Abstract: Negative working thermally imageable elements useful as lithographic printing plate precursors and methods for their use are disclosed. The elements have a substrate, a layer of imageable composition over the substrate, and, optionally, an overcoat layer over the layer of imageable composition. The imageable composition has an allyl-functional polymeric binder. Optimum resolution and on-press performance can be attained without a post-exposure bake. The elements do not require a post-exposure bake and can be used in on-press development applications.

Abstract: The invention comprises a method of preparing an imaged member comprising a substrate having an imagable coating on a face thereof, the method comprising the steps of: (a) imaging a precursor of the member to produce an imaged member which includes image and non-image areas on the coated face; and (b) treating the substrate to increase its dimensional stability, the treatment comprising at least one of: (i) effecting a change in the chemical structure of the substrate, or (ii) coating a non-coated face of the substrate with a fluid, gel, or particulate solid.

Abstract: An imageable element useful as a flexographic printing plate precursor is disclosed. The element is made up of a flexible substrate; a photosensitive layer, which contains a negative working photosensitive composition; an optional barrier layer; and a masking layer. The masking layer is thermally bleachable, comprises a dye that typically has an absorption maximum between about 250 nm and about 600 nm, more typically between about 300 nm and about 500 nm, and is substantially free of photothermal conversion materials.

Abstract: The invention is directed to techniques for compensating for imaging aberrations that result from repeated passes by an imaging laser array. The techniques provide for printing overlapping swaths and providing masking for at least one printing pass. The masks generally expand and contract the breadth of the printing swath.

Abstract: Multi-layer, negative working imageable elements useful as lithographic printing plate precursors are disclosed. The elements contain, in order, a support; an underlayer; and an imageable layer. The imageable layer comprises a negative working imageable composition; and the underlayer is soluble or dispersible in a developer. Elements that can be imaged with ultraviolet or visible radiation and elements that can be imaged with infrared radiation or with heat are disclosed.

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.

Abstract: A method for making a relief printing plate from an imageable lithographic printing plate precursor. The relief printing plate has ink-receptive cured areas, and ink-repellent non-image areas. The method comprises the steps of: a) imaging the lithographic printing plate precursor to produce ink-receptive image areas and ink-repellent non-image areas; b) applying a curable composition to form a coating on ink-receptive image areas; and c) curing the coating to produce ink-receptive cured areas. The method of another embodiment further comprises the steps of: d) applying a curable composition to form a coating on ink-receptive cured areas; e) curing the coating on the cured areas; and f) repeating steps d) and e) to attain a desired relief depth for the ink-receptive cured areas. In the practice of an embodiment of the invention, a modified rotary printing press may be employed to make a relief printing plate from a lithographic printing plate.

Abstract: The present invention provides an imageable composition including an acid curable composition, an acid generator, an infrared absorber having a counter anion derived from a non-volatile acid, and a strong acid such as a sulfonic acid. The imageable composition may include components such as a crosslinkable binder or a colorant. In one embodiment, the imageable composition further includes a colorant having a counter anion derived from a non-volatile acid. The present invention further provides an imageable element, which includes a substrate and an imageable coating on a surface of the substrate. Also provided is method of producing an imaged element according to the invention.

Abstract: A method for producing halftone dot patterns involves generation of a halftone dot pattern one color channel as a function of the halftone dot pattern generated for another color channel. Placement of dots for one color channel in view of dot placement of one or more other color channels can enhance image quality, promoting improved spacing of dots among the halftone dot patterns generated for the overprinted color channels. Dot placement for a color channel may depend on the number of dots placed for color channels that precede it in the halftoning process. With improved dot spacing in view of inter-channel effects, an inter-channel dot placement method can reduce the incidence of mottle and other image artifacts, improving the visual appearance of the integrated image. A master threshold array may be used to produce halftone dot patterns for all color channels, but applied, in effect, on a shifted basis to promote improved inter-channel dot spacing.

Abstract: The present invention relates to IR-sensitive compositions containing an initator system comprising: (a) at least one compound capable of absorbing IR radiation selected from triarylamine dyes, thiazolium dyes, indolium dyes, oxazolium dyes, cyanine dyes, polyaniline dyes, polypyrrole dyes, polythiophene dyes and phthalocyanine pigments (b) at least one compound capable of producing radicals selected from polyhaloalkyl-substituted compounds (c) at least one polycarboxylic acid represented by the following formula I wherein Y is selected from the group consisting of O, S and NR7, each of R4, R5 and R6 is independently selected from the group consisting of hydrogen, C1-C4 alkyl, aryl which is optionally substituted, —COOH and NR8CH2COOH, R7 is selected from the group consisting of hydrogen, C1-C6 alkyl, —CH2CH2OH, and C1-C5 alkyl substituted with -COOH, R8 is selected from the group consisting of —CH2COOH, —CH2OH and —(CH2)2N(CH2COOH)2 and r is 0, 1, 2 or 3 with the proviso that at least one of R4, R5, R

Abstract: The present invention includes an imageable element, which can be: (a) an imageable element comprising an imaging layer which comprises: an aromatic diazonium salt containing compound having an alkoxy substituent and an aromatic diazonium salt containing compound free of an alkoxy substituent; a polyvinyl acetal binder; and a sheet substrate; or (b) an imageable element comprising an imaging layer which comprises: an aromatic diazonium salt containing compound having an alkoxy substituent and an aromatic diazonium salt containing compound free of an alkoxy substituent; and a sheet substrate. The imaging layer includes a total aromatic diazonium salt containing compound content of at least 10 weight percent. The molar ratio of the aromatic diazonium salt containing compound having an alkoxy substituent to the aromatic diazonium salt containing compound that is free of an alkoxy substituent is from about 1.0:1 to 70:1. Upon imagewise exposure and development, an imaged element is obtained.

Abstract: Multi-layer, positive working, thermally sensitive imageable elements, useful as lithographic printing plate precursors, are disclosed. The elements comprises a substrate, an underlayer over the substrate, and a top layer over the underlayer. The top layer comprises polymeric material, which is a solvent soluble novolac resin or a derivative thereof. The polymeric material is a (a) novolac that has a weight average molecular weight of at least 10,000, a derivative thereof functionalized with polar groups, or a derivative thereof functionalized with quadruple hydrogen bonding entities; (b) a solvent soluble m-cresol/p-cresol novolac resins that comprises at least 10 mol % p-cresol and has a weight average molecular weight of at least 8,000, a derivative thereof functionalized with polar groups, or a derivative thereof functionalized with quadruple hydrogen bonding entities; or (c) a mixture thereof. The imageable elements have increased scuff resistance and are thus less susceptible to damage during handling.

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: A donor element for proofing having at least a transfer material disposed on a substrate for the preparation of a digital halftone proof having consistent dot density characteristics over time. The donor element includes a transfer material having a donor binder, a cationic infrared absorbing dye, a thermally activated crosslinking agent and a dispersible material The donor element can also include a distinct, intermediate transfer layer disposed between the substrate and the transfer material. The donor element can be used in conjunction with a receptor element to provide a thermal imaging system.

Abstract: Methods of manufacturing multi-layer thermally imageable elements useful as lithographic printing plate precursors are disclosed. The elements comprise a substrate, an underlayer, and an imageable layer. The imageable layer comprises a first polymeric material and o-diazonaphthoquinone containing material. After the underlayer has been coated over the substrate and the imageable layer has been coated over the underlayer, the element is heated to between about 130° C. and about 200° C. for a time sufficient to decrease the sensitivity of the imageable element to the white light.

Abstract: The present invention provides methods of forming and using thermally imageable composite elements which may be developed into lithographic printing plates. More specifically, the present invention provides a method of forming thermally imageable composite elements which provide substantial developer resistance in desired regions, while maintaining white light desensitivity and durability.

Abstract: A method to reduce effluence during or immediately after imaging of a printing plate is described. In one embodiment of the invention, the method comprises: (a) applying to a substrate a coating composition comprising a photothermal converter and at least one polymer comprising thiosulfate groups to obtain a coating; and (b) applying a water soluble topcoat to the coating. Preferably, the water soluble topcoat does not comprise a photothermal converter. In another embodiment of the invention, the method comprises applying to a substrate a composition comprising: (a) a photothermal converter; (b) at least one polymer comprising thiosulfate groups; and (c) an additive selected from the group consisting of diazonium, iodonium, copper(I), alkoxypyridinium or maleimide additives.

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+1.6 eV, where oxi=oxidation potential of component (i) in eV, and redii=reduction potential of component (ii) in eV.

Abstract: A method for reducing start up blinding in no-process lithographic printing plates is disclosed. An imageable element, comprising an imageable layer over a substrate, is thermally imaged. The imageable layer comprises a thermally sensitive polymer that comprises quaternary ammonium salts of carboxylic acids. Following imaging, the surface of the imaged imageable is contacted with an aqueous solution comprising 0.05 wt % to about 5 wt % of an added organic acid having a pKa of about 1 to about 6. This reduces the amount of waste produced by the printing process by reducing the number of unusable sheets produced during the “make ready” process.

Abstract: A method for forming a printing plate from a printing plate precursor having a radiation-sensitive layer, sensitive to radiation in a first frequency spectrum such as the far or near infrared, and to radiation in a second frequency spectrum other than the first frequency spectrum such as visible or ultraviolet. The plate is exposed twice. Once to imaging radiation in the first frequency spectrum and again to radiation in the second frequency spectrum. The second frequency spectrum exposure is done only to the areas of the plate undesirably shaded during the imagewise exposure.