Biaxially oriented polyolefin multi-layer film

A process for the preparation of a multilayer polyolefin film comprising a polypropylene base layer;

• a first polyolefin sealing layer positioned on one side of said base layer, and containing from about 0.5% to about 3% by weight of incorporated polydialkylsiloxane;
• a second polyolefin sealing layer positioned on the other side of said base layer, said second sealing layer being subjected to corona treatment and being substantially free of polydialkylsiloxane at the time of said corona treatment, and said second polyolefin sealing layer having a coating of polydialkylsiloxane on its outer surface, applied subsequent to said corona treatment;
• the relative polydialkylsiloxane occupancy of said second sealing layer being not more than about 15 as determined by means of ESCA spectroscopy, comprising the steps of:
• producing said multilayer film by coextruding a plurality of melts corresponding to said layers of said multilayer film;
• biaxially orienting the film;
• subjecting said second sealing layer to corona treatment;
• and
• arranging the film in a manner such that said first and second sealing layers contact each other sufficient to produce said coating of polydialkylsiloxane.