JPH08319320A - Production of acrylic elastomer - Google Patents

Abstract

PURPOSE: To obtain a quickly vulcanizable acrylic elastomer useful as a vulcanized material having excellent heat-resistance and low compression set without using secondary vulcanization treatment by copolymerizing a specific acrylate and a peroxide containing a reactive unsaturated group at specific ratios. CONSTITUTION: The objective acrylic elastomer is produced by copolymerizing (A) 60-99.5 pts.wt. of at least one kind of acrylate selected from between a 1-8C alkyl acrylate and an alkoxyalkyl acrylate having a 1-4C alkyl group and a 1-4C alkylene group, (B) 0.5-10 pts.wt. of a peroxide containing a reactive unsaturated group and preferably expressed by the formula (R<1> is H or methyl; R<2> and R<3> are each a 1-3C alkyl; R<4> is H or a 1-8C alkyl) and (C) 0-30 pts.wt. of at least one kind of other monomer copolymerizable with the components A and B (e.g. acrylonitrile, styrene or vinyl acetate).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an acrylic elastomer. More specifically, it relates to a method for producing a novel acrylic elastomer obtained by copolymerizing a peroxide containing a reactive unsaturated group.

[0002]

2. Description of the Related Art Conventionally, acrylic elastomers are generally known as rubbers having excellent heat resistance and oil resistance, and they are used for various seals, gasket materials and the like which are required to have these properties. In recent years, as automobiles have become more sophisticated, heat resistance,
Improvement of compression set resistance is desired.

[0003]

The acrylic elastomer is copolymerized with a crosslinking site-donating monomer, and a crosslinking agent suitable for the crosslinking site is selected for crosslinking. An active halogen group, an epoxy group, a carboxyl group, a vinyl group or the like is used as a crosslinking site. They are,
The vulcanization reaction is not always fast in order to balance the vulcanization speed and the scorch property of the fabric, and secondary vulcanization is currently performed to stabilize the physical properties.

As a result of intensive investigations by the present inventors, the acrylic elastomer copolymerized with a reactive unsaturated group-containing peroxide is capable of rapid vulcanization and does not require secondary vulcanization. It was found that the sulfide has excellent heat resistance and compression set resistance.

[0005]

The object of the present invention is to:
(A) at least one acrylate selected from the group consisting of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and an alkoxyalkyl acrylate having an alkyl group and an alkylene group each having 1 to 4 carbon atoms 60 to 99.5 parts by weight, (b) 0.5 to 10 parts by weight of a reactive unsaturated group-containing peroxide, and (c) at least one other copolymerizable with the above-mentioned components (a) and (b). This is accomplished by copolymerizing 0 to 30 parts by weight of the monomer.

The monomer of the component (a) used in the present invention has a carbon number of 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate and octyl acrylate. And an alkoxyalkyl acrylate having an alkyl group and an alkylene group each having 1 to 4 carbon atoms, such as methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, and the like. The amount of these acrylates used is 60 to 99.5 parts by weight, preferably 80 to 97 parts by weight.

As the monomer of the component (b) used in the present invention, there is a reactive unsaturated group-containing peroxide represented by Chemical formula 1, and the amount thereof is 0.5 to 10 parts by weight, preferably Is 1 to 5 parts by weight due to the physical properties of the vulcanized product. Specific examples of the reactive unsaturated group-containing peroxide represented by the general formula: Chemical formula 1 are 3- (2-t-butylperoxypropyl) -styrene and 1- (2-t-butyl). Peroxyisopropyl) -3-isopropenylbenzene. The monomer of the component (c) used in the present invention is optionally used in order to improve the mechanical properties, oil resistance, cold resistance and the like of the resulting acrylic elastomer. Specifically, there are acrylonitrile, styrene, vinyl acetate, vinylidene chloride, acrylic acid, ethyl methacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, etc., and the amount used is 0 to 30 parts by weight. is there.

The acrylic elastomer in the present invention is
The monomer component can be polymerized by a well-known polymerization method such as emulsion polymerization, suspension polymerization, solution polymerization and bulk polymerization using a commonly used radical initiator. Polymerization temperature is -10 to 100
C., preferably 0 to 80.degree. Acrylic elastomer obtained by polymerization, if necessary, a reinforcing agent, a filler,
A plasticizer, a processing aid, an antiaging agent, a crosslinking aid, a pigment and the like can be optionally mixed. In the elastomer of the present invention, since the peroxide group of the polymer is subjected to the crosslinking reaction,
It is not necessary to incorporate high-risk organic peroxides that are commonly used for peroxide crosslinking.

The method for preparing the rubber composition of the present invention is not particularly limited, and it can be prepared by adding the above-mentioned components and mixing them by a usual kneading machine such as Banbury or roll. The rubber composition of the present invention thus obtained can be vulcanized at a temperature of about 150 ° C. to 200 ° C. for about 2 to 20 minutes. The composition obtained from the acrylic elastomer of the present invention does not require secondary vulcanization which is carried out in order to stabilize the physical properties of the vulcanizate of ordinary acrylic rubber compositions.

[0010]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. Parts are based on weight unless otherwise specified. Examples 1 and 2 and Comparative Examples 1 and 2 200 parts of water, 2 parts of polyoxyethylene dodecyl ether, 0.8 part of sodium dodecylsulfate, and 0.8 part of a separable flask equipped with a stirrer, a thermometer, and a reflux condenser, and described in Table 1. 100 parts of a mixture of each monomer having the above composition was charged, and the internal temperature was kept at 50 ° C., and the atmosphere was sufficiently replaced with nitrogen. Then
Polymerization was initiated by adding 0.2 part of ammonium persulfate and 0.2 part of sodium hydrogen sulfite. Polymerization temperature is 60
The reaction time at 1.5 ° C. is 1.5 hours. After the completion of the polymerization, the polymerization product was salted out, washed thoroughly with water, and dried to obtain the target acrylic elastomer. The polymerization rates were all 97% or more.

[0011]

[Table 1]

The acrylic elastomer and the compounding agent having the compounding formulations shown in Table 2 were mixed by an open roll and then vulcanized to obtain a vulcanized product. Then, various physical properties of each vulcanizate were measured according to JIS K-6301, and the values are shown in Table 3.

[Table 2]

[0013]

[Table 3]

[0014]

According to the present invention, a novel acrylic elastomer having a peroxy group incorporated in a polymer can be obtained by copolymerizing a reactive unsaturated group-containing peroxide. The obtained elastomer can be rapidly vulcanized, does not require secondary vulcanization, and has excellent heat resistance and compression set resistance.

Claims (2)

[Claims] 1. At least one selected from the group consisting of (a) an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and an alkoxyalkyl acrylate having an alkyl group and an alkylene group each having 1 to 4 carbon atoms. 60 to 99.5 parts by weight of one acrylate,
(B) 0.5 to 10 parts by weight of a reactive unsaturated group-containing peroxide, and (c) at least one other monomer 0 to 30 copolymerizable with the above components (a) and (b). A method for producing an acrylic elastomer, which comprises copolymerizing parts by weight. 2. A reactive unsaturated group-containing peroxide is represented by: [Wherein R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ represent an alkyl group having 1 to ³ carbon atoms, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms] 1. The acrylic elastomer according to 1.