Method of producing tinned steel sheets

Abstract

A method of producing a tinned steel sheet that includes forming an Sn-containing plating layer on at least one surface of a steel sheet with a mass per unit area of Sn is 0.05 to 20 g/m 2 ; immersing the steel sheet in a chemical conversion solution containing 60 g/L or more and 200 g/L or less of aluminum phosphate monobasic and which has a pH of 1.5 to 2.4 or cathodically electrolyzing the steel sheet at a current density of 10 A/dm 2 or less in the chemical conversion solution; and drying the steel sheet to form a chemical conversion coating.

1 . A method of producing a tinned steel sheet comprising:
 forming an Sn-containing plating layer on at least one surface of a steel sheet with a mass per unit area of Sn is 0.05 to 20 g/m 2 ;   immersing the steel sheet in a chemical conversion solution containing 60 g/L or more and 200 g/L or less of aluminum phosphate monobasic and which has a pH of 1.5 to 2.4 or cathodically electrolyzing the steel sheet at a current density of 10 A/dm 2  or less in the chemical conversion solution; and   drying the steel sheet to form a chemical conversion coating.   
     
     
         2 . The method according to  claim 1 , wherein the Sn-containing plating layer is a plating layer consisting of a Sn layer or a plating layer consisting of an Fe—Sn layer and a Sn layer deposited thereon. 
     
     
         3 . The method according to  claim 1 , wherein drying is performed at a temperature of lower than 60° C. 
     
     
         4 . The method according to  claim 1 , wherein cathodic electrolyzing is performed such that the temperature of the chemical conversion solution is adjusted to 70° C. or higher. 
     
     
         5 . The method according to  claim 1 , wherein the steel sheet is subjected to the immersing or the cathodic electrolyzing for less than 1 second.