Reversible thermosensitive coloring recording medium, recording method, and image display apparatus using the recording medium

Claim 2

A reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition comprising (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, a halogen substituted aliphatic carboxylic acid compound, an aliphatic carboxylic acid compound, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 3

The reversible thermosensitive coloring recording medium as claimed in claim 1, wherein said electron-acceptor compound is selected from the group consisting of: (a) an organic phosphoric acid compound with formula (I): R.sub.1 --PO(OH).sub.2 (I) wherein R 1 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (b) an α-hydroxycarboxylic acid compound with formula (II): R.sub.2 --CH(OH)--COOH (II) wherein R 1 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (c) a halogen-substituted aliphatic carboxylic acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said halogen being bonded to at least one carbon atom at α-position or β-position of said aliphatic carboxylic acid compound; (d) an aliphatic carboxylic acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, including an oxo group with at least one carbon at α-position, β-position or γ-position of said α-hydroxycarboxylic acid compound constituting said oxo group; (e) an aliphatic carboxylic acid compound of formula (III) ##STR21## wherein R 3 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and p is an integer of 1 or 2; (f) an aliphatic carboxylic acid compound of formula (IV): ##STR22## wherein R 4 , R 5 and R 6 each represent hydrogen, an alkyl group, or an alkenyl group, at least one of R 4 , R 5 or R 6 being a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and p is an integer of 1 or 2; (g) an aliphatic carboxylic acid compound of formula (V): ##STR23## wherein R 7 and R 8 each represent hydrogen, an alkyl group, or an alkenyl group, at least one of R 7 or R 8 being a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (h) an aliphatic carboxylic acid compound of formula (VI): ##STR24## wherein R 9 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, n is an integer of 0 or 1, m is an integer of 1, 2 or 3, and when n is zero, m is 2 or 3, while when n is 1, m is 1 or 2; and (i) a phenolic compound with formula (VII): ##STR25## wherein Y represents --S--, --O--, --CONH--, --COO--, R 10 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms and n is 1 or 3.

Claim 4

The reversible thermosensitive coloring recording medium as claimed in claim 1, wherein said reversible thermosensitive coloring recording layer further comprises a binder resin.

Claim 5

The reversible thermosensitive coloring recording medium as claimed in claim 1, further comprising a protective layer comprising a polymeric material which is provided on said reversible thermosensitive coloring recording layer.

Claim 6

The reversible thermosensitive coloring recording medium as claimed in claim 4, further comprising an undercoat layer comprising a polymeric material between said support and said reversible thermosensitive coloring recording layer.

Claim 7

The reversible thermosensitive coloring recording medium as claimed in claim 1, further comprising an undercoat layer comprising a polymeric material between said support and said reversible thermosensitive coloring recording layer.

Claim 8

The reversible thermosensitive coloring recording medium as claimed in claim 6, wherein said undercoat layer further comprises microballoons and serves as a heat-insulating layer.

Claim 9

The reversible thermosensitive coloring recording medium as claimed in claim 1, wherein said support is made of a heat-insulating material.

Claim 10

The reversible thermosensitive coloring recording medium as claimed in claim 1, further comprising a resin layer formed on said reversible thermosensitive coloring recording layer, said resin layer making said reversible thermosensitive layer transparent, and wherein said support is a transparent support.

Claim 11

The reversible thermosensitive coloring recording medium as claimed in claim 1, further comprising a magnetic layer interposed between said support and said reversible thermosensitive coloring recording layer.

Claim 12

The reversible thermosensitive coloring recording medium as claimed 1, wherein said reversible thermosensitive coloring recording layer further comprises a light-to-heat converting material.

Claim 13

The reversible thermosensitive coloring recording medium as claimed in claim 1, further comprising a light-to-heat converting material in contact with or near said reversible thermosensitive coloring recording layer.

Claim 14

The reversible thermosensitive coloring recording medium as claimed in claim 1, wherein said reversible thermosensitive coloring recording layer comprises a plurality of reversible thermosensitive coloring recording sections capable of producing different colors.

Claim 15

A reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition comprising (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, a halogen substituted aliphatic carboxylic acid compound, an aliphatic carboxylic acid compound, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 16

A reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition comprising (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, a halogen substituted aliphatic carboxylic acid compound, an aliphatic carboxylic acid compound, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 17

The reversible thermosensitive coloring display medium as claimed in claim 14, wherein said electron-acceptor compound is selected from the group consisting of: (a) an organic phosphoric acid compound with formula (I): R.sub.1 --PO(OH).sub.2 (I) wherein R 1 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (b) an α-hydroxycarboxylic acid compound with formula (II): R.sub.2 --CH(OH)--COOH (II) wherein R 1 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (c) a halogen-substituted aliphatic carboxylic acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said halogen being bonded to at least one carbon atom at α-position or β-position of said aliphatic carboxylic acid compound; (d) an aliphatic carboxylic acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, including an oxo group with at least one carbon at α-position, β-position or γ-position of said α-hydroxycarboxylic acid compound constituting said oxo group; (e) an aliphatic carboxylic acid compound of formula (III): ##STR26## wherein R 3 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and p is an integer of 1 or 2; (f) an aliphatic carboxylic acid compound of formula (IV): ##STR27## wherein R 4 , R 5 and R 6 each represent hydrogen, an alkyl group, or an alkenyl group, at least one of R 4 , R 5 or R 6 being a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and p is an integer of 1 or 2; (g) an aliphatic carboxylic acid compound of formula (V): ##STR28## wherein R 7 and R 8 each represent hydrogen, an alkyl group, or an alkenyl group, at least one of R 7 or R 8 being a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms; (h) an aliphatic carboxylic acid compound of formula (VI): ##STR29## wherein R 9 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, n is an integer of 0 or 1, m is an integer of 1, 2 or 3, and when n is zero, m is 2 or 3, while when n is 1, m is 1 or 2; and (i) a phenolic compound with formula (VII): ##STR30## wherein Y represents --S--, --O--, --CONH--, --COO--, R 10 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms and n is 1 or 3.

Claim 18

The reversible thermosensitive coloring display medium as claimed in claim 14, wherein said reversible thermosensitive coloring recording layer further comprises a binder resin.

Claim 19

The reversible thermosensitive coloring display medium as claimed in claim 14, further comprising a protective layer comprising a polymeric material which is provided on said reversible thermosensitive coloring recording layer.

Claim 20

The reversible thermosensitive coloring display medium as claimed in claim 17, further comprising an undercoat layer comprising a polymeric material between said support and said reversible thermosensitive coloring recording layer.

Claim 21

The reversible thermosensitive coloring display medium as claimed in claim 14, further comprising an undercoat layer comprising a polymeric material between said support and said reversible thermosensitive coloring recording layer.

Claim 22

The reversible thermosensitive coloring display medium as claimed in claim 19, wherein said undercoat layer further comprises microballoons and serves as a heat-insulating layer.

Claim 23

The reversible thermosensitive coloring display medium as claimed in claim 14, wherein said support is made of a heat-insulating material.

Claim 24

The reversible thermosensitive coloring display medium as claimed in claim 14, further comprising a resin layer formed on said reversible thermosensitive coloring recording layer, said resin layer making said reversible thermosensitive layer transparent, and wherein said support is a transparent support.

Claim 25

The reversible thermosensitive coloring display medium as claimed in claim 14, further comprising a magnetic layer interposed between said support and said reversible thermosensitive coloring recording layer.

Claim 26

The reversible thermosensitive coloring display medium as claimed in claim 14, wherein said reversible thermosensitive coloring recording layer further comprises a light-to-heat converting material.

Claim 27

The reversible thermosensitive coloring display medium as claimed in claim 14, further comprising a light-to-heat converting material in contact with or near said reversible thermosensitive coloring recording layer.

Claim 28

The reversible thermosensitive coloring display medium as claimed in claim 14, wherein said reversible thermosensitive coloring recording layer comprises a plurality of reversible thermosensitive coloring recording sections capable of producing different colors.

Claim 29

A reversible thermosensitive coloring recording method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 30

A reversible thermosensitive coloring recording method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 31

A reversible thermosensitive coloring display method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition, and said electron-donor coloring compound and said electron-acceptor compound at the eutectic temperature thereof, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 32

A reversible thermosensitive coloring display method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor compound selected from the group consisting of an organic phosphoric acid compound, an α-hydroxycarboxylic acid, and a phenolic compound, each having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition, and said electron-donor coloring compound and said electron-acceptor compound at the eutectic temperature thereof, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 33

A reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 34

A reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 35

A reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 36

A reversible thermosensitive coloring display medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis.

Claim 37

A reversible thermosensitive coloring recording method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 38

A reversible thermosensitive coloring recording method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition at the eutectic temperature thereof, and said electron-donor coloring compound and said electron-acceptor compound, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring recording medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 39

A reversible thermosensitive coloring display method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group of alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition, and said electron-donor coloring compound and said electron-acceptor compound at the eutectic temperature thereof, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring display medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.

Claim 40

A reversible thermosensitive coloring display method of reversibly forming a colored image or decolorizing the same in a reversible thermosensitive coloring recording medium comprising a support and a reversible thermosensitive coloring recording layer formed thereon, said reversible thermosensitive coloring recording layer comprising a reversible thermosensitive coloring composition consisting essentially of (i) an electron-donor coloring compound and (ii) an electron-acceptor organophosphoric acid compound having a straight chain or branched chain alkyl group of alkenyl group having 12 or more carbon atoms, said electron-donor coloring compound and said electron-acceptor compound being capable of reacting to induce color formation in said reversible thermosensitive coloring composition, and said electron-donor coloring compound and said electron-acceptor compound at the eutectic temperature thereof, when fused and colored in a mixed state, with application of heat thereto, followed by rapidly cooling said fused mixture, exhibiting an exothermic peak in a temperature elevation process in a differential scanning calorific analysis or in a differential thermal analysis, comprising the steps of: applying heat to the surface of said reversible thermosensitive coloring display medium to a coloring temperature above said eutectic temperature of said electron-donor coloring compound and said electron-acceptor compound to obtain a colored state; and applying heat to the surface of said reversible thermosensitive coloring recording medium to a decolorizing temperature which is lower than said coloring temperature to obtain a decolorized state.