Abstract:
A process for manufacturing materials in the form of sheets, foils or webs comprising chemically, mechanically and/or electrochemically roughened and anodically oxidized aluminum or one of its alloys, wherein the resultant aluminum oxide layers are post-treated with an aqueous solution containing phosphoroxo anions, is performed such that a post-treatment of the aluminum oxide layers is effected by immersion in an aqueous solution containing hexametaphosphate anion. In a preferred embodiment, the aqueous solution is adjusted to a pH of 1 to 5 by addition of an acid. The resulting materials, which have reduced adsorption properties, are preferably employed as support materials for offset printing plates.
Abstract:
A process for producing chromium-plated, steel-based printing plate carriers comprises (A) simultaneously roughening and partially chromium-plating a substrate using alternating current in an electrolyte containing chromium, chloride, sulfate and, if appropriate, strontium ions and then, in the same electrolyte, (B) employing direct current to effect final chromium-plating. The printing plate supports produced in this manner have a uniform surface topography and peak-to-valley height values that are favorable for coating.
Abstract:
A process for producing an aluminum support for a lithographic printing plate is described, which comprises jetting a high-pressure liquid from at least one nozzle at a high rate, joining the jetted stream with a slurry containing a fine powder of an abrasive spouted from at least one spout, and directing the resulting mixed stream to strike against a surface of an aluminum plate to carry out cleaning and sandblasting at the same time.
Abstract:
A method of preparing an anodized aluminum printing plate comprising treating the aluminum support with aqueous solution of a condensed aryl sulfonic acid having a neutral pH, anodizing the support before or after the treating step, and coat, radiation expose through a mask, as well as develop a radiation-sensitive composition to produce the lithographic printing plate.
Abstract:
An improved photopolymer coated lithographic printing plate having a thin, glasslike and water insoluble film disposed intermediate a photopolymeric coating and a directly electrodeposited layer of chromium on a sheet metal base substrate, and wherein said film comprises the cured residue of an applied zirconium base water solution.
Abstract:
A lithographic printing plate precursor comprises an electrochemically grained aluminium substrate, the grained surface of which is coated with a layer of gel-like amorphous colloidal oxides and hydroxides of aluminium and their hydrates incorporating metallic aluminium and inter-metallic aluminium alloys—generally at a level of below 5%—this layer being produced during the electrochemical graining process. The layer is typically present in an amount of from 0.1-20 g/m2 and at a layer thickness of 0.1-4.0 &mgr;m, the particle sizes in the said layer generally falling in the range of from 10 to 2000 nm. Methods are disclosed for the preparation of said precursors via the electrochemical graining of aluminium substrates. The invention provides lithographic printing plate precursors which may be imagewise exposed by means of a high intensity laser beam to provide printing plates showing high durability on press and giving images which show good resolution and are free from background staining.
Abstract:
A method for preparing a substrate for lithographic printing plates comprises the steps of forming a hydrated oxide layer on the surface of an aluminum plate and then anodizing the plate in a sulfuric acid electrolyte; a lithographic printing plate comprises the substrate; and the substrate per se prepared by the method is also disclosed herein.The presensitized plate for use in making lithographic printing plates which comprises the substrate has very high sensitivity which makes the presensitized plate applicable to new exposure methods and is capable of being developed with a developer of an aqueous solution system. The light-sensitive layer and the substrate of the presensitized plate are strongly adhered to one another and, therefore, the resulting lithographic printing plate has excellent printing durability and good printability.