JPH0381195A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To form a color image excellent in image stability such as fixing properties, light fastness or the like by providing a heat-diffusible dye-containing layer and a heat-meltable layer containing a heat-meltable compound and a specific compound on a support. CONSTITUTION:At least a heat-diffusible dye-containing layer containing a dye having heat-diffusibility and capable of forming a complex along with a metal ion and at least a heat-meltable layer containing a heat-meltable compound and a compound represented by formula I(I) are formed on a support. In the formula (I), M is a metal, X1, X2 and X3 are respectively a ligand compound bondable to a metal ion represented by M through a coordinate bond and may be mutually same or different, R1, R2, R3 and R4 may be mutually same or different and are an alkyl group, an aryl group, a cyano group or a heterocyclic residue, l is 1, a or 3, m is 0, 1 or 2, n is 0 or 1 and p is 1 or 2.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-sensitive transfer material, and more specifically, the present invention relates to a heat-sensitive transfer material that is stable against heat, light, etc., has excellent fixing properties, has multiple gradations, and has high sharpness. The present invention relates to a heat-sensitive transfer material capable of recording an image on plain paper or the like through a heat-sensitive transfer process.

[Background of the invention]

Thermal transfer materials are currently used in a variety of fields. For example, it is used as a transfer material for copying.

That is, for example, as a method for obtaining color hard copies, color recording technologies such as inkjet, electrophotography, and thermal transfer are being considered, but among these, thermal transfer methods are easy to operate and maintain, are compact, and have a compact size. It is advantageous because it has excellent features such as low cost and low running cost.

Thermal transfer methods include (1) a method in which a transfer sheet having a meltable ink layer on a support is heated by a thermal head, and the ink is melted and transferred onto the transfer sheet; A thermal diffusion transfer method (so-called sublimation transfer method) in which a transfer sheet having a layer containing a pigment (so-called sublimation pigment) is heated by a thermal head to transfer the heat-diffusible pigment.
However, the thermal diffusion transfer method (■) is better because it can control the gradation of the image by changing the amount of dye transferred by changing the thermal energy of the thermal head.
This is advantageous for full color recording.

However, with the thermal diffusion transfer method, the dye in the resulting image is retransferred to other media or diffused during storage, resulting in a decrease in image density and deterioration of image sharpness over time. This tendency was particularly noticeable when a transferred image was formed on plain paper.

In order to improve this problem, Japanese Patent Application Laid-Open No. 59-109394
The issue discloses a heat-sensitive transfer recording material in which a layer containing a sublimable dye and a heat-melting layer containing a heat-melting compound and a compound that reacts with the dye to suppress sublimation are provided on a support. There is. If this material is used, the sublimable dye that diffuses and transfers in response to thermal energy reacts with the sublimation suppressing compound contained in the heat-melting compound that transfers when heated above a certain level of thermal energy, resulting in image reception. An image is formed on the paper using dyes with low thermal diffusivity.

Chelateable dyes are known as dyes used in such systems, and metal ion salts or metal ion complexes that can form complexes with chelate dyes are known as sublimation inhibiting compounds. However, since known salts of metal ions or complexes of metal ions (hereinafter referred to as metal sources) have low solubility in heat-fusible compounds, it is difficult to add them to the heat-fusible layer or at sufficient concentrations. It has disadvantages such as not being able to be added or causing unevenness in images due to precipitation and the like.

In addition, many of the known metal sources are colored themselves, and there is also a problem in that the color purity of the transferred metal source deteriorates, especially in low-density areas. Furthermore, since the reaction between the metal source and the chelatable dye is slow, there is a problem in that some dye remains that cannot be chelated.

[Purpose of the invention]

The present invention has been made to improve the above-mentioned drawbacks of conventional thermal transfer materials.

That is, a first object of the present invention is to provide a heat-sensitive transfer material capable of forming color images with excellent image stability such as fixability and light resistance.

A second object of the present invention is to provide a metal source that can be uniformly added to a heat-fusible layer at a high concentration, thereby providing a heat-sensitive transfer material using the metal source.

A third object of the present invention is to provide a heat-sensitive transfer material using the metal source by providing a metal source that is substantially free of coloring.

A fourth object of the present invention is to provide a heat-sensitive transfer material using a metal mace by providing a metal source that has rapid reactivity with a chelatable dye.

As a result of intensive research, the present inventors have found that a heat-diffusible dye-containing layer containing at least a heat-diffusible dye that is heat-diffusible and capable of forming a complex with a metal ion on a support, and at least a heat-fusible compound and the following. The present inventors have discovered that the above object of the present invention can be achieved by a heat-sensitive transfer material characterized by having a heat-fusible layer containing a compound represented by the general formula (1), and have completed the present invention.

General formula (1) In the formula, M represents a metal ion, X+, Xz, and Xs each represent a coordination compound that can coordinate with the metal ion represented by M, and x, xz, and x are They may be the same or different.

R, R, R, and R4 represent an alkyl group, an aryl group, a cyano group, or a heterocyclic residue, which may be different or the same, l represents 1.2 or 3, m
represents 0.1 or 2, n represents 0 or 1, and p represents 1 or 2.

The present invention will be explained in more detail below.

The dye of the present invention that is thermally diffusible and capable of forming a complex with a metal ion (hereinafter referred to as "the chelatable dye of the present invention")
I will explain about it.

The "thermal diffusible dye" of the present invention is what is called a "sublimable dye" in three industrial fields, and these sublimable dyes, that is, heat diffusible dyes, have the ability to sublimate chemically. This includes not only those that transfer in a gaseous state by heating or vaporizing the melt diameter, but also those that diffuse and transfer a binder or the like using heat.

The chelatable dye of the present invention may generally have two or more chelatable ligands in a state capable of forming a complex, but preferably has three or more ligands. As the ligand, a chromophore atom and an auxochrome atom are usually used, but in addition to the chromophore and auxochrome atom, the ligand may have a chelatable group.

Preferred examples of the chelatable dye of the present invention include compounds represented by the following general formula (2) or (3).

General formula (2) In the formula, XI is an atomic group (having a substituent on the ring) necessary to form an aromatic carbocycle or a heterocycle in which at least one ring is composed of 5 to 7 atoms. ), and at least one adjacent carbon atom bonded to the azo group is a nitrogen atom, or a carbon atom substituted with a nitrogen atom, an oxygen atom, or a sulfur atom.

X! represents an atomic group (which may have a substituent on the ring) necessary to complete an aromatic carbocycle or heterocycle in which at least one ring is composed of 5 to 7 atoms, and Y
represents a chelating group (eg, hydroxyl group, amino group, alkylamino group, dialkylamino group, acylamino group, carbamoyl group, sulfamoyl group, aldehyde group, thiol group, alkoxy group, thioalkoxy group, etc.).

General formula (3) In the formula, XI has the same meaning as defined in General formula (2), Zl represents an electron-withdrawing group (e.g. carbamoyl group, cyano group), and Z2 represents an alkyl group or an aryl group. .

Preferred specific examples of the chelatable dye of the present invention are shown below. However, it goes without saying that the invention is not limited to the following examples.

These compounds are disclosed in JP-A-53-35533 and JP-A-59.
It can be synthesized by referring to the method described in, for example, No.-48765.

The thermodiffusible dye-containing layer of the present invention typically has a binder to retain the chelatable dye of the present invention. As a binder, cellulose-based, polyacrylic acid-based,
Water-soluble polymers such as polyvinyl alcohol and polyvinylpyrrolidone, acrylic resin, methacrylic resin, polystyrene, polyvinyl acecool, polyolefin,
There are polymers that are soluble in organic solvents, such as polycarbonate, polysulfone, polyethersulfone, and ethylcellulose. In the case of a polymer soluble in an organic solvent, it may be used not only by being dissolved in the organic solvent, but also in the form of a latex dispersion.

The amount of binder used is 0.1 per bottle of support.
g to 50 g is preferred.

Next, the heat-fusible layer will be explained.

The metal source represented by the general formula (1) contained in the heat-fusible layer will be explained.

M represents a metal ion, preferably a transition metal ion, more preferably a divalent transition metal ion, and specifically preferable examples include w4 (■), nickel (■), zinc (■). , platinum (If), palladium (II
) and divalent ions such as cobalt (I[) ions.

Xt, Xz, and Xx each represent a coordination compound (which may be the same or different from each other) that can coordinate with a metal ion to form a complex. For example, those selected from the coordination compounds described in Chelate Kagaku (5) (Nankodo) can be used.

E represents 1, 2 or 3, m represents 1, 2 or 0, and n represents 1 or O, which means that the complex represented by general formula (1) is tetradentate or hexadentate. Depending on the coordination and/or
Or it is determined by the number of ligands of Xt, Xz, and Xs. p represents 1 or 2, preferably 2.

When p is 2, the coordination groups of the coordination compounds represented by Xt, Xz, and Xs are not anionized.

R+, Rz, Rs, and R4 each represent an alkyl group, an alkyl group, a heterocyclic residue, or a cyano group, and are preferably an alkyl group having 4 to 12 carbon atoms or an alkyl group,
They may also be substituted.

Particularly preferred is a phenyl group or an alkyl-substituted phenyl group.

H+ Here is a concrete example.

However, of course, below The invention is not limited to this example.

(n Ca Hq Y) Specific examples of the ligands represented by B e Xt , Xt , and Xs are shown below.

(1) N.H.

(2) NHzGHz　(NHCHHzCHz)　-Nlh( n=0 or 1 〉 (3) NHz(CHt), N)It ( n=2 or 3 ) (4) CtHsNHCHtCHtNHCzHs (8) CJsNCfhCHJL (12) (1 Below is the general formula (L) Compound represented by (metal sauce) A preferred specific example is shown below.

However, of course However, it is not limited to the following examples.

−1 [Cu(N)ItCHzCHJHt) z] ” [(
C6H5) 4B] z--2 [Ni (NH2CH2CHJ)h) il ” [(
C6H5) 4B] z--3 [GO(NHzCHzCHzN)lz) s] ” [
(C6H5) 4B] t--4 [Zn(NH2CH1CH2NHz) 3] ” [(
Catls) 4B] z--5 [Ni (CJ5NHCH2CHzNHz) 3]”
[(CJs) 4B] z--6 [Ni (CJ5NHCHzCH2NHCtHs) 3
] ” [(C4H6) 4B] z--7 [Ni (NHzCHzCHtNHC)lzcHzN)
It) z] ” [(CaHs) 4B+ !−−9 −10 −11 X−22 [Ni (NHzCHzCHzCHJHz) 3] ”
[(n-CJ,)4B-] t-23 [Ni (CJsNHCllzCHJHz)tl(Nt
hCHzCHzNHz)] ” [(CJs) 4B]
Z--24 -26 -27 The amount of metal source added is 50~
Preferably, it is 200 mol%.

As the heat-melting compound, a compound with a low melting point, i.e. 65-1
Compounds having a melting point of 50"C are preferred, such as waxes such as carnauba wax, ξtu wax and cantellilla wax, higher fatty acids and their esters such as stearic acid and behenic acid, alcohols such as xylitol, acetamide, benzamide, stearic acid. Examples include amides such as ξ-do, ureas such as phenylurea and diethylurea, etc.These heat-melting compounds may themselves act as a binder to form a layer, or may be used with a suitable binder. The binder may be the same as or different from the binder of the heat-diffusible dye-containing layer. Good too.

Further, an intermediate layer may be provided between the heat-diffusible dye-containing layer and the heat-fusible layer, and an overcoat layer may be provided as the uppermost layer.

The support may be anything as long as it has good dimensional stability and can withstand the heat during recording with a thermal head, but thin paper such as condenser paper, glassine paper, polyethylene terephthalate, polyamide, polycarbonate, etc. A heat-resistant plastic film can be preferably used. The thickness of the support is preferably 2 to 30 μm, and the support may have an undercoat layer for the purpose of improving adhesion with the binder and preventing transfer and dyeing of the dye to the support. good.

Further, a slipping layer may be provided on the back surface of the support (the side opposite to the ink layer) for the purpose of preventing the head from adhering to the support.

In addition, it is preferable that the support has sufficient smoothness in order to transfer the dye evenly and with sufficient density. It is 200 sec or more, more preferably 300 sec or more.

The heat-sensitive transfer material of the present invention is preferably produced by coating a heat-diffusible dye-containing layer and a heat-fusible layer on a support in this order. Specifically, a heat-diffusible dye is coated on a support together with a suitable binder and a solvent, or the dye alone is coated together with a solvent to form a heat-diffusible dye-containing layer, and a heat-fusible dye is applied thereon. The heat-fusible layer may be formed by applying the compound, the metal source, the binder, and the solvent, or by applying only the heat-fusible compound and the metal source together with the solvent as needed.

Application methods include hot melt coating,
Alternatively, it can be dissolved in a solvent and applied with a wire bar or the like. Alternatively, it may be printed on the support by a printing method such as a gravure method.

Moreover, the thickness of each layer is preferably 0.1 to 15 μm, more preferably 1 to 8 μm in dry film thickness.

Solvents that can be used during coating include water, alcohols (e.g. ethanol, propatool), cellosolves (e.g. methyl cellosolve), esters (e.g. ethyl acetate), aromatics (e.g. toluene, xylene,
chlorbenzene>, ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, dioxane), chlorinated solvents (e.g. chloroform,
(trichlorethylene), etc.

The thermal transfer material of the present invention has a heat-diffusible dye-containing layer and a heat-fusible layer, and at least two of these layers give yellow, magenta, and cyan images, respectively. It is preferable to have them sequentially so as to contain a dye. Further, if necessary, a layer containing a colorant that provides a black or infrared image may be included.

〔Example〕

Hereinafter, specific examples and comparative examples of the present invention will be described. However, as a matter of course, the present invention is not limited to the examples described below.

Example-1 A mixture having the following composition was treated with a paint conditioner to obtain a uniform yellow dye solution containing a heat-diffusible dye.

Exemplary dye Dye-(1) 2g Polyvinyl butyral resin 3g Methyl ethyl ketone 30I111 Toluene
30 d Add the above dye solution to a thickness of 15
A heat-diffusible dye-containing layer was formed on a support made of a μm polyimide film by coating and drying using a wire bar so that the coating amount after drying was 1.0 g/rrf.

A heat-fusible layer coating solution having the following composition (aqueous dispersion containing the following substances) was applied onto the above layer so that the metal source (X-2) was applied at 0.8 g/nf, and dried. A thermal transfer material-1 was prepared.

Dispersion containing 2g of Permarin PN (Sanyo Kakai) 20d Exemplary Metal Source (X-2)
20 - 2wt% methanol solution of anionic activator 0.6 - In the same manner, thermal transfer materials 2 to 10 were prepared by changing the dye and metal source as shown in Table 1.

The obtained thermal transfer material and white coated paper were superimposed and thermal transfer recording was performed using a thermal head. Table 1 shows the reflection density values of the obtained images.

The recording conditions are as follows.

Line density of main scanning and sub-scanning: 4 dots/1TII11
Recording power: 0.6 w/dot Table 1 Comparative dyes are as follows.

Dye-(A) Dye-(B) H As shown in Table-1, if the thermal transfer material of the present invention is used,
A transferred image with high density, uniformity, and high color purity can be obtained. In addition, thermal transfer material using nickel stearate or copper benzoylacetone as a metal source-1
In Samples No. 1 and 12, unevenness was observed in the transferred image, and a decrease in color purity of the image was observed due to the color of the metal source.

Example 2 (Image storage stability test) A polyvinyl chloride sheet was overlaid and closely adhered to the transferred image obtained in Example 1, and left at a temperature of 50''C for 7 days.

No decrease in density was observed in the images obtained with thermal transfer materials 1 to 7, but in the images obtained with thermal transfer materials 8 to 10, the image density on the receiving paper was significantly increased by retransferring to the dye or polyvinyl chloride. A significant decrease was observed. In addition, blurring was observed in the images obtained with the thermal transfer materials -8 to 10, but not in the images obtained with the thermal transfer materials -1 to 7. That is, images obtained using the heat-sensitive transfer material of the present invention have good fixing properties, and retransfer and deterioration of sharpness due to dye diffusion after image formation are significantly improved.

Next, the image obtained in Example 1 was irradiated with light for 48 hours using a xenon fade meter. In the images obtained with the thermal transfer material according to the present invention, a decrease in image density of only 3 to 8% was observed, but compared to the comparative thermal transfer materials -8 to 10.
In the images obtained, the image density decreased by 30 to 40%. Furthermore, in the case of 11.12, the image density was partially lowered, and the density unevenness was further enlarged. That is, images obtained using the heat-sensitive transfer material of the present invention are also excellent in light resistance.

Example 3 A thermal transfer material 13 having the following composition was prepared on a support made of a polyimide film having a thickness of 15 μm. Note that the following first layer and second layer were coated on the support as an aqueous dispersion coating solution containing a dye solution and a metal source dispersion, respectively, in the same manner as in Example-1.

1st layer (heat-fusible dye-containing N) Exemplary dye D y e -120.4 g/n (polyvinyl butyral 0.6 g/rrr 2nd layer (heat-fusible layer) polyvinyl pyrrolidone 0.5 g/rr? Metal source ( X-26) 0.8g/podiethylurea
Thermal transfer materials -14 to 20 were the same as the thermal transfer material -13 except that the dye, metal source, heat-melting compound, and binder of the second layer were changed as shown in Table-2 in the same way as the thermal transfer material-13. was created.

The resulting heat-sensitive transfer material and the polyvinyl chloride surface of an image-receiving paper prepared by applying polyvinyl chloride (approximately 11.0 g and 10 f) on cast-coated paper were overlapped, and recording was carried out in the same manner as in Example-1. As shown in Table 2, the image densities obtained are as follows: thermal transfer materials of the present invention -13 to 17 provide high density and even images, while comparison samples -18 to 20 provide images with low density. No image was obtained and uneven transfer was observed.

Example 4 A thermal transfer material 21 was obtained in which layers having the same structure as those of the thermal transfer materials 1, 2, and 3 of Example 1 were coated on a polyimide film support having a thickness of 15 μm. This thermal transfer material
21, the layers each consisting of two layers in the thermal transfer materials-1, 2, and 3 of Example-1 were sequentially placed on the same plane on a support.
In other words, two layers of each layer were placed next to each other and were coated and shaped as shown in FIG.

In Figure 1, ■ is a yellow dye-forming part, ■ is a magenta dye-forming part, and ■ is a cyan dye-forming part, 1 is a polyimide film support, 2 is a yellow dye-containing heat-diffusible dye-containing N (the composition is 3 is a magenta dye-containing heat-diffusible dye-containing layer (the composition is the same as the dye-containing layer of thermal transfer material-2 of Example-1), 4 is cyan dye-containing heat-diffusible dye-containing N (composition is the same as the dye-containing layer of thermal transfer material-3 of Example-1)
, 5 is a heat-fusible layer (composition is the heat-sensitive transfer material of Example-1)
(same as the thermofusible layer in No. 1).

On the other hand, a comparative thermal transfer material 22 was prepared in which the thermal fusible layer 5 of FIG. 1 was replaced with the thermal fusible layer of the thermal transfer material 12 of Example 1.

Using thermal transfer materials 21 and 22, full-color transfer images were produced based on the image information. That is, the yellow, magenta, and cyan pigment forming portions r, ff,
A dye image was formed on H, and the dye images formed on r, n, and m were sequentially transferred onto the same image-receiving paper to obtain a full-color image. Note that the image receiving paper used in Example-1 was used.

Further, the density modulation was adjusted by changing the heating time of the thermal head based on the image information.

The image obtained by transferring using the thermal transfer material-21 is
An even, full-color image with good gradation and high maximum density was obtained. Moreover, comparative thermal transfer material-22
The maximum concentration was slightly low, and density unevenness was observed. Further, in the low concentration area, there was noticeable coloring that was presumed to be caused by the metal source.

The image obtained with the thermal transfer material-21 also gave good results in the image preservation test according to Example-2.

That is, according to the present invention, even for full-color image recording,
The effects of the present invention are effectively exhibited.

〔Effect of the invention〕

As described above, the heat-sensitive transfer material of the present invention is capable of forming color images with excellent image stability such as fixing properties and light resistance. We can provide a metal source that can be added uniformly, or that has virtually no coloration, or a metal source that reacts quickly with chelatable dyes, and provides excellent thermal transfer using such metal sources. It also makes it possible to obtain materials.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the layer structure when the present invention is applied to a heat-sensitive transfer material for recording full-color images. ■...Yellow dye-forming part, ■...Magenta dye-forming part, ■...Cyan dye-forming part, ■...Polyimide film support, 2...Yellow dye-containing thermodiffusible dye-containing layer, 3...
- Heat-diffusible dye-containing layer containing magenta dye, 4... Heat-diffusible dye-containing layer containing cyan dye, 5... Heat-fusible layer.

Claims (1)

[Scope of Claims] 1. A heat-diffusible dye-containing layer containing at least a heat-diffusible dye that is heat-diffusible and capable of forming a complex with metal ions on a support, and at least a heat-fusible compound and the following general formula. A heat-sensitive transfer material characterized by having a heat-fusible layer containing a compound represented by (1). General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, M represents a metal ion, X_1, X_2, X_3
each represents a coordination compound capable of forming a coordination bond with the metal ion represented by M, and X_1, X_2, and X_3 may be the same or different from each other. R_1, R_2, R_3 and R_4 represent an alkyl group, an aryl group, a cyano group or a heterocyclic residue, which may be different or the same, l represents 1, 2 or 3, m is 0, n represents 0 or 1; p represents 1 or 2;