IR‐empfindliche Schichten zur Herstellung von Offset‐Druckplatten

IR sensitive layers for manufacturing of offset printing plates For the formulation of IR sensitive compositions for offset printing plates, two different modes are known to use the energy stored after the absorption of an IR photon in the excited state of an absorbing molecule. A physical mode is based on generated heat after internal crossing of the excited state. In contrast, a chemical mode proceeds via formation of reactive intermediates as consequence of the IR absorption. Such species can be generated either by thermal decomposition of a thermolabile component of the composition or by interaction between an excited state molecule of the IR absorber and a ground state molecule of a suited reaction partner. The heat generated by internal crossing is already used in commercial available offset printing plates by means of coalescence or ablation processes. Single electron transfer reactions are processes of choice for a chemical deactivation of the excited state of IR absorbers. For a high efficiency of such processes, certain thermodynamic and kinetic prerequisites must be fullfilled. Electron deficient molecules such as onium salts are well suited as reaction partners for excited states of IR absorbers.