JP2572025B2 - Dye and thermal transfer sheet containing the dye - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel dye and a thermal transfer sheet, and more particularly, to a dye capable of providing a recorded image having excellent sharpness and various fastnesses, particularly excellent light fastness. The purpose is to provide a thermal transfer sheet.

(Prior Art) Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and this is carried on a base sheet such as paper to form a thermal transfer sheet, which is then dyed with a sublimable dye. A sublimation transfer method has been performed in which a sublimable dye is transferred to a transfer-receiving material by applying thermal energy in a pattern form from the back surface of a thermal transfer sheet to a transferable material such as a polyester woven cloth.

(Problems to be Solved by the Invention) In the above-described sublimation transfer method, in the sublimation printing method in which the material to be transferred is, for example, a woven fabric made of polyester or the like, since the application of thermal energy is relatively long, the material to be transferred is As a result, relatively good dye transfer is achieved as a result of heating with the applied thermal energy.

However, due to advances in recording methods, using a thermal head or the like at a high speed, for example, using a transfer material provided with a dye receiving layer on a polyester sheet or paper, and delicate characters and figures on these transfer materials Alternatively, in the case of forming a photographic image, the application of heat energy is required to be performed in a very short time of less than seconds, and therefore, in such a short time, the sublimable dye and the material to be transferred are not sufficiently heated. For
An image with a sufficient density cannot be formed.

Therefore, to cope with such high-speed recording, sublimable dyes with excellent sublimability have been developed.However, dyes with excellent sublimability generally have a light resistance of the formed image due to its small molecular weight. Poor and has problems with long-term storage.

In order to avoid such a problem, when a sublimable dye having a relatively large molecular weight is used, the sublimation speed is inferior in the high-speed recording method as described above, so that an image having satisfactory sharpness and density is formed as described above. I can't get it.

Therefore, an object of the present invention is to provide a clear image having a sufficient density even by applying thermal energy for a very short time as described above in a thermal transfer method using a sublimable dye, and the formed image is excellent. Another object of the present invention is to provide a dye and a thermal transfer sheet exhibiting various fastnesses, especially light fastness.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention comprises a dye for a thermal transfer sheet represented by the following formula (I), a base sheet and a dye layer formed on one surface of the base sheet, and a dye included in the dye layer. Is a dye represented by the following formula (I):

(Action) The dye represented by the following general formula (A) is described in European Patent No. 1477.
No. 47, the dyes of the formula (I) are not described in the above-mentioned specification nor in other known documents.

The dye of formula (A) (except formula I) exhibits a clear cyan color tone and excellent heat transferability as a dye for a thermal transfer sheet and forms a high-density and clear image. In the image receiving layer, the light resistance of the dye is low and the image quality is deteriorated during long-term storage.

On the other hand, the dye of the formula (I), despite having a similar structure, exhibits a clear cyan color tone and excellent heat transfer property as a dye for a thermal transfer sheet, and forms an image having excellent light fastness.

Preferred Embodiment Next, the present invention will be described in more detail with reference to preferred embodiments.

The dyes of the present invention can be produced by a known production method, for example, by converting a phenol represented by the following formula A and an aniline represented by the following formula B in the presence of an oxidizing agent such as silver chloride, ammonium persulfate, or red blood salt.
It can be easily produced by oxidative coupling under alkaline conditions.

The above dye has a melting point of 132.2-132.5 ° C., a maximum absorption wavelength of 655 nm (in ethyl acetate), a molar extinction coefficient of 1.45 × 10 ⁴ and a molecular weight of 435.99.

The thermal transfer sheet of the present invention is characterized by using the above-mentioned specific dye as described above, and the other configuration may be the same as the configuration of a conventionally known thermal transfer sheet.

As the base sheet used in the thermal transfer sheet of the present invention containing the dye, any substrate may be used as long as it has a conventionally known degree of heat resistance and strength, for example,
Paper having a thickness of about 0.5 to 50 μm, preferably about 3 to 10 μm;
Examples include various processed papers, polyester films, polystyrene films, polypropylene films, polysulfone films, polycarbonate films, aramid films, polyvinyl alcohol films, cellophane, and the like, with polyester films being particularly preferred.

The dye layer provided on the surface of the base sheet as described above is a layer in which the dye is carried by an arbitrary binder resin.

As a binder resin for supporting the dye,
Any of the conventionally known ones can be used, and preferred examples thereof include ethylcellulose, hydroxyethylcellulose, ethylhydroxycellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, cellulose resins such as cellulose acetate butyrate, polyvinyl alcohol, and polyvinyl acetate. And vinyl-based resins such as polyvinyl butyral, polyvinyl acetoacetal, polyvinyl pyrrolidone, and polyacrylamide. Of these, polyvinyl butyral and polyvinyl acetal are particularly preferable in terms of heat resistance, dye transferability, and the like. .

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 additives as conventionally known, if necessary.

Such a dye layer is preferably prepared by adding the above-mentioned dye, a binder resin and other optional components in an appropriate solvent and dissolving or dispersing each component to prepare a coating liquid or ink for forming a dye layer. It is formed by applying and drying on a base material sheet.

The dye layer thus formed has a thickness of about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the dye in the dye layer accounts for 5 to 70% by weight of the weight of the dye layer, preferably Is
Suitably it is present in an amount of from 10 to 60% by weight.

Although the thermal transfer sheet of the present invention as described above is sufficiently useful for thermal transfer as it is, an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye layer, by providing such a layer. , To prevent sticking of thermal transfer sheet and transfer material at the time of thermal transfer, use higher thermal transfer temperature,
An image having an even higher density can be formed.

As this release layer, even if only an anti-adhesive inorganic powder is simply attached, a considerable effect is exhibited.Moreover, for example, a silicone polymer, an acrylic polymer, a resin having excellent release properties such as a fluorinated polymer is 0.01% or less. It can be formed by providing a release layer having a thickness of 5 to 5 μm, preferably 0.05 to 2 μm.

The inorganic powder or the releasable polymer as described above has a sufficient effect even if it is included 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 prevent adverse effects due to 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 a dye-accepting property for the dye. In the case of paper, metal, glass, synthetic resin or the like having no property, 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, a thermal printer (for example, By controlling the recording time with a recording device such as a video printer VY-100 manufactured by Hitachi, Ltd., 5 to 100 m
By applying thermal energy of about J / mm ² , the intended purpose can be sufficiently achieved.

(Examples) Next, the present invention will be more specifically described with reference to Examples and Comparative Examples. In the following description, parts and% are based on weight unless otherwise specified.

Example 1 An ink composition for forming a dye layer having the following composition was prepared, and applied to a 6 μm-thick polyethylene terephthalate film having a heat-treated rear surface so as to have a dry coating amount of 1.0 g / m ² and dried. The thermal transfer sheet of the present invention was obtained.

Dye of formula (I) 3.0 parts Polyvinyl butyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts Comparative examples 1 to 3 The following dyes were used as the dyes in Example 2 and the others were the same as in Example 1 except for thermal transfer. I got a sheet.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Next, the base sheet and synthetic paper (Oji Yuka, YUPO FPG # 1
Using 50), a coating liquid having the following composition was applied on one surface of the coating at a rate of 10.0 g / m ² when dried, and dried at 100 ° C. for 30 minutes to obtain a transfer-receiving material.

Polyester resin (Vylon200, manufactured by Toyobo) 11.5 parts Vinyl chloride / vinyl acetate copolymer (VYHH, manufactured by UCC) 5.0 parts Amino-modified silicone (KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2
Part Epoxy-modified silicone (X-22-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methyl ethyl ketone / toluene / cyclohexanone (weight ratio 4: 4: 2) 102.0 parts Each of the above-mentioned thermal transfer sheet of the present invention and the above-mentioned material to be transferred. The dye layer and the dye receiving surface are superposed on each other, and the voltage applied to the head from the back of the thermal transfer sheet is 10 V and the printing time is 8.0 ms.
Recording was performed with a thermal head under the conditions of ec. and the results shown in Table 1 below were obtained.

Storage property: The recorded image was left standing in an atmosphere of 50 ° C. for a long time to evaluate.

A: The sharpness of the image does not change, and the white paper is not colored even if the surface is rubbed with white paper.

：: The sharpness is slightly lost and the white paper is slightly colored.

Δ: Sharpness was lost and white paper was colored.

X: The image was unclear and the white paper was markedly colored.

Chromogenicity: Densitometer RD-918 manufactured by Macbeth USA
The value measured in was used as a reference.

:: 2.50 or more ○: 2.10 or more and less than 2.50 △: 1.70 or more and less than 2.10 ×: less than 1.70 Light fastness: A light fastness test was performed for 10 hours based on JIS L0842, and the rate of fading from the initial concentration was taken as light fastness.

◎: Less than 4% ○: 4% or more and less than 8% △: 8% or more and less than 12% ×: 12% or more Overall rating: ：: Sufficiently satisfies various fastnesses required for images.

：: Some inferior in robustness but endured use.

Δ: Image with insufficient fastness.

×: The image cannot be used.

(Effects) According to the present invention as described above, the dye of the formula (I) exhibits a clear shear tone and excellent heat transferability as a dye for a thermal transfer sheet, and forms an image having excellent fastness properties and excellent light fastness. I do.

Claims (2)

(57) [Claims] 1. A dye for a thermal transfer sheet represented by the following formula (I). 2. A dye comprising a base sheet and a dye layer formed on one surface of the base sheet, wherein the dye contained in the dye layer is a dye represented by the following formula (I). Thermal transfer sheet.