Abstract:
A backside coating is applied to lithographic printing plate precursors and this coating provides sufficient protection so that adjacent precursors are not scratched or otherwise damaged when stacked. The backside coating is readily dissolved during processing or development at a pH of at least 6.5 after the precursors are imaged.
Abstract:
Negative-working imageable elements such as lithographic printing plate precursors, include a free-radically polymerizable component, an initiator composition that is capable of generating free radicals sufficient to initiate polymerization of the free-radically polymerizable component upon exposure to imaging radiation in the presence of a radiation absorbing compound, a radiation absorbing compound, an aerobic free radical inhibitor, optionally a polymeric binder that is not a free radically polymerizable component, and an anaerobic free radical inhibitor. The molar ratio of the anaerobic free radical inhibitor to the aerobic free radical inhibitor is at least 1 :1. This combination of inhibitors provides increased shelf life and good latent image stability particularly when the element includes a polymeric topcoat layer that functions as an oxygen barrier.
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:
Provided is a lithographic printing plate comprising a support substrate having disposed thereon an ablative-absorbing layer and, optionally, a durable, ink-accepting surface layer that is not ablative-absorbing. The ablative-absorbing layer contains a high weight per cent of an organic sulfonic acid component. The printing plate may further comprise a hydrophilic polymeric layer interposed between the ablative-absorbing layer and the substrate. The printing plate may also comprise a primer layer underlying the ablative-absorbing layer with an adhesion-promoting agent present in the primer layer. Also provided are methods of preparing such lithographic printing plates, and methods of preparing imaged lithographic printing plates from such lithographic printing plates by imagewise exposure to a laser and a subsequent cleaning step with water or with a cleaning solution.
Abstract:
A lithographic printing plate precursor is disclosed including on a support a coating comprising (i) a photopolymerisable layer including a polymerisable compound, a first infrared absorbing dye including at least one electron withdrawing substituent and a photoinitiator; and (ii) a top layer provided above the photopolymerisable layer which includes a second infrared absorbing compound which includes a thermocleavable group which transforms into a group which is a stronger electron-donor upon exposure to heat and/or IR radiation, and is capable of forming a print-out image upon exposure to heat and/or IR radiation.
Abstract:
A polymerizable composition contains a binder polymer containing a functional group having a dipole moment of 3.8 debye or more and being represented by the formula (1), (2), (3), (4) or (5) as defined herein, a radical polymerizable compound and a radical polymerization initiator.