Polyvinyl chloride film local isometric heat treatment for hidden 3D printing on polymer packaging

Abstract

ABSTRACTA method of 3D embossed printing is proposed where both point and line images can be printed on rigid polyvinyl chloride (PVC) shrink films without any consumables, such as paints, primers, dampening solutions, or washes. Embossed lettering and symbols on packaging are intended for people with poor vision, but capable of tactile marking recognition and reading Braille. This 3D printing is based on reversible deformation and stress relaxation in anisotropic glassy polymers by local isometric heat treatment of thermoplastic films under pressure. Films can be protected from counterfeiting by hidden markings due to time separation of information recording onto the film and displaying this information for visual or tactile reading. The results quantify the rate of internal stress relaxation in PVC shrink films at various stages of 3D printing, including tactile sign formation conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43046.