JPH0515197B2 - - Google Patents

Description

[Detailed description of the invention]

Object of the Invention (a) Industrial Application Field The present invention relates to a dye used in sublimation type thermal transfer recording. (b) Prior Art Conventionally, there has been a demand for technology for color recording facsimile printers, copying machines, television images, etc., and color recording technologies using electrophotography, inkjet, thermal transfer, etc. are being considered. The thermal transfer recording method is considered to be advantageous over other methods because the device is easy to maintain and operate, and the device and consumables are inexpensive. Thermal transfer methods include a melting method in which a transfer sheet with a heat-melting ink layer formed on a base film is heated by a heat-sensitive head to melt the ink and transfer recording onto 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 then transferred and recorded onto a recording medium. Since the amount of sublimation transfer of the dye can be controlled by changing the applied energy, gradation recording becomes easy and is considered to be particularly advantageous for full color recording. (c) Problems to be Solved by the Invention The transfer sheet used for the above purpose is required to be able to perform high density and uniform transfer recording and to have good abrasion resistance. In other words, if the image is not transferred uniformly, density unevenness will occur in the image, and if the abrasion resistance is poor, excess dye will develop in areas other than the image area that are not recorded, resulting in the so-called background smearing phenomenon. This is because the overall quality will deteriorate. These scumming phenomena occur because the dye recrystallizes when it is dissolved or dried, forming coarse crystals, or because the dye does not dissolve completely and remains as coarse crystals. it is conceivable that. Structure of the invention (a) Means for solving the problem That is, the present invention solves the following general formula [] (In the formula, R represents a _C2 to _C10 alkyl group, a _C2 to _C10 alkoxy group, or a trifluoromethyl group.) As a method for producing these anthraquinone dyes of the present invention, for example, the following structural formula [] The compound represented by and the following general formula [] (In the formula, R is the same as defined above.) It can be obtained by heating a phenol represented by the following in a polar solvent in the presence of a deoxidizing agent. Particularly preferred is the general formula []
Examples include dyes in which R is a _C2 to _C10 alkyl group or a _C2 to _C6 alkoxy group. When applying the dye of the present invention to this recording method, it is necessary to prepare an ink by dissolving the dye together with a binder in a medium, apply the ink onto a base film, and dry it to prepare a transfer sheet. . Binders for ink preparation include water-soluble resins such as cellulose, acrylic acid, and starch, and organic solvent-soluble resins such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyethersulfone, and ethyl cellulose. Examples include resin. Vehicles for ink preparation include toluene,
Aromatics such as xylene and chlorobenzene, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, chlorinated solvents such as methylene chloride, chloroform, and trichloroethylene, tetrahydrofuran, dioxane, etc. Examples include organic solvents such as ethers, N,N-dimethylformamide, and N-methylpyrrolidone. The base film used to apply ink for the production of transfer sheets includes condenser paper, thin paper such as glassine paper, polyester, polyamide,
Plastic films with good heat resistance such as polyimide are suitable, and their thickness may range from 3 to 50 .mu.m. The ink can be applied to the base film using a reverse roll coater, gravure coater, rod coater, air doctor coater, etc., and the thickness of the ink coating layer after drying is in the range of 0.1 to 5 μm. All you have to do is apply it so that it is coated ("Coating Method" by Yuji Harasaki, published by Maki Shoten in 1979). Functions and Effects of the Invention The anthraquinone dye shown in [] above of the present invention has a clear magenta color, so it is possible to obtain full-color recording with good color reproducibility by combining it with appropriate yellow and cyan colors. suitable for In particular, since it is stable against heat, light, moisture, chemicals, etc., it does not undergo thermal decomposition during transfer recording, and the resulting recording has excellent storage stability. In addition, since the dye of the present invention has particularly good solubility in organic solvents and binders, it is easy to prepare uniformly dissolved and highly concentrated inks, and these inks can be used. By doing so, it is possible to obtain a transfer sheet having excellent abrasion resistance and fastness to which the dye is applied uniformly and at a high concentration.
Therefore, by using these transfer sheets, it is possible to obtain excellent recording without image unevenness and background smudge. EXAMPLES The present invention will be specifically explained below with reference to Examples, but these Examples are not intended to limit the present invention. Example 1 (a) Preparation of ink Anthraquinone dye used in this example: Above dye 10g Cellulose acetate (manufactured by Daicel Chemical Co., Ltd., L-30)
10g Methyl ethyl ketone 80g Total 100g The mixture having the above composition was treated with a paint conditioner for 10 minutes to prepare an ink.
The pigment and resin were completely dissolved, and an ink with a uniform solution could be obtained. (b) Preparation of transfer sheet Apply the above ink using a bar coater (RK Print).
Coat Instruments Co., Ltd. No. 1) was applied onto a capacitor paper (10 μm thick) and then air-dried to obtain a transfer sheet. The resulting transfer sheet was uniform and had excellent abrasion resistance. (c) Transfer recording The ink-coated surface of the above transfer sheet was placed over the recording medium and recorded using a thermal head under the following conditions, and a clear magenta color with a color density of 1.15 was obtained, with a good transfer record without unevenness and background stains. I was able to get Recording conditions Linear density of main scanning and sub-scanning: 4 dots/mm Recording power: 0.6 W/Dot head heating time: 10 msec The recording medium was an aqueous dispersion of 34% by weight saturated polyester (manufactured by Toyobo Co., Ltd., Vylonal MD-1200, trade name) 10g and silica (manufactured by Nippon Silica Kogyo Co., Ltd., Nipsil E220A,
Mix 1 g of product name) and apply the prepared solution to high-quality paper (200 μm thick) using a bar coater (RK Print Coat).
After application using No. 3 manufactured by Instruments,
It is manufactured by drying. Color density was measured using a densitometer RD-514 model manufactured by Macbeth Corporation in the United States (filter: Ratten No.
58). The light resistance test of the obtained record was performed using a carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.).
(Black panel temperature 63±2℃)
However, there was almost no discoloration or fading after 40 hours of irradiation. Furthermore, the transfer sheet and the recording were stable against heat and moisture, and had excellent storage stability in the dark. Example 2 Instead of the dyes used in Example 1, the dyes shown in Table 1 were used to prepare ink, prepare a transfer sheet, and perform transfer recording in the same manner as in Example 1. As a result, the results shown in Table 1 were obtained. It was possible to obtain a good transfer record of a clear magenta color image with a clear color density as shown in FIG. The results of the light fastness test of the obtained record and the dark storage stability test of the transfer sheet and record were good.

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[Table] Example 3 Using the anthraquinone pigment of the present invention used in Example 1, an ink was prepared with the following composition pigment (same as in Example 1): 10 g Ethyl cellulose (manufactured by Hercules) 10 g Methyl ethyl ketone 80 g Total 100 g A transfer sheet was prepared and transfer recording was performed in the same manner as in Example 1, except for the following steps. As a result, a clear magenta image with a color density of 1.15 was produced, with no unevenness, and a good transfer record without background stains. I was able to get Lightfastness test of the obtained recording and transfer sheet
The results of the dark storage stability test of the records were good. Comparative Example 1 The following structural formula was used instead of the anthraquinone dye of the present invention used in Example 1. When an ink was prepared using the dye shown in Example 1 in the same manner as in Example 1, the dye was not completely dissolved in the solvent, and some of the dye remained as coarse crystals. When the above ink was applied in the same manner as in Example 1, recrystallization also occurred during drying.
A non-uniform transfer sheet was obtained in which coarse crystals were precipitated here and there. When transfer recording was carried out using the above transfer sheet in the same manner as in Example 1, an uneven transfer record with uneven images was obtained, and additionally, the unrecorded areas were also colored by excess dye. occurred, reducing the overall quality of the image.

Claims (1)

[Claims] 1. General formula [] (In the formula, R represents a _C2 - _C10 alkyl group, a _C2 - _C10 alkoxy group, or a trifluoromethyl group.) An anthraquinone dye for thermal transfer recording. 2. An anthraquinone dye for thermal transfer recording according to claim 1, which is used in a thermal transfer sheet having a coloring material layer containing a binder and a dye on a base material.