COMPOSITE GASKET MATERIAL AND PRODUCTION OF THE SAME

PURPOSE:To obtain the title material used for preparing a gasket having excellent sealing properties at low cost, by forming foam-free rubber layers on both sides of a metallic substrate sheet and thereafter forming foam rubber layers on the surface thereof. CONSTITUTION:A non-foamable rubber soln. contg. a rubber material, such as a natural rubber, a synthetic rubber and a thermoplastic elastomer, and optionally a rubber compounding agent, such as a vulcanizing agent (promoter), a retardant and a reinforcing agent, is applied to both sides of a metallic substrate sheet 2 (e.g., steel plate) optionally surface treated. Drying and vulcanization are performed to form foam-free rubber layers 4 having a thickness of 2mum or more. Subsequently, a foamable rubber soln. comprising a rubber and a thermoplastic rubber, a heat-decomposable foaming agent (e.g., dinitropentamethylenetetramine) and optionally a foaming auxiliary, a rubber compounding agent and/or a rubber solvent is applied to the surfaces of foam- free rubber layers 4. After drying, the whole is heated so as to conduct foaming and vulcanization, thereby forming foam rubber layers 3 having a density of 10-800kg/m and a thickness of 0.05-2mm. Thus, a composite gasket material 1 is prepd.