Chemical conversion coating agent and surface-treated metal

Abstract

It is an object of the present invention to provide a chemical conversion coating agent containing no chromium and capable of applying good chemical conversion treatment which is equal to or more than chemical conversion treatment by zinc phosphate to all metals such as iron, zinc and aluminum. A chemical conversion coating agent comprising: at least one kind selected from the group consisting of zirconium, titanium and hafnium; fluorine; and a water-soluble epoxy compound containing an isocyanate group and/or a melamine group, wherein a content of the at least one kind selected from the group consisting of zirconium, titanium and hafnium in the chemical conversion coating agent is 20 to 10000 ppm in terms of metal, and a content of the water-soluble epoxy compound containing the isocyanate group and/or the melamine group in the chemical conversion coating agent is 5 to 5000 ppm as a concentration of solid matter.

1 . A cation electrocoating method comprising:
 pre-treating a substance comprising an iron material at least in part by employing a chemical conversion coating agent comprising   at least one kind selected from the group consisting of zirconium, titanium and hafnium; fluorine; and   an amine group-containing water-soluble epoxy compound having an isocyanate group,   wherein a content of the at least one kind selected from the group consisting of zirconium, titanium and hafnium in the chemical conversion coating agent is 20 to 10000 ppm in terms of metal, and   the amino group-containing water-soluble epoxy compound having an isocyanate group is obtained by allowing an epoxy compound selected from the group consisting of bisphenol F epichlorohydrin type epoxy compound containing an amino group and bisphenol A epichlorohydrin type epoxy compound containing an amino group to react with partially blocked polyisocyanate, and a content of the amino group-containing water-soluble epoxy compound having an isocyanate group in the chemical conversion coating agent is 5 to 5000 ppm as a concentration of solid matter and wherein the pH of the agent is 1.5 to 6.5;   followed by water rinsing the pretreated substance and applying a cation electrocoating.   
   
   
       2 . The method according to  claim 1  wherein the chemical conversion coating agent further contains 1 to 5000 ppm of at least one kind of a chemical conversion reaction accelerator selected from the group consisting of nitrite ions, nitro group-containing compounds, hydroxylamine sulfate, persulfate ions, sulfite ions, hyposulfite ions, peroxides, iron (III) ions, citric acid iron compounds, bromate ions, perchlorinate ions, chlorate ions, chlorite ions as well as ascorbic acid, citric acid, tartaric acid, malonic acid, succinic acid and salts thereof. 
   
   
       3 . The method according to  claim 1  wherein the chemical conversion coating agent further contains at least one kind selected from the group consisting of at least one kind of metal ions (A) selected from the group consisting of zinc ions, magnesium ions, calcium ions, aluminum ions, manganese ions and iron ions; copper ions (B); and a silicon-containing compound (C). 
   
   
       4 . The method according to  claim 3 , wherein the silicon-containing compound (C) is at least one kind selected from the group consisting of silica, water-soluble silicate compounds, esters of silicic acid, alkyl silicates and silane coupling agents.