JPH0815817B2 - Pyrazolone azo type heat-sensitive transfer recording dye and heat-sensitive transfer sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pyrazolone azo type dye for thermal transfer recording used for sublimation type thermal transfer recording, and a thermal transfer sheet using the dye.

(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 greatly affects the transfer recording speed, the image quality of the recorded matter, the storage safety, 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, A and B represent a lower alkyl group, a lower alkoxy group, a halogen atom, or a benzene ring which may be substituted with a nitro group, and R represents an alkyl group, an alkoxyalkyl group, an allyl group, a cycloalkyl group or A heat-sensitive transfer sheet characterized by comprising a pyrazolone azo type heat-sensitive transfer recording dye represented by (representing an aralkyl group) and a color material layer containing the dye on a base film.

The pyrazolone azo type thermal transfer recording dye represented by the general formula (I) of the present invention will be described.

Examples of the lower alkyl group which can be substituted on the benzene rings A and B include a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group and an octyl group. Can be mentioned especially C ₁
Alkyl group -C ₄ are preferred. Examples of the lower alkoxy group include a methoxy group, an ethoxy group, a linear or branched propoxy group and a butoxy group. Examples of the halogen atom include fluorine atom, chlorine atom and bromine atom, and fluorine atom and chlorine atom are particularly preferable. These substituents may be substituted at any position on the benzene ring, or the combination of the number and type of the substituents is not limited, but it is usually substituted with 1 to 2 substituents.

Examples of the alkyl group of R include C ₁ -C ₈ such as a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group and an octyl group.
Alkyl groups of As the alkoxyalkyl group, a β-methoxyethyl group, a β-ethoxyethyl group,
β- (n) propoxyethyl group, β- (iso) propoxyethyl group, β- (n) butoxyethyl group, β- (is
o) butoxyethyl group, β- (sec) butoxyethyl group,
β- (n) pentoxyethyl group, β- (n) hexylethyl group, 1-methyl-2-methoxyethyl group, 1-methyl-2-ethoxyethyl group, 3-methoxybutyl group, 3
Examples thereof include an -ethoxybutyl group, a 1-ethyl-2-methoxyethyl group, a 1-ethyl-2-ethoxyethyl group, and a C ₃ -C ₈ β-alkoxyethyl group is particularly preferable. 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.

The method for producing the dye for thermal transfer recording of the present invention, for example, the following general formula [II] (Wherein A is the same as defined above), the compound represented by the following general formula [III] is diazotized by a conventional method. (Wherein B and R are the same as those defined above).

When the above dye is applied to the heat-sensitive transfer sheet of the present invention, an ink is prepared by melting the dye in a medium or dispersing it in fine particles together with a binder, and coating the ink on a base film. A color material layer is formed on the base film by drying.

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 chlorinated solvents, tetrahydrofuran, dioxane and other ethers, N, N'-dimethylformamide, N −
Organic solvents such as methylpyrrolidone may 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, heat resistance is not always sufficient, and thermal head running performance is insufficient. Therefore, it is preferable to improve the running property of the thermal head by providing a layer of a heat-resistant resin containing a surfactant, heat-resistant particles having high lubricity, etc. 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
See "Coating method" issued in 1979).

(Operation and Effect of the Invention) Since the pyrazolone azo type dye for thermal transfer recording represented by the above general formula (I) of the present invention has a vivid yellow color, color reproduction is possible by combining it with an appropriate magenta color and cyan color. It is suitable for obtaining a full-color record having good properties, and is easily sublimated and has a large molecular absorption coefficient, so that a record having a high color density can be obtained at a 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 which is uniformly dissolved or decomposed. 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) Preparation of ink Maximum absorption value λmax: 426 nm (in acetone) Pyrazolone azo dye of the present invention 10 g Cellulose acetate 10 g (L-30, manufactured by Daicel Chemical Industries, Ltd., L-30) Methyl ethyl ketone 80 g Total 100 g A mixture of the above composition is treated with a bain conditioner for 10 minutes Then, the ink was prepared.

b) Preparation of Transfer Sheet The above ink was applied onto a polyethylene terephthalate film (6 μm thick) whose back surface was heat-resistant and slippery coated with a wire bar and 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. 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: Pyraisurf A208B: Daiichi Kogyo Seiyaku Co., Ltd. product); It was performed by 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 Main scanning and sub-scanning linear density: 8 dots / mm Recording power: 0.25 W / dot Head heating time: 10 msec Color density is densitometer RD manufactured by Macbeth, USA
It was measured using a -514 type (filter: Ratten No. 47).

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.

Claims (2)

[Claims] 1. The following general formula (I): (In the formula, A and B represent a lower alkyl group, a lower alkoxy group, a halogen atom, or a benzene ring which may be substituted with a nitro group, and R represents an alkyl group, an alkoxyalkyl group, an allyl group, a cycloalkyl group or A pyrazolone azo type thermal transfer recording dye represented by (representing an aralkyl group). 2. A base film having the following general formula (I): (In the formula, A and B represent a lower alkyl group, a lower alkoxy group, a halogen atom, or a benzene ring which may be substituted with a nitro group, and R represents an alkyl group, an alkoxyalkyl group, an allyl group, a cycloalkyl group or A heat-sensitive transfer sheet having a coloring material layer containing a pyrazolone azo dye represented by (denoting an aralkyl group).