Production of biologically degradable films

Claim 1

Method of preparing a biologically degradable film composed of non-biologically degradable synthetic polymer and a biologically degradable polymer, which comprises subjecting particles of said biologically degradable polymer (biopolymer) in aqueous suspension to enzymes that split said biologically degradable polymer to small molecules which are released from the surface of the biopolymer particles and continuing the subjecting of said biologically degradable polymer to said enzymes until particles of predetermined small size are obtained, emulsifying the thus formed biopolymer particles of predetermined small size with a vegetable oil to coat the thus formed particles with the vegetable oil, thus isolating the enzyme from the water of the aqueous suspension and interrupting the degradation of the biopolymers by the enzymes, the enzymes remaining on the biopolymer particles, separating the thus vegetable oil-coated particles from the suspension, drying and then pulverizing the same, and mixing the thus obtained pulverized biopolymer particles with said synthetic polymer and forming a film therefrom in a film extruder, wherein the biopolymer degradation continues only after oxidation of the oil film which permits contact of the enzymes with moisture.