The invention relates to a color developer of formula (I), (Ar.sup.1SO.sub.2NH-)m-Y(NHC(O)NHSO.sub.2Ar.sub.2)n (I), wherein Ar.sup.1 is an unsubstituted or substituted aromatic moiety, Ar.sup.2 is an unsubstituted or substituted phenyl moiety, Y is at least an (m+n)-times substituted benzene group or naphthalene group, and Y is substituted in such a way that at least one Ar.sub.2SO.sub.2NHC(O)NH group is in ortho-position with respect to at least one Ar.sup.1SO.sub.2NH group. The invention further relates to a heat-sensitive recording material, comprising a carrier substrate and a heat-sensitive color-forming layer, which contains at least one color former and at least one phenol-free color developer, the at least one color developer being the compound of formula (I). The invention further relates to a method for producing said heat-sensitive recording material.

An object is to provide a thermosensitive recording material and a laminate which are excellent in color development sensitivity, which cause less color development in a blank area even at a high temperature, which are also favorable in storage stability of a print area, and which are excellent in contrast between a blank area and a print area. A thermosensitive recording material in which a thermosensitive recording layer is provided on a support, wherein the thermosensitive recording layer contains a specific diphenylsulfone compound and an analog compound thereof at a specific ratio. A laminate in which a thermosensitive recording layer is provided on a support, wherein the thermosensitive recording layer contains a specific diphenylsulfone compound and an analog compound thereof at a specific ratio.

Developing agent precursors and laser markable compositions including such developing agent precursors.

A reversible recording medium according to an embodiment of the present disclosure is a reversible recording medium that includes recording layers and heat-insulating layers that are alternately stacked, in which the recording layers each include a reversible heat-sensitive color developing composition and a first light-heat converting agent. In this reversible recording medium, the recording layers are different from each other in a developing color of their respective reversible heat-sensitive color developing compositions and are different from each other in an absorption wavelength of their respective first light-heat converting agents. This reversible recording medium further includes a heat-generating layer that includes a second light-heat converting agent having an absorption wavelength that is different from the absorption wavelength of the first light-heat converting agent included in each of the recording layers.

A color-forming composition is useful to provide a printout image in an imaged lithographic printing plate precursor. This color-forming composition includes (a) an acid generator; (b) a tetraaryl borate; (c) an acid-sensitive dye precursor; and (d) a compound having the following Structure (I):

##STR00001##

wherein n is 1, 2, 3, or 4; R independently represents a monovalent substituent or the atoms necessary to form a fused ring if n is at least 2, and at least one R substituent is an electron-withdrawing group. The color-forming composition is included within a negative-working radiation-sensitive imageable layer along with a free radically polymerizable component and a radiation absorber such as an infrared radiation absorber.

An object of the present invention is to provide a recording material or a recording sheet using, as a color-developing agent, a non-phenol-based compound good in color developing performance and the like. A compound represented by the following formula (I) is used as the color-developing agent:

##STR00001##

(wherein X represents CH.sub.2 or the like; R.sup.1 to R.sup.3 each independently represent a hydrogen atom, a halogen atom or the like; n1 and n3 each independently represent any integer of 1 to 5; two groups represented by R.sup.3 adjacent to each other on a benzene ring optionally bond to each other to form an optionally substituted 6-membered ring; and n2 represents any integer of 1 to 4).

A recording material and a recording sheet having better color-developing performance, storage stability, etc. A recording material which contains (A) at least one color former, (B) at least one compound selected from the group including compounds represented by the following formula (I), and (C) at least one compound selected from the group including compounds represented by the following formula (II)

(wherein R.sup.1 to R.sup.3 each represent a halogen atom, a nitro group, a C.sub.1 to C.sub.6 alkyl group, a C.sub.1 to C.sub.6 alkoxy group, a C.sub.2 to C.sub.6 alkenyl group or a C.sub.1 to C.sub.6 haloalkyl group, n1 and n3 each independently represent any integer of 0 to 5, n2 represents any integer of 0 to 4, and X represents SO.sub.2O or OSO.sub.2).

##STR00001##

The invention relates to a color developer of formula (I), (Ar.sup.1SO.sub.2NH)m-Y(NHC(O)NHSO.sub.2Ar.sub.2)n (I), wherein Ar.sup.1 is an unsubstituted or substituted aromatic moiety, Ar.sup.2 is an unsubstituted or substituted phenyl moiety, Y is at least an (m+n)-times substituted benzene group or naphthalene group, and Y is substituted in such a way that at least one Ar.sub.2SO.sub.2NHC(O)NH group is in ortho-position with respect to at least one Ar.sup.1SO.sub.2NH group. The invention further relates to a heat-sensitive recording material, comprising a carrier substrate and a heat-sensitive color-forming layer, which contains at least one color former and at least one phenol-free color developer, the at least one color developer being the compound of formula (I). The invention further relates to a method for producing said heat-sensitive recording material.

The purpose of the present disclosure is to improve the sensitivity of 4,4-dihydroxydiphenylsulfone, which is a developer, in a heat-sensitive recording material. The present disclosure provides a heat-sensitive recording material that uses at least one selected from 1,2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane, benzyloxynaphthalene, and oxalic acid di-p-methylbenzyl ester as a sensitizer for 4,4-dihydroxydiphenylsulfone, and further includes benzoin as a sensitization aid.

A reversible recording medium of an embodiment of the present disclosure includes a support base and a recording layer. The recording layer is provided on the support base and reversibly changes between a recorded state and a deleted state. A chroma difference C* between the support base and the recording layer satisfies the relational expression (1) where an absorption spectrum in a visible region of the recording layer in the deleted state and an absorption spectrum in a visible region of the support base are each denoted by L*a*b*.