| 摘要 |
This invention relates to a process of producing an aluminum base offset printing plate including a step wherein the surface of an aluminum base sheet is roughened or grained electrolytically by treating with alternating electric current at a current density of a selected range in an aqueous electrolyte containing hydrogen chloride as the primary etching agent and in the presence of one or more anti-corrosive agents chosen from some selected primary alkyl amine, secondary alkyl amines and tertiary alkyl amines, either un-substituted or substituted by carboxyl or hydroxyl on the alkyl group(s), alkylene diamines, alkyl aldehydes, alkanoic acid amides, urea, chromic acid and known ionic surface-active agents. The presence of the anti-corrosive agent results in an improved uniformity of the grain particle size and prevents the dark colored aluminum smutt from depositing on the grained surface. The electrolytically graining treatment may continuously be performed with a continuous aluminum strip when an electrolytic cell of a particular arrangement as shown in the accompanying drawings is employed and when the treatment is effected in the presence of a mono-alkanol amine, di-alkanol amine, tri-alkanol amine or non-ionic surface active agent derived from polyethylene-glycol as the anti-corrosive agent under particularly more favorable etching conditions.
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