Abstract: A push button switch covering member of a silicone rubber is imparted with excellent resistance against stain deposition and abrasive wearing by providing a protective overcoating layer of a urethane resin-based coating composition capable of being cured by forming urethane linkages between isocyanate groups of a polyisocyanate compound and hydroxy groups of a polyhydroxy compound. The coating procedure with the coating composition on the surface of a silicone rubber-made covering member is preceded by a plasma treatment so as to activate the surface resulting in an increased adhesive bonding strength between the silicone rubber body and the coating layer. The improvement is more remarkable when the plasma-activated surface is subjected to a priming treatment with a silane coupling agent and coating with the coating composition is undertaken as soon as possible or within 60 minutes after completion of the plasma treatment.

Abstract: Proposed is a cured silicone rubber article such as a push button switch covering member having a protective coating layer of a urethane resin-based coating composition having excellent wear resistance against rubbing and capable of giving a dry and rigid touch feeling to the finger tip of the operator of the key tops. The coated silicone rubber article is obtained by subjecting a cured base body of a silicone rubber, prior to the coating with a urethane resin-based coating composition, first to a low temperature plasma treatment and then to a coating treatment with a specific primer composition which is a mixture of an epoxy group-containing organosilane compound and an amino group-containing organosilane compound in a molar mixing ratio in the range from 1:2 to 1:5.

Abstract: A push button switch covering member of a silicone rubber is imparted with excellent resistance against stain deposition and abrasive wearing by providing a protective overcoating layer of a urethane resin-based coating composition capable of being cured by forming urethane linkages between isocyanate groups of a polyisocyanate compound and hydroxy groups of a polyhydroxy compound. The coating procedure with the coating composition on the surface of a silicone rubber-made covering member is preceded by a plasma treatment so as to activate the surface resulting in an increased adhesive bonding strength between the silicone rubber body and the coating layer. The improvement is more remarkable when the plasma-activated surface is subjected to a priming treatment with a silane coupling agent and coating with the coating composition is undertaken as soon as possible or within 60 minutes after completion of the plasma treatment.

Abstract: A process for preparing calcium silicate articles having a bulk density of 0.3 to 0.9 g/cm.sup.3 including the steps of mixing a major portion of calcium silicate and minor portions of anhydrous calcium aluminosilicate or its analogue, a reinforcing fiber and a polymer binder in water to give an aqueous slurry, molding the slurry into a desired for, and drying the molded slurry at 100.degree.-180.degree. C.