Adhesive laminated packaging materials

Abstract

A three-ply, flexible, laminated, heat-sealable packaging material which is resistant to flex cracking and pinhole development is made by bonding an inner film of a heat-sealable polymeric material to one surface of a core film of biaxially oriented polypropylene coated on both sides with Saran and by bonding an outer film of biaxially oriented polypropylene to the other surface of the core film with an adhesive composition including bond formers consisting essentially of about 70 to about 90 weight % of an ethylene-vinyl acetate copolymer which contains about 20 to about 40 weight % vinyl acetate, about 10 to about 30 weight % of a tackifying resin, and 0 to about 5 weight % of a plasticizer. A coating of the adhesive composition is applied to the inner surface of the outer film as an organic solvent solution and the coating dried to provide a residual layer of the bond formers which provides the bond between the core film and the outer film. A two-ply, heat-sealable packaging material is made by omitting the outer film and bonding a film similar to the above core film to an inner film of a heat-sealable polymeric material with the above adhesive composition.

Dependencies are inferred from the claim text.