Thermal paper with preprinted indicia
View Patent ↗Thermosensitive recording materials such as thermal paper have printed indicia of high quality on the back thereof printed on a backcoating. This backcoating also incorporates an optically variable compound which provides a security feature.
1. A thermosensitive recording material comprising a base sheet, optionally a base coating, a thermosensitive coating on one surface of said base sheet or the surface of said base coating when present, and a backcoating on the surface of the base sheet opposite the thermosensitive coating, wherein said backcoating incorporates an optically variable thermochromic compound and said backcoating additionally having thereon a flexographic, lithographic, wet-offset printed, gravure, or inkjet printed image.
2. A thermosensitive recording material comprising a base sheet, optionally a base coating, a thermosensitive coating on one surface of said base sheet or the surface of said base coating when present, and a backcoating on the surface of the base sheet opposite the thermosensitive coating, wherein said backcoating incorporates an optically variable thermochromic compound and said backcoating additionally having thereon a flexographic, lithographic, wet-offset printed, gravure, or inkjet printed visible image.
3. A recording material as in claim 2 , wherein the optically variable thermochromic compound provides a color change that can be sensed by a naked human eye when heated to a temperature of 21° C. to 51° C.
4. A recording material as in claim 2 , wherein the thermochromic compound comprises from 1 wt % to 50 wt % of the backcoating based on a total solids.
5. A recording material as in claim 2 , wherein the thermochromic compound is microencapsulated.
6. A recording material as in claim 2 , wherein the thermochromic compound changes color when cooled to a temperature below 12° C.
7. A recording material according to claim 2 , wherein the backcoating has a thickness of 0.05-2.0 mils.
8. A recording material according to claim 2 , wherein the printed image is a visible flexographic printed image.
9. A recording material according to claim 2 , wherein the visible printed image comprises a pigment of carbon black, cadmium, primrose, cobalt oxide, or nickel oxide.
10. A recording material according to claim 9 , wherein the pigment is carbon black.
11. A recording material according to claim 9 , wherein the pigment is cadmium.
12. A recording material according to claim 9 , wherein the pigment is primrose.
13. A recording material according to claim 9 , wherein the pigment is cobalt oxide.
14. A recording material according to claim 9 , wherein the pigment is nickel oxide.
15. A recording material according to claim 1 ,wherein the printed image is a flexographic printed image.
16. A recording material according to claim 1 , wherein the printed image comprises a pigment of carbon black, cadmium, primrose, cobalt oxide, or nickel oxide.