Abstract: There are described novel fluorescein dye compounds and imaging members and imaging methods utilizing the compounds. The fluorescein dye compounds exhibit a first color when in the crystalline form and a second color, different from the first color, when in the liquid, amorphous form.

Abstract: A recording material and a recording sheet free from surface fogging and excellent in dynamic coloring sensitivity, wet heat resistance, heat resistance, light resistance, plasticizer resistance, and water resistance. A recording material comprising a composition containing at least one kind of a compound (1) and at least one kind of a compound (2) and/or at least one kind of a compound (3), and a recording sheet having a recording layer formed from the recording material. Compound (1), Compound (2), Compound (3) (in the formulae, R1, R2, R6, R7, R11, R12 indicate hydrogen atom or alkyl radical, a1-a3 integer of 1-6, n1-n3 0, 1 or 2, m1, m4 and m7 0, 1, 2, or 3. R3, R4, R8, R9, R13, R14 indicate alkyl radical or the like, m2, m3, m5, m6, m8, and m9 0, 1 or 2, Y1-Y3 Co or NRCO (R indicates hydrogen atom or the like)).

Abstract: Disclosed is a molecule containing a first chromophore that exhibits a first absorption maximum above 700 nm and a second chromophore that exhibits a second absorption maximum different from the first absorption maximum, wherein the absorption of the first and second chromophores are substantially independent of each other. The molecule exhibits improved stability.

Abstract: The present invention discloses a heat-sensitive recording material comprising a thermal recording layer disposed on a substrate which layer contains at least a diazonium salt compound and a coupler which has a coupling reaction with the diazonium salt compound to develop a color, wherein the thermal recording layer microcapsules, which encapsulate the diazonium salt compound, an aromatic carboxylate represented by the following general formula (I) and an aromatic carboxylate represented by the following general formula (II).

Abstract: A process for adjusting the energy of an imaging laser for imaging of a thermally imageable element including the steps of: (a) providing an imaging unit having a non-imaging laser and an imaging laser, the non-imaging laser having a light detector which is in communication with the imaging laser, (b) contacting a receiver element with the thermally imageable element in the imaging unit, wherein the receiver element comprises a light attenuating layer having a front surface and a back surface; (c) actuating the non-imaging laser to expose the thermally imageable element and the receiver element to an amount of light energy sufficient for the light detector to detect the amount of light reflected from the thermally imageable element and light attenuating layer of the receiver element; and (d) actuating the imaging laser to focus the imaging laser in order to expose the thermally imageable element to an amount of light energy sufficient for imaging the thermally imageable element

Abstract: The present invention provides a diazonium salt represented by the following general formula (1) wherein R1 represents a branched alkyl group; R2 and R3 separately represent an alkyl group and may bond to each other to form a ring; R4, R5, and R6 separately represent a hydrogen atom, an alkyl group, or an aryl group and R4 and R5 may bond to each other to form a ring; and X− represents an anion and a heat-sensitive recording material comprising a heat-sensitive recording layer including the diazonium salt and a coupler.

Abstract: A heat-sensitive recording material which has a heat-sensitive recording layer formed on a surface of a substrate, the recording layer comprising a basic chromogenic dye precursor and a developer, wherein as the developer, there is used a mixture comprising 5 to 95 wt % of 2,2-dimethyl-1,3-bis(4-hydroxybenzoyloxy)propane and 95 to 5 wt % of 4,4′-hydroxydiphenyl sulfone.

Abstract: An image recording medium comprising a light and heat change material capable of recording an image with laser beam is described, characterized in that therein are incorporated a heat generator having no absorption at a wavelength of 500 nm or more which undergoes exothermic decomposition to amplify heat generation when acted upon by heat and a compound which undergoes thermochemical reaction to show an absorption change at a wavelength of from 360 nm to 900 nm.

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: Disclosed is a reversible thermosensible recording medium comprising a base board, a rewritable thermosensible recording layer which contains a liquid crystal compound showing a cholesteric liquid crystal phase and is provided on the base board, and a protective layer which is provided on the recording layer and contains an ultraviolet curing resin and at least one of a lubricant and an ultraviolet stabilizer.

Abstract: Dual shell microcapsule aggregate particles and copy materials coated therewith, such aggregate particles having inner shells surrounding chromogenic nucleus material, and outer shells encompassing multiple such inner shells to form aggregate particles thereof. The inner shells are derived from polar pre-polymer compositions. The outer shells are derived from complex colloids such as gelatin and gelatin derivatives. The outer shell material causes agglomeration of the inner shells into aggregate particles, thus increasing the sizes of the particles without increasing the sizes of the respective inner-shell microcapsules which contain the chromogenic material.

Abstract: According to the present invention, a coloring property-improved novel leuco dye which can develop color by heat even with single molecule without requiring excess developer can be obtained, and an image recording medium having high sensitivity and excellent resolution effected by including the dye and a high sensitivity image recording medium further combined with an acid generator can also be obtained. Particularly, it relates to a leuco dye represented by a formula (1) (LD—(A—P1)n) and to an image recording medium which contains the leuco dye (wherein LD represents an acid-sensitive leuco dye mother nucleus, —A represents the residue of an acidic group (—AH) selected from —SO3H, —CO2H and —P(═O)(OH)xRy, R represents a hydrogen atom or a substituent group, x and y are x=1 and y=1 or x=2 and y=0, P1 represents a protecting group which can be removed by the action of light, heat or acid, and n is an integer of 1 or more).

Abstract: A heat-sensitive recording material includes, on a support thereof, a heat-sensitive recording layer containing a diazo compound and a coupler.

Abstract: A product label in which goods figure indicating the form of goods or a portion thereof is printed together with sales information of the goods, and which can associate the content of the goods to some extent through the product label to provide a product label having high sales promotion effect. Particularly, it can provide indication that can be seen easily and effectively by printing the goods figure in a color that associates the goods, for example, in a color similar or identical with the color of the goods or a portion thereof, to give more effective sales promotion, and can also provide indication that can be seen easily and effectively by printing the goods figure in a color different from that of the printed letters for the content of goods to give more effective sales promotion.

Abstract: A non-impact, thermal transfer printing sheet having a base sheet of fibrous paper or synthetic with or without a security device, coated with a composition comprising (1) lactone, spiropyrane coloration, or an iron metallic complexes that reacts with weak an organic acid to produce coloration when the sheet is heated via a thermal head, (2) an activator to accelerate the reaction, (3) absorbent materials to absorb the resulting products of the reaction, and (4) an inorganic phosphorescent ZnS:Cu pigment having a particle size sufficient to produce phosphorescence in a predetermined time and wave-length and a process of making thereof are disclosed. The sheet is capable of being printed using a thermal transfer printing head and providing phosphorescence when activated by ultraviolet light containing wavelengths of between 440 and 640 nm.

Abstract: A heat developable light-sensitive material comprises a support, a light-sensitive layer and a non-light-sensitive layer. The light-sensitive layer contains silver halide and a reducing agent.

Abstract: The present invention discloses a diazo compound represented by any one of the following general formulas (I) to (III). Also, the present invention discloses a heat-sensitive recording material including a substrate and a heat-sensitive layer provided on the substrate, the heat-sensitive recording layer including a diazo compound which is represented by any one of the following general formulas (I) to (III), and a coupler to react with the diazo compound to color the same. According to the present invention, there is provided a diazo compound having a high density of color-developing and good storability, and a heat-sensitive recording material using the diazo compound which has excellent color-developing property, light-resistance property, and storage stability before use.

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: A process of forming a diffusion resistant lenticular element comprising: a) contacting at least one dye-donor element comprising a support having thereon a dye layer comprising an image dye in a binder having an infrared-absorbing material associated therewith, the image dye comprising a nonionic dye capable of being converted to a cationic dye by means of an acid, with a lenticular element comprising a first support having thereon a lenticular array on the opposite side thereof; b) imagewise-heating the dye-donor element by means of a laser; c) transferring a dye image to the first support of the lenticular element; d) contacting the dye image with a mordanting element comprising a second support having thereon in order, a release layer and an adhesive layer of an acidic polymer having a Tg less than about 80° C.

Abstract: A diffusion resistant lenticular element comprising a first support having thereon a lenticular array, the element having thereon a protective element comprising a second support having thereon an adhesive layer of an acidic polymer having a Tg less than about 80° C., the adhesive layer of the protective element being on the side of the first support which does not contain the lenticular array, the adhesive layer containing a laser-induced, cationic dye image.

Abstract: Authenticatable paper and paperboard products are prepared by printing images such as microdots on one or both surfaces of the paper using a starch containing authenticating solution. The images are not detectable by the human eye, but can be revealed with the application of a standard iodine solution.

Abstract: Pressure-sensitive copying material comprises a substrate carrying isolated droplets of an oil solution of chromogenic material confined within respective pressure-rupturable barriers. The chromogenic material develops a colour other than blue or black on contact with colour developer and comprises a component which is fluorescent. This enables the authenticity of the copying material to be verified by irradiation with ultra-violet light to produce fluorescence. The fluorescent material can be, for example 2,2-bis(4-{2-[4-diethylaminophenyl]-quinazolin-4-yloxy}phenyl) propane or 1-(3-methoxy-4-dodecyloxyphenyl)-2-(2'-quinolyl)ethylene. Non-fluorescent chromogenic material(s) are preferably used in combination with the fluorescent chromogenic material(s).

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: A tamper evident document for use with an impact printer having an inked ribbon, which document comprises, a substrate having a first surface and a second surface, the first surface being adapted to receive a principal visible colored image by transfer from the inked ribbon of an impact printer and being substantially free from color forming compositions which react to form visible colored images, the second surface being coated with a self-contained pressure-sensitive chromogenic composition capable of reacting to form a visible colored mirror image on the second surface, the substrate being sufficiently translucent such that the second visible colored mirror image could be viewed from the first surface, if said second visible image were not totally blocked by said principal visible image, so as to determine whether the principal and second visible colored mirror images are in register.

Abstract: This invention includes novel 2,5-bis-?bis?(4-amino)phenyl!hydroxymethyl!substituted furan, thiophene, and pyrrole color-forming compounds and the reaction of these compounds or 2-mono-?bis?(4-amino)phenyl!hydroxymethyl!substituted furan, thiophene, and pyrrole color-forming compounds to form colored compounds. The invention also includes the use of these color-forming compounds in the manufacture and imaging of thermal imaging papers and pressure-sensitive imaging papers.

Abstract: Pressure-sensitive copying material comprises a substrate carrying isolated droplets of an oil solution of chromogenic material confined within respective pressure-rupturable barriers. The chromogenic material develops a colour other than blue or black on contact with colour developer and comprises a component which is fluorescent. This enables the authenticity of the copying material to be verified by irradiation with ultra-violet light to produce fluorescence. The fluorescent material can be, for example 2,2-bis(4-{2-?4-diethylaminophenyl!-quinazolin-4-yloxy}phenyl) propane or 1-(3-methoxy-4-dodecyloxyphenyl)-2-(2'-quinolyl)ethylene. Non-fluorescent chromogenic material(s) are preferably used in combination with the fluorescent chromogenic material(s).

Abstract: A light- and heat-sensitive recording material is disclosed, comprising a support provided thereon a light- and heat-sensitive layer containing a photo-color-forming element comprising a photodecomposable compound and an element capable of forming a color upon reaction with a decomposition product of the photodecomposable compound, wherein the photo-color-forming element is imagewise heated so as to be mixed to thereby form a latent image and the latent image is further exposed to light to form a color; at least one of the photodecomposable compound and the element capable of forming a color upon reaction with the decomposition product of the photodecomposable compound being dispersed through solution in an organic solvent.

Abstract: An image-forming element comprising a substrate, and an image-forming medium comprising (a) a compound absorbing at a first wavelength in the UV/blue region and (b) a dye absorbing at a second wavelength which is longer than the first wavelength, irradiation at said second wavelength bleaching absorption of said compound at said first wavelength, said element being free of thermally unstable urea and/or carbamate molecules.

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: This invention includes novel sultine compounds and the reaction of these compounds to form colored compounds. The invention also includes the use of these color-forming compounds in the manufacture and imaging of thermal imaging papers and pressure-sensitive imaging papers.

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: Pressure-sensitive copying material comprises 3,1 benzoxazine chromogenic material(s) in a solvent comprising vegetable oil and/or a mono-, di or tri-functional ester of a non-aromatic mono-carboxylic acid having a straight or branched hydrocarbon chain with at least three carbon atoms in the chain in addition to the carboxyl carbon atom and an inorganic colour developer. The surface pH of the colour developer is not more than about 8.7, which gives rise to enhanced image intensity and fade resistance compared with the use of 3,1 benzoxazine chromogenic materials in the same solvent with the same colour developer at higher surface pH values.

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: 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: A direct thermal imaging process wherein a non-photosensitive direct thermal recording material is heated dot-wise, and said direct thermal recording material comprises an imaging layer containing uniformly distributed in a film-forming polymeric binder (i) one or more substantially light-insensitive organic silver salts, said silver salt(s) being uniformly in thermal working relationship with (ii) one or more organic reducing agents therefor, however neither including 3,5-dihydroxybenzoic acid as acidic reagent nor di-tert-butyl-p-cresol as a sole reducing agent, characterized in that said imaging layer contains at least one polycarboxylic acid and/or anhydride thereof in a molar percentage of at least 20 with respect to said silver salt(s).

Abstract: This invention relates to improved imaging systems based on the formation of yellow colored coordination compounds of transition metals with certain ligands. These coordination compounds have been found to provide excellent yellow colors when used in pressure sensitive carbonless copy-papers wherein the image is formed by the reaction of a color-forming compound with transition metal salts such as those of nickel, cobalt, iron, copper, and similar materials. These yellow color-formers have the advantage of high solubility in encapsulation solvents and have less color on Zn.sup.2+ containing CB sheets. Use of these yellow color-formers with other metal complex color-formers such as N-(monosubstituted)dithiooxamide color-formers and N,N'-(disubstituted)dithiooxamides results in the formation of black images.

Abstract: An imaging process uses an imaging medium comprising a polymer having a plurality of first groups. This polymer is imagewise contacted with an imaging reagent comprising a plurality of second groups, thus causing, in the areas of the medium exposed to the imaging reagent, the second groups to react with the first groups and form a colored material, and thereby forming an image on the imaging medium. One of the first and second groups comprises a benzotriazinone or benzothiatriazine-4,4-dioxide benzotriazinone moiety and the other comprises a naphthol or a pyrazalone moiety.

Abstract: An image-forming material which includes on a support a coating layer containing at least (A) a microcapsule, which encapsulates (1) a leuco dye that forms color upon oxidative development and (2) a photooxidizing agent and (B) a reducing agent, wherein the leuco dye is a xanthene derivative represented by the following formula (1): ##STR1## wherein R.sup.1 and R.sup.2, which may be the same or different, each designates a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group; R.sup.3 designates a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group; R.sup.4 and R.sup.5 which may be the same or different, each designates a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a trifluoromethyl group, a substituted carbonyl group, or a substituted sulfonyl group; and R.sup.6 designates a hydrogen atom, an alkyl group, or a substituted carbonyl group; andwherein R.sup.1 and R.sup.

Abstract: This invention relates to improved imaging systems based on the formation of yellow colored coordination compounds of transition metals with certain ligands. These coordination compounds have been found to provide excellent yellow colors when used in pressure sensitive carbonless copy-papers wherein the image is formed by the reaction of a color-forming compound with transition metal salts such as those of nickel, cobalt, iron, copper, and similar materials. These yellow color-formers have the advantage of high solubility in encapsulation solvents and have less color on Zn.sup.2+ containing CB sheets. Use of these yellow color-formers with other metal complex color-formers such as N-(monosubstituted)dithiooxamide color-formers and N,N'-(disubstituted)dithiooxamides results in the formation of black images.

Abstract: A thermal recording sheet provided with a thermal color developing layer containing colorless or pale colored basic chromogenic dye, a color developer of Formula (I) and at least one of o-xylylene-bis-(phenylether) and 4-(m-methylphenoxymethyl) bisphenyl as a sensitizer. ##STR1## (wherein R is propyl, isopropyl, or butyl.

Abstract: A novel class of N-substituted triarylmethane sulfonamides is provided which undergo reversible oxidation into colored form and reversible reduction of the oxidized form into colorless form. Preferred embodiments comprise xanthene sulfonamides having N-aryl substituents, e.g., hydroquinone substituents. These compounds possess redox potentials ranging between about +200 to -500 millivolts and thus are useful as dyes for producing photographic, photothermographic, thermal, and pressure-induced images, as well as being useful as redox indicators in a wide variety of biological and chemical reactions.

Abstract: There is disclosed an optical retrieval apparatus which uses a laser for illuminating an optical element. A sensor responds to modulated light from the optical element to produce electrical signals. The optical element has a substrate and on the surface of the substrate, a dye containing recording layer and a light reflecting layer. The improvement is that the dye is a leuco dye.

Abstract: Compositions containing(a) at least one 1,4-diketopyrrolo[3,4-c]pyrrole of the formula I, II, IIa, III or IV ##STR1## and (b) an auxiliary redox system from the ferrocyanide, ferrocene or ammonium iron(II) sulfate series in combination with at least one conductive salt (c), where, in the formula I,R and R.sub.2 are, for example, --H and R.sub.1 is --SO.sub.3 Na,in the formulae II and IIa, R and R.sub.3 are, for example, --H, R.sub.1 is --SO.sub.3 H and p is 3,in the formula III, R.sub.4 and R.sub.5 are, for example, phenyl and R.sub.6 and R.sub.7 are, for example, methyl, andin the formula IV R.sub.8 and R.sub.9 are, for example, phenyl,are suitable as electrochromic materials in display systems.

Abstract: A light-sensitive image-forming material is disclosed, comprising a support having thereon a recording layer containing a leuco dye which forms color upon oxidative development, a photo-oxidizing agent and a reducing agent, wherein the leuco dye is an xanthene compound having a cyclic amino group at the 2-position. The light-sensitive image-forming material of the present invention provides an image having satisfactory color density and stability to light after imagewise exposure and fixation.

Abstract: There is described a pressure-sensitive recording and transfer material containing in a first sheet a coating comprising one of the components (A) and (B) or a solvent for these components and in a second sheet the other or both of the components (A) and (B) and an electron-attracting and colour-developing material as component (C),(A) being a polycyclic compound of the formula ##STR1## where X is a monocyclic or polycyclic aromatic or heteroaromatic radical, Y is a substituent which is detachable as an anion, Q.sub.1 is --O--, --S--, ##STR2## Q.sub.2 is --CH.sub.2 --, --CO--, --CS-- or --SO.sub.2 --, R is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.10 cycloalkyl, aryl, such as phenyl, or aralkyl, such as benzyl, and the ring A, which may be substituted, is an aromatic or heterocyclic radical of 6 ring atoms with or without a fused aromatic ring which may likewise be substituted, and(B) being an organic condensation component.

Abstract: A heat sensitive recording material comprising a support and a recording layer formed on the support, the recording layer comprising, as essential components, a colorless or light-colored electron donative dyestuff, an acidic substance to let the electron donative dyestuff form a color when heated, and a binder, wherein 2-[(phenylthio)methyl]naphthalene is incorporated in the recording layer.

Abstract: A heat-sensitive recording material which contains(A) a polycyclic compound of the formula ##STR1## in which X is a monocyclic or polycyclic aromatic or heteroaromatic radical,Y is a substituent detachable as an anion,Q.sub.1 is --O--, --S--, >N--R or >N--NH--R,Q.sub.2 is --CH.sub.2 --, --CO--, --CS-- or --SO.sub.2 -- andR is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.10 cycloalkyl, aryl such as phenyl or aralkyl such as benzyl, andring A is an aromatic or heterocyclic radical having 6 ring atoms, which can have an aromatic fused ring, it being possible for both ring A and the fused ring to be substituted, and(B) an organic condensable complex compound of a zinc salt.

Abstract: Leuco dyes are provided which comprise the coupling product of a N-acyl substituted aromatic amino color developer and a dye-forming coupler moiety substituted at the coupling carbon with a thermally removable leaving group. Thermal imaging systems employing these leuco dyes have the advantage of reduced bubble formation relative to thermal imaging systems employing prior art leuco dyes containing a group which thermally fragments into one or more gases.