JP3100616B2 - 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 excellent in storage stability and dye transferability.

[Prior Art and Problems to be Solved by the Invention] As a method of obtaining a color hard copy, a color recording technique using ink jet, electrophotography, thermal transfer, and the like has been conventionally 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 over time and accumulates on the surface of the ink layer, and migrates to the back of the sheet with which it is in contact. May be contaminated (dirt).

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

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

The present invention has been made to improve the above situation.

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 object, a polyvinyl acetoacetal resin having a polymerization degree of 1500 or more and an acetoacetalization degree of less than 80%, and a polymerization degree of 1500 or more Wherein the ink layer contains a polyvinyl butyral resin and a heat diffusible dye on a support.

 Hereinafter, the present invention will be described in detail.

[1.] Thermal transfer recording ink sheet The thermal transfer recording ink sheet of the present invention basically has a structure in which an ink layer is provided on a support.

—Ink Layer— The ink layer contains a binder and a heat-diffusing dye as described below.

1. Heat-diffusing dyes Heat-diffusing dyes include cyan dyes, magenta dyes, and yellow dyes.

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.

Particularly preferred as the thermal diffusible dye is a compound having an open-chain or closed-type active methylene group obtained by a coupling reaction with an oxidized p-phenylenediamine derivative or an oxidized p-aminophenol derivative. An indoaniline dye obtained by a coupling reaction with an azomethine dye and an oxidized form of a phenol or naphthol derivative or a p-phenylenediamine derivative or an oxidized form of a p-aminophenol derivative.

The thermal diffusible dye contained in the ink layer 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 dyes or other heat-diffusible dyes may be contained.

The amount of the heat diffusible dye to be used is generally 0.1 to ²⁰ g, preferably 0.2 to 5 g, per 1 m2 of the support.

2. Binder In the present invention, it is important to use a polyvinyl acetoacetal resin and a polyvinyl butyral resin as a binder for the ink layer.

That is, when these resins are used as a binder, the thermal transfer recording ink sheet has improved storage stability,
Dye transferability is also improved.

The polyvinyl acetoacetal resin and the polyvinyl butyral resin used in the present invention preferably have a degree of polymerization of 1,500 or more.

If the degree of polymerization is less than 1,500, the storage stability is poor, and the transfer density may decrease over time, and background fouling may occur.

Further, the polyvinyl acetoacetal resin preferably has a degree of acetoacetalization of less than 80%.

If the degree of acetoacetalization exceeds 80%, a sufficient transfer density may not be obtained.

In the present invention, the weight ratio of the polyvinyl acetoacetal resin and the polyvinyl butyral resin can be arbitrarily set as long as both resins coexist. Acetal resin: Polyvinyl butyral resin is usually 1
0:90 to 90:10, preferably 40:60 to 90:10.

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

In the present invention, the resins listed above as binders can be used in combination with other resins used in the thermal transfer recording field.

Examples of other resins mentioned herein 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 pyrrolidone, polyester, polyvinyl acetate, and polyvinyl acetate. Acrylamide, styrene resin, styrene copolymer resin, rubber resin, ionomer resin, olefin resin and the like can be mentioned.

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

The weight ratio of the polyvinyl acetoacetal resin and / or the polyvinyl butyral resin to the other resin is usually 100: 0 to 50:50, preferably 90:10 to 60:40.

3. Additives Various additives can be added to the ink layer as long as the object of the present invention is not impaired.

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, metal oxide, 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 may be mentioned. it can.

Still further, as an additive, a compound described in JP-A-59-106997, such as a heat-fusible substance for promoting transfer, such as a wax or a higher fatty acid ester, may be used.

-Support-The support used in the present invention has good dimensional stability and can withstand heat during recording with a thermal head.
Any material can be used, and heat-resistant plastic films such as thin paper such as condenser paper and glassine paper, polyethylene terephthalate, polyethylene naphthalate, polyamide, polycarbonate, polysulfone, polyvinyl alcohol cellophane, and polystyrene can be used.

The thickness of the support is preferably 2 to 10 μm, and the support may have an undercoat layer for the purpose of improving adhesion to a binder or transferring a dye to the support, or preventing dyeing. Good.

Further, a sticking prevention layer may be provided on the back surface of the support (on the side opposite to the heat-sensitive layer) for the purpose of preventing the head from sticking, sticking or wrinkling to the support.

The thickness of the anti-sticking layer is usually 0.1 to 1 μm.
m.

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

[2.] Production of Thermal Transfer Recording Ink Sheet The thermal transfer recording ink sheet is prepared by dispersing or dissolving the above-mentioned various components forming an ink layer in a solvent to prepare an ink layer forming coating liquid. On the surface of a support and dried.

The binder is used by dissolving one kind or two or more kinds in a solvent or dispersing it in a latex form.

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

For the coating, a conventionally known gravure roll can be employed such as a face-to-face coating method, an extrusion coating method, a wire bar coating method, a roll coating method, or the like.

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

Further, in addition to the three ink layers arranged along the planar direction, a black ink layer containing a black image forming substance,
It may be interposed.

Regarding the black ink layer, a clear image can be obtained by either the diffusion transfer type or the melt transfer type.

The thickness of the ink layer thus formed is usually 0.2 to 1
0 μm, preferably 0.3 to 3 μm.

In the present invention, the ink sheet for thermal transfer recording may be provided with a perforation or provided with a detection mark for detecting the position of an area having a different hue, thereby facilitating use.

Note that the ink sheet for thermal transfer recording is not limited to the configuration including the support and the thermal layer formed thereon, and other layers may be formed on the surface of the ink layer.

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

[3.] Image-receiving sheet for thermal transfer recording An image-receiving sheet for thermal transfer recording is also required for thermal transfer recording (image formation).

The image receiving sheet for thermal transfer recording 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 of a self-supporting image receiving layer.

In the heat-sensitive transfer recording image-receiving sheet including the self-supporting image-receiving layer, the number of components can be reduced since no base material is used.

-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, it can be formed only from the binder for the image receiving layer.

1. Binder for image receiving layer As binder for image receiving layer, polyester resin, polyvinyl chloride resin, vinyl chloride copolymer (for example, vinyl chloride-alkyl vinyl ether copolymer), acrylate, polyvinylpyrrolidone, polycarbonate, cellulose triacetate , Styrene-acrylate resin,
Examples thereof include a vinyl toluene-acrylate resin, a polyurethane resin, a polyamide resin, a urea resin, a polycaprolactone resin, a styrene-maleic anhydride resin, a polyvinyl chloride resin, and a polyacrylonitrile resin.

Among these, preferred are vinyl chloride-alkyl vinyl ether copolymer, vinyl chloride-vinyl acetate copolymer, polyester resin, polyvinyl chloride resin and the like.

Although the various resins may be newly synthesized and used,
Commercial products can also be used.

In any case, from the viewpoint of physical properties, as another resin for the image receiving layer, particularly a resin having a Tg of −20 to 150 ° C., and a Tg of 4
Resins that are between 0 and 120 ° C are preferred.

The binder for the image receiving layer has a molecular weight of 2,000 to 1
Preferably it is 00,000.

If the above various resins have reactive active sites, the reactive active sites may be used, or if there is no reactive active site, they may be imparted and crosslinked or cured by radiation, heat, moisture 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 between the thermal transfer recording ink sheet and 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 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. 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 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), other oleates, succinates, maleates, sebacates, citrates, epoxidized soybean oil, epoxidized linseed oil , Epoxystearate epoxys, and orthophosphoric esters such as triphenyl phosphate and tricresyl phosphate; and phosphites such as triphenyl phosphite, tris tridecyl phosphite, and dibutyl hydrogen phosphite. And glycol esters such as ethylphthalylethyl glycolate and butylphthalylbutyl 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 image receiving layer.

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

[4.] Production of heat-sensitive transfer recording image-receiving sheet The heat-sensitive transfer recording image-receiving sheet 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. It can be manufactured by a coating method in which a working liquid is applied to the surface of a substrate and dried.

Alternatively, it can be produced by a lamination method or the like in which a mixture having a component for forming the image receiving layer is melt-extruded and laminated on the surface of a substrate.

As the solvent used in the coating method, water, alcohol,
Conventionally known solvents such as methyl ethyl ketone, toluene, dioxane and cyclohexanone can be mentioned.

When employing the lamination method, 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 of the substrate.

The thickness of the image receiving layer formed on the surface of the substrate is generally 2 to
It is 50 μm, preferably about 3 to 20 μm.

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

In this thermal transfer recording image-receiving sheet, in order to more effectively prevent fusion with the ink layer of the thermal transfer recording ink sheet, a release material (the above-mentioned,
A release layer containing a silicone resin, a modified silicone resin, a silicone oil film or a cured product thereof may be further laminated.

 The thickness of the release layer is usually from 0.03 to 2.0 μm.

Further, in the image receiving sheet for thermal transfer recording of the present invention, a cushion layer may be provided between the substrate and the image receiving layer.

By providing the cushion layer, it is possible to transfer and record an image corresponding to image information with good reproducibility with little noise.

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 usually 1 to 50 μm, preferably 3 to 30 μm.

[5.] Formation of Image (Thermal Transfer Recording) To form an image, the ink layer of the thermal transfer recording ink sheet and the image receiving layer of the thermal transfer recording image receiving sheet are overlapped, and an interface between the ink layer and the image receiving layer is formed. Gives image-wise thermal energy.

Then, 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 side and received.

 As a result, an image is formed on the image receiving layer.

In the present invention, since the ink layer of the ink sheet for thermal transfer recording contains the specific binder as described above, the transferability of the dye to the image receiving sheet for thermal transfer recording is excellent, and the light -It is possible to prevent discoloration change, bleeding, dye bleed-out, etc. of an image due to heat or the like.

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

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 applying heat energy, the applied heat energy can be changed by changing the light amount or irradiation area of the laser light.

In this case, in order to easily absorb the laser light, a laser light absorbing material (for example, 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.

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

When a laser beam is used, the thermal transfer recording ink sheet and the thermal transfer recording image receiving sheet may be sufficiently adhered to each other.

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

Alternatively, heating may be performed via a pattern or a halftone pattern that continuously expresses the shading of an image, such as black, or a negative pattern corresponding to a negative of the above-described pattern with a colored layer such as black on one surface. Heating may be performed in combination.

The method of applying thermal energy may be performed from the thermal transfer recording ink sheet side, may be performed from the thermal transfer recording image receiving sheet side, or may be performed from both sides, but if priority is given to the effective use of thermal energy, It is desirable to perform the heat transfer recording from the ink sheet side.

By the above-described thermal transfer recording, a one-color image can be recorded on the image receiving layer of the thermal transfer recording 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, if the thermal transfer sheets for yellow, magenta, cyan, and black, and black as required, are sequentially replaced and thermal transfer is performed for each color, a color photographic color image composed of a combination of each color can be obtained.

 Then, the following method is also effective.

That is, instead of using the thermal transfer recording ink sheet of each color as described above, a thermal transfer recording ink sheet having an area previously formed separately for each color is used.

Then, first, the yellow color separation image is thermally transferred using the yellow area, then the magenta color separation image is thermally transferred using the magenta area, and thereafter, yellow, magenta, cyan, and necessary A method in which thermal transfer is sequentially performed with a black color separation image.

With this method, a color photographic color image can be obtained. However, more advantageously, this method has an advantage that the above-mentioned replacement of the heat-sensitive transfer recording heat-sensitive sheet is unnecessary.

[Examples] Next, the present invention will be described more specifically with reference to examples and comparative examples.

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

(Example 1) A coating liquid for forming an ink layer having the following composition was dried on a corona-treated surface of a polyethylene terephthalate film (manufactured by Toray Industries, Ltd.) having a thickness of 6 μm as a support by a wire bar coating method, and dried. And a silicone oil [X-X, manufactured by Shin-Etsu Silicone Co., Ltd.] on the back surface not subjected to corona treatment.
41, 4003A] was dropped over a drop with one or two drops with a dropper and spread over the entire surface, and a back surface treatment coating was performed to obtain an ink sheet for thermal transfer recording.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] 4 parts polyvinyl acetoacetal resin [degree of polymerization 2400, acetoacetalization degree: 50% by weight] 2 parts polyvinyl butyral resin [degree of polymerization 1700, product Name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.] 2 parts Methyl ethyl ketone 90 parts Cyclohexanone 10 parts Next Then, a coating liquid for forming an image receiving layer having the following composition was applied onto a 150 μm-thick synthetic paper [Yupo FPG-150, manufactured by Oji Oil Chemicals Co., Ltd.] as a base material by a wire bar coating method, and further dried with a dryer. After the preliminary drying, the resultant was dried in an oven at a temperature of 100 ° C. for 1 hour to obtain an image receiving sheet for thermal transfer recording in which an image receiving layer having a thickness of 5 μm was formed on synthetic paper.

Coating solution for forming image receiving layer PVC-isobutyl ether copolymer (manufactured by BASF, Laro
flex-MP25) 9 parts polyester modified silicone resin [Shin-Etsu Silicon Co., Ltd.
X-24-8300] 1 part methyl ethyl ketone 40 parts Next, the ink sheet for thermal transfer recording and the image receiving sheet for thermal transfer recording were combined with the former ink. The surface of the layer and the surface of the image receiving layer are overlapped so that they contact each other, and the output is 0.4 W / dot, the pulse width is 0.3 to 10 msec, and the dot density is 6 using a thermal head from the support side of the thermal transfer recording ink sheet
The image was recorded by heating under the condition of dots / mm.

After image recording, the transferability of the heat diffusible dye to the image receiving layer (transfer density) and the storage stability of the ink sheet for thermal transfer recording (ground stain) 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 density was sufficient.

 X: The concentration was low.

(Example 2) The same procedure was performed as in Example 1 except that the coating liquid for forming an ink layer in Example 1 was changed to the following composition.

 The results are shown in Table 1.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] 4 parts polyvinyl acetoacetal resin [degree of polymerization 2400, degree of acetoacetalization: 70% by weight] 2 parts polyvinyl butyral resin [degree of polymerization 1700, product Name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.] 2 parts Methyl ethyl ketone 90 parts Cyclohexanone 10 parts ( Example 3 The same operation as in Example 1 was performed except that the coating liquid for forming an ink layer in Example 1 was changed to the following composition.

 The results are shown in Table 1.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] 4 parts polyvinyl acetoacetal resin [degree of polymerization 2400, degree of acetoacetalization: 70% by weight] 2 parts polyvinyl butyral resin [degree of polymerization 1700, product Name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.] 1 part Nitrocellulose [trade name: Cellnova BTH-1 / 2, manufactured by Asahi Kasei Corporation] ··· Methyl ethyl ketone ······ 90 parts Cyclohexanone ········ 10 parts (Comparative Example 1) The coating liquid for forming an ink layer in Example 1 had the following composition. Except for the above, the procedure was the same as in Example 1.

 The results are shown in Table 1.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] ··· 4 parts Polyvinyl acetoacetal resin [Polymerization degree 500, trade name: Esrec KS-1 manufactured by Sekisui Chemical Co., Ltd.] ··· 2 parts Polyvinyl butyral resin [Polymerization degree 800, trade name: Denkabutyral ^# 3000-K, manufactured by Denki Kagaku Kogyo KK] 2 parts methyl ethyl ketone 90 parts cyclohexanone ... 10 parts (Comparative Example 2) The same operation as in Example 1 was performed, except that the coating liquid for forming an ink layer in Example 1 was changed to the following composition.

 The results are shown in Table 1.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] ... 4 parts Polyvinyl acetoacetal resin [Polymerization degree 2400, trade name: Esrec KS-5 Acetalization degree 90% or more, manufactured by Sekisui Chemical Co., Ltd.] 2 parts polyvinyl butyral resin [degree of polymerization 1700, trade name ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.] 2 parts methyl ethyl ketone 90 parts cyclohexanone ... 10 parts (Comparative Example 3) The same operation as in Example 1 was performed except that the coating liquid for forming an ink layer in Example 1 was changed to the following composition.

 The results are shown in Table 1.

Coating liquid for forming ink layer Disperse dye [Kayaset Blue 13 manufactured by Nippon Kayaku Co., Ltd.]
6] ... 4 parts Polycarbonate resin [Macrolon 5705 manufactured by Bayer AG] ... 4 parts Methylene chloride-trichloroethylene mixed solvent ... 100 parts [Effect of the Invention] The ink sheet for thermal transfer recording of the present invention is excellent in the storability of the sheet itself and the transferability of the dye to the ink sheet for thermal transfer recording.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-233294 (JP, A) JP-A-3-65395 (JP, A) JP-A-63-151485 (JP, A) JP-A-2- 297488 (JP, A) JP-A-4-22685 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. An ink layer containing a polyvinyl acetoacetal resin having a degree of polymerization of 1500 or more and an acetoacetalization degree of less than 80%, and a polyvinyl butyral resin having a degree of polymerization of 1500 or more and a heat diffusible dye. An ink sheet for thermal transfer recording, which is provided on a support.