WO2016052447A1

WO2016052447A1 - Rubber composition for tire

Info

Publication number: WO2016052447A1
Application number: PCT/JP2015/077400
Authority: WO
Inventors: 淳一山岸; 信一武者; 芳彦金冨
Original assignee: 株式会社ブリヂストン
Priority date: 2014-10-01
Filing date: 2015-09-28
Publication date: 2016-04-07

Abstract

This rubber composition for a tire is obtained by blending a rubber component (A), insoluble sulfur (B), and a co-condensate (C) that has a softening point of 150 °C or less and that contains a p-tert-butylphenol-derived constituent unit represented by formula (1), an o-phenylphenol-derived constituent unit represented by formula (2), and a resorcinol-derived constituent unit represented by formula (3). The blending amount of the insoluble sulfur (B) is 1.0-6.5 parts by mass with respect to 100 parts by mass of the rubber component (A). The blending amount of the co-condensate (C) is 0.1-10 parts by mass with respect to 100 parts by mass of the rubber component (A). The co-condensate (C) can be used as a replacement for p-tert-octylphenol and p-nonylphenol, has a softening point that is lower than the maximum temperature in a rubber processing step, and has excellent dispersibility in rubber.

Description

Rubber composition for tire

The present invention relates to a tire rubber composition using a cocondensate obtained from alkylphenol, resorcin, and the like.

Rubber products such as tires, belts and hoses are reinforced with reinforcing materials such as steel cords and organic fibers. These rubber products are required to firmly bond rubber and a reinforcing material.
For bonding the rubber and the reinforcing material, there is a method using an adhesive. As an example, in the kneading process of rubber, in the kneading process, an adhesive is blended with various other compounding agents and kneaded, by reacting alkylphenols such as p-tert-octylphenol and p-nonylphenol with formalins. It is known that a cocondensate obtained by reacting resorcin with the obtained cocondensate is used as an adhesive in a rubber processing step (see Patent Document 1).
However, p-tert-octylphenol and p-nonylphenol are considered to be SVHC candidate substances stipulated in REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) regulations, which are regulations in the EU, and their use will be restricted in the EU. There is a high possibility of being.

Therefore, it has been proposed to produce an adhesive with a reinforcing material using an alternative compound not listed in the SVHC candidate substances defined in the REACH regulations. As an example, it has been proposed to produce a cocondensate with resorcin using p-tert-butylphenol instead of p-tert-octylphenol.
In addition, reduction of free components in the cocondensate in consideration of the working environment has also been demanded.

Japanese Patent Application Laid-Open No. 06-234824

The present invention relates to a rubber composition after vulcanization without using p-tert-octylphenol and p-nonylphenol, which may be restricted by legal regulations, in rubber products reinforced with a reinforcing material such as steel cord. It is an object of the present invention to provide a rubber composition for tires having excellent crack resistance.

In the rubber product reinforced with a reinforcing material such as a steel cord, the present inventors have added a cocondensate containing a structural unit derived from o-phenylphenol in addition to a structural unit derived from p-tert-butylphenol and resorcin. It has been found that it can be used as an adhesive. Moreover, it discovered that the crack progress property of the rubber composition after vulcanization improved by mix | blending specific amount of specific sulfur with this adhesive agent. The present invention has been made based on these findings.
That is, the tire rubber composition according to the present invention comprises a rubber component (A), insoluble sulfur (B), a structural unit derived from p-tert-butylphenol represented by the following formula (1), the following formula (2) And a co-condensate (C) containing a structural unit derived from resorcin represented by the following formula (3) and having a softening point of 150 ° C. or lower. The amount of the insoluble sulfur (B) is 1.0 to 6.5 parts by mass with respect to 100 parts by mass of the rubber component (A), and the amount of the cocondensate (C) However, they are 0.1 mass part or more and 10 mass parts or less with respect to 100 mass parts of rubber components (A).

According to the present invention, a rubber product reinforced with a reinforcing material such as a steel cord does not use p-tert-octylphenol and p-nonylphenol, which may be restricted by law and regulation, and rubber after vulcanization. It is possible to provide a rubber composition for a tire excellent in crack resistance of the composition.

[Rubber composition for tire]
Hereinafter, the rubber composition for tires according to the embodiment of the present invention will be described in detail.
The tire rubber composition according to this embodiment includes a rubber component (A), insoluble sulfur (B), a structural unit derived from p-tert-butylphenol represented by the following formula (1), the following formula (2): And a co-condensate (C) containing a structural unit derived from resorcin represented by the following formula (3) and having a softening point of 150 ° C. or lower. The amount of the insoluble sulfur (B) is 1.0 to 6.5 parts by mass with respect to 100 parts by mass of the rubber component (A), and the amount of the cocondensate (C) is The amount of the rubber component (A) is 0.1 parts by mass or more and 10 parts by mass or less based on 100 parts by mass.

<Rubber component (A)>
The rubber component (A) to be blended in the tire rubber composition according to the embodiment of the present invention includes natural rubber, epoxidized natural rubber, deproteinized natural rubber and other modified natural rubber, as well as polyisoprene rubber (IR). Styrene / butadiene copolymer rubber (SBR), polybutadiene rubber (BR), acrylonitrile / butadiene copolymer rubber (NBR), isoprene / isobutylene copolymer rubber (IIR), ethylene / propylene-diene copolymer rubber (EPDM), halogen Various synthetic rubbers such as hydrogenated butyl rubber (HR) are exemplified. Of these, preferably used are highly unsaturated rubbers such as natural rubber, polyisoprene rubber, styrene / butadiene copolymer rubber, polybutadiene rubber, and particularly preferably natural rubber and / or polyisoprene rubber. . It is also effective to combine several rubber components such as a combination of natural rubber and styrene / butadiene copolymer rubber, a combination of natural rubber and polybutadiene rubber.

Examples of natural rubber include natural rubber of grades such as RSS # 1, RSS # 3, TSR20, and SIR20. As the epoxidized natural rubber, those having a degree of epoxidation of 10 to 60 mol% are preferable, and examples thereof include ENR25 and ENR50 manufactured by Kumpoulangrie. As the deproteinized natural rubber, a deproteinized natural rubber having a total nitrogen content of 0.3% by mass or less is preferable. As the modified natural rubber, a modified material containing a polar group obtained by reacting natural rubber with N, N-dialkylaminoethyl acrylate such as 4-vinylpyridine, N, N-diethylaminoethyl acrylate, 2-hydroxy acrylate or the like in advance. Natural rubber is preferably used.

Examples of the styrene-butadiene copolymer rubber (SBR) include emulsion polymerization SBR and solution polymerization SBR described on pages 210 to 211 of “Rubber Industry Handbook <Fourth Edition>” edited by the Japan Rubber Association. . Among these, it is particularly preferable to use solution polymerization SBR.
As a commercially available solution polymerized SBR, a solution polymerized SBR having a molecular terminal modified with 4,4′-bis- (dialkylamino) benzophenone such as “Nipol (registered trademark) NS116” manufactured by Nippon Zeon Co., Ltd., manufactured by JSR A solution-polymerized SBR having a molecular end modified with a tin halide compound such as “SL574” or a silane-modified solution-polymerized SBR such as “E10” or “E15” manufactured by Asahi Kasei Corporation is preferably used.
Further, any one of a silane compound such as a lactam compound, an amide compound, a urea compound, an N, N-dialkylacrylamide compound, an isocyanate compound, an imide compound, a trialkoxysilane compound having an alkoxy group, or an aminosilane compound is used alone. Alternatively, two or more different compounds such as a silane compound having a tin compound and an alkoxy group, and an alkylacrylamide compound and an silane compound having an alkoxy group are used, and the molecular ends are modified by nitrogen and tin at the molecular ends. In particular, solution polymerization SBR having any one of silicon, silicon, or a plurality of these elements is preferably used.

Examples of polybutadiene rubber (BR) include solution polymerization BR such as high cis BR with 90% or more of cis 1,4 bond and low cis BR with cis bond of around 35%, and low cis with high vinyl content. BR is preferably used. As a commercial product of BR, tin-modified BR such as “Nipol (registered trademark) BR 1250H” manufactured by Nippon Zeon Co., Ltd. is preferably used.
Also, 4,4′-bis- (dialkylamino) benzophenone, tin halide compound, lactam compound, amide compound, urea compound, N, N-dialkylacrylamide compound, isocyanate compound, imide compound, trialkoxy having an alkoxy group Two types of different compounds such as a silane compound such as a silane compound, an aminosilane compound alone, a silane compound having a tin compound and an alkoxy group, or a silane compound having an alkylacrylamide compound and an alkoxy group. In particular, solution polymerization BR having nitrogen, tin, silicon, or a plurality of these elements at the molecular ends obtained by modifying the molecular ends is particularly preferably used.
The rubber component preferably contains natural rubber, and the above-mentioned BR is usually used by mixing with natural rubber. The proportion of natural rubber in the rubber component (A) is preferably 70% by mass or more.

<Insoluble sulfur (B)>
The rubber composition for tires according to the present embodiment needs to contain insoluble sulfur as a vulcanizing agent. The compounding quantity of insoluble sulfur (B) needs to be 1.0 mass part or more and 6.5 mass parts or less as a sulfur content with respect to 100 mass parts of rubber components. If the amount of insoluble sulfur (B) is 1.0 part by mass or more, the wet heat adhesiveness required for the vulcanized rubber is obtained, and if it is 6.5 parts by mass or less, it is melted in the vulcanized rubber. Crack growth resistance is obtained. In this respect, the amount of insoluble sulfur (B) is preferably 1.5 parts by mass or more and 6.5 parts by mass or less, and more preferably 2 parts by mass or more and 6.5 parts by mass or less.
As the vulcanizing agent, powdered sulfur, precipitated sulfur, colloidal sulfur, highly dispersible sulfur and the like may be blended in addition to insoluble sulfur (B).

<Cocondensate (C)>
The cocondensate (C) includes a structural unit derived from p-tert-butylphenol represented by the following formula (1), a structural unit derived from o-phenylphenol represented by the following formula (2), and the following formula (3 The structural unit derived from resorcin represented by this.

These structural units are usually contained in the main chain of the cocondensate, but may also be contained in the side chain. Among these structural units, when the structural unit derived from o-phenylphenol (2) is not included, the softening point becomes high, and a problem of poor dispersibility occurs when blended with rubber during kneading. It becomes unsuitable as an adhesive between rubber and reinforcing material used in rubber. Moreover, when the structural unit (3) derived from resorcin is not contained, the ability as an adhesive between the rubber and the reinforcing material used by blending with rubber during kneading is not sufficiently exhibited. Furthermore, when the structural unit (1) derived from p-tert-butylphenol is not included, the cost as a cocondensate becomes very high, and the cocondensate cannot be obtained industrially advantageously.

The content ratio of these structural units is preferably 0.5 to 6 moles of the structural unit (2) derived from o-phenylphenol with respect to 1 mole of the structural unit (1) derived from p-tert-butylphenol. More preferably, the molar amount is 1.5 to 6 times. When the amount is less than 0.5 times mol, the softening point may be too high and the above-mentioned problem may occur. When the amount is more than 6 times mol, the raw material cost of the cocondensate is increased, and the present invention is advantageous industrially. It may become impossible to produce the cocondensate according to.
The structural unit (3) derived from resorcin is usually 0.5 to 2 parts per 1 mol of the total amount of the structural unit (1) derived from p-tert-butylphenol and the structural unit (2) derived from o-phenylphenol. 0 times mole is contained. When the amount is less than 0.5 times mol, the ability as an adhesive between the rubber and the reinforcing material to be used by mixing with rubber during kneading may not be sufficiently exhibited. It may be difficult to manufacture.

These structural units are usually connected by a linking group such as an alkyl group and / or an alkyl ether group derived from an aldehyde used in the reaction. Among them, the linking group is preferably a methylene group and / or a dimethylene ether group derived from formaldehyde. The linking group is usually contained in an amount of 1 to 2 moles per 1 mole of the total amount of the structural unit (1) derived from p-tert-butylphenol and the structural unit (2) derived from o-phenylphenol.
The ratio of these structural units and bonding groups can be determined, for example, by analyzing the cocondensate using ¹ H-NMR. Specifically, a method is exemplified in which the cocondensate is analyzed by ¹ H-NMR, and among the obtained analysis results, the ratio is determined from the proton integral value derived from each structural unit or bonding group.
The cocondensate (C) that can be used in the rubber composition for tires according to the embodiment of the present invention is a structural unit other than structural units derived from p-tert-butylphenol, o-phenylphenol, and resorcin, if necessary. Can be included. Examples of such structural units include structural units derived from various alkylphenols used as raw materials for cocondensates generally used as adhesives used in rubber processing steps.

The softening point of the cocondensate (C) needs to be 150 ° C. or less. The softening point is preferably in the range of 80 ° C to 150 ° C, more preferably in the range of 80 ° C to 140 ° C, and particularly preferably in the range of 90 ° C to 120 ° C.
When the softening point of the co-condensate (C) is higher than 150 ° C., a problem of poor dispersibility occurs when blended with the tire rubber composition during kneading in the tire rubber composition. In some cases, it is not suitable as an adhesive between rubber and a reinforcing material. If it is lower than 80 ° C., blocking may occur during storage.

In the tire rubber composition according to this embodiment, the cocondensate (C) is required to be contained in an amount of 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component (A).
When the blending amount of the cocondensate (C) is less than 0.1 parts by mass with respect to 100 parts by mass of the rubber component (A), sufficient adhesion (wet heat adhesion) cannot be obtained.
When the amount of the co-condensate (C) exceeds 10 parts by mass with respect to 100 parts by mass of the rubber component (A), the adhesive reaction during vulcanization proceeds excessively, resulting in adhesiveness (wet heat adhesion). descend.
From the above viewpoint, the cocondensate (C) is preferably 0.2 parts by mass or more and 8 parts by mass or less, and more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component (A). 6 parts by mass or less.

The total amount of unreacted monomers (free p-tert-butylphenol, o-phenylphenol and resorcin) and residual solvent contained in the cocondensate (C) is preferably 15% by mass or less. By setting the content to 15% by mass or less, the odor during the kneading operation can be reduced, which is environmentally preferable.
In particular, the content of free resorcin is preferably 12% by mass or less. When the content of free resorcin is 12% by mass or less, when the cocondensate (C) is added to the rubber, the transpiration of resorcin that occurs during kneading into the rubber is improved, so that the working environment is greatly improved, which is particularly preferable. .
The total amount of unreacted monomers p-tert-butylphenol and o-phenylphenol other than free resorcin and residual solvent that may be used in the reaction contained in the cocondensate (C) is 5% by mass or less. Preferably there is. When the content is 5% by mass or less, the odor is reduced and the volatile organic compound is reduced, which is preferable for the environment, and more preferably 3% by mass or less.
From the above viewpoint, the total amount of the unreacted monomer other than free resorcin and the residual solvent contained in the tire rubber composition according to the present invention is preferably 0.20% by mass or less, and 0.17% by mass with respect to the rubber component. % Or less is more preferable.

<Filler>
The tire rubber composition according to the present embodiment may contain a filler as necessary. The filler is preferably at least one selected from carbon black and inorganic filler. In this embodiment, carbon black is not included in the inorganic filler.
In the rubber composition according to this embodiment, the total amount of carbon black and the inorganic filler is preferably 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component (A). If it is 5 parts by mass or more, it is preferable from the viewpoint of securing the elastic modulus, and if it is 100 parts by mass or less, it is preferable from the viewpoint of improving low heat generation. From the above viewpoint, the total amount of the inorganic filler and the carbon black is more preferably 20 parts by mass or more and 80 parts by mass or less, and still more preferably the rubber component (A) with respect to 100 parts by mass of the rubber component (A). ) 20 parts by mass or more and 70 parts by mass or less, and particularly preferably 30 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass.

<Carbon black>
The rubber composition for a tire according to the present embodiment can enjoy the effect of suppressing charging by lowering the electrical resistance by containing carbon black.
Examples of carbon black include high, medium or low structure SAF, ISAF, IISAF, N339, HAF, FEF, GPF, SRF grade carbon black, especially SAF, ISAF, IISAF, N339, HAF, FEF grade carbon black. Is preferably used. The nitrogen adsorption specific surface area (measured in accordance with N ₂ SA, JIS K 6217-2: 2001) of carbon black is preferably 30 to 250 m ² / g. Carbon black may be used individually by 1 type from what was mentioned above, and may be used in combination of 2 or more type.

<Inorganic filler>
An inorganic filler can be mix | blended with the rubber composition for tires which concerns on this invention as needed. The inorganic filler used in the present embodiment is at least one selected from silica and an inorganic compound represented by the following general formula (I).
dM ¹ · xSiO _y · zH ₂ O (I)
Here, in the general formula (I), M ¹ is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium, and zirconium, an oxide or hydroxide of these metals, and a hydrate thereof. Or at least one selected from carbonates of these metals, and d, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10 is there.
In the general formula (I), when both x and z are 0, the inorganic compound is at least one metal, metal oxide or metal hydroxide selected from aluminum, magnesium, titanium, calcium and zirconium. It becomes.

In the embodiment of the present invention, the above-mentioned inorganic filler is preferably silica from the viewpoint of low rolling property. In the present embodiment, from the viewpoint of improving the reinforcing property and low fuel consumption of the tire rubber composition, the amount of silica is 1 part by mass or more and 65 parts by mass with respect to 100 parts by mass of the rubber component (A). Preferably, the amount is 10 parts by mass or more and 40 parts by mass or less.
When silica is used as the inorganic filler, the BET specific surface area (measured in accordance with ISO 5794/1) of silica is preferably 40 to 350 m ² / g. Silica having a BET surface area within this range has an advantage that both rubber reinforcement and dispersibility in the rubber component (A) can be achieved. From this viewpoint, silica having a BET surface area in the range of 80 to 350 m ² / g is more preferable, and silica having a BET surface area in the range of 120 to 350 m ² / g is particularly preferable.
Commercially available products can be used as silica, and wet silica, dry silica, and colloidal silica are particularly preferable, and wet silica is particularly preferable.
Examples of such silica include “Ultra Gil (registered trademark) VN3” (BET specific surface area = 175 m ² / g) manufactured by Degussa, “Ultra Gil (registered trademark) 360”, “Ultra Gil (registered trademark) 7000”. "Zeosil (registered trademark) 115GR", "Zeosil (registered trademark) 1115MP", "Zeosil (registered trademark) 1205MP", "Zeosil (registered trademark) Z85MP", manufactured by Rhodia, "Nipseal (registered trademark)" manufactured by Tosoh Silica ) AQ "and the like are preferably used.

When an inorganic compound represented by the general formula (I) is blended as an inorganic filler, alumina monohydrate such as alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina, boehmite and diaspore ( Al ₂ O ₃ .H ₂ O), gibbsite, bayerite and other aluminum hydroxide [Al (OH) ₃ ], aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO _3), talc _{_{(3MgO · 4SiO 2 · H 2}} O), attapulgite _{_{(5MgO · 8SiO 2 · 9H 2}} O), titanium white _(TiO 2), titanium black _{(TiO 2n- 1} ), calcium oxide (CaO), calcium hydroxide [Ca (OH) ₂ ], aluminum magnesium oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O ₃ · 2SiO ₂ ), kaolin (Al ₂ O ₃ · 2SiO ₂ · 2H ₂ O), pyrophyllite (Al ₂ O ₃ · 4SiO ₂ · H ₂ O), bentonite (Al ₂ O ₃ · 4SiO ₂ · 2H ₂ O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ · 3SiO ₄ · 5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate ( Ca ₂ SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide _{_{[ZrO (OH) 2 · nH}} 2 O], zirconium carbonate _{_{[Zr (CO 3) 2]}} , various zeolites Hydrogen for correcting the charge, such as crystalline aluminosilicates including alkali metal or alkaline earth metal can be used as.
Further, it is preferable that M ¹ in the general formula (I) is at least one selected from aluminum metal, aluminum oxide or hydroxide, and hydrates thereof, or aluminum carbonate. More preferred is aluminum oxide.
Examples of the aluminum hydroxide that can be blended in the tire rubber composition according to the present invention include aluminum hydroxide having a nitrogen adsorption specific surface area of 5 to 250 m ² / g and a DOP oil supply amount of 50 to 100 ml / 100 g.
These inorganic compounds represented by general formula (I) may be used alone or in combination of two or more.
The inorganic filler in the present invention may be used alone or in combination with silica and one or more inorganic compounds represented by the general formula (I).

<Silane coupling agent>
When the rubber composition for tires according to the present invention is blended with an inorganic filler containing silica, a silane coupling agent is blended for the purpose of further improving the reinforcing property and fuel efficiency of the tire rubber composition. can do.
Examples of silane coupling agents include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and bis (2-triethoxysilyl). Ethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltri Methoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarba Yl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzoyltetrasulfide, 3-triethoxy Silylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetra Sulfide, dimethoxymethylsilylpropylbenzothiazolyl tetrasulfide, 3-octanoylthiopropyltriethoxysilane, etc. Among them, bis (3-triethoxysilylpropyl) polysulfide, 3-octanoylthiopropyltriethoxysilane and 3-trimethoxysilylpropylbenzothiazyl tetrasulfide are preferable from the viewpoint of improving the reinforcing property. .
One of these silane coupling agents may be used alone, or two or more thereof may be used in combination.

From the viewpoint of the effect as a coupling agent and prevention of gelation, the preferable blending amount of this silane coupling agent is such that the mass ratio (silane coupling agent / silica) is (1/100) to (20/100). It is preferable. If it is (1/100) or more, the effect of improving the low heat buildup of the rubber composition for tires will be exhibited more suitably, and if it is (20/100) or less, the cost of the rubber composition for tires will be reduced. This is because the economy is improved. Further, a mass ratio (3/100) to (20/100) is more preferable, and a mass ratio (4/100) to (10/100) is particularly preferable.

<Bismaleimide compound>
It is preferable that a bismaleimide compound is blended in the tire rubber composition according to the present embodiment. The bismaleimide compound functions as a part of the vulcanization system together with insoluble sulfur (B) as a vulcanizing agent preferably contained in the tire rubber composition of the present embodiment.
As the bismaleimide compound that can be blended in the tire rubber composition according to this embodiment, it is preferable to use one or more selected from compounds represented by the following formula (4).

In the formula, X represents an alkylene group having 2 to 4 carbon atoms, a phenylene group, or a divalent hydrocarbon group having 6 to 29 carbon atoms having 1 to 4 aromatic rings, and R ⁴ to R ⁷ are each independently Represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a —NH ₂ group or a —NO ₂ group.

In the formula (4), examples of the alkylene group having 2 to 4 carbon atoms as X include an ethylene group, a propylene group, a propane-2,2-diyl group, and the like.
Examples of the C6-C29 divalent hydrocarbon group having 1 to 4 aromatic rings include a methylene bis (phenylene) group, a phenylene bis (methylene) group, and a phenoxyphenyl group. Further, this aromatic ring may be bonded by —O—, —S—, —SS—, —SO ₂ — or the like. Among the above X, a hydrocarbon group having 8 to 17 carbon atoms having 1 or 2 phenylene group or aromatic ring is preferable, and a hydrocarbon having 8 to 13 carbon atoms having 1 or 2 phenylene group or aromatic ring. Groups are more preferred.

In the formula (4), X may have a substituent. Examples of the substituent include an alkyl group having 1 to 3 carbon atoms, —NH ₂ , —NO ₂ , —F, —Cl, —Br and the like.

In the formula (4), examples of the alkyl group having 1 to 5 carbon atoms represented by R ⁴ to R ⁷ include a methyl group, an ethyl group, and a propyl group.

Preferable examples of the bismaleimide compound include, for example, N, N′-1,2-ethylene bismaleimide, N, N′-1,2-propylene bismaleimide, 4,4′-bismaleimide diphenylmethane, N, N ′. -M-phenylenebismaleimide, N, N '-(4,4-diphenyl-methane) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane, m-phenylenebis (methylene) bismaleimide, m-phenylenebis (methylene) biscitraconimide, 1,1 ′-(methylenedi-4,1-phenylene) bismaleimide It is done. These bismaleimide compounds may be used alone or in combination of two or more. Of these, N, N′-m-phenylenebismaleimide and N, N ′-(4,4-diphenyl-methane) bismaleimide are more preferable.

In the tire rubber composition according to the present embodiment, the blending ratio of the bismaleimide compound is preferably 0.1 parts by mass or more and 5.5 parts by mass or less with respect to 100 parts by mass of the rubber component (A). When the blending amount of the bismaleimide compound is 0.1 parts by mass or more and 5.5 parts by mass or less, the elastic modulus can be increased and wet heat adhesiveness can be improved. From this viewpoint, the blending amount of the bismaleimide compound is more preferably 0.1 parts by mass or more and 5 parts by mass or less.

<Organic cobalt compounds>
The tire rubber composition according to the present embodiment preferably contains an organic cobalt compound. Examples of the organic cobalt compound that can be blended include acid cobalt salts such as cobalt versatate, cobalt neodecanoate, cobalt rosinate, cobalt naphthenate, and cobalt stearate, and fatty acid cobalt / boron complex compounds (for example, trade name “Manobond”). C (registered trademark) "(manufactured by Rhodia).
The compounding amount of the organic cobalt compound can be 0.01 parts by mass or more and 0.08 parts by mass or less, preferably 0.02 parts by mass with respect to 100 parts by mass of the rubber component (A). The amount can be made 0.07 parts by mass or less. In this embodiment, crack progress resistance can be improved by making the compounding quantity of an organic cobalt compound into the said range using a cocondensate (C).

<Vulcanization accelerator>
The tire rubber composition according to the present embodiment preferably contains a vulcanization accelerator. More specific examples of the vulcanization accelerator that can be blended include N-cyclohexyl-2-benzothiazolylsulfenamide, N-ter-butyl-2-benzothiazylsulfenamide, N-tert-butyl- And at least one selected from 2-benzothiazolylsulfenimide and N, N-di (2-ethylhexyl) -2-benzothiazolylsulfenamide. Among these, it is preferable to use N-cyclohexyl-2-benzothiazolylsulfenamide.
Although the compounding quantity of a vulcanization accelerator is not specifically limited, The range of 0.5 to 3 mass parts is preferable per 100 mass parts of rubber components. Among these, a range of 0.5 parts by mass or more and 1.2 parts by mass or less is particularly preferable.

<Zinc oxide>
Although the usage-amount of zinc oxide is not specifically limited, The range of 3 to 15 mass parts is preferable per 100 mass parts of rubber components. Among these, a range of 5 parts by mass or more and 10 parts by mass or less is particularly preferable.

<Rust preventive>
The tire rubber composition according to the present embodiment preferably contains a rust preventive agent. As a rust preventive agent which can be mix | blended, the nitrogen-containing cyclic compound which has a structure where at least 1 carbon atom of the cyclic compound of carbon number 5 or less was substituted by the nitrogen atom is included. In the present embodiment, the nitrogen-containing cyclic compound does not include a benzene ring and a cyclic compound containing sulfur.
Examples of the rust preventive agent that can be blended in the present embodiment include imidazole compounds and triazole compounds, among which 1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4. It is preferably at least one selected from -triazole, 4-amino-1,2,4-triazole, and imidazole.
In the present embodiment, by using the co-condensate (C), the compounding amount of the rust inhibitor is 0.02 parts by mass or more and 12 parts by mass or less with respect to 100 parts by mass of the rubber component (A). it can. From the above viewpoint, the blending amount of the rust inhibitor is more preferably 0.1 parts by mass or more and 3 parts by mass or less.

<Methylene donor compound>
The tire rubber composition according to this embodiment may contain a methylene donor compound. As methylene donor compounds that can be blended, they are usually used in the rubber industry such as hexakis (methoxymethyl) melamine (HMMM), hexamethylenetetramine (HMT), pentakis (methoxymethyl) methylolmelamine, tetrakis (methoxymethyl) dimethylolmelamine and the like. Can be mentioned. Among them, hexakis (methoxymethyl) melamine alone or a mixture containing it as a main component is preferable. These methylene donor compounds can be used alone or in combination of two or more, and the blending amount thereof is 0.5 parts by mass or more and 4 parts by mass or less with respect to 100 parts by mass of the rubber component (A). The range is preferable, and the range of 1 part by mass to 3 parts by mass is more preferable.

<Hydrocarbon resin>
The rubber composition for tires according to the present embodiment includes, as necessary, an alicyclic hydrocarbon resin, an aliphatic hydrocarbon resin, and an aromatic hydrocarbon resin in addition to the cocondensate (C). You may mix | blend the hydrocarbon resin chosen 1 or more types. Here, the alicyclic hydrocarbon resin refers to a petroleum resin produced mainly from cyclopentadiene and / or dicyclopentadiene obtained by dimerizing cyclopentadiene extracted from a C5 fraction of petroleum. An aliphatic hydrocarbon resin refers to a petroleum resin produced using a C5 fraction of petroleum as a main raw material, and an aliphatic hydrocarbon resin refers to a petroleum produced using a C9 fraction of petroleum as a main raw material. Refers to resin.
Of these hydrocarbon resins, a dicyclopentadiene resin (DCPD resin) produced from a high-purity dicyclopentadiene obtained by dimerizing cyclopentadiene as a main raw material is preferable from the viewpoint of enhancing rubber reinforcement.
Preferred examples of the dicyclopentadiene resin include quinton 1000 series (Quinton 1105, quinton 1325, quinton 1340) manufactured by Nippon Zeon.
The amount of the hydrocarbon resin used is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component.

<Other additives>
In the tire rubber composition according to the embodiment of the present invention, various chemicals commonly used in the rubber industry, for example, a vulcanization retarder, process oil, aging, as long as the effects of the present invention are not impaired. An inhibitor, an organic acid, etc. can be mix | blended.
(Vulcanization retarder)
Examples of the vulcanization retarder that can be blended in the tire rubber composition according to this embodiment include phthalic anhydride, benzoic acid, salicylic acid, N-nitrosodiphenylamine, N- (cyclohexylthio) -phthalimide (CTP), and sulfonamide derivatives. , Diphenylurea, bis (tridecyl) pentaerythritol-diphosphite and the like, and N- (cyclohexylthio) -phthalimide (CTP) is preferably used.

(Process oil)
As the process oil used as a softening agent that can be blended in the tire rubber composition according to this embodiment, an aromatic oil is used from the viewpoint of compatibility with SBR. In addition, naphthenic oil or paraffinic oil is used from the viewpoint of emphasizing low temperature characteristics. The amount used is preferably 0 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component, and if it is 100 parts by mass or less, the tensile strength and low fuel consumption (low heat generation) of the vulcanized rubber are deteriorated. Can be suppressed.

(Anti-aging agent)
Antiaging agents that can be blended in the rubber composition for tires according to this embodiment include those described on pages 436 to 443 of “Rubber Industry Handbook <Fourth Edition>” edited by the Japan Rubber Association. Among these, for example, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, N-isopropyl-N′-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N ′ -Phenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, high-temperature condensate of diphenylamine and acetone.
The amount of the antioxidant used is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.3 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the rubber component.

(Organic acid)
Examples of organic acids that can be blended in the tire rubber composition according to this embodiment include stearic acid, palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, capric acid, pelargonic acid, caprylic acid, and enanthate. Examples thereof include saturated fatty acids such as acid, caproic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, and nervonic acid, and resin acids such as rosin acid and modified rosin acid.
In the method for producing a tire rubber composition according to this embodiment, among the organic acids, 50 mol% or more of the organic acid must be stearin since it is necessary to sufficiently function as a vulcanization acceleration aid. An acid is preferred. 50 mol% or less in the organic acid may be rosin acid (including modified rosin acid) and / or fatty acid contained when the styrene-butadiene copolymer is prepared by emulsion polymerization.

[Method for Producing Cocondensate (C)]
The method for producing a cocondensate according to the present invention includes the following steps in the following order.
(A) A step of reacting a mixture of p-tert-butylphenol and o-phenylphenol with formaldehyde in the presence of alkali to obtain a resol-type condensate (b) with respect to the total amount of p-tert-butylphenol and o-phenylphenol A step of further reacting 0.8 times mole or more of resorcin

The ratio of o-phenylphenol in the mixture of p-tert-butylphenol and o-phenylphenol used in step (a) (hereinafter, these two types of phenols may be collectively referred to as “phenol derivatives”) is particularly Although not limited, it is preferably 35 mol% to 85 mol%, more preferably 40 mol% to 85 mol%, and further preferably 60 mol% to 85 mol%, based on the total amount of the phenol derivative. preferable. When the amount is less than 35 mol%, the softening point of the resulting cocondensate becomes high, and dispersion may be poor when kneaded with the rubber component. If it exceeds 85 mol%, a large amount of expensive o-phenylphenol is required, and it may be impossible to produce a cocondensate in an industrially advantageous manner. In addition, the mixture of p-tert-butylphenol and o-phenylphenol in the present invention is a mixture mixed in advance before being charged into the reactor, and separately charged into the reactor, resulting in the mixture in the reactor. Also included are.

As the formaldehyde used in the step (a), in addition to formaldehyde itself, a formalin that is an aqueous solution, or a compound that easily generates formaldehyde such as paraformaldehyde or trioxane can be used. The molar ratio of formaldehyde charged is not particularly limited, but it is preferably 1 to 3 times by mole, more preferably 1.5 to 2.5 times by mole, based on the total amount of phenol derivatives. When the amount is less than 1 mole, unreacted monomers may increase and odor and volatile organic compounds may increase. Further, when the amount is more than 3 times mole, a large amount of formaldehyde remains unreacted, so that the resin may have a three-dimensional structure and the softening point may be increased.

As the alkali, in addition to hydroxides or carbonates of alkali metals or alkaline earth metals, those used for producing ordinary resol-type condensates such as ammonia and amines can be used. Specific examples of the alkali metal or alkaline earth metal hydroxide or carbonate include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and potassium carbonate. Among these, sodium hydroxide and potassium hydroxide are preferable. These alkalis can be used in the form of a solid or an aqueous solution, but it is preferable to use an aqueous solution in terms of reactivity and handling. When an aqueous solution is used, the concentration is usually 10% by mass to 50% by mass. The alkali charge molar ratio is not particularly limited, but is preferably in the range of 0.03 to 0.6 times mol, more preferably in the range of 0.03 to 0.3 times mol with respect to the total amount of the phenol derivative.

The reaction of step (a), that is, the reaction of a mixture of p-tert-butylphenol and o-phenylphenol with formaldehyde in the presence of an alkali can also be carried out in a solvent. The solvent to be used is not particularly limited, and water, alcohol, aromatic hydrocarbon and the like can be used. More specifically, water, methanol, ethanol, propanol, butanol, toluene, xylene, ethylbenzene, cumene, monochlorobenzene and the like are exemplified. Of these, water, toluene, and xylene are preferable. These solvents can be used alone or in combination of two or more. When a solvent is used, it is usually used in an amount of 0.4 to 4 times (for example, 0.4 to 2 times) the total amount of phenol derivatives. The reaction in the step (a) is usually carried out at a reaction temperature of 40 to 100 ° C. and a reaction time of 1 to 48 hours (eg 1 to 8 hours).

The resol-type condensate obtained by such a reaction may be used as it is in the reaction of step (b) without neutralizing the used alkali, that is, the reaction with resorcin, or by adding an acid to neutralize the alkali. It may be used after being summed. The type of acid used for neutralization is not particularly limited, and examples include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, p-toluenesulfonic acid, and the like. These acids may be used alone or in combination of two or more. At this time, the total amount of the acid used is not particularly limited, but it is preferable to use an equivalent amount (based on the amount of substance) of the acid that is normally used. In addition, in order to remove unreacted formaldehyde and inorganic salts generated by neutralization, a resol-type condensate may be extracted and washed using an organic solvent that is not miscible with water as necessary. Good.

In the step (b), the charged molar ratio of resorcin when reacting the obtained resole-type condensate with resorcin must be 0.5 times mol or more, preferably 0. The amount is 8 to 4.0 times mol, more preferably 0.8 to 2.0 times mol, and still more preferably 1.0 to 2.0 times mol. If it is more than 4.0 moles, volatility may be a problem because a large amount of unreacted resorcin remains. If it is lower than 0.5 mol, the reaction will not be completed and the original performance will not be achieved, or the reaction between resol-type condensates will proceed preferentially, and the resulting cocondensate will be polymerized, resulting in a softening point. May not be 150 ° C. or lower.

Although the reaction between the resole-type condensate and resorcin can be carried out without using a solvent, the presence of a solvent more than 0.2 mass times the total amount of p-tert-butylphenol and o-phenylphenol When carried out below, free resorcin can be reduced to 12% by mass or less, which is preferable. More preferably, the reaction is carried out in the presence of 0.4 to 4.0 times by mass, particularly preferably 0.4 to 2.0 times by mass of solvent with respect to the total amount of p-tert-butylphenol and o-phenylphenol. If less than 0.2 mass times, the reaction between resole-type condensates may proceed preferentially over the reaction between resorcin and resole-type condensates, and the resulting cocondensate may be polymerized, Free resorcin cannot be reduced to 12% by mass or less. In addition, the reaction proceeds even when used in an amount of 4.0 mass times or more, but the volumetric efficiency is lowered and the cocondensate cannot be produced economically advantageously.

The usable solvent is not particularly limited, and examples thereof include alcohols, ketones, and aromatic hydrocarbons. More specifically, methanol, ethanol, propanol, butanol, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, toluene, xylene, ethylbenzene, cumene, monochlorobenzene and the like are exemplified. Among these, ketones and aromatic hydrocarbons are preferable, and methyl isobutyl ketone, toluene, and xylene are more preferable. These solvents can be used alone or in combination of two or more as required. Moreover, the solvent used when manufacturing a resol type condensate may be used for this solvent as it is, and a new solvent may be added suitably.

The reaction between the resole-type condensate and resorcin is not particularly limited, but is usually carried out at a reaction temperature of 40 to 150 ° C. and a reaction time of 1 to 48 hours (eg, 1 to 8 hours).
In order to reduce the content of free resorcin contained in the cocondensate to 12% by mass or less, before carrying out the solvent removal step described later, the content of free resorcin is 120 ° C. or higher until the content of free resorcin in the reaction mixture becomes 12% by mass or less It is preferable to carry out the reaction. If more than 12% by mass of free resorcin remains in this reaction stage, it is difficult to implement industrially at a high temperature and a high degree of vacuum even if it is attempted to remove free resorcin at the same time until it becomes less than 12% by mass in the solvent removal step described later. Conditions are necessary, and the cocondensate obtained at this time is colored by heat or polymerization proceeds. As a result, the softening point exceeds 150 ° C., and is used by blending with rubber during kneading. Unsuitable as an adhesive between rubber and metal cord.
The reaction is performed at 120 ° C or higher as long as it is 120 ° C or higher at any time during the reaction. For example, the reaction is started at less than 120 ° C in the initial stage of reaction, and then gradually heated to 120 ° C or higher. The method etc. which are made are illustrated. If the reaction temperature never exceeds 120 ° C., free resorcin in the reaction mixture does not become 12% by mass or less. In addition, as described above, when this reaction is carried out in the absence of a solvent of 0.2 mass times or more, the resulting cocondensate is polymerized, or the free resorcin content is not 12 mass% or less. The reaction mixture refers to everything contained in the reaction vessel, such as resole-type condensate, resorcin, solvent, etc., which are the raw materials for this reaction, and the resorcin content in the reaction mixture can be quantified by analysis using, for example, a gas chromatograph. is there. In order to reduce the free resorcin content, a method of simply reducing the amount of raw material resorcin used is also conceivable. However, when produced by this method, the raw material resorcin is insufficient during the reaction, and instead, the resorcin site in the cocondensate is further increased. Since it reacts and polymerizes, the softening point becomes very high.

In the reaction between the resole-type condensate and resorcin in step (b), the reaction rate tends to be slow if water is present in the system, and the reaction rate is reduced by the water generated by the reaction between the resole-type condensate and resorcin. Therefore, it is preferable to carry out the reaction while dehydrating for the purpose of promoting the reaction. In addition, in this dehydration reaction, water generated in the reaction is sufficiently dehydrated, so that it is dehydrated under reduced pressure at the beginning of the reaction, and then the internal temperature is set to 120 ° C. or higher. Is preferred.
When a solvent is used for the reaction between the resole-type condensate and resorcin, the solvent used in the reaction is usually removed after the reaction. The conditions for removing the solvent are not particularly limited. For example, the solvent removal is performed at 120 to 160 ° C. under a reduced pressure of 45 to 10 kPa. Although it is possible to reduce the free resorcin content to some extent by this removal operation, when the free resorcin content in the reaction mixture before solvent removal is more than 12% by mass, the free resorcin content of the cocondensate after solvent removal is reduced. In order to make it 12% by mass or less, high temperature and high pressure reduction conditions that are difficult to implement industrially are necessary, and the cocondensate obtained at this time is colored by heat, thereby reducing the product value. is there.

[Preparation of Tire Rubber Composition]
The rubber composition for tires according to this embodiment is obtained by kneading the various components and additives described above using a kneader such as an open kneader such as a roll or a closed kneader such as a Banbury mixer. can get.
That is, the rubber composition for tires according to the present embodiment is a first step of kneading, and the addition of components other than the rubber component (A) and the cocondensate (C), and further insoluble sulfur (B) and a vulcanization accelerator. After kneading the agent, it can be produced by mixing insoluble sulfur (B) and a vulcanization accelerator at the final stage of kneading.
Further, by adding a part or all of the vulcanization accelerator in the stage before the final stage of kneading and kneading, the vulcanizing agent and the remaining vulcanization accelerator are mixed in the final stage of kneading. Can be produced. In this case, at least one compound selected from guanidines, sulfenamides and thiazoles can be used as the vulcanization accelerator to be added in the stage before the final stage of kneading.
Moreover, the rubber composition for tires according to this embodiment can contain at least one compound selected from thiourea and diethylthiourea. In this case, after adding and kneading at least one compound selected from thiourea and diethylthiourea in the stage before the final stage of kneading, the vulcanizing agent, the vulcanization accelerator and the rest are added in the final stage of kneading. Can be prepared by mixing thiourea and / or diethylthiourea.

[Production of pneumatic tires]
A tire is manufactured by a normal tire manufacturing method using the tire rubber composition according to the present embodiment. That is, the rubber composition for tires containing the various chemicals described above is processed into each member at an unvulcanized stage, and is pasted and molded by a normal method on a tire molding machine to form a raw tire. The green tire is heated and pressed in a vulcanizer to obtain a tire. In this way, a tire having good durability, particularly a pneumatic tire can be obtained.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.
[Method for evaluating cocondensate]
Analysis and physical property evaluation of the cocondensate were performed as follows.
(A) Measurement of average molecular weight of cocondensate The average molecular weight of the cocondensate was calculated as a polystyrene-converted weight average molecular weight by gel permeation chromatography (GPC) analyzed under the following apparatus and conditions.
-Equipment used: HLC-8220GPC (manufactured by Tosoh Corporation),
Column: TSK guard column SUPER HZ-L (manufactured by Tosoh Corporation)
+ TSK-GEL SUPER HZ1000 (4.6mmφ × 150mm)
+ TSK-GEL SUPER HZ2500 (4.6mmφ × 150mm)
+ TSK-GEL SUPER HZ4000 (4.6 mmφ × 150 mm),
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 cocondensate was dissolved in 20 mL of tetrahydrofuran.

(B) Measurement of residual monomer and residual solvent The residual monomer and residual solvent were quantified by gas chromatography based on 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
・ Vaporization chamber temperature: 250 ℃
-Detector temperature: 280 ° C
・ Detector: FID
・ Carrier: Nitrogen gas (40ml / min)
・ Combustion gas: Hydrogen (60 kPa), Air (60 kPa)
・ Injection volume: 2μL
About 0.5 g of the cocondensate and 0.05 g of anisole as an internal standard were dissolved in 10 mL of acetone and analyzed under the above conditions. Residual solvent and residual monomer contents (%) in the cocondensate were measured by an internal standard method (GC-IS method). In addition, content (%) described in the text of Examples and Comparative Examples is expressed as mass percent unless otherwise specified.

(C) Measurement of softening point It was measured by a method based on JIS-K2207-1996 (ring and ball method).
(D) Content ratio of each structural unit in co-condensation resin ¹ H-NMR analysis was performed by a method based on the following conditions.
・ Equipment: “JMN-ECS” (400 MHz) manufactured by JEOL Ltd.
Solvent: deuterium substituted dimethyl sulfoxide.
-Chemical shift of each component: Tetramethylsilane was used as a reference (0 ppm), and the peak indicated by the following values was defined as the peak of each component.
P-tert-Butylphenol-derived p-tert-butyl group proton: 1.0 to 1.2 ppm, formaldehyde-derived methylene group proton: 3.4 to 3.9 ppm, o-phenylphenol-derived o-phenyl Group proton: 7.1-7.5 ppm.
In addition, about the component ratio in a following example and a comparative example, it is a ratio based on the following references | standards.
o-Phenylphenol: Ratio when p-tert-butylphenol is 1 (mole times), methylene group derived from formaldehyde: Ratio to the total amount of o-phenylphenol and p-tert-butylphenol (mole times).

[Production of co-condensate]
<Production Example 1>
In a four-necked separable flask equipped with a reflux condenser and a thermometer, 97.3 g (1.2 mol) of formalin with a purity of 37%, 15.0 g (0.10 mol) of p-tert-butylphenol, 85 of o-phenylphenol 85 0.0 g (0.50 mol) and 75.4 g of toluene were sequentially added. Thereafter, the temperature was raised to an internal temperature of 45 ° C., 20 g (0.12 mol) of a 24% aqueous sodium hydroxide solution was added, and the mixture was stirred until the heat generation stopped. After confirming that the exotherm had subsided, the temperature was raised to an internal temperature of 65 ° C. and kept at that temperature for 2 hours. Thereafter, the temperature was raised again until the internal temperature reached 80 ° C., and the temperature was further kept for 4 hours.
After completion of the reaction, the reaction mixture was cooled to an internal temperature of 65 ° C. or less, neutralized by adding 49 g of water and 7.55 g (1.13 mol) of oxalic acid dihydrate, and 22.6 g of toluene was added, and then allowed to stand. And the aqueous layer was removed.
62.7 g (0.57 mol) of resorcin was added, the temperature was raised to an internal temperature of 70 ° C., and azeotropic dehydration was performed for 4 hours under reduced pressure. During this time, the internal temperature rose to 90 ° C. Subsequently, the temperature was raised to 115 ° C. at normal pressure, and azeotropic dehydration was performed for 1 hour. Thereafter, the temperature was raised to an internal temperature of 145 to 150 ° C., and the solvent toluene was distilled off by keeping the temperature for 2 hours. Thereafter, the pressure was reduced to 16 kPa while maintaining the internal temperature at 140 to 150 ° C., and the solvent toluene was further distilled off by maintaining the temperature for 2 hours. By the above operation, 177 g of orange cocondensate was obtained.
Average molecular weight of the cocondensate: 2160, softening point of the cocondensate: 123 ° C., residual toluene content in the cocondensate: 1.1%, residual p-tert-butylphenol content: 0.0%, residual o-phenyl Phenol content: 0.4%, Residual resorcin content: 9.5%. Ratio of each structural unit of the cocondensate: o-phenylphenol: 5.40, methylene group: 1.33.

[Rubber composition for tire containing co-condensate]
<Cocondensate obtained in Production Example 1>
An unvulcanized rubber composition was produced using resorcin resins 1 and 2 shown in Table 1 below as the resin adhesive. Resorcin resin 1 is a cocondensate produced in Production Example 1, and resorcin resin 2 is SUMIKANOL620 (manufactured by Taoka Chemical Industry Co., Ltd.), which is a commercially available conventional resin adhesive.

In Table 1, in the case of Production Example 1, free phenols represent the total amount of p-tert-butylphenol and o-phenylphenol. In the case of SUMIKANOL620, it represents the total amount of p-tert-octylphenol and p-cresol. The remaining amount in Table 1 represents the remaining amount (% by mass) of the solvent.

<Manufacture of unvulcanized rubber composition>
According to the formulation shown in Table 2, a mixture is prepared by mixing insoluble sulfur, components other than the vulcanization accelerator and methylene donor compound, and the resin adhesive shown in Table 1 with a pressure kneader made by Toshin, When it reached 160 ° C., it was discharged.
Subsequently, insoluble sulfur, a vulcanization accelerator, and a methylene donor were added to the obtained mixture with a 6-inch open roll made of Kansai Roll, which was kept at 60 ° C., and mixed to prepare a rubber composition for steel cord coating.

[Evaluation 1 of rubber composition for tire]
[Evaluation Method for Tire Rubber Composition Containing Cocondensate]
Using each of the unvulcanized rubber compositions obtained as described above, samples of vulcanized rubber and rubber-steel cord composites were prepared and evaluated as follows. A steel cord having a 1 × 3 × 0.3 mm structure and copper plating of copper / zinc = 63/37 (weight ratio) was used.
Wet heat adhesion and post-degradation crack resistance were evaluated by the following methods.

(A) Crack resistance after deterioration The unvulcanized sample was vulcanized at 160 ° C. for 20 minutes to prepare a vulcanized rubber sample having a thickness of 2 mm, and the sample was deteriorated at 100 ° C. for 24 hours. Then, the constant stress fatigue test of the first term sample was performed using the Ueshima made fatigue test machine, and the frequency | count until it fractured was measured. The results were expressed as an index with Comparative Example 1 as 100. It shows that it is excellent in the crack progress property after deterioration, so that an index value is large.
Crack resistance index = {(number of times until the test sample is cut) / (number of times until the sample of Comparative Example 1 is cut)} × 100

(B) Wet heat adhesion (adhesion after wet heat aging)
The metal cords were arranged in parallel at intervals of 12.5 mm, the metal cords were covered with the rubber composition from above and below, and vulcanized at 160 ° C. for 20 minutes to bond the rubber composition and the metal cord. In this way, a metal cord-rubber composite in which a metal cord was embedded between rubber sheets having a thickness of 1 mm was obtained (the metal cord was in the direction of the thickness center of the rubber sheet, parallel to the sheet surface, 12 .. arranged at intervals of 5 mm). After this metal cord-rubber composite was deteriorated for 10 days at 75 ° C. and 95% relative humidity, the metal cord was pulled out from each sample in accordance with ASTM D 2229, and the rubber adhered to the metal cord The coverage was determined by visual observation from 0 to 100%, and was used as an indicator of thermal degradation. The results were expressed as an index with Comparative Example 1 as 100. It shows that it is excellent in wet heat adhesiveness, so that an index value is large. That is, it shows that it is excellent in resistance to thermal degradation.
Wet heat adhesion index = {(Rubber coverage attached to metal cord of test sample) / (Rubber coverage attached to metal cord of sample of Comparative Example 1)} × 100
In this evaluation, the one with an increased index value for both crack growth resistance and wet heat adhesion evaluation was considered acceptable.

* 1 Natural rubber: SMR-CV60
* 2 Insoluble sulfur: “Cristex HS OT-20” manufactured by Flexis
* 3 Resorcin resin 1: Resorcin resin produced by Production Example 1 * 4 Resorcin resin 2: "Sumikanol 620" manufactured by Taoka Chemical Co., Ltd.
* 5 DCPD resin: dicyclopentadiene resin “Quinton 1105” manufactured by Nippon Zeon Co., Ltd.
* 6 Carbon Black: “Seast 300” (HAF-LS grade) manufactured by Tokai Carbon Co., Ltd.
* 7 Zinc oxide: 2 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd. * 8 Anti-aging agent: "NOCRACK 6C" manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 9 Vulcanization accelerator: N, N-dicyclohexyl-2-benzothiazolylsulfenamide (reagent)
* 10 Cobalt fatty acid salt: Cobalt stearate (reagent)
* 11 Methylene donor compound: Modified etherified methylol melamine resin "Sumikanol 507AP" manufactured by Taoka Chemical Co., Ltd.

[Evaluation results]
From Comparative Example 2 and Comparative Example 4, it can be seen that, when the amount of sulfur is reduced, the crack resistance after deterioration is improved, but the wet heat adhesiveness is lowered. On the other hand, according to Example 1-3, if resorcin resin 1 is blended, it is possible to improve post-degradation crack resistance without decreasing wet heat adhesion even if the amount of sulfur is reduced. I understand that I can do it. Furthermore, by blending the DCPD resin, it is possible to improve both the crack resistance after degradation and the wet heat adhesion.
However, although the resorcin resin 2 of Reference Example 1 can improve wet heat adhesion, crack resistance after degradation deteriorates. In addition, according to Comparative Example 6, even if it is resorcin resin 1, wet heat adhesiveness is reduced by excessively blending it. Therefore, by using resorcin resin 1 in a specific blending amount range, wet heat adhesiveness is reduced. It turns out that the effect to raise is acquired.
From the above, according to the present invention, by using a specific resorcin resin, the blending amount of insoluble sulfur is 1.0 parts by mass or more and 6.5 parts by mass or less with respect to 100 parts by mass of the rubber component (A). However, the post-degradation crack resistance can be improved without reducing wet heat adhesion.

[Evaluation 2 of tire rubber composition]
According to the formulation shown in Table 3, a mixture was prepared in the same manner as in Evaluation 1, and a rubber composition for coating a steel cord and an unvulcanized sample for a peel adhesion test were prepared. The obtained sample was evaluated by the following method.
(A) Wet heat adhesion (adhesion after wet heat aging)
The same method as the evaluation method shown in Table 2 was applied.
In this evaluation, the index value of the adhesive evaluation was determined to pass if the index value of the wet heat adhesive evaluation was improved as compared with Comparative Example 12 in which silica was not blended.

* 1 to * 11 are the same as Table 2.
* 12 Silica: “Nippil-AQ” manufactured by Tosoh Silica Corporation

[Evaluation results]
It was found that if the blending amount of the resorcin resin 1 and the blending amount of sulfur are within an appropriate amount range based on the results shown in Table 2, wet heat adhesion can be greatly improved by blending silica. Furthermore, it turned out that wet heat adhesiveness can be improved by making the compounding quantity of a silica into the range of 1 to 65 mass parts with respect to 100 mass parts of rubber components (A).

[Evaluation 3 of Tire Rubber Composition]
According to the formulation shown in Table 4, a mixture was prepared in the same manner as in Evaluation 1, and a rubber composition for coating a steel cord and an unvulcanized sample for a peel adhesion test were prepared. The obtained sample was evaluated by the following method.
(A) 100% elongation tensile stress (M100)
The unvulcanized sample was vulcanized at 160 ° C. for 20 minutes, and this sample was measured for 100% elongation tensile stress according to JIS K6251: 2010. The results were expressed as an index with Comparative Example 11 as 100. It shows that it is excellent in a growth 100% elongation tensile stress, so that an index value is large.
(B) Wet heat adhesion (adhesion after wet heat aging)
The same method as the evaluation method shown in Table 2 was applied.
In this evaluation, an index value increased in both 100% elongation tensile stress and wet heat adhesiveness was regarded as acceptable.

* 1 to * 12 are the same as Tables 2 and 3.
* 13 Bismaleimide compound: “BMI-1000” manufactured by Daiwa Kasei Kogyo Co., Ltd.

[Evaluation results]
If the blending amount of the resorcin resin 1 and the blending amount of sulfur are within an appropriate range based on the results of Table 2, 100% elongation tensile stress can be improved by blending the bismaleimide compound. Moreover, the fall of wet heat adhesiveness can be suppressed by mix | blending a silica. Furthermore, the reinforcement property of progress rubber | gum can be improved further by mix | blending DCPD resin.

[Evaluation 4 of rubber composition for tire]
According to the formulation shown in Table 5, a mixture was prepared in the same manner as in Evaluation 1, and a rubber composition for steel cord coating and an unvulcanized sample for a peel adhesion test were prepared. The obtained sample was evaluated by the following method.
(A) Crack growth resistance after deterioration The same method as the evaluation method shown in Table 2 was applied.
(B) Wet heat adhesion (adhesion after wet heat aging)
The same method as the evaluation method shown in Table 2 was applied.
In this evaluation, both the crack progress resistance after degradation and the wet heat adhesion were evaluated as having passed the index value.

* 1 to * 12 are the same as Table 1 and Table 2.

[Evaluation results]
If the amount of resorcin resin 1 and the amount of sulfur are within the appropriate ranges based on the results in Table 2, the amount of cobalt fatty acid salt is reduced to 0.01 to 0.08 parts by mass in terms of cobalt content. Even when it is made, crack progress resistance can be improved, without reducing wet heat adhesiveness. Moreover, wet heat adhesiveness and crack progress resistance can be further improved by mix | blending a silica.

[Evaluation 5 of Tire Rubber Composition]
In accordance with the formulation shown in Table 6, a mixture was prepared in the same manner as in Evaluation 1, and a rubber composition for coating a steel cord and an unvulcanized sample for a peel adhesion test were prepared. The obtained sample was evaluated by the following method.
(A) Wet heat adhesion (adhesion after wet heat aging)
The same method as the evaluation method shown in Table 2 was applied.
In this evaluation, Example 1 using the vulcanization accelerator DZ and resorcin resin was used as a reference, and the index value of wet heat adhesion increased was determined to be acceptable.

* 14 Vulcanization accelerator 1 CZ (N-cyclohexyl-2-benzothiazolylsulfenamide), manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller CZ”
* 15 Vulcanization accelerator 2 NS (N-ter-butyl-2-benzothiazylsulfenamide), manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller NS”
* 16 Vulcanization accelerator 3 TBSI (N-tert-butyl-2-benzothiazolylsulfenimide), manufactured by Flexis Co., Ltd., “Sant Cure TBSI”
* 17 Vulcanization accelerator 4 BEHZ (N, N-di (2-ethylhexyl) -2-benzothiazolylsulfenamide), manufactured by Kawaguchi Chemical Industry Co., Ltd., “BEHZ”
* 18 Vulcanization accelerator 5 DZ (N, N'-dicyclohexyl-2-benzothiazylsulfenamide), manufactured by Ouchi Shinsei Chemical Co., Ltd., "Noxeller DZ"

[Evaluation results]
If the blending amount of the resorcin resin 1 and the blending amount of sulfur are within appropriate ranges based on the results shown in Table 2, the vulcanization accelerator 5, that is, the vulcanization accelerator DZ (N, N′-dicyclohexyl-2-benzo It has been found that wet heat adhesion can be improved by using vulcanization accelerators 1 to 4 as compared to the case of using thiazylsulfenamide (including Example 1).

[Evaluation 6 of rubber composition for tire]
In accordance with the formulation shown in Table 6, a mixture was prepared in the same manner as in Evaluation 1, and a rubber composition for coating a steel cord and an unvulcanized sample for a peel adhesion test were prepared. The obtained sample was evaluated by the following method.
(A) Initial adhesiveness Steel cords are arranged in parallel at an interval of 12.5 mm, the steel cords are covered with a rubber composition from above and below, and vulcanized at 160 ° C. for 7 minutes, whereby the rubber composition and the steel cord are Glued. In this way, a rubber-metal composite in which a steel cord was embedded in a rubber sheet having a thickness of 1 mm was obtained (the steel cord was placed at the center of the rubber sheet in the thickness direction and at an interval of 12.5 mm on the sheet surface. Are lined up). Thereafter, in accordance with ASTM D 2229, the steel cord was pulled out from each sample immediately after vulcanization, and the coverage of the rubber adhering to the steel cord was determined by visual observation from 0 to 100%. It was used as an index. The results were expressed as an index with Comparative Example 1 as 100. It shows that it is excellent in initial stage adhesiveness, so that an index value is large.
Initial adhesiveness index = {(Rubber coverage adhered to metal cord of test sample) / (Rubber coverage adhered to metal cord of Comparative Example 1)} × 100
(B) Wet heat adhesion (adhesion after wet heat aging)
The same method as the evaluation method shown in Table 2 was applied.
In this evaluation, the comparative example 72 containing no resorcin resin was used as a reference, and the index values of the initial adhesiveness and wet heat adhesiveness both increased.

* 19 Rust inhibitor 1 1,2,3-triazole (reagent)
* 20 Antirust agent 2 1,2,4-triazole (reagent)
* 21 Rust inhibitor 3 3-amino-1,2,4-triazole (reagent)
* 22 Rust inhibitor 4 4-amino-1,2,4-triazole (reagent)
* 23 Rust inhibitor 5 Imidazole (reagent)

[Evaluation results]
If the blending amount of resorcin resin 1 and the blending amount of sulfur are within the appropriate ranges based on the results shown in Table 2, the wet heat adhesion is further improved by blending a specific triazole compound or imidazole compound as a rust inhibitor. Can be made. Moreover, wet heat adhesiveness can be improved further by mix | blending a silica.

In addition, as a result of the evaluations 1 to 6 of the tire rubber compositions shown in Tables 2 to 7 described above, unreacted monomers other than free resorcin contained in the tire rubber composition according to the present invention and The total amount of the residual solvent is 0.03% by mass with respect to the rubber component, which is significantly less than 0.17% by mass, and is contained in the rubber composition containing the conventional product (SUMIKANOL620) according to Reference Example 1. Compared with 0.246% by mass of the total amount of unreacted monomers and residual solvent other than resorcin, the generation of odors during kneading of the unvulcanized rubber composition is greatly reduced, and capital investment for work environment conservation is reduced. It was greatly reduced.

The rubber composition for tires according to the present invention is suitable for use in a composite of a metal article and rubber, such as a rubber article, in particular, a tire carcass or a reinforcing material for a belt. In particular, when the rubber composition for tires according to the present invention is applied to a metal cord-rubber composite used for a belt or the like of a tire for trucks and buses, a tire for passenger cars, especially a radial tire for passenger cars, Adhesion can be improved.

Claims

Rubber component (A), insoluble sulfur (B), structural unit derived from p-tert-butylphenol represented by the following formula (1), structural unit derived from o-phenylphenol represented by the following formula (2) And a co-condensate (C) containing a structural unit derived from resorcin represented by the following formula (3) and having a softening point of 150 ° C. or lower,
The amount of the insoluble sulfur (B) is 1.0 part by mass or more and 6.5 parts by mass or less with respect to 100 parts by mass of the rubber component (A), and the amount of the cocondensate (C) is The rubber composition for tires which is 0.1 mass part or more and 10 mass parts or less with respect to 100 mass parts of rubber components (A).
The tire rubber composition according to claim 1, wherein the amount of the insoluble sulfur (B) is 2 parts by mass or more and 6.5 parts by mass or less.
The rubber for tire according to claim 1 or 2, comprising a filler, wherein a total amount of the filler is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component (A). Composition.
The rubber for tire according to claim 1 or 2, comprising a filler, wherein a total amount of the filler is 20 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component (A). Composition.
The tire rubber according to claim 3 or 4, wherein the filler contains silica, and the amount of the silica is 1 part by mass or more and 65 parts by mass or less with respect to 100 parts by mass of the rubber component (A). Composition.
The rubber for tire according to claim 3 or 4, wherein the filler contains silica, and the amount of the silica is 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the rubber component (A). Composition.
2. An organic cobalt compound is blended, and the blending amount of the organic cobalt compound is 0.01 parts by mass or more and 0.08 parts by mass or less in terms of cobalt content with respect to 100 parts by mass of the rubber component (A). 7. The tire rubber composition according to any one of 1 to 6.
2. An organic cobalt compound is blended, and the blending amount of the organic cobalt compound is 0.02 parts by mass or more and 0.07 parts by mass or less in terms of cobalt content with respect to 100 parts by mass of the rubber component (A). 7. The tire rubber composition according to any one of 1 to 6.
The bismaleimide compound is blended, and the blending amount of the bismaleimide compound is 0.1 parts by mass or more and 5.5 parts by mass or less with respect to 100 parts by mass of the rubber component (A). The rubber composition for tires according to claim 1.
The bismaleimide compound is blended, and the blending amount of the bismaleimide compound is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component (A). The rubber composition for tires according to item.
A vulcanization accelerator is blended, and the vulcanization accelerator is N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazylsulfenamide, N-tert-butyl- And at least one selected from 2-benzothiazolylsulfenimide and N, N-di (2-ethylhexyl) -2-benzothiazolylsulfenamide, and the compounding amount of the vulcanization accelerator is a rubber component (A) The rubber composition for tire according to any one of claims 1 to 10, wherein the rubber composition is 0.5 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass.
A rust preventive agent is blended, and the rust preventive agent includes a nitrogen-containing cyclic compound having a structure in which at least one carbon atom of the cyclic compound having 5 or less carbon atoms is substituted with a nitrogen atom, and the rust preventive agent The rubber composition for a tire according to any one of claims 1 to 11, wherein a blending amount of the rubber component is 0.02 parts by mass or more and 12 parts by mass or less with respect to 100 parts by mass of the rubber component (A).
The rubber composition for tire according to any one of claims 1 to 12, wherein the softening point of the co-condensate (C) is 80 ° C or higher and 150 ° C or lower.
The rubber composition for tires according to any one of claims 1 to 12, wherein the softening point of the cocondensate (C) is 80 ° C or higher and 140 ° C or lower.