On press development of a diazo based printing plate

摘要

According to the present invention there is provided a method for making a lithographic printing plate comprising the steps of: (1) image-wise exposing an imaging element having on a support in the order given (i) a uniform ink-repellant layer comprising a hydrophilic binder cross-linked by means of a hydrolysed tetra-alkylorthosilicate and (ii) a photosensitive layer comprising a diazonium salt or a diazo resin; (2) and developing a thus obtained image-wise exposed imaging element by mounting it on a print cylinder of a printing press and supplying an aqueous dampening liquid and/or ink to said photosensitive layer. The present invention also provides a method for making multiple copies of an original comprising the steps of: (1) image-wise exposing an imaging element having on a support in the order given (i) a uniform ink-repellant layer comprising a hydrophilic binder cross-linked by means of a hydrolysed tetra-alkylorthosilicate and (ii) a photosensitive layer comprising a diazonium salt or a diazo resin; (2) mounting a thus obtained image-wise exposed imaging element without development, on a print cylinder of a printing press; (3) rotating said print cylinder while supplying an aqueous dampening liquid and/or supplying ink to said photosensitive layer of said imaging element and (4) transfering ink from said imaging element to a receiving element.