Transparent, biaxially orientated polyolefinic film with improved bonding properties

Method for printing a co-extruded polyolefin film, said polyolefin film comprising a base layer and a first outer layer, both base and first outer layers having first and second surfaces, said first surface of said first outer layer disposed on said first surface of said base layer, wherein said base layer is built up from polyolefinic polymers and said first outer layer comprises a single polymer consisting entirely of a maleic anhydride-modified polyolefin, said method consisting essentially of

• applying a first surface treatment to said second surface of said first outer layer by plasma, corona or flame-treating said second surface of said first outer layer during film manufacturing;
• applying a second surface treatment to said second surface of said first outer layer by applying a plasma, corona or flame treatment to said second surface of said first outer layer subsequent to said first surface treatment;
• and
• printing the second surface of said first outer layer subsequent to said second surface treatment,
• wherein (i) the surface tension imparted by the first surface treatment is the same as the surface tension imparted by the second surface treatment,
• (ii) printing adhesion is enhanced by said first and second surface treatments alone,
• (iii) said film is formed using a longitudinal stretching ratio ranging from 4 to 8 and a transverse stretching ratio ranging from 5 to 10 and
• (iv) the surface tension imparted by the first and second surface treatments ranges from 42 to 50 mN/m.