Predominantly biodegradable release film

A multi-layer, more than 50% by weight biodegradable removable protective film or liner film consisting of

• (a) one backing layer based on at least one biodegradable polymer selected from the group consisting of lactic acid homopolymers, lactic acid copolymers, polylactides, polyhydroxyalkanoates, thermoplastic starch, polyester, at least partly hydrolyzed polyvinyl acetates, ethylene-vinyl alcohol copolymers, copolymers of at least two monomers of the stated polymers, and mixtures of at least two of the stated polymers and
• (b) one release layer based on at least one cured polysiloxane which curing is based at least partly on a reaction with at least one crosslinking monomeric or oligomeric additive,
• said additive also causing the adhesion between the backing layer (a) and the release layer (b), with the consequence that no separate adhesion promoting layer is present between the backing layer (a) and the release layer (b), whereby
• the additive used contains no siloxane groups,
• has at least two functional groups of which at least one is a functional group containing at least one carbon double bond, and
• at least one functional group not consumed by the curing of the polysiloxane causing said adhesion promotion between the backing layer (a) and the release layer (b), which is selected from the group consisting of hydroxyl groups, carboxyl groups, and acid anhydride groups,
• (c) and having at least one further substrate layer (c) based on at least one biodegradable polymer selected from the group consisting of cellulose, cellulose derivatives, paper, and thermoplastic starch.