Patent CA-2635478-A1 (CA)
Title: Method for producing multi layered coating film
Inventor: NITTA TETSUJI
IPC: B05D1/36
Filed: 2008-06-20
Abstract: The present invention relates to a method for producing a multi layered coating film, which comprises steps of:   applying an intermediate coating composition on an article to form an intermediate coating thereon;   applying a metallic color base coating composition on the intermediate coating to form a metallic color base coating thereon; and applying a clear coating composition on the metallic color base coating to form a clear coating thereon;   wherein the metallic color base coating composition is waterborne and comprises an acryl emulsion resin;   a water dispersion of a hydrophobic melamine resin having an average particle size within a range of from 20 to 300 nm;   a luster color pigment; and an organic alcohol solvent having a solubility in water within a range of from 0.01 to 5.0 wt% and a boiling point within a range of from 160 to 200°C, which is comprised within a range of from 5 to 45 wt% relative to solid resin content of the coating composition as a basis of weight; and wherein the water dispersion of a hydrophobic melamine resin is obtained/obtainable by a method comprising steps of:  mixing an acryl resin and a hydrophobic melamine resin in a weight ratio of the acryl resin to the hydrophobic melamine resin within a range of a ratio of from 5/95 to 25/75 [acryl resin/hydrophobic melamine resin (as a basis of solid content)], wherein the acryl resin has an acid value within a range of from 105 to 200 mgKOH/g, a hydroxyl value within a range of from 50 to 200 mgKOH/g and a number average molecular weight within a range of from 1000 to 5000; and reacting the acryl resin and the hydrophobic melamine resin at a temperature within a range of from 70 to 100°C for 1 to 10 hours.     The present invention can provide the method for producing the multi layered coating film, which can prevent aggregate due to agglomeration of luster color pigment, and the waterborne metallic color base coating composition applicable to the method.     The present invention also relates to a method for producing a multi layered coating film, which comprises steps of:   applying an intermediate coating composition on an article to form an intermediate coating thereon;   applying a metallic color base coating composition on the intermediate coating to form a metallic color base coating thereon; and applying a clear coating composition on the metallic color base coating to form a clear coating thereon;   wherein the metallic color base coating composition is waterborne and comprises an acryl emulsion resin;   a curing agent of a melamine resin;  a luster color pigment;   a surfactant comprising a reaction product obtained/obtainable by a reaction of (a1) a nonreducing disaccharide or trisaccharide and (a2) an alkyleneoxide having 2 to 4 carbon atoms; and an organic alcohol solvent having a solubility in water within a range of from 0.01 to 5.0 wt% and a boiling point within a range of from 160 to 200°C, and/or an organic glycol-ether solvent having a solubility in water within a range of from 0.01 to 5.0 wt% and a boiling point within a range of from 205 to 240°C, each of which is comprised within a range of from 5 to 45 wt% relative to solid resin content of the coating composition as a basis of weight.     The present invention further relates to the waterborne metallic color base coating composition to be used in the above-described method for producing the multi layered coating film.     The present invention can provide the method for producing the multi layered coating film, which can suppress and/or prevent skinning and aggregate due to agglomeration, and the waterborne metallic color base coating composition applicable to the method.