Coated fibers and molded body using same

Abstract

These coated fibers have excellent sizing performance and adhesion with rubber, as well as excellent strength after friction, and further, can be manufactured while suppressing contamination of manufacturing equipment. The coated fibers are characterized by being fibers coated with a coating containing one or more selected from the group consisting of an adhesive composition containing conjugated diene rubber and a reactant of the adhesive composition, and also characterized in that the molecular weight distribution curve by GPC analysis of the coating satisfies both condition (1) and condition (2). Condition (1): Has at least one peak with a molecular weight in the range from 2,600 to 19,000. Condition (2): The area ratio [(A) / (B)] is 0.5-9.0, where (A) is the area under the curve in in which the molecular weight is in the range from 2,600 to 19,000 and (B) is the area under the curve in which the molecular weight is in the range of 19,000-540,000.

Description

Coated fiber and molded article using the same

[0001] The present invention relates to a coated fiber having excellent adhesion to rubber, and a molded article using the same.

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

[0003] However, since formaldehyde is suspected of being carcinogenic and resorcinol is suspected of being an environmental hormone, the development of alternative materials is desired. Specifically, Patent Document 3 describes a reinforcing fiber having an adhesive component containing a conjugated diene rubber and an oil on at least a portion of the fiber surface, wherein the vapor pressure of the oil at 20°C is 10 Pa or less. Patent Document 4 also describes a surface-modified fiber having a fiber and a surface-modified layer covering at least a portion of the fiber surface, wherein the solid surface zeta potential of the surface of the surface-modified layer is within a specific range. Furthermore, Patent Document 5 describes a reinforcing fiber having a fiber, a surface-modified layer covering at least a portion of the fiber surface, and an adhesive layer containing a conjugated diene rubber covering at least a portion of the surface-modified layer, wherein the surface-modified layer contains a polyamine compound having one or more functional groups selected from primary to tertiary amino groups and imino groups and having a weight-average molecular weight (Mw) of 300 or more.

[0004] Japanese Patent Application Laid-Open No. 54-4976 Japanese Patent Application Laid-Open No. 58-2370 International Publication No. 2020 / 175404 International Publication No. 2021 / 106559 International Publication No. 2022 / 044460

[0005] In the reinforcing fibers described in Patent Documents 3 to 5, the adhesion between the fiber and the rubber is improved by adhering a liquid rubber with a relatively high molecular weight to the raw fiber. While such reinforcing fibers sufficiently adhere to the rubber, further improvement in adhesion was desired. Furthermore, when a liquid rubber with a relatively high molecular weight is applied to the fiber surface, the holding roller through which the fiber passes during the manufacturing process can be contaminated, resulting in reduced productivity. Therefore, there was a need for a bonding method that has excellent adhesive strength similar to conventional methods using RFL, does not deteriorate the fiber, and allows for efficient production with less contamination of manufacturing equipment.

[0006] An object of the present invention is to provide a coated fiber using an adhesive composition that does not contain resorcinol or formaldehyde, which has excellent adhesion to rubber, excellent convergence, and excellent strength after friction, and which can be produced while suppressing contamination of production equipment, and a molded article using the coated fiber.

[0007] As a result of intensive research by the present inventors to solve the above problems, they have found that even when a conjugated diene rubber having a relatively low molecular weight is used as the adhesive composition, by adjusting the molecular weight distribution curve of the coating by GPC analysis so that it has a peak in a specific range and further adjusting the two areas in the specific ranges by GPC analysis so that they have a specific ratio, it is possible to obtain a coated fiber that has excellent adhesion to rubber and convergence properties, and also has excellent strength after friction, without using resorcinol and formaldehyde, and it is also possible to suppress contamination of the production equipment, and they have completed the present invention based on this finding.

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

[12] . [1] A coated fiber obtained by coating a fiber with a coating material containing one or more selected from the group consisting of an adhesive composition containing a conjugated diene rubber and a reaction product of the adhesive composition, wherein the molecular weight distribution curve of the coating material as determined by GPC analysis satisfies both of the following conditions (1) and (2): <Condition (1)> The coating material has at least one peak in the molecular weight range of 2,600 to 19,000. <Condition (2)> When the area under the curve in the molecular weight range of 2,600 to 19,000 is (A) and the area under the curve in the molecular weight range of 19,000 to 540,000 is (B), the area ratio [(A) / (B)] is 0.5 to 9.0. [2] The coated fiber according to item [1] above, wherein the adhesive composition further contains a crosslinking agent. [3] The coated fiber according to [2] above, wherein the reaction product is one in which the conjugated diene rubbers are bonded together via a crosslinking agent, and / or the conjugated diene rubber and the fiber are bonded together via a crosslinking agent. [4] The coated fiber according to [2] or [3] above, wherein the crosslinking agent is at least one selected from the group consisting of epoxy resins and isocyanate resins. [5] The coated fiber according to any of [1] to [4] above, wherein the amount of the coating is 0.01 to 10.0 parts by mass per 100 parts by mass of the fiber. [6] The coated fiber according to any of [1] to [5] above, wherein the peak of the molecular weight distribution curve of the coating in GPC analysis is in the molecular weight range of 2,600 to 15,000. [7] The coated fiber according to any of [1] to [6] above, wherein the conjugated diene rubber is liquid. [8] The coated fiber according to any one of [1] to [7] above, wherein the conjugated diene rubber has a monomer unit derived from one or more selected from the group consisting of butadiene, isoprene, chloroprene, acrylonitrile, and farnesene. [9] The coated fiber according to any one of [1] to [8] above, wherein the adhesive composition further contains an oil having a vapor pressure of 10 Pa or less at 20°C.

[10] The coated fiber according to any one of [1] to [9] above, wherein the fiber is one or more selected from the group consisting of polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers.

[11] The coated fiber according to any one of [1] to

[10] above, obtained by applying an aqueous adhesive containing the conjugated diene rubber to the fiber and then heating it.

[12] A molded article using the coated fiber according to any one of [1] to

[11] above.

[0009] The present invention provides a coated fiber using an adhesive composition that does not contain resorcinol or formaldehyde, which has excellent adhesion and convergence to rubber, as well as excellent strength after friction, and can be produced while suppressing contamination of production equipment, and a molded article using the coated fiber.

[0010] Figure 1 is a schematic diagram showing a metal friction tester for coated fibers. Figure 2 is a reference diagram of a molecular weight distribution curve with a maximum point near a molecular weight of 7,000. Figure 3 is a reference diagram of a molecular weight distribution curve with a maximum point near a molecular weight of 10,000.

[0011] [Coated Fiber] The coated fiber of the present invention is a fiber coated with a coating containing one or more selected from the group consisting of an adhesive composition containing a conjugated diene rubber and a reaction product of the adhesive composition, and is characterized in that the molecular weight distribution curve of the coating determined by GPC analysis satisfies both of the following conditions (1) and (2): Note that the molecular weight distribution curve determined by GPC analysis in the present invention is one analyzed by the method described in the Examples.

[0012] <Condition (1)> In the present invention, the molecular weight distribution curve of the coating obtained by GPC analysis has at least one peak in the molecular weight range of 2,600 to 19,000. In this specification, "peak" refers to a maximum point in the molecular weight distribution curve. For example, in the molecular weight distribution curve shown in FIG. 2, a maximum point is observed near a molecular weight of approximately 7,000, which represents the peak. Similarly, in the molecular weight distribution curve shown in FIG. 3, a maximum point is observed near 10,000, which also represents the peak. In the present invention, "having at least one maximum point" refers to having at least one maximum point within a specific range. In a preferred embodiment of the present invention, the peak is derived from a component containing a conjugated diene rubber. Having at least one peak within this range can improve adhesion to rubber, particularly adhesion to low-polarity rubbers such as EPDM (ethylene propylene diene rubber), even when a low-molecular-weight conjugated diene rubber is used. Having a peak means that a component in a specific molecular weight range is present in greater amounts than other components, and adhesiveness can be achieved together with components having molecular weights in the vicinity of that range. Furthermore, by adjusting the molecular weight so that at least one peak is present within the above range, the coating does not contain compounds with excessively large molecular weights, making it possible to suppress process contamination during the production of the coated fiber. Having at least one peak within the above range can be achieved by using a low-molecular-weight conjugated diene rubber. Furthermore, it can also be achieved by crosslinking low-molecular-weight conjugated diene rubbers together using a crosslinking agent, as described below, to an extent that does not result in excessively high molecular weight. In the present invention, it is sufficient for the molecular weight to have at least one peak within the above range, but one peak is preferred, and the molecular weight range within which this peak exists is preferably 2,600 to 15,000, more preferably 4,500 to 14,000, even more preferably 6,000 to 13,000, even more preferably 7,000 to 12,000, and particularly preferably 8,000 to 11,000.

[0013] <Condition (2)> In the present invention, the molecular weight distribution curve of the coating obtained by GPC analysis, where (A) is the area under the curve in the molecular weight range of 2,600 to 19,000 and (B) is the area under the curve in the molecular weight range of 19,000 to 540,000, has an area ratio [(A) / (B)] of 0.5 to 9.0. When this area ratio is within this range, a good balance between relatively low molecular weight compounds and relatively high molecular weight compounds in the coating is achieved, thereby improving adhesion to the rubber and suppressing process contamination. Furthermore, the convergence of the coated fiber and its post-friction strength can also be improved. From these perspectives, the area ratio [(A) / (B)] is preferably 1.0 to 8.8, more preferably 1.4 to 8.7, and even more preferably 1.8 to 8.5. In a preferred embodiment of the present invention, the areas (A) and (B) are derived from components containing a conjugated diene rubber. From the viewpoint of a balance of the effects of the present invention, in a preferred embodiment, the area ratio [(A) / (B)] is preferably 1.0 to 5.0, more preferably 1.5 to 3.5, and even more preferably 2.0 to 3.5. The area ratio can be achieved, for example, by using low-molecular-weight conjugated diene rubbers and crosslinking the low-molecular-weight conjugated diene rubbers with each other using a crosslinking agent described below.

[0014] <Adhesive Composition> The adhesive composition used in the present invention contains a conjugated diene rubber. In a preferred embodiment of the present invention, the adhesive composition contains a modified conjugated diene rubber. In the present invention, a fiber is coated with a coating containing at least one selected from the group consisting of an adhesive composition containing a relatively low-molecular-weight conjugated diene rubber (preferably a modified conjugated diene rubber) and a reaction product of the adhesive composition (i.e., a reaction product obtained by reacting two conjugated diene rubbers (preferably a modified conjugated diene rubber)). The reaction product is obtained by adjusting the reaction product to prevent excessive reaction, thereby exhibiting excellent adhesive properties while not contaminating the manufacturing process. Furthermore, since the reaction product is composed of a compound with an appropriate molecular weight, the coated fiber of the present invention also has excellent convergence properties and strength after friction. Note that the "coated fiber" in the present invention may be any fiber in which at least a portion of the surface is coated with the coating. The coating may be present on at least a portion of the fiber surface, for example, as a film or layer. Alternatively, the coating may be contained in the raw material of the fiber and present on a portion of the surface of the fiber itself. The compounds used in the adhesive composition and the reaction products of the adhesive composition will be described in detail below.

[0015] [Conjugated Diene Rubber] The conjugated diene rubber used in the present invention contains at least a monomer unit derived from a conjugated diene (hereinafter also referred to as a "conjugated diene unit") in the molecule, and preferably contains 50 mol% or more of the monomer units derived from a conjugated diene based on all the monomer units in the conjugated diene rubber. Examples of the conjugated diene monomer include 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, acrylonitrile, and farnesene. These conjugated dienes may be used alone or in combination of two or more. From the viewpoint of reactivity during vulcanization, the conjugated diene rubber preferably has monomer units derived from one or more selected from the group consisting of butadiene, isoprene, chloroprene, acrylonitrile, and farnesene, and more preferably has monomer units derived from one or more selected from butadiene and isoprene.

[0016] The conjugated diene rubber used in the present invention may contain units derived from monomers other than the conjugated diene monomer, as long as the units do not impair adhesion. Examples of such other monomers include copolymerizable ethylenically unsaturated monomers and aromatic vinyl compounds. Examples of such ethylenically unsaturated monomers include olefins such as ethylene, 1-butene, and isobutylene. Examples of such 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 may be used alone or in combination of two or more. When the conjugated diene rubber contains a monomer unit derived from a monomer other than the conjugated diene monomer, the content thereof is preferably 30 mol % or less, more preferably 10 mol % or less, and further preferably 5 mol % or less.

[0017] The conjugated diene rubber used in the present invention may be unmodified, but preferably has a functional group in part thereof, preferably has a hydrogen-bonding functional group, and more preferably is a modified conjugated diene rubber containing conjugated diene units in at least a portion of the polymer chain and having a hydrogen-bonding functional group in a side chain or terminal of the polymer chain. Unmodified conjugated diene rubber and modified conjugated diene rubber may be used in combination. The modified conjugated diene rubber interacts with the adherend rubber and fiber, respectively, leading to more effective adhesion between the two. When the modified conjugated diene rubber and the adherend rubber are vulcanized to form a covalent bond, a strong cohesive force is generated, further improving adhesion. Furthermore, when hydrophilic fibers are used as the fibers, it is believed that the hydrogen-bonding functional groups contained in the modified conjugated diene rubber form hydrogen bonds with the hydrophilic fibers, thereby improving adhesion.

[0018] In this specification, the term "hydrogen bond" refers to a bonding interaction formed between a hydrogen atom (donor) that is bonded to an atom with high electronegativity (such as O, N, or S) and is electrically positively polarized, and an electronegative atom (acceptor) that has a lone pair of electrons.

[0019] In the present invention, a "hydrogen-bonding functional group" refers to a functional group that can function as a donor and acceptor in the 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. Derivatives of aldehyde groups include acetalized derivatives thereof. Derivatives of carboxy groups include salts thereof, esterified derivatives thereof, amidated derivatives thereof, and acid anhydrides thereof. Derivatives of silanol groups include esterified derivatives thereof. Furthermore, examples of carboxy groups include groups derived from monocarboxylic acids and groups derived from dicarboxylic acids. Among these, one or more selected from a hydroxy group, an aldehyde group, an acetalized product of an aldehyde 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 carbonyl group, a silanol group, an esterified product of a silanol group, an amino group, an imidazole group, and a mercapto group are preferred.

[0020] Among these, from the viewpoint of improving adhesion and ease of production of the modified conjugated diene rubber, one or more selected from 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 preferred, one or more selected from a carboxy group, an esterified product of a carboxy group, and an acid anhydride of a carboxy group are more preferred, and an esterified product of maleic anhydride and a functional group derived from maleic anhydride are even more preferred.

[0021] From the viewpoint of obtaining a coated fiber having excellent rubber adhesion, the number of hydrogen-bonding functional groups in the 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 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.

[0022] The average number of hydrogen-bonding functional groups per molecule of the modified conjugated diene rubber is calculated from the equivalent weight (g / eq) of the hydrogen-bonding functional groups of the modified conjugated diene rubber and the number average molecular weight Mn in terms of styrene, according to the following formula: The equivalent weight of the hydrogen-bonding functional groups of the modified conjugated diene rubber means the mass of the conjugated diene and other monomers other than the conjugated diene, which are included as needed, bonded to each hydrogen-bonding functional group: Average number of hydrogen-bonding functional groups per molecule = [(number average molecular weight (Mn)) / (molecular weight of styrene unit) x (average molecular weight of conjugated diene and other monomer units other than the conjugated diene, which are included as needed)] / (equivalent weight of hydrogen-bonding functional group) The method for calculating the equivalent weight of the hydrogen-bonding functional group can be selected appropriately depending on the type of hydrogen-bonding functional group.

[0023] Examples of methods for obtaining a modified conjugated diene rubber include a method of adding a modifying compound to a polymer of a conjugated diene monomer (hereinafter also referred to as "production method (1)"), a method of oxidizing a conjugated diene polymer (hereinafter also referred to as "production method (2)"), a method of copolymerizing a conjugated diene monomer with a radically polymerizable compound having a hydrogen-bonding functional group (hereinafter also referred to as "production method (3)"), and a method of adding a modifying compound capable of reacting with an active polymerization terminal to a polymer of an unmodified conjugated diene monomer having an active polymerization terminal before adding a polymerization terminator (hereinafter also referred to as "production method (4)").

[0024] - Manufacturing method (1) of modified conjugated diene rubber Manufacturing method (1) is a method of adding a modifying compound to a polymer of a conjugated diene monomer, i.e., an unmodified conjugated diene rubber (hereinafter also referred to as "unmodified conjugated diene rubber"). The unmodified conjugated diene rubber can be obtained by polymerizing a conjugated diene and, if necessary, other monomers other than the conjugated diene, for example, by emulsion polymerization or solution polymerization. Of the above methods, solution polymerization is preferred as a method of manufacturing the unmodified conjugated diene rubber.

[0025] The solution polymerization method may be a known method or a method similar to a known method. For example, a predetermined amount of a monomer containing a conjugated diene is polymerized in a solvent using a Ziegler catalyst, a metallocene catalyst, or an anionically polymerizable active metal or active metal compound, optionally in the presence of a polar compound. Examples of the solvent 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.

[0026] Examples of anionically polymerizable active metals include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among these anionically polymerizable active metals, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred.

[0027] The anionically polymerizable active metal compound is preferably an organic alkali metal compound. Examples of the organic alkali metal compound include organic monolithium compounds such as methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; polyfunctional organic lithium compounds such as dilithiomethane, dilithionaphthalene, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene, and the like. Among these organic alkali metal compounds, organic lithium compounds are preferred, and organic monolithium compounds are more preferred.

[0028] 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 modified conjugated diene rubber, but is usually used in an amount of 0.01 to 3 parts by mass per 100 parts by mass of all monomers including conjugated diene. The organic alkali metal compound can also be used as an organic alkali metal amide by reacting it with a secondary amine such as dibutylamine, dihexylamine, or dibenzylamine.

[0029] In anionic polymerization, polar compounds are typically 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 typically used in an amount of 0.01 to 1,000 moles per mole of the organic alkali metal compound. The solution polymerization temperature is typically −80 to +150°C, preferably 0 to 100°C, and more preferably 10 to 90°C. The polymerization can be carried out batchwise or continuously. The polymerization reaction can be terminated by adding a polymerization terminator. Examples of the polymerization terminator include alcohols such as methanol and isopropanol. The unmodified conjugated diene rubber can be isolated by pouring the resulting polymerization reaction solution into a poor solvent such as methanol to precipitate the polymer, or by washing the polymerization reaction solution with water, separating it, and then drying it.

[0030] The emulsion polymerization method may be a known method or a method similar to a known method. For example, a predetermined amount of a monomer containing a conjugated diene is emulsified and dispersed in the presence of an emulsifier, followed by emulsion polymerization using a radical polymerization initiator. Examples of the emulsifier include long-chain fatty acid salts having 10 or more carbon atoms and rosin acid salts. Examples of long-chain fatty acid salts include potassium salts or sodium salts of fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid. Water is typically used as the dispersion solvent, and 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.

[0031] The temperature of the emulsion polymerization can be appropriately set depending on the type of radical polymerization initiator used, etc., but is usually 0 to 100° C., preferably 0 to 60° C. The polymerization method may be either continuous polymerization or batch polymerization.

[0032] The polymerization reaction can be terminated by adding a polymerization terminator, such as an amine compound such as isopropylhydroxylamine, diethylhydroxylamine, or hydroxylamine, a quinone compound such as hydroquinone or benzoquinone, or sodium nitrite.

[0033] After the polymerization reaction is terminated, an antioxidant may be added as needed. After the polymerization reaction is terminated, unreacted monomers are removed from the obtained latex as needed. Next, the polymer is coagulated using a salt such as sodium chloride, calcium chloride, or potassium chloride as a coagulant, and an acid such as nitric acid or sulfuric acid is added as needed 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 and an extender oil previously prepared as an emulsified dispersion may be mixed as needed, and the oil-extended unmodified conjugated diene rubber may be recovered.

[0034] (Modifying compound used in production method (1)) There are no particular restrictions on the modifying compound used in production method (1), but from the viewpoint of improving the adhesiveness of the coated fiber, one having a hydrogen-bonding functional group is preferred. Examples of the hydrogen-bonding functional group include those similar to those described above. Among them, from the viewpoint of the strength of the hydrogen bonding force, an amino group, an imidazole group, a urea group, a hydroxy group, a mercapto group, a silanol group, an aldehyde group, a carboxy group, and derivatives thereof are preferred. As a derivative of a carboxy group, a salt thereof, an esterified product thereof, an amidated product thereof, or an acid anhydride thereof is preferred. These modifying compounds having a hydrogen-bonding functional group may be used alone or in combination of two or more types.

[0035] Examples of the modifying compound include unsaturated carboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid; unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, and itaconic anhydride; unsaturated carboxylic esters such as maleic esters, fumaric esters, citraconic esters, and itaconic esters; unsaturated carboxylic amides such as maleic amides, fumaric amides, citraconic amides, and itaconic amides; unsaturated carboxylic imides such as maleic imide, fumaric imide, citraconic imide, and itaconic imide; vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, mercaptomethyl methyl diene mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethylmethoxydimethylsilane, 2-mercaptoethylethoxydimethylsilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyldiethoxymethylsilane, 3-mercaptopropyldimethoxyethylsilane, 3-mercaptopropyldiethoxyethylsilane, 3-mercaptopropylmethoxydimethylsilane, and 3-mercaptopropylethoxydimethylsilane.

[0036] The amount of the modifying compound used is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 50 parts by mass, and even more preferably 1 to 30 parts by mass, per 100 parts by mass of the unmodified conjugated diene rubber.

[0037] The reaction temperature is usually preferably 0 to 200°C, more preferably 50 to 200°C.

[0038] The amount of the modifying compound added to the 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 to the 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.

[0039] 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 is heated with one or more modifying compounds selected from unsaturated carboxylic acids, unsaturated carboxylic acid derivatives, and silane compounds, and optionally a radical generator, in the presence or absence of an organic solvent. The radical generator used is not particularly limited, and commercially available organic peroxides, azo compounds, hydrogen peroxide, and the like can be used. Organic solvents used in the method generally include hydrocarbon solvents and halogenated hydrocarbon solvents. Among these organic solvents, hydrocarbon solvents such as n-butane, n-hexane, n-heptane, cyclohexane, benzene, toluene, and xylene are preferred.

[0040] Alternatively, the modifying compound may be grafted onto an unmodified conjugated diene rubber to introduce a hydrogen-bonding functional group, and then a modifying compound capable of reacting with the functional group may be added to introduce another hydrogen-bonding functional group into the polymer. Specific examples of such methods include grafting maleic anhydride onto an unmodified conjugated diene rubber obtained by living anionic polymerization, followed by reaction with a compound having a hydroxyl group, such as 2-hydroxyethyl methacrylate or methanol, or a compound such as water.

[0041] Furthermore, when carrying out a reaction to add a modifying compound to an unmodified conjugated diene rubber or a modified conjugated diene rubber (a conjugated diene rubber having a hydrogen-bonding functional group introduced therein, obtained by the above-mentioned method), an antioxidant may be added from the viewpoint of suppressing side reactions. Such antioxidants can be commercially available, and examples thereof include butylated hydroxytoluene (BHT) and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (Nocrac 6C). The amount of antioxidant added is preferably 0.01 to 10 parts by mass, and 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 can be obtained in good yield.

[0042] - Manufacturing Method (2) of Modified Conjugated Diene Rubber Examples of the manufacturing method (2) include a method of oxidizing a raw material unmodified conjugated diene rubber to obtain an oxidized conjugated diene rubber having functional groups or bonds containing oxygen generated in the molecule by an oxidation reaction. Specific examples of such functional groups or bonds include hydroxyl groups, aldehyde groups, carbonyl groups, carboxyl groups, and ether bonds. The unmodified conjugated diene rubber can be obtained by a method similar to the manufacturing method (1). Examples of methods for oxidizing the raw material conjugated diene rubber include a method of heat treating the raw material conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (hereinafter also referred to as "manufacturing method (2-1)") and a method of activating the raw material conjugated diene rubber by irradiating it with light having an absorption wavelength of the raw material conjugated diene rubber to cause it to react with oxygen (hereinafter also referred to as "manufacturing method (2-2)"). Among these, the method of heat treating the raw material conjugated diene rubber at a temperature equal to or higher than the oxidation temperature (manufacturing method (2-1)) is preferred. The stage at which the oxidation reaction of the conjugated diene rubber is carried out is not particularly limited, and may be carried out before mixing the conjugated diene rubber with oil, after mixing the conjugated diene rubber with oil, or after adhering the mixed conjugated diene rubber and oil to the fibers.

[0043]

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

[0034] Production method (2-1) is a method in which a raw material unmodified conjugated diene rubber is heat-treated at a temperature equal to or higher than the oxidation temperature. The heat treatment is carried out in an oxygen-containing atmosphere, preferably an air atmosphere. The heat treatment temperature is not particularly limited as long as it is a temperature at which the raw material conjugated diene rubber is oxidized. However, from the viewpoint of increasing the oxidation reaction rate and improving productivity, it is preferably 150°C or higher, more preferably 170°C or higher, and even more preferably 190°C or higher. When the raw material conjugated diene rubber is oxidized on the surface of hydrophilic fibers as described below, it is preferably 240°C or lower, more preferably 220°C or lower, from the viewpoint of preventing fiber deterioration. The heat treatment time is not particularly limited as long as it is within a range in which the raw material conjugated diene rubber is not deteriorated, but is preferably 30 minutes or shorter, more preferably 20 minutes or shorter. From the viewpoint of sufficiently oxidizing the unmodified conjugated diene rubber, the heat treatment time is preferably 1 second or longer, more preferably 10 seconds or longer, and even more preferably 30 seconds or longer. Furthermore, the temperature required for the oxidation reaction can be lowered by adding a thermal radical generator to the raw material conjugated diene rubber.

[0044] Examples of the thermal radical generator include peroxides, azo compounds, and redox initiators. Among these, peroxides are preferred from the viewpoint that the thermal radical generator bonds with the conjugated diene rubber and an oxygen-containing structure is added to the conjugated diene rubber. Examples of the peroxides include t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctanoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutyrate, lauroyl peroxide, t-amyl peroxypivalate, t-butyl peroxypivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate, and ammonium persulfate.

[0045] Examples of the azo compound include azobisisobutyronitrile (AIBN), 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-butanenitrile), 4,4'-azobis(4-pentanoic acid), 1,1'-azobis(cyclohexanecarbonitrile), 2-(t-butylazo)-2-cyanopropane, and 2,2'-azobis[2-methyl-N-(1,1)-bis(hydroxymethyl)-2-hydroxyethyl]propane. Examples of the thermal radical generators include 2,2'-azobis(2-methyl-N-hydroxyethyl)propionamide, 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dichloride, 2,2'-azobis(N,N-dimethyleneisobutylamide), 2,2'-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide), 2,2'-azobis(isobutylamide) dihydrate, etc. The thermal radical generators can be used alone or in combination of two or more.

[0046] Alternatively, a redox initiator may be used as the thermal radical generator, such as a combination of persulfate, acidic sodium sulfite, and ferrous sulfate, a combination of t-butyl hydroperoxide, acidic sodium sulfite, and ferrous sulfate, or a combination of p-menthane hydroperoxide, ferrous sulfate, sodium ethylenediaminetetraacetate, and sodium formaldehyde sulfoxylate.

[0047]

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

[0034] Production method (2-2) is a method in which the raw material unmodified conjugated diene rubber is activated by irradiating it with light of an absorption wavelength thereof, thereby causing it to react with oxygen. Production method (2-2) is carried out in an oxygen-containing atmosphere, preferably an air atmosphere. There are no particular restrictions on the wavelength of the light used, as long as it is a wavelength that is absorbed by the raw material conjugated diene rubber to cause a radical reaction, but ultraviolet light, which is strongly absorbed by the raw material conjugated diene rubber, is preferred. In addition, the amount of light irradiation required for the oxidation reaction can be reduced by adding a photoradical generator to the raw material conjugated diene rubber.

[0048] Examples of the photoradical generator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4,4′-dimethoxybenzophenone, benzoin propyl ether, benzil dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-hydroxy- Examples of such photoradical generators include bis-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, etc. The photoradical generators can be used alone or in combination of two or more.

[0049] - Manufacturing Method (3) of Modified Conjugated Diene Rubber Examples of the manufacturing method (3) include a method in which a conjugated diene monomer and a radically polymerizable compound having a hydrogen-bonding functional group are randomly copolymerized, block copolymerized, or graft copolymerized by a known method.

[0050] (Radically polymerizable compound having a hydrogen-bonding functional group used in production method (3)) The radically 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. Specific examples include aldehydes having a reactive multiple bond, acetalized products of the aldehydes; monocarboxylic acids having a reactive multiple bond, salts of the monocarboxylic acids, esterified products of the monocarboxylic acids, acid anhydrides of the monocarboxylic acids; dicarboxylic acids having a reactive multiple bond, salts of the dicarboxylic acids, esterified products of the dicarboxylic acids, acid anhydrides of the dicarboxylic acids; and amine compounds having a reactive multiple bond.

[0051] Among the aldehydes having a 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, and 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, el Alkenals having 3 to 30 carbon atoms, preferably alkenals having 3 to 25 carbon atoms, such as cinnamaldehyde, 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, Examples of unsaturated aldehydes include alkatrienals having 7 to 30 carbon atoms, such as aldehyde, preferably alkatrienals having 7 to 25 carbon atoms; alkatetraenals having 9 to 30 carbon atoms, such as stearidone aldehyde and arachidone aldehyde, preferably alkatetraenals having 9 to 25 carbon atoms; and alkapentaenals having 11 to 30 carbon atoms, such as eicosapentaene aldehyde, preferably alkapentaenals having 11 to 25 carbon atoms. Note that, when the aldehydes have cis-trans isomers, they include both the cis and trans isomers. These aldehydes may be used alone or in combination of two or more.

[0052] Among the acetalized products of aldehydes having a multiple bond, examples of the acetalized product of an aldehyde having a reactive carbon-carbon double bond include acetalized products of the aldehydes, specifically 3-(1,3-dioxalan-2-yl)-3-methyl-1-propene, which is an acetalized product of 2-methyl-3-butenal, and 3-(1,3-dioxalan-2-yl)-2-methyl-1-propene, which is an acetalized product of 3-methyl-3-butenal.

[0053] Among the aldehydes having a multiple bond and acetalized products of the aldehydes, examples of the aldehydes having a reactive carbon-carbon triple bond and acetalized products thereof include aldehydes having a carbon-carbon triple bond such as propioaldehyde, 2-butyn-1-al, and 2-pentyn-1-al, and acetalized products of the aldehydes.

[0054] Among the aldehydes having a multiple bond and the acetalized products of the aldehydes, aldehydes having a reactive carbon-carbon double bond are preferred, such as 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, Among them, one or more selected from acrolein, methacrolein, crotonaldehyde, and 3-butenal are more preferred because of their good reactivity during copolymerization.

[0055] Examples of the monocarboxylic acid having a multiple bond, the salt of the monocarboxylic acid, the ester of the monocarboxylic acid, and the acid anhydride of the monocarboxylic acid include (meth)acrylic acid, the sodium salt of (meth)acrylic acid, the potassium salt of (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxyl (meth)acrylate. Butyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, vinyl (meth)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, 3- Methyl methyl-3-butenoate, vinyl 3-methyl-3-butenoate, methyl 4-pentenoate, vinyl 4-pentenoate, methyl 2-methyl-4-pentenoate, vinyl 2-methyl-4-pentenoate, methyl 5-hexenoate, vinyl 5-hexenoate, methyl 3,3-dimethyl-4-pentenoate, vinyl 3,3-dimethyl-4-pentenoate, methyl 7-octenoate, vinyl 7-octenoate, methyl trans-3-pentenoate, vinyl trans-3-pentenoate, methyl trans-4-decenoate, vinyl trans-4-decenoate, 3-methyl-3-butenoate Ethenoate, ethyl 4-pentenoate, ethyl 2-methyl-4-pentenoate, ethyl 5-hexenoate, ethyl 3,3-dimethyl-4-pentenoate, ethyl 7-octenoate, ethyl trans-3-pentenoate, ethyl trans-4-decenoate, methyl 10-undecenoate, vinyl 10-undecenoate, (meth)acrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, cinnamic anhydride, crotonic anhydride, 3-methyl-3-butenoic anhydride, 4-pentenoic anhydride, 2-methyl-4-pentenoic anhydride, 5-hexenoic anhydride, 3,Examples of the carboxylic acid include carboxylic acids having a reactive carbon-carbon double bond, such as 3-dimethyl-4-pentenoic anhydride, 7-octenoic anhydride, trans-3-pentenoic anhydride, trans-4-decenoic anhydride, and 10-undecenoic anhydride, salts of the carboxylic acid, esterified products of the carboxylic acid, and anhydrides of the carboxylic acid; 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, tetrol acid, methyl tetrolate, ethyl tetrolate, and vinyl tetrolate. In this specification, the term "(meth)acrylic acid" collectively refers to "acrylic acid" and "methacrylic acid."

[0056] Examples of the dicarboxylic acid having a multiple bond, the salt of the dicarboxylic acid, the esterified product of the dicarboxylic acid, and the acid anhydride of the dicarboxylic acid include dicarboxylic acids having a reactive carbon-carbon double bond, salts of the dicarboxylic acid, esterified products of the dicarboxylic acid, and acid anhydrides of the dicarboxylic acid, such as maleic acid, sodium maleate, potassium maleate, methyl maleate, dimethyl maleate, maleic anhydride, itaconic acid, methyl itaconate, dimethyl itaconate, itaconic anhydride, himic acid, methyl himic acid, dimethyl himic acid, and himic acid anhydride.

[0057] As the monocarboxylic acid having a multiple bond, the salt of the monocarboxylic acid, the esterified product of the monocarboxylic acid, the monocarboxylic acid anhydride, the dicarboxylic acid having a multiple bond, the salt of the dicarboxylic acid, the esterified product of the dicarboxylic acid, and the acid anhydride of the dicarboxylic acid, a compound having a reactive carbon-carbon double bond is preferred, and among these, one or more selected from methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, vinyl (meth)acrylate, (meth)acrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, cinnamic anhydride, crotonic anhydride, methyl maleate, dimethyl maleate, maleic anhydride, methyl itaconate, dimethyl itaconate, and itaconic anhydride are more preferred because of their good reactivity during copolymerization.

[0058] Among the amine compounds having a 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, etc. Among these, one or more selected from allylamine, 3-butenylamine, and 4-pentenylamine are preferred because of their good reactivity during copolymerization.

[0059] - Manufacturing Method (4) of Modified Conjugated Diene Rubber Manufacturing method (4) is a method in which a modifying compound capable of reacting with an active polymerization end is added to a polymer of an unmodified conjugated diene monomer having an active polymerization end (unmodified conjugated diene rubber) before adding a polymerization terminator. The unmodified conjugated diene rubber having an active polymerization end can be obtained by polymerizing a conjugated diene monomer and, if necessary, a monomer other than the conjugated diene, for example, by emulsion polymerization or solution polymerization, as in the manufacturing method (1). Examples of the modifying compound that can be used in production method (4) include modifiers 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, as well as other modifiers described in JP 2011-132298 A.

[0060] In the production method (4), for example, when polymerization is performed using an organic alkali metal compound, the amount of the modifying compound used is preferably 0.01 to 100 molar equivalents relative to the organic alkali metal compound. The reaction temperature is usually −80 to +150° C., preferably 0 to 100° C., and more preferably 10 to 90° C. Alternatively, the modifying compound may be added before the addition of the polymerization terminator to introduce a hydrogen-bonding functional group into the unmodified conjugated diene rubber, and then a modifying compound reactive with the functional group may be further added to introduce another hydrogen-bonding functional group into the polymer.

[0061] The modified conjugated diene rubber may contain units derived from other monomers than the conjugated diene monomer and the radically polymerizable compound having a hydrogen-bonding functional group, as long as the amount does not impair adhesion. Examples of other monomers include copolymerizable ethylenically unsaturated monomers and aromatic vinyl compounds, and the specific compounds and their contents are the same as those described above.

[0062] There are no particular limitations on the method for producing the modified conjugated diene rubber, but from the viewpoint of productivity, it is preferable to produce it by production method (1), (2) or (3), more preferably by production method (1) or (3), and even more preferably by production method (1).

[0063] (Physical Properties of Conjugated Diene Rubber) The weight average molecular weight (Mw) of the conjugated diene rubber is not particularly limited, but it is preferable to include at least a low molecular weight conjugated diene rubber in the following range. Specifically, from the viewpoint of improving adhesiveness, the weight average molecular weight of the low molecular weight conjugated diene rubber 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 even be 7,000 or more, and from the viewpoint of handleability, it is preferably 26,000 or less, more preferably 20,000 or less, even more preferably 15,000 or less, still more preferably 12,000 or less, and even more preferably 10,000 or less. More specifically, the weight average molecular weight is preferably 1,000 to 26,000, more preferably 2,000 to 20,000, even more preferably 3,000 to 15,000, even more preferably 4,000 to 12,000, even more preferably 5,000 to 10,000, and even more preferably 7,000 to 10,000. A preferred embodiment of the coating in the coated fiber of the present invention is one that contains two or more different conjugated diene rubbers. Here, "different types of conjugated diene rubbers" means that at least one of the physical properties or characteristics, such as the type of monomer unit contained, the presence or absence of functional groups (modification or non-modification), the type and number of functional groups, weight average molecular weight, and number average molecular weight, is different.

[0064] The number average molecular weight (Mn) of the conjugated diene rubber is not particularly limited, but from the viewpoint of improving adhesion, it is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 2,500 or more, even more preferably 3,000 or more, and even more preferably 3,500 or more, and from the viewpoint of handleability, it is preferably 20,000 or less, more preferably 18,000 or less, and even more preferably 15,000 or less. More specifically, the number average molecular weight is preferably 1,000 to 20,000, more preferably 2,000 to 18,000, even more preferably 2,500 to 15,000, even more preferably 3,000 to 15,000, and even more preferably 3,500 to 15,000. The Mw and Mn of the conjugated diene rubber are the weight average molecular weight and number average molecular weight in terms of polystyrene obtained by measurement using gel permeation chromatography (GPC), and can be determined specifically by the method described in the Examples. The weight average molecular weight and number average molecular weight of the conjugated diene rubber can be adjusted to the desired values ​​by adjusting the type and amount of solvent in the production method.

[0065] The molecular weight distribution (Mw / Mn) of the conjugated diene rubber is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, even more preferably 1.0 to 2.0, even more preferably 1.0 to 1.5, and particularly preferably 1.0 to 1.3. When Mw / Mn is within the above range, the viscosity of the 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 standard polystyrene, determined by GPC measurement.

[0066] Furthermore, from the viewpoint of adhesiveness between the conjugated diene rubber and the fiber, the conjugated diene rubber is preferably liquid. In this specification, "liquid" means that the melt viscosity of the conjugated diene rubber measured at 38°C is 4,000 Pa·s or less. From the viewpoint of improving adhesiveness, the melt viscosity 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. From the viewpoint of handleability, the melt viscosity 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. More specifically, the melt viscosity measured at 38°C is preferably 0.1 to 4,000 Pa·s, more preferably 0.1 to 2,000 Pa·s, even more preferably 0.5 to 1,500 Pa·s, and even more preferably 1.0 to 1,000 Pa·s. When the melt viscosity is within the above range, the adhesiveness of the conjugated diene rubber can be improved while improving the handleability. The melt viscosity of the conjugated diene rubber means the viscosity measured at 38°C using a Brookfield viscometer (B-type viscometer), and specifically can be determined by the method described in the examples.

[0067] The glass transition temperature (Tg) of the conjugated diene rubber may vary depending on the vinyl content of the conjugated diene units, the type of conjugated diene, the content of 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 Tg is in the above range, an increase in viscosity can be suppressed, making the rubber easier to handle. The Tg can be determined by the method described in the examples.

[0068] The vinyl content of the conjugated diene rubber is preferably 80 mol% or less, more preferably 50 mol% or less, and even more preferably 30 mol% or less. The lower limit of the vinyl content may be 0 mol%, and the vinyl content may be 0 mol%. When the vinyl content is within the above range, the adhesiveness is improved. In this specification, "vinyl content" means the total mol% of conjugated diene units bonded by 1,2-bonds or 3,4-bonds (conjugated diene units bonded by bonds other than 1,4-bonds) out of a total of 100 mol% of conjugated diene units contained in the conjugated diene rubber. The vinyl content is 1 Using H-NMR, it can be calculated from the ratio of the integral values ​​of the signal derived from the conjugated diene units bonded via 1,2- or 3,4-bonds to the signal derived from the conjugated diene units bonded via 1,4-bonds.

[0069] From the viewpoint of improving adhesion to rubber, the content of the conjugated diene rubber in the aqueous adhesive described below is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 25% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less. More specifically, the content of the conjugated diene rubber in the aqueous adhesive described below is preferably 0.1 to 25% by mass, more preferably 0.5 to 15% by mass, even more preferably 1 to 10% by mass, and even more preferably 1 to 5% by mass. When the content of the conjugated diene rubber in the aqueous adhesive is within the above range, sufficient adhesive strength can be obtained while preventing the viscosity of the aqueous adhesive from becoming extremely high.

[0070] [Crosslinking Agent] In the present invention, the adhesive composition preferably contains a crosslinking agent. By using a crosslinking agent, even when a low-molecular-weight conjugated diene rubber is used, the low-molecular-weight conjugated diene rubbers can be bonded together via covalent bonds, and the conjugated diene rubber can be bonded to the fiber via covalent bonds. Furthermore, by using a crosslinking agent, the conjugated diene rubber is less likely to be absorbed by the rubber to be adhered (adherend), even when temperatures reach high levels during vulcanization, thereby enabling sufficient adhesive strength to be exhibited. In particular, the use of a crosslinking agent in the present invention results in excellent adhesion to adherends made of highly polar rubber. Furthermore, the use of a crosslinking agent in the present invention can improve the convergence of the coated fiber and also improve its strength after friction.

[0071] The crosslinking agent used in the present invention is not particularly limited as long as it is a compound capable of forming a covalent bond with both the conjugated diene rubber and the fiber, and examples thereof include epoxy resins, isocyanate resins, oxazoline group-containing resins, carbodiimide group-containing resins, amino resins, and polyester resins. Among these, one or more selected from the group consisting of epoxy resins and isocyanate resins are preferred, and it is more preferred to use an epoxy resin and an isocyanate resin in combination.

[0072] From the viewpoint of suppressing absorption of the conjugated diene rubber into the rubber adherend and improving adhesive strength, the content of the crosslinking agent in the aqueous adhesive described below is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. More specifically, the content of the crosslinking agent in the aqueous adhesive described below is preferably 0.01 to 15% by mass, more preferably 0.5 to 10% by mass, and even more preferably 0.8 to 5% by mass. When the content of the crosslinking agent in the aqueous adhesive is equal to or greater than the lower limit, the crosslinking agent reacts with the conjugated diene rubber, suppressing absorption of the conjugated diene rubber into the elastomer. This also improves the convergence of the coated fiber and the strength after friction. On the other hand, when the content of the crosslinking agent in the aqueous adhesive is equal to or less than the upper limit, the adhesive strength of the adhesive composition can be prevented from becoming excessively high.

[0073] Furthermore, in the aqueous adhesive described below, the content of the crosslinking agent per 100 parts by mass of the conjugated diene rubber is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 45 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 80 parts by mass or less, from the viewpoint of improving adhesion to the rubber. More specifically, in the aqueous adhesive described below, the content of the crosslinking agent per 100 parts by mass of the conjugated diene rubber is preferably 10 to 100 parts by mass, more preferably 30 to 90 parts by mass, and even more preferably 45 to 80 parts by mass.

[0074] [Oil] In the present invention, it is preferable that the adhesive composition further contains an oil having a vapor pressure of 10 Pa or less at 20°C. When the adhesive composition contains the oil, the oil does not volatilize for a long period of time even after the adhesive composition is applied to the surface of a fiber, making it less likely that the adhesive composition will become unevenly coated. This improves the adhesion of the adhesive composition and also reduces contamination of production equipment during production. Furthermore, the combined use of a conjugated diene rubber and an oil having a vapor pressure of 10 Pa or less at 20°C also improves the convergence of the coated fiber. From these perspectives, the vapor pressure of the oil at 20°C is preferably 5 Pa or less, more preferably 1 Pa or less, even more preferably 0.1 Pa or less, and even more preferably 0.01 Pa or less. In the present invention, it is preferable to use a so-called non-volatile oil having a vapor pressure of 10 Pa or less at 20°C. Note that the vapor pressure of the oil at 20°C in the present invention refers to a value calculated from a best-fit curve obtained by applying the Antoine equation to measurements measured by a gas flow method.

[0075] The oil having a vapor pressure of 10 Pa or less at 20°C that can be used in the present invention is not particularly limited as long as it is compatible with the conjugated diene rubber, 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, as well as waxes produced by the Fischer-Tropsch process (gas-to-liquid wax) and mineral oils produced by isomerizing wax.

[0076] 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.

[0077] Examples of synthetic oils include hydrocarbon synthetic oils, ester synthetic oils, and ether synthetic oils. Examples of hydrocarbon synthetic oils include α-olefin oligomers such as polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, and ethylene-propylene copolymer, or hydrogenated products thereof, alkylbenzene, and alkylnaphthalene. Examples of ester synthetic oils include triglycerin fatty acid esters, diglycerin fatty acid esters, monoglycerin fatty acid esters, monoalcohol fatty acid esters, and polyhydric alcohol fatty acid esters. Examples of ether synthetic oils include polyoxyalkylene glycols and polyphenyl ethers. Commercially available synthetic oils include the "Linearene" series manufactured by Idemitsu Kosan Co., Ltd., and "FGC32," "FGC46," and "FGC68" manufactured by ANDEROL. Among these, from the viewpoint of preventing the adhesive composition from causing coating unevenness and improving adhesiveness, triglycerin fatty acid esters, phthalic acid esters, and adipic acid esters are preferred, and 2-ethylhexanoic acid triglyceride and adipic acid esters are more preferred.

[0078] The oil may be one selected from the natural oils and synthetic oils, or a mixture of two or more natural oils, two or more synthetic oils, or one or more natural oils and one or more synthetic oils. In the present invention, from the viewpoint of setting the viscosity of the adhesive composition in an appropriate range and improving workability, mineral oil is preferred, and one or more selected from paraffinic mineral oils and naphthenic mineral oils are more preferred.

[0079] From the viewpoint of safety, the flash point of the oil used in the present invention is preferably 70° C. or higher. From this viewpoint, the flash point of the oil is more preferably 100° C. or higher, even more preferably 130° C. or higher, and even more preferably 140° C. or higher. There is no particular upper limit to the flash point of the oil, but it is preferably 320° C. or lower.

[0080] The oil content in the aqueous adhesive described below is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and even more preferably 2% by mass or more, and is preferably 25% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. More specifically, the oil content in the aqueous adhesive described below is preferably 0.1 to 25% by mass, more preferably 0.5 to 15% by mass, even more preferably 1 to 10% by mass, and even more preferably 2 to 10% by mass.

[0081] Furthermore, in the aqueous adhesive described below, the content of oil per 100 parts by mass of conjugated diene rubber is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, and is preferably 300 parts by mass or less, more preferably 280 parts by mass or less, and even more preferably 250 parts by mass or less, from the viewpoint of improving adhesion to the rubber and improving the convergence of the coated fiber. More specifically, in the aqueous adhesive described below, the content of oil per 100 parts by mass of conjugated diene rubber is preferably 50 to 300 parts by mass, more preferably 60 to 280 parts by mass, and even more preferably 70 to 250 parts by mass.

[0082] [Surfactant] In the present invention, from the viewpoint of enabling the adhesive composition containing the conjugated diene rubber to be stored for a long period of time, a surfactant may be used to prepare an emulsion containing the conjugated diene rubber. The surfactant used in the present invention is not particularly limited, and examples thereof include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are preferred from the viewpoint of compatibility between the adhesive composition and the rubber.

[0083] 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, as well as polyhydric alcohol-type nonionic surfactants such as alkylglycoxides and sucrose fatty acid esters. These nonionic surfactants may be used alone, or, if necessary, two or more types may be used in combination. Commercially available nonionic surfactants include "Adeka Tol TN100," "Adeka Tol PC-6," "Adeka Tol PC-8," "Adeka Tol PC-10," and "Adeka Tol SO-80," manufactured by ADEKA Corporation.

[0084] Examples of cationic surfactants include alkylammonium acetate salts, alkyldimethylbenzylammonium salts, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkylpyridinium salts, oxyalkylene alkylamines, polyoxyalkylene alkylamines, etc. These cationic surfactants may be used alone or, if necessary, in combination of two or more.

[0085] Examples of anionic surfactants include carboxylates of fatty acid soaps and the like, 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, sulfated olefins, and the like, alkylbenzene sulfonates, alkylnaphthalene sulfonates, naphthalene sulfonates, formalin condensates of naphthalene sulfonic acid, and the like, sulfonates such as α-olefin sulfonates, paraffin sulfonates, and sulfosuccinic acid diester salts, and higher alcohol phosphate ester salts. These anionic surfactants may be used alone, or, if necessary, two or more types may be used in combination. If necessary, a nonionic surfactant and an anionic surfactant may be combined.

[0086] Examples of zwitterionic surfactants include alkylcarboxybetaines.

[0087] 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 conjugated diene rubber and oil is good, and a coated fiber with good adhesion to rubber can be obtained. Furthermore, from the viewpoints of safety in the usage environment and operability, it is preferable that the adhesive composition be applied to the fiber as an emulsion. 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 viewpoints of compatibility between conjugated diene rubber and oil and adhesion to rubber, 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 indicating the balance of hydrophilicity and lipophilicity, and is expressed as a value from 0 to 20. For example, it can be calculated by the following formula (I) based on the Griffin method: HLB value = 20 × sum of formula weights of hydrophilic moieties / molecular weight (I) The nonionic surfactant can be identified by detecting and measuring the molecular weight and constitutional units using mass spectrometry. 1 H and13 Since the structure can be detected and measured using C-NMR and identified based on the detected structure, it is possible to determine the HLB value using formula (I) based on the identified information. Note that, as a method for separating the nonionic surfactant from the adhesive composition, for example, a method of fractionating and separating the surfactant by reverse phase liquid chromatography can be mentioned.

[0088] From the viewpoint of improving the stability of the emulsion, the content of the surfactant in the emulsion is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the conjugated diene rubber.

[0089] There are no particular limitations on the method for producing the emulsion, and it is preferable to prepare the emulsion by a mechanical method or a chemical method and use it at a predetermined concentration by dilution or the like. Mechanical methods include methods using a homogenizer, homomixer, disperser mixer, colloid mill, pipeline mixer, high-pressure homogenizer, ultrasonic emulsifier, etc., and these can be used alone or in combination. Chemical methods include various methods such as inversion emulsification, D-phase emulsification, HLB temperature emulsification, gel emulsification, and liquid crystal emulsification, with inversion emulsification being preferred from the perspective of easily obtaining an emulsion with a fine particle size. Furthermore, in order to obtain an emulsion with a fine particle size, it may be preferable to carry out the process while heating at an appropriate temperature (e.g., 30 to 80°C) in order to reduce the viscosity of the conjugated diene rubber.

[0090] In the present invention, for the purpose of increasing the stability of the emulsion, alkaline substances such as sodium hydroxide, potassium hydroxide, and amines may be added as necessary to adjust the pH before use.

[0091] When an alkaline substance is used, the amount of the alkaline substance relative to 100 parts by mass of the 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 is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less.

[0092] [Viscosity of Adhesive Composition at 50°C] The adhesive composition preferably has a viscosity of 500 Pa·s or less, measured at 50°C. When the viscosity is within the above range, the adhesive composition can be efficiently adhered to fibers, and the adhesive composition is less likely to adhere to production equipment, thereby suppressing contamination of the production equipment. From this perspective, the adhesive composition preferably has a viscosity of 250 Pa·s or less, more preferably 100 Pa·s or less, and even more preferably 80 Pa·s or less, measured at 50°C. The lower the viscosity, the better the handling properties and the degree of process contamination. However, from the viewpoint of fiber convergence, the viscosity may be preferably 0.01 Pa·s or more, more preferably 0.03 Pa·s or more, and even more preferably 0.05 Pa·s or more. More specifically, the adhesive composition preferably has a viscosity of 0.01 to 250 Pa·s, more preferably 0.03 to 100 Pa·s, and even more preferably 0.05 to 80 Pa·s, measured at 50°C. The viscosity of the adhesive composition at 50° C. means a viscosity measured using a Brookfield viscometer (B-type viscometer) at 50° C. The rotor and rotation speed during measurement are appropriately set so as to be close to full scale.

[0093] Furthermore, the adhesive composition of the present invention may contain other components in addition to the conjugated diene rubber, oil, crosslinking agent, surfactant, and alkaline substance, as long as the other components do not impair adhesion to the rubber. Examples of such other components include water, other polymers, acids, antioxidants, curing agents, dispersants, pigments, dyes, adhesion aids, and carbon black. When the adhesive composition contains other components, the content of such other components 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, even more preferably 25 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the conjugated diene rubber.

[0094] [Method for producing adhesive composition and aqueous adhesive] The coating in the present invention is obtained, for example, by attaching an aqueous adhesive containing an emulsion containing the conjugated diene rubber, a crosslinking agent, water, and other components as necessary to a fiber, and then drying and heat treating the aqueous adhesive to form a coating containing the adhesive composition and / or a reaction product of the adhesive composition on the fiber surface. There are no particular limitations on the method for producing the aqueous adhesive, and the aqueous adhesive can be produced by mixing the components. Specifically, the aqueous adhesive can be obtained by mixing the emulsion containing the conjugated diene rubber, a crosslinking agent, water, and other components as necessary using a known method, etc.

[0095] The aqueous adhesive may be a one-component system or a two-component system, but is preferably a one-component system, which not only allows for space-saving production facilities but also reduces the environmental impact by shortening the processing steps.

[0096] The adhesive composition used in the present invention can provide coated fibers with excellent adhesion to rubber even without containing formaldehyde or resins derived from formaldehyde, which are harmful to the human body. In the present invention, if the adhesive composition contains a resin derived from formaldehyde, examples of such resins include resorcinol / formaldehyde resins, phenol / formaldehyde resins, melamine / formaldehyde resins, and derivatives thereof. If the adhesive composition contains the formaldehyde component (formaldehyde or a resin derived from formaldehyde), the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the conjugated diene rubber. It is particularly preferable that the adhesive composition be substantially free of the formaldehyde component. The formaldehyde component content can be measured by extracting the adhesive composition from the coated fiber with a solvent such as toluene and then using HPLC or the like.

[0097] <Fiber> The fiber used in the coated fiber of the present invention is not particularly limited, but hydrophilic fibers are preferred from the viewpoint of affinity with the adhesive composition. In the present invention, the term "fiber" includes not only short fibers and long fibers, but also forms such as nonwoven fabrics, woven fabrics, knitted fabrics, felts, and sponges.

[0098] Examples of hydrophilic synthetic fibers include synthetic fibers made of thermoplastic resins having hydrophilic functional groups such as hydroxyl groups, carboxyl groups, sulfonic acid groups, and amino groups, and / or hydrophilic bonds such as amide bonds. Specific examples of such thermoplastic resins include polyvinyl alcohol resins, polyamide resins (aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, and polyamide 9C (a polyamide composed of nonanediamine and cyclohexanedicarboxylic acid); semi-aromatic polyamides synthesized from aromatic dicarboxylic acids and aliphatic diamines, such as polyamide 9T (a polyamide composed of nonanediamine and terephthalic acid); fully aromatic polyamides synthesized from aromatic dicarboxylic acids and aromatic diamines, such as polyparaphenylene terephthalamide), and polyacrylamide resins. Among these, polyvinyl alcohol resins and polyamide resins are preferred. The hydrophilic synthetic fibers may be used alone or in combination of two or more types. These hydrophilic synthetic fibers may be further subjected to a hydrophilization treatment, which will be described later, in order to further enhance the hydrophilicity.

[0099] Examples of hydrophilic natural fibers include natural cellulose fibers such as wood pulp (e.g., kraft pulp) and non-wood pulp (e.g., cotton pulp and straw pulp). Examples of hydrophilic regenerated fibers include regenerated cellulose fibers such as rayon, lyocell, cupra, and polynosic. These natural fibers and regenerated fibers may be used alone or in combination of two or more. Furthermore, these hydrophilic natural fibers and regenerated fibers may be further subjected to a hydrophilization treatment described below to further enhance their hydrophilicity.

[0100] The hydrophilic fiber may have at least a hydrophilic surface, and may be, for example, a hydrophobic fiber whose surface has been hydrophilized, or a core-sheath composite fiber in which a hydrophobic resin is used as the core and a hydrophilic resin is used as the sheath. Examples of hydrophilic resins that constitute the sheath are described in the description of hydrophilic synthetic fibers. Examples of hydrophobic fibers made of hydrophobic resins include polyolefin fibers such as polyethylene and polypropylene, polyester fibers such as polyethylene terephthalate, and wholly aromatic polyester fibers. Among these, polyester fibers are preferred.

[0101] The hydrophilization treatment is not particularly limited as long as it is a treatment that chemically or physically imparts hydrophilic functional groups to the fiber surface. For example, the hydrophilization treatment can be carried out by a method in which hydrophobic fibers made of the hydrophobic resin are modified with a compound containing a hydrophilic functional group such as an isocyanate group, an epoxy group, a hydroxy group, an amino group, an ether group, an aldehyde group, a carbonyl group, a carboxy group, or a urethane group, or a derivative thereof, or by a method in which the surface is modified by electron beam irradiation.

[0102] From the viewpoint of being used as a covering fiber, the hydrophilic fibers used in the present invention are preferably synthetic fibers and regenerated fibers, and 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. In the present invention, the use of hydrophilic fibers, particularly when the conjugated diene rubber contained in the adhesive composition is a modified conjugated diene rubber, exhibits a strong affinity effect with the hydrophilic fibers, and the adhesive composition and the hydrophilic fibers are firmly bound together, thereby making it possible to improve the adhesive strength to the rubber.

[0103] From the viewpoint of suitably using the coated fiber of the present invention for automobile hoses, particularly automobile brake oil hoses, polyvinyl alcohol-based fibers that can be suitably used include those commercially available from Kuraray Co., Ltd. under the trade name "Vinylon" and having a single fiber fineness of about 0.1 to 30 dtex. In the present invention, one type of fiber may be used alone, or two or more types may be used in combination.

[0104] The fibers used for the coated fiber of the present invention may be monofilaments or multifilaments, with multifilaments being preferred. 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.

[0105] [Method for producing coated fiber] There are no particular limitations on the method for producing the coated fiber of the present invention, but the coated fiber of the present invention is preferably one obtained by applying an aqueous adhesive containing the conjugated diene rubber to the fiber and then heating it. More specifically, the coated fiber of the present invention is more preferably one obtained by a method including the steps of applying to a fiber an aqueous adhesive comprising a mixture of an emulsion of the conjugated diene rubber, the oil, and the surfactant, a crosslinking agent, water, and optionally other components, and then drying and heating the aqueous adhesive that has been applied to the fiber. Producing a coated fiber by the method of applying an aqueous adhesive to a fiber and then heating it is preferred because the adhesive composition formed by drying the aqueous adhesive on the fiber surface further reacts with heat to produce reaction products, and a coating containing these reaction products covers the fiber. The reaction product is preferably one in which two conjugated diene rubbers are bonded together via a crosslinking agent, and / or one in which the conjugated diene rubber and the fiber are bonded together via a crosslinking agent. More specifically, the reaction product is preferably one in which two conjugated diene rubbers are bonded together via a crosslinking agent, and / or one in which the conjugated diene rubber and the crosslinking agent are bonded together. By bonding these reaction products with the fiber, the adhesive composition is more firmly fixed to the fiber surface, improving adhesion to the rubber. That is, when the reaction product contains two conjugated diene rubbers bonded together via a crosslinking agent, the reaction product contains a crosslinked product with an appropriate molecular weight, improving process contamination while maintaining adhesion. Furthermore, when the reaction product contains one in which the conjugated diene rubber and the fiber are bonded together via a crosslinking agent (more specifically, when the reaction product contains one in which the conjugated diene rubber and the crosslinking agent are bonded together, and the adhesive composition is more firmly fixed to the fiber surface), adhesion to the rubber is particularly improved. As a more specific method for producing the coated fiber of the present invention, from the viewpoint of improving adhesion to rubber, method (I) is preferred, in which a coating containing one or more selected from the group consisting of the adhesive composition and reaction products of the adhesive composition is formed on the surface of the fiber.

[0106] [Method (I)] From the viewpoint of improving adhesion to rubber, method (I) is preferably a method including the following step I-1, but it is not limited to aqueous adhesives, and other solvent-based (organic solvent-based) adhesives can also be used. Step I-1: A step of attaching an aqueous adhesive to the surface of a fiber

[0107] In step I-1, the method for applying the aqueous adhesive to the fibers is not particularly limited, and examples thereof include a method in which the aqueous adhesive is applied as is, a method in which a solvent is added to the aqueous adhesive as necessary, etc. The method for applying the aqueous adhesive is preferably carried out by one or more methods selected from immersion, roll coater, oiling roller, oiling guide, nozzle (spray) application, brush application, etc.

[0108] In the present invention, the coated fiber of the present invention can be obtained by applying the aqueous adhesive to the fiber and then allowing it to soak for about 3 to 10 days at room temperature of about 20°C. However, in some cases, the following step I-2 may be performed. Step I-2: A step of heat-treating the fiber to which the aqueous adhesive obtained in step I-1 has been applied. The heat treatment in step I-2 is preferably carried out at a treatment temperature of 100 to 200°C for a treatment time of 0.1 seconds to 2 minutes. Because the conjugated diene rubber contained in the adhesive composition has reactive multiple bonds, the heat treatment in the presence of oxygen is preferably carried out at 200°C or less, and more preferably at 175°C or less. When the heat treatment temperature is within the above range, the conjugated diene rubber does not react excessively, and a coated fiber that satisfies the above conditions (1) and (2) can be obtained. As a result, a coated fiber with excellent adhesion to rubber can be obtained. From the same viewpoint, the heat treatment time is preferably 90 seconds or less, more preferably 60 seconds or less, and even more preferably 45 seconds or less, and may be 0.1 seconds or more, 0.2 seconds or more, or 0.5 seconds or more.

[0109] In the coated fiber of the present invention, the amount of the coating attached is preferably 0.01 to 10.0 parts by mass, more preferably 0.1 to 5.0 parts by mass, and even more preferably 1.0 to 3.0 parts by mass, per 100 parts by mass of the fiber used as the raw material, from the viewpoint of improving the adhesion between the coated fiber and the rubber.

[0110] The coated fiber of the present invention comprises the fiber and a coating containing the adhesive composition and / or its reaction product. The coating in the coated fiber of the present invention may contain other components in addition to the adhesive composition and / or its reaction product. Examples of other components include crosslinkers, acids, bases, inorganic salts, organic salts, pigments, dyes, antioxidants, polymerization initiators, and plasticizers. From the viewpoints of improving adhesion to rubber and reinforcing strength, the total content of the fiber and the adhesive composition and / or its reaction product in the coated fiber is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0111] The content of the coating in the coated fiber of the present invention is preferably 0.1 to 20.0 parts by mass, more preferably 0.3 to 15.0 parts by mass, and even more preferably 0.5 to 10.0 parts by mass, per 100 parts by mass of the fiber. The content of the coating in the coated fiber can be determined by the method described in the Examples. Furthermore, from the viewpoint of more easily achieving the effects of the present invention, the total content of the adhesive composition and / or its reaction product in the coating is preferably 1 to 100% by mass, more preferably 10 to 80% by mass, and even more preferably 20 to 60% by mass. From the same viewpoint, the content of the conjugated diene rubber in the coating is preferably 1 to 90% by mass, more preferably 5 to 75% by mass, and even more preferably 10 to 50% by mass. The content of the conjugated diene rubber in the coating can be determined by the method described in the Examples.

[0112] <Physical Properties of the Covered Fiber> The covered fiber preferably has a single filament fineness of 0.1 to 30 dtex as the raw fiber, and is more preferably a multifilament. The single filament fineness of the raw fiber may be less than 0.1 dtex, but is difficult to produce industrially, so it is preferably 0.1 dtex or more. Furthermore, if the single filament fineness of the raw fiber is 30 dtex or less, the surface area of ​​the fiber when made into a covered fiber will be large, thereby improving adhesion to rubber. From this viewpoint, the covered fiber of the present invention is preferably a multifilament, and the single filament fineness is preferably 0.3 dtex or more, more preferably 0.5 dtex or more, and even more preferably 1 dtex or more, and preferably 20 dtex or less, more preferably 15 dtex or less, and even more preferably 10 dtex or less. More specifically, the single filament fineness of the raw fiber of the coated fiber of the present invention is preferably 0.3 to 20 dtex, more preferably 0.5 to 15 dtex, and even more preferably 1 to 10 dtex.

[0113] The rubber adhesion of the coated fiber of the present invention is preferably 15.0 N / 25.4 mm or more, more preferably 20.0 N / 25.4 mm or more, even more preferably 25.0 N / 25.4 mm or more, even more preferably 30.0 N / 25.4 mm or more, and typically 200 N / 25.4 mm or less. More specifically, the rubber adhesion of the coated fiber of the present invention is preferably 15.0 to 200 N / 25.4 mm, more preferably 20.0 to 200 N / 25.4 mm, even more preferably 25.0 to 200 N / 25.4 mm, and even more preferably 30.0 to 200 N / 25.4 mm. When the rubber adhesion of the coated fiber is equal to or greater than the above-mentioned lower limit, woven fabrics, knitted fabrics, and molded articles with excellent reinforcing strength can be obtained. The rubber adhesion of the coated fiber can be measured by the method described in the Examples.

[0114] 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 knitted fabric to be bonded to rubber. It can also be used as a coated fiber to be embedded in resin, cement, etc.

[0115] [Molded Product] The molded product of the present invention is not particularly limited as long as it uses the coated fiber. Among them, a molded product using the coated fiber and a rubber component (hereinafter also referred to as a "rubber molded product") is particularly preferred because the coated fiber has excellent adhesion to rubber. From the viewpoint of maintaining the shape of the rubber, the coated fiber used in the rubber molded product is preferably used as a woven or knitted fabric at least partially containing the coated fiber, 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.

[0116] The rubber molded article can be used as a component for rubber products such as tires (e.g., automobile tires), belts (e.g., conveyor belts, timing belts), hoses, and vibration-proof rubber, among others, and is more preferably used as a tire, belt, or hose. The automobile tire can be used for various components made of composite materials of coated fibers and rubber components, such as belts, carcass plies, breakers, and bead tapes. The hose can be used for transporting various fluids in various applications, and is suitable as a hose for transporting fluids in automobiles, for example. It is particularly preferred for use as a hose for transporting liquid fuels, brake oil, and refrigerants in automobiles, and is more preferably used as a brake oil hose in automobiles.

[0117] The rubber molded article is preferably molded using the coated fiber and a rubber composition obtained by compounding a rubber component with compounding agents typically used in the rubber industry. The rubber component is not particularly limited, but examples include NR (natural rubber), IR (polyisoprene rubber), BR (polybutadiene rubber), SBR (styrene-butadiene rubber), NBR (nitrile rubber), EPM (ethylene-propylene copolymer rubber), EPDM (ethylene-propylene-non-conjugated diene copolymer rubber), IIR (butyl rubber), halogenated butyl rubber, and CR (chloroprene rubber). Of these, NR, IR, BR, SBR, EPDM, and CR are preferably used, with EPDM being more preferred. These rubber components may be used alone or in combination of two or more. For tire applications, rubbers commonly used in the tire industry can be used. Of these, natural rubber alone or a combination of natural rubber and SBR is preferred. When natural rubber and SBR are combined, the mass ratio of natural rubber to SBR (natural rubber / SBR) is preferably in the range of 50 / 50 to 90 / 10, from the viewpoint of suppressing deterioration in physical properties due to reversion of the rubber.

[0118] Examples of the natural rubber include natural rubbers commonly used in the tire industry, such as TSR (Technically Specified Rubber) including SMR (Malaysian TSR), SIR (Indonesian TSR), and STR (Thai TSR), and RSS (Ribbed Smoked Sheet), as well as modified natural rubbers such as high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, and grafted natural rubber.

[0119] The SBR may be any SBR commonly used in tires, but specifically, the styrene content is preferably 0.1 to 70 mass%, more preferably 5 to 50 mass%, and even more preferably 15 to 35 mass%, and the vinyl content is preferably 0.1 to 60 mass%, and more preferably 0.1 to 55 mass%.

[0120] The weight-average molecular weight (Mw) of the SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and even more preferably 200,000 to 1,500,000. Within this range, both processability and mechanical strength can be achieved. The weight-average molecular weight of the SBR is the weight-average molecular weight calculated in terms of polystyrene as determined by gel permeation chromatography (GPC). The SBR may be a modified SBR in which a functional group has been introduced into the SBR, provided that the effects of the present invention are not impaired. Examples of functional groups include an amino group, an alkoxysilyl group, a hydroxy group, an epoxy group, and a carboxy group.

[0121] The rubber composition may further contain a filler in addition to the rubber component. Examples of the filler include inorganic fillers such as carbon black, silica, clay, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, titanium oxide, glass fiber, fibrous filler, and glass balloons; and organic fillers such as resin particles, wood flour, fibrous filler, and cork powder. The inclusion of such a filler in the rubber composition makes it possible to improve physical properties such as mechanical strength, heat resistance, and weather resistance, adjust hardness, and increase the amount of rubber. Among the fillers, carbon black and silica are preferred from the viewpoint of improving physical properties such as mechanical strength.

[0122] Examples of the carbon black include furnace black, channel black, thermal black, acetylene black, and ketjen black. Among these carbon blacks, 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 5 to 100 nm, more preferably 5 to 80 nm, and even more preferably 5 to 70 nm. The average particle size of the carbon black can be determined by measuring the particle diameters using a transmission electron microscope and calculating the average value.

[0123] Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Of these, wet silica is preferred. The average particle size of the silica is preferably 0.5 to 200 nm, more preferably 5 to 150 nm, and even more preferably 10 to 100 nm. The average particle size of the silica can be determined by measuring the particle diameters using a transmission electron microscope and calculating the average value.

[0124] In the rubber composition, the amount of the filler per 100 parts by mass of the rubber component 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. When a filler other than silica and carbon black is used as the filler, the amount 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. These fillers may be used alone or in combination of two or more.

[0125] 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, quinone and quinone dioxime derivatives, halogen compounds, aldehyde compounds, alcohol compounds, epoxy compounds, metal halides and organometallic halides, and silane compounds. These crosslinking agents may be used alone or in combination of two or more. From the viewpoint of the mechanical properties of the crosslinked product, the content of the crosslinking agent is typically 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.

[0126] When the rubber composition contains sulfur or a sulfur compound as a crosslinking agent for crosslinking (vulcanizing) the rubber component, the rubber composition may further contain a vulcanization accelerator. Examples of the vulcanization accelerator include guanidine compounds, sulfenamide compounds, thiazole compounds, thiuram compounds, thiourea compounds, dithiocarbamic acid compounds, aldehyde-amine compounds, aldehyde-ammonia compounds, imidazoline compounds, and xanthate compounds. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator is typically 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0127] When the rubber composition contains 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 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.

[0128] When the rubber composition contains silica as a filler, it is preferable that the rubber composition further contains a silane coupling agent. Examples of the silane coupling agent include sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, and chloro compounds. These silane coupling agents may be used alone or in combination of two or more. The silane coupling agent is preferably contained in an amount of 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, and reinforcement are improved.

[0129] The rubber composition may contain, as needed, a softener such as silicone oil, aromatic oil, TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), process oil such as 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, fluidity, etc., within a range that does not impair the effects of the present invention. When the rubber composition contains the process oil as a softener, the content thereof is preferably less than 50 parts by mass per 100 parts by mass of the rubber component.

[0130] The rubber composition may contain additives such as antioxidants, waxes, antioxidants, lubricants, light stabilizers, scorch inhibitors, processing aids, colorants such as pigments and dyes, flame retardants, antistatic agents, matting agents, antiblocking agents, UV absorbers, mold release agents, foaming agents, antibacterial agents, antifungal agents, and fragrances, as needed, to improve weather resistance, heat resistance, and oxidation resistance, as long as the effects of the present invention are not impaired. Examples of antioxidants include hindered phenol compounds, phosphorus compounds, lactone compounds, and hydroxyl compounds. Examples of antioxidants include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, and phosphorus compounds. These additives may be used alone or in combination.

[0131] As a method for producing the rubber molded body, for example, the coated fiber is embedded in the unvulcanized rubber composition, and the rubber composition is then vulcanized to obtain a molded body in which the fiber and rubber component are bonded via the adhesive composition and / or its reaction product.

[0132] Examples of the automotive brake oil hose include one having an inner rubber layer and an outer rubber layer, with one or two reinforcing layers made of the coated fibers between the inner and outer rubber layers. Examples of rubber components constituting the inner and outer rubber layers include those described above. Among these, examples of rubber components constituting the inner rubber layer include EPDM, SBR, etc., and examples of rubber components constituting the outer rubber layer include EPDM, CR, etc. The reinforcing layer can be formed by braiding the coated fibers. A method for manufacturing the brake oil hose includes forming a reinforcing layer (first reinforcing layer) made of braided coated fibers on the outer surface of the inner rubber layer. When forming two reinforcing layers, an intermediate rubber layer may be further formed on the outer surface of the first reinforcing layer, and then forming a reinforcing layer (second reinforcing layer) made of braided coated fibers on the outer surface of the intermediate rubber layer. The hose can then be manufactured by forming the outer rubber layer on the outer surface of the reinforcing layer (first reinforcing layer) and vulcanizing the outer rubber layer. The vulcanization temperature can be appropriately selected depending on the type of constituent material of each layer of the brake oil hose, but it is preferably 200°C or less from the viewpoint of suppressing deterioration of the rubber and the coated fiber and improving the adhesive strength between the rubber and the coated fiber.

[0133] 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.

[0134] [Production of Liquid 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 132 g of n-butyllithium (17 mass % hexane solution) were charged. The temperature was raised to 50°C, and then 1,260 g of 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)).

[0135] Production Example 2: Production of Modified Conjugated Diene Rubber (A-2) 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 autoclave was then heated to 50°C, and 1,260 g of butadiene was gradually added thereto while stirring to maintain the polymerization temperature at 50°C. Polymerization was then carried out for 1 hour. Methanol was then added to terminate the polymerization reaction, yielding a polymer solution. Water was added to the resulting polymer solution, followed by stirring, and the polymer solution was washed with water. After stirring was terminated, separation of the polymer solution phase and the aqueous phase was confirmed, followed by separation of the water. The polymer solution after washing was vacuum dried at 70°C for 24 hours to yield unmodified liquid polybutadiene (A'-2). Subsequently, 500 g of the obtained unmodified liquid polybutadiene (A'-2) 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-2)).

[0136] Production Example 3: Production of Modified Conjugated Diene Rubber (A-3) A thoroughly dried 5 L autoclave was purged with nitrogen, and 1,260 g of hexane and 28.0 g of n-butyllithium (17% by mass hexane solution) were charged. The autoclave was then heated to 50°C, and 1,260 g of butadiene was gradually added thereto while controlling the polymerization temperature to 50°C under stirring conditions, 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 then washed with water. After stirring was stopped, it was confirmed that the polymer solution phase and the aqueous phase had separated, and the water was then separated. The polymer solution after washing was vacuum dried at 70°C for 24 hours to yield unmodified liquid polybutadiene (A'-3). Subsequently, 500 g of the obtained unmodified liquid polybutadiene (A'-3) 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-3)).

[0137] [Production of Liquid Unmodified Conjugated Diene Rubber] Production Example 4: Production of Unmodified Conjugated Diene Rubber (L-1) A thoroughly dried 5 L autoclave was purged with nitrogen, and 1,260 g of hexane and 90.0 g of n-butyllithium (17 mass % hexane solution) were charged. The temperature was raised to 50°C, and then 1,260 g of 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, and 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 unmodified liquid polybutadiene (L-1).

[0138] The methods for measuring and calculating the various physical properties of the liquid conjugated diene rubber and the like are as follows. The results are shown in Table 1.

[0139] <Method of measuring weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn)> The Mw, Mn, and Mw / Mn of the conjugated diene rubber were determined as standard polystyrene equivalent values ​​by gel permeation chromatography (GPC). The measurement device and conditions were as follows: Device: GPC device "GPC8020" manufactured by Tosoh Corporation Separation column: "TSKgel G4000HXL" manufactured by Tosoh Corporation Detector: "RI-8020" manufactured by Tosoh Corporation Eluent: tetrahydrofuran Eluent flow rate: 1.0 ml / min Sample concentration: 5 mg / 10 ml Column temperature: 40°C

[0140] <Method for Measuring Melt Viscosity> The melt viscosity of the conjugated diene rubber at 38°C was measured using a Brookfield viscometer (manufactured by Brookfield Engineering Labs. Inc.).

[0141] <Method for measuring glass transition temperature> 10 mg of conjugated diene rubber was placed in an aluminum pan, and a thermogram was obtained by differential scanning calorimetry (DSC) at a temperature rise rate of 10°C / min. The value at the peak top of the DSC was taken as the glass transition temperature.

[0142] <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 modified conjugated diene rubber was calculated from the equivalent weight (g / eq) of the hydrogen-bonding functional groups of the modified conjugated diene rubber and the number average molecular weight Mn in terms of styrene, using the following formula: Average number of hydrogen-bonding functional groups per molecule = [(number average molecular weight (Mn)) / (molecular weight of styrene units) × (average molecular weight of conjugated diene and other monomer units other than conjugated diene contained as necessary)] / (equivalent weight of hydrogen-bonding functional groups) The method for calculating the equivalent weight of the hydrogen-bonding functional groups was selected appropriately depending on the type of hydrogen-bonding functional group.

[0143] The average number of hydrogen-bonding functional groups per molecule of the monomethyl maleate-modified conjugated diene rubber was calculated by determining the acid value of the monomethyl maleate-modified conjugated diene rubber and calculating the equivalent weight (g / eq) of the hydrogen-bonding functional groups from the acid value. After the modification reaction, the sample was washed four times with methanol (5 mL per 1 g of sample) to remove impurities such as antioxidants, and then dried under reduced pressure at 80°C for 12 hours. After the pretreatment, 3 g of the sample was dissolved in 180 mL of toluene and 20 mL of ethanol, and then neutralized with a 0.1 N potassium hydroxide ethanol solution. The acid value was calculated using the following formula: Acid value (mg KOH / g) = (A - B) x F x 5.611 / S A: Amount (mL) of 0.1 N potassium hydroxide ethanol solution added required for neutralization B: Amount (mL) of 0.1 N potassium hydroxide ethanol solution added to a blank containing no sample F: Potency of 0.1 N potassium hydroxide ethanol solution S: Mass (g) of weighed sample

[0144] From the acid value, the mass of hydrogen-bonding functional groups contained per 1 g of the monomethyl maleate-modified conjugated diene rubber was calculated using the following formula, and further, the mass other than functional groups (polymer main chain mass) contained per 1 g of the monomethyl maleate-modified conjugated diene rubber was calculated. Then, the equivalent weight (g / eq) of the hydrogen-bonding functional group was 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])

[0145]

[0146] <Preparation of Emulsion> Preparation Example 1: Preparation of emulsion (E-1) of modified conjugated diene rubber (A-1) 50 g of modified conjugated diene rubber (A-1) and 2-ethylhexanoic acid triglyceride (hereinafter also referred to as "EHTG"; product name "Excepal TGO", manufactured by Kao Corporation; vapor pressure at 20°C: 1.7 × 10) were mixed. -7The mixture was stirred with 100 g of the modified conjugated diene rubber (A-1) and oil (E-1) until uniformly mixed. 9 g of a nonionic surfactant (HLB value = 12.4, trade name "Adekataol PC-8", ADEKA Corporation) was then added and stirred for 5 minutes. 341 g of a 0.06 mol / L aqueous ammonia solution was then added little by little with stirring, to obtain an emulsion (E-1) of a mixture of the modified conjugated diene rubber (A-1) and oil.

[0147] Preparation Example 2: Preparation of emulsion (E-2) of modified conjugated diene rubber (A-2) An emulsion (E-2) of a mixture of modified conjugated diene rubber (A-2) and oil was obtained in the same manner as in Preparation Example 1, except that the type of modified conjugated diene rubber used was A-2.

[0148] Preparation Example 3: Preparation of emulsion (E-3) of modified conjugated diene rubber (A-3) An emulsion (E-3) of a mixture of modified conjugated diene rubber (A-3) and oil was obtained in the same manner as in Preparation Example 1, except that the type of modified conjugated diene rubber used was A-3.

[0149] Preparation Example 4: Preparation of emulsion (E-4) of modified conjugated diene rubber (A-2) An emulsion (E-4) of a mixture of modified conjugated diene rubber (A-2) and oil was obtained in the same manner as in Preparation Example 2, except that the surfactants used were two types of nonionic surfactants (trade names "Akator TN-40" and "Akator LB-53B", ADEKA Corporation).

[0150] Preparation Example 5: Preparation of emulsion (E-5) by mixing two types of modified conjugated diene rubbers (A-2, A-3) An emulsion (E-5) of a mixture of two types of modified conjugated diene rubbers (A-2, A-3) and oil was obtained in the same manner as in Preparation Example 1, except that the types of modified conjugated diene rubbers used were A-2 and A-3, and that the amounts of A-2 and A-3 were 12.5 g and 37.5 g, respectively.

[0151] Preparation Example 6: Preparation of emulsion (E-6) by mixing two types of modified conjugated diene rubbers (A-2, A-3) An emulsion (E-6) of a mixture of two types of modified conjugated diene rubbers (A-2, A-3) and oil was obtained in the same manner as in Preparation Example 5, except that the amounts of the two types of modified conjugated diene rubbers A-2 and A-3 used were 37.5 g of A-2 and 12.5 g of A-3.

[0152] Preparation Example 7: Preparation of emulsion (E-7) of unmodified conjugated diene rubber (L-1) An emulsion (E-7) of a mixture of unmodified conjugated diene rubber (L-1) and oil was obtained in the same manner as in Preparation Example 1, except that unmodified conjugated diene rubber L-1 was used instead of the modified conjugated diene rubber.

[0153] Example 1 An aqueous adhesive (AD-1) was prepared by mixing emulsion (E-1) prepared by the method described above so as to have the composition shown in Table 2 with an isocyanate compound (trade name "SU268-A" manufactured by Meisei Chemical Industry Co., Ltd.), an epoxy resin (trade name "Denacol EX-512" manufactured by Nagase ChemteX Corporation), and water. Polyvinyl alcohol (PVA) fibers (trade name "Kuralon 1239" with a total fineness of 1,330 dtex and a single filament fineness of 6.65 dtex manufactured by Kuraray Co., Ltd.) were then immersed in the aqueous adhesive and squeezed with a roller. The resulting fibers were then dried at 115°C for 30 seconds, further heat-treated at 150°C for 30 seconds, and wound up to produce PVA fibers coated with a coating containing one or more selected from the group consisting of adhesive compositions and / or reaction products of adhesive compositions.

[0154] Examples 2 to 7 and Comparative Examples 1 to 3 PVA fibers coated with a coating material were prepared in the same manner as in Example 1, except that the composition of the water-based adhesive was changed according to the description in Table 2.

[0155]

[0156] <Measurement of Fineness of Coated Fiber> The coated fiber to which the adhesive composition was applied was sampled at a length of 100 m, and its mass was measured. The fineness (unit: dtex) of the coated fiber to which the adhesive composition was applied was calculated by multiplying (mass (unit: g) of 100 m length) by 100.

[0157] <Amount of Coating Adhesion (Parts by Mass) Per 100 Parts by Mass of Fiber> Before application of the adhesive composition, a fiber length of 100 m was sampled, and the mass (mass before treatment) was measured after treatment at 105°C for 4 hours. Next, the same length of fiber was sampled after application of the adhesive composition and drying / heat treatment as described in each example, and the mass (mass before treatment) was also measured after treatment at 105°C for 4 hours. The amount of adhesive composition (coating) adhering per 100 parts by mass of fiber before application of the adhesive composition was calculated by [(mass after treatment) - (mass before treatment)] x 100 / (mass before treatment). In Table 2, the content (parts by mass) of each component in the aqueous adhesive was calculated from the mass ratio of each component (conjugated diene rubber, EHTG, isocyanate compound, epoxy resin) in the aqueous adhesive.

[0158] <GPC Analysis> 10 g of PVA fibers bearing a coating containing at least one selected from the group consisting of the adhesive compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 3 and reaction products of the adhesive compositions were immersed in THF (tetrahydrofuran) to extract the coating from the fiber surface. The extract was concentrated using an evaporator and then vacuum-dried at 40°C for 16 hours, and then redissolved in THF to adjust the concentration to 0.1 w / v%. This solution was used for GPC analysis under the following conditions. The molecular weight distribution curve obtained from the RI detector was determined using polymethyl methacrylate (PMMA) as a calibration curve standard and the analysis software attached to the analyzer. The obtained detection data was extracted and analyzed within the detection time range of 8.1 to 10.6 minutes.

[0159] <GPC analysis conditions> Measurement equipment: OMNISEC RESOLVE, OMNISEC REVEAL (Malvern) Sample concentration: 0.1 w / v% Mobile phase solvent: THF Injection volume: 100 μL Flow rate: 1.0 mL / min Measurement temperature: 40°C Filtration: 0.45 μm filter Column: KF806L (Shodex) Detector: RI detector included with the equipment Equipment calibration sample: PMMA Analysis software: OMNISEC software

[0160] <Peak Analysis> In the molecular weight distribution curve obtained by GPC analysis, it was determined whether or not a peak existed in the molecular weight range of 2,600 to 19,000, and if a peak existed, the molecular weight was calculated.

[0161] <Analysis of Area Ratio> In the molecular weight distribution curve obtained by GPC analysis, the area under the curve in the molecular weight range of 2,600 to 19,000 was designated as (A), and the area under the curve in the molecular weight range of 19,000 to 540,000 was designated as (B). The peak area values ​​calculated when analyzing these molecular weight ranges using the analysis software (OMNISEC software) attached to the analyzer were designated as (A) and (B), respectively, and the area ratio [(A) / (B)] was calculated.

[0162] <Rubber Adhesion Strength> Evaluation sheets were prepared for the coated fibers obtained in Examples 1 to 7 and Comparative Examples 1 to 3 by the method described below. The force (N / 25.4 mm) required to T-peel the coated fiber from the rubber (peel at an angle of 180°) was then measured and evaluated as rubber adhesion strength. The results are shown in Table 3. In the evaluation results for rubber adhesion strength, a higher numerical value indicates greater adhesion between the coated fiber and rubber. The evaluation sheets were prepared as follows.

[0163] Preparation of Evaluation Sheets The coated fibers prepared in Examples 1 to 7 and Comparative Examples 1 to 3 were twisted at 80 T / m, and 38 fibers were arranged and fixed on masking tape in a curtain-like pattern so that the fibers did not overlap. This was then overlapped with an unvulcanized rubber composition (hereinafter also referred to as "EPDM unvulcanized rubber"; width 25.4 mm, length 240 mm) containing EPDM rubber ("Esprene 501A" manufactured by Sumitomo Chemical Co., Ltd.) as the main component, which was prepared according to the following formulation using EPDM rubber (the length of the overlapped portion of the fiber and EPDM unvulcanized rubber was 190 mm). The fibers were then twisted at 150°C under a pressure of 20 kg / cm. 2 The mixture was press-vulcanized for 30 minutes under the conditions of 1.0 to 1.5° C. for 30 minutes to prepare a sheet for evaluation.

[0164] (Composition of EPDM unvulcanized rubber) EPDM rubber: 100 parts by mass Filler (carbon black): 60 parts by mass Softener (paraffin-based process oil): 20 parts by mass Crosslinking agent (sulfur powder): 1.5 parts by mass Vulcanization aid (zinc oxide type 2, stearic acid): 6 parts by mass Vulcanization accelerator (thiazole-based, thiuram-based): 1.5 parts by mass

[0165] <Process contamination> In Examples 1 to 7 and Comparative Examples 1 to 3, the aqueous adhesive was applied to each fiber as described in each example, and the coated PVA fiber (5 kg) was wound up. After drying and heat treatment, the degree of contamination (gum-up) of the holding roller through which the coated fiber passed was evaluated according to the following evaluation criteria. The results are shown in Table 3.

[0166] Evaluation criteria E (excellent): There is no or very little roller contamination due to gum-up, and spinning operability is good. G (good): There is little roller contamination due to gum-up, and there are no problems with spinning operability. B (bad): There is significant roller contamination due to gum-up, and there are "single yarn take-up" and "winding" during spinning, and there are problems with spinning operability.

[0167] <Convergence> The coated fibers (multifilament fibers with a total fineness of 1,330 dtex and a single yarn fineness of 6.65 dtex) produced in Examples 1 to 7 and Comparative Examples 1 to 3 were cut to a length of 120 cm, and the upper end of the coated fiber was tied to a hook attached to a wall surface to secure it. A 1 kg weight was tied to the lower end of the fixed coated fiber so that the weight did not contact the ground, and the fiber was left suspended in mid-air. The fiber was cut at a position 100 cm from the knot on the upper side of the fiber tied to the wall surface, and the length of disruption in the convergence of the coated fiber was measured from the lower end after cutting. The results are shown in Table 3. In this evaluation, a shorter disruption length indicates better convergence.

[0168] <Residual fiber strength after F / M friction test> The coated fibers obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were twisted at 80 T / m and subjected to testing. The coated fibers were set in the metal abrasion tester shown in FIG. 1 , and the operating table was moved back and forth 1,000 times to prepare samples damaged by friction with metal. The breaking strength of the prepared samples was measured, and the remaining strength after metal friction was calculated as [breaking strength after metal friction] / [breaking strength before metal friction]×100. The results are shown in Table 3. In this evaluation, a higher remaining strength indicates less damage due to abrasion.

[0169]

[0170] As is clear from the results of the Examples and Comparative Examples, the present invention enables the production of coated fibers with excellent adhesion to rubber. Furthermore, the present invention also enables the production of coated fibers with excellent convergence and strength after friction, and molded articles using the same, which can be produced while suppressing contamination of production equipment. All Examples demonstrated practically effective adhesion and residual fiber strength. Furthermore, convergence, which affects processability, also demonstrated satisfactory values, with Examples 2, 3, and 7 demonstrating particularly excellent convergence. Furthermore, with regard to process contamination, Examples 1 to 4 and 7, which used only low-molecular-weight conjugated diene rubber, showed better results than Examples 5 and 6, which contained two conjugated diene rubbers with different molecular weights. This suggests the influence of the high-molecular-weight conjugated diene rubber, which is presumed to have a more complex crosslinked structure. Example 4, which exhibits a high amount of coating material attached, demonstrated low process contamination and good results. Adhesion was comparable to the other Examples.

[0171] 1: Fiber fixing base 2: Moving table 3: Mirror chrome plated guide 4: Free roller 5: Load (165 g) 6: Moving width of moving table (90 mm) 7: Coated fiber sample

Claims

1. A coated fiber obtained by coating a fiber with a coating material containing one or more selected from the group consisting of an adhesive composition containing a conjugated diene rubber and a reaction product of said adhesive composition, wherein the molecular weight distribution curve of the coating material obtained by GPC analysis satisfies both of the following conditions (1) and (2): <Condition (1)> It has at least one peak in the molecular weight range of 2,600 to 19,000. <Condition (2)> When the area under the curve in the molecular weight range of 2,600 to 19,000 is (A) and the area under the curve in the molecular weight range of 19,000 to 540,000 is (B), the area ratio [(A) / (B)] is 0.5 to 9.

0.

2. The coated fiber of claim 1 , wherein the adhesive composition further comprises a crosslinking agent.

3. 3. The coated fiber according to claim 2, wherein the reaction product is formed by bonding the conjugated diene rubbers together via a crosslinking agent, and / or by bonding the conjugated diene rubber and the fiber via a crosslinking agent.

4. 4. The coated fiber according to claim 2, wherein the crosslinking agent is at least one selected from the group consisting of epoxy resins and isocyanate resins.

5. 3. The coated fiber according to claim 1, wherein the coating is applied in an amount of 0.01 to 10.0 parts by mass per 100 parts by mass of the fiber.

6. 3. The coated fiber according to claim 1, wherein the peak of the molecular weight distribution curve in GPC analysis of the coating is in the molecular weight range of 2,600 to 15,000.

7. The coated fiber according to claim 1 or 2, wherein the conjugated diene rubber is liquid.

8. 3. The coated fiber according to claim 1, wherein the conjugated diene rubber has monomer units derived from at least one selected from the group consisting of butadiene, isoprene, chloroprene, acrylonitrile, and farnesene.

9. The coated fiber according to claim 1 or 2, wherein the adhesive composition further comprises an oil having a vapor pressure of 10 Pa or less at 20°C.

10. 3. The coated fiber according to claim 1, 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.

11. The coated fiber according to claim 1 or 2, obtained by applying the water-based adhesive containing the conjugated diene rubber to the fiber and then heating it.

12. A molded article using the coated fiber according to claim 1 or 2.