JP2021066153A - Thermal transfer image-receiving sheet - Google Patents

Abstract

To provide a thermal transfer image-receiving sheet which can obtain a uniform image having high density and has high adhesion.SOLUTION: A thermal transfer image-receiving sheet has hollow layers and a dye receiving layer in this order on at least one surface side of a base material. The hollow layers are layers having at least hollow particles and a binder resin, and are composed of at least two or more layers. In the hollow layers composed of the two or more layers, the hollow layer on a side closest to the base material contains a thickener, and a ratio of a thickener to the resin is reduced toward the hollow layer on a farther side from the hollow layer on a side closest to the base material, and the binder resin contains at least one rubber of natural rubber and synthetic rubber.SELECTED DRAWING: Figure 1

Description

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

Generally, the heat-sensitive transfer recording medium includes an ink ribbon used in a heat-sensitive transfer printer and a heat transfer image receiving sheet which is a transfer target. The ink ribbon is provided with a heat-sensitive transfer layer on one surface of the base material and a heat-resistant slipping layer (backcoat layer) on the other side of the base material. Here, the heat-sensitive transfer layer is a layer of ink, and the heat generated in the thermal head of the printer causes the dye contained in the ink to be thermally transferred (dye transfer method) or the ink to be melted (melt transfer method). , The heat transfer is transferred to the image receiving sheet side. When the heat transfer image receiving sheet is applied to the dye transfer method, the dye receiving layer is provided on one surface of the base material, and the dye receiving layer uses the heat transfer dye transferred from the ink ribbon described above. It receives and forms an image.

Currently, among the heat-sensitive transfer methods, the dye transfer method can easily form various images in full color in addition to improving the functionality of the printer, so self-printing of digital cameras, cards such as identification cards, output products for amusement, etc. , Widely used.

Along with the diversification of the above-mentioned applications, there has been a growing demand for miniaturization, high speed, low cost, environmental compatibility, and durability to the obtained printed matter. In recent years, the same surface of the base material of the ink ribbon has been sought. A heat-sensitive transfer recording medium provided with a plurality of dye layers, in which protective layers and the like that impart durability to the printed matter are arranged side by side so as not to overlap with each other, has become widespread.

Under the above circumstances, with the diversification and widespread use of thermal transfer image sheets, the purpose is to improve the heat insulation of the heat transfer image receiving sheet against heat from the thermal head and the cushioning property to improve the image quality of the printed matter. , A thermal transfer image receiving sheet in which a hollow layer having fine bubbles is provided on the surface of the base material or between the base material and the dye receiving layer has been proposed. The hollow layer is formed by the method described in Patent Document 1 in which a film having air bubbles inside is bonded to a base material, or by applying a coating liquid in which hollow particles and a binder resin are mixed. The method described in Patent Document 2 and the like can be mentioned.

Japanese Unexamined Patent Publication No. 1-130989 Japanese Unexamined Patent Publication No. 8-25813

However, the method of forming a hollow layer on the heat transfer image receiving sheet by adhering the film to the base material has a problem that curling is likely to occur due to heat shrinkage of the film. On the other hand, the method of forming the hollow layer by coating has an advantage that it is relatively easy to prevent the occurrence of curl.

Further, as described above, the hollow layer also has the purpose of enhancing the cushioning property. Therefore, it is desirable that the material forming the hollow layer has high flexibility. At the same time, in order to improve the smoothness of the surface after printing, it is desirable that the stability after applying pressure is also high. Examples of the material satisfying the above two performances include rubbers such as natural rubber and synthetic rubber such as styrene-butadiene rubber (SBR).

When forming a hollow layer on a heat transfer image receiving sheet by applying hollow particles and a binder resin, in order to give a uniform appearance to the printed matter, a smooth surface should be provided not only on the surface of the image receiving sheet but also on the surface of the hollow layer. It needs to be configured. However, when the drying speed of the hollow layer ink is high, the hollow particles are present in a high concentration on the surface as the coating liquid surface recedes, and as a result, the surface of the hollow layer derived from the hollow particles becomes uneven, and the resulting print is obtained. The image of an object may be uneven. This is particularly remarkable when the viscosity of the hollow layer ink is high and the coating amount is large.

On the other hand, the movement of the hollow particles to the surface side in the drying process leads to an improvement in the adhesion between the base material and the hollow layer due to the presence of the binder resin at a higher concentration on the base material side. It works in your favor.

The present invention has been made by paying attention to the above points, and an object of the present invention is to provide a heat transfer image receiving sheet which can obtain a uniform image and has excellent adhesion between a hollow layer and a base material.

In order to solve the problem, in the thermal transfer image receiving sheet according to one aspect of the present invention, a hollow layer and a dye receiving layer are formed in this order on at least one surface side of the base material, and the hollow layer is formed with at least hollow particles. A layer having a binder resin, which is composed of at least two layers or more, and among the hollow layers composed of the two or more layers, the hollow layer on the side closest to the base material contains a thickener, and from the above two layers or more. As the hollow layer is moving from the hollow layer closest to the base material to the hollow layer farther from the base material, the ratio of the thickener to the resin decreases, and the binder resin is a rubber of at least one of natural rubber and synthetic rubber. The gist is to include.

The gist of the heat transfer image receiving sheet according to one aspect of the present invention is that the hollow layer V1 existing at the position farthest from the base material among the hollow layers composed of the above two or more layers does not contain a thickener.

The thermal transfer image receiving sheet according to one aspect of the present invention is the total film thickness t1 of the hollow layer V1 existing at the position farthest from the base material and the total film thickness of the hollow layers other than V1 among the hollow layers composed of the above two or more layers. The gist is that t2 is within the range of the following equation.
0.05 ≦ t1 / t2 ≦ 0.25

According to one aspect of the present invention, it is possible to obtain a thermal transfer image receiving sheet capable of obtaining a uniform image.

This is an example of a cross-sectional view showing a schematic configuration of a thermal transfer image receiving sheet according to an embodiment of the present invention. This is an example of a cross-sectional view showing another schematic configuration of the thermal transfer image receiving sheet according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described with reference to the drawings.
[Overall configuration of thermal transfer image receiving sheet]
As shown in FIG. 1, the heat transfer image receiving sheet of the present embodiment includes a hollow layer 200 and a dye receiving layer 300 including a base material 100 and at least two layers of a hollow layer A210 and a hollow layer B220.

[Structure of base material 100]
The base material 100 is not limited except that heat resistance and strength that are not softened and deformed by heat pressure in thermal transfer are required, and conventionally known base materials 100 are used.

Examples of the material of the base material 100 include condenser paper, glassin paper, sulfated paper, high-sized paper, synthetic paper (dioxide-based, polystyrene-based), high-quality paper, art paper, coated paper, resin-coated paper, and cast. Coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin inner sheet paper, paperboard, etc., cellulose fiber paper, or polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, Cellulous derivatives, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene , Perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychlorotrifluoroethylene, polyvinylidene fluoride and the like, and white pigments on these synthetic resins. A white opaque film formed by adding a filler or a filler can also be used, and is not particularly limited. Further, as the base material 100, a laminate made of any combination of base materials made of the above materials can also be used. Examples of typical laminates include synthetic paper made of cellulose fiber paper and synthetic paper, or synthetic paper made of cellulose synthetic paper and plastic film.

Further, the thickness of the base material 100 (the length in the vertical direction in FIG. 1) is appropriately changed according to the strength and heat resistance required for the heat transfer image receiving sheet and the material of the material used as the base material. It is possible, and specifically, it is preferably in the range of 50 μm or more and 1000 μm or less, and more preferably in the range of 100 μm or more and 300 μm or less.

[Structure of hollow layer 200]
The hollow layer 200 prevents the heat applied during image formation from being lost due to propagation to the base material 100 side, and enhances the cushioning property so that the surface of the heat transfer image receiving sheet can follow the thermal head. It can be enhanced to obtain a uniform printing screen, and is composed of at least two layers, a hollow layer A210 and a hollow layer B220, from the side closer to the base material. As shown in FIG. 2, it may be composed of three layers of the hollow layer A210, the hollow layer B220, and the hollow layer C230, or more layers.

The hollow layer A210 and the hollow layer B220 are layers containing at least hollow particles and a binder resin. The binder resin contains at least one of natural rubber and synthetic rubber as a main component. The main component refers to, for example, 80% by weight or more, preferably 90% by weight or more of the binder resin.

The hollow layer A210 and the hollow layer B220 are formed by containing hollow particles in the aqueous colloid of at least one of the natural rubber and the synthetic rubber constituting the binder resin, and further adding additives such as a surfactant and a stabilizer. An appropriately added ink is used as a coating liquid for forming a hollow layer, and the coating liquid is applied onto the base material 100 and dried to form the hollow layer A210 and the hollow layer B220.

As an example of the binder resin used for the hollow layer A210 and the hollow layer B220, in addition to natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber (SBR), chloroprene rubber, nitrile rubber, butyl rubber, chlorinated butyl rubber, and ethylene. Synthetic rubbers such as propylene rubber, acrylic rubber, fluororubber, epichlorohydrin rubber, urethane rubber, and silicone rubber are mentioned, and natural rubber, SBR, butadiene rubber, chlorinated butyl rubber, and acrylic rubber are preferable. In particular, at least one of natural rubber and SBR is more preferable. By using the rubber as the binder resin, the cushioning property of the hollow layer is improved, so that the followability of the heat transfer image receiving sheet to the thermal head is increased, and a uniform image can be obtained.

The binder resin used for the hollow layer A210 and the hollow layer B220 is required to be an aqueous colloid dispersed in an aqueous dispersion medium in its coating. By using an aqueous coating liquid, it is possible to suppress adverse effects on the environment during the production of the heat transfer image receiving sheet.

Examples of the hollow particles used in the hollow layer A210 and the hollow layer B220 include hollow particles whose outer shell is made of silica, calcium carbonate, ceramic, acrylic resin, acrylic-styrene resin, or the like. The voids of the hollow particles may be porous as well as single pores. Further, the void portion of the hollow particles may contain not only air but also a liquid that can volatilize after drying, such as water. It is assumed that the hollow particles do not contain heat-expandable microcapsules.

The particle size of the hollow particles is preferably 0.1 μm or more and 5.0 μm or less. If the particle size is less than this range, sufficient voids are not formed in the hollow layer and the heat insulating property is insufficient, while if it exceeds this range, the surface of the hollow layer becomes excessively uneven, resulting in a dye. The smoothness of the receiving layer surface is also lost, resulting in poor image quality of the printed matter.

The porosity of the hollow particles is preferably 20% or more and 60% or less. If the porosity is less than 20%, sufficient voids are not formed in the hollow layer and the heat insulating property is insufficient, while if it exceeds 60%, the hollow layer cannot withstand the pressure applied to the image receiving sheet at the time of printing. The hollow layer is crushed, and a predetermined heat insulating property cannot be obtained, or the image quality of the printed matter is poor.

Among the hollow layers 200, the hollow layer A210 existing at least at a position closest to the base material contains a thickener that increases the viscosity at the time of ink. By containing the thickener, the movement of the particles is suppressed, causing uneven distribution of the hollow particles on the coating film surface due to the recession of the ink surface during drying and uneven distribution of the resin on the substrate side, resulting in a hollow layer. It is possible to improve the adhesion between the base material and the base material.

The content of the thickener is preferably 0.3% by weight or more and 2% by weight or less, and more preferably 0.5% by weight or more and 1.5% by weight or less with respect to the binder resin of the hollow layer. When the content of the thickener is within the above range, it is possible to obtain sufficient coating suitability while suppressing the movement of the hollow particles during drying and controlling the position in the film.

As described above, the hollow layer 200 is composed of at least two layers, and the ratio of the thickener contained in those layers to the binder resin is set to the hollow layer on the side farthest from the hollow layer on the side closest to the base material. The composition decreases as it goes toward it. It is possible to prevent peeling inside the hollow layer at the time of printing by adopting a configuration in which the number decreases in order from the base material side.

It is desirable that the hollow layer V1 of the hollow layer 200, which exists at the position farthest from the base material, does not contain a thickener. Since the hollow layer V1 does not contain a thickener, the smoothness of the surface of the hollow layer 200 can be improved, so that the image quality of the printed matter can be improved.

It is desirable that the film thickness t1 of the hollow layer V1 existing at the position farthest from the base material of the hollow layer 200 and the total film thickness t2 of the hollow layers other than V1 are within the range of the following formula.
0.05 ≦ t1 / t2 ≦ 0.25
When the relationship of the film thickness is within the range of the above formula, the image quality of the printed matter is improved by increasing the smoothness of the surface of the hollow layer, and a high color density is obtained by further improving the heat insulating property. Is possible.

[Structure of Dye Receiving Layer 300]
The dye receiving layer 300 receives the heat transfer dye transferred from the ink ribbon at the time of image formation by heat transfer, and forms and maintains the image by retaining the received heat transfer dye.

The dye receiving layer 300 is formed by, for example, appropriately adding additives such as a curing agent and a mold release agent to the binder resin to prepare a coating liquid for forming the dye receiving layer 300, applying the coating liquid, and drying the coating liquid.
Examples of the binder resin used for the dye receiving layer 300 include acrylic resin, vinyl chloride resin, polyolefin resin such as polyethylene and polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer (salt vinegar vinyl resin). , Halogenized polymer such as polyvinylidene chloride, polyvinyl acetate / acrylic copolymer, vinyl polymer such as polyacrylic acid ester, polystyrene resin, polyamide resin, olefin such as ethylene and propylene, and other vinyl monomers. Examples thereof include a polymerization system resin, a cellulose resin such as ionomer and cellulose diacetate, a polycarbonate and the like, and a mixed system of these resins, and a vinyl chloride resin is preferable. Among the vinyl chloride meter resins, at least one kind of vinyl chloride resin selected from vinyl chloride / vinyl acetate copolymer and vinyl chloride / acrylic copolymer is more preferable.

Further, as a curing agent, it may be appropriately added depending on the binder resin. As an example of the curing agent, isocyanates such as tolylene diisocyanate, triphenylmethane triisocyanate, and tetramethylxylene diisocyanate, and derivatives thereof can be used.

Further, a mold release agent may be appropriately added to the dye receiving layer 300. Examples of mold release agents include amino-modified silicone, alcohol-modified silicone, vinyl-modified silicone, urethane-modified silicone, epoxy-modified silicone, polyester-modified silicone, polyether-modified silicone, polyester-modified silicone, acrylic-modified silicone, aralkyl-modified silicone, and Examples thereof include silicone oils such as amide-modified silicones. In the present invention, these can be mixed or polymerized using various reactions before use.

When the content of the silicone release agent increases, background stains occur. Therefore, the silicone release agent is preferably 2% or less with respect to the solid content of the binder resin of the dye receiving layer 300.

Further, an adhesive layer may be provided for the purpose of improving the adhesiveness between the base material 100 and the hollow layer 200, or between the hollow layer 200 and the dye receiving layer 300. The material constituting the adhesive layer is not particularly limited, and examples thereof include polyolefin resins such as polyethylene, urethane resins, acrylic resins, and polyester resins. Among these, urethane-based resin and acrylic-based resin are preferable. Further, a known additive such as a filler, an antistatic agent, or a fluorescent whitening agent may be added to the material forming the adhesive layer, if necessary.

Further, a back surface layer may be provided on the surface of the base material 100 opposite to the dye receiving layer 300. The back surface layer is provided for the purpose of improving transportability in the printer, preventing blocking from the dye receiving layer 300 during storage, and improving writability. The material constituting the back surface layer is not particularly limited, but for example, polyolefin resins such as polyethylene resin and polypropylene resin, acrylic resins, polycarbonate resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyester resins, etc. Examples thereof include polystyrene-based resins and polyamide-based resins. Further, a known additive such as a filler, an antistatic agent, or a fluorescent whitening agent may be added to the material forming the back surface layer, if necessary.

Hereinafter, the effects of the present invention will be verified using Examples (Examples 1 to 8 and Comparative Examples 1 to 4) with reference to FIG. In addition, when it is described as "part" in the following description, it indicates the mass standard unless otherwise specified. Moreover, the present invention is not limited to the following examples.

In the examples and comparative examples described below, the heat transfer image receiving sheet hollow layer base material and the heat transfer image receiving sheet were produced by the methods shown below.

[Preparation of thermal transfer image receiving sheet hollow layer base material]
<Example 1>
As a base material, 188 μm easy-adhesion-treated PET (WV = 0.2) was used. A hollow layer ink having the composition shown below (hereinafter referred to as "hollow layer ink-1") is applied to one surface by a gravure coating method so that the coating thickness after drying is 3.8 μm. The hollow layer A210 was formed by drying at a temperature of 100 ° C. for 10 minutes. Then, on the hollow layer A210, a hollow layer ink having the composition shown below (hereinafter, referred to as “hollow layer ink-2”) is applied by a gravure coating method so that the coating thickness after drying becomes 0.2 μm. By applying and drying at a temperature of 100 ° C. for 5 minutes, a hollow layer B220 was formed, and a heat transfer image receiving sheet hollow layer base material of Example 1 was prepared.

・ Hollow layer ink-1
The composition of the hollow layer ink-1 is as follows.
SBR Latex (Product Name: LX430, Made by Zeon Corporation, NV: 49%) 32.8 Parts Hollow Particle Dispersion Liquid (Product Name: Low Pake SN-1055,
Dow Chemical, NV: 26.5%) 48.5 parts Thickener (trade name: Thickener 929S, San Nopco, NV: 12%) 18.7 parts

・ Hollow layer ink-2
The composition of the hollow layer ink-2 is as follows.
SBR Latex (Product Name: LX430) 34.1 Parts Hollow Particle Dispersion Liquid (Product Name: Low Pake SN-1055) 50.4 Parts Thickener (Product Name: Thinner 929S) 9.7 Parts Pure Water 5.8 Parts

The ratio (solid content ratio) of the thickener of the hollow layer ink-1 to the resin (SBR latex) is as follows.
(18.7 x 12%) / (32.8 x 49%) = 14%

<Example 2>
In the thermal transfer image receiving sheet hollow layer base material produced in Example 1, the coating thickness of the hollow layer A210 after drying was 3.2 μm, and the coating thickness of the hollow layer B220 after drying was 0.8 μm. The thermal transfer image receiving sheet hollow layer base material of Example 2 was obtained in the same manner as the thermal transfer image receiving sheet hollow layer base material of Example 2.

<Example 3>
The hollow layer ink-1 was applied onto the base material so that the film thickness after drying was 2.6 μm, and dried at a temperature of 100 ° C. for 10 minutes to form the hollow layer A210. Then, on the hollow layer A210, a hollow layer ink having the composition shown below (hereinafter referred to as "hollow layer ink-3") is applied by a gravure coating method so that the coating thickness after drying is 1.2 μm. The hollow layer B220 is formed by applying and drying at a temperature of 100 ° C. for 5 minutes, and then the hollow layer ink-2 is further applied on the hollow layer B220 by the gravure coating method, and the coating thickness after drying is 0. The thermal transfer image receiving sheet of Example 3 was the same as that of the hollow layer substrate, except that the hollow layer C230 was formed by applying the ink to 2 μm and drying at a temperature of 100 ° C. for 5 minutes. A sheet hollow layer base material was obtained.

・ Hollow layer ink-3
The composition of the hollow layer ink-3 is as follows.
SBR Latex (Product Name: LX430) 33.5 Parts Hollow Particle Dispersion Liquid (Product Name: Low Pake SN-1055) 49.5 Parts Thickener (Product Name: Thinner 929S) 13.7 Parts Pure Water 3.3 Parts

<Example 4>
In the heat transfer image receiving sheet hollow layer base material produced in Example 3, the same procedure as in the heat transfer image receiving sheet hollow layer base material of Example 3 was carried out except that the ink of the hollow layer C230 was the following hollow layer ink-4. A hollow layer base material for the heat transfer image receiving sheet of Example 4 was obtained.

・ Hollow layer ink-4
The composition of the hollow layer ink-4 is as follows.
SBR Latex (Product Name: LX430) 35.5 Parts Hollow Particle Dispersion Liquid (Product Name: Low Pake SN-1055) 52.5 Parts Pure Water 12.0 Parts

<Example 5>
In the thermal transfer image receiving sheet hollow layer base material produced in Example 1, the coating thickness of the hollow layer A210 after drying was 3.5 μm, and the coating thickness of the hollow layer B220 after drying was 0.5 μm. The thermal transfer image receiving sheet hollow layer base material of Example 5 was obtained in the same manner as the thermal transfer image receiving sheet hollow layer base material of Example 1.

<Example 6>
In the heat transfer image receiving sheet hollow layer base material produced in Example 4, the coating thickness of the hollow layer A210 after drying is 2.0 μm, the coating thickness of the hollow layer B220 after drying is 1.5 μm, and the drying of the hollow layer C230 is performed. A heat transfer image receiving sheet hollow layer base material of Example 6 was obtained in the same manner as the heat transfer image receiving sheet hollow layer base material of Example 4 except that the coating thickness after that was set to 0.5 μm.

<Example 7>
In the thermal transfer image receiving sheet hollow layer base material produced in Example 1, except that the hollow layer A210 had a coating thickness of 3.9 μm after drying and the hollow layer B220 had a coating thickness of 0.1 μm after drying. The thermal transfer image receiving sheet hollow layer base material of Example 7 was obtained in the same manner as the thermal transfer image receiving sheet hollow layer base material of Example 1.

<Example 8>
In the thermal transfer image receiving sheet hollow layer base material produced in Example 1, except that the hollow layer A210 had a coating thickness of 3.0 μm after drying and the hollow layer B220 had a coating thickness of 1.0 μm after drying. The thermal transfer image receiving sheet hollow layer base material of Example 8 was obtained in the same manner as the thermal transfer image receiving sheet hollow layer base material of Example 1.

<Comparative example 1>
Comparative Example 1 was made in the same manner as the heat transfer image receiving sheet hollow layer base material of Example 1 except that the hollow layer 200 was made into only one layer having a coating thickness of 4.0 μm after drying with the hollow layer ink-1. A hollow layer base material for a heat transfer image receiving sheet was obtained.

<Comparative example 2>
In the heat transfer image receiving sheet hollow layer base material produced in Example 1, the hollow layer A210 is the same as that of the heat transfer image receiving sheet hollow layer base material of Example 1 except that the hollow layer ink-4 is used as described in Comparative Example. The hollow layer base material of the heat transfer image receiving sheet of No. 2 was obtained.

<Comparative example 3>
In the heat transfer image receiving sheet hollow layer base material produced in Example 3, the hollow layer A210 was the above-mentioned hollow layer ink-2, and the hollow layer C230 was the above-mentioned hollow layer ink-1. In the same manner as the heat transfer image receiving sheet hollow layer base material, the heat transfer image receiving sheet hollow layer base material of Comparative Example 3 was obtained.

<Comparative example 4>
In the heat transfer image receiving sheet hollow layer base material produced in Example 3, the hollow layer A210 is the above-mentioned hollow layer ink-3, the hollow layer B220 is the above-mentioned hollow layer ink-1, and the hollow layer C230 is the above-mentioned hollow layer ink-1. A heat transfer image receiving sheet hollow layer base material of Comparative Example 4 was obtained in the same manner as the heat transfer image receiving sheet hollow layer base material of Example 3 except that the hollow layer ink-2 was used.

[Formation of dye receiving layer]
Regarding the obtained heat transfer image receiving sheet hollow layer base material of Examples 1 to 8 and the heat transfer image receiving sheet hollow layer base material of Comparative Examples 1 to 4, the following dyes were received on the surface of the hollow layer opposite to the base material. The layer coating liquid was applied and dried so that the thickness after drying was 3 μm, and thermal transfer image receiving sheets of samples a to h and samples i to l were obtained, respectively.

-Dye receiving layer coating liquid The composition of the dye receiving layer coating liquid is as follows.
Vinyl chloride-acrylic emulsion (trade name: Viniblanc 900,
98.3 parts of polyether-modified silicone (trade name: KF-6012, manufactured by Shin-Etsu Chemical) 0.4 parts of isocyanate-based curing agent (trade name: DNW-6000, manufactured by DIC) ) 1.3 copies

[Making ink ribbon]
As a base material, a 4.5 μm polyethylene terephthalate film with easy-adhesion treatment on one side was used, and a heat-resistant slip layer coating liquid having the composition shown below was applied to the non-easy-adhesion-treated surface in an amount of 1.0 g / m ² and so as coated and dried to obtain a heat resistant slipping layer-substrate. Next, a thermal transfer layer coating liquid having the composition shown below is applied to the easily adhesive-treated surface of the base material with a heat-resistant slipping layer so that the coating amount after drying is 1.0 g / m ² , dried and thermally transferred. A layer was formed to obtain an ink ribbon.

-Heat-resistant slip layer coating liquid The composition of the heat-resistant slip layer coating liquid is as follows.
Silicone acrylic graft polymer (trade name: US-350, manufactured by Toagosei) 50.0 parts Methyl ethyl ketone 50.0 parts

-Thermal transfer layer coating liquid The composition of the thermal transfer layer coating liquid is as follows.
C. I. Solvent Blue 36 2.5 parts C.I. I. Solvent Blue 63 2.5 parts Polyvinyl acetal resin 5.0 parts Toluene 45.0 parts Methyl ethyl ketone 45.0 parts

[Evaluation]
-Evaluation of image quality Using the heat transfer image receiving sheets and ink ribbons of Examples 1 to 8 and Comparative Examples 1 to 4, solid images are printed at settings of 300 dpi, 10 msec / line, and 0.5 mJ / dot to evaluate the image quality. Was done. The image quality was evaluated according to the following criteria.
◯: The density of the printed matter is uniform and the image quality is excellent.
Δ: There is slight unevenness in the printed matter, but it is at a level where there is no problem in practical use.
X: There is a problem in practical use due to uneven shading on the printed matter.

-Adhesion evaluation Cellotape (registered trademark) is attached to the surface of the dye receiving layer of the heat transfer image receiving sheets of Examples 1 to 8 and Comparative Examples 1 to 4, and the coating film is not taken off by the cellophane tape (registered trademark). I confirmed. The evaluation was carried out according to the following criteria.
◯: The coating film is not taken by cellophane tape (registered trademark).
X: A coating film is applied to cellophane tape (registered trademark).

-Highest density evaluation Using the thermal transfer image receiving sheets and ink ribbons of Examples 1 to 8 and Comparative Examples 1 to 4, solid images were printed at settings of 300 dpi, 10 msec / line, and 0.7 mJ / dot, and X- The reflection density was measured in the status A of write528. The reflection density was evaluated according to the following criteria.
◯: OD is 2.2 or more.
Δ: OD is less than 2.2 and 2.0 or more.
X: OD is less than 2.0.

[Evaluation results]
Table 1 shows a list of evaluation results for each level.

As can be seen from the results shown in Table 1, the hollow layer is composed of at least two or more layers having hollow particles and a binder resin, and among the above two or more hollow layers, the side closest to the base material. The ratio of the thickener to the resin decreases as the hollow layer contains the thickener and the hollow layer composed of the two or more layers moves from the hollow layer closest to the base material to the hollow layer on the far side. By containing at least one of natural rubber and synthetic rubber in the binder resin, a heat transfer image receiving sheet having excellent image quality, adhesion, and density could be produced, and the effect of the invention could be confirmed.

On the other hand, in Comparative Example 1, since the hollow layer was composed of only one layer, the surface of the hollow layer could not be sufficiently smoothed, and sufficient image quality could not be obtained.

In Comparative Example 2, although the hollow layer is composed of two layers, the hollow layer on the side closest to the base material does not contain a thickener, so that sufficient voids between the hollow particles cannot be obtained. , A sufficient concentration could not be obtained.

In Comparative Examples 3 and 4, the hollow layer on the side closest to the base material contained the thickener, but as the hollow layer on the side closest to the base material moved toward the hollow layer on the far side, the thickener for the resin was added. Since the ratio did not decrease, sufficient cohesiveness between the hollow particles could not be obtained, and sufficient adhesion could not be obtained.

The thermal transfer image receiving sheet obtained by the present invention can be used in a sublimation transfer printer, and various images can be easily formed in full color in addition to high speed and high functionality of the printer. Therefore, self-printing of a digital camera , Cards such as identification cards, output materials for amusement, etc. can be widely used.

100 Base material 200 Hollow layer 210 Hollow layer A
220 Hollow layer B
230 Hollow layer C
300 dye receiving layer

Claims (3)

A hollow layer and a dye receiving layer are formed in this order on at least one surface side of the base material.
The hollow layer is a layer having at least hollow particles and a binder resin, and is composed of at least two or more layers.
Of the above two or more hollow layers, the hollow layer closest to the base material contains a thickener.
As the hollow layer composed of the above two or more layers moves from the hollow layer closest to the base material to the hollow layer on the far side, the ratio of the thickener to the resin decreases.
A heat transfer image receiving sheet, wherein the binder resin contains at least one rubber of natural rubber and synthetic rubber. The heat transfer image receiving sheet according to claim 1, wherein the hollow layer V1 existing at the position farthest from the base material among the hollow layers composed of two or more layers does not contain a thickener. Among the hollow layers composed of two or more layers, the film thickness t1 of the hollow layer V1 existing at the position farthest from the base material and the total film thickness t2 of the hollow layers other than V1 are within the range of the following formula. The thermal transfer image receiving sheet according to claim 1 or 2.
0.05 ≦ t1 / t2 ≦ 0.25

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