JP7814964B2 - Polyurethane elastic yarn and its manufacturing method - Google Patents

Description

The present invention relates to polyurethane elastic yarns that have excellent antibacterial properties and excellent colorfastness, and to polyurethane elastic yarns suitable for producing antibacterial fabrics and methods for producing the same.

Due to their excellent elasticity, elastic fibers are widely used in stretchable clothing such as legwear, underwear, and sportswear, sanitary products such as disposable diapers and sanitary napkins, and industrial materials.

In recent years, with the demand for more comfortable living environments, so-called "antibacterial products" such as antibacterial paint, antibacterial film/sheet, antibacterial filament, antibacterial toiletries, antibacterial kitchenware, antibacterial stationery, antibacterial sand, antibacterial tissue, antibacterial fibers, and antibacterial cosmetics have become widely available.

The antibacterial agents used in these products are often inorganic, especially silver-based antibacterial agents.

The above inorganic antibacterial agents have superior weather resistance and chemical resistance, and low acute oral toxicity compared to organic antibacterial agents. In addition, their heat resistance is significantly higher than that of organic antibacterial agents, so they have come to be added to synthetic resins and used in a wide range of fields.

The metal ions that make up the inorganic antibacterial agents include silver, mercury, copper, zinc, and tin, with silver ions and copper ions being particularly prominent. Supporting these ions on porous materials such as glass, zeolite, silica gel, silicates, whiskers, alumina, and ceramics can provide excellent antibacterial effects. Many techniques for applying these to fibers have been proposed (Patent Documents 1 to 3).

However, when inorganic antibacterial agents are added to synthetic resins and then molded, problems can easily arise that significantly reduce the value of the product due to defects caused by gelation of the synthetic resin or changes in molecular weight due to the crosslinking and catalytic action of the metals contained in the inorganic antibacterial agents, thermal discoloration during molding, discoloration due to NOx gases to which the molded product is exposed, and discoloration due to light irradiating the molded product.

In response, technologies have been proposed to prevent discoloration of antibacterial resins containing inorganic antibacterial agents (Patent Document 4). However, while these technologies provide a certain level of antibacterial performance, they are prone to significant discoloration due to the environment and the passage of time, making it difficult to say that they have adequately resolved the problem.

Japanese Patent Application Publication No. 5-339810 Japanese Patent Application Publication No. 6-93565 JP 2017-40007 A Patent No. 4485871

The objective of the present invention is to provide polyurethane elastic yarn that has excellent antibacterial properties and excellent colorfastness, and a method for manufacturing the same.

In order to solve the above problems, the present invention employs any of the following means.
(1) A polyurethane elastic yarn whose main constituent is a polyurethane whose main starting materials are a polymer diol and a diisocyanate, and which contains (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and (b) a nonionic surfactant.
(2) The polyurethane elastic yarn according to (1) above, in which the content of (a) is 0.1% by mass or more and 30% by mass or less.
(3) The polyurethane elastic yarn according to (1) or (2) above, wherein the average primary particle diameter of (a) is 3.0 μm or less.
(4) A polyurethane elastic yarn according to any one of (1) to (3) above, wherein (a) is a glass having a slightly water solubility containing silver and/or a glass having a slightly water solubility containing copper.
(5) The polyurethane elastic yarn according to any one of (1) to (4), wherein (b) is polyoxyethylene alkyl ether.
(6) The polyurethane elastic yarn according to any one of (1) to (5) above, which contains a quaternary ammonium salt-based antibacterial agent.
(7) A method for producing an elastic polyurethane yarn, comprising: mixing (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element with a spinning dope containing polyurethane having a polymer diol and a diisocyanate as the main starting materials; mixing a nonionic surfactant in an amount of 0.01% by mass or more and 20% by mass or less relative to the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element; and dry-spinning the spinning dope.
(8) A method for producing a polyurethane elastic yarn according to (7) above, in which (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element is mixed as a dispersion into a spinning dope containing polyurethane whose main starting materials are a polymer diol and a diisocyanate.
(9) The method for producing polyurethane elastic yarn according to (7) or (8) above, wherein (a) the Group 1B element and/or Group 2B element is silver and/or copper.
(10) A method for producing polyurethane elastic yarn according to any one of (7) to (9) above, wherein (b) is polyoxyethylene alkyl ether.

According to the present invention, an elastic polyurethane yarn can be obtained, which is made of polyurethane whose main components are polymer diol and diisocyanate, and which contains (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant, and which has excellent antibacterial properties, colorfastness, and stretchability. Therefore, fabrics made using such polyurethane elastic yarn have excellent antibacterial properties, colorfastness, and stretchability.

The present invention will be described in more detail below.

First, we will discuss the polyurethane used as the main component in the polyurethane elastic yarn of the present invention. Here, the main component is a component that is contained in the polyurethane elastic yarn in an amount of more than 50% by mass.

The polyurethane used in the present invention may be any polyurethane having a structure derived from polymer diol and diisocyanate as the primary starting materials, and is not particularly limited. Here, "using polymer diol and diisocyanate as starting materials" means that the resulting polyurethane polymer has a structure derived from each of these components. In other words, this specification specifies the structure of a polyurethane polymer obtained from polymer diol and diisocyanate as starting materials; it does not specify the raw materials themselves, as the same structure may be formed from different raw materials. Furthermore, the synthesis method is not particularly limited. For example, it may be a polyurethane urea composed of a polymer diol, diisocyanate, and a low-molecular-weight diamine as a chain extender, or a polyurethane urethane composed of a polymer diol, diisocyanate, and a low-molecular-weight diol as a chain extender. It may also be a polyurethane urea using a compound having a hydroxyl group and an amino group in the molecule as a chain extender. It is also preferable to use trifunctional or higher polyfunctional glycols, isocyanates, etc., as long as they do not interfere with the effects of the present invention. Here, a polyurethane having a structure based primarily on polymer diol and diisocyanate refers to a starting material containing more than 50% by weight of diisocyanate among the isocyanate compounds, and more than 50% by weight of the components that react with the isocyanate compounds (polymer diol, low molecular weight diamine, low molecular weight diol, compound containing hydroxyl and amino groups in the molecule, polyfunctional glycol, etc.) in the starting material. Note that when calculating the mass ratio, the calculation is performed assuming that the above components are used as starting materials, regardless of the actual raw materials used. Furthermore, among diol compounds, low molecular weight diol refers to one with a molecular weight of less than 500, and one with a molecular weight of 500 or more is called a polymer diol (the same applies to diamine compounds).

Preferred polymer diols include polyether-based, polyester-based diols, and polycarbonate diols. In particular, polyether-based diols are preferred from the perspective of imparting flexibility and elongation to the yarn.

Preferred examples of polyether diols include polyethylene oxide, polyethylene glycol, polyethylene glycol derivatives, polypropylene glycol, polytetramethylene ether glycol (hereinafter abbreviated as PTMG), modified PTMG which is a copolymer of tetrahydrofuran (THF) and 3-methyltetrahydrofuran, modified PTMG which is a copolymer of tetrahydrofuran (THF) and 2-methyltetrahydrofuran, modified PTMG which is a copolymer of THF and 2,3-dimethylTHF, polyols having side chains on both sides as disclosed in Japanese Patent No. 2615131, and random copolymers in which THF and ethylene oxide and/or propylene oxide are irregularly arranged. These polyether diols may be used alone or in combination or copolymerized with two or more.

In addition, from the perspective of achieving abrasion resistance and light resistance as polyurethane elastic yarns, polyester diols such as butylene adipate, polycaprolactone diol, and polyester polyols with side chains as disclosed in JP-A-61-26612, and polycarbonate diols as disclosed in JP-B-2-289516 are preferably used.

Furthermore, these polymer diols may be used alone, or two or more types may be mixed or copolymerized and used.

From the perspective of obtaining elongation, strength, heat resistance, etc. when made into a yarn, the molecular weight of the polymer diol is preferably a number average molecular weight of 1,000 or more and 8,000 or less, and more preferably 1,500 or more and 6,000 or less. By using a polyol with a molecular weight within this range, it is possible to easily obtain an elastic yarn with excellent elongation, strength, elastic recovery, and heat resistance.

Next, aromatic diisocyanates such as diphenylmethane diisocyanate (hereinafter abbreviated as MDI), tolylene diisocyanate, 1,4-diisocyanatobenzene, xylylene diisocyanate, and 2,6-naphthalene diisocyanate are particularly suitable for synthesizing polyurethanes with high heat resistance and strength. Furthermore, preferred 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-1,5-naphthalene diisocyanate. Alicyclic diisocyanates are particularly effective in preventing yellowing of polyurethane elastic yarns. These diisocyanates may be used alone or in combination.

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

Preferred low-molecular-weight diamines include, for example, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, hexamethylenediamine, p-phenylenediamine, p-xylylenediamine, m-xylylenediamine, p,p'-methylenedianiline, 1,3-cyclohexyldiamine, hexahydrometaphenylenediamine, 2-methylpentamethylenediamine, and bis(4-aminophenyl)phosphine oxide. It is preferable to use one or more of these. Ethylenediamine is particularly preferred. The use of ethylenediamine makes it easy to obtain yarn with excellent elongation, elastic recovery, and heat resistance. A triamine compound capable of forming a crosslinked structure, such as diethylenetriamine, may be added to these chain extenders to the extent that the effect is not lost.

Typical low-molecular-weight diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, bishydroxyethoxybenzene, bishydroxyethylene terephthalate, and 1-methyl-1,2-ethanediol. It is preferable to use one or more of these. Ethylene glycol, 1,3-propanediol, and 1,4-butanediol are particularly preferred. Using these diol-extended polyurethanes increases their heat resistance, and allows for the production of stronger yarns.

In addition, in the present invention, the molecular weight of the polyurethane is preferably in the range of 30,000 or more and 150,000 or less in number average molecular weight, in order to obtain polyurethane elastic yarn with high durability and strength. The molecular weight is measured by GPC and converted into polystyrene.

It is also preferable to use one or more terminal blocking agents in combination with polyurethane. Preferred terminal blocking agents include monoamines such as dimethylamine, diisopropylamine, ethylmethylamine, diethylamine, methylpropylamine, isopropylmethylamine, diisopropylamine, butylmethylamine, isobutylmethylamine, isopentylmethylamine, dibutylamine, and diamylamine; monools such as ethanol, propanol, butanol, isopropanol, allyl alcohol, and cyclopentanol; and monoisocyanates such as phenyl isocyanate.

In the present invention, by incorporating (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant into a polyurethane elastic yarn made of polyurethane having the basic structure described above, it is possible to impart excellent antibacterial properties.

_The term "slightly water-soluble glass" generally refers to a water-insoluble silicate glass, i.e., a glass that dissolves slowly in water and is produced by blending _SiO2 , the main raw material, with 30% by mass or more of _{P2O5 and} /or _B2O3 in total. The slightly water-soluble glass used in the present invention is sufficient as long as it can retain the (a) Group 1B element and/or Group 2B element. It may be not only a typical slightly water-soluble glass primarily made of _SiO2 , but also a glass primarily made of _{P2O5 and} /or _{B2O3 ,} which can be vitrified independently, or a glass that does not contain _SiO2 at all. If the slightly water-soluble glass of the present invention contains less than 30% by mass of _{P2O5 and} /or _B2O3 , the elution of (a) Group 1B element and/or Group 2B element ions will be poor during the aqueous processing step of _the polyurethane elastic yarn, such as the dyeing step, resulting in insufficient antibacterial effect.

In the present invention, the (a) Group 1B element and/or Group 2B element contained in the slightly water-soluble glass is preferably blended as a raw material in the form of an oxide. Examples of oxides of the (a) Group 1B element and/or Group 2B element include AgO, _Ag2O , _{Ag2O3 ,} CuO, _Cu2O , ZnO, and _Au2O3 . From the standpoint of antibacterial properties, the lower the oxidation number of the (a) Group 1B element and/or Group 2B element, as long as the oxidation number is stable as a substance, is preferable, and _Ag2O and _CuO are particularly preferable. It is preferable that such oxides of the (a) Group 1B element and/or Group 2B element be blended in a total amount of 1 mass% or more, based on the raw material, into the phosphate-based and/or boric acid-based slightly water-soluble glass powder.

This (a) phosphate-based and/or boric acid-based glass containing Group 1B and/or Group 2B elements can be used to produce polyurethane elastic threads with antibacterial properties by various methods. These (a) glass containing Group 1B and/or Group 2B elements may be used alone or in combination. The method for producing the glass containing Group 1B and/or Group 2B elements is not particularly limited, and melt-quenching and sol-gel methods are preferred. In addition to the aforementioned components, trace components such as SrO, BaO, TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Cs ₂ O, Rb ₂ O, TeO _{2 , BeO, GeO 2} , Bi ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ , WO ₃ , MoO ₃ , and Fe ₂ O ₃ can also be added during _the production of the glass to form a glass solid solution. Furthermore, F, Cl, SO ₃ , Sb ₂ O ₃ , SnO ₂ , Ce, or the like may be added as a fining agent.

(a) The content of the slightly water-soluble glass containing a Group 1B element and/or a Group 2B element is preferably in the range of 0.1% by mass or more and 30% by mass or less, based on the total mass of the polyurethane elastic yarn. If the content of the slightly water-soluble glass containing a Group 1B element and/or a Group 2B element is less than 0.1% by mass, it may be difficult to obtain sufficient antibacterial properties when made into a fabric. A content of 0.5% by mass or more is more preferable. On the other hand, a content of more than 30% by mass may be undesirable in terms of deterioration of stretch properties and cost. A content of 10% by mass or less is preferable, and a content of 5.0% by mass or less is even more preferable. Considering the balance between antibacterial properties, physical properties, and cost, a range of 1.0% by mass or more and 5.0% by mass or less is particularly preferable.

In addition, in the present invention, the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element preferably has an average primary particle diameter of 3.0 μm or less, more preferably 1.5 μm or less, from the viewpoint of preventing clogging of the spinning dope in the spinneret. Furthermore, from the viewpoint of dispersibility, if the average primary particle diameter is less than 0.05 μm, the cohesion increases, making it difficult to uniformly mix the particles in the spinning dope. Therefore, an average primary particle diameter of 0.05 μm or more is preferred, more preferably 0.15 μm or more. The average primary particle diameter was measured using an electron microscope. For example, primary particles located between two parallel lines in a certain direction sandwiching a primary particle in a field of view of several tens of thousands of times were image-processed to generate circles equivalent to the projected area of the primary particles. 20 diameters were measured at random, and the top 5% (maximum value) and bottom 5% (minimum value) were removed based on the number of particles, and the average of the remaining 90% (18 values) was calculated. Furthermore, the particle size distribution, calculated by dividing the average primary particle size by the most frequent particle size (mode diameter), is preferably 0.5 to 1.5, and more preferably 0.8 to 1.2. Furthermore, it is preferable that the maximum particle size is distributed within 2.0 times the average primary particle size, and more preferably within 1.5 times.

In the present invention, it is preferable that (a) the slightly water-soluble glass containing a Group 1B element and/or a Group 2B element is uniformly distributed throughout the polyurethane. While it is known that various surfactants can be used as dispersants to achieve this, we have discovered that the use of a nonionic surfactant is sufficient to uniformly disperse (a) the slightly water-soluble glass containing a Group 1B element and/or a Group 2B element throughout the polyurethane, thereby obtaining polyurethane elastic yarn with excellent spinnability, antibacterial properties, colorfastness, and stretchability. We have also discovered that the use of a nonionic surfactant has a synergistic effect, particularly on antibacterial properties. On the other hand, ionic surfactants such as anionic surfactants, cationic surfactants, and anionic-cationic amphoteric surfactants may not exhibit antibacterial properties after undergoing aqueous processing steps, such as dyeing, which are essential for fabrics used in clothing.

Examples of nonionic surfactants used in the present invention include polyoxyethylene alkyl ethers, alkyl monoglyceryl ethers, polyoxyethylene alkylamines, fatty acid sorbitan esters, and fatty acid diethanolamides. Of these, the hydrophilic portion of the surfactant is preferably an ether type, and is preferably at least one of ethylene oxide polymers, propylene oxide polymers, and copolymers of ethylene oxide and propylene oxide. By incorporating at least one of terminally modified derivatives of ethylene oxide polymers, terminally modified derivatives of propylene oxide polymers, and terminally modified derivatives of copolymers of ethylene oxide and propylene oxide as a nonionic surfactant, it is possible to improve spinnability while also achieving good antibacterial properties. The so-called hydrophobic portion of the surfactant (Hydrophob) is the aforementioned terminally modified structure, and is preferably an alkyl group, a phenyl group, or a styrenated phenyl group. Specific examples of nonionic surfactants include polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene ethylphenol ether, polyoxyethylene propylphenol ether, polyoxyethylene styrenated phenyl ether, and polyoxyethylene sorbitol tetraoleate. More preferred are polyoxyethylene styrenated phenyl ethers, including polyoxyethylene oxypropylene tristyrenated phenyl ether, polyoxyethylene oxypropylene distyrenated phenyl ether, polyoxyethylene oxypropylene monostyrenated phenyl ether, polyoxyethylene oxypropylene-2,4,6-tris(α,α-dimethylbenzyl)phenyl ether, polyoxyethylene oxypropylene-2,4-bis(α,α-dimethylbenzyl)phenyl ether, polyoxyethylene oxypropylene-2-mono(α,α-dimethylbenzyl)phenyl ether, and polyoxyethylene oxypropylene-4-mono(α,α-dimethylbenzyl)phenyl ether. Most preferred are mixtures of these with a distribution of added moles of styrene groups.

In the present invention, it is preferable to use a quaternary ammonium salt antibacterial agent in combination. Controlling skin sensitization at an appropriate antibacterial level is particularly important for textile structures used in clothing, medical fabrics, and hygiene products. While slightly water-soluble glass containing Group 1B and/or Group 2B elements is completely inorganic, organic quaternary ammonium salt antibacterial agents tend to distribute on the surface of polyurethane elastic yarns, where quaternary ammonium elution proceeds more rapidly. This makes it easy to control the initial antibacterial performance immediately after manufacturing or various processing steps such as dyeing. On the other hand, since the elution of Group 1B and/or Group 2B elements from slightly water-soluble glass containing Group 1B and/or Group 2B elements proceeds more slowly, adjusting the amount added and particle size, etc., makes it easy to maintain the required level of antibacterial performance even after repeated washing or long-term aging. In this way, by incorporating antibacterial agents with different elution rates of antibacterial components into polyurethane elastic yarns, it is possible to design an optimal level of antibacterial performance from the initial state to long-term aging. When a quaternary ammonium salt-based antibacterial agent is used in combination, the antibacterial activity varies depending on the chain length of the alkyl group in the ammonium ion. Stronger antibacterial activity is desirable. However, from the viewpoints of suppressing thermal decomposition due to heat exposure during the production of polyurethane elastic yarns and suppressing the ionic nature of the (a) Group 1B element and/or Group 2B element-containing glass with low water solubility, which inhibits the elution of the (a) Group 1B element and/or Group 2B element, it is preferable to select a chain type such as an alkyl group, e.g., an alkyl group with a large chain length, i.e., a large number of carbon atoms. From this viewpoint, particularly preferred ammonium ions include didecyldimethylammonium ion and oleyltrimethylammonium ion. It is also preferable to consider the counter anion constituting the quaternary ammonium salt. These counter anions are typically provided by inorganic salts such as chlorides, bromides, and iodides, or organic salts such as carboxylates, sulfonates, and phosphates. Of these, carboxylates and sulfonates are preferred from the viewpoints of stability, such as discoloration and heat resistance, and improved breaking strength and elongation, with carboxylates being most preferred.

Specific examples of salts having the above structure include didecyldimethylammonium carboxylates such as didecyldimethylammonium adipate, didecyldimethylammonium gluconate, and didecyldimethylammonium propionate; oleyltrimethylammonium carboxylates such as oleyltrimethylammonium adipate and oleyltrimethylammonium gluconate; and sulfonates such as didecyldimethylammonium trifluoride methylsulfonate, di-n-decyldimethylammonium trifluoromethanesulfonate, di-n-decyldimethylammonium pentafluoroethanesulfonate, n-hexadecyltrimethylammonium trifluoromethanesulfonate, and benzyldimethyl coconut oil alkyl ammonium pentafluoroethanesulfonate.

From the viewpoint of exhibiting antibacterial properties and maintaining a balance between discoloration and stretch properties, the quaternary ammonium salt antibacterial agent is preferably contained in an amount ranging from 0.1% by mass to 5% by mass of the total polyurethane elastic yarn. The polyurethane elastic yarn of the present invention may also contain various stabilizers, pigments, etc. For example, it is preferable that light fasteners, antioxidants, etc. include hindered phenol-based agents such as BHT and Sumitomo Chemical Co., Ltd.'s "Sumilizer" (registered trademark) GA-80, various benzotriazole-based and benzophenone-based agents such as Ciba-Geigy's "Tinuvin" (registered trademark), phosphorus-based agents such as Sumitomo Chemical Co., Ltd.'s "Sumilizer" (registered trademark) P-16, various hindered amine-based agents, various pigments such as iron oxide and titanium oxide, inorganic substances such as zinc oxide, cerium oxide, magnesium oxide, calcium carbonate, and carbon black, fluorine-based or silicone-based resin powder, metal soap such as magnesium stearate, lubricants such as silicone and mineral oil, and various antistatic agents such as cerium oxide, betaine, and phosphate-based, and it is also preferable that these are reacted with the polymer. To further enhance durability, particularly against light and various nitrogen oxides, it is also preferable to use a nitrogen oxide scavenger such as HN-150 manufactured by Nippon Hydrazine Co., Ltd., a thermal oxidation stabilizer such as Sumilizer (registered trademark) GA-80 manufactured by Sumitomo Chemical Co., Ltd., or a light stabilizer such as Sumisorb (registered trademark) 300#622 manufactured by Sumitomo Chemical Co., Ltd.

Next, we will explain in detail the method for producing the polyurethane elastic yarn of the present invention.

In the present invention, polymer diol and diisocyanate are used as the main starting materials, and the polyurethane spinning solution obtained therefrom is dry-spun with (a) a slightly water-soluble glass containing Group 1B and/or Group 2B elements and a nonionic surfactant. When preparing the polyurethane spinning solution by mixing (a) a slightly water-soluble glass containing Group 1B and/or Group 2B elements and a nonionic surfactant, the nonionic surfactant is mixed in an amount ranging from 0.01 to 20 parts by mass per 100 parts by mass of (a) the slightly water-soluble glass containing Group 1B and/or Group 2B elements. More preferably, in the step of finely powdering (a) the slightly water-soluble glass containing Group 1B and/or Group 2B elements, the nonionic surfactant is premixed with the fine powder, and the fine powder is coated with the nonionic surfactant. The polyurethane solution and the polyurethane, which is the solute of the solution, may be produced by either melt polymerization or solution polymerization, or by other methods. However, solution polymerization is more preferable. With solution polymerization, there is less generation of foreign matter such as gel in the polyurethane, spinning is easier, and it is easier to obtain low-fineness polyurethane elastic yarn. Furthermore, solution polymerization has the advantage of eliminating the need for the step of creating a solution.

Polyurethanes that are particularly suitable for the present invention include those synthesized using PTMG with a molecular weight of 1,500 to 6,000 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.

Polyurethane can be obtained by synthesizing the above raw materials in a solvent such as dimethylacetamide (DMAc), dimethyl sulfoxide (DMF), dimethyl sulfoxide (DMSO), or n-methylpyrrolidinone (NMP), or a solvent containing these as its main components. Particularly suitable methods include the one-shot method, in which the raw materials are added to and dissolved in such a solvent, and then heated to an appropriate temperature to react to form polyurethane. Another method is to first melt-react a polymer diol and a diisocyanate, then dissolve the reactant in a solvent and react it with the chain extender described above to form polyurethane.

When a diol is used as the chain extender, it is preferable to adjust the high-temperature melting point of the polyurethane to a range of 200°C or higher and 260°C or lower in order to obtain a product with excellent heat resistance. A typical method for achieving this is to control the types and ratios of polymer diol, MDI, and diol. When the molecular weight of the polymer diol is low, a polyurethane with a high high-temperature melting point can be obtained by increasing the proportion of MDI relatively. Similarly, when the molecular weight of the diol is low, a polyurethane with a high high-temperature melting point can be obtained by decreasing the proportion of polymer diol relatively.

When the molecular weight of the polymer diol is 1,800 or more, in order to achieve a high-temperature melting point of 200°C or higher, it is preferable to carry out polymerization at a ratio of (number of moles of MDI)/(number of moles of polymer diol) of 1.5 or more.

In addition, when synthesizing such polyurethanes, it is also preferable to use one or a mixture of two or more catalysts such as amine catalysts or organometallic catalysts.

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'-tetramethyl-1,3-propanediamine, N,N,N',N'-tetramethylhexanediamine, bis-2-dimethylaminoethyl ether, N,N,N',N',N'-pentamethyldiethylenetriamine, tetramethylguanidine, and triethylene Examples include diamine, 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.

Other organometallic catalysts include tin octoate, dibutyltin dilaurate, and lead dibutyl octoate.

The polyurethane concentration in the polyurethane solution obtained in this manner is generally preferably in the range of 30% by mass or more and 80% by mass or less.

In the present invention, (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant are added to the polyurethane solution. Any method can be used to add (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant to the polyurethane solution. Typical methods include using a static mixer, stirring, a homomixer, and a twin-screw extruder.

In the present invention, in order to improve antibacterial properties, it is preferable to incorporate (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element into the polyurethane elastic yarn in a range of 0.5% by mass to 10% by mass. To achieve this, it is necessary to evenly disperse (a) a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element in a polyurethane spinning dope prior to spinning in a range of 0.5% by mass to 10% by mass. Preferably, the above-mentioned (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant are added to a polyurethane spinning dope containing N,N-dimethylformamide, N,N-dimethylacetamide, or the like as a solvent, and the mixture is stirred and mixed to disperse the glass evenly. Specifically, it is preferable to first disperse the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant in a solvent such as N,N-dimethylformamide or N,N-dimethylacetamide to prepare a (a) slightly water-soluble glass dispersion containing a Group 1B element and/or a Group 2B element, and then mix this dispersion with the polyurethane spinning dope. Here, the solvent for the (a) slightly water-soluble glass dispersion containing a Group 1B element and/or a Group 2B element to be added is preferably the same as that for the polyurethane solution, in order to ensure uniform addition to the polyurethane solution. Furthermore, when adding the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element to the polyurethane solution, the aforementioned agents such as light stabilizers and antioxidants, as well as pigments, may also be added simultaneously. Furthermore, in order to achieve antibacterial properties, it is preferable to prepare a dispersion of the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant in advance, and then mix this dispersion with the polyurethane spinning dope.

In addition, in the present invention, it is also preferable to add a quaternary ammonium salt antibacterial agent to enhance antibacterial properties against various bacteria. To do so, a quaternary ammonium salt antibacterial agent is added to the polyurethane spinning dope before spinning, and then spinning is performed. The quaternary ammonium salt antibacterial agent can be added to the spinning dope by mixing it alone with the spinning dope, or by pre-mixing it with the (a) slightly water-soluble glass containing a Group 1B element and/or a Group 2B element and a nonionic surfactant dispersion. It is more preferable to pre-mix a nonionic surfactant and a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element to form a dispersion, and then mix the quaternary ammonium salt antibacterial agent into the polyurethane spinning dope. The most preferred method for incorporating a quaternary ammonium salt antibacterial agent into the spinning dope is to mix the quaternary ammonium salt antibacterial agent alone with the spinning dope, independently of the dispersion in which a nonionic surfactant and a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element are premixed.

The polyurethane elastic yarn of the present invention can be obtained by dry spinning, wet spinning, or melt spinning the spinning dope prepared as described above, and then winding it up. Of these, dry spinning is preferred from the viewpoint of enabling stable spinning of yarns of all finenesses, from thin to thick.

The fineness and cross-sectional shape of the polyurethane elastic yarn of the present invention are not particularly limited. For example, the cross-sectional shape of the yarn may be circular or flat.

The dry spinning method is not particularly limited, and spinning conditions can be appropriately selected to suit the desired properties and spinning equipment.

For example, the permanent set rate and stress relaxation of the polyurethane elastic yarn of the present invention are particularly susceptible to the influence of the speed ratio between the godet roller and the winder, and therefore it is preferable to determine these appropriately depending on the intended use of the yarn. In other words, from the perspective of obtaining polyurethane elastic yarn with the desired permanent set rate and stress relaxation, it is preferable to wind the yarn with a speed ratio between the godet roller and the winder in the range of 1.10 or more and 1.65 or less.

In addition, the spinning speed is preferably 250 m/min or more, from the viewpoint of improving the strength of the resulting polyurethane elastic yarn.

The present invention will be explained in more detail using examples, but is not limited to these.

[NOx yellowing resistance]
A sample card was prepared by winding 10 g of polyurethane elastic yarn onto a stainless steel plate. Using a Scott tester, this sample was exposed to a gas atmosphere containing _NO2 gas at a specified concentration (7 ppm) for 50 hours. Before and after this exposure treatment, the "b" color was measured using a color master (D25 DP-9000 signal processor), and the degree of yellowing was evaluated based on the difference "Δb" between before and after treatment. The measured values were calculated as the average of n = 3.

[Average primary particle diameter]
The inorganic particles were photographed using a field emission scanning electron microscope (FE-SEM) S-800 manufactured by Hitachi, Ltd., and analyzed using image processing software Image-Pro Version 4.0. The measurement parameter used was the projected area equivalent circle diameter, and the number average was determined for n = 20 particles per sample.

[Spinnability and frequency of yarn breakage]
The frequency of thread breakage per solid content of the spinning solution was measured in terms of the number of thread breakages/t.

[Preparation of Slightly Water-Soluble Glass Containing Group 1B Elements and/or Group 2B Elements]
₂₄ mol% SiO2, 52 mol% _B2O3 , 10 mol% _Na2O , 10 mol% _TiO2 , _and 4 mol% _Ag2O were mixed and melted at 800 to 1300°C. After cooling, the resulting glass was pulverized, and particles with an average primary particle size of 10 μm or less were classified. The resulting glass was then wet-milled to obtain a white powder with an average primary particle size of 0.8 μm. This was designated as slightly water-soluble silver glass 1.

Furthermore, 48 mol% _{of P2O5} , 48 mol% of MgO, and 4 mol% of _Ag2O were mixed and melted at 800 to 1300°C. After cooling, the resulting glass was pulverized, particles with an average primary particle size of 10 μm or less were classified, and then wet-milled to obtain a white powder with an average primary particle size of 0.8 μm. This was designated as slightly water-soluble silver glass 2.

[Creation of knitted fabric for antibacterial evaluation]
A 22 dtex polyurethane elastic yarn was stretched three times and covered with a polyamide processed yarn (trademark CUPE, manufactured by Toray Industries, Inc., 33 dtex, 26 filaments) as a sheath yarn at a twist rate of 800 T/m to produce S-twist and Z-twist single covered yarn (SCY).

Furthermore, the above-mentioned S-twisted SCY was fed to yarn feeders 1 and 3 of a pantyhose knitting machine (manufactured by Lonati, 400 needles), and the above-mentioned Z-twisted SCY was fed to yarn feeders 2 and 4 at a knitting tension of 1.0 g, and a knitted fabric was knitted. The content of polyurethane elastic yarn in the knitted fabric was 16%.

Next, the knitted fabric was dyed as follows to obtain a tights knitted fabric.
(1) Presetting: Using a vacuum dryer, 90°C x 10 minutes (2) Dyeing: The fabric was dyed black by processing at 90°C for 60 minutes using 2.0 owf% of the dye "Lanaset" (registered trademark) Black B manufactured by Chiba Specialty Chemicals Co., Ltd. The pH during dyeing was adjusted with acetic acid and ammonium sulfate.
(3) Finally, the fabric was subjected to a softening treatment and then finished through a setting process (using a pantyhose setting machine, setting at 115°C for 10 seconds, drying at 120°C for 30 seconds).

[Washing method]
The washing method was based on the washing method manual established by the New Functionality Evaluation Council for Textile Products (JIS L0217:2020, Appendix 1, Washing Method 103). Specifically, a household electric washing machine specified in Appendix 1, Washing Method 103 of JIS L0217:2020 was used, and 40 milliliters of JAFET standard detergent (manufactured by the New Functionality Evaluation Council for Textile Products) was dissolved in 30 liters of water at 40°C to prepare a washing solution. 1 kg of sample laundry was placed in this washing solution. The washing was performed by washing for 5 minutes, spin-drying, rinsing for 2 minutes, spin-drying, rinsing for 2 minutes, and spin-drying, which was counted as one cycle.

[Antibacterial]
The antibacterial test was conducted in accordance with the antibacterial testing procedure (JIS L1902:2015, bacterial solution absorption method) specified by the Japan Textile Evaluation Technology Council. The antibacterial activity value was calculated to evaluate the antibacterial power, with X representing the number of viable bacteria (units) after 18 hours of incubation in the untreated sample and Y representing the number of viable bacteria (units) after 18 hours of incubation in the test fabric. The measured values were calculated as the average of n = 3.
In addition, the Textile Evaluation Technology Council, a non-profit organization, considers a material to be "effective" against Staphylococcus aureus when its antibacterial activity value is 2.2 or higher.

[Strength, stress relaxation rate, permanent set rate, elongation of polyurethane elastic yarn]
The strength, stress relaxation rate, permanent set rate and elongation of the polyurethane elastic yarn were measured by subjecting the sample yarn to a tensile test using an Instron 4502 tensile tester.
These are defined below:
That is, a 5 cm (L1) sample was stretched 300% at a tensile speed of 50 cm/min, and this was repeated five times. The stress at the fifth stretch was defined as (G1). Next, the 300% stretch was maintained for 30 seconds. The stress after 30 seconds was defined as (G2). Next, the stretch was allowed to recover, and the length of the sample yarn when the stress returned to 0 was defined as (L2). The sample yarn was further stretched a sixth time until it broke. The stress at break was defined as (G3), and the length of the sample yarn at break was defined as (L3).
Hereinafter, the above characteristics are given by the following formula:
Strength [cN] = (G3)
Stress relaxation rate [%] = 100 × ((G1) - (G2)) / (G1)
Permanent distortion rate [%] = 100 x ((L2) - (L1)) / (L1)
Elongation [%] = 100×((L3)-(L1))/(L1)
The tensile test was carried out three times and the average value was calculated.

[Example 1]
PTMG with a molecular weight of 1,800 and MDI were reacted in a molar ratio of 1:1.58 at 90°C for 2 hours to form an isocyanate-terminated prepolymer, which was then dissolved in DMAc to prepare a 35% by mass prepolymer solution. Ethylenediamine and 1,2-propanediamine as chain extenders and diethylamine as a chain terminator were mixed in a mass ratio of 5:1:1, and the mixture was dissolved in DMAc to prepare a 35% by mass amine solution.

The prepolymer solution and amine solution were mixed with stirring to achieve a molar ratio of isocyanate end groups to amine end groups of 1:1.02 to prepare a 35% by mass polyurethane urea polymer solution in DMAC. Next, a polyurethane solution (DuPont's "Methachlor" (registered trademark) 2462) produced by the reaction of t-butyldiethanolamine and methylene-bis-(4-cyclohexylisocyanate) was mixed with a condensation polymer of p-cresol and divinylbenzene (DuPont's "Methachlor" (registered trademark) 2390) in a 2:1 ratio by mass to prepare a 35% by mass polyurethane urea polymer solution. 96 parts by mass of the polyurethane urea polymer solution in DMAC and 4 parts by mass of the antioxidant solution were mixed to prepare Polymer Solution A1. Next, a slightly water-soluble silver glass 1 containing a Group 1B element and/or a Group 2B element and a polyoxyethylene alkyl ether (Ionet MO manufactured by Sanyo Chemical Industries, Ltd.) as a nonionic surfactant were dispersed in DMAc using a homomixer to produce dispersion B1 (35% by mass). Polymer solutions A1 and B1 were then uniformly mixed at 97% by mass and 2% by mass to produce spinning solution D1. This solution was dry-spun at 720 m/min with a godet roller/winder speed ratio of 1.3 to produce a 200 g wound polyurethane yarn of 22 decitex, 2 filaments, containing 2% by mass of the slightly water-soluble glass antibacterial agent and 0.1% by mass of the nonionic surfactant.

The resulting polyurethane elastic yarn was evaluated for spinnability, NOx yellowing resistance, and stretchability. Furthermore, knitted fabrics for evaluation were prepared and antibacterial properties were measured. The results of these evaluations are shown in Tables 1 and 2.

[Example 2] to [Example 8]
Using the same method as in Example 1, polyurethane elastic yarn was obtained with a composition consisting of the antibacterial agent component and surfactant component shown in Table 1. The obtained polyurethane elastic yarn was measured for spinnability, NOx yellowing resistance, and stretch properties. Furthermore, knitted fabrics for evaluation were prepared and antibacterial properties were measured. The results of various evaluations are shown in Tables 1 and 2.

[Example 9] and [Example 10]
A polyurethane elastic yarn was obtained in the same manner as in Example 1, except that the composition consisted of the antibacterial agent component, surfactant component, and quaternary ammonium salt antibacterial agent shown in Table 1. The quaternary ammonium salt antibacterial agent was added and dissolved after mixing polymer solution A1 with a dispersion containing slightly water-soluble silver glass 1 and a nonionic surfactant to prepare a spinning solution. The resulting polyurethane elastic yarn was measured for spinnability, NOx yellowing resistance, and stretch properties. Furthermore, a knitted fabric for evaluation was prepared and its antibacterial properties were measured. The results of the various evaluations are shown in Tables 1 and 2.

[Comparative Example 1]
As in Example 1, polymer solution A1 was dry-spun to obtain a 200g wound body of 22 dtex, 2-filament polyurethane yarn. The resulting polyurethane elastic yarn was evaluated for spinnability, NOx yellowing resistance, and stretchability. Furthermore, a knitted fabric for evaluation was prepared, and its antibacterial properties were measured. The results of the various evaluations are shown in Tables 1 and 2.

[Comparative Example 2] to [Comparative Example 8]
Using the same method as in Example 1, polyurethane elastic yarn was obtained with a composition consisting of the antibacterial agent component and surfactant component shown in Table 1. The obtained polyurethane elastic yarn was measured for spinnability, NOx yellowing resistance, and stretch properties. Furthermore, knitted fabrics for evaluation were prepared and antibacterial properties were measured. The results of various evaluations are shown in Tables 1 and 2.

Claims (9)

A polyurethane elastic yarn whose main constituent is a polyurethane whose main starting materials are a polymer diol and a diisocyanate, and which contains (a) 0.5% by mass or more and 5.0% by mass or less of a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element, and (b) a nonionic surfactant. 2. The polyurethane elastic yarn according to claim 1 , wherein the average primary particle size of (a) is 3.0 μm or less. 3. The polyurethane elastic yarn according to claim 1, wherein (a) is a glass having a slightly water solubility containing silver and/or a glass having a slightly water solubility containing copper. 4. The polyurethane elastic yarn according to claim 1, wherein (b) is a polyoxyethylene alkyl ether. 5. The polyurethane elastic yarn according to claim 1 , further comprising a quaternary ammonium salt antibacterial agent. A method for producing an elastic polyurethane yarn, comprising: mixing a slightly water -soluble glass containing a Group 1B element and/or a Group 2B element into a spinning dope containing polyurethane, the starting materials of which are polymer diol and diisocyanate, in an amount of 0.5 to 5.0 mass % based on the total amount of the polyurethane and the slightly water-soluble glass ; mixing a nonionic surfactant in an amount of 0.01 to 20 mass parts based on 100 mass parts of the slightly water-soluble glass containing a Group 1B element and/or a Group 2B element; and dry-spinning the spinning dope. 7. The method for producing polyurethane elastic yarn according to claim 6 , wherein a slightly water-soluble glass containing a Group 1B element and/or a Group 2B element is mixed as a dispersion into a spinning dope containing polyurethane whose main starting materials are a polymer diol and a diisocyanate. The method for producing polyurethane elastic yarn according to claim 6 or 7 , wherein the Group 1B element and/or Group 2B element is silver and/or copper. The method for producing polyurethane elastic yarn according to any one of claims 6 to 8 , wherein (b) is polyoxyethylene alkyl ether.