Provided are a lithographic printing plate precursor having an image-recording layer on a hydrophilic support, in which the image-recording layer includes an organic polymer particle, and the organic polymer particle is a reaction product obtained by at least reacting an aromatic polyvalent isocyanate compound having a structure represented by Formula PO and water, a method for making a lithographic printing plate having excellent printing resistance in the case of using an ultraviolet-curable ink in printing, a new organic polymer particle, and a resin composition including the organic polymer particle.

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A method of imaging printing plates uses a single imaging device having at least one laser delivering, in an imagewise manner, pulsed electromagnetic energy of pulse duration not greater than 110.sup.6 seconds. Such an imaging method permits the imaging of a plurality of types of printing plates irrespective of any sensitised imaging chemistry contained in their coatings.

A color-forming composition is useful to provide a printout image in an imaged lithographic printing plate precursor. This color-forming composition includes (a) an acid generator; (b) a tetraaryl borate; (c) an acid-sensitive dye precursor; and (d) a compound having the following Structure (I):

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wherein n is 1, 2, 3, or 4; R independently represents a monovalent substituent or the atoms necessary to form a fused ring if n is at least 2, and at least one R substituent is an electron-withdrawing group. The color-forming composition is included within a negative-working radiation-sensitive imageable layer along with a free radically polymerizable component and a radiation absorber such as an infrared radiation absorber.

Provided are a lithographic printing plate precursor having an image-recording layer on a hydrophilic support, in which the image-recording layer includes a polymer particle including an addition polymerization-type resin having a hydrophilic structure and a crosslinking structure, a method for producing a lithographic printing plate in which the lithographic printing plate precursor is used, a polymer particle including an addition polymerization-type resin having a hydrophilic structure and a crosslinking structure, and a composition including the polymer particle.

The imaging sensitivity of negative-working lithographic printing plate precursors is improved by removing ozone from the ambient air surrounding the precursors that can be stored near an imaging means such as a platesetter prior to use. Ozone can be removed using a suitable filter containing activated charcoal or other ozone decomposing means, through which ambient air is filtered before and during the imaging process.

A photosensitive resin composition contains a polymer compound having a linking group represented by Formula A-1 in the main chain; and an infrared absorbing material. In Formula A-1, R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a monovalent organic group, and X.sup.1 is a specific linking group. ##STR00001##

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 the following Formula 2.

XFormula 2

X represents a halogen atom, C(O)X.sub.2R.sub.11, C(O)NR.sub.12R.sub.13, OC(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 represent an alkyl group or an aryl group, and R.sub.12, R.sub.13, R.sub.15 and R.sub.16 each independently represent a hydrogen atom, an alkyl group, or an aryl group.

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The present invention provides a silicone composition for use in a printing plate, the composition including at least: a SiH group-containing compound; a compound represented by the following general formula (I); a compound represented by the following general formula (II); and/or a compound represented by the following general formula (III); wherein Ds in the compound represented by the general formula (I), Gs in the compound represented by the general formula (II) and Js in the compound represented by the general formula (III) each represents an acetoxy group or a dialkyloximino group: A-Si-(D).sub.3 (I) (wherein in the general formula (I), A represents a non-hydrolyzable functional group capable of undergoing a hydrosilylation reaction with a SiH group); E-Si-(G).sub.3 (II) (wherein in the general formula (II), E represents a non-hydrolyzable functional group incapable of undergoing a hydrosilylation reaction with a SiH group); and Si-(J).sub.4 (III). An object of the present invention is to provide a silicone composition for use in a printing plate, for obtaining a planographic printing plate precursor or a planographic printing plate which includes a silicone rubber layer having an excellent adhesion to an underlying layer despite being a fast-curing silicone rubber layer, and which has an excellent ink repellency and scratch resistance.

A negative type photosensitive resin composition includes a polymer compound which has, in a main chain thereof, a constitutional unit A represented by Formula A-1, a constitutional unit B that is at least one of constitutional units represented by Formulae B-1, B-2, B-3, B-4, B-5, B-6, or B-7, and a constitutional unit C containing an ethylenically unsaturated group; and a polymerization initiator. A negative type planographic printing plate precursor includes an image recording layer containing the negative type photosensitive resin composition. A method of preparing a planographic printing plate includes, in order, an exposure step of image-exposing the negative type planographic printing plate precursor; and a development step of performing development by removing a non-exposed portion of the exposed negative type planographic printing plate precursor using a developer. ##STR00001##

A method for setting up a lithographic printing press is provided which reduces the make-ready time of on-press developable printing plates so that less copies are wasted. The method uses an ink boost at the startup of the press by presetting the inking system to a configuration whereby the amount of ink supplied to the plate is different from the amount prescribed by standard printing conditions. The ink boost can be positive or negative and can be made dependent on the difference in the image coverage between plates used in successive print jobs or on different paper types used in successive print jobs.