Multi-layer tubular film esp. for sausage casings - which hold the meat, after cooking, in a tight unwrinkled package

摘要

A tubular packing film, esp. for sausages and meats which have to be cooked after packing, comprises >=2 layers of different thermoplastic materials, the inner layer in contact with the meat being practically impermeable to water and resistant to dilute acids, whilst the outer layer has a high water-absorption capability accentuated by treatment with a dilute acid. During storage in refrigerated rooms after cooking, the outer layer is able to dry out and shrink, enclosing the pack in a tight, smooth unwrinkled case. The casing is improved by using an inner layer composed of PVC or polyester, pref. polybutyleneterephthalate, whilst the outer layer is an elastic material such as polyester-elastomers, polyphenylene oxide or polysulphones. The relative thickness of the layers ranges from as 1:1-6 or 30-70 mu. The materials are cheaper and the shrinking of the outer layer takes place without drying out; the elasticity of the material being unaffected by heat.