Polyurethane resin composition and polyurethane elastic fiber

Abstract

[Problem] To provide a highly durable polyurethane elastic fiber having high stress during contraction, that is, recovery stress, and excellent breaking stretching strength [Resolution Means] A polyurethane resin composition using as a main component a polyurethane resin using a polymer diol and a diisocyanate as starting materials, wherein the polyurethane resin contains, as the starting material polymer diol, a 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 whose structure of a portion other than a hydrogen at both ends is represented by the following formula (2) at a total of 50 mass% or more of the entire polymer diol, and mass ratios r(1) and r(2) of structural parts respectively corresponding to the following formulas (1) and (2) to the total structural parts derived from polymer diols satisfy the following relational formula (A). [Math. 1] 0.1≦r(1) / (r(1)+r(2))≦0.9 (A) [Chem. 1] *-O(CH2CH2CH2-O)a-* (1) [Chem. 2] *-O(CH2CH2CH2CH2-O)b-* (2) In formulas (1) and (2), for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

Description

[0001] POLYURETHANE RESIN COMPOSITION AND POLYURETHANE ELASTIC FIBER

[0002] [Technical Field]

[0003] The present invention relates to a polyurethane resin composition and a polyurethane elastic fiber and particularly relates to a polyurethane elastic fiber having high stress during contraction, that is, high recovery stress, as well as high durability.

[0004] [Background Art]

[0005] Polyurethane resins have excellent stretchability and thus are widely deployed in laminate films, coating agents, sealing materials, glues, adhesives, fiber processing agents, paints, artificial leathers and synthetic leathers, raw materials for elastomers such as rollers, fiber products, and the like. In each application, in order to prevent deterioration due to thermal history when producing or processing a final product using polyurethane resin as a raw material and to improve the durability of the final product, improvements in heat resistance while maintaining stretchability (high elastic recovery and a high degree of elongation) of polyurethane resin are required.

[0006] Polyurethane elastic fibers are widely used in stretchable clothing applications such as legwear, innerwear, and sportswear and in industrial materials due to their excellent stretchability.

[0007] Similarly, polyurethane elastic fibers are required to have high elastic recovery, high stretching strength, high heat resistance, and thermosetting properties. In particular, the improvement of recovery stress has consistently been sought after in regard to elastic recovery performance.

[0008] In techniques for obtaining high elastic recovery performance, it is important to suppress stress induced crystallization (stress induced crystallization) of a soft segment. Conventionally, techniques have been disclosed for imparting irregularity to a polymer main chain in the soft segment. For example, it is known that in a polyurethane structure consisting of a copolyether diol of tetrahydrofuran (THF) and 3 -alkyltetrahydrofuran and a diisocyanate, and a polyurethane structure consisting of a copolyether diol of tetrahydrofuran and 2 -alkyltetrahydrofuran and a diisocyanate, a soft segment may be obtained having a higher stress during contraction, that is a higher recovery stress, compared to a polyether diol of tetrahydrofuran alone (referred to as poly tetramethylene ether diol, PTMG, PO4G, or the like) (Patent Documents 1 and 2). Also disclosed is a technique of mixing different types of polymer main chains in the soft segment. For example, it is known that in a polyurethane structure consisting of a polymer diol in which PTMG and a polypropylene ether (PPG) are mixed and a diisocyanate, and a polyurethane structure consisting of a polymer diol of copolymerized tetrahydrofuran and ethylene oxide and diisocyanate, a soft segment may be obtained having a higher recovery stress (Patent Documents 3 and 4).

[0009] Moreover, in recent years, with growing interest in various environmental issues, there has been a demand for initiatives oriented toward a transition to a sustainable society for all organic materials, and polyurethane elastic fibers, which are contained at a relatively low content in stretching members, are no exception. Since the content in stretchable clothing and industrial materials is relatively low, it is difficult to separate and remove such, making it difficult to recycle resources, and thermal recycling may be preferable. Therefore, the use of components derived from carbon-neutral biomass resources as raw materials has been proposed (Patent Documents 5 and 6).

[0010] [Prior Art Documents]

[0011] [Patent Documents]

[0012] [Patent Document 1] JP H2-19511 A

[0013] [Patent Document 2] JP 2022-79647 A

[0014] [Patent Document 3] JP 2001-505596 A (Translation of PCT Application)

[0015] [Patent Document 4] JP 2001-226823 A

[0016] [Patent Document 5] JP 2014-522446 A (Translation of PCT Application)

[0017] [Patent Document 6] JP 2021-152139 A

[0018] [Summary of Invention]

[0019] [Problem to Be Solved by Invention]

[0020] However, polyurethane elastic fibers obtained by spinning a polyurethane resin composition of such conventional art have insufficient recovery stress and breaking stretching strength. Thus, there is demand for a polyurethane resin composition which can impart a polyurethane elastic fiber having high recovery stress and high breaking stretching strength and for a polyurethane elastic fiber.

[0021] A problem of the present invention is to provide a polyurethane resin composition which can impart a highly durable polyurethane elastic fiber having high stress during contraction, that is, recovery stress, and high breaking stretching strength, and a polyurethane elastic fiber.

[0022] [Means for Solving Problem]

[0023] To address this problem, the inventors have studied the compatibility of linear methylene ethers having 2 to 6 carbons as a technique for mixing different types of polymer main chains. Similar studies have been disclosed on polyamide resins (JP 2009-526892 A (Translation of PCT Application), JP 2016-532728 A (Translation of PCT Application), and the like), but there have been few studies on polyurethane resins. That is, a mixture of two 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 have found that a combination of polytrimethylene ether glycol and poly tetramethylene ether glycol results in specific improvements in recovery stress and breaking stretching strength, and have arrived at the present invention. Furthermore, when a block or random copolymer containing repeating units of trimethylene ether and tetramethylene ether is contained, compatibilization is promoted, and more specific improvements in recovery stress and breaking stretching strength have been found. That is, a specific improvement in recovery stress and breaking stretching strength was found by mixing three alkylene ether glycols by a polycondensation of polytrimethylene ether glycol, polytetramethylene ether glycol, 1,3- propanediol, and tetrahydrofuran.

[0024] That is, the present invention has a configuration as follows.

[0025] [1] A polyurethane resin composition using as a main component a polyurethane resin using a polymer diol and a diisocyanate as starting materials, wherein the polyurethane resin contains, as the starting material polymer diol, a 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 whose structure of a portion other than a hydrogen at both ends is represented by the following formula (2) at a total of 50 mass% or more of the entire polymer diol, and mass ratios r(l) and r(2) of structural parts respectively corresponding to the following formulas (1) and (2) to the total structural parts derived from polymer diols satisfy the following relational formula (A).

[0026] [Math. 1]

[0027] 0.1 ^r(l) / (r(l)+r(2)) ^0.9 (A)

[0028] [Chem. 1]

[0029] *-O(CH2CH2CH2-O)a-* (1)

[0030] [Chem. 2]

[0031] *-O(CH2CH2CH2CH2-O)b-* (2)

[0032] In formulas (1) and (2), for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

[0033] [2] The polyurethane resin composition according to [1], wherein further contained as the starting material polymer diol is a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the following formula (3), and a mass ratio r(3) of a structural part corresponding to the following formula (3) to the total structural parts derived from polymer diols and the mass ratios r(l) and r(2) satisfy the following relational formula (B).

[0034] [Math. 2]

[0035] 0.001 ^r(3) / (r(l)+r(2)+r(3)) 0.3 (B)

[0036] [Chem. 3]

[0037] *-O(CH2CH2CH2-O)c-(CH2CH2CH2CH2-O)d-* (3)

[0038] In formula (3), linkage of unit structures having a number of repeating c and d may be in block or random form, and for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

[0039] [3] The polyurethane resin composition according to [1] or [2], wherein the mass ratios r(l) and r(2) satisfy the following relational formula (A').

[0040] [Math. 3]

[0041] 0.1 ^r(l) / (r(l)+r(2)) ^0.6 (A’)

[0042] [4] The polyurethane resin composition according to [2], wherein the mass ratios r(l), r(2), and r(3) satisfy the following relational formula (B’).

[0043] [Math. 4]

[0044] 0.005 ^r(3) / (r(l)+r(2)+r(3))^0.15 (B’)

[0045] [5] The polyurethane resin composition according to any of [1] to [4], wherein, when taking polymer diols whose structure of a portion other than a hydrogen at both ends is represented by the following formulas (1) to (3) as the whole, a number average molecular weight is 1,000 or more and 30,000 or less, and a ratio of a number average molecular weight of a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the formula (2) to a number average molecular weight of a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the formula (1) is 1.00 to 1.16.

[0046] [6] The polyurethane resin composition according to any of [1] to [5], wherein the bio-based content by carbon isotope ratio measurement established in ISO 16620-2 is 3% or more in a carbon mass ratio.

[0047] [7] A polyurethane elastic fiber consisting of the resin composition according to any of [1] to [6].

[0048] [Effect of Invention]

[0049] According to the present invention, it is possible to provide a polyurethane resin composition which can impart a highly durable polyurethane elastic fiber having high stress during contraction, that is, recovery stress, and high breaking stretching strength, and a polyurethane elastic fiber.

[0050] [Embodiments of Invention]

[0051] The present invention will be described in detail below along with embodiments.

[0052] First, a polyurethane used in a polyurethane resin composition and polyurethane elastic fiber of the present invention will be described. The polyurethane described herein is preferably used as a main constituent component, and the term main constituent component as used herein is a component contained in the polyurethane resin composition and the polyurethane elastic fiber in excess of 50 mass%.

[0053] The polyurethane used in the present invention has a polyether structure in its backbone. The polyurethane having a polyether structure in its backbone has a structure that includes as a starting material at least a polymer diol having a polyether structure. Here, the phrase "has a structure that includes as a starting material" refers to a structure of the relevant portion of the starting material in order to describe the backbone structure of the polymer, and the starting material and synthesis method thereof are not particularly limited. That is, the starting material may be, for example, 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 may be a polyurethane urethane composed of a polymer diol having a polyether structure, 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 amino group in the molecule as a chain extender. It is also preferable that trifunctional or higher polyfunctional glycols, isocyanates, or the like be used to the extent that they do not impede the effects of the present invention.

[0054] In the present invention, the polymer diol having a polyether structure contains a 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 whose structure of a portion other than a hydrogen at both ends is represented by the following formula (2) at a total of 50 mass% or more of the entire polymer diol.

[0055] [Chem. 4] *-O(CH2CH2CH2-O)a-* (1)

[0056] [Chem. 5]

[0057] *-O(CH2CH2CH2CH2-O)b-* (2)

[0058] Note that in formulas (1) and (2), a and b are integers and for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

[0059] Furthermore, it is essential that mass ratios r(l) and r(2) of structural parts respectively corresponding to the formulas (1) and (2) to the total structural parts derived from polymer diols satisfy the following relational formula (A)

[0060] [Math. 5]

[0061] 0.1 ^r(l) / (r(l)+r(2)) ^0.9 (A)

[0062] Note that in the present specification, "polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the formula (n)" may be abbreviated as "polymer diol having a structure of formula (n)."

[0063] It has been found that, when the polyurethane resin contained as a main component in the polyurethane resin composition of the present invention satisfies the above relational formula (A), a soft segment melting point of the polyurethane elastic fiber composed of the polyurethane resin composition as measured by a differential scanning calorimeter (DSC) is lower than when using polyurethane resins which respectively use the polymer diols having a structure of formula (1) or (2) alone as a starting material, and an amount of endothermic enthalpy is also smaller. This is preferable because, when the polyurethane resin composition of the present invention is spun to obtain a polyurethane elastic fiber, crystallization of the structural parts represented by formulas (1) and (2) in the polyurethane elastic fiber is suppressed, resulting in a favorable balance between stress during elongation and stress during elongation recovery. Hereinafter, "polyurethane resin contained as a main component in the polyurethane resin composition of the present invention" may be abbreviated as "polyurethane resin in the present invention."

[0064] It has been found that, when the polyurethane resin in the present invention satisfies the above relational formula (A), a hard segment melting point of the polyurethane elastic fiber as measured by DSC is higher than when using polyurethane resins which respectively use the polymer diols having a structure of formula (1) or (2) alone as a starting material, and an amount of endothermic enthalpy also tends to be larger. This is believed to be because the separation of the soft segment and the hard segment becomes clearer and the hard segment crystals become stronger, and as a result, an effect is obtained of increasing breaking strength and breaking elongation.

[0065] Furthermore, when the polyurethane resin in the present invention satisfies the following relational formula (A'), the balance of stress during elongation recovery, as well as the breaking strength and breaking elongation of the formed body obtained from the polyurethane resin composition and the polyurethane elastic fiber are more preferable.

[0066] [Math. 6]

[0067] 0.1 ^r(l) / (r(l)+r(2)) ^0.6 (A’)

[0068] Furthermore, as a method to obtain further improvement of the balance of stress during elongation and recovery and the breaking strength and breaking elongation described above, it is more preferable that the starting material polymer diol further contains a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the following formula (3).

[0069] [Chem. 6]

[0070] *-O(CH2CH2CH2-O)c-(CH2CH2CH2CH2-O)d-* (3)

[0071] Here, formula (3) is a composition formula indicating a content ratio of unit structures, and c and d each represent only the content ratio of the unit structures. That is, the respective unit structures (CH2CH2CH2-O) and (CH2CH2CH2CH2-O) may be linked in block or random form. From the viewpoint of achieving more effective compatibilization, a random form is more preferable. Furthermore, in structural parts indicated in formula (3), for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

[0072] By including a polymer diol having a structure of formula (3) as a starting material polymer diol, a moiety of a structure of formula (1) and a moiety of a structure of formula (2) in the polyurethane resin in the present invention are made compatible with each other, and in a polyurethane elastic fiber composed of a polyurethane resin composition using such a polyurethane resin as a main component, the effect due to crystallization of the soft segment and hard segment in the polyurethane elastic fiber confirmed by the above-mentioned DSC becomes more pronounced, which is believed to be why the balance of stress during elongation recovery and the breaking strength and breaking elongation may be further improved.

[0073] The starting material polymer diol further contains a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by formula (3), and the mass ratio r(3) of a structural part corresponding to formula (3) to the total structural parts derived from polymer diols and the mass ratios r(l) and r(2) satisfy the following relational formula (B), whereby the balance of stress during elongation recovery and the breaking strength and breaking elongation of the polyurethane elastic fiber composed of the polyurethane resin composition using such a polyurethane resin as a main component become more preferable, and furthermore, spinning solution stability and spinning continuity become preferable.

[0074] [Math. 7]

[0075] 0.001 ^r(3) / (r(l)+r(2)+r(3)) 0.3 (B)

[0076] The above-mentioned effect is more pronounced when the following relational formula (B') is satisfied, which is more preferable. [Math. 8]

[0077] 0.005 ^r(3) / (r(l)+r(2)+r(3))^0.15 (B’)

[0078] From the perspective of obtaining elongation, strength, heat resistance, and the like when making the polyurethane elastic fiber, when taking polymer diols whose structure of a portion other than a hydrogen at both ends is represented by the following formulas (1) to (3) as the whole, a number average molecular weight of the starting material of the polyurethane resin in the present invention is preferably 1,000 or more and more preferably 1,800 or more. By using a polymer diol having a number average molecular weight in this range, it is possible to obtain a polyurethane resin composition which can impart a polyurethane elastic fiber having more excellent elongation, strength, and heat resistance. Furthermore, this number average molecular weight is preferably 30,000 or less, and more preferably 10,000 or less. By using a polymer diol having a number average molecular weight in this range, it is possible to obtain a polyurethane resin composition which can impart a polyurethane elastic fiber having more excellent elongation, elastic recovery, and heat resistance.

[0079] The number average molecular weight of the polymer diol having a structure of formula (1) is preferably 8% ± 8% larger than the number average molecular weight of the polymer diol having a structure of formula (2). That is, when the ratio of the number average molecular weight of the polymer diol having a structure of formula (2) to the number average molecular weight of the polymer diol having a structure of formula (1) is 1.00 to 1.16, soft segment lengths at maximum elongation become uniform, whereby the balance of stress during elongation recovery, as well as breaking strength and breaking elongation, become more favorable. For example, when the number average molecular weight of the polymer diol having a structure of formula (1) is 1,800, a theoretical molecular chain length at maximum elongation is 12.2 nm, and a theoretical number average molecular weight of the polymer diol having a structure of formula (2) of 12.2 nm is about 2,000.

[0080] It is also more preferable that the number average molecular weight of the polymer diol having a structure of formula (3) is an intermediate value between the number average molecular weight of the polymer diol having a structure of formula (1) and the number average molecular weight of the polymer diol having a structure of formula (2). The balance of stress during elongation recovery, as well as the breaking strength and breaking elongation, become more favorable, and as such, polymerization stability and stability of the spinning solution are improved.

[0081] Moreover, as a raw material for structural units of formula (1) and formula (2), it is preferable to use a component derived from carbon-neutral biomass resources suitable for thermal recycling. In such a case, a degree to which components derived from biomass resources are used as raw materials is expressed as the bio-based content. The bio-based content may be obtained using ISO 16620-2, which is a radiocarbon (carbon- 14) concentration measurement identification method. In the present invention, the radioactive carbon (carbon- 14) concentration measurement identification method of ISO 16620-2 described above may be simply referred to as carbon isotope ratio measurement. It is preferable that the polyurethane resin composition and polyurethane elastic fiber of the present invention have a bio-based content of 3% or more in carbon mass ratio as determined by carbon isotope ratio measurement.

[0082] For a polymer diol other than the polymer diols having a structure of formulas (1) to (3), it is preferable to include one having a structure of a polyether-based, polyester-based diol, polycarbonate diol, or the like. Furthermore, from the perspective of imparting particularly flexibility and elongation to a formed body obtained from the polyurethane resin composition of the present invention and the polyurethane elastic fiber obtained from the polyurethane resin composition of the present invention, it is preferable to use a polyether-based diol. Furthermore, two or more types of these polymer diols may be used in combination.

[0083] For the molecular weight of polymer diols other than the polymer diols having a structure of formulas (1) to (3), from the perspective of obtaining elongation, strength, heat resistance, and the like when making an elastic fiber, a number average molecular weight of 1,000 or more is preferable and 3,000 or more is more preferable. By using a polyol having a number average molecular weight in this range, it is possible to obtain a polyurethane elastic fiber having excellent elongation, strength, and heat resistance. Furthermore, the number average molecular weight is preferably 30,000 or less, and more preferably 10,000 or less. By using a polyol having a number average molecular weight in this range, it is possible to obtain a polyurethane elastic fiber having excellent elongation, elastic recovery, and heat resistance.

[0084] Next, as the diisocyanate, aromatic diisocyanates such as diphenylmethane diisocyanate (hereinafter also abbreviated as MDI), tolylene diisocyanate, benzene 1,4-diisocyanate, xylylene diisocyanate, or 2,6-naphthalene diisocyanate, are suitable for synthesizing polyurethane having particularly high heat resistance and strength. Moreover, as an alicyclic diisocyanate, for example, methylenebis(cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane 2,4- diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, octahydro 1,5 -naphthalene diisocyanate, and the like are preferable. Alicyclic diisocyanates may be particularly effectively used to suppress yellowing of a formed body 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. Furthermore, these diisocyanates may be used alone, or two or more types may be combined. Hereinafter, a formed body obtained from the polyurethane resin composition may be referred to as a polyurethane resin formed body.

[0085] Next, for a chain extender used when synthesizing a polyurethane, it is preferable that at least one type of low molecular weight diamine or low molecular weight diol is used. Note that a type having both a hydroxyl group and an amino group in one molecule, such as ethanolamine, may be used.

[0086] Examples of preferable low molecular weight diamines include ethylenediamine, 1,2- propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p- xylylenediamine, m-xylylenediamine, p,p'-methylenedianiline, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, bis(4- aminophenyl)phosphine oxide, and the like. It is preferable to use one or two or more of these.

[0087] Ethylenediamine is particularly preferable. By using ethylenediamine, it is possible to easily obtain a polyurethane elastic fiber having excellent elongation, elastic recovery, as well as heat resistance.

[0088] A triamine compound capable of forming a cross-linked structure in these chain extenders, for example, diethylenetriamine and the like may be added to an extent that the effect is not lost.

[0089] Furthermore, typical examples of low molecular weight diols include ethylene glycol, 1,3- propanediol, 1,4-butanediol, bishydroxy ethoxy benzene, bishydroxy ethylene terephthalate, and 1- methyl-l,2-ethanediol. It is preferable to use one or two or more of these. Particularly preferably, are ethylene glycol, 1,3 -propanediol, and 1,4-butanediol. When these are used, heat resistance increases as a polyurethane having diol elongation, and it is possible to obtain a polyurethane resin formed body and an elastic fiber having higher strength.

[0090] Furthermore, the molecular weight of the polyurethane in the present invention, from the perspective of obtaining a polyurethane resin formed body and polyurethane elastic fiber having high durability and strength, is preferably within a range of 30,000 or more and 150,000 or less in terms of the number average molecular weight. Note that the number average molecular weight is measured by GPC and converted using polystyrene.

[0091] It is also preferable that one type or two or more types of terminal sequestering agents in combination be used in the polyurethane resin. Preferable examples of terminal sequestering 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 phenyl isocyanate.

[0092] The polyurethane resin composition and polyurethane elastic fiber of the present invention preferably a nitrogen-containing aromatic compound at 0.05 mass% or more and 2.0 mass% or less. Durability, and particularly high durability having excellent antioxidative properties, is synergistically exhibited with the polyurethane having a polyether structure of the general formulas (1) and (2) in the backbone. When the content of the nitrogen-containing aromatic compound is less than 0.05 mass%, there is a risk that durability of the polyurethane resin formed body and the polyurethane elastic fiber will be insufficient, and when the content exceeds 2.0 mass%, a reduction in heat resistance of the polyurethane resin formed body and the polyurethane elastic fiber becomes pronounced, and there is a risk that yellowing resistance is reduced.

[0093] More specifically, the contained nitrogen-containing aromatic compound is a compound having a nitrogen-containing aromatic heterocyclic ring in which nitrogen atoms are arranged on an aromatic ring in the molecule. Examples of chemical structural backbones include: pyrrole, pyridine, carbazole, and quinoline, which have a one-nitrogen aromatic heterocyclic ring; imidazole, pyrazole, pyridazine, pyrazine, pyrimidine, naphthyridine, and phenanthroline, which have a two-nitrogen aromatic heterocyclic ring; triazine, benzotriazole, and naphthyridine, which have a three-nitrogen aromatic heterocyclic ring; and the like, and heteroatoms other than nitrogen may also be arranged, such as in benzothiazole and benzoxazole. As specific examples of such a nitrogen-containing aromatic compound, benzotriazole compounds and triazine compounds known as ultraviolet light absorbers are preferable, and specific examples of compounds include 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-2-hydroxyphenyl)-5- chlorobenzo triazole, 2-(2-hydroxy-3,5-bisphenyl)benzotriazole, 2,4-di(2', 4'-dimethylphenyl)-6- (2"-hydroxy-4"-alkoxyphenyl)-l,3,5-triazine, and 2,2'-(l,4-phenylene)bis[4H-3,l-benzoxazin-4- one]. Examples of product names include: "Tinuvin"-P, "Tinuvin"-213, "Tinuvin"-234, "Tinuvin"- 327, "Tinuvin"-328, "Tinuvin"-571, and "Tinuvin"-1577 manufactured by Ciba-Geigy; "Sumisorb" 250 manufactured by Sumitomo Chemical Co., Ltd.; "Cyasorb" UV-5411, UV-1164, and UV-3638 manufactured by American Cyanamid; " Adeka Stab" LA-31 manufactured by Adeka Corporation; and the like.

[0094] In the polyurethane elastic fiber, a value of 0.05 mass% or more and 2.0 mass% or less of the content of the nitrogen-containing aromatic compound generally corresponds to the nitrogencontaining aromatic compound being present in a range of 0.25 to 13.3 milliequivalents (meq / kg) in 1 kg of polyurethane elastic fiber. In contrast, because an aromatic ring containing a nitrogen atom easily undergoes thermal decomposition, when the content of the nitrogen-containing aromatic compound is too high (that is, when the aromatic ring nitrogen atom exceeds 13.3 milliequivalents), radical generation due to thermal decomposition becomes more dominant than the synergistic effect of polyurethane having the polyether structure of general formula (1) in its backbone, heat resistance is reduced, and a quinone structure is formed, causing thermal discoloration, so a function such as high heat resistance may not be obtainable. Furthermore, a nitrogen-containing aromatic compound may be included in a large amount as a light resistant agent, and the content of the nitrogen-containing aromatic compound is preferably 0.1 mass% or more and 0.6 mass% or less.

[0095] In order to make a polyurethane elastic fiber that simultaneously exhibits high heat resistance, resistance to unsaturated fatty acids, and resistance to heavy metals during dyeing, as well as having high elastic recovery and high stretching strength, from the perspective of suppressing volatilization loss during spinning, among nitrogen-containing aromatic compounds a compound group of molecular weight 300 or more is preferable. Furthermore, from the perspective of improving heat resistance and spinnability during dyeing, it is more preferable that the compound have two or more nitrogen atoms in the aromatic ring, and this is assumed to facilitate the formation of a complex with a heavy metal and to demonstrate a chelating effect. Furthermore, in order to sufficiently exhibit this effect, the chemical structural backbone of the nitrogen-containing aromatic compound is preferably triazine. Note that it is preferable that testing be conducted in advance depending on the molecular weight of the nitrogen-containing aromatic compound which is actually to be used, as well as the number of effective nitrogen atoms in the aromatic ring, the application, and the like, and that an optimal value be appropriately determined.

[0096] Furthermore, in order to make the polyurethane elastic fiber having particularly high heat resistance during dying, 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-l,3,5- triazine is preferred as the nitrogen-containing aromatic compound.

[0097] Furthermore, from the perspective of the compound used as the nitrogen-containing aromatic compound accelerating dispersion and dissolution into the polyurethane resin when making the polyurethane resin composition, and imparting desired properties to the polyurethane elastic fiber produced thereby and furthermore being able to make a polyurethane elastic fiber of an appropriate transparency, and furthermore, not causing discoloration and yellowing of the polyurethane elastic fiber while not reducing the content of these compounds even when subjected to heat or the like in a spinning step, a liquid compound having a viscosity at 20°C of 100 cP or more and 10,000 P or less is preferable.

[0098] Additionally, in the present invention, various stabilizers other than those mentioned above, such as hindered phenol-based, sulfur-based, and phosphorus-based antioxidants, hindered amine- based, triazole-based, benzophenone-based, benzoate-based, nickel-based, and salicylic -based light stabilizers, antistatic agents, lubricants, molecular regulators such as peroxides, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, fluorescent brightening agents, fillers, flame retardants, flame retardant aids, pigments, and the like may be contained in the polyurethane elastic fiber or polyurethane spinning solution within a range that do not impede the effects of the present invention. For example, it is preferable that a light resistant agent and antioxidant contain: 2,6-di-t-butyl-p-cresol (BHT) and benzophenone -based drugs, various hindered amine-based drugs, 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, disinfectants, deodorants, antibacterial agents containing silver, zinc, compounds of these or the like, lubricants such as silicone and mineral oil, and various antistatic agents such as barium sulfate, cerium oxide, betaine, and phosphoric acid-based agents. It is also preferable to react these with the polymer. Furthermore, nitric oxide scavengers such as HN-130 and HN-150 manufactured by Japan Finechem Company, for example, are preferably used to further increase durability, particularly to light and various types of nitric oxides and the like.

[0099] Furthermore, from the perspective of facilitating an increase in spinning speed during a dry spinning process, fine particles of a metal oxide such as titanium dioxide, zinc oxide, or the like may be added to the spinning dope. Furthermore, from the perspective of improving heat resistance and functionality, inorganic materials and inorganic porous materials (for example, bamboo charcoal, charcoal, carbon black, porous mud, clay, diatomaceous earth, coconut shell activated carbon, coal-based activated carbon, zeolite, pearlite, and the like) may be added within a range that does not inhibit the effect of the present invention. These additives may be added when preparing the spinning dope by mixing a polyurethane solution and the above modifiers, or may be included beforehand in the polyurethane solution or dispersion before mixing. The content of these additives is appropriately determined according to an object and the like.

[0100] In the polyurethane elastic fiber of the present invention, when an antioxidant is included, a content of 0.002 mass% or more and 5.0 mass% or less is preferable. When the content of the antioxidant is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable antioxidants are hindered phenol compounds, and examples include phenol compounds generally known as antioxidants. For example, 3,5-di-t-butyl-4-hydroxy-toluene, n- octadecyl-P-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis[methylene-3-(3',5'-di-t-butyl- 4'-hydroxyphenyl)propionate]methane, l,3,5-trimethyl-2,4,6'-tris(3,5-di-t-butyl-4- hydroxybenzyljbenzene, 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[l,l-dimethyl- 2- { P-(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- hydroxyphcny Ijpropionatc], 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 , l-bis(2-methyl-5-t-butyl-4-hydroxyphenyl)butane, 1 , 1 ,3-tris(2- methyl-5-t-butyl-4-hydroxyphenyl)butane, l,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine -2,4,6(lH,3H,5H)-trione, l,3,5-tris(3'-t-butyl-4'-hydroxy-5-methylbenzyl)-S-triazine-

[0101] 2,4,6(lH,3H,5H)-trione, l,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-l,3,5-triazine-2,4,6 (lH,3H,5H)-trione, and furthermore, hindered phenol compounds known as antioxidants for polyurethane elastic fibers are also suitably used.

[0102] Preferable specific examples of such a hindered phenol compound include an addition polymer of divinylbenzene and cresol, an addition polymer isobutylene adduct of dicyclopentadiene and cresol, and a polymer of chloromethylstyrene and a compound such as cresol, ethylphenol, t- butylphenol or the like. Here, divinylbenzene and chloromethylstyrene may be p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be any of o-, m-, or p-.

[0103] Among these, from the perspective of stabilizing the viscosity of the raw material spinning solution of the polyurethane elastic fiber, suppressing volatilization loss during spinning, and obtaining favorable spinning properties, it is preferable that the compound have a molecular weight of 300 or more, and furthermore, in order to efficiently exhibit high spinning speed, heat resistance during dyeing, resistance to unsaturated fatty acids, and resistance to heavy metals, one or a combination of polymers having a repeating number of 6 to 12, which is an adduct of l,3,5-tris(4- t-butyl-3-hydroxy-2,6-dimethylbenzyl)-l,3,5-triazin-2,4,6(lH,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] butylate), divinylbenzene, and p-cresol, is preferably used. Among these, 1,3,5- tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-l,3,5-triazine-2,4,6(lH,3H,5H)-trione is particularly preferable. Furthermore, when a triazine compound is selected as compound (a) and compound (c), a particularly high synergistic effect may be obtained in terms of heat resistance during dyeing. Among these, it is particularly preferable that the compound (a) be l,3,5-tris(4-t- butyl-3-hydroxy-2,6-dimethylbenzyl)-l,3,5-triazine-2,4,6(lH,3H,5H)-trione and the compound (c) be 2,4-di(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-alkoxyphenyl)-l,3,5-triazine.

[0104] Furthermore, from the perspective of heat resistance, combined durability, light resistance, and suppression of the reduction of various types of durability due to oxidation such as yellowing, a partially hindered phenol compound is preferably included in the polyurethane elastic fiber of the present invention. The partially hindered phenol compound is preferably a compound containing at least two partially hindered hydroxyphenyl groups and having a backbone selected from bisesters and alkylidenes. Here, the alkyl group present at the ring position adjacent to the hydroxyl group in the hydroxyphenyl group is more preferably a tertiary butyl group, and the equivalent of the hydroxyl group is further preferably 600 or less.

[0105] Including the foregoing partially hindered phenol compound may enhance the property reduction suppressing effect. Furthermore, this type of hindered phenol compound acts to specifically suppress the molecular weight of the polyurethane resin constituting the polyurethane elastic fiber and is effective when washing and bleaching are performed at a high frequency, such as for underwear. From the perspective of making this effect sufficient and not adversely affecting physical properties of the fiber, the partially hindered phenol compound is preferably contained at 0.15 to 4 mass% relative to the polyurethane elastic fiber and more preferably contained at 0.5 to 3.5 mass%, and breaking stretching strength, combined durability, yellowing resistance, and in some cases, light resistance, are ensured. A more preferable content of the antioxidant is in the range of 0.2 mass% or more and 3.0 mass% or less, and further preferably in the range of 0.5 mass% or more and 2.0 mass% or less.

[0106] Furthermore, the content of the antioxidant in the polyurethane elastic fiber is preferably in the range of 0.1 mass% or more and 5.0 mass% or less. 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 in the polyurethane elastic fiber that is ultimately produced to the desired content of the antioxidant described above. The content of the antioxidant in the polyurethane elastic fiber is more preferably 0.2 mass% or more and 3.0 mass% or less, and further preferably in the range of 0.5 mass% or more and 2.0 mass% or less.

[0107] More specifically, a hindered phenol compound having a molecular weight of 1,000 is the contained antioxidant, and a hindered phenol compound of molecular weight 1,000 or more which is known as an antioxidant for a polyurethane elastic fiber is preferably used. There are no particular restrictions other than having a relatively high molecular weight of 1,000 or more, and preferable specific examples of such a high molecular weight hindered phenol compound include an addition polymer of divinylbenzene and cresol, an addition polymer isobutylene adduct of dicyclopentadiene and cresol, and a polymer of chloromethylstyrene and a compound such as cresol, ethylphenol, t-butylphenol or the like. Here, divinylbenzene and chloromethylstyrene may be p- or m-. Furthermore, cresol, ethylphenol, and t-butylphenol may be any of o-, m-, or p-.

[0108] Among these, from the perspective of stabilizing the viscosity of the raw material spinning solution of the polyurethane elastic fiber and obtaining favorable spinnability, a hindered phenol compound of a polymer 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 include a certain large amount of the high molecular weight hindered phenol compound, however, from the perspective of obtaining more favorable basic properties as a polyurethane elastic fiber, it is preferable that this not be too much.

[0109] In the polyurethane elastic fiber of the present invention, the content of a degradation product of the antioxidant described above is preferably regulated to 1.0 mass% or less. When the content of the degradation product of the antioxidant is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable breaking stretching strength, resistance to discoloration, and durability are ensured. A preferred content of the degradation product of the antioxidant is in the range of 1.0 mass% or less, and more preferably in the range of 0.5 mass% or less.

[0110] In the polyurethane resin composition of the present invention, a tertiary amine compound is preferably contained. The polyurethane resin composition containing the tertiary amine compound makes it possible to enhance the performance of the polyurethane elastic fiber obtained by spinning the polyurethane resin composition, particularly yellowing prevention performance. From the perspective of making this effect sufficient and of not adversely affecting the physical properties of the fiber, the tertiary amine compound is preferably contained at 0.2 mass% or more and 5.0 mass% or less and more preferably contained at 0.5 mass% or more and 4.0 mass% or less relative to the mass of the polyurethane resin composition. 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 further preferably in the range of 0.5 mass% or more and 2.0 mass% or less.

[0111] In the polyurethane elastic fiber of the present invention as well, when a tertiary amine compound is contained, a content is preferably 0.2 mass% or more and 5.0 mass% or less, and a more preferable range is similar to that of the polyurethane resin composition. When the content of the tertiary amine compound is within this range, practically preferable properties of the polyurethane elastic fiber, spinnability, dyeability, durability, and yellowing resistance are improved.

[0112] When the polyurethane elastic fiber of the present invention contains a tertiary amine compound, the tertiary amine compound used is not particularly limited so long as the compound has an amino group in the structure, but from the perspective of chlorine degradation resistance and yellowing of the polyurethane elastic fiber, among primary to tertiary amino groups, having only a tertiary amino group in the molecule is particularly preferable.

[0113] More specifically, examples of the contained tertiary amine compound include a linear high molecular compound having a number average molecular weight of 2,000 or more that is produced by a reaction of t-butyl diethanolamine and methylene-bis-(4-cyclohexyl isocyanate), polyethyleneimine, a high polymer compound having a branched structure containing a primary amino group, a secondary amino group, and a tertiary amino group in the molecular backbone, or the like.

[0114] When the number average molecular weight of the tertiary amine compound when the polyurethane elastic fiber of the present invention contains a tertiary amine compound is less than 2,000, water repellency processability deteriorates due to shedding as a result of friction with a guide or knitting needle during forming of the polyurethane elastic fiber or due to outflow during processing in a bath such as dyeing. Therefore, the number average molecular weight must be 2,000 or more. In view of solubility in the polyurethane spinning dope, a range of the number average molecular weight is preferably 2,000 to 10,000. More preferably, the range is 2,000 to 4,000.

[0115] In the polyurethane resin composition and polyurethane elastic fiber of the present invention, the content of a degradation product of the tertiary amine compound described above is preferably regulated to 1.0 mass% or less. When the content of the degradation product of the tertiary amine compound is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable wound thread form, combined durability, yellowing resistance may be obtained. A more preferable content of the degradation product of the tertiary amine compound is in the range of 1.0 mass% or less, and further preferably in the range of 0.5 mass% or less.

[0116] Furthermore, in the polyurethane resin composition and polyurethane elastic fiber of the present invention, it is preferable to contain a crosslinked structure regulator, in which case, such is preferably contained at 0.002 mass% or more and 2.0 mass% or less. A crosslinked structure regulator is an agent that is added after a polymerization terminator is added in polymerization of the polyurethane resin and the polymerization is completed. When the content of the crosslinked structure regulator is within this range, practically preferable properties of the polyurethane elastic fiber, particularly preferable breaking stretching strength, permanent strain rate, and yellowing resistance are ensured. A more preferable content of the crosslinked structure regulator in the range of 0.02 mass% or more and 1.5 mass% or less, and further preferably in the range of 0.2 mass% or more and 1.0 mass% or less.

[0117] Examples of the contained crosslinked structure regulator include monoamines and / or diamines. More specific examples of a monoamine include dimethylamine, diethylamine, cyclohexylamine, and the like, and examples of a diamine include ethylenediamine, 1,2- propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p- xylylenediamine, m-xylylenediamine, 1,3 -cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, and the like. It is particularly preferable to use a monoamine and diamine mixture.

[0118] Note that in terms of the molecular weight of the polyurethane resin included in the polyurethane resin composition after being made the polyurethane elastic fiber in the present invention, when a tertiary amine compound having a number average molecular weight in a range of 2,000 to 10,000 or an antioxidant having a molecular weight of 1,000 or more, which is preferably used, is mixed in, the number average molecular weight is preferably in a range of 10,000 or more and 50,000 or less. Note that the molecular weight is measured by GPC and converted using polystyrene. Note that the molecular weight of the polyurethane resin contained in the polyurethane resin composition after being made into the polyurethane elastic fiber may be abbreviated to "molecular weight as polyurethane elastic fiber." Note that the polyurethane resin or polyurethane elastic fiber obtained according to the present invention may be recycled and mixed in as part of the polyurethane raw materials so long as the scope of the present invention is not exceeded.

[0119] Next, a method for producing the polyurethane elastic fiber of the present invention will be described in detail.

[0120] In the present invention, it is preferable to first prepare a polyurethane solution. A method for producing the polyurethane solution and the polyurethane which is the solute in the solution may be either of melt polymerization method or a solution polymerization method, or may be any other method. However, a more preferred method is solution polymerization. In the case of a solution polymerization method, the generation of foreign matter such as gel and the like in the polyurethane is small, and therefore, spinning is easy, and it is easy to produce a polyurethane elastic fiber having low denier. Furthermore, in the case of solution polymerization, there is an advantage in that an operation to make a solution can be omitted.

[0121] The polyurethane elastic fiber of the present invention may be used in various applications. Specific examples include pantyhose, bras, slips, camisoles, bodysuits, underwear, girdles, tightening strings for socks and pants, swimwear, training wear, yoga wear, mountaineering wear, work clothes, fire-resistant suits, clothing such as men’s and women’s suits produced in combination with natural stable fibers, wet suits, leak-prevention tightening members for sanitary products such as disposable diapers, artificial skin, artificial blood vessels, artificial hearts, electrical insulation materials, wiping cloths, copier cleaners, gaskets, tightening members for safety clothing, tightening members for laboratory coats, tightening members for waterproof materials, tightening members for bandages and gloves, and the like. That is, the polyurethane elastic fiber may be suitably used in areas where elastic stretching force is required.

[0122] [Examples]

[0123] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0124] In the examples, each item was measured by the following method. Note that in the cases where the number of evaluations n is not specifically stated, the evaluation was performed with n = 3.

[0125] <DSC Measurement

[0126] Measurement was carried out using a DSC-2500 manufactured by TA Instruments Japan, Ltd. in MDSC mode. Approximately 5 mg of a cut sample yam was placed in an aluminum pan, covered with a cover and crimped to prepare a sample. After the sample and a reference were set at predetermined positions in a cell, measurement was carried out under a nitrogen gas flow at a flow rate of 40 Nml / min. These were cooled from room temperature to -90°C and held there for 5 minutes, and then heated to 300°C at an average heating rate (average scanning rate) of 2°C / min. An exothermic peak temperature and amount of heat generated due to crystallization, and an endothermic peak temperature and amount of heat absorbed due to melting were measured and were respectively taken as the crystallization point and melting point (unit: °C) and enthalpy (unit: J / g), respectively.

[0127] <Breaking Elongation, Breaking Strength, Permanent Strain Rate, Stress Relaxation Rate, etc.>

[0128] The breaking elongation, breaking strength, permanent strain rate, stress relaxation rate, and the like were measured by subjecting the polyurethane elastic fiber to tensile tests using an Instron model 5564 tensile tester.

[0129] A sample having a test length of 5 cm (LI) was subjected to 300% elongation five times at a tensile rate of 50 cm / minute. At this time, the stress at 200% elongation was defined as (G+200), and the stress at 300% elongation was defined as (Gl).

[0130] Next, the sample length was maintained for 30 seconds at 300% elongation. The stress after being maintained for 30 seconds was defined as (G2).

[0131] Next, the sample elongation was recovered, the stress at 200% elongation recovery was defined as (G-200), and the length of the sample when the stress became 0 was defined as (L2).

[0132] This operation of 300% elongation, maintenance, and recovery was repeated, and at a 6th elongation, the sample was elongated until severing. The stress at break was defined as (G3), and the sample length at break was defined as (L3). Hereinafter, the above characteristics are calculated by the following formulas.

[0133] • Breaking strength (cN) = (G3)

[0134] 20 or more: S, 17 or more and less than 20: A, 14 or more and less than 17: B, less than 14: C

[0135] • Breaking elongation (%) = 100 x ((L3)-(L1)) / (L1)

[0136] 480 or more: S, 460 or more and less than 480: A, 430 or more and less than 460: B, less than 430: C

[0137] • Stress at 200% elongation (cN) = (G+200)

[0138] 1.2 or more and less than 1.4: S, 1.4 or more and less than 1.5: A, 1.5 or more and less than 1.6: B, over 1.6: C

[0139] • Stress at 200% elongation recovery = (G-200),

[0140] 1.2 or more: S, 1.0 or more and less than 1.2: A, 0.8 or more and less than 1.0: B, less than 0.8: C

[0141] • Permanent strain rate (%) = 100 x ((L2)-(L1)) / (L1)

[0142] Less than 20: S, 20 or more and less than 22: A, 22 or more and less than 24: B, 24 or more: C

[0143] • Stress relaxation rate (%) = 100 x ((G1)-(G2)) / (G1)

[0144] Less than 25: S, 25 or more and less than 28: A, 28 or more and less than 31: B, 31 or more: C.

[0145] <Heat Resistance>

[0146] A two-way half tricot having a machine well number of 9 / inch and a machine course number of 18 / inch composed of 85 mass% of nylon filament (24 dtex, 7 filaments) and 15 mass% of polyurethane elastic fiber (44 dtex) was produced by a normal forming method to make a raw knitted fabric.

[0147] The obtained raw knitted fabric was preset under conditions of 3% elongation for 60 seconds at 170°C, and 0.1 mL of an Agent 1 was applied, followed by an application of 0.1 mL of an Agent 2 (at substantially the same time and within 1 minute). Next, this was submitted to dry heat treatment (after dry heat treatment for 60 seconds at 175°C, the fabric was extracted once, and after radiating to room temperature, dry heat treatment was then performed for 60 seconds at 180°C), then, the fabric was subjected to a bending tester with a maximum elongation of 20% alternately in both the vertical and horizontal directions, twice / second. Note that a mineral oil-based spinning oil for nylon containing 1 mass% oleic acid was used as Agent 1. Furthermore, an aqueous solution of copper acetate (copper concentration of 100 ppm) was used as Agent 2. The raw knit fabric to which Agents 1 and 2 had been applied in this manner was a model that reproduced the nylonbased stretch raw knit fabric at a stage before dyeing, which has trace amounts of machine oil (containing metals) and spinning oil for nylon adhering thereto during knitting. The amount of Agent 1 adhered to 0.9 g of raw knit fabric was 3.0 mg, and the amount of Agent 2 adhered thereto was 3.0 mg.

[0148] The obtained stretch fabric was dyed using a conventional method.

[0149] A degree of damage to the polyurethane tissue in the obtained dyed stretch fabric was observed visually with the naked eye or under magnification, and a determination was made using the following criteria. Note that the determination was performed by five people and that the mode (the determination appearing most frequently) was used. In addition, when the judgements were split between 2, 2, and 1 person, the judgement was given as "B."

[0150] S: No damage and the knitting structure is uniform.

[0151] A: No damage.

[0152] B: Sagging and depressions are observed in the fabric, and when observed under magnification, the polyurethane elastic fiber is brittle.

[0153] C: There are holes in the fabric.

[0154] <Light Resistance, Yellowing>

[0155] Characteristics after the following exposure treatments (A) and (B) were determined according to the following.

[0156] (A) Ultraviolet (UV) exposure treatment

[0157] Using a carbon arc type weather meter manufactured by Suga Test Instruments Co., Ltd., the sample was subjected to exposure treatment at a temperature of 63 °C and a humidity of 60% RH for 25 hours. (B) Nitrogen oxide (NOx) exposure treatment

[0158] Using a sealed container (Scott tester) with a rotating sample stand, the sample was subjected to exposure treatment using 10 ppm NO2 gas at a temperature of 40°C and a relative humidity of 60% RH for 20 hours.

[0159] • Light Resistance

[0160] The following exposure treatment (A) was performed while the sample yarn was elongated to 100%, and the subsequent breaking strength retention rate was found, and the determinations are as follows.

[0161] 80% or more: S, 60% or more and less than 80%: A, 40% or more and less than 60%: B, less than 40%: C

[0162] • Yellowing

[0163] Yellowing was evaluated using the degree of yellowing (hereinafter abbreviated as Ab) following exposure treatments (A) and (B) on the sample.

[0164] 3 or less: S, 3 or more and less than 6: A, 6 or more and less than 10: B, 10 or more: C

[0165] Note that during each exposure treatment, the degree of yellowing Ab was calculated as follows.

[0166] Ab = b value after exposure treatment - b value before exposure treatment

[0167] The measurement sample form and measurement of yellowing were as follows.

[0168] The sample yarn was wound onto a 5 x 5 cm sample plate at minimal load and in close contact to the extent that the color of the sample plate did not affect the sample, and this was made to be the sample.

[0169] The front surface of the sample and a common-use standard white surface (4.3.4 of JIS Z 8722) were tightly covered with a homogeneous, flat, transparent glass plate of approximately 1 mm. The b value was measured in accordance with JIS L 1013, Method C (Hunter's method) using a Hunter type color difference meter and calculated based on the following formula. The number of measurements was 5, and the average of the measurements was used. b = 7.0(Y-0.847Z) / Y1 / 2 (However, X, Y, and Z were calculated according to JIS Z 8701).

[0170] <Number Average Molecular Weight>

[0171] Number average molecular weight measurement by GPC was carried out under the following conditions.

[0172] Column: Two SHODEX KF-806M columns manufactured by Showa Denko K.K.

[0173] Solvent: N,N-dimethylacetamide 1 mL / min

[0174] Temperature: 40°C

[0175] Detector: Differential refractometer (RI detector).

[0176] <Viscosity>

[0177] 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. Note that the viscosity tube used had an inner diameter of 31.4 (± 0.2) mm.

[0178] <Spinning Solution Stability >

[0179] After the spinning solution was left to stand for 2 hours at 40°C (the temperature of a constant temperature bath of a falling ball viscometer) to stabilize, 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 (after another 24 hours have passed) were respectively measured by the method described in <Viscosity> above.

[0180] Then, a viscosity ratio (initial viscosity / viscosity after 24 hours) was calculated from the initial viscosity and viscosity after 24 hours.

[0181] < Spinning Continuity >

[0182] A 44 dtex, 4 filament yarn (fiber) was continuously spun for 96 hours by dry spinning, and the number of yarn breakages was counted and the following evaluation was made.

[0183] 0 thread breaks = Very favorable S

[0184] 1 to 2 thread breaks = Favorable A

[0185] 3 to 4 thread breaks = Acceptable B

[0186] 5 thread breaks = Defective C <Bio-based ContenO

[0187] The bio-based content (mass%) was measured using ISO 16620-2, which is a radiocarbon

[0188] (carbon- 14) concentration measurement identification method.

[0189] <Raw Materials Used in the Examples and Comparative Examples>

[0190] (Polymer Diol Having a Structure of Formula (1))

[0191] • PO3G1 : Number average molecular weight 2,000

[0192] Using 1,3 -propanediol at a purity of 99.8 mass% as a raw material, polymerization was carried out by the well-known method described in JP 2003-517082 A (Translation of PCT Application). The melting point was measured by DSC and found to be 15°C.

[0193] (Polymer Diol Having a Structure of Formula (2))

[0194] • PO4G1 : Number average molecular weight 1,800

[0195] A commercially available product Terathane(R) #1800 manufactured by Invista was used.

[0196] (Polymer Diol Having a Structure of Formula (3))

[0197] • PO4G / PO3G-1

[0198] Synthesized by the following procedure.

[0199] Using a mixture of THF, 1,3 -propanediol, 1,3-propanediol dimer and 1,3 -propanediol trimer as a raw material, PO4G / PO3G-1 having a number average molecular weight of 1,900 was polymerized by the known method described in JP 2008-503486 A (Translation of PCT Application). The obtained PO4G / PO3G-1 had a melting point of -24°C as measured by DSC.

[0200] • PO4G / PO3G-2 to 4

[0201] The following PO4G / PO3G-2 to 4 were synthesized using the same method described in the experimental section of the 51st Petroleum and Petrochemical Symposium Abstracts 1F05 (November 2021), under conditions of changing the presence and type of a solid acid catalyst.

[0202] • PO4G / PO3G-2

[0203] According to the above-mentioned literature, a mixture of THF and 1,3-propanediol was charged into a round-bottom flask without adding a solid acid catalyst, and the flask was placed under a nitrogen gas atmosphere, then sealed, and stirred at 120°C for 40 hours in a sealed state while stirring at 800 rpm.

[0204] The c / (c+d) in formula (3) of the obtained polymer diol having a structure of PO4G / PO3G-2 was determined using a gas chromatograph equipped with a hydrogen flame ionization detector, and was found to be 2.4.

[0205] • PO4G / PO3G-3

[0206] According to the document described above, a mixture of THF, 1,3 -propanediol, and amorphous silica alumina as a solid acid catalyst was charged into a round-bottomed flask, sealed under a nitrogen gas atmosphere, and stirred for 40 hours at 120°C in a sealed state while stirring at 800 rpm.

[0207] The c / (c+d) in formula (3) of the obtained polymer diol having a structure of PO4G / PO3G-3 was determined using a gas chromatograph equipped with a hydrogen flame ionization detector, and was found to be 12.

[0208] • PO4G / PO3G-4

[0209] According to the document described above, a mixture of THF, 1,3 -propanediol, and MFI zeolite (SiO2 / A12O3 mol ratio = 22) manufactured by Tosoh Corporation as a solid acid catalyst was charged into a round-bottomed flask, sealed under a nitrogen gas atmosphere, and stirred for 40 hours at 120°C in a sealed state while stirring at 800 rpm.

[0210] The c / (c+d) in formula (3) of the obtained polymer diol having a structure of PO4G / PO3G-4 was determined using a gas chromatograph equipped with a hydrogen flame ionization detector, and was found to be 31.

[0211] (Polymer Diol Having a Structure Other than Formulas (1) to (3))

[0212] • Modified PO4G: Polytetramethylene ether diol having an alkyl group on a side chain

[0213] Synthesized by the following procedure.

[0214] 87.5 mol of dehydrated THF and 4.0 mol of dehydrated 3-methyl-tetrahydrofuran were placed in a reactor equipped with a stirrer, a polymerization reaction was performed for 8 hours under a nitrogen seal at a temperature of 10°C in the presence of a catalyst (a mixture of 70 mass% perchloric acid and 30 mass% acetic anhydride), and a copolymerized tetramethylene ether diol having a number average molecular weight of 3,500 (including 8.0% by mole of structural unit derived from 3 -methyl- tetrahydrofuran) was obtained by a copolymerization method of neutralization using an aqueous sodium hydroxide solution in the reaction termination solution.

[0215] [Comparative Example 1] (corresponding to conventional art)

[0216] 4,4'-MDI and 2,4'-MDI (mole ratio 98:2) was placed in a container so as to constitute 1.60 mol with respect to 1 mole of PO4G1 and reacted at 90°C, and the obtained reaction product was added to N,N-dimethylacetamide (DMAc) sufficiently stirred, and dissolved to obtain a solution. Next, a DMAc solution containing ethylenediamine (EDA) as a chain extender was added to the solution in which the reaction product was dissolved, and a DMAc solution containing diethylamine as a terminal sequestering agent was further added to prepare a polyurethane urea solution (PUUX1) having a polymer solid content of 35 mass%. The obtained solution had a viscosity of approximately 2,500 poise at 40°C. The polymer had an intrinsic viscosity of 0.95 when measured at 25°C at a solution concentration of 0.5 g / 100 mL in DMAc.

[0217] Next, a one-to-one (mass ratio) mixture of a polyurethane ("Methachlor" ® 2462 manufactured by DuPont) produced by reacting t-butyl diethanolamine and methylene-bis-(4-cyclohexyl isocyanate) and a condensation polymer of p-cresol and divinylbenzene ("Methachlor" ® 2390 manufactured by DuPont) was used as an antioxidant, and a DMAc solution (35 mass%) of this mixture was prepared to produce an additive solution (B).

[0218] The foregoing 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, and were made to be the spinning solution (D).

[0219] The initial viscosity of the spinning solution (D) was 2,000 P (poise) (= 190,000 mPa- s), and the viscosity after 24 hours was 2,050 P, and the viscosity ratio thereof was calculated to be 1.025.

[0220] Using the spinning solution (D) obtained in this manner, dry spinning was carried out at a dry nitrogen temperature of 300°C or higher so that DMAc and floating ethylene diamine in the spinning solution were 1 / 100 or less of the content of the spinning solution. At this time, the 44 dtex / 4 fil multifilament polyurethane elastic fiber was spun with the speed ratio of the godet roller and the winder set to 1 : 1.20, the treatment agent (oil agent) described below was supplied to the roller by the oiling roller before winding, and this was wound using a surface drive winder via a traverse guide providing a winding width of 38 mm to a cylindrical paper tube having a length of 58 mm at a winding speed of 600 m / min, to obtain a dry spun polyurethane elastic fiber as a 500 g wound body. The obtained polyurethane elastic fiber was a spliced yarn made by provisionally twisting and splicing four filaments together. The rotational speed of the oiling roller was adjusted so that the amount of treatment agent applied was a predetermined amount relative to the yam. Furthermore, the amount of treatment agent applied was measured using n-hexane as an extraction solvent in accordance with JIS-L1073 (synthetic fiber filament yarn testing method). The composition of the treatment agent used here is a mixture of 80 parts by mass of polydimethylsiloxane having a viscosity of 1 x 10'5m2 / s at 25°C, 15 parts by mass of mineral oil having a viscosity of 1.2 x 10'5m2 / s at 25°C, and 5 parts by mass of magnesium distearate having an average particle diameter of 0.5 pm.

[0221] Note that the number average molecular weight of the polymer constituting the fiber (or thread) was 22,000.

[0222] The results, including various evaluations, are shown in the table.

[0223] [Comparative Example 2] (corresponding to the conventional art) Using PO3G1 instead of PO4G1 in Comparative Example 1, a 44 dtex / 4 fil multifilament polyurethane elastic fiber was obtained under the same polymerization conditions, additive blending, and spinning conditions as in Comparative Example 1.

[0224] The obtained polyurethane solution had a viscosity of approximately 2,400 poise at 40°C. The polymer had an intrinsic viscosity of 1.05 when measured at 25°C at a solution concentration of 0.5 g / 100 mL in DMAc.

[0225] The initial viscosity of the obtained spinning dope was 2,100 P (poise) (= 210,000 mPa- s), and the viscosity after 24 hours was 2,100 P, and the viscosity ratio thereof was calculated to be 1.00.

[0226] The number average molecular weight of the polymer constituting the obtained fiber (or thread) was 24,000.

[0227] The results, including various evaluations, are shown in the table.

[0228] [Comparative Example 3] (corresponding to conventional art)

[0229] 4,4'-MDI was placed in a container so as to constitute 1.97 mol with respect to 1 mole of modified PO4G (polymerized tetramethylene ether diol, not corresponding to a polymer diol having a structure of formula (1)) and reacted at 90°C, and the obtained reaction product was sufficiently mixed and dissolved in N,N-dimethylacetamide (DMAc) to obtain a solution. Next, a DMAc solution containing 60% by mole of ethylenediamine (EDA) and 40% by mole of 1,2- propanediamine (1,2-PDA) as a chain extender was added to a solution in which the reaction product was dissolved, and a DMAc solution containing diethylamine as a terminal sequestering agent was further added to prepare a polyurethane urea solution having a polymer solid content of 35 mass%.

[0230] Using the same additive formulation and spinning conditions as in Comparative Example 1, a 44 dtex / 4 fil multifilament polyurethane elastic fiber was obtained.

[0231] The obtained polyurethane solution had a viscosity of approximately 2,200 poise at 40°C. The polymer had an intrinsic viscosity of 0.98 when measured at 25°C at a solution concentration of 0.5 g / 100 mL in DMAc.

[0232] The initial viscosity of the obtained spinning dope was 2,050 P (poise) (= 205,000 mPa- s), and the viscosity after 24 hours was 1,950 P, and the viscosity ratio thereof was calculated to be 0.95.

[0233] The number average molecular weight of the polymer constituting the obtained polyurethane elastic fiber was 20,000.

[0234] The results, including various evaluations, are shown in the table.

[0235] [Examples 1 to 3]

[0236] A polyurethane urea fiber of 44 dtex was produced by the same method as in Comparative Example 1, except that PO4G1 and PO3G1 were used as the polymer diol components in the proportions shown in Table 1 instead of the polymer diol.

[0237] The glass transition point (Tg) of this polyurethane urea fiber was -71 °C. Note that the effective terminal amine concentration constituting the polyurethane urea fiber was 20 meq / kg.

[0238] [Examples 4 to 6]

[0239] As shown in Table 1, based on Examples 1 to 3, a 44 dtex polyurethane urea fiber was produced by the same method as Example 1, except that when synthesizing the polyurethane resin, a copolymer of PO4G1 and PO3G1 (PO4G / PO3G-1) was mixed at 1 mass% in the polymer diol mixture.

[0240] [Examples 7 to 9]

[0241] As shown in Table 1, based on Examples 1 to 3, a 44 dtex polyurethane urea fiber was produced by the same method as Example 1, except that when synthesizing the polyurethane resin, PO4G / PO3G-1 was mixed at 10 mass% in the polymer diol mixture.

[0242] As can be seen from Table 1, the DSC measurement results show that by using a mixed polymer diol of PO4G1 and PO3G1, the soft segment melting point is lower than when the polymer diol is constituted of only PO4G1 or only PO3G1, and the endothermic enthalpy amount is also smaller. This is believed to be due to the suppression of crystallization. In fact, it is seen that the mechanical properties such as stress during 200% elongation recovery are improved by using a mixed polymer diol of PO4G1 and PO3G1 compared to the use of PO4G1 alone or PO3G1 alone. That is, as a result, the stress during elongation and the stress during elongation recovery became favorable.

[0243] Also, by using a mixed polymer diol of PO4G1 and PO3G1, the hard segment melting point measured by DSC has a tendency to be higher than when the polymer diol is constituted of only PO4G1 or only PO3G1, and the endothermic enthalpy amount is also larger. That is, separation of the soft segment and the hard segment becomes clear, and the hard segment crystals become stronger. As a result, the breaking strength and breaking elongation increased.

[0244] [Examples 11 and 12]

[0245] A polyurethane urea fiber of 44 dtex was produced by the same method as in Comparative Example 1, except that PO4G1 and PO3G1 were used as the polymer diol components in the proportions shown in Table 2 instead of the polymer diol.

[0246] [Examples 13 to 16] As shown in Table 2, based on Examples 1 to 3, a 44 dtex polyurethane urea fiber was produced by the same method as Example 1, except that when synthesizing the polyurethane resin, PO4G / PO3G-2 or PO4G / PO3G-3 or PO4G / PO3G-4 was mixed at 1 mass% in the polymer diol mixture. [Examples 17 to 19]

[0247] As shown in Table 2, based on Examples 1 to 3, a 44 dtex polyurethane urea fiber was produced by the same method as Example 1, except that when synthesizing the polyurethane resin, PO4G / PO3G-2 or PO4G / PO3G-3 or PO4G / PO3G-4 was mixed at 10 mass% in the polymer diol mixture.

[0248] [Table 1]

[0249] [Table 2]

Claims

CLAIMS1. A polyurethane resin composition using as a main component a polyurethane resin using a polymer diol and a diisocyanate as starting materials, wherein the polyurethane resin comprises, as the starting material polymer diol, a 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 whose structure of a portion other than a hydrogen at both ends is represented by the following formula (2) at a total of 50 mass% or more of the entire polymer diol, and mass ratios r(l) and r(2) of structural parts respectively corresponding to the following formulas (1) and (2) to the total structural parts derived from polymer diols satisfy the following relational formula (A).[Math. 1]0.1 ^r(l) / (r(l)+r(2)) ^0.9 (A)[Chem. 1]*-O(CH2CH2CH2-O)a-* (1)[Chem. 2]*-O(CH2CH2CH2CH2-O)b-* (2)In formulas (1) and (2), for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

2. The polyurethane resin composition according to claim 1, wherein further comprised as the starting material polymer diol is a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the following formula (3), and a mass ratio r(3) of a structural part corresponding to the following formula (3) to the total structural parts derived from polymer diols and the mass ratios r(l) and r(2) satisfy the following relational formula (B).[Math. 2]0.001 ^r(3) / (r(l)+r(2)+r(3)) 0.3 (B)[Chem. 3]*- O(CH2CH2CH2-O)c-(CH2CH2CH2CH2-O)d-* (3)In formula (3), linkage of unit structures having a number of repeating c and d may be in block or random form, and for bonds marked with *, these structural parts represent bonds with a hydrogen atom in the polymer diol, and if these structural moieties are present at a terminal of the polyurethane resin, they represent bonds with a hydrogen atom, and if present anywhere other than a terminal of the polyurethane resin, they represent a bond between O and C=O in the urethane bond.

3. The polyurethane resin composition according to claim 1, wherein the mass ratios r(l) and r(2) satisfy the following relational formula (A').[Math. 3]0.1 ^r(l) / (r(l)+r(2)) ^0.6 (A’)4. The polyurethane resin composition according to claim 2, wherein the mass ratios r(l), r(2), and r(3) satisfy the following relational formula (B’).[Math. 4]0.005 ^r(3) / (r(l)+r(2)+r(3))^0.15 (B’)5. The polyurethane resin composition according to claim 1, wherein, when taking polymer diols whose structure of a portion other than a hydrogen at both ends is represented by the following formulas (1) to (3) as the whole, a number average molecular weight is 1,000 or more and 30,000 or less, and a ratio of a number average molecular weight of a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the formula (2) to a number average molecular weight of a polymer diol whose structure of a portion other than a hydrogen at both ends is represented by the formula (1) is 1.00 to 1.16.

6. The polyurethane resin composition according to claim 1, wherein the bio-based content bycarbon isotope ratio measurement established in ISO 16620-2 is 3% or more in a carbon mass ratio.

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