Coating composition for forming titanium oxide film, process for forming titanium oxide film and metal substrate coated with titanium oxide film

Abstract

The present invention provides a coating composition for forming a titanium oxide film, comprising (A) a specific titanium-containing aqueous liquid and (B) at least one compound selected from the group consisting of organic acids and their salts. The present invention also provides a process for forming a titanium oxide film using the coating composition, and a metal substrate coated therewith.

1 . A coating composition for forming a titanium oxide film; comprising: 
 (A) a titanium-containing aqueous liquid obtained by mixing at least one titanium compound selected from the group consisting of titanium hydroxide and its condensates having a condensation degree of 2 to 30, with aqueous hydrogen peroxide; and    (B) at least one compound selected from the group consisting of organic phosphoric acids and their salts.    
     
     
         2 . A coating composition according to  claim 1 , wherein the compound (B) is at least one compound selected from the group consisting of hydroxyl-containing organic phosphorous acids, carboxyl-containing organic phosphorous acids and salts of these acids.  
     
     
         3 . A coating composition according to  claim 1 , wherein the proportion of the compound (B) is 1 to 400 parts by weight per 100 parts by weight of the solids in the titanium-containing aqueous liquid (A).  
     
     
         4 . A coating composition according to  claim 1 , which is an aqueous liquid having a pH of 1 to 10.  
     
     
         5 . A coating composition according to  claim 4 , which is an aqueous liquid having a pH of 1 to 9.  
     
     
         6 . A coating composition according to  claim 1 , which further comprises an inorganic phosphoric acid compound.  
     
     
         7 . A coating composition according to  claim 1 , which further comprises at least one halide selected from the group consisting of titanium halides, titanium halide salts, zirconium halides, zirconium halide salts, silicon halides and silicon halide salts.  
     
     
         8 . A coating composition according to  claim 1 , which further comprises an aqueous organic compound selected from the group consisting of epoxy resins, phenol resins, acrylic resins, urethane resins, polyvinyl alcohol resins, polyoxyalkylene chain-containing resins, olefin-polymerizable unsaturated carboxylic acid copolymer resins, nylon resins, polyglycerin, carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose.  
     
     
         9 . A process for forming a titanium oxide film, comprising applying a coating composition according to  claim 1  to a metal substrate, followed by drying.  
     
     
         10 . A coated metal substrate comprising a metal substrate and a film of a coating composition according to  claim 1  formed on a surface of the substrate.  
     
     
         11 . A coated metal substrate according to  claim 10 , wherein the film has a dry weight of 0.001 to 10g/m 2 .  
     
     
         12 . A coated metal substrate according to  claim 10 , wherein the metal substrate is made of steel.  
     
     
         13 . A coated metal substrate according to  claim 10 , wherein the metal substrate is made of aluminum or an aluminum alloy.