JPH023438A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition which gives a vulcanized material excellent in heat resistance, abrasion resistance, and flexural fatigue resistance by incorporating an organic peroxide and a bismaleimide compound into a blended rubber comprising an acrylic rubber and a hydrogenated NBR. CONSTITUTION:This rubber compound is obtained by incorporating an organic peroxide and a bismaleimide compound into a blended rubber comprising an acrylic rubber and a hydrogenated NBR. The acrylic rubber comprises a polymer of at least one monomer selected from a 1-8C alkyl acrylate and an alkoxy acrylate having both 1-4C alkyl groups and 1-4C alkylene groups, or it may comprise a copolymer of said monomer with a monomer copolymerizable therewith and/or a monomer having crosslinkable groups. The hydrogenarated NBR is one that has a degree of hydrogenation of about 80% or higher, generally somewhat lower than 100% in respect of required heat resistance, cost, etc., although the higher the degree of hydrogenation up to 100%, the higher the heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber composition. More specifically, the present invention relates to a rubber composition that provides a vulcanizate with excellent heat resistance, abrasion resistance, bending fatigue resistance, and oil resistance.

[Conventional technology]

Hydrogenated NOR as a material with improved heat resistance of NBH
However, unless the degree of hydrogenation is 100%, double bonds remain in the molecule, so its heat resistance level is 120 to 130°C. Therefore, hydrogenated NBR is
It is still not said to have sufficient heat resistance, and since it has a tendency to crystallize, its bending fatigue resistance is also poor, and there are also problems with oil resistance at high temperatures.

On the other hand, in the case of acrylic rubber, the heat resistance is
Although it is superior to BR, its mechanical strength is low.
As a result, there was a problem of poor abrasion resistance6 [Problem to be solved by the invention] The object of the present invention is to develop a material that has the characteristics of both acrylic rubber and hydrogenated NBR, that is, has heat resistance, abrasion resistance, The object of the present invention is to provide an inexpensive rubber composition that provides a vulcanizate with excellent bending fatigue resistance and oil resistance.

(Means for Solving the Problems) The object of the present invention is to provide acrylic rubber and hydrogenated N[]
This is achieved by a rubber composition in which an organic peroxide and a bismaleimide compound are blended with rubber blended with R.

The acrylic rubber is at least one selected from the group consisting of alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, and alkoxy acrylates in which the alkyl group and the alkylene group each have 1 to 4 carbon atoms. The acrylate polymer may contain a polymerizable monomer and/or a crosslinkable group-containing monomer that can be copolymerized with these monomers.

A few examples of such acrylate polymers are as follows: Ethyl acrylate-n-butyl acrylate-methoxyethyl acrylate terpolymer n-butyl acrylate-methoxyethyl acrylate copolymer Ethyl acrylate- Hydroxyalkyl acrylate copolymer polyethyl acrylate Hydrogenated NBR with a hydrogenation rate of about 80% or more is used, and the higher the hydrogenation rate up to 100%, the higher the heat resistance. Generally, from the viewpoint of the required degree of heat resistance, cost, etc., those having a hydrogenation rate somewhat lower than 100% are used.

Both acrylic rubber and hydrogenated NBR are about 10 to 90
It is used in a proportion by weight of i%, preferably about 30 to 70% by weight. If acrylic rubber is used in a proportion greater than this, the abrasion resistance will deteriorate, while if hydrogenated N or BR is used in a proportion greater than this, the heat resistance will be reduced.

Both of these blended rubbers are co-crosslinked with an organic peroxide. Examples of organic peroxides include di-tert-butyl peroxide, dicumyl peroxide, di-tert-butylcumyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2 ,5
-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3,1,3-di(tert-butylperoxy) diisopropyl)benzene, 2,5-dimethyl-2
, 5-di(benzoylperoxy)hexane, tert-butylperoxybenzoate-1-, tert-butylperoxyisopropyl carbonate, lobutyl-4°4-di(tert-butylperoxy)valerate, and the like.

Bismaleimide compounds used together with these organic peroxides include, for example, N,N'-m-phenylenebismaleimide-N,N'-P-phenylenebismaleimide, N,N'-m-phenylene (1 -Methyl) bismaleimide, N, N'=2.7-naphthene bismaleimide, N, N'-m-naphthene bismaleimide, N, N'
-m-phenylene-4-methylbismaleimide, N,N
'-m-phenylene(4-ethyl)bismaleimide and the like are used.

The organic peroxide content is approximately 0.0% per 100 parts by weight of blended rubber.
The bismaleimide compound is used in a proportion of 1-10 parts by weight, preferably about 0.5-5 parts by weight, and the bismaleimide compound in a proportion of about 0.1-20 parts by weight, preferably about 0.5-10 parts by weight. If the amount of organic peroxide or bismaleimide is less than this, the crosslinking density will be low and vulcanization molding will not be possible.On the other hand, if the amount is more than this, molding problems such as reversion and foaming may occur. come to arise.

In addition to the above essential ingredients, reinforcing agents such as carbon black and fine silica, fillers such as talc, clay, graphite, and calcium silicate, stearic acid,
Processing aids such as palmitic acid and paraffin wax, and acid acceptors such as zinc oxide.

Compounding agents commonly used in the rubber industry, such as anti-aging agents and plasticizers, can be added as appropriate.

The rubber composition is prepared by kneading it using a kneading machine such as an intermix, a seconder, or a Banbury mixer, or an open roll, and the vulcanization thereof is carried out by
This is generally carried out by heating at about 150 to 200° C. for about 5 to 60 minutes using an injection molding machine, a compression molding machine, a vulcanization press, or the like.

〔Effect of the invention〕

In general, acrylic rubber is mainly vulcanized with amine or soap, and peroxide vulcanization is difficult to perform.On the other hand, hydrogenated NOR is mainly vulcanized with peroxide or sulfur, but there is a bismaleimide between the two. Peroxide-based co-crosslinking is made possible by the coexistence of compounds. Furthermore, since the compatibility between the blended platform polymers is good, it is possible to mix these two without causing microscopic interfacial peeling.

In this way, by co-crosslinking acrylic rubber and Suison-added NOR with an organic peroxide/bismaleimide compound system, properties that cannot be obtained with each rubber alone, such as heat resistance, abrasion resistance, and A material with a good balance of bending fatigue resistance and oil resistance is provided.

The rubber composition of the present invention having such characteristics can be suitably used for molding sealing rubber materials such as oil seals, packings, O-rings, and diaphragms, or industrial rubber materials such as hoses, belts, and rubber rolls.

〔Example〕

Next, the present invention will be explained with reference to examples.

Examples 1 to 2, Comparative Examples 1 to 4 (blank below) J difference example-1” Knee hydrogenated NBR for wood (Nippon Zeon product Zetpol 2020)
FEF carbon black zinc oxide diphenylamine stearic acid After kneading each compounding agent at a blending ratio of 12-inch open roll or higher, hot press molding was performed at 165°C for 30 minutes in a heating oven, and then at 150°C for 1 hour in a heating oven.
Oven vulcanization for 0 hours (1 hour in Comparative Example 4)
A rubber sheet measuring 150 x 150 x 2 mm was molded.

Although Comparative Example 1 had a low crosslinking density and could be molded into a sheet, its rubber strength did not reach practical strength, and Comparative Example 2 was not vulcanized and could not be molded into a rubber sheet.

Examples 1 and 2 and Comparative Example 3 that were molded into rubber sheets
4, in accordance with JIS K-6301,
An air heating aging test and an oil resistance test were conducted, and the hardness change, tensile strength change rate, elongation change rate, and volume change rate (oil resistance test only) were measured.

The results obtained are shown in Table 1 below.

(Space below) Man 1 From the above results, Examples 1 and 2 show well-balanced physical properties in both heat resistance and oil resistance, while Comparative Example 3 has low rubber strength. Moreover, it is shown that the material of Comparative Example 4 has poor heat resistance.

Examples 3-4, Comparative Examples 5-6 Acrylic rubber (PA602) Hydrogenated NBR (Zetpol 2020) 11AF carbon black Zinc oxide diphenylamine stearate Tetrafluoroethylene resin powder (particle size 0.5 μm) Shaped and then heated Oven vulcanization was performed at 150° C. for 8 hours in an oven to produce a 150 x 150 x 2 nm sheet-like test piece and a dematcher bending test piece based on JIS K-630.

These test pieces were subjected to a dematcher bending test in accordance with JIS-6301 and a taper abrasion test in accordance with JIS K-7204 (II-18, IKg, 10
00 times) and obtained the results shown in Table 2 below.

The above-mentioned compounding ratios were kneaded in a 3Q kneader, and heat pressed at 160°C for 20 minutes. From the above results, Examples 3 and 4 had good bending fatigue resistance and wear resistance. On the other hand, it is shown that the material of Comparative Example 5 has poor wear resistance, and the material of Comparative Example 6 has poor bending fatigue resistance.

Claims (1)

[Claims] 1. A rubber composition formed by blending an organic peroxide and a bismaleimide compound with a blend rubber of acrylic rubber and hydrogenated NBR.