Process for roughening support material for printing plates

摘要

A support material made from aluminium or an aluminium alloy for printing plates has a prestamped surface. The prior stamping comprises hemispherical indentations with a diameter of from 2 to 50 mu m and a mean diameter of 20 to 30 mu m. This support material is electrochemically roughened in an electrolyte which is selected from the group consisting of hydrochloric acid, nitric acid, sulphuric acid and chloride or nitrate ions of an aluminium salt. The current density of the alternating current is 30 to 45 A/dm<2>. The surface roughness RA after roughening is uniform, covers the entire area and lies in the range from 1.0 to 1.5 mu m.