JPS59136303A - Production of vulcanizable acrylic rubber - Google Patents

Abstract

PURPOSE:To provide the titled rubber having excellent heat resistance, oil resistance, weather resistance, etc., by copolymerizing an acrylic acid ester monomer with a specific amount of an acetoacetic acid monomer having active methylene group, and vulcanizing the resultant copolymer with a thiuram-type vulcanizing agent. CONSTITUTION:98-90wt%, preferably 98-94wt% of an acrylic acid ester monomer is copolymerized with 2-10wt%, preferably 2-6wt% of an acetoacetic acid monomer having active methylene group (allyl acetoacetate). The obtained copolymer is vulcanized with a thiuram-type vulcanizing agent (e.g. tetramethylthiuram disulfide) to obtain the objective acrylic rubber. EFFECT:The rubber has excellent ozone resistance, flex cracking resistance, etc., is vulcanizable at low temperature, and has a high vulcanization rate and high roll processability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing heatable acrylic rubber, and more specifically, an acetoacetate monomer having an active methylene group of 2 to 10% by weight based on an acrylate monomer. It is characterized by adding polymers and polymerizing them.

Conventional acrylic rubber is stable against heat and oil resistance is also cited as one of its advantages due to the polarity of its ester structure, but it has an unsaturated group, that is, a double bond, in the rubber molecule. sulfur vulcanization was impossible.

Therefore, in conventional acrylic rubber, halogen-based vulcanizing agents such as 2-chloroethyl vinyl ether and vinyl chloroacetate, or allyl glycidyl ether, which react with vulcanizing agents such as fatty acid soap and amines such as ethyltetramine and tetraethylpentamine, have been used. Acrylic rubber was obtained by copolymerizing an appropriate amount of an epoxy crosslinking monomer such as glycidyl acrylate or glycidyl methacrylate with an acrylic ester, and vulcanization was performed.

However, such a vulcanization system has the disadvantage that it is unstable against moisture and causes the dough of the kneaded rubber to burn.

In addition, the conventional acrylic rubbers mentioned above have poor cold resistance and processability, and those that use liquid polyamines in the vulcanization system have problems such as roll tackiness, storage stability, corrosivity, and amine odor. Toxicity was considered a defect.

In view of the above-mentioned defects of acrylic rubber, the present invention was developed as a result of intensive research into a method for producing vulcanized acrylic rubber that eliminates these defects.

That is, in the present invention, acrylic rubber can be obtained by adding an acetic acid monomer having an active methylene group to an acrylic acid ester monomer, which is a raw material for acrylic rubber, and polymerizing it. We succeeded in crosslinking rubber using a vulcanizing agent of this type.

The acetoacetic acid monomer having an active methylene group used in the present invention includes esters of ketene dimer and unsaturated alcohol, such as allyl acetoacetate and methallyl acetoacetate.

An example of a method for manufacturing these acetoacetic acid monomers is to add 0.4 parts by weight of sodium acetate as a catalyst to 62 parts by weight of allyl alcohol and heat at 110 to 115°C while refluxing.
The reaction is carried out by adding 96 parts by weight of ketene dimer in portions using a separating funnel over a period of about 2 hours, and after the reaction is completed, the product is distilled under reduced pressure.

In the present invention, the ratio of acetoacetic acid monomer to acrylic ester monomer is 2 to 10% by weight, preferably 2 to 6% by weight.

If this amount is less than 2% by weight, there will be no effect of introducing acetoacetate groups, and if it is more than 10% by weight, the vulcanization time will be faster, the curing force will increase, or the hardness will increase, resulting in elongation. This is undesirable because it reduces flexibility and flexibility.

In the present invention, tetramethylthiuram disulfide or tetraethylthiuram disulfide is most suitable as the vulcanizing agent used to vulcanize the copolymer obtained by emulsion polymerization of an acrylic acid ester monomer and a monomer having an acetoacetate group. In addition, tetramethylthiuram monosulfide or thiazole is used as a promoter.

The acrylic rubber of the present invention thus obtained has remarkable vulcanization speed and flatness compared to conventional acrylic rubber. It is clear from the curve.

In addition, the acrylic rubber of the present invention not only maintains the properties of other acrylic rubbers such as heat resistance, oil resistance, weather resistance, ozone resistance, and flex crack resistance, but also has the following properties: It has excellent advantages not found in other acrylic rubbers, such as: (1) rapid vulcanization; and (2) good roll processability.

The acrylic rubber of the present invention is used for molding seals, gaskets, O-rings, hoses, rolls, and the like.

Next, Examples will be shown to further specifically explain the present invention. Note that this example does not limit the present invention in any way.

All parts are by weight.

Example 1 The following monomer composition (parts by weight) Monomer mixture A-B/C-D
were copolymerized to form acrylic elastomers A and B-
CD was synthesized.

Table 1 The copolymerization reaction was carried out as follows.

First, 100 parts of a monomer mixture, 200 parts of water, and sodium lauryl sulfonate (Kaoh emal 1
0, manufactured by Kao Soap Co., Ltd.) and 2 parts of polyoxyethylene lauryl ether (Kaoh Emulgen 120 manufactured by Kao Soap Co., Ltd.) were charged into a reaction vessel, and the mixture was sufficiently purged with nitrogen while maintaining the liquid temperature at about 50°C.

Next, when 0.2 parts of ammonium persulfate and 0.2 parts of sodium hydrogen sulfite are added, the polymerization reaction starts and the temperature begins to rise, but the polymerization reaction is continued by stirring for about 1 hour while maintaining this temperature at about 60°C. The copolymer latex thus obtained was poured into 10% saline solution at about 60° C., and the coagulated product was washed with water and dried to obtain an acrylic elastomer. The polymerization rate was 98% or more in all cases.

Each of the obtained elastomers was kneaded using an 8-inch roll according to a formulation consisting of 100 parts of acrylic elastomer, 1 part of stearic acid, 90 parts of clay, 2 parts of tetramethylthiuram disulfide, and 2 parts of dibenzothiazyl disulfide. A,
B, C1 and D respectively corresponding formulations 1,1.
Ill, and ■ were prepared.

Each formulation was press cured at a vulcanization temperature of 150°C for 4 minutes and then post-vulcanized at 150°C for 3 hours. Next, various physical property values of each vulcanizate were measured, and the values are shown in Table 21, Table 3, Table 4, and Table 5.

From the above results, conventionally it was necessary to press vulcanize at 180°C for 8 minutes and then post-vulcanize at 180°C for 4 hours or more, but by copolymerizing the monomer having an acetoacetate group according to the present invention. Acrylic elastomers show good physical properties despite vulcanization at low temperatures and short times. I understand that.

[Brief explanation of the drawing]

The drawing is a graph showing the vulcanization state of the acrylic rubber of the present invention and the conventional acrylic rubber at 150°C. A... Conventional acrylic rubber B... Patent applicant for the acrylic rubber of the present invention Uchiyama Kogyo Co., Ltd. Vulcanization time (minutes) Procedural amendment (method) 1. Indication of the case Patent application No. 10911 of 1988 2
, Title of the invention Method for producing vulcanizable acrylic rubber 6
Relationship with the case of the person making the amendment Patent applicant Address: 65B-4 Enami, Okayama City, Date of amendment order: Amendment based on the notice of reasons for refusal dated April 26, 1981. 5. Target of amendment 1 Table 11t+6 of the specification, Contents of amendment 'Table If1 of page 6.8.9 of the specification
1. The copolymerization reaction was carried out as follows. First, 100 parts of a monomer mixture, 200 parts of water, and sodium lauryl sulfonate (Kaoh emal 1
0.0, manufactured by Kao Soap Co., Ltd.) and 2 parts of polyoxyethylene lauryl ether (Kaoh Emulgen 120 manufactured by Kao Soap Co., Ltd.) were charged into a reaction vessel, and the mixture was sufficiently purged with nitrogen while maintaining the liquid temperature at about 50°C. Next, when 0.2 parts of ammonium persulfate and 0.2 parts of hydrogen sulfite were added, the polymerization reaction started and the temperature started to rise, but the temperature was kept at about 60°C and stirred for about 1 hour. to complete the polymerization reaction, and the obtained copolymer latex was mixed with about 60 Table 2 (Formulation I) Table 3 (Formulation I) Table 4 (Formulation 1 it) Table 5 (Formulation ■) 25-

Claims (1)

[Claims] Copolymerize by adding 2 to 10% by weight of a monomer having an acetoacetate group to 98 to 90% by weight of an acrylic acid ester monomer, and add a thiuram-based vulcanizing agent to the resulting copolymer. A method for producing vulcanized IJ-Lz rubber characterized by vulcanization.