JPH0778149B2 - Vulcanizable rubber composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vulcanizable rubber composition, and more particularly to a vulcanizable rubber composition having excellent strength characteristics.

(Problems to be Solved by Prior Art and Invention) Amorphous rubber is generally used by adding a reinforcing agent such as carbon black or silica to give it strength and hardness for practical use. In order to obtain a rubber having even higher strength, it is necessary to mix a reinforcing agent having an average particle size of several tens of μm or less, but the rubber mixed with these fine particle reinforcing agents has a high viscosity and causes various problems in processability. In addition, the obtained vulcanized rubber has the drawbacks of low impact resilience and high dynamic exothermicity.

Further, urethane rubber is often used in applications requiring high strength, but urethane rubber has a problem in heat resistance.

Rubber with excellent strength properties is required for various applications,
Conventionally, the following techniques are known.

Japanese Unexamined Patent Publication No. 53-125139 discloses a solid golf ball made by mixing methacrylic acid, zinc oxide, and t-butylperoxybenzoate with polybutadiene 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-53-85842
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, in these patents there is no recognition of ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber.

As a result of diligent studies on the effect of a mixture of zinc methacrylate and an organic peroxide on the strength properties of various rubbers, the present inventors have found that ethylenically unsaturated nitriles and conjugated diene-based highly saturated rubbers have zinc compounds and methacrylic acid. Further, they have found that a vulcanized product obtained by blending an organic peroxide has extremely high strength properties as compared with a conventional rubber, and completed the present invention.

(Means for Solving the Problems) An object of the present invention is to provide an ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber having a content of conjugated diene units in a polymer chain of 30% by weight or less with zinc oxide and carbonic acid. It is achieved by using a vulcanizable rubber composition containing a zinc compound such as zinc, methacrylic acid, and an organic peroxide.

(Detailed Description of Structure) The ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber used in the present invention is an ethylenically unsaturated nitrile such as acrylonitrile or methacrylonitrile, and 1,3-butadiene, isoprene, 1,3 -Copolymers with conjugated dienes such as pentadiene, monomers copolymerizable with the above-mentioned two types of monomers, for example, vinyl aromatic compounds, (meth) acrylic acid, alkyl (meth) acrylate, alkoxyalkyl A multi-component copolymer with (meth) acrylate, cyanoalkyl (meth) acrylate, etc., and specifically, acrylonitrile-butadiene copolymer rubber, acrylonitrile-isoprene copolymer rubber, acrylonitrile-butadiene-isoprene copolymer rubber, acrylonitrile -Butadiene-acrylate copolymer rubber, acrylonitrile - butadiene - acrylate - can be mentioned methacrylic acid copolymer rubber.

These rubbers contain 30 to 30 ethylenically unsaturated nitrile units.
The content of the conjugated diene unit is 30% by weight or less, preferably 20% by weight or less by means such as partial hydrogenation of the conjugated diene unit.

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 usually 5 to 80 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of rubber.

The amount of methacrylic acid used in the present invention is usually 10 to 70 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of rubber.

The molar 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)
Hexine-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t-butylperoxy) -hexane, α, α'- Examples thereof include bis (t-butylperoxy-m-isopropyl) benzene. These organic peroxides are used alone or in combination of two or more and are usually used in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of rubber. It is desirable to decide.

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, the zinc compound is added to the rubber, and a roll usually used in the rubber industry, It is preferable to employ a method in which after mixing well with Banbury, a kneader or the like to obtain a good dispersion of the zinc compound, methacrylic acid is mixed or absorbed. After that, 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, carbon black, reinforcing agents such as silica, fillers such as calcium carbonate and 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 and strength characteristics at high temperature as compared with the prior art and having a small dynamic exothermic property. Therefore, the vulcanizable rubber composition of the present invention is useful for the production of hoses, rolls, anti-vibration rubber, rubber for snow chains and tires.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. The parts and% in the examples and comparative examples are shown by weight unless otherwise specified. In addition, mixing was performed by adding the compounding agents shown in the table by a kneader in the order described, except for the organic peroxides, and visually confirming that they were sufficiently dispersed. After aging the mixture for a whole day and night, a vulcanizable rubber composition was obtained by mixing an organic peroxide with a roll.

(Example 1) The amount of acrylonitrile bound to ityl isobutyl ketone was 37.
% Of emulsion polymerized acrylonitrile-butadiene copolymer rubber (hereinafter referred to as NBR) was dissolved and hydrogenated using a pd-carbon catalyst to prepare hydrogenated NBR containing conjugated diene units of B to G shown in Table 1. .

A vulcanizable rubber composition was prepared by using NBR (Table 1A) and these rubbers according to the compounding recipe shown in Table 2. Similarly, press vulcanization was performed under the vulcanization conditions shown in Table 2 to prepare a 2 mm thick vulcanized sheet, and the vulcanized physical properties were measured according to JIS K6301. The results obtained are shown in Table 2. It can be seen that the higher the hydrogenation rate of NBR, the higher the tensile strength.

(Example 2) In the same manner as in Example 1, the emulsion-polymerized NBR having a bound acrylonitrile content of 45% was hydrogenated to obtain hydrogenated NBR as shown in Table 3.
It was created.

Using these rubbers, according to the compounding recipe shown in Table 3,
A vulcanizable rubber composition was prepared. Similarly, press vulcanization was performed under the vulcanization conditions shown in Table 3, and vulcanization physical properties were measured in the same manner as in Example 1. The results are shown in Table 3.

The tensile strength shows the same tendency as in Example 1.

(Example 3) Using the hydrogenated NBR-E prepared in Example 1, various amounts of zinc oxide and methacrylic acid were added to prepare vulcanizable rubber compositions as shown in Table 4. Vulcanization sheet was obtained by press vulcanization under the vulcanization conditions shown in the table, and vulcanization physical properties were measured.
The results are shown in Table 4.

(Example 4) The zinc compounds shown in Table 5 were classified by an air classifier, and the hydrogenated NBR-E of Example 1 was used to prepare a compounded rubber composition according to the compounding recipe shown in Table 5. The vulcanized product was obtained by press vulcanizing under the vulcanizing conditions shown in the table, and the vulcanized physical properties were measured. The results are shown in Table 5.

By classifying the zinc compound to 20 μm or less as described above, the tensile strength can be further improved.

(Example 5) The results of measuring other properties of the composition of the present invention are
It is shown in Table 6. A vulcanizable rubber composition was prepared according to the formulation shown in the same table, press-vulcanized under the vulcanization conditions shown in the same table to obtain a vulcanized product, and vulcanized physical properties were measured.

Claims (2)

[Claims] 1. The content of conjugated diene units in the polymer chain is 20.
To 100 parts by weight of ethylenically unsaturated nitrile-conjugated diene-based highly saturated rubber of not more than 10% by weight, 5 to 80 parts by weight of a zinc compound having a particle diameter of 20 μ or less, 10 to 70 parts by weight of methacrylic acid and 0.2 of an organic peroxide. A vulcanizable rubber composition characterized by being mixed in an amount of up to 10 parts by weight. 2. The vulcanizable rubber composition according to claim 1, wherein the highly saturated rubber is a hydrogenated product of an ethylenically unsaturated nitrile-conjugated diene copolymer.