JP3075482B2 - Ink sheet for thermal transfer recording - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an ink sheet for thermal transfer recording, and more particularly, to an ink sheet for thermal transfer recording, which enhances the preservability, causes soiling of the image receiving sheet for thermal transfer recording, and fuses with the image receiving sheet. The present invention relates to a thermal transfer recording ink sheet that can prevent the occurrence of image formation and suppress a decrease in image density.

[Prior Art and Problems to be Solved by the Invention] As a method for obtaining a color hard copy, a color recording technique using ink jet, electrophotography, thermal transfer, or the like is being 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 (imagewise) heated by a laser or a thermal head, and the fusible ink layer is melt-transferred onto an image receiving sheet for thermal transfer recording. Diffusion transfer using an ink sheet for thermal transfer recording having an ink layer containing a thermal diffusible dye (sublimable dye) on a support, and diffusing the thermal diffusible dye to an image receiving sheet for thermal transfer recording. And two types.

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 with the passage of time and accumulates on the ink layer surface, and moves to the back surface of the sheet in contact with the ink. May be contaminated with pigment (ground stain).

The second problem is that the image density (transfer density) of the ink sheet for thermal transfer recording, in which the thermal diffusible dye has been released from the binder, is reduced because the dye concentration is reduced.

The third problem is that, during thermal transfer, the entire ink layer from the thermal transfer recording ink sheet is fused to the thermal transfer recording image receiving sheet side.

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

That is, an object of the present invention is to provide a thermal transfer method capable of improving the storability, preventing fusion with an image receiving sheet for thermal transfer recording and preventing the image receiving sheet from being stained, and suppressing a decrease in image density. An object of the present invention is to provide a recording ink sheet.

Means for Solving the Problems The present invention for achieving the above object contains a heat diffusible dye, an acetal resin and nitrocellulose, and the weight ratio of the acetal resin and nitrocellulose contained. (Acetal resin / nitrocellulose) 50 / 50-85 /
15. An ink sheet for thermal transfer recording, wherein the ink layer of No. 15 is laminated on a support.

 Hereinafter, the present invention will be described in detail.

(I) Thermal Transfer Recording Ink Sheet The thermal transfer recording ink sheet of the present invention basically has a structure in which an ink layer 2 is laminated on a support 1 as illustrated in FIG.

—Ink Layer— The ink layer in the present invention basically contains a heat diffusible dye, an acetal resin, and nitrocellulose. The ink layer is not limited to a single layer, but may be composed of a plurality of layers.

Heat-diffusing dye The heat-diffusing dye used in the present invention is not particularly limited as long as it is heat-diffusing 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 thereof include methine dyes, azo dyes, quinophthalone dyes and anthrisothiazole dyes described in JP-A Nos. 61-12394 and 63-122594.

Further, as the heat diffusible dye, an azomethine dye obtained by coupling a compound having an open-chain 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 m ² .

Binder In the present invention, it is important to use an acetal resin and nitrocellulose as a binder used for the ink layer.

First, as the acetal-based resin, there are various compounds depending on the type of aldehyde to be acetalized, the degree of acetalization, the content of hydroxyl groups, acetyl groups, and the like. Representative examples include polyvinyl acetoacetal and polyvinyl butyral.

Among the acetal resins, preferred for the purpose of the present invention are those having a polymerization degree of 300 to 2400 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 include 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.]. These resins are not limited to one kind alone, and two or more kinds can be used in combination.

Further, nitrocellulose is preferably used for the purpose of the present invention when it has a nitrogen content of 10.7-12.2%, a degree of polymerization of 35-110, and a viscosity of 1.0-1.0, respectively, based on the test method of JIS K-6703.
6.2 seconds (measured at 25.0% solids), 3-8 seconds (solids 20.
0%), 1.5-500 seconds (measured at 12.2% solids), 1.1
It is a nitrocellulose having a value of 100 to 140 cps (measured by dissolving 1.5 g of dry nitrocellulose in 100 cc of butyl acetate) for 5.2 seconds (measured at a solid content of 30%).

Nitro-cellulose brands that meet these conditions are listed as HIG1 / 16, HIG1 / 8, HIG1 / 4, HIG1 / 2, HIG1, H
IG2, HIG7, HIG20, HIG60, HIG120, HIG500, LIG1 / 8, L
IG1 / 4, LIG1 / 2, SL-1, HI1000, HI2000, clear H1 /
4, chip H1 / 2, etc. [all manufactured by Asahi Kasei Corporation].

These resins are not limited to one kind alone, and two or more kinds can be used in combination.

The weight ratio of the acetal-based resin to nitrocellulose in the ink layer is usually in the range of 20:80 to 90:10, preferably 50:50 to 85:15.

In the present invention, the following resins can be used as arbitrary binder components in addition to the above two resins.

That is, as the optional binder component, for example, an acrylic resin, a methacrylic resin, a polycarbonate, a polyvinyl alcohol, a polyvinyl formal, a polyvinyl ether, a polyvinyl pyrrolidone, a polystyrene, a polystyrene copolymer, an ionomer resin, and a cellulose resin other than nitrocellulose (for example, Ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose,
Methylcellulose, cellulose acetate, cellulose acetate butyrate) and the like.

In this case, the content of the resin as an optional binder component is usually in a range of 50% by weight or less based on the total amount of the resin in the ink layer.

If the content exceeds 50% by weight, the effect of the present invention may not be obtained.

The weight ratio of the binder and the heat-diffusing dye in the ink layer is preferably from 1:10 to 10: 1.

As described above, when an acetal resin and nitrocellulose are used as essential binders of the ink layer, the thermal transfer recording ink sheet has improved storage stability, and the background of the thermal transfer recording image receiving sheet has a reduced background density and reduced image density. In addition to this, the occurrence of fusion with the image receiving sheet for thermal transfer recording is also prevented.

Additives 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, and peelable compounds such as waxes,
Fillers such as metal fine powder, silica gel, carbon black, and resin fine powder, and curing agents (for example, radiation-active compounds such as isocyanates, acryls, and epoxies) that can react with a binder component can be given.

Further, a heat-fusible substance for promoting transfer, such as wax and higher fatty acid 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 additive.

Formation of Ink Layer The ink layer is prepared by dispersing or dissolving the binder and the heat-diffusible dye, and optionally added optional components in a solvent, to prepare an ink layer-forming coating solution. On a support and dried.

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 latex.

Examples of the solvent include water, alcohols (eg, methanol, ethanol, propanol), esters (eg, methyl acetate, ethyl acetate, isopropyl acetate, and acetic acid n).
-Butyl, amyl acetate, ethyl lactate, cellosolve lactate, etc.), cellosolves (eg, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc.), aromatics (eg, toluene, xylene, chlorobenzene, etc.), ketones (eg, acetone) , Methyl ethyl ketone, etc.), ethers (eg, tetrahydrofuran, dioxane, etc.), chlorinated solvents (eg, chloroform, trichloroethylene, etc.), etc., can be used alone or in an appropriate combination of two or more. .

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-As the support used in the present invention, any material can be used as long as it has good dimensional stability and can withstand heat during recording with a thermal head. Examples thereof include condenser paper, thin paper such as glassine paper, and polyethylene. Heat-resistant plastic films such as terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyamide, polycarbonate, polysulfone, polystyrene, and polyimide are suitable.

 Generally, 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, the diffusion of the heat diffusing dye from the ink layer to the image receiving layer is inhibited, and a sufficient image density is obtained. It is not preferable because it becomes difficult.

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

Further, by forming perforations on the thermal transfer recording ink sheet or providing detection marks for detecting the positions of areas having different hues, convenience in use can be achieved.

(II) Thermal transfer recording image receiving sheet The thermal transfer recording image receiving sheet can be composed of a base material 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 comprising the self-supporting image-receiving layer, the base material is not particularly used, so that 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.

Binder for image receiving layer Examples of the binder for image receiving layer include polyvinyl chloride resin, copolymer resin of vinyl chloride and another monomer (for example, vinyl acetate, etc.), chlorinated polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin. , Ketone resin, alkyd resin, polyester resin, acrylate, 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 and the like can be mentioned. These may be used singly,
Two or more can be used in combination. Among them, preferred are vinyl chloride-vinyl acetate copolymer resin, polyvinyl chloride resin, polyester resin and the like.

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

For example, commercially available polyester resins include Byron
200, Byron 290, Byron 600, etc. [all, manufactured by Toyobo Co., Ltd.], KA-1038C [Arakawa Chemical Co., Ltd.], TP220,
TP235 [all manufactured by Nippon Gosei Co., Ltd.] and the like can be used.

The vinyl chloride-vinyl acetate copolymer resin has a vinyl chloride component content of 50 to 100% by weight and a degree of polymerization of 50 to 250.
About 0 is preferable.

The vinyl chloride-vinyl acetate copolymer resin preferably used in the present invention does not necessarily need to be composed only of a vinyl chloride component and a vinyl acetate component, and a vinyl alcohol component and a maleic acid as long as the object of the present invention is not impaired. It may contain a component, a sulfonic acid component, an epoxy component, a glycidyl component, a carboxyl component, and the like. Examples of such a vinyl chloride-vinyl acetate copolymer include, for example, S-lec A, S-lec C, S-lek M (all manufactured by Sekisui Chemical Co., Ltd.), vinylite VACH, vinylite VYHH, vinylite VMCH, vinylite VYHD, vinylite VYLF, Vinylite VYNS, Vinylite VMCC, Vinylite
VMCA, vinylite VACD, vinylite VERR, vinylite VR
OH (all manufactured by Union Carbide), Denka Vinyl 10
00GKT, DENKAVINYL 1000L, DENKAVINYL 1000CK, DENKAVINYL 1000A, DENKAVINYL 1000LK _2, DENKAVINYL 10
00AS, DENKAVINYL 1000MT _2, DENKAVINYL 1000CSK, DENKAVINYL 1000CS, DENKAVINYL 1000GK, DENKAVINYL
1000GSK, Denka Vinyl 1000GS, Denka Vinyl 1000LT ₃ ,
Denka Vinyl 1000D, Denka Vinyl 1000W [all manufactured by Denki Kagaku Kogyo KK] and the like.

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, in particular, resins in the range of 30 to 120 ° C. are preferable, and from the viewpoint of molecular weight, Mw is 2000 to 100,
Resins in the range of 000 are preferred.

In forming the image receiving layer, the above various resins are crosslinked by radiation, heat, moisture, a catalyst, or the like by utilizing their reactive active points (if there is no reactive active point, it is applied to the resin). Alternatively, it may be cured.

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

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 thermal solvent or the like may be added as a sensitizer. These are appropriately used in consideration of compatibility with the binder, storage stability of the image, and the like.

The release agent can improve the releasability between the thermal transfer recording ink sheet and the thermal transfer recording image receiving sheet.

Examples of such release agents include solid waxes such as silicone oil, polyethylene wax, amide wax, and Teflon powder; fluorine-based and phosphate-based surfactants; and among them, 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, it is preferable to use a modified silicone oil as the 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, etc. of siloxane and polyester moieties can also be used as modified silicone oils or resins.

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-1-204
Examples of the compounds include compounds described in 788 and known compounds for improving 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 ligell, calcium carbonate, titanium oxide, acid clay, activated clay, and alumina.Examples of the organic fine particles include fluorine resin particles,
Resin particles such as guanamine resin particles, acrylic resin particles, and silicon resin particles can be used. These inorganic and organic resin particles vary depending on the specific gravity.
Is preferred.

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 and the thermal solvent include phthalic esters (for example, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, didecyl phthalate, etc.) and adipic esters (dioctyl adipate, methyl lauryl adipate, di-adipate). 2-ethylhexyl, ethyl lauryl adipate, etc.), other oleates, succinates, maleates, sebacates, citrates, epoxystearate epoxies, and triphenyl phosphate And glycol esters such as ethyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate.

In the present invention, the amount of the additive as a whole is usually in the range of 0.1 to 50% by weight based on the binder for the image receiving layer.

Formation of the image receiving layer The image receiving layer is prepared 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, It can be formed by a coating method of drying, a lamination 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 methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, aromatics such as toluene and xylene, esters such as ethyl acetate and butyl acetate, ethers such as diethyl ether, tetrahydrofuran and dioxane. And alcohol solvents such as methyl alcohol, ethyl alcohol and isopropanol, and halogen solvents such as dichloromethane and trichloroethylene.

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 3 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 laminating them with paper), white polyethylene terephthalate base film, transparent polyethylene terephthalate base film, polyolefin coating. Paper etc. can be mentioned.

The thickness of the substrate is usually 30 to 300 μm, preferably 80 to 200
μm.

-Other layers- An overcoat layer may be laminated on the surface of the image receiving sheet for thermal transfer recording for the purpose of preventing fusion with the ink layer and improving image storability. This layer can be formed by an existing coating method such as gravure coating, wire bar coating, roll coating, or a laminating method.

 The thickness of this layer is usually from 0.05 to 5 μm.

In addition, a cushion layer can 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.

(III) Formation of Image To form an image, the ink layer surface of the ink sheet for thermal transfer recording of the present invention and the image receiving layer surface of the image receiving sheet for thermal transfer recording are overlapped so as to be in contact with each other. Apply heat energy 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, by sequentially replacing the thermal transfer recording ink sheets of yellow, magenta, cyan, and, if necessary, black, and performing thermal transfer according to each color, a color image of a color photograph composed of a combination of each color can be obtained.

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

That is, a thermal transfer recording ink sheet having areas formed by applying different colors in advance is prepared, first, a yellow color separation image is thermally transferred using the yellow area, and then magenta color separation is performed using the magenta area. Heat transfer the image,
Thereafter, by repeating this operation sequentially, yellow,
The magenta, cyan and, if necessary, black and color separation images are thermally transferred.

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 A coating liquid for forming an ink layer having the following composition was applied to a corona-treated surface of a polyethylene terephthalate film having a thickness of 9 μm as a support by a wire bar coating method so that the thickness after drying became 1 μm. After drying, apply one or two drops of silicone oil [X-41, 4003A, manufactured by Shin-Etsu Silicone Co., Ltd.] on the back surface that has not been corona-treated and spread it over the entire surface. An ink sheet was obtained.

Coating solution for forming ink layer Disperse dye [Kayaset Blue 136 manufactured by Nippon Kayaku Co., Ltd.] 4 parts Nitrocellulose [viscosity 3.0-4.9 seconds, nitrogen content 11.5-1]
2.2%, degree of polymerization 80-95, trade name HIG1 / 2, Asahi Kasei Corporation
1.5 parts polyvinyl butyral [degree of polymerization 300, degree of acetalization 6]
3 ± 3 mol% or more, acetyl group 3 mol% or less, Tg59.2
° C, trade name BL-1, manufactured by Sekisui Chemical Co., Ltd.] 3.5 parts Toluene 40 parts Methyl ethyl ketone・ ・ 40 parts Dioxane ・ ・ ・ ・ 10 parts Next, synthetic paper with a thickness of 150 μm [trade name Yupo F
PG-150; manufactured by Oji Yuka Synthetic Paper Co., Ltd.], a coating solution for forming an image receiving layer having the following composition is applied by a wire bar coating method, and further temporarily dried by a drier, and then heated to 100 ° C.
Dry in an oven for 1 hour and place on a synthetic paper about 10μ thick.
Thus, an image receiving sheet for heat-sensitive transfer recording, which is formed with an m image receiving layer was obtained.

Coating solution for forming image receiving layer Polyester resin [Byron 103, Toyobo Co., Ltd.
, Tg: 47 ° C] ... 10 parts Amino-modified silicone oil [KF393, manufactured by Shin-Etsu Silicone Co., Ltd.] 0.125 parts Epoxy-modified silicone oil [X-22-343, Shin-Etsu Silicone Co., Ltd.] 0.125 parts Toluene 57 parts Xylene 13 parts Methyl ethyl ketone ... 6.3 parts 2-butanol 14 parts Cyclohexanone 30 parts Next, the thermal transfer obtained as described above After storing the recording ink sheet at 60 ° C. for 8 days, the sheet and the heat-sensitive transfer recording image-receiving sheet are overlapped so that the former ink layer surface and the latter image-receiving layer surface are in contact with each other. 0.35W / dot output and dot density 8 dots from the support side using a thermal head The image was recorded by heating under the condition of ト / mm.

After image recording, background stain on an unprinted portion (white background) of the image receiving layer surface of the thermal transfer recording image receiving sheet, transfer density of the image receiving layer surface, fusion of the thermal transfer recording ink sheet and the thermal transfer recording image receiving sheet. The condition was 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 density was sufficient.

 X: The concentration was low.

Fusing: ・: Only the dye was transferred to the image receiving layer, and the heat layer of the ink was peeled off from the support.

 X: The entire ink layer was transferred to the image receiving layer.

(Example 2) In Example 1, polyvinyl butyral, which is one of the components of the coating liquid for forming an ink layer, was converted to polybutylacetoacetal [degree of polymerization: about 2400, degree of acetalization: 70 mol% or more, acetyl group: 3 mol% Hereinafter, Tg110 ° C. or higher, KS-5z, manufactured by Sekisui Chemical Co., Ltd.], except that the operation was performed in the same manner as in Example 1.

 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 composition of the coating solution for forming an image receiving layer was changed as follows.

 The results are shown in Table 1.

Coating solution for forming image receiving layer Vinyl chloride-vinyl acetate copolymer resin [Polymerization degree 410, VY
HH Union Carbide Co.] 10 parts Methyl ethyl ketone 100 parts Cyclohexanone 50 parts (Comparative Example 1) Coating for forming ink layer in Example 1 The procedure was performed in the same manner as in Example 1 except that nitrocellulose, one of the components of the working solution, was replaced with polyvinyl butyral.

 The results are shown in Table 1.

(Comparative Example 2) In Example 1, nitrocellulose, one of the components of the coating liquid for forming an ink layer, was replaced with ethylcellulose [trade name: EC
N-14 Hercules Co.] was carried out in the same manner as in Example 1.

 The results are shown in Table 1.

(Comparative Example 3) The same operation as in Example 1 was performed except that polyvinyl butyral, one of the components of the coating liquid for forming an ink layer, was replaced with nitrocellulose. 5 copies).

 The results are shown in Table 1.

[Effect of the Invention] The ink sheet for thermal transfer recording of the present invention has improved storage stability, prevents fusion with the image receiving sheet for thermal transfer recording, prevents generation of background stain on the sheet, and reduces image density. Reduction can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an ink sheet for thermal transfer recording of the present invention. 1 ... support, 2 ... ink layer.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-10087 (JP, A) JP-A-64-1971 (JP, A) JP-A-63-168394 (JP, A) JP-A-3-3 19894 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] A heat-diffusible dye, an acetal resin and nitrocellulose, wherein the weight ratio of the acetal resin to nitrocellulose (acetal resin / nitrocellulose) is 50/50 to 85/15. An ink sheet for thermal transfer recording, wherein the ink layer is laminated on a support.