VERFAHREN ZUR ANODISCHEN OXIDATION VON ALUMINIUM UND DESSEN VERWENDUNG ALS TRAEGERMATERIAL FUER OFFSETDRUCKPLATTEN.

摘要

In the process for the anodic oxidation of mechanically, chemically and/or electrochemically roughened aluminum or of one of its alloys, an aqueous electrolyte, which is free from H2SO4 and contains H3PO4 and Al+3 ions is used. The process parameters are: an electrolyte content of 25 g/l to 500 g/l of H3PO4 and at least 5 g/l of Al+3 ions, a treatment time of 5 seconds to 500 seconds, a current density of 1 A/dm2 to 30 A/dm2 and a temperature of 35 DEG C. to 95 DEG C. The Al+3 ion source in particular is a salt of aluminum having a phosphoroxo anion, such as AlPO4. The material prepared in accordance with this invention is preferably employed as a support material for offset printing plates which carry a radiation-sensitive layer.