PURPOSE: To eliminate dangerousness in developing processing and to improve the processing performance of a waste water by developing a printing plate having a photosensitive layer containing a diazo resin and a specific alkali soluble high molecular compound with an alkali developer having pH less than a specific value after image exposure.
CONSTITUTION: A photosensitive planographic printing plate has the photosensitive layer containing the diazo resin and the alkali soluble or alkali swelling high molecular compound of a copolymer having a structural unit induced from a formula and a structural unit induced from (metha)acrylic long chain alkyl ester as the structural components on a supporting body. After image exposure, the photosensitive planographic printing plate is developed with the water based alkali developer having <pH 12 and containing substantially no organic solvent. In the formula R1 represents hydrogen atom or methyl group, (n) represents integers of 3-10. As a result, the dangerousness such as the cauterization of hand or the loss of eyesight in handling is evaded and waste water processing performance in disposal are improved.
MATSUMURA TOMOYUKI
NOGUCHI KAZUO
MURATA MASAHISA
TOSHIMITSU ERIKO
TSUJI SHIGEO
MITSUBISHI CHEM CORP