Method and Plant for Etching a Fluoropolymer Substrate

A (semi-)continuous etching plant (1) for increasing the surface adhesion of a fluoropolymer substrate (10) comprising:

• feeding means (22) of the fluoropolymer substrate (10) in the form of a continuous ribbon or film along a feeding direction (X), said substrate defining a primary surface (12);
• one or more etching tanks (2) containing an adhesion-promoting solution comprising a complex of an alkali metal in naphthalene for the chemical etching of at least a part of the primary surface (12);
• a removal bath (4) of the adhesion-promoting solution from the part of the primary surface (12) wetted by said solution, said removal bath containing a washing solution (42) comprising aqueous acetic acid or aqueous formic acid;
• inverse osmosis stations (6, 8) working at increasing pressure, configured to selectively separate a concentrated solution (24) of acetic acid or of formic acid from the washing solution (42);
• means for re-introducing (26) at least a portion of the concentrated solution (24) of acetic acid or of formic acid in the washing solution (42) to create a recirculation.