Composition for treating surface of metal, method for treating surface of metal using the composition, and coating film for treating surface of metal utilizing the composition and the method

Abstract

A process for metal surface treatment includes dipping a metallic material with a cleaned surface into a composition containing 5 to 30% by weight of a nonionic and/or cationic water-based resin, 100 to 1,000 ppm of trivalent Bi ions, and an aminopolycarboxylic acid at 0.5 to 10 times in molar concentration based on the Bi ions, then performing a first electrolysis using the metallic material as a cathode at a voltage of 0 to 15 V for 10 to 120 seconds, and performing a second electrolysis at a voltage of 50 to 300 V for 30 to 300 seconds, in which the performing the first electrolysis is prior to the performing the second electrolysis, and thereafter rising with water, and baking to deposit a film over the metallic material.

1 . A process for metal surface treatment comprises
 dipping a metallic material with a cleaned surface into a composition comprising
 5 to 30% by weight of a nonionic and/or cationic water-based resin, 
 100 to 1,000 ppm of trivalent Bi ions, and 
 an aminopolycarboxylic acid at 0.5 to 10 times in molar concentration based on the Bi ions, then 
   performing a first electrolysis using the metallic material as a cathode at a voltage of 0 to 15 V for 10 to 120 seconds, and   performing a second electrolysis at a voltage of 50 to 300 V for 30 to 300 seconds, wherein the performing the first electrolysis is prior to the performing the second electrolysis, and thereafter   rising with water, and   baking to deposit a film over the metallic material.   
     
     
         2 . The process for metal surface treatment of  claim 1 , wherein the composition further comprising 20 to 500 ppm of trivalent Al ions. 
     
     
         3 . A process for manufacturing a metal surface treatment film comprises
 dipping a metallic material with a cleaned surface into a composition comprising
 5 to 30% by weight of a nonionic and/or cationic water-based resin, 
 100 to 1,000 ppm of trivalent Bi ions, and 
 an aminopolycarboxylic acid at 0.5 to 10 times in molar concentration based on the Bi ions, then 
   performing a first electrolysis using the metallic material as a cathode at a voltage of 0 to 15 V for 10 to 120 seconds, and   performing a second electrolysis at a voltage of 50 to 300 V for 30 to 300 seconds, wherein the performing the first electrolysis is prior to the performing the second electrolysis, and thereafter   rising with water, and   baking to deposit a film over the metallic material,
 wherein the film having metal Bi and oxidized Bi deposited as Bi at 20 to 250 mg/m 2 , with a total film thickness being from 5 to 40 μm and a distribution of Bi deposition being such that B, which is an amount of deposited Bi from the center of a film thickness to the side of a metallic material, is 55% or more based on A, which is a total amount of deposited Bi (B/A≧55%). 
   
     
     
         4 . The process for manufacturing a metal surface treatment film of  claim 3 , wherein the composition further comprising 20 to 500 ppm of trivalent Al ions.