JP3050623B2 - Thermal transfer recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording method, and more particularly to a thermal transfer recording method using a thermal transfer recording material capable of forming an image with a metal chelate dye on an image receiving material.

[0002]

2. Description of the Related Art As a method for obtaining a color hard copy, a color recording technique using ink jet, electrophotography, thermal transfer, and the like has been studied.

[0003] Of these, the thermal transfer method has advantages in that it is easy to operate and maintain, that the apparatus can be reduced in size and cost can be reduced, and that the running cost is low.

In this thermal transfer system, a transfer sheet (also referred to as a thermal transfer recording material) having a fusible ink layer on a support is heated by a thermal head to heat the ink to a transfer-receiving sheet (also referred to as an image receiving material). )), And a transfer sheet having an ink layer containing a heat-diffusible dye (sublimable dye) on a support is heated by a heat-sensitive head to apply the heat-diffusible dye to a transfer-receiving sheet. There are two types of thermal diffusion transfer method (sublimation transfer method) for transferring images. In this thermal diffusion transfer method, the amount of dye transferred is changed according to the change in thermal energy of the thermal head. Can be controlled, which is advantageous for full-color recording.

In the thermal transfer recording of the thermal diffusion transfer system, the dye used in the thermal transfer recording material is important, and the conventional one is not good in the stability of the obtained image, that is, the light resistance and the fixing property. There is a disadvantage that.

[0006] In order to improve this point, Japanese Patent Laid-Open No.
No. 8893, No. 59-109394, No. 60-239
No. 8 discloses a thermal transfer recording method in which a chelatable thermodiffusable dye is used to form an image on an image receiving material with the chelated dye.

Although this method is excellent as a method for improving light fastness and fixing property, it has the following problems.

That is, when a dye is thermally transferred to a transfer receiving sheet (image receiving sheet) by heating with a heat-sensitive head or the like and a chelate dye image is formed on the image receiving sheet, a part of the dye does not form a chelate with metal. It may remain as an unchelated dye (a dye that is not chelated).

As described above, when the unchelated dye remains,
Since the absorption characteristics of the chelate dye and the absorption characteristics of the non-chelate dye are different from each other, there arises a problem that the color purity of an image due to the chelate dye deteriorates. Further, the remaining unchelated dye causes another problem such as poor fixing of an image and deterioration of light resistance.

Therefore, it is important to completely chelate the dye transferred to the image receiving sheet.
The known methods described above are not yet sufficient in that regard.

The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a thermal transfer recording method using a thermal transfer recording material using a chelatable dye, whereby substantially all of the dye forming the image quality is chelated, thereby achieving image density, image storability and hue. Another object of the present invention is to provide a thermal transfer recording method capable of forming an improved image.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heat-sensitive layer containing a heat-diffusible dye capable of forming a metal chelate complex by reacting with a polyvalent metal ion compound. The dye-containing layer surface of the thermal transfer recording material on the body is superimposed on the image receiving surface of the image receiving material and heated according to image information, and the dye is transferred to the image receiving material to form an image on the image receiving material. After that, the image receiving material is multivalently charged on a support.
Contains no metal ion compound, and cures when heated or pressurized
Unchelated dyes, metal ion compounds, or their decomposition
A thermal transfer recording method characterized by applying pressure and / or heat while superposing on a heating material capable of receiving an object .

The present invention will be described in more detail.

The thermal transfer recording material used in the present invention comprises:
A support contains a layer containing a heat-diffusible dye capable of forming a metal chelate complex by reacting with a polyvalent metal ion compound (hereinafter referred to as a heat-sensitive layer).

The thermal diffusible dye used in the present invention is not particularly limited as long as it is a dye compound having a group capable of forming a complex with a polyvalent metal ion described later. ) Or (Chemical Formula 2).

[0016]

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However, in the general formula (Chemical formula 1), X ¹ represents an atom necessary for completing an aromatic carbocyclic or heterocyclic ring in which at least one ring is composed of 5 to 7 atoms. At least one of the carbons adjacent to the azo bond, which represents a group, is (a) a carbon atom, (b) a nitrogen atom, an oxygen atom or a sulfur atom, and X ² has at least one ring having 5 to 7 rings. Represents a group of atoms required to complete an aromatic carbocyclic or heterocyclic ring composed of
Represents a chelating group.

[0018]

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In the general formula (Chemical Formula 2), X ¹ has the same meaning as defined in the general formula (Chemical Formula 1), Z ¹ represents an electron-withdrawing group, and Z ² represents an alkyl group or an aryl group. Express.

Specific examples of the heat-diffusing dyes represented by the general formulas (1) and (2) are described in JP-A-59-78893.
Nos., 59-109394, 60-2398, etc.
Typical examples include compounds represented by the following general formulas (Chemical Formulas 3 to 9).

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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These dyes can be produced according to the synthesis method disclosed in the above publication.

The content of the dye in the heat-sensitive layer is preferably 0.05 to 10 g per 1 m ² of the support.

The heat-sensitive layer is prepared by dissolving or dispersing the heat-diffusible dye together with a binder in a solvent or in the form of fine particles to prepare a heat-sensitive layer coating solution, and applying the heat-sensitive layer coating solution on a support. It can be formed by coating and drying.

The application of the coating solution for the heat-sensitive layer can be performed by a usual coating method or a printing method such as a gravure method.

The thickness of the heat-sensitive layer is 0.1 to
A range of 5 μm is preferred.

As the binder, cellulosic,
Water-soluble polymers such as polyacrylic acid type, polyvinyl alcohol type, polyvinyl pyrrolidone type, acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone, polyvinyl butyral, polyvinyl acetal, nitrocellulose, ethyl cellulose and the like can be mentioned. . These binders may be used not only by dissolving one kind or two or more kinds in an organic solvent, but also by dispersing them in latex form.

The amount of the binder used is 1 m
0.05 to 30 g per ² is preferred.

Examples of the solvent for preparing the paint include water, alcohols (eg, ethanol, propanol), cellosolves (eg, ethyl acetate), aromatics (eg, toluene, xylene, chlorobenzene), and ketones (eg, acetone, Methyl ethyl ketone), ethers (eg, tetrahydrofuran, dioxane), chlorinated solvents (eg, chloroform, trichloroethylene) and the like.

The support has good dimensional stability,
Any material that can withstand the heat of the thermal head during recording may be used, but a thin paper such as condenser paper or glassine paper, or a heat-resistant plastic film such as polyethylene terephthalate, polyamide, or polycarbonate is preferably used.

The thickness of the support is preferably 2 to 30 μm,
Further, the support may have an undercoat layer for the purpose of improving the adhesiveness to the binder and preventing transfer and dyeing of the dye to the support.

Further, an anti-sticking layer may be provided on the back surface of the support (the side opposite to the heat-sensitive layer) for the purpose of preventing the head from sticking to the support.

The heat-sensitive transfer recording material has a heat-fusible layer containing one or more heat-fusible compounds as described in JP-A-59-106997 on the heat-sensitive layer. You may.

As the heat-fusible compound, 65 to 13
A colorless or white compound having a melting point of 0 ° C. is preferably used, for example, waxes such as carnauba wax, beeswax, candeli wax, higher fatty acids such as stearic acid and behenic acid, alcohols such as xylitol, acetamide, benzoamide and the like. And ureas such as phenylurea and diethylurea.

Incidentally, these heat-meltable layers may contain a polymer such as polyvinylpyrrolidone, polyvinylbutyral, and saturated polyester in order to enhance the retention of the heat-diffusible dye.

According to the heat-sensitive transfer recording material used in the present invention, it is possible to obtain cyan, magenta, yellow and black dye images each having gradation, but the heat-sensitive transfer recording material is capable of full-color image recording. The thermosensitive layer containing a heat-diffusible cyan dye, the magenta heat-sensitive layer containing a heat-diffusible magenta dye, and the yellow heat-sensitive layer containing a heat-diffusible yellow dye, a total of three layers, It is preferable to repeatedly apply the coating on the top. Further, a heat-sensitive layer containing a black image-forming substance may be added to the above three layers, and a total of four layers may be sequentially and repeatedly applied on the same surface of the support.

Next, the image receiving material will be described. The image receiving material used in the present invention generally has an image receiving layer provided on a support. In some cases, the support itself can be used as the image receiving material.

Examples of the support for the image receiving material include the following (1) to
Those listed in (3) can be used.

(1) Synthetic paper (polyolefin, polystyrene, etc.), (2) high quality paper, art paper, coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper , Synthetic resin paper, paperboard, cellulose fiber paper, (3) polyolefin,
Various plastic films or sheets such as polyvinyl chloride, polyethylene terephthalate, polystyrene, methacrylate, and polycarbonate can be used.

The image receiving layer is formed of one or more polymers such as polyester resin, polyvinyl chloride or a copolymer resin of vinyl chloride and another monomer (for example, vinyl acetate), polyvinyl butyral, polyvinyl pyrrolidone, polycarbonate and the like. Be composed.

The thickness of the image receiving layer is preferably from 2 to 30 μm.

Next, the polyvalent metal ion which forms a chelate complex by reacting with the above dye will be described.

The polyvalent metal ion is generally contained in the image-receiving layer of the image-receiving material. When the heat-meltable layer is laminated on the heat-sensitive layer of the thermal transfer recording material, the polyvalent metal ion is contained in the heat-meltable layer. It may be.

The polyvalent metal ion may be contained in both the image receiving layer and the heat fusible layer. Examples of the polyvalent metal ion include those belonging to groups I to VIII of the periodic table.
And multivalent metals, among which Al, Co, C
r, Cu, Fe, Mg, Mn, Mn, Ni, Sn, Ti
And Zn are preferable, and Ni, Cu, Cr, Co and Zn are particularly preferable.

Examples of such a compound that supplies a polyvalent metal ion (hereinafter sometimes referred to as a metal source) include inorganic or organic salts of a polyvalent metal and a complex of a polyvalent metal. Salts and complexes of are preferred.

Specific examples include Ni ²⁺ , Cu ²⁺ , Cr
Salts of lower fatty acids of ²⁺ , Co ²⁺ and Zn ²⁺ with acetic acid, etc.
Salts of higher fatty acids such as stearic acid, and salts of aromatic carboxylic acids such as benzoic acid and salicylic acid are exemplified.

Further, a complex represented by the following general formula can also be preferably used.

[M (Q ¹ ) ₁ (Q ² ) _m (Q ³ ) _n ] ^{p +} (Z ⁻ ) _{p where} M is a polyvalent metal ion, preferably Ni
²⁺ , Cu ²⁺ , Cr ²⁺ , Co ²⁺ , and Zn ²⁺ .

Q ¹ , Q ² , and Q ³ each represent a coordination compound capable of coordinating with the polyvalent metal ion represented by M, and may be the same or different.

These coordination compounds can be selected, for example, from the coordination compounds described in Chelate Chemistry (5) (Nankodo).

Z represents an organic anion, and specific examples include a tetraphenylboron anion and an alkylbenzenesulfonic acid anion.

L (the lowercase letter of the alphabet) is 1,
M represents 1, 2 or 0;
Represents 1 or 0, which is determined depending on whether the complex represented by the above general formula is tetradentate or hexadentate, or the number of ligands of Q ¹ , Q ² and Q ³ Is determined by

P represents 1 or 2, preferably 2
It is. When p is 2, the coordination groups of the coordination compounds represented by Q ¹ , Q ² and Q ³ are not anionized.

The metal sources described in JP-B-36-11535, JP-A-55-48210 and JP-A-55-129346 can also be used.

The metal source is preferably added to the image receiving layer of the image receiving material. However, even if it is added to another material, for example, a heat fusible layer laminated on the heat sensitive layer of the thermal transfer recording material, Further, it may be added to both the image receiving layer and the heat fusible layer.

The amount of the metal source to be added depends on the amount of the heat-diffusing dye of the heat-sensitive transfer recording material. Preferably, the heat-sensitive transfer recording material used in combination is yellow, magenta or yellow.
It is 0.5 to 5 times the total molar amount per m ^{2 of} cyan.

The step of forming an image using the above-mentioned thermal transfer recording material and the image receiving material will be described with reference to the drawings. In FIG. 1, the above-described metal is contained in the image receiving layer 2 of the image receiving material 3 comprising the support 1 and the image receiving layer 2. When the ions are present, the dye in the heat-sensitive layer 5 of the heat-sensitive transfer recording material 6 composed of the support 4 and the heat-sensitive layer 5 diffuses and transfers to the image receiving material 3 due to, for example, heat from the heat-generating resistor of the heat-sensitive head 7. Then, it reacts with the metal ions in the image receiving layer 2 to form a chelate dye.

In FIG. 2, when the metal ions are present in the heat-meltable layer 9 provided on the surface of the heat-sensitive layer 5, when the metal ions are present, the heat-sensitive layer 9 comprises the support 4, the heat-sensitive layer 5, and the heat-meltable layer 9. The dye in the heat-sensitive layer 5 of the thermal transfer recording material 10 is diffused and transferred to the heat-meltable layer 9 by, for example, heat from the heating resistor of the heat-sensitive head 7, where it reacts with the metal ions to form a chelate dye, Part or all of the heat-meltable layer 9a containing the chelate dye undergoes cohesive failure or interfacial separation, and migrates to the image receiving material 3.

In the above process, heating is performed using a heat-sensitive head during image formation. As a heating method, a method using a laser beam or a conductive material is added to a support of a heat-sensitive transfer recording material. An energization heating method or the like for heating the support itself by energization can also be used.

However, heating with a thermal head is common, and a specific heating method is described in Photo Industry Separate Volume Imaging Part 2 (edited by the Electrographic Society of Japan), pp. 74-79.

In the thermal transfer recording method of the present invention, the image receiving material on which an image has been formed as described above is subsequently superimposed on a support on a heating material containing no polyvalent metal ion compound. In this state, both materials are pressurized and / or heated as a post-treatment.

By performing post-processing in this manner, unchelated dyes, metal ion compounds, or decomposition products thereof can be removed from the image forming surface of the image receiving material. For the pressurization, for example, a pressurization method using a roller is practically preferable. In this case, the pressing force may be 1 g / cm ^{2 to} 30 kg / cm ² , preferably 10 g / cm ^{2 to 1} kg / cm ^2.
Is good. The heating is performed by bringing the image receiving material into contact with a heated block, a heat roller or a heat drum, passing the image receiving material through a high-temperature atmosphere, or applying a high frequency to the image receiving material. be able to. The heating may be performed by a thermal head. The heating temperature is preferably 70 to 200 ° C, more preferably 9 to 200 ° C.
The heating time is 1 second to 2 minutes, more preferably 5 to 30 seconds.

[0069]

Next, the present invention will be described more specifically with reference to examples.

(Examples 1 to 7) -Preparation of Thermal Transfer Recording Material- The following raw materials were mixed to prepare a coating solution for a heat-sensitive layer containing a heat-diffusible dye.

Heat Diffusion Dye (D-1) 10 g [It is represented by the general formula (Formula 3). Nitrocellulose resin 20 g Methyl ethyl ketone 400 ml Next, the above-mentioned coating solution for the heat-sensitive layer was coated on a 4.5 μm-thick polyethylene terephthalate film. Using a wire bar, coating was performed so that the coating amount after drying was 1.0 g / m ² , and further drying was performed to form a heat-sensitive layer, thereby obtaining a heat-sensitive transfer recording material.

On the back surface of the polyethylene terephthalate film, a nitrocellulose layer containing a silicon-modified urethane resin (SP-2105, manufactured by Dainichi Seika) was provided as an anti-sticking layer.

Similarly, instead of the heat-diffusing dye [general formula (Chem. 3)], a heat-diffusing dye [Chemical formula (Chem. 3), (Chem. 4), (Chem. 5), (Chem. 6), (Chem. 6) The following thermal transfer recording materials were produced.

-Preparation of Image Receiving Material- A polyethylene layer on one side of the paper laminated on both sides with a polyethylene layer [containing an appropriate amount of white pigment (titanium dioxide) and a bluing agent. ] And the following metal source (with a coating amount of 5 g / m ² ) and silicone oil. An image receiving material was prepared by coating polyvinyl chloride containing 15 g / m ² (with a coating amount of 10 g / m ² ).

Metal source: Ni ²⁺ (C ₂ H ₅ NHCH
₂ CH ₂ NH ₂ ) ₃ (Ph ₄ B ⁻ ) ₂ where Ph represents a phenyl group.

-Thermal transfer recording method-The thermal transfer recording material and the image receiving material obtained as described above are overlapped so that the thermal layer surface of the thermal transfer recording material and the image receiving surface of the image receiving material face each other, and the thermal head is thermally transferred. Image recording was performed by applying the recording material from the back side. The recording conditions at this time are as follows.

<Recording Conditions> Linear density of main scanning and sub-scanning 8 dots / mm Recording power 0.6 W / dot Heating time of thermal head: 20 mec to 0.2 me
The heating time was adjusted stepwise between steps c and c.

For each of the obtained images, the maximum reflection density (D _max ) was measured in the following manner, and at the same time, the absorption characteristics, light resistance and stin were measured. The results are shown in Table 1.

Maximum reflection density; optical densitometer [Konica Corporation
The measurement was carried out using a PCA-65 model. Absorption characteristics: spectrophotometric [measured using Hitachi U-3410 type] The results of Example 1 and Example 2 are shown in FIGS. 3 and 4, respectively. Light fastness; light fastness by irradiating an image with a xenon Ford meter for 1 week (D ₀ before exposure to light, D after 1 week of light exposure, and D / D ₀ × 100 as residual ratio of image .) Was measured.

Stin: The density of the white background after the sample was stored at 77 ° C. for one week was measured. Next, the image forming surface on the image receiving material is overlapped with another image receiving material not containing a metal source , that is, an image receiving surface of a heating material.
After heating by a heating roller heated to 0 ° C. for 30 seconds, the maximum reflection density (D
_max ) and the absorption properties, lightfastness and stin were measured.

Table 1 shows the results.

[0082]

[Table 1]

As shown in Table 1, according to the thermal transfer recording method of the present invention, the dye is substantially entirely chelated, so that the maximum density and the image storability are improved.

As shown in FIGS. 3 and 4, the thermal transfer recording materials of Examples 1 and 2 showed improvement in hue as shown in FIGS.

The thermal transfer recording materials of the other examples also showed an improvement in hue due to a decrease in secondary absorption and the like.

Example 8 On the same surface of the support used in Example 1, a heat-sensitive layer for forming a yellow dye image (using the general formula (4) as a dye) and a heat-sensitive layer for forming a magenta image ( A heat-sensitive transfer recording material was prepared by sequentially applying a general formula (Formula 3) as a dye and a heat-sensitive layer for forming a cyan image (using General Formula (Formula 6) as a dye). Note that the same binder as in Example 1 was used for the binder of each heat-sensitive layer. The amounts of the pigment and the binder were the same as in Example 1.

Using the obtained thermal transfer recording material, a full-color image was formed by a video printer (VY-100, manufactured by Hitachi, Ltd.).

Further, when the obtained image was subjected to a heat treatment in the same manner as in Example 1, it was possible to obtain a full-color image having improved density, image storability and hue as compared with an image not subjected to the heat treatment. did it.

Similar results were obtained by using a heating head as a heating method for the post-treatment.

(Examples 9 to 15) In Examples 1 to 7, 100 g / cm was used instead of the post-treatment using the heating roller.
^The operation was performed in the same manner as in Examples 1 to 7, except that the pressure was passed through the rollers at a speed of 3 mm / sec while applying the pressure of ² . The results are shown in Table 2.

[0091]

[Table 2]

As can be seen from Table 2, D
It can be seen that _max does not substantially change, and the weather resistance and stain are improved. The same effect as that after the heat treatment was observed for the hue.

[0093]

According to the thermal transfer recording method of the present invention, after an image is formed, an image forming surface of an image receiving material and a heating material not containing a polyvalent metal ion compound are superimposed as a post-process by applying pressure and / or pressure. Or heating, it is possible to remove unchelated dyes, metal ion compounds, or decomposition products thereof from the image forming surface of the image receiving material, thereby obtaining a color image with improved image density, image storability, and hue. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the principle of a thermal transfer recording method.

FIG. 2 is an explanatory diagram showing the principle of a thermal transfer recording method.

FIG. 3 is a graph showing absorption characteristics of images formed by different thermal transfer recording materials.

FIG. 4 is a graph showing absorption characteristics of images formed by different thermal transfer recording materials.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support 2 image-receiving layer 3 image-receiving material 4 support 5 heat-sensitive layer 6 heat-sensitive transfer recording material 7 heat-sensitive head 9 heat-fusible layer 10 heat-sensitive transfer recording material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-70488 (JP, A) JP-A-59-78893 (JP, A) JP-A-60-2398 (JP, A) JP-A-59-788 62187 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A dye-containing layer surface of a thermal transfer recording material having a layer containing a heat-diffusible dye capable of forming a metal chelate complex by reacting with a polyvalent metal ion compound on a support, and an image receiving material. of overlapping the image-receiving surface is heated in accordance with image information, after forming an image by metal chelate complex on the image-receiving material by transferring a dye image-receiving material, the image receiving material,
Do not contain a polyvalent metal ion compound on the support, heating or
At the time of pressurization, unchelated dye, metal ion compound,
Alternatively , a thermal transfer recording method characterized by superimposing and / or heating a heating material capable of receiving a decomposition product thereof .