Patent ID: 9376574
Filing Date: 2016-06-28
CPC Classification: B05D,C08F,C09D

Claim Text:
1. A method for producing a multilayer coating film, which comprises the steps of applying a waterborne intermediate coating composition on an electrodeposited coating film to form an intermediate coating film; applying a waterborne base coating composition on the intermediate coating film to form a base coating film, wherein the waterborne base coating composition comprises a film forming resin selected from the group consisting of a polyester resin and an acrylic resin; applying a clear coating composition on the base coating film to form a clear coating film, wherein the clear coating composition comprises a film forming resin selected from the group consisting of an acrylic resin and a polyester resin; and simultaneously baking and curing the intermediate coating film, the base coating film applied thereon, and the clear coating film further applied thereon in order to form a multilayer coating film, wherein the waterborne intermediate coating composition comprises an emulsion of a hydroxyl group-containing acrylic resin comprising 35 to 45% by weight of a styrene monomer, relative to total weight of monomers for preparation of the acrylic resin of the emulsion, wherein the emulsion has a water-tolerance within a range of from 0.2 to 5 and a hexane-tolerance within a range of from 5 to 25; a hydroxyl group-containing polyester resin; a melamine resin; a carbodiimide; and an associative thickener, wherein the associative thickener comprises an urethane compound (A) represented by the formula (1), and an urethane compound (B) represented by the formula (2): wherein R independently represents a hydrocarbon group having 8 to 24 carbon atoms, Y independently represents a residue resulted from a removal of two isocyanate groups from a diisocyanate, OA independently represents an oxyalkylene group having 2 to 4 carbon atoms, AO independently represents an alkyleneoxy group having 2 to 4 carbon atoms, O represents an oxygen atom, C represents a carbon atom, N represents a nitrogen atom, m independently represents an integer of 20 to 500, n independently represents an integer of 20 to 500, a independently represents an integer of 1 to 100, d independently represents an integer of 1 to 100, b represents an integer of 40 to 500, c represents an integer of 1 to 5, b by c (or b×c) represents an integer of 150 to 2500, and R may be the same or different, and Y may be the same or different, wherein each of the urethane compounds (A) and (B) has at least 80% by weight of oxyethylene groups and ethyleneoxy groups relative to the total weight of the oxyalkylene groups and the alkyleneoxy groups, wherein weight ratio of the hydroxyl group-containing acrylic resin emulsion to the associative thickener is within a range of from 100/0.1 to 100/50 as a basis of the solid content, and wherein the waterborne intermediate coating composition comprises 3 to 25% by weight of the carbodiimide.