Patent ID: 7553389

Claim:
A process for coating a metal sheet, comprising: A) in-line transporting a metal sheet having opposed substantially planar first and second surfaces extending between opposite lateral edges, the first surface having an inorganic-metallic protective coating extending between the lateral edges; B) activating a first metallic surface of the inorganic-metallic protective coating to enhance reception and retention of a multi-layer polymeric coating on the activated first metallic surface; C) melt co-extruding the multi-layer polymeric coating on the activated first metallic surface and beyond the opposite lateral edges to establish overhang portions, the multi-layer polymeric coating comprising (i) a polymeric tie layer contacting the activated first metallic surface in direct surface-to-surface contact, the tie layer comprising anhydride-modifled polyethylene, while presenting the activated first surface at ambient temperature; and (ii) a polymeric finish layer in overlaying and coextensive relationship with the tie layer, the finish layer comprising a member selected from polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and a combination of PBT and PET; D) solidifying the extruded multi-layer polymer coating, including the overhang portions; and E) subjecting the extruded multi-layer polymeric coating to finish-treatment, comprising heating the extruded multi-layer polymeric coating at least to a melt temperature thereof, then cooling the multi-layer polymeric coating through a glass-transition temperature thereof at a sufficiently rapid rate to establish amorphous non-directional characteristics in the multi-layer polymeric coating.