A negative-working infrared radiation-sensitive lithographic printing plate precursor can be imaged and developed on-press to provide a lithographic printing plate. Such precursor has an initiator composition that contains compound A of Structure (I) and one or more compounds collectively as compound B of Structure (II) or Structure (III): ##STR00001##
wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are independently alkyl groups each having 3 to 6 carbon atoms; at least one of R.sub.3 and R.sub.4 is different from R.sub.1 or R.sub.2; the difference of total number of carbon atoms in R.sub.1 and R.sub.2 and the total number of carbon atoms in R.sub.3 and R.sub.4 is 0, 1, or 2; the difference of total number of carbon atoms in R.sub.1 and R.sub.2 and the total number of carbon atoms in R.sub.5 and R.sub.6 is 0, 1, or 2; and X.sub.1, X.sub.2 and X.sub.3 are the same or different anions.

IR-sensitive lithographic printing plate precursors provide a high contrast and stable printout image using an IR radiation-sensitive composition. This composition includes: a free radically polymerizable component, an IR absorber, an initiator composition, color-forming compound(s) such as a specific leuco dye, and compound(s) represented by the following Structure (P):

##STR00001##

wherein X is O, S, NH, or CH.sub.2, Y is >N or >CH, R.sup.1 is hydrogen or an alkyl, R.sup.2 and R.sup.3 are independently halo, thioalkyl, thiophenyl, alkoxy, phenoxy, alkyl, phenyl, thioacetyl, or acetyl, and m and n are independently 0 or an integer of 1 to 4. The printout image exhibits a color contrast between the exposed and non-exposed regions of a E greater than 8. A E of at least 5 is maintained between the exposed and the non-exposed regions with exposure to white light for at least one hour. These precursors, when IR-exposed, can be developed on-press.

Lithographic printing plate precursors are prepared with a unique substrate using two separate anodizing processes to provide an inner aluminum oxide layer of average dry thickness (T.sub.i) of 650-3,000 nm and a multiplicity of inner micropores of average inner micropore diameter (D.sub.i) of 15 nm. An outer aluminum oxide layer comprises a multiplicity of outer micropores of average outer micropore diameter (D.sub.o) of 15-30 nm; 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. A hydrophilic layer disposed on the outer aluminum oxide layer has a copolymer composed of (a) recurring units and (b) recurring units, wherein the (a) recurring units have an amide group, and the (b) recurring units have at least a phosphonic acid, a phosphoric acid, a salt of a phosphonic acid, or a salt of a phosphoric acid group.

A method for making a lithographic printing plate is disclosed including the steps of (i) image-wise exposing a printing plate precursor to heat and/or IR radiation; said precursor including a support and a coating comprising a polymerisable compound, an infrared absorbing compound, a borate compound and a photoinitiator including a trihaloalkyl group; (ii) developing the exposed precursor by treating the coating of the precursor with a gum solution thereby removing the coating from the support at the non-image areas; and/or by mounting the precursor on a plate cylinder of a lithographic printing press and rotating the plate cylinder while feeding dampening liquid and/or ink to the precursor.

The invention relates to a method (100) for producing an image structure (12) according to an image specification (20), in particular for a letterpress process and/or intaglio printing process, characterized in that the following steps are carried out: a) providing a base (10) for receiving the image structure (12), b) producing an image structure (12) on the base (10) so that an image layer (11) is formed on the base (10) by means of the image structure (12).

A lithographic printing plate precursor is disclosed including a coating comprising a polymerisable compound, an infrared absorbing dye, a photoinitiator including a trihaloalkyl group and a borate compound.

A system for preparing a photopolymer printing plate includes an imager, a plate unloader configured to automatically unload the plate from the imager and deliver the plate to an exposure unit comprising a plurality of UV LEDs, and a controller configured to operate the imager, the plate unloader, and the exposure unit. The imager has a rotatable drum configured to rotate while laser beams ablate portions of an ablatable layer of the printing plate in accordance with imaging data. The UV LEDs include a back array and a front array configured to expose the front of the UV-curable plate, at least one of which is configured to emit UV radiation toward the plate during relative motion between the plate and the array.

Provided is a precursor for lithographic printing having excellent printing durability and ink repellency as well as high reproducibility of the high definition images. The precursor for lithographic printing includes, at least a heat sensitive layer and an ink repellent layer wherein the ink repellent layer has an elastic modulus of the plate surface under the surface load of 14000 N/m2 of at least 25 MPa and up to 35 MPa.

Provided are a planographic printing plate precursor including a support and an image recording layer formed on the support, in which the image recording layer contains a polymer A which includes a constitutional unit A1 having an ethylenically unsaturated group, a weight-average molecular weight of the polymer A is in a range of 2,500 to 35,000, and a content of the constitutional unit A1 in the polymer A is 15 mol % or more, and a method of producing a planographic printing plate using the planographic printing plate precursor.

Provided are a lithographic printing plate precursor including an image recording layer on a support, in which a hydrophobic area is existed at at least a part of a surface of an outermost layer on a side where the image recording layer is provided and an occupation area ratio of the hydrophobic area in the surface of the outermost layer is more than 20% by area and less than 100% by area; and a method of producing a lithographic printing plate using the lithographic printing plate precursor.