UNDERCOAT COMPOSITION

摘要

An undercoat composition for a powder coating of a heat-resistance resin on a metal substrate at a high coating temperature is provided. The composition includes a specific imide prepolymer having the formula: <IMG> wherein R1 is an aromatic tetracarboxylic acid residue; R2 is an aromatic diamine residue; R3 is an unsaturated acid anhydride residue which does not include an acetyl group; and ? is an integer and the mean value of ? is within the range of 0 to 5.