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US 4,477,317 AGranted
Aluminum substrates useful for lithographic printing plates
AssigneePolychrome Corporation
InventorsSimon L. Chu, Eugene Golda, Jen-Chi Huang, Alan Wilkes
Life of this patent
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Abstract
A method for the production of aluminum substrates useful in the production of lithographic printing plates which comprises first mechanically graining at least one surface of an aluminum sheet to obtain a pumice grained surface of the aluminum sheet, and then electrolytically etching said grained surface with alternating current.
Claims5
A method of producing a lithographic printing plate which comprises:
- (a) pumice graining the smooth surface of an aluminum sheet;
- utilizing a wet slurry containing about 5.5 percent or more pumice alone or in combination with other abrasive materials
- (b) cleaning the surface of the resulting pumice grained aluminum sheet;
- (c) electrolytically graining said aluminum surface in an aqueous electrolyte whose solute consists essentially of hydrochloric acid, nitric acid, or combinations thereof at a time period of from about 0.15 to 2 minutes per square foot of aluminum surface being treated and at an alternating current density of from 2 to 100 amps per square decimeter wherein the electrolyte is maintained at from about 20 to 80 degrees C.;
- (d) rinsing said aluminum sheets with water;
- (e) drying said aluminum sheet;
- and
- (f) coating said aluminum sheet with a lithographically suitable photosensitive composition.
5 more elements
Dependencies are inferred from the claim text.