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METHOD OF IMPROVING INK TRANSFER FROM AN OFFSET BLANKET IN LITHO-GRAPHIC PRINTING

IP.com Disclosure Number: IPCOM000023228D
Original Publication Date: 1977-Feb-28
Included in the Prior Art Database: 2004-Mar-29

Publishing Venue

Xerox Disclosure Journal

Abstract

One method of achieving complete ink transfer from an offset blanket to paper in lithographic printing is to coat the blanket first with a release agent of lower cohesive strength. A method of improving transfer of ink of higher cohesive strength from a master to a coated offset blanket is to temporarily heat the ink to reduce its cohesive strength. The ink on the master should be heated just prior to trans-fer to the offset blanket by microwave radiation. Since the ink contains usually about l0%-30%water as emulsion, the radiation energy is effectively and selectively coupled to the ink via the water or molecules containing the hydroxyl group. By the time the ink image on the offset blanket comes into contact with paper at transfer, the ink has cooled sufficiently to regain most of its cohesive strength, Com-plete transfer is then assured by the layer of release agent of lower cohesive strength.