JPH09132604A - Production of acrylic elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a novel acrylic elastomer containing a polymerizable- unsaturation-containing peroxide as a comonomer. SOLUTION: This acrylic elastomer is produced by copolymerizing 60-99.5wt.% at least one acrylate selected from the group consisting of alkyl acrylates with a 1-8C alkyl and alkoxyalkyl acrylates with a 1-4C alkyl and a 1-4C alkylene with 0.5-10 pts.wt. polymerizable-unsaturation-containing peroxide, 0.5-10 pts.wt. diene compound and 0-30 pts.wt. at least another monomer copolymerizable therewith.

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.
BACKGROUND ART In recent years, as the performance of automobiles has increased, it has been desired to significantly improve heat resistance and compression set resistance.

[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, an acrylic elastomer obtained by copolymerizing a polymerizable unsaturated group-containing peroxide and a diene compound can be rapidly vulcanized and does not require secondary vulcanization. It was found that the obtained vulcanizates have 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) polymerizable unsaturated group-containing peroxide 0.5 to 10 parts by weight, (c) diene compound 0.5 to 10 parts by weight, and (d) the above (a),
It is achieved by copolymerizing 0 to 30 parts by weight of at least one other monomer copolymerizable with the components (b) and (c).

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 component (b) used in the present invention is

Embedded image [In the formula of Chemical formula 2, R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aralkyl group, or an allyloxycarbonyl group], or 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.

Examples of the monomer of the component (c) used in the present invention include butadiene, isoprene, dicyclopentadiene, vinyl acrylate, allyl methacrylate, tetrahydrobenzyl acrylate, dicyclopentenyl acrylate, ethylidene norbornene, vinylidene norbornene and the like. To be The amount of these diene compounds used is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight based on the physical properties of the vulcanized product. By using these diene compounds as the crosslinking site-donating monomer, it is possible to obtain sufficiently satisfactory tensile strength and compression set resistance.

The monomer of component (d) used in the present invention is the mechanical properties of the resulting acrylic elastomer,
It is optionally used to improve oil resistance, cold resistance and the like. Specifically, there are acrylonitrile, styrene, vinyl acetate, vinylidene chloride, acrylic acid, ethyl methacrylate, butanediol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, etc. ~ 30 parts by weight.

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 -20 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, the peroxide group of the polymer is used for the crosslinking reaction, so that 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 a kneader, a Banbury mixer or an open 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 ordinary vulcanizates of acrylic rubber.

[0013]

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, and Table 1 in a separable flask equipped with a stirrer, a thermometer, and a reflux condenser. 100 parts of a mixture of each monomer having the composition described in 1 above 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.

[0014]

[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 vulcanizate were measured according to JIS K-6301, and the values are shown in Table 3.

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

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.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08F 236: 02)

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, (c) diene compound O.I. 5-10 parts by weight and
(D) A method for producing an acrylic elastomer, which comprises copolymerizing 0 to 30 parts by weight of at least one other monomer copolymerizable with the components (a), (b) and (c). 2. The above (b) is The acrylic elastomer according to claim 1, which is represented by the formula: wherein R represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aralkyl group, or an allyloxycarbonyl group.