JPH0485081A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To enhance the color purity of a cyane dye and to obtain a recording article having good color reproducibility by providing a colorant layer containing a thermal transfer cyan dye, a thermal transfer compound emitting fluorescence and a resin as a binder on a base film. CONSTITUTION:A colorant layer containing a thermal transfer cyan dye, a thermal transfer compound emitting fluorescence within the range of 400-600nm and a resin as a binder is provided on a base film and the thermal transfer compound contains at least a fluorescent brightener and a fluorescent dye. By using the thermal transfer compound along with the thermal transfer cyan dye, the unnecessary absorption of the cyan dye in a transfer recording article within the region of 400-600nm is removed or reduced by the fluorescent compounds and a cyan color having good color purity can be obtained and, therefore, the color reproducibility of the recording article can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal transfer sheet used for thermal transfer recording, particularly for sublimation type thermal transfer recording.

(Prior Art) Conventionally, color recording technologies using electrophotography, inkjet, thermal transfer, and the like have been studied for facsimiles, copying machines, printers, and the like.

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 includes a melting method in which a transfer sheet with a heat-fusible ink layer formed on a base film is heated by a thermal head to melt the ink and transfer and record the ink image onto a receiver; Sublimation: A transfer sheet on which a color material layer containing a heat-transferable dye is formed on a base film is heated by a thermal head to transfer the dye from the transfer sheet to an image receptor, and transfer and record the dye image onto the image receptor. However, the sublimation method can control the amount of dye transfer by changing the energy applied to the thermal head, making gradation recording easy and particularly advantageous for full-color recording.

(Problem to be Solved by the Invention) By the way, in sublimation type thermal transfer recording, in order to perform full color recording, heat transferable yellow, magenta,
Three primary color pigments of cyan are required, and in order to obtain a recorded matter with good color reproducibility, each of the three primary color pigments must have good color purity.

In general, cyan dyes have their original absorption range (600-700
In addition to 400 to 600 nm, the color purity decreases due to unnecessary absorption in the range of 400 to 600 nm.

The present invention provides a heat-sensitive transfer sheet that improves the color purity of cyan dyes by removing or reducing unnecessary absorption in the 400 to 600 nm region of cyan dyes, and is capable of obtaining recorded materials with good color reproducibility. The purpose is to provide the following.

(Means for Solving the Problems) The present invention provides a base film containing a heat-transferable cyan dye, a heat-transferable compound that emits fluorescence in the range of 400 to 600 nw, and a resin as a binder. It has a material layer,
The gist of the present invention is a thermal transfer sheet characterized in that the heat-transferable compound that emits fluorescence contains at least a fluorescent whitening agent and a fluorescent dye.

In the present invention, along with a heat-transferable cyan dye, 40
By using a heat-transferable compound that emits fluorescence in the range of 0 to 600 nm, the cyan dye in the transfer record can be
Unnecessary absorption in the region of 0 to 600 nm can be removed or reduced by the fluorescent compound, making it possible to obtain a cyan color with good color purity and improving the color reproducibility of recorded materials.

The present invention will be explained in detail below.

The heat-transferable cyan dye used in the present invention includes:
Known anthraquinone series, azo series, azomethine series, indoaniline series, which have already been proposed for heat-sensitive transfer sheets.
Dyes such as naphthoquinone can be used.

Compounds that emit fluorescence in the range of 400 to 600 nm used in the present invention include fluorescent whitening agents and fluorescent dyes. Fluorescent brighteners generally have an absorption maximum value below 400 nmw and emit fluorescence in the range of 400 to 500 nI11, but when only a fluorescent brightener is used,
This is not sufficient because unnecessary absorption in the 600 nm range cannot be removed. Therefore, in order to eliminate unnecessary absorption in the range of 500 to 600 n-, it is necessary to use a fluorescent dye that emits fluorescence in this range. However, since such fluorescent dyes generally have absorption in the range of 400 to 500 nm, when used alone, the color purity is reduced due to these absorptions. This decrease in color purity caused by fluorescent dyes can be improved by adding a fluorescent whitening agent. Therefore, 400 to 60 of cyan dye
In order to eliminate unnecessary absorption of On-, it is desirable to use a thermal transferable fluorescent whitening agent and a fluorescent dye in combination.

Examples of optical brighteners used here include stilbene-based, benzoxazole-based, benzotriazole-based, coumarin-based, and naphthalene-based brighteners, which are mainly used for brightening polyester fibers and resins. Water-insoluble materials such as acid imide, thiophene, oxazole, triazole, benzofuran, and pyrazoline are suitable.

Among these, benzoxazole-based, coumarin-based, and nabutanoic acid imide-based ones are particularly suitable in terms of fluorescence ability and light resistance. In addition, similar to fluorescent brighteners, water-insoluble fluorescent dyes used for dyeing polyester fibers and coloring resins are used as fluorescent dyes, and structurally,
Fluorescent yellow and orange dyes such as naphthalimide, perinone, coumarin, and lactone dyes are particularly suitable.

The amounts of the fluorescent whitening agent and fluorescent dye used here are such that unnecessary absorption in the range of 400 to 600 n- is removed by the cyan dye, and the amount of the fluorescent whitening agent used is determined to remove unnecessary absorption in the range of 400 to 600 n-. The amount required to remove the absorption of cyan dyes, the intensity of fluorescence of fluorescent whitening agents and fluorescent dyes, the amount of absorption of fluorescent dyes in the visible range,
The amount of the fluorescent brightener is 5 to 200% by weight, preferably 10 to 100% by weight, based on the cyan dye, although it varies depending on the cyan dye, the fluorescent whitening agent, and the transferability of the fluorescent dye.
The weight % range is 1 for the fluorescent dye relative to the cyan dye.
A range of from 100% by weight, preferably from 5 to 50% by weight, is suitable.

When forming a color material layer containing the above-mentioned cyan dye, fluorescent whitening agent, and fluorescent dye in the thermal transfer sheet of the present invention,
The method is not particularly limited; usually, an ink is prepared by dissolving or dispersing a pigment, a fluorescent whitening agent, and a fluorescent pigment in a medium together with a binder in the form of fine particles, and the ink is spread on a base film. A coloring material layer is formed on the base film by coating and drying.

As a binder for ink preparation, a binder with good heat resistance is used to prevent heat fusion with the image receptor during transfer recording, but in particular binders with a softening point and/or heat distortion temperature of 100°C or higher preferable.

Specifically, water-soluble resins such as cellulose, acrylic acid, and starch, acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, AS resin, polyether sulfone, polyvinyl butyral, polyester, ethyl cellulose, acetyl cellulose, and phenoxy resin. Examples include organic solvents such as or water-soluble resins.

These resins may be selected as appropriate depending on the solvent used as a medium for preparing the ink, and any resin that can be dissolved or uniformly dispersed in the solvent may be used.

The amount of these resins used is in the range of 1 to 30% by weight, preferably 5 to 20% by weight based on the total weight of the ink composition. The amount of cyan pigment used is 1 to 20% by weight, preferably 3 to 20% by weight based on the total weight of the ink composition.
15% by weight, and the amount of the optical brightener used is 0.05 to 40% by weight, preferably 0.05% to 40% by weight based on the total weight of the ink composition.
．． The amount of fluorescent dye used is 0.01 to 20% by weight, preferably 0.01 to 20% by weight, based on the total weight of the ink composition.
05 to 10% by weight.

In addition to water, media for ink preparation include alcohols such as methyl alcohol, isopropyl alcohol, and isobutyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, aromatics such as toluene, xylene, and chlorobenzene, ethyl acetate, Esters such as butyl acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, chlorinated solvents such as methylene chloride, chloroform, and trichloroethylene, ethers such as tetrahydrofuran and dioxane, N, N-dimethylformamide, N- Examples include organic solvents such as methylpyrrolidone, which may be used alone or in combination.

In addition to the above ingredients, the above ink also contains organic and inorganic non-sublimable fine particles, dispersants, antistatic agents, antiblocking agents, antifoaming agents, antioxidants, viscosity modifiers, and mold release agents. Agents etc. can be added.

Suitable base films for applying ink for making transfer sheets include thin paper such as condenser paper and glassine paper, and plastic films with good heat resistance such as polyester, polycarbonate, polyamide, polyimide, and polyaramid. , their thickness can range from 3 to 50 μm.

Among the above base films, polyethylene terephthalate film is particularly advantageous in view of mechanical strength, solvent resistance, economic efficiency, and the like. However, in some cases, polyethylene terephthalate film does not necessarily have sufficient heat resistance, and the running properties of the thermal head are insufficient. By providing a layer of synthetic resin, it is possible to use a thermal head with improved running performance.

The ink can be applied to the base film using a reverse roll coater, gravure coater rod coater, air doctor coater, etc. The thickness of the ink coating layer after drying is 0.1 to 5 μm. (Yuji Harasaki, Yuji, Shoten 1)
``Coating method'' published in 1979).

The heat-sensitive transfer sheet of the present invention can utilize not only a thermal head but also infrared rays, laser light, etc. as a heating means.

Furthermore, the ink composition of the present invention can be applied onto an electrically conductive film that generates heat by 3RN, and used as an electrically conductive thermal transfer sheet.

In order to obtain full-color recording, a thermal transfer sheet is usually used in which coating areas are sequentially provided in the three primary colors of yellow, magenta and cyan, or in four colors, including black. It is preferable to use a heat-sensitive transfer sheet having a coloring material layer, which is a feature of the present invention, for these cyan coated areas, since a clear full-color image can be obtained.

(Operations and Effects of the Invention) The heat-sensitive transfer sheet of the present invention includes a heat-transferable cyan dye,
By using a heat-transferable compound that emits fluorescence in the range of 400 to 600 nm, such as a fluorescent whitening agent or fluorescent dye, the cyan dye in the transfer record can be removed from 400 to 600 nm.
By removing or reducing unnecessary absorption in the recording medium and improving the color purity of cyan, it is possible to provide recorded matter with good color reproducibility.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples, but these Examples do not limit the present invention.

Example 1 a) Preparation of ink Use cyan dye Use fluorescent brightener Use fluorescent dye Coat on a film (6 μm thick) and dry to a dry film thickness of 1 μm
m), a transfer sheet was obtained. In addition, the heat-resistant lubricity treatment of polyethylene terephthalate film is carried out on polyethylene terephthalate film using the following formula ink composition: 5 g of the above cyan dye 4 g of the above fluorescent brightener 0.5 g of the above fluorescent dye 10 g of polysulfone resin
100g total 119.
5g Product name Newdel P-1700 (Nissan Chemical Industry ■
Product) Heat distortion temperature (ASTMD-6 48) 175°C A mixture having the above composition was treated with a paint conditioner for 10 minutes to prepare an ink.

b) Preparation of transfer sheet 8 parts by weight of a polycarbonate resin having a repeating structural unit represented by a polyethylene terephthalate sheet whose back surface is heat-resistant and slippery treated by applying the above ink using a wire bar;
By applying a solution consisting of 1 part by weight of a phosphate ester surfactant (trade name: Niblysurf A-208B, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 91 parts by weight of toluene, and drying (0.5 μm in dry film thickness). I did it.

C) Creation of image receptor 10 parts of saturated polyester resin (product name: TP-220, product of Nippon Gosei Co., Ltd.), 0.5 parts of amino-modified silicone (product name: KF393, product of Shin-Etsu Chemical Co., Ltd.)
15 parts of methyl ethyl ketone, and 15 parts of xylene was applied onto synthetic paper (product name: Yubo FPG150, manufactured by Oji Yuka Co., Ltd.) with a wire bar, dried (dry film thickness approximately 5 μm), and further heated in an oven for 100 minutes. An image receptor was prepared by heat treatment at C for 30 minutes.

d) Transfer Recording The ink coated surface of the above transfer sheet was overlapped with the recording medium and recording was performed using a thermal head under the following conditions, and a very clear cyan-colored transfer record could be obtained.

Recording conditions Main scanning and sub-scanning density: 8 dots/! Heating time of ll111 recording electric crab 0.25W/dot head: 1 (1+sec) Comparative Example 1 Ink was prepared in the same manner as in Example 1, except that the fluorescent brightener and fluorescent dye were not used. As a result of preparing a transfer sheet and carrying out transfer recording, the obtained transfer record had a greenish cyan color.

Comparative Example 2 The ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 1, except that the fluorescent dye was not used. As a result, the obtained transfer record was clear. Although the color was cyan, it was slightly reddish and inferior to that of Example 1.

Example 2 In place of the fluorescent brightener used in Example 1, 3 g of a fluorescent brightener represented by the following formula was used, and the other steps were the same as in Example 1, ink preparation, transfer sheet production, and transfer recording. As a result, a very clear cyan-colored transfer record could be obtained.

Example 3 In place of the fluorescent brightener used in Example 1, 2 g of a fluorescent brightener represented by the following formula was used, and the other steps were the same as in Example 1, such as ink preparation, transfer sheet production, and transfer recording. As a result, a very clear cyan-colored transfer record could be obtained.

Example 4 In place of the fluorescent brightener used in Example 1, 1.5 g of a fluorescent brightener represented by the following formula was used, and the other procedures were the same as in Example 1, such as preparing ink, producing a transfer sheet, As a result of the transfer recording, a very clear cyan-colored transfer record could be obtained.

Example 6 In place of the cyan dye used in Example 1, 2 g of a fluorescent whitening agent represented by the following formula was used, and ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 1. As a result, a very clear cyan-colored transfer record could be obtained.

Example 5 In place of the fluorescent brightener used in Example 1, 5 g of cyan dye represented by the following formula was used, and ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 1. As a result, a very clear cyan-colored transfer record could be obtained.

Comparative Example 3 In Example 6, the ink was prepared, the transfer sheet was prepared, and the transfer recording was performed in the same manner as in Example 6, without using the fluorescent whitening agent and the fluorescent dye. The transferred recording material had a greenish cyan color.

Comparative Example 4 In Example 6, the ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 6, without using the fluorescent dye. As a result, the obtained transfer record was clear. Although the color was cyan, it had a slight reddish tinge and was inferior to that of Example 6.

Example 7 Ink preparation, transfer sheet production, and transfer recording were performed in the same manner as in Example 1, except that 7 g of cyan dye represented by the following formula was used instead of the cyan dye used in Example 1. , a very clear cyan-colored transfer record could be obtained.

Comparative Example 5 In Example 7, the ink was prepared, the transfer sheet was prepared, and the transfer recording was performed in the same manner as in Example 7, without using the fluorescent whitening agent and the fluorescent dye. The transferred record was a cyan color with a dark line tinge.

Comparative Example 6 In Example 7, the ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 7, without using the fluorescent dye. As a result, the obtained transfer record was slightly different. It had a reddish cyan color and was inferior to that of Example 7.

Example 8 In the following formula Example 8, instead of the cyan dye used in Example 1, the ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 8, except that no fluorescent dye was used. As a result, the resulting transferred recorded matter had a reddish cyan color.

Example 9 Ink preparation, transfer sheet production, and transfer recording were performed in the same manner as in Example 1 except that 5 g of cyan dye represented by the following formula was used instead of the fluorescent dye used in Example 1. , a very clear cyan-colored transfer record could be obtained.

Comparative Example 7 In Example 8, the ink was prepared, the transfer sheet was prepared, and the transfer recording was performed in the same manner as in Example 8, without using the fluorescent whitening agent and the fluorescent dye. The transferred record was a cyan color with a dark line tinge.

Using 0.5g of a lactone-based fluorescent dye represented by
Otherwise, ink preparation, transfer sheet production, and transfer recording were carried out in the same manner as in Example 1, and as a result, a very clear cyan-colored transfer record could be obtained.

Example 10 Using the following formula instead of the fluorescent dye used in Example 1, a bright cyan-colored transfer record could be obtained.

The ink was prepared, the transfer sheet was prepared, and the transfer recording was performed in the same manner as in Example 1 except for using 1.0 g of the naratarimide fluorescent dye represented by I was able to get things.

Example 11

Claims (2)

[Claims] (1) Heat-transferable cyan dye on the base film,
It has a coloring material layer containing a heat-transferable compound that emits fluorescence in the range of 400 to 600 nm and a resin as a binder, and the heat-transferable compound that emits fluorescence is at least combined with an optical brightener and a fluorescent material. A heat-sensitive transfer sheet characterized by containing a pigment. (2) In a heat-sensitive transfer sheet having a coating area of three colors: yellow, magenta, and cyan, or four colors including black, the cyan coating area is a heat-transferable cyan pigment on the base film. , a heat-sensitive transfer sheet comprising a coloring material layer containing a heat-transferable compound that emits fluorescence in the range of 400 to 600 nm and a resin as a binder.