Polyurethane Elastic Thread and Production Method Therefor [Technical Field]

The present invention relates to a polyurethane elastic fiber with excellent antibacterial properties and excellent yellowing resistance, a polyurethane elastic fiber suitable for obtaining a fabric having antibacterial properties, and a production method therefor.

[Background Art]

Because of their superior elastic properties, elastic fibers are used in a wide range of applications, including elastic clothing applications such as legwear, innerwear and sportswear, sanitary applications such as disposable diapers and sanitary napkins (as a protective material), and industrial applications.

In order to meet growing demand for a more comfortable living environment, so-called "antibacterial products" have become popular in recent years. These products include antibacterial paints, antibacterial films and sheets, antibacterial filaments, antibacterial toiletry products, antibacterial kitchen utensils, antibacterial writing instruments, antibacterial sand, antibacterial tissues, antibacterial fibers, and antibacterial cosmetics.

Many different inorganic antibacterial agents are used as antibacterial agents in these products, especially silver antibacterial agents.

These inorganic antibacterial agents have better weather and chemical resistance and lower acute oral toxicity than organic antibacterial agents. Also, because their heat resistance is significantly higher than that of organic antibacterial agents, they have been added to synthetic resins used in many fields.

Examples of the metal ions constituting inorganic antibacterial agents include silver, mercury, copper, zinc, and tin ions. Silver ions and copper ions are especially used. When these are supported on a material with a porous structure such as glass, zeolite, silica gel, silicate, whiskers, alumina, and ceramics, an excellent antibacterial effect can be realized. Many techniques have been proposed for use on these fibers (Patent Documents 1-3).

However, when a synthetic resin containing an added inorganic antibacterial agent is molded, problems occur with gelation of the synthetic resin and changes in its molecular weight due to the cross-linking action and catalytic action of the metal in the inorganic antibacterial agent. Also, the value of the resulting product is significantly reduced by thermal discoloration during molding, discoloration due to exposure of the molded product to NOx gas, and discoloration due to exposure of the molded product to light.

Therefore, techniques for suppressing discoloration of antibacterial resins containing an added inorganic antibacterial agent have been proposed (Patent Document 4). However, while these techniques provide a certain level of antibacterial performance, significant yellowing occurs in certain environments and over time, and it cannot be said that the problem has been solved sufficiently.

[Prior Art Documents] [Patent Documents]

[Patent Document 1] JP H05-339810 A [Patent Document 2] JP H06-093565 A [Patent Document 3] JP 2017-040007 A [Patent Document 4] JP 4485871 B2 [Summary of the Invention]

[Problem to Be Solved by the Invention]

It is an object of the present invention to provide a polyurethane elastic fiber with excellent antibacterial properties and excellent yellowing resistance.

[Means for Solving the Problem]

The present invention solves this problem using the following means.

(1) A polyurethane elastic fiber whose main component is a polyurethane whose main starting materials are a polymer diol and a diisocyanate, wherein the polyurethane elastic fiber comprises (a) a slowly water-soluble glass containing a Group IB and/or Group 2B element and (b) a nonionic surfactant.

(2) A polyurethane elastic fiber according to (1), wherein the amount of (a) is 0.1% by mass or more and 30% by mass or less.

(3) A polyurethane elastic fiber according to (1) or (2), wherein the average primary particle size of (a) is 3.0 pm or less.

(4) A polyurethane elastic fiber according to any one of (1) to (3), wherein (a) is a slowly water-soluble glass containing silver and/or a slowly water-soluble glass containing copper.

(5) A polyurethane elastic fiber according to any one of (1) to (4), wherein (b) is a polyoxyethylene alkyl ether.

(6) A polyurethane elastic fiber according to any one of (1) to (5), wherein the polyurethane elastic fiber further comprises a quaternary ammonium salt-based antibacterial agent.

(7) A method for producing a polyurethane elastic fiber, the method comprising: mixing (a) a slowly water-soluble glass containing a Group IB and/or Group 2B element with a spinning solution; mixing in a nonionic surfactant in an amount within a range of 0.01% by mass or more and 20% by mass or less relative to the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element; and dry spinning the spinning solution.

(8) A method for producing a polyurethane elastic fiber according to (7), wherein (a) a slowly water-soluble glass containing a Group IB and/or Group 2B element is mixed as a dispersion solution with a spinning solution containing a polyurethane whose main starting materials are a polymer diol and a diisocyanate. (9) A method for producing a polyurethane elastic fiber according to (7) or (8), wherein the (a) Group IB and/or Group 2B element is silver and/or copper.

(10) A method for producing a polyurethane elastic fiber according to any one of (7) to (9), wherein (b) is a polyoxyethylene alkyl ether.

[Effect of the Invention]

The present invention is able to obtain a polyurethane elastic fiber with excellent antibacterial properties, discoloration resistance, and elasticity whose main component is a polyurethane whose main starting materials are a polymer diol and a diisocyanate, in which the polyurethane elastic fiber comprises (a) a slowly water-soluble glass containing a Group IB and/or Group 2B element and a nonionic surfactant. A fabric using this polyurethane elastic fiber has excellent antibacterial properties, discoloration resistance, and elasticity.

[Mode for Carrying Out the Invention]

The present invention will now be described in detail.

The polyurethane used as a main component of the polyurethane elastic fiber will be described first. Here, main component means a component constituting more than 50% by mass of the polyurethane elastic fiber.

There are no particular restrictions on the polyurethane used in the present invention. It may be any polyurethane as long as it has a structure whose main starting materials are a polymer diol and a diisocyanate. Here, a polymer diol and a diisocyanate as starting materials means the resulting polyurethane polymer has a structure derived from these components. In the present specification, the structure of a polyurethane polymer obtained by using a polymer diol and a diisocyanate as starting materials is specified. An equivalent structure may be formed from different raw materials, and the raw materials themselves are not specified. There are also no particular restrictions on the synthesis method that is used. For example, it may be a polyurethane urea composed of a polymer diol, a diisocyanate, and a low molecular weight diamine serving as a chain extender, or may be a polyurethane urethane composed of a polymer diol, a diisocyanate, and a low molecular weight diol serving as a chain extender. It may also be a polyurethane urea using a compound with a hydroxyl group and an amino group in the molecule as a chain extender. Polyfunctional glycols and isocyanates having trifunctionality or higher may also be used as long as the effects of the present invention are not impaired. Here, a polyurethane whose main starting materials are a polymer diol and a diisocyanate means more than 50% by mass of the isocyanate compounds among the starting materials is a diisocyanate and more that 50% by mass of the components reacting with the isocyanate compounds among the starting materials (polymer diols, low molecular weight diamines, low molecular weight diols, compounds with hydroxyl groups and amino groups in their molecules, polyfunctional glycols, etc.) is a polymer diol. When calculating the mass ratios, the use of these components as starting materials is assumed regardless of the actual raw materials that are used. Among the diol compounds, a low molecular weight diol means a compound having a molecular weight of less than 500, and diol compounds having a molecular weight of 500 or more are called polymer diols (the same applies to diamine compounds).

The polymer diol is preferably a polyether-based diol, a polyester-based diol, or a polycarbonate diol. A polyether diol is preferably used from the standpoint of imparting flexibility and elasticity to the fabric. Preferred examples of polyether diols include polyethylene oxide, polyethylene glycol, polyethylene glycol derivatives, polypropylene glycol, polytetramethylene ether glycol (PTMG), modified PTMG that is a copolymer of tetrahydrofuran (THF) and 3- methyltetrahydrofuran, modified PTMG that is a copolymer of tetrahydrofuran (THF) and 2- dimethyl tetrahydrofuran, modified PTMG that is a copolymer of 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 a polyurethane elastic fiber with 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 molecular weight of the polymer diol used in the present invention is preferably 1,000 or more and 8,000 or less, and more preferably 1,500 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 easily obtained.

The aromatic diisocyanates used in the present invention 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), isophorone diisocyanate, methylcyclohexane 2,4-diisocyanate, methylcyclohexane 2,6-diisocyanate, cyclohexane 1,4- diisocyanate, hexahydroxylylene diisocyanate, hexahydrotolylene diisocyanate, and octahydro-l,5-naphthalenediisocyanate. Aliphatic diisocyanates are especially effective for suppressing the yellowing of polyurethane elastic fibers. These diisocyanates may be used alone or in combinations of two or more.

The chain extender used in the present invention is preferably at least one of a low molecular weight diamine and a low molecular weight diol. The molecule may also have a hydroxyl group and an amino group such as ethanolamine.

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 easily 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.

Typical examples of low molecular weight diols include ethylene glycol, 1,3 propanediol, 1,4 butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, and l-methyl-1,2- ethanediol. These may be used alone or in combinations of two or more. Use of 1,3 propanediol and 1,4 butanediol is especially preferred. When these are used, the diol- extended polyurethane has higher heat resistance and a stronger fiber can be obtained.

From the standpoint of obtaining fibers with high durability and strength, the number average 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. The molecular weight is measured by GPC and converted in terms of polystyrene.

One or more end blockers is preferably mixed into a polyurethane elastic fiber of the present invention. Preferred examples of end blockers 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.

In the present invention, a polyurethane elastic fiber composed of a polyurethane with the basic configuration described above can maintain excellent antibacterial properties by including (a) a slowly water-soluble glass containing a Group IB element and/or a Group 2B element as well as a nonionic surfactant.

The slowly water-soluble glass is a silicate glass that is generally water-insoluble, that is, a glass produced by blending a total of 30% by mass or more P2O5 and/or B2O3 with S1O2, which is the main raw material, that slowly dissolves in water. The slowly water-soluble glass used in the present invention only needs to be able to retain (a) a Group IB element and/or Group 2B element. In addition to a general slowly water-soluble glass that uses S1O2 as the main raw material, it may be composed of P2O5 and/or B2O3, which can be vitrified themselves, as the main raw material, and not contain any S1O2 at all. When there is less than 30% by mass of P2O5 and/or B2O3 with S1O2 in (a) a slowly water-soluble glass of the present invention, elution of the Group IB element and/or Group 2B element ions during the water-based processing steps for polyurethane elastic fibers such as the dyeing step become unsuccessful, and the antibacterial effect is insufficient.

In the present invention, the Group IB element and/or Group 2B element in the (a) slowly water-soluble glass is preferably added in raw material form as an oxide. Examples of oxides of (a) Group IB element and/or Group 2B element include AgO, Ag20, Ag2C>3, CuO, CU2O, ZnO, and AU2O3. From the standpoint of antibacterial properties, the oxidation number of the (a) Group IB element and/or Group 2B element is preferably as low as possible while providing a stable material, and the oxide is more preferably Ag _å 0 or CuO. Preferably, the oxide of the (a) Group IB element and/or the Group 2B element is blended into a phosphoric acid-based and/or boric acid-based slowly water-soluble glass powder in a total amount of 1% by mass or more on a raw material basis.

A polyurethane elastic fiber having an antibacterial function can be produced with various methods using this phosphoric acid-based slowly water-soluble glass and/or boric acid- based (a) slowly water-soluble glass containing a Group IB element and/or a Group 2B element. These (a) slowly water-soluble glasses containing a Group IB element and/or a Group 2B element may be used alone or in a mixture of two or more. There are no particular restrictions on the method used to produce the slowly water-soluble glass, but a melt quenching method or sol-gel method is preferred. In addition to the components described above, trace amounts of SrO, BaO, T1O2, ZrC>2, Nb20s, CS2O, Rb20, TeC>2, BeO, GeC>2, B12O3, La2C>3, Y2O3, WO3, M0O3, or Fe2C>3 can be included in the glass solid solution during production of the slowly water-soluble glass. Also, F, Cl, SO3, Sb2C>3, SnC>2, or Ce may be added as a clarifying agent.

The amount of (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is preferably in the range of from 0.1% by mass or more and 30% by mass or less relative to the total mass of the polyurethane elastic fiber. When the amount of (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is less than 0.1% by mass, it is sometimes difficult to obtain sufficient antibacterial properties when used as a fabric. More preferably, the amount is 0.5% by mass or more. When the amount exceeds 30% by mass, it may cause a deterioration in elastic properties and be unfavorable in terms of cost. The amount is preferably 10% by mass or less, and more preferably 5.0% by mass or less. From the standpoint of antibacterial properties and the balance between physical properties and cost, the range is more preferably 1.0% by mass or more and 5.0% by mass or less.

In the present invention, from the standpoint of suppressing clogging of the spinning solution in the spinneret, the average primary particle size of the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is preferably 3.0 pm or less. More preferably, it is 1.5 pm or less. From the standpoint of dispersibility, the cohesive force increases and it becomes difficult to mix the spinning solution uniformly when the average primary particle size is smaller than 0.05 pm. Therefore, an average primary particle size of 0.05 pm or more is preferred. More preferably, it is 0.15 pm or more. The average primary particle size is determined using an electron microscope. For example, the equivalent of the projected area circle for primary particles is generated by image processing in an interval between two parallel lines in a certain direction that interpose the primary particles in a field magnified by a factor of tens of thousands. Twenty of the diameters are randomly measured, the upper 5% (maximum values) and lower 5% (minimum values) are removed based on a number standard, and the average value of the remaining 90% (values for 18 particles) is calculated. The particle size distribution is preferably obtained by dividing the average primary particle size by the most frequent particle size (mode diameter) from 0.5 to 1.5, and more preferably 0.8 to 1.2. Preferably, the maximum particle size is distributed within 2.0 times the average primary particle size, and more preferably 1.5 times or less.

In the present invention, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is preferably distributed uniformly in the polyurethane. Various known surfactants can be used as dispersants to disperse the glass. However, it has been found that a nonionic surfactant should be used to uniformly disperse the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element in the polyurethane and obtain polyurethane elastic fibers with excellent spinnability, antibacterial properties, discoloration resistance, and elasticity. It has also been found that use of a nonionic surfactant has a synergistic effect, especially on antibacterial properties. Meanwhile, ionic surfactants such as anionic surfactants, cationic surfactants, and anionic-cationic amphoteric surfactants often do not exhibit antibacterial properties after undergoing the required water-based treatment steps for fabrics, such as dyeing.

Examples of nonionic surfactants that can be used in the present invention include polyoxyethylene alkyl ethers, alkyl monoglyceryl ethers, polyoxyethylene alkyl amines, fatty acid sorbitan esters, and fatty acid diethanolamides. Among these, the so-called hydrophilic portion (hydrophil) of the surfactant is preferably an ether, and is preferably at least one of an ethylene oxide polymer, a propylene oxide polymer, and an ethylene oxide/propylene oxide copolymer. By including at least one of a terminal-modified derivative of an ethylene oxide polymer, a terminal-modified derivative of a propylene oxide polymer, and a terminal- modified derivative of an ethylene oxide/propylene oxide copolymer as the nonionic surfactant, antibacterial properties can be improved while enhancing spinnability. The so- called hydrophobic portion (hydrophob) of the surfactant can be one of the terminally modified structures mentioned above. However, alkyl groups, phenyl groups, and styrenated phenyl groups are preferred. Specific examples of nonionic surfactants include polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene ethylphenol ether, polyoxyethylene propyl phenol ether, polyoxyethylene styrylated phenyl ether, and polyoxyethylene sorbitol tetraoleate. Especially preferred are polyoxyethylene styrenated phenyl ethers, such as polyoxyethylene oxypropylene tris styrenated phenyl ether, polyoxyethylene oxypropylene distyrene phenyl ether, polyoxyethylene oxypropylene monostyrene phenyl ether, polyoxyethylene oxypropylene-2,4,6-tris (a,a-dimethylbenzyl) phenyl ether, polyoxyethylene oxypropylene-2,4-bis (a,a-dimethylbenzyl) phenyl ether, polyoxyethylene oxypropylene-2-mono (a,a-dimethylbenzyl) phenyl ether, and polyoxyethylene oxypropylene-4-mono (a,a-dimethylbenzyl) phenyl ether. Most preferred is use of a mixture in which the number of added moles of these styrene groups has a distribution.

In the present invention, a quaternary ammonium salt-based antibacterial agent is preferably also used. It is important to keep skin sensitivity at the proper antibacterial level, especially in textile structures for clothing, medical fabrics, and protective materials. Even though the slowly water-soluble glass containing a Group IB and/or Group 2B element is a completely inorganic substance, the organic quaternary ammonium salt-based antibacterial agent is easily distributed on the surface layer of polyurethane elastic fiber. Because elution of quaternary ammonium proceeds more rapidly, it is easy to control the initial antibacterial performance of the quaternary ammonium salt-based antibacterial agent immediately after production or immediately after fabric processing such as dyeing. Because elution of the Group IB and/or Group 2B element in the slowly water-soluble glass containing a Group IB and/or Group 2B element proceeds more slowly, the required level for antibacterial properties can be maintained even after repeated washing and long-term aging by adjusting, for example, the amount added and the particle size. In this way, by using antibacterial agents with different elution rates as antibacterial components in the polyurethane elastic fiber, the antibacterial properties can be designed to remain at the optimum level of the initial state after long-term aging. When a quaternary ammonium salt- based antibacterial agent is also used, the antibacterial activity differs depending on the chain length of the alkyl group in the ammonium ion, and the antibacterial activity is preferably strong. However, from the standpoint of suppressing thermal decomposition caused by heat during production of the polyurethane elastic fiber and from the standpoint of suppressing ionicity that inhibits elution of the (a) Group IB element and/or Group 2B element from the (a) slowly water-soluble glass containing a Group IB element and/or Group 2B element, a chain type such as an alkyl group, and an alkyl group having a long chain length, that is, an alkyl group having a large number of carbon atoms, is preferably selected. From this standpoint, ammonium ions that are especially preferred are didecyldimethyl ammonium ions and oleyltrimethyl ammonium ions. The counter anions that constitute the quaternary ammonium salt should also be taken into consideration.

These are usually supplied by inorganic salts such as chlorides, bromides and iodides, and organic acid salts such as carboxylates, sulfonates and phosphates. From the standpoint of stability with respect to discoloration and heat resistance and improvement of breaking strength and elongation, carboxylates and sulfonates are preferred, and carboxylates are most preferred.

Specific examples of salts with this structure include didecyldimethylammonium carboxylates such as didecyldimethylammonium adipate, didecyldimethylammonium gluconate and didecyldimethylammonium propionate, oleyltrimethylammonium carboxylates such as oleyl trimethylammonium adipate and oleyltrimethylammonium gluconate, and sulfonates such as didecyldimethylammonium trifluoromethylsulfonate, di-n- decyldimethylammonium trifluoromethanesulfonate, di-n-decyldimethylammonium pentafluoroethane sulfonate, n-hexadecyltrimethylammonium trifluoromethanesulfonate, and benzyldimethyl coconut oil alkylammonium pentafluoroethane sulfonates.

From the standpoint of exhibiting antibacterial properties and maintaining a good balance between discoloration and elasticity characteristics, the amount of quaternary ammonium salt-based antibacterial agent is preferably in a range of from 0.1% by mass or more and 5% by mass or less relative to the total mass of the polyurethane elastic fiber. A polyurethane elastic fiber of the present invention may contain various additives such as stabilizers and pigments. Preferred examples of light stabilizers and antioxidants 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.

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

In the present invention, a polymer diol and a diisocyanate are used as the main starting materials, and the polyurethane spinning solution obtained from these that is dry-spun contains (a) a slowly water-soluble glass including a Group IB element and/or Group 2B element and a nonionic surfactant. The (a) slowly water-soluble glass containing a Group IB element and/or a Group 2B element is mixed with the nonionic surfactant. When the polyurethane spinning solution is prepared, the nonionic surfactant is admixed in a range of 0.01 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the (a) slowly water-soluble glass including a Group IB element and/or Group 2B element. More preferably, the nonionic surfactant is kneaded beforehand into a fine powder obtained in the step in which the (a) slowly water-soluble glass including a Group IB element and/or Group 2B element is pulverized to coat the fine powder with the nonionic surfactant. A polyurethane solution or polyurethane as the solute in a solution may be prepared using melt polymerization, solution polymerization, or some other method. However, the solution polymerization method is especially preferred. In the solution polymerization method, not many foreign substances such as gels are produced in the polyurethane, the spinning solution is easy to spin, and a polyurethane elastic fiber with a low degree of fineness is easy to obtain. Of course, the solution polymerization method is also advantageous in that a step of making a solution can be omitted.

A polyurethane that is especially suitable for the present invention is synthesized using PTMG with a number average molecular weight of 1,500 or more and 6,000 or less as the polymer diol, MDI as the diisocyanate, and at least one type among ethylenediamine, 1,2- propanediamine, 1,3-propanediamine, and hexamethylenediamine as the chain extender. Polyurethane can be obtained by synthesizing the raw materials described above in, for example, dimethylacetamide (DMAc), dimethyl sulfoxide (DMF), dimethyl sulfoxide (DMSO), n-methylpyrrolidinone (NMP), or a solvent whose main components are these. Preferred methods include the so-called one-shot method, in which the raw materials are added to a solvent, dissolved, heated to an appropriate temperature, and reacted to form a polyurethane, and a method in which a polymer diol and diisocyanate are melt-reacted, and the reaction product is dissolved in a solvent and reacted with the chain extender to obtain a polyurethane.

When a diol is used as a chain extender, adjusting the polyurethane melting point on the high side to a range of 200°C or higher and 260°C or lower is preferred from the standpoint of obtaining excellent heat resistance. This is typically achieved by controlling the types and ratios of polymer diols, MDIs, and diols used. When the molecular weight of the polymer diol is low, a polyurethane with a high melting point can be obtained by increasing the relative ratio of MDI. Similarly, when the molecular weight of the diol is low, a polyurethane with a high melting point can be obtained by reducing the relative ratio of the polymer diol.

When the molecular weight of the polymer diol is 1,800 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 these polyurethanes, 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'- tetramethylethylenediamine, 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-dimethyla mi noethyl) 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 polymer solution is preferably in the range of 30% by mass or more and 80% by mass or less.

In the present invention, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant are added to this polyurethane solution. Any method can be used to add the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant to the polyurethane solution. Examples include using a static mixer, stirring, using a homomixer, and using a biaxial extruder.

In the present invention, in order to improve the antibacterial properties, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is added to the polyurethane elastic fiber in the range of 0.5% by mass or more and 10% by mass or less. Therefore, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element has to be uniformly dispersed in the polyurethane spinning solution prior to spinning in the range of 0.5% by mass or more and 10% by mass or less. Preferably, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant are added to a polyurethane spinning solution using, for example, N,N- dimethylformamide or N,N-dimethylacetamide, etc. as a solvent, and are then mixed while stirring to uniformly disperse the components. More preferably, the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant are dispersed beforehand in the N,N-dimethylformamide or N,N-dimethylacetamide solvent, to obtain a dispersion solution of the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element, and this dispersion solution is mixed into the polyurethane spinning solution. Here, the solvent added to the dispersion solution of the (a) slowly water- soluble glass containing a Group IB and/or Group 2B element is preferably the same solvent used in the polyurethane solution from the standpoint of uniformly adding the dispersion solution to the polyurethane solution. Pigments and chemical agents such as light-resistant agents and antioxidants may be added at the same time the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element is added to the polyurethane solution. Also, from the standpoint of exhibiting antibacterial properties, the dispersion solution is prepared beforehand by mixing together the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant and then added to the polyurethane spinning solution.

The present invention also preferably contains a quaternary ammonium salt-based antibacterial agent in order to enhance antibacterial properties against various bacteria. Here, the quaternary ammonium salt-based antibacterial agent is added to the polyurethane spinning solution before spinning is performed. The quaternary ammonium salt-based antibacterial agent may be simply mixed into the polyurethane spinning solution or may be mixed into the dispersion solution of the (a) slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant beforehand. Preferably, the mixing order is mixing the slowly water-soluble glass containing a Group IB and/or Group 2B element and the nonionic surfactant together to create a dispersion solution, mixing the quaternary ammonium salt-based antibacterial agent into the dispersion solution, and then mixing the dispersion solution into the polyurethane spinning solution. Most preferably, the quaternary ammonium salt-based antibacterial agent is included in the spinning solution by simply mixing the quaternary ammonium salt-based antibacterial agent with the spinning solution independent of the dispersion solution obtained beforehand by mixing theslowly water-soluble glass containing a Group IB and/or Group 2B element with the nonionic surfactant.

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

There are no particular restrictions on the fineness or cross-sectional profile of a polyurethane 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 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 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 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, but the present invention is not limited to these examples.

[NOx Anti-Yellowing Properties]

A sample card was prepared by winding 10 g of the polyurethane elastic fiber on a stainless steel plate. This sample was exposed to a gas consisting of air and a specified concentration (7 ppm) of NO2 gas for 50 hours using a Scott tester. The "b" color was measured before and after this exposure treatment using a color master (D25 DP-9000 signal processor), and the degree of yellowing was the difference "Ab" before and after the treatment. The measured value used is the average value of n = 3.

[Average Primary Particle Size]

Inorganic particles were photographed using an S-800 electrolytic radiation scanning electron microscope (FE-SEM) from Hitachi, Ltd. and analyzed using the image processing software Image-Pro Version 4.0. The measurement parameters were determined by averaging the number of n = 20 per sample using the diameter equivalent of the projected area circle.

[Spinnability/Fiber Breakage Frequency]

The frequency of fiber breakage relative to the solid content of the spinning solution was measured in terms of the number of fiber breakages/t.

[Preparation of the Slowly Water-Soluble Glass Containing a Group IB and/or Group 2B Element]

First, 24 mol% of S1O2, 52 mol% of B2O3, 10 mol% of Na20, 10 mol% of T1O2, and 4 mol% of Ag _å 0 were mixed together and melted at 800°C to 1300°C. After cooling, the resulting glass was pulverized, classified to an average primary particle size of 10 pm or less, and wet-milled to an average primary particle diameter of 0.8 pm to obtain a white powder. This was slowly water-soluble silver glass 1.

Also, 48 mol% of P2O5, 48 mol% of MgO, and 4 mol% of Ag _å 0 were mixed together and melted at 800°C to 1300°C. After cooling, the resulting glass was pulverized, classified to an average primary particle size of 10 pm or less, and wet-milled to an average primary particle diameter of 0.8 pm to obtain a white powder. This was slowly water-soluble silver glass 2.

[Preparation of Knitted Fabric for Evaluation Purposes]

First, a 22-dtex polyurethane elastic fiber was stretched by a factor of three, and this was covered at a twist number of 800 T/m with a polyamide-processed fiber (Quup 33 decitex/26 filament from Toray Industries) serving as a sheath fiber to produce S-twisted and Z-twisted single covering yarns (SCY).

The S-twisted SCY was supplied to yarn feeders 1 and 3 and the Z-twisted SCY was supplied to yarn feeders 2 and 4 of a pantyhose knitting machine (from Lonati, 400 stitches) at a knitting tension of 1.0 g to produce a knitted fabric. The polyurethane elastic fiber content of the knitted fabric was 16%.

Next, the following steps were performed to dye the knitted fabric and obtain a knitted fabric for tights.

(1) Preset: A vacuum dryer was used at 90°C for 10 minutes.

(2) Dyeing: 2.0 owf% of Lanaset (registered trademark) Black B dye from Ciba Specialty Chemicals was used at 90°C for 60 minutes to dye the knitted fabric black. The pH adjustments during the dyeing process were made using acetic acid and ammonium sulfate.

(3) Finally, softening was performed, and finishing was performed via the setting process (using a pantyhose set machine, setting: 115°C x 10 seconds, drying: 120°C x 30 seconds).

[Washing Method]

This was performed in compliance with the Washing Method Manual of the Japan Textile Evaluation Technology Council (Appendix 1, Washing Method 103 in JIS L0217: 2020).

Using the household electric washing machine specified in Washing Method 103, 40 ml of the JAFET standard detergent (from the Japan Textile Evaluation Technology Council) was dissolved in 30 liters of water at 40°C to produce a liquid washing detergent, and a 1 kg laundry sample was added to this liquid washing detergent. The laundry sample was washed using a process in which a single cycle consisted of washing for five minutes, dewatering, rinsing for two minutes, dewatering, rinsing for two minutes, and dewatering.

[Antibacterial Properties]

An antibacterial test was carried out in accordance with the antibacterial test procedure (JIS L1902: 2015, bacterial solution absorption method) specified by the Japan Textile Evaluation Technology Council. The antibacterial activity value was calculated and the antibacterial activity evaluated using X as the viable cell count in an untreated test sample after culturing for 18 hours and Y as the viable cell count in a treated test sample after culturing for 18 hours. The measured value was the average value of n = 3. According to the Japan Textile Evaluation Technology Council, antibacterial activity is effective when the antibacterial activity value for Staphylococcus aureus is 2.2 or higher.

[Strength, Stress Relaxation Rate, Permanent Strain Rate, and Elasticity of the Polyurethane Elastic Fibers]

In order to measure the strength, stress relaxation rate, permanent strain rate, and elasticity of the polyurethane elastic fibers, tensile testing was carried out on a sample fiber using an Instron 4502 tensile tester.

These are defined as follows.

First, a 5 cm (LI) sample was elongated by 300% five times at a tensile rate of 50 cm/min. The stress during the fifth time was defined as (Gl). The sample length was then held at an elongation of 300% for 30 seconds. The stress after holding 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).

These characteristics are expressed by the following equations.

Breaking strength [cN] = (G3)

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

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

Elasticity [%] = 100 x ((L3)-(L1))/(L1)

The tensile testing was performed three times and the average values were used.

[Example 1]

PTMG having a molecular weight of 1,800 and MDI were reacted at a molar ratio of 1: 1.58 at 90°C for two hours to obtain an isocyanate-terminated prepolymer, and 35% by mass of the isocyanate-terminated prepolymer was dissolved in DMAc to obtain a prepolymer solution. Ethylenediamine and 1,2-propanediamine serving as chain extenders and diethylamine serving as a chain terminator were mixed together at a mass ratio of 5: 1: 1, and 35% by mass of the mixture was dissolved in DMAc to obtain an amine solution.

The prepolymer solution and the amine solution were mixed together while stirring at an isocyanate terminal group to amine terminal group molar ratio of 1: 1.02 to prepare a DMAC solution (35% by mass) of a polyurethane urea polymer. Next, a t-butyldiethanolamine antioxidant with methylene-bis-(4-cyclohexyl isocyanate) (DuPont Metachlor (registered trademark) 2462) was mixed with a condensation polymer of p-cresol and divinylbenzene (DuPont Metachlor (registered trademark) 2390) at a ratio (mass ratio) of 2:1 to prepare an antioxidant DMAc solution (concentration 35% by mass). Then, 96 parts by mass of the polyurethane urea polymer DMAc solution and 4 parts by mass of the antioxidant solution were mixed together to obtain polymer solution Al. Next, slowly water-soluble silver glass 1 serving as the slowly water-soluble glass containing a Group IB and/or Group 2B element, and a polyoxyethylene alkyl ether (Ionet MO from Sanyo Chemical Industries) serving as the nonionic surfactant were dispersed in DMAc to obtain dispersion solution B1 (35% by mass). Then, polymer solutions Al and B1 were uniformly mixed together at 97% by mass and 2% by mass to prepare spinning solution Dl. This was dry-spun at a speed of 720 m/min with a speed ratio of 1.3 between the Godet roller and the winder to obtain 200 g of spooled 22-decitex/2-filament polyurethane elastic yarn containing 2% by mass of the slowly water-soluble glass antibacterial agent and 0.1% by mass of the nonionic surfactant.

The spinnability, NOx yellowing resistance, and elasticity characteristics of the resulting polyurethane fiber were measured. A knitted fabric was created for evaluation purposes, and the antibacterial properties of the knitted fabric were measured. The results of these evaluations are shown in Table 1 and Table 2.

[Example 2] to [Example 8]

A polyurethane elastic fiber was obtained from a composition composed of an antibacterial component and a surfactant component shown in Table 1 using the same method as that of Example 1. The spinnability, NOx yellowing resistance, and elasticity characteristics of the resulting polyurethane fiber were measured. A knitted fabric was created for evaluation purposes, and the antibacterial properties of the knitted fabric were measured. The results of these evaluations are shown in Table 1 and Table 2.

[Example 9] and [Example 10]

A polyurethane elastic fiber was obtained from a composition composed of an antibacterial component, a surfactant component, and a quaternary ammonium salt-based antibacterial agent shown in Table 1 using the same method as that of Example 1. After mixing polymer solution A1 with a dispersion solution containing slowly water-soluble silver glass 1 and the nonionic surfactant, the quaternary ammonium salt-based antibacterial agent was added and dissolved to obtain a spinning solution. The spinnability, NOx yellowing resistance, and elasticity characteristics of the resulting polyurethane fiber were measured. A knitted fabric was created for evaluation purposes, and the antibacterial properties of the knitted fabric were measured. The results of these evaluations are shown in Table 1 and Table 2.

[Comparative Example 1]

Polymer solution A1 was dry-spun in the same manner as in Example 1 to obtain 200 g of wound 22 decitex, double-filament polyurethane yarn. The spinnability, NOx yellowing resistance, and elasticity characteristics of the resulting polyurethane fiber were measured. A knitted fabric was created for evaluation purposes, and the antibacterial properties of the knitted fabric were measured. The results of these evaluations are shown in Table 1 and Table 2.

[Comparative Example 2] to [Comparative Example 8]

A polyurethane elastic fiber was obtained from a composition composed of an antibacterial component and a surfactant component shown in Table 1 using the same method as that of Example 1. The spinnability, NOx yellowing resistance, and elasticity characteristics of the resulting polyurethane fiber were measured. A knitted fabric was created for evaluation purposes, and the antibacterial properties of the knitted fabric were measured. The results of these evaluations are shown in Table 1 and Table 2.

[Table 1] ,

Table 1 contd. (a)

Table 1 contd. (c)

[Table 2]