Digital printing process

摘要

A printing process is disclosed which comprises directing droplets of an ink onto an intermediate transfer member to form an ink image, the ink including an organic polymeric resin and a coloring agent in an aqueous carrier, and the transfer member having a hydrophobic outer surface so that each ink droplet in the ink image spreads on impinging upon the intermediate transfer member to form an ink film. The ink is dried while the ink image is being transported by the intermediate transfer member by evaporating the aqueous carrier from the ink image to leave a residue film of resin and coloring agent. The residue film is then transferred to a substrate. The chemical compositions of the ink and of the surface of the intermediate transfer member are selected such that attractive intermolecular forces between molecules in the outer skin of each droplet and on the surface of the intermediate transfer member counteract the tendency of the ink film produced by each droplet to bead under the action of the surface tension of the aqueous carrier, without causing each droplet to spread by wetting the surface of the intermediate transfer member.

主权项

1. A printing process which comprises directing droplets of an ink onto an intermediate transfer member to form an ink image at an image forming station, the intermediate transfer member comprising lateral formations on the side edges of the member, the lateral formations being compatible with guiding channels positioned at least at the image forming station to maintain the transfer member taut in its width ways direction, the ink including an organic polymeric resin and a coloring agent in an aqueous carrier, and the transfer member having a hydrophobic outer surface, each ink droplet in the ink image spreading on impinging upon the intermediate transfer member to form an ink film; drying the ink while the ink image is being transported by the intermediate transfer member by evaporating the aqueous carrier from the ink image to leave a residue film of resin and coloring agent; and transferring the residue film to a substrate, wherein the chemical compositions of the ink and of the surface of the intermediate transfer member are selected such that attractive intermolecular forces between molecules in the outer surface of each droplet and on the surface of the intermediate transfer member counteract the tendency of the ink film produced by each droplet to bead under the action of the surface tension of the aqueous carrier, without causing each droplet to spread by wetting the surface of the intermediate transfer member.