[Title of the Invention] Polyurethane Urea Elastic Fiber and Production Method Therefor

[Technical Field]

The present invention relates to a polyurethane urea elastic fiber and a production method therefor.

[Background Art]

Polyurethane elastic fibers are roughly classified as polyurethane urea elastic fibers primarily using a diol as a chain extender and polyurethane urea elastic fibers primarily using diamine as a chain extender.

The former is characterized by high strength and high elasticity. Patent Document 1 shows an example of a polyurethane urea elastic fiber whose physical properties do not change much over time.

The latter has high elasticity, but is not as strong as the former and has physical properties that tend to change over time. As a result, there are problems with inventory management and fiber processing condition management, and it can be difficult to obtain a fabric with stable physical properties and qualities. In other words, there are no polyurethane urea elastic fibers that have high strength and whose physical properties are retained and do not change much over time.

In order to address the problem of unstable physical properties that change over time, an attempt has been made to obtain a polyurethane elastic fiber that leads to fabrics that have good fit and feel, that are easy to take off, and that absorb and wick moisture (Patent Document 2). However, in the method described in Patent Document 2, the amount of polyacrylic acid and/or polyacrylamide added to the spinning solution has to be increased in order to improve these effects.

Patent Document 3 describes an example of a polyurethane urea elastic fiber that uses a specific compound as a stopping agent during production of the polyurethane urea, which appears to hold down the viscosity of the polyurethane urea solution. Patent Document 4 discloses a polyurethane elastic fiber with excellent strength, elasticity, resilience, and light resistance that is obtained by adding a benzophenone-based ultraviolet absorber containing one or more sulfonic acid groups per molecule to the polyurethane elastic fiber.

[Prior Art Documents]

[Patent Documents]

[Patent Document 1] JP Hll-081045 A

[Patent Document 2] JP 2002-249930 A

[Patent Document 3] JP 2003-155624 A

[Patent Document 4] JP 2011-144491 A

[Summary of the Invention] [Problem to Be Solved by the Invention]

No polyurethane urea elastic fibers whose physical properties do not change much over time and which maintain the initial mechanical properties of conventional polyurethane urea elastic fibers, or methods for obtaining these fibers, have been disclosed.

An object of the present invention is to provide a polyurethane urea elastic fiber whose physical properties do not change much over time and which retains its initial mechanical properties, and a method for obtaining this fiber by modifying the molecular chain and ends of the polyurethane urea polymer. Another object of the present invention is to provide a polyurethane urea elastic fiber whose use can improve inventory management and fiber processing condition management, and which can be used to obtain a fabric with stable physical properties and qualities, and to provide a method for producing this fiber.

[Means for Solving the Problem]

In order to solve this problem, the present invention uses the following means.

(1) A polyurethane urea elastic fiber comprising : polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end; and polyurethane urea polymer B using a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid as starting materials, and containing an amide bond, wherein the polyurethane urea elastic fiber contains primary or secondary amino end groups in the range of 0.1 meq or more and 20 meq or less per kilogram of polyurethane urea elastic fiber.

(2) A polyurethane urea elastic fiber according to (1), wherein the polyurethane urea elastic fiber has an amine bond total in the range of 0.1 meq or more and 10 meq or less per kilogram of polyurethane urea elastic fiber.

(3) A polyurethane urea elastic fiber according to (1) or (2), wherein the molecular weight of the structural portion derived from the organic carboxylic acid is 100 or more and 300 or less.

(4) A method for producing a polyurethane urea elastic fiber, the method comprising : dry spinning a spinning solution containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having an amino group on at least one end; and polyurethane urea polymer B using a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid as starting materials, and containing an amide bond, wherein the amount of primary or secondary amino groups in polyurethane urea polymer A and polyurethane urea polymer B contained in the spinning solution is in the range of 0.1 meq or more and 25 meq or less per kilogram.

(5) A method for producing a polyurethane urea elastic fiber according to (4), the method comprising : preparing solution a containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end; adding an organic carboxylic acid-based compound to solution a to react with some of the polyurethane urea polymer A, produce polyurethane urea polymer B having a molecular chain containing an amide bond, and prepare a spinning solution containing polyurethane urea polymer A and polyurethane urea polymer B; and dry spinning the spinning solution.

(6) A method for producing a polyurethane urea elastic fiber according to (4), the method comprising : preparing solution a containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end; separating some of solution a and adding an organic carboxylic acid compound to react with polyurethane urea polymer A, produce polyurethane urea polymer B having a molecular chain containing an amide bond, and prepare solution b; mixing solution a and solution b together to prepare a spinning solution containing polyurethane urea polymer A and polyurethane urea polymer B; and dry spinning the spinning solution.

(7) A method for producing a polyurethane urea elastic fiber according to any of (4) to (6), wherein a cyclic acid anhydride having a molecular weight of 100 or more and 300 or less is used as the organic carboxylic acid or the organic carboxylic acid-based compound.

[Effect of the Invention]

Because the polyurethane urea elastic fibers of the present invention have high elasticity and a low residual strain rate, clothes using these elastic fibers have a good fit and feel, and are easy to take off. Because these elastic fibers also have stable mechanical properties over time, they are easy to process in the covering, knitting, and weaving process, whether used alone or in combination with other types of fibers for higher-order processing.

[Mode for Carrying Out the Invention]

The following is a detailed description of the present invention.

First, the polyurethane ureas used in the present invention will be described. In the following description, the polyurethane urea polymer having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end is referred to as "polyurethane urea polymer A," and a polyurethane urea polymer having a molecular chain using a polymer diol, a di isocyanate, an organic amine, and an organic carboxylic acid as starting materials, and containing an amide bond in the molecular chains, is referred to as "polyurethane urea polymer B."

Polyurethane urea polymer B can be obtained, for example, by reacting at least one end of polyurethane urea polymer A with an organic carboxylic acid to form an amide bond in the molecular chain, but the production method is not limited to this example. Polyurethane urea polymer B preferably has an alkyl group or a carboxyl group with a structure derived from an organic carboxylic acid on at least one end, and more preferably has a carboxyl group with a structure derived from an organic carboxylic acid at both ends.

Polyurethane urea polymer A and polyurethane urea polymer B are sometimes referred to collectively as the "polyurethane urea polymers," and a polyurethane urea polymer mixture containing polyurethane urea polymer A and polyurethane urea polymer B is sometimes referred to as the "polyurethane urea polymer mixture." There are no particular restrictions on the method used to obtain a polyurethane urea polymer mixture containing polyurethane urea polymer A and polyurethane urea polymer B, which may be any of the methods described in greater detail below. For example, polyurethane urea polymer A and polyurethane urea polymer B may be prepared separately and then mixed together to obtain a polyurethane urea polymer mixture. Alternatively, an excess amount of polyurethane urea polymer A can be reacted with an organic carboxylic acid to adjust the amount of polyurethane urea polymer B produced and leave behind enough polyurethane urea polymer A to obtain a polyurethane urea polymer mixture.

Any polyurethane urea polymer A can be used in the present invention as long as the polyurethane urea polymer has a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and has a primary or secondary amino group on at least one end. Similarly, any polyurethane urea polymer B can be used in the present invention as long as long as the polyurethane urea polymer has a molecular chain using a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid as starting materials, and contains an amide bond.

Here, a polymer diol, diisocyanate, and organic amine used as starting materials or a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid used as starting materials means the resulting polyurethane polymer has a structure derived from each component. In other words, in the present specification, this identifies the structure of a polyurethane urea polymer obtained from a polymer diol, a diisocyanate, and an organic amine used as starting materials or a polyurethane urea polymer obtained from a polymer diol, a diisocyanate, and an organic amine used as starting materials. An equivalent structure may be obtained using different raw materials, and the raw materials themselves are not specified. Similarly, there are no particular restrictions on the synthesis method even when a polymer is synthesized using the same raw materials. For example, it may be a polyurethane urea polymer composed of a polymer diol, a diisocyanate, and a low molecular weight diamine, or a polyurethane urea polymer using a polymer diol, a diisocyanate, and a compound having a hydroxyl group and an amino group in the molecule as a chain extender. Two or more types of polyurethane urea polymers using different starting materials may be mixed together at any proportion. Polyfunctional glycols and isocyanates that are trifunctional or higher are preferably used as long as they do not impair the effects of the present invention.

Structural units typically used to compose a polyurethane urea of the present invention will now be described.

A polyether diol, a polyester diol, or a polycarbonate diol are preferred as the polymer diol used as a structural unit composing the polyurethane. A polyether diol is especially preferred from the standpoint of imparting flexibility and elasticity to the polyurethane urea fiber.

Preferred examples of polyether diols include polyethylene oxide, polyethylene glycol, polyethylene glycol derivatives, polypropylene glycol, polytetramethylene ether glycol (PTMG), modified PTMG (3M-PTMG) that is a copolymer with tetra hydrofuran (THF) and 3- methyltetra hydrofuran, modified PTMG that is a copolymer with THF and 2,3-dimethyl THF, the polyol with side chains on both sides that is disclosed in JP 2615131 B2, and a random copolymer in which THF and ethylene oxide and/or propylene oxide are irregularly arranged. One or more of these polyether diols may be mixed together or copolymerized and then used.

From the standpoint of obtaining wear resistance and light resistance, preferred examples include butylene adipate, polycaprolactone diol, polyester diols such as the polyester polyol with a side chain disclosed in JP S61-026612 A, and the polycarbonate diol disclosed in JP H02-289516 A. These polymer diols may be used alone, or two or more may be mixed together or copolymerized and then used.

From the standpoint of obtaining elasticity, strength, and heat resistance when made into a fiber, the number average molecular weight of the polymer diol is preferably 1,000 or more and 8,000 or less, and more preferably 1,800 or more and 6,000 or less. When a polyol with a molecular weight in this range is used, elastic fibers having excellent elasticity, strength, elastic resilience, and heat resistance can be readily obtained. The molecular weight is measured by GPC and converted in terms of polystyrene.

Aromatic diisocyanates are especially suitable for synthesizing polyurethanes with high heat resistance and strength. Examples include diphenylmethane diisocyanate (MDI), tolylene diisocyanate, 1,4-diisocyanate benzene, xylylene diisocyanate, and 2,6-naphthalene diisocyanate. Preferred examples of alicyclic diisocyanates include methylenebis (cyclohexyl isocyanate) (H12MDI), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4-diisocyanate, hexa hydroxylylene diisocyanate, hexahydrotolylene diisocyanate, and octahydro-l,5-naphthalenediisocyanate. Aliphatic diisocyanates are especially effective for suppressing the yellowing of polyurethane urea elastic fibers. These diisocyanates may be used alone or in combinations of two or more.

An organic amine is used as a chain extender when synthesizing a polyurethane urea polymer from a polymer diol and a diisocyanate as described above. The organic amine is preferably at least one type of low molecular weight amine with two or more amino groups. When the chain extender is at the end of the molecule, a primary amino end group is formed. Especially preferred is a low molecular weight diamine with two amino groups. Those with both a hydroxyl group and an amino group in the molecule such as ethanolamine may be used.

Preferred examples of low molecular weight diamines include ethylenediamine, 1,2- propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p-xylenediamine, m-xylylenediamine, p,p'-methylenedianiline, 1,3- cyclohexyldiamine, hexahydromethphenylenediamine, 2-methylpentamethylenediamine, and bis (4-aminophenyl) phosphine oxide. These may be used alone or in combinations of two or more. Ethylenediamine is especially preferred. Ethylenediamine can be used to readily obtain a fiber having excellent elasticity, elasticity recovery, and heat resistance. A triamine compound that can form a crosslinked structure, such as diethylenetriamine, may be added to these chain extenders as long as the effects of the present invention are not lost.

The polyurethane urea polymer may also have a structure at the end in which one or more of the following compounds has been introduced as end capping agents. Preferred examples of compounds used as end capping agents to introduce end structures in these cases include dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, diamylamine, and cyclohexylamine. The end structure introduced by the end capping agent is a secondary or tertiary amino group.

Polyurethane urea polymer A used in the present invention is a polyurethane urea polymer having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end.

A structure with a primary amino group at the end is formed when a chain extender becomes the end, and a structure with a secondary amino group at the end is formed by an end capping agent as described above. By adjusting these, a polyurethane urea polymer with a primary or secondary amino group on at least one end can be obtained.

From the standpoint of obtaining fibers with high durability and strength, the molecular weight of a polyurethane urea polymer used in the present invention is preferably in the range of 30,000 or more and 150,000 or less in terms of the number average molecular weight. The molecular weight is measured by GPC in terms of polystyrene.

A polyurethane urea elastic fiber of the present invention comprises a polyurethane urea polymer A described above and a polyurethane urea polymer B having an amide bond in the molecular chain and has primary or secondary amino end groups in the range of 0.1 meq or more and 20 meq or less per kilogram of polyurethane urea elastic fiber. Because the polyurethane urea elastic fiber contains a polyurethane urea polymer B having an amide bond in the molecular chain and the polyurethane urea polymers (polyurethane urea polymer A and some of polyurethane urea polymer B) have primary or secondary amino end groups in the range of 0.1 meq or more and 20 meq or less per kilogram of polyurethane urea elastic fiber, a polyurethane urea elastic fiber is obtained that has both excellent fiber property stability over time and spinning stability without losing the stretching performance inherent to polyurethane urea elastic fibers.

Polyurethane urea polymer B is preferably obtained by reacting at least one of the primary or secondary amino groups present at the end of the molecular chain of the polyurethane urea polymer A with an organic carboxylic acid.

The organic carboxylic acid used as a starting material in the present invention conceptually encompasses organic compounds with a carboxyl group in a molecule that are able to form a urethane bond by reacting with an isocyanate compound. Therefore, what is specifically used as a raw material in the method for producing a polyurethane urea elastic fiber of the present invention can be an organic carboxylic acid or an organic carboxylic anhydride as long as it is a compound that can impart a structure derived from such an organic carboxylic acid. In other words, the term "organic carboxylic acid compound" includes any compound that can impart a structure derived from an organic carboxylic acid in the method for producing a polyurethane urea elastic fiber of the present invention.

From the standpoint of stereoselectivity in a reaction with a polyurethane urea polymer in which both ends of the molecular chain are primary or secondary amino groups and optimization of the molecular chain steric hindrance of the resulting polyurethane urea polymer, the molecular weight of an organic carboxylic acid used as a starting material is preferably 100 or more and 300 or less. The molecular weight of an organic carboxylic acid compound used in the method for producing a polyurethane urea elastic fiber of the present invention can also be determined by replacing it with the structure of the corresponding organic carboxylic acid. For example, when the organic carboxylic acid used as a starting material is maleic acid (molecular weight 116), the molecular weight is treated as 116 because the organic carboxylic acid used as a starting material is maleic acid, even if maleic anhydride (molecular weight 98) is used as the organic carboxylic acid compound in the method for producing a polyurethane urea elastic fiber of the present invention.

Examples of organic carboxylic acids that can be used as starting materials include methacrylic acid, acetic acid, propiolic acid, acrylic acid, glyoxylic acid, propanoic acid, glycolic acid, methacrylic acid, pyruvic acid, isobutyric acid, butyric acid, oxalic acid, lactic acid, maleic acid, succinic acid, acetoacetic acid, acetic acid, pentanoic acid, malonic acid, glyceric acid, 2-furancarboxylic acid, 3-furancarboxylic acid, sorbic acid, fumaric acid, maleic acid, hexanoic acid, succinic acid, benzoic acid, isonicotinic acid, nicotinic acid, heptanic acid, oxalo acetic acid, glutaric acid, malic acid, anthranilic acid, salicylic acid, octanoic acid, adipic acid, phthalic acid, silicic acid, tartrate acid, tetrahydrophthalic acid, hexahydrophthalic acid, nonanoic acid, hymic acid, isophthalic acid, terephthalic acid, phthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, gallic acid, 2-naphthoic acid, decanoic acid, aconitic acid, citrate, trimellitic acid, dodecanoic acid, pyromellitic acid, benzylic acid, tetradecanoic acid, palmitic acid, dodecenyl succinic acid, heptadecanoic acid, linolenic acid, linoleic acid, oleic acid, stearic acid, tetrachlorophthalic acid, ethylenediaminetetraacetic acid, eicosa pentaenoic acid, arachidonic acid, docosahexaenoic acid, mellitic acid, chlorendic acid, and tetrabromophthalic acid. Organic carboxylic acid-based compounds used in the method for producing a polyurethane urea elastic fiber of the present invention are preferably both the acids themselves and their corresponding acid anhydrides.

Organic carboxylic acids with a molecular weight of 100 or more and 300 or less that can be used as starting materials include succinic acid, acetacetic acid, pentanoic acid, malonic acid, glyceric acid, 2-furancarboxylic acid, 3-furancarboxylic acid, sorbic acid, fumaric acid, maleic acid, hexane acid, succinic acid, benzoic acid, isonicotic acid, nicotinic acid, heptanic acid, oxaloacetic acid, glutaric acid, malic acid, anthranilic acid, salicylic acid, octanoic acid, adipic acid, phthalic acid, cinnamic acid, tartaric acid, tetrahydrophthalic acid, hexahydrophthalic acid, nonanoic acid, hymic acid, isophthalic acid, terephthalic acid, phthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, gluttonic acid, 2-naphthoic acid, decanoic acid, aconitic acid, citric acid, trimellitic acid, dodecanoic acid, pyromellitic acid, benzylic acid, tetradecanoic acid, palmitic acid, dodecenyl succinic acid, heptadecanoic acid, linolenic acid, linolenic acid, oleic acid, stearic acid, tetrachlorophthalic acid, and ethylenediamine tetraacetic acid. These organic carboxylic acids may include any substituent as long as it does not lower the physical properties of the resulting polyurethane urea elastic fiber below the conventional level, and may be used alone or in combinations of two or more. Among organic carboxylic acid-based compounds used in the method for producing polyurethane urea elastic fibers of the present invention, succinic anhydride or phthalic anhydride is preferred.

In the present invention, from the standpoint of improving the yield of polyurethane urea polymer B, the polyurethane urea polymer prior to amide bond formation preferably has a primary or secondary amino group on the end of the molecular chain, and more preferably a primary amino group.

A polyurethane urea elastic fiber with an amide bond in the molecular structure described above contains amino end groups used as the chain extender and/or end capping agent in the range of 0.1 meq or more and 20 meq or less per kilogram of polyurethane urea. By using amino end groups in the range of 20 meq or less per kilogram of polyurethane urea, the physical properties of the polyurethane urea elastic fiber can be stabilized. The mechanism that stabilizes fiber properties is not yet clear, but when a certain amount of amino end groups is present in a polyurethane urea elastic fiber, the linking of fibrous polyurethane urea molecular chains via a solid phase reaction is believed to increase the molecular weight of the polyurethane urea, leading to changes in fiber properties. From the standpoint of even better stabilization of fiber characteristics, the amount of amino end groups in the polyurethane urea elastic fiber is more preferably in the range of 0.1 to 10 meq per kilogram of polyurethane urea. The amount of amino end groups can be identified and quantified in polyurethane urea elastic fibers using analytical methods such as ^X H-NMR and acid-base titration.

In the present invention, the amide bonds in the molecular chain of polyurethane urea polymer B are derived from amino end groups originating with the organic amine and the organic carboxylic acid. From the standpoint of stabilizing spinnability without impairing the stretching performance intrinsic to polyurethane urea elastic fibers, the amount of amide end bonds is preferably in the range of 0.01 meq or more and 10 meq or less per kilogram of polyurethane urea. The amount is more preferably 0.03 meq or more and 5 meq or less per kilogram of polyurethane urea, and even more preferably 0.05 meq or more and 2 meq or less per kilogram of polyurethane urea. The amount of amide bonds can be identified and quantified in polyurethane urea elastic fibers using analytical methods such as ^-NMR and elemental analysis.

From the standpoint of obtaining good spinnability to obtain polyurethane urea elastic fibers from the spinning solution, and achieving a good balance of stretching properties and fiber stability over time in the resulting polyurethane urea elastic fiber, a polyurethane urea elastic fiber of the present invention preferably contains a polyurethane polymer with a tertiary amine in the molecular structure.

Polyurethanes with a tertiary amine in the molecular structure include, for example, a polyurethane and/or a polyurethane urea polymer with a structure containing a tertiary nitrogen-containing diol and/or a tertiary nitrogen-containing diamine and a diisocyanate as starting materials. Others include polymers with an N,N-dialkyl semicarbazide end group. By including a compound with tertiary nitrogen in the main chain and having N,N- dialkylsemicarbazide at the end, a polyurethane urea elastic fiber can be obtained that exhibits high heat resistance during dyeing even with low concentrations of N,N-dialkyl semicarbazide and that has higher strength and elasticity than those lacking this compound.

Specific examples of preferred tertiary nitrogen-containing diols that can be used include N- methyl-N,N-diethanolamine, N-methyl-N,N-dipropanolamine, N-methyl-N,N- diisopropanolamine, N-butyl-N,N-diethanolamine, N-t-butyl-N,N-diethanolamine, N- octadecane-N,N-diethanolamine, N-benzyl-N,N-diethanolamine, N-t-butyl-N,N- diisopropanolamine, and piperazine derivatives such as bishydroxyethyl piperazine and bishydroxyisopropyl piperazine. Especially preferred is N-t-butyl-N,N-diethanolamine or N- benzyl-N,N-diethanolamine.

Specific examples of preferred tertiary nitrogen-containing diamines that can be used include N-methyl-3,3'-iminobis (propylamine), N-butyl-aminobis-propylamine, N-methyl-aminobis- ethylamine, N-t-butyl-aminobis-propylamine, piperazin-N,N'-bis (3-aminopropyl), and piperazin-N,N'-bis (2-aminoethyl). Especially preferred is N-methyl-3,3'-iminobis (propylamine) or piperazine-N,N'-bis (3-aminopropyl).

Preferred examples of diisocyanates serving as a starting material in a polyurethane and/or polyurethane urea polymer having a structure containing a tertiary nitrogen-containing diol and/or tertiary nitrogen-containing diamine and diisocyanate as starting materials include aliphatic diisocyanates such as methylene-bis (4-cyclohexyl isocyanate), isophorone diisocyanate, lysine diisocyanate, and DDI derived from dimer acid. Among these, use of methylene-bis (4-cyclohexyl isocyanate) or isophorone diisocyanate is especially preferred.

The end group in the polyurethane or the polyurethane urea polymer is preferably a semicarbazide group. When reacting with diisocyanate to form a semicarbazide end group, substituted hydrazines are preferably used. Preferred examples of substituted hydrazines include N,N-dimethylhydrazine, N,N-diethylhydrazine, N,N-dipropylhydrazine, N,N-diisopropylhydrazine, N,N-dibutylhydrazine, N,N-diisobutylhydrazine,

N,N-dihydroxyethylhydrazine, and N,N-dihydroxyisopropylhydrazine. Among these, N,N-dimethylhydrazine and N,N-dihydroxyethylhydrazine are especially preferred.

Especially preferred examples of polyurethanes and/or polyurethane urea polymers having a structure containing a tertiary nitrogen-containing diol and/or tertiary nitrogen-containing diamine and diisocyanate as starting materials include a polyurethane obtained by reacting N-t-butyl-N,N-diethanolamine with methylene-bis (4-cyclohexylisocyanate), a polyurethane obtained by reacting N-t-butyl-N,N-diethanolamine with methylene-bis (4-cyclohexylisocyanate) and then reacting the polyurethane with N,N-dimethylhydrazine at the end, and a polyurea obtained by reacting N-methyl-3,3'-iminobis (propylamine) with methylene-bis (4-cyclohexylisocyanate). There are no particular restrictions on the ratio of N-t-butyl-N,N-diethanolamine to methylene-bis (4-cyclohexylisocyanate) as long as the effects of the present invention are not impaired. However, a reaction of about 1 : 1.05 is preferred, where the total of the urethane group concentration to urea group concentration in the alternating copolymer is about 5.1 mol/kg.

A polyurethane urea elastic fiber of the present invention may contain various additives such as stabilizers and pigments. Preferred examples of light stabilizers and antioxidant include hindered phenolic agents such as BHT and Sumilyzer (registered trademark) GA-80 from Sumitomo Chemical Co., Ltd., benzotriazole-based and benzophenone-based agents such as Tinuvin (registered trademark) from Ciba Geigy Co., Ltd., phosphorus-based agents such as Sumilyzer (registered trademark) P-16 from Sumitomo Chemical Co., Ltd., hindered amine agents, pigments such as iron oxide and titanium oxide, minerals such as hydrotalcite compounds, huntite, hydromagnesite, and tourmaline, inorganic materials such as zinc oxide, cerium oxide, magnesium oxide, calcium carbonate, and carbon black, fluorine-based or silicone-based resin powders, metal soaps such as magnesium stearate, disinfectants and deodorizers containing silver, zinc, or compounds of these, lubricants such as silicones and mineral oils, and antistatic agents such as cerium oxide, betaine, and phosphoric acid. These are preferably reacted with the polymers. In order to improve durability with respect to light and various types of nitrogen oxides, a nitrogen oxide supplement such as HN-150 from Nippon Hydrazine Co., Ltd., a thermal oxidation stabilizer such Sumilyzer (registered trademark) GA-80 from Sumitomo Chemical Co., Ltd., or a light stabilizer such as Sumisorb (registered trademark) 300 #622 from Sumitomo Chemical Co., Ltd. is preferably used. In order to improve dispersibility in the fiber to stabilize the spinning process when these stabilizers and pigments are used, an inorganic agent is preferably used which has been surface-treated with organic substances such as fatty acids, fatty acid esters, and polyol- based organic substances, silane-based coupling agents, titanate-based coupling agents, or mixtures thereof.

The method for producing a polyurethane urea elastic fiber of the present invention will now be explained in detail.

The present invention is also a method for producing a polyurethane urea elastic fiber, the method comprising: dry spinning a spinning solution containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having an amino group on at least one end; and polyurethane urea polymer B using a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid as starting materials, and containing an amide bond, wherein the amount of primary or secondary amino groups in polyurethane urea polymer A and polyurethane urea polymer B contained in the spinning solution is in the range of 0.1 meq or more and 25 meq or less per kilogram. By dry spinning a spinning solution in which the amount of primary or secondary amino groups in polyurethane urea polymer A and polyurethane urea polymer B contained in the spinning solution is in the range of 0.1 meq or more and 25 meq or less per kilogram, a polyurethane urea elastic fiber can be obtained in which the amount of primary or secondary amino groups is in the range of 0.1 meq or more and 20 meq or less per kilogram of polyurethane urea elastic fiber. Any method can be used to prepare a spinning solution containing polyurethane urea polymer A and polyurethane urea polymer B.

For example, solution a containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end, and solution b containing polyurethane urea polymer B using a polymer diol, a diisocyanate, an organic amine, and an organic carboxylic acid as starting materials, and containing an amide bond in the molecular chain, can be prepared separately before mixing the two together to obtain a spinning solution. When a spinning solution is obtained using this method, some of solution a containing polyurethane urea polymer A is separated out, and an organic carboxylic acid is added to react with polyurethane urea polymer A to prepare solution b in which polyurethane urea polymer B with an amine bond in the molecular chain has been produced.

In another method, solution a containing polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end is prepared, an organic carboxylic acid is added to solution a and reacted with some of polyurethane urea polymer A to produce polyurethane urea polymer B with an amine bond in the molecular chain from some of polyurethane urea polymer A in solution a, and obtain a spinning solution containing polyurethane urea polymer A and polyurethane urea polymer B.

In another method of obtaining a spinning solution containing polyurethane urea polymer A and polyurethane urea polymer B, a spinning solution of the polyurethane urea polymers can be obtained in which polyurethane urea polymer A and polyurethane urea polymer B co-exist because an organic carboxylic acid has been added but the reaction is not completed. In this method, some unreacted organic carboxylic acid may remain in the spinning solution.

The organic carboxylic acid compound used in these production methods preferably includes a cyclic acid anhydride with a molecular weight of 100 or more and 300 or less.

Other methods that can be used to produce a polyurethane urea polymer include the melt polymerization method and the solution polymerization method. Here, the solution polymerization method is more preferable. The solution polymerization method produces less foreign matter such as gels in the polyurethane urea polymer and produces a polyurethane urea elastic fiber with a low degree of fineness that is easier to spin. The solution polymerization method also does not require the step of preparing solutions.

An example of a polyurethane urea polymer particularly suitable for the present invention is one that is synthesized using PTMG with a number average molecular weight of 1800 or more and 6000 or less as the polymer diol, MDI as the diisocyanate, and at least one of ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, and hexamethylenediamine as the chain extender.

The polyurethane urea polymer can be synthesized in, for example, DMAc, DMF, DMSO or NMP, or a solvent containing any of these as a main component. For example, the raw materials can be placed in the solvent, dissolved, heated to an appropriate temperature, and reacted to obtain a polyurethane urea polymer using the one-shot method or an especially preferred method in which the polymer diol and the diisocyanate are first melt-reacted, and the reaction product is dissolved in a solvent and reacted with a chain extender to obtain a polyurethane urea polymer. When the molecular weight of the polymer diol is 1800 or more, the polymerization is preferably conducted at a ratio of (moles of MDI)/(moles of polymer diol) > 1.5 in order to raise the melting point on the high side to 200°C or more.

In synthesizing such a polyurethane, one type or a mixture of two or more types of catalysts such as amine catalysts and organometallic catalysts is preferably used.

Examples of amine catalysts include N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N,N',N'- tetra methylethylenediamine, N, N, N', N '-tetra methyl- 1,3-propanedia mine, N,N,N',N'- tetramethylhexanediamine, bis-2-dimethylaminoethyl ether, N,N,N',N',N"- pentamethyldiethylenetriamine, tetramethylguanidine, triethylenediamine, N,N'- dimethylpiperazine, N-methyl-N'-dimethylaminoethyl-piperazine, N-(2-dimethylaminoethyl) morpholine, 1-methylimidazole, 1,2-dimethylimidazole, N,N-dimethylaminoethanol, N,N,N'- trimethylaminoethylethanolamine, N-methyl-N'-(2-hydroxyethyl) piperazine, 2,4,6-tris (dimethylaminomethyl) phenol, N,N-dimethylaminohexanol, and triethanolamine.

Examples of organometallic catalysts include tin octanoate, dibutyl tin dilaurate, and lead dibutyl octanoate.

The concentration of polyurethane urea polymers in the resulting polyurethane urea polymer spinning solution is preferably in the range of 30% by mass or more and 80% by mass or less.

In the present invention, a polyurethane urea polymer solution containing polyurethane urea polymer B is obtained by adding an organic carboxylic acid to the polyurethane urea polymer A solution. Any method can be used to add the organic carboxylic acid to the polyurethane urea polymer A solution. Typical methods include using a static mixer, stirring, using a homomixer, and using a twin-screw extruder.

Any reaction conditions can be adopted for a polyurethane urea polymer solution to which an organic carboxylic acid has been added. The reaction conditions include temperature, time, and the presence or absence of a catalyst. There are no particular restrictions because these depend on the reactivity of the organic carboxylic acid with the amino end group in polyurethane urea polymer A. Polyurethane urea polymer B may be obtained by stirring polyurethane urea polymer A and an organic carboxylic acid at 10 to 40°C for 0.5 to 2 hours prior to the spinning operation, and then performing spinning to obtain a polyurethane urea elastic fiber. Alternatively, polyurethane urea polymer A and an organic carboxylic acid may be mixed together prior to spinning, and reactive spinning performed at 100 to 300°C for 10 seconds with the polyurethane urea polymer A and the organic carboxylic acid in an unreacted state to obtain a polyurethane urea elastic fiber in which polyurethane urea polymer B has been produced.

From the standpoint of controlling the viscosity of the polyurethane solution for spinning based on the appropriate spinning conditions, one or more end capping agents is preferably used. Examples include monoamines such as dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, and diamylamine, and monools such as ethanol, propanol, butanol, isopropanol, allyl alcohol, and cyclopentanol.

A basic fiber of the present invention can be obtained using, for example, dry spinning, wet spinning, or melt spinning a spinning stock solution described above, and then winding the fiber. Dry spinning is especially preferred from the standpoint of stable spinning at all finenesses from slender to thick.

There are no particular restrictions on the fineness or cross-sectional profile of a polyurethane urea elastic fiber of the present invention. For example, the cross-sectional profile of the fibers may be circular or flat.

There are no particular restrictions on the dry spinning method, and spinning may be performed after selecting the appropriate spinning conditions for the desired characteristics and the spinning equipment.

For example, because the permanent strain rate and stress relaxation of a polyurethane urea elastic fiber of the present invention are particularly susceptible to the speed ratio between the godet roller and the winder, the spinning conditions are preferably determined based on the intended use for the fiber. From the standpoint of obtaining a polyurethane urea elastic fiber with the desired permanent strain rate and stress relaxation, take up is preferably conducted at a speed ratio between the godet roller and the winder in the range of 1.10 or more and 1.65 or less. Also, from the standpoint of improving the strength of the resulting polyurethane urea elastic fiber, the spinning speed is preferably 250 m/min or more.

[Examples]

The present invention will now be described in greater detail with reference to examples. However, the present invention is not limited to these examples.

< Method for Preparing Polyurethane Urea Polymer A >

■ Solution al

Polymerization was carried out in the usual manner using PTMG with a molecular weight of 1800 as the polymer diol, MDI as the diisocyanate, ethylenediamine as the organic amine, and diethylamine as the end capping agent, and a DMAc solution (concentration 35% by mass) of polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end, was prepared. This was designated as solution a l.

■ Solution a2

Polymerization was carried out in the usual manner using 3M-PTMG with a molecular weight of 3500 as the polymer diol, MDI as the diisocyanate, ethylenediamine as the organic amine, and diethylamine as the end capping agent, and a DMAc solution (concentration 35% by mass) of polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end, was prepared. This was designated as solution a2.

■ Solution a3

Polymerization was carried out in the usual manner using PTMG with a molecular weight of 1800 as the polymer diol, MDI as the diisocyanate, 1,2-propanediamine as the organic amine, and diethylamine as the end capping agent, and a DMAc solution (concentration 35% by mass) of polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end, was prepared. This was designated as solution a3.

■ Solution a4

Polymerization was carried out in the usual manner using PTMG with a molecular weight of 2900 as the polymer diol, MDI as the diisocyanate, ethylenediamine as the organic amine, and cyclohexyl as the end capping agent, and a DMAc solution (concentration 35% by mass) of polyurethane urea polymer A having a molecular chain using a polymer diol, a diisocyanate, and an organic amine as starting materials, and having a primary or secondary amino group on at least one end, was prepared. This was designated as solution a4.

< Method for Preparing Polyurethane Urea Polymer B >

First, 1 to 10% by mass of a DMAc solution of an organic carboxylic acid (solution cy [where y is 1 to 6, see below] concentration 35% by mass) is added to 90 to 99% by mass of the DMAc solution of polyurethane urea polymer A (solution ax [where x is 1 to 4, see above] concentration 35% by mass), and then mixed together. This was mixed continuously at 20 to 40°C for 0.5 to 2 hours under a nitrogen atmosphere to prepare a DMAc solution (concentration 35% by mass) of polyurethane urea polymer A and polyurethane urea polymer B containing an amide bond in the molecular chain. This was designated as solution b. Note that solution b is referred to below as "solution xby" depending on the polymer B raw materials contained therein (solution ax and solution cy).

< Amount of Primary or Secondary Amino Groups at the End of the Polyurethane Urea Molecule per Kilogram of Polyurethane Urea Elastic Fiber >

The amount of amino groups at the end of the polyurethane urea molecule per kilogram of polyurethane urea elastic fiber was measured using acid-base titration.

< Evaluation Methods >

[1] Elastic Fiber Properties

In order to measure the basic properties and stability over time of the elastic fibers, a tensile test was carried out on a sample fiber using an Instron 4502 tensile tester under the following conditions.

First, a 5 cm (LI) sample was elongated by 300% five times at a tensile rate of 50 cm/min, and the stress after elongation by 300% the fifth time was defined as (Gl). The sample length was then held at elongation of 300% for 30 seconds. The stress after holding the elongated fiber for 30 seconds was defined as (G2). Next, when the elongated sample was restored and the stress had reached 0, the length of the sample was defined as (L2). The sample was then elongated for a sixth time until it broke. The stress at break was defined as (G3), and the sample length at break was defined as (L3). Also, the strain and stress at the time of recovery after holding the elongated sample for 30 seconds for the fifth time was plotted and a curve was drawn. The stress under 200% strain was calculated as (P-200), and the strength in the actual usage range of the expansion and contraction properties at a predetermined fineness (22 dtex) was calculated as (G4).

The number of measurements was n = 3, and the average value was used to calculate the properties described above. (1) Basic Properties of the Elastic Fiber

The basic properties of an elastic fiber are breaking strength, elongation at break, and permanent strain rate, and these were measured.

■ Breaking strength (cN) = (G3)

■ Elongation at break (%) = 100 x ((L3)-(L1))/(L1)

■ Permanent strain rate (%) = 100 x ((L2)-(L1))/(L1)

(2) Elastic Fiber Stability Over Time

The change in strength over time in the actual usage range and the change in strain rate over time were measured as the stability of the elastic fiber over time. The day on which the test fiber was collected after spinning was set as day 0. After storage at a temperature of 21°C and a humidity of 60%, the physical characteristics of the test fiber were measured after one day and after three months, and the characteristics were calculated using the following equations.

■ Change in strength over time in the actual usage range (%) = [(strength of the fiber in the actual usage range three months after spinning)/(strength of the fiber in the actual usage range one day after spinning)] x 100

■ Change in strain rate over time (%) = [(permanent strain rate of the fiber three months after spinning)/(permanent strain rate of the fiber one day after spinning)] x 100

At this time, the strength in the actual usage range was calculated using the following equation.

■ Strength in the actual usage range (cN) = (G4)

Here, a smaller difference in the physical property values of the polyurethane urea elastic fiber one day and three months after spinning indicates better stability over time. The change in strength over time in the actual usage range and the change in strain rate over time were evaluated using the following criteria : 90% or more and less than 120% means especially excellent stability over time (©), 85% or more and less than 90% or 120% or more and less than 125% means excellent stability over time (o), and less than 85% or more than 125% means residual problems with stability over time (x).

[2] Spinnability of Elastic Fibers

Spinning was continuously performed for 48 hours, and the number of broken fibers after that time was used as an index for determining spinnability. After continuous spinning for 48 hours, less than two fiber breaks was considered excellent (©). More than two fiber breaks over 48 hours but less than two fiber breaks over 24 hours was considered good (o). More than two fiber breaks over 24 hours was considered poor (x).

[Example 1]

Solution a l was prepared as solution a, which was a DMAc solution of polyurethane urea polymer A using the method described in Method for Preparing Polyurethane Urea Polymer A. Solution Ibl was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B using the following in the method described in Method for Preparing Polyurethane Urea Polymer B.

■ Solution cl was prepared as a DMAc solution of an organic carboxylic acid using succinic anhydride as the organic carboxylic acid. The molecular weight of succinic acid, which is the carboxylic acid corresponding to succinic anhydride, is 118.09.

■ Solution Ibl was prepared from solution al and solution cl. In preparing solution Ibl, solution al was added in an amount of 98% by mass and solution cl was added in an amount of 2% by mass, and the contents were uniformly mixed together for one hour at 25°C.

A DMAc solution of a polyurethane (Metachlor (registered trademark) 2462 from DuPont) (concentration 35% by mass) produced by a reaction between t-butyldiethanolamine and methylene-bis-(4-cyclohexylisocyanate) was prepared, and this, including other additives, was designated as tl.

Solutions al, Ibl and tl were uniformly mixed together at 98.9% by mass, 0.1% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and this spinning solution was dry-spun and wound at a spinning speed of 600 m/min with the godet roller and winder speed ratio set at 1.2, to obtain a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 2]

Solutions al, Ibl and tl were uniformly mixed together at 98.0% by mass, 1.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 3]

Solutions al, Ibl and tl were uniformly mixed together at 97.0% by mass, 2.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 4]

Solutions al, Ibl and tl were uniformly mixed together at 91.0% by mass, 8.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 5]

Solutions al, Ibl and tl were uniformly mixed together at 84.0% by mass, 15.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 6]

In place of solution cl, solution c2 was prepared according to the method described in Example 1 as a DMAc solution of an organic carboxylic acid using terephthalic acid. Solution lb2 obtained from solution al and solution c2 was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B.

Solutions al, lb2 and tl were uniformly mixed together at 98.9% by mass, 0.1% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 7]

Solutions al, lb2 and tl were uniformly mixed together at 97.0% by mass, 2.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 8]

In place of solution cl, solution c3 was prepared according to the method described in Example 1 as a DMAc solution of an organic carboxylic acid using acetic acid. Solution lb3 obtained from solution al and solution c3 was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B.

Solutions al, lb3 and tl were uniformly mixed together at 98.9% by mass, 0.1% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 9]

Solutions al, lb3 and tl were uniformly mixed together at 87.0% by mass, 12.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 10]

In place of solution cl, solution c4 was prepared according to the method described in Example 1 as a DMAc solution of an organic carboxylic acid using ethylenediamine tetraacetic acid. Solution lb4 obtained from solution al and solution c4 was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B. Solutions al, lb4 and tl were uniformly mixed together at 98.0% by mass, 1.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 11]

Solutions al, lb4 and tl were uniformly mixed together at 86.0% by mass, 13.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 12]

In place of solution cl, solution c5 was prepared according to the method described in Example 1 as a DMAc solution of an organic carboxylic acid using succinic acid. Solution lb5 obtained from solution al and solution c5 was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B.

Solutions al, lb5 and tl were uniformly mixed together at 98.0% by mass, 1.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 13]

In place of solution cl, solution c6 was prepared according to the method described in Example 1 as a DMAc solution of an organic carboxylic acid using acetic anhydride. Solution lb6 obtained from solution al and solution c6 was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B.

Solutions al, lb6 and tl were uniformly mixed together at 98.0% by mass, 1.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 14]

Solution a2 was prepared as solution a, which was a DMAc solution of polyurethane urea polymer A. Solution 2bl obtained from solution a2 and solution cl was prepared as solution b, which was a DMAc solution of polyurethane urea polymer B.

Solutions a2, 2bl and tl were uniformly mixed together at 98.9% by mass, 0.1% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2. [Example 15]

Solutions a2, 2bl and tl were uniformly mixed together at 84.0% by mass, 15.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 16]

Solutions al, 2bl and tl were uniformly mixed together at 98.0% by mass, 1.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 17]

Solutions a2, Ibl and tl were uniformly mixed together at 91.0% by mass, 8.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 18]

Solutions al and Ibl were uniformly mixed together at 99.9% by mass and 0.1% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Example 19]

Solutions al and Ibl were uniformly mixed together at 98.0% by mass and 2.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Comparative Example 1]

Solutions al and tl were uniformly mixed together at 99.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Comparative Example 2]

Solutions a2 and tl were uniformly mixed together at 99.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Comparative Example 3]

Solutions a3 and tl were uniformly mixed together at 99.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Comparative Example 4]

Solutions a4 and tl were uniformly mixed together at 99.0% by mass and 1.0% by mass, respectively, to obtain a spinning solution, and a 22 dtex, 2 fil multifilament polyurethane urea elastic fiber was prepared using the method described in Example 1. The composition of this polyurethane urea elastic fiber is shown in Table 1, and the properties of this fiber are shown in Table 2.

[Table 1A]

[Table IB]

[Table 1C]

[Table ID]

[Table 2A]

[Table 2B]

[Table 2C]

[Table 2D]

[Industrial Applicability]

Because the polyurethane urea elastic fibers of the present invention have high elasticity and a low residual strain rate, clothes using these elastic fibers have a good fit and feel, and are easy to take off. Because these elastic fibers also have stable mechanical properties over time, they are easy to process in the covering, knitting, and weaving process, whether used alone or in combination with other types of fibers for higher-order processing.

Because polyurethane urea elastic fibers of the present invention have these excellent properties, they can be used alone or in combination with other types of fibers to obtain excellent stretch fabrics, and are suitable for knitting, weaving and cord processing. Specific applications in which these fibers can be used include in tightening materials for various textile products such as socks, stockings, circular knits, tricot knits, swimwear, ski pants, work clothes, firefighting clothes, golf pants, wet suits, brassieres, girdles, gloves and socks, tightening materials for preventing leakage from sanitary products such as disposable diapers, tightening materials for waterproof materials, imitation bait, artificial flowers, electrical insulation, wiping cloths, copier cleaners, and gaskets.