Fibers and fiber assemblies

Abstract

This invention provides a fiber containing a poly(3-hydroxyalkanoate) resin, which is capable of improving strength and elongation. The present invention relates to a poly(3-hydroxyalkanoate) fiber, wherein the fiber comprises a poly(3-hydroxyalkanoate) resin and carbon black, wherein the median particle size of the carbon black is 10-500 nm, and the area ratio of carbon black in the cross-section of the fiber is 0.01-10%.

Description

Technical Field

[0001] This invention relates to fibers and fiber assemblies. Background Technology

[0002] In recent years, plastic waste has become a significant burden on the Earth's environment, causing problems such as impacts on ecosystems, the production of harmful gases when burned, and global warming due to the large amount of heat generated during combustion. As a potential solution, the development of biodegradable plastics is gaining popularity.

[0003] In such biodegradable plastics, the carbon dioxide produced when burned, which is derived from plant-based raw materials, is already present in the atmosphere, thus preventing an increase in atmospheric carbon dioxide levels. This is known as carbon neutrality, and it is valued within the framework of the Kyoto Protocol, which sets carbon dioxide emission reduction targets, with the expectation of its active use.

[0004] Recently, from the perspective of biodegradability and carbon neutrality, aliphatic polyester resins, especially poly(3-hydroxyalkanoate) resins, have attracted attention as biodegradable plastics produced by microorganisms using plant-derived raw materials as carbon sources (e.g., Patent Document 1).

[0005] Patent document 2 discloses a multifilament having more than 30 monofilaments, wherein the monofilaments contain a poly(3-polyhydroxyalkanoate) resin and a crystallizing nucleating agent, and the coefficient of variation of the fineness of the monofilaments is less than 33%.

[0006] Such multifilaments, by having a coefficient of variation of the fineness of the monofilaments below 33%, are less likely to contain extremely fine monofilaments. Even with increased draw ratios, the monofilaments are not easily broken, making them easy to stretch at high draw ratios and thus resulting in high-strength multifilaments.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2008 / 018567

[0010] Patent Document 2: International Publication No. 2023 / 022015 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, while it is possible to obtain fibers containing poly(3-hydroxyalkanoate) resins with higher strength, further research on fibers that can achieve improved strength and elongation ratio is insufficient.

[0013] Therefore, the objective of this invention is to provide a fiber containing a poly(3-hydroxyalkanoate) resin that is capable of achieving improved strength and elongation, and to provide a fiber assembly containing the fiber.

[0014] Problem Solving Methods

[0015] After dedicated research, the inventors discovered that by including carbon black with a median particle size within a given range in a fiber containing poly(3-hydroxyalkanoate) resin, and setting the area ratio of carbon black in the fiber cross-section within a given range, the fiber becomes a fiber capable of achieving improved strength and elongation ratio, thus completing the present invention.

[0016] That is, the present invention relates to a poly(3-hydroxyalkanoate) fiber, wherein,

[0017] The aforementioned fibers contain poly(3-hydroxyalkanoate) resins and carbon black.

[0018] The median particle size of the aforementioned carbon black is 10~500 nm.

[0019] In the cross-section of the aforementioned fibers, carbon black occupies an area of ​​0.01 to 10%.

[0020] In addition, the present invention also relates to a fiber assembly comprising the above-mentioned fibers.

[0021] Furthermore, the present invention also relates to a method for manufacturing poly(3-hydroxyalkanoate) fibers, the method comprising:

[0022] Step (A) involves melting a raw material composition comprising a poly(3-hydroxyalkanoate) resin and carbon black to obtain a molten composition;

[0023] Step (B) involves obtaining the molten precursor fiber by discharging the molten composition from the discharge hole.

[0024] Step (C) involves cooling the molten precursor fiber in an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin to obtain unstretched fibers; and

[0025] Step (D) involves stretching the unstretched fibers.

[0026] The median particle size of the aforementioned carbon black is 10~500 nm.

[0027] In 100 vol% of the raw material composition, the raw material composition contains 0.01 to 10 vol% carbon black.

[0028] The stretching ratio in the above process (D) is 250% or more.

[0029] The effects of the invention

[0030] According to the present invention, a poly(3-hydroxyalkanoate) resin fiber can be provided, which is a fiber capable of improving strength and elongation ratio, and a fiber assembly containing the fiber can be provided. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an apparatus for the manufacture of fibers containing poly(3-hydroxyalkanoate) resins.

[0032] Figure 2 This is a schematic diagram of a device used to stretch fibers.

[0033] Symbol Explanation

[0034] A: Raw silk

[0035] B: Fiber

[0036] 1: Raw material feeding hopper

[0037] 2: Extruder

[0038] 3: Gear pump

[0039] 4: Spinning nozzle

[0040] 4a: Discharge port

[0041] 5: Rapid cooling section

[0042] 5a: Box 1

[0043] 6: Box 2

[0044] 8: First traction roller

[0045] 9: Tension Adjustment Roll (Dancer Roll)

[0046] 10: First Winding Machine

[0047] 11: Roll core

[0048] 12: Extraction roller

[0049] 13: Second traction roller

[0050] 14: Third traction roller

[0051] 16: Second Winding Machine Detailed Implementation

[0052] Hereinafter, one embodiment of the present invention will be described.

[0053] The fiber in this embodiment is a poly(3-hydroxyalkanoate) fiber containing poly(3-hydroxyalkanoate) resin and carbon black.

[0054] The median particle size of the carbon black mentioned above is 10~500nm.

[0055] In the cross-section of the aforementioned fibers, carbon black occupies an area of ​​0.01 to 10%.

[0056] (Poly(3-hydroxyalkanoate) resin)

[0057] The fiber in this embodiment comprises the above-described poly(3-hydroxyalkanoate) resin.

[0058] Examples of the aforementioned poly(3-hydroxyalkanoate) resins (hereinafter also referred to as "P3HA") include: poly(3-hydroxyalkanoate) copolymers containing 3-hydroxybutyrate units and other hydroxyalkanoate units, and poly(3-hydroxybutyrate) homopolymers (abbreviated as P3HB).

[0059] Examples of the aforementioned poly(3-hydroxybutyrate) copolymers include, for instance, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviated as P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviated as P3HB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviated as P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate). These can be used alone or in combination of two or more.

[0060] From the viewpoint of further improving the strength and elongation of the fiber, the poly(3-hydroxyalkanoate) resin is preferably the poly(3-hydroxybutyrate) copolymer, and more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0061] When the poly(3-hydroxyalkanoate) resin is the poly(3-hydroxybutyrate) copolymer, from the viewpoint of further improving the strength and elongation of the fiber, it is preferable that the poly(3-hydroxyalkanoate) resin contains 80 mol% or more of 3-hydroxybutyrate units out of 100 mol% of all monomer structural units, more preferably 85.0 mol% to 99.5 mol%, and even more preferably 85.0 mol% to 97.0 mol%.

[0062] It should be noted that the proportion of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin can be determined using the method described in the examples below.

[0063] From the viewpoint of further improving the strength and elongation of the fiber, the weight-average molecular weight of the above-mentioned poly(3-hydroxyalkanoate) resin is preferably 3.0 × 10⁻⁶. 5 ~7.0×10 5More preferably 3.5×10 5 ~7.0×10 5 Further preferred is 4.0×10 5 ~7.0×10 5 The optimal value is 4.5 × 10⁻⁶. 5 ~6.5×10 5 .

[0064] In this embodiment, the weight-average molecular weight refers to the molecular weight determined by gel permeation chromatography (GPC) using chloroform eluent and by converting the molecular weight distribution to polystyrene. As the chromatographic column in this GPC, any suitable column for determining the aforementioned molecular weight can be used.

[0065] For example, the column temperature can be set to 40°C, 3 mg of the target substance can be dissolved in 2 ml of chloroform, and 10 μl can be injected. The flow rate of the chloroform eluent (mobile phase) can be set to 1.0 ml / min, and the weight-average molecular weight (Mw) can be calculated from this. A Shimadzu 20A (manufactured by Shimadzu Corporation) can be used as the GPC device, and a Shodex K-806M (manufactured by Showa Denko) can be used as the column.

[0066] It should be noted that the above-mentioned weight-average molecular weight can be used to determine the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the fiber, or the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin before fiber production.

[0067] The fiber in this embodiment preferably contains more than 50% by weight and less than 100% by weight of poly(3-hydroxyalkanoate) resin, more preferably 80 to 100% by weight, and even more preferably 90 to 100% by weight.

[0068] (Carbon black)

[0069] The fiber in this embodiment contains the aforementioned carbon black. This allows for an increase in the fiber's strength and elongation.

[0070] The median particle size (D50) of the aforementioned carbon black is 10-500 nm, preferably 10-400 nm, and more preferably 10-300 nm. By making the median particle size below 500 nm, fiber breakage is less likely to occur during fiber production (spinning), making fiber production easier. By making the median particle size above 10 nm, carbon black aggregation is suppressed during fiber manufacturing, making the carbon black easier to handle.

[0071] It should be noted that the median particle size can be determined using the method described in the examples below.

[0072] In the cross-section of the aforementioned fiber, the area ratio of carbon black is 0.01 to 10%, preferably 0.05 to 10%, more preferably 0.5 to 10%, and even more preferably 0.5 to 5%. By making the area ratio 0.01% or more, the strength and elongation ratio of the fiber can be improved. By making the area ratio 10% or less, yarn breakage is less likely to occur during spinning, making it easier to produce fibers.

[0073] The above area ratio can be adjusted according to the amount (content) of carbon black added during fiber manufacturing.

[0074] It should be noted that the above area ratios can be obtained using the methods described in the embodiments described later.

[0075] (additive)

[0076] The fibers of this embodiment may contain additives that can be used together with poly(3-hydroxyalkanoate) resin and carbon black, to the extent that they do not impair the effects of the invention.

[0077] Examples of such additives include: nucleating agents, lubricants, plasticizers, spinning oils, stabilizers (antioxidants, UV absorbers, etc.), colorants (dyes, pigments, etc.), inorganic fillers, organic fillers, and antistatic agents.

[0078] To promote the crystallization of poly(3-hydroxyalkanoate) resin, the fibers of this embodiment preferably contain a nucleating agent.

[0079] By including a crystallizing nucleating agent in the fibers of this embodiment, the crystallization of the poly(3-hydroxyalkanoate) resin is promoted during fiber production, making it easier to obtain fibers.

[0080] Examples of nucleating agents for crystallization include sugar alcohols such as pentaerythritol, galactitol, and mannitol; orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, sugar alcohols are preferred, and pentaerythritol is particularly preferred, considering their excellent effect on promoting the crystallization of poly(3-hydroxyalkanoate) resins. These can be used alone or in combination of two or more.

[0081] From the viewpoint that it can further promote the crystallization of poly(3-hydroxyalkanoate) resin and reduce the viscosity of the melt composition described later during fiber production, thereby facilitating fiber production, the content of the nucleating agent in the fiber of this embodiment is preferably 0.05 to 10 parts by weight relative to 100 parts by weight of poly(3-hydroxyalkanoate) resin. This lower limit is more preferably 0.1 parts by weight or more, and even more preferably 0.5 parts by weight or more. Furthermore, this upper limit is preferably 10 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 5 parts by weight or less.

[0082] The fibers in this embodiment may contain a lubricant.

[0083] Examples of such lubricants include compounds having amide bonds.

[0084] Compounds having the above-mentioned amide bonds preferably include those selected from laurylamide, myristamide, stearamide, and styracil. One or more of acid amide and erucamide.

[0085] From the viewpoint that the single fiber exhibits excellent lubricity and that the seepage of the aforementioned lubricant on the fiber surface can be suppressed, the lubricant content in the fiber of this embodiment is preferably 0.05 to 12 parts by weight relative to 100 parts by weight of the aforementioned poly(3-hydroxyalkanoate) resin. This lower limit is more preferably 0.1 parts by weight or more, and even more preferably 0.5 parts by weight or more. Furthermore, this upper limit is more preferably 10 parts by weight or less, even more preferably 8 parts by weight or less, and most preferably 5 parts by weight or less.

[0086] (fiber)

[0087] The fiber in this embodiment may contain one or more monofilaments (hereinafter also referred to as "monofilaments"). That is, the fiber may be a multifilament or a monofilament.

[0088] The aforementioned multifilament has two or more single fibers, preferably more than 12, more preferably 30 to 10,000, more preferably 40 to 5,000, and even more preferably 50 to 3,000.

[0089] The fineness of the single fiber in this embodiment is preferably 1.0 to 15 dtex, more preferably 1.0 to 12 dtex, even more preferably 1.0 to 10 dtex, even more preferably 1.0 to 6.0 dtex, and particularly preferably 1.0 to 5.0 dtex. By having the fineness of the single fiber below 15 dtex, it is advantageous to be able to use the fiber for various applications. By having the fineness of the single fiber above 1.0 dtex, it is easy to manufacture the fiber.

[0090] It should be noted that, when the fiber is a multifilament, the fineness of a single fiber refers to the average fineness of the individual fibers contained in the fiber. When the fiber is a monofilament, the fineness of a single fiber refers to the fineness of the fiber itself. Furthermore, when the fiber is stretched, the fineness can be measured either before or after stretching.

[0091] The fineness of a single fiber can be determined using the method described in the examples described later.

[0092] The strength of the fiber in this embodiment is preferably 2.0 cN / dtex or higher, more preferably 2.5 cN / dtex or higher, and even more preferably 3.0 cN / dtex or higher. Furthermore, the upper limit of the fiber strength in this embodiment is not particularly limited; for example, it can be 8.0 cN / dtex or lower, or 5.0 cN / dtex or lower.

[0093] The strength can be measured using the methods described in the examples below.

[0094] In this embodiment, the maximum elongation ratio of the fiber is preferably 250% or more, more preferably 260% or more, and even more preferably 270% or more. Furthermore, the maximum elongation ratio of the fiber in this embodiment is not particularly limited; for example, it can be 500% or less, or 400% or less.

[0095] The maximum stretch ratio can be determined using the method described in the examples below.

[0096] The fibers in this embodiment can be used as sutures or fibers in fiber assemblies described later.

[0097] (fiber aggregate)

[0098] The fiber assembly of this embodiment includes the aforementioned fibers.

[0099] Examples of such fiber aggregates include: yarn, textiles, woven fabrics, and nonwoven fabrics.

[0100] The aforementioned thread, as a fiber assembly, comprises multiple of the aforementioned fibers, or comprises one or more of the aforementioned fibers and one or more other fibers. Examples of such threads include spun yarns.

[0101] Examples of the aforementioned textiles include: plain weave fabrics, twill weave fabrics, satin weave fabrics, plain weave variation fabrics, twill variation fabrics, satin variation fabrics, variation fabrics, jacquard fabrics, and fabrics with alternating linings and facings. (e.g., double-layered fabrics, multi-layered fabrics, warp-pile fabrics, weft-pile fabrics, gauze fabrics, etc.)

[0102] Examples of the aforementioned woven fabrics (also known as knitted fabrics) include: circular knitting, weft knitting, warp knitting, terry knitting, etc.; examples also include: plain knit fabrics, weft plain knit fabrics (…). ), rib knit fabrics, cotton and wool fabrics (double-knitted fabrics), overlock stitching ( ), double reverse knitting (purl stitch), dembigh stitch, cord stitch, atlas stitch, chain stitch ( ) and lining fabric ( )wait.

[0103] The aforementioned nonwoven fabric can be either long-fiber nonwoven fabric or short-fiber nonwoven fabric.

[0104] From the viewpoint of improving marine biodegradability, the aforementioned fiber aggregate preferably contains 10% by weight or more of the aforementioned fibers, more preferably 20% by weight or more, even more preferably 30% by weight or more, even more preferably 40% by weight or more, even more preferably 50% by weight or more, even more preferably 60% by weight or more, even more preferably 70% by weight or more, even more preferably 80% by weight or more, even more preferably 90% by weight or more, and even more preferably 95% by weight or more. The aforementioned fiber aggregate may contain 100% by weight of the aforementioned fibers.

[0105] The aforementioned fiber aggregate may also include other fibers besides those mentioned above. Other fibers are not particularly limited and can include synthetic fibers, natural fibers, and regenerated fibers. From a biodegradability perspective, other fibers are preferably biodegradable fibers. Examples of biodegradable synthetic fibers include, for example, synthetic fibers containing aliphatic polyesters other than P3HA. Examples of aliphatic polyesters other than P3HA include, for example, polylactic acid, polycaprolactone, polybutylene adipate terephthalate, polybutylene adipate succinate, and polybutylene succinate. Examples of natural fibers include natural cellulose fibers and natural animal fibers. Examples of natural cellulose fibers include, for example, cotton fiber, kapok fiber, flax fiber, industrial hemp fiber, ramie fiber, jute fiber, abaca fiber, and kenaf fiber. Examples of natural animal fibers include, for example, wool fiber, mohair fiber, cashmere fiber, camel hair fiber, alpaca fiber, and angora fiber. Examples of regenerated fibers include: regenerated cellulose fibers such as rayon, mucilage fiber, cuprammonium fiber, and lyocell fiber, as well as regenerated protein fibers such as regenerated collagen fiber.

[0106] The aforementioned fiber aggregates can be used in various fiber products. Examples of fiber products include: clothing, daily necessities, and interior decorations. Examples of clothing include: outerwear, underwear, sweaters, vests, trousers, gloves, socks, scarves, and hats. Examples of daily necessities include: bedding, pillows, cushions, cloth dolls, and hygiene products. Examples of interior decorations include: curtains and carpets.

[0107] (Methods for manufacturing fibers)

[0108] The fiber manufacturing method of this embodiment includes: a step (A) of melting a raw material composition comprising a poly(3-hydroxyalkanoate) resin and carbon black to obtain a molten composition; a step (B) of discharging the molten composition from a discharge hole to obtain a molten precursor fiber; and a step (C) of cooling the molten precursor fiber in an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin to obtain a fiber.

[0109] Next, refer to Figure 1 , 2 The manufacturing method of the above-mentioned fibers will be described.

[0110] In the above-mentioned fiber manufacturing method, firstly, a raw material composition comprising a poly(3-hydroxyalkanoate) resin and carbon black is melted to obtain a molten composition (step (A)). Figure 1 In this method, the raw material composition is fed into the raw material feeding hopper 1, and the raw material composition fed into the raw material feeding hopper 1 is heated and melted using the extruder 2 to obtain a melted raw material composition. When feeding the raw material composition into the raw material feeding hopper 1, materials other than carbon black can be melted to obtain raw material particles, and then these raw material particles and carbon black are fed into the raw material feeding hopper 1. Examples of the extruder 2 include single-screw extruders and twin-screw extruders.

[0111] The melt temperature (hereinafter also referred to as the "extrusion temperature") at which the raw material composition is melted is preferably 135~182°C, more preferably 140~180°C, and even more preferably 140~175°C. By setting the extrusion temperature to 135°C or higher, the poly(3-hydroxyalkanoate) resin is fully melted, increasing the fluidity of the melt and thus facilitating spinning. By setting the extrusion temperature to 182°C or lower, the decrease in the molecular weight of the poly(3-hydroxyalkanoate) resin due to thermal decomposition is less likely to occur, further improving the fiber strength and elongation.

[0112] In the above-described raw material composition, relative to 100 parts by weight of the above-described poly(3-hydroxyalkanoate) resin, the content of the above-described carbon black is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 10 parts by weight, even more preferably 0.5 to 10 parts by weight, and particularly preferably 0.5 to 5 parts by weight. By making this content 0.01 parts by weight or more, the strength and elongation of the fiber can be further improved. By making this content 10 parts by weight or less, yarn breakage is less likely to occur during spinning, and the fiber is easier to produce.

[0113] Next, the molten composition is discharged from the discharge hole to obtain the molten precursor fiber (step (B)). Figure 1 In this method, the above-mentioned molten material is discharged from the discharge hole 4a of the spinning nozzle 4 to obtain the molten precursor fiber A.

[0114] The spinning nozzle 4 described above has one or more discharge holes 4a, preferably more than 12, more preferably 30 to 10,000, more preferably 40 to 5,000, and even more preferably 50 to 3,000.

[0115] The flow rate of the melt discharged from the spinning nozzle 4 is preferably 1.0~20 kg / h, more preferably 2.0~15 kg / h. The flow rate of the melt discharged from the spinning nozzle 4 can be adjusted by the gear pump 3.

[0116] Next, the molten precursor fiber (molten precursor fiber) is cooled in an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin (step (C)). Figure 1 In this method, the molten precursor fiber A is cooled in the first chamber 5a of the quenching section 5 under an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin. This promotes the crystallization of the poly(3-hydroxyalkanoate) resin in precursor fiber A, making precursor fiber A less prone to breakage. It should be noted that the crystallization temperature of the poly(3-hydroxyalkanoate) resin is typically around 50~80°C.

[0117] Furthermore, in the aforementioned cooling process, the molten precursor fiber A is preferably cooled in an atmosphere of 10-35°C, more preferably in an atmosphere of 15-25°C. By setting the temperature of the aforementioned atmosphere to 10°C or higher, it is easier to suppress the fusion adhesion between the precursor fiber and manufacturing equipment such as rollers. In addition, when the fiber is multifilament, it is easier to suppress the fusion adhesion between individual fibers. By setting the temperature of the aforementioned atmosphere to 35°C or lower, the precursor fiber A is less prone to breakage.

[0118] In the above cooling process, the precursor fiber A can be cooled by blowing gas into it. Examples of such gas include air, inert gases (nitrogen, argon, etc.), and water vapor.

[0119] Examples of blowing methods include the circular method and the back-side method. The back-side method involves blowing gas into the precursor fiber A from one direction within the first chamber 5a, viewed from its length direction (a cross-section of the precursor fiber A perpendicular to its length direction). The circular method involves blowing gas into the precursor fiber A through a first chamber 5a having cylindrical sidewalls, and blowing gas in a spiral motion along the inner circumferential surface of the cylindrical sidewalls. It should be noted that the flow direction of the precursor fiber A is approximately parallel to the imaginary axis of the cylindrical sidewalls. The circular method is preferred as the blowing method. The circular method allows for relatively uniform gas blowing onto the precursor fiber A, resulting in more uniform cooling of the precursor fiber A and suppressing deviations in the fineness of the precursor fiber A.

[0120] The preferred gas velocity is 0.01 m / s or higher and less than 0.10 m / s, more preferably 0.01 m / s or higher and less than 0.09 m / s. It should be noted that the gas velocity refers to the gas velocity just before it comes into contact with the precursor fiber A. By keeping the gas velocity below 0.10 m / s, even with increased traction roller speed, the precursor fiber A is less prone to breakage during traction, thus easily improving fiber productivity. By keeping the gas velocity at 0.01 m / s or higher, the molten precursor fiber A can be sufficiently cooled by the gas. As a result, the molten precursor fiber A is less prone to breakage, easily improving fiber productivity.

[0121] Next, in the above-mentioned process (C), the above-mentioned raw filament is pulled by the first traction roller 8 and wound into the core 11 by the first winding machine 10, thereby obtaining the fiber (unstretched fiber).

[0122] The strength of the unstretched fiber is preferably 0.9 cN / dtex or higher, more preferably 1.0 cN / dtex or higher, and even more preferably 1.1 cN / dtex or higher. Furthermore, the upper limit of the fiber strength in this embodiment is not particularly limited, and examples include 5 cN / dtex or lower.

[0123] The fineness of the unstretched fiber is preferably 1.5 to 15 dtex, more preferably 2.0 to 12 dtex, even more preferably 2.5 to 10 dtex, and even more preferably 3.0 to 6.0 dtex.

[0124] The fibers described above can be stretched. That is, the fiber manufacturing method of this embodiment can further include a step (D) of stretching the fibers (unstretched fibers). Figure 2 In this method, the fiber B is pulled from the pull-out roller 12 through the second traction roller 13, stretched between the second traction roller 13 and the third traction roller 14, and wound using the second winding machine 16.

[0125] Alternatively, the speed of the second winding machine 16 can be set lower than the speed of the third traction roller 14 (or a relaxation process can be performed).

[0126] The stretching ratio can be set appropriately, preferably 120% or more (e.g., 120~400%), more preferably 160% or more (e.g., 160~330%), and even more preferably 250% or more (e.g., 250~300%).

[0127] The above stretch ratio can be obtained by the following formula.

[0128] Stretch ratio (%) = Speed ​​of the 3rd traction roller 14 (m / min) / Speed ​​of the 2nd traction roller 13 (m / min) × 100 (%)

[0129] In addition, the final stretch ratio can be set appropriately, preferably 110~380%, more preferably 150~300%.

[0130] The final stretch ratio can be obtained by the following formula.

[0131] Final stretch ratio (%) = Speed ​​of the second winding machine 16 (m / min) / Speed ​​of the second traction roller 13 (m / min) × 100 (%)

[0132] It should be noted that the speed of the second traction roller 13 is the length of the fiber pulled by the second traction roller 13 per unit time. The speed of the third traction roller 14 is the length of the fiber pulled by the third traction roller 14 per unit time. The speed of the second winding machine 16 is the length of the fiber wound by the second winding machine 16 per unit time.

[0133] It should be noted that the present invention is not limited to the embodiments described above. Furthermore, the present invention is not limited by the aforementioned effects. In addition, various modifications can be made to the present invention without departing from its spirit.

[0134] [Public Projects]

[0135] The following items are disclosures of preferred embodiments.

[0136] [Project 1]

[0137] A poly(3-hydroxyalkanoate) fiber, wherein,

[0138] The fiber comprises poly(3-hydroxyalkanoate) resin and carbon black.

[0139] The median particle size of the carbon black is 10~500 nm.

[0140] In the cross-section of the fiber, carbon black occupies an area of ​​0.01 to 10%.

[0141] [Project 2]

[0142] According to the fiber described in Project 1, wherein,

[0143] The poly(3-hydroxyalkanoate) resin is a poly(3-hydroxyalkanoate) copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units.

[0144] [Project 3]

[0145] According to the fiber described in Project 2, wherein,

[0146] The poly(3-hydroxybutyrate) copolymer is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0147] [Project 4]

[0148] The fiber according to any one of items 1 to 3, wherein,

[0149] The fineness of a single fiber is 1.0~15 dtex.

[0150] [Project 5]

[0151] The fiber according to any one of items 1 to 4, wherein,

[0152] The strength of the fiber is above 2.0 cN / dtex.

[0153] [Project 6]

[0154] A fiber assembly comprising the fibers described in any one of items 1 to 5.

[0155] [Project 7]

[0156] According to the fiber assembly described in Project 6, wherein...

[0157] The fiber assembly comprises one or more selected from yarn, textiles, woven fabrics and nonwoven fabrics.

[0158] [Project 8]

[0159] A method for manufacturing poly(3-hydroxyalkanoate) fibers, the method comprising:

[0160] Step (A) involves melting a raw material composition comprising a poly(3-hydroxyalkanoate) resin and carbon black to obtain a molten composition;

[0161] Step (B) involves obtaining the molten precursor fiber by discharging the molten composition through a discharge port;

[0162] Step (C) involves cooling the molten precursor fiber in an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin to obtain unstretched fibers; and

[0163] Step (D) involves stretching the unstretched fibers.

[0164] The median particle size of the carbon black is 10~500 nm.

[0165] In 100 vol% of the raw material composition, the raw material composition contains 0.01 to 10 vol% carbon black.

[0166] The stretching ratio in process (D) is 250% or more.

[0167] Example

[0168] The following describes specific embodiments of the present invention, but these embodiments do not limit the present invention.

[0169] [Measurement and Evaluation Methods]

[0170] (The respective proportions of 3-hydroxybutyrate and 3-hydroxyhexanoate units in P3HB3HH, which is P3HA)

[0171] The proportions of 3-hydroxybutyrate units and 3-hydroxyhexanoate units in P3HB3HH, which is P3HA, are determined as follows.

[0172] First, 2 mL of a mixture of sulfuric acid and methanol (volume of sulfuric acid:volume of methanol = 15:85) and 2 mL of chloroform were added to a 20 mg sample after drying. The sample was then sealed and heated at 100 °C for 140 minutes while keeping it sealed, thus obtaining the first reaction solution containing methyl ester as a decomposition product of P3HA.

[0173] Next, the first reaction solution was cooled, and 1.5g of sodium bicarbonate was slowly added to the cooled first reaction solution for neutralization. The mixture was then allowed to stand until the production of carbon dioxide stopped, thus obtaining the second reaction solution.

[0174] Furthermore, a mixture was obtained by thoroughly mixing the second reaction solution with 4 mL of diisopropyl ether.

[0175] Next, the mixture was centrifuged to obtain the supernatant.

[0176] Next, capillary gas chromatography was used to analyze the monomer unit composition of the above decomposition products in the supernatant under the following conditions, and the content ratio of 3-hydroxybutyrate unit and 3-hydroxyhexanoate (3HH) unit in P3HA was determined.

[0177] Gas chromatograph: Shimadzu GC-17A

[0178] Capillary column: NEUTRA BOND-1 manufactured by GL Science (column length: 25m, column inner diameter: 0.25mm, liquid film thickness: 0.4μm)

[0179] Carrier gas: He

[0180] Column inlet pressure: 100 kPa

[0181] Sample volume: 1 μL

[0182] Regarding temperature conditions, the temperature was increased at a rate of 8°C / minute at 100~200°C, and further increased at a rate of 30°C / minute at 200~290°C.

[0183] (Weight-average molecular weight of P3HA)

[0184] The weight-average molecular weight of P3HA was determined using the method described above.

[0185] (Median particle size of particles (carbon black or silica))

[0186] Using a Partica LA-960V2 manufactured by Horiba Productions, the median particle size of primary particles on a volume basis was determined by laser diffraction / scattering measurements.

[0187] (The area ratio of particles (carbon black or silica) in the cross-section of the fiber)

[0188] The fiber profile was photographed using a Keyence VHX-6000. Based on the area ratio of the carbon black (or silica) portion to the non-carbon black (or silica) portion, the area ratio of carbon black (or silica) in the fiber profile was calculated (hereinafter also referred to as "particle area ratio of the profile").

[0189] (Spinning)

[0190] The situation where the yarn breaks during spinning is rated as "×", and the situation where the yarn does not break but fiber can be obtained is rated as "○".

[0191] (The fineness of a single fiber)

[0192] Using the Search Corporation DC-21 fineness measuring instrument. (DENICON) The fineness of individual fibers was determined.

[0193] It should be noted that, as fineness, the fineness of the unstretched fiber (also known as "unstretched fineness") and the fineness of the fiber stretched to a final stretch ratio of 180% (also known as "fineness at 180% stretch") were measured. Furthermore, as for the fineness of the fiber stretched to a high final stretch ratio (hereinafter also known as "high stretch treatment") (hereinafter also known as "high stretch product fineness"), for Example 1, the fineness of the fiber stretched to a final stretch ratio of 260% was measured; for Example 14, the fineness of the fiber stretched to a final stretch ratio of 240% was measured.

[0194] The fineness is shown in Tables 1 and 2 below.

[0195] (strength)

[0196] For all the monofilaments that make up the fiber, the tensile strength of each monofilament was measured, or more than 10 monofilaments were randomly selected from the fiber and the tensile strength of each monofilament was measured.

[0197] The tensile strength of each monofilament was measured based on JIS L 1015:2021 "Test Method for Short Chemical Fibers" with an initial length of 20 mm and a speed of 20 mm / min.

[0198] Specifically, the load (cN) at break of each monofilament was measured using the Autograph AG-I tensile testing device (manufactured by Shimadzu Corporation) under the following conditions.

[0199] Initial length of each monofilament: 20mm

[0200] Stretching speed: 20mm / min

[0201] Load sensor: A load sensor with a rated capacity of 5N.

[0202] In addition, the fineness of each monofilament is determined using Auto Vibroscop ( The tensile strength of each monofilament was then determined using the following method.

[0203] Tensile strength of each filament (cN / dtex) = Load at break of each filament (cN) / Fineness of each filament

[0204] Next, the arithmetic mean of the tensile strength of each filament is calculated based on its tensile strength, and this value is taken as the strength.

[0205] It should be noted that, as for strength, the strength of the unstretched fiber (also known as "unstretched strength") and the strength of the fiber after being stretched to 180% of its final stretch ratio (also known as "strength at 180% stretch") were measured. Furthermore, as for the strength of the fiber subjected to high stretch treatment (hereinafter also known as "high stretch strength"), for Example 1, the strength of the fiber stretched to 260% of its final stretch ratio was measured; for Example 14, the strength of the fiber stretched to 240% of its final stretch ratio was measured.

[0206] The intensities are shown in Tables 1 and 2 below.

[0207] (Maximum stretch ratio)

[0208] like Figure 2As shown, the unstretched fibers obtained in the embodiment are placed on the pull-out roller 12, pulled by the second traction roller 13 (55m / min, 30°C), stretched between the second traction roller 13 and the third traction roller 14, and heat-treated on the third traction roller 14 heated to 90°C. They are then wound using a second winding machine 16 at a speed of 90% relative to the speed of the third traction roller.

[0209] The speed of the third traction roller 14 is gradually increased from 55 m / min to 1 m / min (the speed of the second winding machine is increased in such a way that it reaches 90% of the speed of the third traction roller). The stretch ratio at the confirmed fiber breaking speed is set as the maximum stretch ratio, which is calculated by the following formula.

[0210] Maximum stretch ratio (%) = Speed ​​of the 3rd traction roller 14 / Speed ​​of the 2nd traction roller 13 × 100

[0211] (Fibers stretched to a final stretch ratio of 180%)

[0212] like Figure 2 As shown, the unstretched fiber obtained in the embodiment is placed on the pull-out roller 12, pulled by the second traction roller 13 (55m / min, 30°C), stretched between the second traction roller 13 and the third traction roller 14 (110m / min, 90°C) (stretch ratio: 200%), heat-treated on the third traction roller 14, and wound by the second winding machine 16 (100m / min), thereby obtaining the fiber stretched with a final stretch ratio of 180%.

[0213] (Fibers stretched to a final stretch ratio of 240%)

[0214] like Figure 2 As shown, the unstretched fiber obtained in the embodiment is placed on the pull-out roller 12, pulled by the second traction roller 13 (55m / min, 30°C), stretched between the second traction roller 13 and the third traction roller 14 (147m / min, 90°C) (stretch ratio: 267%), heat-treated on the third traction roller 14, and wound by the second winding machine 16 (132m / min), thereby obtaining the fiber stretched with a final stretch ratio of 240%.

[0215] (Fibers stretched to a final stretch ratio of 260%)

[0216] like Figure 2As shown, the unstretched fiber obtained in the embodiment is placed on the pull-out roller 12, pulled by the second traction roller 13 (55m / min, 30°C), stretched between the second traction roller 13 and the third traction roller 14 (159m / min, 90°C) (stretch ratio: 289%), heat-treated on the third traction roller 14, and wound by the second winding machine 16 (143m / min) to obtain the fiber stretched with a final stretch ratio of 260%.

[0217] (Method for manufacturing raw material particles)

[0218] First, the following materials are dry-mixed according to the following proportions, and the mixture is then melt-mixed at 150°C using an extruder to obtain raw material granules.

[0219] As a poly(3-hydroxyalkanoate) resin (P3HA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (3-hydroxybutyrate unit content: 94 mol%, 3-hydroxyhexanoate content: 6 mol%, weight average molecular weight (Mw): 582936) (P3HB3HH): 100 parts by weight

[0220] Erucamide (EA): 0.5 parts by weight

[0221] Mountain Acid amide (BA): 0.5 parts by weight

[0222] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neutizer-P): 1.0 parts by weight

[0223] (Example 1)

[0224] The raw material granules prepared by the above method and carbon black (median particle size 100 nm) at a ratio of 1 part by weight to 100 parts by weight of poly(3-hydroxyalkanoate) resin relative to the raw material granules were placed in a plastic bag and manually mixed to obtain a raw material composition. The raw material composition was then heated and melted at an extrusion temperature of 170.0°C using an extruder 2 (single-screw extruder, screw diameter: 40 mm) to obtain a melt. Next, the melt was discharged from 400 discharge holes of the spinning nozzle 4 to obtain precursor yarn A.

[0225] It should be noted that the flow rate of the composition (molten material) discharged from the spinning nozzle is adjusted to 7.0 kg / h using gear pump 3.

[0226] A circulating method was used to spray 20°C gas (air) at a wind speed of 0.08 m / s onto the molten precursor fiber A in the quenching section 5, thereby cooling the precursor fiber A.

[0227] The temperature of the first traction roller 8 is adjusted to 40°C. The cooled raw yarn A is pulled by the first traction roller 8 at a speed of 650 m / min. Then, the raw yarn A is wound onto the bobbin 11, which serves as the core, to obtain a multifilament as an unstretched fiber (number of monofilaments: 400, average fineness of monofilaments: 4.5 dtex).

[0228] (Examples 2-12, Comparative Examples 1-5)

[0229] The median particle size or extrusion temperature of the carbon black particles was changed to the conditions described in Table 1 below, or the amount (content) of carbon black particles was changed to make the particle area ratio of the cross section meet the conditions described in Table 1. Otherwise, the same operation was performed as in Example 1 to try to obtain multifilament as unstretched fiber. Multifilament as unstretched fiber was obtained in Examples 2 to 12 and Comparative Example 1, while in Comparative Examples 2 to 4, the yarn broke during spinning and multifilament was not obtained.

[0230] (Example 13)

[0231] The raw material granules prepared using the above method and 1 part by weight of carbon black (median particle size 100 nm) relative to the raw material granules were placed in a plastic bag and manually mixed. Then, the mixture was heated and melted using an extruder 2 (single-screw extruder, screw diameter: 40 mm) at an extrusion temperature of 170.0 °C to obtain a melt. Next, the melt was discharged from the discharge hole of the spinning nozzle 4 to obtain precursor yarn A.

[0232] It should be noted that the flow rate of the composition (molten material) discharged from the spinning nozzle is adjusted to 7.0 kg / h using gear pump 3.

[0233] A circulating method was used to spray 20°C gas (air) at a wind speed of 0.08 m / s onto the molten precursor fiber A in the quenching section 5, thereby cooling the precursor fiber A.

[0234] The temperature of the first traction roller 8 is adjusted to 40°C. The cooled raw yarn A is pulled by the first traction roller 8 at a speed of 292 m / min. Then, the raw yarn A is wound onto the bobbin 11, which serves as the core, to obtain a multifilament as an unstretched fiber (number of monofilaments: 400, average fineness of monofilaments: 10 dtex).

[0235] (Example 14)

[0236] The raw material granules prepared using the above method and 1 part by weight of carbon black (median particle size 100 nm) relative to the raw material granules were placed in a plastic bag and manually mixed. Then, the mixture was heated and melted using an extruder 2 (single-screw extruder, screw diameter: 40 mm) at an extrusion temperature of 170.0 °C to obtain a melt. Next, the melt was discharged from the discharge hole of the spinning nozzle 4 to obtain precursor yarn A.

[0237] It should be noted that the flow rate of the composition (molten material) discharged from the spinning nozzle is adjusted to 7.0 kg / h using gear pump 3.

[0238] A circulating method was used to spray 20°C gas (air) at a wind speed of 0.08 m / s onto the molten precursor fiber A in the quenching section 5, thereby cooling the precursor fiber A.

[0239] The temperature of the first traction roller 8 is adjusted to 40°C, and the cooled raw yarn A is pulled by the first traction roller 8 at a speed of 1150 m / min. Then, the first winding machine 10 is used to wind the raw yarn A onto the spool that serves as the core 11, thus obtaining a multifilament as an unstretched fiber (number of monofilaments: 400, average fineness of monofilaments: 2.5 dtex).

[0240] (Comparative Example 6)

[0241] Silica (median particle size 100 nm) was used instead of carbon black, and otherwise, as in Example 1, multifilaments as unstretched fibers were obtained.

[0242]

[0243]

[0244] As shown in Table 1, in Examples 1-14 within the scope of this invention, the maximum stretch ratio, unstretched strength, and strength at 180% stretch were all high. In contrast, in Comparative Example 1, which did not contain carbon black, and Comparative Example 5, which contained silica instead of carbon black, the maximum stretch ratio, unstretched strength, and strength at 180% stretch were all low compared to Examples 1-14. Furthermore, in Comparative Examples 2 and 3, which had a large particle area ratio in cross-section, and Comparative Examples 4 and 5, which had a large median particle size of carbon black, yarn breakage occurred during spinning, and multifilaments were not obtained.

[0245] Therefore, according to the present invention, it is possible to provide poly(3-hydroxyalkanoate) resin fibers that are capable of achieving improved strength and elongation.

[0246] It should be noted that, unlike silicon dioxide, carbon black is believed to improve tensile strength and tensile strength due to its excellent affinity with resin.

[0247] In the comparison of examples (Examples 1, 5-8) with only different median particle size, the unstretched strength and the strength at 180% stretch were higher in Examples 1, 5-7 with smaller median particle size than in Example 8 with a median particle size of 500 nm.

[0248] In a comparison of examples (Examples 1-4) with different area proportions of carbon black in the fiber cross-section, Examples 1, 2, and 4, with larger area proportions, showed higher maximum elongation ratios compared to Example 3, which had an area proportion of 0.01%. Furthermore, Examples 1 and 4, with larger area proportions, showed higher maximum elongation ratios, unstretched strength, and strength at 180% stretch compared to Examples 2 and 3, which had an area proportion of less than 0.1%. Additionally, Example 1, with a smaller area proportion, showed a higher maximum elongation ratio compared to Example 4, which had an area proportion of 10%.

[0249] In the comparison of examples with only different fineness (Examples 1, 13, and 14), compared with Example 13, which has an unstretched fineness of 10 dtex and a fineness of 5.6 dtex at 180% stretch, Examples 1 and 14, which have small unstretched fineness and fineness at 180% stretch, have higher maximum stretch ratio, unstretched strength, and strength at 180% stretch.

[0250] In a comparison of examples (Examples 1, 9-12) with only different extrusion temperatures, the maximum stretch ratio was higher in Examples 1, 9-11 with lower extrusion temperatures compared to Example 12 with an extrusion temperature of 180°C.

Claims

1. A poly(3-hydroxyalkanoate) fiber, wherein, The fiber comprises poly(3-hydroxyalkanoate) resin and carbon black. The median particle size of the carbon black is 10~500 nm. In the cross-section of the fiber, carbon black occupies an area of ​​0.01 to 10%.

2. The fiber according to claim 1, wherein, The poly(3-hydroxyalkanoate) resin is a poly(3-hydroxyalkanoate) copolymer containing 3-hydroxybutyrate units and other hydroxyalkanoate units.

3. The fiber according to claim 2, wherein, The poly(3-hydroxybutyrate) copolymer is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

4. The fiber according to any one of claims 1 to 3, wherein, The fineness of a single fiber is 1.0~15 dtex.

5. The fiber according to any one of claims 1 to 3, wherein, The strength of the fiber is above 2.0 cN / dtex.

6. A fiber assembly comprising the fibers according to any one of claims 1 to 3.

7. The fiber assembly according to claim 6, wherein, The fiber assembly comprises one or more selected from yarn, textiles, woven fabrics and nonwoven fabrics.

8. A method for manufacturing a poly(3-hydroxyalkanoate) fiber, the method comprising: Step (A) involves melting a raw material composition comprising a poly(3-hydroxyalkanoate) resin and carbon black to obtain a molten composition; Step (B) involves obtaining the molten precursor fiber by discharging the molten composition through a discharge port; Step (C) involves cooling the molten precursor fiber in an atmosphere below the crystallization temperature of the poly(3-hydroxyalkanoate) resin to obtain unstretched fibers; and Step (D) involves stretching the unstretched fibers. The median particle size of the carbon black is 10~500 nm. In 100 vol% of the raw material composition, the raw material composition contains 0.01 to 10 vol% carbon black. The stretching ratio in process (D) is 250% or more.

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