A method for making positive working printing plates from a heat mode sensitive imaging element

摘要

According to the present invention there is provided a method for making lithographic printing plates including the following steps a) preparing a heat mode imaging element consisting of a lithographic base with a hydrophilic surface and a top layer which top layer is sensitive to IR-radiation, comprises a polymer, soluble in an aqueous alkaline solution and is unpenetrable for an alkaline developer containing SiO2 as silicates; b) exposing imagewise said heat mode imaging element to IR-radiation; c) developing said imagewise exposed heat mode imaging element with said alkaline developer so that the exposed areas of the top layer are dissolved and the unexposed areas of the top layer remain undissolved characterized in that said top layer includes an IR-absorbing pigment and 3,4,5-trimethoxybenzoic acid or a benzofenone.