JPS6333789B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel oil-resistant rubber composition. Acrylic nitrile is a typical oil-resistant rubber.
There are butadiene copolymer rubbers, epichlorohydrin rubbers, acrylic rubbers, etc., and they are used depending on the usage environment. However, in recent years, various problems have arisen as the components of fuel oil and lubricating oil have changed. For example, the aromatic hydrocarbon content of fuel oil is increasing, and the types and amounts of various additives are increasing in lubricating oil.
It has become necessary to improve the resistance of rubbers that come into contact with or be immersed in these materials as much as possible so as not to cause deterioration in physical properties or deterioration due to the effects of additives. On the other hand, deterioration caused by oil degraded by oxidation in the air, so-called rancid oil, is also a major problem for oil-resistant rubber products. As a countermeasure for this type of problem, fluororubber is often used as a substitute due to its excellent performance, but this rubber has the drawbacks of being very expensive and having significantly poor cold resistance. Generally speaking, as oil resistance improves, cold resistance of rubber decreases, and epichlorohydrin-ethylene oxide copolymer rubbers are known as rubbers that have both high oil resistance and cold resistance. Rubber is susceptible to deterioration due to various additives in the oil or rancid oil. As described above, due to its molecular structure, epichlorohydrin rubber is susceptible to the effects of lubricating oil additives due to oxidative decomposition (oxidative deterioration) of the polyether main chain and the presence of chlorine, and the possibility of corrosion to metals poses a problem. In addition, nitrile rubber has poor ozone resistance due to the presence of unsaturated bonds and is susceptible to embrittlement during aging. Furthermore, the balance between oil resistance and cold resistance is poor. Furthermore, although acrylic rubber has excellent lubricating oil resistance, it has extremely poor resistance to fuel oil and very poor cold resistance. Under these circumstances, there is a desire for an inexpensive rubber that has both high oil resistance and cold resistance, and has improved resistance to the above-mentioned additives, rancid oil, and the like. The present inventors have arrived at the present invention as a result of intensive research to satisfy these conditions, that is, the main chain structure of the present invention is composed of 10 mol% or more of structural units represented by the following formula () and the formula (). A copolymer consisting of 1 mol% or more of the structural unit represented by and/or the structural unit represented by the formula () and having a reduced viscosity of 0.8 or more when measured in a 0.1% monochlorobenzene solution at 80°C, and An oil-resistant rubber composition characterized by containing a vulcanizing agent for a copolymer. (However, in the formula (), R represents a saturated alkyl group having 1 to 4 carbon atoms). (However, in the formula (), Y represents an allyloxy group, an acryloxy group, a methacryloxy group, or a sorboxy group). (However, in the formula (), X represents a chlorine atom, a bromine atom, or a chloroacetoxy group). In the copolymer of the present invention, the monomer forming the structural unit represented by the above formula () has the following general formula: (However, R represents a saturated alkyl group having 1 to 4 carbon atoms.) It is a glycidyl ester of a saturated aliphatic carboxylic acid represented by One species or two or more species are particularly preferred, and glycidyl acetate and glycidyl propionate are particularly preferred. In the copolymer of the present invention, the monomer forming the structural unit represented by the above formula () has the following general formula: (However, Y represents an allyloxy group, an acryloxy group, a methacryloxy group, or a sorboxy group.) It is an ethylenically unsaturated group-containing epoxide represented by: Selected from glycidyl sorbate. In the copolymer of the present invention, the monomer forming the structural unit represented by the above formula () has the following general formula: (However, X represents a chlorine atom, a bromine atom, or a chloroacetoxy group.) It is a halogen-containing epoxide represented by the following formula, and is specifically selected from epichlorohydrin, epibromohydrin, and glycidyl monochloroacetate. Specific examples of various copolymers used in the present invention are as follows. Glycidyl acetate-allyl glycidyl ether copolymer Glycidyl propionate-allyl glycidyl ether copolymer Glycidyl butyrate-allyl glycidyl ether copolymer Glycidyl acetate-glycidyl acrylate copolymer Glycidyl acetate-glycidyl methacrylate copolymer Glycidyl acetate -Glycidyl monochlorate copolymer Glycidyl acetate-epihalohydrin copolymer Glycidyl propionate-epihalohydrin copolymer Glycidyl butyrate-epihalohydrin copolymer Glycidyl acetate-epihalohydrin-allyl glycidyl ether copolymer Glycidyl acetate-epihalohydrin-glycidyl acrylate Copolymer Glycidyl acetate-epihalohydrin-glycidyl methacrylate copolymer Glycidyl acetate-epihalohydrin-glycidyl sorbate copolymer Glycidyl acetate-glycidyl propionate-allyl glycidyl ether copolymer Glycidyl acetate-glycidyl propionate-glycidyl acrylate Copolymer Glycidyl acetate-glycidyl propionate-glycidyl methacrylate copolymer Glycidyl acetate-glycidyl propionate-glycidyl sorbate copolymer Glycidyl acetate-glycidyl propionate-glycidyl monochlorate copolymer Glycidyl acetate-glycidyl methacrylate copolymer Pionate-epihalohydrin copolymer (in the above epihalohydrin represents epichlorohydrin and/or epibromohydrin). These copolymers contain at least 10 mol% or more of carboxylic acid glycidyl ester as a comonomer component. If the content of the above components is less than 10 mol%, the oil resistance of the vulcanized rubber decreases, which is not preferable. Further, it is necessary that at least 1 mol % or more of an epoxide having an ethylenically unsaturated group or a halogen-containing epoxide serving as a vulcanizing functional group is contained. For example, in carboxylic acid glycidyl ester-allyl glycidyl ether copolymer, the former is
The latter is preferably in the range of 80 to 99 mol%, and the latter in the range of 20 to 1 mol%. In the carboxylic acid glycidyl ester-epihalohydrin copolymer, the former is preferably in the range of 20 to 95 mol%, and the latter is in the range of 5 to 80 mol%. These copolymers are prepared using a thermal condensation product of a) an organotin compound and b) an alkyl ester of orthophosphoric acid or polyphosphoric acids as a catalyst, which is disclosed in U.S. Pat. No. 3,773,694 filed by the present applicant. It can be obtained by ring-opening copolymerization. The polymerization reaction is usually carried out at a temperature range of 10 to 80°C in the presence or absence of a solvent, the appropriate amount of catalyst is 0.01 to 1.0 g per 100 g of monomer, and the moisture in the reaction system is kept as low as possible. It is desirable to keep it low. The copolymer thus obtained is
It is a rubbery random copolymer with a reduced viscosity of 0.8 or more when measured in a 0.1% monochlorobenzene solution at 80°C. The composition of the present invention can contain polymers other than the above copolymers as polymer components. There are no particular restrictions on these polymers, but those that can be vulcanized using the same vulcanization system as the above-mentioned copolymers are preferred. For example, preferred polymers for copolymers with monomers having ethylenically unsaturated groups such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, and ethylene rubber. -propylene-
Examples include butadiene rubber, butyl rubber, halogenated butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, epichlorohydrin-allyl glycidyl ether copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, unsaturated group-containing acrylic rubber, etc. be able to. Preferred polymers for copolymers with halogen-containing monomers such as epihalohydrin and glycidyl monochloroacetate include epichlorohydrin homopolymer rubber, epichlorohydrin-
Allyl glycidyl ether copolymer rubber, epichlorohydrin-ethylene oxide copolymer rubber,
Examples include epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, chloroprene rubber, chlorine-containing acrylic rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber, fluorinated rubber, and brominated butyl rubber. As the vulcanizing agent used in the composition of the present invention having these polymer compositions, when the comonomer component of the copolymer is an ethylenically unsaturated epoxide, a known vulcanizing agent for unsaturated rubber can be used. Examples of such vulcanizing agents include organic peroxides, sulfur, sulfur donating compounds, sulfur compound accelerators, combinations of these and various accelerators, mercaptotriazines, so-called resin vulcanizing agents, and oxime vulcanizing agents. Examples include sulfur chemicals. Examples of organic peroxides include dicumyl peroxide, kyumene hydroperoxide, 2,5-
Examples include dimethyl-2,5-di-(tert-butylperoxy)hexane, di-tert-butyl peroxide, benzoyl peroxide, and the like. Examples of sulfur donor compounds include tetramethylthiuram disulfide and pentamethylene tetrasulfide. Examples of sulfur compound promoters include thiazoles such as 2-mercaptobenzothiazole and dibenzothiazole, and 2-cyclohexylbenzothiazyl sulfide. Examples include mercaptoimidazolines such as phenamide, thiocarbamates such as dimethylthiocarbamic acid, and xanthates such as zinc isopropylxanthate. Examples of accelerators used in combination with sulfur or sulfur-based compounds include guanidines such as diphenylguanidine and amines such as hexamethylenetetramine. Examples of mercaptotriazines include dibutylamino-3,5
- Dimercaptotriazine may be mentioned. Examples of resin vulcanizing agents include alkylphenol formaldehyde resins, and oxime vulcanizing agents include p-quinone dioxime and pp'-dibenzylquinone dioxime. Further, when the comonomer component of the copolymer in the composition of the present invention is a halogen-containing epoxide, examples of the vulcanizing agent include polyamines, thioureas, mercaptotriazines, polyphenols, and the like. Specific examples of polyamine vulcanizing agents include hexamethylene diamine carbamate, specific examples of thioureas include ethylene thiourea, dibutylthiourea, and specific examples of mercaptotriazines include trimercaptotriazine, dibutylamino-3,5-triazine, etc. can be mentioned. When mixing rubbers that do not have the above-mentioned functional groups, such as ethylene-propylene rubber, silicone rubber, etc., a vulcanization method using an organic peroxide can be employed for appropriate blending. These vulcanizing agents are used in combination with vulcanization aids as appropriate according to known techniques in the art. These vulcanizing agents and vulcanization aids blended into the composition of the present invention are 0.01 to 20% by weight, usually 0.1 to 20% by weight, based on the polymer components.
Used in a range of 15% by weight. These amounts are arbitrarily determined depending on the composition of the polymer, the type of drug, the purpose of the molded product, etc. Furthermore, the composition of the present invention may optionally contain various reinforcing agents, fillers, plasticizers, processing aids, stabilizers, anti-aging agents, pigments, flame retardants, etc. necessary for processing or for adjusting various physical properties in practical use. Can be combined with Furthermore, various processing methods used in the technical field can be used in the production and processing of the composition of the present invention. As described above, the composition of the present invention can be easily vulcanized using a common vulcanizing agent, and the resulting vulcanizate has the following characteristics. It has extremely good oil resistance against various oils, as well as cold and heat resistance, giving it an excellent balance of performance as a rubber. It also has excellent resistance to rancid oils. Corrosion to metals is improved compared to conventional halogen-containing rubbers. Compared to fluororubber, it has comparable lubricating oil resistance and engine oil resistance, has significantly improved cold resistance, and is economically inexpensive. The effects of the composition of the present invention will be explained below using Examples and Comparative Examples. The formulations in the table are parts by weight. Examples 1 to 14, Comparative Examples 1 to 6 Each compound shown in Table 1 was kneaded with a 6-inch roll at a roll temperature of 60°C, and then pressure-molded at 160°C for 20 minutes. Physical property tests were conducted. The results are shown in Table 2.

【table】

【table】

【table】

【table】

[Table] From the above test results, the vulcanized composition of the present invention is NBR
(Comparative example 1), epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber (comparative example 2), epichlorohydrin-ethylene oxide copolymer rubber (comparative example 3), epichlorohydrin rubber (comparative example 4), acrylic rubber (comparative example 5) )
It has superior oil resistance compared to , and it can be seen that it has a good balance between cold resistance and heat resistance. Fluororubber (Comparative Example 6) is excellent in other properties, but poor in cold resistance. Further, a comparison between Examples 6 and 7 and Comparative Examples 1 and 2 shows that when the products of the present invention are mixed with nitrile rubber or epichlorohydrin rubber, the oil resistance of these rubbers is improved. Corrosion test Each of the vulcanizates of Examples 1, 8 to 11 and Comparative Examples 3 and 4 was sandwiched between two metal plates and left to stand in an atmosphere of 100% relative humidity and 50°C for 120 hours, then taken out and rubber pieces The degree of corrosion of the metal plate left behind was evaluated using the following classes.
The results are shown in Table 3. However, the steel plate is JIS G314
(SPCC), and the aluminum plate used was JIS H4000 (A505 2p).

【table】

[Table] The vulcanized composition of the present invention has significantly improved metal corrosion resistance compared to epichlorohydrin rubber.

Claims (1)

[Scope of Claims] 1 The main chain structure includes 10 mol% or more of the structural units represented by the following formula (), and 1 mol% or more of the structural units represented by the formula () and/or the structural units represented by the formula (). The reduced viscosity measured in 0.1% monochlorobenzene solution at 80℃ is 0.8.
An oil-resistant rubber composition comprising the copolymer described above and a vulcanizing agent for the copolymer. (However, in the formula (), R represents a saturated alkyl group having 1 to 4 carbon atoms). (However, in the formula (), Y represents an allyloxy group, an acryloxy group, a methacryloxy group, or a sorboxy group). (However, in the formula (), X represents a chlorine atom, a bromine atom, or a chloroacetoxy group).