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US 4,054,094 AGranted
Laser production of lithographic printing plates
AssigneeE. I. Du Pont de Nemours and Company
InventorsJack R. Caddell, Harvey H. Hoehn
Life of this patent
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Abstract
The use of a laser beam to etch the surface of a printing plate made from a polymer composition on a metal or plastic base and a thin top coating of a hard hydrophilic material produces a lithographic printing plate capable of accepting ink in the etched region and accepting water in the unetched regions.
Claims1
A process for making a lithographic printing plate, the imaging portion of which comprises a metallic surface which comprises the steps of:
- a. providing a plate comprising an aluminum base, a thin coating of an organic polymeric composition comprising materials selected from the group conisting of polyester, polymethyl methacrylate and polyoxymethylene, disposed on one surface of said aluminum base, and a thin coating of poly silicic acid, disposed on the exposed surface of said organic polymeric composition;
- b. removing a portion of the polysilicic acid and the organic polymeric composition to expose the aluminum base by subjecting the plate to a focused laser beam having an intensity sufficient to burn through the polysilicic acid and organic polymeric composition without substantially melting said aluminum base;
- and
- c. varying in a controlled manner, the point at which the laser beam impinges on said plate so that a predetermined pattern can be engraved on said plate.
1 more element
Dependencies are inferred from the claim text.