A process has been adapted for applying weatherable, optically-clear, abrasion-resistant coatings for thermoplastics used on automotive exteriors. The process, called “flowcoating”, offers significant benefits in transfer efficiency, quality, throughput and cost over traditional coating application methods. Flowcoating consists of controlled gravity flow of a coating over the substrate. Excess coating is collected, filtered, combined with fresh coating and make-up solvent, then re-used. This results in less solid waste and lower material usage. Currently used to apply thermally-cured silicone hardcoats to polycarbonate molded parts, flowcoating results in a scratch-resistant, long-lasting finish, with higher gloss and (distinctness of image) DOI than with conventional spray techniques.
While the process is surprisingly simple, flexible and easy to maintain, there are considerations in part design, coating and equipment selection which must be addressed to determine whether flowcoating is the optimal process for a given application. For several manufacturers of automotive headlamp lenses and exterior trim components, flowcoating has been the process of choice.