WO2023022015A1

WO2023022015A1 - Stretching multifilament and method for manufacturing same, multifilament and method for manufacturing same, and staple and method for manufacturing same

Info

Publication number: WO2023022015A1
Application number: PCT/JP2022/030015
Authority: WO
Inventors: 毅御林
Original assignee: 株式会社カネカ
Priority date: 2021-08-18
Filing date: 2022-08-04
Publication date: 2023-02-23
Also published as: JPWO2023022015A1; CN117795140A

Abstract

The present invention is a stretching multifilament having 30 or more single threads. The single threads contain a poly(3-hydroxyalkanoate)-based resin and a nucleating agent. The average value of the fineness of the single threads is 30 dtex or lower, and the coefficient of variation for the fineness of the single threads is 33% or lower.

Description

Multifilament for drawing and its manufacturing method, multifilament and its manufacturing method, and staple and its manufacturing method

The present invention relates to a drawing multifilament and its manufacturing method, a multifilament and its manufacturing method, and a staple and its manufacturing method.

In recent years, plastic waste has become a cause of great burden on the global environment, such as the impact on the ecosystem, the generation of toxic gas when burned, and global warming due to the large amount of combustion heat. The development of biodegradable plastics is gaining momentum as a means of solving this problem.

Among these biodegradable plastics, the carbon dioxide emitted when burning biodegradable plastics obtained using plant-derived raw materials was originally in the air, and the amount of carbon dioxide in the atmosphere is increasing. do not. This is called carbon neutral, and under the Kyoto Protocol, which imposes carbon dioxide reduction targets, it is regarded as important and its active use is desired.

Recently, from the viewpoint of biodegradability and carbon neutrality, aliphatic polyester-based resins have attracted attention as biodegradable plastics produced by microorganisms using plant-derived raw materials as carbon sources, and polyhydroxyalkanoate-based resins in particular have attracted attention. It is

Patent Document 1 discloses a multifilament having a plurality of single filaments containing a 3-hydroxyalkanoate polymer.

Moreover, Patent Document 1 discloses obtaining the multifilament by a melt extrusion method.
Specifically, in Patent Document 1, a step (A) of obtaining a plurality of raw yarns in a molten state by discharging a melt by a melt spinning method using a spinning nozzle having four discharge holes; and a step (B) of obtaining a drawing multifilament by cooling the plurality of raw yarns while conveying them.
Then, a multifilament can be obtained by drawing the multifilament for drawing with a roll.

On the other hand, with regard to modified cross-section fibers containing wholly aromatic polyamide, there are known wholly aromatic polyamide modified cross-section fibers that have a coefficient of variation of single filament fineness of 9.0% or less and have a specific relationship (for example, , Patent Document 2).

WO2015/029316 Japanese Patent Application Laid-Open No. 2014-122448

By the way, with respect to multifilaments containing poly(3-hydroxyalkanoate)-based resin in single yarns, multifilaments with thin single yarns and high strength will be required in the future.
Here, if the draw ratio is increased when the drawing multifilament is drawn to obtain the multifilament, the orientation of the polymer in the multifilament increases, and as a result, the strength of the obtained multifilament increases.
However, the present inventors prepared a multifilament for drawing with a thin single yarn in order to obtain a multifilament with a thin single yarn and high strength using a poly(3-hydroxyalkanoate) resin. When an attempt was made to draw the multifilament for drawing at a high draw ratio, the single filament broke during the drawing, and the multifilament could not be obtained.

Therefore, the present invention relates to a multifilament for drawing in which the single yarn contains a poly(3-hydroxyalkanoate) resin, and a multifilament for drawing that is easy to obtain a multifilament with high strength even if the average value of the fineness of the single yarn is small. The first task is to obtain a filament.
A second object of the present invention is to obtain a multifilament whose single yarn contains a poly(3-hydroxyalkanoate)-based resin and whose strength can be easily increased even if the average fineness of the single yarn is small. .
Furthermore, a third object is to obtain a staple in which the multifilament is cut.

A first aspect of the present invention is a drawing multifilament having 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 30 dtex or less,
It relates to the multifilament for drawing, wherein the single yarn has a fineness variation coefficient of 33% or less.
Preferably, the poly(3-hydroxyalkanoate)-based resin contains a poly(3-hydroxybutyrate-based resin).

A second aspect of the invention is a drawn multifilament comprising:
The multifilament has 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 20 dtex or less,
It relates to the multifilament, wherein the single yarn has a fineness variation coefficient of 33% or less.

A third aspect of the present invention is that the multifilament according to claim 3 is cut,
It relates to staples having a length of 20 cm or less.

The fourth aspect of the present invention is a method for producing a multifilament for drawing, which obtains a multifilament for drawing by a melt spinning method,
A step (A) of obtaining 30 or more raw yarns in a molten state by discharging the melt by the melt spinning method using a spinning nozzle having 30 or more discharge holes;
a step (B) of obtaining a drawing multifilament by blowing a gas of 0° C. or more and 50° C. or less to the 30 or more molten raw yarns to cool the 30 or more raw yarns;
The melt contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn in the drawing multifilament is 30 dtex or less,
The step (B) relates to a method for producing a multifilament for drawing, wherein the heat transfer coefficient between the 30 or more molten filaments and the gas is 60 W/(m ² ·K) or more.
Preferably, in step (B), the heat transfer coefficient is set to 125 W/(m ² ·K) or more.
Preferably, in the step (B), the speed of the gas blown onto the 30 or more raw yarns is set to 0.1 m/s or more.

In a fifth aspect of the present invention, the multifilament for drawing is obtained by the method for producing the multifilament for drawing,
The present invention relates to a method for producing a multifilament, comprising a step (C) of obtaining a multifilament by drawing the drawing multifilament by a factor of 1.5 or more in a drawing roll unit.
Preferably, in the step (B), a gas of 0° C. or higher and 50° C. or lower is blown onto the 30 or more molten yarns to cool the 30 or more yarns to 50° C. or lower. Obtaining the multifilament for drawing,
In the step (C), the drawing multifilament is heated and drawn by the drawing roll section.

The sixth aspect of the present invention is to obtain the multifilament by the method for producing the multifilament,
The present invention relates to a staple manufacturing method, wherein a staple having a length of 20 cm or less is obtained by cutting the multifilament.

According to the present invention, with respect to a drawing multifilament in which the single yarn contains a poly(3-hydroxyalkanoate) resin, a drawing multifilament that is easy to obtain a multifilament with high strength even if the average value of the fineness of the single yarn is small. can provide filament.
In addition, according to the present invention, it is possible to provide a multifilament whose single yarn contains a poly(3-hydroxyalkanoate)-based resin and whose strength can be easily increased even if the average fineness of the single yarn is small. .
Further, according to the present invention, staples from which the multifilament is cut can be provided.

Schematic diagram of an apparatus used in steps (A) and (B) of the first embodiment. The schematic of the apparatus used by the process (C) of 1st Embodiment. Schematic diagram of the apparatus used in the second embodiment.

An embodiment of the present invention will be described below.

<Multifilament for drawing>
First, the drawing multifilament according to the present embodiment will be described.
The drawing multifilament according to this embodiment has 30 or more first single yarns.
The first single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average fineness of the first single yarn is 30 dtex or less.
The variation coefficient of fineness of the first single yarn is 33% or less.

A multifilament is obtained by drawing the multifilament for drawing according to the present embodiment.
A staple is obtained by cutting the multifilament.

As described above, with respect to fibers containing wholly aromatic polyamide, wholly aromatic polyamide fibers having a single filament fineness coefficient of variation of 9.0% or less are known (for example, Patent Document 2).
However, poly(3-hydroxyalkanoate)-based resins are difficult to mold, unlike wholly aromatic polyamides.
From this, regarding the drawing multifilament having the first single yarn containing the poly(3-hydroxyalkanoate)-based resin, while reducing the average fineness of the first single yarn, the first single yarn It was difficult to reduce the coefficient of variation of yarn fineness.
Therefore, the present inventors conducted extensive research on a drawing multifilament having 30 or more first single yarns containing a poly(3-hydroxyalkanoate)-based resin, and found that the fineness of the first single yarn We succeeded in setting the average value to 30 dtex or less and the coefficient of variation of the fineness of the first single yarn to 33% or less.
Further, the inventor of the present invention conducted a further intensive study on a drawing multifilament having 30 or more first single yarns containing a poly(3-hydroxyalkanoate)-based resin, and found that the fineness of the first single yarn is 30 dtex or less, and the coefficient of variation of the fineness of the first single yarn is 33% or less, so that even if the average fineness of the single yarn is small, a multifilament with high strength can be easily obtained. It has been found that a multifilament for use can be provided.

The first single yarn is a filament formed from a polymer composition containing a polymer component.

The polymer component contains a poly(3-hydroxyalkanoate)-based resin.
The polymer component may contain other polymers in addition to the poly(3-hydroxyalkanoate)-based resin.
The polymer composition contains a crystal nucleating agent.
The polymer composition may contain other additives in addition to the crystal nucleating agent.

The poly(3-hydroxyalkanoate) resin is a polyester containing 3-hydroxyalkanoic acid as a monomer.
That is, the poly(3-hydroxyalkanoate) resin is a resin containing 3-hydroxyalkanoic acid as a structural unit.
Further, the poly(3-hydroxyalkanoate) resin is a biodegradable polymer.
In addition, "biodegradability" in this embodiment refers to the property of being decomposed into low-molecular-weight compounds by microorganisms in the natural world. Specifically, ISO 14855 (compost) and ISO 14851 (activated sludge) under aerobic conditions, ISO 14853 (aqueous phase) and ISO 15985 (solid phase) under anaerobic conditions, etc. Degradability can be determined. Also, the degradability of microorganisms in seawater can be evaluated by measuring the biochemical oxygen demand.
The poly(3-hydroxyalkanoate)-based resin may be a homopolymer or a copolymer.

The poly(3-hydroxyalkanoate)-based resin preferably contains a structural unit represented by the following formula (1).
[-CHR-CH ₂ -CO-O-] (1)
(In formula (1) above, R represents an alkyl group represented by C _p H _2p+1 , and p represents an integer of 1 to 15.)

The poly(3-hydroxyalkanoate)-based resin preferably contains a poly(3-hydroxybutyrate)-based resin.
The poly(3-hydroxybutyrate) resin is a resin containing 3-hydroxybutyrate as a structural unit. The poly(3-hydroxybutyrate)-based resin may be a homopolymer or a copolymer.

Examples of poly(3-hydroxyalkanoate) resins containing 3-hydroxybutyrate as a structural unit include P3HB, P3HB3HH, P3HB3HV, P3HB4HB, and poly(3-hydroxybutyrate-co-3-hydroxyoctanoate). , poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate) and the like.
Here, P3HB means poly(3-hydroxybutyrate).
P3HB3HH means poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).
P3HB3HV means poly(3-hydroxybutyrate-co-3-hydroxyvalerate).
P3HB4HB means poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

In addition, since P3HB has a function of promoting crystallization of P3HB itself and poly(3-hydroxyalkanoate)-based resins other than P3HB, the poly(3-hydroxyalkanoate)-based resins include P3HB. is preferred.

P3HB, P3HB3HH, P3HB3HV, P3HB4HB and the like are preferable as the poly(3-hydroxyalkanoate)-based resin from the viewpoint of achieving both excellent biodegradability and moldability, but are not particularly limited.
In addition, the poly(3-hydroxyalkanoate)-based resin increases the strength of the multifilament obtained by drawing the drawing multifilament according to the present embodiment, and also increases the strength of the drawing multifilament and the molding of the multifilament. P3HB3HH is preferable from the viewpoint of enhancing workability.

The poly(3-hydroxyalkanoate) resin preferably contains 85.0 mol% to 99.5 mol%, more preferably 85.0 mol% to 97.0 mol% of 3-hydroxybutyrate as a structural unit. Including mol %.
When the poly(3-hydroxyalkanoate) resin contains 85.0 mol % or more of 3-hydroxybutyrate as a structural unit, the rigidity of the multifilament according to the present embodiment is increased.
In addition, since the poly(3-hydroxyalkanoate)-based resin contains 99.5 mol % or less of 3-hydroxybutyrate as a structural unit, the multifilament according to the present embodiment has excellent flexibility.

The polymer component may contain only one type of the poly(3-hydroxyalkanoate)-based resin, or may contain two or more types.
When the poly(3-hydroxyalkanoate) resin contains a copolymer (P3HB3HH, etc.), it may contain two or more copolymers having different average composition ratios of structural units.

The poly(3-hydroxyalkanoate) resin preferably has a weight average molecular weight of 50,000 to 3,000,000, more preferably 50,000 to 1,500,000.
When the weight-average molecular weight of the poly(3-hydroxyalkanoate)-based resin is 3,000,000 or less, the multifilament for drawing according to the present embodiment and the multifilament can be easily molded.
When the poly(3-hydroxyalkanoate) resin has a weight average molecular weight of 50,000 or more, the strength of the multifilament can be increased.
In addition, the weight average molecular weight in this embodiment refers to the one measured from the polystyrene equivalent molecular weight distribution using gel permeation chromatography (GPC) using a chloroform eluent. As the column in the GPC, a column suitable for measuring the molecular weight may be used.

The other polymer is preferably biodegradable.

Other biodegradable polymers include, for example, polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, modified starch, cellulose acetate, chitosan and the like.
The polycaprolactone is a polymer obtained by ring-opening polymerization of ε-caprolactone.
The polymer composition may contain one or two or more other polymers.

The polymer component preferably contains 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more of poly(3-hydroxyalkanoate)-based resin.

The drawing multifilament according to the present embodiment contains a biodegradable polymer, so that even if the multifilament or staple obtained from the drawing multifilament is discarded in the environment, the multifilament or the staple is easily decomposed in the environment, so the burden on the environment can be suppressed.

The polymer composition contains a crystal nucleating agent.
The crystal nucleating agent is a compound capable of promoting crystallization of the poly(3-hydroxyalkanoate)-based resin. Also, the crystal nucleating agent has a higher melting point than the poly(3-hydroxyalkanoate)-based resin.
Examples of the crystal nucleating agent include inorganic substances (boron nitride, titanium oxide, talc, layered silicate, calcium carbonate, sodium chloride, metal phosphate, etc.); sugar alcohol compounds derived from natural products (pentaerythritol, erythritol, gallium lactitol, mannitol, and arabitol, etc.); polyvinyl alcohol; chitin; chitosan; polyethylene oxide; Sebacate); Cyclic compounds having C=O and functional groups selected from NH, S and O in the molecule (indigo, quinacridone, and quinacridone magenta, etc.); Sorbitol derivatives (bisbenzylidene sorbitol, and bis(p- methylbenzylidene) sorbitol, etc.); compounds containing a nitrogen-containing heteroaromatic nucleus (pyridine ring, triazine ring, imidazole ring, etc.) (pyridine, triazine, imidazole, etc.); phosphate ester compounds; bisamides of higher fatty acids; higher fatty acids and branched polylactic acid.
The poly(3-hydroxyalkanoate) resin P3HB can also be used as a crystal nucleating agent.
These may be used alone or in combination of two or more.

As the crystal nucleating agent, from the viewpoint of the effect of improving the crystallization speed of the poly(3-hydroxyalkanoate)-based resin, and from the viewpoint of compatibility and affinity with the poly(3-hydroxyalkanoate)-based resin, Preferred are sugar alcohol compounds, polyvinyl alcohol, chitin and chitosan.
Pentaerythritol is preferred among the sugar alcohol compounds.

The crystal nucleating agent preferably has a crystal structure at room temperature (25°C).
Since the crystal nucleating agent has a crystal structure at room temperature (25° C.), there is an advantage that the crystallization of the poly(3-hydroxyalkanoate)-based resin is further promoted.
Moreover, the crystal nucleating agent having a crystal structure at normal temperature (25°C) is preferably powdery at normal temperature (25°C).
Furthermore, the average particle size of the crystal nucleating agent that is powdery at room temperature (25° C.) is preferably 10 μm or less.

The content of the crystal nucleating agent in the polymer composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and 0.5 parts by mass with respect to 100 parts by mass of the poly(3-hydroxyalkanoate) resin. Part by mass or more is more preferable. The content of the crystal nucleating agent in the polymer composition is 0.05 parts by mass or more with respect to 100 parts by mass of the poly(3-hydroxyalkanoate)-based resin, so that the poly(3-hydroxyalkanoate)-based resin is crystallized. has the advantage of being able to promote
The content of the crystal nucleating agent in the polymer composition is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and 5 parts by mass or less with respect to 100 parts by mass of the poly(3-hydroxyalkanoate) resin. More preferred. The content of the crystal nucleating agent in the polymer composition is 10 parts by mass or less with respect to 100 parts by mass of the poly(3-hydroxyalkanoate)-based resin, so that the multifilament for drawing is produced from the melt obtained by melting the polymer composition. At the time of stretching, the viscosity of the melt can be lowered, and as a result, there is an advantage that the production of the multifilament for drawing is facilitated.
P3HB is a poly(3-hydroxyalkanoate) resin and can also function as a crystal nucleating agent. Therefore, when the polymer composition contains P3HB, the amount of P3HB is hydroxyalkanoate) resin and the crystal nucleating agent.

Other additives include, for example, lubricants, stabilizers (antioxidants, ultraviolet absorbers, etc.), colorants (dyes, pigments, etc.), plasticizers, flame retardants, inorganic fillers, organic fillers, antistatic agents. etc.

The polymer composition preferably contains the lubricant. By including a lubricant in the first single yarn, the lubricity of the first single yarn is improved, and fusion between the first single yarns can be suppressed.
Examples of the lubricant include compounds having an amide bond.
The compound having an amide bond preferably contains one or more selected from lauric acid amide, myristic acid amide, stearic acid amide, behenic acid amide, and erucic acid amide.

The content of the lubricant in the polymer composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the polymer component. When the content of the lubricant in the polymer composition is 0.05 parts by mass or more with respect to 100 parts by mass of the polymer component, there is an advantage that the lubricity of the first single yarn is excellent.
The content of the lubricant in the polymer composition is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less, and most preferably 5 parts by mass or less, relative to 100 parts by mass of the polymer component. . The advantage is that the content of the lubricant in the polymer composition is 12 parts by mass or less with respect to 100 parts by mass of the polymer component, thereby suppressing bleeding out of the lubricant onto the surface of the drawing multifilament, multifilament, or staple. There is

A biodegradable plasticizer is preferable as the plasticizer from the viewpoint of improving the moldability of the multifilament for drawing.
Biodegradable plasticizers include, for example, polyglycerin fatty acid ester (PGFE) (for example, "Tirabazole" manufactured by Taiyo Kagaku Co., Ltd.), mixed radical dibasic acid ester (for example, "DAIFATTY" manufactured by Daihachi Chemical Industry Co., Ltd.). ”), glycerin fatty acid esters (eg, “Rikemal” manufactured by Riken Vitamin Co., Ltd.), and the like.

In addition, from the viewpoint of enhancing the moldability of the drawing multifilament, the plasticizer becomes a supercritical fluid under the temperature and pressure when the material is kneaded while being heated in step (A) described later, and A plasticizer that becomes a gas at normal temperature and pressure (25° C., 1 atm) is also preferred.
Such plasticizers include, for example, nitrogen (N ₂ ), carbon dioxide, lower aliphatic hydrocarbons, and the like.
Examples of the lower aliphatic hydrocarbons include propane, butane, and isobutane.

The drawing multifilament according to the present embodiment has 30 or more first single yarns, preferably 30 to 500,000, more preferably 50 to 300,000.

The shape of the cross section of the first single yarn is, for example, a circular shape (a concept including perfect circles, substantially circular shapes, elliptical shapes, and substantially elliptical shapes).

The average fineness of the first single yarn is 30 dtex or less.
The average fineness of the first single yarn is preferably 20 dtex or less, more preferably 10 dtex or less.
The average fineness of the first single yarn is preferably 1.5 dtex or more, more preferably 3.0 dtex or more.

It should be noted that in the present embodiment, the fineness of the yarn means the thickness of the yarn and is defined as the mass per unit length. Mass (g) per 10,000 m is expressed in units (dtex).

In this embodiment, the average fineness of the first single yarn can be obtained as follows.
First, the fineness (total fineness) of the drawing multifilament is measured. Also, the number of first single yarns contained in the drawing multifilament is obtained.
Then, the average value of the fineness of the first single yarn is obtained from the following formula.
Average fineness of first single yarn = fineness of drawing multifilament / number of first single yarns contained in drawing multifilament

The variation coefficient of fineness of the first single yarn is 33% or less.
The variation coefficient of fineness of the first single yarn is preferably 32% or less, more preferably 30% or less, and still more preferably 28% or less.
The variation coefficient of the fineness of the first single yarn is preferably small, and the variation coefficient of the fineness of the first single yarn is, for example, 5% or more, more specifically 10% or more.

By setting the coefficient of variation of the fineness of the first single yarn to 33% or less, the stability of the doubling process ("doubling" will be described later) and the drawing process is improved. Further, since the coefficient of variation of the fineness of the first single yarn is 33% or less, the mechanical properties (strength, etc.) of the multifilament obtained by drawing are improved.

That is, when the coefficient of variation of the fineness of the first single yarn is 33% or less, extremely thin first single yarn and extremely thick first single yarn are less likely to be included in the drawing multifilament.
By making it difficult for the drawing multifilament to contain extremely thin yarns, the stability of the yarn doubling process (“doubling yarn” will be described later) and the drawing process is improved. Specifically, the winding roll portion (specifically, the bobbin of the winding roll portion) (“winding roll portion” and “bobbin” will be described later) (“bobbin” includes “paper tube” It is a concept.) Improves the drawing performance of multifilaments for drawing and multifilaments. In addition, yarn breakage is suppressed when drawing tension is applied to the drawing multifilament. Furthermore, the winding of the drawing multifilament on the drawing roll portion (the “drawing roll portion” will be described later) is improved. In addition, sagging of the drawing multifilament and the multifilament during transportation is suppressed.
In addition, since it is difficult for the drawing multifilament to contain extremely thick yarns, drawing stress uniformly acts on the drawing multifilament when the drawing multifilament is drawn, thereby suppressing drawing unevenness. As a result, the fineness of the first single yarn is uniformly reduced, and the mechanical properties (strength, etc.) of the resulting multifilament are improved.

The variation coefficient of the fineness of the first single yarn can be obtained as follows.
First, the drawing multifilament is cut with a knife so as to be perpendicular to the longitudinal direction, and the cut surface is photographed with a microscope to obtain a cross-sectional photograph.
Next, in the cross-sectional photograph, the cross-sectional area of each first single yarn is measured for all the first single yarns constituting the multifilament for drawing. Alternatively, 30 or more first single yarns are randomly selected from the drawing multifilament, and the cross-sectional area of each first single yarn is measured. That is, it may not be practical to measure the cross-sectional area of each first single yarn for all the first single yarns constituting the drawing multifilament, so the first single yarn from the drawing multifilament Thirty or more yarns may be randomly selected and the cross-sectional area of each first single yarn measured.
Then, from the cross-sectional areas of the first single yarns, the arithmetic mean value of the cross-sectional areas of the first single yarns and the standard deviation of the cross-sectional areas of the first single yarns are obtained.
Next, the coefficient of variation of the fineness of the first single yarn is obtained from the following formula.
Coefficient of variation of the fineness of the first single yarn (%) = (standard deviation of the cross-sectional area of the first single yarn / arithmetic mean value of the cross-sectional area of the first single yarn) × 100 (%)
The method for measuring the cross-sectional area is also described in JIS L 1015:2021 "Test method for chemical fiber staple", "8.5.3 Fineness fluctuation rate".

From the viewpoint of suppressing fusion between adjacent first single yarns and suppressing separation of adjacent first single yarns due to static electricity, the drawing multifilament according to the present embodiment is , it is preferred to further have a spinning oil on the surface of the first single yarn.
Examples of the spinning oil include cationic surfactants, anionic surfactants, nonionic surfactants, refined esterified oils, mineral oils, poly(oxyethylene)alkyl ethers, silicone oils, and paraffin waxes. These may be used alone or in combination of two or more.
From the viewpoint of suppressing fusion between adjacent first single yarns, silicone oil is preferable as the spinning oil.
From the viewpoint of suppressing the separation of adjacent first single yarns due to static electricity, the spinning oil agent is preferably an anionic surfactant or a nonionic surfactant.
As the spinning oil, for example, a spinning oil containing a silicone oil and an anionic surfactant (for example, "Polymax FKY" manufactured by Marubishi Yuka Co., Ltd.) can be used.

<Multifilament>
The multifilament according to this embodiment is a drawn multifilament.
The multifilament according to this embodiment has 30 or more second single yarns.
The second single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average fineness of the second single yarn is 20 dtex or less.
The variation coefficient of fineness of the second single yarn is 33% or less.

The second single yarn is obtained by forming the polymer composition into a filament.

The multifilament according to this embodiment has 30 or more second single yarns, preferably 30 to 500,000, more preferably 50 to 300,000.

The cross-sectional shape of the second single yarn is, for example, a circular shape (a concept including perfect circles, substantially circular shapes, elliptical shapes, and substantially elliptical shapes).

The average fineness of the second single yarn is 20 dtex or less.
In addition, if the average value of the fineness of the second single yarn is 20 dtex or less, the average fineness of the second single yarn is determined from the required quality in the use of the multifilament or the required quality in the staple obtained from the multifilament. value may be determined.
The average value of fineness of the second single yarn is preferably over 1.0 dtex, more preferably 1.2 dtex or more, further preferably 1.5 dtex or more.
The average fineness of the second single yarn is preferably 18 dtex or less, more preferably 16 dtex or less.

In this embodiment, the average fineness of the second single yarn can be obtained as follows.
First, the fineness (total fineness) of the multifilament is measured. Also, the number of second single yarns included in the multifilament is obtained.
Then, the average value of the fineness of the second single yarn is obtained from the following formula.
Average fineness of second single yarn = fineness of multifilament / number of second single yarns contained in multifilament

The variation coefficient of fineness of the second single yarn is 33% or less.
The variation coefficient of fineness of the second single yarn is preferably 32% or less, more preferably 30% or less, and even more preferably 28% or less.
The variation coefficient of the fineness of the second single yarn is preferably small, and the variation coefficient of the fineness of the second single yarn is, for example, 5% or more, more specifically 10% or more.

The variation coefficient of the fineness of the second single yarn can be obtained as follows.
First, the multifilament is cut with a knife so as to be perpendicular to the longitudinal direction, and the cut surface is photographed with a microscope to obtain a cross-sectional photograph.
Next, in the cross-sectional photograph, the cross-sectional area of each second single yarn is measured for all the second single yarns constituting the multifilament. Alternatively, 30 or more second single yarns are randomly selected from the multifilament, and the cross-sectional area of each second single yarn is measured. That is, since it may not be practical to measure the cross-sectional area of each second single yarn for all the second single yarns that make up the multifilament, 30 second single yarns from the multifilament The cross-sectional area of each of the second single yarns may be measured by selecting them at random.
Then, from the cross-sectional areas of the second single yarns, the arithmetic mean value of the cross-sectional areas of the second single yarns and the standard deviation of the cross-sectional areas of the second single yarns are obtained.
Next, the coefficient of variation of the fineness of the second single yarn is obtained from the following formula.
Second single yarn fineness coefficient of variation (%) = (second single yarn cross-sectional area standard deviation / second single yarn cross-sectional area arithmetic mean) x 100 (%)
The method for measuring the cross-sectional area is also described in JIS L 1015:2021 "Test method for chemical fiber staple", "8.5.3 Fineness fluctuation rate".

The average tensile strength of the second single yarn is preferably 1.5 cN/dtex or more, more preferably 1.7 cN/dtex or more, and still more preferably 2.0 cN/dtex or more.
Although it is preferable that the average value of the tensile strength of the second single yarn is large, the tensile strength of the second single yarn is, for example, 20 cN/dtex or less (specifically, 10 cN/dtex or less).

The average tensile strength of the second single yarn can be obtained as follows.
First, the tensile strength of each of the second single yarns constituting the multifilament is measured. Alternatively, ten or more second single yarns are randomly selected from the multifilament, and the tensile strength of each second single yarn is measured. That is, since it may not be practical to measure the tensile strength of each second single yarn for all the second single yarns constituting the multifilament, 10 second single yarns from the multifilament The above may be randomly selected and the tensile strength of each second single yarn may be measured.
Then, the arithmetic average value of the tensile strength of the second single yarns is obtained from the tensile strength of each of the second single yarns, and this value is taken as the average value of the tensile strength of the second single yarns.

The tensile strength of each second single yarn can be measured at an initial length of 20 mm and a speed of 20 mm/min based on JIS L 1015:2021 "Chemical fiber staple test method".
For example, the tensile strength of each second single yarn can be determined as follows.
First, using a tension measuring device Autograph AG-I (manufactured by Shimadzu Corporation), the load (cN) at the time of cutting each second single yarn is measured under the following conditions.
Initial length of each second single yarn: 20 mm
Tensile speed: 20mm/min
Load cell: A load cell with a rated capacity of 5N Also, the fineness of each second single yarn is measured. The fineness of each second single yarn can be measured, for example, by the autobibroscopy method.
Then, the tensile strength of each second single yarn is calculated by the following formula.
Tensile strength of each second single yarn (cN/dtex) = load at breaking of each second single yarn (cN)/fineness of each second single yarn

<Staple>
The staple according to this embodiment is a staple obtained by cutting the multifilament according to this embodiment.
The staple length (also referred to as “fiber length”) according to the present embodiment is 20 cm or less, specifically 0.1 to 10 cm.
The length of the staple is JIS L1015: 2021 "Chemical fiber staple test method""8.4 fiber length""8.4.1 average fiber length""c) C method (substitution method)" It means the "average value of fiber length" obtained.

The staple according to this embodiment may be a crimped yarn (crimped yarn). In other words, the staple according to this embodiment may have crimps.
The length of the crimped staple (fiber length) can be appropriately set depending on the application. It may be 5 to 7.6 cm.

From the viewpoint of improving the card passability when obtaining a nonwoven fabric from staples, the viewpoint of improving the texture of the obtained nonwoven fabric, and the quick drying property of the nonwoven fabric by reducing the water absorption rate of the nonwoven fabric, The number of crimps of the staple is preferably 5 to 25/25 mm, more preferably 6 to 20/25 mm, even more preferably 7 to 18/25 mm, and 8 to 17. /25 mm is particularly preferred.
The number of crimps of the staple means the number of crimps per staple length of 25 mm. The number of crimps of staples means the average value of the number of crimps of 15 staples selected at random. When the number of staples is less than 15, it means the average number of crimps of all staples. The number of crimps of each staple can be obtained by counting the number of crimped crimps in a staple length of 25 mm using a microscope. In addition, when the length of each staple is less than 25 mm, the number of crimp peaks in the entire length may be counted using a microscope to obtain the number of crimps per 25 mm.

<Method for producing multifilament for drawing, and method for producing multifilament>
The method for producing a multifilament for drawing according to the present embodiment is a method for obtaining a multifilament for drawing by a melt spinning method.
In the method for producing a drawing multifilament according to the present embodiment, a spinning nozzle having 30 or more discharge holes is used to discharge the melt by the melt spinning method, thereby producing 30 or more molten raw yarns. A step (A) of obtaining, and a step of obtaining a drawing multifilament by blowing a gas of 0° C. or more and 50° C. or less to 30 or more of the raw yarns in a molten state to cool the 30 or more yarns ( B).
The melt contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average fineness of single yarns in the multifilament for drawing is 30 dtex or less.
In the step (B), the heat transfer coefficient between the 30 or more molten filaments and the gas is set to 60 W/(m ² ·K) or more.

Further, in the step (B), it is preferable that the speed of the gas that is blown onto the 30 or more raw yarns is 0.3 m/s or more.

In the step (A), the melt is the polymer composition in a molten state.

The method for producing a multifilament according to this embodiment obtains the multifilament for drawing by the method for producing a multifilament for drawing according to this embodiment.
Moreover, the method for producing a multifilament according to the present embodiment has a step (C) of obtaining a multifilament by drawing the drawing multifilament by a factor of 1.5 or more with a drawing roll unit.

Preferably, in the step (B), a gas of 0° C. or higher and 50° C. or lower is blown onto the 30 or more molten raw yarns to cool the 30 or more raw yarns to 50° C. or lower. The drawing multifilament is obtained, and in the step (C), the drawing multifilament is heated and drawn by the drawing roll section.

(First Embodiment: Sequential Stretching Method)
Hereinafter, a method for producing a multifilament for drawing and a multifilament by a sequential drawing method (also referred to as a “post-drawing method”) will be taken as an example, and the method for producing a multifilament for drawing according to the first embodiment and a method of manufacturing the multifilament will be described with reference to FIGS.

(Step (A))
As shown in FIG. 1 , in the step (A), first, the molten material is charged into the material charging portion 101 .
Next, the melt is obtained by heating and kneading the materials charged from the material charging section 101 in the kneading extruder 102 .
A screw extruder is preferably used as the kneading extruder 102 . The kneading extruder 102 may be a single screw extruder or a twin screw extruder.

Then, using a spinning nozzle 104 having 30 or more discharge holes, the melt obtained by the kneading extruder 102 is discharged from the 30 or more discharge holes, thereby forming 30 yarns 100A in a molten state. Get more.
The flow rate of the melt discharged from the plurality of discharge holes of the spinning nozzle 104 is adjusted by the gear pump 103 .

The temperature of the spinning nozzle 104 is, for example, 140-180°C.

The spinning nozzle 104 has 30 or more discharge holes, preferably 30 to 10,000 discharge holes, and more preferably 30 to 5,000 discharge holes.
The shape and size of each discharge hole are selected according to the properties (for example, appearance, fineness, strength, cross-sectional shape, etc.) required for the drawing multifilament. The shape of the discharge hole is, for example, a circular shape (a concept including perfect circles, substantially circular shapes, elliptical shapes, and substantially elliptical shapes).
The area of each discharge hole is determined to be, for example, 10 to 5000 times the cross-sectional area of the first single yarn in the drawing multifilament.
In this embodiment, the shapes of the ejection holes are substantially the same. Moreover, the areas of the discharge holes are substantially the same.
The area of each discharge hole is preferably 1.0×10 ⁻³ to 20 mm ² , more preferably 5.0×10 ⁻³ to 10 mm ² .

The speed at which the melt is discharged from the spinning nozzle 104 (hereinafter also referred to as “spinning nozzle flow speed”) is preferably 0.02 m/min to 20 m/min, more preferably 0.05 m/min to 10 m/min, 0.1 m/min to 5.0 m/min is more preferable.

In the first embodiment, the spinning oil may be applied to the surface of each of the 30 or more cooled raw yarns 100A.

(Step (B))
In the step (B), a gas of 0° C. or more and 50° C. or less is blown to the 30 or more molten yarns obtained in the step (A) to cool the 30 or more yarns. , to obtain a drawing multifilament.
In the first embodiment, the raw yarn 100A is cooled in the first cooling box 105 with a gas of 0° C. or more and 50° C. or less.
Further, in the first embodiment, the raw yarn 100A cooled in the first cooling box 105 may be further cooled in the second cooling box 106 with a gas of 0° C. or more and 50° C. or less.

In the step (B), the temperature of the gas that is blown onto the plurality of raw yarns 100A in the molten state obtained in the step (A) is 0 to 50°C, preferably 0 to 40°C, more preferably 15 to 40°C.
When the temperature of the gas is 0° C. or higher, mutual fusion of the first single yarns of the drawing multifilament is suppressed. In addition, since the temperature of the gas is 0° C. or higher, the mechanical properties (strength, etc.) of the multifilament for drawing are improved.
When the temperature of the gas is 50° C. or lower, unevenness in the fineness of the first single yarn is suppressed (the coefficient of variation of the first single yarn can be reduced). Moreover, since the temperature of the gas is 50° C. or less, it is possible to suppress the yarn breakage of some of the plurality of raw yarns 100A.
Moreover, in the step (B), the temperature of the gas is preferably equal to or higher than the glass transition temperature of the polymer composition. When the temperature of the gas is equal to or higher than the glass transition temperature of the polymer composition, the polymer composition is easily plastically deformed and the raw yarn 100A is difficult to cut.
In addition, "the temperature of the gas blown onto the plurality of the raw yarns 100A in the molten state obtained in the step (A)" means the temperature of the gas when the gas comes into contact with the raw yarns 100A. .

In the step (B), the speed of the gas blown onto the 30 or more raw yarns is preferably 0.10 m/s or more, more preferably 0.20 to 5.0 m/s, and still more preferably 0.20 to 3.0 m/s, more preferably 0.30 to 3.0 m/s, particularly preferably 0.32 to 3.0 m/s.
When the speed of the gas is 0.10 m/s or more, the cooling effect of the gas is easily exhibited.
When the speed of the gas is 5.0 m/s or less, the molten yarn 100A discharged from the spinning nozzle 104 is suppressed from being shaken by the gas. As a result, fusion between the raw yarns 100A in a molten state and/or yarn breakage is suppressed, that is, spinning stability is enhanced.
It should be noted that the "velocity of the gas blown onto the plurality of raw yarns 100A in the molten state obtained in the step (A)" means the speed of the raw yarns 100A when the gas comes into contact with the raw yarns 100A. means relative velocity to

Examples of the gas include air, inert gas (nitrogen gas, argon gas, etc.), water vapor, and the like.

By the way, the heat flow Q between the gas and the solid is calculated by the following formula with the heat transfer coefficient h between the gas and the solid, the contact area A between the gas and the solid, and the temperature difference ΔT between the gas and the solid in a relationship.
Q = h x A x ΔT
Therefore, by increasing the heat transfer coefficient h between the gas and the solid, the heat flow Q between the gas and the solid can be increased.
Therefore, by increasing the heat transfer coefficient between the 30 or more molten yarns and the gas, the 30 or more molten yarns can be sufficiently cooled.
In the step (B), the heat transfer coefficient between the 30 or more molten yarns and the gas is 60 W/(m ² ·K) or more, preferably 65 W/(m ² ·K) or more, More preferably 70 W/(m ² ·K) or more, still more preferably 125 W/(m ² ·K) or more, particularly preferably 130 W/(m ² ·K) or more, most preferably 135 W/(m ² ·K) ) or more.
Further, in the step (B), the heat transfer coefficient between the 30 or more molten yarns and the gas is set to, for example, 500 W/(m ² ·K) or less (more specifically, 350 W/ (m ² · K) or less).

The heat transfer coefficient can be obtained from the temperature T of the gas, the velocity u of the gas, and the cross-sectional diameter d of the yarn.

The cross section of the raw yarn means a cross section perpendicular to the longitudinal direction of the raw yarn.
The value of the "discharge hole diameter" is used as the "diameter of the cross section of the raw yarn".
When the shape of the discharge hole is not a perfect circle, the area of the discharge hole is obtained, and from the area of the discharge hole, the diameter of the discharge hole assuming that the discharge hole is a perfect circle is calculated. The calculated value is used as the "cross-sectional diameter of the raw yarn".

Specifically, the heat transfer coefficient can be obtained by the following procedures [1] to [5].

[1]
From the temperature T of the gas, the density ρ of the gas, the viscosity coefficient μ of the gas, the specific heat C _p of the gas, and the thermal conductivity λ of the gas are obtained.

For example, when the gas is air, the gas density ρ (kg/m ³ ) can be obtained from the following formula and the gas temperature T (K).
ρ = 351.99/T + 344.84/T ²

For example, when the gas is air, the viscosity coefficient μ (Pa·s) of the gas can be obtained from the following formula and the temperature T (K) of the gas.
μ = (1.4592×10 ⁻⁶ ×T ^3/2 )/(109.10+T)

The specific heat C _p (J/(kg·K)) of the gas can be obtained from the following formula and the temperature T (K) of the gas, for example, when the gas is air.
Cp = 1030.5 - 0.19975 x T + 3.9734 x 10 ^-4 x T ²

The thermal conductivity λ(W/(m·K)) of the gas can be obtained from the following formula and the temperature T(K) of the gas, for example, when the gas is air.
λ=(2.3340×10 ⁻³ ×T ^3/2 )/(164.54+T)

In the case where the gas is other than air, similarly to air, the density ρ of the gas, the viscosity coefficient μ of the gas, the specific heat of the gas C _p , and the thermal conductivity λ of the gas can be determined.

[2]
The Reynolds number Re is obtained from the following equation, the gas density ρ, the gas velocity u, the diameter of the cross section of the fiber (the diameter of the discharge hole) d, and the viscosity coefficient μ of the gas.
Re=ρ×u×d/μ

[3]
The Prandtl number Pr is obtained from the following equation, the viscosity coefficient μ of the gas, the specific heat C _p of the gas, and the thermal conductivity λ of the gas.
Pr = μ×Cp/λ

[4]
Nusselt number Nu is obtained from the following formula, Reynolds number Re, and Prandtl number Pr.
Nu = C x ^Rem x Pr ^1/3
Note that C and m are coefficients determined by the Reynolds number Re. Table 1 below shows C and m with respect to the Reynolds number Re.

[5]
The heat transfer coefficient h is obtained from the following formula, the Nusselt number Nu, the diameter of the cross section of the yarn (the diameter of the discharge hole) d, and the thermal conductivity λ of the gas.
h=Nu×λ/d

In addition, for the calculations of [1] to [5] above, "Science.Tools" on Cat Tech Lab's website [searched July 26, 2021] (URL: https://cattech-lab.com/science -tools/) etc. can be used.

As a method of blowing gas onto 30 or more of the raw yarns in a molten state, in a longitudinal direction view of the raw yarn (cross-sectional view of the raw yarn perpendicular to the longitudinal direction of the raw yarn), from at least four directions It is preferable to blow gas onto the raw yarn (so-called circular quenching method).
In the circular quenching method, gas is blown onto the raw yarn from preferably 8 or more directions, more preferably 16 or more directions.
It is preferable that the direction in which the gas is blown onto the raw yarn is between the direction perpendicular to the direction of flow of the raw yarn and the direction of flow of the raw yarn.
The distance between the ejection hole of the spinning nozzle 104 and the position where the gas comes into contact with the raw yarn ejected from the ejection hole is determined according to the required properties of the drawing multifilament.
By setting the degree of orientation and the degree of crystallinity of the raw yarn 100A within appropriate ranges, the process for obtaining the multifilament from the drawing multifilament is stabilized, and the mechanical properties of the multifilament are improved.
In the step (B), it is preferable that the gas contacting the raw yarn is discharged outside the cooling box along the flow direction of the raw yarn. In order to discharge the gas coming into contact with the raw yarn outside the cooling box along the flow direction of the raw yarn, for example, a rectifying plate, a rectifying fin, an ejector, a venturi tube, a transvector manufactured by Nijigi Co., Ltd., etc. are used. be able to.

In the step (B), 30 or more raw yarns 100A cooled with a gas of 0° C. or more and 50° C. or less are taken up by the first take-up roll section 107 . The first take-up roll section 107 is composed of two rolls. The first take-up roll unit 107 may be composed of one roll, or may be composed of three or more rolls.
In the first embodiment, the first transport roll unit 108, the second transport roll unit 109, the third transport roll unit 110, and the fourth transport roll unit 111 are used to perform the first transport roll unit. The 30 or more raw yarns 100A taken by the take-up roll unit 107 are transported, and the 30 or more raw yarns 100A transported by the

transport roll units

108, 109, 110, and 111 are transferred to the first winding roll unit 112. to obtain a multifilament for drawing.
The first winding roll section 112 has a bobbin. A bobbin is a concept that also includes a paper tube. The bobbin may or may not have a collar.
Specifically, in the step (C), the raw yarn 100A is wound on the bobbin of the first winding roll portion 112 to obtain the drawing multifilament.
Each transport roll unit is composed of two rolls in FIG. 1, but may be composed of one roll, or may be composed of three or more rolls.

In the step (B), the 30 or more raw yarns 100A are cooled to preferably 70°C or lower, more preferably 60°C or lower, even more preferably 50°C or lower, and particularly preferably 40°C or lower. In the step (B), the 30 or more raw yarns 100A are cooled to, for example, 0°C or higher, preferably 10°C or higher.
Moreover, in the step (B), 30 or more of the raw yarns 100A are preferably cooled to a temperature equal to or higher than the glass transition temperature of the polymer composition.
In the step (B), the 30 or more raw yarns may be cooled to 70°C or lower by blowing a gas of 0°C or higher and 50°C or lower. Further, in the step (B), the 30 or more raw yarns 100A are cooled to some extent by blowing a gas of 0° C. or more and 50° C. or less, and then the first take-up roll portion 107 The 30 or more raw yarns 100A may be cooled to 70° C. or less by being cooled by ambient air while being transported to the winding roll section 112 .

In order to draw the drawing multifilament in the step (C), in the step (B), the 30 or more raw yarns 100A are not substantially drawn, or the 30 or more raw yarns 100A are not drawn. Less stretching is preferred.
That is, the draw ratio in the step (B) is preferably 1.5 times or less, more preferably 1.2 times or less, and still more preferably 1.1 times or less.
The draw ratio in the step (B) can be determined by the following formula.
Stretch ratio in the step (B) = speed of the transport roll (m/min) / speed of the take-up roll used in the step (B) ("first take-up roll 107" in the first embodiment) (m/min)

The speed (m/min) of the take-up roll used in the step (B) is set to the take-up roll used in the step (B) ("first take-up roll 107" in the first embodiment). It is the length per unit time of 30 or more yarns 100A to be taken.
The speed of the transport roll portion is the length per unit time of the 30 or more raw yarns 100A transported by the transport roll portion.
When a plurality of transport roll units are used, the highest speed among the plurality is defined as the "speed of the transport roll units".

Regarding the fineness of the first single yarn of the multifilament for drawing, the following relational expression approximately holds true.
The fineness (dtex) of the first single yarn of the drawing multifilament = (((a x 1000/60)/b x 10000)/c)/d
a: Amount of the melt discharged from the spinning nozzle 104 (kg/h)
b: the speed (m/min) of the take-up roll unit (“first take-up roll unit 107” in the first embodiment) used in the step (B)
c: number of ejection holes of the spinning nozzle 104
d: draw ratio (-) in the step (B)
Therefore, the fineness of the first single yarn of the multifilament for drawing can be adjusted by adjusting the above b and the like.

In the step (B) in FIG. 1, 30 or more of the raw yarns 100A are wound by the first winding roll unit 112, but in the first embodiment, 30 or more of the raw yarns 100A are wound. The multifilament for drawing may be obtained by storing the multifilament in a container without being wound by the first winding roll unit 112 .

When the transport roll part is not used, the draw ratio in the step (B) is 1.0 times.

(Step (C))
As shown in FIG. 2 , in the step (C), the drawing multifilament 100B is heated and drawn by the drawing roll section 114 .

In the step (C), the drawing multifilament is taken off from the first take-up roll part 112 by the second take-up roll part 113 .
Next, in step (C), the drawing multifilament 100B taken by the second take-up roll section 113 is drawn by the drawing roll section 114 .
Then, in step (C), the drawing multifilament 100B drawn by the drawing roll unit 114 is wound by the second take-up roll unit 116 to obtain a multifilament.
The second take-up roll section 116 has a bobbin. A bobbin is a concept that also includes a paper tube. The bobbin may or may not have a collar.
Specifically, in the step (C), the multifilament is obtained by winding the drawn multifilament 100B on the bobbin of the second winding roll section 116 .
2, the drawing multifilament 100B drawn by the drawing roll unit 114 is wound by the second take-up roll unit 116 to obtain a multifilament. A multifilament may be obtained without winding the drawing multifilament 100B drawn in the second winding roll section 116 .
Further, in the step (C), the drawing multifilament 100B drawn by the drawing roll section 114 may be transported by the take-off roll section 115 .

The second take-up roll section 113 is composed of two rolls. The second take-up roll unit 113 may be composed of one roll, or may be composed of three or more rolls.
In the step (C), the drawing multifilament 100B is preferably heated by the second take-up roll section 113 .
In the step (C), the drawing multifilament 100B is heated by the second take-up roll unit 113 to increase the orientation of the polymer component contained in the first single yarn of the drawing multifilament 100B. It becomes easier to adjust the temperature of the first single yarn so that it is within a suitable temperature range, and as a result, it becomes easier to increase the orientation of the polymer component of the first single yarn.
The temperature of the second take-up roll portion 113 is preferably 15°C or higher and lower than 60°C, more preferably 20 to 55°C.
In addition, when the temperature of the environment in which the step (C) is performed is 15° C. or higher, the drawing multifilament 100B may not be heated by the second take-up roll portion 113 .

The stretching roll section 114 is composed of two rolls. The stretching roll unit 114 may be composed of one roll, or may be composed of three or more rolls.
In the step (C), the drawing multifilament 100B may or may not be heated by the drawing roll section 114 . That is, in the first embodiment, the stretching roll section 114 may also serve as the heat treatment roll section.
In the step (C), the drawing multifilament 100B is heated by the drawing roll unit 114 to promote crystallization of the polymer component contained in the first single yarn of the drawing multifilament 100B, or The heat resistance of the polymer component contained in one single yarn can be improved.
The temperature of the stretching roll section (heat treatment roll section) 114 is preferably 30 to 100.degree. C., more preferably 40 to 90.degree.

In the first embodiment, it is preferable that the take-off roll portion 115 also serves as the heat treatment roll portion.
The take-off roll section 115 (heat treatment roll section 115) is composed of two rolls. The take-off roll section 115 (heat treatment roll section 115) may be composed of one roll, or may be composed of three or more rolls.
In the step (C), the drawing multifilament 100B is heated by the heat treatment roll unit 115 to promote crystallization of the polymer component contained in the first single yarn of the drawing multifilament 100B, or The heat resistance of the polymer component contained in one single yarn can be improved.
The temperature of the take-off roll portion (heat treatment roll portion) 115 is preferably 30 to 100.degree. C., more preferably 40 to 90.degree.
Both or only one of the stretching rolls 114 and the take-off rolls 115 may be heat treatment rolls.

In the step (C) of the first embodiment, the take-up roll section 113, the drawing roll section 114, and the take-off roll section 115 heat the first single yarn. In order to achieve the purpose of controlling the orientation, crystallization, and heat resistance of the polymer component, the first single yarn may be appropriately heated.
For example, the first single yarn may be heated by the first winding roll section 112 .
Alternatively, the first single yarn may be heated by the second winding roll portion 116 to obtain a multifilament.
The first single yarn may be heated in all roll sections from the first winding roll section 112 to the second winding roll section 116 . Further, the first single yarn is heated only in some of all the rolls from the first take-up roll 112 to the second take-up roll 116, and the first single yarn is heated in the other rolls. A mode in which the first single yarn is not heated may be used.
In addition, it is preferable to control the heating of the first single yarn in the rolls at each of the rolls.

In addition, the method of heating the polymer component of the first single yarn in the step (C) of the first embodiment (hereinafter also simply referred to as the “heating method”) is to heat the roll of the roll portion, A method of heating the polymer component of the first single yarn may also be used.
In addition, the roll portion has a container for containing the roll and a liquid (such as water) that is contained together with the roll in the container, and the heating method heats the liquid to produce the first single yarn. may be a method of heating the polymer component. In the step (C), for example, drawing in a bath may be performed.
Furthermore, even if the heating method is a method of heating the polymer component of the first single yarn by blowing a heated gas (e.g., air, etc.) onto the roll portion or near the roll portion. good.
Moreover, you may use these heating methods together.

The draw ratio in the step (C) is 1.5 times or more, preferably 1.7 times or more. The draw ratio in the step (C) is, for example, 20 times or less.
When the draw ratio in the step (C) is 1.5 times or more, the orientation of the polymer component of the first single yarn in the drawing multifilament 100B is further enhanced.
The draw ratio in the step (C) can be determined by the following formula.
Stretch ratio in the step (C) = stretching roll section (m/min) / speed (m /min)

In the step (C), the relaxation rate calculated by the following formula is preferably 1 to 30%, more preferably 1 to 15%.
Relaxation rate (%) = ((speed of the drawing roll section 114 - speed of the winding roll section ("second winding roll section 116" in the first embodiment) for winding the drawing multifilament)) / speed of the winding roll part winding the multifilament for drawing) × 100

The speed (m/min) of the drawing roll section is the length per unit time of the drawing multifilament conveyed by the drawing roll section.
Although only one stretching roll unit is used in the first embodiment, a plurality of stretching roll units may be used. When a plurality of stretching roll units are used, the highest speed among the plurality is defined as "stretch roll unit speed".
The speed (m/min) of the take-up roll used in the step (C) is the length per unit time of the drawing multifilament conveyed by the take-up roll.
The speed (m/min) of the winding roll part for winding the multifilament for drawing is the length per unit time of the multifilament for drawing wound on the winding roll part.

In the step (C), a multifilament may be obtained by drawing only one drawing multifilament, or a plurality of drawing multifilaments may be combined, and a plurality of combined threads may be obtained. A multifilament may be obtained by drawing a drawing multifilament.

(Second Embodiment: Spindraw Method)
Next, a second embodiment will be described with reference to FIG.
Note that explanations that overlap with those of the first embodiment will be omitted, and those that are not specifically explained in the second embodiment will be the same as those explained in the first embodiment.

A method for producing a multifilament according to the second embodiment is a method for producing a drawing multifilament and a multifilament by a spin-draw method.
The spin-draw method is a method in which a step of obtaining a plurality of molten raw yarns by discharging a melt from a plurality of discharge holes and a step of drawing a multifilament for drawing by a drawing roll unit are carried out in one step. be. The spin-draw method is also called the “SDY method” or the “direct spinning drawing method”.

In the second embodiment, in the step (B), a gas of 0° C. or more and 50° C. or less is blown to the 30 or more raw yarns 100A in a molten state to cool the 30 or more raw yarns 100A. The multifilament for drawing 200B is obtained, and the multifilament for drawing 200B obtained in the step (B) is taken up by the take-up roll section 207 .
Next, in the step (C), the drawing multifilament 200B taken by the take-up roll part 207 is passed through three drawing roll parts (first drawing roll part 208, second drawing roll part 209, and third drawing roll part 209). is stretched by the stretching roll unit 210).
Then, in the step (C), the multifilament is obtained by winding the drawn multifilament 200B with the take-up roll unit 212 .
The winding roll section 212 has a bobbin. A bobbin is a concept that also includes a paper tube. The bobbin may or may not have a collar.
Specifically, in the step (C), the multifilament is obtained by winding the drawn multifilament 200B on the bobbin of the winding roll section 212 .
In the step (C) in FIG. 3, the drawing multifilament 200B drawn by the drawing roll section is wound by the winding roll section 212 to obtain a multifilament. A multifilament may be obtained without winding 200B by the winding roll part 212 .
Further, in the step (C), the drawing multifilament 200B drawn by the drawing roll section may be transported by the take-off roll section 211 .

In the step (B), the drawing multifilament 200B is obtained by cooling the 30 or more raw yarns 100A in the first cooling box 105, and in the step (C), the drawing multifilament 200B is taken. The roll unit 207 picks up the sheet.
The drawing multifilament 200B may be obtained by cooling the 30 or more raw yarns 100A cooled in the first cooling box 105 in the second cooling box .
Although the take-up roll unit 207 is composed of two rolls in FIG. 1, it may be composed of one roll, or may be composed of three or more rolls.

In the second embodiment, each stretching roll section may also serve as the heat treatment roll section.
Each stretching

roll section

208, 209, 210 (each heat

treatment roll section

208, 209, 210) is composed of two rolls in FIG. It may consist of rolls.
From the viewpoint of promoting the crystallization of the polymer component contained in the first single yarn in the drawing multifilament 200B or improving the heat resistance of the polymer component contained in the first single yarn, the heat treatment roll portion The temperature is preferably 30-100°C, more preferably 40-90°C.
When the temperature of the environment in which the step (C) is performed is 30°C or higher, the crystallization of the polymer component contained in the first single yarn can be promoted without using the heat treatment roll unit. .

In this embodiment, the spin draft number (NDR) is preferably 50 or higher, more preferably 80 or higher. Also, the NDR is usually 5000 or less.
NDR can be calculated by the following formula.
NDR = Speed (m/min) of the take-up roll section (first take-up roll section) that first takes the yarn from the spinning nozzle/spinning nozzle flow rate (m/min)
When the NDR is 50 or more, the orientation of the polymer component contained in the first single yarn in the drawing multifilaments 100B and 200B can be enhanced, and as a result, the strength of the multifilament can be further enhanced. .
In addition, in the first embodiment (sequential drawing method), the first take-off roll unit is the first take-off roll unit 107 that takes over 30 or more of the raw yarns 100A.
Further, in the second embodiment (spin-draw method), the first take-up roll unit is the take-up roll unit 207 that takes over the drawing multifilament 200B.

<Manufacturing method of staple>
The staple manufacturing method according to the present embodiment obtains the multifilament by the multifilament manufacturing method according to the present embodiment.
In the staple manufacturing method according to the present embodiment, a staple having a length of 20 cm or less is obtained by cutting the multifilament.
A staple having a length of 20 cm or less may be obtained by doubling a plurality of multifilaments and cutting the doubling of the plurality of multifilaments.

In the staple manufacturing method according to the present embodiment, the multifilament may be crimped, and the crimped multifilament may be cut to obtain a staple as a crimped yarn (crimped yarn).
Further, in the aspect of obtaining the multifilament by winding the drawn multifilament for drawing by the winding

rolls

116 and 212 in the step (C), the drawn multifilament for drawing is wound by the winding

rolls

116 and 212. A crimped multifilament may be obtained by crimping the drawn multifilament for drawing before winding.

That is, after obtaining a multifilament by winding the drawn multifilament for drawing on the winding rolls 116 and 212 (specifically, the bobbins (paper tubes, etc.) of the winding rolls 116 and 212), the multifilament The filaments may be crimped.
Alternatively, the multifilament obtained without using the winding roll may be crimped.
Furthermore, the multifilament for drawing which is drawn during transfer from the take-off rolls 115 and 211 to the take-up rolls 116 and 212 may be crimped.

Crimp processing is not particularly limited, but can be performed by a known crimp processing method (for example, gear crimp method, stuffing box method, etc.).
The crimping process causes the staple to have crimps (specifically mechanical crimps).
If necessary, a preheating step of preheating the yarn to be crimped may be performed before crimping the yarn to be crimped (multifilament or drawn multifilament for drawing).
In the preheating step, the surface temperature of the yarn to be crimped is measured, and appropriate conditions are determined in consideration of the degree of orientation, degree of crystallinity, strength, heat resistance, and the like. The surface temperature is generally 40 to 140°C, preferably 40 to 120°C, more preferably 50 to 120°C. When the surface temperature is 40° C. or higher, mechanical properties suitable for crimping can be obtained. When the temperature is 140° C. or lower, drawdown can be suppressed, and process stability of crimping can be improved. The preheating step may be, for example, wet heat treatment or dry heat treatment. Steam, for example, can be used in the wet heat treatment. For the dry heat treatment, for example, a hot air oven, an electric heater, or the like can be used.

When the yarn to be crimped is preheated so that the surface temperature of the yarn to be crimped is 40 to 140° C. and then crimped into a multifilament by the stuffing box method, the stuffing box pressure is 0.5°C. It is preferable to crimp the multifilament under conditions of 001 to 0.1 MPa. The stuffing box pressure is more preferably 0.001 to 0.08 MPa, still more preferably 0.001 to 0.06 MPa, even more preferably 0.001 to 0.04 MPa.

Since this embodiment is configured as described above, it has the following advantages.

That is, the drawing multifilament according to the present embodiment has 30 or more first single yarns.
The first single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average fineness of the first single yarn is 30 dtex or less.
The variation coefficient of fineness of the first single yarn is 33% or less.

Since the variation coefficient of fineness of the first single yarn in the drawing multifilament according to the present embodiment is as small as 33% or less, the drawing multifilament according to the present embodiment includes the extremely thin second single yarn. it gets harder. As a result, when the drawing multifilament according to the present embodiment is drawn to obtain a multifilament, the first single yarn is cut even if the average fineness of the second single yarn is reduced and the draw ratio is increased. becomes difficult.
In addition, by increasing the draw ratio when obtaining the multifilament by drawing the drawing multifilament according to the present embodiment, the orientation of the poly(3-hydroxyalkanoate) resin in the multifilament is increased, and as a result, The strength of the obtained multifilament is increased.
Therefore, according to the multifilament for drawing according to the present embodiment, it becomes easy to obtain a multifilament with high strength even if the average value of the fineness of the second single yarn is small.

Moreover, the multifilament according to the present embodiment is a drawn multifilament.
The multifilament according to this embodiment has 30 or more second single yarns.
The second single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average fineness of the second single yarn is 20 dtex or less.
The variation coefficient of fineness of the second single yarn is 33% or less.

Since the coefficient of variation of the fineness of the second single yarn in the multifilament according to the present embodiment is 33% or less, the coefficient of variation of the fineness of the first single yarn in the drawing multifilament used to produce the multifilament is small.
Further, when the coefficient of variation of the fineness of the first single yarn in the drawing multifilament is small, the drawing multifilament is less likely to contain the extremely thin second single yarn. As a result, when the drawing multifilament is drawn to obtain the multifilament, the single yarn is difficult to cut even if the draw ratio is increased to reduce the average fineness of the second single yarn.
In addition, by increasing the draw ratio when obtaining the multifilament by drawing the multifilament for drawing, the orientation of the poly(3-hydroxyalkanoate) resin in the multifilament is increased, and as a result, the resulting multifilament. Increases strength.
Therefore, the multifilament according to the present embodiment is a multifilament that can easily increase the strength even if the average fineness of the second single yarn is small.

Furthermore, the method for producing a multifilament for drawing according to the present embodiment is a method for obtaining a multifilament for drawing by a melt spinning method.
In the method for producing a drawing multifilament according to the present embodiment, a spinning nozzle having 30 or more discharge holes is used to discharge the melt by the melt spinning method, thereby producing 30 or more molten raw yarns. A step (A) of obtaining, and a step of obtaining a drawing multifilament by blowing a gas of 0° C. or more and 50° C. or less to 30 or more of the raw yarns in a molten state to cool the 30 or more yarns ( B).
The melt contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent.
The average value of the fineness of the first single yarn in the drawing multifilament is 30 dtex or less,
In the step (B), the heat transfer coefficient between the 30 or more molten filaments and the gas is set to 60 W/(m ² ·K) or more.

In the step (B), a gas of 0° C. or more and 50° C. or less is blown to the 30 or more molten raw yarns to cool the 30 or more raw yarns, and the 30 or more molten raw yarns are cooled. By setting the heat transfer coefficient between and the gas to 60 W/(m ² K) or more, the time in which the poly(3-hydroxyalkanoate) resin crystallizes is within the appropriate range. can be adjusted, and the progress of crystallization of the poly(3-hydroxyalkanoate)-based resin can be optimized. Thereby, the drawability of the drawing multifilament can be optimized. Therefore, when the drawing multifilament is drawn to obtain the multifilament, it becomes difficult to cut the single filament even if the drawing ratio is increased.
In the step (B), the raw yarn is drawn to some extent by being taken up by the take-up roll portion, but the single yarn existing inside the raw yarn (hereinafter also referred to as "internal single yarn") and the outer single yarn are stretched. The existing single yarns (hereinafter also referred to as "outer single yarns") are cooled relatively uniformly with a gas of 0 ° C. or higher and 50 ° C. or lower, so that the inner single yarns and the outer single yarns are uniformly drawn. be. As a result, the variation coefficient of the fineness of the first single yarn in the drawing multifilament becomes small (for example, the variation coefficient becomes 33% or less). That is, it becomes difficult for the drawing multifilament to include extremely thin first single yarns. As a result, when the multifilament for drawing is drawn to obtain the multifilament, the first single yarn in the multifilament for drawing is difficult to cut even if the draw ratio is increased.
In addition, by increasing the draw ratio when obtaining the multifilament by drawing the multifilament for drawing, the orientation of the poly(3-hydroxyalkanoate) resin in the multifilament is increased, and as a result, the resulting multifilament. Increases strength.
Therefore, according to the method for producing a multifilament for drawing according to the present embodiment, it is possible to obtain a multifilament for drawing that makes it easy to produce a multifilament with high strength even if the average fineness of the second single yarn is small. can.

Further, the method for producing a multifilament according to the present embodiment obtains the multifilament for drawing by the method for producing a multifilament for drawing according to the present embodiment.
Further, the method for producing a multifilament according to the present embodiment has a step (C) of obtaining a multifilament by drawing the drawing multifilament by a factor of 1.5 or more with a draw roll unit.

In the method for producing a multifilament according to the present embodiment, the multifilament for drawing is obtained by the method for producing a multifilament for drawing according to the present embodiment, and in the step (C), the multifilament for drawing is passed through the drawing roll unit. By drawing a multifilament by a factor of 5 or more, it is possible to obtain a multifilament having a high strength even if the average fineness of the second single yarn is small.

Furthermore, in the method for producing a multifilament according to the present embodiment, in the step (B), a gas of 0 ° C. or higher and 50 ° C. The raw yarn is cooled to 50° C. or less to obtain the multifilament for drawing, and in the step (C), the multifilament for drawing is heated and drawn by the drawing roll section.

In the step (C), by drawing the drawing multifilament, the orientation of the poly(3-hydroxyalkanoate) resin contained in the drawing multifilament can be increased, thereby increasing the strength of the multifilament. can increase
Here, in order to enhance the orientation of the poly(3-hydroxyalkanoate)-based resin, it is desirable to stretch in a temperature range suitable for enhancing the orientation of the poly(3-hydroxyalkanoate)-based resin. When the drawing multifilament is drawn at a temperature higher than the temperature range, the poly(3-hydroxyalkanoate)-based resin is in a molten state, and as a result, the poly(3-hydroxyalkanoate)-based resin is melted even after drawing. This is because the orientation is not so high. In addition, if the drawing multifilament is to be drawn at a temperature lower than the temperature range, the poly(3-hydroxyalkanoate)-based resin will be too hard to draw the raw yarn, and the drawing multifilament will not be drawn. This is because if the drawing multifilament is forcibly pulled in an attempt to draw it, the drawing multifilament will break and the multifilament cannot be produced.
In the present embodiment, the 30 or more raw yarns are cooled to 50°C or lower by blowing a gas of 0°C or higher and 50°C or lower onto the 30 or more molten raw yarns in the step (B). to obtain the multifilament for drawing, and in the step (C), the multifilament for drawing is heated and drawn by the drawing roll unit, thereby performing the SDY method (spin draw method) (multifilament for drawing with ambient air Compared to the method of drawing while cooling), when drawing the drawing multifilament, the temperature range for drawing is suitable for increasing the orientation of the poly(3-hydroxyalkanoate)-based resin. It becomes easy to adjust the temperature of the multifilament, and as a result, it becomes easy to improve the orientation of the poly(3-hydroxyalkanoate) resin of the multifilament for drawing.
Therefore, in the present embodiment, it becomes easier to increase the strength of the multifilament.

The multifilament and staple according to this embodiment may be used as they are in the form of filaments.
Also, a textile product (fiber body) may be produced using the multifilament or staple according to the present embodiment.
The fiber product can be made into various shapes (for example, non-woven fabric, etc.).
The multifilament, staple, and fiber product according to the present embodiment can be suitably used for conventionally known applications.
Multifilaments, staples, and fiber products according to the present embodiment can be suitably used in fields such as agriculture (for example, gardening), fisheries, forestry, medical industry, and food industry.
Examples of the textile products include clothes, curtains, carpets, bags, shoes, wiping materials, sanitary products, automobile members, building materials, and filtering materials (filters).

[Disclosure items]
Each of the following items is a disclosure of a preferred embodiment.

[Item 1]
A drawing multifilament having 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 30 dtex or less,
A multifilament for drawing, wherein the single yarn has a fineness variation coefficient of 33% or less.

[Item 2]
The multifilament for drawing according to item 1, wherein the poly(3-hydroxyalkanoate)-based resin comprises a poly(3-hydroxybutyrate-based resin).

[Item 3]
A drawn multifilament,
The multifilament has 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 20 dtex or less,
The multifilament, wherein the coefficient of variation of the fineness of the single yarn is 33% or less.

[Item 4]
The multifilament according to item 3 is cut,
A staple having a length of 20 cm or less.

[Item 5]
A method for producing a multifilament for drawing, which obtains a multifilament for drawing by a melt spinning method,
A step (A) of obtaining 30 or more molten raw yarns by discharging the melt by the melt spinning method using a spinning nozzle having 30 or more discharge holes;
a step (B) of obtaining a drawing multifilament by blowing a gas of 0° C. or more and 50° C. or less onto 30 or more of the molten raw yarns to cool the 30 or more raw yarns;
The melt contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn in the drawing multifilament is 30 dtex or less,
In the step (B), the method for producing a multifilament for drawing, wherein the heat transfer coefficient between the 30 or more molten raw yarns and the gas is 60 W/(m ² ·K) or more.

[Item 6]
6. The method for producing a multifilament for drawing according to item 5, wherein in the step (B), the heat transfer coefficient is set to 125 W/(m ² ·K) or more.

[Item 7]
7. The method for producing a multifilament for drawing according to item 5 or 6, wherein in the step (B), the speed of the gas blown onto the 30 or more raw yarns is set to 0.3 m/s or more.

[Item 8]
The multifilament for drawing is obtained by the method for producing a multifilament for drawing according to any one of items 5 to 7,
A method for producing a multifilament, comprising a step (C) of obtaining a multifilament by drawing the drawing multifilament by a factor of 1.5 or more in a drawing roll unit.

[Item 9]
In the step (B), the 30 or more raw yarns in a molten state are cooled to 50°C or lower by blowing a gas of 0°C or higher and 50°C or lower to the 30 or more raw yarns for drawing. get multifilament,
9. The method for producing a multifilament according to item 8, wherein in the step (C), the drawing multifilament is heated and drawn by the drawing roll unit.

[Item 10]
Obtaining the multifilament by the method for producing a multifilament according to item 8 or 9,
A method for producing a staple, wherein a staple having a length of 20 cm or less is obtained by cutting the multifilament.

The present invention is not limited to the above embodiments. Moreover, the present invention is not limited by the above effects. Furthermore, the present invention can be modified in various ways without departing from the gist of the present invention.

For example, the multifilament for drawing according to the present embodiment is obtained by the manufacturing method described above, but the multifilament for drawing according to the present invention may be obtained, for example, as follows.
That is, 30 or more first single yarns are selected and collected so that the average fineness of the first single yarn is 30 dtex or less and the coefficient of variation of the fineness of the first single yarn is 33% or less. Thus, a drawing multifilament may be obtained.

Next, the present invention will be described more specifically with reference to examples and comparative examples. It should be noted that the present invention is by no means limited to these examples.

<Example 1>
A multifilament was produced by the method of the first embodiment (sequential drawing method).

(Step (A))
First, the following materials were dry-blended in the following proportions, and the dry-blended materials were melt-kneaded at 150° C. by an extruder to obtain pellets.
As a poly(3-hydroxyalkanoate) resin, (3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (ratio of 3-hydroxyhexanoate: 6 mol%, Mw: 350,000, melt Flow rate (MFR) (165° C., 5 kg): 12 g/10 min) (P3HB3HH): 100 parts by mass Pentaerythritol as a crystal nucleating agent (Neurizer-P, manufactured by Nippon Synthetic Chemical Co., Ltd.): 1.0 parts by mass Having an amide bond Erucamide as a lubricant: 0.5 parts by mass Behenic acid amide as a lubricant having an amide bond: 0.5 parts by mass The glass transition temperature of the pellet was 2°C. The crystallization temperature of the pellet was 100°C. The melting point of the pellet was 146°C. The pyrolysis temperature of the pellets was 180°C.

Then, as shown in FIG. 1, the pellets were melted by a kneading extruder 102 (single-screw extruder, screw diameter: 25 mm) to obtain a melt.
Then, the melt is discharged from a spinning nozzle 104 (temperature: 175° C., number of discharge holes: 368, shape of discharge holes: circular, diameter of discharge holes: 0.3 mm) to produce 368 raw yarns 100A. I really got it.
The melt flow rate was adjusted to 5.6 kg/h by the gear pump 103 .

(Step (B))
Air at 20° C. was blown to the 368 raw yarns 100A in a cooling box 105 at a speed of 0.7 m/s by a circular quench method.
When the heat transfer coefficient between the 368 molten yarns 100A and the air is obtained by the method described above from the temperature of the air, the speed of the air, and the diameter of the discharge hole, the heat transfer coefficient is , 194 W/(m ² ·K). Also, in the cooling box 106, no gas was blown.
Next, the 368 raw yarns 100A cooled by the cooling

boxes

105 and 106 are taken up by the first take-up roll unit 107 (448 m/min), and the 368 raw yarns 100A are transferred to the first transport roll unit 108 (471 m /min), second transport roll unit 109 (471 m/min, 70° C.), third transport roll unit 110 (471 m/min), and fourth transport roll unit 111 (471 m/min). , 368 raw yarns 100A were wound on the first winding roll unit (461 m/min) and stored at room temperature (5 to 35° C.) for 18 hours to obtain a drawing multifilament.

(Step (C))
As shown in FIG. 2, the drawing multifilament is taken from the first take-up roll 112 by the second take-up roll 113 (4.8 m/min, 30° C.), and the drawing roll 114 (11.5 m/min. min, 25° C.), transported by a take-off roll unit (heat treatment roll unit) 115 (10.4 m/min, 90° C.), and wound by a second winding roll unit 116 (10.4 m/min). Thus, a multifilament was obtained.
The draw ratio was 2.4 times.
In the multifilament, the second single yarn was not broken. Also, no fusion between the second single yarns was observed.
For these reasons, the appearance of the multifilament was good.

As the take-up roll part and the transport roll part, a roll part composed of two rolls each having the same speed and the same temperature was used.

Using the obtained multifilaments, staples were produced as follows.
First, in order to obtain a staple having an appropriate fineness, a plurality of obtained multifilaments were combined.
Next, the plied multifilament was preheated with steam so that the surface temperature of the plied multiple multifilaments was 65°C.
Then, a plurality of preheated multifilaments are supplied to a stuffing box at a conveying speed of 30 m/min, and the plurality of multifilaments are crimped under the conditions of a nip pressure of 0.20 MPa and a stuffing pressure of 0.03 MPa. A crimped yarn was obtained.
Next, the crimped yarn was cut with a toe cutter so that the staple had a length of 51 mm, thereby obtaining a crimped staple. The number of crimps of the staple was 14/25 mm.

<Examples 2 to 7>
A drawing multifilament, a multifilament, and a staple were obtained in the same manner as in Example 1, except that the conditions of steps (A) to (C) were changed to those shown in Table 2 below.
Also in Examples 2 to 7, the number of crimps of the staple was 14/25 mm.

<Comparative Examples 1 and 5>
A drawing multifilament and a multifilament were obtained in the same manner as in Example 1, except that the conditions of steps (A) to (C) were changed to those shown in Table 2 below.

<Comparative Example 2>
A multifilament for drawing was obtained in the same manner as in Example 1, except that the conditions in steps (A) and (C) were changed to those shown in Table 2 below.
Then, an attempt was made to obtain a multifilament in the same manner as in Example 1, except that the drawing multifilament was used and the conditions in step (C) were changed to those shown in Table 2 below. , a part of the first single yarn was broken, and a multifilament could not be produced.

<Comparative Examples 3 and 4>
An attempt was made to obtain a drawing multifilament in the same manner as in Example 1, except that the conditions of steps (A) and (B) were changed to those shown in Table 2 below.
However, in Comparative Example 3, the adjacent first single yarns were fused together, and a drawing multifilament could not be obtained.
Further, in Comparative Example 4, part of the raw yarn was broken between the spinning nozzle 104 and the first winding roll portion 112, and the multifilament for drawing could not be obtained.

<Average fineness and coefficient of variation of the first single yarn in the drawing multifilament>
The average value of the fineness of the first single yarn in the drawing multifilament and the coefficient of variation were obtained by the methods described above.
Table 2 below shows the average value of the fineness of the first single yarn in the multifilament for drawing and the coefficient of variation.

<Average fineness of second single yarn in multifilament and coefficient of variation>
The average value of the fineness of the second single yarn in the multifilament and the coefficient of variation were determined by the methods described above.
Table 2 below shows the average value of the fineness of the second single yarn in the multifilament and the coefficient of variation.

<Average Tensile Strength of Second Single Yarn in Multifilament>
The average tensile strength of the second single yarn in the multifilament was obtained by the method described above.
Table 2 below shows the average tensile strength of the second single yarn in the multifilament.

As shown in Table 2, in Examples 1 to 7 within the scope of the present invention, the coefficient of variation of the fineness of the first single yarn in the drawing multifilament is 38.1% or more Comparative Examples 1 and 5 Compared to , the tensile strength of the second single yarn in the multifilament was higher.
In addition, in Comparative Example 2 in which a drawing multifilament having a coefficient of variation of the fineness of the first single yarn of 38.1% was used and an attempt was made to obtain a multifilament at the same draw ratio as in Example 3, the multifilament was I couldn't get it.
Therefore, according to the present invention, it is possible to provide a multifilament for drawing from which it is easy to obtain a multifilament with high strength even if the average single yarn fineness is small.

Further, as shown in Table 2, in Examples 1 to 7 within the scope of the present invention, compared to Comparative Examples 1 and 5 in which the heat transfer coefficient is 45 W / (m ² · K) or less, The coefficient of variation of the fineness of the first single yarn in the multifilament was small.
In Comparative Example 3 in which no air was blown (the air velocity was 0.0 m/s) and Comparative Example 4 in which the air temperature was 60° C., a drawing multifilament could not be obtained.

100A: raw yarn, 100B: drawing multifilament, 101: material input unit, 102: kneading extruder, 103: gear pump, 104: spinning nozzle, 105: first cooling box, 106: second cooling box, 107 : first take-up roll part, 108: first transport roll part, 109: second transport roll part, 110: third transport roll part, 111: fourth transport roll part, 112: first roll Take-up roll part 113: Second take-up roll part 114: Stretching roll part (heat-treated roll part) 115: Take-off roll part (heat-treated roll part) 116: Second take-up roll part
200B: Multifilament for drawing, 207: Take-up roll part, 208: First drawing roll part (heat treatment roll part), 209: Second drawing roll part (heat treatment roll part), 210: Third drawing roll part ( heat treatment roll section), 211: take-off roll section, 212: winding roll section

Claims

A drawing multifilament having 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 30 dtex or less,
A multifilament for drawing, wherein the single yarn has a fineness variation coefficient of 33% or less.
The drawing multifilament according to claim 1, wherein the poly(3-hydroxyalkanoate)-based resin contains a poly(3-hydroxybutyrate-based resin).
A drawn multifilament,
The multifilament has 30 or more single yarns,
The single yarn contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn is 20 dtex or less,
The multifilament, wherein the coefficient of variation of the fineness of the single yarn is 33% or less.
The multifilament according to claim 3 is cut,
A staple having a length of 20 cm or less.
A method for producing a multifilament for drawing, which obtains a multifilament for drawing by a melt spinning method,
A step (A) of obtaining 30 or more raw yarns in a molten state by discharging the melt by the melt spinning method using a spinning nozzle having 30 or more discharge holes;
a step (B) of obtaining a drawing multifilament by blowing a gas of 0° C. or more and 50° C. or less to the 30 or more molten raw yarns to cool the 30 or more raw yarns;
The melt contains a poly(3-hydroxyalkanoate)-based resin and a crystal nucleating agent,
The average value of the fineness of the single yarn in the drawing multifilament is 30 dtex or less,
In the step (B), the method for producing a multifilament for drawing, wherein the heat transfer coefficient between the 30 or more molten raw yarns and the gas is 60 W/(m 2 ·K) or more.
The method for producing a multifilament for drawing according to claim 5, wherein in the step (B), the heat transfer coefficient is set to 125 W/(m 2 ·K) or more.
The method for producing a multifilament for drawing according to claim 5 or 6, wherein in the step (B), the speed of the gas blown onto the 30 or more raw yarns is set to 0.1 m/s or more.
The drawing multifilament is obtained by the drawing multifilament manufacturing method according to claim 5 or 6,
A method for producing a multifilament, comprising a step (C) of obtaining a multifilament by drawing the drawing multifilament by a factor of 1.5 or more in a drawing roll unit.
In the step (B), the 30 or more raw yarns in a molten state are cooled to 50°C or lower by blowing a gas of 0°C or higher and 50°C or lower to the 30 or more raw yarns for drawing. get multifilament,
The method for producing a multifilament according to claim 8, wherein in the step (C), the drawing multifilament is heated and drawn by the drawing roll unit.
Obtaining the multifilament by the method for producing a multifilament according to claim 8,
A method for producing a staple, wherein a staple having a length of 20 cm or less is obtained by cutting the multifilament.