation viscosity value was in the most preferable range. For this reason, the obtained foamed molded article has a maximum cell diameter of 0.8 mm or less, a uniformity of 0.5 mm or less, a particularly large size and a large amount of fine foam cells, and a surface appearance. The impact resistance was very good.
　一方、比較例１では、樹脂組成物が、セルロース繊維を含有しないものであったため、発泡実倍率が低く発泡させにくいものであり、また得られた発泡成形体は、発泡セルが大きく不均一であった。
　比較例２では、樹脂組成物が、平均繊維径が１０μｍを超えるセルロース繊維を含有するものであったため、得られた発泡成形体は、セルロース繊維の含有量が同じである実施例１の発泡成形体と比較して、発泡セルが大きく不均一であり、またセルロースの凝集物が見られ、シルバーストリークス、スワールマーク、ヒケなどが確認され、表面外観も劣るものであり、耐衝撃性も劣っていた。
　比較例３では、ポリアミド樹脂とセルロース繊維とを溶融混練したため、セルロース繊維の分散性が低く、樹脂組成物は、セルロース繊維の凝集が目視でも確認でき、平均繊維径が大きいセルロース繊維が含有されたものであった。この樹脂組成物から得られた発泡成形体は、セルロース繊維の種類、含有量が同じである実施例９の発泡成形体と比較して、発泡セルが大きく不均一であり、表面外観が劣り、耐衝撃性にも劣るものであった。
　比較例４では、樹脂組成物が過剰にセルロース繊維を含有するものであったため、得られた発泡成形体は、発泡セルは小さいものが多く平均セル径は小さいものであったが、セル径の大きい発泡セルも生じ、均一性に劣るものであった。このため、シルバーストリークス、スワールマーク、ヒケなどが確認され、表面外観が劣り、耐衝撃性も劣るものであった。
　比較例５では、樹脂組成物が発泡核剤を含有しないものであったため、得られた発泡成形体は、セルロース繊維の含有量が同じである実施例１の発泡成形体と比較して、発泡セルが大きく不均一であり、発泡が不十分であったため見掛け全体密度が大きいものとなった。さらには、表面外観に劣り、耐衝撃性も劣るものであった。
　比較例６では、樹脂組成物が過剰に発泡核剤を含有するものであったため、得られた発泡成形体は、セルロース繊維の含有量が同じである実施例１の発泡成形体と比較すると、発泡セルは小さいものであったが、気泡数が過剰となり、破泡が生じやすくなって、セル径の大きい発泡セルも生じ、均一性に劣るものであった。このため、シルバーストリークス、スワールマーク、ヒケなどが確認され、表面外観に劣るものであった。
　比較例７では、樹脂組成物がセルロース繊維を含有せず、層状珪酸塩を含有するものであったため、得られた発泡成形体は、発泡セルは小さいものが多く平均セル径は小さいものであったが、セル径の大きい発泡セルも生じ、均一性に劣るものであった。このため、シルバーストリークス、スワールマーク、ヒケなどが確認され、表面外観が劣り、耐衝撃性も劣るものであった。
 
  On the other hand, in Comparative Example 1, since the resin composition did not contain cellulose fibers, the foaming ratio was low and it was difficult to foam, and the obtained foamed molded article had large foam cells and was not uniform. there were.
In Comparative Example 2, since the resin composition contained cellulose fibers having an average fiber diameter exceeding 10 μm, the obtained foamed molded article was foam-molded in Example 1 in which the content of cellulose fibers was the same. Compared with the body, the foam cells are large and uneven, cellulose aggregates are observed, silver streaks, swirl marks, sink marks, etc. are confirmed, the surface appearance is inferior, and the impact resistance is also inferior. It was.
In Comparative Example 3, since the polyamide resin and the cellulose fiber were melt-kneaded, the dispersibility of the cellulose fiber was low, and the resin composition was able to visually confirm the aggregation of the cellulose fiber, and contained a cellulose fiber having a large average fiber diameter. It was a thing. The foamed molded product obtained from this resin composition has a large and non-uniform foamed cell as compared with the foamed molded product of Example 9 in which the type and content of cellulose fibers are the same, and the surface appearance is inferior. It was also inferior in impact resistance.
In Comparative Example 4, since the resin composition contained excessive cellulose fibers, the obtained foamed molded article had a small number of foam cells and a small average cell diameter. Large foam cells were also formed, and the uniformity was poor. For this reason, silver streaks, swirl marks, sink marks, etc. were confirmed, the surface appearance was inferior, and the impact resistance was also inferior.
In Comparative Example 5, since the resin composition did not contain a foam nucleating agent, the obtained foamed molded product was foamed as compared with the foamed molded product of Example 1 in which the content of cellulose fibers was the same. The cells were large and uneven, and the foaming was insufficient, so that the apparent overall density was large. Furthermore, the surface appearance was inferior and the impact resistance was also inferior.
In Comparative Example 6, since the resin composition contained excessive foam nucleating agent, the obtained foamed molded product was compared with the foamed molded product of Example 1 having the same cellulose fiber content. Although the foamed cell was small, the number of bubbles became excessive and bubble breakage was likely to occur, and a foamed cell having a large cell diameter was also produced, resulting in poor uniformity. For this reason, silver streaks, swirl marks, sink marks and the like were confirmed, and the surface appearance was inferior.
In Comparative Example 7, since the resin composition did not contain cellulose fibers and contained layered silicate, the obtained foamed molded article had many small foam cells and a small average cell diameter. However, foamed cells having a large cell diameter were also produced, and the uniformity was poor. For this reason, silver streaks, swirl marks, sink marks, etc. were confirmed, the surface appearance was inferior, and the impact resistance was also inferior.

Claims (5)

  1. 　ポリアミド樹脂１００質量部に対して、平均繊維径が１０μｍ以下のセルロース繊維を０．１～１０質量部、発泡核剤を０．０１～１５質量部含有する樹脂組成物から構成され、発泡セルを有することを特徴とする発泡成形体。 A resin composition comprising 0.1 to 10 parts by weight of cellulose fibers having an average fiber diameter of 10 μm or less and 0.01 to 15 parts by weight of a foam nucleating agent with respect to 100 parts by weight of a polyamide resin. A foam-molded article comprising:
  2. 　発泡成形体がコア層とスキン層とから構成され、コア層が発泡セルを有することを特徴とする請求項１記載の発泡成形体。 The foamed molded product according to claim 1, wherein the foamed molded product comprises a core layer and a skin layer, and the core layer has foamed cells.
  3. 　発泡セルの最大セル径が２ｍｍ以下であることを特徴とする請求項１または２記載の発泡成形体。 The foamed molded article according to claim 1 or 2, wherein the maximum cell diameter of the foamed cell is 2 mm or less.
  4. 　樹脂組成物を構成するポリアミド樹脂とセルロース繊維とが、水を含んだ状態のセルロース繊維の存在下に、ポリアミド樹脂を構成するモノマーの重合反応を行うことにより得られたものであることを特徴とする請求項１～３のいずれかに記載の発泡成形体。 The polyamide resin and cellulose fiber constituting the resin composition are obtained by performing a polymerization reaction of a monomer constituting the polyamide resin in the presence of cellulose fiber containing water. The foamed molded article according to any one of claims 1 to 3.
  5. 　樹脂組成物をコアバック射出成形法により成形したものであることを特徴とする請求項１～４のいずれかに記載の発泡成形体。
     
          The foamed molded article according to any one of claims 1 to 4, wherein the resin composition is molded by a core back injection molding method.

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