JP2775743B

PURPOSE:To greatly improve the boundary adhesiveness between a core material layer and clad material layer by using an elastomer material having rubberlike elasticity for said materials and co-extruding these materials, then bringing the extruded materials into crosslinking reaction. CONSTITUTION:A crosslinkable group-contg. elastomer having the glass transition temp. below room temp. or a mixture composed of said elastomer and a crosslinking agent is used as the material of the core material and the clad material. After the core material and the clad material are co-extruded, the co-extrudate is co-crosslinked by heating or photoirradiation to impart a chemical bond to the boundary between the core material layer and the clad material layer. The boundary adhesiveness is thereby greatly improved and since the materials having less difference in modulus of elasticity are usable for the respective materials, the boundary exfoliation between the two layers as against a large deformation is effectively prevented.