The blanket cylinder of a printing press is used to remove oleophobic debris from an imaged dry printing member. Following imaging—e.g., imagewise exposure of the printing member to radiation that ablates the layer below the oleophobic layer, or de-anchors it from the oleophobic layer without ablation—the printing member is brought into rolling contact with the blanket cylinder, and the press is operated “on impression.” This rolling contact may remove not only the oleophobic top layer but ablation debris of the underlying imaging layer as well.

A positive-working lithographic printing plate precursor is disclosed which comprises on a support having a hydrophilic surface or which is provided with a hydrophilic layer a heat and/or light-sensitive coating including an infrared absorbing agent, said heat and/or light-sensitive coating comprising a first layer comprising a binder including a monomeric unit including a sulfonamide group; characterized in that the binder further comprises a monomeric unit including a phosphonic acid group or a salt thereof, and that the monomeric unit comprising the phosphonic acid group is present in an amount comprised between 2 mol % and 15 mol %.

An object of the present invention is to provide a waterless lithographic printing plate precursor that sufficiently repels ink, which tends to adhere to non-imaging areas, and maintains its repelling effects, and a printing method using a waterless lithographic printing plate obtained from the waterless lithographic printing plate precursor. The following are provided: a lithographic printing plate precursor having at least a heat sensitive layer and an ink repellent layer, wherein the ink repellent layer contains an ink repelling, the ink repellent liquid having a boiling point of not less than 150° C. at 1 atmospheric pressure; and a method of producing a printed material, comprising the step of transferring an ink containing a photosensitive component in an amount from 10% by mass to 50% by mass to a printing substrate using a lithographic printing plate and then irradiating the printing substrate with ultraviolet light, wherein the lithographic printing plate precursor has at least an ink repellent layer on a substrate, an ink repellent liquid contained in the ink repellent layer has a surface tension of 30 mN/m or less.

An object of the invention is to provide a water-based lithographic printing method that is excellent in printing quality and environmental aspects. The invention concerns a method of producing a printed material, including the steps of: allowing a water-based ink to adhere to a surface of a heat sensitive layer of a lithographic printing plate having a surface on which an ink repelling layer and the heat sensitive layer exist; and transferring the adhering water-based ink directly or via a blanket to a printing substrate.

Disclosed is a infrared radiation sensitive positive-working imageable element. The imageable element comprises: (a) a substrate, (b) an inner coating covering the substrate, and (c) an outer coating covering the inner coating. The inner coating comprises a repeating unit derived from a maleimide monomer and a (meth)acrylamide monomer, and a polymer hinder P that is soluble in an alkaline developing solution; and the outer coating comprises an infrared radiation absorbing compound and a polymer binder Q which is different from that in the inner coating. The imageable element is designed such that same is not only sensitive to radiation with a maximum wavelength of 700-1200 nm, but also has a good resistance to chemical solvents when used as a lithographic printing plate precursor, and same is not easily corroded and dissolved by printing chemicals during use, thus facilitating the prolonging of the service life of a lithographic printing plate.

A method for processing a heat-sensitive positive-working lithographic printing plate material is disclosed which comprises at least two layers: —a first layer comprising an oleophilic resin and/or a vinyl acetal (co)polymer; —a second layer comprising a (co)polymer which is located between the support and the first layer; comprising the steps of: —treating the plate material with an alkaline development solution, —treating the plate material with a first gum solution and consecutively with a second gum solution which are configured as a cascade whereby the second gum solution overflows into the first gum solution; and which gum solutions include a buffer; characterized in that the pH of the first gum solution reaches a steady state value above the pKa value of the (co)polymer present in the second layer.

Embodiments of the present invention involve three-layer printing members having a central layer that is non-conductive yet abalatable at commercially realistic fluence levels. In various embodiments, the central layer is polymeric with a dispersion of nonconductive carbon black particles therein at a loading level sufficient to provide at least partial layer ablatability and water compatibility of the resulting ablation debris.

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 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.

The present invention aims at providing a lithographic printing plate precursor, a lithographic printing plate manufacturing method, a printing method and an aluminum support manufacturing method that enable the resulting lithographic printing plate to have a long tiny dot press life. The lithographic printing plate precursor of the invention is a lithographic printing plate precursor having an aluminum support and an image recording layer disposed above the aluminum support. When measured over a 400 m400 m region of a surface of the aluminum support on the image recording layer side using a three-dimensional non-contact roughness tester, pits with a depth from centerline of at least 0.70 m are present at a density of at least 3,000 pits/mm.sup.2; and a surface area ratio S is not less than 35%, the surface area ratio S being determined using an actual area S.sub.x obtained, through three-point approximation, from three-dimensional data acquired by measurement at 512512 points in 25 m square of the surface of the aluminum support on the image recording layer side by means of an atomic force microscope and a geometrically measured area S.sub.o.