JPH10329428A - Thermal transfer dye and thermal transfer sheet using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new dye for thermal transfer recording in high density and obtaining a thermal transfer image of performance of satisfactory light resistance. SOLUTION: The thermal transfer dye is represented by a formula, where R<1> denotes alkyl group, R<2> denotes alkyl group which may have substituent, cycloalkyl group which may have substituent or aryl group which may have substituent, and R<3> , R<4> independently denote hydrogen atom, alkyl group which may have substituent, alkoxy group or halogen atom. R<5> , R<6> independently denotes alkyl group which may have substituent, alkenyl group which may have substituent or aryl group which may have subsituent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye for thermal transfer and a thermal transfer sheet having a dye layer containing the dye. The dye of the present invention is not only preferably used as a dye used in a normal thermal transfer system using a combination of a thermal transfer sheet and an image receiving sheet, but also heat-liquefied dye or the dye itself is transferred to an image receiving paper by heat liquefaction. It can also be used for a heat-vaporization transfer method.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic system, an ink jet system,
A color recording technology using a thermal transfer method or the like is being studied. The thermal transfer recording method has many advantages over other methods because the maintenance and operation of the apparatus are easy and the apparatus and consumables are inexpensive.

[0003] The thermal transfer method includes a transfer method in which a transfer sheet having a heat-meltable ink layer formed on a base film is heated by a thermal head to melt the ink and transfer-record the image on an image receiving layer. There is a method in which a thermal transfer sheet having a dye layer containing a heat transferable dye formed on a base film is heated by a thermal head to transfer the dye onto an image receiving sheet. Since the transfer amount of the dye can be controlled by changing the applied energy, gradation recording is facilitated, which is particularly advantageous for high-definition, high-quality full-color recording.

In order to obtain a uniform image by the thermal transfer transfer method, it is necessary that the dye is completely and uniformly dissolved in the dye layer of the thermal transfer sheet to be used. If the solubility of the dye is poor, the dye crystallizes in the dye layer and becomes non-uniform.
When a transfer image is prepared using such a heat-sensitive transfer sheet, transfer of the dye in the crystallized portion to the image receiving layer becomes insufficient, and a uniform image cannot be obtained. In order to solve these problems, methods such as JP-A-60-53564 have been studied. However, transfer sensitivity, solubility in an ink-forming solvent, storage stability of a dye in an ink, and dye on a heat-sensitive transfer sheet are considered. Further improvements are desired in the storage stability of the dye in the layer, the storage stability of the dye in the image receiving layer on the image receiving paper, the light fastness of the image, and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a yellow heat-sensitive transfer dye and a heat-sensitive transfer sheet capable of overcoming the above-mentioned problems and capable of recording at a high density and having excellent heat resistance. Things.

[0006]

The gist of the present invention is a methine thermal transfer dye represented by the following general formula (I) and a thermal transfer sheet having a dye layer containing the dye on a support. . General formula (I)

[0007]

Embedded image

[0008] (wherein, R ¹ represents an alkyl group, R ²
Represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or an aryl group which may have a substituent, and R ³ and R ⁴ are each independently Represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group, and a halogen atom. R ⁵ , R
⁶ independently represent an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group which may have a substituent. )

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The dye for thermal transfer of the present invention has a structure represented by the general formula (I). Formula (I)
In R ¹ , for example, a methyl group, an ethyl group,
n-propyl group, i-propyl group, n-butyl group, t-
Examples thereof include a linear or branched alkyl group having 1 to 8 carbon atoms such as a butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, and a 2-ethylhexyl group.

When R ² represents a substituted or unsubstituted alkyl group, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-butyl
-Pentyl group, neopentyl group, n-hexyl group, 2-
A linear or branched alkyl group having 1 to 8 carbon atoms such as an ethylhexyl group; or a fluorine atom as a substituent;
A phenyl group substituted with a halogen atom such as a p-fluorophenyl group or a p-chlorophenyl group; a p-tolyl group, an o-tolyl group,
a phenyl group substituted by an alkyl group such as m-tolyl group, p-ethylphenyl group, pn-butylphenyl group;
-Methoxyphenyl group, p-ethoxyphenyl group, p-
an alkyl group having a phenyl group substituted with an alkoxy group such as an n-butoxyphenyl group; a p-nitrophenyl group; a p-cyanophenyl group. When R ² represents a cycloalkyl group which may have a substituent, examples thereof include a cyclopentyl group, a cyclohexyl group, and a p-methylcyclohexyl group.

When R ² represents an aryl group which may have a substituent, examples thereof include a phenyl group; a phenyl group substituted with a halogen atom such as a p-fluorophenyl group and a p-chlorophenyl group; Tolyl group, o-tolyl group, m
A phenyl group substituted with an alkyl group such as a tolyl group, a p-ethylphenyl group, a pn-butylphenyl group;
Methoxyphenyl group, p-ethoxyphenyl group, pn
A phenyl group substituted with an alkoxy group such as -butoxyphenyl group; a p-nitrophenyl group; a p-cyanophenyl group.

When R ³ and R ⁴ represent an alkyl group,
Specifically, a methyl group, an ethyl group, an n-propyl group, i
A straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms such as -propyl group, n-butyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, and 2-ethylhexyl group; No. As the substituent of the alkyl group,
Examples thereof include halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom.

When R ³ and R ⁴ represent an alkoxy group,
Specific examples include an alkoxy group having 1 to 8 carbon atoms corresponding to the above alkyl group. When R ³ and R ⁴ represent a halogen atom, examples thereof include a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom. When R ⁵ and R ⁶ represent an alkyl group, specifically, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, a
-Pentyl group, neopentyl group, n-hexyl group, 2-
Examples thereof include a linear or branched alkyl group having 1 to 8 carbon atoms such as an ethylhexyl group, and the substituent thereof is a methanesulfonylamide group or an ethanesulfonylamide group having 1 to 8 carbon atoms, preferably An alkylsulfonylamide group having 1 to 4; a hydroxy group; a methoxy group, an ethoxy group, a butoxy group and the like having 1 to 8 carbon atoms, preferably 1 carbon atom.
To 4 alkoxy groups; a halogen atom such as a fluorine atom and a chlorine atom; an aryl group such as a phenyl group; an aryloxy group such as a phenoxy group; an acyloxy group such as an acetyloxy group, a propionyloxy group and a benzoyloxy group; And an alkoxycarbonyl group having a total of 2 to 8 carbon atoms such as an ethoxycarbonyl group; an aryloxycarbonyl group such as a phenoxycarbonyl group; a cyano group; a tetrahydrofuryl group.

When R ⁵ and R ⁶ represent an aryl group which may have a substituent, specific examples include a phenyl group, a p-tolyl group, a p-fluorophenyl group and a p-ethoxyphenyl group. Examples thereof include an alkyl group having 1 to 4 carbon atoms, an alkoxy group, and a phenyl group which may be substituted with a halogen atom or the like. When R ⁵ and R ⁶ represent an alkenyl group which may have a substituent, specifically, as an allyl group, a 2-butenyl group or a substituent, an alkyl group such as a methyl group or an ethyl group, a fluorine atom, Examples include a halogen atom such as a chlorine atom and a bromine atom, and an allyl group having an aryl group such as a phenyl group.

Among the dyes represented by formula (I), R ¹ is preferably a linear or branched alkyl group having 1 to 6 carbon atoms. R ² is a phenyl group, an optionally substituted alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, a phenyl group, a tolyl group or a halogen atom, a cyano group, a phenyl group substituted with a nitro group or an alkoxy group. There, the R ^3, R ^4, a hydrogen atom, may be substituted with a fluorine atom alkyl group having 1 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, a halogen atom, R ^5, R ⁶ Is an alkoxy group, an acyloxy group, an alkylsulfonamide group, an alkoxycarbonyl group, a phenoxycarbonyl group, a tetrahydrofuryl group, a phenyl group, a cyano group, a halogen atom, and a carbon atom which may be substituted with 1 as a substituent. ~ 4
Is an alkyl group or an allyl group.

More preferably, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, and R ² is a linear or branched alkyl group having 1 to 4 carbon atoms or R ³ and R ⁴ are a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, a chlorine atom or a fluorine atom, and R ⁵ and R ⁶ are chlorine atoms. Examples of the dye include an alkyl group having 1 to 4 carbon atoms which may be substituted with an atom or a cyano group. Although the method for producing the azomethine dye of the present invention is not particularly limited, for example, the following general formula (II)

[0017]

Embedded image

(Wherein R ¹ and R ² have the same meanings as in the above formula (I)) and the following formula (III)

[0019]

Embedded image

(Wherein, R ^{3 to} R ⁶ have the same meanings as in the general formula (I)) by reacting with an aldehyde compound represented by the following formula at a temperature of about 50 to 150 ° C. Can be manufactured. Examples of the solvent used for this reaction include alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol and amyl alcohol, and organic acids such as acetic acid and propionic acid. These solvents are used alone or as a mixture. Specific examples of the dye used in the present invention include, for example, those shown in Table 1 below, but the present invention is not particularly limited thereto.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

[Table 7]

[0028]

[Table 8]

The dye for thermal transfer of the present invention is usually prepared by dissolving or dispersing the dye with a binder resin in a medium or in the form of fine particles to prepare an ink, coating the ink on a support, and drying. To obtain a heat-sensitive transfer sheet having a dye layer (dye-donor layer) formed on a support, which is used for image formation by a heat-sensitive transfer method. In order to form a full-color image by an image forming method using a thermal transfer method, three colorants of yellow, magenta, and cyan are used. The dye of the present invention is a yellow dye and is used in combination with commercially available magenta and cyan. Further, two or more dyes of the present invention or a mixture of the dye of the present invention and a known dye may be used. The three dyes are arranged so as to form independent regions on a sheet-shaped or roll-shaped support. For example, a yellow area, a magenta area, and a cyan area are arranged in a plane sequence.

As the support, thin papers such as condenser paper and glassine paper, and plastic films having good heat resistance such as polyester, polycarbonate, polyamide, polyimide and polyaramid are suitable. Their thickness may be in the range of 3 to 50 μm. Among the above base films, a polyethylene terephthalate film is particularly advantageous in consideration of mechanical strength, solvent resistance, economy, and the like. If the heat resistance of the polyethylene terephthalate film is not sufficient, the runnability of the thermal head is insufficient, so the heat resistance containing a surfactant, a highly active heat-resistant polymer, etc. on the opposite surface of the dye-donating layer By providing a resin layer, the thermal head can be used with improved running properties.

As the binder resin for preparing the above ink, in order to prevent thermal fusion with the receptor layer during thermal transfer recording,
Although those having good heat resistance are used, those having a softening point and / or heat deformation temperature of 10 ° C. or more are particularly preferable. Specifically, cellulose-based, acrylic acid-based, starch-based water-soluble resins, acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, AS resin, polyethersulfone, polyvinyl butyral, polyester, ethyl cellulose, acetyl cellulose, polyamide And an organic solvent such as a urea resin or a resin soluble in water. These resins are preferably used at a ratio of 20 to 500 parts with respect to 100 parts by weight of the dye.

Examples of the medium for preparing the ink include water, alcohols such as methyl alcohol, isopropyl alcohol and isobutyl alcohol, cellosolves such as methyl cellosolve and ethyl cellosolve, aromatic hydrocarbons such as toluene and xylene, and ethyl acetate. , Esters such as butyl acetate, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, methylene chloride, chloroform,
Chlorinated solvents such as trichlorethylene and chlorobenzene,
Ethers such as tetrahydrofuran and dioxane, N,
Organic solvents such as amides such as N-dimethylformamide and N-methylpyrrolidone can be mentioned. These may be used alone or as a mixture. In the above ink,
In addition to the above components, a release agent can be contained in order to improve the releasability between the heat-sensitive transfer sheet and the image receiving sheet. In addition, a method of applying a release agent on the dye layer is also possible, but in order to more effectively achieve the effects of the present invention, such as color transfer characteristics, it is necessary to include a release agent in the ink. Is more preferred.

As the release agent, polyethylene wax,
Any release agent such as a fluorine-based compound and a silicone-based compound can be used, and among them, a silicone-based compound is preferable. Carboxy-modified,
Amino-modified or epoxy-modified silicone oils or resins can be mentioned. For example, Shin-Etsu Chemical Co., Ltd.
X-22-3710, KF-393, KF-105
Etc. are effective.

Phenolic, hydroquinone,
Antioxidants such as hindered amines and ultraviolet absorbers such as benzotriazoles, benzophenones and thiazolidones may be added and used. In addition, a known surfactant for the purpose of improving coating properties, improving releasability, and improving antistatic properties,
Particularly preferably, a fluorine-based surfactant may be added.

The method of applying the ink on the base film can be carried out using a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or the like, and the thickness of the dye donating layer formed by applying and drying the ink. The thickness is preferably in the range of 0.1 to 5 μm. The image receiving sheet used in combination with the thermal transfer sheet of the present invention has a dye receiving layer on a support. The dye receiving layer is obtained by adding a binder resin and a compound capable of receiving a dye to the resin.

Examples of the binder resin used in the receptor layer include the binder resins used in the ink preparation described above. Examples of the substance capable of accepting a dye added to the resin include those described in JP-A-62-174754. And high boiling organic solvents. The thickness of the receiving layer is 0.
It is preferably from 2 to 40 μm, and particularly preferably from 1 to 15 μm.

As the support, synthetic paper (polyolefin, polystyrene, etc.), high quality paper, art paper, coated paper, polyethylene, polypropylene, polyester (polyethylene terephthalate, etc.), polycarbonate, polyamide film, etc. Laminates can be used. In the image receiving sheet, an intermediate layer having the functions of a cushion layer, an adhesive layer, and a dye diffusion preventing layer may be formed between the support and the receiving layer. The intermediate layer uses a water-soluble binder such as gelatin or an organic soluble binder, and may contain fine particles such as silica, clay, calcium carbonate, titanium oxide, and alumina.

Further, a fluorescent whitening agent may be added to the receiving layer in order to impart a function of improving whiteness and the like. Examples of the fluorescent whitening agent include a stilbene type, a coumarin type and a benzoxazolyl type. Further, in order to improve the releasability between the heat-sensitive transfer sheet and the image receiving sheet, it is preferable to include a release agent on the surface of or in the dye-receiving layer of the dye-receiving material.

Further, isocyanates, aldehydes,
A hardening agent such as an epoxy-based, vinylsulfone-based, or N-methylol-based hardener, the above-described antioxidant, an ultraviolet absorber, and a surfactant can also be used. In this case, slipperiness,
For the purpose of improving the releasability and the like and preventing static charge, it is preferable to use a fluorine-containing surfactant added. The heat-sensitive transfer sheet of the present invention is superimposed on the image-receiving sheet, preferably from the back side of the heat-sensitive transfer sheet, by applying heat energy according to the image material by a heating means, thereby transferring the dye of the dye-donating layer to the receiving layer of the image-receiving sheet. The image can be transferred as an image having excellent image stability, sharpness and resolution. Heating means is not only thermal head, but also laser light, infrared light,
A known device such as a hot pen can be used.

Further, the dye for thermal transfer of the present invention can be prepared by a method other than the above-mentioned transfer method using a thermal transfer sheet and an image receiving sheet.
As described in JP-A-5-221155 and JP-A-7-108711, a heat-liquefied dye or a heat-vaporization transfer system in which a dye itself is heat-liquefied and transferred to an image receiving paper can be used. Further, the thermal transfer dye of the present invention,
It is a yellow dye and is particularly useful for mixing with a magenta dye and a cyan dye to produce a black color tone.

[0041]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. The dye No. Is the NO.
Corresponding to

Example 1 NO. Synthesis of dye 1 6.1 g of 1-phenyl-3-methyl-5-pyrazolone,
6.2 g of p-diethylaminobenzaldehyde was added to acetic acid 3
Then, the mixture was heated and reacted at 118 ° C. for 30 minutes. After cooling to 25 ° C., water was added, and the precipitated crystals were filtered to obtain the desired NO. A crude crystal of the dye 1 was obtained. The crude crystals were subjected to column purification on silica gel using chloroform as a flowing solvent to obtain the desired NO. 6.0 g of the dye 1 was obtained. The maximum absorption of this dye was 456 nm (acetone), and the melting point was 108.5 to 109.0 ° C. Similarly, the dyes in Table 1 were synthesized and used in the following examples.

Example 2 a) Preparation of ink NO. 8 g of the dye 1, 10 g of a phenoxy resin (product name: PKHJ, manufactured by UCC), and 90 g of tetrahydrofuran were treated with a paint conditioner for 10 minutes to prepare an ink.

B) Preparation of heat-sensitive transfer sheet The above ink was coated on a 6 μm-thick polyethylene terephthalate film having a heat-resistant lubricated back surface using a wire bar so that the film thickness after drying was 1.0 μm. And
After drying, a thermal transfer sheet was obtained. The heat-resistant lubrication treatment was carried out on a polyethylene terephthalate film using 8 g of a polycarbonate resin and 1 g of a phosphate-based surfactant (trade name:
(Plysurf A-208B: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and a liquid consisting of 91 g of toluene having a film thickness of 0.1 g after drying.
The coating was performed so as to have a thickness of 5 μm and dried.

C) Preparation of Image-Receiving Sheet 10 g of vinyl chloride-vinyl acetate resin (a resin of vinyl chloride, vinyl acetate and vinyl alcohol and having a vinyl alcohol content of 5% by weight) and a silicone resin (product name: L-700)
2. Nippon Unicar Co., Ltd.) 0.6 g, toluene 40 m
l, a liquid consisting of 40 ml of methyl ethyl ketone, was applied to a synthetic paper (product name: YUPO FPG150, manufactured by Oji Yuka Co., Ltd.) with a wire bar so that the film thickness after drying was 5 μm, and the oven was heated at 100 ° C. for 30 minutes. The image was heated and dried to form an image receiving sheet.

D) Thermal Transfer The heat-sensitive transfer sheet and the image-receiving sheet obtained as described above are overlapped so that the dye layer and the receptor layer are in contact with each other, and the thermal head output from the support of the thermal transfer sheet is 0.12 W / Heat was applied under the conditions of a dot recording power, a dot density of 12 dots / mm, a pulse width of head heating of 10 msec, and the dye was thermally transferred to the receptor layer. As a result, a uniform yellow transfer image was obtained. The recording density on the receiving layer after thermal transfer was measured using a densitometer TR-
927 (using a yellow SPI filter)
2.7, and high-density transfer recording was possible.

E) Evaluation of light fastness On the yellow transfer image obtained above, the method described in JP-A-61-359 was used.
No. 94 of the second embodiment. A cyan dye having the following structure described in 2-1 is used,

[0048]

Embedded image

Using a thermal transfer sheet obtained in the same manner as in the above-mentioned yellow dye, thermal transfer was performed repeatedly to obtain a green transfer image. The effect of the yellow dye on the light fastness of the cyan dye at a black panel temperature of 63 ± 2 ° C. was examined using a xenon lamp fade meter (manufactured by Suga Test Instruments Co., Ltd.). Degree of discoloration after irradiation for 80 hours ｛ΔE ^* (L ^* a ^*
b ^* )｝ was 11.7, and the light resistance was good.

Examples 3 to 14 Using the dyes shown in Table 2 under the conditions of Example 2, the same treatment as in Example 2 was carried out, and transfer recording and a light resistance test were carried out. Was. Table 2 shows the results. Comparative Example 1 Example 2 of JP-A-60-53564 shown below.
A thermal transfer sheet was prepared by the method of Example 2 using the dye of 2-2, and evaluated in the same manner as in Example 2. However, the light resistance test result was poor (ΔE ^* = 52.7). This yellow dye deteriorated the light fastness of the cyan dye. The results are shown in Table 2 below.

[0051]

Embedded image

[0052]

[Table 9]

[0053]

When the heat-sensitive transfer material of the present invention is used,
Uniform and high density thermal transfer recording can be performed, and a thermal transfer image having good light fastness can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 11/00 C09D 11/02 11/02 B41M 5/26 101K

Claims (2)

[Claims] 1. A compound represented by the following general formula (I): (In the formula, R ¹ represents an alkyl group, and R ² represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or a group which has a substituent. R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group, or a halogen atom, and R ⁵ and R ⁶ each independently represent a good aryl group. Represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group which may have a substituent.) 2. A thermal transfer sheet having a dye layer on a support, wherein the dye layer contains the dye according to claim 1.