JP4061313B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet in which a heat-resistant slipping layer is provided on one surface of a substrate, and an adhesive layer and a dye layer are sequentially formed on the other surface of the substrate. The present invention relates to a thermal transfer sheet that can prevent abnormal transfer such that the entire dye layer is transferred during printing on a transfer body.

  Conventionally, various thermal transfer recording methods are known. Among them, a thermal transfer sheet having a dye layer in which a dye for sublimation transfer is used as a recording material and this is supported on a base material such as a polyester film with a suitable binder. From the above, there are proposed methods for forming various full-color images by thermally transferring a sublimation dye onto a transfer material that can be dyed with a sublimation dye, for example, a thermal transfer image-receiving sheet having a dye-receiving layer formed on paper or a plastic film. Yes. In this case, as the heating means, the color dots having a large number of three or four colors adjusted by heating with the thermal head of the printer are transferred to the receiving layer of the thermal transfer image receiving sheet, and the multicolored color dots are transferred. To reproduce the full color of the document. The image formed in this way is very clear and excellent in transparency because the coloring material used is a dye, so the resulting image is excellent in the reproducibility and gradation of intermediate colors, It is possible to form a high-quality image similar to an image obtained by offset printing or gravure printing and comparable to a full-color photographic image.

  In such a thermal transfer recording system using sublimation transfer, as the printing speed of the thermal transfer printer is increased, there has been a problem that a sufficient print density cannot be obtained with the conventional thermal transfer sheet. Also, there has been a demand for higher density and clearer prints of thermal transfer images, and improved thermal transfer image-receiving sheets that accept images of sublimation dyes transferred from the thermal transfer sheet and the thermal transfer sheet. Many attempts have been made. For example, attempts have been made to improve transfer sensitivity in printing by reducing the thickness of the thermal transfer sheet, but wrinkles may occur due to heat, pressure, etc. during manufacture of the thermal transfer sheet or during thermal transfer recording. Causes the problem of cutting.

  In addition, the dye / resin (Dye / Binder) ratio in the dye layer of the thermal transfer sheet was increased to try to improve the printing density and the transfer sensitivity in the printing. When the dye is transferred to the heat-resistant slipping layer of the material and the transferred dye is rolled back, it is re-transferred to the dye layer of another color (kickback), and the contaminated layer is thermally transferred to the image receiving sheet. The hue may be different from that of the original color, or the so-called background stain may occur. In the thermal transfer printer, not on the thermal transfer sheet side, high energy was applied during thermal transfer during image formation. However, the dye layer and the receiving layer are fused, and so-called abnormal transfer is likely to occur. When a large amount of a release agent is added to the receiving layer to prevent the abnormal transfer, blurring of the image, background smearing, etc. occur.

  In addition, as a prior art, Patent Document 1 discloses a thermal transfer in which a hydrophilic barrier / undercoat layer using polyvinyl pyrrolidone as a main component and polyvinyl alcohol as a component for improving dye transfer efficiency is provided between a dye layer and a support. A sheet is disclosed. This polyvinyl pyrrolidone is for preventing abnormal transfer and preventing adhesion at the time of printing.Polyvinyl alcohol has a function of improving transfer sensitivity, and that polyvinyl pyrrolidone improves transfer sensitivity. There is no description.

  In addition, the present applicant describes in Patent Document 2 that the use of a dye layer primer layer containing polyvinyl pyrrolidone has the effect of increasing the sensitivity in thermal transfer and abnormal transfer. Depending on the properties, the adhesion of the primer layer decreases, especially under high temperature and high humidity, and the dye layer is taken together with the receiving layer of the image receiving sheet during thermal transfer, or because the primer layer and the dye layer are mixed. There arises a problem that the receiving layer is taken together with the possible dye layer.

As described above, thermal transfer recording materials for thermal transfer sheets and thermal transfer image-receiving sheets that can be adjusted and used on the thermal transfer printer side in response to higher printing speeds of thermal transfer and higher density and quality requirements of thermal transfer images However, in this situation, a sufficient print density cannot be obtained, abnormal transfer occurs during thermal transfer, other problems occur, and a sufficiently high quality print cannot be obtained.
Japanese Examined Patent Publication No. 7-102746 Japanese Patent Application No. 14-181812

  Therefore, in order to solve the above-described problems, the present invention responds to the demand for higher printing speed of thermal transfer, higher density and higher quality of thermal transfer images, improved transfer sensitivity in printing, higher temperature and higher temperature. It is an object of the present invention to provide a thermal transfer sheet that prevents the occurrence of abnormal transfer, wrinkles and the like even under an environment such as in a humidity.

The invention according to claim 1 is a thermal transfer sheet in which a heat-resistant slipping layer is provided on one surface of a substrate, and an adhesive layer and a dye layer are sequentially formed on the other surface of the substrate. As a resin and a complex-forming agent, any one of hydrolyzable tannic acid or pyrogallol derivative is contained, and the complex-forming agent is contained at a ratio of 0.5% to 10% with respect to the total solid content of the adhesive layer It is characterized by that.

The invention of claim ² is characterized in that the adhesive layer according to claim 1 has a coating amount of 0.05 to 0.3 g / m ² at the time of drying.

The present invention relates to a thermal transfer sheet in which a heat-resistant slipping layer is provided on one surface of a base material, and an adhesive layer and a dye layer are sequentially formed on the other surface of the base material. The adhesive layer includes a polyvinylpyrrolidone resin and a complex-forming agent. As any one of hydrolyzable tannic acid and pyrogallol derivative and the complex-forming agent is contained at a ratio of 0.5% to 10% with respect to the total solid content of the adhesive layer. The polyvinyl pyrrolidone resin and the complex-forming agent are combined to form a polyvinyl pyrrolidone complex (complex) so that the polyvinyl pyrrolidone resin does not absorb moisture and the adhesion to the base material decreases. Is not soluble in water and has no hygroscopicity. Therefore, as a result, the polyvinyl pyrrolidone resin and its complex are mixed in the adhesive layer, so that the adhesion between the dye layer and the substrate can be improved even under an environment such as high temperature and high humidity, and abnormal transfer and the like are prevented. did it. In addition, transfer sensitivity is greatly improved during thermal transfer, and a high-density thermal transfer image can be obtained without applying high energy.

  FIG. 1 shows one embodiment of the thermal transfer sheet of the present invention, and a heat-resistant slipping layer 4 is provided on one surface of a substrate 1 to improve the slipperiness of the thermal head and prevent sticking. In this structure, a linear polymer polyvinylpyrrolidone resin and a complexing agent are mixed and formed on the other surface of the substrate 1 in this order. However, the complex-forming agent contained in the adhesive layer is contained in a proportion of 0.5% to 10% with respect to the total solid content of the adhesive layer.

Hereinafter, each layer constituting the thermal transfer sheet of the present invention will be described in detail.
(Base material)
The base material 1 of the thermal transfer sheet used in the present invention may be any material as long as it has a conventionally known degree of heat resistance and strength. For example, it has a thickness of about 0.5 to 50 μm, preferably about 1 to 10 μm. Polyethylene terephthalate film, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, acetic acid Examples thereof include cellulose derivatives such as cellulose, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film, and the like.

  In the above-mentioned base material, it is common to perform an adhesion treatment on the surface on which the adhesive layer and the dye layer are formed. When the plastic film of the base material is formed by applying an adhesive layer thereon, the wettability, adhesiveness, etc. of the coating solution are likely to be insufficient, and therefore, an adhesive treatment is performed. As the adhesion treatment, known resin surface modification such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, primer treatment, grafting treatment, etc. Quality technology can be applied as it is. Two or more of these treatments can be used in combination. The primer treatment can be performed, for example, by applying a primer solution to an unstretched film at the time of film formation by melt extrusion of a plastic film and then stretching the film.

  Furthermore, it is also possible to apply and form a primer layer between the base material and the adhesive layer as the above-mentioned base material adhesion treatment. The primer layer can be formed from a resin as shown below. Polyester resin, Polyacrylate resin, Polyvinyl acetate resin, Polyurethane resin, Styrene acrylate resin, Polyacrylamide resin, Polyamide resin, Polyether resin, Polystyrene resin, Polyethylene resin, Polypropylene Examples thereof include resins, vinyl resins such as polyvinyl chloride resins and polyvinyl alcohol resins, and polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral. However, in the thermal transfer sheet in which the adhesive layer and the dye layer are sequentially formed on the base material of the present invention, the adhesive property of the adhesive layer to the base material is sufficiently high. It is possible to directly provide an adhesive layer.

(Adhesive layer)
The adhesive layer 2 provided between the base material and the dye layer in the thermal transfer sheet of the present invention contains a polyvinyl pyrrolidone resin and a complex forming agent. Examples of the polyvinylpyrrolidone resin include homopolymers of vinylpyrrolidone such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, and copolymers thereof. In particular, a linear polymer polyvinyl pyrrolidone resin is preferably used because it is highly effective in improving the transfer sensitivity in printing and has adhesion between the dye layer and the substrate. As the polyvinyl pyrrolidone resin, those having a K value in the Fickencher formula of 60 or more are preferably used, and in particular, grades of K-60 to K-120 can be used, and the number average molecular weight is 30,000 to 280, About 000. When the polyvinyl pyrrolidone resin having a K value of less than 60 is used, the effect of improving transfer sensitivity in printing is reduced.

  Further, as the polyvinylpyrrolidone resin, not only the above-mentioned N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone monomers, but also N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N- It may be a polymer containing a derivative having a substituent on the pyrrolidone ring, such as vinyl-3,3,5-trimethylpyrrolidone, N-vinyl-3-benzylpyrrolidone. In addition to the polyvinyl pyrrolidone resin, a polyvinyl alcohol resin, a cellulose derivative, or the like can be mixed and used as the binder resin for the adhesive layer.

  The complex forming agent contained in the adhesive layer will be described below. The complex-forming agent is added as a molecule to the end of polyvinylpyrrolidone to form a complex, and the resulting complex has lost the water absorption property of the polyvinylpyrrolidone resin, that is, a substance that is insoluble in water. It becomes. Examples of the complex forming agent include polyacrylic acid, tannic acid, and phenols such as resorcin and pyrogallol.

  The above tannic acid is usually tannin obtained from a quintuplet or a gallic litter. Tannins are divided into two groups: hydrolyzed tannins and condensed tannins. Hydrolyzed tannins are a group of pyrogallol tannins that are decomposed into alcohol (usually glucose) and acid (usually gallic acid) by acid, alkali or enzyme (tannase). Typical examples are pentaploid tannin and gallic tannin. In the present invention, hydrolyzed tannin is preferably used. In addition to pyrogallol, pyrogallol derivatives such as pyrogallol ether, pyrogallol ester, and gallic acid ester can be used as the above-mentioned pyrogallol.

  In the present invention, hydrolyzable tannins and pyrogallol derivatives are particularly preferably used among the complex forming agents described above, and good adhesion can be obtained at both room temperature and high humidity in the adhesion between the substrate and the dye layer. It is done. In the present invention, in order to prevent the polyvinyl pyrrolidone resin from absorbing moisture in the adhesive layer and deteriorating the adhesion to the substrate, the polyvinyl pyrrolidone resin and the complex forming agent are combined to form polyvinyl pyrrolidone. The complex is not soluble in water and does not have hygroscopicity. Therefore, as a result, the polyvinyl pyrrolidone resin and its complex are mixed in the adhesive layer, so that the adhesion between the dye layer and the substrate can be improved even under an environment such as high temperature and high humidity, and abnormal transfer and the like are prevented. did it. Two or more of the above complex forming agents may be used in combination as long as there is no influence of interaction.

  The above complex-forming agent is contained at a ratio of 0.5% to 10% with respect to the total solid content of the adhesive layer. The adhesion between the dye layer and the substrate is improved. When the content ratio of the complex-forming agent is less than the above range, the adhesion between the dye layer and the substrate under high temperature and high humidity is lowered, and abnormal transfer or the like is likely to occur. On the other hand, when the content ratio of the complex-forming agent is larger than the above range, the adhesion between the dye layer and the substrate at room temperature or the like is lowered.

The adhesive layer is a coating solution prepared by mixing the above complex forming agent and polyvinylpyrrolidone resin, and adding or adding additives as necessary, in water or an aqueous solvent or an organic solvent such as alcohols. It can be adjusted and formed using a known coating means such as a gravure printing method, a screen printing method, or a reverse roll coating method using a gravure plate. The adhesive layer thus formed preferably has a coating amount in the range of 0.05 to 0.3 g / m ² when dried. If the coating amount is small, the unevenness of the base material cannot be filled, and an uncoated part is generated, and this part becomes a trigger, and abnormal transfer occurs in which the dye layer is taken on the receiving layer side of the image receiving sheet during thermal transfer. Cheap. On the other hand, when the coating amount of the adhesive layer is larger than the above range, the adhesive layer and the dye layer are easily mixed during the dye layer coating, and the receiving layer is easily taken on the dye layer side during the thermal transfer.

(Dye layer)
In the thermal transfer sheet of the present invention, the dye layer 3 is provided on the other surface of the base material provided with a heat-resistant slipping layer on one surface via an adhesive layer. The dye layer may be composed of a single layer of one color, or a plurality of dye layers containing dyes having different hues may be repeatedly formed on the same surface of the same substrate in the surface order. The dye layer is a layer formed by supporting a heat transfer dye with an arbitrary binder. As the dye to be used, a dye that melts, diffuses or sublimates by heat, and is used in a conventionally known sublimation transfer type thermal transfer sheet can be used in the present invention. The selection is made in consideration of printing sensitivity, light resistance, storage stability, solubility in a binder, and the like.

  Examples of the dye include azomethines such as diarylmethane, triarylmethane, thiazole, merocyanine, pyrazolone methine and the like, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazolazomethine, imidazoazomethine, and pyridone azomethine. , Xanthene, oxazine, dicyanostyrene, cyanomethylene represented by tricyanostyrene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrroleazo, pyralazo, imidazoleazo, Azos such as thiadiazole azo, triazole azo, dizazo, spiropyran, indolinospiropyran, fluoran, rhodamine lactam, naphthoquinone, anne Rakinon system include the quinophthalone like.

  As the binder for the dye layer, any conventionally known resin binder can be used. Examples of preferred binders include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and butyric acid cellulose. , Polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polyacrylamide and other vinyl resins, polyester resins and phenoxy resins. Among these, cellulose resins, acetal resins, butyral resins, polyester resins, phenoxy resins, and the like are particularly preferable from the viewpoints of heat resistance, dye migration, and the like.

  In the present invention, the following releasable graft copolymer can be used as a release agent or binder in place of the resin binder. This releasable graft copolymer is obtained by graft polymerizing at least one releasable segment selected from a polysiloxane segment, a fluorocarbon segment, a fluorinated hydrocarbon segment, or a long-chain alkyl segment on a polymer main chain. Is. Among these, a graft copolymer obtained by grafting a polysiloxane segment to a main chain made of a polyvinyl acetal resin is particularly preferable.

The dye layer may contain the above-mentioned dyes, binders, and other various conventional additives as required. Examples of the additive include organic fine particles such as polyethylene wax and inorganic fine particles in order to improve releasability from the image receiving sheet and ink coating suitability. Such a dye layer is usually prepared by adding the above-mentioned dye, binder, and additives as necessary in an appropriate solvent, and dissolving or dispersing each component to prepare a coating solution. It can be formed by applying and drying the liquid on a substrate. As this coating method, known means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, or the like can be used. The dye layer thus formed has a coating amount at the time of drying of about 0.2 to 6.0 g / m ² , preferably about 0.3 to 3.0 g / m ² .

(Heat resistant slipping layer)
In the thermal transfer sheet of the present invention, a heat-resistant slipping layer 4 is provided on one surface of the substrate in order to prevent adverse effects such as sticking and printing wrinkles due to the heat of the thermal head. The resin for forming the thermal slipping layer may be any conventionally known resin, for example, polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, Polybutadiene resin, styrene-butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetate propionate resin, cellulose Acetate butyrate resin, cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, poly Boneto resins, and chlorinated polyolefin resins.

  The slipperiness imparting agent added to or overcoating the heat resistant slipping layer made of these resins includes phosphate ester, silicone oil, graphite powder, silicone graft polymer, fluorine graft polymer, acrylic silicone graft polymer, acrylic siloxane, aryl Examples thereof include silicone polymers such as siloxane, but a layer made of a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound, and a phosphate ester compound, and it is more preferable to add a filler.

The heat-resistant slipping layer is prepared by dissolving or dispersing the above-described resin, slipperiness-imparting agent, and filler in an appropriate solvent on the base sheet to prepare a heat-resistant slipping layer coating solution. This can be formed by coating with a forming means such as gravure printing, screen printing, reverse roll coating using a gravure plate, and drying. The coating amount of the heat-resistant slip layer is a ^{solid, 0.1g / m 2 ~3.0g / m} 2 is preferred.

Next, an Example and a comparative example are given and this invention is explained in full detail. In the text, “part” or “%” is based on mass unless otherwise specified. The adhesive layer coating solution having the following composition is dried on the untreated polyethylene terephthalate film (PET) (Mitsubishi Chemical Polyester Film Co., Ltd., Diafoil K880) having a thickness of 4.5 μm by gravure coating. It apply | coated so that an application quantity might be 0.06 g / m < ² >, and it dried at 110 degreeC for 1 minute, and formed the contact bonding layer.

Further, on the adhesive layer, a dye layer coating solution having the following composition was applied by gravure coating so that the dry coating amount was 0.8 g / m ² and dried to form a dye layer. A thermal transfer sheet is prepared. In addition, a heat resistant slipping layer coating solution having the following composition is applied to the other surface of the base material in advance by gravure coating and dried so that the dry coating amount becomes 1.0 g / m ² . A layer was formed.

<Adhesive layer composition A>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.9 parts Hydrolyzed tannic acid (Dainippon Pharmaceutical Co., Ltd., special tannic acid) 0.1 part Water 83 parts Isopropyl alcohol 83 parts

<Dye layer composition liquid 1>
C. I. Solvent Blue 22 5.5 parts Polyvinyl acetal resin 3.0 parts (SREC KS-5 Sekisui Chemical Co., Ltd.)
Methyl ethyl ketone 22.5 parts Toluene 68.2 parts

<Heat resistant slipping layer composition>
13.6 parts of polyvinyl butyral resin (manufactured by SREC BX-1 by Sekisui Chemical Co., Ltd.)
0.6 parts of polyisocyanate curing agent (Takenate D218, Takeda Pharmaceutical Company Limited)
Phosphate 0.8 parts (Plysurf A208S, Daiichi Kogyo Seiyaku Co., Ltd.)
Methyl ethyl ketone 42.5 parts Toluene 42.5 parts

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 2.

<Adhesive layer composition B>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.5 parts Hydrolyzed tannic acid (Dainippon Pharmaceutical Co., Ltd., special tannic acid) 0.5 part Water 83 parts Isopropyl alcohol 83 parts

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 3.

<Adhesive layer composition C>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.0 parts Hydrolyzed tannic acid (Dainippon Pharmaceutical Co., Ltd., special tannic acid) 1.0 part Water 83 parts Isopropyl alcohol 83 parts

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 4.

<Adhesive layer composition liquid D>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.9 parts Pyrogallol derivative (Dainippon Pharmaceutical Co., Ltd., trade name Pyrogallol N) 0.1 part Water 83 parts Isopropyl alcohol 83 parts

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat resistant slipping layer is provided by gravure coating and dried to a dry coating amount of 0.05 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 5.

<Adhesive layer composition liquid E>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.5 parts Pyrogallol derivative (Dainippon Pharmaceutical Co., Ltd., trade name Pyrogallol N) 0.5 parts Water 83 parts Isopropyl alcohol 83 parts

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. The adhesive layer coating solution used in Example 5 was applied to the surface of the base material opposite to the surface on which the heat-resistant slip layer was provided by gravure coating so that the dry coating amount was 0.1 g / m ^2. And dried to form an adhesive layer. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 6.

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. The adhesive layer coating solution used in Example 5 was applied to the surface opposite to the surface on which the heat-resistant slip layer of the substrate was provided, by gravure coating so that the dry coating amount was 0.2 g / m ^2. And dried to form an adhesive layer. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 7.

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. The adhesive layer coating solution used in Example 5 was applied by gravure coating on the surface opposite to the surface on which the heat-resistant slipping layer of the substrate was provided so that the dry coating amount was 0.25 g / m ^2. And dried to form an adhesive layer. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 8.

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. The adhesive layer coating solution used in Example 5 was applied to the surface opposite to the surface on which the heat-resistant slipping layer of the substrate was provided by gravure coating so that the dry coating amount was 0.03 g / m ^2. And dried to form an adhesive layer. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce a thermal transfer sheet of Example 9.

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. The adhesive layer coating solution used in Example 5 was applied to the surface opposite to the surface on which the heat-resistant slipping layer of the substrate was provided by gravure coating so that the dry coating amount was 0.35 g / m ^2. And dried to form an adhesive layer. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 10.

A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce the thermal transfer sheet of Example 11.

<Adhesive layer composition liquid F>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 9.0 parts Pyrogallol derivative (trade name Pyrogallol N, manufactured by Dainippon Pharmaceutical Co., Ltd.) 1.0 part Water 83 parts Isopropyl alcohol 83 parts

(Comparative Example 1)
A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce a thermal transfer sheet of Comparative Example 1.

<Adhesive layer composition liquid G>
Polyvinyl pyrrolidone resin (K-90, manufactured by ISP Ltd.) 10 parts Water 83 parts Isopropyl alcohol 83 parts

(Comparative Example 2)
A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce a thermal transfer sheet of Comparative Example 2.

<Adhesive layer composition liquid H>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 8.0 parts Hydrolyzed tannic acid (Dainippon Pharmaceutical Co., Ltd., special tannic acid) 2.0 parts Water 83 parts Isopropyl alcohol 83 parts

(Comparative Example 3)
A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. An adhesive layer coating solution having the following composition is applied to the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided by gravure coating and dried to a dry coating amount of 0.06 g / m ^2. Thus, an adhesive layer was formed. Further, a dye layer is formed on the adhesive layer in the same manner as in Example 1 to produce a thermal transfer sheet of Comparative Example 3.

<Adhesive layer composition liquid I>
Polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.) 8.0 parts Pyrogallol derivative (Dainippon Pharmaceutical Co., Ltd., trade name Pyrogallol N) 2.0 parts Water 83 parts Isopropyl alcohol 83 parts

(Comparative Example 4)
A PET film substrate having the same conditions as in Example 1 was used, and a heat-resistant slipping layer similar to that in Example 1 was previously formed on the other surface of the substrate. A dye layer is directly formed in the same manner as in Example 1 without providing an adhesive layer on the surface of the substrate opposite to the surface on which the heat-resistant slip layer is provided, and a thermal transfer sheet of Comparative Example 4 is produced.

  Using the thermal transfer sheets of Examples and Comparative Examples prepared above, each evaluation of heat-resistant adhesion at room temperature and high temperature and high humidity and adhesion to an image receiving sheet was performed by the following methods.

(Heat resistant adhesiveness 1)
A thermal transfer sheet as a sample of Examples and Comparative Examples is pasted on a mount with the dye layer side facing up (the mount and the heat-resistant slipping layer are in contact with each other). And the reference ribbon 1 corresponding to the sample (the condition of the dye layer is the same, the base material is made by Mitsubishi Chemical Polyester Film Co., Ltd., and the dye layer is provided directly on the easy-foil-treated PET film of Diafoil K230E) Attached to different positions on the same mount with the dye layer surface facing up, the sample and the reference ribbon are folded back so that the dye layer surfaces are in contact with each other, temperature 100 to 130 ° C., pressure 34.3 × 10 Heat sealing was performed at ⁴ Pa and a pressurization time of 2 seconds, both were peeled off, and the remaining state (taken state) of each dye layer of the sample and the reference ribbon 1 was visually examined, and evaluated according to the following criteria. did. However, both the thermal transfer sheet and the reference ribbon 1 as the samples of the examples and comparative examples are subjected to the heat sealing in a state of being left at room temperature, and both the thermal transfer sheet and the reference ribbon 1 as the samples are 40 ° C. After standing in a 90% RH environment for 16 hours, the above-described heat sealing was conducted in two ways.

○: The area of the dye layer remaining on the sample side is larger than the area remaining on the reference ribbon side.
Δ: The area of the dye layer remaining on the sample side is equal to the area remaining on the reference ribbon side.
X: The area of the dye layer remaining on the sample side is smaller than the area remaining on the reference ribbon side.

(Heat resistant adhesion 2)
A thermal transfer sheet as a sample of Examples and Comparative Examples is pasted on a mount with the dye layer side facing up (the mount and the heat-resistant slipping layer are in contact with each other). Then, the reference ribbon 2 corresponding to the sample (the conditions of the dye layer are the same, the base material is a polyvinyl pyrrolidone resin (K-90, ISP) on the surface of a PET film of Diafoil K880 manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. Ltd.) (adhesive layer equivalent to the adhesive layer condition of Comparative Example 1 provided to be 0.06 g / m ² when dried) with the dye layer side up and different positions on the same mount Wrapping each sheet so that the sample and the dye layer surface of the reference ribbon are in contact with each other, and heat-sealing is performed at a temperature of 100 to 130 ° C., a pressure of 34.3 × 10 ⁴ Pa, and a pressurization time of 2 seconds. Both were peeled off, and the remaining state (taken state) of each dye layer of the sample and the reference ribbon 2 was visually examined and evaluated according to the same standard as the heat resistant adhesiveness 1 described above. However, both the thermal transfer sheet and the reference ribbon 2 as the samples of the example and the comparative example are subjected to the heat seal in a state of being left at room temperature, and both the thermal transfer sheet and the reference ribbon 2 as the samples are 40 ° C. After standing in a 90% RH environment for 16 hours, the above-described heat sealing was conducted in two ways.

(Adhesiveness with image receiving sheet)
The dye layer surface of each of the thermal transfer sheets obtained in the above Examples and Comparative Examples was superposed so that the image receiving surface of the image receiving sheet of Olympus Corporation's digital color printer P-200 dedicated standard set was in contact, and the temperature was 100 ~ 130 ° C, pressure 34.3 × 10 ⁴ Pa, pressurization time 2 sec, heat seal, peel both, and visually check the peeled state of the dye layer of the sample and the image receiving layer of the image receiving sheet. Evaluation was made based on the criteria. In this case, the heat transfer sheet and the image receiving sheet were left to stand at room temperature, and the heat sealing was performed.

○: The image receiving layer is not peeled off on the dye layer side, and there is no abnormality.
X: The image receiving layer is peeled off on the dye layer side.

＊１；錯体形成剤の添加量は、ポリビニルピロリドン樹脂（Ｋ−９０、ＩＳＰ Ｌｔｄ．製）と合わせた全体に対する添加量の割合である。但し、固形分基準での割合である。 The evaluation results of the above examples and comparative examples are shown in Table 1 below.

* 1: The addition amount of the complex forming agent is a ratio of the addition amount to the whole combined with the polyvinylpyrrolidone resin (K-90, manufactured by ISP Ltd.). However, the ratio is based on solid content.

From the above results, pyrogallol derivative, which is a complex-forming agent, is contained in the adhesive layer in a proportion of 5% with respect to the total solid content of the adhesive layer, and the coating amount of the adhesive layer is 0.1 to 0.25 g in a dry state. In Examples 6, 7, and 8 that are / m ² , good results were obtained with respect to all of the heat-resistant adhesiveness 1 and 2 and the adhesiveness to the image receiving sheet. In Examples 1 to 5 and Example 11, hydrolyzable tannic acid or pyrogallol derivative, which is a complex-forming agent, is contained in the adhesive layer in a proportion of 0.5% to 10% with respect to the total solid content of the adhesive layer. The coating amount of the adhesive layer is 0.05 to 0.06 g / m ² in a dry state, but the adhesive property is the same as that of the reference ribbon at room temperature of heat resistant adhesiveness 2, but it is the standard at high temperature and high humidity. The adhesion between the substrate and the dye layer was higher than that of the ribbon. Example 9 contains 5% of the complex-forming agent in the adhesive layer with respect to the total solid content of the adhesive layer, but the coating amount of the adhesive layer is 0.03 g / m ² in a dry state, The coating amount is too small, and the adhesion between the dye layer and the substrate under high temperature and high humidity is reduced. In Example 10, the complexing agent is contained in the adhesive layer in a proportion of 5% with respect to the total solid content of the adhesive layer, but the coating amount of the adhesive layer is 0.35 g / m ² in a dry state, The amount of coating was too large, indicating that the receptor layer was easily taken on the dye layer side during thermal transfer, which seems to be because the adhesive layer and the dye layer were easily mixed when the dye layer was applied.

  In Comparative Example 1, the adhesive layer did not contain any complex-forming agent, and it was found that, in the heat resistant adhesiveness 1, the adhesiveness between the dye layer and the substrate under high temperature and high humidity was lowered. In Comparative Examples 2 and 3, the complexing agent is contained in the adhesive layer in a proportion of 20% based on the total solid content of the adhesive layer, the content of the complexing agent is too large, and the linear polymer polyvinylpyrrolidone resin Since the ratio is small, the adhesiveness is lower than that of the reference ribbon at room temperature of heat resistant adhesiveness 2. In Comparative Example 4, a dye layer was directly provided on the base material without providing an adhesive layer. In heat-resistant adhesion, the dye layer and the base material at normal temperature and high temperature and high humidity were used. Adhesion is reduced.

It is a schematic sectional drawing which shows one embodiment which is the thermal transfer sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Adhesive layer 3 Dye layer 4 Heat resistant slipping layer

Claims (2)

In a thermal transfer sheet in which a heat-resistant slipping layer is provided on one side of the substrate and an adhesive layer and a dye layer are sequentially formed on the other side of the substrate, the adhesive layer is hydrolyzed as a polyvinylpyrrolidone resin and a complex-forming agent. Thermal transfer characterized in that it contains any one of a type tannic acid and a pyrogallol derivative and the complex-forming agent is contained in a proportion of 0.5% to 10% with respect to the total solid content of the adhesive layer Sheet. The thermal transfer sheet according to claim 1, wherein the adhesive layer has a coating amount of 0.05 to 0.3 g / m ² when dried.

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