JP4373253B2 - 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 base material, and an adhesive layer and a dye layer are sequentially formed on the other surface of the base material. The present invention relates to a thermal transfer sheet capable of obtaining a high-density print.

  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 ink 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. In Patent Document 2, there is provided a thermal transfer sheet in which an intermediate layer containing a sublimation dye having a diffusion coefficient smaller than that of the sublimation dye contained in the recording layer is provided between the base film and the recording layer containing the sublimation dye. Are listed. Only the use of hydroxyethyl cellulose is described as the contents of this intermediate layer. In any of the thermal transfer sheets disclosed in Patent Documents 1 and 2, the printed matter using the thermal transfer sheet has not yet reached a sufficient level as the maximum density.

Japanese Examined Patent Publication No. 7-102746 Japanese Patent Publication No. 5-69718

  Therefore, in order to solve the above-described problems, an object of the present invention is to provide a thermal transfer sheet that meets the demand for high density and high quality of thermal transfer images and has improved transfer sensitivity in printing.

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. And a water-soluble curing agent , and the water-soluble resin is a water-soluble nylon resin or an allylamine resin . The invention according to claim 2 is characterized in that the substrate according to claim 1 is subjected to corona treatment on the surface, and an adhesive layer is provided on the corona treatment surface.

The invention of claim 3 is characterized in that the water-soluble curing agent according to claim 1 is an epoxy curing agent or a carbodiimide curing agent. The invention of claim 4 is characterized in that the adhesive layer of claim 1 has a coating amount of 0.01 to 0.3 g / m ² when dried.

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, and the water-soluble resin containing active hydrogen in the adhesive layer And a water-soluble curing agent , and the water-soluble resin is a water-soluble nylon resin or an allylamine-based resin, and therefore, upon application and drying of the adhesive layer, by a curing reaction between the active hydrogen and the curing agent, The adhesive layer is cured, and the adhesion between the substrate and the dye layer becomes high. In addition, since the adhesive layer is formed of a thin film, the thermal transfer sheet and the image receiving sheet are overlapped, and the sublimation dye effectively shifts from the dye layer to the image receiving sheet side by heating from the back side of the thermal transfer sheet, Transfer sensitivity in printing is high, and particularly high-density printing can be obtained. In addition, since the adhesive layer is cured and has heat resistance, the print screen of the image receiving sheet is not matted by the heat when the thermal head is heated, and an excellent print quality is obtained.

  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 configuration, a water-soluble resin containing active hydrogen and an adhesive layer 2 containing a water-soluble curing agent and a dye layer 3 are sequentially formed on the other surface of the substrate 1.

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. The thermal transfer sheet of the present invention is provided with a dye layer on the base material via an adhesive layer, and in order to increase the adhesion between the base material and the adhesive layer, among the above-mentioned adhesive treatment, the cost is not high, A corona treatment that is readily available is preferred.

(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 water-soluble resin containing active hydrogen and a water-soluble curing agent. The active hydrogen-containing water-soluble resin includes glycols such as polyethylene glycol and polypropylene glycol, polyols such as polyester polyols, polyether polyols and acrylic polyols, polyurethane resin emulsions and dispersions, carboxylated styrene Aqueous emulsion / aqueous latex such as butadiene latex, acrylic acid-acrylic ester copolymer emulsion, urea-formaldehyde resin, melamine-formaldehyde resin, water-soluble nylon resin, allylamine resin, polyamide polyamine epichlorohydrin resin, etc. There are resins and the like, and these can be used alone or in combination of two or more.

  An adhesive layer using the above water-soluble nylon resin or allylamine resin is preferably used because it has high adhesion between the substrate and the dye layer. Specific examples of the water-soluble nylon resin include modified polyamide imparted with solubility in water and alcohol. From the viewpoint of the solution viscosity and the water resistance of the treated film, those having a mass average molecular weight of 2000 to 110,000 are preferably used.

  The allylamine resin of the water-soluble resin containing active hydrogen is polyallylamine or a copolymer thereof, and specific examples include polyallylamine and its inorganic acid salt, a copolymer of monoallylamine and diallylamine, and the like. Can do. Moreover, from the viscosity of a solution and the water resistance of the film | membrane after a process, a thing with a mass mean molecular weight of 9000-110,000 is preferable.

  The water-soluble resin containing the active hydrogen is cured by a curing reaction between the active hydrogen and the water-soluble curing agent. Examples of the water-soluble curing agent used in the adhesive layer include a water-soluble epoxy curing agent, a carbodiimide curing agent, an aziridine curing agent, and a hydrazine curing agent. In addition, so-called blocked isocyanate, in which the isocyanate group is once reacted and blocked with a blocking agent such as phenol, caprolactam, β-dicarbonyl compound, alcohol, oxime, or triazole, can be used. The blocking agent is dissociated and the original isocyanate becomes active.

  Among the above water-soluble curing agents, an epoxy curing agent or a carbodiimide-based curing agent has high suitability for curing a water-soluble resin containing active hydrogen with a water-soluble nylon resin or an allylamine resin, and is preferably used. Examples of the water-soluble epoxy curing agent include polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcin diglycidyl ether, sorbitol polyglycidyl ether, sorbitan poly Examples thereof include glycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like.

Examples of the water-soluble carbodiimide-based curing agent of the general formula _{R 1 -N = C = N-} R 2 ( wherein, R _1, R ₂ is a hydrogen atom, a propyl group, a cyclohexyl group or a p- toluoyl And the like, and this compound has been modified into a form imparted with hydrophilicity.

  The blending ratio of the water-soluble resin containing the active hydrogen and the water-soluble curing agent may be an amount necessary for curing the water-soluble resin containing the active hydrogen, as long as the quality of the adhesive layer is not impaired. It can be selected as appropriate. For example, the water-soluble curing agent is blended in an amount of about 5 to 500 parts by mass with respect to 100 parts by mass of the water-soluble resin containing active hydrogen. Since the adhesive layer of the present invention contains a water-soluble resin containing an active hydrogen and a water-soluble curing agent in the coating liquid, at the time of coating and drying the adhesive layer, by the curing reaction between the active hydrogen and the curing agent, The adhesive layer is cured, and the adhesion between the substrate and the dye layer becomes high.

  The adhesive layer adjusts a coating solution in which a water-soluble resin containing active hydrogen and a water-soluble curing agent are dissolved or dispersed in water or an aqueous solvent such as alcohol. In other words, since the adhesive layer coating liquid is an aqueous coating liquid, when the adhesive layer is applied and dried, and then the dye layer adjusted with the solvent-based coating liquid is applied and formed, the adhesive layer becomes a dye. Since they are mixed with each other and are not compatible with each other, the functions of the adhesive layer and the dye layer can be sufficiently exhibited. In addition, since the adhesive layer is formed as a thin film, the thermal transfer sheet and the image receiving sheet are overlapped, and the sublimation dye is effectively transferred from the dye layer to the image receiving sheet side by heating from the back side of the thermal transfer sheet to the image receiving sheet. Transfer sensitivity is high, and particularly high density prints can be obtained. In addition, since the adhesive layer is cured and has heat resistance, the print screen of the image receiving sheet is not matted by the heat when the thermal head is heated, and an excellent print quality is obtained.

The adhesive layer is a coating in which the water-soluble resin containing active hydrogen listed above and a water-soluble curing agent are mixed and an additive is added as necessary, dissolved or dispersed in water or an aqueous solvent such as alcohol. It can be 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 by adjusting the working liquid. Adhesive layer thus formed is coated amount after drying is in a range of 0.01 to 0.3 g / m ^2, in particular in the range of 0.05 to 0.1 / m ² is preferred. 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 transfer sensitivity in printing is lowered.

(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. The liquid can be formed on a substrate by applying and drying. 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, and 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 slip 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 slip layer coating solution. This can be formed by applying and drying by a forming means such as a gravure printing method, a screen printing method, or a reverse roll coating method using a gravure plate. 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 further explained in full detail. In the text, “part” or “%” is based on mass unless otherwise specified. On the base material, a corona-treated polyethylene terephthalate film (PET) having a thickness of 5.0 μm (5AF56, manufactured by Toray Industries, Inc.), an adhesive layer coating solution having the following composition is applied by gravure coating, so that the dry coating amount is It apply | coated so that it might become 0.08 g / m < ² >, and it dried at 110 degreeC for 1 minute, and formed the contact bonding layer.

Furthermore, 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>
100 parts of water-soluble nylon resin (aqueous amide resin) (trade name Toresin FS350 E5AS, a 30% aqueous solution of methoxymethylated nylon, manufactured by Nagase ChemteX Corporation)
5 parts of water-soluble epoxy curing agent (trade name DECONAR EX-313, manufactured by Nagase ChemteX Corporation)
500 parts of water 500 parts of isopropyl alcohol

<Dye layer composition liquid 1>
C. I. Solvent Blue 63 5.5 parts Polyvinyl acetal resin 3.0 parts (S-REC 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 0.08 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>
100 parts of water-soluble methoxycarbonylallylamine resin (trade name “PAA-H10C”, manufactured by Nisshinbo Co., Ltd.)
30 parts of water-soluble carbodilite curing agent (trade name “V02”, manufactured by Nisshinbo Co., Ltd.)
500 parts of water 500 parts of isopropyl alcohol

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 0.08 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>
100 parts of water-soluble methoxycarbonylallylamine resin (trade name “PAA-H10C”, manufactured by Nisshinbo Co., Ltd.)
5 parts of water-soluble epoxy curing agent (trade name DECONAR EX-313, manufactured by Nagase ChemteX Corporation)
500 parts of water 500 parts of isopropyl alcohol

(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 0.08 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 D>
Water-based polyester resin (anionic, softening point 130-140 ° C.) 100 parts (trade name ES901A, manufactured by Nagase ChemteX Corporation)
500 parts of water 500 parts of isopropyl alcohol

(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 0.08 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 E>
100 parts of water-soluble nylon resin (nonionic water-based amide resin) (trade name FS500, manufactured by Nagase ChemteX Corporation)
500 parts of water 500 parts of isopropyl alcohol

(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 0.08 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 F>
Polyvinyl pyrrolidone resin (K-90, manufactured by ISP) 10 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. The adhesive layer coating liquid A used in Example 1 is applied to the surface opposite to the surface on which the heat resistant slipping layer of the substrate is provided, by gravure coating so that the dry coating amount becomes 0.4 g / m ^2. The adhesive layer was formed by applying and drying. 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 4.

(Comparative Example 5)
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 liquid B used in Example 2 is applied to the surface opposite to the surface on which the heat-resistant slip layer of the substrate is provided, by gravure coating so that the dry coating amount is 0.4 g / m ^2. The adhesive layer was formed by applying and drying. 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 5.

<Reflection density>
Using the thermal transfer sheets of each of the examples and comparative examples prepared above, in combination with a dedicated thermal transfer image-receiving sheet for an OLIMPUS P-400 printer, printing was performed under the following conditions, and a Macbeth reflection densitometer RD-918. The reflection density was measured.
(Printing conditions)
Thermal head: KGT-217-12MPL20 (manufactured by Kyocera Corporation)
Heating element average resistance: 3139 (Ω)
Main scanning direction printing density; 300 dpi
Sub-scanning direction print density; 300 dpi
Applied power: 0.10 (w / dot)
1 line cycle: 5 (msec.)
Printing start temperature; 40 (° C)
Applied pulse (gradation control method): Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 in one line period and having a pulse length obtained by equally dividing one line period into 256 The duty ratio of the divided pulses was fixed to 70%, and the number of pulses per line period was divided into 15 from 0 to 255. Thereby, different energy can be given to 15 steps.

  About the printed matter in each of the above Examples and Comparative Examples, the reflection density at the 240th gradation (shadow portion) was measured.

<Releasability evaluation>
Under the same printing conditions as in the case of the reflection density measurement described above, the entire surface of the printed material was printed with a solid printing pattern (gradation value 255/255: density max), and when the printing was performed, It was visually examined whether the dye layer and the thermal transfer image-receiving sheet were thermally fused or whether so-called abnormal transfer occurred in which the dye layer was transferred to the transfer material.
Evaluation was performed according to the following criteria.
○: The dye layer and the thermal transfer image-receiving sheet are not thermally fused and abnormal transfer does not occur.
X: The dye layer and the thermal transfer image-receiving sheet are thermally fused or abnormal transfer occurs.

The measurement results of the reflection density and the results of the releasability evaluation are as shown in Table 1 below.

  From the above results, all the examples in which the adhesive layer contains a water-soluble resin containing active hydrogen and a water-soluble curing agent have a high reflection density of 1.7 or more. In Examples 1, 2, and 3, good results were obtained for the releasability.

Comparative Examples 1 to 3 do not contain a water-soluble resin containing active hydrogen and a water-soluble curing agent in the adhesive layer, and Comparative Examples 4 and 5 have a coating amount of 0.4 g / m when the adhesive layer is dried. ^2, which is larger than the range of 0.01 to 0.3 g / m ^{2. In} Comparative Examples 1 to 5, the reflection density is less than 1.7, which is satisfactory as a high density printed matter. Absent. In Comparative Examples 1 and 2, in the releasability, the dye layer and the thermal transfer image-receiving sheet were thermally fused or abnormal transfer occurred.

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 (4)

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 contains a water-soluble resin containing active hydrogen and water-soluble curing. A thermal transfer sheet comprising an agent and the water-soluble resin is a water-soluble nylon resin or an allylamine resin . 2. The thermal transfer sheet according to claim 1, wherein the substrate has a surface subjected to corona treatment, and an adhesive layer is provided on the corona treatment surface. The thermal transfer sheet according to claim 1, wherein the water-soluble curing agent is an epoxy curing agent or a carbodiimide curing agent. The thermal transfer sheet according to claim 1, wherein the adhesive layer has a coating amount of 0.01 to 0.3 g / m ² when dried .

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