Abstract: A method of processing an on-press developable lithographic printing plate involving the removal of overcoat after imagewise exposure and before on-press development is described. The plate comprises a substrate, an on-press ink and/or fountain solution developable photosensitive layer, and an overcoat. The laser imaged plate is stripped off the overcoat, and then under a white room light mounted on press and developed with ink and/or fountain solution. Here the plate is capable of hardening upon exposure to a laser, has limited white light stability before the removal of the overcoat, and has significantly improved white light stability after the removal of the overcoat.

Abstract: A method of processing an on-press developable lithographic printing plate involving the removal of the overcoat after laser imaging and before on-press development is described. The plate comprises a substrate, an on-press ink and/or fountain solution developable photosensitive layer, and an overcoat. The laser imaged plate is mechanically stripped off the overcoat, and then developed with ink and/or fountain solution on a lithographic press. Such a process allows the use of overcoat to achieve faster photospeed and improved durability of the plate without having various issues as related to overcoat such as contamination to the fountain solution, difficulty to remove of certain overcoat, and limited white light stability.

Abstract: High speed violet or ultraviolet laser sensitive lithographic printing plate comprising on a hydrophilic substrate a specific photosensitive composition is described. The photosensitive layer comprises an alkaline soluble polymeric binder, a multifunctional (meth)acrylate monomer, a free-radical initiator, and a sensitizing dye. The plate is imagewise exposed with a violet or ultraviolet laser at a dosage of less than 300 ?J/cm2, and then developed with an aqueous alkaline developer. Higher monomer to polymer weight ratio is advantageously used. A pigment is preferably incorporated into the photosensitive coating solution as a liquid dispersion. The exposed plate is preferably developed on a processor with an alkaline developer coupled with a replenisher having higher pH.

Abstract: A method of treating a laser exposed lithographic printing plate with a deactivating solution followed by overall irradiation is described. The plate comprises on a substrate a photosensitive layer capable of photo hardening. The deactivating solution is capable of deactivating the photo hardening capability of the photosensitive layer in the non-hardened areas so that the overall irradiation does not cause hardening of the photosensitive layer in the non-hardened areas. The deactivation and overall irradiation cause one or more chemical or physical changes to the photosensitive layer, such as further hardening of the imaged areas, improved contrast, improved developability, or improved substrate hydrophilicity. The overall irradiated plate is further developed on press with ink and/or fountain solution or off press with a developer. For off-press development, the developer may be used as the deactivating solution.

Abstract: Negative lithographic printing plate having on a substrate a photosensitive layer comprising an alkaline soluble polymeric binder, an alkaline insoluble polymeric binder, a polymerizable monomer, and an initiator is described. The photosensitive layer is imagewise exposed with a radiation to cause hardening in the exposed areas, and then developed to remove the non-hardened areas. The combination of both alkaline soluble polymeric binder and alkaline insoluble polymeric hinder in a photosensitive layer can give excellent combined durability, developability, and coatability.

Abstract: High speed violet or ultraviolet laser sensitive lithographic printing plate comprising on a hydrophilic substrate a specific photosensitive composition is described. The photosensitive layer comprises an alkaline soluble polymeric binder, a multifunctional (meth)acrylate monomer, a free-radical initiator, and a sensitizing dye. The plate is imagewise exposed with a violet or ultraviolet laser at a dosage of less than 300 ?J/cm2, and then developed with an aqueous alkaline developer. Higher monomer to polymer weight ratio is advantageously used. A pigment is preferably incorporated into the photosensitive coating solution as a liquid dispersion. The exposed plate is preferably developed on a processor with an alkaline developer coupled with a replenisher having higher pH.

Abstract: A method of processing an on-press developable lithographic printing plate with ink and/or fountain solution is described. The plate comprises on a substrate a photosensitive layer which is either capable of hardening (negative-working) or solubilization (positive-working) upon exposure to a laser, the non-hardened or solubilized areas of the photosensitive layer being soluble or dispersible in ink and/or fountain solution. The plate is exposed with a laser, heated to an elevated temperature, and then developed with ink and/or fountain solution on a lithographic press. The laser exposed plate is preferably heated by passing through a heating device or while mounted on a lithographic press before on-press development.

Abstract: A method of on-press developing a high-speed laser sensitive lithographic printing plate with ink and/or fountain solution is described. The plate comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser. The plate is exposed with a laser and on-press developed with ink and/or fountain solution. At least a portion of the on-press development is performed with the plate under a yellow-red light, in substantial darkness, or under a light that is different from the light for printing and does not cause hardening of the photosensitive layer during on-press development.

Abstract: A method of processing an overcoat-free on-press developable lithographic printing plate with ink and/or fountain solution is described. The plate comprises on a substrate a photosensitive layer which is either capable of hardening (negative-working) or solubilization (positive-working) upon exposure to a laser, the non-hardened or solubilized areas of the photosensitive layer being soluble or dispersible in ink and/or fountain solution. The plate is exposed with a laser, heated to an elevated temperature, and then developed with ink and/or fountain solution on a lithographic press. The laser exposed plate is preferably heated by passing through a heating device or while mounted on a lithographic press before on-press development.

Abstract: A method of deactivating an on-press ink and/or fountain solution developable lithographic printing plate is described. The printing member comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser. The plate is exposed with a laser, deactivated, and then on-press developed with ink and/or fountain solution. The deactivation is carried out by overall applying to the plate a deactivating agent, heat, or a radiation that has different wavelength from the laser and does not cause hardening of the photosensitive layer. The deactivation allows the plate to be handled on press under white light or other light that is unsafe for a non-deactivated plate.

Abstract: A method of forming visible image on an on-press developable lithographic printing plate is described. The plate comprises on a substrate a photosensitive layer developable with ink and/or fountain solution and capable of hardening upon exposure to a radiation. The plate is imagewise exposed with a radiation, overall treated with a discoloring agent to form visible image or enhanced visible image, and then on-press developed with ink and/or fountain solution. The formation of visible image allows easy identification or inspection of the plate by the pressman before mounting on press.

Abstract: A method of treating an on-press developable lithographic printing plate with an aqueous treating solution after imagewise exposure and before on-press development is described. The plate comprises on a substrate a photosensitive layer developable with ink and/or fountain solution and capable of hardening upon exposure to a radiation. The plate is imagewise exposed with a radiation, overall treated with a treating solution to cause at least one chemical or physical change in the photosensitive layer or on the substrate surface, and then on-press developed with ink and/or fountain solution. Such a treatment allows improvement on the performance of the imagewise exposed plate by, for example, improving the white light stability, forming visible imaging, increasing the hydrophilicity of the substrate, or increasing the developability of the photosensitive layer.

Abstract: A lithographic printing press having a plate cylinder in a covered compartment suitable for on-press imaging and developing a laser sensitive plate is described. The plate cylinder as well as certain other press parts is covered by non-transparent and/or safe-light-passing-only covers so that no or only limited amount of unsafe light passes onto the plate mounted on the plate cylinder during on-press imaging and development. The plate comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser having a wavelength selected from 200 to 1200 nm. The plate is on-press exposed with the laser, developed with ink and/or fountain solution, and then directly prints inked images to the receiving sheets.

Abstract: A device as well as method for deactivating without developing an exposed lithographic printing plate is disclosed. The device comprises a structure for providing a deactivating agent that is capable of deactivating without developing the plate. The plate comprises on a substrate a photosensitive layer capable of hardening upon exposure to a radiation, and becoming incapable of or having reduced rate of hardening after contacting with a deactivating agent. The deactivated plate is safe or has better stability at room lighting, and can be handled under room lighting before and during development. The development can be on press with ink and/or fountain solution or off press with a liquid developer.

Abstract: A method of on-press developing a laser sensitive lithographic printing plate with ink and/or fountain solution is described. The printing member comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser. The plate is exposed with a laser and on-press developed with ink and/or fountain solution. The exposure and development are performed with the plate under lightings that contain no or substantially no radiation below a wavelength selected from 400 to 650 nm, or in the dark or substantially dark.

Abstract: A method of on-press developing a laser sensitive lithographic printing plate with ink and/or fountain solution is described. The printing member comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser. The plate is exposed with a laser and on-press developed with ink and/or fountain solution. The exposure and development are performed with the plate under lightings that contain no or substantially no radiation below a wavelength selected from 400 to 650 nm, or in the dark or substantially dark.

Abstract: A method of developing a laser sensitive lithographic printing plate is described. The plate comprises on a substrate a photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to a laser. The plate is exposed with a laser and deactivated under a safe light or in the dark, and then on-press developed with ink and/or fountain solution preferably under white light. Alternatively, the plate is developed off press with ink and/or fountain solution, or with an organic solvent-based or oil-based liquid or paste and/or an aqueous solution, and then mounted on press for lithographic printing.

Abstract: High speed violet or ultraviolet laser sensitive lithographic printing plate comprising on a hydrophilic substrate a specific photosensitive composition is described. The photosensitive layer comprises a polymeric binder, a multifunctional (meth)acrylate monomer, a free-radical initiator, and a sensitizing dye, with specific weight ratio of the monomer to the polymer. Combination of multifunctional urethane (meth)acrylate monomer and multifunctional non-urethane (meth)acrylate monomer can be advantageously used. The plate is imagewise exposed with a violet or ultraviolet laser at a dosage of less than 300 ?J/cm2, and then developed with an aqueous developer or with ink and/or fountain solution.

Abstract: A method of deactivating and on-press developing an exposed lithographic printing plate is disclosed. The plate comprises on a substrate a photosensitive layer developable with ink and/or fountain solution and capable of hardening upon exposure to a radiation. The plate is exposed with the radiation, deactivated, and then on-press developed with ink and/or fountain solution. The deactivation of the exposed plate allows the handling of the plate under regular office light or any other light without causing the hardening of the non-exposed areas of the photosensitive layer.

Abstract: High speed violet or ultraviolet laser sensitive lithographic printing plate comprising on a hydrophilic substrate a specific photosensitive composition is described. The photosensitive layer comprises a polymeric binder, a multifunctional (meth)acrylate monomer, a free-radical initiator, and a sensitizing dye, with specific weight ratio of the monomer to the polymer. Combination of multifunctional urethane (meth)acrylate monomer and multifunctional non-urethane (meth)acrylate monomer can be advantageously used. The plate is imagewise exposed with a violet or ultraviolet laser at a dosage of less than 300 ?J/cm2, and then developed with an aqueous developer or with ink and/or fountain solution.