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 planographic printing plate precursor containing in the following order: an aluminum support; an image recording layer; and a protective layer, in which a thickness of the protective layer is 0.2 μm or greater, and in a case where a Bekk smoothness of a surface of an outermost layer at a side where the image recording layer is provided is 1000 seconds or less.

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.

The present disclosure provides 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 a contact angle of a water droplet on a surface of the outermost layer that is measured 2 seconds after the water droplet is landed by an airborne water droplet method is greater than 36°. The present disclosure also provides applications of the on-press development type lithographic printing plate precursor.

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.

The present invention relates to a printing plate including a first silicone layer and a second silicone layer which have different ink acceptabilities on a support. An object of the present invention is to provide a printing plate that dispenses with a development step and that has excellent image reproducibility, ink repellency, ink acceptability, and printing durability.

The present disclosure provides 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 contains a hydrophobic polymer, and a contact angle of a water droplet on a surface of the outermost layer that is measured 2 seconds after the water droplet is landed by an airborne water droplet method is less than 36°. The present disclosure also provides applications of the on-press development type lithographic printing plate precursor.

The present disclosure provides 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 contains a hydrophobic polymer, and a contact angle of a water droplet on a surface of the outermost layer that is measured 2 seconds after the water droplet is landed by an airborne water droplet method is less than 36°. The present disclosure also provides applications of the on-press development type lithographic printing plate precursor.