| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of forming a printing plate which can hold the sensitivity of a photo-polymerizable layer even though an image is directly writing on the printing plate through laser exposure, and which is excellent in processing stability during development and in ink adhesion during printing. SOLUTION: A printing plate master 3 which has a photosensitive layer containing a compound having an ethylene-unsaturated bond and a photo-polymerization initiator on a hydrophilic surface of a substrate is laid at its substrate side on a member having a plurality of suction holes 1, and a transparent sheet 4 having a size greater than that of the master 4 is superposed on the photosensitive layer side of the master 3. With this arrangement, an image is exposed which ventilation is made through the suction holes 1, and is then developed so as to obtain a printing plate. In this case, the transparent sheet 4 has a permeability of 40% at a light wavelength used in the image exposure, and a smooth star value of higher than 50mmHg at 25deg.C and at 50%RH on the surface making contact with the photo-sensitive layer. |
