Trivalent chromium plating solution and chromium plating method using same

Abstract

A trivalent chromium plating solution containing a trivalent chromium compound, a complexing agent, a conductive salt, and a pH-buffering agent, and further containing an organic compound having 2-4 carbon atoms and three or more chloro groups, and a trivalent chromium plating method using the same provide a practical trivalent chromium plating with enhanced corrosion resistance as compared to the ordinary trivalent chromium plating.

1 . A trivalent chromium plating solution, comprising:
 a trivalent chromium compound,   a complexing agent,   a conductive salt,   a pH-buffering agent, and   an organic compound having 2-4 carbon atoms and three or more chloro groups.   
     
     
         2 . The trivalent chromium plating solution of  claim 1 , wherein the organic compound having 2-4 carbon atoms and three or more chloro groups is chloral hydrate and/or trichloroethylene. 
     
     
         3 . The trivalent chromium plating solution of  claim 1 , wherein the conductive salt is a sulfate. 
     
     
         4 . The trivalent chromium plating solution of  claim 3 , further comprising a sulfur-containing organic compound. 
     
     
         5 . The trivalent chromium plating solution according to of  claim 4 , wherein:
 the complexing agent is a carboxylic acid having two or more hydroxy groups and two or more carboxy groups or a salt thereof, and   the sulfur-containing organic compound is a combination of saccharin or a salt thereof and at least one selected from the group consisting of a sulfur-containing organic compound having an allyl group and a carboxylic acid having a carbamimidoylthio group and/or a dehydration reaction product thereof.   
     
     
         6 . The trivalent chromium plating solution of  claim 5 , wherein the carboxylic acid having two or more hydroxy groups and two or more carboxy groups or a salt thereof is tartaric acid or diammonium tartrate. 
     
     
         7 . The trivalent chromium plating solution of  claim 5 , wherein the sulfur-containing organic compound having an allyl group is sodium allylsulfonate and/or allylthiourea. 
     
     
         8 . The trivalent chromium plating solution of  claim 5 , further comprising a carboxylic acid having two or more carboxy groups and 4 or more carbon atoms or a salt thereof as the complexing agent. 
     
     
         9 . The trivalent chromium plating solution of  claim 8 , wherein the carboxylic acid having two or more carboxy groups and 4 or more carbon atoms or a salt thereof is phthalic acid and/or adipic acid. 
     
     
         10 . The trivalent chromium plating solution of  claim 1 , wherein the conductive salt is a chloride. 
     
     
         11 . An additive for a trivalent chromium plating solution, comprising an organic compound having 2-4 carbon atoms and three or more chloro groups as an active ingredient. 
     
     
         12 . A chromium plating method for an article to be plated, comprising electroplating the article to be plated with the trivalent chromium plating solution of  claim 1 . 
     
     
         13 . The chromium plating method of  claim 12 , further comprising performing a chromate treatment after the electroplating the article to be plated. 
     
     
         14 . A method for enhancing corrosion resistance of an article to be plated, comprising electroplating the article to be plated with the trivalent chromium plating solution of  claim 1 . 
     
     
         15 . The method of  claim 14 , further comprising performing a chromate treatment after the electroplating the article to be plated. 
     
     
         16 . A chromium plated product obtained by electroplating an article to be plated with the trivalent chromium plating solution of  claim 1 .