Removal of coatings from polymer substrates by solid particle blasting to enhance reuse or recycling

In the automotive industry, polymer components are routinely employed in a wide variety of situations. Where such components are employed in visible applications, their aesthetic appeal is commonly enhanced by the application of surface coatings, such as paints or chrome plate. However, throughout the lifecycle of the component, coating removal may be required to enhance its ability to be reused or recycled. For example, following the coating processes, it is commonly found that a significant number of components fall below the quality specified and as such remedial action is required. There are a number of routes available: (i) recycling of the component in the as-coated state; (ii) recycling of the component following removal of the coating, allowing a higher value product to be realised; (iii) recoating of the component following removal of the defective coating. The last of these options has restrictions on the surface roughness of the substrate following coating removal. Again, at the end of component life, the recovery of high value material may be enhanced by the removal of coatings, although here, the surface condition of the substrate is not an issue of concern. This paper examines the use of solid particle blasting with spherical glass particles as a means of coating removal for two industrially relevant systems, namely paint coatings on polypropylene blend substrates and chrome coatings on ABS substrates. It was found that paint could be removed from the substrates, but that a very large dose of particles was required. The high compliance of both the coating and the substrate resulted in the difficulty in removing the paint films. In contrast, the chrome coatings could successfully be removed from the ABS substrates at low particle doses. The possibility of recoating of the ABS substrates following coating removal was assessed in light of the roughness developed by the removal of the coating.