Planographic printing plate, non-woven cloth roller, and method and apparatus for preliminarily polishing a metal plate for printing plate

摘要

The present invention provides a planographic printing plate capable of ensuring improvement of productivity and stability of a small dot net portion due to improvement of adhesion. There is provided a planographic printing plate, characterized in that a surface of an aluminum plate (12) being a support element of the planographic printing plate has been subjected to preliminarily polishing mechanically by at least 0.1 mu m; chemical etching treatment by at least 0.1 mu m; electrochemically surface-roughening; and anodic oxidation, and for a surface structure of the aluminum plate: (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 mu m and a roughness curve upper than the reference straight line is 30 mu m<2> ≤ S ≤ 150 mu m<2>; (b) an average roughness Ra of average lines is 0.15 mu m ≤ Ra ≤ 0.60 mu m; (c) a relationship between the average roughness Ra of average lines and a height Rp of a center line is Rp ≤ 6Ra; (d) a relationship between a maximum height Rmax and the average roughness Ra of average lines is Rmax ≤ 12Ra; and (e) a surface area difference is between 20% and 70%.