A lithographic printing plate precursor is disclosed including a support and a coating comprising (i) a photopolymerisable layer including a polymerisable compound and a photoinitiator, and a toplayer provided above the photopolymerisable layer; characterized in that the toplayer includes an leuco dye and a hydrophobic binder.

A lithographic printing plate precursor is disclosed including a support and a coating comprising (i) a photopolymerisable layer including a polymerisable compound and an optionally substituted trihaloalkyl sulfone photoinitiator, and (ii) a toplayer provided above the photopolymerisable layer; characterized in that the toplayer includes an infrared absorbing dye capable of forming a print-out image upon exposure to heat and/or IR radiation.

The present invention provides a lithographic printing plate precursor including at least a heat-sensitive layer and an ink repellent layer disposed on a substrate, the rate of gas generation therefrom being 6.510.sup.5 g/m.sup.3 to 12.510.sup.5 g/m.sup.3 as determined by GC-MS analysis in which the lithographic printing plate precursor is heated in a nitrogen stream at 450 C. for 5 minutes, and also provides a method for producing a lithographic printing plate and a method for producing printed matter therefrom.

Provided are a color developing composition including a compound represented by Formula 1, a lithographic printing plate precursor having at least a layer including the color developing composition, a method for producing a lithographic printing plate in which the lithographic printing plate precursor is used, and a compound represented by Formula 1.

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A color developing composition which develops colors in a high density and does not significantly discolor when aged, a lithographic printing plate precursor which has excellent plate-inspecting properties by means of color development and is capable of maintaining strong color development even when aged after color development, a plate making method for a lithographic printing plate in which the lithographic printing plate precursor is used, and a new compound that can be preferably used as a color developer. The color developing composition of the present invention includes a compound represented by Formula 1. The compound in the present invention is represented by Formula 1. In Formula 1, R.sup.1 represents a group in which an R.sup.1O bond is cleaved by heat or exposure to infrared rays. ##STR00001##

Provided are a planographic printing plate precursor for furnishing a planographic printing plate in which edge stain does not occur, adhesion to interleaving paper is prevented, and the water width with respect to edge stain at the time of printing is wide; a method of producing the same, and a printing method using the same. The planographic printing plate precursor including: a support; an image recording layer formed on the support; and a water-soluble compound having a molecular weight in a range of 60 to 300 and a solubility of 10 g/L or greater in water at 20 C., in which a content of the compound per unit area in a region on the image recording layer side from an end portion of the planographic printing plate precursor to a portion inside the end portion by 5 mm is greater than a content of the compound per unit area in a second region other than the first region by an amount of 50 mg/m.sup.2 or greater.

Provided are a planographic printing plate precursor for on-press development, including: an aluminum support; an interlayer which contains a compound containing a support absorptive group and a hydrophilic group; and an image recording layer which contains an infrared absorbing agent, a polymerization initiator, a polymerizable compound, and polymer particles formed of a styrene copolymer, on the aluminum support, in which the aluminum support is an aluminum plate having an anodized film on a surface in contact with the interlayer and the anodized film has micropores extending in a depth direction from a surface in contact with the interlayer, and an average pore diameter of the micropores in the surface of the anodized film is in a range of 20 to 40 nm; a method of preparing a planographic printing plate and a planographic printing method obtained by using the planographic printing plate precursor for on-press development.

An on-press development type lithographic printing plate precursor including a support, and an image-recording layer on the support, in which the image-recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and one or more compounds selected from the group consisting of a compound represented by Formula (1) and a compound represented by Formula (2) (in Formula (1) and (2), Ra.sub.1 and Ra.sub.2 represent an alkyl group, Rb.sub.1 and Rb.sub.3 represent an alkyl group, Rb.sub.2 and Rb.sub.4 represent an alkyl group, and EDG's each independently represent a hydrogen atom or an electron-donating group, provided that at least one of the four EDG's in Formula (1) represents an electron-donating group).

A lithographic printing plate precursor has a substrate comprising a hydrophilic surface and two opposing edges; a radiation-sensitive imagable layer, and optionally, a protective layer disposed over that layer. The precursor has a shear droop at each opposing edge, each shear droop having a shear droop depth Y of 20-200 m and a shear droop width X of 500-2000 m. The precursor also has a hydrophilic coating band extending from each of the two opposing edges inwardly along the hydrophilic surface independently to provide a hydrophilic coating band width A of at least 1.5 times the shear droop width X. This hydrophilic coating band comprises amphoteric surfactant(s) in an amount greater than all other surfactants. Such individual precursors are obtained by cutting a continuous radiation-sensitive web into strips and such cutting creates the shear droop that can result in edge staining if the hydrophilic coating band is not present.

Provided is a printing plate precursor including: a support; a layer which contains a polymer on one side of the support; and a layer which contains a metal oxide obtained by hydrolyzing and polycondensing an organic metal compound or an inorganic metal compound and fine particles on the other side of the support, in which an average particle diameter of the fine particles is 0.3 m or greater and is greater than the thickness of the layer containing a metal oxide and fine particles, and in a case where the printing plate precursors are laminated, dislocation in stacking precursors, adhesion between precursors, and scratches can be all prevented even without using interleaving paper.