JPH03163167A - Dye and thermal transfer sheet containing same - Google Patents

Abstract

PURPOSE:To give a sharp image even by the application of thermal energy for a very short time and to impart light resistance to the formed image by using a specified dye in a thermal transfer process in which a sublimable dye is used. CONSTITUTION:The title thermal transfer sheet consists of a substrate sheet and a dye layer formed on either surface of the sheet, wherein a compound of formula I is used as the dye contained in the dye layer. This dye can easily be produced by, e.g. oxidatively coupling a phenol of formula II with an aniline of formula III in alkaline conditions in the presence of an oxidizing agent such as silver chloride, ammonium persulfate or red prussiate of potash.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a new dye and a thermal transfer sheet, and more particularly to a dye and a thermal transfer sheet that can provide recorded images with excellent clarity and various fastnesses, especially light fastness. The purpose is to provide thermal transfer sheets. (Prior Art) Various thermal transfer methods have been known in the past. Among them, a sublimable dye is used as a recording agent, and this is supported on a base sheet such as paper to form a thermal transfer sheet. The thermal transfer sheet is layered on a transferable material that can be dyed, such as polyester woven fabric, and thermal energy is applied in a pattern from the back side of the thermal transfer sheet.
Sublimation transfer methods are used to transfer sublimable dyes to the transfer material. (Problems to be Solved by the Invention) In the above-mentioned sublimation printing method, in which the material to be transferred is, for example, a polyester woven fabric, heat energy is applied for a relatively long time, so the material to be transferred is As a result of being heated by the applied thermal energy, relatively good dye migration was achieved. However, with advances in recording methods, delicate characters and figures can be printed onto these materials at high speeds using thermal heads, etc., using transfer materials such as polyester sheets or paper with a dye-receiving layer. Alternatively, when forming a photographic image, the application of thermal energy is required to be extremely short, on the order of seconds or less, and therefore, the sublimable dye and the transfer material cannot be sufficiently heated in such a short time. Therefore, it is not possible to form an image with sufficient density.

Therefore, in order to cope with such high-speed recording, sublimable dyes with excellent sublimation properties were developed, but dyes with excellent sublimation properties generally have a small molecular weight, so the light fastness of the formed image is poor. inferior, and there are problems with long-term storage.

In order to avoid such problems, if a sublimable dye with a relatively large molecular weight is used, the sublimation speed will be inferior in the high-speed recording method described above, so it will not be possible to form an image with satisfactory clarity and density as described above. I don't get it.

Therefore, an object of the present invention is to provide a clear image with sufficient density even by applying heat energy for an extremely short time as described above in a thermal transfer method using a sublimable dye, and to provide an excellent image. It is an object of the present invention to provide dyes and thermal transfer sheets that exhibit various fastness properties, particularly light fastness. (Means for solving the problems) The above object is achieved by the present invention as described below.

That is, the present invention comprises a dye represented by the following formula (I), a base sheet, and a dye layer formed on one side of the base sheet, and the dye included in the dye layer is represented by the following formula. (I)
This is a thermal transfer sheet characterized by a dye represented by (Function) The dye represented by the following general formula (A) is disclosed in European Patent No. 147.
No. 747, dyes of formula (I) are not described in that specification or in other known documents.

The dyes of the general formula (A) (excluding formula I) exhibit a clear cyan color tone and excellent heat transferability as dyes for thermal transfer sheets, and form high-density and clear images, but they do not affect the transfer material after transfer. The light resistance of the dye in the image-receiving layer is low, and the image quality deteriorates during long-term storage. On the other hand, although the dye of formula (I) has a similar structure, it exhibits a clear cyan color tone and excellent heat transferability as a dye for thermal transfer sheets, and forms images with excellent light resistance.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The dye of the present invention can be produced by a method known per se. For example, a phenol of the following formula A and an aniline of the following formula B are oxidized in an alkaline manner in the presence of an oxidizing agent such as silver chloride, ammonium persulfate, red blood salt, etc. It can be easily manufactured by ringing. The above dye has a melting point of 132.2-132.5°C, 65
Maximum absorption wavelength of 5 nm (in ethyl acetate). l. 45X1
It has a molar extinction coefficient of 0' and a molecular weight of 435.99.

The thermal transfer sheet of the present invention is characterized by using the above-mentioned specific dye, and other than that, the structure may be the same as that of conventionally known thermal transfer sheets.

The base material sheet used in the thermal transfer sheet of the present invention containing the above-mentioned dye may be any conventionally known material having a certain degree of heat resistance and strength.
．． Paper, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, aramid film, polyvinyl alcohol film, cellophane, etc. with a thickness of about 5 to 50 tLm, preferably 3 to 1000Lm, Particularly preferred is polyester film. The dye layer provided on the surface of the base sheet as described above is a layer in which the dye is supported by an arbitrary binder resin. As the binder resin for supporting the dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxybrobyl cellulose, methyl cellulose, cellulose acetate, and vinegar. Cellulose resins such as cellulose oxate; vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl pyrrolidone, and polyacrylamide; among these, polyvinyl butyral and polyvinyl acetate are particularly preferred. Cool is preferable from the viewpoint of heat resistance, dye transferability, etc.

The dye layer of the thermal transfer sheet of the present invention is basically formed from the above-mentioned materials, but may also contain various conventionally known additives as required. Preferably, such a dye layer is prepared by adding the dye, binder resin, and other optional components in a suitable solvent, dissolving or dispersing each component, and preparing a coating liquid or ink for forming the dye layer. It is formed by coating and drying it on a base sheet.

The dye layer formed in this way has a dye layer of 0.2 to 5. 0 μm,
The thickness is preferably about 0.4 to 2.0 μm, and
Said dyes in the dye layer are suitably present in an amount of 5 to 70% by weight, preferably 10 to 60% by weight of the weight of the dye layer.

The thermal transfer sheet of the present invention as described above is sufficiently useful for thermal transfer as it is, but an anti-adhesive layer, that is, a release layer may be further provided on the surface of the dye layer, and such a layer may be provided. By doing so, it is possible to prevent adhesion between the thermal transfer sheet and the transfer material during thermal transfer, use a higher thermal transfer temperature, and form an image with even better density.

As this mold release layer, even if an inorganic powder with anti-adhesive properties is simply attached, it has a considerable effect, and in addition, resins with excellent mold release properties such as silicone polymers, acrylic polymers, and fluorinated polymers can be used. It can be formed by providing a release layer of 0.01 to 5 μm, preferably 0.05 to 2 μm.

Incidentally, the above-mentioned inorganic powders or mold-releasing polymers exhibit sufficient effects even when incorporated into the dye layer. Furthermore, a heat-resistant layer may be provided on the back side of such a thermal transfer sheet in order to prevent the adverse effects of the heat of the thermal head. The transfer material used to form an image using the thermal transfer sheet as described above may be any material as long as its recording surface has dye receptivity to the above-mentioned dyes. In the case of paper, metal, glass, synthetic resin, etc. that do not have any properties, a dye-receiving layer may be formed on at least one surface thereof. As the means for applying thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the recording material as described above, any conventionally known applying means can be used.
For example, by controlling the recording time using a recording device such as a thermal printer (for example, Video Printer VY-100 manufactured by Hitachi),
The intended purpose can be fully achieved by applying thermal energy of about 1/m. (Example) Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified. Example 1 A dye layer type ink composition having the following composition was prepared, and it was coated and dried on a 6 μm thick polyethylene terephthalate film whose back surface had been heat-resistant treated so that the dry coating amount was 1.0 g/rrf. A thermal transfer sheet of the present invention was obtained. Dye of formula (1) 3.0 parts Polyvinyl butyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene
46.25 parts Comparative Examples 1 to 3 Thermal transfer sheets of comparative examples were obtained in the same manner as in Example 1 except that the following dyes were used as the dyes in Example 2. Next, synthetic paper (Oji Yuka Co., Ltd., Yubo FP) was used as a base sheet.
G#150), apply a coating liquid with the following composition on one side at a rate of 10.0g/rrf when dry,
A transfer material was obtained by drying at 00°C for 30 minutes. Polyester resin (Vylon200, manufactured by Toyobo) 11
．． 5 parts vinyl chloride/vinyl acetate copolymer (VY}I}l, UC
C) 5.0 parts Amino-modified silicone (KF-393, manufactured by Shin-Etsu Chemical) 1.2 parts Eboxy-modified silicone (X-22-343, manufactured by Shin-Etsu Chemical) 1.2
Methyl ethyl ketone/toluene/cyclohexanone (
Weight ratio 4:4:2) 1 02. 0 copies The thermal transfer sheet of the present invention and the transfer material described above were placed one on top of the other with their respective dye layers and dye-receiving surfaces facing each other, and a head voltage of 10 V was applied from the back side of the thermal transfer sheet for a printing time of 8.
0 msec. Recording was performed with a thermal head under the following conditions, and the results shown in Table 1 below were obtained.

11''-11 Storage stability: Recorded images were left in an atmosphere at 50°C for a long period of time and evaluated. 0: The sharpness of the image does not change, and the white paper does not become colored even when the surface is rubbed with white paper. ○: Sharpness is slightly lost and the white paper is slightly colored.

△: Sharpness was lost and the white paper became colored. ×: The image became unclear and the white paper was significantly colored. Color development: Densitometer RD-9 manufactured by Macbeth, USA
The value measured in 18 was used as the standard. 0: 2.50 or more ○: 2.10 or more and less than 2.50 Δ: 1.70 or more 2. IO less than X: l. Light resistance of less than 70: A 10-hour light resistance test was conducted based on JIS L 0842, and the rate of discoloration from the initial density was defined as the light resistance.

o: less than 4% ○: 4% or more but less than 8% Δ: 8% or more and less than l2% ×: 12% or more comprehensive evaluation: 0: Fully satisfies various fastness requirements for images.

○: Some of the fastness is inferior, but it can withstand use. Ru. Δ: The image had insufficient fastness properties.

×: Unusable as an image. (Effects) According to the present invention as described above, the dye of formula (I) exhibits a clear cyan color tone and excellent heat transferability as a dye for thermal transfer sheets, and produces images with excellent fastness, especially light fastness. Form.

Claims (2)

[Claims] (1) A dye represented by the following formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (2) It consists of a base sheet and a dye layer formed on one side of the base sheet, and the dye included in the dye layer is a dye represented by the following formula (I). Heat transfer sheet. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I)