JPH106657A - Thermosensitive transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high density of black and also a record in close to achromatic color and enable the recording in black almost free from chromatic variations due to color density by forming a coloring material layer containing plural different colors of at least, disazo color and monoazo color on a thin leaflike base material. SOLUTION: A coloring material layer containing plural colors of at least, disazo color and monoazo color is formed on a thin leaflike base material to obtain a thermosensitive transfer sheet. The disazo color is an orange color expressed by formula I (X<1> -X<4> are an H atom, a methyl group and a nitro group; and Y<1> -Y<6> are an H atom, an ethyl group and an ethoxy group). The monoazo color is a blue color expressed by formula II (Z<1> is a cyano group, a nitro group; Z<2> is an H atom, a cyano group; X<5> is a methyl group: Y<7> is a methoxy group; R<1> , R<2> are H atom, a lower alkyl group, an alkenyl group and an aryl group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet used for a color hard copy by a so-called thermal transfer recording system. In particular, the present invention relates to a heat-sensitive transfer sheet used in a sublimation transfer recording system.

[0002]

2. Description of the Related Art In recent years, techniques for converting a color image based on an electric signal such as a video image into a color hard copy have been advanced, and for example, methods such as electrophotography, ink jet, and thermal transfer have been studied. Of these,
In particular, the thermal transfer method is advantageous because the maintenance and operation of the apparatus are easy and the apparatus can be downsized.

[0003] The thermal transfer method involves melting a color material layer on a base material by heating and transferring the same to a recording material, and a so-called transfer method in which only the dye in the color material layer is transferred to the recording material. A sublimation transfer method is known. The sublimation transfer method is capable of controlling the amount of the dye to be transferred by the degree of heating, so that expression with density gradation is possible, and is suitable for obtaining a fine image such as a full-color print.

A normal color print is expressed with three colors of yellow, magenta and cyan, and a heat-sensitive transfer sheet used in a sublimation transfer system also has a color material layer of three colors of yellow, magenta and cyan on a substrate. There are many which have in a field sequence. On the other hand, in order to better express black, a thermal transfer sheet having four color material layers with a color material layer dedicated to black or a monochrome image such as an X-ray is reproduced and reproduced. There is also a demand for a black-only transfer sheet having only a black color material layer. Dyes in these colorant layers for black include, for example, usually dyes of each hue of yellow, magenta, and cyan as described in JP-A-61-148096 and JP-A-3-7387. Mixed.

[0005]

In order to be a good black transfer sheet, it is necessary to be able to express dark black, to be close to achromatic, that the color quality does not change with density, to have weather resistance such as light fastness, and to preserve. Although excellent properties are required, it is extremely difficult to satisfy all of them. In order to express deep black, it is necessary to use a combination of dyes having a high transfer density. In combination with low transfer sensitivity, high density black cannot be expected from the beginning, but when one of the compounded dyes has low transfer sensitivity and cannot produce high dark color, the color quality of other compound dyes at high density Cannot be obtained because of the strong appearance of black.

In order to be able to express black, a pigment
Color material layer as a result of transfer
The color tone when transferred is close to an achromatic color that is not biased to a specific color.
It is necessary to make it. In order to approach achromatic color,
A in CIELAB color system^*Value, b^*When the value is measured
a^*= 0, b^*ΔEc value (a^*× a^*+ B ^*
× b^*Square root of the
New selection combinations are required and can be easily achieved
Absent.

Further, in order to be achromatic, it is necessary for light to be absorbed evenly in the entire wavelength range of light perceived by human eyes. On the other hand, a vivid color means that light absorption is sharp. Therefore, in the case of a mixture of clear colors, it is difficult to show uniform absorption in the absorption wavelength range of all the light perceived by the human eye, and there are some places where the absorption is small. Therefore, in order to obtain good black, it is preferable to combine dyes that are not as clear as possible to avoid a portion having little absorption. For this reason, many dyes for sublimation transfer have been developed using disperse dyes for dyeing fibers as models, but also in the case of disperse dyes, black dyes are mainly combined with orange and blue dyes. There are many.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, in a thermal transfer sheet used in a thermal transfer recording system, a disazo dye and a monoazo It has been found that by containing a system dye, a high black density is achieved, a recording close to an achromatic color is obtained, and a black recording with little change in color quality due to the density is made possible, and the present invention has been achieved.

That is, the gist of the present invention is a thermal transfer recording system in which a thermal transfer sheet in which a color material layer is provided on a thin sheet-like base material is heated to transfer a dye in the color material layer to a recording medium to perform recording. Wherein the colorant layer contains a plurality of pigments having different hues, and the pigment contained in the colorant layer is at least a disazo pigment and a monoazo pigment. It exists in the heat-sensitive transfer sheet. In the present invention, a dye represented by the following general formula (1) is used as a disazo dye, and a dye represented by the following general formula (2) is used as a monoazo dye.

[0010]

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[0011]

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The disazo dye represented by the general formula (1) is an orange dye, and the monoazo dye represented by the general formula (2) is a blue dye. As the substituent of the general formula (1), X ¹ , X ² , X ³ and X
⁴ is a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxyl group, a nitro group, a cyano group, an acetylamino group, a methoxycarbonyl group, an ethoxycarbonyl group, a methoxycarbonylamino group, an ethoxycarbonylamino group, Methylsulfonyl group, ethylsulfonyl group, dimethylsulfamoyl group, fluorine atom, chlorine atom,
Or a bromine atom, Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵
And Y ⁶ represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a fluorine atom, a chlorine atom, a bromine atom or a hydroxyl group, and Y ¹ and Y ² , or Y ⁴ and Y ⁵ are connected to each other to form an aromatic compound. It may form a ring.

More preferably, X ¹ , X ² and X
³ represents a hydrogen atom, a methyl group, a methoxy group, a nitro group, an acetylamino group, a methoxycarbonylamino group, or a chlorine atom, and Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ and Y
⁶ represents a hydrogen atom, a methyl group, a methoxy group, a chlorine atom or a hydroxyl group, and Y ¹ and Y ² , or Y ⁴ and Y ⁵ may be linked to each other to form an aromatic ring.

The lower in the substituent of the general formula (2) is
Means 1 to 8 carbon atoms. Further, as the substituent in the general formula (2), preferably, Z ¹ represents a cyano group or a nitro group, Z ² represents a hydrogen atom, a chlorine atom, a bromine atom, a cyano group or a methylsulfonyl group, and X ⁵ represents a hydrogen atom. atom,
A chlorine atom, a methyl group, a methoxy group or an acylamino group; Y ⁷ represents a hydrogen atom, a methyl group, a methoxy group, an ethoxy group or a methoxyalkoxy group, and R ¹ , R ²
Represents a hydrogen atom, lower alkyl group, alkenyl group, aralkyl group, aryl group, halogeno lower alkyl group, hydroxy lower alkyl group, cyano lower alkyl group, lower alkoxy lower alkyl group, lower alkenyloxy lower alkyl group, lower aralkyloxy lower alkyl group. Group, aryloxy lower alkyl group, tetrahydrofurfuryloxy lower alkyl group, lower alkoxycarbonyl lower alkyl group, arylcarbonyloxy lower alkyl group, lower alkylcarbonyloxy lower alkyl group, lower alkoxycarbonyloxy lower alkyl group, lower alkoxyethoxy lower Represents an alkyl group.

More preferably, Z ¹ represents a cyano group or a nitro group, Z ² represents a chlorine atom, a bromine atom or a cyano group, X ⁵ represents an acylamino group, Y ⁷ represents a hydrogen atom, a methoxy group or an ethoxy group. R ¹ , R ²
Is a hydrogen atom, a lower alkyl group, a lower alkenyl group, an aralkyl group, a monochloro lower alkyl group, a hydroxy lower alkyl group, a cyanoethyl group, a lower alkoxyalkyl group, a lower alkenyloxyethyl group, a lower aralkyloxyethyl group, an aryloxy lower alkyl group , A tetrahydroxyfurfuryloxyethyl group or a lower alkoxyethoxyethyl group.

The disazo dye represented by the general formula (1) of the present invention is already known from Japanese Patent Application Laid-Open No. Sho 60-180889, and when mixed with a blue dye having a uniform sublimation rate in the text, it becomes black. There is a description that is suitable for obtaining. JP-A-5-201147 also discloses a part of the dye represented by the general formula (1). On the other hand, some of the monoazo dyes represented by the general formula (2) are known from JP-A-62-132684 to be used for thermal transfer.

The black thermal transfer sheet of the present invention is selected from an extremely large number of possible combinations of dyes, and comprises a disazo dye represented by the above formula (1) and a general formula (2). Is obtained by providing a coloring material layer containing a monoazo dye represented by the following formula on a thin-leaf substrate.

It is necessary to consider the transfer sensitivities of the individual dyes in order to mix the dyes so that the hue of the resulting black recording is stable. Therefore, the compounding ratio of each dye is, in 100% by weight of all dyes in the color material layer,
Usually, the disazo dye represented by the general formula (1) is 20 to 5
It is suitable that the monoazo dye represented by the general formula (2) is contained at a ratio of 10 to 70% by weight. Preferably, the disazo dye is 30 to 45% by weight, and the monoazo dye is 20 to 45% by weight.
It is desirable to mix at 65% by weight.

In blending these pigments, two or more pigments of the general formulas (1) and (2) may be blended and used as necessary. Further, in addition to the dyes represented by the general formulas (1) and (2), for the purpose of adjusting the color tone within a range that does not impair the properties, for example, an indoaniline-based dye represented by the following general formula (3), A dicyano imidazole azo dye represented by the formula (4) may be added.

[0020]

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(Wherein X ⁶ is a hydrogen atom, a halogen atom,
Lower alkyl group, a lower alkoxy group, formylamino group, lower acylamino group, a lower alkylsulfonyl amino group or a lower alkoxycarbonylamino group, -A- represents -CO- or -COO-, R ³ is a hydrogen atom, A halogen atom, an alkyl group, R ⁴ is a hydrogen atom, a halogen atom, an optionally substituted alkyl group,
R ⁵ , R ⁶ and R ^{7 each} represent an optionally substituted lower alkyl group, an optionally substituted lower alkenyl group, an optionally substituted lower aryl group, an optionally substituted aralkyl group or a substituted Represents an optionally substituted heterocyclic ring.

Preferably, X⁶Is a hydrogen atom, a chlorine atom,
Represents a methyl group, a methoxy group, an ethoxy group, -A-
-CO- or -COO-, and R^ThreeIs a hydrogen atom or
Represents a chlorine atom;^FourIs hydrogen atom, chlorine atom, methyl
A group or an ethyl group; ^FiveIs lower alkyl group, lower
Alkenyl, aralkyl, aryl, halogeno low
Lower alkyl group, hydroxy lower alkyl group, cyano lower
Alkyl group, tetrahydrofurfuryl group, lower alkoxy
Lower alkyl group, aralkyloxy lower alkyl group,
Aryloxy lower alkyl group, alkenyloxy lower
Alkyl group, lower alkoxyethoxy lower alkyl group,
Or a tetrahydrofurfuryloxy lower alkyl group,
Represents a heterocyclic ring, R^Five, R⁶Is lower alkyl group, aralkyl
Group, halogeno lower alkyl group, hydroxy lower alkyl
Group, tetrahydrofurfuryl group, lower alkoxy lower
Alkyl group, aralkyloxy lower alkyl group, aryl
Ruoxy lower alkyl group, lower acyloxy lower alkyl
Group, arylcarbonyloxy lower alkyl group, lower
Alkoxycarbonyloxy lower alkyl group, or lower
Represents a lower alkoxyethoxy lower alkyl group. )

[0023]

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(Wherein X ⁷ is a hydrogen atom, a halogen atom,
Lower alkyl group, a lower alkoxy group, formylamino group, lower acylamino group, a lower alkylsulfonyl amino group or a lower alkoxycarbonylamino group, Y ⁸ represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, R ^8, R ⁹ and R ¹⁰ are a lower alkyl group which may be substituted, a lower alkenyl group which may be substituted, a lower aryl group which may be substituted, an aralkyl group which may be substituted or Represents a good heterocycle.

Preferably, X ⁷ is a hydrogen atom, a methyl group,
It represents an ethyl group, a methoxy group, an ethoxy group, formylamino group, lower acylamino group, a lower alkylsulfonyl amino or ethoxycarbonylamino group, Y ⁸
Represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, and R ⁸ , R ⁹ and R ¹⁰ are a lower alkyl group which may be substituted, a lower alkenyl group which may be substituted, It represents a good lower aryl group or an aralkyl group which may be substituted. )

Such an indoaniline dye is disclosed in
JP-A-31292 and JP-A-61-35994, and dicyanoimidazole azo dyes are described in JP-A-61-227091.
It is necessary that the amount of the dye added does not exceed 50% by weight of the indoaniline dye and does not exceed 20% by weight of the dicyanoimidazole azo dye based on all the dyes in the colorant layer. Also, based on 100% by weight of the binder resin in the color material layer, the indoaniline dye does not exceed 100% by weight,
The dicyanoimidazole azo dye should not exceed 40% by weight.

Using a dye compounded in such a mixing ratio,
Black obtained using the thermal transfer sheet made from
Achromatic color that is not biased toward the color of CIELAB color system
And a ^*Value, b^*A when the value is measured^*= 0, b^*= 0
ΔEc value from ((a^*× a ^*+ B^*× b^*) Square
Root) is 10 or less, preferably 6 or less.

Examples of the thin sheet-like substrate used in the thermal transfer sheet of the present invention include polyethylene terephthalate film, polyamide film, polyaramid film, polyimide film, polycarbonate film, polyphenylene sulfide film, polysulfone film,
Cellophane, triacetate film, polypropylene film and the like can be mentioned. Among them, polyethylene terephthalate film is preferable in terms of mechanical strength, dimensional stability, heat resistance, price and the like, and biaxially stretched polyethylene terephthalate film is particularly preferable. The thickness of these thin leaf-shaped substrates is usually 1 to 30 μm, preferably 2 to 10 μm.
μm.

In order to improve the adhesion to the color material layer, the surface of the base film may be subjected to a corona treatment or a polyester-based resin, a cellulose-based resin, a polyvinyl alcohol-based resin, a urethane-based thin leaf-shaped substrate. An anchor coat made of a resin, a polyvinylidene chloride resin, or the like may be provided. The color material layer can be formed on the thin leaf-shaped substrate by a usual method. For example, an ink may be prepared by dissolving or dispersing a pigment and a binder resin having good heat resistance in an appropriate solvent, and then applying the ink to a base film and drying.

Generally, the higher the ratio of the dye in the binder resin, the higher the transfer sensitivity and the highest attainable density, and the lower the ratio of the dye, the lower the sensitivity and the attainable density. However, when the ratio of the dye becomes extremely high, the dye precipitates out of the binder under high temperature, high humidity, or long-term storage, which adversely affects a transferred image. Therefore, in consideration of the storage stability and transferability of the heat-sensitive transfer sheet, the mixing ratio of the binder and the dye is suitably in the range of 1: 2 to 2: 1, and more preferably 1: 1.5 to 1: 1. 0.5: 1.

As the binder resin in the color material layer, polycarbonate resin, polysulfone resin, polyvinyl butyral resin, phenoxy resin, polyarylate resin, polyamide resin, polyaramid resin, polyimide resin, polyetherimide resin, polyester resin, acrylonitrile-styrene Examples include resins and cellulosic resins such as acetylcellulose, methylcellulose, ethylcellulose and the like. Solvents used include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; alcohols such as isopropanol, butanol and methyl cellosolve. System solvents; ether solvents such as dioxane and tetrahydrofuran; and amide solvents such as dimethylformamide and N-methylpyrrolidone.

In the ink for forming the color material layer, in addition to the above components, if necessary, organic or inorganic non-sublimable particles, a dispersant, an antistatic agent, an antiblocking agent, a defoaming agent Additives such as agents, antioxidants and viscosity modifiers can be added. Further, an infrared absorbing agent or carbon black can be added for use in a sublimation transfer system using laser light.

The method of applying these inks is not particularly limited. For example, a gravure coater, a reverse roll coater, or the like can be used. For example, "Printing ink handbook" (edited and published by the Printing Ink Industry Federation, 197)
8 years) can be referred to. The coating film thickness is suitably from 0.1 to 5 μm, more preferably from 0.5 to 2 μm as a dry film thickness.

Further, in the present invention, a heat-resistant layer may be provided on the surface of the thermal transfer sheet opposite to the color material layer, if necessary. Although there is no particular limitation on the heat-resistant layer, for example, those using a cured resin such as an ultraviolet-curable resin and those using a thermoplastic resin having a high Tg are known. Since the heat-resistant layer needs to have heat-sliding properties with respect to the thermal head in addition to the heat resistance of the thermal head, a lubricant such as silicone oil is generally added.

[0035]

The present invention will be described below in detail with reference to examples.
However, this example does not limit the present invention at all.
Unless otherwise specified,% and parts are by weight.
You. (Example 1) (a) Preparation of thermal transfer sheet Dye 1-1 (in the general formula (1), X¹, X^Two, X^Three,
X^Four, Y^Three, Y^Four, Y ^FiveAnd Y⁶Is a hydrogen atom, Y¹And Y
^TwoAre linked to form a 6-membered aromatic ring,
Has no substituents other than elementary atoms. ) 37 parts, dye 2-1
(In the general formula (2), X^FiveIs ethylcarbonylamino
Group, Y⁷Is a hydrogen atom, Z¹Is a cyano group, Z^TwoIs a bromine field
Child, R¹And R^TwoIs ethyl group) 63 parts and phenoxy resin
(Product name PKHJ, manufactured by UCC Corporation) 100 parts and Mechi
Mix and stir 200 parts of ethyl ketone and 500 parts of toluene
6 μm polyester film
Using a bar coater so that the dry film thickness becomes 2 μm.
Coated and dried. Acrylic resin (brand name BR-
80, manufactured by Mitsubishi Rayon Co., Ltd.) 10 parts by weight, amino-modified
Silicone oil (trade name KF393, Shin-Etsu Chemical Co., Ltd.)
1 part by weight) and 89 parts by weight of toluene were mixed and dissolved.
Using a bar coater, dry the solution to a thickness of 1 μm.
Coating and drying were performed to provide a heat-resistant layer.

(B) Preparation of Image Receptor 70 parts of polyvinyl phenyl acetal resin, 30 parts of vinyl chloride / vinyl acetate / vinyl alcohol copolymer resin (trade name: SREC A, manufactured by Sekisui Chemical Co., Ltd.), silicone varnish (trade name: TSR- 160, solid content concentration 60%, manufactured by Toshiba Silicone Co., Ltd.) 30 parts, hexamethylene diisocyanate polyfunctional isocyanate compound (trade name: Mitec NY-710A, solid content concentration 75%, manufactured by Mitsubishi Chemical Corporation) 15 parts, amino 2.5 parts of modified silicone oil (trade name KF393, manufactured by Shin-Etsu Chemical Co., Ltd.)
A liquid composed of 600 parts of methyl ethyl ketone and 600 parts of toluene was applied to a synthetic paper (trade name: Yupo FPG150, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) with a wire bar, dried (dry film thickness: about 5 μm), and further dried in an oven. An image receiver was prepared by heat treatment at 12 ° C. for 12 hours. The polyvinyl phenyl acetal resin is obtained by acetalizing polyvinyl alcohol (having a degree of saponification of 99 mol% and a degree of polymerization of 1700) with phenylacetaldehyde, and is represented by the following structural formula (5).

[0037]

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(C) Print Record The color material layer surface of the heat-sensitive transfer sheet prepared as in (a) above and the resin-coated surface of the image receiving member prepared as in (b) above are overlapped. Using a partial grace type line thermal head having a heating resistor density of 6 dots / mm, 16 lines (dots) / mm in the feed direction for 16 ms
Printing was performed at an applied power of 0.20 W / dot at a speed of / line. The time applied to the head per line was set to 13 ms and 8 ms, respectively, to obtain dark color and light color prints, respectively.

(D) Measurement of density and chromaticity A reflection densitometer for dark colors of printed matter printed as in (c) above (trade name: Macbeth RD-927, manufactured by Macbeth)
The filter was measured with an orthomatch. As a result, a concentration of 1.71 was obtained. Furthermore, the CIELAB chromaticity of each of the light color and the dark color is determined according to JIS Z-872.
Using a color difference meter (trade name: spectral color difference meter SZ- # 80, manufactured by Nippon Denshoku Industries Co., Ltd.)
The measurement was performed with a C light source and a viewing angle of 2 degrees. As a result, in dark colors,
a ^* = 3.6, b ^* =-1.9, and a ^* =-
3.4, b ^* =-1.1, and the ΔEc values from a ^* = 0, b ^* = 0 were 4.1, 3.6, respectively, which were close to an achromatic color.

(Examples 2 to 7) A test was carried out in the same manner as in Example 1 except that the composition of the dye shown in Table 1 was used instead of the composition of the dye used in Example 1, and the results were shown in Table 1. 3 is shown. In each case, high density and near-medium black were obtained.

[0041]

[Table 1]

The dye 3-1 is represented by the formula (3):
⁶ is a methyl group, -A- is -CO-, R ³ is a hydrogen atom, R
⁴ and R ⁵ are methyl groups, and R ⁶ and R ⁷ are ethyl groups. The dye 3-2 is represented by the formula (3), wherein X ⁶ is a methyl group,
-A- is -COO-, R ³ is a chlorine atom, R ⁴ is a methyl group, R ^5, R ⁶ and R ⁷ is an ethyl group. Dye 4-1
In the general formula (4), X ⁷ is an acetylamino group,
Y ⁸ is a hydrogen atom, R ⁸ is an allyl group, and R ⁹ and R ¹⁰ are normal propyl groups.

(Comparative Examples 1 to 3) Tests were conducted in the same manner as in Example 1 except that the dyes used in Example 1 were replaced with the compounds shown in Table 2 below. 3 is shown. In Comparative Examples 1 and 2, moderate black was obtained, but the sensitivity was insufficient. In Comparative Example 3, a ^* = 0 and b ^* = 0 when the sensitivity was low and the concentration was different.
Was large. The dye 6 is a yellow dye, the dye 7 is a red dye, and the dye 8 is a blue dye.

[0044]

[Table 2]

Dye 6 is represented by the following structural formula (6). Dye 7 was represented by the following structural formula (7). In the dye 3-3, in the general formula (3), X ⁶ is a hydrogen atom, and -A- is -COO.
-, R ³ is a chlorine atom, R ⁴ is a methyl group, R ⁵ is a propyl group, and R ⁶ and R ⁷ are ethyl groups. Dye 8 was represented by the following structural formula (8).

[0046]

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[0047]

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[0048]

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[0049]

[Table 3] However, ΔEc value is a value from a ^* = 0, b ^* = 0

[0050]

According to the heat-sensitive transfer sheet of the present invention, a medium black having a high transfer density can be obtained.

Claims (5)

[Claims] 1. A heat-sensitive transfer recording method used in a heat-sensitive transfer recording system in which a heat-sensitive transfer sheet provided with a color material layer on a thin-leaf base material is heated to transfer a dye in the color material layer to a recording medium to obtain recording. In the sheet, the coloring material layer contains a plurality of dyes having different hues,
A heat-sensitive transfer sheet, wherein the coloring material contained in the coloring material layer comprises at least a disazo coloring matter and a monoazo coloring matter. 2. The heat-sensitive transfer sheet according to claim 1, wherein the disazo dye is a dye represented by the following general formula (1), and the monoazo dye is a dye represented by the following general formula (2). A heat-sensitive transfer sheet, characterized in that: Embedded image (Wherein X ¹ , X ² , X ³ and X ⁴ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, a nitro group,
Represents a cyano group, an acyl group, an acylamino group, an alkoxycarbonyl group, an alkylsulfonyl group, a sulfamoyl group which may be substituted by alkyl, or a halogen atom, and represents Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ and Y ⁶ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a hydroxyl group, and Y ¹ and Y ² , or Y ⁴ and Y ⁵ may be linked to each other to form an aromatic ring. ) (In the formula, Z ¹ represents a cyano group or a nitro group, Z ² represents a hydrogen atom, a halogen atom, an acyl group, a cyano group or an alkylsulfonyl group, and X ⁵ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkyl group. An alkoxy group, a formylamino group, a lower acylamino group, a lower alkylsulfonylamino group or a lower alkoxycarbonylamino group, Y ⁷ represents a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group, and R ¹ and R ² represent Each independently represents a hydrogen atom, an optionally substituted lower alkyl group, an optionally substituted lower alkenyl group, an optionally substituted lower aryl group, an optionally substituted aralkyl group, Y ⁷ And R ¹ may combine with each other to form a 6-membered ring.) 3. The thermal transfer sheet according to claim 1, wherein the monoazo dye is contained in a ratio of 10 to 70% by weight based on all the dyes contained in the colorant layer. Sheet. 4. The thermal transfer sheet according to claim 1, wherein the disazo dye has a ratio of 20 to 50% by weight based on all dyes contained in the color material layer. Thermal transfer sheet. 5. The heat-sensitive transfer sheet according to claim 1, wherein the colorant layer contains a binder resin and a dye as main components, and the ratio of the dye is 50 to 200 parts by weight based on 100 parts by weight of the binder. A heat-sensitive transfer sheet characterized by the following range.