A process for imaging a lithographic printing plate having a coating containing diazo resins. An ink jet printer is used to apply micro drops of a basic chemical solution that insolubilizes the affected areas of the coating to a developing solution. The latent image may be cured by heating the plate for a short period, and is then developed. The process works with conventional, commercially available lithographic plates and developers.
A method for preparing a lithographic printing plate by means of ink jet printing is disclosed. The ink jet fluid contains an oleophilizing compound having in its chemical structure a phosphorous containing group capable of reacting with the surface of a lithographic receiver.
The present invention concerns an original method of copying a printing plate. Said plate, intended for wet offset printing, comprises a base substrate and a photosensitive layer which is soluble in a solvent.As is conventional, said method comprises selectively eliminating said photosensitive layer at suitable locations and is characterized in that said selective elimination comprises: depositing droplets of said solvent at said suitable locations; and rinsing the plate to evacuate the deposited solvent, which by then is charged with the photosensitive layer eliminated from said locations and is inactive.
A method for the preparation of a negative working lithographic printing plate is disclosed. A printing plate precursor comprising a lithographic support and an image forming layer is mounted on a printing press. A liquid containing a dissolution inhibitor is image-wise dispensed on the precursor by means of ink jet printing. The precursor is developed on press by the application of fountain and ink whereby the image areas are retained and the non-image areas are removed.
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.
A process for imaging a lithographic printing plate having a coating containing diazo resins. An ink jet printer is used to apply micro drops of a basic chemical solution that insolubilizes the affected areas of the coating to a developing solution. The latent image may be cured by heating the plate for a short period, and is then developed. The process works with conventional, commercially available lithographic plates and developers.
