JPH0613642B2 - Dye for heat-sensitive transfer recording and heat-sensitive transfer sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A) Field of Industrial Application The present invention relates to a dye used for sublimation type thermal transfer recording and a thermal transfer sheet using the same. (B) Conventional technology Conventionally, there has been a demand for a facsimile printer, a copying machine, or a technology for color-recording an 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 substrate is heated by a heat-sensitive head to melt the ink, and transfer recording is performed on a recording medium. A transfer sheet on which an ink layer containing a sublimable dye is formed is heated by a thermal head to sublimate the dye,
There is a sublimation method in which transfer recording is performed on the recording medium.However, the sublimation method can control the sublimation transfer amount of the dye by changing the energy applied to the thermal head, which facilitates gradation recording and enables full-color recording. Are considered to be particularly advantageous. C) Problems to be solved by the invention When a dye is applied to this recording system, an ink is prepared by dissolving the dye in a solvent or dispersing it in fine particles together with a binder, and coating the ink on a substrate. Alternatively, it is necessary to prepare a transfer sheet by impregnation (hereinafter simply referred to as coating) and drying. However, if the dye is not completely dissolved in the ink, uneven distribution of the dye occurs on the transfer sheet unless the dye is uniformly dispersed in very fine particles. However, in order to uniformly disperse the fine particles of the dye, a special device and a great deal of labor are required. Also, even in the case of ink in which the dye is completely dissolved,
After coating and drying, the dye often crystallizes on the transfer sheet, causing uneven distribution of the dye. When a transfer sheet having uneven distribution of these dyes is used, color unevenness also occurs in transfer recording, and high-quality recording cannot be obtained. Therefore, in order to obtain a recording without color unevenness, it is necessary to prepare a transfer sheet on which the dye is uniformly applied. For that purpose, it is advantageous that the dye has a high solubility in a solvent, and It is necessary not to crystallize on the sheet after drying.

An object of the present invention is to provide a dye having a large solubility in a solvent and used for sublimation heat transfer recording in which crystals are not formed on a transfer sheet.

Structure of the Invention A) Means for Solving Problems The present invention includes the following general formula [I]. (Wherein R and R ¹ represent different alkyl groups, and the total number of carbon atoms of both is 5 to 8) and a coloring material layer containing the dye on a substrate. A heat-sensitive transfer sheet characterized by having:

The dye of the present invention represented by the general formula [I], by a known method, the following general formula [II] (R and R ¹ are the same as defined above), and can be produced by reacting an aniline with tetracyanoethylene.

Specific examples of the dye of the present invention include dyes represented by the following structural formulas.

(1) (2) (3) (Four) (Five) (6) (7) (8) (9) (Ten) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) As a method for preparing an ink for sublimation heat transfer recording using the dye of the present invention, the dye may be mixed with a binder and a solvent and dissolved. Further, if necessary, inorganic or organic fine particles, anti-blocking agent, defoaming agent, antistatic agent, antioxidant, dispersant, etc. may be added thereto.

Examples of the binder for ink preparation include resins such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone and ethyl cellulose. As a solvent for ink preparation, there are used cellulosolves such as methyl cellosolve and ethyl cellosolve, aromatics such as toluene, xylene and chlorobenzene, esters such as ethyl acetate and butyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone. , Ketones such as microhexanone, chlorine-based solvents such as methylene chloride, chloroform and trichloroethylene, ethers such as tetrahydrofuran and dioxane, N, N-dimethylformamide, N-methylpyrrolidone and the like.

Condenser paper, thin paper such as glassine paper, polyester, polyamide, heat resistant plastic film such as polyimide is suitable as the base film for applying the ink for producing the transfer sheet,
The thickness thereof may be in the range of 3 to 25 μm.

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 amount of the ink deposited is 0.1 to 5 g / m ² after drying. It may be applied so that it is in the range of (Yuji Harasaki, Maki Shoten 1
"Coating method" issued in 979).

Functions and Effects of the Invention The dye represented by the above [I] of the present invention can be said to be a tricyanovinyl dye due to its structure, and since it has a clear magenta color, it can be combined with an appropriate yellow color and cyan color. Therefore, it is suitable for obtaining color records with good color reproducibility, and it is easy to sublimate and has a large molecular extinction coefficient, so high-speed recording with high color density is possible without imposing a heavy burden on the thermal head. Obtainable. Further, since it is stable against heat, light, moisture, chemicals, etc., it is not thermally decomposed during transfer recording, and the storage stability of the obtained record is excellent. Further, since the dye of the present invention has particularly good solubility in a solvent, it is easy to prepare a high-concentration dissolved ink, and since crystallization on the sheet after coating and drying the ink does not occur, It is possible to obtain a transfer sheet having a high concentration and uniformly coated with a dye. Therefore, by using the transfer sheet, it is possible to obtain a recording with good uniformity and color density.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the Examples do not limit the present invention.

Example 1 (a) Preparation of ink The above dyes 10g Polysulfone resin ^* 10g Chlorobenzene 80g Total 100g * Udel (registered trademark) P manufactured by Nissan Chemical Industries, Ltd.
-1700 An ink was prepared by treating the mixture having the above constitution for 10 minutes with a paint conditioner. The dye and resin were completely dissolved, and an ink having a uniform solution could be obtained.

b) Preparation of transfer sheet Apply the above ink to a bar coater (RK Print Coat Instrume
Polyimide film (15μm) using nts NO.1)
(Thickness) and then naturally dried to obtain a transfer sheet.
Even after the ink is dried, the dye does not crystallize on the sheet,
It was possible to obtain a transfer sheet on which the dye was uniformly applied.

(c) Transfer recording The ink-coated surface of the transfer sheet was superposed on the recording medium and recorded using the thermal head under the following conditions to obtain a clear magenta color.
A record with a uniform color density of 1.55 could be obtained.

Recording conditions Linear density in 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 (Toyobo Co., Ltd.). Company manufactured, Bayronal (registered trademark) MP-1200) 10 g and silica (manufactured by Nippon Silica Industry Co., Ltd., Nipsil (registered trademark) E 220A) 1 g
Is prepared by coating a liquid prepared by mixing the above with a high quality paper (200 μm thick) using a bar coater (manufactured by RK Pint Cont Instuments, NO.3) and then drying.

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 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.

The dye used here was obtained by reacting N-ethyl-N- (n) -butylaniline and tetracyanoethylene in N, N-dimethylformamide, and has a melting point of 109- The maximum absorption value of the absorption spectrum of the chloroform solution at 110 ° C. was 527 nm.

Comparative Example 1 Instead of the dye used in Example 1, the following formula was used. An ink was prepared in the same manner as in Example 1 by using the dye represented by No. 2, but the dye was not completely dissolved and an ink having a uniform solution could not be prepared.

Comparative Example 2 Instead of the dye used in Example 1, the following formula was used. In the same manner as in Example 1 using the dye represented by
An ink was prepared and an ink having a uniform solution could be obtained. When a transfer sheet was prepared using this ink in the same manner as in Example 1, needle-like crystals of the dye on the sheet were observed during drying. occured. Example 1 using this transfer sheet
Transfer recording was carried out in the same manner as in 1. However, color unevenness occurred and recording with uniform density could not be obtained.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Nobuyoshi Taguchi 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Akihiro Imai 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A general formula [I] (In the formula, R and R ¹ represent different alkyl groups, and the total carbon number of both is 5 to 8). 2. The dye for thermal transfer recording according to claim 1, wherein R is an ethyl group and R ¹ has 3 carbon atoms.
Dyes represented by alkyl groups of ~ 6. 3. The dye according to claim 2, wherein R ¹ is an n-butyl group. 4. The following general formula [I] is formed on a substrate. (In the formula, R and R ¹ represent different alkyl groups, and the total carbon number of both is 5 to 8.) A heat-sensitive transfer sheet comprising a coloring material layer containing a dye.