| abstract |
According to the present invention there is provided a method for making lithographic printing plates including the following stepsa) preparing a heat mode imaging element having on a lithographic base with a hydrophilic surface a first layer including a polymer, soluble in an aqueous alkaline solution and a top layer on the same side of the lithographic base as the first layer which top layer is sensitive to IR-radiation 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 and the underlying areas of the first layer are dissolved and the unexposed areas of the first layer remain undissolved characterized in that said top layer includes an IR-dye in an amount between 1 and 100% by weight of the total amount of said IR-sensitive top layer selected from the group consisting of indoaniline dyes, cyanine dyes, merocyanine dyes, oxonol dyes, porphine derivatives, anthraquinone dyes, merostyryl dyes, pyrylium compounds, diphenyl and triphenyl azo compounds and squarylium derivatives. |