JPH04284291A - Thermal transfer recording method - Google Patents

Abstract

PURPOSE:To improve fixing property of coloring matter, transfer density, heat resistant preservative property and light resistant preservative property by making thermodiffusive coloring matter accepting property of a first image receiving layer of an image receiving sheet for thermal transfer recording larger than that of a second image receiving layer and heating the image receiving sheet after images are formed. CONSTITUTION:On a support body 1, a first image receiving layer 2 is layered and a second image receiving layer 3 is layered thereon by using a binder for image receiving layer and various additives, and thermodiffusive coloring matter accepting property of the first image receiving layer 2 is made to be larger than that of the second image receiving layer 3, so as to make an image receiving sheet 4 for thermal transfer recording. At this time, thickness of the first image receiving layer 2 is made to be about 5-20mum and thickness of the second image receiving layer 3 is made to be about 0.5-2mum. An ink layer 6 of an ink sheet 7 for thermal transfer recording and the image receiving layer 3 of the image receiving sheet 4 are superposed and heated by a thermal head 8 so as to record images. Then, the image receiving sheet 4 is put through a heat roll so as to heat from the side of the support body 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer recording method, and more particularly to a heat-sensitive transfer recording method capable of producing high-density images with excellent dye fixability, heat-resistant storage stability, and light-resistant storage stability.

0002

BACKGROUND OF THE INVENTION Conventionally, color recording techniques such as inkjet, electrophotography, and thermal transfer recording have been studied as methods for obtaining color hard copies.

Among these, the thermal transfer recording method is particularly
It has advantages such as easy operation and maintenance, miniaturization of the device, and low cost.

[0004] There are two types of this thermal transfer recording system as follows.

That is, a method in which a transfer sheet having a meltable ink layer on a support is imagewise heated with a laser or a thermal head to melt and transfer the meltable ink layer onto an image-receiving sheet for thermal transfer recording; A thermal diffusion transfer method in which a heat-sensitive transfer recording ink sheet having an ink layer containing a heat-diffusible dye (sublimable dye) on a support is used to diffusely transfer the heat-diffusible dye to an image-receiving sheet for heat-sensitive transfer recording. There are two types.

Among these, the thermal diffusion transfer method can control the gradation of the image by changing the amount of dye transferred in response to changes in the thermal energy of the thermal head, so it is possible to control the gradation of the image in cyan, magenta, and yellow. In recent years, it has been attracting attention as a method for obtaining color images with continuous changes in color shading by performing overlapping recording.

However, the conventional thermal diffusion transfer method has various problems.

For example, in conventional image-receiving sheets for thermal transfer recording, the fixability of dyes transferred from the ink sheet for thermal transfer recording during thermal transfer is not necessarily good.

[0009] Furthermore, the heat and light storage stability of the formed image is not sufficient, and especially when exposed to light or stored for a long period of time in a high temperature environment, the dye may bleed or bleed out. Therefore, it is not possible to maintain a clear, high-quality image during image formation.

[0010] In order to improve the heat-resistant storage stability of the image, a resin film is laminated to the image-receiving sheet for thermal transfer recording with an image formed thereon via an adhesive layer, or an image-receiving layer having a single layer structure is laminated with a resin film. Some measures have been taken to heat-treat image-receiving sheets for thermal transfer recording that have a There is a problem that sufficient effects cannot be obtained.

The present invention has been made to improve the above situation. That is, an object of the present invention is to provide a heat-sensitive transfer recording method capable of producing high-density images with excellent dye fixability, heat-resistant storage stability, and light-resistant storage stability.

0012

[Means for Solving the Problems] The present invention for achieving the above object comprises laminating a first image receiving layer and a second image receiving layer in this order on a support, and The image-receiving sheet for thermal transfer recording is heated by overlapping and heating the image-receiving sheet for thermal transfer recording whose diffusible dye receptivity is larger than the thermal diffusible dye receptivity of the second image-receiving layer. This is a heat-sensitive transfer recording method characterized by forming an image by transferring a heat-diffusible dye onto a sheet, and then heat-treating an image-receiving sheet for heat-sensitive transfer recording having this image.

(1) Image-receiving sheet for thermal transfer recording The image-receiving sheet for thermal transfer recording of the present invention is basically formed by laminating a first image-receiving layer and a second image-receiving layer in this order on a support.

-Support- Examples of the support include paper, coated paper, synthetic paper (polypropylene, polystyrene, or a composite material made of paper or plastic film), white polyethylene terephthalate base film, transparent polyethylene terephthalate. Examples include base film, white polyvinyl chloride base film, polyolefin-coated paper, and the like.

[0015] The thickness of the support is usually 20 to 1000 μm.
, preferably 50 to 800 μm.

-Image-receiving layer- Both the first image-receiving layer and the second image-receiving layer can be formed from an image-receiving layer binder and various additives.

In some cases, the first image-receiving layer and the second image-receiving layer can be formed using only the binder for the image-receiving layer.

In the present invention, the receptivity of the first image-receiving layer to the heat-diffusible dye is superior to the receptivity of the second image-receiving layer to the heat-diffusible dye.

However, the "thermally diffusible dye receptivity" referred to in the present invention can be evaluated by the following measuring method.

[0020] A coating solution is prepared by mixing various resin binders and dyes to be described later in a ratio (weight ratio) of 100:1, and this coating solution is applied onto a support so that the dry film thickness is 4.
A first colored layer is provided by coating and drying to a thickness of μm, and then a coating liquid prepared with a resin binder different from that of the first colored layer and the dye used in the first colored layer is applied onto the dried film. A second colored layer is provided by laminated coating and drying to a thickness of 4 μm.

The colored layer laminated as above was heated to 100° C. and left for 24 hours, then sliced into 3 μm thick slices in the direction perpendicular to the lamination direction, and the cross section was observed with a microtome to determine the degree of coloration of the dye. The acceptability of the resin binder is determined by

[0022] Also, the additives described below are judged using the same method.

When the receptivity of the heat-diffusible dye in the first image-receiving layer is superior to the receptivity of the heat-diffusible dye in the second image-receiving layer, the image-receiving sheet for thermal transfer recording has a high fixability of the heat-diffusible dye. , image preservability, and ability to prevent bleeding of heat-diffusible dyes can be improved.

[0024] Such an effect becomes even more remarkable by introducing heat treatment after image formation, which will be described later.

[0025] In order to differentiate the receptivity of the first image-receiving layer and the second image-receiving layer to heat-diffusible dyes as described above, appropriate additives may be used from among the binders and additives for the image-receiving layer described below. What is necessary is to select the materials, adjust their blending amounts, the thickness of the image-receiving layer, etc.

1. Binders for image-receiving layers The binders for image-receiving layers used in the present invention include, for example, polyvinyl chloride resins, copolymer resins of vinyl chloride and other monomers (for example, alkyl vinyl ether, allyl glycidyl ether, vinyl propionate, etc.), polychlorinated resins, etc. Vinylidene resin, polyester resin, acrylic ester, methacrylic ester, polyvinylpyrrolidone, polycarbonate, polysulfone, polyarylate, polyparabanic acid, cellulose triacetate, styrene acrylate resin, vinyltoluene acrylate resin, polyurethane resin, polyamide resin, urea resin, Examples include polycaprolactone resin, styrene-maleic anhydride resin, polyacrylonitrile resin, epoxy resin, and phenoxy resin.

These resins can be used alone or in combination of two or more.

The various resins mentioned above may be newly synthesized and used, but commercially available products may also be used.

In any case, from the viewpoint of physical properties, resins with glass transition points (Tg) in the range of -20 to 150°C, particularly 30 to 150°C, are suitable as binders for the image-receiving layer.
Preferably, the resin has an Mw in the range of 2,000 to 100,000.

[0030] In forming the image-receiving layer, the above-mentioned various resins utilize their reactive active sites (if there are no reactive active sites, they are added to the resin), and radiation, heat, moisture, and catalysts are used to form the image-receiving layer. It may be crosslinked or cured by, for example.

In that case, a radiation active monomer such as epoxy or acrylic, or a crosslinking agent such as isocyanate can be used.

Among the above resins, examples of resins having excellent dye-receptivity include polyvinyl chloride resins, polyvinylidene chloride resins, polyolefin resins, cellulose resins, polyester resins, (meth)acrylic resins,
Examples include polyamide resin, epoxy resin, polyvinyl alcohol, and the like.

Further, examples of resins having relatively poor dye-receiving ability include polyvinyl chloride, polysulfone, polycarbonate, polyarylate, silicone resin, and fluorine resin.

However, the above classification depends on the quality of the resin itself, and in the case of copolymers, it varies greatly depending on the type of monomers to be copolymerized, the monomer ratio, and the method of modifying the copolymer.

Furthermore, when considered as an image-receiving layer, it largely depends on the additives described below, and it is not necessarily necessary to determine the binders for the first and second image-receiving layers based on the above-mentioned difference in receiving ability.

2. Additives A release agent, an antioxidant, a UV absorber, a light stabilizer, a filler (inorganic fine particles, organic resin particles), and a pigment may be added to the additive image-receiving layer. Furthermore, a plasticizer, a hot solvent, etc. may be added as a sensitizer.

The release agent is used to improve the releasability between the ink sheet for thermal transfer recording and the image-receiving sheet for thermal transfer recording, and in the present invention, it is particularly preferably added to the second image-receiving layer.

Such release agents include silicone oil (including what is called silicone resin); solid waxes such as polyethylene wax, amide wax, and Teflon powder; fluorine-based and phosphoric acid ester-based surfactants; Among them, silicone oil is preferred. This silicone oil is a simple addition type (
There are two types: the simple addition type) and the curing or reaction type (hardening reaction type).

In the case of the simple addition type, it is preferable to use a modified silicone oil (for example, polyester modified silicone resin, urethane modified silicone resin, acrylic modified silicone resin, etc.) in order to improve the compatibility with the binder.

[0040] The amount of these simple addition type silicone oils cannot be uniformly determined because it may vary depending on the type of silicone oil, but generally speaking, the amount of the binder for the image-receiving layer The amount is 0.1 to 50% by weight, preferably 0.5 to 20% by weight.

[0041] As curing reaction type silicone oil,
Examples include reaction curing type (for example, reaction curing of amino-modified silicone oil and epoxy-modified silicone oil), photo-curing type, catalyst curing type, and the like.

The amount of these curable silicone oils added is preferably 0.5 to 30% by weight of the binder for the image-receiving layer.

[0043] A release agent layer can also be provided on a part of the surface of the image-receiving layer by dissolving or dispersing the above-mentioned release agent in a suitable solvent and applying the solution, followed by drying.

[0044] Next, as the antioxidant, JP-A-59
-182785 publication, 60-130735 publication,
Antioxidants described in JP-A-1-127387, etc.
and compounds known to improve image durability in photographs and other image recording materials.

[0045] The UV absorber and light stabilizer include:
JP-A-59-158287, JP-A No. 63-74686
No. 63-145089, No. 59-196
Publication No. 292, Publication No. 62-229594, 63-1
Compounds described in JP-A No. 22596, JP-A No. 61-283595, JP-A-1-204788, etc., and compounds known to improve image durability in photographs and other image recording materials can be mentioned.

[0046] Examples of the filler include inorganic fine particles and organic resin particles.

Examples of the inorganic fine particles include silica gel, calcium carbonate, titanium oxide, acid clay, activated clay, alumina, etc., and examples of the organic fine particles include fluororesin particles, guanamine resin particles, acrylic resin particles, silicone resin particles, etc. The following resin particles can be mentioned. These inorganic/organic resin particles vary depending on the specific gravity, but are between 0 and 3.
Addition of 0% by weight is preferred.

Typical examples of the pigment include titanium white, calcium carbonate, zinc oxide, barium sulfate, silica, talc, clay, kaolin, activated clay, and acid clay.

[0049] As the plasticizer, phthalate esters,
Trimellitic acid esters, adipic acid esters, other saturated or unsaturated carboxylic acid esters, citric acid esters, epoxidized soybean oil, epoxidized linseed oil, epoxy stearic acid esters, orthophosphoric esters, phosphorous acid Examples include esters and glycol esters.

In the present invention, the total amount of additives added is usually in the range of 0 to 30% by weight based on the binder for the image-receiving layer.

-Other Layers- An intermediate layer (subbing layer) may be provided between the image-receiving layer and the support for the purpose of imparting properties such as heat insulation, barrier properties, cushioning properties, and adhesive properties.

Further, an overcoat layer may be laminated on the surface of the image-receiving layer for the purpose of preventing fusion between the ink sheet for thermal transfer recording and the image-receiving sheet for thermal transfer recording. Furthermore, a backing layer may be provided on the surface opposite to the image-receiving layer (support surface) for the purpose of preventing charging, curling, and the like.

(2) Production of an image-receiving sheet for thermal transfer recording An image-receiving sheet for thermal transfer recording is prepared by dispersing or dissolving the components for forming the image-receiving layer in a solvent to prepare a coating liquid for the image-receiving layer. It can be formed by a coating method in which a coating liquid is applied to the surface of a support and dried, or a lamination method in which a mixture containing the components for forming the image-receiving layer is melt-extruded and laminated on the surface of the support.

Solvents used in the above coating method include water, alcohols (for example, ethanol, propanol), cellosolves (for example, methyl cellosolve, ethyl cellosolve), aromatics (for example, toluene, xylene, chlorobenzene), ketones (for example, Examples include acetone, methyl ethyl ketone), ester solvents (eg, ethyl acetate, butyl acetate, etc.), ethers (eg, tetrahydrofuran, dioxane), chlorine solvents (eg, chloroform, trichlorethylene), and the like.

[0055] For the coating, conventionally known coating methods using a gravure roll, extrusion coating method, wire bar coating method, roll coating method, etc. can be employed.

The image-receiving layer may be formed over the entire surface of the support, or may be formed on a part of the surface.

In the present invention, there are preferable conditions regarding the thickness of the image-receiving layer.

That is, the thickness of the first image-receiving layer is preferably 3 μm or more, preferably 5 to 20 μm, and the thickness of the second image-receiving layer is preferably less than 3 μm, preferably 0.5 to 2 μm. If the thickness of the first image-receiving layer is less than 3 μm, the ability to retain the heat-diffusible dye may be insufficient and image preservation may deteriorate; if the thickness of the second image-receiving layer exceeds 3 μm, the heat-diffusible dye This is because, like the former, sufficient image preservation may not be obtained due to insufficient diffusion of the image.

(3) Ink sheet for thermal transfer recording An ink sheet for thermal transfer recording is basically formed by laminating ink layers on a support.

-Support- The support used in the present invention may be anything as long as it has good dimensional stability and can withstand the heat during recording with a thermal head, such as condenser paper or glassine paper. Tissue paper, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polycarbonate,
polysulfone, polyvinyl alcohol, cellophane,
A heat resistant plastic film such as polystyrene can be used.

The thickness of the support is preferably 2 to 10 μm. The shape of the support is not particularly limited, and may be of any shape, such as a wide sheet or film, or a narrow tape or card.

-Ink layer- The ink layer contains a heat-diffusible dye and a binder as essential components.

1. Heat-diffusible dyes Examples of heat-diffusible dyes include cyan dyes, magenta dyes, and yellow dyes.

[0064] As the cyan dye, JP-A-59-7
No. 8896, No. 59-227948, No. 60-249
No. 66, No. 60-53563, No. 60-130735
No. 60-131292, No. 60-239289, No. 61-19396, No. 61-22993, No. 6
No. 1-31292, No. 61-31467, No. 61-3
No. 5994, No. 61-49893, No. 61-1482
No. 69, No. 62-191191, No. 63-91288
Examples include naphthoquinone dyes, anthraquinone dyes, and azomethine dyes described in publications such as No. 63-91287 and No. 63-290793.

As a magenta dye, JP-A-59-7
No. 8896, JP-A-60-30392, JP-A-60-
No. 30394, JP-A No. 60-253595, JP-A-Sho 6
Anthraquinone dyes and azo Examples include dyes, azomethine dyes, and the like.

[0066] As a yellow dye, JP-A-59-78
No. 896, JP-A-60-27594, JP-A-60-3
No. 1560, JP-A-60-53565, JP-A-61-
Examples include methine dyes, azo dyes, quinophthalone dyes, and anthrisothiazole dyes described in publications such as No. 12394 and JP-A-63-122594.

Particularly preferred as the heat-diffusible dye is a compound having an open-chain or closed-chain active methylene group, an oxidized product of a p-phenylenediamine derivative, or a p-phenylenediamine derivative.
- Azomethine dye obtained by a coupling reaction with an oxidized product of an aminophenol derivative and indoaniline obtained by a coupling reaction with an oxidized product of a phenol or naphthol derivative or a p-phenylenediamine derivative or an oxidized product of a p-aminophenol derivative. It is a pigment.

The heat-diffusible dye contained in the ink layer may be any of yellow, magenta, and cyan dyes as long as the image to be formed is monochromatic.

[0069] Depending on the tone of the image to be formed, it may contain two or more of the above three types of dyes or other heat-diffusible dyes.

The amount of the heat-diffusible dye used is usually 0.1 to 5 g, preferably 0.2 to 2 g per 1 m 2 of the support.
It is g.

2. Binder: As a binder for the ink layer, a cellulose addition compound,
Cellulose resins such as cellulose ester and cellulose ether; polyvinyl alcohol, polyvinyl formal, polyvinyl acetoacetal, polyvinyl acetal resins such as polyvinyl butyral, polyvinylpyrrolidone, polyvinyl acetate, polyacrylamide, styrene resin, poly(meth)acrylic acid type Examples include vinyl resins such as esters, poly(meth)acrylic acid, and (meth)acrylic acid copolymers, rubber resins, ionomer resins, olefin resins, and polyester resins.

Among these resins, polyvinyl butyral, polyvinyl acetoacetal or cellulose resins are preferred because of their excellent storage stability.

[0073] The above-mentioned various binders can be used singly or in combination of two or more.

The weight ratio of the binder to the heat-diffusible dye is preferably 1:10 to 10:1, particularly preferably 2:8 to 7:3.

3. Other Optional Components Furthermore, various additives may be appropriately added to the ink layer.

The additives include silicone resin, silicone oil (reactive curing type is also possible), silicone modified resin, fluororesin, surfactant, and peeling compounds such as waxes, fine metal powder, silica gel, and metal oxide. Examples include fillers such as carbon black and fine resin powder, and curing agents that can react with binder components (for example, radiation active compounds such as isocyanates, acrylics, and epoxies).

Furthermore, examples of additives include heat-melting substances for promoting transfer, such as waxes and higher fatty acid esters, which are described in JP-A-59-106997.

-Other Layers- The ink sheet for thermal transfer recording is not limited to a two-layer structure consisting of a support and an ink layer, and other layers may be formed.

For example, an overcoat layer may be provided on the surface of the ink layer for the purpose of preventing fusion with the image-receiving sheet for thermal transfer recording and setting-off (blocking) of the heat-diffusible dye.

The support may also have a subbing layer for the purpose of improving adhesion to the binder and preventing transfer and dyeing of the dye to the support.

Furthermore, the back side of the support (the side opposite to the ink layer)
A backing layer may be provided for the purpose of running stability, heat resistance, antistatic properties, etc.

[0082] The thickness of the overcoat layer, undercoat layer and backing layer is usually 0.1 to 1 μm.

(4) Manufacture of ink sheet for thermal transfer recording The ink sheet for thermal transfer recording is prepared by preparing a coating liquid for forming an ink layer by dispersing or dissolving the various components forming the ink layer in a solvent. , coat this on the surface of the support,
It can be manufactured by drying.

[0084] The above-mentioned binders are used by dissolving one or more of them in a solvent or dispersing them in a latex form.

Examples of the solvent include water, ethanol, tetrahydrofuran, methyl ethyl ketone, toluene, xylene, chloroform, dioxane, acetone, cyclohexane, n-butyl acetate, and the like.

[0086] For the above-mentioned coating, conventional methods such as a surface sequential coating method using a gravure roll, an extrusion coating method, a wire bar coating method, a roll coating method, etc. can be employed.

The ink layer may be formed as a layer containing a single color heat-diffusible dye on the entire surface or a part of the surface of the support, or may be formed as a layer containing a monochromatic heat-diffusible dye, or a yellow ink layer containing a binder and a yellow dye. A magenta ink layer containing a binder and a magenta dye and a cyan ink layer containing a binder and a cyan dye are formed on the entire surface or a part of the surface of the support in a constant repetition along the plane direction. You can leave it there.

[0088] In addition to the three ink layers arranged in the plane direction, a black ink layer containing a black image forming substance may be interposed.

[0089] Regarding the black ink layer, clear images can be obtained with either the diffusion transfer type or the melt transfer type.

The thickness of the ink layer thus formed is usually 0.2 to 10 μm, preferably 0.3 to 3 μm.
It is μm.

[0091] The ink sheet for thermal transfer recording may be provided with perforations or detection marks for detecting the positions of areas with different hues to facilitate use.

(5) Thermal transfer recording method To form an image, the ink layer of the ink sheet for thermal transfer recording and the image receiving layer of the image receiving sheet for thermal transfer recording are overlapped, and an image is formed on the interface between the ink layer and the image receiving layer. Gives heat energy to Wise.

The heat-diffusible dye in the ink layer vaporizes or sublimates in an amount corresponding to the thermal energy applied during image formation, and is transferred to and received by the image-receiving layer, resulting in the formation of an image on the image-receiving layer. Ru.

Although an image is formed on the image-receiving layer, if the image-receiving layer has a two-layer structure, the concentration of the heat-dissipating dye is higher in the second image-receiving layer than in the first image-receiving layer. is normal.

Therefore, in the present invention, in order to diffuse the heat-diffusible dye present in the second image-receiving layer to the first image-receiving layer side as much as possible, the heat-diffusible dye receptivity of the first image-receiving layer is adjusted in advance to the second image-receiving layer. After increasing the size of the layer, the image-receiving sheet for thermal transfer recording on which the image has been formed is further heat-treated.

As described above, when heat treatment is performed after image formation under the condition that the heat-diffusible dye receptivity of the first image-receiving layer is greater than that of the second image-receiving layer, the concentration of the heat-diffusible dye in the first image-receiving layer decreases. This not only increases the fixing properties of the heat-diffusible dye, but also prevents the dye from blurring or bleeding out due to light or heat, thereby improving the heat-resistant storage stability and light-resistant storage stability of the image.

[0097] As the heat treatment means, known means can be used, such as heat rolls and hot stamps which are commonly used, as well as heat sources to be described later used during image formation, such as thermal heads, laser beams, etc. , an infrared flash, a thermal pen, etc. can also be used.

Among these heat sources, when using a thermal head, an ink sheet for thermal transfer recording with an area without an ink layer or another sheet for heat treatment is used to protect the head. Preferably, the image-receiving sheet for thermal transfer recording having an image is heat-treated.

In any case, since the dye is diffused toward the first image-receiving layer, it is necessary to supply sufficient thermal energy to the first image-receiving layer. The heating during the heat treatment may be performed from the surface side of the image receiving layer (the surface side of the second image receiving layer), the support side, or both sides thereof, but for efficient heat treatment, it is preferable to heat from the support side.

[0100] The heating temperature and heating time of the heat treatment vary depending on the heat source, but any of the heat sources used when recording an image as described below can be used, and the heat treatment can be carried out within the range of normal image recording.

[0101] When a heat roll is used for the heat treatment, the heating temperature is usually 70 to 200°C, preferably 100°C.
~150°C, and the conveying speed is usually
0.01-20mm/sec, preferably 0.05-5mm
/second. Further, when a hot stamp is used for the heat treatment, the heating temperature is usually in the range of 50 to 200°C, preferably 80 to 150°C, and the pressure is usually in the range of 0.
05-20Kg/cm2, preferably 0.5-5Kg
/cm2, and the heating time is usually 0.1 to 20 seconds, preferably 0.5 to 10 seconds.

[0102] By the way, a thermal head is generally used as a heat source for providing the thermal energy applied during image formation, but other sources include laser light, infrared flash,
A known device such as a thermal pen can be used.

When using the above thermal head, the applied thermal energy can be varied continuously or in multiple stages by modulating the voltage or pulse width applied to the thermal head.

[0104] When using the laser beam, the thermal energy provided can be varied by changing the amount of laser light and the irradiation area.

[0105] In this case, in order to facilitate the absorption of laser light, it is preferable to make a laser light absorbing material (for example, in the case of a semiconductor laser, carbon black or a near-infrared absorbing substance) exist in the ink layer or near the ink layer. .

When using a laser beam, it is preferable to bring the ink sheet for thermal transfer recording and the image-receiving sheet for thermal transfer recording into close contact with each other.

[0107] If a dot generator incorporating an acousto-optic element is used, thermal energy can be applied depending on the size of halftone dots.

[0108] When using the infrared flash lamp, heating is preferably performed through a black or colored layer containing an infrared absorbing substance, as in the case of using laser light.

[0109] Alternatively, heating may be performed through a pattern or halftone dot pattern that continuously expresses the shading of an image, such as black, or a colored layer such as black on one side and a negative of the above pattern. Heating may be performed in combination with negative patterns. Thermal energy may be applied during image formation from the ink sheet side for thermal transfer recording, from the image receiving sheet side for thermal transfer recording, or from both sides, but effective use of thermal energy If priority is given to this, it is desirable to carry out the process from the ink sheet side for thermal transfer recording.

[0110] By the above thermal transfer recording, a one-color image can be recorded on the image-receiving layer of an image-receiving sheet for thermal transfer recording, but according to the method described below, it is possible to obtain a color photographic color image consisting of a combination of each color. You can also do it.

[0111] For example, by sequentially replacing yellow, magenta, cyan, and, if necessary, black thermal transfer recording sheets and performing thermal transfer according to each color, a color photo-like color image consisting of a combination of each color is obtained. You can also do that.

[0112] The following method is also effective.

That is, instead of using ink sheets for heat-sensitive transfer recording of each color as described above, an ink sheet for heat-sensitive transfer recording is used which has areas pre-painted in each color.

[0114] First, the yellow area is used to thermally transfer the yellow color separation image, and then the magenta area is used to thermally transfer the magenta color separation image. , and, if necessary, a method of thermally transferring the black color image in this order.

[0115] Although it is possible to obtain a color photographic-like color image with this method as well, a further advantage of this method is that there is no need to replace the heat-sensitive sheet for heat-sensitive transfer recording as described above. There is.

[0116] In addition, when the heat treatment is performed using a thermal head, an ink sheet for thermal transfer recording, which has areas pre-painted in each color as described above, is further provided with an area to which no ink layer is attached. This eliminates the problem of preparing separate sheets for heat treatment.

[0117]

EXAMPLES Next, the present invention will be explained in more detail based on examples. Note that in the following, "parts" represent "parts by weight."

(Example 1) A coating solution for forming an ink layer having the following composition was dried by a wire bar coating method on the corona-treated surface of a 6 μm thick polyethylene terephthalate film [manufactured by Toray Industries, Inc.] as a support. After coating and drying to a thickness of 1 μm, a silicone resin [Dainichiseika Co., Ltd.
A droplet or two of a nitrocellulose solution containing SP-2105 manufactured by Co., Ltd. was applied with a dropper and spread over the entire surface, and a backside treatment coating was performed to obtain an ink sheet for thermal transfer recording.

Coating liquid for ink layer formation; Disperse dye...
・・・・・・・・・・・・4.0 copies [
Kayaset Blue 136, manufactured by Nippon Kayaku Co., Ltd.]
Polyvinyl butyral・・・・・・・・・
...4.0 parts [Sekisui Chemical Co., Ltd., S-LEC BX-1]
Methyl ethyl ketone・・・・・・・・・・・・・・・
・ Part 82 Cyclohexanone...
・・・・・・・・・・・・・・・ 10 parts Next, as a support, synthetic paper with a thickness of 150 μm [trade name Yupo FPG
-150; Manufactured by Oji Yuka Synthetic Paper Co., Ltd.] A coating liquid for forming a first image-receiving layer and a coating liquid for forming a second image-receiving layer having the following compositions were sequentially applied and dried by a coating method on the synthetic paper. An image-receiving sheet for thermal transfer recording was obtained by forming a first image-receiving layer with a thickness of 10 μm and a second image-receiving layer with a thickness of 2 μm.

Coating liquid for forming the first image-receiving layer; Vinyl chloride-isobutyl vinyl ether copolymer...9.0 parts
[Manufactured by BASF, Raroflex MP25]
Trimellitic acid alkyl ester...
......1.0 part [Adekasizer C79, manufactured by Asahi Denka Kogyo Co., Ltd.]
Methyl ethyl ketone・・・・・・・・・・・・・・・
・ 80 parts cyclohexanone...
・・・・・・・・・・・・・・・ 10 parts
Coating liquid for forming second image-receiving layer; Polyvinyl chloride...
・・・・・・・・・・・・9.5 parts [manufactured by Shin-Etsu Chemical Co., Ltd., TK600] Polyester modified silicone resin・・・・・・・・・0
．． 5 parts [manufactured by Shin-Etsu Silicone Co., Ltd.,
- 24- 8300] Methyl ethyl ketone 80 parts
Cyclohexanone・・・・・・・・・
...... 10 copies Next, the ink sheet for thermal transfer recording and the image receiving sheet for thermal transfer recording,
The former ink layer surface and the latter image-receiving layer surface are overlapped so that they are in contact with each other, and a thermal head is used to print an output of 0.4 W/dot, a pulse width of 0.3 to 10 msec, and a dot from the support side of the ink sheet for thermal transfer recording. Density 6 dots/m
Image recording was performed by heating under the conditions of m.

After recording the image, the image-receiving sheet for thermal transfer recording having the image on the image-receiving layer is heated on a heat roll (heating temperature: 130°C).
) at a conveyance speed of 0.1 mm/sec from the support side.

The transfer density on the surface of the image-receiving layer, the heat and light storage stability of the image, the dye fixing property and the bleeding prevention property were evaluated according to the following criteria. The results are shown in Table 1.

Transfer density: Reflection density OD value was measured using an optical densitometer. ◎...OD value is 2.5 or more〇...OD value is 2.0-2.5 △...OD value is 1.7-2.0 X...OD value is 1.7 or less.

Heat resistance (heat-resistant image storage stability): The image-receiving sheet for thermal transfer recording on which an image has been recorded is stored at 77°C and relative humidity 80%.
The specimens were kept in this environment for 72 hours, and the presence or absence of dye bleed-out and color change or fading (judged visually) was examined. ○...The pigment does not easily come off even if you rub the image with your hands. There is also no discoloration or fading.

X: When the image was rubbed by hand, the dye was removed, or discoloration or fading was observed.

Light Resistance (Light Resistance Image Preservability) The image-receiving sheet for thermal transfer on which the image was recorded was exposed to light for 72 hours using a xenon weather meter, and then the image was visually judged. ○: No discoloration or fading of the pigment is observed. ×: Significant discoloration or fading of pigment.

Dye fixability: The image-receiving sheet for thermal transfer recording with an image recorded thereon faced the image-receiving sheet for thermal transfer recording on which no image was recorded, a load of 40 g/cm2 was applied, and the sheet was left at 60° C. for 48 hours. The judgment was made based on the transfer density of the dye transferred to the image-receiving sheet for thermal transfer recording on which no image was recorded. ◎・・・The transferred dye density was less than 0.10. Good: The transferred dye density was 0.10 to 0.15. x: The transferred dye density was 0.15 or more.

Prevention of dye bleeding: The image-receiving sheet for thermal transfer recording on which an image was recorded was left at 60° C. for one week, and then the degree of dye bleeding was visually judged. ○: Almost no bleeding is observed. ×: Bleeding was observed. (Example 2) The same procedure as in Example 1 was carried out except that the composition of the second image-receiving layer forming coating liquid was changed to the following composition.

Coating liquid for forming second image-receiving layer: Vinyl chloride-benzyl methacrylate copolymer: 9.5 parts
[Vinyl chloride content; 83.7%, Tg; 51
°C] Polyester modified silicone resin 0.5 part [manufactured by Shin-Etsu Silicone Co., Ltd., X-24-8300]
Methyl ethyl ketone・・・・・・・・・・・・
・・・・・・ 80 parts Cyclohexanone ・・・・・・・・・・・・・・・ 10 parts.

(Example 3) Except that in Example 1, instead of the heat treatment using a heat roll performed after image formation, energy was applied to the entire image forming area using a thermal head to perform heat treatment. A thermal transfer recording method was carried out in the same manner as in Example 1.

This thermal transfer recording method is schematically shown in FIG. 1 (cross-sectional view). That is, first there is an image receiving sheet 4 for thermal transfer recording having a first image receiving layer 2 and a second image receiving layer 3 on a support 1 in this order, and an image receiving sheet 4 for thermal transfer recording having an ink layer 6 on a support 5. The ink sheet 7 is connected to the image receiving layer 3 and the ink layer 6.
(A), and heated using a thermal head 8 from the support 5 side.

[0132] The ink sheet 7 for thermal transfer recording is as follows:
When viewed from above, it has a structure in which regions of the ink layer 6 and regions of the support 5 are exposed alternately, as shown in the plan view of FIG.

When heated as described above, the heat-diffusible dye 9 in the ink layer 6 migrates to the second image-receiving layer 3 and first image-receiving layer 2 side, forming an image there. At this time, the concentration of the heat-diffusible dye 9 is higher in the second image-receiving layer 3 than in the first image-receiving layer 2 (B).

In this state, when heat treatment is then performed using the same thermal head 8 through the area where the support 5 of the ink sheet 7 for thermal transfer recording is exposed, the thermal diffusivity in the second image receiving layer 3 increases. The dye 9 migrates to the first image-receiving layer 2 side, and as a result,
The concentration of the thermally diffusible dye 9 in the first image-receiving layer 2 increases (C).

(Example 4) In Example 1, instead of the heat treatment using a heat roll performed after image formation, a hot stamp (heating temperature 140°C, pressure 1.5 kg/cm2) was used.
, heating time 5 seconds) except that the heat treatment was performed in Example 1.
I did the same thing.

[0136] This thermal transfer recording method is also similar to Examples 1 to 3 above.
Similarly, since the image-receiving layers are laminated so that the dye-receiving ability of the first image-receiving layer is superior to that of the second image-receiving layer, the heat-diffusible dye in the second image-receiving layer can be heated by hot stamping. As a result, the heat-diffusible dye is transferred to the first image-receiving layer side, and as a result, the concentration of the heat-diffusible dye in the first image-receiving layer becomes high.

(Example 5) The composition of the image-receiving and forming coating liquid was changed to the one shown below, and instead of the heat treatment using a heat roll performed after image formation in Example 1, an infrared flash lamp was irradiated from the support side. The same procedure as in Example 1 was carried out except that the heat treatment was performed.

Coating liquid for forming the first image-receiving layer; Vinyl chloride-isobutyl vinyl ether copolymer...8.9 parts
[Manufactured by BASF, Raroflex MP25]
Trimellitic acid alkyl ester...
......1.0 part [Adekasizer C79, manufactured by Asahi Denka Kogyo Co., Ltd.]
Infrared absorber・・・・・・・・・・・・・・・・・・
・0.1 part [Nippon Kayaku Co., Ltd., Kayasorb CY-9] Methyl ethyl ketone 80 parts
Cyclohexanone・・・・・・・・・・・・
... 10 copies
Coating liquid for forming a second image-receiving layer;
PVC·················
・9.5 parts [manufactured by Shin-Etsu Chemical Co., Ltd.]
TK600] Polyester modified silicone resin 0.5 part
[Manufactured by Shin-Etsu Silicone Co., Ltd., X-24-8300
] Infrared absorber・・・・・・・・・
・・・・・・・・・0.01 part [Kayasorb CY-9 manufactured by Nippon Kayaku Co., Ltd.]
Methyl ethyl ketone・・・・・・・・・・・・・・・
80 parts cyclohexanone...
・・・・・・・・・・・・・ 10 copies This thermal transfer recording method is also similar to Examples 1 to 4 above, so that the dye-receiving ability of the first image-receiving layer is superior to that of the second image-receiving layer. An image-receiving layer is laminated thereon. Additionally, since each layer contains an infrared absorbing material, it efficiently converts light irradiation from an infrared flash lamp into thermal energy. Furthermore, since the amount of infrared absorbing material contained in the first image receiving layer is greater than that contained in the second image receiving layer, the first image receiving layer is better in terms of thermal efficiency. Therefore, the first image receiving layer side is heated more than the second image receiving layer side. As a result, the heat-diffusible dye in the second image-receiving layer migrates to the first image-receiving layer side by heat treatment using an infrared flash lamp, and as a result, the concentration of the heat-diffusible dye in the first image-receiving layer increases.

(Comparative Example 1) Except that the coating solution for forming the second image-receiving layer of Example 1 was used instead of the coating solution for forming the first image-receiving layer of Example 1 to form the first image-receiving layer. The same thermal transfer recording method as in Example 1 was carried out.

(Comparative Example 2) A thermal transfer recording method was carried out in the same manner as in Example 1 except that the heat treatment performed after image formation was omitted.

[0141]

[Table 1]

[0142]

Effects of the Invention The heat-sensitive transfer recording method of the present invention makes the heat-diffusible dye receptivity of the first image-receiving layer of the image-receiving sheet for heat-sensitive transfer recording greater than that of the second image-receiving layer, and allows Since the image-receiving sheet for thermal transfer recording is heat-treated, the dye fixability and
The transfer density is improved, the storage stability of the image against heat and light is improved, and it is possible to provide a high-quality image in which dye bleeding is prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the thermal transfer recording method of the present invention.

FIG. 2 is a schematic plan view of an ink sheet for thermal transfer recording used in the present invention.

[Explanation of sign]

1 Image-receiving sheet support for thermal transfer recording 2 First image-receiving layer 3 Second image-receiving layer 4 Image-receiving sheet for thermal transfer recording 5 Ink sheet support for thermal transfer recording 6 Ink layer 7 Ink sheet for thermal transfer recording 9 heat diffusible dye

Claims (1)

[Claims] Claim 1: A first image-receiving layer and a second image-receiving layer are laminated in this order on a support, and the heat-diffusible dye-receptivity of the first image-receiving layer is higher than that of the second image-receiving layer. By overlapping and heating an image receiving sheet for thermal transfer recording which is larger than the size of the image receiving sheet for thermal transfer recording and heating it, a thermally diffusible dye is transferred to the image receiving sheet for thermal transfer recording to form an image. A thermal transfer recording method, which comprises heat-treating an image-receiving sheet for thermal transfer recording having this image.