FILM/SUBSTRATE COMPOSITE MATERIAL

摘要

PROBLEM TO BE SOLVED: To prevent the generation of blisters in the boundary surface of a film and polystyrene, in a composite material consisting of a support comprising polystyrene and the film bonded to the support, by providing a bonding layer of a styrene/butadiene copolymer to the film and adding butadiene to the bonding layer in specific wt.% or more. SOLUTION: A thermoformable sheet 20 for molding a tray is constituted of a multilayered film 22, a foamed polystyrene sheet 30 and a film. The film 32 comprises a single-layered film pref. comprising rubber modified polystyrene and an outer layer is formed by this film to apply strength and crack resistance to a tray. Further, a core layer 26 imparting gaseous oxygen barrier properties and the bonding layer 28 bonded to the polystyrene sheet 30 at the film/foam boundary surface 34 are provided to the sheet 20. The pref. compsn. of the bonding layer 28 contains a copolymer of styrene and at least one comonomer selected from butadiene and acrylonitrile and the bonding layer contains butadiene at least in an amt. of 25 wt.%.