PURPOSE: To obtain a case that has no distortion and can be printed by a multicolor offset printing system to be enhanced in outward appearance by a method wherein composite synthetic paper is provided with a biaxially oriented film having fine pores as a base layer and a uniaxially oriented film containing a specific weight percentage of inorganic fine powder as a paper layer, and a substrate made of an extruded resin foamed sheet of a specific wall thickness and a specific expansion ratio is bonded to the surface of the composite synthetic paper opposite to the paper layer.
CONSTITUTION: On at least one surface of a substrate A containing an extruded resin foamed sheet having an expansion ratio of 1.05-10 and a wall thickness of 50μm or more, composite synthetic paper B of a wall thickness 30-300μm provided with a biaxially oriented thermoplastic film having fine pores as a base layer B1 and a uniaxially oriented film of a thermoplastic resin containing 8-65wt.% inorganic fine powder as a paper layer B2 is integrally bonded so that the paper layer B2 forms a top surface. A case-forming blank 3 formed out of an obtained laminated sheet having a wall thickness of 100-1100μm is folded. Overlap width parts 3b of the blank 3 and parts 3c to be overlapped with the overlap width parts are thermally fused to each other by high-frequency heating.
CHIBA NORIYOSHI
TAKEYAMA TADAO
