Clear coating with composition of acrylic and polyester polycarboxylic acids, polyepoxide and crosslinked resin particles

A method for forming a coated film comprises(1) applying a water or solvent based coating composition on an undercoated or intercoated substrate to form a base coating,(2) applying a clear coating composition thereon to form a clear coating without curing the base coating, and(3) heating and curing both the base coating and clear coating, wherein the clear coating composition comprises as a binder(a) from 10-70% by weight of an acrylic polycarboxylic acid having on average 2 or more carboxyl groups per molecule obtained by copolymerizing an acid anhydride group-containing ethylenically unsaturated monomer with an ethylenically unsaturated monomer having no acid anhydride group, then reacting the resulting copolymer with a monoalcohol;(b) from 5-70% by weight of a polyester polycarboxylic acid having an acid value of from 50-350 mg KOH/g (solid) obtained by reacting a polyester polyol having 3 or more hydroxyl groups with an acid anhydride group-containing compound;(c) from 10-80% by weight of a polyepoxide with both an epoxy group and a hydroxyl group; and(d) crosslinked resin particles prepared in the presence of an amphoteric ionic group-containing polyester.