Crimped yarn of polyhydroxyalkanoate filament and method for producing same

Abstract

The present invention provides: a crimped yarn of polyhydroxyalkanoate filament, which has excellent texture when used for a fabric; and a method for producing the same. The present invention relates to: a crimped yarn of polyhydroxyalkanoate filament in which the number of crimps per 1 m is 300 crimps / m to 4,000 crimps / m inclusive; and a method for producing a crimped yarn of polyhydroxyalkanoate filament in which the number of crimps per 1 m is 300 crimps / m to 4,000 crimps / m inclusive, the method including a step for false twisting a polyhydroxyalkanoate filament. The step for false twisting includes: a step for heating the polyhydroxyalkanoate filament at a temperature of 50°C to 150°C inclusive in a twisted state; a step for untwisting; and a step for winding the crimped yarn.

Description

Polyhydroxyalkanate long fiber crimped yarn, and method for producing the same

[0001] The present invention relates to a polyhydroxyalkaneate long fiber crimped yarn and a method for producing the same.

[0002] In recent years, environmental problems caused by plastic waste have come into sharp focus, and the realization of a circular economy on a global scale is eagerly awaited. One of these problems is the release of microplastics into the environment, and among these, microplastics released into the ocean are considered a major issue because they not only destroy marine ecosystems when ingested by marine organisms, but also spread pollution as humans and wildlife ingest them. Furthermore, recent research has highlighted that approximately 30% of microplastics are derived from synthetic fibers, and a solution is needed from the entire textile industry.

[0003] The textile products mentioned above include types such as long fibers, short fibers, woven fabrics, knitted fabrics, and nonwoven fabrics. Among these, woven fabrics are widely used in clothing products such as shirts, bedding materials such as sheets, bed pads, and pillowcases, and automotive interior materials. Furthermore, there is a high possibility that microfibers will be released into the ocean via the air, soil, rivers, and wastewater during use and disposal, making it desirable to replace them with materials that decompose in the ocean.

[0004] To address the above issues, studies have been conducted to replace synthetic fibers such as polyester, acrylic, and nylon, which do not decompose in the ocean, with polysaccharides such as cellulose, which do decompose in the ocean, such as cotton, bamboo, and kenaf. However, complete replacement is not possible because the single-fiber strength is lower than that of synthetic fibers, and it is difficult to create fibers with the unique functions of synthetic fibers, such as moisture content, hygroscopicity, and moisture release.

[0005] In contrast, polyhydroxyalkanetes (hereinafter sometimes abbreviated as "PHA"), which are bio-derived polymers, are currently attracting attention from the perspective of reducing and fixing carbon dioxide emissions (carbon neutrality). Because PHAs have high biodegradability, in particular, they are marine biodegradable, meaning they decompose in the ocean. Therefore, their use is being considered for various molded products such as fibers that detach from products and flow into the ocean, and films that are dumped into the ocean.

[0006] Patent Document 1 below describes a multifilament for stretching PHA and a method for manufacturing the same, a multifilament and a method for manufacturing the same, and a staple and a method for manufacturing the same.

[0007] International Publication No. 2023 / 022015

[0008] Polyhydroxyalkaneses (PHAs) have high biodegradability in marine environments, but their melting and softening temperatures are lower than other synthetic resins, and their glass transition temperature is below room temperature, making them susceptible to degradation due to secondary crystallization. Therefore, when used in fibers, not only is spinning difficult, but post-processing after spinning is also challenging, and it is difficult to obtain processed yarn simply by applying general polyester processing methods.

[0009] Furthermore, while Patent Document 1 describes a crimped short fiber and a method for manufacturing it, it does not disclose the crimping process for long fibers, and therefore, crimped long fiber yarn cannot be obtained through a similar process.

[0010] In view of the above-mentioned problems, the problem that the present invention aims to solve is to provide a polyhydroxyalkaneate long fiber crimped yarn that has excellent texture when used in woven fabrics, and a method for producing the same.

[0011] The inventors of this invention diligently studied and conducted numerous experiments to solve the aforementioned problem, and as a result, unexpectedly discovered that the problem could be solved by the following configuration, thus completing the present invention.

[0012] In other words, the present invention is as follows: [1] A polyhydroxyalkanat filament crimped yarn having a crimp count of 300 or more per meter and 4000 or less per meter. [2] The polyhydroxyalkanat filament crimped yarn according to [1], wherein the degree of crystal orientation of the α structure of the polyhydroxyalkanat is 65% or more. [3] The polyhydroxyalkanat filament crimped yarn according to [2], wherein the degree of crystal orientation of the α structure of the polyhydroxyalkanat is 75% or more. [4] The polyhydroxyalkanat filament crimped yarn according to any one of [1] to [3], wherein the crimp count of 510 or more per meter. [5] The polyhydroxyalkanat filament crimped yarn according to any one of [1] to [4], which is a false-twisted yarn. [6] The polyhydroxyalkanete long fiber crimped yarn according to any one of [1] to [5], wherein the degree of crystallinity of the polyhydroxyalkanete is 40% or more. [7] The polyhydroxyalkanete long fiber crimped yarn according to any one of [1] to [6], wherein the X-ray diffraction intensity ratio Iβ / Iα of the β structure and α structure of the polyhydroxyalkanete is 0.6 or less. [8] The polyhydroxyalkanete long fiber crimped yarn according to any one of [1] to [7], wherein the polyhydroxyalkanete is a homopolymer of 3-hydroxybutyrate, or a copolymer consisting of a first monomer unit of 3-hydroxybutyrate and a second monomer unit. [9] The polyhydroxyalkanete long fiber crimped yarn according to [8], wherein the copolymerization ratio of the second monomer unit is 15 mol% or less.

[10] A polyhydroxyalkanate long fiber crimped yarn according to any one of [1] to [9], wherein the single filament fineness is 15 denier or less.

[11] A polyhydroxyalkanate long fiber crimped yarn according to any one of [1] to

[10] , wherein the long fiber crimped yarn is a multifilament, and the number of single filaments constituting the multifilament is 10 or more.

[12] A polyhydroxyalkanate long fiber crimped yarn according to any one of [1] to

[11] , wherein the oil content is 0.3% or more and 10% or less.

[13] A method for producing a crimped polyhydroxyalkanate filament yarn, comprising the steps of false-twisting a polyhydroxyalkanate filament; wherein the false-twisting step includes the steps of heating the twisted filament at 50°C to 150°C, untwisting the filament, and winding up the yarn after crimping, the number of crimps per meter being 300 or more and 4000 or less.

[14] The method for producing the polyhydroxyalkanate filament yarn according to

[13] , wherein the polyhydroxyalkanate filament used in the false-twisting step has a crystallinity of 40% or more and a crystal orientation of the α structure of 65% or more.

[15] The method for producing the polyhydroxyalkanate filament yarn according to

[13] or

[14] , wherein the false-twisting step is carried out using a pin-type, friction-type, or belt-type false-twisting device.

[16] The manufacturing method according to any one of

[13] to

[15] , wherein the heating time at the heat source in the step of heating the twisted yarn at 50°C to 150°C is 5 seconds or less.

[17] The manufacturing method according to any one of

[13] to

[16] , wherein the stretch ratio in the step of heating the twisted yarn is 80% or less of the elongation of the yarn before false twisting.

[18] The manufacturing method according to

[17] , wherein the stretch ratio is 68% or less.

[19] The manufacturing method according to any one of

[13] to

[18] , wherein the false twisting process includes a tension fluctuation suppression step before the twisting section.

[20] The manufacturing method according to any one of

[13] to

[19] , wherein the false twisting process includes a step of applying an oil before the twisting section.

[21] The manufacturing method according to any one of

[13] to

[20] , which includes a step of heating the untwisted yarn at 50°C to 150°C.

[22] The manufacturing method according to

[21] , wherein the tension in the step of heating the untwisted material at 50°C to 150°C is 10 cN or less.

[23] The manufacturing method according to any one of

[13] to

[22] , wherein the tension in the winding step is 10 cN or less.

[0013] The polyhydroxyalkanate long-fiber crimped yarn of the present invention exhibits excellent texture when used in woven fabrics.

[0014] The embodiments of the present invention will now be described in detail. One embodiment of the present invention is a polyhydroxyalkanate long fiber crimped yarn having a crimp count of 300 or more and 4000 or less per meter. The lower limit of the crimp count per meter is 300 or more, preferably 510 or more, more preferably 600 or more, and most preferably 700 or more. A crimp count of 300 or more enhances the texture when the yarn is woven into a fabric. The upper limit of the crimp count is 4000 or less, preferably 3500 or less, more preferably 2500 or less, and most preferably 2000 or less. If the crimp count is 4000 or less, single thread breakage and yarn breakage during the crimping process can be reduced, fluffing after the crimping process is less likely to occur, and the texture after the yarn is woven into a fabric can be improved. In this specification, the "number of crimps" can be measured according to the method defined in JIS L 1015. A 25 mm dividing line is created on a smooth, glossy piece of paper. One single filament is drawn from each of 30 random locations on the fiber sample. Each drawn single filament is then glued to both ends, leaving a slack of 25 ± 5% relative to the dividing line. Each of these single filaments is attached to the grips of a crimp tester (Intec SE-9N). After cutting the paper piece, the distance between the grips (divided distance) (mm) when the initial load is applied to the sample is read, and the average number of crimps per 25 mm section is calculated. The initial load was set to 0.18 mN × single filament fineness (dtex) / 100, and the number of crimps was calculated by counting all the peaks and valleys and dividing by 2. The crimp count (creps / m) was calculated by multiplying this average value by 40.

[0015] The form of the polyhydroxyalkanate long-fiber crimped yarn can be false-twisted yarn, machine-embossed yarn, or blast-embossed yarn, but false-twisted yarn is preferred from the viewpoint of texture and productivity. False-twisted yarn has a structure in which regular helical crimps are imparted to the long fibers, resulting in high elasticity and bulkiness. Therefore, it can be processed into a fabric with a good texture. On the other hand, machine-embossed yarn with a zigzag two-dimensional crimp structure and blast-embossed yarn with a three-dimensional random crimp structure have excellent bulkiness, but the crimps are irregular and the elasticity is less than that of false-twisted yarn.

[0016] By using polyhydroxyalkanate to produce long-fiber crimped yarn, it is possible to perform crimping processes such as false twisting, unlike natural fibers, while maintaining marine biodegradability. There are no restrictions on the type of polyhydroxyalkanate that constitutes the polyhydroxyalkanate long-fiber crimped yarn of this embodiment, but it is preferably a polyhydroxyalkanate containing 3-hydroxybutyrate as a monomer unit, and more preferably P3HB, which is a homopolymer of 3-hydroxybutyrate, or a copolymer consisting of 3-hydroxybutyrate as the first monomer unit and a second monomer unit. Among the copolymers, P3HB4HB, PHBV, and PHBH are preferred, and P3HB4HB and PHBV are more preferred. Furthermore, if PHB is a homopolymer of 3-hydroxybutyrate, its high mechanical strength can reduce single-fiber breakage and yarn breakage during crimping. If it is a copolymer consisting of a first monomer unit of 3-hydroxybutyrate and a second monomer unit, it can maintain the mechanical strength derived from the first monomer unit while reducing single-fiber breakage and yarn breakage during crimping due to the flexibility provided by the second monomer unit, and is less prone to fuzzing after crimping.

[0017] In this specification, the term "P3HB" means [-O-CH(CH ３ ) - CH ２An aliphatic polyester composed only of monomer units of 3-hydroxybutyrate represented by [-CO-], and the term "P3HB4HB" has a monomer unit of 3-hydroxybutyrate as the first monomer unit, and as the second monomer unit, [-O-CH ２ -CH ２ -CH ２ -CO-] is an aliphatic polyester containing 4-hydroxybutyrate, and the term "PHBV" has a monomer unit of 3-hydroxybutyrate as the first monomer unit, and as the second monomer unit, [-O-CH(C ２ H ５ )-CH ２ -CO-] is an aliphatic polyester containing 3-hydroxyvalerate, and the term "PHBH" has a monomer unit of 3-hydroxybutyrate as the first monomer unit, and as the second monomer unit, [-O-CH(C ３ H ７ )-CH ２ -CO-] is an aliphatic polyester containing 3-hydroxyhexanoate.

[0018] When the polyhydroxyalkanoate of the present embodiment is a copolymer composed of 3-hydroxybutyrate and a second component, the ratio of the second monomer unit to all monomer units (hereinafter abbreviated as the copolymerization ratio) is preferably 15 mol% or less, more preferably 9 mol% or less, and still more preferably 6 mol% or less. When the copolymerization ratio is 15 mol% or less, sufficient mechanical properties are exhibited even after the yarn is crimped, and it is less likely to cause single yarn breakage or yarn breakage during post-processing steps such as fabric formation and dyeing. In addition, by increasing the flexibility of the fiber, single yarn breakage and yarn breakage during the crimping process are less likely to occur, and fluff after the crimping process is less likely to occur. From the viewpoint of excellent post-processing properties, the lower limit of the copolymerization ratio is preferably 1 mol% or more.

[0019] In this specification, the "copolymerization ratio" can be measured by the following method. An aliphatic copolymer polyester is dissolved in deuterated chloroform (chloroform-d, 99.8%, manufactured by Fujifilm Wako Pure Chemical Industries) to a concentration of 1.5% by mass to prepare the measurement sample. A nuclear magnetic resonance spectrometer (Bruker BioSpin AVANCE II 400) is used, with an observation frequency of 400 MHz, 64 integration cycles, a chemical shift reference of 7.26 ppm chloroform (chloroform manufactured by Fujifilm Wako Pure Chemical Industries), and deuterated chloroform as the locking solvent, and 1H-NMR measurement is performed. When 4-hydroxybutyrate is included as the second monomer unit, the integral value of the triplet peak observed at a chemical shift of 4.1 ppm ± 0.2 is taken as A, and the integral value of the quartet peak observed at a chemical shift of 5.3 ± 0.2 ppm is taken as B. The copolymerization ratio C (mol%) is calculated using the following formula: C = (A / 2) / (A / 2 + B) × 100 (mol%). When 3-hydroxyvaliate is included as the second monomer unit, D is the integral value of the triplet peak observed at a chemical shift of 0.88 ± 0.2 ppm, and E is the integral value of the doublet peak observed at a chemical shift of 1.25 ppm ± 0.2 ppm. The copolymerization ratio F (mol%) is calculated using the following formula: F = (D / 3) / (D / 3 + E / 3) × 100 (mol%). When 3-hydroxyhexanoate is included as the second monomer unit, G is the integral value of the triplet peak observed at a chemical shift of 0.90 ± 0.2 ppm, and H is the integral value of the doublet peak observed at a chemical shift of 1.30 ppm ± 0.2 ppm. The copolymerization ratio I (mol%) is calculated using the following formula: I = (G / 3) / (G / 3 + H / 3) × 100 (mol%). Methods for controlling the copolymerization ratio include appropriately selecting microorganisms, adjusting the composition conditions of the fermentation raw materials and culture conditions, but the control method is not particularly limited.

[0020] Unlike other resins, PHA has a glass transition temperature below room temperature, which means it has weak crimp structure retention at room temperature. To enable the maintenance of the crimp structure even in post-processing and actual usage environments, it is necessary to adjust the crystallinity of the polyhydroxyalkanete constituting the polyhydroxyalkanete long-fiber crimped yarn of this embodiment. Preferably, the crystallinity of the polyhydroxyalkanete constituting the polyhydroxyalkanete long-fiber crimped yarn of this embodiment is 40% or more, more preferably 45% or more, even more preferably 50% or more, and most preferably 60% or more. If the crystallinity is 40% or more, it will have sufficient mechanical properties, and the yield strength of the yarn, i.e., the maximum strength that can be reversibly changed, will be higher, and the crimp structure retention will be improved. Specifically, the number of crimps will not change easily after false twisting, and as a result, there will be little change in the texture of the resulting fabric. There is no specific upper limit to the degree of crystallinity, but it is preferably 90% or less, more preferably 80%, and most preferably 70% or less. If the degree of crystallinity is 90% or less, single-fiber breakage and thread breakage due to tension during processing are suppressed. In this specification, "degree of crystallinity" can be measured by the following method. The degree of crystallinity is measured using a differential scanning calorimeter (Perkin Elmer, DSC8500) equipped with an intracooler. The measurement atmosphere is nitrogen (50 ml / min), and the temperature is raised from -50°C to 200°C at a rate of 10°C / min, and the sample is held for 1 minute to completely melt it. The melting point peak appearing in the measured DSC curve (thermogram) is integrated to calculate the melting energy. If the melting energy is J (J / g), the degree of crystallinity K (%) is calculated by the following formula. The sample should be approximately 1 mg, and an aluminum sample pan (Hitachi High-Tech Al autosampler sample container, Φ6.8 H2.5 mm) should be used. Indium should be used for temperature calibration. K = J / (146 × (100 - copolymerization ratio of the sample) / 100) × 100 (%)

[0021] PHA has a problem in that, due to the high stereoregularity of its constituent units, the molecular chains tend to align regularly and spherulite, resulting in low strength. Therefore, in order to maintain sufficient strength and crimped structure even in post-processing and actual usage environments, it is necessary to adjust the degree of crystal orientation of the α structure of the polyhydroxyalkanete constituting the polyhydroxyalkanete long fiber crimped yarn of this embodiment. The degree of crystal orientation of the α structure of the polyhydroxyalkanete constituting the polyhydroxyalkanete long fiber crimped yarn of this embodiment is preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, particularly preferably 80% or more, and most preferably 90% or more. The α structure referred to here is a lamellar crystal structure consisting of helical folding, and is a higher-order structure that greatly contributes to the mechanical strength of the molded article. If the degree of crystal orientation of the α structure is 65% or more, sufficient mechanical properties, especially strength, will be exhibited. Furthermore, the increased single-fiber strength makes it less likely for single-fiber breakage or yarn breakage to occur due to the relaxation of the crystal structure by heat during post-processing steps such as fabrication and dyeing. In addition, the yield point elongation is increased, meaning that the maximum reversible elongation is increased, and the ability to maintain the crimp structure is improved. Specifically, the number of crimps does not change easily after false-twist processing, resulting in less change in the texture of the resulting fabric. There is no particular upper limit, but a realistic degree of orientation is 99% or less.

[0022] The degree of α-crystal orientation in a crimped polyhydroxyalkaneate filament yarn depends on the degree of α-crystal orientation of the yarn before crimping. To adjust the degree of α-crystal orientation of the yarn before crimping, it is important to perform cold drawing and spinning at a high draw ratio, and the higher the draw ratio, the higher the degree of orientation. The temperature during cold drawing should be 30°C or lower. The cold drawing ratio is preferably 4 times or more, more preferably 7 times or more, and even more preferably 10 times or more. If the cold drawing ratio is 4 times or more, the degree of α-crystal orientation will be 65% or more.

[0023] In this specification, the "degree of crystal orientation of the α structure" can be measured by the following method. Using an X-ray structure evaluation device (Rigaku, SmartLab) and a multidimensional pixel array detector (Rigaku, HiPix-3000), the X-ray source is Cu, the collimator diameter is 0.1 mm, the X-ray wavelength is 0.1 nm, the camera length is 27 mm, and the exposure time is 30 min. The test specimen is placed perpendicular to the X-ray beam and parallel to the detector to obtain a two-dimensional diffraction image. In the WAXD measurement, the diffraction angle range from 2θ = 15° to 18° in the WAXD image is separated as (020) plane diffraction peaks. The region containing the (020) plane diffraction peaks is selected in a ring shape, and all diffraction intensities with the same azimuthal angle are integrated. By plotting these intensities against the azimuthal angle, a one-dimensional azimuthal profile is created. The full width at half maximum (FWHM) of the peak at the location of the diffraction point is measured. The degree of orientation (%) is calculated using the following formula: Degree of orientation (%) = (180 - FWHM) / 180 × 100 (%).

[0024] The X-ray diffraction intensity ratio Iβ / Iα of the β structure and α structure of the polyhydroxyalkanete long fiber crimped yarn in this embodiment is preferably 0.6 or less, more preferably 0.55 or less, and even more preferably 0.25 or less. The β structure referred to here is a β-type crystal structure formed by elongated chains, which has low thermodynamic stability. If the X-ray diffraction intensity ratio Iβ / Iα of the β structure and α structure is 0.6 or less, the unstable β structure is less likely to disappear over time, resulting in less change in form after crimping and excellent structural retention of the crimp. For example, the number of crimps does not change easily after false twisting, resulting in less change in the texture of the resulting fabric.

[0025] In this specification, the "X-ray diffraction intensity ratio of β-structure to α-structure Iβ / Iα" can be measured by the following method. Using an X-ray structure evaluation device (Rigaku, SmartLab) and a multidimensional pixel array detector (Rigaku, HiPix-3000), the X-ray source is Cu, the collimator diameter is 0.1 mm, the X-ray wavelength is 0.1 nm, the camera length is 27 mm, and the exposure time is 30 min. The test specimen is placed perpendicular to the X-ray beam and parallel to the detector to obtain a two-dimensional diffraction pattern. When the diffraction intensity distribution in the equatorial direction of the two-dimensional diffraction pattern is measured, the diffraction intensity is composed of scattering by amorphous materials and diffraction by crystals. Diffraction by crystals includes diffraction of α-structures and β-structures, each producing diffraction at specific positions, and the diffraction intensity is proportional to the amount of crystals. Therefore, by taking the ratio of the diffraction intensity based on the α-structure to the diffraction intensity based on the β-structure, an index regarding the amount of β-structure can be obtained. However, because the intensity based on amorphous scattering interferes, it is necessary to remove the influence of the intensity based on amorphous scattering in order to determine the amount of β structure in the crystal. Since the intensity based on amorphous scattering is observed as a broader baseline elevation than the intensity based on crystal diffraction, the line connecting 2θ = 15° and 21°, where the influence of diffraction from the crystal is small, is considered to be the intensity based on amorphous scattering, and this amount is subtracted from the diffraction intensity. In the subsequent diffraction intensity distribution, the maximum value between diffraction angles 2θ = 15° and 18° is taken as the diffraction intensity from the α structure (Iα), and the maximum value between diffraction angles 18° and 21° is taken as the diffraction intensity from the β structure (Iβ). The ratio of the two, Iβ / Iα, is taken as the X-ray diffraction intensity ratio of the β structure to the α structure.

[0026] The weight-average molecular weight of the polyhydroxyalkaneate constituting the polyhydroxyalkaneate long-fiber crimped yarn of this embodiment is preferably 150,000 or more, more preferably 200,000 or more, and even more preferably 250,000 or more. If the weight-average molecular weight is 150,000 or more, sufficient mechanical properties, especially strength, are exhibited even after crimping. Furthermore, the upper limit of the weight-average molecular weight is preferably 3,000,000 or less, from the viewpoint of enabling practically stable post-processing such as dyeing and fabrication.

[0027] The weight-average molecular weight / number-average molecular weight of the polyhydroxyalkanete constituting the polyhydroxyalkanete long-fiber crimped yarn of this embodiment is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less. If the weight-average molecular weight / number-average molecular weight is 10 or less, post-processing such as dyeing and fabrication is stable, and the mechanical properties are stable. From the viewpoint of practical synthesis feasibility, the lower limit of the weight-average molecular weight / number-average molecular weight is 1.1 or more.

[0028] In this specification, "weight-average molecular weight" and "number-average molecular weight" can be measured by the following method. Dissolve the sample in chloroform (chloroform manufactured by Fujifilm Wako Pure Chemical Industries) at a concentration of 0.1% by mass. Use a gel permeation chromatography apparatus (Tosoh HLC-8320GPC) and a guard column (Tosoh TSKgel guardcolumn SuperHZ-L) or an analytical column (Tosoh TSKgel SuperHZM-M). Set the column temperature to 40°C, the eluent to chloroform, the flow rate to 0.35 mL / min, the injection volume to 20 μL, and the detector to RI. Measure a polystyrene standard (Agilent Technologies EasiCal PS-1) and create a calibration curve using data processing software (Tosoh HLC-8320GPC Ecosec-WS). Samples of aliphatic copolymer polyester molded articles are similarly measured, and the weight-average molecular weight and number-average molecular weight are calculated from the calibration curve.

[0029] The method for synthesizing the polyhydroxyalkanet that constitutes the polyhydroxyalkanet long-fiber crimped yarn of this embodiment is not particularly limited, but it is preferable that it be produced from microorganisms. As an example of a microorganism that produces aliphatic copolymer polyesters, a microorganism capable of producing PHAs can be mentioned. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other natural microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus are also known, and in these microorganisms, PHAs accumulate within the bacterial cells. Furthermore, genetically modified microorganisms into which various PHA synthesis-related genes have been introduced may be used, or the culture conditions, including the type of substrate, may be optimized.

[0030] The polyhydroxyalkaneate long-fiber crimped yarn of this embodiment is not particularly limited as long fibers such as monofilament yarn or multifilament yarn, but is preferably multifilament. If multifilament crimped yarn is used, the single-fiber fineness becomes smaller, which increases the bulkiness after processing and further improves the texture when processed into fabric.

[0031] The upper limit of the number of fibers constituting the multifilament in this embodiment is preferably 300 filaments or less, more preferably 250 filaments or less, even more preferably 200 filaments or less, and most preferably 150 filaments or less. If the number of fibers is 300 filaments or less, it is possible to improve the bulkiness of the fibers while suppressing fiber breakage during crimping and use, and fluffing after processing, which can occur due to the single filament fineness becoming too low. The lower limit of the number of fibers can be appropriately adjusted depending on the total fineness of the fibers for the intended application, but is preferably 10 filaments or more, more preferably 15 filaments or more, and even more preferably 20 filaments or more. By increasing the number of fibers to 10 filaments or more, it is possible to increase the bulkiness after crimping compared to monofilament. The "number of single filament fibers constituting the multifilament" in this specification can be measured by the following method. The cross-section of the fiber was observed using an electron microscope JSM-6510 manufactured by JEOL Ltd., and the number of single filaments was measured as the number of single filament fibers constituting the multifilament.

[0032] The total fineness of the long-fiber crimped yarn containing polyhydroxyalkanete in this embodiment is preferably 10D or more and 300D or less, and more preferably 10D or more and 200D or less. By setting the total fineness to 10D or more, practically usable mechanical properties are achieved, and single-fiber breakage, yarn breakage, and abrasion during fabrication can be suppressed. If the total fineness exceeds 300D, the yarn becomes hard, and the texture of the fabric deteriorates. In this specification, the term "total fineness" can be measured by the following method. The long fibers are conditioned overnight in an atmosphere of room temperature 23°C and humidity 50% RH. Ten 1m sections of the conditioned sample are cut out under a load that fully unfolds the crimp but does not stretch the yarn, and the weight of each section is measured. The number average value is multiplied by 10000 to obtain the total fineness (dtex) of the sample. When converting the total fineness to denier, the total fineness (dtex) was multiplied by 0.9 to obtain the total fineness (D).

[0033] The fineness of the single filaments constituting the polyhydroxyalkaneate long-fiber crimped yarn of this embodiment is preferably 15D or less, more preferably 10D or less, and even more preferably 5D or less. By making the fineness 15D or less, the yarn becomes easier to twist during processing, resulting in improved bulkiness. Furthermore, the texture when made into a fabric can be made softer, and during dyeing, disperse dyes can penetrate more easily into the inside of the fibers, resulting in improved dyeability. In this specification, "single filament fineness" can be measured by the following method. Using the total fineness (dtex) and the number of single filament fibers constituting the multifilament, the single filament fineness (dtex) was calculated using the following formula: Single filament fineness (dtex) = Total fineness (dtex) / Number of single filament fibers constituting the multifilament. When converting the unit of single filament fineness to denier, the single filament fineness (dtex) was multiplied by 0.9 to obtain the single filament fineness (D).

[0034] The long-fiber crimped yarn containing polyhydroxyalkanet in this embodiment may also contain an oil. Examples of oils include silicone-based oils, vegetable oils, and synthetic ester-based oils. Specifically, examples include propyl alcohol, butyl alcohol, octyl alcohol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, higher alcohol-modified silicone, fatty acid-modified silicone, polyethylene-modified silicone, and polyether-modified silicone, and these oils may be used in combination.

[0035] The oil content of the long-fiber crimped yarn containing polyhydroxyalkanate in this embodiment is preferably 0.3% or more. By setting the oil content to 0.3% or more, tension fluctuations during the false twisting process can be suppressed, thereby preventing crimping inconsistencies and the breakage of individual fibers or yarn during the process. In addition, the oil helps to converge the individual fibers, which improves the unwinding properties of the crimped yarn. The upper limit is preferably 10% or less. By setting the oil content to 10% or less, yarn slippage during friction processing can be prevented, and good crimping properties can be achieved. In this specification, the term "oil content" can be measured by the following method. The oil content was calculated by removing the oil from the crimped yarn with petroleum ether and measuring the mass before and after drying. Specifically, about 5 g of crimped yarn was first weighed accurately, and the mass (Wa [g]) before oil removal was determined. The entire volume of the precisely weighed thread was placed in a container containing 50 ml of petroleum ether, and ultrasonic treatment was applied for 5 minutes. After discarding the petroleum ether in the container, another 50 ml of petroleum ether was added, and ultrasonic treatment was applied for another 5 minutes. After completion, the petroleum ether in the container was removed, and the thread was dried in a 50°C oven for 3 hours. The mass (Wb [g]) after drying was precisely weighed. From the obtained masses, the oil content (%) can be calculated using the following formula: Oil content (%) = {(Wa - Wb) / Wb} × 100.

[0036] Polyhydroxyalkanete long fibers can be manufactured by extruding melt-extruded polyhydroxyalkanete into a cooling medium, rapidly cooling it, centrifuging it to an arbitrary ratio both inside and outside the cooling medium, and then winding it up.

[0037] When melt-extruding, granules containing polyhydroxyalkane may be used without purification, or purified and pelletized ones may be used. Also, from the viewpoint of improving the molding processability in melt-extrusion, it may contain a plasticizer or a crystal nucleating agent, or other polymers may be blended and used. As a method for melt-extruding polyhydroxyalkane, it can be carried out using the melting technology of ordinary plastic fibers. For example, it can be carried out by heating and melting polyhydroxyalkane, applying pressure, and extruding it from an extrusion port. As an extrusion method, extrusion by a syringe or extrusion by a screw can be used. The temperature during melt-extrusion is usually above the peak start temperature of the melting point of polyhydroxyalkane measured by DSC from the viewpoint that extrusion is possible and sufficient stretching can be performed after extrusion.

[0038] The quenching temperature after melt-extrusion is preferably 30°C or lower, more preferably 20°C or lower. The lower limit is not particularly set, but from the viewpoint of economy, it can usually be carried out at -200°C or higher. By this quenching process, the melted polyhydroxyalkane becomes an amorphous fiber rich in stretchability, and deterioration over time during the process can be suppressed. The obtained fiber can be stretched and wound in a cooling solvent.

[0039] The cooling medium is not particularly limited, and examples include air, water (ice water), inert gas, and antifreeze mainly composed of ethylene glycol or propylene glycol. The cooling method is not particularly limited, and examples include a method of filling a bath with a cooling medium and passing polyhydroxyalkane through it, a method using a fluid bath, a method using a cooling plate, a method using a cooling ring, and a method using a blower. In the present invention, quenching can be carried out, for example, by extruding the melted polyhydroxyalkane into a bath filled with a cooling medium at 30°C or lower and passing it through the solvent while winding it with a roller in the bath.

[0040] Furthermore, the obtained fibers can be stretched and orientation crystallized by cold stretching them either inside or outside the cooling process, thereby increasing their mechanical strength. Cold stretching can be performed, for example, by fixing the fibers to a stretcher, and preferably by applying tension by winding them with two winding rollers while varying the speed. The stretching ratio is preferably 4 times or more, more preferably 7 times or more, and even more preferably 10 times or more. The upper limit is not particularly limited, as long as it does not cause breakage, but it can be 50 times or less. From the viewpoint of productivity, the stretching time is preferably 1 minute or less, more preferably 30 seconds or less, and there is no particular lower limit set, but in reality it can be done in 0.001 seconds or more. The stretching ratio can be measured by the following method. Ten points of 10 cm each of fiber immediately before stretching and fiber immediately after stretching are taken. The obtained fibers are conditioned overnight in an atmosphere of room temperature 23°C and humidity 50% RH, loosely stretched. The weight of 10 points of the conditioned sample is measured, and the number average value is calculated. The extension ratio is calculated by dividing the value immediately before extension by the value immediately after extension.

[0041] As for the method of imparting crimp, it may be so-called latent crimp, in which crimp is manifested by heating, stretching, solvent treatment, etc., after spinning, or crimping may be performed as a post-processing after spinning the yarn by false twisting, mechanical indentation methods such as the indentation gear method and stuffing box method, or jet indentation method. However, from the viewpoint of processability and productivity, false twisting is particularly preferred.

[0042] Another embodiment of the present invention includes a process of false twisting polyhydroxyalkanoate long fibers; the false twisting process includes a process of heating at 50°C or higher and 150°C or lower while applying twist, a process of releasing the twist, and a process of winding up the yarn after crimping. This is a method for manufacturing a polyhydroxyalkanoate long fiber crimped yarn with a crimp number of 300 / m or more and 4000 / m or less per meter as described above. The false twisting process includes a process of heating while applying twist and a process of releasing the twist. In addition, after the above process, a process of heating while the twist is released may be included. Because there is a process of releasing the twist after twisting, even for polyhydroxyalkanoate with a slow crystallization rate and where single filaments tend to stick together during spinning, the crimped single filaments can be separated from each other to increase the bulkiness, and when made into a fabric, it can have a soft texture. The flow of false twisting is usually as follows: 1. Heat while applying twist and then cool to room temperature. By heat-treating the yarn while twisted, its structure is fixed. 2. At room temperature, release the twist in the reverse direction (untwist). By releasing the twist, a crimp with bulkiness is expressed. (Optional) 3. Reheat while the crimp is expressed to stabilize the form. Stabilize the shape of the crimp and suppress dimensional changes during subsequent post-processing.

[0043] There is no particular limitation on the method of false twisting polyhydroxyalkanoate long fibers, and it can be carried out by a pin type, a friction type, a belt type, etc., but a pin type or a friction type is preferred. If it is a pin type or a friction type, by minimizing the influence of friction during spinning, it is possible to apply a strong crimp while minimizing fiber breakage.

[0044] The upper limit of the yarn temperature in the process of heating the twisted yarn is preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. If the yarn temperature in the above process is 150°C or lower, even polyhydroxyalkanetes, which are easily softened by heat, can be prevented from sticking together, and furthermore, the yarn can be twisted and untwisted with the crystalline structure minimally relaxed, so that strong crimp can be applied. The lower limit of the yarn temperature in the above process is preferably 50°C or higher, more preferably 60°C or higher. If it is below 50°C, the fibers will not soften, so the yarn cannot be twisted, and it becomes difficult to apply crimp. Also, even if crimp is applied, the crystalline structure is not fixed, and the structural maintenance force of the crimp is weak. There are no particular restrictions on the heating method, and either a contact heater or a non-contact heater may be used.

[0045] In the process of heating the twisted yarn at a temperature of 50°C to 150°C, the heating time at the heat source is preferably 5 seconds or less. The heating time during false twisting is preferably 5 seconds or less, more preferably 4 seconds or less, and even more preferably 3 seconds or less. If the heating time during false twisting is 5 seconds or less, even polyhydroxyalkanetes that are easily softened by heat can be prevented from sticking together, and furthermore, the yarn can be twisted and untwisted with the crystal structure minimally relaxed, so that strong crimp can be applied. When the heating method is contact type, the heating time is the time the yarn is in contact with the heater. When the heating method is non-contact type, the heating time is the time the yarn is running in the specified temperature atmosphere.

[0046] In the process of heating the yarn while it is twisted, the draw ratio is preferably 80% or less of the elongation of the yarn before false twisting, more preferably 60% or less, even more preferably 50% or less, and most preferably 30% or less. If the ratio of the draw ratio to the elongation of the yarn before false twisting is 80% or less, single filament breakage and yarn breakage can be suppressed even with hydroxyalkanetes whose strength has been significantly reduced by heating during false twisting. In this specification, the "ratio of the draw ratio to the elongation of the yarn before false twisting" can be measured by the following method. In accordance with the method defined in JIS L 1013, the fibers before false twisting are loosely stretched and attached to the gripping section of A&D Co., Ltd.'s Tensilon universal testing machine (RTG-1250). A tensile test is performed using a 50N load cell with a gripping distance of 30 cm and a tensile speed of 30 cm / min. The load and elongation at which the sample breaks are measured, and the elongation (K), the stretch ratio in the process of heating while twisted, and the ratio of the stretch ratio to the elongation of the yarn before false twisting (L) are calculated using the following formulas: K (%) = {Elongation at break or elongation at maximum load (mm) / gripping distance (mm)} × 100 Stretch ratio in the process of heating while twisted (%) = {Roller speed after heating (m / min) / Roller speed before heating (m / min)} × 100 L (%) = Stretch ratio in the process of heating while twisted (%) / K (%) × 100 The measurement was taken 10 times, and the average value was calculated.

[0047] With polyester yarns, it is common to use undrawn yarn and perform false twisting while drawing it. However, in the case of PHA, false twisting while drawing undrawn yarn relaxes the crystal orientation and reduces its strength. Therefore, by performing false twisting on yarn that has been pre-drawn to adjust the elongation and crystallinity to the above-mentioned levels, the yarn can be given sufficient strength.

[0048] The upper limit of the stretch ratio in the process of heating the twisted yarn is preferably 68% or less, more preferably 50% or less, more preferably 30% or less, even more preferably 20% or less, and most preferably 10% or less. If the stretch ratio is 68% or less, single filament breakage and yarn breakage during processing can be suppressed even with polyhydroxyalkanetes, which are prone to embrittlement due to secondary crystallization. There is no particular lower limit for the stretch ratio in the process of heating the twisted yarn. However, generally, when heating the twisted yarn, a vertically elongated heater is used as the heat source, and it is preferable to stretch the yarn slightly in order to process it while the twist is propagated throughout the heater. Specifically, it is preferably 1% or more, more preferably 2% or more, and even more preferably 4% or more.

[0049] In the false twisting process, suppressing fluctuations in yarn tension before the twisting section and running the yarn at a constant tension can reduce single-strand breakage or yarn breakage caused by sudden tension increases, as well as uneven twisting due to tension fluctuations in the twisting section. Specific methods for suppressing tension fluctuations are not limited to any particular method, but examples include spring tensioners, ring tensioners, washer tensioners, hysteresis tensioners, and tension equalizers. Applying an oil agent before the twisting section also improves yarn slippage during the process, enabling the suppression of tension fluctuations.

[0050] The oil may be applied to the yarn during the spinning process, or it may be applied before the twisting section during the false twisting process. There are no particular restrictions on the method of applying the oil, but specific examples include oiling guides and oiling rollers.

[0051] The step of heating the yarn in its untwisted state is optional. For yarn intended for knitting, it is necessary to eliminate the residual torque that causes the yarn to untwist, so it is preferable to have a step of heating the yarn in its untwisted state. On the other hand, for yarn intended for weaving, residual torque is not a problem, so the step of heating the yarn in its untwisted state is not necessary.

[0052] The upper limit of the yarn temperature in the process of heating the yarn after untwisting is preferably 150°C or less, more preferably 130°C or less, and even more preferably 120°C or less. If the yarn temperature in the above process is 150°C or less, even polyhydroxyalkanetes, which are prone to softening with heat, can be prevented from sticking together, and the crimped structure and twist of the yarn after untwisting can be fixed. Furthermore, the lower limit of the yarn temperature in the above process is preferably 50°C or higher, and more preferably 60°C or higher. If it is below 50°C, the fibers do not soften, making it difficult to fix the twist of the yarn, residual torque remains, and twisting occurs in the fabric when it is made into a cloth.

[0053] In the step of heating the material after untwisting, it is preferable that the tension is 10 cN or less. If the tension is 10 cN or less, the crimp is properly maintained and the structure is fixed, so the bulkiness is maintained. In this specification, "tension" was measured using an ETBP-100 manufactured by Schmidt.

[0054] The tension during the winding process is preferably 10 cN or less. By keeping the tension during winding 10 cN or less, it is possible to suppress the loss of crimp and the decrease in yarn strength due to the relaxation of the crystal structure during storage in the winded state.

[0055] The degree of crystallinity of the yarn before false twisting used in false twisting is preferably 40% or higher, more preferably 45% or higher, even more preferably 50% or higher, and most preferably 60% or higher. If the degree of crystallinity of the yarn before false twisting used in false twisting is 40% or higher, embrittlement due to secondary crystallinity is suppressed, and single-fiber breakage and yarn breakage during processing can be suppressed. Furthermore, a decrease in strength due to relaxation of the crystal structure during false twisting can also be suppressed. The upper limit is preferably 95% or lower, more preferably 90% or lower, even more preferably 85% or lower, and most preferably 80% or lower. If the degree of crystallinity of the yarn before false twisting used in false twisting is 95% or lower, the necessary elongation can be produced during processing.

[0056] The degree of crystal orientation of the α structure of the yarn before false-twisting, used in false-twisting, is preferably 65% ​​or more, more preferably 75% or more, even more preferably 80% or more, and most preferably 90% or more. The α structure referred to here is a lamellar crystal structure consisting of helical folding, and is a higher-order structure that greatly contributes to the mechanical strength of the molded article. If the degree of crystal orientation of the α structure is 65% or more, sufficient mechanical properties, especially strength, will be exhibited. In addition, the increased single-fiber strength makes it less likely for single-fiber breakage or yarn breakage to occur due to relaxation of the crystal structure by the heat applied during the false-twisting process. There is no particular upper limit, but a realistic degree of orientation is 99% or less.

[0057] The false twisting process may be carried out continuously immediately following the spinning process, or it may be performed as a separate process after the yarn has been wound and unwound. However, it is preferable to perform it as a separate process after the yarn has been wound and unwound. Performing it as a separate process allows for optimization of the false twisting speed, and precise adjustment of the heating time and the draw ratio during spinning, thereby suppressing fiber breakage during the false twisting process.

[0058] The present invention will be specifically described below with reference to examples and comparative examples. Various physical properties and performance evaluations were measured by the following methods: (1) The total fineness filament was conditioned overnight in an atmosphere of room temperature 23°C and humidity 50% RH. Ten pieces were cut from the conditioned sample at a length of 1m, under a load that was such that the crimp was fully extended but the yarn did not stretch. The weight of each piece was measured, and the average value of these weights was multiplied by 10000 to obtain the total fineness (dtex) of the sample. When converting the total fineness to denier, the total fineness (dtex) was multiplied by 0.9 to obtain the total fineness (D).

[0059] (2) Number of single filaments constituting the multifilament The cross-section of the fibers was observed using an electron microscope JSM-6510 manufactured by JEOL Ltd., and the number of single filaments was measured as the number of single filaments constituting the multifilament.

[0060] (3) Single filament fineness Using the total fineness (dtex) obtained in (1) and (2) above and the number of single filament fibers constituting the multifilament, the single filament fineness (dtex) was calculated using the following formula: Single filament fineness (dtex) = Total fineness (dtex) / Number of single filament fibers constituting the multifilament. When converting the unit of single filament fineness to denier, the single filament fineness (dtex) was multiplied by 0.9 to obtain the single filament fineness (D).

[0061] (4) Breaking strength and breaking elongation In accordance with the method defined in JIS L 1013, fiber samples were attached to the grips of an A&D Company, Limited Tensilon universal tester (RTG-1250) with a load applied such that the crimp was fully extended but the yarn did not stretch. Tensile tests were performed using a 50N load cell with a gripping distance of 30 cm and a tensile speed of 30 cm / min. The load and elongation at which the sample broke were measured at 10 points, and the strength and elongation were calculated using the following formulas: Strength (cN / dtex) = Strength at break or strength at maximum load (cN) / Total fineness (dtex) Elongation (%) = {Elongation at break or elongation at maximum load (mm) / Grip spacing (mm)} × 100 The average of these values ​​was taken as the strength (average strength) and elongation of the sample. If the breaking strength was less than the strength at maximum load, the strength at maximum load and the elongation at that time were measured.

[0062] (5) Crystallinity The degree of crystallinity is measured using a differential scanning calorimeter (Perkin Elmer, DSC8500) equipped with an intracooler. The measurement atmosphere is nitrogen (50 ml / min), and the temperature is raised from -50°C to 200°C at a rate of 10°C / min, and the sample is held for 1 minute to completely melt it. The melting point peak appearing in the measured DSC curve (thermogram) is integrated to calculate the melting energy. If the melting energy is M (J / g), the degree of crystallinity N (%) is calculated using the following formula. The sample is approximately 1 mg, and an aluminum sample pan (Hitachi High-Tech Al autosampler sample container, Φ6.8 H2.5 mm) is used. Indium is used for temperature calibration. The degree of crystallinity was calculated from the following formula: N (%) = M / (146 × (100 - copolymerization ratio of the sample) / 100) × 100 (%). The measurement was taken three times, and the average value was calculated.

[0063] (6) α-crystal orientation Using an X-ray structure evaluation device (Rigaku, SmartLab) and a multidimensional pixel array detector (Rigaku, HiPix-3000), the X-ray wavelength was set to 0.1 nm, the camera length to 27 mm, and the exposure time to 30 min. The fiber sample was placed perpendicular to the X-ray beam and parallel to the detector, under a load that fully extended the crimp but prevented the yarn from stretching, and a two-dimensional diffraction pattern was obtained. In the wide-angle X-ray diffraction (WAXD) measurement, a region containing a specific diffraction point (020 plane) in the WAXD image was selected in a ring shape, and all diffraction intensities with the same azimuthal angle were integrated. A one-dimensional azimuthal profile was created by plotting this intensity against the azimuthal angle. At the locations where diffraction spots exist, a curve resembling a normal distribution with peaks is obtained, and its full width at half maximum (FWHM: the peak width at half the height of the peak) was measured. The degree of orientation (%) was calculated using the following formula: Degree of orientation (%) = (180 - FWHM) / 180 × 100 (%). Five measurements were taken, and the average value was used.

[0064] (7) Ratio of X-ray diffraction intensity of β structure to α structure (Iβ / Iα) Using an X-ray structure evaluation device (Rigaku, SmartLab) and a multidimensional pixel array detector (Rigaku, HiPix-3000), the X-ray wavelength was set to 0.1 nm, the camera length to 27 mm, and the exposure time to 30 min. The fiber sample was placed perpendicular to the X-ray beam and parallel to the detector with a load that fully extended the crimp but did not stretch the thread, and a two-dimensional diffraction pattern was obtained. When the diffraction intensity distribution in the equatorial direction of the two-dimensional diffraction pattern is measured, the diffraction intensity is composed of scattering by amorphous materials and diffraction by crystals. Diffraction by crystals includes diffraction of α and β structures, each producing diffraction at specific positions, and the diffraction intensity is proportional to the amount of crystals. Therefore, by taking the ratio of the diffraction intensity based on the α structure to the diffraction intensity based on the β structure, an index regarding the amount of β structure can be obtained. However, because the intensity based on amorphous scattering interferes, it is necessary to remove the influence of the intensity based on amorphous scattering in order to determine the amount of β structure in the crystal. Since the intensity based on amorphous scattering is observed as a broader baseline elevation than the intensity based on crystal diffraction, the line connecting 2θ = 15° and 21°, where the influence of diffraction from the crystal is small, is considered to be the intensity based on amorphous scattering, and this amount is subtracted from the diffraction intensity. In the subsequent diffraction intensity distribution, the maximum value between 2θ = 15° and 18° is taken as the diffraction intensity from α structure (Iα), and the maximum value between 18° and 21° is taken as the diffraction intensity from β structure (Iβ). The amount of β-type crystals can be evaluated by relatively comparing Iα and Iβ, and a larger ratio of Iβ / Iα indicates that a large amount of β-type crystals are present. The measurement was performed five times, and the average value was taken.

[0065] (8) Oil content The oil content was calculated by removing the oil from the fiber sample using petroleum ether and measuring the mass before and after drying. Specifically, first, approximately 5 g of the fiber sample was accurately weighed to determine the mass before oil removal (Wa [g]). The weighed yarn was placed in a container containing 50 ml of petroleum ether, and ultrasonic treatment was applied for 5 minutes. After discarding the petroleum ether in the container, another 50 ml of petroleum ether was added, and ultrasonic treatment was applied for another 5 minutes. After completion, the petroleum ether in the container was removed, and the sample was dried in a 50°C oven for 3 hours. The mass after drying (Wb [g]) was accurately weighed. From the masses obtained, the oil content (%) could be calculated using the following formula: Oil content (%) = {(Wa - Wb) / Wb} × 100. The measurement was performed three times, and the average value was taken.

[0066] (9) The cross-section of the fiber after the fiber adhesion processing was observed using a JEOL Ltd. electron microscope JSM-6510, and the number of single fibers constituting the multifilament was taken as the number of single fibers before processing. Next, a 10 cm section of the processed fiber was cut and separated into separate fiber bundles. Specifically, if the single fibers were adhered to each other, the adhered bundle was counted as one fiber bundle, and if the single fibers were not adhered to each other, each single fiber was counted as one fiber bundle. The number of separated fiber bundles was judged in three stages according to the following evaluation criteria: "◎": The number of separated fiber bundles is 100% of the number of single fibers before processing. "△": The number of separated fiber bundles is 50% or more and less than 100% of the number of single fibers before processing. "×": The number of separated fiber bundles is 0% or more and less than 50% of the number of single fibers before processing.

[0067] (10) Amount of single-fiber breakage A 10 cm section of the processed fiber was cut and observed using a digital microscope (Keyence VHX-7000, stage: VHX-S770, lens: VH-Z100R) to visually count the number of single-fiber breaks that had resulted in fuzz. The results were then judged on a four-point scale according to the following evaluation criteria: "◎": 0 to 5 fuzzes "〇": 6 to 10 fuzzes "△": 11 to 15 fuzzes "×": 16 or more fuzzes

[0068] (11) Number of crimps (pieces / m) According to the method defined in JIS L 1015, the number of crimps was calculated by drawing 25 mm interval lines on a smooth, glossy piece of paper, drawing one single filament from each of 30 random locations on the fiber sample, and attaching each drawn single filament to both ends with adhesive, leaving a slack of 25 ± 5% relative to the interval. Each of these single filaments was attached to the grips of a crimp tester (Intec SE-9N), cutting the paper piece, and reading the distance between the grips (interval distance) (mm) when the initial load was applied to the sample. The average number of crimps per 25 mm at that time was then calculated. The initial load was set to 0.18 mN × single filament fineness (dtex) / 100, and the number of crimps was calculated by counting all the peaks and valleys and dividing by 2. The crimp count (creps / m) was calculated by multiplying this average value by 40.

[0069] (12) Structural Retention Force of Crimp The structural retention force of crimp correlates with yield strength and yield elongation. Yield strength and yield elongation were evaluated using the following method. Following the method defined in JIS L 1013, fiber samples were attached to the grips of an A&D Company, Limited Tensilon universal testing machine (RTG-1250) with a load applied such that the crimp was fully extended but the yarn did not stretch. A tensile test was performed using a 50N load cell with a gripping distance of 30 cm and a tensile speed of 30 cm / min. The load and elongation at which the sample broke were measured, and the yield elongation and yield strength were calculated using the following formulas: Yield strength (cN / dtex) = Stress at yield point (cN) / Fineness of sample (dtex) Yield elongation (%) = {Elongation at yield point (mm) / Grip spacing (mm)} × 100 The evaluation was performed 10 times, and the average value of these results was used as the yield strength (cN / dtex) and yield elongation (%) of the sample. The structural retention force of the crimp was evaluated on a five-point scale based on the yield strength and yield elongation. "5": No yield point exists. "4": Yield strength of 0.7 cN / dtex or more and yield elongation of 10% or more "3": Yield strength less than 0.7 cN / dtex and yield elongation of 10% or more, or yield strength of 0.7 cN / dtex or more and yield elongation of 5% or more and less than 10% "2": Yield strength less than 0.7 cN / dtex and yield elongation of 5% or more and less than 10%, or yield strength of 0.7 cN / dtex or more and yield elongation of less than 5% "1": Yield strength less than 0.7 cN / dtex and yield elongation of less than 5% "1" has a low maximum reversible elongation and low crimp structure retention force. The closer to "5" the higher the maximum reversible elongation and the stronger the crimp structure retention force.

[0070] (13) Texture after fabrication Fiber samples were fed into a tubular knitting machine (Eiko Sangyo Co., Ltd. Single-cut test tubular knitting machine NCR-ES), and tubular knitted fabric was produced by adjusting the machine to a gauge of 50. Five subjects were asked to put their hands through the obtained tubular knitted fabrics and were each given a questionnaire about their softness. Fabrics that felt soft when the hand was put through were evaluated as having excellent softness. If five people answered that it was excellent, it was judged as "◎", if four people answered as "〇", if three people answered as "△", and if two or fewer people answered as "×".

[0071] (14) Ratio of stretch ratio to elongation of yarn before false twisting According to the method defined in JIS L 1013, the fiber before false twisting is loosely stretched and attached to the gripping section of A&D Co., Ltd.'s Tensilon universal testing machine (RTG-1250), and a tensile test is performed using a 50N load cell with a gripping distance of 30 cm and a tensile speed of 30 cm / min. The load and elongation at which the sample breaks are measured, and the elongation (K), the stretch ratio in the process of heating while twisted, and the ratio of the stretch ratio to the elongation of yarn before false twisting (L) are calculated using the following formulas: K (%) = {Elongation at break or elongation at maximum load (mm) / gripping distance (mm)} × 100 Stretch ratio in the process of heating while twisted (%) = {Roller speed after heating (m / min) / Roller speed before heating (m / min)} × 100 L (%) = Stretch ratio during the heating process in the twisted state (%) / K (%) × 100. The measurement was taken 10 times and the average value was used.

[0072] [Preparation of drawn yarns 1-8] Using the microorganism Cupriavidus necator H16 strain (ATCC17699 strain) as the microorganism that produces PHAs, PHBV with a copolymer ratio of 1.0%, P3HB4HB with a copolymer ratio of 6.0%, and P3HB were prepared by appropriately adjusting the raw materials and culture conditions. In addition, using the Aeromonas caviae strain (ATCC15468 strain), PHBH with a copolymer ratio of 4.0% was prepared by appropriately adjusting the raw materials and culture conditions. These resins were melt-extruded in a melt extruder (AIKI Riotec ALM-S1000) heated to 170°C with a residence time of 600 seconds. The extruded material was spun using a nozzle with a pore diameter of 0.23 mm and 36 holes. The material was passed through an air gap section in 3 seconds while being drafted in the air gap section, cooled in a cooling process at 5°C, cold-stretched in the cooling process, further stretched at room temperature, and finally wound on a winding machine to produce drawn yarns 1 to 8 consisting of 10,000 m of continuous multifilament long fibers. The manufacturing conditions and properties of the produced drawn yarns are shown in Table 1 below.

[0073]

[0074] [Examples 1-5, 8-15, 18-22, Comparative Examples 1-6] Using a false twist tester (AIKI Riotec ALM-DTY), false twist yarns were produced from the prepared drawn yarns by pin-type false twist processing under the crimping conditions shown in Tables 2-4 below. Tricol M-2080, manufactured by Matsumoto Oil & Fat Co., Ltd., was used as the lubricant. After production, various physical properties and performance evaluations were performed as shown in Tables 2-4 below.

[0075] [Examples 6, 7, 16, 17] Using a false twist tester (AIKI Riotec ALM-DTY), the prepared drawn yarns were subjected to friction-type false twisting to produce false twisted yarns under the crimping conditions shown in Tables 2 and 3 below. The lubricant used was Tricol M-2080 manufactured by Matsumoto Oil & Fat Co., Ltd. After production, various physical properties and performance evaluations were performed as shown in Tables 2 and 3 below. In Comparative Example 2, processing was difficult due to single-yarn breakage, so evaluations of crimp count, structural retention strength by measuring crimp density, fabrication, and texture were not performed.

[0076]

[0077]

[0078]

[0079] The long-fiber crimped yarn containing polyhydroxyalkanete of the present invention has sufficient biodegradability in marine environments and possesses excellent texture when fabricated. Furthermore, the method for producing the crimped yarn of the present invention enables the stable production of fibers with a high crimp count. Therefore, the long-fiber crimped yarn containing polyhydroxyalkanete of the present invention has excellent characteristics in terms of environmental impact, physical properties, and economic advantages, and can be used in a wide variety of applications.

Claims

1. A polyhydroxyalkaneate filament crimped yarn having a crimp count of 300 or more per meter and 4000 or less per meter.

2. The polyhydroxyalkanet long fiber crimped yarn according to claim 1, wherein the degree of crystal orientation of the α structure of the polyhydroxyalkanet is 65% or more.

3. The polyhydroxyalkanet long fiber crimped yarn according to claim 2, wherein the degree of crystal orientation of the α structure of the polyhydroxyalkanet is 75% or more.

4. The polyhydroxyalkaneate long fiber crimped yarn according to claim 1 or 2, wherein the number of crimps per meter is 510 or more.

5. A crimped polyhydroxyalkaneate filament yarn according to claim 1 or 2, which is a false-twist yarn.

6. The polyhydroxyalkane long fiber crimped yarn according to claim 1 or 2, wherein the degree of crystallinity of the polyhydroxyalkane is 40% or more.

7. The polyhydroxyalkanete long fiber crimped yarn according to claim 1 or 2, wherein the X-ray diffraction intensity ratio Iβ / Iα of the β structure and α structure of the polyhydroxyalkanete is 0.6 or less.

8. The polyhydroxyalkanate long fiber crimped yarn according to claim 1 or 2, wherein the polyhydroxyalkanate is a homopolymer of 3-hydroxybutyrate, or a copolymer consisting of a first monomer unit of 3-hydroxybutyrate and a second monomer unit.

9. The polyhydroxyalkaneate long fiber crimped yarn according to claim 8, wherein the copolymerization ratio of the second monomer units is 15 mol% or less.

10. The polyhydroxyalkaneate filament crimped yarn according to claim 1 or 2, wherein the single filament fineness is 15 denier or less.

11. The polyhydroxyalkaneate long fiber crimped yarn according to claim 1 or 2, wherein the long fiber crimped yarn is a multifilament, and the number of single fibers constituting the multifilament is 10 or more.

12. The polyhydroxyalkanate long fiber crimped yarn according to claim 1 or 2, wherein the oil content is 0.3% or more and 10% or less.

13. A method for producing a crimped polyhydroxyalkanate filament yarn, comprising the steps of: false-twisting a polyhydroxyalkanate filament; wherein the false-twisting step includes the steps of heating the twisted yarn at 50°C to 150°C, untwisting the yarn, and winding up the yarn after crimping, the number of crimps per meter being 300 or more and 4000 or less.

14. The manufacturing method according to claim 13, wherein the polyhydroxyalkaneate long fiber subjected to the false-twisting process has a crystallinity of 40% or more and a degree of crystal orientation of the α structure of 65% or more.

15. The manufacturing method according to claim 13 or 14, wherein the false twisting process in the false twisting step is carried out using a pin-type, friction-type, or belt-type false twisting device.

16. The manufacturing method according to claim 13 or 14, wherein the heating time at the heat source in the step of heating the twisted material at 50°C to 150°C is 5 seconds or less.

17. The manufacturing method according to claim 13 or 14, wherein the stretch ratio in the step of heating the yarn in the twisted state is 80% or less of the elongation of the yarn before false twisting.

18. The manufacturing method according to claim 17, wherein the stretching ratio is 68% or less.

19. The manufacturing method according to claim 13 or 14, wherein the false twisting process includes a tension fluctuation suppression step prior to the twisting section.

20. The manufacturing method according to claim 13 or 14, further comprising the step of applying an oil agent before the twisting portion in the false twisting process.

21. The manufacturing method according to claim 13 or 14, comprising the step of heating the untwisted strands at a temperature of 50°C to 150°C.

22. The manufacturing method according to claim 21, wherein the tension in the step of heating the material at 50°C to 150°C in the untwisted state is 10 cN or less.

23. The manufacturing method according to claim 13 or 14, wherein the tension in the winding step is 10 cN or less.

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