JP3258775B2 - Thermal transfer sheet - Google Patents

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 particularly to a thermal transfer sheet having a magenta dye layer containing a magenta hue dye excellent in skin color reproducibility (having a wide reproduction range and obtaining a clear color). Regarding the sheet.

[0002]

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

[0003]

However, the reproducibility of the flesh color, especially for consumer use, is the reproducibility of the flesh color (ie, having a wide reproduction range and obtaining a clear color).
However, despite the demands of the above, at present, it can be said that various types of thermal transfer sheet samples presented heretofore cannot provide sufficiently satisfactory skin color reproducibility.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a thermal transfer sheet having a magenta dye layer exhibiting an extremely excellent effect on skin color reproducibility. .

[0005]

In order to achieve the above object, a thermal transfer sheet according to the present invention is a thermal transfer sheet having a magenta dye layer on a base sheet, wherein the magenta dye layer comprises: A magenta hue dye obtained by mixing the dyes represented by the formulas [1] and [2] in a weight content ratio of 10:90 to 50:50, and polyethylene wax particles. did.

[0006]

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[0007]

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[0008]

The dye layer of the thermal transfer sheet of the present invention, particularly the magenta dye layer, contains a magenta hue dye obtained by mixing a predetermined dye, so that the color density can be maintained while maintaining the color density.
A high saturation and a magenta hue slightly approaching the yellow hue are obtained, and when this is used to reproduce a skin color, a clear color can be realized while having a wide skin color reproduction range.

[0009]

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, a thermal transfer sheet 1 is a base sheet 1
1 and a thermal transfer sheet provided with a dye layer 12 of each color on one surface of a substrate sheet 11. Then, the transfer dye layer 12
Is usually a yellow dye layer 12Y, a magenta dye layer 12
M and cyan dye layers 12C are arranged repeatedly.

The individual dye layers 12C, 12C
M and the width of the dye layer 12Y may be the width actually required for one image formation, or may be an integral multiple thereof, and can be appropriately determined based on the size of the screen to be formed.

As the base sheet 11, a base sheet used for a 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 films such as ionomers, glassine paper,
Papers such as condenser paper and paraffin paper, and nonwoven fabrics are preferably used. Further, these composites can be used as a base sheet.

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

On such a substrate sheet, a magenta dye layer 12M is formed as one of the dye layers 12 as described above. The magenta dye layer 12M is a layer in which a magenta hue dye is supported by a binder.

The magenta hue dye contained in the magenta dye layer 12M of the present invention is obtained by mixing the dyes represented by the following formulas [1] and [2].

[0016]

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[0017]

Embedded image The weight content ratio of the dyes of the formula [1] and the formula [2] is 10:90 to 50:50, and not only the flesh color reproducibility but also the sufficient density coloring property when black is printed. Considering this, it is preferably within the range of 30:70 to 50:50, more preferably 35:65 to 45:55.

If the amount of the dye represented by the formula [1] becomes too small and becomes less than 10 wt%, there arises a disadvantage that a sufficient black density cannot be obtained when three colors are overprinted. If the amount of the dye represented by 1) is too large and exceeds 50% by weight, the solubility of the solvent will be low, and there will be a disadvantage that an ink composition in which a sufficient amount of the dye is dissolved for color development cannot be prepared.

It is preferable that such a magenta hue dye further contains a dye represented by the following formula [3].

[0020]

Embedded image This is to increase the maximum black density value when reproducing black by superimposing magenta, yellow and cyan. The dye represented by the formula [3] is obtained by the above formulas [1] and [2]
Is contained in an amount of 5 to 30 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the total amount of the dye.
If this value is less than 5 parts by weight, there arises a disadvantage that a sufficient black density cannot be obtained when three colors are superimposed and printed, and if this value exceeds 30 parts by weight, excellent skin color reproducibility cannot be obtained. (The reproduction range becomes narrower and the color becomes muddy.)
Inconvenience occurs.

The magenta dye layer 12M containing such a magenta hue dye further contains organic particles such as polyethylene wax. This is for improving the coating suitability of the dye layer on the base sheet and preventing the dye layer from fusing with the back heat-resistant layer facing the transfer sheet during winding and preservation. Further, by adding these particles, it is possible to control the coefficient of friction between the image receiving sheet receiving layer and the transfer sheet dye layer during printing, and it is possible to prevent print wrinkles. In addition, as the organic particles as described above, it is also preferable to use a combination of fine particles having a particle diameter of 1.0 μm or less and thermally fusible particles having a particle diameter of 5 to 15 μm. The content of the organic particles as described above in the dye layer is 0.3 to 8.0% by weight, preferably 0.1% by weight, based on the total solid content of the dye and the binder resin described below.
It is appropriate to contain it at a ratio of 5 to 7.0% by weight.

Further, the magenta dye layer 12M contains a binder. As the binder, any of conventionally known resin binders can be used, and preferred examples thereof include ethyl cellulose, hydroxyethyl cellulose,
Cellulose-based resins such as ethylhydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, and cellulose butyrate; vinyl-based resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide; and polyesters. . Among them, cellulose-based, acetal-based, butyral-based, and polyester-based are particularly preferable from the viewpoints of heat resistance, dye transferability, and the like.

The magenta dye layer of the present invention basically comprises
Although formed from the above-described materials, various other known additives may be contained as necessary and without departing from the purpose of the present invention.

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

The thickness of the dye layer thus formed is
The thickness is about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm.

The dye in the magenta dye layer is 5 to 70% by weight, preferably 10 to 60% by weight in terms of solid content.
%.

The monochromatic print of the magenta dye layer thus formed has the following physical properties. That is, CIE1976L ^* a ^* b ^* dye system (JIS Z
8729-1980), when L ^* (brightness index) = 50, it is necessary to blend the magenta hue dye so that C ^* > 80 and 340 ° <H ° <359 °. By satisfying this range, good skin color reproducibility can be obtained. The definitions of L ^* , C ^* , and H ° are as follows.

The above L ^* is a lightness index, and is defined as follows.

L ^* = 116 (Y / Y ₀ ) ^1/3 -16 where (Y / Y ₀ )> 0.008856 L ^* = 903.29 (Y / Y ₀ ) where (Y / Y ₀ ) When ≦ 0.008856, Y is the tristimulus value of the sample in the XYZ color system, Y ₀
Represents the tristimulus value of the illumination light source.

The above C ^* represents the metric chroma and is defined as follows.

C ^* = [(a ^* ) ² + (b ^* ) ² ] ^{1/2 The} above H ° represents a hue angle and is defined as follows.

When a ^* > 0 and b ^* > 0, H ° = tan
^-1 (b ^* / a ^* ) [degree] When a ^* > 0 and b ^* <0, H ° = 360 ° + tan ⁻¹ (b ^*
/ A ^* ) [degree] When a ^* <0, H ° = 180 ° + tan ⁻¹ (b ^*
/ A ^* ) [degree] When a ^* = 0, b ^* = 0, H ° = 0 ° a ^* = 0, when b ^* > 0, H ° = 90 ° a ^* = 0, b ^* <0 In this case, H ° = 270 ° Note that the above a ^* and b ^* are called chromaticness indices and are defined as follows.

A ^* = 500 [(X / X ₀ ) ^1/3 − (Y / Y ₀ ) ^1/3 ] b ^* = 200 [(Y / Y ₀ ) ^1/3 − (Z / Z ₀ ) ^{1 / 3} ] where X / X ₀ > 0.008856, Y / Y ₀ > 0.008856, Z
/ Z ₀ > 0.008856 Here, XYZ is a tristimulus value in the XYZ color system of the sample,
X ₀ Y ₀ Z ₀ represents the tristimulus value of the illumination light source. Where X
If / X ₀ , Y / Y ₀ , and Z / Z ₀ include 0.008856 or less, calculation is performed by replacing the corresponding cubic root terms in the above equation with the following equations.

7.787 (X / X ₀ ) + (16/116) 7.787 (Y / Y ₀ ) + (16/116) 7.787 (Z / Z ₀ ) + (16/116) An anti-adhesion layer, that is, a release layer, may be provided on the magenta dye layer having various characteristics. Examples of the release layer include a layer to which an inorganic powder having an anti-adhesive property is adhered, and a resin layer having excellent release properties such as a silicone polymer, an acrylic polymer, and a fluorinated polymer. It should be noted that such a material having an excellent releasing property can provide 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.

Incidentally, in addition to the above-described magenta dye layer 12M, the dye contained in the yellow dye layer 12Y and the cyan dye layer 12C provided on the base sheet 11 is usually used in a conventional thermal transfer sheet. The dye used can be used as it is, and is not particularly limited. For example, preferred dyes include yellow dyes such as Holon Brilliant Yellow 6GL, PTY-52, Macrolex Yellow 6G, and the like. , MS Blue 100, those represented by the following formula [5], and the following formula [6]. As a binder for supporting these dyes, various resin binders are used as described above.

[0037]

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[0038]

Embedded image The above-described thermal transfer sheet of the present invention is used to transfer a large number of color dots of three or four colors to an image receiving paper (transfer material) by applying heat from the back side by a thermal head, and as a result, A full-color image is formed on the image receiving paper (transfer material). The image receiving paper (transfer receiving 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. Examples of the resin for forming the receiving layer include polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, vinyl polymers such as polyvinyl acetate and polyacrylic ester, polyethylene terephthalate, and polybutylene. Polyester resins such as terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, ionomers,
Cellulose-based resins such as cellulose diacetate, polycarbonate and the like can be mentioned.

The receptor layer is formed by applying and drying an ink prepared by dissolving or dispersing the above-mentioned resin with necessary additives in an appropriate solvent on a substrate by a known means. Is done. As an additive to be contained in the receiving layer,
Pigments such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, fine powdered silica, etc. for the purpose of improving the whiteness of the receiving layer to further enhance the sharpness of the transferred image and improving the cutness of the receiving layer. And fillers can be used.

Hereinafter, the present invention will be described in more detail with reference to specific experimental examples. Experimental Examples As shown in Table 1 below, various magenta hue dyes were prepared by appropriately using 1 to 4 dyes. Table 1
In the formula, the dyes of the formulas [1] to [3] represent the dyes described above, respectively, and the dye of the formula [4] represents the dye represented by the structural formula of the following formula [4].

[0041]

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[0042]

[Table 1] Using such various magenta hue dyes, polyvinyl acetal as a binder, a mixed solvent of methyl ethyl ketone-toluene as a solvent (1: 1 mixture by weight ratio), and polyethylene wax as a filler, the compounding ratio shown below: Magenta dye layer 12
Ink compositions 1 to 13 for forming M were prepared.

Magenta dye layer ink composition 1 · Magenta hue dye sample No. 1 6.0 parts · Polyvinyl acetal 3.5 parts · Solvent 90.5 parts · Polyethylene wax 0.05 parts Magenta dye layer ink composition 2 · Magenta hue dye sample No.2 6.0 parts ・ Polyvinyl acetal 3.5 parts ・ Solvent 90.5 parts ・ Polyethylene wax 0.05 parts Magenta dye layer ink composition 3・ Magenta hue dye sample No.3 6.0 parts -Polyvinyl acetal 3.5 parts-Solvent 90.5 parts-Polyethylene wax 0.05 parts Magenta dye layer ink composition 4 -Magenta hue dye sample No. 4 6.0 parts-Polyvinyl acetal 3.5 parts-Solvent 90. 5 parts polyethylene wax 0.05 part of the magenta dye layer ink composition 5 magenta hue dye sample No. 6.0 parts Polyvinyl acetal 3.5 parts Solvent 90.5 parts Polyethylene wax 0.05 part of the magenta dye layer ink composition 6 Magenta hue dye sample No. 6 6.0 parts Polyvinyl acetal 3.5 parts -Solvent 90.5 parts-Polyethylene wax 0.05 parts Magenta dye layer ink composition 7 -Magenta hue dye sample No. 7 6.0 parts-Polyvinyl acetal 3.5 parts-Solvent 90.5 parts-Polyethylene wax 0. 05 parts Magenta dye layer ink composition 8 • Magenta hue dye sample No. 8 6.0 parts • Polyvinyl acetal 3.5 parts • Solvent 90.5 parts • Polyethylene wax 0.05 parts Magenta dye layer ink composition 9 (Comparative・ Magenta hue dye sample No. 9 4.0 parts ・ Polyvinyl acetal 3.5 parts ・ Solvent 92.5 parts Polyethylene wax 0.23 parts Magenta dye layer ink composition 10 (Comparative) Magenta hue dye sample No. 10 6.0 parts Polyvinyl acetal 3.5 parts Solvent 90.5 parts Polyethylene wax 0.3 parts Magenta dye Layer ink composition 11 (comparative ) Magenta hue dye sample No. 11 6.0 parts Polyvinyl acetal 3.5 parts Solvent 90.5 parts Polyethylene wax 0.05 part Magenta dye layer ink composition 12 (comparative ) -Magenta hue dye sample No. 12 6.0 parts-Polyvinyl acetal 3.5 parts-Solvent 90.5 parts-Polyethylene wax 0.05 parts Magenta dye layer ink composition 13 (comparative )-Magenta hue dye sample No. 13 5.4 parts-Polyvinyl acetal 3.5 parts-Solvent 91.1 parts-Polyethylene wax 0.04 parts Next, an ink composition for forming the yellow dye layer 12Y and the cyan dye layer 12C was prepared with the following composition.

Yellow dye layer ink composition: Holon Brilliant Yellow 6GL 3.0 parts Macrolex Yellow 6G 0.5 parts Polyvinyl acetal 3.5 parts Solvent 93.0 parts Polyethylene wax 0.04 parts Cyan dye layer Ink composition- 2.6 parts of dye represented by the above formula [5]-0.6 parts of holon brilliant blue SR-3.2 parts of polyvinyl acetal-0.3 parts of polyvinyl butyral-93.3 parts of solvent-polyethylene Wax 0.03 parts In addition, in the above ink composition, as a polyvinyl acetal, S-LEC KS-5 manufactured by Sekisui Chemical Co., Ltd.,
As polyvinyl butyral, S-LEC BX-1 manufactured by Sekisui Chemical Co., Ltd., as a solvent, a mixed solvent of methyl ethyl ketone / toluene = 1/1 (weight ratio), and as polyethylene wax, BASF manufactured by BASF
WAX AF-31 was used respectively.

Using these ink compositions, a thickness of 6.
13 types of thermal transfer sheets having a magenta dye layer, a yellow dye layer and a cyan dye layer on a 0 μm polyethylene terephthalate base sheet so as to have a dry coating amount of 1.0 g / m ² and dried. A sample was obtained. The thermal transfer sheet sample No. Corresponds to the number of the magenta dye layer ink composition.

Next, an image receiving paper was manufactured in the following manner.

Preparation of Image Receiving Paper・ Polyester resin (Vylon 600, manufactured by Toyobo Co., Ltd.) 4.0 parts ・ Vinyl chloride-vinyl acetate copolymer (1000A, manufactured by Denki Kagaku Kogyo KK) 6.0 parts・ Amino-modified silicone oil (Shin-Etsu Chemical Co., Ltd., X-22-3050C) 0.2 parts ・ Epoxy-modified silicone oil (Shin-Etsu Chemical Co., Ltd., X-22-3000E) 0.2 parts -Methyl ethyl ketone 44.8 parts-Toluene 44.8 parts The coating liquid for forming the receptor layer is applied to one surface of synthetic paper (Yopo EPG150, manufactured by Oji Yuka Co., Ltd.) as a substrate and dried. To obtain an image receiving paper (4.5 g / m ² when dried).

On this image receiving paper, a sample printed in monochrome using only various magenta dye layers, a sample printed an image including a human face (skin color) as described later, a magenta dye layer, a cyan dye layer, A sample in which black was printed using the yellow dye layer was produced. The printing conditions were as follows: the applied energy of the thermal head was 6 to 100.
mJ / mm ² , feed rate 33.3 ms. / Line.

The following evaluation was performed on these samples. (1) The value of the saturation C ^{* and} the value of the hue angle H ° at L ^* (brightness index) = 50 Using CR-221 manufactured by Minolta (based on the 45-0 method defined in JIS Z 8722). Measure. Observation condition is light source D
₆₅ was used. (2) Skin color reproducibility Images including various human faces were printed with a video printer VY-170 manufactured by Hitachi, Ltd., and evaluated visually.

◎: The skin color is reproduced very vividly ○: The skin color is simply reproduced △: The skin color is reproduced slightly dull (3) Black density Three color dye About the sample which printed black using the layer, a densitometer (RD-918, manufactured by Macbeth)
Was used to measure the concentration. The numerical data and evaluation were as follows.

◎: Black density value of 2.5 or more…: Black density value of 2.5 to 2.35 Δ: Black density value of 2.35 to 2.2 ×: Black density value of less than 2.2 It is shown in Table 2 below.

[0052]

[Table 2]

[0053]

The effects of the present invention are clear from the above results. That is, since the magenta dye layer of the thermal transfer sheet of the present invention contains a magenta hue dye obtained by mixing a predetermined dye, skin color reproducibility (having a wide reproduction range,
And a clear color is obtained). Further, the black density in the three-color superimposed printing can be obtained in an appropriate range.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet 11 ... Base material sheet 12 ... Dye layer 12M ... Magenta dye layer 12Y ... Yellow dye layer 12C ... Cyan dye layer

Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41M 5/33-5/40 CAPLUS (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A thermal transfer sheet having a magenta dye layer on a base sheet, wherein the magenta dye layer contains a dye represented by the following formulas (1) and (2) in a weight content ratio of 10: A thermal transfer sheet comprising a magenta hue dye obtained by mixing in a range of 90 to 50:50, and polyethylene wax particles. Embedded image Embedded image 2. The magenta hue dye further contains 5 to 30 parts by weight of a dye represented by the following formula [3] based on 100 parts by weight of the dye mixture of the formulas [1] and [2]. The thermal transfer sheet according to claim 1, wherein: Embedded image