JPH08175037A - Thermal transfer sheet and thermal transfer recording method using the same - Google Patents

Abstract

PURPOSE: To provide a thermal transfer sheet having excellent releasability with respect to a vinyl chloride type receiving material and excellent in preservability. CONSTITUTION: A thermal transfer sheet 5 is obtained by providing a dye layer 2 containing a thermal transfer dye and a binder on a base material film 1 and forming a releasable film 4 with a thickness of 10<-3> -1μm composed of a water-soluble resin on the dye layer 2 and an image is formed on a receiving material composed of a vinyl chloride resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet, and in particular, it has excellent releasability for a receptor made of vinyl chloride resin, and when dyed and stored, the dye migrates to the back layer side (so-called backside). The present invention relates to a thermal transfer sheet capable of preventing movement.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known,
Among them, a transfer sheet in which a dye layer containing a sublimable dye and a binder is provided on a substrate film is used, and the dye in the dye layer is sublimated (heated by a heating means such as a thermal head or laser according to image information). A sublimation-type thermal recording method is known in which recording is performed on the transferred material after the transfer. The thermal transfer sheet used in the sublimation type thermal recording method has a dye layer containing a sublimable dye formed on one surface of a substrate film such as a polyester film and prevents sticking with a thermal head on the other surface. Therefore, those provided with a heat resistant slipping layer are generally used. Since such a thermal transfer recording system can form a full-color image very easily, it is widely used to provide a face photograph or the like on a plastic card such as an ID card or a members card.

[0003]

However, such a plastic card is often not treated specially, and for high-speed printing, the heating of the thermal head takes a very short time (msec unit). ) And high temperature is required, so if the temperature of the thermal head is raised,
The binder forming the dye layer softens, causing the inconvenience of fusing the thermal transfer sheet and the plastic card. In an extreme case, the dye layer peels off from the base film when they are peeled off and the surface of the image receiving sheet remains as it is. There was a problem of being transferred to. Also, the thermal transfer sheet is usually
The back heat resistant slipping layer and the dye layer are applied, dried, and then wound up and slit into a predetermined width, but the same binder resin is used for the resin binder and the dye layer binder constituting the heat resistant slip layer, or the dye layer If the binder and dye have poor compatibility,
In the wound state, there is a problem that the dye deposited from the dye layer migrates to the heat resistant slipping layer side. Therefore,
An object of the present invention is to solve the above problems and provide a thermal transfer sheet having excellent releasability with respect to a vinyl chloride type receptor and excellent storage stability.

[0004]

[Means for Solving the Problems] As a result of intensive research conducted by the present inventors in order to solve the above problems, a thermal transfer sheet having particularly excellent releasability for a receptor made of vinyl chloride resin was found. . That is, the invention of claim 1 is such that a dye layer containing a heat transferable dye and a binder is provided on a substrate film, and a separation layer made of a water-soluble resin and having a thickness of 10 ⁻³ to 1 μm is provided on the dye layer. A thermal transfer sheet for forming an image on a receiver made of a vinyl chloride resin, on which a moldable film is formed. The invention of claim 2 is the thermal transfer sheet according to claim 1, wherein the releasable coating made of a water-soluble resin is a continuous coating. The invention of claim 3 is the thermal transfer sheet according to claim 1, wherein the releasable film made of a water-soluble resin is a discontinuous film. The invention of claim 4 is the thermal transfer sheet according to claim 1, wherein the release film and the dye layer binder are made of the same type of resin. The invention of claim 5 is the thermal transfer sheet according to claim 1, wherein the water-soluble resin is formed of at least one of polyvinyl alcohol, polyvinyl acetal, and water-soluble cellulose resin. The invention of claim 6 is the thermal transfer sheet according to claim 1, wherein the polyvinyl alcohol content of the polyvinyl acetal is 80% by weight or more and less than 100%. The invention according to claim 7 is the thermal transfer sheet according to any one of claims 1 to 8, wherein the release film contains a surfactant.
The invention of claim 8 is the thermal transfer sheet according to claim 1, wherein the content of the surfactant is 50 to 200 parts by weight with respect to the solid content of the water-soluble resin.

In the invention of claim 9, a dye film containing a heat transferable dye and a binder, and a releasable film made of a water-soluble resin and having a thickness of 10 ⁻³ to 1 μm are laminated on a substrate film. A thermal transfer recording characterized in that an image is formed on the receptor by superposing a thermal transfer sheet composed of the above and a receptor made of vinyl chloride resin and heating the dye according to image information to transfer the dye thermally. Is the way. The invention according to claim 10 is the thermal transfer recording method according to claim 9, wherein the releasable film made of a water-soluble resin is a continuous film. The invention according to claim 11 is the thermal transfer recording method according to claim 9, characterized in that the release film made of a water-soluble resin is a discontinuous film. The invention of claim 12 is
10. The thermal transfer recording method according to claim 9, wherein the water-soluble resin is formed of at least one of polyvinyl alcohol, polyvinyl acetal, and water-soluble cellulose resin. According to the invention of claim 13, the polyvinyl alcohol content of the polyvinyl acetal is 80% by weight or more.
The thermal transfer recording method according to claim 9, wherein the thermal transfer recording method is less than 00%. A fourteenth aspect of the present invention is the thermal transfer recording method according to the ninth to thirteenth aspects, wherein the film made of a water-soluble resin contains a surfactant. In the invention of claim 15, the content of the surfactant is
16. The thermal transfer recording method according to claim 15, wherein the amount is 50 to 200 parts by weight based on the solid content of the water-soluble resin. A sixteenth aspect of the present invention is the thermal transfer recording method according to the ninth aspect, wherein the receptor is a card. The invention according to claim 17 is the thermal transfer recording method according to claim 9, characterized in that the receptor comprises a substrate on which a receptor layer made of vinyl chloride or a vinyl chloride-vinyl acetate copolymer resin is provided. is there.

[0006]

[Function] Even when printing is performed by combining a thermal transfer sheet having a water-soluble resin film having a thickness of 10 ^-3 to 1 μm on a dye layer and a receiver made of vinyl chloride resin, thermal fusion or abnormal transfer ( It is possible to obtain an image having a good print density without causing the phenomenon that the dye layer is peeled off and transferred to the receptor together with the dye layer). It is considered that this is because the water-soluble resin has poor compatibility with the vinyl chloride resin and prevents the both from softening and fusing during printing. Further, since a very thin film having a thickness of 10 ⁻³ to 1 μm is formed, the dye permeability is good, and the problem of sensitivity decrease due to the provision of the releasable film is extremely small. Furthermore, even if the compatibility of the dye with the resin binder is not so good, a thin film is formed on the dye layer that does not impair the dye permeability, so the heat-resistant slip layer side during winding storage It is possible to block the transfer of the dye to the.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. (Substrate film) The substrate film used for the thermal transfer film of the present invention may be any one as long as it has a conventionally known degree of heat resistance and strength, for example, 0.5 to 50 μm, preferably Paper with a thickness of about 3 to 10 μm, various processed papers, polyester films including polyethylene terephthalate film, polystyrene film, polypropylene film, polysulfone film, polyphenylene sulfide film, polyethylene naphthalate film, 1,4-polycyclohexylene dimethyl A terephthalate film, an aramid film, a polycarbonate film, a polyvinyl alcohol film, cellophane, and the like, and a polyester film is particularly preferable. These substrate films may be single-wafer type or continuous films and are not particularly limited. Among these, polyethylene terephthalate film is particularly preferable, and it is also preferable to provide an adhesive layer (primer layer) on one or both surfaces of the film, if necessary.

(Heat-resistant slipping layer) The surface of the above-mentioned substrate on which the dye layer is not provided (rear side) prevents fusion with a thermal head, improves runnability, and provides the composite thermal transfer of the present invention. In order to prevent the back surface and the color material layer surface from adhering to each other when the film is wound into a roll, a heat resistant slipping layer provided with heat resistant slipping property and releasability is provided on the back surface side of the base film. Is desirable. Such a heat resistant slipping layer is formed of a release agent such as a curable silicone oil, a curable silicone wax, a silicone resin, a fluororesin or an acrylic resin. In addition, the heat resistant slipping layer has an -OH group or a -CO group.
A thermoplastic resin having an OH group, a compound having two or more amino groups, or a compound obtained by reacting diisocyanate or triisocyanate and crosslinking and curing may be used. Further, slipperiness can be further improved by adding a phosphoric ester type surfactant or a filler having a crushing property such as talc or mica to the heat resistant slipping layer.

(Dye Layer) The dye layer provided in the thermal transfer sheet of the present application is a layer in which a heat transferable dye is carried by an arbitrary binder. As the dye used, heat causes melting,
Dyes that are diffused or sublimated and migrated, and any of the dyes used in conventionally known sublimation transfer type thermal transfer sheets can be effectively used in the present invention, but the hue, light resistance, and solubility in a binder Select in consideration. Preferred dyes include, for example, diarylmethane-based, triarylmethane-based, thiazole-based, methine-based such as merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, imidazoazomethine, azomethine typified by pyridone azomethine, Xanthene-based, oxazine-based, dicyanostyrene, cyanomethylene-based represented by tricyanostyrene, thiazine-based, azine-based, acridine-based, benzeneazo-based, pyridone-azo, thiophenazo, isothiazole-azo, pyrrole-azo, pyral-azo, imidazole-azo, thiadiazole-azo , Azo series such as triazoleazo, diazozo, spiropyran series, indinospiropyran series, fluorane series, rhodamine lactam series, naphthoquinone series, anthraquinone series Include those with quinophthalone.

Specifically, the following dyes are used, for example. CI (Color Index) Disperse Yellow 51,3,54,79,6
0,23,7,141 CI Disperse Blue 24,56,14,301,334,165,19,72,8
7,287,154,26,354, CI Disperse Red 135,146,59,1,73,60,167 CI Disperse Orange 149 CI Disperse Violet 4,13,26,36,56,31 CI Disperse Yellow 56,14,16,29,201,231 CI Solvent Blue 70,35,36,63,36,50,49,111,105,9
7,11 CI Solvent Red 135,81,18,25,19,23,24,143,146,
182 CI Solvent Violet 13,14 CI Solvent Red 135,81,18,25,19,23,24,143,146,
182 CI Solvent Violet 13 CI Solvent Black 3 CI Solvent Green 3

For example, as cyan dyes, Kayaset Blue 714 (Nippon Kayaku, Solvent Blue 63) Foron Brilliant Blue-SR (Sand, Disperse Blue 354), Waxolin AP-FW (ICI, Solvent) Blue 36), MS-REDG as magenta dye
(Mitsui Toatsu Co., Disperse Red 60), Macrolex Violet R (Bayer, Disperse Violet 26), Foron Brilliant Yellow S-6GL as yellow dye (Sand, Disperse Yellow 23)
Dyes such as 1) and Macrolex Yellow 6G (manufactured by Bayer, Disperse Yellow 201) can be used.

As the binder resin for carrying the dye as described above, known binder resins can be used. Examples thereof include cellulose resins such as ethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, polyvinyl alcohol, Examples include vinyl resins such as polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, and polyvinylpyrrolidone, acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide, polyurethane resins, polyamide resins, polyester resins, etc. Alternatively, they can be optionally used by mixing. Among these, polyvinyl acetal resins such as polyvinyl butyral and polyvinyl acetoacetal are preferable from the viewpoints of dye transferability and film storability, and in forming a releasable film made of a water-soluble resin described later.

The dye layer region is preferably a coating liquid prepared by dissolving the above dye and binder resin, if necessary, various additives and dissolving them in an appropriate organic solvent or dispersing them in an organic solvent or water. A gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate and the like by coating means on the base film,
The dye layer can be formed by drying. In this case, the dye layer may be provided by one application, but may be provided by two applications. By forming in this way, the dye concentration per unit area can be increased. The thickness of the dye layer formed as described above is 0.2 to 5.0 μm.
A thickness of m, preferably 0.4-2.0 μm is suitable. Monochromatic printing may be used for this printing, but for the purpose of the present invention, multicolor printing of three colors of yellow, magenta, and cyan, and further four colors including black is preferable so that a color image can be formed. Further, if necessary, a protective layer for transferring to the image after printing may be provided adjacent to the dye layer.

(Release film) The thermal transfer sheet of the present invention comprises:
A film made of a water-soluble resin is formed on the dye layer. This film is a water-soluble resin described below, a coating solution obtained by adding an additive and a solvent for improving coatability to a dye layer by a conventionally known method such as a gravure printing method, a screen printing method, and a bar coater. It is formed by coating on top and drying. It can also be formed by spraying a coating liquid for forming a releasable film on the dye layer. The thickness of the film is 10 ^-3 when dried.
It is characterized by being formed of an extremely thin layer of 1 μm, and even if formed as described above, it is possible to sufficiently permeate the dye, and it is possible to obtain a printed matter of high density. If the thickness is less than the above range, the effect of releasability is not seen, on the contrary, if it is too thick, the dye permeability becomes low, causing a decrease in sensitivity, and there is a problem that a printed matter of sufficient density cannot be obtained. is there. The coating as described above may be a continuous coating or a discontinuous coating such as a mesh or island. Further, the discontinuous film state may be dense or sparse.

As the resin for forming the releasable film, a water-soluble resin having a property of low compatibility with a vinyl chloride resin is preferable. Specifically, polyvinyl alcohol and polyvinyl acetoacetal containing a large amount of polyvinyl alcohol component are preferable. Polyvinyl acetal resin such as polyvinyl butyral and water-soluble cellulose resin such as hydroxypropyl cellulose and ethyl hydroxycellulose may be used alone or in combination of two or more. Among these, preferable resins are polyvinyl alcohol and polyvinyl acetal, and polyvinyl alcohol is more preferable. Polyvinyl alcohol has a molecular weight of 1
Those of 10,000 to 200,000 are preferable. When the molecular weight is less than 10,000, there is a problem of deterioration of coating suitability and deterioration of storage stability. On the other hand, when the molecular weight exceeds 200,000, deterioration of coating suitability and lower dye permeability, resulting in lower sensitivity. There is a risk of doing.

The saponification degree is preferably 80 or more and less than 100.

Among the above resins, as the polyvinyl acetal resin, resins such as polyvinyl acetoacetal and polyvinyl butyral can be used. Among them, those having a particularly high vinyl alcohol content are
It is preferable because it has low compatibility with vinyl chloride and good releasability. The preferable polyvinyl alcohol content in the resin is preferably 80% by weight or more and less than 100%. From the viewpoint of releasability, it is preferable to approach 100% by weight, but when a polyvinyl acetal resin which is excellent as a dye layer binder is used, a releasable film is formed with a polyvinyl acetal resin having a high degree of acetalization. It is preferable to do so in terms of good adhesiveness, and it is desirable to adjust appropriately. Thus, by forming the resin for forming the releasable film and the binder resin for the dye layer with the same type of resin, the adhesiveness to the dye layer can be improved. The molecular weight of the polyvinyl acetal resin is 20,000 to 200,0.
00 is preferable.

By the way, when polyvinyl alcohol or an acetal resin having a high polyvinyl alcohol content is dissolved in water or water / alcohol and applied on the dye layer, the cohesive force of the polyvinyl alcohol itself is strong, and when it is alone, it is 10 ^-3. It is difficult to form a very thin film such as μm. Therefore, a surfactant can be added to the ink for forming the releasable film to improve the coatability. As the surfactant to be used, an anionic surfactant, a cationic surfactant, a nonionic surfactant and the like can be used. Among these, nonionic surfactants such as polyoxyethylene sorbitan monolate and polyoxyethylene fatty acid esters such as polyoxyethylene alkyl ether are particularly preferable. Also, as a solvent to be used,
Although a release film can be formed using water or a water / alcohol mixed solvent, the latter has the advantage of better drying properties. When a surfactant is used in combination, it is desirable that the content of the surfactant is 50 to 200 parts by weight based on the solid content of the water-soluble resin.

(Receptor) The thermal transfer sheet of the present invention as described above is characterized in that it is particularly excellent in releasability with respect to a receptor made of a vinyl chloride resin. Examples of the receptor include a sheet made of a vinyl chloride resin on a base material made of a plastic sheet or paper, a sheet made of a vinyl chloride resin, a card formed by laminating a plurality of the sheets. , Can be used as appropriate. In short, if the dye receiving surface is made of vinyl chloride resin, the effect can be sufficiently exhibited. Preferred vinyl chloride resins used in the present invention include vinyl chloride resins and vinyl chloride-vinyl acetate copolymers. FIG. 2 shows an example of a preferred PVC card 6 used in the present invention, in which transparent polyvinyl chloride layers 8 and 8'are laminated on both surfaces of a polyvinyl chloride center core 7 containing a white pigment. It has a configured configuration. The transparent vinyl chloride layer 8 on the image forming side preferably contains a plasticizer such as DOP, DHP or DBP from the viewpoint of dye dyeing property.

A preferred range of the amount of these plasticizers is 0.1 to 10 parts by weight per 100 parts by weight of polyvinyl chloride forming the dye receiving surface 8, and a particularly preferred range is 3 to 5.
Parts by weight. If the amount of the plasticizer used is too small, the dyeability to the sublimable dye is insufficient.On the other hand, if the amount is too large, the dye receiving surface lacks in rigidity and becomes soft, and the printed image bleeds during storage and is clear. It is not preferable because an image cannot be obtained. Further, a color pigment, a white pigment, an extender pigment, a filler, an ultraviolet absorber, an antistatic agent, a heat stabilizer, an antioxidant, an optical brightening agent, etc. can be optionally used on the dye receiving surface. .

A magnetic recording layer, an embossed pattern, an optical memory, an IC memory, etc. may be formed on the card base material in advance.

(Others) As the means for applying the thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention and the transferred material as described above, any conventionally known applying means can be used. Printer (eg V
5-100 mJ by controlling the recording time with a recording device (DS510, CP510, etc.)
By applying thermal energy of about / mm ² ,
The object of the present invention can be sufficiently achieved.

[0023]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, “part” or “%” is based on weight unless otherwise specified. (Example 1 and Comparative Example 1) An ink for a heat resistant slipping layer having the following composition was dried on one surface of a 6 μm thick polyethylene terephthalate film (Lumirror Toray Co., Ltd.) when dried.
Apply using a gravure coater to achieve g / m ² ,
It was dried, provided with a heat resistant slipping layer, and further heat-aged at 60 ° C. for 5 days in an oven for curing treatment. Ink for heat-resistant slip layer Polyvinyl butyral resin (S-REC BX-1 Sekisui Chemical Co., Ltd.) 3.6 parts Polyisocyanate (Bernock D750 manufactured by Dainippon Ink) 8.4 parts Phosphate ester-based interfacial lubricant (PRYSURF A208S manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 2.8 parts Talc (Microace P-3 Nippon Talc) 0.6 parts Toluene / methyl ethyl ketone (1/1) 190 parts

Next, a dye layer composed of the following composition was applied to the surface opposite to the heat resistant slipping layer by a gravure coater,
After drying, a thermal transfer sheet R of Comparative Example 1 was obtained. Ink dye for dye layer formation (Kayaset Blue 714 (manufactured by Nippon Kayaku Co., Ltd.) 4.0 parts Polyvinyl acetoacetal resin (KS-5 Sekisui Chemical Co., Ltd.) 4.5 parts Polyethylene wax 0.1 part Toluene / methyl ethyl ketone (1/1 weight ratio) ) 91.5 parts Next, a thermal transfer sheet similar to the thermal transfer sheet R is prepared, and the following releasable film-forming ink is applied onto the dye layer by a miya bar so that the dry thickness is the following, and dried. A releasable film was formed to prepare thermal transfer sheets A to D of the examples of the present invention. Ink for forming releasable film Polyvinyl alcohol (Gosenol C-500, manufactured by Nippon Synthetic Chemical Industry) X part Nonionic interface Activator (Leodol TWO-120, manufactured by Kao) 0.15 parts Water / ethyl alcohol (9/1 (weight ratio) solution) 99.85-X parts

[0025]

[Table 1]

(Example 2) A thermal transfer sheet having a dye layer provided on a substrate was prepared in the same manner as in Example 1, and then a release film-forming ink having the following composition was used on the dye layer. Similarly, the thermal transfer sheets E to H of the present invention were prepared by applying and drying so as to have the following thickness when dried to form a releasable film. Ink for forming releasable film Polyvinyl acetoacetal (KW-1, manufactured by Sekisui Chemical Co., Ltd.) X part Molecular weight about 33,000 Water / ethyl alcohol (9/1 (weight ratio) solution 100-X part

[0027]

[Table 2]

(Example 3) In Example 1, the ink for forming the releasable film had the following composition and had a dry thickness of 10 ^-2 µm.
A thermal transfer sheet I was prepared in the same manner except that m was used. Ink for forming releasable film Hydroxypropyl cellulose 0.2 part (TCI-EP 10 to 4000 cps Tokyo Chemical Industry) Water / ethyl alcohol (9/1 (weight ratio) solution) 99.8 parts

(Receptor) The thermal transfer sheets of Examples and Comparative Examples of the present invention were used to print on a receptor made of vinyl chloride having the following composition, using a thermal printer for cards (manufactured by Card Printer CP510 / VDS). Then, the releasability and the print density were measured. The print density was measured near the maximum density using a Macbeth reflection density system RD-918. Material composition of card base material Polyvinyl chloride compound (polymerization degree 800) 100 parts (containing about 10% of additives such as stabilizers) White pigment (titanium oxide) 10 parts Plasticizer (DOP) 0.5 part

The measurement results of experiments conducted on each thermal transfer sheet are shown below.

[0031]

[Table 3]

[0032]

As in the present invention, a vinyl chloride resin is formed by forming a release film made of a water-soluble resin on the dye layer so that the dry coating amount is 10 ^{-3 to 1} μm. It is possible to obtain a thermal transfer sheet which is excellent in releasability from a receptor and does not cause set-off of dye even during storage by winding.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a cross section of a thermal transfer sheet of the present invention.

FIG. 2 is a diagram schematically showing an example of a receptor that is preferably used in the thermal transfer recording method of the present invention.

[Explanation of symbols]

 1: Base film 2: Dye layer 4: Releasable film 5: Thermal transfer sheet 6: Card 7: Center core 8,8 ': Polyvinyl chloride layer

Claims (17)

[Claims] 1. A releasable film having a thickness of 10 ⁻³ to 1 μm made of a water-soluble resin, which is provided with a dye layer containing a heat transferable dye and a binder on a substrate film. A thermal transfer sheet for forming an image on a receiver made of a vinyl chloride resin, which is formed of the above. 2. The thermal transfer sheet according to claim 1, wherein the release film made of the water-soluble resin is a continuous film. 3. The thermal transfer sheet according to claim 1, wherein the releasing film made of the water-soluble resin is a discontinuous film. 4. The thermal transfer sheet according to claim 1, wherein the release film and the dye layer binder are made of the same type of resin. 5. The thermal transfer sheet according to claim 1, wherein the water-soluble resin is formed of at least one of polyvinyl alcohol, polyvinyl acetal, and water-soluble cellulose resin. 6. The thermal transfer sheet according to claim 1, wherein the polyvinyl acetal has a polyvinyl alcohol content of 80% by weight or more and less than 100%. 7. The thermal transfer sheet according to claim 1, wherein the release film contains a surfactant. 8. The thermal transfer according to claim 1, wherein the content of the surfactant is 50 to 200 parts by weight based on the solid content of the water-soluble resin. Sheet. 9. A thickness of 10 ^-3 comprising a water-soluble resin and a dye layer containing a heat transferable dye and a binder on a base film.
An image is formed on the receptor by superimposing a thermal transfer sheet having a releasable film of ˜1 μm laminated on it and a receptor made of vinyl chloride resin and heating the dye according to image information to transfer the dye thermally. A thermal transfer recording method, which comprises: 10. A release film comprising the water-soluble resin,
The thermal transfer recording method according to claim 9, wherein the thermal transfer recording method comprises a continuous film. 11. A release film comprising the water-soluble resin,
10. The thermal transfer recording method according to claim 9, comprising a discontinuous film. 12. The thermal transfer recording method according to claim 9, wherein the water-soluble resin is formed of at least one of polyvinyl alcohol, polyvinyl acetal and water-soluble cellulose resin. 13. The thermal transfer recording method according to claim 9, wherein the polyvinyl acetal has a polyvinyl alcohol content of 80% by weight or more and less than 100%. 14. The thermal transfer recording method according to claim 9, wherein the film made of the water-soluble resin contains a surfactant. 15. The thermal transfer recording method according to claim 14, wherein the content of the surfactant is 50 to 200 parts by weight based on the solid content of the water-soluble resin. 16. The thermal transfer recording method according to claim 9, wherein the receptor is a card. 17. The thermal transfer recording method according to claim 9, wherein the receptor comprises a substrate on which a receptor layer made of vinyl chloride or a vinyl chloride-vinyl acetate copolymer resin is provided.