Fiber and non-woven fabric

Abstract

Provided is a fiber containing a poly (3-hydroxyalkanoate)-based resin, the fiber containing a poly (3-hydroxyalkanoate)-based resin containing a 3-hydroxybutyrate unit, the fiber being suppressed in melt adhesion during the production of the fiber and being capable of being thermally fused under low-temperature conditions during thermal processing of the fiber. The present invention is a fiber having a core-sheath structure including a core part and a sheath part, the core part and the sheath part each containing a poly (3-hydroxyalkanoate)-based resin including a 3-hydroxybutyrate unit, the average molar content of 3-hydroxybutyrate units in the poly (3-hydroxyalkanoate)-based resin in the core part is greater than the average molar content of 3-hydroxybutyrate units in the poly (3-hydroxyalkanoate)-based resin in the sheath part.

Description

Technical Field

[0001] This invention relates to fibers and nonwoven fabrics. Background Technology

[0002] In recent years, plastic waste has presented several problems, including its impact on ecosystems, the production of harmful gases during combustion, and global warming due to the large amount of heat generated, thus placing a significant burden on the Earth's environment. 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 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 polyhydroxyalkanoate resins, have attracted attention as biodegradable plastics produced by microorganisms using plant-derived raw materials as carbon sources.

[0005] Patent document 1 discloses a microbial decomposable composite fiber, which has poly(β-hydroxyalkanoate) or its copolymer as the core component and poly-ε-caprolactone and / or poly-β-propiolactone as the sheath component.

[0006] Patent document 2 discloses a foamed defibrilable molded article comprising the following copolymer (A) and copolymer (B).

[0007] (A) A copolymer comprising the following structural units (a1) and (a2) at the following ratio (the total of (a1) and (a2) is set at 100 mol%).

[0008] (a1) 3-hydroxybutyrate structural unit

[0009] 92 mol% or more and 98 mol% or less

[0010] (a2) [-O-R1-CO-] shows the structural unit

[0011] 2 mol% or more and 8 mol% or less

[0012] (R1 represents a straight-chain or branched alkyl group with 3 or more but less than 17 carbon atoms.)

[0013] (Among them, structural unit (a2) does not contain 3-hydroxybutyrate structural units.)

[0014] (B) A copolymer comprising the following structural units (b1) and (b2) at the following ratio (the total of (b1) and (b2) is set to 100 mol%).

[0015] (b1) 3-Hydroxybutyrate structural unit

[0016] 85 mol% or more and less than 92 mol%

[0017] (b2) The structural unit shown is [-O-R2-CO-].

[0018] More than 8 mol% and less than 15 mol%

[0019] (R2 represents a straight-chain or branched alkyl group with 3 or more but less than 17 carbon atoms.)

[0020] (Among them, structural unit (b2) does not contain 3-hydroxybutyrate structural units.)

[0021] Existing technical documents

[0022] Patent documents

[0023] Patent Document 1: Japanese Patent Application Publication No. 5-93318

[0024] Patent Document 2: Japanese Patent Application Publication No. 2023-49669 Summary of the Invention

[0025] The problem that the invention aims to solve

[0026] However, fibers sometimes melt and stick during manufacturing, or cannot achieve sufficient thermal bonding at low temperatures during thermal processing, making thermal processing difficult.

[0027] Therefore, the objective of this invention is to provide a fiber containing a poly(3-hydroxyalkanoate) resin and a nonwoven fabric having the fiber, wherein the fiber containing the poly(3-hydroxyalkanoate) resin exhibits suppressed melt adhesion during fiber manufacturing and can achieve thermal fusion at low temperatures when the fiber is thermally processed, the fiber containing a poly(3-hydroxyalkanoate) resin comprising 3-hydroxybutyrate units.

[0028] Problem Solving Methods

[0029] This invention relates to a fiber having a core-sheath structure comprising a core and a sheath.

[0030] The core and sheath portions described above each contain a poly(3-hydroxyalkanoate) resin comprising 3-hydroxybutyrate units.

[0031] The average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core is greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath.

[0032] In addition, the present invention also relates to a method for manufacturing fibers, wherein the above-mentioned fibers are obtained by melt spinning a core material composition and a sheath material composition by using a core-sheath type composite spinning nozzle.

[0033] Furthermore, the present invention also relates to a nonwoven fabric comprising the aforementioned fibers.

[0034] The effects of the invention

[0035] According to the present invention, a fiber containing a poly(3-hydroxyalkanoate) resin and a nonwoven fabric having the fiber are provided, wherein the fiber containing the poly(3-hydroxyalkanoate) resin exhibits suppressed melt adhesion during fiber manufacturing and can achieve thermal fusion at low temperature when the fiber is thermally processed, the fiber containing a poly(3-hydroxyalkanoate) resin comprising 3-hydroxybutyrate units. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the cross-section of a single fiber of the fiber in this embodiment.

[0037] Symbol Explanation

[0038] 1: Single fiber

[0039] 10: Core

[0040] 20: Sheath Detailed Implementation

[0041] Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

[0042] <Fibers in this embodiment>

[0043] The fiber in this embodiment has a core-sheath structure that includes a core and a sheath.

[0044] The core and sheath portions described above each contain a poly(3-hydroxyalkanoate) resin (hereinafter also referred to as "P3HA resin", "P3HA", "poly(3-hydroxybutyrate) resin", or "P3HB resin") containing 3-hydroxybutyrate units.

[0045] The average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core is greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath.

[0046] The fiber of this embodiment has such a structure that melt adhesion is suppressed during fiber manufacturing, and when the fiber is thermally processed, it is a fiber containing a poly(3-hydroxyalkanoate) resin that can achieve thermal fusion at low temperature.

[0047] The fiber in this embodiment can be a multifilament having multiple single fibers, or it can be a single fiber. From the viewpoint of being soft, supple, and suitable for use in nonwoven fabrics, multifilament is preferred.

[0048] The aforementioned single fiber is a core-sheath composite fiber.

[0049] Figure 1 This is a schematic diagram of a cross-section (a cross-section perpendicular to the length direction of the single fiber) of the core-sheath composite fiber that is the fiber in this embodiment.

[0050] like Figure 1 As shown, the single fiber 1, which is a core-sheath composite fiber, includes a core 10 and a sheath 20. In the cross-section of this core-sheath composite fiber (a cross-section perpendicular to the length direction of the core-sheath composite fiber), the core is preferably located inside the sheath. Furthermore, in the cross-section (a cross-section perpendicular to the length direction of the core-sheath composite fiber), the core-sheath composite fiber can be a concentric structure where the center of the core is aligned with the center of the core-sheath composite fiber, or it can be an eccentric structure where the center of the core is not aligned with the center of the core-sheath composite fiber and is offset from the center.

[0051] The cross-sectional shape of the single fiber 1 and the core 10, which are core-sheath composite fibers, is not particularly limited. For example, it can be circular or irregular in shape. Examples of irregular shapes include: elliptical, intersecting circular, cocoon-shaped, daruma-shaped, dog bone-shaped, and ribbon-shaped. The cross-sectional shape of the core-sheath composite fiber can be the same as (similar to) the cross-sectional shape of the core or different.

[0052] In this embodiment, the long axis direction of the single fiber cross section is consistent with the long axis direction of the core cross section.

[0053] exist Figure 1 In this configuration, the cross-sectional shape of the single fiber 1, which is a core-sheath composite fiber, and the cross-sectional shape of the core 10 are both circular, and the core 10 is arranged in a concentric circle with the single fiber 1, which is a core-sheath composite fiber.

[0054] The cross-sectional shape of the single fiber and the core of the core-sheath composite fiber can be controlled when making fibers using a core-sheath type composite spinning nozzle with a nozzle orifice having a shape close to the target cross-sectional shape by using a core-sheath type composite spinning nozzle with a nozzle orifice having a shape close to the target cross-sectional shape.

[0055] In this embodiment, the core-sheath ratio (the ratio of core 10 to sheath 20) in the cross-section of the fiber (the cross-section perpendicular to the length direction of the fiber, i.e., the cross-section perpendicular to the length direction of the single fiber) is not particularly limited. However, from the viewpoints of complex appearance, spinning, and cross-sectional stability, the area ratio of core 10 to sheath 20 is preferably in the range of 1:9 to 9:1, more preferably 2:8 to 8:2, and even more preferably 3:7 to 7:3.

[0056] In other words, the area ratio of the core portion 10 to the sheath portion 20 in the cross-section of the fiber is preferably core / sheath = 9 / 1 to 1 / 9, more preferably core / sheath = 8 / 2 to 2 / 8, and even more preferably core / sheath = 7 / 3 to 3 / 7.

[0057] The core-sheath ratio can be determined using the method described in the embodiments below.

[0058] The fiber in this embodiment contains a polymer component.

[0059] The polymer components described above contain poly(3-hydroxyalkanoate) resins comprising 3-hydroxybutyrate units.

[0060] In addition to the poly(3-hydroxyalkanoate) resins mentioned above, the polymer components may also contain other polymers.

[0061] The above-mentioned poly(3-hydroxyalkanoate) resins are biodegradable polymers.

[0062] It should be noted that "biodegradability" in this embodiment refers to the property of being able to decompose into low-molecular-weight compounds by microorganisms in nature. Specifically, the presence or absence of biodegradability is determined by tests suitable for various environments, such as ISO 14855 (compost) and ISO 14851 (activated sludge) under aerobic conditions, and ISO 14853 (aqueous phase) and ISO 15985 (solid phase) under anaerobic conditions. Furthermore, the decomposition ability of microorganisms in seawater can be evaluated by measuring biochemical oxygen demand (BOD).

[0063] The above-mentioned poly(3-hydroxyalkanoate) resins include both homopolymers and copolymers.

[0064] The poly(3-hydroxyalkanoate) resins mentioned above are preferably copolymers.

[0065] Examples of the above-mentioned poly(3-hydroxyalkyl ester) resins include, for example, P3HB, P3HB3HH, P3HB3HV, P3HB4HB, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), etc.

[0066] P3HB refers to poly(3-hydroxybutyrate) as a homopolymer.

[0067] P3HB3HH refers to poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), which is also a copolymer resin of (3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0068] P3HB3HV refers to poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

[0069] P3HB4HB refers to poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

[0070] It should be noted that P3HB has the function of promoting the crystallization of P3HB itself and poly(3-hydroxyalkanoate) resins other than P3HB. Therefore, the above-mentioned poly(3-hydroxyalkanoate) resins preferably contain P3HB.

[0071] As for the above-mentioned poly(3-hydroxyalkanoate) resins, from the viewpoint of balancing excellent biodegradability and molding processability, P3HB, P3HB3HH, P3HB3HV, P3HB4HB, etc. are preferred, but there are no particular limitations.

[0072] Furthermore, from the viewpoint of improving the strength of the fibers in this embodiment and improving the molding processability, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH) is preferred as the above-mentioned poly(3-hydroxyalkanoate) resin.

[0073] The average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core is greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath.

[0074] In this application, the "average molar content of 3-hydroxybutyrate units in poly(3-hydroxyalkanoate) resins" is also referred to as the "average molar content of 3HB in P3HA resins".

[0075] From the viewpoint of further suppressing fusion bonding during fiber manufacturing and enabling thermal fusion bonding at lower temperatures during fiber thermal processing, the difference between the average molar content of 3HB in the P3HA resin in the core and the average molar content of 3HB in the P3HA resin in the sheath is preferably 0.2 to 9.0 mol%, more preferably 0.4 to 7.0 mol%, even more preferably 0.5 to 4.5 mol%, particularly preferably 1.0 to 4.0 mol%, and most preferably 1.5 to 3.5 mol%.

[0076] It should be noted that the difference between the average molar content of 3HB in the P3HA resin in the core and the average molar content of 3HB in the P3HA resin in the sheath is obtained by subtracting the average molar content of 3HB in the P3HA resin in the sheath from the average molar content of 3HB in the P3HA resin in the core.

[0077] In the case of the fiber of this embodiment, by making the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core portion greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath portion, melt adhesion can be suppressed during fiber manufacturing, and thermal fusion can be achieved at low temperature during heat processing of the fiber.

[0078] From the viewpoint that it is possible to further suppress melt adhesion during fiber manufacturing and to achieve heat fusion at a further low temperature when the fiber is heat-processed, the fiber of this embodiment preferably comprises a copolymer (A) in which the molar ratio of monomers of 3-hydroxybutyrate units to other hydroxyalkanoate units is 99 / 1 to 93 / 7, and a copolymer (B) in which the molar ratio of monomers of 3-hydroxybutyrate units to other hydroxyalkanoate units is 92 / 8 to 76 / 24.

[0079] In the copolymer (A) above, the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units is 3-hydroxybutyrate units / other hydroxyalkanoate units = 99 / 1 to 93 / 7, preferably 98 / 2 to 93 / 7, and more preferably 97 / 3 to 93 / 7.

[0080] In the copolymer (B) described above, the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units is 3-hydroxybutyrate units / other hydroxyalkanoate units = 92 / 8 to 76 / 24, preferably 91 / 9 to 80 / 20, and more preferably 90 / 10 to 85 / 15.

[0081] The average molar content of 3-hydroxybutyrate units in poly(3-hydroxyalkanoate) resins and the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units in poly(3-hydroxyalkanoate) resins (3-hydroxybutyrate units / other hydroxyalkanoate units) can be determined as follows.

[0082] 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 20 mg of dried P3HA resin to obtain a sample. The sample was sealed and heated at 100°C for 140 minutes under sealed conditions to obtain the first reaction solution containing methyl ester, which is a decomposition product of P3HA resin.

[0083] Then, the first reaction solution is cooled, and 1.5g of sodium bicarbonate is added to the cooled first reaction solution in small amounts each time for neutralization. The mixture is left to stand until the production of carbon dioxide stops, thus obtaining the second reaction solution.

[0084] Further, the second reaction solution was thoroughly mixed with 4 mL of diisopropyl ether to obtain a mixture.

[0085] Next, the mixture was centrifuged to obtain the supernatant.

[0086] Then, by capillary gas chromatography under the following conditions, the monomer unit composition of the above decomposition products in the supernatant can be analyzed to determine the average molar content of 3-hydroxybutyrate units in poly(3-hydroxyalkanoate) resins and the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units in poly(3-hydroxyalkanoate) resins (3-hydroxybutyrate units / other hydroxyalkanoate units).

[0087] Gas chromatograph: Shimadzu GC-17A

[0088] Capillary column: NEUTRA BOND-1 manufactured by GL Science (column length: 25m, column inner diameter: 0.25mm, liquid film thickness: 0.4μm)

[0089] Carrier gas: He

[0090] Column inlet pressure: 100 kPa

[0091] Sample volume: 1 μL

[0092] From the viewpoint that it can further suppress fusion bonding during fiber manufacturing and enable thermal bonding at a further low temperature when the fiber is thermally processed, the fiber of this embodiment preferably contains 5 to 40% by weight of the copolymer (B) relative to 100% by weight of the poly(3-hydroxyalkanoate) resin, more preferably 10 to 35% by weight, and even more preferably 12 to 30% by weight.

[0093] From the viewpoint that thermal fusion can be achieved at a further low temperature when the fiber is thermally processed, the sheath preferably contains the copolymer (B).

[0094] Furthermore, from the viewpoint that it can further suppress fusion bonding during fiber manufacturing and enable thermal fusion bonding at a further low temperature when the fiber is thermally processed, the sheath portion more preferably includes the copolymer (A) and the copolymer (B).

[0095] From the viewpoint of further suppressing melt adhesion during fiber manufacturing, the core preferably contains the copolymer (A).

[0096] The fiber in this embodiment preferably contains 50% by weight or more of a poly(3-hydroxyalkanoate) resin, more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0097] In addition, the fiber in this embodiment preferably contains 50% by weight or more of copolymer (A) and copolymer (B), more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0098] Other polymers are preferably biodegradable.

[0099] Other biodegradable polymers include, for example, polycaprolactone, polylactic acid, polybutylene succinate, polybutylene adipate, polybutylene terephthalate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, modified starch, cellulose acetate, chitosan, and poly(4-hydroxyalkanoate) resins.

[0100] The aforementioned polycaprolactone is a polymer formed by the ring-opening polymerization of ε-caprolactone.

[0101] The polymer components mentioned above may include one other polymer, or more than two.

[0102] The fiber in this embodiment contains a biodegradable polymer, which can easily decompose in the environment even if it is discarded, thus reducing the burden on the environment.

[0103] The fibers in this embodiment may further contain additives.

[0104] 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.

[0105] In order to promote the crystallization of poly(3-hydroxyalkanoate) resin, the fiber of this embodiment preferably contains a crystallizing nucleating agent.

[0106] The aforementioned nucleating agent is a compound that promotes the crystallization of poly(3-hydroxyalkanoate) resins. Furthermore, the melting point of the aforementioned nucleating agent is higher than that of poly(3-hydroxyalkanoate) resins.

[0107] Examples of nucleating agents for the aforementioned crystallization include: inorganic substances (boron nitride, titanium dioxide, talc, layered silicates, calcium carbonate, sodium chloride, and metal phosphates, etc.); sugar alcohols derived from natural sources (pentaerythritol, erythritol, galactitol, mannitol, and arabinitol, etc.); polyvinyl alcohol; chitin; chitosan; polyethylene oxide; aliphatic carboxylates; aliphatic alcohols; aliphatic carboxyl esters; and dicarboxylic acid derivatives (dimethyl adipate, dibutyl adipate, diisodecyl adipate, and sebacic acid). Dibutyl ester; cyclic compounds having functional groups selected from C=O, NH, S and O within the molecule (such as indigo, quinacridone and quinacridone fuchsin); sorbitol derivatives (such as dibenzylidene sorbitol and bis(p-methylbenzylidene)sorbitol); compounds containing nitrogen-containing heterocyclic aromatic cores (such as pyridine ring, triazine ring and imidazole ring) (such as pyridine, triazine and imidazole); phosphate ester compounds; diamides of higher fatty acids; metal salts of higher fatty acids; and branched polylactic acid, etc.

[0108] In addition, P3HB, as the aforementioned poly(3-hydroxyalkanoate) resin, can be used as a crystallization nucleating agent.

[0109] These can be used individually or in combination of two or more.

[0110] From the viewpoint of improving the crystallization rate of poly(3-hydroxyalkanoate) resins and considering compatibility and affinity with poly(3-hydroxyalkanoate) resins, sugar alcohol compounds, polyvinyl alcohol, chitin, and chitosan are preferred as the above-mentioned crystallizing nucleating agents.

[0111] In addition, pentaerythritol is preferred among the sugar alcohol compounds.

[0112] The above-mentioned nucleating agent preferably has a crystalline structure at room temperature (25°C).

[0113] By enabling the above-mentioned nucleating agent to have a crystalline structure at room temperature (25°C), the crystallization of poly(3-hydroxyalkanoate) resins is further promoted.

[0114] In addition, the nucleating agent that has a crystalline structure at room temperature (25°C) is preferably in powder form at room temperature (25°C).

[0115] Furthermore, the average particle size of the nucleating agent, which is in powder form at room temperature (25°C), is preferably 10 μm or less.

[0116] The content of the nucleating agent in the fiber of this embodiment is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and even more preferably 0.5 parts by weight or more, relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin. By setting the content of the nucleating agent in the fiber of this embodiment to 0.05 parts by weight or more relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, it has the advantage of being able to further promote the crystallization of the poly(3-hydroxyalkanoate) resin.

[0117] Furthermore, relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the content of the nucleating agent in the fiber of this embodiment 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. By setting the content of the nucleating agent in the fiber of this embodiment to 10 parts by weight or less relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the viscosity of the melt can be reduced when the melt is used to produce fibers by the melt spinning method described later. As a result, it has the advantage of being easy to produce fibers.

[0118] It should be noted that P3HB is a poly(3-hydroxyalkanoate) resin and can function as a crystal nucleating agent. Therefore, when the fiber contains P3HB, the amount of P3HB is included in the amount of poly(3-hydroxyalkanoate) resin and also in the amount of crystal nucleating agent.

[0119] The fibers in this embodiment may contain a lubricant.

[0120] Examples of such lubricants include compounds having amide bonds.

[0121] 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.

[0122] Relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin described above, the lubricant content in the fiber of this embodiment is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and even more preferably 0.5 parts by weight or more. By setting the lubricant content in the fiber of this embodiment to 0.05 parts by weight or more relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, it has the advantage of excellent lubricity of the single fiber.

[0123] Furthermore, relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the lubricant content in the fiber of this embodiment is preferably 12 parts by weight or less, more preferably 10 parts by weight or less, further preferably 8 parts by weight or less, and most preferably 5 parts by weight or less. By setting the lubricant content in the fiber of this embodiment to 12 parts by weight or less relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, it is advantageous to suppress the seepage of the lubricant onto the fiber surface.

[0124] The fiber fineness of the fiber in this embodiment is preferably 1 to 15 dtex, more preferably 2 to 13 dtex, and even more preferably 3 to 12 dtex.

[0125] By setting the fineness of the single fiber to 15 dtex or less, the fiber of this embodiment has the advantage of being usable for a variety of applications. For example, the fiber of this embodiment can be used as a material for making yarn.

[0126] By making the fineness of the above-mentioned single fiber 1 dtex or more, the fiber of this embodiment has the advantage of improved strength.

[0127] It should be noted that, in the case of multifilament fibers in this embodiment, the single fiber fineness refers to the average fineness of the single fibers contained in the fiber.

[0128] In this embodiment, when the fiber is a monofilament, the single fiber fineness refers to the fineness of the fiber itself.

[0129] The fineness of a single fiber can be determined by the method described in the examples below.

[0130] In this embodiment, when the fiber is a multifilament having multiple single fibers, it is preferable to have 30 or more single fibers, more preferably 30 to 300,000 single fibers, and even more preferably 50 to 300,000 single fibers.

[0131] From the viewpoint of excellent processability when processing fibers to obtain processed products, the weight-average molecular weight of the fibers in this embodiment is preferably 2.0 × 10⁻⁶. 5 ~6.0×10 5 More preferably 2.3×10 5 ~4.0×105 .

[0132] It should be noted that the weight-average molecular weight in this embodiment is the molecular weight determined by gel permeation chromatography (GPC) using chloroform eluent, and calculated from the molecular weight distribution of polystyrene. A suitable column for determining the above molecular weight can be used as the chromatographic column in this GPC.

[0133] For example, the weight-average molecular weight in this embodiment can be determined under the following conditions.

[0134] Measuring apparatus: Shimadzu 20A manufactured by Shimadzu Corporation

[0135] Column: Shodex K-806M manufactured by Showa Denko

[0136] Detector: RI detector

[0137] Standard material: polystyrene

[0138] Eluent: Chloroform (HPLC grade)

[0139] Flow rate: 1 mL / min

[0140] Temperature: 40℃

[0141] The fibers in this embodiment can be used directly in filament form.

[0142] Furthermore, by cutting the aforementioned fibers, short fibers with a length of less than 20 cm can be obtained. These short fibers can also be used directly as filaments.

[0143] Alternatively, the aforementioned fibers and / or short fibers can be used to make fiber products (fiber bodies).

[0144] This fiber product can be made into various shapes (e.g., non-woven fabric).

[0145] Fibers, staple fibers and fiber products can be suitably used for their previously known purposes.

[0146] Fibers, staple fibers and fiber products can be suitably used in fields such as agriculture (e.g., horticulture), fisheries, forestry, medical industry, and food industry.

[0147] In addition, examples of the aforementioned fiber products include: clothing, curtains, carpets, bags, shoes, wiping materials, hygiene products, automotive components, building materials, and filter materials (filters).

[0148] <Nonwoven fabric in this embodiment>

[0149] The nonwoven fabric of this embodiment contains the fibers of this embodiment.

[0150] Examples of nonwoven fabrics used in this embodiment include: thermally bonded nonwoven fabrics, needle-punched nonwoven fabrics, chemically bonded nonwoven fabrics, and air-laid nonwoven fabrics. Non-woven fabrics, wet-laid ( Non-woven fabrics, etc.

[0151] Regarding the fiber of this embodiment, since thermal bonding can be achieved at low temperatures when the fiber is thermally processed, it can be suitable for the production of thermally bonded nonwoven fabrics.

[0152] <Method for manufacturing fibers according to this embodiment>

[0153] The fiber manufacturing method of this embodiment obtains the above-mentioned fiber by melt spinning a core material composition and a sheath material composition using a core-sheath type composite spinning nozzle.

[0154] For example, the fiber manufacturing method of this embodiment includes: a spinning step in which a raw material composition is melted to obtain a melt by melt spinning, and the melt is spun to obtain an undrawn filament; and a drawing step in which the undrawn filament is drawn.

[0155] The above-mentioned raw material compositions respectively include a core raw material composition and a sheath raw material composition.

[0156] The above raw material composition contains a poly(3-hydroxyalkanoate) resin.

[0157] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition is preferably 3.0 × 10⁻⁶. 5 ~7.0×10 5 More 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 .

[0158] By making the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition 3.0 × 10⁻⁶ 5 The above methods can easily increase the weight-average molecular weight of poly(3-hydroxyalkanoate) resins in fibers, which in turn can easily increase the strength of fibers.

[0159] By making the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition 7.0 × 10⁻⁶ 5 The following steps facilitate fiber forming.

[0160] In the above spinning process, the core material composition is supplied to the core extruder, the sheath material composition is supplied to the sheath extruder, and the core material composition and the sheath material composition are melted to obtain the core melt and the sheath melt.

[0161] Then, the core melt and the sheath melt are extruded separately through a core-sheath type composite spinning nozzle and wound up by a winding roller to obtain one or more undrawn filaments.

[0162] In the above stretching process, one or more unstretched filaments are drawn from the winding roller section by the traction roller section, stretched in the stretching roller section, and wound in the heat treatment roller section, thereby obtaining fibers.

[0163] 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.

[0164] For example, in this embodiment, one or more unstretched filaments are stretched and then used as fibers. However, in this invention, one or more unstretched filaments can also be used as fibers.

[0165] [Public Projects]

[0166] The following items are disclosures of preferred embodiments.

[0167] [Project 1]

[0168] A fiber having a core-sheath structure comprising a core and a sheath, wherein,

[0169] The core and sheath portions respectively contain poly(3-hydroxyalkanoate) resins comprising 3-hydroxybutyrate units.

[0170] The average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core is greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath.

[0171] [Project 2]

[0172] According to the fiber described in Project 1, wherein,

[0173] The fiber comprises:

[0174] Copolymer (A), wherein the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units of monomers is 3-hydroxybutyrate units / other hydroxyalkanoate units = 99 / 1 to 93 / 7; and

[0175] The copolymer (B) has a monomer molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units of 92 / 8 to 76 / 24.

[0176] [Project 3]

[0177] According to the fiber described in Project 2, wherein,

[0178] The fiber contains 5 to 40% by weight of the copolymer (B) relative to 100% by weight of the poly(3-hydroxyalkanoate) resin.

[0179] [Project 4]

[0180] According to the fibers described in item 2 or 3, wherein,

[0181] The sheath contains the copolymer (B).

[0182] [Project 5]

[0183] According to the fiber described in Project 4, wherein

[0184] The sheath comprises the copolymer (A) and the copolymer (B).

[0185] [Project 6]

[0186] The fiber according to any one of items 1 to 5, wherein,

[0187] The area ratio of the core to the sheath in the cross-section of the fiber is core / sheath = 8 / 2 to 2 / 8.

[0188] [Project 7]

[0189] The fiber according to any one of items 1 to 6, wherein,

[0190] The poly(3-hydroxyalkanoate) resin is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0191] [Project 8]

[0192] The fiber according to any one of items 1 to 7, wherein,

[0193] The fineness of a single fiber is 1~15 dtex.

[0194] [Project 9]

[0195] A method for manufacturing a fiber, wherein the fiber described in any one of items 1 to 8 is obtained by melt spinning a core material composition and a sheath material composition by using a core-sheath type composite spinning nozzle.

[0196] [Project 10]

[0197] A nonwoven fabric comprising the fibers described in any one of items 1 to 8.

[0198] Example

[0199] The present invention will be further described in detail below with reference to embodiments and comparative examples. It should be noted that the present invention is not limited to these embodiments in any way.

[0200] The measurement and evaluation methods used in the examples and comparative examples are described below.

[0201] (Example 1)

[0202] First, the following materials were dry-mixed in the following proportions, and then melt-mixed at 150°C using an extruder to obtain granular core material compositions and sheath material compositions, respectively.

[0203] <Core Material Composition>

[0204] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 94.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 6 mol%, melting point: 145℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 582936) (P3HB3HH) (copolymer (A1)): 100 parts by weight

[0205] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0206] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0207] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0208] <Sheath Material Composition>

[0209] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 94.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 6 mol%, melting point: 145℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 582936) (P3HB3HH) (copolymer (A1)): 50 parts by mass

[0210] As a poly(3-hydroxyalkanoate) resin (copolymer (B)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 89.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 11.0 mol%, melting point: 108℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 582936) (P3HB3HH) (copolymer (B1)): 50 parts by mass

[0211] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0212] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0213] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0214] It should be noted that the molar content of 3-hydroxybutyrate units (3HB ratio), the molar content of 3-hydroxyhexanoate units (3HH ratio), and the weight-average molecular weight (Mw) were determined using the above method.

[0215] In the DSC curve obtained by differential scanning calorimetry (DSC), the melting point is set as the temperature at which the heat absorption is the greatest (the apex of the endothermic peak).

[0216] The differential scanning calorimetry (DSC) method described above is based on JIS K7122 (1987) "Method for determination of heat of conversion of plastics".

[0217] Specifically, the measurements were performed under the following conditions.

[0218] Apparatus: Seiko Instruments DSC6200 differential scanning calorimeter

[0219] Sample size: 4~10mg

[0220] Temperature range for measurement: 30℃~200℃

[0221] Heating rate: 10℃ / minute

[0222] The crystallization temperature (Tc) was determined according to JIS K7121-1987 "Method for determination of transformation temperature of plastics".

[0223] Specifically, using a differential scanning calorimeter (e.g., a DSC25 differential scanning calorimeter manufactured by TA Instruments), approximately 6.0 mg of the poly(3-hydroxyalkanoate) resin used as the sample was filled into the test container. Under the condition of nitrogen flow rate of 50 ml / min, the temperature was raised and cooled at a rate of 10 °C / min within the range of -30 °C to 180 °C. The peak temperature of the exothermic peak during the second cooling was set as the crystallization temperature.

[0224] When there are two or more exothermic peaks, the temperature of the peak top of the exothermic peak with the largest peak area is set as the crystallization temperature.

[0225] <Spinning Process>

[0226] Next, the granular core material composition is supplied to the core extruder, the granular sheath material composition is supplied to the sheath extruder, and the core material composition and the sheath material composition are melted to obtain the core melt and the sheath melt.

[0227] Next, using a concentric core-sheath type composite spinning nozzle (200 holes, 0.5mm diameter) set at 175℃, the core melt and sheath melt are extruded separately and wound onto the take-up roller at a speed of 250-300 m / min, resulting in 200 undrawn core-sheath composite fibers with a core-to-sheath area ratio (core:sheath) of 7:3 (hereinafter also referred to as the "core-sheath ratio").

[0228] <Core-Sheath Ratio>

[0229] It should be noted that, at room temperature, the fiber bundle was bundled and fixed with a shrink tube (total fineness 2200 dtex) to prevent it from shifting. Then, it was cut into circular slices with a cutter to create a fiber bundle for cross-sectional observation. The fiber bundle was photographed at 500x magnification using a laser microscope (Keyence Corporation, "VK-9500"), and the core-sheath ratio was determined based on the obtained fiber cross-sectional photographs.

[0230] <Stretching Process>

[0231] The 200 undrawn filaments obtained are drawn from the take-up roller section at the traction roller section (55.5 m / min, 30°C), drawn at the traction roller section (110 m / min, 90°C), and wound at the heat treatment roller section (100 m / min), thereby obtaining fibers (with 200 filaments as...) Figure 1 The cross-sectional shape of the core-sheath composite fiber shown is a single fiber multifilament (single fiber fineness 5.5 dtex, core-sheath ratio 7:3). The stretch ratio is set to 2.0 times, and the relaxation rate is set to 10%.

[0232] It should be noted that the traction roller section, stretching roller section, and heat treatment roller section each use roller sections consisting of two rollers with the same speed and the same temperature.

[0233] <Single Fiber Fineness>

[0234] It should be noted that the measurements were performed using an Auto Vibro type fineness measuring instrument, "DENIER COMPUTER type DC-11" (manufactured by Search Co., Ltd.), and the average value of the measured values ​​of 10 samples was calculated and used as the single fiber fineness.

[0235] (Example 2)

[0236] The core-sheath ratio of the undrawn yarn was set to 5:5. Otherwise, the same fiber (a multifilament with 200 single fibers as core-sheath composite fibers) was obtained as in Example 1 (single fiber fineness 6.1 dtex, core-sheath ratio 5:5).

[0237] (Example 3)

[0238] The raw material composition for the sheath was formulated in the following proportions, and otherwise, fibers (multifilaments having 200 single fibers as core-sheath composite fibers) (single fiber fineness 5.8 dtex) were obtained in the same manner as in Example 1.

[0239] As a poly(3-hydroxyalkanoate) resin (polymer (A)), the copolymer resin (3-hydroxybutyrate-co-3-hydroxyhexanoate) contains 30 parts by weight of (3-hydroxybutyrate unit content: 94.0 mol%, 3-hydroxyhexanoate content: 6 mol%, melting point: 145℃, crystallization temperature (Tc): 60℃, weight average molecular weight (Mw): 582936) (P3HB3HH) (polymer (A1)).

[0240] As a poly(3-hydroxyalkanoate) resin (copolymer (B)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (3-hydroxybutyrate unit content: 89.0 mol%, 3-hydroxyhexanoate content: 11.0 mol%, melting point: 108℃, crystallization temperature (Tc): 60℃, weight average molecular weight (Mw): 582936) (P3HB3HH) (copolymer (B1)): 70 parts by weight

[0241] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0242] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0243] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0244] (Example 4)

[0245] The single fiber fineness was set to 11.0 dtex, and otherwise, the same fiber (a multifilament having 200 single fibers as core-sheath composite fibers) was obtained as in Example 1.

[0246] (Example 5)

[0247] The core material composition was formulated in the following proportions, the sheath material composition was formulated in the following proportions, the core-sheath ratio of the undrawn yarn was set to 5:5, and no drawing process was performed. Otherwise, the same as in Example 1, fibers (multifilaments having 200 single fibers as core-sheath composite fibers) (single fiber fineness 4.5 dtex) were obtained.

[0248] <Core Material Composition>

[0249] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 97.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 3 mol%, melting point: 152℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 390000) (P3HB3HH) (copolymer (A2)): 100 parts by weight

[0250] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0251] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0252] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0253] <Sheath Material Composition>

[0254] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 94.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 6 mol%, melting point: 145℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 582936) (P3HB3HH) (copolymer (A1)): 50 parts by mass

[0255] As a poly(3-hydroxyalkanoate) resin (copolymer (B)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 89.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 11.0 mol%, melting point: 108℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 220000) (P3HB3HH) (copolymer (B2)): 50 parts by mass

[0256] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0257] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0258] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0259] (Example 6)

[0260] The core material composition was formulated in the following proportions, and the sheath material composition was formulated in the same proportions as in Example 5. The core-sheath ratio of the unstretched yarn was set to 5:5, and no stretching process was performed. Otherwise, the same as in Example 1, fibers (multifilaments having 200 single fibers as core-sheath composite fibers) (single fiber fineness 4.5 dtex) were obtained.

[0261] <Core Material Composition>

[0262] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 97.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 3 mol%, melting point: 152℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 390000) (P3HB3HH) (copolymer (A2)): 50 parts by mass

[0263] As a poly(3-hydroxyalkanoate) resin (copolymer (B)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (molar content of 3-hydroxybutyrate units (3HB ratio): 89.0 mol%, molar content of 3-hydroxyhexanoate units (3HH ratio): 11.0 mol%, melting point: 108℃, crystallization temperature (Tc): 60℃, weight-average molecular weight (Mw): 310000) (P3HB3HH) (copolymer (B3)): 5 parts by mass

[0264] Poly(3-hydroxybutyrate) (P3HB) (melting point: 180℃, crystallization temperature (Tc): 60℃, weight average molecular weight (Mw): 310000): 45 parts by weight, is a homopolymer of poly(3-hydroxyalkanoate) resin.

[0265] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0266] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0267] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0268] (Comparative Example 1)

[0269] The raw material composition for the sheath was formulated in the following proportions, and otherwise, fibers (multifilaments having 200 single fibers as core-sheath composite fibers) (single fiber fineness 5.6 dtex) were obtained in the same manner as in Example 1.

[0270] As a poly(3-hydroxyalkanoate) resin (copolymer (A)), the (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (3-hydroxybutyrate unit content: 94.0 mol%, 3-hydroxyhexanoate content: 6 mol%, melting point: 145℃, crystallization temperature (Tc): 60℃, weight average molecular weight (Mw): 582936) (P3HB3HH): 100 parts by weight

[0271] Erucamide (EA) as a lubricant containing amide bonds: 0.5 parts by weight

[0272] As a lubricant containing amide bonds, mountain Acid amide (BA): 0.5 parts by weight

[0273] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemicals Co., Ltd., Neulizer-P) as a nucleating agent for crystallization: 1.0 parts by weight

[0274] (Comparative Example 2)

[0275] Using only the core material composition of Example 1, but without using a concentric core-sheath type composite spinning nozzle, a single-layer spinning nozzle was used. Otherwise, fibers (multifilaments having 400 single fibers as single-layer fibers) (single fiber fineness 5.8 dtex) were obtained in the same manner as in Example 1.

[0276] (Comparative Example 3)

[0277] Using only the sheath material composition of Example 1, but without using a concentric core-sheath type composite spinning nozzle, a single-layer spinning nozzle was used. Otherwise, the same as in Example 1, fibers (multifilaments having 400 single fibers as single-layer fibers) (single fiber fineness 6.0 dtex) were obtained.

[0278] (Melt-to-stick ratio)

[0279] The melt viscosity is calculated as follows.

[0280] First, for multifilaments, which are fibers, all the single fibers contained in the fiber are cut off by cutting the fiber on a plane perpendicular to the length direction of the fiber.

[0281] Next, the cross-section of the multifilament was observed using a scanning electron microscope (SEM), and the total number of monofibrils contained in the cross-section and the number of monofibrils fused with other monofibrils in the cross-section were counted (also the number obtained by subtracting the number of monofibrils not fused with other monofibrils from the total number of monofibrils contained in the multifilament).

[0282] Next, the melt viscosity ratio was calculated using the following formula.

[0283] Melt bond rate (%) = (Number of monofibers fused with other monofibers in the cut surface / Total number of monofibers contained in the multifilament in the cut surface) × 100

[0284] (Heat fusion temperature)

[0285] Cut eight fibers from each fiber bundle at a rate of about 3 cm. Arrange four fibers in a grid pattern. Hold the bundle in an iron plate heated to 60-120°C and let it stand for 1 minute before removing it. The temperature at which the overlapping grid pattern fuses is taken as the heat fusion temperature.

[0286]

[0287] As shown in Table 1, among Examples 1 to 6 within the scope of the present invention, the heat-melting temperature was lower compared to Comparative Example 1 (only poly(3-hydroxyalkanoate) resin: copolymer (A)) with the same average molar content of 3-hydroxybutyrate units in the core and sheath, and Comparative Example 2 (only poly(3-hydroxyalkanoate) resin: copolymer (A)) with no core-sheath structure in the fiber.

[0288] Furthermore, in Examples 1 to 6 within the scope of the present invention, the melt-bonding ratio was low compared to Comparative Example 3 (poly(3-hydroxyalkanoate) resin: copolymer (A) and copolymer (B)) where the fiber did not have a core-sheath structure.

[0289] Therefore, according to the present invention, a fiber containing a poly(3-hydroxyalkanoate) resin can be provided, wherein melt bonding is suppressed during fiber manufacturing and thermal fusion can be achieved at low temperature during thermal processing of the fiber, wherein the fiber contains a poly(3-hydroxyalkanoate) resin comprising 3-hydroxybutyrate units.

Claims

1. A fiber having a core-sheath structure comprising a core and a sheath, wherein, The core and sheath portions respectively contain poly(3-hydroxyalkanoate) resins comprising 3-hydroxybutyrate units. The average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the core is greater than the average molar content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin of the sheath.

2. The fiber according to claim 1, wherein, The fiber comprises: Copolymer (A), wherein the molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units of monomers is 3-hydroxybutyrate units / other hydroxyalkanoate units = 99 / 1 to 93 / 7; and The copolymer (B) has a monomer molar ratio of 3-hydroxybutyrate units to other hydroxyalkanoate units of 92 / 8 to 76 / 24.

3. The fiber according to claim 2, wherein, The fiber contains 5 to 40% by weight of the copolymer (B) relative to 100% by weight of the poly(3-hydroxyalkanoate) resin.

4. The fiber according to claim 2 or 3, wherein, The sheath contains the copolymer (B).

5. The fiber according to claim 4, wherein, The sheath comprises the copolymer (A) and the copolymer (B).

6. The fiber according to any one of claims 1 to 3, wherein, The area ratio of the core to the sheath in the cross-section of the fiber is core / sheath = 8 / 2 to 2 / 8.

7. The fiber according to any one of claims 1 to 3, wherein, The poly(3-hydroxyalkanoate) resin is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

8. The fiber according to any one of claims 1 to 3, wherein, The fiber has a single fiber fineness of 1~15 dtex.

9. A method for manufacturing a fiber, wherein the fiber according to any one of claims 1 to 3 is obtained by melt spinning a core material composition and a sheath material composition by using a core-sheath type composite spinning nozzle.

10. A nonwoven fabric comprising the fibers according to any one of claims 1 to 3.

Images