Provided is a lithographic printing plate precursor having a support, an image-recording layer, and an overcoat layer in this order, in which the image-recording layer contains a polymerization initiator, a polymerizable compound, and particles, and the overcoat layer contains a discoloring compound. Also provided is a method of preparing a lithographic printing plate or a lithographic printing method that uses the lithographic printing plate precursor.

A lithographic printing plate precursor including an image recording layer containing an infrared absorber represented by Formula I, on a support, and a method of producing a lithographic printing plate and a lithographic printing method using the lithographic printing plate precursor. ##STR00001##

There are free radical scavengers of formula (P.sub.m-L).sub.n-T.sub.q. Also provided are negative-working lithographic printing plate precursors comprising a hydrophilic substrate and a NIR photopolymerizable or UV-violet photopolymerizable imageable layer coated on the hydrophilic layer, the imageable layer also being photopolymerizable by visible light, the imageable layer having an outer surface and a thickness, the outer surface of the imageable layer being uniformly, and partially or completely crosslinked down to a depth corresponding to at most about 70% of the thickness of the imageable layer.

The purpose of the present invention is to provide a planographic printing plate precursor which suppresses bleeding or transferring of a substance over time while maintaining edge stain preventing performance, a plate-making method of a planographic printing plate, and a printing method using the planographic printing plate. The planographic printing plate precursor includes a support; and an image recording layer formed on the support, in which layer arrangement described in any one of the following i to iv is provided, a hydrophilizatioin agent layer containing a hydrophilization agent is provided in a region in a specific position of the layer arrangement from the end portion of the planographic printing plate precursor to a portion inside the end portion by 1 cm, and the image recording layer includes an infrared absorbing agent and a specific radical polymerizable compound. i: a mode in which the support layer and the image recording layer are provided in this order. ii: a mode in which the support layer, an undercoat, and the image recording layer are provided in this order. iii: a mode in which the support layer, the image recording layer, and a protective layer are provided in this order. iv: a mode in which the support layer, the undercoat, the image recording layer, and the protective layer are provided in this order.

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. ##STR00001##

Provided is an on-press development type lithographic printing plate precursor having a support, an image-recording layer, and an outermost layer in this order, in which the outermost layer has a sea-island structure consisting of a discontinuous phase that contains a hydrophobic polymer and a continuous phase that contains a water-soluble polymer. Also provided are a method of preparing a lithographic printing plate and a lithographic printing method in which the on-press development type lithographic printing plate precursor is used.

Provided is an on-press development type lithographic printing plate precursor having a support, an image-recording layer, and an outermost layer in this order, in which the image-recording layer contains an infrared absorber, an electron-donating polymerization initiator, and a polymerizable compound, HOMO of the infrared absorber - HOMO of the electron-donating polymerization initiator is 0.60 eV or less, and the outermost layer contains a discoloring compound. Also provided are a method of preparing a lithographic printing plate and a lithographic printing method in which the on-press development type lithographic printing plate precursor is used.

A lithographic printing plate precursor is disclosed which comprises a support, a photopolymerizable image recording layer and an overcoat which comprises a low-molecular radical inhibitor. After image-wise exposure, the plate is heated whereby the radical inhibitor diffuses from the overcoat to the image recording layer, resulting in an increase of the daylight stability of the exposed and heated precursor. Such plate is especially suitable for on-press processing.

A lithographic printing plate precursor is disclosed including a support and a coating comprising (i) a photopolymerisable layer including a polymerisable compound, a photoinitiator and an asymmetrically substituted infrared absorbing compound.

A lithographic printing plate precursor has an image-recording layer on a hydrophilic support, in which the image-recording layer contains an infrared absorbing dye that decomposes by exposure to an infrared ray and a color developer that develops color due to the exposure to an infrared ray. A method for producing a lithographic printing plate includes image-exposing the lithographic printing plate precursor using an infrared laser.