Provided are a planographic printing plate precursor including a support and an image recording layer on the support, in which the image recording layer contains an organic particle containing a resin that has a constitutional unit A having a cation moiety and a constitutional unit B having an anion moiety; and a method of preparing a planographic printing plate using the planographic printing plate precursor.

IR-sensitive lithographic printing plate precursors provide a stable print-out image using a unique IR radiation-sensitive composition. This IR radiation-sensitive composition includes: a) free radically polymerizable component; an b) IR radiation absorber; c) an initiator composition; a d) borate compound; and a e) compound capable of forming a colored boronic complex during or after exposure of the infrared radiation-sensitive image-recording layer to infrared radiation. The resulting print-out image exhibits an excellent color contrast between the exposed and non-exposed regions. After IR imaging, these precursors can be developed off-press or on-press.

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 method of lithographic plate making is disclosed wherein a plate precursor is exposed to laser radiation in the wavelength range from 350 to 450 nm, said plate precursor comprising a hydrophilic support and a photopolymerizable or photocrosslinkable image recording layer, and then processed on-press by supplying fountain and ink. The exposure produces a visible image having a 1976 CIELAB color distance ΔE between exposed and non-exposed areas of at least 2.5.

A negative-working lithographic printing plate precursor includes a coating including vinylogous vitrimer particles. The vinylogous vitrimer particles include a resin having at least one moiety of formula (I), (II), and/or (III): ##STR00001##

Provided is a lithographic printing plate recursor having a support and an image-recording layer on the support, in which the image-recording layer contains an infrared absorber, a polymer A that has a weight-average molecular weight of more than 15,000 and 150,000 or less, and a polymerizable compound B that has a weight-average molecular weight of 1,000 or more and 15,000 or less, and the polymer A is a polymer represented by Formula (I).

A.sup.P-(B.sup.P).sub.nP  Formula (I)

In Formula (I), A.sup.P represents an nP-valent organic group having a hydrogen bonding group, B.sup.P represents a group having 2 or more Polymerizable groups, nP represents an integer of 2 or more, and weight-average molecular weight of A.sup.P/(molecular weight of B.sup.P×nP) is 1 or less.

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.

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 a conjugated carbon chain between the aromatic terminal groups. The compound also has a —SO.sub.2—R.sup.3 group wherein R.sup.3 represents 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 support and a coating including a polymerisable compound, an optionally substituted trihaloalkyl sulfone initiator, a leuco dye and a specific infrared absorbing compound including a six membered ring in the central position.

A lithographic printing plate precursor including an image recording layer on a hydrophilic support, in which the image recording layer includes a polymerization initiator, an infrared absorbent, a polymerizable compound, and an acid color former, and the infrared absorbent includes a compound represented by Formula 1, as well as a method of preparing a lithographic printing plate by use of the lithographic printing plate precursor. In Formula 1, at least one of Ar.sub.1 or Ar.sub.2 has a group represented by —X, where X represents a halogen atom, —C(═O)—X.sub.2—R.sub.11, —C(═O)—NR.sub.12R.sub.13, —O—C(═O)—R.sub.14, —CN, —SO.sub.2N.sub.15R.sub.16, or a perfluoroalkyl group, X.sub.2 represents a single bond or an oxygen atom, R.sub.11 and R.sub.14 each independently represents an alkyl group or an aryl group, and R.sub.12, R.sub.13, R.sub.15 and R.sub.16 each independently represents a hydrogen atom, an alkyl group, or an aryl group: ##STR00001##