Heat-shrinkable food packaging films - comprising laminates of PVDC and oriented polyethylene, for sterilisable packs which exclude oxygen

摘要

Heat-shrinkable bags or sachets for packaging foodstuffs are made by folding and welding laminated films comprising two layers of oriented polyethylene (I) with an intermediate layer of PVdc (II) to act as a barrier layer to oxygen. Specifically, (I) is a homopolymer or is a copolymer contg. =5% wt. vinyl acetate or =3% wt. propylene, and is oriented and irradiated prior to being coated with (II), pref. by deposition from soln. Opt. the internal surfaces of the layers of (I) are coated with an interfacial adhesive prior to being coated with/laid up on (II). The ratio of the thickness of (I) and (II) is =7:1 pref. 8:1, opt up to 25:1, typically with thicknesses of 19-35 mu m for (I) and up to 6 mu m for (II). Suitable for enclosing, packages to be pasteurised or sterilised using temps. in the range 80-120 degrees C.