Lithographic printing plate precursors are prepared with a unique substrate and one or more radiation-sensitive imageable layers. The substrate is prepared by two separate anodizing processes to provide an inner aluminum oxide layer having an average dry thickness (T.sub.i) of 650-3,000 nm and a multiplicity of inner micropores having an average inner micropore diameter (D.sub.i) of 15 nm. A formed outer aluminum oxide layer comprises a multiplicity of outer micropores having an average outer micropore diameter (D.sub.o) of 15-30 nm; an average dry thickness (T.sub.o) of 130-650 nm; and a micropore density (C.sub.o) of 500-3,000 micropores/m.sup.2. The ratio of D.sub.o to D.sub.i is greater than 1.1:1, and D.sub.o in nanometers and the outer aluminum oxide layer micropore density (C.sub.o) in micropores/m.sup.2, are further defined by the outer aluminum oxide layer porosity (P.sub.o) according to the following equation:

0.3P.sub.o0.8

where P.sub.o is 3.14(C.sub.o)(D.sub.o.sup.2)/4,000,000.

A positive-working lithographic printing plate precursor includes a coating optimized for producing a minimum extent of ablation when exposed to heat and/or light. The coating includes an infrared absorbing agent which contains a structural element according to Formula I:

##STR00001##

wherein A represents SR.sup.1 wherein R.sup.1 represents an optionally substituted alkyl, aralkyl, alkaryl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl group, and/or combinations thereof; and Q=CHRCHR, CRCR or CHRCHRCHR and R, R and R independently represent hydrogen, an alkyl, cycloalkyl, aralkyl, alkaryl, aryl or heteroaryl group, or R and R or R and R form together a cyclic structure.

A lithographic printing plate precursor has a support and an image-recording layer on the support. 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.nPFormula (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.PnP) is 1 or less.

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)

A lithographic printing plate precursor has a substrate comprising a hydrophilic surface and two opposing edges; a radiation-sensitive imagable layer, and optionally, a protective layer disposed over that layer. The precursor has a shear droop at each opposing edge, each shear droop having a shear droop depth Y of 20-200 m and a shear droop width X of 500-2000 m. The precursor also has a hydrophilic coating band extending from each of the two opposing edges inwardly along the hydrophilic surface independently to provide a hydrophilic coating band width A of at least 1.5 times the shear droop width X. This hydrophilic coating band comprises amphoteric surfactant(s) in an amount greater than all other surfactants. Such individual precursors are obtained by cutting a continuous radiation-sensitive web into strips and such cutting creates the shear droop that can result in edge staining if the hydrophilic coating band is not present.

An on-press development type lithographic printing plate precursor includes a support and an image-recording layer on the support. The image-recording layer contains a polymerization initiator, an infrared absorber, a color forming substance precursor, and an auxiliary capable of donating an electron to the infrared absorber. A polymer having an ethylenically unsaturated group and a water-soluble monofunctional monomer are present on a surface of the support on an image-recording layer side, a layer in contact with the support on the image-recording layer side contains the polymer having an ethylenically unsaturated group and the water-soluble monofunctional monomer, or a layer in contact with the support on the image-recording layer side, other than the image-recording layer, contains the polymer having an ethylenically unsaturated group and the image-recording layer contains the water-soluble monofunctional monomer.

A method of making a lithographic printing plate includes the steps of a) image-wise exposing a lithographic printing plate precursor including a hydrophilic support and a coating containing a colorant precursor to form a lithographic image consisting of printing areas and non-printing areas, b) developing the plate precursor to remove the coating in the non-printing areas from the support, and c) drying the plate precursor, and d) subjecting the plate precursor to heat or radiation to induce a colour change of the coating in the printing areas, wherein before step b) the coating in the non-printing areas and the support are characterised by a CIE 1976 colour difference E.sub.1 which is 5.0 or less, and after step d) the CIE 1976 colour difference E.sub.2 between the coating in the printing areas and the non-printing areas is more than 6.8.

An on-press development type lithographic printing plate precursor, including an image-recording layer on a support, in which the image-recording layer contains an infrared absorber A, a borate compound B, an iodonium compound C, and a color forming substance precursor D, and a surface free energy of an outermost layer on an image-recording layer side is 115 mJ/m.sup.2 or less, and a method of preparing a lithographic printing plate, a lithographic printing method, and a laminate using the on-press development type lithographic printing plate precursor.

A photosensitive resin printing plate precursor is disclosed for relief printing, including a support, a photosensitive resin layer, and a cover film stacked in this order, wherein the photosensitive resin layer comprises a lower layer present on a support side and an upper layer present on a cover-film side, wherein the upper layer is a photosensitive resin layer that contains a water-soluble or water-dispersible resin (A) having a glass transition temperature measured by differential scanning calorimeter of 40 to 90 C., wherein the upper layer has a thickness of 3 to 30 micrometers, wherein the lower layer is a layer that contains a water-soluble or water-dispersible resin (B) having a glass transition temperature higher than the glass transition temperature of the water-soluble or water-dispersible resin (A) by 5 C. or more, and wherein the glass transition temperature of the resin (B) measured by differential scanning calorimeter is 95 to 135 C.

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 an infrared absorber, a polymerization initiator, a polymerizable compound, and a color-developing substance precursor, and in a case where the image-recording layer is exposed to an infrared laser having a wavelength of 830 nm at an energy density of 110 mJ/cm.sup.2, a loss of ethylenically unsaturated bonds in an exposed area in the image-recording layer is 10% to 40% of ethylenically unsaturated bonds in a non-exposed area in the image-recording layer, and a method for preparing a lithographic printing plate or a lithographic printing method using the on-press development type lithographic printing plate precursor.