JP2955001B2 - Ink sheet for thermal transfer recording - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink sheet for thermal transfer recording, and more particularly to an ink sheet for thermal transfer recording having improved storage stability and dye transferability.

[Prior Art and Problems to be Solved by the Invention] Conventionally, as a method for obtaining a color hard copy, a color recording technique using ink jet, electrophotography, thermal transfer, or the like has been studied.

Among them, the thermal transfer method has advantages such as easy operation and maintenance, downsizing of the apparatus and cost reduction.

 The following two types of thermal transfer systems are available.

That is, a method in which a transfer sheet having a fusible ink layer on a support is image-wise heated by a laser or a thermal head to melt-transfer the fusible ink layer onto an image receiving sheet for thermal transfer recording; Using a thermal transfer recording ink sheet having an ink layer containing a thermal diffusible dye (sublimable dye), and diffusing and transferring the thermal diffusible dye to an image receiving sheet for thermal transfer recording. It is.

Of these, the thermal diffusion transfer method can control the gradation of the image by changing the amount of dye transfer according to the change in the thermal energy of the thermal head. In recent years, attention has been paid to a method of obtaining a color image having a continuous change in color shading by performing the method.

However, the first problem with this thermal diffusion transfer method is that the storage stability of the thermal transfer recording ink sheet used is not good. When stored, the thermal diffusible dye is released from the binder over time and accumulates on the surface of the ink layer, and moves to the back surface of the sheet that is in contact with the dye. May be contaminated (dirt).

The second problem is that the transferability of the dye from the thermal transfer recording ink sheet to the thermal transfer recording image receiving sheet is not sufficient.

That is, in the thermal transfer recording ink sheet in which the heat-diffusible dye has been released from the binder, the dye concentration is reduced, so that it is difficult to form a high-density clear image on the thermal transfer recording image-receiving sheet side. It is.

The present invention has been made to solve the above problems.

That is, an object of the present invention is to provide an ink sheet for thermal transfer recording which is excellent in the storability of the sheet itself and the dye transferability.

[Means for Solving the Problems] According to the present invention for achieving the above object, an ink layer containing a polyvinyl acetal-based resin and / or a cellulose-based resin, a polyparabanic acid resin, and a heat-diffusible dye is provided on a support. Which is a thermal transfer recording ink sheet.

 Hereinafter, the present invention will be described in detail.

(1.) Ink Sheet for Thermal Transfer Recording The ink sheet for thermal transfer recording of the present invention basically comprises an ink layer laminated on a support.

—Ink Layer— The ink layer contains a heat diffusing dye and a binder as essential components.

1. Thermally diffusible dye The thermal diffusible dye used in the present invention is not particularly limited as long as it is thermally diffusible or sublimable.

Thermal diffusible dyes include cyan dye, magenta dye,
Yellow dyes can be mentioned.

Examples of the cyan dye include JP-A-59-78896 and JP-A-59-78896.
-227948, 60-24966, 60-53563, 60-13
No. 0735, No. 60-131292, No. 60-239289, No. 61-1939
No. 6, No. 61-22993, No. 61-31292, No. 61-31467,
No. 61-35994, No. 61-49893, No. 61-148269, No. 62
-191191, 63-91288, 63-91287, 63-29
Examples include naphthoquinone-based dyes, anthraquinone-based dyes, and azomethine-based dyes described in each publication such as No. 0793.

Examples of the magenta dye include JP-A-59-78896, JP-A-60-30392, JP-A-60-30394, and JP-A-60-2535.
No. 95, JP-A-61-262190, JP-A-63-5992, JP-A
Examples include anthraquinone dyes, azo dyes, and azomethine dyes described in JP-A-63-205288, JP-A-64-159, JP-A-64-63194, and the like.

As yellow dyes, JP-A-59-78896, JP-A-6-78896
0-27594, JP-A-60-31560, JP-A-60-53565,
Examples include methylene dyes, azo dyes, quinophthalone dyes and anthrisothiazole dyes described in JP-A-61-12394 and JP-A-63-122594.

Further, as the thermal diffusible dye, an azomethine dye obtained by coupling a compound having a closed or closed type active methylene group with an oxidized form of a p-phenylenediamine derivative or an oxidized form of a p-aminophenol derivative; And phenol or naphthol derivatives or p
An indoaniline dye obtained by a coupling reaction with an oxidized form of a phenylenediamine derivative or an oxidized form of a p-aminophenol derivative can also be suitably used.

The thermal diffusible dye may be any of a yellow dye, a magenta dye, and a cyan dye as long as the image to be formed is a single color.

Further, depending on the color tone of the image to be formed, two or more of the three types of heat diffusible dyes or other colors may be included.

The amount of the heat-diffusible dye used in the present invention depends on the support.
It is usually 0.1 to 20 g, preferably 0.2 to 5 g per 1 m2.

2. Binder In the present invention, a polyvinyl acetal-based resin and / or a cellulose-based resin and a polyparabanic acid resin are used as essential components as a binder used in the ink layer (hereinafter, referred to as “binder”).
These may be referred to as essential resins).

Only when these essential resins are used as a binder, the thermal transfer recording ink sheet has improved storage stability and, at the same time, improved dye transferability.

Examples of the polyvinyl acetal-based resin include various compounds depending on the type of aldehyde to be acetalized, the degree of acetalization, and the content of acetyl groups, and typical examples thereof include polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral. Among them, polyvinyl acetoacetal and polyvinyl butyral are preferred in the present invention.

Among the acetal resins, preferred for the purpose of the present invention are those having a polymerization degree of 300 to 3000 and an acetalization degree of 60 mol%.
Above, acetyl group is 10 mol% or less, glass transition point (Tg)
Is an acetal resin having a temperature of 50 ° C. or higher.

The commercial names of the acetal resins satisfying such conditions are listed as S-LEC KS-1, KS-5, KS-8, BL-
1, BL-2, BL-3, BL-S, BM-1, BM-2, BM-
5, BM-S, BH-3, BX-1 [all manufactured by Sekisui Chemical Co., Ltd.], Denka Butyral ^# 2000-L, ^# 3000-
1, ^# 3000-2, ^# 3000-4, ^# 3000-K, ^# 4000-
1, ^# 4000-2, ^# 5000-A, and ^# 6000-C (manufactured by Denki Kagaku Kogyo KK).

The acetal-based resin can be used alone or in combination of two or more.

Examples of the cellulose resin include methyl cellulose, ethyl cellulose, nitrocellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cellulose propionate, cellulose acetate, cellulose acetate butyrate, cellulose acetate hydrogen phthalate, and the like. Among them, ethyl cellulose, ethyl hydroxyethyl cellulose and nitrocellulose are preferred in the present invention.

Cellulosic resins suitable for the present invention include commercially available ethyl cellulose, ethyl hydroxyethyl cellulose (manufactured by Hercules), Cellnova BT-SL, BTH-1 / 16, and BTH.
-1/4, BTH-1 / 2, BTH-1, BTK-SL, BTK-1 / 8, and the like (manufactured by Asahi Kasei Corporation).

The above various cellulose resins can be used alone or in combination of two or more.

Next, as the polyparabanic acid resin, a resin having a repeating unit represented by the following general formula [I] can be used.

However, as a typical R, And the like. Further, n in the general formula represents the number of repeating units.

Polyparabanic acid resins that can be suitably used in the present invention are commercially available Solulac XT-1 XT-2, XT-
3. Available as XT-4 (manufactured by Tonen Petrochemical Co., Ltd.) or the like.

The weight ratio of the used amount of the polyvinyl acetal-based resin and / or the cellulose-based resin to the used amount of the polyparabanic acid resin can be arbitrary as long as these three or two components coexist. In order to make the composition more excellent, it is usually 90:10 to 20:80, preferably 90:10 to 40:60.

In the present invention, a conventionally known resin can be used together with the essential resin as a binder.

In this case, the amount of the essential resin is usually in the range of 0 to 100% by weight based on the total amount of the essential resin and the known resin.

Examples of the known resin include a polyester resin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, a poly (meth) acrylic resin, polyacrylamide, a styrene resin, a styrene copolymer, a rubber resin,
Examples include an ionomer resin, an olefin resin, and a vinyl chloride resin.

In the present invention, the weight ratio of the binder to the heat diffusible dye in the ink layer is preferably from 1:10 to 10: 1.

3. Additive In the present invention, various additives can be added to the ink layer.

The additives include silicone resin, silicone oil (reaction curing type is also possible), silicone-modified resin, fluororesin, surfactant, release compounds such as waxes,
Fillers such as metal fine powder, metal fine powder, silica gel, metal oxide, carbon black, resin fine powder and the like, and curing agents capable of reacting with binder components such as isocyanates, acryls and epoxies). be able to.

Further, a heat-fusible substance for promoting transfer, such as wax or higher aliphatic ester, is disclosed in JP-A-59-1069.
No. 97 can be mentioned.

The amount of the additive cannot be determined unconditionally depending on the type of the additive and the purpose of the addition, but the total amount of the additive is usually in the range of 20% by weight or less based on the binder.

4. Formation of Ink Layer The ink layer is prepared by dispersing or dissolving the binder, the heat-diffusible dye, and optional components added as necessary in a solvent to prepare a coating liquid for forming an ink layer. It can be formed by applying a working liquid on a support and drying it.

The binder may be used not only by dissolving one kind or two or more kinds in a solvent, but also by dispersing it in a latex form.

Examples of the solvent include water, alcohols (eg, ethanol, propanol), cellosolves (eg, methyl cellosolve), aromatics (eg, toluene, xylene, chlorobenzene, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), and esters. (Eg, ethyl acetate, butyl acetate), ethers (eg, tetrahydrofuran, dioxane, etc.), and chlorinated solvents (eg, chloroform, trichloroethylene, etc.).

The above-mentioned coating can be performed by a known gravure roll, such as face-to-face coating, extrusion coating, wire bar coating, and roll coating.

The thickness of the ink layer is preferably from 0.2 to 10 μm, more preferably from 0.3 to 3 μm.

Further, the ink layer is a support in which a yellow ink layer containing a binder and a yellow pigment, a magenta ink layer containing a binder and a magenta pigment, and a cyan ink layer containing a binder and a cyan pigment are repeatedly repeated along a plane direction at a constant rate. Preferably, the structure is formed above.

Further, in addition to the three ink layers arranged along the surface direction, a black ink layer containing a black image forming substance may be interposed between any two horizontally adjacent layers.

In particular, for the black ink layer, a diffusion transfer type ink may be used, but a clear character can be obtained even with a melt transfer type ink.

—Support— The ink layer is preferably provided on a support.

The support used in the present invention has good dimensional stability and can withstand heat during recording with a thermal head.
Anything can be used, such as condenser paper, tissue paper such as glassine paper, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyamide,
A heat-resistant plastic film such as polycarbonate, polysulfone, polystyrene, or polyimide can be used.

 The thickness of the support is preferably 2 to 10 μm.

-Other layers- An undercoat layer can be provided between the ink layer and the support in order to enhance the adhesiveness and the like. Further, a fusion preventing layer can be provided on the ink layer.

The thickness is usually 0.01-5 μm, preferably 0.05-1 μm
m.

If the thickness is less than 0.01 μm, the effect of preventing fusion is not sufficiently exhibited, and if it exceeds 5 μm, it becomes difficult to obtain a high-density image by high-speed printing, which is not preferable.

The anti-fusion layer is usually a solid wax such as polyethylene wax, amide wax, Teflon powder,
It can be formed of a phosphate ester-based surfactant, silicone oil, silicone resin, or the like.

A sticking prevention layer may be provided on the back surface of the support (on the side opposite to the ink layer) for the purpose of preventing the head from sticking, sticking, and wrinkling to the support.

The thickness of the anti-sticking layer is preferably in the range of 0.1 to 1 μm.

Further, by forming a perforation on the thermal transfer recording ink sheet, or by providing a detection mark for detecting the position of an area having a different hue,
It is also possible to improve the convenience of use.

(2.) Image-receiving sheet for thermal transfer recording The image-receiving sheet for thermal transfer recording can be generally composed of a substrate and an image receiving layer formed thereon.

In some cases, the image-receiving sheet for thermal transfer recording can be formed with a self-supporting image-receiving layer.

In the heat-sensitive transfer recording image-receiving sheet including the self-supporting image-receiving layer, since a base material cannot be used, the number of parts can be reduced.

-Image receiving layer- This image receiving layer can be formed by using a binder for an image receiving layer and various additives.

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

1. Binder for image receiving layer As binder for image receiving layer, for example, polyvinyl chloride resin, vinyl chloride copolymer (for example, vinyl chloride-alkyl vinyl ether copolymer) polyester resin,
Acrylic ester, polyvinylpyrrolidone, polycarbonate, cellulose triacetate, styrene acrylate resin, vinyl toluene acrylate resin, polyurethane resin, polyamide resin, urea resin, polycaprolactone resin, styrene-maleic anhydride resin, polyacrylonitrile resin, etc. It is also possible to use one kind or a combination of two or more kinds.

Among them, polyvinyl chloride, vinyl chloride resin, polyester resin and the like are preferable.

The above various resins may be newly synthesized and used,
Commercial products can also be used.

In any case, from the viewpoint of physical properties, the binder for the image receiving layer particularly has a glass transition point (Tg) of -20 to 150 ° C.
Resins in the range of 30 to 120 ° C. are preferable, and from the viewpoint of molecular weight, Mw is 2,000 to 10
Resins in the range of 0,000 are preferred.

The resin uses its reactive active point (if there is no reactive active point, it is applied to the resin). Radiation, heat, moisture,
It may be crosslinked or cured by a catalyst or the like.

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

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 image receiving layer. Further, a plasticizer, a heat solvent and the like may be added as a sensitizer.

The release agent can improve the releasability of the thermal transfer recording ink sheet from the thermal transfer recording image receiving sheet.

Examples of such release agents include silicone oils (including those called silicone resins); solid waxes such as polyethylene wax, amide wax, and Teflon powder; and fluorine-based and phosphate-based surfactants. Among them, silicone oil is preferable.

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, it is preferable to use a modified silicone oil in order to improve the compatibility with the binder.

Examples of the modified silicone oil include polyester-modified silicone resin (or silicon-modified polyester resin), acryl-modified silicone resin (or silicon-modified acrylic resin), urethane-modified silicone resin (or silicon-modified urethane resin), and cellulose-modified silicone resin ( Alternatively, a silicon-modified cellulose resin), an alkyd-modified silicone resin (or a silicon-modified alkyd resin), an epoxy-modified silicone resin (or a silicon-modified epoxy resin), and the like can be given.

That is, a polyester-modified silicone resin containing a polysiloxane resin in the main chain and copolymerizing polyester in a block shape, a silicon-modified polyester resin having a dimethylpolysiloxane portion as a side chain bonded to the polyester main chain, and dimethylpolysiloxane. Block copolymers, alternating copolymers, graft copolymers, random copolymers, and the like of siloxane and polyester can also be used as the modified silicone oil or resin.

In particular, in the present invention, it is preferable to add a polyester-modified silicone resin.

Typical polyester-modified silicone resins include, for example, block copolymers of dimethylpolysiloxane with polyesters, which are copolymers of diols and dibasic acids or ring-opening polymers of caprolactone (both terminals or fragments of dimethylpolysiloxane). Including copolymers whose ends are blocked with the above polyester portion, or conversely, where the above polyester is blocked with dimethylpolysiloxane.) Or (dimethyl) polysiloxane bonded to the side chain with the above polyester as the main chain Examples of the copolymer include:

The amount of these simple addition type silicone oils is
Although it cannot be determined uniformly because it may vary variously depending on the type, generally speaking, it is usually 0.5 to 50% by weight, preferably 1 to 20% by weight, based on the binder for the image receiving layer. % By weight.

Examples of the curing reaction type silicone oil include reaction curing type, light curing type, and catalyst curing type.

As the reaction-curable silicone oil, there is one obtained by reacting and curing an amino-modified silicone oil and an epoxy-modified silicone oil.

KS-705F-PS, KS-705F-PS-1, KS-770-P as catalyst-curable or photocurable silicone oils.
L-3 [All are catalyst-curable silicone oils: manufactured by Shin-Etsu Chemical Co., Ltd.], KS-720, KS-774-PL-3 [All are photo-curable silicone oils: manufactured by Shin-Etsu Chemical Co., Ltd.]
And the like.

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-mentioned release agent in a suitable solvent and applying the resultant, followed by drying.

Next, examples of the antioxidant include JP-A-59-182785 and JP-A-59-182785.
60-130735, antioxidants described in JP-A-1-127387 and the like,
And known compounds for improving image durability in photographic and other image recording materials.

As the UV absorber and light stabilizer, JP-A-59-15
8287, 63-74686, 63-145089, 59-196292, 6
2-229594, 63-122596, 61-283595, JP-A 1-2
Examples of the compounds include compounds described in JP-A-04788 and compounds known to improve image durability in photographs and other image recording materials.

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, and alumina.
Resin particles such as guanamine resin particles, acrylic resin particles, and silicon resin particles can be used. This inorganic
The organic resin particles vary depending on the specific gravity, but are preferably added in an amount of 0.1 to 70% 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 phthalate esters (eg, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, didecyl phthalate, etc.) and trimellitate esters (eg, octyl trimellitate, isononyl trimellitate, Pyromellitic acid esters such as melitic acid isodesol ester), pyromellitic acid octyl ester and the like, adipic acid esters (dioctyl adipate, methyl lauryl adipate,
Di-2-ethylhexyl adipate, ethyl lauryl adipate), oleates, succinates, maleates, sebacates, citrates, epoxidized soybean oil, epoxidized linseed oil, Epoxy epoximate stearate, and further, orthophosphates such as triphenyl phosphate and tricresyl phosphate,
Examples include phosphites such as triphenyl phosphite, tris tridecyl phosphite, and dibutyl hydrogen phosphite, and glycol esters such as ethyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate.

In the present invention, the total amount of the additives is usually in the range of 0.1 to 50% by weight based on the binder for the ordinary image layer.

3. Formation of image receiving layer The image receiving layer is prepared, for example, by dispersing or dissolving the components for forming the image receiving layer in a solvent to prepare a coating solution for the image receiving layer, and applying the coating solution for the image receiving layer to the surface of the substrate. Then, it can be formed by a coating method of drying and a laminating method of melt-extruding a mixture having a component for forming the image receiving layer and laminating the mixture on the surface of a substrate.

Examples of the solvent used in the coating method include tetrahydrofuran, methyl ethyl ketone, toluene, xylene, chloroform, dioxane, acetone, cyclohexane, and normal butyl acetate. When the above-described laminating method is employed, when the base material is a synthetic resin as described later, a co-extrusion method may be employed. The image receiving layer may be formed over the entire surface of the substrate, or may be formed on a part of the surface.

The thickness of the image receiving layer is generally 3 to 50 μm, preferably 5 to 50 μm.
It is about 15 μm.

On the other hand, when the image receiving layer itself forms a thermal transfer recording image receiving sheet because the image receiving layer is self-supporting, the thickness of the image receiving layer is usually 60 to 200 μm, preferably 90 to 150 μm.
It is about.

-Substrate-Examples of the substrate include paper, coated paper, synthetic paper (polypropylene, polystyrene or a composite material obtained by bonding them with paper or a plastic film),
Examples include a white polyethylene terephthalate base film, a transparent polyethylene terephthalate base film, a transparent polyethylene naphthalate base film, and a polyolefin-coated paper.

The thickness of the substrate is usually 20 to 300 μm, preferably 30 to 300
μm.

-Other layers- An overcoat layer may be laminated on the surface of the heat-sensitive transfer recording image-receiving sheet for the purpose of preventing fusion and improving image storability. This layer can be formed by gravure coating, wire bar coating, roll coating, or other known coating methods or laminating methods. The thickness of this layer is usually from 0.05 to 5 μm.

A cushion layer may be provided between the base material and the image receiving layer of the image transfer sheet for thermal transfer recording in order to reduce noise and transfer and record an image corresponding to image information with good reproducibility.

Examples of the material constituting the cushion layer include urethane resin, acrylic resin, ethylene-based resin, butadiene rubber, and epoxy resin.

 The thickness of the cushion layer is preferably 5 to 25 μm.

(3.) Formation of Image In order to form an image, the ink layer surface of the thermal transfer recording ink sheet of the present invention and the image receiving layer surface of the thermal transfer recording image receiving sheet are overlapped so as to be in contact with each other. Apply thermal energy to the interface imagewise.

Then, the thermal diffusible dye in the thermal transfer recording ink sheet vaporizes or sublimates by an amount corresponding to the applied thermal energy, moves to the thermal transfer recording image receiving sheet side, and is fixed to the image receiving layer and there. Form an image.

A thermal head is generally used as a heat source for applying the heat energy. In addition, a known heat source such as a laser beam, an infrared flash, and a hot pen can be used.

The thermal energy may be applied from the thermal transfer recording image receiving sheet, from the thermal transfer recording ink sheet side, or from both.

However, from the viewpoint of effective use of heat energy,
It is preferred that the heat transfer recording be performed from the ink sheet side.

It is also used for controlling the thermal energy to express the shades of the image, or for promoting the diffusion of the dye to the image-receiving sheet for thermal transfer recording to more reliably express the continuous tone of the image. It is more preferable to apply thermal energy from the side of the thermal transfer recording image receiving sheet.

Further, from the viewpoint that the advantages of the above two methods can be enjoyed at the same time, it is preferable to carry out from the side of the ink sheet for thermal transfer recording and the side of the image receiving sheet for thermal transfer recording.

When a thermal head is used as a heat source for applying thermal energy, the applied thermal energy can be changed continuously or in multiple steps by modulating the voltage or pulse width applied to the thermal head.

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

By using a dot generator with a built-in acousto-optic element, it is possible to apply heat energy according to the size of a halftone dot.

When a laser beam is used as a heat source, it is desirable that the thermal transfer recording ink sheet and the thermal transfer recording image receiving sheet be sufficiently adhered to each other, and the surface irradiated with the laser beam is to improve the absorption of the laser beam. For example, it may be colored black.

When an infrared flash lamp is used as a heat source for applying heat energy, irradiation of the lamp is preferably performed through a colored layer such as black as in the case of using laser light.

Irradiation of this lamp can be performed through a pattern or a halftone pattern that continuously expresses the shading of an image such as black, or a colored layer such as black and a negative corresponding to the negative of the pattern. It can also be performed in combination with a pattern.

When the thermal energy is applied in this manner, a dye in an amount corresponding to the energy amount is thermally transferred from the thermal transfer recording ink sheet to the image receiving layer of the thermal transfer recording image receiving sheet, and a one-color image is recorded thereon. However, when the ink sheet for thermal transfer recording is replaced, a color image of a color photograph can be obtained.

For example, if the thermal transfer recording ink sheets of yellow, magenta, cyan and, if necessary, black are exchanged sequentially, and thermal transfer is performed in accordance with each color, a color photographic color image composed of a combination of each color can be obtained.

Instead of using the thermal transfer recording ink sheet of each color, the following method can be used.

That is, a thermal transfer recording ink sheet having areas formed separately in each color in advance is prepared, first, a yellow color separation image is thermally transferred using a yellow area, and then a magenta color separation image is formed using a magenta area. The color image is thermally transferred, and thereafter, this operation is sequentially repeated to thermally transfer the yellow, magenta, cyan, and, if necessary, black and color-separated images.

This method has an advantage that it is not necessary to replace the thermal transfer recording ink sheet.

[Examples] Next, the present invention will be described more specifically based on examples.

 In the following, “parts” means “parts by weight”.

Example 1 The following components were mixed and dispersed to prepare a coating solution for forming an image receiving layer.

Coating solution for forming image receiving layer; vinyl chloride-vinyl isobutyl ether copolymer 95 parts [BASF Co., Ltd., trade name: Laroflex MP-25] Polyester Modified silicone oil: 5 parts [Shin-Etsu Silicone Co., Ltd., trade name: X-24-8300] Methyl ethyl ketone: 500 parts Cyclohexanone: 50 parts Next The above-mentioned coating solution for forming an image receiving layer was coated on a synthetic paper having a thickness of about 150 μm (trade name: Yupo FPG; manufactured by Oji Yuka Synthetic Paper) using a wire bar, and dried at a temperature of 100 ° C. for 15 minutes. ,
An image receiving sheet for thermal transfer recording was obtained in which an image receiving layer having a thickness of about 6 μm was formed on synthetic paper.

On the other hand, a coating liquid for forming an ink layer having the following composition was applied to the surface of a polyethylene terephthalate sheet having a thickness of 6 μm having a silicone cured resin film having a thickness of about 1 μm provided on the back surface as a back coat layer, and dried to a thickness of about 1 μm. Was formed.

Coating liquid for forming ink layer; polyvinyl butyral resin 4 parts [degree of polymerization: 300, Tg: 59.2 ° C, manufactured by Sekisui Chemical Co., Ltd., trade name: Eslec BL-1] Polyparabanic acid resin ····· 1 part [manufactured by Tonen Petrochemical Co., Ltd., trade name: Solrack XT-1] Cyan sublimation disperse dye ····· 5 parts [manufactured by Nippon Kayaku , Kayaset Blue 714] Dioxane 120 parts Cyclohexanone 20 parts Next, the ink sheet for thermal transfer recording thus obtained is obtained. Is stored in an environment of a temperature of 60 ° C. and a relative humidity of 70% for 72 hours. Then, the heat-sensitive transfer recording ink sheet and the heat-sensitive transfer recording image-receiving sheet are Are placed so that they face each other, and the surface of the thermal transfer recording ink sheet is To perform image recording by heating with heads or others.

The recording density of the thermal head is 8 dots / mm, and the recording output is 0.35 W / dot.

After the image recording, the background contamination on the unprinted portion of the image receiving layer surface of the image receiving sheet for thermal transfer recording and the transfer density on the image receiving layer surface were evaluated according to the following criteria.

 The results are shown in Table 1.

Background stain: ○: There was no staining by the dye in the unprinted area on the surface of the image receiving layer.

 X: The unprinted portion was contaminated with dye.

Transfer density: The transfer density (reflection OD value) at a constant energy (0.35 W / dot) was measured.

(Example 2) The same operation as in Example 1 was performed except that the following coating liquid for forming an ink layer was used.

Ink layer forming coating liquid; Ethyl cellulose 4 parts [manufactured by Hercules, trade name: EC N-14] Polyparabanic acid resin 1 part [Tonen Petrochemical Co., Ltd., trade name: Sollac XT-1] Cyan sublimable disperse dye ..... 5 parts [Nippon Kayaku Co., Ltd., trade name; Kayaset Blue 714] Dioxane ... 120 parts Cyclohexanone 20 parts The results are shown in Table 1.

Example 3 Example 3 was carried out in the same manner as in Example 1 except that the following coating liquid for forming an ink layer was used.

Coating liquid for forming ink layer; polyvinyl butyral resin ... 2 parts [degree of polymerization: 1700, Tg: 85.5 ° C, manufactured by Sekisui Chemical Co., Ltd., trade name: Esrec BX-1] Ethyl cellulose ... ······ 2 parts [manufactured by Hercules Corporation, trade name: EC N14] Polyparabanic acid resin ····· 1 part [manufactured by Tonen Petrochemical Co., Ltd., trade name: Solrack XT-4 ] Cyan sublimable disperse dye 5 parts [manufactured by Nippon Kayaku Co., Ltd., trade name; Kayaset Blue 714] dioxane 120 parts cyclohexanone ... 20 parts The results are shown in Table 1.

(Comparative Example 1) The same operation as in Example 1 was performed except that the following coating liquid for forming an ink layer was used in the above example.

Ink layer forming coating liquid; Epoxy resin 4 parts [Yukaka Epoxy Co., Ltd., trade name: Epicoat 1255-
HX-30] Polyparabanic acid resin ······ 1 part [Product name: Solrack XT-1 manufactured by Tonen Petrochemical Co., Ltd.] Cyan sublimable disperse dye ······ 5 parts [Nippon Kayaku Co., Ltd., trade name; Kayaset Blue 714] Dioxane: 120 parts Cyclohexanone: 20 parts Results are shown in Table 1. Shown in

(Comparative Example 2) The same operation as in Example 1 was performed except that the following coating solution for forming an ink layer was used in Example.

Coating liquid for forming ink layer; polyvinyl butyral resin 4 parts [degree of polymerization: 300, Tg: 59.2 ° C, manufactured by Sekisui Chemical Co., Ltd., trade name: Eslec BL-1] Cyan sublimation dispersion Dye: 5 parts [Nippon Kayaku Co., Ltd., trade name: Kayaset Blue 714] Dioxane: 120 parts Cyclohexanone ... 20 parts The results are shown in Table 1.

[Effects of the Invention] The thermal transfer recording ink sheet of the present invention has improved storage stability, prevents the occurrence of background stains, and has good dye transferability, so that a clear and high-density image can be obtained. it can.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-11087 (JP, A) JP-A-63-151484 (JP, A) JP-A-3-189194 (JP, A) JP-A-3-301 292195 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] An ink sheet for thermal transfer recording, comprising an ink layer containing a polyvinyl acetal resin and / or a cellulose resin, a polyparabanic acid resin and a heat diffusible dye on a support.