Abstract: A support material made from aluminum or an aluminum alloy for printing plates has a prestamped surface. The prior stamping comprises hemispherical indentations with a diameter of from 2 to 50 &mgr;m and a mean diameter of 20 to 30 &mgr;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 aluminum salt. The current density of the alternating current is 30 to 45 A/dm2. The surface roughness RA after roughening is uniform, covers the entire area and lies in the range from 1.0 to 1.5 &mgr;m.

Abstract: A ceramic layer comprising aluminum oxide and a silicate compound is applied to a substrate of a printing plate, with the silicate compound acting as a binder to ensure adhesion of the ceramic layer to the substrate.

Abstract: A mechanically and/or electrochemically grained and optionally anodized base material composed of aluminum or its alloys, to which a hydrophilic layer of at least one polymer containing basic and acidic groups is applied. This layer is followed by a further hydrophilic layer which contains at least one compound containing at least one phosphono group. In addition, the invention relates to a method of producing said carrier material and to photosensitive recording material for offset printing plates produced therewith.

Abstract: Grained, anodized and hydrophilized lithographic printing plates which have a negative or positive working radiation-sensitive coating, are exposed and are developed in an aqueous alkaline solution, are subjected, after hydrophilization, to a treatment with a salt solution containing divalent or polyvalent cations in a concentration of not less than 0.02 mol/l, thereby minimizing degradation of the plate and contamination of the printing forms and the development apparatus.

Abstract: A process for roughening aluminum or aluminum alloys useful as support material for printing plates, in which process two electrochemical roughening steps are carried out in direct succession and are followed by a pickling step. Printing plates are produced from this support material by coating with light-sensitive coatings, which printing plates, when exposed and developed, give corresponding printing formes of very uniform topography, high run stability and good damping agent supply.

Abstract: A process for roughening aluminum or alloys thereof for printing plate supports, wherein an electrochemical roughening is performed by means of alternating current in an acidic electrolyte including sulfate ions and chloride ions, the chloride ions being in the form of aluminum chloride. In a preceding or subsequent rougheniong stage, mechanical roughening and/or electrochemical roughening by means of alternating current in an electrolyte is carried out. The electrolyte can include hydrochloric acid and aluminum ions, nitric acid and aluminum ions or sulfuric acid and chloride ions.

Abstract: There is disclosed a plate-, foil- or web-shaped support material for offset printing plates, made of mill-finished, mechanically and/or chemically or mechanically and electrochemically grained aluminum or an aluminum alloy, which has been anodized in aqueous-alkaline solutions. The support material of the invention shows a reflectometer value, at an angle of incidence of 60.degree. (measured according to DIN 67 530; 1982), of greater than 5, an abrasion of the oxide layer of less than 0.5 g/m.sup.2 and a resistance to alkali of greater than 140 s. Also disclosed is a process for the manufacture of the support material, in which an anodic oxidation is carried out in an electrolyte having a pH greater than or equal to 12.5, at a voltage of less than 50 V.

Abstract: 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 H.sub.2 SO.sub.4 and contains H.sub.3 PO.sub.4 and Al.sup.+3 ions is used. The process parameters are: an electrolyte content of 25 g/l to 500 g/l of H.sub.3 PO.sub.4 and at least 5 g/l of Al.sup.+3 ions, a treatment time of 5 seconds to 500 seconds, a current density of 1 A/dm.sup.2 to 30 A/dm.sup.2 and a temperature of 35.degree. C. to 95.degree. C. The Al.sup.+3 ion source in particular is a salt of aluminum having a phosphoroxo anion, such as AlPO.sub.4. 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.