To enable attainment of fire retardance without using a fire retardant additive and without lowering an etching flow index during sheet processing, by laminating a metal thin film on both surfaces of a sheet molded out of a polypropylene composition constituted of a specific olefin copolymer of a specified amount and specific polypropylene of a specified amount.
A composite sheet having fire retardance is prepared by laminating a metal thin film on both surfaces of a sheet molded out of a specific polypropylene composition. The specific polypropylene composition is constituted of polypropylene of 100 pts.wt. of which the intrinsic viscosity measured in tetralin at 135°C is 0.2-10 dl/g and which is constituted of a propylene-olefin copolymer containing an olefin (co)polymer of 0.01-5 pts.wt. of which the intrinsic viscosity measured in the tetralin at 135°C is 15-100 dl/g and a propylene monopolymer or a propylene polymerization unit of 50 wt.% or more. For a method of joining the polypropylene composition and metal sheets, an ordinary adhesive or adhesive polyolefin resin is used.
NAKAGAWA YASUHIKO
YOKOTA JUNICHIRO
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