MANUFACTURE OF LITH PRINTING PLATE HAVING PICTURE FORMING ELEMENT INCLUDING PHOTOSENSITIVE ACID PRECURSOR

摘要

PROBLEM TO BE SOLVED: To provide an excellent lith printing plate by a dry process development method. SOLUTION: This method for obtaining the lith printing plate includes stages for (a) exposing a photosensitive image forming element including hydrophobic photosensitive layers contg. (i) a photosensitive precursor and (ii) a hydrophobic polymer binder on the hydrophilic surface of a base adjacently to the hydrophilic surface in compliance with images or information and (b) developing this exposed image forming element by stages for (i) laminating the uppermost layer of the image forming element on an image receiving layer before or after the exposure and (ii) stripping the image receiving layer from the hydrophilic surface of the base and thus transferring the hydrophobic photosensitive compsn. to the image receiving layer in compliance with the patterns. The hydrophobia photosensitive layers described above contain the nonionic photosensitive precursor of sulfonic acid or, in some cases, the nonionic photosensitive precursor of partially esterified phosphoric acid as the photosensitive acid precursor. The latter sulfonic acid or the precursor of phosphoric acid is incorporated into the layers in the absence of the acid-photosensitive compsn. of a low mol.wt. compd.