Bimetallic lithographic printing plates
AssigneeHowson-Algraphy Limited
InventorLeonard James Watkinson
Life of this patent
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Abstract
A sheet material for bimetallic printing plate production comprises a base metal layer, a thin bimetallic layer comprising lithographically different metals, and a barrier layer between the base metal layer and the bimetallic layer. The barrier layer may be an anodic layer on the base metal layer or a film or sheet of suitable plastics material. The layers are laminated together and the barrier layer prevents corrosion by electrochemical action and by the decomposition products of the constituents of the adhesives used. Additionally, in the case where the barrier layer is of plastics material, the plate is resistant to fragmentation during printing. The sheet material may be produced in continuous lengths and results in printing plates which are relatively light in weight.
Claims11
A sheet material suitable for the production of a bimetallic lithographic printing plate, which sheet material comprises
- a. a self-supporting film or sheet of inert electrically insulating plastics material,
- b. a base metal layer laminated to one surface of the film or sheet, and
- c. a bimetallic layer laminated to the other surface of the film or sheet, one metal of the bimetallic layer being an ink-receptive metal and the other metal of the bimetallic layer being a water-receptive metal, said film or sheet forming a continuous electrically insulating spacing barrier layer between the base metal layer and the bimetallic layer whereby said lithographic sheet material is characterized by improved resistance to electrochemical corrosion during storage.
Dependencies are inferred from the claim text.