阅读说明：本技术 聚氨酯弹性纤维和其卷纱体 (Polyurethane elastic fiber and yarn package thereof ) 是由 后藤英之 佐藤均 山本太郎 于 2018-11-20 设计创作，主要内容包括：提供一种聚氨酯弹性纤维,其特征在于,其为属于复丝纱的聚氨酯弹性纤维,化合物A与化合物B缩合而成的酯或磷酸酯的含有率相对于该聚氨酯弹性纤维的重量为50ppm以上且5％以下,前述化合物A为碳数4以上且30以下的一元羧酸、碳数4以上且30以下的二元羧酸、碳数4以上且30以下的三元羧酸、或磷酸中的任一种,前述化合物B为碳数1以上且30以下的一元醇、分子量3000以下的二元醇、或分子量3000以下的三元醇中的任一种。(Disclosed is a polyurethane elastic fiber which is a multifilament yarn, wherein the content of an ester or phosphate ester obtained by condensing a compound (A) with a compound (B) is 50ppm or more and 5% or less relative to the weight of the polyurethane elastic fiber, the compound (A) is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or phosphoric acid, and the compound (B) is any one of a monohydric alcohol having 1 or more and 30 or less carbon atoms, a dihydric alcohol having a molecular weight of 3000 or less, or a trihydric alcohol having a molecular weight of 3000 or less.)

1. A polyurethane elastic fiber belonging to a multifilament yarn, characterized in that the content of an ester or phosphate ester obtained by condensing a compound A, which is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or phosphoric acid, and a compound B, which is any one of a monohydric alcohol having 1 or more and 30 or less carbon atoms, a dihydric alcohol having a molecular weight of 3000 or less, or a trihydric alcohol having a molecular weight of 3000 or less, are 50ppm or more and 5% or less, relative to the weight of the polyurethane elastic fiber.

2. The polyurethane elastic fiber according to claim 1, wherein a ratio of a maximum value to a minimum value of diameters of monofilaments constituting the polyurethane elastic fiber belonging to the multifilament yarn is 1.1 or more and 2.0 or less.

3. The polyurethane elastic fiber according to claim 1 or 2, wherein the flow-out initiation temperature of the polyurethane elastic fiber measured by a flow tester is 200 ℃ or more.

4. The polyurethane elastic fiber according to any one of claims 1 to 3, wherein the content of the ester or phosphate is 50ppm or more and 1.5% or less based on the weight of the polyurethane elastic fiber.

5. The polyurethane elastic fiber according to any one of claims 1 to 4, wherein the compound A is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, or a tricarboxylic acid having 4 or more and 30 or less carbon atoms.

6. The polyurethane elastic fiber according to any one of claims 1 to 5, wherein the compound A is any one of a dicarboxylic acid having 4 or more and 30 or less carbon atoms or a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or the compound B is any one of a diol having a molecular weight of 3000 or less or a triol having a molecular weight of 3000 or less.

7. The polyurethane elastic fiber according to any one of claims 1 to 6, wherein an ester or a phosphate ester obtained by condensation of the compound A and the compound B has an aromatic ring.

8. The polyurethane elastic fiber according to any one of claims 1 to 7, further comprising 0.01% or more and 5% or less of a urethane compound containing a tertiary amine or a urea compound containing a tertiary amine.

9. The polyurethane elastic fiber according to claim 8, wherein the urethane compound containing a tertiary amine is a urethane compound having a repeating unit represented by the following formula (1):

in the formula, R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-10 hydrocarbon group having a valence of 1 to 10。

10. The polyurethane elastic fiber according to claim 8, wherein the urethane compound containing a tertiary amine is a urethane compound having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):

in the formula, R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-valent hydrocarbon group of 1 to 10,

in the formula, R₅Is a C5-30 2-valent hydrocarbon group, and R₆Is a C1-10 2-valent hydrocarbon group or polyoxyalkylene group.

11. The polyurethane elastic fiber according to claim 8, wherein the urea compound containing a tertiary amine is a urea compound represented by the following formula (3):

in the formula, R₇And R₈Independently of each other, a C1-10 1-valent hydrocarbon group, and R₉Is a C5-30 2-valent hydrocarbon group.

12. The polyurethane elastic fiber according to any one of claims 8 to 11, wherein a content of the tertiary amine-containing urethane compound or the tertiary amine-containing urea compound is larger than a content of an ester or phosphate obtained by condensing the compound a and the compound B.

13. The polyurethane elastic fiber according to claim 12, wherein the content of the tertiary amine-containing urethane compound or tertiary amine-containing urea compound is 20 times or more and 150 times or less the content of an ester or phosphate ester obtained by condensing the compound a and the compound B.

14. A wound yarn body of the polyurethane elastic fiber according to any one of claims 1 to 13.

15. The yarn package according to claim 14, wherein the elongation of the polyurethane elastic fiber in the yarn package is 5% or less.

Technical Field

The present invention relates to a polyurethane elastic fiber and a yarn package thereof.

Background

Polyurethane elastic fibers have excellent elastic properties and are therefore used for various products requiring stretchability and conformability, such as inner liners, stockings, compression garments, diapers, and the like. The processing speed of polyurethane elastic fibers for producing these products has been increasing year by year, and polyurethane elastic fibers and yarn packages thereof that do not break during processing have been strongly desired.

The polyurethane elastic fiber has an appropriate fineness depending on the application, and is often produced as a multifilament yarn in which a plurality of filaments are bundled according to the fineness.

However, in the case of processing the polyurethane elastic fiber of the multifilament yarn, there are problems as follows: the monofilament is easily broken due to heat cutting in a process of applying heat, such as a dyeing process in processing into a fabric, a heat setting process, a process of applying a high-temperature adhesive in manufacturing a diaper, or the like, because the monofilament is fluffed during the running, or the filament is wound around a guide or the like due to a tension variation.

However, it is difficult to produce a polyurethane elastic fiber having both the filament which is less likely to loose wool, the tension fluctuation during traveling which is small, and the filament which is less likely to be cut under thermal conditions, and the effect of suppressing the breakage cannot be said to be sufficient.

For example, in the polyurethane elastic fiber described in patent document 1 below, the strength of the false twisting is adjusted to join the monofilaments together, so that the monofilaments are less likely to be fluffed, but the variation in tension during running is large, and the effect of suppressing the yarn breakage is insufficient.

In addition, in the polyurethane elastic fiber described in the following patent document 2, by reducing the molecular weight of a part of the polyurethane polymer, the monofilament can be made less likely to be fluffed, but there are the following problems: since the melting point of the polymer is also lowered, the heat resistance is not good, and breakage due to heat during processing is likely to occur.

Disclosure of Invention

Problems to be solved by the invention

In view of the above problems of the prior art, an object of the present invention is to provide: the monofilament is less likely to loose wool, has small tension variation during running, and is less likely to be cut even under hot conditions, thereby sufficiently suppressing the breakage during processing.

Means for solving the problems

The present inventors have intensively studied and repeatedly conducted experiments to solve the above problems, and as a result, unexpectedly found that: the present inventors have completed the present invention by solving the above problems by incorporating a predetermined amount of ester or phosphate ester in the polyurethane elastic fiber.

Namely, the present invention is as follows.

[1] A polyurethane elastic fiber belonging to a multifilament yarn, characterized in that the content of an ester or phosphate ester obtained by condensing a compound A with a compound B is 50ppm or more and 5% or less relative to the weight of the polyurethane elastic fiber, the compound A is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or phosphoric acid, and the compound B is any one of a monohydric alcohol having 1 or more and 30 or less carbon atoms, a dihydric alcohol having a molecular weight of 3000 or less, or a trihydric alcohol having a molecular weight of 3000 or less.

[2] The polyurethane elastic fiber according to the above [1], wherein a ratio of a maximum value to a minimum value of diameters of monofilaments constituting the polyurethane elastic fiber belonging to the multifilament yarn is 1.1 or more and 2.0 or less.

[3] The polyurethane elastic fiber according to the above [1] or [2], wherein an outflow starting temperature of the polyurethane elastic fiber measured by a flow tester is 200 ℃ or more.

[4] The polyurethane elastic fiber according to any one of the above [1] to [3], wherein a content of the ester or the phosphate ester is 50ppm or more and 1.5% or less with respect to a weight of the polyurethane elastic fiber.

[5] The polyurethane elastic fiber according to any one of the above [1] to [4], wherein the compound A is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, or a tricarboxylic acid having 4 or more and 30 or less carbon atoms.

[6] The polyurethane elastic fiber according to any one of the above [1] to [5], wherein the compound A is any one of a dicarboxylic acid having 4 or more and 30 or less carbon atoms or a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or the compound B is any one of a diol having a molecular weight of 3000 or less or a triol having a molecular weight of 3000 or less.

[7] The polyurethane elastic fiber according to any one of the above [1] to [6], wherein an ester or a phosphate ester obtained by condensation of the compound A and the compound B has an aromatic ring.

[8] The polyurethane elastic fiber according to any one of the above [1] to [7], further comprising 0.01% or more and 5% or less of a urethane containing a tertiary amine or a urea compound containing a tertiary amine.

[9] The polyurethane elastic fiber according to the above [8], wherein the urethane compound containing a tertiary amine is a urethane compound having a repeating unit represented by the following formula (1):

{ formula (II) wherein R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-10 hydrocarbon group. }.

[10] The polyurethane elastic fiber according to the above [8], wherein the urethane compound containing a tertiary amine is a urethane compound having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):

{ formula (II) wherein R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-10 hydrocarbon group. }

{ formula (II) wherein R₅Is a C5-30 2-valent hydrocarbon group, and R₆Is a C1-10 2-valent hydrocarbon group or polyoxyalkylene group. }.

[11] The polyurethane elastic fiber according to the above [8], wherein the urea compound containing a tertiary amine is a urea compound represented by the following formula (3):

{ formula (II) wherein R₇And R₈Independently of each other, is a C1-10 hydrocarbon group having a valence of 1 to 10, and R₉Is a C5-30 2-valent hydrocarbon group. }.

[12] The polyurethane elastic fiber according to any one of the above [8] to [11], wherein the content of the tertiary amine-containing urethane or tertiary amine-containing urea compound is larger than the content of an ester or phosphate obtained by condensation of the compound A and the compound B.

[13] The polyurethane elastic fiber according to the above [12], wherein the content of the tertiary amine-containing urethane or tertiary amine-containing urea compound is 20 times or more and 150 times or less the content of an ester or phosphate ester obtained by condensing the compound A and the compound B.

[14] A wound yarn body of the polyurethane elastic fiber according to any one of the above [1] to [13 ].

[15] The yarn package according to the above [14], wherein the elongation of the polyurethane elastic fiber in the yarn package is 5% or less.

ADVANTAGEOUS EFFECTS OF INVENTION

In the polyurethane elastic fiber of the present invention, a predetermined amount of a specific ester or phosphate is contained in the polyurethane elastic fiber, so that the monofilament is less likely to be fluffed, the tension fluctuation during running is small, the monofilament is less likely to be cut under a thermal condition, and the breakage during processing can be sufficiently suppressed.

Drawings

Fig. 1 is a schematic view of an apparatus for measuring tension variation during running of a polyurethane elastic fiber.

Fig. 2 is a schematic view of an apparatus for measuring antistatic property when polyurethane elastic fiber is running.

Detailed Description

Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiments, and can be implemented by being variously modified within the scope of the gist thereof.

The polyurethane elastic fiber of the present embodiment is a polyurethane elastic fiber belonging to a multifilament yarn including a plurality of monofilaments, wherein the content of an ester or phosphate ester obtained by condensing a compound a with a compound B is 50ppm or more and 5% or less relative to the weight of the polyurethane elastic fiber, wherein the compound a is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or phosphoric acid, and the compound B is any one of a monohydric alcohol having 1 or more and 30 or less carbon atoms, a dihydric alcohol having a molecular weight of 3000 or less, or a trihydric alcohol having a molecular weight of 3000 or less.

In the present embodiment, the polyurethane constituting the polyurethane elastic fiber is not particularly limited as long as it has a structure polymerized with diisocyanate, polymer polyol, diol, diamine, or the like, for example. The polymerization method is not particularly limited. The polyurethane may be, for example, a polyurethane (also referred to as "polyurethane urea") polymerized from a diisocyanate, a polymer polyol, a low molecular weight diamine as a chain extender, or the like, or a polyurethane (also referred to as "polyurethane urethane") polymerized from a diisocyanate, a polymer polyol, a low molecular weight diol as a chain extender, or the like. Diols and isocyanates having a functionality of 3 or more may be used as long as the desired effects are not impaired.

Examples of the diisocyanate include aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates. The aromatic diisocyanate is not limited to the following, and examples thereof include diphenylmethane diisocyanate (hereinafter also referred to as "MDI"), toluene diisocyanate, 1, 4-diisocyanate benzene, xylylene diisocyanate, and 2, 6-naphthalene diisocyanate. Examples of the alicyclic diisocyanate and aliphatic diisocyanate include methylene bis (cyclohexyl isocyanate) (hereinafter also referred to as "H12 MDI"), isophorone diisocyanate, methylcyclohexane 2, 4-diisocyanate, methylcyclohexane 2, 6-diisocyanate, cyclohexane 1, 4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, octahydro 1, 5-naphthalene diisocyanate, and the like. These diisocyanates may be used alone or in combination of 2 or more. In particular, the diisocyanate is preferably an aromatic diisocyanate, more preferably MDI, from the viewpoint of stretch recovery of the elastic yarn.

The polymer polyol is not limited to the following, and examples thereof include polymer diols such as polyether diols, polyester diols, polycarbonate diols, polyacrylic diols, polythio diols, and polyalkylene diols. From the viewpoint of hydrolysis resistance, the polymer polyol is preferably a polyether polyol, and more preferably a polyether diol.

Examples of the polyether polyol include: polyethylene oxide, polyethylene glycol derivatives, polypropylene glycol, polytetramethylene ether glycol (hereinafter, also referred to as "PTMG"), modified PTMG (hereinafter, also referred to as "PTXG") which is a copolymer of Tetrahydrofuran (THF) and neopentyl glycol, and diol which is a copolymer of THF and 3-methyl THF. These polyether polyols may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The number average molecular weight of the polymer diol is preferably 1000 or more and 8000 or less. By using the polymer diol in this range, an elastic fiber excellent in elongation, stretch recovery property, and heat resistance can be easily obtained. From the viewpoint of UV embrittlement, PTMG, PTXG, and a polyol obtained by blending them are preferable as the polyether polyol.

As the chain extender, at least 1 selected from the group consisting of low molecular weight diamines and low molecular weight diols is preferable. The chain extender may be a substance having both a hydroxyl group and an amino group in the molecule, such as ethanolamine.

Examples of the low-molecular-weight diamine used as the chain extender include, but are not limited to, hydrazine, ethylenediamine, 1, 2-propanediamine, 1, 3-propanediamine, 2-methyl-1, 5-pentanediamine, 1, 2-diaminobutane, 1, 3-diaminobutane, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane, 2-dimethyl-1, 3-diaminopropane, 1, 3-diamino-2, 2-dimethylbutane, 2, 4-diamino-1-methylcyclohexane, 1, 3-pentanediamine, 1, 3-cyclohexanediamine, bis (4-aminophenyl) phosphine oxide, hexamethylenediamine, 1, 3-cyclohexyldiamine, and the like, Hexahydro-m-phenylenediamine, 2-methylpentamethylene diamine, bis (4-aminophenyl) phosphine oxide, and the like. These low molecular weight diamines may be used alone in 1 kind, or in combination with 2 or more kinds. From the viewpoint of elastic yarn stretch recovery, the low molecular weight diamine is preferably a diamine having 2 to 5 carbon atoms, and more preferably ethylenediamine.

The low-molecular-weight diol is not limited to the following, and examples thereof include ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, bishydroxyethoxybenzene, bishydroxyethyl terephthalate, and 1-methyl-1, 2-ethanediol. These low molecular weight diols may be used alone in 1 kind, or in combination with 2 or more kinds.

The polymerization method of the polyurethane polymerized from the diisocyanate, the polymer polyol, the diol, the diamine, and the like as described above is not particularly limited, and may be a melt polymerization method or a solution polymerization method. In the case of the solution polymerization method, a polyurethane solution can be obtained by polymerizing raw materials such as diisocyanate, polymer polyol, diol and diamine in a solvent such as DMAc, DMF, DMSO and NMP. The reaction method in the case of polymerizing polyurethane is not particularly limited, and the following methods may be mentioned: a one-step method in which each raw material is put into a solvent and reacted at an appropriate temperature; a prepolymer method in which diisocyanate is reacted with polymer polyol to form a prepolymer, and then a chain extension reaction is performed with diol and diamine to synthesize polyurethane; and the like.

The polyurethane elastic fiber may contain, to the extent that the desired effects are not impaired: examples of the known organic or inorganic compound used for the polyurethane elastic fiber include polymers other than polyurethane, antioxidants, heat stabilizers, antistatic agents, light stabilizers, ultraviolet absorbers, gas discoloration inhibitors, dyes, activators, delustering agents, colorants, fillers, antiblocking agents, and lubricants.

The method for spinning the polyurethane elastic fiber is not particularly limited. Examples of the spinning method include the following methods: a method of dissolving polyurethane in a solvent and spinning the solution by a wet method or a dry method; a method of melting polyurethane by heating and spinning by a melt method.

The polyurethane elastic fiber of the present embodiment can be spun with a conventionally known method to allow an oil for polyurethane elastic fiber to adhere to the fiber from the outside. Examples of the method for adhering the oil agent include: a method using an oiling roller. The oil component used here is not limited to the following, and various materials such as silicone oils such as dimethyl silicone, polyether-modified silicone, and polyamino-modified silicone, mineral oils, mineral fine particles such as talc, silica, and colloidal alumina, higher fatty acid metal salt powders such as magnesium stearate and calcium stearate, and waxes which are solid at room temperature such as higher fatty acid carboxylic acids, higher aliphatic alcohols, and paraffin polyethylene may be used in combination.

In the present embodiment, by containing the ester or phosphate ester in an amount of 50ppm or more and 5% or less based on the weight of the polyurethane elastic fiber, the monofilament is less likely to be fluffed, the tension fluctuation during running is small, the monofilament is less likely to be cut under a thermal condition, and the effect of sufficiently suppressing the breakage during processing can be exhibited.

As described above, the ester or phosphate ester contained in the polyurethane elastic fiber according to the present embodiment is obtained by condensing the following compound a and the following compound B.

Compound a is: any of monocarboxylic acids having 4 to 30 carbon atoms, dicarboxylic acids having 4 to 30 carbon atoms, tricarboxylic acids having 4 to 30 carbon atoms, or phosphoric acid.

Compound B is: any one of monohydric alcohol having 1 to 30 carbon atoms, dihydric alcohol having 3000 molecular weight or less, or trihydric alcohol having 3000 molecular weight or less.

The ester or phosphate ester may be contained in a predetermined amount in the polyurethane elastic fiber, and the form of "containing" is not particularly limited, and may be added to the inside of the polyurethane polymer or may be contained together with a treatment agent such as an oil agent to adhere to the fiber surface. The method of adding to the inside of the polyurethane polymer is not particularly limited, and for example, there can be employed: a method using a static mixer, a method using stirring, a method using a homomixer, a method using a twin-screw extruder, and the like. The method of including the treatment agent such as an oil agent is also not particularly limited, and for example, the following can be adopted: the ester or phosphate ester is contained in the oil agent in advance, and the ester or phosphate ester is attached to the polyurethane elastic fiber together with the oil agent by various means such as a method using a oiling roller, a nozzle, or a spray.

The reason why the monofilament is less likely to be fluffed by adding the ester or the phosphoric acid to the polyurethane elastic fiber has not been elucidated, but the inventors have assumed that the monofilament is fluffy. Consider that: since the ester or phosphate ester has poor compatibility with the polyurethane polymer, it is likely to bleed out from the elastic fiber and to locally exist on the surface of the monofilament, regardless of the method of incorporation into the polyurethane elastic fiber. In this way, the similar structures of the ester or the ester group of the phosphoric acid ester locally present on the surface attract each other by intermolecular force, and the monofilament becomes less likely to be fluffed.

In the present embodiment, the compound a used as a raw material before the condensation reaction of the ester or the phosphate ester may be any of a monocarboxylic acid having 4 to 30 carbon atoms, a dicarboxylic acid having 4 to 30 carbon atoms, a tricarboxylic acid having 4 to 30 carbon atoms, or phosphoric acid. The compound a is a monocarboxylic acid having 4 to 30 carbon atoms, a dicarboxylic acid having 4 to 30 carbon atoms, a tricarboxylic acid having 4 to 30 carbon atoms, or phosphoric acid, whereby fuzzing of the monofilament can be suppressed. The monocarboxylic acid, the dicarboxylic acid, and the tricarboxylic acid are not particularly limited with respect to the presence or absence of a branch or a substituent. The term "optionally having a substituent" means that the compound A has only a structure of a monocarboxylic acid, a dicarboxylic acid or a tricarboxylic acid, and optionally has an optional bond or substituent, for example, a bond such as an ester bond, an amide bond, an ether bond, a thioether bond, a disulfide bond or a urethane bond, a group such as an epoxy group, a nitro group, a cyano group, a ketone group, a formyl group, an acetal group, a thioacetal group or a sulfonyl group, or the like. Examples of the monocarboxylic acid having 4 or more and 30 or less carbon atoms, the dicarboxylic acid having 4 or more and 30 or less carbon atoms, and the tricarboxylic acid having 4 or more and 30 or less carbon atoms include benzoic acid, phthalic acid, terephthalic acid, trimellitic acid, adipic acid, sebacic acid, azelaic acid, maleic acid, citric acid, lauric acid, myristic acid, stearic acid, oleic acid, epoxidized vegetable oil, and the like.

In the present embodiment, the compound B used as a raw material before the condensation reaction of the ester or phosphate ester may be any of a monohydric alcohol having 1 to 30 carbon atoms, a dihydric alcohol having 3000 molecular weight or less, or a trihydric alcohol having 3000 molecular weight or less. The compound B is a monohydric alcohol having 30 or less carbon atoms, a dihydric alcohol having 3000 or less molecular weight, or a trihydric alcohol having 3000 or less molecular weight, whereby fuzzing of the monofilament can be suppressed. Further, the presence or absence of a branch, a substituent, or the like is not particularly limited. The term "optionally having a substituent" means that the compound B may have a structure of a monohydric alcohol, a dihydric alcohol or a trihydric alcohol, and may have an optional bond or substituent, for example, a bond such as an ester bond, an amide bond, an ether bond, a thioether bond, a disulfide bond or a urethane bond, a group such as an epoxy group, a nitro group, a cyano group, a ketone group, a formyl group, an acetal group, a thioacetal group or a sulfonyl group. Examples of the compound B include monohydric alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-hexanol, 2-hexanol, 3-hexanol, cyclohexanol, 2-ethyl-1-hexanol, 1-nonanol, isodecanol, phenol, and benzyl alcohol, dihydric alcohols such as 1, 2-ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, 1, 6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol, and trihydric alcohols such as glycerol and 1,2, 4-butane trihydric alcohol.

In the present embodiment, from the viewpoint of more effectively suppressing fuzzing of monofilaments, the compound B is more preferably a monohydric alcohol having 15 or less carbon atoms, a dihydric alcohol having 1500 or less molecular weight, or a trihydric alcohol having 1500 or less molecular weight, more preferably a monohydric alcohol having 15 or less carbon atoms, a dihydric alcohol having 500 or less molecular weight, or a trihydric alcohol having 500 or less molecular weight, more preferably a monohydric alcohol having 15 or less carbon atoms, or a dihydric alcohol having 500 or less molecular weight, and most preferably a dihydric alcohol having 500 or less molecular weight. Examples of the dihydric alcohol having a molecular weight of 500 or less include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and the like. Consider that: the ester or phosphate ester formed from the compound B as described above is less likely to bleed out from the elastic fiber and is likely to be localized on the surface of the monofilament.

In the present embodiment, from the viewpoint of more effectively suppressing the tension fluctuation during traveling, compound a is preferably any of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, and a tricarboxylic acid having 4 or more and 30 or less carbon atoms. The reason why the tension fluctuation during traveling can be more effectively suppressed by using compound a as any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, and a tricarboxylic acid having 4 or more and 30 or less carbon atoms is not clear, but the inventors presume as follows. Consider that: as described above, when the compound a is any one of a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, and a tricarboxylic acid having 4 or more and 30 or less carbon atoms, the viscosity of the yarn surface is reduced, and the magnitude and/or variation of the frictional resistance between the guide and/or the roller positioned in the traveling path of the yarn and the yarn can be reduced, so that the variation in the tension of the yarn during traveling can be reduced.

In the present embodiment, from the viewpoint of more effectively suppressing fuzzing of monofilaments, it is preferable that the compound a is any of a dicarboxylic acid having 4 or more and 30 or less carbon atoms and a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or the compound B is any of a diol having a molecular weight of 3000 or less and a triol having a molecular weight of 3000 or less. The reason why the monofilament is more effectively prevented from unraveling is not clear when compound a is any of a dicarboxylic acid having 4 or more and 30 or less carbon atoms, a tricarboxylic acid having 4 or more and 30 or less carbon atoms, or compound B is any of a diol having a molecular weight of 3000 or less, or a triol having a molecular weight of 3000 or less, that is, when the ester is a polyvalent ester, but the inventors presume as follows. As described above, when the compound a is any one of a dicarboxylic acid having 4 to 30 carbon atoms or less and a tricarboxylic acid having 4 to 30 carbon atoms or the compound B is any one of a diol having 3000 or less molecular weight or a triol having 3000 or less molecular weight, a condensed compound of the compound a and the compound B is likely to bleed out from the elastic fiber and is likely to be localized on the surface of the monofilament, so that the mutual attractive force between the monofilaments is stronger and the monofilaments are less likely to be fluffed.

In the present embodiment, from the viewpoint of more effectively suppressing fuzz of monofilaments, the compound a preferably contains a monocarboxylic acid having 4 or more and 30 or less carbon atoms, a dicarboxylic acid having 4 or more and 30 or less carbon atoms, and a tricarboxylic acid having 4 or more and 30 or less carbon atoms in the aromatic ring, and most preferably contains a monocarboxylic acid having 4 or more and 15 or less carbon atoms, a dicarboxylic acid having 4 or more and 15 or less carbon atoms, and a tricarboxylic acid having 4 or more and 15 or less carbon atoms in the aromatic ring, and specific examples thereof include benzoic acid, phthalic acid, terephthalic acid, and trimellitic acid. The reason why the monofilament is more effectively made less likely to be fluffed by the compound a having an aromatic ring is not clear, but the inventors presume as follows. Consider that: since the compound a has an aromatic ring as described above, an intermolecular force between the aromatic rings also acts, and therefore, the attractive force between the monofilaments becomes stronger, and the monofilaments are less likely to be fluffed.

In the present embodiment, the content of the ester or phosphate ester may be 50ppm or more and 5% or less, more preferably 50ppm or more and 2% or less, still more preferably 100ppm or more and 1.5% or less, and most preferably 100ppm or more and 1% or less, based on the weight of the polyurethane elastic fiber. The content in the present embodiment means a weight% based on the total weight of the polyurethane elastic fiber. When the ester or the phosphate ester is contained in the polyurethane polymer, or is contained in a treating agent such as an oil agent in various ways, the content ratio means the total value of the above. In addition, a plurality of the aforementioned esters or phosphoric acid esters may be contained in the polyurethane elastic fiber at the same time. By setting the content of the ester or the phosphate to 5% or less, the effect of plasticizing the polymer of the ester or the phosphate can be suppressed, and the tension fluctuation during traveling can be reduced. The effect of suppressing the tension fluctuation is more effective by setting the content to 2% or less, more effective by setting the content to 1.5% or less, and most effective by setting the content to 1% or less. Further, the content of the ester or the phosphate ester is 50ppm or more, whereby the effect of suppressing fuzzing of the monofilament can be obtained. This effect is more effective by setting the content to 100ppm or more.

In the present embodiment, the melting point of the ester or phosphate ester contained in the polyurethane elastic fiber is preferably 60 ℃ or lower. Consider that: the melting point is 60 ℃ or lower, whereby the fuzzing of the monofilament can be more effectively suppressed. When the melting point of the ester or phosphate ester is 60 ℃ or lower, the ester or phosphate ester is likely to bleed out from the elastic fiber and is likely to locally exist on the surface of the monofilament.

In the present embodiment, the gas pressure of the ester or phosphate ester contained in the polyurethane elastic fiber is 1.013 × 10⁵The boiling point at Pa is preferably 100 ℃ or higher, and the pressure of the ester or phosphate is set to 1.013 × 10⁵The boiling point at Pa is 100 ℃ or higher, so that the ester or phosphate is less likely to volatilize and is likely to remain in the polyurethane elastic fiber, and therefore, the fuzzing of the monofilament can be more effectively suppressed.

In the present embodiment, the molecular weight of the ester or phosphate ester contained in the polyurethane elastic fiber is preferably 5000 or less, more preferably 2000 or less, and still more preferably 1000 or less, from the viewpoint of effectively suppressing fuzzing of the monofilament. By reducing the molecular weight of the ester or phosphate, the fluidity of the ester or phosphate is improved, and the ester or phosphate is likely to bleed out from the monofilament.

In the present embodiment, the ester or phosphate ester contained in the polyurethane elastic fiber preferably has an oxygen atom other than an ester group. By having an oxygen atom other than an ester group, fuzzing of the monofilament can be more effectively suppressed. When the ester or the phosphate ester has an oxygen atom other than an ester group, intermolecular force between the oxygen atoms other than the ester group in the ester or the phosphate ester acts, the mutual attraction between the monofilaments becomes stronger, and the monofilaments are less likely to be fluffed.

In the present embodiment, the ester or phosphate ester may be a condensate of the compound a and the compound B, and preferably has an aromatic ring from the viewpoint of more effectively suppressing fuzzing of monofilaments. Examples of the ester or phosphate having no aromatic ring include: bis (2-cyclohexyl) adipate, trimethyl citrate, bis (2-ethylhexyl) adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, etc. Examples of the ester or phosphate having an aromatic ring include: benzoic acid esters such as methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, hexyl benzoate, 2-ethylhexyl benzoate, phenyl benzoate, benzyl benzoate, ethylene glycol benzoate, propylene glycol benzoate, diethylene glycol benzoate, dipropylene glycol benzoate, ethylene glycol dibenzoate, propylene glycol dibenzoate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, 1, 4-cyclohexanedimethanol dibenzoate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, bis (2-ethylhexyl) phthalate, diisononyl phthalate, dibenzyl phthalate, dicyclohexyl phthalate, dibutylbenzyl phthalate, etc., phthalic acid esters such as benzyl benzoate, propyl benzoate, butyl benzoate, hexyl benzoate, 2-ethylhexyl benzoate, benzyl phthalate, etc, Terephthalic acid esters such as dimethyl terephthalate, diethyl terephthalate, dibutyl terephthalate, diisobutyl terephthalate, dihexyl terephthalate, bis (2-ethylhexyl) terephthalate, diisononyl terephthalate, dibenzyl terephthalate, dicyclohexyl terephthalate, and butylbenzyl terephthalate, trimellitic acid esters such as trimethyl trimellitate, trioctyl trimellitate, and tri (2-ethylhexyl) trimellitate, and aromatic phosphate esters such as triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, and diphenyl (2-ethylhexyl) phosphate. From the viewpoint of more effectively suppressing fuzzing of monofilaments, the ester or phosphate ester is more preferably a benzoate ester such as methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, hexyl benzoate, 2-ethylhexyl benzoate, phenyl benzoate, benzyl benzoate, ethylene glycol benzoate, propylene glycol benzoate, diethylene glycol benzoate, dipropylene glycol benzoate, ethylene glycol dibenzoate, propylene glycol dibenzoate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, 1, 4-cyclohexanedimethanol dibenzoate, or the like. From the viewpoint of most effectively suppressing fuzz of monofilaments, the ester or phosphate is preferably a benzoate having a plurality of aromatic rings, and specifically, ethylene glycol dibenzoate, propylene glycol dibenzoate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, and 1, 4-cyclohexanedimethanol dibenzoate are most preferable.

In the present embodiment, the fineness of the polyurethane elastic fiber is preferably 100dtex or more. By setting the fineness to 100dtex or more, the thermal breakage can be more effectively suppressed.

In the present embodiment, the number of filaments of the polyurethane elastic fiber that is a multifilament yarn is preferably 20 or more. By setting the number of filaments to 20 or more, a polyurethane elastic fiber having high stretchability can be easily obtained.

In the present embodiment, the filament fineness of the polyurethane elastic fiber is preferably 30dtex or less. When the fiber size of the yarn is 30dtex or less, the solvent can be efficiently evaporated in the case of production by the dry spinning method.

In the present embodiment, it is preferable that the ester or phosphate is contained in an amount of 50ppm to 5% by weight based on the weight of the polyurethane elastic fiber, and the ratio of the maximum value to the minimum value of the diameters of the monofilaments constituting the multifilament is 1.1 to 2.0, since the effect of the monofilament unraveling is further increased. The ratio of the maximum value to the minimum value of the monofilament diameter is more preferably 1.2 or more and 2.0 or less, and still more preferably 1.2 or more and 1.9 or less. By setting the ratio of the maximum value to the minimum value of the filament diameter to 2.0 or less, the deviation of the tension of each filament is reduced, and the tension fluctuation during traveling can be suppressed, so that the breakage can be reduced. This effect is more effective by setting the ratio of the maximum value to the minimum value of the monofilament diameter to 1.9 or less. Further, the ratio of the maximum value to the minimum value of the filament diameter is 1.1 or more, whereby the filaments are less likely to be fluffed, and this effect is more effective by setting the ratio of the maximum value to the minimum value of the filament diameter to 1.2 or more. The reason why the filaments are less likely to be fluffed by setting the ratio of the filament diameters to 1.1 or more in this way is not always the case, but the inventors presume as follows. In the elastic fiber of the multifilament, monofilaments are twisted in a false twisting step and a winding step in production, and many monofilaments are entangled with each other in a complicated manner. Consider that: when the ratio of the maximum value to the minimum value of the filament diameter is 1.1 or more, the filaments are more complicated to wind each other, and therefore, the effect of the ester or the phosphate ester is further increased, and the filaments are less likely to be fluffed. The method for controlling the ratio of the maximum value to the minimum value of the monofilament diameter is not particularly limited, and the following method can be suitably used: the filaments discharged from 2 spinnerets having different numbers of holes were combined to produce polyurethane elastic fibers. Specifically, the following methods are used: the polyurethane dope was extruded from 2 spinnerets having different numbers of holes so as to have the same weight, and the solvent was evaporated to form 2 filaments having the same fineness and different numbers of filaments, which were then combined in a false twisting step to produce 1 polyurethane elastic fiber. More specifically, for example, when the polyurethane dope is extruded from the spinnerets having the hole numbers of 48 and 24 to form 2 filaments by the weight of the filament of 310dtex, respectively, and the filaments are combined in the false twisting step, the polyurethane elastic fiber as a whole becomes 620dtex, the filament number becomes 72, and the filament diameter of the monofilament from the spinneret having the hole number of 24 is about 1.5 times as large as that of the monofilament from the hole number of 48, so that the ratio of the maximum value to the minimum value of the filament diameter can be made about 1.5. As another method for controlling the ratio of the maximum value to the minimum value of the monofilament diameter, it is also possible to suitably use: a method of adjusting the temperature in the spinning tube during spinning to make the filaments properly shake; and a method of controlling the tension of the elastic fiber in the spinning tube by adjusting the speed of the godet roller during winding.

In the present embodiment, the flow-out starting temperature of the polyurethane elastic fiber measured by a flow tester is preferably 200 ℃ or higher. By setting the flow-out initiation temperature to 200 ℃ or higher, sufficient heat resistance can be obtained without causing breakage due to heat even if a step of applying high-temperature heat to the polyurethane elastic fiber is present during processing. The method for producing the polyurethane elastic fiber having the flow-out initiation temperature of 200 ℃ or higher is not particularly limited, and examples thereof include the following methods: a method of making the number average molecular weight of the polyurethane polymer to be a predetermined value or more; a method for increasing the content of a hard segment in a polymer; a method of adding a known heat resistance improver, and the like. Further, the chain extender constituting the polyurethane elastic fiber may be selected from the group consisting of a low molecular weight diamine and a low molecular weight diol, and if the low molecular weight diamine is used, the hard segment containing urea groups can be constituted, and a stronger hydrogen bonding force acts than the hard segment containing urethane groups in the case of using the low molecular weight diol, so that the flow initiation temperature becomes high, and the flow initiation temperature becomes easy to be 200 ℃ or higher.

In the present embodiment, from the viewpoint of more effectively suppressing fuzz of the monofilament and more effectively improving the antistatic property (i.e., the difficulty of occurrence of static electricity) during running, the urethane containing a tertiary amine or the urea compound containing a tertiary amine is preferably contained in an amount of 0.01% to 5% by weight, more preferably 0.01% to 3% by weight, and further preferably 0.03% to 3% by weight, based on the weight of the polyurethane elastic fiber. The urethane containing tertiary amine or urea compound containing tertiary amine may contain a tertiary amine group and a urethane or urea group in a molecule, and the position of the tertiary amine group and the urethane or urea group in the molecule is not limited and may be located at a terminal or may be located in the molecule instead of at a terminal. The number of tertiary amine groups and urethane or urea groups contained in the molecule is not particularly limited, and the presence or absence of substituents in the molecule and the molecular weight are not particularly limited. The reason why monofilaments are more effectively made less likely to shed hairs by containing 0.01% to 5% of a urethane containing a tertiary amine or a urea compound containing a tertiary amine is not clear, but the inventors presume as follows. Consider that: by incorporating a urethane containing a tertiary amine or a urea compound containing a tertiary amine into the polyurethane elastic fiber, the ester or phosphate is likely to be locally present on the surface of the monofilament due to the effect of promoting the bleeding of the ester or phosphate from the elastic fiber, so that the mutual attraction between the monofilaments becomes stronger and the monofilaments are less likely to be fluffed. This effect becomes more effective if 0.03% or more of a urethane containing a tertiary amine or a urea compound containing a tertiary amine is contained. From the economical viewpoint, the content of the urethane containing tertiary amine or the urea compound containing tertiary amine is preferably 5% or less. The reason why the urethane containing a tertiary amine or the urea compound containing a tertiary amine is contained in an amount of 0.01% to 5% to more effectively exhibit the antistatic property during traveling is not clear, but the inventors presume as follows. This is considered to be because the urethane elastic fiber contains a urethane containing a tertiary amine or a urea compound containing a tertiary amine, and the urethane or urea compound interacts with the polar portion of the ester group of the ester compound, that is, the oxygen atom and the nitrogen atom, to form a channel for electrons, so that the urethane becomes less likely to be charged. This effect becomes more effective if 0.03% or more of a urethane containing a tertiary amine or a urea compound containing a tertiary amine is contained.

In the present embodiment, from the viewpoint of more effectively suppressing fuzz of the monofilament and more effectively improving the antistatic property during running, the urethane compound containing a tertiary amine is preferably a urethane compound having a repeating unit represented by the following formula (1):

{ formula (II) wherein R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-10 hydrocarbon group. Or a urethane compound having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):

{ formula (II) wherein R₁Is a C5-30 2-valent hydrocarbon group, R₂And R₃Independently of each other, a C1-10 2-valent hydrocarbon group, and R₄Is a C1-10 hydrocarbon group. }

{ formula (II) wherein R₅Is a C5-30 2-valent hydrocarbon group, and R₆Is a C1-10 2-valent hydrocarbon group or polyoxyalkylene group. }. In addition, the urea compound containing a tertiary amine is preferably a urea compound represented by the following formula (3):

{ formula (II) wherein R₇And R₈Independently of each other, is a C1-10 hydrocarbon group having a valence of 1 to 10, and R₉Is a C5-30 2-valent hydrocarbon group. }.

R₁And R₅More preferably, the aliphatic hydrocarbon groups are independently a 2-valent hydrocarbon group having 5 to 15 carbon atoms, and further preferably have an alicyclic hydrocarbon structure, and most preferably have an alicyclic hydrocarbon structure belonging to a six-membered ring.

R₂、R₃More preferably a C1-5 hydrocarbon group. The hydrocarbon group having 1 to 5 carbon atoms is not limited to the following, and examples thereof include: methylene, ethylene, propylene, trimethylene, butylene, 2-methylpropylene, pentylene, and the like.

R₄More preferably a C1-5 hydrocarbon group. The hydrocarbon group having 1 to 5 carbon atoms is not limited to the following, and examples thereof include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, tert-pentyl, and the like.

R₆More preferably a C2-4 hydrocarbon group having 2 valence, oxyethylene group, oxypropylene group, oxytetramethylene group, polyoxyethylene group, polyoxypropylene group, polyoxytetramethylene group. The molecular weight of oxytetramethylene, polyoxyethylene, polyoxypropylene, and polyoxytetramethylene is not particularly limited.

The number of repeating units represented by formula (1) and the number of repeating units represented by formula (2) contained in the tertiary amine-containing urethane compound are not particularly limited, and the tertiary amine-containing urethane compound may have a repeating unit represented by formula (1) and a repeating unit represented by formula (2) at arbitrary positions in the molecule.

R₇、R₈More preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 5 carbon atoms is not limited to the following, and examples thereof include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, tert-pentyl, and the like.

R₉More preferably a hydrocarbon group having 5 to 15 carbon atoms, and still more preferably having an aromatic ring structure. The structure having an aromatic ring structure is not limited to the following, and examples thereof include: benzene structure, diphenylmethane structure, and the like.

Specific examples of the urethane compound having a repeating unit represented by formula (1) are not particularly limited, and include: a compound 4 obtained by copolymerizing isophorone diisocyanate and N-butyldiethanolamine, which has a repeating unit represented by the following formula (4):

a compound 5 obtained by copolymerizing dicyclohexylmethane 4,4 '-diisocyanate and 1, 1' - (N-methylimino) di-2-propanol, said compound having a repeating unit represented by the following formula (5):

or a compound 6 obtained by copolymerizing isophorone diisocyanate with 1, 1' - { N- (tert-butyl) imino } di-2-propanol, which has a repeating unit represented by the following formula (6):

specific examples of the urethane compound having the repeating unit represented by formula (1) and the repeating unit represented by formula (2) are not particularly limited, and include: a compound 7 having a repeating unit represented by the following formula (7) and a repeating unit represented by the following formula (8), which is obtained by copolymerizing dicyclohexylmethane 4, 4' -diisocyanate, N- (tert-butyl) diethanolamine, and 1, 4-butanediol:

specific examples of the compound represented by formula (3) are not particularly limited, and examples thereof include a compound 8 represented by formula (9) below, and a compound 9 represented by formula (10) below:

in the present embodiment, from the viewpoint of more effectively suppressing fuzz of monofilaments and more effectively improving antistatic properties during running, the content of the tertiary amine-containing urethane or the tertiary amine-containing urea compound is preferably larger than the content of the ester or the phosphate, and the content of the tertiary amine-containing urethane or the tertiary amine-containing urea compound is more preferably 5 times or more and 200 times or less, further preferably 10 times or more and 150 times or less, further preferably 20 times or more and 150 times or less, and most preferably 30 times or more and 150 times or less of the ester or the phosphate.

In the present embodiment, the elongation of the polyurethane elastic fiber on the wound yarn body is preferably 5% or less. In general, polyurethane elastic fibers are wound around a paper tube in a state of being stretched more than a relaxed state to form a wound body. In the state of the wound yarn body, the ratio of the elongation of the polyurethane elastic fiber with respect to the relaxed state is referred to as the elongation on the wound yarn body. By setting the elongation to 5% or less, the stress fluctuation required when unwinding the elastic fiber from the wound yarn body is reduced, and therefore, the tension fluctuation during running can be more effectively suppressed. The method for adjusting the elongation to 5% or less is not particularly limited, and examples thereof include: and a method for adjusting the speed ratio between the godet roller and the winding bobbin when the polyurethane elastic fiber is wound.

Since the elastic polyurethane fiber of the present embodiment is less likely to fluff a monofilament, has a small tension fluctuation during running, and is excellent in antistatic property during running, it is less likely to break when blended with natural fibers such as cotton, silk, and wool, polyamide fibers such as nylon 6 and nylon 66, polyester fibers such as polyethylene terephthalate, 1, 3-propanediol terephthalate, and 1, 4-butanediol terephthalate, cationic dyeable polyester fibers, cuprammonium regenerated rayon, viscose rayon, and acetate rayon, or processed yarns formed by covering, cross-winding, and cabling these fibers are used to form a processed yarn, and then blended to obtain a fabric, and high productivity can be obtained.

The fabric using the polyurethane elastic fiber of the present embodiment can be suitably used for various stretch bases (stretch foundation) such as swimwear, a waistband, a brassiere, a private product, and underwear, tights, stockings, a waistband, jumpsuits, foot protectors, stretch sportswear, stretch outerwear, medical clothing, and stretch linings. Even if the fabric using the polyurethane elastic fiber of the present embodiment is subjected to a heat treatment process such as pre-setting, dyeing, and final setting, monofilaments of the polyurethane elastic fiber in the fabric are less likely to be cut under heat conditions, and the occurrence of defective products can be suppressed, so that high productivity can be obtained.

The monofilament of the polyurethane elastic fiber of the present embodiment is less likely to loose wool, has a small tension variation during running, has excellent antistatic properties during running, and is less likely to be cut even under hot conditions, and therefore, breakage can be sufficiently suppressed, and therefore, sanitary materials such as sanitary products and disposable diapers can be manufactured with high productivity, and further, breakage and needle-off in members are less likely to occur, and the occurrence of defective products of these products can be suppressed.