JPH085253B2 - Dye for thermal transfer recording and thermal transfer sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dye and a transfer sheet used for sublimation thermal transfer recording.

(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 transfer method in which a transfer sheet having a heat-meltable ink layer formed on a base film is heated by a heat-sensitive head to melt the ink, and transfer recording is performed on a recording medium, and a base film. 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, it is considered to be particularly advantageous for full-color recording because the halftone recording becomes easy.

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, 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.

A dye satisfying all of the above conditions has not been found so far, and particularly, a yellow dye has various defects and no satisfactory dye has been found yet.

(Problems to be Solved by the Invention) An object of the present invention is to provide a yellow dye for heat-sensitive transfer recording which satisfies all the above conditions, and a heat-sensitive transfer sheet using the dye.

(Means for Solving the Problem) The present invention has the following general formula [I]. (In the formula, R ¹ represents a C _{1 to} C ₈ alkyl group, a C _{3 to} C ₈ alkoxyalkyl group, a cycloalkyl group or an allyl group,
R ² represents a methyl group, a cycloalkyl group or an allyl group), which is a thermal transfer sheet characterized by having a pyridone azo type dye for thermal transfer recording and a coloring material layer containing the dye. Is.

The pyridone azo dye represented by the general formula [I] used in the present invention will be described.

As the C _{1 to} C ₈ alkyl group for R ¹ , a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,
Examples thereof include a heptyl group and an octyl group, which may be linear or branched, but a C ₁ -C ₄ lower alkyl group is particularly preferable. Examples of the alkoxyalkyl group C ₃ ~C _8, β- methoxyethyl group, beta-ethoxyethyl, beta-(n) propoxyethyl group, β- (iso) propoxy ethyl group, β- (n) butoxyethyl , Β-
(Iso) butoxyethyl group, β- (sec) butoxyethyl group, β- (n) pentoxyethyl group, β- (n) hexylethyl group, 1-methyl-2-methoxyethyl group, 1-
A methyl-2-ethoxyethyl group, a 3-methoxybutyl group, a 3-ethoxybutyl group, a 1-ethyl-2-methoxyethyl group, a 1-ethyl-2-ethoxyethyl group and the like can be mentioned, but especially C _{3 to} C ₆ The β-alkoxyethyl group of is preferred. As the cycloalkyl group, a cyclopentyl group,
A cyclohexyl group may be mentioned.

Examples of the cycloalkyl group for R ² include a cyclopentyl group and a sixcohexyl group.

The dye for thermal transfer recording represented by the above general formula [I] of the present invention is produced according to the method usually used for producing this kind of compound. For example, the following structural formula [II] (In the formula, R ¹ is the same as the above definition) The compound represented by the following general formula [III] (Wherein R ² is the same as the above definition).

When the above-mentioned dye is applied to the heat-sensitive transfer sheet 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 applied onto a base film and dried. To form a color material layer on the base film.

As a binder for preparing the ink, cellulose-based,
Acrylic acid-based and starch-based 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 can be mentioned. .

As a medium for ink preparation, in addition to water, 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 and acetic acid. Butyl and other esters, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones, methylene chloride, chloroform, trichlorethylene and other chlorinated 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.

As a method for 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 coating layer is within a range of 0.1 to 5 μm after drying. You can apply it as you like (Yuji Harasaki, Maki Shoten, 1979, "Coating method").

(Operation and Effect of the Invention) Since the pyridone azo type dye for thermal transfer recording represented by the above general formula [I] of the present invention has a clear yellow color, color reproduction by combining with an appropriate magenta color and cyan color is possible. It is suitable for obtaining full-color recording with good properties, and because it is easy to sublime and has a large molecular extinction coefficient, recording with high color density can be obtained at high speed 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. 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. 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.

(Example) Hereinafter, the present invention will be specifically described 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) Work 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 is subjected to the heat-resistant lubricity treatment by applying the following formula Composed of 8 parts by weight of a polycarbonate resin having a repeating structural unit represented by: 1 part by weight of a phosphate ester-based interfacial lubricant (trade name: PRYSURF A-208B: Dai-ichi Kogyo Seiyaku Co., Ltd.), and 91 parts by weight of toluene. It was performed by applying the liquid and drying (dry film thickness of about 0.5 μm).

c) Preparation of image receptor 10 parts of saturated polyester resin (product name: TP-220, manufactured by 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 superposed on the recording medium and a thermal head was used to record under the following conditions.
A record of 95 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 Head heating time: 10 msec Color density is densitometer RD- manufactured by Macbeth, Inc.
It was measured using a model 514 (filter: Ratten No. 47).

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 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 In the same manner as in Example 1 except that the dyes shown in Table 1 were used instead of the dyes used in Example 1, the ink was prepared, the transfer sheet was prepared, and the transfer recording was carried out. 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.

Claims (2)

[Claims] 1. The following general formula [I] (In the formula, R ¹ represents a C _{1 to} C ₈ alkyl group, a C _{3 to} C ₈ alkoxyalkyl group, a cycloalkyl group or an allyl group, and R ² represents a methyl group, a cycloalkyl group or an allyl group) A pyridoneazo dye for thermal transfer recording as shown in. 2. A base film having the following general formula [I] (In the formula, R ¹ represents a C _{1 to} C ₈ alkyl group, a C _{3 to} C ₈ alkoxyalkyl group, a cycloalkyl group or an allyl group, and R ² represents a methyl group, a cycloalkyl group or an allyl group) A heat-sensitive transfer sheet having a coloring material layer containing a pyridone azo dye.