JPH0699676A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To improve preserving properties, the color density, sharpness and light fastness of recorded image by a method wherein cyan dye in dye carrying layer is prepared by mixing one or more kinds of dye represented by specified general formulae with dye represented by other specified general formula. CONSTITUTION:The heat transfer sheet concerned consists of base material sheet and cyan dye, which is prepared by mixing one or more kinds of dye represented by formulae I-III with dye represented by formula IV, in dye carrying layer formed on one side of the sheet. In this case, R1 and R2 represent substitutable alkyl group, cycloalkyl group, aryl group, allyl group, vinyl group, aralkyl group or peterocyclic group, R3 represents hydrogen atom, halogen atom, cyano group and substitutable alkyl group, alkoxy group or-NHR5 and R5 represents alkylcarbonyl group, aryl carbonly group, alkyl sulfonyl group or aryl sulfonyl group. By employing the mixture of the specified dyes, fully colored image excellent in color density, sharpness and light fastness is given even when heat energy is given for a short period of time and further the resultant image also has excellent preserving properties.

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 which is excellent in storability of the thermal transfer sheet itself and excellent in color density, sharpness and light resistance of recorded images.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods have been known. Among them, dyes that sublime, vaporize, liquefy or diffuse by heat (hereinafter simply referred to as dyes) are used as recording agents, and these are used as a base material such as paper. The sheet is carried as a thermal transfer sheet, and it is transferred to a transferable material that can be dyed with a dye, for example, a polyester woven cloth, and thermal energy is applied in a pattern from the back surface of the thermal transfer sheet to transfer the dye to the transferable material A sublimation transfer method is used. Recently, there has been proposed a method of forming various full-color images on paper or plastic film by using the sublimation type thermal transfer system. In this case, the thermal head of the printer is used as the heating means, and a large number of three-color or four-color dots are transferred to the transfer material by heating for an extremely short time, and the full-color image of the original is formed by the multi-color dots. To reproduce. The image formed in this way is extremely clear because the coloring material used is a dye and has excellent transparency, so the resulting image has excellent reproducibility and gradation of intermediate colors, and It is possible to form a high quality image which is similar to the image by offset printing or gravure printing and which is comparable to a full color photographic image.

[0003]

[Problems to be solved by the invention] However,
The most important problems in the above thermal transfer method are the color density and light resistance of the formed image. That is, in the case of high-speed recording, the application of thermal energy is required to be performed in an extremely short time of seconds or less. Therefore, in such a short time, the dye and the transfer material are not sufficiently heated. It is not possible to form an image with high density. Therefore, an indoaniline type dye represented by the following formula A is a dye corresponding to such high speed recording as disclosed in US Pat.
No. 0,870. However,
The thermal transfer sheet using the dye of the following formula A tends to deposit the dye on the thermal transfer sheet with the passage of time, and when an image is formed using such a thermal transfer sheet on which the dye is deposited,
This causes a problem that the resolution of the obtained image is significantly reduced. Therefore, an object of the present invention is to provide a sufficiently dense and clear image in a thermal transfer method using a dye, and the formed image shows excellent fastness, particularly excellent light resistance, and a thermal transfer sheet. It is an object of the present invention to provide a thermal transfer sheet which is excellent in its storage stability.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention comprises a base material sheet and a dye carrying layer formed on one surface of the base material sheet, and the cyan dye contained in the dye carrying layer is represented by the following formula 1
~ A thermal transfer sheet comprising a mixture of at least one dye represented by Formula 3 and a dye represented by Formula A below.

[Chemical 2] (In the formula, R ₁ , R ₂ and R ₄ are an optionally substituted alkyl group, cycloalkyl group, aryl group, allyl group,
It represents a vinyl group, an aralkyl group or a heterocyclic group, and R ₃ is
Represents a hydrogen atom, a halogen atom, a cyano group, an optionally substituted alkyl group, an alkoxy group or -NHR ₅ ,
R ₅ is an alkylcarbonyl group, an arylcarbonyl group,
It represents an alkylsulfonyl group or an arylsulfonyl group. )

[0005]

[Function] By mixing and using a specific dye,
Even when heat energy is applied for an extremely short time, it is possible to provide a thermal transfer sheet which provides a full-color image excellent in color density, sharpness and light resistance and also has excellent storage stability of the thermal transfer sheet itself.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. Formula 1 used in the present invention
~ The dyes represented by formula 3 can be used alone or as a mixture. The dyes of formulas 1 to 3 suitable for use in the present invention are listed below in Tables 1 to 3 as represented by their substituents.

[0007]

Table 1 Dyes of formula 1

[0008]

[Table 2] Dye of formula 2

Table 3 Dyes of formula 3

The dyes of the above formulas 1 to 3 and the dyes of the formula A are generally used in a weight ratio of 1 to 90:99 to 10, though they differ depending on the particular dyes selected. It is preferable. If the proportion of the dyes of the formulas 1 to 3 is too large, the light resistance is deteriorated, and on the other hand, if the ratio is too small, the preservability of the thermal transfer sheet itself is deteriorated.

The thermal transfer sheet of the present invention is characterized by using the specific dye mixture as described above, and other configurations may be the same as those of the conventionally known thermal transfer sheet. The base sheet used in the thermal transfer sheet of the present invention using the above dye mixture may be any one as long as it has conventionally known heat resistance and strength to some extent, for example, 0.5 to 50 μm, Paper having a thickness of about 3 to 10 μm, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, aramid film, polyvinyl alcohol film, cellophane and the like are preferable, and polyester film is particularly preferable. is there.

The dye carrying layer provided on the surface of the substrate sheet as described above is a layer in which the dye mixture is carried by any binder resin. As the binder resin for supporting the above-mentioned dye mixture, any conventionally known binder resin can be used, and preferable examples are ethyl cellulose,
Cellulose resins such as hydroxyethyl cellulose, ethyl hydroxycellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinyl alcohol, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, polyvinyl aceto Examples of the acetal, polyvinylpyrrolidone, polyacrylamide, vinyl resins such as polystyrene, and the like, among them, polyvinyl butyral and polyvinyl acetal are particularly preferable in terms of heat resistance, dye transferability, and the like,
Ethyl cellulose and ethyl hydroxyethyl cellulose are preferable in terms of sensitivity.

The dye-carrying layer of the thermal transfer sheet of the present invention is basically formed of the above-mentioned materials, but may also contain various additives similar to the conventionally known ones, if necessary. Such a dye-supporting layer is preferably prepared by adding the above-mentioned dye mixture, a binder resin and other optional components in a suitable solvent to dissolve or disperse each component to prepare a coating liquid or an ink for forming a support layer. Is applied and dried on the above-mentioned substrate sheet to form. The supporting layer thus formed has a thickness of 0.2 to 5.0 μm, preferably 0.4 to 2.0 μm.
It has a thickness of about m, and the dye mixture in the carrier layer is 5 to 90% by weight, preferably 20 to 70% by weight of the carrier layer.
It is preferably present in an amount of% by weight. The thermal transfer sheet of the present invention as described above is sufficiently useful for thermal transfer up to that point, but an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye-carrying layer, and such a layer is provided. As a result, it is possible to prevent the thermal transfer sheet from sticking to the material to be transferred during thermal transfer, use a higher thermal transfer temperature, and form an image of even higher density.

As the release layer, even if only the inorganic powder having anti-adhesive property is adhered, a considerable effect is exhibited.
For example, from a resin having excellent releasability such as a silicone polymer, an acrylic polymer, or a fluorinated polymer, 0.01 to
It can be formed by providing a release layer having a thickness of 5 μm, preferably 0.05 to 2 μm. Incidentally, the inorganic powder or the releasing polymer as described above has a sufficient effect even when incorporated in the dye carrying 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 material to be transferred used for forming 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 dye, and 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. By controlling the recording time with a recording device such as a printer (for example, a video printer VY-100 manufactured by Hitachi, Ltd.), thermal energy of about 5 to 100 mJ / mm ² is applied to sufficiently achieve the intended purpose. Can be achieved. In particular, the thermal transfer sheet of the present invention can form a cyan image and is used in combination with a yellow and magenta thermal transfer sheet, or color reproduction is performed by a thermal transfer sheet in which yellow, cyan and magenta dye layers are provided in a surface sequential manner. It is possible to provide a full-color image having excellent properties.

[0015]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Examples 1 to 15 Ink compositions for forming a dye carrying layer having the following compositions were prepared and applied onto a 6 μm-thick polyethylene terephthalate film having a heat-treated back surface so that the dry coating amount was 1.0 g / m ^2. And it dried and the thermal transfer sheet of this invention was obtained. Ink composition Dyes of Formulas 1 to 3 Part a Dye of Formula A Part b Resin of Table 4 below 4 parts Methyl ethyl ketone (96-ab) x 0.5 parts Toluene (96-ab) x 0.5 parts However, when the dye is insoluble in the above composition, DMF, dioxane, chloroform or the like was appropriately used as a solvent (the dyes used and their mixing ratios (a, b) are shown in Table 5 below).
See).

[0016]

[Table 4]

Next, a synthetic paper (Yupo FPG # 150, manufactured by Oji Yuka) was used as the base sheet, and a coating solution having the following composition was applied to one surface of the paper at a rate of 10.0 g / m ² when dried. And then dried at 100 ° C. for 30 minutes to obtain a transfer material. Polyester resin (Vylon200, Toyobo) 11.5 parts Vinyl chloride / vinyl acetate copolymer (VYHH, UCC) 5.0 parts Amino-modified silicone (KF-393, Shin-Etsu Chemical Co., Ltd.) 1.2 parts Epoxy-modified Silly Corn (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

Thermal transfer recording test The thermal transfer sheet of the present invention and the material to be transferred are superposed with the dye carrying layer and the dye receiving surface facing each other, from the back surface of the thermal transfer sheet, head applied voltage 11V, printing time 1
6 msec. Recording was carried out with a thermal head under the conditions described above, and the results shown in Table 5 below were obtained. Light fastness test the light resistance test of the obtained cyan image thermal transfer test xenon fade meta (manufactured by Atlas, Ci35
Conducted in A) (black panel temperature 50 ° C., 50 kLu
x), but none of them did not discolor after irradiation for 50 hours. Measurement of color density It was measured with a densitometer RD-918 manufactured by Macbeth Co., USA. Storage Test of Thermal Transfer Sheet The thermal transfer sheet of the present invention was stored at 60 ° C. for 60 hours, and the deposition of dye was visually determined according to the following criteria, and the results shown in Table 5 below were obtained. ○: No precipitation of dye is observed. △: Precipitation of dye is partially observed. ×: A large amount of dye is observed to be deposited.

[0019]

[Table 5]

Comparative Examples 1 to 12 The following dyes were used in place of the dyes used in Examples, and the same results as shown in Table 6 were obtained in the same manner as in Example 1. Dye of Formula 1 to Formula 3 or Formula A Part a Resin in Table 4 4 parts Methyl ethyl ketone (96-a) x 0.5 parts Toluene (96-a) x 0.5 parts

[0021]

[Table 6]

[0022]

[Effects] According to the present invention as described above, by mixing and using a specific dye, a full-color image excellent in color density, sharpness and light fastness can be obtained even when heat energy is applied for an extremely short time. It is possible to provide a thermal transfer sheet which is excellent in storage stability of the thermal transfer sheet itself.

Claims (1)

[Claims] 1. A base sheet and one surface of the base sheet
And a dye-carrying layer formed on the
The cyan dye is a dye represented by the following formulas 1 to 3.
A mixture of at least one kind and a dye represented by the following formula A:
A thermal transfer sheet characterized in that [Chemical 1](R in the formula₁, R_TwoAnd R_FourIs an optionally substituted
Alkyl group, cycloalkyl group, aryl group, allyl group,
Represents a vinyl group, an aralkyl group or a heterocyclic group, R _ThreeIs
Hydrogen atom, halogen atom, cyano group, even if substituted
Good alkyl group, alkoxy group or -NHR₅Represents
R₅Is an alkylcarbonyl group, an arylcarbonyl group,
Represents an alkylsulfonyl group or an arylsulfonyl group
You )