JPH085254B2 - Dye for thermal transfer recording and thermal transfer sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel thermal transfer recording dye and a thermal transfer sheet.

(Prior Art) Conventionally, there has been a demand for a technology for color recording a facsimile printer, a copying machine, a television image or the like, and a color recording technology by electrophotography, ink jet, thermal transfer or the like has been studied.

The thermal transfer recording method is considered to be advantageous as compared with other methods because the apparatus is easy to maintain and operate and the apparatus and consumables are inexpensive.

The thermal transfer system includes a base film and a base film having a heat-meltable ink layer formed thereon. The transfer sheet is heated by a heat-sensitive head to melt the ink, and transfer recording is performed on a recording medium. There is a sublimation method in which a transfer sheet on which an ink layer containing a sublimable dye is formed is heated by a thermal head to sublimate the dye, and transfer recording is performed on a recording medium, but the sublimation method is a thermal head. Since the sublimation transfer amount of the dye can be controlled by changing the applied energy, gradation recording becomes easy, which is considered to be particularly advantageous for full-color recording.

In sublimation thermal transfer recording, the sublimable dye used in the transfer sheet is very important because it has a great influence on the transfer recording speed, the image quality of the recorded matter, storage stability, etc. It is necessary to fill.

 Easily sublimate under the operating conditions of the thermal recording head.

 Do not thermally decompose under the operating conditions of the thermal recording head.

 It should have a favorable hue for color reproduction.

 Large molecular extinction coefficient.

 Stable against heat, light, moisture, chemicals, etc.

 Easy synthesis.

 Excellent ink suitability.

 There are no safety and health problems.

A dye satisfying all the above conditions has not been found so far, and a yellow dye, in particular, has various drawbacks and no satisfactory dye has been found yet.

(Problems to be Solved by the Invention) The present invention provides a novel yellow-colored pyrazolone azo type heat-sensitive transfer recording dye satisfying all of the above conditions, and a heat-sensitive transfer sheet using the dye. With the goal.

(Means for Solving Problems) The present invention provides the following general formula [I]. (In the formula, R is an optionally substituted alkoxyalkyl group, an optionally substituted alkyloxyalkyl group,
A tetrahydrofurfuryl group, a furfuryl group, an optionally substituted allyloxyalkyl group, or an optionally substituted aryloxyalkyl group), which is a pyrazolone azo type heat-sensitive transfer recording dye and a color containing the dye. The heat transfer sheet is characterized by having a material layer on a base film.

The pyrazolone azo dye represented by the above general formula [I] of the present invention will be described.

In the above general formula [I], the optionally substituted alkoxyalkyl group represented by R is 2-methoxyethyl group, 2-ethoxyethyl group, 2- (n) propoxyethyl group, 2- (iso). Propoxyethyl group, 2
-(N) butoxyethyl group, 2- (iso) butoxyethyl group, 2- (sec) butoxyethyl group, 2- (n) pentyloxyethyl group, 2- (n) hexyloxyethyl group, 2- (n ) Octyloxyethyl group, 2- (2-ethylhexyloxy) ethyl group, 1-methyl-2-methoxyethyl group, 1-methyl-2-ethoxyethyl group, 1
-Methyl-2- (n) propoxyethyl group, 1-methyl-2- (iso) propoxyethyl group, 1-methyl-2-
(N) butoxyethyl group, 1-methyl-2- (iso) butoxyethyl group, 1-methyl-2- (n) hexyloxyethyl group, 1-methyl-2- (2-ethylhexyloxy) ethyl group, 3 -Methoxybutyl group, 3-ethoxybutyl group, 1-ethyl-2-methoxyethyl group, 1-ethyl-2ethoxyethyl group and the like, and the optionally substituted aralkyloxyalkyl group is 2-benzyloxy. Examples thereof include an ethyl group, a 1-methyl-2-benzyloxyethyl group, a 1-ethyl-2-benzyloxyethyl group, a 2- (β-phenylethyl) oxyethyl group, and the allyloxyalkyl group which may be substituted. Is a 2-allyloxyethyl group, 1-methyl-2
Examples thereof include an allyloxyethyl group and a 1-ethyl-2-allyloxyethyl group, and examples of the optionally substituted aryloxyalkyl group include a 2-phenoxyethyl group, a 1-methyl-2-phenoxyethyl group, and a 1-methyl-2-phenoxyethyl group. Examples include an ethyl-2-phenoxyethyl group.

As a method for producing the above dye, for example, o-trifluoromethylaniline is diazotized by a usual method to give 1-
An azo dye obtained by coupling with phenyl-3-ethoxycarbonyl-5-hydroxypyrazole is used in an alcohol represented by the following general formula [II] R-OH [II] (in the formula, R is the same as the above definition). It can be carried out by performing a transesterification reaction using a basic catalyst such as sodium methoxide.

As a method for producing the heat-sensitive transfer sheet of the present invention using the above-mentioned dye of the present invention, an ink is prepared by dissolving or dispersing the dye in a medium together with a binder, and the ink is prepared as a base film. A color material layer is formed on the base film by applying and drying it on the base film.

As a binder for ink preparation, an acrylic resin,
Examples thereof include resins soluble in organic solvents such as methacrylic resin, polystyrene, polycarbonate, polysulfone, polyester, polyether sulfone, polyvinyl butyral, ethyl cellulose and acetyl cellulose.

As a medium for ink preparation, alcohols such as methyl alcohol, isopropyl alcohol and isobutyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, aromatics such as toluene, xylene and chlorobenzene, ethyl acetate, butyl acetate and the like. Ester, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones, methylene chloride, chloroform, trichlorethylene and other chlorine-based solvents, tetrahydrofuran, dioxane and other ethers, N, N-dimethylformamide, N-methylpyrrolidone and other Mention may be made of organic solvents.

In addition to the above components, organic or inorganic non-sublimable fine particles, a dispersant, an antistatic agent, an antiblocking agent, an antifoaming agent, an antioxidant, a viscosity modifier, etc. are added to the above ink in the ink. can do.

The base film to which the ink for producing the transfer sheet is applied includes condenser paper, thin paper such as glassine paper, polyester, polycarbonate, polyamide,
Plastic films having good heat resistance such as polyimide and polyaramid are suitable, and the thickness thereof can be in the range of 3 to 50 μm.

Among the above base films, polyethylene terephthalate film is particularly advantageous in consideration of mechanical strength, solvent resistance, economy, etc., but in the case of the film, the heat resistance is not always sufficient, and the running performance of the thermal head is insufficient. Therefore, the runnability of the thermal head can be improved by providing a layer of a heat-resistant resin containing a surface-active agent and heat-resistant particles having a high lubricant on the opposite surface of the color material layer.

As a method of applying the ink to the base film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or the like can be used, and the thickness of the ink application layer is 0.1 to 5 μm after drying. It should be applied so that it becomes (Yuji Harasaki, Maki Shoten 19
Issued in 1979, "Coating method").

(Examples) The present invention will be specifically described below with reference to examples, but the examples do not limit the present invention.

Example 1 a) Ink preparation The mixture having the above composition was treated with a paint conditioner for 10 minutes to prepare an ink.

b) Preparation of transfer sheet Polyethylene terephthalate film (6 μm) whose back surface was heat-resistant and lubricated with a wire bar was used.
(thickness m) and then dried (dry film about 1 μm) to obtain a transfer sheet. In addition, the polyethylene terephthalate film has the following heat-resistant lubricity treatment. A liquid consisting of 8 parts by weight of a polycarbonate resin having a repeating structural unit represented by, 1 part by weight of a phosphoric acid ester-based surfactant (trade name: Plysurf A-208B: a product of Dai-ichi Kogyo Seiyaku Co., Ltd.), and 91 parts by weight of toluene. Was applied and dried (dry film thickness: about 0.5 μm).

c) Preparation of image receptor 10 parts of saturated polyester resin (product name: TP-220, product of Nippon Gosei Co., Ltd.), amino-modified silicone (product name: KF3)
93, Shin-Etsu Scientific Co., Ltd. product) 0.5 parts, methyl ethyl ketone 15 parts, xylene 15 parts liquid on synthetic paper (Product name: YUPO FPG150, Oji Yuka Co., Ltd. product) with a wire bar and dry (dry film thickness) An image receptor was prepared by further heat-treating in an oven at 100 ° C. for 30 minutes.

d) Transfer recording The ink-coated surface of the transfer sheet was overlaid on the recording medium and a thermal head was used to record under the following conditions.
A record of 22 uniform color densities could be obtained.

Recording conditions Linear density for main scanning and sub-scanning: 8 dots / mm Recording power: 0.25 W / dot Heating time for head: 10 msec Color density is Densitometer TR manufactured by Macbeth Co., USA
It was measured using a -927 type.

The light resistance test of the obtained record was carried out using a carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.) (black panel temperature 63 ± 2 ° C.), but almost no discoloration occurred after irradiation for 40 hours. Further, the transfer sheet and the record were stable against heat and humidity, and had excellent storage stability in the dark.

Example 2 The dyes shown in Table 1 were used in place of the dyes used in Example 1, and ink was prepared, a transfer sheet was prepared, and transfer recording was carried out in the same manner as in Example 1, and the results are shown in Table 1. A clear yellow color record having the indicated color density could be obtained.

The results of the light resistance test of the obtained record and the darkness storage stability test of the transfer sheet / record were good.

(Effects of the Invention) The pyrazolone azo type thermal transfer recording dye of the present invention has a vivid yellow color, and therefore is suitable for obtaining a full-color recording with good color reproducibility by combining with an appropriate magenta color and cyan color. In addition, since sublimation is easy and the molecular extinction coefficient is large, it is possible to obtain high-speed recording with high color density without imposing a heavy burden on the thermal head. Furthermore, since it is stable against heat, light, moisture, chemicals, etc., it does not decompose thermally during transfer recording, and the resulting record is excellent in storability and particularly excellent in light resistance.
In addition, since the dye has good solubility in an organic solvent, it is easy to prepare a high-concentration ink that is uniformly dissolved. By using these inks, the dye can be uniformly applied at a high concentration. It is possible to obtain a heat-sensitive transfer sheet. Also, there is no problem in terms of safety and health. Therefore,
By using such a heat-sensitive transfer sheet, it is possible to obtain a recording with good uniformity and color density.

Further, the heat-sensitive transfer sheet of the present invention can utilize not only a heat-sensitive head but also infrared rays, laser light and the like as a heating means.

Claims (2)

[Claims] 1. The following general formula [I] (In the formula, R is an optionally substituted alkoxyalkyl group, an optionally substituted aralkyloxyalkyl group, a tetrahydrofurfuryl group, a furfuryl group, an optionally substituted allyloxyalkyl group, or a substituted Which represents an optionally substituted aryloxyalkyl group), a pyrazolone azo type thermal transfer recording dye. 2. The following general formula [I] is formed on a base film. (In the formula, R is an optionally substituted alkoxyalkyl group, an optionally substituted aralkyloxyalkyl group, a tetrahydrofurfuryl group, a furfuryl group, an optionally substituted allyloxyalkyl group, or a substituted A heat-sensitive transfer sheet having a coloring material layer containing a pyrazolone azo dye represented by (which may represent an aryloxyalkyl group).