Patent ID: 7851133

Claim:
A lithographic printing process which comprises the steps of: imagewise scanning with a laser a presensitized lithographic plate which comprises a hydrophilic support and an image-recording layer containing a polymerization initiator, an ethylenically unsaturated polymerizable compound having no adherence to the hydrophilic support, and an ethylenically unsaturated polymerizable compound having adherence to the hydrophilic support and a molecular structure comprising a polyoxyalkylene group to polymerize the ethylenically unsaturated polymerizable compounds within the exposed area; removing the image-recording layer within the unexposed area from the lithographic plate mounted on a cylinder of a printing press; and then printing an image with the lithographic plate mounted on the cylinder of the printing press, and wherein the ethylenically unsaturated polymerizable compound having adherence is represented by the formula (I): wherein each of R 1 , R 2 and R 3 independently is hydrogen, a halogen atom or an alkyl group having 1 to 6 carbon atoms; X is oxygen or imino; m is an integer of 2 to 6; n is an integer of 2 to 20; L 1 is a single bond or a divalent linking group selected from the group consisting of a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group, oxygen, sulfur, imino, a substituted imino group, carbonyl and a combination thereof; and Z is an acidic group having pKa of not higher than 7 selected from the group consisting of phenolic hydroxyl, —COOH, —SO 3 H, —OSO 3 H, —CONHSO 2 —, —SO 2 NHSO 2 — and —COCH 2 COCH 3 or an onium group selected from the group consisting of an ammonium group, a phosphonium group and a sulfonium group.