Abstract: A copper clad metal printing plate can be coated with an azide-containing photoresist comprising a polyformal resin together with a modified polyformal resin that has up to 100% of its hydroxyl groups converted to carboxyl groups, an organo azide and a photosensitive dye that absorbs light at the frequency of a patterning laser and converts it to heat energy. This de-crosslinks the resin that has been exposed to the laser light. Preferably the photoresist is flood exposed with ultraviolet light prior to laser exposure. The photoresist becomes soluble in the laser-exposed areas, exposing the underlying copper after development. The printing plates are completed by etching away the copper in the exposed areas, removing the remaining photoresist, thereby providing a patterned copper layer on the printing plate.

Abstract: A method of making improved aluminum printing plates comprising graining the aluminum plates, de-smutting them by treating them with nitric acid solution, then rinsing with hot water, acetating the aluminum plates, and silicating the aluminum plates. The plates are then coated with a photoresist, pattern exposed and developed. The printing plates of the invention have improved characteristics; they have excellent adhesion of the resist in image areas, and ink repellency in non-image areas. The developed printing plates have excellent durability without baking.

Abstract: Printing plates having a photoresist layer thereon that can be exposed by a computer controller laser have improved sensitivity and do not require a photomask step. We have found photoresists that include a film forming polymer, an organo azide and a photosensitive dye that absorbs light at the frequency of the patterning laser and converts it to heat energy. The heat energy in turn elevates the temperature of the organo azide above its dissociation temperature, destroying the azide in areas exposed to the light source, and solubilizing those regions. A post pattern exposure flood exposure with ultraviolet light hardens the unexposed resist, improving its resistance to etch solvents.

Abstract: Printing plates having a photoresist layer thereon that can be exposed by a computer controller laser have improved sensitivity and do not require a photomask step. We have found photoresists that include a film forming polymer, an organo azide and a photosensitive dye that absorbs light at the frequency of the patterning laser and converts it to heat energy. The heat energy in turn elevates the temperature of the organo azide above its dissociation temperature, destroying the azide in areas exposed to the light source, and solubilizing those regions.Flood exposure with ultraviolet light hardens the resist and can be performed prior to or after pattern exposure.

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: 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: Electrodeposition of chromium of selectively constituted crystalline character and grain texture on metal substrates, such as aluminum or steel base lithographic sheet to provide improved and directly chromium plated aluminum or steel base lithographic sheet capable of operatively functioning as a surface plate after exposure of an applied photo sensitive coating thereon.

Abstract: A continuous-tone image, which can be in full color, is scanned to produce color-separation images in halftone dots. Edges of features in the scanned image are sensed, and the positions and shapes of the halftone dots that define corresponding edges in the halftone reproductions are adjusted so that they conform better to the feature edges. This reduces or eliminates the apparent serrations or roughness of feature edges in the halftone reproductions otherwise caused by misalignment of the halftone dots with the feature edges and improves image definition.

Abstract: A continuous-tone image, which can be in full color, is scanned to produce color-separation images in halftone dots. Edges of features in the scanned image are sensed, and the positions and shapes of the halftone dots that define corresponding edges in the halftone reproductions are adjusted so that they conform better to the feature edges. This reduces or eliminates the apparent serrations or roughness of feature edges in the halftone reproductions otherwise caused by misalignment of the halftone dots with the feature edges and improves image definition.

Abstract: A composite developer-etch composition for chromium-plated lithographic printing plates comprises an aqueous solution of aluminum chloride, a water-soluble chloride other than aluminum chloride, phosphoric acid, and an acid-stable water-soluble reducing agent; the composition having a particular specific gravity range.

Abstract: A composite developer-etch composition for chromium-plated lithographic printing plates comprises an aqueous solution of aluminum chloride, a water-soluble chloride other than aluminum chloride, phosphoric acid, and an acid-stable water-soluble reducing agent; the composition having a particular specific gravity range.

Abstract: A continuous-tone image, which can be in full color, is scanned to produce color-separation images in halftone dots. Edges of features in the scanned image are sensed, and the positions and shapes of the halftone dots that define corresponding edges in the halftone reproductions are adjusted so that they conform better to the feature edges. This reduces or eliminates the apparent serrations or roughness of feature edges in the halftone reproductions otherwise caused by misalignment of the halftone dots with the feature edges and improves image definition. A selection of a screen angle is made from a plurality of screen angles.

Abstract: An inexpensive, strong, durable noncracking, high fidelity lithographic printing plate comprises a soft temper aluminum sheet laminated to a nonstainless steel sheet with an adhesive. If desired, the aluminum sheet can be plated with either copper or chromium and the copper in turn can be plated with chromium.