Abstract: An aqueous developer for lithographic printing plates and a method for developing the printing plates are disclosed. The developer comprises an organic dispersing agent. The developer develops multi-layer printing plates quickly, with high throughput, but with no sludge formation in the developing process.

Abstract: Positive-working imageable elements and methods for their preparation are disclosed. The elements comprise a hydrophilic substrate; a bottom layer, which contains a positive-working photosensitive composition; and a protective overlayer, which has an overlayer material that reduces the solubility of the photosensitive composition in an aqueous alkaline developer. The overlayer may be conveniently applied by a dip and rinse procedure.

Abstract: A process for making thermally imageable negative working compositions comprising the steps of: (1) providing a patterning composition layer on a substrate, said patterning composition comprising: (a) at least one thermal-generator acid generator, (b) at least one cross-linking resin or compound; (c) at least one binder resin comprising a polymer containing at least one reactive pendent group selected from the group, consisting of hydroxyl, carboxylic acid, sulfonamide, alkoxymethylamide and mixtures thereof; and (d) at least one infrared absorber; (2) subjecting the patterning composition layer to a two-stage radiation exposure; (a) one stage being a flood UV-exposure; and (b) the other stage being a imagewise infrared exposure stage; (3) treating the exposed patterning composition with heat energy; and (4) developing the heat treated, exposed patterning composition with an aqueous alkaline developer to remove the non-imaged areas of the patterning composition and leaving the imaged areas substanti

Abstract: A process for making thermally imageable negative working compositions comprising the steps of:

Abstract: Imageable elements useful in lithographic printing, and processes for their use, are disclosed. The elements comprise a hydrophilic substrate, an imageable layer over the substrate, and a thermally activated crosslinking agent. The imageable layer comprises a polymeric material that comprises one or more functional groups selected from the group consisting of carboxyl, carboxylic acid anhydride, phenolic hydroxyl, and sulphonamide. A preferred crosslinking group is the oxazoline group. The element is heated after exposure and development to crosslink a polymeric material.

Abstract: A method for developing exposed lithographic printing plate precursors using a developer and replenisher is disclosed. The replenisher contains a higher concentration of a coating attack-suppressing agent than the developer, so that the aggressiveness of the developer remains substantially constant during the developer loading cycle.

Abstract: A thermally imageable element, useful as a lithographic printing plate precursor is disclosed. The element comprises a hydrophilic substrate; an underlayer comprising a first polymeric material; and an ink-receptive top layer comprising a second polymeric material and a solubility-suppressing component. The solubility-suppressing component may be a separate dissolution inhibitor compound and/or the second polymeric material may also function as a solubility-suppressing component. On thermal exposure the exposed regions of the top layer becomes more readily soluble in an aqueous developer, allowing the developer to remove the top layer and reveal the surface of the hydrophilic substrate. The lithographic printing plate thus formed has excellent properties, including the absence of sludging of the developer.

Abstract: Multilayer photoimageable elements, useful for forming lithographic printing members, are disclosed. The elements comprise a support, a top layer, and a chemical resistant underlayer. The underlayer is resistant to aggressive washes, such as a UV wash. In one embodiment, the underlayer comprises a copolymer of N-substituted maleimide, methacrylamide, and methacrylic acid. A process for preparing a lithographic printing member is also disclosed.

Abstract: A method for developing exposed lithographic printing plate precursors using a developer and replenisher is disclosed. The replenisher contains a higher concentration of a coating attack-suppressing agent than the developer, so that the aggressiveness of the developer remains substantially constant during the developer loading cycle.

Abstract: Positive-working imageable elements and methods for their preparation are disclosed. The elements comprise a hydrophilic substrate; a bottom layer, which contains a positive-working photosensitive composition; and a protective overlayer, which has an overlayer material that reduces the solubility of the photosensitive composition in an aqueous alkaline developer. The overlayer may be conveniently applied by a dip and rinse procedure.

Abstract: A radiation-sensitive composition comprises: (i) at least one component capable of absorbing IR radiation; and (ii) a diazonium polycondensation product soluble in an organic solvent; with the proviso that the composition does not contain components capable of reacting with decomposition products produced from IR radiation exposure of the diazonium polycondensation product. The composition may additionally comprise a polymeric binder of the type useful for conventional negative-working printing plates. The composition is suitable for preparing thermally imageable printing plate precursors and printing plates and may also be used in a method for providing an image on such plate precursors and printing plates.

Abstract: A heat-sensitive composition, for example a coating on a lithographic printing plate, comprises a carboxylic acid derivative of a cellulosic polymer. The composition may contain a radiation absorbing compound and suitable electromagnetic radiation, preferably infra-red radiation, may be used to heat the composition imagewise. The presence of the cellulosic polymer enhances resistance to certain organic liquids.

Abstract: A thermally imageable element, useful as a lithographic printing plate precursor is disclosed. The element comprises a hydrophilic substrate; an underlayer comprising a first polymeric material; and an ink-receptive top layer comprising a second polymeric material. Preferably, the top layer comprises a compound that functions as a solubility-suppressing component. The solubility-suppressing component may be a separate dissolution inhibitor compound and/or the second polymeric material may also function as a solubility-suppressing component. On thermal exposure the exposed regions of the top layer becomes more readily soluble in an aqueous developer, allowing the developer to remove the top layer and reveal the surface of the hydrophilic substrate. The lithographic printing plate thus formed has excellent properties, including the absence of sludging of the developer.

Abstract: A thermal lithographic printing plate, which can be imaged by thermal energy typically by imagewise exposure with an infrared emitting laser, a thermal printing head, etc., is made up of a hydrophilic substrate, and a composite layer structure composed of two layer coatings. Preferably, the first layer of the composite is composed of an aqueous developable polymer mixture containing a photothermal conversion material which is contiguous to the hydrophilic substrate. The second layer of the composite is composed of one or more non-aqueous soluble polymers which are soluble or dispersible in a solvent which does not dissolve the first layer. The plate is exposed with an infrared laser or a thermal print head, and upon aqueous development of the imaged plate, the exposed portions are removed exposing hydrophilic substrate surfaces receptive to conventional aqueous fountain solutions. The unexposed portions contain the ink-receptive image areas.

Abstract: A thermal lithographic printing plate, which can be imaged by thermal energy typically by imagewise exposure with an infrared emitting laser, a thermal printing head, etc., is made up of a hydrophilic substrate, and a composite layer structure composed of two layer coatings. Preferably, the first layer of the composite is composed of an aqueous developable polymer mixture containing a solubility inhibiting material and a photothermal conversion material which is contiguous to the hydrophilic substrate. The second layer of the composite is insoluble in the aqueous solution, is ink receptive, and is composed of one or more non-aqueous soluble polymers which are soluble or dispersible in a solvent which does not dissolve the first layer. The plate is exposed with an infrared laser or a thermal print head, and upon aqueous development of the imaged plate, the exposed portions are removed exposing hydrophilic substrate surfaces receptive to conventional aqueous fountain solutions.

Abstract: The invention relates to photosensitive compositions containing an alkali-insoluble binder, which i.a. are excellently suitable for preparing thermally developable printing plates.

Abstract: A heat-sensitive composition, for example a coating on a lithographic printing plate, comprises a carboxylic acid derivative of a cellulosic polymer. The composition may contain a radiation absorbing compound and suitable electromagnetic radiation, preferably infra-red radiation, may be used to heat the composition imagewise. The presence of the cellulosic polymer enhances resistance to certain organic liquids.

Abstract: Multilayer photoimageable elements, useful for forming lithographic printing members, are disclosed. The elements comprise a support, a top layer, and a chemical resistant underlayer. The underlayer is resistant to aggressive washes, such as a UV wash. In one embodiment, the underlayer comprises a copolymer of N-substituted maleimide, methacrylamide, and methacrylic acid. A process for preparing a lithographic printing member is also disclosed.

Abstract: The present invention relates to IR-sensitive compositions containing an initiator system comprising: (a) at least one compound capable of absorbing IR light (b) at least one compound capable of producing radicals and (c) at least one polycarboxylic acid comprising an aromatic moiety substituted with a heteroatom selected from N, O and S and also at least two carboxyl groups wherein at least one of the carboxyl groups is bonded to the heteroatom via a methylene group. These compositions are inter alia extraordinarily suitable for the manufacture of printing plates.

Abstract: This invention relates to polyvinyl acetals containing the units A, B, C and D, whereinA is present in an amount of 0.5 to 20 wt.-% and is of the formula ##STR1## B is present in an amount of 15 to 35 wt.-% and is of the formula ##STR2## C is present in an amount of 10 to 50 wt.-% and is of the formula ##STR3## wherein R.sup.1 is an alkyl group with up to 4 carbons, which is optionally substituted by an acid group, or a phenyl group, to which an acid group is attached, wherein the phenyl group optionally comprises 1 to 2 further substituents selected from halos, amino, methoxy, ethoxy, methyl and ethyl groups, or is a group X--NR.sup.6 --CO--Y--COOH, wherein X is an aliphatic, aromatic or araliphatic spacer group, R.sup.6 is hydrogen or an aliphatic, aromatic or araliphatic moiety and Y is a saturated or unsaturated chain- or ring-shaped spacer group, and this unit C may be contained several times with various moieties R.sup.1 independent of one another, and D is present in an amount of 25 to 70 wt.