JPH0796641B2 - Rubber mixture - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition which is a mixture of an epichlorohydrin-propylene oxide copolymer rubber and a chlorinated rubber and which has comprehensively excellent physical properties. is there.

(Prior Art) Among existing oil resistant rubbers, chlorinated polyethylene rubber (hereinafter sometimes referred to as CPE) and chlorosulfonated polyethylene rubber (hereinafter sometimes referred to as CSM), which are chlorinated rubbers, have various characteristics. As a well-balanced and excellent synthetic rubber, it is widely used in automobile hose covers, dust cover boots, belts and other applications. CPE and CSM have been used because of their excellent oil resistance, heat resistance, ozone resistance, bending resistance, etc., but they are not suitable for use in cold regions due to their poor cold resistance.

On the other hand, epichlorohydrin-ethylene oxide copolymer rubber (hereinafter sometimes referred to as CHC) has excellent heat resistance, oil resistance, cold resistance, and dynamic ozone resistance, but is poor in flex resistance and requires dynamic characteristics. Is not suitable as a material.

Further, the epichlorohydrin-propylene oxide copolymer rubber is excellent in heat resistance, oil resistance, cold resistance and dynamic ozone resistance, but is still insufficient in flexibility.

(Problems to be solved by the invention) Accordingly, an object of the present invention is to provide a rubber composition which has heat resistance, oil resistance and flexibility equivalent to those of CPE and CSM and which has improved cold resistance than CPE and CSM. To provide.

(Means for Solving the Problems) The purpose of the present invention is to provide epichlorohydrin of 10 to 60 mol%, propylene oxide or propylene oxide and ethylene oxide (provided that the molar ratio of propylene oxide and ethylene oxide is 1 or more) 30 to 90 mol%. And a rubber mixture characterized in that it comprises 90 to 40% by weight of a copolymer rubber containing 0 to 15 mol% of an unsaturated epoxide and 10 to 60% by weight of a chlorinated rubber.

The copolymer rubber in the present invention is obtained by copolymerizing epichlorohydrin and propylene oxide or propylene oxide and ethylene oxide, and optionally an unsaturated epoxide.

Examples of unsaturated epoxides include allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate, and butadiene monoxide. By copolymerizing an unsaturated epoxide, thermal softening deterioration and dynamic ozone resistance are improved, but if it exceeds 15 mol%, curing type deterioration due to heat will occur and the rubber elasticity will be lost, resulting in a brittle defect. Further, the amount of propylene oxide or the total amount of propylene oxide and ethylene oxide is appropriately determined in the range of 30 to 90 mol% according to the cold resistance required for the rubber molded product, but if the amount is less than 30 mol%, the cold resistance is low. If the amount exceeds 90 mol%, the oil resistance decreases and the degree of swelling increases. A particularly preferable ratio of the copolymerization component is 15 to 55 mol% of epichlorohydrin, 35 to 85 mol% of propylene oxide or a total of propylene oxide and ethylene oxide, and 2 to 10 mol% of unsaturated epoxide. If the molar ratio of propylene oxide and ethylene oxide is less than 1, the flex resistance will be insufficient.

The chlorinated rubber in the present invention is typically a chlorinated polyethylene rubber, chlorinated polyethylene rubber,
Chlorosulfonated polyethylene rubber is preferred.

In the mixing of the copolymerized rubber and the chlorinated rubber in the present invention, the proportion of the copolymerized rubber is appropriately determined within the range of 90 to 40% by weight according to the performance required for the rubber molded product. 90% by weight
If it exceeds 40%, the bending resistance is lowered, and if it is less than 40% by weight, problems occur in cold resistance.

As the vulcanizing agent for the mixture of the copolymer rubber and the chlorinated rubber of the present invention, since each contains a chlorine atom, a polythiol-based vulcanizing agent capable of causing a vulcanization reaction via a chlorine atom, thiourea-based A vulcanizing agent can be used, and a sulfur-based vulcanizing agent can also be used in a copolymer rubber obtained by copolymerizing an unsaturated epoxide and a chlorinated rubber containing an unsaturated double bond.

The polythiol-based vulcanizing agent may be a polythiol-based vulcanizing agent commonly used in CHC, and may be a di- or trithiol-S-triazine compound (for example, described in JP-B-48-36926), 2,5-dimercapto-1. , 3,4-thiadiazole compound (for example, described in U.S. Pat. No. 4,288,576), 2,3-dimercaptopyrazine compound (for example, described in Japanese Patent Publication No. 58-14468), 2,3-dimercaptoquinoxaline compound (for example, Japanese Patent Publication No. 58-14469), 3,5-dimercapto-
Examples include 1,2,4-triazole compounds (for example, described in JP-B-57-46463).

Examples of the thiourea-based vulcanizing agent include a 2-mercaptoimidazoline (ethylenethiourea) compound and a 2-mercaptopyrimidine compound (both are described, for example, in JP-B-43-5758).

The sulfur-based vulcanizing agent may be a sulfur-based vulcanizing agent that is usually used for diene rubbers, such as sulfur and thallium compounds such as morpholine disulfide and tetramethylthiuram disulfide, and high molecular polysulfides. Examples include sulfur donors.

The amount of vulcanizing agent used is a mixture of copolymer rubber and chlorinated rubber.
Per 100 parts by weight, it is 0.1 to 5 parts by weight in the case of sulfur and 0.1 to 10 parts by weight in the case of vulcanizing agents other than sulfur. It is of course possible to use a vulcanizing agent together.

The rubber composition of the present invention comprises a mixture of epichlorohydrin and propylene oxide or propylene oxide and ethylene oxide, and optionally an unsaturated epoxide copolymerized rubber and a chlorinated rubber, and a vulcanizing agent and, if necessary, vulcanization acceleration. It is prepared by mixing conventional rubber compounding agents such as agents, reinforcing agents, fillers, plasticizers and antioxidants in a conventional mixer such as a roll or Banbury mixer.

A rubber vulcanizate is obtained by heating this rubber composition in a desired mold usually at 100 to 250 ° C.

(Effect of the invention) This vulcanizate is comprehensively excellent in oil resistance, flex resistance, heat resistance, cold resistance and dynamic ozone resistance, so that it can be used especially for hose covers of automobiles, especially dust cover boots and It is useful for parts that require dynamic characteristics such as belts.

(Example) Next, an Example demonstrates this invention concretely. The numerical values in the compounding recipe and the rubber mixture mean parts by weight.

Example 1 An epichlorohydrin-propylene oxide-allyl glycidyl ether-based copolymer rubber prepared by a known solution polymerization method using an organoaluminum compound-based polymerization catalyst and a chlorinated polyethylene rubber were cooled together with other compounding agents according to the following formulation. A roll was mixed and heated at 170 ° C for 15 minutes to prepare a vulcanized product.

Compounding formula Epichlorohydrin-propylene oxide-allyl glycidyl ether copolymer rubber 70 Chlorinated polyethylene ^{* 1} 30 Stearic acid 3 HAF carbon 32 SRF carbon 15 Magnesium oxide 5 2,4,6-Trimercapto-s-triazine 1 1,3-diph Enylguanidine 0.2 Nickel dibutyldithiocarbamate 1.5 * 1 Eraslen 401A, a product of Showa Denko KK Then, the properties of the vulcanizates were measured according to JIS K-6301.

The results are shown in Table 1. From the table, it can be seen that the vulcanizate of Comparative Example 5 has poor cold resistance and flex resistance.

Example 2 Epichlorohydrin (30 mol%)-Propylene oxide (67 mol%)-Allyl glycidyl ether (3 mol%)
The copolymer rubber and the chlorosulfonated polyethylene rubber of Example 1 were mixed with other compounding agents on a cooling roll in accordance with the compounding recipe of Table 2, and the obtained compound was mixed with a compounding ratio shown in Table 3 on a cooling roll. Prepared.

Then, in the same manner as in Example 1, the vulcanizate was prepared and the properties were measured. Note that the dynamic ozone deterioration test was conducted in a 40 ° C atmosphere,
The ozone concentration was 50 pphm and the test piece was evaluated under a dynamic condition that gave 0 to 30% elongation to determine the crack state.

The results are shown in Table 3.

Example 3 Epichlorohydrin (30 mol%)-Propylene oxide (67 mol%)-Allyl glycidyl ether (3 mol%)
Each of the copolymer rubber and the chlorinated polyethylene rubber of Example 1 was cooled on a cooling roll together with other compounding agents according to the compounding recipe of Table 4 to prepare a mixture at a compounding ratio shown in Table 5 on a cooling roll. . Table 5 shows the results of tests performed thereafter in the same manner as in Example 1.

Claims (1)

[Claims] 1. A copolymer comprising 10 to 60 mol% of epichlorohydrin, 30 to 90 mol% of propylene oxide or propylene oxide and ethylene oxide (where the molar ratio of propylene oxide and ethylene oxide is 1 or more), and 0 to 15 mol% of unsaturated epoxide. Polythiol-based vulcanizing agent, thiourea-based vulcanizing agent or sulfur-based vulcanizing agent to 100 parts by weight of a mixture of polymerized rubber 90 to 40% by weight and chlorinated polyethylene rubber or chlorosulfonated polyethylene rubber 10 to 60% by weight. A rubber mixture comprising 0.1 to 10 parts by weight.