JPH0776177A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer sheet having magenta-violet colors of excellent gradationality, high color density and excellent preservability by carrying an ink layer containing monoazo compound of a specific structure on a support. CONSTITUTION:An ink layer containing monoazo compound represented by a formula (where X is H, a methyl group and Cl, and R is a 1-4C alkyl group) is carried on a support. When a thermal transfer recording is conducted by a thermal transfer sheet containing dyes of the magenta-violet colors, a magenta- violet image having excellent gradationality and high color density can be obtained. Further, since the obtained image has excellent color reproducibility, excellent light resistance, weather resistance and heat resistance, its preservability is excellent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive transfer sheet. More specifically, it relates to a heat-sensitive transfer sheet in which an ink layer containing a red dye having excellent sharpness is carried on a support.

[0002]

2. Description of the Related Art Electrophotography, 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 the maintenance and operability of the apparatus are easy. Conventionally, dyes used for thermal transfer recording easily sublime and do not undergo thermal decomposition under the heat of the thermal recording head, have a large molecular extinction coefficient, have good color reproducibility, light resistance, weather resistance and heat resistance. Various quality characteristics have been demanded, such as excellent properties and safety and health problems. From the above viewpoints, no satisfactory magenta to violet dyes have been found.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive transfer sheet from which a magenta-violet color transfer product satisfying the above quality characteristics can be obtained.

[0004]

The present invention has been accomplished as a result of intensive research to find a magenta-violet dye having excellent gradation, high color density, and good storage stability. That is, the present invention has the following formula (1)

[Chemical 2]

(In the formula (1), X is a hydrogen atom, a methyl group,
A thermal transfer sheet is provided which has an ink layer containing a monoazo compound represented by a chlorine atom, wherein R means an alkyl group having 1 to 4 carbon atoms, and is supported on a support.

The present invention will be described in detail. The compound represented by the formula (1) in the present invention is known in JP-A-63-4593 and is known to dye hydrophobic fibers in reddish purple. It is also known that this dye is a dye suitable for discharge prevention, but it is not known to be used for a thermal transfer sheet. The present inventors have found that as a result of including the compound represented by the formula (1) in a thermal transfer sheet, magenta to violet color image recording having excellent gradation, high color density and good storage can be obtained. It is a thing.

In the heat-sensitive transfer sheet of the present invention, an ink is prepared by previously dissolving the dye of the formula (1) together with a binder in a medium or dispersing it in the form of fine particles, and the ink is a sheet such as a plastic film or paper. It is manufactured by coating on a flat support and drying. As the binder for ink preparation, 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 water-soluble resin may be used alone or in combination of two or more.

Water as a medium for ink preparation; 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; Chlorine solvents such as methylene chloride, chloroform, dichloroethane and trichloroethane; Acetic acid esters such as ethyl acetate and butyl acetate; Ethers such as tetrahydrofuran and dioxane; N, N -Dimethylformamide,
Organic solvents such as N-methylpyrrolidone and dimethylimidazolidinone are used alone or as a mixture of two or more.

As a support to which the ink is applied for producing a heat-sensitive transfer sheet, condenser paper, cellophane, or a plastic film having good heat resistance such as polyester, polyamide, polyimide or polyether sulfone is used.

The ink can be applied onto the support by using a bar coater, a roll coater, a knife coater, a gravure printing machine or the like. The thickness of the ink coating layer is 0.1 to 10 μm after drying, preferably 0.4.
It is applied so that the thickness becomes ˜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 of the dye. , 4 to 12% by weight of binder,
The medium is 78 to 95% by weight. However, this ratio does not restrict the present invention.

As the receiving sheet, paper coated with polyester resin or polyamide resin, synthetic paper such as polypropylene, polyvinyl chloride or polyester, and transparent sheets of synthetic resin such as polyester are usually used as the receiving sheet. You can use what you have.

[0012]

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.

Example 1 1) Method of preparing ink (2)

[Chemical 3]

2 parts of the compound (dye) represented by: 6 parts of ethyl cellulose, 46 parts of toluene, 4 parts of methyl ethyl ketone
An ink was prepared by treating a mixture of 6 parts with a ball mill for 3 hours. 2) Method for producing transfer sheet Using a bar coater, the above ink composition was applied to a polyethylene terephthalate (PET) film to give a dry film thickness of 1 μm.
To obtain a transfer sheet. The transfer sheet of this product was good with no crystal precipitation. 3) Preparation method of receiving sheet The receiving sheet is 15 parts of polyester resin (manufactured by Nippon Gosei Co., Ltd., product name: TP-220), amino-modified silicone (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF393) 0.5.
Part, 20 parts of methyl ethyl ketone, and 10 parts of xylene were applied to a composition for receiving sheet of 150 μm on a synthetic paper (manufactured by Oji Yuka Co., Ltd., product name: FPG-150) to a dry film thickness of about 5 μm. Curing was performed at 30 ° C. for 30 minutes to prepare a receiving sheet. 4) Transfer recording Using a thermal head having a receiving sheet and a back surface of the superposed transfer sheet on the ink application surface of the transfer sheet, a thermal head having a heating resistor of 250Ω at a density of 4 dots / mm, an applied voltage of 10 V,
When heating recording is performed under the condition that the printing time is 5 milliseconds, λmax =
Uniform recording was obtained with an extremely clear red color of 565 μm. As a result of measuring the color density with a densitometer RD-914 (manufactured by Macbeth, USA), the result was 1.32, which was excellent.

Examples 2 to 5 Inks were prepared in the same manner as in Example 1 using 2.0 parts of the dyes shown in Table 1, and then transfer sheets were prepared.
In addition, X and R in Table 1 mean X and R in the formula (1). Transfer recording was performed in the same manner as in Example 1 using these transfer sheets. As a result, the recordings with high color density shown in Table 1 were obtained.

[0016]

[Chemical 4]

[0017]

[Table 1]

[0018]

When thermal transfer recording is carried out using the heat-sensitive transfer sheet containing the magenta-violet color dye of the present invention, a magenta-violet image having excellent gradation and high color density can be obtained. Further, the obtained image has good color reproducibility and excellent light resistance, weather resistance, and heat resistance, and therefore has good storage stability.

Claims (1)

[Claims] 1. A formula (1): (In the formula (1), X represents a hydrogen atom, a methyl group, a chlorine atom, and R represents an alkyl group having 1 to 4 carbon atoms), and an ink layer containing a monoazo compound represented by the formula is carried on a support. A heat-sensitive transfer sheet characterized by being made.