WO2025177998A1 - Fiber treatment agent, coated fiber, shaped body, and method for manufacturing coated fiber and shaped body - Google Patents

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

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.

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 order to fully utilize the excellent physical properties of rubber in these products (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 Document 1 and Patent Document 2).

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

Japanese Patent Application Publication No. 54-4976 Japanese Patent Application Publication No. 58-2370 International Publication No. 2023/085413

The reinforcing fibers described in Patent Document 3 have good adhesive strength to the rubber substrate (hereinafter also referred to as "substrate rubber"), but in order to further improve the durability of rubber products, further improvements in adhesion to the substrate rubber are required.

The present invention was made in consideration of the above problems, and aims to provide a fiber treatment agent that can produce coated fibers that have excellent adhesion to rubber substrates even without containing resorcinol or formaldehyde, a coated fiber that uses 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.

As a result of extensive research to solve the above-mentioned problems, the inventors discovered that by using a fiber treatment agent with a specific composition, coated fibers with excellent adhesion to the rubber coating can be obtained without containing resorcinol or formaldehyde, leading to the completion of the present invention.

That is, the present invention relates to the following [1] to [14].
[1] (A) a modified conjugated diene rubber,
(B) an isocyanate compound having a cyclic structure and having two or more groups selected from the group consisting of an isocyanate group and a blocked isocyanate group per molecule;
(C) an epoxy compound having two or more epoxy groups in one molecule;
A fiber treatment agent comprising:
[2] The fiber treating agent according to the above [1], wherein the number average molecular weight (Mn) of the modified conjugated diene rubber (A) is 1,000 or more and 120,000 or less.
[3] The fiber treatment agent according to the above [1] or [2], 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 treatment agent according to any one of the above [1] to [3], wherein the cyclic structure contained in the component (B) is an aromatic ring.
[5] A fiber and a coating that coats the surface of the fiber,
A coated fiber, wherein the coating comprises at least one selected from the group consisting of the fiber treating agent according to any one of [1] to [4] above and a reaction product of the fiber treating agent.
[6] The coated fiber according to [5] above, 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 and fibers bonded together via a crosslinking agent.
[7] The coated fiber according to [5] or [6] 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.
[8] The coated fiber according to any one of [5] to [7] above, wherein the amount of the coating attached is 5 to 15 parts by mass per 100 parts by mass of the fiber used as the raw material.
[9] The covered fiber according to 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,
A method for producing a coated fiber, comprising: applying 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 attached 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 covered fiber according to any one of [11] to [13] above, 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 any one of [11] to [14] above.

The present invention provides a fiber treatment agent that can produce coated fibers that have excellent adhesion to rubber substrates, even without containing resorcinol or formaldehyde; coated fibers that use the fiber treatment agent and a method for producing the same; and molded articles that include the coated fibers and a method for producing the same.

[Fiber treatment agent]
The fiber treating agent of the present invention contains (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 group 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").

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 have excellent adhesion to the rubber coating. 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 can be covalently bonded to each other and to the (A) modified conjugated diene rubber and the fiber via covalent bonds with 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 coating, the (A) modified conjugated diene rubber is less likely to be absorbed by the rubber coating, and the coated fiber exhibits excellent adhesion to the rubber coating.
Furthermore, the isocyanate compound (B) 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 compared to conventional fiber treatment agents. Although the reason for this is unclear, it is presumed that one factor is the increased rigidity of the molecule due to the presence of the cyclic structure.

The fiber treatment agent of the present invention is not particularly limited in its 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 ease of handling, the fiber treatment agent of the present invention preferably contains a liquid medium such as a solvent or a dispersion medium, and each component is preferably in a state of being dissolved or dispersed in the liquid medium before being applied to the fiber.
The liquid medium that can be contained in the fiber treatment agent of the present invention is not particularly limited, but from the viewpoint of ease of handling, water is preferred.
Each component contained in the fiber treating agent of the present invention will be described below.

<(A) Modified conjugated diene rubber>
(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 introduce a functional group other than a vinyl group contained in the conjugated diene unit.
The modified conjugated diene rubber (A) preferably contains 50 mol % or more of conjugated diene units in all monomer units in the modified conjugated diene rubber (A).
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.

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 the monomer other than the conjugated diene include copolymerizable ethylenically unsaturated monomers and aromatic vinyl compounds.
Examples of the ethylenically unsaturated monomer 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, and divinylbenzene.
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.

The modified conjugated diene rubber (A) is not particularly limited as long as it has a functional group in a portion thereof, but it is preferably one having a hydrogen-bonding functional group, and more preferably one containing a conjugated diene unit in at least a portion of the polymer chain and having a hydrogen-bonding functional group in a side chain or at the end of the polymer chain.
The (A) modified conjugated diene rubber has hydrogen-bonding functional groups, which interact with the rubber substrate and the fiber, thereby more firmly adhering them to each other. Furthermore, when the (A) modified conjugated diene rubber and the rubber substrate are vulcanized to form covalent bonds, a strong cohesive force is generated, further improving adhesion to the rubber substrate. Furthermore, when hydrophilic fibers are used as the fibers, the hydrogen-bonding functional groups of the (A) modified conjugated diene rubber form hydrogen bonds with the hydrophilic fibers, which is thought to improve adhesion.

In this specification, the term "hydrogen bond" refers to the bonding interaction formed between an electrically positively polarized hydrogen atom (donor) bonded to an atom with a high electronegativity (O, N, S, etc.), and an electrically negative atom (acceptor) with a lone pair of electrons.

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.

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 radically polymerizable compounds having hydrogen-bonding functional groups and silane compounds having hydrogen-bonding functional groups, and more preferably a functional group derived from a radically polymerizable compound having a hydrogen-bonding functional group.

The radically polymerizable compound having a hydrogen-bonding functional group is not particularly limited, as long as it has both a hydrogen-bonding functional group and a reactive multiple bond in the molecule. Specific examples include aldehydes having a reactive multiple bond, acetalized products of such aldehydes; monocarboxylic acids having a reactive multiple bond, salts of such monocarboxylic acids, esterified products of such monocarboxylic acids, amide compounds of such monocarboxylic acids, and acid anhydrides of such monocarboxylic acids; dicarboxylic acids having a reactive multiple bond, salts of such dicarboxylic acids, esterified products of such dicarboxylic acids, amide compounds of such dicarboxylic acids, imide compounds derived from such dicarboxylic acids, and acid anhydrides of such dicarboxylic acids; and amine compounds having a reactive multiple bond. These radically polymerizable compounds may be used alone or in combination of two or more.

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. 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.
In addition, when the aldehyde has cis-trans isomers, it includes both the cis and trans isomers.

Among acetalized aldehydes having reactive multiple bonds, acetalized aldehydes having reactive carbon-carbon double bonds include, for example, acetalized aldehydes, specifically, 3-(1,3-dioxalan-2-yl)-3-methyl-1-propene, which is an acetalized 2-methyl-3-butenal, and 3-(1,3-dioxalan-2-yl)-2-methyl-1-propene, which is an acetalized 3-methyl-3-butenal.

Among aldehydes having reactive multiple bonds and acetalized products of such aldehydes, aldehydes having reactive carbon-carbon triple bonds and acetalized products thereof include, for example, aldehydes having carbon-carbon triple bonds such as propioaldehyde, 2-butyn-1-al, and 2-pentyn-1-al; acetalized products of such aldehydes, etc.

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 due to their good reactivity during copolymerization.

Examples of monocarboxylic acids having a reactive multiple bond, salts of the monocarboxylic acid, esters of the monocarboxylic acid, amide compounds of the monocarboxylic acid and acid anhydrides of the monocarboxylic acid include (meth)acrylic acid, sodium salts of (meth)acrylic acid, potassium salts 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-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate ...propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxypropyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxypropyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, Vinyl acrylate, 2-(trifluoromethyl)acrylic acid, methyl 2-trifluoromethylacrylate, ethyl 2-trifluoromethylacrylate, propyl 2-trifluoromethylacrylate, 2-butyl 2-trifluoromethylacrylate, 2-hydroxyethyl 2-trifluoromethylacrylate, vinyl 2-trifluoromethylacrylate, methyl cinnamate, vinyl cinnamate, methyl crotonate, vinyl crotonate, 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, 3,3-dimethyl-4-pentenoate methyl 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, ethyl 3-methyl-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, Examples of the carboxylic acid include carboxylic acids having a reactive carbon-carbon double bond, salts of the carboxylic acid, esterified products of the carboxylic acid, and acid anhydrides of the carboxylic acid, such as 3-methyl-3-butenoic anhydride, 4-pentenoic anhydride, 2-methyl-4-pentenoic anhydride, 5-hexenoic anhydride, 3,3-dimethyl-4-pentenoic anhydride, 7-octenoic anhydride, trans-3-pentenoic anhydride, trans-4-decenoic anhydride, and 10-undecenoic anhydride; and carboxylic acids having a reactive carbon-carbon triple bond and esterified products of the carboxylic acid, such as propiolic acid, methyl propiolate, ethyl propiolate, vinyl propiolate, tetrolic acid, methyl tetrolate, ethyl tetrolate, and vinyl tetrolate.
In this specification, "(meth)acrylic acid" is a general term for "acrylic acid" and "methacrylic acid."

Dicarboxylic acids having reactive multiple bonds, salts of the dicarboxylic acids, esters of the dicarboxylic acids, amide compounds of the dicarboxylic acids, imide compounds derived from the dicarboxylic acids, and acid anhydrides of the dicarboxylic acids include, for example, dicarboxylic acids having reactive multiple bonds such as maleic acid, 2,3-dimethylmaleic acid, fumaric acid, citraconic acid, itaconic acid, etc.; salts of dicarboxylic acids having reactive multiple bonds such as sodium maleate, potassium maleate, etc.; maleic acid esters (for example, methyl maleate, dimethyl maleate, etc.), fumaric acid esters (for example, methyl fumarate, dimethyl fumarate, etc.), citraconic acid esters (for example, Examples of suitable dicarboxylic acids include esters of dicarboxylic acids having reactive multiple bonds, such as methyl citraconic acid, dimethyl citraconic acid, and itaconic acid esters (e.g., methyl itaconate, dimethyl itaconate); amide compounds of dicarboxylic acids having reactive multiple bonds, such as maleic acid amide, fumaric acid amide, citraconic acid amide, and itaconic acid amide; imide compounds derived from dicarboxylic acids having reactive multiple bonds, such as maleic acid imide, fumaric acid imide, citraconic acid imide, and itaconic acid imide; and anhydrides of dicarboxylic acids having reactive multiple bonds, such as maleic anhydride, 2,3-dimethylmaleic anhydride, citraconic anhydride, and itaconic anhydride.

As for the monocarboxylic acids having a reactive multiple bond, salts of the monocarboxylic acids, esters of the monocarboxylic acids, amide compounds of the monocarboxylic acids, and monocarboxylic acid anhydrides, as well as the dicarboxylic acids having a reactive multiple bond, salts of the dicarboxylic acids, esters of the dicarboxylic acids, amide compounds of the dicarboxylic acids, imide compounds derived from the dicarboxylic acids, and acid anhydrides of the dicarboxylic acids, compounds having a reactive carbon-carbon double bond are preferred. Among these, 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 due to their good reactivity during copolymerization.

Among 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, and 4-vinyloxyaniline. Of these, allylamine, 3-butenylamine, and 4-pentenylamine are preferred due to their favorable reactivity during copolymerization.

Examples of silane compounds having hydrogen-bonding functional groups 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 3-mercaptopropylethoxydimethylsilane.

From the viewpoint of improving adhesion to the adherend rubber, 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 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, still 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 still more preferably 3 to 10, on average per molecule.
The average number of hydrogen-bonding functional groups per molecule of the modified conjugated diene rubber (A) can be calculated by the method described in the examples.

(A) Examples of methods for obtaining modified conjugated diene rubber include a method of adding a modifying compound to a polymer of conjugated diene (hereinafter also referred to as "production method (1)"), a method of oxidizing a polymer of 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 unmodified conjugated diene having the active polymerization terminal before adding a polymerization terminator (hereinafter also referred to as "production method (4)").

(A) Method for producing modified conjugated diene rubber (1)
The production method (1) is a method in which a modifying compound is added to a polymer of a conjugated diene, that is, 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, or the like.
Of the above methods, the solution polymerization method is preferred as the method for producing the unmodified conjugated diene rubber.

As the solution polymerization method, a known method or a method equivalent to a known method 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, in the presence of a polar compound as needed.
Examples of the solvent used in the solution polymerization method 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.

Examples of active metals capable of anion polymerization 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. Of these, alkali metals and alkaline earth metals are preferred, with alkali metals being more preferred.

As the anionically polymerizable active metal compound, an organic alkali metal compound is preferred.
Examples of organic alkali metal compounds 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; sodium naphthalene, potassium naphthalene, etc. 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 set depending on the melt viscosity, molecular weight, etc. of the target 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.

In anionic polymerization, polar compounds are generally 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.

The solution polymerization temperature is usually -80 to +150°C, preferably 0 to 100°C, and more preferably 10 to 90°C. The polymerization method may be either batch or continuous.

The solution polymerization reaction can be terminated by adding a polymerization terminator. Examples of polymerization terminators include alcohols such as methanol and isopropanol. The resulting polymerization reaction liquid can be poured into a poor solvent such as methanol to precipitate the polymerized product, or the polymerization reaction liquid can be washed with water, separated, and then dried to isolate the unmodified conjugated diene rubber.

As the emulsion polymerization method, a known method or a method equivalent to a known method can be applied. Specifically, for example, a method can be applied in which a monomer containing a predetermined amount of conjugated diene is emulsified and dispersed in the presence of an emulsifier, and emulsion polymerized using a radical polymerization initiator.
Examples of emulsifiers include salts of long-chain fatty acids having 10 or more carbon atoms, rosinate salts, etc. Examples of salts of long-chain fatty acids 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.
As the dispersion solvent, water is usually used, and it may contain a water-soluble organic solvent such as methanol or ethanol to the extent that stability during polymerization is not impaired.
Examples of the radical polymerization initiator 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.

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

The emulsion polymerization reaction can be terminated by adding a polymerization terminator. Examples of polymerization terminators include amine compounds such as isopropylhydroxylamine, diethylhydroxylamine, and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; and sodium nitrite.

After the polymerization reaction is stopped, an antioxidant may be added as needed.
After the polymerization reaction is stopped, unreacted monomers are removed from the obtained latex as needed. Then, the polymer is coagulated using a salt such as sodium chloride, calcium chloride, or potassium chloride as a coagulant, and, if necessary, an acid such as nitric acid or sulfuric acid is added to adjust the pH of the coagulation system to a predetermined value. The polymer is then recovered by separating the dispersion solvent. The polymer is then washed with water, dehydrated, and dried to obtain an unmodified conjugated diene rubber. During the coagulation, the latex may be mixed with an extender oil previously emulsified and dispersed, if needed, and the oil-extended unmodified conjugated diene rubber may be recovered.

(Modifying compound used in production method (1))
The modifying compound used in the production method (1) is not particularly limited, but from the viewpoint of improving adhesion to the rubber substrate, it is preferable to use a compound having a hydrogen-bonding functional group. Examples of the hydrogen-bonding functional group include the same as those described above, and preferred embodiments are also the same.
As the modified compound having a hydrogen-bonding functional group, the radical polymerizable compound having a hydrogen-bonding functional group, the silane compound having a hydrogen-bonding functional group, and the like exemplified above can be used.
These modifying compounds having a hydrogen-bonding functional group may be used alone or in combination of two or more.

The amount of the modifying compound used in 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 unmodified conjugated diene rubber.

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.

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, silane compounds, etc., and a radical generator used as needed are heated in the presence or absence of an organic solvent. There are no particular limitations on the radical generator used, and commercially available organic peroxides, azo compounds, hydrogen peroxide, etc. can be used.
The reaction temperature is usually preferably 0 to 200°C, more preferably 50 to 200°C.
Examples of organic solvents include hydrocarbon solvents, halogenated hydrocarbon solvents, etc. Among these, hydrocarbon solvents such as n-butane, n-hexane, n-heptane, cyclohexane, benzene, toluene, and xylene are preferred.

Furthermore, 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. Specifically, for example, maleic anhydride may be grafted onto an unmodified conjugated diene rubber obtained by living anionic polymerization, followed by reaction with a compound containing a hydroxyl group, such as 2-hydroxyethyl methacrylate or methanol, or a compound such as water.

Furthermore, from the viewpoint of suppressing side reactions, an antioxidant may be added when carrying out a reaction of adding a modifying compound to an unmodified conjugated diene rubber, a modified conjugated diene rubber (a conjugated diene rubber into which a hydrogen-bonding functional group is introduced, obtained by the above-mentioned method), etc. As the antioxidant, commercially available ones 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.

(A) Method for producing modified conjugated diene rubber (2)
The production method (2) is a method in which a polymer of a conjugated diene (unmodified conjugated diene rubber) is oxidized.
The production method (2) includes a method of oxidizing an unmodified conjugated diene rubber as a raw material to obtain an oxidized conjugated diene rubber having an oxygen-containing functional group or bond generated in the molecule by the oxidation reaction, such as a hydroxy group, an aldehyde group, a carbonyl group, a carboxy group, an ether bond, etc.
The unmodified conjugated diene rubber can be obtained by the same method as in the production method (1).

Methods for oxidizing unmodified conjugated diene rubber include, for example, a method of heat-treating unmodified conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (hereinafter also referred to as "production method (2-1)"), and a method of activating the unmodified conjugated diene rubber by irradiating it with light of a wavelength absorbed by the unmodified conjugated diene rubber and causing it to react with oxygen (hereinafter also referred to as "production method (2-2)"). Of these, the method of heat-treating unmodified conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (production method (2-1)) is preferred.

Method for producing oxidized conjugated diene rubber (2-1)
The production method (2-1) is a method in which an unmodified conjugated diene rubber is heat-treated at a temperature equal to or higher than the oxidation temperature 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 is oxidized, but from the viewpoint of increasing the reaction rate of the oxidation and improving productivity, the heat treatment temperature is preferably 150° C. or higher, more preferably 170° C. or higher, and even more preferably 190° C. or higher. When the unmodified conjugated diene rubber is oxidized on the surface of the hydrophilic fiber as described below, from the viewpoint of preventing deterioration of the fiber, the heat treatment temperature is preferably 240° C. or lower, and more preferably 220° C. or lower.
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, but is preferably 30 minutes or less, more preferably 20 minutes or less. From the viewpoint of sufficiently oxidizing the unmodified conjugated diene rubber, the heat treatment time is preferably 1 second or more, more preferably 10 seconds or more, and even more preferably 30 seconds or more.

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 the thermal radical generator include peroxides, azo compounds, redox initiators, etc. 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.

Method for producing oxidized conjugated diene rubber (2-2)
The production method (2-2) is a method in which the unmodified conjugated diene rubber is activated by irradiation with light having a wavelength that the unmodified conjugated diene rubber absorbs, and then reacted with oxygen.
The 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 absorbed by the unmodified conjugated diene rubber to cause a radical reaction, but ultraviolet light, which is strongly absorbed by the unmodified conjugated diene rubber, is preferred.

Furthermore, by adding a photoradical generator to unmodified conjugated diene rubber, the amount of light exposure required for the oxidation reaction can be reduced.

(A) Method for producing modified conjugated diene rubber (3)
The production method (3) is a method of copolymerizing a conjugated diene with a radically polymerizable compound having a hydrogen-bonding functional group.
The production method (3) includes a method in which a conjugated diene and a radically polymerizable compound having a hydrogen-bonding functional group are randomly copolymerized, block copolymerized, or graft copolymerized by a known method.

(Radically 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. Specifically, the radical polymerizable compounds having a hydrogen-bonding functional group exemplified above can be used.

(A) Method for producing modified conjugated diene rubber (4)
The production method (4) is a method in which a modifying compound capable of reacting with the active polymerization terminals is added to a polymer of an unmodified conjugated diene having an active polymerization terminal (unmodified conjugated diene rubber) before adding a polymerization terminator.
The unmodified conjugated diene rubber having a polymerization active terminal can be obtained by the same method as in the production method (1).
Examples of the modifying compound that can be used in the 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.

In the production method (4), the amount of the modifying compound used is preferably 0.01 to 100 molar equivalents relative to the organic alkali metal compound, for example, when the polymerization is carried out using an 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, a 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.

There are no particular restrictions on the method for producing the (A) modified conjugated diene rubber, but from the standpoint of productivity, production by production method (1), (2), or (3) is preferred, production by production method (1) or (3) is more preferred, and production by production method (1) is even more preferred.

((A) Physical Properties of 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, still 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 modified conjugated diene rubber (A). Here, "different types of modified conjugated diene rubber (A)" means that the modified conjugated diene rubbers are different in 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.

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, still 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, still 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), 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.

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, still 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, determined by GPC measurement.

The modified conjugated diene rubber (A) is preferably liquid from the viewpoint of adhesiveness to fibers.
In this specification, "liquid" means that the melt viscosity of the (A) modified conjugated diene rubber at 38°C is 4,000 Pa s or less. From the viewpoint of improving adhesion 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 adhesion to fibers.
The melt viscosity of the modified conjugated diene rubber (A) 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.

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 the rubber easier to handle.
The glass transition temperature (Tg) of the modified conjugated diene rubber (A) can be determined by the method described in the examples.

The vinyl content of the modified conjugated diene rubber (A) 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 this range, adhesion to the adherend rubber is improved.
In this specification, the term "vinyl content" refers to 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 can be calculated using ^1H -NMR from the integral ratio of the signal derived from conjugated diene units bonded via 1,2-bonds or 3,4-bonds to the signal derived from conjugated diene units bonded via 1,4-bonds.

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

The content of (A) modified conjugated diene rubber in the fiber treatment agent of the present invention before it is applied 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 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 (A) modified conjugated diene rubber is within the above range, excellent adhesion to the adherend rubber can be obtained while preventing the viscosity of the fiber treatment agent before it is applied to fibers from becoming extremely high.

<(B) Isocyanate Compound Having a Cyclic Structure and Two or More Groups Selected from the Group Consisting of Isocyanate Groups and Blocked Isocyanate Groups in Each Molecule>
The isocyanate compound (B) is not particularly limited as long as it is an isocyanate compound having two or more groups of one or more types selected from the group consisting of an isocyanate group and a blocked isocyanate group in one molecule.
In the present invention, the blocked isocyanate group that the component (B) may have is a group formed by adding a blocking agent to an isocyanate group.
The number of one or more groups selected from the group consisting of an isocyanate group and a blocked isocyanate group that the isocyanate compound (B) has in one molecule is 2 or more, and is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less, from the viewpoint of improving adhesion to the adherend rubber.

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 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.

The isocyanate compound (B) contained in the fiber treatment agent of the present invention has a cyclic structure in the molecule, and is preferably represented by the following general formula (1):
X-R-X (1)
(In the formula, 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, an aliphatic ring, etc. Among these, the isocyanate compound (B) preferably contains an aromatic ring as the cyclic structure.
Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, etc. Among these, a benzene ring is preferred.
The number of cyclic structures that the isocyanate compound (B) has in one molecule is 1 or more, preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less, from the viewpoint of improving adhesion to the adherend rubber.

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.

From the viewpoint of improving adhesion to the adherend rubber, the content of the isocyanate compound (B) in the fiber treatment 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 modified conjugated diene rubber (A).
From the same viewpoint, the content of the isocyanate compound (B) in the fiber treatment 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 modified conjugated diene rubber (A).

<(C) Epoxy Compound Having Two or More Epoxy Groups in One Molecule>
The epoxy compound (C) 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 in one molecule.
From the viewpoint of improving adhesion to the adherend rubber, the number of epoxy groups that the epoxy compound (C) has in one molecule is 2 or more, preferably 3 or more, more preferably 4 or more, and is preferably 8 or less, more preferably 7 or less, and even more preferably 6 or less.
From the same viewpoint, the number of epoxy groups that the epoxy compound (C) has in one molecule is preferably 2 to 8, more preferably 3 to 7, and even more preferably 4 to 6.

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 rubber substrate, an aliphatic epoxy compound is preferred.
Examples of the aliphatic epoxy compound include difunctional aliphatic epoxy compounds and tri- or higher functional aliphatic epoxy compounds.
Examples of difunctional aliphatic epoxy compounds 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.

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, per 100 parts by mass of the modified conjugated diene rubber (A), 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.
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).

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

(D) Surfactants include, for example, cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. Of these, nonionic surfactants are preferred from the viewpoint of compatibility between the fiber treatment agent and the rubber substrate. These (D) surfactants may be used alone or in combination of two or more.

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, "Akatoru UA-90N,""AkatoruTN-100,""AkatoruPC-6,""AkatoruPC-8,""AkatoruPC-10," and "Akatoru SO-80," all manufactured by ADEKA Corporation.

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

Examples of anionic surfactants include carboxylates such as fatty acid soaps; sulfates such as higher alcohol sulfates, higher alkyl polyalkylene glycol ether sulfates, sulfates of styrenated phenol alkylene oxide adducts, sulfates of alkylphenol alkylene oxide adducts, sulfated oils, sulfated fatty acid esters, sulfated fatty acids, and sulfated olefins; sulfonates such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, naphthalene sulfonates, and formalin condensate salts of naphthalene sulfonic acid, α-olefin sulfonates, paraffin sulfonates, and sulfosuccinic acid diester salts; and higher alcohol phosphate salts.
If necessary, a nonionic surfactant and an anionic surfactant may be used in combination.

Examples of zwitterionic surfactants include alkylcarboxybetaines.

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 the (A) modified conjugated diene rubber is good, and a coated fiber having better adhesion to the coated rubber 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 of 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 between 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)
Nonionic surfactants can be identified by detecting and measuring the molecular weight and structural units using mass spectrometry, and by detecting and measuring the structure using ¹ H and ¹³ C-NMR, and the structure can be identified based on these, and the HLB value can be calculated using formula (I) based on the identified information. A method for separating nonionic surfactants from fiber treatment agents includes, for example, fractionation and isolation by reverse phase liquid chromatography.

From the viewpoint of improving the stability of the emulsion, the content of the surfactant (D) in the fiber treatment 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 treatment 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).

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

The oil (E) is not particularly limited as long as it is compatible with the modified conjugated diene rubber (A), and examples thereof include natural oils and synthetic oils.
Examples of natural oils include mineral oils and vegetable oils.
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. 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.

Examples of synthetic oils include hydrocarbon-based synthetic oils, ester-based synthetic oils, and ether-based 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-based 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 the ether-based synthetic oil include polyoxyalkylene glycol and polyphenyl ether.
Examples of commercially available synthetic oils include the "Linearene" series manufactured by Idemitsu Kosan Co., Ltd., and "FGC32,""FGC46," and "FGC68" manufactured by ANDEROL.

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 still 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 not more than 300 parts by mass, more preferably more than 0 parts by mass and not more than 200 parts by mass, even more preferably more than 0 parts by mass and not more than 100 parts by mass, and still more preferably more than 0 parts by mass and not more than 50 parts by mass, relative to 100 parts by mass of the (A) modified conjugated diene rubber.
The fiber treating agent may not contain the oil (E).

<Other ingredients>
The fiber treating agent of the present invention may contain components other than the above-mentioned components, as long as the components do not impair the adhesion to the rubber substrate.
Examples of the other components include (A) a polymer other than the modified conjugated diene rubber (for example, 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 treatment 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, relative to 100 parts by mass of the (A) modified conjugated diene rubber.

In the present invention, a coated fiber having excellent adhesiveness to the rubber coating can be obtained without containing formaldehyde, resins made from formaldehyde, resorcinol, or the like, which are harmful to the human body.
Examples of the resins made from formaldehyde 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 selected from the group consisting of formaldehyde and resins made from formaldehyde, 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, per 100 parts by mass of the modified conjugated diene rubber (A). It is particularly preferable that the fiber treatment agent is 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.

As described above, before the fiber treatment 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.
In the fiber treating agent of the present invention, the total amount of components other than the liquid medium 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, from the viewpoints of adhesiveness and ease of handling. When the total amount of components other than the liquid medium is within this 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.

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

When the fiber treating agent of the present invention is made into an emulsion, there is no particular limitation on the method for preparing the emulsion, and it can be prepared by a mechanical method or a chemical method.
Examples of mechanical methods include methods using a homogenizer, a homomixer, a disperser mixer, a colloid mill, a pipeline mixer, a high-pressure homogenizer, an ultrasonic emulsifier, etc., and these methods can be used alone or in combination.
Examples of chemical methods include 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.
In order to obtain an emulsion with a small particle size, it may be preferable to carry out the operation while heating the modified conjugated diene rubber (A) to an appropriate temperature (for example, 30 to 80°C) for the purpose of lowering the viscosity of the modified conjugated diene rubber.

In the present invention, for the purpose of increasing the stability of the emulsion, an alkaline substance such as sodium hydroxide, potassium hydroxide, or an amine may be added to adjust the pH before use, if necessary.
When an alkaline substance is added, the amount of alkaline substance added relative to 100 parts by mass of the (A) modified conjugated diene rubber in the emulsion is, from the viewpoint of improving the stability of the emulsion, 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, even more preferably 10 parts by mass or less.
From the same viewpoint, when an alkaline substance is added, the amount of the alkaline substance added relative to 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.

When producing the fiber treatment agent of the present invention, the order in which the components are mixed 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, and a (C) epoxy compound. When the fiber treatment agent of the present invention contains (E) oil, it is even 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, and a (C) epoxy compound. The (B) isocyanate compound and (C) epoxy compound may be mixed with other components while dissolved or dispersed in a liquid medium.

[Coated fiber and its manufacturing method]
The coated fiber of the present invention comprises a fiber and a coating that coats the surface of the fiber,
The coated material is a coated fiber, which contains at least one member selected from the group consisting of the fiber treating agent of the present invention and a reaction product of the fiber treating agent.
The "coated fiber" in the present invention may be a fiber in which at least a portion of the surface is coated with the coating, and may be a fiber in which the coating is present as, for example, a film, layer, or the like on at least a portion of the surface.

<Fiber>
The fibers contained in the coated fiber of the present invention are not particularly limited, and examples thereof include synthetic fibers, natural fibers, and regenerated fibers.

Synthetic fibers include, for example, polyamide fibers, polyvinyl alcohol fibers, polyester fibers, regenerated cellulose fibers, polyacrylamide fibers, polyolefin fibers, and wholly aromatic polyester fibers. 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.

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.

The fibers used in the coated fiber of the present invention may be short fibers or long fibers.
The fiber used in the coated fiber of the present invention may be in the form of a monofilament, a multifilament, or a spun yarn. Among these, a spun yarn is preferred from the viewpoints of processability and adhesion to the rubber coating. When a spun yarn is 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 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, or the like.
In the present invention, one type of fiber may be used alone, or two or more types may be used in combination.

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 raw material, from the viewpoint of improving adhesion to the rubber coating.

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 100% by mass or less, from the viewpoint of improving adhesion to the rubber coating and reinforcing strength.

The coated fiber of the present invention can be used in any form, 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.
An example of the use of the coated fiber of the present invention in the form of a woven fabric is tire bead tape, which is wrapped around multiple bead wires embedded in the bead portions 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 adhesiveness to the rubber coating, and is therefore suitable for use as a bead tape which requires durability.

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 adhesive strength of the coated fiber to rubber can be measured by the method described in the Examples.

<Method of manufacturing coated fiber>
Although there are no particular limitations on the method for producing the coated fiber of the present invention, a method in which the fiber treatment agent of the present invention is applied to a fiber and then heated to form a coating is preferred, because this method is preferred because the fiber treatment agent applied to the fiber reacts with the heat, and a coating containing a reaction product of the fiber treatment agent covers the fiber.
The reaction product of the fiber treatment agent is preferably 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 and fibers bonded together via a crosslinking agent.
When the reaction product of the fiber treatment agent contains (A) modified conjugated diene rubbers bonded to each other via a crosslinking agent, the reaction product contains a crosslinked product of appropriate molecular weight, improving process contamination resistance while maintaining adhesion to the adhered rubber. Furthermore, when the reaction product of the fiber treatment agent contains (A) modified conjugated diene rubber and fibers bonded 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 is preferably a method having 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, the surface of which has the fiber treatment agent attached.

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

<Step I-2: Step of Heat Treating the Fiber Obtained in Step I-1, Having a Fiber Treatment Agent Adhered to the 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 modified conjugated diene rubber (A) 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 less, more preferably 150 seconds or less, and even more preferably 120 seconds or less, and may be 0.1 seconds or more, 0.2 seconds or more, or 0.5 seconds or more.

[Molded body and its manufacturing method]
The molded article of the present invention is not particularly limited as long as it contains the coated fiber of the present invention. However, since the coated fiber of the present invention has excellent adhesion to the rubber coating, it is particularly preferable that the molded article be a molded article containing the coated fiber of the present invention and a rubber component (hereinafter also referred to as a "rubber molded article").
From the viewpoint of maintaining the shape of the rubber, the coated fiber used in the rubber molded article 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.

Examples of the rubber molded article include rubber products or components thereof, such as tires such as automobile tires, belts such as conveyor belts and timing belts, hoses such as automobile liquid fuel hoses, automobile 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 of automobile tires include various components such as belts, carcass plies, and breakers, which are made of composite materials of coated fibers and rubber components.
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.

The rubber molded article is preferably a molded article containing the coated fiber of the present invention and a rubber composition.
The rubber composition includes those containing a rubber component and compounding agents that are usually used in the rubber industry.
The rubber component is not particularly limited, but examples thereof 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 of two or more.
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 using natural rubber in combination with SBR, 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 of physical properties due to reversion of the rubber.

Examples of natural rubber include TSR (Technically Specified Rubber), such as SMR (Malaysian TSR), SIR (Indonesian TSR), and STR (Thai TSR), as well as 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.

As the SBR, any SBR generally used for tires can be used.
The styrene content of SBR is preferably from 0.1 to 70% by mass, more preferably from 5 to 50% by mass, and even more preferably from 15 to 35% by mass.
The vinyl content of the SBR is preferably from 0.1 to 60% by mass, more preferably from 0.1 to 55% by mass.
In the present invention, the term "styrene content" means the content of monomer units derived from styrene.

The weight average molecular weight (Mw) of 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 SBR is the polystyrene-equivalent weight average molecular weight (Mw) determined by gel permeation chromatography (GPC).
The SBR may be a modified SBR having a functional group introduced therein, as long as the effect of the present invention is not impaired. Examples of the functional group include an amino group, an alkoxysilyl group, a hydroxy group, an epoxy group, and a carboxy group.

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 any of spherical, fibrous and amorphous.

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

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

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.

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.
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, from the viewpoint of the mechanical properties of the crosslinked product.

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 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, xanthate compounds, etc. 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 usually 0.1 to 15 parts by mass, and preferably 0.1 to 10 parts by mass, per 100 parts by mass of the rubber component.

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.

When the rubber composition contains silica as a filler, it is preferable that the rubber composition further contains a silane coupling agent.
Examples of silane coupling agents include sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, chloro compounds, etc. 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, etc. are improved.

The rubber composition may contain, as needed, a softener such as a process oil, such as silicone oil, aromatic oil, TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), paraffin oil, or naphthenic oil; or a resin component, such as an aliphatic hydrocarbon resin, an alicyclic hydrocarbon resin, a C9 resin, a rosin resin, a coumarone-indene resin, or a phenolic resin, for the purpose of improving processability, flowability, or the like, 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.

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, provided the effects of the present invention are not impaired. Examples of antioxidants include hindered phenol compounds, phosphorus-based compounds, lactone compounds, and hydroxyl-based compounds. Examples of antioxidants include amine-ketone compounds, imidazole compounds, amine compounds, phenolic compounds, sulfur-based compounds, and phosphorus-based compounds. These additives may be used alone or in combination of two or more.

As a method for producing a rubber molded article, for example, by embedding the coated fiber of the present invention in an unvulcanized rubber composition and then vulcanizing the rubber composition, a molded article can be obtained in which the fiber and rubber component are bonded together via a coating containing one or more members selected from the group consisting of the fiber treatment agent of the present invention and reaction products of the fiber treatment agent.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.
[(A) Production of 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% by 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, it was confirmed that the polymer solution phase and the aqueous phase had separated, and then the water was separated. The polymer solution after washing was vacuum dried at 70°C for 24 hours to yield an 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)).

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

<Methods for 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 GPC (gel permeation chromatography) using the following measuring device and conditions:
・Apparatus: GPC device "GPC8020" manufactured by Tosoh Corporation
Separation column: "TSKgel G4000HXL" manufactured by Tosoh Corporation
・Detector: Tosoh Corporation "RI-8020"
Eluent: Tetrahydrofuran Eluent flow rate: 1.0 ml/min Sample concentration: 5 mg/10 ml
Column temperature: 40°C

<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.).

<Method for measuring glass transition temperature>
(A) 10 mg of the 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 differential of DSC, was taken as the glass transition temperature.

<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 polystyrene-equivalent number average molecular weight (Mn) using the following formula:
Average number of hydrogen-bonding functional groups per molecule = [(number average molecular weight (Mn)) / (molecular weight of styrene unit) × (average molecular weight of conjugated diene and other monomer units other than conjugated diene, if necessary)] / (equivalent weight of hydrogen-bonding functional group)
The method for calculating the equivalent weight of the hydrogen-bonding functional group can be appropriately selected depending on the type of the hydrogen-bonding functional group.

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 for 12 hours at 80° C. 3 g of the pretreated sample was dissolved in 180 mL of toluene and 20 mL of ethanol, and then neutralized with a 0.1 N ethanol solution of potassium hydroxide to determine the acid value using the following formula:
Acid value (mgKOH/g) = (AB) x F x 5.611/S
A: Amount of 0.1 N potassium hydroxide ethanol solution added for neutralization (mL)
B: Amount (mL) of 0.1 N potassium hydroxide ethanol solution added to a blank containing no sample
F: Titer of 0.1 N potassium hydroxide ethanol solution S: Mass of weighed sample (g)

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

<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 with stirring, to obtain an emulsion (E-1) in which oil droplets containing the modified conjugated diene rubber (A-1) were dispersed in water.

<Production of fiber treatment agent and coated fiber>
Examples 1 to 5 and Comparative Examples 1 to 2
The emulsion (E-1), a crosslinking agent, and water were mixed to obtain the composition shown in Table 2, thereby preparing a fiber treatment agent.
The details of the crosslinking agents listed 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), blocking agent 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 44% by mass). Dissociation temperature of blocking agent: 120°C or higher. (B'-4) Isocyanate compound as a comparative component: Blocking agent adduct of hexamethylene diisocyanate (trade name "SU268-A", manufactured by Meisei Chemical Industry Co., Ltd., solid content 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 fiber treatment agent obtained, and then the liquid was squeezed out with a roller.
The resulting fiber was then dried at 140°C for 60 seconds, further heat-treated at 200°C for 60 seconds, and then wound up to produce a coated fiber in which the fiber was coated with a coating containing one or more selected from the group consisting of a fiber treatment agent and a reaction product of the fiber treatment agent.
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

<Amount of coating attached>
Before the fiber treatment agent was applied, a sample of 100 m in length was taken and dried at 105° C. for 4 hours, after which the mass was measured and the measured value was taken as the mass before the coating treatment.
Next, the fiber treatment agent was applied by the method described in each example, and the fibers after drying and heat treatment were sampled at the same length. The samples were also dried at 105°C for 4 hours and then their masses were measured. The measured values were used as the masses after coating treatment.
The amount of coating attached to 100 parts by mass of fiber before applying the fiber treatment agent was calculated as [(mass after coating treatment) - (mass before coating treatment)] x 100/(mass before coating treatment).

<Rubber adhesive strength>
For the coated fibers prepared in each example, evaluation sheets were prepared by the following method, and the force (N/25.4 mm) required to peel the coated fibers from the rubber was measured using a T-type tester and evaluated as rubber adhesion. The results are shown in Table 2.
In the evaluation results of rubber adhesion, a larger value indicates a stronger adhesion between the coated fiber and the rubber. The evaluation sheets were prepared as follows.

Preparation of Evaluation Sheets: The coated fibers prepared in each example were arranged and fixed on masking tape in a blind-like pattern so that the fibers did not overlap. This was then overlapped with an unvulcanized rubber composition (hereinafter referred to as "NR/SBR unvulcanized rubber") primarily composed of NR/SBR rubber prepared according to the following formulation (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. The evaluation sheet was then prepared by press-vulcanizing the composition for 30 minutes at 150°C and a pressure of 20 kg/ ^cm² .

[NR/SBR unvulcanized rubber compounding composition]
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

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 makes it possible to obtain coated fibers with excellent adhesion to the rubber coating. Furthermore, when spun yarn is used, some of the fibers that make up the spun yarn deviate from the main axis of the yarn and are exposed on the surface of the fiber, thereby achieving even greater adhesive strength.

Comparative Example 3
A two-component fiber treatment agent was prepared without mixing the crosslinking agent and water with emulsion (E-1) to obtain the composition shown in Table 3. Specifically, the fibers shown in Table 3 were 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 fibers were then dried at 140°C for 60 seconds and further heat-treated at 200°C for 60 seconds. The resulting fibers were 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 fibers were wound up to produce coated fibers 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 fibers 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.

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 (15)

(A) a modified conjugated diene rubber;
(B) an isocyanate compound having a cyclic structure and having two or more groups selected from the group consisting of an isocyanate group and a blocked isocyanate group per molecule;
(C) an epoxy compound having two or more epoxy groups in one molecule;
A fiber treatment agent comprising: The fiber treatment agent according to claim 1, wherein the number average molecular weight (Mn) of the (A) modified conjugated diene rubber is 1,000 or more and 120,000 or less. The fiber treatment agent according to claim 1, 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. The fiber treatment agent according to claim 1, wherein the cyclic structure contained in component (B) is an aromatic ring. The present invention comprises a fiber and a coating that coats the surface of the fiber,
A coated fiber, wherein the coating comprises at least one selected from the group consisting of the fiber treating agent according to any one of claims 1 to 4 and a reaction product of the fiber treating agent. The coated fiber according to claim 5, 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 rubbers bonded to fibers via a crosslinking agent. 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. The coated fiber according to claim 5, wherein the amount of the coating attached is 5 to 15 parts by mass per 100 parts by mass of the fiber used as raw material. The coated fiber according to claim 5, wherein the fiber is a spun yarn. A molded article comprising the coated fiber described in claim 5. A method for producing the coated fiber of claim 5,
A method for producing a coated fiber, comprising: applying the fiber treating agent to the fiber and then heating the fiber to form the coating. 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. 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 material. The method for producing a coated fiber according to claim 11, wherein the fiber is a spun yarn. A method for producing a molded article using coated fibers produced by the coated fiber production method described in claim 11.