JPH0781251A - Heat transfer sheet - Google Patents

Abstract

PURPOSE:To obtain high black density by a method wherein a black dye layer contains at least respective one of yellow dyes, of magenta dyes and of cyan dyes represented by specified formulae. CONSTITUTION:In a heat transfer sheet concerned equipped with a black dye layer on one side of a base material sheet, the black dye layer is prepared by containing at least one of yellow dyes represented by the formula I, magenta dyes represented by the formula II and at least one selected from the group consisting of cyan dyes represented by the formula III, in which R1, R2, R4, R9, R10 and R12 represent substituted-or non-substituted-alkyl group, aryl group, allyl group, aralkyl group, R3 and R11 represent hydrogen atom, halogen atom, substituted-or non-substituted-alkyl group, acyl amino group, sulfonyl amino group or the like and R5 represents hydrogen atom, halogen atom, substituted-or non-substituted-aryl alkoxycarbonyl group, alkoxycarbonyl group, alkoxy group and alkyl 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 having a black dye layer, and in particular, while reducing stain resistance,
The present invention also relates to a thermal transfer sheet having a black dye layer which has good recording sensitivity and high black density.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer sheet having a dye layer provided on one surface of a base material sheet has been used when the output printing of a computer or a word processor, or various image formation is performed by a sublimation transfer method. This thermal transfer sheet is provided with a heat-resistant base sheet and a dye layer formed by applying and drying an ink in which a sublimable dye is mixed with a binder on the base sheet. Then, heat is applied from the back side of the thermal transfer sheet by a thermal head to transfer a large number of color dots of three colors or four colors to a transfer material to form a full-color image. The formed image is clear and excellent in transparency because the coloring material used is a dye, and has high reproducibility and gradation of intermediate colors, and it is possible to form high-quality images equivalent to conventional full-color photographic images. .

[0003]

By the way, in a thermal transfer sheet having a black dye layer on one surface of a substrate sheet, it is desired that the recording sensitivity is good and the black density after transfer is high. . Therefore, conventionally, it has been attempted to incorporate as much dye as possible into the black dye layer and increase the content rate to deal with it. However, there is a limit to the solubility of the dye, and an excessive addition beyond the limit causes a problem that it leads to staining. Further, in order to improve the solubility, DMF (N, N-dimethylformamide)
There has also been a problem in that high polar solvents such as above have to be used in a relatively large amount.

The present invention was devised in view of the above circumstances, and its object is, in particular, a black dye layer which has a good recording sensitivity and a high black density while having a low contamination property. The present invention is to provide a thermal transfer sheet including.

[0005]

In order to achieve such an object, the thermal transfer sheet of the present invention is a thermal transfer sheet having a black dye layer on a substrate sheet, wherein the black dye layer is At least one of the yellow dyes represented by the formulas [1] and [2], the magenta dye represented by the formula [3] below, the formula [4], the formula [5], the formula [6] and the formula [6] below. 7] and at least one cyan dye selected from the above.

[0006]

[Chemical 8] (In the formula [1], R ₁ and R ₂ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₃ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.)

[0007]

[Chemical 9] (In the formula [2], R ₄ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, and R ₅ is Represents a hydrogen atom, a halogen atom, a substituted or unsubstituted arylalkoxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted alkyl group.)

[0008]

[Chemical 10] (In the formula [3], R ₆ and R ₇ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₈ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.)

[0009]

[Chemical 11] (In the formula [4], R ₉ , R ₁₀ and R ₁₂ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group or an aralkyl group, and R ₁₁ Represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.)

[0010]

[Chemical 12] (In the formula [5], R ₁₃ and R ₁₄ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₁₅ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.)

[0011]

[Chemical 13] (In the formula [1], R ₁₆ , R ₁₇ and R ₁₉ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. the stands, R ₁₈ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group. )

[0012]

[Chemical 14] (In the formula [1], R ₂₀ and R ₂₁ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. )

[0013]

The dye layer of the thermal transfer sheet of the present invention, especially the black dye layer, contains the black dye obtained by mixing the predetermined yellow, cyan and magenta dyes, so that the stain resistance is reduced. However, the recording sensitivity is good and the black density after transfer can be high.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of the thermal transfer sheet of the present invention. In FIG. 1, the thermal transfer sheet 1 is a base sheet 1
1 and the dye sheet 12 of each color on one surface of the base sheet 11 are thermal transfer sheets. Then, the transfer dye layer 12
Is usually a yellow dye layer 12Y and a magenta dye layer 12
M, a cyan dye layer 12C, and a black dye layer 12B are repeatedly arranged.

Further, the individual dye layer 12C and the dye layer 12
The widths of M, the dye layer 12Y, and the dye layer 12B may be the widths actually required for one image formation, or may be integer multiples thereof, and are appropriately determined based on the size of the screen to be formed. be able to.

As the base sheet 11, the base sheet used in the conventional thermal transfer sheet can be used as it is and is not particularly limited. For example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
Polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber,
Plastic film such as ionomer, glassine paper,
Paper such as condenser paper and paraffin paper, non-woven fabric and the like are preferably used. Moreover, these composites can also be used as a base material sheet.

The thickness of such a base sheet can be appropriately determined so as to obtain the required strength and thermal conductivity, and is, for example, about 3 to 100 μm.

On such a base sheet, the black dye layer 12B is formed as one of the dye layers 12 as described above. The black dye layer 12B is a layer in which a binder carries a black hue dye formed by mixing a yellow dye, a magenta dye, and a cyan dye, which will be described later.

First, as the yellow dye contained in the black dye layer 12B of the present invention, at least one of the yellow dyes represented by the following formulas [1] and [2] is used.

[0021]

[Chemical 15]

[0022]

[Chemical 16] In the above formula [1], R ₁ and R ₂ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituent of R ₁ and R ₂ include ethyl group, 4-cyclohexylphenoxyethyl group, n-butyl group, phenyl group, 2-propenyl group and benzyl group. ₁ = ethyl group, R ₂
= 4-cyclohexylphenoxyethyl group is particularly preferred.

In the above formula [1], R ₃ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.

Specific examples of the substituent of R ₃ include a chlorine atom, a methyl group, an ethyl group, an acetylamino group, an ethylsulfonylamino group, an ethoxy group and the like.
—CH ₃ (a methyl group at the atom position number 3) is particularly preferred. In addition, the number of the substituents of R ₃ can be in the range of 1 to 4, which is a substitutable number in principle.

In the above formula [2], R ₄ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. .

Specific examples of the substituent of R ₄ include an ethyl group, an n-butyl group, a phenyl group, a 2-propenyl group and a benzyl group, among which n-C ₄ H ₉ (n-butyl group). Is particularly preferable.

In the above formula [2], R ₅ is a hydrogen atom, a halogen atom, a substituted or unsubstituted arylalkoxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkoxy group, or It represents a substituted or unsubstituted alkyl group.

Specific examples of the substituent of R ₅ include a chlorine atom, a phenylmethoxycarbonyl group, an ethoxycarbonyl group, a methoxy group, an ethyl group and the like. Among them, a phenylmethoxycarbonyl group attached to the atom position number 4 is particularly preferable. preferable. The number of substituents of R ₅ can be in the range of 1 to 5, which is a substitutable number in principle.

Such a yellow dye is contained in the dye composition of the black dye layer in an amount of 10 to 30% by weight, preferably 10 to 30% by weight.
20 wt% is contained. If the content ratio is out of the above range, the composition will not be extremely deteriorated in storage stability even if the composition is changed to some extent, but rather, it is not black.

Next, as the magenta dye contained in the black dye layer 12B of the present invention, the dye represented by the following formula [3] is used.

[0032]

[Chemical 17] In the above formula [3], R ₆ and R ₇ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituents of R ₆ and R ₇ include a benzyl group, a 2-propenyl group, an ethyl group, an n-butyl group, a 2-ethylbutyl group, a phenyl group and a 3-methylphenyl group. , Among them, R ₆ = benzyl group,
R ₇ = 2-propenyl group is particularly preferred.

In the above formula [3], R ₈ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted Represents an alkoxy group.

Specific examples of the substituent of R ₈ include chlorine atom, methyl group, acetylamino group, ethylsulfonylamino group, ethoxy group and the like. Among them, R ₈ = 3
-NHCOCH ₃ (acetylamino group position number 3 of the atoms) are particularly preferred. The number of substituents of R ₈ can be in the range of 1 to 4, which is a substitutable number in principle.

Such magenta dye is contained in the dye composition of the black dye layer in an amount of 20 to 40% by weight, more preferably 25 to 40% by weight.
35 wt% is contained. If the content ratio is out of the above range, the storage stability will not be extremely lowered by a slight compositional change as in the case of the yellow dye, but rather the black color will not be obtained.

Next, as the cyan dye contained in the black dye layer 12B of the present invention, at least one selected from the following formula [4], formula [5], formula [6] and formula [7] Cyan dye is used.

[0038]

[Chemical 18]

[0039]

[Chemical 19]

[0040]

[Chemical 20]

[0041]

[Chemical 21] In the above formula [4], R ₉ , R ₁₀ and R ₁₂ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. Represents

Specific examples of the substituents of R ₉ , R ₁₀ and R ₁₂ include a methyl group, an ethyl group, an n-butyl group, a phenyl group, a 2-propenyl group and a benzyl group. ₉ , R ₁₀ = -C ₂ H ₅ (ethyl group), R ₁₂ =-
CH ₃ (methyl group) is particularly preferable.

In the above formula [4], R ₁₁ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted Represents an alkoxy group.

Specific examples of R ₁₁ include chlorine atom, methyl group, ethyl group, acetylamino group, ethylsulfonylamino group, ethoxy group and the like, among which 3-CH ₃
(Methyl group of atom position number 3) is particularly preferable. The number of substituents of R ₁₁ can be in the range of 1 to 4, which is a substitutable number in principle.

In the above formula [5], R ₁₃ and R ₁₄ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. Represents

Specific examples of the substituent of R ₁₃ and R ₁₄ include n-butyl group, n-hexyl group, phenyl group and 2-
Examples thereof include a propenyl group and a benzyl group.
_{R 13, R 14 = n-} C 6 H 13 (n- hexyl group) is particularly preferred.

In the above formula [5], R ₁₅ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted Represents an alkoxy group.

Specific examples of the substituent of R ₁₅ include chlorine atom, methyl group, ethyl group, acetylamino group, ethylsulfonylamino group, ethoxy group and the like.
3-CH ₃ (a methyl group at the atom position number 3) is particularly preferred. In addition, the number of substituents of R ₁₅ can be in the range of 1 to 4, which is a substitutable number in principle.

In the above formula [6], R ₁₆ , R ₁₇ and R
₁₉ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituents of R ₁₆ , R ₁₇ and R ₁₉ include a methyl group, an ethyl group, an n-butyl group, a phenyl group, a 2-propenyl group and a benzyl group, and among them, R ₁₆ , R ₁₇ = -C ₂ H ₅ (ethyl group), R ₁₉ = -C
H ₃ (methyl group) is particularly preferred.

In the above formula [6], R ₁₈ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted Represents an alkoxy group.

Specific examples of the substituent of R ₁₈ include an ethoxy group, a chlorine atom, an ethyl group, an acetylamino group, an ethylsulfonylamino group, a methoxy group and the like. Among them, R ₁₈ = 3-OC ₂ H ₅ (Ethoxy group at atom position number 3) is particularly preferred. In addition, the number of substituents of R ₁₈ can be in the range of 1 to 4, which is a substitutable number in principle.

In the above formula [7], R ₂₀ and R ₂₁ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. Represents

Specific substituents for R ₂₀ and R ₂₁ include a methyl group, a 3-methylphenyl group, an n-butyl group,
Examples thereof include a phenyl group, a 2-propenyl group, and a benzyl group. Among them, R ₂₀ = -CH ₃ (methyl group), R ₂₁ = 3-
A methylphenyl group is particularly preferred.

Such a cyan dye is contained in the dye composition of the black dye layer in an amount of 40 to 60% by weight, preferably 50 to 6% by weight.
0 wt% is contained. If the content ratio is out of the above range, the storage stability will not be extremely lowered by a slight compositional change, as in the case of the yellow dye and the magenta dye, but rather the black dye will not be black.

Further, the black dye layer 12B contains a binder in addition to the above dyes. As the binder, any conventionally known resin binder can be used, and if preferable examples are shown, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose resins such as cellulose butyrate, polyvinyl alcohol, etc. , Polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone,
Examples thereof include vinyl resins such as polyacrylamide, polyester and the like. Of these, cellulose-based, acetal-based, butyral-based, polyester-based, and the like are particularly preferable from the viewpoint of heat resistance, dye migration, and the like.

The black dye layer of the present invention is basically formed of the above-mentioned materials, but may also contain various known additives as necessary and within the range not departing from the object of the present invention. May be.

Such a dye layer is usually prepared by adding the above-mentioned dye, binder resin, and other optional components to dissolve or disperse each component to prepare a coating liquid (ink).
This coating liquid is applied and dried on the base material sheet to form.

The thickness of the dye layer thus formed is
The thickness is 0.1 to 10 μm, preferably 0.2 to 3.0 μm.

The above-mentioned dye in the black dye layer is 20 to 80 wt%, preferably 40 to 70 wt% in terms of solid content.
It is said that

In such a black dye layer, in order to adjust coating suitability and prevent fusion with the image receiving sheet,
Organic fine particles such as polyethylene wax and inorganic fine particles may be contained in the dye layer.

An anti-sticking layer, that is, a release layer may be provided on such a black dye layer. As the release layer,
Examples thereof include those to which an anti-adhesive inorganic powder is attached, or resin layers having excellent releasability such as silicone polymers, acrylic polymers and fluorinated polymers. It should be noted that such a material having an excellent releasability can obtain a good effect even if it is contained in the dye layer.

Further, a heat-resistant layer may be provided on the back surface of such a thermal transfer sheet in order to avoid adverse effects due to the heat of the thermal head. As the heat-resistant layer, for example,
The reaction product of polyvinyl butyral and isocyanates may be provided with a layer containing a filler such as talc as a surfactant such as an alkali metal salt or an alkaline earth metal salt of a phosphoric acid ester.

By the way, the black dye layer 12B described above.
In addition, as the dye contained in the yellow dye layer 12Y, the cyan dye layer 12C, and the magenta dye layer 12M, which are usually provided on the base material sheet 11, the dye used in the conventional thermal transfer sheet is used as it is. It is possible, and there is no particular limitation.

The thermal transfer sheet of the present invention described above is used so that heat is applied from the back side of the thermal transfer sheet by the thermal head to transfer a large number of color dots of three or four colors to the image receiving paper (transferring material). As a result, a full-color image is formed on the image receiving paper (transferred material). The image receiving paper (transferred material) is
It comprises a substrate and a so-called receiving layer formed thereon for receiving the sublimable dye and maintaining the formed pixels. As the resin for forming the receiving layer, for example, polyolefin resin such as polypropylene, polyvinyl chloride, halogenated polymer such as polyvinylidene chloride,
Polyvinyl acetate, vinyl polymers such as polyacrylic esters, polyethylene terephthalate, polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, Examples thereof include ionomers, cellulosic resins such as cellulose diacetate, and polycarbonates.

The receptive layer is formed by coating and drying the ink prepared by dissolving or dispersing the above resin with necessary additives in a suitable solvent on a substrate by a known means. To be done. As the additive to be contained in the receiving layer,
Pigments such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, fine powder silica, etc. for the purpose of improving the whiteness of the receiving layer to further enhance the clarity of the transferred image and improving the film breakage of the receiving layer. And fillers can be used.

Hereinafter, the present invention will be described in more detail by showing specific examples. (Example) Preparation of 7 kinds of dyes used in the present invention as shown in the following formulas [1 ^* ] to [7 ^* ] and a total of 8 kinds of comparative magenta dyes represented by the formula [M ^* ] did.

[0068]

[Chemical formula 22]

[0069]

[Chemical formula 23]

[0070]

[Chemical formula 24]

[0071]

[Chemical 25]

[0072]

[Chemical formula 26]

[0073]

[Chemical 27]

[0074]

[Chemical 28]

[0075]

[Chemical 29] These dyes were appropriately combined to prepare a black dye as shown in Table 1 below.

[0076]

[Table 1] Using variously prepared black dyes, polyvinyl acetal resin, polyvinyl butyral resin, ethyl cellulose resin and the like as a binder, and toluene, methyl ethyl ketone, DMF (N, N-dimethylformamide) and the like as a solvent, An ink composition for forming the black dye layer 12B was prepared at the compounding ratio shown.

Black Dye Layer Ink Composition 1 / Black Dye No. 1 (Table 1) ... 8.00 parts by weight Polyvinyl acetal resin ... 3.50 parts by weight Toluene ... 43.25 parts by weight Methyl ethyl ketone ... 43.25 parts by weight DMF ... 2.00 parts by weight Black dye layer ink composition No. 2 / Black dye No. 2 (Table 1) ... 8.00 parts by weight Polyvinyl butyral resin ... 3.50 parts by weight Toluene ... 43.25 parts by weight Methyl ethyl ketone ... 43.25 parts by weight DMF ... 2.00 parts by weight Black dye layer ink composition No. 3 / Black dye No. 3 (Table 1) ... 8.00 parts by weight-Ethyl cellulose resin ... 3.50 parts by weight-Toluene ... 43.25 parts by weight-Methyl ethyl ketone ... 43.25 parts by weight-DMF ... 2.00 parts by weight Black dye layer ink composition 4. Black dye No. 4 (Table 1) 8.00 parts by weight Polyvinyl acetal resin 3.50 parts by weight Toluene 43.25 parts by weight Methyl ethyl ketone 43.25 parts by weight DMF 2.00 parts by weight Black dye layer ink composition No. 5 / Black dye No. 5 (Table 1) 8.00 parts by weight Polyvinyl butyral resin 3.50 parts by weight Toluene 43.25 parts by weight Methyl ethyl ketone 43.25 parts by weight DMF 2.00 parts by weight Black dye layer ink composition No. 6 / Black dye No. 6 (Table 1) ... 8.00 parts by weight-Ethyl cellulose resin ... 3.50 parts by weight-Toluene ... 43.25 parts by weight-Methyl ethyl ketone ... 43.25 parts by weight-DMF ... 2.00 parts by weight Black dye layer ink composition 7. Black dye No. 7 (Table 1) ... 8.00 parts by weight Polyvinyl acetal resin ... 3.50 parts by weight Toluene ... 43.25 parts by weight Methyl ethyl ketone ... 43.25 parts by weight DMF ... 2.00 parts by weight Black dye layer ink composition Item 8 / Black Dye No. 8 (Table 1) ... 8.00 parts by weight Polyvinyl acetal resin ... 3.50 parts by weight Toluene ... 43.25 parts by weight Methyl ethyl ketone ... 43.25 parts by weight DMF ... 2.00 parts by weight Black dye layer ink composition No. 9 / Black dye No. 9 (Table 1) ... 8.40 parts by weight Polyvinyl acetal resin ... 3.80 parts by weight Toluene ... 41.40 parts by weight Methyl ethyl ketone ... 41.40 parts by weight DMF ... 5.00 parts by weight These ink compositions Was applied onto a polyethylene terephthalate base sheet having a thickness of 6.0 μm so as to have a dry coating amount of 1.2 g / m ² and dried to obtain a transfer sheet sample having the above various black dye layers. Obtained. The thermal transfer sheet sample No. Is the black dye N
o. Corresponds to (Table 1).

Then, an image receiving paper was prepared in the following manner.

Preparation of image-receiving paper : Polyester resin (Voylon 600, manufactured by Toyobo Co., Ltd.) 4.0 parts by weight Vinyl chloride-vinyl acetate copolymer (1000A, manufactured by Denki Kagaku Kogyo Co., Ltd.) 6.0 Parts by weight ・ Amino-modified silicone oil (X-22-3050C, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 parts by weight ・ Epoxy-modified silicone oil (X-22-3000E, manufactured by Shin-Etsu Chemical Co., Ltd.) 0 .2 parts by weight Methyl ethyl ketone 44.8 parts by weight Toluene 44.8 parts by weight A coating solution for forming the receiving layer was prepared by using synthetic paper (Yuji EPG150, manufactured by Oji Yuka Co., Ltd.) as a base material. An image-receiving paper was prepared by coating and drying on one surface (4.5 g / m ² when dried).

On this image-receiving paper, an image was actually printed using the thermal transfer sheet having the black dye layer prepared above,
The following items were evaluated. (1) Relative sensitivity Gradation printing of 16 gradations (maximum applied energy: 100
mJ / mm ² (when the pulse width is 16 msec), and based on this printing, the applied energy (printing time) is plotted on the horizontal axis.
A so-called γ curve in which the vertical axis represents the optical density value (OD value) is drawn, and the printing energy when the optical density becomes 1.0 is determined by the comparative example sample (Sample No. 9). The optical density of each of the example samples (Sample Nos. 1 to 8) was determined, and the optical density values were relatively evaluated. (2) Maximum Density of Black The maximum density of the printed portion was measured by using -RD918 manufactured by Macbeth. The printing conditions are as follows: printing cycle 33.3 msec
/ line, pulse width 1-16msec / line, applied voltage 11.0V
Then, gradation printing of 16 gradations (maximum applied energy:
100 mJ / mm ² (when pulse width is 16 msec) was performed, and based on this printing, the applied energy (printing time) was plotted on the horizontal axis and the optical density value (OD value) was plotted on the vertical axis. The optical density value was defined as the maximum density. (3) Film Contamination Property Under the conditions of 60 ° C., 48 hours, and 40 g / cm ² , the dye surface and the back surface were overlapped with each other, and the set-off to the back surface was evaluated.

Criteria for evaluation: ◯ ... Large set-off on back surface (staining property) x: Small set-off on back surface (staining property) The results of these experiments are shown in Table 2 below.

[0082]

[Table 2]

[0083]

The effects of the present invention are clear from the above results. That is, since the black dye layer of the thermal transfer sheet of the present invention contains the black hue dye obtained by selecting and mixing the predetermined dyes, the content of the dye is particularly suppressed, and the staining property is reduced. Further, the recording sensitivity is good and the black density is high.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a thermal transfer sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet 11 ... Substrate sheet 12 ... Dye layer 12B ... Black dye layer 12M ... Magenta dye layer 12Y ... Yellow dye layer 12C ... Cyan dye layer

Claims (2)

[Claims] 1. A thermal transfer sheet having a black dye layer on a base sheet, wherein the black dye layer comprises at least one of the yellow dyes represented by the following formulas [1] and [2]: A magenta dye represented by the formula [3] and at least one cyan dye selected from the following formula [4], formula [5], formula [6] and formula [7]: A thermal transfer sheet. [Chemical 1] (In the formula [1], R ₁ and R ₂ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₃ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group. ] (In the formula [2], R ₄ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, and R ₅ is Represents a hydrogen atom, a halogen atom, a substituted or unsubstituted arylalkoxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted alkyl group. (In the formula [3], R ₆ and R ₇ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₈ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.) ] (In the formula [4], R ₉ , R ₁₀ and R ₁₂ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. the stands, R ₁₁ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group. ) [Chemical 5] (In the formula [5], R ₁₃ and R ₁₄ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, R ₁₅ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group.) ] (In the formula [6], R ₁₆ , R ₁₇ and R ₁₉ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. the stands, R ₁₈ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted acylamino group, a substituted or unsubstituted sulfonylamino group, or a substituted or unsubstituted alkoxy group. ) [Chemical 7] (In the formula [7], R ₂₀ and R ₂₁ each represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group. ) 2. The dye composition contained in the black dye layer contains 10 to 20 wt% of yellow dye, 25 to 35 wt% of magenta dye, and 50 to 60 wt% of cyan dye. Item 2. A thermal transfer sheet according to item 1.