Process for the production of a transparent polyolefin multilayer film

A process for the production of a transparent, printable, biaxially oriented polyolefin multilayer film which can be sealed on both sides, comprising a base layer B and different top layers A and C located on both sides thereof corresponding to a layer build-up of ABC;

• wherein
• a) the base layer B comprises a peroxidically degraded polypropylene polymer having a degradation factor in the range from about 3 to about 10, and
• b) the top layer A comprises a polymer mixture of two or more of the following polymers:
• a copolymer of
• ethylene and propylene or
• ethylene and butylene or
• propylene and butylene or
• ethylene and another .alpha.-olefin having 5 to 10 carbon atoms or
• propylene and another .alpha.-olefin having 5 to 10 carbon atoms or
• a terpolymer of
• ethylene and propylene and butylene or
• ethylene and propylene and another .alpha.-olefin having 5 to 10 carbon atoms;
• and
• a polydiorganosiloxane and silicon dioxide, and
• c) the top layer C comprises
• a copolymer of
• ethylene and propylene or
• ethylene and butylene or
• propylene and butylene or
• ethylene and another .alpha.-olefin having 5 to 10 carbon atoms or
• propylene and another .alpha.-olefin having 5 to 10 carbon atoms or
• a terpolymer of
• ethylene and propylene and butylene or
• ethylene and propylene and another .alpha.-olefin having 5 to 10 carbon atoms, and a non-cohesive covering of polydialkylsiloxane on its outer surface, comprising:
• (i) coextruding through a flat die melts corresponding to the individual layers of the film,
• (ii) taking off and cooling to consolidate the resulting film, via a take-off roll,
• (iii) biaxially stretching the consolidated film,
• (iv) thermofixing the biaxially stretched film, and
• (v) covering top layer C with a non-cohesive layer of polydialkylsiloxane.