Field of technology: Industrial Machinery and Processes
Patent granted on: Tue, 07 Dec 1999
A method of making a solvent based ink formulation which includes a thermochromic pigment, wherein the pigment being formed of microcapsules, includes drying a slurry that contains the pigment to a solids concentration between 80% and 95%, mixing the dried slurry in an appropriate mixing base, and adding any desired ink components to the base formulation. Each microcapsule contains a reversible thermochromic coloring material which exhibits a visible change in color between a first color state and a second color state in response to a change in temperature. Acceptable ink components include a gel vehicle, a free flow vehicle, a drying agent, a lithographic varnish, an ink wax, a polyester vehicle, a polyglycol solvent, a colloidal dispersion resin, water, and a defoamer.