Arylidene pyrazolone dye-donor element for thermal dye transfer.

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 59/78895 and U.S. Patent 4,701,439 relate to arylidene yellow dyes used in a thermal transfer sheet. There is a problem with these dyes, however, with their stability to light. There is also another problem in that some of these yellow dyes cause degradation of a cyan dye when both are present in the same color patch, such as green or neutral. It is another object of this invention to provide arylidene dyes which have improved hue and stability to light and heat and which would not cause degradation of other dyes.

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: <chemistry id="chem0001" num="0001"><img file="EP0332924A2_D0001.tif" /></chemistry> 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; NHR⁶; NR⁶R⁷ or the atoms necessary to complete a 6-membered ring fused to the benzene ring, such as O, CH₂, S, NR⁶, etc; R³ and R⁴ each represents or R¹; 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 represents hydrogen; halogen, such as chlorine, bromine, or fluorine; carbamoyl, such as N,N-dimethylcarbamoyl; alkoxycarbonyl, such as ethoxycarbonyl or methoxyethoxycarbonyl; acyl, such as acetyl or benzoyl; a substituted or unsubstituted alkyl or alkoxy group having from 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, methoxyethyl, benzyl, methoxy, ethoxy, 2-methanesulfonamidoethyl, 2-hydroxyethyl, 2-cyanoethyl, methoxycarbonylmethyl, etc.; a cycloalkyl group having from 5 to 7 carbon atoms, such as cyclohexyl, cyclopentyl, etc.; an aryl group having from 6 to 10 carbon atoms, such as phenyl, pyridyl, naphthyl, p-tolyl, p-chlorophenyl, m-(N-methyl sulfamoyl)phenyl; or a dialkylamino group, such as dimethylamino, morpholino or pyrrolidino; R⁶ and R⁷ 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 R⁶ and R⁷ 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; R² is ethoxy or NHR⁶, wherein R⁶ is methyl or phenyl; and R⁵ is hydrogen.

In another preferred embodiment, R² is O and completes a 6-membered ring fused to the benzene ring. In another preferred embodiment, R² is NR⁶R⁷, wherein each R⁶ and R⁷ is methyl or R⁶ is ethyl and R⁷ is phenyl. In another preferred embodiment, R² is NR⁶R⁷, wherein R⁶ and R⁷ are joined together to form, along with the nitrogen to which they are attached, a pyrrolidine or morpholine ring.

In still another preferred embodiment, R³ is methyl, ethyl or butyl and R⁴ is methyl, ethyl, butyl or CO₂CS₂CF₃.

In yet still another preferred embodiment, R³ and R⁴ are joined together to form a pyrrolidine ring.

The above dyes are generally all of yellow hue.

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: <tables id="tabl0001" num="0001"><img file="EP0332924A2_D0002.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP0332924A2_D0003.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0332924A2_D0004.tif" /></tables>

These dyes may be prepared using synthetic techniques similar to those disclosed in J. Indian Chem. Soc., 57, 1108 (1980).

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; 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 oils or semi-crystalline organic solids that melt below 100°C such as 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-<u style="single">co</u>-­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, 4,701,439, 4,757,046, 4,743,582, 4,769,360, and 4,753,922. 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 magenta, cyan and a dye as described above of yellow hue, 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 <ul id="ul0001" list-style="none"><li>a) a dye-donor element as described above, and</li><li>b) a dye-receiving element as described above,</li></ul> 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 examples are provided to illustrate the invention.

Example 1 - Yellow Dye-Donor

A yellow dye-donor element was prepared by coating the following layers in the order recited on a 6 µm poly(ethylene terephthalate) support: <ul id="ul0002" list-style="none"><li>1) Subbing layer of duPont Tyzor TBT® titanium tetra-n-butoxide (0.16 g/m²) coated from n-butyl alcohol, and</li><li>2) Dye layer containing the yellow dye identified in Table 1 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.</li></ul>

A slipping layer was coated on the back side of the element similar to that disclosed in U.S. Patent 4,738,950.

A dye-receiving element was prepared by coating a solution of Makrolon 5705® (Bayer AG Corporation) polycarbonate resin (2.9 g/m² in a methylene chloride and trichloroethylene solvent mixture on an ICI Melinex 990® white polyester support.

The dye side of the dye-donor element strip 1 inch (2.5 mm) wide was placed in contact with the dye image-receiving layer of the dye-receiver element of the same width. The assemblage was fastened in the jaws of a stepper motor driven pulling device. The assemblage was laid on top of a 0.55 (14 mm) diameter rubber roller and a TDK Thermal Bead (No. L-133) and was pressed with a spring at 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 pulling device to draw the assemblage between the printing head and roller at 0.123 inches/sec (3.1 mm/sec). Coincidentally, the resistive elements in the thermal print head were pulse-heated at increments from 0 up to 8 msec to generate a graduated-density image. The voltage supplied to the print head was approximately 22v representing approximately 1.5 watts/dot (12 mjoules/dot) for maximum power.

The dye-receiving element was separated from the dye-donor element. The Status A blue reflection densities of each stepped image consisting of a series of 8 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 was calculated from step 7. The following results were obtained: <tables id="tabl0004" num="0004"><table frame="all"><title>Table 1</title><tgroup cols="4" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39.37mm" /><colspec colnum="2" colname="col2" colwidth="39.37mm" /><colspec colnum="3" colname="col3" colwidth="39.37mm" /><colspec colnum="4" colname="col4" colwidth="39.37mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><u style="single">Dye-Donor Element w/Compound</u></entry><entry namest="col2" nameend="col2" align="center"><u style="single">λ</u>_{<u style="single">max</u>}<u style="single"> (nm)</u></entry><entry namest="col3" nameend="col4" align="center"><u style="single">Status A Blue Density</u></entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" align="center"><u style="single">Init. Dens.</u></entry><entry namest="col4" nameend="col4" align="center"><u style="single">% Loss After Fade</u></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">1</entry><entry namest="col2" nameend="col2" align="right">447</entry><entry namest="col3" nameend="col3" align="char" char=".">2.4</entry><entry namest="col4" nameend="col4" align="right">3</entry></row><row><entry namest="col1" nameend="col1" align="right">2</entry><entry namest="col2" nameend="col2" align="right">444</entry><entry namest="col3" nameend="col3" align="char" char=".">2.4</entry><entry namest="col4" nameend="col4" align="right">5</entry></row><row><entry namest="col1" nameend="col1" align="right">3</entry><entry namest="col2" nameend="col2" align="right">451</entry><entry namest="col3" nameend="col3" align="char" char=".">2.4</entry><entry namest="col4" nameend="col4" align="right">8</entry></row><row><entry namest="col1" nameend="col1" align="right">4</entry><entry namest="col2" nameend="col2" align="right">445</entry><entry namest="col3" nameend="col3" align="char" char=".">1.7</entry><entry namest="col4" nameend="col4" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">5</entry><entry namest="col2" nameend="col2" align="right">451</entry><entry namest="col3" nameend="col3" align="char" char=".">2.5</entry><entry namest="col4" nameend="col4" align="right">6</entry></row><row><entry namest="col1" nameend="col1" align="right">6</entry><entry namest="col2" nameend="col2" align="right">458</entry><entry namest="col3" nameend="col3" align="char" char=".">1.9</entry><entry namest="col4" nameend="col4" align="right">16</entry></row><row><entry namest="col1" nameend="col1" align="right">7</entry><entry namest="col2" nameend="col2" align="right">447</entry><entry namest="col3" nameend="col3" align="char" char=".">2.3</entry><entry namest="col4" nameend="col4" align="right">23</entry></row><row><entry namest="col1" nameend="col1" align="right">8</entry><entry namest="col2" nameend="col2" align="right">451</entry><entry namest="col3" nameend="col3" align="char" char=".">2.3</entry><entry namest="col4" nameend="col4" align="right">3</entry></row><row><entry namest="col1" nameend="col1" align="right">9</entry><entry namest="col2" nameend="col2" align="right">445</entry><entry namest="col3" nameend="col3" align="char" char=".">2.3</entry><entry namest="col4" nameend="col4" align="right">4</entry></row><row><entry namest="col1" nameend="col1" align="right">10</entry><entry namest="col2" nameend="col2" align="right">462</entry><entry namest="col3" nameend="col3" align="char" char=".">2.0</entry><entry namest="col4" nameend="col4" align="right">8</entry></row><row><entry namest="col1" nameend="col1" align="right">11</entry><entry namest="col2" nameend="col2" align="right">458</entry><entry namest="col3" nameend="col3" align="char" char=".">2.3</entry><entry namest="col4" nameend="col4" align="right">4</entry></row><row><entry namest="col1" nameend="col1" align="right">12</entry><entry namest="col2" nameend="col2" align="right">446</entry><entry namest="col3" nameend="col3" align="char" char=".">2.4</entry><entry namest="col4" nameend="col4" align="right">8</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 1</entry><entry namest="col2" nameend="col2" align="right">471</entry><entry namest="col3" nameend="col3" align="char" char=".">1.9</entry><entry namest="col4" nameend="col4" align="right">66</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 2</entry><entry namest="col2" nameend="col2" align="right">457</entry><entry namest="col3" nameend="col3" align="char" char=".">2.1</entry><entry namest="col4" nameend="col4" align="right">41</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 3</entry><entry namest="col2" nameend="col2" align="right">428</entry><entry namest="col3" nameend="col3" align="char" char=".">1.3</entry><entry namest="col4" nameend="col4" align="right">85</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 4</entry><entry namest="col2" nameend="col2" align="right">484</entry><entry namest="col3" nameend="col3" align="char" char=".">1.4</entry><entry namest="col4" nameend="col4" align="right">77</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 5</entry><entry namest="col2" nameend="col2" align="right">434</entry><entry namest="col3" nameend="col3" align="char" char=".">1.6</entry><entry namest="col4" nameend="col4" align="right">18</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Control 6</entry><entry namest="col2" nameend="col2" align="right">447</entry><entry namest="col3" nameend="col3" align="char" char=".">1.9</entry><entry namest="col4" nameend="col4" align="right">15</entry></row></tbody></tgroup></table></tables>

The above results indicate that the dyes according to the invention have substantially improved light stability (lower % fade) in comparison to Control dyes 1-4 and improved light stability and/or hue (λ max closer to 450) in comparison to Control dye 5. While Control Dye 6 has good light stability in this test, see Example 2. <chemistry id="chem0002" num="0002"><img file="EP0332924A2_D0005.tif" /></chemistry><chemistry id="chem0003" num="0003"><img file="EP0332924A2_D0006.tif" /></chemistry>

Example 2 - Yellow and Cyan Donors

Example 1 was repeated except that a cyan dye-donor element was also prepared using cyan dye 1 from U.S. Patent 4,695,287 at a concentration of 0.78 mmoles/m².

The printing was the same as in Example 1 except that sequential transfers were obtained using the yellow dye-donors of Example 1 and the cyan dye-donor described above to obtain a green image. Status A blue and red densities of the green image were read. The images were subjected to HID-fading as in Example 1 and reread. The percent density loss for each dye was calculated from the maximum density step. The following results were obtained. <tables id="tabl0005" num="0005"><table frame="all"><title>Table 2</title><tgroup cols="5" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><u style="single">Dye-Donor Element w/Compound</u></entry><entry namest="col2" nameend="col5" align="center"><u style="single">Cyan-Yellow Interactions</u></entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col3" align="center"><u style="single">Red</u></entry><entry namest="col4" nameend="col5" align="center"><u style="single">Blue</u></entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center"><u style="single">D-Max</u></entry><entry namest="col3" nameend="col3" align="center"><u style="single">% Loss After Fade</u></entry><entry namest="col4" nameend="col4" align="center"><u style="single">D-Max</u></entry><entry namest="col5" nameend="col5" align="center"><u style="single">% Loss After Fade</u></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">1</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.3</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">2</entry><entry namest="col2" nameend="col2" align="char" char=".">2.1</entry><entry namest="col3" nameend="col3" align="right">2</entry><entry namest="col4" nameend="col4" align="char" char=".">2.2</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">3</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.3</entry><entry namest="col5" nameend="col5" align="right">3</entry></row><row><entry namest="col1" nameend="col1" align="right">4</entry><entry namest="col2" nameend="col2" align="char" char=".">2.1</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">1.6</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">5</entry><entry namest="col2" nameend="col2" align="char" char=".">1.9</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.2</entry><entry namest="col5" nameend="col5" align="right">4</entry></row><row><entry namest="col1" nameend="col1" align="right">6</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">1.9</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">7</entry><entry namest="col2" nameend="col2" align="char" char=".">2.2</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.1</entry><entry namest="col5" nameend="col5" align="right">2</entry></row><row><entry namest="col1" nameend="col1" align="right">8</entry><entry namest="col2" nameend="col2" align="char" char=".">2.1</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.1</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">9</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.1</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">10</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">4</entry><entry namest="col4" nameend="col4" align="char" char=".">1.9</entry><entry namest="col5" nameend="col5" align="right">1</entry></row><row><entry namest="col1" nameend="col1" align="right">11</entry><entry namest="col2" nameend="col2" align="char" char=".">2.0</entry><entry namest="col3" nameend="col3" align="right">3</entry><entry namest="col4" nameend="col4" align="char" char=".">2.2</entry><entry namest="col5" nameend="col5" align="right">2</entry></row><row><entry namest="col1" nameend="col1" align="right">12</entry><entry namest="col2" nameend="col2" align="char" char=".">2.1</entry><entry namest="col3" nameend="col3" align="right">8</entry><entry namest="col4" nameend="col4" align="char" char=".">1.5</entry><entry namest="col5" nameend="col5" align="right">6</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 5</entry><entry namest="col2" nameend="col2" align="char" char=".">1.8</entry><entry namest="col3" nameend="col3" align="right">32</entry><entry namest="col4" nameend="col4" align="char" char=".">1.7</entry><entry namest="col5" nameend="col5" align="right">10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Control 6</entry><entry namest="col2" nameend="col2" align="char" char=".">1.5</entry><entry namest="col3" nameend="col3" align="right">36</entry><entry namest="col4" nameend="col4" align="char" char=".">1.5</entry><entry namest="col5" nameend="col5" align="right">15</entry></row></tbody></tgroup></table></tables>

The above results indicate that the compounds of the invention cause significantly less degradation of the cyan dye than the control compounds.

Example 3 - Yellow Dye-Donor

A yellow dye-donor element was prepared by coating the following layers in the order recited on a 6 µm poly(ethylene terephthalate) support: <ul id="ul0003" list-style="none"><li>1) Subbing layer of duPont Tyzor TBT® titanium tetra-n-butoxide (0.16 g/m²) coated from n-butyl alcohol and n-propyl acetate, and</li><li>2) Dye layer containing the yellow dyes 18, 19, 20 and 23 identified above (0.47 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 2.0X that of the dye) coated from a cyclopentanone, toluene, and methanol solvent mixture.</li></ul>

A slipping layer was coated on the back side of the element similar to that disclosed in U.S. Patent 4,738,950.

A dye-receiving element was prepared by coating a solution of Makrolon 5705® (Bayer AG Corporation) polycarbonate resin (2.9 g/m²) and polycaprolactone (0.8 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 Head (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 blue 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 was calculated from a step with an initial density of approximately 1.0. The λ-max of each dye in an acetone solution was also determined. The following results were obtained: <tables id="tabl0006" num="0006"><table frame="all"><title>Table 3</title><tgroup cols="4" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39.37mm" /><colspec colnum="2" colname="col2" colwidth="39.37mm" /><colspec colnum="3" colname="col3" colwidth="39.37mm" /><colspec colnum="4" colname="col4" colwidth="39.37mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><u style="single">Dye-Donor Element w/Compound</u></entry><entry namest="col2" nameend="col2" align="center"><u style="single">Fade Test (days)</u></entry><entry namest="col3" nameend="col3" align="center"><u style="single">λ</u>_{<u style="single">max</u>}</entry><entry namest="col4" nameend="col4" align="center"><u style="single">Status A Blue Density % Loss After Fade</u></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="right">18</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">459</entry><entry namest="col4" nameend="col4" align="right">10</entry></row><row><entry namest="col1" nameend="col1" align="right">19</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">456</entry><entry namest="col4" nameend="col4" align="right">30</entry></row><row><entry namest="col1" nameend="col1" align="right">20</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">447</entry><entry namest="col4" nameend="col4" align="right">25</entry></row><row><entry namest="col1" nameend="col1" align="right">23</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">432</entry><entry namest="col4" nameend="col4" align="right">4</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 5</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">434</entry><entry namest="col4" nameend="col4" align="right">63</entry></row><row><entry namest="col1" nameend="col1" align="left">Control 6</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">447</entry><entry namest="col4" nameend="col4" align="right">43</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Control 7</entry><entry namest="col2" nameend="col2" align="right">7</entry><entry namest="col3" nameend="col3" align="right">439</entry><entry namest="col4" nameend="col4" align="right">46</entry></row></tbody></tgroup></table></tables>

The above results indicate that the yellow dyes according to the invention has improved light stability in comparison to various control yellow dyes. <chemistry id="chem0004" num="0004"><img file="EP0332924A2_D0007.tif" /></chemistry>

[Artisil Foron 6GFL® (Sandoz Corp.)]