Method of manufacturing lithographic printing plate support

Abstract

Disclosed is a method of manufacturing a lithographic printing plate support having the step of: subjecting an aluminum plate at least to a first electrochemical graining treatment in which a first alternating current is passed through the aluminum plate in a first aqueous solution containing hydrochloric acid and nitric acid and a second electrochemical graining treatment in which a second alternating current is passed through the aluminum plate in a second aqueous solution containing hydrochloric acid in this order to obtain the lithographic printing plate support. By this method, a presensitized plate having excellent scumming resistance and a long press life is obtained.

1 . A method of manufacturing a lithographic printing plate support comprising the step of: 
 subjecting an aluminum plate at least to a first electrochemical graining treatment in which a first alternating current is passed through the aluminum plate in a first aqueous solution containing hydrochloric acid and nitric acid and a second electrochemical graining treatment in which a second alternating current is passed through the aluminum plate in a second aqueous solution containing hydrochloric acid in this order to obtain the lithographic printing plate support.    
     
     
         2 . The method according to  claim 1 , wherein the aluminum plate has a pattern of recessed and protruded portions on a surface thereof.  
     
     
         3 . The method according to  claim 1 , wherein the first alternating current is passed through the aluminum plate in the first electrochemical graining treatment so that a total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm 2 .  
     
     
         4 . The method according to  claim 1 , wherein the second alternating current is passed through the aluminum plate in the second electrochemical graining treatment so that a total amount of electricity when the aluminum plate serves as an anode is 10 to 300 C/dm2.  
     
     
         5 . The method according to  claim 1 , wherein the first aqueous solution used in the first electrochemical graining treatment has a hydrochloric acid concentration of 3 to 30 g/L and a nitric acid concentration of 0.5 to 15 g/L.