WATER-BASED INTERMEDIATE COATING COMPOSITION AND METHOD FOR THE FORMATION OF MULTILAYER COATING FILM

摘要

A water-based intermediate coating composition comprising (A) a resin bearing hydroxyl groups and carboxyl groups which has a hydroxyl number of 100 to 200mgKOH/g and an acid value of 20 to 50mgKOH/g, (B) at least one curing agent selected from the group consisting of melamine resins and blocked polyisocyanates, and (C) flaky pigment particles, in which the curable resin component consisting of the components (A) and (B) has a molecular weight distribution where the content of components having molecular weights of less than 1,000 is 30 to 50% by weight and the content of components having molecular weights exceeding 100,000 is less than 10% by weight and the content of the component (C) is 2 to 15 parts by weight per 100 parts by weight of the resin component and which exhibits a film thickness shrinkage factor of 20% or below as observed when the composition is applied on a primer coat, pre-dried at 100°C for 30 min, and then cured under heating at 145°C for 30 min and based on the film thickness after the pre-drying; and a method for the formation of multilayer coating film with the composition.