JP2009035571A - Acrylic rubber composition - Google Patents

Abstract

The present invention provides an acrylic rubber composition and a vulcanized product thereof having a small change rate of tensile strength and elongation before and after heat treatment.
An acrylic rubber composition containing 25 to 90% by mass of a carboxyl group-containing ethylene-acrylic rubber and 10 to 75% by mass of an epoxy group-containing ethylene-acrylic rubber and a vulcanizing agent. What a vulcanizing agent contains 0.1-10 mass parts of guanidine compounds and 0.01-10 mass parts of diamine compounds with respect to 100 mass parts of acrylic rubber is preferable.

Description

  The present invention relates to an acrylic rubber composition, and more particularly to an acrylic rubber composition having a small change rate of tensile strength and elongation before and after heat treatment when a vulcanized product is obtained.

  Acrylic rubber and its vulcanizates have excellent physical properties such as heat resistance, oil resistance, mechanical properties and compression set properties, and are used for hose parts, seal parts, and vibration-proof rubber parts in automobile engine rooms. It is used as a material. However, these parts are required to have higher heat resistance than ever because of high heat of use environment.

  Moreover, the improvement of the vulcanization | cure rate of acrylic rubber itself is calculated | required for the purpose of the productivity improvement.

  As an acrylic rubber composition corresponding to such a requirement, an acrylic rubber composition having a carboxyl group as a crosslinking point is known (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 11-1000047

  The acrylic rubber composition having a carboxyl group as a crosslinking point is a material that has a balance of vulcanization speed, mechanical properties, compression set properties, heat resistance, etc., but the use conditions have become more severe. Improvement of heat resistance is required, and development of an acrylic rubber composition capable of reducing the rate of change in tensile strength and elongation before and after heat treatment is particularly desired when a vulcanized product is used.

  The present invention provides an acrylic rubber composition and a vulcanized product thereof having a small change rate of tensile strength and elongation before and after heat treatment when the vulcanized product is used.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that an acrylic rubber having a specific ratio of a carboxyl group-containing ethylene-acrylic rubber and an epoxy group-containing ethylene-acrylic rubber, and a vulcanizing agent It was found that an acrylic rubber composition containing a small amount of change in tensile strength and elongation before and after heat treatment was obtained when a vulcanized product was obtained using an acrylic rubber composition containing the present invention. That is, the present invention relates to an acrylic rubber composition containing 25 to 90% by mass of a carboxyl group-containing ethylene-acrylic rubber and 10 to 75% by mass of an epoxy group-containing ethylene-acrylic rubber and a vulcanizing agent. is there. The present invention also relates to a vulcanized product obtained by vulcanizing this acrylic rubber composition.

  When the acrylic rubber composition of the present invention is a vulcanized product, a composition having a small change in tensile strength and elongation before and after heat treatment can be obtained.

  The acrylic rubber composition contains 25 to 90% by mass of a carboxyl group-containing ethylene-acrylic rubber, 10% to 75% by mass of an epoxy group-containing ethylene-acrylic rubber, and a vulcanizing agent. Moreover, the vulcanizate can be used as a good hose part, seal part, and vibration-proof rubber part.

The carboxyl group-containing ethylene-acrylic rubber is a copolymer of a carboxyl group-containing unsaturated fatty acid and an unsaturated monomer such as ethylene and alkyl acrylate using a known method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization. It is obtained by polymerization.
Examples of the carboxyl group-containing unsaturated fatty acid include unsaturated carboxylic acids such as acrylic acid and methacrylic acid, aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid, or monomethyl malate and monoethyl maleate. , Mono-n-propylmalate, monoisopropylmalate, mono-n-butylmalate, monoisobutylmalate, monomethylfumarate, monoethylfumarate, mono-n-propylfumarate, monoisopropylfumarate, mono- n-butyl fumarate, monoisobutyl fumarate, monomethyl itaconate, monoethyl itaconate, mono-n-propyl itaconate, mono-n-propyl citraconate, mono-n-butyl citraconate, monoisobutyl citraconic Fatty dicarbo such as nate There is acid monoester or the like may be used in combination as the two or more not only these alone. The proportion of the carboxyl group-containing unsaturated fatty acid is preferably from 0.1 to 30% by mass of the entire carboxyl group-containing ethylene-acrylic rubber. More preferably, it is 0.3-10 mass%, Most preferably, it is 1-5 mass%.

  The proportion of ethylene is preferably 0.1 to 10% by mass of the entire carboxyl group-containing ethylene-acrylic rubber. More preferably, it is 0.3-5 mass%, Most preferably, it is 0.5-2.9 mass%.

  Examples of the acrylic acid alkyl ester include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate.

N-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, cyanomethyl acrylate, 1-cyanoethyl acrylate, 2-cyanoethyl acrylate, 1-cyanopropyl acrylate, 2-cyanopropyl acrylate, 3-cyanopropyl acrylate, 4 -Cyanobutyl acrylate, 6-cyanohexyl acrylate, 2-ethyl-6-cyanohexyl acrylate, 8-cyanooctyl acrylate and the like.
2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2- (n-propoxy) ethyl acrylate, 2- (n-butoxy) ethyl acrylate, 3-methoxypropyl acrylate, 3-ethoxypropyl acrylate, 2- (n-propoxy) ) Acrylic acid alkoxyalkyl esters such as propyl acrylate and 2- (n-butoxy) propyl acrylate may be used.

  Further, 1,1-dihydroperfluoroethyl (meth) acrylate, 1,1-dihydroperfluoropropyl (meth) acrylate, 1,1,5-trihydroperfluorohexyl (meth) acrylate, 1,1,2,2-tetrahydro Fluorine-containing compounds such as perfluoropropyl (meth) acrylate, 1,1,7-trihydroperfluoroheptyl (meth) acrylate, 1,1-dihydroperfluorooctyl (meth) acrylate, 1,1-dihydroperfluorodecyl (meth) acrylate ( Hydroxyl group-containing (meth) acrylic acid ester such as (meth) acrylic acid ester, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, diethylaminoethyl (meta) Acrylates, tertiary amino group-containing, such as dibutyl aminoethyl (meth) acrylate (meth) acrylic acid ester, and the like may be used methacrylic acid esters such as methyl acrylate, octyl methacrylate.

  These unsaturated monomers such as acrylic acid alkyl esters may be used alone or in combination of two or more. The proportion of the unsaturated monomer such as alkyl acrylate is preferably 60 to 99.8% by mass of the entire carboxyl group-containing ethylene-acrylic rubber. More preferably, it is 85-99.4 mass%, Most preferably, it is 92.1-98.5 mass%.

Epoxy group-containing ethylene-acrylic rubber is a combination of an epoxy group-containing unsaturated monomer and an unsaturated monomer such as ethylene and alkyl acrylate using known methods such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization. It is obtained by polymerization.
Examples of the epoxy group-containing unsaturated monomer include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, and the like. The proportion of the epoxy group-containing unsaturated monomer is preferably 0.1 to 10% by mass of the entire epoxy group-containing ethylene-acrylic rubber. More preferably, it is 0.3-5 mass%, Most preferably, it is 1-3 mass%.

  The proportion of ethylene is preferably 0.1 to 10% by mass of the entire epoxy group-containing ethylene-acrylic rubber. More preferably, it is 0.3-5 mass%, Most preferably, it is 0.5-2.9 mass%.

  Examples of the acrylic acid alkyl ester include, for example, the acrylic acid alkyl ester, acrylic acid alkoxyalkyl ester, fluorine-containing (meth) acrylic acid ester, hydroxyl group-containing (meta ) Acrylic acid ester, tertiary amino group-containing (meth) acrylic acid ester, methacrylic acid ester and the like can be used, and not only these simple substances but also two or more kinds may be used in combination. The proportion of the unsaturated monomer such as alkyl acrylate is preferably 60 to 99.8% by mass of the entire epoxy group-containing ethylene-acrylic rubber. More preferably, it is 85-99.4 mass%, Most preferably, it is 92.1-98.5 mass%.

The carboxyl group-containing ethylene-acrylic rubber and the epoxy group-containing ethylene-acrylic rubber may be copolymerized with other monomers copolymerizable with the above-mentioned monomers within a range not impairing the object of the present invention. .
Other monomers that can be copolymerized are not particularly limited, and examples thereof include alkyl vinyl ketones such as methyl vinyl ketone, vinyl and ethers such as vinyl ethyl ether and allyl methyl ether, styrene, α- Vinyl aromatic compounds such as methylstyrene, chlorostyrene, vinyltoluene, vinylnaphthalene, vinylnitriles such as acrylonitrile and methacrylonitrile, acrylamide, vinyl acetate, ethylene, propylene, butadiene, isoprene, pentadiene, vinyl chloride, vinylidene chloride, fluorine Ethylenically unsaturated compounds such as vinyl fluoride, vinylidene fluoride, vinyl propionate, alkyl fumarate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether Epoxy group-containing compound such as ether, 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, vinyl benzyl chloride, vinyl chloroacetate, are active chlorine-containing compounds such as allyl chloroacetate.

The ratio of the carboxyl group-containing ethylene-acrylic rubber in the acrylic rubber composition is 25 to 90% by mass, preferably 50 to 75% by mass. When the proportion of the carboxyl group-containing ethylene-acrylic rubber is less than 25% by mass, the compression set characteristic when the vulcanized product is obtained is inferior. When the proportion exceeds 90% by mass, the tensile strength before and after the heat treatment when the vulcanized product is obtained. The effect on the rate of change is poor.
The proportion of the epoxy group-containing ethylene-acrylic rubber is 10 to 75% by mass, preferably 25 to 50% by mass. When the ratio of the epoxy group-containing ethylene-acrylic rubber exceeds 75% by mass, the compression set characteristic when the vulcanized product is inferior, and when it is less than 10% by mass, the tensile strength before and after the heat treatment when the vulcanized product is used. The effect on the rate of change in strength is poor.

  A vulcanizing agent vulcanizes an acrylic rubber having a carboxyl group-containing ethylene-acrylic rubber and an epoxy group-containing ethylene-acrylic rubber to improve its tensile strength, compression set characteristics, and the like. Although it does not specifically limit as a vulcanizing agent, What has a guanidine compound and a diamine compound is good.

  Examples of the guanidine compound include guanidine, tetramethylguanidine, dibutylguanidine, diphenylguanidine, di-o-tolylguanidine, and di-o-tolylguanidine is preferably used.

  Although the addition amount of a guanidine compound is not particularly limited, it is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of acrylic rubber from the viewpoint that a good vulcanization reaction can be obtained, and 0.3 to 5 Part by mass is more preferable.

Examples of the diamine compound include aliphatic diamines such as hexamethylenediamine, hexamethylenediamine carbamate, triethylenetetramine, and tetraethylenepentamine, 4,4′-diaminodicyclohexylmethane, 3,3′-dimethyl4,4′-. Alicyclic diamines such as diaminodicyclohexylmethane, 1,3-bis (aminomethyl) cyclohexane, dihydrazides such as adipic acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, 4,4′-methylenedianiline, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-toluylenediamine, m-toluylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, represented by the following structural formula (1) Good An aromatic diamine represented by the general formula (Chemical Formula 2) is preferably used from the viewpoint that there is an aromatic diamine and the like and the processing stability is good.
(Chemical Formula 2) H ₂ N-ph-M-ph-NH ₂
(In the formula, ph represents a benzene ring. M represents one of O, S, SO ₂ , CONH or O—R—O. Here, R in O—R—O represents ph, _{ph-ph, ph-SO 2} -ph, (CH 2) m, represents one of the _{ph-C (CX 3) 2} -ph. further, m is 3-5 integer, X is, H, F or one of (CH ₂ ) C (CH ₃ ) ₂ (CH ₂ ) is represented.)

  Examples of the compound of the general formula (Formula 2) include 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-diaminodiphenyl sulfide, 1,3-bis (4-aminophenoxy) -2, 2-dimethylpropane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) pentane, 2,2-bis [ 4- (4-aminophenoxy) phenyl] propane, 4,4′-diaminodiphenylsulfone, bis (4-3-aminophenoxy) phenylsulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] hexa Fluoropropane, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzani De, and the like bis [4- (4-aminophenoxy) phenyl] sulfone.

  Although the addition amount of a diamine compound is not specifically limited, 0.01-10 mass parts is preferable with respect to 100 mass parts of acrylic rubber from a viewpoint that a favorable vulcanization reaction is obtained, 0.05-5 Part by mass is more preferable.

  In the acrylic rubber composition, a monoamine compound such as a primary amine compound, a secondary amine compound, or a tertiary amine compound may be blended for the purpose of improving processability during kneading.

  Examples of the primary amine compound include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tetradecylamine, hexadodecylamine, Stearylamine, octadecylamine, eicosylamine, methanolamine, ethanolamine, aniline, cyclohexylamine, benzylamine, 2-aminotoluene, 3-aminotoluene, 4-aminotoluene, 2,4-dimethylaniline, 2,3- Dimethylaniline, 2,5-dimethylaniline, 2,6-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2,4,5-trimethylaniline, 2,4,6-trime Ruaniline, 3,4,5,6-tetramethylaniline, 2,4,5,6-tetramethylaniline, 2,3,5,6-tetramethylaniline, 2-ethyl-3-hexylaniline, 2-ethyl -4-hexylaniline, 2-ethyl-5-hexylaniline, 2-ethyl-6-hexylaniline, 3-ethyl-4-hexylaniline, 3-ethyl-5-hexylaniline, 3-ethyl-2-hexylaniline 4-ethyl-2-hexylaniline, 5-ethyl-2-hexylaniline, 4-ethyl-3-hexylaniline, 6-ethyl-2-hexylaniline, 5-ethyl-3-hexylaniline, 3,4, 6-triethylaniline, 2-methoxyaniline, 3-methoxyaniline, 4-methoxyaniline, 2-methoxy-3-methylaniline 2-methoxy-4-methylaniline, 2-methoxy-5-methylaniline, 2-methoxy-6-methylaniline, 3-methoxy-2-methylaniline, 3-methoxy-4-methylaniline, 3-methoxy-5 -Methylaniline, 3-methoxy-6-methylaniline, 4-methoxy-2-methylaniline, 4-methoxy-3-methylaniline, 2-ethoxyaniline, 3-ethoxyaniline, 4-ethoxyaniline, 4-methoxy- 5-methylaniline, 4-methoxy-6-methylaniline, 2-methoxy-3-ethylaniline, 2-methoxy-4-ethylaniline, 2-methoxy-5-ethylaniline, 2-methoxy-6-ethylaniline, 3-methoxy-2-ethylaniline, 3-methoxy-4-ethylaniline, 3-methoxy-5-ethyl Ruaniline, 3-methoxy-6-ethylaniline, 4-methoxy-2-ethylaniline, 4-methoxy-3-ethylaniline, 2-methoxy-2,3,4-trimethylaniline, 3-methoxy-2,4 There are 5-trimethylaniline, 4-methoxy-2,3,5-trimethylaniline, bis (2-cyanoethyl) amine and the like.

  Examples of secondary amine compounds include dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditetradecylamine. , Dihexadecylamine, dimethanolamine, diethanolamine, diphenylamine, dicyclohexylamine, nitrosodimethylamine, nitrosodiphenylamine, and the like.

  Examples of the tertiary amine compound include trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, triundecylamine, Examples include dodecylamine, tritetradecylamine, trihexadecylamine, tristearylamine, trioctadecylamine, trieicosylamine, trimethanolamine, triethanolamine, triphenylamine, and trocyclohexylamine.

  The addition amount of these monoamine compounds is not particularly limited, but is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of acrylic rubber from the viewpoint of improving processability and vulcanized properties. 0.05-2 mass parts is still more preferable.

  Acrylic rubber compositions can be molded and vulcanized by adding fillers, reinforcing agents, plasticizers, lubricants, anti-aging agents, stabilizers, silane coupling agents, etc., depending on the purpose when they are put to practical use. it can.

In addition, fillers and reinforcing agents such as carbon black, silica, clay, talc and calcium carbonate may be added in view of required rubber properties.
The total amount of these additives added is preferably 30 to 100 parts by mass with respect to 100 parts by mass of the acrylic rubber.

As the plasticizer, plasticizers used for ordinary rubber applications can be added, and are not particularly limited. For example, ester plasticizers, polyoxyethylene ether plasticizers, trimellitate plasticizers. and so on.
The addition amount of the plasticizer is preferably up to about 50 parts by mass with respect to 100 parts by mass of the acrylic rubber.

  As the apparatus for kneading, molding and vulcanizing the acrylic rubber composition and the apparatus for kneading and molding the vulcanized product of the acrylic rubber composition, those usually used in the rubber industry can be used.

The acrylic rubber composition and the vulcanized product thereof are particularly suitably used as seal parts such as rubber hoses, gaskets and packing, and vibration-proof rubber parts. Examples of rubber hoses include transmission oil cooler hoses, engine oil cooler hoses, air duct hoses, turbo intercooler hoses, hot air hoses, radiator hoses, power steering hoses, fuel hoses, drains for automobiles, construction machinery, hydraulic equipment, etc. There are system hoses.
Seal parts include, for example, engine head cover gasket, oil pan gasket, oil seal, lip seal packing, O-ring, transmission seal gasket, crankshaft, camshaft seal gasket, valve stem, power steering seal belt cover seal, constant speed There are joint boot materials and rack and pinion boot materials.
Anti-vibration rubber parts include, for example, a damper pulley, a center support cushion, and a suspension bush.

As a structure of the rubber hose, not only a single-layer hose obtained from the acrylic rubber composition and the vulcanized product thereof, but also a layer made of the acrylic rubber composition and the vulcanized product, for example, fluorine rubber, fluorine-modified acrylic rubber, A multi-layer hose in which hydrin rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene rubber, silicone rubber, chlorosulfonated polyethylene rubber and the like are combined as an inner layer, an intermediate layer, or an outer layer may be used.
Further, as is generally done, reinforcing yarns or wires may be provided in the middle of the hose or in the outermost layer of the rubber hose.

Production of carboxyl group-containing ethylene-acrylic rubber In a pressure-resistant reaction vessel having an internal volume of 40 liters, ethyl acrylate 7.8 kg, n-butyl acrylate 3.4 kg, monobutyl maleate 0.5 kg, partially saponified polyvinyl alcohol 4% by mass 17 kg of aqueous solution and 22 g of sodium acetate were added and mixed well in advance with a stirrer to prepare a uniform suspension. After replacing the air in the upper part of the tank with nitrogen, ethylene was injected into the upper part of the tank and the pressure was adjusted to 20 kg / cm ² . Stirring was continued, and the inside of the tank was maintained at 55 ° C., and then an aqueous t-butyl hydroperoxide solution was injected from a separate inlet to initiate polymerization. During the reaction, the temperature in the tank was maintained at 55 ° C., and the reaction was completed in 6 hours. A sodium borate aqueous solution was added to the resulting polymerization solution to solidify the polymer, followed by dehydration and drying to obtain a carboxyl group-containing ethylene-acrylic rubber.

Production of epoxy group-containing ethylene-acrylic rubber A In a pressure-resistant reaction vessel with an internal volume of 40 liters, vinyl acetate 2.8 kg, ethyl acrylate 4.5 kg, n-butyl acrylate 3.9 kg, glycidyl methacrylate 170 g, partially saponified 17 kg of a 4% by weight aqueous solution of polyvinyl alcohol and 22 g of sodium acetate were added and mixed well in advance with a stirrer to prepare a uniform suspension. After replacing the air in the upper part of the tank with nitrogen, ethylene was injected into the upper part of the tank and the pressure was adjusted to 50 kg / cm ² . Stirring was continued, and the inside of the tank was maintained at 55 ° C., and then an aqueous ammonium persulfate solution was press-fitted through a separate inlet to initiate polymerization. During the reaction, the temperature in the tank was maintained at 55 ° C., and the reaction was completed in 6 hours. An aqueous sodium borate solution was added to the resulting polymerization solution to solidify the polymer, followed by dehydration and drying to obtain an epoxy group-containing ethylene-acrylic rubber A.

Production of epoxy group-containing ethylene-acrylic rubber B In a pressure resistant reaction vessel with an internal volume of 40 liters, 10.1 kg of ethyl acrylate, 1.1 kg of n-butyl acrylate, 120 g of glycidyl methacrylate, 4% by mass of partially saponified polyvinyl alcohol 17 kg of an aqueous solution and 22 g of sodium acetate were added and mixed well in advance with a stirrer to prepare a uniform suspension. After replacing the air in the upper part of the tank with nitrogen, ethylene was injected into the upper part of the tank and the pressure was adjusted to 20 kg / cm ² . Stirring was continued, and the inside of the tank was maintained at 55 ° C., and then an aqueous t-butyl hydroperoxide solution was injected from a separate inlet to initiate polymerization. During the reaction, the temperature in the tank was maintained at 55 ° C., and the reaction was completed in 6 hours. An aqueous sodium borate solution was added to the resulting polymerization solution to solidify the polymer, followed by dehydration and drying to obtain an epoxy group-containing ethylene-acrylic rubber B.

Examples 1-7, Comparative Examples 1-6
Each material shown in Table 1 was kneaded using an 8-inch roll to obtain an acrylic rubber composition. The resulting acrylic rubber composition was heat treated at 170 ° C. for 20 minutes with a steam heating type hot press to form a primary vulcanizate, and then heat treated with hot air (gear oven) at 170 ° C. for 4 hours. Thus, a vulcanized product of an acrylic rubber composition was obtained.
About the vulcanizate of the obtained acrylic rubber composition, compression set, tensile strength, elongation at break, hardness and heat resistance were evaluated.
The compression set test was measured according to JIS K6262 (test condition: 150 ° C. × 70 hours), and the tensile strength and elongation at break were measured according to JIS K6251. The hardness is measured using a durometer hardness meter in accordance with JIS K6253, and the heat resistance is in accordance with JIS K6257, after the heat treatment at 200 ° C. for 70 hours. Tensile strength and elongation were measured, and each rate of change was determined using the general formula (Equation 1). The change rate indicates that the smaller the absolute value, the better the heat resistance.

  In Table 1, the anti-aging agent is Nowguard 445 manufactured by Uniroyal, Carbon Black is Seest 3 manufactured by Tokai Carbon Co., Ltd., Liquid Paraffin is High Coal K-230 manufactured by Kaneda Corporation, and Stearylamine is Farmin manufactured by Kao Corporation. 80 was used. Commercially available products were used for the other materials.

As shown in comparison between the examples and the comparative examples, when the acrylic rubber composition of the present invention is a vulcanized product, a composition having a small change in tensile strength and elongation before and after heat treatment is obtained.

The acrylic rubber composition of the present invention has a low rate of change in tensile strength and elongation before and after heat treatment when used as a vulcanized product. The acrylic rubber composition and its vulcanized product are used for hose parts, seal parts, It can be used as a vibration rubber part.

Claims (4)

An acrylic rubber composition containing an acrylic rubber having 25 to 90% by mass of a carboxyl group-containing ethylene-acrylic rubber and 10 to 75% by mass of an epoxy group-containing ethylene-acrylic rubber, and a vulcanizing agent. The acrylic resin according to claim 1, wherein the vulcanizing agent contains 0.1 to 10 parts by mass of a guanidine compound and 0.01 to 10 parts by mass of a diamine compound with respect to 100 parts by mass of the acrylic rubber. Rubber composition. The acrylic rubber composition according to claim 2, wherein the diamine compound is at least one compound represented by the general formula (Chemical Formula 1).
(Chemical Formula 1) H ₂ N-ph-M-ph-NH ₂
(In the formula, ph represents a benzene ring. M represents one of O, S, SO ₂ , CONH or O—R—O. Here, R in O—R—O represents ph, _{ph-ph, ph-SO 2} -ph, (CH 2) m, represents one of the _{ph-C (CX 3) 2} -ph. further, m is 3-5 integer, X is, H, F or one of (CH ₂ ) C (CH ₃ ) ₂ (CH ₂ ) is represented.) A vulcanized product obtained by vulcanizing the acrylic rubber composition according to any one of claims 1 to 3.