Adhesive composition, and resin material, rubber product, organic fiber-rubber composite, and tire using the same

Abstract

An object is to provide an adhesive composition which can ensure desired adhesiveness without using resorcinol and does not impair processability at the time of use, and a resin material, a rubber product, an organic fiber-rubber composite, and a tire using the same. The adhesive composition contains (A) a rubber latex having an unsaturated diene and (B) polylysine. Further, a resin material, a rubber product, an organic fiber-rubber composite, and a tire using the same are provided.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive composition and a resin material, a rubber product, an organic fiber-rubber composite, and a tire using the adhesive composition. BACKGROUND

[0002] Conventionally, in order to reinforce a rubber product such as a tire, an organic fiber such as a tire cord made of a nylon fiber or a polyester fiber is adhered to a rubber composition such as a tire rubber composition to form an organic fiber-rubber composite. For such adhesion, a method of coating the organic fiber with an adhesive composition, embedding it in a rubber composition, and co-vulcanizing it with the rubber composition is generally used.

[0003] In the process of coating the organic fiber with the adhesive composition, a solvent is generally used to adjust the viscosity of the adhesive composition, but since the solvent volatilizes in the process, it is preferable to use water, which has less environmental impact, as the solvent. Furthermore, when the organic fiber is coated with the adhesive composition by impregnation, the viscosity of the adhesive composition needs to be low enough to allow coating by impregnation.

[0004] Generally, the water-based component, i.e., a component having a property of being soluble or dispersible in water, in a water-based adhesive composition must have a polar molecular structure. However, on the other hand, a high molecular material such as rubber, an organic fiber base material, etc. used as an adherend has low polarity, and when the difference between the polarity of the surface of the rubber or the organic fiber base material and the polarity of the component contained in the adhesive composition becomes large, adhesion becomes difficult. Therefore, in order to use a water-based adhesive composition as an adhesive composition for a rubber product, the component contained in the water-based adhesive composition needs to have polarity due to its water-based property, and on the other hand, the polarity of the component needs to be controlled in such a way that the polarity does not decrease the adhesion performance due to the difference between the polarity of the component and the polarity of the adherend. Therefore, a water-based adhesive composition having a function capable of satisfying these two conflicting requirements is appropriately used.

[0005] Regarding the method of coating the organic fiber with the adhesive composition, by Figure 1 An example of a method when an organic fiber cord such as a tire cord is impregnated in an adhesive composition is described.

[0006] The organic fiber cord 1 is unwound from an unwinding roll, conveyed from the roll, and dipped into the adhesive composition 2 in an impregnation bath (impregnation tank) 3 filled with the adhesive composition 2. The organic fiber cord 4 coated with the adhesive composition 2 is pulled up from the impregnation bath 3, and excess portions of the adhesive composition 2 are removed by a squeeze roll 5. The organic fiber cord 4 coated with the adhesive composition 2 is then further conveyed by a roll, dried in a drying zone 6, subjected to heat curing of the resin while applying tension elongation in a heat zone 7, subjected to heat curing of the resin while standardizing (normalizing) at a tension precisely adjusted in order to achieve the required strength and elongation physical properties in a normalizing zone 8, subjected to heat curing of the resin while standardizing (normalizing) at a tension precisely adjusted in order to achieve the required strength and elongation physical properties in the zone, cooled by air outside the zone, and then wound on a take-up roll. In this way, the organic fiber is coated with the adhesive composition.

[0007] As the adhesive composition, an RFL (resorcinol-formaldehyde-latex) adhesive composition obtained by aging a mixture of resorcinol, formaldehyde, and rubber latex, or an adhesive composition in which a specific adhesion promoter is mixed with the RFL adhesive composition (see Patent Documents 1 to 4) is conventionally used.

[0008] It is well known that an adhesive composition composed of a water-based phenol-formaldehyde resin obtained by mixing and aging a water-dispersible rubber latex component and water-soluble resorcinol and formaldehyde (Patent Document 1) has been widely used in the rubber industry throughout the world, because it was found that this composition has both a function of adhering to rubber as a adherend and a function of adhering to a substrate surface such as an organic fiber which has a relatively low polarity. In the adhesion using the RFL adhesive composition, adhesion to the adherend rubber side is performed by the rubber latex component by means of co-vulcanization, and adhesion to the adherend substrate side is performed by the phenol-formaldehyde resin component composed of a condensate of resorcinol and formaldehyde which has adhesion properties to the organic fiber substrate.

[0009] The reason why resorcinol is preferably used here is that a phenol-based condensation resin which is a resin type having high adhesion properties to an adherend can be provided, and a resin component in which a polar functional group introduced into a phenol ring to obtain water solubility is a relatively small hydroxyl group which is difficult to become a steric hindrance and has high adhesion properties to the organic fiber substrate side can be provided.

[0010] The RFL adhesive composition is obtained by mixing and aging resorcinol, formaldehyde, and a rubber latex in which rosin acid or the like is used as an emulsifier in a polymerization process in the presence of an alkaline composition. It is presumed that this results in condensation of water-soluble resorcinol and formaldehyde in an alkaline under a condensation reaction of a resol type (see Patent Document 2), and addition condensation of rosin acid on the surface of the latex and a hydroxymethyl group at the end of a resol type phenol-formaldehyde addition condensation product (see Non-Patent Document 1).

[0011] Such aging causes the latex to be crosslinked by rosin acid with a resol type resorcinol-formaldehyde condensate, to enhance adhesion, and the latex becomes an encapsulated protective colloid complexed with the water-based resin, and when the adhesive composition is processed in a device as shown in Figure 1 When the adhesive composition is processed in a device as shown in

[0012] A water-based, i.e., having a property of being soluble or dispersible in water, adhesion promoter is used as an adhesion promoter added to the RFL adhesive composition to improve adhesion to the surface of a substrate having a lower polarity, such as an organic fiber cord material, by means of the water-based adhesive composition.

[0013] As a water-dispersible adhesion promoter, a (blocked) isocyanate having a particle size of 0.01 to 0.50 μm such as methylene diphenyl diisocyanate, etc. (see Patent Literature 3), a water-dispersible particle of a non-water-soluble linear phenol aldehyde type phenol aldehyde resin such as a cresol novolak type multifunctional epoxy resin, etc. (see Patent Literature 4), etc. are used.

[0014] As an adhesion promoter containing a water-soluble group, a sodium hydroxide solution of a linear phenol aldehyde type condensate obtained by a linear phenol aldehyde acidification reaction of resorcinol and formaldehyde (see Patent Literature 5), a phenol aldehyde resin dissolved in water in the presence of an alkaline substance such as an ammonium solution of a linear phenol aldehyde type condensate of chlorophenol and formaldehyde (see Patent Literature 5), an aqueous carbamate compound including a (thermally dissociable blocked) isocyanate group and a water-soluble group (see Patent Literature 6), etc. are used in combination with the RFL adhesive composition.

[0015] However, in recent years, from the viewpoint of reducing environmental impact, there is an increasing demand for reducing the use of resorcinol used as a water-soluble component in the RFL adhesive composition.

[0016] To address this problem, various adhesive compositions using a water-solvent system of a polyphenol not containing resorcinol have been researched and proposed.

[0017] For example, an adhesive composition for organic fibers composed of a rubber latex and a lignin resin (see Patent Literature 7), a water-based adhesive composition based on a rubber latex and a polyphenol such as a flavonoid and an aromatic polyaldehyde, etc. (see Patent Literatures 8 and 9), etc. are known as adhesive compositions not containing resorcinol and formaldehyde.

[0018] Prior Art Documents

[0019] Patent Literature

[0020] [Patent Literature 1] US2128229A

[0021] [Patent Literature 2] JP 2005-263887 A

[0022] [Patent Literature 3] JP 2006-37251 A

[0023] [Patent Literature 4] JP H09-12997 A

[0024] [Patent Literature 5] WO 97 / 013818

[0025] [Patent Literature 6] JP 2011-241402 A

[0026] [Patent Literature 7] WO 2018 / 003572

[0027] [Patent Literature 8] WO 2013 / 017421

[0028] [Patent Literature 9] JP 2016-528337 A

[0029] Non-patent Literature

[0030] [Non-patent Literature 1] Hirokazu Hakata, Network Polymer Vol. 31, No. 5, p. 252 (2010) SUMMARY

[0031] PROBLEMS TO BE SOLVED BY THE INVENTION

[0032] However, when the adhesive composition obtained by simply mixing the rubber latex and the lignin resin described in Patent Literature 7 is used as a resorcinol-free adhesive composition, the mechanical stability of the adhesive liquid under shear strain decreases due to the high viscosity of the rubber latex. Therefore, for example, as shown in FIG. 1, during the process in which the organic fiber cord 1 is coated with the adhesive composition 2 and the cord is dried and heat-cured, the adhesion of the adhesive composition 2 to the squeeze roller 5, the rollers in the drying zone 6, and the like increases, resulting in a new problem of poor processability of the process. Figure 1

[0033] Such a resorcinol- and formaldehyde-free adhesive composition can have lower adhesive properties, since the surface coated with the adhesive is roughened due to the adhesion to the device, and in addition, the crosslinking between the latex component and the resorcinol-formaldehyde condensate is not obtained, which first results in lower adhesive properties between the organic fiber and the coated rubber composition compared to the conventional RFL adhesive composition, which is also a problem.

[0034] ​Further, as described in Patent Literature 8, when a polyphenol mixed with a rubber latex is mixed with an aromatic dialdehyde having a low solubility in water such as terephthaldehyde or 2,5-furandicarboxaldehyde to produce a water-based adhesive composition, the aromatic dialdehyde is difficult to dissolve in water during production, which is insufficient in terms of processability.

[0035] Still further, the adhesive composition not containing resorcinol as described above also has a problem of reducing cord strength of an organic fiber cord coated with the adhesive composition.

[0036] Therefore, an object of the present application is to provide an adhesive composition which can ensure a required adhesive property without using resorcinol and does not impair processability at the time of use, a resin material, a rubber product, an organic fiber-rubber composite, and a tire using the same.

[0037] Solution to the problem

[0038] In order to solve the above problem, the present inventors have conducted a series of diligent studies on the composition of an adhesive composition. As a result, the present inventors have found that by blending polylysine with a predetermined rubber latex, an adhesive composition which can ensure a required adhesive property without using resorcinol and does not impair processability at the time of use can be obtained, thereby completing the present application.

[0039] In other words, the adhesive composition of the present application is characterized by containing (A) a rubber latex having an unsaturated diene and (B) polylysine.

[0040] Here, (B) polylysine is a low molecular weight natural homopolymer composed of essential amino acid L-lysine as a monomer, linked by a peptide bond, which is reacted with a polyphenol by a covalent bond using an oxidase catalyst. (B) Polylysine is usually made into a homooligopeptide of about 25 to 30 L-lysine residues, contains a hydrophilic amino group, and is a positively charged amino acid molecule in water.

[0041] The resin material of the present application is characterized in that the surface of a resin base material is coated with an adhesive layer composed of the adhesive composition. In particular, such a material can be preferably used as a rubber-resin adhesive composition.

[0042] The rubber product of the present application is characterized in that it is reinforced by a resin material.

[0043] The organic fiber-rubber composite of the present application is an organic fiber-rubber composite of an organic fiber such as a tire cord and a rubber made of a nylon fiber, a polyester fiber, or the like, which is characterized in that the organic fiber is coated with the adhesive composition.

[0044] The tire of the present application is characterized by using an organic fiber-rubber composite, particularly an organic fiber cord-rubber composite.

[0045] Effects of the Invention

[0046] According to the present application, it is possible to provide an adhesive composition which can ensure a desired adhesive property without using resorcinol and which does not impair processability at the time of use, a resin material, a rubber product, an organic fiber-rubber composite, and a tire using the same. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a schematic view illustrating an example of a method of coating an organic fiber cord with an adhesive composition by means of an impregnation treatment.

[0048] Figure 2 is a schematic view illustrating the principle of improvement of the adhesive property by the adhesive composition according to an embodiment of the present application when a water-dispersible (thermally dissociable blocked) isocyanate compound composed of an addition product of a polyisocyanate containing an aromatic ring and a blocking agent containing one or more active hydrogen groups is used as (C-1).

[0049] Figure 3 is a schematic view illustrating the principle of improvement of the adhesive property by the adhesive composition according to an embodiment of the present application when a waterborne urethane compound having a (thermally dissociable blocked) isocyanate group is used as (C-2).

[0050] Figure 4 is a schematic cross-sectional view of an example of the organic fiber-rubber composite of the present application. DETAILED DESCRIPTION

[0051] Hereinafter, the adhesive composition, the resin material, the rubber product, the organic fiber-rubber composite, and the tire of the present application will be described in detail by embodiments. These descriptions are intended to explain the present application, and are not intended to limit the present application in any way.

[0052] When a range is indicated herein, the end values of the range are also meant to be included in the range, unless otherwise specified.

[0053] [Adhesive Composition]

[0054] The adhesive composition of the present application comprises (A) a rubber latex having an unsaturated diene and (B) polylysine.

[0055] The adhesive composition according to the present application ensures good adhesion, particularly between the organic fiber and the coated rubber composition, without using resorcinol. In the adhesive composition of the present application, the (A) rubber latex having an unsaturated diene contributes to the improvement of the adhesion. The use of the (B) polylysine suppresses the tackiness of the rubber latex, which is measured as the mechanical stability of the adhesive liquid under shear strain, and thus the adhesion of the adhesive composition to a roll or the like can be suppressed, particularly during the process of coating the organic fiber with the adhesive composition and drying and heat-curing the composition, resulting in good workability. Thus, the adhesive composition according to the present application can achieve the desired adhesion without using resorcinol and also ensure good workability at the time of use. The adhesive composition according to the present application can reduce the environmental burden because resorcinol is not required. Furthermore, the addition of the (B) polylysine to the adhesive composition has the effect of extending the usable period as an adhesive due to the antibacterial effect of the adhesive composition.

[0056] Thus, the adhesive composition of the present application can be free of resorcinol. The adhesive composition of the present application is preferably free of formaldehyde.

[0057] As described below, the adhesive composition of the present application is particularly useful when applied to an organic fiber cord.

[0058] <(A) Rubber Latex Having an Unsaturated Diene>

[0059] In the adhesive composition of the present application, examples of the (A) rubber latex having an unsaturated diene include (A-1) synthetic rubber latex having an unsaturated diene and (A-2) natural rubber latex.

[0060] The (A-1) synthetic rubber latex having an unsaturated diene in the adhesive composition of the present application refers to a synthetic rubber latex containing an unsaturated diene that is vulcanized by sulfur.

[0061] One example of the principle of action exhibited by the (A-1) synthetic rubber latex having an unsaturated diene contained in the adhesive composition in one embodiment of the present application will be described with reference to Figure 2 and Figure 3 The synthetic rubber latex having an unsaturated diene 11 is a component for adhering the adhesive layer 32 composed of the adhesive composition 2 and the coated rubber composition 33, which is the adherend. The synthetic rubber latex having an unsaturated diene 11 is compatible with the rubber polymer contained in the coated rubber composition 33 as the adherend, and in addition, the unsaturated diene moiety co-vulcanizes to form a rubber co-vulcanized bond 21. As a result, the adhesive composition of the present application containing the (A-1) synthetic rubber latex having an unsaturated diene can provide good adhesion between, for example, an organic fiber cord and a coated rubber composition.

[0062] The (A-1) synthetic rubber latex having an unsaturated diene can include, but is not limited to, a styrene-butadiene copolymer rubber latex, a vinylpyridine-styrene-butadiene copolymer rubber latex, a carboxyl-modified styrene-butadiene copolymer rubber latex, a nitrile rubber latex, and a chloroprene rubber latex. These can be used alone, or two or more of them can be used in combination.

[0063] Among the rubber latices, the vinylpyridine-styrene-butadiene copolymer rubber latex is preferred. The vinylpyridine-styrene-butadiene copolymer rubber latex is a rubber latex widely used in adhesive compositions and articles such as tires, and in the adhesive composition of the present application, this rubber latex provides good adhesion between the adhesive layer and the adherend rubber because the relative softness and flexibility also allow the adhesive layer to be deformed without cracking in relation to the organic fiber cord.

[0064] The content (solid content ratio) of the (A-1) synthetic rubber latex having an unsaturated diene in the total solid content of the adhesive composition of the present application is not particularly limited, and is preferably 25% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass or more. The content of the (A-1) synthetic rubber latex having an unsaturated diene is preferably 95% by mass or less, and more preferably 90% by mass or less. When the content of the (A-1) synthetic rubber latex having an unsaturated diene is 25% by mass or more, the compatibility between the rubber polymer in the adherend rubber composition and the rubber latex in the adhesive composition becomes more suitable, and the adhesion state of the coated rubber in the organic fiber-rubber composite is more excellent. On the other hand, when the content of the (A-1) synthetic rubber latex having an unsaturated diene is 95% by mass or less, the amount of the resin component included as the other component in the adhesive composition can be ensured at a relative level higher than a certain level, as a result, the cohesive breakdown resistance of the adhesive layer is sufficiently ensured, and cracking hardly occurs in the adhesive layer, resulting in obtaining sufficient adhesion performance.

[0065] The (A-1) synthetic rubber latex having an unsaturated diene can be obtained by, for example, dissolving an emulsifier such as potassium abietate in water, adding a mixture of monomers thereto, adding an electrolyte such as sodium phosphate and a peroxide or the like as a polymerization initiator, polymerizing, then adding a charge transfer agent to stop the polymerization after reaching a predetermined conversion rate, and then removing the remaining monomers. During the polymerization, it is also preferable to use a chain transfer agent.

[0066] As emulsifiers, anionic surfactants are used, such as alkali metal salts of fatty acids, alkali metal salts of rosin acids, sodium formaldehyde condensate naphthalene sulfonate, sulfates of higher alcohols, alkylbenzene sulfonates, or aliphatic sulfonates; or nonionic surfactants, such as one or more of alkyl ester, alkyl ether, or alkyl phenyl ether types of polyethylene glycol.

[0067] Among these emulsifiers, metal salts of abietic acid, particularly alkali metal salts of abietic acid, are preferred. These can be used alone, i.e., only one, or in combination with two or more other emulsifiers. Abietic acid is a mixture of resin acids with very similar chemical structures, mainly composed of tricyclic diterpenes obtained from pine sap, etc. These resin acids have a three-ring structure, two double bonds, and a carboxyl group. The double bond portion has a highly reactive functional group that is esterified at the hydroxymethyl end of an unsaturated carboxylic acid or a methyl phenolic resin at the carboxyl group.

[0068] The amount of this emulsifier is typically 0.1 to 8 parts by mass relative to 100 parts by mass of all monomers used in latex polymerization, preferably 1 to 5 parts by mass.

[0069] As polymerization initiators, water-soluble initiators such as potassium persulfate, sodium persulfate, or ammonium persulfate, redox initiators, or oil-soluble initiators such as benzoyl peroxide can be used. Among these, potassium persulfate is preferred.

[0070] For chain transfer agents, for example, monofunctional alkyl thiols such as n-hexylthiol, tert-dodecylthiol, n-dodecylthiol, n-octylthiol, n-tetradecylthiol, or tert-hexylthiol can be used; difunctional thiols such as 1,10-decanedithiol or ethylene glycol dimercaptoacetate; trifunctional thiols such as 1,5,10-decanedithiol and trimethylolpropane trimercaptoacetate; tetrafunctional thiols such as pentaerythritol tetramercaptoacetate; disulfides; halogen compounds such as carbon tetrachloride, carbon tetrabromide, or ethylene bromide; α-methylstyrene dimers, terpinene, α-terpinene, dipentene, allyl alcohol, etc. These can be used alone or in combination of two or more.

[0071] Preferred examples of these chain transfer agents include alkyl thiols, and more preferred examples include n-octyl thiols and tert-dodecyl thiols. Tert-dodecyl thiols are preferred.

[0072] The amount of this chain transfer agent is typically 0.01 to 5 parts by mass relative to 100 parts by mass of all monomers used in latex polymerization, preferably 0.1 to 3 parts by mass.

[0073] In addition to the components mentioned above, if necessary, general additives such as antioxidants, hindered phenols, silicone-based, higher alcohol-based or mineral oil-based defoamers, reaction stoppers or antifreeze agents can be used in latex.

[0074] <<Vinylpyridine-styrene-butadiene copolymer latex>>

[0075] Vinylpyridine-styrene-butadiene copolymer rubber latex is a terpolymer of vinylpyridine monomer, styrene monomer and conjugated diene-butadiene monomer, which may further contain other monomers that can be copolymerized with these monomers.

[0076] Vinylpyridine monomers encompass vinylpyridine and substituted vinylpyridines in which the hydrogen atom in the vinylpyridine is substituted by a substituent. Examples of such vinylpyridine monomers include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and 5-ethyl-2-vinylpyridine, with 2-vinylpyridine being preferred. These vinylpyridine monomers can be used alone or in combination of two or more.

[0077] Styrene monomers encompass styrene and substituted styrene in which the hydrogen atoms of styrene are substituted by substituents. Examples of styrene monomers include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-tert-butylstyrene, and hydroxymethylstyrene, with styrene being preferred. These styrene monomers may be used alone or in combination of two or more.

[0078] Examples of conjugated butadiene monomers include aliphatic conjugated butadiene compounds, such as 1,3-butadiene and 2-methyl-1,3-butadiene, wherein 1,3-butadiene is preferred. These conjugated butadiene monomers can be used alone or in combination of two or more.

[0079] For the synthesis of vinylpyridine-styrene-butadiene copolymer rubber latex, known methods can be used, specifically, for example, the method described by the inventors in JP H09-78045. Using these methods, the same particles of vinylpyridine-styrene-butadiene copolymer rubber latex can have various compositions and intraparticle structures, for example, copolymers with uniform or different composition ratios.

[0080] Regarding vinylpyridine-styrene-butadiene copolymer rubber latexes, examples of commercially available copolymers with a homogeneous monomer mixing ratio within the same particle include Nipol 2518 manufactured by ZEON Corporation and Pyratex manufactured by NIPPONA & L INC. Examples of commercially available copolymers with different monomer mixing ratios within the same particle include V0658 manufactured by JSR Corporation. All of these can be used as (A-1) synthetic rubber latexes containing unsaturated dienes in the adhesive compositions of the present invention.

[0081] In vinylpyridine-styrene-butadiene copolymer rubber latex, the monomer ratio of vinylpyridine:styrene:butadiene is not particularly limited. Preferably, the copolymer constituting the vinylpyridine-styrene-butadiene copolymer particles comprises a copolymer prepared 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. This is because when vinylpyridine is 5% by mass or more, the pyridine portion in the rubber component with a vulcanization-promoting effect is in an appropriate amount, the degree of crosslinking by sulfur increases, and the overall adhesive strength of the adhesive layer is further improved. Furthermore, when vinylpyridine is 20% by mass or less, the degree of crosslinking of the rubber does not become over-vulcanized, and a hard adhesive can be obtained. Also, because when the amount of styrene is 10% by mass or more, the latex particles and adhesive layer will have sufficient strength and the adhesive strength will be improved, and when this amount is 40% by mass or less, the adhesive layer and the bonded rubber will have moderate co-vulcanization while still ensuring adhesive strength. Furthermore, because more suitable crosslinking can be formed when butadiene is above 45% by mass, while crosslinking is moderate when butadiene is below 75% by mass, good durability can be ensured due to changes in volume and modulus. The composition ratio of the vinylpyridine:styrene:butadiene monomer mixture can be suitably, for example, 15:15:70.

[0082] In this invention, as (A) a rubber latex having unsaturated dienes, synthetic rubber latex having unsaturated dienes (A-1) and natural rubber latex (A-2) can be used. For example, field latex, ammonia-treated latex, centrifuged concentrated latex, deproteinized latex treated with surfactants or enzymes, or combinations thereof can be used as natural rubber latex. Among these, field latex is preferred.

[0083] (A-2) The content (solid component ratio) of natural rubber latex in the total solids content of the adhesive composition of the present invention is not particularly limited, but is preferably 25% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. (A-2) The content of natural rubber latex is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0084] <(B) Polylysine>

[0085] There are no restrictions on the production methods of polylysine, but examples of polylysine include α-polylysine (a polyamino acid produced by the linear polymerization of the essential amino acid L-lysine through chemical synthesis) and ε-polylysine produced by fermentation.

[0086] Among the ε-polylysine obtained through microbial fermentation, ε-polylysine obtained by culturing polylysine-producing bacteria, represented by *Streptomyces albulus* or *Streptomyces noursei*, in a culture medium and then isolating the bacteria from the culture medium after cultivation has a degree of polymerization of 25–35 and is preferably used in this invention. The ε-polylysine obtained through microbial fermentation can be heat-treated at a temperature above 150°C in an inert gas atmosphere or vacuum (see JP2003-171463A) to obtain polylysine with a molecular weight of 30,000 or higher as measured by SDS-PAGE.

[0087] ε-poly-L-lysine is a water-soluble polyamino acid in which the amino group at the ε-position of L-lysine is peptide-bonded to the carboxyl group in a linear manner. It is an excellent cationic polymer with good biodegradability, produced by bacterial fermentation, etc., and used as a natural preservative in food. Examples of polylysine include compounds represented by structural formula (2):

[0088]

[0089] Where n represents the degree of polymerization of lysine.

[0090] The degree of polymerization (n) of polylysine is not particularly limited, as long as ε-polylysine is soluble in water, and is, for example, an integer from 3 to 300, preferably 10 or more, more preferably 15 or more. In this invention, ε-polylysine with a degree of polymerization (n) in the range of 25 to 35 is mainly used. The weight-average molecular weight of polylysine is preferably 500 or more, more preferably 2,000 or more, preferably 40,000 or less, more preferably 20,000 or less, more preferably 10,000 or less, and particularly preferably 7,000 or less.

[0091] Polylysine is usually a homopolymer of lysine, but it may also contain other amino acids as monomers.

[0092] In the adhesive composition of the present invention, (B) polylysine has the effect of inhibiting the tackiness of rubber latex and improving processability. (Refer to...) Figure 2 and 3 An example illustrating the mechanism of action of (B) polylysine contained in the adhesive composition of the present invention.

[0093] Typically, in adhesive compositions containing resorcinol and formaldehyde, these resorcinols and formaldehyde form a methyl phenolic resin-type resorcinol-formaldehyde condensate between rubber latex particles dispersed in an aqueous solvent. On the surface of the rubber latex in the adhesive composition, the hydroxymethyl group of the methyl phenolic resin-type resorcinol-formaldehyde condensate is added and co-condensed with rosin salts, etc., used as emulsifiers. A phenolic resin coating is formed through chemical crosslinking, thereby suppressing the tackiness of the rubber latex.

[0094] On the other hand, in the adhesive composition of the present invention, polylysine 12 forms a network in water below the gelation temperature and coats the surface of a synthetic rubber latex 11 (core) having unsaturated dienes. The synthetic rubber latex 11 having unsaturated dienes has a negative charge (-) on its surface due to the emulsification of carboxylic acids such as rosin esters. The cationic groups of the amino (-NH2) groups of the polylysine 12 molecules are adsorbed onto it by electrostatic attraction to form a complex, and this coating suppresses the tackiness of the synthetic rubber latex 11 having unsaturated dienes (latex-polylysine protective film effect 20).

[0095] As a result, the adhesive composition of the present invention containing (B) polylysine inhibits the tackiness of rubber latex, and its mechanical stability as an adhesive liquid under shear strain is measured, thereby enabling the adhesive composition to coat organic fiber cords and preventing the adhesive composition from adhering to rollers, etc. during drying and heat curing, thus providing good processability.

[0096] Furthermore, the polylysine 12 of the adhesive composition 2 of the present invention, which is coated on the surface of the organic fiber cord 1, is chemically crosslinked with the carboxylic acid portion of highly reactive rosin acid, etc., through amide bonds or ester bonds by heat treatment, resulting in good adhesion between the organic fiber and the coated rubber composition.

[0097] Furthermore, as described below, when the adhesive composition of the present invention comprises (C) an aqueous compound containing (thermally dissociable-terminated) isocyanate groups, in polylysine 12, the amino (-NH2), hydroxyl (-OH), etc., present in polylysine 12 are heat-treated at high temperature after drying, forming a protein-isocyanate crosslink 22 with the activated isocyanate groups 14 present in the polyurethane resin 13 formed from the aqueous compound containing (thermally dissociable-terminated) isocyanate groups. As a result, the adhesive composition containing (B) polylysine and (C) an aqueous compound containing (thermally dissociable-terminated) isocyanate groups exhibits better adhesion between organic fibers and coated rubber compositions.

[0098] The polylysine used in this invention can be obtained in powder or aqueous solution form and is used in the adhesive composition of this invention. Polylysine is preferably used in aqueous solution form.

[0099] Polylysine is a food additive used as a food preservative and is considered a safe substance. It is a natural preservative with antibacterial properties. In particular, when the adhesive composition solution is an aqueous solution with a near-neutral pH, the inclusion of polylysine can prevent bacterial spoilage and its odor.

[0100] The content (solid component ratio) of polylysine in the total solids content of the adhesive composition is not particularly limited, but is preferably 0.05% by mass or more, and more preferably 20% by mass or less. The content of polylysine in (B) is more preferably 0.2% by mass to 15% by mass, and even more preferably 0.5% by mass to 12% by mass. When the content of polylysine in (B) is 0.05% by mass or more, a bactericidal effect is obtained. When the content of polylysine in (B) is 0.2% by mass or more, the adhesion of the adhesive composition to rollers, etc., can be further suppressed, which has the advantage of better processability. Furthermore, when the content of polylysine in (B) is 20% by mass or less, the amount of polylysine contained in the adhesive layer does not become too large, and the fracture resistance of the adhesive layer can be sufficiently ensured.

[0101] <(C), (D) and (E)>

[0102] The adhesive composition of the present invention preferably further comprises one or more compounds selected from the group consisting of (C) an aqueous compound having a (thermally dissociable-terminated) isocyanate group, (D) an epoxy compound and (E) a polyphenol.

[0103] In the adhesive composition of the present invention, (C) an aqueous compound having (thermally dissociable-terminated) isocyanate groups and (D) an epoxy compound act as crosslinking agents and contribute to, for example, improving the adhesion between organic fibers and coated rubber compositions.

[0104] On the other hand, (E) polyphenols have the function of improving the affinity between the adhesive composition and the surface of the organic fiber, which in turn improves the bonding performance between the organic fiber and the coated rubber composition.

[0105] Therefore, (C) aqueous compounds with (thermally dissociable-terminated) isocyanate groups, (D) epoxy compounds, and (E) polyphenols all contribute to improved adhesive properties, such as the adhesion between organic fibers and coated rubber compositions.

[0106] <(C) Aqueous compounds with (thermally dissociable-terminated) isocyanate groups>

[0107] (C) The (thermally ionizable) isocyanate group of an aqueous compound having a (thermally ionizable) isocyanate group refers to a thermally ionizable isocyanate group or an isocyanate group. Specifically, the (thermally ionizable) isocyanate group includes: (a) a thermally ionizable isocyanate group obtained by reacting an isocyanate group with a thermally ionizable end-capping agent for the isocyanate group; (b) an isocyanate group in which the isocyanate group has not reacted with a thermally ionizable end-capping agent for the isocyanate group; (c) an isocyanate group obtained by dissociation of a thermally ionizable isocyanate group from a thermally ionizable isocyanate group by a thermally ionizable end-capping agent; and (d) an isocyanate group.

[0108] (C) The aqueous properties of aqueous compounds with (thermally dissociable-terminated) isocyanate groups imply water solubility or water dispersibility. Water solubility does not necessarily mean complete water solubility, but it does mean partial water solubility or no phase separation of the binder composition in aqueous solution.

[0109] (C) The aqueous compound having (thermally dissociable-terminated) isocyanate groups is preferably (C-1) an aqueously dispersible (thermally dissociable-terminated) isocyanate compound (hereinafter also referred to as "(C-1) component") consisting of an addition product of a polyisocyanate having an aromatic ring and a terminator having one or more active hydrogen groups. In this case, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coated rubber composition is better.

[0110] Here, regarding the (C-1) component, an active hydrogen group is a group that, when placed under suitable conditions, contains hydrogen that becomes active hydrogen, namely atomic hydrogen (hydrogen radical) and hydride ions (hydrides). Examples of active hydrogen groups include amino and hydroxyl groups.

[0111] There are no particular limitations on thermally dissociable end-capping agents, as long as the end-capping agent compound protects the isocyanate groups from any chemical reaction, while allowing the isocyanate groups to be restored by heat treatment if necessary. Specifically, the preferred thermal dissociation temperature is such that... Figure 1 In the process shown, after bonding and drying with the adhesive treatment liquid, the cross-linking reactivity of the isocyanate groups, which was suppressed by the thermally dissociative end-capping agent, can be restored at the heat treatment temperature used for thermosetting.

[0112] Examples of capping agents include, but are not particularly limited to, alcohols, phenols, active methylene groups, oximes, lactams, and amines, and specific examples include: lactams, such as ε-caprolactam, δ-pentanolactam, or γ-butyrolactam; phenols, such as phenol, cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, dinonylphenol, thiophenol, chlorophenol, or pentanophenol; oximes, such as methyl ethyl ketone oxime, acetone oxime, benzophenone oxime, or cyclohexanone oxime; alcohols, such as methanol, ethanol, butanol, isopropanol, butyl alcohol, or cyclohexanol; dialkyl malonate esters, such as dimethyl malonate or diethyl malonate; active methylene groups, such as methyl acetoacetate, ethyl acetoacetate, or acetylacetone; thiols, such as butyl mercaptan or dodecyl mercaptan; and amides, such as acetanilide or amide acetate. Acetates; imides, such as succinimide, phthalic acid imide, or maleimide; sulfites, such as sodium bisulfite; cellosolves, such as methyl cellosolve, ethyl cellosolve, or 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, or 3-methyl-5-phenylpyrazole; amines, such as dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, dicyclohexylamine, diphenylamine, dimethylaniline, N,N-diethylhydroxylamine, N,N'-diphenylformamidinium, 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.

[0113] Among these capping agents, phenol, ε-caprolactam, and ketoxime are suitable for use, as they readily achieve stable thermosetting of the adhesive composition through thermal dissociation upon heating.

[0114] (C-1) Components specifically include aromatic polyisocyanates or aromatic aliphatic polyisocyanates. Examples of aromatic isocyanates include: phenyl diisocyanates, such as m-phenylene diisocyanate or terephthalene diisocyanate; toluene diisocyanates, such as 2,4-toluene diisocyanate or 2,6-toluene diisocyanate (TDI); diphenylmethane diisocyanates, such as 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), dialkyldiphenylmethane diisocyanate or tetraalkyldiphenylmethane diisocyanate; polymethylene polyphenyl polyisocyanate (polymeric MDI); m- or p-isocyanate phenylsulfonyl isocyanate; diisocyanate biphenyls, such as 4,4'-diisocyanate biphenyl or 3,3'-dimethyl-4,4'-diisocyanate biphenyl; and naphthalene diisocyanates, such as 1,5-naphthalene diisocyanate, etc. Examples of aromatic aliphatic polyisocyanates include: xylene diisocyanates, such as m-xylene diisocyanate, p-xylene diisocyanate (XDI), or tetramethylxylene diisocyanate; diethylphenyl diisocyanate; and α,α,α,α-tetramethylxylene diisocyanate (TMXDI). Other examples include modification of polyisocyanates with carbodiimides, polyols, or urea carbamates.

[0115] Among these polyisocyanates containing aromatic rings in their molecules, from the viewpoint of the cord-bundling property of the adhesive composition, aromatic isocyanates are preferred, more preferably toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or polymethylene polyphenyl polyisocyanate (polymeric MDI), and particularly preferably diphenylmethane diisocyanate (MDI). By using end-capped methylene diphenyl isocyanate, especially end-capped methylene diphenyl diisocyanate (diphenylmethane diisocyanate) as the (C-1) component, the adhesion between the organic fibers and the coated rubber composition is improved when the adhesive composition is used with organic fibers.

[0116] More preferably, (C) the aqueous compound having (thermally dissociable-terminated) isocyanate groups is (C-2) the aqueous urethane compound having (thermally dissociable-terminated) isocyanate groups (hereinafter also simply referred to as "(C-2) component"). Similarly, in this case, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coated rubber composition is better. For ease of explanation, details of component (C-2) are described below.

[0117] The content (solids ratio) of the aqueous compound having (thermally dissociable-terminated) isocyanate groups in the total solids content of the adhesive composition of the present invention is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The content of the aqueous compound having (thermally dissociable-terminated) isocyanate groups is preferably 75% by mass or less, more preferably 60% by mass or less, and even more preferably 45% by mass or less. This is because when the content of the aqueous compound having (thermally dissociable-terminated) isocyanate groups is 5% by mass or more, the adhesion between the organic fibers and the coated rubber composition is better. Furthermore, because when the content of the aqueous compound having (thermally dissociable-terminated) isocyanate groups is 75% by mass or less, a certain relative amount of other components such as rubber latex can be maintained in the adhesive composition, resulting in better adhesion to the bonded rubber.

[0118] Here, in a conventional adhesive composition containing resorcinol and formaldehyde, an island structure is formed, in which rubber latex particles (similar to islands) are dispersed in phenolic resin (similar to sea), wherein these resorcinols and formaldehyde are co-condensed, which provides good adhesion between the phenolic resin and the organic fibers on the surface of the coated organic fibers.

[0119] On the other hand, in a suitable embodiment of the adhesive composition of the present invention, the aqueous compound (C) having (thermally dissociable-terminated) isocyanate groups, instead of the phenolic resin copolymerized with resorcinol and formaldehyde, acts as an adhesive promoter, having the following two functional effects (a) and (b). As a result, in the adhesive composition, the aqueous compound (C) having (thermally dissociable-terminated) isocyanate groups contributes to the good adhesive properties of the organic fiber and coated rubber composition.

[0120] (a) By distributing the above-mentioned aqueous compound at a location near the interface between the organic fiber and the adhesive layer made of the adhesive composition, the functional effect of promoting the adhesion between the organic fiber and the adhesive layer is achieved.

[0121] (b) By crosslinking with the isocyanate groups of a compound having (thermally dissociable-terminated) isocyanate groups, a three-dimensional network structure is formed in the adhesive layer of the adhesive composition, thereby enhancing the functional effect of the adhesive layer.

[0122] The following describes in detail an example of the principle of the two functional effects (a) and (b) of an aqueous compound having (thermally dissociable-terminated) isocyanate groups as an adhesive promoter in one embodiment of the adhesive composition of the present invention.

[0123] Specifically, also refer to Figure 2The description refers to the case where (C) is an aqueous compound having a (thermally dissociable-terminated) isocyanate group, which is component (C-1), and also refers to... Figure 3 The case where (C) is an aqueous compound having a (thermally dissociable-terminated) isocyanate group is described as component (C-2).

[0124] <<Functional effects of (a) as an adhesion promoter>>

[0125] Polyesters, such as polyethylene terephthalate, are synthetic resin materials commonly used as organic fibers, consisting of flat, linear polymer chains. The surfaces of these polymer chains or the spaces between them contain a π-electron atmosphere derived from aromatic rings and the like contained within the polymer chains. Furthermore, polyesters contain particularly few hydroxyl groups on their surfaces compared to 6,6-nylon. Therefore, to achieve sufficient adhesive strength, to disperse the adhesive composition into the spaces between the polymer chains of the organic fibers, and to bond the adhesive layer to the surface of the polymer chains of the organic fibers via the adhesive composition, adhesive compositions for organic fibers made of polyester typically contain molecules with a planar structure of aromatic rings having lateral aromatic π electrons (the portion that easily diffuses into the organic fiber) as adhesion promoters.

[0126] As a specific example of such an adhesion promoter, the (C-1) component is typically used.

[0127] The (C-1) component is preferably a (terminated) isocyanate with a particle size of 0.01 to 0.50 μm, such as methylene diphenyl diisocyanate (see Patent Document 3).

[0128] The adhesive layer containing component (C-1) is in Figure 2 As shown in the figure. In the adhesive layer 32 composed of adhesive composition 2, component (C-1) 40 diffuses into the organic fiber cord 1 (aromatic isocyanate-organic fiber diffusion effect 41) and forms polylysine isocyanate crosslink 22 by covalent bonding with polylysine 12 in the adhesive layer, thereby dispersing the adhesive composition 2 into the gaps between the polymer chains of the organic fiber cord 1, and the adhesive layer 32 composed of adhesive composition 2 adheres to the surface of the polymer chains of the organic fiber cord 1.

[0129] As described above, the particle size of the (C-1) component is preferably 0.01 to 0.50 μm. When the particle size of the (C-1) component is less than 0.01 μm, over time, the (C-1) component tends to diffuse from the surface of the polymer chains of the organic fibers into the more aromatic π-electron-rich gaps between the polymer chains of the organic fibers in the adhesive layer, which reduces its effect as an adhesion promoter. Therefore, the particle size of the (C-1) component needs to be large enough to remain on the surface of the organic fibers. When the particle size of the (C-1) component is less than 0.50 μm, the smaller the particle size of the (C-1) component, the more difficult it is for the (C-1) component to settle in the liquid, and the less likely it is to be unevenly dispersed in the adhesive layer.

[0130] More preferably, the adhesive composition comprises (C-2) an aqueous urethane compound having (thermally dissociable-terminated) isocyanate groups, which in its molecular structure includes a hydrophobic aromatic polyisocyanate moiety that is readily diffused into the organic fiber, and a hydrophilic molecular chain moiety that is not diffused into the organic fiber.

[0131] like Figure 3 As shown, the polyurethane resin 13 formed from the (C-2) component in the adhesive layer 32 of the adhesive composition 2 comprises both a portion 15 that readily interacts with the organic fiber cord 1 and a portion 16 that is difficult to diffuse into the organic fiber cord 1.

[0132] The presence of portion 15, which readily interacts with the organic fiber cord, allows the adhesive layer 32, composed of adhesive composition 2, to adhere to the surface of the polymer chains of the organic fiber cord 1. The presence of portion 16, which is difficult to diffuse into the organic fiber cord 1, allows the polyurethane resin 13 formed from the (C-2) component to maintain a functional effect that promotes adhesion at the interface with the adhesive layer 32 (aqueous polyurethane-organic fiber interface effect 24).

[0133] As a result, the adhesive composition containing the (C-2) component provides good adhesion between the organic fibers and the coated rubber composition.

[0134] When (C) is an aqueous compound having a (thermally dissociable-terminated) isocyanate group, it is an aromatic polyisocyanate compound having anionic or nonionic water-soluble functional groups. This compound tends to disperse in water from the surface of the hydrophobic organic fiber cord 1, and therefore (C-2) component is preferred.

[0135] <<(b) Functional effects as an adhesion promoter>>

[0136] In adhesive layers containing component (C-1), such as Figure 2As shown, the activated isocyanate groups from the thermally dissociated end-capping agent (C-1) 40 form polylysine isocyanate crosslinks 22 with the adjacent molecular chains of polylysine 12, resulting in an adhesive layer comprising a three-dimensional network structure. Consequently, the adhesive composition containing the (C-1) component exhibits excellent adhesion between organic fibers and the coated rubber composition.

[0137] Because the material is made by forced emulsification and dispersion of aromatic powders, stirring is preferred. Figure 1 An impregnation bath (impregnation tank) 3 is provided to prevent the compound from settling in the liquid and causing uneven dispersion and aggregation in the adhesive layer.

[0138] The adhesive composition of the present invention more preferably contains a (C-2) component as an adhesion promoter. Since the (C-2) component contains an epoxide moiety or the like in its molecule, it can be uniformly dispersed in water through self-emulsification or the like due to swelling of water.

[0139] Furthermore, since the (C-2) component, which is uniformly dispersed in water, contains a hydrophobic organic isocyanate moiety in its molecule, for example, similar to water-soluble polyurethane used as an aggregated thickener, stable aggregated micelles are formed between the hydrophobic moieties of adjacent water-soluble polyurethanes due to the hydrophobic interactions between the uniformly dispersed water-soluble polyurethanes in the liquid, thus having a three-dimensional network structure.

[0140] Next, an adhesive composition with a three-dimensional network structure is coated onto organic fibers via hydrophobic bonding, followed by drying and heat curing. Then, as... Figure 3 As shown, activated isocyanate groups 14, thermally dissociated from the end-capping agent, form activated isocyanate crosslinks 23 through covalent bonding between adjacent groups, resulting in an adhesive layer containing a three-dimensional network structure of polyurethane resin 13 formed by the (C-2) component. Consequently, the adhesive composition containing the (C-2) component provides excellent adhesion between the organic fibers and the coated rubber composition.

[0141] <<Thermolytically dissociable capping agents, water-based carbamate compounds>>

[0142] There are no particular limitations on the thermally dissociable end-capping agent for component (C-2), as long as the end-capping agent compound can be thermally treated to dissociate the end-capping agent and restore the isocyanate group if necessary, while protecting the isocyanate group from any chemical reaction. Specific examples of thermally dissociable end-capping agents include compounds similar to those used in component (C-1), with preferred examples including: phenols, such as phenol, thiophenol, chlorophenol, cresol, resorcinol, p-sec-butylphenol, p-tert-butylphenol, p-sec-pentylphenol, p-octylphenol, or p-nonylphenol; secondary or tertiary alcohols, such as isopropanol or tert-butanol; aromatic secondary amines, such as diphenylamine or dimethylaniline; phthalimides; and lactams such as δ-pentylamine. Lactams; caprolactams such as ε-caprolactam; dialkyl malonate esters, such as diethyl malonate or dimethyl malonate; active methylene compounds, such as acetylacetone or alkyl acetoacetate esters; oximes, such as acetone oxime, methyl ethyl ketone oxime or cyclohexanone oxime; basic nitrogen compounds, such as 3-hydroxypyridine, 1,2-pyrazole, 3,5-dimethylpyrazole, 1,2,4-triazole, diisopropylamine or N,N'-diphenylformamidinium and acidic sodium sulfite.

[0143] Among these capping agents, phenol, ε-caprolactam, and ketoxime are suitable for use, as they readily achieve stable thermosetting of the adhesive composition through thermal dissociation upon heating.

[0144] The aqueous characteristic of water-based carbamate compounds means water solubility or water dispersibility. Water solubility does not necessarily mean complete water solubility, but it also means partial water solubility or no phase separation of the binder composition in aqueous solution.

[0145] Aqueous carbamate compounds are compounds that form a covalent bond between the nitrogen of an amine and the carbon of a carbonyl group, meaning compounds represented by general formula (3):

[0146]

[0147] Where R and R' represent hydrocarbon groups.

[0148] (C-2) The molecular weight of the aqueous carbamate compound having (thermally dissociable-terminated) isocyanate groups is not particularly limited, as long as the compound can remain aqueous, and the number average molecular weight is preferably 1,500 to 100,000, particularly preferably 9,000 or less.

[0149] As mentioned above, there are no particular limitations on the method for synthesizing the (C-2) component, and it can be any known method, such as the method described in JP S63-51474 A.

[0150] <<Preferred embodiments of (C-2) aqueous carbamate compounds having (thermally dissociable-terminated) isocyanate groups>>

[0151] A preferred embodiment of component (C-2) is a reaction product obtained by mixing and reacting (α) an organic polyisocyanate compound containing 3 to 5 functional groups and a number-average molecular weight of 2,000 or less, (β) a compound containing 2 to 4 active hydrogen groups and a number-average molecular weight of 5,000 or less, (γ) a thermally dissociative end-capping agent, and (δ) a compound containing at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group to a predetermined mixing ratio. The product is characterized in that the isocyanate group (-NCO) has a molecular weight of 42, and the composition ratio of the (thermally dissociative end-capped) isocyanate groups in the above reaction product is 0.5% to 11% by mass. In this case, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coated rubber composition is better. This is because such component (C-2) contains both a portion composed of (thermally dissociative end-capped) isocyanate groups and a hydrophilic portion containing hydrophilic groups, which has the advantage of increasing the self-water solubility of the urethane compound.

[0152] The mixing ratios of (α), (β), (γ) and (δ) with the total amount of (α), (β), (γ) and (δ) are 40% to 85% by mass for (α), 5% to 35% by mass for (β), 5% to 35% by mass for (γ), and 5% to 35% by mass for (δ).

[0153] (α) There are no particular limitations on organic polyisocyanate compounds containing 3 to 5 functional groups and with a number average molecular weight of less than 2,000. Aromatic polyisocyanate compounds and their oligomers are preferred, but other aliphatic, alicyclic, or heterocyclic polyisocyanate compounds and their oligomers may also be used. This is because the (C-2) component is more easily dispersed in the gaps between the polymer chains of organic fibers. The (C-2) component is the reaction product of this organic polyisocyanate compound containing 3 to 5 functional groups and with a number average molecular weight of less than 2,000.

[0154] 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 diisocyanate, and lysine diisocyanate. Specific examples of alicyclic polyisocyanate compounds include cyclobutane-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, and 1,3-(isocyanate-methyl)cyclohexane. Heterocyclic polyisocyanate compounds... Examples of specific examples include toluene diisocyanate adducts of 1,3,5-tris(2'-hydroxyethyl)isocyanuric acid, and specific examples of aromatic polyisocyanate compounds include m-phenylene diisocyanate, terephthalene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate, m-tris(4-phenylisocyanate), tris(4-isocyanate-phenyl)methane, tris(4-phenylisocyanate), 3-isopropenyl-α',α'-dimethylbenzyl isocyanate and oligomers thereof, or modifications of these polyisocyanates with carbodiimides, polyols or urea carbamates.

[0155] Aromatic polyisocyanate compounds are preferred, with particularly preferred examples including methylene diphenylphenyl polyisocyanate and polyphenylene polymethylene polyisocyanate. Specifically, polyphenylene polymethylene polyisocyanates with a number-average molecular weight of 2,000 or less are preferred, and those with a number-average molecular weight of 1,000 or less are particularly preferred. This is because the (C-2) component is more easily dispersed in the gaps between the polymer chains of organic fibers, and this (C-2) component is a reaction product of (α) organic polyisocyanate compounds containing 3 to 5 functional groups and with a number-average molecular weight of 2,000 or less.

[0156] There are no particular restrictions on (β) compounds containing 2 to 4 active hydrogen groups and having a number-average molecular weight of 5,000 or less. Specific examples include compounds selected from the following groups (i) to (vii):

[0157] (i) Polyols containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000;

[0158] (ii) Polyvalent amines containing 2 to 4 primary and / or secondary amino groups and having a number-average molecular weight of less than 5,000;

[0159] (iii) Amino alcohols containing 2 to 4 primary amino groups and / or secondary amino groups and hydroxyl groups and having a number average molecular weight of less than 5,000;

[0160] (iv) Polyester polyols containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000;

[0161] (v) Polybutadiene polyols containing 2 to 4 hydroxyl groups and having a number average molecular weight of less than 5,000, and copolymers of such polyols with other vinyl monomers;

[0162] (vi) a polychloroprene polyol containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000, and copolymers of such polychloroprene polyol with other vinyl monomers; and

[0163] (vii) C2-C4 epoxy alkyl copolymers of polyamines, polyphenols and amino alcohols, C2-C4 epoxy alkyl re-additions of polyols with more than C3, C2-C4 epoxy alkyl copolymers or C3-C4 epoxy alkyl copolymers, which are polyether polyols containing 2 to 4 hydroxyl groups and having a number average molecular weight of less than 5,000.

[0164] Here, regarding the (C-2) component, an active hydrogen group is a group that, when placed under suitable conditions, contains hydrogen that becomes active hydrogen, namely atomic hydrogen (hydrogen radical) and hydride ions (hydrides). Examples of active hydrogen groups include amino and hydroxyl groups.

[0165] Examples of compounds containing at least one active hydrogen group and at least one anionic hydrophilic group, such as those containing at least one active hydrogen group and at least one anionic, cationic or nonionic hydrophilic group, include, but are not particularly limited to, aminosulfonic acids such as taurine, N-methyltaurine, N-butyltaurine or sulfabenzoic acid and aminocarboxylic acids such as glycine or alanine.

[0166] There are no particular limitations on the method of synthesizing (C-2) components by mixing and reacting (α), (β), (γ) and (δ), and it can be any known method, such as the method described in JP S63-51474.

[0167] <<Another preferred embodiment of (C-2) an aqueous carbamate compound having (thermally dissociable-terminated) isocyanate groups>>

[0168] Another preferred embodiment of component (C-2) is a reaction product obtained by mixing and reacting (α) an organic polyisocyanate compound containing 3 to 5 functional groups and having a number average molecular weight of 2,000 or less, (β) a compound containing 2 to 4 active hydrogen groups and having a number average molecular weight of 5,000 or less, (γ) a thermally dissociable end-capping agent, (δ) a compound containing at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group, and (ε) a compound containing active hydrogen groups other than (α), (β), (γ), and (δ) to a predetermined mixing ratio, characterized in that the molecular weight of the isocyanate group (-NCO) is 42, and the composition ratio of the (thermally dissociable end-capped) isocyanate group in the above reaction product is 0.5% to 11% by mass. This is because such a (C-2) component contains both a portion composed of (thermally dissociable end-capped) isocyanate groups and a hydrophilic portion containing hydrophilic groups, which has the advantage of increasing the self-water solubility of the carbamate compound.

[0169] The mixing ratios of (α), (β), (γ), and (δ) with the total amounts of (α), (β), (γ), (δ), and (ε) are 40% to less than 85% by mass for (α), 5% to 35% by mass for (β), 5% to 35% by mass for (γ), 5% to 35% by mass for (δ), and greater than 0% to 45% by mass for (ε).

[0170] Here, (α) an organic polyisocyanate compound containing 3 to 5 functional groups and having a number average molecular weight of 2,000 or less, (β) a compound containing 2 to 4 active hydrogen groups and having a number average molecular weight of 5,000 or less, (γ) a thermally dissociable end-capping agent, and (δ) a compound containing at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group, except for the mixing ratio, as described in the above <<Preferred embodiment of (C-2) aqueous urethane compound having (thermally dissociable end-capped) isocyanate groups>>.

[0171] There are no particular limitations on the method of synthesizing (C-2) components by mixing and reacting (α), (β), (γ), (δ) and (ε), and it can be any known method, such as the method described in JP S63-51474.

[0172] <<Another preferred embodiment of (C-2) an aqueous carbamate compound having (thermally dissociable-terminated) isocyanate groups>>

[0173] Another preferred embodiment of component (C-2) is represented by general formula (1):

[0174]

[0175] [in

[0176] A represents the residue of the organic polyisocyanate compound that has had its active hydrogen group removed.

[0177] X represents the residues of polyol compounds containing 2 to 4 hydroxyl groups and with a number average molecular weight of less than 5,000, after the active hydrogen groups have been removed.

[0178] Y represents the residues of the thermally dissociable end-capping agent whose active hydrogen groups have been removed.

[0179] Z represents a compound containing at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain, wherein the active hydrogen group has been removed from the residue.

[0180] n represents an integer from 2 to 4, and

[0181] p+m represents an integer from 2 to 4 (m≥0.25). Similarly, in this case, when the adhesive composition is used with organic fibers, the adhesion between the organic fibers and the coated rubber composition is better. This is because the (C-2) component contains both a portion consisting of (thermally dissociable-terminated) isocyanate groups and a hydrophilic portion containing hydrophilic groups, which has the advantage of increasing the self-water solubility of the urethane compound.

[0182] Here, the organic polyisocyanate compound A in general formula (1) is a residue from which the active hydrogen groups of the organic polyisocyanate compound have been removed, and preferably contains an aromatic ring. This is because the (C-2) component is more easily dispersed in the gaps between the polymer chains of the organic fiber.

[0183] Although not specifically limited, specific examples include methylene diphenyl polyisocyanates and polyphenyl polymethylene polyisocyanates. Polyphenyl polymethylene polyisocyanates with a number average molecular weight of 6,000 or less are preferred, and polyphenyl polymethylene polyisocyanates with a number average molecular weight of 4,000 or less are particularly preferred.

[0184] Polyol compounds containing 2 to 4 hydroxyl groups and with a number average molecular weight of 5,000 or less, wherein X in general formula (1) has had the active hydrogen group residues removed, is not particularly limited. Specific examples include compounds selected from the group consisting of (i) to (vi):

[0185] (i) Polyols containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000;

[0186] (ii) Amino alcohols containing 2 to 4 primary amino groups and / or secondary amino groups and hydroxyl groups and having a number average molecular weight of less than 5,000;

[0187] (iii) Polyester polyols containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000;

[0188] (iv) Polybutadiene polyols containing 2 to 4 hydroxyl groups and having a number average molecular weight of less than 5,000, and copolymers of such polyols with other vinyl monomers;

[0189] (v) a polychloroprene polyol containing 2 to 4 hydroxyl groups and having a number-average molecular weight of less than 5,000, and copolymers of such polyol with other vinyl monomers; and

[0190] (vi) C2-C4 epoxy alkyl copolymers of polyamines, polyphenols and amino alcohols, C2-C4 epoxy alkyl re-additions of polyols with more than C3, C2-C4 epoxy alkyl copolymers or C3-C4 epoxy alkyl copolymers, which are polyether polyols containing 2 to 4 hydroxyl groups and having a number average molecular weight of less than 5,000.

[0191] (C-2) Components are not particularly limited, and may be, for example, commercially available products manufactured by DKS Co. Ltd., such as ELASTRON BN27, BN77, or BN11. Among these, ELASTRON BN77 is preferred.

[0192] <(D) Epoxy Compounds>

[0193] One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) polylysine, and (D) an epoxy compound.

[0194] (D) Epoxy compounds refer to three-membered cyclic ethers containing oxocyclopropane (ethylene oxide) (epoxy group) in their structural formula.

[0195] (D) The epoxy compound acts as a crosslinking agent in the adhesive composition. In other words, when the adhesive composition contains the (D) epoxy compound, crosslinking is introduced between the hydroxyl groups and the amine groups in the amino acid units of (B) polylysine, resulting in a significant improvement in the fracture resistance and high-temperature bond strength of the adhesive layer.

[0196] Preferably, the (D) epoxy compound is mixed with the (C) aqueous compound having (thermally ionizable) isocyanate groups and heated. This is because when such a (D) epoxy compound is mixed with the (C) aqueous compound having (thermally ionizable) isocyanate groups and heated, crosslinking is applied to the adhesive composition mainly composed of urethane bonds through nucleophilic reactions between the epoxy groups of the (D) epoxy compound and the amines, alcohols, thiols, phenols, carboxylic acids, and (thermally ionizable) isocyanates contained in the (C) aqueous compound having (thermally ionizable) isocyanate groups, thereby suppressing stress-induced creep and flow in high-temperature regions.

[0197] Furthermore, (D) the epoxy groups of the epoxy compound are preferably multifunctional. This is because it enhances the inhibition effect, increases the fracture resistance of the adhesive layer of the adhesive composition, and also increases the bond strength at high temperatures.

[0198] (D) The epoxy compound is preferably a compound containing two or more epoxy groups per molecule. Compounds containing four or more epoxy groups per molecule are particularly preferred. This is because the polyfunctionality of the epoxy groups leads to greater inhibition of creep and flow caused by stress in high-temperature regions of the adhesive composition, resulting in higher fracture resistance and higher bond strength of the adhesive layer at high temperatures.

[0199] Specific examples of (D) epoxy compounds include reaction products of polyols such as diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythiol polyglycidyl ether, pentaerythiol polyglycidyl ether, diglycerol polyglycidyl ether, or sorbitol polyglycidyl ether and epichlorohydrin; phenolic varnish epoxy resins, such as phenolic varnish epoxy resin or cresol varnish epoxy resin; and bisphenol A epoxy resins. Reaction products of polyols and epichlorohydrin or phenolic varnish epoxy resins are preferred. In particular, when (D) the epoxy compound is a reaction product of polyols and epichlorohydrin, the compound can be dissolved or dispersed in water by emulsification, thus making it easier to produce, which is preferred. Commercially available chemicals can be used for sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, and phenolic varnish epoxy resin.

[0200] (D) Epoxides can be dissolved or dispersed in water by emulsification. For example, (D) Epoxides can be dissolved in water as is. Alternatively, the epoxide can be dissolved in a small amount of solvent as needed, and the dissolved solution can be emulsified in water using known emulsifiers such as sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, or nonylphenol ethylene oxide adduct to obtain an emulsion.

[0201] (D) The content (solid component ratio) of the epoxy compound in the total solids content of the adhesive composition of the present invention is not particularly limited, but is preferably 0.1% by mass or more, more preferably 5% by mass or more. (D) The content (solid component ratio) of the epoxy compound is preferably 40% by mass or less, more preferably 25% by mass or less. This is because when the content is 0.1% by mass or more, the adhesive properties between the resin and the bonded rubber composition become better. Furthermore, because when the content is 40% by mass or less, a certain relative amount of other components such as rubber latex blended in the adhesive composition can be ensured to be above a certain level, resulting in better adhesive properties with the bonded rubber.

[0202] <(E) Polyphenols>

[0203] One embodiment of the adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene, (B) polylysine and (E) polyphenols.

[0204] (E) Polyphenols are preferably plant-derived compounds containing multiple phenolic hydroxyl groups in their molecules. In this case, the adhesion between the organic fibers and the coated rubber composition is also better when the adhesive composition is used with organic fibers. Specific examples of (E) polyphenols include lignin, tannins, tannic acid, flavonoids and their derivatives. Again, in this case, the adhesion between the organic fibers and the coated rubber composition is better when the adhesive composition is used with organic fibers.

[0205] Although research has been conducted for a long time on isolating polyphenols, such as lignin or tannin, as components in wood or bark, and reacting these polyphenols with formaldehyde to produce adhesives (see, for example, JP H07-53858A), little knowledge is available on the production of water-based adhesive compositions that do not contain resorcinol.

[0206] (E) Polyphenols are preferably lignin or its derivatives.

[0207] Lignin, along with polysaccharides such as cellulose, is a major component of plant cell walls. Lignin contains functional groups such as hydroxyl, methoxy, carbonyl, and carboxyl groups, and can interact with cationic polymers such as polylysine, especially because phenolic hydroxyl groups are highly reactive.

[0208] Lignin is a polymer with a phenylpropane-based structure, but its molecular structure has not been fully elucidated because it is a large biopolymer with multiple molecular structures that form a three-dimensional network structure.

[0209] Separating natural lignin without altering its chemical structure is considered extremely difficult because natural lignin, along with polysaccharides such as cellulose, forms a robust composite material within plant cell walls. Various industrial separation methods have been used to extract lignin from materials such as wood. Examples of lignin obtained after separation include lignin sulfonates, sulfate lignin, soda lignin, and steam-exploded lignin. Of these industrially processed lignins, lignin obtained on a large scale from the pulp effluent of chemical pulping in pulp manufacturing processes—namely, lignin sulfonates or sulfate lignin—is a well-known material in terms of availability and economics.

[0210] Other examples of lignin include lignin modified by hydroxymethylation, epoxidation, denitrification, acylation or hydroxylation, diethanolamine modified lignin, enzyme modified lignin, laccase modified lignin, urea modified lignin, lignin sulfonates, alcel process lignin, alkaligranit process lignin, and addition polyethylene glycol lignin.

[0211] Sulfate lignin is derived from lignin produced by a chemical pulping process called sulfate cooking (high-temperature, high-pressure reaction). This process involves feeding sawdust, such as from hardwoods, softwoods, mixed hardwoods, bamboo, kenaf, or bagasse, into a cooking liquid made of sodium hydroxide / sodium sulfide in a high-temperature, high-pressure reactor. Sulfate lignin is obtained by adding acid and / or carbon dioxide to the sulfate effluent obtained after sulfate cooking to precipitate the dissolved lignin-modified product, followed by dehydration and washing of the resulting precipitate. The dehydrated and washed precipitate can be purified by adding an organic solvent such as alcohol or acetone to dissolve the precipitate, separating insoluble impurities, and drying, or by denaturation as needed to introduce various functional groups. Sulfate lignin can be obtained and used as a commercially available product. The reagent name "Lignin, Base, Sulfate" (CAS No.: 8068-05-1) manufactured by Sigma-Aldrich Co. LLC is preferred.

[0212] Lignosulfonates are lignin sulfonic acids and their salts obtained from waste liquor leached from sulfite pulp during a chemical pulping process involving sulfite cooking. The reaction involves wood chips with cooking liquor made from sulfite and / or sulfites under high temperature and pressure. Calcium lignin sulfonate, sodium lignin sulfonate, potassium lignin sulfonate, or magnesium lignin sulfonate salts are particularly preferred. Sodium lignin sulfonate is especially preferred. These lignin sulfonates are commercially available; for example, the San X series manufactured by NIPPON PAPERINDUSTRIES CO.,LTD. can be used as lignin sulfonates or modified lignin sulfonates.

[0213] Examples of high-value-added lignin sulfonates include not only high-purity products but also partially desulfonated (low-sulfonated) lignin sulfonates, wherein the degree of sulfonation is reduced by heating the lignin sulfonate in an alkaline aqueous solution using sodium hydroxide or ammonia in the presence of an oxidizing agent such as oxygen (e.g., see JP2016-135834A, etc.). As high-purity or modified lignin sulfonates, the Pearlex series manufactured by NIPPON PAPER INDUSTRIES CO.,LTD. can be used, and as partially desulfonated lignin sulfonates, the Vanillex series manufactured by Nippon PaperIndustries,Ltd. can be used. Among these, the partially desulfonated (low-sulfonated) lignin sulfonates with reduced sulfonation degree are preferably those manufactured by Tokyo Kasei Kogyo Co. under the reagent name "Lignin (Alkali)" (CAS No.: 8061-51-6, solid powder).

[0214] Tannins are a group of polyphenolic compounds found in a wide range of plants, including woody plants, as well as fruits, leaves, and seeds such as grapes, persimmons, berries, cloves, legumes, herbs, tea leaves, and cocoa beans. Tannin molecules typically contain a large number of hydroxyl groups and often also contain carboxyl groups, and tend to form strong complexes and compounds with a variety of macromolecules.

[0215] Examples of tannins include tannic acid, proanthocyanidins, flavonoids, gallic esters, and catechins, as well as derivatives such as their salts or modifications. Flavonoids are commonly found in the leaves, trunks, and bark of plants and are generally referred to as tannins, consisting of hydrolyzed and condensed tannins. These tannins are identified by the fact that condensed tannins form an insoluble precipitate when boiled in dilute hydrochloric acid, while hydrolyzed tannins hydrolyze to produce water-soluble substances.

[0216] Both hydrolyzed and condensed tannins are water-soluble and can be extracted from plant materials such as woody parts, bark, leaves, fruits, pods, or galls using methods such as hot water extraction. For example, hydrolyzed tannins can be obtained from the woody parts of chestnuts or nuts, oak bark, tea leaves, gallnuts, or galls of drupecorns, while condensed tannins can be obtained from the woody parts of euonymus, mimosa bark, persimmons, or buckwheat seeds. Among these, the reagent name "Tanonic Acid" (CAS No.: 1401-55-4-6, solid powder), manufactured by NACALAI TESQUE, INC., is a tannic acid obtained from gallnuts, etc., and is preferred as a hydrolyzed tannin; and the trade name "Mimosa" (solid powder), manufactured by Kawamura Tsusho Co., Ltd., is a condensed tannin obtained from mimosa bark.

[0217] The content of (E) polyphenols (solid component ratio) in the total solids content of the adhesive composition of the present invention is not particularly limited, but preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The content of (E) polyphenols is preferably 75% by mass or less, more preferably 50% by mass or less, and even more preferably 35% by mass or less. This is because when the content of (E) polyphenols is 2% by mass or more, the adhesive performance between the organic fibers and the coated rubber composition is better. Furthermore, because when the content of (E) polyphenols is 75% by mass or less, a certain relative amount of other components such as rubber latex can be maintained in the adhesive composition, resulting in better adhesive performance with the bonded rubber.

[0218] <<Methods for producing adhesive compositions>>

[0219] The adhesive composition of the present invention comprises (A) a rubber latex having an unsaturated diene and (B) polylysine, and suitably further comprises one or more compounds selected from the group consisting of (C) an aqueous compound having a (thermally dissociable-terminated) isocyanate group, (D) an epoxy compound and (E) a polyphenol. In producing the adhesive composition, these (A) rubber latex having an unsaturated diene and (B) polylysine, and (C) the aqueous compound having a (thermally dissociable-terminated) isocyanate group, (D) the epoxy compound and (E) the polyphenol can be mixed in any order.

[0220] However, it should be noted that when the (D) epoxy compound is mixed with water, the epoxy groups tend to react with water and gradually lose their function as a crosslinking agent. Therefore, it is preferable to use the adhesive composition for coating organic fibers as soon as possible after mixing the (D) epoxy compound with water. Specifically, after mixing the (D) epoxy compound with water, the adhesive composition is preferably used for coating organic fibers within two days, more preferably within one day.

[0221] In the adhesive composition of the present invention, the mixing mass ratio of (A) rubber latex having unsaturated dienes and (B) polylysine [(A):(B)] (based on solids) is not particularly limited, but is preferably in the range of 100:0.1 to 100:25, and more preferably in the range of 100:0.2 to 100:20.

[0222] This is because when the mixing mass ratio is 100:0.1 or higher (ratio less than 1000), a film of polylysine microcapsules of (B) can be formed around the rubber latex containing unsaturated dienes (A) as the core, and an adhesive layer with sufficient strength can also be obtained. Furthermore, because when the mixing mass ratio is 100:25 or lower (ratio more than 4), the film of polylysine microcapsules of (B) formed around the rubber latex containing unsaturated dienes (A) as the core does not become too thick, and when the coated rubber composition and the adhesive composition, as the adherend of organic fibers, are co-vulcanized and bonded, the coated rubber composition and the rubber latex containing unsaturated dienes (A) are advantageously compatible with each other, resulting in the proper initial bonding process between the coated rubber composition and the adhesive composition.

[0223] When mixing (A) a rubber latex containing an unsaturated diene with (B) polylysine, known water-soluble materials that can enhance the film composed of (B) polylysine can be used in the usual coagulation process. For example, electrolytes consisting of gum arabic, carrageenan, CMCs, cationic organic or inorganic salts such as sodium chloride, potassium chloride, magnesium chloride, or ammonium chloride, or anionic salts such as sulfates, phosphates, carbonates, or acetates can be used. Alternatively, water-soluble liquids in which the film-forming material is less soluble than water can be used, such as alcohols like ethanol or propanol, or water-soluble polymers such as isobutylene-maleic anhydride ring-opening copolymer salts.

[0224] In the adhesive composition of the present invention, the mixing mass ratio of (A) a rubber latex having an unsaturated diene to a compound selected from the group consisting of (C) an aqueous compound having a (thermally dissociable-terminated) isocyanate group, (D) an epoxy compound, and (E) a polyphenol [(A):[(C)+(D)+(E)] (based on solid content) is not particularly limited, but is preferably in the range of 100:5 to 100:300, more preferably in the range of 100:7 to 100:150, and even more preferably in the range of 100:10 to 100:60.

[0225] This is because when the mixing mass ratio is 100:5 or higher (ratio less than 20), the proportion of rubber latex with unsaturated dienes in (A) of the adhesive composition does not become too large, thus sufficiently maintaining the fracture resistance of the adhesive layer containing the adhesive composition and preventing the deterioration of adhesive performance under deformation. Furthermore, because when the mixing mass ratio is 100:300 or lower (ratio more than 1 / 3), the proportion of rubber latex with unsaturated dienes in (A) of the adhesive composition does not become too low, and when the coated rubber composition, as the adherend of the organic fiber, is co-vulcanized and bonded with the adhesive composition, the coated rubber composition and the rubber latex (A) are advantageously compatible with each other, resulting in sufficiently high adhesive performance between the coated rubber composition and the adhesive composition.

[0226] (A) rubber latex with unsaturated dienes, (B) polylysine, (C) aqueous compounds with (thermally dissociable-terminated) isocyanate groups, (D) epoxy compounds, and (E) polyphenols are preferably aqueous. This is because water can be used as a solvent and causes less environmental pollution.

[0227] [Resin Material]

[0228] The adhesive composition as described above is coated onto the surface of a resin substrate, such as a resin substrate made of polyester resin, aramid resin or acrylic resin, and an appropriate heat treatment is applied to produce an adhesive layer made of the adhesive composition, thereby preparing a resin material treated with adhesive.

[0229] The resin material of the present invention is characterized in that the surface of the resin substrate is coated with an adhesive layer consisting of an adhesive composition. This allows the resin material to have excellent durability while ensuring environmental friendliness and processability. Particularly preferably, the resin substrate is a polyester resin, an aramid resin, or an acrylic resin; in particular, a polyester resin is preferred. The resin substrate is preferably a cord obtained by twisting multiple filaments together.

[0230] Examples of methods for coating a resin substrate surface with an adhesive composition include immersing the resin substrate in the adhesive composition, applying the adhesive composition by brush or the like, and spraying the adhesive composition; a suitable method can be selected as needed. There are no particular limitations on the method for coating a resin substrate surface with an adhesive composition, and when coating a resin substrate surface with an adhesive composition, it is preferable to dissolve the adhesive composition in various solvents to reduce viscosity, as this facilitates coating. Such solvents, primarily composed of water, are environmentally preferred.

[0231] A resin material coated with an adhesive composition is dried at a temperature of, for example, 100°C to 210°C, and then subjected to heat treatment. This heat treatment is preferably performed at a temperature higher than the glass transition temperature of the polymer in the resin substrate, and more preferably at a temperature between the polymer's melting temperature and 70°C to 10°C. This is because, below the polymer's glass transition temperature, the polymer's molecular mobility is poor, and the adhesive-promoting components of the adhesive composition and the polymer cannot interact sufficiently, thus failing to achieve sufficient bond strength between the adhesive composition and the resin substrate. This resin substrate can be pretreated by electron beam, microwave, corona discharge, plasma treatment, etc.

[0232] The resin substrate can be in any of the following forms: film, cord, rope, filament, filament fragments, cord fabric, or canvas. In particular, for reinforcing rubber products such as tires or conveyor belts, cords obtained by twisting multiple filaments together are suitable as resin substrates. As a cord, cords comprising top and bottom twists are preferred, with a twist factor of 1,300 to 2,500 for the bottom twist and 900 to 1,800 for the top twist.

[0233] When the resin substrate is a cord, it is preferable that the adhesive layer in the resin material is 0.5 to 6.0% of the dry weight of the cord. By setting the dry weight of the adhesive layer within this range, appropriate adhesive performance can be ensured.

[0234] [Rubber Products]

[0235] The adhesive composition of the present invention is suitable for reinforcing a variety of rubber articles. The rubber articles of the present invention are reinforced with the aforementioned resin materials. This allows the rubber articles to have superior durability while ensuring environmental friendliness and processability. Examples of such rubber articles of the present invention include tires, as well as conveyor belts, belt harnesses, hoses, and air springs.

[0236] [Organic fiber-rubber composite]

[0237] 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 aforementioned adhesive composition. This provides good adhesive properties without the use of resorcinol, as well as an organic fiber-rubber composite with good environmental friendliness and processability. The adhesive composition of the present invention is particularly superior in terms of adhesive properties between organic fibers, such as organic fiber cords, and the coated rubber composition.

[0238] Reference Figure 4 The organic fiber-rubber composite of the present invention is described in detail.

[0239] Figure 4This is a schematic cross-sectional view of an organic fiber cord-rubber composite, illustrating an example of the organic fiber-rubber composite of the present invention. Figure 4 In the organic fiber-rubber composite 31 shown, the outer surface of the organic fiber cord 1 in the outer diameter direction is covered with an adhesive layer 32 made of the adhesive composition 2 of the present invention. The organic fiber cord 1 is further bonded to the covered rubber composition 33 on the outer side in the outer diameter direction via the adhesive layer 32 made of the adhesive composition 2, thereby forming the organic fiber-rubber composite 31 of the present invention.

[0240] The reinforcing member of a rubber article using the adhesive composition of the present invention can be an organic fiber-rubber composite, as well as a film, short fiber, or nonwoven fabric.

[0241] <Organic fiber cord>

[0242] One example of organic fibers is organic fiber cord, which is used to supplement the strength of rubber products such as tires. When using organic fiber cord as a reinforcing member, woven organic fiber yarns are first twisted into organic fiber cords. The organic fiber cords are then embedded in rubber coated with an adhesive composition and vulcanized to prepare an organic fiber-rubber composite, which can then be used as a reinforcing member in rubber products such as tires.

[0243] The materials of organic fibers are not limited, and examples may include aliphatic polyamide fibers such as polyester, 6-nylon, 6,6-nylon, or 4,6-nylon; protein fibers such as synthetic silk fibroin fibers; aromatic polyamide fibers such as polyketide fibers, poly(terephthalamide) or poly(p-phenylene terephthalamide), acrylic fibers, carbon fibers, and fiber materials represented by cellulose fibers such as rayon or lyocell fibers. Among these, polyester, 6-nylon, and 6,6-nylon are preferred, and polyester is particularly preferred.

[0244] Polyester materials are polymers containing ester bonds in their main chain; more specifically, they are polymers in which more than 80% of the repeating units in the main chain are bonded by ester bonds. Examples of polyesters include, but are not particularly limited to, polyesters obtained by condensing diols such as ethylene glycol, propylene glycol, butanediol, methoxy polyethylene glycol, or pentaerythritol with dicarboxylic acids such as terephthalic acid, isophthalic acid, or their dimethyl forms through esterification or transesterification reactions. The most representative polyester is polyethylene terephthalate.

[0245] Organic fiber cords are preferably obtained by twisting multiple monofiber filaments together, particularly for reinforcing rubber products such as tires or conveyor belts. Organic fiber cords are preferably obtained by twisting upper-twisted monofiber filaments and lower-twisted monofiber filaments together. In this case, it is more preferable that the twist coefficient of the lower twist is 1,300 to 2,500 and / or the twist coefficient of the upper twist is 900 to 1,800.

[0246] <<Coated Rubber Compositions of Organic Fiber-Rubber Composites>>

[0247] The coated rubber composition constituting the organic fiber-rubber composite of the present invention is preferably a rubber composition in which the rubber component is blended with various blending agents commonly used in the rubber industry. Here, the rubber component is not particularly limited, and examples include natural rubber and conjugated diene synthetic rubbers, such as polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), or butyl rubber (IIR), as well as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-diene copolymer rubber (EPDM), and polysiloxane rubber. Natural rubber and conjugated diene synthetic rubbers are preferred. These rubber components can be used alone or in combination of two or more.

[0248] <<Production Methods of Organic Fiber-Rubber Composites>>

[0249] Organic fiber-rubber composites can be produced by coating organic fibers, such as organic fiber cords, with the adhesive composition of the present invention to form an adhesive layer, and then co-vulcanizing the rubber latex (A) of the adhesive composition having unsaturated dienes and the rubber component in the coated rubber composition, which is the adherend of the organic fibers, to form an adhesive.

[0250] There are no particular limitations on the method of coating organic fibers with the adhesive composition of the present invention. Examples include immersing organic fibers in the adhesive composition, applying the adhesive composition to the organic fibers by brush or the like, and spraying the adhesive composition onto the organic fibers. Appropriate methods can be selected as needed.

[0251] When coating organic fibers with an adhesive composition, it is preferable to dissolve the adhesive composition in various solvents to reduce viscosity, which is beneficial for coating. This is environmentally preferred when the solvent used to reduce the viscosity of the adhesive composition is primarily composed of water.

[0252] The thickness of the adhesive layer having the adhesive composition is not particularly limited, but is preferably 50 μm or less, more preferably 0.5 μm to 30 μm.

[0253] In particular, when the organic fiber-rubber composite of the present invention is applied to tires, the adhesion durability under tire rolling tends to decrease as the amount of adhesive composition bonded by the adhesive treatment increases. This is because, due to the high rigidity of the fiber material, the adhesive composition at the interface of the fiber materials to be bonded deforms relatively little by bearing stress caused by strain; however, the deformation caused by strain increases with increasing distance from the interface. Compared to the bonded rubber material, the adhesive composition contains a larger amount of thermosetting condensate, which is harder and more brittle, and therefore more likely to lead to greater adhesion fatigue under repeated strain. From the above, the average thickness of the adhesive composition layer is preferably 50 μm or less, more preferably 0.5 μm to 30 μm.

[0254] There is no particular limitation on the concentration of the adhesive composition impregnated in the organic fibers, and it is preferably 5.0% to 25.0% by mass, more preferably 7.5% to 20.0% by mass, relative to the solid content of the organic fibers.

[0255] Similar to resin materials, organic fibers coated with adhesive compositions can be dried, heat-treated, etc.

[0256] In this invention, the tire cord is preferably made of 66 nylon organic fiber, with a twist structure of 1,400 dtex / 2, an upper twist of 39 times / 10 cm, and a lower twist of 39 times / 10 cm. Furthermore, this invention is preferably an organic fiber-rubber composite, wherein an adhesive composition is attached to the tire cord.

[0257] Finally, the organic fibers coated with the adhesive composition are bonded by co-curing the rubber latex (A) containing unsaturated dienes in the adhesive composition with the rubber component in the coated rubber composition, which is the adherend of the organic fibers.

[0258] For the co-vulcanization of the rubber component in the coated rubber composition, organic vulcanizing agents such as sulfur, thiuram polysulfides such as tetramethylthiuram disulfide or di-pentamethylenethiuram tetrasulfide, 4,4-dithiomorpholine, p-quinone dioxime, p,p'-dibenzoquinone dioxime, or cyclic sulfurimides can be used. Sulfur is preferred. Depending on the circumstances, the rubber component in the coated rubber composition can be blended with various blending agents commonly used in the rubber industry, such as fillers like carbon black, silica, or aluminum hydroxide, vulcanization accelerators, antioxidants, or softeners.

[0259] Needless to say, the adhesive composition of the present invention is also effective for bonding in bonding methods in which a vulcanizing agent contained in a synthetic resin material such as an organic fiber and / or a coated rubber composition is transferred to the adhesive composition, and the adhesive composition is crosslinked by the migrated vulcanizing agent.

[0260] [tire]

[0261] For the tires of this invention, the organic fiber-rubber composite of this invention is used. This allows for favorable bonding properties without the use of resorcinol, resulting in tires with favorable environmental friendliness and processability.

[0262] Here, in the tire of the present invention, the organic fiber-rubber composite can be used as, for example, the tire carcass, belt, belt reinforcement layer or reinforcement layer around the belt, such as the bead wrapper (flipper).

[0263] Depending on the type of tire to be applied, the tire of the present invention can be obtained by using an uncured rubber composition and curing the composition after molding, or by molding a semi-cured rubber that has undergone a pre-curing process and then further curing the rubber. In the tire of the present invention, organic fiber cords treated with the above-described adhesive composition are used in any part of the tire, and there are no particular limitations on any other components of the tire, and any known components can be used. The tire of the present invention is preferably a pneumatic tire, and the gas filled into the pneumatic tire can be ordinary or oxygen-pressure-regulated air, as well as inert gases such as nitrogen, argon, or helium.

[0264] Besides tires, adhesive compositions, resin materials, and organic fiber-rubber composites can also be applied to any rubber products, such as conveyor belts, belts, hoses, or air springs.

[0265] Example

[0266] The present invention is described in more detail below with reference to embodiments, but the present invention is not limited in any way by the following embodiments.

[0267] <(A-1) Synthetic rubber latex with unsaturated dienes>

[0268] In Comparative Examples 1, 3-9 and Examples 1-9 below, vinylpyridine-styrene-butadiene copolymer latex was prepared as follows and used as (A-1) synthetic rubber latex having unsaturated dienes, as described in Comparative Example 1 of JP H09-78045.

[0269] In a nitrogen-purged 5-liter autoclave, 130 parts by weight of deionized water and 4.0 parts by weight of potassium rosinate as an emulsifier were prepared and dissolved. To this, a monomer mixture consisting of 15 parts by weight of vinylpyridine monomer, 15 parts by weight of styrene, 70 parts by weight of butadiene, and 0.60 parts by weight of tert-dodecyl mercaptan as a chain transfer agent was added and emulsified. The temperature was then raised to 50°C, and 0.5 parts by weight of potassium persulfate was added as a polymerization initiator to begin polymerization. After the monomer mixture reached a reaction rate of 90%, 0.1 parts by weight of hydroquinone was added to stop the polymerization. Next, under reduced pressure, unreacted monomers were removed to obtain a vinylpyridine-styrene-butadiene copolymer latex with a solids concentration of 41% by weight.

[0270] <(A-2) Natural Rubber Latex>

[0271] In Comparative Example 2 and Example 10 below, field latex with a solids concentration of 60% was used as (A-2) natural rubber latex, which was adjusted to a solids concentration of 41% with deionized water.

[0272] <(B) Polylysine>

[0273] In Examples 1-10 below, Polylysine 10 (10% solid concentration, aqueous solution) manufactured by ICHIMARU PHARCOS Co., Ltd. was used as (B) polylysine.

[0274] <(C) Aqueous compounds with (thermally dissociable-terminated) isocyanate groups>

[0275] In Comparative Example 4 and Example 4 below, DM-6400 (thermal dissociation temperature of the capping agent: about 130°C, solid concentration: 25% by mass), a product of Meisei Chemical Works, Ltd., was used as isocyanate in the capped form (C-1) as an aqueous compound having (C) an isocyanate group (thermally dissociable capped).

[0276] In Comparative Examples 3 and Examples 1-3, 10 below, the product “ELASTRON BN77(F-2955D-1)” ((C-2) an aqueous carbamate compound having (thermally dissociable-terminated) isocyanate groups, manufactured by DKS Co. Ltd., with a thermal dissociation temperature of the terminator of about 160°C, pH of 8.0, and a solid concentration of 31% by mass) was used as (C) the aqueous compound having (thermally dissociable-terminated) isocyanate groups.

[0277] <(D) Epoxy Compounds>

[0278] In Comparative Example 5 and Example 5 below, DENACOL EX-614B (molecular weight: 949, epoxy equivalent: 173, solids concentration: 100% by mass) (sorbitol polyglycidyl ether) manufactured by Nagase ChemteX Corporation was diluted with deionized water as (D) epoxy compound to an aqueous solution with a solids concentration of 10% by mass and used to prepare adhesive compositions.

[0279] <(E) Polyphenols>

[0280] In Comparative Examples 6-9 and Examples 2, 6-9 below, the following polyphenols were used as (E) polyphenols: wherein the polyphenol is a type of (E-1) sulfate lignin, wherein the polyphenol is a type of (E-2) lignin sulfonate, wherein the polyphenol is a type of (E-3) hydrolyzed tannin, and wherein the polyphenol is a type of (E-4) condensed tannin. These polyphenols were diluted with deionized water to prepare an aqueous solution with a solid concentration of 5% by mass, which was used to prepare adhesive compositions.

[0281] (E-1) Product name "Lignin, Alkali" (CAS No.: 8068-05-1), sulfate lignin, manufactured by Sigma-Aldrich Co. LLC

[0282] (E-2) Trade name "Lignin (Alkali)" (CAS No.: 8061-51-6), partially desulfonated lignin sulfonate with reduced sulfonation degree, manufactured by Tokyo Kasei Kogyo Co.

[0283] (E-3) Reagent name: "Tanonic Acid" (CAS No.: 1401-55-4-6, solid powder), tannic acid, manufactured by NACALAITESQUE, INC.

[0284] (E-4) Trade name "Mimosa" (solid powder), tannin, manufactured by Kawamura Tsusho Co., Ltd.

[0285] <<Preparation of Latex Adhesive Compositions (Comparative Examples 1 and 2)>>

[0286] The amount of rubber latex (A) and water was adjusted to achieve a solid concentration of 18% by mass, and then thoroughly stirred to obtain a latex adhesive composition. In Comparative Example 1 below, a synthetic rubber latex (A-1) having unsaturated dienes was used, and in Comparative Example 2, a natural rubber latex (A-2) was used.

[0287] <<Preparation of Latex-Waterborne Polyurethane Adhesive Compositions (Comparative Examples 3 and 4)>>

[0288] (A-1) A synthetic rubber latex having an unsaturated diene and (C-1) an aqueous compound having (thermally dissociable-terminated) isocyanate groups were blended as shown in Table 3 and mixed by adjusting the amount of water so that the solids concentration of the adhesive composition was 18% by mass. The mixture was then thoroughly stirred to obtain a latex-water-based polyurethane adhesive composition (Comparative Example 3).

[0289] (A-1) A synthetic rubber latex having an unsaturated diene and (C-2) an aqueous compound having (thermally dissociable-terminated) isocyanate groups were blended as shown in Table 3 and mixed by adjusting the amount of water so that the solids concentration of the adhesive composition was 18% by mass. The mixture was then thoroughly stirred to obtain a latex-water-based polyurethane adhesive composition (Comparative Example 4).

[0290] <<Preparation of Latex-Epoxide Adhesive Composition (Comparative Example 5)>>

[0291] (A-1) A synthetic rubber latex having an unsaturated diene and (D) an epoxy compound were blended as shown in Table 3 and mixed by adjusting the amount of water to make the solid concentration of the adhesive composition 18% by mass. The mixture was then thoroughly stirred to obtain a latex-epoxide adhesive composition (Comparative Example 5).

[0292] <<Preparation of Latex-Polyphenol Adhesive Compositions (Comparative Examples 6-9)>>

[0293] (A-1) Synthetic rubber latex containing unsaturated dienes and (E) polyphenols were blended as shown in Tables 3 and 4, and the mixture was adjusted by water to make the solid concentration of the adhesive composition 18% by mass. The mixture was then thoroughly stirred to obtain latex-polyphenol adhesive compositions (Comparative Examples 6-9).

[0294] <<Preparation of adhesive compositions according to one embodiment of the present invention (Examples 1-10)>>

[0295] As shown in Tables 4 and 5, the predetermined (A) rubber latex, (B) polylysine, (C) aqueous compounds having (thermally dissociable-terminated) isocyanate groups (Examples 1-4, 10), (D) epoxy compounds (Example 5), and (E) polyphenols (Examples 2, 6-9) were sequentially blended, the amount of water was adjusted so that the solids concentration of the adhesive composition was 18% by mass, and the mixture was thoroughly stirred to obtain an adhesive composition according to one embodiment of the present invention (Examples 1-10).

[0296] <Tire cords coated with adhesive composition>

[0297] As an organic fiber cord, tire cord made of polyethylene terephthalate is used, with a twist structure of 1,670 dtex / 2, an upper twist of 39 times / 10cm, and a lower twist of 39 times / 10cm.

[0298] Tire cords were impregnated with the adhesive compositions of Comparative Examples 1-9 and Examples 1-10, such that the concentration of the adhesive composition impregnated in the tire cords was 3.8% by mass of the organic fiber cords. Next, the tire cords coated with the adhesive compositions of Comparative Examples 1-9 and Examples 1-10 were continuously dried in a drying zone (150°C, 60s), thermocured in a hot zone while applying tension (0.8 kg / pc), and thermocured in a normalizing zone while relaxing the tension (240°C, 60s).

[0299] <<Preparation of Tire Cord-Rubber Composites>>

[0300] Tire cords coated with the adhesive compositions of Comparative Examples 1-9 and Examples 1-10 were embedded in an uncured rubber composition and co-cured at 155°C for 20 minutes. The uncured rubber composition used for coating was a rubber composition containing natural rubber, styrene-butadiene rubber, carbon black, vulcanizing chemicals, etc.

[0301] <<Antibacterial Performance Evaluation>>

[0302] The compositions shown in Table 2 (wet weight) were prepared and adjusted to pH 7.0–7.5 using a phosphate buffer solution (pH 6.0) prepared according to JIS K8001 from Tokyo Kasei Kogyo Co., Ltd. The antimicrobial properties were evaluated, and the liquid was placed at 30°C for 10 days to observe surface deterioration and odor of the adhesive compositions. The following were used as (A-2) natural rubber latex, (B) polylysine, (D) epoxy compound, and (E-4) polyphenol. The aqueous compound having (thermally dissociable-terminated) isocyanate groups (C-2) was "ELASTRON BN77 (F-2955D-1)" manufactured by DKS Co., Ltd. The results are shown in Table 2. "○" marks were assigned to those that achieved antimicrobial effects, and "×" marks were assigned to those that did not achieve antimicrobial effects.

[0303] <<Evaluation of the processability of adhesive compositions>>

[0304] The processability of the adhesive compositions in each comparative example and embodiment was evaluated as follows.

[0305] <<Mechanical Stability Evaluation (Solidation Rate)>>

[0306] The mechanical stability (curing rate) of each adhesive composition was measured according to the method specified in JIS K6392-1995 using the Maron Stability Tester No. 2312-II (manufactured by KUMAGAI RIKI KOGYO Co.,Ltd.) for copolymer latex compositions.

[0307] Typically, the rotor of a Maron mechanical stability tester is used to subject each adhesive composition to shear strain for 10 minutes under a compressive load of 10 kg and a rotational speed of 1,000 r / min. The solidification rate (%) is evaluated from the amount of solidification produced using the following formula, rounded to one decimal place. The smaller the value, the better the mechanical stability.

[0308] Solidification rate (%) = [(dry mass of the solidified product) / (mass of the liquid solids component of the adhesive in the test)] × 100

[0309] <<Evaluation of the Adhesion of the Extrusion Roller>>

[0310] Polyethylene terephthalate tire cords, used as organic fiber cords, were continuously processed for 2,000 m in an impregnation machine storing various adhesive compositions, and the amount of each adhesive composition on the extrusion rollers was visually evaluated at the following five levels:

[0311] Extra large: an exceptionally large quantity;

[0312] Large: Abundant quantity;

[0313] Medium: moderate quantity;

[0314] Small: a small amount; and

[0315] Slight: very small amount.

[0316] <<Evaluation of the Adhesive Properties of Adhesive Compositions>>

[0317] The adhesive properties of the adhesive compositions of the comparative examples and embodiments were evaluated as follows.

[0318] <<Bond Strength Evaluation>>

[0319] The tire cord-rubber composite obtained by using each adhesive composition was peeled off from the tire cord-rubber composite by pulling at a speed of 300 mm / min, and the peel resistance of each tire cord was determined, which was used as the adhesive strength (N / cord).

[0320] <<Evaluation of the Adhesion State of Coated Rubber>>

[0321] Visually observe the adhesion state of the rubber coating on the tire cords peeled from the tire cord-rubber composite and score it according to Table 1 below.

[0322] [Table 1]

[0323]

[0324] <Results of processability and adhesion evaluation of the adhesive composition>

[0325] Each formulation of the adhesive composition for each comparative example and embodiment is shown in Tables 3-5 below, and the results of processability evaluation and adhesion evaluation are shown in Tables 6 and 7 below.

[0326] [Table 2]

[0327]

[0328] [Table 3]

[0329]

[0330] *A1) Vinylpyridine latex: Vinylpyridine-styrene-butadiene copolymer latex synthesized by the above method (solids concentration 41% by mass).

[0331] *A2) Natural rubber latex: Field latex (41% solids concentration)

[0332] *B1) Polylysine: Trade name "Polylysine 10" (10% solid concentration, aqueous solution), weight average molecular weight 5,000, manufactured by ICHIMARU PHARCOS Co., Ltd.

[0333] *C1) Aqueous compound with (thermally dissociable-terminated) isocyanate groups: Trade name "DM-6400" (thermal dissociation temperature of the terminator: approximately 130°C, solid concentration 25% by mass) terminated methylene diphenyl diisocyanate, manufactured by Meisei Chemical Works, Ltd.

[0334] *C2) Aqueous compound with (thermally dissociable-terminated) isocyanate groups: Trade name "ELASTRONBN77 (F-2955D-1)" (thermal dissociation temperature of the terminator: approximately 160°C, pH 8.0, solids concentration 31% by mass). An aqueous carbamate compound with (thermally dissociable-terminated) isocyanate groups, manufactured by DKS Co., Ltd.

[0335] *D1) Epoxy compound: Trade name "DENACOL EX-614B" (molecular weight 949, epoxy equivalent 173, solids concentration 10% by mass), sorbitol polyglycidyl ether, manufactured by Nagase ChemteX Corporation.

[0336] *E1) Polyphenols: Product name "Lignin, Alkali" (CAS No. 8068-05-1), sulfate lignin, manufactured by Sigma-Aldrich Co. LLC

[0337] *E2) Polyphenols: Trade name "Lignin (Alkali)" (CAS No.: 8061-51-6), partially desulfonated lignin sulfonate with reduced sulfonation degree, manufactured by Tokyo Kasei Kogyo Co.

[0338] *E3) Polyphenols: Reagent name "Tanonic Acid" (CAS No.: 1401-55-4-6, solid powder). Tanonic acid, manufactured by NACALAI TESQUE, INC.

[0339] *E4) Polyphenols: Trade name "Mimosa" (solid powder) tannins, manufactured by Kawamura Tsusho Co., Ltd.

[0340] [Table 4]

[0341]

[0342] [Table 5]

[0343]

[0344] [Table 6]

[0345]

[0346] [Table 7]

[0347]

[0348] Table 2 shows that the addition of polylysine (B) to (A) rubber latex extended the usable time as an adhesive due to the antibacterial effect of the adhesive composition.

[0349] Tables 6 and 7 show that, in each embodiment, an adhesive composition with good processability and good adhesion between the organic fiber and the coated rubber composition was obtained.

[0350] Industrial availability

[0351] According to the present invention, adhesive compositions that ensure desired bonding performance without the use of resorcinol and do not impair processability during use can be provided, as well as resin materials, rubber articles, organic fiber-rubber composites, and tires using the adhesive compositions. Therefore, the present invention can be used in industrial applications such as the production of rubber articles like tires.

[0352] Explanation of reference numerals in the attached figures

[0353] 1: Organic fiber cord

[0354] 2: Adhesive composition

[0355] 3: Immersion bath (immersion tank)

[0356] 4: Organic fiber cords coated with an adhesive composition

[0357] 5: Extrusion Roller

[0358] 6: Drying area

[0359] 7: Hot Zone

[0360] 8: Positive Fire Zone

[0361] 11: Synthetic rubber latex containing unsaturated dienes

[0362] 12: Polylysine

[0363] 13: Polyurethane resin formed from aqueous urethane compounds having (thermally dissociable-terminated) isocyanate groups.

[0364] 14: Activate isocyanate groups

[0365] 15: Parts that easily interact with organic fiber cords

[0366] 16: Parts that are difficult to diffuse into organic fiber cords

[0367] 20: Latex-Polylysine Protective Film Effect

[0368] 21: Rubber co-vulcanization bonding

[0369] 22: Polylysine isocyanate crosslinking

[0370] 23: Activated isocyanate crosslinking

[0371] 24: Waterborne polyurethane-organic fiber interface effect

[0372] 31: Organic fiber-rubber composite

[0373] 32: Adhesive layer of adhesive composition

[0374] 33: Coated rubber composition

[0375] 40: Water-dispersible (thermally dissociable-terminated) isocyanate compounds, consisting of addition products of polyisocyanates having an aromatic ring and terminators having one or more active hydrogen groups.

[0376] 41: Aromatic isocyanate-organic fiber diffusion effect

Claims

1. An adhesive composition comprising (A) a rubber latex having an unsaturated diene, (B) polylysine and (C) an aqueous compound having thermally dissociable-terminated isocyanate groups.

2. The adhesive composition according to claim 1, further comprising at least one compound selected from the group consisting of (D) to (E): (D) Epoxy compounds; and (E) Polyphenols.

3. The adhesive composition according to claim 1, wherein the aqueous compound having a thermally dissociable-terminated isocyanate group (C) is a water-dispersible thermally dissociable-terminated isocyanate compound consisting of an addition product of a polyisocyanate having an aromatic ring and a terminator having one or more active hydrogen groups.

4. The adhesive composition according to claim 3, wherein the water-dispersible, thermally dissociable, end-capped isocyanate compound consisting of an addition product of a polyisocyanate having an aromatic ring and an end-capping agent having one or more active hydrogen groups is an end-capped methylene diphenyl diisocyanate.

5. The adhesive composition according to claim 1, wherein the aqueous compound having thermally dissociable-terminated isocyanate groups (C-2) is an aqueous carbamate compound having thermally dissociable-terminated isocyanate groups.

6. The adhesive composition according to claim 5, wherein... The (C-2) aqueous carbamate compound with thermally dissociable isocyanate-terminated groups is the product of the following mixture and reaction: (α) Organic polyisocyanate compounds containing 3 to 5 functional groups and with a number-average molecular weight of less than 2000; (β) Compounds containing 2 to 4 active hydrogen groups and with a number-average molecular weight of less than 5000. (γ) Thermally dissociable capping agents, and (δ) A compound containing at least one active hydrogen group and at least one anionic, cationic, or nonionic hydrophilic group. The mixing ratios of (α), (β), (γ), and (δ) with the total amounts of (α), (β), (γ), and (δ) are as follows: For (α), 40%–85% by mass For (β), 5%–35% by mass For (γ), 5%–35% by mass, and For (δ), 5% to 35% by mass, and The isocyanate group (-NCO) has a molecular weight of 42, and the thermally dissociable-terminated isocyanate group composition ratio in the reaction product is 0.5% to 11% by mass.

7. The adhesive composition according to claim 5, wherein... The aqueous carbamate compound with thermally dissociable isocyanate groups (C-2) is represented by general formula (1): in A represents the residue of the organic polyisocyanate compound that has had its active hydrogen group removed. X represents the residues of polyol compounds containing 2 to 4 hydroxyl groups and with a number average molecular weight of less than 5,000, after the active hydrogen groups have been removed. Y represents the residues of the thermally dissociable end-capping agent that have had their active hydrogen groups removed. Z represents a residue of a compound containing at least one active hydrogen group and at least one salt-forming group or hydrophilic polyether chain, after the active hydrogen group has been removed. n represents an integer from 2 to 4, and p+m represents an integer from 2 to 4, where m ≥ 0.

25.

8. The adhesive composition according to claim 2, wherein each molecule of the (D) epoxy compound contains two or more epoxy groups.

9. The adhesive composition according to claim 2, wherein the (D) epoxy compound is a reaction product of a polyol and epichlorohydrin.

10. The adhesive composition according to claim 2, wherein the (E) polyphenol is a plant-derived compound containing multiple phenolic hydroxyl groups in its molecule.

11. The adhesive composition according to claim 2, wherein the (E) polyphenol is lignin, tannin, tannic acid, flavonoids or derivatives thereof.

12. The adhesive composition according to claim 1, wherein it does not contain resorcinol.

13. A resin material wherein the surface of a resin substrate is coated with an adhesive layer comprising the adhesive composition according to claim 1.

14. The resin material according to claim 13, wherein the resin substrate is composed of polyester resin.

15. The resin material according to claim 13, wherein the resin substrate is a cord obtained by twisting together multiple filaments.

16. The resin material according to claim 15, wherein the cord comprises a final twist and a primary twist, the twist coefficient of the primary twist being 1300 to 2500, and the twist coefficient of the final twist being 900 to 1800.

17. The resin material according to claim 15, wherein the dry weight of the adhesive layer is 0.5 to 6.0% of the mass of the cord.

18. A rubber article reinforced with the resin material according to claim 13.

19. An organic fiber-rubber composite, which is a composite of organic fibers and rubber, wherein the organic fibers are coated with the adhesive composition according to claim 1.

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

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