This heat-sensitive recording material is configured to contain, as a color-developing compound, at least one compound represented by one of formulas (1)-(3): ##STR00001##

A thermosensitive recording medium comprising an undercoat layer provided on a substrate, and a thermosensitive recording layer containing a colorless or pale colored electron donating leuco dye and an electron accepting color developing agent provided on the undercoat layer, wherein the thermosensitive recording layer contains as the electron accepting color developing agent a urea compound represented by the following general formula (Formula 1)

##STR00001## (wherein X represents O or NH, R.sup.1 represents a hydrogen atom or SO.sub.2R.sup.3, R.sup.3 represents a substituted or unsubstituted alkyl group, aralkyl group or aryl group, R.sup.2 represents a hydrogen atom or an alkyl group, m represents an integer of 0 to 2, and n represents 0 or 1), and wherein the undercoat layer contains 50 to 95 weight % of a pigment by solid and 50 weight % or more of plastic hollow particles by solid with respect to the pigment.

The invention relates to a heat-sensitive recording material, comprising a carrier substrate and at least one heat-sensitive thermal reaction layer, which is applied to at least one side of the carrier substrate and contains at least one fluoran color former, at least one color developer, at least one melting aid, and optionally typical additives, such as lubricants, stabilizers (anti-aging agents), and/or pigments, characterized in that the color developer is dodecyl gallate and the melting aid is an ethylene bis fatty acid amide of formula (I), wherein R.sub.1 and R.sub.2 are CH.sub.3(CH.sub.2).sub.mCH.sub.2 with m=13 and/or 15. The invention further relates to a method for producing said recording material.

##STR00001##

To provide a heat-sensitive recording material which produces images with excellent resistance to water, while producing background with resistance to heat. A heat-sensitive recording material which is characterized by containing at least one compound represented by general formula (1) as a color-developing compound:

##STR00001##

wherein, R1-R5 each independently represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group or an arylamino group.

A heat-sensitive recording material including a web-shaped substrate having a front side and an opposite reverse side, and at least one heat-sensitive recording layer on either or both of the sides of the web-shaped substrate. The heat-sensitive recording layer contains at least one dye precursor at least one salicylic acid derivative as a (color) developer reactive with this at least one dye precursor, and polyvinylpyrrolidone as auxiliary component augmenting the (color) developer the at least one salicylic acid derivative is 3,5-di(-methylbenzyl)salicylic acid.

As a thermosensitive recording medium utilizes a coloring reaction between a colorless or pale colored electron donating leuco dye and an electron accepting color developing agent, a thermosensitive recording medium using an environment-friendly color developing agent is provided.

Provided is a thermosensitive recording medium having a thermosensitive recording layer comprising a colorless or pale colored electron donating leuco dye and an electron accepting color developing agent on a substrate, wherein the thermosensitive recording layer comprises a gluconolactone as the electron accepting color developing agent.

A heat-sensitive recording material includes a heat-sensitive recording layer containing a basic dye and a developer and provided on a supporting body, in which the developer is at least one type of an N-substituted amino acid derivative represented by the following General Formula: (RX).sub.mY(Z).sub.m . . . (1) (In Formula (1), R represents an alkyl group or an aryl group which may have a substituent. X is a group bonded to the N-terminus of Y, and represents OCO, SO.sub.2NHCO, NHCO, NHCS, or SO.sub.2. Y represents an amino acid residue or a peptide residue. Z represents a group bonded to the C-terminus of Y and represents an OH group or an OR group. When Y is an amino acid residue other than a cystine residue or when Y is a peptide residue not having a cystine residue, m=1, and when Y is a peptide residue having n cystine residues, m=n+1 and n is 1 or 2.)

A reversible recording medium according to an embodiment of the present disclosure includes: a recording layer including a coloring compound having an electron-donating property, a color developing/quenching agent having an electron-accepting property, a photothermal conversion agent, and a macromolecular material; and an ultraviolet absorbing layer provided on the recording layer, the macromolecular material including an organic material that has solubility of 20 wt % or more and 80 wt % or less at 25? C. or less and contains 0.5 wt % or less of chlorine atoms, fluorine atoms, and sulfur atoms in a molecule.

A heat-sensitive recording material includes a heat-sensitive recording layer containing a basic dye and a developer and provided on a supporting body, in which the developer is at least one type of an N-substituted amino acid derivative represented by the following General Formula:

(RX).sub.mY(Z).sub.m(1)

(In Formula (1), R represents an alkyl group or an aryl group which may have a substituent. X is a group bonded to the N-terminus of Y, and represents OCO, SO.sub.2NHCO, NHCO, NHCS, or SO.sub.2. Y represents an amino acid residue or a peptide residue. Z represents a group bonded to the C-terminus of Y and represents an OH group or an OR group. When Y is an amino acid residue other than a cystine residue or when Y is a peptide residue not having a cystine residue, m=1, and when Y is a peptide residue having n cystine residues, m=n+1 and n is 1 or 2.)

A heat-sensitive recording material including a web-shaped substrate having a front side and an opposite reverse side, and at least one heat-sensitive recording layer on either or both of the sides of the web-shaped substrate. The heat-sensitive recording layer contains a color acceptor having a combination at least consisting of one, two, three or more than three color acceptor (compounds) of formula (1) ##STR00001## where R is alkyl, and of at least one secondary color acceptor comprising lactic acid oligomers conforming to formula (3) ##STR00002##