JPH0339529B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vulcanizable acrylic elastomer, and more particularly to a method for producing a vulcanizable acrylic elastomer having excellent properties such as kneading processability, scorch resistance, and storage stability. Conventionally, epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and vinyl glycidyl ether were added as crosslinking site components to acrylate copolymer elastomers (hereinafter abbreviated as acrylic elastomers) containing acrylic acid ester as the main component. It has already been carried out to copolymerize and introduce.
Although these acrylic elastomer vulcanizates have excellent properties such as heat resistance, weather resistance, and oil resistance, there are some problems in terms of vulcanization characteristics. That is, when a high vulcanization rate is obtained, the scorch property is significant and the kneading processability and storage stability are unsatisfactory. On the other hand, when the scorch property is in a satisfactory state, the vulcanization rate becomes slow, which hinders the efficiency of the vulcanization molding process. The object of the present invention is to solve the above-mentioned problems of conventional acrylic elastomers, that is, to provide an acrylic elastomer that can achieve a sufficiently high vulcanization rate and at the same time has excellent scorch resistance. As a result of various studies carried out for the purpose of the present invention, it was discovered that the present invention can be achieved by copolymerizing two types of epoxy group-containing monomers with different structures as crosslinking site components in an acrylic elastomer. That is, the aquaryl elastomer of the present invention contains about 60 to 99% by weight of at least one acrylate selected from the group consisting of alkyl acrylates and alkoxyalkyl acrylates, about 9.5 to 2% by weight of epoxy group-containing monomer A, Copolymerizing about 0.5 to 8% by weight of an epoxy group-containing monomer B having a different structure from A, and about 30 to 0% by weight of at least one other polymerizable monomer that can be copolymerized with these monomers. It is made by containing. Comonomer components forming the acrylic elastomer include, for example, alkyl acrylates such as methyl acrylate, ethyl acrylate, n- or isopropyl acrylate, n- or isobutyl acrylate, methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, -Alkoxyalkyl acrylates such as ethoxyethyl acrylate are used. Allyl glycidyl ether is used as the epoxy group-containing monomer A, and glycidyl methacrylate is used as the epoxy group-containing monomer B. In this case, in order to obtain favorable vulcanization properties, 5 to 3% by weight of allyl glycidyl ether, glycidyl methacrylate,
0.5-2.5% by weight is used. Examples of other polymerizable monomers include vinyl chloride, vinylidene chloride,
Acrylonitrile, methacrylonitrile, styrene, -methylstyrene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, methyl methacrylate, ethyl methacrylate, divinylbenzene, ethylene glycol diacrylate, acrylic methacrylate, and the like are used. These polymerizable monomers are used in an amount of about 30 to 0% by weight, preferably about 20 to 5% by weight of the total comonomers. The vulcanization operation usually involves combining the vulcanizing agent components, such as aliphatic soaps with sulfur or sulfur-donating compounds, polyamines, dithiocarbamates or ammonium organic carboxylic acids, with other ingredients, such as reinforcing agents, fillers, and as needed. The elastomer is mixed with vulcanization accelerators, anti-aging agents, stabilizers, plasticizers, lubricants, processing aids, etc., using commonly used mixing methods such as roll mixing, Banbury mixing, kneader mixing, and solution mixing. This is done by vulcanizing after The vulcanization temperature is generally approximately
Temperatures of 120°C or higher, preferably about 150°C or higher are used. Next, the present invention will be explained with reference to implementation sequences. Example Synthesis of acrylic elastomer Comonomer mixtures A to D having the monomer compositions (parts by weight) shown in Table 1 below were copolymerized to produce acrylic elastomers A to D (C and D are comparative examples), respectively. was synthesized.

[Table] The copolymerization reaction was carried out as follows. First, 100 parts of monomer mixture (weight, same below), 0.01 part of dodecyl mercaptan, 2 parts of polyoxyethylene lauryl ether, sodium lauryl sulfate.
Put 0.8 parts and 200 parts of water into a reaction container and bring the temperature of the liquid to about 50.
While maintaining the temperature at °C, the atmosphere was sufficiently replaced with nitrogen. Next, when 0.2 parts of ammonium persulfate and 0.2 parts of sodium bisulfite were added, a polymerization reaction was initiated and the temperature began to rise, but the polymerization reaction was completed by stirring for about 1 hour while maintaining this temperature at about 60°C.
The obtained copolymer latex was poured into 15% saline solution at about 80°C, the coagulated material was washed with water, and then dried to obtain an acrylic elastomer. The polymerization rate is 98 in all cases.
% or more. Each of the obtained acrylic elastomers A,
For B, C and D, acrylic elastomer
100 parts of clay, 90 parts of clay, 1 part of stearic acid, and 2 parts of zinc methyldithiocarbamate were mixed according to a recipe, and the mixture was kneaded with an 8-inch roll to prepare the corresponding products. Each formulation was press cured at a vulcanization temperature of 180°C for 8 minutes and post-vulcanized at 150°C for 15 hours. Measure the Mooney scorch (120℃, the time required for the Mooney viscosity to reach the minimum value + 5, which is a measure of processing stability and storage stability) of each compound and various physical property values of each vulcanizate. did. Table 2 shows the physical property values of each Mooney scorch compound and each vulcanizate.

[Table] Based on the above results, the results of comparing the vulcanization effects of the acrylic elastomer of the present invention and the conventional acrylic elastomer are summarized in Table 3 below.

[Table] As can be seen from Tables 2 and 3 and the drawings, when the epoxy group-containing monomer is used alone, the vulcanization rate and scorch property are not balanced. That is, when a fast vulcanization rate is obtained, the scorch property is significant, and conversely, when the scorch property is in a satisfactory state, the vulcanization rate is slow. In comparison, the acrylic elastomer of the present invention has a sufficiently high vulcanization rate and excellent scorch resistance. Therefore, it has excellent roll processability and vulcanization moldability, and can be vulcanized for a short time without impairing storage stability.

[Brief explanation of the drawing]

The drawing is a graph showing the vulcanization states of the acrylic elastomer of the present invention and a conventional acrylic elastomer. The vertical axis shows torque (Kg cm), and the horizontal axis shows vulcanization time. is the acrylic elastomer of the present invention, is
A conventional acrylic elastomer is a conventional acrylic elastomer.

Claims (1)

[Scope of Claims] 1. At least one selected from the group consisting of alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, and alkoxyalkyl acrylates in which the alkyl group and the alkylene group each have 1 to 4 carbon atoms. 1 type of acrylate 60 to 90% by weight, 2 epoxy group-containing monomer A 9.5 to 2% by weight, 3 epoxy group-containing monomer with a different structure from A.
B0.5 to 8% by weight, 4. In the epoxy group-containing monomer, A is allyl glycidyl ether and B is glycidyl methacrylate. 5. At least one monomer that can be copolymerized with these monomers.
A method for producing a vulcanizable acrylic elastomer, comprising copolymerizing 30 to 0% by weight of other polymerizable monomers and the monomers 1 to 5 above.