Patent ID: 6475630
Filing Date: 2002-11-05
Classification: B41N,Y10T

Abstract:
A planographic printing plate, a surface of an aluminum plate being a support element of said planographic printing plate having been subjected to preliminarily polishing mechanically by at least 0.1 &mgr;m, chemical etching treatment by at least 0.1 &mgr;m, electrochemically surface-roughening, and anodic oxidation, wherein a surface structure of said aluminum plate is characterized in that:(a) an area (S) for a graphic formed by a reference straight line drawn from a top of a third highest mountain of a two-dimensional roughness curve downwardly by 1 &mgr;m and a roughness curve above the reference straight line is 30 &mgr;m2&lE;S&lE;150 &mgr;m2; (b) an average roughness Ra of average lines is 0.15 &mgr;m&lE;Ra&lE;0.60 &mgr;m; (c) a relationship between the average roughness Ra of average lines and a height Rp of a center line is Rp&lE;6Ra; (d) a relationship between a maximum height Rmax and the average roughness Ra of average lines is Rmax&lE;12Ra; and (e) a surface area difference is between 20% and 70%.