JPH0515199B2 - - 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. The thermal transfer method is a melting method in which a transfer sheet with a heat-melting ink layer formed on a base film is heated with a heat-sensitive head or a laser to melt the ink and transfer it onto a recording medium. There is a sublimation method, in which a transfer sheet in which an ink layer containing a sublimable dye is formed on a base film is heated with a heat-sensitive head or a laser to sublimate the dye, and then transferred and recorded onto a recording medium. This method can control the amount of dye sublimation transfer by changing the energy to a heat source such as a thermal head or a laser, which facilitates gradation recording and is considered 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 phenomena may be due to the dye dissolving and recrystallizing when drying to form coarse crystals.
Alternatively, it is thought that this occurs because the dyes are not completely dissolved and remain as coarse crystals.In order to solve these problems, we have conducted extensive studies on the dyes used in this recording method, and found that the density unevenness in the images has been It has now become possible to provide a yellow dye from which a transfer sheet with good abrasion resistance and fastness can be obtained. That is, the present invention provides the following general formula [] (In the formula,

[Formula] may be substituted with a _C1-12 alkyl group, a _C1-12 alkoxy group, _a chlorine atom, a bromine atom, an iodine atom, a nitro group, a cyano group, or _{a C1-12 alkoxycarbonyl} group. The gist of the _invention is a pyridone azo dye for thermal transfer recording, represented by a phenyl group, and R represents a _C5-12 linear or branched alkyl group. As a method for producing these dyes of the present invention, for example, the following structural formula [] (In the formula,

[Formula] is the same as the above definition) is diazotized by the usual method, and the following general formula [] (In the formula, R is the same as defined above.) It can be obtained by coupling with a compound represented by the following. 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 aqueous resins such as cellulose, acrylic acid, and starch, and resins soluble in organic solvents such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyethersulfone, and ethyl cellulose. etc. can be mentioned. Media for ink preparation include aromatics such as toluene, xylene, and chlorobenzene, esters such as ethyl acetate and butyl acetate, acetone,
Methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as cyclohexanone, chlorinated solvents such as methylene chloride, chloroform, and trichloroethylene, ethers such as tetrahydrofuran and dioxane, N,N-dimethylformamide,
Organic solvents such as N-methylpyrrolidone may be mentioned. The paste 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, graphia 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). Examples of the heat source that provides energy include a thermal head or a laser. In the case of a thermal head, the applied energy can be varied by varying the applied voltage or pulse width. In the case of laser light, the energy provided can be changed by changing the output of the light source or the width of the light pulse. Functions and Effects of the Invention The pyridone azo dye shown in the above [] of the present invention has a clear yellow color, so it can be used in combination with appropriate magenta and cyan colors to obtain full-color recording with good color reproducibility. Are suitable. 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 good solubility in binding properties, 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 records without image unevenness and background smear. 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 The above pigment: 10 g Cellulose acetate: 10 g (Daicel Chemical Co., Ltd., L-30) 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 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).
The transfer sheet was coated on a capacitor paper (10 μm thick) using Coat Instruments Co., Ltd. No. 1) and air-dried to obtain a uniform transfer sheet with excellent abrasion resistance and fastness. (c) Transfer recording The ink-applied surface of the above transfer sheet was placed on the recording medium and recorded using a thermal head under the following conditions, resulting in a clear yellow color with a color density of 0.80, an even image, and a good transfer with no background stains. I was able to obtain the record. Recording conditions Main scanning and sub-scanning linear density: 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 (filter: Ratten No. manufactured by McPeth, USA).
47). A light resistance test of the obtained recording was carried out using a carbon arc fade meter (manufactured by Suga Testimonials Co., Ltd.) (black panel temperature: 63±2° C.), and 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 Ink was prepared in the same manner as in Example 1 using the colors shown in Table 1 instead of the pigments used in Example 1.
As a result of preparing the transfer sheet and performing transfer recording,
It was possible to obtain good transfer records with clear yellow images having the color densities shown in Table 1 without unevenness and with no scumming. Lightfastness test of the obtained recording and transfer sheet
The results of the dark storage stability test of the records were good.

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Claims (1)

[Claims] 1. General formula [] (In the formula, [Formula] is substituted with a C ₁ to ₁₂ alkyl group, a C ₁ to ₁₂ alkoxy group, a chlorine atom, a bromine atom, an iodine atom, a nitro group, a cyano group, or a C ₁ to ₁₂ alkoxycarbonyl group) and R represents a _C5-12 linear or branched alkyl group _. 2. A pyridone azo dye for thermal transfer recording according to claim 1, which is used in a thermal transfer sheet comprising a color material layer containing a binder and a dye provided on a base material.