JPH07188463A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber compsn. for a fender which has excellent weatherability, rubber elasticity, and impact resistance and can be colored in various colors. CONSTITUTION:An ethylene-propylene rubber and a natural rubber are compounded pref. in a ratio of (20/80)-(40/60). EPDM is the most suitable as the former rubber.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition for a fender.

[0002]

2. Description of the Related Art Conventionally, carbon black reinforced materials (so-called black products) have been widely used as fenders by utilizing the excellent rubber elasticity of natural rubber, but in recent years, only black products have been used. Not only that, but the needs of colorful objects are increasing. However, the non-carbon black reinforced type (so-called color type) has poor weather resistance and has not yet been put to practical use. That is, those made of natural rubber and styrene-butadiene rubber have poor weather resistance, and the coating film is likely to be peeled off at the time of collision when coating is performed. The chloroprene rubber type has a problem in cost and is inferior in abrasion resistance. It is difficult to balance impact resistance and resilience with a polyolefin resin.

[0003]

SUMMARY OF THE INVENTION The present invention is to provide a rubber composition for a color fender that is excellent in weather resistance, rubber elasticity and impact resistance.

[0004]

That is, the present invention has led to finding a rubber composition for a color fender that contains an ethylene-propylene elastic copolymer and a natural rubber component. The preferable compounding ratio of both is 20 to 40% by weight of the ethylene-propylene elastic copolymer and 60 to 80% by weight of the natural rubber. When the ethylene-propylene elastic copolymer is 20% by weight or less, the weather resistance is deteriorated, and when it is 40% by weight or more, the tensile strength and the tensile elongation are decreased, which is not preferable. The ethylene-propylene-based elastic copolymer preferably has an ethylene content of 50 to 85% by weight, and for example, EPDM (ethylene-propylene-diene methylene rubber) can be selectively used.
Natural rubber can be used as it is.

The steps for obtaining a fender product using the rubber composition of the present invention are as follows: raw material natural rubber and, for example, EPDM, as a compounding material, a reinforcing material, paraffin oil, an auxiliary agent (vulcanization Agents, colorants, etc.), and put them in a closed kneader to knead them to form a compound. Next, this is passed through a roll or the like to form a sheet having a predetermined thickness. The sheet thus obtained is vulcanized at a predetermined temperature and time using a mold or the like, and molded into a fender having a predetermined shape to obtain a product.

[0006]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Table 1-1 (Examples 1 to 4),
The results of measuring various physical properties of various materials having the compositions shown in Table 1-2 (Comparative Examples 1 and 2) and Table 2-2 (Comparative Examples 3 to 5) are shown in Table 2-1 (Example 1). ~ 4) and Table 2-2 (Comparative Examples 1 to 5). The physical properties required as a fender are generally tensile strength of 180 or more, tensile elongation of 400 or more, tear strength of 50 or more, hardness of 72 or less, wear resistance of 0.2 or less, and permanent elongation of It is preferably 15 or less, and the weather resistance is such that cracks do not occur in the test here (circle mark). Those with cracks are marked with x. As is clear from the above results,
The example has all the physical properties necessary for the fender, but the comparative example lacks any of them.

[0007]

[Table 1]

[0008]

[Table 2]

[0009]

[Table 3]

[0010]

[Table 4]

[0011]

The rubber composition of the present invention is excellent in weather resistance, rubber elasticity, and impact resistance, and can be applied with various colors, so that it can meet the demand of consumers as a fender.

Claims (3)

[Claims] 1. A rubber composition for a fender, comprising an ethylene-propylene elastic copolymer and a natural rubber component. 2. The rubber composition according to claim 1, wherein the elastic copolymer of ethylene-propylene is 20 to 40% by weight and the natural rubber is 60 to 80% by weight. 3. The rubber composition according to claim 1, wherein the ethylene-propylene elastic copolymer is EPDM.