Electrorecording paper

Abstract

A recording paper having a color-developing layer containing a component capable of being colored or discolored by application of heat which has been made electroconductive by incorporation of an electro-conductive substance. When an electric current is applied to the color-developing layer, the recording paper selectively gives a visible record at a portion of the color-developing layer to which the electric current has been applied.

What we claim is: 
     
       1. An electrorecording paper having a color-developing layer containing a component capable of changing color in response to applied heat, said color-developing layer comprising a heat coloring component and an electroconductive substance, both of which are dispersed in the form of fine particles in a binder; said electroconductive substance being substantially light reflective, electron conductive and having a specific resistance not greater than 10 4  Ω cm and selected from the group consisting of cuprous iodide, tin dioxide.[.,.]. .Iadd.and .Iaddend.silver-iodide.[., and antimony.].; and said color-developing layer having a .[.surfacee.]. .Iadd.surface .Iaddend.resistivity of not greater than 10 7  Ω .[.cm..]. at a temperature of 20° C. and at a relative humidity of 65%; said layer being capable of recording by changing color in response to heat applied by means of an applied electric current. 
     
     
       2. An electrorecording paper according to claim 1, wherein said electroconductive substance is cuprous iodide. 
     
     
       3. An electrorecording paper according to claim 1, wherein said color-developing layer is in contact with a supporting member. 
     
     
       4. A recording paper according to claim 1, wherein the component capable of being colored by application of heat is composed of a leuco body of a triphenylmethane type dye or a leuco body of a fluoran type dye and a phenolic substance or an organic acid. 
     
     
       5. A recording paper according to claim 1, wherein the component capable of being colored by application of heat is composed of a metal salt and an organic spot reagent, which reacts with metal ions of said salt to form a visually observable reaction product, one of said two substances which is lower in melting point having a melting point of 70° to 150° C. 
     
     
       6. A recording paper according to claim 1, wherein the component capable of being colored by application of heat is a redox indicator.  .[.7. A recording paper according to claim 1, wherein the electroconductive substance is antimony-containing tin dioxide..]. .[.8. A recording paper according to claim 1, wherein the electroconductive substance is silica gel coated with antimony-containing tin dioxide..]. .[.9. A recording paper according to claim 1, wherein the electroconductive substance is 
     
     
        coated with a metal film..]. 10. A recording paper according to claim 3, wherein an electroconductive layer is disposed between the supporting 
     
     
        member and the color-developing layer. 11. A recording paper according to claim 10, wherein the electroconductive layer is a layer composed of a .[.support and a.]. metal, which has been deposited on the support by 
     
     
        vacuum evaporation. 12. A recording paper according to claim 10, wherein 
     
     
        the electroconductive layer is composed of cuprous iodide. 13. A recording paper according to claim 12, wherein the electroconductive layer composed of cuprous iodide .[. is a layer comprising a support and cuprous iodide, 
     
     
        which.].   has been deposited on the support by vacuum evaporation. 14. A recording paper according to claim 12, wherein the electroconductive layer composed of cuprous iodide is a layer comprising particles of cuprous 
     
     
        iodide which have been bonded by use of a binder. 15. A recording paper according to claim 10, wherein the electroconductive layer is a layer comprising carbon particles which have been bonded by use of a binder. 
     
     
            A recording paper according to claim 3, wherein the support is an 
     
     
        electroconductive material. 17. A recording paper according to claim 3, wherein a second color-developing layer formed by dispersing in a binder fine particles of a component capable of being colored by application of 
     
     
        heat is disposed between the color-developing layer and the support. 18. A recording paper according to claim 17, wherein an electroconductive layer is disposed between the second color-developing layer and the support.