the invention relates to a method of producing a film comprising at least one layer of a polymer selected from among thermoplastic fluoro - polymer and polymers . the inventive method consists in using extrusion blow moulding to coextrude the following : a ) at least one layer of a thermoplastic fluoro - polymer and at least one layer of polymer ; or b ) at least one layer of a thermoplastic fluoro - polymer containing charges and optionally at least one other fluoro - polymer layer ; or c ) at least one layer of polymer , the layers extruded in a ), b ) or c ) adhering to one another ; d ) a layer of another thermoplastic polymer such that it forms a layer which is adjacent to the assembly of layers extruded in a ), b ) or c ); e ) optionally another layer of which is adjacent to the assembly of layers extruded in a ), b ) or c ) on the side opposite that of the layer extruded in d ). according to the invention , the thermoplastic polymer is incompatible with the fluoro - polymer and polymer and has adequate extrudate behaviour to support the layers of fluoro - polymer and / or polymer . once the coextrudate has been cooled , by separating the layer of , at least the film is recovered , said film comprising at least one layer of a polymer selected from among thermoplastic fluoro - polymers and polymers .