Abstract: Provided is an imageable composition for a photosensitive negative-working lithographic printing plate, and a platemaking method therefor. The imageable composition includes the following components in parts by mass: 25-65 parts of a free radical polymerizable compound, 0.5-25 parts of a photoinitiator, 10-60 parts of a binder, and 1-20 parts of a development accelerator. The platemaking method may comprise coating a substrate, which may have a hydrophilic surface or a hydrophilic layer, with an imageable composition to obtain a photosensitive negative-working lithographic printing plate precursor. The method may additionally include exposing the lithographic printing plate precursor by using laser light and according to a required image, so as to form an exposed region and an unexposed region. Further the method may include removing the unexposed region from the exposed printing plate precursor by means of a development process, so as to obtain a required lithographic printing plate.

Abstract: Disclosed is a infrared radiation sensitive positive-working imageable element. The imageable element comprises: (a) a substrate, (b) an inner coating covering the substrate, and (c) an outer coating covering the inner coating. The inner coating comprises a repeating unit derived from a maleimide monomer and a (meth)acrylamide monomer, and a polymer hinder P that is soluble in an alkaline developing solution; and the outer coating comprises an infrared radiation absorbing compound and a polymer binder Q which is different from that in the inner coating. The imageable element is designed such that same is not only sensitive to radiation with a maximum wavelength of 700-1200 nm, but also has a good resistance to chemical solvents when used as a lithographic printing plate precursor, and same is not easily corroded and dissolved by printing chemicals during use, thus facilitating the prolonging of the service life of a lithographic printing plate.