Thermoformable conductive laminate and process

Abstract

A process for making a thermoformable conductive plastic laminate for use in making plastic parts adapted for electrostatic spray painting of a uniform high quality paint finish includes forming a matte release coated casting sheet, casting an electrically conductive polymer in thin film form on the casting sheet, drying to form a conductive primer coat, and transfer-laminating the conductive coating to a thin, thermoformable plastic face sheet. The matte release coat has a fine particulate filler that transfers a micro-toughened matte surface to the conductive primer coat. The conductive primer includes a polyester resin containing a fine particulate conductive material such as carbon black and, preferably, an anti-blocking agent such as fumed silica. The primer coated face sheet can be thermoformed and bonded to a underlying plastic substrate panel. The conductive primer has sufficient elongation and maintains uniform electrical surface conductivity and film thickness throughout the transfer-laminating, thermoforming and substrate panel-cladding process. The uniform surface resistivity of the conductive primer film is sufficient to permit electrostatic spray painting of the finished contoured panel and in one embodiment produces a Class 'A' quality exterior automotive paint finish on the resulting panel.