JPH0517037B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION This invention relates to dye-donor elements used in laser-induced thermal dye transfer, and more particularly to the use of certain infrared absorbing cyanine dyes. In recent years, thermal transfer systems have been developed for obtaining prints from images formed electronically with color video cameras. According to one method of obtaining such prints, the electronic image is first color separated using color filters. Next, each color-separated image is converted into an electrical signal. These signals are subsequently manipulated to generate cyan, magenta and yellow electrical signals. These signals are then transmitted to a thermal printer. To obtain a print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. Subsequently, both are inserted between the thermal printing head and the platen roller. Heat the dye-donor sheet from the back side using line-type thermal printing. The thermal printing head has multiple heating elements and is heated sequentially in response to cyan, magenta and yellow signals. Repeat this process with the other two colors. In this way a color hard copy is obtained which corresponds to the original image seen on the screen. A more detailed description of this process and the apparatus for carrying it out is found in Brownstein, U.S. Pat. has been done. An alternative method of obtaining a thermal print using the aforementioned electrical signals is to use a laser instead of a thermal printing head. In this system, the donor sheet is
Contains materials that strongly absorb at laser wavelengths. When the donor is irradiated, the absorbing material converts light energy into thermal energy and transfers the heat to the nearby dye, heating it to its vaporization temperature for transfer to the receiver. This absorbent material is layered below and/or mixed with the dye. The laser beam is modulated with electrical signals representing the shape and color of the original image, and the dye is heated and vaporized only in the areas needed to be present on the receptor to reconstruct the original object color. A more detailed explanation of this process can be found in GB2083726A. BACKGROUND OF THE INVENTION The absorbent material disclosed in GB2083726A for its laser system is carbon. PROBLEM SOLVED BY THE INVENTION The problem with using carbon as an absorbent material is that carbon is particulate and has a tendency to agglomerate when coated, which reduces the quality of the transferred dye image. It's about letting people know. Carbon also migrates to the receptor by sticking or ablation, causing color images to become mottled or desaturated. One aim of the present invention is to find absorbent materials that do not have these drawbacks. (Means for Solving the Problems) The above and other objects are achieved by the present invention relating to the following. That is, in the present invention, the dye layer is made of an infrared absorbing material, and the infrared absorbing material has the following formula: characterized by being a cyanine dye having
Dye-donor element for laser-induced thermal dye transfer. However, in the above formula, R ¹ and r ² are each independently substituted or unsubstituted alkyl gas, such as -CH ₃ , -
C ₂ H ₅ −(CH ₂ ) ₂ −OCH ₃ , −(CH ₂ ) ₃ CO ₂ CH ₃ , −
C ₃ H ₇ , -C ₄ H ₉ , or -(CH ₂ ) ₃ Cl; R ³ , R ^{4 and} R ⁵ are each independently hydrogen or a substituted or unsubstituted alkyl group, e.g. represents the point made regarding ² ; or
R ³ and R ⁴ are bonded to each other directly or via one or more methine groups or methylene groups, and are 5- to 9-membered substituted or unsubstituted rings, such as

【formula】

【formula】

[Formula] may be formed; Z ¹ and Z ² each independently represent hydrogen or an atom necessary for forming an unsubstituted or substituted benzene ring or naphthalene ring; Y ¹ and Y ² each independently represent Alkyl substituted carbon atoms such _as -C( _CH3 ) _2- or -C( _C2H5 ) ₂
-; represents a vinylene group, an oxygen atom, a sulfur atom, a selenium atom, or a nitrogen atom to which R ¹ or a substituent or unsubstituted aryl group is bonded; J is hydrogen; a substituted or unsubstituted alkyl group is replaced with R ¹ Pointed out regarding R ² ; substituted or unsubstituted aryl groups e.g.

【formula】

【formula】

[Formula] A halogen atom; or a nitrogen atom substituted with an alkyl or aryl group, or an atom necessary to form a 5- or 6-membered heterocycle, e.g.

【formula】

【formula】

【formula】

[Formula] represents; n is 0 or 1; and X is a monovalent anion such as I, BF ₄ ,
ClO ₄ , PF ₆ , or Br . One preferred embodiment of the invention is that R ¹ and R ² are both methyl and J is hydrogen. In another preferred embodiment, R ³ and R ⁴ are joined together to form a 6-membered ring. In yet another preferred embodiment,
Both Z ¹ and Z ² represent atoms necessary for forming a benzene ring substituted with a nitro, halo or cyano group. In yet another preferred embodiment, Y ¹ and Y ²
Both represent a dialkyl-substituted carbon atom. The infrared absorbing dyes described above may be used in any concentration that is effective for the intended purpose. In general, good results have been obtained when used at concentrations of 0.04 to 0.5 g/m ² in the dye layer itself or in adjacent layers. Spacer beads may be used as a separating layer on the dye layer to separate the dye donor from the dye receiver, thereby increasing the uniformity and density of dye transfer. This invention is described in more detail in DeBoer, US Patent Application No. 136,073, filed Dec. 21, 1987, titled "Spacer Bead Layers for Dye-Donor Elements for Laser-Induced Thermal Dye Transfer." If desired, the spacer beads may be coated with a polymeric binder. Dyes within the scope of this invention include: The dye used in the dye layer of the dye-donor element of this invention can be any dye that is transferable to the dye-receiving layer by the action of heat. Particularly good results have been obtained using the following sublimable dyes. or any of the dyes disclosed in U.S. Pat. No. 4,541,830. The dyes mentioned above may be used alone or in combination to obtain monochromes. The dye is
It is used in a coating weight of 0.05 to 1 g/m ² and preferably hydrophobic. The dye in the dye-donor element may be a cellulose derivative such as cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate; polycarbonate; styrene-acrylonitrile copolymer, polysulfone or polyphenylene oxide. dispersed in a polymeric binder. Binder: 0.1 to 5g/m ²
used with a coverage of The dye layer of the dye-donor element may be coated onto the support or printed onto the support by printing techniques such as gravure. Any material that is dimensionally stable and capable of withstanding the heat generated by the laser beam can be used as the support for the dye-donor element of the present invention. Such materials include polyesters such as polyethylene terephthalate; polyamides; polycarbonates; glassine paper; capacitor paper; cellulose esters; fluoropolymers; polyethers; polyacetals; or polyolefins. The thickness of the support is generally between 2 and 250 μm. If desired, the support may be coated with a subbing layer. Dye-receiving elements used with the dye-donor elements of the present invention usually consist of a support with a dye image-receiving layer on top. The support may be a transparent film such as polyethylene terephthalate, or a reflective film such as white polyester (polyester doped with white pigment). The dye image-receiving layer consists of, for example, polycarbonate, polyurethane, polyester, polyvinyl chloride, styrene-acrylonitrile copolymer, polycaprolactone or mixtures thereof. The dye image-receiving layer may be present in any amount effective for the initial purpose. Good results have generally been obtained with concentrations of 1 to 5 g/cm ² . As mentioned above, the dye-donor elements of the present invention are used in forming dye transfer images. Such a process consists of imagewise heating the dye-donor element as described above using a laser and transferring the dye image to the dye-receiving element to form a dye transfer image. The dye-donor elements of this invention are used in sheet form or as a continuous roll or ribbon. When using continuous rolls or ribbons,
It may have only one type of dye or it may have alternating regions of different dyes such as sublimable cyan and/or magenta and/or yellow and/or black and other dyes. Such dyes are covered by U.S. Patent No.
No. 4541830; No. 4698651; No. 4695287; and No. 4701439. That is,
Single, two, three, or four color elements (or even multicolor elements) are included within the scope of this invention. In one preferred embodiment of the invention, the dye-donor element comprises a polyethylene terephthalate support coated with successive regions of cyan, magenta and yellow dyes, and the process steps are carried out sequentially for each color. to form a three-color dye transfer image. Of course, when this process is performed in a single color, a monochrome dye transfer image is obtained. Thermal transfer of the dye from the donor sheet to the receiver can be accomplished using ion gas lasers such as argon or krypton, metal vapor lasers such as copper, gold and cadmium, solid state lasers such as ruby or YAG, or
Several types of lasers could probably be used, including diode lasers such as gallium-arsenide, which emit in the infrared between 750 and 870 nm. However, in practice, diode lasers are advantageous due to their small size, low cost, stability, reliability, durability and ease of modulation. In fact, for a laser to be used to heat a dye-donor element, the laser radiation must be absorbed by the dye layer and converted into heat by a molecular process known as internal conversion. That is, useful dye layer configurations will be related not only to the hue, sublimability, and intensity of the image dye, but also to the ability of the dye layer to absorb radiation and convert it to heat. Lasers that can be used to transfer dye from the dye-donor elements of this invention are commercially available. For example, Spectrodiode Labs' laser model SDL−
2420−H2 or Sony laser model SLD−
304v/w is available. Examples To illustrate the invention, the following examples are presented. Example 1 Magenta dye donor Cellulose acetate propionate binder (acetyl
A layer containing the magenta dye (0.38 g/m ^{2 )} and infrared absorbing dye compound 1 (0.14 g/m 2 ) in 2.5% propionyl (propionyl 45%) (0.27 g/m ² ) is formed by combining cyclosexanone and butanone. Dye-donor elements of the invention were prepared by coating a 100 μm thick unprimed polyethylene terephthalate support from a mixed solvent. This dye layer was overcoated with polystyrene beads (average diameter 8 μm) (0.02 g/m ² ) from an aqueous solution as described in the aforementioned DeBoer US Patent Application No. 136,073. A control dye-donor element was prepared as described above except that the magenta imaging paint was omitted. Control dye below (infrared non-absorbing cyanine dye)
A second control dye-donor element was prepared as described above on a 75 μm thick polyethylene terephthalate support subbed with gelatin containing 0.32 g/m ² . control dye; Increase magenta dye to 0.45g/m ² and replace infrared absorbing dye with carbon dispersion (0.60g/m ² );
and cellulose acetate propionate binder (0.50
A ^third control dye-donor element was prepared in the same manner as the second control element except that it was coated from a mixed solvent of toluene and tedrahydrofuran. A solution of Bayer AG's Makrolon 5707 bisphenol A-polycarbonate resin in a methylene chloride-trichloroethylene mixed solvent containing titanium dioxide was used.
A dye-receiving element was prepared by coating on a 175 μm polyethylene terephthalate support. The dye donor placed on the drum was superimposed on the receiver and the surface beads were taped with just enough tension to cause deformation. Next, this assembly
Focused on a drum rotating at 180 rpm
Exposure to an 830 nm laser beam transferred the dye area to the receiver. The laser beam was generated from a Spectrodiode Labs laser model SDL-2420-H2.
The spot diameter was 50 μm and the exposure time was 5 milliseconds. The power level was 86 milliwatts and the exposed energy was 44 microwatts per square micron. The observation results of the images formed on each receptor were as follows. The dye-donor element containing Compound 1 produced a bright magenta image on the receiver with no visible color stain from the cyanine dye. The status A green reflection density was 2.3. A first control dye-donor element containing only cyanine dye and no magenta imaging dye was
No visible image was formed on the receptor. The second control dye-donor element also did not form a visible image, probably because this dye has a λmax of 600 nm and therefore does not absorb much at 830 nm. A third control dye-donor element containing carbon as the absorbing material formed an image, but its Status A reflection density was only 1.2. The image had a mottled appearance, probably due to agglomeration of the carbon dispersion during the drying process. Carbon speckles were also observed in the receptor transcription. Example 2 Cyan dye donor Cellulose acetate propionate binder (acetyl
A layer containing the above cyan dye (0.40 g/m ^{2 )} and infrared absorbing dye compound 2 (0.14 g/m ² ) in cyclohexanone and butanone (2.5%, propionyl 45%) (0.20 g/m 2 ) 100μ thick from a mixed solvent with
Dye-donor elements of the invention were prepared by coating an unsubbed polyethylene terephthalate support of 1. On this dye layer, as in Example 1, polystyrene beads (average diameter 8 μm) (0.02 g/m ² ) were overcoated from an aqueous solution. A control dye-donor element was prepared as described above except that the infrared absorbing paint was omitted. A dye-receiving element was prepared and processed as in Example 1. The observation results of the images formed on each receptor were as follows. That is, the dye-donor element containing Compound 2 formed a homogeneous cyan image on the receiver with a density of 0.7. Also, the control dye-donor element did not form any visible image on the receiver. Example 3 Cyan Dye Donor - Positive Screen Imaging The above cyan dye (0.38 g/m ² ), infrared absorbing dye compounds 1, 3, 5 and 10 in cellulose nitrate binder (0.89 g/m ² ) (0.13 g/m ² ) and a hindered amine stabilizer, CIBA-Geigy's Tinubin 770, was not primed to a thickness of 100 μm from a mixed solvent of dimethylformamide and butanone. Dye donors of the invention were prepared by coating on polyethylene terephthalate supports. This dye layer was overcoated with polystyrene beads (average diameter 8 μm) (0.22 g/m ² ) as described in the aforementioned DeBoer US Patent Application No. 136,073. A control dye-donor coating was prepared as described above except that the cyanine infrared absorbing paint was omitted. A paint receiver was prepared and treated in the same manner as in Example 1, except that the drum rotation speed was 120 rpm. Receptor Status A measured red reflex density. As shown in Table 1, except for the 0.2 concentration control, the concentration of the dye donor with added cyanine dye was
It became 0.5 or more. In a second variant to demonstrate positive imaging,
First, the Status A red transmission density of the paint donor was measured. Evaluations were made as described above, except that no dye receiver was used, but instead a stream of air was blown over the donor surface to remove the sublimated dye.
The Status A red density of the original dye donor was compared to the residual density after laser sublimation and removal of the cyan image dye. When the cyanine dye of the present invention was present, all concentrations decreased to below 1.0. This shows that the cyanine dye of the present invention is effective in forming positive images.

[Table] Example 4 Magenta dye donor Control donor prepared in the same manner as above except that the magenta dye was used (0.38 g/m ² ), the stabilizer was omitted, and compounds 9, 11 and 12 were used. A coating was produced. A dye receptor was prepared and treated in the same manner as in Example 1, and the Status A green reflection density of the receptor was measured. The results were as follows. Table 2 Status A Green Density in Donor Infrared Dye None Transferred to Receiver (Control) 0.0 Compound 9 0.1 Compound 11 0.6 Compound 12 0.4 The above results are consistent with the results obtained for coatings containing infrared-absorbing cyanine dyes. All are shown to give substantially higher concentrations than the control. Advantages of the Invention Use of the present invention provides an absorbent material that does not agglomerate and degrade transferred dye images when coated.

Claims (1)

[Scope of Claims] 1. A dye-donating element comprising a support and a dye layer provided on the support and comprising a polymer binder, a sublimable dye, and an infrared absorbing substance, the polymer binder and the The infrared absorbing material is virtually immobilized by laser-induced heat;
A dye-donating element for laser-induced thermal transfer, characterized in that the infrared absorbing substance is a cyanine dye represented by the following structural formula. However, in the above formula, R ¹ and R ² each independently represent a substituted or unsubstituted C ₁ to C 6 alkyl group; R ³ , R ⁴ and R ⁵ each independently represent hydrogen or a substituted or unsubstituted C 1 to C ₆ alkyl group; ₁ -C ₆ represents an alkyl group; or R ³ and R ⁴ are bonded directly or bonded to each other via one or more methine groups or methylene groups to form a 5- to 9-membered substituted or unsubstituted ring; Z ¹ and Z ² each independently represent hydrogen or multiple atoms necessary to form a substituted or unsubstituted benzene ring or naphthalene ring; Y ¹ and Y ² each independently represent Represents a dialkyl-substituted carbon atom, vinylene group, oxygen atom, sulfur atom, selenium atom, or a nitrogen atom to which the above R ¹ or a substituted or unsubstituted aryl group is bonded; J is hydrogen; substituted or unsubstituted C ₁ to C ₆ alkyl group; a substituted or unsubstituted C ₁ to C ₁₀ aryl group; a halogen atom; or a nitrogen atom substituted with an alkyl group or an aryl group, or to form a 5-membered or 6-membered ring. and X is a monovalent anion.