Adhesive compositions, organic fiber materials, rubber articles, organic fiber-rubber composites, and tires

Abstract

The present invention addresses the problem of providing an adhesive composition which can ensure desired adhesiveness without requiring the use of resorcin and does not reduce operation efficiency when used. The adhesive composition is characterized by including (A) a rubber latex having an unsaturated diene and (B) a polyvalent-metal salt and further containing at least one ingredient selected from the group consisting of (C) aqueous ingredients having a plurality of phenolic hydroxy groups in the molecule, (D) water-soluble ingredients having an amide bond structure, (E) amine compounds, and (F) poly(vinyl alcohol).

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an organic fiber material, a rubber article, an organic fiber-rubber composite, and a tire.

Background Art

[0002] Conventionally, for the purpose of reinforcing rubber articles such as tires, an organic fiber such as a tire cord made of nylon fiber, polyester fiber, etc. and a rubber composition such as a rubber composition for tires are adhered to form an organic fiber-rubber composite. And, for the adhesion, a method of coating an organic fiber with an adhesive composition, embedding it in a rubber composition, and co-vulcanizing it with the rubber composition is widely used.

[0003] Also, in the step of coating the organic fiber with the adhesive composition, a solvent is generally used for the purpose of adjusting the viscosity of the adhesive composition. However, since the solvent volatilizes in this step, it is preferable to use water with a low environmental load as the solvent. Further, when the organic fiber is coated with the adhesive composition by dipping, it is necessary to make the viscosity of the adhesive composition low enough to be applied by dipping.

[0004] Generally, components contained in an aqueous adhesive composition, that is, a water-based adhesive composition having the property of being soluble or dispersible in water, need to have a polar molecular structure. However, on the other hand, polymer materials such as rubber and organic fibers as adherends have low polarity, and when the difference between the polarity of the surface of rubber, organic fibers, etc. and the polarity of the components contained in the adhesive composition becomes large, it becomes difficult to adhere. Therefore, in order to use the water-based adhesive composition as an adhesive composition for rubber articles, the components contained in the water-based adhesive composition need to have polarity because they are water-based, but on the other hand, it is necessary to control the polarity so that there is no difference from the polarity of the adherend and the adhesiveness does not decrease. Therefore, a water-based adhesive composition having a function capable of reconciling these conflicting requirements is preferably used.

[0005] Here, regarding the process of coating the organic fibers with the adhesive composition, an example of the process when immersing an organic fiber cord, such as a tire cord, in the adhesive composition will be explained using Figure 1.

[0006] The organic fiber cord 1 is unwound from an unwinding roll, transported by the roll, and immersed in an immersion bath (dipping tank) 3 containing an adhesive composition 2. The organic fiber cord 4 coated with the adhesive composition 2 is lifted out of the immersion bath 3, and excess adhesive composition 2 is removed by a squeezing roll 5. Next, the organic fiber cord 4 coated with the adhesive composition 2 is further transported by the roll, dried in a drying zone 6, stretched by tension in a hot zone 7 while undergoing heat curing of the resin, and then in a normalizing zone 8 while undergoing heat curing of the resin while the tension is precisely adjusted to achieve the desired elongation properties. After being air-cooled outside the zone, it is wound onto a winding roll. In this way, the organic fiber is coated with the adhesive composition.

[0007] Conventionally, the adhesive compositions used have included RFL (resorcinol-formaldehyde-latex) adhesive compositions obtained by aging a mixture containing resorcinol, formaldehyde, and rubber latex, or adhesive compositions obtained by mixing a specific adhesion promoter with the RFL adhesive composition (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 a water-based phenolic resin obtained by mixing and aging water-soluble resorcinol and formaldehyde has been found to have the function of achieving both adhesion to the rubber to be adhered and adhesion to the surface of a substrate with low polarity, such as organic fibers, and is widely used worldwide. In adhesion using the above RFL adhesive composition, the rubber latex component adheres to the rubber side by co-vulcanization, while the phenolic resin component consisting of a condensate of resorcinol and formaldehyde, which has adhesive properties to organic fiber substrates, adheres to the substrate side.

[0009] The reason why resorcinol is preferred here is that it can provide a phenolic condensation resin, which is a resin species with high adhesion to the adherend, and the polar functional group introduced into the phenol ring to obtain water solubility is a hydroxyl group, which has relatively low polarity and is less likely to cause steric hindrance, thus providing a resin component with high adhesion to the organic fiber substrate.

[0010] Furthermore, the RFL adhesive composition is obtained by mixing resorcinol, formaldehyde, and rubber latex using rosinic acid or the like as an emulsifier during polymerization in the presence of a basic composition, and then aging the mixture. It is presumed that this causes the water-soluble resorcinol and formaldehyde to condense in a resol-type condensation reaction under basic conditions (see Patent Document 2), and that the rosinic acid on the latex surface undergoes addition condensation with the methylol group at the end of the resol-type phenol-formaldehyde addition condensate (see Non-Patent Document 1).

[0011] This maturation process crosslinks the latex with the resol-type resorcinol-formaldehyde condensate via rosinic acid, strengthening adhesion. The latex then combines with the aqueous resin to form a encapsulated protective colloid. When processing the adhesive composition in an apparatus like the one shown in Figure 1, the rubber tackiness of the latex is suppressed, resulting in less contamination of the apparatus by the adhesive composition.

[0012] Furthermore, as an adhesion promoter added to the RFL adhesive composition, water-based adhesive compositions have been used to improve adhesion to substrate surfaces with low polarity, such as organic fiber cords, by using water-based adhesive compositions. In this context, an adhesion promoter that is water-based, i.e., one that can be dissolved or dispersed in water, has been used.

[0013] Examples of water-dispersible adhesion promoters include (blocked) isocyanates such as methylenediphenyl diisocyanate with a particle size of 0.01 to 0.50 μm (see Patent Document 3), and water-dispersible particles of water-insoluble phenolic / novolac type resins such as cresol novolac type polyfunctional epoxy resins (see Patent Document 4).

[0014] Furthermore, as adhesion promoters containing water-soluble groups, phenolic resins that dissolve in water in the presence of basic substances such as a sodium hydroxide solution of a novolac-type condensate obtained by a novolac reaction between resorcinol and formaldehyde (see Patent Document 5), an ammonium solution of a novolac-type condensate of chlorophenols and formaldehyde, and aqueous urethane compounds having a (thermally dissociable blocked) isocyanate group and a self-water-soluble group (see Patent Document 6) have been proposed.

[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, from the perspective of reducing environmental impact.

[0016] To address this, various adhesive compositions using water as a solvent have been investigated and proposed, utilizing polyphenols that do not contain resorcinol.

[0017] For example, adhesive compositions consisting 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 and formaldehyde.

[0018] Furthermore, as an adhesive composition that does not contain resorcinol and formaldehyde, Patent Document 10 below discloses an aqueous adhesive composition containing a polyacrylamide-based water-soluble resin having a branched structure and at least one aqueous-based polymer selected from synthetic resin emulsions and rubber latexes. [Prior art documents] [Patent Documents]

[0019] [Patent Document 1] U.S. Patent No. 2128229 [Patent Document 2] Japanese Patent Publication No. 2005-263887

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Non-Patent Document

[0020]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0021] However, when an adhesive composition for organic fiber cords that does not contain resorcin as described above is used, the adhesiveness of the rubber latex measured as the mechanical stability under shear strain of the adhesive liquid becomes high. 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 FIG. 1, the adhesion of the adhesive composition 2 to the squeezing roll 5, the rolls in the drying zone 6, etc. increases, and a new problem occurs that the workability of this process deteriorates.

[0022] Furthermore, adhesive compositions that do not contain resorcinol and formaldehyde (so-called rubber glues) are prone to reduced adhesion because, without coating with a resorcinol-formaldehyde condensate, the tackiness of the rubber latex is not suppressed, and the surface of the adhesive coating becomes rough, especially when it adheres to the aforementioned device. Moreover, because crosslinking between the latex component and the resorcinol-formaldehyde condensate cannot be 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.

[0023] Furthermore, as described in Patent Document 7, when an aqueous adhesive composition is manufactured by mixing polyphenols mixed with rubber latex with aromatic dialdehydes such as terephthalaldehyde or 2,5-franjicarboxaldehyde, which have low solubility in water, the aromatic dialdehyde is difficult to dissolve in water during manufacturing, resulting in insufficient workability. Also, compared to resorcinol, which is soluble in water even without alkali addition, the preparation process of the adhesive composition liquid requires the addition of alkali to the phenolic groups of aromatic compounds, which have low water solubility, to make them soluble in water. As a result, the amount of base contained in the adhesive composition increases during subsequent vulcanization bonding with the adherend, and the vulcanization reaction of the contained rubber latex is generally accelerated, which has the problem of causing a decrease in adhesion due to over-vulcanization under prolonged heat.

[0024] Furthermore, adhesive compositions that do not contain resorcinol, as described above, also have the problem of causing a decrease in the cord strength of organic fiber cords coated with the adhesive composition.

[0025] Therefore, the object of the present invention is to provide an adhesive composition that can ensure desired adhesion without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires using the same. [Means for solving the problem]

[0026] In order to solve the above problems, the inventors diligently researched the composition of adhesive compositions and, as a result, discovered that by blending a polyvalent metal salt and a predetermined component together with a predetermined rubber latex, it is possible to obtain an adhesive composition that ensures the desired adhesion without using resorcinol, and that does not impair workability during use. This led to the completion of the present invention. In other words, the gist of the adhesive composition, organic fiber material, rubber article, organic fiber-rubber composite, and tire of the present invention is as follows.

[0027] [1] (A) Rubber latex having an unsaturated diene, (B) containing polyvalent metal salts, Furthermore, see (C)~(F): (C) Aqueous component having multiple phenolic hydroxyl groups in the molecule, (D) Water-soluble components containing an amide bond structure, (E) Amine compounds, (F) Polyvinyl alcohol An adhesive composition characterized by containing one or more components selected from the group consisting of the following.

[0028] [2] Furthermore, see (G)~(H): (G) Epoxide compound, Aqueous compounds having (H)(thermally dissociable blocked) isocyanate groups The adhesive composition according to [1], comprising one or more components selected from the group consisting of the following.

[0029] [3] The adhesive composition according to [1] or [2], wherein the (B) polyvalent metal salt is a salt of a metal ion with a valency of 2 or more.

[0030] [4] The adhesive composition according to any one of [1] to [3], wherein the (B) polyvalent metal salt is a metal salt that is water-soluble and forms a polyvalent metal ion with 4 or 6 coordination.

[0031] [5] The adhesive composition according to any one of [1] to [4], wherein the (B) polyvalent metal salt is a metal salt containing one or more metals selected from the group consisting of iron and copper.

[0032] [6] The adhesive composition according to any one of [1] to [5], wherein the aqueous component having a plurality of phenolic hydroxyl groups in the molecule (C) is a plant-derived component having a plurality of phenolic hydroxyl groups in the molecule.

[0033] [7] The adhesive composition according to [6], wherein the aqueous component having a plurality of phenolic hydroxyl groups in the (C) molecule is a polyphenol such as lignin, tannin, tannic acid, flavonoid, or a derivative thereof.

[0034] [8] The adhesive composition according to any one of [1] to [5], wherein the aqueous component having a plurality of phenolic hydroxyl groups in the molecule (C) is an aqueous compound comprising aromatic hydrocarbons having phenolic hydroxyl groups in the molecule and formaldehyde.

[0035] [9] The adhesive composition according to [8], wherein the aqueous component having a plurality of phenolic hydroxyl groups in the molecule (C) is an aqueous compound comprising a polycyclic aromatic hydrocarbon having a phenolic hydroxyl group in the molecule and formaldehyde.

[0036]

[10] The adhesive composition according to any one of [1] to [9], wherein the water-soluble component containing the (D) amide bond structure is a water-soluble component containing a peptide structure or a water-soluble compound containing an acrylamide structure.

[0037]

[11] The adhesive composition according to

[10] , wherein the water-soluble component containing the (D) amide bond structure is one or more water-soluble components selected from the group consisting of proteins and polypeptides obtained by hydrolyzing proteins.

[0038]

[12] The adhesive composition according to

[11] , wherein the water-soluble component containing the (D) amide bond structure is one or more proteins selected from the group consisting of casein and gelatin.

[0039]

[13] The adhesive composition according to

[11] , wherein the water-soluble component containing the (D) amide bond structure is a polypeptide obtained by hydrolyzing a protein derived from wool, milk, beans, silk, fish scales, or skin.

[0040]

[14] The adhesive composition according to

[10] , wherein the water-soluble component containing the (D) amide bond structure is an aqueous compound of polyacrylamide or a modified thereof.

[0041]

[15] The adhesive composition according to

[14] , wherein the water-soluble component containing the (D) amide bond structure is an amphoteric polyacrylamide.

[0042]

[16] The adhesive composition according to any one of [1] to

[15] , wherein the (E) amine compound is a polyfunctional amine compound having two or more primary to tertiary amino groups.

[0043]

[17] The adhesive composition according to any one of [1] to

[16] , wherein the (F) polyvinyl alcohol has a degree of saponification of 80 mol% or more.

[0044]

[18] The adhesive composition according to any one of [1] to

[17] , wherein the (F) polyvinyl alcohol is acetoacetyl-modified polyvinyl alcohol.

[0045]

[19] The adhesive composition according to any one of [2] to

[18] , wherein the (G) epoxide compound has two or more epoxy groups in one molecule.

[0046]

[20] The adhesive composition according to any one of [2] to

[19] , wherein the (G) epoxide compound is a reaction product of polyhydric alcohols and epichlorohydrin.

[0047]

[21] The adhesive composition according to any one of [2] to

[20] , wherein the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is a water-dispersible (thermally dissociable blocked) isocyanate compound comprising an addition product of a polyisocyanate having an (H-1) aromatic ring and a blocking agent having one or more active hydrogen groups.

[0048]

[22] The adhesive composition according to

[21] , wherein the water-dispersible (thermally dissociable blocked) isocyanate compound, which is an addition product of a polyisocyanate having an (H-1) aromatic ring and a blocking agent having one or more active hydrogen groups, is a blocked form of methylenediphenyl diisocyanate.

[0049]

[23] The adhesive composition according to any one of [2] to

[20] , wherein the aqueous compound having a (H)(thermally dissociable blocked) isocyanate group is an aqueous urethane compound having a (H-2)(thermally dissociable blocked) isocyanate group.

[0050]

[24] The aqueous urethane compound having the (H-2)(thermally dissociable blocked) isocyanate group, (α) Organic polyisocyanate compounds having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less. (β) Compounds 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 hydrophilic group that is anionic, cationic, or nonionic, The respective mixing ratios of (α), (β), (γ), and (δ) relative to the total amount are For (α), 40% by mass or more, 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, 35% by mass or less, and For (δ), 5% by mass or more, 35% by mass or less. The reaction product after mixing and reacting the ingredients in such a way, and The adhesive composition according to

[23] , wherein the molecular weight of the isocyanate group (-NCO) is 42, and the proportion of (thermally dissociable blocked) isocyanate groups in the reaction product is 0.5% by mass or more and 11% by mass or less.

[0051]

[25] The aqueous urethane compound having the (H-2)(thermally dissociable blocked) isocyanate group is the following general formula (1): [ka] [In formula (1), A is a residue from an organic polyisocyanate compound in which the active hydrogen group has been removed. X is a polyol compound having 2 to 4 hydroxyl groups and a number-average molecular weight of 5,000 or less, from which the active hydrogen group has been removed. Y is a residue from which the active hydrogen group has been removed from a thermally dissociable blocking agent. Z is a residue from which the active hydrogen group has been removed from a compound having at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain. n is an integer between 2 and 4, p+m is an integer between 2 and 4 (m≧0.25). The adhesive composition described in

[23] , represented by [representing].

[0052]

[26] An adhesive composition according to any one of [1] to

[25] , which does not contain resorcinol.

[0053]

[27] An adhesive composition according to any one of [1] to

[26] , for bonding with rubber.

[0054]

[28] An adhesive composition according to any one of [1] to

[26] , for bonding with organic fibers.

[0055]

[29] An adhesive composition according to any one of [1] to

[28] , for bonding rubber to organic fibers.

[0056]

[30] An organic fiber material comprising organic fibers and an adhesive layer covering the surface of the organic fibers, An organic fiber material characterized in that the adhesive layer comprises the adhesive composition described in any one of [1] to

[29] .

[0057]

[31] The organic fiber material according to

[30] , wherein the organic fiber is an organic fiber cord formed by twisting together a plurality of filaments.

[0058]

[32] The organic fiber material according to

[31] , wherein the organic fiber cord is formed by applying a lower twist and an upper twist (preferably the organic fiber cord is a cord formed by twisting together a plurality of filaments, and the cord formed by twisting together a plurality of filaments has an upper twist and a lower twist), the fiber thickness of the twisted cord is 100 dtex to 5000 dtex, and the number of twists for the lower twist is 10 to 50 times / 10 cm, and the number of twists for the upper twist is 10 to 50 times / 10 cm.

[0059]

[33] The organic fiber material according to

[31] or

[32] , wherein the adhesive layer is 0.5 to 6.0% by dry mass of the organic fiber cord.

[0060]

[34] The organic fiber material according to any one of

[30] to

[33] , wherein the organic fiber is made of nylon resin.

[0061] A rubber article characterized by being reinforced with an organic fiber material described in any one of

[35]

[30] to

[34] .

[0062]

[36] An organic fiber-rubber composite (particularly an organic fiber cord-rubber composite) comprising an organic fiber and rubber, wherein the organic fiber is coated with an adhesive composition according to any one of [1] to

[29] .

[0063] A tire characterized by using the organic fiber-rubber composite described in

[37]

[36] . [Effects of the Invention]

[0064] According to the present invention, it is possible to provide an adhesive composition that can ensure desired adhesion without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires using the same. [Brief explanation of the drawing]

[0065] [Figure 1] This is a schematic diagram illustrating an example of a process in which an organic fiber cord is coated with an adhesive composition by immersion treatment. [Figure 2] This is a schematic cross-sectional view showing an example of the organic fiber-rubber composite of the present invention. [Modes for carrying out the invention]

[0066] The adhesive compositions, organic fiber materials, rubber articles, organic fiber-rubber composites, and tires of the present invention will be described in detail below, based on embodiments thereof. These descriptions are for illustrative purposes only and do not limit the present invention in any way.

[0067] In this specification, when a range is described, unless otherwise specified, the edges of that range are also included within that range.

[0068] [Adhesive composition] The adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and further comprises one or more components selected from the group consisting of (C) an aqueous component having a plurality of phenolic hydroxyl groups in the molecule, (D) a water-soluble component containing an amide bond structure, (E) an amine compound, and (F) polyvinyl alcohol.

[0069] The adhesive composition of the present invention, with the above configuration, can achieve good adhesion without using resorcinol, and in particular, can ensure good adhesion between organic fibers and the coating rubber composition. In the adhesive composition of the present invention, (A) rubber latex having an unsaturated diene contributes to improved adhesion. Furthermore, by using (B) a polyvalent metal salt in combination with one or more components selected from the group consisting of (C) to (F) above, the tackiness of the rubber latex, measured as the mechanical stability of the adhesive liquid under shear strain, can be suppressed. In particular, in the process of coating organic fibers with the adhesive composition and drying and heat-curing it, the adhesion of the adhesive composition to rolls, etc., can be suppressed, resulting in good workability. Therefore, the adhesive composition of the present invention makes it possible to obtain the desired adhesiveness without using resorcinol, while also ensuring good workability during use.

[0070] Furthermore, since the adhesive composition of the present invention does not require the use of resorcinol, it can also reduce the environmental impact. Therefore, the adhesive composition of the present invention can be resorcinol-free. Furthermore, it is preferable that the adhesive composition of the present invention is formaldehyde-free. In this case, the environmental burden can be further reduced.

[0071] The adhesive composition of the present invention preferably further contains one or more components selected from the group consisting of (G) epoxide compounds and (H) aqueous compounds having a (thermally dissociable blocked) isocyanate group. In this case, even if formaldehyde and resorcinol are not included, excellent adhesion and mechanical stability can be achieved.

[0072] The adhesive composition of the present invention is preferable as an adhesive composition for bonding to rubber because it exhibits high adhesion to rubber. Furthermore, the adhesive composition of the present invention is preferable as an adhesive composition for bonding to organic fibers because it exhibits high adhesion to organic fibers. Moreover, the adhesive composition of the present invention is even more preferable as an adhesive composition for bonding rubber and organic fibers because it exhibits high adhesion to both rubber and organic fibers. In particular, the adhesive composition of the present invention is useful when applied to organic fiber cords, as described later.

[0073] <(A) Rubber latex containing unsaturated dienes> In the adhesive composition of the present invention, (A) rubber latex having an unsaturated diene can be a synthetic rubber latex having an unsaturated diene or a natural rubber latex.

[0074] In the adhesive composition of the present invention, the synthetic rubber latex having an unsaturated diene means a synthetic rubber latex containing an unsaturated diene that is vulcanizable with sulfur.

[0075] In one embodiment of the present invention, the rubber latex having (A) unsaturated diene contained in the adhesive composition is a component for bonding the adhesive layer of the adhesive composition to the coated rubber composition which is the adherend, similar to the rubber glue described above. The rubber latex having (A) unsaturated diene is compatible with the rubber polymer contained in the coated rubber composition which is the adherend, and furthermore, the unsaturated diene portion undergoes co-vulcanization to form a rubber co-vulcanization bond. As a result, the adhesive composition of the present invention containing rubber latex having (A) unsaturated diene can, for example, effectively bond an organic fiber cord to a coated rubber composition.

[0076] The rubber latex having the (A) unsaturated diene is not limited to, but examples include synthetic rubber latex such as styrene-butadiene copolymer rubber latex, vinylpyridine-styrene-butadiene copolymer rubber latex, carboxyl group-modified styrene-butadiene copolymer rubber latex, nitrile rubber latex, and chloroprene rubber latex. These may be used individually or in combination of two or more.

[0077] Among the above, vinylpyridine-styrene-butadiene copolymer rubber latex is preferred. Vinylpyridine-styrene-butadiene copolymer rubber latex has been widely used in adhesive compositions and articles such as tires, and in the adhesive composition of the present invention, it provides a good bond between the adhesive layer and the adherend, and has the advantage of being relatively flexible and pliable, which allows the organic fiber cord to deform without the adhesive layer splitting.

[0078] Furthermore, the content of rubber latex having the (A) unsaturated diene in the total solid content of the adhesive composition of the present invention (solid content) 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. Also, the content of rubber latex having the (A) unsaturated diene is preferably 99.5% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. When the content of rubber latex having the (A) unsaturated diene is 25% by mass or more, the compatibility between the rubber polymers of the adherend rubber composition and the rubber latex contained in the adhesive composition becomes more appropriate, and the adhesion state of the coated rubber in the organic fiber-rubber composite becomes better. On the other hand, if the content of the rubber latex having (A) unsaturated diene is 99.5% by mass or less, compared to rubber glue, it is possible to secure a relatively constant amount of coating components that suppress the adhesion of latex included as other components in the adhesive composition, thereby obtaining mechanical stability of the adhesive liquid under shear strain, and suppressing adhesion of the adhesive composition to the apparatus shown in Figure 1 during the process of coating the fibrous material to be adhered with the adhesive composition. Furthermore, the problem of the coated adhesive composition becoming rough and its adhesion to the coated rubber composition decreasing is less likely to occur, thereby improving adhesion.

[0079] The rubber latex having the aforementioned (A) unsaturated diene can be obtained, for example, by dissolving an emulsifier such as potassium rosinate in water, adding a mixture of monomers thereto, further adding an electrolyte such as sodium phosphate and peroxides as polymerization initiators to carry out polymerization, and then, after reaching a predetermined conversion rate, adding a charge transfer agent to stop the polymerization, and further removing the remaining monomers. It is also preferable to use a chain transfer agent during polymerization.

[0080] The emulsifier used to emulsify a mixture of monomers in an aqueous system may be one or more of the following: anionic surfactants such as alkali metal salts of fatty acids, alkali metal salts of rosinic acid, sodium formaldehyde condensed naphthalene sulfonate, sulfate esters of higher alcohols, alkylbenzene sulfonates, or aliphatic sulfonates; or nonionic surfactants such as alkyl esters, alkyl ethers, or alkylphenyl ethers of polyethylene glycol. Among these emulsifiers, it is preferable to include metal salts of rosinic acid, particularly alkali metal salts of rosinic acid. These can be used alone, or in combination with two or more other emulsifiers. Rosin acid is a mixture of resin acids with similar chemical structures, mainly composed of tricyclic diterpenes obtained from pine resin and the like. These resin acids have three ring structures, two double bonds, and one carboxyl group. The double bond portion has highly reactive functional groups, such as esterification with the methylol terminus of unsaturated carboxylic acids or resol-type phenolic resins at the carboxyl group portion. The amount of emulsifier used is typically 0.1 to 8 parts by mass, preferably 1 to 5 parts by mass, per 100 parts by mass of the total monomers used in latex polymerization.

[0081] Examples of polymerization initiators that can be used include water-soluble initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate, redox initiators, or oil-soluble initiators such as benzoyl peroxide. Among these, potassium persulfate is preferred.

[0082] Examples of the chain transfer agents that can be used include monofunctional alkyl mercaptans such as n-hexyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, and t-hexyl mercaptan; difunctional mercaptans such as 1,10-decanedithiol and ethylene glycol dithioglycolate; trifunctional mercaptans such as 1,5,10-canditrithiol and trimethylolpropane tristhioglycolate; tetrafunctional mercaptans such as pentaerythritol tetrakisthioglycolate; disulfides; halogen compounds such as carbon tetrachloride, carbon tetrabromide, and ethylene bromide; and α-methylstyrene dimer, terpinolene, α-terpinene, dipentene, and allyl alcohol. These can be used individually or in combination of two or more. Among these chain transfer agents, alkyl mercaptans are preferred, and n-octyl mercaptans and t-dodecyl mercaptans are more preferred. Of these, t-dodecyl mercaptans are preferred. The amount of such chain transfer agent used is usually 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass, per 100 parts by mass of the total monomers used in latex polymerization.

[0083] In addition to the components listed above, the latex may also contain, as needed, general-purpose additives such as anti-aging agents like hindered phenols, silicone-based, higher alcohol-based, or mineral oil-based defoamers, reaction stoppers, and antifreeze agents. Furthermore, components (B) to (F) of the present invention can be added to latex, but in that case, they should be included in the adhesive composition of the present invention, which consists of (A) and (B).

[0084] <<Vinylpyridine-styrene-butadiene copolymer rubber latex>> The vinylpyridine-styrene-butadiene copolymer rubber latex is obtained by tern-copolymerizing a vinylpyridine monomer, a styrene monomer, and a conjugated diene-based butadiene monomer, but these monomers may further contain other monomers that can be copolymerized.

[0085] Here, the vinylpyridine monomer includes vinylpyridine and substituted vinylpyridine in which a hydrogen atom in the vinylpyridine is replaced by a substituent. Examples of such vinylpyridine monomers include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and 5-ethyl-2-vinylpyridine, among which 2-vinylpyridine is preferred. These vinylpyridine monomers may be used individually or in combination of two or more.

[0086] The styrene monomers include styrene and substituted styrene in which hydrogen atoms in the styrene are replaced by substituents. Examples of the styrene monomers include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diinopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, and hydroxymethylstyrene, with styrene being preferred among these. These styrene monomers may be used individually or in combination of two or more.

[0087] Examples of the aforementioned conjugated diene-based butadiene monomers include aliphatic conjugated butadiene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene, with 1,3-butadiene being preferred among these. These conjugated diene-based butadiene monomers may be used individually or in combination of two or more.

[0088] Known methods can be used to synthesize the vinylpyridine-styrene-butadiene copolymer rubber latex. Specifically, for example, the method described in Japanese Patent Application Publication No. 9-78045, based on the inventors' research, can be used. By using these methods, various compositions and intraparticle structures can be given to the vinylpyridine-styrene-butadiene copolymer rubber latex within the same particle, such as copolymers with uniform or different composition ratios.

[0089] Regarding the vinylpyridine-styrene-butadiene copolymer rubber latex, commercially available copolymers having a uniform monomer mixing ratio within the same particle include Nipol 2518 from Zeon Corporation and Piratex from A&L Japan Co., Ltd. Furthermore, commercially available copolymers having different monomer mixing ratios within the same particle include V0658 from JSR Corporation. All of these can be used as (A) rubber latex having an unsaturated diene in the adhesive composition of the present invention.

[0090] In the vinylpyridine-styrene-butadiene copolymer rubber latex, the monomer ratio of vinylpyridine:styrene:butadiene is not particularly limited, but 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 mass of vinylpyridine, 10-40% by mass of styrene, and 45-75% by mass of butadiene. If the vinylpyridine is 5% by mass or more, the amount of pyridine moieties that have a vulcanization promoting effect within the rubber component becomes appropriate, and the degree of crosslinking by sulfur increases, further improving the adhesive strength of the entire adhesive layer. If it is 20% by mass or less, the degree of crosslinking of the rubber does not become over-vulcanized, and a hard adhesive can be made. Furthermore, if the styrene is 10% by mass or more, the strength of the latex particles and the adhesive layer is made sufficient, and the adhesive strength is further improved. If it is 40% by mass or less, it leads to ensuring adhesive strength while appropriately co-vulcanizing the adhesive layer and the adherend rubber. Furthermore, if the butadiene content is 45% by mass or more, it becomes possible to form more sufficient crosslinks, and if it is 75% by mass or less, the crosslinking is moderate, and good durability due to changes in volume and modulus can be ensured. The composition ratio of the vinylpyridine:styrene:butadiene monomer mixture can preferably be, for example, 15:15:70.

[0091] In the present invention, as the rubber latex having an unsaturated diene (A), natural rubber latex can be used in addition to synthetic rubber latex having an unsaturated diene. The natural rubber latex is not particularly limited, and for example, field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized latex treated with surfactants or enzymes, and combinations thereof can be used. Among these, field latex is preferred.

[0092] (B) Polyvalent metal salts The polyvalent metal salt (B) used in the adhesive composition of the present invention is not particularly limited, but any salt of a metal ion with a valency of 2 or higher can be used. If the polyvalent metal salt (B) is a salt of a metal ion with a valency of 2 or higher, the adhesive strength of the adhesive composition to organic fibers can be made higher. Preferably, (B) the polyvalent metal salt is a water-soluble metal salt, and particularly preferably, a metal salt that forms a 4-coordinate or 6-coordinate polyvalent metal ion. If (B) the polyvalent metal salt is water-soluble and forms a 4-coordinate or 6-coordinate polyvalent metal ion, the adhesive strength of the adhesive composition to organic fibers can be further increased. (B) Polyvalent metal salts may be used individually or in combination of two or more types.

[0093] The polyvalent metal salt (B) is not particularly limited, but a metal salt that can dissolve in water as a solvent as a polyvalent metal ion (including complex ions) is preferred. This is because when the metal ion is polyvalent rather than monovalent, it can interact with multiple components, enabling ionic crosslinking or coordination crosslinking between the fiber surface of the adherend, interactable parts of the adhesive composition, and sulfur-active species that migrate from the adherend rubber during vulcanization, thereby enhancing the adhesion or cohesive force with the components. Particularly preferred polyvalent metal ions are 4-coordinate or 6-coordinate polyvalent metal ions. Examples of these metal salts include mordants used as dyeing chemicals for fibers, but preferred examples include metal salts of aluminum, iron, chromium, copper, tin, nickel, and titanium, and among these, metal salts containing iron and / or copper are even more preferred. (B) If the polyvalent metal salt is a metal salt containing one or more metals selected from the group consisting of iron and copper, the adhesive strength of the adhesive composition to organic fibers can be made particularly high. Specific examples of metal salts are not limited to iron chloride, tin chloride, alum, copper sulfate, copper acetate, copper oxalate, copper gluconate, aluminum acetate, or natural mordants such as enamel or lye containing these polyvalent metal ions. Of these, it is particularly preferable to include a metal salt of copper ions or iron ions. In a preferred embodiment of the present invention, copper gluconate or iron chloride, which are used in food additives for copper supplementation, are used.

[0094] The aforementioned (B) polyvalent metal salt can be dissolved in water by stirring and added to the adhesive composition as an aqueous solution of about 0.01 to 5% by mass. Within this range, it is possible to enhance the fixing effect on the surface of organic fibers, similar to a mordant in dyeing organic fibers, thereby increasing the adhesive strength to organic fibers.

[0095] Furthermore, by including (B) a polyvalent metal salt and one or more components selected from the group consisting of (C) an aqueous component having multiple phenolic hydroxyl groups in its molecule, (D) a water-soluble component containing an amide bond structure, (E) an amine compound, and (F) polyvinyl alcohol, charge transfer interactions occur between the anionic or amine groups contained in these compounds (C) to (F) and the cationic metal ions of the polyvalent metal salt (B). This increases the resistance to cohesive fracture within the adhesive composition layer, thereby improving adhesion to organic fibers.

[0096] The content of the polyvalent metal salt (B) in the total solid content of the adhesive composition of the present invention (solid content) is not particularly limited, but is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more. Furthermore, the content of the polyvalent metal salt (B) is preferably 3% by mass or less, and more preferably 1.5% by mass or less. This is because if the content of the polyvalent metal salt (B) is 0.05% by mass or more, the adhesion between the organic fiber and the coated rubber composition will be better. Furthermore, if the content of the polyvalent metal salt (B) is 3% by mass or less, the thickening due to the coagulation effect of the polyvalent metal salt in the adhesive composition can be suppressed, the amount of alkaline ions will not be excessive, and the decrease in adhesion due to overvulcanization under heat will be suppressed, which is also environmentally friendly.

[0097] <(C) Aqueous component having multiple phenolic hydroxyl groups within the molecule> One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (C) an aqueous component having a plurality of phenolic hydroxyl groups in the molecule.

[0098] The aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is preferably (C-1) an aqueous component of plant origin having multiple phenolic hydroxyl groups in the molecule, or (C-2) an aqueous compound having a structure in which aromatics are linked by methylene bonds. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition is improved.

[0099] As the (C-1) aqueous component of plant origin having multiple phenolic hydroxyl groups in the molecule, a plant-derived polymer having multiple phenolic hydroxyl groups in the molecule is preferred, and water-soluble polyphenols are preferred. Specifically, examples include polyphenols such as lignin, tannin, tannic acid, flavonoids, and their derivatives. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition becomes even better.

[0100] The aqueous component (C) having multiple phenolic hydroxyl groups in its molecule has the effect of a phenolic antioxidant because it has multiple phenolic hydroxyl groups in its molecule, and can suppress the oxidative degradation reaction at the saturated diene portion of the rubber latex containing (A) unsaturated diene in the adhesive composition, thereby preventing the reduction of the amount of unsaturated diene on the surface of the adhesive composition over time due to radical oxidation reactions caused by heat and light. Therefore, when the aqueous component (C) having multiple phenolic hydroxyl groups in its molecule is used in the adhesive composition, the adhesion between the organic fiber and the coated rubber composition over time is reduced, and the adhesion is good.

[0101] Research has long been conducted on separating polyphenols such as lignin and tannin, which are components of wood and bark, and reacting them with formaldehyde to produce adhesives (see, for example, Japanese Patent Publication No. 07-53858). However, there is little knowledge on producing water-based adhesive compositions that do not contain resorcinol, and in particular, little knowledge on producing water-based adhesive compositions that contain rubber latex containing unsaturated dienes.

[0102] The aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is preferably lignin or a derivative thereof. Lignin is a major component of the plant cell wall, along with polysaccharides such as cellulose. Lignin contains functional groups such as hydroxyl groups, methoxy groups, carbonyl groups, and carboxyl groups, but phenolic hydroxyl groups in particular are highly reactive and can interact with cationic substances.

[0103] Lignin is a polymer with a structure based on phenylpropane, but its molecular structure is diverse. As a large biomolecule that forms a three-dimensional network structure, its molecular structure has not yet been fully elucidated.

[0104] Natural lignin forms strong composite materials with polysaccharides such as cellulose within plant cell walls, making the isolation of natural lignin without altering its chemical structure extremely difficult. Various industrial separation methods are used to extract lignin from materials such as wood. The lignin obtained after separation includes sulfonic acid lignin, kraft lignin, soda lignin, and steam-exploded lignin. Among these industrially handled lignins, lignosulfonates or kraft lignin, which can be obtained on a large scale from pulp wastewater from the chemical pulping process of paper pulp manufacturing, are well-known materials from the standpoint of availability and economic efficiency.

[0105] Other examples of lignins include lignin modified by hydroxymethylation, epoxidation, denitrification, acylation, or hydroxylation; diethanolamine-modified lignin; enzyme-modified lignin; laccase-modified lignin; urea-modified lignin; lignosulfonates; Alcel-processed lignin; alkali-granit-processed lignin; polyethylene glycol-added lignin, and the like.

[0106] The Kraft lignin described above is lignin derived from a chemical pulping method called Kraft pulping (high temperature and high pressure reaction), which is a high-temperature and high-pressure reaction in which wood chips, such as hardwoods, softwoods, deciduous trees, bamboo, kenaf, and bagasse, are fed into a digester along with a digestate containing sodium hydroxide / sodium sulfide, etc. The Kraft lignin is obtained by adding acid and / or carbon dioxide to the Kraft waste liquid obtained after Kraft pulping to precipitate the dissolved lignin-modified product, and then dehydrating and washing the resulting precipitate. Furthermore, the precipitate after dehydration and washing can be purified by adding an organic solvent such as alcohol or acetone to dissolve it, separating insoluble impurities and drying it, or by modifying it by introducing various functional groups as needed. The Kraft lignin described above can be obtained and used from commercially available products. Among them, the reagent name "Lignin,alkali,kraft" (CAS Number: 8068-05-1) manufactured by Sigma-Aldrich Co. LLC is preferred.

[0107] The aforementioned sulfonic acid lignin is ligninsulfonic acid and its salts obtained from wastewater leached from sulfurous acid pulp in a chemical pulping method using sulfurous acid pulp, in which wood chips are reacted at high temperature and pressure with a pulping solution containing sulfurous acid and / or sulfites. Calcium ligninsulfonate, sodium ligninsulfonate, potassium ligninsulfonate, and magnesium ligninsulfonate salts are particularly preferred. Among these, sodium ligninsulfonate is preferred. These sulfonic acid lignins are available commercially; for example, as ligninsulfonate salts or modified ligninsulfonate salts, products such as the Sun Extract series from Nippon Paper Industries Co., Ltd. can be used.

[0108] High value-added products of lignin sulfonates include, for example, not only high-purity products, but also partially desulfonated (low)sulfonated lignin sulfonates 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, Japanese Patent Publication No. 2016-135834). As high-purity lignin sulfonates or modified lignin sulfonates, the Pearllex series of Nippon Paper Industries Co., Ltd. products can be used, and as partially desulfonated lignin sulfonic acid, the Vanillex series of Nippon Paper Industries Co., Ltd. products can be used. Among these, the reagent name "Lignin (Alkali)" (CAS Number: 8061-51-6, solid powder) manufactured by Tokyo Chemical Industry Co., Ltd., which is a partially desulfonated (low)sulfonated lignin sulfonate with a reduced degree of sulfonation, is preferred.

[0109] The aforementioned tannins are a group of polyphenols found in a wide range of plants, including not only woody trees but also fruits, leaves, and seeds, such as grapes, persimmons, berries, cloves, legumes, herbs, tea leaves, and cocoa beans. Tannin molecules generally contain numerous hydroxyl groups and often carboxyl groups, and tend to form strong complexes and composites with a wide range of polymers.

[0110] The aforementioned tannins include tannic acid, proanthocyanidins, flavonoids, gallic acid esters, catechins, and derivatives such as their salts and modified forms. Furthermore, the aforementioned flavonoids, which are ubiquitous in the leaves, stems, and bark of plants and are generally called tannins, consist of hydrolyzable tannins and condensed tannins. These tannins can be distinguished by boiling them in dilute hydrochloric acid: condensed tannins produce an insoluble precipitate, while hydrolyzable tannins undergo hydrolysis to produce water-soluble substances.

[0111] The aforementioned tannins, both hydrolyzable and condensed, are water-soluble and can be obtained by extraction from plant materials such as wood, bark, leaves, fruits, pods, and insect sacs using methods such as hot water extraction. Hydrolyzable tannins can be obtained, for example, from the wood of chaste and nuts, oak bark, tea leaves, and insect sacs of galls and gallnuts, while condensed tannins can be obtained from the wood of quebracho, mimosa bark, persimmon and buckwheat seeds, etc. Among these, tannic acid obtained from galls, etc., manufactured by Nacalai Tesque Co., Ltd., reagent name "Tannic Acid" (CAS Number: 1401-55-4-6, solid powder), and tannic acid obtained from mimosa bark, manufactured by Kawamura Trading Co., Ltd., trade name "Mimosa" (solid powder), are preferred as hydrolyzable tannins, and "Mimosa" is preferred as a condensed tannin obtained from mimosa bark.

[0112] The aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is preferably an aqueous compound consisting of (a) an aromatic hydrocarbon having phenolic hydroxyl groups in the molecule and formaldehyde. In this case as well, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition will be better.

[0113] Furthermore, it is even more preferable that the aqueous component (C) having multiple phenolic hydroxyl groups in the molecule is an aqueous compound consisting of a polycyclic aromatic hydrocarbon having phenolic hydroxyl groups in the molecule and formaldehyde. Specifically, examples include salts of β-naphthalene sulfonic acid formaldehyde condensate. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coating rubber composition becomes even better.

[0114] The aqueous component (C) having multiple phenolic hydroxyl groups in the molecule can, in one embodiment of the adhesive composition of the present invention consisting of (A) a rubber latex having an unsaturated diene and (B) a polyvalent metal salt, provide higher adhesion to organic fibers as follows.

[0115] First, the aqueous component (C) having multiple phenolic hydroxyl groups in its molecule becomes more readily fixed to the surface of the rubber latex having (A) an unsaturated diene by adding (B) a polyvalent metal salt. This is because rubber latex having (A) an unsaturated diene is generally synthesized using an anionic emulsifier, and a cationic polyvalent metal salt can intervene between the functional groups of the anionic emulsifier on the surface of the rubber latex having (A) an unsaturated diene and the phenolic hydroxyl groups of the aqueous component having multiple phenolic hydroxyl groups in its molecule, allowing for charge transfer interactions.

[0116] Next, the aqueous component (C) having multiple phenolic hydroxyl groups in its molecule becomes more readily fixed to the surface of the organic fiber to be attached, such as nylon, by adding the polyvalent metal salt (B). This is because a cationic metal salt intervenes between the anionic groups generated by oxidative decomposition of the polymer in the organic fiber to be attached and the phenolic hydroxyl groups of the aqueous component (C) having multiple phenolic hydroxyl groups in its molecule, allowing for charge transfer interactions. This is known as metal mordanting, and it is because the aqueous component having phenolic hydroxyl groups that can form complex salts with metal ions can create water-insoluble metal complex salts on the organic fiber and fix them in place.

[0117] In such metal mordanting, (C) an aqueous component having multiple phenolic hydroxyl groups in its molecule readily forms a complex salt with (B) a polyvalent metal salt that is 4-coordinate or 6-coordinate, specifically metals such as aluminum, iron, chromium, copper, tin, and nickel, and is easily fixed to the surface of organic fibers. Furthermore, in such metal mordanting, it is preferable that (C) the aqueous component having multiple phenolic hydroxyl groups in its molecule has the structure of a tannin or a dye in metal mordanting that has a sulfonic acid group, as this facilitates the formation of a complex salt.

[0118] Furthermore, in particular, when (B) the polyvalent metal salt is a metal salt containing iron or copper, (C) the aqueous component having phenolic hydroxyl groups preferably has multiple phenolic hydroxyl groups. This is because metals that readily act as oxidizing catalysts, such as iron or copper, have some of their multiple phenolic hydroxyl groups as quinone structures, and when fixed to organic fibers, the reduced form (leuco form) of the dye solution becomes quinone-type on the fibers, similar to vat dyes, resulting in better fixation to organic fibers. Generally, plant-derived polyphenols are known to have their aromatic ring structure and multiple phenolic hydroxyl groups partially oxidized by copper peroxidase, etc., to form quinone structures, and further higher-order structures are formed by crosslinking. Therefore, it is preferable that some of the multiple phenolic hydroxyl groups can form quinone structures, and it is even more preferable that they are water-soluble polyphenols or processed products of ligninsulfonic acid obtained therefrom. Furthermore, the ligninsulfonic acid can preferably be used if it is a partially desulfonated ligninsulfonic acid, as it exhibits good dispersibility on the surface of the organic fibers when fixing them (see Japanese Patent Publication No. 2002-146028).

[0119] The content of the aqueous component having multiple phenolic hydroxyl groups in the molecule (C) in relation to the total solid content of the adhesive composition (solid content) is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Furthermore, the content of the aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is preferably 60% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. This is because if the content of the aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is 1% by mass or more, the adhesion between the organic fiber and the coated rubber composition will be better. Furthermore, if the content of the aqueous component having multiple phenolic hydroxyl groups in the molecule (C) is 50% by mass or less, it becomes possible to secure a relatively high amount of other components such as rubber latex to be incorporated into the adhesive composition, and as a result, the adhesion to the rubber to be adhered will be better.

[0120] <(D) Water-soluble components containing an amide bond structure> One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (D) a water-soluble component containing an amide bond structure.

[0121] The (D) water-soluble component containing the amide bond structure is preferably a (D-1) water-soluble component containing a peptide structure, or a (D-2) water-soluble compound containing an acrylamide structure. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition is improved.

[0122] As the water-soluble component containing the (D-1) peptide structure, one or more water-soluble components selected from the group consisting of proteins such as polylysine, casein, and gelatin, and polypeptides obtained by hydrolyzing proteins (derived from wool, milk, beans, silk, fish scales, skin, etc.) can be suitably used. If the water-soluble component containing the (D) amide bond structure is one or more water-soluble components selected from the group consisting of proteins and polypeptides obtained by hydrolyzing proteins, the adhesion between the organic fibers and the coating rubber composition will be even better when the adhesive composition is used on organic fibers. Furthermore, if the water-soluble component containing the (D) amide bond structure is one or more proteins selected from the group consisting of casein and gelatin, or polypeptides obtained by hydrolyzing proteins derived from wool, milk, beans, silk, fish scales, or skin, the adhesion between the organic fibers and the coating rubber composition will be particularly good when the adhesive composition is used on organic fibers.

[0123] Furthermore, the water-soluble compound containing the (D-2) acrylamide structure is preferably an aqueous compound of polyacrylamide or a modified version thereof. Amphoteric polyacrylamide can be suitably used as the aqueous compound of polyacrylamide or a modified version thereof. When the water-soluble component containing the (D) amide bond structure is an aqueous compound of polyacrylamide or a modified version thereof, the adhesion between the organic fibers and the coating rubber composition is further improved when the adhesive composition is used on organic fibers. Furthermore, when the water-soluble component containing the (D) amide bond structure is amphoteric polyacrylamide, the adhesion between the organic fibers and the coating rubber composition is particularly good when the adhesive composition is used on organic fibers.

[0124] The water-soluble component containing the (D) amide bond structure becomes more readily fixed to the surface of organic fibers such as nylon by adding the (B) polyvalent metal salt. This is because charge transfer interactions can occur between the anionic groups generated by oxidative decomposition of the polymer in the organic fibers and the cationic metal salt interacting with the water-soluble component containing the (D) amide bond structure.

[0125] In this case, the interaction between a polyvalent metal salt with four or six coordination and a water-soluble component containing an amide bond structure (D) can occur if the water-soluble component containing the amide bond structure (D) is a water-soluble component containing a peptide structure (D-1), particularly if it is one or more water-soluble components selected from the group consisting of proteins such as polylysine, casein, and gelatin, and polypeptides obtained by hydrolyzing proteins (derived from wool, milk, beans, silk, fish scales, skin, etc.). In this case, the interaction can occur by adopting a structure in which nitrogen, sulfur, and oxygen-containing moieties such as histidine and tyrosine in the protein act as ligands and coordinate to the metal ion, as seen in copper proteins, for example. Furthermore, the water-soluble component containing the (D) amide bond structure can interact with polyvalent metal salts via copolymerized anionic functional groups or carboxyl groups formed by the decomposition of the polyacrylamide bond, similar to the fixing effect of polyacrylamide and polyvalent metals on fibers in the papermaking process.

[0126] The content of the water-soluble component containing the (D) amide bond structure in the total solid content of the adhesive composition (solid content) is not particularly limited, but is preferably 0.1% by mass or more, and preferably 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 8% by mass or less. If the content of the water-soluble component containing the (D) amide bond structure is 0.1% by mass or more, its function as an emulsifier reduces the tackiness of the rubber latex when coated with the rubber latex having the (A) unsaturated diene, and if it is 0.2% by mass or more, it becomes stable. On the other hand, if the content of the water-soluble component containing the (D) amide bond structure exceeds 25% by mass, the amount contained in the adhesive composition becomes too large. This is because when the amount of resin filling the voids between rubber latex particles exceeds 25%, the coating of (D) amide fixed to the rubber latex increases, and the exposure of the rubber latex on the surface of the adhesive layer during vulcanization decreases. Furthermore, if the content of the water-soluble component containing the (D) amide bond structure is 15% by mass or less, the relative proportion of thermoplastic resin components without crosslinking reactive groups, such as polyacrylamide, in the resin component forming the backbone of this adhesive layer becomes low, improving the heat resistance of the adhesive layer. Moreover, if the content of the water-soluble component containing the (D) amide bond structure is 8% by mass or less, a moderate effect is obtained as an agent that improves the coating of rubber latex and adhesion between organic fiber surfaces or components blended into the adhesive composition, which is preferable.

[0127] <<(D-1) Water-soluble component containing peptide structure>> One preferred embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (D-1) a water-soluble component containing a peptide structure.

[0128] Suitable water-soluble components containing the (D-1) peptide structure include proteins derived from natural products such as wool, milk, beans, silk, fish scales, and skin, as well as proteins synthesized through biosynthesis and other methods, and polypeptides obtained by hydrolyzing proteins. Examples of the aforementioned proteins include gelatin and casein. These proteins are water-soluble proteins in which collagen molecules found in connective tissues such as animal skin, bones, scales, tendons, and hair, or in milk, are treated with acids or alkalis, heated with water to decompose them, extracted, and purified. They are denatured collagen and refer to linear polymers of amino acids.

[0129] In the adhesive composition of the present invention, a water-soluble component containing a (D-1) peptide structure, such as a protein like gelatin or casein, forms a network in water at or below the gelation temperature, with gelatin molecules forming a network with each other, thereby coating the surface of the rubber latex having an (A) unsaturated diene. In one example, the rubber latex having an (A) unsaturated diene has a negative (-) charge due to the carboxylic acid of the emulsified rosinate (emulsifier) ​​on its surface. The cationic groups of the amino group (-NH2) and thiol group (-SH) of the gelatin molecule are adsorbed to this by electrostatic attraction to form a complex, and this coating suppresses the tackiness of the rubber latex having an (A) unsaturated diene (latex-protein protective film effect). As a result, the adhesive composition containing a water-soluble component containing a (D-1) peptide structure suppresses the tackiness of the rubber latex, which is measured as the mechanical stability of the adhesive liquid under shear strain. This makes it possible to suppress the adhesion of the adhesive composition to rolls, etc., in the process of coating organic fiber cords, etc., with the adhesive composition and drying and heat-curing the adhesive, resulting in improved workability and good adhesion between the adhesive composition and the rubber composition to be adhered.

[0130] Furthermore, as mentioned above, by including (B) a polyvalent metal salt, the water-soluble component containing the (D-1) peptide structure acts as a ligand and interacts with the metal ion in a coordinated structure. This increases the charge interaction cohesive force between the water-soluble components containing the (D-1) peptide structure, and also enhances the ability of the water-soluble component containing the (D-1) peptide structure to fix to the anionic groups on the surface of the organic fiber to be adhered via the (B) polyvalent metal salt, resulting in particularly good adhesion between the adhesive composition and the adherend rubber composition.

[0131] (D-1) The water-soluble component containing the peptide structure is not particularly limited, but can be obtained by extracting it from collagen, which is a component derived from the secretions of biological tissues such as skin, bones, tendons, etc. of animals (e.g., pigs, cows, rabbits, sheep, mice, birds, fish, and humans) by applying heat. The collagen can also be obtained as a commercially available product. Furthermore, collagen extracted from biological tissue can also be produced using genetic engineering technology, etc. Furthermore, gelatin can also be obtained by acid-treating animal skin or milk secretions (acid-treated gelatin), or by alkali-treating animal bones (alkali-treated gelatin). These gelatins are composed of polypeptide chains with a number-average molecular weight of approximately 100,000, their dimers and trimers, and polypeptide chains obtained by hydrolysis of these, with a number-average molecular weight of approximately 300,000.

[0132] The gelatin mentioned above is not particularly limited, as long as it is a gelatin that has the ability to solidify into a jelly-like state and form a gel by sol-gel transition when the temperature is lowered by heating an aqueous gelatin solution and then cooling it.

[0133] The gelatin or milk secretion proteins obtained as described above can be further decomposed by heating, acid, alkali, or proteolytic enzymes to obtain polypeptides with a number average molecular weight of 2,000 to 26,000, which can then be used. These can be used individually or in combination of two or more. In the present invention, polypeptides obtained by hydrolyzing milk secretion proteins can be preferably used.

[0134] <<(D-2) Water-soluble compounds containing acrylamide structure>> A preferred embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (D-2) a water-soluble compound containing an acrylamide structure.

[0135] By using a water-soluble compound containing a (D-2) acrylamide structure together with the (A) unsaturated diene rubber latex in the adhesive composition, the acrylamide compound covers the surface of the rubber latex particles, suppressing aggregation of the rubber latex particles. As a result, the dispersibility of the rubber latex when subjected to mechanical load is improved, and excellent mechanical stability can be achieved. As a result, adhesive compositions containing a water-soluble compound with a (D-2) acrylamide structure can suppress adhesion of the adhesive composition to rolls, etc., during the process of coating organic fiber cords with the adhesive composition for organic fiber cords and drying / heat curing, resulting in improved workability. Furthermore, by fixing the water-soluble compound containing the (D-2) acrylamide structure to the rubber latex surface having an (A) unsaturated diene, the adhesion between the adhesive composition and the adherend rubber composition is improved.

[0136] Furthermore, as mentioned above, by including (B) a polyvalent metal salt, the water-soluble compound containing the (D-2) acrylamide structure has an interaction that allows it to fix to metal ions, similar to how polyacrylamide is used as a flocculant for heavy metal ions in aqueous solutions. This increases the charge interaction-based cohesive force between the components of the water-soluble compound containing the (D-2) acrylamide structure, and also enhances the ability of the water-soluble compound containing the (D-2) acrylamide structure to fix to the anionic groups on the surface of the organic fiber to be adhered via the (B) polyvalent metal salt, resulting in good adhesion between the adhesive composition and the adherend rubber composition.

[0137] The water-soluble compound containing the (D-2) acrylamide structure may include a structure comprising (a) a copolymer of (meth)acrylamide and / or (b) a vinyl monomer having a cationic group and / or (c) a vinyl monomer having an anionic group and / or (d) a copolymer of other copolymerizable polymerizable monomers.

[0138] In the present invention, (a)(meth)acrylamide refers to acrylamide and methacrylamide. Hereafter, (meth)acrylic is considered synonymous with acrylic and / or methacrylic, and will be abbreviated accordingly. In compounds containing an acrylamide structure having a cationic group and / or a carboxyl group, the "acrylamide structure" can be obtained from a structure obtained by polymerizing an acrylamide component mainly consisting of (a)(meth)acrylamide. (meth)acrylamide can be used alone or in combination of two types. Preferably, from an economic standpoint, it is better to use acrylamide alone.

[0139] The content of (a) (meth)acrylamide is, for example, 50 mol% or more, preferably 60 mol% or more, and preferably 100 mol% or less, relative to the total monomers constituting the acrylamide polymer. If the content of component (a) is less than 50 mol%, the adhesive strength due to cohesive forces such as hydrogen bonding by the amide moiety will be reduced.

[0140] Examples of vinyl monomers having a cationic group (b) include vinyl monomers having a primary amino group, a secondary amino group, a tertiary amino group, or a quaternary ammonium salt.

[0141] Examples of vinyl monomers having a primary amino group include 2-propenylamine, 2-methyl-2-propenylamine; or inorganic acid salts such as hydrochloride and sulfate of the above primary amino monomers; or organic acid salts such as formate and acetate of the above primary amino monomers.

[0142] Examples of vinyl monomers having a secondary amino group include di(2-propenyl)amine (diallylamine), di(2-methyl-2-propenyl)amine; or the hydrochloride salts and inorganic acid salts such as sulfates of the above secondary amino monomers; or the formate salts and organic acid salts such as acetates of the above secondary amino monomers.

[0143] Examples of vinyl monomers having a tertiary amino group include dialkylaminoalkyl(meth)acrylates such as N,N-dimethylaminoethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, and N,N-dimethylaminopropyl(meth)acrylate; dialkylaminoalkyl(meth)acrylamides such as N,N-dimethylaminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and N,N-diethylaminopropyl(meth)acrylamide; tertiary amine monomers such as allylamine, diallylamine, and vinylpyridine; or inorganic acid salts such as hydrochloride and sulfate of the aforementioned tertiary amino monomers; or organic acid salts such as formate and acetate of the aforementioned tertiary amino monomers. Among these, N,N-dimethylaminoethyl(meth)acrylate is preferred in terms of polymerizability and cost.

[0144] The vinyl monomers having the quaternary ammonium salts are cationic copolymerizable monomers having a quaternary ammonium group and an ethylenically double bond. Examples include vinyl monomers of quaternary ammonium salts obtained by reacting the vinyl monomer having the tertiary amino group with an alkylating agent (quaternary derivatives of tertiary amino monomers), and quaternary derivatives of diallylamine derivative monomers in which the tertiary amino group has been quaternized. These quaternary ammonium monomers can be used alone or in combination of two or more types.

[0145] Examples of quaternary compounds of the aforementioned tertiary amino monomers include alkyl halides such as methyl chloride and methyl bromide; aralkyl halides such as benzyl chloride; dimethyl sulfate, diethyl sulfate, epichlorohydrin, glycidyltrialkylammonium chloride, and 3-chloro-2-hydroxypropyltrimethylammonium chloride, which are used as alkylating agents to convert the tertiary amino group of the polymerizable monomer having the above-mentioned tertiary amino group into a quaternary compound. Among the quaternary monomers of these tertiary amino monomers, quaternary monomers of dialkylaminoalkyl(meth)acrylamide are preferred. Preferred alkylating agents for quaternization include quaternary monomers derived from methyl chloride or benzyl chloride.

[0146] Examples of quaternary derivatives of the diallylamine monomer include diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldiethylammonium chloride, diallyldibutylammonium chloride, and diallylmethylethylammonium chloride. Among the quaternary derivatives of these diallylamine monomers, diallyldimethylammonium chloride is a preferred example.

[0147] In the present invention, vinyl monomers having primary amino groups, secondary amino groups, tertiary amino groups, or quaternary ammonium salts can be used one or more in combination. Furthermore, while the dissociation of primary to tertiary amino groups is suppressed at pH 7 and above, the presence of a quaternary ammonium base allows for dissociation even at pH 9 and above. Therefore, when mixed with latex at pH 10 or above, the cation function can be maintained over a wide pH range. However, primary amine groups have a high hydrogen bonding affinity to tertiary and quaternary amines, which allows for increased interaction with other components of the adhesive composition.

[0148] The content of the vinyl monomer having a cationic group (b) is not particularly limited, but if included, it is, for example, 0.01 mol% or more, preferably 0.5 mol% or more, and for example, 20 mol% or less, preferably 10 mol% or less, relative to the total monomers constituting the acrylamide polymer. When the content of vinyl monomers having cationic groups is 0.01 mol% or more, the tackiness of the latex can be suppressed when it is adsorbed by coacervation onto the surface of latex particles dispersed in water with an anionic surfactant and forms a surface coating. Preferably, it is 0.5 mol% or more. However, if it is 20 mol% or less, the aggregation between particles becomes high, which is undesirable. Furthermore, a content of vinyl monomers having cationic groups of 10 mol% or less is preferable because it tends not to shorten the degree of polymerization during manufacturing.

[0149] The vinyl monomer having an anionic group (c) is not particularly limited as long as it is a vinyl monomer having an anionic group in its molecule, but examples include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated tricarboxylic acids, unsaturated tetracarboxylic acids and their salts. Specifically, examples include unsaturated monocarboxylic acids such as (meth)acrylic acid, angelic acid, tigric acid, crotonic acid, and isocrotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, muconic acid, and citraconic acid; unsaturated tricarboxylic acids such as 3-butene-1,2,3-tricarboxylic acid, 4-pentene-1,2,4-tricarboxylic acid, and aconitic acid; or alkali metal salts such as sodium salts and potassium salts or ammonium salts of these various organic acids; sulfonic acid monomers having a vinyl group such as vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, (meth)allylsulfonic acid, and diacryloylimide; or salts such as alkali metal salts such as sodium salts and potassium salts or ammonium salts of these various organic acids. In the present invention, vinyl monomers having these anionic carboxyl groups and their salts can be used individually or in combination of two or more. Among these, unsaturated monocarboxylic acids and unsaturated dicarboxylic acids, specifically acrylic acid, 2-acrylamido-N-glycolic acid, itaconic acid and their salts, are preferred in terms of polymerizability and cost, and acrylic acid or its sodium salt is particularly preferred.

[0150] The content of the vinyl monomer having an anionic group (c) is not particularly limited, but if included, it is, for example, 0.01 mol% or more, preferably 0.5 mol% or more, and for example, 20 mol% or less, preferably 10 mol% or less, relative to the total monomers constituting the acrylamide polymer. When the polymerization component contains 0.01 mol% or more of anionic polymerizable monomer, the polyamide adsorbed on the latex exhibits a greater tackiness-suppressing effect due to the dispersibility provided by the anionic groups. On the other hand, an increase in carboxyl groups leads to stronger acidity during rubber vulcanization. Since the sulfur crosslinking reaction of rubber latex decreases in highly acidic conditions, the crosslinking of the adhesive layer tends to be reduced.

[0151] Furthermore, the water-soluble compound containing the (D-2) acrylamide structure may, from the viewpoint of processability, be a copolymer containing (d) other copolymerizable polymerizable monomers.

[0152] Other specific examples of polymerizable monomers include N-substituted lower alkylacrylamides other than (meth)acrylamides such as N-ethylacrylamide, N,N-dimethylacrylamide, and N-isopropylacrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N,N-diisopropyl(meth)acrylamide; alkylenebis(meth)acrylamides such as methylenebis(meth)acrylamide and ethylenebis(meth)acrylamide; allyl(meth)acrylamide; and N-substituted acrylamide monomers such as N,N'-dimethylacrylamide, diacetoneacrylamide, and isopropylacrylamide. Furthermore, other copolymerizable monomers containing an imide group include, for example, diacryloylimide. Preferably, alkyl(meth)acrylates and hydroxyalkyl(meth)acrylates are used.

[0153] Furthermore, other copolymerizable monomers that do not contain amide or imide groups include alkyl(meth)acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, and cyclohexyl(meth)acrylate; hydroxyalkyl(meth)acrylates such as hydroxyethyl(meth)acrylate and hydroxypropyl(meth)acrylate, and hydroxyl-containing(meth)acrylates such as glycerol(meth)acrylate; polyalkylene glycol mono(meth)acrylates such as diethylene glycol(meth)acrylate and methoxypolyethylene glycol(meth)acrylate; and ethylene glycol Examples include polyalkylene glycol di(meth)acrylates such as glycol di(meth)acrylate and diethylene glycol di(meth)acrylate; polyalkylene glycol monoether mono(meth)acrylates such as diethylene glycol monoethyl ether compound acrylates; epoxy acrylates; urethane acrylates; nitrile compound monomers such as acryloylmorpholine and (meth)acrylonitrile; olefins such as vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene, and butene; substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate; and aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, vinylpyrrolidone, and vinyloxazoline.

[0154] These other polymerizable monomers may be used individually or in combination of two or more. In particular, when a branched structure is introduced during the extension reaction of polymerization, the cured film of the adhesive composition after heat treatment has high hardness and excellent adhesion to the substrate. Therefore, it is preferable to use crosslinkable monomers containing amide groups, such as N-substituted acrylamide monomers such as methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, allyl(meth)acrylamide, N,N'-dimethylacrylamide, diacetone acrylamide, and isopropylacrylamide; crosslinkable monomers containing imide groups, such as diacryloylimide; nitrogen-free bifunctional crosslinkable monomers such as divinylbenzene, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and allyl(meth)acrylate; and nitrogen-free polyfunctional crosslinkable monomers such as pentaerythritol triacrylate, trimethylolpropane acrylate, and tetraallyloxyethane. Among these, N,N-dialkyl(meth)acrylamide and alkylenebis(meth)acrylamide are preferred, and N,N-dimethylacrylamide and methylenebis(meth)acrylamide are more preferred.

[0155] (d) These monomers used in copolymers containing other copolymerizable polymerizable monomers are not limited to these exemplified monomers. Furthermore, they are optional components, and the amount used is not particularly limited, but is generally 0.01 mol% or more, preferably 0.1 mol% to 40 mol%. For example, 0.01 mol% or more, preferably 0.1 mol% or more, and for example, 30 mol% or less, preferably 20 mol% or less.

[0156] The water-soluble compound containing the (D-2) acrylamide structure may be further modified, and may also include modified compounds obtained by crosslinking with a hydrazide compound such as hydrazine, modified compounds obtained by Mannich modification of polyacrylamide in which a portion of the acrylamide structure derived from (a)(meth)acrylamide is modified into a cation group, and modified compounds obtained by using a formaldehyde-based crosslinking agent such as glyoxal for cationic polyacrylamide such as glyoxalized polyacrylamide.

[0157] Specifically, the water-soluble compounds containing the above (D-2) acrylamide structure include: (a) a polymer consisting of (meth)acrylamide, which is nonionic polyacrylamide; a copolymer consisting of (a) (meth)acrylamide and (b) a vinyl monomer having a cationic group, which is cationic polyacrylamide; a copolymer consisting of (a) (meth)acrylamide and (c) a vinyl monomer having an anionic group, which is anionic polyacrylamide; and polymers consisting of (a) (meth)acrylamide and (b) a vinyl monomer having a cationic group, and copolymers with (c) a vinyl monomer having an anionic group, which are also called amphoteric polyacrylamide.

[0158] These water-soluble compounds containing (D-2) acrylamide structures can be obtained by reacting nonionic polyacrylamide, cationic polyacrylamide, anionic polyacrylamide containing carboxyl groups, and amphoteric polyacrylamide using known methods. For example, the production method is not particularly limited, but it can be obtained by copolymerizing a mixture of (meth)acrylamide and a cationic vinyl monomer and / or an ionic vinyl monomer by aqueous polymerization, emulsion polymerization using water and an organic solvent, suspension polymerization, etc., and the production can be carried out by various conventionally known methods such as simultaneous polymerization and continuous dropwise polymerization. For example, the copolymer can be produced by charging the monomer mixture and water, adding a persulfate such as potassium persulfate or ammonium persulfate, or a known radical polymerization initiator such as a redox polymerization initiator, and further adding a chain transfer agent as appropriate, and polymerizing under stirring at 15°C to 100°C for 0.1 to several hours. The polymerization reaction can also be stopped by adding a known polymerization arrestor such as sodium thiosulfate or sodium sulfite.

[0159] Examples of chain transfer agents include isopropyl alcohol and mercaptos (e.g., mercaptoethanol, thiourea, thioglycolic acid, mercaptopropionic acid, thiosalicylic acid, thiolactic acid, aminoethanethiol, thioglycerol, thiomalic acid, etc.). The amount of such chain transfer agent used is usually 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass, per 100 parts by mass of the total monomer weight of the compound containing the acrylamide structure having a cationic group and / or a carboxyl group.

[0160] The water-soluble compound containing the (D-2) acrylamide structure obtained in this way can be obtained in the form of an aqueous solution or an aqueous dispersion. Polyacrylamide obtained in gel form may be mechanically pulverized and then dispersed again in water before use. In use in the adhesive composition of the present invention, it is preferable to use it as an aqueous solution.

[0161] The weight-average molecular weight of the copolymerized polyacrylamide obtained in this way is, for example, 1 million or more, preferably 2 million or more, more preferably 2 million or more, for example, 15 million or less, preferably 10 million or less, and even more preferably 8 million or less. By having a weight-average molecular weight of 1 million or more of the acrylamide-containing compound, aggregation of the rubber latex particles can be suppressed more reliably, and by having a weight-average molecular weight of 15 million or less of the acrylamide-containing compound, problems such as crosslinking and gelation of the acrylamide-containing compound are not caused.

[0162] Furthermore, if the pH is typically around 3-9 and the viscosity is around 100-10000 mPa·s in a 10% by weight aqueous solution, it becomes easier to store and transport the solution in liquid form.

[0163] As the water-soluble compound containing the (D-2) acrylamide structure, commercially available nonionic, anionic, cationic, or amphoteric polyacrylamide products can be used. In particular, papermaking chemicals such as yield enhancers, water drainage enhancers, and paper strength enhancers, which are internal additives for paper, can be used.

[0164] Copolymerized polyacrylamide, a papermaking agent, can provide strength to the paper product by fixing (adsorbing) to the pulp. Adding a paper strength enhancer improves the adhesive strength between cellulose fibers that make up the paper during papermaking (Yasushi Takahata, "Utilization of Synthetic Polymers in the Papermaking Industry (Part 1)," Journal of the Japan Paper and Pulp Technology Association, 1973, Vol. 27, No. 12, p. 607). The amide group of polyacrylamide resin is highly reactive and has excellent cohesive strength due to its strong affinity with fillers through hydrogen bonding, van der Waals forces, etc. Therefore, the amide portion is a paper strength enhancing portion, and in the adhesive composition of the present invention, it is preferable to use a compound containing an acrylamide structure made of acrylamide such as (meth)acrylamide, as this improves the cohesive fracture resistance in the adhesive layer between the adhered fiber filaments.

[0165] In this way, as described above, by including (B) a polyvalent metal salt, the water-soluble compound containing the (D-2) acrylamide structure acts as a ligand and interacts with the metal ion in a coordinated structure. This increases the charge interaction cohesive force between the water-soluble compounds containing the (D-2) acrylamide structure, and also enhances the ability of the water-soluble compound component containing the (D-2) acrylamide structure to fix to the anionic groups on the surface of the organic fiber to be adhered via the (B) polyvalent metal salt, resulting in particularly good adhesion between the adhesive composition and the adherend rubber composition.

[0166] Furthermore, when polyacrylamide resins like those described above have a branched structure introduced by the action of chain-transfer substituents, they are thought to have many contact points with substrates such as fibers, improving affinity and adhesion, and resulting in excellent adhesive performance. In addition, despite their relatively high molecular weight, the branched structure allows the product to have a high solids content and low viscosity, resulting in excellent workability and drying properties, while exhibiting various characteristic properties without reducing cohesive strength.

[0167] Furthermore, the ionic groups of the anionic and cationic groups function as fixation sites on pulp fibers. Regarding the carboxyl group of the anionic group, due to its anionic nature, when a (B) polyvalent metal salt such as pando sulfate is added, the polyvalent metal salt acts as a fixative, resulting in good fixation to the fibers. Cationic polymer electrolytes generally have inferior thermal stability compared to anionic and nonionic polymers, and due to their cationic nature, they are used as flocculants and in paper fixing processes (Machida, Makoto, A Few Problems Regarding Water-Soluble Polymers, Journal of Synthetic Organic Chemistry, 1975, Vol. 33, No. 3, p. 156). Furthermore, polyamides possessing anionic and cationic groups have an isoelectric point on the surface of a polyamide resin, such as a nylon fiber material used as the adherend in the examples of the present invention, due to the hydrolysis of some amide bonds, resulting in a surface state with both cationic and anionic properties. Therefore, as a compound to dye or fix to the surface, amphoteric polyamides with an isoelectric point near neutral can be considered as fixing agents for fiber surfaces. In one embodiment, the tackiness of the latex can be suppressed by coating the anionic emulsifier of rubber latex with the cationic groups of amphoteric polyacrylamide and dispersing it with the anionic groups of amphoteric polyamide. Furthermore, even nonionic polyacrylamides composed of (a)(meth)acrylamide are not completely nonionic, but rather possess a slight degree of zwionicity, because some of the acrylamide structure decomposes to form anionic and cationic groups.

[0168] These nonionic polyacrylamides are preferable because they are inexpensive and have some zwitterionic properties that allow them to adhere. Furthermore, amphoteric polyacrylamides have the ability to adhere to rubber latex while also adhering to the substrate. Moreover, even when added in large quantities, they have the ability to self-adhere even if there is an excess of cationic groups, so they do not easily thicken the liquid and can be used effectively.

[0169] <(E)amine compounds> One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (E) an amine compound.

[0170] Preferably, the (E) amine compound is a polyfunctional amine compound having two or more primary to tertiary amino groups. When the (E) amine compound is a polyfunctional amine compound having two or more primary to tertiary amino groups, the adhesion between the organic fibers and the coated rubber composition can be improved when the adhesive composition is used on organic fibers. Examples of the (E) amine compound include ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, phenylenediamine, metaxylenediamine, diethylenetriamine, triethylenetetramine, triaminopropane, or amino group-containing resins having amino groups such as polyvinylamine, polyethyleneimine, polyallylamine, and polylysine.

[0171] 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 can be determined, for example, by a known viscosity method. If the molecular weight of the amino group-containing resin is too high, the viscosity may become too high due to gel crosslinking in the liquid of the adhesive composition, which may cause problems in terms of workability.

[0172] In the present invention, among these, polyethyleneimine, an amino group-containing resin, can be suitably used as the (E) amine compound. 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, commercially available polyethyleneimine reagents with an average molecular weight of approximately 600, which has a branched structure rather than being a completely linear molecule, can be used. Although polyethyleneimine is available in liquid form, it is preferable to use it as an aqueous solution when using it in the adhesive composition of the present invention.

[0173] The (E) amine compound (particularly polyethyleneimine) is emulsified by the action of an emulsifier on the (A) rubber latex surface dispersed in an aqueous solvent. Furthermore, through interactions that coordinate with metal ions similar to those used as flocculants for heavy metal ions in aqueous systems, the (B) polyvalent metal salt strengthens the protective film on the latex surface, thereby suppressing the tackiness of the rubber latex. This makes it possible to suppress the adhesion of the adhesive composition to rolls, etc., in the process of coating organic fiber cords with the adhesive composition and drying and heat-curing the adhesive, resulting in improved workability.

[0174] In this way, as described above, by including (B) a polyvalent metal salt, the (E) amine compound interacts with the metal ion to form a coordination structure through the amine's unpaired electrons, thereby increasing the charge interaction cohesive force between the polymer compounds of the (E) amine compound. At the same time, the (E) amine compound component can be fixed to the anionic groups on the surface of the organic fiber to be adhered via the (B) polyvalent metal salt to which it is coordinated, resulting in particularly good adhesion between the adhesive composition and the adherend rubber composition. Furthermore, the adhesive composition containing the (E) amine compound exhibits good adhesion to the organic fiber cord due to the effect of (B) polyvalent metal salt, which strengthens fixation to the organic fiber surface.

[0175] The content of the (E)amine compound in the total solid content of the adhesive composition (solid content) is not particularly limited, but is preferably 0.3% by mass or more, and more preferably 0.5% by mass or more. Furthermore, the content of the (E)amine compound (solid content) is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 10% by mass or less. When the adhesive composition is vulcanized with the adherend to form a compound, the sulfur component migrated from the rubber vulcanizes the rubber latex of the adhesive composition. Since the amine component has the property of promoting rubber vulcanization by sulfur, by setting the content of the (E)amine compound to 35% by mass or less, it is possible to suppress the hardening and deterioration of the physical properties of the adhesive layer without excessive crosslinking (overvulcanization) due to vulcanization.

[0176] (F) Polyvinyl alcohol One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and (F) polyvinyl alcohol.

[0177] The (F) polyvinyl alcohol is not particularly limited, and conventionally known polyvinyl alcohols can be used, such as those produced by saponifying polyvinyl acetate with an alkali, acid, ammonia water, etc.

[0178] The (F) polyvinyl alcohol may be partially saponified polyvinyl alcohol, preferably with a degree of saponification of 80 mol% or more. When the (F) polyvinyl alcohol has a degree of saponification of 80 mol% or more, the adhesion between the organic fibers and the coating rubber composition can be improved when the adhesive composition is used on organic fibers.

[0179] The degree of polymerization of (F) polyvinyl alcohol is not particularly limited as long as the polyvinyl alcohol is soluble in water, but it is preferably in the range of 100 to 10,000, and more preferably 200 to 5,000. If the molecular weight of (F) polyvinyl alcohol is 10,000 or less, it is possible to suppress the occurrence of problems where the viscosity of the adhesive composition liquid increases and the workability decreases.

[0180] The aforementioned (F) polyvinyl alcohol can be obtained in the form of a powder or an aqueous solution, but in use in the adhesive composition of the present invention, it is preferable to use it as an aqueous solution.

[0181] Furthermore, as the (F) polyvinyl alcohol, copolymers of vinyl alcohol and monomers copolymerizable with vinyl alcohol, such as ethylene-vinyl alcohol copolymers, partially saponified ethylene-vinyl alcohol copolymers, and acetoacetyl-modified polyvinyl alcohol, can be used, and in the present invention, it is particularly preferable to use (F-1) acetoacetyl-modified polyvinyl alcohol. When (F) polyvinyl alcohol is acetoacetyl-modified polyvinyl alcohol, the adhesion between the organic fiber and the coated rubber composition can be improved when the adhesive composition is used on organic fibers.

[0182] The (F-1) acetoacetyl-modified polyvinyl alcohol can be obtained by reacting a polyvinyl alcohol-based resin with diketene in a known manner. For example, the production method is not particularly limited, but it can be obtained by dispersing the polyvinyl alcohol-based resin in a solvent such as acetic acid and then adding diketene, by pre-dissolving the polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane and then adding diketene, or by contacting the polyvinyl alcohol-based resin with diketene gas or liquid diketene.

[0183] As the (F-1) acetoacetyl group-modified polyvinyl alcohol, a polyvinyl alcohol with a degree of acetoacetyl group modification of 0.05 mol% or more can usually be used. The degree of acetoacetyl group modification of the 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 degree of acetoacetyl group modification is 0.05 mol% or more, the water resistance of the adhesive layer can be made sufficient.

[0184] The commercially available (F-1) acetoacetyl group-modified polyvinyl alcohols mentioned above are not particularly limited, but examples include the Gosenex Z series manufactured by Mitsubishi Chemical Corporation, specifically Z-100, Z-200, Z-210, Z-220, Z-300, Z-320, and Z-410.

[0185] In the adhesive composition of the present invention, (F) polyvinyl alcohol, through its function as an emulsifier, coats the surface of the rubber latex having (A) an unsaturated diene, forming a composite with the rubber latex having the unsaturated diene. This coating provides an effect of suppressing the tackiness of the rubber latex having (A) an unsaturated diene.

[0186] Furthermore, the (F) polyvinyl alcohol, in particular, (F-1) acetoacetyl-modified polyvinyl alcohol, has been conventionally known as a condensing agent with various materials such as amines, hydrazides, aldehydes, and metal salts in water, and as a self-crosslinking agent by heat treatment. It has been widely used conventionally in applications such as an emulsifier for vinyl acetate emulsions, a condensing agent for coatings of coated and uncoated papers requiring water resistance, and for imparting water resistance to adhesives, binders, etc. As a result, the adhesive composition of the present invention suppresses the tackiness of rubber latex, which is measured as the mechanical stability of the adhesive liquid under shear strain, thereby suppressing the adhesion of the adhesive composition to rolls, etc., in the process of coating organic fiber cords with the adhesive composition and drying and heat curing, resulting in good workability.

[0187] Furthermore, by including (B) a polyvalent metal salt, the hydroxyl or carboxyl anionic groups of (F) polyvinyl alcohol interact with the polyvalent metal ions. The interposition of the polyvalent metal ions between the anionic groups of (F) polyvinyl alcohol and the anionic groups on the surface of the adhered organic fiber resin enhances the ability to fix to the organic fiber surface, resulting in particularly good adhesion between the adhesive composition and the adhered rubber composition.

[0188] Furthermore, in the process of coating the surface of the organic fiber cord with the adhesive composition and drying and heat-curing it, the (F-1) acetoacetyl-modified polyvinyl alcohol can be chemically crosslinked by the self-crosslinking agent during heat treatment, and if the adhesive composition contains other components, it can also chemically crosslink with those components, thereby improving the adhesion between the organic fiber and the coated rubber composition.

[0189] The content of (F) polyvinyl alcohol in the total solid content of the adhesive composition (solid content) is not particularly limited, but is preferably 0.05% by mass or more, and preferably 25% by mass or less. The content of (F) polyvinyl alcohol is 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. When the content of (F) polyvinyl alcohol is 0.05% by mass or more, its function as an emulsifier allows for the suppression of the tackiness of the rubber latex by coating the rubber latex having (A) unsaturated diene. Furthermore, when the content of (F) polyvinyl alcohol is 25% by mass or less, the amount of (F) polyvinyl alcohol contained in the adhesive composition liquid does not become too large, and the decrease in workability caused by the increased viscosity of the adhesive composition liquid can be suppressed.

[0190] <(G) Epoxide Compounds> A preferred embodiment of the adhesive composition of the present invention optionally further comprises (G) an epoxide compound. In this case, excellent adhesion and mechanical stability can be achieved even if formaldehyde and resorcinol are not included.

[0191] As the (G) epoxide compound, various compounds having at least one epoxy group in one molecule can be used. The epoxide compound acts as a crosslinking agent for the adhesive composition, enabling excellent adhesion, and also improving heat resistance, durability, strength, flexibility, electrical insulation, etc.

[0192] The (G) epoxide compound is not particularly limited, but is preferably a compound having two or more epoxy groups in one molecule, and more preferably a compound having four or more epoxy groups. When the epoxide compound has two or more epoxy groups in one molecule, it functions effectively as a crosslinking agent for the epoxy groups, and when it has four or more epoxy groups, crosslinking is performed more densely, and flexibility is also imparted. Furthermore, the epoxide compound is not particularly limited, but it is preferable that it has 10 or fewer epoxy groups per molecule. In this case, the crosslinking density does not become excessive, and toughness is also achieved.

[0193] Specifically, the (G) epoxide compound can be a reaction product of polyhydric alcohols such as diethylene glycol diglycidyl ether, polyethylene diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, or sorbitol polyglycidyl ether, with epichlorohydrin. Using these compounds as the epoxy compound can further improve the adhesion between the organic fiber cord and the rubber. Furthermore, if the (G) epoxide compound is a reaction product of polyhydric alcohols with epichlorohydrin, the adhesion between the organic fiber and the rubber can be further improved.

[0194] The (G) epoxide compound functions as a crosslinking agent and, by crosslinking with one or more components selected from the group consisting of (C) to (F) contained in the adhesive composition at nucleophilic sites, it can contribute to strengthening the adhesion between, for example, organic fibers and coated rubber compositions.

[0195] The content of the (G) epoxide compound in the total solid content of the adhesive composition (solid content) is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. It is also preferably 20% by mass or less, and more preferably 10% by mass or less. If it is 0.1% by mass or more, the adhesion between the organic fiber and the coated rubber composition will be better. If it is 40% by mass or less, it will be possible to ensure a relatively high amount of other components such as rubber latex blended into the adhesive composition, and as a result, the adhesion to the rubber to be adhered will be better.

[0196] <(H)(thermally dissociable blocked) isocyanate group-containing aqueous compound> A preferred embodiment of the adhesive composition of the present invention optionally further comprises an aqueous compound having a (H)(thermally dissociable blocked) isocyanate group. In this case, excellent adhesion and mechanical stability can be achieved even without the presence of formaldehyde and resorcinol.

[0197] The (H)(thermally dissociable blocked) isocyanate group in the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group means a thermally dissociable blocked isocyanate group or an isocyanate group. Specifically, the (thermally dissociable blocked) isocyanate group includes (a) a thermally dissociable blocked isocyanate group formed by the reaction of an isocyanate group with a thermally dissociable blocking agent to the isocyanate group, (b) an isocyanate group that has not reacted with the thermally dissociable blocking agent to the isocyanate group, (c) an isocyanate group formed by the dissociation of a thermally dissociable blocking agent from a thermally dissociable blocked isocyanate group, and (d) an isocyanate group.

[0198] The term "aqueous" in the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group indicates that it is water-soluble or water-dispersible. Furthermore, "water-soluble" does not necessarily mean completely water-soluble, but also means partially water-soluble or that it does not undergo phase separation in an aqueous solution of the adhesive composition.

[0199] The aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is preferably a water-dispersible (thermally dissociable blocked) isocyanate compound (hereinafter also simply referred to as "(H-1) component") consisting of an addition product of a polyisocyanate having an (H-1) aromatic ring and a blocking agent having one or more active hydrogen groups. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition is improved.

[0200] Here, with respect to the (H-1) component, an active hydrogen group refers to a group containing hydrogen that becomes active hydrogen (atomic hydrogen (hydrogen radical) and hydride ion (hydride)) when placed under suitable conditions. Examples of such active hydrogen groups include amino groups and hydroxyl groups.

[0201] The thermally dissociable blocking agent is not particularly limited as long as it is a blocking agent compound that protects the isocyanate group from any chemical reaction and, if necessary, allows the blocking agent to be dissociated by heat treatment to restore the isocyanate group. Specifically, in the process shown in Figure 1, it is preferable that the thermal dissociation temperature at which the heat treatment is performed for thermal curing after the adhesive treatment liquid has been applied and dried is such that the crosslinking reactivity of the isocyanate group, which has been sealed and its reactivity suppressed by the thermally dissociable blocking agent, can be restored.

[0202] Blocking agents include, but are not limited to, alcohols, phenols, active methylene compounds, oximes, lactams, and amines. Specifically, these 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; dialkyl malonates such as dimethyl malonate and diethyl malonate; active methylene compounds such as methyl acetoacetate, ethyl acetoacetate, and acetylacetone; and methyl mercaptan and dodecyl mercaptan. Examples include lucaptans; 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. Among these blocking agents, phenol, ε-caprolactam, and ketoxime are preferable because they readily provide stable thermal curing of the adhesive composition through thermal dissociation upon heating.

[0203] Furthermore, the (H-1) component specifically includes aromatic polyisocyanates or aromatic aliphatic polyisocyanates. 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), and dialkyl Examples 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; and others. Examples of aromatic aliphatic 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); and others. Other examples include modified polyisocyanates such as carbodiimides, polyols, and allophanates.

[0204] Among polyisocyanates containing these aromatic rings in their molecules, aromatic isocyanates are preferred from the viewpoint of the code convergence properties of the adhesive composition, more preferably tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or polymethylene polyphenyl polyisocyanate (polymeric MDI), and particularly preferably diphenylmethane diisocyanate (MDI). By using block bodies of methylenediphenyl isocyanates, especially block bodies of methylenediphenyl diisocyanate (also called "diphenylmethane diisocyanate"), when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition becomes even better.

[0205] Furthermore, it is more preferable that the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is an aqueous urethane compound having the (H-2)(thermally dissociable blocked) isocyanate group (hereinafter also simply referred to as "(H-2) component"). In this case as well, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition will be better. Details of the above (H-2) component will be described later for convenience of explanation.

[0206] The content of the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group in the total solid content of the adhesive composition (solid content) 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. Furthermore, the content of the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 45% by mass or less. This is because if the content of the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is 5% by mass or more, the adhesion between the organic fiber and the coated rubber composition will be better. Furthermore, if the content of the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group is 70% by mass or less, it becomes possible to ensure a relatively high amount of other components such as rubber latex blended into the adhesive composition, resulting in better adhesion to the rubber to be adhered.

[0207] In conventional adhesive compositions containing resorcinol and formaldehyde, a sea-island structure is formed in which rubber latex particles (likened to islands) are dispersed in a phenolic resin (likened to the sea) formed by the co-condensation of resorcinol and formaldehyde. This provides good adhesion between the phenolic resin coating the surface of the organic fiber and the organic fiber.

[0208] On the other hand, in one preferred embodiment of the adhesive composition of the present invention, instead of the phenolic resin obtained by the co-condensation of resorcinol and formaldehyde, the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group acts as an adhesion promoter with the following two functional effects (x) and (y). As a result, in the adhesive composition, the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group contributes to the characteristic of good adhesion between the organic fiber and the coated rubber composition.

[0209] (x) The aqueous compound is distributed near the interface between the organic fiber and the adhesive layer formed by the adhesive composition, thereby promoting the adhesion between the organic fiber and the adhesive layer. (y) A functional effect of reinforcing the adhesive layer by forming a three-dimensional network structure within the adhesive layer of the adhesive composition through crosslinking by the isocyanate group of the compound having the (thermally dissociable blocked) isocyanate group.

[0210] In one embodiment of the adhesive composition of the present invention, an example of the principle of the two functional effects (x) and (y) of the aqueous compound having the (H)(thermally dissociable blocked) isocyanate group as an adhesion promoter will be described in detail below.

[0211] <<Regarding the functional effects of (x) as an adhesion promoter>> Polyester synthetic resin materials, such as polyethylene terephthalate, which are commonly used as organic fibers, consist of flattened linear polymer chains. The surface of these polymer chains or the gaps between them have a π-electron atmosphere derived from aromatic compounds contained in the polymer chains. Furthermore, polyester has particularly fewer hydroxyl groups on its surface compared to nylon 6,6. Therefore, conventional adhesive compositions used for organic fibers made of polyester have contained molecules with a planar structure (a portion that easily diffuses into organic fibers) having aromatic π-electrons on their sides as an adhesion promoter, with the aim of dispersing the adhesive composition into the gaps between the polymer chains of the organic fiber and ensuring that the adhesive layer formed by the adhesive composition adheres closely to the surface of the polymer chains of the organic fiber.

[0212] <<Regarding the functional effects of (y) as an adhesion promoter>> In the adhesive layer containing the (H-1) component, as described above, adhesion by the adhesive composition can be strengthened by forming a covalent bond through isocyanate crosslinking between the hydroxyl group of the water-soluble compound containing the (D-2) acrylamide structure and the isocyanate from which the blocking agent has been dissociated by heat treatment.

[0213] Furthermore, as mentioned above, the particle size of the (H-1) component is preferably 0.01 to 0.50 μm. When the particle size of the (H-1) component is 0.50 μm or less, the smaller the particle size, the less likely the (H-1) component is to settle in the liquid, and the less likely it is to be dispersed unevenly in the adhesive layer. On the other hand, if the aqueous urethane compound has an (H-2)(thermally dissociable blocked) isocyanate group, its high water solubility makes it less likely for components to settle in the adhesive composition liquid, and even when stored at rest, there is less non-uniformity of components, which is preferable as it ensures stable adhesion over time.

[0214] <<Thermal dissociation blocking agent, aqueous urethane compound>> The thermally dissociable blocking agent for component (H-2) is not particularly limited as long as it is a blocking agent compound that protects the isocyanate group from any chemical reaction and, if necessary, allows the blocking agent to be dissociated by heat treatment to restore the isocyanate group. Specific examples of the thermally dissociable blocking agent include the same compounds as the blocking agent described above for component (H-1), and preferably 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 phthalimide. Examples include: lactams such as δ-valerolactam; caprolactams such as ε-caprolactam; active methylene compounds such as dialkyl malonates such as diethylmalonate and dimethylmalonate, acetylacetone, and alkyl acetoacetate; oximes such as acetoxime, methylethylketoxime, and cyclohexanone oxime; basic nitrogen compounds such as 3-hydroxypyridine, 1,2-pyrazole, 3,5-dimethylpyrazole, 1,2,4-triazole, diisopropylamine, and N,N'-diphenylformamidine, as well as acidic sodium sulfite.

[0215] Among these blocking agents, phenol, ε-caprolactam, and ketoxime are preferable because they readily provide stable thermal curing of the adhesive composition through thermal dissociation upon heating.

[0216] Here, "aqueous" in the aqueous urethane compound means that it is water-soluble or water-dispersible. Furthermore, "water-soluble" does not necessarily mean completely water-soluble, but also means partially water-soluble, or that it does not undergo phase separation in an aqueous solution of the adhesive composition.

[0217] The urethane compound in the aqueous urethane compound is a compound having a covalent bond formed between the nitrogen of the amine and the carbon of the carbonyl group, and refers to a compound represented by the following general formula (2). [ka] In formula (2) above, R and R' represent hydrocarbon groups.

[0218] The molecular weight of the aqueous urethane compound having the (H-2)(thermally dissociable blocked) isocyanate group is not particularly limited as long as it can maintain its aqueous properties, and is preferably a number average molecular weight of 1,500 to 100,000, and particularly preferably 9,000 or less.

[0219] As mentioned above, the method for synthesizing the (H-2) component is not particularly limited and can be a known method such as the method described in Japanese Patent Publication No. 63-51474.

[0220] <<Preferred Embodiments of Aqueous Urethane Compounds Having (H-2)(Thermally Dissociable Blocked) Isocyanate Groups>> A preferred embodiment of the (H-2) component is a reaction product obtained by mixing (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 hydrophilic group that is anionic, cationic, or nonionic, in a predetermined mixing ratio and reacting them, wherein the proportion of (thermally dissociable blocked) isocyanate groups 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. Here, the respective mixing ratios of (α), (β), (γ), and (δ) to the total amount are as follows: (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. In this case, when the adhesive composition is used on organic fibers, the adhesion between the organic fibers and the coated rubber composition becomes even better. This is because such (H-2) components have the advantage of increasing the self-water solubility of the urethane compound because they have both a moiety consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic moiety having a hydrophilic group.

[0221] The organic polyisocyanate compound having 3 to 5 functional groups (α) 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, and may also be other aliphatic, alicyclic, or heterocyclic polyisocyanate compounds and their oligomers. This is because the (H-2) component, which is the reaction product after reacting such an organic polyisocyanate compound having 3 to 5 functional groups (α) 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.

[0222] 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, lysine diisocyanate, etc., while examples of alicyclic polyisocyanate compounds include cyclobuta Examples include 1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1,3-(isocyanatomethyl)cyclohexane, and heterocyclic polyisocyanate compounds such as 1,3,5-tris(2'- Examples of aromatic polyisocyanate compounds include tolylene diisocyanate adducts of hydroxyethyl)isocyanuric acid, m-phenylenediisocyanate, p-phenylenediisocyanate, 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, tris(4-isocyanatophenyl ester) thiophosphate, 3-isopropenyl-α',α'-dimethylbenzyl isocyanate and oligomer mixtures thereof, or modified products of these polyisocyanate compounds such as carbodiimides, polyols, and allophanates.

[0223] Among these, aromatic polyisocyanate compounds are preferred, and particularly preferred are methylenediphenyl polyisocyanate and polyphenylene polymethylene polyisocyanate. In particular, polyphenylene polymethylene polyisocyanate with a number average molecular weight of 2,000 or less is preferred, and polyphenylene polymethylene polyisocyanate with a number average molecular weight of 1,000 or less is particularly preferred. This is because the (H-2) component, which is the reaction product after reacting such organic polyisocyanate compounds having 3 to 5 (α) 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 organic fibers.

[0224] The compounds having two to four active hydrogen groups and a number-average molecular weight of 5,000 or less are not particularly limited, but specifically include compounds selected from the group consisting of (i) to (vii) below. (i) Polyhydric alcohols having 2 to 4 hydroxyl groups and a number-average molecular weight of 5,000 or less, (ii) Polyhydric amines having two to four primary and / or secondary amino groups and a number-average molecular weight of 5,000 or less, (iii) Amino alcohols having two to four primary and / or secondary amino groups and a hydroxyl group, with 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 two to four 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. Polyhydric amines, polyhydric phenols, and C2-C4 alkylene oxide polyadducts of amino alcohols, C2-C4 alkylene oxide polyadducts of polyhydric alcohols of C3 or more, C2-C4 alkylene oxide copolymers, or C3-C4 alkylene oxide polymers.

[0225] Here, with respect to the (H-2) component, the active hydrogen group refers to a group containing hydrogen that becomes active hydrogen (atomic hydrogen (hydrogen radical) and hydride ion (hydride)) when placed under suitable conditions. Examples of the active hydrogen group include an amino group and a hydroxyl group.

[0226] The compounds having (δ) at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group are not particularly limited, but examples include taurine, N-methyl taurine, N-butyl taurine, aminosulfonic acids such as sulfanilic acid, glycine, alanine, and other aminocarboxylic acids.

[0227] The method for synthesizing the (H-2) component by mixing and reacting (α), (β), (γ), and (δ) is not particularly limited, but can be a known method such as the method described in Japanese Patent Publication No. 63-51474.

[0228] <<Another preferred embodiment of an aqueous urethane compound having an (H-2)(thermally dissociable blocked) isocyanate group>> Another preferred embodiment of the (H-2) component is a reaction product obtained by mixing (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) containing an active hydrogen group, in a predetermined mixing ratio, and reacting them, wherein the proportion of (thermally dissociable blocked) isocyanate groups 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. Here, the respective mixing ratios of (α), (β), (γ), (δ), and (ε) to the total amount are as follows: (α) is 40% by mass or more and less than 85% by mass; (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; (δ) is 5% by mass or more and 35% by mass or less; and (ε) is more than 0% by mass and 45% by mass or less. This is because such (H-2) components have the advantage of increasing the self-water solubility of the urethane compound, as they possess both a moiety consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic moiety having a hydrophilic group.

[0229] Here, the compounds comprising (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 are as described in the above-mentioned <<Preferred Embodiments of Aqueous Urethane Compounds Having (H-2) (Thermally Dissociable Blocked) Isocyanate Groups>>, except for the mixing ratio.

[0230] The method for synthesizing the (H-2) component by mixing and reacting (α), (β), (γ), (δ), and (ε) is not particularly limited, but can be a known method such as the method described in Japanese Patent Publication No. 63-51474.

[0231] <<Another preferred embodiment of an aqueous urethane compound having an (H-2)(thermally dissociable blocked) isocyanate group>> Another preferred embodiment of the (H-2) component is the following general formula (1): [ka] [In formula (1), A is a residue from an organic polyisocyanate compound in which the active hydrogen group has been removed. X is a polyol compound having 2 to 4 hydroxyl groups and a number-average molecular weight of 5,000 or less, from which the active hydrogen group has been removed. Y is a residue from which the active hydrogen group has been removed from a thermally dissociable blocking agent. Z is a residue from which the active hydrogen group has been removed from a compound having at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain. n is an integer between 2 and 4, p+m is an integer between 2 and 4 (m≧0.25). This is characterized by being represented as [represented by]. In this case as well, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coated rubber composition becomes even better. This is because the (H-2) component has the advantage of increasing the self-water solubility of the urethane compound because it has both a part consisting of a (thermally dissociable blocked) isocyanate group and a hydrophilic part having a hydrophilic group.

[0232] Here, the organic polyisocyanate compound, represented by A in general formula (1), which is the residue from which the active hydrogen group of the organic polyisocyanate compound has been removed, preferably contains an aromatic ring. This is because the (H-2) component is more easily dispersed in the gaps between the polymer chains of the organic fiber.

[0233] While not particularly limited, specific examples include methylenediphenyl polyisocyanate and polyphenylene polymethylene polyisocyanate. Polyphenylene polymethylene polyisocyanate with a number average molecular weight of 6,000 or less is preferred, and polyphenylene polymethylene polyisocyanate with a number average molecular weight of 4,000 or less is particularly preferred.

[0234] The polyol compound having two to four hydroxyl groups and a number-average molecular weight of 5,000 or less, from which the active hydrogen group of the residue obtained by removing the active hydrogen group of the polyol compound having two to four hydroxyl groups, which is X in general formula (1), is not particularly limited, but specifically, examples include compounds selected from the group consisting of (i) to (vi) below. (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, with 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 having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less, and copolymers thereof with other vinyl monomers. (v) 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. (vi) Polyether polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 5,000 or less. Polyhydric amines, polyhydric phenols, and amino alcohols C2-C4 alkylene oxide polyadducts, C2-C4 alkylene oxide polyadducts of polyhydric alcohols with a capacity of 3 or more C3, C2-C4 alkylene oxide copolymers, or C3-C4 alkylene oxide polymers.

[0235] The (H-2) component is not particularly limited, but commercially available products such as Elastone BN27, BN77, and BN11 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. can also be used. Among these, Elastone BN77 is preferred.

[0236] <Method for manufacturing adhesive composition> The adhesive composition of the present invention is characterized by comprising (A) a rubber latex having an unsaturated diene, (B) a polyvalent metal salt, and one or more components selected from the group consisting of (C) to (F) below, and preferably further comprising one or more components selected from the group consisting of (G) to (H) below. (C) Aqueous component having multiple phenolic hydroxyl groups in the molecule (D) Water-soluble components containing an amide bond structure (E) Amine compounds (F) Polyvinyl alcohol (G) Epoxide compound Aqueous compounds having (H)(thermally dissociable blocked) isocyanate groups

[0237] In preparing the adhesive composition, the following can be mixed in any order: (A) rubber latex having an unsaturated diene, (B) polyvalent metal salt, (C) aqueous component having multiple phenolic hydroxyl groups in the molecule, (D) water-soluble component containing an amide bond structure, (E) amine compound, and (F) polyvinyl alcohol.

[0238] While not particularly limited, a preferred order of addition for the components to be included in the adhesive composition is as follows: (B) polyvalent metal salt, (C) aqueous component having multiple phenolic hydroxyl groups in the molecule, (D) water-soluble component containing an amide bond structure, (E) amine compound, (F) polyvinyl alcohol, (A) rubber latex having an unsaturated diene, (G) epoxide compound, and (H) aqueous compound having a (thermally dissociable blocked) isocyanate group. The reason for this is that when (B) polyvalent metal salts are mixed with components (C) to (F), they form a polyionic complex, which makes them more easily fixed by the anionic groups on the surface of the organic fibers of the adherend and the anionic groups of the emulsifier on the surface of the rubber latex.

[0239] Furthermore, although not particularly limited, in one embodiment of the adhesive composition of the present invention, if the components to be included in the adhesive composition include (B) a polyvalent metal salt and (C) an aqueous component having multiple phenolic hydroxyl groups in its molecule, it is preferable to add (C) the aqueous component having multiple phenolic hydroxyl groups in its molecule, similarly diluted with deionized water or the like, to (B) the polyvalent metal salt, preferably diluted to a solid content concentration of 20% by mass or less, to the mixture, stir at room temperature, and allow it to stand for 8 hours or more, although this is not particularly limited. The reason for this is that when (B) polyvalent metal salts are mixed with (C) aqueous components that have multiple phenolic hydroxyl groups in their molecules, the action of polyvalent metal ions such as copper and iron causes the (C) component to oxidize and the pH of the solution to change. However, allowing the resulting polyion complex to stand until it stabilizes allows it to be easily fixed by the anionic groups on the surface of the organic fibers and the anionic groups of the emulsifier on the surface of the rubber latex.

[0240] In the adhesive composition of the present invention, the mixed mass ratio of (A) rubber latex having an unsaturated diene and (C) to (F) aqueous components [(A):(C) to (F) total] (on a solid content basis) is not particularly limited, but is preferably in the range of 100:0.1 to 100:30, and more preferably in the range of 100:0.2 to 100:25. If the mixing mass ratio is 100:0.1 or more (and 1000 or less as the ratio value), a rubber latex having an unsaturated diene (A) can be used as a core, and a film of microcapsules of the aqueous components (C) to (F) can be formed around it, and an adhesive layer with sufficient strength can also be obtained. Further, if the mixing mass ratio is 100:30 or less (and 3.3 or more as the ratio value), a rubber latex having an unsaturated diene (A) can be used as a core, and the film of microcapsules of the aqueous components (C) to (F) formed around it does not become too thick. When the coated rubber composition, which is an adherend of organic fibers, and the adhesive composition are co-vulcanized and adhered, the coated rubber composition as the adherend and the rubber latex having an unsaturated diene (A) are well compatible. As a result, the initial process of adhesion between the coated rubber composition as the adherend and the adhesive composition proceeds preferably.

[0241] In the mixing of the rubber latex having an unsaturated diene (A) and the aqueous components (C) to (F), a known water-soluble material that can strengthen the film composed of the aqueous components (C) to (F) can be used in combination with a normal coacervate. For example, gum arabic, carrageenan, CM Cs, organic salts, or electrolyte substances composed of inorganic salts excluding the above-mentioned polyvalent metal salts (B), such as salts having a monovalent cation like sodium chloride, potassium chloride, ammonium chloride, salts having an anion like sulfate, phosphate, carbonate, acetate can be used. Further, a water-soluble liquid substance in which the film-forming material dissolves less than water, such as alcohols like ethanol and propanol, or water-soluble polymers such as an isobutylene-maleic anhydride ring-opening copolymer salt can also be used.

[0242] In the adhesive composition of the present invention, the mixing mass ratio [(B): total of (C) to (F)] (in terms of solid content) of the polyvalent metal salt (B) and the aqueous components (C) to (F) is not particularly limited, but it is preferably in the range of 0.001:100 to 40:100, more preferably in the range of 0.01:100 to 35:100, and even more preferably in the range of 0.1:100 to 30:100. If the mixing mass ratio is 0.001:100 or more (if the ratio value is 0.00001 or more), due to the effect of the polyion complex of (B) polyvalent metal salt and the aqueous components of (C) to (F), the charge interaction inside the film of the microcapsules of the aqueous components of (C) to (F) can be strengthened, and an adhesive layer with sufficient strength can also be obtained. Also, if the mixing mass ratio is 40:100 or less (if the ratio value is 0.4 or less), the aggregating power of the components of (C) to (F) by (B) polyvalent metal salt becomes too large, suppressing the thickening or gelation of the aqueous solution of the adhesive composition, and the workability of applying the organic fiber becomes good.

[0243] In one embodiment of the adhesive composition of the present invention, when (G) an epoxide compound is included in the components included in the adhesive composition, although it is not particularly limited, with respect to the mass consisting of all the components of the adhesive composition of the present invention, the mixing mass ratio [(G): total solid content mass of the adhesive composition] (in terms of solid content) with (G) an epoxide compound is preferably in the range of 0.1:100 to 20:100, more preferably in the range of 0.5:100 to 10:100, and even more preferably in the range of 0.7:100 to 5:100. If the mixing mass ratio is at least 0.1:100 (if the ratio value is at least 0.001), the effect of (G) an epoxide compound as a crosslinking agent in the adhesive composition can be easily obtained, and the crosslinking agent can sufficiently maintain the fracture resistance of the adhesive layer and prevent the decrease in adhesiveness under strain. Also, if the mixing mass ratio is 10:100 or less (if the ratio value is 0.1 or less), the curing of the adhesive composition due to excessive crosslinking is less, and under the strain input during tire running, the severity of the adhesive composition layer can be maintained, and the deterioration of the adhesive layer of the organic fiber coated with the adhesive composition under strain or the strength of the organic fiber cord can be suppressed, which is good.

[0244] In one embodiment of the adhesive composition of the present invention, if an aqueous compound having a (H)(thermally dissociable blocked) isocyanate group is included as a component in the adhesive composition, it is not particularly limited, but the mixed mass ratio of the aqueous compound having a (H)(thermally dissociable blocked) isocyanate group [(H): total solid content mass of the adhesive composition] (in terms of solid content) to the total mass of all components of the adhesive composition of the present invention is preferably in the range of 0.1:100 to 70:100, more preferably in the range of 1:100 to 60:100, and even more preferably in the range of 5:100 to 50:100. If the aforementioned mixing mass ratio is 0.1:100 or higher (a ratio value of 0.001 or higher), the effect of the aqueous compound having a (H)(thermally dissociable blocked) isocyanate group as a crosslinking agent in the adhesive composition is easily obtained, and the crosslinking agent can sufficiently maintain the fracture resistance of the adhesive layer, preventing a decrease in adhesion under strain. Furthermore, if the aforementioned mixing mass ratio is 70:100 or lower (a ratio value of 0.7 or lower), there is less hardening of the adhesive composition due to excessive crosslinking, the rubbing properties of the adhesive composition layer can be maintained under strain input during tire driving, and deterioration of the strength of the adhesive layer of organic fibers coated with the adhesive composition, or of the organic fiber cord, under strain is suppressed, which is desirable.

[0245] Furthermore, components (A) to (H) of the adhesive composition of the present invention are preferably aqueous. This is because water, which causes less environmental pollution, can be used as a solvent.

[0246] [Organic fiber materials] By coating the surface of an organic fiber, such as an organic fiber made of nylon resin, polyester resin, aromatic polyamide resin, or acrylic resin, with the adhesive composition configured as described above, and then subjecting it to appropriate heat treatment, an adhesive layer made of the adhesive composition is coated onto the surface of the organic fiber (resin substrate), thereby producing an organic fiber material that has undergone adhesive treatment.

[0247] The organic fiber material of the present invention comprises organic fibers and an adhesive layer covering the surface of the organic fibers, wherein the adhesive layer is made of the above-mentioned adhesive composition. This makes it possible to produce an organic fiber material with excellent durability while ensuring environmental friendliness and workability. Particularly preferably, the material of the organic fiber is nylon resin, polyester resin, aromatic polyamide resin, or acrylic resin, and among these, it is preferable that the material of the organic fiber is nylon resin or polyester resin, and particularly preferable that it is nylon resin. Organic fibers made of nylon resin have anionic groups due to oxidation of the fiber surface or hydrolysis of the amide bonds of the polymer, so the effect of the cationic charge of (B) polyvalent metal salt is increased, and the adhesion is further improved.

[0248] Methods for coating the surface of the organic fibers with the adhesive composition include immersing the organic fibers (particularly organic fiber cords) in the adhesive composition, applying the adhesive composition with a brush or the like, and spraying the adhesive composition. A suitable method can be selected as needed. The method for coating the surface of the organic fibers with the adhesive composition is not particularly limited, but when coating the surface of the organic fibers with the adhesive composition, it is preferable to dissolve the adhesive composition in various solvents to reduce its viscosity, as this facilitates coating (immersion, application, spraying, etc.). Furthermore, it is environmentally preferable that the solvent used to reduce the viscosity of the adhesive composition mainly consists of water.

[0249] Furthermore, the solution concentration of the adhesive composition impregnated into the organic fibers is not particularly limited, but is preferably 5.0% by mass or more and 25.0% by mass or less, and more preferably 7.5% by mass or more and 20.0% by mass or less, based on the solid content relative to the mass of the organic fibers.

[0250] Here, the thickness of the adhesive layer made by 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.

[0251] Furthermore, when the organic fiber-rubber composite of the present invention is applied to a tire, the adhesive durability under tire rolling tends to decrease as the amount of adhesive composition applied during the bonding process increases. This is because the adhesive composition at the interface of the adhered fiber material is relatively small in deformation due to the high rigidity of the fiber material and the resulting stress from strain, but the deformation due to strain increases as the distance from the interface increases. Compared to the adhered rubber material, the adhesive composition contains a large amount of thermosetting condensates, making it hard and brittle, which makes it prone to increased 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.

[0252] The organic fiber is preferably an organic fiber cord formed by twisting together multiple filaments. When the organic fiber is an organic fiber cord formed by twisting together multiple filaments, it is suitable for reinforcing rubber articles such as tires and conveyor belts. Furthermore, when the organic fiber is an organic fiber cord, it is preferable that the adhesive layer in the organic fiber material is 0.5 to 6.0% by dry mass of the mass of the organic fiber cord. By setting the dry mass of the adhesive layer within this range, appropriate adhesion can be ensured. The organic fiber cord will be described in detail below.

[0253] Organic fibers coated with the adhesive composition can be dried, heat-treated, and subjected to other treatments, similar to the organic fiber material described above.

[0254] The organic fiber material, in which an adhesive composition is coated onto the surface of organic fibers, is preferably dried at a temperature of, for example, 100°C to 210°C, and then subsequently subjected to heat treatment. This heat treatment is preferably carried out at a temperature above the glass transition temperature of the polymer of the organic fiber (resin substrate), preferably above the melting temperature of the polymer - 70°C and below the melting temperature - 10°C. This is because below the glass transition temperature of the polymer, the molecular mobility of the polymer is poor, and the adhesion-promoting components in the adhesive composition and the polymer cannot interact sufficiently, resulting in insufficient bonding strength between the adhesive composition and the organic fiber. Such organic fibers may be pre-treated by electron beam, microwave, corona discharge, plasma treatment, etc.

[0255] [Rubber products] The adhesive composition of the present invention described above can be suitably used for reinforcing various rubber articles. The rubber articles of the present invention are characterized by being reinforced with the above-mentioned organic fiber material. This makes it possible to produce rubber articles with excellent durability while ensuring environmental friendliness and workability. Examples of such rubber articles of the present invention include tires, conveyor belts, belts, hoses, air springs, and the like.

[0256] [Organic fiber-rubber composite] The organic fiber-rubber composite of the present invention is a composite of organic fibers and rubber, characterized in that the organic fibers are coated with the above-mentioned adhesive composition. This makes it possible to obtain good adhesion without using resorcinol, and to produce an organic fiber-rubber composite with good environmental friendliness and workability. The adhesive composition of the present invention is particularly excellent in adhesion between organic fibers such as organic fiber cords and the coating rubber composition.

[0257] Next, the organic fiber-rubber composite of the present invention will be described in detail with reference to Figure 2. Figure 2 is a schematic cross-sectional view showing an example of an organic fiber cord-rubber composite of the present invention. In the organic fiber-rubber composite 31 shown in Figure 2, the outer surface in the radial direction of the organic fiber cord 1 is covered with an adhesive layer 32 made of the adhesive composition 2 of the present invention. The organic fiber cord 1 is then bonded to the covering rubber composition 33 located further outward in the radial direction via the adhesive 32 made of the adhesive composition 2, thereby forming the organic fiber-rubber composite 31 of the present invention.

[0258] In addition to the organic fiber cord-rubber composite described above, the reinforcing material for rubber articles using the adhesive composition of the present invention can also take the form of short fibers, nonwoven fabrics, and the like.

[0259] <Organic fiber cord> An example of the aforementioned organic fiber is an organic fiber cord, which is used to reinforce the strength of rubber articles such as tires. When using the organic fiber cord as a reinforcing material, first, the spun organic fiber filament is twisted to form the organic fiber cord. Then, the organic fiber cord is embedded in the rubber covering the organic fiber cord using an adhesive composition and vulcanized to bond it, thereby creating an organic fiber-rubber composite. This organic fiber-rubber composite can then be used as a reinforcing member for rubber articles such as tires.

[0260] The material of the organic fiber is not particularly limited, but examples include polyester fibers, nylon resin fibers such as 6-nylon, 6,6-nylon, and 4,6-nylon (aliphatic polyamide fibers), protein fibers such as artificial fibroin fibers, polyketone fibers, aromatic polyamide fibers represented by polynonameethylene terephthalamide and paraphenylene terephthalamide, acrylic fibers, carbon fibers, and cellulose fibers represented by rayon and lyocell. Among these, polyester, 6-nylon, and 6,6-nylon are preferred, and 6,6-nylon is particularly preferred.

[0261] The material of the polyamide fiber is a polymer having an amide bond in the main chain. More specifically, 80% or more of the bonding modes of the repeating units in the main chain are of the amide bond type. Examples of the polyamide include, but are not particularly limited to, dicarboxylic acids such as adipic acid, sebacic acid, terephthalic acid, etc., and diamines such as hexamethylenediamine, nonanediamine, methylpentanediamine, p-phenylenediamine, m-phenylenediamine, etc., which are obtained by condensation through an amide bond reaction. The most representative aliphatic polyamide is 6,6-nylon.

[0262] The organic fiber cord is preferably an organic fiber cord formed by twisting a plurality of single fiber filaments, particularly for the purpose of reinforcing rubber articles such as tires and conveyor belts. Also, the organic fiber cord is preferably an organic fiber cord formed by twisting an upper-twisted single fiber filament and a lower-twisted single fiber filament. In this case, the fiber thickness of the organic fiber cord preferably ranges from 100 dtex to 5000 dtex. Also, in the tire of the present invention, the lower twist number is preferably 10 to 50 turns / 10 cm. Also, in the tire of the present invention, the upper twist number is preferably 10 to 50 turns / 10 cm. When the organic fiber cord is formed by applying lower and upper twists and the fiber thickness of the twisted cord is 100 dtex to 5000 dtex, and the twist numbers for twisting are such that the lower twist number is 10 to 50 turns / 10 cm and the upper twist number is 10 to 50 turns / 10 cm, it is more suitable for reinforcing rubber articles such as tires and conveyor belts.

[0263] In the present invention, it is preferable that the organic fiber is a tire cord of 66 nylon with a twist structure of 1400 dtex / 2, an upper twist number of 39 turns / 10 cm, and a lower twist number of 39 turns / 10 cm, and the adhesive composition is adhered to this tire cord, which is an organic fiber-rubber composite.

[0264] <<Coating Rubber Composition of Organic Fiber-Rubber Composite>> The coated rubber composition constituting the organic fiber-rubber composite of the present invention preferably contains 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 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 synthetic rubbers are preferred. Furthermore, these rubber components may be used individually or in combination of two or more.

[0265] <<Method for manufacturing organic fiber-rubber composites>> The organic fiber-rubber composite of the present invention is manufactured by coating an organic fiber, such as an organic fiber cord, with the adhesive composition of the present invention to form an adhesive layer, and then co-vulcanizing and bonding the rubber latex having (A) unsaturated diene in the adhesive composition with the rubber component in the coating rubber composition that is the adherend to the organic fiber.

[0266] Finally, the organic fibers coated with the adhesive composition are bonded together by co-vulcanizing the rubber latex containing (A) unsaturated diene in the adhesive composition with the rubber component in the coating rubber composition that is the adherend of the organic fibers.

[0267] For co-vulcanization of the rubber component in the coated rubber composition, for example, tillarium polysulfide compounds such as sulfur, tetramethyltillarium disulfide, and dipentamethylenethillarium tetrasulfide, and organic vulcanizing agents such as 4,4-dithiomorpholin, p-quinone dioxime, p,p'-dibenzoquinone dioxime, and cyclic sulfur imide can be used. Among these, sulfur is preferred. Furthermore, various compounding agents such as fillers, vulcanization accelerators, antioxidants, and softeners commonly used in the rubber industry, such as carbon black, silica, and aluminum hydroxide, can be appropriately added to the rubber component in the coated rubber composition.

[0268] Furthermore, it goes without saying that the adhesive composition of the present invention also provides an adhesive effect in bonding methods in which a vulcanizing agent contained in a substrate of synthetic organic fiber material such as organic fibers and / or a substrate of a coated rubber composition migrates to the adhesive composition, and the adhesive composition is crosslinked by the migrated vulcanizing agent.

[0269] [tire] The tire of the present invention uses the above-mentioned organic fiber-rubber composite. This makes it possible to obtain good adhesion without using resorcinol, resulting in a tire with good environmental performance and productivity.

[0270] In the tire of the present invention, the above-mentioned organic fiber-rubber composite can be used, for example, as a carcass, belt, belt reinforcing layer, flipper, or other reinforcing layer around the belt.

[0271] The tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has undergone a pre-vulcanization process, and then further vulcanizing it. In addition, the tire of the present invention uses an organic fiber cord treated with the above-mentioned adhesive composition in some part of the tire, but other components are not particularly limited and known components can be used. Furthermore, the tire of the present invention is preferably a pneumatic tire, and as the gas to fill this pneumatic tire, in addition to ordinary air or air with adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used.

[0272] Furthermore, the adhesive composition, organic fiber material, and organic fiber-rubber composite of the present invention described above can be applied not only to the aforementioned tires but also to all rubber articles such as conveyor belts, belts, hoses, and air springs. [Examples]

[0273] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by the following examples.

[0274] <(A) Rubber latex containing unsaturated dienes> Comparative Example 1~ 7、9~ 14 and Example 1~ 3、5~ In 29, as (A) rubber latex having an unsaturated diene, vinylpyridine-styrene-butadiene copolymer latex was prepared and used in accordance with Comparative Example 1 described in Japanese Patent Publication No. 9-78045 as follows.

[0275] In a 5-liter autoclave purged with nitrogen, 130 parts by mass of deionized water and 4.0 parts by mass of potassium rosinate as an emulsifier were charged and dissolved. To this, a monomer mixture consisting of 15 parts by mass of vinylpyridine monomer, 15 parts by mass of styrene, and 70 parts by mass of butadiene, along with 0.60 parts by mass of t-dodecyl mercaptan as a chain transfer agent, was charged and emulsified. The mixture was then heated to 50°C, and 0.5 parts by mass of potassium persulfate as a polymerization initiator was added to start polymerization. After the reaction rate of the monomer mixture reached 90%, 0.1 parts by mass of hydroquinone was added to stop the polymerization. Next, unreacted monomers were removed under reduced pressure to obtain a vinylpyridine-styrene-butadiene copolymer latex with a solid content of 41% by mass.

[0276] (B) Polyvalent metal salts In Comparative Examples 2 to 4 and each of the Examples below, the following water-soluble polyvalent metal salts (B-1, B-2, B-3) were used as (B) polyvalent metal salts, and the aqueous solutions thereof were used to prepare the adhesive compositions.

[0277] Here, as polyvalent metal salt (B-1), the product name "Copper(II) gluconate" manufactured by Tokyo Chemical Industry Co., Ltd. was used; as polyvalent metal salt (B-2), the product name "Copper(II) acetate monohydrate" manufactured by Kanto Chemical Co., Ltd. was used; and as polyvalent metal salt (B-3), the product name "Iron(II) chloride tetrahydrate" manufactured by Nacalai Tesque Co., Ltd. was used. These were dissolved in deionized water by stirring to a solid content concentration of 0.5% by mass, and this aqueous solution was used to prepare the adhesive composition.

[0278] <(C) Aqueous component having multiple phenolic hydroxyl groups within the molecule> Comparative Example 5~ 7 and Examples 1~ 3 In 13-29, (C) is an aqueous component having multiple phenolic hydroxyl groups in the molecule, such as water-soluble polyphenol (C-1). of Used.

[0279] Here, as the water-soluble polyphenol (C-1), we used (C-1-1) a partially desulfonated lignin sulfonate with a reduced degree of sulfonation, traded as "Lignin (Alkali)" by Tokyo Chemical Industry Co., Ltd., (C-1-2) kraft lignin, traded as "Lignin, alkali" by Sigma-Aldrich Co., LLC, and (C-1-3) condensed tannin, traded as "Mimosa" by Kawamura Trading Co., Ltd. These solid powder polyphenols were dissolved in deionized water to produce an aqueous solution with a solid content concentration of 10% by mass, and this aqueous solution was used in the preparation of the adhesive composition.

[0281] <(D) Water-soluble components containing an amide bond structure> In Comparative Examples 9-12, Examples 5-10, 13-22, and 25-28 below, (D) as the water-soluble component containing an amide bond structure, a water-soluble component containing a peptide structure (D-1) and a water-soluble compound containing an acrylamide structure (D-2) were used.

[0282] Here, as the water-soluble component (D-1) containing a peptide structure, (D-1-1) a hydrolyzed polypeptide derived from milk, traded as "Promis HYDOROMILK" (solid content concentration 30% by mass) manufactured by Seiwa Chemical Co., Ltd., and (D-1-2) an aqueous solution of "High-Grade Gelatin" (solid powder) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., traded as pigskin gelatin, were used in the preparation of the adhesive composition. Regarding (D-1-2) pig skin gelatin, an aqueous solution with a solid content concentration of 5% by mass was prepared using deionized water and used. However, pig skin gelatin can also be dissolved by adding it to deionized water heated to 80°C and stirring if necessary.

[0283] Furthermore, as the water-soluble compound (D-2) containing an acrylamide structure, (D-2-1) a nonionic polyacrylamide, trade name "DS4399" (20% solid content aqueous solution) manufactured by Seikoh PMC Co., Ltd., and (D-2-2) an amphoteric polyacrylamide having cationic and anionic groups, trade name "DS4433" (20% solid content aqueous solution) manufactured by Seikoh PMC Co., Ltd., were diluted with deionized water to produce aqueous solutions with a solid content of 5% by mass, and these aqueous solutions were used in the preparation of the adhesive composition.

[0284] <(E)amine compounds> In Comparative Example 13 and Examples 11, 23, and 29 below, as the (E) amine compound, the reagent name "polyethyleneimine (average molecular weight approximately 600)" manufactured by Wako Pure Chemical Industries, Ltd. was diluted with deionized water to prepare an aqueous solution with a solid content of 10% by mass, and this aqueous solution was used to prepare the adhesive composition.

[0285] (F) Polyvinyl alcohol In Comparative Example 14, Example 12, and Example 24 below, (F) polyvinyl alcohol was (F-1) acetoacetyl group-modified polyvinyl alcohol, specifically "Gosenex Z-410" (saponification degree 97.5-99.5 mol%) manufactured by Mitsubishi Chemical Corporation, and a 5% by mass aqueous solution was obtained by diluting it with deionized water using the following method.

[0286] First, 50.0 g of the acetoacetyl-modified polyvinyl alcohol (F-1) described above was gradually added to 950.0 g of deionized water while stirring at room temperature. After stirring this solution at room temperature for 10 minutes, it was heated until the internal temperature reached 85 to 90°C, and stirring was continued at that temperature for 2 hours. After confirming the dissolution of the acetoacetyl-modified polyvinyl alcohol, the aqueous solution of acetoacetyl-modified polyvinyl alcohol was cooled to room temperature. The dissolved polyvinyl alcohol aqueous solution was then filtered through a 1 μm filter, and the water evaporated during heating and stirring was replaced with deionized water to produce an aqueous solution of acetoacetyl-modified polyvinyl alcohol with a solid content of 5% by mass. This aqueous solution was used to prepare the adhesive composition.

[0287] <(G) Epoxide Compounds> In the following Example 26, as the (G) epoxide compound, a sorbitol polyglycidyl ether, "Denacol EX-614B" (epoxy equivalent: 173, liquid), manufactured by Nagase Chemtec Co., Ltd., was diluted with deionized water to prepare an aqueous solution with a solid content of 10% by mass, and this aqueous solution was used to prepare the adhesive composition.

[0288] <(H)(thermally dissociable blocked) isocyanate group-containing aqueous compound> In Examples 25, 27-29 below, the aqueous compounds having a (H)(thermally dissociable blocked) isocyanate group were (H-1)methylethyl ketoxime blocked-diphenylmethane diisocyanate compound, "DM-6400" manufactured by Meisei Chemical Industry Co., Ltd. (blocking agent thermal dissociation temperature: approximately 130°C, solid content concentration 40% by mass), and the aqueous compound having a (H-2)(thermally dissociable blocked) isocyanate group, "Elastron BN77" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., was used as is.

[0289] <<Preparation of Latex Adhesive Composition (Comparative Example 1)>> The above (A) rubber latex and water were mixed together as shown in Table 2 (wet mixture), and the amount was adjusted so that the solid content concentration was 16% by mass. After mixing, the mixture was thoroughly stirred to obtain a latex adhesive composition (Comparative Example 1).

[0290] <<Preparation of Polyvalent Metal Salt-Latex Adhesive Compositions (Comparative Examples 2-4)>> The rubber latex having the above (A) unsaturated diene and the above (B-1 to B-3) polyvalent metal salts were mixed (wet mixture) as shown in Table 2, and the amount of water was adjusted so that the solid content concentration of the adhesive composition was 16% by mass. After mixing, the mixture was thoroughly stirred to obtain polyvalent metal salt-latex adhesive compositions (Comparative Examples 2 to 4).

[0291] <<Aqueous component-latex adhesive composition having multiple phenolic hydroxyl groups in the molecule (Comparative Example 5~ 7 ) Preparation >> The above (A) rubber latex having an unsaturated diene, and the above (C-1 -1 ~C- 1-3 The aqueous component having multiple phenolic hydroxyl groups in its molecule is mixed with the latex adhesive composition (comparative example 5~) as shown in Table 2 (wet mixture), and the amount of water is adjusted so that the solid content concentration of the adhesive composition is 16% by mass. After mixing, the mixture is thoroughly stirred. 7 ) was obtained.

[0292] <<Preparation of water-soluble component-latex adhesive compositions containing amide bond structures (Comparative Examples 9-12)>> The rubber latex having the above (A) unsaturated diene and the water-soluble components containing the above (D-1 to D-4) amide bond structures were blended (wet blending) as shown in Table 2. After adjusting the amount with water so that the solid content concentration of the adhesive composition was 16% by mass, the mixture was thoroughly stirred to obtain water-soluble component-latex adhesive compositions containing amide bond structures (Comparative Examples 9 to 12).

[0293] <<Preparation of Amine Compound-Latex Adhesive Composition (Comparative Example 13)>> The rubber latex having the above (A) unsaturated diene and the above (E-1) amine compound were blended (wet blending) as shown in Table 2, and the amount was adjusted with water so that the solid content concentration of the adhesive composition was 16% by mass. After mixing, the mixture was stirred thoroughly to obtain an aqueous component-latex adhesive composition having multiple phenolic hydroxyl groups in the molecule (Comparative Example 13).

[0294] <<Preparation of Polyvinyl Alcohol-Latex Adhesive Composition (Comparative Example 14)>> The above (A) rubber latex having an unsaturated diene and the above (F-1) acetoacetyl group-modified polyvinyl alcohol were blended (wet blending) as shown in Table 2, and the amount was adjusted with water so that the solid content concentration of the adhesive composition was 16% by mass. After mixing, the mixture was thoroughly stirred to obtain an aqueous compound adhesive composition having latex-polyvinyl alcohol (Comparative Example 14).

[0295] <<An adhesive composition that is one embodiment of the present invention (Examples 1- 3、5~ Preparation of 29) >> As shown in Tables 3 to 5, the formulation (Wet formulation) consists of the following: (B) Polyvalent metal salt (Examples 1 to 5) as specified in each formulation, water for dilution, and (B) polyvalent metal salt (Examples 1 to 5) 3、5~ 29) (C) an aqueous component having multiple phenolic hydroxyl groups in the molecule (Examples 1- 3 (1) (13-29), (D) water-soluble components containing amide bond structures (Examples 5-10, 13-22, 25-28), (E) amine compounds (Examples 11, 23, 29), (F) polyvinyl alcohol (Examples 12, 24), (A) rubber latex having an unsaturated diene (Examples 1-29), (G) epoxide compounds (Example 26), and (H) aqueous compounds having (thermally dissociable blocked) isocyanate groups (Examples 25, 27-29) are blended in this order, and after mixing so that the solid content concentration of the adhesive composition becomes 16% by mass, the mixture is stirred thoroughly to form an adhesive composition which is one embodiment of the present invention (Examples 1-29). 3、5~ 29) was obtained.

[0296] <Coating of tire cords with each adhesive composition> As the organic fiber cord, a 66 nylon tire cord with a twist structure of 1400 dtex / 2, 39 twists per 10cm on the top and 39 twists per 10cm on the bottom was used.

[0297] The above tire code, Comparative Example 1~ 7、9~ 14 and Example 1~ 3、5~ Each of the 29 adhesive compositions was used to immerse the tire cord, so that the concentration of the adhesive composition impregnating the tire cord was 3.3% by mass relative to the mass of the organic fiber cord. Next, the resin was subjected to drying in the drying zone (160°C, 60 seconds), heat curing in the hot zone while applying tension (33 N / string) (235°C, 60 seconds), and heat curing in the normalize zone while releasing the tension (235°C, 60 seconds) in sequence, to obtain Comparative Example 1~ 7、9~ 14 and Example 1~ 3、5~ Tire cords coated with each of the 29 adhesive compositions were obtained.

[0298] <Fabrication of tire cord-rubber composites> Comparative Example 1~ 7、9~ 14 and Example 1~ 3、5~ Tired pieces coated with each of the 29 adhesive compositions were embedded in an unvulcanized rubber composition and co-vulcanized at 160°C for 20 minutes. The unvulcanized rubber composition used for coating included natural rubber, styrene-butadiene rubber, carbon black, and vulcanizing chemicals.

[0299] <Evaluation of the workability of adhesive compositions> The workability of the adhesive compositions of each comparative example and example was evaluated as follows.

[0300] <<Evaluation of Mechanical Stability (Coagulation Rate)>> The mechanical stability (solidification rate) of each adhesive composition was measured in accordance with the method using a Maron-type mechanical stability tester (manufactured by Kumagai Riki Kogyo Co., Ltd., Maron Stability Tester No. 2312-II) for copolymer latex compositions as specified in JIS K6392-1995.

[0301] In summary, each adhesive composition was subjected to shear strain for 10 minutes at a compression load of 10 kg and a rotation speed of 1000 r / min using the rotor of the above-mentioned Maron-type mechanical stability tester. The solidification rate (%) was then evaluated from the amount of solidified material generated using the following formula, and rounded to three decimal places. A smaller value indicates superior mechanical stability. Coagulation rate (%) = [(Dry mass of the coagulated material) / (Mass of solids in the adhesive solution used in the test)] × 100

[0302] <<Evaluation of adhesion to the drawing roll>> The above-mentioned tire cord, which is an organic fiber cord, was subjected to a continuous 2000m treatment in an immersion treatment machine that stores each adhesive composition. The amount of each adhesive composition adhering to the drawing roll was visually inspected and evaluated on the following five-point scale. Extra large: Especially large. Large: Many. Medium: Moderate. Few: A small amount. Very little: extremely small.

[0303] <Evaluation of adhesive properties of adhesive compositions> The adhesive properties of each comparative example and example adhesive composition were evaluated as follows:

[0304] <<Evaluation of adhesive strength>> The tire cord-rubber composite obtained using each adhesive composition was pulled at a speed of 300 mm / min to separate the tire cord from the composite, and the peel resistance per tire cord was determined and defined as the adhesive force (N / cord).

[0305] <<Evaluation of the adhesion state of the coating rubber>> The tire cords peeled off from the above-mentioned tire cord-rubber composite were visually inspected for the adhesion of the covering rubber, and scored according to Table 1 below.

[0306] [Table 1]

[0307] <Results of workability and adhesion evaluation of adhesive compositions> The formulations of the adhesive compositions for each comparative example and example are shown in Tables 2 to 5 below, and the results of the workability and adhesion evaluations are shown in Tables 2 to 5 below, respectively.

[0308] [Table 2]

[0309] [Table 3]

[0310] [Table 4]

[0311] [Table 5]

[0312] (A-1): Rubber latex containing an unsaturated diene, vinylpyridine-styrene-butadiene copolymer latex synthesized by the above method, solid content concentration 41% by mass (B-1): Polyvalent metal salt (copper compound), manufactured by Tokyo Chemical Industry Co., Ltd., product name "Copper(II) gluconate" (CAS Number: 527-09-3, purity 97% or higher), solid powder. (B-2): Polyvalent metal salt (copper compound), manufactured by Kanto Chemical Co., Ltd., product name "Copper(II) Acetate Monohydrate" (CAS Number: 6046-93-1, purity 99% or higher), solid powder. (B-3): Polyvalent metal salt (iron compound), manufactured by Nacalai Tesque Co., Ltd., product name "Iron(II) Chloride Tetrahydrate" (CAS Number: 13478-10-9, purity 98% or higher), solid powder.

[0313] (C-1-1): Polyphenol (lignin sulfonate), manufactured by Tokyo Chemical Industry Co., Ltd., product name "Lignin (Alkali)" (CAS Number: 8061-51-6), partially desulfonated lignin sulfonate with reduced degree of sulfonation, solid powder (C-1-2): Polyphenol (Kraft Lignin), manufactured by Sigma-Aldrich Co., LLC, trade name "Lignin, alkali" (CAS Number: 8068-05-1), Kraft Lignin, solid powder (C-1-3): Polyphenol (condensed tannin), manufactured by Kawamura Trading Co., Ltd., product name "Mimosa", plant tannin obtained from mimosa, tannin content 72±2% (test result value), solid powder.

[0314] (D-1-1): Hydrolyzed polypeptide derived from milk, manufactured by Seiwa Kasei Co., Ltd., product name "Promis HYDOROMILK", solid content concentration = 30% by mass, aqueous solution (D-1-2): Pig skin gelatin, manufactured by Fujifilm & Wako Pure Chemical Industries, Ltd., product name "High-grade gelatin MW8000±2000" (CAS Number: 9015-54-7), solid powder. (D-2-1): Nonionic polyacrylamide, manufactured by Seikoh PMC Co., Ltd., product name "DS4399" (viscosity at 25°C = approx. 6000 mPa·s, specific gravity = 1.06), solids content concentration 20%, aqueous solution (D-2-2): Amphoteric polyacrylamide, manufactured by Seikoh PMC Co., Ltd., product name "DS4433" (viscosity at 25°C = approx. 7000 mPa·s, specific gravity = 1.07), solids content concentration 20%, aqueous solution

[0315] (E-1): Amine compound (polyethyleneimine), manufactured by Wako Pure Chemical Industries, Ltd., reagent name "Polyethyleneimine, average molecular weight 600" (CAS Number: 9002-98-6, epoxy equivalent 173 g / eq.), liquid. (F-1): Polyvinyl alcohol (acetoacetyl-modified polyvinyl alcohol), manufactured by Mitsubishi Chemical Corporation, product name "Gosenex Z-410" (purity 93.5% or higher), degree of saponification 97.5-99.5 mol%, viscosity of 4% aqueous solution at 20°C = 43.5-58.5 mPa·s (catalog value), solid powder.

[0316] (G-1): Epoxide compound, sorbitol polyglycidyl ether, manufactured by Nagase ChemteX Corporation, product name "Denacol EX-614B" (CAS Number: 68412-01-1), viscosity at 20°C = approximately 5000 mPa·s (catalog value), liquid. (H-1): Aqueous compound having a (thermally dissociable blocked) isocyanate group, manufactured by Meisei Chemical Industry Co., Ltd., product name "DM-6400" (blocking agent thermal dissociation temperature: approximately 130°C, solid content concentration 40% by mass), methyl ethyl ketoxime blocked-diphenylmethane diisocyanate compound, aqueous dispersion. (H-2): Aqueous compound having a (thermally dissociable blocked) isocyanate group, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Elastron BN77" (blocking agent thermal dissociation temperature: approx. 160°C, pH 8.0, solid content concentration 31% by mass), aqueous dispersion.

[0317] Tables 3 to 5 show that in each example, an adhesive composition was obtained that exhibited good workability and good adhesion between the organic fiber and the coated rubber composition. [Industrial applicability]

[0318] According to the present invention, it is possible to provide an adhesive composition that can ensure desired adhesion without using resorcinol and does not impair workability during use, as well as organic fiber materials, rubber articles, organic fiber-rubber composites, and tires using the same. Therefore, the present invention is applicable in industrial fields that manufacture rubber articles such as tires. [Explanation of symbols]

[0319] 1: Organic fiber cord 2: Adhesive composition 3: Immersion bath (dipping tank) 4: Organic fiber cord coated with adhesive composition 5: Puncture Roll 6: Dry Zone 7: Hot Zone 8: Normalization Zone 31: Organic fiber-rubber composite 32: Adhesive layer made from adhesive composition 33: Coated rubber composition

Claims

1. (A) Rubber latex having an unsaturated diene, (B) containing polyvalent metal salts, Furthermore, see (C) to (F) below: (C) Aqueous component having multiple phenolic hydroxyl groups in the molecule, (D) Water-soluble components containing an amide bond structure, (E) Amine compounds, (F) Polyvinyl alcohol It contains one or more components selected from the group consisting of, It does not contain resorcinol. The aforementioned (B) polyvalent metal salt is copper gluconate, which is a water-soluble polyvalent metal salt. An adhesive composition for bonding rubber and organic fibers, characterized in that the aqueous component (C) having multiple phenolic hydroxyl groups in its molecule is a plant-derived component having multiple phenolic hydroxyl groups in its molecule.

2. Furthermore, see (G) to (H) below: (G) Epoxide compounds, (H) Aqueous compound having a (thermally dissociable blocked) isocyanate group The adhesive composition according to claim 1, comprising one or more components selected from the group consisting of the following.

3. The adhesive composition according to claim 1, wherein the aqueous component having a plurality of phenolic hydroxyl groups in the molecule (C) is lignin, tannin, tannic acid, flavonoid, or a derivative thereof.

4. The adhesive composition according to claim 1, wherein the (D) water-soluble component containing the amide bond structure is a water-soluble component containing a peptide structure or a water-soluble compound containing an acrylamide structure.

5. The adhesive composition according to claim 4, wherein the (D) water-soluble component containing the amide bond structure is one or more water-soluble components selected from the group consisting of proteins and polypeptides obtained by hydrolyzing proteins.

6. The adhesive composition according to claim 5, wherein the water-soluble component containing the (D) amide bond structure is one or more proteins selected from the group consisting of casein and gelatin.

7. The adhesive composition according to claim 5, wherein the water-soluble component containing the (D) amide bond structure is a polypeptide obtained by hydrolyzing a protein derived from wool, milk, beans, silk, fish scales, or skin.

8. The adhesive composition according to claim 4, wherein the water-soluble component containing the (D) amide bond structure is an aqueous compound of polyacrylamide or a modified thereof.

9. The adhesive composition according to claim 8, wherein the water-soluble component containing the (D) amide bond structure is an amphoteric polyacrylamide.

10. The adhesive composition according to claim 1, wherein the (E) amine compound is a polyfunctional amine compound having two or more primary to tertiary amino groups.

11. The adhesive composition according to claim 1, wherein the (F) polyvinyl alcohol has a degree of saponification of 80 mol% or more.

12. The adhesive composition according to claim 1, wherein the (F) polyvinyl alcohol is acetoacetyl-modified polyvinyl alcohol.

13. The adhesive composition according to claim 2, wherein the (G) epoxide compound has two or more epoxy groups in one molecule.

14. The adhesive composition according to claim 2, wherein the (G) epoxide compound is a reaction product of polyhydric alcohols and epichlorohydrin.

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

16. The adhesive composition according to claim 15, wherein the water-dispersible (thermally dissociable blocked) isocyanate compound, which is an addition product of a polyisocyanate having an (H-1) aromatic ring and a blocking agent having one or more active hydrogen groups, is a blocked form of methylenediphenyl diisocyanate.

17. The adhesive composition according to claim 2, wherein the aqueous compound having a (H) (thermally dissociable blocked) isocyanate group is an aqueous urethane compound having a (H-2) (thermally dissociable blocked) isocyanate group.

18. The aqueous urethane compound having the (H-2) (thermally dissociable blocked) isocyanate group is (α) Organic polyisocyanate compounds having 3 to 5 functional groups and a number-average molecular weight of 2,000 or less. (β) Compounds having 2 to 4 active hydrogen groups and a number-average molecular weight of 5,000 or less. (γ) 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 respective mixing ratios of (α), (β), (γ), and (δ) relative to the total amount are: (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, 35% by mass or less, and For (δ), 5% by mass or more, and 35% by mass or less. The reaction product after mixing and reacting the ingredients in such a way, and The adhesive composition according to claim 17, wherein the molecular weight of the isocyanate group (-NCO) is 42, and the proportion of (thermally dissociable blocked) isocyanate groups in the reaction product is 0.5% by mass or more and 11% by mass or less.

19. The aqueous urethane compound having the (H-2) (thermally dissociable blocked) isocyanate group is the following general formula (1): 【Chemistry 1】 [In formula (1), A is a residue from an organic polyisocyanate compound in which the active hydrogen group has been removed. X is a residue from which the active hydrogen group has been removed from a polyol compound having two to four hydroxyl groups and a number-average molecular weight of 5,000 or less. Y is a residue from which the active hydrogen group has been removed from a thermally dissociable blocking agent. Z is a residue from which the active hydrogen group has been removed from a compound having at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain. n is an integer between 2 and 4, p + m is an integer between 2 and 4 (m ≥ 0.25). The adhesive composition according to claim 17, represented by [represented by].

20. An organic fiber material comprising organic fibers and an adhesive layer covering the surface of the organic fibers, An organic fiber material characterized in that the adhesive layer comprises the adhesive composition described in claim 1.

21. The organic fiber material according to claim 20, wherein the organic fiber is an organic fiber cord formed by twisting together a plurality of filaments.

22. The organic fiber material according to claim 21, wherein the organic fiber cord is formed by applying a lower twist and a higher twist, the fiber thickness of the twisted cord is 100 dtex to 5000 dtex, and the number of twists is 10 to 50 times / 10 cm for the lower twist and 10 to 50 times / 10 cm for the upper twist.

23. The organic fiber material according to claim 21, wherein the adhesive layer is 0.5 to 6.0% by mass of the organic fiber cord in terms of dry mass.

24. The organic fiber material according to claim 20, wherein the organic fiber is made of nylon resin.

25. A rubber article characterized by being reinforced with the organic fiber material described in Claim 20.

26. An organic fiber-rubber composite comprising an organic fiber and rubber, characterized in that the organic fiber is coated with the adhesive composition described in claim 1.

27. ​​A tire characterized by using the organic fiber-rubber composite described in Claim 26.

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