JPH03230994A - Heat-sensitive transfer sheet and ink composition for heat-sensitive transfer sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

(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.

Thermal transfer methods include 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 then transferred and recorded onto an image receptor; A transfer sheet on which a color material layer containing a sublimable dye is formed is heated with a thermal head, and the dye is transferred from the transfer sheet to an image receptor by sublimation and/or thermal diffusion, and is transferred and recorded on 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.

In thermal transfer recording using the sublimation method, the sublimable dye used in the transfer sheet and the ink composition for the transfer sheet is extremely important as it has a significant impact on the speed of transfer recording, the image quality of the recorded material, and the storage stability. Yes, the following conditions must be met.

■ Easily sublimated and/or thermally diffused under the operating conditions of the thermal recording head.

■Do not thermally decompose under the operating conditions of the thermal recording head.

■ It must have a favorable hue in terms of color reproduction.

■ High molecular extinction coefficient.

■ Stable against heat, light, moisture, chemicals, etc.

■ Easy to synthesize.

■ Excellent suitability for ink production.

■ No safety and health problems.

Up to now, no dye has been found that satisfies all of the above conditions, and yellow dyes in particular have various drawbacks and have not yet been found to be satisfactory.

As a yellow dye, it has been reported in JP-A-51-7889 that a styryl dye having the same basic skeleton as used in the present invention is excellent as a dye for sublimation type thermal transfer recording.
No. 5, JP-A-60-28451, JP-A-60-284
This is shown in issues such as No. 53. However, the dyes shown there still did not have sufficient performance, particularly in terms of photostability (light resistance).

Therefore, the inventors conducted a more detailed study on styryl dyes, and found that by creating a specific structure as shown in general formula (1), the photostability (light resistance) was improved.
The present invention was achieved by discovering a styryl dye that exhibits good performance in other properties as well.

(Problems to be Solved by the Invention) An object of the present invention is to provide a thermal transfer sheet and an ink composition for a thermal transfer sheet, which are characterized by using a yellow dye that satisfies all of the above conditions.

(Means for Solving the Problems) The present invention relates to a binder and the following general formula (1) (wherein R1 and R2 are a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an allyl group, or a substituted or Represents an unsubstituted phenyl group, X and Y represent a hydrogen atom, a halogen atom, a lower alkyl group, or a lower alkoxy group, and includes a styryl dye represented by the following: (at least one of X and Y represents a lower alkoxy group) A heat-sensitive transfer sheet characterized by having a coloring material layer, and an ink for a heat-sensitive transfer sheet containing a styryl dye, a resin as a binder, and an organic solvent and/or water. The gist is the composition.

The present invention will be explained in detail below.

The styryl dye represented by the general formula (1) used in the present invention can be produced according to a conventionally known method. For example, malononitrile is expressed by the following general formula (II) and Y represents the same meaning as in general formula (I)) in water or an organic solvent.

To specifically explain the dye represented by the general formula (1) used in the present invention, in the formula, the unsubstituted alkyl group represented by R1 and R2 is a linear or branched chain of 01 to C8. Substituted alkyl groups include hydroxy-substituted alkyl groups such as 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, and 2-hydroxypropyl group; carboxymethyl group, 2-carboxy Carboxy-substituted alkyl groups such as ethyl group and 3-carboxypropyl group; Cyano-substituted alkyl groups such as 2-cyanoethyl group and cyanomethyl group; Amino-substituted alkyl groups such as 2-aminoethyl group; 2
- Halogen-substituted alkyl groups such as chloroethyl group, 3-chloropropyl group, 2-chloropropyl group, 2.2.2-)lifluoroethyl group; benzyl group, p-chlorobenzyl group, 2-phenylethyl group, etc. optionally substituted phenyl-substituted alkyl group; 2-methoxyethyl group, 2-ethoxyethyl group, 2(n) propoxyethyl group, 2-(iso)propoxyethyl group, 2-(n) butoxyethyl group, 2-(iso)butoxyethyl group, 2
-(2-ethylhexyloxy)ethyl group, 3-methoxypropyl group, 4-methoxybutyl group, 2-methoxy(
2-methoxyethoxy)ethyl group, 2-(2ethoxyethoxy)ethyl group, 2-(2m-(n)propoxyethoxy)ethyl group, 2-(2-(iSO)propoxyethoxy)ethyl group, 2-(2 Alkoxyalkoxy-substituted alkyl groups such as (n) butoxyethoxy)ethyl group, 2-(2(i s o) butoxyethoxy)ethyl group, 2(2-(2-ethylhexyloxy)ethoxy)ethyl group; allyloxyethyl group, 2-phenoxyethyl group, 2
- Substituted alkyl groups such as benzyloxyethyl group; 2-acetyloxyethyl group, 2-propionyloxyethyl group, 2-(n)butyryloxyethyl group, 2-(iso
) Acyloxy-substituted alkyl groups such as butyryloxyethyl group and 2-trifluoroacetyloxyethyl group; methoxycarbonylmethyl group, ethoxycarbonylmethyl group, (n) propoxycarbonylmethyl group, (iso) propoxycarbonylmethyl group, (n) ) butoxycarbonylmethyl group, (iso)butoxycarbonylmethyl group,
2-ethylhexyloxycarbonylmethyl group, benzyloxycarbonylmethyl group, furfuryloxycarbonylmethyl group, tetrahydrofurfuryloxycarbonylmethyl group, 2-methoxycarbonylethyl group, 2-ethoxycarbonylethyl group, 2-(n) Propoxycarbonylethyl group, 2-(iso)propoxycarbonylethyl group, 2-(n)butoxycarbonylethyl group, 2
-(iso)butoxycarbonylethyl group, 2-(2-
Substituted or unsubstituted alkoxycarbonyl-substituted alkyl groups such as ethyl group, 2-benzyloxycarbonylethyl group, 2-furfurylcarbonylethyl group; 2-methoxycarbonyloxyethyl group, 2-ethoxycarbonyloxy Ethyl group, 2
-(n) propoxycarbonyloxyethyl group, 2-(
iso) propoxycarbonyloxyethyl group, 2-(
n) Butoxycarbonyloxyethyl group, 2-(iso
) Butoxycarbonyloxyethyl group, 2- (2-ethylhexyloxycarbonyloxy)ethyl group, 2-
Substituted or unsubstituted alkoxycarbonyloxy-substituted alkyl groups such as benzyloxycarbonyloxyethyl group and 2-furfuryloxycarbonyloxyethyl group;
Examples include heterocyclic-substituted alkyl groups such as furfuryl group and tetrahydrofurfuryl group.

Further, examples of the cycloalkyl group represented by R1 and R2 include a cyclopentyl group and a cyclohexyl group.

Furthermore, the substituted phenyl groups represented by R1 and R2 include those having a 01-C8 linear or branched alkyl group as a substituent, and 01-C4 linear or branched alkoxy groups. Examples include those having a group, those having a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom, and those having a nitro group, a cyano group, and a trifluoromethyl group.

Among the groups represented by R1 and R2, particularly advantageous ones include a hydrogen atom, a linear or branched alkyl group of 01 to C8, an alkoxyalkyl group of 03 to C8, a benzyl group, a 2 -phenylethyl group, allyl group, etc.

Examples of the lower alkyl group and lower alkoxy group represented by X and Y include 01 to C4 linear or branched alkyl groups and C1 to C4 linear or branched alkoxy groups; The halogen atom represented by and Y includes a fluorine atom, a chlorine atom, and a bromine atom.

More specific examples of the dyes represented by the general formula (1) include those shown in Table (1).

When forming a coloring material layer containing the above-mentioned dye in the thermal transfer sheet of the present invention, the method is not particularly limited, and usually the dye is dissolved or dispersed in the form of fine particles in a medium together with a binder. An ink is prepared, and the ink is applied onto a base film and dried to form a coloring material layer on the base film.

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 a binder with a softening point and/or heat distortion temperature of 100°C or higher is used. is preferred.

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 other organic materials. Examples include resins soluble in solvents or water.

These resins may be selected as appropriate depending on the solvent 4 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 40% by weight, preferably 5 to 30% by weight based on the total weight of the ink composition.

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-mentioned components, the above ink also contains organic and inorganic non-sublimable fine particles, dispersants, antistatic agents, antiblocking agents, antifoaming agents, antioxidants, clay conditioners, A mold release agent 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 flexible resin, it is possible to use a thermal head with improved running properties6.

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, Maki Shoten 19)
``Coating method'' published in 1979).

On the other hand, an ink composition for a thermal transfer sheet, which is another object of the present invention, contains a styryl dye represented by the general formula (I), a resin as a binder, and an organic solvent and/or water. It is something that

The details of the styryl dye are as described above.

Further, the binder is specifically selected from among the above-mentioned water-soluble or organic solvent-soluble resins, depending on the solvent.

Among the aforementioned resins, those with a heat distortion temperature and/or softening point of 10
Particularly preferred is one having a temperature of 0°C or higher. 7 As the organic solvent, the above-mentioned solvents are used. In addition, additives such as the above-mentioned non-sublimable fine particles, dispersants, antistatic agents, antiblocking agents, antifoaming agents, antioxidants, viscosity modifiers, and mold release agents may also be used.

Furthermore, in the ink composition of the present invention, the general formula (1
) The amount of the pigment used is 1 to 30% by weight, preferably 3 to 20% by weight, based on the total weight of the ink.

The method for preparing the ink composition of the present invention is to place a mixed solution consisting of a pigment, a solvent, and a resin in a suitable container equipped with a stirrer, heat it as necessary, or add additives, etc., to prepare the pigment. The pigment can be adjusted by dissolving it in a solvent, or by using a paint conditioner, ball mill, sand grind mill, etc., to uniformly disperse the pigment in the solvent by adding additives as necessary.

(Actions and effects of the invention) The general formula (I) used in the heat-sensitive transfer sheet of the invention
The styryl dye shown in has a clear yellow color, so it is suitable for obtaining full color records with good color reproducibility by combining with appropriate cyan and magenta colors, and it is also suitable for obtaining full color records with good color reproducibility. Because it is easily thermally diffused and has a large molecular extinction coefficient, it is possible to obtain high-speed recording with high color density without placing a large burden on the thermal head. Furthermore, 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, particularly in terms of light resistance. In addition, since the pigment has good solubility in organic solvents and dispersibility in water, it is easy to prepare a highly concentrated ink in which the pigment is uniformly dissolved or dispersed. It is possible to obtain a heat-sensitive transfer sheet coated uniformly and with high concentration. Therefore, by using these heat-sensitive transfer sheets, recording with good uniformity and color density can be obtained.

Furthermore, 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 coated on a current-carrying film that generates heat when energized, and used as a current-carrying thermal transfer sheet.

(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) Ink type CF13 for 8 Polysulfone resin 1 10 g Total 115 g 0 for 10 minutes to prepare ink.

b) Preparation of transfer sheet The above ink was applied to a polyethylene terephthalate film (6 μm
A transfer sheet was obtained by coating the film on a layer (with a thickness of 1 μm) and drying it. The heat-resistant lubricity treatment of the polyethylene terephthalate film was performed by adding 8 parts by weight of a polycarbonate resin having a repeating structural unit represented by the following formula to the polyethylene terephthalate film and 1 part by weight of a phosphate ester surfactant (trade name: NIBLYSURF A-208B: This was carried out by applying a solution consisting of 91 parts by weight of toluene (product of Daiichi Kogyo Seiyaku Co., Ltd.) and drying (dry film thickness: 0.5 μm).

1 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 were coated on synthetic paper (product name: Yupo FPG150, manufactured by Oji Yuka Co., Ltd.) using a wire bar, dried to form a film with a thickness of 5 μm, and then heated in an oven at 100°C. An image receptor was prepared by heat treatment for 30 minutes.

d) Transfer recording The ink-applied surface of the above transfer sheet was overlapped with the recording medium and recorded under the following conditions using a head, and a clear yellow color was obtained as shown in Table (2).
It was possible to obtain a record of uniform color density as shown in the figure.

Recording conditions Main scanning and sub-scanning density: 28 dots)/mm Recording
Electric crab 0: 25W/Dot head heating time: 1
0 m5ec The color density was measured using Densitometer 2 Model TR-927 manufactured by Macbeth Company, USA.

A light fastness 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), and the degree of discoloration after 40 hours of irradiation was determined as shown in Table 2. ) is shown as ΔE1 value.

Furthermore, the transfer sheet and the recorded matter were stable against heat and moisture, and had excellent storage stability in the dark.

The dye used in this example was synthesized by reacting 3-methoxy-4-formyl-N,N-di(iso)butylaniline and malononitrile in ethanol, and had a maximum absorption wavelength in acetone. were as shown in Table (2). The melting point was 113-114°C.

Examples 2 to 10 Preparation of ink and transfer sheet in the same manner as in Example 1 using the pigments shown in Table (2) below among the pigments shown in Table (1) above in place of the pigments used in Example 1. As a result of the preparation and transfer recording, it was possible to obtain clear yellow records with the color densities shown in Table (2), and the light resistance was also good as shown in Table (2).

Comparative Examples 1 to 3 The following known dyes were used in place of the dyes used in Example 1, and ink preparation, transfer sheet production, transfer recording, and light fastness tests were carried out in the same manner as in Example 1. The results shown in (2) were obtained.

Pigments used in comparative examples Comparative example 1 H3 (Unexamined Japanese Patent Publication No. 59-78895 Dye described in Example 1) Comparative example 2 H3 (Unexamined Japanese Patent Publication No. 60-28451 Dye described in Example 1) 4 Comparative example 3 CI! .

(Dye described in Example 1 of JP-A No. 60-28453) Example 11 A transfer sheet was prepared in the same manner as in Example 1, using the ink prepared by the following method instead of the ink used in Example 1. As a result of carrying out transfer recording, it was possible to obtain a recorded matter with a clear yellow color and a uniform color density of 2.25.

Furthermore, the results of the light fastness test of the obtained recorded product and the dark storage test of the transfer sheet and the recorded product were both good.

Preparation of ink Same pigment as Example 1 (Table (1), No. 4)
5 gAS resin** 10
g Toluene 90g5 **AS resin, product name: Denka AS-3 (Denki Kagaku Kogyo ■ product) (Picat softening point (JISK-6870) 10
5°C) 6 Table (2)

Claims (2)

[Claims] (1) A binder and the following general formula (I) on the base film
▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R^1 and R^2 are hydrogen atoms, substituted or unsubstituted alkyl groups, cycloalkyl groups, allyl groups, or substituted or unsubstituted phenyl groups. and X and Y represent a hydrogen atom, a halogen atom, a lower alkyl group, or a lower alkoxy group, and at least one of X and Y represents a lower alkoxy group). A heat-sensitive transfer sheet comprising: (2) An ink composition for a thermal transfer sheet containing a styryl dye represented by the general formula (I) according to claim (1), a resin as a binder, and an organic solvent and/or water.