To provide a recording medium capable of improving color development retention characteristics during high-temperature and high-humidity preservation and suppressing color development of a background.

The recording medium includes a recording layer that includes a coloring compound with electron-donating properties, and a color developer with electron acceptability. The color developer includes a compound represented by the following formula (1).

##STR00001## (wherein, in the formula (1), X.sup.1 represents a divalent group that has at least one benzene ring. Y.sup.11, Y.sup.12, Y.sup.13, and Y.sup.14 independently represent a monovalent group. Z.sup.11 and Z.sup.12 independently represent a hydrogen-bonding group.)

Disclosed is a heat-sensitive recording material containing at least an undercoat layer and a heat-sensitive recording layer in this order on a support, the undercoat layer containing hollow particles, a binder, and an inorganic pigment I, the heat-sensitive recording layer containing a leuco dye and a developer, wherein (A) the heat-sensitive recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N,N-bis-(3-methylphenyl)-isophthalic acid diamide as a stability improver, or (B) the heat-sensitive recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N,N-bis-(3-methylphenyl)-isophthalic acid diamide as the developer and contains a pigment with an oil absorption of 130 ml/100 g or less as an inorganic pigment II.

A color developer for a thermal recording layer includes: a compound of formula (I):

##STR00001##

; and an N-substituted amino acid derivative of formula (II): (R.sup.0X)Y(Z). The color developer is excellent in plasticizer resistance.

Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.

The invention relates to a heat-sensitive recording material. A heat-sensitive recording material, comprising a carrier substrate and a heat-sensitive, colour-forming layer that contains at least one colour former and at least one phenol-free colour developer, is characterised in that said at least one colour developer is a compound of formula (I) where Ar.sub.1 and Ar.sub.2 are a phenyl group and/or a C.sub.1-C.sub.4-alkyl substituted phenyl group. The invention also relates to a method for producing this heat-sensitive recording material and to the use, in a heat-sensitive recording material, of the colour developer of formula (I) that is present in said heat-sensitive, colour-forming layer.

##STR00001##

Provided are thermochromic color-memory composition and thermochromic color-memory microcapsule pigment encapsulating the same, the thermochromic color-memory composition including: (a) a component composed of an electron-donating color-developing organic compound; (b) a component composed of an electron-accepting compound; and (c) a component composed of an ester compound represented by the following Formula (1) as a reaction medium which controls color reaction between the components (a) and (b): ##STR00001##
(wherein, R represents an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms or a halogen atom; Y represents a hydrogen atom or a methyl group; and Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms or a halogen atom).

A thermosensitive recording layer forming liquid includes an electron-donating compound, an electron-accepting compound, and a solvent. A solubility of the electron-accepting compound to 100% ethanol at 20 C. is 5.0% by mass or less.

The present invention provides a heat-sensitive recording material having a high recording density, excellent plasticizer resistance in recorded portions, and excellent resistance to thermal background fogging in high-temperature environments. The heat-sensitive recording material includes a heat-sensitive recording layer containing a specific sulfonamide compound.

A thermosensitive recording medium is provided that is excellent in heat discoloration resistance in the blank portions and in bar code readability. It also has excellent water resistance and printing (recording) run-ability. The thermosensitive recording medium includes a support, a thermosensitive recording layer installed on the support, and a protective layer on the thermosensitive recording layer. The thermosensitive recording layer contains two kinds of electron accepting color developing agents, a sulfonic acid compound and a diphenyl sulfone compound. Both the thermosensitive recording layer and the protective layer contain crosslinking agents, and at least one, and preferably both, of the thermosensitive recording layer and the protective layer contain an ammonium zirconium carbonate as the crosslinking agent.

An object of the present invention is to provide a color developing composition which develops colors in a high density and does not significantly discolor when aged, a lithographic printing plate precursor which has excellent plate-inspecting properties by means of color development and is capable of maintaining strong color development even when aged after color development, a plate making method for a lithographic printing plate in which the lithographic printing plate precursor is used, and a new compound that can be preferably used as a color developer.

The color developing composition of the present invention includes a compound represented by Formula 1. The compound in the present invention is represented by Formula 1. In Formula 1, R.sup.1 represents a group in which an R.sup.1O bond is cleaved by heat or exposure to infrared rays.

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