JPH09132605A - 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 30-99.5 pts.wt. at least one acrylate selected from among alkyl acrylates with a 1-8C alkyl with 0.5-10 pts.wt. polymerizable-unsaturation-containing peroxide, 0.5-30 pts.wt. compound having a methylene or methine group having an oxygen atom in the position α and having one polymerizable unsaturation and 0-60wt.% 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.

[0003]

Since the acrylic elastomer does not have a double bond in the polymer main chain, a cross-linking site-donating monomer is copolymerized, and a cross-linking agent is selected according to the cross-linking site. And cross-linking. Active halogen groups, epoxy groups, vinyl groups, etc. are used as the cross-linking sites. An acrylic elastomer having an active halogen group is inferior in metal corrosion resistance and water resistance because it is a by-product produced in the vulcanization process. Acrylic elastomers having an epoxy group have a slow vulcanization rate and require secondary vulcanization for a long time in order to obtain optimum vulcanization properties. Methods of vulcanizing the acrylic elastomer copolymerized with a diene compound include sulfur vulcanization and peroxide vulcanization. In particular, peroxide vulcanization is fast, and in some cases secondary vulcanization can be omitted, and the resulting vulcanizate is satisfactory in heat resistance and compression set resistance.
However, it has a drawback that the processability of the obtained polymer is poor because side reactions specific to the diene compound such as chain transfer reaction and gelation reaction occur during the polymerization reaction.

As a result of intensive studies, the inventors of the present invention have obtained a polymerizable unsaturated group-containing peroxide and one polymerizable unsaturated group having a methylene group or a methine group having an oxygen atom at the α-position. It has been found that the acrylic elastomer obtained by copolymerizing the compound has good processability, and the vulcanized product obtained has good tensile strength, heat resistance, and compression set resistance.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
(A) 30 to 99.5 parts by weight of at least one acrylate selected from alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, and (b) 0.5 to 0.5 of a polymerizable unsaturated group-containing peroxide. 10 parts by weight, (c) 0.5 to 30 parts by weight of a compound having a methylene group or a methine group having an oxygen atom at the α-position, and having one polymerizable unsaturated group, and
(D) It is achieved by copolymerizing 0 to 60 parts by weight of at least one other monomer copolymerizable with the components (a), (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,
Examples thereof include alkyl acrylates having an alkyl group having 1 to 8 carbon atoms such as octyl acrylate and cyanoethyl acrylate. The amount of these acrylates used is 30 to 99.5 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 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 a compound having a methylene group or a methine group having an oxygen atom at the α-position and having one polymerizable unsaturated group,
Used as a crosslinking site donating monomer. Specifically, it is a compound having an alkoxyalkylene group having 1 to 8 carbon atoms, a dioxymethylene group, or a cyclic ether group, and having one polymerizable unsaturated group. For example, ethoxymethyl acrylate, methoxyethyl acrylate, 3-methoxybutyl acrylate, ethoxyethoxyethyl acrylate, 1,2- (methylenedioxy) -4-propenylbenzene, 3,4- (methylenedioxy) -styrene, tetrahydroflur Furyl acrylate, tetrahydrofurfuryl methacrylate and the like can be mentioned. The amount of these used is 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight. These monomers are
If the amount is less than 5 parts by weight, satisfactory values cannot be obtained in the physical properties of the vulcanizate obtained, especially in the mechanical properties. On the other hand, if it is 30 parts by weight or more, the heat resistance of the obtained vulcanizate decreases. Also,
Some of these monomers have not only an effect as a crosslinking site donor but also an effect of improving physical properties such as cold resistance and oil 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, and the like. Alkoxy acrylates other than) may be used. The amount of these monomers used is 0 to 60 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. Since the elastomer obtained by the polymerization does not use a diene compound as a crosslinking site monomer, the above-mentioned side reaction cannot occur during the polymerization. Therefore, there is no problem in processability such as roll processability and vulcanization moldability. 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, 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 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. Further, secondary vulcanization may be performed at the same temperature.

[0012]

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.

[0013]

[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.

[0014]

[Table 2]

[0015]

[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 acrylic elastomer of the present invention has good processability, and the vulcanized product thereof has excellent tensile strength, heat resistance, and compression set resistance.

Claims (5)

[Claims] 1. (a) 30 to 99.5 parts by weight of at least one acrylate selected from alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, (b) a polymerizable unsaturated group-containing peroxide. 0.5 to 10 parts by weight, (c) α
0.5 to 30 parts by weight of a compound having a methylene group or a methine group having an oxygen atom at the position and having one polymerizable unsaturated group, and (d) the above (a), (b), (c) A method for producing an acrylic elastomer, which comprises copolymerizing 0 to 60 parts by weight of at least one other monomer copolymerizable with a component. 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. 3. The above-mentioned (c) has an alkoxyalkylene group having 1 to 8 carbon atoms and has a polymerizable unsaturated group of 1
The acrylic elastomer according to claim 1, which has one piece. 4. The acrylic elastomer according to claim 1, wherein (c) has a dioxymethylene group and has one polymerizable unsaturated group. 5. The acrylic elastomer according to claim 1, wherein (c) has a cyclic ether group and has one polymerizable unsaturated group.