Abstract: A light-permeable thermosensitive recording material having a light permeable support and a thermosensitive recording layer formed thereon and including a leuco dye, a color developer for the leuco dye, and a binder resin, wherein the developer is a compound represented by the following formula (1): wherein R1 represents an alkyl group having 4-16 carbon atoms or an aminoalkyl group having 4-16 carbon atoms.

Abstract: A thermally recording sheet which has high sensitivity in color development, satisfactory background heat resistance, and a satisfactory background color. The sheet contains a dihydroxydiphenylsulfone compound represented by general formula (1) as a color developer and a sulfonamide represented by general formula (2). In the formula, R1 and R2 each represents C1-8 alkyl, alkenyl, or halogeno; and a and b each is an integer of 0 to 3. In the formula, R3 represents C1-66 alkyl or electron-attracting group; and n is an integer of 0 to 2.

Abstract: A process for the manufacture of mixtures of fluoran compounds by the reaction of keto acids of formula (II) with a compound of formula (III) in the presence of a dehydrating condensation agent, wherein R1 and R2 independently represent hydrogen; an alkyl of 1-18 carbon, a secondary alkyl with respect to the carbon atom bonded to the nitrogen atom of 3-13 carbon atoms, a cycloalkyl of 4-8 carbon atoms or a phenyl, both of which may be substituted by at least one substituted selected from the group consisting of halogen atoms and alkyls having 1-4 carbon atoms, an aralkyl of 7-10 carbon atoms; or R1 and R2, together with the adjacent nitrogen atom from a heterocyclic ring; R3 is hydrogen, an alkyl of 1-4 carbon atoms, an alkoxy of 1-4 carbon atoms, a phenyl; a substituted phenyl or a halogen; R4 is an alkyl group of 1-18 carbon atoms, a carboxyalkyl of 1-18 carbon atoms, a carboxycycloalkyl of 4-8 carbon atoms, an alkylamino of 1-18 carbon atoms, a cycloalkylamino of 4-8 carbon atoms, a dialkylamino or dicyclo

Abstract: A thermosensitive recording composition includes a leuco dye, a color developer containing 4,4′-bisphenol S, and a sensitizer containing 4-acetylbiphenyl. A thermosensitive recording material has a support and a thermosensitive recording layer which is provided on the support and contains the above-mentioned thermosensitive recording composition.

Abstract: A monophase solid solution comprising a plurality of color formers selected from the group consisting essentially of the fluoran type, phthalide type, phenoxazine type, phenothiazine type, rhodamine lactam type, leuco-auramine type, triphenylmethane type, spiropyran type, benzoxazine type, quinazoline type of color formers and mixtures thereof, preferably wherein the color forming materials are selected from the fluoran and phthalide type of color former and mixtures thereof.

Abstract: The present invention is a novel thermally-responsive record material comprising a substrate having provided thereon in substantially contiguous relationship an electron donating dye precursor, an acidic developer material, a compound of the formula wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, alkoxy, aryl, aralkyl, aralkoxy, halogen, alkoxyalkoxy, and aralkoxyalkoxy; with the proviso that when R1, R2 and R3 are hydrogen, that R4 is not benzyloxyethoxy or alkyl-substituted benzyloxyethoxy; wherein R4 is independently selected from alkoxyalkyl, alkoxyalkoxy, and aralkoxyalkoxy, and a suitable binder therefor. In the context of the present invention the alkyl moieties in the alkyl, aralkyl, aralkoxy, alkoxyalkyl, alkoxyalkoxy and aralkoxyalkoxy preferably are eight carbons or less, and more preferably from one through four carbons. Substituents on aryl moieties in aryl, aralkyl, aralkoxy, and aralkoxyalkoxy groups can include hydrogen, alkyl, alkoxy and halogen.

Abstract: A thermal recording material which has high sensitivity in color development and a high whiteness of the background and is excellent in image retention and heat resistance. The thermal recording material contains a dihydroxydiphenylsulfon compound represented by general formula (1) as an organic color developer and 3-di-n-pentylamino-6-methyl-7-anilinofluoran as a colorless basic dye. (In the formula, R1 and R2 each represents C1-8 alkyl, alkenyl, or halogeno; and p and q each is an integer of 0 to 3.

Abstract: A transparent thermosensitive recording material capable of producing an image therein has a transparent support and a thermosensitive recording layer formed thereon, the recording layer containing a colorless or light-colored leuco dye, a color developer capable of inducing coloring formation in the leuco dye, and a binder resin. The image obtained in the recording material exhibits an absorbance of 3.0 or more at 610 nm when the image has a maximum transmission density, and the ratio of the absorbance at 700 nm to the absorbance at 610 nm is in a range of 0.1 to 0.3 within the region from a transmission density of the image of 1.0 to the maximum transmission density thereof.

Abstract: A thermal recording sheet which is satisfactory in sensitivity in color development, background heat resistance, and background color, is free from powdering, and has excellent image retention. The sheet comprises supporting and formed thereon a thermal color development layer containing as main components a colorless or light-colored basic dye and an organic color developer, and is characterized in that the thermal color development layer contains at least one dihydroxydiphenyl sulfone compound represented by general formula (1) as the organic color developer, and further contains either at least one saturated fatty acid monoamide represented by general formula (2) in an amount of 1.5 to 5 parts per part of the organic color developer or a combination of at least one saturated fatty acid monoamide represented by general formula (2) and at least one diphenyl sulfone derivative represented by the general formula (3).

Abstract: A recording medium comprises one or more of the compounds represented by General Formula (1) and/or General Formula (2): wherein R is any of a hydrogen atom, a substituted or unsubstituted alkokyl group, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted aryl group; wherein R1 is an alkyl group of 1 to 20 carbons, and R2, R3, R4, and R5 are respectively independently an alkyl group of 1 to 3 carbons.

Abstract: Disclosed are heat sensitive coatings and record materials that are environmentally resistant and therefore do not require a protective coating. One embodiment includes an environmentally resistant heat sensitive coating that includes an acrylate polymer of the formula: wherein R1 is a hydrogen or a methyl group, R2 is a hydrogen or a methyl group, and R3 is nitrile or chlorine or wherein, when c is 0, R4 is methyl, phenyl, or substituted phenyl, and when c is greater than 0, R4 is methyl, phenyl, substituted phenyl, halogen, nitrile or hydroxyl; m is greater than 1; n is greater than 1; b is greater than or equal to 0; and c is an integer from 0 to 38.

Abstract: A novel pressure sensitive record material suitable for use for high temperature reprographic equipment is disclosed comprising a sheet support carrying isolated droplets of an oil solution of chromogenic material, said isolated droplets being confined within respective pressure rupturable barriers, and, on the opposite surface of the same sheet or on a different sheet support, a coating of a acidic developer material effective to develop the color of the chromogenic material in solution on contact, wherein, the pressure rupturable barrier comprises microcapsules having a wall material formed from polymerization of melamine and formaldehyde, methylol melamine methylated methylol melamine, urea and formaldehyde, dimethylol urea or methylated dimethylol urea, with a copolymer of acrylic acid and alkyl acrylate; the oil solution comprises a blend of (i) a vegetable oil having a degree of unsaturation greater than 30% such as canola oil, soybean oil, corn oil, sunflower oil, or cottonseed oil with (ii) alkyl este

Abstract: The thermally sensitive recording medium having sufficient color developing density and develops sepia color or light brown color. The color difference a* value of developed image of said thermally sensitive recording medium regulated by JIS-Z-8729 is within the region of 0˜40 and b* value is within the region of 0˜55.

Abstract: The thermally sensitive recording medium having sufficient color developing density and develops navy blue or grayish blue color. The color difference L* value a* value and b* value of developed image of said thermally sensitive recording medium regulated by JIS-Z-8729 are within the regions of, A. L* value is 30˜50, a* value is −15˜0 and b* value is −30˜10, B. L* value is 30˜50, a* value is 0˜10 and b* value is −30˜0 or C. L* value is 30˜50, a* value is 10˜20 and b* value is −30˜15.

Abstract: A color former composition which is composed of a mixture of the color formers 3-diethylamino-6-methyl-7-(2′,4′-dimethylanilino)fluoran and 3-dibutylamino-6-methyl-7-anilinofluoran in defined amounts. Further compositions contain mixtures of color formers including one or both of these fluoran compounds and the color formers 3-dibutylamino-6-methyl-7-anilinofluoran and/or 3-diethylamino-6-methyl-7-(3′-methylanilino)fluoran. Microcapsules containing the color former compositions can be prepared from a composition which also contains an organic solvent and can be used to prepare a pressure sensitive or thermal recording material. The mixture of color formers can provide a higher concentration in various organic solvents and/or can be used with less expensive solvents.

Abstract: The present invention provides a recording material comprising a substrate, a heat-sensitive layer formed on the substrate by a coating liquid containing (1) microcapsules containing a colorless or light-colored electron-donative dye precursor and (2) a dispersion of solids comprising color developers, and a protective layer formed on the heat-sensitive layer, wherein the dispersion of solids comprising color developers is a dispersion prepared by co-dispersing at least three color developers including at least one solid color developer, preferably a water-soluble color developer, in the form of solid particles and at least one amorphous color developer together with a water-soluble polymer, and wherein the solid particles of the color developers contained in the dispersion have particle diameters in the range of from 0.3 to 0.5 .mu.m and the haze of the heat-sensitive recording material is 55% or less.

Abstract: A reversible thermosensitive recording material which includes a recording layer including an electron donating coloring agent and an electron accepting coloring developer and in which an image is reversibly formed and erased by appropriately heating and cooling the recording layer, wherein the recording material has an image density retention not less than about 60% when the recording material having an image is allowed to settle in a dry place at 50.degree. C. for 24 hours, a residual image density not greater than about 0.03 when the recording material having an image is heated at 110.degree. C. for 0.5 seconds to erase the image, and a residual image density after light irradiation not greater than about 0.04 when the recording material having an image is heated at 110.degree. C. for 0.5 seconds to erase the image after light of 5,000 lux is irradiated to the recording material for 100 hours.

Abstract: An internal phase solution for a coating of rupturable material for application to a base sheet to form a pressure-sensitive record material comprises one or more color-formers of which at least 90% are monoamino and/or diamino fluoran derivatives dissolved in a solvent comprising 80% to 100% of one or more vegetable and/or animal oils. Preferably the color-formers comprise only monoamino and/or diamino fluoran derivatives and the solvent comprises only one or more vegetable and/or animal oils. Dissolution of the color-formers in the solvent may be place at a temperature in the range 100.degree. C. to 135.degree. C. and micro-capsules containing such color-former solution may be formed by conventional coacervation processes below 70.degree. centigrade.

Abstract: Disclosed are a novel crystal form of the fluoran compound represented by formula (I) as characterised by specific X-ray powder diffraction pattern and melting range; process for the preparation of said novel crystal form and recording materials comprising the said crystal form.

Abstract: A thermosensitive reversible recording material capable of forming and holding clear colored images with a high contrast and capable of being repeatedly color-developed and color-erased many times, has a thermosensitive recording layer formed on substrate sheet and including (A) at least one reversibly color-developing and -erasing compound selected from those of the formulae (I), (II) and (III), and (B) at least one dye precursor compound of the formula (IV). ##STR1## R.sup.1 =naphyl or lower alkoxy-substituted phenyl group Y.sup.1, Y.sup.2 =--NHCO--, --SCONH--, --CONHCO--, etc., n, m, p=10 to 29, R.sup.2, R.sup.3, R.sup.4, R.sup.5 =C.sub.1 -C.sub.9 alkyl, C.sub.3 -C.sub.6 cycloalkyl or substituted or non-substituted phenyl group, R.sup.6, R.sup.7 =C.sub.1 -C.sub.6 alkyl or phenyl group.

Abstract: An improved thermally-responsive record material useful for bar coding is disclosed comprising a support having provided thereon in substantially contiguous relationship: a substantially colorless dye precursor comprising 2-anilino-3-methyl-6-dibutylaminofluoran; a sensitizer selected from the group consisting of 1,2-diphenoxyethane and 1,2-(4-methylphenoxy)ethane; an acidic developer material comprising bis-(3-allyl-4-hydroxyphenyl)sulfone which upon being heated reacts with said dye precursor to develop color; and a binder material. The improved thermally-responsive record material and bar code of the invention has a high print contrast signal; high dimensional stability in terms of low bar width growth degradation; a high percentage of successful decodes; and high contrast of the bar code with the background. The invention overcomes difficulties in past efforts to bring together a confluence of these characteristics in one coating formulation.

Abstract: Coverage of a chromogenic reaction product over a substrate is improved by incorporating a color developer in the substrate and coating the substrate with a color former to form a colored reaction product.

Abstract: A carbonless pressure-sensitive copying paper which uses a solvent free of an unpleasant odor and friendly to environments and is excellent in color formability and image keeping properties, the copying paper having a layer containing microcapsules enclosing a color former dissolved in a solvent, the solvent being a middle-length-chain triglyceride (MCT), the color former being an indolylazaphthalide compound or a fluoran compound having a trifluoromethylanilino group, the color former further containing a color former different in kind, the solvent further containing a specific fatty acid ester solvent in combination with the MCT, and the color developer being an inorganic color developer, preferably a simi-synthetic solid acid.

Abstract: The present invention provides a heat sensitive recording material comprising a substrate and a recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor, the recording material being characterized in that, the basic dye comprises an indolyldiazaphthalide derivative of the formula (1), and the color acceptor comprises a diphenyl sulfone derivative of the formula (2) and/or a benzanilide derivative of the formula (3) ##STR1## wherein R.sub.1 to R.sub.8 are defined in the specification.

Abstract: This invention provides a transparent thermal recording medium, in which the transparent thermal recording medium comprises: a thermal recording layer, which is provided on a transparent layer, consisting essentially of an electron-donating chromophoric compound, an electron-accepting compound and binder resin; and a further-provided protective layer having an approximately equal refractive index to the refractive index of the thermal recording layer, wherein the binder resin is a compound having a group selected from a hydroxyl group and a carboxyl group. The transparent thermal recording medium can be effectively used for a block copy film, on which an image is formed, for plate-making, particularly, in photogravure, offset printing and screen process printing, because the transparent thermal recording medium has a contrast of light transmission factors between a color-imaging portion and a non-imaging portion, in which the contrast is not less than 50% at a wavelength ranging from 370 nm to 450 nm.

Abstract: By using the fluoran compound represented by the following general formula (I); ##STR1## wherein R.sup.1 is alkyl containing 1 to 4 carbon atoms, R.sup.3 is alkyl containing 1 to 8 carbon atoms, R.sup.4 is hydrogen or alkyl containing 1 to 8 carbon atoms, or R.sup.3 and R.sup.4 may bond with each other to form a ring together with a N atom, R.sup.2 is alkyl containing 1 to 4 carbon atoms, and n denotes 0, 1 or 2, however, the substituents represented by R.sup.2 may be different with each other when n is 2, as a color former for color forming recording materials, recording materials which have excellent properties in whiteness of the background of the material under light and in photostability of color-formed images on the materials as well as in sufficient color forming capability of the material even after having exposed them to light, can be provided.

Abstract: An optical recording medium including a substrate having thereon a recording layer containing a dye precursor, a color developer reactable with the dye precursor to develop a color, and a light absorbent for converting light to heat, characterized in that the color developer is at least one compound of Formula (1):(R--NH (C.dbd.S) NH)n--Z (1)(wherein R denotes a substituted or unsubstituted alkyl, cycloalkyl, aryl, aralkyl, or alkenyl. n is an integer of 2 or more, and Z denotes a group having a valence of 2 or more.). The optical recording medium is superior in heat resistance and plasticizer resistance of the recorded image, heat resistance of background, water resistance, and moisture resistance.).

Abstract: A thermosensitive recording medium is disclosed which includes a support, and a thermosensitive color-developing layer formed on the support and containing a leuco dye having a melting point of at least 200.degree. C. and a color developer having a melting point of at least 180.degree..

Abstract: The invention describes a colour former mixture comprising(a) a compound of formula (1) and/or of formula (2) and/or of formula (3) and(b) a compound of formula (4),or a colour former mixture comprising at least two compounds of component (b).The colour former mixture is suitable for pressure- and particularly for heat-sensitive recording materials and has excellent storage ability and superior paper whiteness.

Abstract: A reversible heat-sensitive recording medium which includes at least a support and formed thereon a heat-sensitive recording layer including at least the following components: an electron-donating color-forming compound having a lactone ring, (b) an electron-accepting compound having a phenolic hydroxyl group, (c) at least one organic compound selected from compounds represented by formulae (I) to (V), and (d) a thermoplastic resin having an erasing action. The content of the thermoplastic resin having an erasing action is being from 15 to 70% by weight based on the total amount of components (a) to (d) Formulae (I) to (V) are as follows:R.sub.1 --CO--N(R.sub.2)R.sub.3 (I)R.sub.1 --CO--NH--R.sub.4 --NH--CO--R.sub.2 (II)R.sub.1 --CO--O--R.sub.2 (III)R.sub.1 --NH--CO--NH--R.sub.2 (IV)R.sub.1 --CO--R.sub.2 (V)wherein R.sub.1 represents an alkyl group, an aryl group, an alkenyl group, or a hydroxyalkyl group; R.sub.2 and R.sub.

Abstract: A novel thermally-responsive record material is disclosed comprising a support having provided thereon in substantially contiguous relationship an election donating dye precursor and a compound of the formula ##STR1##

Abstract: This invention generally relates to a reversible thermosensitive coloring composition and a thermosensitive recording medium using thereof which have high light-resisting characteristics, wherein coloring and decolorizing can be repeated suitably.

Abstract: A thermosensitive recording element having improved abrasion resistance, said element comprising (a) a support; (b) a first layer comprising an organic polymeric binder and either a substantially colorless electron donating dye precursor or an electron accepting compound or mixtures thereof; and (c) a second layer comprising an organic polymeric binder compatible with the binder in (b) and either a substantially colorless electron donating dye precursor or an electron accepting compound, wherein both dye precursor and electron accepting compound are present in the element and wherein the first layer is interposed between the support and second layer. These elements have wide application in the printing industry.

Abstract: The present invention provides a heat sensitive recording material comprising a substrate and a recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor, the recording material being characterized in that, the basic dye comprises at least one black-forming fluoran derivative and at least one phenothiazine derivative such as 3,7-bis(dimethylaminophenyl)-10-benzoylphenothiazine in an amount of 5 to 100 wt. % based on the fluoran derivative, and the color acceptor comprises a diphenyl sulfone derivative such as 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone.

Abstract: A heat-sensitive recording material suited for use in direct thermal imaging by means of an information-wise energized heating element, which recording material comprises on the same side of a support, called the heat-sensitive side, one or more binder layers containing a substantially light-insensitive metal salt in thermal working relationship with at least one organic reducing agent, characterized in that said recording material also comprises an acid-sensitive leuco dye transformable into dye by means of an acid-reacting compound serving as dye developer that stands in thermal working relationship with said leuco dye.

Abstract: Particularly advantageous and environmentally compatible recording material comprises, in microencapsulated form, at least one 3,1-benzoxazine color donor dissolved in a solvent, and is characterized in that the solvent consists of one or more natural oils and/or one or more esters of fatty acids on which natural oils are based, or comprises such oils and/or esters.

Abstract: It is provided with a thermal recording material having a support coated with a coating solution as a color developing layer. The color developing layer has a colorless dye precursor which is normally colorless or light-colored, and a developer which reacts with the dye precursor to cause color development thereof upon heating. The developer is a bisthiourea compound represented by, for example, a formula (A-2): ##STR1## and the thermal color developing layer contains no sensitizer. In the thermal recording materials of the present invention, substantially no color is developed at a temperature of 120.degree. C. while color development can be caused in response to heating with a thermal head or a laser beam. The developed color on the material can be erased upon contacting with alcoholic solvents, depending on the thiourea compound contained in the color developing layer. After erasure of the image, the material can be used again for recording with a thermal head or a laser beam.

Abstract: A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a leuco dye and a developer, formed on one side of the support, wherein the heat-sensitive recording layer contains an ultraviolet ray-absorbing agent, said ultraviolet ray-absorbing agent being a dimer ultraviolet ray-absorbing agent.

Abstract: The present invention provides a heat sensitive recording material comprising a recording layer formed on a substrate and containing a colorless or light-colored basic dye and a color acceptor, the material being characterized in that the basic dye is 3-(N-ethyl-N-p-tolyl)amino-6-methyl-7-p-toluidinofluoran, the color acceptor is bis(3-allyl-4-hydroxyphenyl)sulfone and/or 4-hydroxy-4'-isopropoxydiphenylsulfone.

Abstract: Disclosed is a thermal recording material having, on a support, a heat-sensitive coloring layer containing an electron-donating colorless dye, an isocyanate compound and an amino compound. The storage stability of the raw stock material as well as the color image stability of the material are excellent.

Abstract: A fingerprinting system comprising means capable of releasably retaining a liquid and a liquid composition releasably retained in said means, said liquid composition comprising a leuco color-former coupound, a dialkyl phthalate wherein the alkyl group contains 1-3 carbon atoms, a substrate for receiving fingerprints associated therewith, said substrate being coated on at least a portion of one surface thereof with a color developing substance comprising a phenol/aldehyde condensation product produced by the reaction together of an alkyl-substituted salicylic acid, an alkyl-substituted phenol, and an aldehyde, said condensation product having been reacted with a metal source.

Abstract: A thermosensitive recording element comprising a support having a Sheffield smoothness of less than 60, and at least one layer provided thereon wherein said layer comprises an organic polymeric binder, a substantially colorless electron donating dye precursor and an electron accepting compound capable of forming color by reacting with said dye precursor, wherein the binder, the electron accepting compound and the dye precursor have a particle size of less than about 3.mu..

Abstract: A thermosensitive recording material having a support and a thermosensitive coloring layer which is formed on the support and contains a leuco dye and a color developer capable of inducing color formation in the leuco dye upon application of heat thereto, with the color developer including one compound with an acid dissociation constant (pKa) of 7.0 or less in a mixed solvent of water and methanol with a volume ratio of 1:1.

Abstract: In a thermal recording sheet including an intermediate layer, and a thermal color developing layer containing a leuco dye type chromogenic component containing a leuco dye and an organic color developer as main ingredients and a metal chelate type chromogenic component containing an electron acceptor and an electron donor as main ingredients, stacked on a substrate, the intermediate layer contains a pigment having an oil absorption of 100 ml/100 g or less measured according to JIS K 5101, and the thermal color developing layer contains at least one of compounds of Formula (I) and Formula (II) as an organic color developer, a metal double salt of higher fatty acid having 16 to 35 carbon atoms as an electron acceptor, and a polyhydric hydroxy aromatic compound of Formula (III) as an electron donor, whereby providing a thermal recording sheet which is superior in dynamic sensitivity, background color, image stability such as oil resistance and plasticizer resistance, and print adaptability: ##STR1## wherein R is

Abstract: The improved two types of crystal modification of 2-m-toluidino-3-methyl-6-di-n-butylaminofluoran, as well as the crystalline toluene adduct thereof have high solubility in inner-phase solvent(s). Recording materials that use those compounds as electron donating color formers exhibit particularly good performance in various characteristics such as whiteness of the background, its storage stability, color rendition, sensitivity for color formation and image storage stability.

Abstract: An abrasion resistant thermosensitive recording element having high gloss, and improved abrasion resistance and process of preparing said element are described. The element comprises (a) a support, (b) a first layer comprising an organic polymeric binder and a substantially colorless electron donating dye precursor, and (c) a second layer comprising an organic polymeric binder compatible with the binder in (b), an electron accepting compound capable of forming color by reaction with said dye precursor, and a crosslinking agent, wherein the first layer is interposed between the support and the second layer. These elements have wide application in the printing industry.

Abstract: A thermal recording sheet superior in dynamic sensitivity, dot reproducibility, image quality and image storage stability, and having no trouble of turning yellow of the sheet caused by NOx gas.A thermal recording sheet comprising an intermediate layer and a thermal color developing layer provided in turn on a substrate, wherein the intermediate layer contains a pigment having an oil absorption (according to JIS K5101) of less than 80 ml/100 g, and a compound of the following general formula (I): ##STR1## wherein R denotes propyl, isopropyl, or n-butyl, and calcium carbonate are contained in the thermal color developing layer as an organic color developer and a pigment, respectively.

Abstract: The heat-sensitive recording material has on a base sheet a heat-sensitive recording layer which comprises a colorless or pale colored basic chromogenic material and a color developer. The recording layer comprises at least one fluoran derivative developing a black color and at least one azaphthalide derivative represented by the formula (I) as the basic chromogenic material, and at least one diphenylsulfone derivative represented by the formula (II) as the color developer. The azaphthalide derivative is used in an amount of 3 to 50 % by weight based on the amount of the fluoran derivative.

Abstract: The present invention provides a heat sensitive recording material comprising a recording layer formed on a substrate and containing a colorless or light-colored basic dye and a color acceptor, the material being characterized in that the basic dye is 3-diethylamino-7-[m-(trifluoromethyl)phenylamino]fluoran and/or 3-di-n-pentylamino-6-methyl-7-phenylaminofluoran, the color acceptor being 4,4'-dihydroxydiphenylsulfone.

Abstract: The invention relates to fluoran colour formers having improved fastness to sublimation and migration stability, to their preparation, to pressure-sensitive and heat-sensitive recording materials containing said compounds and to their preparation. The fluorans have the formula (I) as defined in claim 1.