To provide a manufacturing method for an aluminum substrate for a lithographic printing plate which makes it possible to use an aluminum rolled sheet (an aluminum sheet containing lots of alloy constituents or an aluminum sheet of which the alloy constituents are not regulated) and which brings about no nonuniformity in treatment due to surface roughening treatment and can make compatible plate wear and printing performance (scumming performance) when it is made into the plate.
In this manufacturing method, the aluminum sheet is subjected sequentially to (1) electrochemical surface roughening treatment in a nitric acid water solution in the condition that the ratio Qc/Qa between the quantity Qa of electricity of an alternating current on the occasion of the aluminum sheet being an anode and the quantity Qc of electricity of the current on the occasion of the sheet being a cathode is 0.9-1.0, (2) electrochemical surface roughening treatment in a hydrochloric acid water solution wherein the concentration of aluminum ions is made 1-8 g/L by adding an aluminum chloride hexahydrate in the rate of 10-70 g/L to a water solution containing a hydrochloric acid of 1-10 g/L, in the condition that the ratio of Qc/Qa is 0.9-1.0, and (3) anodizing treatment.
SAWADA HIROKAZU
UESUGI AKIO
