UV Processing Effects on Polycarbonate

摘要

Polycarbonate films are used in a variety of screenprinting applications including membrane switch overlays, automotive instrument clusters, and graphic arts. Historically, solvent based inks have been used to decorate the film surfaces. Environmental concerns about solvent emissions have resulted in the increased use of UV curable ink systems for these applications by the screenprinting community. The adhesion of the ink to the polycarbonate surface is affected by a number of factors, including the type of ink, the ink components or additives, printing or processing conditions, the substrate surface conditions and the UV process itself. Most product applications require multiple colors and textures and as such, multiple exposures of the film surface to UV eneergy. Our studies have established that multiple exposures of polycarbonate film to UV irradiation below 320 nm results in a gradual degradation of the film surface. In the worse cases, this degradation leads to a complete loss of UV ink adhesion. In this presentation, we plan to discuss these factors and some practical alternatives to address these issues. In addition, we will present information on some typical ink components and additives which can lead to UV ink adhesion issues.