IR-sensitive lithographic printing plate precursors provide a stable print-out image using a unique IR radiation-sensitive composition in an infrared radiation-sensitive image-recording layer. This IR radiation-sensitive composition includes: (1) a free radical initiator composition that comprises an electron-donating agent; (2) a free radically polymerizable composition; and (3) a color-changing compound that is represented by the Structure (I) having a conjugated carbon chain between the aromatic terminal groups. The compound also has a —SO.sub.2—R.sup.3 group wherein R.sup.3 represents alkyl, aryl or heteroaryl groups. After IR imaging, these precursors exhibit desirable printout images both fresh and after dark storage. The precursors can be developed off-press or on-press.

A method of reproducing a continuous-tone image with a printing press comprises the step of making a printing plate having a halftone raster image comprising regularly tiled halftone cells which consist of a grid of image pixels and non-image pixels; the halftone cells are obtained by digital halftoning with a single threshold array and at least a portion of the halftone cells in the raster image comprise multiple image clusters, image clusters being defined as mutually separated groups of more than 4 adjacent image pixels; the image clusters allow to obtain a printed image of the same image density with less ink than with conventional screens wherein the image pixels are grouped into a single cluster.

A lithographic printing plate precursor is disclosed including a support and a coating including a polymerisable compound, an optionally substituted trihaloalkyl sulfone initiator, a leuco dye and a specific infrared absorbing compound including a six membered ring in the central position.

A lithographic printing plate precursor including an image recording layer on a hydrophilic support, in which the image recording layer includes a polymerization initiator, an infrared absorbent, a polymerizable compound, and an acid color former, and the infrared absorbent includes a compound represented by Formula 1, as well as a method of preparing a lithographic printing plate by use of the lithographic printing plate precursor. In Formula 1, at least one of Ar.sub.1 or Ar.sub.2 has a group represented by —X, where X represents a halogen atom, —C(═O)—X.sub.2—R.sub.11, —C(═O)—NR.sub.12R.sub.13, —O—C(═O)—R.sub.14, —CN, —SO.sub.2N.sub.15R.sub.16, or a perfluoroalkyl group, X.sub.2 represents a single bond or an oxygen atom, R.sub.11 and R.sub.14 each independently represents an alkyl group or an aryl group, and R.sub.12, R.sub.13, R.sub.15 and R.sub.16 each independently represents a hydrogen atom, an alkyl group, or an aryl group: ##STR00001##

Provided is a lithographic printing plate precursor having an aluminum support, an image-recording layer, and a water-soluble overcoat layer in this order, in which the image-recording layer contains an infrared-absorbing polymethine colorant having HOMO of −5.2 eV or less, a polymerization initiator, a polymerizable compound, and a polymer, and the polymer has a constitutional unit formed of an aromatic vinyl compound and a constitutional unit formed of an acrylonitrile compound. Also provided are a method for preparing a lithographic printing plate using the lithographic printing plate precursor.

Provided is a lithographic printing plate precursor having an aluminum support and an image-recording layer on the aluminum support, in which the image-recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and an addition polymerization-type resin having a dispersible group, and in a case where a capacitance Cp of the lithographic printing plate precursor is set to satisfy Cp (t)/Cp (20 seconds)=0.95, t satisfies t<12 seconds or the capacitance Cp of the lithographic printing plate precursor satisfies Cp (0 seconds)>400 nF. Also provided are a method for preparing lithographic printing plate or a lithographic printing method using the lithographic printing plate precursor. The capacitance Cp of the lithographic printing plate precursor is measured by bringing at least a measurement portion of the image-recording layer into contact with a 2% by mass aqueous sodium chloride solution at 25° C.

Provided is an on-machine development type planographic printing plate precursor having a support and an image-recording layer on the support, in which the image-recording layer contains an initiator, an infrared absorber capable of donating electrons to the initiator, and a color-developing substance precursor, the image-recording layer can form an image by exposure to infrared laser, and in a case where the image-recording layer is exposed to an infrared laser with a wavelength of 830 nm at an energy density of 110 mJ/cm.sup.2, a brightness change ΔL of the image-recording layer before and after the exposure is 3.0 or more. Also provided are a method for preparing a planographic printing plate or a planographic printing method in which the on-machine development type planographic printing plate precursor is used.

Provided herein is an imaging blanket for variable data lithography comprising (i) a substrate and (ii) a thermally-conductive composition disposed on the substrate comprising a silicone elastomer and a thermally-conductive filler selected from metal oxides, wherein the thermally-conductive composition has a thermal conductivity ranging from about 0.6 W/m.sup.2 to about 1.6 W/m.sup.2. Further provided herein a method of making the imaging blanket, as well as a printing system comprising the imaging blanket, wherein the imaging blanket has improved thermal conductivity.

Provided herein is an imaging blanket for variable data lithography comprising (i) a substrate and (ii) a thermally-conductive composition disposed on the substrate comprising a silicone elastomer and a thermally-conductive filler selected from metal oxides, wherein the thermally-conductive composition has a thermal conductivity ranging from about 0.6 W/m.sup.2 to about 1.6 W/m.sup.2. Further provided herein a method of making the imaging blanket, as well as a printing system comprising the imaging blanket, wherein the imaging blanket has improved thermal conductivity.

A developer composition for a water-developable photosensitive flexographic printing original plate is disclosed, containing (a) a nonionic surfactant composed of monoalkyl ether and/or monoalkyl ester of polyethylene glycol, wherein a number of carbon atoms of the alkyl group therein is 8 to 19, and wherein an HLB value thereof is 11 to 16; and (b) one or more anionic surfactants selected from the group consisting of oleic acid metal salt, lauric acid metal salt, dodecylbenzene sulfonic acid metal salt and lauryl sulfate metal salt, wherein a content ratio of (a):(b) is 25:75 to 75:25 (mass ratio), and wherein a brushing friction coefficient on a surface of a printing original plate is 0.60 to 0.75[−], when measured in an aqueous developer containing 1% by mass of the developer composition and 99% by mass of water.