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.

An on-machine development lithographic printing plate precursor includes an image-recording layer on an aluminum support having an anode oxide film, wherein an end portion of the lithographic printing plate precursor has a shear droop shape, the image-recording layer contains a compound having a support adsorptive property, having a molecular weight of 1,000 or less, and not having an unsaturated double bond group in a molecule, and a content of the compound is substantially the same in a plane of the image-recording layer.

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 has an image-recording layer on a hydrophilic support, wherein the image-recording layer includes a polymer particle including an addition polymerization resin having a hydrophilic structure and a crosslinking structure. A method for producing a lithographic printing plate uses the lithographic printing plate precursor. A polymer particle includes an addition polymerization resin having a hydrophilic structure and a crosslinking structure. A composition includes the polymer particle.

Provided are a planographic printing plate precursor including an aluminum support, and an image recording layer and a protective layer which are provided on the aluminum support in this order, in which a thickness of the protective layer is 0.2 μm or greater, and Expression (1) is satisfied in a case where a Bekk smoothness of a surface of an outermost layer on a side opposite to a side where the image recording layer is provided is denoted by b seconds; a planographic printing plate precursor laminate; a plate-making method for a planographic printing plate; and a planographic printing method.

A lithographic printing plate precursor including a hydrophilized aluminum support, and a water-soluble or water-dispersible negative type image recording layer provided on the aluminum support, in which an arithmetic average height Sa of a surface of an outermost layer on a side where the image recording layer is provided is in a range of 0.3 μm to 20 μm; a method of producing a lithographic printing plate precursor; a lithographic printing plate precursor laminate formed of the lithographic printing plate precursor; a plate-making method for a lithographic printing plate; and a lithographic printing method.

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.

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.