The positive die photosensitive constituent, positive die photosensitive planographic printing edition and the positive image formation mannered null below-mentioned

摘要

PROBLEM TO BE SOLVED: To provide a positive type photosensitive composition having high sensitivity to light in the near IR region, excellent in contrast between image and non-image areas and therefore ensuring wide development conditions as a positive type photosensitive composition comprising a photothermal converting material and an alkali-soluble resin and to provide a positive type photosensitive planographic printing plate and a positive image forming method using the printing plate.;SOLUTION: The positive type photosensitive composition contains (A) a photothermal converting material which absorbs light of a light source for imagewise exposure and converts it into heat, (B) a novolak resin, (C) a surfactant and (D) a ferrocene compound. The positive type photosensitive planographic printing plate is obtained by forming a layer of the positive type photosensitive composition on the surface of a base. In the positive image forming method, the positive type photosensitive planographic printing plate is subjected to scanning exposure with laser light in the wavelength range of 650-1,300 nm and developed in an alkali developing solution.;COPYRIGHT: (C)2002,JPO