Disclosed is a heat-sensitive processless planographic printing plate material containing a thermosensitive protection layer. The planographic printing plate material sequentially comprises a supporting body, a hydrophilic layer, a heat-sensitive layer and a thermosensitive protection layer from the bottom up. The thermosensitive protection layer therein can not only isolate oxygen and protect the heat-sensitive layer from oxygen inhibition, but can also sense heat and allow a polymerization reaction to take place. Thus the binding force between same and the next layer is improved, so that the precision of printing plate images is high, the development performance is good, and the pressrun is high.

A polymerizable composition is provided, including an infrared absorber, a polymerization initiator, a polymerizable compound, and a polymer binder, wherein the polymer binder is a particulate random copolymer, and the polymer binder has structural units derived from a polymerizable polyalkylene oxide-based monomer and a polymerizable nitrogen-free non-polyalkylene oxide-based monomer. The polymerizable composition may be used in the production of imageable elements or printing plates.

Provided are a lithographic printing plate precursor including an aluminum support, and an image recording layer on the aluminum support, in which the aluminum support includes an anodized film on a surface of the image recording layer side, the anodized film has micropores extending in a depth direction from the surface of the anodized film on the image recording layer side, an average pore diameter of the micropores in the surface of the anodized film is greater than 0 m and 0.03 m or less, an average maximum diameter of the micropores inside the anodized film is in a range of 0.04 m to 0.30 m, an average value A nm of thicknesses of surface opening portions and an average value B nm of thicknesses of internal maximum diameter portions satisfy a relationship of 2.5B/A28.0, and the image recording layer contains an acid color former; a method of preparing a lithographic printing plate using the lithographic printing plate precursor; and a lithographic printing method.

On-press developable, negative-working lithographic printing plate precursors are used to provide lithographic printing plates. Such precursors are prepared with a substrate and one or more negative-working, infrared radiation-sensitive imagable 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 inner micropores having an average inner micropore diameter (D.sub.i) of <15 nm. A formed outer aluminum oxide layer comprises 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) as:
0.3P.sub.o0.8
wherein P.sub.o is 3.14(C.sub.o)(D.sub.o.sup.2)/4,000,000.

Provided are a lithographic printing plate precursor including a hydrophilized aluminum support, and a water-soluble or water-dispersible negative type image recording layer provided on the aluminum support, in which an arithmetic average height Sa of a surface of an outermost layer on a side where the image recording layer is provided is in a range of 0.3 m to 20 m or in which Expression (1) and Expression (2) are satisfied in a case where a Bekk smoothness of a surface of an outermost layer on a side where the image recording layer is provided is set as a seconds and a Bekk smoothness of a surface of an outermost layer on a side opposite to a side where the image recording layer is provided is set as b seconds; a method of producing the same; a lithographic printing plate precursor laminate formed of the lithographic printing plate precursor; a plate-making method for a lithographic printing plate; and a lithographic printing method.

a1000,b1000(1)

1/a+1/b0.002(2)

Provided are a lithographic printing plate precursor including: a hydrophilized aluminum support, and a water-soluble or water-dispersible negative type image recording layer provided on the aluminum support, in which an arithmetic average height Sa of a surface of an outermost layer on a side opposite to a side where the image recording layer is provided is in a range of 0.3 m to 20 m; a method of producing the lithographic printing plate precursor; a lithographic printing plate precursor laminate formed of the lithographic printing plate precursor; and a lithographic printing method.

Provided are a thermal fusion-type lithographic printing plate precursor in which the visibility is excellent, ablation during laser exposure is suppressed, and the contamination of dampening water and printing ink during on-machine development is suppressed by a lithographic printing plate precursor having a support and an image-recording layer, in which the image-recording layer is capable of forming an image by infrared laser exposure, a non-exposed portion of the image-recording layer is removable by at least one of dampening water and printing ink on a printer, and the image-recording layer contains (1) a color developing system in which a hue change generated by infrared laser exposure is a/b0.6 and (2) 70% by mass or more of a thermoplastic polymer particle with respect to a solid content of the image-recording layer and a plate-making method in which the thermal fusion-type lithographic printing plate precursor is used.

Provided are a color developing composition including a compound represented by Formula 1, a lithographic printing plate precursor having at least a layer including the color developing composition, a method for producing a lithographic printing plate in which the lithographic printing plate precursor is used, and a compound represented by Formula 1.

##STR00001##

The invention relates to an imageable coating layer, thermal negative-working lithography printing plate, and platemaking method. The coating layer includes constituents in parts by weight: a radically polymerizable compound 20-60 parts, a radiation-absorbing compound 0.5-12 parts, a free radical initiator 1-25 parts, a binding agent 10-70 parts, and a development accelerator 0.5-15 parts. The platemaking method includes the steps: S1, preparing a printing plate precursor that includes a substrate having a hydrophilic surface or is provided with a hydrophilic layer and imageable coating layer covering the substrate; S2, patternedly exposing the printing plate precursor, forming an exposed area and an unexposed area; and S3, removing the unexposed area via a development process. The employment of the imageable coating layer and the plate making method allows the implementation of a flexible development process of on-press development or off-press development and produces a printing plate provided with great printing performance.

A curable composition includes an infrared absorber having at least one element in Group XIII of the periodic table on a mother nucleus structure and having a chain-like polymethine structure, in which two or more hetero atoms are bonded to carbon atoms at non-meso positions. Also, a lithographic printing plate precursor in which the curable composition is used, and a method for producing a lithographic printing plate in which the lithographic printing plate precursor is used are provided.