Metal surface treatment composition, metal surface treatment method, and galvanized steel plate

Abstract

It is an object of the present invention to provide a metal surface treatment composition and a metal surface treatment method superior in stability, which can apply a good chemical conversion treatment to a galvanized steel plate without requiring a burden of waste water treatment, and a galvanized steel plate superior in a rust-preventive property and adhesion, which is obtained by such a metal surface treatment method. A metal surface treatment composition comprising niobium oxide colloidal particles, wherein the niobium oxide colloidal particles are derived from a niobium oxide sol which is stabilized by containing citric acid or salts thereof in an amount of 0.02 to 1.0 by a mole ratio relative to Nb.

1 . A metal surface treatment composition comprising niobium oxide colloidal particles, 
 wherein the niobium oxide colloidal particles are derived from a niobium oxide sol which is stabilized by containing citric acid or salts thereof in an amount of 0.02 to 1.0 by a mole ratio relative to Nb.    
     
     
         2 . The metal surface treatment composition according to  claim 1 , 
 wherein the niobium oxide colloidal particle has an average particle diameter of 100 nm or less.    
     
     
         3 . The metal surface treatment composition according to  claim 1  or  2 , 
 wherein the niobium oxide colloidal particle has a content of 1 mass % or more relative to the total nonvolatile matter in the metal surface treatment composition when Nb contained in the niobium oxide colloidal particle is converted to equivalent Nb 2 O 5 .    
     
     
         4 . The metal surface treatment composition according to  claim 1  or  2 , comprising 
 a water-borne resin in an amount of 5 to 90 mass % relative to the total nonvolatile matter in the metal surface treatment composition.    
     
     
         5 . The metal surface treatment composition according to  claim 4 , 
 wherein the water-borne resin is at least one kind selected from the group consisting of acrylic resin, polyolefinic resin, polyurethane resin, epoxy resin, olefin-acrylic acid copolymer resin, phenolic resin, polyester resin, alkyd resin, melamine resin, polycarbonate resin, polyacrylic acid and copolymers or block polymers thereof.    
     
     
         6 . The metal surface treatment composition according to  claim 1  or  2 , comprising 
 water-dispersible silica in an amount of 80 mass % or less relative to the total nonvolatile matter in the metal surface treatment composition.    
     
     
         7 . The metal surface treatment composition according to  claim 1  or  2 , comprising 
 at least one compound selected from the group consisting of vanadium compounds, zirconium compounds and titanium compounds in an amount of 0.1 to 30 mass % on the V, Zr or Ti basis relative to the total nonvolatile matter in the metal surface treatment composition.    
     
     
         8 . The metal surface treatment composition according to  claim 1  or  2 , comprising 
 a silane coupling agent in an amount of 0.5 to 30 mass % relative to the total nonvolatile matter in the metal surface treatment composition.    
     
     
         9 . The metal surface treatment composition according to  claim 1  or  2 , comprising 
 a phosphate compound in an amount of 0.1 to 20 mass % relative to the total nonvolatile matter in the metal surface treatment composition.    
     
     
         10 . The metal surface treatment composition according to  claim 1  or  2 , 
 wherein pH is 6 to 11.    
     
     
         11 . The metal surface treatment composition according to  claim 1  or  2 , 
 wherein the concentration of the nonvolatile matter is 3 to 50 mass % on the mass of the nonvolatile matter basis.    
     
     
         12 . A metal surface treatment method 
 applying surface treatment to a galvanized steel plate with the metal surface treatment composition according to  claim 1  or  2 , thereby forming a coat thereof.    
     
     
         13 . A coated galvanized steel plate obtained by the metal surface treatment method according to  claim 12.