| 摘要 |
PROBLEM TO BE SOLVED: To provide a supporting member having excellent performance in the printing durability when used as a printing block, particularly in anti-fouling property with respect to dot-like stains by specifying the relative load length and the surface average roughness (Ra) of a specific cutting level of a load curve obtained by a stylus type surface roughness shape measuring device. SOLUTION: As a supporting member for a planography block, capable of contacting with a photosensitive layer closely and retaining water excellently, while preventing generation of dot-like stains in printing, one processes so as to have a 90% or more relative load length at a position lower than the cutting level 50% of the load curve obtained by a needle contact type surface roughness shape measuring device by 1.5μm, and a 0.3 to 0.8μm surface average roughness (Ra) is used. In the production of such a supporting member, after successively applied with mechanical roughing, a chemical etching treatment, and a death mat treatment, the surface of an aluminum plate is applied with an electrochemical roughing in an acidic electrolyte mainly containing nitric acid or hydrochloric acid. Then, chemical etching, death mat treatment, and anodic axidation treatment are applied successively. |
