Biaxially stretched shrinkable single- or multilayer tubular thermoplastic film for use as tubular packaging sheath for paste-like material, has inert inorganic filler having an average diameter less than 20 microns and porous structure

摘要

A biaxially stretched shrinkable single- or multilayer tubular thermoplastic film is characterized in that at least one film layer comprises 20-60 wt.% of an inert inorganic filler having an average diameter less than 20 microns and a porous structure. A biaxially stretched shrinkable single- or multilayer tubular thermoplastic film (I) for use as tubular packaging sheath for paste-like material, preferably synthetic sausage skin is characterized in that to increase permeability to water vapor and gas with retention of water impermeability, at least one film layer comprises 20-60 wt.% of an inert inorganic filler (I) having an average diameter of less than 20 microns and a porous structure. An Independent claim is also included for a process for the production of the film by melting a granulate or mixture of a thermoplastic and 20-60 wt.% of the filler (II) in an extruder and extruding the melt through a ring nozzle to form a primary tube that is calibrated and cooled followed by heating and applying a pressure difference between the inside of the primary tube and the environment and applying a longitudinal force to apply a biaxial stretch followed by relaxing, thermofixing and optionally cold or hot post orientation.