JPH0712738B2 - Dicyanoimidazole dye for thermal transfer recording - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A) Field of Industrial Application The present invention relates to a dye used in sublimation thermal transfer recording.

(B) Conventional technology Conventionally, there has been a demand for a technology for colorizing facsimiles, printers, copiers, etc., or for color recording television images, etc., and color recording technology by electrophotography, ink jet, thermal transfer, etc. 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. There is a sublimation method in which a transfer sheet on which an ink layer containing a sublimable dye is formed on a film 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 energy applied to the recording medium, gradation recording becomes easy, which is considered to be particularly advantageous for full-color recording.

C) Problems to be Solved by the Invention When a dye is applied to this recording system, the dye must meet the following conditions.

 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 to synthesize.

 Excellent ink suitability.

An object of the present invention is to provide a magenta dye satisfying all the above conditions.

That is, the present invention has the following general formula [I] (In the formula, R, R ¹ and R ² represent an allyl group, a C _{1 to} C ₈ alkyl group, a C _{3 to} C ₈ alkoxyalkyl group, an aralkyl group and a hydroxyalkyl group, and X represents a methyl group and a methoxy group. , Formylamino group, C ₁ -C ₈ alkylcarbonylamino group, C ₁ -C ₈ alkylsulfonylamino group, C ₁ -C ₈
Which represents a hydrogen atom, a C _{1 to} C ₄ alkoxy group, a methyl group, or a halogen atom), and is a dicyanoimidazole dye for heat-sensitive transfer recording. .

As the method for producing the dye of the present invention, for example, the following structural formula [II] 2-amino-4,5-dicyanoimidazole represented by the following formula is diazotized to give the following general formula [III] (Wherein X, Y, R ¹ and R ² are the same as defined above) and the following general formula [IV] obtained by coupling with an aniline (Wherein X, Y, R ¹ and R ² are the same as defined above), the azo compound represented by the following general formula [V] or [VI] RZ ... [V] (RO) ₂ SO ₂ ... [VI] (in the formula, Z represents a chlorine atom, a bromine atom, an iodine atom, and R is the same as the above definition), and is easily obtained by reacting the alkylating agent.

Specific examples of the dye of the present invention include those shown in Examples, but are not limited thereto.

Particularly preferred are those in the general formula [I].
R, R ¹ and R ² represent an allyl group or a C _{1 to} C ₆ alkyl group, and X
Represents a C ₁ -C ₄ alkylcarbonylamino group, and Y represents a hydrogen atom.

When the dye of the present invention is applied to this recording system, for example, an ink is prepared by dissolving the dye in a medium or dispersing it in a fine particle form together with a binder, and the ink is applied onto a base film, dried and transferred. Sheets can be made.

As a binder for ink preparation, water-soluble resins such as cellulose-based, acrylic acid-based, starch-based, acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone, soluble in organic solvents such as ethyl cellulose Resin etc. can be mentioned. In the case of an organic solvent-soluble resin, it can be used not only as an organic solvent solution but also as an aqueous dispersion.

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, Esters such as butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, methylene chloride, chloroform, chlorinated solvents such as trichloroethylene, ethers such as tetrahydrofuran and dioxane, N, N-dimethylformamide, N- Organic solvents such as methylpyrrolidone may be mentioned.

As the base film for applying the ink for producing the transfer sheet, condenser paper, thin paper such as glassine paper, polyester, polyamide, and heat resistant plastic film such as polyimide are suitable,
The thickness thereof may 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. So that it can be applied (Yuji Harasaki, Maki Shoten 1979
Issued annually "Coating method").

ACTION AND EFFECTS OF THE INVENTION The dicyanoimidazole dye of the present invention [I] has a vivid magenta color, and therefore, by combining with an appropriate yellow color and cyan color, a full color recording with good color reproducibility is obtained. In addition, since it is easy to sublimate and has a large molecular extinction coefficient, it is possible to obtain a high-speed recording with a high color density without imposing a heavy burden on the thermal head. Further, since it is stable against heat, light, moisture, chemicals, etc., it is not thermally decomposed during transfer recording and the obtained record is excellent in storability. Further, since the dye of the present invention 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, and by using these inks, It is possible to obtain a transfer sheet on which the dye is uniformly applied in high concentration. Therefore, by using these transfer sheets, it is possible to obtain a recording with good uniformity and color density.

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 above-mentioned dicyanoimidazole dye of the present invention 10 g Cellulose acetate (L-30, manufactured by Daicel Chemical Industries, Ltd.) 10 g Methyl ethyl ketone 80 g Total 100 g The mixture having the above composition was treated with a paint conditioner for 10 minutes to prepare an ink. . The dye and the resin are completely dissolved, and an ink having a uniform solution can be obtained.

b) Preparation of transfer sheet The above ink was applied to a bar coater (RK Print Coat Instrume
nts No.1) is used for polyimide film (15μm)
(Thickness) and then naturally dried to obtain a transfer sheet.

c) Transfer recording The ink-coated surface of the transfer sheet was superposed on the recording medium and a thermal head was used for recording under the following conditions to obtain a clear magenta color for 1.20.
It is possible to obtain a uniform color density record.

Recording conditions Linear density for main scanning and sub scanning: 4 dots / mm Recording power: 0.6 W / dot Heating time for head: 10 msec The recording medium is an aqueous dispersion of 34 wt% saturated polyester (manufactured by Toyobo Co., Ltd.). , Bayronal MD-1200,
Product name) 10g and silica (Nippon Silica Industry Co., Ltd., N
ipsil E220A, trade name) 1g was mixed and prepared on a fine paper (200μm thick) bar coater (RK Print Coat Instrum
No.3) manufactured by ents, Inc. is applied and then dried.

Color density is densitometer RD- manufactured by Macbeth, USA
It was measured using a 514 type (filter: Ratten No. 58).

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 magenta 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.

Example 3 Using the dicyanoimidazole dye of the present invention used in Example 1, the following composition dye 10 g ethyl cellulose (manufactured by Herquiures) 10 g methyl ethyl ketone 80 g A total of 100 g was used to prepare the ink, and As a result of making a transfer sheet and performing transfer recording by the same method, it was possible to obtain a record having excellent storage stability and light fastness with a clear magenta color density of 1.20.

Claims (3)

[Claims] 1. A general formula [I] (In the formula, R, R ¹ and R ² are allyl groups, C _{1 to} C ₈ alkyl groups,
Alkoxyalkyl groups C ₃ -C _8, aralkyl group, a hydroxyalkyl group, X is a methyl group, a methoxy group,
Formylamino group, C ₁ -C ₈ alkylcarbonylamino group, C ₁ -C ₈ alkylsulfonylamino group, C ₁ -C ₈ alkoxycarbonylamino group, and Y represents a hydrogen atom, C ₁ -C ₄ Represents an alkoxy group, a methyl group, or a halogen atom), and is a dicyanoimidazole dye for thermal transfer recording. 2. The dicyanoimidazole dye for heat-sensitive transfer recording according to claim 1, which is used in a heat-sensitive transfer sheet having a colorant layer containing a binder and a dye on a base material. 3. The dicyanoimidazole dye for thermal transfer recording according to claim 1, wherein R, R ¹ and R ² represent an allyl group or a C ₁ -C ₆ alkyl group, and X represents C ₁ To C ₄ alkylcarbonylamino group, and Y represents a hydrogen atom.