JP2002363822A - Hygroscopic polyurethane elastic fiber and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a product having excellent wearing and taking off properties, fittedness, appearance quality, a feeling of wearing, moisture absorbing and releasing properties, antistatic properties, etc. SOLUTION: This polyurethane elastic fiber is characterized in that a polyurethane comprises a polyol containing a block copolymer of tetrahydrofuran and ethylene oxide, a diisocyanate and a diol as main constituent components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-absorbing polyurethane elastic fiber having excellent desorption properties, fit properties, appearance quality, feeling of wearing, moisture absorption / release properties, antistatic properties and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Polyurethane elastic fibers are widely used in legwear such as stockings, innerwear, and sportswear because of their excellent elasticity. In order to further improve the elasticity function of the wear, the content of the polyurethane elastic fiber in the fabric is further increased.

[0003] By using a stocking or innerwear having a high mixing ratio of polyurethane elastic fiber, its elasticity, wearing feeling, and the like can be made better than conventional ones.

[0004] The same applies to other uses other than stockings and innerwear. However, when the mixing ratio of polyurethane elastic fibers is increased, these polyurethane elastic fibers have extremely low moisture absorption / release properties compared to mixed hard yarns, for example, polyamide fibers and natural fibers. When used in a field where the skin is directly touched or worn close to the skin, sweating from the skin tends to cause stuffiness, stickiness, etc., and the comfort tends to be reduced.

[0005] To solve this problem, several means have been tried, from raw yarn to high-order processing. As a solution, there is a method in which a magnesium salt is compounded into polyurethane as a compound for enhancing moisture absorption / desorption as a means from the yarn side.
No. 2,714,432.

Further, a method of blending a polyurethane using polyethylene glycol as a raw material is disclosed in JP-A-2000-144.
No. 532. Japanese Patent Application Laid-Open No. 9-41204 discloses a method using a specific polyamide fiber having a high moisture absorption / release property as a hard yarn mixed with a polyurethane elastic fiber as a means from a higher processing surface.

However, these methods have insufficient effects to solve the above-mentioned objects, and in particular, have failed to impart sufficient moisture absorption / release properties to polyurethane elastic fibers.

[0008] Also, when a hard yarn having a high moisture absorption / release property is used in the high-order processing stage, there are problems such as an increase in cost and difficulty in coping with all uses.

[0009]

When the moisture-absorbing polyurethane elastic fiber of the present invention is used for clothes, the feeling of wearing, desorption, fitting, moisture absorption / desorption, appearance quality, antistatic property of the obtained clothes and the like are obtained. Etc. can be made excellent.

An object of the present invention is to provide a moisture-absorbing polyurethane elastic fiber capable of imparting a feeling of wearing, a desorption property, a fitting property, a moisture absorbing / releasing property, an appearance quality, an antistatic property and the like to a product, and a method for producing the same. It is in.

[0011]

Means for Solving the Problems The moisture absorbing polyurethane elastic fiber of the present invention employs the following means to solve the above-mentioned problems.

That is, the polyurethane elastic fiber is a polyurethane whose main component is a polyol, a diisocyanate and a diol, wherein the polyol contains a block copolymer of tetrahydrofuran and ethylene oxide.

Further, the method for producing a moisture-absorbing polyurethane elastic fiber of the present invention employs the following means in order to solve the above-mentioned problems.

That is, a method for producing a polyurethane elastic fiber, comprising spinning a polyurethane solution containing a polyurethane containing a block copolymer of tetrahydrofuran and ethylene oxide, a diisocyanate and a diol as main components as a solute. It is.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the moisture-absorbing polyurethane elastic fiber of the present invention will be described in more detail.

The moisture-absorbing polyurethane elastic fiber of the present invention comprises:
It is a polyurethane whose main constituents are polyols, diisocyanates and diols.

The method for synthesizing the polyurethane is not particularly limited. In particular, polymerization is preferably performed in a solution from the viewpoint of efficiently performing the reaction. Note that trifunctional or higher polyfunctional glycols and isocyanates may be used as long as the effects of the present invention are not impaired.

Here, typical structural units constituting the polyurethane of the present invention will be described.

The polyol used in the present invention is a so-called block copolymer in which tetrahydrofuran (hereinafter abbreviated as THF) and ethylene oxide are regularly arranged.

In the present invention, if no block copolymer is used, there is a problem that the obtained polyurethane elastic fibers have poor water absorption.

That is, the polyol used in the present invention is:
It can also be described as poly (tetramethylene-co-ethylene ether) glycol.

In the poly (tetramethylene-co-ethylene ether) glycol, the ethylene ether accounts for 15 to 37 mol% based on the total alkylene ether.
It is preferably contained, more preferably 20 to 35 mol%.

Further, the polyol used in the present invention may be composed of only a block copolymer, or may be copolymerized with another polyol, or may be further mixed with another polyol. It may be.

As other polyols, excellent cold resistance,
Poly (1,4-tetramethylene glycol) (hereinafter abbreviated as PTMG), Patent No. 261513, from the viewpoint of obtaining a material having high extensibility and high recoverability.
No. 1, diol containing a neopentyl group in the main chain, polycarbonate diol disclosed in JP-A-2-289616, etc., JP-A-5-9851
No. 1, the ester-based diols disclosed in
It is preferable to use 4-butanediol, 1,6-hexanediol, polycaprolactonediol, polyethylene ether glycol, polypropylene ether glycol, a copolymerized polyol of neopentylene oxide and tetrahydrofuran, or the like. And such another polyol may be one kind, or may be two or more kinds.

In the present invention, the molar fraction of ethylene oxide units is preferably in the range of 5 to 90%.

The weight average molecular weight of the polyol used in the present invention is preferably in the range of 1,000 or more and 6000 or less from the viewpoints of elongation, strength, heat resistance and the like when formed into yarn.

More preferably, it is in the range of 1300 or more and 4500 or less. By using a polyol having a molecular weight in this range, an elastic yarn having well-balanced mechanical properties can be obtained.

Next, the diisocyanate used in the present invention is
For example, 5-isocyanate-1- (isocyanatomethyl) -1,3,3-trimethylcyclohexane, 1-
Isocyanate-4-[(4-isocyanatophenyl) methyl] benzene, 1-isocyanate-2-
[(4-Isocyanate-phenyl) methyl] benzene, 1,1′-methylenebis (4-isocyanatocyclohexane), 4-methyl-1,3-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI) ), 2,4-tolylene diisocyanate (hereinafter abbreviated as TDI), 1,4-
Aromatic diisocyanates such as diisocyanate benzene, xylylene diisocyanate, and 2,6-naphthalenedi isocyanate are particularly preferable for synthesizing polyurethane having high heat resistance and strength.

Further, as the alicyclic diisocyanate, for example, methylene bis (cyclohexyl isocyanate)
(Hereinafter abbreviated as H ₁₂ MDI), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate,
Preferred are cyclohexane 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, octahydro 1,5-naphthalenediisocyanate, and the like. Aliphatic diisocyanates are preferably used particularly for suppressing yellowing of polyurethane yarns.

These diisocyanates may be used alone or in combination of two or more.

The ratio of the molar amounts of such diisocyanates is:
From the viewpoint of the strength characteristics of the obtained polyurethane elastic fiber,
It is preferable that the diisocyanate is in the range of 1.2 or more and 2.3 or less with respect to the polyol 1.

Next, a low molecular weight diol is used as the chain extender used in the present invention.

As the low molecular weight diol, ethylene glycol, 1,3 propanediol, 1,4 butanediol, 1,2-propylene glycol, 3-methyl-1,
5-pentanediol, 2,2-dimethyl-1,3-trimethylenediol, 2,2,4-trimethyl-1,5
-Pentanediol, 2-methyl-2-ethyl-1,3
-It is preferable to use propanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate and the like.

It is also preferable to use one or more of these materials. In particular, from the viewpoint of obtaining a polyurethane elastic fiber having high heat resistance and high strength as a diol-extended polyurethane, ethylene glycol,
It is preferable to use 1,3 propanediol and 1,4 butanediol.

The moisture-absorbing polyurethane elastic fiber of the present invention includes so-called BHT and "SUMILIZER" GA-80 manufactured by Sumitomo Chemical Co., Ltd. as ultraviolet absorbers, antioxidants and gas-resistant stabilizers. Hindered phenolic drugs, various "tinuvins" and other benzotriazole drugs, Sumitomo Chemical Co., Ltd. "Sumilyzer" P-16 and other phosphorus drugs, various "tinuvins" Hindered amine-based agents, inorganic pigments such as titanium oxide, zinc oxide, and carbon black; metal soaps such as magnesium stearate; and disinfectants and deodorants containing silver, zinc, and these compounds. And lubricants such as silicone and mineral oil, barium sulfate, cerium oxide, betaine and phosphoric acid. It is also preferred that the reacted or contain various antistatic agents, also a polymer.

In order to further increase the durability especially against light and various types of nitric oxide, a nitric oxide supplement such as HN-150 manufactured by Nippon Hydrazine Co., Ltd.
For example, "Sumilyzer" GA- manufactured by Sumitomo Chemical Co., Ltd.
80, it is preferable to use a light stabilizer such as "Sumisorb" 300 # 622 manufactured by Sumitomo Chemical Co., Ltd.

The fineness, cross-sectional shape and the like of the moisture-absorbing polyurethane elastic fiber of the present invention are not particularly limited. For example, the cross section may be circular or flat.

Further, in the moisture-absorbing polyurethane elastic fiber of the present invention, the residual strain at -5 ° C. is preferably 90% or less, more preferably 50% or less, and further preferably 26% or less.

Next, the method for producing the hygroscopic polyurethane elastic fiber of the present invention will be described in detail.

In the present invention, it is preferable to prepare a polyurethane solution first.

In the present invention, any method may be used for producing the polyurethane, which is a solute of the polyurethane solution, and for producing the polyurethane solution.

That is, either the melt polymerization method or the solution polymerization method may be used. However, more preferred is the solution polymerization method. In the case of the solution polymerization method, the generation of foreign substances such as gel in the polyurethane is small. Also, needless to say, solution polymerization is preferable from the viewpoint of production efficiency because labor for preparing a solution is omitted.

In the present invention, a polyurethane containing a block copolymer of tetrahydrofuran and ethylene oxide, a diisocyanate and a diol as main components is used.

Of these, the polyol has a weight average molecular weight in the range of 1,000 to 6,000, and the diol as a chain extender is at least one selected from the group consisting of ethylene glycol, 1,3 propanediol and 1,4 butanediol. The diisocyanate is preferably a polyurethane synthesized in a solution using MDI as a main raw material.

Such polyurethane is, for example, DMA
C, DMF, DMSO, NMP, or the like, or a solvent containing these as a main component, can be obtained by synthesizing the above-mentioned raw materials.

For example, the so-called one-shot method, in which each raw material is charged and dissolved in such a solvent and heated to an appropriate temperature to cause a polyurethane to react, or a polyol and MDI are first melt-reacted, and then the polyurethane is melted. A method in which the reactant is dissolved in a solvent and reacted with the above-mentioned diol to form a polyurethane can be employed as a particularly suitable method.

When synthesizing such a polyurethane,
An amine catalyst or an organometallic catalyst may be used alone or in combination of two or more. Typical examples thereof include amine catalysts such as N, N-dimethylcyclohexylamine, N, N-dimethylbenzylamine, triethylamine, N-methylmorpholine,
Ethylmorpholine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethyl-1,3-propanediamine, N, N, N ', N'-tetramethylhexane Diamine, bis-2-dimethylaminoethyl ether, N, N, N ', N', N'-pentamethyldiethylenetriamine, tetramethylguanidine, triethylenediamine, N, N'-dimethylpiperazine, N-methyl-N'- Dimethylaminoethyl-piperazine, N- (2-dimethylaminoethyl) morpholine, 1-methylimidazole, 1,2-dimethylimidazole, N, N-dimethylaminoethanol, N, N,
N'-trimethylaminoethylethanolamine, N-
Methyl-N ′-(2-hydroxyethyl) piperazine,
2,4,6-tris (dimethylaminomethyl) phenol, N, N-dimethylaminohexanol, triethanolamine and the like can be preferably used. As the organometallic catalyst, tin octoate, dibutyl tin dilaurate, lead dibutyl octoate and the like can be preferably used.

Further, in the present invention, it is preferable to use a chain terminator in order to control the molecular weight of the polyurethane and the viscosity of the polyurethane spinning solution.

As such a chain terminator, n-butanol,
Diethylamine, cyclohexylamine, n-hexylamine and the like are preferred.

It is preferable that the chain terminating agent is usually used as a mixture with a chain extender.

Also, small amounts of trifunctional substances such as diethylenetriamine and glycerol can be used to control polymer viscosity.

The concentration of the polyurethane solution thus obtained is not particularly limited, but is usually preferably in the range of 30% by weight to 80% by weight.

In the present invention, it is preferable to add the various additives described above to such a polyurethane solution. As a method of adding the additive to the polyurethane solution, any method can be adopted. Typical examples thereof include a method using a static mixer and a method using stirring.

Here, the additives are preferably added in the form of a solution. If it is a solution, it can be uniformly added to the polyurethane solution.

In the present invention, a polyurethane solution is spun to obtain a polyurethane elastic fiber. The spinning method may be any of a wet method, a dry method, and a melting method.

From the viewpoint of increasing the spinning speed, spinning is preferably performed by a dry method. In dry spinning, at least two gas supply units are provided, and when a gas suction unit is used to form a fiber by discharging a polyurethane solution from a spinneret to a spinning cylinder provided between the gas supply units, The temperature of the gas supplied from the gas supply unit provided at the lower part of the spinning cylinder is set to 6
The temperature is preferably set to 0 ° C. or lower from the viewpoint of eliminating yarn unevenness.

In spinning, the speed ratio between the godet roller and the winder is preferably determined according to the purpose of use of the yarn.

In the present invention, it is preferred that the speed ratio between the godet roller and the winder is 1.1 or more and 1.8 or less for winding.

The spinning speed is 300 m / min or more and 800
It is preferably at most m / min.

[0060]

The present invention will be described in more detail by way of examples. However, the present invention is not limited by these examples.

The method of quantifying stress relaxation, strength, elongation, residual strain, and moisture absorption / desorption in the present invention will be described. [Stress relaxation, strength, elongation, residual strain] Stress relaxation, strength,
For elongation and residual strain, use polyurethane yarn with Instron 45.
It was obtained by performing a tensile test using a 02 type tensile tester.

The stress relaxation, strength and elongation were measured at 22 ° C., and the residual strain was measured at −5 ° C.

These are defined below.

A 5 cm (L1) sample was subjected to 300% elongation five times at a pulling speed of 50 cm / min. The stress at this time was defined as (G1).

Next, the length was held for 30 seconds. The stress after holding for 30 seconds was defined as (G2).

The sample length when the stress is set to 0 is (L
2).

Further, the polyurethane yarn was stretched until the polyurethane yarn was cut.

The stress at break was (G3), and the sample length at break was (L3).

Hereinafter, the above characteristics were obtained by the following equation.

Strength = (G3) Stress relaxation (%) = 100 × ((G1) − (G2)) /
(G1) Residual strain (%) = 100 × ((L2) − (L1)) /
(L1) Elongation (%) = 100 × ((L3) − (L1)) / (L
1) [Hygroscopicity] Moisture absorption / desorption coefficient ΔM as an index indicating hygroscopicity
R was adopted.

The moisture absorption / desorption coefficient ΔMR is as follows: when the sample is a yarn, a knitted fabric of about 1 g obtained by knitting the yarn is used, and when the sample is an additive of a hygroscopic component, it is 0.125 μm. Approximately 1 g of film cast from a DMAc solution was used. From the weight change between the weight of about 1 g of the sample at the time of absolute drying and the weight after being left in a thermo-hygrostat for 24 hours in an atmosphere of 20 ° C. × 65% RH or 30 ° C. × 90% RH, it was obtained by the following equation. .

Moisture absorption (%) = [(weight after moisture absorption−weight when absolutely dry) / weight when absolutely dry] × 100 20 ° C. × 65% RH and 30 ° C. × 90% measured above.
From the moisture absorption rate under the condition of RH (referred to as MR1 and MR2, respectively), the moisture absorption / desorption coefficient ΔMR (%) = MR2-MR1
Was calculated.

The moisture absorption / desorption coefficient ΔMR when the sample is a yarn is a driving force for obtaining comfort by releasing moisture in the clothes to the outside air when the clothes are worn, and includes light to medium work or light to medium exercise. ℃ 90% RH at the time of performing
Is the difference between the moisture absorption rate between the temperature inside the clothes represented by the formula (1) and the outside temperature and humidity represented by the temperature of 20 ° C. × 65% RH. The larger the ΔMR, the higher the hygroscopicity and the better the comfort when worn.

Example 1 A block copolymer having a ratio of THF to ethylene oxide of 7: 3 and a molecular weight of 2,000 was 2770 g of a polyol, MDI 1065 g, ethylene glycol 176 g and dimethylacetamide 6
017 g was charged into the reactor and stirred at 70 ° C. under a nitrogen stream. When the stirring torque reached a predetermined value, 16 g of n-butanol was added to terminate the reaction, and a 40% by weight polyurethane solution was obtained. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution was dried at an atmosphere temperature of 3.
The mixture was discharged into a nitrogen gas at 80 ° C., and was subjected to dry spinning at a speed of 540 m / min with a speed ratio of a godet roller and a winder of 1.42 to obtain a monofilament yarn of 20 dtex.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at -5 ° C. of this yarn.

Using the obtained yarn, a tubular knitted fabric was knitted. The moisture absorption / desorption coefficient ΔMR of this knitted fabric was 5.1.

[0077]

[Table 1]

[Example 2] A block copolymer having a ratio of THF to ethylene oxide of 7: 3 and a molecular weight of 2,000, 2674 g of polyol, MDI 1130.25
g, 195.36 g of ethylene glycol and 5997.7 g of dimethylacetamide were charged into the reactor, and the mixture was stirred at 70 ° C. under a nitrogen stream. When the stirring torque reached a predetermined value, 16 g of n-butanol was added to terminate the reaction, and a 40% by weight polyurethane solution was obtained. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution was discharged into a nitrogen gas at a drying atmosphere temperature of 380 ° C., and the speed ratio between the godet roller and the winder was 1.42 and 540 m /
By dry spinning at a speed of 20 minutes, a monofilament yarn of 20 dtex was obtained.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at −5 ° C. of the yarn.

Using the obtained yarn, a tubular knitted fabric was knitted. The moisture absorption / desorption coefficient ΔMR of this knitted fabric was 5.3.

Example 3 3556 g of a polyol, a block copolymer having a molecular weight of 3300, a ratio of THF to ethylene oxide of 7: 3 and a molecular weight of 3300, 3556 g of MDI, 142.6 g of ethylene glycol and 6785.4 g of dimethylacetamide were charged into a reactor. And under a nitrogen stream, 70
Stirred at ° C. When the stirring torque reaches a predetermined value, n
The reaction was terminated by adding 18 g of butanol to obtain a 40% by weight polyurethane solution. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution is discharged into a nitrogen gas at a dry atmosphere temperature of 380 ° C., and is subjected to dry spinning at a speed of 540 m / min with a speed ratio of a godet roller and a winder of 1.42, thereby forming a 20 dtex monofilament yarn. Obtained.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at -5 ° C. of this yarn.

Using the obtained yarn, a tubular knitted fabric was knitted. The moisture absorption / desorption coefficient ΔMR of this knitted fabric was 4.5.

Example 4 3556 g of a polyol which is a block copolymer having a ratio of THF to ethylene oxide of 7 to 3 and a molecular weight of 3300, 3875 g of MDI, 155 g of ethylene glycol, 155 g of ethylene glycol and dimethylacetamide 68
79 g was charged into the reactor, and stirred at 70 ° C. under a nitrogen stream. When the stirring torque reached a predetermined value, 18 g of n-butanol was added to terminate the reaction, and a 40% by weight polyurethane solution was obtained. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution is dried at an atmosphere temperature of 380.
The mixture was discharged into a nitrogen gas at a temperature of ° C. and dry-spun at a speed of 540 m / min with a speed ratio of a godet roller and a winder of 1.42 to obtain a monofilament yarn of 20 dtex.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at −5 ° C. of the yarn.

[0086] A tubular knitted fabric was knitted using the obtained yarn. The moisture absorption / desorption coefficient ΔMR of this knitted fabric was 4.8.

Comparative Example 1 A random copolymer having a ratio of THF to ethylene oxide of 7: 3 and a molecular weight of 2,000, 2770 g of a polyol, MDI 1065 g, ethylene glycol 176 g and dimethylacetamide 6
017 g was charged into the reactor and stirred at 70 ° C. under a nitrogen stream. When the stirring torque reached a predetermined value, 16 g of n-butanol was added to terminate the reaction, and a 40% by weight polyurethane solution was obtained. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution was dried at an ambient temperature of 3
The mixture was discharged into a nitrogen gas at 80 ° C., and was subjected to dry spinning at a speed of 540 m / min with a speed ratio of a godet roller and a winder of 1.42 to obtain a monofilament yarn of 20 dtex.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at -5 ° C. of this yarn.

Using the obtained yarn, a tubular knitted fabric was knitted. The moisture absorption / desorption coefficient ΔMR of this tubular knitted fabric was 1.0.

Comparative Example 2 PTMG2 having a molecular weight of 2100
835 g, MDI 1012.5 g, ethylene glycol 167.4 g and dimethylacetamide 6022.4
g was charged into the reactor and stirred at 70 ° C. under a nitrogen stream. When the stirring torque reached a predetermined value, 16 g of n-butanol was added to terminate the reaction, and a 40% by weight polyurethane solution was obtained. A sample solution was prepared by adding an appropriate amount of an antioxidant and a gas-resistant stabilizer to this polyurethane solution. The obtained solution is dried at an atmosphere temperature of 380.
The mixture was discharged into a nitrogen gas at a temperature of ° C. and dry-spun at a speed of 540 m / min with a speed ratio of a godet roller and a winder of 1.42 to obtain a monofilament yarn of 20 dtex.

Table 1 shows the elongation, strength, stress relaxation, and residual strain measured at -5 ° C. of the yarn.

Using the obtained yarn, a tubular knitted fabric was knitted. The moisture absorption / desorption coefficient ΔMR of this tubular knitted fabric was 0.5.

[0093]

The clothes and the like using the present invention have a desorption property,
It is excellent in fit, appearance quality, wearing feeling, moisture absorption / desorption, antistatic properties, and the like. Because of these excellent properties, the moisture-absorbing polyurethane elastic fiber of the present invention is used not only alone, but also in combination with various fibers, for example, foundations such as stockings, girdle, bra, tights, waistband, socks, etc. And intimate goods, swimwear, body suits, spats, ski pants, golf trousers, wet suits, work clothes, smoke suits, clothes and other sportswear, outerwear, circular knitting,
Tightening materials for various fiber products such as tricots, stretch fabrics, linings, bandages, supporters, gloves, socks, etc. It can be used for various applications such as wiping cloths, copy cleaners and gaskets.

Claims (6)

[Claims] 1. A polyurethane elastic fiber comprising a polyurethane whose main constituent is a polyol, a diisocyanate and a diol, wherein the polyol contains a block copolymer of tetrahydrofuran and ethylene oxide. 2. A method according to claim 1, wherein the molar fraction of ethylene oxide units is 5 to 5.
The polyurethane elastic fiber according to claim 1, which is in a range of 90%. 3. The polyol has a molecular weight of 1,000 or more and 60 or more.
The polyurethane elastic fiber according to claim 1 or 2, wherein the polyurethane elastic fiber is in a range of not more than 00. 4. The polyurethane elastic fiber according to claim 1, wherein the residual strain at -5 ° C. is 90% or less. 5. A process for producing a polyurethane elastic fiber, comprising spinning a polyurethane solution containing a polyurethane containing a block copolymer of tetrahydrofuran and ethylene oxide, a diisocyanate and a diol as main components. . 6. The method for producing a polyurethane elastic fiber according to claim 5, wherein the spinning method is dry.