Process for forming coating film

A process for forming a coating film comprising coating, onto a substrate, a solvent type coating material prepared by blending a color pigment or combination of a metallic powder and a color pigment into a base resin containing a carboxylic acid amide copolymer as the main component, and 1-20 parts by weight of cellulose acetate butyrate resin per 100 parts by weight of the carboxylic acid amide copolymer, then coating a transparent thermosetting powder coating material thereon, and thereafter heating and curing them, wherein said carboxylic acid amide copolymer is one selected from the group consisting of:

• (A) a copolymer comprising 2-20% by weight of .alpha.,.beta.-monoethylenic unsaturated carboxylic acid amide, 0.5-10% by weight of an .alpha.,.beta.-unsaturated carboxylic acid having one or more carboxyl groups, 5-30% by weight of an unsaturated polyester resin and 92.5-40% by weight of other copolymerizable monomer, one hydrogen atom in its amide group being substituted by a group represented by the following formula:
• ##STR3## wherein R represents hydrogen atom or alkyl group and R.sub.1 represents hydrogen atom or organic group;
• and (B) a copolymer comprising 4-40% by weight of N-alkoxyalkyl-substituted amide represented by the following formula:
• ##STR4## wherein R.sub.2 is aliphatic hydrocarbon group having 2-6 carbon atoms and a single, polymerizable, .alpha.,.beta.-ethylenic, unsaturated terminal group and R.sub.3 represents lower alkyl group having 1-8 carbon atoms, 0.5-10% by weight of an .alpha.,.beta.-unsaturated carboxylic acid having one or more carboxylic groups, 5-30% by weight of an unsaturated polyester resin and 90.5-20% by weight of other copolymerizable unsaturated monomer.