摘要:
The present invention provides a concentrated dampening solution for use in a lithographic printing process having a pH between 3 and 6 and comprising a water-soluble organic solvent, a phosphate salt and a transparent pigment in an amount between 1 g/l and 30 g/l, characterized in that said concentrated dampening solution further contains a total concentration of citrate anions between 0.5 mmole and 25 mmole/l.
摘要:
A modulated writing light beam (18) having a wavelength to which an imaging element (33) is sensitive and a reference light beam (46) having a wavelength to which the imaging element (33) is insensitive are generated and simultaneously directed to a moving optical device (22) to cause the writing light beam (18) to scan across the surface of the imaging element (33) in a first scanning direction (C) and the reference light beam (46) to scan across the surface of a light detecting element (50) in the first scanning direction (C) to generate signals indicative of the position of the writing light beam (18) on the surface of the imaging element (33). The writing light beam (18) is modulated and the imaging element (33) is moved in a second scanning direction (B) in response to the signals generated by the light detecting element (50). Thereafter the exposed imaging element (33) is processed to prepare a lithographic printing plate. The invention is applicable to both positive and negative imaging working systems.
摘要:
The present invention provides a method for lithographic printing comprising the following steps:preparing a lithographic printing plate according to the silver salt diffusion transfer process by (1) image-wise exposing an imaging element comprising on a support a photosensitive layer comprising a silver halide emulsion and an image receiving layer containing physical development nuclei in water permeable relationship with said emulsion layer, (2) developing said imaging element in the presence of developing agent(s) and silver halide solvent(s) using an alkaline processing liquid and (3), if said emulsion layer is overlying said image receiving layer, removing the layers overlying said image receiving layer,mounting said lithographic printing plate to a lithographic printing press, andprinting while supplying to said lithographic printing plate a dampening solution and a printing ink characterized in that the dampening solution as used on the printing plate contains less than 1.0 g/l of a transparent pigment with an average grain diameter of less than 0.1 .mu.m and at least 0.35 g/l of a clay incorporating an inorganic polyphosphate peptiser.