Adhesive composition for organic fibers, and organic fiber materials, rubber articles, organic fiber-rubber composites, and tires using the same

Abstract

To provide an adhesive composition for organic fiber that can ensure desired adhesiveness without using resorcin and does not impair workability during use, and to provide an organic fiber material, a rubber article, an organic fiber-rubber composite and a tire using the same.SOLUTION: Provided are an adhesive composition for organic fiber that contains (A) a rubber latex having unsaturated diene and (B) acetoacetyl group-modified polyvinyl alcohol, and an organic fiber material, a rubber article, an organic fiber-rubber composite and a tire using the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition for organic fibers (hereinafter also simply referred to as "adhesive composition"), and to an organic fiber material, a rubber article, an organic fiber-rubber composite, and a tire using the same. [Background technology]

[0002] Conventionally, for the purpose of reinforcing rubber articles such as tires, organic fibers such as tire cords made of nylon fibers, polyester fibers, or the like have been bonded to rubber compositions such as rubber compositions for tires to form organic fiber-rubber composites. A commonly used method for the bonding is to coat the organic fibers with an adhesive composition, embed them in the rubber composition, and co-vulcanize them with the rubber composition.

[0003] In addition, in the step of coating the organic fibers with the adhesive composition, a solvent is generally used to adjust the viscosity of the adhesive composition, but since the solvent volatilizes in this step, it is preferable to use water, which has a low environmental impact, as the solvent. Furthermore, when coating the organic fibers with the adhesive composition by immersion, it is necessary to make the viscosity of the adhesive composition low enough to be able to apply it by immersion.

[0004] Generally, components contained in aqueous adhesive compositions that are water-based, i.e., capable of dissolving or dispersing in water, must have a polar molecular structure. However, polymeric materials such as rubber and organic fiber substrates, which serve as adherends, have low polarity, and adhesion becomes difficult when the polarity of the surface of the rubber or organic fiber substrate differs greatly from the polarity of the components contained in the adhesive composition. Therefore, in order to use the aqueous adhesive composition as an adhesive composition for rubber articles, the components contained in the aqueous adhesive composition must have polarity because they are aqueous. However, this polarity must be controlled so that a difference in polarity with the adherend does not result in a decrease in adhesion. Therefore, aqueous adhesive compositions that can satisfy these contradictory requirements are preferably used.

[0005] Here, with regard to the step of coating the organic fiber with the adhesive composition, an example of a step in which an organic fiber cord such as a tire cord is immersed in the adhesive composition will be described with reference to FIG.

[0006] An organic fiber cord 1 is unwound from a winding roll, transported by rolls, and placed in a dipping bath (dipping tank) 3 containing an adhesive composition 2, where it is immersed in the adhesive composition 2. The organic fiber cord 4 coated with the adhesive composition 2 is pulled out of the dipping bath 3, and excess adhesive composition 2 is removed by a squeezing roll 5. The organic fiber cord 4 coated with the adhesive composition 2 is then further transported by rolls, dried in a drying zone 6, stretched by applying tension in a hot zone 7 and subjected to thermal curing of the resin, and thermally cured in a normalization zone 8 while the tension is precisely adjusted to achieve the desired strength and elongation properties (normalization), air-cooled outside the zone, and then wound up on a take-up roll. In this way, the organic fiber is coated with the adhesive composition.

[0007] Conventionally, the adhesive composition used has been an RFL (resorcinol-formaldehyde-latex) adhesive composition obtained by aging a mixed liquid containing resorcinol, formaldehyde, and rubber latex, or an adhesive composition obtained by mixing this RFL adhesive composition with a specific adhesion promoter (see Patent Documents 1 to 4).

[0008] As is well known, in the rubber industry, an adhesive composition (Patent Document 1) consisting of a water-dispersible rubber latex component and an aqueous phenolic resin obtained by mixing and maturing water-soluble resorcinol and formaldehyde has been found to have the function of both bonding to the rubber substrate and bonding to the surface of a substrate with low polarity, such as organic fibers, and is therefore widely used worldwide. In bonding with the RFL adhesive composition, the rubber latex component bonds to the rubber substrate by co-vulcanization, while the phenolic resin component, which is a condensate of resorcinol and formaldehyde and has adhesive properties with organic fiber substrates, bonds to the substrate.

[0009] Here, the reason why resorcinol is preferably used is that it can provide a phenolic condensation resin, which is a resin type that has high adhesion to the substrate, and the polar functional group introduced into the phenol ring to achieve water solubility is a hydroxyl group, which has relatively low polarity and is not likely to cause steric hindrance, and therefore it can provide a resin component that has high adhesion to the organic fiber substrate.

[0010] The RFL adhesive composition is obtained by mixing and aging resorcinol, formaldehyde, and a rubber latex that uses rosin acid or the like as an emulsifier during polymerization in the presence of a basic composition. As a result, it is presumed that the water-dissolved resorcinol and formaldehyde undergo a resol-type condensation reaction in the presence of a base (see Patent Document 2), and that the rosin acid on the surface of the latex undergoes addition-condensation with the terminal methylol groups of a resol-type phenol-formaldehyde addition-condensate (see Non-Patent Document 1).

[0011] This aging process causes the latex to crosslink with the resol-type resorcinol-formaldehyde condensate via rosin acid or the like, strengthening the adhesion, and the latex forms an encapsulated protective colloid in combination with the aqueous resin. This suppresses the rubber-like tackiness of the latex when the adhesive composition is processed in equipment such as that shown in Figure 1, thereby reducing staining of the equipment caused by the adhesive composition sticking to it.

[0012] As the adhesion promoter added to the RFL adhesive composition, an aqueous adhesion promoter, i.e., an adhesion promoter that is soluble or dispersible in water, has been used to improve adhesion of the aqueous adhesive composition to the surface of a substrate with low polarity, such as an organic fiber cord material.

[0013] Examples of the water-dispersible adhesion promoters that have been used include (blocked) isocyanates such as methylene diphenyl diisocyanate having a particle size of 0.01 to 0.50 μm (see Patent Document 3), and water-dispersed particles of water-insoluble phenolic novolac resins such as cresol novolac polyfunctional epoxy resins (see Patent Document 4).

[0014] Furthermore, examples of the adhesion promoters containing water-soluble groups that have been used in combination with RFL adhesive compositions include sodium hydroxide solutions of novolac condensates obtained by novolac reaction between resorcinol and formaldehyde (see Patent Document 5), and phenolic resins that dissolve in water in the presence of a basic substance, such as ammonium solutions of novolac condensates of chlorophenols and formaldehyde, as well as aqueous urethane compounds having (thermally dissociable blocked) isocyanate groups and groups that are self-water-soluble (see Patent Document 6).

[0015] However, in recent years, there has been a growing demand to reduce the amount of resorcinol used as a water-soluble component in RFL adhesive compositions in order to reduce the environmental impact.

[0016] In order to address this issue, various adhesive compositions using water as a solvent by using polyphenols that do not contain resorcinol have been investigated and proposed.

[0017] For example, adhesive compositions for organic fibers that are composed of rubber latex and lignin resin (see Patent Document 7) and aqueous adhesive compositions based on rubber latex, polyphenols such as flavonoids, and aromatic polyaldehydes (see Patent Documents 8 and 9) are known as adhesive compositions that do not contain resorcinol or formaldehyde. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] U.S. Patent No. 2,128,229 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-263887 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-37251 [Patent Document 4] Japanese Patent Application Publication No. 9-12997 [Patent Document 5] International Publication No. 97 / 013818 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-241402 [Patent Document 7] International Publication No. 2018 / 003572 [Patent Document 8] International Publication No. 2013 / 017421 [Patent Document 9] Special Publication No. 2016-528337 [Non-patent literature]

[0019] [Non-Patent Document 1] Koichi Hakata, Network Polymer Vol.31, No.5, p.252(2010) Summary of the Invention [Problem to be solved by the invention]

[0020] However, when an adhesive composition comprising a simple mixture of rubber latex and lignin resin, as in Patent Document 7, is used as a resorcinol-free adhesive composition, the high tack of the rubber latex reduces the mechanical stability of the adhesive liquid under shear strain. As a result, for example, in the process of coating the organic fiber cord 1 with the adhesive composition 2 and drying and thermally curing it as shown in Figure 1, the adhesive composition 2 adheres more to the squeeze roll 5 and the rolls in the drying zone 6, resulting in a new problem of poor workability in the process.

[0021] Furthermore, adhesive compositions that do not contain resorcinol tend to have reduced adhesion because the surface of the adhesive coating becomes rough when they adhere to the above-mentioned equipment.Furthermore, because crosslinking between the latex component and the resorcinol-formaldehyde condensate is not achieved, there is also the problem that the adhesion between the organic fiber and the coated rubber composition is reduced compared to conventional RFL adhesive compositions.

[0022] Furthermore, as in Patent Document 8, when an aqueous adhesive composition is produced by mixing an aromatic dialdehyde such as terephthalaldehyde or 2,5-furandicarboxaldehyde, which has low solubility in water, with a polyphenol mixed with rubber latex, the aromatic dialdehyde is difficult to dissolve in water during production, and therefore the workability is insufficient.

[0023] Furthermore, the above-mentioned adhesive compositions not containing resorcinol have the problem of reducing the cord strength of organic fiber cords coated with the adhesive compositions.

[0024] Therefore, an object of the present invention is to provide an adhesive composition for organic fibers that can ensure the desired adhesiveness without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires that use the same. [Means for solving the problem]

[0025] In order to solve the above problems, the present inventors have conducted extensive research into the composition of adhesive compositions for organic fibers. As a result, they have found that by blending an acetoacetyl group-modified polyvinyl alcohol with a predetermined rubber latex, and preferably further blending one or more of an aqueous compound having a (thermally dissociable blocked) isocyanate group, an amine compound, and a polyphenol, it is possible to obtain an adhesive composition for organic fibers that can ensure the desired adhesive properties without using resorcinol and that does not impair workability during use, and have completed the present invention.

[0026] That is, the adhesive composition for organic fibers of the present invention is characterized by comprising (A) a rubber latex having an unsaturated diene, (B) an acetoacetyl group-modified polyvinyl alcohol, and (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group.

[0027] The adhesive composition for organic fibers of the present invention further comprises the following (D) and (E): (D) an amine compound, and (E) Polyphenols It is preferable that the adhesive composition for organic fibers of the present invention contains one or more compounds selected from the group consisting of: In the adhesive composition for organic fibers of the present invention, the degree of saponification of the (B) acetoacetyl group-modified polyvinyl alcohol is preferably 80 mol % or more.

[0028] In the adhesive composition for organic fibers of the present invention, the (C) aqueous compound having a (thermally dissociable blocked) isocyanate group is preferably a (C-1) water-dispersible (thermally dissociable blocked) isocyanate compound formed from an addition product of a polyisocyanate having an aromatic ring and a blocking agent having one or more active hydrogen groups.

[0029] Here, as the (C-1) water-dispersible (thermally dissociable blocked) isocyanate compound formed from an addition product of a polyisocyanate having an aromatic ring and a blocking agent having one or more active hydrogen groups, a blocked product of methylene diphenyl diisocyanate can be suitably used.

[0030] In the adhesive composition for organic fibers of the present invention, it is also preferable that the (C) aqueous compound having a (thermally dissociable blocked) isocyanate group is (C-2) an aqueous urethane compound having a (thermally dissociable blocked) isocyanate group.

[0031] Here, the (C-2) aqueous urethane compound having a (thermally dissociable blocked) isocyanate group includes: (α) an organic polyisocyanate compound having 3 or more and 5 or less functional groups and a number average molecular weight of 2,000 or less; (β) a compound having 2 or more and 4 or less active hydrogen groups and a number average molecular weight of 5,000 or less; (γ) a thermally dissociable blocking agent, and (δ) a compound having at least one active hydrogen group and at least one hydrophilic group that is anionic, cationic, or nonionic; The mixing ratio of each of (α), (β), (γ) and (δ) to the total amount is (α) is 40 mass% or more and 85 mass% or less, (β) is 5% by mass or more and 35% by mass or less, (γ) is 5% by mass or more and 35% by mass or less, and (δ) is 5% by mass or more and 35% by mass or less, and reacting the mixture to give a reaction product, When the molecular weight of the isocyanate group (-NCO) is 42, the composition ratio of the (thermally dissociable blocked) isocyanate group in the reaction product is preferably 0.5 mass % or more and 11 mass % or less.

[0032] Furthermore, the (C-2) aqueous urethane compound having a (thermally dissociable blocked) isocyanate group may be a compound represented by the following general formula (1): TIFF0007798424000001.tif17152[In formula (1), A is a residue of an organic polyisocyanate compound from which an active hydrogen group has been eliminated, X is a residue of a polyol compound having 2 or more and 4 or less hydroxyl groups and a number average molecular weight of 5,000 or less, from which an active hydrogen group has been eliminated; Y is a residue of the thermally dissociable blocking agent from which the active hydrogen group has been eliminated, Z is a residue of a compound having at least one active hydrogen group and at least one salt-forming group or a hydrophilic polyether chain, from which the active hydrogen group has been eliminated; n is an integer between 2 and 4, p+m is an integer between 2 and 4 (m≧0.25)

[0043] can also be suitably used.

[0033] Furthermore, in the adhesive composition for organic fibers of the present invention, a polyfunctional amine compound having two or more primary to tertiary amino groups is preferably used as the (D) amine compound.

[0034] Furthermore, in the adhesive composition for organic fibers of the present invention, the (E) polyphenol is preferably a plant-derived compound having multiple phenolic hydroxy groups in the molecule, and is also preferably lignin, tannin, tannic acid, a flavonoid, or a derivative thereof.

[0035] The adhesive composition for organic fibers of the present invention may be free of resorcinol.

[0036] The organic fiber material of the present invention is characterized in that the surface of an organic fiber is coated with an adhesive layer made of the adhesive composition for organic fibers. The adhesive composition for organic fibers of the present invention is particularly preferably used as a rubber-resin adhesive composition.

[0037] In the organic fiber material of the present invention, the organic fiber is preferably a cord formed by twisting together a plurality of filaments. In this case, the cord has a final twist and a primary twist, and more preferably, the twist coefficient of the primary twist is 1,300 to 2,500, and the twist coefficient of the final twist is 900 to 1,800.

[0038] In the organic fiber material of the present invention, the adhesive layer preferably has a dry mass of 0.5 to 6.0 mass % of the mass of the cord.

[0039] Furthermore, in the organic fiber material of the present invention, the organic fiber is preferably made of a polyester resin.

[0040] The rubber article of the present invention is characterized by being reinforced with the above organic fiber material.

[0041] The organic fiber-rubber composite of the present invention is a composite of organic fiber and rubber, characterized in that the organic fiber is coated with the adhesive composition for organic fibers described above.

[0042] The tire of the present invention is characterized by using the above organic fiber-rubber composite, particularly the organic fiber cord-rubber composite. [Effects of the Invention]

[0043] According to the present invention, it is possible to provide an adhesive composition for organic fibers that can ensure desired adhesiveness without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires that use the same. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 2 is a schematic diagram showing an example of a process for coating an organic fiber cord with an adhesive composition by dipping. [Figure 2] 1 is a schematic cross-sectional view showing an example of an organic fiber-rubber composite of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] The adhesive composition for organic fibers, organic fiber materials, rubber articles, organic fiber-rubber composites, and tires of the present invention will be described in detail below based on their embodiments. These descriptions are for the purpose of illustrating the present invention and are not intended to limit the present invention in any way.

[0046] When ranges are expressed herein, the endpoints of the range are included within the range unless otherwise stated.

[0047] [Adhesive composition for organic fibers] The adhesive composition for organic fibers of the present invention essentially contains (A) a rubber latex having an unsaturated diene and (B) an acetoacetyl group-modified polyvinyl alcohol, and preferably further contains the following (C) to (E): (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group; (D) an amine compound, and (E) Polyphenols The compound comprises one or more compounds selected from the group consisting of:

[0048] The adhesive composition for organic fibers of the present invention, with the above-described configuration, can achieve good adhesion without using resorcinol, and can particularly ensure good adhesion between organic fibers and a coating rubber composition. In the adhesive composition for organic fibers of the present invention, (A) a rubber latex having an unsaturated diene and, preferably, one or more compounds selected from the group consisting of (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) an amine compound, and (E) a polyphenol contribute to improved adhesion. Furthermore, the adhesive composition for organic fibers of the present invention uses (B) an acetoacetyl-modified polyvinyl alcohol, which suppresses the tack of the rubber latex, measured as the mechanical stability of the adhesive liquid under shear strain. This suppresses adhesion of the adhesive composition to rolls and the like, particularly during the process of coating organic fibers with the adhesive composition and drying and thermal curing, thereby improving workability. Therefore, the adhesive composition for organic fibers of the present invention can achieve the desired adhesion without using resorcinol, while also ensuring good workability during use. Furthermore, the adhesive composition for organic fibers of the present invention does not require the use of resorcinol, and therefore the environmental load can be reduced.

[0049] Therefore, the adhesive composition for organic fibers of the present invention can be one that does not contain resorcinol. Furthermore, the adhesive composition for organic fibers of the present invention preferably does not contain formaldehyde.

[0050] The adhesive composition for organic fibers of the present invention is particularly useful when applied to organic fiber cords, which will be described later.

[0051] <(A) Rubber Latex Having Unsaturated Diene> In the adhesive composition for organic fibers of the present invention, examples of the (A) rubber latex having an unsaturated diene include (A-1) a synthetic rubber latex having an unsaturated diene and (A-2) a natural rubber latex.

[0052] The (A-1) synthetic rubber latex having an unsaturated diene in the adhesive composition for organic fibers of the present invention means a synthetic rubber latex containing an unsaturated diene that is vulcanizable by sulfur.

[0053] In one embodiment of the present invention, the (A-1) unsaturated diene-containing synthetic rubber latex contained in the adhesive composition for organic fibers is a component for bonding an adhesive layer of the adhesive composition for organic fibers to a coating rubber composition serving as an adherend. The unsaturated diene-containing synthetic rubber latex is compatible with the rubber polymer contained in the coating rubber composition serving as an adherend, and further, the unsaturated diene moieties co-vulcanize to form a rubber co-vulcanization bond. As a result, the adhesive composition for organic fibers of the present invention, which contains the (A-1) unsaturated diene-containing synthetic rubber latex, can provide good adhesion between, for example, an organic fiber cord and a coating rubber composition.

[0054] The (A-1) synthetic rubber latex having an unsaturated diene is not limited, but examples thereof include styrene-butadiene copolymer rubber latex, vinylpyridine-styrene-butadiene copolymer rubber latex, carboxyl group-modified styrene-butadiene copolymer rubber latex, nitrile rubber latex, chloroprene rubber latex, etc. These may be used alone or in combination of two or more.

[0055] Among the above, vinylpyridine-styrene-butadiene copolymer rubber latex is preferred because it is a rubber latex that has been widely used in adhesive compositions and articles such as tires, and because it also provides good bonding between the adhesive layer and the rubber substrate in the adhesive composition for organic fibers of the present invention and has the advantages of being relatively soft and flexible, allowing the adhesive layer to be free from splitting and to accompany deformation of the organic fiber cord.

[0056] Furthermore, the content (solids content) of the synthetic rubber latex having an unsaturated diene (A-1) relative to the total solids in the adhesive composition for organic fibers of the present invention is not particularly limited, but is preferably 25% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. Furthermore, the content of the synthetic rubber latex having an unsaturated diene (A-1) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. When the content of the synthetic rubber latex having an unsaturated diene (A-1) is 25% by mass or more, the compatibility of the rubber polymers in the rubber composition to be adhered and the rubber latex contained in the adhesive composition becomes more suitable, resulting in better adhesion of the coating rubber in the organic fiber-rubber composite. On the other hand, when the content of the (A-1) unsaturated diene-containing synthetic rubber latex is 95 mass% or less, the amount of resin components contained as other components in the adhesive composition can be ensured to be relatively constant or more, and as a result, the cohesive failure resistance of the adhesive layer is sufficiently ensured, and failure within the adhesive layer is less likely to occur, making it possible to obtain sufficient adhesion.

[0057] The synthetic rubber latex containing the unsaturated diene (A-1) can be obtained, for example, by dissolving an emulsifier such as potassium rosinate in water, adding a mixture of monomers to the mixture, adding an electrolyte such as sodium phosphate and a peroxide as a polymerization initiator, polymerizing the mixture, and then, after a predetermined conversion rate is reached, adding a charge transfer agent to terminate the polymerization, and removing the remaining monomers. It is also preferable to use a chain transfer agent during the polymerization.

[0058] The emulsifier may be one or more of anionic surfactants such as alkali metal salts of fatty acids, alkali metal salts of rosin acid, formaldehyde-condensed sodium naphthalenesulfonate, sulfate esters of higher alcohols, alkylbenzenesulfonates, and aliphatic sulfonates, or nonionic surfactants such as alkyl esters, alkyl ethers, and alkylphenyl ethers of polyethylene glycol.

[0059] Among these emulsifiers, metal salts of rosin acid, especially alkali metal salts of rosin acid, are preferred. These can be used alone, i.e., by themselves, or in combination with two or more other emulsifiers. Rosin acid is a mixture of resin acids with similar chemical structures, primarily consisting of tricyclic diterpenes obtained from pine resin and other materials. These resin acids have three ring structures, two double bonds, and one carboxyl group, and the double bond portion contains a highly reactive functional group that can esterify with the methylol end of unsaturated carboxylic acids or resol-type phenolic resins at the carboxyl group portion.

[0060] The amount of such an emulsifier used is usually 0.1 to 8 parts by mass, and preferably 1 to 5 parts by mass, per 100 parts by mass of all the monomers used in the latex polymerization.

[0061] As the polymerization initiator, for example, water-soluble initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate, redox initiators, and oil-soluble initiators such as benzoyl peroxide can be used. Among these, potassium persulfate is preferred.

[0062] Examples of the chain transfer agent include monofunctional alkyl mercaptans such as n-hexyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, and t-hexyl mercaptan; bifunctional mercaptans such as 1,10-decanedithiol and ethylene glycol dithioglycolate; trifunctional mercaptans such as 1,5,10-caneditrithiol and trimethylolpropane tristhioglycolate; tetrafunctional mercaptans such as pentaerythritol tetrakisthioglycolate; disulfides; halogen compounds such as carbon tetrachloride, carbon tetrabromide, and ethylene bromide; α-methylstyrene dimer, terpinolene, α-terpinene, dipentene, and allyl alcohol. These may be used alone or in combination of two or more.

[0063] Of these chain transfer agents, alkyl mercaptans are preferred, and n-octyl mercaptan and t-dodecyl mercaptan are more preferred, with t-dodecyl mercaptan being particularly preferred.

[0064] The amount of such a chain transfer agent used is usually 0.01 to 5 parts by mass, and preferably 0.1 to 3 parts by mass, per 100 parts by mass of all the monomers used in the latex polymerization.

[0065] In addition to the above-mentioned components, the latex may contain, if necessary, general-purpose additives such as antioxidants such as hindered phenols, silicone-based, higher alcohol-based and mineral oil-based antifoaming agents, reaction terminators and antifreezing agents.

[0066] <<Vinylpyridine-styrene-butadiene copolymer rubber latex>> The vinylpyridine-styrene-butadiene copolymer rubber latex is a terpolymer of a vinylpyridine-based monomer, a styrene-based monomer, and a conjugated diene-based butadiene monomer, and may further contain other monomers copolymerizable with these monomers.

[0067] Here, the vinylpyridine monomer includes vinylpyridine and substituted vinylpyridines in which hydrogen atoms in the vinylpyridine are substituted with substituents. Examples of such vinylpyridine monomers include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and 5-ethyl-2-vinylpyridine, and among these, 2-vinylpyridine is preferred. These vinylpyridine monomers may be used alone or in combination of two or more.

[0068] The styrene-based monomer includes styrene and substituted styrenes in which the hydrogen atoms in the styrene are replaced with substituents. Examples of the styrene-based monomer include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diynopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, and hydroxymethylstyrene. Among these, styrene is preferred. These styrene-based monomers may be used alone or in combination of two or more.

[0069] Examples of the conjugated diene-based butadiene monomer include aliphatic conjugated butadiene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene, and among these, 1,3-butadiene is preferred. These conjugated diene-based butadiene monomers may be used alone or in combination of two or more.

[0070] The vinylpyridine-styrene-butadiene copolymer rubber latex can be synthesized by a known method, specifically, for example, the method described in JP-A-9-78045, which was studied by the present inventors. By using these methods, various compositions and intra-particle structures can be imparted to the same particle of the vinylpyridine-styrene-butadiene copolymer rubber latex, such as copolymers with uniform or different composition ratios.

[0071] Regarding the vinylpyridine-styrene-butadiene copolymer rubber latex, examples of commercially available copolymers having a uniform monomer mixing ratio within the same particle include Nipol 2518 manufactured by Nippon Zeon Co., Ltd. and Piratex manufactured by Nippon A&L Co., Ltd. In addition, examples of commercially available copolymers having different monomer mixing ratios within the same particle include V0658 manufactured by JSR Corporation. All of these can be used as the unsaturated diene-containing synthetic rubber latex (A-1) in the adhesive composition for organic fibers of the present invention.

[0072] In the vinylpyridine-styrene-butadiene copolymer rubber latex, the vinylpyridine:styrene:butadiene monomer ratio is not particularly limited. However, it is preferable that the copolymer constituting the vinylpyridine-styrene-butadiene copolymer particles contains a copolymer obtained by polymerizing a monomer mixture consisting of 5-20% by weight of vinylpyridine, 10-40% by weight of styrene, and 45-75% by weight of butadiene. A vinylpyridine content of 5% by weight or more provides an appropriate amount of pyridine moieties that accelerate vulcanization within the rubber component, increasing the degree of crosslinking by sulfur and further improving the adhesive strength of the entire adhesive layer. A vinylpyridine content of 20% by weight or less prevents the rubber from becoming over-crosslinked, resulting in a hard adhesive. Furthermore, a styrene content of 10% by weight or more ensures sufficient strength of the latex particles and adhesive layer, further improving adhesive strength. A styrene content of 40% by weight or less leads to adequate co-vulcanization between the adhesive layer and the rubber substrate, while still ensuring sufficient adhesive strength. Furthermore, if the butadiene content is 45% by mass or more, more sufficient crosslinking can be formed, and if it is 75% by mass or less, the crosslinking is moderate and durability against changes in volume and modulus can be well ensured. The composition ratio of the vinylpyridine:styrene:butadiene monomer mixture can be suitably set to, for example, 15:15:70.

[0073] In the present invention, as the (A) rubber latex having an unsaturated diene, in addition to the (A-1) synthetic rubber latex having an unsaturated diene, (A-2) natural rubber latex can be used. The natural rubber latex is not particularly limited, and examples thereof include field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized latex treated with a surfactant or enzyme, and combinations thereof. Among these, it is preferable to use field latex.

[0074] The content of (A-2) natural rubber latex (solids content) relative to the total solids in the adhesive composition of the present invention is not particularly limited, but is preferably 25% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. The content of (A-2) natural rubber latex is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0075] <(B) Acetoacetyl group-modified polyvinyl alcohol> The (B) acetoacetyl group-modified polyvinyl alcohol can be obtained by reacting a polyvinyl alcohol resin with diketene by a known method, etc. For example, although the production method is not particularly limited, it can be obtained by a method in which diketene is added after dispersing a polyvinyl alcohol resin in a solvent such as acetic acid, a method in which diketene is added after dissolving a polyvinyl alcohol resin in a solvent such as dimethylformamide or dioxane, or a method in which diketene gas or liquid diketene is brought into contact with a polyvinyl alcohol resin.

[0076] In the present invention, the (B) acetoacetyl group-modified polyvinyl alcohol can usually be one having an acetoacetyl group modification degree of 0.05 mol% or more. The acetoacetyl group modification degree of the (B) acetoacetyl group-modified polyvinyl alcohol is preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, and most preferably 2 to 15 mol%. When the acetoacetyl group modification degree is 0.05 mol% or more, the adhesive layer can have sufficient water resistance.

[0077] The polyvinyl alcohol resin used in (B) acetoacetyl group-modified polyvinyl alcohol is obtained by saponifying a polyvinyl acetate resin. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate with other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The polyvinyl alcohol resin may also be further modified; for example, polyvinyl polymers or polyvinyl acetals modified with aldehydes may also be used.

[0078] The degree of saponification of (B) acetoacetyl group-modified polyvinyl alcohol is not particularly limited as long as (B) acetoacetyl group-modified polyvinyl alcohol is water-soluble, but is preferably 80 mol% or more, more preferably 85 to 100 mol%, and particularly preferably 98 mol% or more, depending on the degree of saponification of the polyvinyl alcohol resin contained therein. When the (B) acetoacetyl group-modified polyvinyl alcohol has a degree of saponification of 80 mol% or more, sufficient water solubility is exhibited, thereby preventing the occurrence of problems such as reduced workability of the adhesive composition liquid.

[0079] The degree of polymerization of (B) acetoacetyl group-modified polyvinyl alcohol is not particularly limited as long as the acetoacetyl group-modified polyvinyl alcohol is soluble in water, but is preferably in the range of 100 to 10,000, and more preferably 200 to 5,000. When the molecular weight of (B) acetoacetyl group-modified polyvinyl alcohol is 10,000 or less, the occurrence of a problem in which the viscosity of the adhesive composition liquid increases and workability decreases can be suppressed.

[0080] (B) Commercially available acetoacetyl group-modified polyvinyl alcohols are not particularly limited, but examples thereof include the Gohsenex Z series manufactured by Mitsubishi Chemical Corporation, such as Z-100, Z-200, Z-210, Z-220, Z-300, Z-320, and Z-410.

[0081] Incidentally, (B) acetoacetyl group-modified polyvinyl alcohol has been known in the past as a condensation agent with various materials such as amines, hydrazides, aldehydes, and metal salts in water, or as a self-crosslinking agent by heat treatment, and has been widely used in applications such as an emulsifier for vinyl acetate emulsions, a condensation agent for coatings on coated paper and uncoated paper that require water resistance, and applications for imparting water resistance to adhesives, binders, etc. Although there have been cases in which (B) acetoacetyl group-modified polyvinyl alcohol has been studied as an adhesive composition for resin crosslinking, there have been almost no known cases in which it has been studied as an adhesive composition for bonding rubber and resin by mixing with a rubber component such as rubber latex.

[0082] In conventional adhesive compositions containing resorcinol and formaldehyde, the resorcinol and formaldehyde form a resol-type resorcinol-formaldehyde condensate between rubber latex particles dispersed in an aqueous solvent, and on the surface of the rubber latex in the adhesive composition, the methylol groups of the resorcinol-formaldehyde condensate add to rosinate salts, etc., used as emulsifiers, and co-condense; this results in a coating of chemically crosslinked phenolic resin, which suppresses the adhesiveness of the rubber latex.

[0083] On the other hand, in the adhesive composition for organic fibers of the present invention, (B) acetoacetyl group-modified polyvinyl alcohol functions as an emulsifier to coat the surface of the synthetic rubber latex having an unsaturated diene, forming a complex with the rubber latex having an unsaturated diene, and this coating can have the effect of suppressing the tackiness of the rubber latex having an unsaturated diene.

[0084] As a result, the adhesive composition for organic fibers of the present invention containing (B) acetoacetyl group-modified polyvinyl alcohol suppresses the tackiness of rubber latex, which is measured as the mechanical stability of the adhesive liquid under shear strain. This makes it possible to suppress adhesion of the adhesive composition for organic fibers to rolls and the like in the process of coating an organic fiber cord with the adhesive composition and drying and thermally curing the organic fiber cord, thereby improving workability.

[0085] Furthermore, in the process of coating the surface of an organic fiber cord with the adhesive composition for organic fibers of the present invention and drying and heat curing the coated rubber composition, (B) acetoacetyl group-modified polyvinyl alcohol not only chemically crosslinks with the self-crosslinking agent during heat treatment, but also chemically crosslinks with other components, if any, contained in the adhesive composition for organic fibers of the present invention, thereby improving the adhesion between the organic fiber and the coating rubber composition.

[0086] For example, when the adhesive composition for organic fibers of the present invention contains (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group, the hydroxyl groups derived from the polyvinyl alcohol of (B) acetoacetyl group-modified polyvinyl alcohol chemically crosslink with the component of the isocyanate group (NCO group) dissociated by the blocking agent for the (thermally dissociable blocked) isocyanate group of component (C), thereby improving the adhesion between the organic fiber and the coating rubber composition.

[0087] In addition, for example, the acetoacetyl group of (B) acetoacetyl group-modified polyvinyl alcohol can be chemically crosslinked with the (D) amine compound component to further improve the adhesion between the organic fiber and the coating rubber composition.

[0088] The acetoacetyl group-modified polyvinyl alcohol (B) used in the present invention is available in the form of a powder or an aqueous solution, but when used in the adhesive composition for organic fibers of the present invention, it is preferably used as an aqueous solution.

[0089] The content (solid content) of the (B) acetoacetyl group-modified polyvinyl alcohol relative to the total solid content of the adhesive composition for organic fibers of the present invention is not particularly limited, but is preferably 0.05% by mass or more and 25% by mass or less, more preferably 0.2% by mass or more and 15% by mass or less, and even more preferably 0.4% by mass or more and 12% by mass or less.

[0090] When the content of the (B) acetoacetyl group-modified polyvinyl alcohol is 0.05% by mass or more, its function as an emulsifier can suppress the tackiness of the rubber latex by coating the synthetic rubber latex containing an unsaturated diene. Furthermore, when the content of the (B) acetoacetyl group-modified polyvinyl alcohol is 0.2% by mass or more, crosslinking of the adhesive composition for organic fibers of the present invention increases the fracture resistance of the adhesive layer, thereby advantageously improving the adhesion between the organic fiber and the coating rubber composition. Furthermore, when the content of the (B) acetoacetyl group-modified polyvinyl alcohol is 25% by mass or less, the amount of (B) acetoacetyl group-modified polyvinyl alcohol contained in the liquid adhesive composition for organic fibers of the present invention is not too high, thereby suppressing a decrease in workability due to an increase in the liquid viscosity of the adhesive composition.

[0091] <(C), (D), and (E)> The adhesive composition for organic fibers of the present invention preferably further contains one or more compounds selected from the group consisting of (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) an amine compound, and (E) a polyphenol.

[0092] In the adhesive composition for organic fibers of the present invention, the aqueous compound having a (thermally dissociable blocked) isocyanate group (C) functions as a crosslinking agent, and contributes to improving the adhesion between the organic fiber and the coating rubber composition, for example.

[0093] Furthermore, the (D) amine compound can improve the adhesion between the organic fiber and the coating rubber composition by, for example, chemically crosslinking with the acetoacetyl group of the (B) acetoacetyl group-modified polyvinyl alcohol contained in the adhesive composition for organic fibers of the present invention.

[0094] Furthermore, the (E) polyphenol has the function of improving the affinity between the adhesive composition for organic fibers and the surface of organic fibers, and as a result, the adhesion between the organic fibers and the coating rubber composition can be improved.

[0095] Therefore, (C) the aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) the amine compound, and (E) the polyphenol all contribute to improving adhesion, for example, improving adhesion between the organic fiber and the coating rubber composition.

[0096] <(C) Aqueous Compound Having a (Thermally Dissociable Blocked) Isocyanate Group> The (thermally dissociable blocked) isocyanate group of the aqueous compound (C) having a (thermally dissociable blocked) isocyanate group means a thermally dissociable blocked isocyanate group or an isocyanate group.

[0097] Specifically, the (thermally dissociable blocked) isocyanate group includes (i) a thermally dissociable blocked isocyanate group formed by reaction of an isocyanate group with a thermally dissociable blocking agent for the isocyanate group, (ii) an isocyanate group that has not reacted with the thermally dissociable blocking agent for the isocyanate group, (iii) an isocyanate group formed by dissociation of a thermally dissociable blocking agent from a thermally dissociable blocked isocyanate group, and (iv) an isocyanate group.

[0098] The term "aqueous" in the above-mentioned (C) aqueous compound having a (thermally dissociable blocked) isocyanate group refers to water-soluble or water-dispersible. Furthermore, the term "water-soluble" does not necessarily mean complete water-solubility, but rather means partial water-solubility or no phase separation in the aqueous solution of the adhesive composition.

[0099] The (C) aqueous compound having a (thermally dissociable, blocked) isocyanate group is preferably a (C-1) water-dispersible (thermally dissociable, blocked) isocyanate compound (hereinafter simply referred to as "component (C-1)") consisting of an addition product of a polyisocyanate having an aromatic ring and a blocking agent having one or more active hydrogen groups. In this case, when the adhesive composition for organic fibers is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition becomes better.

[0100] Here, with respect to the component (C-1), the active hydrogen group refers to a group containing hydrogen that becomes active hydrogen (atomic hydrogen (hydrogen radical) and hydride ion (hydride)) under suitable conditions. Examples of the active hydrogen group include an amino group and a hydroxyl group.

[0101] The thermally dissociable blocking agent is not particularly limited as long as it is a blocking agent compound that can protect the isocyanate groups from any chemical reaction while dissociating the blocking agent by heat treatment as necessary to restore the isocyanate groups. Specifically, in the step shown in Figure 1, the temperature of the heat treatment for thermal curing after the adhesive treatment liquid is applied and dried is preferably a thermal dissociation temperature at which the crosslinking reactivity of the isocyanate groups that have been blocked with the thermally dissociable blocking agent and whose reactivity has been suppressed can be restored.

[0102] Examples of the blocking agent include, but are not limited to, alcohols, phenols, active methylenes, oximes, lactams, amines, etc., and specifically include lactams such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; phenols such as phenol, cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, dinonylphenol, thiophenol, chlorophenol, and amylphenol; oximes such as methyl ethyl ketoxime, acetoxime, acetophenone oxime, benzophenone oxime, and cyclohexanone oxime; alcohols such as methanol, ethanol, butanol, isopropyl alcohol, butyl alcohol, and cyclohexanol; malonic acid dialkyl esters such as dimethyl malonate and diethyl malonate; active methylenes such as methyl acetoacetate, ethyl acetoacetate, and acetylacetone; and mercaptans such as butyl mercaptan and dodecyl mercaptan. Examples of suitable amines include captans; amides such as acetanilide and acetic acid amide; imides such as succinimide, phthalimide, and maleimide; sulfites such as sodium bisulfite; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; pyrazoles such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; amines such as dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, dicyclohexylamine, diphenylamine, xylidine, N,N-diethylhydroxyamine, N,N'-diphenylformamidine, 2-hydroxypyridine, 3-hydroxypyridine, and 2-mercaptopyridine; and triazoles such as 1,2,4-triazole. Mixtures of two or more of these may also be used.

[0103] Among these blocking agents, phenol, ε-caprolactam, and ketoxime can be preferably used, as they are easily thermally dissociated by heating to stably obtain thermal curing of the adhesive composition for organic fibers.

[0104] The component (C-1) specifically includes aromatic polyisocyanates or aromatic aliphatic polyisocyanates, and examples of aromatic isocyanates include phenylene diisocyanates such as m-phenylene diisocyanate and p-phenylene diisocyanate; tolylene diisocyanates such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate (TDI); 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI); dialkyl Examples of suitable aromatic polyisocyanates include diphenylmethane diisocyanates such as diphenylmethane diisocyanate and tetraalkyldiphenylmethane diisocyanate; polymethylene polyphenyl polyisocyanate (polymeric MDI); m- or p-isocyanatophenylsulfonyl isocyanates; diisocyanatobiphenyls such as 4,4'-diisocyanatobiphenyl and 3,3'-dimethyl-4,4'-diisocyanatobiphenyl; naphthalene diisocyanates such as 1,5-naphthylene diisocyanate; etc. Examples of suitable aromatic polyisocyanates include xylylene diisocyanates such as m-xylylene diisocyanate, p-xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate; diethylbenzene diisocyanate; and α,α,α,α-tetramethylxylylene diisocyanate (TMXDI). Further examples include modified products such as carbodiimides, polyols, and allophanates of the above polyisocyanates.

[0105] Among these polyisocyanates containing an aromatic ring in the molecule, aromatic isocyanates are preferred from the viewpoint of the cord bundling properties of the adhesive composition for organic fibers, more preferably tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or polymethylene polyphenyl polyisocyanate (polymeric MDI), and particularly preferably diphenylmethane diisocyanates (MDIs). By using a blocked methylene diphenyl isocyanate, especially a blocked methylene diphenyl diisocyanate (diphenylmethane diisocyanate), as component (C-1), the adhesion between the organic fibers and the coating rubber composition becomes better when the adhesive composition for organic fibers is used on the organic fibers.

[0106] Furthermore, it is more preferable that the aqueous compound having a (thermally dissociable blocked) isocyanate group (C) is an aqueous urethane compound having a (thermally dissociable blocked) isocyanate group (C-2) (hereinafter simply referred to as "component (C-2)"). In this case, when the adhesive composition for organic fibers is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition is improved. Details of the component (C-2) will be described later for convenience of explanation.

[0107] The content (solids content) of the aqueous compound having (C) a (thermally dissociable blocked) isocyanate group relative to the total solids content of the adhesive composition for organic fibers of the present invention is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The content of the aqueous compound having (C) a (thermally dissociable blocked) isocyanate group is preferably 75% by mass or less, more preferably 60% by mass or less, and even more preferably 45% by mass or less. A content of the aqueous compound having (C) a (thermally dissociable blocked) isocyanate group of 5% by mass or more improves the adhesion between the organic fiber and the coating rubber composition. A content of the aqueous compound having (C) a (thermally dissociable blocked) isocyanate group of 75% by mass or less ensures that the amount of other components, such as rubber latex, blended into the adhesive composition for organic fibers is at a certain level or more, resulting in better adhesion to the rubber substrate.

[0108] In conventional adhesive compositions for organic fibers containing resorcinol and formaldehyde, a sea-island structure is formed in which rubber latex particles (likely islands) are dispersed in a phenolic resin (likely the sea) formed by co-condensation of resorcinol and formaldehyde, thereby achieving good adhesion between the phenolic resin that coats the surface of the organic fiber and the organic fiber.

[0109] On the other hand, in a preferred embodiment of the adhesive composition for organic fibers of the present invention, the aqueous compound having a (thermally dissociable blocked) isocyanate group (C) acts as an adhesion promoter, instead of the phenolic resin obtained by co-condensation of resorcinol and formaldehyde, due to the following two functional effects (a) and (b): As a result, in the adhesive composition for organic fibers, the aqueous compound having a (thermally dissociable blocked) isocyanate group (C) contributes to the characteristic of good adhesion between the organic fiber and the coating rubber composition.

[0110] (a) The functional effect of distributing the aqueous compound near the interface between the organic fiber and the adhesive layer of the adhesive composition for organic fiber, thereby promoting adhesion between the organic fiber and the adhesive layer. (b) Within the adhesive layer of the adhesive composition for organic fibers, a three-dimensional network structure is formed by crosslinking with the isocyanate groups of the compound having the (thermally dissociable blocked) isocyanate group, thereby reinforcing the adhesive layer.

[0111] In one embodiment of the adhesive composition for organic fibers of the present invention, an example of the principles of the functional effects (a) and (b) of the aqueous compound (C) having a (thermally dissociable blocked) isocyanate group as an adhesion promoter will be described in detail below.

[0112] <<(a) Functional effect as an adhesion promoter>> Polyester synthetic resin materials, such as polyethylene terephthalate, which are widely used as organic fibers, consist of flat, linear polymer chains. The surfaces of the polymer chains and the gaps between the polymer chains have a π-electron atmosphere derived from aromatic groups contained in the polymer chains. Furthermore, polyesters have particularly fewer hydroxyl groups on their surfaces than 6,6-nylon.

[0113] Therefore, organic fiber adhesive compositions used for organic fibers made of polyester have conventionally contained, as an adhesion promoter, molecules with a planar structure (a portion that easily diffuses into organic fibers) having aromatic rings with aromatic π electrons on their sides, with the aim of dispersing the organic fiber adhesive composition into the gaps between the polymer chains of the organic fibers and ensuring that the adhesive layer of the organic fiber adhesive composition adheres closely to the surface of the polymer chains of the organic fibers in order to obtain sufficient adhesive strength.

[0114] <<(b) Functional effect as an adhesion promoter>> In the adhesive layer containing the component (C-1), as described above, a covalent bond is formed by isocyanate crosslinking between the hydroxyl group of the acetoacetyl group-modified polyvinyl alcohol (B) contained in the adhesive composition for organic fibers and the isocyanate from which the blocking agent has been dissociated by heat treatment, thereby strengthening the adhesion provided by the adhesive composition for organic fibers.

[0115] The particle size of the component (C-1) is preferably 0.01 to 0.50 μm. When the particle size of the component (C-1) is 0.50 μm or less, the smaller the particle size, the less likely the component (C-1) will settle in the liquid, and the less likely it will be dispersed non-uniformly in the adhesive layer.

[0116] On the other hand, in the case of (C-2) an aqueous urethane compound having a (thermally dissociable blocked) isocyanate group, due to its high water solubility, sedimentation of components in the adhesive composition liquid is unlikely to occur, and the components are unlikely to become non-uniform even when the adhesive composition is stored stationary, so that adhesion is stable over time, etc., and is therefore preferred.

[0117] <<Thermal dissociation blocking agent, water-based urethane compound>> The thermally dissociable blocking agent of component (C-2) is not particularly limited as long as it is a blocking agent compound that can protect the isocyanate group from any chemical reaction while dissociating the blocking agent by heat treatment as necessary to restore the isocyanate group. Specific examples of the thermally dissociable blocking agent include the same compounds as the blocking agents described above for component (C-1). Preferred examples include phenols such as phenol, thiophenol, chlorophenol, cresol, resorcinol, p-sec-butylphenol, p-tert-butylphenol, p-sec-amylphenol, p-octylphenol, and p-nonylphenol; secondary or tertiary alcohols such as isopropyl alcohol and tert-butyl alcohol; aromatic secondary amines such as diphenylamine and xylidine; and phthalic acid imide. caprolactams such as ε-caprolactam; diethyl malonate, dimethyl malonate, and other dialkyl malonates, acetylacetone, acetoacetic acid alkyl esters, and other active methylene compounds; acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, and other oximes; basic nitrogen compounds such as 3-hydroxypyridine, 1,2-pyrazole, 3,5-dimethylpyrazole, 1,2,4-triazole, diisopropylamine, and N,N'-diphenylformamidine, and acidic sodium sulfite.

[0118] Among these blocking agents, phenol, ε-caprolactam, and ketoxime can be preferably used, as they are easily thermally dissociated by heating to stably obtain thermal curing of the adhesive composition for organic fibers.

[0119] Here, the term "aqueous" in the aqueous urethane compound means that the compound is water-soluble or water-dispersible. Furthermore, the term "water-soluble" does not necessarily mean that the compound is completely water-soluble, but rather that the compound is partially water-soluble or does not undergo phase separation in the aqueous solution of the organic fiber adhesive composition.

[0120] The urethane compound of the aqueous urethane compound is a compound having a covalent bond formed between the nitrogen of an amine and the carbon of a carbonyl group, and means a compound represented by the following general formula (2). TIFF0007798424000002.tif26152In the above formula (2), R and R' represent hydrocarbon groups.

[0121] The molecular weight of the aqueous urethane compound having the (thermally dissociable blocked) isocyanate group (C-2) is not particularly limited as long as it can maintain its aqueous nature, and the number average molecular weight is preferably 1,500 to 100,000, and particularly preferably 9,000 or less.

[0122] As mentioned above, the method for synthesizing the component (C-2) is not particularly limited, and can be a known method such as the method described in JP-A-63-51474.

[0123] <<(C-2) Preferred Embodiments of Aqueous Urethane Compound Having a (Thermally Dissociable Blocked) Isocyanate Group>> A preferred embodiment of the component (C-2) is a reaction product obtained by mixing and reacting (α) an organic polyisocyanate compound having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less, (β) a compound having 2 to 4 active hydrogen groups and a number-average molecular weight of 5,000 or less, (γ) a thermally dissociable blocking agent, and (δ) a compound having at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group in a predetermined mixing ratio, wherein the proportion of (thermally dissociable blocked) isocyanate groups in the reaction product is 0.5 to 11 mass % when the molecular weight of the isocyanate group (—NCO) is 42. In this case, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coating rubber composition is improved. This is because such a component (C-2) has both a moiety consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic moiety having a hydrophilic group, and therefore has the advantage of increasing the self-water solubility of the urethane compound.

[0124] The mixing ratio of each of (α), (β), (γ), and (δ) relative to the total amount is 40% by mass or more and 85% by mass or less for (α), 5% by mass or more and 35% by mass or less for (β), 5% by mass or more and 35% by mass or less for (γ), and 5% by mass or more and 35% by mass or less for (δ).

[0125] The (α) organic polyisocyanate compound having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less is not particularly limited, but is preferably an aromatic polyisocyanate compound and its oligomer, or may be other aliphatic, alicyclic, or heterocyclic polyisocyanate compounds and their oligomers. This is because the (C-2) component, which is the reaction product obtained after reacting such (α) organic polyisocyanate compound having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less, is more easily dispersed in the gaps between the polymer chains of the organic fiber.

[0126] Specific examples of aliphatic polyisocyanate compounds include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate. Specific examples of alicyclic polyisocyanate compounds include cyclobutane diisocyanate, cyclobutane diisocyanate, and cyclobutane diisocyanate. Examples of heterocyclic polyisocyanate compounds include 1,3,5-tris(2'-isocyanatomethyl)cyclohexane, ... Examples of aromatic polyisocyanate compounds include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, m-tetramethylxylylene diisocyanate, p-tetramethylxylylene diisocyanate, methine tris(4-phenylisocyanate), tris(4-isocyanatophenyl)methane, thiophosphate tris(4-isocyanatophenyl ester), 3-isopropenyl-α',α'-dimethylbenzyl isocyanate, and oligomer mixtures thereof; and modified products of these polyisocyanate compounds, such as carbodiimide, polyol, and allophanate.

[0127] Among these, aromatic polyisocyanate compounds are preferred, and particularly preferred are methylene diphenyl polyisocyanate, polyphenylene polymethylene polyisocyanate, etc. In particular, polyphenylene polymethylene polyisocyanate having a number average molecular weight of 2,000 or less is preferred, and polyphenylene polymethylene polyisocyanate having a number average molecular weight of 1,000 or less is particularly preferred. This is because component (C-2), which is a reaction product obtained after reacting such organic polyisocyanate compound (α) having 3 to 5 functional groups and a number average molecular weight of 2,000 or less, is more likely to disperse in the gaps between polymer chains of organic fibers.

[0128] The above (β) compound having two or more and four or less active hydrogen groups and a number average molecular weight of 5,000 or less is not particularly limited, but specific examples thereof include compounds selected from the group consisting of the following (i) to (vii): (i) Polyhydric alcohols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (ii) polyamines having 2 to 4 primary and / or secondary amino groups and a number average molecular weight of 5,000 or less; (iii) Amino alcohols having 2 to 4 primary and / or secondary amino groups and a hydroxyl group and a number average molecular weight of 5,000 or less; (iv) polyester polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (v) Polybutadiene polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less, and copolymers thereof with other vinyl monomers; (vi) Polychloroprene polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less, and copolymers thereof with other vinyl monomers, (vii) Polyether polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less. C2-C4 alkylene oxide polyadducts of polyamines, polyphenols and amino alcohols, C2-C4 alkylene oxide polyadducts of C3 or higher polyalcohols, C2-C4 alkylene oxide copolymers, or C3-C4 alkylene oxide polymers.

[0129] Here, with respect to the component (C-2), the active hydrogen group refers to a group containing hydrogen that becomes active hydrogen (atomic hydrogen (hydrogen radical) and hydride ion (hydride)) under suitable conditions. Examples of the active hydrogen group include an amino group and a hydroxyl group.

[0130] The compound having at least one active hydrogen group and at least one anionic hydrophilic group (δ) among the compounds having at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group is not particularly limited, but examples thereof include taurine, N-methyltaurine, N-butyltaurine, aminosulfonic acids such as sulfanilic acid, and aminocarboxylic acids such as glycine and alanine.

[0131] The method for synthesizing the component (C-2) by mixing and reacting the above (α), (β), (γ), and (δ) is not particularly limited, but can be a known method such as the method described in JP-A-63-51474.

[0132] <<(C-2) Another Preferred Embodiment of Aqueous Urethane Compound Having a (Thermally Dissociable Blocked) Isocyanate Group>> Another preferred embodiment of the component (C-2) is a reaction product obtained by mixing and reacting (α) an organic polyisocyanate compound having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less, (β) a compound having 2 to 4 active hydrogen groups and a number-average molecular weight of 5,000 or less, (γ) a thermally dissociable blocking agent, (δ) a compound having at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group, and (ε) a compound other than (α), (β), (γ), and (δ) that contains an active hydrogen group, in a predetermined mixing ratio, wherein the proportion of (thermally dissociable blocked) isocyanate groups in the reaction product is 0.5 to 11 mass % when the molecular weight of the isocyanate group (—NCO) is 42. This is because such a component (C-2) has both a moiety consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic moiety having a hydrophilic group, and therefore has the advantage of increasing the self-water solubility of the urethane compound.

[0133] The mixing ratio of each of (α), (β), (γ), (δ), and (ε) relative to the total amount is 40 mass% or more and less than 85 mass% for (α), 5 mass% or more and 35 mass% or less for (β), 5 mass% or more and 35 mass% or less for (γ), 5 mass% or more and 35 mass% or less for (δ), and more than 0 mass% and 45 mass% or less for (ε).

[0134] Here, (α) the organic polyisocyanate compound having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less, (β) the compound having 2 to 4 active hydrogen groups and a number-average molecular weight of 5,000 or less, (γ) the thermally dissociable blocking agent, and (δ) the compound having at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group are as described in the above section <<(C-2) Preferred Embodiments of Aqueous Urethane Compound Having (Thermally Dissociable Blocked) Isocyanate Groups>>, except for their mixing ratios.

[0135] The method for synthesizing the component (C-2) by mixing and reacting the above (α), (β), (γ), (δ), and (ε) is not particularly limited, but can be a known method such as the method described in JP-A-63-51474.

[0136] <<(C-2) Yet Another Preferred Embodiment of Aqueous Urethane Compound Having a (Thermally Dissociable Blocked) Isocyanate Group>> Yet another preferred embodiment of the component (C-2) is a compound represented by the following general formula (1): TIFF0007798424000003.tif17152[In formula (1), A is a residue of an organic polyisocyanate compound from which an active hydrogen group has been eliminated, X is a residue of a polyol compound having 2 or more and 4 or less hydroxyl groups and a number average molecular weight of 5,000 or less, from which an active hydrogen group has been eliminated; Y is a residue of the thermally dissociable blocking agent from which the active hydrogen group has been eliminated, Z is a residue of a compound having at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain, from which the active hydrogen group has been eliminated; n is an integer between 2 and 4, p+m is an integer between 2 and 4 (m≧0.25)

[0033] In this case, too, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition is improved. This is because the component (C-2) has both a moiety consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic moiety having a hydrophilic group, which has the advantage of increasing the self-water solubility of the urethane compound.

[0137] Here, the organic polyisocyanate compound A in general formula (1), which is the residue of the organic polyisocyanate compound from which the active hydrogen group has been eliminated, preferably contains an aromatic ring, because this allows the component (C-2) to be more easily dispersed in the gaps between the polymer chains of the organic fiber.

[0138] Although not particularly limited, specific examples include methylene diphenyl polyisocyanate, polyphenylene polymethylene polyisocyanate, etc. Polyphenylene polymethylene polyisocyanate having a number average molecular weight of 6,000 or less is preferred, and polyphenylene polymethylene polyisocyanate having a number average molecular weight of 4,000 or less is particularly preferred.

[0139] The polyol compound having two or more and four or less hydroxyl groups and a number average molecular weight of 5,000 or less, which is the residue obtained by eliminating the active hydrogen group from a polyol compound having two or more and four or less hydroxyl groups and a number average molecular weight of 5,000 or less, represented by X in general formula (1), is not particularly limited, and specific examples thereof include compounds selected from the group consisting of the following (i) to (vi): (i) Polyhydric alcohols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (ii) amino alcohols having two to four primary and / or secondary amino groups and a hydroxyl group and a number average molecular weight of 5,000 or less; (iii) polyester polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (iv) Polybutadiene polyols and copolymers thereof with other vinyl monomers, each having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (v) Polychloroprene polyols and copolymers thereof with other vinyl monomers, having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less; (vi) Polyether polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less. C2-C4 alkylene oxide polyadducts of polyamines, polyphenols and amino alcohols, C2-C4 alkylene oxide polyadducts of C3 or higher polyalcohols, C2-C4 alkylene oxide copolymers, or C3-C4 alkylene oxide polymers.

[0140] The component (C-2) is not particularly limited, but commercially available products such as Elastron BN27, BN77, and BN11 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. can also be used. Of these, Elastron BN77 is preferred.

[0141] <(D) Amine Compound> One preferred embodiment of the adhesive composition for organic fibers of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) an acetoacetyl group-modified polyvinyl alcohol, and (D) an amine compound.

[0142] As the (D) amine compound, a polyfunctional amine compound having two or more primary to tertiary amino groups is preferably used. Specific examples of the (D) amine compound include ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, phenylenediamine, metaxylenediamine, diethylenetriamine, triethylenetetramine, triaminopropane, and amino group-containing resins having amino groups, such as polyvinylamine, polyethyleneimine, polyallylamine, and polylysine.

[0143] The number average molecular weight of the amino group-containing resin is, for example, 100 to 1,000,000, preferably 200 to 10,000, and more preferably 300 to 5,000. The number average molecular weight of the amino group-containing resin is determined, for example, by a known viscosity method. If the molecular weight of the amino group-containing resin is too large, the viscosity may become too high due to gel crosslinking in the adhesive composition liquid, which may cause problems in workability.

[0144] Among these, polyethyleneimine, an amino group-containing resin, can be suitably used as the amine compound (D) in the present invention. Polyethyleneimine is a water-soluble polymer obtained by polymerizing ethyleneimine, and is a polymer consisting of repeating units of amine and ethylene (CH2CH2). Polyethyleneimine generally contains primary, secondary, and tertiary amino groups, and for example, polyethyleneimine having a branched structure rather than a completely linear molecule and an average molecular weight of approximately 600 as a commercially available reagent can be used.

[0145] In the adhesive composition for organic fibers of the present invention, polyethyleneimine, which is the amine compound (D), interacts with the acetoacetyl groups of the acetoacetyl-modified polyvinyl alcohol (B), which is emulsified by the action of an emulsifier, on the surface of rubber latex dispersed in an aqueous solvent, thereby strengthening the protective film on the latex surface and suppressing the tackiness of the rubber latex. This makes it possible to suppress adhesion of the adhesive composition to rolls and the like in the process of coating an organic fiber cord with the adhesive composition and drying / thermally curing it, thereby improving workability.

[0146] The polyethyleneimine used in the present invention is available in liquid form, but when used in the adhesive composition of the present invention, it is preferably used as an aqueous solution.

[0147] The content (solid content) of the amine compound (D) relative to the total solid content of the adhesive composition for organic fibers of the present invention is not particularly limited, but is preferably 0.3% by mass or more, more preferably 1.0% by mass or more, and is preferably 35% by mass or less, more preferably 25% by mass or less.

[0148] <(E) Polyphenols> One preferred embodiment of the adhesive composition for organic fibers of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) an acetoacetyl group-modified polyvinyl alcohol, and (E) a polyphenol.

[0149] The (E) polyphenol is preferably a plant-derived compound having multiple phenolic hydroxy groups in the molecule. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition is improved. Specific examples of the (E) polyphenol include lignin, tannin, tannic acid, flavonoids, and derivatives thereof. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition is improved.

[0150] Research has long been conducted into the production of adhesives by separating polyphenols such as lignin and tannin, which are components of wood and bark, and reacting them with formaldehyde (see, for example, Japanese Patent Application Laid-Open No. 07-53858), but there is little knowledge about producing aqueous adhesive compositions that do not contain resorcinol.

[0151] The polyphenol (E) is preferably lignin or a derivative thereof. Lignin, together with polysaccharides such as cellulose, is a major component of plant cell walls. Lignin contains functional groups such as hydroxyl, methoxy, carbonyl, and carboxyl groups, and the phenolic hydroxyl groups in particular are highly reactive and can interact with cationic polymers such as polyethyleneimine.

[0152] Lignin is a polymer with a structure based on phenylpropane, but the molecular structure of lignin is diverse and it is a huge biopolymer that forms a three-dimensional network structure, so its molecular structure has not yet been fully elucidated.

[0153] Because native lignin forms a tightly packed composite with polysaccharides such as cellulose in plant cell walls, its isolation without denaturing its chemical structure is considered extremely difficult. Various industrial separation methods are used to extract lignin from wood and other materials. The lignins obtained after separation include sulfonate lignin, kraft lignin, soda lignin, and steam-exploded lignin. Among these industrially used lignins, the most well-known, from the standpoints of availability and economy, are those obtained on a large scale from the waste liquor of chemical pulping in the paper pulp manufacturing process, i.e., lignosulfonate or kraft lignin.

[0154] Other examples of lignins include lignins modified by hydroxymethylation, epoxidation, denitrification, acylation, or hydroxylation, diethanolamine-modified lignin, enzyme-modified lignin, laccase-modified lignin, urea-modified lignin, lignosulfonate, Alcel process lignin, alkali granite process lignin, polyethylene glycol-added lignin, and the like.

[0155] Kraft lignin is derived from a chemical pulping process known as kraft cooking, a high-temperature, high-pressure reaction in which wood chips, such as hardwood, softwood, miscellaneous wood, bamboo, kenaf, and bagasse, are introduced into a digester together with a cooking liquor containing sodium hydroxide and sodium sulfide. Acid and / or carbon dioxide are added to the kraft cooking waste liquor obtained after kraft cooking to precipitate the dissolved modified lignin, and the resulting precipitate is then dehydrated and washed to obtain kraft lignin. The dehydrated and washed precipitate can then be dissolved by adding an organic solvent such as alcohol or acetone, followed by separation of insoluble impurities and drying for purification, or by modification by introducing various functional groups as needed. Commercially available kraft lignin can be used. Among these, the reagent "Lignin, Alkali, Kraft" (CAS Number: 8068-05-1) manufactured by Sigma-Aldrich Co., LLC is preferred.

[0156] The sulfonated lignins are lignin sulfonic acids and their salts obtained using waste liquor eluted from sulfite pulp as a raw material in a sulfite cooking chemical pulping process in which wood chips are reacted with a cooking liquor containing sulfite and / or a sulfite salt at high temperature and high pressure. Particularly preferred examples include calcium lignin sulfonate, sodium lignin sulfonate, potassium lignin sulfonate, and magnesium lignin sulfonate. Among these, sodium lignin sulfonate is preferred. These sulfonated lignins are commercially available. For example, the Sunex series of lignin sulfonates manufactured by Nippon Paper Industries Co., Ltd. can be used as lignin sulfonates or modified lignin sulfonates.

[0157] Examples of high-value-added lignin sulfonates include not only high-purity products but also partially (low-) desulfonated lignin sulfonates, which have a reduced degree of sulfonation, obtained by heating lignin sulfonates in an alkaline aqueous solution using sodium hydroxide or ammonia in the presence of an oxidizing agent such as oxygen (see, for example, JP 2016-135834 A). Examples of high-purity lignin sulfonates or modified lignin sulfonates include the Pearlex series manufactured by Nippon Paper Industries Co., Ltd., and examples of partially desulfonated lignin sulfonates include the Vanilex series manufactured by Nippon Paper Industries Co., Ltd. Among these, the reagent "Lignin (Alkali)" (CAS Number: 8061-51-6, solid powder), manufactured by Tokyo Chemical Industry Co., Ltd., is preferred, as it is a partially (low-) desulfonated lignin sulfonate with a reduced degree of sulfonation.

[0158] Tannins are a group of polyphenolic compounds found in a wide range of plants, including woody trees, as well as fruits, leaves, and seeds, such as grapes, persimmons, berries, cloves, legumes, medicinal herbs, tea leaves, and cocoa beans. Tannin molecules generally contain numerous hydroxyl groups, and often also carboxyl groups, and tend to form strong complexes and conjugates with a wide range of macromolecules.

[0159] The tannins include tannic acid, proanthocyanidins, flavonoids, gallic acid esters, catechins, etc., as well as their derivatives such as salts and modified forms. Furthermore, the flavonoids are ubiquitous in the leaves, stems, and bark of plants, and are generally called tannins. These tannins consist of hydrolyzable tannins and condensed tannins. These tannins can be distinguished by boiling them in dilute hydrochloric acid; condensed tannins form insoluble precipitates, while hydrolyzable tannins hydrolyze to produce water-soluble substances.

[0160] Both hydrolyzable tannins and condensed tannins are water-soluble and can be extracted from plant materials such as wood, bark, leaves, fruits, pods, and insect larvae using methods such as hot water extraction. Hydrolyzable tannins can be obtained, for example, from chestnut and nut wood, oak bark, tea leaves, and oak gallnut and gallnut insect larvae. Condensed tannins can be obtained from quebracho wood, mimosa bark, persimmons, and buckwheat seeds. Among these, preferred hydrolyzable tannins include tannic acid obtained from oak gallnut and the like, available from Nakarai Tesque, Inc. under the reagent name "Tannic Acid" (CAS Number: 1401-55-4-6, solid powder), and condensed tannins obtained from mimosa bark, available from Kawamura Tsusho Co., Ltd. under the trade name "Mimosa" (solid powder).

[0161] The content (solids content) of the (E) polyphenol relative to the total solids in the adhesive composition for organic fibers of the present invention is not particularly limited, but is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more. The content of the (E) polyphenol is preferably 75% by mass or less, more preferably 50% by mass or less, and even more preferably 35% by mass or less. A content of the (E) polyphenol of 2% by mass or more improves the adhesion between the organic fiber and the coating rubber composition. A content of the (E) polyphenol of 75% by mass or less ensures that the amount of other components, such as rubber latex, blended into the adhesive composition for organic fibers is at a certain level or more, resulting in better adhesion to the rubber coating.

[0162] <Method of manufacturing adhesive composition for organic fibers> The adhesive composition for organic fibers of the present invention contains, as essential components, (A) a rubber latex having an unsaturated diene and (B) an acetoacetyl group-modified polyvinyl alcohol, and more preferably, contains one or more compounds selected from the group consisting of (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) an amine compound, and (E) a polyphenol.

[0163] In producing the adhesive composition for organic fibers, the (A) rubber latex having an unsaturated diene and the (B) acetoacetyl group-modified polyvinyl alcohol are mixed, and then the (C) aqueous compound having a (thermally dissociable blocked) isocyanate group, the (D) amine compound, and the (E) polyphenol can be mixed in any order.

[0164] In the adhesive composition for organic fibers of the present invention, the mixing mass ratio [(A):(B)] (solid content equivalent) of (A) the rubber latex having an unsaturated diene and (B) the acetoacetyl group-modified polyvinyl alcohol is not particularly limited, but is preferably in the range of 100:0.1 to 100:25, and more preferably in the range of 100:0.2 to 100:15.

[0165] When the mixing mass ratio is 100:0.1 or more (when the ratio is 1,000 or less), a coating of microcapsules of (B) acetoacetyl-modified polyvinyl alcohol can be formed around the (A) unsaturated diene-containing rubber latex as a core, and an adhesive layer of sufficient strength can also be obtained. Also, when the mixing mass ratio is 100:25 or less (when the ratio is 4 or more), the coating of microcapsules of (B) acetoacetyl-modified polyvinyl alcohol formed around the (A) unsaturated diene-containing rubber latex as a core does not become too thick, and when the coated rubber composition as an adherend for organic fibers and the adhesive composition for organic fibers are co-vulcanized to bond them, the coated rubber composition as an adherend and the (A) unsaturated diene-containing rubber latex are well miscible, and as a result, the initial process of adhesion between the coated rubber composition as an adherend and the adhesive composition for organic fibers proceeds smoothly.

[0166] When mixing the (A) rubber latex containing an unsaturated diene with the (B) acetoacetyl-modified polyvinyl alcohol, a known water-soluble material capable of strengthening the film formed from the (B) acetoacetyl-modified polyvinyl alcohol can be used in combination with the rubber latex. Examples of such materials include gum arabic, carrageenan, CMCs, and organic or inorganic salt electrolytes, such as cationic salts like sodium chloride, potassium chloride, magnesium chloride, and ammonium chloride, and anionic salts like sulfates, phosphates, carbonates, and acetates. Furthermore, water-soluble liquids in which the film-forming material dissolves less than in water, such as alcohols like ethanol and propanol, or water-soluble polymers like isobutylene-maleic anhydride ring-opening copolymer salts, can also be used.

[0167] In the adhesive composition for organic fibers of the present invention, the mixing mass ratio [(A):[(C)+(D)+(E)]] (solid content equivalent) of (A) the rubber latex having an unsaturated diene to (C) the aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) an amine compound, and (E) a compound selected from the group consisting of polyphenols is not particularly limited, but is preferably in the range of 100:5 to 100:300, more preferably in the range of 100:10 to 100:150, and even more preferably in the range of 100:15 to 100:60.

[0168] When the mixing mass ratio is 100:5 or more (20 or less in terms of the ratio), the proportion of the rubber latex having an unsaturated diene (A) in the adhesive composition for organic fibers is not too high, allowing the adhesive layer formed by the adhesive composition for organic fibers to maintain sufficient fracture resistance and prevent a decrease in adhesion under strain. When the mixing mass ratio is 100:300 or less (1 / 3 or more in terms of the ratio), the proportion of the rubber latex having an unsaturated diene (A) in the adhesive composition for organic fibers is not too low, allowing the coated rubber composition as an adherend for organic fibers and the adhesive composition for organic fibers to be co-vulcanized and bonded together, resulting in a sufficiently high adhesion between the coated rubber composition as an adherend and the adhesive composition for organic fibers.

[0169] Furthermore, the (A) rubber latex having an unsaturated diene, (B) acetoacetyl group-modified polyvinyl alcohol, (C) aqueous compound having a (thermally dissociable blocked) isocyanate group, (D) amine compound, and (E) polyphenol are preferably aqueous, since water, which is less polluting to the environment, can be used as a solvent.

[0170] [Organic fiber materials] The adhesive composition for organic fibers constructed as described above is applied to the surface of organic fibers, for example, organic fibers made of polyester resin, aromatic polyamide resin, acrylic resin, or the like, and then subjected to an appropriate heat treatment, whereby an adhesive layer made of the adhesive composition for organic fibers is applied to the surface of the organic fibers, thereby producing an adhesive-treated organic fiber material.

[0171] The organic fiber material of the present invention is characterized in that the surface of the organic fiber is coated with an adhesive layer made of the organic fiber adhesive composition. This allows the organic fiber material to be excellent in durability while ensuring environmental friendliness and workability. It is particularly preferred that the organic fiber be made of polyester resin, aromatic polyamide resin, or acrylic resin, and of these, polyester resin is preferred. Furthermore, it is also preferred that the organic fiber be a cord made of multiple twisted filaments.

[0172] Methods for coating the surface of organic fibers with an adhesive composition include immersing the organic fibers in the adhesive composition, applying the adhesive composition to the organic fibers with a brush, spraying the adhesive composition onto the organic fibers, and the like, and an appropriate method can be selected as needed. The method for coating the surface of organic fibers with the adhesive composition is not particularly limited, but when coating the surface of organic fibers with the adhesive composition, it is preferable to dissolve the adhesive composition in various solvents to reduce the viscosity, as this facilitates coating. Furthermore, it is environmentally preferable for the solvent for reducing the viscosity of the adhesive composition to consist mainly of water.

[0173] Furthermore, the solution concentration of the adhesive composition to be impregnated into the organic fibers is not particularly limited, but is preferably 5.0 mass % or more and 25.0 mass % or less, and more preferably 7.5 mass % or more and 20.0 mass % or less, in terms of solid content, relative to the mass of the organic fibers.

[0174] Here, the thickness of the adhesive layer made of the adhesive composition is not particularly limited, but is preferably 50 μm or less, and more preferably 0.5 μm or more and 30 μm or less.

[0175] In particular, when the organic fiber material of the present invention is applied to a tire, if the amount of adhesive composition deposited by the adhesive treatment increases, the adhesive durability under tire rolling tends to decrease. The reason for this is that the adhesive composition at the interface of the fiber material to be adhered has a high rigidity, so it bears the stress caused by strain and undergoes relatively little deformation, but the deformation due to strain increases with increasing distance from the interface. Since the adhesive composition contains a higher amount of thermosetting condensate than the adherend rubber material, it is hard and brittle, and therefore prone to adhesive fatigue under repeated strain. For these reasons, the average thickness of the adhesive composition layer is preferably 50 μm or less, and more preferably 0.5 μm or more and 30 μm or less.

[0176] When the organic fiber is a cord, the adhesive layer preferably has a dry mass of 0.5 to 6.0% by mass of the cord in the organic fiber material. By setting the dry mass of the adhesive layer within this range, appropriate adhesiveness can be ensured.

[0177] The organic fiber material, in which the surface of the organic fiber is coated with the organic fiber adhesive composition, is dried, for example, at a temperature of 100°C to 210°C, and then subsequently heat-treated. This heat treatment is preferably carried out at a temperature above the glass transition temperature of the polymer in the organic fiber, preferably at a temperature above the melting temperature of the polymer minus 70°C and below the melting temperature minus 10°C. The reason for this is that below the glass transition temperature of the polymer, the molecular mobility of the polymer is poor, and the adhesion-promoting components of the organic fiber adhesive composition do not interact sufficiently with the polymer, resulting in insufficient bonding strength between the organic fiber adhesive composition and the organic fiber. Such organic fibers may be pretreated in advance with electron beams, microwaves, corona discharge, plasma treatment, or the like.

[0178] [Rubber goods] The adhesive composition for organic fibers of the present invention can be suitably used for reinforcing various rubber articles. The rubber article of the present invention is characterized by being reinforced with the above-mentioned organic fiber material. This allows the rubber article to be excellent in durability while ensuring environmental friendliness and workability. Examples of such rubber articles of the present invention include tires, as well as conveyor belts, belts, hoses, air springs, etc.

[0179] [Organic fiber-rubber composite] The organic fiber-rubber composite of the present invention is a composite of organic fiber and rubber, characterized in that the organic fiber is coated with the above-mentioned adhesive composition for organic fiber. This makes it possible to obtain good adhesion without using resorcinol, and to obtain an organic fiber-rubber composite with good environmental friendliness and workability. The adhesive composition for organic fiber of the present invention is particularly excellent in adhesion between organic fibers such as organic fiber cords and the coated rubber composition.

[0180] The organic fiber-rubber composite of the present invention will be described in detail with reference to FIG.

[0181] Fig. 2 is a schematic cross-sectional view showing an organic fiber cord-rubber composite, which is an example of the organic fiber-rubber composite of the present invention. In the organic fiber-rubber composite 31 shown in Fig. 2, the outer surface in the outer diameter direction of an organic fiber cord 1 is coated with an adhesive layer 32 made of the organic fiber adhesive composition 2 of the present invention. The organic fiber cord 1 is then bonded to a coating rubber composition 33 located further outward in the outer diameter direction via the adhesive 32 made of the organic fiber adhesive composition 2, thereby forming the organic fiber-rubber composite 31 of the present invention.

[0182] The reinforcing material for rubber articles using the adhesive composition for organic fibers of the present invention can be in the form of short fibers, nonwoven fabrics, etc., in addition to the above organic fiber cord-rubber composite.

[0183] <Organic fiber cord> An organic fiber cord, which is an example of the organic fiber, is used to supplement the strength of rubber articles such as tires. When using the organic fiber cord as a reinforcing material, first, spun organic fiber raw yarn is twisted to form an organic fiber cord. Then, the organic fiber cord is embedded in rubber that coats the organic fiber cord using an organic fiber adhesive composition, and the organic fiber cord is bonded by vulcanization to produce an organic fiber-rubber composite. This organic fiber-rubber composite can be used as a reinforcing member for rubber articles such as tires.

[0184] The material of the organic fiber is not particularly limited, but examples thereof include fibrous materials such as polyester, aliphatic polyamide fibers such as 6-nylon, 6,6-nylon, and 4,6-nylon, protein fibers such as artificial fibroin fibers, polyketone fibers, aromatic polyamide fibers such as polynonamethylene terephthalamide and paraphenylene terephthalamide, acrylic fibers, carbon fibers, and cellulose fibers such as rayon and lyocell. Among these, polyester, 6-nylon, and 6,6-nylon are preferred, and polyester is particularly preferred.

[0185] The polyester material is a polymer having an ester bond in the main chain, more specifically, 80% or more of the bonding modes of the repeating units in the main chain are ester bonds. Examples of the polyester include, but are not limited to, those obtained by condensing glycols such as ethylene glycol, propylene glycol, butylene glycol, methoxypolyethylene glycol, and pentaerythritol with dicarboxylic acids such as terephthalic acid, isophthalic acid, and their dimethyl derivatives through an esterification reaction or transesterification reaction. The most typical polyester is polyethylene terephthalate.

[0186] The organic fiber cord is preferably an organic fiber cord formed by twisting together a plurality of monofilament filaments, particularly for the purpose of reinforcing rubber articles such as tires and conveyor belts. The organic fiber cord is also preferably an organic fiber cord formed by twisting together a top-twisted monofilament filament and a bottom-twisted monofilament filament. In this case, it is more preferable that the twist coefficient of the bottom twist be 1,300 or more and 2,500 or less, and / or the twist coefficient of the top twist be 900 or more and 1,800 or less.

[0187] In the present invention, the organic fiber is preferably a tire cord made of polyester (polyethylene terephthalate) with a twist structure of 1670 dtex / 2, a top twist of 39 times / 10 cm, and a bottom twist of 39 times / 10 cm, and the adhesive composition is adhered to this tire cord to form an organic fiber-rubber composite.

[0188] <<Coating rubber composition for organic fiber-rubber composite>> The coating rubber composition constituting the organic fiber-rubber composite of the present invention is preferably a rubber component blended with various compounding agents commonly used in the rubber industry. The rubber component is not particularly limited, and examples include natural rubber, conjugated diene-based synthetic rubbers such as polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR), as well as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-diene copolymer rubber (EPDM), and polysiloxane rubber. Among these, natural rubber and conjugated diene-based synthetic rubber are preferred. These rubber components may be used alone or in combination.

[0189] <<Method of manufacturing organic fiber-rubber composites>> The organic fiber-rubber composite of the present invention can be produced by coating organic fibers such as organic fiber cords with the organic fiber adhesive composition of the present invention to form an adhesive layer, and then co-vulcanizing and bonding the (A) unsaturated diene-containing rubber latex in the organic fiber adhesive composition and the rubber component in the coating rubber composition that is the adherend of the organic fibers.

[0190] For the co-vulcanization of the rubber components in the coating rubber composition, organic vulcanizing agents such as sulfur, thiralium polysulfide compounds such as tetramethylthiralium disulfide and dipentamethylenethiralium tetrasulfide, 4,4-dithiomorpholine, p-quinonedioxime, p,p'-dibenzoquinonedioxime, and cyclic sulfur imides can be used. Of these, sulfur is preferred. Furthermore, the rubber components in the coating rubber composition can be appropriately blended with various additives commonly used in the rubber industry, such as fillers such as carbon black, silica, and aluminum hydroxide, vulcanization accelerators, antioxidants, and softeners.

[0191] Furthermore, it goes without saying that the adhesive composition for organic fibers of the present invention also provides an adhesive effect in an adhesion method in which a vulcanizing agent contained in an adherend made of a synthetic resin material such as organic fiber and / or an adherend made of a coated rubber composition migrates to the adhesive composition for organic fibers, and the organic fiber adhesive composition is crosslinked by the migrated vulcanizing agent.

[0192] [tire] The tire of the present invention uses the organic fiber-rubber composite of the present invention, which allows for good adhesion without using resorcinol, and allows for a tire with good environmental friendliness and workability.

[0193] In the tire of the present invention, the organic fiber-rubber composite can be used as, for example, a carcass, a belt, a belt reinforcing layer, a reinforcing layer around the belt such as a flipper.

[0194] Depending on the type of tire to be applied, the tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization process or the like and then further vulcanizing it. The tire of the present invention uses organic fiber cords or the like treated with the adhesive composition for organic fibers at some location on the tire, but other components are not particularly limited and known components can be used. The tire of the present invention is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0195] The adhesive composition for organic fibers of the present invention, the organic fiber material using the same, and the organic fiber-rubber composite described above can be applied to all kinds of rubber articles, such as conveyor belts, belts, hoses, and air springs, in addition to the tires described above. [Example]

[0196] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0197] <(A-1) Synthetic rubber latex containing unsaturated diene> In the following Comparative Examples 1, 3 to 8, Examples 1 to 6, and Reference Examples 1 to 5, a vinylpyridine-styrene-butadiene copolymer latex was used as the synthetic rubber latex having an unsaturated diene (A-1) in accordance with Comparative Example 1 described in JP-A-9-78045, which was prepared as follows.

[0198] A 5-liter autoclave with a nitrogen atmosphere was charged with 130 parts by weight of deionized water and 4.0 parts by weight of potassium rosinate as an emulsifier and dissolved. A monomer mixture consisting of 15 parts by weight of vinylpyridine monomer, 15 parts by weight of styrene, and 70 parts by weight of butadiene, and 0.60 parts by weight of t-dodecyl mercaptan as a chain transfer agent, were then charged and emulsified. The mixture was then heated to 50°C, and 0.5 parts by weight of potassium persulfate as a polymerization initiator was added to initiate polymerization. After the monomer mixture reached a reaction rate of 90%, 0.1 parts by weight of hydroquinone was added to terminate the polymerization. Next, unreacted monomer was removed under reduced pressure, yielding a vinylpyridine-styrene-butadiene copolymer latex with a solids concentration of 41% by weight.

[0199] <(A-2) Natural rubber latex> In the following Comparative Example 2 and Example 7, a field latex having a solid content concentration of 60% was used as the (A-2) natural rubber latex after adjusting the solid content concentration to 41% with deionized water.

[0200] <(B) Acetoacetyl group-modified polyvinyl alcohol> In the following Examples 1 to 7 and Reference Examples 1 to 5, (B) acetoacetyl group-modified polyvinyl alcohol was (B-1) Mitsubishi Chemical Corporation's trade name "Gohsenex Z-200" (solids concentration 10%, saponification degree 99 mol% or more, aqueous solution), (B-2) Mitsubishi Chemical Corporation's trade name "Gohsenex Z-300" (solids concentration 10%, saponification degree 98 to 99 mol%, aqueous solution), or (B-3) Mitsubishi Chemical Corporation's trade name "Gohsenex Z-410" (solids concentration 10%, saponification degree 97.5 to 99.5%, aqueous solution), which was diluted with deionized water by the following method to obtain a 5% aqueous solution.

[0201] First, 50.0 g of the acetoacetyl-modified polyvinyl alcohol (B-1) to (B-3) described above was gradually added to 950.0 g of deionized water stirred at room temperature. After stirring this solution at room temperature for 10 minutes, it was heated to an internal temperature of 85 to 90°C and continued stirring at that temperature for 2 hours. After confirming dissolution of the acetoacetyl-modified polyvinyl alcohol, the acetoacetyl-modified polyvinyl alcohol aqueous solution was cooled to room temperature. The dissolved polyvinyl alcohol aqueous solution was then filtered through a 1 μm filter, and deionized water was added to replace the water that evaporated during heating and stirring, producing an acetoacetyl-modified polyvinyl alcohol aqueous solution with a solids concentration of 5% by mass. This aqueous solution was used to prepare the adhesive composition.

[0202] <(C) Aqueous Compound Having a (Thermally Dissociable Blocked) Isocyanate Group> In the following Comparative Example 3 and Example 6, Grillbond IL-6 (solid content concentration: 50% by mass), a product of EMS-CHEMIE HOLDIMG AG, which is a blocked compound of caprolactam with methylene diphenyl diisocyanate (C-1), was used as is as the aqueous compound having a (thermally dissociable blocked) isocyanate group (C).

[0203] In the following Comparative Example 4 and Examples 1 to 5 and 7, the trade name "Elastron BN77" (aqueous urethane compound having a (C-2) (thermally dissociable blocked) isocyanate group, blocking agent thermal dissociation temperature: approximately 160°C, pH: 8.0, solid content concentration: 31% by mass) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. was used as is as the aqueous compound having a (thermally dissociable blocked) isocyanate group (C).

[0204] <(D) Amine Compound> In the following Comparative Example 5 and Reference Example 2, the (D) amine compound was a reagent named "polyethyleneimine (average molecular weight approximately 600)" (CAS number: 9002-98-6, liquid) manufactured by Wako Pure Chemical Industries, Ltd., diluted with deionized water to prepare an aqueous solution with a solids concentration of 10 mass %, and this aqueous solution was used to prepare the adhesive composition.

[0205] <(E) Polyphenols> In the following Comparative Examples 6 to 8, Example 4, and Reference Examples 3 to 5, the (E) polyphenol used was one in which the polyphenol was kraft lignin (E-1), one in which the polyphenol was lignin sulfonate (E-2), and one in which the polyphenol was condensed tannin (E-3), as shown below. These powdered polyphenols were dissolved in deionized water to prepare aqueous solutions with a solids concentration of 5% by mass, and these aqueous solutions were used to prepare adhesive compositions.

[0206] (E-1) Kraft lignin, product name "Lignin, alkali" (CAS Number: 8068-05-1), manufactured by Sigma-Aldrich Co. LLC (E-2) "Lignin (alkali)" (CAS Number: 8061-51-6), a trade name manufactured by Tokyo Chemical Industry Co., Ltd., partially desulfonated lignosulfonate with reduced sulfonation degree (E-3) Kawamura Tsusho Co., Ltd., product name "Mimosa" (solid powder) tannin

[0207] <<Preparation of Latex Adhesive Compositions (Comparative Examples 1 and 2)>> The rubber latex (A) and water were blended (wet blending) as shown in Table 2, and the amounts were adjusted to give a solids concentration of 17% by mass. The mixture was then thoroughly stirred to obtain a latex adhesive composition. In the following Comparative Example 1, the synthetic rubber latex having an unsaturated diene (A-1) was used, and in Comparative Example 2, the natural rubber latex (A-2) was used.

[0208] <<Preparation of Latex-Waterborne Urethane Adhesive Compositions (Comparative Examples 3 and 4)>> The synthetic rubber latex having an unsaturated diene (A-1) and the aqueous compound having a (thermally dissociable blocked) isocyanate group (C-1) were blended (wet blending) as shown in Table 2, and the amount of water was adjusted to give a solids concentration of the adhesive composition of 17 mass %, followed by mixing and thorough stirring to obtain a latex-aqueous urethane adhesive composition (Comparative Example 3).

[0209] Furthermore, the synthetic rubber latex having an unsaturated diene (A-1) and the aqueous compound having a (thermally dissociable blocked) isocyanate group (C-2) were blended (wet blending) as shown in Table 2, and the amount of water was adjusted to give a solids concentration of the adhesive composition of 17 mass %, followed by mixing and thorough stirring to obtain a latex-aqueous urethane adhesive composition (Comparative Example 4).

[0210] <<Preparation of Latex-Amine Compound Adhesive Composition (Comparative Example 5)>> The above (A-1) synthetic rubber latex having an unsaturated diene and the above (D) amine compound were blended (wet blending) as shown in Table 2, and the amount of water was adjusted to give a solids concentration of the adhesive composition of 17 mass %, followed by mixing and thorough stirring to obtain a latex-amine compound adhesive composition (Comparative Example 5).

[0211] <<Preparation of Latex-Polyphenol Adhesive Compositions (Comparative Examples 6 to 8)>> The above (A-1) synthetic rubber latex having an unsaturated diene and the above (E) polyphenol were blended (wet blending) as shown in Table 3, and the amount of water was adjusted to make the solid content concentration of the adhesive composition 17 mass %, and then the mixture was mixed and thoroughly stirred to obtain latex-polyphenol adhesive compositions (Comparative Examples 6 to 8).

[0212] <<Preparation of Adhesive Compositions (Examples 1 to 7, Reference Examples 1 to 5) According to an Embodiment of the Invention>> As shown in Tables 3 to 5, each of the specified (A) rubber latex having an unsaturated diene, (B) acetoacetyl group-modified polyvinyl alcohol, (C) aqueous compound having a (thermally dissociable blocked) isocyanate group (Examples 1 to 7), (D) amine compound (Reference Example 2), and (E) polyphenol (Example 4, Reference Examples 3 to 5) was blended (wet blended) in this order, and the amount of water was adjusted to give a solids concentration of the adhesive composition of 17 mass %, followed by mixing and thorough stirring to obtain adhesive compositions (Examples 1 to 7, Reference Examples 1 to 5) according to one embodiment of the present invention.

[0213] <Coating of tire cord with each adhesive composition> As the organic fiber cord, a tire cord made of polyethylene terephthalate with a twist structure of 1670 dtex / 2, a top twist number of 39 times / 10 cm, and a bottom twist number of 39 times / 10 cm was used.

[0214] The tire cord was immersed in each of the adhesive compositions of Comparative Examples 1 to 8, Examples 1 to 7, and Reference Examples 1 to 5 so that the concentration of the adhesive composition impregnated into the tire cord was 3.8 mass % relative to the mass of the organic fiber cord. The tire cord was then sequentially dried in a drying zone (150°C, 60 seconds), thermally cured in a hot zone while applying tension (0.8 kg / cord), and thermally cured in a normalization zone while releasing the tension (240°C, 60 seconds), thereby obtaining tire cords coated with each of the adhesive compositions of Comparative Examples 1 to 8, Examples 1 to 7, and Reference Examples 1 to 5.

[0215] <Production of tire cord-rubber composite> Tire cords coated with the adhesive compositions of Comparative Examples 1 to 8, Examples 1 to 7, and Reference Examples 1 to 5 were embedded in an unvulcanized rubber composition and co-vulcanized at 155°C for 20 minutes. The unvulcanized rubber composition used for coating was a rubber composition containing natural rubber, styrene-butadiene rubber, carbon black, vulcanization chemicals, etc.

[0216] <Evaluation of workability of adhesive composition> The adhesive compositions of the comparative examples and examples were evaluated for workability as follows.

[0217] <<Evaluation of mechanical stability (solidification rate)>> The mechanical stability (coagulation rate) of each adhesive composition was measured in accordance with the method specified in JIS K6392-1995 using a Maron mechanical stability tester for copolymer latex compositions (Maron Stability Tester No. 2312-II, manufactured by Kumagai Riki Kogyo Co., Ltd.).

[0218] In summary, each adhesive composition was subjected to shear strain for 10 minutes using the rotor of the Maron mechanical stability tester at a compression load of 10 kg and a rotation speed of 1000 r / min, and then the solidification rate (%) was evaluated using the following formula from the amount of solidified material that was generated, and rounded to one decimal place. A smaller value indicates better mechanical stability. Coagulation rate (%) = [(dry mass of coagulated material) / (mass of solid content of test adhesive liquid)] × 100

[0219] <<Evaluation of adhesion to squeeze rolls>> The polyethylene terephthalate tire cord, which is an organic fiber cord, was continuously treated for 2000 m in a dipping treatment machine storing each adhesive composition, and the amount of each adhesive composition adhering to the squeeze roll was visually observed and evaluated on the following 5-point scale. Extra large: Especially large. Large: Many. Medium: Moderate. Few: Few. Minor: Very little.

[0220] <Evaluation of Adhesion Properties of Adhesive Compositions> The adhesive properties of the adhesive compositions of the comparative examples and examples were evaluated as follows.

[0221] <<Evaluation of adhesive strength>> The tire cord-rubber composite obtained using each adhesive composition was pulled at a speed of 300 mm / min to peel the tire cord from the tire cord-rubber composite, and the peel resistance per tire cord was determined, which was taken as the adhesive strength (N / cord).

[0222] <<Evaluation of the adhesion state of coated rubber>> The tire cord peeled from the tire cord-rubber composite was visually observed for the state of adhesion of the coating rubber, and was scored according to Table 1 below.

[0223] [Table 1]

[0224] <Results of workability evaluation and adhesion evaluation of adhesive compositions> The formulations of the adhesive compositions of the comparative examples and examples are shown in Tables 2 to 5 below, and the results of the workability evaluation and adhesiveness evaluation are shown in Table 6 below.

[0225] [Table 2]

[0226] [Table 3]

[0227] [Table 4]

[0228] [Table 5]

[0229] *A-1) Vinylpyridine latex: Vinylpyridine-styrene-butadiene copolymer latex (solid content concentration 41% by mass) synthesized by the above method *A-2) Natural rubber latex: Field latex (solid concentration 41%) *B-1) Acetoacetyl-modified polyvinyl alcohol: Mitsubishi Chemical Corporation, product name "Gohsenex Z-200" (purity 93.5% or more, powder), saponification degree 99% or more, viscosity of 4% aqueous solution at 20°C 11.5 to 14.0 mPa·s (catalog value) *B-2) Acetoacetyl-modified polyvinyl alcohol: Mitsubishi Chemical Corporation, product name "Gohsenex Z-300" (purity 93.5% or more, powder), saponification degree 98-99%, viscosity of 4% aqueous solution at 20°C 24.0-30.0 mPa·s (catalog value) *B-3) Acetoacetyl-modified polyvinyl alcohol: Mitsubishi Chemical Corporation, product name "Gohsenex Z-410" (purity 93.5% or more, powder), saponification degree 97.5-99.5%, viscosity of 4% aqueous solution at 20°C 43.5-58.5 mPa·s (catalog value) *C-1) Aqueous compound having a (thermally dissociable blocked) isocyanate group: EMS-CHEMIE HOLDIMG AG, product name "GRILLBOND IL-6" (solid content concentration 50% by mass), a blocked compound of methylene diphenyl diisocyanate and caprolactam *C-2) Aqueous compound having a (thermally dissociable blocked) isocyanate group: Daiichi Kogyo Seiyaku Co., Ltd., product name "Elastron BN77" (blocking agent thermal dissociation temperature: approximately 160°C, pH 8.0, solid content concentration 31% by mass) Aqueous urethane compound having a (thermally dissociable blocked) isocyanate group *D) Polyethyleneimine: manufactured by Wako Pure Chemical Industries, Ltd., reagent name "Polyethyleneimine average molecular weight 600" (solid concentration 100% by mass, liquid) *E-1) Polyphenol: Sigma-Aldrich Co. LLC, product name "Lignin,alkali" (CAS Number: 8068-05-1) Kraft lignin *E-2) Polyphenol: Partially desulfonated lignosulfonate with reduced sulfonation level, product name "Lignin (alkali)" (CAS Number: 8061-51-6), manufactured by Tokyo Chemical Industry Co., Ltd. *E-3) Polyphenol: Kawamura Tsusho Co., Ltd., product name "Mimosa" (solid powder) tannin

[0230] [Table 6]

[0231] Table 6 shows that when (B) acetoacetyl-modified polyvinyl alcohol is added to (A) rubber latex having an unsaturated diene, the antibacterial effect of the adhesive composition extends the usable period as an adhesive.

[0232] Furthermore, Table 6 shows that in each of the Examples and Reference Examples, adhesive compositions were obtained that had good workability and good adhesion between the organic fiber and the coating rubber composition. [Industrial Applicability]

[0233] According to the present invention, it is possible to provide an adhesive composition for organic fibers that can ensure desired adhesiveness without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires that use the same. Therefore, the present invention can be used in industrial fields that manufacture rubber articles such as tires. [Explanation of symbols]

[0234] 1: Organic fiber cord 2: Adhesive composition 3: Dipping bath 4: Organic fiber cord coated with adhesive composition 5: Squeeze roll 6: Drying zone 7: Hot Zone 8: Normalization Zone 31: Organic fiber-rubber composite 32: Adhesive layer made of adhesive composition 33: Coating rubber composition

Claims

1. An adhesive composition for organic fibers, comprising (A) a rubber latex having an unsaturated diene, (B) an acetoacetyl group-modified polyvinyl alcohol, and (C) an aqueous compound having a (thermally dissociable blocked) isocyanate group.

2. Furthermore, the following (D) and (E): (D) an amine compound, and (E) Polyphenols 2. The adhesive composition for organic fibers according to claim 1, which comprises one or more compounds selected from the group consisting of:

3. 3. The adhesive composition for organic fibers according to claim 1, wherein the saponification degree of the acetoacetyl group-modified polyvinyl alcohol (B) is 80 mol % or more.

4. 2. The adhesive composition for organic fibers according to claim 1, wherein the aqueous compound having a (thermally dissociable, blocked) isocyanate group (C) is a water-dispersible (thermally dissociable, blocked) isocyanate compound (C-1) composed of an addition product of a polyisocyanate having an aromatic ring and a blocking agent having one or more active hydrogen groups.

5. The adhesive composition for organic fibers according to claim 4, wherein the water-dispersible (thermally dissociable blocked) isocyanate compound (C-1) formed from an addition product of a polyisocyanate having an aromatic ring and a blocking agent having one or more active hydrogen groups is a blocked product of methylene diphenyl diisocyanate.

6. The adhesive composition for organic fibers according to claim 1, wherein the aqueous compound having a (thermally dissociable blocked) isocyanate group (C) is an aqueous urethane compound having a (thermally dissociable blocked) isocyanate group (C-2).

7. The aqueous urethane compound (C-2) having a (thermally dissociable blocked) isocyanate group is (α) an organic polyisocyanate compound having 3 or more and 5 or less functional groups and a number average molecular weight of 2,000 or less; (β) a compound having 2 or more and 4 or less active hydrogen groups and a number average molecular weight of 5,000 or less; (γ) a thermally dissociable blocking agent, and (δ) a compound having at least one active hydrogen group and at least one hydrophilic group which is anionic, cationic or nonionic; The mixing ratio of each of (α), (β), (γ) and (δ) to the total amount is (α) is 40% by mass or more and 85% by mass or less, (β) is 5% by mass or more and 35% by mass or less, (γ) is 5% by mass or more and 35% by mass or less, and (δ) is 5% by mass or more and 35% by mass or less, and reacting the mixture to give a reaction product, 7. The adhesive composition for organic fibers according to claim 6, wherein the constituent ratio of the (thermally dissociable blocked) isocyanate group in the reaction product is 0.5% by mass or more and 11% by mass or less, when the molecular weight of the isocyanate group (—NCO) is 42.

8. The aqueous urethane compound (C-2) having a (thermally dissociable blocked) isocyanate group is represented by the following general formula (1): [In formula (1), A is a residue of an organic polyisocyanate compound from which an active hydrogen group has been eliminated, X is a residue of a polyol compound having 2 or more and 4 or less hydroxyl groups and a number average molecular weight of 5,000 or less, from which an active hydrogen group has been eliminated; Y is a residue of the thermally dissociable blocking agent from which the active hydrogen group has been eliminated; Z is a residue of a compound having at least one active hydrogen group and at least one salt-forming group or a hydrophilic polyether chain, from which the active hydrogen group has been eliminated; n is an integer between 2 and 4, p + m is an integer between 2 and 4 (m≧0.25) The adhesive composition for organic fibers according to claim 6, wherein the organic fiber adhesive composition is

9. 3. The adhesive composition for organic fibers according to claim 2, wherein the amine compound (D) is a polyfunctional amine compound having two or more primary, secondary, or tertiary amino groups.

10. 3. The adhesive composition for organic fibers according to claim 2, wherein the polyphenol (E) is a plant-derived compound having a plurality of phenolic hydroxy groups in the molecule.

11. 3. The adhesive composition for organic fibers according to claim 2, wherein the polyphenol (E) is lignin, tannin, tannic acid, a flavonoid, or a derivative thereof.

12. The adhesive composition for organic fibers according to any one of claims 1 to 11, which does not contain resorcinol.

13. An organic fiber material, characterized in that the surface of an organic fiber is coated with an adhesive layer comprising the adhesive composition for organic fibers according to any one of claims 1 to 12.

14. 14. The organic fiber material according to claim 13, wherein the organic fiber is a cord formed by twisting together a plurality of filaments.

15. 15. The organic fiber material according to claim 14, wherein the cord has a first twist and a second twist, the first twist having a twist multiplier of 1,300 or more and 2,500 or less, and the second twist having a twist multiplier of 900 or more and 1,800 or less.

16. 16. The organic fiber material according to claim 14, wherein the adhesive layer has a dry mass of 0.5 to 6.0% by mass of the mass of the cord.

17. The organic fiber material according to any one of claims 13 to 16, wherein the organic fiber is made of a polyester resin.

18. A rubber article reinforced with the organic fiber material according to any one of claims 13 to 17.

19. An organic fiber-rubber composite, comprising an organic fiber and rubber, the organic fiber being coated with the adhesive composition for organic fibers according to any one of claims 1 to 12.

20. A tire using the organic fiber-rubber composite according to claim 19.

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