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.

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 an aluminum support, an image-recording layer, and a water-soluble overcoat layer in this order, in which the image-recording layer contains an infrared-absorbing polymethine colorant having HOMO of −5.2 eV or less, a polymerization initiator, a polymerizable compound, and a polymer, and the polymer has a constitutional unit formed of an aromatic vinyl compound and a constitutional unit formed of an acrylonitrile compound. Also provided are a method for preparing a lithographic printing plate using the lithographic printing plate precursor.

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.

Provided is an on-press development type 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-absorbing polymethine colorant having HOMO of −5.2 eV or less, a polymerization initiator, and a polymerizable compound having 7 or more functional groups and contains or does not contain a polymer having a molecular weight 10,000 or more, and in a case where the image-recording layer contains the polymer having a molecular weight of 10,000 or more, a ratio Wp/Wm of a content Wp of the polymer having a molecular weight of 10,000 or more to a content Wm of the polymerizable compound having 7 or more functional groups is 1.00 or less. Also provided are a method for preparing a lithographic printing plate and a lithographic printing method using the lithographic printing plate precursor.

Provided is an on-machine development type planographic printing plate precursor having a support and an image-recording layer on the support, in which 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 ΔL of the image-recording layer before and after the exposure is 3.0 or more. Also provided are a method for preparing a planographic printing plate or a planographic printing method in which the on-machine development type planographic printing plate precursor is used.

A lithographic printing plate precursor has an infrared radiation-sensitive image-recording layer containing an IR absorber, and an ozone-blocking material of 1500 or less molecular weight and has structure (I), (II), or (III):

##STR00001##

wherein R is a hydrocarbon having 14-30 carbon atoms; m is 1 or 2; n is 1-6; the sum of m and n is >2 and <8; and A is a multivalent organic moiety free of R and OH groups and has a valence m+n;

##STR00002##

wherein R.sub.1 and R.sub.2 are alkyl groups of 14-22 carbon atoms, and o is 1-3;

R.sub.3C(═O)NR.sub.4R.sub.5   (III)

wherein R.sub.3 is an alkenyl with a C═C bond within a carbon-carbon chain of 16-30 carbons, and R.sub.4 and R.sub.5 are hydrogen or unsubstituted alkyls of 1-4 carbon atoms. Such ozone-blocking materials can be used to protect infrared radiation-sensitive dyes that may be degraded by ozone and thus improve imaging sensitivity.

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.

Provided are a planographic printing plate precursor including a support, and an image recording layer in this order, in which the image recording layer contains polymer particles containing an addition polymerization type resin, and the addition polymerization type resin contains a polymerizable group and a hydrophilic structure; a method of producing a planographic printing plate using the planographic printing plate precursor; a planographic printing method using the planographic printing plate precursor; and a curable composition containing the polymer particles.