JPH085255B2 - 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 heat-sensitive transfer method includes a base film and a transfer sheet 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 greatly affects the transfer recording speed, the image quality of the recorded matter, the storage stability, etc. Need 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 represents an alkyl group, an optionally substituted alkoxyalkyl group, an allyl group, a cycloalkyl group, a tetrahydrofurfuryl group, a furfuryl group or an aralkyl group). And a heat-sensitive transfer sheet having a color material layer containing the dye on a base film.

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

The alkyl group of R in the above formula [I] is a methyl group,
Examples thereof include linear or branched C ₁ -C ₈ alkyl groups such as ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group.

The alkoxyalkyl group which may be substituted 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
- ethoxy butyl group, 1-ethyl-2-methoxyethyl group, 1-ethyl -2-ethoxyethyl group is particularly β- alkoxyethyl group C ₃ -C ₈ preferred. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the aralkyl group include a benzyl group and a β-phenylethyl group.

As a method for producing the above-mentioned dye of the present invention, for example, the following general formula [II] (Wherein R is the same as the above definition) can be obtained by diazotizing a compound represented by the above formula and coupling it to 1-phenyl-3-methyl-5-hydroxypyrazole.

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 the dye in a medium or dispersing it in the form of fine particles together with a binder, and the ink is used 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 preparing the ink, cellulose-based,
Acrylic acid-based, starch-based and other water-soluble resins, acrylic resins, methacrylic resins, polystyrene, polycarbonate, polysulfones, polyether sulfones, polyvinyl butyral, ethyl cellulose, acetyl cellulose, and other organic solvents or water-soluble resins. it can.

As a medium for ink preparation, in addition to water, alcohols such as methyl alcohol, isopropyl alcohol and isobutyl alcohol, methyl cellosolve, cellosolves such as ethyl cellosolve, aromatics such as toluene, xylene and chlorobenzene, ethyl acetate, Butyl acetate and other esters, 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-methyl Organic solvents such as pyrrolidone can be mentioned.

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 of the thermal head is insufficient. Therefore, by providing a layer of a heat-resistant resin containing a surfactant and heat-resistant particles with high lubricity on the opposite surface of the color material layer,
The runnability of the thermal head can be improved.

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 slip-treated with a wire bar was used.
m) and then dried (dry film thickness: 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 Chemical Co., Ltd. product) 0.5 part, 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.
Records of 20 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 conducted using a carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.) (black panel temperature 63 ± 2 ° C.), but almost no discoloration or fading 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 clear 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 safe against heat, light, moisture, chemicals, etc., it is not thermally decomposed during transfer recording, and the obtained record is excellent in storability and particularly excellent in light resistance.
Further, since the dye has good solubility in an organic solvent and dispersibility in water, it is easy to prepare a high-concentration ink that is uniformly dissolved or dispersed. It is possible to obtain a heat-sensitive transfer sheet which is uniformly applied in high concentration. 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 represents an alkyl group, an optionally substituted alkoxyalkyl group, an allyl group, a cycloalkyl group, a tetrahydrofurfuryl group, a furfuryl group or an aralkyl group). . 2. The following general formula [I] is formed on a base film. (Wherein R represents an alkyl group, an optionally substituted alkoxyalkyl group, an allyl group, a cycloalkyl group, a tetrahydrofurfuryl group, a furfuryl group or an aralkyl group), and a coloring material containing a pyrazolone azo dye. A heat-sensitive transfer sheet having a layer.