JPH044242A - Formed rubber article having anisotropic strength - Google Patents

Abstract

PURPOSE:To obtain a formed rubber article having anisotropic strength at a low cost by kneading a rubber composition containing a base rubber, short fibers, an alpha,beta-unsaturated fatty acid metal salt and an organic peroxide under application of a shearing force in a definite direction and vulcanizing the product. CONSTITUTION:The objective formed rubber article can be produced by kneading a rubber composition containing (A) 100 pts.wt. of a base rubber selected from isoprene rubber, natural rubber, butadiene rubber, styrene- butadiene rubber, nitrile rubber, ethylene-propylene rubber, chloroprene rubber and butyl rubber, (B) 3-100 pts.wt. of short fibers, preferably nylon fiber, etc., having a length of >=1mm and a thickness of >=5d, (C) 3-100 pts.wt. of a metal salt (preferably Zn salt or Mg salt) of an alpha,beta-unsaturated fatty acid (preferably 3-8C fatty acid) and (D) 0.5-5 pts.wt. of an organic peroxide (preferably dicumyl peroxide) under application of a shearing force in definite direction and vulcanizing the kneaded mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rubber molded article having anisotropy in strength, having high strength in a certain direction and not having high strength in a different direction.

(Prior art) In recent years, demands for functional materials have become more sophisticated, and rubber materials that have the elasticity of rubber and anisotropy in strength are required for various mechanical parts, sporting goods, and industrial products such as various hoses. It is becoming more and more common.

Up to now, in order to impart strength anisotropy to rubber molded products, fibers (for example, short fibers) and fillers have been oriented in a certain direction during mixing. Although this method of incorporating other orientation-imparting agents, especially short fibers, satisfies the conventional requirements, it is not necessarily a suitable method when higher strength anisotropy is required. . If higher anisotropy is required, the amount of short fibers may be increased, but this greatly impairs moldability and other properties.

(Problems to be Solved by the Invention) The present invention improves the technique using short fibers from the viewpoint of rubber composition, and provides a higher strength anisotropy than before without increasing the amount of short fibers too much. The goal is to provide technology.

(Means for Solving the Problems) The present invention provides a base rubber 100% by weight selected from the group consisting of isoprene rubber, natural rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, chloroprene rubber, and butyl rubber. part, short fiber 3 to 100 parts by weight, σ, β-unsaturated fatty acid metal salt 3 to
After kneading a rubber composition containing 100 parts by weight and 0.5 to 5.0 parts by weight of an organic peroxide by applying shear force in a certain direction,
A rubber molded product having anisotropy in strength obtained by vulcanization is provided.

The base rubber of the present invention is selected from the group consisting of all rubber components conventionally used in rubber compositions, isoprene rubber, natural rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, chloroprene rubber and butyl rubber. . Particularly preferable base rubber is c
is-1,4-polybutadiene with a cis structure of 90% or more.

The short fibers used in the present invention include carbon fibers, alumina fibers, aromatic polyamide fibers, silicon carbide fibers, silica fibers, poron fibers, potassium titanate fibers, polyamide fibers, polyester fibers, polyhinyl alcohol fibers, polyacrylic fibers, and polyamide fibers. General synthetic fibers or natural fibers such as vinyl chloride fiber, polyvinylidene chloride fiber, polyethylene fiber, polypropylene fiber, polyurea fiber, etc.
It is even better if these fibers are subjected to heat stretching treatment and adhesion treatment to give them strength.

Preferred are polyamide (especially nylon) fibers.

The length of the short fibers is 1/7111 or more, preferably 30 mm or less, and the thickness is ld (denier) or more. In particular, it is preferable to have a length of 1+nm or more and a thickness of 5d or more. The amount of short fibers added to the rubber composition is 100% of the base rubber.
3 to 100 parts by weight, preferably 10 to 5 parts by weight
It is 0 parts by weight. If it is less than 10 parts by weight, the anisotropy of strength will be insufficient, and if it exceeds 100 parts by weight, problems will occur in moldability, etc.

As the metal salt of the a,β-unsaturated fatty acid used in the present invention, a metal salt of a,β-monoethylenically unsaturated carboxylic acid having 3 to 8 carbon atoms is suitable, and examples of such salts include: Examples include metal salts of methacrylic acid, acrylic acid, itaconic acid, crotonic acid, and the like. The metal is generally a divalent metal, preferably zinc, magnesium, etc., but other metals such as sodium, lithium,
Aluminum or the like may also be used. The blending amount of the metal salt of α,β-unsaturated fatty acid is 3 to 3 to 100 parts by weight of the base rubber.
The amount is 100 parts by weight, preferably 10 to 70 parts by weight. 3
If the amount is less than parts by weight, anisotropy in strength will not be obtained and the desired effect will not be achieved. If it exceeds 100 parts by weight, the compound will become hard and workability will deteriorate. In addition, moldability is also poor. Rather than as a metal salt, this component may be combined with the α,β-unsaturated fatty acid as a metal oxide, hydroxide or carbonate to form a salt in the rubber composition.

Examples of the organic peroxide to be blended into the rubber composition of the present invention include perbenzoic acid, benzoyl peroxide, cumene peroxide, and dicumyl peroxide.

Preferred is dicumyl peroxide. The amount of organic peroxide blended is 0.5 to 5.0 parts per 100 parts by weight of the base rubber.
Parts by weight. If it is less than 0.5 parts by weight, crosslinking of the metal salt of α,β-unsaturated fatty acid is difficult to occur, and if it exceeds 5.0 parts by weight, the molded product becomes brittle and is not practical. The amount of organic peroxide blended is 1.0 to 3.0 parts by weight per 100 parts by weight of the base rubber.
0 parts by weight is preferred.

It is generally known that metal salts of α,β-unsaturated fatty acids co-crosslink with rubber to provide high hardness and high durability. Surprisingly, in the present invention, when the crystals of the metal salt of a, β-unsaturated fatty acid are kneaded into the rubber composition, it is found that the crystals are largely oriented in the grain direction of the rubber when irradiated with X-rays. I realized that. Therefore, the present inventors have developed short fibers and a, β
- If a rubber composition prepared by blending a metal salt of an unsaturated fatty acid and kneading it by applying shearing force in a certain direction is vulcanized in a mold as it is, the rubber composition will move in the grain direction of the rubber even without blending a large amount of short fibers. It has been found that a rubber molded article having high strength but not so high strength can be obtained in a direction different from the above direction, particularly in a direction making 90° to the orientation direction. The method of kneading the rubber composition under shearing force to obtain the rubber molded product of the present invention is not particularly limited. The extrusion direction is the same as the orientation direction. Furthermore, according to the research of the present inventors, the rubber molded product of the present invention shows high orientation not only in strength but also in elongation.Similar to the strength orientation, it does not elongate much in the orientation direction, but has a high degree of orientation in other directions. was found to grow significantly.

The rubber molded product of the present invention can be made into a rubber molded product with different properties by integrally molding a plurality of unvulcanized rubber compositions oriented in one direction or in combination in different orientation directions. Molding (vulcanization) is performed under conventionally known conditions.

-For boat fishing, the temperature is 10-40℃ in the mold.
It is carried out for minutes.

The rubber molded product of the present invention can be used as a sole for sports shoes (by molding a sole with high strength in the lateral direction, a sole that is strong in the left and right directions and has elasticity in bending can be obtained. A hose that has high strength and is flexible against bending can be obtained.It is also suitably used for timing belts, chains, rubber springs, etc.

(Effects of the Invention) According to the present invention, a rubber molded article having high strength and anisotropy, which could not be obtained by conventional short fiber blending methods, can be obtained. This rubber molded product is very inexpensive and has high strength.

(Example) The present invention will be explained in more detail with reference to Examples. The present invention should not be construed as being limited to these examples.

Examples 1 to 4 and Comparative Example 1.2 The ingredients shown in Table 1 were kneaded with a roll by applying shearing force in the circumferential direction. The obtained rubber composition was molded into a plate (about 2 mm thick) at 160° C. for 30 minutes.

Claims (1)

[Claims] 1. 100 parts by weight of base rubber selected from the group consisting of isoprene rubber, natural rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, chloroprene rubber and butyl rubber, 3 to 1 parts by weight of short fibers
00 parts by weight, metal salt of α,β-unsaturated fatty acid 3-100
A rubber composition containing 0.5 to 5.0 parts by weight of an organic peroxide is kneaded by applying shearing force in a certain direction, and then vulcanized to have anisotropic strength. Rubber moldings.