Effect of nano layered silicates on automotive polyurethane refinish clear coat

In the present investigation, effect of nano layered silicates on the properties of an automotive refinish clear coat based on polyurethane has been studied. Observation by means of X-ray diffraction (XRD) technique indicates the presence of a partially intercalated structure due to dispersion of nano layers in the polymer matrix. Some levels of hazing have been established by increasing the amount of nano-filler. The effect of nano-filled clear coat on the reflectance spectra of a metallic coated substrate has been studied under three different light sources using a goniospectrophotometer and compared with a blank clear coat to determine if it can be identified by human eye. Scratch and mar resistance tests showed significant improvement even 48 h after application, when there was no gloss reduction due to usage of nano-filler. Gloss retention was increased by about 10% in presence of only 3 wt% of nano-filler. In addition to some scratch and mar resistance tests, other standard tests like adhesion, impact and bending were performed to find out optimum nano-filler/polymer ratio.