Scratch-off document having layers of different thermal conducitivity

Abstract

A scratch-off document includes a substrate and a toner covering; the toner covering including: a first layer of first toner particles on the substrate having a first and second thickness, wherein the first and second thicknesses are different; a second layer of second toner particles on the first layer of toner particles; and at least one additive in either the first or second layer for creating a thermal conductivity difference between the first and second layer, wherein a portion of the first layer having a greater thickness and a portion of the second toner layer in registration with the first layer of greater thickness is manually removable by a scratching action.

1 . A scratch-off document comprising:
 a substrate and a toner covering;   the toner covering comprising:   a first layer of first toner particles on the substrate having a first and second thickness, wherein the first and second thicknesses are different;   (ii) a second layer of second toner particles on the first layer of toner particles; and   (iii) at least one additive in either the first or second layer for creating a thermal conductivity difference between the first and second layer, wherein a portion of the first layer having a greater thickness and a portion of the second toner layer in registration with the first layer of greater thickness is manually removable by a scratching action.   
     
     
         2 . The scratch-off document as in  claim 1 , wherein the substrate includes hidden information. 
     
     
         3 . The scratch-off document as in  claim 1 , wherein the first toner particles or second toner particles include the at least one additive selected from the group consisting of air, calcium silicate, carbon, clay, diatomaceous earth, diatomite, foam glass, magnesia insulation, mica, nylon 6, paraffin wax, polypropylene, polystyrene, polystyrol, polyurethane foam, PTFE, PVC, rubber, sand, silicon aerogel, urethane foam, and vermiculite. 
     
     
         4 . The scratch-off document as in  claim 1 , wherein the second toner particles are optically opaque. 
     
     
         5 . The scratch-off document as in  claim 1 , wherein the first layer includes a mass laydown of the first toner particles in excess of 0.60 mg/cm 2 . 
     
     
         6 . The scratch-off document as in  claim 1 , wherein the second layer has the lower thermal conductivity second toner particles and is disposed uniformly at a mass laydown in excess of 1.0 mg/cm 2 . 
     
     
         7 . The scratch-off document as in  claim 1 , wherein the second layer has the lower thermal conductivity second toner particles disposed inversely relative to the first layer such that the regions of the hidden information have a mass laydownin excess of 1.0 mg/cm 2 . 
     
     
         8 . The scratch-off document as  claim 1 , wherein the first toner particles include individually or a combination of pigments and dyes. 
     
     
         9 . The scratch-off document as in  claim 1 , wherein the thermal conductivity of the first toner particles are in the range of 0.3 to 0.7 W/(m-° K) and the thermal conductivity of the second toner particles is less than or equal to 90% of the thermal conductivity of the first toner particles. 
     
     
         10 . The scratch-off document as in  claim 1 , wherein the thermal conductivity of the first toner particles are in the range of 0.3 to 0.7 W/(m-° K) and the thermal conductivity of the second toner particles is less than or equal to 70% of the thermal conductivity of the first toner particles. 
     
     
         11 . The scratch-off document as in  claim 1  wherein the first layer has the lower thermal conductivity first toner particles and is disposed non-uniformly over the substrate, such that this first toner layer is removable in regions where the mass lay-down of the first toner layer is in excess of 1.0 mg/cm 2 . 
     
     
         12 . The scratch-off document as in  claim 1 , wherein the thermal conductivity of the second toner particles are in the range of 0.3 to 0.7 W/(m-° K) and the thermal conductivity of the first toner particles is less than or equal to 90% of the thermal conductivity of the first toner particles. 
     
     
         13 . The scratch-off document as in  claim 1 , wherein the thermal conductivity of the second toner particles are in the range of 0.3 to 0.7 W/(m-° K) and the thermal conductivity of the first toner particles is less than or equal to 70% of the thermal conductivity of the first toner particles. 
     
     
         14 . The scratch-off document as in  claim 1  further comprising an indicia image on the substrate; wherein the regions of greater thickness are in registration with the printed indicia image.