JP2001240716A - Crosslinkable acrylic rubber composition and crosslinked article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crosslinked acrylic rubber article which is excellent in tensile strength and undergoes little changes in tensile strength and tensile stress due to thermal load. SOLUTION: A crosslinkable acrylic rubber composition containing 100 pts.wt. acrylic rubber having units derived from an ethylenically unsaturated polycarboxylic incomplete ester (a) and units derived from a nonhalogenous unsaturated monomer (b) and 0.1-20 pts.wt. polyvalent amine crosslinker is cross-linked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinkable acrylic rubber composition having excellent tensile strength and capable of obtaining a crosslinked product having a small change in tensile strength and a small change in tensile stress due to heat load, and a crosslinked product thereof.

[0002]

2. Description of the Related Art Acrylic rubber has excellent heat resistance.
It is widely used in automobile-related fields. But,
There has been a strong demand for better thermal stability, and improvements have been made.

As a crosslinked acrylic rubber having excellent tensile strength and heat stability, a crosslinked product obtained by crosslinking an acrylic rubber obtained by copolymerizing butenedioic acid monoester as a crosslinking monomer with a polyvalent amine crosslinking agent is known. (Japanese Patent Laid-Open No. 50-
No. 45031). However, there is a need for crosslinked products having better tensile strength and heat stability.

Unsaturated dicarboxylic acids such as fumaric acid, maleic acid and itaconic acid and acrylates and, if desired, 0.1 to 10% by weight of crosslinkable monomers such as N-methylolacrylamide and methylacrylamide glycolate methyl ether. A crosslinked product obtained by neutralizing a copolymerized acrylic rubber with ammonia and then thermally crosslinking the same is also known (Japanese Patent Application Laid-Open No. 1-501480). However, in this case, when the generated acid-containing polymer is neutralized with an alkali,
While ionic cross-linking occurs and the tensile strength is increased, the cross-linked product has a problem that the tensile strength and the tensile stress are greatly reduced by heat load. In addition, the non-neutralized cross-linked product cross-linked with a polyvalent amine cross-linking agent has a problem that, similarly to the neutralized one, the tensile strength and the tensile stress are greatly reduced by heat load.

It is known that an acrylic rubber obtained by copolymerizing a carboxyl group-containing monomer and a halogen-containing monomer is crosslinked with an alkali metal carboxylate (Japanese Patent Laid-Open No. 49-49).
-80155, JP-A-50-56438,
JP-A-54-83047. However, this crosslinked product has a problem that the change in tensile strength due to heat load is large.

[0006] It is also known to crosslink a halogen-containing acrylic rubber with a polyamine crosslinker (Japanese Patent Publication No. Sho-46).
No. 41607). However, this crosslinked product also has a problem that a change in tensile strength and a change in tensile stress due to heat load are large.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an acrylic rubber crosslinked product which has a higher tensile strength and a smaller change in tensile strength and tensile stress due to heat load than conventional ones. It is in.

The present inventors have conducted intensive studies to achieve the above object, and as a result, as a crosslinkable monomer, an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) and a halogen-containing unsaturated monomer. The present inventors have found that the above object can be achieved by crosslinking an acrylic rubber obtained by copolymerizing the monomer (b) with a polyvalent amine crosslinking agent, thereby completing the present invention.

[0009]

Thus, according to the present invention, an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a halogen-containing unsaturated monomer (b) are provided.
Provided is a crosslinkable acrylic rubber composition containing 100 parts by weight of an acrylic rubber containing a unit and 0.1 to 20 parts by weight of a polyvalent amine crosslinking agent.

According to the present invention, there is provided a crosslinked product obtained by crosslinking the crosslinkable acrylic rubber composition.

[0011]

DETAILED DESCRIPTION OF THE INVENTION [Crosslinkable Acrylic Rubber Composition] The crosslinkable acrylic rubber composition of the present invention comprises an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a halogen-containing unsaturated monomer. It contains 100 parts by weight of an acrylic rubber containing a monomer (b) unit and 0.1 to 20 parts by weight of a polyamine crosslinking agent.

Acrylic Rubber The acrylic rubber used in the present invention contains an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a halogen-containing unsaturated monomer (b) unit. .

Acrylic rubber is a rubber having a structure in which a skeleton structure is obtained by homopolymerizing an acrylate monomer or a structure in which an acrylate monomer and an alkyl acrylate monomer are copolymerized. The acrylic rubber used in the present invention comprises a crosslinkable monomer, an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) and a halogen-containing unsaturated monomer (b). And copolymerized.

As the alkyl acrylate monomer, those having an alkyl group having 1 to 8 carbon atoms are preferable, and those having an alkyl group having 2 to 4 carbon atoms are particularly preferable. As alkyl acrylate monomers, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isopropyl acrylate, isobutyl acrylate, n-hexyl acrylate,
Examples thereof include 2-ethylhexyl acrylate and cyclohexyl acrylate. Particularly, ethyl acrylate and n-butyl acrylate are preferred. These acrylic acid alkyl ester monomers may be used in combination of two or more.

[0015] The lower limit of the content of the alkyl acrylate monomer unit in the acrylic rubber is preferably 30% by weight, more preferably 60% by weight, particularly preferably 75% by weight, and the upper limit is preferably 99. 9% by weight, more preferably 99.5% by weight, particularly preferably 99% by weight
It is.

As the alkoxyalkyl acrylate monomer, those having an alkoxyalkyl group having 2 to 16 carbon atoms are preferable, and those having an alkoxyalkyl group having 2 to 8 carbon atoms are particularly preferable. Such alkoxy acrylate alkyl acrylate monomers include methoxymethyl acrylate, ethoxymethyl acrylate,
2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-propoxyethyl acrylate, 2-butoxyethyl acrylate, 3-methoxypropyl acrylate, 4-methoxybutyl acrylate, and the like.
In particular, 2-methoxyethyl acrylate, 2-methoxy acrylate
Ethoxyethyl is preferred.

The lower limit of the content of the alkoxyalkyl acrylate monomer unit in the acrylic rubber is preferably 3% by weight, more preferably 5% by weight, particularly preferably 7% by weight.
% By weight, and the upper limit is preferably 50% by weight, more preferably 30% by weight, and particularly preferably 20% by weight. If the content of the alkoxyalkyl acrylate monomer unit is too small, the oil resistance of the crosslinked product may be poor or the cold resistance may be poor. If the content is too large, elongation or the like may be reduced after heat load.

The incompletely ethylenically unsaturated polyvalent carboxylic acid alkyl ester monomer (a) is a monomeric monomer in which at least one carboxyl group of a polycarboxylic acid having an ethylenically unsaturated bond is esterified with an alkyl group. And also wherein at least one carboxyl group remains unesterified by an alkyl group. Among them, monoalkyl esters of ethylenically unsaturated dicarboxylic acids are preferred, and monoalkyl butenedionates are particularly preferred.

Examples of the monoalkyl butenedionate include monomethyl fumarate, monoethyl fumarate, mono-n-propyl fumarate, monoisopropyl fumarate, mono-n-butyl fumarate, mono-2-ethylhexyl fumarate and mono-2-fumarate. Monoesters of fumaric acid such as methoxyethyl; monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, mono-isopropyl maleate, mono-n-butyl maleate, mono 2-ethylhexyl maleate, mono maleate 2 Maleic acid monoester monomers such as -methoxyethyl; and the like. Particularly preferred are monoalkyl fumarate monomers such as monomethyl fumarate, monoethyl fumarate and mono-n-butyl fumarate.

The lower limit of the unit content of the ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) in the acrylic rubber is preferably 0.005% by weight, more preferably 0.1% by weight.
It is preferably 0.05% by weight, particularly preferably 0.2% by weight, and the upper limit is preferably 19% by weight, more preferably 9% by weight, and particularly preferably 4% by weight. If the unit content of the ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit is too small, the change in tensile strength and the change in tensile stress due to heat load increases or the cross-linking is not sufficiently performed, so that the shape of the cross-linked product cannot be maintained. If the amount is too large, the change in tensile strength and the change in tensile stress due to heat load may increase, or the crosslinked product may become hard and lose rubber elasticity.

The halogen-based crosslinkable monomer (b) is a monomer which is copolymerizable with the alkyl acrylate monomer and contains a halogen atom. For example, halogen-containing aromatic vinyl compounds such as p-chlorostyrene, chloromethylstyrene, and bromomethylstyrene; unsaturated alcohol esters of halogen-containing saturated carboxylic acids such as vinyl chloroacetate and allyl chloroacetate; chloromethyl vinyl ether; Halogen-containing unsaturated ethers such as -chloroethyl vinyl ether; haloalkyl acrylates such as chloromethyl acrylate and 2-chloroethyl acrylate; haloalkyl methacrylates such as chloromethyl methacrylate and 2-chloroethyl methacrylate; chloroacrylate Acetoxymethyl, acrylic acid-
Haloacyloxyalkyl acrylates such as 2- (chloroacetoxy) ethyl acrylate; halogen-containing unsaturated nitriles such as α-chloroacrylonitrile and α-chloromethylacrylonitrile; halogenated olefins such as vinyl chloride and vinylidene chloride; Chloro-
Examples thereof include halogen-containing dienes such as 1,3-butadiene and 1,2-dichloro-1,3-butadiene. Among them, monomers containing chlorine as a halogen atom are preferable, and chlorine-containing aromatic vinyl compounds are particularly preferable.

The lower limit of the unit content of the halogen-containing monomer (b) in the acrylic rubber is preferably 0.005% by weight, more preferably 0.05% by weight, particularly preferably 0.2% by weight, and the upper limit. Is preferably 19% by weight,
It is more preferably 9% by weight, particularly preferably 4% by weight. If the unit content of the halogen-containing monomer (b) is too small, a change in tensile strength and a change in tensile stress due to a heat load may increase or the cross-linking may not be sufficiently performed, so that the shape of the cross-linked product may not be maintained. (B) If the unit content is too large, the change in tensile strength and the change in tensile stress due to heat load may increase, or the crosslinked product may become hard and lose rubber elasticity.

Ethylenically unsaturated polycarboxylic acid incomplete esterified ethylenically unsaturated polycarboxylic acid (A) unit and halogen-containing monomer (b) unit content in acrylic rubber Incomplete ester monomer (a)
The lower limit of the unit amount is preferably 5% by weight, more preferably 10% by weight, particularly preferably 20% by weight, and the upper limit is preferably 95% by weight, more preferably 90% by weight, particularly preferably 80% by weight. It is. If the unit amount of the ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) is too small or too large, the change in tensile strength and the change in tensile stress due to heat load may increase.

The lower limit of the total amount of the ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and the halogen-containing monomer (b) unit in the acrylic rubber is preferably 0.1% by weight. %, More preferably 0.5% by weight, particularly preferably 1% by weight, and the upper limit is preferably 20% by weight, more preferably 10% by weight, particularly preferably 5% by weight. If the proportion of the total amount is too small, the crosslinked product is not sufficiently crosslinked, so that the shape of the crosslinked product may not be maintained. If the proportion is too large, the crosslinked product may become hard and lose rubber elasticity.

The acrylic rubber may be obtained by polymerizing a monomer copolymerizable with these monomers in addition to these monomers. Examples of such a monomer include α, β-unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; α-olefins such as ethylene and propylene; and aromatic vinyl monomers such as styrene and α-methylstyrene. Vinyl monomers such as vinyl acetate, ethyl vinyl ether and butyl vinyl ether; acrylic acid derivative monomers other than those described above such as furfuryl acrylate and acrylamide; methacrylic acid derivatives such as alkoxyalkyl methacrylate and methacrylamide Monomers; conjugated diene monomers such as isoprene, butadiene and piperylene; dicyclopentadiene, norbornene,
Non-conjugated diene monomers such as ethylidene norbornene, hexadiene and norbornadiene; and polyfunctional monomers such as divinylbenzene, ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, and propylene glycol dimethacrylate.

The lower limit of the content of these copolymerizable monomers in the acrylic rubber is preferably 30% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight.
It is as follows. If the content of these monomers is too large, the tensile strength may decrease, or the rate of change in tensile strength due to heat load may increase.

Mooney viscosity of acrylic rubber (ML _{1 + 4} ,
The lower limit of (100 ° C.) is preferably 10, more preferably 15, and particularly preferably 20, and the upper limit is preferably 70, more preferably 60, and particularly preferably 50. If the Mooney viscosity is too low, the moldability or the mechanical strength of the crosslinked product may be poor, and if too large, the moldability may be poor.

Polyamine Crosslinking Agent In the present invention, a polyamine crosslinking agent is used as a crosslinking agent.

Examples of the polyvalent amine crosslinking agent include an aliphatic polyamine crosslinking agent and an aromatic polyamine crosslinking agent. Examples of the aliphatic polyamine crosslinking agent include hexamethylene diamine, hexamethylene diamine carbamate, N,
N′-dicinnamylidene-1,6-hexanediamine and the like, and examples of the aromatic polyamine crosslinking agent include 4,4
4'-methylene dianiline, m-phenylenediamine,
4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 '-(m-phenylenediisopropylidene) dianiline, 4,4'-(p-
Phenylenediisopropylidene) dianiline, 2,2 '
-Bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminobenzanilide, 4,4'-
Bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-
Examples include benzenetriamine and 1,3,5-benzenetri (aminomethyl). Of these, aromatic polyamine crosslinkers are particularly preferred.

The lower limit of the amount of the polyamine crosslinking agent per 100 parts by weight of the acrylic rubber is 0.1 part by weight, preferably 0.2 part by weight, particularly preferably 0.3 part by weight.
The upper limit is 10 parts by weight, preferably 7 parts by weight, particularly preferably 5 parts by weight. If the amount of the polyamine crosslinking agent is too small, crosslinking is not sufficiently performed, and it is difficult to maintain the shape of the crosslinked product. If the amount is too large, the crosslinked product becomes too hard and the elasticity of the crosslinked rubber is impaired.

A crosslinking accelerator can be used together with the polyamine crosslinking agent. The crosslinking accelerator used in combination with the polyamine crosslinking agent has a base dissociation constant of 10 ⁻¹² to 10 ⁺⁶ at 25 ° C. in water, and substantially reacts with a crosslinking monomer unit to form a crosslinking. A base that is not generated or a conjugate base is preferable, and examples thereof include a guanidine compound, an imidazole compound, a quaternary onium salt, a tertiary amine compound, a tertiary phosphine compound, and an alkali metal salt of a weak acid. Examples of the guanidine compound include 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine. Examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri n-butylammonium bromide. Examples of the tertiary amine compound include triethylenediamine and 1,8-diaza-bicyclo [5,4,0] undecene-7. Examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine. Examples of the alkali metal salt of a weak acid include inorganic weak salts such as sodium and potassium phosphates and carbonates, and organic weak salts such as stearates and laurates.

The upper limit of the amount of the crosslinking accelerator used per 100 parts by weight of the acrylic rubber is preferably 20 parts by weight, more preferably 15 parts by weight, particularly preferably 10 parts by weight.
If the amount of the crosslinking accelerator is too large, the crosslinking speed may be too high during crosslinking, the crosslinking accelerator may bloom on the surface of the crosslinked product, or the crosslinked product may be too hard. If the amount of the crosslinking accelerator is too small, the tensile strength of the crosslinked product may be remarkably reduced, or the rate of change in elongation or change in tensile strength after heat load may be too large.

Other Compounds The acrylic rubber composition and the crosslinkable acrylic rubber composition of the present invention may contain , if necessary, a reinforcing material, a filler, an antioxidant, a light stabilizer, a scorch inhibitor, a crosslinking retarder. , Plasticizer,
Additives such as processing aids, lubricants, pressure-sensitive adhesives, lubricants, flame retardants, fungicides, antistatic agents, coloring agents and the like can be further added.

Method for Preparing Crosslinkable Acrylic Rubber Composition The crosslinkable acrylic rubber composition of the present invention comprises:
It can be prepared by blending by an appropriate mixing method such as roll mixing, Banbury mixing, screw mixing, and solution mixing. The mixing order is not particularly limited, but after sufficiently mixing components that are hardly decomposed by heat, components that are easily reacted or decomposed by heat, such as a crosslinking agent and a crosslinking accelerator, may be mixed in as short a time as possible. .

Molding and Crosslinking The molding method and crosslinking method of the crosslinkable acrylic rubber composition of the present invention are not particularly limited. Depending on the molding method, crosslinking method, shape of the crosslinked product, etc., molding and crosslinking may be performed simultaneously or crosslinking may be performed after molding.

The crosslinkable rubber composition of the present invention is crosslinked by heating. The lower limit of the heating temperature is preferably 130 ° C., more preferably 140 ° C., and the upper limit is preferably 220 ° C. It is. If the temperature is too low, a long crosslinking time may be required or the crosslinking density may be low. If the temperature is too high, crosslinking may proceed in a short time, and molding failure may occur.

The crosslinking time is determined by the crosslinking method, crosslinking temperature,
Although it varies depending on the shape of the crosslinked product, a range of 30 seconds or more and 5 hours or less is preferable from the viewpoint of crosslink density and production efficiency.

As the heating method, a method used for crosslinking the rubber, such as press heating, steam heating, oven heating, or hot air heating, may be appropriately selected.

[Crosslinked Product] The crosslinked product of the present invention is obtained by crosslinking the above-mentioned crosslinkable acrylic rubber composition of the present invention,
Excellent tensile strength, small change in tensile strength and tensile stress due to heat load.

The crosslinked product of the present invention takes advantage of its properties to
For example, in addition to transportation equipment such as automobiles, general equipment, etc.,
It is useful as a sealing material, gasket material, cushioning material, protective material, wire covering material, industrial belts, hoses, sheets, rolls, etc. in a wide range of fields such as the electronic field, the electric field, and the electric field. .

[0041]

The present invention will be specifically described below with reference to comparative examples and examples. In addition, each measured value was measured by the following method.

[0042] in accordance with the Mooney viscosity test of the unvulcanized rubber physical testing method of Mooney viscosity JIS K6300, it was measured Mooney viscosity ML _{1 + 4} at a measurement temperature of 100 ° C..

The rubber composition having a tensile strength, elongation and 100% stress was heated at 170 ° C. for 20 minutes by press molding to prepare a sheet having a thickness of 2 mm, and left at 170 ° C. for 4 hours to perform secondary crosslinking. After that, the test piece was punched out using a JIS No. 3 dumbbell test piece, and the JIS K6251 was used.
The tensile strength, elongation, and 100% stress of the crosslinked product were measured under the conditions of a tensile speed of 500 mm / min.

Hardness According to JIS K6253, the hardness of the crosslinked product was measured using a type A durometer.

Example 1 Ethyl acrylate unit content: 53.3% by weight, n-butyl acrylate unit content: 45.0% by weight, mono-n-fumarate
Butyl unit content 1.5% by weight and chloromethylstyrene unit content 0.2% by weight, Mooney viscosity (ML _{1 + 4} , 1
(00 ° C.) 100 parts by weight of 40 acrylic rubber, MA
F carbon black (trade name: Seast 116, manufactured by Tokai Carbon Co., Ltd.) 60 parts by weight, stearic acid 2 parts by weight, lubricant (trade name: Greg G-8205, manufactured by Dainippon Ink and Chemicals, Inc.) 1 part by weight and antioxidant (4, 4 '-(α, α'
2 parts by weight of (dimethylbenzyl) diphenylamine (trade name: Nowguard 445, manufactured by Uniroyal) were kneaded at a set temperature of 50 ° C. using a 0.8 liter Banbury.

The obtained rubber composition, a polyvalent amine crosslinking agent (1.23 parts by weight of 2,2'-bis [4- (4-aminophenoxy) phenyl] propane) and a crosslinking accelerator (di-o-tolyl) 2 parts by weight of guanidine (trade name: Noxeller DT, manufactured by Ouchi Shinko Chemical Co., Ltd.) at a set temperature of 50 ° C.
Kneading was performed using a 6-inch roll.

Using a test piece produced by cross-linking the obtained cross-linkable rubber composition, the cross-linked product had a tensile strength and elongation of 100%.
The stress and hardness were measured, and the tensile strength and the 100% stress after being left at 175 ° C. for 140 hours were measured. Table 1 shows the results.

Example 2 Acrylic rubber was prepared by using an ethyl acrylate unit content of 53.3% by weight, an n-butyl acrylate unit content of 45.0% by weight, a mono-n-butyl fumarate unit content of 1.3% by weight and chloromethylstyrene. Except for changing to an acrylic rubber having a unit content of 0.4% by weight and a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 40, the same treatment as in Example 1 was carried out, and the tensile strength, elongation, 100% stress and Measure hardness and measure at 175 ° C for 14
After standing for 0 hours, the tensile strength and 100% stress were measured. Table 1 shows the results.

Example 3 Acrylic rubber was prepared by using ethyl acrylate unit content of 53.3% by weight, n-butyl acrylate unit content of 45.0% by weight, mono-n-butyl fumarate unit content of 0.9% by weight and chloromethylstyrene. Except for changing to an acrylic rubber having a unit content of 0.8% by weight and Mooney viscosity (ML _{1 + 4} , 100 ° C.) 39, the same treatment as in Example 1 was carried out, and the tensile strength, elongation, 100% stress and Measure hardness and measure at 175 ° C for 14
After standing for 0 hours, the tensile strength and 100% stress were measured. Table 1 shows the results.

Example 4 Acrylic rubber was prepared by using ethyl acrylate unit content of 53.3% by weight, n-butyl acrylate unit content of 45.0% by weight, mono n-butyl fumarate unit content of 0.5% by weight and chloromethylstyrene. Except for changing to an acrylic rubber having a unit content of 1.2% by weight and Mooney viscosity (ML _{1 + 4} , 100 ° C.) 37, the same treatment as in Example 1 was carried out, and the tensile strength, elongation, 100% stress and Measure hardness and measure at 175 ° C for 14
After standing for 0 hours, the tensile strength and 100% stress were measured. Table 1 shows the results.

Comparative Example 1 Acrylic rubber was prepared by adding ethyl acrylate unit content of 53.3% by weight, n-butyl acrylate unit content of 45.0% by weight and mono n-butyl fumarate unit content of 1.7% by weight, Mooney viscosity ( (ML _{1 + 4} , 100 ° C.) Except that the acrylic rubber was changed to 40, the same treatment as in Example 1 was carried out, and the tensile strength, elongation, 100% stress and hardness of the crosslinked product were measured.
The tensile strength and the 100% stress after being left at 140 ° C. for 140 hours were measured. Table 2 shows the results.

Comparative Example 2 An acrylic rubber was prepared by using an ethyl acrylate unit content of 53.3% by weight, an n-butyl acrylate unit content of 45.0% by weight, a chloromethylstyrene unit content of 1.7% by weight, and a Mooney viscosity (ML _{1+). (4} , 100 ° C.) Except that the acrylic rubber was changed to 40, the same treatment as in Example 1 was performed, and the crosslinked product was measured for tensile strength, elongation, 100% stress and hardness, and left at 175 ° C. for 140 hours. After that, the tensile strength and 100% stress were measured, and the tensile strength and 100% stress after being left at 175 ° C. for 140 hours were measured. Table 2 shows the results.

Comparative Example 3 Acrylic rubber was prepared by adding ethyl acrylate unit content of 52.7% by weight, n-butyl acrylate unit content of 45.0% by weight, mono n-butyl fumarate unit content of 1.4% by weight and fumaric acid unit. 0.9% by weight, Mooney viscosity (ML _{1 + 4} ,
(100 ° C.) Except that the acrylic rubber was changed to 39, the same treatment as in Example 1 was carried out.
The stress and hardness were measured, and the tensile strength and the 100% stress after being left at 175 ° C. for 140 hours were measured. Table 2 shows the results.

COMPARATIVE EXAMPLE 4 An acrylic rubber was prepared with an ethyl acrylate unit content of 53.6% by weight, an n-butyl acrylate unit content of 45.0% by weight, a chloromethylstyrene unit content of 1.2% by weight, and a methacrylic acid unit content of 0.1%. 2% by weight, Mooney viscosity (M
(L _{1 + 4} , 100 ° C.) Except that the acrylic rubber was changed to 39, the treatment was carried out in the same manner as in Example 1 to measure the tensile strength, elongation, 100% stress and hardness of the crosslinked product.
After standing for 0 hours, the tensile strength and 100% stress were measured. Table 2 shows the results.

COMPARATIVE EXAMPLE 5 An acrylic rubber was prepared with an ethyl acrylate unit content of 53.6% by weight, an n-butyl acrylate unit content of 45.0% by weight, a chloromethylstyrene unit content of 1.2% by weight, and a methacrylic acid unit content of 0.1%. 2% by weight, Mooney viscosity (M
L _{1 + 4} , 100 ° C.) 39 acrylic rubber (the one used in Comparative Example 4) was used, and the combination of the polyvalent amine crosslinking agent and the crosslinking accelerator was changed to 4 parts by weight of the crosslinking agent sodium stearate, the crosslinking accelerator octadecyl. Trimethylammonium bromide 2 parts by weight and scorch inhibitor diphenylurea 3
Except for changing to a combination of parts by weight, the same treatment as in Example 1 was conducted, and the tensile strength, elongation, 100% stress and hardness of the crosslinked product were measured, and the tensile strength after leaving at 175 ° C. for 140 hours and 100% stress was measured. Table 2 shows the results.

COMPARATIVE EXAMPLE 6 An acrylic rubber was prepared by using ethyl acrylate unit content of 53.3% by weight, n-butyl acrylate unit content of 45.0% by weight, mono n-butyl fumarate unit content of 1.3% by weight and chloromethylstyrene. An acrylic rubber having a unit content of 0.4% by weight and a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 40 (Example 2)
The combination of a polyamine cross-linking agent and a cross-linking accelerator was used instead of the cross-linking agent sodium stearate 4
Except that the combination is 2 parts by weight, 2 parts by weight of octadecyltrimethylammonium bromide and 3 parts by weight of diphenylurea, a scorch inhibitor, the same treatment as in Example 1 is carried out, and the tensile strength, elongation and 100% stress of the crosslinked product are obtained. And the hardness were measured, and the tensile strength and 100% stress after being left at 175 ° C. for 140 hours were measured. Table 2 shows the results.

[0057]

[Table 1]

[0058]

[Table 2]

Comparative Examples 1 and 3 using acrylic rubber containing no halogen-containing unsaturated monomer (b) unit
In this case, the physical properties of the crosslinked product change greatly due to the heat load.

Also in Comparative Examples 2 and 4 using an acrylic rubber containing no ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit, the physical properties of the crosslinked product are greatly changed by heat load.

In Comparative Example 5 using an acrylic rubber containing no ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a crosslinking agent suitable for the same, Comparative Example 5 using the same acrylic rubber was used. In Comparative Example 5, the rate of change in tensile stress of the crosslinked product due to heat load was -9.
%, Which is the same as that of the example, but the change in tensile strength of the crosslinked product due to heat load is large. Also, it has large elongation, small tensile stress, and poor hardness.

An acrylic rubber containing the ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and the halogen-containing unsaturated monomer (b) unit (the same acrylic rubber as in Example 2) was used. In Comparative Example 6 using the same crosslinking agent as Comparative Example 5, the tensile strength and tensile stress of the crosslinked product were small, the rate of change in the tensile stress of the crosslinked product due to heat load was + 40%, and the tensile stress was thermal. Improved by load, but poor in thermal stability. The decrease in tensile strength after heat load is also large. Further, the elongation of the crosslinked product is inferior.

On the other hand, an acrylic rubber containing an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a halogen-containing unsaturated monomer (b) unit was crosslinked with a polyvalent amine crosslinking agent. The crosslinked product of the example has a large tensile strength and a small change in physical properties of the crosslinked product due to heat load.

Specifically, the rate of change in the tensile strength of the crosslinked product due to heat load is smaller than -20% in the comparative example, but is -14% to -20% in the example. The crosslinked product has a small decrease in tensile strength and is excellent in thermal stability.

The rate of change of the tensile stress of the crosslinked product due to the heat load was smaller than -20% in Comparative Examples 1 to 4, whereas it was -6 to -10% in Examples. The crosslinked product has a smaller decrease in tensile stress and is excellent in thermal stability. In addition, Comparative Examples 5 and 6 have the above-mentioned problems other than the decrease in the tensile stress of the crosslinked product.

[0066]

The crosslinked product obtained by crosslinking the crosslinkable rubber composition of the present invention has a large tensile strength and a small change in physical properties of the crosslinked product due to heat load, and is suitable for hose materials, gasket materials, sealing materials and the like. .

Claims (2)

[Claims] 1. 100 parts by weight of an acrylic rubber containing an ethylenically unsaturated polycarboxylic acid incomplete ester monomer (a) unit and a halogen-containing unsaturated monomer (b) unit, and a polyamine crosslinking agent 0 A crosslinkable acrylic rubber composition containing 1 to 20 parts by weight. 2. A crosslinked product obtained by crosslinking the crosslinkable acrylic rubber composition according to claim 1.