Provided is a positive type lithographic printing plate precursor including at least: a support which has a hydrophilic surface or a hydrophilic layer; and an underlayer, an interlayer, and an upper layer on the support in this order, in which the underlayer contains a polymer compound 1 which has at least one structure selected from the group consisting of a urethane bond, an acetal structure, and a urea bond in a main chain, the interlayer contains a polymer compound 2 which has at least one structure selected from the group consisting of a sulfonamide group, an active imide group, and a urea bond in a side chain, the upper layer contains a polymer compound 3 which has a phenolic hydroxy group, and one or more layers among the underlayer, the interlayer, and the upper layer contain an infrared absorbent. Further, provided are a method of producing the positive type lithographic printing plate precursor and a method of preparing a lithographic printing plate using the positive type lithographic printing plate precursor.

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 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 a halogenated polymer and a nitrite and/or nitrate salt.

The present invention provides a printing plate precursor including a layer which includes a polymer and is provided on a printing surface side of an aluminum support, and a layer which includes particles and is provided on a side opposite to the printing surface side, in which a modulus of elasticity of the particles is 0.1 GPa or more, and in a case where a Bekk smoothness of an outermost layer surface on the side opposite to the printing surface side is denoted by b second, a specific expression (1) is satisfied; a printing plate precursor laminate; a method for making a printing plate; and a printing method.

A planographic printing plate precursor having an image recording layer on a support, and an overcoat layer in this order, in which the overcoat layer includes particles, the overcoat layer is an outermost layer, and an occupation area ratio of the particles in a surface of the overcoat layer is 30% by area or more; and a method of producing a planographic printing plate obtained by using the planographic printing plate precursor.

A laser-engravable pad printing plate comprising at least (a) a metal support, (b) an adhesion layer, (c) a laser-engravable recording layer having a layer thickness of 20 ?m to 200 ?m, (d) a cover film,
characterized in that the laser-engravable recording layer (c) comprises (c1) 40 to 95 wt % of a polyvinyl alcohol, (c2) 5 to 50 wt % of an IR absorber, (c3) 0 to 30 wt % of an inorganic filler, (c4) 0 to 20 wt % of a crosslinker, and (c5) 0 to 10 wt % of further additives.

An on-machine development type planographic printing plate precursor has a support and an image-recording layer on the support. The image-recording layer contains an initiator, an infrared absorber capable of donating electrons to the initiator, and a color-developing substance precursor. The image-recording layer can form an image by exposure to infrared laser, and in a case where the image-recording layer is exposed to an infrared laser with a wavelength of 830 nm at an energy density of 110 mJ/cm.sup.2, a brightness change L of the image-recording layer before and after the exposure is 3.0 or more. A method for preparing a planographic printing plate and a planographic printing method employ the on-machine development type planographic printing plate precursor.

A method for manufacturing a lithographic printing plate precursor includes the steps of providing a support as a web, coating an image recording layer on the front side of the support, and depositing a back layer on the back side of the support using a deposition technique which is capable of depositing the back layer according to a predefined image. The method enables stacking and recutting of lithographic printing plate precursors without the need for interleafs.

A method for manufacturing a lithographic printing plate precursor includes the steps of providing a support as a web, coating an image recording layer on the front side of the support, and depositing a back layer on the back side of the support using a deposition technique which is capable of depositing the back layer according to a predefined image. The method enables stacking and recutting of lithographic printing plate precursors without the need for interleafs.

The invention is directed to a lithographic printing plate precursor including, in the following order: a support; an image-recording layer containing a radical polymerizable compound and a radical polymerization initiator; and a protective layer containing a star polymer, and the star polymer is preferably a polymer in which from 3 to 10 polymer chains are branched from a central skeleton.