Method of forming multi-layer coatings on automobile bodies without a primer bake

A method for forming a multi-layer coating comprising

• sequentially applying a layer of a primer coating composition, a layer of a base coating composition and a layer of a clear coating composition on a substrate;
• and
• simultaneously curing the applied three layers by baking, wherein the primer coating composition comprises:
• a film forming binder and an organic liquid carrier, and optionally pigment in a pigment to binder weight ratio of about 1:100-150:100;
• and the binder contains about:
• (a) 40 to 95% by weight, based on the weight of the binder, of a caprolactone modified linear acrylic polymer having a hydroxyl and/or carboxyl monomer content, all or part of which is reacted with a cyclic lactone, of about 1 to 90% by weight and a weight average molecular weight of about 10,000 to 150,000;
• and
• (b) 5 to 60% by weight, based on the weight of the binder of a crosslinking agent selected from the group consisting of an aminoplast resin, blocked polyisocyanate resin, or a mixture thereof.