Photosensitive lithographic printing plate and method for making a printing plate
AssigneeLastra S.p.A.
InventorsToshiyuki Urano, Kazuhiro Kohori, Hideaki Okamoto
Life of this patent
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Abstract
A photosensitive lithographic printing plate comprises a photosensitive layer and a protective layer formed in this order on a support, wherein the photosensitive layer has a maximum peak of spectral sensitivity within a wavelength range ranging from 390 to 430 nm, the minimum exposure for the photosensitive lithographic printing plate for image formation at a wavelength of 410 nm (S410) is at most 100 μJ/cm2, and the relation between the minimum exposure for image formation at a wavelength of 450 nm (S450) and the minimum exposure for image formation at a wavelength of 410 nm (S410) is 0<S410/S450≦0.1.
Claims23
A method for making a printing plate, said method comprising:
- a) image exposing to laser light having a wavelength ranging from 390 to 430 nm a photosensitive lithographic printing plate comprising a photosensitive layer and a protective layer formed in this order on a support, to obtain an exposed plate, wherein the minimum exposure for said photosensitive lithographic printing plate for image formation at a wavelength of 410 nm (S410) is at most 100 μJ/cm2, and the relation between the minimum exposure for image formation at a wavelength of 450 nm (S450) and the minimum exposure for image formation at a wavelength of 410 nm (S410) is 0<S410/S450≦0.1;
- and
- b) developing said exposed plate with an aqueous developer,
- wherein said photosensitive layer comprises (A) an ethylenic monomer, (B) a sensitizing pigment, and (C) a radical generator, and wherein said ethylenic monomer comprises a urethane compound (a3) having at least four urethane linkages and at least four addition-polymerizable double bonds in one molecule.
Dependencies are inferred from the claim text.