Polyurethane resin composition and polyurethane elastic fiber

Abstract

To provide a polyurethane elastic fiber having high stress during contraction, and excellent breaking strength and elongation.SOLUTION: There is provided a polyurethane resin composition primarily composed of a polyurethane resin using a polymer diol and a diisocyanate as starting materials. The polyurethane resin composition contains the polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the following formula (1) and a polymer diol represented by formula (2) below, together comprising 50 mass% or more of the entire polymer diol. Mass ratios r(1) and r(2) of structural parts respectively corresponding to the following formulas (1) and (2) to the entire structural parts derived from the polymer diols satisfy the following relational formula (A). In formulas (1) and (2), bonds marked with * represent a bond with a hydrogen atom, or a bond between O and C=O in the urethane bond.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 a high stress upon shrinkage, i.e., a high recovery stress, and high durability. [Background technology]

[0002] Due to their excellent elastic properties, polyurethane resins are widely used in a variety of applications, including laminating films, coatings, sealants, adhesives, pressure-sensitive adhesives, textile processing agents, paints, artificial and synthetic leathers, rolls, and other elastomer raw materials, as well as textile products. In each application, there is a demand for improving 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 during the production and processing of final products using polyurethane resins as raw materials and to improve the durability of the final products.

[0003] Polyurethane elastic fibers are widely used in stretchable clothing such as legwear, innerwear, and sportswear, as well as industrial materials, due to their excellent elasticity.

[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] To achieve high elastic recovery performance, it is important to suppress stress-induced crystallization of the soft segment. Previously, methods for imparting disorder to the polymer main chain in the soft segment have been disclosed. For example, it is known that a polyurethane structure consisting of a copolyether diol of tetrahydrofuran (THF) and 3-alkyltetrahydrofuran and a diisocyanate, or a polyurethane structure consisting of a copolyether diol of tetrahydrofuran and 2-alkyltetrahydrofuran and a diisocyanate, can result in a soft segment with a higher stress during contraction, i.e., a higher recovery stress, compared to a polyether diol consisting solely of tetrahydrofuran (also referred to as polytetramethylene ether diol, PTMG, PO4G, etc.) (Patent Documents 1 and 2).

[0006] Furthermore, methods for mixing different types of polymer main chains in the soft segment have also been disclosed. For example, it is known that a polyurethane structure consisting of a polymer diol made by mixing PTMG and polypropylene ether (PPG) and a diisocyanate, and a polyurethane structure consisting of a polymer diol copolymerized with tetrahydrofuran and ethylene oxide and a diisocyanate can result in a soft segment with a higher recovery stress (Patent Documents 3 and 4). Furthermore, in recent years, growing interest in environmental issues has led to calls for efforts to transition to a sustainable society for organic materials in general, and polyurethane elastic fibers, which have a relatively low content in elastic materials, are no exception. Because their content in elastic clothing and industrial materials is relatively low, they are difficult to separate and extract, 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]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2-19511 [Patent Document 2] Japanese Patent Publication No. 2022-79647 [Patent Document 3] Special Publication No. 2001-505596 [Patent Document 4] Patent Publication No. 2001-226823 [Patent Document 5] Special Publication No. 2014-522446 [Patent Document 6] Patent Publication No. 2021-152139 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the polyurethane resin compositions of the prior art have yielded polyurethane elastic fibers that are insufficient in terms of recovery stress and breaking strength / elongation. Thus, there is a demand for polyurethane resin compositions and polyurethane elastic fibers that can provide polyurethane elastic fibers with high recovery stress and high breaking strength / elongation.

[0009] An object of the present invention is to provide a polyurethane resin composition and polyurethane elastic fiber that can give highly durable polyurethane elastic fibers that have a high stress during shrinkage, i.e., a high recovery stress, and high breaking strength and elongation. [Means for solving the problem]

[0010] To address this issue, the inventors investigated the compatibility of linear methylene ethers with 2 to 6 carbon atoms as a method for blending different polymer main chains. Similar studies have been published on polyamide resins (e.g., JP 2009-526892 A and JP 2016-532728 A), but few have been published on polyurethane resins. Specifically, they investigated a mixture of two compounds selected from the group consisting of polydimethylene ether glycol (polyethylene glycol), polytrimethylene ether glycol, polytetramethylene ether glycol, polypentamethylene ether glycol, and polyhexamethylene ether glycol. Among these, the inventors discovered that the combination of polytrimethylene ether glycol and polytetramethylene ether glycol resulted in specific improvements in recovery stress and breaking strength / elongation, leading to the present invention. Furthermore, the inventors discovered that the inclusion of a block or random copolymer containing repeating units of trimethylene ether and tetramethylene ether promoted compatibilization, resulting in more specific improvements in recovery stress and breaking strength / elongation. In other words, they discovered that a mixture of polytrimethylene ether glycol, polytetramethylene ether glycol, and alkylene ether glycol obtained by polycondensation of 1,3-propanediol and tetrahydrofuran resulted in specific improvements in recovery stress and breaking strength and elongation.

[0011] That is, the present invention has the following configuration. [1] A polyurethane resin composition comprising as its main component a polyurethane resin made from polymer diol and diisocyanate as starting materials, wherein the polyurethane resin contains, as the starting polymer diol, a polymer diol whose structure after removing hydrogen from both ends is represented by the following formula (1) and a polymer diol whose structure after removing hydrogen from both ends is represented by the following formula (2) in total, accounting for 50% by mass or more of the entire polymer diol, and wherein the mass ratios r(1) and r(2) of the structural moieties corresponding to the following formulas (1) and (2) to the entire structural moieties derived from the polymer diol satisfy the following relational formula (A).

[0012]

number

[0013] [ka]

[0014] [ka]

[0015] In formulas (1) and (2), the bonds marked with * represent: These structural moieties represent bonds with hydrogen atoms in the polymer diol, When these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when they are present at locations other than the terminals of the polyurethane resin, they represent bonds between O and C=O in the urethane bond. [2] The polyurethane resin composition according to [1], wherein the starting polymer diol further contains a polymer diol whose structure, obtained by removing hydrogen atoms from both ends, is represented by the following formula (3), and the mass ratio r(3) of the structural moiety corresponding to the following formula (3) to the total structural moieties derived from the polymer diol, and the mass ratios r(1) and r(2) satisfy the following relational formula (B):

[0016]

number

[0017] [ka]

[0018] In formula (3), the linkage of the unit structures having the repeating numbers c and d may be in a block or random form, Bonds marked with * are These structural moieties represent bonds with hydrogen atoms in the polymer diol, When these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when they are present at locations other than the terminals of the polyurethane resin, they represent bonds between O and C=O in the urethane bond. [3] The polyurethane resin composition according to [1] or [2], wherein the mass ratios r(1) and r(2) satisfy the following relational formula (A'):

[0019]

number

[0020] [4] The polyurethane resin composition according to [2], wherein the mass ratios r(1), r(2), and r(3) satisfy the following relational formula (B'):

[0021]

number

[0022] [5] The polyurethane resin composition according to any one of [1] to [4], wherein the polymer diol as a whole, having a structure of the portion after removing hydrogen atoms from both ends and represented by any one of formulas (1) to (3), has a number average molecular weight of 1,000 to 30,000, and the ratio of the number average molecular weight of the polymer diol as a portion after removing hydrogen atoms from both ends and represented by formula (2) to the number average molecular weight of the polymer diol as a portion after removing hydrogen atoms from both ends and represented by formula (1) is 1.00 to 1.16. [6] The polyurethane resin composition according to any one of [1] to [5] above, wherein the biocontent determined by carbon isotope ratio measurement according to ISO 16620-2 is 3% or more in terms of carbon mass ratio. [7] A polyurethane elastic fiber made from the resin composition of any one of [1] to [6] above. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a polyurethane resin composition and a polyurethane elastic fiber that can give a highly durable polyurethane elastic fiber having a high stress during shrinkage, i.e., a high recovery stress, and a high breaking strength and elongation. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described in detail below with reference to embodiments.

[0025] First, we will describe the polyurethane used in the polyurethane resin composition and polyurethane elastic fiber of the present invention. The polyurethane described here is preferably used as a main component, and the main component here refers to a component contained in the polyurethane resin composition and polyurethane elastic fiber in an amount of more than 50 mass %.

[0026] The polyurethane used in the present invention has a polyether structure in its skeleton. Polyurethanes having a polyether structure in their skeleton have a structure containing at least a polymer diol having a polyether structure as a starting material. Here, "having a structure contained in the starting material" refers to the structure of the corresponding portion of the starting material to explain the polymer skeleton structure, and the starting material and its synthesis method are not particularly limited. For example, the polyurethane may be a polyurethane urea composed of a polymer diol having a polyether structure, a diisocyanate, and a low-molecular-weight diamine as a chain extender, or a polyurethane urethane composed of a polymer diol having a polyether structure, a diisocyanate, and a low-molecular-weight diol as a chain extender. Furthermore, the polyurethane 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 trifunctional or higher polyfunctional glycols, isocyanates, etc., as long as the effects of the present invention are not impaired.

[0027] In the present invention, the polymer diol having a polyether structure contains a polymer diol in which the structure of the portion obtained by removing hydrogen from both ends is represented by the following formula (1) and a polymer diol in which the structure of the portion obtained by removing hydrogen from both ends is represented by the following formula (2), in a total amount of 50 mass % or more of the entire polymer diol.

[0028] [ka]

[0029] [ka]

[0030] In formulas (1) and (2), a and b are integers, and bonds marked with * are These structural moieties represent bonds with hydrogen atoms in the polymer diol, and when these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when they are present at any location other than the terminals of the polyurethane resin, they represent bonds between O and C=O in the urethane bond.

[0031] The mass ratios r(1) and r(2) of the structural moieties corresponding to formula (1) and formula (2) to the total structural moieties derived from the polymer diol are expressed by the following relational expression (A):

[0032]

number

[0033] It is essential to satisfy the following.

[0034] In this specification, "a polymer diol whose structure after removing hydrogen from both ends is represented by formula (n)" may be abbreviated as "a polymer diol having a structure of formula (n)".

[0035] The researchers also found that when the polyurethane resin contained as the main component of the polyurethane resin composition of the present invention satisfies the above-mentioned relationship (A), the soft segment melting point of a polyurethane elastic fiber formed from the polyurethane resin composition, as measured by differential scanning calorimetry (DSC), is lower than when polyurethane resins formed solely from the polymer diols having the structures of formulas (1) and (2) are used as starting materials, and the endothermic enthalpy is also reduced. This suppresses crystallization of the structural moieties represented by formulas (1) and (2) in the polyurethane elastic fiber when the polyurethane resin composition of the present invention is spun to obtain a polyurethane elastic fiber, which is preferable because it results in a good balance between the stress during elongation and the stress during elongation recovery. Hereinafter, the "polyurethane resin contained as the main component of the polyurethane resin composition of the present invention" may be abbreviated as the "polyurethane resin of the present invention."

[0036] It was also found that when the polyurethane resin of the present invention satisfies the above-mentioned relational formula (A), the hard segment melting point of the polyurethane elastic fiber measured by DSC is higher than when the polymer diols having the structures of formulas (1) and (2) are used alone as starting materials, and the amount of endothermic enthalpy also tends to be larger. This is thought to be because the separation of the soft segment and the hard segment is clearer, making the hard segment crystals stronger, resulting in the effects of increasing the breaking strength and breaking elongation.

[0037] Furthermore, when the polyurethane resin of the present invention satisfies the following relational formula (A'), the balance of stress during elongation and recovery, as well as the breaking strength and breaking elongation of the molded article or polyurethane elastic fiber obtained from this polyurethane resin composition become more preferable.

[0038]

number

[0039] In order to further improve the balance of stress during elongation and recovery, as well as the breaking strength and breaking elongation, it is more preferable that the starting polymer diol further contains a polymer diol whose structure, excluding hydrogen atoms at both ends, is represented by the following formula (3):

[0040] [ka]

[0041] Here, formula (3) is a composition formula showing the content ratio of the unit structures, and c and d represent only the content ratio of each unit structure. That is, the unit structures (CH2CH2CH2-O) and (CH2CH2CH2CH2-O) may be linked in either a block or random form. From the viewpoint of more effective compatibilization, a random form is more preferable. Furthermore, in the structural moieties shown in formula (3), the bonds marked with * represent bonds with hydrogen atoms in the polymer diol, and when these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when these structural moieties are present at locations other than the terminals of the polyurethane resin, they represent bonds between O and C=O in the urethane bond.

[0042] By including a polymer diol having the structure of formula (3) as a starting polymer diol, the moiety of the structure of formula (1) and the moiety of the structure of formula (2) in the polyurethane resin of the present invention are made compatible with each other, and in a polyurethane elastic fiber made of a polyurethane resin composition containing such a polyurethane resin as a main component, the effect resulting from the crystallization of the soft segment and hard segment in the polyurethane elastic fiber confirmed by the above-mentioned DSC becomes more pronounced, which is thought to be why the balance of stress during elongation recovery and the breaking strength and breaking elongation can be further improved.

[0043] The starting polymer diol further contains a polymer diol in which the structure of the portion excluding hydrogen atoms at both ends is represented by formula (3), and the mass ratio r(3) of the structural portion corresponding to formula (3) to the entire structural portion derived from the polymer diol and the mass ratios r(1) and r(2) satisfy the following relational formula (B). In this case, the polyurethane elastic fiber made of a polyurethane resin composition containing such a polyurethane resin as a main component exhibits a more favorable balance of stress during elongation recovery, as well as a more favorable breaking strength and breaking elongation. Furthermore, the spinning solution stability and spinning continuity are more favorable.

[0044]

number

[0045] The above-mentioned effect is more pronounced when the following relational formula (B') is satisfied, which is more preferable.

[0046]

number

[0047] From the viewpoint of obtaining elongation, strength, heat resistance, and the like when made into polyurethane elastic fibers, the number-average molecular weight of the polymer diol as a starting material for the polyurethane resin of the present invention, in which the structure of the portion obtained by removing hydrogen from both ends is represented by Formulas (1) to (3), is preferably 1,000 or more, more preferably 1,800 or more. By using a polymer diol having a number-average molecular weight within this range, a polyurethane resin composition that can provide polyurethane elastic fibers with superior elongation, strength, and heat resistance can be obtained. Furthermore, the number-average molecular weight is preferably 30,000 or less, more preferably 10,000 or less. By using a polymer diol having a number-average molecular weight within this range, a polyurethane resin composition that can provide polyurethane elastic fibers with superior elongation, elastic recovery, and heat resistance can be obtained.

[0048] The number-average molecular weight of the polymer diol having the formula (1) structure is preferably 8%±8% greater than the number-average molecular weight of the polymer diol having the formula (2) structure. That is, when the ratio of the number-average molecular weight of the polymer diol having the formula (2) structure to the number-average molecular weight of the polymer diol having the formula (1) structure is 1.00 to 1.16, the soft segment lengths at maximum elongation are uniform, resulting in a better balance of stress during elongation and recovery, as well as better breaking strength and breaking elongation. For example, when the number-average molecular weight of the polymer diol having the formula (1) structure is 1800, the theoretical molecular chain length at maximum elongation is 12.2 nm, and the theoretical number-average molecular weight of the polymer diol having the formula (2) structure of 12.2 nm is approximately 2000.

[0049] It is also more preferable that the number average molecular weight of the polymer diol having the structure of formula (3) is an intermediate value between the number average molecular weight of the polymer diol having the structure of formula (1) and the number average molecular weight of the polymer diol having the structure of formula (2). This improves the balance of stress during elongation and recovery, as well as the breaking strength and breaking elongation, and also improves the polymerization stability and the stability of the spinning solution.

[0050] Furthermore, the raw materials for the structural units of formula (1) and formula (2) are preferably components derived from carbon-neutral biomass resources that are suitable for thermal recycling. In such cases, the degree to which components derived from biomass resources are used as raw materials is expressed as the bio-based content ratio. The bio-based content ratio can be obtained by ISO 16620-2, a method for measuring and identifying the concentration of radiocarbon (carbon-14). In the present invention, the method for measuring and identifying the concentration of radiocarbon (carbon-14) specified in ISO 16620-2 may be simply referred to as carbon isotope ratio measurement. The polyurethane resin composition and polyurethane elastic fiber of the present invention preferably have a bio-based content ratio of 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement.

[0051] The polymer diol other than the polymer diols having the structures of formulas (1) to (3) preferably contains one having a structure such as a polyether-based diol, a polyester-based diol, or a polycarbonate diol. 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. Two or more of these polymer diols may be mixed and used.

[0052] The molecular weight of the polymer diol other than the polymer diols having the structures of Formulas (1) to (3) is preferably a number-average molecular weight of 1,000 or more, more preferably 3,000 or more, from the viewpoint of obtaining elongation, strength, heat resistance, etc. when made into an elastic fiber. By using a polyol having a number-average molecular weight in this range, polyurethane elastic fibers with excellent elongation, strength, and heat resistance can be obtained. Furthermore, a number-average molecular weight of 30,000 or less is preferably used, more preferably 10,000 or less. By using a polyol having a number-average molecular weight in this range, polyurethane elastic fibers with excellent elongation, elastic recovery, and heat resistance can be obtained.

[0053] Next, as diisocyanates, aromatic diisocyanates such as diphenylmethane diisocyanate (hereinafter sometimes abbreviated as MDI), tolylene diisocyanate, 1,4-diisocyanatobenzene, 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, methylenebis(cyclohexylisocyanate), 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 are particularly useful for suppressing 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.

[0054] The chain extender used in synthesizing the polyurethane is preferably at least one of a low molecular weight diamine and a low molecular weight diol, although it may also be one having both a hydroxyl group and an amino group in one molecule, such as ethanolamine.

[0055] 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 preferred. The use of ethylenediamine facilitates the production of polyurethane elastic fibers with excellent 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.

[0056] 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 preferred. The use of these diol-extended polyurethanes results in higher heat resistance, and allows for the production of polyurethane resin molded articles and elastic fibers with higher strength.

[0057] In the present invention, the molecular weight of the polyurethane resin 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 number average molecular weight is measured by GPC and converted into polystyrene.

[0058] The polyurethane resin preferably contains one or more terminal blocking agents, such as monoamines (e.g., dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, and diamylamine), monools (e.g., ethanol, propanol, butanol, isopropanol, allyl alcohol, and cyclopentanol), and monoisocyanates (e.g., phenylisocyanate).

[0059] The polyurethane resin composition and polyurethane elastic fiber of the present invention preferably contain 0.05% by mass or more and 2.0% by mass or less of a nitrogen-containing aromatic compound. This synergistically exhibits durability, particularly high durability with excellent antioxidant properties, with the polyurethane having the polyether structure of general formulas (1) and (2) in its skeleton. If the nitrogen-containing aromatic compound content is less than 0.05% by mass, the durability of the polyurethane resin molded product and polyurethane elastic fiber may be insufficient. If the content exceeds 2.0% by mass, the heat resistance of the polyurethane resin molded product and polyurethane elastic fiber may be significantly reduced, resulting in reduced yellowing resistance.

[0060] The nitrogen-containing aromatic compound contained in the present invention is specifically a compound having a nitrogen-containing aromatic heterocycle in which a nitrogen atom is arranged in an aromatic ring in the molecule. Examples of the chemical structure skeleton include pyrrole, pyridine, carbazole, and quinoline having one nitrogen-containing aromatic heterocycle, imizazole, pyrazole, pyridazine, pyrazine, pyrimidine, naphthyridine, and phenanthroline having two nitrogen-containing aromatic heterocycles, and triazine, benzotriazole, and naphthyridine having three nitrogen-containing aromatic heterocycles. Benzothiazole, benzoxazole, and other heteroatoms other than nitrogen may also be arranged. Specific examples of such nitrogen-containing aromatic compounds include benzotriazole compounds and triazine compounds known as ultraviolet absorbers, 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 trade names 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 Cynamid Co., Ltd., and "Adekastab" LA-31 manufactured by Asahi Denka Kogyo Co., Ltd.

[0061] In polyurethane elastic fibers, a nitrogen-containing aromatic compound content of 0.05% to 2.0% by mass generally corresponds to a nitrogen-containing aromatic compound present in a range of 0.25 to 13.3 milliequivalents (meq / kg) per 1 kg of polyurethane elastic fiber. However, because nitrogen-containing aromatic rings are prone to thermal decomposition, excessive nitrogen-containing aromatic compound content (i.e., aromatic ring nitrogen atoms exceed 13.3 milliequivalents) can lead to radical generation due to thermal decomposition, rather than the synergistic effect with polyurethanes having polyether structures of general formula (1) in their backbones. This can result in reduced heat resistance or the formation of quinone structures, leading to thermal discoloration, and thus potentially impairing performance such as high heat resistance. While nitrogen-containing aromatic compounds may be used in large amounts as light stabilizers, the nitrogen-containing aromatic compound content is preferably 0.1% to 0.6% by mass.

[0062] In order to obtain 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, nitrogen-containing aromatic compounds are preferred from the viewpoint of suppressing volatile loss during spinning. Furthermore, from the viewpoint of improving heat resistance and spinnability during dyeing, compounds having two or more nitrogen atoms in the aromatic ring are more preferred, presumably because they facilitate complex formation with heavy metals and exhibit a chelating effect. Furthermore, in order to fully exhibit this effect, the chemical structural skeleton of the nitrogen-containing aromatic compound is preferably triazine. It is preferable to conduct tests in advance depending on the molecular weight of the nitrogen-containing aromatic compound actually used, the effective number of nitrogen atoms in the aromatic ring, the intended use, and other factors, and to determine the optimal values ​​as appropriate.

[0063] In order to obtain 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 preferred as the nitrogen-containing aromatic compound.

[0064] 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 the polyurethane resin when the polyurethane resin composition is made, imparting desired properties to the polyurethane elastic fiber produced thereby, and enabling the polyurethane elastic fiber to have an appropriate transparency, and further preventing the content of these compounds from decreasing even when exposed to heat during the spinning process, preventing discoloration and yellowing of the polyurethane elastic fiber.

[0065] In the present invention, the polyurethane elastic fiber or the polyurethane spinning solution may contain various stabilizers other than those described above, such as hindered phenol-based, sulfur-based, or phosphorus-based antioxidants, hindered amine-based, triazole-based, benzophenone-based, benzoate-based, nickel-based, or salicylic acid-based light stabilizers, 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, and pigments, within ranges that do not impair the effects of the present invention. For example, light fasteners and antioxidants such as 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, disinfectants, 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 phosphate-based agents are preferably included, and these may also be reacted with a polymer. Furthermore, to further enhance durability, particularly against 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.

[0066] Furthermore, 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. Furthermore, from the viewpoint of improving heat resistance and functionality, inorganic substances or inorganic porous materials (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 the spinning dope by mixing the polyurethane solution with the above-mentioned modifier, or may be contained in advance in the polyurethane solution or dispersion before mixing. The content of these additives is determined appropriately depending on the purpose, etc.

[0067] When the polyurethane elastic fiber of the present invention contains an antioxidant, it is preferable that the antioxidant content be 0.002% by mass or more and 5.0% by mass or less. When the antioxidant content is within this range, the polyurethane elastic fiber has practically preferable properties. Particularly preferable antioxidants are hindered phenol compounds, such as phenol compounds generally known as antioxidants.For example, 3,5-di-t-butyl-4-hydroxytoluene, 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-hydroxybenzyl-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 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 hindered phenol compounds known as antioxidants for polyurethane elastic fibers are also preferably used.

[0068] Preferred examples of such 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 either p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be any of o-, m-, and p-.

[0069] Among these, compounds with a molecular weight of 300 or more are preferred from the viewpoints of stabilizing the viscosity of the raw material spinning solution for polyurethane elastic fibers, suppressing volatilization loss during spinning, and achieving good spinnability. 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. Furthermore, when triazine compounds are selected for 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.

[0070] Furthermore, from the viewpoint of suppressing deterioration of various durability properties, such as heat resistance, composite durability, light resistance, and yellowing, due to oxidation, 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.

[0071] The inclusion of the monohindered phenol compound described above enhances the effect of suppressing property degradation. This type of hindered phenol compound is effective, particularly in the case of underwear and other items that are frequently washed and bleached, because it specifically works to suppress the molecular weight of the polyurethane resin that constitutes the polyurethane elastic fiber. To ensure this effect is sufficient and not adversely affect the physical properties of the fiber, the monohindered phenol compound is preferably contained in an amount of 0.15 to 4 mass% of the polyurethane elastic fiber, more preferably 0.5 to 3.5 mass%, to ensure breaking strength and elongation, composite durability, yellowing resistance, and, in some cases, lightfastness. The antioxidant content is more preferably in the range of 0.2 to 3.0 mass%, and even more preferably 0.5 to 2.0 mass%.

[0072] 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, it becomes possible to easily control the content of the antioxidant contained inside the polyurethane elastic fiber that is finally produced to the desired antioxidant content 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.

[0073] The antioxidant contained is preferably a hindered phenol compound having a molecular weight of 1,000 or more, and is preferably a hindered phenol compound having a molecular weight of 1,000 or more, which is known as an antioxidant for polyurethane elastic fibers. There are no particular limitations on the molecular weight other than the relatively high molecular weight of 1,000 or more. 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 with compounds such as cresol, ethylphenol, and t-butylphenol. Here, divinylbenzene and chloromethylstyrene may be either p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be o-, m-, or p-.

[0074] 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 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 preferable to contain a certain amount of this high-molecular-weight hindered phenol compound, 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.

[0075] In the polyurethane elastic fiber of the present invention, the content of the decomposition products of the antioxidant as described above is also preferably limited to 1.0% by mass or less. If the content of the decomposition products of the antioxidant is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable breaking strength and elongation, color fastness, and durability, are ensured. 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.

[0076] The polyurethane resin composition of the present invention preferably contains a tertiary amine compound. By including a tertiary amine compound in the polyurethane resin composition, the performance, particularly the anti-yellowing performance, of the polyurethane elastic fiber obtained by spinning the polyurethane resin composition can be improved. To ensure this effect is sufficient and to avoid adversely affecting 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, and more preferably 0.5% by mass or more and 4.0% by mass or less, relative to the mass of the polyurethane resin composition. The content of the tertiary amine compound is more preferably in the range of 0.5% by mass or more and 3.0% by mass or less, and even more preferably in the range of 0.5% by mass or more and 2.0% by mass or less.

[0077] When the polyurethane elastic fiber of the present invention contains a tertiary amine compound, the content is preferably 0.2% by mass or more and 5.0% by mass or less, and the more preferred range is the same as that of the polyurethane resin composition. 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.

[0078] When the polyurethane elastic fiber of the present invention contains a tertiary amine compound, the tertiary amine compound to be used is not particularly limited as long as it is a compound having an amino group in its structure. However, from the viewpoint of the chlorine degradation resistance and yellowing of the polyurethane elastic fiber, it is particularly preferred that the compound have only a tertiary amino group in the molecule, out of the primary to tertiary amino groups.

[0079] 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 and 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.

[0080] When the polyurethane elastic fiber of the present invention contains a tertiary amine compound, if the tertiary amine compound has a number-average molecular weight of less than 2,000, it may fall off due to friction with guides or knitting needles during knitting of the polyurethane elastic fiber, or may flow out during processing in a dyeing bath, thereby deteriorating the water-repellent finish. Therefore, the number-average molecular weight must be 2,000 or more. In consideration of solubility in the 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.

[0081] In the polyurethane resin composition and polyurethane elastic fiber of the present invention, the content of the decomposition products of the tertiary amine compounds as described above is also preferably limited to 1.0% by mass or less. When the content of the decomposition products of the tertiary amine compounds is within this range, practically preferable polyurethane elastic fiber properties, particularly preferable wound yarn shape, composite durability, and yellowing resistance, are obtained. 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.

[0082] Furthermore, the polyurethane resin composition and polyurethane elastic fiber of the present invention preferably contain a crosslinking structure modifier, and in this case, the content is preferably 0.002% by mass or more and 2.0% by mass or less. The crosslinking structure modifier is an agent that is added after the polymerization of the polyurethane resin is completed by adding a polymerization terminator. When the content of the crosslinking structure modifier is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable breaking strength and elongation, permanent set rate, and yellowing resistance, are ensured. The content of the crosslinking structure modifier 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.

[0083] The crosslinking structure regulator contained therein may be a monoamine and / or a diamine. More specifically, monoamines include dimethylamine, diethylamine, cyclohexylamine, etc., and diamines include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 1,3-cyclohexyldiamine, hexahydromethanephenylenediamine, and 2-methylpentamethylenediamine. Particularly preferred is the use of a mixture of monoamines and diamines.

[0084] In the present invention, the molecular weight of the polyurethane resin contained in the polyurethane resin composition after being made into polyurethane elastic fiber is preferably in the range of 10,000 to 50,000 in number average molecular weight when a tertiary amine compound with a number average molecular weight 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. The molecular weight of the polyurethane resin contained in the polyurethane resin composition after being made into polyurethane elastic fiber may be abbreviated as the molecular weight as polyurethane elastic fiber.

[0085] The polyurethane resin or polyurethane elastic fiber obtained by the present invention may be recycled and incorporated as part of the polyurethane raw materials, provided that the scope of the present invention is not exceeded.

[0086] 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 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 melt polymerization, solution polymerization, or another method. However, solution polymerization is more preferable. In the case of solution polymerization, there is little generation of foreign matter such as gel in the polyurethane, making it easy to spin and to produce low-fineness polyurethane elastic fibers. In addition, solution polymerization has the advantage of eliminating the step of preparing a solution. As the polyurethane elastic fiber of the present invention, it can be used for various applications. Specific examples thereof include panties, bras, slips, camisoles, body suits, shorts, girdles, tightening strings for socks, pants, etc., swimsuits, training wear, yoga wear, mountaineering clothes, work clothes, fireworks clothes, clothes for gentlemen and ladies such as suits in combination with natural short fibers, wet suits, leakage prevention tightening members for sanitary products such as paper diapers, artificial skin, artificial blood vessels, artificial hearts, electrical insulating materials, wiping cloths, copy cleaners, gaskets, tightening members for safety clothes, tightening members for laboratory coats, tightening members for waterproof materials, bandages, tightening members for gloves, etc. That is, it can be suitably used in parts that require elastic stretching force.

Examples

[0087] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0088] Each item in the examples was measured by the following methods. For measurements not specifically described regarding the number of evaluations n, the evaluation was carried out with n = 3.

[0089] <DSC measurement> Measured by DSC- The measurement was carried out in MDSC mode using a 2500 instrument manufactured by TA Instruments Japan Co., Ltd. Approximately 5 mg of the cut sample yarn was collected in an aluminum pan, covered with a cover and crimped to obtain a sample. After setting the sample and reference at predetermined positions in the cell, the measurement was carried out under a nitrogen gas flow with a flow rate of 40 Nml / min. It was cooled from room temperature to -90 °C and held for 5 minutes, and then heated to 300 °C at an average heating rate (average scanning rate) of 2 °C / min. The exothermic peak temperature and heat quantity derived from crystallization, and the endothermic peak temperature and heat absorption / evolution quantity derived from melting were measured, and were taken as the crystallization point and melting point (unit: °C), and enthalpy (unit: J / g), respectively.

[0090] <Elongation at break, breaking strength, permanent strain rate, stress relaxation rate, etc.> The breaking elongation, breaking strength, permanent set rate, stress relaxation rate, etc. were measured by subjecting the polyurethane elastic fiber to a tensile test using an Instron 5564 tensile tester.

[0091] A sample with a length of 5 cm (L1) was stretched 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). Next, the length of the sample was held at 300% elongation for 30 seconds, and the stress after holding for 30 seconds was defined 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 on the sixth stretch. The stress at break was defined as (G3), and the sample length at break was defined as (L3). Hereinafter, the above properties are calculated using the following formula. Breaking strength (cN) = (G3) 20 or more: S, 17 or more but less than 20: A, 14 or more but less than 17: B, less than 14: C Breaking elongation (%) = 100 × ((L3) - (L1)) / (L1) 480 or more: S, 460 or more but less than 480: A, 430 or more but less than 460: B, less than 430: C Stress at 200% elongation (cN) = (G+200) 1.2 or more but less than 1.4: S, 1.4 or more but less than 1.5: A, 1.5 or more but less than 1.6: B, over 1.6: C Stress at 200% elongation and recovery = (G-200) 1.2 or more: S, 1.0 or more but less than 1.2: A, 0.8 or more but less than 1.0: B, less than 0.8: C ·Permanent distortion rate (%)=100×((L2)-(L1)) / (L1) Under 20: S, 20 to under 22: A, 22 to under 24: B, 24 or more: C Stress relaxation rate (%) = 100 × ((G1) - (G2)) / (G1) Under 25: S, 25 to under 28: A, 28 to under 31: B, 31 or more: C.

[0092] <Heat resistance> A two-way half tricot consisting of 85% by mass of nylon filament (24 dtex, 7 filaments) and 15% by mass of polyurethane elastic fiber (44 dtex) with an on-machine well count of 9 per inch and an on-machine course count of 18 per inch was produced by a conventional knitting method to form a raw knitted fabric.

[0093] 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 (175°C for 60 seconds, then removed and cooled to room temperature, then dry heat treatment at 180°C for 60 seconds). It was then subjected to a bending tester at a maximum elongation of 20% in both the longitudinal and transverse directions, 2 times per second. Chemical 1 was a mineral oil-based nylon spinning oil containing 1% by mass of oleic acid. Chemical 2 was a copper acetate aqueous solution (copper concentration 100 ppm by mass). The raw knitted fabric to which chemicals 1 and 2 had been applied in this way was a model that reproduced the situation in which trace amounts of machine oil (containing metals) and nylon spinning oil agent had adhered to a nylon stretch raw knitted fabric before dyeing.The amount of chemical 1 adhered to 0.9 g of raw knitted fabric was 3.0 mg, and the amount of chemical 2 adhered to 0.9 g of raw knitted fabric was 3.0 mg. The resulting stretch fabric was dyed in a conventional manner.

[0094] 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 made by five people, and the mode (the judgement that appeared most frequently) was used. If the judgements were split between two people, two people, and one person, the judgement was given as "B." S: No damage and the knitting structure is uniform. A: No damage. B: The fabric is worn and dented, and under magnification the polyurethane elastic fibers are found to be brittle. C: There is a hole in the fabric.

[0095] <Lightfastness, yellowing> After the following exposure treatments (a) and (b), the properties were determined as follows: (A) Ultraviolet (UV) exposure treatment Using a carbon arc 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 sample was exposed to 10 ppm NO2 gas at 40°C and 60% RH for 20 hours. Lightfastness The sample yarn was subjected to the exposure treatment (a) below while being stretched to 100%, and the retention rate of breaking strength thereafter was determined and evaluated as follows.

[0096] 80% or more is S, 60% or more but less than 80% is A, 40% or more but less than 60% is B, and less than 40% is C Yellowing The yellowing property was evaluated by the degree of yellowing (hereinafter abbreviated as Δb) after the samples were exposed to the conditions (a) and (b).

[0097] S for less than 3, A for 3 to 6, B for 6 to 10, C for 10 or more In each exposure treatment, the yellowing index Δb was calculated as follows. Δb = b value after exposure treatment - b value before exposure treatment Measurement of Yellowing: The sample configuration and measurement were as follows. The sample yarn was wound tightly around 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 a standard white surface (JIS Z 8722 4.3.4) were tightly covered with a uniform, flat, transparent glass plate of approximately 1 mm in thickness. The b value was measured in accordance with JIS L 1013 C Method (Hunter's method) using a Hunter color difference meter and calculated based on the following formula. The measurement was made five times, and the average value was used. b=7.0(Y-0.847Z) / Y 1 / 2 (However, X, Y, and Z were calculated according to JIS Z 8701.)

[0098] <Number average molecular weight> The number average molecular weight was measured by GPC under the following conditions. Column: Showa Denko SHODEX KF-806M (2 units) Solvent: N,N-dimethylacetamide 1 ml / min Temperature: 40℃ Detector: Differential refractometer (RI detector).

[0099] <Viscosity> The viscosity was measured at 40° C. using a Model DV-8 falling ball viscometer (Duratech Corp., Waynesboro, VA) according to the method of ASTM D1343-69. The inner diameter of the viscosity tube used was 31.4 (±0.2) mm.

[0100] <Spinning solution stability> The spinning solution was left to stand at 40°C (the temperature of the thermostatic bath of the falling ball viscometer) for 2 hours to stabilize, and then the initial viscosity at 40°C (the viscosity after being left to stand for 2 hours to stabilize) and after being left to stand for 24 hours (another 24 hours had passed) were measured using the method described in <Viscosity> above.

[0101] Then, the viscosity ratio (initial viscosity / viscosity after 24 hours) was calculated from the initial viscosity and the viscosity after 24 hours.

[0102] <Spinning continuity> In dry spinning, the number of times that yarn breakage occurred when a 44 dtex, 4 filament yarn (fiber) was spun continuously for 96 hours was counted and the following evaluation was made. 0 thread breaks = Very good S Number of thread breaks: 1-2 times = Good A Number of thread breaks: 3-4 times = Acceptable B Number of thread breaks: 5 or more = Defective C <Bio content rate> The biomass ratio (mass%) was measured using ISO 16620-2, a method for measuring and identifying the concentration of radioactive carbon (carbon-14).

[0103] <Raw materials used in examples and comparative examples> (Polymer diol having the structure of formula (1)) ·PO3G1: Number average molecular weight 2,000 Polymerization was carried out using 1,3-propanediol with a purity of 99.8% by mass as a raw material by the known method described in JP-A-2003-517082. The melting point was measured by DSC and found to be 15°C.

[0104] (Polymer diol having the structure of formula (2)) ·PO4G1: Number average molecular weight 1,800 The commercially available product Terathane(R) #1800 manufactured by Invista was used.

[0105] (Polymer diol having the structure of formula (3)) PO4G / PO3G-1 It was synthesized by the following procedure.

[0106] Using a mixture of THF, 1,3-propanediol, 1,3-propanediol dimer, and 1,3-propanediol trimer groups as raw materials, PO4G / PO3G-1 having a number average molecular weight of 1900 was polymerized by the known method described in JP-A-2008-503486. The melting point of the obtained PO4G / PO3G-1 measured by DSC was -24°C. PO4G / PO3G-2~4 The following PO4G / PO3G-2 to PO3G-4 were synthesized using the same method as described in the experimental section of the 51st Petroleum and Petrochemical Symposium Abstracts 1F05 (November 2021), with the presence or absence of a solid acid catalyst and the type of catalyst being varied. PO4G / PO3G-2 According to the above-mentioned literature, a mixture of THF and 1,3-propanediol was placed in a round-bottom flask without adding a solid acid catalyst, and the flask was placed under a nitrogen gas atmosphere, sealed, and stirred at 800 rpm at 120°C for 40 hours in a sealed state.

[0107] The c / (c+d) ratio in formula (3) of the resulting polymer diol having a structure of PO4G / PO3G-2 was determined to be 2.4 using a gas chromatograph equipped with a hydrogen flame ionization detector. PO4G / PO3G-3 According to the above-mentioned literature, a mixture of THF, 1,3-propanediol, and amorphous silica alumina as a solid acid catalyst was placed in a round-bottom flask, and after placing it under a nitrogen gas atmosphere, the flask was sealed and stirred at 800 rpm at 120°C for 40 hours in a sealed state.

[0108] The value of c / (c+d) in formula (3) of the resulting polymer diol having a structure of PO4G / PO3G-3 was determined to be 12 using a gas chromatograph equipped with a hydrogen flame ionization detector. PO4G / PO3G-4 According to the above literature, a mixture of THF, 1,3-propanediol, and MFI-type zeolite (SiO2 / Al2O3 molar ratio = 22) manufactured by Tosoh Corporation as a solid acid catalyst was placed in a round-bottom flask, and after placing under a nitrogen gas atmosphere, the flask was sealed and stirred at 800 rpm at 120°C for 40 hours in a sealed state.

[0109] The value of c / (c+d) in formula (3) of the resulting polymer diol having a structure of PO4G / PO3G-4 was determined to be 31 using a gas chromatograph equipped with a hydrogen flame ionization detector.

[0110] (Polymer diols having structures other than those of formulas (1) to (3)) Modified PO4G: Polytetramethylene ether diol with alkyl groups on the side chains It was synthesized by the following procedure.

[0111] 87.5 mol of dehydrated THF 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 mass of perchloric acid and 30% by mass of acetic anhydride). The reaction-completed liquid was neutralized with an aqueous sodium hydroxide solution to obtain a copolymerized tetramethylene ether diol (containing 8.0 mol% of structural units derived from 3-methyl-tetrahydrofuran) having a number average molecular weight of 3,500.

[0112] [Comparative Example 1] (corresponding to the prior art) A vessel was charged with 1.60 moles of 4,4'-MDI and 2,4'-MDI (molar ratio 98:2) per mole of PO4G1 and reacted at 90°C. The resulting reaction product was added to N,N-dimethylacetamide (DMAc) and thoroughly stirred to dissolve. A DMAc solution containing ethylenediamine (EDA) as a chain extender was then added to the reaction product solution, followed by a DMAc solution containing diethylamine as an end-capping agent to prepare a polyurethaneurea solution (PUUX1) with a polymer solids content of 35% by mass. The resulting solution had a viscosity of approximately 2500 poise at 40°C. The polymer had an intrinsic viscosity of 0.95 when measured at 25°C in DMAc at a solution concentration of 0.5 g / 100 ml.

[0113] Next, a 1:1 (mass ratio) mixture of polyurethane ("Methachlor" (registered trademark) 2462 manufactured by DuPont) produced by the reaction of t-butyldiethanolamine and methylene-bis-(4-cyclohexylisocyanate) and a condensation polymer of p-cresol and divinylbenzene ("Methachlor" (registered trademark) 2390 manufactured by DuPont) was used as an antioxidant, and a DMAc solution (35 mass %) of this mixture was prepared to serve as additive solution (B).

[0114] The above solution PUUX1, the additive solution (B), and the nitrogen-containing aromatic compound 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-1,3,5-triazine (C) were uniformly mixed at 99 mass%, 1.0 mass%, and 0.2 mass%, respectively, to form a spinning solution (D).

[0115] The initial viscosity of the spinning solution (D) was 2000 P (poise) (= 190,000 mPa·s), and the viscosity after 24 hours was 2050 P, and the viscosity ratio of these was calculated to be 1.025.

[0116] The spinning solution (D) thus obtained was dry-spun at a dry nitrogen temperature of 300°C or higher so that the DMAc and floating ethylenediamine in the spinning solution were reduced to less than 1 / 100 of the spinning solution content. At this time, the speed ratio of the godet roller to the winder was set to 1:1.20, and a 44 dtex / 4fil multifilament polyurethane elastic fiber was spun. The treatment agent (oil) described below was applied to the spinning solution using an oiling roller before winding. The fiber was wound onto a 58 mm long cylindrical paper tube at a winding speed of 600 m / min via a traverse guide providing a winding width of 38 mm using a surface drive winder, yielding a 500 g wound body. The resulting polyurethane elastic fiber was a coalesced yarn formed by false-twisting four filaments. The oiling roller rotation speed was adjusted so that the desired amount of treatment agent was applied 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 x 10 / s at 25°C -5 m 2 The mixture is 15 parts by mass of mineral oil having a viscosity of 1000000000 / s and 5 parts by mass of magnesium distearate having an average particle size of 0.5 μm.

[0117] The number average molecular weight of the polymer constituting the fiber (or thread) was 22,000. The results, including various evaluations, are shown in the table. [Comparative Example 2] (corresponding to the prior art) Using PO3G1 instead of PO4G1 in Comparative Example 1, a 44 dtex / 4fil multifilament polyurethane elastic fiber was obtained under the same polymerization conditions, additive blending, and spinning conditions as Comparative Example 1.

[0118] The resulting polyurethane solution had a viscosity of about 2400 poise at 40° C. The polymer had an intrinsic viscosity of 1.05 when measured in DMAc at a solution concentration of 0.5 g / 100 ml at 25° C.

[0119] The initial viscosity of the obtained spinning solution was 2100 P (poise) (= 210,000 mPa·s), and the viscosity after 24 hours was 2100 P, and the viscosity ratio of these was calculated to be 1.00.

[0120] The number average molecular weight of the polymer constituting the obtained fiber (or thread) was 24,000. The results, including various evaluations, are shown in the table. [Comparative Example 3] (corresponding to the prior art) A vessel was charged with 1.97 moles of 4,4'-MDI per mole of modified PO4G (copolymerized tetramethylene ether diol, not a polymer diol of formula (1)), and the resulting reaction product was dissolved in N,N-dimethylacetamide (DMAc) with sufficient stirring to obtain a solution. Next, a DMAc solution containing 60 mol% ethylenediamine (EDA) and 40 mol% 1,2-propanediamine (1,2-PDA) as chain extenders was added to the solution containing the reactants, followed by the addition of a DMAc solution containing diethylamine as an end-capping agent, to prepare a polyurethaneurea solution with a polymer solids content of 35% by mass.

[0121] Using the same additive blend and spinning conditions as in Comparative Example 1, a 44 dtex / 4 fil multifilament polyurethane elastic fiber was obtained.

[0122] The resulting polyurethane solution had a viscosity of about 2200 poise at 40° C. The polymer had an intrinsic viscosity of 0.98 measured in DMAc at a solution concentration of 0.5 g / 100 ml at 25° C.

[0123] The initial viscosity of the obtained spinning solution was 2050 P (poise) (= 205,000 mPa·s), and the viscosity after 24 hours was 1950 P, and the viscosity ratio of these was calculated to be 0.95.

[0124] The number average molecular weight of the polymer constituting the resulting polyurethane elastic fiber was 20,000. The results, including various evaluations, are shown in the table. [Examples 1 to 3] A polyurethane urea fiber of 44 dtex was produced in the same manner as in Comparative Example 1, except that PO4G1 and PO3G1 were used as the polymer diol constituents in the proportions shown in Table 1 instead of the polymer diol used in Comparative Example 1.

[0125] The glass transition temperature (Tg) of this polyurethane urea fiber was −71° C. The concentration of effective terminal amines constituting this polyurethane urea fiber was 20 meq / kg. [Examples 4 to 6] As shown in Table 1, based on Examples 1 to 3, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that 1 mass% of PO4G1 and PO3G1 copolymer (PO4G / PO3G-1) was blended into the polymer diol mixture during the synthesis of the polyurethane resin.

[0126] [Examples 7 to 9] As shown in Table 1, based on Examples 1 to 3, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that 10 mass% of PO4G / PO3G-1 was blended into the polymer diol mixture during the synthesis of the polyurethane resin.

[0127] As can be seen from Table 1, the DSC measurement results show that using a mixed polymer diol of PO4G1 and PO3G1 lowers the soft segment melting point compared to when using polymer diols consisting of PO4G1 alone or PO3G1 alone, and similarly reduces the endothermic enthalpy. This is thought to be due to suppression of crystallization. In fact, it can be seen that the mechanical properties, such as stress at 200% elongation and recovery, are improved when using a mixed polymer diol of PO4G1 and PO3G1 compared to when using PO4G1 alone or PO3G1 alone. In other words, as a result, the stress at elongation and stress at elongation and recovery were improved.

[0128] Furthermore, the melting point of the hard segment measured by DSC is higher when using a mixed polymer diol of PO4G1 and PO3G1 than when using polymer diols of PO4G1 alone or PO3G1 alone, and the amount of endothermic enthalpy also tends to be larger. In other words, the separation of the soft segment and hard segment becomes clearer, and the hard segment crystals become stronger. As a result, the breaking strength and breaking elongation increased.

[0129] [Examples 11 to 12] A polyurethane urea fiber of 44 dtex was produced in the same manner as in Comparative Example 1, except that PO4G1 and PO3G1 were used as the polymer diol constituents in the proportions shown in Table 2 instead of the polymer diol.

[0130] [Examples 13 to 16] As shown in Table 2, based on Examples 1 to 3, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that 1 mass% of PO4G / PO3G-2, PO4G / PO3G-3, or PO4G / PO3G-4 was blended into the polymer diol mixture during polyurethane resin synthesis.

[0131] [Examples 17 to 19] As shown in Table 2, based on Examples 1 to 3, polyurethane urea fibers of 44 dtex were produced in the same manner as in Example 1, except that 10 mass% of PO4G / PO3G-2, PO4G / PO3G-3, or PO4G / PO3G-4 was blended into the polymer diol mixture during polyurethane resin synthesis.

[0132] [Table 1]

[0133] [Table 2]

Claims

1. A polyurethane resin composition comprising as a main component a polyurethane resin produced from polymer diol and diisocyanate as starting materials, wherein the polyurethane resin contains, as the starting polymer diol, a polymer diol whose structure, when hydrogen atoms at both ends are removed, is represented by the following formula (1) and a polymer diol whose structure, when hydrogen atoms at both ends are removed, is represented by the following formula (2), in total, at 50 mass% or more of the total polymer diol, and wherein the mass ratios r(1) and r(2) of the structural moieties corresponding to the following formulas (1) and (2), respectively, to the total structural moieties derived from the polymer diol satisfy the following relational formula (A): [Equation 1] 【number】 【number】 In formulas (1) and (2), the bonds marked with * represent: These structural moieties represent bonds with hydrogen atoms in the polymer diol, When these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when they are present at positions other than the terminals of the polyurethane resin, they represent bonds between O and C═O in the urethane bond.

2. The polyurethane resin composition according to claim 1, wherein the starting polymer diol further comprises a polymer diol having a structure represented by the following formula (3) when hydrogen atoms at both ends are removed, and the mass ratio r(3) of the structural moiety corresponding to the following formula (3) to all structural moieties derived from the polymer diol, and the mass ratios r(1) and r(2) satisfy the following relational formula (B): [Equation 2] 【number】 In formula (3), the linkage of the unit structures having the repeating numbers c and d may be in a block or random form, Bonds marked with * are These structural moieties represent bonds with hydrogen atoms in the polymer diol, When these structural moieties are present at the terminals of the polyurethane resin, they represent bonds with hydrogen atoms, and when they are present at positions other than the terminals of the polyurethane resin, they represent bonds between O and C═O in the urethane bond.

3. The polyurethane resin composition according to claim 1, wherein the mass ratios r(1) and r(2) satisfy the following relational formula (A'): [Equation 3]

4. The polyurethane resin composition according to claim 2, wherein the mass ratios r(1), r(2), and r(3) satisfy the following relational formula (B'): [Equation 4]

5. The polyurethane resin composition according to claim 1, wherein the number average molecular weight of the polymer diol as a whole, in which the structure of the portion after removing hydrogen atoms from both ends is represented by any one of formulas (1) to (3), is 1,000 or more and 30,000 or less, and the ratio of the number average molecular weight of the polymer diol as a part after removing hydrogen atoms from both ends, in which the structure of the portion after removing hydrogen atoms from both ends is represented by formula (2), to the number average molecular weight of the polymer diol as a part after removing hydrogen atoms from both ends, in which the structure of the portion after removing hydrogen atoms from both ends is represented by formula (1) is 1.00 to 1.

16.

6. 2. The polyurethane resin composition according to claim 1, wherein the biocontent is 3% or more in terms of carbon mass ratio, as determined by carbon isotope ratio measurement according to ISO 16620-2.

7. A polyurethane elastic fiber comprising the resin composition of any one of claims 1 to 6.

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