Control of surface roughness of PET silica gel protective film
Surface roughness is a potential technical indicator of PET silica gel protective film. Surface roughness refers to the comprehensive evaluation of the micro-geometric shape characteristics of the fine peaks and valleys in small intervals on the surface of the film. Surface roughness is expressed by Ra (arithmetic error of contour mean value), Rz (relative height of mean unevenness), and Rt (relative height from peak to valley). Reasonable surface roughness is more conducive to ink printing and vacuum aluminum plating, especially for shallow screen packaging printing. If the surface roughness is too large, it is likely that printing ink molecules or aluminum molecules cannot fill the grooves on the surface of the film, which interferes with the bonding between the two, and may cause delamination in severe cases. The surface roughness of PET silica gel protective film is usually controlled at Rau003d0.08～0.16.