Abstract: This invention relates to a novel photosensitive element comprising: a support having a surface; a photosensitive layer on the surface; and a transparent, protective coating on the photosensitive layer. The photosensitive layer comprises a composition of an ethylenically unsaturated compound and a photo-initiator, and is capable of photo-initiated addition polymerization. The PVA-based protective coating is substantially impermeable to atmospheric oxygen. In accordance with this invention, it has been discovered that photo-speed in a photosensitive element is substantially enhanced if this coating contains a acid, and especially if the coating exhibits an acidic pH, preferably less than about 5.5. The protective coating preferably also contains a second polymer which imparts surface hardness and scratch resistance to the protective coating. The coating may further contain a plasticizer to impart flexibility and inhibit cracking and snow-flaking.

Abstract: A waste water cleaning system for use with apparatus for processing exposed lithographic plates, the processing apparatus receiving wash water for use in the processing. The cleaning system includes a centrifuge for removing contaminants from waste water from the processing apparatus, the centrifuge having an inlet for receiving waste water from the processing apparatus and an outlet for discharging the cleaned water. The cleaning system also includes means for carrying the waste water from the processing apparatus to the inlet. The cleaning system further includes control means for controlling the operation of the processing apparatus and the centrifuge. The control means includes means for starting the centrifuge and means for starting the flow of wash water into the processing apparatus a first predetermined time after the start of the centrifuge.

Abstract: Apparatus for processing lithographic plates after they have been exposed and developed having a system for feeding plates forward one after another in a predetermined path with the exposed and developed face of the plate facing up, a heating system for heating each plate as it travels along said path, a system for blowing air on each plate to cool it, a system for spraying water on and scrubbing the upper face of each plate for washing it, and a system for delivering preservative onto and rubbing it over the upper face of each plate.

Abstract: A method of increasing the strength, abrasion resistance, solvent resistance, and press life of a lithographic image comprising a layer of light-reacted light sensitive material and an outer layer comprising an epoxy resin overlying the light-reacted layer. In the method, the surface of the outer layer is contacted and wetted with an aqueous solution comprising a least about 7% by weight of a boron trifluoride-amine complex. Solvent is evaporated from the solution on the surface to deposit dry boron trifluoride-amine complex on the outer layer and the outer layer is heated in the presence of the complex to cross-link the epoxy resin and form a hard, tough, abrasion-resistant, solvent-resistant and wear-resistant epoxy resin layer at the outside of the image. Further included in the invention are a curing composition adapted for topical application to a lithographic image in carrying out the method of the invention and a planographic printing plate produced thereby.

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: 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: 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 lighographic plate are also disclosed.

Abstract: Photosensitive homopolymers and substantially non-crosslinked copolymers containing the recurring unit: ##EQU1## R.sub.1 may be substituted or unsubstituted alkylene, aralkylene, alkoxyalkylene or aryloxyalkylene. R.sub.2 is a substituted or unsubstituted aryl group or heterocyclic group having aromatic character. R.sub.3, R.sub.4, and R.sub.5 are hydrogen, halogen or lower alkyl. R.sub.6 and R.sub.7 may be hydrogen, halogen, nitro, lower alkyl, phenyl, substituted phenyl, phenoxy and lower alkoxy. Lithographic plates bearing these photosensitive polymers can be stored without deterioration for extended periods prior to exposure, and produce highly abrasion resistant plates on being exposed. The photosensitive polymers of the invention are preferably produced by homopolymerization of novel monomers having the general formula ##EQU2## where R.sub.1 .sub.' is alkylene, haloalkylene, alkoxyalkylene, aminoalkylene, cycloalkylene, aralkylene, cycloalkylalkylene, cyanoalkylene, and aryloxyalkylene, and R.sub.2, R.