JPS6129618B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber composition for vulcanization that has excellent resistance to rancidity and gasoline. Epichlorohydrin rubber, epichlorohydrin-ethylene oxide copolymer rubber, has been used as an automobile rubber material with an excellent balance of gasoline resistance, aging resistance, and cold resistance, but in recent years, it has become oxidized by air. Resistance to so-called rancid gasoline, which has come to contain peroxides, has become a problem. That is, when the rubber is brought into contact with or immersed in rancid gasoline, it softens in a relatively short period of time and eventually dissolves. One way to improve this drawback is to use epichlorohydrin-ethylene oxide-unsaturated epoxide terpolymer rubber having a specific molar ratio.
Alternatively, a mixture of epichlorohydrin-ethylene oxide copolymer rubber and epichlorohydrin-unsaturated epoxide copolymer rubber is added to a non-sulfur-based vulcanizing agent, specifically 2-mercaptoimidazoline,
2.4.6 - A technique has been proposed in which vulcanization is performed using a common vulcanizing agent for saturated epichlorohydrin rubber such as trimercaptotriazine. (Unexamined Japanese Patent Publication 1973-
No. 25958, Japanese Unexamined Patent Publication No. 54-25957). The advantage of using copolymer or blended rubbers of such unsaturated epoxides, such as allyl glycidyl ether, is that they can prevent softening or dissolution of rancid gasoline; however, when using the above-mentioned vulcanizing agents, harsh conditions On the other hand, when immersed in rancid gasoline at a high concentration or for a long time, it becomes brittle. The object of the present invention is to provide an epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary rubber, or epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary rubber, which eliminates the above-mentioned drawbacks by using a new vulcanizing agent and, in particular, a calcium compound as an acid acceptor. An object of the present invention is to provide an allyl glycidyl ether two-component rubber. The present invention is based on 100 parts by weight of a binary or ternary copolymer rubber or rubber mixture consisting of 55 to 98.5 mol% of epichlorohydrin, 0 to 43.5 mol% of ethylene oxide, and 1.5 to 10 mol% of allyl glycidyl ether, b 2.3-dimercaptopyrazine, or 2.3-
A vulcanizing product with excellent rancidity gasoline resistance characterized by containing 0.1 to 10 parts by weight of a vulcanizing agent made of dimercaptoquinoxaline or a derivative thereof, and 0.5 to 20 parts by weight of a calcium compound serving as an acid acceptor. It is a rubber composition. When the above a is composed of a rubber mixture, the rubber constituting this may be epichlorohydrin alone, a polymer rubber, a binary copolymer rubber with a molar ratio of epichlorohydrin and ethylene oxide of 30 to 70:70 to 30, and epichlorohydrin and allyl. Either adjust the molar ratio of the three components by mixing a binary copolymer rubber with a molar ratio of 85 to 99:15 to glycidyl ether, or adjust the molar ratio of these and epichlorohydrin-ethylene oxide-allyl glycidyl ether. 30
The molar ratio may be adjusted by mixing with a terpolymer rubber of 75:69 to 15:1 to 15. Regardless of whether it is a binary copolymer rubber, a terpolymer rubber, or a rubber mixture, if the allyl glycidyl ether component is less than 1.5 mol%, the vulcanizate tends to soften or dissolve when immersed in rancid gasoline. If it exceeds this value, it becomes brittle and is not practical. Furthermore, in the case of a three-component rubber, if the ethylene oxide content exceeds 43.5 mol%, the gasoline resistance decreases and a softening phenomenon occurs. The vulcanizing agent b is a compound represented by the following general formula (A). However, in general formula (A), R ₁ and R ₂ may be the same or different, and are hydrogen atoms or C ₁ to
A benzene ring that represents a C ₈ alkyl group, or has at least one substituent selected from halogen, nitro group, carboxyl group, lower alkyl group, and lower alkoxy group to which R ₁ and R ₂ are bonded. may be formed. R ₃ and R ₄ may be the same or different and are hydrogen atoms, alkali metals,

【formula】

[Formula] or R ₃ and R ₄ may be bonded to each other to form a >C=0 group. In this case, R ₅ and R ₆ may be the same or different and are hydrogen atoms, C ₁ to C ₁₂
alkyl group, cycloalkyl group, aryl group,
It may represent an aralkyl group, or R ₅ and R ₆ may be bonded to each other to form a 6-membered heterocyclic ring. or R ₇ represents a C ₁ to C ₁₈ group selected from an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an aralkyl group, or

[Formula] or

[Formula] represents n = 0 or n = 1, and in the case of n = 1, R ₈ is a C ₁ to C ₈ group selected from an alkylene group, an alkenylene group, or a C selected from a cycloalkylene group and an arylene group. Represents a group of ₆ to _C12 . Also above

[Formula] may form an ester bond within the same molecule or with a mercapto group of another 2.3-dimercaptopyrazine, 2.3-dimercaptoquinoxaline or a derivative thereof. Specific examples of the compound represented by general formula (A) include 2.3-dimercaptodine, pyrazine-2.3-dithiocarbonate, 5-methyl-2.3-dimercaptopyrazine, 5-ethylpyrazine-2.3-dithiocarbonate, 5.6- Dimethyl-2,3-dimercaptopyrazine, 5,6-dimethylpyrazine-2,3-dithiocarbonate, N-methyl-3(2-mercaptopyrazyl)sulfenamide, NN-dicyclohexyl-3(5-ethyl-2-mercaptopyrazyl)sulfenamide, 5-isopropyl-2-
Mercaptopyrazyl-3-thiol benzoate, 5,6-dimethyl-2-mercaptopyrazyl-
3-thiol sebacate, 2.3-dimercaptoquinoxaline, quinoxaline-2.3-dithiocarbonate, 6-ethyl-2.3-dimercaptoquinoxaline, 6-methylquinoxaline-2.3-dithiocarbonate, 6.7-di(n-butyl)-2.3- Dimercaptoquinoxaline, NN-dicyclohexyl-3(2-mercaptoquinoxalyl)sulfenamide, N-(n-butyl)-3-(6-methyl-2-mercaptoquinoxalyl)sulfenamide, 6-isopropyl-2-mercapto Quinoxalyl-3-thiol acetate, 5.8-dimethyl-2-mercaptoquinoxalyl-3-thiol benzoate, 6-isobutyl-2-mercaptoquinoxalyl-3-thiol sepacate, 6-bromo 2.3-dimercaptoquinoxaline , 6-methoxyquinoxaline-2.3-dithiocarbonate, 6-nitro-2.3-dimercaptoquinoxaline, 6-carboxyquinoxaline-2.3-dithiocarbonate, and the like. The amount of b added as a vulcanizing agent is 0.1 to 10 parts by weight per 100 parts by weight of a), preferably
It is about 0.3 to 5 parts by weight. Examples of the compound serving as an acid acceptor (c) include calcium hydroxide, conjugated calcium, calcium silicate, and calcium stearate. When these calcium-based acid acceptors are used in combination with the vulcanizing agent (b), they significantly enhance the rancid gasoline resistance of the rubber composition of the present invention, and other known acid acceptors such as magnesium compounds and lead Even if a compound or the like is substituted, the desired effect will not be achieved. The amount added is a
0.5 to 20 parts by weight per 100 parts by weight, preferably 1
~15 parts by weight. If necessary, other compounding agents commonly used in the technical field, such as acid acceptors, stabilizers, reinforcing agents, fillers, plasticizers, and anti-aging agents, can be added to the composition of the present invention. As a method for mixing the composition of the present invention, conventional means such as an open roll, a pressure kneader, and a Banbury mixer can be employed. Vulcanization temperature is usually
The temperature is 100 to 200°C, and the vulcanization time varies depending on the temperature, but it is usually carried out for 0.5 to 300 minutes. Vulcanization molding methods include pressure molding using a mold, injection molding, steam can, air bath or infrared rays,
Any method such as heating using microwaves or the like can be used. Next, the effects of the present invention will be explained using Examples and Comparative Examples. Examples 1 to 5, Comparative Examples 1 to 9 The formulations shown in Table 1 were kneaded with an open roll at 60 to 70°C, and the sheet was put into a mold.
Pressure molded at 160℃ and 80Kg/cm ² for 30 minutes to a thickness of approx.
A vulcanizate sheet of mm was obtained. Table 2 shows the rancid gasoline resistance of this vulcanizate. It is said that it is difficult to obtain rancid gasoline itself with good reproducibility.
In Table 2, lauroyl peroxide is added to fuel oil C (toluene, isooctane 1:1 volume ratio).
The vulcanizate sheet was immersed in test oil containing 2.0% by weight at 40°C or 60°C to evaluate rancidity gasoline resistance. This test method is said to be able to obtain gasoline with relatively high peroxide values with good reproducibility and to provide rubber deterioration behavior that is approximately the same as that obtained with actual rancid gasoline. Evaluation of surface adhesion, dissolution and
The brittleness was determined by a 180° bending test. The evaluation results in Table 2 show that the composition of the present invention is resistant to softening,
This shows that it is superior to the conventional technology in terms of both solubility and embrittlement resistance.

【table】

【table】

【table】

Claims (1)

[Scope of Claims] 1 a Binary or ternary copolymer rubber or rubber mixture consisting of 55 to 98.5 mol% epichlorohydrin, 0 to 43.5% ethylene oxide, and 1.5 to 10 mol% allyl glycidyl ether b 2,3- Vulcanizing agent c consisting of dimercaptopyrazine or 2,3-dimercaptoquinoxaline or a derivative thereof Calcium compound serving as an acid acceptor Based on the above a) 100 parts by weight, b) 0.1 to 10 parts by weight and c) 0.5 A rubber composition for vulcanization having excellent resistance to rancid gasoline, characterized in that it contains up to 20 parts by weight. 2. The vulcanizable rubber composition according to claim 1, wherein the calcium compound is a compound selected from calcium hydroxide, calcium oxide, calcium silicate, and calcium stearate.