JPH053398B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a tricyano-based thermal transfer recording dye. Currently, a dye sublimation thermal transfer recording method has been proposed as a method for obtaining color hard copies from televisions, CRT color displays, color facsimile machines, magnetic cameras, etc. In this method, a transfer sheet coated with a sublimable dye is heated with a heat-sensitive recording head to sublimate and transfer the dye to the recording medium to obtain color recording. Since the amount of sublimation can be controlled, it is easy to express gradation, and compared to other recording methods, it is especially advantageous for obtaining full-color hard copies. By the way, the dye used in this recording method must meet the following conditions. Easily sublimated under the operating conditions of a thermal recording head. Do not thermally decompose under the operating conditions of the thermal recording head. Must have a favorable hue in terms of color reproduction. High molecular extinction coefficient. Stable against light, moisture, chemicals, etc. Easy to synthesize. The object of the present invention is to provide a magenta dye that satisfies the above-mentioned requirements for a dye used in the heat-sensitive recording method. That is, the present invention has the following general formula [] (In the formula, R ¹ and R ² are a lower alkyl group, an aralkyl group, an aryl group, a cyclohexyl group, a halogeno lower alkyl group, a lower alkoxy lower alkyl group,
lower alkoxy lower alkoxy lower alkyl group,
Hydroxy lower alkyl group, tetrahydrofurfuryl group, aralkyloxy lower alkyl group, aryloxy lower alkyl group, alkenyloxy lower alkyl group, tetrahydrofurfuryloxy lower alkyl group, lower alkoxycarbonyl lower alkyl group, lower alkylcarbonyloxy lower alkyl group , lower alkoxycarbonyloxy lower alkyl group. However, R ¹ and R ² do not have a lower alkyl group at the same time. ) The gist is a tricyano-based thermal transfer recording dye shown in the following. R ¹ and R ² in the above general formula [ ] are lower alkyl groups such as methyl group, ethyl group, linear or branched propyl group, butyl group; phenethyl group, benzyl group, phenylpropyl group Aralkyl groups such as phenyl group, p-chlorophenyl group; cyclohexyl group; lower alkoxy lower alkyl groups such as methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, γ-methoxybutyl group; Lower alkoxy lower alkoxy lower alkyl groups such as methoxyethoxyethyl group, ethoxyethoxyethyl group, propoxyethoxyethyl group; hydroxy lower alkyl groups such as hydroxyethyl group, β-hydroxypropyl group, β-hydroxybutyl group; chloroethyl group, chloro propyl group, promoethyl group,
Halogeno lower alkyl groups such as iodoethyl group; cyanomethyl group, tetrahydrofurfuryl group; alkenyloxy lower alkyl group such as allyloxyethyl group, 2-methylallyloxyethyl group; phenyloxyethyl group, p-chlorophenyloxyethyl group Aryloxy lower alkyl groups such as benzyloxyethyl group, phenethyloxyethyl group; methoxycarbonylethyl group, ethoxycarbonylethyl group, propoxycarbonylethyl group, methoxycarbonylmethyl group, ethoxycarbonylmethyl group lower alkoxycarbonyl lower alkyl groups such as groups; lower alkylcarbonyloxy lower alkyl groups such as acetoxyethyl group, propionyloxyethyl group, β-acetoxypropyl group, β-acetoxybutyl group; methoxycarbonyloxyethyl group; ethoxycarbonyloxyethyl Lower alkoxycarbonyloxy lower alkyl groups such as groups;
Examples include tetrahydrofurfuryloxy lower alkyl groups such as tetrahydrofurfuryloxyethyl group. Particularly preferable R ¹ and R ² are C _1-4 alkyl groups,
Phenethyl group, γ-methoxybutyl group, chloroethyl group, benzyl group, methoxyethyl group, methoxyethoxyethyl group, tetrahydrofurfuryl group, phenyl group, cyclohexyl group, phenethyloxyethyl group, phenoxyethyl group, allyloxyethyl group, Examples include a tetrahydrofurfuryloxyethyl group, a hydroxyethyl group, a methoxycarbonylethyl group, and an acetoxyethyl group. In the present invention, magenta dye generally has a visible absorption spectrum of about 510 to 560 nm.
A dye that has an absorption band with a maximum value in the range of m and has no absorption band in other wavelength ranges. As a method for producing the dye of the present invention, the following general formula [] (In the formula, R ¹ and R ² have the same meanings as in the above general formula [].) The aniline represented by the formula is reacted with tetracyanoethylene in an organic solvent, and the target product precipitated after the reaction is filtered. It can be easily obtained by If the target product does not precipitate after the reaction, the target product can be precipitated by adding a solvent or water that has low solubility to the target product.
Furthermore, the target product can be purified by conventional means such as recrystallization or column chromatography, if necessary. As a method for producing a thermal transfer recording ink using the dye of the present invention, the dye may be mixed with a suitable resin, solvent, water, etc. to prepare the recording ink. In the thermal transfer method, the ink obtained above is applied onto a suitable base material to create a transfer sheet, the sheet is placed on the recording medium, and then heated and pressed from the back side of the sheet using a thermal recording head. In this way, the dye on the sheet is transferred onto the recording medium. As the resin for preparing the above ink,
Those used in ordinary printing inks may be used, such as oil-based resins such as rosin-based, phenol-based, xylene-based, petroleum-based, vinyl-based, polyamide-based, alkyd-based, nitrocellulose-based, alkyl cellulose, or maleic resins. Acid-based,
Water-based resins such as acrylic acid, casein, Sierra, and glue can be used. In addition, as a solvent for ink preparation, methanol, ethanol,
Alcohols such as propanol and butanol,
Cellosolves such as methyl cellosolve and ethyl cellosolve, aromatics such as benzene, toluene and xylene, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, hydrocarbons such as ligroin, cyclohexane and kerosene. When using an aqueous resin, water or a mixture of water and the above-mentioned solvents can be used. Substrates for applying ink include condenser paper, thin paper such as glassine paper, polyester,
A plastic film having good heat resistance such as polyamide or polyimide is suitable, and the thickness of these base materials is suitably about 5 to 50 .mu.m in order to improve the efficiency of heat transfer from the heat-sensitive recording head to the dye. Plain paper can also be used as the recording medium, but in order to improve the color development of the dye, it may be coated or impregnated with a resin that is compatible with the dye, or it may be laminated with a resin film. Good recording can be achieved by using paper or special processed paper that has been treated with acetylation.
It is also possible to use films of various resins or synthetic papers made from them. Furthermore, by hot-pressing and laminating, for example, a polyester film on the transfer recording surface after transfer recording, it is possible to improve the color development of the dye and to stabilize the recording during storage. Since the dye of the present invention has a clear magenta color, for example, the structural formula is as follows: The yellow pigment represented by and the structural formula below Suitable for obtaining full color in combination with cyan dye represented by The above yellow dye can be easily obtained by diazotizing aniline and N-methyl-3-cyano-4-methyl-6-hydroxy-2-pyridone. Further, the above cyan dye can be obtained by reacting 1-amino-2-carboxy-4-methylaminoanthraquinone with methanol in concentrated sulfuric acid. EXAMPLES The present invention will be specifically explained below with reference to Examples, but these Examples are not intended to limit the present invention. Example 1 (i) Production of dye 8.4 g of N-ethyl-N-phenethylaniline
was added to 15 ml of N,N-dimethylformamide, and 3.84 g of tetracyanoethylene was added thereto. After reacting at about 50°C for 1 hour, the reaction solution was cooled to room temperature, 60 ml of methanol was added, and the precipitated dark The red crystals were filtered, washed with methanol and water, and dried to obtain 8.8 g of a dye having the following structural formula. The melting point of this dye was 124-126°C, and the mass spectrum showed a parent ion peak of m/e=326. In addition, the visible absorption spectrum in chloroform showed a maximum absorption value at 526 nm. (ii) Preparation method of thermal transfer recording ink 2 g of the dye obtained in the above (i) 8 g of ethyl cellulose 90 g of isopropanol Total 100 g The dye mixture of the above composition was mixed for about 30 minutes with a paint conditioner using glass beads. The ink was prepared by: (iii) Method for creating a transfer sheet The above ink was applied to a capacitor paper (10 μm) using a gravure proofing machine (plate depth 30 μm). (iv) Method for preparing image receiving paper Aqueous dispersion of 34% by weight of saturated polyester (Vylonal MD-1200 manufactured by Toyobo Co., Ltd.) 10
g and 50 g of 50% by weight water slurry of calcium bicarbonate (Maruo Calcium Manufacturing Super 1500) and coated the prepared paint on high-quality paper (thickness 200 μm) using a bar coater (RK Print Coat Instruments).
No. 5) manufactured by Co., Ltd. (v) Transfer recording method The ink-coated surface of the transfer sheet is placed on the paint-coated surface of the image-receiving paper, and thermal transfer recording is performed using a thermal head having a 250Ω heating resistor at a density of 4 dots/〓 to obtain a color density of 1.20. A record of magenta color was obtained. At this time, a voltage of 18V was applied to the heat-sensitive head for 6 milliseconds. The color density is measured using a densitometer RD-514 model manufactured by Macbeth Co., Ltd. (filter: RATSUTEN).
No. 58). Color density was calculated using the following formula. Color density = log ₁₀ (Io/I) Io: Intensity of reflected light from a standard white reflector I: Intensity of reflected light from a test object In addition, the light resistance test of the obtained record was performed using a carbon arc fade meter. (manufactured by Suga Test Instruments)
(Black panel temperature 63±2℃)
However, there was almost no discoloration after 40 hours of irradiation. Example 2 Using 2 g of the pigment shown in Table 1, ink was prepared, a transfer sheet and image receiving paper were created, and transfer recording was performed in the same manner as in Example 1, and magenta colors with the color densities shown in Table 1 were obtained. Obtained a record of. All of these records showed almost no discoloration when tested for light resistance in the same manner as in Example 1.

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[Table] * Maximum absorption wavelength indicates the value measured in chloroform.

Claims (1)

[Claims] 1. General formula [] (In the formula, R ¹ and R ² are a lower alkyl group, an aralkyl group, an aryl group, a cyclohexyl group, a halogeno lower alkyl group, a lower alkoxy lower alkyl group,
lower alkoxy lower alkoxy lower alkyl group,
Hydroxy lower alkyl group, tetrahydrofurfuryl group, aralkyloxy lower alkyl group, aryloxy lower alkyl group, alkenyloxy lower alkyl group, tetrahydrofurfuryloxy lower alkyl group, lower alkoxycarbonyl lower alkyl group, lower alkylcarbonyloxy lower alkyl group , lower alkoxycarbonyloxy lower alkyl group. However, R ¹ and R ² do not have a lower alkyl group at the same time. ) Tricyano-based magenta dye for thermal transfer recording.