JPH0481610B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a sulfur-vulcanizable acrylic copolymer rubber using a conjugated diene monomer and an epoxy group-containing unsaturated monomer. (Prior art and problems to be solved) Acrylic rubber is an elastic material whose main component is acrylic ester, and is generally known as a rubber with excellent heat resistance, oil resistance, ozone resistance, etc.
Since the main chain of the rubber molecule does not have a double bond, it is generally well known to copolymerize monomers with active groups that serve as crosslinking points. Examples of simple components that serve as crosslinking points include halogen monomers such as 2-chloroethyl vinyl ether, vinyl chloroacetate, allyl chloroacetate, vinylbenzyl chloride, 5-chloroacetoxymethyl-2-norbornene, and allyl glycidyl ether. , glycidyl acrylate,
Epoxy monomers such as glycidyl methacrylate have been commonly used. Acrylic rubber containing such monomer components cannot be vulcanized with ordinary sulfur or sulfur-containing organic compound-vulcanization accelerator systems, and amines, ammonium salts, metal soaps-sulfur, etc. are used as crosslinking agents. Although commonly used, they have the disadvantage of slow vulcanization rates and the need for long heat treatments to obtain optimal vulcanization properties. Furthermore, the use of amines and ammonium salts has the disadvantage that they generate odor during vulcanization and that the final product cannot be used for medical, food, or other purposes due to hygiene reasons. Furthermore, acrylic rubber that uses a halogen monomer as a crosslinking monomer has problems in that it corrodes the mold during vulcanization and corrodes the metal that comes into contact with the product. In order to improve these drawbacks, crosslinking monomers such as dicyclopentadiene, methylcyclopentadiene, ethylidene norbornene, vinylidene norbornene, butadiene, isoprene, piperylene, acryl acrylate, 2-butenyl acrylate, triallylisocyanurate, etc. Sulfur-curable acrylic rubber as a body component is already known, but
The vulcanization rate is not sufficient, and the vulcanization properties, heat resistance, compression set resistance, etc. are not fully satisfactory for practical purposes. (Means for Solving the Problems) As a result of various studies to improve the above drawbacks, the present inventors copolymerized a diene monomer and an epoxy group-containing unsaturated monomer as a crosslinking monomer. It was discovered that by doing so, an acrylic copolymer rubber that is sulfur-curable and has well-balanced practical properties can be obtained, and based on this knowledge, the present invention was completed. Therefore, the purpose of the present invention is to reduce the vulcanization rate, which is a disadvantage of conventional acrylic rubber, to the same level as diene rubber, without impairing the heat resistance, oil resistance, and ozone resistance, which are the characteristics of conventional acrylic rubber. An object of the present invention is to provide an improved method for producing acrylic copolymer rubber. The object of the present invention is to (1) 40 to 99.4% by weight of at least one acrylic ester selected from alkyl acrylates and alkoxyalkyl acrylates, (2) diene monomers (conjugated carbon atoms that can be copolymerized in one molecule). (excluding monomers containing one or more double bonds and one or more non-conjugated carbon double bonds) 0.5 to 20% by weight,
(3) 0.1 to 10% by weight of epoxy group-containing unsaturated monomer,
(4) A method for producing an acrylic copolymer rubber, comprising radical copolymerization with 0 to 30% by weight of at least one monomer selected from monovinyl and monovinylidene unsaturated monomers other than those mentioned above. This can be achieved by using Examples of the alkyl acrylate as component (1) used in the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, and octyl acrylate. Preferably it is an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, more preferably 2 to 4 carbon atoms. In addition, as alkoxyalkyl acrylate, methoxymethyl acrylate,
Preferred examples include those having an alkoxy group having 1 to 4 carbon atoms, such as methoxyethyl acrylate, ethoxyethyl acrylate, and butoxyethyl acrylate. The amount of these acrylic esters used is 40 to 99.4% by weight, preferably 60 to 98% by weight, based on the total monomers used (the same applies hereinafter). In addition, when using alkyl acrylate and alkoxyalkyl acrylate to satisfy the balance of oil resistance and cold resistance, alkoxyalkyl acrylate is
Preferably, it is used in combination with alkyl acrylate in a proportion by weight. The component (2) diene monomer used in the present invention includes butadiene, methylbutadiene, isobrene, piperylene, bentadiene, ethylidenenorbornene, vinylnorbornene, and the like. In the present invention, a monomer containing one or more each of one or more copolymerizable conjugated carbon double bonds and one or more nonconjugated carbon double bonds in one molecule is not used. Preferred are butadiene, isoprene, piperylene and the like. The amount of these diene monomers used is 0.5 to 20% by weight.
Preferably 1 to 15% by weight, more preferably 1 to 10% by weight
Weight%. If the amount is less than 0.5% by weight, the vulcanization rate of the resulting acrylic copolymer rubber becomes extremely slow. Furthermore, when the amount exceeds 20% by weight, the resulting acrylic copolymer rubber vulcanizate has a significantly increased hardness and a significant decrease in strength and elongation. Examples of component (3) epoxy group-containing unsaturated monomer used in the present invention include vinyl glycidyl ether, allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate. Preferred are allyl glycidyl ether and glycidyl methacrylate. The amount of these epoxy group-containing unsaturated monomers used is 0.1 to 10% by weight, preferably 0.5 to 5% by weight. If the amount is less than 0.1% by weight, the vulcanized physical properties of the resulting acrylic copolymer rubber will not be improved. Moreover, when the amount exceeds 10% by weight, the hardness of the vulcanizate of the acrylic copolymer rubber obtained becomes extremely high, and the strength and elongation are significantly reduced. Component (4) used in the present invention: Monovinyl and monovinylidene unsaturated monomers other than those listed above are used as necessary to improve the mechanical properties and oil resistance of the resulting acrylic copolymer rubber. For example, monovinyl compounds include monomers such as acrylonitrile, vinyl acetate, styrene, α-methylstyrene, and acrylamide, and monovinylidene monomers include methyl methacrylate, ethyl methacrylate, and methacrylonitrile. , and monomers such as vinylidene chloride. The amount used is 30% by weight or less. In the present invention, the acrylic polymer of the present invention is produced by polymerizing the monomer composite using a commonly used radical initiator in a known polymerization mode such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization. Polymerized rubber can be easily produced. The polymerization can be carried out batchwise or by adding one or more component monomers continuously or continuously during the polymerization. The polymerization temperature is in the range of -10°C to 100°C, preferably 2 to 80°C. The thus obtained acrylic copolymer rubber is kneaded and vulcanized with the addition of compounding agents such as sulfur vulcanization, reinforcing agents, fillers, plasticizers, and anti-aging agents, which are commonly used in diene rubbers, as necessary. This improves the vulcanizable properties and compression set resistance, which are the disadvantages of conventional acrylic rubber, without sacrificing the advantages of conventional acrylic rubber, such as heat resistance, oil resistance, and ozone resistance. A balanced acrylic copolymer rubber vulcanizate can be obtained. In addition, not only sulfur-cured copolymer rubber but also peroxide-vulcanized copolymer rubber can be used. The acrylic copolymer rubber vulcanizate obtained in the present invention is useful in many fields requiring heat resistance, ozone resistance, etc. Such uses include various rubber products such as gaskets, hoses, conveyor belts, packings, and oil seals. Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the Examples. Example 1 According to the polymerization recipe shown in Table 1, a polymerization reaction was carried out at 30°C using an autoclave with an internal volume of 10. After reaching 90% conversion, 0.2 parts by weight of hydroxylamine sulfate per 100 parts by weight of monomer was added to stop the reaction. After the completion of the reaction, the polymerization product was salted out, thoroughly washed with water, and then dried in a vacuum dryer to obtain the desired acrylic copolymer rubber.

[Front] Tan

[Table] The six types of acrylic copolymer rubbers obtained in this way were prepared according to the formulation below using an open roll under cooling, and then press vulcanized at 170°C for 20 minutes. Heat treatment was carried out at 150° C. for 16 hours in a gear oven. The properties of these vulcanizates were measured according to JISK-6301. The obtained physical properties are shown in Table 3. Acrylic copolymer rubber (see Table 2) 100 (parts by weight) Stearic acid 1 HAF carbon 50 Zinc white No. 1 3 Sulfur 0.3 Tetramethylthiuram disulfide
2

[Table] Example 2 According to the polymerization recipe in Table 1 of Example 1, and according to the monomer charging composition shown in Table 4, the same polymerization reaction and separation operation as in Example 1 were carried out to obtain the desired acrylic copolymerization. Got the rubber.

[Table] The 11 types of acrylic copolymer rubbers obtained in this way were prepared in an open roll under cooling according to the compounding recipe in Table 5, and then press vulcanized at 170°C for 20 minutes. Heat treatment was carried out at 150° C. for 16 hours in a gear oven. The properties of these vulcanizates were measured according to JISK-6301. The obtained physical properties are shown in Table 6.

【table】

[Table] As shown in Tables 3 and 6, the acrylic copolymer rubber obtained by the present invention has vulcanized physical properties that are sufficiently satisfactory for practical use after press vulcanization and heat treatment. On the other hand, the acrylic copolymer rubber of the present invention has improved vulcanization properties and compression set resistance when a sulfur vulcanization system is used.

Claims (1)

[Claims] 1 (1) 40 to 99.4% by weight of at least one acrylic ester selected from alkyl acrylates and alkoxyalkyl acrylates, (2) diene monomer (contains copolymerizable conjugated carbon double bonds and non-copolymerizable carbon double bonds in one molecule). (excluding monomers each containing one or more conjugated carbon double bonds) 0.5 to 20% by weight, (3) epoxy group-containing unsaturated monomers 0.1 to 10% by weight, (4) monovinyl series other than the above and Vulcanizable with a sulfur-based vulcanizing agent and an organic peroxide, characterized by radical copolymerization with 0 to 30% by weight of at least one monomer selected from monovinylidene unsaturated monomers. Method for producing acrylic copolymer rubber.