JP2002113958A - Thermal transfer recording method and print - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording method affording excellent quality, shelf stability and durability. SOLUTION: An ink layer of an ink sheet having at least one kind of ink layer containing thermally-diffusive dye on a substrate and an image receiving layer of an image receiving sheet having at least one kind of image receiving layer capable of receiving the thermally-diffusive dye on a substrate are laid on each other oppositely, and the thermally-diffusive dye is transferred onto the image receiving layer by heating the sheets in the shape of an image by a thermal head. A protective layer thermally transferable by the thermal head is provided in the area on the image receiving sheet onto which the dye is transferred. In regard to this thermal transfer recording method, the protective layer contains an ultraviolet absorber and a b* value (b2) after the transfer of the protective layer, of the area onto which the dye is not transferred, and the b* value (b1) of this area before the transfer are in the relation of b2-b1<=2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal transfer recording method for recording an image by thermal transfer, and more particularly to a thermal transfer recording method excellent in image quality, image storability and image durability.

[0002]

2. Description of the Related Art Conventionally, as a technique for forming a color or monochrome image, an ink sheet containing a heat-diffusible dye having a property of diffusing and transferring upon heating is opposed to an image receiving layer of an image receiving sheet, and a thermal head or laser is used. A technique is known in which an image is formed by transferring the thermal diffusible dye onto the image receiving layer in an image-like manner by using a heating printing means such as described above. Such a thermal transfer system has a reputation as a method that enables image formation with digital data, does not use a processing solution such as a developing solution, and can form high image quality comparable to silver halide photography.

[0003] However, the resulting images have a disadvantage that they are weaker in storage stability and durability than silver halide photographs. Specifically, 1) fading or bleeding of images due to light, heat, oxygen in the air, moisture, etc. during long-term storage (light resistance, heat resistance) 2) albums, clear files, plastic erasers When the ink is brought into contact with a material having a high dye-dyeing property or a material containing a plasticizer, the dye is reversely transferred to them during long-term storage or the image is blurred (plasticizer resistance). ) If water, juice, alcohol, coffee, etc. is spilled on the image, the dye is also wiped off when wiping it off, causing discoloration (water resistance, solvent resistance). 4) The place touched by a finger is discolored by sebum (sebum resistance). 5) Image can be obtained by rubbing with an eraser (rub resistance) 6) When a commercially available laminate is processed, especially a cold laminate that can be processed at a low temperature, the laminate can be stored for a long period of time. Dye diffuses and image blurs There was a laminate suitability), and the like of the problem. This is because in silver salt photography, the dye used is protected by a high-boiling solvent or an ultraviolet absorber, whereas in thermal transfer, the dye is simply dispersed in a binder, which directly affects external influences. It is thought that it is easy to receive.

As means for improving the above-mentioned disadvantages, there have been proposed some image forming methods using a reactive dye which forms an image by reacting a compound in an ink layer with a compound in an image receiving layer by thermal transfer. I have. Here, when the compound to be contained in the ink layer side is defined as a dye precursor and the compound to be contained in the image receiving layer is defined as a dye fixing body, for example, JP-A-9-327976, U.S. Pat. No. 4,880,76.
No. 9,534,479, etc., thermal transfer using a deprotonated cationic dye as a dye precursor and an organic polymer acid or oligomer acid capable of protonating the cationic dye as a dye fixing body. A method for forming an image by reprotonating a cationic dye by using the method has been proposed. JP-A-5-221151 proposes a method in which a dye having a specific structure having a reactive group is used as a dye precursor and an active hydrogen compound is used as a dye fixing body to react them by thermal transfer to form an image. ing. Further, JP-A-59-78893, JP-A-59-10
No. 9394, No. 60-2398, and the like, a heat-diffusible dye capable of chelation (hereinafter also referred to as a post-chelate dye) as a dye precursor, and a metal ion-containing compound (hereinafter also referred to as a metal source) as a dye fixing body. There is disclosed a method of forming an image by containing a metal chelate by reacting them after thermal transfer (hereinafter sometimes referred to as a post-chelate method).

In particular, an image formed using a post-chelating dye and a metal source is less likely to cause fading and bleeding of the dye even if the image-receiving material on which the image is formed is left under high temperature and high humidity for a long time. Are also superior to conventional thermal diffusion dye images.

[0006] However, the effects on image durability such as plasticizer resistance, rub resistance, solvent resistance, etc., were still insufficient.

In recent years, as means for improving image durability,
On the image forming surface of the image receiving sheet, a protective layer transfer sheet having a heat transferable protective layer is superimposed, and the protective layer is transferred using a heating means such as a thermal head or a heat roller. A method of providing a protective layer has been used. By providing a protective layer on an image, it is possible to improve the physical resistance of the image, such as the rub resistance, water resistance, solvent resistance, and sebum resistance, as described above. Also, in the protective layer,
Absorbs or blocks radiation or substances that have the ability to alter or decompose dyes, such as ultraviolet absorbers or oxidizing effects, to prevent alteration or decomposition of dyes, or to add a chemical to further improve image preservability. The protective layer may be provided with a special function such as preventing the forgery or improving the whiteness of the print by adding a fluorescent whitening agent or the like to the protective layer.

[0008] Further, by simultaneously transferring the protective layer by the heat during the transfer of the protective layer, the dye forming the image is subjected to a recoloring treatment, whereby the image becomes clearer or the dye is transferred to the surface of the image receiving layer. By moving from the inside to the inside, the effect of improving the preservability is expected.

Incidentally, it is preferable that the ultraviolet absorber contained in the protective layer sufficiently cover a wavelength region in which the dye to be used is likely to deteriorate or decompose.
Such UV absorbers often absorb into the visible light range and often have a slightly yellow tint. That is, the protective layer itself is slightly yellowish. For this reason, when the protective layer is transferred to the printing screen, there is a disadvantage that the printing area is colored. In particular, in a region from a highlight to a white background where the transfer amount of the dye is small or not present at all, the color is clearly recognized, thereby deteriorating the image quality. For example, in an image such as a wedding dress having a relatively large number of highlight areas, the highlight portion is undesirably yellowish. For the same reason, in an image in which the size of the protective layer transfer area is smaller than the print size, that is, in an image having a border, since there is a portion from highlight to white background near the border, the difference in the tint from the border portion. However, the image quality is significantly reduced.

When an image is formed by the above-described post-chelation method, light resistance is improved as compared with ordinary dyes.
Even if an ultraviolet absorber is not included, the ultraviolet absorber has a sufficient light resistance to some extent, so even if it is included, it is possible to use an ultraviolet absorber that does not have a yellow tint and has an absorption on the shorter wavelength side than those described above. However, of course, it is preferable to include an ultraviolet absorber to further improve the light resistance.

However, when an ultraviolet absorber is contained,
Depending on the intensity of the thermal energy when the protective layer is thermally transferred, the ultraviolet absorber and the metal source may cause a chelation reaction, and the ultraviolet absorber may have a longer wavelength up to the visible light region. Had been lost.
That is, the value of b ^* in the L ^* a ^* b ^* color system specified in JIS-Z8730 or the like has shifted in the positive direction. When an ultraviolet absorber having an absorption wavelength also in the visible light region was used, the yellowish tint became stronger and was not practically usable.

In the case of the post-chelation method, it is necessary to apply a certain amount of heat energy after dye transfer (post-heating) to promote the chelation reaction in order to obtain a performance satisfying image storability. However, if the thermal energy is applied too much, the above-mentioned problem occurs, and the coloring and the image storage performance are incompatible.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide quality, storage stability,
An object of the present invention is to provide a thermal transfer recording method having excellent durability.

[0014]

The above object of the present invention is attained by the following constitutions.

1. An ink layer of an ink sheet having at least one ink layer containing a heat-diffusible dye on a support; and an image-receiving sheet having at least one image-receiving layer capable of receiving the heat-diffusible dye on a support. The image-receiving layers are superposed so as to face each other, and are heated imagewise with a thermal head, so that the heat-diffusible dye is transferred to the image-receiving layer.
In the thermal transfer recording method in which at least one thermal transferable protective layer is provided by a thermal head, at least one layer in the protective layer contains an ultraviolet absorber, and no dye is transferred after the protective layer is transferred. The relationship between the b ^* value (b ₂ ) of the region and the b ^* value (b ₁ ) of the region where the dye has not been transferred before the transfer of the protective layer is b ₂ −b ₁ ≦ 2. Thermal transfer recording method.

2. _2. The thermal transfer recording method according to the above 1, wherein b2 is 0 or less. 3. 2. The thermal transfer recording method according to the above item 1, wherein the thermal transferable protective layer comprises at least a transparent resin layer and an adhesive layer.

4. 4. The thermal transfer recording method according to the above item 3, wherein the adhesive layer contains an ultraviolet absorber.

5. The ink layer contains a heat-diffusible dye capable of chelation, and the image-receiving layer contains a metal ion-containing compound capable of performing a chelate reaction with the heat-diffusible dye. Any one of 1-4
The thermal transfer recording method according to the item.

6. An ink layer of an ink sheet having at least one ink layer containing a heat-diffusible dye on a support; and an image-receiving sheet having at least one image-receiving layer capable of receiving the heat-diffusible dye on a support. The image-receiving layers are superposed so as to face each other, and are heated imagewise with a thermal head, so that the heat-diffusible dye is transferred to the image-receiving layer.
In a print obtained by providing at least one heat transferable protective layer with a thermal head, the b ^* value (b ₂ ) of the area where the dye has not been transferred after the transfer of the protective layer and the b ^* value (b ₂ ) of the area before the transfer of the protective layer A printed matter, wherein the relationship of b ^* value (b ₁ ) in the area where the dye is not transferred is b ₂ −b ₁ ≦ 2.

[7] FIG. printed matter according to the 6, characterized in that b ₂ is less than or equal to zero. 8. When xenon light having an irradiation energy of 400 kJ / m ² (integrated value at 420 nm) is exposed to a neutral patch having an optical density of 1.0 ± 0.1, the difference ΔE between the chromaticity before and after exposure is ΔE. ^* The print according to the above item 6, wherein ab is 10 or less.

9. When a neutral patch having an optical density of 2.0 ± 0.1 is stored for one year in an environment without light at 65 ° C. and 50% RH, the acutance value after storage is 90% or more of that before storage. 7. The printed matter according to the above item 6, wherein

10. The ink layer contains a heat-diffusible dye capable of chelation, and the image receiving layer contains a metal ion-containing compound capable of performing a chelate reaction with the heat-diffusible dye. 6. The printed matter according to 6.

Hereinafter, the present invention will be described in more detail. As described above, the cause of coloring when using the post-chelate method is that the ultraviolet energy and the metal source undergo a chelate reaction due to the heat energy at the time of transfer of the protective layer, and the ultraviolet light has a long wavelength up to the visible light region. It is considered to be.

By paying attention to this point, the present inventor has determined that the reaction between the ultraviolet absorber and the metal source does not occur, or if the reaction does not affect the printed image, the thermal head during the transfer of the protective layer. By controlling the surface temperature, the area b ^* (b ₂ ) where the dye has not been transferred after the transfer of the protective layer
And the difference between the b ^* values (b ₁ ) of the same area before printing can be reduced.

Here, the b ^* value and the color difference ΔE ^* a to be described later
The b value is JIS-Z that specifies the display method of the color difference of the surface color.
According to the L ^* a ^* b ^* color system such as 8730.

By controlling the difference in b ^* value between the area where the dye is not transferred after the transfer of the protective layer and the same area before printing to 2 or less, the influence of coloring due to the longer wavelength of the ultraviolet absorber is visually observed. Above is quite inconspicuous. Furthermore, even a difference of b ^* value is 2 or less, the b ₂ is felt as visually the yellowish when there is tinged with 0 or more, and a b ₂ are 0 or less.

During the actual transfer, it is difficult to measure the surface temperature of the thermal head when it is in contact with the protective layer transfer sheet, and the exact temperature is not known. Thermal head surface temperature is 50
When applying the applied voltage so that it is near 0 degrees,
If the phenomenon of lengthening becomes remarkable, the effect of the present invention can be obtained by controlling the thermal head so that the temperature does not become 500 degrees, for example, 450 degrees or more.

The thermal head controls the amount of heat generated by changing the voltage application time with low voltage driving using a heating element having a high electric resistance. At that time, the thermal head generates pulses of heat in accordance with the applied power.

In the control of the thermal head, pulse energy is normally turned on / off during one driving cycle as shown in FIG. During ON, the head surface temperature increases, and during OFF, the head surface temperature drops to the temperature before ON. The provision of the cooling time prevents the transfer of excess dye due to the residual heat of the head in the data portion in the next cycle.

In actual control, in order to prevent the temperature from rising due to heat storage, the voltage applied to the head is divided into a plurality of fine pulses (hereinafter referred to as reference pulses) instead of one large pulse. It is usually common. FIG.
In this case, a 0.5 ms pulse is subdivided into, for example, a 5 μs reference pulse, and a 100 pulse voltage is applied.

Incidentally, originally, due to the relationship between the power supply capacity, the head 1
It is not practical to drive the entire line (for example, 2000 or more heating elements) at the same time. Usually, a head of one line is divided into two to eight parts and a plurality of image data are simultaneously processed and recorded for each block. To go. Here, for the sake of simplicity, the description is based on simultaneous driving. However, it goes without saying that the division may be performed simultaneously as described above.

When the protective layer is transferred, the above-described process is usually used in many cases. In this case, the head surface temperature is not increased to a temperature higher than the temperature at which the wave lengthening occurs as described above. It is necessary to control

In order to prevent the head surface temperature from rising above a certain level, the present inventors control the reference pulse, specifically, turn off the pulse at appropriate intervals to achieve the object of the present invention. Achieved. For example, by repeating the application of a voltage to a reference pulse of 5 μs 100 times, a pulse of 0.5 ms in total is turned off every time (ie, the total ON time is 0.25 ms). From the 51st time onwards, instead of 5μs ON, 3
By controlling such that μs ON / 2 μs OFF (that is, the total ON time is 0.4 ms), it is possible to suppress the increase in the wave length.

The number of times of turning off, the temporal position, and the interval are as follows.
It is appropriately determined by the transferability of the protective layer and the reactivity of the post-chelating dye with the metal source, that is, the image storability. That is, even if the control does not increase the wave length, it is necessary to apply a sufficient applied energy to a level that can satisfy the adhesiveness and image storability of the protective layer.
Their performance cannot be satisfied and is not preferred.

The present inventors have determined that the level which can satisfy image storability is sufficient.
The light resistance and heat resistance do not fall below the performance below
The control conditions were studied as follows. That is, in light fastness,
Illuminate a neutral patch with an optical density of 1.0 ± 0.1
Irradiation energy 400kJ / m ^Two(Integration at 420nm
Xenon light), the chromaticity before and after exposure
Color difference ΔE^*ab is 10 or less, heat resistance
A neutral patch with an optical density of 2.0 ± 0.1
For 1 year in an environment without light at 65 ° C and 50% RH
When saving for a while, the acutance value after saving is
On the other hand, it is determined to be 90% or more.

Here, the light fastness was tested using a xenon fade meter under the following conditions. And light resistance tester: manufactured by Atlas Ci 65 - Light source: Xenon lamp Filter: Internal = IR filter, outer = soda-lime glass Black panel temperature: 25 ° C., irradiation intensity: 1.2 W / m ² (measured at 420nm Value) For heat resistance, PLATINOS manufactured by TABAI
RAINBOW PR-3G was used.

The acutance value was determined by the following method. That is, a patch of 2 cm × 2 cm was prepared, and the reflection density of the edge portion in the main scanning direction and / or sub-scanning direction was measured with a microdensitometer (PDM-5, manufactured by Konica Corporation). Is converted into an acutance value using the following equation (sampling length 5000 μm =
5 mm, sampling pitch 10 μm, aperture size 10 μm × 500 μm). This operation is performed before and after storage, and the value after storage is normalized with the value before storage.

[0038]

(Equation 1)

Where D90 = 0.90Dmax + 0.10Dmin D10 = 0.10Dmax + 0.10Dmin ΔDi: difference between adjacent density measurement values ΔXi: measurement pitch n _(D90−D10) : number of measurement points between Xi and Xf The above relationship is shown in FIG.

In the present invention, the transfer of the protective layer is carried out by using a thermal head. In this case, the same thermal head as that for dye transfer may be used, or another thermal head may be provided for transfer of the protective layer. May be.

Next, a specific example of the protective layer transfer sheet used in the present invention will be described with reference to FIG.

In FIG. 3, the protective layer transfer sheet of the specific example has a transparent resin layer 2L releasably provided on a support 1L, and a heat-sensitive adhesive layer 5L further provided thereon.
Reference numeral 3L denotes a release layer, which has an effect of lowering the adhesiveness between the transparent resin layer and the support and facilitating the transfer of the transparent resin layer. This layer 3L is unnecessary when the peelability between the support and the transparent resin layer is excellent. 4L is a back layer, which has an action of preventing adhesion to a thermal head of the printer. This layer 4L is also unnecessary when the heat resistance and slip property of the support are good.

As the support 1L, the same support as that used in a conventional ink sheet for a heat-diffusible dye can be used as it is, and other supports can be used. Not done. Specific examples of preferred support 1L include, for example, heat-resistant materials such as thin paper such as condenser paper, glassine paper, and paraffin paper, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ketone, and polyether sulfone. Polyester, polypropylene, polycarbonate, cellulose acetate, polyethylene derivatives, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide,
Examples include stretched or unstretched films of plastics such as polyimide, polymethylpentene, and ionomer, and laminates of these materials.

The thickness of the support 1L can be appropriately selected depending on the material so that the strength, heat conductivity, heat resistance and the like are appropriate. Usually, a thickness of about 1 to 100 μm is preferably used. Can be When the support has poor adhesion to a layer formed on the surface, it is preferable to apply a primer treatment or a corona treatment to the surface.

The transparent resin layer 2L provided on the support 1L comprises:
Various resins excellent in friction resistance, solvent resistance, water resistance, transparency, hardness, etc., for example, polyethylene resin, polystyrene resin, acrylic resin, polyurethane resin, acrylic urethane resin, silicon-modified resin of these resins and these A mixture of each resin and the like can be mentioned. Although these resins are excellent in transparency, they tend to form relatively tough films, and film breakage during transfer cannot be said to be sufficient, so silica, calcium carbonate, plastic pigment, etc. May be added to such an extent that the transparency of the resin is not impaired.

The method for forming the transparent resin layer 2L on the support 1L or on the release layer 3L previously provided thereon is as follows.
A gravure coat, a gravure reverse coat, a roll coat, a method of applying and drying a paint containing the above resin by various means, and the like can be mentioned. The thickness of the transparent resin layer 2L is preferably about 0.1 to 20 μm.

When the transparent resin layer is formed, by adding an additive such as a lubricant to the transparent resin layer, it is possible to improve the scratch resistance, gloss and the like of various images to be coated.

Prior to the formation of the transparent resin layer, the release layer 3L, which may be formed on the surface of the support, is formed of a release agent such as waxes, silicone wax, silicone resin, fluororesin, and acrylic resin. The forming method may be the same as the method for forming the transparent resin layer, and the thickness is 0.05 to 5 μm.
A degree is enough. If a matte protective layer is desired after transfer, the surface can be made mat-like by incorporating various particles in the release layer or by using a support having a matte surface on the release layer side. I can do it.

Further, a heat-sensitive adhesive layer 5L is provided on the surface of the transparent resin layer in order to improve the transferability of these layers. These heat-sensitive adhesive layers are, for example, coated with a solution of a resin having good adhesiveness when heated such as an acrylic resin, a polyvinyl chloride resin, a polyvinyl acetate resin, a vinyl chloride-vinyl acetate copolymer resin, and a polyester resin. By drying, it is preferably formed to a thickness of about 0.1 to 10 μm.

Preferred heat-sensitive adhesives have a Tg (glass transition temperature) of 40 to 75 ° C., more preferably a Tg of 60 to 7
It is a thermoplastic resin at 0 ° C. and has a polymerization degree of 50 to 30.
0, more preferably 50 to 250 polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride / vinyl acetate copolymer resin.

At least one of the heat transferable protective layers, ie, at least one of the transparent resin layer and the heat-sensitive adhesive layer,
It is preferable that an ultraviolet absorber is contained, but when it is contained in the transparent resin layer, the transparent resin layer is present on the outermost surface of the print after transfer of the protective layer, so that it is affected by the environment for a long time. Since the effect thereof decreases with the elapse of time, it is particularly preferable to include it in the heat-sensitive adhesive layer.

Examples of the ultraviolet absorber include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers. Specific examples thereof include Tinuvin P, Tinuvin 234, Ti
Nuvin 320, Tinuvin 326, Tin
uvin 327, Tinuvin 328, Tinu
Vin 312, Tinuvin 315 (manufactured by Ciba-Geigy), Sumisorb-110, Sumisor
b-130, Sumisorb-140, Sumiso
rb-200, Sumisorb-250, Sumis
orb-300, Sumisorb-320, Sumi
sorb-340, Sumisorb-350, Sum
isorb-400 (manufactured by Sumitomo Chemical Co., Ltd.), Mar
k LA-32, Mark LA-36, Mark 1
413 (manufactured by Adeka Argus Chemical Co., Ltd.) or the like, and any of them can be used in the present invention.

Also, a random copolymer having a Tg of 60 ° C. or higher, preferably 80 ° C. or higher, in which a reactive ultraviolet absorber and an acrylic monomer are randomly copolymerized, can be used.

The above-mentioned reactive UV absorbers include conventionally known non-reactive UV absorbers such as salicylic acid type, benzophenone type, benzotriazole type, cyanoacrylate type, nickel chelate type and hindered amine type.
It is also possible to use those into which an addition polymerizable double bond such as a vinyl group, an acryloyl group or a methacryloyl group, or an alcoholic hydroxyl group, an amino group, a carboxyl group, an epoxy group, an isocyanate group, or the like is introduced. Specifically, UVA635L, UVA633L (manufactured by BASF Japan Ltd.), PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.)
And the like, and can be used in the present invention.

The amount of the reactive ultraviolet absorber in the random copolymer of the reactive ultraviolet absorber and the acrylic monomer as described above is 10 to 90% by mass, preferably 30 to 7%.
The range is 0% by mass. Further, the molecular weight of such a random copolymer can be about 5,000 to 250,000, preferably about 9000 to 30,000.

The above-mentioned ultraviolet absorber and the random copolymer of the reactive ultraviolet absorber and the acrylic monomer may be contained alone or in combination. The amount of the random copolymer of the reactive ultraviolet absorber and the acrylic monomer is 5 to 5 parts per layer.
It is preferable to contain it in the range of 50% by mass.

Of course, other light stabilizers may be contained in addition to the ultraviolet absorber. Here, the light-fastening agent is an agent that absorbs or blocks the action of altering or decomposing the dye, such as light energy, heat energy, or oxidizing action, to prevent the alteration or decomposition of the dye. In addition to the antioxidant, there may be mentioned an antioxidant and a light stabilizer which are conventionally known as additives for synthetic resins. In this case as well, at least one of the heat transferable protective layers, that is, at least one of the release layer, the transparent resin layer, and the heat-sensitive adhesive layer may be contained, but particularly preferably, it is contained in the heat-sensitive adhesive layer.

Examples of the antioxidant include phenol-based, monophenol-based, bisphenol-based and amine-based primary antioxidants, and sulfur-based and phosphorus-based secondary antioxidants. Also, examples of the light stabilizer include hindered amines.

The use amount of the above-mentioned light-proofing agent containing an ultraviolet absorber is not particularly limited, but is preferably 0.05 to 10 parts by mass, preferably 3 to 10 parts by mass per 100 parts by mass of the resin forming the layer to be contained. Used in parts by mass. If the amount is too small, it is difficult to obtain the effect as a light-fastening agent, while if it is too large, it is uneconomical.

Further, in addition to the above-mentioned light-fastening agent, various additives such as a fluorescent whitening agent and a filler can be simultaneously added to the adhesive layer in an appropriate amount.

Protective Layer The protective layer of the transfer sheet may be provided alone on the support, or may be provided face-sequentially with the ink layer of the ink sheet described later.

An embodiment in which the protective layer is supplied in a face-sequential manner with the ink layer of the ink sheet will be described with reference to the drawings. FIG. 4 is a diagram showing an ink sheet according to one embodiment of the present invention. In FIG. 4A, yellow (Y), magenta (M), and cyan (C) ink layers 2 are provided on the same plane of a support 3 in a plane-sequential manner. A protective layer 1 in which an adhesive layer is laminated in this order is provided. In FIG. 4, no gap is provided between the respective layers, but a gap may be appropriately provided in accordance with the control method of the thermal transfer recording apparatus. Further, in order to accurately locate each layer, it is preferable to provide a detection mark on the ink sheet, but the method of providing the detection mark is not particularly limited.
In a, the ink layer and the protective layer are provided on the same plane of the support, but needless to say, each may be provided on a separate support as shown in FIG. In addition, as for the definition of the ink layer, when a post-chelate dye is used, the dye itself contained in the ink layer is a compound before the reaction, and strictly speaking, it cannot be said that the dye is Y, M, or C dye.
Y, M, and C images are similarly expressed for the sake of convenience in terms of layers for finally forming the images.

As the thermal transfer recording apparatus used in the present invention, for example, an apparatus as shown in FIG. 5 can be used. In FIG. 5, reference numeral 10 denotes an ink sheet supply roll;
5 is an ink sheet, 11 is an ink sheet 15 used
, A thermal head 13, a platen roller 13, and an image receiving sheet 14 inserted between the thermal head 12 and the platen roller 13.

In order to form an image using, for example, the ink sheet shown in FIG. 4A as an ink sheet using the thermal transfer recording apparatus shown in FIG. 5A, first, an area 2Y containing a yellow dye of the ink sheet and the image receiving The yellow dye in the ink layer in the area is transferred to the image receiving sheet according to image data by applying heat from the thermal head to form a yellow image, and then the magenta dye is formed on the yellow image. Similarly, the magenta dye is transferred imagewise from the ink layer of the region 2M containing the dye, and then the cyan dye is transferred imagewise similarly from the ink layer of the region 2C containing the cyan dye on the transferred image. Finally, the protective layer 1 is transferred to the entire surface of the image,
Image formation is completed.

FIG. 5B shows a case where the ink sheet is in the form of FIG. 4B. In this case, first, in a dye transfer apparatus, the area 2Y containing the yellow dye of the ink sheet and the image receiving layer of the image receiving sheet are overlapped, and the yellow dye in the ink layer in the area is applied to the image data by applying heat from a thermal head. To the image receiving sheet to form a yellow image, and then transfer the magenta dye imagewise from the ink layer in the area 2M containing the magenta dye onto the yellow image in the same manner. Similarly, the cyan dye is transferred imagewise from the ink layer in the area 2C containing the cyan dye to form a dye-transferred image, and finally, the protective layer 1 Is transferred to complete the image formation.

FIG. 5C shows a case where the ink sheets are separated for each color and are recorded by the corresponding devices. In this case, first, the dye on the yellow ink sheet is transferred to the image receiving sheet according to the image data to form a yellow image by the Y transfer device, and then the magenta ink sheet is formed on the yellow image by the M transfer device. The above dye is similarly transferred imagewise, and then the dye on the cyan ink sheet is transferred on the image to the image receiving sheet according to the image data by the C transfer device. Finally, FIG. As in the case described above, the protective layer 1 is transferred to the entire surface of the image by the protective layer transfer device, and the image formation is completed.

In the specific example, the order of printing is Y →
M → C → protective layer, but is not limited to this. For example, BK between the cyan ink layer and the protective layer
(Black) layer may be provided, and printing may be performed in the order of Y → M → C → BK → protective layer.
It may be changed as appropriate, such as M and Y.

Next, the ink sheet used in the present invention will be described. In the present invention, the ink sheet is formed at least from a support and an ink layer provided thereon, and the ink layer contains a heat diffusing dye.

The support for the ink sheet is not particularly limited as long as it has good dimensional stability and can withstand the heat at the time of recording with a thermal head, and any known support can be used. It is possible to use the same protective layer transfer sheet as described above.

As the binder for the ink layer, any conventionally known binders can be used. For example, cellulose-based, polyacrylic acid-based, polyvinyl alcohol-based, polyvinylpyrrolidone-based water-soluble polymers, acrylic resins, methacrylic resins, etc. , Polystyrene, polycarbonate, polysulfone, polyethersulfone, polyvinylbutyral, polyvinylacetal, ethylcellulose, nitrocellulose, and other organic solvents. Among these, polyvinyl butyral, polyvinyl acetal, or a cellulosic resin having excellent storage stability is preferable.

When a polymer soluble in an organic solvent is used,
One or more of them may be used in the form of a latex dispersion as well as being dissolved in an organic solvent. The amount of the binder resin used is 0.1 g per 1 m ² of the support.
~ 50 g is preferred. The various binders described above are
The species can be used alone, or two or more thereof can be used in combination.

As the heat diffusing dye to be contained in the ink layer used in the present invention, conventionally known dyes can be used, and there is no particular limitation. From the viewpoint of obtaining good image storability, a post-chelating dye is used. It is preferable to use

The post-chelating dye is not particularly limited as long as thermal transfer is possible, and various known compounds can be appropriately selected and used. Specifically, for example, JP-A-59-78893, JP-A-59-109349,
JP-A-4-89292, JP-A-4-94974, JP-A-4-94972
For example, cyan dyes, magenta dyes, and yellow dyes described in No. 97894 and the like can be used.

Among the above dyes, it is preferable to use a methine dye capable of forming a bidentate chelate with a metal source because the object of the present invention is more effectively exhibited. Examples of such a dye include a dye represented by the following general formula (1).

[0075]

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Wherein X is a chelate of at least bidentate
Represents a group of atoms having a possible group or atom, wherein Y is aromatic
Lists the atoms required to form a neutral carbocyclic or heterocyclic ring.
Then R ₁, R_TwoAnd R_ThreeRepresents a hydrogen atom and a halogen atom, respectively.
Or, it represents a monovalent substituent. n represents 0, 1 or 2
You. Y is preferably a 5- to 6-membered aromatic carbocyclic ring or
A group of atoms forming an elementary ring, on which a substituent is further added.
May have.

X is particularly preferably represented by the following general formula (2).

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In the formula, Z represents an atom group necessary for forming an aromatic nitrogen-containing heterocyclic ring substituted with at least one group containing a chelatable nitrogen atom.

Specific examples of the above-mentioned aromatic carbocycle and heterocycle include benzene, pyridine, pyrimidine, furan, thiophene, thiazole, imidazole and naphthalene. These rings may form a conjugation ring with another carbon ring (such as a benzene ring) or a heterocyclic ring (such as a pyridine ring).

The substituent on the ring includes an alkyl group, an aryl group, an acyl group, an amino group, a nitro group, a cyano group,
Examples thereof include an acylamino group, an alkoxyl group, a hydroxyl group, an alkoxycarbonyl group, and a halogen atom, and these groups may be further substituted.

The halogen atom represented by R ₁ , R ₂ and R ₃ is a fluorine atom, a chlorine atom and the like, and the monovalent substituent is an alkyl group, an alkoxyl group, a cyano group and an alkoxycarbonyl group. No.

As X =, those represented by the following general formulas (3) to (6) are particularly preferred.

[0084]

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In the formula, R ₄ and R ₅ are each a hydrogen atom, a halogen atom (such as a fluorine atom, a chlorine atom, or a bromine atom) or a monovalent substituent (an alkyl group, an aryl group, an acyl group, an amino group, a nitro group). Group, cyano group, acylamino group, alkoxyl group, hydroxyl group, alkoxycarbonyl group, etc.). Q represents an atom group necessary for forming a nitrogen-containing heterocyclic ring.

Hereinafter, specific examples of the compounds will be shown, but the present invention is not limited thereto.

[0087]

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[0088]

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[0089]

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[0090]

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The amount of the post-chelating dye used in the present invention is usually 0.1 g to 1 m ^{2 of the} solid content of the dye.
20 g is preferable, and 0.2 g to 5 g is more preferable. In the ink layer, any conventionally known release agent may be added or a release layer may be provided in order to prevent thermal fusion between the ink layer binder and the image receiving layer resin at the time of printing. As the release agent, various waxes such as polyethylene wax and paraffin wax, higher fatty acid alcohols, organopolysiloxanes, various surfactants, various phosphates, fluorine resins, silicone resins and the like can be used. The amount of the release agent used is preferably 0.5 to 40% by mass based on the solid content of the layer to be contained. When a release layer is provided, the same binder as that used for the dye layer can be used.

It is also preferable to provide a back layer for imparting heat resistance on the surface of the support opposite to the surface on which the dye layer is provided.

The binder resin used for the back layer is, for example, a cellulose resin such as ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, cellulose butyrate, or nitrified cotton; polyvinyl alcohol; polyvinyl acetate;
Vinyl resins such as polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, etc., acrylic resins such as polymethyl methacrylate, polyethyl acrylate, polyacrylamide, acrylonitrile / styrene copolymer, polyamide resin, vinyl toluene resin, cumarone indene resin , Polyester resin, polyurethane resin,
Examples include a silicone knit urethane resin and a fluorine-modified urethane resin.

These resins may be used as a mixture. In order to further increase the heat resistance of the back layer, a resin having a reactive group such as a hydroxyl group among the above-mentioned resins may be used, and a polyisocyanate or the like may be used as a cross-linking agent to form a cross-linked resin layer. Further, in order to improve the slipperiness with a heating means such as a thermal head, a solid or liquid release agent or lubricant may be added to the back layer so as to have heat-resistant lubrication. Examples of the release agent or lubricant include various waxes such as polyethylene wax and paraffin wax, higher aliphatic alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Agents, fluorinated surfactants, organic carboxylic acids and their derivatives, fluorinated resins,
Fine particles of an inorganic compound such as a silicone resin, talc, silica, and molybdenum sulfide can be used. The preferable addition amount of the lubricant to the back layer is 5 to 50% by mass, particularly preferably 10 to 30% by mass, based on the total solid content of the back layer.
% By mass. The thickness of the back layer is 0.1 to
About 10 μm is preferable.

The ink sheet is prepared by dispersing or dissolving the above-mentioned various components for forming an ink layer in a solvent to prepare an ink layer forming coating liquid, and applying the coating liquid on the surface of the ink sheet support, for example, by gravure printing. It can be manufactured by coating and drying in a system. The thickness of the ink layer to be formed is usually from 0.2 to 10 μm, preferably from 0.3 to 3 μm.

Next, the image receiving sheet used in the present invention will be described. The image receiving sheet of the present invention comprises at least a support and an image receiving layer formed on the surface of the support.

The support of the image receiving sheet preferably has a role of holding the image receiving layer and has a mechanical strength that does not hinder handling even in a heated state since heat is applied during thermal transfer. . The material of such a support is not particularly limited. For example, condenser paper, glassine paper, sulfuric acid paper, synthetic paper (polyolefin-based, polystyrene-based), 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 internal paper, paperboard, etc., cellulose fiber paper, or polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene Vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyetheretherketone, polysulfone, polyethersulfone, tetra Films such as fluoroethylene / perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride, and the like, and these synthetic resins In order to enhance the sharpness of an image formed in a later step, a white pigment or a filler (for example, titanium white, magnesium carbonate, zinc oxide, barium sulfate, silica, talc, clay, calcium carbonate, etc.) is added. A filmed white opaque film or a foamed foam sheet can also be used and is not particularly limited.

Further, a laminate obtained by combining any of the above supports can also be used as the support. As an example of a typical laminate, there is a synthetic paper of cellulose fiber paper and synthetic paper or a synthetic paper of cellulose fiber paper and plastic film. The above materials may be further laminated on the synthetic paper or plastic film in order to separate functions such as cushioning property and heat conductivity. The thickness of the support may be arbitrarily determined according to the intended use, and usually about 10 to 300 μm is used.

In order to have higher printing sensitivity and to obtain high image quality without density unevenness or white spots, it is preferable to have a layer having fine voids in the support. As the layer having fine voids, a plastic film or synthetic paper having fine voids inside can be used. Also,
A layer having fine voids can be formed on various supports by various coating methods. As a plastic film or synthetic paper having fine voids, a polyolefin, particularly polypropylene, is mainly used, and an inorganic pigment and / or a polymer incompatible with polypropylene is blended with the plastic film. These are used as a void (void) forming initiator. A plastic film or synthetic paper obtained by stretching and forming a mixture of the above is preferred. When these are mainly composed of polyester, etc., the viscoelastic or thermal properties thereof, the cushioning properties, and the heat insulation properties are inferior to those mainly composed of polypropylene, so that the printing sensitivity is inferior. Density unevenness is also likely to occur.

In consideration of these points, the elastic modulus of plastic film and synthetic paper at 20 ° C. is 5 × 10 ⁸
Pa to 1 × 10 ¹⁰ Pa is preferable. Further, since these plastic films and synthetic papers are usually formed by biaxial stretching, they shrink by heating. When these are left at 110 ° C. for 60 seconds, the shrinkage is 0.5 to 2.5%. The above-mentioned plastic film or synthetic paper may itself be a single layer including layers having fine voids, or may have a multilayer structure.

In the case of a plurality of layers, all the constituent layers may contain fine voids, or may contain a layer having no fine voids. If necessary, a white pigment may be mixed into the plastic film or synthetic paper as a concealing agent. Further, in order to increase whiteness, an additive such as a fluorescent whitening agent may be contained. The layer having fine voids preferably has a thickness of 30 to 80 μm.

A layer having fine voids can be formed on a support by a coating method. As the plastic resin to be used, known resins such as polyester, urethane resin, polycarbonate, acrylic resin, polyvinyl chloride, and polyvinyl acetate can be used alone or as a blend of two or more. As the support, various types of paper, synthetic paper, nonwoven fabric, plastic film, and the like described above can be used.

If necessary, polyvinyl alcohol, polyvinylidene chloride, polyethylene, polypropylene, modified polyolefin, polyethylene terephthalate, polycarbonate may be provided on the surface of the support opposite to the side on which the image receiving layer is provided, for the purpose of curling prevention. Or a layer of resin or synthetic paper. As a bonding method,
For example, known lamination methods such as dry lamination, non-solvent (hot melt) lamination, and EC lamination can be used, and preferred methods are dry lamination and non-solvent lamination. Examples of an adhesive suitable for the non-solvent lamination method include Takenate 720L manufactured by Takeda Pharmaceutical Co., Ltd., and examples of an adhesive suitable for dry lamination include Takelac manufactured by Takeda Pharmaceutical Co., Ltd. A969 / Takenate A-5 (3/1), Polysol PSA SE-140, manufactured by Showa Polymer Co., Ltd.
0, vinylol PSA AV-6200 series and the like. The amount of these adhesives used is about 1 to 8 g / m ² , preferably ² to 6 g / m ² in solid content.

When the plastic film and the synthetic paper, or the plastic film and the synthetic paper, etc., or various kinds of paper and the plastic film or the synthetic paper are laminated as described above, they can be bonded with an adhesive layer.

When the adhesion between the support and the layer provided thereon is poor, it is preferable to apply various primer treatments or corona discharge treatment to the surface of the support.

The image receiving layer is formed from the ink layer of the ink sheet.
There is no particular limitation as long as it can receive the dye diffused by heating, and it is basically formed of a binder and various additives. As a method of forming an image receiving layer on the surface of a support, a coating solution for an image receiving layer is prepared by dispersing or dissolving a component for forming an image receiving layer in a solvent, and the coating solution for an image receiving layer is coated on the support. Or a coating method in which the mixture having the components for forming the image receiving layer is melt-extruded and then laminated on the surface of the support. The thickness of the image receiving layer formed on the surface of the support is generally 0.5 to 50 μm, preferably 1 to 50 μm.
It is about 20 μm.

As the binder for the image receiving layer, various binders such as a vinyl chloride resin, a polyester resin, a polycarbonate resin, an acrylic resin, a polyvinyl acetal resin and various heat resistant resins can be used. The type of the binder may be selected arbitrarily, but polyvinyl acetal-based resin or vinyl chloride-based resin is preferable in terms of image storability. Examples of the polyvinyl acetal resin include a polyvinyl acetoacetal resin, a polyvinyl butyral resin, and a polyvinyl formal resin. Examples of the vinyl chloride resin include a polyvinyl chloride resin and a vinyl chloride copolymer. Examples of the vinyl chloride copolymer include a copolymer of vinyl chloride and another comonomer containing vinyl chloride at a ratio of 50 mol% or more as a monomer unit. In addition to the polyvinyl acetal resin and the vinyl chloride resin, a polyester resin can also be suitably used as the image receiving layer for thermal transfer. Examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, and compounds described in JP-A-58-188695 and JP-A-62-244696. Also,
Examples of polycarbonate resins include, for example,
Various compounds described in 2-169694 can be used.

As the acrylic resin, for example, polyacrylester can be mentioned. As the heat-resistant resin, it is not a resin having an excellent heat resistance and an extremely low softening point or a glass transition point (Tg). Heat resistant resins can be used. "Heat resistance" here
This means that the resin itself does not cause coloring such as yellowing when stored under heat, and the physical strength does not extremely deteriorate. The heat-resistant resin has a softening point of 30 to 200 ° C.,
g is preferably from 50 to 150 ° C. Softening point is 30
When the temperature is lower than 0 ° C., it is not preferable because the ink sheet and the image receiving layer may be fused when transferring the heat transferable dye. If the softening point exceeds 200 ° C., the sensitivity of the image receiving layer is undesirably lowered. Examples of the heat-resistant resin satisfying the above conditions include a phenol resin, a melamine resin, a urea aldehyde resin, and a ketone resin. Among them, a urea aldehyde resin and a ketone resin are particularly preferable. Urea aldehyde resin is obtained by condensation of urea and aldehydes (mainly formaldehyde), and ketone resin is obtained by condensation reaction of ketone and formaldehyde.

In a preferred embodiment of the present invention, when a post-chelate dye is contained in the ink layer, a metal source capable of forming a metal chelate with the post-chelate dye is contained in the image receiving layer.

Examples of the metal source include inorganic or organic salts and metal complexes of metal ions, and among them, salts and complexes of organic acids are preferable. As the metal, the I-th of the periodic table
Monovalent and polyvalent metals belonging to Groups VIII to VIII, among which Al, Co, Cr, Cu, Fe, Mg, M
n, Mo, Ni, Sn, Ti and Zn are preferred, and particularly Ni, Cu, Cr, Co and Zn are preferred. Specific examples of the metal source include Ni ²⁺ , Cu ²⁺ , Cr ²⁺ , Co
^Examples include ²⁺ and Zn ²⁺ and an aliphatic salt such as acetic acid and stearic acid, or a salt of an aromatic carboxylic acid such as benzoic acid and salicylic acid. Further, the complex represented by the following general formula (7) is particularly preferable because it is stable and can be added to the image receiving layer and is substantially colorless.

Formula (7) [M (Q₁)_X(Q_Two)_Y(Q_Three)_Z]^{P +}(L^-)_P In the general formula (7), M is a metal ion, preferably Ni²⁺,
Cu²⁺, Cr²⁺, Co ²⁺Or Zn²⁺Represents Q₁, Q_TwoPassing
And Q_ThreeIs capable of coordinating with a metal ion represented by M
Coordination compounds, which are the same but different
Is also good. These coordination compounds include, for example, chelates
From coordination compounds described in Science (5) (Nankodo)
You can choose. L^-Represents an organic anion group,
Specifically, tetraphenyl boron anion or alkyl
And benzenesulfonic acid anion. X
Represents 1, 2 or 3, Y represents 1, 2 or 0, and Z represents
Represents 1 or 0, which is represented by the general formula (7)
Depends on whether the complex is tetradentate or hexadentate
Or Q₁, Q_Two, Q_ThreeDetermined by the number of ligands
It is. P represents 1 or 2. This kind of metal sauce ingredients
As a body example, US Pat. No. 4,987,049 is described.
Or Japanese Patent Application Laid-Open No. 9-39423.
Compounds MS-1 to 99 exemplified in this document
Can be.

The amount of the metal source to be added is usually preferably from 5 to 80% by mass based on the binder of the image receiving layer.
70 mass% is more preferable. If the amount of the metal source in the image receiving layer is too large, the tint of the metal source appears in the color tone of the white background of the image receiving sheet, which is not preferable.

It is preferable to add a release agent to the image receiving layer in order to prevent thermal fusion with the dye layer. As the release agent, a phosphate ester-based plasticizer, a fluorine-based compound, a silicone oil (including a reaction-curable silicone) and the like can be used, and among them, the silicone oil is preferable. Various modified silicones such as dimethyl silicone can be used as the silicone oil.
Specifically, amino-modified silicone, epoxy-modified silicone, alcohol-modified silicone, vinyl-modified silicone, urethane-modified silicone, or the like can be used, and these can be blended or polymerized using various reactions. One or more release agents are used. Further, the amount of the release agent to be added depends on the resin 1
0.5 to 30 parts by mass is preferable with respect to 00 parts by mass. If the addition amount is not satisfied, problems such as fusion between the thermal transfer sheet and the image receiving layer of the image receiving sheet or reduction in printing sensitivity may occur. Note that these release agents may not be added to the image receiving layer but may be separately provided on the image receiving layer as a release layer.

The above-mentioned image receiving layer is formed by coating a binder resin and a dye-fixed body with an additive such as a release agent, if necessary, and dissolving or dispersing in a solvent such as water or an organic solvent. The liquid can be formed by applying the liquid by a usual method such as a bar coater, a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, and drying. The means for forming the barrier layer, the intermediate layer, and the back surface layer, which will be described later, is performed in the same manner as in the case of the image receiving layer. In addition, the image receiving layer is formed not only by coating the coating solution directly on the support as described above and drying it, but also by forming the image receiving layer on another support in advance, The image receiving layer may be formed by transfer. Note that a similar material can be used for the above another support. The thickness of the image receiving layer is preferably about 0.1 to 10 μm in terms of the thickness after coating and drying.

At least one layer is provided between the image receiving layer and the support.
An intermediate layer having more than two layers may be provided. The intermediate layer means all layers provided between the image receiving layer and the support, such as an adhesive layer (primer layer), a barrier layer, an ultraviolet absorbing layer, a foaming layer, and an antistatic layer. Either can be used. Furthermore, it is preferable to add a white pigment such as titanium oxide to the intermediate layer in order to hide the glare and unevenness of the support, since the degree of freedom in selecting the support increases. The content of the intermediate layer resin and the white pigment is preferably from 30 to 300 parts by mass of the white pigment solid content with respect to 100 parts by mass of the resin solid content.
In order to enhance the concealing property, it is more preferable to use it in the range of 100 to 300 parts by mass.

As the intermediate layer, a layer obtained by curing a thermoplastic resin, a thermosetting resin, or a thermoplastic resin having a functional group by using various additives or other methods can be used. Specifically, polyvinyl alcohol, polyvinylpyrrolidone, polyester, chlorinated polypropylene,
Modified polyolefin, urethane resin, acrylic resin, polycarbonate, ionomer, resin obtained by curing a monofunctional and / or polyfunctional hydroxyl-containing prepolymer with isocyanate or the like can be used.

Further, a back surface layer may be provided on the surface of the support opposite to the image receiving layer in order to improve the mechanical transportability of the image receiving sheet, prevent static charge, impart writing properties, and the like. In order to improve the transportability, it is preferable to add an appropriate amount of an organic or inorganic filler to the binder resin, or to use a highly slippery resin such as a polyolefin resin or a cellulose resin. In addition, in order to obtain an antistatic function, a layer made of a conductive resin such as an acrylic resin or a conductive filler, and further a fatty acid ester, a sulfate ester, a phosphate ester,
A layer to which an antistatic agent such as amides, quaternary ammonium salts, betaines, amino acids, and ethylene oxide additions may be added may be formed.

The amount of the antistatic agent used varies depending on the layer to which the antistatic agent is added and the type of the antistatic agent. In any case, the surface electric resistance of the image receiving sheet is 10 ¹³ Ω.
/ Cm ² or less. When it is larger than 10 ¹³ Ω / cm ² , the image receiving sheets adhere to each other due to electrostatic contact,
It may cause paper feeding problems. Quantitatively 0.01 to 3.0
g / m ² is preferred. When the amount of the antistatic agent used is 0.01 g / m ² or less, the antistatic effect is insufficient. On the other hand, when the amount is 3.0 g / m ² or more, it is too uneconomical and causes problems such as stickiness. May be.

The writing layer for imparting writability includes an aqueous pen,
This is a layer provided with writeability using a ballpoint pen, a fountain pen, a pencil, or the like, or a layer provided with printing and printing aptitude, such as printing ink, inkjet ink, hot melt transfer ink, and toner. In addition, when the image receiving sheet is used as a postcard, the writing layer can be provided with adhesiveness of a stamp.
The writing layer mainly includes a binder resin and an inorganic filler. As the binder resin, for example, acrylate, saturated polyester, vinyl acetate, vinyl chloride-
Vinyl acetate copolymer, cellulose acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol and the like can be used. Examples of the inorganic filler include silica, clay, calcium carbonate, titanium oxide, and zinc oxide. The writing layer may be provided on the entire surface of the image receiving sheet,
It may be formed partially. The means for forming the writing layer may be a conventionally known print coating means. The thickness of the writing layer is 0.
It is about 5 to ²⁰ g / m ² .

The image receiving sheet according to the present invention may be supplied to the printer in sheet form or in a roll form. The term “sheet-feeding” refers to, for example, a mode in which an image receiving sheet is cut into a fixed size, about 50 sheets are put into a cassette as one set, and mounted on a printer for use. The roll form is a form in which an image receiving sheet is supplied to the printer in that form, cut into a desired size after printing, and used. In particular, the latter is preferable because troubles in the transport system such as defective paper feeding and defective discharge such as insertion of two sheets can be solved, and the capacity for printing can be increased.

When the image receiving sheet is supplied in a roll form,
In particular, when using the postcard specification as described above, or when using a label or a sticker-type image receiving sheet, cut off the design mark such as a postal code frame formed on the back side or the half cut position of the seal. A detection mark can be provided on the back surface side for alignment.

The color and shape of the detection mark need only be detectable by the detector of the printer, and are not fixed. The shape may be a square, a round, a straight line, a bar code, or the like. The detection mark may be formed over the entire width of the image receiving sheet or may be formed partially. The color of the detection mark is determined by the detector, such as black, brown, or another color, and is not limited. The method for forming the detection mark is not particularly limited, as it can be formed by gravure printing or offset printing, or a colored film with an adhesive can be attached to the back surface.

When the detection mark is formed by printing, it can be formed by an ink in which a coloring agent or an absorbing agent for controlling the reflectance (for example, an infrared absorbing agent) is dispersed in a thermoplastic resin or a thermosetting resin. . Specifically, as the colorant, inorganic pigments such as carbon black and iron tetroxide, and organic pigments such as aniline black can be used. Examples of the absorbent include organic materials such as cyanine, phthalocyanine, naphthalocyanine, naphthoquinone, anthraquinone, aminium, dithiol metal complex, diimmonium, triphenylmethane, clonic methine, azurenium, and billyllium. Is mentioned.

As the binder resin for the detection mark, a thermoplastic resin such as polyvinyl alcohol, polyvinylpyrrolidone, polyester, chlorinated polypropylene, modified polyolefin, urethane resin, acrylic resin, polycarbonate, ionomer, or a monofunctional and / or polyfunctional hydroxyl group A resin or the like obtained by dispersing a contained prepolymer and curing with an isocyanate or the like can be used. Using the above-mentioned coloring agent or absorbent and a binder, an appropriate dispersing agent (for example, a nonionic surfactant such as a fatty acid ester or a polyoxyethylene alkyl ether, or a cationic surfactant such as an alkylamine salt) is used. The detection mark can be formed by a detection mark coating liquid dispersed or dissolved in a solvent, preferably by gravure printing.

[0125]

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

Example 1 In the following examples, “parts” means “parts by mass”. << Preparation of Ink Sheet 1 >> A back layer having the following composition was provided on a non-easily adhesive surface of a 6 μm-thick polyethylene terephthalate film (6FK203E manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) having one surface subjected to an easy adhesion treatment as a support. After coating and drying by a gravure coating method, the composition was cured by heating and aging to form a back layer having a thickness of 1 μm.

<Back Layer> Polyvinyl butyral 3.6 parts (SREC BX-1 manufactured by Sekisui Chemical Co., Ltd.) Polyisocyanate 19.2 parts (Bernock D750-45 manufactured by Dainippon Ink and Chemicals, Inc.) Phosphate ester 2.9 parts (Plysurf A208S manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Phosphate ester surfactant 0.3 parts (Phosphonal RD720 manufactured by Toho Chemical Co., Ltd.) Talc 0.2 parts ( Nippon Talc Co., Ltd .: Y / X = 0.03) 33 parts of methyl ethyl ketone 33 parts of toluene
Protection layer, yellow layer, magenta layer, cyan layer, protection layer
Gravure printing is repeated in order, and then dried.
An ink sheet 1 was obtained. The amount of ink layer applied is dry
About 3g / m at time ^Two, The coating amount of the protective layer is dry
0.5g / m^Two, Transparent resin layer is 2g / m^Two, The adhesive layer is 1
g / m^TwoAnd

<Yellow ink layer> 5.5 parts of a quinophthalone-based dye represented by the following structural formula

[0129]

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4.5 parts of polyvinyl butyral (S-LEC BX-1 manufactured by Sekisui Chemical Co., Ltd.) 45 parts of methyl ethyl ketone 45 parts of toluene <Magenta ink layer> In the above yellow ink layer,
The dye was C.I. I. A magenta ink layer was obtained in the same manner except that Disperse Red 60 was used.

<Cyan Ink Layer> In the above yellow ink layer, the dye was C.I. I. Solvent Blue
A cyan ink layer was obtained in the same manner except that the composition was changed to 63.

<Protective layer> (Release layer) Alkyl vinyl ether / maleic anhydride copolymer derivative 10 parts (VEMA manufactured by Daicel Chemical Industries, Ltd.) Polyvinyl alcohol resin 2 parts (Kuraray Co., Ltd.) Water 40 parts Ethanol 60 parts (Transparent resin layer) Acrylic resin 20 parts (BR-83 manufactured by Mitsubishi Rayon Co., Ltd.) 1 part of polyethylene wax 40 parts of methyl ethyl ketone 40 parts of toluene (adhesive layer) 20 parts of vinyl chloride / vinyl acetate copolymer (Denki Kagaku Kogyo Co., Ltd. Co., Ltd. # 1000A) Additives listed in Table 1 Additives in Table 1 Microsilica 1 part Methyl ethyl ketone 40 parts Toluene 40 parts TINUVIN-328: Benzotriazole UV absorber UVA-635L: Benzophenone UV absorber acrylic Polymer PUVA-30M: Benzotria Acrylic copolymer of sol-based ultraviolet absorber << Preparation of ink sheet 2 >> In ink sheet 1, dye 26 used as a dye for yellow ink layer, compound 25 as a dye used for magenta ink layer, dye used for cyan ink layer Was changed to Exemplified Compound 28 to obtain an ink sheet 2 in the same manner. Table 2 shows the types and amounts of the additives to be added to the adhesive layer. << Preparation of Image Receiving Sheet 1 >> Synthetic paper having a thickness of 150 μm as a support (Yupo FPG-150 manufactured by Oji Yuka Synthetic Paper Co., Ltd.)
An image receiving layer having the following composition was applied to one surface of the film by a wire bar coating method so that the coating amount when dried was 4 g / m ^2, and dried at 110 ° C. for 30 seconds to obtain an image receiving sheet 1.

<Image Receiving Layer> 60 parts of vinyl chloride / vinyl acetate copolymer (# 1000A manufactured by Denki Kagaku Kogyo Co., Ltd.) 0.7 parts of epoxy-modified silicon (KF-393 manufactured by Shin-Etsu Chemical Co., Ltd.) Amino-modified silicon 0.3 parts (KF-343 manufactured by Shin-Etsu Chemical Co., Ltd.) Methyl ethyl ketone 20 parts Toluene 20 parts << Preparation of Image Receiving Sheet 2 >> Synthetic paper having a thickness of 150 μm as a support (Yupo FPG- manufactured by Oji Yuka Synthetic Paper Co., Ltd.) 150)
An image receiving layer ² was obtained by applying an image receiving layer having the following composition by wire bar coating so that the coating amount upon drying was 4 g / m ^2, and then drying at 110 ° C. for 30 seconds.

<Image receiving layer> 50 parts of vinyl chloride / vinyl acetate copolymer (# 1000A manufactured by Denki Kagaku Kogyo KK) 10 parts of the following metal source: Ni ²⁺ (CH ₃ COCH (CO ₂ C ₂ H ₅ ) COC ₇ H ₁₅₎ 0.7 parts of ₂ epoxy-modified silicone (Shin-Etsu Chemical Co., Ltd. KF-393) 0.3 parts amino-modified silicone (Shin-Etsu Chemical Co., Ltd. KF-343) Methyl ethyl ketone 20 parts toluene 20 parts "transfer Conditions >> Resolution 12 dots / mm, average resistance value 32
Using a thermal head of 00Ω, head driving cycle 5m
In s, the following six protective layer transfer conditions were set. () Is the maximum head surface temperature in a state of being in contact with room air.

(Transfer condition 1) 5 μsec ON reference pulse × 700 times (about 500 ° C.) (Transfer condition 2) 4 μsec ON reference pulse × 700 times (470 ° C.) (Transfer condition 3) 5 μsec ON reference pulse 52 times +
The reference pulse of 3 μsec ON / 2 μsec OFF is set to 18
Is repeated 10 times (at 460 ° C.) (Transfer condition 4) 35 pulses of 5 μsec ON reference pulse +
The reference pulse of 3 μsec ON / 2 μsec OFF is 35
Is repeated 10 times (at 445 ° C.) (Transfer condition 5) A reference pulse of 5 μsec ON 18 times +
The reference pulse of 3 μsec ON / 2 μsec OFF is 52
Is repeated 10 times (430 ° C.) (Transfer condition 6) A combination of 5 μON reference pulse + 5 μOFF reference pulse is repeated 350 times (400 times)
C) << Image formation >> The image receiving layer portion of the thermal transfer image receiving sheet produced in the above procedure and the ink layer portion of the ink sheet were overlapped, and pressed against a thermal head having a resolution of 12 dots / mm and an average resistance value of 3200Ω by a platen roll. ~ 80mJ / m
m ² (approximately 0.035 to 0.556 mJ / dot), yellow, magenta,
The cyan and neutral (three-color superimposed) step pattern was heated from the back side of the ink layer under the condition of a head drive cycle of 5 msec / line to transfer the dye onto the image receiving layer. Then, with the same thermal head and platen roll,
The protective layer was pressed against the dye-transferred image-receiving sheet, the above-mentioned six types of protective layer transfer conditions were appropriately selected, and the protective layer was transferred by heating from the back side of the protective layer. The created print is blurred,
No occurrence of printing omission was observed.

In order to visually observe the difference between the image receiving sheet before printing and the image receiving sheet after printing and to measure the chromaticity, the printing area was made smaller than the width of the image receiving sheet.

The following evaluations were performed on the obtained images 1 to 51. The evaluation results are shown in Tables 1 and 2.

(Evaluation of Coloring) The difference in color between a portion having no protective layer (that is, a portion where no printing was performed) and a white portion having been transferred was visually evaluated in a printed material to which only the protective layer was transferred. The worse the coloring caused by the ultraviolet absorber in the protective layer, the more the difference appears, and the image quality is deteriorated. The evaluation criteria are as follows.

：: The color difference is not recognized. Δ: The color difference can be recognized when viewed closely, but there is no practical problem. ×: The color difference appears clearly and is unsightly. At the same time, the portion where the protective layer is not transferred and the portion where the protective layer is not transferred are present. L
^* a ^* b ^* was also measured. The measurement was performed using CR-221 (manufactured by Minolta Co., Ltd.) under the conditions of a D65 light source and a 2 degree visual field. The difference between b ₂ and b ₁ was determined from the value measured here.

(Evaluation of Light Resistance) Under the above-mentioned conditions, a neutral patch having an optical density of 1.0 ± 0.1 was exposed to xenon light having an irradiation energy of 400 kJ / m ² (integrated value at 420 nm). The color difference ΔE ^* ab before and after exposure was evaluated. The measurement of L ^* a ^* b ^* was performed using CR-221 (manufactured by Minolta Co., Ltd.) under the conditions of a D65 light source and a 2 degree visual field.

(Evaluation of Heat Resistance) Under the conditions described above, a neutral patch having an optical density of 2.0 ± 0.1
The samples were stored for 1 year in an environment free from light at 50 ° C. and 50% RH, and the acutance values before and after storage were evaluated.

(Evaluation of Adhesion of Protective Layer) A grid test in accordance with JIS K 5400 was performed on the protective layer of the obtained image. Specifically, 11 cuts were made on the surface of the protective layer at 1 mm intervals vertically and horizontally, and 100 grids of 1 mm square were made. A cellophane tape was stuck thereon, peeled off quickly at an angle of 90 °, and the number of grids remaining without peeling was counted and evaluated according to the following criteria.

◎: 100 pieces (no peeling at all) ：: 90 to 99 pieces Δ: 70 to 89 pieces ×: 0 to 69 pieces Practically, △ is the lower limit.

[0144]

[Table 1]

[0145]

[Table 2]

[0146]

According to the present invention, a thermal transfer image excellent in image quality, image storability and durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an elapsed time profile of a surface temperature of a thermal head.

FIG. 2 is a diagram showing a method of measuring acutance.

FIG. 3 is a cross-sectional view showing an example of an embodiment of a protective layer used in the method of the present invention.

FIG. 4 is a plan view showing an example of an embodiment of an ink layer and a protective layer provided on an ink sheet used in the method of the present invention.

FIG. 5 is a diagram illustrating an example of a thermal transfer recording apparatus used in the present invention.

[Explanation of symbols]

 1L Support 2L Transparent resin layer 3L Release layer 4L Back layer 5L Thermal adhesive layer 1 Protective layer area 2Y Area containing yellow dye 2M Area containing magenta dye 2C Area containing cyan dye 3, 3 'Ink sheet support Body 10 Ink sheet supply roll 11 Winding roll 12 Thermal head 13 Platen roller 14 Image receiving sheet 15 Ink sheet

Claims (10)

[Claims] 1. An ink sheet having at least one ink layer containing a heat-diffusible dye on a support, and at least one image-receiving layer capable of receiving the heat-diffusible dye on the support. After superimposing the image receiving layers of the image receiving sheet having a layer so as to face each other, and heating the image with a thermal head imagewise, the heat diffusible dye is transferred to the image receiving layer.
In a thermal transfer recording method in which at least one layer of a heat transferable protective layer is provided by a thermal head on at least a region where a dye is transferred on an image receiving sheet, at least one of the protective layers contains an ultraviolet absorber, and B ^* value (b ₂ ) of the area where the dye has not been transferred after the transfer of the protective layer
And b in an area where the dye has not been transferred before the transfer of the protective layer.
^* A thermal transfer recording method, wherein the relationship of the value (b ₁ ) is b ₂ −b ₁ ≦ 2. _2. The thermal transfer recording method according to claim 1, wherein b ₂ is 0 or less. 3. The thermal transfer recording method according to claim 1, wherein the thermal transferable protective layer comprises at least a transparent resin layer and an adhesive layer. 4. The thermal transfer recording method according to claim 3, wherein the adhesive layer contains an ultraviolet absorber. 5. The ink layer contains a heat-diffusible dye capable of being chelated, and the image-receiving layer contains a metal ion-containing compound capable of undergoing a chelate reaction with the heat-diffusible dye. The method according to claim 1, wherein
The thermal transfer recording method according to the item. 6. An ink sheet of an ink sheet having at least one ink layer containing a heat-diffusible dye on a support, and at least one image-receiving layer capable of receiving the heat-diffusible dye on the support. After superimposing the image receiving layers of the image receiving sheet having a layer so as to face each other, and heating the image with a thermal head imagewise, the heat diffusible dye is transferred to the image receiving layer.
In a print obtained by providing at least one heat-transferable protective layer by a thermal head on at least the area of the image receiving sheet where the dye has been transferred, b ^{* of the} area where the dye has not been transferred after the transfer of the protective layer is obtained ^. Value (b ₂ )
And b in an area where the dye has not been transferred before the transfer of the protective layer.
^* A print, wherein the relationship of the value (b ₁ ) is b ₂ −b ₁ ≦ 2. 7. The printed matter according to claim 6, wherein b ₂ is 0 or less. 8. An irradiation energy of 400 kJ / m ² (420) is applied to a neutral patch having an optical density of 1.0 ± 0.1.
The printed matter according to claim 6, wherein when exposed to xenon light (integrated value in nm), the difference ΔE ^* ab between the chromaticity before exposure and the chromaticity after exposure is 10 or less. 9. When a neutral patch having an optical density of 2.0 ± 0.1 is stored for one year in an environment without light at 65 ° C. and 50% RH, the acutance value after storage is lower than that before storage. The print according to claim 6, wherein the print ratio is 90% or more. 10. The ink layer contains a heat-diffusible dye capable of being chelated, and the image-receiving layer contains a metal ion-containing compound capable of undergoing a chelate reaction with the heat-diffusible dye. The printed matter according to claim 6, characterized in that: