Relationship between Curing Characteristics and Rheological/Mechanical Properties of Soft-feel Coatings for Automotive Plastic Parts

Abstract

In order to investigate the properties of soft-feel coating paints for automotive interior plastics, the characteristics of coating systems were systematically determined by changing the main resin composition, isocyanate type cross-linker ratio, and curing temperature conditions. During the thermal curing process, the change in cross-linked network structure of coating systems was analyzed from the rheological properties using a rotational rheometer and curing behaviors of thin coating films were scrutinized by a rigid-body pendulum tester. After finalizing the curing process, the change in the amount of functional groups, according to the ratio (NCO/OH ratio) between main resin and crosslinker, was checked by Fourier transform infrared spectroscopy (FTIR). Also, thermal and mechanical properties of cured films were measured via dynamic mechanical analysis and nano-indentation test. Through these analyses, the relationship between curing characteristics of soft-feel paints during the curing process and various properties of final cured coating films was elucidated.