Fiber treatment agent, coated fiber, shaped body, and method for manufacturing coated fiber and shaped body

Abstract

Provided are a fiber treatment agent, a coated fiber for which the fiber treatment agent is used and a method for manufacturing the same, and a shaped body including the coated fiber and a method for manufacturing the same, the fiber treatment agent containing: (A) a modified conjugated diene rubber; (B) an isocyanate compound that includes a ring structure and has, in each single molecule, two or more groups of one or more types selected from the group consisting of isocyanate groups and blocked isocyanate groups; and (C) an epoxy compound that has two or more epoxy groups in each single molecule.

Description

Fiber treatment agent, coated fiber, molded body, and method for producing coated fiber and molded body

[0001] The present invention relates to a fiber treatment agent, a coated fiber, a molded article, and a method for producing the coated fiber and the molded article.

[0002] Generally, industrial rubber products such as tires, conveyor belts, and hoses (e.g., automotive oil brake hoses) are reinforced with synthetic fibers such as vinylon and rayon, or natural fibers such as cotton. In these products, in order to fully utilize the excellent physical properties of rubber (e.g., high strength and high modulus of elasticity), it is necessary to firmly bond the fiber and rubber. A widely known method for achieving this is to use an adhesive called RFL, whose main components are resorcinol-formaldehyde resin and rubber latex (Patent Documents 1 and 2).

[0003] However, since formaldehyde is suspected of being carcinogenic and resorcinol is suspected of being an environmental hormone, there is a need to develop an alternative material to RFL.Patent Document 3 describes an aqueous adhesive for bonding fibers and elastomers, which is characterized by containing an oil-in-water emulsion (A) containing a liquid conjugated diene rubber and a surfactant, and an aqueous solution or dispersion (B) of a crosslinking agent, and a reinforcing fiber having the aqueous adhesive attached to the fiber.

[0004] Japanese Patent Application Laid-Open No. 54-4976 Japanese Patent Application Laid-Open No. 58-2370 International Publication No. 2023 / 085413

[0005] The reinforcing fiber described in Patent Document 3 has good adhesive strength to the rubber adherend (hereinafter also referred to as "adhered rubber"), but in order to further improve the durability of rubber products, further improvement in adhesive strength to the adhered rubber is required.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a fiber treatment agent that can produce coated fibers that have excellent adhesion to rubber coatings even without containing resorcinol and formaldehyde, a coated fiber using the fiber treatment agent and a method for producing the same, and a molded article that includes the coated fiber and a method for producing the same.

[0007] As a result of intensive research to solve the above-mentioned problems, the inventors have discovered that by using a fiber treatment agent having a specific composition, coated fibers having excellent adhesion to the rubber coating can be obtained even without containing resorcinol and formaldehyde, and have completed the present invention.

[0008] That is, the present invention relates to the following items [1] to

[14] . [1] A fiber treating agent comprising: (A) a modified conjugated diene rubber; (B) an isocyanate compound having a cyclic structure and having two or more groups per molecule, each of which is one or more groups selected from the group consisting of an isocyanate group and a blocked isocyanate group; and (C) an epoxy compound having two or more epoxy groups per molecule. [2] The fiber treating agent according to item [1] above, wherein the number average molecular weight (Mn) of the (A) modified conjugated diene rubber is 1,000 or more and 120,000 or less. [3] The fiber treating agent according to item [1] or [2] above, wherein the (A) modified conjugated diene rubber has monomer units derived from one or more selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, and farnesene. [4] The fiber treating agent according to any one of items [1] to [3] above, wherein the cyclic structure contained in component (B) is an aromatic ring. [5] A coated fiber comprising a fiber and a coating covering the surface of the fiber, wherein the coating comprises one or more selected from the group consisting of the fiber treatment agent described in any one of [1] to [4] above and a reaction product of the fiber treatment agent. [6] The coated fiber described in [5] above, wherein the reaction product of the fiber treatment agent is one or more selected from the group consisting of (A) modified conjugated diene rubbers bonded together via a crosslinking agent and (A) modified conjugated diene rubber and fiber bonded via a crosslinking agent. [7] The coated fiber described in [5] or [6] above, wherein the fiber is one or more selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers. [8] The coated fiber described in any one of [5] to [7] above, wherein the coating is applied in an amount of 5 to 15 parts by mass per 100 parts by mass of the fibers used as raw materials. [9] The coated fiber described in any one of [5] to [8] above, wherein the fiber is a spun yarn.

[10] A molded article comprising the coated fiber according to any one of [5] to [9] above.

[11] A method for producing the coated fiber according to any one of [5] to [9] above, comprising adhering the fiber treating agent to the fiber and then heating the fiber to form the coating.

[12] The method for producing a coated fiber according to

[11] above, wherein the fiber is one or more fibers selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers.

[13] The method for producing a coated fiber according to

[11] or

[12] above, wherein the amount of the coating applied is 5 to 15 parts by mass per 100 parts by mass of the fibers used as raw materials.

[14] The method for producing a coated fiber according to any of

[11] to

[13] above, wherein the fiber is a spun yarn.

[15] The method for producing a molded article using a coated fiber produced by the method for producing a coated fiber according to any of

[11] to

[14] above.

[0009] The present invention can provide a fiber treatment agent that can produce coated fibers that have excellent adhesion to rubber coatings even without containing resorcinol or formaldehyde, a coated fiber using the fiber treatment agent and a method for producing the same, and a molded article that includes the coated fiber and a method for producing the same.

[0010] [Fiber Treatment Agent] The fiber treatment agent of the present invention is a fiber treatment agent containing (A) a modified conjugated diene rubber, (B) an isocyanate compound having a cyclic structure and having two or more groups per molecule, each of which is one or more types of groups selected from the group consisting of an isocyanate group and a blocked isocyanate group (hereinafter also referred to as "(B) isocyanate compound"), and (C) an epoxy compound having two or more epoxy groups per molecule (hereinafter also referred to as "(C) epoxy compound").

[0011] The fiber treatment agent of the present invention is used to form a coating that coats the surface of a fiber, and coated fibers having a coating formed using the fiber treatment agent of the present invention exhibit excellent adhesion to the rubber substrate. The reason for this is presumed to be as follows: The (B) isocyanate compound and (C) epoxy compound contained in the fiber treatment agent of the present invention function as crosslinking agents for the (A) modified conjugated diene rubber. Therefore, in coated fibers formed using the fiber treatment agent of the present invention, the (A) modified conjugated diene rubbers and the (A) modified conjugated diene rubber and the fiber can be covalently bonded to each other via the crosslinking agent. As a result, even when the coated fiber of the present invention is vulcanized at high temperatures to adhere to the rubber substrate, the (A) modified conjugated diene rubber is less likely to be absorbed by the rubber substrate, and the coated fiber exhibits excellent adhesion to the rubber substrate. Furthermore, the (B) isocyanate compound contained in the fiber treatment agent of the present invention contains a cyclic structure, and the inclusion of this cyclic structure allows the fiber treatment agent of the present invention to exhibit superior adhesion to conventional fiber substrates. The reason for this is unclear, but it is speculated that one of the reasons is that the presence of the cyclic structure increases the rigidity of the molecule.

[0012] The fiber treating agent of the present invention is not particularly limited in form as long as it contains (A) a modified conjugated diene rubber, (B) an isocyanate compound, and (C) an epoxy compound, and may be in a state before being attached to a fiber or in a state after being attached to a fiber (i.e., in the form of a coating). From the viewpoint of handleability, the fiber treating agent of the present invention preferably contains a liquid medium such as a solvent or a dispersion medium, and each component is dissolved or dispersed in the liquid medium before being attached to a fiber. The liquid medium that can be contained in the fiber treating agent of the present invention is not particularly limited, but from the viewpoint of handleability, water is preferred. Hereinafter, each component contained in the fiber treating agent of the present invention will be described.

[0013] <(A) Modified Conjugated Diene Rubber> The (A) modified conjugated diene rubber is a rubber that contains at least a monomer unit derived from a conjugated diene (hereinafter also referred to as a "conjugated diene unit") in the molecule and has been modified to have a functional group other than a vinyl group contained in the conjugated diene unit. The (A) modified conjugated diene rubber preferably contains 50 mol % or more of the conjugated diene unit among all the monomer units in the (A) modified conjugated diene rubber. Examples of conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (hereinafter also referred to as "isoprene"), 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, chloroprene, farnesene, etc. These conjugated dienes may be used alone or in combination of two or more. From the viewpoint of reactivity during vulcanization, the (A) modified conjugated diene rubber preferably contains monomer units derived from one or more selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, and farnesene, and more preferably contains monomer units derived from one or more selected from the group consisting of 1,3-butadiene and isoprene.

[0014] The (A) modified conjugated diene rubber may contain other monomer units (hereinafter also referred to as "other monomer units") derived from monomers other than conjugated dienes, to the extent that the adhesion to the adherend rubber is not impaired. Examples of monomers other than conjugated dienes include copolymerizable ethylenically unsaturated monomers and aromatic vinyl compounds. Examples of ethylenically unsaturated monomers include olefins such as ethylene, 1-butene, and isobutylene, and acrylonitrile. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, divinylbenzene, etc. These monomers other than conjugated dienes may be used alone or in combination of two or more. When the (A) modified conjugated diene rubber contains the other monomer units, the content thereof is preferably 30 mol % or less, more preferably 10 mol % or less, and even more preferably 5 mol % or less, of the total monomer units in the (A) modified conjugated diene rubber.

[0015] The (A) modified conjugated diene rubber is not particularly limited as long as it has a functional group in part thereof, but one having a hydrogen-bonding functional group is preferred, and one containing a conjugated diene unit in at least a part of the polymer chain and having a hydrogen-bonding functional group in a side chain or terminal of the polymer chain is more preferred. The (A) modified conjugated diene rubber has a hydrogen-bonding functional group, which interacts with the rubber coating and the fiber, thereby more firmly adhering them together. Furthermore, when the (A) modified conjugated diene rubber and the rubber coating are vulcanized to form a covalent bond, a strong cohesive force is generated, further improving adhesion to the rubber coating. Furthermore, when hydrophilic fibers are used as the fibers, it is believed that the hydrogen-bonding functional group of the (A) modified conjugated diene rubber forms a hydrogen bond with the hydrophilic fiber, thereby improving adhesion.

[0016] In this specification, the term "hydrogen bond" refers to a bonding interaction formed between a hydrogen atom (donor) that is bonded to an atom with high electronegativity (such as O, N, or S) and is electrically positively polarized, and an electronegative atom (acceptor) that has a lone pair of electrons.

[0017] In the present invention, a "hydrogen-bonding functional group" refers to a functional group that can function as a donor or acceptor in a hydrogen bond. Specific examples include a hydroxy group, an ether group, a mercapto group, a carboxy group, a carbonyl group, an aldehyde group, an amino group, an imino group, an imidazole group, a urethane group, an amide group, a urea group, an isocyanate group, a nitrile group, a silanol group, and derivatives thereof. Examples of derivatives of aldehyde groups include acetalized derivatives thereof. Examples of derivatives of carboxy groups include salts thereof, esterified derivatives thereof, amidated derivatives thereof, and acid anhydrides thereof. Examples of derivatives of silanol groups include esterified derivatives thereof. Examples of carboxy groups include groups derived from monocarboxylic acids and groups derived from dicarboxylic acids. Among these, from the viewpoint of improving adhesion to the adherend rubber and from the viewpoint of ease of production of the (A) modified conjugated diene rubber, a hydroxy group, an aldehyde group, an acetalized product of an aldehyde group, a carbonyl group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a silanol group, an esterified product of a silanol group, an amino group, an imidazole group, and a mercapto group are preferred, a hydroxy group, a carboxy group, a carbonyl group, a salt of a carboxy group, an esterified product of a carboxy group, and an acid anhydride of a carboxy group are more preferred, a carboxy group, an esterified product of a carboxy group, and an acid anhydride of a carboxy group are even more preferred, and an esterified product of maleic anhydride and a functional group derived from maleic anhydride are even more preferred.

[0018] The hydrogen-bonding functional group possessed by the (A) modified conjugated diene rubber is preferably a functional group derived from one or more compounds selected from the group consisting of a radical-polymerizable compound having a hydrogen-bonding functional group and a silane compound having a hydrogen-bonding functional group, and more preferably a functional group derived from a radical-polymerizable compound having a hydrogen-bonding functional group.

[0019] The radical polymerizable compound having hydrogen-bonding functional group is not particularly limited, as long as it has both hydrogen-bonding functional group and reactive multiple bond in the molecule.Specifically, it can be mentioned aldehyde having reactive multiple bond, acetalized product of this aldehyde; monocarboxylic acid having reactive multiple bond, salt of this monocarboxylic acid, esterified product of this monocarboxylic acid, amide compound of this monocarboxylic acid, acid anhydride of this monocarboxylic acid; dicarboxylic acid having reactive multiple bond, salt of this dicarboxylic acid, esterified product of this dicarboxylic acid, amide compound of this dicarboxylic acid, imide compound derived from this dicarboxylic acid, acid anhydride of this dicarboxylic acid; amine compound having reactive multiple bond etc.These radical polymerizable compounds can be used alone or in combination of two or more.

[0020] Among aldehydes having a reactive multiple bond, examples of aldehydes having a reactive carbon-carbon double bond include acrolein, methacrolein, crotonaldehyde, 3-butenal, 2-methyl-2-butenal, 2-methyl-3-butenal, 2,2-dimethyl-3-butenal, 3-methyl-2-butenal, 3-methyl-3-butenal, 2-pentenal, 2-methyl-2-pentenal, 3-pentenal, 3- Methyl-4-pentenal, 4-pentenal, 4-methyl-4-pentenal, 2-hexenal, 3-hexenal, 4-hexenal, 5-hexenal, 7-octenal, 10-undecenal, 2-ethylcrotonaldehyde, 3-(dimethylamino)acrolein, myristoleinaldehyde, palmitoleinaldehyde, oleinaldehyde, elaidinaldehyde, vaccenaldehyde, gadoleinaldehyde Alkenals having 3 to 30 carbon atoms, preferably alkenals having 3 to 25 carbon atoms, such as erucaldehyde, nervonaldehyde, linolealdehyde, citronellal, cinnamaldehyde, and vanillin; alkadienals having 5 to 30 carbon atoms, preferably alkadienals having 5 to 25 carbon atoms, such as 2,4-pentadienal, 2,4-hexadienal, 2,6-nonadienal, and citral; linolenic aldehyde, eleostearic aldehyde, and the like. and unsaturated aldehydes such as alkatrienals having 7 to 30 carbon atoms, preferably alkatrienals having 7 to 25 carbon atoms, such as aldehyde; alkatetraenals having 9 to 30 carbon atoms, preferably alkatetraenals having 9 to 25 carbon atoms, such as stearidone aldehyde and arachidone aldehyde; and alkpentaenals having 11 to 30 carbon atoms, preferably alkpentaenals having 11 to 25 carbon atoms, such as eicosapentaene aldehyde. Note that, when the aldehydes have cis-trans isomers, both the cis and trans isomers are included.

[0021] Among acetalized products of aldehydes having a reactive multiple bond, examples of acetalized products of aldehydes having a reactive carbon-carbon double bond include acetalized products of the aldehydes, specifically, 3-(1,3-dioxalan-2-yl)-3-methyl-1-propene, which is an acetalized product of 2-methyl-3-butenal, and 3-(1,3-dioxalan-2-yl)-2-methyl-1-propene, which is an acetalized product of 3-methyl-3-butenal.

[0022] Among the aldehydes having a reactive multiple bond and acetalized products of the aldehydes, examples of the aldehydes having a reactive carbon-carbon triple bond and acetalized products thereof include aldehydes having a carbon-carbon triple bond such as propioaldehyde, 2-butyn-1-al, and 2-pentyn-1-al; and acetalized products of the aldehydes.

[0023] Among aldehydes having a reactive multiple bond and acetalized products of the aldehydes, aldehydes having a reactive carbon-carbon double bond are preferred, and examples thereof include acrolein, methacrolein, crotonaldehyde, 3-butenal, 2-methyl-2-butenal, 2-methyl-3-butenal, 2,2-dimethyl-3-butenal, 3-methyl-2-butenal, 3-methyl-3-butenal, 2-pentenal, 2-methyl-2-pentenal, 3-pentenal, 3-methyl-4-pentenal, 4-pentenal, 4-methyl-4-pentenal, 2-hexenal, 3-hexenal, 4-hexenal, 5-hexenal, 7-octenal, 2-ethylcrotonaldehyde, 3-(dimethylamino)acrolein, and 2,4-pentadienal. Among these, acrolein, methacrolein, crotonaldehyde and 3-butenal are more preferred because of their good reactivity during copolymerization.

[0024] Examples of the monocarboxylic acid having a reactive multiple bond, the salt of the monocarboxylic acid, the ester of the monocarboxylic acid, the amide compound of the monocarboxylic acid and the acid anhydride of the monocarboxylic acid include (meth)acrylic acid, the sodium salt of (meth)acrylic acid, the potassium salt of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate ... 2-Hydroxylbutyl acrylate, 3-hydroxylbutyl (meth)acrylate, 4-hydroxylbutyl (meth)acrylate, vinyl (meth)acrylate, 2-(trifluoromethyl)acrylic acid, methyl 2-trifluoromethylacrylate, ethyl 2-trifluoromethylacrylate, propyl 2-trifluoromethylacrylate, 2-butyl 2-trifluoromethylacrylate, 2-hydroxylethyl 2-trifluoromethylacrylate, vinyl 2-trifluoromethylacrylate, methyl cinnamate, vinyl cinnamate, methyl crotonate, crotonate vinyl phosphate, methyl 3-methyl-3-butenoate, vinyl 3-methyl-3-butenoate, methyl 4-pentenoate, vinyl 4-pentenoate, methyl 2-methyl-4-pentenoate, vinyl 2-methyl-4-pentenoate, methyl 5-hexenoate, vinyl 5-hexenoate, methyl 3,3-dimethyl-4-pentenoate, vinyl 3,3-dimethyl-4-pentenoate, methyl 7-octenoate, vinyl 7-octenoate, methyl trans-3-pentenoate, vinyl trans-3-pentenoate, methyl trans-4-decenoate, vinyl trans-4-decenoate, 3-methyl Ethyl 3-butenoate, ethyl 4-pentenoate, ethyl 2-methyl-4-pentenoate, ethyl 5-hexenoate, ethyl 3,3-dimethyl-4-pentenoate, ethyl 7-octenoate, ethyl trans-3-pentenoate, ethyl trans-4-decenoate, methyl 10-undecenoate, vinyl 10-undecenoate, (meth)acrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, cinnamic anhydride, crotonic anhydride, 3-methyl-3-butenoic anhydride, 4-pentenoic anhydride, 2-methyl-4-pentenoic anhydride, 5-hexenoic anhydride, 3,Examples of suitable carboxylic acids include carboxylic acids having a reactive carbon-carbon double bond, such as 3-dimethyl-4-pentenoic anhydride, 7-octenoic anhydride, trans-3-pentenoic anhydride, trans-4-decenoic anhydride, and 10-undecenoic anhydride, as well as salts of the carboxylic acids, esterified products of the carboxylic acids, and anhydrides of the carboxylic acids; and carboxylic acids having a reactive carbon-carbon triple bond, such as propiolic acid, methyl propiolate, ethyl propiolate, vinyl propiolate, tetrol acid, methyl tetrolate, ethyl tetrolate, and vinyl tetrolate, as well as esterified products of the carboxylic acids. In this specification, "(meth)acrylic acid" collectively refers to "acrylic acid" and "methacrylic acid."

[0025] Examples of dicarboxylic acids having a reactive multiple bond, salts of the dicarboxylic acid, esters of the dicarboxylic acid, amide compounds of the dicarboxylic acid, imide compounds derived from the dicarboxylic acid, and acid anhydrides of the dicarboxylic acid include dicarboxylic acids having a reactive multiple bond such as maleic acid, 2,3-dimethylmaleic acid, fumaric acid, citraconic acid, and itaconic acid; salts of dicarboxylic acids having a reactive multiple bond such as sodium maleate and potassium maleate; maleic acid esters (e.g., methyl maleate, dimethyl maleate), fumaric acid esters (e.g., methyl fumarate, dimethyl fumarate), citraconic acid esters (e.g., citric acid, esters of dicarboxylic acids having a reactive multiple bond, such as maleic acid amide, fumaric acid amide, citraconic acid amide, and itaconic acid amide; amide compounds of dicarboxylic acids having a reactive multiple bond, such as maleic acid imide, fumaric acid imide, citraconic acid imide, and itaconic acid imide; and anhydrides of dicarboxylic acids having a reactive multiple bond, such as maleic anhydride, 2,3-dimethylmaleic acid anhydride, citraconic acid anhydride, and itaconic acid anhydride.

[0026] As the monocarboxylic acid having a reactive multiple bond, the salt of the monocarboxylic acid, the ester of the monocarboxylic acid, the amide compound of the monocarboxylic acid, and the monocarboxylic acid anhydride, as well as the dicarboxylic acid having a reactive multiple bond, the salt of the dicarboxylic acid, the ester of the dicarboxylic acid, the amide compound of the dicarboxylic acid, the imide compound derived from the dicarboxylic acid, and the acid anhydride of the dicarboxylic acid, compounds having a reactive carbon-carbon double bond are preferred, and among them, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, vinyl (meth)acrylate, (meth)acrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, cinnamic anhydride, crotonic anhydride, methyl maleate, dimethyl maleate, maleic anhydride, methyl itaconate, dimethyl itaconate, and itaconic anhydride are more preferred because of their good reactivity during copolymerization.

[0027] Among the amine compounds having a reactive multiple bond, examples of amine compounds having a reactive carbon-carbon double bond include allylamine, 3-butenylamine, 4-pentenylamine, 5-hexenylamine, 6-heptenylamine, 7-octenylamine, oleylamine, 2-methylallylamine, 4-aminostyrene, 4-vinylbenzylamine, 2-allylglycine, S-allylcysteine, α-allylalanine, 2-allylaniline, geranylamine, vigabatrin, 4-vinylaniline, 4-vinyloxyaniline, etc. Among these, allylamine, 3-butenylamine, and 4-pentenylamine are preferred because of their good reactivity during copolymerization.

[0028] Examples of silane compounds having a hydrogen-bonding functional group include vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, mercaptomethylmethyldiethoxysilane, mercaptomethyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethylmethoxydimethylsilane, 2-mercaptoethylethoxydimethylsilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyldiethoxymethylsilane, 3-mercaptopropyldimethoxyethylsilane, 3-mercaptopropyldiethoxyethylsilane, 3-mercaptopropylmethoxydimethylsilane, and the like.

[0029] The number of hydrogen-bonding functional groups possessed by the (A) modified conjugated diene rubber is preferably 2 or more, and more preferably 3 or more, on average per molecule, from the viewpoint of improving adhesion to the adherend rubber. Furthermore, from the viewpoint of controlling the viscosity of the (A) modified conjugated diene rubber within an appropriate range and improving handleability, the number of hydrogen-bonding functional groups is preferably 80 or less, more preferably 40 or less, even more preferably 30 or less, even more preferably 20 or less, and even more preferably 10 or less, on average per molecule. From the same viewpoint, the number of hydrogen-bonding functional groups possessed by the (A) modified conjugated diene rubber is preferably 2 to 80, more preferably 3 to 40, even more preferably 3 to 30, and even more preferably 3 to 10, on average per molecule. The average number of hydrogen-bonding functional groups possessed by the (A) modified conjugated diene rubber can be calculated by the method described in the Examples.

[0030] Examples of methods for obtaining the (A) modified conjugated diene rubber include a method of adding a modifying compound to a polymer of a conjugated diene (hereinafter also referred to as "production method (1)"), a method of oxidizing a polymer of a conjugated diene (hereinafter also referred to as "production method (2)"), a method of copolymerizing a conjugated diene with a radically polymerizable compound having a hydrogen-bonding functional group (hereinafter also referred to as "production method (3)"), and a method of adding a modifying compound capable of reacting with an active polymerization terminal to a polymer of an unmodified conjugated diene having the active polymerization terminal before adding a polymerization terminator (hereinafter also referred to as "production method (4)").

[0031] (A) Manufacturing Method (1) of Modified Conjugated Diene Rubber Manufacturing method (1) is a method of adding a modifying compound to a polymer of conjugated diene, i.e., an unmodified conjugated diene rubber (hereinafter also referred to as "unmodified conjugated diene rubber"). The unmodified conjugated diene rubber can be obtained by polymerizing a conjugated diene and, if necessary, a monomer other than the conjugated diene, for example, by emulsion polymerization, solution polymerization, etc. Among the above methods, the solution polymerization method is preferred as the manufacturing method of the unmodified conjugated diene rubber.

[0032] As the solution polymerization method, known or equivalent methods can be applied. Specifically, for example, a method can be applied in which a predetermined amount of a monomer containing a conjugated diene is polymerized in a solvent using a Ziegler catalyst, a metallocene catalyst, an anionically polymerizable active metal, an anionically polymerizable active metal compound, or the like, optionally in the presence of a polar compound. Examples of solvents used in solution polymerization methods include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane, and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0033] Examples of the anionically polymerizable active metal include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among these, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred.

[0034] As the anionically polymerizable active metal compound, an organic alkali metal compound is preferred. Examples of the organic alkali metal compound include organic monolithium compounds such as methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; polyfunctional organic lithium compounds such as dilithiomethane, dilithionaphthalene, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; and sodium naphthalene and potassium naphthalene. Among these, organic lithium compounds are preferred, and organic monolithium compounds are more preferred. The amount of the organic alkali metal compound used can be appropriately determined depending on the melt viscosity, molecular weight, etc. of the desired unmodified conjugated diene rubber and (A) modified conjugated diene rubber, but is usually 0.01 to 3 parts by mass per 100 parts by mass of all monomers including conjugated dienes. The organic alkali metal compounds can also be reacted with secondary amines such as dibutylamine, dihexylamine, dibenzylamine, etc. to form organic alkali metal amides.

[0035] In anionic polymerization, polar compounds are usually used to adjust the microstructure of the conjugated diene moiety without deactivating the reaction. Examples of polar compounds include ether compounds such as dibutyl ether, tetrahydrofuran, ethylene glycol diethyl ether, and 2,2-di(2-tetrahydrofuryl)propane; tertiary amines such as tetramethylethylenediamine and trimethylamine; alkali metal alkoxides; and phosphine compounds. The polar compound is usually used in an amount of 0.01 to 1,000 moles per mole of the organic alkali metal compound.

[0036] The temperature for solution polymerization is usually −80 to +150° C., preferably 0 to 100° C., more preferably 10 to 90° C. The polymerization method may be either batchwise or continuous.

[0037] The polymerization reaction of solution polymerization can be terminated by adding a polymerization terminator. Examples of the polymerization terminator include alcohols such as methanol and isopropanol. The unmodified conjugated diene rubber can be isolated by pouring the resulting polymerization reaction solution into a poor solvent such as methanol to precipitate the polymer, or by washing the polymerization reaction solution with water, separating it, and then drying it.

[0038] As the emulsion polymerization method, known or similar methods can be used. Specifically, for example, a method can be used in which a predetermined amount of a monomer containing a conjugated diene is emulsified and dispersed in the presence of an emulsifier, followed by emulsion polymerization using a radical polymerization initiator. Examples of emulsifiers include long-chain fatty acid salts having 10 or more carbon atoms, rosin acid salts, etc. Examples of long-chain fatty acid salts having 10 or more carbon atoms include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid. Water is typically used as the dispersion solvent, and the dispersion may contain a water-soluble organic solvent such as methanol or ethanol, provided that stability during polymerization is not impaired. Examples of radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate; organic peroxides; and hydrogen peroxide. A chain transfer agent may be used to adjust the molecular weight of the resulting unmodified conjugated diene rubber. Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpenes, terpinolene, γ-terpinene, and α-methylstyrene dimer.

[0039] The temperature of the emulsion polymerization can be appropriately set depending on the type of radical polymerization initiator used, etc., but is usually 0 to 100° C., preferably 0 to 60° C. The polymerization method may be either batchwise or continuous.

[0040] The emulsion polymerization reaction can be terminated by adding a polymerization terminator, such as an amine compound such as isopropylhydroxylamine, diethylhydroxylamine, or hydroxylamine; a quinone compound such as hydroquinone or benzoquinone; or sodium nitrite.

[0041] After the polymerization reaction is terminated, an antioxidant may be added as needed. After the polymerization reaction is terminated, unreacted monomers are removed from the obtained latex as needed. Next, the polymer is coagulated using a salt such as sodium chloride, calcium chloride, or potassium chloride as a coagulant, and, as needed, an acid such as nitric acid or sulfuric acid is added to adjust the pH of the coagulation system to a predetermined value, and the dispersion solvent is separated to recover the polymer. Next, the polymer is washed with water, dehydrated, and then dried to obtain an unmodified conjugated diene rubber. Note that, during the coagulation, the latex and an extender oil previously prepared as an emulsified dispersion may be mixed as needed, and the oil-extended unmodified conjugated diene rubber may be recovered.

[0042] (Modified Compound Used in Production Method (1)) The modified compound used in Production Method (1) is not particularly limited, but from the viewpoint of improving adhesion to the adherend rubber, one having a hydrogen-bonding functional group is preferred. Examples of the hydrogen-bonding functional group include the same as those described above, and preferred embodiments are also similar. As the modified compound having a hydrogen-bonding functional group, the radical polymerizable compound having a hydrogen-bonding functional group and the silane compound having a hydrogen-bonding functional group, exemplified above, can be used. These modified compounds having a hydrogen-bonding functional group may be used alone or in combination of two or more.

[0043] The amount of the modifying compound used in the production method (1) is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 50 parts by mass, and even more preferably 1 to 30 parts by mass, per 100 parts by mass of the unmodified conjugated diene rubber.

[0044] The amount of the modifying compound added in the (A) modified conjugated diene rubber is preferably 0.5 to 40 parts by mass, more preferably 1 to 30 parts by mass, and even more preferably 1.5 to 20 parts by mass, per 100 parts by mass of the unmodified conjugated diene rubber. The amount of the modifying compound added in the (A) modified conjugated diene rubber can be calculated based on the acid value of the modifying compound, or can be determined using various analytical instruments such as infrared spectroscopy and nuclear magnetic resonance spectroscopy. Note that, since it is difficult to uniformly measure the amount of the modifying compound added using a specific measurement method, it is necessary to select an appropriate analytical method depending on the type of modifying compound used.

[0045] The method for adding the modifying compound to the unmodified conjugated diene rubber is not particularly limited, and examples thereof include a method in which a liquid unmodified conjugated diene rubber, one or more modifying compounds selected from the group consisting of unsaturated carboxylic acids, unsaturated carboxylic acid derivatives, and silane compounds, and an optional radical generator are heated in the presence or absence of an organic solvent. The radical generator used is not particularly limited, and commercially available organic peroxides, azo compounds, hydrogen peroxide, and the like can be used. The reaction temperature is typically preferably 0 to 200°C, more preferably 50 to 200°C. Examples of organic solvents include hydrocarbon solvents and halogenated hydrocarbon solvents. Among these, hydrocarbon solvents such as n-butane, n-hexane, n-heptane, cyclohexane, benzene, toluene, and xylene are preferred.

[0046] Alternatively, a modifying compound may be grafted onto an unmodified conjugated diene rubber to introduce a hydrogen-bonding functional group, and then a modifying compound capable of reacting with the functional group may be added to introduce another hydrogen-bonding functional group into the polymer. Specific examples of such methods include grafting maleic anhydride onto an unmodified conjugated diene rubber obtained by living anionic polymerization, followed by reaction with a compound having a hydroxyl group, such as 2-hydroxyethyl methacrylate or methanol, or a compound such as water.

[0047] Furthermore, when carrying out a reaction to add a modifying compound to an unmodified conjugated diene rubber, a modified conjugated diene rubber (a conjugated diene rubber having a hydrogen-bonding functional group introduced therein, obtained by the above-mentioned method), or the like, an antioxidant may be added from the viewpoint of suppressing side reactions. As the antioxidant, commercially available antioxidants can be used, and examples thereof include butylated hydroxytoluene (BHT) and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (for example, trade name "Nocrac 6C", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.). The amount of antioxidant added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the unmodified conjugated diene rubber. When the amount of antioxidant added is within the above range, side reactions can be suppressed, and the modified conjugated diene rubber (A) can be obtained in good yield.

[0048] (A) Manufacturing Method (2) of Modified Conjugated Diene Rubber Manufacturing method (2) is a method of oxidizing a conjugated diene polymer (unmodified conjugated diene rubber). Examples of manufacturing method (2) include a method of oxidizing a raw material unmodified conjugated diene rubber to obtain an oxidized conjugated diene rubber having an oxygen-containing functional group or bond generated in the molecule by an oxidation reaction. Examples of such oxygen-containing functional groups or bonds include a hydroxy group, an aldehyde group, a carbonyl group, a carboxy group, and an ether bond. The unmodified conjugated diene rubber can be obtained by a method similar to manufacturing method (1).

[0049] Examples of methods for oxidizing the unmodified conjugated diene rubber include a method of heat treating the unmodified conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (hereinafter also referred to as "production method (2-1)"), a method of irradiating the unmodified conjugated diene rubber with light having an absorption wavelength of the unmodified conjugated diene rubber to activate it and cause it to react with oxygen (hereinafter also referred to as "production method (2-2)"), etc. Among these, the method of heat treating the unmodified conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (production method (2-1)) is preferred.

[0050]

[0033] Production Method (2-1) of Oxidized Conjugated Diene Rubber

[0034] Production method (2-1) is a method of heat-treating an unmodified conjugated diene rubber at a temperature equal to or higher than its oxidation temperature. The heat treatment is carried out in an oxygen-containing atmosphere, preferably in an air atmosphere. The heat treatment temperature is not particularly limited as long as it is a temperature at which the unmodified conjugated diene rubber oxidizes; however, from the viewpoint of increasing the oxidation reaction rate and improving productivity, it is preferably 150°C or higher, more preferably 170°C or higher, and even more preferably 190°C or higher. When the oxidation of the unmodified conjugated diene rubber is carried out on the surface of hydrophilic fibers as described below, the heat treatment temperature is preferably 240°C or lower, more preferably 220°C or lower, from the viewpoint of preventing fiber degradation. The heat treatment time is not particularly limited as long as it is within a range in which the unmodified conjugated diene rubber does not deteriorate; however, it is preferably 30 minutes or lower, more preferably 20 minutes or lower. From the viewpoint of sufficiently oxidizing the unmodified conjugated diene rubber, the heat treatment time is preferably 1 second or longer, more preferably 10 seconds or longer, and even more preferably 30 seconds or longer.

[0051] Furthermore, the temperature required for the oxidation reaction can be lowered by adding a thermal radical generator to the unmodified conjugated diene rubber. Examples of thermal radical generators include peroxides, azo compounds, and redox initiators. Among these, peroxides are preferred from the viewpoint of bonding with the unmodified conjugated diene rubber and adding an oxygen-containing structure to the unmodified conjugated diene rubber. These thermal radical generators may be used alone or in combination of two or more.

[0052]

[0033] Production method (2-2) of oxidized conjugated diene rubber Production method (2-2) is a method in which unmodified conjugated diene rubber is activated by irradiating it with light of an absorption wavelength thereof, and reacting it with oxygen. Production method (2-2) is carried out in an oxygen-containing atmosphere, preferably in an air atmosphere. The wavelength of the light used is not particularly limited as long as it is a wavelength that is absorbed by the unmodified conjugated diene rubber and causes a radical reaction, but ultraviolet light, which is strongly absorbed by the unmodified conjugated diene rubber, is preferred.

[0053] Furthermore, by adding a photoradical generator to the unmodified conjugated diene rubber, it is possible to reduce the amount of light irradiation required for the oxidation reaction.

[0054] (A) Manufacturing Method (3) of Modified Conjugated Diene Rubber Manufacturing method (3) is a method of copolymerizing a conjugated diene and a radically polymerizable compound having a hydrogen-bonding functional group. Examples of manufacturing method (3) include random copolymerization, block copolymerization, or graft copolymerization of a conjugated diene and a radically polymerizable compound having a hydrogen-bonding functional group by a known method.

[0055] (Radical polymerizable compound having a hydrogen-bonding functional group used in production method (3)) The radical polymerizable compound having a hydrogen-bonding functional group used in production method (3) is not particularly limited as long as it is a compound having both a hydrogen-bonding functional group and a reactive multiple bond in the molecule, and specifically, the above-mentioned radical polymerizable compounds having a hydrogen-bonding functional group can be used.

[0056] (A) Manufacturing Method (4) of Modified Conjugated Diene Rubber Manufacturing method (4) is a method in which a modifying compound capable of reacting with an unmodified conjugated diene polymer having an active polymerization end (unmodified conjugated diene rubber) is added before adding a polymerization terminator. The unmodified conjugated diene rubber having an active polymerization end can be obtained by a method similar to that of manufacturing method (1). Examples of the modifying compound that can be used in production method (4) include modifying agents such as dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, 2,4-tolylenediisocyanate, carbon dioxide, ethylene oxide, succinic anhydride, 4,4′-bis(diethylamino)benzophenone, N-vinylpyrrolidone, N-methylpyrrolidone, 4-dimethylaminobenzylideneaniline, and dimethylimidazolidinone; and other modifying agents described in JP 2011-132298 A.

[0057] In the production method (4), for example, when an organic alkali metal compound is used for polymerization, the amount of the modifying compound used is preferably 0.01 to 100 molar equivalents relative to the organic alkali metal compound. The reaction temperature is usually −80 to +150° C., preferably 0 to 100° C., and more preferably 10 to 90° C. Alternatively, the modifying compound may be added before the addition of the polymerization terminator to introduce a hydrogen-bonding functional group into the unmodified conjugated diene rubber, and then a modifying compound capable of reacting with the hydrogen-bonding functional group may be added to introduce another hydrogen-bonding functional group into the polymer.

[0058] There are no particular limitations on the method for producing the modified conjugated diene rubber (A). However, from the viewpoint of productivity, it is preferable to produce it by the production method (1), (2) or (3), more preferably by the production method (1) or (3), and even more preferably by the production method (1).

[0059] (Physical Properties of (A) Modified Conjugated Diene Rubber) The weight average molecular weight (Mw) of the (A) modified conjugated diene rubber is not particularly limited, but from the viewpoint of improving adhesion to the adherend rubber, it is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, even more preferably 4,000 or more, even more preferably 5,000 or more, and may be 7,000 or more, and from the viewpoint of handleability, it is preferably 120,000 or less, more preferably 50,000 or less, even more preferably 26,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 12,000 or less, and even more preferably 10,000 or less. The fiber treatment agent of the present invention may contain two or more different types of (A) modified conjugated diene rubber. Here, "the type of modified conjugated diene rubber (A) is different" means that at least one of various physical properties and characteristics such as the type of monomer unit contained, the type of functional group, the number of functional groups, the weight average molecular weight, and the number average molecular weight is different.

[0060] The number average molecular weight (Mn) of the (A) modified conjugated diene rubber is not particularly limited, but from the viewpoint of improving adhesion to the adherend rubber, it is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 2,500 or more, even more preferably 3,000 or more, and even more preferably 3,500 or more, and from the viewpoint of handleability, it is preferably 120,000 or less, more preferably 50,000 or less, even more preferably 20,000 or less, even more preferably 18,000 or less, and even more preferably 15,000 or less. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the (A) modified conjugated diene rubber are polystyrene-equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC) measurement, and specifically can be determined by the method described in the examples. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the (A) modified conjugated diene rubber can be adjusted to desired values ​​by adjusting the type and amount of the solvent in the production method.

[0061] The molecular weight distribution (Mw / Mn) of the (A) modified conjugated diene rubber is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, even more preferably 1.0 to 2.0, even more preferably 1.0 to 1.5, and even more preferably 1.0 to 1.3. When the molecular weight distribution (Mw / Mn) is within the above range, the viscosity of the (A) modified conjugated diene rubber varies little, making it easy to handle. The molecular weight distribution (Mw / Mn) means the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in terms of polystyrene, as determined by GPC measurement.

[0062] From the viewpoint of adhesiveness to fibers, the (A) modified conjugated diene rubber is preferably liquid. In this specification, "liquid" means that the (A) modified conjugated diene rubber has a melt viscosity of 4,000 Pa·s or less at 38°C. From the viewpoint of improving adhesiveness to fibers, the melt viscosity of the (A) modified conjugated diene rubber at 38°C is preferably 0.1 Pa·s or more, more preferably 0.5 Pa·s or more, and even more preferably 1.0 Pa·s or more, and from the viewpoint of handleability, it is preferably 2,000 Pa·s or less, more preferably 1,500 Pa·s or less, and even more preferably 1,000 Pa·s or less. When the melt viscosity is within the above range, handleability can be improved while improving adhesiveness to fibers. The melt viscosity of the (A) modified conjugated diene rubber means the viscosity measured at 38°C using a Brookfield viscometer (B-type viscometer), and specifically can be determined by the method described in the examples.

[0063] The glass transition temperature (Tg) of the (A) modified conjugated diene rubber may vary depending on the vinyl content of the conjugated diene units, the type of conjugated diene, the content of monomer units derived from monomers other than the conjugated diene, etc., but is preferably -100 to +10°C, more preferably -100 to 0°C, and even more preferably -100 to -5°C. When the glass transition temperature (Tg) is within the above range, an increase in viscosity can be suppressed, making handling easier. The glass transition temperature (Tg) of the (A) modified conjugated diene rubber can be determined by the method described in the examples.

[0064] The vinyl content of the (A) modified conjugated diene rubber is preferably 80 mol% or less, more preferably 50 mol% or less, and even more preferably 30 mol% or less. When the vinyl content is within the above range, adhesion to the adherend rubber is improved. In this specification, "vinyl content" means the total mol% of conjugated diene units bonded via 1,2-bonds or 3,4-bonds (conjugated diene units bonded via bonds other than 1,4-bonds) out of a total of 100 mol% of conjugated diene units contained in the (A) modified conjugated diene rubber. The vinyl content is １Using H-NMR, it can be calculated from the ratio of the integral values ​​of the signal derived from the conjugated diene units bonded via 1,2- or 3,4-bonds to the signal derived from the conjugated diene units bonded via 1,4-bonds.

[0065] (Content of (A) Modified Conjugated Diene Rubber) From the viewpoint of improving adhesion to the adherend rubber, the content of the (A) modified conjugated diene rubber in the fiber treatment agent of the present invention is preferably 20 mass % or more, more preferably 30 mass % or more, and even more preferably 40 mass % or more, of the total amount of all components excluding the liquid medium in the fiber treatment agent, and is preferably 90 mass % or less, more preferably 85 mass % or less, and even more preferably 80 mass % or less.

[0066] The content of the modified conjugated diene rubber (A) in the fiber treating agent of the present invention before application to fibers is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 4% by mass or more, and is preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less. When the content of the modified conjugated diene rubber (A) is within the above range, excellent adhesion to the adherend rubber can be obtained, while preventing the viscosity of the fiber treating agent before application to fibers from becoming extremely high.

[0067] <(B) Isocyanate Compound Having a Cyclic Structure and Having Two or More Groups Selected from the Group Consisting of Isocyanate Groups and Blocked Isocyanate Groups Per Molecule> The (B) isocyanate compound is not particularly limited as long as it is an isocyanate compound having two or more groups selected from the group consisting of isocyanate groups and blocked isocyanate groups per molecule. In the present invention, the blocked isocyanate group that component (B) may have is a group formed by adding a blocking agent to an isocyanate group. From the viewpoint of improving adhesion to the adherend rubber, the number of groups selected from the group consisting of isocyanate groups and blocked isocyanate groups per molecule of the (B) isocyanate compound is two or more, and preferably five or less, more preferably four or less, and even more preferably three or less.

[0068] From the viewpoint of storage stability of the fiber treatment agent, the isocyanate compound (B) is preferably a blocked isocyanate compound having a blocked isocyanate group. Examples of blocking agents that form blocked isocyanate groups include lactam compounds such as γ-butyrolactam, ε-caprolactam, γ-valerolactam, and propiolactam; oxime compounds such as methyl ethyl ketone oxime, methyl isoamyl ketone oxime, methyl isobutyl ketone oxime, formamide oxime, acetamide oxime, acetoxime, diacetyl monooxime, benzophenone oxime, and cyclohexanone oxime; monocyclic phenol compounds such as phenol, cresol, catechol, and nitrophenol; polycyclic phenol compounds such as 1-naphthol; alcohol compounds such as methyl alcohol, ethyl alcohol, isopropyl alcohol, tert-butyl alcohol, trimethylolpropane, and 2-ethylhexyl alcohol; ether compounds such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether; and active methylene compounds such as malonic acid alkyl esters, malonic acid dialkyl esters, acetoacetic acid alkyl esters, and acetylacetone. These blocking agents may be used alone or in combination of two or more. From the viewpoint of the storage stability of the fiber treatment agent, the blocked isocyanate compound is preferably a compound having only a blocked isocyanate group, out of an isocyanate group and a blocked isocyanate group.

[0069] The (B) isocyanate compound contained in the fiber treatment agent of the present invention contains a cyclic structure in its molecule. The (B) isocyanate compound is preferably represented by the following general formula (1): X-R-X (1) (wherein X represents one or more groups selected from the group consisting of an isocyanate group and a blocked isocyanate group, and R represents a divalent group containing one or more cyclic structures.) Examples of the cyclic structure include an aromatic ring, a heterocyclic ring, and an aliphatic ring. Among these, the (B) isocyanate compound preferably contains an aromatic ring as its cyclic structure. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and an anthracene ring. Among these, a benzene ring is preferred. From the viewpoint of improving adhesion to the adherend rubber, the number of cyclic structures contained in one molecule of the (B) isocyanate compound is one or more, and preferably four or less, more preferably three or less, and even more preferably two or less.

[0070] Examples of the isocyanate compound (B) having an aliphatic ring include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and adducts of blocking agents with these isocyanate compounds having an aliphatic ring. Examples of the isocyanate compound (B) having an aromatic ring include tolylene diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 2,5-tolylene diisocyanate; xylylene diisocyanates such as o-xylylene diisocyanate, m-xylylene diisocyanate, and p-xylylene diisocyanate; isocyanate compounds having one aromatic ring such as 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate; and blocking agent adducts of these isocyanate compounds having aromatic rings. Among these, isocyanate compounds having one or two aromatic rings and their blocking agent adducts are preferred from the viewpoint of improving adhesion to the adherend rubber. As the isocyanate compound having one aromatic ring and its blocking agent adduct, tolylene diisocyanate and a blocking agent adduct of tolylene diisocyanate are preferred. As the isocyanate compound having two aromatic rings and its blocking agent adduct, 4,4'-diphenylmethane diisocyanate and a blocking agent adduct of 4,4'-diphenylmethane diisocyanate are preferred.

[0071] From the viewpoint of improving adhesion to the adherend rubber, the content of the (B) isocyanate compound in the fiber treating agent of the present invention is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, per 100 parts by mass of the (A) modified conjugated diene rubber. From the same viewpoint, the content of the (B) isocyanate compound in the fiber treating agent of the present invention is preferably 10 to 70 parts by mass, more preferably 15 to 60 parts by mass, and even more preferably 20 to 50 parts by mass, per 100 parts by mass of the (A) modified conjugated diene rubber.

[0072] <(C) Epoxy Compound Having Two or More Epoxy Groups per Molecule> The (C) epoxy compound contained in the fiber treatment agent of the present invention is not particularly limited as long as it is an epoxy compound having two or more epoxy groups per molecule. From the viewpoint of improving adhesion to the adherend rubber, the number of epoxy groups per molecule of the (C) epoxy compound is two or more, preferably three or more, more preferably four or more, and is preferably eight or less, more preferably seven or less, and even more preferably six or less. From the same viewpoint, the number of epoxy groups per molecule of the (C) epoxy compound is preferably two to eight, more preferably three to seven, and even more preferably four to six.

[0073] As the epoxy compound (C), either an aliphatic epoxy compound or an aromatic epoxy compound can be used, but from the viewpoint of improving adhesion to the adherend rubber, an aliphatic epoxy compound is preferred. Examples of the aliphatic epoxy compound include bifunctional aliphatic epoxy compounds and trifunctional or higher aliphatic epoxy compounds. Examples of the bifunctional aliphatic epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and polypropylene glycol diglycidyl ether. Examples of trifunctional or higher aliphatic epoxy compounds include sorbitol polyglycidyl ethers such as sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, sorbitol pentaglycidyl ether, and sorbitol hexaglycidyl ether; glycerol polyglycidyl ethers such as glycerol triglycidyl ether; trimethylolpropane polyglycidyl ether such as trimethylolpropane triglycidyl ether; and polyglycerol polyglycidyl ethers such as diglycerol tetraglycidyl ether and diglycerol triglycidyl ether. These (C) epoxy compounds may be used alone or in combination of two or more. Among these, from the viewpoint of improving adhesion to the rubber coating, sorbitol polyglycidyl ether is preferred, and sorbitol tetraglycidyl ether is more preferred.

[0074] From the viewpoint of improving adhesion to the adherend rubber, the content of the epoxy compound (C) in the fiber treatment agent of the present invention is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, and is preferably 55 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of the modified conjugated diene rubber (A). From the same viewpoint, the content of the epoxy compound (C) in the fiber treatment agent of the present invention is preferably 5 to 55 parts by mass, more preferably 10 to 45 parts by mass, and even more preferably 15 to 35 parts by mass, per 100 parts by mass of the modified conjugated diene rubber (A).

[0075] <(D) Surfactant> The fiber treating agent of the present invention preferably further contains (D) a surfactant. By containing (D) a surfactant in the fiber treating agent of the present invention, the long-term storage stability of the fiber treating agent can be improved in a state of emulsion in which oil droplets containing the (A) modified conjugated diene rubber are dispersed in water, and the fiber treating agent can be adhered to fibers more uniformly and efficiently.

[0076] Examples of the surfactant (D) include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are preferred from the viewpoint of compatibility between the fiber treatment agent and the rubber coating. These surfactants (D) may be used alone or in combination of two or more.

[0077] Examples of nonionic surfactants include polyoxyalkylene-type nonionic surfactants such as higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts, styrenated phenol alkylene oxide adducts, fatty acid alkylene oxide adducts, polyhydric alcohol aliphatic ester alkylene oxide adducts, higher alkylamine alkylene oxide adducts, and fatty acid amide alkylene oxide adducts; and polyhydric alcohol-type nonionic surfactants such as alkylglycoxides and sucrose fatty acid esters. Commercially available nonionic surfactants include, for example, "Adeka Tol UA-90N," "Adeka Tol TN-100," "Adeka Tol PC-6," "Adeka Tol PC-8," "Adeka Tol PC-10," and "Adeka Tol SO-80," manufactured by ADEKA Corporation.

[0078] Examples of cationic surfactants include alkylammonium acetate salts, alkyldimethylbenzylammonium salts, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkylpyridinium salts, oxyalkylene alkylamines, and polyoxyalkylene alkylamines.

[0079] Examples of anionic surfactants include carboxylates such as fatty acid soaps; sulfate salts such as higher alcohol sulfate salts, higher alkyl polyalkylene glycol ether sulfate salts, sulfate salts of styrenated phenol alkylene oxide adducts, sulfate salts of alkylphenol alkylene oxide adducts, sulfated oils, sulfated fatty acid esters, sulfated fatty acids, and sulfated olefins; sulfonates such as alkylbenzenesulfonates, alkylnaphthalenesulfonates, naphthalenesulfonates, and formalin condensate salts of naphthalenesulfonic acid, α-olefinsulfonates, paraffin sulfonates, and sulfosuccinic acid diester salts; and higher alcohol phosphate salts. Furthermore, a nonionic surfactant and an anionic surfactant may be combined as necessary.

[0080] Examples of zwitterionic surfactants include alkylcarboxybetaines.

[0081] The HLB (Hydrophilic-Lipophilic Balance) value of the nonionic surfactant is preferably 6 to 17. When the HLB value is within this range, the compatibility with (A) the modified conjugated diene rubber is good, and a coated fiber having better adhesion to the rubber substrate can be obtained. From the viewpoint of storage stability in water, the lower limit of the HLB value is more preferably 8 or more, and even more preferably 10 or more. From the viewpoint of compatibility with the fiber treatment agent and adhesion to the rubber substrate, the upper limit of the HLB value is more preferably 16 or less, and even more preferably 14 or less. The HLB value is an index showing the balance of hydrophilicity and lipophilicity, and is expressed as a value from 0 to 20. For example, it can be calculated by the following formula (I) based on the Griffin method: HLB value = 20 × sum of formula weights of hydrophilic moieties / molecular weight (I) The nonionic surfactant is identified by detecting and measuring the molecular weight and constitutional units using mass spectrometry, １ H and １３The structure can be detected and measured using C-NMR, and the structure can be identified based on this, so the HLB value can be calculated using formula (I) based on the identified information. Methods for separating nonionic surfactants from fiber treatment agents include, for example, fractionation and isolation by reverse phase liquid chromatography.

[0082] From the viewpoint of improving emulsion stability, the content of the surfactant (D) in the fiber treating agent of the present invention is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the modified conjugated diene rubber (A). From the same viewpoint, the content of the surfactant (D) in the fiber treating agent of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the modified conjugated diene rubber (A).

[0083] <(E) Oil having a vapor pressure of 10 Pa or less at 20°C> The fiber treatment agent of the present invention may further contain (E) oil having a vapor pressure of 10 Pa or less at 20°C (hereinafter also referred to as "(E) oil").

[0084] The (E) oil is not particularly limited as long as it is compatible with the (A) modified conjugated diene rubber, and examples thereof include natural oils, synthetic oils, etc. Examples of natural oils include mineral oils, vegetable oils, etc. Examples of mineral oils include paraffinic mineral oils, aromatic mineral oils, and naphthenic mineral oils obtained by conventional refining methods such as solvent refining and hydrogenation refining; waxes (gas-to-liquid waxes) produced by the Fischer-Tropsch process; and mineral oils produced by isomerizing wax. Examples of commercially available paraffinic mineral oils include the "Diana Process Oil" series manufactured by Idemitsu Kosan Co., Ltd. and the "Super Oil" series manufactured by JX Nippon Oil & Energy Corporation. Examples of vegetable oils include linseed oil, camellia oil, macadamia nut oil, corn oil, mink oil, olive oil, avocado oil, camellia oil, castor oil, safflower oil, jojoba oil, sunflower oil, almond oil, rapeseed oil, sesame oil, soybean oil, peanut oil, cottonseed oil, coconut oil, palm kernel oil, and rice bran oil.

[0085] Examples of synthetic oils include hydrocarbon synthetic oils, ester synthetic oils, and ether synthetic oils. Examples of hydrocarbon synthetic oils include α-olefin oligomers such as polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, and ethylene-propylene copolymer, or hydrogenated products thereof; alkylbenzenes, and alkylnaphthalenes. Examples of ester synthetic oils include triglycerin fatty acid esters, diglycerin fatty acid esters, monoglycerin fatty acid esters, monoalcohol fatty acid esters, and polyhydric alcohol fatty acid esters. Examples of ether synthetic oils include polyoxyalkylene glycols and polyphenyl ethers. Examples of commercially available synthetic oils include the "Linearene" series manufactured by Idemitsu Kosan Co., Ltd., and "FGC32," "FGC46," and "FGC68" manufactured by ANDEROL.

[0086] When the fiber treatment agent contains (E) oil, the content thereof is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 50 parts by mass or less, per 100 parts by mass of the (A) modified conjugated diene rubber. From the same viewpoint, when the fiber treatment agent contains (E) oil, the content thereof is preferably more than 0 parts by mass and 300 parts by mass or less, more preferably more than 0 parts by mass and 200 parts by mass or less, even more preferably more than 0 parts by mass and 100 parts by mass or less, and even more preferably more than 0 parts by mass and 50 parts by mass or less, per 100 parts by mass of the (A) modified conjugated diene rubber. In addition, the fiber treatment agent does not have to contain (E) oil.

[0087] <Other Components> The fiber treating agent of the present invention may contain other components in addition to the above-mentioned components, as long as the adhesiveness to the adherend rubber is not impaired. Examples of the other components include a polymer other than the (A) modified conjugated diene rubber (e.g., an unmodified conjugated diene rubber), an acid, an alkali, an inorganic salt, an organic salt, an antioxidant, a curing agent, a polymerization initiator, a dispersant, a pigment, a dye, an adhesion aid, a plasticizer, and carbon black. When the fiber treating agent contains the other components, the content thereof is preferably 10,000 parts by mass or less, more preferably 1,000 parts by mass or less, even more preferably 100 parts by mass or less, still more preferably 50 parts by mass or less, still more preferably 25 parts by mass or less, and still more preferably 10 parts by mass or less, per 100 parts by mass of the (A) modified conjugated diene rubber.

[0088] In the present invention, a coated fiber having excellent adhesion to the rubber coating can be obtained even without containing formaldehyde, formaldehyde-based resins, resorcinol, or the like, which are harmful to the human body. Examples of formaldehyde-based resins include resorcinol / formaldehyde resins, phenol / formaldehyde resins, melamine / formaldehyde resins, and derivatives thereof. When the fiber treatment agent of the present invention contains one or more resins selected from the group consisting of formaldehyde and formaldehyde-based resins, the content thereof is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the (A) modified conjugated diene rubber. It is particularly preferable that the fiber treatment agent be substantially free of formaldehyde. The formaldehyde content can be measured by extracting the coating from the coated fiber with a solvent such as toluene and then using HPLC or the like. When the fiber treatment agent of the present invention contains resorcinol, the content thereof is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, relative to 100 parts by mass of the (A) modified conjugated diene rubber, and it is particularly preferable that the fiber treatment agent is substantially free of resorcinol.

[0089] As described above, before the fiber treating agent of the present invention is applied to fibers, each component is preferably dissolved or dispersed in a liquid medium, and more preferably dissolved or dispersed in water. From the viewpoints of adhesiveness and ease of handling, the total amount of components other than the liquid medium of the fiber treating agent of the present invention before application to fibers is preferably 2 to 25% by mass, more preferably 5 to 20% by mass, and even more preferably 10 to 16% by mass. When the total amount of components other than the liquid medium is within the above range, the fiber treating agent can be efficiently applied to fibers, and the fiber treating agent is less likely to adhere to production equipment, thereby suppressing contamination of the production equipment.

[0090] <Method for producing fiber treating agent> The method for producing the fiber treating agent of the present invention is not particularly limited, and the agent can be produced by mixing the respective components. Specifically, for example, the agent can be produced by mixing (A) modified conjugated diene rubber, (B) isocyanate compound, (C) epoxy compound, liquid medium, and other components contained as necessary by a known method.

[0091] When the fiber treatment agent of the present invention is made into an emulsion, the emulsion can be prepared by any method, including mechanical or chemical methods. Mechanical methods include, for example, methods using a homogenizer, homomixer, disperser mixer, colloid mill, pipeline mixer, high-pressure homogenizer, ultrasonic emulsifier, etc., and these methods can be used alone or in combination. Chemical methods include, for example, inversion emulsification, D-phase emulsification, HLB temperature emulsification, gel emulsification, and liquid crystal emulsification. Among these, inversion emulsification is preferred from the viewpoint of easily obtaining an emulsion with a fine particle size. Furthermore, in order to obtain an emulsion with a fine particle size, it may be preferable to carry out the process while heating to an appropriate temperature (e.g., 30 to 80°C) in order to reduce the viscosity of the (A) modified conjugated diene rubber.

[0092] In the present invention, for the purpose of improving the stability of the emulsion, an alkaline substance such as sodium hydroxide, potassium hydroxide, or amines may be added as needed to adjust the pH before use. When an alkaline substance is added, the amount of the alkaline substance added per 100 parts by mass of the (A) modified conjugated diene rubber in the emulsion is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 1 part by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of improving the stability of the emulsion. From the same viewpoint, when an alkaline substance is added, the amount of the alkaline substance added per 100 parts by mass of the (A) modified conjugated diene rubber in the emulsion is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass.

[0093] When producing the fiber treatment agent of the present invention, the order of mixing the various components is not particularly limited, but it is preferable to mix an emulsion in which oil droplets containing (A) a modified conjugated diene rubber are dispersed in water, an isocyanate compound (B), and an epoxy compound (C), and when the fiber treatment agent of the present invention contains (E) oil, it is more preferable to mix an emulsion in which oil droplets containing (A) a modified conjugated diene rubber and (E) oil are dispersed in water, an isocyanate compound (B), and an epoxy compound (C). The (B) isocyanate compound and the (C) epoxy compound may be mixed with other components in a state where they are dissolved or dispersed in a liquid medium.

[0094] [Coated fiber and manufacturing method thereof] The coated fiber of the present invention comprises a fiber and a coating that coats the surface of the fiber, wherein the coating comprises one or more selected from the group consisting of the fiber treatment agent of the present invention and a reaction product of the fiber treatment agent. Note that the "coated fiber" in the present invention is a fiber in which at least a portion of the surface is coated with the coating, and may be in a form in which the coating exists on at least a portion of the surface of the fiber as, for example, a film, layer, or the like.

[0095] <Fiber> The fiber contained in the covered fiber of the present invention is not particularly limited, and examples thereof include synthetic fibers, natural fibers, and regenerated fibers.

[0096] Examples of synthetic fibers include polyamide fibers, polyvinyl alcohol fibers, polyester fibers, regenerated cellulose fibers, polyacrylamide fibers, polyolefin fibers, wholly aromatic polyester fibers, etc. Among these, one or more fibers selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers are preferred, and one or more fibers selected from the group consisting of polyvinyl alcohol fibers and polyester fibers are more preferred.

[0097] Examples of natural fibers include natural cellulose fibers such as wood pulp such as kraft pulp and non-wood pulp such as cotton pulp and straw pulp. Examples of regenerated fibers include regenerated cellulose fibers such as rayon, lyocell, cupra, and polynosic. These fibers may be used alone or in combination of two or more.

[0098] The fibers used in the coated fibers of the present invention may be short fibers or long fibers. Furthermore, the fibers used in the coated fibers of the present invention may be in the form of monofilaments, multifilaments, or spun yarns. Among these, spun yarns are preferred from the viewpoints of processability and adhesion to the rubber coating. When spun yarns are used, some of the fibers constituting the spun yarn deviate from the main axis of the yarn and are exposed on the fiber surface, thereby achieving higher adhesive strength. The fineness of the spun yarn is not particularly limited, but is preferably 3 to 100 count, more preferably 4 to 90 count, and even more preferably 5 to 70 count, in terms of cotton count. In the case of monofilaments, the single yarn fineness is preferably 30 to 20,000 dtex, more preferably 100 to 10,000 dtex, and even more preferably 300 to 5,000 dtex. In the case of multifilaments, the single yarn fineness is preferably 0.1 to 30.0 dtex, more preferably 0.5 to 15.0 dtex, and even more preferably 1.0 to 10.0 dtex, and the total fineness is preferably 50 to 10,000 dtex, more preferably 100 to 6,000 dtex, and even more preferably 250 to 4,500 dtex. These fibers may be in the form of nonwoven fabric, woven fabric, knitted fabric, felt, sponge, etc. In the present invention, one type of fiber may be used alone, or two or more types may be used in combination.

[0099] In the coated fiber of the present invention, the amount of the coating attached is preferably 5 to 15 parts by mass, more preferably 6 to 12 parts by mass, and even more preferably 7 to 10 parts by mass, per 100 parts by mass of the fiber used as the raw material, from the viewpoint of improving adhesion to the coated rubber.

[0100] In the coated fiber of the present invention, the total content of the fiber and one or more selected from the group consisting of fiber treatment agents and reaction products of the fiber treatment agents is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, from the viewpoints of improving adhesion to the adhered rubber and reinforcing strength.

[0101] The coated fiber of the present invention can be used in any shape, but is preferably used in the form of a fiber cord, woven fabric, knitted fabric, etc., which at least partially comprises the coated fiber, and more preferably used as a woven fabric or knitted fabric which at least partially comprises the coated fiber. For example, as described below, it can be used as a woven fabric to be adhered to a rubber component. It can also be used as a coated fiber to be embedded in resin, cement, etc. One example of using the coated fiber of the present invention in the form of a woven fabric is tire bead tape. Bead tape is wrapped around multiple bead wires embedded in the bead portion of a tire to prevent the bead wires from becoming distorted during vulcanization and to improve adhesion to the carcass. The coated fiber of the present invention has high adhesion to the rubber coating, making it suitable for bead tape, which requires durability.

[0102] According to the present invention, a coated fiber having excellent rubber adhesion can be obtained. Specifically, the rubber adhesion can be 45.0 N / 25.4 mm or more, 50.0 N / 25.4 mm or more, 55.0 N / 25.4 mm or more, 60.0 N / 25.4 mm or more, and even 63.0 N / 25.4 mm or more. The rubber adhesion of the coated fiber can be measured by the method described in the examples.

[0103] <Method for Producing Coated Fibers> While there are no particular limitations on the method for producing the coated fibers of the present invention, a method in which the fiber treating agent of the present invention is applied to a fiber and then heated to form a coating is preferred. This method is preferable because the fiber treating agent applied to the fiber reacts upon heating, resulting in a coating containing the fiber treating agent reaction product covering the fiber. The fiber treating agent reaction product is preferably one or more selected from the group consisting of (A) modified conjugated diene rubbers bonded together via a crosslinking agent and (A) modified conjugated diene rubber and fiber bonded together via a crosslinking agent. When the fiber treating agent reaction product contains (A) modified conjugated diene rubbers bonded together via a crosslinking agent, the reaction product contains a crosslinked product of appropriate molecular weight, improving process contamination while maintaining adhesion to the adhered rubber. Furthermore, when the fiber treating agent reaction product contains (A) modified conjugated diene rubber and fiber bonded together via a crosslinking agent, adhesion to the adhered rubber is particularly improved. More specifically, the method for producing the coated fiber of the present invention preferably comprises the following steps I-1 and I-2 in this order: Step I-1: A step of attaching a fiber treatment agent to the surface of the fiber; Step I-2: A step of heat-treating the fiber obtained in Step I-1 and having the fiber treatment agent attached to its surface.

[0104] <Step I-1: Step of Adhering a Fiber Treatment Agent to the Surface of a Fiber> In step I-1, the method of adhering the fiber treatment agent to the surface of a fiber is not particularly limited, and examples include a method of adhering the fiber treatment agent directly to the surface of a fiber, a method of adding a solvent to the fiber treatment agent and then adhering it to the surface of a fiber, etc. The step of adhering the fiber treatment agent to the surface of a fiber is preferably carried out by, for example, one or more methods selected from the group consisting of immersion, roll coater, oiling roller, oiling guide, nozzle (spray) application, and brush application.

[0105] <Step I-2: Heat-treating the fiber obtained in Step I-1 and having a fiber treatment agent adhered to its surface> The heat treatment in Step I-2 is preferably carried out at a treatment temperature of 100 to 250°C for a treatment time of 0.1 seconds to 2 minutes. Because the (A) modified conjugated diene rubber contained in the fiber treatment agent has reactive multiple bonds, the heat treatment temperature in the presence of oxygen is preferably 240°C or lower, more preferably 220°C or lower. When the heat treatment temperature is within the above range, a coated fiber having excellent adhesion to the rubber coating can be obtained. From the same viewpoint, the heat treatment time is preferably 180 seconds or shorter, more preferably 150 seconds or shorter, and even more preferably 120 seconds or shorter, and may be 0.1 seconds or longer, 0.2 seconds or longer, or 0.5 seconds or longer.

[0106] [Molded body and its manufacturing method] The molded body of the present invention is not particularly limited as long as it contains the coated fiber of the present invention, but because the coated fiber of the present invention has excellent adhesion to the rubber coating, it is particularly preferred to be a molded body containing the coated fiber of the present invention and a rubber component (hereinafter also referred to as a "rubber molded body"). From the viewpoint of maintaining the shape of the rubber, the coated fiber used in the rubber molded body is preferably used as a woven or knitted fabric at least partially containing the coated fiber of the present invention, and more preferably used as a laminate in which a rubber layer is laminated with a reinforcing layer made of a woven or knitted fabric at least partially containing the coated fiber of the present invention.

[0107] Examples of the rubber molded article include rubber products or components thereof, such as tires for automobiles; belts such as conveyor belts and timing belts; hoses such as hoses for automobile liquid fuel, brake oil hoses, and refrigerant hoses; and vibration-isolating rubber. Among these, the rubber molded article is preferably a tire, a belt, a hose, or a component thereof. Examples of components for automobile tires include various components made of composite materials of coated fibers and rubber components, such as belts, carcass plies, and breakers. Among these, the rubber molded article is preferably a tire or a component thereof, and more preferably a tire using the coated fiber of the present invention in the form of a bead tape.

[0108] The rubber molded article is preferably a molded article containing the coated fiber of the present invention and a rubber composition. Examples of the rubber composition include those containing a rubber component and compounding agents commonly used in the rubber industry. The rubber component is not particularly limited, but examples include NR (natural rubber), IR (polyisoprene rubber), BR (polybutadiene rubber), SBR (styrene-butadiene rubber), NBR (nitrile rubber), EPM (ethylene-propylene copolymer rubber), EPDM (ethylene-propylene-non-conjugated diene copolymer rubber), IIR (butyl rubber), halogenated butyl rubber, and CR (chloroprene rubber). Of these, NR, IR, BR, SBR, EPDM, and CR are preferred. These rubber components may be used alone or in combination. For tire applications, rubber components commonly used in the tire industry can be used. Among these, it is preferable to use natural rubber alone, or to use natural rubber in combination with SBR. When natural rubber and SBR are used in combination, the mass ratio of natural rubber to SBR (natural rubber / SBR) is preferably in the range of 20 / 80 to 90 / 10, from the viewpoint of suppressing deterioration in physical properties due to reversion of the rubber.

[0109] Examples of natural rubber include TSR (Technically Specified Rubber), such as SMR (Malaysian TSR), SIR (Indonesian TSR), and STR (Thai TSR), and natural rubber commonly used in the tire industry, such as RSS (Ribbed Smoked Sheet). Natural rubber may also be modified natural rubber, and examples of modified natural rubber include high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, and grafted natural rubber.

[0110] As the SBR, a common SBR used for tires can be used. The styrene content of the SBR is preferably 0.1 to 70 mass%, more preferably 5 to 50 mass%, and even more preferably 15 to 35 mass%. The vinyl content of the SBR is preferably 0.1 to 60 mass%, more preferably 0.1 to 55 mass%. In the present invention, the "styrene content" refers to the content of monomer units derived from styrene.

[0111] The weight-average molecular weight (Mw) of the SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and even more preferably 200,000 to 1,500,000. When the weight-average molecular weight (Mw) is within the above range, both processability and mechanical strength can be achieved. The weight-average molecular weight (Mw) of the SBR is the weight-average molecular weight (Mw) calculated in terms of polystyrene as determined by gel permeation chromatography (GPC). The SBR may be a modified SBR into which a functional group has been introduced, as long as the effects of the present invention are not impaired. Examples of functional groups include amino groups, alkoxysilyl groups, hydroxy groups, epoxy groups, and carboxy groups.

[0112] The rubber composition may further contain a filler in addition to the rubber component. The inclusion of a filler makes it possible to improve physical properties such as mechanical strength, heat resistance, and weather resistance, adjust hardness, and increase the amount of rubber. Examples of fillers include inorganic fillers such as carbon black, silica, clay, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, glass fiber, and glass balloons; and organic fillers such as resin particles, wood flour, and cork powder. These fillers may be used alone or in combination of two or more. Among these, carbon black and silica are preferred from the viewpoint of improving physical properties such as mechanical strength. The shape of the filler may be spherical, fibrous, or amorphous.

[0113] Examples of carbon black include furnace black, channel black, thermal black, acetylene black, and ketjen black. Among these, furnace black is preferred from the viewpoint of improving crosslinking rate and mechanical strength. The average particle size of carbon black is preferably 5 to 100 nm, more preferably 5 to 80 nm, and even more preferably 5 to 70 nm. The average particle size of carbon black can be determined by measuring the particle diameters using a transmission electron microscope and calculating the average value.

[0114] Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred. The average particle size of silica is preferably 0.5 to 200 nm, more preferably 5 to 150 nm, and even more preferably 10 to 100 nm. The average particle size of silica can be determined by measuring the particle diameters using a transmission electron microscope and calculating the average value.

[0115] The content of the filler in the rubber composition is preferably 20 to 150 parts by mass, more preferably 25 to 130 parts by mass, and even more preferably 25 to 110 parts by mass, per 100 parts by mass of the rubber component. When a filler other than silica and carbon black is used as the filler, the content thereof is preferably 20 to 120 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, per 100 parts by mass of the rubber component.

[0116] The rubber composition may further contain a crosslinking agent to crosslink the rubber component. Examples of the crosslinking agent include sulfur, sulfur compounds, oxygen, organic peroxides, phenolic resins, amino resins, quinones, quinone dioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides, organometallic halides, and silane compounds. These crosslinking agents may be used alone or in combination of two or more. From the viewpoint of the mechanical properties of the crosslinked product, the content of the crosslinking agent in the rubber composition is usually 0.1 to 10 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.8 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0117] For example, when the rubber composition contains sulfur or a sulfur compound as a crosslinking agent for crosslinking (vulcanizing) the rubber component, the rubber composition may further contain a vulcanization accelerator. Examples of the vulcanization accelerator include guanidine compounds, sulfenamide compounds, thiazole compounds, thiuram compounds, thiourea compounds, dithiocarbamic acid compounds, aldehyde-amine compounds, aldehyde-ammonia compounds, imidazoline compounds, and xanthate compounds. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator in the rubber composition is typically 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0118] When the rubber composition contains, for example, sulfur, a sulfur compound, or the like as a crosslinking agent for crosslinking (vulcanizing) the rubber component, the rubber composition may further contain a vulcanization aid. Examples of the vulcanization aid include fatty acids such as stearic acid; metal oxides such as zinc oxide; and fatty acid metal salts such as zinc stearate. These vulcanization aids may be used alone or in combination of two or more. The content of the vulcanization aid in the rubber composition is usually 0.1 to 15 parts by mass, and preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0119] When the rubber composition contains silica as a filler, it preferably further contains a silane coupling agent. Examples of silane coupling agents include sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, and chloro compounds. These silane coupling agents may be used alone or in combination of two or more. The content of the silane coupling agent in the rubber composition is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 15 parts by mass, per 100 parts by mass of silica. When the content of the silane coupling agent is within the above range, dispersibility, coupling effect, reinforcement, and the like are improved.

[0120] The rubber composition may contain, as needed, softeners such as silicone oil, aromatic oil, TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), paraffin oil, naphthenic oil, or other process oils; aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, C9 resins, rosin resins, coumarone-indene resins, phenolic resins, or other resin components, for the purpose of improving processability, fluidity, etc., within a range that does not impair the effects of the present invention. When the rubber composition contains a softener, the content thereof is preferably less than 50 parts by mass per 100 parts by mass of the rubber component.

[0121] The rubber composition may contain additives such as antioxidants, waxes, antioxidants, lubricants, light stabilizers, scorch inhibitors, processing aids, colorants such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, UV absorbers, mold release agents, foaming agents, antibacterial agents, antifungal agents, and fragrances, as needed, to improve weather resistance, heat resistance, and oxidation resistance, as long as the effects of the present invention are not impaired. Examples of antioxidants include hindered phenol compounds, phosphorus compounds, lactone compounds, and hydroxyl compounds. Examples of antioxidants include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, and phosphorus compounds. These additives may be used alone or in combination.

[0122] As a method for producing a rubber molded article, for example, the coated fiber of the present invention is embedded in an unvulcanized rubber composition and the rubber composition is vulcanized to obtain a molded article in which the fiber and the rubber component are bonded via a coating containing one or more selected from the group consisting of the fiber treatment agent of the present invention and reaction products of the fiber treatment agent.

[0123] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to such examples. [Production of (A) Modified Conjugated Diene Rubber] Production Example 1: Production of Modified Conjugated Diene Rubber (A-1) A thoroughly dried 5 L autoclave was purged with nitrogen, and 1,260 g of hexane and 90.0 g of n-butyllithium (17 mass % hexane solution) were charged. The temperature was raised to 50°C, and then 1,260 g of 1,3-butadiene was gradually added under stirring conditions while controlling the polymerization temperature to 50°C, and polymerization was carried out for 1 hour. Methanol was then added to terminate the polymerization reaction, yielding a polymer solution. Water was added to the obtained polymer solution, and the mixture was stirred. The polymer solution was washed with water. After stirring was stopped, separation of the polymer solution phase and the aqueous phase was confirmed, and the water was then separated. The washed polymer solution was vacuum dried at 70°C for 24 hours to yield unmodified liquid polybutadiene (A'-1). Subsequently, 500 g of the obtained unmodified liquid polybutadiene (A'-1) was charged into a 1 L autoclave that had been purged with nitrogen, and 25 g of maleic anhydride and 0.5 g of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (trade name "Nocrac 6C", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added, followed by a reaction at 170°C for 24 hours to obtain a maleic anhydride-modified liquid polybutadiene. 8.2 g of methanol was added to 525 g of the obtained maleic anhydride-modified liquid polybutadiene, and the mixture was reacted at 80°C for 6 hours to obtain a monomethyl maleate-modified liquid polybutadiene (modified conjugated diene rubber (A-1)).

[0124] The methods for measuring and calculating the properties of the (A) modified conjugated diene rubber are as follows. The results are shown in Table 1.

[0125] <Method of measuring weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn)> The Mw, Mn, and Mw / Mn of the (A) modified conjugated diene rubber were determined as polystyrene equivalent values ​​by gel permeation chromatography (GPC). The measurement device and conditions were as follows: Device: GPC device "GPC8020" manufactured by Tosoh Corporation Separation column: "TSKgel G4000HXL" manufactured by Tosoh Corporation Detector: "RI-8020" manufactured by Tosoh Corporation Eluent: tetrahydrofuran Eluent flow rate: 1.0 ml / min Sample concentration: 5 mg / 10 ml Column temperature: 40°C

[0126] <Method for measuring melt viscosity at 38°C> (A) The melt viscosity of the modified conjugated diene rubber at 38°C was measured using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

[0127] <Method for measuring glass transition temperature> (A) 10 mg of modified conjugated diene rubber was placed in an aluminum pan, and a thermogram was measured by differential scanning calorimetry (DSC) at a heating rate of 10°C / min. The value at the peak top of DDSC, which means the derivative of DSC, was taken as the glass transition temperature.

[0128] <Method for Calculating the Average Number of Hydrogen-Bonding Functional Groups per Molecule> The average number of hydrogen-bonding functional groups per molecule of the (A) modified conjugated diene rubber was calculated from the equivalent weight (g / eq) of the hydrogen-bonding functional groups of the (A) modified conjugated diene rubber and the number average molecular weight (Mn) in terms of polystyrene, using the following formula: Average number of hydrogen-bonding functional groups per molecule = [(number average molecular weight (Mn)) / (molecular weight of styrene units) × (average molecular weight of conjugated diene and other monomer units other than conjugated diene, if contained as necessary)] / (equivalent weight of hydrogen-bonding functional groups) The method for calculating the equivalent weight of the hydrogen-bonding functional groups can be appropriately selected depending on the type of hydrogen-bonding functional group.

[0129] The average number of hydrogen-bonding functional groups per molecule of the monomethyl maleate-modified liquid polybutadiene was calculated by determining the acid value of the monomethyl maleate-modified liquid polybutadiene and calculating the equivalent weight (g / eq) of the hydrogen-bonding functional groups from the acid value. After the modification reaction, the sample was washed four times with methanol (5 mL per 1 g of sample) to remove impurities such as antioxidants, and then dried under reduced pressure at 80°C for 12 hours. After the pretreatment, 3 g of the sample was dissolved in 180 mL of toluene and 20 mL of ethanol, and then neutralized with a 0.1 N potassium hydroxide solution in ethanol. The acid value was calculated using the following formula: Acid value (mg KOH / g) = (A - B) x F x 5.611 / S A: Amount (mL) of 0.1 N potassium hydroxide ethanol solution added required for neutralization B: Amount (mL) of 0.1 N potassium hydroxide ethanol solution added to a blank containing no sample F: Potency of 0.1 N potassium hydroxide ethanol solution S: Mass (g) of weighed sample

[0130] From the acid value, the mass of hydrogen-bonding functional groups contained per gram of monomethyl maleate-modified liquid polybutadiene was calculated using the following formula, and the mass other than functional groups (polymer main chain mass) contained per gram of monomethyl maleate-modified liquid polybutadiene was also calculated. The equivalent weight (g / eq) of the hydrogen-bonding functional group was then calculated using the following formula: [Mass of hydrogen-bonding functional group per gram] = [Acid value] / [56.11] × [Molecular weight of hydrogen-bonding functional group] / 1000 [Mass of polymer main chain per gram] = 1 - [Mass of hydrogen-bonding functional group per gram] [Equivalent weight of hydrogen-bonding functional group] = [Mass of polymer main chain per gram] / ([Mass of hydrogen-bonding functional group per gram] / [Molecular weight of hydrogen-bonding functional group]).

[0131]

[0132] <Preparation of Emulsion> Preparation Example 1: Preparation of Emulsion (E-1) of Modified Conjugated Diene Rubber (A-1) 60 g of the modified conjugated diene rubber (A-1) and 3.6 g of a nonionic surfactant (HLB value = 13.9, trade name "Adekataol UA-90N", ADEKA Corporation) as a surfactant (D) were added and stirred for 5 minutes. Subsequently, 86.4 g of a 0.15 mol / L aqueous ammonia solution was added little by little while stirring, thereby obtaining an emulsion (E-1) in which oil droplets containing the modified conjugated diene rubber (A-1) were dispersed in water.

[0133] <Production of fiber treatment agents and coated fibers> Examples 1 to 5 and Comparative Examples 1 and 2 Fiber treatment agents were prepared by mixing emulsion (E-1), a crosslinking agent, and water to obtain the compositions shown in Table 2. Details of the crosslinking agents shown in Table 2 are as follows. (B-1) Isocyanate compound: lactam-blocked diphenylmethane diisocyanate (trade name "Elastron BN-27", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., solid content concentration 30% by mass), dissociation temperature of blocking agent: 180°C or higher (B-2) Isocyanate compound: methyl ethyl ketone oxime-blocked diphenylmethane diisocyanate (trade name "Elastron BN-69", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., solid content concentration 40% by mass), dissociation temperature of blocking agent: 120°C or higher (B-3) Isocyanate compound: oxime-blocked tolylene diisocyanate (trade name "Meikanate TP-10", manufactured by Meisei Chemical Industry Co., Ltd., solid content concentration 44% by mass), dissociation temperature of blocking agent: 120°C or higher (B'-4) Isocyanate compound as a comparative component: a blocking agent adduct of hexamethylene diisocyanate (trade name "SU268-A", manufactured by Meisei Chemical Industry Co., Ltd., solid content concentration 30% by mass); (C) Epoxy compound: sorbitol polyglycidyl ether (trade name "Denacol EX-614B", manufactured by Nagase ChemteX Corporation, number of epoxy groups per molecule: 4). Next, the fibers shown in Table 2 were immersed in the obtained fiber treatment agent, and the liquid was squeezed out with a roller. Thereafter, the obtained fibers were dried at 140°C for 60 seconds, further heat-treated at 200°C for 60 seconds, and then wound up to produce coated fibers in which the fibers were coated with a coating containing one or more selected from the group consisting of fiber treatment agents and reaction products of the fiber treatment agents. The details of the fibers listed in Table 2 are as follows. Vinylon fiber 1: Polyvinyl alcohol fiber spun yarn, cotton count 5 Polyester fiber: Polyester fiber spun yarn, cotton count 5 Vinylon fiber 2: Polyvinyl alcohol fiber filament, total fineness 1330 dtex

[0134] <Amount of Coating Adhesion> A 100 m length of fiber was sampled before application of the fiber treatment agent, and the fiber was dried at 105°C for 4 hours, after which its mass was measured, and the measured value was recorded as the mass before coating treatment. Next, the fiber was applied with the fiber treatment agent by the method described in each example, and after drying and heat treatment, the same length of fiber was sampled, and the same length of fiber was dried at 105°C for 4 hours, after which its mass was measured, and the measured value was recorded as the mass after coating treatment. The amount of coating adhesion per 100 parts by mass of fiber before application of the fiber treatment agent was calculated as [(mass after coating treatment) - (mass before coating treatment)] x 100 / (mass before coating treatment).

[0135] <Rubber Adhesion Strength> Evaluation sheets were prepared for the coated fibers prepared in each example by the method described below. The force (N / 25.4 mm) required to peel the coated fiber from the rubber was then measured using a T-type testing machine and evaluated as rubber adhesion strength. The results are shown in Table 2. The evaluation results for rubber adhesion strength indicate that the higher the numerical value, the stronger the adhesion between the coated fiber and rubber. The evaluation sheets were prepared as follows.

[0136] Preparation of Evaluation Sheet The coated fibers prepared in each example were arranged and fixed on masking tape in a curtain-like manner so that the fibers did not overlap, and then this was overlapped with an unvulcanized rubber composition containing NR / SBR rubber as the main component prepared according to the following formulation (hereinafter also referred to as "NR / SBR unvulcanized rubber"; width 25.4 mm, length 240 mm). The length of the overlapped portion of the coated fiber and NR / SBR unvulcanized rubber was 190 mm. Next, the coated fibers were heated at 150°C and a pressure of 20 kg / cm. ２ The mixture was press-vulcanized for 30 minutes under the conditions of 1.0 to 1.5° C. for 30 minutes to prepare a sheet for evaluation.

[0137] [Composition of NR / SBR unvulcanized rubber] NR rubber: 50 parts by mass SBR rubber: 50 parts by mass Filler (carbon black): 45 parts by mass Vulcanizing agent (sulfur powder): 3.5 parts by mass Vulcanization aid (zinc oxide, stearic acid): 6 parts by mass Vulcanization accelerator (thiazole type): 1 part by mass

[0138]

[0139] As is clear from the results of Examples 1 to 5 and Comparative Examples 1 and 2 shown in Table 2, the fiber treatment agent of the present invention can provide coated fibers with excellent adhesion to the rubber coating. Furthermore, when spun yarn is used, a portion of the fibers constituting the spun yarn deviates from the main axis of the yarn and is exposed on the surface of the fiber, thereby enabling the development of higher adhesive strength.

[0140] Comparative Example 3: A two-component fiber treatment agent was prepared without mixing the crosslinking agent and water with emulsion (E-1) to achieve the composition shown in Table 3. Specifically, a fiber shown in Table 3 was first immersed in the fiber treatment agent consisting of the crosslinking agent and water shown in Table 3, and then the liquid was squeezed out with a roller. The resulting fiber was then dried at 140°C for 60 seconds and further heat-treated at 200°C for 60 seconds. The resulting fiber was then immersed in the fiber treatment agent consisting of emulsion (E-1), squeezed out with a roller, dried at 140°C for 60 seconds, and further heat-treated at 200°C for 60 seconds. The resulting fiber was wound up to produce a coated fiber coated with a coating material containing one or more selected from the group consisting of two-component fiber treatment agents and reaction products of the fiber treatment agents. The amount of coating attached to the resulting coated fiber was measured using the method described above, and rubber adhesion was evaluated. The results, along with those of Example 1, are shown in Table 3.

[0141]

[0142] As is clear from the results of Example 1 and Comparative Example 3 shown in Table 3, by treating with the one-component fiber treating agent of the present invention, it is possible to obtain coated fibers that have excellent adhesion to the rubber coating.

Claims

1. A fiber treatment agent comprising: (A) a modified conjugated diene rubber; (B) an isocyanate compound having a cyclic structure and having two or more groups per molecule of one or more types selected from the group consisting of isocyanate groups and blocked isocyanate groups; and (C) an epoxy compound having two or more epoxy groups per molecule.

2. The fiber treatment agent according to claim 1, wherein the modified conjugated diene rubber (A) has a number average molecular weight (Mn) of 1,000 or more and 120,000 or less.

3. The fiber treatment agent according to claim 1, wherein the modified conjugated diene rubber (A) has monomer units derived from one or more species selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, and farnesene.

4. The fiber treatment agent according to claim 1, wherein the cyclic structure contained in component (B) is an aromatic ring.

5. A coated fiber comprising a fiber and a coating covering the surface of the fiber, wherein the coating contains one or more members selected from the group consisting of the fiber treatment agent according to any one of claims 1 to 4 and reaction products of the fiber treatment agent.

6. The coated fiber according to claim 5, wherein the reaction product of the fiber treatment agent is at least one selected from the group consisting of (A) modified conjugated diene rubbers bonded together via a crosslinking agent and (A) modified conjugated diene rubbers bonded to fibers via a crosslinking agent.

7. The coated fiber according to claim 5, wherein the fiber is one or more fibers selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers.

8. The coated fiber according to claim 5, wherein the amount of the coating applied is 5 to 15 parts by mass per 100 parts by mass of the fiber used as the raw material.

9. The coated fiber of claim 5, wherein the fiber is a spun yarn.

10. A molded article comprising the coated fiber of claim 5.

11. A method for producing the coated fiber according to claim 5, wherein the fiber treatment agent is applied to the fiber, and then the fiber is heated to form the coating.

12. The method for producing a coated fiber according to claim 11, wherein the fiber is one or more fibers selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers.

13. The method for producing coated fibers according to claim 11, wherein the amount of the coating applied is 5 to 15 parts by mass per 100 parts by mass of the fibers used as raw materials.

14. The method of producing a coated fiber according to claim 11, wherein the fiber is a spun yarn.

15. A method for producing a molded article using a coated fiber produced by the method for producing a coated fiber according to claim 11.

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