CPC B41N 1/083 (2013.01) [C22C 21/00 (2013.01); C22F 1/04 (2013.01)] | 17 Claims |
1. A method for manufacturing a lithographic printing plate support or a printing plate for the waterless offset printing, wherein the method comprises utilizing an aluminium alloy strip which has a rolled-in surface topography on at least one strip surface, wherein the surface of the aluminium alloy strip has a mean peak number RPc measured perpendicular to the rolling direction of the aluminium alloy strip of ≤50 cm−1, wherein a first cutting line c1=+0.25 μm and a second cutting line c2=−0.25 μm were selected as cutting lines for the RPc measurement and the mean peak number RPc is determined from an optical areal measurement of three measuring areas of at least 4.5 mm×4.5 mm with a confocal microscope having a lateral measuring point spacing of 1.6 μm or less, wherein within the measuring areas the arithmetic mean value of the profile parameter RPc perpendicular to the rolling direction is calculated from the profile sections of the areal measurement available per measuring area perpendicular to the rolling direction and the arithmetic mean is calculated from the three measuring areas for the parameter, wherein the measurement data preparation is carried out by a shape adjustment with a second order polynomial (F-filter) and a Gaussian filter with λc=250 μm as waviness filter without filtering of the fine roughness.
|