COMPOSITE PAINT FILM

摘要

The composite paint film comprises an electrodeposition paint film (I), coated on a sheet-steel automotive outer panel, and an intermediate coat paint film (II) coated on the first paint film. The electrodeposition paint film (I) is formed of epoxy-based cationic electrodeposition paint composition and has a minimum melt viscosity ( lambda min) not less than 0.2 during hardening. The epoxy-based composition includes an amine-added epoxy resin (1) of the type hardened with a blocked isocyanate, a colloidal silica-containing gelled particulate (2), and an alkyltin ester compound (3) of a liquid aliphatic carboxylic acid. The gelled particulate (2) is formed by dispersing a mixture of an acrylic copolymer, having a hydrolizable alkoxysilane group and a cationic group, and a cationic acidic colloidal silica in a water to carry out cross-linking reaction in particles of the colloidal silica. The second paint film (II) has a hardening starting time ranging from 15 to 20 minutes.