Polyurethane elastic fiber

Abstract

To provide a highly durable polyurethane elastic fiber having high stress during shrinkage, that is, recovery stress, as well as excellent antioxidative properties.SOLUTION: The polyurethane elastic fiber comprises a polyurethane having a polyether structure in its backbone, and a nitrogen-containing aromatic compound. The polyether structure is represented by the general formula (1) in the figure. The content of the nitrogen-containing aromatic compound in the polyurethane elastic fiber is from 0.05 mass% to 2.0 mass% inclusive. (R1 is an alkylene group having 2 to 6 carbon atoms; R2 is an alkyl group having 1 to 2 carbon atoms; and l, m and n satisfy 4≤n / (l+m+n)×100≤50.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyurethane resin composition and a polyurethane elastic fiber, and more particularly to a polyurethane elastic fiber having high durability, high stress during shrinkage, i.e., high recovery stress, and excellent oxidation resistance. [Background technology]

[0002] Due to its excellent elasticity, polyurethane resins are widely used in paints, coatings, sealants, adhesives, pressure sensitive adhesives, textile processing agents, artificial leather, synthetic leather, elastomer raw materials such as rolls, and textile products, etc. In each application, there is a demand to improve the heat resistance of polyurethane resins while maintaining their elasticity (high elastic recovery and high elongation) in order to prevent deterioration due to heat history when producing or processing final products using polyurethane resins as raw materials and to improve the durability of the final products.

[0003] Polyurethane elastic fibers have excellent elastic properties and are widely used in elastic clothing applications such as leg wear, innerwear, and sportswear, as well as in industrial materials.

[0004] Polyurethane elastic fibers are also required to have high elastic recovery, high strength and elongation, high heat resistance, and heat setting properties. In particular, regarding elastic recovery performance, improvements in recovery stress have always been pursued.

[0005] In terms of heat resistance, increasing the melting point improves resistance to heat embrittlement, but the heat setting properties required, particularly when made into fibers, decrease. For this reason, a composition with high oxidizing power has been required for fibers with a large surface area.

[0006] It is known that a polyurethane structure consisting of a copolyether diol of tetrahydrofuran and 3-alkyltetrahydrofuran and a diisocyanate can form a soft segment with a higher stress during shrinkage, i.e., a higher recovery stress, than the former (Patent Documents 1 and 2).

[0007] In addition, examples have been disclosed in which polyurethane elastic fibers exhibit a specific antioxidant effect when they contain an appropriate amount of a nitrogen-containing aromatic compound with respect to heat resistance and heat aging resistance (Patent Documents 3 and 4).

[0008] Furthermore, in recent years, with the growing interest in various environmental issues, efforts toward a sustainable society are being called for for organic materials in general, and polyurethane elastic fibers, which have a relatively low content in elastic materials, are no exception. Because the content in elastic clothing and industrial materials is relatively low, separation and extraction are difficult, making recycling difficult, and thermal recycling may be preferable. For this reason, it has been proposed to use components derived from carbon-neutral biomass resources as raw materials (Patent Documents 5 and 6). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2-19511 [Patent Document 2] Japanese Patent Application Publication No. 9-136937 [Patent Document 3] JP 2008-69506 A [Patent Document 4] WO2009 / 011189 [Patent Document 5] Special Publication No. 2014-522446 [Patent Document 6] JP 2021-152139 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, these conventional techniques have been insufficient in terms of recovery stress or oxidation resistance. Thus, there is a demand for a polyurethane resin composition and polyurethane elastic fiber having high recovery stress and excellent oxidation resistance.

[0011] An object of the present invention is to provide a polyurethane resin composition and polyurethane elastic fiber which have high durability and exhibit high stress during shrinkage, i.e., high recovery stress and excellent oxidation resistance. [Means for solving the problem]

[0012] In response to this problem, the inventors have investigated the case where an alkyl group exists on the carbon atom adjacent to the ether group in tetramethylene ether. That is, the polyurethane structure is composed of a copolyether diol of tetrahydrofuran and 2-alkyltetrahydrofuran, and a diisocyanate. As a result, it has been found that the recovery stress of the polyurethane resin composition and polyurethane elastic fiber is higher in the case of 2-alkyl groups than in the case of 3-alkyl groups. The inventors have also found that the heat resistance behavior is completely different in the case of 2-alkyl groups compared to 3-alkyl groups. That is, it has been found that in the case of 2-alkyl groups, the heat resistance is maximized at a specific addition amount of a nitrogen-containing aromatic compound. These phenomena are thought to be due to the fact that when an alkyl group exists on the carbon atom adjacent to the ether group in tetramethylene ether, the steric hindrance of the alkyl group is more dominant in the case of 2-alkyl groups than in the case of 3-alkyl groups, and from the viewpoint of oxidation resistance, when an alkyl group exists on the carbon atom adjacent to the ether group, the cleavage of the ether oxygen and the adjacent carbon can be suppressed. Therefore, it has been found that it is possible to obtain a polyurethane resin composition and polyurethane elastic fiber that have high recovery stress and excellent oxidation resistance and are highly durable. This allows the material to have both high heat resistance and high durability even when it is made low melting point and highly heat set, making it possible to process it at low temperatures and saving energy to address environmental issues. In addition, it has been proposed to use carbon-neutral components derived from biomass resources that are suitable for thermal recycling as raw materials (Patent Documents 5 and 6). However, it is not rational to use raw materials with new or special chemical structures that have not been widely used until now, and it is important to use non-petrochemical biomass raw materials with known chemical structures, i.e., biomass monomers.

[0013] That is, the present invention has the following configuration. (1) A polyurethane elastic fiber comprising a polyurethane having a polyether structure in the skeleton and a nitrogen-containing aromatic compound, The polyether structure satisfies the following general formula (1): A polyurethane elastic fiber, comprising 0.05% by mass or more and 2.0% by mass or less of a nitrogen-containing aromatic compound.

[0014] [ka]

[0015] (R 1 is an alkylene group having 2 to 6 carbon atoms, R 2 is an alkyl group having 1 to 2 carbon atoms, l, m, n satisfy 4≦n / (l+m+n)×100≦50) (2) The polyurethane elastic fiber according to (1), wherein l, m, and n in the general formula (1) satisfy 6≦n / (l+m+n)×100≦16. (3) A polyurethane elastic fiber according to (1) or (2), in which the polyurethane elastic fiber contains 0.2% by mass or more and 0.8% by mass or less of a nitrogen-containing aromatic compound. (4) In the general formula (1), -(CH2CH2CH2CHR 2 The polyurethane elastic fiber according to any one of (1) to (3), wherein n' is the number of terminals among -O)n-, and 5≦n' / (l+m+n)×100≦30 is satisfied. (5) The polyurethane elastic fiber according to any one of (1) to (4), wherein the portion of the general formula (1) has a number average molecular weight of 3,000 or more and 30,000 or less. (6) A polyurethane elastic fiber according to any one of (1) to (5), having a bio-based content of 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement according to ISO 16620-2. Effect of the Invention

[0016] According to the present invention, it is possible to provide a polyurethane elastic fiber which has high stress during shrinkage, i.e., high recovery stress, and excellent oxidation resistance and is highly durable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described in detail below with reference to the embodiments.

[0018] First, the polyurethane used in the polyurethane resin composition and polyurethane elastic fiber of the present invention will be described. The polyurethane described here is preferably used as a main component, and the main component here means a component contained in the polyurethane resin composition and polyurethane elastic fiber in an amount of more than 50 mass %.

[0019] The polyurethane used in the present invention has a polyether structure in its skeleton. The polyurethane having a polyether structure in its skeleton has a structure in which a polymer diol and a diisocyanate having a polyether structure are used as starting materials. Here, the term "having a structure in which a starting material is used" refers to the structure of the corresponding part of the starting material in order to explain the skeleton structure of the polymer, and the starting material and its synthesis method are not particularly limited. That is, for example, it may be a polyurethane urea made of a polymer diol, a diisocyanate, and a low molecular weight diamine as a chain extender, or it may be a polyurethane urethane made of a polymer diol, a diisocyanate, and a low molecular weight diol as a chain extender. In addition, it may be a polyurethane urea using a compound having a hydroxyl group and an amino group in the molecule as a chain extender. It is also preferable to use a polyfunctional glycol or isocyanate having a functionality of 3 or more within a range that does not interfere with the effects of the present invention. Furthermore, the processing method is not particularly limited. That is, it may be a polyurethane by recycling through remolding and re-spun yarn.

[0020] In the present invention, the polymer diol having a polyether structure is one in which the polyether structure satisfies the following general formula (1).

[0021] [ka]

[0022] (R 1 is an alkylene group having 2 to 6 carbon atoms, R 2 is an alkyl group having 1 to 2 carbon atoms, l, m, n satisfy 4≦n / (l+m+n)×100≦50) When l, m, and n in the general formula (1) satisfy the condition 6≦n / (l+m+n)×100≦16, the balance between the stress during elongation and the stress during elongation recovery is good, and the modified tetramethylene ether unit (CH2CH2CH2CHR 2 This is preferred because it is possible to obtain equivalent properties with fewer modified tetramethylene ether units compared to conventional techniques equivalent to (CH2CH2CHRCH2-O), such as (CH2CH2CHRCH2-O). In addition, in general formula (1), l, m, and n only represent the ratio. In other words, each unit is not limited to a block body having l, m, and n as repeating units, but may be a random body in which each unit is randomly linked.

[0023] In the general formula (1), -(CH2CH2CH2CHR 2 When the number of -O)n- at the terminals of the general formula (1) is n', if the relationship 5≦n' / (l+m+n)×100≦30 is satisfied, the balance between the stress during elongation and the stress during elongation recovery is better, and durability, i.e., resistance to thermal oxidative degradation, resistance to ultraviolet degradation, resistance to chlorine degradation, and the combined durability of these, due to the synergistic action with the nitrogen-containing aromatic compound, is improved, which is preferable. R 1 It is also preferable for the carbon number to be 2, 3, 5, or 6 other than 4. In the case of 2, water vapor permeability is increased, imparting moisture absorption and water absorption functions, while in the case of 6, hydrophobicity is imparted. In the odd-numbered carbon numbers of 3 and 5, crystallization of the soft segment during elongation (strain-induced crystallization) is suppressed, contributing to elongation recovery.

[0024] In addition, (CH2CH2CH2CH2-O) and (CH2CH2CH2CHR 2It is preferable that THF and 2-MeTHF, which are raw materials for the (-O) structural unit, are made from carbon-neutral biomass resource-derived components suitable for thermal recycling. In such a case, the degree to which components derived from biomass resources are used as raw materials is expressed as the bio-based ratio. The bio-based ratio can be obtained by ISO 16620-2, which is a method for measuring and identifying the concentration of radioactive carbon (carbon-14). In the present invention, the above-mentioned ISO 16620-2 method for measuring and identifying the concentration of radioactive carbon (carbon-14) may be simply referred to as carbon isotope ratio measurement. It is preferable that the polyurethane resin composition and polyurethane elastic fiber of the present invention have a bio-based ratio of 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement.

[0025] The other polymer diols preferably contain polyether-based, polyester-based diols, polycarbonate diols, etc. In particular, from the viewpoint of imparting flexibility and elongation to the molded article obtained from the polyurethane resin composition of the present invention and the polyurethane elastic fiber obtained from the polyurethane resin composition of the present invention, it is preferable to use polyether-based diols. In addition, two or more of these polymer diols may be mixed and used.

[0026] The molecular weight of the polymer diol is preferably 1,000 or more, more preferably 3,000 or more, in terms of obtaining elongation, strength, heat resistance, etc., when made into an elastic fiber. By using a polyol with a molecular weight in this range, an elastic fiber excellent in elongation, strength, and heat resistance can be obtained. In addition, the number average molecular weight is preferably 30,000 or less, more preferably 6,000 or less. By using a polyol with a molecular weight in this range, an elastic fiber excellent in elongation, elastic recovery force, heat resistance, and durability due to a synergistic effect with a nitrogen-containing aromatic compound can be obtained.

[0027] Next, as diisocyanates, aromatic diisocyanates such as diphenylmethane diisocyanate (hereinafter sometimes abbreviated as MDI), tolylene diisocyanate, 1,4-diisocyanate benzene, xylylene diisocyanate, and 2,6-naphthalene diisocyanate are particularly suitable for synthesizing polyurethanes with high heat resistance and strength. Furthermore, as alicyclic diisocyanates, for example, methylene bis(cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, and octahydro-1,5-naphthalene diisocyanate are preferred. Alicyclic diisocyanates can be effectively used in particular to suppress yellowing of molded articles obtained from the polyurethane resin composition of the present invention and polyurethane elastic fibers obtained from the polyurethane resin composition of the present invention. These diisocyanates may be used alone or in combination of two or more. Hereinafter, a molded article obtained from the polyurethane resin composition may be referred to as a polyurethane resin molded article.

[0028] The chain extender used in synthesizing the polyurethane is preferably at least one of low molecular weight diamines and low molecular weight diols, and may be one having both a hydroxyl group and an amino group in one molecule, such as ethanolamine.

[0029] Examples of preferred low molecular weight diamines include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p-xylylenediamine, m-xylylenediamine, p,p'-methylenedianiline, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, and bis(4-aminophenyl)phosphine oxide. It is preferable to use one or more of these. Ethylenediamine is particularly preferred. By using ethylenediamine, elastic fibers excellent in elongation, elastic recovery, and heat resistance can be easily obtained. A triamine compound capable of forming a crosslinked structure, such as diethylenetriamine, may be added to these chain extenders to an extent that the effect is not lost.

[0030] Representative examples of low molecular weight diols include ethylene glycol, 1,3 propanediol, 1,4 butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, and 1-methyl-1,2-ethanediol. It is preferable to use one or more of these. Ethylene glycol, 1,3 propanediol, and 1,4 butanediol are particularly preferable. When these are used, the heat resistance of the diol-extended polyurethane is increased, and a polyurethane resin molded body and elastic fiber having higher strength can be obtained.

[0031] In the present invention, the molecular weight of the polyurethane is preferably in the range of 30,000 to 150,000 in terms of number average molecular weight, from the viewpoint of obtaining a polyurethane resin molded product and polyurethane elastic fiber having high durability and strength. The molecular weight is measured by GPC and converted into polystyrene.

[0032] It is also preferable to use one or more kinds of terminal blocking agents in the polyurethane in combination. Examples of the terminal blocking agent include monoamines such as dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, and diamylamine, monools such as ethanol, propanol, butanol, isopropanol, allyl alcohol, and cyclopentanol, and monoisocyanates such as phenylisocyanate.

[0033] The polyurethane resin composition and polyurethane elastic fiber of the present invention contain a nitrogen-containing aromatic compound in an amount of 0.05% by mass or more and 2.0% by mass or less, and exhibit synergistic durability with the polyurethane having the polyether structure of the general formula (1) in the skeleton, particularly high durability with excellent oxidation resistance.

[0034] [ka]

[0035] (R 1 is an alkylene group having 2 to 6 carbon atoms, R 2 is an alkyl group having 1 to 2 carbon atoms, l, m, n satisfy 4≦n / (l+m+n)×100≦50) If the content of the nitrogen-containing aromatic compound is less than 0.05% by mass, the durability of the polyurethane resin molded body and the polyurethane elastic fiber may be insufficient, and if it exceeds 2.0% by mass, the heat resistance of the polyurethane resin molded body and the polyurethane elastic fiber may decrease significantly, and the yellowing resistance may decrease.

[0036] The value of 0.05% by weight or more and 2.0% by weight or less of the content of the nitrogen-containing aromatic compound generally corresponds to the presence of the nitrogen-containing aromatic compound in the range of 0.25 to 13.3 milliequivalents (meq / kg) in 1 kg of elastic fiber. On the other hand, since aromatic rings containing nitrogen atoms are prone to thermal decomposition, when the content of the nitrogen-containing aromatic compound is too high (i.e., when the amount of aromatic ring nitrogen atoms exceeds 13.3 milliequivalents), the radical generation due to thermal decomposition becomes dominant over the synergistic effect with the polyurethane having the polyether structure of general formula (1) in the skeleton, and the heat resistance is reduced or a quinone structure is formed, causing thermal discoloration, so that functions such as high heat resistance cannot be obtained. In addition, although there are cases where a large amount of the nitrogen-containing aromatic compound is contained as a light resistance agent, when the content is so high that it exceeds 2.0 mass%, the effect of high heat resistance, which is the object of the present invention, cannot be obtained. From these viewpoints, it is preferable that the content of the nitrogen-containing aromatic compound is not too high, but is an appropriate amount, and the preferred range is from 0.1% by mass to 1.0% by mass, and further from 0.2% by mass to 0.8% by mass.

[0037] Furthermore, the polyurethane having the polyether structure of the general formula (1) in the skeleton thereof may be -(CH2CH2CH2CHR 2 When the number of terminals of -O)n- is n', it is preferable that 5≦n' / (l+m+n)×100≦30 is satisfied. In such a case, the antioxidant effect with the nitrogen-containing aromatic compound can be exerted synergistically. Also, it is more preferable that 10≦n' / (l+m+n)×100≦15, and the nitrogen-containing aromatic compound is effective even in a smaller amount. In such a case, it is also preferable that the content of the nitrogen-containing aromatic compound is 0.1 mass% or more and 0.6 mass% or less.

[0038] More specifically, the nitrogen-containing aromatic compounds contained therein are compounds having a nitrogen-containing aromatic heterocycle in which a nitrogen atom is arranged in an aromatic ring in the molecule. Examples of chemical structural skeletons include pyrrole, pyridine, carbazole, and quinoline having one nitrogen aromatic heterocycle, imizazole, pyrazole, pyridazine, pyrazine, pyrimidine, naphthyridine, and phenanthroline having two nitrogen aromatic heterocycles, and triazine, benzotriazole, and naphthyridine having three nitrogen aromatic heterocycles. Heteroatoms other than nitrogen may also be arranged, such as benzothiazole and benzoxazole. Specific examples of such nitrogen-containing aromatic compounds include benzotriazole compounds and triazine compounds known as ultraviolet absorbents, and more specific examples include 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-bisphenyl)benzotriazole, 2,4-di(2′,4′-dimethylphenyl)-6-(2″-hydroxy-4″-alkoxyphenyl)-1,3,5-triazine, and 2,2′-(1,4-phenylene)bis[4H-3,1-benzaxazin-4-one]. Examples of such products by trade name include "TINUVIN"-P, "TINUVIN"-213, "TINUVIN"-234, "TINUVIN"-327, "TINUVIN"-328, "TINUVIN"-571, and "TINUVIN"-1577 manufactured by Ciba-Geigy Corporation, "Sumisorb" 250 manufactured by Sumitomo Chemical Co., Ltd., "Cyasorb" UV-5411, UV-1164, and UV-3638 manufactured by American Cyanamid Co., Ltd., and "ADK STAB" LA-31 manufactured by Asahi Denka Kogyo Co., Ltd. In order to obtain a polyurethane elastic fiber that exhibits high heat resistance during dyeing, resistance to unsaturated fatty acids, and resistance to heavy metals, as well as high elastic recovery and high strength and elongation, the content of the nitrogen-containing aromatic compound must be 0.05% by weight or more and 2.0% by weight or less. Among the nitrogen-containing aromatic compounds, compounds with a molecular weight of 300 or more are preferred from the viewpoint of suppressing the volatilization loss during spinning. From the viewpoint of improving the heat resistance and spinnability during dyeing, it is more preferred to use a compound having two or more nitrogen atoms in the aromatic ring, which is presumably because it is easy to form a complex with a heavy metal and exerts a chelating effect. Furthermore, in order to fully exert the effect, it is preferable that the chemical structure skeleton of the nitrogen-containing aromatic compound is triazine. It is preferable to test in advance the molecular weight of the nitrogen-containing aromatic compound actually used, the effective number of nitrogen in the aromatic ring, and the purpose of use, and appropriately determine the optimal value. In order to obtain polyurethane elastic fibers having particularly high heat resistance during dyeing, 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-1,3,5-triazine is preferred as the nitrogen-containing aromatic compound. Furthermore, the compound used as the nitrogen-containing aromatic compound is preferably a liquid compound having a viscosity of 100 cP or more and 10,000 P or less at 20°C, from the viewpoints of accelerating dispersion and dissolution in polyurethane, imparting desired properties to the polyurethane elastic fiber produced, and enabling the polyurethane elastic fiber to have an appropriate degree of transparency, and further, preventing a decrease in the content of these compounds even when exposed to heat or the like during the spinning process, and preventing discoloration or yellowing of the polyurethane elastic fiber. Furthermore, the polyurethane used in the present invention is preferably one in which one or more types of terminal blocking agents are used in combination. Preferred terminal blocking agents include monoamines such as dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, and diamylamine, monools such as ethanol, propanol, butanol, isopropanol, allyl alcohol, and cyclopentanol, and monoisocyanates such as phenylisocyanate. In the present invention, the polyurethane elastic fiber or polyurethane spinning solution may contain various stabilizers other than those mentioned above, such as hindered phenol-based, sulfur-based, phosphorus-based, etc. antioxidants, hindered amine-based, triazole-based, benzophenone-based, benzoate-based, nickel-based, salicylic acid-based, etc. light stabilizers, antistatic agents, lubricants, molecular regulators such as peroxides, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, fluorescent whitening agents, fillers, flame retardants, flame retardant assistants, pigments, etc., within the range that does not impair the effects of the present invention. For example, it is preferable that the light fasteners and antioxidants include 2,6-di-t-butyl-p-cresol (BHT) and benzophenone-based agents, various hindered amine-based agents, various pigments such as iron oxide and titanium oxide, inorganic substances such as zinc oxide, cerium oxide, magnesium oxide, and carbon black, fluorine-based or silicone-based resin powder, metal soaps such as magnesium stearate, bactericides, deodorants, and antibacterial agents containing silver, zinc, or their compounds, lubricants such as silicone and mineral oil, and various antistatic agents such as barium sulfate, cerium oxide, betaine, and phosphoric acid, and it is also preferable to react these with the polymer. In order to further increase the durability to light and various nitrogen oxides, it is also preferable to use nitrogen oxide scavengers such as HN-130 and HN-150 manufactured by Japan Finechem Co., Ltd. From the viewpoint of facilitating an increase in the spinning speed in the dry spinning process, fine particles of metal oxides such as titanium dioxide and zinc oxide may be added to the spinning dope. From the viewpoint of improving heat resistance and functionality, inorganic substances and inorganic porous substances (e.g., bamboo charcoal, wood charcoal, carbon black, porous mud, clay, diatomaceous earth, coconut shell activated carbon, coal-based activated carbon, zeolite, perlite, etc.) may be added within a range that does not impair the effects of the present invention. These additives may be added when preparing a spinning dope by mixing the polyurethane solution with the above-mentioned modifier, or may be contained in the polyurethane solution or dispersion before mixing. The content of these additives is appropriately determined depending on the purpose, etc.

[0039] In the polyurethane elastic fiber of the present invention, when an antioxidant is contained, it is preferable that the content is 0.002% by mass or more and 5.0% by mass or less. When the content of the antioxidant is within this range, the polyurethane elastic fiber has practically preferable properties, and particularly preferable antioxidants are hindered phenol compounds, and examples of the phenol compounds generally known as antioxidants include the above-mentioned.For example, 3,5-di-t-butyl-4-hydroxy-toluene, n-octadecyl-β-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 1,3,5-trimethyl-2,4,6'-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, calcium (3,5-di-t-butyl-4-hydroxy-benzyl-monoethyl-phosphate), triethylene glycol-bis[3-( 3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, tocopherol, 2,2'-ethylidenebis(4,6-di-t-butylphenol), N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidobis[ethyl-3-(3,5-di-t-butyl-4 -hydroxyphenyl)propionate], 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, ethylene-1,2-bis(3,3-bis[3-t-butyl-4-hydroxyphenyl]butyrate), ethylene-1,2-bis(3-[3-t-butyl-4-hydroxyphenyl]butyrate), 1,1-bis(2-methyl-5-t-butyl-4-hydroxyphenyl)butane, 1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butane, 1,3,5-tris(3',5'-di-t-butan and 1,3,5-tris(3'-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3'-t-butyl-4'-hydroxy-5-methylbenzyl)-S-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and further, high molecular weight hindered phenol compounds known as antioxidants for polyurethane elastic fibers are also preferably used.

[0040] Specific examples of preferred high molecular weight hindered phenol compounds include addition polymers of divinylbenzene and cresol, addition polymers of dicyclopentadiene and cresol, isobutylene adducts, and polymers of chloromethylstyrene and compounds such as cresol, ethylphenol, and t-butylphenol. Here, divinylbenzene and chloromethylstyrene may be p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be any of o-, m-, and p-.

[0041] Among these, from the viewpoints of stabilizing the viscosity of the raw material spinning solution for polyurethane elastic fiber, suppressing volatilization loss during spinning, and obtaining good spinnability, a compound with a molecular weight of 300 or more is preferred. Furthermore, in order to efficiently exhibit a high spinning speed, heat resistance during dyeing, resistance to unsaturated fatty acids, and resistance to heavy metals, it is preferred to use any one of 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], ethylene-1,2-bis(3,3-bis[3-t-butyl-4-hydroxyphenyl]butyrate), and an adduct of divinylbenzene and p-cresol having a repeat number of 6 to 12, or a combination of these. Among them, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is particularly preferred. In addition, when triazine compounds are selected as compound (a) and compound (c), a particularly high synergistic effect can be obtained in terms of heat resistance during dyeing. Among them, it is particularly preferred that compound (a) is 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and compound (c) is 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-1,3,5-triazine.

[0042] Furthermore, from the viewpoint of suppressing deterioration of various durability properties due to oxidation, such as heat resistance, composite durability, light resistance, and yellowing, the polyurethane elastic fiber of the present invention preferably contains a singly hindered phenol compound. The singly hindered phenol compound is preferably a compound containing at least two singly hindered hydroxyphenyl groups and having a skeleton selected from bisester and alkylidene. Here, it is more preferable that the alkyl group present at the ring position adjacent to the hydroxyl group in the hydroxyphenyl group is a tertiary butyl group, and it is even more preferable that the equivalent weight of the hydroxyl group is 600 or less.

[0043] Furthermore, the phenol compound in the present invention is preferably a singly hindered phenol compound. For example, a singly hindered phenol compound is preferably ethylene-1,2-bis(3,3-bis[3-t-butyl-4-hydroxyphenyl]butyrate) (chemical formula 1 below) having a structure in which a singly hindered hydroxyphenyl group is covalently bonded to a bisester skeleton.

[0044] [ka]

[0045] By incorporating the above-mentioned one-hindered phenol compound, The effect of suppressing the deterioration of properties can be improved. This type of hindered phenol compound is effective in suppressing the molecular weight of polyurethane constituting polyurethane elastic fiber, specifically in the case of underwear and other items that are frequently washed and bleached. In order to obtain this effect sufficiently and not adversely affect the physical properties of the fiber, the content of the single hindered phenol compound is preferably 0.15 to 4 mass % of the polyurethane elastic fiber, more preferably 0.5 to 3.5 mass %, and the breaking strength and elongation, composite durability, yellowing resistance, and light resistance in some cases are ensured. The content of the antioxidant is more preferably in the range of 0.2 mass % to 3.0 mass %, and even more preferably in the range of 0.5 mass % to 2.0 mass %.

[0046] The content of the antioxidant in the polyurethane elastic fiber is preferably in the range of 0.1% by mass to 5.0% by mass. When the content of the antioxidant in the polyurethane elastic fiber is within this range, the content of the antioxidant contained in the polyurethane elastic fiber finally produced can be easily controlled to the desired content of the antioxidant described above. The content of the antioxidant in the polyurethane elastic fiber is more preferably in the range of 0.2% by mass to 3.0% by mass, and even more preferably in the range of 0.5% by mass to 2.0% by mass.

[0047] The antioxidant contained is more specifically a hindered phenol compound having a molecular weight of 1000 or more, and it is preferable to use a hindered phenol compound having a molecular weight of 1,000 or more, which is known as an antioxidant for polyurethane elastic fibers. There is no particular restriction other than the relatively high molecular weight of 1,000 or more, and preferred examples of such high molecular weight hindered phenol compounds include addition polymers of divinylbenzene and cresol, addition polymers of dicyclopentadiene and cresol, isobutylene adducts, and polymers of chloromethylstyrene and compounds such as cresol, ethylphenol, and t-butylphenol. Here, divinylbenzene and chloromethylstyrene may be p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be any of o-, m-, and p-.

[0048] Among them, from the viewpoint of stabilizing the viscosity of the raw material spinning solution of the polyurethane elastic fiber and obtaining good spinnability, a polymer hindered phenol compound derived from cresol is preferable. Furthermore, in order to efficiently exhibit a high spinning speed, heat resistance during dyeing, resistance to unsaturated fatty acids, and resistance to heavy metals, it is preferable to contain the high molecular weight hindered phenol compound to a certain extent, but from the viewpoint of obtaining better basic physical properties as a polyurethane elastic fiber, it is preferable that the amount is not too much.

[0049] In the polyurethane elastic fiber of the present invention, the content of the decomposition products of the antioxidant as described above is also preferably restricted to 1.0% by mass or less. When the content of the decomposition products of the antioxidant is within this range, the polyurethane elastic fiber has practically preferable properties, particularly preferable breaking strength and elongation, color fastness, and durability. The content of the decomposition products of the antioxidant is preferably in the range of 1.0% by mass or less, more preferably in the range of 0.5% by mass or less.

[0050] In the polyurethane elastic fiber of the present invention, when a tertiary amine compound is contained, the content is preferably 0.2% by mass or more and 5.0% by mass or less. When the content of the tertiary amine compound is within this range, the practically preferable properties of the polyurethane elastic fiber, such as spinnability, dyeability, durability, and yellowing resistance, are improved.

[0051] The tertiary amine compound used in the present invention is not particularly limited as long as it has an amino group in its structure. From the viewpoint of the chlorine deterioration resistance and yellowing of the polyurethane elastic fiber, however, among the primary to tertiary amino groups, those having only tertiary amino groups in the molecule are particularly preferred.

[0052] If the number average molecular weight of the tertiary amine compound is less than 2,000, it will fall off due to rubbing against guides or knitting needles during knitting of polyurethane elastic fiber, or will flow out during processing in a bath such as dyeing, resulting in poor water repellency, so the number average molecular weight must be 2,000 or more. In consideration of solubility in polyurethane spinning dope, the number average molecular weight is preferably in the range of 2,000 to 10,000, and more preferably in the range of 2,000 to 4,000.

[0053] The inclusion of the above-mentioned tertiary amine compound can improve the performance of the polyurethane elastic fiber, particularly the yellowing prevention performance. In order to obtain this effect sufficiently and not to adversely affect the physical properties of the fiber, the tertiary amine compound is preferably contained in an amount of 0.2% by mass or more and 5.0% by mass or less, more preferably 0.5% by mass or more and 4.0% by mass or less, based on the fiber mass. The more preferred content of the tertiary amine compound is in the range of 0.5% by mass or more and 3.0% by mass or less, and even more preferably 0.5% by mass or more and 2.0% by mass or less.

[0054] More specifically, the tertiary amine compounds contained therein include linear polymeric compounds having a number average molecular weight of 2000 or more obtained by the reaction of t-butyldiethanolamine with methylene-bis-(4-cyclohexylisocyanate), polyethyleneimine, and high molecular weight compounds having a branched structure containing a primary amino group, a secondary amino group, and a tertiary amino group in the molecular skeleton.

[0055] In the polyurethane elastic fiber of the present invention, the content of the decomposition products of the tertiary amine compounds as described above is also preferably restricted to 1.0% by mass or less. When the content of the decomposition products of the tertiary amine compounds is within this range, the practically preferred properties of the polyurethane elastic fiber, particularly the preferred wound yarn shape, composite durability, and yellowing resistance, are ensured. The content of the decomposition products of the tertiary amine compounds is more preferably in the range of 1.0% by mass or less, and even more preferably in the range of 0.5% by mass or less.

[0056] In the polyurethane elastic fiber of the present invention, when a crosslinking structure regulator is contained, it is preferable that the crosslinking structure regulator is contained in an amount of 0.002% by mass or more and 2.0% by mass or less. The crosslinking structure regulator is an agent that is added after the polymerization terminator for polyurethane is added and polymerization is completed. When the content of the crosslinking structure regulator is within this range, practically preferable properties of polyurethane elastic fiber, particularly preferable breaking strength and elongation, permanent set rate, and yellowing resistance, are ensured. The content of the crosslinking structure regulator is more preferably in the range of 0.02% by mass or more and 1.5% by mass or less, and even more preferably in the range of 0.2% by mass or more and 1.0% by mass or less.

[0057] The crosslinking structure regulator contained therein may include monoamines and / or diamines. More specifically, the monoamines may include dimethylamine, diethylamine, cyclohexylamine, etc., and the diamines may include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, and 2-methylpentamethylenediamine. Particularly preferred is the mixed use of monoamines and diamines.

[0058] It is effective to do so. As an index for this, it is preferable to blend polyurethane having a number average molecular weight based on gel permeation chromatography (GPC) of 20,000 or more and 120,000 or less, and no peak or shoulder in the detection intensity curve in the region of the molecular weight based on GPC of 30,000 or less. In consideration of the breaking strength and elongation of polyurethane elastic fiber, the number average molecular weight is preferably in the range of 30,000 or more and 100,000 or less. More preferably, it is in the range of 40,000 or more and 80,000 or less. The detection intensity curve is a differential molecular weight distribution curve (horizontal axis is molecular weight, vertical axis is the value obtained by differentiating the concentration fraction by the logarithm of the molecular weight), and the shoulder is a shoulder peak.

[0059] In the present invention, the molecular weight of the polyurethane elastic fiber is preferably in the range of 10,000 to 50,000 in terms of number average molecular weight when a tertiary amine compound having a number average molecular weight in the range of 2,000 to 10,000 or a preferably used antioxidant having a molecular weight of 1,000 or more is blended. The molecular weight is measured by GPC and converted into polystyrene. Next, the method for producing the 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. The method for producing the polyurethane solution and the polyurethane, which is the solute in the solution, may be either the melt polymerization method or the solution polymerization method, or other methods. However, the solution polymerization method is more preferable. In the case of the solution polymerization method, the polyurethane is less likely to produce foreign matter such as gel, making it easy to spin and easy to produce polyurethane elastic fibers with low fineness. In addition, the solution polymerization method has the advantage that the operation of making a solution can be omitted. The polyurethane elastic fiber of the present invention can be used in various applications, such as pantyhose, brassieres, slips, camisoles, bodysuits, shorts, girdles, tightening strings for socks and pants, swimwear, training wear, yoga wear, mountaineering clothes, work clothes, fireworks clothes, men's and women's suits and other clothing used in combination with natural short fibers, wetsuits, leak-proof tightening members for sanitary products such as disposable diapers, artificial skin, artificial blood vessels, artificial hearts, electrical insulation materials, wiping cloths, copy cleaners, gaskets, tightening members for safety clothing, tightening members for laboratory coats, tightening members for waterproof materials, bandages, tightening members for gloves, etc., that is, it can be used suitably in areas where elastic stretching force is required. EXAMPLES

[0060] (Examples 1 to 18, Comparative Examples 1 to 10) The production and evaluation of polyurethane elastic fibers and elastic fibers to which a nitrogen-containing aromatic compound has been added will be described below for Examples 1 to 18 and Comparative Examples 1 to 10 shown in Tables 1 to 4. [Comparative Example 1] In Comparative Example 1, which is a conventional technique, 87.5 mol of dehydrated tetrahydrofuran and 4.0 mol of dehydrated 3-methyl-tetrahydrofuran were charged into a reactor equipped with a stirrer, and a polymerization reaction was carried out for 8 hours under a nitrogen blanket at a temperature of 10°C in the presence of a catalyst (a mixture of 70% by weight of perchloric acid and 30% by weight of acetic anhydride). The reaction liquid was neutralized with an aqueous sodium hydroxide solution to obtain a copolymerized tetramethylene ether diol having a number average molecular weight of 3,500 (containing 4.0 mol % of structural units (a) derived from 3-methyl-tetrahydrofuran). This copolymerized tetramethylene ether diol was used as the polyalkylene ether diol.

[0061] The copolymerized tetramethylene ether diol was charged in a vessel at 1.97 moles of 4,4'-MDI per mole, and reacted at 90°C. The resulting reaction product was thoroughly stirred in N,N-dimethylacetamide (DMAc) to dissolve, obtaining a solution. Next, a DMAc solution containing 60 mole % ethylenediamine (EDA) and 40 mole % 1,2-propanediamine (1,2-PDA) as a chain extender was added to the solution in which the reactants were dissolved, and a DMAc solution containing diethylamine as an end-capping agent was further added to prepare a polyurethane urea solution with a polymer solid content of 25 wt %. The resulting solution had a viscosity of about 2400 poise at 40°C. The polymer had an intrinsic viscosity of 0.90 when measured at 25°C in DMAc at a solution concentration of 0.5 g / 100 ml.

[0062] This polyurethane urea solution was extruded from the spinneret into a high-temperature (350°C) inert gas (nitrogen gas) in four filaments, dried by passing through this high-temperature gas, passed through an air jet twisting machine so that the yarn in the middle of drying was twisted together, the four filaments were bonded together, and wound up at a speed of 540 m / min to produce a polyurethane urea fiber of 44 dtex by bonding the four filaments together. The glass transition point (Tg) was -74°C. The polyurethane urea constituting this polyurethane urea fiber had a urethane group concentration of 0.49 mol / kg and an effective terminal amine concentration of 18 meq / kg.

[0063] Next, a 1:1 (mass ratio) mixture of polyurethane (DuPont's "Methachlor" (registered trademark) 2462) produced by the reaction of t-butyldiethanolamine with methylene-bis-(4-cyclohexylisocyanate) and a condensation polymer of p-cresol and divinylbenzene (DuPont's "Methachlor" (registered trademark) 2390) was used as an antioxidant, and a DMAc solution (35 mass%) of this mixture was prepared to serve as additive solution (B).

[0064] The above solution PUUX1, the additive solution (B), and the nitrogen-containing aromatic compound (C) were uniformly mixed at 99 mass %, 1.0 mass %, and 0.2 mass %, respectively, and temporarily prepared as a spinning solution (D).

[0065] Using the spinning solution thus obtained, dry spinning was performed at a dry nitrogen temperature of 300°C or higher so that the DMAc in the spinning solution and the floating ethylenediamine were 1 / 100 or less of the spinning solution content. At this time, the speed ratio of the godet roller and the winder was set to 1:1.20, and a multifilament polyurethane elastic fiber of 22 dtex / 3fil was spun, and a treatment agent (oil agent) described later was roller-lubricated by an oiling roller before winding, and the winding speed was 600 m / min, and the fiber was wound on a cylindrical paper tube of 58 mm in length via a traverse guide that gave a winding width of 38 mm using a surface drive winder, to obtain a dry spun polyurethane elastic fiber as a wound yarn of 500 g. The obtained polyurethane elastic fiber was a fused yarn in which three filaments were fused together. The rotation speed of the oiling roller was adjusted so that the amount of the treatment agent applied was a predetermined amount relative to the yarn. The amount of the treatment agent applied was measured using n-hexane as an extraction solvent in accordance with JIS-L1073 (synthetic fiber filament yarn test method). The composition of the treatment agent used here was 1×10 -5 m 2 80 parts by weight of polydimethylsiloxane having a viscosity of 1.2 × 10 / s at 25 °C -5 m 2 The mixture is 15 parts by mass of a mineral oil having a viscosity of 1.0 g / s and 5 parts by mass of magnesium distearate having an average particle size of 0.5 μm.

[0066] [Example 1] A polyurethane urea fiber of 44 dtex was produced in the same manner as in Comparative Example 1, except that 2-methyl-tetrahydrofuran was used instead of 3-methyl-tetrahydrofuran. The glass transition point (Tg) was -70°C. The polyurethane urea constituting this polyurethane urea fiber had a urethane group concentration of 0.49 mol / kg and an effective terminal amine concentration of 20 meq / kg.

[0067] [Examples 2 to 5] As shown in Table 1, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that the concentration of 2-methyl-tetrahydrofuran in the copolyether polyol was changed.

[0068] [Comparative Examples 2-5] As shown in Table 1, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that only the concentration of 3-alkyltetrahydrofuran in the copolyether polyol was changed.

[0069] [Examples 6 to 10] As shown in Table 2, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that the content of the nitrogen-containing aromatic compound in the polyurethane elastic fiber was changed based on Example 2. [Comparative Examples 6 to 10] As shown in Table 2, based on Comparative Example 4, only the content of the nitrogen-containing aromatic compound in the polyurethane elastic fiber was changed, and a polyurethane urea fiber of 44 dtex was produced in the same manner as in Example 2.

[0070] [Examples 11 to 13] As shown in Table 3, based on Example 7, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that the secondary hydroxyl group concentration in the copolyether polyol was changed.

[0071] [Examples 14 to 16] As shown in Table 4, based on Example 7, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that only the number average molecular weight of the copolyether polyol was changed.

[0072] [Examples 17 and 18] As shown in Table 4, based on Example 7, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that the bio-content rate was changed.

[0073] As can be seen from Table 1, the mechanical properties such as stress at 200% elongation recovery exhibit the same effect when the copolymerization molar concentration of 2-methyl-tetrahydrofuran is half that of 3-methyl-tetrahydrofuran. As can be seen from Table 2, the heat resistance of the 2-methyl-tetrahydrofuran system is maximized when the amount of nitrogen-containing aromatic compounds is around 0.6. This does not happen in the 3-methyl-tetrahydrofuran system, but rather attenuates. The concentration of 2-tetrahydrofuran in the copolyether polyol was set to 8, and the concentration of 3-tetrahydrofuran in the copolyether polyol was set to 16. This is because the mechanical properties such as the stress at 200% elongation recovery show similar values. As can be seen from Table 3, the concentration of secondary hydroxyl groups in the 2-methyl-tetrahydrofuran system affects both the recovery stress and durability. As can be seen from Table 4, the number average molecular weight of the copolyether polyol in the 2-methyl-tetrahydrofuran system affects both the recovery stress and durability. Also, Example 17 is (CH2CH2CH2CHR 2 For the 2-MeTHF used as the raw material for the (CH2CH2CH2CH2-O) structural unit, 2-MeTHF synthesized from hemicellulose via D-xylol and furfural was used in order to use a carbon-neutral biomass resource-derived component suitable for thermal recycling. Furthermore, in Example 18, THF synthesized from hemicellulose via D-xylol and furfural was also used as the raw material for the (CH2CH2CH2CH2-O) structural unit. As a result, the performance was equal to or better than that of Example 7, which used a petrochemical-origin raw material. In Tables 1 to 4, the content is a value relative to 100 parts by mass of polymer solid content in the spinning dope. Next, the dry-spun polyurethane elastic fiber obtained above (hereinafter, sample yarn) was subjected to the following evaluations.

[0074] <Elongation at break, strength at break, permanent set rate, stress relaxation rate> The breaking elongation, breaking strength, permanent set rate and stress relaxation rate were measured by subjecting the polyurethane elastic fiber to a tensile test using an Instron 5564 tensile tester.

[0075] A sample with a length of 5 cm (L1) was stretched 300% five times at a tensile speed of 50 cm / min. The stress at 200% elongation is (G+200), The stress at 300% elongation was defined as (G1). Next, the length of the sample was held at 300% elongation for 30 seconds, and the stress after holding for 30 seconds was determined as (G2). The sample is then allowed to recover its elongation, The stress at 200% elongation and recovery is (G-200). The length of the sample when the stress became 0 was defined as (L2). This cycle of 300% stretching, holding and recovery was repeated until the sample broke at the sixth stretch. The stress at break was (G3) and the sample length at break was (L3). Hereinafter, the above properties are calculated by the following formula.

[0076] Breaking strength (cN) = (G3) 20 or more: ◎, 17 to less than 20: 〇, 14 to less than 17: △, less than 14: × Breaking elongation (%) = 100 × ((L3)-(L1)) / (L1) 480 or more: ◎, 460 to less than 480: 〇, 430 to less than 460: △, less than 430: × Stress at 200% elongation (cN) = (G+200) 1.2 or more but less than 1.4: ◎, 1.4 or more but less than 1.5: 〇, 1.5 or more but less than 1.6: △, over 1.6: × Stress at 200% elongation recovery = (G-200), 1.2 or more: ◎, 1.0 or more but less than 1.2: 〇, 0.8 or more but less than 1.0: △, less than 0.8: × Permanent distortion rate (%)=100×((L2)-(L1)) / (L1) Less than 20: ◎, 20 to 22: 〇, 22 to 24: △, 24 or more: × Stress relaxation rate (%) = 100 × ((G1)-(G2)) / (G1) Under 25: ◎, 25 to 28: 〇, 28 to 31: △, 31 or more: ×.

[0077] <Heat resistance> A two-way half tricot consisting of 85% by weight of nylon filament (24 dtex, 7 filaments) and 15% by weight of polyurethane elastic fiber (44 dtex) with an on-machine well count of 9 / inch and an on-machine course count of 18 / inch was produced by a conventional knitting method to produce a raw knitted fabric.

[0078] The obtained raw knitted fabric was preset under conditions of 170°C, 60 seconds, and 3% elongation, 0.1 ml of chemical 1 was applied, and then (almost simultaneously or within 1 minute) 0.1 ml of chemical 2 was applied, followed by dry heat treatment (175°C, 60 seconds of dry heat treatment, then removed and cooled to room temperature, then dry heat treatment at 180°C, 60 seconds), and then subjected to a bending tester at a maximum elongation of 20% in both vertical and horizontal directions, 2 times / second. Chemical 1 was a mineral oil-based nylon spinning oil containing 1% oleic acid. Chemical 2 was an aqueous solution of copper acetate (copper concentration 100 ppm). The raw knit fabric to which agent 1 and agent 2 had been applied in this manner was a model that reproduced the nylon-based stretch raw knit fabric before dyeing, which has trace amounts of machine oil (containing metals) and nylon spinning oil adhering thereto during knitting. The amount of agent 1 adhered to 0.9 g of raw knit fabric was 3.0 mg, and the amount of agent 2 adhered thereto was 3.0 mg. The resulting stretch fabric was dyed by a conventional method.

[0079] The degree of damage to the polyurethane tissue in the obtained dyed stretch fabric was observed visually or under magnification, and judged according to the following criteria. The judgement was made by five people, and the mode (the judgement that occurred most frequently) was used. When the judgements were split between two people, two people, and one person, the judgement was given as "△". ◎: No damage, and the knitting structure is uniform. ○: No damage. △: The fabric is worn and dented, and under magnification the polyurethane elastic fibers are brittle. ×: There is a hole in the fabric.

[0080] <Lightfastness, yellowing resistance, composite durability> After the following exposure treatments (a), (b), and (c), the respective characteristics were determined as follows. Lightfastness The sample yarn was subjected to the following exposure treatment (a) while being stretched to 100%, and the retention rate of breaking strength thereafter was determined. Yellowing The yellowing was evaluated based on the degree of yellowing (hereinafter abbreviated as Δb) after the samples were exposed to the light (a) and (b). The degree of yellowing was calculated as follows: Δb = b value after exposure treatment - b value before exposure treatment Measurement of Yellowing Property The sample form and measurement were carried out as follows. The sample yarn was wound around a 5 x 5 cm sample plate with a minimum load so tightly that the color of the sample plate would not be affected, and used as a sample. The front of the sample and the common standard white surface (JIS Z 8722 4.3.4) were covered with a homogeneous, flat, transparent glass plate of about 1 mm in thickness. The b value was measured according to JIS L 1013 C method (Hunter's method) using a Hunter type color difference meter and calculated based on the following formula. The measurement was performed five times, and the average value was used. b=7.0(Y-0.847Z) / Y 1 / 2 (X, Y, and Z are calculated according to JIS Z 8701) ·Composite durability The sample yarn was subjected to the following exposure treatments (a), (b), and (c) while being stretched to 100%, and the retention rate of breaking strength thereafter was determined.

[0081] Each exposure treatment was carried out as follows. (A) Ultraviolet (UV) exposure treatment Using a carbon arc type weather meter manufactured by Suga Test Instruments Co., Ltd., the samples were exposed to a temperature and humidity of 63°C and 60% RH for 25 hours. (a) Nitrogen oxide (NOx) exposure treatment Using a closed container (Scott Tester) with a rotating sample stand, the samples were exposed to 10 ppm NO2 gas at 40°C and 60% RH for 20 hours. (c) Chlorine bleach (Cl2) exposure treatment The sample was exposed to a 500 ppm aqueous solution of "Kao Haiter" manufactured by Kao Corporation in a thermostatic chamber at 40°C for 30 minutes, and then washed with water for 10 minutes. This cycle was repeated eight times.

[0082] The criteria for judgment are as follows: Lightfastness 80% or more is ◎, 60% to less than 80% is 〇, 40% to less than 60% is △, and less than 40% is × ·Yellow discoloration Less than 3 is ◎, 3 to 6 is 〇, 6 to 10 is △, 10 or more is × ·Composite durability 60% or more is ◎, 40% to less than 60% is 〇, 20% to less than 40% is △, and less than 20% is × <Molecular weight> The molecular weight measurement by GPC was carried out under the following conditions. Column: Showa Denko SHODEX KF-806M (2 pieces) Solvent: N,N-dimethylacetamide 1ml / min Temperature: 40℃ Detector: Differential refractometer (RI detector) <Bio-based rate> The biomass ratio (mass%) was measured using ISO 16620-2, a method for measuring and identifying the concentration of radioactive carbon (carbon-14).

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

[0086] [Table 4]

[0087] The tensile strength at break, elongation at break, residual strain rate and thermal softening point of the polyurethane resin measured by the following methods using the same polyurethane urea solutions used for spinning in Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 5.

[0088] The polyurethane resin solution was applied to a thickness of 1.0 mm on a release-treated glass plate, dried in a circulating air dryer at 70°C for 3 hours, and then peeled off from the glass plate to produce a film approximately 0.2 mm thick. [2] Measurement method for film strength and elongation The film obtained above was left to stand for one day in a room adjusted to a temperature of 25°C and a humidity of 65%RH, and then the tensile strength at break and elongation at break were measured according to JIS K 6251. The larger these values ​​are, the better the properties as an elastic fiber are. The thickness of the parallel part of the dumbbell-shaped test piece is 200 μm, the width of the parallel part is 5 mm, and the initial gauge length is 20 mm. [3] Residual distortion measurement method A rectangular test piece measuring 100 mm long x 5 mm wide was cut out from the film obtained above, and a mark was made so that the distance between the marks was 50 mm. This test piece was set in the chuck of an Instron tensile tester (Shimadzu Corporation, Autograph) and stretched at a constant speed of 500 mm / min in an atmosphere of 25°C until the distance between the marks reached 300%, and then immediately returned to the distance between the chucks before stretching at the same speed.

[0089] The distance between the gauge marks after the above-mentioned operation (D1) was measured, and the residual strain rate (%) was calculated using this value and the distance between the gauge marks before the test (D0 = 50 mm) according to the following formula.

[0090] Residual distortion rate (%) = {(D1-D0) / D0} x 100 [4] Thermal softening point measurement method A test piece measuring 10 mm in length and 10 mm in width was cut out from the film obtained above, and the sample was heated from room temperature to 300° C. at a rate of 5° C. / min to measure the thermal softening point in accordance with JIS K 7196. A TMA / SS6100 (manufactured by SII) was used for the measurement.

[0091] The higher the thermal softening point, the better the heat resistance of the polyurethane resin.

[0092] [Table 5]

Claims

1. A polyurethane elastic fiber comprising a polyurethane having a polyether structure in its skeleton and a nitrogen-containing aromatic compound, The polyether structure is represented by the following general formula (1): A polyurethane elastic fiber, comprising a nitrogen-containing aromatic compound in an amount of 0.05% by mass or more and 2.0% by mass or less. 【Chemistry 1】 (R １ is an alkylene group having 2 to 6 carbon atoms, R ２ is an alkyl group having 1 to 2 carbon atoms, l, m, and n satisfy 4≦n / (l+m+n)×100≦50.

2. 2. The polyurethane elastic fiber according to claim 1, wherein l, m and n in the general formula (1) satisfy 6≦n / (l+m+n)×100≦16.

3. 3. The polyurethane elastic fiber according to claim 1, wherein the polyurethane elastic fiber contains from 0.2% by mass to 0.8% by mass of a nitrogen-containing aromatic compound.

4. In the general formula (1), -(CH ２ CH ２ CH ２ CHR ２ 3. The polyurethane elastic fiber according to claim 1, wherein n' is the number of -O)n- groups at the terminals of the polyurethane, and 5≦n' / (l+m+n)×100≦30 is satisfied.

5. 3. The polyurethane elastic fiber according to claim 1, wherein the number average molecular weight of the portion of the general formula (1) is 3,000 or more and 30,000 or less.

6. 3. The polyurethane elastic fiber according to claim 1, wherein the bio-based content is 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement according to ISO 16620-2.

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