ALPHA-CYANO ARYLIDENE PYRAZOLONE MAGENTA DYE-DONOR ELEMENT FOR THERMAL DYE TRANSFER

Abstract: A dye-donor element for thermal dye transfer comprises a support having thereon a dye dispersed in a polymeric binder, characterized in that the dye has the formula: wherein R¹ represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; R² represents a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms; a substituted or unsubstituted aryloxy group having from 6 to 10 carbon atoms; NHR⁵; or NR⁵R⁶; R³ and R⁴ each represents R¹; or either or both of R³ and R⁴ can be joined to the carbon atom of the aromatic ring at a position ortho to the position of attachment of the anilino nitrogen to form a 5- or 6-membered ring; or R³ and R⁴ can be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; R⁵ and R⁶ each independently represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; or R⁵ and R⁶ may be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; and Z represents hydrogen or the atoms necessary to complete a 5- or 6-membered ring.

Description: This invention relates to dye-donor elements used in thermal dye transfer which have good hue and dye stability. In recent years, thermal transfer systems have been developed to obtain prints from pictures which have been generated electronically from a color video camera. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then operated on to produce cyan, magenta and yellow electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to the cyan, magenta and yellow signals. The process is then repeated for the other two colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen. Further details of this process and an apparatus for carrying it out are contained in U.S. Patent No. 4,621,271 by Brownstein entitled "Apparatus and Method For Controlling A Thermal Printer Apparatus," issued November 4, 1986. A problem has existed with the use of certain dyes in dye-donor elements for thermal dye transfer printing. Many of the dyes proposed for use do not have adequate stability to light. Others do not have good hue. It is an object of this invention to provide dyes which have good light stability and have improved hues. JP 60/31,563 and JP 60/223,878 relate to arylidene magenta dyes used in a thermal transfer sheet. There is a problem with these dyes, however, with their stability to light. It is an object of this invention to provide arylidene dyes which have improved hue and stability to light and heat. These and other objects are achieved in accordance with this invention which comprises a dye-donor element for thermal dye transfer comprising a support having thereon a dye dispersed in a polymeric binder, characterized in that the dye has the formula: wherein R¹ represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, methoxyethyl, benzyl, 2-methanesulfonamidoethyl, 2-hydroxyethyl, 2-cyanoethyl, methoxycarbonylmethyl, etc.; a cycloalkyl group having from 5 to 7 carbon atoms, such as cyclohexyl, cyclopentyl, etc.; or an aryl group having from 6 to 10 carbon atoms, such as phenyl, pyridyl, naphthyl, p-tolyl, p-chlorophenyl, or m-(N-methyl sulfamoyl)phenyl; R² represents a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms, such as methoxy, ethoxy, methoxyethoxy or 2-cyanoethoxy; a substituted or unsubstituted aryloxy group having from 6 to 10 carbon atoms, such as phenoxy; m-chlorophenoxy; or naphthoxy; NHR⁵; or NR⁵R⁶; R³ and R⁴ each represents R¹; or either or both of R³ and R⁴ can be joined to the carbon atom of the aromatic ring at a position ortho to the position of attachment of the anilino nitrogen to form a 5- or 6-membered ring; or R³ and R⁴ can be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring, such as a pyrrolidine or morpholine ring; R⁵ and R⁶ each independently represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, methoxyethyl, benzyl, 2-methanesulfonamidoethyl, 2-hydroxyethyl, 2-cyanoethyl, methoxycarbonylmethyl, etc.; a cycloalkyl group having from 5 to 7 carbon atoms, such as cyclohexyl, cyclopentyl, etc. or an aryl group having from 6 to 10 carbon atoms, such as phenyl, pyridyl, naphthyl, p-tolyl, p-chlorophenyl, or m-(N-methyl sulfamoyl)phenyl; or R⁵ and R⁶ may be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring, such as a pyrrolidine or morpholine ring; and Z represents hydrogen or the atoms necessary to complete a 5- or 6-membered ring, thus forming a fused ring system such as naphthalene, quinoline, isoquinoline or benzothiazole. In a preferred embodiment of the invention, R¹ is phenyl or methyl. In another preferred embodiment, R³ and R⁴ are each methyl or ethyl. In another preferred embodiment, R² is NR⁵R⁶, wherein each R⁵ and R⁶ is methyl or ethyl. In still another preferred embodiment, R² is NR⁵R⁶, wherein R⁵ and R⁶ are joined together to form, along with the nitrogen to which they are attached, a pyrrolidine or morpholine ring. In yet another preferred embodiment, R² is ethoxy or NHR⁵, wherein R⁵ is methyl or phenyl. In yet still another preferred embodiment, R³ is joined together to form, along with the nitrogen to which it is attached, a 6-membered heterocyclic ring and R⁴ is chloroethyl. The aromatic ring in the formula above may be substituted with various substituents, such as C₁ to C₆ alkyl, C₁ to C₆ alkoxy, halogen, sulfonamido, aryloxy, acyloxy, acylamido, etc. Compounds included within the scope of the invention include the following: These dyes may be prepared using synthetic techniques similar to those disclosed in J. Signalaufzeichnungsmaterielen, 9 , 31 (1981). The dye in the dye-donor element of the invention is dispersed in a polymeric binder such as a cellulose derivative, e.g., cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate or any of the materials described in U. S. Patent 4,700,207 of Vanier and Lum; a polycarbonate; poly(styrene-co-acrylonitrile), a poly(sulfone) or a poly(phenylene oxide). The binder may be used at a coverage of from 0.1 to 5 g/m². The dye layer of the dye-donor element may be coated on the support or printed thereon by a printing technique such as a gravure process. Any material can be used as the support for the dye-donor element of the invention provided it is dimensionally stable and can withstand the heat of the thermal printing heads. Such materials include polyesters such as poly(ethylene terephthalate); polyamides; polycarbonates; glassine paper; condenser paper; cellulose esters; fluorine polymers; polyethers; polyacetals; polyolefins; and polyimides. The support generally has a thickness of from 2 to 30 µm. It may also be coated with a subbing layer, if desired, such as those materials described in U. S. Patents 4,695,288 or 4,737,486. The reverse side of the dye-donor element may be coated with a slipping layer to prevent the printing head from sticking to the dye-donor element. Such a slipping layer would comprise a lubricating material such as a surface active agent, a liquid lubricant, a solid lubricant or mixtures thereof, with or without a polymeric binder. Preferred lubricating materials include those materials disclosed in U. S. Patents 4,717,711, 4,717,712, 4,737,485 and 4,738,950. Suitable polymeric binders for the slipping layer include poly(vinyl alcohol-co-butyral), poly(vinyl alcohol-co-acetal), poly(styrene), poly(vinyl acetate), cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate or ethyl cellulose. The dye-receiving element that is used with the dye-donor element of the invention usually comprises a support having thereon a dye image-receiving layer. The support may be a transparent film such as a poly(ether sulfone), a polyimide, a cellulose ester such as cellulose acetate, a poly(vinyl alcohol-co-acetal) or a poly(ethylene terephthalate). The support for the dye-receiving element may also be reflective such as baryta-coated paper, polyethylene-coated paper, white polyester (polyester with white pigment incorporated therein), an ivory paper, a condenser paper or a synthetic paper such as duPont Tyvek®. The dye image-receiving layer may comprise, for example, a polycarbonate, a polyurethane, a polyester, polyvinyl chloride, poly(styrene- co -acrylonitrile), poly(caprolactone) or mixtures thereof. The dye image-receiving layer may be present in any amount which is effective for the intended purpose. In general, good results have been obtained at a concentration of from 1 to 5 g/m². As noted above, the dye-donor elements of the invention are used to form a dye transfer image. Such a process comprises imagewise-heating a dye-donor element as described above and transferring a dye image to a dye-receiving element to form the dye transfer image. The dye-donor element of the invention may be used in sheet form or in a continuous roll or ribbon. If a continuous roll or ribbon is employed, it may have only the dye thereon as described above or may have alternating areas of other different dyes, such as sublimable cyan and/or magenta and/or yellow and/or black or other dyes. Such dyes are disclosed in U. S. Patents 4,541,830; 4,698,651; 4,695,287; and 4,701,439. Thus, one-, two-, three- or four-color elements (or higher numbers also) are included within the scope of the invention. In a preferred embodiment of the invention, the dye-donor element comprises a poly(ethylene terephthalate) support coated with sequential repeating areas of yellow, cyan and a magenta dye as described above, and the above process steps are sequentially performed for each color to obtain a three-color dye transfer image. Of course, when the process is only performed for a single color, then a monochrome dye transfer image is obtained. A thermal dye transfer assemblage of the invention comprises a) a dye-donor element as described above, and b) a dye-receiving element as described above, the dye-receiving element being in a superposed relationship with the dye-donor element so that the dye layer of the donor element is in contact with the dye image-receiving layer of the receiving element. The above assemblage comprising these two elements may be preassembled as an integral unit when a monochrome image is to be obtained. This may be done by temporarily adhering the two elements together at their margins. After transfer, the dye-receiving element is then peeled apart to reveal the dye transfer image. When a three-color image is to be obtained, the above assemblage is formed on three occasions during the time when heat is applied by the thermal printing head. After the first dye is transferred, the elements are peeled apart. A second dye-donor element (or another area of the donor element with a different dye area) is then brought in register with the dye-receiving element and the process repeated. The third color is obtained in the same manner. The following example is provided to illustrate the invention. Example A magenta dye-donor element was prepared by coating the following layers in the order recited on a 6 µm poly(ethylene terephthalate) support: 1) Subbing layer of duPont Tyzor TBT® titanium tetra-n-butoxide (0.16 g/m²) coated from a n-butyl alcohol and n-propylacetate solvent mixture, and 2) Dye layer containing the magenta dye identified in the Table below (0.36 mmoles/m²), FC-431® surfactant (3M Corp.) (0.002 g/m²), in a cellulose acetate-propionate (2.5% acetyl, 48% propionyl) binder (weight equal to 2.6X that of the dye) coated from a cyclopentanone, toluene, and methanol solvent mixture. A slipping layer was coated on the back side of the element similar to that disclosed in U.S. Patent 4,737,485. A dye-receiving element was prepared by coating a solution of Makrolon 5705® (Bayer AG Corporation) polycarbonate resin (2.9 g/m²) in methylene chloride on a pigmented polyethylene-overcoated paper stock. The dye side of the dye-donor element strip approximately 10 cm x 13 cm in area was placed in contact with the dye image-receiving layer of the dye-receiver element of the same area. The assemblage was clamped to a stepper-motor driven 60 mm diameter rubber roller and a TDK Thermal Bead (No. L-231) (thermostatted at 26°C) was pressed with a force of 8.0 pounds (3.6 kg) against the dye-donor element side of the assemblage pushing it against the rubber roller. The imaging electronics were activated causing the donor/receiver assemblage to be drawn between the printing head and roller at 6.9 mm/sec. Coincidentally, the resistive elements in the thermal print head were pulsed at 29 µsec/pulse at 128 µsec intervals during the 33 msec/dot printing time. A stepped density image was generated by incrementally increasing the number of pulses/dot from 0 to 255. The voltage supplied to the print head was approximately 23.5 volts, resulting in an instantaneous peak power of 1.3 watts/dot and a maximum total energy of 9.6 mjoules/dot. The dye-receiving element was separated from the dye-donor element. The Status A green reflection densities of each stepped image consisting of a series of 11 graduated density steps 1 cm x 1 cm were read. The images were then subjected to High-Intensity Daylight fading (HID-fading) for 7 days, 50 kLux, 5400°K, 32°C, approximately 25% RH and the densities were reread. The percent density loss from D-max (highest density step) was calculated. The λ-max of each dye in an acetone solution was also determined. The following results were obtained: The above results indicate that the dyes according to the invention have substantially improved light stability (lower % fade) in comparison to the Control dyes. Control Compounds Control Compound 1 Control Compound 2 Control Compound 3 Control Compound 4 Control Compound 5 Control Compound 6 Disclosed in JP 60/031,563 and JP 60/223,878.

Claims: 1. A dye-donor element for thermal dye transfer comprising a support having thereon a dye dispersed in a polymeric binder, characterized in that said dye has the formula: wherein R¹ represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; R² represents a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms; a substituted or unsubstituted aryloxy group having from 6 to 10 carbon atoms; NHR⁵; or NR⁵R⁶; R³ and R⁴ each represents R¹; or either or both of R³ and R⁴ can be joined to the carbon atom of the aromatic ring at a position ortho to the position of attachment of the anilino nitrogen to form a 5- or 6-membered ring; or R³ and R⁴ can be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; R⁵ and R⁶ each independently represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; or R⁵ and R⁶ may be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; and Z represents hydrogen or the atoms necessary to complete a 5- or 6-membered ring. 2. The element of Claim 1 characterized in that R¹ is phenyl or methyl, R³ and R⁴ are each methyl or ethyl, and R² is NR⁵R⁶, wherein each R⁵ and R⁶ is methyl or ethyl. 3. The element of Claim 1 characterized in that R² is ethoxy; NR⁵R⁶, wherein R⁵ and R⁶ are joined together to form, along with the nitrogen to which they are attached, a pyrrolidine or morpholine ring; or NHR⁵, wherein R⁵ is methyl or phenyl. 4. The element of Claim 1 characterized in that R³ is joined together to form, along with the nitrogen to which it is attached, a 6-membered heterocyclic ring and R⁴ is chloroethyl. 5. The element of Claim 1 characterized in that said support comprises poly(ethylene terephthalate) and the side of the support opposite the side having thereon said dye layer is coated with a slipping layer comprising a lubricating material. 6. A thermal dye transfer assemblage comprising: a) a dye-donor element comprising a support having thereon a dye layer comprising a dye dispersed in a polymeric binder, and b) a dye-receiving element comprising a support having thereon a dye image-receiving layer, said dye-receiving element being in a superposed relationship with said dye-donor element so that said dye layer is in contact with said dye image-receiving layer, characterized in that said dye has the formula: wherein R¹ represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; R² represents a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms; a substituted or unsubstituted aryloxy group having from 6 to 10 carbon atoms; NHR⁵; or NR⁵R⁶; R³ and R⁴ each represents R¹; or either or both of R³ and R⁴ can be joined to the carbon atom of the aromatic ring at a position ortho to the position of attachment of the anilino nitrogen to form a 5- or 6-membered ring; or R³ and R⁴ can be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; R⁵ and R⁶ each independently represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms; a cycloalkyl group having from 5 to 7 carbon atoms or an aryl group having from 6 to 10 carbon atoms; or R⁵ and R⁶ may be joined together to form, along with the nitrogen to which they are attached, a 5- or 6-membered heterocyclic ring; and Z represents hydrogen or the atoms necessary to complete a 5- or 6-membered ring. 7. The assemblage of Claim 6 characterized in that R¹ phenyl or methyl, R³ and R⁴ are each methyl or ethyl, and R² is NR⁵R⁶, wherein each R⁵ and R⁶ is methyl or ethyl. 8. The assemblage of Claim 6 characterized in that R² is ethoxy; NR⁵R⁶, wherein R⁵ and R⁶ are joined together to form, along with the nitrogen to which they are attached, a pyrrolidine or morpholine ring; or NHR⁵, wherein R⁵ is methyl or phenyl. 9. The assemblage of Claim 6 characterized in that R³ is joined together to form, along with the nitrogen to which it is attached, a 6-membered heterocyclic ring and R⁴ is chloroethyl. 10. The assemblage of Claim 6 characterized in that said support of said dye-donor element comprises poly(ethylene terephthalate) and the side of the support opposite the side having thereon said dye layer is coated with a slipping layer comprising a lubricating material.

Inventors: EVANS, STEVEN C/O EASTMAN KODAK COMPANY, WEBER, HELMUT C/O EASTMAN KODAK COMPANY
Applicants: EASTMAN KODAK COMPANY (A NEW JERSEY CORPORATION)
Application year: 1989
Main classification: B41M5
IPC codes: B41M5, C09B23