Abstract: In a stack of lithographic printing plate precursors, each plate has an aluminum substrate, a photo-polymerizable (PS) layer carried on the upper surface of the substrate, a water soluble topcoat oxidation inhibitor carried on the PS layer, and a water insoluble bottom coat on the lower surface of the substrate, wherein the bottom coat of each intermediate plate is in direct covering contact with the topcoat of an immediately adjacent plate. The associated process includes cutting through multiple sections of the finished web without interleaving to produce stacks of finally sized precursor plates, and without interleafing, packaging together at least 25 stacked and confronting precursor plates.

Abstract: A method for producing a printable lithographic plate from a negative working, radiation imageable plate having an oleophilic resin coating that reacts to radiation by cross linking and is non-ionically adhered to a hydrophilic substrate. Steps include imagewise radiation exposing the coating to produce an imaged plate having partially reacted image areas including unreacted coating material, and completely unreacted nonimage areas; developing the plate by removing only the unreacted, nonimage areas from the substrate while retaining unreacted material in the image areas; and blanket exposing the developed plate with a source of energy which further reacts the retained unreacted material in the image areas. A plate with a coating containing resin particles can be imaged to produce initial cross-linking, then mechanically developed. Hardening of the imaged areas is completed with a relatively intense post-heating at 160 deg. C., which further cross links the monomer and fuses the resin particles.

Abstract: A method of on-press development of a lithographic printing plate having an imaged photosensitive (PS) coating by (a) applying an emulsive film of press ink and fountain onto the entire PS coating; (b) transferring all nonimage areas of the inked PS coating and all of the ink film on the nonimage areas of the PS coating from the plate to a blanket roll while the image areas of the PS coating remain on the substrate, wherein the nonimage areas are transferred to the blanket roll in particulate form without dissolution or dispersion in any ink or fountain; and (c) contacting the blanket roll with a paper leader to further transfer all the ink, fountain water, and particles of nonimage PS coating that were transferred to the blanket roll, from the blanket roll to the paper leader.

Abstract: A printing plate having a substrate and a radiation sensitive, negative working, organic, polymerizable, photosensitive (PS) resin coating non-ionically adhered to the substrate such that the cohesion of the PS coating exceeds the adhesion of the PS coating to the substrate. The PS coating contains active components that participate in radiation induced polymerization, all of which active components are soluble in non-aqueous solvents and none of which active components are soluble or dispersible in any of the group of fluids consisting of water, fountain solution, ink, and press ink. The PS coating has sufficient cohesion and surface tack to adhere to and be mechanically pulled off the substrate by press ink as particulates without dissolution or dispersion into the press ink.

Abstract: A plate carries a solvent-soluble, radiation-polymerizable, oleophilic resin coating non-ionically adhered on a hydrophilic substrate, which can be imagewise exposed to polymerizing radiation and then directly processed by the application of disruptive mechanical forces such as compression or tension to remove the unimaged areas as undissolved particles, using pressurized water and brushing pre-press, or the tack of the ink on-press.

Abstract: A method for preparing lithographic printing plates for on-press development, including sequentially feeding the plates to an imaging station to produce a plurality of latent image reference marks allocated among at least two margins along a respective two sides of the plate, and a latent print image within the margins. The imaged plates are transported from the imaging station to a plate bending station where the short ends of the plate are bent over. Between the imaging station and the bending station, the unimaged areas of the coating in at least two of the margins are removed to reveal the reference marks without developing the latent print image. Preferably, the reference marks are revealed while the plate is temporarily aligned in landscape orientation at stop, such as at the feeder to the bending station.

Abstract: On-press development of an imaged printing plate on a plate cylinder, in which ink is applied by an ink form roll, a blanket roll is in contact with the plate, a rubber roll is opposed to the blanket roll, and printable media passes between the blanket roll and the rubber roll. The plate comprises a substrate carrying an imaged coating and nonimage areas. The respective cohesive and adhesive properties of the nonimage and image areas to the applied ink, substrate, blanket roll and printable medium, and the ink to the roll are such that the blanket roll pulls the ink from the plate and the ink pulls the nonimage areas from the substrate as undissolved particles that are transferred by the blanket with the ink to the printable media.

Abstract: On-press development of an imaged printing plate on a plate cylinder, in which ink is applied by an ink form roll, a blanket roll is in contact with the plate, a rubber roll is opposed to the blanket roll, and printable media passes between the blanket roll and the rubber roll. The plate comprises a substrate carrying an imaged coating, in which nonimage areas have cohesion C1, adhesion to the substrate A1, and adhesion to the applied ink A3 and image areas have cohesion C2, adhesion to the substrate A2, and adhesion to the applied ink A4. The ink has cohesion C3 and adhesion A5 to the blanket roll. The nonimage areas have adhesion A6 to the printable medium and the ink has adhesion A7 to the medium. The adhesions and cohesions are such that the blanket roll pulls the ink from the plate and the ink pulls the nonimage areas from the substrate as undissolved particles that are transferred by the blanket with the ink to the printable media.

Abstract: A solvent-soluble, radiation-polymerizable, oleophilic resin coating non-ionically adhered on a hydrophilic substrate can be imagewise exposed to polymerizing radiation and then directly processed by the application of disruptive mechanical forces such as compression or tension to remove the unimaged areas as undissolved particles, using pressurized water and brushing pre-press, or the tack of the ink on-press.

Abstract: Excellent development of planographic printing plates can be achieved by exposing an imaged, negative working, photopolymerizable coating to a high pressure stream of essentially heated but otherwise untreated tap water, whereby the water completely removes only the less cohesive and adhesive (e.g., partially polymerized) regions to the substrate, thereby directly producing a printing plate having an image pattern of highly cohesive and adhesive, oleophilic regions of the coating and hydrophilic regions of the substrate. The coating removal mechanism appears to be due entirely to ablation. The process variables of spray pressure, spray volumetric flow rate, and water temperature can be traded off to achieve one or more targets for plate quality, energy conservation, production rate, and equipment availability.

Abstract: A novel coating for lithographic printing plates can be imagewise exposed to radiation and then directly processed with only water to remove the non-exposed regions of the coating. The coating comprises a polymer, a monomer and/or oligomer, polymerization or cross link initiator, stabilizer, and dye or pigment, such that after imaging, the non-imaged resin areas are removable from the planar surface by penetration of water through the non-imaged coating without dissolution of the resin components of the coating, to form a lithographic printing plate with clearly defined image and non-image areas. The stabilizer is a solvent soluble, partially water soluble, non-polymerizable organic component that enables the coating to be removable by water in the non-cross linked areas.

Abstract: Excellent development of planographic printing plates can be achieved by exposing an imaged, negative working, photopolymerizable coating to a high pressure stream of essentially untreated tap water, whereby the water completely removes only the less cohesive and adhesive (e.g., partially polymerized) regions to the substrate, thereby directly producing a printing plate having an image pattern of highly cohesive and adhesive, oleophilic regions of the coating and hydrophilic regions of the substrate. The coating removal mechanism appears to be due entirely to ablation. The high pressure stream is preferably delivered to the plate through at least one nozzle having a discharge pressure greater than about 200 psi. Each nozzle preferably has a spray pattern that impinges the plate over a substantially rectangular region of the plate, and the nozzle and plate translate relative to each other.

Abstract: Excellent development of photosensitive coatings on planographic printing plates is achieved by directing a dynamic flow of fresh alkaline developer solution that impinges on a target area of the coating extending the width of the plate and floods the target area with a turbulent flow. At sufficient volumetric flow rate, the developer solution at the target area is constantly displaced during the development time, whereby no boundary layer forms on and travels with the plate during the development time and thus the target area is always in contact with fresh developer solution.

Abstract: An imaged plate processor for covering the imaged coating with a turbulent flow of fresh developer solution for a short dwell time, and which preferably can be modified by the end user for development of a wide range of plates. The processor comprises a flat support surface for the plate, a plate feeder to the support surface, a plate transporter, and a nozzle array oriented to discharge developer solution onto a plate as the plate moves along the support surface. A source of fresh developer solution is connected to a pump for pressurizing the developer in the nozzle array in the range of about 5 to 250 psi, whereby fresh developer solution is directed from the nozzles as a pressurized flow pattern transversely onto the plate. A continual flow of fresh developer solution impinges on successive areas of the plate. Adjustable variables for accommodating a variety of plates include at least one of spray pressure and plate transport speed.

Abstract: A process for developing an imaged lithographic printing plate, including the step of delivering developing fluid to the plate at a high volumetric flow rate for a short dwell time such that the non-image is completely solubilized while the image remains unaffected by the developing fluid. At sufficient volumetric flow rate, the developer solution at the target area is constantly displaced during the development time, whereby no boundary layer forms on and travels with the plate during the development time and thus the target area is always in contact with fresh developer solution.

Abstract: The invention generally relates to positive-working coating compositions and to a substrate formed with a coating of that composition. Advantageous versions of the invention provide an infrared imageable, positive lithographic printing plate having a coating comprising a hydroxy substituted polymer, a diphenylcarbinol solubility suppressing compound and an infrared radiation absorbing compound.

Abstract: The invention generally relates to positive-working coating compositions and to a substrate formed with a coating of that composition. Advantageous versions of the invention provide an infrared imageable, positive lithographic printing plate having a coating comprising a hydroxy substituted polymer, a diphenylcarbinol solubility suppressing compound and an infrared radiation absorbing compound.

Abstract: The invention relates to the development of lithographic printing plates and comprises the application of a thin film of developer solution to each plate in a controlled manner using a jetting printhead. Sensors and control means activate and deactivate the jetting printhead in response to the presence or absence of a plate. The developer is allowed to dwell on the plate as it is conveyed across a support structure for a sufficient time to allow for percolation into and/or dissolution of the soluble areas of the coating and is then washed off and sent to waste.

Abstract: Disclosed herein are a method and apparatus for efficiently processing workpieces which are developed using a liquid developer. According to the invention a first set of workpieces is obtained from an imaging station, a second set of workpieces is obtained from a workpiece collection device, and the workpieces from the first and second sets are aligned in a contiguous arrangement, with the workpieces from the first set preferably being interspersed with those from the second set. Developer is then applied to the group of contiguous workpleces, thereby reducing the amount of overrun or overspray of developer that would otherwise result from individual processing of workpieces. The invention is particularly well-suited for use in preparing lithographic printing plates.

Abstract: The invention relates to the application of a uniform film of a fluid to the surface of a flat workpiece as it is being conveyed through a workstation. The invention is specifically directed to the development of lithographic printing plates and comprises the application of the thin film of developer solution to each plate in a controlled manner using a wire-wound coating device and a unique manner of metering and feeding fresh fluid to the wire-wound device. Specifically, the fluid is gently fed onto the wire-wound device by simple volumetric displacement and overflow from the inside of a hollow tube onto the wire and the flow is controlled by sensing the beginning and end of each workpiece or plate. The hollow tube may be the wire-wound component or it may be a tube mounted above the wire-wound component. The spent developer is rinsed and sent to waste. According to the invention, only fresh developer solution is applied at a uniform film thickness, thereby achieving uniform image development.