Abstract: A base plate adapted to be coated with a light-sensitive diazo resin, and a lithographic plate which may be prepared therefrom. The base plate includes a substrate comprising a metal support and having a water-wettable, hydrophilic surface. Over the substrate and in direct contact with the surface is a layer comprising an oleophilic ink-receptive organic resin adapted to receive a light-sensitive coating comprising a diazo resin sensitizer. The oleophilic resin layer is permeable to the sensitizer so that it may penetrate substantially through the resin layer to establish sufficient contiguity between the diazo resin and the substrate so that both the light-sensitive coating and the organic resin layer become anchored to the substrate in the areas of exposure when the light-sensitive coating is exposed to light. Methods of preparing the base plate and lithographic plate are also disclosed.

Abstract: Presensitized lithographic plates having a diazo layer are prepared such that they exhibit a photospeed rendering them suitable for ultra high speed operations including use within laser platemaking systems. These ultra high speed plates have a diazo layer that is exceedingly thin while still being generally uniformly distributed throughout the plate area. The process includes extracting a significant quantity of diazonuim compound or diazonium resin from a diazo layer on a presensitized plate substrate. Plates thus formed are useful in laser exposures for facsimile transmissions, as projection plates, as camera back plates, for step and repeat plate work, and where low intensity light sources are used in conjuction with very large plates.

Abstract: A stabilizer, applied either as a coating over the sub-base layer of a presensitized planographic plate or blended into the sensitizer layer thereof, prevents degradation of the sensitizer enabling such plates to be stored over prolonged periods of time without loss of image quality or printing performance. The stabilizer is an aryl sulfonic acid or derivative thereof and, preferably, a haloaryl sulfonic acid or alkali metal salt thereof. In a particularly preferred presensitized plate, a p-chlorobenzene sulfonic acid coating is directly applied to a silicated anodized aluminum plate base and forms a separate layer interposed between the silicate sub-base and a water soluble diazo resin sensitizer layer.

Abstract: The printing plate processing machine includes a first conveyor for receiving printing plates and a second conveyor for receiving plate-separating sheets, and a feed mechanism for selectively transporting the plates and sheets from a loading station in which the plates and sheets are alternately disposed in a stack, toward the first and second conveyors. A plate and sheet diverting mechanism is located between the first and second conveyors for alternately delivering the plates to the first conveyor and the sheets to the second conveyor. The plates are processed after disposition on the first conveyor. A collecting station received the plates and sheets from the first and second conveyors alternately in a stack after processing of the plates. The feed-mechanism includes a fluid-operated cylinder and ram, the ram being movable selectively between an extended position and a retracted position.