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

Claim 2

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 compound, a halogen-substituted aliphatic carboxylic compound, an aliphatic carboxylic 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.

Claim 3

The reversible thermosensitive coloring composition 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 aliphatic carboxylic 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; (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--, and R 10 represents a straight chain or branched chain alkyl group or alkenyl group having 12 or more carbon atoms.