JP2024077017A - Polyurethane resin composition - Google Patents

Abstract

To provide a polyurethane resin composition that may form highly durable polyurethane elastic fiber having high stress during shrinkage, that is, recovery stress, as well as excellent antioxidative properties.SOLUTION: The polyurethane resin composition 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 resin composition 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

The present invention relates to a polyurethane resin composition, and in particular to a polyurethane resin composition that can provide polyurethane elastic fibers that have high stress during shrinkage, i.e., high recovery stress, and excellent oxidation resistance and are highly durable.

Polyurethane resins have excellent elastic properties and are therefore widely used in paints, coatings, sealants, adhesives, pressure sensitive adhesives, textile processing agents, artificial and synthetic leathers, elastomer raw materials such as rolls, and textile products. In each application, there is a demand to improve the heat resistance of polyurethane resins while maintaining their elastic properties (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.

Due to its excellent elasticity, polyurethane elastic fibers are widely used in elastic clothing applications such as leg wear, innerwear, and sportswear, as well as industrial material applications.

Polyurethane elastic fibers are also required to have high elastic recovery, high strength and elongation, high heat resistance, and heat setting properties. In particular, we have been constantly striving to improve elastic recovery performance by improving the recovery stress.

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. Therefore, for fibers with a large surface area, a composition with high oxidizing power has been required.

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

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

Furthermore, in recent years, with the growing interest in various environmental issues, efforts towards 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).

Japanese Patent Application Laid-Open No. 2-19511 Japanese Patent Application Laid-Open No. 9-136937 JP 2008-69506 A WO2009/011189 JP 2014-522446 A JP 2021-152139 A

However, these conventional techniques were insufficient in terms of recovery stress or oxidation resistance. Thus, there is a demand for a polyurethane resin composition that can provide polyurethane elastic fibers with high recovery stress and excellent oxidation resistance.

The object of the present invention is to provide a polyurethane resin composition that can provide polyurethane elastic fibers that have high stress during shrinkage, i.e., high recovery stress, and excellent oxidation resistance and are highly durable.

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, they have found that a polyurethane resin composition having a higher recovery stress of polyurethane elastic fiber can be obtained with a 2-alkyl group compared to a 3-alkyl group. The inventors have also found that the heat resistance behavior is completely different in the case of a 2-alkyl group compared to a 3-alkyl group. That is, they have found that in the case of a 2-alkyl group, a nitrogen-containing aromatic compound maximizes heat resistance at a specific addition amount. 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 a 2-alkyl group than in the case of a 3-alkyl group, and also, 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, they have found that it is possible to obtain a polyurethane resin composition capable of providing polyurethane elastic fiber having high recovery stress and excellent oxidation resistance and high durability. This allows the material to have both high heat resistance and high durability even when it is made to have a low melting point and high heat setting, 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.

（Ｒ^１は炭素数２～６のアルキレン基、Ｒ^２は炭素数１～２のアルキル基であり、
ｌ，ｍ，ｎは、４≦ｎ／（ｌ＋ｍ＋ｎ）×１００≦５０を満たす）
（２）前記一般式（１）中のｌ，ｍ，ｎが、６≦ｎ／（ｌ＋ｍ＋ｎ）×１００≦１６を満たす（１）に記載のポリウレタン樹脂組成物。
（３）ポリウレタン樹脂組成物中に窒素含有芳香族化合物が０．２質量％以上０．８質量％以下含有される（１）または（２）に記載のポリウレタン樹脂組成物。
（４）前記一般式（１）中の－（ＣＨ_２ＣＨ_２ＣＨ_２ＣＨＲ^２－Ｏ）ｎ－のうち末端にあるものの数をｎ'としたとき、５≦ｎ'／（ｌ＋ｍ＋ｎ）×１００≦３０を満たす（１）～（３）のいずれかに記載のポリウレタン樹脂組成物。
（５）前記一般式（１）部分の数平均分子量が３０００以上３００００以下である（１）～（４）のいずれかに記載のポリウレタン樹脂組成物。
（６）ＩＳＯ １６６２０－２に定められる炭素同位体比測定によるバイオ化率が炭素質量比で３％以上である、（１）～（５）のいずれかに記載のポリウレタン樹脂組成物。 That is, the present invention has the following configuration.
(1) A polyurethane resin composition comprising a polyurethane having a polyether structure in its skeleton and a nitrogen-containing aromatic compound,
The polyether structure satisfies the following general formula (1):
A polyurethane resin composition comprising a nitrogen-containing aromatic compound in an amount of 0.05% by mass or more and 2.0% by mass or less.

(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 the following: 4≦n/(l+m+n)×100≦50
(2) The polyurethane resin composition according to (1), wherein l, m and n in the general formula (1) satisfy 6≦n/(l+m+n)×100≦16.
(3) The polyurethane resin composition according to (1) or (2), wherein the polyurethane resin composition contains a nitrogen-containing aromatic compound in an amount of 0.2% by mass or more and 0.8% by mass or less.
(4) The polyurethane resin composition according to any one of (1) to (3), wherein, when the number of terminal groups among -(CH ₂ CH ₂ CH ₂ CHR ² -O)n- in the general formula (1) is n', the relationship 5≦n'/(l+m+n)×100≦30 is satisfied.
(5) The polyurethane resin composition according to any one of (1) to (4), 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) The polyurethane resin composition according to any one of (1) to (5), wherein the biocontent rate is 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement according to ISO 16620-2.

The present invention makes it possible to provide a polyurethane resin composition that can give polyurethane elastic fibers that have high stress during shrinkage, i.e., high recovery stress, and excellent oxidation resistance and are highly durable.

The present invention will be described in detail below with reference to the embodiments.
First, the polyurethane used in the polyurethane resin composition 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 in an amount of more than 50 mass %.

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 phrase "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. It may also 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 three or more to the extent that it 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 that has been recycled through remolding and re-spun.

In the present invention, the polymer diol having a polyether structure has a polyether structure that satisfies the following general formula (1).

（Ｒ^１は炭素数２～６のアルキレン基、Ｒ^２は炭素数１～２のアルキル基であり、
ｌ，ｍ，ｎは、４≦ｎ／（ｌ＋ｍ＋ｎ）×１００≦５０を満たす）

(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 the following: 4≦n/(l+m+n)×100≦50

When l, m, and n in the general formula (1) satisfy 6≦n/(l+m+n)×100≦16, the balance between the stress during elongation and the stress during elongation recovery is good, and it is preferable because the equivalent properties can be obtained with fewer modified tetramethylene ether units compared to the conventional technology corresponding to the modified tetramethylene ether unit (CH ₂ CH ₂ CH ₂ CHR ² -O), such as (CH ₂ CH ₂ CHRCH ₂ -O). Note that in the 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 a repeating unit, but may be a random body in which each unit is randomly linked.

When the number of -(CH ₂ CH ₂ CH ₂ CHR ² -O)n- groups at the terminals of 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.

In addition, R ¹ may preferably have a carbon number of 2, 3, 5, or 6 other than 4. In the case of R 1 having a carbon number of 2, water vapor permeability is increased and moisture absorption or water absorption functions are imparted. In the case of R 1 having a carbon number of 6, hydrophobicity is imparted conversely. In the cases of R 1 having an odd carbon number of 3 or 5, crystallization during elongation (strain-induced crystallization) of the soft segment is inhibited, contributing to elongation recovery properties.

Furthermore, it is preferable that THF and 2-MeTHF, which are the raw materials for the (CH ₂ CH ₂ CH ₂ CH ₂ -O) and (CH ₂ CH ₂ CH ₂ CHR ² -O) structural units, are made from carbon-neutral biomass-derived components suitable for thermal recycling. In such a case, the degree to which the raw materials are made from components derived from biomass resources 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 method for measuring and identifying the concentration of radioactive carbon (carbon-14) in ISO 16620-2 may be simply referred to as carbon isotope ratio measurement. It is preferable that the polyurethane resin composition of the present invention has a bio-based ratio of 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement.

The other polymer diols preferably contain polyether-based, polyester-based diols, polycarbonate diols, etc. In particular, polyether-based diols are preferably used 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. In addition, two or more of these polymer diols may be mixed and used.

From the viewpoint of obtaining elongation, strength, heat resistance, etc., when made into an elastic fiber, the molecular weight of the polymer diol is preferably a number average molecular weight of 1,000 or more, and more preferably 3,000 or more. By using a polyol with a molecular weight in this range, it is possible to obtain an elastic fiber with excellent elongation, strength, and heat resistance. In addition, it is preferable that the number average molecular weight is 30,000 or less, and more preferably 6,000 or less. By using a polyol with a molecular weight in this range, it is possible to obtain an elastic fiber with excellent elongation, elastic recovery force, heat resistance, and durability due to the synergistic effect with the nitrogen-containing aromatic compound.

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, molded articles obtained from polyurethane resin compositions may be referred to as polyurethane resin molded articles.

The chain extender used to synthesize the polyurethane is preferably at least one of low molecular weight diamines and low molecular weight diols. It is also acceptable to use one that has both a hydroxyl group and an amino group in one molecule, such as ethanolamine.

Preferred low molecular weight diamines include, for example, 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 preferable. By using ethylenediamine, it is possible to easily obtain elastic fibers that are excellent in elongation, elastic recovery, and heat resistance. 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.

Representative 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 polyurethane resin molded bodies and elastic fibers with higher strength can be obtained.

In addition, 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 polyurethane resin molded bodies and polyurethane elastic fibers with high durability and strength. The molecular weight is measured by GPC (gel permeation chromatography) and converted into polystyrene.

It is also preferable to use one or more types of terminal blocking agents in combination for polyurethane. 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.

The polyurethane resin composition of the present invention contains 0.05% by mass or more and 2.0% by mass or less of a nitrogen-containing aromatic compound. This synergistically exhibits the durability of the polyurethane having the polyether structure of the general formula (1) in its skeleton, particularly high durability with excellent oxidation resistance.

（Ｒ^１は炭素数２～６のアルキレン基、Ｒ^２は炭素数１～２のアルキル基であり、
ｌ，ｍ，ｎは、４≦ｎ／（ｌ＋ｍ＋ｎ）×１００≦５０を満たす）

(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 the following: 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 polyurethane elastic fiber may be insufficient, and if it exceeds 2.0% by mass, the heat resistance of the polyurethane resin molded body and polyurethane elastic fiber may decrease significantly, and the yellowing resistance may decrease.

The content of the nitrogen-containing aromatic compound of 0.05% by weight or more and 2.0% by weight or less generally corresponds to the presence of the nitrogen-containing aromatic compound in the range of 0.25 to 13.3 milliequivalents (meq/kg) per 1 kg of the resin composition. On the other hand, aromatic rings containing nitrogen atoms are prone to thermal decomposition, so when the content of the nitrogen-containing aromatic compound is too high (i.e., when the aromatic ring nitrogen atom is in an amount exceeding 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 its 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 in which 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% by mass, the effect of high heat resistance, which is the object of the present invention, cannot be obtained. From these perspectives, 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 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.2% by mass or more and 0.8% by mass or less.

Furthermore, when the number of terminal -(CH ₂ CH ₂ CH ₂ CHR ² -O)n- in the polyurethane having the polyether structure of the general formula (1) in its skeleton is n', it is preferable that the content satisfies 5≦n'/(l+m+n)×100≦30. In such a case, the antioxidant effect with the nitrogen-containing aromatic compound can be exerted synergistically. Furthermore, it is more preferable that the content satisfies 10≦n'/(l+m+n)×100≦15, and a smaller amount of the nitrogen-containing aromatic compound is effective. In such cases, it is also preferable that the content of the nitrogen-containing aromatic compound is 0.1% by mass or more and 0.6% by mass or less.

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, such as benzothiazole and benzoxazole, may also be arranged. Specific examples of such nitrogen-containing aromatic compounds are preferably benzotriazole compounds and triazine compounds known as ultraviolet absorbents, and more specific examples include compounds such as 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]. Listed by trade name are "TINUVIN"-P, "TINUVIN"-213, "TINUVIN"-234, "TINUVIN"-327, "TINUVIN"-328, "TINUVIN"-571, and "TINUVIN"-1577 manufactured by Ciba-Geigy Co., Ltd., "Sumisorb" 250 manufactured by Sumitomo Chemical Co., Ltd., "Cyasorb" UV-541 1, UV-1164, and UV-3638 manufactured by American Cyanamid Co., Ltd., and "ADK STAB" LA-31 manufactured by Asahi Denka Kogyo Co., Ltd., and the like.

In order to produce polyurethane elastic fibers that exhibit 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 nitrogen-containing aromatic compounds 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 volatilization during spinning. From the viewpoint of improving heat resistance and spinnability during dyeing, it is more preferable to use compounds with two or more nitrogen atoms in the aromatic ring, which is presumably because it is easy to form a complex with heavy metals and exerts a chelating effect. Furthermore, in order to fully exert this effect, it is preferable that the chemical structural skeleton of the nitrogen-containing aromatic compound is triazine. It is preferable to carry out tests in advance according to the molecular weight of the nitrogen-containing aromatic compound actually used, the effective number of nitrogen in the aromatic ring, the purpose, etc., and to appropriately determine the optimal value.

And to produce polyurethane elastic fibers with particularly high heat resistance during dyeing, 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-1,3,5-triazine is a suitable nitrogen-containing aromatic compound.

Furthermore, the compounds used as the nitrogen-containing aromatic compounds are preferably liquid compounds with 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 the desired properties to the polyurethane elastic fiber produced, and enabling the polyurethane elastic fiber to have an appropriate degree of transparency, and further, preventing the content of these compounds from decreasing even when exposed to heat 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 end-capping agents are used in combination. Preferred end-capping 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 addition, in the present invention, the polyurethane resin composition may contain various stabilizers other than those mentioned above, such as antioxidants such as hindered phenols, sulfurs, and phosphorus, light stabilizers such as hindered amines, triazoles, benzophenones, benzoates, nickel, and salicylic acid, antistatic agents, lubricants, molecular regulators such as peroxides, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, fluorescent brighteners, fillers, flame retardants, flame retardant assistants, pigments, etc., to the extent that the effects of the present invention are not impaired. 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 powders, metal soaps such as magnesium stearate, bactericides, deodorants, and antibacterial agents containing silver, zinc, or compounds thereof, 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 Nippon Finechem Co., Ltd.

In order to facilitate 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 solution. In order to improve heat resistance and functionality, inorganic substances and inorganic porous substances (e.g., bamboo charcoal, 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 the 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.

In the polyurethane resin composition of the present invention, when an antioxidant is contained, it is preferable that the antioxidant is contained in an amount of 0.002 mass% or more and 5.0 mass% or less. When the content of the antioxidant is within this range, the polyurethane resin composition has practically preferable properties. Particularly preferable antioxidants are hindered phenol compounds, and examples of phenol compounds generally known as antioxidants include those. 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'-oxamidebis[ethyl-3-(3,5-di-t-butyl-4-hydroxide] 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-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 high molecular weight hindered phenol compounds known as antioxidants for polyurethane resin compositions are also preferably used.

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 o-, m-, or p-.

Among these, from the viewpoints of stabilizing the viscosity of the raw material spinning solution for polyurethane elastic fiber, suppressing volatile loss during spinning, and obtaining good spinnability, compounds with a molecular weight of 300 or more are preferred; furthermore, in order to efficiently exhibit 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 these, 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. Also, 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 these, 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.

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 resin composition 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.

Furthermore, as the phenol compound in the present invention, a singly hindered phenol compound is also preferred. As a singly hindered phenol compound, for example, ethylene-1,2-bis(3,3-bis[3-t-butyl-4-hydroxyphenyl]butyrate) (chemical formula below), which has a structure in which a singly hindered hydroxyphenyl group is covalently bonded to a bis-ester skeleton, is preferred.

By including the aforementioned single-hindered phenol compound, the effect of suppressing the deterioration of properties can be enhanced. 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 washed and bleached frequently. In order to obtain a sufficient effect and not adversely affect the physical properties of the fiber, the single-hindered phenol compound is preferably included in the polyurethane resin composition in an amount of 0.15 to 4 mass%, more preferably 0.5 to 3.5 mass%, so that the breaking strength and elongation, composite durability, yellowing resistance, and in some cases light resistance 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%.

The content of the antioxidant in the polyurethane resin composition is preferably in the range of 0.1% by mass to 5.0% by mass. When the content of the antioxidant in the polyurethane resin composition is within this range, it becomes possible to easily control the content of the antioxidant contained inside the polyurethane elastic fiber that is finally produced to the desired content of the antioxidant described above. The content of the antioxidant in the polyurethane resin composition 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.

More specifically, the antioxidant contained is 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 that is known as an antioxidant for polyurethane resin compositions. 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 o-, m-, or p-.

Among these, from the viewpoint of stabilizing the viscosity of the raw material spinning solution for 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 a certain amount of the high molecular weight hindered phenol compound, but from the viewpoint of obtaining better basic physical properties as polyurethane elastic fiber, it is preferable that the amount is not too much.

In the polyurethane resin composition of the present invention, it is preferable that the content of the decomposition products of the antioxidant as described above is also restricted to 1.0 mass% or less. When the content of the decomposition products of the antioxidant is within this range, the practically preferable properties of the polyurethane resin composition, in particular the preferable breaking strength and elongation, discoloration resistance, and durability of the polyurethane elastic fiber using the polyurethane resin composition, are ensured. The content of the decomposition products of the antioxidant is preferably in the range of 1.0 mass% or less, and more preferably in the range of 0.5 mass% or less.

In the polyurethane resin composition of the present invention, when a tertiary amine compound is contained, it is preferable that the content is 0.2 mass% or more and 5.0 mass% or less. When the content of the tertiary amine compound is within this range, the practically preferable properties, spinnability, dyeability, durability, and yellowing resistance of the polyurethane elastic fiber using the polyurethane resin composition are improved.

The tertiary amine compound used in the present invention is not particularly limited as long as it has an amino group in its structure, but from the viewpoint of the chlorine deterioration resistance and yellowing of the polyurethane resin composition, it is particularly preferable to use a compound having only a tertiary amino group in the molecule among the primary to tertiary amino groups.

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 when knitting polyurethane elastic fibers using the polyurethane resin composition, 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. More preferably, it is in the range of 2,000 to 4,000.

By including the above-mentioned tertiary amine compound, the performance of the polyurethane resin composition, particularly the yellowing prevention performance, can be improved. From the viewpoint of ensuring this effect sufficiently and not adversely affecting the physical properties of the polyurethane elastic fiber using the polyurethane resin composition, the tertiary amine compound is preferably included in an amount of 0.2 mass% or more and 5.0 mass% or less, and more preferably 0.5 mass% or more and 4.0 mass% or less, based on the fiber mass. A more preferable content of the tertiary amine compound is in the range of 0.5 mass% or more and 3.0 mass% or less, and even more preferably 0.5 mass% or more and 2.0 mass% or less.

Specific examples of the tertiary amine compounds contained include linear polymeric compounds with a number average molecular weight of 2000 or more, which are produced by the reaction of t-butyldiethanolamine with methylene-bis-(4-cyclohexylisocyanate), polyethyleneimine, and high molecular weight compounds that have a branched structure containing primary amino groups, secondary amino groups, and tertiary amino groups in the molecular skeleton.

In the polyurethane resin composition of the present invention, it is preferable that the content of the decomposition products of the tertiary amine compounds as described above is also restricted to 1.0 mass% or less. When the content of the decomposition products of the tertiary amine compounds is within this range, the polyurethane elastic fiber using the polyurethane resin composition has practically preferable properties, particularly preferable wound yarn shape, composite durability, and yellowing resistance. The content of the decomposition products of the tertiary amine compounds is more preferably in the range of 1.0 mass% or less, and even more preferably in the range of 0.5 mass% or less.

In addition, when the polyurethane resin composition of the present invention contains a crosslinking structure regulator, 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, the polyurethane elastic fiber using the polyurethane resin composition has practically preferable properties, particularly preferable breaking strength and elongation, permanent set rate, and yellowing resistance. 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.

Examples of the crosslinking structure regulator contained in the composition include monoamines and/or diamines. More specifically, examples of monoamines include dimethylamine, diethylamine, cyclohexylamine, etc., and examples of diamines 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 use of a mixture of monoamines and diamines.

The index of the polyurethane obtained in the present invention is determined by evaluating the number average molecular weight ( _Mn ) by GPC. The molecular weight evaluated by GPC is converted into polystyrene. It is preferable to blend polyurethane having a number average molecular weight (Mn) of 20,000 to 120,000 and no peak or shoulder in the detection intensity curve in the region of the number average molecular weight of 30,000 or less. In consideration of the breaking strength and elongation of the polyurethane elastic fiber, the number average molecular weight is preferably in the range of 30,000 to 100,000. More preferably, it is in the range of 40,000 to 80,000. The detection intensity curve is a differential molecular weight distribution curve (the horizontal axis is molecular weight, and the 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.

In the present invention, the molecular weight of the polyurethane resin is preferably in the range of 10,000 to 50,000 in terms of number average molecular weight when a tertiary amine compound with a number average molecular weight in the range of 2,000 to 10,000 or a preferred antioxidant with a molecular weight of 1,000 or more is blended. The molecular weight is measured by GPC and converted into polystyrene.

Next, we will explain in detail the method for producing polyurethane elastic fibers using the polyurethane resin composition of the present invention.

In the present invention, it is preferable to first prepare a polyurethane solution. The method for producing the polyurethane solution and the polyurethane, which is the solute in the solution, may be either the melt polymerization method, the solution polymerization method, or another method. However, the solution polymerization method is more preferable. In the case of the solution polymerization method, there is little generation of foreign matter such as gel in the polyurethane, so it is easy to spin and it is easy to produce polyurethane elastic fibers with low fineness. In addition, the solution polymerization has the advantage that the operation of making a solution is omitted.

The polyurethane elastic fiber using the polyurethane resin composition of the present invention can be used for various applications. Specific examples include tightening strings for pantyhose, brassieres, slips, camisoles, body suits, shorts, girdles, socks and pants, swimsuits, training wear, yoga wear, mountain climbing clothes, work clothes, fireworks clothes, men's and women's suits and other clothing used in combination with natural short fibers, wet suits, 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 clothes, tightening members for waterproof materials, bandages, tightening members for gloves, etc. In other words, it can be used suitably in areas where elastic stretching force is required.

(Examples 1 to 18, Comparative Examples 1 to 10)
The production and evaluation of polyurethane elastic fibers using a polyurethane resin composition 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), and the reaction liquid was neutralized with an aqueous sodium hydroxide solution. This 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) was used as the polyalkylene ether diol.

1.97 moles of 4,4'-MDI per mole of this copolymerized tetramethylene ether diol were charged into a vessel and reacted at 90°C. The resulting reaction product was thoroughly stirred and dissolved in N,N-dimethylacetamide (DMAc) to obtain a solution. A DMAc solution containing 60 mole % ethylenediamine (EDA) and 40 mole % 1,2-propanediamine (1,2-PDA) as chain extenders was then added to the solution containing the reactants, and a DMAc solution containing diethylamine as an end-blocking agent was then added to prepare a polyurethane urea solution with a polymer solid content of 25% by weight. 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.

This polyurethane urea solution was extruded from the spinneret into high-temperature (350°C) inert gas (nitrogen gas) in four filaments, dried by passing through this high-temperature gas, and 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.

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).

The above solution PUUX1, additive solution (B), and nitrogen-containing aromatic compound (C) were mixed uniformly at 99 mass%, 1.0 mass%, and 0.2 mass%, respectively, to form a spinning solution (D).

Using the spinning solution thus obtained, dry spinning is performed at a dry nitrogen temperature of 300°C or higher so that the DMAc in the spinning solution and the floating ethylenediamine are 1/100 or less of the spinning solution content. At this time, the speed ratio of the godet roller and the winder is set to 1:1.20, and a multifilament polyurethane elastic fiber of 22 dtex/3fil is spun, and a treatment agent (oil agent) described later is roller-lubricated by an oiling roller before winding, and the winding speed is 600 m/min, and the fiber is wound on a cylindrical paper tube of 58 mm in length through a traverse guide that gives a winding width of 38 mm using a surface drive winder, to obtain a dry spun polyurethane elastic fiber as a wound body 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 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 a mixture of 80 parts by mass of polydimethylsiloxane having a viscosity of 1× ^{10-5 m2} /s at 25°C, 15 parts by mass of mineral oil having a viscosity of 1.2× ^{10-5 m2} /s at 25°C, and 5 parts by mass of magnesium distearate with an average particle size of 0.5 μm.

[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 (polymer name: PUU1). The glass transition point (Tg) was -70°C. The polyurethane urea constituting this polyurethane urea fiber had a urea group concentration of 0.49 mol/kg and an effective terminal amine concentration of 20 meq/kg.

[Examples 2 to 5]
As shown in Table 1, only the concentration of 2-methyl-tetrahydrofuran in the copolyether polyol was changed (polymer names: PUU2 to PUU5), and polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1.

[Comparative Examples 2 to 5]
As shown in Table 1, only the concentration of 3-alkyltetrahydrofuran in the copolyether polyol was changed (polymer names: PUUX2 to PUUX5), and polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1.

[Examples 6 to 10]
As shown in Table 2, based on Example 2, 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 1.

[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.

[Examples 11 to 13]
As shown in Table 3, based on Example 7, only the secondary hydroxyl group concentration in the copolyether polyol was changed (polymer names: PUU11 to PUU13), and polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1.

[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.

[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.

As can be seen from Table 1, the mechanical properties such as stress at 200% elongation recovery have 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 with the 3-methyl-tetrahydrofuran system, but rather attenuates. The concentration of 2-tetrahydrofuran in the copolyether polyol was 8, and the concentration of 3-tetrahydrofuran in the copolyether polyol was 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.

In Example 17, 2-MeTHF, which is the raw material for the (CH ₂ CH ₂ CH ₂ CHR ² -O) structural unit, was synthesized from hemicellulose origin via D-xylol and furfural in order to use a carbon-neutral biomass resource-derived component suitable for thermal recycling. Furthermore, in Example 18, THF, which was also synthesized from hemicellulose origin via D-xylol and furfural, was used as the raw material for the (CH ₂ CH ₂ CH ₂ CH ₂ -O) structural unit. As a result, performance was shown to be equal to or better than that of Example 7, which used a petrochemical-origin raw material.

In Tables 1 to 4, the content is based on 100 parts by mass of polymer solids in the spinning solution.

Next, the dry-spun polyurethane elastic fiber obtained above (hereinafter, sample yarn) was subjected to the following evaluation.

<Breaking elongation, breaking strength, 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.

A sample having a length of 5 cm (L1) was repeatedly stretched by 300% at a tensile speed of 50 cm/min five times.
The stress at 200% elongation is (G+200).
The stress at 300% elongation was defined as (G1).

Then, the length of the sample was held at 300% extension for 30 seconds. The stress after holding for 30 seconds was taken 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 300% stretch, hold and recovery cycle was repeated until the sample broke at the sixth stretch. The stress at break was (G3), and the sample length at break was (L3). The above properties are calculated using the following formulas.
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 and less than 1.4: ⊚, 1.4 or more and less than 1.5: ◯, 1.5 or more and less than 1.6: △, over 1.6: ×
Stress at 200% elongation recovery = (G-200),
1.2 or more: ⊚, 1.0 or more and less than 1.2: ◯, 0.8 or more and less than 1.0: △, less than 0.8: ×
Permanent set rate (%) = 100 × ((L2) - (L1)) / (L1)
Less than 20: ◎, 20 to less than 22: 〇, 22 to less than 24: △, 24 or more: ×
Stress relaxation rate (%) = 100 × ((G1) - (G2)) / (G1)
Under 25: ◎, 25 to under 28: 〇, 28 to under 31: △, 31 or more: ×.

<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 a well number of 9/inch and a course number of 18/inch was produced by a conventional knitting method to form a raw knitted fabric.

The resulting raw knit fabric was preset at 170°C for 60 seconds under 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 (dry heat treatment at 175°C for 60 seconds, then removed and cooled to room temperature, then dry heat treatment at 180°C for 60 seconds), and then subjected to a bending tester at a maximum elongation of 20% in both the vertical and horizontal directions, 2 times per 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 chemicals 1 and 2 were applied in this way was a model that reproduced the nylon-based stretch raw knit fabric before dyeing, which has trace amounts of machine oil (contaminated with metals) and nylon spinning oil adhering to it during knitting. The amount of chemical 1 attached to 0.9 g of raw knit fabric was 3.0 mg, and the amount of chemical 2 attached was 3.0 mg.

The resulting stretch fabric was dyed in a conventional manner. The degree of damage to the polyurethane tissue in the resulting dyed stretch fabric was observed visually or under magnification, and judged according to the following criteria. The judgement was performed by five people, and the most frequent judgement (the judgement that appeared most frequently) was used. When the judgements were divided into two, two, 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.

<Lightfastness, yellowing resistance, and composite durability>
After the following exposure treatments (a), (b), and (c), the respective characteristics were determined as follows.

Light resistance The sample yarn was subjected to the following exposure treatment (A) while being stretched to 100%, and the retention 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 processing - b value before exposure processing

Measurement of Yellowing Property The sample form and measurement were carried out as follows.
The sample yarn was wound tightly on a 5 x 5 cm sample plate with a minimum load so 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 in close contact. The b value was measured using a Hunter type color difference meter in accordance with JIS L 1013 C method (Hunter's method) 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 were calculated according to JIS Z 8701)

Composite durability The sample yarn was stretched to 100% and subjected to the following exposure treatments (a), (b), and (c), and the retention of breaking strength thereafter was determined.

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 sample was exposed to a temperature of 63° C. and a humidity of 60% 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 8 times.

The criteria for judgment are as follows:
Light resistance: 80% or more is ◎, 60% to less than 80% is 〇, 40% to less than 60% is △, and less than 40% is ×
Yellowing: Less than 3 = ◎, 3 to less than 6 = 〇, 6 to less than 10 = △, 10 or more = ×
- Composite durability: 60% or more = ◎, 40% to less than 60% = 〇, 20% to less than 40% = △, less than 20% = ×

<Molecular weight>
The molecular weight measurement by GPC was carried out under the following conditions.
Column: Showa Denko K.K., SHODEX KF-806M (2 columns) Solvent: N,N-dimethylacetamide 1 ml/min
Temperature: 40°C
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).

The tensile strength at break, elongation at break, residual strain rate, and heat softening point of the polyurethane resin composition measured by the following methods using the same polyurethane urea solution as that spun in Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 5. As is clear from Table 5, the polyurethane resin composition of the present invention exhibits good properties even when molded into a film.

[1] Preparation of film The polyurethane resin solution was applied to a release-treated glass plate to a thickness of 1.0 mm, and then dried in a circulating air dryer at 70° C. for 3 hours. The resulting film was then peeled off from the glass plate to prepare a film with a thickness of approximately 0.2 mm.

[2] Method for measuring strength and elongation of film 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] Measurement method of residual strain rate From the film obtained above, a rectangular test piece of 100 mm length × 5 mm width was cut out and marked so that the distance between the marks was 50 mm. This test piece was set in the chuck of an Instron type tensile tester (Shimadzu Corporation Autograph) and elongated at a constant speed of 500 mm/min in an atmosphere of 25°C until the distance between the marks became 300%, and then immediately returned to the distance between the chucks before elongation at the same speed.
The distance between the marked lines after the above-mentioned operation (D1) was measured, and the residual strain rate (%) was calculated using this value and the distance between the marked lines before the test (D0 = 50 mm) according to the following formula.
Residual distortion rate (%) = {(D1 - D0) / D0} x 100

[4] Method for measuring thermal softening point 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.
The higher the thermal softening point, the better the heat resistance of the polyurethane resin composition.

Claims (6)

A polyurethane resin composition 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 resin composition comprising a nitrogen-containing aromatic compound in an amount of 0.05% by mass or more and 2.0% by mass or less.

(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. The polyurethane resin composition according to claim 1, wherein l, m, and n in the general formula (1) satisfy 6≦n/(l+m+n)×100≦16. The polyurethane resin composition according to claim 1 or 2, wherein the polyurethane resin composition contains 0.2% by mass or more and 0.8% by mass or less of a nitrogen-containing aromatic compound. The polyurethane resin composition according to claim 1 or 2, wherein, when the number of -(CH ₂ CH ₂ CH ₂ CHR ² -O)n- groups at the terminals of the polyurethane in the general formula (1) is n', the relationship 5≦n'/(l+m+n)×100≦30 is satisfied. The polyurethane resin composition according to claim 1 or 2, wherein the number average molecular weight of the general formula (1) portion is 3,000 or more and 30,000 or less. The polyurethane resin composition according to claim 1 or 2, in which the bio-based content is 3% or more by carbon mass ratio as determined by carbon isotope ratio measurement according to ISO 16620-2.