JP2018176557A - Thermal transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet in which blur of an image in printing hardly occurs.SOLUTION: A thermal transfer image receiving sheet 104 is configured so that on one surface of a base material 100, a heat insulation layer 101, an intermediate layer 102, and a dye stuff reception layer 103 are laminated in this order. The dye stuff reception layer 103 is configured so that at least a partial portion thereof is formed by arranging plural film-state pieces 103a at an interval 103b in a direction orthogonal to a thickness direction of the dye stuff reception layer 103. The film-state piece 103a is formed into a size at which the film-state piece can be stored in a virtual circle whose diameter is 120 μm, and the interval 103b is 0.5 μm or more and less than 1.0 μm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a thermal transfer image receiving sheet.

  2. Description of the Related Art Conventionally, a sublimation thermal transfer system, a melt thermal transfer system, or the like has been employed as a system for forming characters, images, and the like on a transferee. For example, in the case of the sublimation type thermal transfer system, the surface of the thermal transfer layer of a thermal transfer recording medium provided with a thermal transfer layer containing a dye, a binder and the like on a support, and a dye receiving layer for receiving dye on another support The dye transfer layer is superposed on the surface of the dye-receptive layer, and the surface of the thermal transfer recording medium which is not provided with heat is heated by a thermal head or the like controlled by characters or image information to sublime the dye in the thermal transfer layer. And transfer to the dye receptive layer to form the desired character or image.

  On the other hand, in the case of the melt-type thermal transfer system, the surface of the thermal transfer layer of a thermal transfer recording medium provided with a thermally fusible thermal transfer layer containing a pigment, wax and the like on a support and a heat transferable surface provided with a receptive layer on another support The surface of the body is superimposed on the surface of the receiving layer, and the thermal transfer layer is fused by heating with a thermal head or the like, and transferred to the receiving layer to form a desired character or image. Among these methods, the sublimation thermal transfer method is widely adopted for monochrome printing such as characters and diagrams, and color printing such as digital camera images or computer graphics images.

  By the way, in the case of the sublimation type thermal transfer system, it is necessary to develop a high image density in a short time as the speed of the printer is increased, so that a dye receiving layer having high dyeability is required for the heat transfer member. If a resin with a low glass transition temperature with a large thermal diffusion of the dye is used for the dye receptive layer in order to enhance the dyeability, high-density printed matter can be obtained because the dye is easily dyed. There is a problem that the printed image blurs because it is large.

In order to solve the above problems, the acrylic resin copolymer comprising a specific monomer is contained in the dye-receptive layer using a copolymer having styrene and acrylonitrile as monomers, which is excellent in blocking resistance. The glass transition point of the resin can be lowered and softened. As a result, the sensitivity of the dye receptive layer is improved, and the dye is sufficiently diffused into the dye receptive layer, so that a heat-sensitive transfer sheet having high light resistance of the image, excellent light resistance, and small bleeding is obtained. (See Patent Document 1).
Also, a thermal transfer image receiving sheet has been proposed which has a dye receiving layer containing a resin having a specific glass transition temperature, a heat insulating layer, and an intermediate layer containing a specific polyvinyl alcohol and a specific colloidal silica (see Patent Document 2). . Bleeding can be improved by suppressing the migration of the dye from the dye-receptive layer to the intermediate layer with a low-adhesion colloidal silica.

Patent No. 5810799 Patent No. 5624454 gazette

However, although the techniques disclosed in Patent Document 1 and Patent Document 2 can suppress bleeding in a storage environment (mainly in a high temperature and high humidity environment), it is difficult to suppress bleeding during printing (sharpness). The
In view of the above problems, it is an object of the present invention to provide a thermal transfer image receiving sheet in which bleeding of an image during printing is less likely to occur.

  The thermal transfer image receiving sheet according to one aspect of the present invention is a thermal transfer image receiving sheet in which a heat insulating layer, an intermediate layer, and a dye receiving layer are laminated in this order on one surface of a substrate, and the dye receiving layer is At least a partial region is formed by arranging a plurality of film-like pieces at intervals in a direction orthogonal to the thickness direction of the dye receiving layer, and the film-like pieces are accommodated in a virtual circle having a diameter of 120 μm. The gist is that the size is possible and the distance is 0.5 μm or more and less than 1.0 μm.

  The thermal transfer image receiving sheet according to the present invention is less likely to cause image bleeding at the time of printing.

FIG. 1 is a schematic plan view showing an embodiment of a thermal transfer image receiving sheet according to the present invention. FIG. 1 is a schematic cross-sectional view showing an embodiment of a thermal transfer image receiving sheet according to the present invention. It is a schematic cross section which shows the conventional thermal transfer image receiving sheet.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The thermal transfer image receiving sheet 104 of the present embodiment shown in FIGS. 1 and 2 has a heat insulating layer 101, an intermediate layer 102, and a dye receiving layer 103 laminated in this order on one surface of a substrate 100. The dye-receptive layer 103 is formed by arranging at least a part of the film-like pieces 103a at intervals 103b in a direction perpendicular to the thickness direction of the dye-receptive layer 103. As shown in FIG. 1, each of the plurality of film-like pieces 103a has a size that can be accommodated in a virtual circle (a circle shown by a dotted line in FIG. 1) having a diameter of 120 μm. Moreover, as for the space | interval 103b of filmy piece 103a, all are 0.5 micrometer or more and less than 1.0 micrometer.

  In the conventional thermal transfer image receiving sheet 104, as shown in FIG. 3, the dye receiving layer 103 is formed of one film-like material which is continuous in the direction orthogonal to the thickness direction of the dye receiving layer 103. On the other hand, in the thermal transfer image receiving sheet 104 of the present embodiment, the dye receiving layer 103 is constituted of a plurality of film-like pieces 103 a arranged with a gap 103 b in the direction orthogonal to the thickness direction of the dye receiving layer 103. ing.

With such a configuration, in the thermal transfer image receiving sheet 104 of the present embodiment, the dye received in the dye receiving layer 103 is diffused in the direction orthogonal to the thickness direction of the dye receiving layer 103 by the gap 103 b. Is suppressed. Therefore, bleeding of the image at the time of printing in the thermal transfer system is unlikely to occur.
In FIG. 3, for convenience of explanation, the same or corresponding parts as in FIG. 1 are given the same reference numerals as in FIG. 1.

Hereinafter, the thermal transfer image receiving sheet 104 of the present embodiment will be described in more detail.
〔Base material〕
The substrate 100 has a role of holding the heat insulating layer 101, the intermediate layer 102, and the dye receiving layer 103. Since heat is applied at the time of thermal transfer, the substrate 100 is preferably formed of a material having a mechanical strength that does not cause any problem in handling even in a heated state.

  As a material of such a base material 100, for example, capacitor paper, glassine paper, sulfuric acid paper, or high-grade paper, synthetic paper (polyolefin type, polystyrene type), high quality paper, art paper, coated paper, resin coated Paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internally added paper, paperboard etc., cellulose fiber paper, or polyester, polyacrylate, polycarbonate, polyurethane, polyimide, poly Ether imide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulf Films such as polyester, polyethersulfone, tetrafluoroethylene, perfluoroalkylvinylether, polyvinyl fluoride, tetrafluoroethylene • ethylene, tetrafluoroethylene • hexafluoropropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc. Moreover, the white opaque film formed into a film by adding a white pigment and a filler to these synthetic resins can also be used, and it is not specifically limited.

  Moreover, the laminated body by arbitrary combinations of the said base material can also be used as a base material. Representative examples of the laminate include cellulose fiber paper and synthetic paper, or synthetic paper of cellulose synthetic paper and plastic film. In the present invention, a commercially available base material can also be used, and, for example, RC paper (manufactured by Mitsubishi Paper Industries, Ltd., trade name) is preferable. The thickness of the substrate can be appropriately changed in accordance with the strength required for the thermal transfer image receiving sheet, heat resistance, etc., and the material of the material adopted as the substrate. Specifically, the thickness of the substrate is preferably in the range of 50 μm to 1000 μm, and more preferably in the range of 100 μm to 300 μm.

[Dye receiving layer]
The dye-receptive layer 103 forms and maintains an image on the surface of the dye-receptive layer 103 by receiving the sublimable dye transferred from the thermal transfer ink sheet at the time of image formation by thermal transfer and holding the received sublimable dye. be able to. The dye receiving layer 103 contains a binder resin, but may further contain a silicone release agent. According to a preferred embodiment, the dye-receptive layer 103 may further contain known additives such as a surfactant, a film-forming aid, a crosslinking agent, an antioxidant, and a fluorescent dye depending on various purposes.

  Binder resins include acrylic resins, vinyl chloride resins, polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer (salt and vinyl acetate resin), halogenation of polyvinylidene chloride, etc. Polymer, Polyvinyl acetate / acrylic copolymer, Vinyl polymer such as polyacrylate, Polystyrene resin, Polyamide resin, Copolymer resin of olefin such as ethylene and propylene and other vinyl monomers, Ionomer, Cellulose di Cellulose-based resins such as acetate, polycarbonates and the like, and mixed systems of these resins may be mentioned, with preference given to vinyl chloride-based resins. The binder resin is more preferably a vinyl chloride-based resin of at least one of vinyl chloride / vinyl acetate copolymer and vinyl chloride / acrylic copolymer.

As the releasing agent contained in the dye receiving layer 103, for example, various oils such as silicones, fluorines, and phosphates, surfactants, various fillers such as metal oxides and silica, waxes, etc. It can be used. These mold release agents may be used alone or in combination of two or more. Among them, it is preferable to use silicone oil.
The thickness of the dye receiving layer 103 can be in the range of 0.1 μm to 10 μm, and more preferably in the range of 0.2 μm to 8 μm.

The dye receptive layer 103 is not composed of one film-like material continuous in the direction orthogonal to the thickness direction of the dye receptive layer 103, but the spacing 103b in the direction orthogonal to the thickness direction of the dye receptive layer 103. And a plurality of film-like pieces 103a arranged side by side. Such a configuration suppresses the diffusion of the dye received by the dye receiving layer 103 in the direction orthogonal to the thickness direction of the dye receiving layer 103. Specifically, since the pitch of the thermal head of the printer is 300 DPI and about 85 μm, the size of the film piece 103 a is 120 μm or less, and the interval 103 b is 0.5 μm or more and less than 1.0 μm. If the interval 103 b is 1.0 μm or more, the interval 103 b may be noticeable after printing and the image quality may be degraded.
There is no particular limitation on the method for producing the dye-receptive layer 103 constituted by arranging a plurality of film-like pieces 103a at intervals 103b, but the drying conditions of the film, the addition amount of the film forming aid, It can produce by setting the addition amount of a hardening agent etc. suitably.

[Intermediate layer]
The thermal transfer image receiving sheet 104 of the present embodiment has at least one intermediate layer 102 between the heat insulating layer 101 and the dye receiving layer 103. By having the intermediate layer 102 forming the undercoat layer, solvent resistance, dye diffusion barrier during image storage under high temperature / high humidity, interlayer adhesion, white color imparting, hiding of glaring / unevenness of the substrate 100, and A function such as antistatic can be added. A publicly known means can be used as a means for forming the intermediate layer 102. For example, a method of adding an optical brightening agent, inorganic fine particles, hollow fine particles, conductive filler, or an organic conductive material such as polyaniline sulfonic acid to the intermediate layer 102 may be mentioned.

[Adiabatic layer]
The heat insulating layer 101 has a heat insulating property that can prevent the heat applied at the time of image formation by thermal transfer from being lost due to heat transfer to the substrate 100 or the like. The heat insulating layer 101 provided on one surface of the base material 100 can be a conventionally known one, which is made of hollow particles and a binder resin, a foamed polypropylene film, a foamed film such as a foamed polyethylene terephthalate, etc. And those using a composite film provided with a skin layer on one side or both sides of a foam film. However, when using a foam film etc. as the heat insulation layer 101, it is preferable to use a hollow particle, when the curl which generate | occur | produces in the surface of a cost and the adhesion | pasting process with the base material 100 is considered.

[Back layer]
In the thermal transfer image receiving sheet 104 of the present embodiment, a back surface layer may be provided on the surface of the base 100 opposite to the surface on which the heat insulation layer 101 is provided. The back surface layer is provided to improve the printer transportability, to prevent blocking with the dye receiving layer 103, and to prevent curling of the thermal transfer image receiving sheet before and after printing.

  Conventionally known materials can be used as the material used for the back surface layer. For example, polyolefin resins such as polyethylene resin and polypropylene resin, acrylic resins, polycarbonate resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyester resins, polystyrene resins, and binder resins such as polyamide can be used. Moreover, you may contain well-known additives, such as a filler and an antistatic agent, as needed.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the present invention is not limited to these examples.
Example 1
A high-quality paper with a thickness of 140 μm was used as a substrate, and a polyethylene resin was melt-extruded on one side to form a first polyethylene resin layer with a thickness of 30 μm. Moreover, the skin layer was provided on one side of the 40-micrometer-thick foamed polypropylene film used as a heat insulation layer.

  Next, melt the polyethylene resin on the surface of the base opposite to the side on which the first polyethylene resin layer is formed, or on the side of the foamed polypropylene film opposite to the side on which the skin layer is provided. It extruded and formed the 2nd polyethylene resin layer. And a base material and a foaming polypropylene film were bonded together by the sandwich lamination system so that a 2nd polyethylene resin layer might be pinched | interposed. At this time, the thickness of the second polyethylene resin layer was made to be 15 μm.

Next, on the surface of the foamed polypropylene film on which the skin layer was provided, the intermediate layer coating liquid was applied so that the solid content coating amount was 2 g / m ² . Then, drying was performed for 1 minute under the conditions of a temperature of 100 ° C. and a wind speed of 3 using a constant temperature drier DNF601 (hereinafter referred to as “oven”) manufactured by Yamato Scientific Co., Ltd. to form an intermediate layer. The composition of the intermediate layer coating liquid is 20 parts by mass of gelatin (trade name: Gelatin RR manufactured by Nitta Gelatin Co., Ltd.), 80 parts by mass of pure water, and epoxy crosslinking agent (trade name: Carbodilight manufactured by Nagase ChemteX Co., Ltd.) E-02) 4 parts by mass.

Furthermore, on the intermediate layer, the dye receiving layer coating solution was applied so that the solid content coating amount was 2.5 g / m ² . After drying for 1 minute under conditions of temperature 80 ° C. and wind speed 3 using an oven, drying is further carried out under conditions of temperature 100 ° C. and wind speed 3 for 2 minutes to form a dye receptive layer, and thermal transfer An image receiving sheet was obtained.

  The surface of the dye-receptive layer and the cross section of the thermal transfer image-receiving sheet are observed with an electron microscope (hereinafter referred to as "SEM"). The dye-receptive layer has a plurality of film-like pieces in the direction orthogonal to the thickness direction of the dye-receptive layer. It was formed by being lined up at intervals. The size of this film-like piece can be accommodated at maximum in a virtual circle with a diameter of 103 μm (that is, the film-like piece makes a virtual circle with a diameter of 103 μm approximately a circumscribed circle), and the interval is 0 0.5 to 0.7 μm. The results are shown in Table 1.

  In addition, the composition of the dye receptive layer coating solution is 100.00 parts by mass of a vinyl chloride / vinyl acetate copolymer emulsion (Vinibran 603 manufactured by Nisshin Chemical Co., Ltd., Tg = 63 ° C., solid content = 50 mass%), It is 0.25 parts by mass of ethylene glycol diethyl ether, and 0.17 parts by mass of a silicone release agent (dimethyl silicone NP2406 manufactured by Asahi Kasei Wacker Silicon Co., Ltd., solid content = 60% by mass).

Example 2
When the dye receptive layer coating solution is coated on the intermediate layer and dried in an oven, drying is performed under the conditions of a temperature of 80 ° C. and a wind speed of 5 for 1 minute, and then under the conditions of a temperature of 100 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Example 2 was obtained in the same manner as in Example 1 except that drying was further performed for 2 minutes to form a dye receiving layer.
When the surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM, the dye receiving layer was formed by arranging a plurality of film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye receiving layer. It had been. The size of this film-like piece can be accommodated at maximum in a virtual circle having a diameter of 111 μm (that is, the film-like piece makes a virtual circle having a diameter of 111 μm approximately a circumscribed circle), and the interval is 0 0.6-0.8 μm. The results are shown in Table 1.

[Example 3]
When the dye receptive layer coating solution is applied onto the intermediate layer and dried in an oven, drying is performed under the conditions of a temperature of 80 ° C. and a wind speed of 7 for 1 minute, and then under the conditions of a temperature of 100 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Example 3 was obtained in the same manner as in Example 1 except that drying was further performed for 2 minutes to form a dye-receiving layer.
When the surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM, the dye receiving layer was formed by arranging a plurality of film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye receiving layer. It had been. The size of this film-like piece can be accommodated at maximum in a virtual circle with a diameter of 120 μm (that is, the film-like piece makes a virtual circle with a diameter of 120 μm approximately a circumscribed circle), and the distance is 0 0.6-0.9 μm. The results are shown in Table 1.

Comparative Example 1
When the dye receptive layer coating solution is coated on the intermediate layer and dried in an oven, drying is performed for 10 minutes under conditions of a temperature of 80 ° C. and a wind speed of 1, and then under conditions of a temperature of 100 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Comparative Example 1 was obtained in the same manner as Example 1, except that drying was further performed for 2 minutes to form a dye-receiving layer.
The surface of the dye-receptive layer and the cross section of the thermal transfer image-receiving sheet were observed by SEM, and it was found that the dye-receptive layer consisted of one film-like material continuous in the direction orthogonal to the thickness direction of the dye-receptive layer (Table 1) In the above, “all continuous film” is shown).

Comparative Example 2
When the dye receptive layer coating solution is applied onto the intermediate layer and dried in an oven, drying is performed under the conditions of a temperature of 80 ° C. and a wind speed of 1 for 5 minutes, and then under the conditions of a temperature of 100 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Comparative Example 2 was obtained in the same manner as Example 1, except that drying was further performed for 2 minutes to form a dye-receiving layer.
The surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM. As a result, although a depression was observed on the surface of the dye receiving layer, the dye receiving layer was continuous in the direction orthogonal to the thickness direction of the dye receiving layer. It was composed of one film-like substance (in Table 1, it is shown as "all-surface continuous film").

Comparative Example 3
When the dye receptive layer coating solution is applied onto the intermediate layer and dried in an oven, drying is performed under the conditions of a temperature of 80 ° C. and a wind speed of 10 for 1 minute, and then under the conditions of a temperature of 100 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Comparative Example 3 was obtained in the same manner as in Example 1, except that drying was further performed for 2 minutes to form a dye receiving layer.
When the surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM, the dye receiving layer was formed by arranging a plurality of film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye receiving layer. It had been. The size of this film-like piece can be accommodated at maximum in a virtual circle with a diameter of 125 μm (that is, the film-like piece makes a virtual circle with a diameter of 125 μm approximately a circumscribed circle), and the interval is 0 7 to 0.9 μm. The results are shown in Table 1.

Comparative Example 4
When the dye receptive layer coating solution is coated on the intermediate layer and dried in an oven, drying is performed under the conditions of a temperature of 80 ° C. and a wind speed of 10 for 1 minute, and then under the conditions of a temperature of 110 ° C. and a wind speed of 3. A thermal transfer image-receiving sheet of Comparative Example 4 was obtained in the same manner as in Example 1 except that drying was further performed for 2 minutes to form a dye receiving layer.
When the surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM, the dye receiving layer was formed by arranging a plurality of film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye receiving layer. It had been. The size of this film-like piece can be accommodated at maximum in a virtual circle with a diameter of 132 μm (that is, the film-like piece makes a virtual circle with a diameter of 132 μm approximately a circumscribed circle), and the distance is 1 7 to 2.0 μm. The results are shown in Table 1.

Comparative Example 5
When the dye receptive layer coating liquid is applied onto the intermediate layer and dried in an oven, drying is carried out for 3 minutes under conditions of a temperature of 120 ° C. and a wind speed of 10 to form a dye receptive layer, In the same manner as in Example 1, a thermal transfer image receiving sheet of Comparative Example 5 was obtained.
When the surface of the dye receiving layer and the cross section of the thermal transfer image receiving sheet were observed by SEM, the dye receiving layer was formed by arranging a plurality of film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye receiving layer. It had been. The size of this film-like piece can be accommodated at maximum in an imaginary circle having a diameter of 207 μm (that is, the film-like piece has an imaginary circle having a diameter of 207 μm as a substantially circumscribed circle) and a distance of 4 7 to 5.0 μm. The results are shown in Table 1.

  Thermal transfer image-receiving sheets of Examples 1 to 3 and Comparative Examples 1 to 5, thermal transfer recording medium (thermal transfer ink sheet), and thermal printer for evaluation of resolution 300 × 300 DPI (pitch of thermal resistor of thermal head: 85 μm) A sublimation type thermal transfer printing was performed using this method. The thermal transfer recording medium was produced as follows.

Using a 4.5 μm thick polyethylene terephthalate film with an easy-adhesion treatment on one side as the substrate, the amount after drying is 1.0 g / m on the other side (non-easy-adhesion treated side) ^The heat resistant slipping layer coating solution was applied to be ² and dried. The composition of the heat-resistant lubricating layer coating solution is 50.0 parts by mass of a silicone-based acrylic graft polymer (US-350 manufactured by Toagosei Co., Ltd.) and 50.0 parts by mass of methyl ethyl ketone.

Next, a heat transfer layer coating solution having the following composition is applied to the easily adhesive-treated surface of the substrate with a heat resistant slip layer so that the applied amount after drying is 1.0 g / m ^2, and dried to obtain a heat transfer layer. Then, a thermal transfer recording medium was obtained.
Thermal transfer layer coating solution
C. I. Solvent Blue 36 2.5 parts by mass C.I. I. Solvent Blue 63 2.5 parts by mass polyvinyl acetal resin 5.0 parts by mass toluene 45.0 parts by mass methyl ethyl ketone 45.0 parts by mass

The image blur, the image density, and the image clearness were evaluated for each of the obtained prints as follows.
<Evaluation of image blur>
A thin line image with a line width (thickness) of 90 μm was printed, and the line width was measured to evaluate bleeding. In addition, evaluation of the image blur was performed by the following evaluation criteria. Moreover, the measurement of the line width was performed by a microscope.

:: The line width (thickness) is smaller than 140 μm, and it does not feel completely blurred visually.
Δ: The line width (thickness) is 140 μm or more and smaller than 190 μm, and it looks a little blurred visually, but there is no problem in practical use.
X: The line width (thickness) is 190 μm or more, and the line looks blurred and blurred visually, which is a problem in practical use.

<Evaluation of image density>
○: The maximum reflection density is 1.95 or more, and there is no problem in practical use.
Δ: The maximum reflection density is 1.90 or more and less than 1.95, and although it is slightly lower, there is no problem in practical use.
X: The highest reflection density is 1.85 or more and less than 1.90, and there is a problem in practical use.

<Evaluation of image sharpness>
The landscape image was printed and the image quality was evaluated. The evaluation of the image quality was performed based on the following criteria.
○: There is no missing dot and excellent sharpness.
Δ: Dot omission is observed, but there is no problem in practical use.
X: Dot missing is noticeable, and there is a practical problem.

  From the results of Examples 1 to 3, the dye receiving layer is formed by arranging a plurality of film-like pieces at intervals in a direction orthogonal to the thickness direction of the dye-receiving layer, and the size of the film-like pieces The image can be accommodated in a virtual circle having a diameter of 120 μm, and if the interval is 0.5 μm or more and less than 1.0 μm, bleeding of the image of the printed matter printed on the thermal transfer image receiving sheet, image density, image sharpness It is understood that the sex is excellent.

On the other hand, in Comparative Example 1, since the dye receptive layer is formed of one continuous film-like substance, there is no problem in the image density and the image clearness, but the direction orthogonal to the thickness direction of the dye receptive layer Due to the diffusion of the dye into the image, a large amount of image blur appeared.
Further, in Comparative Example 2, since there is a depression on the surface of the dye-receptive layer, a plurality of film-like pieces appear to be spaced apart at first glance, but from the SEM observation of the cross section, one continuous film The dye-receptive layer was composed of a solid. Therefore, the diffusion of the dye in the direction orthogonal to the thickness direction of the dye-receptive layer was not sufficiently suppressed, resulting in a large image blur.

In Comparative Example 3, although the distance was less than 1.0 μm, the result was a large blur. From the comparison with Example 3, it is considered that the cause of this result is that the film-like piece is too large for the line width (thickness) of the printed thin line image.
In Comparative Examples 4 and 5, the blur of the image was large because both the size and the interval of the film-like pieces were too large. Furthermore, the printing density was lowered and the image clearness was also bad because the interval was not completely filled with printing energy.

  The thermal transfer image receiving sheet of the present invention can be used for a sublimation thermal transfer printer, and various images can be easily formed in full color. Therefore, digital cameras for self-printing, cards such as identification cards, output products for amusement It can be widely used.

100 ··· Base material 101 · · · Heat insulation layer 102 · · · Intermediate layer 103 · · · Dye receiving layer 103

Claims (2)

A thermal transfer image receiving sheet comprising a heat insulating layer, an intermediate layer, and a dye receiving layer laminated in this order on one side of a substrate,
The dye-receptive layer is formed by arranging at least a part of the film-like pieces at intervals in a direction perpendicular to the thickness direction of the dye-receptive layer.
The thermal transfer image-receiving sheet, wherein the film-like pieces have a size that can be accommodated in a virtual circle having a diameter of 120 μm, and the interval is 0.5 μm or more and less than 1.0 μm.   The thermal transfer image-receiving sheet according to claim 1, wherein the dye receiving layer contains a vinyl chloride resin, and the vinyl chloride resin is at least one of a vinyl chloride / vinyl acetate copolymer and a vinyl chloride / acrylic copolymer.

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