| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an original plate for a planographic printing plate, which enables image recording using infrared laser scanning, which enables combination among on-machine developability, scumming resistance in printing and excellent printing resistance, and which is excellent in fine-line reproducibility, and a printing method for the planographic printing plate. <P>SOLUTION: In the original plate for the planographic printing plate, an image forming layer, which contains an infrared ray absorbent (A), an initiator (B) and a polymerizable compound (C), and which can be removed by using printing ink and/or dampening water, is provided on a substrate. In terms of the substrate, a surface area ratio ΔS<SP>50</SP>is in a range of 30-60%, and a degree a45<SP>50 (0.2-2)</SP>of steepness is in a range of 5-40%. The surface area ratio ΔS<SP>50</SP>is determined from an actual area S<SB>x</SB><SP>50</SP>and a geometrically measured area S<SB>0</SB><SP>50</SP>by the expression (1): ΔS<SP>50</SP>=(S<SB>x</SB><SP>50</SP>-S<SB>0</SB><SP>50</SP>)/S<SB>0</SB><SP>50</SP>×100 (%). The actual area S<SB>x</SB><SP>50</SP>is determined by an approximate three-point method from three-dimensional data which are obtained by 512×512-dot-measuring a square of a surface, having each side with a length of 50 μm, through the use of an atomic force microscope. The degree a45<SP>50 (0.2-2)</SP>of steepness is an area ratio of a part with a gradient of 45° or more in data which are obtained by extracting a component with a wavelength of ≥0.2 μm and ≤2 μm from the three-dimensional data. The planographic printing method is practiced by using the on-machine development of the original plate for the planographic printing plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
