阅读说明：本技术 聚缩醛纤维的制造方法 (Method for producing polyacetal fiber ) 是由 伊东显 须长大辅 三上素直 于 2018-06-08 设计创作，主要内容包括：本发明提供一种白度不匀得到改善的聚缩醛纤维的制造方法。根据一个实施方式,提供一种聚缩醛纤维的制造方法,其使用190℃时荷重2.16kg下的熔体流动速率为5～60g/10分钟的氧亚甲基共聚物,得到聚缩醛纤维,该制造方法包括：从纺丝机的排出口牵拉上述聚缩醛纤维的牵拉工序；和将牵拉后的上述聚缩醛纤维拉伸的拉伸工序,上述牵拉工序后的聚缩醛纤维的拉伸伸长率E1为20～500％、且上述拉伸工序后的聚缩醛纤维的拉伸伸长率E2为10～100％,E1≥E2,并且,上述拉伸工序后的聚缩醛纤维的单纤维粗度为0.7～5.0旦尼尔。(The invention provides a method for producing a polyacetal fiber with improved whiteness unevenness. According to one embodiment, there is provided a method for producing a polyacetal fiber using an oxymethylene copolymer having a melt flow rate of 5 to 60g/10 min under a load of 2.16kg at 190 ℃, the method comprising: a drawing step of drawing the polyacetal fiber from a discharge port of a spinning machine; and a drawing step of drawing the drawn polyacetal fiber, wherein the drawn polyacetal fiber has a tensile elongation E1 of 20 to 500%, the drawn polyacetal fiber has a tensile elongation E2 of 10 to 100%, E1 is not less than E2, and the polyacetal fiber has a single fiber thickness of 0.7 to 5.0 denier.)

1. A method for producing a polyacetal fiber, characterized in that,

using an oxymethylene copolymer having a melt flow rate of 5 to 60g/10 min under a load of 2.16kg at 190 ℃ to obtain a polyacetal fiber,

the manufacturing method comprises the following steps:

a drawing step of drawing the polyacetal fiber from a discharge port of a spinning machine; and

a drawing step of drawing the drawn polyacetal fibers,

a tensile elongation E1 of the polyacetal fiber after the drawing step of 20 to 500%, and a tensile elongation E2 of the polyacetal fiber after the drawing step of 10 to 100%,

E1≥E2，

and the single fiber thickness of the polyacetal fiber after the drawing step is 0.7 to 5.0 deniers.

2. The manufacturing method according to claim 1,

the semicrystallization time of the oxymethylene copolymer is 5 to 500 seconds.

3. The manufacturing method according to claim 1 or 2,

the oxymethylene copolymer has an oxymethylene unit and an oxyethylene unit, and the content of the oxyethylene unit is 0.5 to 7.0 mol relative to 100 mol of the oxymethylene unit.

4. The production method according to any one of claims 1 to 3,

the stretching ratio in the stretching step satisfies the following formula (A):

110 is less than or equal to (100+ E1)/the stretching ratio is less than or equal to 200.

5. The production method according to any one of claims 1 to 4,

in the stretching step, stretching is performed in 2 stages using a pre-stretching roll and 2 or more stretching rolls,

the drawn polyacetal fiber in the 1 st stage of the drawing step has a tensile elongation E3 of 10 to 150%, and E1 is not less than E3 is not less than E2.

6. The production method according to any one of claims 1 to 5,

the stretching step is performed using a pre-stretching roll and 2 or more stretching rolls,

in the stretching step, the polyacetal fibers pass through the 2 or more stretching rollers after passing through the pre-stretching roller, and the temperature of at least 1 roller of the 2 or more stretching rollers is 3 to 20 ℃ higher than that of the pre-stretching roller.

7. The manufacturing method according to claim 6,

in the stretching step, the temperature of the pre-stretching roller and the temperature of at least 1 roller of the 2 or more stretching rollers are 130 to 155 ℃.

8. The production method according to any one of claims 1 to 7,

the fineness unevenness (U%) of the polyacetal fibers after the drawing step is 0.5 to 9%.

9. The production method according to any one of claims 1 to 8,

the polyacetal fibers have a tensile elongation E2 of 10 to 50%.

Technical Field

The present invention relates to a method for producing polyacetal fibers.

Background

Polyacetal is a polymer having a polymer skeleton mainly composed of oxymethylene repeating units, and is used mainly as an injection molding material in a wide range of fields including automobiles and electric appliances because of its characteristics such as mechanical strength, chemical resistance and solvent resistance.

As methods for producing polyacetal fibers, a method for producing a fiber having high strength and high elastic modulus (patent document 1), a method for producing a high-strength fiber having heat resistance, abrasion resistance, and chemical resistance (patent document 2), and the like have been disclosed.

Disclosure of Invention

Technical problem to be solved by the invention

As described above, polyacetal is a resin material having excellent physical properties, but if a fiber is produced by a conventional method and spun, the color tone of the obtained polyacetal fiber may be imparted with whiteness. If there is such unevenness in the color tone of the fiber, there is a problem that the unevenness in the thickness of the fiber increases, or that the processability is unstable in the subsequent false twisting or knitting.

The present inventors have found that a polyacetal fiber is more likely to cause unevenness in whiteness than a general resin fiber such as a polyester fiber. Accordingly, an object of the present invention is to provide a method for producing a polyacetal fiber having improved unevenness in whiteness.

Means for solving the problems

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that the above-mentioned problems can be solved by a production method in which the tensile elongation of the polyacetal fiber after the drawing step, and the like are adjusted to fall within predetermined ranges, and have completed the present invention.

The present invention is described below, for example.

[1] A method for producing a polyacetal fiber, which comprises using an oxymethylene copolymer having a melt flow rate of 5 to 60g/10 min under a load of 2.16kg at 190 ℃ to obtain a polyacetal fiber,

the manufacturing method comprises the following steps:

a drawing step of drawing the polyacetal fiber from a discharge port of a spinning machine; and

a drawing step of drawing the drawn polyacetal fibers,

a tensile elongation E1 of the polyacetal fiber after the drawing step of 20 to 500%, and a tensile elongation E2 of the polyacetal fiber after the drawing step of 10 to 100%,

E1≥E2，

the polyacetal fibers after the drawing step have a single fiber thickness of 0.7 to 5.0 denier.

[2] The production process according to [1], wherein the semicrystallization time of the oxymethylene copolymer is 5 to 500 seconds.

[3] The production method according to [1] or [2], wherein the oxymethylene copolymer has oxymethylene units and oxyethylene units, and the content of the oxyethylene units is 0.5 to 7.0 mol per 100 mol of the oxymethylene units.

[4] The production method according to any one of [1] to [3], wherein the stretch ratio in the stretching step satisfies the following formula (A):

110 is less than or equal to (100+ E1)/the stretching ratio is less than or equal to 200.

[5] The production method according to any one of [1] to [4], wherein in the stretching step, stretching is performed in 2 stages using a pre-stretching roll and 2 or more stretching rolls,

the drawn polyacetal fiber in the 1 st stage of the drawing step has a tensile elongation E3 of 10 to 150%, and E1 is not less than E3 is not less than E2.

[6] The production method according to any one of [1] to [5], wherein the stretching step is performed using a pre-stretching roll and 2 or more stretching rolls,

in the stretching step, the polyacetal fiber passes through the 2 or more stretching rollers after passing through the pre-stretching roller, and the temperature of at least 1 roller of the 2 or more stretching rollers is higher than the temperature of the pre-stretching roller by 3 to 20 ℃.

[7] The production process according to [6], wherein in the stretching step, the temperature of the pre-stretching roll and the temperature of at least 1 roll of the 2 or more stretching rolls are 130 to 155 ℃.

[8] The production method according to any one of [1] to [7], wherein the unevenness (U%) in fineness of the polyacetal fibers after the drawing step is 0.5 to 9%.

[9] The production process according to any one of [1] to [8], wherein the polyacetal fibers have a tensile elongation E2 of 10 to 50%.

Effects of the invention

According to the present invention, a method for producing a polyacetal fiber with improved unevenness in whiteness can be provided.

Drawings

FIG. 1 is a schematic view of an apparatus for producing polyacetal fibers.

Detailed Description

The present invention will be described in detail below by way of examples of manufacturing examples and examples, but the present invention is not limited to the examples of manufacturing examples and examples, and can be modified to any method without largely departing from the scope of the present invention.

< method for producing polyacetal fiber >

The method for producing a polyacetal fiber of the present invention is a method for producing a polyacetal fiber using an oxymethylene copolymer having a melt flow rate of 5 to 60g/10 min under a load of 2.16kg at 190 ℃. The manufacturing method is characterized by comprising: a drawing step of drawing the polyacetal fiber from a discharge port of the spinning machine; and a drawing step of drawing the drawn polyacetal fiber, wherein the drawn polyacetal fiber has a tensile elongation E1 of 20 to 500%, the drawn polyacetal fiber has a tensile elongation E2 of 10 to 100%, E1 is not less than E2, and the drawn polyacetal fiber has a single fiber thickness of 0.7 to 5.0 denier.

As described above, the inventors of the present invention have found that the uneven whiteness can be improved by a production method in which the tensile elongation of the polyacetal fiber after the drawing step, and the like are adjusted to be within predetermined ranges. The present inventors have also found that, by a production method in which the type of polyacetal used as a raw material, the thickness of a single fiber of a polyacetal fiber after a drawing step, and the like are adjusted to fall within a predetermined range, transparency, spinnability (processing stability at spinning) and secondary processability of the obtained fiber can be improved in addition to unevenness in whiteness. Further, it was found that transparency, spinnability and 2-pass processability are further improved by performing the drawing step in 2 stages and appropriately setting the temperature of the drawing roll at the time of spinning.

One embodiment of the method for producing polyacetal fibers of the present invention will be described with reference to the schematic diagram of fig. 1. In one embodiment of the present invention, the polyacetal fibers are produced by drawing a plurality of discharged fibrous materials (filaments) from a discharge port of a spinning machine by a drawing roll to form fibers, and further drawing the fibers by using a pre-drawing roll and a drawing roll. If necessary, the drawn fiber may be wound up by a take-up roll after the drawing step. Further, the drawing step and the stretching step are preferably continuous steps. The method for producing polyacetal fibers of the present invention can be used not only for the method of spinning multifilament as shown in fig. 1 but also for the method of spinning monofilament.

The structure of the spinning machine used in the production method of the present invention is not particularly limited, and any spinning machine may be used as long as it can melt the oxymethylene copolymer as a raw material and discharge the polyacetal fibers from the discharge port. If necessary, an extruder or the like may be provided, and the raw material oxymethylene copolymer is melt-kneaded in a spinning machine. Examples of the spinning machine include a general melt spinning device for a multifilament or a monofilament, which is composed of a single screw extruder, a gear pump, a screen, and a die. The barrel temperature of the extruder, the gear pump temperature, the number of holes of the discharge nozzle, and the like can be appropriately adjusted as needed. The fineness (fiber thickness) of the drawn fiber can be appropriately adjusted by the amount of raw material fed and the speed of the take-up roll.

The yarn discharged from the discharge port of the spinning machine was drawn into polyacetal fiber by a drawing roll, and then sent to a pre-drawing roll, and then drawn by 1 or more drawing rolls. By drawing, the tensile strength of the fiber can be improved. In the present specification, the "pre-drawing roll" is a roll positioned between a drawing roll and a pulling roll, and generally, the fiber is not drawn between the pre-drawing roll and the pulling roll or is drawn slightly to ensure spinning stability. Further, the "stretching roll" is a roll disposed after the pre-stretching roll, and the fiber is stretched between the pre-stretching roll and the stretching roll and/or between a plurality of stretching rolls. In the method for producing polyacetal fibers of the present invention, at least 1 drawing roll, preferably 2 or more drawing rolls are used. It is preferable to use 2 or more stretching rollers because the polyacetal fiber can be stretched in multiple stages.

The tensile elongation E1 of the polyacetal fiber after the drawing step and the tensile elongation E2 of the polyacetal fiber after the drawing step can be adjusted by adjusting the drawing speed (m/min) of the drawing roll and/or the winding speed (m/min) of the winding roll. The polyacetal fiber after the drawing step has a tensile elongation E1 of 20 to 500%, preferably 50 to 400%, more preferably 100 to 300%, and the polyacetal fiber after the drawing step has a tensile elongation E2 of 10 to 100%, preferably 10 to 50%, more preferably 10 to 40%, and E1. gtoreq.E 2. The tensile elongation E1 of the polyacetal fiber after the drawing step and the tensile elongation E2 of the polyacetal fiber after the drawing step can be measured by fixing the fiber on a jig having a pitch of 120mm and drawing the fiber at a speed of 100m/min using a measuring instrument such as Autograph AGS-X-1 kN manufactured by Shimadzu corporation, for example.

The drawing speed (m/min) of the drawing roll and the winding speed (m/min) of the winding roll are not particularly limited as long as the above E1 and E2 are satisfied, and the drawing speed (m/min) of the drawing roll and the roll before drawing are, for example, preferably 300 to 6000m/min, and particularly preferably 400 to 3000 m/min. The winding speed (m/min) of the drawing roll and the winding roll is preferably 1000 to 6000m/min, and particularly preferably 2000 to 6000 m/min. Preferably, the rotation speed of the roll before stretching is substantially equal to the drawing speed of the drawing roll. The take-up speed of the take-up roll is not particularly limited as long as it is substantially equal to the rotational speed of the stretching roll, but the take-up speed is preferably 0.1 to 10% slower, preferably 0.3 to 5% slower, and more preferably 0.5 to 2% slower than the rotational speed of the stretching roll in view of shrinkage of the polyacetal fiber. In addition, a value obtained by dividing the speed difference between the roll before stretching and the stretching roll by the roll pitch is defined as a strain speed. The strain rate is one of the parameters showing a tensile state, and if it is too fast, it causes tensile fracture, and therefore, it is 0 to 10000(1/min), more preferably 2000 to 10000(1/min), and still more preferably 5000 to 9000 (1/min).

The stretching ratio in the stretching step is not particularly limited as long as the technical problem of the present invention can be solved, and preferably satisfies the following formula (a).

110 is less than or equal to (100+ E1)/the drawing magnification is less than or equal to 200 (A)

The formula (a) is derived from the formula (B) based on the condition that the final tensile elongation of the fiber is 10 to 100% after multiplying the elongation at the drawing time by a corresponding draw ratio.

10 ≦ [ { (100+ E1) - (100 × stretch magnification) }/(100 × stretch magnification) ] × 100 ≦ 100 · (B)

According to another preferred embodiment of the present invention, the stretch ratio in the stretching step satisfies the following formula (C).

110 is less than or equal to (100+ E1)/the drawing magnification is less than or equal to 150 (C)

In the present specification, the "draw ratio" is a value indicating how much the fiber before drawing is drawn in the drawing step, and can be calculated by dividing the rotational speed of the drawing roll by the rotational speed of the roll before drawing.

According to a preferred embodiment of the present invention, in the stretching step, stretching can be performed in multiple stages using a pre-stretching roll and 2 or more stretching rolls. By performing drawing in multiple stages, spinning stability and processability 2 times can be further improved. When drawing is performed in multiple stages, E2 represents the tensile elongation of the polyacetal fiber after all the drawing steps. According to a more preferable aspect of the present invention, in the stretching step, the stretching may be performed in 2 stages using a pre-stretching roll and 2 or more stretching rolls. In the case of drawing in 2 stages, the tensile elongation E1 of the polyacetal fiber after the drawing step is preferably 20 to 500%, more preferably 50 to 400%, and further preferably 100 to 300%, the tensile elongation E3 of the polyacetal fiber after the drawing in the 1 st stage of the drawing step is preferably 10 to 150%, more preferably 20 to 140%, and further preferably 30 to 120%, and the tensile elongation E2 of the polyacetal fiber after all the steps of the drawing step is preferably 10 to 100%, more preferably 10 to 50%, further preferably 10 to 40%, and further preferably E1/E3/E2. By performing such drawing in multiple stages, a polyacetal fiber having excellent unevenness of whiteness and further excellent spinning properties and secondary processability can be obtained.

According to a preferred embodiment of the present invention, the drawing step is performed using a pre-drawing roller and 2 or more drawing rollers, and in the drawing step, the polyacetal fiber passes through the 2 or more drawing rollers after passing through the pre-drawing roller, and the temperature of at least 1 roller of the 2 or more drawing rollers is 3 to 20 ℃ higher than the temperature of the pre-drawing roller, and more preferably 5 to 20 ℃ higher. In the configuration in which the drawing step is carried out using a pre-drawing roller and 2 or more drawing rollers, and the polyacetal fibers pass through the 2 or more drawing rollers after passing through the pre-drawing roller in the drawing step, the spinning stability is improved by adjusting the temperatures of the pre-drawing roller and the drawing rollers. According to a more preferred embodiment of the present invention, in the stretching step, the temperature of the pre-stretching roll and the temperature of at least 1 roll of the 2 or more stretching rolls are 130 to 155 ℃. By adjusting the temperatures of the pre-drawing roll and the drawing roll as described above, a polyacetal fiber having good spinning properties can be obtained.

The polyacetal fibers after the drawing step have a single fiber thickness of 0.7 to 5.0 denier, preferably 1.0 to 4.0 denier, and more preferably 1.2 to 3.0 denier. The single fiber thickness is defined by a value obtained by dividing the fineness (fiber thickness) of the drawn fiber (1 multifilament) by the number of holes of the discharge nozzle of the spinning machine. When the thickness of the single fiber is in the range of 0.7 to 5.0 denier, a polyacetal fiber which is less likely to be subjected to tensile breakage during spinning, has excellent spinnability, and has excellent secondary processability can be obtained.

< polyacetal fiber >

The polyacetal fiber of the present invention is a fiber of a polymer having an oxymethylene structure as a unit structure, and can be obtained by spinning an oxymethylene copolymer by the production method of the present invention. The polyacetal fibers of the present invention have excellent degree of unevenness in whiteness, and the fiber-forming body has a uniform white color with a transparent feeling. In a preferred embodiment of the present invention, the polyacetal fiber of the present invention is also excellent in spinning property and secondary processability. In the present specification, "spinnability" is an index indicating whether or not a fiber is broken during spinning and stopped, and whether or not the fiber can be stably obtained. "secondary processability" is an index for evaluating stability when a fiber after drawing is further processed (for example, drawn or dyed) by using the fluctuation width of a measurement value when the tensile elongation is measured. The references of the respective indices are specifically shown in the examples of the present specification.

In a preferred embodiment of the present invention, the fineness unevenness (U%) of the polyacetal fibers after the drawing step is 0.5 to 9.0%, more preferably 0.5 to 8.0, and particularly preferably 0.6 to 5.0. In the present specification, "fineness unevenness (U%)" is a percentage of average unevenness deviation, and can be measured, for example, by using a measuring instrument such as USTER TESTER 5 manufactured by USTER corporation in accordance with JIS L1095: 2016 (9.20 parts). In another preferred embodiment of the present invention, the draw ratio of the polyacetal fibers is 0.5 to 5.0 times, more preferably 1.0 to 4.0 times, and still more preferably 1.2 to 3.0 times.

The oxymethylene copolymer used in the production method of the present invention is not particularly limited as long as it has a melt flow rate of 5 to 60g/10 min under a load of 2.16kg at 190 ℃. The oxymethylene copolymer preferably has a melt flow rate of 5 to 50g/10 min, more preferably 7 to 40g/10 min, under the same conditions. The melt flow rate can be measured by a method according to ISO1133 using, for example, a melt index meter manufactured by Toyo Seiki Kabushiki Kaisha.

According to a preferred embodiment of the present invention, the semicrystallization time of the oxymethylene copolymer is 5 to 500 seconds, more preferably 10 to 300 seconds, and still more preferably 15 to 100 seconds. In the present specification, the semicrystallization time of the oxymethylene copolymer is the time required for isothermal holding at 150 ℃ until crystallization, and for example, a measurement instrument such as DiamondDSC manufactured by Perkin Elmer can be used in accordance with JIS K7121: 2012 for the assay.

The oxymethylene copolymers may be used alone, or a plurality of oxymethylene copolymers different in the kind and content of the monomer may be mixed and used. The oxymethylene copolymer has, in addition to an oxymethylene unit, an oxyalkylene unit represented by the following formula (1) in the molecule.

(in the formula, R₀And R₀' may be the same or different and is a hydrogen atom, an alkyl group, a phenyl group or an alkyl group interrupted by 1 or more ether bonds, and m is an integer of 2 to 6)

The alkyl group is an unsubstituted or substituted linear or branched alkyl group having 1 to 20 carbon atoms, preferably a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, decyl, dodecyl, and octadecyl groups.

As substituents, mention may be made of hydroxyl, amino, alkoxy, alkenyloxymethyl and halogen. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Examples of the alkenyloxymethyl group include an allyloxymethyl group and the like.

The phenyl group is an unsubstituted phenyl group, or a phenyl group substituted with an unsubstituted or substituted alkyl group, an unsubstituted or substituted aryl group, or a halogen. Examples of the aryl group include a phenyl group, a naphthyl group, and an anthryl group.

Examples of the alkyl group interrupted by 1 or more ether bonds include groups represented by the following formula (2).

－CH₂－O－(R₁－O)_p－R₂(2)

(in the formula, R₁Is alkylene, p represents an integer of 0 to 20, R₂Is a hydrogen atom, an alkyl group, a phenyl group or a glycidyl group, where each (R)₁-O) units which may be identical or different)

The alkylene group is a linear or branched alkylene group having 2 to 20 carbon atoms which is unsubstituted or substituted, and examples thereof include an ethylene group, a propylene group, a butylene group, and a 2-ethylhexyl group. As R₁The alkylene group of (1) is preferably an ethylene group or a propylene group.

Preferably R₀And R₀' both are hydrogen atoms.

Examples of the oxyalkylene unit represented by the formula (1) include an oxyethylene unit, an oxypropylene unit, an oxybutylene unit, an oxypentylene unit and an oxyhexylene unit, preferably an oxyethylene unit, an oxypropylene unit and an oxybutylene unit, and more preferably an oxyethylene unit.

The oxymethylene copolymer may further have a unit represented by the following formula (3).

－CH(CH₃)－CHR₃－ (3)

(in the formula, R₃Is a group represented by the following formula (4)

－O－(R₁－O)_p－R₄(4)

(in the formula, R₄Is hydrogen atom, alkyl, alkenyl, phenyl or phenylalkyl, R₁And p is as defined for formula (2)

The alkenyl group is a straight-chain or branched-chain unsubstituted or substituted alkenyl group having 2 to 20 carbon atoms, and examples thereof include a vinyl group, an allyl group and a 3-butenyl group.

Examples of the alkyl moiety and the phenyl moiety in the phenylalkyl group include the above-mentioned alkyl groups and phenyl groups. Examples of the phenylalkyl group include a benzyl group, a phenethyl group, a phenylbutyl group, a 2-methoxybenzyl group, a 4-methoxybenzyl group, and a 4- (allyloxymethyl) benzyl group.

In the present invention, when a crosslinked structure is present, the alkenyl group and the glycidyl group in the group represented by formula (2) or the alkenyl group in the group represented by formula (4) can become a crosslinking point in a further polymerization reaction, and a crosslinked structure is formed.

The method for producing the oxymethylene copolymer is not particularly limited, and examples thereof include the following methods: trioxane, which is a trimer of formaldehyde, and a comonomer are bulk polymerized using a cationic polymerization catalyst such as boron trifluoride, a perchlorate, or a heteropoly acid. Examples of comonomers include: cyclic ether with 2-8 carbon atoms such as ethylene oxide, 1, 3-dioxolane, 1,3, 5-trioxepane, 1,3, 6-trioxacyclooctane and the like; cyclic formal having 2 to 8 carbon atoms such as cyclic formal of ethylene glycol and cyclic formal of diethylene glycol. With these comonomers, R can be formed₀And R₀' an oxyalkylene unit represented by the formula (1) which is also a hydrogen atom.

In the present invention, the oxymethylene copolymer also includes a 2-membered copolymer and a multipolymer. Therefore, as the oxymethylene copolymer used in the production method of the present invention, the following can be widely used: an oxymethylene copolymer having an oxymethylene unit and an oxyalkylene unit used in the above formula (1); an oxymethylene copolymer comprising oxymethylene units, oxyalkylene units represented by the above formula (1) and units represented by the above formula (3); and oxymethylene copolymers further having a crosslinked structure. In the present invention, R₀And R₀The unit represented by the formula (1)' which is not simultaneously a hydrogen atom may be formed by copolymerizing a glycidyl ether compound and/or an epoxy compound, and the unit represented by the formula (3) may be formed by copolymerizing an allyl ether compound, for example.

The glycidyl ether and the epoxy compound are not particularly limited, and there may be mentioned: epichlorohydrin; alkyl glycidyl formals such as methyl glycidyl formal, ethyl glycidyl formal, propyl glycidyl formal and butyl glycidyl formal; diglycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, hexanediol diglycidyl ether, resorcinol diglycidyl ether, bisphenol a diglycidyl ether, hydroquinone diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutylene glycol diglycidyl ether; triglycidyl ethers such as glycerol triglycidyl ether and trimethylolpropane triglycidyl ether; tetraglycidyl ethers such as pentaerythritol tetraglycidyl ether.

As the allyl ether compound, there can be mentioned polyethylene glycol allyl ether, methoxypolyethylene glycol allyl ether, polyethylene glycol-polypropylene glycol allyl ether, butoxypolyethylene glycol-polypropylene glycol allyl ether, polypropylene glycol diallyl ether, phenylethyl allyl ether, phenylbutyl allyl ether, 4-methoxybenzyl allyl ether, 2-methoxybenzyl allyl ether and 1, 4-diallyloxymethylbenzene.

In a preferred embodiment of the present invention, the oxymethylene copolymer has oxymethylene units and oxyethylene units (including the oxyalkylene units represented by the above formula (1)), and the content of the oxyethylene units is 0.5 to 7.0 mol, more preferably 1.0 to 4.0 mol, and still more preferably 1.0 to 2.5 mol, based on 100 mol of the oxymethylene units. The content of the oxymethylene unit and the oxyethylene unit in the oxymethylene copolymer can be determined by a Nuclear Magnetic Resonance (NMR) method.

Examples of the chain transfer agent include carboxylic acids, carboxylic acid anhydrides, esters, amides, imides, phenols, and acetal compounds. Among them, phenol, 2, 6-dimethylphenol, dimethanol formal and polyacetal dimethoxy are preferable, and dimethanol formal is more preferable. As the solvent, there may be mentioned: aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as methylene chloride and dichloroethane. The chain transfer agent can be used alone or in the form of a solution dissolved in a solvent. When the chain transfer agent is dimethanol formal, the addition amount thereof is equal toFor trioxane, it is usually set to less than 2X 10^-1The range of wt%.

Examples of the oxymethylene copolymer include "Ipipal (registered trademark)," F20-03 "," Ipipal (registered trademark) and "F40-03" (manufactured by Mitsubishi engineering plastics Co., Ltd.) as commercially available products.

The oxymethylene copolymer can be added with known additives and/or fillers within a range not impairing the object of the present invention. Examples of the additives include a crystal nucleating agent, an antioxidant, a plasticizer, a delustering agent, a foaming agent, a lubricant, a mold release agent, an antistatic agent, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a deodorant, a flame retardant, a sliding agent, a fragrance, an antibacterial agent, and the like. Examples of the filler include glass fiber, talc, mica, calcium carbonate, and potassium titanate whisker. Pigments and dyes can also be added and processed to the desired shade. Further, the resin composition may be modified by adding a transesterification catalyst, various monomers, a coupling agent (for example, other polyfunctional isocyanate compounds or epoxy compounds, glycidyl compounds, diaryl carbonates, etc.), a terminal treating agent, other resins, wood flour, and a naturally occurring organic filler such as starch. The time for adding the above-mentioned additives, fillers and the like is not limited at all, and they may be added at the stage of obtaining the oxymethylene copolymer, or may be added to an extruder together with the oxymethylene copolymer at the time of producing the polyacetal fiber.

The polyacetal fiber obtained by the production method of the present invention is composed of a plurality of filaments. That is, the polyacetal fibers are formed by bundling a plurality of strands discharged from a plurality of discharge ports.