Method of manufacturing lithographic printing plate support

Abstract

A method of manufacturing a lithographic printing plate support having a step of subjecting an aluminum plate to an electrochemical graining treatment in which alternating current is passed through the aluminum plate in an aqueous solution containing at least chloride ion and nitrate ion so that total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm 2 . By this method, a lithographic printing plate support which makes it possible to obtain a presensitized plate having both an excellent scumming resistance and a good press life by a single electrochemical graining treatment.

1 . A method of manufacturing a lithographic printing plate support comprising a step of subjecting an aluminum plate to an electrochemical graining treatment in which alternating current is passed through the aluminum plate in an aqueous solution containing at least chloride ion and nitrate ion so that total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm 2 .  
     
     
         2 . The method of manufacturing a lithographic printing plate support according to  claim 1 , wherein the aqueous solution contains hydrochloric acid and nitric acid.  
     
     
         3 . The method of manufacturing a lithographic printing plate support according to  claim 1 , wherein the aqueous solution has a chloride ion concentration of 3 g/L or more and a nitrate ion concentration of 0.50 g/L or more.  
     
     
         4 . The method of manufacturing a lithographic printing plate support according to  claim 1 , wherein the aqueous solution has a pH of 0.8 or less.  
     
     
         5 . The method of manufacturing a lithographic printing plate support according to  claim 1 , wherein the aqueous solution contains 2 g/L or more of aluminum ions.  
     
     
         6 . The method of manufacturing a lithographic printing plate support according to  claim 1 , wherein the aluminum plate has a pattern of recessed and protruded portions provided on its surface.