A lithographic printing plate precursor having an image-recording layer on a hydrophilic support, in which the image-recording layer includes an organic polymer particle, and the organic polymer particle is a reaction product obtained by at least reacting an aromatic polyvalent isocyanate compound having a structure represented by Formula PO and water, a method for making a lithographic printing plate having excellent printing resistance in the case of using an ultraviolet-curable ink in printing, a new organic polymer particle, and a resin composition including the organic polymer particle. ##STR00001##

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.

A source of actinic radiation for curing printing plates. The source includes a base with a heat sink and has a length greater than its width. One or more circuit boards mounted on the base provide a plurality of light emitting diodes (LEDs) distributed over the length of the base. A transparent or translucent cover together with the base defines an enclosure for the plurality of LEDs. The source provides the radiation at an emission angle greater than the emission angles of a single LED in a plane perpendicular to the axis of the base, in a plane containing the axis of the base or parallel to the axis of the base and perpendicular to the target illumination plane, or a combination thereof. The source may be configured to replace a fluorescent bulb. Methods and systems for bank exposure of printing plates using such sources are also described.

Provided is a planographic printing plate precursor including: a support; and an image recording layer formed on the support, in which a region on the plate surface on the image recording layer side from an end portion of the planographic printing plate precursor to a portion inside the end portion by 5 mm contains a polymer containing a functional group represented by the following Formula (A), and the content of the polymer per unit area in the region is greater than the content of the polymer per unit area in a region other than the above-described region by an amount of 10 mg/m.sup.2 or greater.

—Si(X).sub.m(R.sup.3).sub.n  (A)

Provided is a lithographic printing plate precursor having a support and an image-recording layer on the support, in which the image-recording layer has an infrared absorber, a polymerization initiator, a polymerizable compound 1, a polymerizable compound 2, and a polymerizable compound 3, in which a molecular weight of the polymerizable compound 1 is less than 1,000, a weight-average molecular weight of the polymerizable compound 2 is 1,000 or more and 3,000 or less, and a weight-average molecular weight of the polymerizable compound 3 is more than 3,000 and 15,000 or less.

Provided is 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 A that has a partial structure satisfying Δd≥15.5 wherein δd is a value of a dispersion element in the Hansen solubility parameters, and a content of the partial structure satisfying Δd≥15.5 in the compound A is 50% by mass or more with respect to a total mass of the compound. Also provided is a method of preparing lithographic printing plate or a lithographic printing method using the lithographic printing plate precursor.

lithographic printing plate precursor including on a substrate which has a hydrophilic surface or which is provided with a hydrophilic layer, a coating comprising a photopolymerisable layer including a polymerisable compound, a photoinitiator and adhesion promoting compound containing at least one thiol group and at least one group capable of adhering to the substrate.

A lithographic printing plate precursor includes an image recording layer on a support, in which the lithographic printing plate precursor has projections which are discontinuously formed on a surface of an outermost layer on a side where the image recording layer is provided, and a melting point of each projection is in a range of 70° C. to 150° C. A method of producing a lithographic printing plate includes a step of image-wise exposing the lithographic printing plate precursor to form an exposed portion and an unexposed portion, and a step of supplying at least one of printing ink or dampening water to remove the unexposed portion.

Provided is a lithographic printing plate precursor having a support and an image-recording layer on the support, in which the image-recording layer contains an infrared absorber, a polymerization initiator, and a polymer A, a weight-average molecular weight of the polymer A is more than 15,000 and 150,000 or less, and an ethylenically unsaturated bond valence of the polymer A is 3.0 mmol/g or more.

Provided is a lithographic printing plate precursor having an aluminum support and an image-recording layer on the aluminum support, in which the image-recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and an addition polymerization-type resin having a dispersible group, and in a case where a capacitance Cp of the lithographic printing plate precursor is set to satisfy Cp (t)/Cp (20 seconds)=0.95, t satisfies t<12 seconds or the capacitance Cp of the lithographic printing plate precursor satisfies Cp (0 seconds)>400 nF. Also provided are a method for preparing lithographic printing plate or a lithographic printing method using the lithographic printing plate precursor. The capacitance Cp of the lithographic printing plate precursor is measured by bringing at least a measurement portion of the image-recording layer into contact with a 2% by mass aqueous sodium chloride solution at 25° C.