JP2002192842A - Thermal transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet having a quality feeling such as gloss, a surface shape or the like same to that of photographic printing paper, having high sensitivity, not generating the missing of printing or density irregularity and low in cost. SOLUTION: The thermal transfer image receiving sheet has paper based on cellulose as a base material and is formed by successively laminating a porous layer containing hollow particles and a binder resin for bonding the hollow particles and a receiving layer on the base material. The binder resin in the porous layer is a water soluble resin functioning as a size agent and an intermediate layer comprising an aqueous coating layer is interposed between the porous layer and the receiving layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet used in superposition with a thermal transfer sheet for sublimation transfer, and more particularly to a thermal transfer image-receiving sheet having the same texture as photographic printing paper, having high sensitivity and being free from missing images. The present invention relates to a thermal transfer image receiving sheet.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known. Among them, a recording material composed of a sublimable dye is supported on a base sheet such as paper or a plastic film, and can be dyed with a sublimable dye. A method of forming various full-color images on a thermal transfer image-receiving sheet having a dye-receiving layer provided on the surface of paper or a plastic film, for example, using a suitable thermal transfer image-receiving sheet has been proposed. In this method, since a sublimable dye is used as a coloring material, the density gradation can be freely adjusted, and a full-color image of a document can be expressed. In addition, since the image formed by the dye is extremely clear and excellent in transparency, it has excellent reproducibility of intermediate colors and gradation reproducibility, and it is possible to form high quality images comparable to silver halide photography It is.

As one of the image receiving sheets for the sublimation transfer recording system, a thermal transfer image receiving sheet using paper made of pulp as a main material has been proposed. An image-formed product formed on a thermal transfer image-receiving sheet using paper made of this pulp as a main raw material has the same texture as a printed product obtained by ordinary printing, such as surface gloss and thickness. The thermal transfer image receiving sheet using pulp-based paper as the base material has the same texture as photographic printing paper, such as texture and gloss, and unlike a thermal transfer image receiving sheet based on synthetic paper, it can be folded. It has advantages that are suitable for various uses, such as being capable of binding and filing even when several sheets are stacked. Also, because paper is cheaper than synthetic paper,
A thermal transfer image-receiving sheet using paper as a base material can be manufactured at low cost. A thermal transfer image-receiving sheet using this paper substrate is usually formed with one layer between the substrate and the dye-receiving layer, for example, a porous layer composed of resin and hollow particles, in order to supplement the cushioning properties of the substrate. Cushioning and heat insulating properties are provided to enhance the adhesion between the image receiving sheet and the thermal transfer sheet.

[0004]

When pulp-based paper is used as the base material, such paper has poor smoothness as compared with synthetic paper. Resulting in a poor thermal transfer image receiving sheet. Also, when a water-based porous layer containing hollow particles is applied to a base paper made of pulp as a main raw material, the moisture permeates excessively into the base paper, and after drying, the surface of the porous layer becomes uneven. As a result, the surface of the dye / dye receiving layer becomes uneven, so that an image with a lot of missing prints was obtained, and a high-quality thermal transfer image-receiving sheet could not be obtained.

[0005] In order to improve this, an undercoat layer is provided, or a base paper having a large surface coating amount such as cast coated paper is used to prevent water penetration. However, when the undercoat layer is provided, the layer configuration becomes extra, which increases the cost. Also, cast-coated paper is not preferred in terms of cost.

An object of the present invention is to provide a low-cost thermal transfer image-receiving sheet which has the same texture as that of photographic printing paper, such as gloss and surface shape, and has high sensitivity and is free from missing images and uneven density.

[0007]

Means for Solving the Problems As a result of research to solve the above-mentioned problems, the present inventor has found that a function as a surface sizing agent is required to reduce the rate of penetration of water into the base paper in the drying step. By using the water-soluble resin to be fulfilled as a binder resin to bind with the hollow particles in the porous layer, it is possible to delay the penetration of water into the base paper, and the surface of the porous layer has a high smoothness, and there is no printing loss. It has been found that a high-quality thermal transfer image-receiving sheet can be obtained, and the present invention has been completed.

[0008] The gist of the present invention is that "a heat transfer image-receiving sheet in which a porous layer containing hollow particles, an intermediate layer, and a dye-receiving layer are formed in this order on a paper containing cellulose as a base material. Wherein the resin that binds the hollow particles in the porous layer is a water-soluble resin. "

In the present invention, by using a high-molecular weight water-soluble resin having a particularly high viscosity and a high water retention as the water-soluble resin, it is possible to delay the penetration of water into the base material, and to improve the surface of the porous layer. And a high-quality thermal transfer image-receiving sheet with high print quality and no print omission can be obtained.

When a porous layer containing hollow particles is coated on a substrate, the higher the porosity of the porous layer, the higher the sensitivity and the higher the quality of the thermal transfer image-receiving sheet. Can be. In order to obtain excellent heat insulating properties and cushioning properties, the voids between the hollow particles in the porous layer must remain without being filled with the resin. However, when the amount of the resin is small, the binding force with the hollow particles is insufficient, and the porous layer is separated from the substrate.

The present inventor has searched for a resin capable of obtaining a high binding force to hollow particles with a small amount of resin, and has found that high molecular weight polyvinyl alcohol exhibits excellent binding force. Particularly, polyvinyl alcohol having an average degree of polymerization of 1000 or more has a strong binding force with hollow particles,
Even when it is added by weight, the porous layer does not peel off from the substrate, and a high-quality thermal transfer image-receiving sheet with high sensitivity and no printing loss can be obtained.

In the present invention, the intermediate layer is desirably formed by an aqueous coating solution. The intermediate layer formed by this aqueous coating solution functions as a solvent barrier layer for preventing the organic solvent in the dye receiving layer from eroding and destroying hollow particles in the porous layer. The aqueous coating liquid refers to an aqueous solution of a water-soluble resin, a dispersion of the resin, or an emulsion of the resin.

In the present invention, an intermediate layer containing a polyvinyl alcohol having a saponification ratio of 85 mol% or more and 98 mol% or less is desirable because it has excellent solvent resistance and dye-receiving layer adhesion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the thermal transfer image-receiving sheet of the present invention will be described below in detail.

FIG. 1 shows a thermal transfer sheet of the present invention. FIG.
As shown in (1), the thermal transfer image-receiving sheet has a substrate 1 made of paper mainly composed of cellulose, and has a function as a sizing agent for binding the hollow particles sequentially laminated on the substrate 1 and the hollow particles. It comprises a porous layer 2 containing a binder resin composed of a water-soluble resin, an intermediate layer 3 composed of an aqueous coating layer, and a dye receiving layer 4.

In the present invention, a paper mainly composed of pulp which is generally used can be used as the substrate 1.
Examples of the paper mainly composed of pulp include fine paper, art paper, lightweight coated paper, lightly coated paper, coated paper, cast coated paper, synthetic resin impregnated paper, synthetic resin internal paper, and thermal transfer paper. .

The thickness of the substrate 1 is suitably from 40 to 300 μm, preferably from 60 to 200 μm. If the obtained thermal transfer image-receiving sheet has a texture like a silver halide photograph, the thickness of the thermal transfer image-receiving sheet is desirably 150 to 250 μm.

Using a binder resin for binding the hollow particles and a coating liquid in which the hollow particles are dissolved and dispersed in a solvent, a porous layer containing the hollow particles and the binder resin for binding the hollow particles is formed on the substrate 1. Form 2

The hollow particles used are not limited to expanded particles, non-expanded particles, etc., and may be either closed or continuous expanded. The porosity of the hollow particles is desirably 50% or more.
If the porosity of the hollow particles is 50% or less, the heat insulating property and the cushioning property are insufficient, and the porous layer does not perform its original function.

The content ratio of the hollow particles in the porous layer comprising the hollow particles and the binder resin for binding the hollow particles is preferably 70% by weight or more and 90% by weight or less.

If the binder resin for binding the hollow particles is set to 30% or more, the voids are filled with the resin for binding the hollow particles, and the heat insulation and cushioning properties of the porous layer are lost. Conversely, 10% of resin binds hollow particles
Below this, the strength of the porous layer is weak, and the porous layer peels off from the substrate.

Next, the thickness of the porous layer 2 is preferably 20 to 80 μm. If the thickness is less than 20 μm, sufficient heat insulating properties and cushioning properties cannot be obtained, and print omission occurs during image formation. Further, density unevenness occurs due to unevenness of paper formation, and a high-quality image cannot be obtained. Since the heat insulation effect reaches a saturation level at about 80 μm, making it thicker is disadvantageous in cost.

The resin for binding the hollow particles is preferably an organic solvent-resistant resin. However, acrylic emulsion,
When an emulsion such as a urethane-based emulsion or a polyester-based emulsion is applied to the substrate 1 as a porous layer solution, the water retention of the porous layer solution is poor, so that water permeates into the substrate 1 quickly, and after drying, the porous The surface of the layer 2 becomes uneven, which results in an image with many print omissions, which is not preferable.

Water-soluble resins such as polyvinyl alcohol, sodium polyacrylate, carboxymethyl cellulose, etc.
Since it has a high viscosity and has water retention, it plays a role of a surface sizing agent and delays the penetration of water into the substrate 1. Therefore, after drying, no irregularities are generated on the surface of the porous layer 2, and the image is not printed during image formation. A high quality thermal transfer image-receiving sheet is obtained.

Among the water-soluble resins, a high molecular weight polyvinyl alcohol is particularly preferred because it has a strong binding force to the hollow particles and a high water retention.

The coating of the porous layer 2 is performed by a general method such as gravure coating, gravure reverse coating, comma coating, die coating, and lip coating.

After the application of the porous layer 2, a calendering treatment may be performed to make the surface of the porous layer 2 smoother.

In the present invention, the intermediate layer 3 is formed by an aqueous coating solution. The intermediate layer 3 functions as a solvent barrier layer for preventing the organic solvent in the dye receiving layer 4 from eroding and destroying the hollow particles in the porous layer 2. The aqueous coating liquid refers to an aqueous solution of a water-soluble resin, a dispersion of the resin, or an emulsion of the resin.

Specifically, a urethane resin, a vinyl acetate resin, an acrylic resin and a copolymer thereof, or a resin obtained by blending them are dissolved, dispersed or emulsified in water to form an emulsion. These are used as liquids, and these are applied and dried on the porous layer 2 by each coating method to form the intermediate layer 3. Particularly, a urethane resin blended with polyvinyl alcohol having an average degree of polymerization of at least 1,000 and a saponification ratio of at least 85 mol% to at most 98 mol% is desirable because of its excellent solvent resistance and adhesion to the dye-receiving layer. If the saponification degree is less than 85 mol%, the solvent resistance of the intermediate layer is poor and the solvent is lost during the coating of the receptive layer, which is not preferable. On the other hand, polyvinyl alcohol having a saponification degree of 98 mol% or more, which is generally called a complete saponification type, is excellent in solvent resistance but is not preferable because repelling occurs during coating.

The coating amount of the intermediate layer 3 is preferably in the range of ^{2 to} 15 g / m ² . When the amount is less than 2 g / m ² , the porous layer cannot be completely protected, and the organic solvent in the dye receiving layer 4 erodes the porous layer, so that the function of the intermediate layer 3 cannot be performed. On the other hand, if it is 15 g / m ² or less, the heat insulating and cushioning effects of the porous layer 2 cannot be exhibited, which is not preferable.

In the intermediate layer 3 or the porous layer 2, calcium carbonate, talc, kaolin, titanium oxide, oxidized oxide, etc. may be used as inorganic pigments in order to impart hiding properties and whiteness and to adjust the texture of the thermal transfer image-receiving sheet. Zinc and other known inorganic pigments and fluorescent whitening agents may be included. The compounding ratio is preferably from 10 to 200 parts by weight based on 100 parts by weight of the resin solid content. If the amount is less than 10 parts by weight, the effect is poor. If the amount is more than 200 parts by weight, dispersion stability may be lacking, and the performance of the resin may not be obtained.

An antifoaming agent and a wetting improving agent may be added to the solution of the porous layer 2 and the solution of the intermediate layer 3.

The dye receiving layer is formed by adding various additives such as a releasing agent to a varnish mainly composed of a resin which can easily dye a dye, if necessary. Resins that easily dye dyes include polyolefin resins such as polypropylene, polyvinyl chloride resins, halogenated resins such as polyvinylidene chloride, polyvinyl acetates, and vinyl resins such as polyacrylates.
And copolymers thereof, polyethylene terephthalate, polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymers of olefins such as ethylene and propylene with other vinyl monomers, ionomers, simple substances of cellulose derivatives, Alternatively, a mixture can be used, and among these, a polyester-based resin and a vinyl-based resin are preferable.

The dye receiving layer 4 may contain a release agent to prevent thermal fusion with the thermal transfer sheet during image formation. As the release agent, silicone oil or a phosphate ester plasticizer fluorine compound can be used, but silicone oil is particularly preferable. As silicone oil,
Epoxy-modified silicone, alkyl-modified silicone, amino-modified silicone, fluorine-modified silicone, phenyl-modified silicone, epoxy / polyether-modified silicone, and other modified silicones such as polyether-modified silicones are preferably used. A reaction product with a modified silicone oil is preferred. The amount of the release agent to be added is preferably 0.2 to 30 parts by weight based on the resin for forming the dye receiving layer.

The dye receiving layer 4 is formed by a general method such as roll coating, bar coating, gravure coating, gravure reverse coating and the like. The coating amount of the dye receiving layer 4 is 0.5 to
10 g / m ² is preferred.

When a substrate such as the present invention is used, if a plurality of resin layers are formed and the substrate such as coated paper is exposed as it is on the back surface side, thermal transfer image receiving due to environmental temperature and humidity may occur. The sheet may curl. Therefore, it is preferable to form an anti-curl layer mainly composed of a resin having a water retaining effect such as polyvinyl alcohol and polyethylene glycol on the back surface side of the base material.

In addition, a back surface layer having lubricity may be provided on the side opposite to the dye receiving layer 4 of the thermal transfer image receiving sheet according to the transport system of the thermal transfer image receiving sheet of the printer to be used. In order to impart lubricity to the back layer, a resin in which an inorganic or organic filler is dispersed in a resin of the back layer is used. As the resin used for the slippery back layer, a known resin or a resin obtained by blending them can be used. A lubricant or release agent such as silicone may be added to the back surface layer. These back layers are preferably coated at a thickness of 0.05 to 3 g / m ² .

Hereinafter, the present invention will be described more specifically with reference to Examples.

(Example 1) As a substrate, a basis weight of 209 g / m
^2. Coated paper (Nippon Kaishi Paper Co., Ltd., NK High Coat)
It was used.

A porous layer having the following composition (hollow particles: binder resin = 9: 1 (solid content ratio)) is applied to a substrate by gravure coating at a thickness of 40 μm, and then dried at 110 ° C. for 1 minute to form a porous layer. did. Composition of coating liquid for porous layer: 100 parts by weight of acrylic hollow particles (manufactured by Rohm Ant Haas Co., Ltd., Rohike HP-1055) 19 parts by weight of a 15% solution of polyvinyl alcohol (average degree of polymerization 1000) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) , KH-11) 40 parts by weight of water

Next, an intermediate layer having the following composition was coated on the porous layer by gravure coating at 4 g / m ^{2 and} dried at 110 ° C. for 1 minute to obtain an intermediate layer. Composition of coating solution for intermediate layer: 50 parts by weight of polyester urethane (AP-40, manufactured by Dainippon Ink and Chemicals, Inc.) 33 parts by weight of 15% polyvinyl alcohol solution (88% saponification degree) (Nippon Synthetic Chemical Industry Co., Ltd.) GL-05) Water / isopropyl alcohol = 1/1 30 parts by weight

Next, a dye receiving layer having the following composition was coated on the intermediate layer by a gravure coater at 4 g / m ^{2 and} dried at 110 ° C. for 1 minute to obtain a dye receiving layer. Composition of coating solution for dye receiving layer: 100 parts by weight of vinyl chloride-vinyl acetate copolymer (# 1000A, manufactured by Denki Kagaku Kogyo KK) 5 weights of amino-modified silicone (X22-3050C, manufactured by Shin-Etsu Chemical Co., Ltd.) Part Epoxy-modified silicone (X22-3000E, manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts by weight Methyl ethyl ketone / toluene = 1/1 400 parts by weight

A back layer having the following composition was coated on the side of the substrate on which the dye receiving layer was not formed by a gravure coater at 0.05 g / m ² , dried at 110 ° C. for 1 minute, and the thermal transfer image-receiving sheet of Example 1 was obtained. Obtained. Composition of backside layer coating liquid: 1 part by weight of polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) 100 parts by weight of water

Example 2 A thermal transfer image-receiving sheet of Example 2 was obtained in the same manner as in Example 1, except that the porous layer was changed to the following composition (hollow particles: binder = 8: 2 (solid content ratio)). . Composition of porous layer: acrylic hollow particles 100 parts by weight (Rohm and Haas Co., Ltd., Robake HP-1055) Polyvinyl alcohol 15% solution 44 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM-11) Water 40 parts by weight

Example 3 A thermal transfer image-receiving sheet of Example 3 was obtained in the same manner as in Example 1 except that the porous layer was changed to the following composition (hollow particles: binder = 7: 3 (solid content ratio)). . Composition of porous layer: acrylic hollow particles 100 parts by weight (Rohm and Haas Co., Ltd., Robake HP-1055) Polyvinyl alcohol 15% solution 76 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM-11) Water 40 parts by weight

Example 4 A thermal transfer image-receiving sheet of Example 4 was obtained in the same manner as in Example 1 except that the degree of saponification of PVA used for the intermediate layer was changed to 97 mol%. Composition of the intermediate layer: 50 parts by weight of polyester urethane (AP-40, manufactured by Dainippon Ink and Chemicals, Inc.) 33 parts by weight of a 15% polyvinyl alcohol solution (97% saponification degree) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) P-610) Water / isopropyl alcohol = 1/1 30 parts by weight

Comparative Example 1 The composition of the porous layer of Example 1 was
The composition (hollow particles: binder = 6: 4 (solid content ratio))
The heat transfer of Comparative Example 1 was performed in the same manner as in Example 1 except that
A copy sheet was obtained. Composition of porous layer: Acrylic hollow particles 100 parts by weight (Rohm and Haas Co., Ltd., Robake HP-1055) Polyvinyl alcohol 15% solution 117 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM-11) Water 60 parts by weight

Comparative Example 2 The composition of the porous layer of Example 1 was
The composition (hollow particles: binder = 5: 5 (solid content ratio))
The heat transfer of Comparative Example 2 was performed in the same manner as in Example 1 except that
A copy sheet was obtained. Composition of porous layer: Acrylic hollow particles 100 parts by weight (Rohm and Haas Co., Ltd., Robake HP-1055) Polyvinyl alcohol 15% solution 176 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM-11) Water 60 parts by weight

Comparative Example 3 The composition of the porous layer of Example 1 was as follows:
The composition (hollow particles: binder = 4: 6 (solid content ratio))
The heat transfer of Comparative Example 3 was performed in the same manner as in Example 1 except that
A copy sheet was obtained. Composition of porous layer: Acrylic hollow particles 100 parts by weight (Rohm and Haas Co., Ltd., Robake HP-1055) Polyvinyl alcohol 15% solution 265 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM-11) Water 80 parts by weight

Comparative Example 4 The binder resin in the porous layer of Example 1 was sodium polyacrylate (average molecular weight 500,000)
A thermal transfer image-receiving sheet of Comparative Example 4 was obtained in the same manner as in Example 1 except for changing to. Composition of coating liquid for porous layer: 100 parts by weight of acrylic hollow particles (Rohant HP-1055, manufactured by Rohm Ant Haas) 17 parts by weight of sodium polyacrylate solution (A-20L, manufactured by Toagosei Co., Ltd.) 17 parts by weight of water 40 parts by weight Department

Comparative Example 5 The thermal transfer image-receiving sheet of Comparative Example 5 was produced in the same manner as in Example 1 except that the binder resin in the porous layer of Example 1 was changed to low polymerization degree polyvinyl alcohol (average degree of polymerization: 500). I got

Comparative Example 6 A thermal transfer image-receiving sheet of Comparative Example 6 was obtained in the same manner as in Example 1 except that the binder resin in the porous layer of Example 1 was changed to an acrylic emulsion.

(Comparative Example 7) The thickness of the porous layer of Example 1 was 1
A thermal transfer image-receiving sheet of Comparative Example 7 was obtained in the same manner as in Example 1 except that the thickness was changed to 5 μm.

Comparative Example 8 A thermal transfer image-receiving sheet of Comparative Example 8 was obtained in the same manner as in Example 1, except that the degree of saponification of PVA used for the intermediate layer was changed to 77%. Composition of the intermediate layer: polyester urethane 50 parts by weight (Dainippon Ink & Chemicals, Inc., AP-40) Polyvinyl alcohol 15% solution (saponification degree 77%) 33 parts by weight (Nippon Synthetic Chemical Industry Co., Ltd., KM- 11) Water / isopropyl alcohol = 1/1 30 parts by weight

(Evaluation) The following evaluation was performed using the obtained thermal transfer image-receiving sheet. 1. The surface smoothness of the porous layer was visually evaluated. 2. The hollow particle binding force of the binder resin was evaluated by tape peeling. 3. Density unevenness was printed by printing black gradation and evaluated visually. 4. The images were visually evaluated for the degree of missing prints. The results are shown in Table 1 below. In addition, in the table, regarding the porous layer surface smoothness, 「indicates“ surface smoothness is high ”,
× indicates that “the surface has irregularities and is in the form of citrus skin”;
Indicates that the surface is low in smoothness but no noticeable unevenness is observed, and regarding the hollow particle binding force, は indicates `` no problem in binding force '', and x indicates `` peeled and unusable ''. Regarding density unevenness, ○ indicates “no density unevenness”,
× indicates “density unevenness”, regarding the image, ○ indicates “no missing printing”, x indicates “missing printing”, and Δ
Indicates that "a slight omission of printing is recognized, but no remarkable omission of printing."

[0056]

[Table 1]

In Examples 1 to 4 in which polyvinyl alcohol was used as the binder resin for the porous layer, there was no problem regarding the surface smoothness of the porous layer and the binding force of the hollow particles, and no unevenness in the density of the transferred image was observed. Good results were obtained without any omission of images. (Comprehensive evaluation: ○)

In Comparative Example 1 in which the composition of the porous layer of Example 1 was changed to the following composition (hollow particles: binder = 6: 4 (solid content ratio)), the surface smoothness was low, and some printing defects were observed. Was. (Comprehensive evaluation: ×)

In Comparative Example 2 in which the composition of the porous layer in Example 1 was changed to the following composition (hollow particles: binder = 5: 5 (solid content ratio)), there were surface irregularities, and slight printing omission was observed. Was. (Comprehensive evaluation: ×)

In Comparative Example 3 in which the composition of the porous layer in Example 1 was changed to the following composition (hollow particles: binder = 4: 6 (solid content ratio)), there were surface irregularities and omission of printing was observed. . (Comprehensive evaluation: ×)

Comparative Example 4 in which the binder resin in the porous layer of Example 1 was changed to sodium polyacrylate (average molecular weight: 500,000). In Comparative Example 5 in which the binder resin in the porous layer of Example 1 was changed to 500) and in Comparative Example 6 in which the binder resin in the porous layer was changed to an acrylic emulsion, the adhesive strength of the hollow particles was inferior and the hollow particles were peeled off. Further, in Comparative Example 6, printing omission was slightly observed.
(Comprehensive evaluation: ×)

In Comparative Example 7 in which the porous layer of Example 1 was changed to 15 μm, the surface smoothness was low, and unevenness in density and missing prints were observed. (Comprehensive evaluation: ×)

In Comparative Example 8 in which the saponification degree of PVA used for the intermediate layer was changed to 77%, unevenness in density and print omission were observed. (Comprehensive evaluation: ×)

[0064]

The thermal transfer image-receiving sheet of the present invention is characterized in that a water-permeable resin having high water retention functioning as a sizing agent is used as a binder resin for the porous layer to reduce the rate of water penetration into the base paper. The surface of the porous layer can be smoothed. Above all, by using high-molecular-weight polyvinyl alcohol, the excellent hollow particle binding force is maintained even if the amount of the binder resin is small, and as a result, the heat insulating property, the cushioning property, the sensitivity is high, and the printing quality is high without any omission. A thermal transfer image receiving sheet can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a thermal transfer image receiving sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Porous layer 3 Intermediate layer 4 Dye receiving layer

Continuation of front page (72) Inventor Shinji Yoneya 1-1-1 Ichigaya-Kagacho, Shinjuku-ku, Tokyo F-term (reference) in Dai Nippon Printing Co., Ltd. 2H111 AA14 AA27 CA03 CA04 CA23 CA30 CA41 CA45

Claims (6)

[Claims] 1. A thermal transfer image-receiving sheet comprising a cellulose-based paper as a substrate and a porous layer containing hollow particles, an intermediate layer and a dye-receiving layer formed on the substrate in this order. Wherein the resin for binding the hollow particles is a water-soluble resin. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the content ratio of the hollow particles in the porous layer is from 70% by weight to 90% by weight. 3. The thermal transfer image-receiving sheet according to claim 1, wherein the resin binding the hollow particles in the porous layer is a polyvinyl alcohol resin having an average degree of polymerization of 1000 or more. 4. The thermal transfer image receiving sheet according to claim 1, wherein said porous layer has a thickness of 20 to 80 μm. 5. The thermal transfer image-receiving sheet according to claim 1, wherein polyvinyl alcohol is copolymerized or blended with the resin of the intermediate layer. 6. The intermediate layer according to claim 5, wherein said saponification degree is from 85 mol% to 98 mol%.
6. The thermal transfer image-receiving sheet according to claim 5, comprising mol% of a polyvinyl alcohol resin.