WO2017110057A1 - Fiber assembly - Google Patents

Fiber assembly Download PDF

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Publication number
WO2017110057A1
WO2017110057A1 PCT/JP2016/005117 JP2016005117W WO2017110057A1 WO 2017110057 A1 WO2017110057 A1 WO 2017110057A1 JP 2016005117 W JP2016005117 W JP 2016005117W WO 2017110057 A1 WO2017110057 A1 WO 2017110057A1
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WO
WIPO (PCT)
Prior art keywords
fiber assembly
fiber
resin
mpa
temperature
Prior art date
Application number
PCT/JP2016/005117
Other languages
French (fr)
Japanese (ja)
Inventor
基 畑中
俊文 名木野
和史 宮武
航太 中平
昇 桝田
Original Assignee
パナソニックＩｐマネジメント株式会社
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
Priority claimed from JP2016187206A external-priority patent/JP6210422B2/en
Application filed by パナソニックＩｐマネジメント株式会社 filed Critical パナソニックＩｐマネジメント株式会社
Priority to US15/564,756 priority Critical patent/US20180105955A1/en
Priority to CN201680026931.6A priority patent/CN107614773A/en
Priority to EP16877962.7A priority patent/EP3396039A4/en
Publication of WO2017110057A1 publication Critical patent/WO2017110057A1/en

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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
    • D04H3/14—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic yarns or filaments produced by welding
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials

Definitions

  • the present disclosure relates to a fiber assembly.
  • a melt spinning method in which a solid thermoplastic resin is melted, and the molten thermoplastic resin (hereinafter referred to as a molten resin) is collected into fine fibers by hot air and collected to produce a fiber assembly.
  • a fiber generating device including means for discharging a molten resin and means for blowing hot air to the molten resin is used.
  • the molten resin is pulverized with hot air into fine fibers, and ultrafine fibers are produced. Then, ultrafine fibers are accumulated to produce an ultrafine fiber aggregate.
  • Patent Document 1 discloses an apparatus including a pair of slits for blowing hot air to both sides of a nozzle hole for discharging a molten resin.
  • the hot air blown out from each slit is configured to merge at the tip of the nozzle hole, thereby realizing efficient fine fiberization of the molten resin.
  • Patent Document 1 has a problem that the fiber length tends to be short because hot air is directly blown against the fibrous molten resin discharged from the nozzle holes.
  • Patent Document 2 discloses a method of obtaining long fibers by placing a molten resin in a parallel flow of hot air and stretching it.
  • Patent Document 3 discloses a method of making a molten resin into a long fiber with one parallel hot air.
  • Patent Documents 4 and 5 disclose a method of reducing the melt viscosity of a thermoplastic resin to make the molten resin fine fiber.
  • the purpose of the present disclosure is to solve the above problems and provide a fiber assembly that is extremely fine and has high strength.
  • a fiber assembly according to an aspect of the present disclosure is a fiber assembly obtained by melt spinning a thermoplastic resin, and the fiber assembly has a median diameter of 1 ⁇ m or less, and the fiber assembly
  • the melt viscosity of the body is 100 mPa ⁇ s or more and 1000 mPa ⁇ s or less.
  • thermoplastic resin that is optimally processed into a powder form or a pellet form is used as a material used for generating the fiber assembly. If the pellet size is too large, for example, when the pellet is supplied using a screw pump (screw extruder) or the like, the pellet may be caught in the groove of the screw. For this reason, when a pellet-shaped thermoplastic resin is used, the pellet size is preferably 5 mm or less.
  • thermoplastic resin for example, a polyolefin resin, a polyester resin, a polyether resin, a polystyrene resin, a polyvinyl resin, a polyamide resin, a polycarbonate resin, Lactic acid resin, engineering plastic, etc. can be used.
  • polyethylene low density polyethylene, high density polyethylene, polypropylene, an ethylene copolymer, a propylene copolymer, a thermoplastic elastomer, or the like is preferably used as a single material or a mixture of a plurality of types.
  • polypropylene resin is particularly preferable because it is easy to lower the melt viscosity and is easily available at a low price.
  • polypropylene resins can easily control the molecular weight during the production process, polypropylenes having various molecular weights are in circulation. In general, the smaller the molecular weight, the higher the price. Therefore, for example, by mixing a resin having a weight average molecular weight of 100,000 or more and a resin having a weight average molecular weight of less than 100,000, The melt viscosity can be effectively adjusted while reducing the amount of the resin component.
  • polypropylene resin examples include homopolymers, block copolymers, random copolymers, etc., and any of them can be used to produce a fiber assembly, but a homopolymer with the highest heat resistance should be used. preferable.
  • the stereoregularity of the crystalline thermoplastic resin may be any of isotactic, syndiotactic, and atactic. However, general isotactic having high stereoregularity is easy to crystallize. Molding shrinkage is small, and heat resistance is also good. Therefore, isotactic is preferable.
  • additives include polyethylene wax, polypropylene wax, hydrocarbon-based, silicone-based, higher alcohol-based and higher fatty acid-based low molecular weight components, phthalate ester-based, phosphate ester-based, fatty acid ester-based, polyester-based additives. , Epoxy type, sulfonic acid amide type and the like.
  • a polypropylene wax which is a wax system.
  • the melt viscosity can be lowered by mixing an appropriate amount of polypropylene wax with polypropylene resin.
  • polypropylene resin and polypropylene wax are similar resins, they have good compatibility.
  • thermoplastic resin examples include benzotriazole, hindered amine, and hydroxyphenyl triazine.
  • examples of the antioxidant include phenolic, phosphite, phosphite, thioether, and amine.
  • the addition amount of the antioxidant may be an appropriate amount, but is preferably 0.2 to 5% by weight, more preferably 0.5 to 1% by weight.
  • the addition amount of the antioxidant is less than the above range, the oxidation suppressing effect is hardly obtained.
  • the addition amount of the antioxidant is larger than the above range, a bleedout in which the antioxidant is precipitated from the fiber surface is caused.
  • a high oxidation resistance effect can be obtained by adding an antioxidant, it is possible to suppress resin coloring and molecular weight reduction due to oxidative decomposition, and to maintain the strength of the resin. Moreover, you may mix multiple types of antioxidant. For example, a synergistic effect can be expected by mixing phenol, phosphide, and thioether.
  • the weight average molecular weight Mw of the thermoplastic resin material is preferably 5,000 or more and 300,000 or less, and more preferably 10,000 or more and 100,000 or less.
  • the weight average molecular weight is less than 10,000, the interaction between the molecules is remarkably reduced. Therefore, the fiber is not fiberized unless the spinning temperature range, the discharge amount, the air volume, etc. are precisely controlled.
  • the weight average molecular weight is less than 5,000, it is no longer fiberized and an aggregate occupying most of the spherical particles.
  • the weight average molecular weight is more than 100,000, the fibers will not become ultrafine fibers unless the thermoplastic resin is heated to a very high temperature and decomposed.
  • the weight average molecular weight exceeds 300,000, it is difficult to extrude from the die itself.
  • the fiber aggregate production method of the present embodiment is a melt spinning method such as a melt blown method, in which a thermoplastic resin is melted and the thermoplastic resin is stretched by blowing high-temperature air to produce ultrafine fibers. .
  • FIG. 1 is a diagram illustrating an example of a fiber generation device 100 of a fiber assembly 202 according to an embodiment.
  • the method for generating a fiber assembly according to the present embodiment is realized by the fiber generation apparatus 100 shown in FIG.
  • the fiber generation device 100 includes a supply unit 111, a heating unit 112, a stretching unit 113, and a collection unit 114.
  • the supply unit 111 includes a quantitative supply machine 101, a hopper 102, a screw pump 103, and a cylinder 105.
  • the heating unit 112 includes a heater 104.
  • the stretching unit 113 includes a resin discharge nozzle 106, an airflow nozzle 107, and a high temperature airflow generation device 402.
  • the collection unit 114 includes a collection body 200 and a nonwoven fabric 201.
  • the fixed amount feeder 101 continuously supplies a solid thermoplastic resin 300 processed into a powder form or a pellet form to the hopper 102 by a certain amount.
  • the backflow of the thermoplastic resin 300 can be suppressed, the discharge amount of the molten resin 400 (the thermoplastic resin 300 melted by heating) from the resin discharge nozzle 106 can be stabilized, and the screw pump The discharge amount of the molten resin 400 can be controlled regardless of the number of rotations 103. Further, supply instability due to the bridge of the thermoplastic resin 300 in the hopper 102 can be suppressed.
  • thermoplastic resin 300 may be charged into the hopper 102 without using the quantitative feeder 101. In that case, heat from the heating unit 112 is transmitted to the hopper 102, and the thermoplastic resin 300 in the hopper 102 is transferred. The thermoplastic resin 300 may flow backward. Therefore, in order to prevent melting of the thermoplastic resin 300 in the hopper 102, it is necessary to sufficiently cool the lower portion of the hopper 102.
  • the screw pump 103 supplies the thermoplastic resin 300 in the hopper 102 to the heating unit 112.
  • the screw pump 103 include, but are not limited to, a single screw full flight screw or a twin screw.
  • the resin melted in the heating unit 112 can be conveyed to the tip of the resin discharge nozzle 106 while kneading different materials by using a twin screw. Is possible.
  • thermoplastic resin 300 when the thermoplastic resin 300 is composed of a single type of material, or even if the thermoplastic resin 300 is composed of a plurality of types of materials, the melt viscosity is low and a large shearing force is required when kneading. If not, a single-axis full flight screw with a simple structure is suitable.
  • a gear pump may be separately installed at the tip of the screw.
  • a cylinder 105 is disposed around the screw pump 103.
  • the diameter of the cylinder 105 is appropriately selected according to the required discharge amount of the molten resin 400.
  • the inner diameter is 20 mm to 60 mm, and the screw length is 10 to 100 mm.
  • thermoplastic resin 300 is formed on the surface of the cylinder 105 in contact with the heater 104. It is easy to melt, and the thermoplastic resin 300 becomes difficult to melt as it goes to the screw pump 103. That is, care should be taken because the thermoplastic resin 300 existing on the surface of the cylinder 105 is supplied with more heat than necessary, and the molecular weight of the thermoplastic resin 300 is likely to decrease.
  • the size of the pellet-shaped thermoplastic resin 300 is at most 5 mm square or less, biting is less likely to occur when the pellets are conveyed by the screw pump 103.
  • the heater 104 is wound around the cylinder 105 and heats the thermoplastic resin 300 being conveyed. As a result, the solid thermoplastic resin 300 is melted and a molten resin 400 is generated.
  • the heating temperature of the heater 104 is set to be equal to or higher than the melting point (hereinafter, simply referred to as “melting point”) of the thermoplastic resin 300, but is preferably set to be 10 ° C. higher than the melting point. The reason is that when the heating temperature of the heater 104 is not higher than the melting point by 10 ° C. or more, the thermoplastic resin 300 is not completely melted and undissolved easily occurs.
  • the heating temperature of the heater 104 is preferably set to be equal to or lower than the thermal decomposition temperature of the thermoplastic resin 300 (hereinafter simply referred to as “thermal decomposition temperature”). The reason is that if the heating temperature of the heater 104 is higher than the thermal decomposition temperature, the thermoplastic resin 300 is vaporized, and a molten resin 400 containing a large amount of bubbles is generated, and the discharge of the molten resin 400 becomes intermittent. This is because short fibers tend to be formed, and the fiber collection rate is reduced.
  • the heating temperature of the heater 104 is preferably set to a temperature at which the oxidation reaction of the thermoplastic resin 300 becomes active (hereinafter referred to as an oxidation reaction activation temperature).
  • an oxidation reaction activation temperature a temperature at which the oxidation reaction of the thermoplastic resin 300 becomes active. The reason is that if the heating temperature of the heater 104 is higher than the oxidation reaction activation temperature, the molecular weight is reduced due to oxidation in the process of heating the thermoplastic resin 300, leading to a decrease in melt viscosity. When the melt viscosity is lowered in the heating unit 112, it becomes difficult to control the melt viscosity to a desired melt viscosity, which causes variations in the discharge amount of the molten resin 400 and variations in the fiber diameter of the ultrafine fibers 500. It is preferable to avoid a decrease in molecular weight.
  • the heating temperature of the heater 104 varies depending on the type of thermoplastic resin used as a raw material. For example, when polypropylene resin is used, the heating temperature of the heater 104 is set to 150 degrees or more and 400 degrees or less. Specifically, the heating temperature of the heater 104 is preferably set to a melting point + 10 ° C. or more and 300 ° C. or less, and more preferably 200 ° C. or more and 300 ° C. or less.
  • the pellets can be completely melted by controlling the time during which the thermoplastic resin stays in the heating unit 112. In addition, when the heating temperature of the heater 104 is set to 200 ° C. or higher, melting can be performed in a shorter time.
  • thermoplastic resin when the heating temperature of the heater 104 is set to a value higher than 400 ° C., the thermoplastic resin easily decomposes even in nitrogen or in a sealed space. In addition, when the heating temperature of the heater 104 is set to a value higher than 300 ° C., oxidative decomposition may occur depending on the atmosphere in which the thermoplastic resin exists and the time in which the heater 104 stays. The time during which the thermoplastic resin stays in the heating unit 112 depends on the temperature profile of the heating unit 112, but if it is set to approximately 1 to 20 minutes, the solid thermoplastic resin 300 is completely melted, and In addition, the decomposition of the thermoplastic resin 300 can be suppressed to a minimum.
  • the molten resin 400 generated by the heating of the heater 104 is supplied to the resin discharge nozzle 106 and is discharged from the resin discharge nozzle 106 in the horizontal direction.
  • the diameter of the resin discharge nozzle 106 is preferably set to 0.1 mm or more and 3 mm or less, and more preferably 0.2 mm or more and 1 mm. It is preferable to set as follows. If the diameter is too small, the pressure in the screw becomes too high, so that the molten resin 400 is likely to leak from the joint of the resin discharge nozzle 106, while if the diameter is too large, it is difficult to make a thin line.
  • the high temperature air flow 401 blows out from the air flow nozzle 107 in the horizontal direction.
  • the hot air stream 401 is generated in the hot air stream generator 402 and supplied to the air stream nozzle 107.
  • the gas used for the generation of the high temperature air flow 401 is, for example, air or nitrogen.
  • the high-temperature airflow generation device 402 compresses air or nitrogen to about 0.1 to 0.5 MPa and passes the airflow nozzle 107 to obtain a high-speed airflow.
  • the high-temperature airflow generation device 402 heats the high-speed airflow passing through the pipe by a torch heater provided inside the airflow nozzle 107. Thereby, the high temperature airflow 401 is produced
  • the case where a torch heater is used has been described as an example, but a heater may be wound around (around) the airflow nozzle 107 and the high-speed airflow may be heated by the heater.
  • the inner diameter of the airflow nozzle 107 is preferably set to 0.1 mm or more and 5 mm or less in order to efficiently generate the high temperature airflow 401.
  • the high temperature air flow 401 can be stably generated without causing clogging due to the molten resin 400 entering the air flow nozzle 107 and solidifying.
  • FIG. 2 is a diagram illustrating a fiber generation process of the fiber assembly 202 according to the embodiment.
  • the airflow nozzle 107 that blows out the high temperature airflow 401 and the resin discharge nozzle 106 that discharges the molten resin 400 are installed at a certain distance.
  • the constant distance is, for example, not less than 0.5 mm and not more than 5 mm. If the distance is too close, the force to pulverize the molten resin 400 tends to work to make short fibers, and if the distance is too far, the molten resin 400 is difficult to be drawn into the high-temperature airflow 401.
  • the airflow nozzle 107 and the resin discharge nozzle 106 are both oriented in the horizontal direction, and the direction in which the high-temperature airflow 401 blows out and the direction in which the molten resin 400 is discharged are parallel to each other.
  • the molten resin 400 discharged from the resin discharge nozzle 106 is gently drawn into the high temperature air flow 401 blown out from the air flow nozzle 107, and is stretched in the horizontal direction to be fiberized. Thereby, as shown in FIG. 1, the ultrafine fiber 500 with a long fiber length is produced
  • the ultrafine fibers 500 generated in the stretching unit 113 are carried in an air stream, collected by the collector 200, and become an ultrafine fiber aggregate 202.
  • the collection body 200 moves at a constant speed, collects the ultrafine fibers 500 conveyed by the airflow with a uniform thickness and weight, and forms a sheet-like uniform fiber assembly 202.
  • the collection body 200 may be a roll or a conveyor, for example.
  • the nonwoven fabric 201 is installed on the surface of the collector 200. This nonwoven fabric 201 makes it easy to collect and handle the fiber assembly 202.
  • the thickness and the weight per unit area of the fiber assembly 202 are determined by the distance from the tip of the resin discharge nozzle 106 to the collection body 200 and the moving speed of the collection body 200.
  • tip of the resin discharge nozzle 106 to the collection body 200 1000 mm or more and 5000 mm or less are preferable. If the distance is too short, the stretching required for fiberization of the molten resin 400 is insufficient, and it becomes difficult to form the ultrafine fiber 500, and the fiber assembly 202 is crushed and easily densified by the pressure of the high-temperature airflow 401. On the other hand, if the distance is too long, the ultrafine fibers 500 do not reach the collection body 200 and the collection becomes difficult. For this reason, the distance from the tip of the resin discharge nozzle 106 to the collector 200 may be set appropriately in accordance with the relationship with the density.
  • the melt viscosity of the fiber assembly is an important factor in melting and spinning thermoplastic resin powders or pellets. This melt viscosity can be verified by heating and melting a fiber assembly composed of spun ultrafine fibers again.
  • the ultrafine fiber here has a fiber diameter distribution, and means that the fiber diameter of the fiber assembly is 1 ⁇ m or less in terms of median diameter. However, a fiber aggregate having a median diameter of 1 ⁇ m or less does not necessarily mean that fibers having a fiber diameter larger than 1 ⁇ m are not included.
  • the fiber assembly of the present embodiment has a median diameter of 1 ⁇ m or less, thereby significantly increasing the surface area, thereby reducing the airflow resistance, improving the adsorption characteristics, and improving the heat insulation performance.
  • Various characteristics such as improved sound absorption characteristics are manifested.
  • 3 to 8 are diagrams showing the melt viscosity characteristics of the fiber assembly according to the embodiment.
  • the horizontal axis indicates the melting temperature
  • the vertical axis indicates the melt viscosity.
  • region shown with an oblique line has shown the preferable condition range (it describes with an ultrafine fiber production
  • the melt viscosity of the fiber assembly is preferably 100 mPa ⁇ s or more and 1000 mPa ⁇ s or less as shown in FIG.
  • the melt viscosity is smaller than the range, the weight average molecular weight Mw of the resin becomes too small, so that the function of intermolecular entanglement is weakened and it is difficult to form a fiber shape. That is, even when the above-described production method (spinning method) is used, the melt resin is easily cut when stretched, so that it is difficult to form a fiber, and instead, an aggregate containing many spherical particles is formed. The strength is significantly reduced.
  • the melt viscosity is larger than the above range, the fiber diameter of the fiber assembly becomes 1 ⁇ m or more, and ultrafine fibers cannot be obtained.
  • the melt viscosity of the fiber assembly is more preferably 100 mPa ⁇ s or more and 1000 mPa ⁇ s or less, with 400 ° C. being the upper limit of the melting temperature, as shown in FIG. If the melting temperature is higher than that range, the thermal decomposition proceeds rapidly even if the resin is blocked from oxygen (for example, nitrogen atmosphere or sealed state), and the weight average molecular weight Mw of the resin decreases. Occurs at the spinning stage. Therefore, for the same reason as described above, it is difficult to form a fiber, and the strength of the produced fiber assembly is also reduced.
  • the melt viscosity of the fiber assembly is 100 mPa ⁇ s or more and 1000 mPa ⁇ s or less, with the temperature lower by 10 ° C. higher than the melting point of the thermoplastic resin as shown in FIG. It is more preferable. If the melting temperature is lower than that range, even if the resin residence time in the heating unit 112 is sufficiently secured, the resin discharge nozzle 106 tends to cause unmelted resin, which causes spinning instability.
  • the melt viscosity of the fiber assembly satisfies the relational expression of 10 11 T ⁇ 3.6 mPa ⁇ s or more and 10 12 T ⁇ 3.6 mPa ⁇ s or less as shown in FIG. More preferably in the melt viscosity range.
  • T indicates the melting temperature of the fiber assembly
  • Y indicates the melt viscosity of the fiber assembly (hereinafter the same in FIGS. 7 and 8).
  • the melt viscosity is lower than this relational expression, ultrafine fibers are produced, but a certain amount of spherical particles are contained, and the strength of the fiber assembly is lowered.
  • the melt viscosity of the fiber assembly is 200 mPa ⁇ s or more and 600 mPa ⁇ s or less, and 2 ⁇ 10 11 T ⁇ 3.6 mPa ⁇ s or more, as shown in FIG. More preferably, it is in a melt viscosity range satisfying the relational expression of 10 12 T ⁇ 3.6 mPa ⁇ s or less.
  • the melt viscosity is lower than this relational expression, although spherical particles are not substantially included, ultrafine fibers having a short fiber length are easily generated, and it is difficult to obtain strength even if the weight of the fiber assembly is increased.
  • the fiber diameter is 0.7 ⁇ m or less, and the characteristics as an ultrafine fiber are improved.
  • the melt viscosity of the fiber assembly is 200 mPa ⁇ s or more and 600 mPa ⁇ s or less in a temperature range of 10 ° C. higher than the melting point of the thermoplastic resin and 350 ° C. or less, as shown in FIG. Further, it is more preferable that the viscosity is in a melt viscosity range satisfying a relational expression of 2 ⁇ 10 11 T ⁇ 3.6 mPa ⁇ s to 10 12 T ⁇ 3.6 mPa ⁇ s.
  • the density of the fiber aggregate is more preferably 0.01 g / cm 3 or more and is 0.040 g / cm 3 or less. A higher quality fiber assembly can be realized.
  • the thickness of the fiber assembly is more preferably larger than 10 mm and smaller than 100 mm.
  • a fiber assembly composed of ultrafine fibers of 1 ⁇ m or less is difficult to maintain a thickness exceeding 10 mm if the strength is low, but by increasing the fiber strength as in this embodiment, the thickness of the fiber assembly can be reduced. Can be maintained.
  • a fiber assembly made of ultrafine fibers of 1 ⁇ m or less and having a thickness exceeding 10 mm can be applied to a wide range of uses such as a sound absorbing material.
  • the fiber assembly is more preferably thicker than 10 mm and thinner than 30 mm.
  • the fiber assembly of the present embodiment has high strength while being a very fine fiber having a median diameter of 1 ⁇ m or less obtained from the fiber diameter distribution.
  • a fiber assembly having a single fiber diameter of 500 nm to 1000 nm and a strength of 1N or more can be obtained (see the examples described later).
  • Example Next, examples of the present disclosure will be described. In addition, a present Example does not limit embodiment of this indication mentioned above. First, items and an evaluation method used when evaluating this example will be described.
  • Fiber diameter (median diameter) Using a scanning electron microscope Phenom G2 pro manufactured by PHENOM-World, 200 fibers were randomly selected from a two-dimensional image of a fiber assembly magnified 10,000 times, and the fiber diameters were measured. The sample was pre-sputtered with Au to prevent charging. Based on the measurement result of the fiber diameter, the median diameter was calculated.
  • Fiber Strength Texture Analyzer TA Manufactured by Stable Micro Systems XT. The tensile strength of the fiber assembly was measured using plus. The sample size was 100 ⁇ 15 mm, and the fiber weight (denoted as w in FIG. 9 described later) was three types: 0.3 g, 0.5 g, and 0.7 g. In the tensile test, the long side direction of the sample was gripped by 20 mm each, the upper end was pulled up in the long side direction at a speed of 1 mm / sec with the lower end fixed, and the maximum strength when the fiber assembly was cut was measured. The measurement result was defined as fiber strength.
  • Weight average molecular weight Mw The weight average molecular weight Mw was measured using Waters high-temperature gel permeation chromatography GPC / V2000. As measurement conditions, the eluent was o-dichlorobenzene, the temperature was 145 ° C., the sample concentration was 1.0 g / L, and the flow rate was 1.0 mL / min. A differential refractometer was used as a detector.
  • a single-axis full flight screw pump was used as the screw pump 103, and the material was conveyed to the heating unit 112.
  • a cylinder 105 having an inner diameter of 20 mm and a length of 100 mm was used.
  • the rotational speed of the screw pump 103 was 5 rpm.
  • the residence time of the molten resin in the heating unit 112 was approximately 10 minutes.
  • a total of five band heaters were installed in the heating unit 112 and set so as to reach the molten resin temperature of each example described later.
  • the diameter of the resin discharge nozzle 106 was 0.5 mm.
  • the compressed air was set to 0.3 MPa, and the high-speed airflow was heated using a torch heater so as to have the temperature of each example described later.
  • the inner diameter of the air nozzle was 1 mm.
  • a roll was used as the collection body 200 to collect the fiber assembly.
  • the outer diameter of the roll was 50 cm, and the rotation speed of the roll was 1 rpm.
  • a nonwoven fabric 201 made of polypropylene and having a basis weight of 20 g / m 2 was installed on the surface of the roll.
  • a melting (spinning) temperature 390 ° C. and a molten resin discharge rate of 3.0 g / min, spinning at an air speed of 50 m / sec and an air temperature of 400 ° C., and collecting the fibers on the nonwoven fabric.
  • An assembly was produced.
  • the molten resin viscosity measured at the melting (spinning) temperature was 200 mPa ⁇ s.
  • the fiber aggregate produced had a fiber diameter of 0.70 ⁇ m, a thickness of 28 mm, a density of 0.016 g / cm 3 , and fiber strengths of 1.0 N, 2.1 N, and 3.2 N, respectively.
  • Mw 48,700, melting point 154 ° C., homopolymer
  • Mw 34,600, melting point 154 ° C., homopolymer
  • the fiber strength of the produced fiber assembly can be as large as 4.5 N, 7.0 N, and 10.0 N, respectively, the obtained fiber diameter is 1.32 ⁇ m, which does not lead to thinning.
  • the fiber assembly had a thickness of 16 mm and a density of 0.029 g / cm 3 .
  • the fiber strength of the produced fiber assembly was as small as 0.2 N at any fiber weight, and a fiber assembly containing many spherical particles was obtained.
  • the fiber diameter was 0.7 ⁇ m.
  • the fiber assembly had a thickness of 10 mm and a density of 0.044 g / cm 3 .
  • FIG. 9 is a diagram showing the characteristics of the fiber assembly 202 of the example and the comparative example according to the embodiment.
  • FIG. 9 collectively shows the above-described Examples 1 to 3 and Comparative Examples 1 to 3.
  • ⁇ means “very good”, a condition that a fiber aggregate having a fiber diameter of 1 ⁇ m or less and a fiber strength of 1.0 N or more was obtained. Is shown. “ ⁇ ” means “good”, and indicates the condition under which a fiber assembly having a fiber diameter of 1 ⁇ m or less was obtained. Further, “x” means “bad”, and indicates the condition under which a fiber aggregate having a fiber diameter of 1 ⁇ m or more was obtained.
  • the fiber assembly of the present disclosure can be applied to a wide range of industrial uses such as a sound absorbing material, a heat insulating material, an adsorbing material, and a filter.

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Abstract

A fiber assembly obtained by melt-spinning a thermoplastic resin, wherein the fiber diameter of the fiber assembly has a median diameter of 1 µm or less, and the melt viscosity of the fiber assembly is 100-1000 mPa∙s.

Description

繊維集合体Fiber assembly
　本開示は、繊維集合体に関する。 The present disclosure relates to a fiber assembly.
　従来、固形の熱可塑性樹脂を溶融し、溶融した熱可塑性樹脂（以下、溶融樹脂という）を熱風により細繊維化して捕集することで、繊維集合体を生成する溶融紡糸法が知られている。この方法では、例えば、溶融樹脂を吐出する手段と、その溶融樹脂に対して熱風を吹き出す手段とを備える繊維生成装置が用いられる。溶融樹脂は熱風により粉砕されて細繊維化し、極細の繊維が生成される。そして、極細の繊維が集積して極細の繊維集合体が生成される。 Conventionally, there has been known a melt spinning method in which a solid thermoplastic resin is melted, and the molten thermoplastic resin (hereinafter referred to as a molten resin) is collected into fine fibers by hot air and collected to produce a fiber assembly. . In this method, for example, a fiber generating device including means for discharging a molten resin and means for blowing hot air to the molten resin is used. The molten resin is pulverized with hot air into fine fibers, and ultrafine fibers are produced. Then, ultrafine fibers are accumulated to produce an ultrafine fiber aggregate.
　このような繊維生成装置では、繊維を効率的に細繊維化するために種々の工夫が施されている。例えば、特許文献１には、溶融樹脂を吐出するノズル孔の両側に熱風を吹き出すための一対のスリットを具備する装置が開示されている。この装置では、各スリットから吹き出された熱風がノズル孔の先端で合流するように構成されており、溶融樹脂の効率的な細繊維化を実現している。 In such a fiber generating device, various devices are provided in order to efficiently make fibers fine. For example, Patent Document 1 discloses an apparatus including a pair of slits for blowing hot air to both sides of a nozzle hole for discharging a molten resin. In this apparatus, the hot air blown out from each slit is configured to merge at the tip of the nozzle hole, thereby realizing efficient fine fiberization of the molten resin.
　しかしながら、特許文献１の技術では、ノズル孔から吐出された繊維状の溶融樹脂に対して直接熱風を吹きつけるため、繊維長が短くなりやすいという問題がある。 However, the technique of Patent Document 1 has a problem that the fiber length tends to be short because hot air is directly blown against the fibrous molten resin discharged from the nozzle holes.
　繊維長が短くなるという問題は、例えば特許文献２、３に開示されている方法により解決することが考えられる。特許文献２には、熱風の平行流に溶融樹脂を載せて延伸させることで、長繊維を得る方法が開示されている。また、特許文献３には、１つの平行な熱風により溶融樹脂を長繊維化する方法が開示されている。 The problem that the fiber length is shortened can be solved by the methods disclosed in Patent Documents 2 and 3, for example. Patent Document 2 discloses a method of obtaining long fibers by placing a molten resin in a parallel flow of hot air and stretching it. Patent Document 3 discloses a method of making a molten resin into a long fiber with one parallel hot air.
　また、溶融樹脂の細繊維化には、熱可塑性樹脂の溶融粘度をでき得る限り小さくすることが必要である。この点で、例えば特許文献４、５には、熱可塑性樹脂の溶融粘度を小さくして溶融樹脂を細繊維化する方法が開示されている。 Also, to make the molten resin finer, it is necessary to reduce the melt viscosity of the thermoplastic resin as much as possible. In this regard, for example, Patent Documents 4 and 5 disclose a method of reducing the melt viscosity of a thermoplastic resin to make the molten resin fine fiber.
特開２０１４－８８６３９号公報JP 2014-88639 A 特開２０１１－２４１５０９号公報JP 2011-241509 A 特許第５３７８９６０号公報Japanese Patent No. 5378960 特開２０１３－１３４４２７号公報JP 2013-134427 A 特許第４５７４２６２号公報Japanese Patent No. 4574262
　しかしながら、特許文献２の技術では、熱風の吹き出し口近傍にて乱流が発生することで、熱風の平行流と反する方向の流れが発生し、紡糸が不安定となるため、繊維集合体の品質に問題が残る。 However, in the technique of Patent Document 2, turbulent flow is generated in the vicinity of the hot air outlet, and thus a flow in a direction opposite to the parallel flow of hot air is generated and spinning becomes unstable. The problem remains.
　また、特許文献３の技術では、溢れ出た溶融樹脂がノズル近傍に付着し固化することで、空気の流れが阻害され、乱流が発生し、紡糸が不安定となるため、繊維集合体の品質に問題が残る。 Further, in the technique of Patent Document 3, since the overflowing molten resin adheres to the vicinity of the nozzle and solidifies, the air flow is inhibited, turbulence is generated, and spinning becomes unstable. Problems with quality remain.
　また、特許文献４、５の技術では、ポリエステル系繊維の使用により強度の高い繊維集合体が得られるものの、平均繊維径が１μｍ以上と大きく、繊維集合体の品質に問題が残る。 Further, in the techniques of Patent Documents 4 and 5, although a fiber assembly having high strength can be obtained by using polyester fibers, the average fiber diameter is as large as 1 μm or more, and the quality of the fiber assembly remains a problem.
　本開示の目的は、上記問題を解決し、極細かつ強度が高い繊維集合体を提供することである。 The purpose of the present disclosure is to solve the above problems and provide a fiber assembly that is extremely fine and has high strength.
　本開示の一態様に係る繊維集合体は、熱可塑性樹脂を溶融紡糸することによって得られる繊維集合体であって、前記繊維集合体の繊維径が１μｍ以下のメジアン径を有し、前記繊維集合体の溶融粘度が１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下である。 A fiber assembly according to an aspect of the present disclosure is a fiber assembly obtained by melt spinning a thermoplastic resin, and the fiber assembly has a median diameter of 1 μm or less, and the fiber assembly The melt viscosity of the body is 100 mPa · s or more and 1000 mPa · s or less.
　本開示によれば、極細かつ強度が高い繊維集合体を提供できる。 According to the present disclosure, it is possible to provide an extremely fine and high strength fiber assembly.
実施の形態に係る繊維集合体の繊維生成装置の一例を示す図である。It is a figure which shows an example of the fiber production | generation apparatus of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の繊維生成過程を示す図である。It is a figure which shows the fiber production | generation process of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施の形態に係る繊維集合体の溶融粘度特性を示す図である。It is a figure which shows the melt viscosity characteristic of the fiber assembly which concerns on embodiment. 実施例および比較例に係る繊維集合体の特性を示す図である。It is a figure which shows the characteristic of the fiber assembly which concerns on an Example and a comparative example.
　以下、本開示の実施の形態について、図面を参照しながら説明する。 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
　（材料）
　まず、本実施の形態の繊維集合体の生成に用いる材料について説明する。 (material)
First, the material used for the production | generation of the fiber assembly of this Embodiment is demonstrated.
　本実施の形態では、繊維集合体の生成に用いる材料として、パウダー状またはペレット状に最適に加工された熱可塑性樹脂を用いる。なお、ペレットサイズが大きすぎると、例えばスクリューポンプ（スクリュー押出機）などを用いてペレットを供給する際に、ペレットがスクリューの溝に噛み込むおそれがある。そのため、ペレット状の熱可塑性樹脂を用いる場合、ペレットサイズを５ｍｍ以下にすることが好ましい。 In this embodiment, a thermoplastic resin that is optimally processed into a powder form or a pellet form is used as a material used for generating the fiber assembly. If the pellet size is too large, for example, when the pellet is supplied using a screw pump (screw extruder) or the like, the pellet may be caught in the groove of the screw. For this reason, when a pellet-shaped thermoplastic resin is used, the pellet size is preferably 5 mm or less.
　熱可塑性樹脂であれば繊維化は可能であるため、本実施の形態では、熱可塑性樹脂として、例えば、ポリオレフィン樹脂、ポリエステル樹脂、ポリエーテル樹脂、ポリスチレン樹脂、ポリビニル樹脂、ポリアミド樹脂、ポリカーボネート樹脂、ポリ乳酸樹脂、エンジニアリングプラスチックなどを用いることができる。 Since fiberization is possible with a thermoplastic resin, in this embodiment, for example, a polyolefin resin, a polyester resin, a polyether resin, a polystyrene resin, a polyvinyl resin, a polyamide resin, a polycarbonate resin, Lactic acid resin, engineering plastic, etc. can be used.
　本実施の形態で生成される繊維集合体の溶融粘度を十分に小さくするためには、例えば、ポリオレフィン系樹脂を用いることが好ましい。具体的には、ポリエチレン、低密度ポリエチレン、高密度ポリエチレン、ポリプロピレン、エチレン共重合体、プロピレン共重合体、熱可塑性エラストマーなどを、単一または複数種類を混合したものを用いることが好ましい。 In order to sufficiently reduce the melt viscosity of the fiber assembly produced in the present embodiment, for example, it is preferable to use a polyolefin resin. Specifically, polyethylene, low density polyethylene, high density polyethylene, polypropylene, an ethylene copolymer, a propylene copolymer, a thermoplastic elastomer, or the like is preferably used as a single material or a mixture of a plurality of types.
　ポリオレフィン系樹脂の中でも、特にポリプロピレン樹脂は、溶融粘度を下げやすく、価格も安く入手しやすいため、好ましい。また、ポリプロピレン樹脂は製造過程で分子量を制御しやすいことから、多種の分子量を持つポリプロピレンが流通している。一般的に、分子量が小さいものほど、価格が高価になることから、例えば、重量平均分子量が１０万以上の樹脂と、重量平均分子量が１０万未満の樹脂とを混ぜ合わせることで、低分子量の樹脂成分の量を減らしながら、有効的に溶融粘度を調整することができる。 Among polyolefin resins, polypropylene resin is particularly preferable because it is easy to lower the melt viscosity and is easily available at a low price. In addition, since polypropylene resins can easily control the molecular weight during the production process, polypropylenes having various molecular weights are in circulation. In general, the smaller the molecular weight, the higher the price. Therefore, for example, by mixing a resin having a weight average molecular weight of 100,000 or more and a resin having a weight average molecular weight of less than 100,000, The melt viscosity can be effectively adjusted while reducing the amount of the resin component.
　ポリプロピレン樹脂としては、例えば、ホモポリマー、ブロックコポリマー、ランダムコポリマーなどが挙げられ、それらのどれを用いても繊維集合体を生成することができるが、最も耐熱性に優れたホモポリマーを用いることが好ましい。また、結晶性熱可塑性樹脂の立体規則性は、アイソタクチック、シンジオタクチック、アタクチックのいずれであってもよいが、一般的でかつ立体規則性が高いアイソタクチックは、結晶化しやすいことから成形収縮が小さく、また、耐熱性も良好である。よって、アイソタクチックが好ましい。 Examples of the polypropylene resin include homopolymers, block copolymers, random copolymers, etc., and any of them can be used to produce a fiber assembly, but a homopolymer with the highest heat resistance should be used. preferable. In addition, the stereoregularity of the crystalline thermoplastic resin may be any of isotactic, syndiotactic, and atactic. However, general isotactic having high stereoregularity is easy to crystallize. Molding shrinkage is small, and heat resistance is also good. Therefore, isotactic is preferable.
　また、熱可塑性樹脂に可塑剤や滑剤などの添加剤を加えることにより、より溶融粘度を低下させることが可能である。添加剤としては、例えば、ポリエチレンワックス、ポリプロピレンワックス、炭化水素系、シリコーン系、高級アルコール系、高級脂肪酸系などの低分子量成分や、フタル酸エステル系やリン酸エステル系、脂肪酸エステル系、ポリエステル系、エポキシ系、スルホン酸アミド系などが挙げられる。特に、ワックス系であるポリプロピレンワックスを用いることが好ましい。例えば、ポリプロピレン樹脂にポリプロピレンワックスを適量混ぜ合わせることにより、溶融粘度を低下させることができる。また、ポリプロピレン樹脂とポリプロピレンワックスは同類の樹脂であるため、相溶性が良い。 Also, it is possible to further lower the melt viscosity by adding an additive such as a plasticizer or a lubricant to the thermoplastic resin. Examples of additives include polyethylene wax, polypropylene wax, hydrocarbon-based, silicone-based, higher alcohol-based and higher fatty acid-based low molecular weight components, phthalate ester-based, phosphate ester-based, fatty acid ester-based, polyester-based additives. , Epoxy type, sulfonic acid amide type and the like. In particular, it is preferable to use a polypropylene wax which is a wax system. For example, the melt viscosity can be lowered by mixing an appropriate amount of polypropylene wax with polypropylene resin. Also, since polypropylene resin and polypropylene wax are similar resins, they have good compatibility.
　また、熱可塑性樹脂に紫外線吸収剤や酸化防止剤といった添加剤を含有させることにより、繊維集合体の耐熱劣化や経時劣化を抑制することが期待できる。紫外線吸収剤としては、例えば、ベンゾトリアゾール系やヒンダードアミン系、ヒドロキシフェニルトリアジン系などが挙げられる。また、酸化防止剤としては、例えば、フェノール系、亜リン酸エステル系、ホスファイト系、チオエーテル系、アミン系などが挙げられる。 In addition, it is expected that the heat resistance deterioration and the deterioration with time of the fiber assembly are suppressed by adding an additive such as an ultraviolet absorber or an antioxidant to the thermoplastic resin. Examples of the ultraviolet absorber include benzotriazole, hindered amine, and hydroxyphenyl triazine. Examples of the antioxidant include phenolic, phosphite, phosphite, thioether, and amine.
　酸化防止剤の添加量は、適量でよいが、好ましくは０．２以上５重量％以下、より好ましくは、０．５以上１重量％以下である。酸化防止剤の添加量が上記範囲より少ないと、酸化抑制効果が得られにくくなる。その一方、酸化防止剤の添加量が上記範囲より多いと、繊維表面から酸化防止剤が析出するブリードアウトを引き起こす。 The addition amount of the antioxidant may be an appropriate amount, but is preferably 0.2 to 5% by weight, more preferably 0.5 to 1% by weight. When the addition amount of the antioxidant is less than the above range, the oxidation suppressing effect is hardly obtained. On the other hand, when the addition amount of the antioxidant is larger than the above range, a bleedout in which the antioxidant is precipitated from the fiber surface is caused.
　酸化防止剤を添加することで、高い耐酸化効果が得られることから、樹脂の着色や、酸化分解による分子量の低下を抑制し、樹脂の強度を維持することができる。また、酸化防止剤を複数種混合してもよい。例えば、フェノール系とホスファイド系とチオエーテル系を混合することで、相乗効果を期待できる。 Since a high oxidation resistance effect can be obtained by adding an antioxidant, it is possible to suppress resin coloring and molecular weight reduction due to oxidative decomposition, and to maintain the strength of the resin. Moreover, you may mix multiple types of antioxidant. For example, a synergistic effect can be expected by mixing phenol, phosphide, and thioether.
　また、熱可塑性樹脂材料の重量平均分子量Ｍｗは、５，０００以上３００，０００以下であることが好ましく、さらには、１０，０００以上１００，０００以下であることがより好ましい。重量平均分子量が１０，０００未満になると、分子同士の相互作用が著しく低下するため、紡糸温度範囲、吐出量、風量などを精密に制御しないと繊維化しない。さらに、重量平均分子量が５，０００未満になると、もはや繊維化せず、球状粒子が大半を占める集合体となってしまう。また、重量平均分子量が１００，０００より多くなると、熱可塑性樹脂をかなり高温にまで昇温させて分解させなければ、極細繊維にならない。さらに、重量平均分子量が３００，０００より多くなると、口金から押し出すこと自体が困難になる。 Further, the weight average molecular weight Mw of the thermoplastic resin material is preferably 5,000 or more and 300,000 or less, and more preferably 10,000 or more and 100,000 or less. When the weight average molecular weight is less than 10,000, the interaction between the molecules is remarkably reduced. Therefore, the fiber is not fiberized unless the spinning temperature range, the discharge amount, the air volume, etc. are precisely controlled. Furthermore, when the weight average molecular weight is less than 5,000, it is no longer fiberized and an aggregate occupying most of the spherical particles. On the other hand, if the weight average molecular weight is more than 100,000, the fibers will not become ultrafine fibers unless the thermoplastic resin is heated to a very high temperature and decomposed. Furthermore, when the weight average molecular weight exceeds 300,000, it is difficult to extrude from the die itself.
　（繊維集合体の生成方法）
　次に、上述した熱可塑性樹脂を用いて繊維集合体を生成する方法について説明する。 (Method for producing fiber assembly)
Next, a method for generating a fiber assembly using the above-described thermoplastic resin will be described.
　本実施の形態の繊維集合体の生成方法は、例えばメルトブローン法のような、熱可塑性樹脂を溶融させ、高温エアーを吹き付けることによって熱可塑性樹脂を延伸させ、極細繊維を生成する溶融紡糸法である。 The fiber aggregate production method of the present embodiment is a melt spinning method such as a melt blown method, in which a thermoplastic resin is melted and the thermoplastic resin is stretched by blowing high-temperature air to produce ultrafine fibers. .
　図１は、実施の形態に係る繊維集合体２０２の繊維生成装置１００の一例を示す図である。 FIG. 1 is a diagram illustrating an example of a fiber generation device 100 of a fiber assembly 202 according to an embodiment.
　本実施の形態の繊維集合体の生成方法は、図１に示す繊維生成装置１００により実現される。 The method for generating a fiber assembly according to the present embodiment is realized by the fiber generation apparatus 100 shown in FIG.
　図１に示すように、繊維生成装置１００は、供給部１１１、加熱部１１２、延伸部１１３、捕集部１１４を備える。供給部１１１は、定量供給機１０１、ホッパー１０２、スクリューポンプ１０３、シリンダー１０５を有する。加熱部１１２は、ヒーター１０４を有する。延伸部１１３は、樹脂吐出ノズル１０６、気流ノズル１０７、高温気流生成装置４０２を有する。捕集部１１４は、捕集体２００、不織布２０１を有する。 1, the fiber generation device 100 includes a supply unit 111, a heating unit 112, a stretching unit 113, and a collection unit 114. The supply unit 111 includes a quantitative supply machine 101, a hopper 102, a screw pump 103, and a cylinder 105. The heating unit 112 includes a heater 104. The stretching unit 113 includes a resin discharge nozzle 106, an airflow nozzle 107, and a high temperature airflow generation device 402. The collection unit 114 includes a collection body 200 and a nonwoven fabric 201.
　まず、定量供給機１０１は、パウダー状またはペレット状に加工された固形の熱可塑性樹脂３００をホッパー１０２へ一定量ずつ継続供給する。定量供給機１０１を用いることにより、熱可塑性樹脂３００の逆流を抑制でき、樹脂吐出ノズル１０６からの溶融樹脂４００（加熱により溶融した熱可塑性樹脂３００）の吐出量を安定させることができ、スクリューポンプ１０３の回転数に関わらず溶融樹脂４００の吐出量を制御できる。また、ホッパー１０２内での熱可塑性樹脂３００がブリッジすることによる供給不安定性を抑制することもできる。 First, the fixed amount feeder 101 continuously supplies a solid thermoplastic resin 300 processed into a powder form or a pellet form to the hopper 102 by a certain amount. By using the fixed amount feeder 101, the backflow of the thermoplastic resin 300 can be suppressed, the discharge amount of the molten resin 400 (the thermoplastic resin 300 melted by heating) from the resin discharge nozzle 106 can be stabilized, and the screw pump The discharge amount of the molten resin 400 can be controlled regardless of the number of rotations 103. Further, supply instability due to the bridge of the thermoplastic resin 300 in the hopper 102 can be suppressed.
　なお、定量供給機１０１を用いずに、熱可塑性樹脂３００をホッパー１０２へ投入してもよいが、その場合、加熱部１１２からの熱がホッパー１０２に伝わって、ホッパー１０２内の熱可塑性樹脂３００を溶融し、熱可塑性樹脂３００が逆流してしまうおそれがある。よって、ホッパー１０２内の熱可塑性樹脂３００の溶融を防ぐため、ホッパー１０２の下方を十分に冷却しておく必要がある。 Note that the thermoplastic resin 300 may be charged into the hopper 102 without using the quantitative feeder 101. In that case, heat from the heating unit 112 is transmitted to the hopper 102, and the thermoplastic resin 300 in the hopper 102 is transferred. The thermoplastic resin 300 may flow backward. Therefore, in order to prevent melting of the thermoplastic resin 300 in the hopper 102, it is necessary to sufficiently cool the lower portion of the hopper 102.
　次に、スクリューポンプ１０３は、ホッパー１０２内の熱可塑性樹脂３００を加熱部１１２へ供給する。スクリューポンプ１０３としては、例えば、単軸フルフライトスクリューまたは二軸スクリューが挙げられるが、これらに限定されない。 Next, the screw pump 103 supplies the thermoplastic resin 300 in the hopper 102 to the heating unit 112. Examples of the screw pump 103 include, but are not limited to, a single screw full flight screw or a twin screw.
　熱可塑性樹脂３００が複数種類の材料で構成されている場合、二軸スクリューを用いることで、異なる材料を混練しながら、加熱部１１２において溶融した樹脂を樹脂吐出ノズル１０６の先端まで搬送することが可能である。 When the thermoplastic resin 300 is composed of a plurality of types of materials, the resin melted in the heating unit 112 can be conveyed to the tip of the resin discharge nozzle 106 while kneading different materials by using a twin screw. Is possible.
　一方、熱可塑性樹脂３００が単一種の材料で構成されている場合、または、熱可塑性樹脂３００が複数種類の材料で構成されていても、溶融粘度が低く、混練する際に大きなせん断力を必要としない場合、シンプルな構造である単軸フルフライトスクリューが適している。 On the other hand, when the thermoplastic resin 300 is composed of a single type of material, or even if the thermoplastic resin 300 is composed of a plurality of types of materials, the melt viscosity is low and a large shearing force is required when kneading. If not, a single-axis full flight screw with a simple structure is suitable.
　さらに、溶融樹脂の吐出精度を高める必要や、溶融粘度の高い溶融樹脂を押し出す必要がある場合は、スクリューの先端にギアポンプを別途設置してもよい。 Furthermore, when it is necessary to increase the discharge accuracy of the molten resin or to extrude a molten resin having a high melt viscosity, a gear pump may be separately installed at the tip of the screw.
　スクリューポンプ１０３の周囲には、シリンダー１０５が配置されている。シリンダー１０５の径は、要求される溶融樹脂４００の吐出量に応じて適宜選択されるが、一般的には、例えば、内径は２０ｍｍ～６０ｍｍ、スクリュー長は１０～１００ｍｍである。シリンダー１０５の内径を大きくすることで、溶融樹脂４００の吐出能力を大きくすることが可能である。 A cylinder 105 is disposed around the screw pump 103. The diameter of the cylinder 105 is appropriately selected according to the required discharge amount of the molten resin 400. In general, for example, the inner diameter is 20 mm to 60 mm, and the screw length is 10 to 100 mm. By increasing the inner diameter of the cylinder 105, the discharge capacity of the molten resin 400 can be increased.
　ただし、シリンダー１０５の内径を大きくしすぎると、図１に示すようにシリンダー１０５の回りにヒーター１０４を巻き付けてシリンダー１０５全体を加熱する場合、ヒーター１０４に接するシリンダー１０５の表面において熱可塑性樹脂３００が溶融しやすく、スクリューポンプ１０３に向かうほど熱可塑性樹脂３００が溶融しづらくなる。すなわち、シリンダー１０５の表面に存在する熱可塑性樹脂３００には必要以上に熱が供給され、熱可塑性樹脂３００の分子量の低下が発生しやすくなるので、注意が必要である。ペレット状の熱可塑性樹脂３００のサイズを大きくとも５ｍｍ角以下にすることで、スクリューポンプ１０３で搬送する際に噛み込みが発生しにくくなる。 However, if the inner diameter of the cylinder 105 is made too large, as shown in FIG. 1, when the heater 104 is wound around the cylinder 105 to heat the entire cylinder 105, the thermoplastic resin 300 is formed on the surface of the cylinder 105 in contact with the heater 104. It is easy to melt, and the thermoplastic resin 300 becomes difficult to melt as it goes to the screw pump 103. That is, care should be taken because the thermoplastic resin 300 existing on the surface of the cylinder 105 is supplied with more heat than necessary, and the molecular weight of the thermoplastic resin 300 is likely to decrease. When the size of the pellet-shaped thermoplastic resin 300 is at most 5 mm square or less, biting is less likely to occur when the pellets are conveyed by the screw pump 103.
　ヒーター１０４は、シリンダー１０５の周囲に巻き付けられており、搬送される熱可塑性樹脂３００を加熱する。これにより、固形の熱可塑性樹脂３００は溶融し、溶融樹脂４００が生成される。 The heater 104 is wound around the cylinder 105 and heats the thermoplastic resin 300 being conveyed. As a result, the solid thermoplastic resin 300 is melted and a molten resin 400 is generated.
　ヒーター１０４の加熱温度は、熱可塑性樹脂３００の融点（以下、単に「融点」という）以上に設定されることが必須であるが、融点より１０℃以上高く設定されることが好ましい。その理由は、ヒーター１０４の加熱温度が融点より１０℃以上高くない場合、熱可塑性樹脂３００は完全に溶融しきらず、溶け残りが発生しやすくなるためである。 It is essential that the heating temperature of the heater 104 is set to be equal to or higher than the melting point (hereinafter, simply referred to as “melting point”) of the thermoplastic resin 300, but is preferably set to be 10 ° C. higher than the melting point. The reason is that when the heating temperature of the heater 104 is not higher than the melting point by 10 ° C. or more, the thermoplastic resin 300 is not completely melted and undissolved easily occurs.
　また、ヒーター１０４の加熱温度は、熱可塑性樹脂３００の熱分解温度（以下、単に「熱分解温度」という）以下に設定されることが好ましい。その理由は、ヒーター１０４の加熱温度が熱分解温度より高いと、熱可塑性樹脂３００が気化して、気泡を多く含んだ溶融樹脂４００が生成され、溶融樹脂４００の吐出が間欠的となってしまい、短繊維になり易いためであり、また、繊維の収集率が低下するためである。 Also, the heating temperature of the heater 104 is preferably set to be equal to or lower than the thermal decomposition temperature of the thermoplastic resin 300 (hereinafter simply referred to as “thermal decomposition temperature”). The reason is that if the heating temperature of the heater 104 is higher than the thermal decomposition temperature, the thermoplastic resin 300 is vaporized, and a molten resin 400 containing a large amount of bubbles is generated, and the discharge of the molten resin 400 becomes intermittent. This is because short fibers tend to be formed, and the fiber collection rate is reduced.
　また、ヒーター１０４の加熱温度は、熱可塑性樹脂３００の酸化反応が活性となる温度（以下、酸化反応活性温度という）以下に設定されることが好ましい。その理由は、ヒーター１０４の加熱温度が酸化反応活性温度より高いと、熱可塑性樹脂３００を加熱する過程で酸化による分子量低下が起こり、溶融粘度の低下につながるためである。溶融粘度が加熱部１１２で低下すると、所望の溶融粘度に制御することが困難となり、溶融樹脂４００の吐出量のバラツキや、極細繊維５００の繊維径のバラツキを引き起こしてしまうため、加熱部１１２における分子量の低下は、回避することが好ましい。 Also, the heating temperature of the heater 104 is preferably set to a temperature at which the oxidation reaction of the thermoplastic resin 300 becomes active (hereinafter referred to as an oxidation reaction activation temperature). The reason is that if the heating temperature of the heater 104 is higher than the oxidation reaction activation temperature, the molecular weight is reduced due to oxidation in the process of heating the thermoplastic resin 300, leading to a decrease in melt viscosity. When the melt viscosity is lowered in the heating unit 112, it becomes difficult to control the melt viscosity to a desired melt viscosity, which causes variations in the discharge amount of the molten resin 400 and variations in the fiber diameter of the ultrafine fibers 500. It is preferable to avoid a decrease in molecular weight.
　ヒーター１０４の加熱温度は、原料として用いる熱可塑性樹脂の種類によって異なる。例えば、ポリプロピレン樹脂を使用する場合、ヒーター１０４の加熱温度は、１５０度以上かつ４００度以下に設定される。具体的には、ヒーター１０４の加熱温度は、融点＋１０℃以上３００℃以下に設定されることが好ましく、２００℃以上３００℃以下に設定されることがより好ましい。 The heating temperature of the heater 104 varies depending on the type of thermoplastic resin used as a raw material. For example, when polypropylene resin is used, the heating temperature of the heater 104 is set to 150 degrees or more and 400 degrees or less. Specifically, the heating temperature of the heater 104 is preferably set to a melting point + 10 ° C. or more and 300 ° C. or less, and more preferably 200 ° C. or more and 300 ° C. or less.
　ヒーター１０４の加熱温度を融点＋１０℃以上に設定した場合、熱可塑性樹脂が加熱部１１２に滞留する時間を制御することで、ペレットを完全に溶融させることが可能である。また、ヒーター１０４の加熱温度を２００℃以上に設定した場合、より短時間で溶融させることが可能になる。 When the heating temperature of the heater 104 is set to the melting point + 10 ° C. or higher, the pellets can be completely melted by controlling the time during which the thermoplastic resin stays in the heating unit 112. In addition, when the heating temperature of the heater 104 is set to 200 ° C. or higher, melting can be performed in a shorter time.
　また、ヒーター１０４の加熱温度を４００℃より高い値に設定した場合、熱可塑性樹脂が窒素や密閉空間内においても、容易に熱分解が発生してしまう。また、ヒーター１０４の加熱温度を３００℃より高い値に設定した場合、熱可塑性樹脂が存在する雰囲気や加熱部１１２に滞留する時間によっては、酸化分解が発生する可能性がある。熱可塑性樹脂が加熱部１１２に滞留する時間は、加熱部１１２の温度プロファイルによっても左右されるが、概ね、１～２０分程度で設定すると、固形の熱可塑性樹脂３００を完全に溶融させ、かつ、熱可塑性樹脂３００の分解を最小限に抑制することができる。 In addition, when the heating temperature of the heater 104 is set to a value higher than 400 ° C., the thermoplastic resin easily decomposes even in nitrogen or in a sealed space. In addition, when the heating temperature of the heater 104 is set to a value higher than 300 ° C., oxidative decomposition may occur depending on the atmosphere in which the thermoplastic resin exists and the time in which the heater 104 stays. The time during which the thermoplastic resin stays in the heating unit 112 depends on the temperature profile of the heating unit 112, but if it is set to approximately 1 to 20 minutes, the solid thermoplastic resin 300 is completely melted, and In addition, the decomposition of the thermoplastic resin 300 can be suppressed to a minimum.
　ヒーター１０４の加熱により生成された溶融樹脂４００は、樹脂吐出ノズル１０６に供給され、樹脂吐出ノズル１０６から水平方向に吐出される。 The molten resin 400 generated by the heating of the heater 104 is supplied to the resin discharge nozzle 106 and is discharged from the resin discharge nozzle 106 in the horizontal direction.
　樹脂吐出ノズル１０６の形状に制限はないが、例えば形状を円形とした場合、樹脂吐出ノズル１０６の直径は、０．１ｍｍ以上３ｍｍ以下に設定されることが好ましく、さらには、０．２ｍｍ以上１ｍｍ以下に設定されることが好ましい。直径が小さすぎると、スクリュー内の圧力が高くなりすぎるため、樹脂吐出ノズル１０６のつなぎ目から溶融樹脂４００が漏れやすくなる一方で、直径が大きすぎると、細線化しづらい。 Although the shape of the resin discharge nozzle 106 is not limited, for example, when the shape is circular, the diameter of the resin discharge nozzle 106 is preferably set to 0.1 mm or more and 3 mm or less, and more preferably 0.2 mm or more and 1 mm. It is preferable to set as follows. If the diameter is too small, the pressure in the screw becomes too high, so that the molten resin 400 is likely to leak from the joint of the resin discharge nozzle 106, while if the diameter is too large, it is difficult to make a thin line.
　樹脂吐出ノズル１０６からの溶融樹脂４００の吐出と同時に、または、樹脂吐出ノズル１０６からの溶融樹脂４００の吐出前において、気流ノズル１０７からは、高温気流４０１が水平方向に吹き出す。 Simultaneously with the discharge of the molten resin 400 from the resin discharge nozzle 106 or before the discharge of the molten resin 400 from the resin discharge nozzle 106, the high temperature air flow 401 blows out from the air flow nozzle 107 in the horizontal direction.
　高温気流４０１は、高温気流生成装置４０２において生成され、気流ノズル１０７へ供給される。高温気流４０１の生成に用いられる気体は、例えば、空気や窒素などである。高温気流生成装置４０２は、まず、空気や窒素を０．１～０．５ＭＰａ程度に圧縮して気流ノズル１０７を通過させ、高速気流を得る。次に、高温気流生成装置４０２は、気流ノズル１０７の内部に設けられたトーチヒーターにより、配管内を通過する高速気流を加熱する。これにより、高温気流４０１が生成される。なお、上記説明では、トーチヒーターを用いる場合を例に挙げたが、気流ノズル１０７の外部（周囲）にヒーターを巻き付け、そのヒーターにより高速気流を加熱してもよい。 The hot air stream 401 is generated in the hot air stream generator 402 and supplied to the air stream nozzle 107. The gas used for the generation of the high temperature air flow 401 is, for example, air or nitrogen. First, the high-temperature airflow generation device 402 compresses air or nitrogen to about 0.1 to 0.5 MPa and passes the airflow nozzle 107 to obtain a high-speed airflow. Next, the high-temperature airflow generation device 402 heats the high-speed airflow passing through the pipe by a torch heater provided inside the airflow nozzle 107. Thereby, the high temperature airflow 401 is produced | generated. In the above description, the case where a torch heater is used has been described as an example, but a heater may be wound around (around) the airflow nozzle 107 and the high-speed airflow may be heated by the heater.
　気流ノズル１０７の内径は、高温気流４０１を効率良く生成するために、０．１ｍｍ以上５ｍｍ以下に設定されることが好ましい。溶融樹脂４００が気流ノズル１０７内に進入して固化することによる詰まりを発生させることなく、安定的に高温気流４０１を生成することが可能となる。 The inner diameter of the airflow nozzle 107 is preferably set to 0.1 mm or more and 5 mm or less in order to efficiently generate the high temperature airflow 401. The high temperature air flow 401 can be stably generated without causing clogging due to the molten resin 400 entering the air flow nozzle 107 and solidifying.
　図２は、実施の形態に係る繊維集合体２０２の繊維生成過程を示す図である。 FIG. 2 is a diagram illustrating a fiber generation process of the fiber assembly 202 according to the embodiment.
　図２に示すように、高温気流４０１を吹き出す気流ノズル１０７と溶融樹脂４００を吐出する樹脂吐出ノズル１０６とは、一定距離を隔てて設置されている。一定距離は、例えば、０．５ｍｍ以上５ｍｍ以下である。距離が近すぎると、溶融樹脂４００を粉砕する力が働いて短繊維化しやすく、距離が遠すぎると、溶融樹脂４００が高温気流４０１に引き込まれにくくなる。また、図２に示すように、気流ノズル１０７と樹脂吐出ノズル１０６はともに水平方向を向いており、高温気流４０１の吹き出す方向と溶融樹脂４００が吐出する方向とが互いに平行である。 As shown in FIG. 2, the airflow nozzle 107 that blows out the high temperature airflow 401 and the resin discharge nozzle 106 that discharges the molten resin 400 are installed at a certain distance. The constant distance is, for example, not less than 0.5 mm and not more than 5 mm. If the distance is too close, the force to pulverize the molten resin 400 tends to work to make short fibers, and if the distance is too far, the molten resin 400 is difficult to be drawn into the high-temperature airflow 401. As shown in FIG. 2, the airflow nozzle 107 and the resin discharge nozzle 106 are both oriented in the horizontal direction, and the direction in which the high-temperature airflow 401 blows out and the direction in which the molten resin 400 is discharged are parallel to each other.
　そして、図２に示すように、樹脂吐出ノズル１０６から吐出された溶融樹脂４００は、気流ノズル１０７から吹き出した高温気流４０１に緩やかに引き込まれ、水平方向に延伸されて繊維化する。これにより、図１に示すように、繊維長の長い極細繊維５００が生成される。 Then, as shown in FIG. 2, the molten resin 400 discharged from the resin discharge nozzle 106 is gently drawn into the high temperature air flow 401 blown out from the air flow nozzle 107, and is stretched in the horizontal direction to be fiberized. Thereby, as shown in FIG. 1, the ultrafine fiber 500 with a long fiber length is produced | generated.
　このようにして、本実施の形態では、溶融粘度の低い樹脂を用いても、垂れることなく安定的に長繊維を生成することができる。なお、例えば、極めて小さい溶融粘度の樹脂を鉛直下向きのノズルから吐出する場合、重力により垂れやすくなるので、溶融樹脂の吐出量制御が困難になる。 Thus, in this embodiment, even if a resin having a low melt viscosity is used, long fibers can be stably generated without dripping. Note that, for example, when a resin having a very low melt viscosity is discharged from a vertically downward nozzle, it tends to sag due to gravity, making it difficult to control the discharge amount of the molten resin.
　延伸部１１３にて生成された極細繊維５００は、気流に載って運ばれ、捕集体２００により捕集され、極細の繊維集合体２０２となる。捕集体２００は一定速度で動いており、気流により搬送される極細繊維５００を均一な厚み、重量にて捕集し、シート状の均一な繊維集合体２０２を形成する。捕集体２００は、例えば、ロールであっても、コンベアであってもよい。 The ultrafine fibers 500 generated in the stretching unit 113 are carried in an air stream, collected by the collector 200, and become an ultrafine fiber aggregate 202. The collection body 200 moves at a constant speed, collects the ultrafine fibers 500 conveyed by the airflow with a uniform thickness and weight, and forms a sheet-like uniform fiber assembly 202. The collection body 200 may be a roll or a conveyor, for example.
　また、捕集体２００の表面には不織布２０１が設置されている。この不織布２０１により、繊維集合体２０２を、回収しやすく、かつ、ハンドリングしやすくなる。 Moreover, the nonwoven fabric 201 is installed on the surface of the collector 200. This nonwoven fabric 201 makes it easy to collect and handle the fiber assembly 202.
　繊維集合体２０２の厚みおよび単位面積当たりの重量は、樹脂吐出ノズル１０６の先端から捕集体２００までの距離と、捕集体２００の移動速度とにより決まる。樹脂吐出ノズル１０６の先端から捕集体２００までの距離は、１０００ｍｍ以上５０００ｍｍ以下が好ましい。距離が短すぎると、溶融樹脂４００の繊維化に必要な延伸が足りず、極細繊維５００が形成されにくくなり、また、高温気流４０１の圧力により、繊維集合体２０２がつぶれて高密度化しやすい。逆に、距離が長すぎると、極細繊維５００が捕集体２００まで届かず、捕集が困難になる。このような理由により、樹脂吐出ノズル１０６の先端から捕集体２００までの距離は、密度との関係に合わせて、適切に設定するとよい。 The thickness and the weight per unit area of the fiber assembly 202 are determined by the distance from the tip of the resin discharge nozzle 106 to the collection body 200 and the moving speed of the collection body 200. As for the distance from the front-end | tip of the resin discharge nozzle 106 to the collection body 200, 1000 mm or more and 5000 mm or less are preferable. If the distance is too short, the stretching required for fiberization of the molten resin 400 is insufficient, and it becomes difficult to form the ultrafine fiber 500, and the fiber assembly 202 is crushed and easily densified by the pressure of the high-temperature airflow 401. On the other hand, if the distance is too long, the ultrafine fibers 500 do not reach the collection body 200 and the collection becomes difficult. For this reason, the distance from the tip of the resin discharge nozzle 106 to the collector 200 may be set appropriately in accordance with the relationship with the density.
　（繊維集合体）
　次に、上述した生成方法により生成された繊維集合体について説明する。 (Fiber assembly)
Next, the fiber assembly produced | generated by the production | generation method mentioned above is demonstrated.
　繊維集合体の溶融粘度は、熱可塑性樹脂のパウダーまたはペレットを溶融し、紡糸する際の重要な因子である。この溶融粘度は、紡糸された極細繊維から成る繊維集合体を再度加熱して溶融することで検証することができる。ここでいう極細繊維とは、繊維径の分布を有し、繊維集合体の繊維径がメジアン径で１μｍ以下であることを意味している。ただし、メジアン径で１μｍ以下の繊維集合体とは、必ずしも、１μｍより大きな繊維径の繊維を含まないということではない。 The melt viscosity of the fiber assembly is an important factor in melting and spinning thermoplastic resin powders or pellets. This melt viscosity can be verified by heating and melting a fiber assembly composed of spun ultrafine fibers again. The ultrafine fiber here has a fiber diameter distribution, and means that the fiber diameter of the fiber assembly is 1 μm or less in terms of median diameter. However, a fiber aggregate having a median diameter of 1 μm or less does not necessarily mean that fibers having a fiber diameter larger than 1 μm are not included.
　このように、本実施の形態の繊維集合体は、繊維径が１μｍ以下のメジアン径を有することで、表面積が格段に大きくなるため、通気抵抗の減少、吸着特性の向上、断熱性能の向上、吸音特性の向上など、様々な特性が発現する。 As described above, the fiber assembly of the present embodiment has a median diameter of 1 μm or less, thereby significantly increasing the surface area, thereby reducing the airflow resistance, improving the adsorption characteristics, and improving the heat insulation performance. Various characteristics such as improved sound absorption characteristics are manifested.
　図３から図８は、実施の形態に係る繊維集合体の溶融粘度特性を示す図である。 3 to 8 are diagrams showing the melt viscosity characteristics of the fiber assembly according to the embodiment.
　図３から図８において、横軸は溶融温度を示し、縦軸は溶融粘度を示している。そして、斜線で示す領域は、極細繊維から成る繊維集合体を得るために好ましい条件範囲（図３から図８において、極細繊維生成領域と表記する）を示している。 3 to 8, the horizontal axis indicates the melting temperature, and the vertical axis indicates the melt viscosity. And the area | region shown with an oblique line has shown the preferable condition range (it describes with an ultrafine fiber production | generation area | region in FIGS. 3-8) in order to obtain the fiber assembly which consists of an ultrafine fiber.
　本実施の形態において、繊維集合体の溶融粘度は、図３に示すように、１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下であることが好ましい。その範囲よりも溶融粘度が小さいと、樹脂の重量平均分子量Ｍｗが小さくなりすぎるため、分子同士のからみ合う作用が弱くなり、繊維としての形が形成されにくい。すなわち、上述した生成方法（紡糸方法）をもってしても溶融樹脂を延伸する際に切れが生じ易いため、繊維に成りにくく、代わりに球状粒子を多く含む集合体になってしまい、繊維集合体の強度が著しく低下する。また、上述した範囲よりも溶融粘度が大きいと、繊維集合体の繊維径が１μｍ以上になり、極細繊維が得られない。 In the present embodiment, the melt viscosity of the fiber assembly is preferably 100 mPa · s or more and 1000 mPa · s or less as shown in FIG. When the melt viscosity is smaller than the range, the weight average molecular weight Mw of the resin becomes too small, so that the function of intermolecular entanglement is weakened and it is difficult to form a fiber shape. That is, even when the above-described production method (spinning method) is used, the melt resin is easily cut when stretched, so that it is difficult to form a fiber, and instead, an aggregate containing many spherical particles is formed. The strength is significantly reduced. On the other hand, if the melt viscosity is larger than the above range, the fiber diameter of the fiber assembly becomes 1 μm or more, and ultrafine fibers cannot be obtained.
　また、本実施の形態において、繊維集合体の溶融粘度は、図４に示すように、４００℃を溶融温度の上限として、１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下であることがより好ましい。その範囲よりも溶融温度が高くなると、たとえ樹脂が酸素と遮断された状況（例えば、窒素雰囲気や密閉状態など）にあるとしても、熱分解が急速に進み、樹脂の重量平均分子量Ｍｗの低下が紡糸段階で起こる。よって、上記同様の理由により、繊維に成りにくく、また、生成された繊維集合体の強度も低下する。 In the present embodiment, the melt viscosity of the fiber assembly is more preferably 100 mPa · s or more and 1000 mPa · s or less, with 400 ° C. being the upper limit of the melting temperature, as shown in FIG. If the melting temperature is higher than that range, the thermal decomposition proceeds rapidly even if the resin is blocked from oxygen (for example, nitrogen atmosphere or sealed state), and the weight average molecular weight Mw of the resin decreases. Occurs at the spinning stage. Therefore, for the same reason as described above, it is difficult to form a fiber, and the strength of the produced fiber assembly is also reduced.
　また、本実施の形態において、繊維集合体の溶融粘度は、図５に示すように、熱可塑性樹脂の融点より１０℃高い温度を溶融温度の下限として、１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下であることがより好ましい。その範囲よりも溶融温度が低くなると、加熱部１１２での樹脂の滞留時間を十分に確保したとしても、樹脂吐出ノズル１０６にて樹脂の溶け残りが生じやすくなるため、紡糸の不安定性を引き起こす。 Further, in the present embodiment, the melt viscosity of the fiber assembly is 100 mPa · s or more and 1000 mPa · s or less, with the temperature lower by 10 ° C. higher than the melting point of the thermoplastic resin as shown in FIG. It is more preferable. If the melting temperature is lower than that range, even if the resin residence time in the heating unit 112 is sufficiently secured, the resin discharge nozzle 106 tends to cause unmelted resin, which causes spinning instability.
　また、本実施の形態において、繊維集合体の溶融粘度は、図６に示すように、１０１１Ｔ－３．６ｍＰａ・ｓ以上１０１２Ｔ－３．６ｍＰａ・ｓ以下の関係式を満たす溶融粘度範囲にあることがより好ましい。なお、図６に示す関係式において、Ｔは、繊維集合体の溶融温度を示し、Ｙは、繊維集合体の溶融粘度を示す（以下、図７および図８において同じ）。この関係式より溶融粘度が低い領域では、極細繊維は生成されるものの、球状粒子も一定量含み、繊維集合体の強度が低下する。この関係式より溶融粘度が高い領域では、極細繊維になりにくい。 In the present embodiment, the melt viscosity of the fiber assembly satisfies the relational expression of 10 11 T −3.6 mPa · s or more and 10 12 T −3.6 mPa · s or less as shown in FIG. More preferably in the melt viscosity range. In the relational expression shown in FIG. 6, T indicates the melting temperature of the fiber assembly, and Y indicates the melt viscosity of the fiber assembly (hereinafter the same in FIGS. 7 and 8). In the region where the melt viscosity is lower than this relational expression, ultrafine fibers are produced, but a certain amount of spherical particles are contained, and the strength of the fiber assembly is lowered. In the region where the melt viscosity is higher than this relational expression, it is difficult to form ultrafine fibers.
　また、本実施の形態において、繊維集合体の溶融粘度は、図７に示すように、２００ｍＰａ・ｓ以上６００ｍＰａ・ｓ以下であり、かつ、２×１０１１Ｔ－３．６ｍＰａ・ｓ以上かつ１０１２Ｔ－３．６ｍＰａ・ｓ以下の関係式を満たす溶融粘度範囲にあることがより好ましい。この関係式より溶融粘度が低い領域では、球状粒子はほぼ含まないものの、繊維長の短い極細繊維が生成されやすく、繊維集合体の重量を増やしても強度が得られにくい。また、この関係式より溶融粘度が高い領域では、繊維径が０．７μｍ以下となり、極細繊維としての特性が向上する。 In the present embodiment, the melt viscosity of the fiber assembly is 200 mPa · s or more and 600 mPa · s or less, and 2 × 10 11 T −3.6 mPa · s or more, as shown in FIG. More preferably, it is in a melt viscosity range satisfying the relational expression of 10 12 T −3.6 mPa · s or less. In the region where the melt viscosity is lower than this relational expression, although spherical particles are not substantially included, ultrafine fibers having a short fiber length are easily generated, and it is difficult to obtain strength even if the weight of the fiber assembly is increased. Further, in the region where the melt viscosity is higher than this relational expression, the fiber diameter is 0.7 μm or less, and the characteristics as an ultrafine fiber are improved.
　また、本実施の形態において、繊維集合体の溶融粘度は、図８に示すように、熱可塑性樹脂の融点より１０℃高くかつ３５０℃以下の温度領域において、２００ｍＰａ・ｓ以上６００ｍＰａ・ｓ以下、かつ、２×１０１１Ｔ－３．６ｍＰａ・ｓ以上かつ１０１２Ｔ－３．６ｍＰａ・ｓ以下の関係式を満たす溶融粘度範囲にあることがより好ましい。この関係式より溶融粘度が低い領域では、球状粒子はほぼ含まないものの、繊維長の短い極細繊維が生成されやすく、繊維集合体の重量を増やしても強度が得られにくい。また、この関係式より溶融粘度が高い領域では、溶融樹脂が酸化劣化している可能性がある。 In the present embodiment, the melt viscosity of the fiber assembly is 200 mPa · s or more and 600 mPa · s or less in a temperature range of 10 ° C. higher than the melting point of the thermoplastic resin and 350 ° C. or less, as shown in FIG. Further, it is more preferable that the viscosity is in a melt viscosity range satisfying a relational expression of 2 × 10 11 T −3.6 mPa · s to 10 12 T −3.6 mPa · s. In the region where the melt viscosity is lower than this relational expression, although spherical particles are not substantially included, ultrafine fibers having a short fiber length are easily generated, and it is difficult to obtain strength even if the weight of the fiber assembly is increased. Further, in the region where the melt viscosity is higher than this relational expression, the molten resin may be oxidized and deteriorated.
　また、本実施の形態において、繊維集合体の密度は、０．０１ｇ／ｃｍ３以上かつ０．０４０ｇ／ｃｍ３以下であることがより好ましい。より高品質な繊維集合体を実現できる。 Further, in this embodiment, the density of the fiber aggregate is more preferably 0.01 g / cm 3 or more and is 0.040 g / cm 3 or less. A higher quality fiber assembly can be realized.
　また、本実施の形態において、繊維集合体の厚さは、１０ｍｍより厚く大きくかつ１００ｍｍよりも薄いことがより好ましい。１μｍ以下の極細繊維からなる繊維集合体は、強度が低いと１０ｍｍを超える厚さを維持することが難しいが、本実施の形態のように繊維強度を高めることにより、繊維集合体の厚さを維持することができる。１μｍ以下の極細繊維からなり、かつ、１０ｍｍを超える厚さを持つ繊維集合体は、吸音材など、幅広い用途への適用が可能となる。なお、繊維集合体は、厚さが１０ｍｍより厚くかつ３０ｍｍよりも薄いことが更に好ましい。 In the present embodiment, the thickness of the fiber assembly is more preferably larger than 10 mm and smaller than 100 mm. A fiber assembly composed of ultrafine fibers of 1 μm or less is difficult to maintain a thickness exceeding 10 mm if the strength is low, but by increasing the fiber strength as in this embodiment, the thickness of the fiber assembly can be reduced. Can be maintained. A fiber assembly made of ultrafine fibers of 1 μm or less and having a thickness exceeding 10 mm can be applied to a wide range of uses such as a sound absorbing material. The fiber assembly is more preferably thicker than 10 mm and thinner than 30 mm.
　以上説明したように、本実施の形態の繊維集合体は、繊維径分布から得られるメジアン径が１μｍ以下の極細繊維でありながら、強度が高いものとなる。例えば、本実施の形態では、繊維一本の直径が５００ｎｍ～１０００ｎｍであり、かつ、１Ｎ以上の強度を有する繊維集合体を得ることができる（後述の実施例参照）。 As described above, the fiber assembly of the present embodiment has high strength while being a very fine fiber having a median diameter of 1 μm or less obtained from the fiber diameter distribution. For example, in the present embodiment, a fiber assembly having a single fiber diameter of 500 nm to 1000 nm and a strength of 1N or more can be obtained (see the examples described later).
　（実施例）
　次に、本開示の実施例について、説明する。なお、本実施例は、上述した本開示の実施の形態を限定するものではない。まず、本実施例について評価する際に用いた項目および評価方法について説明する。 (Example)
Next, examples of the present disclosure will be described. In addition, a present Example does not limit embodiment of this indication mentioned above. First, items and an evaluation method used when evaluating this example will be described.
　（１）溶融紡糸温度
　日本アビオニクス社製　ＴｈｅｒｍｏＧＥＡＲ　Ｇ１２０ＥＸを用いて、紡糸時の溶融樹脂の温度を測定した。 (1) Melt spinning temperature The temperature of the molten resin at the time of spinning was measured using ThermoGEAR G120EX manufactured by Nippon Avionics.
　（２）溶融粘度
　アントンパール社製　回転式粘度計　ＭＣＲ３０２を用いて、繊維集合体の溶融粘度の測定を行った。測定条件として、昇温速度を１０℃／分とし、温度領域を１８０～４００℃とし、せん断速度１０（１／ｓ）をとし、測定環境を窒素雰囲気中とした。この溶融粘度の測定結果を基に、上記（１）の溶融紡糸温度での溶融粘度を算出した。 (2) Melt viscosity Anton Paar's rotational viscometer MCR302 was used to measure the melt viscosity of the fiber assembly. The measurement conditions were a temperature increase rate of 10 ° C./min, a temperature range of 180 to 400 ° C., a shear rate of 10 (1 / s), and a measurement environment in a nitrogen atmosphere. Based on the measurement result of the melt viscosity, the melt viscosity at the melt spinning temperature (1) was calculated.
　（３）繊維径（メジアン径）
　ＰＨＥＮＯＭ－Ｗｏｒｌｄ社製　走査型電子顕微鏡　Ｐｈｅｎｏｍ　Ｇ２　ｐｒｏを用いて、１０，０００倍に拡大した繊維集合体の二次元画像から、繊維２００本をランダムに選出し、繊維直径をそれぞれ計測した。試料には、チャージ防止のために、予めＡｕをスパッタ蒸着した。この繊維径の測定結果を基に、メジアン径を算出した。 (3) Fiber diameter (median diameter)
Using a scanning electron microscope Phenom G2 pro manufactured by PHENOM-World, 200 fibers were randomly selected from a two-dimensional image of a fiber assembly magnified 10,000 times, and the fiber diameters were measured. The sample was pre-sputtered with Au to prevent charging. Based on the measurement result of the fiber diameter, the median diameter was calculated.
　（４）繊維強度
　Ｓｔａｂｌｅ　Ｍｉｃｒｏ　Ｓｙｓｔｅｍｓ社製　テクスチャーアナライザー　ＴＡ．ＸＴ．ｐｌｕｓを用いて、繊維集合体の引張強度を測定した。サンプルサイズは１００×１５ｍｍ、繊維重量（後述する図９において、ｗと表記する）は、０．３ｇ、０．５ｇ、０．７ｇの３種類とした。引張試験では、サンプルの長辺方向を各２０ｍｍ分把持し、下端を固定した状態で上端を長辺方向に１ｍｍ／秒の速度で引き上げ、繊維集合体が切れる際の最大強度を測定し、その測定結果を繊維強度とした。 (4) Fiber Strength Texture Analyzer TA. Manufactured by Stable Micro Systems XT. The tensile strength of the fiber assembly was measured using plus. The sample size was 100 × 15 mm, and the fiber weight (denoted as w in FIG. 9 described later) was three types: 0.3 g, 0.5 g, and 0.7 g. In the tensile test, the long side direction of the sample was gripped by 20 mm each, the upper end was pulled up in the long side direction at a speed of 1 mm / sec with the lower end fixed, and the maximum strength when the fiber assembly was cut was measured. The measurement result was defined as fiber strength.
　（５）重量平均分子量Ｍｗ
　Ｗａｔｅｒｓ製　高温ゲル透過クロマトグラフィー　ＧＰＣ／Ｖ２０００を用いて、重量平均分子量Ｍｗを測定した。測定条件として、溶離液をｏ－ジクロロベンゼンとし、温度を１４５℃とし、試料濃度を１．０ｇ／Ｌとし、流速を１．０ｍＬ／分とした。また、検出器として示差屈折計を用いた。 (5) Weight average molecular weight Mw
The weight average molecular weight Mw was measured using Waters high-temperature gel permeation chromatography GPC / V2000. As measurement conditions, the eluent was o-dichlorobenzene, the temperature was 145 ° C., the sample concentration was 1.0 g / L, and the flow rate was 1.0 mL / min. A differential refractometer was used as a detector.
　（６）融点
　セイコーインスツル製　示差熱量分析装置　ＤＳＣ６２２０を用いて、熱可塑性樹脂の融点を測定した。測定条件として、試料重量を１０ｍｇとし、昇温速度を５℃／分とした。また、窒素雰囲気中にて５０～２２０℃までの温度領域の測定を実施した。ＤＳＣ測定結果から、吸熱反応がピークとなる温度を分析し、融点とした。 (6) Melting point Using a differential calorimeter DSC 6220 manufactured by Seiko Instruments Inc., the melting point of the thermoplastic resin was measured. As measurement conditions, the sample weight was 10 mg, and the temperature elevation rate was 5 ° C./min. In addition, measurement in a temperature range from 50 to 220 ° C. was performed in a nitrogen atmosphere. From the DSC measurement results, the temperature at which the endothermic reaction peaks was analyzed and taken as the melting point.
　次に、本実施例における極細繊維の生成条件のうち、共通の条件について、図１を参照しながら説明する。 Next, common conditions among the production conditions of the ultrafine fibers in this example will be described with reference to FIG.
　材料供給については、定量供給機１０１を用いず、ホッパー１０２内に材料のパウダーまたはペレットを直接投入した。スクリューポンプ１０３として単軸フルフライトスクリューポンプを用い、材料を加熱部１１２まで搬送した。シリンダー１０５は、内径が２０ｍｍ、長さが１００ｍｍであるものを用いた。スクリューポンプ１０３の回転速度は、５ｒｐｍとした。溶融樹脂の加熱部１１２での滞留時間は、概ね１０分程度とした。加熱部１１２にはバンドヒーターを計５個設置し、後述する各実施例の溶融樹脂温度に到達するように設定した。樹脂吐出ノズル１０６の径は、０．５ｍｍとした。高温気流生成装置４０２において圧縮空気を０．３ＭＰａに設定し、トーチヒーターを用いて、後述する各実施例の温度となるように、高速気流を加熱した。エアーノズルの内径は１ｍｍとした。捕集体２００としてロールを用い、繊維集合体を捕集した。ロールの外径は５０ｃｍ、ロールの回転速度は１ｒｐｍとした。ロールの表面には、ポリプロピレン製で、目付２０ｇ／ｍ２の不織布２０１を設置した。 For material supply, powder or pellets of material were directly put into the hopper 102 without using the quantitative feeder 101. A single-axis full flight screw pump was used as the screw pump 103, and the material was conveyed to the heating unit 112. A cylinder 105 having an inner diameter of 20 mm and a length of 100 mm was used. The rotational speed of the screw pump 103 was 5 rpm. The residence time of the molten resin in the heating unit 112 was approximately 10 minutes. A total of five band heaters were installed in the heating unit 112 and set so as to reach the molten resin temperature of each example described later. The diameter of the resin discharge nozzle 106 was 0.5 mm. In the high-temperature airflow generation device 402, the compressed air was set to 0.3 MPa, and the high-speed airflow was heated using a torch heater so as to have the temperature of each example described later. The inner diameter of the air nozzle was 1 mm. A roll was used as the collection body 200 to collect the fiber assembly. The outer diameter of the roll was 50 cm, and the rotation speed of the roll was 1 rpm. A nonwoven fabric 201 made of polypropylene and having a basis weight of 20 g / m 2 was installed on the surface of the roll.
　（実施例１）
　材料として、ポリプロピレンペレット（Ｍｗ＝８７，２００、融点１６８℃、ホモポリマー）を用いた。溶融（紡糸）温度３９０℃、溶融樹脂吐出量３．０ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温４００℃にて紡糸し、不織布上にて繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は２００ｍＰａ・ｓであった。作製された繊維集合体の繊維径は０．７０μｍ、厚み２８ｍｍ、密度０．０１６ｇ／ｃｍ３であり、繊維強度はそれぞれ１．０Ｎ、２．１Ｎ、３．２Ｎと良好であった。 Example 1
Polypropylene pellets (Mw = 87,200, melting point 168 ° C., homopolymer) were used as materials. By extruding the molten resin at a melting (spinning) temperature of 390 ° C. and a molten resin discharge rate of 3.0 g / min, spinning at an air speed of 50 m / sec and an air temperature of 400 ° C., and collecting the fibers on the nonwoven fabric, An assembly was produced. The molten resin viscosity measured at the melting (spinning) temperature was 200 mPa · s. The fiber aggregate produced had a fiber diameter of 0.70 μm, a thickness of 28 mm, a density of 0.016 g / cm 3 , and fiber strengths of 1.0 N, 2.1 N, and 3.2 N, respectively.
　（実施例２）
　材料として、ポリプロピレンワックス（Ｍｗ＝４８，７００、融点１５４℃、ホモポリマー）を用いた。溶融（紡糸）温度２４７℃、溶融樹脂吐出量２．６ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温３００℃にて紡糸し、不織布上に繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は５７１ｍＰａ・ｓであった。作製された繊維集合体の繊維径は０．７１μｍ、厚み２２ｍｍ、密度０．０２１ｇ／ｃｍ３であり、繊維強度はそれぞれ１．０Ｎ、１．６Ｎ、２．３Ｎと良好であった。 (Example 2)
As a material, polypropylene wax (Mw = 48,700, melting point 154 ° C., homopolymer) was used. Fiber assembly is performed by extruding the molten resin at a melting (spinning) temperature of 247 ° C. and a molten resin discharge rate of 2.6 g / min, spinning at a wind speed of 50 m / sec and an air temperature of 300 ° C., and collecting the fibers on the nonwoven fabric. The body was made. The molten resin viscosity measured at the melting (spinning) temperature was 571 mPa · s. The fiber aggregate produced had a fiber diameter of 0.71 μm, a thickness of 22 mm, a density of 0.021 g / cm 3 , and fiber strengths of 1.0 N, 1.6 N, and 2.3 N, respectively.
　（実施例３）
　材料として、ポリプロピレンワックス（Ｍｗ＝３４，６００、融点１５４℃、ホモポリマー）を用いた。溶融（紡糸）温度２０１℃、溶融樹脂吐出量２．６ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温２５０℃にて紡糸し、不織布上に繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は５１４ｍＰａ・ｓであった。作製された繊維集合体の繊維径は０．５８μｍ、厚み１４ｍｍ、密度０．０３４ｇ／ｃｍ３であり、繊維強度はどの繊維重量でも０．７Ｎと弱い値であった。 (Example 3)
As a material, polypropylene wax (Mw = 34,600, melting point 154 ° C., homopolymer) was used. Fiber assembly by extruding the molten resin at a melting (spinning) temperature of 201 ° C. and a molten resin discharge rate of 2.6 g / min, spinning at a wind speed of 50 m / sec and a wind temperature of 250 ° C., and collecting the fibers on the nonwoven fabric. The body was made. The molten resin viscosity measured at the melting (spinning) temperature was 514 mPa · s. The produced fiber assembly had a fiber diameter of 0.58 μm, a thickness of 14 mm, a density of 0.034 g / cm 3 , and a fiber strength as weak as 0.7 N at any fiber weight.
　（比較例１）
　材料として、ポリプロピレンペレット（Ｍｗ＝８７，２００、融点１６８℃、ホモポリマー）を用いた。溶融（紡糸）温度３００℃、溶融樹脂吐出量３．０ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温３００℃にて紡糸し、不織布上に繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は２０００ｍＰａ・ｓであった。作製された繊維集合体の繊維強度はそれぞれ４．５Ｎ、７．０Ｎ、１０．０Ｎと大きい値が得られるものの、得られる繊維径は１．３２μｍと細線化には至らない。なお、この繊維集合体の厚みは１６ｍｍ、密度は０．０２９ｇ／ｃｍ３であった。 (Comparative Example 1)
Polypropylene pellets (Mw = 87,200, melting point 168 ° C., homopolymer) were used as materials. Fiber assembly is performed by extruding the molten resin at a melting (spinning) temperature of 300 ° C. and a molten resin discharge rate of 3.0 g / min, spinning at a wind speed of 50 m / sec and an air temperature of 300 ° C., and collecting the fibers on the nonwoven fabric. The body was made. The molten resin viscosity measured at the melting (spinning) temperature was 2000 mPa · s. Although the fiber strength of the produced fiber assembly can be as large as 4.5 N, 7.0 N, and 10.0 N, respectively, the obtained fiber diameter is 1.32 μm, which does not lead to thinning. The fiber assembly had a thickness of 16 mm and a density of 0.029 g / cm 3 .
　（比較例２）
　材料として、ポリプロピレンワックス（Ｍｗ＝１０，３００、融点１４８℃、ホモポリマー）を用いた。溶融（紡糸）温度２００℃、溶融樹脂吐出量２．６ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温２００℃にて紡糸し、不織布上に繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は、３５ｍＰａ・ｓであった。本比較例では、球状粒子を非常に多く含んだ集合体が形成された。 (Comparative Example 2)
As a material, polypropylene wax (Mw = 10,300, melting point 148 ° C., homopolymer) was used. Fiber assembly is achieved by extruding the molten resin at a melting (spinning) temperature of 200 ° C. and a molten resin discharge rate of 2.6 g / min, spinning at a wind speed of 50 m / sec and an air temperature of 200 ° C., and collecting the fibers on the nonwoven fabric. The body was made. The molten resin viscosity measured at the melting (spinning) temperature was 35 mPa · s. In this comparative example, an aggregate containing a large amount of spherical particles was formed.
　（比較例３）
　材料として、ポリプロピレンワックス（Ｍｗ＝１０，３００、融点１４８℃、ホモポリマー）を用いた。溶融（紡糸）温度１８０℃、溶融樹脂吐出量２．６ｇ／分で溶融樹脂を押し出し、風速５０ｍ／秒、風温２００℃にて紡糸し、不織布上に繊維を捕集することで、繊維集合体を作製した。上記溶融（紡糸）温度で測定した溶融樹脂粘度は、４６ｍＰａ・ｓであった。作製された繊維集合体の繊維強度は、どの繊維重量でも０．２Ｎと非常に小さく、かつ、球状粒子を多く含む繊維集合体となった。繊維径は０．７μｍであった。なお、この繊維集合体の厚みは１０ｍｍ、密度は０．０４４ｇ／ｃｍ３であった。 (Comparative Example 3)
As a material, polypropylene wax (Mw = 10,300, melting point 148 ° C., homopolymer) was used. Fiber assembly is achieved by extruding the molten resin at a melting (spinning) temperature of 180 ° C. and a molten resin discharge rate of 2.6 g / min, spinning at a wind speed of 50 m / sec and an air temperature of 200 ° C., and collecting the fibers on the nonwoven fabric. The body was made. The molten resin viscosity measured at the melting (spinning) temperature was 46 mPa · s. The fiber strength of the produced fiber assembly was as small as 0.2 N at any fiber weight, and a fiber assembly containing many spherical particles was obtained. The fiber diameter was 0.7 μm. The fiber assembly had a thickness of 10 mm and a density of 0.044 g / cm 3 .
　図９は、実施の形態に係る実施例および比較例の繊維集合体２０２の特性を示す図である。図９には、上述した実施例１～３および比較例１～３をまとめて示す。 FIG. 9 is a diagram showing the characteristics of the fiber assembly 202 of the example and the comparative example according to the embodiment. FIG. 9 collectively shows the above-described Examples 1 to 3 and Comparative Examples 1 to 3.
　ここで、図９に示す評価の欄において、「○」は「非常に良い」を意味し、繊維径が１μｍ以下で、かつ、繊維強度が１．０Ｎ以上の繊維集合体が得られた条件を示している。また、「△」は「良い」を意味し、繊維径が１μｍ以下の繊維集合体が得られた条件を示している。また、「×」は「悪い」を意味し、繊維径が１μｍ以上の繊維集合体が得られた条件を示している。 Here, in the evaluation column shown in FIG. 9, “◯” means “very good”, a condition that a fiber aggregate having a fiber diameter of 1 μm or less and a fiber strength of 1.0 N or more was obtained. Is shown. “Δ” means “good”, and indicates the condition under which a fiber assembly having a fiber diameter of 1 μm or less was obtained. Further, “x” means “bad”, and indicates the condition under which a fiber aggregate having a fiber diameter of 1 μm or more was obtained.
　図９に示すように、実施例１～３によれば、比較例１～３と比較して、繊維径が１μｍ以下の極細繊維でありながら、繊維強度が強い繊維集合体が得られることが分かる。さらに、実施例１および２によれば、繊維強度が１．０Ｎ以上の繊維集合体を得ることができ、より好ましい。 As shown in FIG. 9, according to Examples 1 to 3, compared to Comparative Examples 1 to 3, it is possible to obtain a fiber assembly having a high fiber strength while being an ultrafine fiber having a fiber diameter of 1 μm or less. I understand. Furthermore, according to Examples 1 and 2, a fiber aggregate having a fiber strength of 1.0 N or more can be obtained, which is more preferable.
　本開示の繊維集合体は、例えば、吸音材、断熱材、吸着材、フィルターなど、幅広い産業用途に適用できる。 The fiber assembly of the present disclosure can be applied to a wide range of industrial uses such as a sound absorbing material, a heat insulating material, an adsorbing material, and a filter.
　１００　繊維生成装置
　１０１　定量供給機
　１０２　ホッパー
　１０３　スクリューポンプ
　１０４　ヒーター
　１０５　シリンダー
　１０６　樹脂吐出ノズル
　１０７　気流ノズル
　１１１　供給部
　１１２　加熱部
　１１３　延伸部
　１１４　捕集部
　２００　捕集体
　２０１　不織布
　２０２　繊維集合体
　３００　熱可塑性樹脂
　４００　溶融樹脂
　４０１　高温気流
　４０２　高温気流生成装置
　５００　極細繊維 DESCRIPTION OF SYMBOLS 100 Fiber production | generation apparatus 101 Fixed supply machine 102 Hopper 103 Screw pump 104 Heater 105 Cylinder 106 Resin discharge nozzle 107 Airflow nozzle 111 Supply part 112 Heating part 113 Extending part 114 Collection part 200 Collecting body 201 Nonwoven fabric 202 Fiber assembly 300 Thermoplastic resin 400 Molten resin 401 High-temperature air flow 402 High-temperature air flow generation device 500 Ultrafine fiber

Claims (10)

  1. 　熱可塑性樹脂を溶融紡糸することによって得られる繊維集合体であって、
    　前記繊維集合体の繊維径が１μｍ以下のメジアン径を有し、
    　前記繊維集合体の溶融粘度が１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下である、
    　繊維集合体。     A fiber assembly obtained by melt spinning a thermoplastic resin,
    The fiber diameter of the fiber assembly has a median diameter of 1 μm or less,
    The melt viscosity of the fiber assembly is 100 mPa · s or more and 1000 mPa · s or less,
    Fiber assembly.
  2. 　４００℃以下の温度領域において、前記繊維集合体の溶融粘度が、１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下である、
    　請求項１に記載の繊維集合体。     In a temperature region of 400 ° C. or lower, the melt viscosity of the fiber assembly is 100 mPa · s or more and 1000 mPa · s or less.
    The fiber assembly according to claim 1.
  3. 　前記熱可塑性樹脂の融点より１０℃以上高い温度領域において、前記繊維集合体の溶融粘度が、１００ｍＰａ・ｓ以上１０００ｍＰａ・ｓ以下である、
    　請求項１または２に記載の繊維集合体。     In the temperature range higher than the melting point of the thermoplastic resin by 10 ° C. or more, the melt viscosity of the fiber assembly is 100 mPa · s or more and 1000 mPa · s or less.
    The fiber assembly according to claim 1 or 2.
  4. 　Ｔを前記繊維集合体の溶融温度とした場合、
    　前記繊維集合体の溶融粘度が、１０１１Ｔ－３．６ｍＰａ・ｓ以上１０１２Ｔ－３．６ｍＰａ・ｓ以下である、
    　請求項１から３のいずれか１項に記載の繊維集合体。     When T is the melting temperature of the fiber assembly,
    The melt viscosity of the fiber assembly is 10 11 T −3.6 mPa · s or more and 10 12 T −3.6 mPa · s or less.
    The fiber assembly according to any one of claims 1 to 3.
  5. 　Ｔを前記繊維集合体の溶融温度とした場合、
    　前記熱可塑性樹脂の融点より１０℃以上高く４００℃以下である温度領域において、前記繊維集合体の溶融粘度が、２００ｍＰａ・ｓ以上６００ｍＰａ・ｓ以下であり、かつ、２×１０１１Ｔ－３．６ｍＰａ・ｓ以上１０１２Ｔ－３．６ｍＰａ・ｓ以下である、
    　請求項１から４のいずれか１項に記載の繊維集合体。     When T is the melting temperature of the fiber assembly,
    In a temperature range of 10 ° C. to 400 ° C. higher than the melting point of the thermoplastic resin, the fiber aggregate has a melt viscosity of 200 mPa · s to 600 mPa · s and 2 × 10 11 T −3. 6 mPa · s or more and 10 12 T −3.6 mPa · s or less,
    The fiber assembly according to any one of claims 1 to 4.
  6. 　Ｔを前記繊維集合体の溶融温度とした場合、
    　前記熱可塑性樹脂の融点より１０℃以上高く３５０℃以下である温度領域において、前記繊維集合体の溶融粘度が、２００ｍＰａ・ｓ以上６００ｍＰａ・ｓ以下であり、かつ、２×１０１１Ｔ－３．６ｍＰａ・ｓ以上１０１２Ｔ－３．６ｍＰａ・ｓ以下である、
    　請求項１から５のいずれか１項に記載の繊維集合体。     When T is the melting temperature of the fiber assembly,
    In a temperature range of 10 ° C. to 350 ° C. higher than the melting point of the thermoplastic resin, the fiber aggregate has a melt viscosity of 200 mPa · s to 600 mPa · s and 2 × 10 11 T −3. 6 mPa · s or more and 10 12 T −3.6 mPa · s or less,
    The fiber assembly according to any one of claims 1 to 5.
  7. 　前記繊維集合体は、密度が０．０１ｇ／ｃｍ３以上かつ０．０４０ｇ／ｃｍ３以下である、
    　請求項１から６のいずれか１項に記載の繊維集合体。     The fiber aggregate has a density of at most 0.01 g / cm 3 or more and 0.040 g / cm 3,
    The fiber assembly according to any one of claims 1 to 6.
  8. 　前記繊維集合体は、厚さが１０ｍｍより厚くかつ１００ｍｍよりも薄い、
    　請求項１から７のいずれか１項に記載の繊維集合体。     The fiber assembly is thicker than 10 mm and thinner than 100 mm,
    The fiber assembly according to any one of claims 1 to 7.
  9. 　前記繊維集合体は、厚さが１０ｍｍより厚くかつ３０ｍｍよりも薄い、
    　請求項１から７のいずれか１項に記載の繊維集合体。     The fiber assembly is thicker than 10 mm and thinner than 30 mm,
    The fiber assembly according to any one of claims 1 to 7.
  10. 　前記熱可塑性樹脂は、ポリオレフィン系樹脂である、
    　請求項１から９のいずれか１項に記載の繊維集合体。     The thermoplastic resin is a polyolefin resin,
    The fiber assembly according to any one of claims 1 to 9.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6349019B1 (en) * 2017-09-22 2018-06-27 オーウエル株式会社 Melt blown non-woven fabric, its use and production method thereof
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Publication number Priority date Publication date Assignee Title
JP6349019B1 (en) * 2017-09-22 2018-06-27 オーウエル株式会社 Melt blown non-woven fabric, its use and production method thereof
WO2019059360A1 (en) * 2017-09-22 2019-03-28 オーウエル株式会社 Melt-blown nonwoven fabric, use of same, and method for producing same
JP2019056190A (en) * 2017-09-22 2019-04-11 オーウエル株式会社 Melt-blown nonwoven fabric and use thereof and method for producing the same
JP2021534303A (en) * 2018-08-22 2021-12-09 ビーエイエスエフ・ソシエタス・エウロパエアBasf Se Stabilized Rotating Polyolefin
JP7478135B2 (en) 2018-08-22 2024-05-02 ビーエーエスエフ ソシエタス・ヨーロピア Stabilized rotational molded polyolefin

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