The present invention relates to a process for preparing a vulcanisable elastomeric compound for tyres, characterised by the use of a particular vulcanisation-activating filler and by the methods of adding additives, in particular the compatibilising agent (silane), which occurs only after completion of the reaction between the activating filler comprising zinc and the fatty acid (stearic acid). The present process, advantageous in itself due to the possible reduction of the times and of the energy required for vulcanisation, allows preparing compounds which, with the same performances compared to the traditional ones, can have a reduced zinc content, and consequently a lower release thereof from tyres during use at an environmental level.

Provided is a dip molding composition which contains at least: a carboxyl group-containing nitrile rubber elastomer; an epoxy crosslinking agent containing an epoxy compound that contains three or more glycidyl ether groups in one molecule and has a basic skeleton containing an alicyclic, aliphatic or aromatic hydrocarbon; and a pH modifier. In this dip molding composition, the elastomer contains 50% by weight or more, 78% by weight or less of a conjugated diene monomer-derived structural unit, 20% by weight or more, 30% by weight or less of an ethylenically unsaturated nitrile monomer-derived structural unit, and 3.5% by weight or more, 6% by weight or less of an ethylenically unsaturated carboxylic acid monomer-derived structural unit; the elastomer has an MEK-insoluble content of 60% by weight or more, 80% by weight or less; and the epoxy crosslinking agent has an MIBK/water distribution ratio of 50% or higher.

Provided is a dip molding composition which contains at least: a carboxyl group-containing nitrile rubber elastomer; an epoxy crosslinking agent containing an epoxy compound that contains three or more glycidyl ether groups in one molecule and has a basic skeleton containing an alicyclic, aliphatic or aromatic hydrocarbon; and a pH modifier. In this dip molding composition, the elastomer contains 50% by weight or more, 78% by weight or less of a conjugated diene monomer-derived structural unit, 20% by weight or more, 30% by weight or less of an ethylenically unsaturated nitrile monomer-derived structural unit, and 3.5% by weight or more, 6% by weight or less of an ethylenically unsaturated carboxylic acid monomer-derived structural unit; the elastomer has an MEK-insoluble content of 60% by weight or more, 80% by weight or less; and the epoxy crosslinking agent has an MIBK/water distribution ratio of 50% or higher.

A gasket material, in which a crosslinked rubber layer compounding 30 to 200 parts by weight of titanium oxide based on 100 parts by weight of NBR or hydrogenated NBR is formed on a metal plate, improves blister resistance, and thus exhibits an excellent effect of preventing rubber peeling of the gasket in the engine and leading to an improvement of engine malfunction. Further, the use of NBR or hydrogenated NBR results in an advantage of low cost relative to that of fluororubber. Therefore, the gasket material of the present invention is effectively used as a cylinder head gasket.

A gasket material, in which a crosslinked rubber layer compounding 30 to 200 parts by weight of titanium oxide based on 100 parts by weight of NBR or hydrogenated NBR is formed on a metal plate, improves blister resistance, and thus exhibits an excellent effect of preventing rubber peeling of the gasket in the engine and leading to an improvement of engine malfunction. Further, the use of NBR or hydrogenated NBR results in an advantage of low cost relative to that of fluororubber. Therefore, the gasket material of the present invention is effectively used as a cylinder head gasket.

Provided is a dip molding emulsion including, at least: an elastomer that contains a (meth)acrylonitrile-derived structural unit, an unsaturated carboxylic acid-derived structural unit, and a butadiene-derived structural unit in a polymer main chain; an epoxy crosslinking agent; water; and a pH modifier, in which dip molding composition the elastomer contains the (meth)acrylonitrile-derived structural unit in an amount of 20% by weight to 40% by weight, the unsaturated carboxylic acid-derived structural unit in an amount of 1% by weight to 10% by weight, and the butadiene-derived structural unit in an amount of 50% by weight to 75% by weight, and the epoxy crosslinking agent includes an epoxy crosslinking agent containing an epoxy compound having three or more epoxy groups in one molecule and has a dissolution rate in water of 10% to 70% as determined by a specific measurement method.

Provided is a dip molding emulsion including, at least: an elastomer that contains a (meth)acrylonitrile-derived structural unit, an unsaturated carboxylic acid-derived structural unit, and a butadiene-derived structural unit in a polymer main chain; an epoxy crosslinking agent; water; and a pH modifier, in which dip molding composition the elastomer contains the (meth)acrylonitrile-derived structural unit in an amount of 20% by weight to 40% by weight, the unsaturated carboxylic acid-derived structural unit in an amount of 1% by weight to 10% by weight, and the butadiene-derived structural unit in an amount of 50% by weight to 75% by weight, and the epoxy crosslinking agent includes an epoxy crosslinking agent containing an epoxy compound having three or more epoxy groups in one molecule and has a dissolution rate in water of 10% to 70% as determined by a specific measurement method.

Provided is an electrophotographic electroconductive member including an electroconductive support and an electroconductive layer on the support, an electroconductive member is used, in which an electroconductive layer has a matrix comprising a first rubber, and domains dispersed in the matrix, the domains each comprising a second rubber and an electronic electroconductive agent, and for impedance measured by applying an AC voltage with an amplitude of 1 V to the electroconductive layer while varying frequencies between 1.0×10.sup.−2 Hz to 1.0×10.sup.7 Hz under a specific environment, when a double logarithmic plot with a frequency on an abscissa and an impedance on an ordinate is obtained, a slope on a high frequency side is −0.8 or more and —0.3 or less, and the impedance a low frequency side is from 1.0×10.sup.3 to 1.0×10.sup.7Ω.

Disclosed is a gas seal member for high-pressure hydrogen device with sufficiently reduced occurrence of both swelling destruction and blister destruction. The gas seal member is formed of a cross-linked product of an elastomer composition which comprises an elastomer and fibrous carbon nanostructures, wherein a hydrogen diffusion coefficient D1 of a cross-linked product of an elastomer component including the elastomer and a hydrogen diffusion coefficient D2 of the cross-linked product of the elastomer composition satisfy the relationship 0.7<D2/D1<1.0.

Disclosed is a gas seal member for high-pressure hydrogen device with sufficiently reduced occurrence of both swelling destruction and blister destruction. The gas seal member is formed of a cross-linked product of an elastomer composition which comprises an elastomer and fibrous carbon nanostructures, wherein a hydrogen diffusion coefficient D1 of a cross-linked product of an elastomer component including the elastomer and a hydrogen diffusion coefficient D2 of the cross-linked product of the elastomer composition satisfy the relationship 0.7<D2/D1<1.0.