JPH0819264B2 - Vulcanizable rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Use) The present invention relates to a vulcanizable rubber composition, and more particularly to a vulcanizable rubber composition having excellent strength properties.

(Prior Art and Problems to be Solved by the Invention) A rubber having excellent strength can be obtained by mixing zinc dimethacrylate and / or basic zinc methacrylate with rubber and crosslinking with organic peroxide. It has been known since ancient times.

That is, JP-A-53-125139 discloses a solid golf ball produced by mixing polybutadiene with methacrylic acid, zinc oxide, and t-butylperoxybenzoate and vulcanizing the mixture.

JP-A-52-121653 discloses that polybutadiene and methacrylic acid are mixed and then zinc oxide is mixed to obtain a composition having excellent abrasion resistance. Furthermore, JP-A-53-8584
No. 2 discloses that a compound having excellent tensile strength can be obtained by adding a non-polymerizable carboxylic acid to a mixture of a diene rubber, methacrylic acid, zinc oxide and an organic peroxide.

However, these vulcanized rubber compositions have a tensile strength of 30%.
Since it is 0 kg / cm ² or less, it cannot be said that the physical properties are satisfactory.

The present inventors have examined the strength characteristics of a vulcanizable rubber composition in which rubber is mixed with methacrylic acid, a zinc compound, and an organic peroxide. As a result, the zinc compound does not contain coarse particles, and the rubber has an appropriate polarity. Then, they found that it was necessary to have radical reactivity, and completed the present invention.

(Means for Solving Problems) An object of the present invention is to provide a vulcanizable rubber composition having excellent strength characteristics. For this purpose, (a) 100 parts by weight of an ethylenically unsaturated nitrile-conjugated diene copolymer rubber, (b) 10 to 60 parts by weight of a zinc compound having 5% or less of coarse particles of 20 μ or more, (c) methacrylic acid 20 -60 parts by weight, and (d) 0.2-10 parts by weight of an organic peroxide are blended to achieve a vulcanizable rubber composition. Another object of the present invention is to provide a method for producing a vulcanizable rubber composition having excellent strength characteristics. This object is achieved by uniformly mixing a zinc compound into an ethylenically unsaturated nitrile-conjugated diene copolymer rubber, then mixing methacrylic acid to form zinc methacrylate, and then blending an organic peroxide. It

(Detailed description of constitution) Ethylenically unsaturated nitrile-conjugated diene copolymer rubber used in the present invention, ethylenically unsaturated nitrile such as acrylonitrile, methacrylonitrile, and 1,3-butadiene, isoprene, 1,3 -Copolymer rubbers with conjugated dienes such as pentadiene and / or monomers copolymerizable with the above two monomers, eg vinyl aromatic compounds,
(Meth) acrylic acid, alkyl (meth) acrylate,
It is a multi-component copolymer rubber with alkoxyalkyl (meth) acrylate, cyanoalkyl (meth) acrylate and the like. These rubbers contain 30 to 60% by weight of ethylenically unsaturated nitrile monomer units and 31% by weight or more of conjugated diene units.

The zinc compounds such as zinc oxide and zinc carbonate used in the present invention are preferably those from which coarse particles have been removed, that is, those which do not contain coarse particles of 20 μm or more by an air classifier or the like. The amount of these zinc compounds used is 10 to 60 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of rubber.

The amount of methacrylic acid used in the present invention is 20 to 60 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of rubber.

The weight ratio of the zinc compound and methacrylic acid used in the present invention can be changed in the range of 0.5 / 1 to 3/1.

The organic peroxide used in the present invention may be any one used in ordinary rubber peroxide vulcanization. For example, dicumyl peroxide, di-t-butyl peroxide,
t-butyl cumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane , 2,5-dimethyl-2,5-mono (t-butylperoxy) -hexane, α, α′-bis (t-butylperoxy-m-isopropyl) benzene and the like. One or two of these organic peroxides are used.
Although more than one kind is used, it is usually used in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of rubber, but it is desirable to appropriately determine the optimum amount according to the required physical property values.

The vulcanizable rubber composition of the present invention may be produced by any method as long as a good dispersion of the zinc compound can be obtained, in advance, by adding the zinc compound to the rubber, a roll usually used in the rubber industry, It is preferable to employ a method in which methacrylic acid is mixed or absorbed after a good dispersion of the zinc compound is obtained by mixing well with Banbury, a kneader or the like. Then, an organic peroxide is added and mixed uniformly to obtain the vulcanizable rubber composition of the present invention.

In the vulcanizable rubber composition of the present invention, in addition, carbon black, reinforcing agents such as silica, fillers such as carbon charcoal, talc, triallyl isocyanurate, trimethylolpropane triacrylate, m-phenylene bismaleimide, etc. Various chemicals usually used in the rubber industry such as a crosslinking aid, a plasticizer, a stabilizer, a processing aid, and a coloring agent can be appropriately mixed and used as necessary.

(Effect) Thus, according to the present invention, it is possible to obtain a rubber vulcanizate having excellent strength characteristics as compared with the prior art. Therefore, the vulcanizable rubber composition of the present invention is useful for producing hoses, rolls, anti-vibration rubber and the like.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. Parts and% in Examples and Comparative Examples are indicated on a weight basis unless otherwise specified. In addition, as a mixing method, the compounding agents shown in the table were sequentially added and mixed by rolls while visually confirming that they were sufficiently dispersed. The mixture was aged overnight to obtain a vulcanizable rubber composition.

Example 1 A vulcanizable rubber composition was prepared according to the formulation shown in Table 1. A vulcanized sheet having a thickness of 2 mm was prepared by press vulcanization under the vulcanization conditions shown in the table, and vulcanized physical properties were measured according to JIS K 6301. The obtained results are shown in Table 1.

Example 2 A vulcanizable rubber composition was prepared according to the formulation shown in Table 2. Vulcanization properties were measured in the same manner as in Example 1 by press-vulcanizing under the vulcanization conditions shown in the table to obtain a vulcanized product. The results obtained are shown in Table 2.

Claims (3)

[Claims] 1. A zinc compound 10 comprising (a) 100 parts by weight of an ethylenically unsaturated nitrile-conjugated diene copolymer rubber, and (b) 5% or less of coarse particles of 20 μ or more.
-60 parts by weight, (c) 20 to 60 parts by weight of methacrylic acid, and (d) 0.2 to 10 parts by weight of organic peroxide are compounded. 2. The molar ratio of methacrylic acid and zinc compound is 1/0.
The vulcanizable rubber composition according to claim 1, which is 5 to 1/3. 3. An ethylenically unsaturated nitrile-conjugated diene copolymer rubber is uniformly mixed with a zinc compound, and then methacrylic acid is mixed to form zinc methacrylate, and then an organic peroxide is blended. The method for producing the vulcanizable rubber composition according to claim 1 or 2.