Nippon Paint Compnay, Ltd.

Toyota Jidosha Kabushiki Kaisha

Kouki Hayashi

Teruaki Kuwajima

Hiroharu Ohsugi

Junya Ogawa

Atsuo Magoshi

Daichi Kato

The present invention relates to a method for producing a multilayer coating film, which comprises 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; applying a clear coating composition on the base coating film to form a clear coating film; 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 27 to 65% by weight of a styrene monomer, 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): R&#x2014;(OA)-O&#x2014;C(&#x2550;O)&#x2014;NH&#x2014;Y&#x2014;NH&#x2014;C(&#x2550;O)&#x2014;O-(AO)&#x2014;R (1) R&#x2014;(OA)-[O&#x2014;C(&#x2550;O)&#x2014;NH&#x2014;Y&#x2014;NH&#x2014;C(&#x2550;O)&#x2014;(OA)]-O&#x2014;C(&#x2550;O)&#x2014;NH&#x2014;Y&#x2014;NH&#x2014;C(&#x2550;O)&#x2014;O-(AO)&#x2014;R (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&#xd7;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, in order to provide the multilayer coating film with an excellent exterior appearance by a three coating and one baking (3C1B) procedure, wherein viscosity of the intermediate coating composition is controlled, and furthermore, ratio of hydrophilicity to hydrophobicity of the resin in the intermediate coating composition is controlled, in order to significantly suppress sagging of the waterborne intermediate coating composition during the coating procedure.

Method for forming multilayer coating films wherein the basecoat film comprises acrylic, polyester and melamine resins, carbodiimide and urethane thickeners

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 &agr;, &bgr;-ethylenically unsaturated monomer mixture, said &agr;,&bgr;-ethylenically unsaturated monomer mixture having an acid value of 3 to 50 mg KOH/g and containing at least 65% by weight of a (meth)acrylic ester whose ester moiety contains 1 or 2 carbon atoms.

Method of forming a composite coating film comprising a pigment and resin emulsion

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Aichi, Japan

Kouki Hayashi