Process of flexographic printing utilizing an electrical field

Claim 1

In a printing process where a web or sheet to be printed moves through the nip of a plate cylinder and an opposed impression cylinder, the steps comprising: a. selecting an ink having a particular direction of migration under the influence of a directional electrical field; b. positioning on the plate cylinder a flexible relief printing plate having a resistivity lower than the resistivity to ground of the impression surface of the impression cylinder; c. positioning said impression cylinder in respect to said plate cylinder to ensure printinG contact between the printing surface of said flexible relief plate and a receiving web positioned to move through the nip between said plate cylinder and said impression cylinder; d. connecting a directional high voltage supply source to apply a directional electrical field between said plate cylinder and said impression cylinder, said directional field being applied in a direction which inhibits migration of said ink from the flexible relief plate towards the web; e. causing said web to move through said nip area at the same speed as the peripheral speed of said relief plate mounted on said plate cylinder whereby ink will transfer to the web by direct contact with the plate; and f. applying said selected printing ink to the printing plate while applying said directional electric field whereby ink transfers to the web by contact with the relief printing characters whilst ink is repressed in the surrounding lower areas of the plate.