Abstract:
A negative-working heat-sensitive material for making a lithographic printing plate by direct-to-plate recording is disclosed which comprises in the order given a lithographic base having a hydrophilic surface, an oleophilic imaging layer and a cross-linked hydrophilic upper layer, characterize in that the oleophilic imaging layer comprises at least one transition metal complex of an organic acid. Materials according to the invention are characterized by an increased run length and can be used as a printing plate immediately after exposure.
Abstract:
A lithographic printing plate precursor is disclosed which comprises (i) a support having a hydrophilic surface or which is provided with a hydrophilic layer and (ii) a coating provided thereon, the coating comprising an oleophilic layer which, upon image-wise exposure to heat or infrared light and subsequent immersion in an aqueous alkaline developer, dissolves in the developer at a higher dissolution rate in exposed areas than in unexposed areas, wherein the oleophilic layer comprises a polymer that is soluble in the developer and an organic dye in a amount sufficient to provide a visible color to the coating, characterized in that said organic dye does not reduce the dissolution rate of the unexposed areas in the developer. By using non-inhibiting dyes, the sensitivity of the precursor upon image-wise exposure is increased.
Abstract:
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 boron containing group capable of reacting with the surface of a lithographic receiver.
Abstract:
A lithographic printing method is disclosed which comprising the steps of providing an imaging material which comprises a support and an image-recording layer that is not removable with a single-fluid ink which comprises an ink phase and a polar phase; image-wise exposure of the image-recording layer to heat or light without substantially ablating said image-recording layer, thereby switching the affinity of the image-recording towards ink or an ink-abhesive fluid and thereby creating a printing master comprising a lithographic image which consists of unexposed areas that have affinity for one phase of said ink phase and polar phase and of exposed areas that have affinity for the other phase of said ink phase and polar phase; printing, wherein the single-fluid ink is supplied to the printing master. The exposed image-recording layer, which normally exhibits a poor differentiation of hydrophilicity or oleophilicity between exposed and non-exposed areas, provides high quality printed copies in combination with the single-fluid ink.
Abstract:
A negative-working heat-sensitive material for making a lithographic printing plate by direct-to-plate recording is disclosed. The material comprises in the order given a lithographic base having a hydrophilic surface, an oleophilic imaging layer and a cross-linked hydrophilic upper layer which comprises an organic compound derived from sulfonic acid, sulfuric acid, phosphoric acid or phosphonic acid. Materials according to the invention are characterized by an increased water-acceptance in the non-printing areas, which allows a rapid start-up of the press.
Abstract:
A positive working printing plate precursor is disclosed which comprises a hydrophilic support and a coating provided thereon which comprises in the order given a first layer containing an oleophilic resin soluble in an aqueous alkaline developer and a second layer comprising a water repellent-compound. Furthermore, the coating comprises an infrared absorbing dye containing a perfluoroalkyl group providing a printing plate precursor with high sensitivity.
Abstract:
A heat-sensitive lithographic printing plate precursor is disclosed which comprises a hydrophilic support and a coating provided thereon, wherein the coating comprises an infrared light absorbing cyanine dye, the dye containing a bridged methine chain and from three to five groups which are anionic or which become anionic in an aqueous alkaline solution having a pH of at least 9. Such dyes provide high sensitivity and low dye stain after processing.
Abstract:
A method is disclosed for removing ink-accepting areas from a printing master by laser ablation, characterized in that the printing master comprises a substrate which comprises a support and a base layer, wherein the base layer contains a crosslinked hydrophilic binder and a metal oxide. The base layer prevents deterioration of the quality of the substrate due to the laser ablation. In a preferred embodiment, the same substrate is used in a number of consecutive printing cycles of on-press coating, on-press exposure, printing and cleaning.
Abstract:
A positive working printing plate precursor is disclosed which comprises a hydrophilic support and a coating provided thereon which comprises in the order given a first layer containing an oleophilic resin soluble in an aqueous alkaline developer and a second layer comprising a water repellent-compound. Furthermore, the coating comprises an infrared absorbing dye containing a polysiloxane group providing a printing plate precursor with high sensitivity.
Abstract:
A heat-sensitive lithographic printing plate precursor is disclosed comprising a polymer which is soluble in an aqueous alkaline solution and which comprises at least one chromophoric moiety having a light absorption maximum in the wavelength range between 400 and 780 nm. Such materials show no dye stain after processing in areas where the coating has been removed by an alkaline developer.