A reversible recording medium of an embodiment of the disclosure includes a support base, and a recording layer provided on the support base and reversibly changing between a recorded state and a deleted state. The recording layer includes a photothermal conversion material including one or more of a compound having a phthalocyanine skeleton, a compound having a squarylium skeleton, a compound having a cyanine skeleton including, in a molecule, one or both of a counter ion of SbF.sub.6, PF.sub.6, BF.sub.4, ClO.sub.4, CF.sub.3SO.sub.3 and (CF.sub.3SO.sub.3).sub.2N and a methine chain containing a five-membered ring or a six-membered ring, and an inorganic compound; a coloring compound having an electron-donating property; and a color developing/quenching agent having an electron-accepting property and including at least one salicylic acid compound represented by the general formula (1) and including a linear hydrocarbon group having 25 to 34 carbon atoms via a linking group containing an amide moiety.

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##

The present invention relates to an N,N-diarylurea derivative represented by the following general formula (1) and a method for producing the same. In addition, the present invention relates to a thermosensitive recording material in which a thermosensitive recording layer including a basic dye which is colorless or lightly colored at room temperature and a developer capable of developing color upon contact with the basic dye by heating is provided on a base sheet, wherein the developer is the N,N-diarylurea derivative represented by the following general formula (1):

##STR00001##

(wherein R2 is an alkyl group, an aralkyl group, or an aryl group; and Al is a hydrogen atom or an alkyl group).

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.

Provided is a thermosensitive recording medium including a support, and a thermosensitive recording layer provided over at least one surface of the support and containing a leuco dye and a developer, wherein the developer includes 4-hydroxy-4-benzyloxydiphenylsulfone and a diphenylsulfone compound represented by general formula (1), and wherein a content of the diphenylsulfone compound represented by general formula (1) is less than 3.0 parts by mass relative to 1.0 part by mass of the 4-hydroxy-4-benzyloxydiphenylsulfone.

The invention relates to a heat-sensitive recording material, comprising a supporting substrate and a heat-sensitive color-forming layer, which contains at least one color former and at least one phenol-free color developer, characterized in that the at least one color developer is a compound of formula (I), wherein Ar is an aryl residue, a heteroaryl residue, or a benzyl residue and Y is an aryl residue, a heteroaryl residue, a benzyl residue, an aryloxy residue, a heteroaryloxy residue, a benzyloxy residue, an arylamino residue, a heteroarylamino residue, or a benzylamino residue. The invention further relates to a method for producing said heat-sensitive recording material. ##STR00001##

The disclosure provides a novel crystal form of N-(2-(3-phenylureido)phenyl)benzenesulfonamide, which is crystalline modification thereof specified by an X-ray diffraction diagram having peaks at diffraction angles (20.1) of 23.60, 20.80, 12.24 and 13.80 in a powder X-ray diffractometry using Cu-K ray.

The invention relates to a self-adhesive, heat-sensitive recording material, comprising a carrier substrate, a heat-sensitive, color-forming layer that is applied on one side of the carrier substrate and contains at least a non-phenolic color developer in and at least one color former, a siliconized layer on the upper side of the heat-sensitive, color-forming layer that is applied on the carrier substrate, as well as an adhesive layer on the side of the carrier substrate facing away from the heat-sensitive, color-forming layer.

An object of the invention is to provide a recording material and recording sheet having excellent color-developing performance, storage stability, etc. A recording material having good color-developing performance and storage stability may be obtained by using a specific compound having a benzhydrol skeleton as an additive in a recording material employing color development through a reaction between a color former and a color-developing agent.

A heat-sensitive recording material suitable for offset printing, having a web-shaped substrate, having a front side and a reverse side opposite the front side, a heat-sensitive recording layer disposed at least on one of the two sides of the web-shaped substrate having at least one dye precursor and at least one (color) developer reactive with the dye precursor. The heat-sensitive recording layer has particles including an organic surface whose extent in the direction of the thickness of web-shaped substrate and heat-sensitive recording layer is greater than the thickness of the heat-sensitive recording layer.