JPH05185752A - Dye for thermal transfer recording and transfer sheet containing the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a compounded black dye having various advantages for a transfer sheet. [Structure] General Formula (1) embedded image Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃
An orange dye represented by (1) and a general formula (2): At least one of the blue dyes represented by

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a black dye for heat-sensitive transfer recording and a heat-sensitive transfer sheet containing the same.

The present invention also provides a blue dye for thermal transfer recording,
Particularly, it relates to a blue dye useful as a blue component of a blended black dye used for black recording.

[0003]

2. Description of the Related Art In a thermal transfer system, a thermal transfer sheet coated with an ink containing a dye for sublimation thermal transfer is superposed on a recording material (image receiving paper) and heated and pressed by a thermal recording head to sublimate the dye to receive an image. This is a method of transferring to paper and obtaining a full-color copy with good gradation.

The first characteristic of the thermal recording system is that the thermal recording head is mainly used as a hardware device, and it is compact and excellent in maintainability and reliability. Secondly, since it is possible to obtain a mixed color image at the molecular level, it is possible to obtain a recording similar to a silver salt color photograph having excellent gradation and reproducibility.

Furthermore, this system has been applied as a wide variety of full-color recording systems such as CG (computer graphic), plate making system, video movie and still video system, and prepaid card, and has recently attracted particular attention.

More specifically, by heating a transfer sheet coated with a sublimable dye by a thermal recording head controlled by color signals of a still image, the dye is transferred to an image receiving paper, and recording is performed by the transfer. is there. Usually, three primary colors of yellow, magenta, and cyan are used as the dye for the transfer sheet. Further, in order to obtain a precise image for commercial use, black is added to the above three primary colors to add light and dark, and four primary colors are used.

The conditions required for a black type heat-sensitive transfer sheet are as follows.

Good compatibility or solubility of the dye with the solvent and the binder resin in the ink used for coating the transfer sheet.

The heat energy for sublimation dyeing from the transfer sheet to the image receiving paper is as low as possible, and an image having a color value is transferred to the image receiving paper.

400-700n of transferred black image
The transmittance curve in the m range is flat.

The dye in the transfer sheet should not recrystallize even in a heated or humidified state.

The transferred image has good light resistance and storage stability.

The black matrix dyes should be similar in gradation to each other.

Among the above-mentioned conditions, the following conditions are particularly required: the solubility in the solvent in the ink is large, and the compatibility with the binder resin is good.

That is, in the thermal transfer system, since the dye sublimes at the molecular level, the dye must be completely dissolved in the binder resin on the transfer sheet. If the dye is transferred in a state of being insoluble in the binder resin on the transfer sheet, a uniform image cannot be obtained, the image density is low, and the commercial value is extremely poor.

Development is progressing so as to satisfy all the above-mentioned conditions required for the transfer sheet, and at present, it is attempted to satisfy the conditions by blending a plurality of sublimable dyes. Further, in order to obtain good gradation, that is, in order to satisfy the condition, various mother dyes having similar gradation to each other have been studied as black compounding pigments. But,
A black transfer recording dye satisfying all of the above conditions has not yet been developed, and further improvement is required.

On the other hand, conventionally proposed azo blue dyes generally have a high molar extinction coefficient, so that many of them potentially have a dye concentration required for a transferred image. However, on the other hand, there is a problem that the dye crystallizes on the transfer sheet due to insufficient solubility or poor compatibility with the binder resin, and the thermal transfer efficiency of the dye is significantly impaired, or after transfer, the dye for the image receiving paper The dyeing power is insufficient and the image on the image-receiving paper is touched by stains on the image itself, or the quality of the image itself is deteriorated. Further, the durability of the dye itself, which is the most important, is particularly poor with respect to light resistance. In many cases, there were problems that could not be preserved, and dyes that solved all these problems were extremely few.

[0018]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and developed a black compounded dye and a transfer sheet containing the same that satisfy all of the above-mentioned conditions, Completed the invention.

[0019]

The present invention for solving the above-mentioned problems is based on the general formula (1)

[0020]

Embedded image Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃ (1) [wherein Ar ₁ , Ar ₂ and Ar ₃ are each independently,
The aryl group which may have a substituent is shown. ] An orange dye represented by the general formula (2)

[0021]

[Chemical 4] [In the formula, R ₁ , R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, a nitro group, a hydroxy group, an alkyl group which may have a substituent, an alkoxy group, an alkylsulfonylamino group or an alkylcarbonyl group. It represents an amino group, and R ₄ and R ₅ each independently represent an alkyl group which may have a substituent. ] In a thermal transfer recording black dye containing one or more, respectively blue dye represented, blue dye, in the general formula (2), R ₁ is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a nitro group And R ₂ and R ₃ each independently or independently represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylcarbonylamino group or an alkylsulfonylamino group, and R ₄ represents an alkyl group which may have a substituent, Represents an aralkyl group or an alkylcarboxyethyl group,
R ₅ includes a group represented by an alkoxycarbonylethyl group.

In the general formula (2), the present invention provides R
₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a nitro group, and R ₂ and R ₃ each independently or independently represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylcarbonylamino group or an alkylsulfonylamino group. , R ₄ represents an alkyl group which may have a substituent, an aralkyl group or an alkylcarboxyethyl group, and R ₅ represents an alkoxycarbonylethyl group,
Blue dye for sublimation heat transfer recording.

Further, the present invention is a heat-sensitive transfer sheet containing the black dye.

The present invention will be described in detail below.

In the present invention, as described above, the compound (1) and the compound (2) are each mixed in one kind or more, and by using the compound as a black dye, surprisingly, all the above conditions (1) to (4) are satisfied. It was completed by finding that a transfer sheet can be obtained.

Further, the above black pigment is added in an amount of 500 to 550n.
The absorption curve is further flattened by adding a red heat-sensitive transfer dye that absorbs light having a wavelength near m.

The color tone and spectral characteristics required for the black colorant in the present invention are completely different from those of the other three primary colors (yellow, magenta and cyan).

The spectral characteristics required for the dyes of the three primary colors yellow, magenta, and cyan are that they have a sharp absorption curve centered on the maximum absorption wavelength.

On the other hand, the black pigment of the present invention is 4
It has a near-flat absorption curve for light in the visible region of 00 to 700 nm.

A black transfer image by a transfer sheet using clear three primary colors is 400 to 700 n especially in the case of a light color.
The shape of the absorption curve in the visible part of m becomes uneven. As a result, when the light source is different, for example, reddish, greenish, and bluish black is produced, and in extreme cases, the color tone may not be recognized as black, and there is a problem in color rendering properties.
In other words, it is difficult to obtain black with high color rendering using the three primary colors.

Furthermore, it is necessary to select each of the black colorants to be blended that have similar sublimation properties. The reason is that, if each of the compounded dyes has different sublimation property, the image density of each dye is different with respect to the applied heat energy, resulting in different tone of light color and dark color.

Therefore, the present invention is completed by blending the compounds of the general formulas (1) and (2) satisfying all the conditions of as a dye for thermal sublimation transfer for black. More preferably, a red dye having the absorption region of 500 to 550 nm which is the boundary region of the absorption wavelength regions of the compounds of the general formulas (1) and (2) and satisfying the conditions up to is used as the black dye. It is desirable to add.

The following general formula (1) used in the present invention

[0034]

Embedded image In the compound of Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃ (1), Ar ₁ , Ar ₂ and Ar ₃ each represent an aryl group and may have a substituent. Good. As the substituent, an alkyl group having 1 to 4 carbon atoms, a halogen atom such as a chlorine atom, a nitro group, a hydroxy group and the like are preferable.

Specific examples of the dye of the general formula (1) include the following.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3] The following general formula (2) used in the present invention

[0039]

[Chemical 6] In the compound of, specific examples of R ₁ include a hydrogen atom,
The number of carbon atoms of chlorine atom, bromine atom, halogen atom such as fluorine, alkyl group such as methyl group, ethyl group, propyl group, isopropyl group, alkoxy group such as methoxy group, ethoxy group, propoxy group, hydroxyl group and alkyl group 1 to
There are 4 alkylcarbonylamino groups, C 1-4 alkylsulfonylamino groups, and nitro groups.

Specific examples of R ₂ and R ₃ are the same or independently, a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group and an isopropyl group, a methoxy group,
Alkoxy group such as ethoxy group and propoxy group, acetylamino group, ethylcarbonylamino group, alkylcarbonylamino group such as n-propylcarbonylamino group, methylsulfonylamino group, ethylsulfonylamino group,
Examples thereof include alkylsulfonylamino groups such as n-propylsulfonylamino group.

Specific examples of R ₄ include an alkyl group which may have a substituent such as a methyl group, an ethyl group, a butyl group, a 2-hydroxyethyl group, a 2-cyanoethyl group and a 4-cyanobutyl group, and benzyl. Group, phenethyl group, aralkyl group such as P-methylbenzyl group and P-ethoxyphenethyl group, and alkylcarboxyethyl group such as methylcarboxyethyl group, ethylcarboxyethyl group and isopropylcarboxyethyl group.

A specific example of R ₅ is an alkoxycarbonylethyl group having an alkyl group having 1 to 4 carbon atoms.

Specific examples of the dye of the general formula (2) include the following.

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

[Table 7] The following azo dyes are preferable as the red dye used to make the absorption curve flatter, but the dyes are not limited to these dyes.

[0048]

[Table 8]

[0049]

[Table 9] The dye represented by the general formula (2) of the present invention is
It can be easily obtained by diazotizing an -amino-benzisothiazole compound and performing a coupling reaction with various anilines.

The dye represented by the general formula (1) is a known compound and is generally commercially available.

Furthermore, when a black dye for transfer recording is obtained using the compounds represented by these (1) and (2), the compounding weight ratio thereof is (1) :( 2) = 2: 8 to 4: 6. It is preferable that

The blending weight ratio of the red dye used for flattening the absorption curve is preferably 0 to 30 weight based on 100 weight of the total of the compounds represented by (1) and (2).

According to the research conducted by the present inventors, the light fastness of an image formed by transfer with this printing system, that is, the light fastness of a dye when dyed on the image receiving paper side is the same, It has been found that the end group may greatly influence.

For example, by comparing the terminal groups X, Y and Z of the compound of the following general formula (2 ′), the tendency of light resistance becomes clear.

[0055]

[Chemical 7] In other words, X and Y are improved in light resistance in the order of alkyl group <alkoxyalkoxy group <halogenoalkyl group <cyanoalkyl group <alkylcarbonyloxyalkyl group,
It has been clarified that the light resistance is highest when both X and Y are alkylcarbonyloxyalkyl groups.

Table 10 shows specific examples thereof. Here, the light resistance is 120 using a xenon fade meter.
The residual rate of color density when irradiated with light having an energy of KJ / cm ² is shown.

[0057]

[Table 10] Furthermore, the compound (2) is also excellent in solubility in a solvent and a binder resin, and no crystallization of the dye is observed after the transfer ribbon is produced. Therefore, it is possible to obtain a clear image with a transfer density which does not change even after long-term storage. It is clear from Table 11 that this is also the effect of the terminal group. Here, the solubility in a 1: 1 mixed solution of toluene and methyl ethyl ketone and the ribbon storage stability were measured using the compound of the general formula (2).

[0058]

[Table 11] The storage stability of the ribbon is evaluated by observing with an optical microscope the condition after leaving it for 2 weeks at room temperature, and it is judged by the degree of crystallization of the dye. The sample was evaluated as Δ, and when complete crystallization was confirmed, it was evaluated as ×.

It can be seen that the compound having an alkylcarbonyloxyalkyl group as the terminal group, such as the compound (2), is very excellent in solubility and ribbon storage stability. As described above, the compound (2) is particularly suitable as a blue dye for forming a full color having a good light resistance and solubility, a high transfer rate, a clear color and a low turbidity.

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 binder resin, a solvent and the like to prepare the recording ink.

The amount of the dye in the thermal transfer recording ink is usually 5 to 10% by weight.

The binder resin for preparing the above-mentioned ink may be one used in ordinary printing inks, such as rosin type, phenol type, xylene type, petroleum type, vinyl type, polyamide type, alkyd type and nitro type. Oily resins such as cellulose-based and alkyl celluloses, or aqueous resins such as maleic acid-based, acrylic acid-based, casein, shellac and glue can be used.

Further, as a solvent for preparing the ink,
Alcohols such as methanol, ethanol, 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, acetone, methyl ethyl ketone, cyclohexanone, etc. The above ketones, hydrocarbons such as ligroin, cyclohexane and kerosene, methylformamide and the like can be used, but when used for an aqueous resin, water or water and a mixture of the above solvents can be used.

As a method for producing the transfer sheet, the recording ink produced by the above method may be applied to a suitable substrate.

Suitable substrates for applying ink include thin paper such as condenser paper and glassine paper, and plastic film having good heat resistance such as polyester, polyamide and polyimide. 2 to 50 to improve heat transfer efficiency from the recording head to the dye
A thickness of about μm is suitable.

Examples of the thermal transfer method include a method in which the sheet produced by the above method or the like is superposed on a recording medium and then heated and pressed from the back surface of the sheet with a thermal recording head. Dye is transferred onto the recording material.

Examples of the recording material include polyolefin resins such as polyethylene and polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, vinyl polymers such as polyvinyl alcohol, polyvinyl acetate and polyacrylic ester. Polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins,
Copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, cellulosic resins such as ionomers, cellulose diacetate and cellulose triacetate, fibers made of polycarbonate, polysulfone, polyimide, woven fabrics, films, sheets, molding Things etc. are mentioned. Particularly preferred is a woven fabric, sheet or film made of polyethylene terephthalate.

As the recording material, plain paper coated with, impregnated with, or laminated with a resin film is prepared by adding acidic fine particles such as silica gel to the resin used for preparing the ink. Alternatively, a special processed paper that has been acetylated can be used. In this case, excellent recording can be performed with excellent image stability under high temperature and high humidity. It is also possible to use films of various resins or synthetic papers made from them. Furthermore, after transfer recording, a polyester film, for example, is hot-pressed and laminated on the transfer recording surface, whereby the coloring of the dye can be improved and the storage stability of the recording can be achieved.

[0069]

EXAMPLES The present invention will be described in detail below with reference to examples.
In addition, "part" in an Example represents a weight part. "%" Represents% by weight.

Example 1 (1) Method for preparing ink Formula (3) below

[0071]

[Chemical 8] 4.5 parts of an orange compound represented by the following formula (4)

[0072]

[Chemical 9] 5.5 parts of a blue compound represented by the following formula (5)

[0073]

[Chemical 10] The mixture prepared by adding 2.0 parts of the red dye represented by 1 and 10.0 parts of polybutyral resin into 40.0 parts of methyl ethyl ketone and 40.0 parts of toluene is mixed with glass beads using a paint conditioner for about 30 minutes. The ink was prepared by processing.

(2) Method for producing transfer sheet Using a gravure proofing machine (plate depth: 30 μm), a 3.5 μm-thick polyethylene terephthalate film having a back surface heat-treated with the above ink has a dry weight of 1.0 g / m ² . And coated and dried.

(3) Method for producing recording material Polyester resin (Vylon 103 manufactured by Toyobo, Tg
= 47 ° C.) 0.8 part, EVA polymer plasticizer (Elvalloy 741p manufactured by Mitsui Polychemicals Tg = 37 ° C.) 0.2
Part, amino-modified silicone (KF-857, Shin-Etsu Chemical Co., Ltd.) 0.04 part, epoxy-modified silicone (KF-10
3 Shin-Etsu Chemical Co., Ltd.) 0.04 parts, methyl ethyl ketone /
Toluene / cyclohexane (weight ratio 4: 4: 2) 9.0
Parts and the above were mixed to prepare a coating liquid. A bar coater (manufactured by RK. Print Cort Insutruments No. 10) was applied to a synthetic paper (Yupo FPG # 150, manufactured by Oji Yuka).
Is applied at a rate of 4.5 g / m ² when dried, and 10
It was dried at 0 ° C. for 15 minutes.

(4) Transfer Recording The transfer sheet and the recording material are superposed with the ink application surface and the coating liquid application surface facing each other, and the applied voltage of 100 V to the thermal recording head is applied from the back surface of the thermal transfer sheet.
Recording is performed under the condition that the printing time is 4.0 milliseconds and the color density is 2.
A black record of 1 was obtained. The color density was measured using a density system RD-918 manufactured by Macbeth Co., USA. Further, a light resistance test was carried out at a black panel temperature of 63 ± 2 ° C. using a xenon fade meter (manufactured by Suga Test Machine Co., Ltd.) as a light resistance tester for the obtained recording. 40 records
Almost no discoloration occurred after irradiation for a long time, and the image stability under high temperature (50 ° C.) and high humidity (80%) was excellent.

In the storage stability test, the produced transfer sheet was left standing at 25 ° C. for 2 months and then transfer recording was carried out. When compared with the transfer recording density immediately after preparation of the transfer sheet, the same value as the color density of 2.1 was obtained. The results obtained were good.

The fastness of the recorded image obtained is 50 ° C.
After being left in the atmosphere for 48 hours, the sharpness of the image and the coloring when rubbing the surface with a white paper were judged, and the sharpness of the image did not change. Was good.

Examples 2 to 6 Using the dyes shown in Tables 12 and 13 in place of the dye used in Example 1, a transfer sheet and a recording material were prepared in the same manner as in Example 1 to perform transfer recording. When I went, Table 12
Black having the densities shown in Tables 13 and 13 were obtained, and the fastness thereof was excellent as in Example 1.

[0080]

[Table 12]

[0081]

[Table 13] Comparative Examples 1 to 2 By using the dyes shown in Table 14 in place of the dyes used in Example 1, a transfer sheet and a recording material were prepared in the same manner as in Example 1, and transfer recording was performed.

In Comparative Example 1, the solubility of the dyes (A) and (B) was low, and the sublimability was different from each other. Therefore, the obtained image was not black, but was dark red.

In Comparative Example 2, the solubility of the dye (D) was high, but the absorption at the wavelength of 400 to 550 nm was sharp, and the solubility of the dye (E) was low, and the obtained transferred image was red. The color density was low.

[0084]

[Table 14] Example 7 Using the blue dye represented by the following formula (6), an ink was prepared, a transfer sheet and a recording material were prepared by the following methods, and transfer recording was performed.

[0085]

[Chemical 11] (1) Method for preparing ink 3 parts of the dye of (6) above, 4.5 parts of polybutyral resin,
Methyl ethyl ketone 46.25 parts, toluene 46.25
Parts, using glass beads with a dye mixture of the above composition,
The ink was prepared by mixing with a paint conditioner for about 30 minutes.

(2) Method for producing transfer sheet Using a gravure proofing machine (plate depth 30 μm), a 9 μm-thick polyethylene terephthalate film having a back surface heat-treated with the above ink has a dry weight of 1.0 g / m ² . And then dried.

(3) Method for producing recording material Polyester resin (Vylon 103, Toyobo Co., Ltd. Tg
= 47 ° C.) 0.8 part, EVA polymer plasticizer (Elvalloy 741p manufactured by Mitsui Polychemical, Tg = 37 ° C.)
2 parts, amino modified silicone (KF-857 Shin-Etsu Chemical Co., Ltd.) 0.04 parts, epoxy modified silicone (KF-1)
03 Shin-Etsu Chemical Co., Ltd.) 0.04 parts, methyl ethyl ketone / toluene / cyclohexane (weight ratio 4: 4: 2) 9.
A coating liquid was prepared by mixing 0 parts and the above, and a bar coater (RK. Print) was added to synthetic paper (Yupo FPG # 150 manufactured by Oji Yuka).
Coat Insutruments Manufacturing No. 1) was used to apply at a rate of 4.5 g / m ² when dried, and dried at 100 ° C for 15 minutes. (4) Transfer recording The transfer sheet and the recording material are overlapped with the ink application surface and the coating liquid application surface facing each other, and the thermal recording head applied voltage of 10 V and the printing time of 4 from the back surface of the thermal transfer sheet. Recording was performed under the condition of 0.0 ms, and the color density was 2.6.
A blue record of 6 was obtained. The color density is densitometer RD-514 (filter: manufactured by Macbeth Co., USA).
Ratten No. 58).

The color density was calculated by the following formula.

Color Density = log ₁₀ (I ₀ / I) I ₀ = Intensity of Reflected Light from Standard White Reflector I = Intensity of Reflected Light from Test Object In addition, a light resistance test of the obtained record was conducted. 120 KJ using a xenon fade meter (manufactured by Suga Test Instruments Co., Ltd.)
The residual ratio of the color density when irradiated with the light of 92.1% was 92.1%, the color hardly changed, and the stability of the image under high temperature and high humidity was excellent. In addition, the fastness of the obtained recorded image is 50 ° C.
After being left in the atmosphere for 48 hours, it was judged by the sharpness of the image and the coloring when the surface was rubbed with a white paper. The sharpness of the image did not change, and the white paper was not colored. Was good.

Example 8 Using the compound of the following formula (7), an ink was prepared, a transfer sheet and a recording material were prepared and transfer recording was carried out.

[0091]

[Chemical 12] Ink was prepared, a transfer sheet and a recording material were prepared and transfer recording was carried out in the same manner as in Example 7, and blue recording having a color density of 2.81 was obtained. All of these records were subjected to a light resistance test in the same manner as in Example 7, and the residual ratio of color density was 9
It was 1.9%, and the stability of the image under high temperature and high humidity was also excellent. A fastness test was conducted in the same manner as in Example 7,
The sharpness of the image did not change, the white paper was not colored, and the fastness of the recorded image was good.

Examples 9 to 20 The azo dyes shown in Tables 15 and 16 were produced according to the same method as in Example 7, and similarly ink preparation, transfer sheet preparation, recording material preparation and transfer recording were carried out. Done, Table 15,
The respective recording densities shown in 16 were obtained.

All of these records were subjected to a light resistance test in the same manner as in Example 7. As a result, as shown in Tables 15 and 16, the records showed almost no change and the images under high temperature and high humidity were not changed. It was also excellent in stability. Further, a fastness test was conducted in the same manner as in Example 7, but the sharpness of the image did not change, the white paper was not colored, and the fastness of the recorded image was good.

[0094]

[Table 15]

[0095]

[Table 16] Comparative Example 3 In the same manner as in Example 7, using the compound of the following formula (8), ink was prepared, a transfer sheet and a recording material were prepared, and transfer recording was performed.

[0096]

[Chemical 13] The color density during transfer remained at 2.1 due to crystallization of the dye on the ribbon. When this recording was subjected to a light resistance test in the same manner as in Example 7, the color fading was severe and the color density residual ratio was 58.7%. Especially in the low-concentration test, the hue changed to reddish purple or disappeared. Also,
In the fastness test, some contamination was observed when rubbing the image surface with a blank sheet.

[0097]

EFFECTS OF THE INVENTION A compounded black system produced by adding one or more dyes represented by the general formula (1) of the present invention and one or more dyes represented by the general formula (2), and optionally a red dye. The sublimation transfer sheet has good solubility of the compounded dye in a solvent and a binder resin, and thus has good storage stability of the dye in the binder resin on the sheet.

Further, in the transfer sheet of the present invention, the sublimation speed of the ink due to the heating of the thermal recording head at the time of transfer is good, and the hue transferred to the image receiving paper is black close to carbon black and has a high color value. Further, since the sublimability of each dye is similar, it is possible to transfer without changing the color tone from gray to black. In addition, it is a black sublimation transfer sheet which has very good storage stability and is of practical value.

The azo dye represented by the general formula (2) can suppress the sublimation transfer amount of the dye by changing the energy applied to the thermal recording head at the time of thermal transfer. Therefore, gradation recording is easy, Suitable for full color recording. Further, since it is stable against heat, light, moisture, chemicals, etc., it is not thermally decomposed during transfer recording, and the obtained record is excellent in storability.

Further, since the above dye has good solubility in an organic solvent and dispersibility in water, it is easy to prepare a highly concentrated ink which is uniformly dissolved or dispersed, and as a result, the color density It is a dye that can obtain good recording and is practically valuable.

Claims (4)

[Claims] 1. General formula (1) Ar ₁ -N = N-Ar ₂ -N = N-Ar ₃ (1) [wherein Ar ₁ , Ar ₂ and Ar ₃ are each independently,
The aryl group which may have a substituent is shown. ] The orange dye represented by the formula and the general formula (2): [In the formula, R ₁ , R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, a nitro group, a hydroxy group, an alkyl group which may have a substituent, an alkoxy group, an alkylsulfonylamino group or an alkylcarbonyl group. It represents an amino group, and R ₄ and R ₅ each independently represent an alkyl group which may have a substituent. ] A black dye for thermal transfer recording comprising one or more blue dyes each represented by 2. A blue dye is represented by R ₁ in the general formula (2).
Represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a nitro group, and R ₂ and R ₃ each independently or independently represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylcarbonylamino group or an alkylsulfonylamino group, The black dye for thermal transfer recording according to claim 1, wherein R ₄ represents an alkyl group which may have a substituent, an aralkyl group or an alkylcarboxyethyl group, and R ₅ represents an alkoxycarbonylethyl group. . 3. A heat-sensitive transfer sheet containing the black dye according to claim 1. 4. In the general formula (2), R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a nitro group, and R ₂ and R ₃ are the same or independently of each other, a hydrogen atom, an alkyl group or an alkoxy group. Group, an alkylcarbonylamino group or an alkylsulfonylamino group, R ₄ represents an optionally substituted alkyl group, an aralkyl group or an alkylcarboxyethyl group, R 4
₅ is a blue dye for sublimation thermal transfer recording represented by an alkoxycarbonylethyl group.