Extrusion coating process for making high transparency protective and decorative films

Abstract

A process for making a protective and decorative surfacing film comprises extrusion coating a solventless polymeric material from an extruder die to form an optically clear first layer on a polyester carrier sheet traveling past the extruder die opening. The extrusion coated first layer is immediately cooled on the carrier sheet to harden it, followed by applying a pigmented second layer to the first layer. The composite paint coat is transferred to a reinforcing backing sheet, after which the carrier sheet is separated from the paint coat to expose the outer surface of the first layer as a high gloss surface with a high distinctness-of-image, providing a transparent protective outer coat for the pigmented second layer. The pigmented second layer can be solvent cast and dried or extruded and hardened as a separate coating on the first layer. The composite paint coat can be bonded to a coextruded size coat and semi-rigid plastic substrate panel to form a thermoformable laminate. Techniques are disclosed for producing extruded clear films of exceedingly high optical clarity using a closed air flow transport and HEPA filtration system that removes airborne particles from the resin handling and extrusion process, thereby preventing micron-sized contaminants naturally present from many sources from entering the process and degrading ultimate film quality.