Clear coating composition for an automobile and method of forming a multi-layer coating film using the same

摘要

An automotive clear coating composition includes a hydroxyl group-containing acrylic resin obtained using hydroxyalkyl(meth)acrylate having a hydroxyalkyl group having 4-9 carbon atoms as at least a part of its monomer; and a polyfunctional isocyanate compound in which at least a part thereof is an isocyanurate type isocyanate compound. The prepared composition has 25 to 50 mass % of a soft segment part with respect to a total solid content of such acrylic resin and the polyfunctional isocyanate compound, and a ratio of a soft segment part derived from a lactone-containing monomer with respect to the total solid content of such acrylic resin and the polyfunctional isocyanate compound of not more than 4.5 mass %. A cured coating film has a dynamic glass transition temperature within a range of 30 to 60° C. The soft segment part is represented by —CH2)n— wherein n represents an integer of 4 or more.