JPS60186509A - Acrylic rubber composition for sealing material - Google Patents

Abstract

PURPOSE:The titled composition consisting of an acrylic acid ester and an acrylic elastomer containing a crosslinking site component in a specific proportion, capable of easily increasing the hardness and adjusting the vulcanization rate and omitting the postvulcanization, and useful for gaskets, etc. CONSTITUTION:An acrylic rubber composition obtained from (A) an acrylic acid ester momomer, e.g. ethyl acrylate, and (B) an acrylic estomer containing 15- 50wt%, preferably 25-40wt%, based on the component (A), crosslinking site component. The component (B) is obtained from for example an epoxy group- containing monomer, e.g. glycidyl methacrylate, and a halogen-containing monomer, e.g. 2-chloroethyl vinyl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an acrylic rubber composition for sealing materials that can easily increase the hardness, easily adjust the vulcanization rate, and omit post-vulcanization. Regarding.

Conventionally, acrylic rubber has excellent heat resistance, oil resistance, weather resistance, ozone resistance, etc., and is used in various sealing materials (gaskets, packings, O-rings, bearing seals, oil seals, etc.), bosses, and sealing materials. It is widely used in sudo.

However, for example, conventional sealing materials molded from acrylic rubber, such as miniature bearings, have low hardness and therefore require the insertion of a core metal due to strength issues. In order to solve this problem, methods such as increasing the amount of filler, adding phenolic resin, and increasing the crosslinking density by increasing the amount of vulcanizing agent have been implemented, but these methods The present invention eliminates these drawbacks and provides an ideal sealing acrylic rubber. The crosslinking site component is 15 to 50
This is an acrylic rubber composition for a sealing material, which is an acrylic elastomer and is characterized by containing t% by weight, preferably 25 to 40% by weight.

The hardness of the acrylic rubber composition for sealing materials can be easily increased without deteriorating various physical properties, so it is possible to mold seals that do not require a core metal. In addition, since there are many crosslinking site components, it is easy to adjust the vulcanization and speed, and it is possible to mold in a short time, and it is possible to omit post-vulcanization, which has often been a problem in the past. It is an acrylic rubber composition.

As the epoxy group-containing monomer that is the crosslinking site component in the acrylic rubber composition of the present invention, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc. are used. Ethyl vinyl ether, vinyl chloroacetate, vinyl benzyl chloride, etc. are included. In addition, acrylic acid esters that are the main components of acrylic elastomers include lower alkyl acrylates such as methyl acrylate, ethyl acrylate, and n-butyl acrylate, methoxyethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, and 2-ethoxyethyl acrylate. Alkoxyalkyl acrylates such as are used.

The present invention will be explained in detail with reference to the following examples.

Note that all parts are parts by weight.

Examples The following monomer mixtures A to 0 were copolymerized to synthesize acrylic elastomers ANC (0 is a comparative example).

<Table 1> The copolymerization reaction was performed as follows. First, 100 parts of the monomer mixture, 200 parts of water, 0.8 parts of sodium lauryl sulfonate as an emulsifier, and 2 parts of polyoxyethylene lauryl ether were charged into a reaction vessel, and the mixture was replaced with nitrogen while maintaining the liquid temperature at 50°C. Do this. Next, when 0.2 parts of ammonium persulfate and 0.2 parts of hydrogen sulfite are added, the temperature begins to rise, but this temperature is kept at 60°C.
The mixture was stirred for 1.5 hours while maintaining the temperature at C. to complete the polymerization reaction. The obtained copolymer latex was heated at about 80°C for 15 minutes.
% saline solution, the coagulated product was washed with water, and then dried to obtain an acrylic elastomer. The polymerization rate was 98% or more.

<Table 2> (1) Pz: Ohmukai Shinko Kagaku Kogyo, zinc dimethyldithiocarbamate (2) Nonsal 5x-1: manufactured by Nippon Oil & Fats Co., Ltd., potash soap (3) Nonsal 5N-i: manufactured by Nippon Oil & Fats Co., Ltd. Each of the obtained acrylic elastomers for soda soap was kneaded with an 8-inch roll according to the formulation shown in Table 2, and the corresponding formulations 11 and 11 were obtained from acrylic elastomers A, B, and C (N is a comparative example). The vulcanization temperature, vulcanization time, and physical property values of each vulcanizate are shown in Table 6.

<Table 6> In addition, when the vulcanization states of the acrylic rubber of the present invention and the conventional acrylic rubber are plotted as a graph, the results are as shown in the drawing. As can be seen from the drawing, in compound A, the torque value reaches the maximum in a short period of time, and thereafter exhibits flat vulcanization, and the torque value at a constant vulcanization time is significantly greater than that of compound B. It is clear that it is superior.

From the above results, it is possible to easily increase the hardness (JA, 9Q degrees or more, J0.7Q degrees or more) by using an acrylic elastomer with a crosslinking site component content of 15 to 50% by weight, and compared to conventional acrylic elastomers. The tensile strength, which is a drawback of rubber, can be significantly improved. In addition, conventional acrylic rubber required long post-vulcanization to satisfy various physical properties such as normal physical properties, heat aging resistance, oil resistance, etc., but the acrylic elastomer of the present invention can be cured in a short time. It can be seen that even press vulcanization alone shows good physical property values.

As described above, according to the acrylic rubber composition for sealing materials of the present invention, the hardness can be easily increased, the vulcanization rate can be adjusted and the vulcanization rate can be improved, post-vulcanization can be omitted, and various physical properties can be improved. It has excellent features such as showing excellent numerical values.

[Brief explanation of drawings]

The drawing is a graph showing the vulcanization states of the acrylic rubber of the present invention and conventional acrylic rubber. A...Blend B...Blend] Patent applicant Uchiyama Kogyo Co., Ltd.

Claims (1)

[Claims] An acrylic rubber composition for a sealing material, which is an acrylic elastomer containing 15 to 50% by weight of a crosslinking site component, which is applied to a single acrylic acid ester body.