JPH07304272A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To enhance the recording sensitivity and black density of a black type thermal transfer sheet by using specific types of yellow dye, magenta dye and cyan dye to form a dye layer of the sheet. CONSTITUTION:A black type thermal transfer sheet comprises a base sheet and a dye layer that contains a plurality of dyes and is provided on one of the side surfaces of the base sheet. The dye layer contains at least one yellow dye selected from the compound group represented by formula I or the like, at least one magenta dye selected from the compound group represented by formula II or the like, and at least one cyan dye selected from the compound group represented by formula III or the like. In the formulas: R1, R2 are alkyl groups, aryl groups, aryl groups or the like; R3 is an alkyl group, an alkoxy group, an alkylcarbonylamino group or the like; R4 is an alkyl group, an aralkyloxycarbonyl group, an alkoxycarbonylamino group or the like; R5 is an alkyl group, an aryl group or the like; R6 is an alkylaminocarbonyl group, an alkylsulfonylamino group or the like; R7 is an alkoxy group or the like; and X is a halogen atom.

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, and more specifically, it is an object of the present invention to provide a thermal transfer sheet capable of forming a black image having excellent color density and various fastnesses.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a method of forming various full-color images on paper or a plastic film by using a thermal transfer system using a sublimable dye. In this case, the thermal head of the printer is used as the heating means, and by heating for an extremely short time, the four color dots of the three primary colors or the black of the three primary colors are transferred to the thermal transfer image-receiving sheet, and the multicolored color dots are transferred. To reproduce the full-color image of the original. Further, only one color such as black is transferred to the thermal transfer image receiving sheet to reproduce a high gradation monochrome image. The image formed in this way is very clear because the coloring material used is a dye and has excellent transparency, so the obtained image has excellent color reproducibility and gradation of intermediate colors, It is similar to the image by conventional offset printing or gravure printing,
Moreover, it is possible to form high-quality images and monochrome images comparable to full-color photographic images. As such a black type thermal transfer sheet, JP-A-5-201147, JP-A-5-238029 and JP-A-6-92046 are known.

[0003]

However, the conventional black type thermal transfer sheet used in the thermal transfer method is not suitable for the combination of the three primary colors of yellow, magenta and cyan, and therefore is excellent in color density and various fastnesses. It wasn't something. Therefore, an object of the present invention is to provide a thermal transfer sheet capable of forming a black image having excellent color density and various fastnesses.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention provides a black thermal transfer sheet in which a dye layer containing a plurality of dyes is provided on one surface of a substrate sheet, wherein the dye layer is represented by the following general formulas (1), (2) and (3). At least one yellow dye selected from the general formulas (4), (5) and (6)
A thermal transfer sheet containing at least one magenta dye selected from among the above and at least one cyan dye selected from the general formulas (7), (8) and (9): is there.

[Chemical 13]

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21] (In the formulas (1) to (9), R ₁ and R ₂ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group. Represents a substituted or unsubstituted alkoxyalkyl group, or a substituted or unsubstituted aralkyl group, R ₃ is a substituted or unsubstituted alkyl group,
A substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, a substituted or unsubstituted unsubstituted alkylaminocarbonyl group, a cyano group, a nitro group, a halogen atom or Represents a hydrogen atom, R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted An alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom, R
₅ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom, R ₆ represents a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group or a halogen atom, and R ₇ is It represents a substituted or unsubstituted alkyl group, and X represents a halogen atom. )

[0005]

[Function] By using a combination of specific dyes,
It is possible to provide a thermal transfer sheet capable of forming a black image having excellent color density and various fastnesses.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an example of a schematic sectional view of a thermal transfer sheet of the present invention. In FIG. 1, a thermal transfer sheet 1 includes a base sheet 11 and a dye layer 1 of each color on one surface of the base sheet 11.
2 is a thermal transfer sheet provided with 2. And the transfer dye layer 1
2 is usually a yellow dye layer 12Y and a magenta dye layer 1
2M, 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. Further, even a thermal transfer sheet in which the black dye layer alone is provided on one surface of the base sheet is a preferred embodiment of the present invention.

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 substrate 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, the following general formulas (1) and (2) are used.
Alternatively, at least one of the yellow dyes represented by (3) is used.

[0013]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

In the general formula (1), R ₁ and R ₂ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group,
It represents a substituted or unsubstituted cycloalkyl group or a substituted or unsubstituted aralkyl group.

Specific substituents for R ₁ and R ₂ include:
Ethyl group, 4-cyclohexylphenoxyethyl group, n
-Butyl group, phenyl group, 2-propenyl group, benzyl group and the like, among which R ₁ = ethyl group, R ₂ = 4-
A cyclohexylphenoxyethyl group is particularly preferred.

In the general formula (1), R ₃ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, a substituted or unsubstituted alkoxy group, a cyano group, or a nitro 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 general formula (2), R ₁ is 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. Represent

Specific examples of the substituent of R ₁ 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 general formula (2), R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylamino group. It represents a carbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom.

Specific examples of the substituent of R ₄ 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. In addition, the number of the substituents of R ₄ can be in the range of 1 to 5, which is a substitutable number in principle.

In the general formula (3), R ₁ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aralkyl group or a substituted group. Alternatively, it represents an unsubstituted alkoxyalkyl group.

Specific R ₁ is methyl group, n-butyl group, phenyl group, 2-propenyl group, benzyl group,
_{-CH 2 CH 2 CH 2 OCH (} CH 3) 2 and the like, among _{-CH 2 CH 2 CH 2 OCH (} CH 3) 2 are particularly preferred.

In the above general formula (3), R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylamino. It represents a carbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom.

Specific examples of R ₄ include a methyl group, a cyano group, a chlorine atom, a hydrogen atom and the like. Among them, when R ₄ is a hydrogen atom, it is particularly preferable.

Such a yellow dye is contained in the dye composition of the black dye layer in an amount of 5 to 50% by weight, preferably 10 to 40% by weight.
Wt% is contained. When this content rate is out of the upper limit range,
Even if the composition is changed to some extent, the storability is not extremely deteriorated, but rather the disadvantage that it is not black occurs.

Next, the magenta dye contained in the black dye layer 12B of the present invention is represented by the following general formulas (4) and (5).
Alternatively, at least one of the magenta dyes represented by (6) is used.

[0028]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

In the above general formula (4), R ₁ and R ₂ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituent of R ₁ and R ₂ include an ethyl group, an n-butyl group, a phenyl group, a cyclohexyl group, a 2-propenyl group and a benzyl group.
Among them, R ₁ = R ₂ = ethyl group is particularly preferable.

In the general formula (4), R ₃ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, It represents a substituted or unsubstituted unsubstituted alkylaminocarbonyl group.

Specific examples of the substituent of R ₃ include a methyl group, an ethyl group, a methoxy group, —CONHC ₃ H ₇ and —N.
HCOCH _3, -NHSO ₂ CH _3, and among them R ₃ = methyl group is particularly preferred.

In the general formula (4), R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group. Represents a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom.

Specific examples of the substituent of R ₄ include a hydrogen atom, a methyl group, —NHCOCH ₃ , —NHSO ₂ CH ₃
And the like, among which R ₄ = hydrogen atom is particularly preferable.

In the general formula (4), R ₅ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted cycloalkyl group, a cyano group, Represents a nitro group, a halogen atom or a hydrogen atom.

As a specific substituent of R ₅ , a methyl group,
Examples thereof include an ethyl group and a phenyl group, and among them, R ₅ = methyl group is particularly preferable.

In the above general formula (5), R ₁ and R ₂ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituents of R ₁ and R ₂ include an ethyl group, an n-butyl group, a phenyl group, a 2-propenyl group and a benzyl group. Among them, R ₁ = ethyl group, a benzyl group, R ₂ = ethyl group and 2-propenyl group are particularly preferable.

In the general formula (5), R ₃ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, It represents a substituted or unsubstituted unsubstituted alkylaminocarbonyl group.

As a specific substituent of R ₃ , a methyl group,
Ethyl group, a methoxy group, -NHCOCH _3, -NHSO
₂ CH _{3 and the} like, among which R = -NHSO ₂ CH
_3, -NHCOCH ₃ is particularly preferred.

In the general formula (5), R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group. Represents a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom.

Specific examples of the substituent of R ₄ include a methyl group, an ethyl group, a methoxy group, a cyclohexyl group, and —SO.
₂ NHCH ₃ , a cyano group, a nitro group, a chlorine atom, a hydrogen atom, and the like, among which R ₄ = methyl group, cyano group,
A nitro group and a chlorine atom are particularly preferable.

In the above general formula (6), R ₁ and R ₂ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aralkyl group.

Specific examples of the substituent of R ₁ and R ₂ include an ethyl group, an n-butyl group, a phenyl group, a cyclohexyl group, a 2-propenyl group and a benzyl group.
Among them, R ₁ = R ₂ = ethyl group is particularly preferable.

In the general formula (6), R ₃ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, It represents a substituted or unsubstituted unsubstituted alkylaminocarbonyl group.

Specific examples of the substituent of R ₃ include a methyl group, an ethyl group, a methoxy group, —NHCOCH ₃ and —NH.
SO ₂ CH _{3 and the} like can be mentioned, and among them, R ₃ = methyl group is particularly preferable.

In the general formula (6), R ₅ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted cycloalkyl group, a cyano group, Represents a nitro group, a halogen atom and a hydrogen atom.

Specific examples of the substituent of R ₅ include a methyl group, a phenyl group, a 3-methylphenyl group, and a tert-butyl group. Among them, R ₅ = 3-methylphenyl group and a tert-butyl group are particularly preferable. preferable.

Such a magenta dye is contained in the dye composition of the black dye layer in an amount of 5 to 50% by weight, preferably 10 to 4% 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, 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 cyan dye selected from the following general formula (7), (8) or (9) is used. .

[0051]

[Chemical 28]

[Chemical 29]

[Chemical 30]

In the general formula (7), R ₁ and R ₂ are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group,
It represents a substituted or unsubstituted cycloalkyl group or a substituted or unsubstituted aralkyl group.

Specific examples of the substituent for R ₁ and R ₂ include an ethyl group, an n-butyl group, a 2-propenyl group and a benzyl group, and among them, R ₁ = R ₂ = ethyl group is particularly preferable.

In the general formula (7), R ₃ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group,
It represents a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, a substituted or unsubstituted alkoxy group, a cyano group, or a nitro group.

Specific examples of the substituent of R ₃ include a hydrogen atom, a methyl group, —NHCOCH ₃ , and —NHSO ₂ CH ₃
And the like, among which R ₃ = methyl group and hydrogen atom are particularly preferable.

In the above general formula (7), R ₆ is a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkyl Represents a sulfonylamino group or a halogen atom.

Specific examples of the substituent of R ₆ include -CON.
_{HCH 3, -SO 2 NHCH 3,} -NHCOC 2 H 5,
_{-NHCOC 3 H 7, -NHSO 2 CH} 3 , and among them _{R 6 = -NHCOCH 3, -NHCOC 2} H
_5, -NHCOC ₃ H ₇ it is particularly preferred.

In the above general formula (7), R ₇ represents a substituted or unsubstituted alkyl group, cyano group, nitro group, halogen atom or hydrogen atom. Specific examples of the substituent of R ₇ include a methyl group, an ethyl group, a chlorine atom and a hydrogen atom, and among them, R ₇ = methyl group and a hydrogen atom are particularly preferable.

In the above general formula (7), X represents a halogen atom or a hydrogen atom.

In the above general formula (8), R ₁ and R ₂ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aralkyl group.

Specific substituents for R ₁ and R ₂ include n-butyl group, n-hexyl group, phenyl group and 2-
Examples thereof include a propenyl group and a benzyl group, among which R ₁ =
_{R 2 = n-C 6 H} 13 (n- hexyl group) is particularly preferred.

In the above general formula (8), R ₃ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, It represents a substituted or unsubstituted unsubstituted alkylaminocarbonyl 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 general formula (8), R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group. Represents a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom.

Specific examples of the substituent of R ₄ include a methyl group, an ethyl group, —CONHCH ₃ , and —SO ₂ NHC.
Among them, H ₃ , cyano group, nitro group, halogen group, hydrogen atom and the like can be mentioned, and R ₄ = hydrogen atom is particularly preferable.

In the above general formula (9), R ₁ and R ₂ are
It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aralkyl group.

Specific substituents for R ₁ and R ₂ include methyl group, 3-methylphenyl group, n-butyl group,
Examples thereof include a phenyl group, a 2-propenyl group and a benzyl group, and among them, R ₁ = -CH ₃ (methyl group) and R ₂ = 3-methylphenyl group are particularly preferable.

Such a cyan dye is contained in the dye composition of the black dye layer in an amount of 30 to 75% by weight, preferably 40 to 70% by weight.
Wt% is contained. When this content rate is out of the above range,
Similarly to the case of the yellow dye and the magenta dye, a slight change in composition does not extremely reduce the storage stability, but rather causes a problem that the color is not black.

Further, the black dye layer 12B contains a binder together with the above dye. As a binder,
Any conventionally known resin binder can be used, and if preferable examples are shown, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose,
Cellulosic resins such as hydroxypropyl cellulose, methyl cellulose, cellulose acetate, butyrate cellulose,
Examples thereof include vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl acetoacetal, polyvinyl pyrrolidone and polyacrylamide, and polyester. 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.

In the present invention, the total amount of the dye added to the dye layer ink of the transfer sheet can be reduced as compared with the conventional case, so that the D / B ratio (D: weight of dye B: binder (Weight) It can be contained in a wide range of about 0.5 to 3.0, and desired print density and storability of the transfer sheet can be improved according to the purpose. The black dye layer of the present invention is basically formed of the above-mentioned materials, but may further contain various known additives as necessary and within the range not departing from the object of the present invention. . For example, European Patent Nos. 133011 and 13301.
No. 2 and No. 111004 are mentioned.

Such a dye layer is usually prepared by adding the above dye, binder resin and other optional components to dissolve or disperse each component to prepare a coating liquid (ink).
This coating solution is applied and dried on the base material sheet to form. The thickness of the dye layer thus obtained is 0.1 to
The thickness is 10 μm, preferably about 0.2 to 3.0 μm. Further, the dye in the black dye layer is 2 in terms of solid content.
The amount is 0 to 80 wt%, preferably 40 to 70 wt%.

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

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 inorganic powder having an anti-adhesion property is attached, or resin layers such as silicone polymers, acrylic polymers, and fluorinated polymers having excellent releasability. It should be noted that such a material having an excellent effect of 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, a layer containing a filler such as talc in a surfactant such as an alkali metal salt of a phosphoric acid ester or an alkaline earth metal salt in a reaction product of polyvinyl butyral and an isocyanate is provided. You can

By the way, the black dye layer 12B described above.
In addition to the above, usually, as the dye contained in the yellow dye layer 12Y, the magenta dye layer 12M, and the cyan dye layer 12C provided on the base sheet 11, the dye used in the conventional thermal transfer sheet is used as it is. You can
There is no particular limitation. As described above, the black thermal transfer sheet of the present invention has excellent sensitivity and high color developability. Therefore, in order to form a color image that has been conventionally printed by using this recording method, when a thermal transfer sheet having each of yellow, magenta, and cyan dye layers is used together, a black image that requires a high density of characters and borders is required. It is effective for forming the image, and particularly when used for proofreading, a black image excellent in color reproducibility can be obtained.

In the thermal transfer sheet of the present invention described above, thermal energy is applied from the back side by a thermal head so that multicolored dots of 3 or 4 colors are transferred to the image receiving paper (transferring material). Used, and as a result, a full-color image is formed on the image receiving paper (transferred material). The image receiving paper (transferred material) includes a base material and a so-called receiving layer formed on the base material for receiving the sublimable dye and maintaining the formed pixels.

As the resin for forming this receiving layer, for example, a polyolefin resin such as polypropylene,
Halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, vinyl polymers such as polyvinyl acetate and polyacrylic ester, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, ethylene and propylene, etc. Examples thereof include copolymer resins of olefins and other vinyl monomers, ionomers, cellulose resins such as cellulose diacetate, and polycarbonates.

The receptive layer is formed by coating and drying an 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 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.

[0079]

EXAMPLES The present invention will be described in more detail below by showing specific examples. As shown in the following formulas (Y1) to (C5), 12 kinds of dyes used in the present invention, and formula (M * 1), formula (M * 2), formula (Y * 1), formula (C *).
A total of 16 kinds of dyes of the comparative magenta dye, the yellow dye, and the cyan dye shown in 1) were prepared.

[0080]

[Chemical 31]

[Chemical 32]

[Chemical 33]

[Chemical 34]

[Chemical 35]

[Chemical 36]

[Chemical 37]

[Chemical 38]

[Chemical Formula 39]

[Chemical 40]

[Chemical 41]

[Chemical 42]

[Chemical 43]

[Chemical 44]

[Chemical formula 45]

[Chemical formula 46] These dyes were combined for convenience to prepare black dyes as shown in Tables 1 to 3 below. The numerical values in each table represent parts by weight.

[0081]

[Table 1]

[0082]

[Table 2]

[0083]

[Table 3]

An ink composition for forming the black dye layer 12B at the compounding ratios shown below using the variously prepared black dyes, polyvinyl acetoacetal resin as the binder, toluene, methyl ethyl ketone as the solvent, etc. Was produced.

Black Dye Layer Ink Compositions 1 to 5 Black Dye No. 1-5 (Table 1) 7.00 parts by weight-Polyvinyl acetoacetal resin 3.50 parts by weight (S-REC KS-5; manufactured by Sekisui Chemical Co., Ltd.)-Toluene 44.75 parts by weight-Methylethylketone 44.75 parts by weight Black dye layer ink Compositions 6-9 Black dye No. 6 to 9 (Table 2) 7.50 parts by weight Polyvinyl acetoacetal resin 3.50 parts by weight (S-REC KS-5; manufactured by Sekisui Chemical Co., Ltd.) Toluene 44.50 parts by weight Methyl ethyl ketone 44.50 parts by weight Black dye layer ink Compositions 10 to 11 ・ Black dye No. 10-11 (Tables 2-3) 7.70 parts by weight Polyvinyl acetoacetal resin 3.50 parts by weight (S-REC KS-5; manufactured by Sekisui Chemical Co., Ltd.) Toluene 44.40 parts by weight Methyl ethyl ketone 44.40 parts by weight Black dye Layer ink compositions 12 to 14 Black dye No. 12 to 14 (Table 3) 8.00 parts by weight Polyvinyl acetoacetal resin 3.50 parts by weight (S-REC KS-5; manufactured by Sekisui Chemical Co., Ltd.) Toluene 44.25 parts by weight Methyl ethyl ketone 44.25 parts by weight These ink compositions On the base material sheet (6CF53; made by Toray) of polyethylene terephthalate having a thickness of 6.0 μm and heat-resistant lubricated, the dry coating amount is 1.2.
A transfer sheet sample having the above-mentioned various black dye layers was obtained by coating and drying so as to be g / m ² . The thermal transfer sheet sample No. Is the black dye No. Corresponds to (Table 1).

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

Preparation of image-receiving paper ・ Polyester resin (VYLON600; 4.0 parts by weight manufactured by Toyobo) ・ 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 0.8 parts by weight The coating liquid for forming the receiving layer was applied on one surface of synthetic paper (Yupo FPG150; manufactured by Oji Yuka) as a substrate and dried to prepare an image receiving paper. (4.5g / m ² when dry)

The following items were evaluated by actually printing on this image-receiving paper using the thermal transfer sheet having the black dye layer prepared above. (1) Relative sensitivity Gradation printing of 16 gradations (maximum applied energy: 100
mJ / mm ² , pulse width 16 msec),
Based on this printing, a so-called γ-curve was drawn, in which the horizontal axis represents the applied energy (printing time) and the vertical axis represents the optical density value (OD value), and a comparative example sample (Sample No. 1) was drawn.
In 2), the printing energy when the optical density becomes 1.0 is determined, and the optical density of each of the example samples (Sample Nos. 1 to 11) at this printing energy is calculated to obtain the optical density value. Was evaluated relatively. (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 ms
ec / line, pulse width 1 to 16 msec / lin
By applying a voltage of 11.0V and adjusting the application time with a constant voltage, gradation printing of 16 gradations (maximum applied energy: 100 mJ / mm ² , pulse width 16 msec) is performed. And, the horizontal axis represents applied energy (printing time) and the vertical axis represents optical density (OD
Value), the maximum optical density of the so-called γ curve is defined as the maximum density.

[0089]

[Table 4]

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 dye amount in the dye layer of the dye is suppressed, and the recording sensitivity is improved. Has an excellent effect and a high black density.

[Brief description of drawings]

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

[Explanation of symbols]

 1-Thermal transfer sheet 11-Base material sheet 12-Dye layer 12B-Black dye layer 12M-Magenta dye layer 12Y-Yellow dye layer 12C-Cyan dye layer

Claims (4)

[Claims] 1. A black thermal transfer sheet comprising a substrate sheet and a dye layer containing a plurality of dyes on one surface thereof, wherein the dye layer is represented by the following general formulas (1), (2) and (3).
At least one yellow dye selected from among the above, at least one magenta dye selected from the general formulas (4), (5) and (6), and general colors (7), (8) and A thermal transfer sheet containing at least one cyan dye selected from (9). [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] [Chemical 5] [Chemical 6] [Chemical 7] [Chemical 8] [Chemical 9] (In the formulas (1) to (9), R ₁ and R ₂ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group. Represents a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkoxyalkyl group, R ₃ is a substituted or unsubstituted alkyl group,
A substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group, a substituted or unsubstituted unsubstituted alkylaminocarbonyl group, a cyano group, a nitro group, a halogen atom or Represents a hydrogen atom, R ₄ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyloxycarbonyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted Represents an alkoxy group, a substituted or unsubstituted alkylaminosulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group or a halogen atom, and R ₅ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl Group, substituted or non- A substituted amino group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group, a halogen atom or a hydrogen atom, R ₆ represents a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkylaminosulfonyl group Represents a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonylamino group or a halogen atom, R7 represents a substituted or unsubstituted alkyl group, X
Represents a halogen atom. ) 2. The dye contained in the dye layer is represented by the following formula Y:
-1, Y-2 and Y-3, at least one yellow dye selected from the following formulas M-1, M-2 and M-3,
From at least one magenta dye selected from M-4 and at least one cyan dye selected from the following formulas C-1, C-2, C-3, C-4 and C-5 The thermal transfer sheet according to claim 1, wherein [Chemical 10] [Chemical 11] [Chemical 12] 3. The dye contained in the dye layer is represented by the following formula Y:
-2, a yellow dye, a magenta dye of the following formula M-4, and at least one cyan dye selected from the following formulas C-1 and C-4. [Chemical 47] 4. The dye composition contained in the dye layer comprises 10 to 40 wt% of yellow dye and 10 of magenta dye.
4. The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet contains 40 to 70 wt% of cyan dye and 40 to 70 wt% of cyan dye.