JP2000336213A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition, which is improved in physical properties such as strength, hardness and the like by compounding an epoxy resin and a vulcanizer to rubber without compounding an alkylphenol formaldehyde resin,. SOLUTION: A butadiene rubber is preferred as a rubber, and a styrene/ butadiene rubber or butadiene rubber is more preferred. The epoxy resin may be either liquid or solid, and should usually have an epoxy equivalent of 200 or below. The epoxy resin is generally compounded in an amount of 0.5 to 100 pts.wt. per 100 pts.wt. of the rubber. The vulcanizer is generally compounded in an amount of 0.2 to 5 pts.wt. per 100 pts.wt. of the rubber. Moreover, a filler may be added. The amount of the filler ranges from 30 to 200 pts.wt. per 100 pts.wt. of the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition, and more particularly, to a rubber composition having improved physical properties such as strength and hardness without deteriorating workability in a rubber kneading operation or the like. About.

[0002]

2. Description of the Related Art Styrene / butadiene rubber and butadiene rubber are used for rubber tires of footwear such as automobile or bicycle tires, shoes, campus shoes, injection molded articles, belts, rolls such as hulling rolls, hoses, electric wires and cables. It is used in large quantities in a wide range of fields. These rubbers are sometimes used as pure rubber vulcanizates, but usually have many applications that require mechanical resistance, so they are filled with carbon black, talc, calcium carbonate, clay, etc. that have an appropriate reinforcing effect. Products with enhanced physical properties such as tensile strength, rupture strength and hardness by blending an agent (reinforcing agent) are provided as products. However, for example, it is common to increase the amount of filler added as a means to improve the tensile strength or hardness, but in this case, the viscosity of the rubber compound becomes high, so that the filler becomes difficult to be uniformly dispersed. In the normal kneading time, the filler is confirmed as a small white solid on the cross section of the kneaded rubber compound. Therefore, it is necessary to knead the rubber composition for a long time to obtain a uniformly dispersed rubber composition, but as a result, the productivity is reduced. Therefore, there is a limit in increasing the hardness by increasing the amount of filler added, and furthermore, there is a problem that physical properties such as tensile strength due to the increased amount of filler do not improve as expected. Was.

[0003]

There is a need for a rubber composition having improved physical properties, such as strength and hardness, without lowering the productivity in a rubber kneading operation or the like.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a rubber composition which simultaneously satisfies the above problems can be obtained. That is, the present invention provides (1) a rubber composition containing a rubber, an epoxy resin and a vulcanizing agent and not containing an alkylphenol-formaldehyde resin; (2) a rubber composition according to (1), wherein the rubber is a butadiene rubber; ) The rubber composition of (2), wherein the butadiene rubber is styrene-butadiene rubber or butadiene rubber; (4) an epoxy resin is contained in an amount of 0.5 to 100 parts by weight based on 100 parts by weight of the rubber. The rubber composition according to any one of the above,
(5) The rubber composition according to any one of (1) to (4), wherein the epoxy resin is a novolak epoxy resin, a cresol novolak epoxy resin, a bisphenol A epoxy resin, or a bisphenol F epoxy resin.
(6) The rubber composition according to any one of (1) to (5), wherein the epoxy equivalent of the epoxy resin is 500 or less,
(7) The rubber composition according to any one of (1) to (6), wherein the rubber composition contains 30 to 200 parts by weight of a filler with respect to 100 parts by weight of rubber, and (8) any of (1) to (7). Or a molded rubber article of the rubber composition according to item 1.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The rubber used in the present invention includes, for example, styrene-butadiene rubber, butadiene rubber, natural rubber, nitrile-butadiene rubber, chloroprene rubber, isoprene rubber, isoprene-isobutylene rubber (IIR) butylated rubber, Ethylene-propylene terpolymer, chlorsulfonated polyethylene, chlorinated polyethylene, chlorinated butyl rubber, acrylic rubber, olefin rubber, fluorine rubber, silicon rubber, polysulfide rubber, urethane rubber, propylene oxide rubber, epichlorohydrin / ethylene oxide copolymer, Commercially available rubbers such as epichlorohydrin rubber can be mentioned, but styrene / butadiene rubber, butadiene rubber, natural rubber, nitrile / butadiene rubber, chloroprene rubber, isoprene rubber are preferred. Butyl rubber, ethylene
Propylene terpolymer, more preferably styrene-butadiene rubber, butadiene rubber, natural rubber, nitrile-butadiene rubber, chloroprene rubber, isoprene rubber, even more preferably styrene-butadiene rubber, butadiene rubber, nitrile-butadiene rubber, etc. Butadiene rubber having butadiene as a polymerization component,
Particularly, styrene-butadiene rubber and butadiene rubber are used. These rubbers can be used alone or as a mixture of two or more.

Examples of the epoxy resin used in the present invention include a polyfunctional epoxy resin which is a glycidyl etherified product of a polyphenol compound, a polyfunctional epoxy resin which is a glycidyl etherified product of various novolak resins, an alicyclic epoxy resin, and a heterocyclic epoxy resin. Epoxy resins, glycidyl ester epoxy resins, glycidylamine epoxy resins, and epoxy resins obtained by glycidylation of halogenated phenols are exemplified.

Examples of polyfunctional epoxy resins which are glycidyl etherified compounds of polyphenols include bisphenol A, bisphenol F, bisphenol S, 4,4'-biphenylphenol, tetramethylbisphenol A, dimethylbisphenol A, and tetramethylbisphenol F. , Dimethylbisphenol F, tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4'-biphenol, dimethyl-4,4'-biphenylphenol, 1- (4-hydroxyphenyl) -2- [4- (1 , 1-bis- (4-hydroxyphenyl) ethyl) phenyl] propane, 2,
2′-methylene-bis (4-methyl-6-tert-butylphenol), 4,4′-butylidene-bis (3-
Methyl-6-tert-butylphenol), trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, phenols having a diisopropylidene skeleton, phenols having a fluorene skeleton such as 1,1-di-4-hydroxyphenylfluorene, phenol And polyfunctional epoxy resins which are glycidyl etherified products of polyphenol compounds such as polybutadiene.

Examples of polyfunctional epoxy resins which are glycidyl etherified products of various novolak resins include, for example, phenol, cresols, ethylphenols, butylphenols, octylphenols, bisphenol A,
Novolak resins, phenol novolak resins containing a xylylene skeleton, phenol novolak resins containing a dicyclopentadiene skeleton, phenol novolak resins containing a biphenyl skeleton, phenol novolak resins containing a fluorene skeleton, etc. made from various phenols such as bisphenol F, bisphenol S, and naphthols. Examples include glycidyl etherified products of various novolak resins.

Examples of the alicyclic epoxy resin include an alicyclic epoxy resin having an aliphatic skeleton such as cyclohexane. Examples of the aliphatic epoxy resin include 1,4-butanediol and 1,6-hexane. Diol,
Examples include glycidyl ethers of polyhydric alcohols such as polyethylene glycol and pentaerythritol. Examples of the heterocyclic epoxy resin include a heterocyclic epoxy resin having a heterocyclic ring such as an isocyanuric ring and a hydantoin ring, and a glycidyl ester-based resin. Examples of the epoxy resin include an epoxy resin comprising a carboxylic acid such as hexahydrophthalic acid diglycidyl ester.

Examples of the glycidylamine-based epoxy resin include an epoxy resin obtained by glycidylation of amines such as aniline and toluidine, and an epoxy resin obtained by glycidylation of halogenated phenols includes:
For example, epoxy resins obtained by glycidylation of halogenated phenols such as brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, brominated phenol novolak, brominated cresol novolak, chlorinated bisphenol S, and chlorinated bisphenol A are exemplified. .

Among these epoxy resins, bisphenol A, bisphenol F, bisphenol S, tetramethyl-4,4'-biphenol, 1- (4-hydroxyphenyl) -2- [4- (1,1-bis- ( 4-Hydroxyphenyl) ethyl) phenyl] propane, resorcinol, glycidyl etherified product of 1,1-di-4-hydroxyphenylfluorene, phenol, cresols, bisphenol A, bisphenol F, bisphenol S, novolak made from naphthols Glycidyl etherified products such as resins, phenol novolak resins having a xylylene skeleton, phenol novolak resins having a dicyclopentadiene skeleton, phenol novolak resins having a biphenyl skeleton, and phenol novolak resins having a fluorene skeleton; Alicyclic epoxy resin having a xanth ring, 1,6-hexanediol, glycidyl ethers of polyethylene glycol, triglycidyl isocyanurate, diglycidyl hexahydrophthalate,
Diglycidyl tetrahydrophthalate, N, N-
Glycidylated products of diglycidylaniline, N, N-diglycidyltoluidine, brominated bisphenol A, brominated phenol novolak, and brominated cresol novolak are preferred.

More preferably, bisphenol A, bisphenol F, tetramethyl-4,4'-biphenol,
1- (4-hydroxyphenyl) -2- [4- (1,1
-Bis- (4-hydroxyphenyl) ethyl) phenyl] propane, resorcinol, glycidyl etherified product of 1,1-di-4-hydroxyphenylfluorene,
Glycidyl etherified phenolic novolak resin containing phenol, cresols, bisphenol A, naphthols, phenol novolak resin containing xylylene skeleton, phenol novolak resin containing dicyclopentadiene skeleton, phenol novolak resin containing biphenyl skeleton, and phenol novolak resin containing fluorene skeleton Alicyclic epoxy resin having a cyclohexane ring, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, N, N-diglycidylaniline, N, N-diglycidyltoluidine, brominated bisphenol A, brominated phenol It is a glycidylated product of novolak.

Particularly preferred are bisphenol A, bisphenol F, tetramethyl-4,4'-biphenol, resorcinol, glycidyl etherified 1,1-di-4-hydroxyphenylfluorene, phenol, cresols, bisphenol A, and naphthol. Resins, phenol novolak resins containing a xylylene skeleton, phenol novolak resins containing a dicyclopentadiene skeleton, glycidylated phenol novolak resins containing a biphenyl skeleton, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, N , N-diglycidylaniline,
An epoxy resin such as N, N-diglycidyl toluidine. Further, these epoxy resins can be used alone or as a mixture of two or more as required.

The epoxy resin used in the present invention is a liquid,
It is used in any solid form and has an epoxy equivalent of 200
0 or less, preferably 1000 or less, more preferably 800 or less, particularly preferably 500 or less. 20
If it is more than 00, it will not be uniformly dispersed in the rubber at the time of kneading, and the improvement in characteristics will be small. The amount of the epoxy resin used is 0.5 to 100 parts by weight, preferably 0.5 to 80 parts by weight, and more preferably 1 to 100 parts by weight based on 100 parts by weight of rubber.
The amount is from 50 to 50 parts by weight, particularly preferably from 1 to 40 parts by weight. At 0.5 parts by weight or less, no improvement in physical properties is observed as compared with the case where no additive is added, and at 100 parts by weight or more, no further improvement in physical properties is observed as compared with the case of not more than 100 parts by weight.

[0015] The rubber composition of the present invention does not contain an alkylphenol-formaldehyde resin. Examples of the alkylphenol-formaldehyde resin include, for example, tackyl 201 (manufactured by Taoka Chemical Co., Ltd.) and Hitanol 250.
1 (manufactured by Hitachi Chemical Co., Ltd.), SP1044, SP1045
(Schenectady International, Inc., USA).

[0016] A filler may be added to the rubber composition of the present invention. As the filler, for example, channel black,
Various types of carbon black such as furnace black, calcium carbonate, talc, clay (kaolinite), calcined clay (kaolinite), magnesium oxide, zinc oxide, cyclic white carbon, fine white silica such as wet white carbon, etc. Silicates such as aluminum silicate, lithium aluminum silicate and zirconium silicate, fused silica, crystalline silica, bentonite, magnesium carbonate, barium sulfate, calcium sulfate, mica, alumina, silicon carbide, silicon nitride, boron nitride, zirconium oxide, aluminum hydroxide , Magnesium hydroxide, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos and the like.

Preferably, various carbon blacks such as channel black and furnace black, calcium carbonate, talc, clay (kaolinite), calcined clay (kaolinite), magnesium oxide, zinc oxide, cyclic white carbon, wet white carbon Fine particles such as silicate, calcium silicate, silicate such as aluminum silicate, fused silica, crystalline silica, bentonite, magnesium carbonate, barium sulfate, calcium sulfate, mica, alumina, aluminum hydroxide, magnesium hydroxide, glass fiber, carbon fiber Yes, more preferably various carbon blacks such as channel black and furnace black, calcium carbonate, talc, clay (kaolinite), calcined clay (kaolinite), magnesium oxide, zinc oxide, cyclic white powder Bonn, fine silicate, calcium silicate, such as wet process white carbon, silicates such as aluminum silicate, fused silica, crystalline silica, bentonite, and magnesium carbonate, particularly preferably channel black, various carbon blacks such as furnace black,
Fine particles such as calcium carbonate, talc, clay (kaolinite), calcined clay (kaolinite), magnesium oxide, zinc oxide, cyclic white carbon, wet white carbon, etc., and silicates such as calcium silicate and aluminum silicate. .

The amount of the filler used in the present invention is 30 to 200 parts by weight, preferably 40 to 170 parts by weight, more preferably 50 to 150 parts by weight per 100 parts by weight of rubber.
Parts by weight, particularly preferably 60 to 150 parts by weight. 3
When the amount is less than 0 parts by weight, no improvement in physical properties is obtained compared to the case of pure rubber, and when the amount is more than 200 parts by weight, dispersion of the filler in the kneading process does not sufficiently proceed.

In the present invention, a filler surface-treated with a coupling agent or the like can also be used. Examples of the coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxy Silane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane , Vinyltrimethoxysilane, N- (2- (vinylbenzylamino) ethyl) 3-aminopropyltrimethoxysilane hydrochloride,
Silane coupling agents such as methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, isopropyl (N-ethylaminoethylamino) titanate, isopropyl triisostearoyl titanate, titanium Di (dioctyl pyrophosphate) oxyacetate, tetraisopropyl di (dioctyl phosphite) titanate, neoalkoxy tri (p-N
A titanium-based coupling agent such as-(β-aminoethyl) aminophenyl) titanate, Zr-acetylacetonate, Zr-methacrylate, Zr-propionate, neoalkoxyzirconate, neoalkoxytris neodecanoylzirconate, neoalkoxytris (Dodecanoyl) benzenesulfonyl zirconate, neoalkoxytris (ethylenediaminoethyl) zirconate, neoalkoxytris (m-aminophenyl) zirconate, ammonium zirconium carbonate, Al
-Acetylacetonate, Al-methacrylate, Al
A zirconium such as propionate, or an aluminum-based coupling agent, but preferably a silicon-based coupling agent. By using a coupling agent, a rubber vulcanizate having excellent properties can be obtained.

As the vulcanizing agent used in the present invention, a commercially available vulcanizing agent can be used, for example, sulfur, 4,4 '.
-Sulfur compounds such as -dithiodimorpholine, benzoyl peroxide, dicumyl peroxide, peroxides such as 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, tetrachloro-p-benzoquinone ,
quinone-based compounds such as p, p'-dibenzoylquinonedioxime and p-quinonedioxime; phosphonium salts represented by benzyltriphenylphosphonium chloride; hexamethylenetetramine carbamate;
N′-dicinnamylidene-1,6-hexanediamine,
Examples include amine compounds such as alicyclic amine salts, hexamethylenediamine carbamate, N, N'-m-phenylenediamine, and reaction products of nitrosophenol and diisocyanate. These vulcanizing agents are appropriately selected and used depending on the application and the type of rubber. The amount of rubber used is 10
0.2 to 5 parts by weight, preferably 0.3 to 0 parts by weight
To 4 parts by weight, more preferably 0.5 to 3 parts by weight.

In the rubber composition of the present invention, a vulcanization accelerator, an auxiliary vulcanization accelerator, an anti-scorch agent, an antioxidant,
Antioxidants, plasticizers, foaming agents, lubricants, processing aids and the like are used. Examples of the vulcanization accelerator include condensates of N-butyraldehyde and aniline, o-tolylbiguanidide, dibutylthiourea, diphenylguanidine, p, p'-
Dibenzoylquinone dioxime, dibenzothiazyl disulfide, di-o-tolylguanidine, tricrotonylidenetetramine, hexamethylenetetramine, acetaldehydeaniline condensate, cyclohexylamine, p,
Amines such as p'-diaminodiphenylmethane, diethylbenzothiazylsulfenamide, dibenzyldithiocarbamate, zinc dibutyldithiocarbamate, complex salt of dibenzothiazyldisulfide-zinc chloride, cadmium diethyldithiocarbamate, dibutylxanthogen disulfide, dithiocarbamate, N , N-Dicyclohexylbenzothiazyl-2-sulfenamide, N, N
-Diethylthiocarbamoyl-2-benzothiazyl sulfide, N, N-diethylthiourea, diethyldithiocarbamate, 2-mercaptobenzothiazolecyclohexylamine salt, tetramethylthiourea, 2-mercaptobenzothiazole, 2- (4′-morpholino Dithio) benzothiazole, N-oxydiethylenebenzothiazolesulfenamide, tert-butylbenzothiazolesulfenamide, N-oxydiethylenethiocarbamyl-N′-cyclopentamethylenesulfenamide, N-oxydiethylenethiocarbamyl- N'-
Oxydiethylene sulfenamide, pipecoline methylene pentamethylene dithiocarbamate, di-o-tolylguanidine dicatechol borate, piperidinium piperidine carbodithioate, zinc ethylphenyldithiocarbamate, zinc dimethyldithiocarbamate, N,
N-diethylthiocarbamoyl-2-benzothiazyl sulfide, sodium diethyl isopropylxanthenate diethyldithiocarbamate, tetrabutylthiuram disulfide, thiocarbamylsulfenamide, terium diethyldithiocarbamate, tetraethylthiuram disulfide, dimethylethylthiourea, trimethylthiourea, dithio Sulfur compounds such as sodium dithiocarbamate, dipentamethylenethiuram tetrasulfide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, copper dimethyldithiocarbamate, iron dimethyldithiocarbamate, thiourea, zinc dibenzyldithiocarbamate, zinc isopropylxanthenate are used. Can be

Examples of the vulcanization accelerator include commonly used vulcanization accelerators such as activated calcium hydroxide, diallyl isocyanurate, diallyl phthalate, ethylene glycol dimethacrylate and triallyl isocyanurate.

Examples of the scorch inhibitor include commonly used scorch inhibitors such as N-isopropylthio-N-cyclohexylbenzothiazolesulfonamide and phthalic anhydride.

Examples of antioxidants and antioxidants include octylated diphenylamine, acetone diphenylamine condensate, 2,6-di-tert-butyl-p-cresol, phenyl-β-naphthylamine, N- (1,3-
Dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,6-ditert-butyl-4-methylphenol, N, N'-di-2-naphthyldiphenylenediamine, 2,2,4-trimethyl- 1,2-dihydroquinoline polymer, N, N'-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-
Phenylenediamine, 2-mercaptobenzimidazole and its zinc salt, nickel dibutyldithiodicarbamate, 2,5-ditert-butylhydroquinone,
2,2'-methylene-bis- (4-methyl-6-ter
Antioxidants and antioxidants used in ordinary rubbers such as t-butylphenol) and styrenated phenol.

Examples of the plasticizer include plasticizers commonly used such as dioctyl adipic acid, dioctyl phthalic acid, dioctyl sebacic acid, tricresyl phosphate, liquid paraffin, and paraffin-based process oil. As the foaming agent, for example, urea derivatives such as N, N'-dinitrosopentamethylenetetramine, hydrazine derivatives such as toluenesulfonyl hydrazide, p, p-oxybis (benzenesulfonyl hydrazide) and the like are used. Commercially available lubricants such as carnauba wax, polyethylene wax, and stearamide are used as the lubricant. In addition, a tackifier, a coupling material, a curing agent used for curing an epoxy resin, and the like can be added.

To prepare the rubber composition of the present invention, a rubber other than butyl rubber, an epoxy resin, and a vulcanizing agent may be added, if necessary, to a filler, a vulcanization accelerator, a vulcanization accelerator, a scorch inhibitor, an aging agent. One-stage method in which an inhibitor, a plasticizer, a foaming agent, etc. are added and kneaded with an internal mixer, and a masterbatch (A kneaded product) in which components excluding a vulcanizing agent, a vulcanization accelerator and an epoxy resin are kneaded in advance. ), A vulcanizing agent, a vulcanization accelerator, and an epoxy resin are added thereto, and the mixture is kneaded again to obtain the rubber composition (B-kneaded product) of the present invention. The kneading temperature is 130 ° C. or lower, preferably 100 ° C. or lower, and more preferably 80 ° C. or lower. If the temperature is 130 ° C. or higher, crosslinking is undesirably initiated particularly when the one-step method is employed. The kneading time is 60 minutes or less, preferably 40 minutes or less, and more preferably 20 minutes or less, and the shorter the better. Internal mixers used for kneading include an intensive mixer (manufactured by Nippon Roll Co., Ltd.), a Mistron BB series (manufactured by Kobe Steel), a GK series mixer (manufactured by Mitsubishi Kogyo), a heavy banbury (manufactured by Sato Manufacturing), an intermix (manufactured by Hitachi) Examples thereof include hermetic kneaders generally used in the rubber industry such as kneaders (manufactured by mechanical engineering) and kneaders (such as Kurimoto Tekko) with high kneading work efficiency, and rolls such as two rolls.

The molded product of the present invention is prepared, for example, by putting the above kneaded rubber composition into a mold, at 130 to 200 ° C., preferably 140 to 180 ° C. for 10 to 120 minutes, preferably 2 minutes.
It is obtained by heating for 0 to 90 minutes. The molded product of the present invention thus obtained is excellent in physical properties such as tensile strength and hardness, and rubber soles for footwear such as automobile or bicycle tires, shoes, campus shoes, injection molded products, belts,
It can be used in wide fields such as rolls such as hulling rolls, hoses, electric wires and cables.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” means parts by weight. Reference Example 1 Styrene-butadiene rubber (SBR15 made by Nippon Synthetic Rubber)
02) 100 parts by weight, SRF carbon black (Asahi # 2)
0) 30 parts by weight, 80 parts by weight of hard clay, 20 parts by weight of paraffinic process oil, diethylene glycol 3
Parts by weight, 5 parts by weight of zinc oxide (zinc white # 3), and 1 part by weight of zinc stearate at 100 ° C. using a Banbury mixer.
The mixture was kneaded for 20 minutes to obtain A kneaded rubber I.

Reference Example 2 50 parts by weight of butadiene rubber (BR01 made by Nippon Synthetic Rubber) and styrene-butadiene rubber (SBR made by Nippon Synthetic Rubber)
1502) 50 parts by weight, SRF carbon black (Asahi #
20) 50 parts by weight of HAF carbon black (Asahi # 7)
0) 30 parts by weight, 50 parts by weight of hard clay, 30 parts by weight of paraffin-based process oil, 2 parts by weight of ethylene glycol, 5 parts by weight of zinc oxide (zinc white # 3), and 1 part by weight of zinc stearate using a Banbury mixer The mixture was kneaded at 100 ° C. for 20 minutes to obtain A-kneaded rubber II.

Example 1 A: 239 parts by weight of kneaded rubber A, 1 part by weight of cresol novolak type epoxy resin (EOCN104S, manufactured by Nippon Kayaku)
2 parts by weight of sulfur, dibenzothiazyl disulfide (DM)
1.2 parts by weight and 0.2 parts by weight of tetramethylthiuram monosulfide (TS) were kneaded at 80 ° C. using a two-roll mill to obtain a rubber composition of the present invention. At this time, there was no problem that the flow of the rubber compound was poor or kneading was difficult as compared with the case where no epoxy resin was added, and the workability was excellent. 100 * 300 * 1 of the rubber composition thus obtained
mm and heated at 150 ° C. for 1 hour for vulcanization to obtain a sheet-like vulcanized rubber composition of the present invention. Using this sheet, the hardness at Shore A was measured, and a 10 * 100 * 1 mm test piece was measured in accordance with JIS standards, and the tensile strength was measured using a Tensilon tester (manufactured by Toyo Baldwin). The stress was measured. The unit is Kg / mm ² . Table 1 shows the results. The higher the hardness Shore A and the midpoint stress, the better.
The workability was determined as follows. ：: The rubber flow is good when the rubber is kneaded, the kneading is easy, and the kneaded product can be easily formed into a sheet. ×: The rubber is hard when the rubber is kneaded, the flow of the rubber becomes poor, and the kneading requires time and power. Also, it is difficult to make the kneaded product into a sheet.

Examples 2 to 7 Kneading and vulcanization were performed in the same manner as in Example 1 except that the type and amount of the epoxy resin were changed as shown in Table 1, and the sheet-shaped vulcanized rubber of the present invention was used. A composition was obtained. Using this, the hardness and tensile strength of Shore A were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 A: 239 parts by weight of kneaded rubber I, 2 parts by weight of sulfur, 1.2 parts by weight of dibenzothiazyl disulfide (DM), and 0.2 parts by weight of tetramethylthiuram monosulfide (TS) were used using two rolls. And kneaded at 80 ° C. to obtain a rubber composition for comparison. The rubber composition thus obtained was used as a vulcanized comparative rubber composition in the form of a sheet in the same manner as in Example 1. Using this sheet, the hardness and tensile strength at Shore A were measured in the same manner as in Example 1. . Table 1 shows the results.

Comparative Example 2 A: 239 parts by weight of kneaded rubber I, 2 parts by weight of sulfur, 30 parts by weight of hard clay, dibenzothiazyl disulfide (DM)
1.2 parts by weight and 0.2 parts by weight of tetramethylthiuram monosulfide (TS) were kneaded at 80 ° C. using a two-roll mill to obtain a rubber composition for comparison. The rubber composition thus obtained was used as a vulcanized comparative rubber composition in the form of a sheet in the same manner as in Example 1. Using this sheet, the hardness and tensile strength at Shore A were measured in the same manner as in Example 1. . Table 1 shows the results.

Example 8 A 268 parts by weight of kneaded rubber A, cresol novolak type epoxy resin (EOCN104S manufactured by Nippon Kayaku), 2.3 parts by weight of sulfur, 2-mercaptobenzothiazole (M)
0.5 parts by weight, dibenzothiazyl disulfide (DM)
One part by weight and 0.8 part by weight of diphenylguanidine (D) were kneaded at 80 ° C. using a two-roll mill to obtain a rubber composition of the present invention. At this time, there was no problem that the flow of the rubber compound was poor or kneading was difficult as compared with the case where no epoxy resin was added, and the workability was excellent. The rubber composition thus obtained was made into a sheet-like vulcanized rubber composition in the same manner as in Example 1, and the hardness and tensile strength at Shore A were measured. Table 1 shows the results.

Comparative Example 3 A 268 parts by weight of kneaded rubber II, 2.3 parts by weight of sulfur, 2-
A rubber composition for comparison was prepared by kneading 0.5 parts by weight of mercaptobenzothiazole (M), 1 part by weight of dibenzothiazyl disulfide (DM), and 0.8 parts by weight of diphenylguanidine (D) at 80 ° C. using a two-roll mill. I got something. The rubber composition thus obtained was used as a vulcanized comparative rubber composition in the form of a sheet in the same manner as in Example 1, and the hardness and tensile strength at Shore A were measured. Table 1 shows the results.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 4 Example 5 Example 6 A-rubber I 239 239 239 239 239 239 239 A-rubber II Epoxy resin 1 1 2 5 10 20 Epoxy resin 2 2 Epoxy Resin 3 Sulfur 2 2 2 2 2 2 DM 1.2 1.2 1.2 1.2 1.2 1.2 TS 0.2 0.2 0.2 0.2 0.2 0.2 MD Hard clay ----------------------------- −−−−−−−−−−−−−− Shore A 60 64 69 73 77 64 Intermediate stress 0.310 0.368 0.469 0.493 0.517 0.377 Workability ○ ○ ○ ○ ○ ○

Table 1 (continued) Example 7 Example 8 Comparative Example 1 Comparative Example 2 Comparative Example 3 A kneaded rubber I 239 239 239 A kneaded rubber II 268 268 Epoxy resin 15 Epoxy resin 2 Epoxy resin 32 Sulfur 2 2.3 2 2 2.3 DM 1.2 1 1.2 1.2 1 TS 0.2 0.2 0.2 M 0.5 0.5 D 0.8 0.8 Hard clay 30 --- --------------------- −−−− Shore A 67 75 55 60 68 Intermediate stress 0.313 0.664 0.288 0.303 0.911 Workability ○ ○ ○ × ○

In the table, the components other than the A-rubbers I and II, sulfur and hard clay are as follows. Epoxy resin 1: Cresol novolak type epoxy resin (Nippon Kayaku EOCN104S) Epoxy resin 2: phenol novolak type epoxy resin (Nippon Kayaku EPPN501) Epoxy resin 3: Bisphenol A type epoxy resin (Epomic 828 from Yuka Shell) DM : Dibenzothiazyl disulfide TS: tetramethyl turum monosulfide M: 2-mercaptobenzothiazole D: diphenylguanidine

[0039]

According to the present invention, a rubber composition having high hardness and excellent tensile strength was obtained without impairing the workability during kneading, as is apparent from Table 1.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 AC011 AC031 AC051 AC061 AC071 AC081 AC091 AC111 BB151 BB181 BB241 BB271 BD121 BG041 CD012 CD022 CD042 CD052 CD062 CD112 CD122 CD132 CD142 CD182 CH021 CH041 CK021 CP0347 DE0136 DE0106 DG046 DG056 DJ006 DJ036 DJ046 DJ056 DK006 DL006 EE057 EK037 EK047 EN037 EN047 EN077 ES017 ET007 EW177 FA046 FD016 FD030 FD070 FD147 FD150 FD170 FD200 FD320 GM01 GN01 GQ01

Claims (8)

[Claims] 1. A rubber, an epoxy resin and a vulcanizing agent,
A rubber composition containing no alkylphenol-formaldehyde resin. 2. The rubber composition according to claim 1, wherein the rubber is a butadiene rubber. 3. The rubber composition according to claim 2, wherein the butadiene rubber is styrene-butadiene rubber or butadiene rubber. 4. The rubber composition according to claim 1, which contains 0.5 to 100 parts by weight of an epoxy resin based on 100 parts by weight of the rubber. 5. The rubber composition according to claim 1, wherein the epoxy resin is a novolak epoxy resin, a cresol novolak epoxy resin, a bisphenol A epoxy resin, or a bisphenol F epoxy resin. 6. The rubber composition according to claim 1, wherein the epoxy resin has an epoxy equivalent of 500 or less. 7. A rubber composition containing 30 to 2 fillers per 100 parts by weight of rubber.
The rubber composition according to any one of claims 1 to 6, comprising 00 parts by weight. 8. A molded article of the rubber composition according to any one of claims 1 to 7.