JPH078932B2 - Rubber mixture with good oil resistance - Google Patents

Description

The present invention relates to an acrylonitrile rubber-butadiene copolymer rubber which is excellent in oil resistance, cold resistance, heat resistance and the like and which is particularly useful under contact with alcohol-blended gasoline. And an alkylene sulfide-epihalohydrin copolymer rubber.

(Prior art) Satisfaction of heat resistance, gasoline (oil) resistance, and cold resistance at the same time by improving engines due to emission regulations of passenger cars that came into effect as a result of social demands for improving atmospheric environment in recent years. Many important safety parts using synthetic rubber have been newly adopted and installed in passenger cars. Of the existing synthetic rubbers, acrylonitrile-butadiene copolymer rubber (hereinafter sometimes referred to as NBR) is an excellent synthetic rubber with well-balanced properties and is widely used in applications such as hoses, gaskets, O-rings and oil seals. It is used.

However, in recent years, as part of the development of alternative energy sources for petroleum worldwide, the use of a mixture of gasoline and alcohols such as ethanol and methanol has been studied, and it has already reached the stage of practical application. However, when such alcohol-blended gasoline is used as an automobile fuel, it has a great influence on the rubber material, and the swelling of NBR which has been conventionally used is increased, and it is difficult to use it as an automobile part. Especially in the case of methanol-blended gasoline, the effect is extremely large and the swelling increases remarkably. Therefore, when parts made of NBR are mounted on a passenger car, there is a risk that the function cannot be maintained for a long period of time.

(Problems to be solved by the invention) Therefore, an object of the present invention is to improve alcohol resistance to gasoline blending without sacrificing heat resistance, gasoline (oil) resistance and cold resistance possessed by NBR. An object is to provide an oil resistant rubber composition.

(Means for Solving Problems) This object of the present invention is to provide NBR 101 to 80% by weight, alkylene sulfide 15 to 70% by mole, epihalohydrin 30 to 85% by mole.
Copolymer rubber containing 0 to 15 mol% of unsaturated epoxide
Achieved by a rubber mixture, characterized in that it consists of 90 to 20% by weight.

The NBR used in the present invention is a copolymer rubber containing 25 to 60% by weight of acrylonitrile, preferably 35 to 55% by weight, and 75 to 40% by weight of butadiene, preferably 65 to 45% by weight. If the acrylonitrile content is less than 25% by weight, the oil resistance is poor, while 60%
If it exceeds 5% by weight, there is a problem in cold resistance. If desired, α, β-monoethylenically unsaturated carboxylic acid ester such as butyl acrylate or methoxyethyl acrylate may be further added as a copolymerization component in an amount of 0 to 50% by weight in the copolymer rubber.
It can have in the range of. NB in the present invention
R may be hydrogenated from the above rubber.

The alkylene sulfide in the alkylene sulfide-epihalohydrin-unsaturated epoxide copolymer rubber used in the present invention means such as epithiofluorohydrin, epithiochlorohydrin, epithiobromohydrin or epithiophoyohydrin. Epithiohalohydrin, ethylene sulfide, propylene sulfide, butene sulfide, isobutylene sulfide, cyclohexene sulfide, styrene sulfide, p-chlorostyrene sulfide, p-chloromethyl styrene sulfide, Methyl thioglycidyl ether, ethyl thioglycidyl ether,
Examples thereof include allyl thioglycidyl ether, phenyl thioglycidyl ether, methyl thioglycidyl thioether, allyl thioglycidyl thioether, phenyl thioglycidyl thioether, thioglycidyl (meth) acrylate, and γ-thioglycidyloxypropyltrimethoxysilane. Of these, epithiochlorohydrin, ethylene sulfide, and methylthioglycidyl ether are particularly preferable.

The epihalohydrin in the copolymer rubber is selected from epifluorohydrin, epichlorohydrin, epibromohydrin and epiiodohydrin, preferably epichlorohydrin.

Examples of unsaturated epoxides include epoxide compounds having a carbon-carbon unsaturated double bond such as butadiene monoxide, allyl glycidyl ether, and glycidyl (meth) acrylate.

The composition of the copolymer rubber in the present invention has an alkylene sulfide of 15 to 70 mol%, preferably 20 to 50 mol%, shrimphalohydrin of 30 to 85 mol%, preferably 40 to 80 mol%, and an unsaturated epoxide of 0 to 15 mol%, preferably 0. ~ 0 mol%.
If the alkylene sulfide content is less than 15 mol%, no improvement in oil resistance, cold resistance, or other performance is observed, while if it exceeds 70 mol%, heat resistance or other performance is impaired. The unsaturated epoxide may be contained as necessary, and especially in a copolymer rubber having a low alkylene sulfide content, the introduction of the unsaturated epoxide can improve cold resistance, performance such as swelling in alcohol-mixed sour gasoline. it can.
However, if the unsaturated epoxide exceeds 15 mol%, the balance of performance will be impaired. The copolymer of the present invention may further contain an alkylene oxide such as ethylene oxide or propylene oxide as a copolymerization component in the range of 0 to 50 mol% in the copolymer, if desired.

In the mixing of NBR and copolymer rubber in the present invention, NBR
The ratio of 10 to 80 depends on the performance required for the rubber molded product.
It is appropriately determined within the range of weight%. If it exceeds 80% by weight, the resistance to gasoline blended with alcohol deteriorates, and if it is less than 10% by weight, cold resistance becomes a problem.

The vulcanizing agent of the NBR of the present invention may be a sulfur-based vulcanizing agent that is usually used for diene rubbers, and sulfur and sulfur such as morpholine disulfide, tetramethylthiuram disulfide, and thiuram compounds and polymer polysulfides. A donor is mentioned.

As the vulcanizing agent for the copolymer rubber of the present invention, a polythiol-based vulcanizing agent that causes a vulcanizing reaction via a halogen atom,
A thiourea-based 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.

The polythiol-based vulcanizing agent may be a polythiol-based vulcanizing agent usually used in epichlorohydrin-based rubbers, such as di- or trithiol-S-triazine compounds (for example, described in JP-B-48-36926), 2,5-dimercapto. -1,
3,4-thiadiazole compounds (e.g. U.S. Pat. No. 4,288,5
76), 2,3-dimercaptopyrazine compounds (for example, described in JP-B-58-14468), 2,3-dimercaptoquinoxaline compounds (for example, described in JP-B-58-14469), 3,5- Examples thereof include dimercapto-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).

As the sulfur-based vulcanizing agent, the vulcanizing agent used in NBR can be used.

The amount of the vulcanizing agent used is 0.1 to 10 parts by weight per 100 parts by weight of the mixture of NBR and copolymer rubber. It is of course possible to use a vulcanizing agent together.

The rubber composition of the present invention is a mixture of NBR, an alkylene sulfide, an epihalohydrin, and a rubber obtained by copolymerizing an unsaturated epoxide, if necessary, a vulcanizing agent and, if necessary, a vulcanization accelerator, a vulcanization aid, and a reinforcing agent. It is prepared by mixing conventional rubber compounds such as 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.

(Effects of the Invention) The obtained rubber vulcanizate is particularly suitable for fuel hoses, seals, gaskets, O-rings, diaphragms, etc. of automobiles, as well as alcohol resistance mixed gasoline resistance, oil resistance,
It shows an excellent balance of physical properties such as cold resistance and heat resistance.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. Parts and% in the examples are based on weight unless otherwise specified.

Example 1 An ethylene sulfide-epichlorohydrin copolymer rubber prepared by a known solution polymerization method using an organoaluminum compound-based polymerization catalyst and NBR were mixed with other compounding agents on a cooling roll according to the following compounding recipe, A vulcanized product was prepared by heating at 160 ° C for 30 minutes.

Formulation NBR ^{* 1} 50 Ethylene sulfide-epichlorohydrin copolymer rubber 50
Stearic acid 2 FEF Carbon 35 Zinc oxide 2.5 Lead oxide 2.5 Sulfur 0.25 Tetramethylthiuram disulfide 0.5 Cyclohexylbenzothiazyl sulfenamide 0.5 2-Mercaptoimidazoline 0.6 N-phenyl-N'-isopropyl-p-phenylenediamine 0.5 Nickel dibutyldithiocarbamate 0.5 * 1 Nipol DN-101L, a product of Zeon Corporation (Acrylonitrile content 42% by weight) Next, the physical properties of the vulcanizate were measured by JIS K-6301. The results are shown in Table 1.

From the table, it can be seen that the rubber mixture of the present invention gives a vulcanizate having well-balanced properties.

Example 2 A copolymer rubber of NBR and ethylene sulfide (39 mol%)-epichlorohydrin (58 mol%)-allyl glycidyl ether (3 mol%) was cooled together with other compounding agents according to the compounding recipe of Table 2, respectively. The mixture was mixed with a roll, and the obtained mixture was prepared with a cooling roll at a mixing ratio shown in Table 3.

The physical properties of the vulcanizate obtained in the same manner as in Example 1 are shown in Table 3 below.

Example 3 NBR and a copolymer rubber of ethylene sulfide (40 mol%)-epichlorohydrin (60 mol%) were mixed with other compounding agents on a cooling roll according to the compounding recipe of Table 4, and the obtained compounding was obtained. A mixture was prepared with a cooling roll at the compounding ratio shown in Table 5.

The physical properties of the vulcanizate obtained in the same manner as in Example 1 are shown in Table 5 below.

Example 4 A copolymer rubber of hydrogenated NBR and ethylene sulfide (35 mol%)-epichlorohydrin (62 mol%)-allyl glycidyl ether (3 mol%) was added to each other according to the compounding recipe shown in Table 6. The mixture was mixed with the agent on a chill roll, and the obtained mixture was prepared on a chill roll at a blending ratio shown in Table 7.

The physical properties of the vulcanizate obtained in the same manner as in Example 1 are shown in Table 7 below.

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Claims (1)

[Claims] 1. An acrylonitrile-butadiene copolymer rubber
10-80% by weight, alkylene sulfide 15-70 mol%, epihalohydrin 85-30 mol% and unsaturated epoxide 0-
A rubber mixture having a good oil resistance, which comprises 90 to 20% by weight of a copolymer rubber of 15 mol%.