JP6675137B2 - Resin composition, method for producing the same, and rubber composition containing resin composition - Google Patents

Description

  The present invention relates to an improvement in a resin composition obtained from an alkylphenol or the like.

  In rubber products such as tires, belts, hoses, and the like, which need to be reinforced with reinforcing materials such as steel cords and organic fibers, strong adhesion between the rubber and the reinforcing materials is required. In order to bond with rubber, a method of treating a reinforcing material with various adhesives and a method of compounding an adhesive together with various other compounding agents in a rubber processing step are known. Among them, a method of compounding an adhesive in a rubber processing step is widely adopted because it can firmly vulcanize and bond regardless of whether or not the reinforcing material is treated with an adhesive. As an adhesive used in such a rubber processing step, p-tert-octylphenol or p-nonylphenol is reacted with formalins to obtain a cocondensate, and a cocondensate obtained by reacting the cocondensate with resorcinol ( For example, Patent Document 1) and a co-condensate obtained by reacting p-tert-butylphenol and o-phenylphenol with formalin to obtain a co-condensate and reacting the co-condensate with resorcin (for example, Patent Document 2) It has been known.

  On the other hand, the adhesive used in the rubber processing step is required to be softened in the rubber processing step. For example, in the field of rubber for tires where a phenolic resin is often used as an adhesive, it is known that a rubber processing step is usually performed at around 170 ° C. (for example, Non-Patent Document 1). Therefore, it is essential that the softening point of the resin used as the adhesive used in the rubber processing step is sufficiently lower than the maximum temperature at the time of rubber processing and is 150 ° C. or less. Further, from the viewpoint of improving the dispersibility during use of the resin, it is said that the softening point is preferably as low as possible so that the resin does not block during storage.

JP-A-6-234824 JP 2015-52097 A

Japan Rubber Association, Vol. 73 (2000), no. 9, p488-493

  The present invention is used for a rubber product to be reinforced with a reinforcing material, and is a resin composition for an adhesive used in a rubber processing step, which sufficiently reduces a softening point of the resin composition so as not to block. Accordingly, an object of the present invention is to provide a resin composition which can be efficiently dispersed at the time of kneading with rubber and a method for producing the same.

  The present inventors have conducted intensive studies to solve the problems, and as a result, when using a process oil that is usually used for processing rubber as a softener, the compatibility with the co-condensation resin described above is poor, so that mixing Separation of the resin layer and the oil layer occurs, the effect as a softening agent cannot be sufficiently obtained, and further, the resin composition is blocked due to poor compatibility, which makes industrial production difficult. While finding that a problem may occur, the cashew nut shell liquid can be specifically used as a softener for the co-condensation resin, and furthermore, by using the same, it is possible to effectively reduce the softening point of the obtained resin composition. , The dispersibility in rubber at the time of kneading can be improved, and at the same time, blocking during storage can be avoided. Specifically, the following inventions are included.

[1]
The following general formula (1)

（Ｒは分岐を有しても良いアルキル基またはフェニル基を表す。）
で表されるフェノール類、レゾルシン及びホルムアルデヒド由来の構成単位を有する共縮合樹脂及びカシューナッツシェル液を含む樹脂組成物。

(R represents an alkyl group or a phenyl group which may have a branch.)
A resin composition comprising a co-condensation resin having a structural unit derived from a phenol, resorcin and formaldehyde represented by the formula: and a cashew nut shell liquid.

[2]
The resin composition according to [1], wherein the content of the cashew nut shell liquid in the resin composition is 5 to 40% by weight.

[3]
The phenol represented by the general formula (1) is at least one selected from the group consisting of p-tert-butylphenol, o-phenylphenol, p-tert-octylphenol and cresol [1] or [2]. Resin composition.

[4]
The resin composition according to any one of [1] to [3], wherein the phenol represented by the general formula (1) is p-tert-butylphenol and o-phenylphenol.

[5]
The method for producing a resin composition according to any one of [1] to [4], comprising the following steps (I) to (III) in this order.
(I) a step of reacting one or more phenols represented by the general formula (1) with formaldehyde in the presence of an alkali to obtain a phenolic resin.
(II) a step of reacting the phenolic resin with resorcinol to obtain a cocondensation resin having a structural unit derived from phenols, resorcinol and formaldehyde represented by the general formula (1).
(III) a step of mixing the co-condensation resin with a cashew nut shell liquid.

[6]
The method for producing a resin composition according to [5], wherein the steps (II) and (III) are performed at 150 ° C. or lower.

[7]
[1] A rubber composition containing the resin composition according to any one of [4].

  According to the present invention, it is used for a rubber product to be reinforced with a reinforcing material, and it is possible to sufficiently reduce a softening point of a resin composition for an adhesive used in a rubber processing step so as not to block. At the time of kneading, the resin composition is efficiently dispersed in the rubber, and as a result, it is possible to provide a resin composition capable of strengthening the adhesion between the rubber and the reinforcing material. In addition, the resin composition of the present invention has a softening point significantly lower than 150 ° C., so that the temperature of the kneaded material at the end of rubber kneading becomes approximately 170 ° C. in addition to the compounding at the end of rubber kneading. Is also possible in a process in which the temperature of the rubber composition is lower, so that there is a feature that the timing of compounding the resin composition at the time of preparing the rubber composition becomes more flexible.

<Co-condensation resin contained in the resin composition of the present invention>
Hereinafter, the present invention will be described in detail. The co-condensation resin contained in the resin composition of the present invention has the following formula (2) in the main chain.

（Ｒは分岐を有しても良いアルキル基またはフェニル基を表す。）
で示されるフェノール類由来の構成単位、以下式（３）

(R represents an alkyl group or a phenyl group which may have a branch.)
A structural unit derived from a phenol represented by the following formula (3)

で示されるレゾルシン由来の構成単位およびホルムアルデヒド由来の構成単位を必ず含んでいることを特徴とする。なお、これら構成単位は通常、共縮合樹脂主鎖中に含まれるが、側鎖中に含まれる場合もある。

And a structural unit derived from resorcinol and formaldehyde. These structural units are usually contained in the main chain of the co-condensed resin, but may be contained in the side chains.

  Among these structural units, as the structural unit derived from the phenol represented by the above formula (2), for example, as the substituent R in the above formula (2), an alkyl group having 1 to 12 carbon atoms which may have a branch or A phenyl group is exemplified, and a methyl group, a tert-butyl group, a tert-octyl group, and a phenyl group are preferable from the viewpoint of availability of raw materials and the like. One or more of these structural units derived from phenols may be contained.

  In addition, since the use of some alkylphenols may become industrially difficult due to the laws and regulations of each country, it is unlikely to be subject to laws and regulations, and the softening point of the co-condensation resin itself is relatively low. More preferably, a co-condensation resin having a structural unit derived from two types of phenols, p-tert-butylphenol and o-phenylphenol, is possible. When a co-condensation resin having a structural unit derived from two kinds of phenols of p-tert-butylphenol and o-phenylphenol is used, the ratio thereof is set to o per mole of the structural unit derived from p-tert-butylphenol. The content of the structural unit derived from phenylphenol is preferably from 0.5 to 6 times, more preferably from 1.5 to 6 times. When the molar amount is more than 0.5 times, the softening point of the co-condensation resin itself becomes sufficiently low, and when the molar amount is 6 times or less, the co-condensation resin can be produced at lower cost.

  For example, as a ratio of these constituent units, the constituent unit derived from resorcin is usually contained in an amount of 0.5 to 2.0 times mol per 1 mol of the total amount of the constituent units derived from phenols. By adjusting the content to 0.5 times or more, it is possible to improve the ability of the rubber and the reinforcing material to be used as compounded with the rubber at the time of kneading as an adhesive. By setting the amount, it becomes possible to produce easily industrially. The structural unit derived from formaldehyde (methylene group and / or dimethylene ether group) is usually contained in an amount of 1 to 2 moles per 1 mole of the total amount of the structural units derived from phenols. By containing a formaldehyde-derived binding group in an amount of 1 mol or more, it becomes possible to reduce the production cost of the co-condensation resin.

  The ratio of these constituent units can be determined, for example, by analyzing the resin composition obtained by the present invention using NMR. Specifically, a method is exemplified in which the resin composition is analyzed by NMR, and among the obtained analysis results, the ratio is determined from an integrated value or a chemical shift derived from each structural unit.

  The co-condensation resin contained in the resin composition of the present invention may contain a structural unit other than the structural units described above, if necessary. Examples of such structural units include structural units derived from various aldehydes, which are raw materials of a co-condensation resin generally used as an adhesive used in a rubber processing step.

  The softening point of the co-condensation resin contained in the resin composition of the present invention is usually 150 ° C or lower, preferably 80 to 150 ° C, more preferably 80 to 140 ° C, and particularly preferably 90 to 130 ° C. Is particularly preferred. By setting the softening point to 150 ° C. or less, when mixing with a cashew nut shell liquid to form a resin composition, mixing with a sufficient amount of cashew nut shell liquid becomes possible, and as a result, the softening point of the resin composition is sufficiently increased. Can be reduced. Further, by setting the softening point to 80 ° C. or higher, it becomes possible to further reduce the occurrence of blocking.

<Resin composition of the present invention>
Cashew nut shell liquid (Cashew Nut Shell Liquid, hereinafter also referred to as CNSL) used in the present invention is a natural plant liquid obtained from cashew nut shells. Cashew nut shell liquid is a mixture composed of a phenol derivative having a saturated or unsaturated hydrocarbon side chain. In particular, it mainly contains anacardic acid, cardanol, cardol (also referred to as curdle), and methyl cardol (also referred to as methyl cardol) as its components. As a method for preparing the cashew nut shell liquid, there are a heating method and a solvent extraction method. Usually, an industrial cashew nut shell liquid is subjected to heat treatment. This heat treatment decarboxylates anacardic acid and converts it to cardanol. Since cardanol, cardol, and methyl cardol are the main components, the composition ratio (weight%) of generally available industrial cashew nut shell liquid ) Are cardanol (75-85%), cardol (15-20%), methyl cardol (1-5%). In the present invention, the cashew nut shell liquid is one in which each component contained in the cashew nut shell liquid is appropriately adjusted by separating and purifying the cashew nut shell liquid, or a part thereof is polymerized without adding another component to the cashew nut shell liquid. Also included is a cashew nut shell polymer that has been aged.

  Examples of commercially available cashew nut shell liquids include cashew liquid products (CNSL, LB-7000, LB-7250, CD-5L) manufactured by Tohoku Kako Co., Ltd., and TAN HOA HOP PHAT Co. , Ltd. CNSL. These cashew nut shell liquids may be used alone or as a mixture of two or more as needed.

  The content of the cashew nut shell liquid in the resin composition of the present invention is usually from 5 to 40% by weight, preferably from 10 to 30% by weight, based on the total amount of the resin composition. By setting the content to 40% by weight or less, it becomes possible to reduce blocking of the resin composition and decrease in performance as an adhesive for rubber, and by setting the content to 5% by weight or more, a softening point is obtained. Is sufficiently exhibited.

  In addition, the resin composition of the present invention may contain a softener compatible with the co-condensation resin contained in the resin composition of the present invention, if necessary, other than the cashew nut shell liquid. Examples of such a softening agent include a coumarone resin generally used in a rubber processing step.

  The softening point of the resin composition of the present invention is, for example, 150 ° C. or lower, preferably from 80 ° C. to 140 ° C., particularly preferably from 90 ° C. to 120 ° C. When the resin composition of the present invention is kneaded into rubber at a normal kneading temperature of about 170 ° C., the softening point is preferably 150 ° C. or less, but is 100 to 100 ° C. for the purpose of suppressing the evaporation of resorcinol during kneading. When kneading at a low temperature of 130 ° C., a problem of poor dispersibility may occur unless the softening point is set to 120 ° C. or lower, which is lower than the kneading temperature. As a result, the performance of the adhesive between the rubber and the reinforcing material may be reduced. It may not be sufficiently expressed. If the temperature is lower than 80 ° C., blocking may occur during storage.

  The content of free resorcinol contained in the resin composition of the present invention is preferably 8% by weight or less. When the content is 8% by weight or less, the evaporation of resorcinol during rubber kneading can be suppressed, which is preferable in working environment.

  The total amount of the phenols represented by the general formula (1), which are unreacted monomers other than free resorcin, and the residual solvent used in the reaction, which is contained in the resin composition of the present invention, may be 5% by weight or less. It is more preferably at most 3% by weight. When the content is 5% by weight or less, odors derived from unreacted monomers and residual solvents can be reduced, and volatile organic compounds are also reduced, which is environmentally preferable.

<Production method of resin composition of the present invention>
The resin composition of the present invention is obtained by mixing a co-condensation resin having a structural unit derived from phenols, resorcin and formaldehyde represented by the general formula (1) with a cashew nut shell liquid. As the co-condensation resin, those manufactured by a known method such as Patent Document 1 (Japanese Patent Application Laid-Open No. 6-234824) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2015-52097) can be used. When the cashew nut shell liquid is used in the production process of the co-condensation resin (the reaction step of the phenol, resorcin and formaldehyde represented by the above general formula (1)) in the same manner as a normal organic solvent, the cashew nut shell liquid is Due to the influence on the reaction with phenols, resorcinol and formaldehyde represented by the general formula (1), the physical properties of the obtained resin composition change, and when added to rubber to form a rubber composition, In some cases, the rubber after the vulcanization becomes unsuitable as an adhesive between the rubber and the reinforcing material, for example, becomes soft.

  Mixing the co-condensation resin having a structural unit derived from phenols, resorcinol and formaldehyde represented by the general formula (1) with a cashew nut shell liquid is performed by mixing the co-condensation resin obtained by the above-described known method with a cashew nut shell. After the liquid is put in a container, the co-condensation resin and the cashew nut shell liquid are heated to a temperature at which the co-condensation resin and the cashew nut shell liquid are sufficiently mixed (for example, 100 ° C. to 150 ° C.) and, if necessary, stirred. This is implemented by making the state sufficiently mixed. When performing the mixing operation, the container is set to normal pressure or reduced pressure, and the unreacted monomers (phenols, resorcin, and formaldehyde represented by the above general formula (1)) contained in the co-condensation resin and the solvent used in the reaction are mixed. It may be distilled off. When the resin composition of the present invention is obtained as a solid, the resin composition is obtained by cooling and solidifying the resin composition mixed as described above.

  The resin composition of the present invention obtained as described above can be used as an adhesive between rubber and various reinforcing materials by kneading into the rubber composition. It is particularly effective for vulcanization bonding with a reinforcing material. Examples of the reinforcing material include organic fibers such as nylon, rayon, polyester, and aramid, and steel cords such as brass-plated steel cord and zinc-plated steel cord. It is particularly effective for vulcanization bonding with a brass-plated steel cord. The resin composition of the present invention can be used alone or, if necessary, by mixing two or more kinds of resin compositions, for the above-mentioned applications.

<Rubber composition containing the resin composition of the present invention>
Subsequently, the rubber composition containing the resin composition of the present invention will be described in detail.

  The rubber composition of the present invention is obtained by kneading the above-described resin composition of the present invention, a rubber component, a filler, and sulfur. It is preferable to knead a vulcanization accelerator, zinc oxide, a methylene donor compound and an organic cobalt compound together with these.

  The amount of the resin composition of the present invention is usually used in the range of 0.5 to 10 parts by weight per 100 parts by weight of the rubber component. Especially, the range of 1 to 5 parts by weight is preferable. When the amount is less than 0.5 part by weight, it does not work effectively as an adhesive between the reinforcing material and the rubber. Absent.

  The rubber component used in the present invention includes natural rubber, epoxidized natural rubber, deproteinized natural rubber and other modified natural rubbers, as well as polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene Various synthetic rubbers such as rubber (BR), acrylonitrile / butadiene copolymer rubber (NBR), isoprene / isobutylene copolymer rubber (IIR), ethylene / propylene-diene copolymer rubber (EPDM), and halogenated butyl rubber (HR) For example, highly unsaturated rubbers such as natural rubber, styrene / butadiene copolymer rubber, and polybutadiene rubber are preferably used. Particularly preferred is natural rubber. It is also effective to combine several types of rubber components, such as a combination of natural rubber and styrene / butadiene copolymer rubber, and a combination of natural rubber and polybutadiene rubber.

  Examples of the natural rubber include natural rubbers of grades such as RSS # 1, RSS # 3, TSR20 and SIR20. As the epoxidized natural rubber, one having a degree of epoxidation of 10 to 60 mol% is preferable, and examples thereof include ENR25 and ENR50 manufactured by Kumpulang Gasly. As the deproteinized natural rubber, a deproteinized natural rubber having a total nitrogen content of 0.3% by weight or less is preferable. As the modified natural rubber, a modified rubber containing a polar group obtained by previously reacting 4-vinylpyridine, N, N, -dialkylaminoethyl acrylate (for example, N, N, -diethylaminoethyl acrylate), 2-hydroxyacrylate, or the like with natural rubber. Natural rubber is preferably used.

  Examples of the SBR include emulsion polymerization SBR and solution polymerization SBR described on pages 210 to 211 of "Rubber Industry Handbook <Fourth Edition>" edited by The Rubber Association of Japan. In particular, solution-polymerized SBR is preferably used, and furthermore, solution-polymerized SBR whose molecular ends are modified using 4,4′-bis- (dialkylamino) benzophenone such as “Nippol (registered trademark) NS116” manufactured by Zeon Corporation, JSR Solution-polymerized SBR whose molecular ends have been modified using a tin halide compound such as "SL574" manufactured by the company, commercially available products of silane-modified solution-polymerized SBR such as "E10" and "E15" manufactured by Asahi Kasei Corporation, lactam compounds, amide compounds, A urea compound, an N, N-dialkylacrylamide compound, an isocyanate compound, an imide compound, a silane compound having an alkoxy group (such as a trialkoxysilane compound), an aminosilane compound, or a tin compound and an alkoxy group Silane compounds having an alkyl acrylamide compound And two or more different compounds described above, such as a silane compound having an alkoxy group, and at least one of nitrogen, tin, silicon, or a plurality of these elements at the molecular terminals obtained by modifying the molecular terminals. Is particularly preferably used.

  Examples of BR include solution-polymerized BR such as high cis BR having 90% or more of cis 1,4 bonds and low cis BR having about 35% of cis bonds, and low cis BR having a high vinyl content is preferably used. . Furthermore, tin-modified BR such as “Nipol (registered trademark) BR 1250H” manufactured by Zeon Corporation, 4,4′-bis- (dialkylamino) benzophenone, tin halide compound, lactam compound, amide compound, urea compound, N, An N-dialkylacrylamide compound, an isocyanate compound, an imide compound, a silane compound having an alkoxy group (such as a trialkoxysilane compound), an aminosilane compound, or a silane compound having a tin compound and an alkoxy group; Using two or more different compounds described above, such as an alkyl acrylamide compound and a silane compound having an alkoxy group, at the molecular terminal obtained by modifying each molecular terminal, one of nitrogen, tin, and silicon, or Solution polymerization B having plural elements But particularly preferably used. These BRs are usually used in blends with natural rubber.

  As the above rubber component, natural rubber is preferable, and the ratio of the natural rubber in the rubber component is preferably 70% by weight or more.

  Examples of the filler used in the present invention include carbon black, silica, talc, clay, aluminum hydroxide, titanium oxide and the like which are generally used in the rubber field. These fillers may be used alone or as required. Two or more kinds may be used as a mixture. As these fillers, carbon black and silica are preferably used, and carbon black is more preferably used. In particular, the ratio of carbon black in the filler is preferably 70% by weight or more.

Examples of the carbon black include those described on page 494 of “Rubber Industry Handbook <Fourth Edition” ”edited by The Rubber Association of Japan, and include HAF (High Abrasion Furnace), SAF (Super Abbreviation Furnace), and ISAF (Intermediate SAF). ), FEF (Fast Extrusion Furnace), MAF, GPF (General Purpose Furnace), SRF (Semi-Reinforcing Furnace) and the like. The rubber composition for a tire tread CTAB surface 40~250m ² / g, nitrogen adsorption specific surface area 20 to 200 m ² / g, carbon black having a particle diameter 10~50nm is preferably used, with CTAB surface 70~180m ² / g Certain carbon blacks are more preferable, and examples thereof include N110, N220, N234, N299, N326, N330, N330T, N339, N343, and N351 in the ASTM standard. Further, a surface-treated carbon black in which 0.1 to 50% by weight of silica is adhered to the surface of carbon black is also preferable. Furthermore, it is also effective to combine several kinds of fillers such as a combination of carbon black and silica.

Examples of the silica include silica having a CTAB specific surface area of 50 to 180 m ² / g and a nitrogen adsorption specific surface area of 50 to 300 m ² / g, and “AQ” and “AQ-N” manufactured by Tosoh Silica Co., Ltd., Degussa Co., Ltd. “Ultrasil (registered trademark) VN3”, “Ultrasil (registered trademark) 360”, “Ultrasil (registered trademark) 7000”, “Zeosil (registered trademark) 115GR”, “Zeosil (registered trademark) 1115MP” manufactured by Rhodia Co., Ltd. And commercially available products such as "Zeosil (registered trademark) 1205MP", "Zeosil (registered trademark) Z85MP", and "Nip Seal (registered trademark) AQ" manufactured by Nippon Silica Co., Ltd. are preferably used. When silica is usually used as the filler, bis (3-triethoxysilylpropyl) tetrasulfide (“Si-69” manufactured by Degussa) and bis (3-triethoxysilylpropyl) disulfide (“Si-69” manufactured by Degussa) are used. 75 "), bis (3-diethoxymethylsilylpropyl) tetrasulfide, bis (3-diethoxymethylsilylpropyl) disulfide, S- [3- (triethoxysilyl) propyl] ester octanethioate (General Electronic Silicones, Inc.) It is preferable to add a compound having a functional group such as an element such as silicon capable of binding to silica or an alkoxysilane or the like, such as one or more silane coupling agents selected from the group consisting of “NXT silane” manufactured by Nissan Chemical Industries, Ltd.

Examples of the aluminum hydroxide include aluminum hydroxide having a nitrogen adsorption specific surface area of 5 to 250 m ² / g and a DOP oil supply of 50 to 100 ml / 100 g.

  The amount of the filler used is preferably, for example, in the range of 10 to 120 parts by weight per 100 parts by weight of the rubber component. Particularly preferred is 30 to 70 parts by weight.

  Examples of the sulfur component used in the present invention include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. Usually, powdered sulfur is preferred, and insoluble sulfur is preferred when used for tire members having a large amount of sulfur such as tire belt members. The use amount of the sulfur component is not particularly limited, but is preferably in the range of 1 to 10 parts by weight per 100 parts by weight of the rubber component. In the case of a tire belt member or the like, the range is preferably 5 to 10 parts by weight.

  Examples of the vulcanization accelerator used in the present invention include thiazole-based accelerators described in Rubber Industry Handbook <Fourth Edition> (published by the Japan Rubber Association on January 20, 1994). Vulcanization accelerators, sulfenamide vulcanization accelerators, and guanidine vulcanization accelerators are exemplified.

Specifically, for example, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS),
N, N-dicyclohexyl-2-benzothiazolesulfenamide (DCBS), 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), diphenylguanidine (DPG). Among them, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N, N-dicyclohexyl-2-benzothiazolesulfenamide ( DCBS), or a combination of dibenzothiazyl disulfide (MBTS) and diphenylguanidine (DPG).

  The amount of the vulcanization accelerator used is preferably, for example, in the range of 0.5 to 3 parts by weight per 100 parts by weight of the rubber component. Above all, the range of 0.5 to 1.2 parts by weight is particularly preferable.

  For example, the amount of zinc oxide used is preferably in the range of 3 to 15 parts by weight per 100 parts by weight of the rubber component. Especially, the range of 5 to 10 parts by weight is particularly preferable.

  Examples of the methylene donor compound used in the present invention, such as hexamethylenetetramine, hexakis (methoxymethyl) melamine, pentakis (methoxymethyl) methylolmelamine and tetrakis (methoxymethyl) dimethylolmelamine, which are commonly used in the rubber industry Can be mentioned. Among them, hexakis (methoxymethyl) melamine alone or a mixture containing the same as a main component is preferable. These formaldehyde generators can be used alone or in combination, and the compounding amount thereof is preferably in the range of about 0.5 to 4 parts by weight, preferably 1 to 3 parts by weight based on 100 parts by weight of the rubber component. The range of the degree is more preferable.

  As the organic cobalt compound used in the present invention, for example, cobalt salts such as cobalt naphthenate and cobalt stearate, and a fatty acid cobalt / boron complex compound (for example, trade name “Manobond C (registered trademark)”: manufactured by Rhodia) And the like. The amount of the organic cobalt compound used is preferably in the range of 0.05 to 0.4 parts by weight in terms of cobalt content based on 100 parts by weight of the rubber component.

  The rubber composition of the present invention can be compounded with various compounding agents conventionally used in the rubber field and kneaded. Examples of such compounding agents include antioxidants, oils, retarders, peptizers, stearic acid, and the like.

  Examples of the above antioxidants include those described on pages 436 to 443 of "Rubber Industry Handbook <4th edition>" edited by The Rubber Association of Japan. Among them, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine (6PPD), a reaction product of aniline and acetone (TMDQ), poly (2,2,4-trimethyl-1,2-) dihydro Quinoline) ("Antioxidant FR" manufactured by Matsubara Sangyo Co., Ltd.), synthetic wax (such as paraffin wax), and vegetable wax are preferably used.

  Examples of the above oils include process oils and vegetable oils. Examples of the process oil include a paraffin-based process oil, a naphthene-based process oil, and an aromatic-based process oil.

  Examples of the above retarder include phthalic anhydride, benzoic acid, salicylic acid, N-nitrosodiphenylamine, N- (cyclohexylthio) -phthalimide (CTP), a sulfonamide derivative, diphenylurea, bis (tridecyl) pentaerythritol-diphosphite and the like. N- (cyclohexylthio) -phthalimide (CTP) is preferably used.

<Method for producing rubber composition containing resin composition of the present invention>
The rubber composition containing the resin composition of the present invention can be obtained, for example, by the following method.

(A) Step of kneading the filler and the rubber component The kneading of the filler and the rubber component can be performed using a closed kneading device such as a Banbury mixer. Such kneading usually involves heat generation, and the temperature at the end of kneading is preferably in the range of 140 ° C to 180 ° C, and more preferably in the range of 150 ° C to 170 ° C. The kneading time is about 5 to 10 minutes.

(B) Step of kneading the kneaded product obtained in the step A, the sulfur component and the vulcanization accelerator The kneading of the kneaded product obtained in the step A, the sulfur component and the vulcanization accelerator is carried out, for example, by a closed type such as a Banbury mixer. It can be performed using a kneading device or an open roll. The temperature of the kneaded material at the end of kneading is preferably from 30C to 100C, more preferably from 60C to 90C. The kneading time is usually about 5 to 10 minutes.

  Since the resin composition of the present invention has a low softening point, it can be added in the step (A) or (B), but is preferably added in the step (A).

  When using zinc oxide, antioxidants, oils, fatty acids, and peptizers, it is preferable to add them in the step (A).

When using a retarder, it is preferable to add it in the step (B).

  The rubber composition containing the resin composition of the present invention thus obtained is particularly effective for vulcanization bonding with a reinforcing material. Examples of the reinforcing material include organic fibers such as nylon, rayon, polyester, and aramid, and steel cords such as brass-plated steel cord and zinc-plated steel cord. It is particularly effective for vulcanization bonding with a brass-plated steel cord.

  By molding a rubber composition containing the resin composition of the present invention together with a reinforcing material and passing through a vulcanization step, a rubber product in which the rubber and the reinforcing material are firmly bonded can be obtained. The vulcanization step is preferably performed at 120C to 180C. The vulcanization step is performed under normal pressure or under pressure.

  Hereinafter, the present invention will be described more specifically by showing examples and comparative examples. The present invention is not limited by these examples. In addition, the content of each component described in the following Production Examples, Examples and Comparative Examples, the amount of residual solvent, the amount of free monomer, unless otherwise specified, the obtained co-condensation resin, or resin containing cashew nut shell liquid It is the weight percentage of the substance relative to the total amount in the composition.

The analysis and performance evaluation of the co-condensation resin and the resin composition were performed as follows.
[1] Measurement of average molecular weight of resin The average molecular weight of the co-condensed resin and the resin composition was calculated as the weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC).
Equipment used: HLC-8220GPC (Tosoh)
Column: TSK guard column SUPER HZ-L (Tosoh)
+ TSK-GEL SUPER HZ1000 (4.6mmφ × 150mm)
+ TSK-GEL SUPER HZ2500 (4.6mmφ × 150mm)
+ TSK-GEL SUPER HZ4000 (4.6mmφ × 150mm)
Column temperature: 40 ° C
Injection volume: 10 μL
Carrier and flow rate: tetrahydrofuran 0.35 mL / min
Sample preparation: About 0.02 g of the co-condensation resin or resin composition of the present invention is dissolved in 20 mL of tetrahydrofuran.

[2] Measurement of free monomer and residual solvent The free monomer content and the residual solvent content were quantified by gas chromatography under the following conditions.
Equipment used: Gas chromatograph GC-14B manufactured by Shimadzu Corporation
Column: glass column outer diameter 5 mm x inner diameter 3.2 mm x length 3.1 m
Filler: Filler Silicone OV-17 10% Chromosorb WHP 80/100 mesh, max. temp. 340 ° C
Column temperature: 80 ° C → 280 ° C
Evaporation chamber temperature: 250 ° C
Detector temperature: 280 ° C
Detector: FID
Carrier: N ₂ (40 ml / min)
Combustion gas: hydrogen (60 kPa), air (60 kPa)
Injection volume: 2 μL
1 g of the co-condensation resin or resin composition of the present invention and 0.05 g of anisole as a standard were dissolved in 10 mL of acetone and analyzed under the above conditions. The residual solvent and free monomer content (%) in the co-condensation resin or the resin composition were quantified by an internal standard method (GC-IS method).

[3] Measurement of softening point Measured by a method based on JIS-K2207.

<Production Example 1>
"Synthesis of co-condensation resin containing structural units derived from p-tert-butylphenol, o-phenylphenol and resorcinol"
In a four-necked separable flask equipped with a reflux condenser and a thermometer, 360.0 g (4.44 mol) of 37% pure, 60.0 g (0.40 mol) of p-tert-butylphenol, and o-phenylphenol 340 were prepared. 0.0 g (2.00 mol) were added in order. Thereafter, the internal temperature was raised to 40 ° C., and 120.0 g (0.72 mol) of a 24% aqueous sodium hydroxide solution was added thereto, followed by stirring until the heat generation stopped. After confirming that the heat generation had subsided, the internal temperature was raised to 65 ° C., and the reaction was carried out at the same temperature for 2 hours.
After completion of the reaction, 105.9 g (0.32 mol) of 30% sulfuric acid and 4.53 (0.036 mol) of oxalic acid dihydrate were added, and the mixture was stirred for 0.2 hours. After stirring, the mixture was allowed to stand, and the aqueous layer was removed.
Subsequently, 369.6 g (3.36 mol) of resorcin was added, the temperature was raised to an internal temperature of 110 ° C., and dehydration was performed under slightly reduced pressure (92 kPa) for 2 hours. During this time, the internal temperature rose from 115 ° C to 118 ° C. Subsequently, the internal temperature was raised to 125 ° C., and dehydration (92 kPa) was performed for 1 hour. Subsequently, the internal temperature was raised to 140 ° C., and dehydration (92 kPa) was performed for 1 hour. Thereafter, the internal temperature was raised to 145 to 150 ° C., and the water was distilled off by keeping the temperature for 1 hour. Thereafter, the pressure was reduced to 16 kPa while maintaining the internal temperature at 140 to 150 ° C., and water was further distilled off to obtain 817 g of a brown co-condensation resin.
Average molecular weight of cocondensation resin: 2200, softening point: 125 ° C., free p-tert-butylphenol content: 0.0%, free o-phenylphenol content: 1.7%, free resorcinol content: 7.9%.

<Example 1>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 160.0 g of the co-condensation resin obtained in Production Example 1 and an industrial cashew nut shell liquid (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (at room temperature) (Oil) 40.0 g. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 1 hour while keeping the internal temperature at 140 to 150 ° C., and the co-condensation resin and the cashew nut shell liquid were mixed so as to be uniform. Then, it was taken out on a metal vat, cooled to room temperature, and crushed in a mortar to obtain 197.8 g of a brown resin composition containing a cashew nut shell liquid.
Average molecular weight of resin composition containing cashew nut shell liquid: 2060, softening point: 93 ° C., free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.1%, free resorcinol: 6.5% , Cashew nut shell liquid content: 20%.

<Example 2>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 180.0 g (2.22 mol) of 37% pure formalin, 30.0 g (0.20 mol) of p-tert-butylphenol, and o-phenylphenol 170 were added. 0.0 g (1.00 mol) were added in order. Thereafter, the internal temperature was raised to 40 ° C., 80.0 g (0.48 mol) of a 24% aqueous sodium hydroxide solution was added, and the mixture was stirred until the heat generation stopped. After confirming that the heat generation had subsided, the internal temperature was raised to 65 ° C., and the reaction was carried out at the same temperature for 2 hours.
After completion of the reaction, 70.5 g (0.22 mol) of 30% sulfuric acid and 3.02 (0.024 mol) of oxalic acid dihydrate were added, and the mixture was stirred for 0.2 hours. Then, 25.0 g of sodium sulfate was added, and the mixture was added for 0.2 hours. After stirring, the mixture was allowed to stand, and the aqueous layer was removed.
Subsequently, 171.6 g (1.56 mol) of resorcin was added, the temperature was increased to 110 ° C., and dehydration was performed for 2 hours under a slightly reduced pressure (92 kPa). During this time, the internal temperature rose from 115 ° C to 118 ° C. Subsequently, the internal temperature was raised to 125 ° C., and dehydration (92 kPa) was performed for 1 hour. Subsequently, the internal temperature was raised to 140 ° C., and dehydration (92 kPa) was performed for 1 hour. Thereafter, the internal temperature was raised to 145 to 150 ° C., and the water was distilled off by keeping the temperature for 1 hour.
Thereafter, 98.8 g of an industrial cashew nut shell liquid (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (oil at normal temperature) was added, and the pressure was reduced to 16 kPa while maintaining the internal temperature at 140 to 150 ° C. to obtain a brown resin composition. 493 g were obtained.
Average molecular weight of resin composition containing cashew nut shell liquid: 2231, softening point: 99 ° C., free p-tert-butylphenol content: 0.0%, free o-phenylphenol content: 1.3%, free resorcinol content: 5 0.6%, cashew nut shell liquid content: 20%.

<Production Example 2>
In Production Example 1, the reaction was carried out in the same manner as in Production Example 1, except that the reaction between phenols and formalin was 65 ° C. for 3 hours, and the amount of resorcin used in the reaction with resorcin was 316.8 g (2.88 mol). Then, 769 g of a brown co-condensation resin was obtained.
Average molecular weight of co-condensation resin: 3116, softening point: 142 ° C, free p-tert-butylphenol content: 0.0%, free o-phenylphenol content: 1.0%, free resorcinol content: 5.0%.

<Example 3>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 160.0 g of the co-condensation resin obtained in Production Example 2 and an industrial cashew nut shell liquid (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (at room temperature) (Oil) 40.0 g. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 1 hour while keeping the internal temperature at 140 to 150 ° C., so that the co-condensation resin and the cashew nut shell liquid were mixed uniformly. Then, it was taken out on a metal vat, cooled to room temperature, and crushed in a mortar to obtain 199.0 g of a brown resin composition containing a cashew nut shell liquid.
Average molecular weight of resin composition containing cashew nut shell liquid: 2884, softening point: 109 ° C., free p-tert-butylphenol: 0.0%, free o-phenylphenol: 0.8%, free resorcinol: 4.1% , Cashew nut shell liquid content: 20%.

<Example 4>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 135.0 g of the co-condensation resin obtained in Production Example 1 and an industrial cashew nut shell solution (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (at room temperature) 15.0 g). Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 1 hour while keeping the internal temperature at 140 to 150 ° C., so that the co-condensation resin and the cashew nut shell liquid were mixed uniformly. Then, it was taken out on a metal vat, cooled to room temperature, and crushed in a mortar to obtain 147.2 g of a brown resin composition containing a cashew nut shell liquid.
Average molecular weight of resin composition containing cashew nut shell liquid: 2077, softening point: 112 ° C., free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.2%, free resorcin: 7.2% , Cashew nut shell liquid content: 10%.

<Example 5>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 85.1 g of the co-condensation resin obtained in Production Example 1 and cashew nut shell liquid for industrial use (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (at room temperature) 4.5 g of oil) were added in order. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 1 hour while keeping the internal temperature at 140 to 150 ° C., so that the co-condensation resin and the cashew nut shell liquid were mixed uniformly. Then, it was taken out on a metal vat, cooled to room temperature, and crushed in a mortar to obtain 88.3 g of a brown resin composition containing a cashew nut shell liquid.
Average molecular weight of resin composition containing cashew nut shell liquid: 2184, softening point: 120 ° C., free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.2%, free resorcinol: 7.5% , Cashew nut shell liquid content: 5%.

<Example 6>
In a four-neck separable flask equipped with a reflux condenser and a thermometer, 140.0 g of the co-condensation resin obtained in Production Example 2 and an industrial cashew nut shell solution (CNSL manufactured by TAN HOA HOP PHAT Co., Ltd.) (at room temperature) (Oil) was added in order. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 1 hour while keeping the internal temperature at 140 to 150 ° C., so that the co-condensation resin and the cashew nut shell liquid were mixed uniformly. Then, it was taken out on a metal vat, cooled to room temperature, and crushed in a mortar to obtain 198 g of a brown resin composition containing a cashew nut shell liquid.
Average molecular weight of resin composition containing cashew nut shell liquid: 3187, softening point: 109 ° C., free p-tert-butylphenol: 0.0%, free o-phenylphenol: 0.7%, free resorcinol: 3.6% , Cashew nut shell liquid content: 30%.

<Comparative Example 1>
To a four-neck separable flask equipped with a reflux condenser and a thermometer, 45.0 g of the co-condensation resin obtained in Production Example 1 and 5.0 g of a naphthenic process oil were added in order. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 2 hours while keeping the internal temperature at 140 to 150 ° C. However, the compatibility with the co-condensation resin was poor, and a part of the process oil remained separated. Thereafter, the resin composition was taken out on a metal vat to obtain 49.5 g of a resin composition containing a separated naphthenic process oil. For analysis / evaluation, a portion without separated oil was selected and used.
Average molecular weight of resin composition containing naphthenic process oil: 1898, softening point: 124 ° C, free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.5%, free resorcinol: 7.3 %, Content of process oil (including separation part): 10%.

<Comparative Example 2>
To a four-neck separable flask equipped with a reflux condenser and a thermometer, 45.0 g of the co-condensation resin obtained in Production Example 1 and 5.0 g of paraffin-based process oil were added in order. Thereafter, the temperature was raised to an internal temperature of 140 ° C., and the mixture was stirred for 2 hours while keeping the internal temperature at 140 to 150 ° C. However, the compatibility with the co-condensation resin was poor, and a part of the process oil remained separated. Thereafter, the resin composition was taken out on a metal vat to obtain 49.2 g of a resin composition containing the separated paraffin-based process oil. For analysis and evaluation, a portion without separated oil was selected and used.
Average molecular weight of resin composition containing paraffin-based process oil: 1722, softening point: 123 ° C, free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.5%, free resorcinol: 7.2 %, Content of process oil (including separation part): 10%.

<Comparative Example 3>
160.0 g of the co-condensed resin obtained in Production Example 1 and 40.0 g of gum rosin were sequentially added to a four-neck separable flask equipped with a reflux condenser and a thermometer. Thereafter, the internal temperature was raised to 140 ° C., and the mixture was stirred for 2 hours while keeping the internal temperature at 140 to 150 ° C., whereby a transparent resin liquid was obtained. Thereafter, the resin composition was taken out on a metal vat and cooled to room temperature. As a result, 196.9 g of a resin composition containing gum rosin, which was partially cloudy, was obtained.
Average molecular weight of resin composition containing gum rosin: 1425, softening point: 122 ° C, free p-tert-butylphenol: 0.0%, free o-phenylphenol: 1.3%, free resorcinol: 7.4%, gum rosin Content: 20%.

  The composition, softening point, and evaluation results of resin uniformity and blocking properties of the resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 3 are shown below. In addition, the uniformity and blocking property of the resin were evaluated as follows.

<Uniformity of resin composition>
：: The compatibility between the co-condensation resin and the softener (cashew nut shell liquid, each oil or gum rosin) was good, and a uniform resin composition solid at room temperature was obtained.
X: The compatibility between the co-condensation resin and the softener was poor, and a solid uniform resin composition at room temperature could not be obtained.

<Blocking property (cohesion) of resin composition>
After each sample was pulverized to a fine powder, about 5 g of each sample was weighed into a plastic bag with a chuck, and allowed to stand in an oven at 40 ° C. and 95% RH for 1 to 3 days to confirm the state of the particles.
◎: No cohesion of particles occurred by 3 days later. The powder was retained.
：: Hardened by 3 days, but easy to unravel.
Δ: Some particles adhered to each other by 3 days later.
×: By one day, the grains were stuck together to form a single body.

2. Production Example of Rubber Composition Using Resin Composition Obtained in the Above Example and Evaluation of Physical Properties <Production of Unvulcanized Rubber Composition Containing Resin Composition Obtained in the Above Example>
As a resin adhesive, SUMIKANOL 620 (Taoka Chemical Industry Co., Ltd.), which is a commercially available resin adhesive as a conventional product, was used to compare the physical properties of the resin compositions prepared in Examples 2, 3, 4 and 6 and the resin composition. Co., Ltd.), the co-condensed resin containing no cashew nut shell liquid, produced in Production Example 2, and an unvulcanized rubber composition were produced by the following method without using a resin adhesive as a blank.

In accordance with the composition shown in Table 2, components other than insoluble sulfur, a vulcanization accelerator and a methylene donor were first added and mixed by a pressure-type kneader manufactured by Toshin, and discharged when the temperature reached 160 ° C (step A). Next, the obtained mixture was mixed with insoluble sulfur, a vulcanization accelerator and a methylene donor using a 6-inch open roll made of Kansai Roll maintained at 60 ° C. to prepare a rubber composition for coating a steel cord (Step B). ).
In Table 3 below, those in which the addition of the resin adhesive was described as A were added in step A, and those in which the addition was described as B were added in step B. Unless otherwise specified, numerical values in Table 2 below represent parts by mass.

The origin of each component in Table 2 is as follows.
・ Natural rubber: SMR-CV60
・ Carbon black: “Seast 300” (HAF-LS grade) manufactured by Tokai Carbon Co., Ltd.
・ Zinc flower: Two kinds of zinc flower made by Shodo Chemical Co., Ltd.
・ Anti-aging agent: “Antioxidant FR” manufactured by Matsubara Sangyo Co., Ltd.
・ Cobalt salt: Cobalt stearate (reagent)
-Insoluble sulfur: "Cristex HS OT-20" manufactured by Flexis
・ Vulcanization accelerator: N, N-dicyclohexyl-2-benzothiazolesulfenamide (reagent)
・ Methylene donor: “Sumikanol 507AP” manufactured by Bara Chemical

<Rubber physical properties test of unvulcanized rubber composition and vulcanized rubber composition>
After the unvulcanized rubber composition obtained as described above was left at room temperature for 24 hours after preparation, it was heated with a 6-inch open roll made of Kansai Roll maintained at 60 ° C., made into a sheet, and left on a metal plate. Cooled to room temperature. Subsequently, using the unvulcanized sample, a Mooney viscosity test (JIS K 6300-1: 2001, measured at 130 ° C., ML (1 + 4)) and a rheometer test (JIS K 6300-2: 2001, 160 ° C, MH, t10, t90).
Further, the unvulcanized sample was vulcanized under the conditions of 160 ° C. and 6 MPa under a pressure of t90 + 5 minutes to prepare a vulcanized rubber sheet having a thickness of 2 mm.
Next, using a rubber test piece prepared from the vulcanized rubber sheet, a tensile test (measured according to JIS K 6251: 2010, measuring a tensile stress M200, a breaking strength Tb and a breaking elongation Eb at 25 ° C.), and dispersing the resin (determination) Criteria: Visually check whether there is any solid foreign matter on the surface of the test piece in the tensile test.No foreign matter: 、, presence of foreign matter: x), and measurement of hardness (JIS K 6253: 2006, measured at 25 ° C.) ). In this test result, the rubber composition to which no resin composition was added (Comparative Example 4) was set to 100, and each was relatively evaluated. Table 3 shows the results.

  As shown in Table 3 above, as a result of the unvulcanized rubber physical property test and the vulcanized rubber physical property test, the rubber composition prepared by blending the resin compositions obtained in Examples 2, 3, 4 and 6 showed a known resin adhesion. The performance was equivalent to that of the agent "SUMIKANOL620", and it was confirmed that each physical property was improved as compared with the rubber composition without the resin composition added.

  Furthermore, the resin composition of the present invention can be added in the step of kneading the filler and the rubber component (the above-mentioned step A), and is carried out at a lower temperature than the step A. It was found that even when the kneaded product, the sulfur component, and the vulcanization accelerator were added during the step of kneading (step B), the same performance as that of the known resin adhesive “SUMIKANOL620” was exhibited (Example 9).

<Evaluation methods and results of initial adhesion and wet heat adhesion of vulcanized rubber compositions containing the resin compositions obtained in the above Examples, Production Examples and Comparative Examples>

  Using each of the unvulcanized rubber compositions obtained as described above, a sample of a rubber-steel cord composite was prepared. In detail, brass-plated steel cords (diameter of about 0.8 mm, 3 × 0.20 + 6 × 0.35 mm structure, brass plating of copper / zinc = 64/36 (mass ratio)) at intervals of 1/10 mm The two sides of the array of five were covered with an unvulcanized rubber sheet having a thickness of about 2 mm made of each of the above unvulcanized rubber compositions, and the cords were laminated in parallel for a peel adhesion test. An unvulcanized sample was prepared. Using the obtained unvulcanized sample, initial adhesion and wet heat adhesion were evaluated by the following methods.

<Initial adhesion>
After the above unvulcanized sample was prepared, it was left at room temperature for 24 hours, and then vulcanized under the conditions of 160 ° C. and 6 MPa under a pressure of t90 + 5 minutes, and a 1 cm × 1 cm × 6 cm rectangular body having 5 steel cords sandwiched by 1 cm. Rubber pieces were obtained. Each rubber piece was subjected to a steel cord pull-out test using an autograph “AGC-X” manufactured by Shimadzu Corporation, and the stress when vertically pulled out at 100 mm / min was used to determine the rubber pull-out strength (kgf ). Further, the rubber coverage of the steel cord after drawing was visually observed and evaluated from 0 to 100%. Measurement and evaluation were performed with N = 10 (pieces), and the average value was determined. The results are shown in Table 4 below.

  As shown in Table 4 above, when the co-condensation resin produced in Production Example 2 containing no cashew nut shell liquid was used as the resin adhesive, the tensile strength was inferior to Comparative Example 4 not using the resin adhesive. There was found. This result is presumed to be due to the fact that the cohesive force of the rubber composition was reduced and the performance as a resin adhesive was not exhibited.

<Wet heat adhesion (adhesion after wet heat aging)>
The unvulcanized sample was prepared, left at room temperature for 24 hours, and then vulcanized under the conditions of 160 ° C. and 6 MPa under a pressure of t90 + 5 minutes, and the vulcanized test piece was steamed at 80 ° C. × 95% RH. After standing for 7 days and 20 days, a pull-out test similar to the above-mentioned initial adhesiveness was performed, and a pull-out strength change rate and a rubber coverage of the steel cord after the pull-out were measured.
The pull-out strength change rate is a change rate (tensile strength after wet heat aging / tensile strength before wet heat aging × 100) when the initial value of tensile strength is 100, and the rubber coverage of the steel cord after drawing is The rubber coverage of the steel cord after drawing was visually observed and evaluated from 0 to 100%.
The above measurement and evaluation were performed with N = 10 (pieces), and the average value was obtained. The results are shown in Table 5 below.

  As shown in Table 5 above, the rubber composition containing the resin composition obtained in Examples 2, 3, 4 and 6 was not subjected to wet heat aging as compared with the rubber composition without the resin adhesive. However, it has been found that the adhesive strength between the rubber and the steel cord is greatly improved, and the performance is equal to or higher than that of the known resin adhesive "SUMIKANOL620".

Claims (6)

In the presence of an alkali, one or more of the following general formulas (1)

(R represents an alkyl group or a phenyl group which may have a branch.)
And in phenol and formaldehyde, represented by reacting give phenol resin, phenol represented by the general formula obtained by reacting the phenol resin and resorcinol (1), from resorcinol and formaldehyde A resin composition comprising a co-condensation resin having a structural unit and a cashew nut shell liquid, wherein the content of the cashew nut shell liquid is 5 to 40% by weight. The resin composition according to claim 1, wherein the phenol represented by the general formula (1) is at least one selected from the group consisting of p-tert-butylphenol, o-phenylphenol, p-tert-octylphenol, and cresol. 3. The resin composition according to claim 1, wherein the phenols represented by the general formula (1) are p-tert-butylphenol and o-phenylphenol. The following general formula (1) including the following steps (I) to (III) in this order:

(R represents an alkyl group or a phenyl group which may have a branch.)
A method for producing a resin composition comprising a co-condensation resin having a structural unit derived from phenols, resorcinol and formaldehyde represented by the formula: and a cashew nut shell liquid.
(I) a step of reacting one or more phenols represented by the general formula (1) with formaldehyde in the presence of an alkali to obtain a phenolic resin.
(II) a step of reacting the phenolic resin with resorcinol to obtain a cocondensation resin having a structural unit derived from phenols, resorcinol and formaldehyde represented by the general formula (1).
(III) a step of mixing the co-condensation resin with a cashew nut shell liquid. The method for producing a resin composition according to claim 4, wherein the steps (II) and (III) are performed at 150 ° C or lower. A rubber composition comprising the resin composition according to claim 1.