LASER INDUCED IMAGE FORMING METHOD OF POSITIVE RADIATION SENSITIVE COMPOSITION CONTAINING LARGE QUANTITY OF CARBON BLACK

摘要

PROBLEM TO BE SOLVED: To provide a radiation sensitive planographic printing compsn. capable of forming images with IR rays. SOLUTION: This radiation sensitive planographic printing compsn. contains a positive radiation sensitive compd., a resin soluble in an aq. alkali and a relatively large quantity of carbon black. Such compsn. is applied on a metal base material and is subjected to image exposure by laser induction IR radiation. When this compsn. is developed by an aq. alkaline soln., a positive image is formed. The exposure is executed by a laser beam of about 800 to about 1100 nm in wavelength and about 50 to about 250 ml/cm<2> in energy level.