PURPOSE: To prevent the wall thickness of a container from remarkably increasing, by extruding a thermoplastic resin foamed sheet, then immediately packing it in a film having an air permeability of up to 0.2g/m2.24hr.atm. at 20°C when the thickness of the film is 0.01mm.
CONSTITUTION: After a thermoplastic resin such as polystyrene, polyethylenes, etc. is melted and kneaded together with a foaming agent such as trichlorofluoromethane, etc. under heating and pressure, the mixture is extruded at normal temperatures under normal pressures into a thermoplastic resin foamed sheet. Then immediately thereafter, the foamed sheet is wound into a roll and is sealed and packed in a film having an air permeability of up to 0.2g/m2.24hr. atm. at 20°C when the thickness of the film is 0.01mm with the film in firm contact with the roll, so that air would not be included in the package. According to this method, even if there is difference in passed period from the production of the foamed sheet to the forming of a container therefrom, the scatter of the wall thickness of the obtained containers can be reduced between the lots.
HASEGAWA TAKESHI
OGURA CHIYUUKIYUU
KUROSAWA EIJI
NIHON ZANPATSUKU KK