MANUFACTURE OF COMPOSITE FORMED BODY SHEET OF POLYOLEFIN

PURPOSE:To manufacture a composite foamed body sheet of strong surface and good thermal processing properties by extruding a sheet of mixture of polyolefin, a crosslinking agent and a foaming agent, laminating a polyolefin sheet not containing the foaming agent or slightly containing the same over said extruded sheet and bonding thereon, heating said composite body sheet, crosslinking and foaming. CONSTITUTION:Polyolefin is a polymer or a copolymer of ethylene, propylene or butene. A crosslinking agent which is decomposed by heating crosslinks polyolefin, and is an organic peroxide such as dicumyl peroxide, azide and a silane compound having a vinyl radical. The foaming agent is decomposed to generate gas, and is PP'-oxybisbenzenesulfonyl hydrazide, azodicarbonamide or the like, and its decomposition temperature is higher than that of the crosslinking agent. Therefore, when the foaming agent is heated, first the crosslinking is started, and then the foaming agent is decomposed and expanded.