Method of forming composite coating film

Abstract

The present invention provides a method of forming a composite coating film which makes it possible to attain both appearance and workability in a high-humidity environment. The method of forming a composite coating film according to the present invention comprises applying a water-based base coat composition on a substrate, and then a clear coat thereon, wherein said water-based base coat composition comprises a pigment and a resin emulsion obtained by emulsion polymerization of an α, β-ethylenically unsaturated monomer mixture, said α, β-ethylenically unsaturated monomer mixture having an acid value of 3 to 50 and containing at least 65% by weight of a (meth)acrylic ester whose ester moiety contains 1 or 2 carbon atoms.

1 . A method of forming a composite coating film comprising applying a water-based base coat composition to a substrate and then applying a clear coat composition thereonto, 
 wherein said water-based base coat composition comprises a pigment and a resin emulsion obtained by emulsion polymerization of an α, β-ethylenically unsaturated monomer mixture,    said an α, β-ethylenically unsaturated monomer mixture having an acid value of 3 to 50 and containing at least 65% by weight of a (meth)acrylic ester whose ester moiety contains 1 or 2 carbon atoms.    
     
     
         2 . The method of forming a composite coating film according to  claim 1   wherein the hydroxyl value of said α, β-ethylenically unsaturated monomer mixture is 10 to 150.    
     
     
         3 . The method of forming a composite coating film according to  claim 1  or  2  
 wherein said emulsion polymerization is carried out in 2 stages.  
 
     
     
         4 . The method of forming a composite coating film according to any of  claims 1  to  3  
 wherein said pigment is a luster pigment.  
 
     
     
         5 . The method of forming a composite coating film according to any of  claims 1  to  4  
 wherein said water-based base coat composition comprises a curing agent.  
 
     
     
         6 . The method of forming a composite coating film according to any of  claims 1  to  5  
 wherein said water-based base coating composition comprises a water-soluble acrylic resin.  
 
     
     
         7 . The method of forming a composite coating film according to  claim 6   wherein said water-soluble acrylic resin is obtainable by solution polymerization of a component containing not less than 65 weight % of a (meth) acrylic ester whose ester moiety contains 1 or 2 carbon atoms.    
     
     
         8 . A composite coating film as obtainable by the method according to any of  claims 1  to  7 .