Abstract: A litho strip for use as an offset printing plate is described which has a composition of 0.05-0.25% Si, 0.30-0.40% Fe, 0.10-0.30% Mg, max. 0.05% Mn, and max. 0.04% Cu. The strip is produced from a continuous cast ingot of the above composition which is hot rolled to a thickness of up to 2-7 mm. The residual resistance ratio of the hot rolled strip is RR=10-20. The cold rolling is carried out with or without intermediate annealing, wherein the degree of rolling reduction after intermediate annealing is >60%. The further processing up to the EC roughening takes place with the microstructure adjusted in the rolling process at <100° C. The litho strip is characterized by a high thermal stability, a good roughening behavior in the EC processes, and a high reverse bending fatigue strength perpendicular to the rolling direction.

Abstract: The invention relates to a printing plate substrate made of a rolled and embossed aluminum strip, wherein the surface has depressions with an average diameter of <25 &mgr;m and an aspect ratio of <1.5 (ratio length/width relative to the transport direction of the strip). The number of depressions is >2,500/mm2. The invention also relates to a method of making an aluminum printing plate substrate, wherein the surface of the aluminum strip is roughened using rollers. The surfaces of the rollers have microscopically small, stochastically distributed, dome-shaped projections. In cross-sectional view, the rollers have a round ridge-shaped roughness profile. The invention is also directed to an offset printing plate, wherein a printing plate substrate is produced with the method and provided with an anodically deposited oxide layer. A light-sensitive hydrophobic, oleophilic layer is deposited on the oxide layer.

Abstract: The invention is directed toward a base material for aluminum offset printing plates having improved heat stability comprising an aluminum alloy consisting of from about 0.2 to about 0.6% by weight of iron, less than about 0.25% by weight silicon and copper combined, from about 0.1 to about 0.3% by weight manganese and the remainder being aluminum and trace production impurities, said base material further characterized as containing secondary precipitates in the form of phases of the Al Mn Si: Al Fe: Al Mn type which bear a ratio to one another of from about 1:1:2 to about 1:1:3, the mean particle size being from about 0.25 to about 0.010 micron with a maximum particle size of less than about 0.3 micron and further containing a precipitation structure with a degree of dispersion of less than about 50 phases per cubic micron and a process for producing such material. The sheet material according to this invention may be uniformly roughened in either HCl or HNO.sub.

Abstract: A litho strip for use as an offset printing plate is described which has a composition of 0.05-0.25% Si, 0.30-0.40% Fe, 0.10-0.30% Mg, max. 0.05% Mn, and max. 0.04% Cu. The strip is produced from a continuous cast ingot of the above composition which is hot rolled to a thickness of up to 2-7 mm. The residual resistance ratio of the hot rolled strip is RR=10-20. The cold rolling is carried out with or without intermediate annealing, wherein the degree of rolling reduction after intermediate annealing is >60%. The further processing up to the EC roughening takes place with the microstructure adjusted in the rolling process at <100° C. The litho strip is characterized by a high thermal stability, a good roughening behavior in the EC processes, and a high reverse bending fatigue strength perpendicular to the rolling direction.