PRODUCTION OF CHIP FOIL MADE OF PLASTIC

摘要

PURPOSE:To obtain a chip foil excellent in firmness, folding endurance and tear strength by a method wherein a biaxially stretched two-layer tubular film consisting of an inner layer of polystyrene (PS) and an outer layer of high-density polyethylene (PE) is folded flat, then the inner PS layers are press adhered to each other and the resultant material is cut to predetermined length. CONSTITUTION:By a two-layer inflation molding method, the PS for forming the inner layer and the high-density PE for forming the outer layer are coextruded, for example, by an in-die contact coextrusion method at a temperature of 180-220 deg.C and is inflated at a blow-up ratio of 3.0-6.0 to obtan the biaxially stretched two-layer tubular film having a total film thicknes of, for example, 40-150mu and consisting of the inner PS layer of a thickness of 70-90% of the total film thickness and the outer high-density PE layer of a thickness of 30-10% of the total film thickness. Then, the tubular film is folded flat, the inner layers are press adhered to ech other by embossing and the resultant material is cut to the predetermined length to obtan the chip foils. In this case, when projecting streaks and recessed grooves are formed alternately in the circumferential direction, the rigidity of the chip foil can be further enhanced. The PS provides the firmness for the chip foil, while the high-density PE provides tensile strength, tear strength, chemical resistance, oil resistance and the like.