Abstract: An IR-sensitive composition comprising, in addition to a polymeric binder, a free radical polymerizable system consisting of at least one member selected from unsaturated free radical polymerizable monomers, oligomers which are free radical polymerizable, and polymers containing C═C bonds in the back bone and/or in the side chain groups and an initiator system, wherein the initiator system comprises the following components: (a) at least one material capable of absorbing IR radiation, (b) at least one compound capable of producing radicals and (c) at least one hereto-substituted arylacetic acid co-initiator compound indicated by the following general structures: 1

Abstract: A method of processing imageable elements useful as alkaline-developable lithographic printing plate precursors that does not require either a rinsing step or a further gumming step is disclosed. The method comprises simultaneously developing and gumming the imaged element with an aqueous alkaline developing-gumming solution comprising one or more water-soluble polyhydroxy compounds of the following structure: R1(CHOH)nR2 in which n is 4 to 7; and either (i) R1 is hydrogen, aryl, or CH2OH; and R2 is hydrogen, alkyl group having 1 to 4 carbon atoms, CH2OR3 in which R3 is hydrogen or an alkyl group having 1 to 4 carbon atoms, CH2N(R4R5) in which R4 and R5 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, or CO2H, or (ii) R1 and R2 together form a carbon—carbon single bond.

Abstract: A lithographic printing plate precursor comprises a substrate, a free radical polymerizable photosensitive layer comprising a light-sensitive composition on the substrate, and a water-soluble overcoat layer on the photosensitive layer, wherein the overcoat layer comprises polyvinyl alcohol, and a further component that is not amphoteric and is poly(1-vinylimidazole) or a copolymer of 1-vinylimidazole and at least one further monomer. The photosensitive layer comprises a free radical polymerizable component and a photoinitiator.

Abstract: A method and an apparatus for the refreshment and reuse of loaded developers used in lithographic printing are disclosed. The pH of an aqueous, essentially silicate-free loaded developer is reduced to below about 11. Insoluble material is separated, and the pH increased to about 12.0 to 14.0 to produce a refreshed developer. The refreshed developer may be used to develop additional exposed printing plate precursors.

Abstract: An aqueous alkaline developing system for alkaline-developable lithographic printing plates and a method for its use are disclosed. The developing system comprises one or more water-soluble suppressors of the following structure: R1(CHOH)nR2 in which: n is 4 to 7; and either (i) R1 is hydrogen, aryl, or CH2OH; and R2 is alkyl group having 1 to 4 carbon atoms, CH2OR3 in which R3 is an alkyl group having 1 to 4 carbon atoms, CH2N(R4R5) in which R4 and R5 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, or CO2H; or (ii) R1 and R2 together form a carbon—carbon single bond. The developing system is especially suited for developing imageable elements useful as lithographic printing plates. The developing system is especially suited for use with elements in which (1) the imageable layer comprises at least one phenolic resin or at least one polymeric compound having pendent sulfonamide groups, and (2) the substrate is aluminum or and an aluminum alloy.

Abstract: The present invention relates to a light-sensitive composition containing: (i) at least one diazonium polycondensation product or at least one system that can be radically polymerized and consists of photoinitiators and unsaturated compounds which can be radically polymerized or at least one hybrid system consisting of a diazonium polycondensation product and a system that can be radically polymerized and consists of photo initiators and unsaturated compounds which can be radically polymerized, (ii) at least one binding agent and optionally one or more exposure indicators, one or more dyes for increasing the image contrast and one or more acids for stabilizing the light-sensitive composition which is characterized in that the binding agent essentially consists of units (A, B, C, D), whereby A corresponds to formula (I), B corresponds to formula (II), C corresponds to formula (III) and D corresponds to formula (IV). The invention also relates to the use thereof for coating printing plates.

Abstract: The present invention relates to IR-sensitive compositions suitable for the manufacture of printing plates developable on-press. The IR-sensitive compositions comprise a first polymeric binder which does not comprise acidic groups having a pKa value≦8; a second polymeric binder comprising polyether groups; an initiator system; and a free radical polymerizable system comprising at least one member selected from unsaturated free radical polymerizable monomers, free radical polymerizable oligomers and polymers containing C═C bonds in the back bone and/or in the side chain groups. The initiator system includes (i) at least one compound capable of absorbing IR radiation; (ii) at least one compound capable of producing radicals selected from polyhaloalkyl-substituted compounds; and (iii) at least one polycarboxylic acid of formula R4—(CR5R6)r—Y—CH2COOH, wherein oxi<redii+1.

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 copolymer useful in radiation sensitive compositions for lithographic printing plates comprises the units A, B, C and D, wherein A is present in an amount of 0.5 to 30 wt.-% and is of the formula wherein R is hydrogen, C1-C4 alkyl, —CH═COOH or B is present in an amount of 5 to 35 wt.-% and is of the formula C is present in an amount of 10 to 55 wt.

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

Abstract: An aqueous alkaline developing system for alkaline-developable lithographic printing plates and a method for its use are disclosed.

Abstract: A replenisher composition developing exposed radiation-sensitive printing plate precursors for plate/developer systems in which the electrical conductivity of the developer does not decrease to the same extend as the activity of the developer decreases or even increases is disclosed. A method for developing exposed radiation-sensitive printing plates using the replenisher composition is also disclosed.

Abstract: A method for the refreshment and reuse of loaded developers used in lithographic printing is disclosed. A polyoxyalkylene derivative is added to a silicate-containing loaded developer. Insoluble material is separated and the alkalinity level of the resulting essentially colorless liquid adjusted to produce a refreshed developer. The refreshed developer may be used to develop additional exposed imageable elements.

Abstract: A replenisher composition developing exposed radiation-sensitive printing plate precursors for plate/developer systems in which the electrical conductivity of the developer does not decrease to the same extend as the activity of the developer decreases or even increases is disclosed. A method for developing exposed radiation-sensitive printing plates using the replenisher composition is also disclosed.

Abstract: An aqueous alkaline developing system for alkaline-developable lithographic printing plates and a method for its use are disclosed. The developing system comprises one or more water-soluble suppressors of the following structure: R1 (CHOH)nR2 in which: n is 4 to 7; and either (i) R1 is hydrogen, aryl, or CH2OH; and R2 is alkyl group having 1 to 4 carbon atoms, CH2OR3 in which R3 is an alkyl group having 1 to 4 carbon atoms, CH2N(R4R5) in which R4 and R5 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, or CO2H; or (ii) R1 and R2 together form a carbon-carbon single bond. The developing system is especially suited for developing imageable elements useful as lithographic printing plates. The developing system is especially suited for use with elements in which (1) the imageable layer comprises at least one phenolic resin or at least one polymeric compound having pendent sulfonamide groups, and (2) the substrate is aluminum or and an aluminum alloy.

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: An aqueous alkaline developing system for alkaline-developable lithographic printing plates and a method for its use are disclosed.

Abstract: A method of processing imageable elements useful as alkaline-developable lithographic printing plate precursors that does not require either a rinsing step or a further gumming step is disclosed.

Abstract: The present invention relates to IR-sensitive compositions containing an initator system comprising:

Abstract: The use of certain mercapto compounds as shelf life improvers for infrared-sensitive lithographic printing plate precursors is disclosed. The compounds are five-membered heteroaromatic rings containing a nitrogen atom and at least one other heteroatom, which can be oxygen, sulfur, or another nitrogen atom, such that two ring heteroatoms are bonded to a ring carbon bearing a thiol group.