Multifilament and method for producing same

Abstract

Provided are a method for producing a multifilament, and the like, with which it is possible to suppress breakage of a precursor and to suppress adhesion between monofilaments even if the average value of the fineness of the monofilaments is small. The present invention is a method for producing a multifilament in which a multifilament having a plurality of monofilaments is obtained by melt spinning using a spinning nozzle having a plurality of injection holes, the method comprising: a step (A) in which a raw material composition is heated and melted to obtain a melt, and the melt is ejected from the injection holes to obtain a plurality of raw filaments in a molten state; a step (B) for blowing a gas onto the plurality of filaments, the raw material composition containing a poly (3-hydroxyalkanoate) resin, the step (B) including: a step (B1) for cooling the plurality of filaments by blowing a first gas onto the plurality of filaments in a molten state; a step (B2) for blowing a second gas onto the plurality of strands cooled in the step (B1), the temperature of the first gas being (Tc-45 DEG C)-(Tc-30 DEG C) [Tc is the crystallization temperature of the poly (3-hydroxyalkanoate) resin] in the step (B1), and the temperature of the second gas being higher than the temperature of the first gas and being (Tc-30 DEG C)-(Tc-10 DEG C) in the step (B2); the average fineness of the monofilaments is 15 dtex or less.

Description

Technical Field

[0001] The present invention relates to multifilaments and a method for manufacturing the same. Background Art

[0002] In recent years, plastic waste has caused problems such as affecting the ecosystem, generating harmful gases when burned, and the large amount of combustion heat leading to global warming, which have become reasons for imposing a huge burden on the global environment. As a method for solving this problem, the development of biodegradable plastics has become increasingly popular.

[0003] Among such biodegradable plastics, the carbon dioxide generated when burning biodegradable plastics made from plant-derived raw materials already exists in the atmosphere, so the amount of carbon dioxide in the atmosphere does not increase. This is called carbon neutrality and is highly regarded in the case of the Kyoto Protocol that sets a carbon dioxide emission reduction target value, and its active use is expected.

[0004] Recently, from the viewpoints of biodegradability and carbon neutrality, aliphatic polyester resins, particularly polyhydroxyalkanoate resins, have attracted much attention as biodegradable plastics produced by microorganisms using plant-derived raw materials as a carbon source.

[0005] Among them, Patent Documents 1 to 3 disclose a method for manufacturing a multifilament having a plurality of monofilaments.

[0006] In addition, Patent Document 1 discloses that a multifilament having a plurality of monofilaments containing polyhydroxyalkanoate is obtained by a melt extrusion method.

[0007] Specifically, the manufacturing method described in Patent Document 1 includes: Step (A) of melting a raw material composition by heating and obtaining four raw filaments by ejecting the melted raw material composition from four nozzles; and Step (B) of obtaining the above-mentioned multifilament by stretching the four above-mentioned raw filaments.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: WO 2017 / 122679

[0011] Patent Document 2: WO 2021 / 206154

[0012] Patent Document 3: Japanese Patent Laid-Open No. 8-134718 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] Sometimes, it is required that the average fineness of the monofilaments in the multifilament is small.

[0015] The present inventors have conducted intensive research and found that when attempting to produce a multifilament with a small average fineness of monofilaments, the raw filaments break and it is impossible to produce a multifilament, or sometimes the monofilaments adhere to each other.

[0016] Therefore, the first object of the present invention is to provide a method for producing a multifilament that can suppress breakage of raw filaments and adhesion of monofilaments to each other even when the average fineness of the monofilaments is small. Another object of the present invention is to provide a multifilament having a small average fineness of monofilaments and suppressed adhesion of monofilaments to each other.

[0017] Means for Solving the Problems

[0018] A first aspect of the present invention relates to a method for producing a multifilament, which obtains a multifilament having a plurality of monofilaments by a melt spinning method using a spinneret having a plurality of orifices, the method comprising:

[0019] Step (A) of obtaining a melt by heating a raw material composition to melt it, and obtaining a plurality of raw filaments in a molten state by ejecting the melt from the orifices;

[0020] Step (B) of blowing a gas onto the plurality of raw filaments;

[0021] The raw material composition contains a poly(3-hydroxyalkanoate) resin,

[0022] The above step (B) includes: step (B1) of cooling the plurality of raw filaments in a molten state by blowing a first gas onto the plurality of raw filaments; step (B2) of blowing a second gas onto the plurality of raw filaments cooled in step (B1),

[0023] In the above step (B1), the temperature of the first gas is (Tc - 45°C) to (Tc - 30°C) [Tc: the crystallization temperature of the poly(3-hydroxyalkanoate) resin];

[0024] In the above step (B2), the temperature of the second gas is higher than the temperature of the first gas and is (Tc - 30°C) to (Tc - 10°C),

[0025] The average fineness of the monofilaments is 15 dtex or less.

[0026] A second aspect of the present invention relates to a multifilament having a plurality of monofilaments, wherein

[0027] The monofilaments contain a poly(3-hydroxyalkanoate) resin,

[0028] The average fineness of the monofilaments is 15 dtex or less,

[0029] The adhesion rate of the monofilaments is 10% or less.

[0030] Effects of the Invention

[0031] According to the first aspect of the present invention, even if the average fineness of the monofilaments is small, it is possible to suppress the breakage of the raw filaments and suppress the fusion adhesion between the monofilaments.

[0032] In addition, according to the second aspect of the present invention, it is possible to provide a multifilament in which the average fineness of the monofilaments is small and the fusion adhesion between the monofilaments is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic view of the apparatus used in steps (A) and (B) of the first embodiment.

[0034] Figure 2 It is a schematic view of the apparatus used in step (C) of the first embodiment.

[0035] Figure 3 It is a schematic view of the apparatus used in the second embodiment.

[0036] REFERENCE SIGNS

[0037] 100A: Raw filament

[0038] 101: Raw material input section

[0039] 102: Kneading extruder

[0040] 103: Gear pump

[0041] 104: Spinning nozzle

[0042] 105: First tank

[0043] 106: Second tank

[0044] 107: First drawing roll section

[0045] 108: First conveying roll section

[0046] 109: Second conveying roll section

[0047] 110: Third conveying roll section

[0048] 111: Fourth conveying roll section

[0049] 112: First winding roll section

[0050] 113: Second drawing roll section

[0051] 114: Stretching roll section

[0052] 115: Heat treatment roll section

[0053] 116: Second winding roll section

[0054] 207: Traction roll section

[0055] 208: First stretching roll section

[0056] 209: Second stretching roll section

[0057] 210: Third stretching roll section

[0058] 211: Take-off roll section

[0059] 212: Winding roll section Detailed implementation mode

[0060] Hereinafter, an implementation mode of the present invention will be described with reference to the accompanying drawings.

[0061] <<Manufacturing method of multifilament in this implementation mode>>

[0062] First, the manufacturing method of the multifilament in this implementation mode will be described.

[0063] The manufacturing method of the multifilament in this implementation mode is a method of obtaining a multifilament having multiple single filaments by the melt spinning method using a spinneret having a plurality of orifices.

[0064] In addition, the manufacturing method of the multifilament in this implementation mode includes: step (A), obtaining a melt by heating a raw material composition and ejecting the melt from the above-mentioned orifices to obtain a plurality of raw filaments in a molten state; step (B), blowing gas onto the plurality of above-mentioned raw filaments.

[0065] The above-mentioned raw material composition contains a poly(3-hydroxyalkanoate) resin.

[0066] The above-mentioned step (B) includes: step (B1), cooling the plurality of above-mentioned raw filaments in a molten state by blowing a first gas onto the plurality of above-mentioned raw filaments; step (B2), blowing a second gas onto the plurality of above-mentioned raw filaments cooled in step (B1).

[0067] In the above-mentioned step (B1), the temperature of the first gas is (Tc - 45°C) to (Tc - 30°C) [Tc: crystallization temperature of the above-mentioned poly(3-hydroxyalkanoate) resin].

[0068] In the above-mentioned step (B2), the temperature of the second gas is higher than the temperature of the first gas and is (Tc - 30°C) to (Tc - 10°C).

[0069] The average fineness of the above-mentioned single filaments is 15 dtex or less.

[0070] By setting the temperature of the above-described first gas to (Tc - 30°C) or lower, breakage of the precursor filaments can be suppressed.

[0071] By setting the temperature of the above-described first gas to (Tc - 30°C) or lower, the precursor filaments are sufficiently cooled. Therefore, it is considered that the time for the precursor filaments to become molten can be shortened, and the precursor filaments are less likely to break. In addition, it is considered that the time within the temperature range in which the poly(3-hydroxyalkanoate) - based resin constituting the precursor filaments is likely to crystallize can be shortened, and thus excessive crystallization of the poly(3-hydroxyalkanoate) - based resin can be suppressed. Also, it is considered that the flexibility of the precursor filaments is excellent (the elongational viscosity of the precursor filaments is low), and the precursor filaments are less likely to break when pulled by the drawing rollers described later.

[0072] In addition, by setting the temperature of the above-described first gas to (Tc - 45°C) or higher, adhesion between the monofilaments can be suppressed.

[0073] It is considered that by setting the temperature of the above-described first gas to (Tc - 45°C) or higher, the poly(3-hydroxyalkanoate) - based resin constituting the precursor filaments is likely to crystallize, and adhesion between the precursor filaments is suppressed. As a result, adhesion between the monofilaments is suppressed.

[0074] Furthermore, by setting the temperature of the above-described second gas to (Tc - 10°C) or lower, breakage of the precursor filaments can be suppressed.

[0075] By setting the temperature of the above-described first gas to (Tc - 10°C) or lower, it is considered that excessive crystallization of the poly(3-hydroxyalkanoate) - based resin constituting the precursor filaments can be suppressed. Also, it is considered that the softness of the precursor filaments is excellent (the elongational viscosity of the precursor filaments is low), and the precursor filaments are less likely to break when pulled by the drawing rollers described later.

[0076] In addition, by setting the temperature of the above-described second gas to (Tc - 30°C) or higher, adhesion between the monofilaments can be suppressed.

[0077] By setting the temperature of the above-described second gas to (Tc - 30°C) or higher, the poly(3-hydroxyalkanoate) - based resin constituting the precursor filaments is likely to crystallize, and adhesion between the precursor filaments is suppressed. As a result, it is considered that adhesion between the monofilaments is suppressed.

[0078] Therefore, according to the present embodiment, even if the average value of the fineness of the monofilaments is small, breakage of the precursor filaments can be suppressed and adhesion between the monofilaments can be suppressed.

[0079] In addition, the method for manufacturing a multifilament according to the present embodiment further includes step (C) after the above-described step (B): obtaining the above-described multifilament by stretching a plurality of the above-described precursor filaments.

[0080] The above-described raw material composition contains a polymer component and an additive.

[0081] The above polymer composition contains a poly(3-hydroxyalkanoate) resin.

[0082] In addition to the poly(3-hydroxyalkanoate) resin, the above polymer composition may also contain other polymers.

[0083] The above poly(3-hydroxyalkanoate) resin is a polyester with 3-hydroxyalkanoate as a monomer.

[0084] That is, the above poly(3-hydroxyalkanoate) resin is a resin containing 3-hydroxyalkanoate as a structural unit.

[0085] In addition, the above poly(3-hydroxyalkanoate) resin is a polymer with biodegradability.

[0086] It should be noted that the "biodegradability" in this embodiment refers to the property of being able to be decomposed into low-molecular compounds by microorganisms in nature. Specifically, the presence or absence of biodegradability can be judged by tests conforming to each environment 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. In addition, the degradability by microorganisms in seawater can be evaluated by measuring the biochemical oxygen demand.

[0087] The above poly(3-hydroxyalkanoate) resin contains a homopolymer and / or a copolymer.

[0088] The above poly(3-hydroxyalkanoate) resin preferably contains a structural unit represented by the following formula (1).

[0089] [-CHR-CH 2 -CO-O-](1)

[0090] (In the above formula (1), R represents an alkyl group represented by C p H 2p+1 , and p represents an integer from 1 to 15.)

[0091] The above poly(3-hydroxyalkanoate) resin preferably contains a resin with 3-hydroxybutyrate as a structural unit (poly(3-hydroxybutyrate) resin).

[0092] It should be noted that the poly(3-hydroxybutyrate) resin contains a homopolymer and / or a copolymer.

[0093] Examples of poly(3-hydroxyalkanoate) resins containing 3-hydroxybutyrate as a structural unit include, for example, P3HB, P3HB3HH, P3HB3HV, P3HB4HB, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), and the like.

[0094] Here, P3HB refers to poly(3-hydroxybutyrate) as a homopolymer.

[0095] P3HB3HH refers to poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0096] P3HB3HV refers to poly(3-hydroxybutyrate-co-3-hydroxypentanoate).

[0097] P3HB4HB refers to poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

[0098] 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 poly(3-hydroxyalkanoate) resins preferably contain P3HB.

[0099] As the above poly(3-hydroxyalkanoate) resins, from the viewpoint of achieving both excellent biodegradability and moldability, P3HB, P3HB3HH, P3HB3HV, P3HB4HB, etc. are preferred, and there is no particular limitation.

[0100] In addition, as the above poly(3-hydroxyalkanoate) resins, from the viewpoint of improving the strength of the multifilament of the present embodiment and improving moldability, P3HB3HH is preferred.

[0101] The above poly(3-hydroxyalkanoate) resins preferably contain 80 mol% or more of 3-hydroxybutyrate as a structural unit, more preferably 85.0 mol% to 99.5 mol%, and still more preferably 85.0 mol% to 97.0 mol%.

[0102] By making the above poly(3-hydroxyalkanoate) resins contain 80 mol% or more of 3-hydroxybutyrate as a structural unit, the rigidity of the multifilament increases.

[0103] In addition, by making the above poly(3-hydroxyalkanoate) resins contain 99.5 mol% or less of 3-hydroxybutyrate as a structural unit, the multifilament has excellent flexibility.

[0104] It should be noted that the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resins can be determined by the method described in the examples below.

[0105] The above polymer composition may contain only one of the above poly(3-hydroxyalkanoate) resins, or may contain two or more thereof.

[0106] When the above poly(3-hydroxyalkanoate) resin contains a copolymer (such as P3HB3HH), it may contain two or more copolymers having different average composition ratios of structural units.

[0107] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition is preferably 3.0×10 5 ~7.0×10 5 , more preferably 3.5×10 5 ~7.0×10 5 , further preferably 4.0×10 5 ~7.0×10 5 , most preferably 4.5×10 5 ~6.5×10 5 .

[0108] By making the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition 3.0×10 5 or more, it is easy to increase the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the monofilament, and thus it is easy to increase the strength of the multifilament.

[0109] By making the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition 7.0×10 5 or less, the formation of the multifilament becomes easy.

[0110] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition refers to the weight-average molecular weight of the poly(3-hydroxyalkanoate) resin in the above raw material composition before melting due to heating.

[0111] It should be noted that the weight-average molecular weight in this embodiment is measured using gel permeation chromatography (GPC) with chloroform eluent and based on the polystyrene-equivalent molecular weight distribution. As the chromatographic column for this GPC, an appropriate chromatographic column for measuring the above molecular weight can be used.

[0112] For example, the weight-average molecular weight in this embodiment can be measured under the following conditions.

[0113] Measuring device: Shimadzu 20A manufactured by Shimadzu Corporation

[0114] Chromatographic column: Shodex K-806M manufactured by Showa Denko KK

[0115] Detector: RI detector

[0116] Standard substance: Polystyrene

[0117] Eluent: Chloroform (HPLC grade)

[0118] Flow rate: 1 mL / min

[0119] Temperature: 40 °C

[0120] Other polymers preferably have biodegradability.

[0121] Examples of other biodegradable polymers include: polycaprolactone, polylactic acid, polybutylene succinate, polybutylene adipate succinate, polybutylene terephthalate adipate, polybutylene glycol succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, modified starch, cellulose acetate, chitosan, poly(4-hydroxyalkanoate) resins, etc.

[0122] The above polycaprolactone is a polymer formed by ring-opening polymerization of ε-caprolactone.

[0123] The above polymer component may contain one other polymer or may contain two or more.

[0124] The above polymer component preferably contains 50% by weight or more of poly(3-hydroxyalkanoate) resin, more preferably 80% by weight or more, and still more preferably 90% by weight or more.

[0125] By including a biodegradable polymer in the raw material composition, even if the multifilament is discarded in the environment, it is easily decomposed in the environment, so the burden on the environment can be suppressed.

[0126] Examples of the above additives include, for example, crystal nucleating agents, lubricants, plasticizers, spinning oils, stabilizers (antioxidants, ultraviolet absorbers, etc.), colorants (dyes, pigments, etc.), inorganic fillers, organic fillers, antistatic agents, etc.

[0127] In order to promote the crystallization of poly(3-hydroxyalkanoate) resin, the above raw material composition preferably contains a crystal nucleating agent.

[0128] The above crystal nucleating agent is a compound having the effect of promoting the crystallization of poly(3-hydroxyalkanoate) resin. In addition, the melting point of the above crystal nucleating agent is higher than that of poly(3-hydroxyalkanoate) resin.

[0129] Examples of the above-mentioned crystallization nucleating agents include inorganic substances (such as boron nitride, titanium oxide, talc, layered silicate, calcium carbonate, sodium chloride, and metal phosphates); sugar alcohol compounds of natural origin (such as pentaerythritol, erythritol, galactitol, mannitol, and arabinitol); polyvinyl alcohol; chitin; chitosan; polyethylene oxide; aliphatic carboxylates; aliphatic alcohols; aliphatic carboxylic acid esters; dicarboxylic acid derivatives (such as dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate); cyclic compounds having C=O and a functional group selected from NH, S, and O in the molecule (such as indigo, quinacridone, and quinacridone magenta); sorbitol derivatives (such as dibenzylidene sorbitol and bis(p-methylbenzylidene) sorbitol); compounds containing a nitrogen-containing heteroaromatic nucleus (such as pyridine ring, triazine ring, and imidazole ring) (such as pyridine, triazine, and imidazole); phosphate ester compounds; bisamides of higher fatty acids; metal salts of higher fatty acids; and branched poly(lactic acid), etc.

[0130] In addition, P3HB, which is a poly(3-hydroxyalkanoate)-based resin as described above, can also be used as a crystallization nucleating agent.

[0131] These can be used alone or in combination of two or more.

[0132] As the above-mentioned crystallization nucleating agent, from the viewpoints of the improvement effect of the crystallization rate of the poly(3-hydroxyalkanoate)-based resin and the compatibility and affinity with the poly(3-hydroxyalkanoate)-based resin, sugar alcohol compounds, polyvinyl alcohol, chitin, and chitosan are preferred.

[0133] In addition, among these sugar alcohol compounds, pentaerythritol is preferred.

[0134] The above-mentioned crystallization nucleating agent preferably has a crystalline structure at room temperature (25°C).

[0135] By making the above-mentioned crystallization nucleating agent have a crystalline structure at room temperature (25°C), it has the advantage of further promoting the crystallization of the poly(3-hydroxyalkanoate)-based resin.

[0136] In addition, the crystallization nucleating agent having a crystalline structure at room temperature (25°C) is preferably in powder form at room temperature (25°C).

[0137] Furthermore, the average particle size of the crystallization nucleating agent in powder form at room temperature (25°C) is preferably 10 μm or less.

[0138] With respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the content of the crystallization nucleating agent in the raw material composition is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and still more preferably 0.5 parts by weight or more. By making the content of the crystallization nucleating agent in the raw material composition 0.05 parts by weight or more with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, there is an advantage that the crystallization of the poly(3-hydroxyalkanoate) resin can be further promoted.

[0139] In addition, with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the content of the crystallization nucleating agent in the raw material composition is preferably 10 parts by weight or less, more preferably 8 parts by weight or less, and still more preferably 5 parts by weight or less. By making the content of the crystallization nucleating agent in the raw material composition 10 parts by weight or less with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the viscosity of the melt can be reduced when producing multifilaments from the melt, and as a result, there is an advantage that the production of multifilaments becomes easy.

[0140] It should be noted that since P3HB is a poly(3-hydroxyalkanoate) resin and can also function as a crystallization nucleating agent, when the raw material composition contains P3HB, the amount of P3HB is included both in the amount of the poly(3-hydroxyalkanoate) resin and in the amount of the crystallization nucleating agent.

[0141] The above raw material composition may also contain a lubricant.

[0142] Examples of the lubricant include lauric acid amide, myristic acid amide, stearic acid amide, behenic acid amide, and erucic acid amide.

[0143] With respect to 100 parts by weight of the above poly(3-hydroxyalkanoate) resin, the content of the lubricant in the raw material composition is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and still more preferably 0.5 parts by weight or more. By making the content of the lubricant in the raw material composition 0.05 parts by weight or more with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, there is an advantage that the lubricity of the monofilament is excellent.

[0144] In addition, with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, the content of the lubricant in the raw material composition is preferably 12 parts by weight or less, more preferably 10 parts by weight or less, still more preferably 8 parts by weight or less, and most preferably 5 parts by weight or less. By making the content of the lubricant in the raw material composition 12 parts by weight or less with respect to 100 parts by weight of the poly(3-hydroxyalkanoate) resin, there is an advantage that the exudation of the above lubricant to the surface of the multifilament can be suppressed.

[0145] <First Embodiment: Successive Stretching Method (Post-Stretching Method)>

[0146] Hereinafter, as an example, a method for manufacturing a multifilament by a successive stretching method (also referred to as a "post-stretching method") will be given, and reference will be made to Figure 1 , 2 the manufacturing method of the multifilament of the first embodiment will be described.

[0147] In the manufacturing method of the multifilament of the first embodiment, a plurality of the above-mentioned raw filaments are wound by a winding roll portion, and the plurality of the above-mentioned raw filaments wound by the winding roll portion are stretched.

[0148] (Process (A))

[0149] In the above process (A), first, a raw material composition is obtained by dry blending of materials, and the raw material composition is melt-kneaded by an extruder to obtain pellets.

[0150] Then, as Figure 1 shown, the pellets are put into the raw material input portion 101.

[0151] Next, the pellets input from the raw material input portion 101 are melted by heating using the kneading extruder 102 to obtain a melt as the melted raw material composition.

[0152] The above kneading extruder 102 is a screw extruder. The kneading extruder 102 may be a single-screw extruder or a twin-screw extruder.

[0153] Then, using a spinning nozzle 104 having a plurality of orifices, the melt obtained by the above kneading extruder 102 is ejected from the plurality of orifices, thereby obtaining a plurality of raw filaments 100A in a molten state.

[0154] It should be noted that the flow rate of the melt ejected from the plurality of orifices of the spinning nozzle 104 is adjusted by the gear pump 103.

[0155] The temperature of the above spinning nozzle 104 is, for example, 140 to 180 °C.

[0156] The above spinning nozzle 104 has a plurality of orifices, preferably 30 or more, more preferably 30 to 10000, and further preferably 30 to 5000.

[0157] The shape and size of each orifice can be selected according to the characteristics required for the multifilament (for example, appearance, fineness, strength, cross-sectional shape, etc.).

[0158] In the present embodiment, the shapes of the orifices are substantially the same as each other. In addition, the areas of the orifices are substantially the same as each other.

[0159] The area of each orifice is preferably 1.0×10 -3~20 mm 2 and more preferably 5.0 × 10 -3 ~10 mm 2 .

[0160] The speed at which the melt is ejected from the spinning nozzle 104 (hereinafter also referred to as "spinning nozzle flow rate") is preferably 0.02 m / min to 20 m / min, more preferably 0.05 m / min to 10 m / min, and further preferably 0.1 m / min to 5.0 m / min.

[0161] In the first embodiment, from the viewpoints of suppressing the adhesion of adjacent monofilaments to each other and suppressing the electrostatic repulsion between adjacent monofilaments, a spinning finish can be applied to the surfaces of each of the plurality of above-mentioned raw filaments 100A after cooling.

[0162] Examples of the above-mentioned spinning finish include: cationic surfactants, anionic surfactants, nonionic surfactants, refined esterified oils, mineral oils, poly(oxyethylene) alkyl ethers, silicone oils, paraffins, etc. These can be used alone or in combination of two or more.

[0163] From the viewpoint of suppressing the adhesion of adjacent monofilaments to each other, the above-mentioned spinning finish is preferably a silicone oil.

[0164] From the viewpoint of suppressing the electrostatic repulsion between adjacent monofilaments, the above-mentioned spinning finish is preferably an anionic surfactant or a nonionic surfactant.

[0165] As the above-mentioned spinning finish, for example, a spinning finish containing a silicone oil and an anionic surfactant (for example, "Polymax FKY" manufactured by Marubishi Oil Co., Ltd.) can be used.

[0166] (Process (B))

[0167] In the above-mentioned process (B), a gas is blown onto the plurality of above-mentioned raw filaments 100A.

[0168] Examples of the above-mentioned gas include air, inert gases (nitrogen, argon, etc.), water vapor, etc.

[0169] In the above-mentioned process (B), a gas is blown onto the plurality of above-mentioned raw filaments 100A in a box.

[0170] Examples of the blowing method include the circular method, the backside method, etc.

[0171] The above-mentioned backside method is a method of blowing the above-mentioned gas onto the plurality of above-mentioned raw filaments from one direction in a box as observed from the longitudinal direction of the raw filaments (observed from the cross-section of the raw filaments perpendicular to the longitudinal direction of the raw filaments).

[0172] The above-described circulation method is a method of using a box having a cylindrical side wall, blowing a gas spirally along the inner circumferential surface of the cylindrical side wall into the cylindrical box, and blowing the gas onto a plurality of the above-described raw filaments. It should be noted that the flow direction of the raw filaments is substantially parallel to the imaginary axis of the cylindrical side wall.

[0173] The above-described box has a cylindrical perforated metal plate inside the cylindrical side wall. In addition, a cylindrical net (for example, 80 mesh) may be provided inside the cylindrical perforated metal plate. The outer diameter of the cylindrical perforated metal plate is smaller than the inner diameter of the cylindrical side wall. The outer diameter of the cylindrical net is smaller than the inner diameter of the cylindrical perforated metal plate.

[0174] At this time, in the above-described circulation method, a plurality of the above-described raw filaments pass through the inside of the cylindrical net.

[0175] As the blowing method, the above-described circulation method is preferred. The above-described circulation method can blow the gas onto a plurality of the above-described raw filaments relatively uniformly. As a result, the deviation of the fineness of the raw filaments can be suppressed.

[0176] In the above-described step (B), it is preferred to discharge the gas in contact with the above-described raw filaments to the outside of the box along the flow direction of the raw filaments. In order to discharge the gas in contact with the above-described raw filaments to the outside of the box along the flow direction of the raw filaments, for example, a rectifying plate, rectifying fins, an ejector, a Venturi tube, Transvector manufactured by Koei Corporation, etc. can be used.

[0177] The above-described step (B) includes: step (B1) of cooling a plurality of the above-described raw filaments 100A by blowing a first gas onto the plurality of the above-described raw filaments 100A in a molten state; and step (B2) of blowing a second gas onto the plurality of the cooled raw filaments 100A.

[0178] In the above-described step (B1), a plurality of the above-described raw filaments 100A are cooled by blowing a first gas onto the plurality of the above-described raw filaments 100A in a molten state in a first box 105.

[0179] In the above-described step (B1), the temperature of the above-described first gas is set to (Tc - 45°C) to (Tc - 30°C) [Tc: the crystallization temperature of the above-described poly(3-hydroxyalkanoate) resin], preferably set to (Tc - 40°C) to (Tc - 30°C), and more preferably set to (Tc - 38°C) to (Tc - 33°C).

[0180] It should be noted that the crystallization temperature (Tc) of the above-described poly(3-hydroxyalkanoate) resin can be measured in accordance with JIS K7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0181] Specifically, using a differential scanning calorimeter (for example, DSC25 differential scanning calorimeter manufactured by TA Instruments), about 6.0 mg of a poly(3-hydroxyalkanoate) resin as a sample was filled into a measurement container, and under the condition of a nitrogen flow rate of 50 ml / min, the temperature was raised and cooled at a rate of 10 °C / min in the range of -30 °C to 180 °C, and the peak temperature of the exothermic peak during the second cooling was taken as the crystallization temperature.

[0182] In the case where there are two or more exothermic peaks, the peak temperature of the exothermic peak with the largest peak area is taken as the crystallization temperature.

[0183] In addition, the temperature of the gas in step (B1) and step (B2) of the present embodiment refers to the temperature of the gas when it contacts the raw filament 100A.

[0184] In the above step (B1), it is preferable to set the velocity of the first gas to 0.1 to 1.0 m / s, more preferably 0.15 to 0.6 m / s, and further preferably 0.17 to 0.3 m / s.

[0185] By making the velocity of the first gas 0.1 m / s or more, the raw filament 100A can be sufficiently cooled by the first gas. Therefore, breakage of the raw filament 100A can be further suppressed.

[0186] By making the velocity of the first gas 1.0 m / s or less, shaking of the raw filament 100A in the first gas can be suppressed.

[0187] Therefore, breakage of the raw filament 100A caused by shaking can be suppressed.

[0188] In addition, adhesion due to collision of the raw filaments 100A caused by shaking can also be suppressed. As a result, adhesion between monofilaments can be further suppressed.

[0189] The distance between the orifice of the spinning nozzle 104 and the position where the raw filament 100A ejected from the orifice contacts the gas in the above step (B1) is determined according to the required characteristics of the multifilament, and generally a shorter distance is preferred.

[0190] As the blowing method in the above step (B1), from the viewpoint of suppressing the deviation of the fineness of the raw filament 100A, the above circulation method is preferred.

[0191] In the above step (B2), the second gas is blown onto the cooled multiple raw filaments 100A in the second box 106.

[0192] In the above step (B2), the temperature of the second gas is set to be higher than the temperature of the first gas.

[0193] In addition, in the above-mentioned step (B2), the temperature of the above-mentioned second gas is set to (Tc - 30°C) to (Tc - 10°C), preferably (Tc - 27°C) to (Tc - 15°C).

[0194] In the above-mentioned step (B2), it is preferable to set the velocity of the above-mentioned second gas to 0.005 to 1.5 m / s, more preferably 0.05 to 1.0 m / s, and further preferably 0.10 to 0.5 m / s.

[0195] By setting the velocity of the above-mentioned second gas to 0.005 m / s or more, the fusion adhesion between monofilaments can be further suppressed.

[0196] By setting the velocity of the above-mentioned second gas to 0.005 m / s or more, it is easy to crystallize the poly(3-hydroxyalkanoate)-based resin constituting the raw filament 100A, and the fusion adhesion between the raw filaments 100A is suppressed. As a result, it is considered that the fusion adhesion between monofilaments is suppressed.

[0197] In addition, by setting the velocity of the above-mentioned second gas to 1.5 m / s or less, the raw filament 100A can be suppressed from shaking in the second gas.

[0198] Moreover, the breakage of the raw filament 100A caused by shaking can be suppressed.

[0199] In addition, the fusion adhesion caused by the collision between the raw filaments 100A due to shaking can be suppressed. As a result, the fusion adhesion between monofilaments can be further suppressed.

[0200] In the above-mentioned step (B2), it is preferable to heat the plurality of the above-mentioned raw filaments 100A by blowing the second gas onto the plurality of the above-mentioned raw filaments 100A cooled in the step (B1).

[0201] In the above-mentioned step (B2), compared with the case of the plurality of the above-mentioned raw filaments 100A cooled in the above-mentioned step (B2), by blowing the second gas onto the plurality of the above-mentioned raw filaments 100A cooled in the step (B1) to heat the plurality of the above-mentioned raw filaments 100A, the temperature of the plurality of the above-mentioned raw filaments 100A can be easily adjusted. As a result, it is easier to crystallize the plurality of the above-mentioned raw filaments 100A.

[0202] In the above-mentioned step (B2), the temperature of the above-mentioned second gas is set to be higher than the temperature of the first gas.

[0203] The value obtained by subtracting the temperature of the above-mentioned first gas from the temperature of the above-mentioned second gas is preferably 5 to 25°C, more preferably 7 to 23°C, and further preferably 9 to 20°C.

[0204] In the above-mentioned step (B) of the first embodiment, after the above-mentioned step (B2), a plurality of the above-mentioned raw filaments 100A are drawn by the first drawing roller unit 107.

[0205] The above-mentioned first drawing roller unit 107 is composed of two rollers. It should be noted that the first drawing roller unit 107 may be composed of one roller or may be composed of three or more rollers.

[0206] Moreover, in the above-mentioned step (B), a plurality of the above-mentioned raw filaments 100A drawn by the first drawing roller unit 107 are wound up by the first winding roller unit 112.

[0207] In the first embodiment, the first conveying roller unit 108, the second conveying roller unit 109, the third conveying roller unit 110, and the fourth conveying roller unit 111 are used to convey a plurality of the above-mentioned raw filaments 100A drawn by the above-mentioned first drawing roller unit 107 to the above-mentioned first winding roller unit 112.

[0208] In Figure 1 each of the conveying roller units is composed of two rollers, and may also be composed of one roller or may be composed of three or more rollers.

[0209] In order to stretch the raw filaments in the above-mentioned step (C), it is preferable that substantially no stretching of a plurality of the above-mentioned raw filaments 100A is performed in the above-mentioned step (B), or substantially no stretching of a plurality of the above-mentioned raw filaments 100A is performed.

[0210] That is, the draw ratio in the above-mentioned step (B) is preferably 1.5 times or less, more preferably 1.2 times or less, and still more preferably 1.05 times or less.

[0211] The draw ratio in the above-mentioned step (B) can be obtained by the following formula.

[0212] The draw ratio in the above-mentioned step (B) = the speed of the conveying roller unit (m / min) / the speed of the drawing roller unit used in the above-mentioned step (B) (in the first embodiment, it is the "first drawing roller unit 107") (m / min)

[0213] It should be noted that the speed (m / min) of the drawing roller unit used in the above-mentioned step (B) is the length per unit time of a plurality of the above-mentioned raw filaments 100A drawn by the drawing roller unit used in the above-mentioned step (B) (in the first embodiment, it is the "first drawing roller unit 107").

[0214] The speed of the above-mentioned conveying roller unit is the length per unit time of a plurality of the above-mentioned raw filaments 100A conveyed by the conveying roller unit.

[0215] In the case of using a plurality of conveying roller units, the highest speed among the plurality is set as the "speed of the conveying roller unit".

[0216] In the case of not using the conveying roller part, the draw ratio in the above-mentioned step (B) is set to 1.0 times.

[0217] It should be noted that, in Figure 1 in the above-mentioned step (B), multiple of the above-mentioned raw filaments 100A are wound by the first winding roller part 112. However, in the first embodiment, multiple of the above-mentioned raw filaments 100A may not be wound by the first winding roller part 112, but may be accommodated in a containing container to obtain raw filaments.

[0218] (Step (C))

[0219] As Figure 2 shown, in the above-mentioned step (C), multiple of the above-mentioned raw filaments 100A are heated and drawn.

[0220] In the above-mentioned step (C), multiple of the above-mentioned raw filaments 100A are drawn from the above-mentioned first winding roller part 112 by the second drawing roller part 113.

[0221] Next, in the above-mentioned step (C), multiple of the above-mentioned raw filaments 100A drawn by the second drawing roller part 113 are drawn by the drawing roller part 114.

[0222] And, in the above-mentioned step (C), multiple of the above-mentioned raw filaments 100A drawn by the drawing roller part 114 are wound by the second winding roller part 116 to obtain multifilaments.

[0223] In addition, in the above-mentioned step (C), while heating multiple of the above-mentioned raw filaments 100A stretched by the above-mentioned drawing roller part 114 by the heat treatment roller part 115, conveyance can be performed.

[0224] The above-mentioned second drawing roller part 113 is composed of 2 rollers. It should be noted that the second drawing roller part 113 may be composed of 1 roller or may be composed of 3 or more rollers.

[0225] In the above-mentioned step (C), it is preferable to heat multiple of the above-mentioned raw filaments 100A by the above-mentioned second drawing roller part 113.

[0226] In the above-mentioned step (C), by heating multiple of the above-mentioned raw filaments 100A by the above-mentioned second drawing roller part 113, it is easy to adjust the temperature of multiple of the above-mentioned raw filaments 100A so that it is within a temperature range suitable for improving the orientation of the polymer component contained in multiple of the above-mentioned raw filaments 100A. As a result, it is easy to improve the orientation of the polymer component of multiple of the above-mentioned raw filaments 100A.

[0227] The temperature of the above-mentioned second drawing roller part 113 is preferably 15°C or higher and lower than 60°C, more preferably 15 - 55°C, and further preferably 15 - 30°C.

[0228] It should be noted that when the temperature of the environment for performing the above-mentioned step (C) is 15°C or higher, the above-mentioned second take-up roller section 113 may not be used to heat the multiple raw filaments 100A.

[0229] The above-mentioned stretching roller section 114 is composed of two rollers. It should be noted that the stretching roller section 114 may be composed of one roller or may be composed of three or more rollers.

[0230] In the above-mentioned step (C), the multiple raw filaments 100A may not be heated by the above-mentioned stretching roller section 114.

[0231] In the above-mentioned step (C), by heating the multiple raw filaments 100A with the above-mentioned stretching roller section 114, the crystallization of the polymer component contained in the multiple raw filaments 100A can be promoted, or the heat resistance of the polymer component can be improved.

[0232] The temperature of the above-mentioned stretching roller section 114 is preferably 30 to 100°C, more preferably 40 to 90°C.

[0233] The above-mentioned heat treatment roller 115 is composed of two rollers. It should be noted that the above-mentioned heat treatment roller 115 may be composed of one roller or may be composed of three or more rollers.

[0234] In the above-mentioned step (C), by heating the multiple raw filaments 100A with the above-mentioned heat treatment roller 115, the crystallization of the polymer component contained in the multiple raw filaments 100A can be promoted, or the heat resistance of the polymer component contained in the first single filament can be improved.

[0235] The temperature of the above-mentioned heat treatment roller 115 is preferably 60 to 110°C, more preferably 80 to 100°C.

[0236] It should be noted that in the step (C) of the first embodiment, the multiple raw filaments 100A are heated by the take-up roller section 113, the stretching roller section 114, and the heat treatment roller section 115. However, in order to control the orientation, crystallization, and heat resistance of the polymer component of the multiple raw filaments 100A, the multiple raw filaments 100A may be appropriately heated.

[0237] For example, the multiple raw filaments 100A may be heated by the raw filament take-up roller section 112.

[0238] In addition, multiple raw filaments 100A may be heated by the second take-up roller section 116 to obtain multifilaments.

[0239] Multiple of the above-mentioned raw filaments 100A can be heated by all the rollers from the raw-filament take-up roller section 112 to the second take-up roller section 116. Alternatively, multiple of the above-mentioned raw filaments 100A can be heated by only a part of all the rollers from the raw-filament take-up roller section 112 to the second take-up roller section 116, and not by the other rollers.

[0240] It should be noted that the control of heating multiple of the above-mentioned raw filaments 100A by the rollers is preferably carried out separately for each roller section.

[0241] In addition, the method of heating the polymer component of multiple of the above-mentioned raw filaments 100A in the process (C) of the first embodiment (hereinafter, also simply referred to as "heating method") can be a method of heating the polymer component of multiple of the above-mentioned raw filaments 100A by heating the rollers of the roller section.

[0242] In addition, the roller section has a container for accommodating the roller and a liquid (such as water) accommodated in the container together with the roller, and the above-mentioned heating method can be a method of heating the polymer component of multiple of the above-mentioned raw filaments 100A by heating the liquid. In the above-mentioned process (C), for example, stretching in a bath can be carried out.

[0243] In addition, the above-mentioned heating method can be a method of heating the polymer component of multiple of the above-mentioned raw filaments 100A by blowing heated gas (such as air, etc.) near the above-mentioned roller section or the above-mentioned roller.

[0244] In addition, these heating methods can be used in combination.

[0245] The draw ratio in the above-mentioned process (C) is 1.5 times or more, preferably 1.7 times or more. The draw ratio in the above-mentioned process (C) is, for example, 3.0 times or less.

[0246] By making the draw ratio in the above-mentioned process (C) 1.5 times or more, the orientation of the polymer component of multiple of the above-mentioned raw filaments 100A becomes further higher.

[0247] The draw ratio in the above-mentioned process (C) can be obtained by the following formula.

[0248] The draw ratio in the above-mentioned process (C) = the speed of the stretching roller section (m / min) / the speed (m / min) of the take-up roller section used in the above-mentioned process (C) (the "second take-up roller section 113" in the first embodiment)

[0249] In the above-mentioned process (C), the relaxation rate obtained by the following formula is preferably 1 to 15%.

[0250] Relaxation ratio (%) = ((speed of the above-mentioned stretching roller section 114 - speed of the winding roller section for winding multiple above-mentioned raw filaments stretched by the above-mentioned stretching roller section (in the first embodiment, it is the "second winding roller section 116")) / speed of the winding roller section for winding multiple above-mentioned raw filaments stretched by the above-mentioned stretching roller section) × 100

[0251] It should be noted that the speed (m / min) of the above-mentioned stretching roller section is the length per unit time of the stretching multifilament transported by the stretching roller section.

[0252] In the first embodiment, only one stretching roller section is used, and multiple stretching roller sections can also be used. In the case of using multiple stretching roller sections, the highest speed among them is set as the "speed of the stretching roller section".

[0253] The speed (m / min) of the drawing roller section used in the above-mentioned process (C) is the length per unit time of the stretching multifilament transported by the drawing roller section.

[0254] The speed (m / min) of the winding roller section for winding multiple above-mentioned raw filaments stretched by the above-mentioned stretching roller section is the length per unit time of the multiple above-mentioned raw filaments wound by the winding roller section.

[0255] <Second Embodiment: Rotational Drawing Method>

[0256] Next, refer to Figure 3 to describe the second embodiment.

[0257] It should be noted that the description repeated with the first embodiment is omitted, and the content not specifically described in the second embodiment is the same as that described in the first embodiment.

[0258] The method for manufacturing the multifilament in the second embodiment is a method for manufacturing a multifilament by the rotational drawing method.

[0259] The rotational drawing method is a method for implementing the following processes in one step: from the process of obtaining multiple molten raw filaments by ejecting a melt from multiple nozzles to the process of stretching the multiple above-mentioned raw filaments using a stretching roller section. The rotational drawing method is also called the "SDY method" or the "direct spinning and drawing method".

[0260] In the above-mentioned process (C) of the second embodiment, as Figure 3 shown, after process (B2), multiple above-mentioned raw filaments 100A are drawn using a drawing roller section 207.

[0261] Next, the multiple above-mentioned raw filaments 100A drawn using the drawing roller section 207 are stretched using three stretching roller sections (the first stretching roller section 208, the second stretching roller section 209, and the third stretching roller section 210).

[0262] Then, in the above step (C), the winding roller unit 212 winds multiple of the above-mentioned raw filaments 100A that have been drawn by the above-mentioned drawing roller unit to obtain a multifilament.

[0263] In addition, in the above step (C), the multiple raw filaments that have been drawn by the above-mentioned drawing roller unit can be transported by the payout roller unit 211.

[0264] The take-up roller unit 207 is Figure 3 constituted by two rollers, but it can be constituted by one roller or can be constituted by three or more rollers.

[0265] Each of the drawing roller units 208, 209, and 210 is Figure 3 constituted by two rollers, but it can be constituted by one roller or can be constituted by three or more rollers.

[0266] From the viewpoints of promoting the crystallization of the polymer component contained in the multiple raw filaments 100A or improving the heat resistance of the polymer component contained in the multiple raw filaments 100A, the temperature of each of the drawing roller units 208, 209, and 210 is preferably 30 to 100 °C, more preferably 40 to 90 °C.

[0267] In the present embodiment, the value of the spinning draw ratio (NDR) is preferably 50 or more, more preferably 80 or more. In addition, NDR is usually 5000 or less.

[0268] NDR can be obtained by the following formula.

[0269] NDR = the speed (m / min) of the take-up roller unit (the first take-up roller unit) that initially draws the raw filaments from the spinning nozzle / the flow rate (m / min) of the spinning nozzle

[0270] By making NDR 50 or more, the orientation of the polymer component contained in the multiple raw filaments 100A can be improved, and thus the strength of the multifilament can be further increased.

[0271] It should be noted that in the first embodiment (successive drawing method), the first take-up roller unit that initially draws the multiple raw filaments 100A is the first take-up roller unit 107.

[0272] In addition, in the second embodiment (rotary wire drawing method), the first take-up roller unit that initially draws the multiple raw filaments 100A is the take-up roller unit 207.

[0273] <<Multifilament of the Present Embodiment>>

[0274] Next, the multifilament of the present embodiment will be described.

[0275] The multifilament of the present embodiment has multiple single filaments.

[0276] The above-mentioned monofilament contains a poly(3-hydroxyalkanoate) resin.

[0277] The average fineness of the above-mentioned monofilament is 15 dtex or less.

[0278] The melt adhesion rate of the above-mentioned monofilament is 10% or less.

[0279] The above-mentioned monofilament is formed from a resin composition.

[0280] The above-mentioned resin composition contains a polymer component and an additive.

[0281] The above-mentioned polymer component contains a poly(3-hydroxyalkanoate) resin.

[0282] In addition, in addition to the poly(3-hydroxyalkanoate) resin, the above-mentioned polymer component may also contain the above-mentioned other polymers.

[0283] As the above-mentioned additive, an additive exemplified as an additive of the above-mentioned raw material composition can be exemplified.

[0284] The above-mentioned multifilament can be produced by the production method of the above-mentioned multifilament.

[0285] From the viewpoint of excellent processability when obtaining a processed product from the processed multifilament, the weight-average molecular weight of the above-mentioned resin composition is preferably 2.0×10 5 ~6.0×10 5 、more preferably 2.3×10 5 ~4.0×10 5 .

[0286] In addition, the above-mentioned multifilament preferably has 30 or more monofilaments, more preferably 30 to 300,000 monofilaments, and still more preferably 50 to 300,000 monofilaments.

[0287] The average fineness of the above-mentioned monofilament is 15 dtex or less. Based on this, the multifilament can be used for various purposes. For example, the multifilament can be used as a material for making spun yarns.

[0288] The average fineness of the above-mentioned monofilament is preferably 0.5 dtex or more, more preferably 1.0 dtex or more.

[0289] The average fineness of the above-mentioned monofilament is preferably 10 dtex or less, more preferably 7.0 dtex or less.

[0290] In the present embodiment, the average fineness of the monofilament can be obtained as follows.

[0291] First, measure the fineness (total fineness) of the multifilament. In addition, find the number of monofilaments contained in the multifilament.

[0292] Then, the average fineness of the monofilaments is obtained by the following formula.

[0293] Average fineness of monofilaments = Fineness of multifilament / Number of monofilaments contained in the multifilament

[0294] The melt adhesion rate of the above-mentioned monofilaments is 10% or less, preferably 7% or less, more preferably 5% or less, and further preferably 3% or less.

[0295] By making the melt adhesion rate of the monofilaments 10% or less, it is easier to exhibit the advantages brought by the average fineness of the monofilaments being 15 dtex or less and the monofilaments being fine. In addition, by making the melt adhesion rate of the monofilaments 10% or less, the processability is excellent when processing the multifilament to obtain a processed product. Furthermore, by making the melt adhesion rate of the monofilaments 10% or less, for example, when manufacturing staple fibers by cutting the multifilament, the staple fibers can be manufactured with a high yield.

[0296] The smaller the melt adhesion rate of the above-mentioned monofilaments, the more preferable, and it can be 0.00%, for example.

[0297] The melt adhesion rate of the above-mentioned monofilaments can be obtained as described below.

[0298] First, for the multifilament, all the monofilaments contained in the multifilament are cut by cutting the multifilament with a plane perpendicular to the length direction of the multifilament.

[0299] Next, the cut surface of the multifilament is observed using a scanning electron microscope (SEM), and the total number of monofilaments contained in the multifilament in the cut surface and the number of monofilaments fused to other monofilaments in the cut surface (which is also "the number obtained by subtracting 'the number of monofilaments not fused to other monofilaments' from 'the total number of monofilaments contained in the multifilament'") are counted.

[0300] Then, the melt adhesion rate is obtained by the following formula.

[0301] Melt adhesion rate (%) = (Number of monofilaments fused to other monofilaments in the cut surface / Total number of monofilaments contained in the multifilament in the cut surface) × 100

[0302] The maximum height roughness of the above-mentioned monofilaments is preferably 0.10 - 0.50 μm, more preferably 0.12 - 0.42 μm, and further preferably 0.15 - 0.40 μm.

[0303] By making the maximum height roughness of the above-mentioned monofilaments 0.10 μm or more, there is an advantage of suppressing the adhesion of monofilaments to each other.

[0304] By making the maximum height roughness of the above-mentioned monofilaments 0.50 μm or less, it is possible to suppress the monofilaments from being caught by the processing device, etc. when processing the multifilament to obtain a processed product, and there is an advantage of excellent processability.

[0305] The maximum height roughness of the above-mentioned monofilament can be obtained by the method described in the following examples.

[0306] The above-mentioned multifilament can be used directly in a linear form.

[0307] In addition, by cutting the multifilament, short fibers with a length of 20 cm or less can be obtained. In addition, the short fibers can be used directly in a linear form.

[0308] In addition, fiber products (fiber bodies) can be made using the above-mentioned multifilaments and / or short fibers.

[0309] The fiber products can be made into various shapes (for example, non-woven fabric shape, etc.).

[0310] The multifilament, short fibers, and fiber products can be suitably used for conventionally well-known uses.

[0311] The multifilament, short fibers, and fiber products can be suitably used in, for example, fields such as agriculture (for example, horticulture, etc.), fishery, forestry, medical industry, food industry, etc.

[0312] In addition, examples of the above-mentioned fiber products include clothing, curtains, carpets, leather bags, shoes, wiping materials, sanitary products, automotive parts, building materials, filter materials (filters), etc.

[0313] 〔Disclosed items〕

[0314] The following items are respectively disclosures of preferred embodiments.

[0315] 〔Item 1〕

[0316] A method for manufacturing a multifilament, which obtains a multifilament having multiple monofilaments by a melt spinning method using a spinneret having multiple orifices, the method comprising:

[0317] Step (A), melting the raw material composition by heating to obtain a melt, and ejecting the melt from the orifices to obtain multiple molten filaments;

[0318] Step (B), blowing gas onto the multiple filaments;

[0319] The raw material composition contains a poly(3-hydroxyalkanoate) - based resin,

[0320] The step (B) includes: step (B1), cooling the multiple molten filaments by blowing a first gas onto the multiple molten filaments; step (B2), blowing a second gas onto the multiple filaments cooled in the step (B1),

[0321] In the step (B1), the temperature of the first gas is set to (Tc - 45°C) to (Tc - 30°C) [Tc: crystallization temperature of the poly(3-hydroxyalkanoate) resin].

[0322] In the step (B2), the temperature of the second gas is set to be higher than the temperature of the first gas and is set to (Tc - 30°C) to (Tc - 10°C).

[0323] The average fineness of the monofilaments is 15 dtex or less.

[0324] 〔Item 2〕

[0325] The method for manufacturing a multifilament according to Item 1, wherein

[0326] In the step (B1), the temperature of the first gas is set to (Tc - 40°C) to (Tc - 30°C).

[0327] 〔Item 3〕

[0328] The method for manufacturing a multifilament according to Item 1 or 2, wherein

[0329] In the step (B1), the velocity of the first gas is set to 0.1 to 1.0 m / s.

[0330] 〔Item 4〕

[0331] The method for manufacturing a multifilament according to any one of Items 1 to 3, wherein

[0332] In the step (B2), the velocity of the second gas is set to 0.005 to 1.5 m / s.

[0333] 〔Item 5〕

[0334] The method for manufacturing a multifilament according to any one of Items 1 to 4, wherein

[0335] The value obtained by subtracting the temperature of the first gas from the temperature of the second gas is set to 5 to 25°C.

[0336] 〔Item 6〕

[0337] The method for manufacturing a multifilament according to any one of Items 1 to 5, wherein

[0338] The poly(3-hydroxyalkanoate) resin contains a poly(3-hydroxybutyrate) resin.

[0339] 〔Item 7〕

[0340] A multifilament having a plurality of monofilaments, wherein

[0341] The monofilament contains a poly(3-hydroxyalkanoate) resin,

[0342] The average fineness of the monofilament is 15 dtex or less,

[0343] The melt adhesion rate of the monofilament is 10% or less.

[0344] [Item 8]

[0345] The multifilament according to Item 7, wherein,

[0346] The maximum height roughness of the monofilament is 0.10 to 0.50 μm.

[0347] It should be noted that the present invention is not limited to the above-described embodiments. In addition, the present invention is not limited by the above-described effects. Furthermore, the present invention can be variously modified as long as it does not depart from the gist of the present invention.

[0348] Examples

[0349] Next, the present invention will be described in more detail with reference to examples and comparative examples. It should be noted that the present invention is not limited by any of these examples.

[0350] [Example 1]

[0351] A multifilament was produced by the method (successive stretching method) of the first embodiment.

[0352] (Step (A))

[0353] First, a raw material composition was obtained by dry-blending the following materials in the following mixing ratios. Then, the raw material composition was melt-kneaded at 150°C using an extruder to obtain pellets.

[0354] As the poly(3-hydroxyalkanoate) resin (P3HA), (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (content ratio of 3-hydroxybutyrate unit: 94.0 mol%, ratio of 3-hydroxyhexanoate: 6 mol%, crystallization temperature (Tc): 60°C, weight-average molecular weight (Mw): 582936) (P3HB3HH): 100 parts by mass

[0355] Erucamide (EA) as a lubricant having an amide bond: 0.5 part by mass

[0356] Behenamide (BA) as a lubricant having an amide bond: 0.5 part by mass

[0357] Pentaerythritol (PETL) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Neulizer-P) as a crystallization nucleating agent: 1.0 part by mass

[0358] It should be noted that the crystallization temperature and weight-average molecular weight of P3HA were measured by the above method.

[0359] In addition, the content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA were determined as described below.

[0360] First, 2 mL of a mixed solution 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, and the sample was sealed. The sample was heated at 100 °C for 140 minutes while maintaining the sealed state, thereby obtaining a first reaction solution containing methyl esters as decomposition products of P3HA.

[0361] Then, the first reaction solution was cooled, and 1.5 g of sodium bicarbonate was slowly added to the cooled first reaction solution for neutralization, and it was left until the generation of carbon dioxide ceased, thereby obtaining a second reaction solution.

[0362] Furthermore, the second reaction solution and 4 mL of diisopropyl ether were thoroughly mixed to obtain a mixture.

[0363] Next, the mixture was centrifuged to obtain a supernatant.

[0364] Then, the monomer unit composition of the above decomposition product in the supernatant was analyzed by capillary gas chromatography under the following conditions, and the content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA were determined.

[0365] Gas chromatograph: GC-17A manufactured by Shimadzu Corporation

[0366] Capillary chromatographic column: NEUTRA BOND-1 manufactured by GL Science Inc. (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm)

[0367] Carrier gas: He

[0368] Column inlet pressure: 100 kPa

[0369] Sample volume: 1 μL

[0370] Regarding the temperature conditions, the temperature was raised at a rate of 8 °C / min from 100 to 200 °C, and further raised at a rate of 30 °C / min from 200 to 290 °C.

[0371] Then, as Figure 1 shown, the granules were melted with a kneading extruder 102 (single-screw extruder, screw diameter: 25 mm) to obtain a melt.

[0372] Then, the melt was ejected from the spinning nozzle 104 (spinning temperature: 175 °C, number of nozzles: 180, shape of the nozzles: circular, diameter of the nozzles: 0.5 mm), and 180 raw filaments 100A were obtained.

[0373] It should be noted that the flow rate of the melt was adjusted to 3.0 kg / h using the gear pump 103.

[0374] (Process (B))

[0375] In Process B1, the first gas (air) at 23.8 °C was blown onto the 180 molten raw filaments 100A at a speed of 0.22 m / s by the circulation method in the first tank 105, thereby cooling the 180 raw filaments 100A.

[0376] Next, in Process B2, the second gas (air) at 34.1 °C was blown onto the 180 raw filaments 100A at a speed of 0.20 m / s by the backside method in the second tank 106, thereby heating the 180 raw filaments 100A.

[0377] It should be noted that the conditions including "the value (T2 - T1) obtained by subtracting the temperature (T1) of the first gas from the temperature (T2) of the second gas", "T1 - Tc", and "T2 - Tc", the conditions of Process (B1), and the conditions of Process (B2) are shown in Table 1 below.

[0378] Then, the 180 raw filaments 100A were drawn by the first drawing roller unit 107 (560 m / min). After the 180 raw filaments 100A passed through the first conveying roller unit 108 (560 m / min), the second conveying roller unit 109 (560 m / min, 70 °C), the third conveying roller unit 110 (560 m / min), and the fourth conveying roller unit 111 (560 m / min) in sequence, the 180 raw filaments 100A were wound by the first winding roller unit (530 m / min) and stored at room temperature (5 - 35 °C) for 18 hours.

[0379] It should be noted that NDR was set to 175 and the draw ratio was set to 1.05.

[0380] (Process (C))

[0381] As Figure 2As shown, 180 filaments 100A from the first take-up roller section 112 were drawn using the second draw roller section 113 (55.5 m / min, 30°C), drawn using the drawing roller section 114 (110 m / min, 90°C), transported using the heat treatment roller section 115 (100 m / min, 100°C), and taken up using the second take-up roller section 116 (100 m / min), thereby obtaining multifilaments.

[0382] The draw ratio was set to 2.0 times and the relaxation ratio was set to 10%.

[0383] It should be noted that as the draw roller section and the transport roller section, roller sections each composed of two rollers with the same speed and the same temperature were used.

[0384] <Examples 2 to 7, Comparative Example 1>

[0385] The conditions of process (B-1) and process (B-2) were changed to the conditions described in Table 1 below. Otherwise, the same operations as in Example 1 were performed to obtain multifilaments.

[0386] <Comparative Example 2>

[0387] In process (B-2), 180 filaments 100A were cooled, and the conditions of process (B-1) and process (B-2) were changed to the conditions described in Table 1 below. Otherwise, the same operations as in Example 1 were performed. When attempting to obtain multifilaments, multiple filaments broke between the nozzle hole and the first draw roller section 107.

[0388] Therefore, multifilaments could not be obtained.

[0389] <Comparative Example 3>

[0390] In process (B-2), 180 filaments 100A were cooled, and the conditions of process (B-1) and process (B-2) were changed to the conditions described in Table 1 below. Otherwise, the same operations as in Example 1 were performed to obtain multifilaments.

[0391] <Comparative Example 4>

[0392] The conditions of process (B-1) and process (B-2) were changed to the conditions described in Table 1 below. Otherwise, the same operations as in Example 1 were performed. When attempting to obtain multifilaments, multiple filaments broke between the nozzle hole and the first draw roller section 107.

[0393] Therefore, multifilaments could not be obtained.

[0394] <Comparative Example 5>

[0395] The conditions of step (B-2) were changed to the conditions described in Table 1 below, and step (B-1) was not carried out. Otherwise, the same operations as in Example 1 were performed. When attempting to obtain multifilaments, multiple raw filaments broke between the nozzle holes and the first drawing roller section 107.

[0396] Therefore, multifilaments could not be obtained.

[0397] <Comparative Example 6>

[0398] The conditions of step (B-1) were changed to the conditions described in Table 1 below, and step (B-2) was not carried out. Otherwise, the same operations as in Example 1 were performed, and multifilaments were obtained.

[0399] <Spinnability>

[0400] The case where multifilaments could be produced was evaluated as ○, and the case where raw filaments broke and multifilaments could not be produced was evaluated as ×. The results are shown in Table 1 below.

[0401] <Average fineness of monofilaments>

[0402] For each multifilament obtained in the examples and comparative examples, the average fineness of the monofilaments in the multifilament was measured by the above method.

[0403] The average fineness of the monofilaments is shown in Table 1 below.

[0404] <Melting adhesion rate of monofilaments>

[0405] For each multifilament obtained in the examples and comparative examples, the melting adhesion rate of the monofilaments in the multifilament was measured by the above method.

[0406] The melting adhesion rate of the monofilaments is shown in Table 1 below.

[0407] <Arithmetic mean roughness and maximum height roughness of monofilaments>

[0408] For the multifilaments obtained in the examples and comparative examples, the surface roughness of the monofilaments in the multifilament was measured in accordance with JIS B0601:2001, and then the arithmetic mean roughness Ra and the maximum height roughness Rz of the monofilaments were obtained in accordance with JIS B0601:2001.

[0409] It should be noted that in the measurement of the surface roughness of the monofilaments, 5 or more monofilaments were randomly taken from the multifilaments. Then, the surface roughness of each monofilament was measured along the length direction of each monofilament, and the arithmetic mean roughness and the maximum height roughness of each monofilament were obtained. Then, the calculated average value of the arithmetic mean roughness of each monofilament was used as the arithmetic mean roughness Ra of the monofilaments, and the calculated average value of the maximum height roughness of each monofilament was used as the maximum height roughness Rz of the monofilaments.

[0410] A laser microscope was used in this measurement. As this laser microscope, "VK-9500" manufactured by Keyence Corporation was used.

[0411] In addition, the surface roughness was measured under the following conditions.

[0412] Cutoff value: 0.08 mm

[0413] Evaluation length: 80 μm

[0414] The arithmetic mean roughness and the maximum height roughness of the monofilaments are shown in Table 1 below.

[0415] [Table 1]

[0416]

[0417] As shown in Table 1, compared with Comparative Example 1 where the temperature of the first gas in step (B1) is less than (Tc - 45°C), Comparative Example 3 where the temperature of the second gas in step (B2) is less than (Tc - 30°C), and Comparative Example 6 where step (B2) is not performed, the melt adhesion rate of the monofilaments in Examples 1 to 7 within the scope of the present invention is small.

[0418] In addition, in Comparative Example 2 where the temperature of the first gas in step (B1) is greater than (Tc - 30°C), Comparative Example 4 where the temperature of the second gas in step (B2) is greater than (Tc - 10°C), and Comparative Example 5 where step (B1) is not performed, the raw filaments break and it is impossible to produce multifilaments.

[0419] Therefore, according to the present invention, even though the average value of the fineness of the monofilaments is small, it is possible to suppress the breakage of the raw filaments and to suppress the melt adhesion between the monofilaments.

[0420] It should be noted that in the examples of the above Patent Document 2 (International Publication No. 2021 / 206154), it can be considered that since air at the same level of temperature as in Comparative Examples 1 and 3 of this specification was blown onto the raw filaments, the melt adhesion rate of the monofilaments is high.

[0421] Compared with Example 6 where the velocity of the second gas is less than 0.01 m / s, the melt adhesion rate of the monofilaments is further reduced in Examples 1 to 5.

[0422] In addition, compared with Example 5 where the velocity of the first gas is as high as 0.43 m / s, the melt adhesion rate of the monofilaments is further reduced in Examples 1 to 4.

Claims

1. A method for manufacturing a multifilament, which obtains a multifilament having a plurality of filaments by a melt spinning method using a spinneret having a plurality of orifices. This method comprises: Step (A): melting a raw material composition by heating to obtain a melt, and ejecting the melt from the orifices to obtain a plurality of raw filaments in a molten state; Step (B): blowing a gas onto the plurality of raw filaments; The raw material composition contains a poly(3-hydroxyalkanoate) resin, Step (B) has: Step (B1), cooling the plurality of raw filaments in a molten state by blowing a first gas onto the plurality of raw filaments; Step (B2), blowing a second gas onto the plurality of raw filaments cooled in Step (B1), In Step (B1), the temperature of the first gas is (Tc - 45°C) to (Tc - 30°C) [Tc: the crystallization temperature of the poly(3-hydroxyalkanoate) resin], In Step (B2), the temperature of the second gas is higher than the temperature of the first gas and is (Tc - 30°C) to (Tc - 10°C), The average fineness of the filaments is 15 dtex or less.

2. The method for manufacturing a multifilament according to claim 1, wherein, In Step (B1), the temperature of the first gas is (Tc - 40°C) to (Tc - 30°C).

3. The method for manufacturing a multifilament according to claim 1 or 2, wherein, In Step (B1), the velocity of the first gas is 0.1 to 1.0 m / s.

4. The method for manufacturing a multifilament according to claim 1 or 2, wherein, In Step (B2), the velocity of the second gas is 0.005 to 1.5 m / s.

5. The method for manufacturing a multifilament according to claim 1 or 2, wherein, The value obtained by subtracting the temperature of the first gas from the temperature of the second gas is 5 to 25°C.

6. The method for manufacturing a multifilament according to claim 1 or 2, wherein, The poly(3-hydroxyalkanoate) resin contains a poly(3-hydroxybutyrate) resin.

7. A multifilament having a plurality of filaments, wherein, The filaments contain a poly(3-hydroxyalkanoate) resin, The average fineness of the filaments is 15 dtex or less, The melt adhesion rate of the filaments is 10% or less.

8. The multifilament according to claim 7, wherein, The maximum height roughness of the filaments is 0.10 to 0.50 μm.

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