SHRINKABLE DRAWN TUBULAR FILM BY MULTILAYER COEXTRUSION

摘要

PURPOSE: To improve the opacity of a color film by adding a filler incompatible with a propylene base polymeric matrix and forming voids imparting opacity at a time of biaxial stretching to one layer consisting of polyamide and a propylene (co)polymer subjected to multilayer extrusion. CONSTITUTION: In a co-extruded biaxially stretched tubular film consisting of a polyamide layer and at least other one separate propylene (co)polymer layer, the propylene (co)polymer layer has voids generating opacity. The voids of a polypropylene layer are generated as a result of the addition of particles of an inorg. filler such as calcium carbonate or titanium dioxide or particles of an org. filler such as polyethylene terephthalate or polycarbonate to polyolefin and the simultaneous biaxial stretching of the polypropylene layer under a stretching condition typical to polyamide. By this constitution, the opacity of a color film can be improved.