Provided is a lithographic printing method including a preparing step of preparing a lithographic printing plate precursor which includes an aluminum support, and an image recording layer containing an acid color developing agent and an acid generator on the aluminum support, an exposing step of exposing the lithographic printing plate precursor, a developing step of supplying acidic dampening water to the exposed lithographic printing plate precursor and removing a non-image area of the image recording layer, and a printing step, in which the aluminum support includes an anodized aluminum film, the anodized film has micropores, and a value ΔS is 15% or greater and 60% or less.

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-accepting polymerization initiator, and a polymerizable compound, LUMO of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.45 eV or more, and the outermost layer contains a discoloring compound. Also provided is 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 are a planographic printing plate precursor including a support, and an image recording layer on the support, in which the image recording layer contains an infrared absorbing agent, a polymerization initiator, and a core-shell particle, a core portion of the core-shell particle contains a resin A containing a functional group A, and a shell portion of the core-shell particle contains a resin B containing a functional group B that is bondable to or interactable with the functional group A and a dispersion group; a method of preparing a planographic printing plate using the planographic printing plate precursor; and a planographic printing method carried out using the planographic printing plate precursor.

Provided are an on-press development type lithographic printing plate precursor having a support and an image-recording layer on the support in which the image-recording layer contains a coloring compound capable of having a coloring reaction with a decomposition product generated by exposure of the image-recording layer, and an on-press development type lithographic printing plate precursor having a support and an image-recording layer on the support in which the image-recording layer contains a compound represented by Formula 1C or Formula 2C and an electron-donating polymerization initiator. In Formula 1C and Formula 2C, R.sup.1C to R.sup.4C each independently represent a monovalent organic group, L.sup.1C and L.sup.2C each independently represent a divalent organic group, A.sup.C represents OH or NR.sup.5CR.sup.6C, and R.sup.5C and R.sup.6C each independently represent a monovalent organic group.

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An object of the present invention is to provide a lithographic printing plate precursor which has excellent on-press developability and is capable of suppressing generation of slip stains and from which a lithographic printing plate with satisfactory printing durability is obtained, and a method of producing a lithographic printing plate and a printing method using the lithographic printing plate precursor. The lithographic printing plate precursor of the present invention is a lithographic printing plate precursor including an aluminum support, and an image recording layer, in which the aluminum support includes an aluminum plate and an anodized aluminum film disposed on the aluminum plate, the anodized film is positioned on a side of the image recording layer with respect to the aluminum plate, the anodized film has micropores extending from a surface of the anodized film on the side of the image recording layer in a depth direction, the micropores have an opening ratio of 20% to 70%, a steepness a45 on the surface of the anodized film on the side of the image recording layer is in a range of 3% to 25%, and an arithmetic average roughness Ra on the surface of the anodized film on the side of the image recording layer is in a range of 0.25 to 0.60 μm.

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 top layer provided above the photopolymerisable layer; characterized in that the top layer includes a non-polymeric polyfunctional compound in an amount between 2 mg/m.sup.2 and 80 mg/m.sup.2 which comprises at least two carboxyl and/or carboxylate groups.

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 an indene ring in the conjugated chain between the aromatic terminal groups. The compound can also have a —C(═O)—OR.sup.7, —SO.sub.2—R.sup.3, or —SO.sub.2NR.sup.8R.sup.9 group wherein R.sup.7 represents a substituted or unsubstituted alkyl group having a secondary or tertiary connecting carbon that connects to the rest of the —C(═O)—OR.sup.7 group; and R.sup.8, R.sup.9, and R.sup.10 independently represent substituted or unsubstituted 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 lithographic printing plate precursor is disclosed including a coating comprising a polymerisable compound, an infrared absorbing dye, a photoinitiator including a trihaloalkyl group and a borate compound.

Provided is an on-press development type lithographic printing plate precursor having two or more maximal absorption wavelengths in a wavelength range of 760 nm to 900 nm, in which in a case where the on-press development type lithographic printing plate precursor is subjected to exposure to infrared having a wavelength of 830 nm at an energy density of 110 mJ/cm.sup.2, in a portion subjected to the exposure, a brightness change ΔL before the exposure and after storage subsequent to the exposure for 24 hours under conditions of 25° C. and 70% RH is 3.0 or more. 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 a laminate including a lithographic printing plate precursor and interleaving paper, in which the lithographic printing plate precursor is an on-press development type lithographic printing plate precursor containing an acid color developing agent in at least any of layers, and a pH of the interleaving paper is 5 or more.