WO1993001941A1

WO1993001941A1 - Dye diffusion transfer imaging with infrared laser diodes and croconium dyes

Info

Publication number: WO1993001941A1
Application number: PCT/US1992/005608
Authority: WO
Inventors: Reid E. Kellogg; Sheau-Hwa Ma
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1991-07-17
Filing date: 1992-07-10
Publication date: 1993-02-04
Anticipated expiration: 1994-01-17

Abstract

There is disclosed donor elements for laser-induced thermal imaging processes containing infrared absorbing croconium dyes of structure (I), wherein R?1, R2, R3, and R4¿ are each independently hydrogen, hydroxyl, halogen, cyano, alkoxy, aryloxy, acyloxy, aryloxycarbonyl, alkoxycarbonyl, sulfonyl, carbamoyl, acyl, acylamido, alkylamino, arylamino, or a substituted or unsubstituted alkyl, aryl, or heteroaryl group; or any of said R?1, R2, R3, and R4¿ are combined with any of R?5, R6, R7, or R8¿ or with each other to form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; R?5, R6, R7, and R8¿ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted aryl or heteroaryl group having 5 to 10 atoms; or (R?5 and R6) or (R7 and R8¿) are joined to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 to 4.

Description

DYE DIFFUSION TRANSFER IMAGING WITH INFRARED LASER DIODES AND CRCCONIOM DYES

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to thermal imaging. More particularly this invention relates to donor elements for laser-induced thermal imaging processes in which the donor element contains certain infra-red absorbing croconiu compounds.

Background of the Invention

Thermal imaging processes are well-known. In these processes a donor element comprising a colorant is heated, by, for example, a thermal head or an infra-red laser, causing the colorant to be transferred to a receptor sheet. Depending on the process, the colorant may be a dye or pigment or a mixture of dyes and/or pigments. Imagewise heating of the donor element reproduces the corresponding image on the receptor sheet. Transfer in register to the same receptor sheet from several differently colored donor elements produces a multicolored image. Different single colored donor elements or a multicolor donor element carrying different colors in different regions which can be brought into position in turn can be used for transfer.

When an infra-red laser is used for thermal transfer, only a single, small, selected area is heated at one time. Since only a small region of colorant is heated and transferred, the image can be built up pixel by pixel. Computer control of such processes allows multicolor images of high definition to be produced at high speed. This process is disclosed in Baldock, UK Patent 2,083,726.

In the laser-induced thermal dye transfer process, the donor element comprises a heat transferable dye, sometimes called a thermal transfer dye, usually in a formulation with a binder, supported on a substrate. The dye donor element is contacted with a receptor sheet, and the surface of the substrate irradiated with an infra-red laser to transfer the dye to the receptor sheet. For the heat transferable dye to be directly heated by the laser, a dye which strongly absorbs the wavelength of the exciting laser is required. This need to match the infra-red absorption of the dye to the emission of the laser greatly restricts the number of dyes which can be used in the laser-induced thermal transfer process.

As an alternative, the dye may be heated indirectly by incorporating a separate radiation absorber, such as carbon black, into the dye layer. However, carbon black has a tendency to aggregate or agglomerate when coated so that the absorber is not uniformly distributed in the donor element. In addition, small carbon black particles tend to be carried over with the dye, contaminating the image. Alternatively, an infra-red absorbing compound can be added to the dye layer. Dye donor layers containing infra-red absorbing materials have been disclosed by, for example. Barlow, U.S. Patent 4,778_f .28, which discloses thermal printing media comprising infra-red absorbing poly(substituted)phthalocyanine compounds; DeBoer, EPO Application 0 321 923, which discloses infra-red absorbing donor elements which contain cyanine dyes; and DeBoer, U.S. Patent 4,942,141 and U.S. Patent application 07/603,278, filed 10/25/90 allowed 12/13/90,, which disclose infra-red absorbing donor elements which contain selected squarylium dyes. However, there is a continuing need for infra-red absorbing materials which may be used to advantage in laser-induced thermal transfer processes.

Summary of the Invention

This invention is a donor element for a laser- induced thermal transfer process, said donor element comprising a support bearing thereon a colorant layer, said colorant layer comprising a colorant and an infra¬ red absorbing material, said infra-red absorbing material having the structure:

wherein:

R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, cyano, alkoxy, aryloxy, acyloxy, aryloxycarbonyl, alkoxycarbonyl, sulfonyl, carbamoyl, acyl, acylamido, alkylamino, arylamino, or a substituted or unsubstituted alkyl, aryl, or heteroaryl group; or any of said R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, or R⁸ or with each other to form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted aryl or heteroaryl group having 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 to 4.

Detailed Description of the Invention The invention is a donor element for thermal transfer processes particularly adapted for use in laser-induced thermal transfer imaging. The donor element comprises a colorant layer and a support.

Colorant Laver The colorant layer comprises a heat-transferable colorant, an infra-red absorbing material, and, preferably, a binder.

The infra-red absorbing material must have a strong absorption in the emission region of the exciting laser and should have good thermal stability so that it is not decomposed by the incident radiation. The material is preferably substantially non-transferable so it is not transferred during imaging. It is preferred that it be essentially non-absorbing in the visible so that small amounts, if transferred, will not affect the image. It is also preferred that the material be soluble in a solvent which can be used to coat the colorant layer onto the support.

Infra-red absorbing materials of the following structure are used in the colorant layer of the instant invention:

R¹, R², R³, and R⁴ may be independently chosen from a number of groups, provided the presence of the group does not adversely affect the properties of the infra¬ red absorbing material required for the operation of the invention, such as, for example, chemical stability, thermal stability, solubility, and absorption spectrum. R¹, R², R³, and R⁴ may be: hydrogen; hydroxyl; halogen, such as, for example, chlorine, bromine, and fluorine; cyano; alkoxy, such as, for example, methoxy, ethoxy, 2-ethoxyethoxy, and benzyloxy; aryloxy, such as, for example, phenoxy, 3-pyridyloxy, 1-naphthyloxy, and 3-thenyloxy; acyloxy, such as, for example, acetoxy, benzyloxy, and phenylacetoxy; aryloxycarbonyl, such as, for example, phenoxycarbonyl; alkoxycarbonyl, such as, for example, methoxycarbonyl; sulfonyl such as, for example, methanesulfonyl and β-toluenesulfonyl; carbamoyl, such as, for example, N-phenylcarbamoyl; acyl, such as, for example, benzoyl and acetyl; acylamido, such as, for example, p-toluenesulfonamido, benzamido, and acetamido; alkylamino, such as, for example, diethylamino, ethylbenzylamino, and i- butylamino; arylamino, such as, for example, anilino and diphenylamino; or a substituted or unsubstituted alkyl, aryl, or heteroaryl group, such as, for example, methyl, ethyl, cyclopentyl, 2-ethoxyethyl, benzyl, phenyl, 2- imidazolyl, 2-naphthyl, and 4-pyridyl. R¹, R², R³, and R⁴ may also each be independently combined with R⁵, R⁶, R⁷, and R⁸, or with each other, to form a 5- to 7- membered substituted or unsubstituted carbocyclic or heterocyclic ring, such as, for example, benzene, naphthalene, thiazole, benzothiazole, oxazole, benzoxazole, selenazole, benzoselenazole, thiazoline, oxazoline, quinoline, isoquinoline, pyridine, imidazole, benzimidazole, and indazoline. R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen; a substituted or unsubstituted alkyl or cycloalkyl group having 1 to 6 carbon atoms, such as, for example, methyl, ethyl, cyclopentyl, t-butyl, 2-ethoxyethyl, n-hexyl, and benzyl; or an aryl or heteroaryl group having 5 to 10 atoms, such as, for example, phenyl, naphthyl, pyridyl, and thiphenyl. (R⁵ and R⁶) or (R⁷ and R⁸) may also joined to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring, n and m are each independently 1 to 4.

Where substitution is possible, any of the groups may be substituted by any of the well-known organic substituents, such as, for example: alkyl; alkoxy; halogen; cyano; sulfonyl; amino; alkyl amino; dialkylamino; etc., provided the presence of the substituent does not adversely affect the properties of the infra-red absorbing material required for the operation of the invention. The alkyl groups comprising any of these substituents preferably contain 1 to 6 carbon atoms.

Useful croconium compounds are disclosed in Rillaers, U.S. Patent 3,793,313, the disclosure of which is incorporated herein by reference. Representative croconium dyes are listed in column 4, line 3, to column 5, line 15. Additional useful croconium compounds are listed in Oguchi, Japanese Patent Application 60-272,808 (1985) rChemical Abstracts. 108. 66027u], the disclosure of which is incorporated herein by reference. Examples of useful croconium compounds are CR1, CR2, CR3, CR4, CR5, CR6, and CR7.

In a preferred embodiment of this invention, R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, alkyl of 1 to 4 carbon atoms, alkoxyl of 1 to 4 carbon atoms, or substituted or unsubstituted aryl or heteroaryl; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms, or a substituted or unsubstituted aryl or heteroaryl of 5 to 10 atoms; or any of R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, and R⁸ or with each other to a form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; or (R⁵ and R⁶) and/or (R⁷ and R⁸) are joined together to form a 5- to 7- membered substituted or unsubstituted heterocyclic ring; and n and are each independently 1 or 2.

In a more preferred embodiment of this invention, the infra-red absorbing material has the following structure:

wherein: R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms or a substituted or unsubstituted aryl having from 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined together to form a 5- or 6-membered heterocyclic ring; R⁹, R¹⁰, R¹², and R¹³ are each independently hydrogen, methyl, or ethyl; or (R⁵ and R⁹) , (R⁶ and R¹⁰) , (R⁷ and R¹²) or (R⁸ and R¹³) are joined together to form a 5- or 6- membered nitrogen-containing heterocyclic ring with the proviso that (R⁵ and R⁹) and (R⁶ and R¹⁰) may not both be joined to form 5-membered rings at the same time and the further proviso that (R⁷ and R¹²) and (R⁸ and R¹³) may not both be joined to form 5-meιrιbered rings at the same time; and R¹¹ and R¹⁴ are each independently hydrogen, hydroxyl, or methyl. In an even more preferred embodiment of this invention, the infra-red absorbing material is symmetrical, that is, (R⁵ and R⁷) , (R⁶ and R⁸) , (R⁹ and R¹²), (R¹⁰ and R¹³), and (R¹¹ and R¹⁴) are the same. In the preferred compounds of this embodiment, R⁵ and R⁶ are each independently unsubstituted alkyl of 1 to 4 carbon atoms or joined together to form a 5- or 6- me bered heterocyclic ring; R⁹ and R¹⁰ are hydrogen or methyl; or (R⁵ and R⁹) or (R⁶ and R¹⁰) are joined together to form a 5- or 6-membered ring with the proviso that (R⁵ and R⁹) and (R⁶ and R¹⁰) may not both be joined to form 5-membered rings at the same time; and R¹¹ is hydrogen, hydroxyl, or methyl. In the most preferred compounds, R¹¹ is hydroxyl. The most preferred compounds are CR1, CR2, and CR3.

Materials identified herein as CR1, CR2, CR3, CR4, CR5, CR6, and CR7 have the following structures:

CR4

CR5

The infra-red absorbing materials may be prepared by conventional synthetic methods. The synthesis of croconium compounds, such as, for example, CR5, CR6, and CR7 is disclosed in Rillaers, U.S. Patent 3,793,313, the disclosure of which is incorporated herein by reference. Syntheses are given in column 5, line 16, to column 6, line 36. Syntheses of croconium compounds, such as, for example, CR3 and CR4, are also disclosed in Oguchi, Japanese Patent Application 60-272,808 (1985) rchemiπa] Abstracts, 108_f 66027u], the disclosure of which is incorporated herein by reference. CR3, for example, was prepared from the reaction of -N,N-dimethylaminophenol with croconic acid.

The infra-red absorbing materials may be present in the donor layer in any concentration which is effective for the intended purpose. In general, concentrations of 0.1% to 10% of the coating weight have been found to be effective. A preferred concentration is 1% to 5% of the total coating weight.

The colorant layer comprises a heat-transferable colorant or a mixture of heat-transferable colorants. A heat-transferable colorant is a colorant, such as, for example, a dye or a pigment, which is transferred from the donor element to the receptor sheet by the action of heat. On transfer it produces the desired color on the receptor sheet. Important criteria for the selection of a heat-transferable colorant are its thermal properties, brightness of shade, light and heat fastness, and facility of application to the support. For suitable performance, the colorant should transfer evenly, in a predetermined relationship to the heat applied, so that the intensity of color on the receptor sheet is smoothly related to the heat applied and good density gradation is attained. The colorant must be migrate from the donor element to the receiver sheet at the imaging energies employed, generally 0.2 to 2 J/cm².

Useful heat-transferable colorants include: (a) pigments dispersed in polymeric matrices which will soften or melt on heating, and (b) dyes, such as, for example, sublimable dyes. Useful sublimable dyes, available from Crompton and Knowles (Reading, PA) , include: Intratherm® Dark Brown (azo type. Disperse Brown 27), Intratherm® Pink 1335NT (anthraquinone type); Intratherm® Brilliant Red P-1314NT (anthraquinone type, Disperse Red 60) ; Intratherm® Red P-1339 (anthraquinone type. Disperse Violet 17) ; Intratherm® Blue P-1305NT (anthraquinone type. Disperse Blue 359) ; and Intratherm® Yellow 343NT (quinoline type. Disperse Yellow 54) . Representative sublimable dyes are disclosed in: Gregory, U.S. Patent 4,764,178; Hotta, U.S. Patent

4,541,830; Moore, U.S. Patent 4,698,651; Evans, U.S. Patent 4,695,287; Weaver, U.S. Patent 4,701,439; DeBoer, U.S. Patent 4,772,582; and DeBoer, U.S. Patent 4,942,141. The heat-transferable colorant and infra-red absorbing material are preferably dispersed in a polymeric binder. Typical binders include, but are not limited to: cellulose derivatives, such as, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate^'hydrogen phthalate; polyacetals, such as pol vinyl butyral; waxes having a softening or melting point of about 60°C to about 150°C; acrylate and methacrylate polymers and copolymers; polycarbonate; copolymers of styrene and acrylonitrile; polysulfones; and poly(phenylene oxide) . The binder may be used at a coating weight of about 0.1 to about 5 g/m².

It will be recognized that the infra-red absorbing material and the heat-transferable colorant may be present in separate layers on the support. Such an arrangements is considered to be equivalent to that described herein.

Support Any material which is dimensionally stable, capable of transmitting the radiation from the infra-red laser to the colorant layer, and not adversely affected by this radiation can be used as the support. Such materials include, but are not limited to: polyesters, such as, for example, polyethylene terephthalate; polyamides; polycarbonates; glassine paper; cellulose esters; fluoropolymers; polyethers; polyacetals; polyolefins; etc. A preferred support material is polyethylene terephthalate film. The support typically has a thickness of from about 2 to about 250 microns and may comprise a subbing layer, if desired. A preferred thickness is about 10 microns to about 50 microns.

Although the colorant layer can be applied to the support as a dispersion in a suitable solvent, application from solution is preferred. Any suitable solvent may be used to coat the colorant layer. The colorant layer may be coated onto the support using conventional coating techniques or it may be printed thereon by a printing technique, such as, for example, gravure printing. ecep or Sheet The receptor sheet typically comprises a support and an image-receiving layer. The support is comprised of a dimensionally stable sheet material. It may be a transparent film, such as, for example, polyethylene terephthalate, polyether sulfone, a polyimide, a poly(vinyl alcohol-co-acetal) , or a cellulose ester, such as for example, cellulose acetate. The support may also be opaque, such as, for example, polyethylene terephthalate filled with a white pigment such as titanium dioxide, ivory paper, or synthetic paper, such as Tyvek® spunbonded polyolefin.

The image receiving layer may comprise a coating of, for example, a polycarbonate, a polyurethane, a polyester, polyvinyl chloride, styrene/acrylonitrile copolymer, poly(caprolactone) , and mixtures thereof. The image receiving layer may be present in any amount which is effective for the intended purpose. In general, good results have been obtained at coating weights of 1 to 5 g/m².

Colorant Transfer The donor elements are used to form a colored image by thermal colorant transfer. This process comprises imagewise exposure of the donor element with an infra¬ red laser so that colorant is transferred to the receptor sheet to form a colored image.

The donor element may be used in sheet form or in the form of a continuous roll or ribbon. The donor element may comprise a single color or it may comprise alternating areas of different colors, such as, for example, cyan, magenta, yellow, and black.

Although various types of lasers may be used to effect transfer of the heat-transferable colorant from the donor element to the receiver sheet, diode lasers emitting in the region of 750 to 870 nm offer substantial advantage in terms of their small size, low cost, stability, reliability, ruggedness, and ease of modulation. Diode lasers emitting in the range of 800 to 830 nm are preferred for use with the donor elements of this invention. Such lasers are commercially available from, for example, Spectra Diode Laboratories (San Jose, CA) . A transfer assemblage comprises a donor element and a receiver sheet in which the colorant layer of the donor element is contiguous to the image receiving layer of the receiver sheet. This assemblage may be preassembled as an integral unit when a single colored image is desired. This may be done by reversibly adhering the donor element and the receiver sheet together at their margins. After imagewise exposure, the they are separated to reveal the image on the receiver sheet. When a multicolor image is to be produced, the assemblage is formed a plurality of times. After the first colored image is transferred, the assemblage is separated and a second donor element (or another area of the same donor element which comprises a differently colored heat-transferable colorant) is brought in contact with the receiver sheet and imagewise exposed in register with the first image. The process is repeated with donor elements containing differently colored heat- transferable colorants as many times as desired. A preferred process consists of transferring cyan, yellow, and magenta images to produce a three colored image.

The donor element of this invention is adapted for the production of both single color and multicolor colored images by a laser-induced thermal transfer process. It can be used to obtain prints of images which have been recorded electronically by various electronic devices, such as color video cameras. It can also be used to generate hard copy output in various proofing applications.

The advantageous properties of this invention can be observed by reference to the following examples which illustrate, but do not limit, the invention.

EXAMPLES GLOSSARY

CAB Cellulose acetate butyrate (17% butyl); Aldrich, Milwaukee, WI

CR1 Ethanaminium, N-(4-(3-(4-(diethylamino)- 2-hydroxyphenyl)-2-hydroxy-4,5-dioxo-2- cyclopenten-1-ylidene)-3-hydroxy-2,5- cyclohexadien-1-ylidene)-N-ethyl-, hydroxide, inner salt; λmax 822 ε nm;

214,000; CAS 93754-65-5

CR2 lH-Benzo<i, j>quinolizinium, 2,3,5, 6,7, 9- hexahydro-8-hydroxy-9-(2-hydroxy-3- (2,3, 6,7-tetrahydro-8-hydroxy-lH,5H- benzo<i,j>quinolin-9-yl)-4,5-dioxo-2- cyclopenten-1-ylidene) , hydroxide, inner salt; λmax 854 nm; ε 204,000

Lexan® 1500 Polycarbonate; General Electric Co., Pittsfield, MA

Lithol Rubine Yellow shade Lithol Rubine flushed in

Polyversyl multipurpose vehicle; 50% pigment, 50% vehicle, 83% solids; C.I. 15850:1; Sun Chemical Corp., Cincinnati, OH

Red P-1339 Intratherm® Red P-1339; C.I. Disperse Violet 17; l-amino-2-bromo-4- hydroxyanthraquinone; CAS 12217-92-4; Crompton & Knowles Corp., Reading, PA

In the examples which follow, "coating solution" refers to the mixture of solvent and additives which is coated on the support, even though some of the additives may be in suspension rather than in solution. Amounts are expressed in parts by weight.

Exam le 1

A coating solution containing the following ingredients, expressed in parts by weight, was made up: Red P-1339, 0.20; Lexan® 1500, 0.20; CR1, 0.008; and dichloromethane, 9.62. The composition was stirred to completely dissolve the solids and coated on about 4 mil (about 100 micron) thick polyethylene terephthalate film with a doctor knife at about 2 mil (about 50 micron) wet gap and air dried to form the donor element.

The coated side of the donor element was contacted with a receptor sheet of Tektronix thermal transfer paper (Tektronix Co., Wilsonville, OR) by tightly taping them together on a test drum to form a thermal transfer assemblage. The uncoated side of the donor element was exposed on a rotating drum with a 100 mW infra-red laser emitting at 830 nm (Spectra Diode Laboratories, Inc., San Jose, CA) . At 0.38 J/cm², bright magenta lines about 8 micron wide were obtained on the receptor sheet. A control with no infra-red absorbing materials showed no image. Example 2 A coating solution containing the following ingredients, was made up: Red P-1339, 0.20; CAB, 0.20; CR1, 0.008; and dichloromethane, 9.62. The composition was dissolved, coated, and imaged as^" in Example 1. At 0.38 J/cm², bright magenta lines about 8 micron wide were obtained on the receptor sheet.

Example 3 A coating solution containing the following ingredients, was made up: Red P-1339, 0.20; Lexan® 1500, 0.20; CR2, 0.008; and dichloromethane, 9.62. The composition was dissolved, coated, and imaged as in Example 1. At 0.2 J/cm², bright magenta lines about 8 micron lines were obtained on the receptor sheet.

Example 4 A coating solution containing the following ingredients, was made up: Red P-1339, 0.20; CAB, 0.20; CR2, 0.008, and dichloromethane, 9.62. The composition was dissolved, coated, and imaged as in Example 1. At 0.38 J/cm², bright magenta lines about 8 micron wide were obtained on the receptor sheet.

Having described the invention, we now claim the following and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A donor element for a laser-induced thermal transfer process, said donor element comprising a support bearing thereon a colorant layer, said colorant layer comprising a colorant and an infra-red absorbing material, said infra-red absorbing material having the structure:

wherein:

R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, cyano, alkoxy, aryloxy, acyloxy, aryloxycarbonyl, alkoxycarbonyl, sulfonyl, carbamoyl, acyl, acylamido, alkylamino, arylamino, or a substituted or unsubstituted alkyl, aryl, or heteroaryl group; or any of said R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, or R⁸ or with each other to form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted aryl or heteroaryl gro"p having 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 to 4.

2. ' The donor element of claim 1 wherein R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, alkyl of 1 to 4 carbon atoms, alkoxyl of 1 to 4 carbon atoms, or substituted or unsubstituted aryl or heteroaryl; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms, or a substituted or unsubstituted aryl or heteroaryl of 5 to 10 atoms; or any of R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, and R⁸ or with each other to a form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined together to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 or 2.

3. The donor element of claim 2 wherein the colorant layer additionally comprises a binder.

4. The donor element of claim 3 wherein the colorant is a sublimable dye.

5. The donor element of claim 3 wherein the colorant is a pigment.

6. The donor element of claim 1 wherein the infra-red absorbing material has the following structure:

wherein:

R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms or a substituted or unsubstituted aryl having from 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined together to form a 5- or 6-membered heterocyclic ring; R⁹, R¹⁰, R¹¹, and R¹² are each independently hydrogen, methyl, or ethyl; or (R⁵ and R⁹) , (R⁶ and R¹⁰), (R⁷ and R¹²) or (R⁸ and R¹³) are joined together to form a 5- or 6- membered nitrogen-containing heterocyclic ring with the proviso that (R⁵ and R⁹) and (R⁶ and

R¹⁰) may not both be joined to form 5-membered rings at the same time and the further proviso that (R⁷ and R¹²) and (R⁸ and R¹³) may not both be joined to form 5-membered rings at the same time; and

R¹¹ and R¹⁴ are each independently hydrogen, hydroxyl, or methyl. 6. The donor element of claim 5 wherein the colorant layer additionally comprises a binder.

7. The donor element of claim 6 wherein the colorant is a sublimable dye.

8. The donor element of claim 6 wherein the colorant is a pigment.

9. The donor element of claim 5 wherein R⁵ is the same as R⁷, R⁶ is the same as R⁸, R⁹ is the same as R¹²,

R¹⁰ is the same as R¹³, and R¹¹ is the same as R¹⁴.

10. The donor element of claim 9 wherein R⁵ and R⁶ are each independently unsubstituted alkyl of 1 to 4 carbon atoms or joined together to form a 5- or 6- membered heterocyclic ring; R⁹ and R¹⁰ are hydrogen or methyl; or (R⁵ and R⁹) or (R⁶ and R¹⁰) are joined together to form a 5- or 6-membered ring with the proviso that (R⁵ and R⁹) and (R⁶ and R¹⁰) may not both be jc ,ed to form 5-membered rings at the same time; and R¹¹ is hydrogen, hydroxyl, or methyl.

11. The donor element of claim 10 wherein R¹¹ is hydroxyl.

12. The donor element of claim 3 wherein the infra-red absorbing material is CR1, CR2, or CR3.

13. The donor element of claim 10 wherein the colorant layer additionally comprises a binder.

14. The donor element of claim 13 wherein the colorant is a sublimable dye.

15. The donor element of claim 13 wherein the colorant is a pigment.

16. A thermal transfer assemblage for a laser- induced thermal transfer process, said thermal transfer assemblage comprising:

(a) a donor element comprising a support bearing thereon a colorant layer, said colorant layer comprising a colorant and an infra-red absorbing material, said infra-red absorbing material having the structure:

wherein:

R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, cyano, alkoxy, aryloxy, acyloxy, aryloxycarbonyl, alkoxycarbonyl, sulfonyl, carbamoyl, acyl, acylamido, alkylamino, arylamino, or a substituted or unsubstituted alkyl, aryl, or heteroaryl group; or any of said R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, or R⁸ or with each other to ^" form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted aryl or heteroaryl group having 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 to 4; and

(b) a receiver sheet comprising support and an image-receiving layer; wherein said colorant layer of said donor element is contiguous to said image receiving layer of said receiver sheet.

17. The thermal transfer assemblage of claim 16 wherein R¹, R², R³, and R⁴ are each independently hydrogen, hydroxyl, halogen, alkyl of 1 to 4 carbon atoms, alkoxyl of 1 to 4 carbon atoms, or substituted or unsubstituted aryl or heteroaryl; R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, a substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms, or a substituted or unsubstituted aryl or heteroaryl of 5 to 10 atoms; or any of R¹, R², R³, and R⁴ are combined with any of R⁵, R⁶, R⁷, and R⁸ or with each other to a form a 5- to 7-membered substituted or unsubstituted carbocyclic or heterocyclic ring; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined together to form a 5- to 7-membered substituted or unsubstituted heterocyclic ring; and n and m are each independently 1 or 2.

18. The thermal transfer assemblage of claim 17 wherein the colorant layer additionally comprises a binder.

19. The thermal transfer assemblage of claim 18 wherein the colorant is a sublimable dye.

20. The thermal transfer assemblage of claim 18 wherein the colorant is a pigment. 21. The thermal transfer assemblage of claim 16 wherein the infra-red absorbing material has the following structure:

wherein:

R⁵, R⁶, R⁷, and R⁸ are each independently hydrogen, substituted or unsubstituted alkyl or cycloalkyl having from 1 to 6 carbon atoms or a substituted or unsubstituted aryl having from 5 to 10 atoms; or (R⁵ and R⁶) or (R⁷ and R⁸) are joined together to form a 5- or 6-membered heterocyclic ring; R⁹, R¹⁰, R¹¹, and R¹² are each independently hydrogen, methyl, or ethyl; or (R⁵ and R⁹) , (R^δ and R¹⁰) , (R⁷ and R¹²) or (R⁸ and R¹³) are joined together to form a 5- or 6- membered nitrogen-containing heterocyclic ring with the proviso that (R⁵ and R⁹) and (R⁶ and R¹⁰) may not both be joined to form 5-membered rings at the same time and the further proviso that (R⁷ and R¹²) and (R⁸ and R¹³) may not both be joined to form 5-membered rings at the same time; and R¹¹ and R¹⁴ are each independently hydrogen, hydroxyl, or methyl.

21. The thermal transfer assemblage of claim 20 wherein the colorant layer additionally comprises a binder.

22. The thermal transfer assemblage of claim 21 wherein the colorant is a sublimable dye.

23. The thermal transfer assemblage of claim 21 wherein the colorant is a pigment.

24. The thermal transfer assemblage of claim 20 wherein R⁵ is the same as R⁷, R⁶ is the same as R⁸, R⁹ is the same as R¹², R¹⁰ is the same as R¹³, and R¹¹ is the same as R¹ .

25. The thermal transfer assemblage of claim 24 wherein R⁵ and R⁶ are each independently unsubstituted alkyl of 1 to 4 carbon atoms or joined together to form a 5- or 6-membered heterocyclic ring; R⁹ and R¹⁰ are hydrogen or methyl; or (R⁵ and R⁹) or (R⁶ and R¹⁰) are joined together to form a 5- or 6-membered ring with the proviso that (R⁵ and R⁹) and (R⁶ and R¹⁰) may not both be joined to form 5-membered rings at the same time; and R¹¹ is hydrogen, hydroxyl, or methyl.

26. The thermal transfer assemblage of claim 25 wherein R¹¹ is hydroxyl.

27. The thermal transfer assemblage of claim 18 wherein the infra-red absorbing material is CR1, CR2, or CR3.

28. The thermal transfer assemblage of claim 25 wherein the colorant layer additionally comprises a binder.

29. The thermal transfer assemblage of claim 28 wherein the colorant is a sublimable dye.

30. The thermal transfer assemblage of claim 28 wherein the colorant is a pigment.