JP3058520B2 - 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. More specifically, the present invention relates to a thermal transfer sheet in which an ink layer containing a magenta dye having excellent sublimation property is supported on a support.

[0002]

2. Description of the Related Art As a color recording technique, a recording method using electrophotography, ink jet, thermal transfer and the like has been proposed. Among them, the thermal transfer recording method is considered to be advantageous because maintenance and operability of the apparatus are easy. Conventionally, magenta dyes applied to thermal transfer recording have been selected from disperse dyes, oil-soluble dyes and the like. For example, JP
2-55194 and Japanese Patent Application Laid-Open No. 1-263082 propose an azo compound having a heteroaromatic ring. The dye used in the transfer sheet is easily sublimated by the heat of the thermal recording head and does not cause thermal decomposition, has a large molecular extinction coefficient, has good color reproducibility, and has excellent light resistance, weather resistance, and heat resistance. Quality characteristics such as no problem in safety and health are required. No magenta dye has yet been found which satisfies these quality characteristics.

[0003]

SUMMARY OF THE INVENTION The present invention provides a thermal transfer sheet containing a magenta dye satisfying the above-mentioned quality characteristics.

[0004]

Means for Solving the Problems As a result of intensive studies for finding a magenta dye having good quality characteristics, the present invention has been achieved. That is, the present invention provides a mixture containing the compounds represented by the following general formulas (1) -1 and (1) -2.

[0005]

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Wherein Y is a hydrogen atom, an alkyl group (C ₁
To C ₄ ), which represents an acylamino group. R _1, R ₂ each independently represent an alkyl group (C ₁ ~C _4), an alkoxyalkyl group (C ₁ ~C _4), phenylalkyl group (C ₁ ~C _4), cyanoalkyl group (C ₁ -C ₄ ), a hydroxyalkyl group (C ₁ -C ₄ ), an alkoxycarbonylalkyl group (C ₁
To C ₄ ), an alkoxycarbonyloxyalkyl group (C ₁
Means ~C _4). The present invention provides a heat-sensitive transfer sheet characterized in that an ink layer containing (1) is carried on a support.

[0007] A mixture containing the compounds represented by the general formulas (1) -1 and (1) -2 is prepared by the following method.

[0008]

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The 2-aminobenzothiazole represented by the general formula (3) is diazotized by a known method.

[0010]

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(Wherein, Y, R ₁ and R ₂ have the same meanings as described above). The diazo component used in the present invention comprises 2-amino-5,6-dichlorobenzothiazole and 2-amino-5,6-dichlorobenzothiazole.
It is a mixture of amino-6,7-dichlorobenzothiazole, and the mixture ratio can be arbitrarily, but is about 1:
1 is preferred.

In the heat-sensitive transfer sheet of the present invention, a mixture (colorant) containing the compounds of the formulas (1) -1 and (1) -2 is dissolved or dispersed in a medium together with a binder in advance in a medium. Is prepared by applying the ink on a sheet-like support such as a plastic film or paper and drying. As a binder for preparing the ink, for example, cellulose-based, acrylic acid-based, starch-based water-soluble resin, acrylic resin, methacrylic resin, polystyrene resin, polycarbonate resin, polysulfone resin, polyester resin, polyether sulfone resin, An organic solvent such as ethyl cellulose or a resin soluble in water is used alone or in combination of two or more.

Water is used as a medium for preparing the ink; alcohols such as methanol, ethanol and butanol;
Cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; toluene,
Aromatic hydrocarbons such as xylene and chlorobenzene; chlorinated solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethane; acetates such as ethyl acetate and butyl acetate; ethers such as tetrahydrofuran and dioxane; -Dimethylformamide,
Organic solvents such as N-methylpyrrolidone and dimethylimidazolidinone are used as one kind or as a mixture of two or more kinds.

As the support on which the ink is applied for preparing the thermal transfer sheet, a condenser paper, cellophane or a plastic film having good heat resistance such as polyester, polyamide, polyimide, polyethersulfone or the like is used.

As a method for applying the ink on the support, it can be carried out using a bar coater, a roll coater, a knife coater, a gravure printing machine or the like. The ink coating layer is applied so that the thickness after drying is 0.1 to 10 μm, preferably 0.4 to 5.0 μm. Next, the proportions of the dye, binder and medium used in the ink preparation are usually 0.5 to 15% by weight of the dye, 3 to 15% by weight of the binder, 70 to 96.5% of the medium, and preferably 1 to 5%. 10% by weight, 4 to 12% by weight of the binder, and 78 to 95% by weight of the medium.

The receiving sheet is usually used as a receiving sheet such as paper coated with a resin such as polyester resin or polyamide resin, synthetic paper such as polypropylene, polyvinyl chloride or polyester, and transparent sheets of synthetic resin such as polyester. What is done can be used as it is.

[0017]

The present invention will be described in more detail with reference to examples. In the examples, "parts" and "%" are parts by weight and% by weight, respectively.

Production Example 1 2-amino-5,6-dichlorobenzothiazole and 2-amino-5,6-dichlorobenzothiazole
After 11 parts of a 1: 1 mixture of amino-6,7-dichlorobenzothiazole was dissolved in 93 parts of concentrated sulfuric acid, 63 parts of water was added dropwise at 40 ° C. or lower. This is cooled to -4 ° C and
After dropping 21 parts of 0% nitrosylsulfuric acid,
After stirring for a time, a diazo liquid was obtained. On the other hand, 10.4 parts of N-cyanoethyl-N-ethyl-m-toluidine was added to 50 parts of acetic acid.
To prepare a coupler solution. The diazo solution was added dropwise to this prepared solution at 0 to 5 ° C., and the obtained compound was filtered, washed with water, and dried to obtain 17.8 parts of the following formula compounds (5) and (6) in a ratio of 1: 1. A mixture was obtained. Its λmax was 522 nm (in ethanol).

[0019]

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[0020]

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Example 1 1) Preparation of Ink 2 parts of the dye obtained in Production Example 1, 6 parts of ethyl cellulose,
A mixture consisting of 46 parts of toluene and 46 parts of methyl ethyl ketone was treated for 3 hours using a ball mill to obtain an ink composition. 2) Preparation of transfer sheet The above ink composition was applied to a polyethylene terephthalate (PET) film with a dry film thickness of 1 μm using a bar coater.
To obtain a transfer sheet of the present invention. The transfer sheet was good without crystal precipitation. 3) Preparation of Receiving Sheet The receiving sheet was composed of 15 parts of a polyester resin (manufactured by Nippon Gosei Co., Ltd., product name: TP-220), 0.5 part of amino-modified silicone (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF393)
Part, 20 parts of methyl ethyl ketone, and 10 parts of xylene, was applied to 150 μm synthetic paper (manufactured by Oji Yuka Co., Ltd., product name: FPG-150) so as to have a dry film thickness of about 5 μm, and 100 ° C. for 30 minutes. It was produced by curing. 4) Transfer Recording The transfer sheet is coated with the ink-coated surface and the receiving sheet from the back side of the transfer sheet. The applied voltage is 10 V using a thermal head having a heating resistor of 250Ω at a density of 4 dots / mm.
When heating recording was performed under the condition of a printing time of 6 milliseconds, uniform recording was obtained in a clear magenta color. Densitometer RD
As a result of measuring the color density with -914 (manufactured by Macbeth, USA), the result was 1.25, which was good.

Examples ₂ to 13 Using 2.0 parts of a dye in which Y, R ₁ and R _{2 in the} above formulas (1) -1 and (1) -2 are each a substituent shown in Table 1 below. An ink was prepared in the same manner as in Example 1, and then a transfer sheet of the present invention was prepared. Transfer recording was performed in the same manner as in Example 1 using these transfer sheets. In addition, recordings having high magenta color densities shown in Table 1 were obtained.

[0023]

Table 1 Example Y R ₁ R ₂ λmax Color density 2-CH ₃ -C ₂ H ₅ -C ₂ H ₅ 539 1.23 3-CH ₃ -C ₂ H ₄ OCH ₃ -C ₂ H ₄ OCH ₃ 534 1.23 4-CH ₃ -C ₂ H ₄ OH -C ₂ H ₄ OH 531 1.19 5-CH ₃ -C ₂ H ₄ COOCH ₃ -C ₂ H ₄ COOCH ₃ 520 1.216 -H -C ₂ H ₅ -C ₂ H ₄ C ₆ H ₅ 522 1.19 7 -H -CH ₃ -C ₃ H ₆ C ₆ H ₅ 527 1.19 8 -H -C ₂ H ₄ OCH ₃ -C ₂ H ₄ OCH ₃ 521 1.23 9 -H -C ₄ H ₉ -C ₄ H ₉ 533 1.22 10 -NHCOCH ₃ -C ₂ H ₅ -C ₂ H ₅ 541 1.18 11 -NHCOCH ₃ -C ₂ H ₄ COOCH ₃ -C ₂ H ₄ COOCH ₃ 527 1.19 12 -NHCOCH ₃ -C ₂ H ₅ -C ₂ H ₄ CN 525 1.21 13 -NHCOCH ₃ -C ₂ H ₄ OCOCH ₃ -C ₂ H ₄ OCOCH ₃ 530 1.19

[0025]

As described above, a heat-sensitive transfer sheet which is excellent in gradation and gives a magenta image having a high color density was obtained. The obtained image has excellent light fastness, weather fastness, heat resistance and high storage stability.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40 CAPLUS (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A mixture containing compounds represented by the general formulas (1) -1 and (1) -2. (Wherein, Y represents a hydrogen atom, an alkyl group (C ₁ -C ₄ ), or an acylamino group. R ₁ and R ₂ each independently represent an alkyl group (C ₁ -C ₄ ) or an alkoxyalkyl group (C ₁ ~
C _4), phenylalkyl group (C ₁ ~C _4), cyanoalkyl group (C ₁ ~C _4), a hydroxyalkyl group (C ₁ ~
C ₄ ), alkoxycarbonylalkyl group (C _1-
C ₄ ), an alkoxycarbonyloxyalkyl group (C _1-
C ₄ ). A) a heat-sensitive transfer sheet, wherein an ink layer containing the above (1) is carried on a support.