JPH03234589A - Thermosensitive transfer sheet and ink composition therefor - Google Patents

Abstract

PURPOSE:To improve light stability by providing a colorant layer containing a binder and a specific tricyanovinyl dye on a base film. CONSTITUTION:A colorant layer containing a binder and a tricyanovinyl dye represented by formula I (wherein R<1> and R<2> are a hydrogen atom, a substituted or non-substituted alkyl group, a cycloalkyl group, an aryl group or a substituted or non-substituted phenyl group and X and Y are a hydrogen atom, a lower alkyl group or a lower alkoxy group and either one of X and Y is the lower alkoxy group and the other one of them is the other group) is provided to a base film. For example, the tricyanovinyl dye represented by the formula I can be obtained by reacting tetracyanoethylene with a compound represented by formula II in an org. solvent. By this method, light stability is improved.

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.

■ Large molecular extinction coefficient.

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

■ Easy to synthesize.

■ Excellent ink suitability.

■ No safety and health problems.

No dye has been found to date that satisfies all of the above conditions, and magenta dyes in particular have various drawbacks and have not yet been found to be satisfactory.

As a magenta dye, it has been reported in Japanese Patent Application Laid-Open No. 60-31563 that a tricyanovinyl dye having the same basic skeleton as the dye used in the present invention is excellent as a dye for recording.
JP-A-59-78896, JP-A-63-203393
It is indicated in the number etc.

However, the dyes shown there still did not have sufficient performance, especially in terms of photostability.

Therefore, the inventor conducted a more detailed study on tricyanovinyl dyes and found that by creating a specific structure as shown in general formula (1), the photostability was improved and other performances were also improved. The present invention was achieved by discovering a tricyanovinyl dye that exhibits good performance.

(Problem H 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 magenta dye that satisfies all of the above conditions.

(Means for Solving the Problems) The present invention provides a thermal transfer sheet characterized by having a binder and a coloring material layer containing a dye having the following general formula (1), and a heat-sensitive transfer sheet represented by the general formula (1). The gist of the invention is an ink composition for thermal transfer sheets containing a tricyanovinyl dye, a resin as a binder, and an organic solvent and/or water.

The present invention will be explained in detail below.

The tricyanovinyl dye represented by the general formula CI) used in the present invention can be produced according to a conventionally known method. represents a hydrogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an allyl group, or a substituted or unsubstituted phenyl group, and X and Y represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group, provided that X and One of Y represents a lower alkoxy group and the other represents another group (wherein R', R'', X and Y have the same meanings as in the above general formula (1)) It can be obtained by reacting the compound represented by the following formula in an organic solvent.

To specifically explain the dye represented by the general formula (I) used in the present invention, in the formula, the unsubstituted alkyl group represented by R' and Rt is a ct-cs linear or Examples of 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-hydroxypropyl group; - Carboxy-substituted alkyl groups such as carboxyethyl 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-trifluoroethyl group; benzyl group, p-chlorobenzyl group, 2-phenylethyl group, etc. Phenyl-substituted alkyl group which may be substituted; 2-methoxyethyl group, 2-ethoxyethyl group, 2(n) propoxyethyl group, 2-(iso)propoxyethyl! , 2-(n)
butoxyethyl group, 2(iso)butoxyethyl group, 2
-(2-ethylhexyloxy)ethyl group, 3-methoxypropyl group, 4-methoxybutyl group, alkoxy-substituted alkyl group such as 2-methoxypropyl group; 2-(2-methoxyethoxy)ethyl group, 2-(2 -ethoxyethoxy)ethyl group, 2-(2-(n)propoxyethoxy)ethyl group, 2-(2-(iso)propoxyethoxy)ethyl group, 2-(2-(n)butoxyethoxy)ethyl group, 2 - Alkoxyalkoxy-substituted alkyl groups such as (2-(iso)butoxyethoxy)ethyl group, 2-(2-(2-ethylhexyloxy)ethoxy)ethyl group; allyloxyethyl group, 2-phenoxyethyl group, 2- Substituted alkyl group such as benzyloxyethyl group; 2
-acetyloxyethyl group, 2-propionyloxyethyl group, 2-(n)butyryloxyethyl group, 2-(i
so) 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, tetrahydrofurfuryloxycarbonyl Methyl group, 2-methoxycarbonylethyl group, 2
-ethoxycarbonylethyl group, 2-(It) propoxycarbonylethyl group, 2 (iso) propoxycarbonylethyl group, 2-(n) butoxycarbonylethyl group, 2 (iso) butoxycarbonylethyl group, 2- (2-ethyl Substituted or unsubstituted alkoxycarbonyl-substituted alkyl groups such as hexyloxycarbonyl)ethyl group, 2-benzyloxycarbonylethyl group, 2-furfurylcarbonylethyl group; 2-methoxycarbonyloxyethyl group, 2-ethoxycarbonyloxyethyl group group, 2-(n) propoxycarbonyloxyethyl group, 2-(iso)propoxycarbonyloxyethyl group, 2-(n)butoxycarbonyloxyethyl group, 2(iso)butoxycarbonyloxyethyl group, 2-(2- Substituted or unsubstituted alkoxycarbonyloxy-substituted alkyl groups such as ethylhexyloxycarbonyloxy)ethyl group, 2-benzyloxycarbonyloxyethyl group, 2-furfuryloxycarbonyloxyethyl group; furfuryl group, tetrahydrofurfuryl group, etc. Examples include heterocyclic-substituted alkyl groups.

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

Furthermore, the substituted phenyl group represented by R1 and Rt includes those having a 01 to C8 linear or branched alkyl group as a substituent, and 01 to 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 Rt, particularly advantageous ones include a hydrogen atom, a 01-C8 linear or branched alkyl group, an 03-C8 alkoxyalkyl group,
Examples include benzyl group, 2-phenylethyl group, and allyl group.

Examples of the lower alkyl group and lower alkoxy group represented by X and Y include C1 to C4 linear or branched alkyl groups and C1 to C4 linear or branched alkoxy groups.

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

When forming a coloring material layer containing the above-mentioned dye in the heat-sensitive transfer sheet of the present invention, the method is not particularly limited, and the dye is usually dissolved or dispersed in fine particles in a medium together with an adhesive. 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 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 other organic materials. Examples include resins soluble in solvents or water.

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 to be 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 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. Just apply it so that it covers the steel area (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 tricyanovinyl dye represented by the general formula (I), a resin as a binder, and an organic solvent and/or water. It contains.

The details of the tricyanovinyl 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. As the organic solvent, the above-mentioned solvents are used. In addition, in addition to the above-mentioned non-sublimable fine particles, dispersants, antistatic agents, antiblocking agents,
Additives such as 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 (I
) 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.

In order to prepare the ink composition of the present invention, a mixed solution consisting of a pigment, a solvent, and a resin is placed in a suitable container equipped with a stirrer, heated as necessary, or additives are added, and the pigment is added. 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
Since the tricyanovinyl dye shown in has a clear magenta color, it is suitable for obtaining full color records with good color reproducibility by combining with appropriate cyan and yellow colors. 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. or,
Since the pigment has good solubility in organic solvents and dispersibility in water, it is easy to prepare a highly concentrated ink that is uniformly dissolved or dispersed, and by using such ink, the pigment can be uniformly dissolved or dispersed. A heat-sensitive transfer sheet coated with high concentration can be obtained. Therefore, by using these heat-sensitive transfer sheets, uniformity and color can be improved.
'lli If good records 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.

Further, 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 preparation
Total: 15 g *Product name: Newdel P~1700 (Nissan Chemical Industry ■ product) Heat distortion temperature (ASTMD-648): 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 The above ink was applied to a polyethylene terephthalate film (6 μm
A transfer sheet was obtained by coating the film on the film (thickness) and drying it to a dry film thickness of 1 μl+). In addition, 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 shown by the following formula to the polyethylene terephthalate film and 1 part by weight of a phosphate ester surfactant (trade name: NIBLYSURF A-2088: 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 size: 0.5 μl lI).

C) Preparation of image receptor Saturated polyester resin (product name: TP-220, Nippon Gosei Co., Ltd. product) 10 parts, amino-modified silicone (product name: KF393, Shin-Etsu Chemical Co., Ltd. product) 0.5 parts, methyl ethyl ketone 15 parts , apply a liquid consisting of 15 parts of xylene to synthetic paper (product name: Yubo FPG150, manufactured by Oji Yuka Co., Ltd.) using a wire bar, and dry it to form a dry film.Summary 5
μIm) and further heat-treated at 100° C. for 30 minutes in an oven to produce an image receptor.

d) Transfer recording The ink-applied side of the above transfer sheet was placed on the recording medium and recorded using a thermal head under the following conditions.
) It was possible to obtain a record of uniform color density as shown in ().

Recording conditions Main scanning and sub-scanning density: 8 dots/Tsuru Record Electric Crab 0.25W/dot Head heating time: 1
The 0o+sec color density was measured using a densitometer model TR-927 manufactured by Macbeth, USA.

A light resistance test of the obtained records was carried out using a carbon arc fade meter (manufactured by Suga Test Instruments Co., Ltd.) (black panel temperature 63±2°C). ) is shown as a ΔE* value. In addition, the transfer sheet and recorded matter are stable against heat and moisture.
It had excellent storage stability in the dark.

The dye used in this example was 3-methoxy-N.

It was synthesized by reacting N-di(iso)butylaniline and tetracyanoethylene in N,N-dimethylformamide, and the maximum absorption wavelength in acetone is as shown in Table (2). Melting point is 116-11
The temperature was 7°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 fabrication and transfer recording, it was possible to obtain clear magenta recordings 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 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.

Dye used in comparative example Comparative example 1°N (dye described in Example 1 of JP-A-59-78896) Comparative example 2°N (dye described in Example 1 of JP-A-60-31563) Comparative example 3°N (dye described in Reference Example 1 of JP-A-63-203393)
Example 11 A transfer sheet was prepared and transfer recording was performed in the same manner as in Example 1, using an ink prepared by the following method instead of the ink used in Example 1. As a result, a bright magenta color of 2.15 It was possible to obtain a record of uniform color density. Further, the results of the light fastness test of the obtained recording and the dark storage stability test of the transfer sheet and the recording were both good.

Ink Preparation 5 g of the same pigment as in Example 1 (Table 1 above)
) Positive 4) As resin 1 10g toluene
90g cyclohexanone
10g total 1
15g** AS resin, product name: Denka AS-S (Denka Kagaku Kogyo product) (Pikaft softening point (JISK-68
70) 105℃) Table (2) 1) Measured values in acetone

Claims (2)

[Claims] (1) A binder and the following general formula (I
) ▲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. represents a group, and X and Y represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group, provided that either X or Y represents a lower alkoxy group, and the remaining one represents another group) A heat-sensitive transfer sheet characterized by having a coloring material layer containing a tricyanovinyl dye. (2) An ink composition for a thermal transfer sheet containing a tricyanovinyl dye represented by the general formula (I) according to claim (1), a resin as a binder, and an organic solvent and/or water. thing.