GB1132216A - Multicolour printing - Google Patents

Abstract

1,132,216. Printing processes. INTERCHEMICAL CORP. 8 March, 1966 [7 June, 1965], No. 10111/66. Heading B6C. In a method of multicolour printing two or more differently coloured powder images are transferred sequentially by electrostatic forces from two or more different printing plates or cylinders to the surface of an offset member to form a multicolour image thereon and then the multicolour image is offset in a single transfer on to a desired substrate. The final transfer may be by electrostatic forces or by heating the substrate such that the powder sticks to its surface when contact is made. The printing plates may be of gravure or planographic form. As shown powder is supplied to electrically grounded gravure cylinders 10 from hoppers 13 by rotating brushes 14, excess powder being removed by doctor blades 15. The powders are charged by corona units 16 and 17, and transferred to charged offset cylinder 11 to form the multicolour image which is printed on to paper or other flexible sheeting 19 running over charged impression cylinder 12. Offset cylinder 11 may or may not be in contact with the material 19. Corona wires 18 and 20 may be used to charge the offset and impression cylinders. Transfer of the multicolour image to the material 19 may also be carried out by reversing the charge on the powder after transfer to the offset cylinder and grounding the impression cylinder. The impression cylinder and material 19 may be replaced by a bottle to which a potential is applied to transfer the powder image from the offset cylinder, adhesion of the image to the bottle being assisted by employing a pre-heated bottle.