JPH0464535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for surface treatment of vulcanized rubber molded articles. More specifically, the present invention relates to a surface treatment method for achieving low friction and non-adhesion on the surface of a vulcanized rubber molded product.

[Conventional technology]

In general, rubber has a high frictional resistance, so molded products made of rubber may have a high sliding resistance, make noise, or wear out, so there are restrictions on the uses.

For this reason, various methods have been proposed for treating the surface of vulcanized rubber molded products, such as mineral acid treatment and irradiation with high-energy particles or light. Surface-treated products have the disadvantage that the surface of the molded product has a chemical structure and properties different from those of the rubber itself, and as a result, the rubber-like elasticity, which is a characteristic of rubber, is significantly lost.

[Problem that the invention seeks to solve]

As a result of various studies on surface treatment methods for vulcanized rubber molded products that reduce frictional resistance without substantially reducing the inherent properties of rubber, the present inventors have found that:
It has been found that such problems can be effectively solved by using a specific siloxane.

[Means for Solving the Problem] and [Operation] Therefore, the present invention relates to a method for surface treatment of a vulcanized rubber molded article, and the surface treatment involves treating the vulcanized rubber molded article with an alkyl- or aryl-hydrodiene siloxane. This is done by processing.

Vulcanized rubber molded products to be surface treated include natural rubber, butadiene acrylonitrile rubber, butadiene styrene rubber, butyl rubber, hydrin rubber,
Vulcanized molded products of synthetic rubbers such as fluorocarbon rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber, acrylic rubber, and urethane rubber.

Alkyl- or aryl-hydrodiene siloxane used as a surface treatment agent has an alkyl group or an aryl group and a hydrogen atom bonded to the same silicon atom, and has a structure represented by the following general formula. There is.

R ₁ : Methyl group, ethyl group, substituted or unsubstituted phenyl group, etc. R ₂ : Hydrogen atom, methyl group, ethyl group, etc. R ₃ : Methyl group, ethyl group, etc. n: An integer of 2 or more m: 0 or positive Surface treatment with an integer alkyl- or aryl-hydrodiene siloxane can be performed by treating the hydrogen siloxane directly or with aromatic hydrocarbons such as benzene, toluene, xylene, aliphatic hydrocarbons such as ligroin, mineral spirits, or tetrachloride. diluted with a chlorinated hydrocarbon such as carbon, tricrene, or chlorobenzene to a concentration of about 1 to 50% by weight, preferably about 5 to 20% by weight, and brushed;
It is applied to the surface of a vulcanized rubber molded product by any coating method such as spraying or dipping, and then heated and dried at a temperature of about 50 to 200°C for about 10 minutes to 24 hours.

〔Effect of the invention〕

As a result of this surface treatment, a hydrogen siloxane film with a thickness on the order of micrometers is formed on the surface of the vulcanized rubber molded product, which reduces friction and makes the molded product surface non-adhesive by utilizing the inherent elasticity of rubber. be achieved without substantial loss.

This effect is brought about because the hydrogen atoms bonded to silicon in the hydrogen siloxane act as reaction starting points, creating a network structure in the siloxane, which hardens the surface and creates a low-friction, non-adhesive treated layer. This is thought to be due to the formation of Therefore, other siloxanes that do not have such active hydrogen in their molecules do not form a network structure and, on the contrary, increase stickiness.

Furthermore, in the hydrogen siloxane treatment, the rubber molded product is impregnated with hydrogen siloxane up to about 100 μm from the surface, so unlike a simple coating treatment, it will not peel or crack even if it is stretched. .

〔Example〕

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

Example 1 Butadiene acrylonitrile rubber (Japan Synthetic Rubber Products JSR N236H) 100 parts by weight SRF carbon black 50 Zinc oxide 5 Stearic acid 1 Dioctyl adipate 5 Sulfur 1.5 Vulcanization accelerator (dibenzothiazyl disulfide)
1 The above compound was vulcanized at 150°C for 20 minutes, and the resulting vulcanized sheet was vulcanized with hydrogen siloxane (Shin-Etsu Chemical KR280, in the general formula, R ₁ to R ₅ are all methyl groups, and n is 2 3 or more, m is 0 or a positive integer) in a 10% toluene solution.
After soaking for a minute, it was heated and dried at 100°C for 12 hours.

Example 2 Budadiene acrylonitrile rubber (Japan Synthetic Rubber Products JSR N240S) 100 parts by weight FEF carbon black 60 Zinc oxide 5 Stearic acid 1 Dioctyl phthalate 10 Sulfur 1 Vulcanization accelerator (tetramethylthiuram disulfide) 2 Vulcanization accelerator ( N-cyclohexyl-2-benzothiazolylsulfenamide) 2 The above formulation was vulcanized at 165°C for 20 minutes, and the resulting vulcanized sheet was placed in a 15% xylene solution of the hydrodiene siloxane used in Example 1. After being immersed in water for 5 minutes, it was heated and dried at 100°C for 12 hours.

Example 3 Ethylene propylene rubber (Mitsui Petrochemicals Mitsui
EPT1070) 100 parts by weight FEF carbon black 60 Zinc oxide 5 Stearic acid 1 Process oil 10 Sulfur 1.5 Vulcanization accelerator (tetramethylthiuram monosulfide) 1.5 The above mixture was vulcanized at 150°C for 30 minutes to obtain the After immersing the vulcanized sheet in hydrogen siloxane (Shin-Etsu Chemical KF99, in the general formula above, R ₁ to _{R 3} are all methyl groups, n is an integer of 2 or more, and m is 0) for 10 minutes. , heated and dried at 100°C for 15 hours.

Example 4 Chloroprene rubber (electrochemical product DCR S40)
100 parts by weight SRF carbon black 30 Magnesium oxide 4 Zinc oxide 5 Stearic acid 5 2-mercaptoimidazoline 1 The above formulation was vulcanized at 150°C for 20 minutes, and the obtained vulcanized sheet was used as the hydrogen oxide used in Example 3. After immersing in siloxane for 10 minutes, it was heated and dried at 100°C for 12 hours.

Example 5 Acrylic rubber (Noxtite A1095 manufactured by Nippon Mectron) 100 parts by weight FEF carbon black 40 Lead phosphite 5 Stearic acid 2 Sulfuric acid (hexamethylene diamine carbamate)
1 The above compound was vulcanized at 150°C for 30 minutes, and the resulting vulcanized sheet was immersed in the hydrogen siloxane used in Example 3 for 5 minutes, then heated and dried at 100°C for 12 hours.

Example 6 Butadiene styrene rubber (Japanese Synthetic Rubber Products)
SBR1502) 100 parts by weight FEF carbon black 40 Zinc oxide 5 Stearic acid 5 Sulfur 2 Vulcanization accelerator (dibenziazyl disulfide)
3 The above compound was vulcanized at 150°C for 20 minutes, and the resulting vulcanized sheet was vulcanized with hydrogen siloxane (Shin-Etsu Chemical KR285, in the general formula, R ₁ to _{R 3} are all methyl groups, and n is 2 3 or more, m is 0 or a positive integer) in 8% toluene solution.
After soaking for a minute, it was heated and dried at 180°C for 15 minutes.

Example 7 Butadiene acrylonitrile rubber (Japan Synthetic Rubber Products JSR N230S 100 parts by weight HAF carbon black 50 Zinc oxide 5 Stearic acid 2 Sulfur 1 Vulcanization accelerator (tetramethylthiuram monosulfide) 2 The above mixture was heated at 150°C for 20 minutes. The resulting vulcanized sheet was immersed for 3 minutes in the 8% toluene solution of hydrogen siloxane used in Example 6, and then heated and dried at 180° C. for 10 minutes.

Example 8 Butadiene acrylonitrile rubber (Japan Synthetic Rubber Products JSR N241) 100 parts by weight FEF carbon black 40 Zinc oxide 5 Stearic acid 1 Sulfur 1 Vulcanizing agent (tetramethyluram monosulfide)
2 The above compound was vulcanized at 150°C for 20 minutes, and the resulting vulcanized sheet was vulcanized with hydrogen siloxane (in the general formula, R ₁ is a phenyl group and R ₂ to _{R 3} are all methyl groups, 3 in a 20% xylene solution (n is an integer of 2 or more, m is 0 or a positive integer)
After soaking for a minute, it was heated at 150°C for 2 hours and dried.

The surface friction coefficient μ was measured before and after the hydrogen siloxane treatment in each of the above examples. The results obtained are shown in the following table.

Table Examples After treatment pretreatment 1 1.65 0.68 2 1.42 0.70 3 1.50 1.02 4 1.71 0.96 5 1.60 0.92 6 1.40 0.40 7 1.45 0.38 8 1.68 0.82 Also, the vulcanized sheet before and after the hydrogen siloxane treatment in each of the above examples of The presence or absence of cracks on the surface of the 20% elongated products was observed, but no cracks were observed in any case.

Furthermore, when looking at the surface tackiness of these vulcanized sheets, tackiness was observed in all of the sheets before the hydrogen siloxane treatment, but in Examples 3 to 5, the sheets treated by the method of the present invention showed tackiness.
No tackiness was observed at all, except for a slight tackiness observed in the sample.

Claims (1)

[Claims] 1. A vulcanized rubber molded product according to the general formula (Here, R ₁ is a lower alkyl group or an aryl group, R ₂ is a hydrogen atom or a lower alkyl group, R ₃ is a lower alkyl group, n is an integer of 2 or more, and m is 0 or a positive integer)
A method for surface treatment of vulcanized rubber molded products, characterized by treatment with hydrogen siloxane.