Radiation-sensitive element, especially useful as lithographic printing plate precursor, comprising carrier coated with layer containing infrared absorbers or diazo compound and layer containing diazo resin

摘要

New radiation-sensitive elements (A) comprise (a) an optionally pretreated carrier, (b) a first layer (applied to (a)) containing polymeric binder(s) soluble or swellable in aqueous media and a radiation-sensitive component selected from infrared absorbers (I) and compounds (II) containing a diazo (=N2) group (including derivatives or mixtures) and (c) a covering layer, containing at least one negatively working diazo resin (III). Independent claims are included for: (1) the preparation of (A), by (i) applying a first coating solution, comprising organic solvent(s), the polymeric binder(s) and (I) or (II), to the carrier, (ii) drying, (iii) applying a second coating solution, comprising organic solvent(s) and (III), and (iv) drying; and (2) an image forming method, involving imagewise exposure of (A) with radiation of wavelength 650-1300 nm if the radiation-sensitive component is (I) or 300-450 nm if the radiation-sensitive component is (II), followed by treating with an aqueous alkaline developer of pH at least 11.5 (preferably 12-14).