Patent ID: 6764587
Filing Date: 2004-07-20
Classification: B41N,C22C

Abstract:
A process for producing an aluminum support for a planographic printing plate, comprising at least two electrochemically surface roughening steps of electrochemically surface-roughening an aluminum plate in an aqueous acidic solution using an alternating current,wherein in each of the electrochemically surface-roughening steps, a ratio QC/QA of a cathode-time quantity of electricity of said aluminum plate QC to an anode-time quantity of electricity of said aluminum plate QA is from 0.95 to 2.5, a duty nib of said alternating current is from 0.25 to 0.5, a frequency of said alternating current is from 30 to 200 Hz, said aqueous acidic solution is an aqueous acidic solution whose principal components are hydrochloric acid and aluminum chloride, wherein the aluminum plate has been prepared from a scrap aluminum or secondary metal containing aluminum in a content of 95 to 99.4 mass % and at least five elements selected from the group consisting of Fe, Si, Cu, Mg, Mn, Zn, Cr and Ti in the following content ranges; Fe: 0.3 to 1.0 mass %;Si: 0.15 to 1.0 mass %;Cu: 0.1 to 1.0 mass %;Mg: 0.1 to 1.5 mass %;Mn: 0.1 to 1.5 mass %;Zn: 0.1 to 0.5 mass %;Cr: 0.01 to 0.1 mass %; andTi: 0.03 to 0.5 mass %,wherein in the respective electrochemically surface-roughening steps, at least one factor selected from the group consisting of the duty ratio of the alternating current, the frequency of the alternating current, the rate QC/QA, the cathode-time quantity of electricity, the anode-time quantity of electricity, a composition of the aqueous acidic solution, a temperature of the aqueous acidic solution and a current density of the alternating current is different.