JP3424760B2 - Thermal transfer sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer sheet. More specifically, the present invention relates to a thermal transfer sheet in which an ink layer containing a red dye excellent in sharpness is carried on a support. 2. Description of the Related Art Electrophotographic, ink jet, thermal transfer and the like have been proposed as color recording techniques. The thermal transfer recording method is considered to be advantageous because maintenance and operability of the apparatus are easy. Conventionally, red to magenta dyes applied to thermal transfer recording have been selected from disperse dyes, oil-soluble dyes and the like. Specifically, JP-A-59-78
896, JP-A-60-30392, JP-A-60-303
94, JP-A-60-131293, JP-A-60-159
091, JP-A-61-227092, JP-A-61-22
7093, JP-A-1-174490, JP-A-1-183
584, Japanese Patent Application Laid-Open No. 1-263082, Japanese Patent Application Laid-Open No. 4-8026
5 and many other proposals. 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. ,
Various quality characteristics are required, such as no problem in health and safety. From the above viewpoints, almost satisfactory red to magenta dyes have been found. However, with the development of color recording technology, a high-definition image quality close to that of the silver halide photographic method has been required. In order to satisfy this demand, the quality of the prior art was not satisfactory in sharpness. An object of the present invention is to provide a heat-sensitive transfer sheet satisfying the above-mentioned quality characteristics. Means for Solving the Problems The present inventors have conducted intensive studies in order to find a very clear red dye, and have reached the present invention. That is, the present invention provides the following general formula (1): (Wherein R ₁ and R ₂ each independently represent a hydrogen atom, a linear or branched alkyl group (C ₁ -C ₄ ) or an allyl group, and X represents an imino group or an oxygen atom. Y ₁ and Y ₂ each independently represent a hydrogen atom, a methyl group, a methoxy group or a halogen atom), and an ink layer containing a benzopyran-based compound represented by the formula: To a heat-sensitive transfer sheet. The compound represented by the general formula (1) is a compound represented by the general formula (2): (Wherein, R ₁ , R ₂ , Y ₁ and Y ₂ have the same meanings as described above) and an iminocoumarin represented by the formula (3): ## STR4 ## Can be produced by reacting malondinitrile represented by the formula (1) in an organic solvent, usually at a temperature of 50 to 200 ° C., and optionally hydrolyzing in water or an organic solvent in the presence of an acid. . In the heat-sensitive transfer sheet of the present invention, an ink is prepared by previously dissolving or dispersing the dye of the general formula (1) together with a binder in a medium in the form of fine particles. It is manufactured by coating and drying on a sheet-like support. As a binder for preparing the ink, for example, cellulose, acrylic acid,
One or two kinds of water-soluble resins such as starch, acrylic resin, methacrylic resin, polystyrene resin, polycarbonate resin, polysulfone resin, polyester resin, polyethersulfone resin, ethylcellulose and other organic solvents or water-soluble resins. Used above. 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 alone or as a mixture of two or more. As the support on which the ink is applied to prepare the heat-sensitive transfer sheet, a condenser paper, cellophane, or a plastic film having good heat resistance such as polyester, polyamide, polyimide, or polyethersulfone 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 thickness of the ink coating layer after drying is 0.1 to 10 μm, preferably 0.4 to 10 μm.
It is applied so as to have a thickness of up to 5.0 μm. Next, the ratio of the dye to the binder and the medium is 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, preferably 1 to 10% by weight. 4 to 12% by weight of a binder
The medium is 78 to 95% by weight. However, this ratio does not restrict the present invention. The receiving sheet is usually used as a receiving sheet such as paper coated with polyester resin or polyamide resin, synthetic paper such as polypropylene, polyvinyl chloride or polyester, and transparent sheet of synthetic resin such as polyester. Can be used as is. The present invention will be described in more detail by way of examples. In the examples, "parts" and "%" are parts by weight and% by weight, respectively. Production Example 1 Formula (4) 33.2 parts of the above compound and 7.3 parts of malondinitrile are suspended in 500 parts of ethanol and reacted under reflux for 10 hours. After confirming the completion of the reaction, the reaction mixture is cooled to room temperature and the crystals are separated by filtration. The obtained crystals are washed with ethanol, then with water, and dried to obtain the following formula (5). 32.4 parts of compound (mp 275 ° C.) were obtained. Production Example 2 16.2 parts of the compound of the formula (5) obtained in Production Example 1 was 30%
Dissolve in 72 parts of sulfuric acid. Next, the reaction is carried out at 100 to 105 ° C. for 10 hours. After confirming the completion of the reaction, the mixture is cooled to room temperature and neutralized with a 35% aqueous sodium hydroxide solution, and the crystals are separated by filtration. The obtained crystals are washed with water and dried to obtain the following formula (6). 15.4 parts of the compound (mp 273-275 ° C) were obtained. Example 1 1) Method of preparing ink An ink composition was prepared by treating a mixture comprising 2 parts of the dye of Preparation Example 2, 6 parts of ethyl cellulose, 46 parts of toluene and 46 parts of methyl ethyl ketone for 3 hours using a ball mill. did. 2) Method for preparing 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. The transfer sheet was good without crystal precipitation. 3) Preparation method of receiving sheet The receiving sheet is composed of 15 parts of polyester resin (manufactured by Nippon Gosei Co., Ltd., product name: TP-220), and 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 After curing, a receiving sheet was prepared. 4) Transfer Recording The ink-coated surface of the transfer sheet is overlapped with the receiving sheet from the back surface 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 is performed under the condition of a printing time of 6 milliseconds, λmax =
An extremely clear red uniform color of 555 μm was obtained. As a result of measuring the color density with a densitometer RD-914 (manufactured by Macbeth, USA), the result was as good as 1.28. Examples 2 to 5 Inks were prepared in the same manner as in Example 1 using 2.0 parts of the dye shown in Table 1, and then a transfer sheet was prepared. Transfer recording was performed in the same manner as in Example 1 using these transfer sheets. Recordings having high color densities as shown in Table 1 were obtained. Embedded image Table 1 Example ₁ R ₁ R ₂ XY ₁ Y ₂ λmax Color density 2 C ₂ H ₅ C ₂ H ₅ NH HH 552 1.26 3 C ₂ H ₅ C ₂ H ₅ NHH Cl 548 1.25 4 C ₂ H ₅ C ₂ H ₅ NH Cl Cl 547 1.235 C ₂ H ₅ C ₂ H ₅ OH Cl 551 1.276 C ₂ H ₅ C ₂ H ₅ O Cl Cl 550 257 C ₄ H ₉ C ₄ H ₉ NH HH 552 1.308 C ₄ H ₉ C ₄ H ₉ OHH 556 1.329 C ₄ H ₉ C ₄ H ₉ NHH Cl 548 1.28 10 C ₄ H ₉ C ₄ H ₉ OH Cl 552 1.29 11 CH ₂ CHCH ₂ CH ₂ CHCH ₂ NH HH 545 1.31 12 CH ₂ CHCH ₂ CH ₂ CHCH ₂ OHH 548 1.33 13 CH ₂ CHCH ₂ CH ₂ CHCH ₂ NH H CH ₃ 546 1.30 14 CH ₂ CHCH ₂ CH ₂ CHCH ₂ OH CH ₃ 551 1.31 15 CH ₂ CHCH ₂ CH ₂ CHCH ₂ NH H OCH ₃ 547 1.30 16 CH ₂ CHCH ₂ CH ₂ CHCH ₂ OH OCH ₃ 550 1.30 [0026], according to the present invention in accordance with the present invention particular Red Irosome By performing thermal transfer recording by thermal transfer sheet containing a very sharp high and the excellent color density gradation properties in hue Toledo image is obtained. Furthermore, since the color reproducibility is good and the light resistance, weather resistance, and heat resistance are excellent, an image can be recorded with high storability.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D06P 5/00 117 B41M 5/38 B41M 5/30 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] [Claim 1] The general formula (1) (Wherein, R ₁ and R ₂ each independently represent a hydrogen atom, a linear or branched alkyl group (C ₁ -C ₄ ) or an allyl group, X represents an imino group or an oxygen atom, and Y represents ₁ , Y
₍₂₎ each independently represents a hydrogen atom, a methyl group, a methoxy group or a halogen atom), wherein the ink layer containing a benzopyran-based compound represented by the formula (1) is supported on a support.