JPH10157314A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve color reproducibility, sensitivity, coloring density, and fastness of a formed image, particularly of cyan color by using a mixture of a C.I. disperse blue 24 and a dye to be expressed by a specified formula for a dye, in a thermal transfer sheet having a thermal transfer layer arranged on a base material sheet. SOLUTION: A thermal transfer sheet, which performs heat printing corresponding to image information by a thermal head and the like so as to provide an image on a material to be transferred, comprises a thermal transfer layer formed of a binder resin and a dye arranged on a base material sheet. In this case, a mixture of a C.I. disperse blue 24 and a dye to be expressed by a separately described general formula is used for the dye. In the formula, X represents a hydrogen atom, an alkyl group, a formyl amino group, an alkylcarbonyl amino group, a benzoyl amino group, a halogen atom, Y represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, R, R<1> , R<2> represent an alkyl group and an allyl group. The thermal transfer layer may contain an silicone oil or a silicone resin.

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 that is particularly suitable for obtaining an image on an object by performing heating printing according to image information using a thermal head or a laser. .

[0002]

2. Description of the Related Art In recent years, as a method of outputting an image on a CRT display as a hard copy, a thermal transfer sheet is heated by a thermal head or the like whose heat is controlled by an electric signal, and a sublimation dye in a color material layer of the thermal transfer sheet is removed. 2. Description of the Related Art A thermal transfer method of forming an image by transferring an image to a heat transfer sheet is widely used. This method uses yellow, magenta,
By overprinting the three primary colors of cyan, a full-color image can be formed. As the thermal transfer sheet used in the thermal transfer system, a sheet obtained by applying a binder resin containing a sublimable dye to a base material to form a color material layer is generally used.

Important problems in the thermal transfer system include color reproducibility, sensitivity, color density, and fastness (heat transfer resistance, light resistance) of a formed image. That is, the thermal transfer sheet is required to have faithful color reproducibility with respect to the original image, sufficient color developability with low-energy heat, high color density, and high robustness of the obtained image. However, the conventional thermal transfer sheet was insufficient to satisfy all of these properties.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a thermal transfer sheet which solves the above-mentioned problems, especially for cyan. The purpose is to provide.

[0005]

Means provided by the present invention to solve the above-mentioned problems are as follows. First, as described in claim 1, a resin is transferred onto a base sheet by a binder resin and heating. In a thermal transfer sheet provided with a thermal transfer layer made of a dye to be transferred onto an object to be transferred, the dye is C.I. I.
A thermal transfer sheet comprising a mixture of Disperse Blue 24 and a dye represented by the following general formula [1].

[0006]

Embedded image

(Wherein, X represents any one of a hydrogen atom, an alkyl group, a formylamino group, an alkylcarbonylamino group, a benzoylamino group, an alkoxycarbonylamino group and a halogen atom, and Y represents a hydrogen atom, an alkyl group , An alkoxy group or a halogen atom, and R, R ¹ and R ² each represent an alkyl group or an allyl group.)

More preferably, as described in claim 2, based on the thermal transfer sheet according to claim 1, the dye in the thermal transfer layer is C.I. I. Disperse Blue 2
4 and C.I. I. It is a mixture of Solvent Yellow 93 and a dye represented by the general formula [1].

More preferably, as set forth in claim 3, based on the thermal transfer sheet according to any one of claims 1 and 2, the thermal transfer layer further contains at least either silicone oil or silicone resin. It is characterized by having.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. As shown in FIG. 1, the thermal transfer sheet (1) of the present invention has a thermal transfer layer (3) provided on a base sheet (2). Examples of the material of the base sheet (2) include paper such as condenser paper or a polyester film, a polystyrene film, a polypropylene film, and cellophane. A polyester film is particularly preferable. The thickness of the base sheet (2) is 2 to 50 μm, more preferably 2 to 16 μm. The thermal transfer layer (3) is composed of a binder resin containing a dye which is transferred by heating and transferred to a transfer target.

In the present invention, the dye contained in the thermal transfer layer (3) is C.I. I. A mixture of Disperse Blue 24 and a dye represented by the general formula [1]; I.
Disperse Blue 24 and C.I. I. A mixture of Solvent Yellow 93 and the dye represented by the general formula [1] is used.

When the cyan thermal transfer layer of the present invention is used for full-color image formation, the yellow dye used in the yellow thermal transfer layer used in combination with the cyan thermal transfer layer includes C.I. I. Disperse Yellow 2
01, or C.I. I. Disperse Yellow 231 and the like can be used.

When the cyan heat transfer layer of the present invention is used for forming a full-color image, the magenta dye used in the magenta heat transfer layer used in combination with the cyan heat transfer layer includes C.I. I. Disperse Red 6
0, C.I. I. Disperse Violet 26, C.I. I.
Solvent Red 27 or C.I. I. Solvent Red 19 or the like can be used.

The thermal transfer sheet of the present invention can be used not only for a single color of cyan, but also for the thermal energy applied when a full-color image is formed by using a combination of a yellow and magenta thermal transfer sheet with the cyan thermal transfer sheet. According to the present invention, it is possible to form a color with a suitable density and excellent color reproducibility. Further, in the case of forming a full-color image, it is possible to reproduce a wide range of colors having the best intermediate colors. Further, it is also preferable that yellow, magenta, and cyan are separately applied to one thermal transfer sheet for use.

As the binder resin contained in the thermal transfer layer (3), cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, butyral resin, acetal resin, phenoxy resin, polycarbonate Resins, polyester resins and the like can be mentioned, and phenoxy resins or mixtures of phenoxy resins and butyral resins are particularly preferred from the viewpoint of heat resistance, dye migration and the like. The glass transition point (hereinafter, simply referred to as Tg) of the binder resin is as follows:
If the Tg is lower than 50 ° C., if the Tg is lower than 50 ° C., the thermal transfer layer (3) tends to fuse to the surface of the transfer-receiving body during the sublimation transfer, or a problem occurs in the storage stability of the thermal transfer ribbon. Not preferred. The ratio of the dye and the binder resin in the thermal transfer layer (3) is as follows: dye / resin = 10/10
The ratio is preferably 0 to 300/100, more preferably 30/100 to 200/100.

In the case of sublimation transfer onto the surface of the transfer-receiving material having dye receptivity, the thermal transfer layer (3) should be provided in the heat transfer layer (3) in order to prevent the thermal fusion between the heat transfer layer (3) and the transfer-receiving surface. It is desirable to add a release agent. As the release agent to be added, a silicon-based release agent is preferable, and silicon oil and a silicone resin can be used.
A silicon-modified resin in which silicon is modified in the main chain is desirable.

When such a silicon-modified resin is added as a release agent to a sublimation transfer ink to form a film, the silicon portion, which is a release component of the silicon-modified resin, has a low compatibility with the sublimation transfer ink. Bleed on the surface. Also,
Since the main chain has high compatibility with the ink for sublimation transfer, it is integrated. As a result, the surface of the thermal transfer layer (3) is rich in the silicon portion, which is a release component, so that it is possible to have a good release property when heated. Further, since the silicon portion is bonded to the main chain, the silicon portion does not separate from the thermal transfer layer (3) due to the compatibility between the main chain and the ink for sublimation transfer, and the storage stability is excellent. .

The main chain used for such a release agent includes an acrylic resin, a cellulose resin, a vinyl resin, a polyester resin, a polyamide resin, and the like. From the viewpoint of compatibility, acrylic resins and polyester resins are desirable. The addition amount of the release agent is preferably about 0.1% to 10% based on the solid content of the ink for sublimation transfer. If the amount of the release agent is less than 0.1%, the effect of preventing fusion during heating is poor, and if it is 10% or more, the film strength of the thermal transfer layer (3) is reduced, or it is used for sublimation transfer. Since the binder resin in the ink cannot fully support the main chain of the release agent, there is a problem in the storage stability and the like of the thermal transfer ribbon, which is not preferable.

The thermal transfer layer (3) is preferably prepared by adding the above-mentioned dye, binder resin and other additives to an appropriate solvent and dissolving or dispersing the respective components to prepare an ink for the thermal transfer layer. It is formed by coating and drying on a material sheet. The dye-carrying layer thus formed has a thickness of 0.2 to
The thickness is about 5 μm, preferably about 0.4 to 3 μm.

In order to prevent the thermal head or the like from adhering to the heat-resistant base material (1) during printing of the thermal transfer ribbon with the thermal head or the like and hindering the smooth running of the thermal transfer ribbon, the heat-resistant base material ( It is desirable to provide a back coat layer (4) on the side where the thermal transfer layer (3) of 1) is not applied. Examples of the material used for the back coat layer (4) include nitrocellulose, polyester resin, acrylic resin, vinyl resin, and the like containing silicon oil, or silicon-modified material. Further, a crosslinking agent may be used in combination for the purpose of improving heat resistance. The coating thickness when providing the back coat layer (4) is preferably about 0.1 to 4 μm.

The object to be used for forming an image using the thermal transfer sheet as described above may be any object as long as its recording surface has a dye receptive property to the above-mentioned dye. In the case of paper, metal, glass, synthetic resin or the like having no dye receptivity, a dye receiving layer may be formed on at least one of the surfaces.

Examples of the resin having dye receptivity include polyolefin resins such as polyethylene and polypropylene, acetal resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, polyester resins, polystyrene resins, olefins and other resins. Examples thereof include a copolymer resin with a vinyl monomer, an ionomer, a cellulosic resin, and a polycarbonate resin. If necessary, a release agent such as silicone oil may be added to the dye-receiving layer in order to prevent fusion between the thermal transfer sheet and the transfer-receiving body during thermal transfer. The thickness of the dye receiving layer is preferably about 2 to 20 μm.

As a means for applying thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the above-mentioned transfer receiving body, any conventionally known applying means can be used. By controlling the energy, a gradation image can be obtained.

<Action> As a dye, C.I. I. A mixture of Disperse Blue 24 and a dye represented by the general formula [1]; I. Disperse Blue 24 and C.I.
I. By using a mixture of Solvent Yellow 93 and the dye represented by the general formula [1], it was possible to obtain faithful color reproducibility with respect to the original image, sufficient color developability with low energy heat, high color density, and the like. It is possible to provide a cyan thermal transfer sheet capable of realizing high fastness of an image.

[0025]

Next, the present invention will be described more specifically with reference to examples. In the following description, parts or% are based on weight unless otherwise specified.

Example 1 An ink composition for a thermal transfer layer having the following composition was prepared and heat-treated on the back surface to a thickness of 5.4 μm.
m of a polyethylene terephthalate film having a dry film thickness of 1.5 μm and dried to obtain a thermal transfer sheet of the present invention. (Ink for thermal transfer layer) C.I. I. Disperse Blue 24 2.0 parts Dye represented by the following structural formula 2.0 parts Phenoxy resin 5.0 parts Methyl ethyl ketone 60.0 parts Toluene 31.0 parts

[0027]

Embedded image

(Wherein X represents any one of a hydrogen atom, an alkyl group, a formylamino group, an alkylcarbonylamino group, a benzoylamino group, an alkoxycarbonylamino group and a halogen atom, and Y represents a hydrogen atom, an alkyl group , An alkoxy group or a halogen atom, and R, R ¹ and R ² each represent an alkyl group or an allyl group.)

Next, a foamed polypropylene film (thickness: 50 μm) / adhesive resin layer / coated paper (108 g / m ² ) / adhesive resin layer / foamed polypropylene film (thickness: 50 μm) was used as a base sheet. The following ink for a dye receiving layer was applied to the surface so as to have a dry film thickness of 4 μm, dried, and then aged at 45 ° C. for one week to obtain a transfer-receiving material. (Dye receiving layer ink) Acetal resin 10.0 parts Vinyl chloride-vinyl acetate copolymer resin 10.0 parts Silicon oil 2.0 parts Isocyanate resin 3.0 parts Methyl ethyl ketone 50.0 parts Toluene 25.0 parts

The surface of the thermal transfer layer of the obtained thermal transfer sheet and the surface of the dye receiving layer of the transfer object were overlapped, and the dye was transferred under the following conditions using a thermal head to form an image. (Printing conditions) Printing machine: Simulator manufactured by SIP 300 dot / inch head Printing pattern: 16 gradation pattern Printing energy: 0.6 mJ / dot at 16th gradation

The following evaluation was performed on the obtained images. (Evaluation item) Coloring density: The reflection density of the 16th gradation was determined by Macbeth RD-9.
Measured at 18 Heat transfer resistance: Density reduction rate at 16th gradation after 8 hours at 70 ° C. Light resistance: Density reduction rate at 16th gradation after 80 hours irradiation with xenon fade meter The above items were evaluated. As a result, good results were obtained as follows. Further, the color reproducibility of cyan was also good. Coloring density: 2.4 Heat transfer resistance: 5% or less Light resistance: 3% or less

Example 2 A thermal transfer sheet was obtained in the same manner as in Example 1, except that the ink composition for the thermal transfer layer was changed to the following composition. (Ink for thermal transfer layer) C.I. I. Disperse Blue 24 2.0 parts C.I. I. Solvent Yellow 93 1.0 part Dye represented by the following structural formula 1.0 part Phenoxy resin 5.0 parts Methyl ethyl ketone 60.0 parts Toluene 31.0 parts

[0033]

Embedded image

The transfer member obtained in the same manner as in Example 1 was overlaid on the above-mentioned thermal transfer sheet, and image formation and evaluation were performed in the same manner as in Example 1. The evaluation results are as follows. Coloring density: 2.3 Heat transferability: 5% or less Light fastness: 3% or less The color reproducibility as cyan was also good.

Example 3 A thermal transfer sheet was obtained in the same manner as in Example 1 except that the ink composition for the thermal transfer layer was changed to the following composition. (Ink for thermal transfer layer) C.I. I. Disperse Blue 24 2.0 parts Dye represented by the following structural formula 2.0 parts Phenoxy resin 3.0 parts Butyral resin 2.0 parts Methyl ethyl ketone 60.0 parts Toluene 31.0 parts

[0036]

Embedded image

The transfer object obtained in the same manner as in Example 1 was overlaid on the above-mentioned thermal transfer sheet, and image formation and evaluation were performed in the same manner as in Example 1. The evaluation results are as follows. Coloring density: 2.4 Heat transferability: 5% or less Light fastness: 3% or less The color reproducibility of cyan was also good.

Example 4 A thermal transfer sheet was obtained in the same manner as in Example 1, except that the ink composition for the thermal transfer layer was changed to the following composition. (Ink for thermal transfer layer) C.I. I. Disperse Blue 24 2.0 parts C.I. I. Solvent Yellow 93 1.0 part Dye represented by the following structural formula 1.0 part Phenoxy resin 5.0 parts Silicon resin 0.05 part Methyl ethyl ketone 60.0 parts Toluene 31.0 parts

[0039]

Embedded image

The transfer member obtained in the same manner as in Example 1 was overlaid on the thermal transfer sheet, and an image was formed and evaluated in the same manner as in Example 1. The evaluation results are as follows. Coloring density: 2.3 Heat transferability: 5% or less Light fastness: 3% or less The color reproducibility of cyan was also good.

[0041]

By combining a specific dye, it is possible to obtain a thermal transfer sheet having excellent color reproducibility, sensitivity, color density, and fastness (heat transfer resistance, light resistance) of a formed image, especially for cyan. did it.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing one embodiment of a thermal transfer sheet according to the present invention using a cross-sectional view.

FIG. 2 is an explanatory view schematically showing another embodiment of the thermal transfer sheet according to the present invention using a cross-sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet 2 ... Base sheet 3 ... Thermal transfer layer 4 ... Back coat layer

Claims (3)

[Claims] 1. A thermal transfer sheet comprising a substrate sheet provided with a thermal transfer layer comprising a binder resin and a dye which is transferred by heating and transferred onto a transfer-receiving member, wherein the dye is C.I. I. A thermal transfer sheet comprising a mixture of Disperse Blue 24 and a dye represented by the following general formula [1]. Embedded image (In the formula, X represents any one of a hydrogen atom, an alkyl group, a formylamino group, an alkylcarbonylamino group, a benzoylamino group, an alkoxycarbonylamino group, and a halogen atom, and Y represents a hydrogen atom, an alkyl group, an alkoxy group. Or any of the halogen atoms,
R, R ¹ and R ² each represent either an alkyl group or an allyl group. ) 2. The dye in the thermal transfer layer is C.I. I. Disperse Blue 24 and C.I. I. 2. The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is a mixture of Solvent Yellow 93 and the dye represented by the general formula [1]. 3. The thermal transfer sheet according to claim 1, wherein the thermal transfer layer contains silicone oil or silicone resin.