Provided is a thermosensitive recording medium being excellent in oil resistance among various performances required for the thermosensitive recording medium, and being further excellent in heat resistance, plasticizer resistance, and printing (recording) run-ability.

That 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 contains at least two kinds of urea compounds. The two kinds of urea compounds comprise the first urea compound being represented by the following general formula 1, and the second urea compound being represented by the following general formula 2.

##STR00001##

wherein R.sup.1 represents a substituted or unsubstituted alkyl group, aralkyl group or aryl group, and R.sup.2 represents a hydrogen atom or an alkyl group,

##STR00002##

wherein R.sup.4 to R.sup.8 represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, and the like, and m represents an integer of 0 to 2.

Described are colour developers of formula (I)

Ar.sup.1—NH—CO—NH—C.sub.6H.sub.4—SO.sub.2—O—C.sub.6H.sub.4—NH—CO—NH—Ar.sup.2   (I),

a heat-sensitive recording material comprising a carrier substrate and also a heat-sensitive, colour-forming layer containing at least one colour former and at least one phenol-free colour developer, wherein the at least one colour developer is the compound of formula (I), and a method for producing this heat-sensitive recording material.

An object of the present invention is to provide a thermal recording material which is excellent in all of the following characteristics: plasticizer resistance, image stability against moisture and heat, the resistance to background fogging under moisture and heat, and the retention of color developing ability. Provided is a thermal recording material having, on a paper support, a heat-sensitive recording layer containing a colorless or light-colored dye precursor and a developer which reacts with the dye precursor on heating and converts the dye precursor to its colored form, the paper support containing 0.25 to 1.0% by mass of a neutral rosin sizing agent relative to the pulp solid content in combination with calcium carbonate and aluminum sulfate, the developer having a phenylureido moiety in its molecule.

The present invention relates to an N-(4-((4-(3-phenylureido)phenyl)sulfonyl)phenyl)benzenesulfonamide in the polymorphic form ω.sup.18.9, characterised by an x-ray powder diffractogram having the Bragg angles (2θ/CuK.sub.α) 10.9, 11.7, 14.6, 15.0, 15.8, 16.6, 17.6, 18.9, 19.4, 20.9, 21.2, 22.0, 23.3, 24.4, 24.7, 26.1, 27.4, 29.4, 34.2, or in the polymorphic form α.sup.21.2, characterised by an x-ray powder diffractogram having the Bragg angles (2θ/CuK.sub.α) 8.7, 9.8, 10.8, 13.2, 13.9, 14.9, 15.2, 16.0, 17.4, 17.7, 18.7, 20.4, 21.2, 21.6, 22.3, 23.0, 23.3, 23.9, 24.4, 25.0, 25.8, 26.6, 28.1, 28.9, 29.4, 30.1, 30.6, 31.8, 34.5, 35.3, 35.6, 36.9, a method for production thereof, use thereof as a colour developer in a heat-sensitive recording material, and a heat-sensitive recording material comprising N-(4-((4-(3-phenylureido)phenyl)sulfonyl)phenyl)benzenesulfonamide in the polymorphic form ω.sup.18.9 or in the polymorphic form α.sup.21.2.

A reversible recording medium according to an embodiment of the present disclosure includes a first recording layer to be colored in a first color, a second recording layer to be colored in a second color, the second color being different from the first color, and a first intermediate layer provided between the first recording layer and the second recording layer, the first intermediate layer including a plurality of layers respectively containing materials different from each other.

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 color laser markable article includes a color laser markable layer provided on a support, the laser markable layer including an infrared absorbing compound; a leuco-dye; and an acid generating compound, wherein the acid generating compound has a structure according to Formulae (I) or (II): ##STR00001##
wherein R1 and R3 independently represent an optionally substituted alkyl group, an optionally substituted (hetero)cyclic alkyl group, an optionally substituted (hetero)aryl group, an optionally substituted aralkyl group, an optionally substituted alkoxy group, an optionally substituted (hetero)cyclic alkoxy group, or an optionally substituted (hetero)aryl group; R2, R4 and R5 independently represent an optionally substituted alkyl, an optionally substituted (hetero)cyclic alkyl group or an optionally substituted aralkyl group; and R1 and R2, R4 and R5, R3 and R4, and R3 and R5 may represent the necessary atoms to form a ring.

Described are colour developers of formula (I) Ar.sup.1—SO.sub.2—NH—C.sub.6H.sub.4—SO.sub.2—C.sub.6H.sub.4—NH—CO—NH—Ar.sup.2 (I), a heat-sensitive recording material, comprising a carrier substrate and also a heat-sensitive, colour-forming layer comprising at least one colour former and at least one phenol-free colour developer, the at least one colour developer being the compound of formula (I), and a method for producing this heat-sensitive recording material.

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.2—O— or —O—SO.sub.2—). ##STR00001##

We disclose specialized direct thermal recording media that are both phenol-free and water-dispersible. The thermally responsive layer of such media includes a leuco dye and an acidic developer. To avoid image fade and image formation problems associated with certain demanding environmental storage conditions, the developer is not only phenol-free but also a derivative of N,N′-diphenylurea. The thermal recording medium also includes a base coat between the substrate and the thermally responsive layer, the base coat containing a non-water-soluble binder, and a top coat carried by the substrate such that the thermally responsive layer is between the top coat and the substrate.