Porous structure of the lithographic printing plate (PP) has most significant influence on the quality of the imprints. This study presents the results of application of EIS in characterization of printing plates' porous structures and their changes during the processing. Two common PP types – thermal sensitive (digital plates) and light sensitive (conventional plates), were investigated. The influence of processing solution's working age on topographical changes and associated change in impedance spectra of PPs are investigated and discussed. The equivalent electrical circuit models reproducing the observed EIS spectra are proposed. Based on these models two mechanisms responsible for PP performance degradation due to the processing are identified and discussed.

Grafička tehnologija,Kemija,Fizika