JP2001240623A - Acrylic rubber, crosslinkable acrylic rubber composition and crosslinked product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an acrylic rubber cross-linked product having excellent heat, cold and oil resistances with a large tensile strength and little change in tensile strength and elongation under a heat load. SOLUTION: This acrylic rubber cross-linked product is obtained by crosslinking an acrylic rubber obtained by copolymerizing 30-97.9 wt.% of a monomer (1) expressed by the formula: CH2=CH-COO-R1 (R1 expresses a 1-5C alkyl) with 1-30 wt.% of a monomer (2) expressed by the formula: CH2=CR2- COO-R3 (R2 expresses H or CH3; R3 expresses a 6-12C alkyl, cycloalkyl or aryl), 1-30 wt.% of a monomer (3) expressed by the formula: CH2=CR4- COO-[-(CH2)q-COO-]r-R5 (R4 expresses H or CH3; R5 expresses H or a 1-12C alkyl; q expresses 4-12 integer; r expresses 1-20 integer) and 0.1-10 wt.% of a crosslinking monomer (4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cold-resistant acrylic rubber and a crosslinkable acrylic rubber composition, and a crosslinked product thereof.

[0002]

2. Description of the Related Art Acrylic rubber is excellent in heat resistance and oil resistance, and is widely used in fields related to automobiles. However, furthermore, cold resistance and heat resistance stability have been strongly demanded, and improvement research is being conducted.

As an acrylic rubber excellent in heat resistance, cold resistance, oil resistance, etc., an acrylic rubber copolymerized with a lactone-added acrylate is known (JP-A-63-264).
612, JP-A-2-209907, etc.).
However, this acrylic rubber has a problem that its tensile strength is inferior and that the strength is greatly reduced by heat load.

An acrylic rubber copolymerized with an ethylene oxide-added acrylate is known to be excellent in oil resistance and cold resistance (Japanese Patent Laid-Open No. 5-26283).
No. 0) has a problem that the elongation greatly changes due to the heat load, and the rubber elasticity is lost.

Further, it is known that a vinyl addition polymer of a Michael adduct of acrylic acid is excellent in oil resistance (Japanese Patent Application Laid-Open No. 58-104908).
This also has a problem that the elongation is remarkably reduced by the heat load, and the rubber elasticity is lost.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide excellent heat resistance, cold resistance, oil resistance, high tensile strength,
An object of the present invention is to provide an acrylic rubber crosslinked product having a small change in tensile strength and change in elongation due to a heat load.

[0007] To achieve the above object, the present inventors have
As a result of intensive studies, they have found that the above object can be achieved by crosslinking an acrylic rubber copolymerized with a specific monomer, and have completed the present invention.

[0008]

According to the present invention, there is provided:
If CH_Two= CH-COO-R¹(R¹Has 1 to 5 carbon atoms
Monomer (1) unit represented by the following formula:
97.9% by weight, CH _Two= CR^Two-COO-R^Three(R^TwoIs H
Or CH_Three, R^ThreeIs an alkyl group having 6 to 12 carbon atoms,
Represented by a loalkyl or aryl group)
Body (2) unit 1 to 30% by weight, CH_Two= CR^Four-COO-
[-(CH_Two)_q-COO-]_r-R^Five(R ^FourIs H or C
H_Three, R^FiveIs H or an alkyl group having 1 to 12 carbon atoms, and q is
An integer of 4 to 12, r represents an integer of 1 to 20)
1 to 30% by weight of a monomer (3) unit and a crosslinkable monomer
(4) Acrylic containing 0.1 to 10% by weight of unit
And a crosslinking agent 0.1 to 100 parts by weight of the acrylic rubber.
Crosslinkable acrylic rubber composition containing 10 parts by weight and
A crosslinked product obtained by crosslinking the crosslinkable acrylic rubber is provided.
You.

[Acrylic Rubber] The acrylic rubber of the present invention comprises 30 units of monomer (1) represented by CH ₂ ＣＨCH—COO—R ¹ (R ¹ represents an alkyl group having 1 to 5 carbon atoms). ~
97.9 ^{_{wt%, CH 2 = CR 2 -COO}} -R 3 (R 2 is H
Or CH ₃ and R ³ each represent an alkyl group having 6 to 12 carbon atoms, a cycloalkyl group or an aryl group), 1 to 30% by weight of a unit (2), CH ₂ ＣＲCR ⁴ —COO—
[— (CH ₂ ) _q —COO—] _r —R ⁵ (q is an integer of 4 to 12, r is an integer of 2 to 20, R ⁴ is H or CH ₃ , R ⁵ is hydrogen or a carbon number of 1 to 12. And q is 4 to 12
And r represents an integer of 1 to 20), wherein 1 to 30% by weight of a monomer (3) unit and 0.1 to 10% by weight of a crosslinkable monomer (4) unit are represented. It is.

Monomer (1) Monomer (1) is an alkyl acrylate monomer represented by CH ₂ ＣＨCH—COO—R ¹ (R ¹ represents an alkyl group having 1 to 5 carbon atoms). It is preferred that R ¹ has ¹ to 4 carbon atoms. If the number of carbon atoms is too large, the tensile strength of the rubber may decrease. Specifically, methyl acrylate,
Examples include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, and the like.

The lower limit of the monomer (1) unit content in the acrylic rubber of the present invention is 30% by weight, preferably 55% by weight, particularly preferably 67% by weight, and the upper limit is 97.
It is 9% by weight, preferably 93.7% by weight, particularly preferably 89.5% by weight. If the monomer (1) unit content is too small, the oil resistance is poor, and if it is too large, the cold resistance is poor.

[0012]Monomer (2) The monomer (2) is CH_Two= CR^Two-COO-R^Three(R^TwoIs H
Or CH_Three, R^ThreeIs an alkyl group having 6 to 12 carbon atoms,
Represents an alkyl group or an aryl group)
It is. Specifically, n-hexyl acrylate, acrylic
2-ethylhexyl acrylate, n-nonyl acrylate, etc.
R^TwoIs H and R^ThreeIs an alkyl group; acrylic acid
Rohexyl, 4-methylcyclohexyl acrylate
Which R²Is H and R³Is a cycloalkyl group;
Phenyl acrylate, acrylic acid-p-tolyl, acrylic
R such as acid-β-naphthyl^TwoIs H and R^ThreeIs an aryl group
N-hexyl methacrylate, methacrylic acid-2
R such as -ethylhexyl and n-nonyl methacrylate^Two
Is CH_ThreeIn R^ThreeIs an alkyl group; methacrylic acid
Clohexyl, 3-methylcyclohexyl methacrylate
R such as²Is CH _ThreeIn R³Is a cycloalkyl group
What: phenyl methacrylate, methacrylic acid-o-tri
R, such as α-naphthyl methacrylate^TwoIs CH_ThreeIn R
^ThreeIs an aryl group; and the like.

The lower limit of the monomer (2) unit content in the acrylic rubber of the present invention is preferably 1% by weight, more preferably 3% by weight, particularly preferably 5% by weight, and the upper limit is:
Preferably it is 30% by weight, more preferably 20% by weight, particularly preferably 15% by weight. If the unit content of the monomer (2) is too small, the strength may be significantly reduced by heat load, and if it is too large, the oil resistance may be poor.

Monomer (3) Monomer (3) is represented by CH ₂ ＣＲCR ⁴ —COO — [— (C
H ₂ ) _q -COO-] _r -R ⁵ (R ⁴ is H or CH ₃ , R ⁵
Is H or an alkyl group having 1 to 12 carbon atoms, and q is 4 to 12
And r represents an integer of 1 to 20), and specifically, ethyl (6-acryloxy) hexanoate, n-butyl (6-acryloxy) hexanoate, α-ethyl-ω- Acryloxy poly [oxy (1
-Oxopentamethylene)], α-n-butyl-ω-acryloxypoly [oxy (1-oxopentamethylene)], α-hydro-ω-acryloxypoly [oxy (1-oxohexamethylene)], α -Methyl-ω-acryloxypoly [oxy (1-oxohexamethylene)], α-ethyl-ω-acryloxypoly [oxy (1-oxohexamethylene)], α-n-butyl-ω
-Acryloxypoly [oxy (1-oxohexamethylene)], α-ethyl-ω-acryloxypoly [oxy (1-oxodecamethylene)], α-n-butyl-ω-
Akurirokishipori [oxy (1-oxo-decamethylene) R ⁴ is an H, such as; alpha-ethyl -ω- methacryloxypolyethoxyphenyl [oxy (1-oxo-decamethylene)] alpha-ethyl -ω- methacryloxy Those in which R ⁴ is CH ₃ , such as poly [oxy (1-oxopentamethylene)]; These may be used alone or in combination of two or more.

The monomer (3) is preferably one in which R ⁴ is H, which is excellent in the balance among oil resistance, cold resistance and tensile strength, more preferably one in which R ⁴ is H and r is an integer of 1 to 5, α-methyl-ω-acryloxypoly [oxy (1-oxohexamethylene)], α-ethyl-ω-acryloxypoly [oxy (1-oxohexamethylene)], α-n-butyl-ω-acryloxy Poly [oxy (1-oxohexamethylene)] and the like are particularly preferred.

The lower limit of the monomer (3) unit content in the acrylic rubber of the present invention is preferably 1% by weight, more preferably 3% by weight, particularly preferably 5% by weight, and the upper limit is
Preferably it is 30% by weight, more preferably 20% by weight, particularly preferably 15% by weight. When the monomer (3) unit content is too small, oil resistance or cold resistance may be poor, and when too large, the strength is poor.

Crosslinkable monomer (4) The crosslinkable monomer (4) is a monomer for introducing a crosslinking point into the acrylic rubber, and is copolymerizable with the monomers (1) to (3). Is not particularly limited as long as the resulting acrylic rubber can be crosslinked. For example, there are carboxylic acid-based crosslinkable monomers, halogen-based crosslinkable monomers, epoxy-based crosslinkable monomers, diene-based crosslinkable monomers, and the like.

The carboxylic acid-based crosslinkable monomer is a monomer that can be copolymerized with acrylates and contains a carboxyl group. Examples of the carboxyl group-containing monomer include carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; monomethyl itaconate;
In addition to carboxylic acid ester monomers such as monoethyl itaconate, mono-n-butyl itaconate, monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monomethyl fumarate, monoethyl fumarate, and mono-n-butyl fumarate Carboxylic acid anhydride monomers such as maleic anhydride containing a carboxylic acid anhydride group,
Preferred are carboxylic acid ester monomers, more preferred are butenedioic acid monoester monomers such as fumaric acid monoester and maleic acid monoester, and particularly preferred are fumaric acid monoalkyl ester monomers.

The halogen-based crosslinkable monomer is a monomer containing a halogen atom. For example, unsaturated alcohol esters of halogen-containing saturated carboxylic acids such as vinyl chloroacetate and allyl chloroacetate; unsaturated ethers containing halogen such as chloromethyl vinyl ether and 2-chloroethyl vinyl ether; p-chlorostyrene, vinylbenzyl chloride and the like And halogen-containing aromatic vinyl compounds.

The epoxy-based crosslinkable monomer is a monomer copolymerizable with acrylates and containing an epoxy group. Examples of the epoxy-based crosslinkable monomer include unsaturated glycidyl esters such as glycidyl acrylate and glycidyl methacrylate; and unsaturated glycidyl ethers such as vinyl glycidyl ether and allyl glycidyl ether.

The diene-based crosslinkable monomer is a monomer which can be copolymerized with acrylates and has a diene structure. Examples of diene-containing monomers include conjugated diene-based monomers such as butadiene, isoprene and piperylene, and non-conjugated diene-based monomers such as dicyclopentadiene, norbornene, ethylidene norbornene, vinylidene norbornene, cyclohexenyl acrylate and cyclohexenyl methacrylate. And the like.

The lower limit of the content of the crosslinkable monomer (4) in the acrylic rubber of the present invention is 0.1% by weight, preferably 0.3% by weight, particularly preferably 0.5% by weight. The upper limit is 10% by weight, preferably 5% by weight, particularly preferably 3% by weight. If the unit content of the crosslinking monomer (4) is too small, crosslinking is not sufficiently performed, and if it is too large, elongation is reduced.

Other Monomers The acrylic rubber of the present invention is obtained by copolymerizing a monomer copolymerizable therewith, in addition to the above-mentioned monomers, as long as the effects of the present invention are not impaired. Is also good.

Other copolymerizable monomers include methoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 4-methoxybutyl acrylate, and 4-ethoxybutyl acrylate. Acid alkoxyalkyl ester monomers; α, β-unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; α-olefins such as ethylene and propylene; vinyl monomers such as vinyl chloride styrene and α-methyl styrene Body: alkyl group such as furfuryl ester of acrylic acid, acrylamide, methacrylamide, cycloalkyl group, [oxy (1-oxoalkylene)]
Acrylic acid-derived monomer or methacrylic acid-derived monomer substituted with a group other than a group;
Examples include polyfunctional monomers such as divinylbenzene, ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, and propylene glycol dimethacrylate.

Among them, alkoxyalkyl acrylate is preferable, and CH ₂ ＣＨCH—COO—R ⁶
Those represented by —OR ⁷ (R ⁶ represents an alkylene group having 1 to 5 carbon atoms, and R ⁷ represents an alkyl group having 1 to 5 carbon atoms) are preferable, and 2-methoxyethyl acrylate is particularly preferable.

When these monomers are copolymerized, the content of these monomer units in the acrylic rubber is preferably at most 30% by weight, more preferably at most 20% by weight, particularly preferably at most 10% by weight. is there. If the amount is too large, the effect of the present invention may not be obtained.

Mooney viscosity The lower limit of the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the acrylic rubber is preferably 5, more preferably 10, and particularly preferably 15, 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.

Crosslinking agent The crosslinking agent may be selected depending on the type of the crosslinking monomer (4), and is not particularly limited as long as the acrylic rubber of the present invention can be crosslinked.

When the crosslinking monomer (4) is a carboxylic acid crosslinking monomer, hexamethylene diamine, hexamethylene diamine carbamate, N,
Aliphatic diamine compounds such as N'-dicinnamylidene-1,6-hexanediamine;4,4'-diaminodiphenyl ether, 4,4 '-(m-phenylenediisopropylidene) dianiline, 4,4'-(p-phenyldiamine Diisopropylidene) dianiline, 2,2′-bis [4-
It is preferable to use an aromatic diamine compound such as (4-aminophenoxy) phenyl] propane;

When the crosslinkable monomer (4) is a halogen-based crosslinkable monomer, sulfur or 1,3,
It is preferable to use a triazine thiol compound such as 5-triazine thiol or a derivative thereof. When the crosslinkable monomer (4) is an epoxy-based crosslinkable monomer,
Organic ammonium carboxylate such as ammonium benzoate, ammonium adipate and the like are used.

When the crosslinkable monomer (4) is a diene-based crosslinkable monomer, an organic peroxide having an —O—O— structure in the molecule, for example, dicumyl peroxide is used as a crosslinking agent. , Di-t-butyl peroxide, t-butyl cumyl peroxide, benzoyl peroxide, 2,4
-Dichlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-
3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate , 1,3-di (t-butylperoxyisopropyl) benzene and the like.

The lower limit of the compounding amount of the crosslinking agent is as follows.
0.1 part by weight, preferably 0.2 part by weight, particularly preferably 0.3 part by weight, per 100 parts by weight, and the upper limit is 1 part by weight.
0 parts by weight, preferably 7 parts by weight, particularly preferably 5 parts by weight. If the compounding amount of the crosslinking agent is too small, crosslinking becomes insufficient, and the shape of the molded rubber after crosslinking cannot be maintained,
If it is too much, it is too hard and impairs rubber elasticity.

Crosslinking Accelerator In the present invention, a crosslinking accelerator can be used together with a crosslinking agent, if necessary. The crosslinking accelerator is not particularly limited as long as it promotes crosslinking in combination with the crosslinking agent.

The crosslinking accelerator used in combination with the diamine compound has a base dissociation constant of 10 at 25 ° C. in water.
^-12 to 10 ^{+ 6} , preferably a base or a conjugate base which does not substantially react with the crosslinkable monomer unit to form a crosslink, a guanidine accelerator, a quaternary onium salt accelerator, Tertiary amine accelerator, heterocyclic tertiary amine accelerator, tertiary phosphine accelerator, alkali metal salt or alkali metal hydroxide of inorganic weak acid, alkali metal salt of organic weak acid, alkali metal alkoxy Rate or alkali metal phenolate. Guanidine-based accelerators include 1,3-diphenylguanidine, di-o
-Tolylguanidine and the like. Examples of the quaternary onium salt accelerator include tetrabutylammonium bromide and tetrabutylammonium chloride. Hexamethyltriethylenetetramine as a tertiary amine accelerator, imidazole, 2-methylimidazole,
-Isopropylimidazole, 1,8-diaza-bicyclo [5,4,0] undecene-7 and the like. Examples of the tertiary phosphine accelerator include triphenylphosphine and tri (methylphenyl) phosphine. Examples of the alkali metal salts or alkali metal hydroxides of inorganic weak acids include sodium, potassium or lithium hydroxides, phosphates, carbonates, bicarbonates and the like. As an alkali metal salt of an organic weak acid, an alkali metal alkoxylate or an alkali metal phenolate,
Examples include sodium methoxide, potassium stearate, sodium isopropoxide, potassium isopropoxide, potassium laurate, sodium phenoxide, potassium phenoxide, potassium benzoate, and the like.

Examples of the crosslinking accelerator used in combination with sulfur include an alkali metal carboxylate and a thiazole compound. As the alkali metal carboxylate,
Sodium stearate, potassium stearate, sodium laurate, potassium laurate, and the like, and examples of the thiazole compound include mercaptobenzothiazole, dibenzothiazyl disulfide, and the like.

Examples of the crosslinking accelerator used in combination with the triazine thiol compound include a thiuram-based accelerator and a dithiocarbamate-based accelerator. As a thiuram-based accelerator, tetraethylthiuram disulfide,
Tetrabutylthiuram disulfide and the like can be mentioned.
The dithiocarbamate-based accelerator is selected from zinc salts, copper salts, iron salts and tellurium salts of dithiocarbamic acids, preferably zinc salts, and includes zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate and the like.

The upper limit of the amount of the crosslinking accelerator used per 100 parts by weight of the acrylic rubber is preferably 15 parts by weight, more preferably 12 parts by weight, and particularly preferably 10 parts by weight. If the amount of the crosslinking accelerator is too large, the crosslinking speed during crosslinking becomes too fast, the crosslinking accelerator blooms on the surface of the crosslinked product, or the crosslinked product becomes too hard.

Other Compounds 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 retardant, as long as its properties are not impaired. Agent, 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.

The crosslinkable acrylic rubber composition of the present invention can be prepared by blending the above components 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 react with heat or are easily decomposed, such as a cross-linking agent and a cross-linking accelerator, should be mixed in as short a time as possible. Good.

[Crosslinked Product] The crosslinked product of the present invention is obtained by crosslinking the above crosslinkable acrylic rubber composition.

Molding and Crosslinking The molding method and crosslinking method of the crosslinkable acrylic rubber composition are not particularly limited. Molding method, cross-linking method, if necessary, such as the shape of the cross-linked product, molding or cross-linking at the same time,
What is necessary is just to bridge | crosslink after shaping | molding.

The lower limit of the heating temperature for crosslinking the crosslinkable acrylic rubber composition is preferably 130 ° C., more preferably 140 ° C., and the upper limit is preferably 220 ° C. 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 depends on the shape and the like, a range of 30 seconds or more and 5 hours or less is preferable from the viewpoint of the crosslinking density and the production efficiency.

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

Use The crosslinked product of the present invention is obtained by crosslinking the crosslinkable acrylic rubber composition of the present invention described above, and is excellent in cold resistance, oil resistance and tensile strength, and depends on the thermal load of tensile strength and elongation. The change is small.

Taking advantage of its properties, for example, in a wide range of fields such as electronic equipment, electric equipment, electric equipment, etc., in addition to transportation machines such as automobiles, general equipment, etc., sealing materials, gasket materials, cushioning materials, protective materials, electric wires, etc. It is useful as a material for coating materials, industrial belts, hoses, sheets, rolls, and the like.

[0047]

EXAMPLES 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.

[0048] 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} of acrylic rubber in a measurement temperature 100 ° C..

The tensile strength and the stretched rubber composition were heated by press molding at 170 ° C. for 20 minutes to form a sheet having a thickness of 2 mm, left at 170 ° C. for 4 hours, and subjected to secondary crosslinking. No. dumbbell test piece and JIS K6251
The tensile strength and elongation of the crosslinked product were measured under the conditions of a tensile speed of 500 mm / min.

Volume change rate in immersion test in oil A sheet was prepared in the same manner as the test piece for tensile strength and elongation, and after secondary cross-linking, punched into a 50 mm x 20 mm rectangle, and this was used as a test piece according to JIS K6258. No. of 150 ° C. It was immersed in three oils (containing 40% or more of naphthene system and 45% or less of paraffin system) for 70 hours, and the volume change rate was measured.

[0051] to produce a Gehman like the test piece T ₁₀ tensile strength and for elongation at torsion test sheet, after secondary crosslinking, punched into a rectangle of 40 mm × 3 mm, cold JIS K6261 twisting it as a test piece According to the test, the temperature at which the specific modulus RM became 10 (Geman T ₁₀ ) was measured.

Example 1 Acrylic rubber (ethyl acrylate unit content 6.5 wt.
%, N-butyl acrylate unit content 74% by weight,
2-ethylhexyl luate unit content 8% by weight, α-ethyl
-Ω-acryloxypoly [oxy (1-oxohexame
(Tylene)] (CH _Two= CHCO [O (CH_Two)_FiveCO]_n
OCH_TwoCH_Three) (N is 2.8 in number average) Unit content 10 weight
%, Mono n-butyl fumarate unit content 1.5% by weight,
Mooney viscosity (ML_{1 + 4}, 100 ° C) 25.2) 100
Parts by weight, MAF carbon black (trade name: Seast 11)
6, Tokai Carbon Co.) 60 parts by weight, stearic acid double
Amount, lubricant (trade name Greg G-8205, Dainippon
1 part by weight, an antioxidant (4,4'-
(Α, α'-dimethylbenzyl) diphenylamine, quotient
Product name Nowguard 445, manufactured by Uniroyal) 2 parts by weight
At a set temperature of 50 ° C, using a 0.8 liter Banbury
Kneaded.

To the obtained rubber composition, 0.5 parts by weight of a crosslinking agent hexamethylenediamine carbamate and a crosslinking accelerator (di-o-tolylguanidine, trade name Noxeller D)
T, Ouchi Shinko Chemical Co., Ltd.) 2 parts by weight, set temperature 50
At 6 ° C., the mixture was added using a 6-inch roll and kneaded.

[0054] The crosslinked product of the resulting crosslinkable rubber composition, tensile strength, elongation, measured T ₁₀ in the volume change rate and the Gehman torsion test in oil immersion test, 17
Tensile strength and elongation after standing at 5 ° C. for 500 hours were measured. Table 1 shows the results.

Comparative Example 1 An acrylic rubber was used in an ethyl acrylate unit content of 6.5 wt.
%, N-butyl acrylate unit content 74% by weight, α-d
Cyl-ω-acryloxypoly [oxy (1-oxohexene)
Samethylene)] (CH_Two= CHCO [O (CH_Two)_FiveC
O]_nOCH_TwoCH _Three) (N is 2.8 in number average) unit content
18% by weight, unit content of mono-n-butyl fumarate 1.5 times
%, Mooney viscosity (ML_{1 + 4}, 100 ° C) 24.6
Except for changing to acrylic rubber,
Prepare a bridge rubber composition and check the properties of the crosslinked product.
It was measured. Table 1 shows the results.

Comparative Example 2 An acrylic rubber was prepared by mixing ethyl acrylate unit content 6.5% by weight, n-butyl acrylate unit content 74% by weight, α-ethyl-ω-acryloxy poly (oxyethylene) (CH
_{2 = CHCOO [(CH 2)} 2 O] n OCH 2 CH 3) (n
Is a number average of 2.0) unit content 18% by weight, mono-n-butyl fumarate unit content 1.5% by weight, Mooney viscosity (ML
_{1 + 4} , 100 ° C.) A crosslinkable rubber composition was prepared in the same manner as in Example 1 except that the acrylic rubber was changed to 22.9.
The physical properties of the crosslinked product were measured. Table 1 shows the results.

Comparative Example 3 An acrylic rubber was prepared by mixing ethyl acrylate unit content 6.5% by weight, n-butyl acrylate unit content 74% by weight, α-ethyl-ω-acryloxypoly [oxy (1-oxotrimethylene) (CH ₂ ＣＨCHCOO [(CH ₂ ) ₂ COO]
_n CH ₂ CH _{3) (n} is the number average 2.8) unit content 18 wt%, 1.5 wt% content of fumaric acid mono-n- butyl units,
A crosslinkable rubber composition was prepared in the same manner as in Example 1 except that acrylic rubber having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 25.6 was used, and the physical properties of the crosslinked product were measured. Table 1 shows the results.

[0058]

[Table 1]

The crosslinked product of Comparative Example 1 using an acrylic rubber containing no monomer (2) unit has a large decrease in tensile strength due to heat load.

The crosslinked product of Comparative Example 2 using an acrylic rubber copolymerized with a lactone addition type acrylate, which corresponds to the prior art (JP-A-63-264612, JP-A-2-209907, etc.), is oil-resistant. The change in tensile strength due to heat load is small, but the change in elongation is large and rubber elasticity is lost.

A vinyl addition polymer of a Michael adduct of acrylic acid (which does not contain a monomer (2) unit or a monomer (3) unit) which corresponds to the prior art (JP-A-58-104908, etc.) Acrylic rubber, CH ₂ ＣＨCHC
OO [(CH ₂ ) ₂ COO] _n CH ₂ CH ₃ is a monomer (3)
When applied to the equation representing, q = 2, and q is 4 to 12
Does not correspond to the monomer (3). Comparative Example 3)
Is excellent in oil resistance, but inferior in cold resistance, and has a large change in tensile strength and elongation due to heat load.

On the other hand, the crosslinked product of Example 1 using the acrylic rubber of the present invention containing the units of the monomers (1) to (4) is excellent in oil resistance, cold resistance, tensile strength and elongation. ,
Further, changes in tensile strength and elongation due to heat load are small.

[0063]

The crosslinked product of the rubber composition of the present invention is excellent in oil resistance, cold resistance, heat aging resistance, tensile strength, etc., and particularly, the tensile strength change rate and elongation change rate in a high temperature environment. small.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C08F 220/12 (C08F 220/12 220: 28) 220: 28) F-term (Reference) 4F070 AA32 AC45 AC46 AE08 GA06 GC02 4J002 BG041 BG071 DA046 EG026 EK016 EK036 EK046 EK056 EK066 EN036 EN076 EV086 FD146 GJ02 GM01 GN00 GQ00 GQ01 4J008 AL03 AB10 BA04 BA05 BA06 BA07 BA09 BA10 BA17 CD18 A100 AG AR11S AR22S AS02S AS03S AS15S AS17S BA20R BA21R BB01S BC04Q BC43Q BC49Q BC54S CA03 CA06 HA53 HC27 HC36 HC46 HC70 JA00 JA28 JA43

Claims (3)

[Claims] A monomer (1) represented by CH ₂ ＣＨCH—COO—R ¹ (R ¹ represents an alkyl group having 1 to 5 carbon atoms)
Unit 30 to 97.9 ^{_{wt%, CH 2 = CR 2 -COO}} -R
³ (R ² represents H or CH ₃ , R ³ represents an alkyl group having 6 to 12 carbon atoms, a cycloalkyl group or an aryl group) 1 to 30% by weight of a unit (2), CH ₂ = CR ⁴
_{-COO - [- (CH 2)} q -COO-] r -R 5 (R 4 is H or _CH 3, R ⁵ is H or an alkyl group having 1 to 12 carbon atoms, q is 4 to 12 integer, r Is an integer of 1 to 20). An acrylic rubber containing 1 to 30% by weight of a monomer (3) unit and 0.1 to 10% by weight of a crosslinkable monomer (4) unit. 2. A crosslinkable acrylic rubber composition containing 0.1 to 10 parts by weight of a crosslinking agent based on 100 parts by weight of the acrylic rubber according to claim 1. 3. A crosslinked product obtained by crosslinking the crosslinkable acrylic rubber according to claim 2.