JP2607933B2 - Thermal transfer material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-sensitive transfer material.

(Prior Art) At present, as a technique relating to a color hard copy, a thermal transfer method, an electrophotographic method, an ink jet method and the like are being vigorously studied. The thermal transfer method has many advantages over other methods because the maintenance and operation of the apparatus are easy and the apparatus and consumables are inexpensive.

The thermal transfer method is a method in which a thermal transfer material having a heat-meltable ink layer formed on a base film is heated by a thermal head to melt the ink, and is recorded on a sheet to be transferred.
There is a method in which a heat-sensitive transfer material in which a color material layer containing a sublimable dye is formed on a base film is heated by a thermal head to transfer the dye onto a transfer-receiving sheet. By changing the energy applied to the head, the transfer amount of the dye can be changed, which facilitates gradation recording, which is particularly advantageous for high-quality full-color recording.

However, there are various restrictions on the sublimable dye used in this system, and very few satisfy all the required performances.

The required properties include, for example, having favorable spectral characteristics for color reproduction, being easy to sublimate, being resistant to light and heat, being resistant to various chemicals, being less likely to decrease sharpness, and recreating images. It is difficult to transfer, it is resistant to various chemicals, it is easy to synthesize, it is easy to make a thermal transfer material, and so on. In particular, development of a cyan dye satisfying these has been desired.

(Problems to be Solved by the Invention) Various cyan dyes for thermal transfer have been proposed, and among them, JP-A Nos. 61-268493 and 62-191191,
The indoaniline dyes described in the specification such as JP-A-63-91287 have relatively excellent performance. However, these methods have serious defects such as a sharpness of a transferred image which is apt to be reduced, a retransfer is easily performed, and a heat fastness is low.

(Object of the Invention) An object of the present invention is to provide a heat-sensitive transfer material containing a cyan dye which has overcome the above-mentioned deficiencies.

(Means for Solving the Problems) The above object of the present invention has been achieved by a heat-sensitive transfer material having a colorant layer containing a dye represented by the following general formula (I) on a support.

General formula (I) In the formula, R ₁ represents an aromatic group or an unsaturated heterocyclic group bonded to X at an unsaturated carbon atom, and R ₂ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a halogen atom, an alkoxy group. A group, an acylamino group, or an alkylthio group;
X represents a nitrogen atom or a methine group, EWG ₁ and EWG ₂
Each represents an electron-withdrawing group.

Some of the compounds represented by the general formula (I) are described in
-60423. However, the patent does not describe any heat-sensitive transfer material, and does not suggest its applicability. In the present invention, it has been clarified for the first time that it can be applied to a heat-sensitive transfer material, and it has been found that defects of a cyan dye conventionally used in a heat-sensitive transfer material can be improved.

Hereinafter, the compound represented by formula (I) will be described in detail.

The electron-withdrawing substituent represented by EWG ₁ or EWG ₂ specifically means a substituent (excluding a hydrogen atom) having a Hammett's substituent constant σp value of 0 or more. Representative EWG ₁
And examples of EWG ₂ are alkoxycarbonyl groups,
Examples include an acyl group, a carbamoyl group, an aromatic group, a cyano group, an unsaturated heterocyclic group bonded by a carbon atom, a sulfonyl group, and an aryloxycarbonyl group.

When X represents a methine group, the methine group may be substituted, and examples of the substituent include an alkoxycarbonyl group,
Aromatic, aliphatic or carbamoyl groups are representative examples.

When EWG ₁ , EWG ₂ , R ₂ and X include a partial method of an aliphatic group, the aliphatic group means a saturated or unsaturated, chain or cyclic, straight or cyclic, having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms. Chains or branches,
It is a substituted or unsubstituted aliphatic hydrocarbon group. Representative examples include methyl, ethyl, propyl, isopropyl, (t) -amyl, hexyl.

When EWG ₁ , EWG ₂ , R ₁ , R ₂ and X include a part of an aromatic group, the aromatic group is a C 6-10, preferably substituted or unsubstituted phenyl group.

When EWG ₁ , EWG ₂ , R ₁ , R ₂ , and X include a part of a heterocyclic group, the heterocyclic group has 1 to 10 carbon atoms, preferably 1 to 10 carbon atoms.
The 6 hetero atoms are preferably a 3- to 7-membered substituted or unsubstituted heterocyclic group selected from a nitrogen atom, an oxygen atom or a sulfur atom. Representative examples of heterocyclic groups include 2-pyridyl, 2-furyl, 2-imidazolyl, 4-pyrazolyl, 1,2,4-triazol-3-yl, or tetradylyl.

When the aliphatic hydrocarbon group, aromatic group and heterocyclic group have a substituent, typical substituents include an alkoxy group (for example, methoxy, ethoxy), an alkylthio group (for example, ethylthio, butylthio), a cyano group, A sulfonyl group (eg, methanesulfonyl, phenylsulfonyl), an alkyl group (eg, methyl, ethyl), an aryl group (eg, phenyl), a halogen atom (eg, chromium,
Fluorine), an alkoxycarbonyl group (eg, methoxycarbonyl, butoxycarbonyl), a carbamoyl group (eg, N, N-diethylcarbamoyl), an acylamino group (eg, acetamido, benzamido), an acyl group (eg, acetyl, benzoyl), an amino group (eg, N, N
-Diethylamino, anilino, N- (2-hydroxyethyl) -N-ethylamino), hydroxyl group, nitro group, sulfonamide group (for example, methanesulfonamide,
Benzenesulfonamide), an acyloxy group (eg, benzoyloxy, acetyloxy), or a sulfamoyl group (eg, N, N-diethylsulfamoyl, N-methyl-N-butylsulfamoyl).

Next, a particularly preferred range of the compound represented by formula (I) will be described.

R ₁ is preferably a substituted or unsubstituted phenyl group.

X is preferably a nitrogen atom or an unsubstituted methyl group, and particularly preferably a nitrogen atom.

R ₂ is preferably an aliphatic group, an aromatic group or an alkoxy group, particularly preferably an aliphatic group or an aromatic group.

EWG ₁ and EWG ₂ is preferably a carbamoyl group, an alkoxycarbonyl group, an acyl group or a cyano group.

Next, typical examples of R ₁ , R ₂ , EWG ₁ and EWG ₂ will be described.

R ₁ is a 4- (N, N-dimethylamino) phenyl group, 4- {N- (2-methanesulfonamidoethyl)-
N-ethylamino} -2-methylphenyl group, 4- (N,
N-diethylamino) phenyl group, 4- (N, N-diethylamino) -2-methylphenyl group, 4- {N- (2-hydroxyethyl) -N-ethylamino} phenyl group,
-Hydroxyphenyl group, 4- {N- (2-cyanoethyl) -N-ethylamino} phenyl group, 5-methyl-1,
2,4-triazol-3-yl group, 4-anilino-2-
Methoxyphenyl group, 4- (N, N-diethyl) -2-acetamidophenyl group, 4-methoxyphenyl group, 4-
(N, N-diethyl) -2-propanamidophenyl group,
Examples thereof include a 2-pyridyl group and a 4- {N, N-bis (2-methoxycarbonylethyl) amino} anilino group.

Examples of R ₂ include a phenyl group, a methyl group, a 4-methoxyphenyl group, a 4-bromophenyl group, a 4-methylthiophenyl group, an ethoxy group and a benzamide group.

Examples of EWG ₁ and EWG ₂ include a cyano group, a methoxycarbonyl group, a phenylcarbamoyl group, a 4-nitrophenyl group, a 2,5-dichlorophenylcarbamoyl group, a phenylsulfonyl group, and a benzoyl group.

Hereinafter, specific examples of the dye represented by formula (I) used in the present invention will be shown. However, the present invention is not limited to these.

Some of the compounds of the present invention can be synthesized by the method described in JP-B-62-60423. Most of the others can be synthesized by the synthetic methods described below or by analogous synthetic methods.

(Synthesis Example) 1. Synthesis of Exemplified Compound (6) Exemplified Compound (6) was synthesized by the following route.

(Step 1) Synthesis of Intermediate Compound 3 Dissolve 1.0 g of 2,4-dimethylthiazole 1 in 20 ml of sufficiently dried tetrahydrofuran, keep the reaction temperature at −60 ° C. under a nitrogen stream, and prepare hexane of (n) -butyllithium. 7.1 ml of a solution (1.55M) was added dropwise. After stirring for 30 minutes, phenyl isocyanate dissolved in 10 ml of tetrahydrofuran
2 , 1.3 g was slowly added dropwise so that the reaction temperature did not rise to -50 ° C or higher. After stirring for 30 minutes, raise to room temperature, water about 50
ml and about 50 ml of ethyl acetate, and the mixture was transferred to a separating funnel and extracted. The mixture was washed with a 10% aqueous hydrochloric acid solution and then neutralized by washing with water. The ethyl acetate layer was dried over anhydrous sodium sulfate, ethyl acetate was distilled off under reduced pressure, and the residue was recrystallized by adding 20 ml of ethanol. The crystals were separated by filtration to obtain 1.0 g of an intermediate compound 3 . The ratio was 28.5%. The melting point of 3 was 190 ° C.

(Step 2) Synthesis of Exemplified Compound (6) 430 mg of 3 was dissolved in 20 ml of ethanol and 10 ml of ethyl acetate, and 652 mg of sodium carbonate dissolved in 10 ml of water was added. Further, 644 mg of 4 was added, and 674 mg of ammonium persulfate dissolved in 5 ml of water was added dropwise at room temperature. After stirring for one hour, the precipitated exemplary compound (6) was separated by filtration and washed sufficiently with water. The yield was 250 mg, the yield was 33.7%, and the melting point was 195 ° C to 196 ° C.

2. Synthesis of Exemplified Compound (2) Exemplified Compound (2) was synthesized by the following route.

(Step 1) Synthesis of Intermediate Compound 6 Dissolve 1.0 g of 2,4-dimethylthiazole 1 in 20 ml of sufficiently dried tetrahydrofuran, keep the reaction temperature at −60 ° C. under a nitrogen stream, and prepare hexane of (n) -butyllithium. 6.8 ml of a solution (1.55M) was added dropwise. After stirring for 30 minutes, 1.7 g of 2,5-dichlorophenylisocyanate 5 , dissolved in 10 ml of tetrahydrofuran, was slowly added dropwise so that the reaction temperature did not rise to -50 ° C or higher. After stirring for 30 minutes, the temperature was raised to room temperature, about 50 ml of water and about 50 ml of ethyl acetate were added, and extracted. Further, it was washed with a 10% hydrochloric acid aqueous solution, washed with water and neutralized. The ethyl acetate layer was dried over anhydrous sodium sulfate, ethyl acetate was distilled off under reduced pressure, and the residue was recrystallized by adding 20 ml of ethanol.
The crystals were separated by filtration to obtain 920 mg of intermediate compound 6 . The ratio was 21.3%.

(Step 2) Synthesis of Exemplified Compound (2) 900 mg of 6 was dissolved in 30 ml of ethanol and 10 ml of ethyl acetate, and 1.4 g of sodium carbonate dissolved in 10 ml of water was added. Further, 1.4 g of 7 was added, and 1.4 g of ammonium persulfate dissolved in 5 ml of water was added dropwise at room temperature. After stirring for 1 hour, the desired exemplary compound (2) precipitated was separated by filtration and sufficiently washed with water. The yield was 450 mg and the yield was 40.3%.

The heat-sensitive transfer material of the present invention is characterized mainly by using the specific dye as described above, and as a first embodiment, a heat-sensitive transfer layer containing the dye as described above includes:
In this embodiment, the transfer layer is a heat-sensitive sublimation transfer layer composed of a heat transferable dye and a binder resin. The heat-sensitive transfer material of the present invention in this embodiment is prepared by dissolving or dispersing the dye of the present invention and a binder resin in an appropriate solvent to prepare a coating solution, and applying the coating solution to one surface of a support, For example, it can be obtained by coating and drying at a coating amount of about 0.2 to 5.0 μm, preferably 0.4 to 2.0 μm to form a heat-sensitive transfer layer.

Further, as the binder resin used together with the above dye, any conventionally known binder resin can be used for such a purpose, and usually has high heat resistance, and does not hinder the transfer of the dye when heated. Those are selected, for example, a vinyl resin such as a polyamide resin, a polyester resin, an epoxy resin, a polyurethane resin, a polyacryl resin (for example, polymethyl methacrylate, polyacrylamide), polyvinyl pyrrolidone, etc., and a polychlorinated resin. Vinyl resin (for example, vinyl chloride-vinyl acetate copolymer, etc.), polycarbonate resin,
Polysulfone, polyphenylene oxide, cellulosic resin (for example, methylcellulose, ethylcellulose,
Carboxymethylcellulose, cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate, etc., polyvinyl alcohol-based resins (eg, partially saponified polyvinyl alcohol such as polyvinyl alcohol, polyvinyl butyral, etc.), petroleum-based Resins, rosin derivatives, cumarone-indene resins, terpene resins, novolak phenolic resins, polystyrene resins, polyolefin resins (eg, polyethylene, polypropylene) and the like are used.

Such a binder resin is preferably used, for example, at a ratio of about 80 to 600 parts by weight per 100 parts by weight of the dye.

In the present invention, as the ink solvent for dissolving or dispersing the pigment and the binder resin, conventionally known ink solvents can be used freely. Specifically, water, alcohols such as methanol, ethanol, isopropyl alcohol, and butanol are used. , Isobutanol, etc., ethyl acetate as an ester type, methyl ethyl ketone as a ketone type such as butyl acetate, cyclohexanone, etc., toluene, xylene, chlorobenzene, etc. as an aromatic type, dichloromethane, trichloroethane, chloroform, etc. as a halogen type. N-dimethylformamide, N-methylpyrrolidone, dioxane, tetrahydrofuran and the like, cellosolves such as methyl cellosolve and ethyl cellosolve, and mixtures of the above-mentioned solvents.
These solvents, the dye used to a predetermined concentration or more,
It is important to select and use the binder resin as one that sufficiently dissolves or disperses. For example,
It is preferable to use a solvent in an amount of about 9 to 20 times the total weight of the dye and the binder resin.

The dyes used in the present invention may be used alone or in combination of two or more. The dye used in the present invention may be mixed with a known dye.

The dye used in the present invention may be used in combination with a known anti-fading agent.

The support used in the construction of the heat-sensitive transfer material of the present invention may be any known one having a certain degree of heat resistance and strength, for example, a thickness of about 0.5 to 50 μm, preferably about 3 to 10 μm. Paper, various processed papers, polyester (eg, polyethylene terephthalate); polyamide; polycarbonate; glassine paper; condenser paper; cellulose ester; fluoropolymer; polyether; polyacetal; polyolefin; polyimide, polyphenylene sulfide, polypropylene, polysulfone; Allophan, polyimide and the like can be mentioned. Particularly preferred is a polyester film.

As a method for applying the ink to the base film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or the like can be used.

The heat-sensitive transfer material as described above is sufficiently useful in the present invention as it is, however, an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye-supporting layer, and by providing such a layer, Adhesion between the heat-sensitive transfer material and the recording material at the time of thermal transfer can be prevented, and an even higher temperature image can be formed using a higher thermal transfer temperature.

As this release layer, even if only an anti-adhesive inorganic powder is simply adhered, a considerable effect is exhibited.Moreover, for example, a silicone polymer, an acrylic polymer, a resin having excellent release properties such as a fluorinated polymer, from 0.01 to It can be formed by providing a release layer of 5 μm, preferably 0.05 to 2 μm.

The inorganic powder or the release polymer as described above has a sufficient effect even if it is included in the dye-supporting layer.

Further, a heat-resistant layer may be provided on the surface of the heat-sensitive transfer material of the present invention in order to prevent adverse effects due to heat of the thermal head.

A dye-barrier layer of a hydrophilic polymer may also be used in the dye-donor member between the support and the dye layer, thereby improving dye transfer density.

The heat-sensitive transfer material of the present invention in a preferred embodiment obtained as described above is overlapped with a conventionally known heat-sensitive transfer material, and from any surface, preferably from the surface of the heat-sensitive transfer material,
For example, by heating according to an image signal by a heating means such as a thermal head, the dye in the heat-sensitive transfer layer is easily transferred to the receiving layer of the heat-sensitive transfer material with relatively low energy according to the magnitude of the heating energy, and is excellent. It is possible to form a color image having sharpness and resolution gradation.

According to a preferred embodiment of the present invention, the thermal transfer material has a sheet shape, or a continuous ribbon or roll shape. A layer of the cyan dye of the present invention alone may be provided thereon, or a layer of a known yellow, magenta or, in some cases, a black dye may be provided in a separate portion. In a preferred embodiment, on a support,
Yellow, magenta, cyan (and possibly black)
The color transfer material layers of the respective colors having the respective sublimable dyes, that is, the regions of yellow, magenta, and cyan (and in some cases, black) are sequentially and repeatedly arranged to form a thermal transfer material.

To perform full-color recording using such an infectious transfer material, for example, the cyan color material layer (cyan dye region)
In a state where is pressed against the heat-sensitive transfer material, a heating pattern corresponding to a picture element for one scanning line is generated in each head element of the thermal head by a color signal corresponding to cyan, and a color material layer is formed according to the heating pattern. Is transferred to the receiving layer of the heat-sensitive transfer material while the heat-sensitive transfer material and the heat-sensitive transfer material are moved for each scanning line, and cyan for one screen is transferred. The same transfer process may be repeated for each color of yellow and magenta (black in some cases) on the screen. The apparatus used for this recording is known, and is described, for example, in JP-A-62-1585.

The dye used in the present invention can be used for heat-sensitive transfer materials other than the sublimation transfer system. That is, the second preferred embodiment of the present invention is an embodiment in which the heat-sensitive transfer layer of the heat-sensitive transfer material is a heat-sensitive melt transfer layer comprising the dye and the wax of the present invention. The heat-sensitive transfer material of this embodiment is obtained by preparing a heat-sensitive transfer layer forming ink composed of a wax containing a dye on one surface of the specific support as described above, and forming a heat-sensitive melt transfer layer from the ink. Can be The ink is a wax having an appropriate melting point, such as paraffin wax,
Microcrystalline wax, carnauba wax,
It is formed by mixing and dispersing a pigment with urethane wax or the like as a binder. The ratio of the dye and wax used is such that the dye is about 10 to 65 in the heat-sensitive melt transfer layer to be formed.
%, And the thickness of the layer to be formed is about
The range of 1.5 to 6.0 μm is preferred. Its manufacture and application on a support can be carried out according to known techniques.

When the heat-sensitive transfer material of the present invention in the second preferred embodiment as described above is used in the same manner as in the first embodiment, the heat-sensitive melt transfer layer is transferred to the material to be transferred, giving excellent printing.

(Effect of the Invention) The transfer image obtained by using the cyan dye represented by the general formula (I) of the present invention hardly deteriorates in sharpness over time. Therefore, a clear image can be held for a long period of time. It also has excellent features such that retransfer to other recording paper hardly occurs and thermal stability is high.

〔Example〕

In the following Examples and Comparative Examples, the production of the thermal transfer material and the thermal transfer material, printing using both materials, and the test of the thermal transfer material were performed as follows.

Example 1 (Preparation of thermal transfer material (1)) Thickness 6 μm with corona treatment on one side as a support
Polyethylene terephthalate film (Toray, Remy
On the corona-treated surface of the film
Coating composition (1) for thermal transfer layer
Applying so that the thickness when dried becomes 1μm
Formed, on the back side of the member, polyvinyl butyral (butper
Le 76 Monsanto) (0.45g / m^TwoPoly (stearin) in
Vinyl acid) (0.3g / m^Two) For the slipping layer
Coated from lofuran solvent.

Coating composition for thermal transfer layer (1) Dye (compound-1) 4 g Polyvinyl butyral resin (Denka butyral 5000-A manufactured by Denki Kagaku) 4 g Toluene 40 ml Methyl ethyl ketone 40 ml Polyisocyanate (Takeda Pharmaceutical Takenate D110N) 0.2 ml Dye Was replaced with other materials to prepare thermal transfer materials (2) to (6) and comparative materials (a) and (b) in Table 1.

(Preparation of thermal transfer material) Synthetic paper with a thickness of 150 μm (Yoji
-FPG-150), a coating composition for a receiving layer (1) having the following composition is applied to the surface thereof by wire bar coating so that the thickness when dried becomes 5 μm, and the material to be thermally transferred (1)
Was formed. After drying with a dryer for temporary drying, the temperature is 100 ° C.
For 30 minutes.

Coating composition for receiving layer (1) Polyester resin (Vylon-280 manufactured by Toyobo) 20 g Amino-modified silicone oil (KF-85 manufactured by Shin-Etsu Silicone)
7) 0.5 g methyl ethyl ketone 85 ml toluene 85 ml cyclohexanone 30 ml The heat transfer material and the heat transfer material obtained as described above are overlapped so that the heat transfer layer and the receiving layer are in contact with each other, and from the support side of the heat transfer material. Using thermal head, thermal head output 0.25W / dot, pulse width 0.15
Printing was performed under the conditions of 15 msec and a dot density of 6 dots / mm, and a cyan dye was image-dyed on the receptor layer of the material to be thermally transferred. As a result, a clear image recording material without uneven transfer was obtained. .

The recorded thermal transfer material thus obtained was placed in a 60 ° C. or 80 ° C. incubator for 10 days, and the stability of the color image was examined. The status A reflection density was measured before and after the test, and the image stability during dark heat storage was evaluated based on the ratio. In addition, bleeding of the image due to thermal diffusion of the dye was observed. The results are shown in Table 1.

It is clear that the dye used in the present invention has better image stability than the comparative example.

Example 2 (Preparation of Thermal Transfer Material (5)) Materials having the following composition were sufficiently mixed and dispersed to prepare a coating liquid for a lubricating heat-resistant protective layer.

Composition of coating liquid Methyl methacrylate 10 g n-butyl acrylate 2 g benzoyl peroxide 0.1 g silica 2.5 g toluene 35 g isopropyl alcohol (IPA) 15 g To this coating liquid, add a mixture of toluene and IPAT to a moderate amount.
It was diluted and coated on a 6 μm-thick polyethylene terephthalate film (hereinafter abbreviated as PET) as a substrate with a wire bar, and dried at 100 ° C. for 1 minute to form a lubricating heat-resistant protective layer having a thickness of about 1.5 μm. .

Next, a hot-melt ink having the following composition was applied to the surface opposite to the heat-resistant protective layer.

Composition of hot melt ink Dye (compound-4) 10 g Lanolin fatty acid barium salt 30 g Carnauba wax 20 g Paraffin wax 20 g Dispersant 0.5 g Liquid paraffin 5 g Methyl ethyl ketone 100 ml at 68 ° C
And a mixture of 130 ml of toluene with a ball mill for about 48 hours.

Next, a 20% by weight polyvinyl chloride-vinyl acetate copolymer resin solution (resin
300 g of 10 parts, 20 parts of toluene and 20 parts of methyl ethyl ketone) were added to the above ink dispersion and dispersed by a ball mill for about 1 hour to prepare a coating composition for the thermal transfer composition.

This coating agent was applied to the surface of the polyester film provided with the lubricating heat-resistant layer using a wire bar, and the drying temperature was 10
After drying at 0 ° C. for 1 minute, a hot-melt ink layer having a thickness of about 5 μm was formed.

When transfer was performed in the same manner as in Example 1 using plain paper as the obtained transfer material and the material to be heat-transferred, clear cyan recording could be obtained. Further, when the image stability of this recorded sheet was examined by a method similar to that of Example 1, very good results were obtained.

Claims (1)

(57) [Claims] 1. A heat-sensitive transfer material comprising a support and a coloring material layer containing a dye represented by the following general formula (I). General formula (I) In the formula, R ₁ represents an aromatic group or an unsaturated heterocyclic group bonded to X at an unsaturated carbon atom, and R ₂ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a halogen atom, an alkoxy group. A group, an acylamino group, or an alkylthio group;
X represents a nitrogen atom or a methine group, EWG ₁ and EWG ₂
Each represents an electron-withdrawing group.