METHOD OF ENHANCING TRANSFER OF COAGULATED COLLOID ONTO A SUBSTRATE DURING ELECTROCOAGULATION PRINTING

摘要

An improved electrocoagulation printing method comprising the steps of (a) providing a positive electrode formed of an electrolytically inert metal and having a continuous passivated surface moving at substantially constant speed along a predetermined path, the passivated surface defining a positive electrode active surface; (b) forming on the positive electrode active surface a plurality of dots of colored, coagulated colloid representative of a desired image, by electrocoagulation of an electrolytically coagulable colloid present in an electrocoagulation printing ink comprising a liquid colloidal dispersion containing the electrolytically coagulable colloid, a dispersing medium, a soluble electrolyte and a coloring agent; and (c) bringing a substrate into contact with the dots of colored, coagulated colloid to cause transfer of the colored, coagulated colloid from the positive electrode active surface onto the substrate and thereby imprint the substrate with the image. The improvement resides in maintaining the positive electrode active surface and the ink at a temperature of about 35.degree.C to about 60.degree.C to increase the viscosity of the coagulated colloid in step (b) so that the dots of colored, coagulated colloid remain coherent during their transfer in step (c), thereby enabling the colored, coagulated colloid to be substantially completely transferred onto the substrate in step (c).