JPH11227345A - Heat transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer image receiving sheet for improving a chelation rate of a heat diffusion dye stuff by reducing a coating cost and improving an operating environment. SOLUTION: The heat transfer image receiving sheet comprises at least two image receiving layers formed by water coating on a support in such a manner that a lower layer of the receiving layers contains a metallic ion containing compound for forming a chelate in reaction with a heat diffusion dye. In preferred embodiments, the metallic ion-containing compound is a water soluble compound, contains a release agent in addition to the ion-containing compound. And, the two or more layers of the receiving layers are formed by simultaneous water double coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving sheet for thermal transfer, and more particularly, to an image receiving sheet for thermal transfer capable of reducing the coating cost and improving the working environment during manufacturing.

[0002]

2. Description of the Related Art In thermal transfer recording of a thermal diffusion transfer system, a dye used in a thermal transfer recording material is important.
Conventional dyes have the disadvantage that the stability of the obtained images, that is, the light fastness and the fixability, are poor.

[0003] In order to improve these drawbacks,
JP-A-59-78893, JP-A-59-109394,
JP-A-60-2398 and the like disclose an image forming method for forming an image on a thermal transfer recording image-receiving sheet (hereinafter referred to as an image-receiving sheet) using a chelatable dye by using a heat-diffusable dye capable of being chelated. It has been disclosed.

[0004] However, these image forming methods are excellent methods for improving heat resistance and fixing property. However, in the production of an image receiving sheet used for these methods, a heat diffusion dye which does not involve a chelation reaction is used. Similar to the applied binder resin, a coating solution using an organic solvent that completely dissolves the binder resin (for example, a polyester resin, a vinyl chloride resin, etc.) has been used.

When a coating solution containing an organic solvent is applied to a support to produce an image receiving sheet, the coating solution is dried to spread the vapor of the organic solvent to the workplace, thereby providing a worker with health benefits. Not only does it have a negative impact, but there is also a risk of fire explosion. Therefore, there is an urgent need to improve the working environment such as installing an exhaust duct in a work place or using an explosion-proof structure.

In some cases, prevention of bleeding of the formed image and storability of the image are not sufficient.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a thermal transfer image-receiving sheet in which the coating cost can be reduced, the working environment is improved, and the chelation rate of the heat-diffusible dye is improved.

[0008]

The above object of the present invention is achieved by the following constitution.

(1) A metal having at least two image-receiving layers formed by aqueous coating on a support, and forming a chelate by reacting with a heat-diffusable dye in a lower layer of the image-receiving layers. An image-receiving sheet for thermal transfer containing an ion-containing compound.

(2) The image receiving sheet for thermal transfer according to (1), wherein the metal ion-containing compound is a water-soluble compound.

(3) The image receiving sheet for thermal transfer as described in (1), further comprising a release agent in addition to the metal ion-containing compound.

(4) The thermal transfer image-receiving sheet according to (1), wherein two or more image-receiving layers are formed by simultaneous aqueous multi-layer coating.

(5) A slide hopper is used for simultaneous multilayer coating.
(4) The image receiving sheet for thermal transfer according to (4), which is performed by using an extrusion coater or a curtain coater.

(6) The compound containing a metal ion has a boiling point of 120
An image-receiving sheet for thermal transfer having an image-receiving layer formed by an aqueous coating solution dissolved in an oil at a temperature of not less than ° C and dispersed in an aqueous binder.

(7) An aqueous coating solution containing a thermoplastic resin and a metal ion-containing compound dispersed in an aqueous system is applied and dried, and then subjected to ultraviolet irradiation, diffusion of a crosslinking agent, heat treatment, or replenishment of moisture. An image-receiving sheet for thermal transfer having an image-receiving layer obtained by crosslinking a thermoplastic resin.

The details of the image receiving sheet for thermal transfer (hereinafter also referred to as image receiving sheet), the ink sheet for thermal transfer recording (hereinafter also referred to as ink sheet), and the image forming method (thermal transfer recording) will be described in this order.

(Image Receiving Sheet for Thermal Transfer) The image receiving sheet of the present invention basically comprises a support and an image receiving layer formed thereon.

The support of the image receiving sheet is not particularly limited, and various materials, layer constitutions and sizes can be appropriately selected and used according to the purpose of use. For example, various papers such as paper, coated paper, and synthetic paper (polypropylene, polystyrene, or a composite material obtained by laminating them with paper), a vinyl chloride resin sheet, an ABS resin sheet, a polyethylene terephthalate (PET) base film, Polybutylene terephthalate base film, polyethylene naphthalate (PEN) base film, polyarylate base film, polycarbonate base film, polyetheretherketone base film, polysulfone base film, polyethersulfone base film, polyetherimide base film, polyimide base film Or a single layer, or various plastic films or sheets obtained by laminating them in two or more layers, films or sheets formed of various metals,
Examples include films or sheets formed of various ceramics, and composite materials appropriately combined and laminated from those described above.

The support is preferably of high transparency when transparency is required, for example, for applications such as transparent originals such as OHP and seals to be attached to glass and the like. In the case of a reflection image, in order to enhance the sharpness of the formed image,
It is preferable that a white pigment, for example, titanium white, magnesium carbonate, zinc oxide, barium sulfate, silica, talc, clay, calcium carbonate or the like is added to the support.

The thickness of the support is usually 20 to 1000 μm,
It is preferably from 20 to 800 μm, and is appropriately selected from such a range.

The image receiving layer is formed by applying an aqueous coating solution containing a binder for an image receiving layer, a metal ion-containing compound (also referred to as a metal source), and various additives used as required. No metal source needs to be added to the upper layer of the image receiving layer.

As the binder for the image receiving layer, a binder having dyeing properties for the heat diffusible dye and having good solubility or dispersibility in water since it is used for preparing an aqueous coating solution described later. preferable.

Examples of such a binder include polyvinyl chloride resin, copolymer resin of vinyl chloride and other monomers (isobutyl vinyl ether, vinyl propionate, etc.), polyester resin, poly (meth) acrylic acid, poly (meth) acrylate, and the like. ) Acrylates, polyvinylpyrrolidone,
Polyvinyl acetal resin, polyvinyl alcohol,
Polycarbonate, cellulose triacetate, polystyrene,
Copolymers of styrene with other monomers (acrylates, acrylonitrile, ethylene chloride, etc.), copolymers of ethylene with other monomers (vinyl acetate, acrylates, etc.), vinyl toluene acrylate resin,
Examples include polyurethane resins, polyamide resins, urea resins, epoxy resins, phenoxy resins, polycaprolactone resins, polyacrylonitrile resins, cellulose resins such as methylcellulose, gelatin, starch, casein, and modified products thereof.

Among the above-mentioned resins, preferred for the purpose of the present invention are polyvinyl chloride resins, copolymers of vinyl chloride with other monomers, polyvinyl acetal resins, copolymers of styrene with other monomers, Polyester resin,
Epoxy resin.

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

The above various resins may be newly synthesized and used, or commercially available products may be used.

In the formation of the image receiving layer, the various resins mentioned above utilize their reactive sites (if no reactive sites are present, they are applied to the resin), and are crosslinked or irradiated with radiation, heat, a catalyst or the like. It is preferably cured.

In this case, a radiation-active monomer such as epoxy or acrylic, or a cross-linking agent such as isocyanate can be used, and these may be added as they are to the coating solution. In the case where it reacts with water, it is preferable to use it after microencapsulation.

Examples of the metal ion constituting the metal source contained in the image receiving layer include divalent and polyvalent metals belonging to Groups I to VIII of the periodic table.
1, Co, Cr, Cu, Fe, Mg, Mn, Mo, N
i, Sn, Ti and Zn are preferred, and especially Ni, Cu,
Co, Cr and Zn are preferred.

The metal source containing these metal ions is preferably an inorganic or organic salt of the metal and a complex of the metal. Specific examples include Ni, Cu, Co,
Inorganic metal salts such as halides, hydroxides, cyanides, sulfides, sulfates, nitrates, perchlorates and thiocyanates of Cr and Zn, and organic acids such as acetic acid, oxalic acid, citric acid and higher fatty acids Metal salt, Ni ²⁺ , Cu ²⁺ , Co ²⁺ , Cr ²⁺
And a complex containing Zn ²⁺ and represented by the following general formula is preferably used.

[M (Q ₁ ) _k (Q ₂ ) _m (Q ₃ ) _n ] ^{p +} p (L ⁻ ) In the formula, M represents a metal ion, and Q ₁ , Q ₂ and Q ₃ each represent M
Represents a coordination compound capable of coordinating with a metal ion represented by the following formula. These coordination compounds may be selected from, for example, coordination compounds described in “Chelate Chemistry (5) (Nankodo)”. it can. Particularly preferably, a coordination compound having at least one amino group coordinated with a metal can be mentioned. More specifically, ethylenediamine and its derivatives, glycinamide and its derivatives, picolinamide and its derivatives are No.

L is a counter anion capable of forming a complex,
Examples thereof include inorganic compound anions such as Cr, SO ₄ , and ClO ₄ , and organic compound anions such as benzenesulfonic acid derivatives and alkylsulfonic acid derivatives. Particularly preferred are tetraphenylboron anions and derivatives thereof, and alkylbenzenesulfonic acid anions and derivatives thereof. It is.

K represents 1, 2 or 3, m represents 1, 2 or 0, and n represents 1 or 0, which represents whether the complex represented by the above general formula is tetradentate, Is determined by the number of ligands of Q ₁ , Q ₂ and Q ₃ . p represents 1, 2 or 3.

Examples of this type of metal source include those exemplified in US Pat. No. 4,987,049.

The addition amount of the metal source is preferably 0.5 to 20 g / m ² , more preferably 1 to 15 g / m ² , based on the image receiving layer.

If necessary, additives such as a release agent, a surfactant, an antioxidant, a UV absorber, a light stabilizer, a filler (inorganic fine particles, organic resin particles), and a pigment are added to the image receiving layer. You may. Further, a plasticizer, a heat-meltable substance or the like may be added as a sensitizer.

The release agent is for improving the releasability between the ink sheet and the image receiving sheet, and is preferably contained in the outermost layer in the present invention.

Examples of such release agents include silicone oils (including those referred to as silicone resins); solid waxes such as polyethylene wax, amide wax, and Teflon powder; fluorine-based and phosphate-based surfactants And the like, among which silicone oil is preferred.
This silicone oil is classified into a type that is simply added (simple addition type) and a type that is cured or reacted (curing reaction type).

In the case of the simple addition type, a modified silicone oil (polyester-modified silicone oil, urethane-modified silicone oil, acryl-modified silicone oil, alcohol-modified silicone oil, amide-modified silicone oil, Oil or the like).

The amount of addition of these simple addition type silicone oils cannot be determined uniformly because they vary variously depending on the type thereof. However, in general, the addition amount is usually 0.1% with respect to the binder for the image receiving layer. It is 1 to 50% by weight, preferably 0.5 to 20% by weight.

As the curing reaction type silicone oil,
Reaction curing types (such as those obtained by reaction-curing an amino-modified silicone oil and an epoxy-modified silicone oil), photo-curing types, and catalyst-curing types.

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

The release agent layer may be provided on a part of the surface of the image receiving layer by dissolving or dispersing the above release agent in an appropriate solvent and applying the resultant, followed by drying.

The surfactant is used for improving the coating property of the coating solution for forming an image receiving layer on a support, and includes a conventionally used anionic, cationic, nonionic or amphoteric surfactant. Either can be used.

The antioxidant is described in JP-A-59-1.
Nos. 82785 and 60-130735;
Examples of the antioxidant include compounds described in JP-A-27387 and known compounds that improve image durability in photographs and other image recording materials.

The UV absorbers and light stabilizers are described in JP-A-59-158287, JP-A-63-74686, JP-A-63-145089, JP-A-59-196292 and JP-A-59-196292.
2-229594, 63-122596, 61
Compounds described in JP-A-283595 and JP-A-1-204788, and compounds known to improve image durability in photographs and other image recording materials can be mentioned.

Examples of the filler include inorganic fine particles and organic resin particles. As inorganic fine particles,
Silica gel, calcium carbonate, titanium oxide, acid clay,
Activated clay, alumina and the like can be mentioned, and organic fine particles include resin particles such as fluorine resin particles, guanamine resin particles, acrylic resin particles, and silicon resin particles. These inorganic / organic resin particles vary depending on the specific gravity, but are preferably added in an amount of 0 to 30% by weight.

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

Examples of the plasticizer include phthalic esters, trimellitic esters, adipic esters, other saturated or unsaturated carboxylic esters,
Citric acid esters, epoxidized soybean oil, epoxidized linseed oil, epoxystearate epoxys, orthophosphates, phosphites, glycolesters and so-called polymeric plasticizers such as polyvinyl acetate and polyol And the like.

Examples of the heat-fusible substance include alcohols such as terpineol, menthol, 1,4-cyclohexanediol, and phenol; amides such as acetamide and benzamide; esters such as coumarin and benzyl cinnamate; diphenyl ether and crown ether Ethers such as camphor and p-methylacetophenone; aldehydes such as vanillin and dimethoxybenzaldehyde; hydrocarbons such as norbornene and stilbene; higher fatty acids such as margaric acid; higher alcohols such as eicosanol; cetyl palmitate. And higher molecular weight compounds such as higher fatty acid amides such as stearic acid amide, higher amines such as behenylamine, carnauba wax, beeswax, paraffin wax, ester wax, montan And rosin derivatives such as rosin maleic acid resin and rosin phenol resin; phenol resins, ketone resins, epoxy resins, diallyl phthalate resins, terpene resins, aliphatic hydrocarbon resins, and cyclopentadiene resins. , Polyolefin resin, polyethylene glycol,
Examples include high molecular compounds represented by polyolefin oxides such as polypropylene glycol.

In the present invention, the above-mentioned heat-meltable substance preferably has a melting point or softening point of 10 to 150 ° C.

It is generally preferred that the total amount of these additives be selected in the range of 0.1 to 30% by weight based on the binder for the image receiving layer.

The thickness of the image receiving layer is appropriately selected so that the total of the plurality of layers is usually in the range of 3 to 30 μm, preferably 5 to 20 μm. The plurality of layers may have the same composition or different compositions. The image receiving layer may have a single-layer structure. Further, 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 insulating properties, barrier properties, cushioning properties, and adhesive properties.

When the above-mentioned intermediate layer is provided, its thickness is
Usually, it is preferable to select the range of 2.0 to 40 μm.

The image-receiving sheet for thermal transfer of the present invention is prepared by dispersing or dissolving the components for forming the image-receiving layer in water or an aqueous solution to prepare an aqueous coating solution, and applying this aqueous coating solution to the surface of the support. It can be manufactured by a drying coating method.

When the aqueous coating solution is prepared, the water-based coating solution may be prepared according to the solubility or dispersibility of the binder for the image receiving layer in water.
It is desirable to dissolve or disperse the resin in water. In some cases, an alcohol-based solvent, acetone, dioxane, or the like that is mixed with water may be used in combination at a ratio of 20% by weight or less based on 100% by weight of water.

That is, in order to prepare this aqueous coating liquid, a water-soluble resin (water-soluble polyvinyl acetal resin, water-soluble polyester, polyvinyl alcohol, starch, casein, gelatin, polyacrylic) in which the binder is well dissolved in water is used. Acid, etc.), if it is dissolved in water or an aqueous solution, or if the binder is an emulsion resin formed by solution polymerization using water as a solvent (polyvinyl chloride resin, styrene-butadiene copolymer, etc.), The resin is appropriately suspended in water or an aqueous solution together with a surfactant, or the binder is dispersed in water by using a dispersant or the like. If it is a coalescent), using a dispersing agent and a known dispersing machine such as an attritor, a ball mill, and a sand grinder. Or it is to desirably dispersed in an aqueous solution.

These coating liquids can be used in combination as appropriate, and emulsion resins and dispersion resins can be used as commercially available suspensions (vinyl chloride latex, styrene-butadiene latex, ethylene- (A vinyl acetate latex, a water-dispersible polymer polyester, etc.) or a dispersion liquid.

The aqueous coating solution is applied onto the support by a known coating method, for example, an extrusion coating method, a wire bar coating method, a roll coating method, or the like. Drying after application may be forced drying or natural drying.

As described above, when the aqueous coating solution is used for forming the image receiving layer, the environmental suitability during the production of the image receiving sheet is remarkably improved as compared with the case where a conventional organic solvent is used. It should be further noted that the use of an aqueous coating liquid makes it difficult for the image formed on the image receiving layer to blur after printing and during storage, and also improves the storability of the image. Incidentally, the image receiving layer may be formed over the entire surface of the support,
Depending on the purpose of use, it may be formed on a part of the surface of the support.

(Ink Sheet for Thermal Transfer Recording) Next, an ink sheet used together with the image receiving sheet of the present invention will be described.

The ink sheet basically includes a support and an ink layer formed thereon.

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

The heat diffusible dye used in the present invention is a magenta dye, a yellow dye or a cyan dye capable of forming a chelate of at least bidentate, and is preferably a dye represented by the following formula [D].

[0065]

Embedded image

Wherein X ¹ has at least one ring of 5 to 7
Represents the group of atoms necessary to complete an aromatic carbocyclic or heteroaromatic ring composed of a number of atoms, and at least one of the adjacent positions of the carbon atom bonded to the azo bond is a nitrogen atom or a chelating group. Is a substituted carbon atom. X ² represents an aromatic heterocyclic ring or an aromatic carbocyclic ring in which at least one ring is composed of 5 to 7 atoms, and G represents a chelating group.

Specific examples of such dyes include, for example, JP-A-59-78893 and JP-A-59-109349,
Compounds described in JP-A-4-94974 and JP-A-4-97894 can be exemplified as suitable compounds.

The amount of the heat diffusing dye used is usually from 0.1 to ²⁰ g, preferably from 0.2 to 5 g per m ^{2 of} the support.
g.

The ink layer may be formed as a layer containing a monochromatic heat diffusible dye on the entire surface or a part of the surface of the support, or a yellow ink containing a binder and a yellow dye. The layer, the magenta ink layer containing the binder and the magenta dye, and the cyan ink layer containing the binder and the cyan dye are formed on the entire surface or a part of the surface of the support at a constant repetition along the plane direction. You may.

The thickness of the ink layer is usually 0.2 to 10 μm.
m, and preferably 0.3 to 3 μm.

Examples of the binder for the ink layer include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose acetate butyrate; polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, and polyester. , Polyvinyl acetate, polyacrylamide, polyvinyl acetoacetal, styrene resin, styrene copolymer resin, polyacrylic ester, polyacrylic acid, vinyl resin such as acrylic acid copolymer, rubber resin, ionomer resin, olefin resin Resins.

Among these resins, polyvinyl butyral, polyvinyl acetoacetal or cellulose resin having excellent acid resistance is preferable.

One of these various binders can be used alone, or two or more of them can be used in combination.

The weight ratio of the binder to the heat-diffusing dye is preferably from 1:10 to 10: 1, and particularly preferably from 2: 8 to 8: 2.

Further, various additives can be added to the ink layer as long as the object of the present invention is not impaired.

Examples of the additives include fillers such as metal fine powder, silica gel, metal oxide, carbon black and resin fine powder, release agents such as silicon resin and fluorine resin, and curing agents (isocyanates) capable of reacting with binder components. Radioactive compounds such as nates, acrylics and epoxies).

Further, as an additive, a heat-fusible substance for promoting transfer, for example, compounds described in JP-A-59-106997, such as waxes and higher fatty acid esters, can be mentioned.

As the support for the ink sheet, any material can be used as long as it has good dimensional stability and can withstand heat during recording with a thermal head. Thin paper such as condenser paper and glassine paper, PET, PEN, polyamide A heat-resistant plastic film such as polycarbonate, polysulfone, polyvinyl alcohol, cellophane, and polystyrene can be used.

The thickness of the support is preferably from 2 to 10 μm. The support is provided with an undercoat layer for the purpose of improving adhesiveness to a binder, and preventing transfer and dyeing of the dye to the support. May have.

Further, a backing layer may be provided on the back surface of the support (the side opposite to the ink layer) for the purpose of running stability, heat resistance, antistatic and the like. The thickness of the backing layer is usually 0.1 to 1 μm.

The shape of the support is not particularly limited.
For example, there are arbitrary shapes such as wide sheets and films, narrow tapes and cards.

The ink sheet is prepared by dispersing or dissolving the above-mentioned various components for forming an ink layer in a solvent to prepare a coating liquid for forming an ink layer, coating this on the surface of a support, and drying. Can be manufactured.

According to the present invention, convenience in use can be achieved by forming perforations on the ink sheet or providing detection marks for detecting the positions of areas having different hues.

The ink sheet is not limited to the structure including the support and the ink layer formed thereon, and another layer may be formed on the surface of the ink layer. For example, an overcoat layer may be provided for the purpose of preventing set-off (blocking) of the thermally diffusible dye.

(Thermal Transfer Recording = Image Formation) In order to form an image, the ink layer of the ink sheet and the image receiving layer of the image receiving sheet of the present invention are superimposed, and thermal energy is applied imagewise to the interface between the ink layer and the image receiving layer. give.

In this way, the thermal diffusible dye in the ink layer is vaporized or sublimated by an amount corresponding to the applied thermal energy, and is transferred to the image receiving layer and received. As a result, an image is formed on the image receiving layer. At this time, since the heat diffusible dye is a dye that can be chelated, it reacts with the metal source contained in the image receiving layer to form a chelate, thereby improving the fixability of the dye in the image receiving layer.

As the heat source for giving the thermal energy,
A thermal head is generally used, but other known heat sources such as a laser beam, an infrared flash, and a hot pen can be used.

When using a thermal head as a heat source,
By modulating the voltage or pulse width applied to the thermal head, the applied thermal energy can be changed continuously or in multiple steps.

When laser light is used as a heat source, the heat energy to be given can be changed by changing the amount of laser light or the irradiation area.

In this case, a laser light absorbing material (such as carbon black or an infrared absorbing material in the case of a semiconductor laser) may be present in the ink layer or in the vicinity of the ink layer in order to easily absorb the laser light.

When using a laser beam, it is desirable that the ink sheet and the image receiving sheet are sufficiently adhered to each other.

If a dot generator having a built-in acousto-optic element is used, heat energy corresponding to the size of a halftone dot can be applied.

When an infrared flash lamp is used as a heat source, the heating may be performed through a colored layer such as black as in the case of using laser light. Alternatively, heating may be performed through a pattern or a halftone pattern that continuously expresses the shading of an image such as black, or a negative layer corresponding to a negative of the above-described pattern with a colored layer such as black on one surface. And heating may be performed in combination.

The thermal energy may be applied from the ink sheet side, from the image receiving sheet side, or from both sides. If priority is given to the effective use of thermal energy, the thermal energy may be applied from the ink sheet side. It is desirable to do.

By the above-described thermal transfer recording, one color image can be recorded on the image receiving layer of the image receiving sheet. However, according to the following method, a color image of a color photographic tone composed of a combination of each color can also be obtained. .

For example, by sequentially replacing the yellow, magenta, cyan, and, if necessary, black ink sheets, and performing thermal transfer in accordance with each color, a color image of a color photographic tone composed of a combination of each color can be obtained.

In addition, the following method is also effective.

That is, instead of using the ink sheets of each color as described above, an ink sheet having an area previously formed by applying each color separately is used. Then, first, the yellow color separation image is thermally transferred using the yellow area,
Next, a method of thermally transferring the magenta color separation image using the magenta area, and thereafter sequentially repeating the thermal transfer of the yellow, magenta, cyan and, if necessary, black color separation images is adopted. With this method, it is possible to obtain a color photographic color image, but more advantageously, this method has the advantage that the replacement of the ink sheet as described above is not required.

After an image is formed by the above-described method, a heat treatment may be performed by the above-mentioned method for the purpose of improving image storability. For example, a heat treatment may be performed on the entire surface of the image forming surface by using a portion of the ink sheet where the ink layer is not provided with a thermal head, or a heat treatment such as a heat roll may be newly performed. When a near-infrared absorbing agent is contained, the image forming surface may be exposed using an infrared flash lamp.

In any case, the heating means is not limited. However, since the purpose is to further diffuse the dye into the image receiving layer, it is effective and preferable to heat from the support side of the image receiving layer.

[0101]

Next, the present invention will be described more specifically with reference to examples. In the following examples, “parts” means “parts by weight” unless otherwise specified.

Example 1 <Preparation of Ink Sheet> A PET film having a heat-resistant protective layer having a thickness of 6 μm as a support (Lumirror 6 manufactured by Toray Industries, Inc.)
On the back surface of the protective layer of CF531), yellow having the following composition,
The magenta and cyan ink layer coating liquids were applied by a gravure method (thickness after drying was 1 μm) to obtain an ink sheet in which yellow, magenta and cyan ink layers and blank portions where nothing was applied were formed in a plane-sequential manner. .

Yellow ink layer coating solution Post-chelating dye Y-1 20 parts below Polyvinyl acetal (KY-24 manufactured by Denki Kagaku Kogyo Co., Ltd.) 80 parts Magenta ink layer coating solution Post-chelating dye M-1 20 parts Polyvinyl acetal (Electric) 80 parts of cyan ink layer coating solution 20 parts of the following post-chelating dye C-1 polyvinyl acetal (KY-24, manufactured by Denki Kagaku Kogyo Co., Ltd.) 80 parts

[0104]

Embedded image

<Preparation of Image-Receiving Sheet>
An anchor layer coating solution having the following composition and an image receiving layer coating solution are applied in this order on a 75 μm synthetic paper (manufactured by Oji Yuka Co., Ltd .: YUPO), and an anchor layer having a thickness of 0.5 μm and a thickness of 4 μm are coated.
m was formed to obtain an image receiving sheet.

Anchor Layer Coating Solution Polyvinyl Butyral 90 parts (Sekisui Chemical Co., Ltd .: Eslec BL-1) Isocyanate 10 parts (Nippon Polyurethane Industry Co., Ltd .: Coronate HX) After coating and drying, aging was performed at 30 ° C. for 7 days to cure.

Image receiving layer coating solution Acrylic resin latex 32.5 parts (Nipol LX854, manufactured by Zeon Corporation) Metal source (MS-1) 20.0 parts Polyester modified silicone resin 2.5 parts (Shin-Etsu Silicone: X -24-8300) water 40.0 parts of ethanol 5.0 part ^{MS-1: Ni 2+ (NH} 2 COCH 2 NH 2) 3 · 2B (C
₆ H _{5) 4} ^- <Formation of Image> using A4 sublimation thermal transfer line printer, to form yellow, magenta, and cyan solid image,
Further, the image receiving layer on which the image was formed by the same head was heated through the blank portion of the ink sheet to form a yellow, magenta, and cyan image having a density of 1.0.

<Evaluation of Image Preservability> The above color image was irradiated to a xenon fade meter (70,000 lux) for 14 days, and the density of the image having a reflection density of 1.0 for each color after the irradiation was measured. The residual rate of the image was determined. The chelation rate was determined from the absorption spectrum of the image.

Example 2 The image receiving layer of the image receiving sheet of Example 1 was replaced with the image receiving layer 1 having the following composition.
An image receiving sheet was produced in the same manner as in Example 1 except that the coating solution and the image receiving layer 2 were applied by a slide hopper coater. However, the dried film thickness of the image receiving layer 1 was 3.3 μm and that of the image receiving layer 2 was 0.7 μm.

Image receiving layer 1 coating solution Vinyl chloride resin-based latex 27.5 parts (manufactured by Zeon Corporation: G576) Metal ion (NiCl ₂ ) 5 parts Polyester modified silicone resin 2.5 parts (see above: X-24-8300) Water 30 parts Ethanol 5 parts Image receiving layer 2 coating solution Polyethylene wax emulsion (Toho Chemical Industry Co., Ltd .: Hitec E-1000) 20 parts Urethane-modified ethylene acrylic acid polymer emulsion (Toho Chemical Industry Co., Ltd .: S-6254) 79 parts Hydroxy Ethylcellulose 1 part (Shin-Etsu Science Co., Ltd .: SM-15) A performance test was performed in the same manner as in Example 1 using the above image-receiving sheet.

Example 3 The same procedure as in Example 2 was carried out except that the coating solution for the image receiving layer 1 of the image receiving sheet of Example 2 was replaced with the coating solution for the image receiving layer 3 having the following composition, and the coating solution for the image receiving layer 2 was overcoated with a curtain coater. An image receiving sheet was produced. However, immediately after coating, the film was conveyed while being blown with cold air at 5 ° C., and then dried.

Image receiving layer 3 coating solution Gelatin 5 parts Vinyl chloride resin-based latex (mentioned above: G576) 25 parts Metal source (MS-2) 20 parts Dibutyl phthalate 5 parts Ethyl acetate 20 parts Saponin 1 part Cyanuric chloride (curing agent) 0.5 part Water 50 parts However, the metal source, dibutyl phthalate and ethyl acetate were mixed and charged and dispersed in an aqueous solution containing saponin and gelatin.

MS-2: Ni ²⁺ [CH ₃ COC (COO
CH ₃ ) = C (C ₇ H ₁₅ ) O ⁻ ] _{2 A} performance test was performed in the same manner as in Example 2 using the obtained image receiving sheet.

Comparative Example An image receiving sheet was prepared in the same manner as in Example 1 except that the image receiving layer of the image receiving sheet of Example 1 was replaced with an image receiving layer coating solution having the following composition.

Image receiving layer coating solution Polyvinyl acetoacetal resin 11 parts (manufactured by Sekisui Chemical Co., Ltd .: KW-1) Metal source (described above: MS-1) 8 parts Polyester modified silicone resin 80 parts (described above: X-24) 8300) A performance test was performed using the obtained image receiving sheet in the same manner as in Example 1.

Table 1 also shows the results of Examples 1 to 3 and Comparative Example.

[0117]

[Table 1]

It can be seen that all the examples using the image receiving sheet of the present invention show excellent image storability. In the comparative example, a part of the maximum density (D _max ) portion of yellow was fused to the ink layer, and there was a portion where the entire binder was transferred. An image was obtained.

[0119]

According to the present invention, an image receiving sheet for thermal transfer can be produced at a low cost and in a good working environment without using a harmful organic solvent. Was improved, and a color image having excellent storage stability was obtained.

Claims (7)

[Claims] 1. A metal ion having an image receiving layer comprising at least two layers formed by aqueous coating on a support, and forming a chelate by reacting with a heat diffusible dye in a lower layer of the image receiving layer. An image-receiving sheet for thermal transfer, comprising a compound. 2. The image receiving sheet for thermal transfer according to claim 1, wherein the metal ion-containing compound is a water-soluble compound. 3. The image receiving sheet for thermal transfer according to claim 1, further comprising a release agent in addition to the metal ion-containing compound. 4. The thermal transfer image receiving sheet according to claim 1, wherein two or more of the image receiving layers are formed by simultaneous aqueous multi-layer coating. 5. The thermal transfer image-receiving sheet according to claim 4, wherein the simultaneous multi-layer coating is performed by using a slide hopper, an extrusion coater or a curtain coater. 6. An image-receiving sheet for thermal transfer, comprising an image-receiving layer formed of an aqueous coating solution in which a metal ion-containing compound is dissolved in an oil having a boiling point of 120 ° C. or higher and dispersed in an aqueous binder. 7. An aqueous coating solution containing a thermoplastic resin dispersed in an aqueous system and a metal ion-containing compound, which is applied and dried, and then irradiated with ultraviolet light, diffusion of a crosslinking agent, heat treatment, or replenishment of moisture. An image receiving sheet for thermal transfer, comprising an image receiving layer obtained by crosslinking a plastic resin.