JPH09104724A - Production of acrylic elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an acrylic elastomer being capable of being rapidly vulcanized and not needing secondary vulcanization and being capable of giving a vulcanizate excellent in heat resistance and compression set resistance by copolymerizing specified compounds. SOLUTION: Sixty(60) to 99.5 pts.wt. at least one acrylate selected from among 1-8C alkyl acrylates with a 1-8C alkyl and alkoxyalkyl acrylates with a 1-4C alkyl and a 1-4C alkylene is copolymerized with 0.5-10 pts.wt. organic peroxide having a polymerizable unsaturation and 0-30 pts.wt. at least one monomer copolymerizable therewith. Examples of the organic peroxides having a polymerizable unsaturation includes oxides of the formula (wherein R is H, a 1-12C alkyl, an aralkyl or allyloxycarbonyl). More particularly, they are exemplified by allyl t-butyl peroxycarbonate and diallyl peroxydicarbonate.

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 polymerizable unsaturated group-containing peroxide.

[0002]

Acrylic elastomers are generally known as rubbers having excellent heat resistance and oil resistance, and are used for various sealing materials such as O-rings, oil seals, packings, gaskets, etc., which require these performances. ing.
2. Description of the Related Art In recent years, improvement in heat resistance and compression set resistance has been desired as automobiles have higher performance.

[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.

Under these circumstances, the inventors of the present invention have made extensive studies and as a result, the acrylic elastomer copolymerized with the polymerizable unsaturated group-containing peroxide is capable of rapid vulcanization and does not require secondary vulcanization. It has been found that the obtained vulcanized product has excellent heat resistance and compression set resistance.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
(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 polymerizable unsaturated group-containing peroxide, and (c) at least one other copolymerizable with the components (a) and (b). It is achieved by copolymerizing 0 to 30 parts by weight of the above monomer.

Examples of the component (a) monomer used in the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate,
An alkyl acrylate having an alkyl group having 1 to 8 carbon atoms such as octyl acrylate, cyanoethyl acrylate, and the like, and methoxymethyl acrylate,
Examples thereof include alkoxyalkyl acrylates such as methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, etc., in which an alkyl group and an alkylene group each have 1 to 4 carbon atoms.
The amount of these acrylates used is 60 to 99.5 parts by weight, preferably 80 to 97 parts by weight.

The monomer of the component (b) used in the present invention includes [In the formula, R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aralkyl group, and an allyloxycarbonyl group], and a polymerizable unsaturated group-containing peroxide.

Specific examples thereof include t-butyl peroxyallyl carbonate and diallyl peroxy dicarbonate. The amount of these polymerizable unsaturated group-containing peroxides used is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight based on the physical properties of the vulcanizate. The peroxide group of the copolymerized polymerizable unsaturated group-containing peroxide is used for the crosslinking reaction. 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, acrylonitrile, styrene, vinyl acetate, vinylidene chloride, acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1,4-butanediol diacrylate, divinyl. There are benzene, diallyl phthalate and the like, and the amount thereof is 0 to 30 parts by weight. The acrylic elastomer in the present invention can be polymerized by a known polymerization method such as emulsion polymerization, suspension polymerization, solution polymerization and bulk polymerization of the above-mentioned monomer component using a radical initiator which is usually used.

The polymerization temperature is -10 to 100 ° C, preferably 0 to 80 ° C. The acrylic elastomer obtained by polymerization may optionally contain a reinforcing agent, a filler, a plasticizer, a processing aid, an antiaging agent, a crosslinking aid, a pigment and the like. 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 add an organic peroxide having a high degree of risk, which is usually used for peroxide crosslinking. The method for preparing the rubber composition of the present invention is not particularly limited, and the rubber composition can be prepared by adding the above-mentioned components and mixing them with an ordinary kneader such as Banbury or roll.
The rubber composition of the present invention thus obtained is 150
Vulcanization can be performed at a temperature of about 200 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.

[0011]

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 by weight unless otherwise specified.

Examples 1, 2, 3 and Comparative Examples 1, 2 200 parts of water, 2 parts of polyoxyethylene dodecyl ether, 0.8 part of sodium dodecyl sulfate were placed in a separable flask equipped with a stirrer, a thermometer and a reflux condenser. Then, 100 parts of a mixture of each monomer having the composition shown in Table 1 was charged, the internal temperature was kept at 50 ° C., and the atmosphere was sufficiently replaced with nitrogen. Then, 0.2 part of ammonium persulfate and 0.2 part of sodium hydrogen sulfite were added to initiate polymerization. The polymerization temperature is 60 ° C. and the reaction time 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. Polymerization rate is 97%
That was all.

Table 1 An acrylic elastomer and a compounding agent having the compounding recipe shown in Table 2 were mixed by an open roll and then vulcanized to obtain a vulcanized product. Then, various physical properties of each vulcanized product were measured according to JIS K-6301, and the values are shown in Table 3.

Table 2

Table 3

[0016]

According to the present invention, a novel acrylic elastomer having a peroxide group incorporated in a polymer can be obtained by copolymerizing a polymerizable unsaturated group-containing peroxide. The obtained elastomer is capable of rapid vulcanization, does not require secondary vulcanization, and has good 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 polymerizable unsaturated group-containing peroxide, and (c) 0 to at least one other monomer copolymerizable with the components (a) and (b). A method for producing an acrylic elastomer, which comprises copolymerizing 30 parts by weight. 2. The above (b) is The acrylic elastomer according to claim 1, wherein R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aralkyl group, or an allyloxycarbonyl group.