Reinforcing fiber and molded article using the same

Abstract

Provided are: reinforcing fibers exhibiting excellent adhesiveness to rubber without the need to use resorcinol, formaldehyde or an epoxy compound; and a molded body that uses the same.　The reinforcing fibers are characterized: by comprising fibers, a surface-modifying layer for coating at least a portion of the surface of the fibers, and an adhesive layer that contains a conjugated diene rubber and covers at least a portion of the surface-modifying layer; and in that the surface-modifying layer has a weight-average molecular weight (Mw) of 300 or greater and contains a polyamine compound that has one or more functional groups selected from imino groups and primary to tertiary amine groups.

Description

Technical Field

[0001] The present invention relates to a reinforcing fiber having excellent adhesiveness to rubber and a molded body using the same.

Background Art

[0002] Synthetic organic fibers such as nylon 66, nylon 6, polyethylene terephthalate (PET), vinylon, and rayon are inexpensive, have high strength, are excellent in heat resistance and durability, and are lightweight. Therefore, they are used as reinforcing fibers for automobile tires and oil brake hoses. In these products, in order to fully exhibit the excellent physical properties (for example, high strength and high elastic modulus) of rubber, it is necessary to firmly bond the fiber and the rubber. Conventionally, as such an adhesion method, a method using an adhesive called RFL mainly composed of resorcinol formaldehyde resin and rubber latex is widely known in Patent Document 1. Further, in Patent Document 2, a device for retaining strength and improving fatigue resistance by impregnating RFL to the inside has been devised.

[0003] However, since formaldehyde is suspected of being carcinogenic and resorcinol is suspected of being an environmental hormone, development of alternative materials that do not use these raw materials is desired. For example, Patent Document 3 proposes a technique related to an adhesive containing an adhesive compound having an unsaturated carbon bond and an epoxy group that reacts with a vulcanizing agent used for vulcanization of rubber. Further, Patent Document 4 proposes a technique in which an active functional group layer is provided by applying a blocked isocyanate compound and an epoxy compound in the first stage, and an adhesive component mainly composed of latex and a low molecular weight conjugated diene rubber is used in the second stage. Furthermore, Patent Document 5 proposes a technique that does not use RFL by applying a blocked isocyanate compound, an epoxy compound, an amine-based curing agent, and VP latex.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] The method described in Patent Document 3 has a problem that its adhesiveness is inferior to that of the conventional method using RFL and it lacks practicality. In addition, the treatment described in Patent Document 4 requires a step of providing an intermediate layer called a rubber drawing layer and needs to perform heat treatment at high temperature in two stages. Therefore, it requires a great deal of energy for the treatment, and there is a concern about thermal deterioration of the fiber and the reinforcing performance may decrease. Note that Patent Document 4 only describes a technique using an adhesive component mainly composed of latex, and there is no description regarding the use of an adhesive component mainly composed of a conjugated diene rubber. In addition, the epoxy compound used in Patent Documents 3 to 5 has a problem that it is not preferable in terms of the working environment because it may cause factors such as mutagenicity and skin sensitization.

[0006] The present invention has been made in view of the above-mentioned conventional problems, and provides a reinforcing fiber having excellent adhesiveness to rubber and a molded body using the same without using resorcinol, formaldehyde, and an epoxy compound.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that by providing a surface-modified layer on at least a part of the surface of the fiber and incorporating a polyamine compound having a specific weight-average molecular weight in the surface-modified layer, the adhesiveness between the fiber and the rubber can be improved without using resorcinol, formaldehyde, and an epoxy compound, and thus completed the present invention.

[0008] That is, the present invention relates to the following [1] to [9]. [1] A reinforcing fiber having a fiber, a surface-modified layer covering at least a part of the surface of the fiber, and an adhesive layer containing a conjugated diene rubber covering at least a part of the surface-modified layer, wherein the surface-modified layer has at least one functional group selected from primary, secondary, and tertiary amino groups and imino groups, and contains a polyamine compound having a weight-average molecular weight (Mw) of 300 or more. [2] The reinforcing fiber according to [1] above, wherein the fiber is at least one fiber selected from polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and regenerated cellulose fibers. [3] The reinforcing fiber according to [1] or [2] above, wherein the amount of the surface-modified layer is 0.01 to 5.00 parts by mass with respect to 100 parts by mass of the fiber used as a raw material. [4] The reinforcing fiber according to any one of [1] to [3] above, wherein the number-average molecular weight (Mn) of the conjugated diene rubber is more than 2,000 and 120,000 or less.

[0009] [5] The reinforcing fiber according to any one of [1] to [4] above, wherein the conjugated diene rubber has a monomer unit derived from at least one selected from butadiene, isoprene, and farnesene in the molecule. [6] The conjugated diene rubber is a modified conjugated diene rubber having a hydrogen-bonding functional group in a part of the conjugated diene rubber, and the hydrogen-bonding functional group is selected from a hydroxy group, an epoxy group, an aldehyde group, an acetalized product of an aldehyde group, a carbonyl group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a silanol group, an esterified product of a silanol group, an amino group, an imidazole group, and a mercapto group, and is one or more selected therefrom. The reinforcing fiber according to any one of [1] to [5] above. [7] A molded article using the reinforcing fiber according to any one of [1] to [6] above. [8] The molded article according to [7] above, further having a rubber layer. [9] The molded article according to [7] or [8] above, wherein the molded article is a tire, a belt or a hose. [Advantages of the Invention]

[0010] The present invention can provide a reinforcing fiber having excellent adhesiveness to rubber and a molded article using the same without using resorcinol, formaldehyde and an epoxy compound. [Embodiments for Carrying Out the Invention]

[0011] [Reinforcing Fiber] The reinforcing fiber of the present invention is a reinforcing fiber having a fiber, a surface modification layer covering at least a part of the surface of the fiber, and an adhesive layer containing a conjugated diene rubber covering at least a part of the surface modification layer, and the surface modification layer has one or more functional groups selected from primary to tertiary amino groups and imino groups, and is characterized by containing a polyamine compound having a weight average molecular weight (Mw) of 300 or more. According to the present invention, since a surface modification layer containing a specific polyamine compound is provided on at least a part of the fiber surface, strong affinities are exhibited between the conjugated diene rubber, the substituent of the polyamine compound, and the fiber, and as a result, the adhesiveness between the fiber and the rubber is improved. In the present invention, the "surface modification layer covering at least a part of the surface of the fiber" may be a mode in which the surface modification layer exists as a film or a layer on at least a part of the surface of the fiber, or a component corresponding to the surface modification layer may be included in the raw material of the fiber, and a mode in which the component of the surface modification layer exists on a part of the surface of the fiber itself may also be acceptable. In the present invention, the "adhesive layer covering at least a part of the surface modification layer" may be such that the entire surface modification layer is covered with the adhesive layer, but it is sufficient that at least a part is covered with the adhesive layer. For example, it may be a mode in which an adhesive component exists as a film or a layer.

[0012] The adhesive layer in the present invention can obtain reinforcing fibers that are excellent in adhesiveness to rubber even without containing formaldehyde harmful to the human body and resins made from formaldehyde as a raw material. In the present invention, when the adhesive layer contains a resin made from formaldehyde as a raw material, examples of such resins include resorcinol / formaldehyde resin, phenol / formaldehyde resin, melamine / formaldehyde resin, and their derivatives. In the adhesive layer, when the formaldehyde component is contained, its content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and particularly preferably substantially not contained, based on 100 parts by mass of the conjugated diene rubber. The content of formaldehyde can be measured by using HPLC or the like after extracting the adhesive layer from the reinforcing fiber with a solvent such as toluene.

[0013] <Surface modification layer> The surface modification layer in the present invention is not particularly limited as long as it contains a polyamine compound having at least one functional group selected from primary to tertiary amino groups and imino groups and having a weight average molecular weight (Mw) of 300 or more. In the present invention, the "polyamine compound" refers to an aliphatic compound containing two or more amino groups in one molecule. Examples of the primary to tertiary amino groups include substituents represented by the following general formulas (I) to (III). -R 1 -NH2 (I) -R 1 -NR 2 H (II) -R 1 -NR 2 R 3 (III) (R 1 is a linear or branched alkylene chain having 1 to 20 carbon atoms which may have a substituent. Further, R 2 and R 3 are each independently a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent.) Among these amino groups, from the viewpoint of improving adhesiveness, the primary amino group represented by the general formula (I) or the secondary amino group represented by the general formula (II) is preferable. Further, the imino group is not particularly limited as long as it is a group having a carbon-nitrogen double bond, and examples thereof include an ethylideneamino group, a 1-methylpropylideneamino group, a 1,3-dimethylbutylideneamino group, a 1-methylethylideneamino group, a 4-N,N-dimethylaminobenzylideneamino group, and a cyclohexylideneamino group.

[0014] The weight average molecular weight of the polyamine compound in the present invention is 300 or more. When the weight average molecular weight is less than 300, the affinity with the adhesive layer containing the conjugated diene rubber is not exhibited, and the adhesive strength cannot be improved. From the viewpoint of improving adhesiveness, the weight average molecular weight of the polyamine compound may be 500 or more, 800 or more, 1,000 or more, or 1,500 or more. In addition, considering the deterioration of production efficiency due to the decrease in handleability, the upper limit value of the weight average molecular weight of the polyamine compound is generally 1,000,000 or less, and may be 800,000 or less. The weight average molecular weight of the polyamine compound is the weight average molecular weight in terms of polystyrene determined from the measurement by gel permeation chromatography (GPC), and specifically, it can be measured by the method described in the examples.

[0015] From the perspective of improving the adhesiveness with rubber, it is preferable that the surface modification layer covers the entire surface of the fiber. Substantially, it suffices to cover at least a part of the surface of the fiber. The specific amount of the surface modification layer covering the surface of the fiber is preferably 0.01 to 5.00 parts by mass, more preferably 0.05 to 3.00 parts by mass, still more preferably 0.10 to 2.00 parts by mass, and even more preferably 0.20 to 1.00 parts by mass with respect to 100 parts by mass of the fiber used as a raw material.

[0016] <Fiber> There is no particular limitation on the fiber used for the surface-modified fiber of the present invention, and hydrophilic fibers or hydrophobic fibers can be used. In the present invention, the "fiber" includes not only short fibers and long fibers but also forms such as non-woven fabrics, woven fabrics, knitted fabrics, felts, and sponges.

[0017] Examples of hydrophilic synthetic fibers include synthetic fibers composed of a thermoplastic resin having a hydrophilic functional group such as a hydroxy group, a carboxy group, a sulfonic acid group, and an amino group, and / or a hydrophilic bond such as an amide bond. Specific examples of such thermoplastic resins include polyvinyl alcohol-based resins, polyamide-based resins [aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 9C (polyamide composed of nonanediamine and cyclohexanedicarboxylic acid), etc.; semi-aromatic polyamides synthesized from an aromatic dicarboxylic acid and an aliphatic diamine such as polyamide 9T (polyamide composed of nonanediamine and terephthalic acid); wholly aromatic polyamides synthesized from an aromatic dicarboxylic acid and an aromatic diamine such as polyparaphenylene terephthalamide, etc.], polyacrylamide-based resins, and the like. Among these, polyvinyl alcohol-based resins and polyamide-based resins are preferable. The hydrophilic synthetic fibers may be used alone or in combination of two or more. Further, these hydrophilic synthetic fibers may be further subjected to a hydrophilization treatment described later in order to further enhance the hydrophilicity.

[0018] Examples of hydrophilic natural fibers include natural cellulose fibers such as wood pulp like kraft pulp, cotton pulp, and non-wood pulp like 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, one type at a time, or in combination of two or more types. Further, these hydrophilic natural fibers and regenerated fibers may be further subjected to a hydrophilization treatment described later to enhance the hydrophilicity.

[0019] The hydrophilic fiber only needs to have hydrophilicity at least on the surface. For example, it may be a fiber obtained by subjecting the surface of a hydrophobic fiber to a hydrophilization treatment, or a core-sheath type composite fiber having a hydrophobic resin as the core and a hydrophilic resin as the sheath. For examples of the hydrophilic resin constituting the sheath part, the description of hydrophilic synthetic fibers is cited. Examples of hydrophobic fibers made of a hydrophobic resin include the hydrophobic fibers described later.

[0020] The hydrophilization treatment is not particularly limited as long as it is a treatment for imparting a hydrophilic functional group to the fiber surface chemically or physically. For example, a method of modifying a hydrophobic fiber made of a hydrophobic resin described later with a compound or its derivative 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, and a urethane group, or a method of modifying the surface by electron beam irradiation can be used.

[0021] In the present invention, hydrophobic fibers that could not be firmly adhered to rubber in the prior art can also be used. Since hydrophobic fibers generally do not have polar functional groups on the fiber surface, they have poor affinity with the adhesive component described later and could not be firmly adhered to rubber. However, by providing a surface modification layer on the fiber surface as in the present invention, even hydrophobic fibers can be firmly adhered to rubber.

[0022] Examples of the hydrophobic fibers that can be used in the present invention 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 because they are excellent in terms of manufacturing cost, strength, heat resistance, durability, etc.

[0023] In the present invention, among the above fibers, synthetic fibers and recycled fibers are preferred, and one or more fibers selected from polyamide fibers, polyvinyl alcohol fibers, polyester fibers, and recycled cellulose fibers are particularly preferred. In the present invention, the fibers may be used alone or in combination of two or more.

[0024] <Method for producing a fiber having a surface-modified layer (surface-modified fiber)> The method for producing a fiber having a surface-modified layer on the surface is not particularly limited, but it can be produced by preparing a solution of the polyamine compound in water or an organic solvent, attaching this solution to the fiber, and then drying it by heat treatment or the like. The method for attaching the solution of the compound constituting the surface-modified layer to the fiber is not particularly limited, and it is preferably carried out by one or more selected from, for example, dipping, roll coater, oiling roller, oiling guide, nozzle (spray) coating, and brush coating.

[0025] As the heat treatment for drying the solution, it is preferably carried out at a treatment temperature of 100 to 250 °C for 0.1 second to 2 minutes. The heat treatment may be carried out only once at a specific temperature, or may be carried out two or more times by changing the treatment temperature and treatment time.

[0026] The surface-modified layer may contain other components in addition to the above. Examples of other components include crosslinking agents, acids, bases, inorganic salts, organic salts, pigments, dyes, antioxidants, polymerization initiators, plasticizers, etc. When the surface-modified layer contains the other component, the content of the other component in the surface-modified layer is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less from the viewpoint of improving the adhesion to the rubber.

[0027] <Adhesive layer> The adhesive layer in the reinforcing fiber of the present invention is not particularly limited as long as it contains a conjugated diene rubber. For example, it can be formed by attaching an adhesive component composed of an emulsion in which a conjugated diene rubber is dispersed in water to the surface-modified fiber. Hereinafter, the embodiments of the adhesive layer will be specifically described.

[0028] 〔Conjugated diene rubber〕 The conjugated diene rubber used in the present invention contains at least a monomer unit derived from a conjugated diene in the molecule (hereinafter, also referred to as "conjugated diene unit"). For example, it is preferable that the monomer unit derived from a conjugated diene is contained in 50 mol% or more of 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, β-farnesene (hereinafter, also referred to as "farnesene"), myrcene, chloroprene, and the like. 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 more preferably has a monomer unit derived from one or more selected from butadiene, isoprene, and farnesene.

[0029] The conjugated diene rubber used in the present invention may contain a unit derived from another monomer other than the conjugated diene monomer as long as it does not inhibit adhesion. Examples of the other monomer include copolymerizable ethylenically unsaturated monomers and aromatic vinyl compounds. Examples of the ethylenically unsaturated monomer include olefins such as ethylene, 1-butene, and isobutylene. Examples of the aromatic vinyl compound 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 monomer units derived from monomers other than the conjugated diene monomer, the content thereof is preferably 30 mol% or less, more preferably 10 mol% or less, and still more preferably 5 mol% or less.

[0030] The conjugated diene rubber used in the present invention is preferably a modified conjugated diene rubber having a hydrogen-bonding functional group in a part of the conjugated diene rubber, more preferably a modified conjugated diene rubber containing conjugated diene units in at least a part of the polymer chains and having a hydrogen-bonding functional group in the side chain or terminal of the polymer chains. When the modified conjugated diene rubber is used as the conjugated diene rubber, the modified conjugated diene rubber can interact with the rubber and the surface-modified fiber which are the adherends, thereby adhering 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, so that the adhesiveness is further improved. In addition, it is considered that the adhesiveness is improved by the hydrogen-bonding functional group contained in the modified conjugated diene rubber forming a hydrogen bond with the surface-modified layer of the surface-modified fiber.

[0031] In the present specification, the "hydrogen bond" means a bonding interaction formed between a hydrogen atom (donor) that is bonded to an atom with a high electronegativity (O, N, S, etc.) and is electrically polarized positively, and an electrically negative atom with a lone pair of electrons (acceptor).

[0032] In the present invention, the "hydrogen-bonding functional group" is a functional group that can function as a donor and an acceptor in the above-mentioned hydrogen bond. Specifically, a hydroxy group, an epoxy 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 can be mentioned. As a derivative of the aldehyde group, its acetalized product can be mentioned. As a derivative of the carboxy group, its salt, its esterified product, its amidated product, and its acid anhydride can be mentioned. As a derivative of the silanol group, its esterified product can be mentioned. Further, as the carboxy group, a group derived from a monocarboxylic acid and a group derived from a dicarboxylic acid can be mentioned. Among these, one or more selected from a hydroxy group, an epoxy group, an aldehyde group, an acetalized product of an aldehyde group, a carbonyl group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a silanol group, an esterified product of a silanol group, an amino group, an imidazole group, and a mercapto group are preferable. In the present invention, when the conjugated diene rubber has an epoxy group, the weight-average molecular weight per epoxy group is 1,000 or more. On the other hand, the epoxy compound used in the invention described in the above-mentioned prior art document has a molecular weight per epoxy group of less than 1,000, and the two differ in terms of the molecular weight per epoxy group. Among these hydrogen-bonding functional groups, from the viewpoints of improving adhesiveness and ease of producing the 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 preferable, 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 preferable, and an esterified product of maleic anhydride and a functional group derived from maleic anhydride are still more preferable.

[0033] From the viewpoint of obtaining a reinforcing fiber excellent in rubber adhesiveness, the number of hydrogen-bonding functional groups in the modified conjugated diene rubber is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more on average per molecule. Further, from the viewpoint of controlling the viscosity of the modified conjugated diene rubber within an appropriate range and improving handleability, the number of the hydrogen-bonding functional groups is preferably 80 or less, more preferably 40 or less, still more preferably 25 or less, and even more preferably 15 or less on average per molecule.

[0034] The average number of hydrogen-bonding functional groups per molecule of the modified conjugated diene rubber is calculated based on the following formula from the equivalent weight (g / eq) of the hydrogen-bonding functional group of the modified conjugated diene rubber and the number average molecular weight Mn in terms of styrene. The equivalent weight of the hydrogen-bonding functional group of the modified conjugated diene rubber means the mass of the conjugated diene bonded to each hydrogen-bonding functional group and other monomers contained as necessary other than the conjugated diene. Average number of hydrogen-bonding functional groups per molecule = [(number average molecular weight (Mn)) / (molecular weight of styrene unit) × (average molecular weight of conjugated diene and other monomer units contained as necessary other than the conjugated diene)] / (equivalent weight of hydrogen-bonding functional group) Note that the method for calculating the equivalent weight of the hydrogen-bonding functional group can be appropriately selected according to the type of the hydrogen-bonding functional group.

[0035] Examples of methods for obtaining a modified conjugated diene rubber include a method of obtaining by adding a modifying compound to a polymerized product of a conjugated diene monomer (hereinafter also referred to as "production method (1)"), a method of obtaining by oxidizing a conjugated diene polymer (hereinafter also referred to as "production method (2)"), a method of obtaining by copolymerizing a conjugated diene monomer and 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 a polymerization active terminal to a polymerized product of an unmodified conjugated diene monomer having a polymerization active terminal before adding a polymerization terminator (hereinafter also referred to as "production method (4)"). Among them, from the viewpoint of productivity, it is preferably produced by production method (1) or (2) or (3), more preferably produced by production method (1) or (3), and still more preferably produced by production method (1).

[0036] 〔Production method (1) of modified conjugated diene rubber〕 Production method (1) is a method of adding a modifying compound to a polymerized product of a conjugated diene monomer, that is, an unmodified conjugated diene rubber (hereinafter also referred to as "unmodified conjugated diene rubber"). The unmodified conjugated diene rubber can be obtained by polymerizing a conjugated diene and, if necessary, other monomers other than the conjugated diene by, for example, an emulsion polymerization method or a solution polymerization method.

[0037] As the solution polymerization method, a known method or a method equivalent to a known method can be applied. For example, in a solvent, using a Ziegler catalyst, a metallocene catalyst, an anion-polymerizable active metal or an active metal compound, and polymerizing a monomer containing a predetermined amount of conjugated diene in the presence of a polar compound if necessary. 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.

[0038] Examples of the anion-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 anion-polymerizable active metals, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. As the anion-polymerizable active metal compound, an organic alkali metal compound is preferred. Examples of the organic alkali metal compound include organic monolithium compounds such as methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; polyfunctional organic lithium compounds such as dilithiomethane, dilithionaphthalene, 1,4-dithiobutane, 1,4-dithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; and sodium naphthalene, potassium naphthalene, etc. Among these organic alkali metal compounds, organic lithium compounds are preferred, and organic monolithium compounds are more preferred.

[0039] The amount of the organic alkali metal compound used can be appropriately set according to the melt viscosity, molecular weight, etc. of the target unmodified conjugated diene rubber and modified conjugated diene rubber, but it is usually used in an amount of 0.01 to 3 parts by mass based on 100 parts by mass of all monomers containing conjugated diene. The organic alkali metal compound can also be reacted with a secondary amine such as dibutylamine, dihexylamine, or dibenzylamine and used as an organic alkali metal amide.

[0040] Polar compounds are usually used in anionic polymerization 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, 2,2 - bis(2 - tetrahydrofuryl)propane; tertiary amines such as tetramethylethylenediamine and trimethylamine; alkali metal alkoxides, phosphine compounds, and the like. Polar compounds are usually used in an amount of 0.01 to 1000 moles relative to the organic alkali metal compound.

[0041] The temperature of solution polymerization is usually in the range of - 80 to 150 °C, preferably in the range of 0 to 100 °C, more preferably in the range of 10 to 90 °C. The polymerization mode can be either batch or continuous. The polymerization reaction can be stopped by adding a polymerization terminator. Examples of polymerization terminators include alcohols such as methanol and isopropanol. The obtained polymerization reaction solution is poured into a poor solvent such as methanol to precipitate the polymerized product, or the polymerization reaction solution is washed with water, separated, and dried to isolate the unmodified conjugated diene rubber. Among the above methods, the solution polymerization method is preferred as a method for producing unmodified conjugated diene rubber.

[0042] As the emulsion polymerization method, a known or known - equivalent method can be applied. For example, a monomer containing a predetermined amount of conjugated diene is emulsified and dispersed in the presence of an emulsifier and emulsion - polymerized with a radical polymerization initiator. Examples of emulsifiers 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 usually used as the dispersion solvent, and it may contain water - soluble organic solvents such as methanol and ethanol as long as the stability during polymerization is not inhibited. Examples of radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate, organic peroxides, hydrogen peroxide, and the like. In order to adjust the molecular weight of the resulting unmodified conjugated diene rubber, a chain transfer agent may be used. Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; carbon tetrachloride, thioglycolic acid, diterpene, terpinolene, γ-terpinene, α-methylstyrene dimer, and the like.

[0043] The temperature of the emulsion polymerization can be appropriately set according to the type of radical polymerization initiator used, etc., but it is usually in the range of 0 to 100 °C, preferably in the range of 0 to 60 °C. The polymerization mode may be either continuous polymerization or batch polymerization.

[0044] The polymerization reaction can be stopped by adding a polymerization terminator. Examples of the polymerization terminator include amine compounds such as isopropyl hydroxylamine, diethyl hydroxylamine, and hydroxylamine; quinone compounds such as hydroquinone and benzoquinone; sodium nitrite, and the like.

[0045] After the polymerization reaction is stopped, an antioxidant may be added as necessary. After the polymerization reaction is stopped, unreacted monomers are removed from the obtained latex as necessary, and then salts such as sodium chloride, calcium chloride, and potassium chloride are used as a coagulant, and acids such as nitric acid and sulfuric acid are added as necessary to adjust the pH of the coagulation system to a predetermined value while coagulating the polymerized product, and then the polymerized product is recovered by separating the dispersion solvent. Then, after washing with water, dehydration, and drying, an unmodified conjugated diene rubber is obtained. In addition, at the time of coagulation, if necessary, the latex and an extended oil prepared in advance as an emulsion dispersion may be mixed and recovered as an oil-extended unmodified conjugated diene rubber.

[0046] (Modified compound used in production method (1)) The modified compound used in the production method (1) is not particularly limited, but from the viewpoint of improving the adhesion of the reinforcing fiber, those having a hydrogen-bonding functional group are preferable. Examples of the hydrogen-bonding functional group include the same ones as described above. Among them, from the viewpoint of the strength of the hydrogen bond, an amino group, an imidazole group, a urea group, a hydroxy group, an epoxy group, a mercapto group, a silanol group, an aldehyde group, a carboxy group and its derivatives are preferable. As the derivative of the carboxy group, its salt, its esterified product, its amidated product, or its acid anhydride is preferable. These modified compounds having a hydrogen-bonding functional group may be used alone or in combination of two or more.

[0047] Examples of the modified compound include unsaturated carboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid; unsaturated carboxylic acid anhydrides such as maleic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, and itaconic anhydride; unsaturated carboxylic acid esters such as maleic acid ester, fumaric acid ester, citraconic acid ester, and itaconic acid ester; unsaturated carboxylic acid amides such as maleic acid amide, fumaric acid amide, citraconic acid amide, and itaconic acid amide; unsaturated carboxylic acid imides such as maleic acid imide, fumaric acid imide, citraconic acid imide, and itaconic acid imide; silane compounds such as vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, mercaptomethylmethyldiethoxysilane, mercaptomethyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethylmethoxydimethylsilane, 2-mercaptoethylethoxydimethylsilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyldiethoxymethylsilane, 3-mercaptopropyldimethoxyethylsilane, 3-mercaptopropyldiethoxyethylsilane, 3-mercaptopropylmethoxydimethylsilane, and 3-mercaptopropylethoxydimethylsilane.

[0048] The amount of the modified compound used is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 50 parts by mass, and still more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the unmodified conjugated diene rubber. The reaction temperature is usually preferably in the range of 0 to 200°C, more preferably in the range of 50 to 200°C. In addition, after grafting the modified compound onto the unmodified conjugated diene rubber to introduce a hydrogen bonding functional group, a modified compound capable of reacting with the functional group may be further added to introduce another hydrogen bonding functional group into the polymer. Specifically, for example, a method of reacting a compound having a hydroxyl group such as 2-hydroxyethyl methacrylate or methanol, or a compound such as water with an unmodified conjugated diene rubber obtained by living anionic polymerization after grafting maleic anhydride can be mentioned.

[0049] The addition amount of the modified compound in the modified conjugated diene rubber is preferably 0.5 to 40 parts by mass, more preferably 1 to 30 parts by mass, and still more preferably 1.5 to 20 parts by mass with respect to 100 parts by mass of the unmodified conjugated diene rubber. Note that the amount of the modified compound added to the modified conjugated diene rubber can also be calculated based on the acid value of the modified compound, and can also be determined using various analytical instruments such as infrared spectroscopy and nuclear magnetic resonance spectroscopy.

[0050] The method for adding the modified compound to the unmodified conjugated diene rubber is not particularly limited. For example, a method of adding a radical generator as needed to a liquid unmodified conjugated diene rubber and one or more modified compounds selected from unsaturated carboxylic acids, unsaturated carboxylic acid derivatives, and silane compounds, and heating in the presence or absence of an organic solvent can be mentioned. There is no particular limitation on the radical generator to be used, and usually commercially available organic peroxides, azo compounds, hydrogen peroxide, etc. can be used. Examples of the organic solvent used in the above 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.

[0051] Furthermore, when performing the reaction of adding the modified compound by the above method, an antioxidant may be added from the viewpoint of suppressing side reactions. Examples of the antioxidant include phenolic antioxidants such as 2,6-di-butyl-4-methylphenol (BHT), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol) (AO-40), 3,9-bis[1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (AO-80), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganox1520L), 2,4-bis[(dodecylthio)methyl]-6-methylphenol (Irganox1726), 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]4,6-di-pentylphenyl acrylate (SumilizerGM), hydroquinone, p-methoxyphenol; phosphite antioxidants such as tris(2,4-di-t-butylphenyl) phosphite (Irganox168); amine antioxidants such as N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (No Crack 6C), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (LA-77Y), N,N-dioctadecylhydroxylamine (Irgastab FS042), bis(4-t-octylphenyl)amine (Irganox5057); sulfur antioxidants such as dioctadecyl 3,3'-dithiobispropionate, didodecyl-3,3'-thiodipropionate (Irganox PS800), bis[3-(dodecylthio)propionic acid-2,2-bis[3-(dodecylthio)-1-oxopropyl)oxy]methyl]-1,3-propanediyl (Mumilizer TP-D); composite antioxidants of phenolic antioxidants and phosphite antioxidants such as 6-t-butyl-[3-(2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yloxy)propyl]-methylphenol (Sumilizer GP); and the like.The anti-aging agent may be used alone or in combination of two or more kinds. Among these, it is preferable to use 2,6-di-butyl-4-methylphenol, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (No Crack 6C), etc. in terms of effects and versatility. The addition amount of the anti-aging agent is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the unmodified conjugated diene rubber. When the addition amount of the anti-aging agent is within the above range, side reactions can be suppressed, and a modified conjugated diene rubber can be obtained with good yield.

[0052] 〔Physical properties of conjugated diene rubber〕 The weight average molecular weight (Mw) of the conjugated diene rubber is not particularly limited, but from the viewpoint of improving adhesiveness, it is preferably more than 2,000, more preferably 5,000 or more, still more preferably 10,000 or more, even more preferably 15,000 or more, even more preferably 20,000 or more, particularly preferably 25,000 or more, and from the viewpoint of handleability, it is preferably 120,000 or less, more preferably 100,000 or less, still more preferably 75,000 or less, even more preferably 55,000 or less.

[0053] The number average molecular weight (Mn) of the conjugated diene rubber is not particularly limited, but from the viewpoint of improving adhesiveness, it is preferably more than 2,000, more preferably 5,000 or more, still more preferably 10,000 or more, even more preferably 15,000 or more, even more preferably 20,000 or more, particularly preferably 25,000 or more, and from the viewpoint of handleability, it is preferably 120,000 or less, more preferably 75,000 or less, still more preferably 50,000 or less, even more preferably 47,000 or less. The Mw and Mn of the conjugated diene rubber are the weight-average molecular weight and number-average molecular weight in terms of polystyrene determined from the measurement by gel permeation chromatography (GPC), and specifically, they can be measured by the method described in the examples.

[0054] The molecular weight distribution (Mw / Mn) of the conjugated diene rubber is preferably from 1.00 to 5.00, more preferably from 1.00 to 3.00, still more preferably from 1.00 to 2.00, even more preferably from 1.00 to 1.50, and particularly preferably from 1.00 to 1.30. When Mw / Mn is within the above range, the variation in the viscosity of the conjugated diene rubber is small and it is easy to handle. The molecular weight distribution (Mw / Mn) means the ratio of the weight-average molecular weight (Mw) / number-average molecular weight (Mn) in terms of standard polystyrene determined by GPC measurement.

[0055] Also, from the viewpoint of the adhesiveness between the conjugated diene rubber and the fiber, the conjugated diene rubber is preferably in a liquid state. In this specification, "liquid state" 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 the adhesiveness, the melt viscosity is preferably 0.1 Pa·s or more, more preferably 1 Pa·s or more, still more preferably 10 Pa·s or more, even more preferably 30 Pa·s or more, and even more preferably 50 Pa·s or more. From the viewpoint of handleability, it is preferably 2,500 Pa·s or less, and more preferably 2,100 Pa·s or less. When the melt viscosity is within the above range, the adhesiveness of the conjugated diene rubber can be improved while the handleability can be made good. The melt viscosity of the conjugated diene rubber means the viscosity measured at 38 °C using a Brookfield viscometer (type B viscometer).

[0056] The glass transition temperature (Tg) of the conjugated diene rubber can vary depending on the vinyl content of the conjugated diene unit, 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 -10 °C. When the Tg is within the above range, the increase in viscosity can be suppressed and handling becomes easier.

[0057] 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. When the vinyl content is within the above range, the adhesiveness is improved. In this specification, the "vinyl content" means the total mol% of conjugated diene units bonded by 1,2-bond or 3,4-bond (conjugated diene units bonded other than 1,4-bond) in a total of 100 mol% of conjugated diene units contained in the modified liquid diene rubber. The vinyl content is 1 It can be calculated from the integral value ratio of the signals derived from the conjugated diene units bonded by 1,2-bond or 3,4-bond and the signals derived from the conjugated diene units bonded by 1,4-bond using 1H-NMR.

[0058] In the present invention, it is preferable to form an adhesive layer by attaching an adhesive component composed of an emulsion in which the conjugated diene rubber is dispersed in water to the surface-modified fiber. When the conjugated diene rubber is dispersed in water and used as an oil-in-water emulsion, it is preferable to prepare an emulsion (latex) of the adhesive component in advance by a mechanical method or a chemical method and use it at a predetermined concentration by dilution or the like. Examples of the mechanical method include methods using a homogenizer, a homomixer, a disperser mixer, a colloid mill, a pipeline mixer, a high-pressure homogenizer, an ultrasonic emulsifier, etc., and these can be used alone or in combination. As chemical methods, various methods such as the reverse emulsification method, D-phase emulsification method, HLB temperature emulsification method, gel emulsification method, and liquid crystal emulsification method can be mentioned. From the viewpoint of easily obtaining an emulsion with a fine particle size, the reverse emulsification method is preferred. Further, in order to obtain an emulsion with a fine particle size, it may be preferable to carry out the operation while heating at an appropriate temperature (for example, 30 to 80 ° C) for the purpose of lowering the viscosity of the modified conjugated diene rubber.

[0059] Examples of the emulsifier include fatty acid soaps such as potassium or sodium salts of oleic acid, lauric acid, myristic acid, palmitic acid, stearic acid, etc., resin soaps such as potassium or sodium salts of rosin, disproportionated rosin, etc., sulfonic acid soaps such as sodium or potassium salts of alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, etc., sulfate esters such as sodium salts of oleyl sulfate ester, lauryl sulfate ester, polyoxyethylene alkyl sulfate ester, etc., phosphate soaps such as hexadecyl phosphate, polyoxyethylene lauryl ether phosphate, polyoxyethylene tridecyl ether phosphate, polyoxyethylene nonylphenyl phosphate, etc., anionic soaps, nonionic soaps such as polyoxyethylene nonylphenyl ether, polyethylene glycol laurate, polyethylene glycol oleate, etc., aliphatic amine hydrochlorides such as dodecylamine hydrochloride, and cationic soaps such as alkylpyridinium salts such as octyltrimethylammonium chloride, dioctyldimethylammonium chloride, benzyldimethyloctylammonium salt, dodecylpyridinium chloride. These may be used alone or in combination.

[0060] The amount of the emulsifier used is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the conjugated diene rubber. When the amount of the emulsifier used is below the above upper limit, an emulsion can be stably produced while suppressing the production cost. Further, when the amount of the emulsifier used is above the above lower limit, an increase in the emulsion particle size can be suppressed, and the occurrence of creaming and separation phenomena can be suppressed. For the purpose of enhancing the stability of the emulsion, alkaline substances such as sodium hydroxide, potassium hydroxide, and amines can be added as necessary to adjust the pH for use.

[0061] When the adhesive component is an emulsion, the content of the conjugated diene rubber in the adhesive component, from the viewpoint of improving the adhesive force with rubber, is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 80% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less, and even more preferably 40% by mass or less. When the content of the conjugated diene rubber in the adhesive component is within the above range, while obtaining sufficient adhesive force, it is possible to prevent the viscosity of the adhesive component from becoming extremely high.

[0062] In the present invention, the conjugated diene rubber may be used alone or in combination of two or more. Further, the adhesive component in the present invention may contain other components other than the conjugated diene rubber within a range that does not inhibit the adhesive force with rubber. Examples of the other components include other polymers (e.g., unmodified conjugated diene rubber), acids, alkalis, antioxidants, curing agents, dispersants, pigments, dyes, adhesion aids, carbon black, etc. When the adhesive component contains other components, the content is preferably 10,000 parts by mass or less, more preferably 1,000 parts by mass or less, still more preferably 100 parts by mass or less, and even more preferably 50 parts by mass or less with respect to 100 parts by mass of the conjugated diene rubber.

[0063] <Method for producing reinforcing fiber> There is no particular limitation on the method for producing the reinforcing fiber, and it can be produced by a method including a step of adhering the conjugated diene rubber to the fiber in a state of being dispersed in water. In the present invention, from the viewpoints of efficiently adhering the conjugated diene rubber to the surface-modified fiber (fiber having a surface-modified layer on the surface) and suppressing the contamination of the production equipment, a method including a step of adhering the conjugated diene rubber to the fiber in a state of being mixed with the oil may be adopted. As a more specific method for producing the reinforcing fibers of the present invention, the following methods may be mentioned.

[0064] 〔Method (I)〕 As Method (I), there is no particular limitation as long as it is a method of forming an adhesive layer composed of the above-mentioned adhesive component on the surface of the surface-modified fiber. However, from the viewpoint of improving the adhesiveness to rubber, a method including the following Step I-1 is preferable. Step I-1: A step of attaching the adhesive component to the surface of the surface-modified fiber

[0065] In Step I-1, there is no particular limitation on the method of attaching the adhesive component to the surface-modified fiber. For example, methods such as attaching the adhesive component as it is, or attaching it after adding a solvent to the adhesive component as necessary may be mentioned. As a method of attaching the adhesive component, it is preferably carried out by one or more selected from dipping, roll coater, oiling roller, oiling guide, nozzle (spray) coating, and brush coating.

[0066] From the viewpoint of improving the adhesiveness between the reinforcing fiber and the rubber, the amount of the adhesive component attached is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, still more preferably 1 part by mass or more, based on 100 parts by mass of the fiber used as a raw material. And from the viewpoint of the balance between the production cost and the effect, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 7 parts by mass or less.

[0067] In the present invention, after the adhesive component is attached to the surface-modified fiber, the reinforcing fiber of the present invention can be obtained by allowing it to conform at room temperature of about 20°C for about 3 to 10 days. However, in some cases, the following Step I-2 may be carried out. Step I-2: A step of heat-treating the surface-modified fiber to which the adhesive component obtained in Step I-1 is attached The heat treatment in Process I-2 is preferably carried out at a treatment temperature of 100 to 200 °C for a treatment time of 0.1 second to 2 minutes. Since the conjugated diene rubber contained in the adhesive component has reactive multiple bonds, the heat treatment in the presence of oxygen is preferably at 200 °C or lower, more preferably at 175 °C or lower. When the temperature of the heat treatment is within the above range, the amount of reactive multiple bonds in the conjugated diene rubber does not decrease, the adhesive strength can be improved, further deterioration of the fiber is suppressed, and the quality such as coloring becomes good.

[0068] The reinforcing fiber may contain other components in addition to the surface-modified fiber and the adhesive component. Examples of other components include crosslinking agents, acids, bases, inorganic salts, organic salts, pigments, dyes, antioxidants, polymerization initiators, plasticizers, and the like.

[0069] <Physical properties of the reinforcing fiber> The reinforcing fiber is preferably a multifilament having a single-filament fineness of 0.1 dtex or more and 30 dtex or less. The single-filament fineness may be less than 0.1 dtex, but 0.1 dtex or more is preferred because it is difficult to manufacture industrially. Further, when the single-filament fineness is 30 dtex or less, the surface area of the fiber as a reinforcing fiber increases, so the adhesiveness to rubber is improved. From this viewpoint, the reinforcing fiber of the present invention is more preferably a multifilament having a single-filament fineness of 0.3 dtex or more, still more preferably 0.5 dtex or more, even more preferably 1 dtex or more, and more preferably 20 dtex or less, still more preferably 15 dtex or less, even more preferably 10 dtex or less.

[0070] The rubber adhesiveness of the reinforcing fiber of the present invention is preferably 30 N / 3 pieces or more, more preferably 40 N / 3 pieces or more, still more preferably 50 N / 3 pieces or more, even more preferably 60 N / 3 pieces or more, and usually 200 N / 3 pieces or less. When the rubber adhesiveness of the reinforcing fiber is at the above lower limit value or more, a fabric, knitted fabric, and molded article excellent in reinforcing strength can be obtained. Note that the rubber adhesiveness of the reinforcing fiber can be measured by the method described in the examples.

[0071] The reinforcing fiber may have a fiber strength of 4 cN / dtex or more and 20 cN / dtex or less. For example, when used for a tire cord, PET or nylon fiber having a strength of 6 cN / dtex or more is preferable. Alternatively, when used for a hose, vinylon or PET having a strength of 6 cN / dtex or more is preferable.

[0072] The reinforcing fiber of the present invention can be used in any shape, but it is preferably used in the form of a fiber cord, a woven fabric, a knitted fabric, etc. that contains at least a part of the reinforcing fiber, and more preferably used as a woven fabric or a knitted fabric that contains at least a part of the reinforcing fiber. For example, it can be used as a knitted fabric that adheres to rubber as described later. It can also be used as a reinforcing fiber embedded in a resin, cement, etc.

[0073] [Molded article] The molded article of the present invention is not particularly limited as long as it uses the reinforcing fiber. Among them, since the reinforcing fiber has excellent adhesiveness with rubber, a molded article having the reinforcing fiber and a rubber layer (hereinafter, also referred to as a "rubber molded article") is particularly preferable. The reinforcing fiber used in the rubber molded article is preferably used as a woven fabric or a knitted fabric that contains at least a part of the reinforcing fiber from the viewpoint of maintaining the form of the rubber, and more preferably used as a laminate in which a reinforcing layer made of a woven fabric or a knitted fabric that contains at least a part of the reinforcing fiber and a rubber layer are laminated.

[0074] The rubber molded article can be used as a member of rubber products such as tires such as automobile tires, conveyor belts, timing belts, hoses, and vibration-proof rubbers. Among them, it is more preferably used as a tire, a belt, or a hose. As the automobile tire, it can be used for various members made of a composite material of a reinforcing fiber and a rubber component such as a belt, a carcass ply, a breaker, and a bead tape. The hose can be used for transporting various fluids in various applications. For example, it is suitable for use as a hose for transporting fluids in automobiles, and in particular, it is preferably used for a hose for liquid fuel in automobiles, a brake oil hose for automobiles, and a refrigerant hose for automobiles, and more preferably used for a brake oil hose for automobiles.

[0075] The rubber molded body is preferably formed using the reinforcing fiber and a rubber composition obtained by blending a compounding agent commonly used in the rubber industry with a rubber component. The rubber component is not particularly limited. For example, 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, CR (chloroprene rubber), etc. can be mentioned. Among these, it is more preferable to use NR, BR, or SBR. These rubber components may be used alone or in combination of two or more. In tire applications, those commonly used in the tire industry can be used. Among them, it is preferable to use natural rubber alone, or a combination of natural rubber and SBR, natural rubber and BR, or SBR and BR.

[0076] Examples of the natural rubber include TSR (Technically Specified Rubber) such as SMR (TSR produced in Malaysia), SIR (TSR produced in Indonesia), STR (TSR produced in Thailand), and natural rubbers commonly used in the tire industry such as RSS (Ribbed Smoked Sheet), high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, grafted natural rubber, and other modified natural rubbers.

[0077] As the SBR, a general one used in tire applications can be used. Specifically, those having a styrene content of 0.1 to 70% by mass are preferred, those having a styrene content of 5 to 50% by mass are more preferred, and those having a styrene content of 15 to 35% by mass are even more preferred. Also, those having a vinyl content of 0.1 to 60% by mass are preferred, and those having a vinyl content of 0.1 to 55% by mass are more preferred. The weight average molecular weight (Mw) of the SBR is preferably from 100,000 to 2,500,000, more preferably from 150,000 to 2,000,000, and even more preferably from 200,000 to 1,500,000. When within the above range, both processability and mechanical strength can be achieved. The weight average molecular weight of SBR is the weight average molecular weight in terms of polystyrene determined from measurements by gel permeation chromatography (GPC). As the SBR, a modified SBR in which a functional group is introduced into the SBR may be used as long as the effects of the present invention are not impaired. Examples of the functional group include an amino group, an alkoxysilyl group, a hydroxy group, an epoxy group, a carboxy group, and the like.

[0078] 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 balloon; and organic fillers such as resin particles, wood flour, and cork powder. The inclusion of such a filler in the rubber composition enables the improvement of physical properties such as mechanical strength, heat resistance, or weather resistance, the adjustment of hardness, and the increase in the amount of rubber. From the viewpoint of improving physical properties such as enhancing mechanical strength, carbon black and silica are preferred among the fillers.

[0079] Examples of the carbon black include furnace black, channel black, thermal black, acetylene black, and ketjen black. From the viewpoints of crosslinking speed and improvement of mechanical strength, furnace black is preferred among these carbon blacks. The average particle size of the carbon black is preferably 5 to 100 nm, more preferably 5 to 80 nm, and still more preferably 5 to 70 nm. The average particle size of the carbon black can be determined by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

[0080] Examples of the silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Among these silicas, 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 still more preferably 10 to 100 nm. The average particle size of the silica can be determined by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

[0081] In the rubber composition, the content of the filler relative to 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 still more preferably 25 to 110 parts by mass. When a filler other than silica and carbon black is used as the filler, the content is preferably 20 to 120 parts by mass, more preferably 20 to 90 parts by mass, and still more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the rubber component. These fillers may be used alone or in combination of two or more.

[0082] The rubber composition may further contain a crosslinking agent in order to crosslink the rubber component. Examples of the crosslinking agent include sulfur, sulfur compounds, oxygen, organic peroxides, phenolic resins, amino resins, quinones 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 perspective of the mechanical properties of the crosslinked product, the crosslinking agent is usually contained in an amount of 0.1 to 10 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.8 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0083] When the rubber composition contains sulfur, sulfur compounds, etc. as a crosslinking agent for crosslinking (vulcanizing) the rubber component, for example, it 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 vulcanization accelerator is usually contained in an amount of 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0084] When the rubber composition contains sulfur, sulfur compounds, etc. as a crosslinking agent for crosslinking (vulcanizing) the rubber component, for example, it 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 vulcanization aid is usually contained in an amount of 0.1 to 15 parts by mass, preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0085] When the rubber composition contains silica as a filler, it is preferably further contained with a silane coupling agent. Examples of the silane coupling agent include sulfide compounds, mercapto compounds, vinyl compounds, amino compounds, glycidoxy compounds, nitro compounds, chloro compounds and the like. 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 still more preferably 1 to 15 parts by mass with respect to 100 parts by mass of silica. When the content of the silane coupling agent is within the above range, the dispersibility, coupling effect, and reinforcing property are improved.

[0086] The rubber composition may contain, as a softening agent, a resin component such as silicone oil, aroma oil, TDAE (Treated Distilled Aromatic Extracts), MES (Mild Extracted Solvates), RAE (Residual Aromatic Extracts), paraffin oil, naphthene oil and the like, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, C9 resin, rosin resin, coumarone-indene resin, phenolic resin and the like for the purpose of improving processability, fluidity and the like within a range not inhibiting the effects of the present invention. When the rubber composition contains the process oil as a softening agent, its content is preferably less than 50 parts by mass with respect to 100 parts by mass of the rubber component.

[0087] 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, ultraviolet absorbers, mold release agents, foaming agents, antibacterial agents, fungicides, fragrances, etc., as long as the effects of the present invention are not inhibited. Examples of the antioxidant include hindered phenol compounds, phosphorus compounds, lactone compounds, hydroxyl compounds, etc. Examples of the anti-aging agent include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, phosphorus compounds, etc. These additives may be used alone or in combination of two or more.

[0088] As a method for manufacturing the rubber molded body, for example, the reinforcing fiber is embedded in the unvulcanized rubber composition, and the rubber composition is vulcanized to obtain a molded body in which the surface-modified fiber and the rubber component are adhered via the adhesive component.

[0089] Examples of the brake oil hose for automobiles include those having an inner rubber layer and an outer rubber layer, and having a reinforcing layer composed of one or two layers of the reinforcing fibers between the inner rubber layer and the outer rubber layer. Examples of the rubber component constituting the inner rubber layer and the outer rubber layer include those described above. Among them, examples of the rubber component constituting the inner rubber layer include EPDM, SBR, etc., and examples of the rubber component constituting the outer rubber layer include EPDM, CR, etc. The reinforcing layer can be formed by braiding the reinforcing fibers. As a method for manufacturing the brake oil hose, a reinforcing layer (first reinforcing layer) obtained by braiding the reinforcing fibers is formed on the outer surface of the inner rubber layer. When forming two layers of reinforcing layers, an intermediate rubber layer may be further formed on the outer surface of the first reinforcing layer, and a reinforcing layer (second reinforcing layer) obtained by braiding the reinforcing fibers may be formed on the outer surface of the intermediate rubber layer. Then, an outer rubber layer is formed on the outer surface of the reinforcing layer (first reinforcing layer or second reinforcing layer) and vulcanized to manufacture it. The vulcanization temperature can be appropriately selected according to the type of the constituent material of each layer of the brake oil hose, etc., but from the viewpoint of suppressing the deterioration of the rubber and the reinforcing fiber and improving the adhesive force between the rubber and the reinforcing fiber, it is preferably 200°C or lower.

Example

[0090] Hereinafter, the present invention will be described in more detail by way of examples, etc., but the present invention is not limited by such examples, etc. <Production of modified conjugated diene rubber> · Production of modified conjugated diene rubber having a monomer unit represented by the following formula (1a)

Chemical formula

[0091] Production Example 1: Production of modified conjugated diene rubber (A-1) A thoroughly dried 5 L autoclave was purged with nitrogen, charged with 1140 g of hexane and 20.9 g of n-butyllithium (17% by mass hexane solution), heated to 50°C, and then, while controlling the polymerization temperature to be 50°C under stirring conditions, 1390 g of butadiene was sequentially added and polymerized for 1 hour. Thereafter, methanol was added to stop the polymerization reaction, and a polymer solution was obtained. Water was added to the obtained polymer solution and stirred, and the polymer solution was washed with water. After confirming that the stirring was completed and the polymer solution phase and the water phase were separated, the water was separated. The polymer solution after the washing was vacuum dried at 70°C for 24 hours to obtain unmodified liquid polybutadiene (A'-1). Subsequently, 500 g of the obtained unmodified liquid polybutadiene (A'-1) was charged into a 1 L autoclave purged with nitrogen, 25 g of maleic anhydride and 0.5 g of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (trade name "No Crack 6C", manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) were added, and the reaction was carried out at 170°C for 24 hours to obtain maleic anhydride-modified liquid polybutadiene (A-1).

[0092] Production Example 2: Production of modified conjugated diene rubber (A-2) A 5 L autoclave that was thoroughly dried was purged with nitrogen, charged with 1260 g of hexane and 36.3 g of n-butyllithium (17% by mass hexane solution), heated to 50°C, and then, while controlling the polymerization temperature to 50°C under stirring conditions, 1260 g of butadiene was sequentially added and polymerized for 1 hour. Thereafter, methanol was added to terminate the polymerization reaction, and a polymer solution was obtained. Water was added to the obtained polymer solution and stirred to wash the polymer solution with water. After confirming that the stirring was completed and the polymer solution phase and the water phase were separated, the water was separated. The polymer solution after completion of washing was vacuum dried at 70°C for 24 hours to obtain 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, 25 g of maleic anhydride and 0.5 g of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (trade name "No Crack 6C", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added, and the reaction was carried out at 170°C for 24 hours to obtain maleic anhydride-modified liquid polybutadiene. To 525 g of the obtained maleic anhydride-modified liquid polybutadiene, 8.5 g of methanol was added and the reaction was carried out at 80°C for 6 hours to obtain maleic acid monomethyl-modified liquid polybutadiene (A-2).

[0093] Production Example 3: Production of modified conjugated diene rubber (A-3) To 525 g of the maleic anhydride-modified liquid polybutadiene (A-1) obtained in Production Example 1, 9.0 g of methanol was added and the reaction was carried out at 80°C for 6 hours to obtain maleic acid monomethyl-modified liquid polybutadiene (A-3).

[0094] The measurement methods and calculation methods for the physical properties of the polyamine compound and the modified conjugated diene rubber are as follows. The results are shown in Tables 1 and 2. <Measurement method for weight average molecular weight, number average molecular weight and molecular weight distribution> The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polyamine compound and the modified conjugated diene rubber were determined as standard polystyrene conversion values by GPC (gel permeation chromatography). The measuring apparatus and conditions are as follows. · Apparatus: GPC apparatus "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

[0095] <Method for measuring melt viscosity> The melt viscosity of the modified conjugated diene rubber at 38 °C was measured using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

[0096] <Method for measuring glass transition temperature> 10 mg of the modified conjugated diene rubber was placed in an aluminum pan, and a thermogram was measured by differential scanning calorimetry (DSC) under a heating rate condition of 10 °C / min. The value at the peak top of the DDSC was taken as the glass transition temperature.

[0097] <Method for measuring vinyl content> The vinyl content of the modified conjugated diene rubber was measured using a 1H-NMR (500 MHz) manufactured by JEOL Ltd. 1 at a concentration of sample / deuterated chloroform = 50 mg / 1 mL and an integration number of 1024 times. The vinyl content was calculated from the area ratio between the peak of the double bond derived from the vinylated diene compound and the peak of the double bond derived from the non-vinylated diene compound in the obtained spectrum.

[0098] <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 group 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 unit) × (Average molecular weight of conjugated diene and other monomer units contained as necessary other than conjugated diene)] / (Equivalent weight of hydrogen-bonding functional group) The method for calculating the equivalent weight of the hydrogen-bonding functional group can be appropriately selected according to the type of the hydrogen-bonding functional group.

[0099] The calculation of the average number of hydrogen-bonding functional groups per molecule of maleic anhydride-modified conjugated diene rubber and maleic acid monomethyl ester-modified conjugated diene rubber was performed by determining the acid value of maleic anhydride-modified conjugated diene rubber and maleic acid monomethyl ester-modified conjugated diene rubber and calculating the equivalent weight (g / eq) of the hydrogen-bonding functional group from the acid value. After the sample after the modification reaction was washed 4 times with methanol (5 mL per 1 g of the sample) to remove impurities such as antioxidants, the sample was dried under reduced pressure at 80 °C for 12 hours. After adding 180 mL of toluene and 20 mL of ethanol to 3 g of the sample after the modification reaction and dissolving it, neutralization titration was performed with an ethanol solution of 0.1 N potassium hydroxide, and the acid value was determined from the following formula. Acid value (mgKOH / g) = (A - B) × F × 5.611 / S A: Dropwise addition amount (mL) of the ethanol solution of 0.1 N potassium hydroxide required for neutralization B: Dropwise addition amount (mL) of the ethanol solution of 0.1 N potassium hydroxide in a blank not containing the sample F: Normality of the ethanol solution of 0.1 N potassium hydroxide S: Mass (g) of the weighed sample

[0100] From the acid value, the mass of the hydrogen-bonding functional groups contained per gram of maleic anhydride-modified conjugated diene rubber and monomethyl maleate-modified conjugated diene rubber was calculated according to the following formula, and further, the mass other than the functional groups (polymer main chain mass) contained per gram of maleic anhydride-modified conjugated diene rubber and monomethyl maleate-modified conjugated diene rubber was calculated. Then, the equivalent weight (g / eq) of the hydrogen-bonding functional groups was calculated from the following formula. [Mass of hydrogen-bonding functional groups per gram] = [Acid value] / [56.11] × [Molecular weight of hydrogen-bonding functional groups] / 1000 [Mass of polymer main chain per gram] = 1 - [Mass of hydrogen-bonding functional groups per gram] [Equivalent weight of hydrogen-bonding functional groups] = [Mass of polymer main chain per gram] / ([Mass of hydrogen-bonding functional groups per gram] / [Molecular weight of hydrogen-bonding functional groups])

[0101] [Table 1]

[0102] The compounds used for the surface modification layer and their properties are shown in Table 2.

[0103] [Table 2]

[0104] Note that the compounds in Table 2 are as follows. [B-1] Polyethyleneimine (SP-200 manufactured by Nippon Shokubai Co., Ltd.) [B-2] Polyallylamine (PAA-15 manufactured by Nitto Boseki Co., Ltd.) [B-3] Polyallylamine (PAA-01 manufactured by Nitto Boseki Co., Ltd.) [B-4] Polyethyleneimine (SP-006 manufactured by Nippon Shokubai Co., Ltd.) [B-5] Polyallylamine (PAS-21 manufactured by Nitto Boseki Co., Ltd.) [B-6] Polyethyleneimine (Lupasol series manufactured by BASF Japan Ltd.)

[0105] [X-1] Quaternary ammonium-containing acrylic polymer (Daisheng Fine Chemical Co., Ltd. 1WX-1020) [X-2] Ethylenediamine (manufactured by Fujifilm Wako Pure Chemical Corporation) [X-3] Triethylenetetramine (manufactured by Fujifilm Wako Pure Chemical Corporation) [X-4] Pentaethylenehexamine (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0106] [Preparation of conjugated diene rubber-containing emulsion constituting the adhesive layer] 18 g of a nonionic surfactant was added to 300 g of each modified conjugated diene rubber described in Table 1 and mixed uniformly. Then, 682 g of an aqueous sodium hydroxide solution was gradually added while continuing stirring to obtain an emulsion having a solid content of 30 parts by mass.

[0107] [Preparation of aqueous solution constituting the surface modification layer] An aqueous solution constituting the surface modification layer was prepared by mixing 5 g of the compound described in Table 2 and 955 g of water, respectively.

[0108] [Example 1] Two nylon fibers, which are polyamide fibers (total fineness 1400 dtex, single fiber fineness 6.86 dtex), were twisted at 470 twists / m in the Z direction and 470 twists / m in the S direction to produce a twisted fiber cord. The twisted fiber cord was immersed in an aqueous solution containing a surface modifier (B-1) and then squeezed with a roller. The obtained fiber cord was dried at 140°C for 60 seconds and further heat-treated at 210°C for 60 seconds to produce a surface-modified fiber. Next, after dipping into an emulsion containing a modified conjugated diene rubber (A-2), squeezing with a roller, drying at 140 °C for 60 seconds, and then winding up, reinforcing fibers were produced.

[0109] <Examples 2 to 7, 9 to 11 and Comparative Examples 1 to 5> Reinforcing fibers were produced in the same manner as in Example 1, except that the surface modification layer, the adhesive layer, and their adhesion amounts were changed as shown in Table 3.

[0110] <Example 8> Reinforcing fibers were produced in the same manner as in Example 1, except that the fiber was changed to vinylon fiber, which is a polyvinyl alcohol-based fiber (total fineness 1200 dtex, single fiber fineness 6.00 dtex).

[0111] <Reference Examples 1, 2> As Reference Example 1, two nylon 6 fibers, which are polyamide-based fibers (fineness 1400 dtex, single fiber fineness 6.86 dtex), and as Reference Example 2, two vinylon fibers, which are polyvinyl alcohol-based fibers (fineness 1200 dtex, single fiber fineness 6.00 dtex), were respectively twisted and combined to produce twisted fiber cords by applying 470 twists / m in the S direction and 470 twists / m in the Z direction. After dipping these into the RFL liquid described below, squeezing with a roller, drying at 140 °C for 60 seconds, and further heat-treating at 210 °C for 60 seconds, the reinforcing fibers of Reference Examples 1 and 2 were produced. The RFL liquid used was prepared by the following method.

[0112] 〔Adjustment of RFL liquid〕 Liquid A Water: 1727 parts by mass Resorcinol: 15 parts by mass Formaldehyde (effective content 37% by mass): 16 parts by mass Sodium hydroxide aqueous solution (effective content 10% by mass): 4 parts by mass The above Liquid A was aged at a temperature of 25 °C for 6 hours.

[0113] Liquid B SBR latex (effective content 40% by mass): 207 parts by mass Vinylpyridine-modified SBR latex (active ingredient: 40% by mass): 233 parts by mass After mixing the above Solution B and the aged Solution A, the mixture was aged at a temperature of 25°C for 16 hours to produce an RFL solution.

[0114] <Measurement of rubber adhesion strength> For the reinforcing fibers obtained in the examples, comparative examples, and reference examples, test specimens for evaluation were prepared by the following method. The force (N / 3 strands) required to peel the test specimens for evaluation from the rubber was measured and evaluated as the rubber adhesion strength. The results are shown in Table 3. The evaluation results of the rubber adhesion strength indicate that the greater the numerical value, the greater the adhesion strength between the reinforcing fiber and the rubber.

[0115] [Preparation of test specimens for evaluation] The reinforcing fibers prepared in the above-described examples, comparative examples, and reference examples were arranged in three strands at regular intervals in an NR / SBR unvulcanized rubber composition prepared by the following formulation. Then, a test specimen for evaluation was prepared by press vulcanization at 150°C and a pressure of 20 kg / cm 2 for 30 minutes under the conditions.

[0116] [Formulation composition of NR / SBR unvulcanized rubber] NR rubber: 70 parts by mass SBR rubber: 41.25 parts by mass Filler (carbon black): 45 parts by mass Vulcanizing agent (sulfur powder): 3.5 parts by mass Vulcanization aid (zinc oxide, stearic acid): 6 parts by mass Vulcanization accelerator (thiazole-based): 1 part by mass

[0117]

Table 3

[0118] As is clear from the results of the examples and comparative examples, according to the present invention, a reinforcing fiber excellent in adhesion to rubber can be obtained. In particular, according to the present invention, the fiber and the rubber can be firmly adhered without using resorcinol, formaldehyde and an epoxy compound.

Claims

1. A reinforcing fiber having a fiber, a surface modification layer covering at least a part of the surface of the fiber, and an adhesive layer containing a conjugated diene rubber covering at least a part of the surface modification layer, wherein the surface modification layer contains a polyamine compound having at least one functional group selected from primary to tertiary amino groups and imino groups and having a weight average molecular weight (Mw) of 300 or more, and the conjugated diene rubber is a modified conjugated diene rubber having a hydrogen-bonding functional group in a part of the conjugated diene rubber, and the hydrogen-bonding functional group is selected from a hydroxy group, an epoxy group, an aldehyde group, an acetalized product of an aldehyde group, a carbonyl group, a carboxy group, a salt of a carboxy group, an esterified product of a carboxy group, an acid anhydride of a carboxy group, a silanol group, an esterified product of a silanol group, an amino group, an imidazole group, and a mercapto group. The reinforcing fiber is characterized by being at least one selected from the group consisting of:

2. The reinforcing fiber according to claim 1, wherein the fiber is at least one fiber selected from a polyamide fiber, a polyvinyl alcohol fiber, a polyester fiber, and a regenerated cellulose fiber.

3. The reinforcing fiber according to claim 1 or 2, wherein the amount of the surface modification layer is 0.01 to 5.00 parts by mass with respect to 100 parts by mass of the fiber used as a raw material.

4. The reinforcing fiber according to any one of claims 1 to 3, wherein the number average molecular weight (Mn) of the conjugated diene rubber is more than 2,000 and 120,000 or less.

5. The reinforcing fiber according to any one of claims 1 to 4, wherein the conjugated diene rubber has a monomer unit derived from at least one selected from butadiene, isoprene, and farnesene in the molecule.

6. In the adhesive layer, the content of formaldehyde is 1 part by mass or less with respect to 100 parts by mass of the conjugated diene rubber. The reinforcing fiber according to any one of claims 1 to 5.

7. A molded article using the reinforcing fiber according to any one of claims 1 to 6.

8. The molded article according to claim 7, further having a rubber layer.

9. The molded article according to claim 7 or 8, wherein the molded article is a tire, a belt, or a hose.

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