Factors Affecting Gloss and Color of Decorative Pressure Sensitive Adhesive Films During Thermomechanical Deformation

Decorative polymer films are finding applications in processes that require forming at elevated temperatures and significant strain. In order to satisfy their function in these applications, the appearance of these films must remain unaltered or at least any changes must be predictable. This paper examines four different high gloss decorative films comprised of different materials in the layers of their construction. The films were uniaxially stretched up to failure (which was up to 75% strain) at isothermal conditions of 25, 40, or 75 degrees C and then examined. Gloss (at 20 degrees) was the most strongly altered parameter concerning the appearance of the films after thermomechanical deformation while color intensity was relatively unaffected. The change in gloss was higher for the two amorphous films compared to the two that exhibited crystallinity. The films were analyzed for their surface roughness using a white light interferometer, for their crystallinity by X-ray diffraction and for their morphology by atomic force microscopy (AFM). Surface roughness increased with crystallinity for the two films that exhibited crystals but overall showed no correlation to the gloss measurements. Only evidence of altered domain morphology in the films as determined by AFM appeared to correlate with the changes in gloss reported. (C) 2016 Society of Plastics Engineers