To provide a process capable of stably and easily producing a plate material for a negative type planographic printing plate which is directly formable from digital data of a computer, etc., and has excellent stability in preservation and high sensitivity by recording the use of a solid laser for radiating IR rays and semiconductor laser.
The production of the negative paleographic printing plate including a stage of applying a photosensitive layer coating material contg. a novolak resin, acid generating agent, acid crosslinkable compd. and IR absorbent on a base is executed in this process. In such a case, the pH of the coating liquid is adjusted to a range of 3 to 7 in preparing the coating liquid. The pH of the coating liquid refers to the value obtd. by adding 10 wt.% pure water to the coating liquid and measuring the pH with an ordinary glass pH electrode.
NAKANISHI HARUO
KIKUCHI TAKASHI
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