Hydrogenated nitrile rubber composition

Abstract

A hydrogenated nitrite rubber composition capable of providing a cross-linked product having a 20% modulus of 10 MPa or more and a thermal conductivity of 0.4 W / m.K or more at 25 DEG C., which comprises 100 parts by weight of hydrogenated nitrile rubber having a bound acrylonitrile content of 40% or more, a polymer Mooney viscosity ML1+4 (100 DEG C.) of 75 or less (median) according to JIS K-6395 and iodine value of 23 or less (median), and not less than 110 parts by weight in sum total as a filler consisting of carbon black and other gas shielding fillers, can be effectively used as a molding material for sliding application or for a static sealing member for highly permeable gas, because of distinguished carbon dioxide gas shieldability, heat resistance, wear characteristics, etc.

Description

technical field [0001] This invention relates to hydrogenated nitrile rubber compositions. More specifically, it relates to a hydrogenated nitrile rubber composition capable of providing a cross-linked molded article having excellent properties such as gas barrier properties, heat resistance, and abrasion resistance. Background technique [0002] Currently, Flon R-134a (1,1,1,2-tetrafluoroethane), which is called a new refrigerant, is the mainstream refrigerant used in refrigerators, etc. As a substitute for this refrigerant, hydrocarbon-based gas or carbon dioxide gas has attracted attention. Among them, since the risk of explosion and combustion of hydrocarbon-based gases is very high, it can be said that the use of carbon dioxide gas is advancing as a next-generation refrigerant worldwide. [0003] However, carbon dioxide gas has a higher pressure than flon, and has high permeability and solubility to commonly used polymer materials, so foaming (foaming) is easy to occu...

AI Technical Summary

Problems solved by technology

[0003] However, carbon dioxide gas has a higher pressure than flon, and has high permeability and solubility to commonly used polymer materials, so foaming (foaming) is easy to occur. Even if no foaming occurs, the polymer material itself is permeable. Difficult to maintain pressure and keep a seal over carbon dioxide

[0004] Even rubber materials generally have high carbon dioxide permeability, especially at 1MPa or above, so the carbon dioxide gas cannot be sufficiently sealed.

Moreover, carbon dioxide gas is easily dissolved in the polymer, so the expansion is large, so that the parts of rubber materials cannot be used in the device using carbon dioxide gas, which is the actual situation

[0005] In order to solve these problems, as a material for sealing carbon dioxide, it is proposed to add CTAB to butyl rubber with a specific surface area of ​​about 30-100m 2 Carbon black butyl rubber composition (JP-A-2000-053718) or chlorinated polyethylene with a chlorine content of 25 to 47% by weight or a blend of it and a vinyl chloride resin for carbon dioxide Molding materials (WO 01 / 09237) are used as molding materials for O-rings, lip seals, etc. Although these materials have sufficient carbon dioxide shielding properties, they are not sufficient in terms of heat resistance or wear characteristics

[0006] On the other hand, in order to improve heat resistance and wear characteristics, hydrogenated NBR highly filled with fillers has been proposed (JP-A-2002-080639, JP-A-2002-146342), but the shielding property of carbon dioxide is not as good as that of butyl rubber or chlorinated polyethylene