JPH09193561A - Thermal transfer image receiving sheet - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: Regarding a thermal transfer image receiving sheet, in addition to the original performance of the image receiving sheet, the back surface has writing aptitude with various writing instruments, stamp adhesion, and releasability, and is also suitable for use as a postcard. In addition, it is possible to provide a thermal transfer image receiving sheet excellent in performance and suitability for use, which prevents the thermal transfer sheet from being fused even if the front and back of the image receiving sheet are erroneously transferred by a printer. SOLUTION: A color material receiving layer 3 is provided on one surface of a base sheet 2.
On the other side with thermoplastic resin and pore volume of 0.2 ~
The thermal transfer image-receiving sheet 1 is constructed by sequentially providing a back surface layer 4 made of 3.0 ml / g of hydrophilic porous microsilica and a release layer 6 made of PVA having a polymerization degree of 500 to 3000 and a saponification degree of 50 to 95%. To do. As the thermoplastic resin, polyvinyl butyral is preferable, and a curing agent such as an isocyanate compound may be added thereto. It is also preferable to add a spherical slip filler having a particle size larger than that of microsilica to the back surface layer 4.

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, and more specifically, a thermal transfer image receiving sheet is superposed on the thermal transfer image receiving sheet.
In a thermal transfer image receiving sheet used to form an image by thermally transferring a color material such as a dye with a thermal head, in addition to the original performance of the thermal transfer image receiving sheet such as printer suitability on the back side, the writing aptitude of various writing instruments and the adhesiveness of stamps are provided. The present invention relates to a thermal transfer image-receiving sheet which can be used in applications such as postcards without any problem by providing an applied back surface layer.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer image-receiving sheet is provided with a coloring material receiving layer for improving the receiving and holding properties of coloring materials such as dyes on the front surface, and at the same time, the back surface thereof is automatically fed by a printer. To improve the transportability of paper, etc., and to prevent the thermal transfer sheet and the image receiving sheet from fusing when the front and back sides of the image receiving sheet are mistakenly inserted into the printer, and also to superimpose the image receiving sheets after printing. When it is stored for a long time, dye etc. migrates to the back side, and the image density on the front side is prevented from decreasing, and the back side is prevented from being contaminated. It has been practiced to provide a backside layer to impart stain resistance.

In recent years, there has been an increasing need to use a thermal transfer image receiving sheet as a postcard such as a postcard, and a color image such as a photograph is thermally transferred onto the front surface of the image receiving sheet, and the back surface has the above-mentioned performance in addition to the above performance. Therefore, it has become necessary to add writing aptitude and adhesiveness of a stamp for writing an address, a sent sentence, and affixing a stamp. As a method for responding to such needs, for example, by adding a hydrophilic filler to the back surface layer to form a porous body, to give the fountain pen or other water-based pen writability and stamp adhesion, or inorganic or organic The hard filler has been added to give pencil writability.

However, by forming a porous body with the usual hydrophilic filler as described above, it is possible to give the writability of an aqueous pen and the adhesiveness of a stamp, or to add a hard inorganic or organic filler to the pencil writability. With such a method, postcard performance having both writability and stamp adhesiveness of a water-based pen and pencil cannot be sufficiently obtained, and on the other hand, by imparting postcard performance, a thermal transfer image-receiving sheet There was also a problem that the original properties such as slipperiness, releasability, and stain resistance on the back surface of the sheet were adversely reduced.

[0005]

As a result of earnest research to solve the above-mentioned problems of the prior art, microsilica produced by a wet method is porous and has a pore volume, and at the same time, especially on the surface thereof. When not treated, since it has a silanol group (-SiOH) which is a hydrophilic functional group on the surface, it is significantly superior in hydrophilicity and water absorption as compared with a normal hydrophilic filler, and the pore volume is Paying attention to the fact that it is sufficiently small and has a hardness sufficient to impart pencil writability if it has a certain volume or less, and the backside layer of the image-receiving sheet has an average particle size of 0.5 to 15 μm and is fine. Pore volume is 0.
Depending on the size of the pore volume of the microsilica, the composition may be formed by using a composition in which a predetermined amount of hydrophilic porous microsilica in the range of 2 to 3.0 ml / g is contained in a thermoplastic resin as a main component. The pore volume for obtaining the writability and adhesiveness of the stamp of the water-based writing instrument is relatively large within the above range, that is, 1.2 to 3. 0 ml / g of hydrophilic porous microsilica and the pore volume for obtaining pencil writability are relatively small within the above range, that is, 0.2 to 0.9 ml / g of hydrophilic porous microsilica. By forming a composition in which silica and a predetermined amount of at least one kind of thermoplastic resin are contained as main components, an image receiving sheet excellent in both writability and stamp adhesion to an aqueous writing instrument, and pencil writability. Can create It came.

Further, as the thermal transfer image-receiving sheet, it is important that the back surface is excellent in the above-mentioned postcard performance, and at the same time, the original performance of the image-receiving sheet such as transportability in a printer and stain resistance to dyes on the back surface. There, from this point, a spherical slip filler having a larger particle size than microsilica to the thermoplastic resin of the back surface layer, for example, a spherical nylon filler is further added to reduce the friction coefficient, and the thermoplastic resin itself, It is preferable to use a resin having low dye-dyeability, and polyvinyl butyral is particularly preferable. When polyvinyl butyral is used, it is also an effective means to further add a curing agent such as an isocyanate compound or a chelating agent to cure the resin.

By constructing the back layer of the image-receiving sheet in this way, it is excellent in writing properties for various writing instruments and adhesiveness to stamps, and is substantially satisfactory in transportability in a printer and stain resistance to dyes on the back face. An image receiving sheet that can be obtained was obtained. However, even with such an image receiving sheet, for example, when the front and back of the image receiving sheet are misused such that they are passed through a printer by mistake, the releasability of the back surface of the image receiving sheet is insufficient, and the transfer sheet is transferred during thermal transfer. The surface of the ink layer and the back surface of the image receiving sheet are heat-fused to each other, which causes a problem that the image receiving sheet cannot be discharged from the printer. Therefore, in order to use the image receiving sheet more safely, it is preferable to improve the releasability of the back surface layer so that the image receiving sheet can be smoothly discharged even by such misuse.

The present invention has been made in order to solve such a problem, and further improves the back surface layer of a thermal transfer image-receiving sheet so that the back surface can be used for various writing instruments such as water-based pens, oil-based pens and pencils. In addition to being excellent in writability and stamp adhesion, transportability in a printer, stain resistance of the back side when image-receiving sheets after printing are superposed and stored, and further,
An object of the present invention is to provide a thermal transfer image-receiving sheet that is excellent in overall performance such as releasability when the front and back of the image-receiving sheet are mistakenly passed through a printer.

[0009]

The above problems can be solved by the present invention described below. That is, the invention according to claim 1 is a thermal transfer image-receiving sheet in which a color material receiving layer is laminated on one surface of a substrate sheet, and a back surface layer and a release layer are sequentially laminated on the other surface. The back layer contains a thermoplastic resin and hydrophilic porous microsilica having a pore volume of 0.2 to 3.0 ml / g as main components, and the release layer has a degree of polymerization of 500 to 3000. A thermal transfer image-receiving sheet characterized by being a polyvinyl alcohol having a saponification degree of 50 to 95%.

The invention according to claim 2 is the thermal transfer image-receiving sheet according to claim 1, wherein the thermoplastic resin of the back surface layer is polyvinyl butyral. The invention according to claim 3 is the thermal transfer image-receiving sheet according to claim 1 or 2, wherein the back surface layer further contains an isocyanate compound or a chelating agent.

According to a fourth aspect of the present invention, the average particle size of the microsilica contained in the back surface layer is 1 to 5 μm.
The thermal transfer image receiving sheet according to any one of claims 1 to 3, wherein

According to a fifth aspect of the present invention, the microsilica contained in the back surface layer is composed of at least two kinds of microsilica having different pore volumes, and the pore volumes of 0.2 to 0. 9. At least one kind of hydrophilic porous microsilica of 9 ml / g and hydrophilic porous microsilica of pore volume 1.2 to 3.0 ml / g are contained, respectively. The thermal transfer image-receiving sheet as described in any of 1 to 4.

According to a sixth aspect of the present invention, the backside layer has a microsilica / thermoplastic resin ratio of 0.1 to 0.1.
The thermal transfer image-receiving sheet according to claim 1, wherein the thermal transfer image-receiving sheet is 3.0. In the invention according to claim 7, the back surface layer further has an average particle size of 5
The thermal transfer image-receiving sheet according to any one of claims 1 to 6, which contains a spherical nylon filler having a diameter of -15 µm. The invention according to claim 8 is the thermal transfer image-receiving sheet according to any one of claims 1 to 7, wherein the release layer has a thickness of 0.01 to 1.0 µm. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the material and processing method of the thermal transfer image-receiving sheet of the present invention will be described. (Substrate sheet) The substrate sheet used for the thermal transfer image-receiving sheet of the present invention holds the coloring material receiving layer and the back surface layer, and heat is applied during thermal transfer, so that there is no problem in handling even in a heated state. It is preferable to have a mechanical strength of. Further, when the image receiving sheet is used as a postcard, it is necessary to have a rigidity suitable for this. Therefore, it is not particularly limited as long as it has such performance, and for example, paper such as high-quality paper, art paper, coated paper, cast coated paper, postcard paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex. In addition to impregnated paper, synthetic resin internal paper, processed paper such as various plastic laminated paper, and polyolefin-based paper,
Alternatively, synthetic paper such as polystyrene, polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer,
Polypropylene, polystyrene, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride Films or sheets of various plastics such as, tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, polychlorotrifluoroethylene, and polyvinylidene fluoride can be used, and white pigments for these plastics can be used. Alternatively, a white opaque film formed by adding a filler, or a foamed foamed sheet can be used.

Further, a laminated body made of any combination of the above-mentioned substrate sheets can also be used. As a typical example of a combination of laminated bodies, a laminated body of cellulose fiber paper and synthetic paper, a laminated body of cellulose fiber paper and a plastic film or sheet, a laminated body of different types or grades of plastic films or sheets, and the like. Is mentioned. Although such a laminated body may be a two-layered body, coated paper or a white or transparent plastic film is used as a core material in order to give a texture and a texture of a base material, and synthetic paper or a foamed plastic film is laminated on both surfaces thereof. The above-mentioned three-layer body or a laminate of three or more layers can also be used. The thickness of these base material sheets is not particularly limited, but is usually 50 to 800 μm.
A thickness of about m is appropriate. Further, in the case where the substrate sheet as described above has poor adhesion to the layer formed on the surface thereof, the surface thereof can be subjected to corona discharge treatment, plasma treatment, or various primer coats.

(Coloring Material Receiving Layer) In the thermal transfer image-receiving sheet of the present invention, the coloring material receiving layer formed on one surface of the substrate sheet receives a coloring material such as a sublimable dye transferred from the thermal transfer sheet. In order to maintain the formed image, any known material used for a color material receiving layer of a thermal transfer system such as sublimation type thermal transfer containing a dye-dyeing resin as a main component is used. it can. However, it is also necessary to have a mold release property to the extent that thermal fusion with the thermal transfer sheet is prevented, and a dye-permeable mold release agent may be contained or a mold release layer may be provided on the receiving layer. In addition, various additives such as pigments may be added. The coating amount of the colorant receiving layer is usually suitable in the range of about 2.5 to 5.0 g / m ² in terms of solid content.
In addition, at least one or more intermediate layers may be provided between the coloring material receiving layer and the base sheet. The intermediate layer means an adhesive layer (primer layer), a whitening layer, a barrier layer, a UV (ultraviolet) absorbing layer, a foaming layer, an antistatic layer, and all layers provided between the receiving layer and the base sheet, The known ones are
Either can be used as required.

(Back Layer) The thermal transfer image-receiving sheet of the present invention comprises
It is designed to be used as a picture postcard in addition to the usual image receiving sheet.
At least the back surface layer and the release layer are sequentially stacked, and each has its own characteristics. The backside layer is particularly suitable for any writing instruments such as pencils and mechanical pencils that are commonly used writing instruments, fountain pens, water-based writing instruments such as water-based pens, and oil-based writing instruments such as ballpoint pens and oil-based pens. Also has excellent writing aptitude and adhesiveness of stamps, and even if the image recording surface and the back surface of the image receiving sheet are superposed and stored, the back surface is not contaminated by migration of dye and the like, and the printer. It is configured so as to have an appropriate slip property for improving the transportability in the above.

For this reason, the back surface layer is made of a thermoplastic resin serving as a binder, and a hydrophilic porous microsilica having a pore volume of 0.2 to 3.0 ml / g, which is produced by a wet method of dispersing the thermoplastic resin in the binder. It is composed mainly of and. Although various kinds of thermoplastic resins can be used as the binder thermoplastic resin, in addition to the function as a fixing agent, as described above, it has stain resistance so that the back surface of the image receiving sheet is not contaminated by the dye or the like. Is also required, and a thermoplastic resin having low dye-dyeability is preferable, and polyvinyl butyral is particularly preferable. Further, it is more preferable to add a chelating agent or an isocyanate compound to the polyvinyl butyral to cure it.

Further, the pore volume produced by the wet method is 0.
As the hydrophilic porous microsilica of 2 to 3.0 ml / g, one kind may be used, but as described above,
Micro silica having a pore volume of 0.2 to 0.9 ml / g,
It is more preferable to use at least one kind of microsilica having a pore volume of 1.2 to 3.0 ml / g in combination, because the respective characteristics can be utilized more reliably. That is, 0.2 to 0.9 ml / having a small pore volume
The hydrophilic porous microsilica in the range of g has sufficient hardness for imparting pencil writability, and has hydrophilicity and water absorption superior to those of ordinary hydrophilic fillers. It also contributes to the improvement of the writability of writing instruments and the adhesiveness of stamps. Also, the large pore volume is 1.2 to
The hydrophilic porous microsilica in the range of 3.0 ml / g tends to be slightly inferior to the writability of a pencil because it is slightly decreased in terms of hardness, but it is excellent in hydrophilicity and water absorption, It is particularly effective for improving the writability and adhesiveness of stamps of a water-based writing instrument.

Here, the microsilica will be slightly supplemented. Microsilica is also produced by the dry method, but in the case of the dry method, since silicon tetrachloride is produced by burning and hydrolyzing silicon tetrachloride in the gas phase, the produced microsilica has no voids inside the particles, that is, It is a silica with no internal surface area. Such silica has low water absorption, and is not suitable for the use which requires high hydrophilicity and water absorption as in the present invention. In this respect, microsilica produced by a wet method (gel method) is produced by gelling silica sol produced by the reaction of an aqueous sodium silicate solution with sulfuric acid or hydrochloric acid, and porous silica is obtained. And, since such silica is porous and has a hydrophilic functional group (silanol group) on the surface at the same time, it has higher hydrophilicity and higher water absorption than an ordinary hydrophilic filler, It is suitable for improving the writing property and the adhesiveness of a stamp of a pen. Depending on the application, silica produced by the wet method may also
In some cases, hydrophilicity is not preferable, and there is also silica which has been surface-treated with an organic substance or an inorganic substance in order to reduce hydrophilicity. However, hydrophilicity is important in the present invention, and it is preferable to use untreated silica.

As a parameter showing the porosity of the microsilica, there is a pore volume. Generally, as the pore volume becomes larger, the surface area becomes larger, and the amount of silanol groups per unit volume increases, so that the hydrophilicity and water absorbency are increased. Is higher, and the fixability and adhesiveness of stamps of water-based inks such as fountain pens and water-based pens are improved, but when it exceeds 3.0 ml / g, on the contrary, the hydrophilicity becomes too high and the water-based ink bleeds, When the voids in the microsilica particles become large, the hardness is lowered, which causes a problem such as a reduction in pencil writability, which is not preferable. On the other hand, when the pore volume is less than 0.2 ml / g, the hardness is sufficient and the pencil writability is good, but the hydrophilicity and water absorption are low, and the fixability of water-based ink and the adhesiveness of stamps are reduced. It is not preferable because it causes

The particle size of the above-mentioned micro silica is
Those having an average particle diameter of 0.5 to 15 μm can be used, and those having an average particle diameter of 1 to 5 μm are more preferable. When the average particle size is less than 0.5 μm, the pencil writability becomes insufficient, and when the average particle size exceeds 15 μm, the water-based writing tool tends to bleed, and the friction coefficient of the back surface is low. It is not preferable because it becomes large and transportability is deteriorated.

The amount of microsilica added to the thermoplastic resin is the weight ratio of microsilica / thermoplastic resin,
The range of 0.1 to 3.0 is preferable. The weight ratio is 0.1
If it is less than the above, sufficient writing aptitude and stamp adhesiveness cannot be obtained, and if the weight ratio exceeds 3.0, the coating aptitude is lowered at the same time as the coating aptitude is lowered. However, this is not preferable because it causes problems such as easy peeling of the coating film.

It is also important to improve the transportability of the image-receiving sheet such as paper feeding and discharging in a printer. For this purpose, the back surface layer having the above-mentioned structure is further provided with a spherical smoothness having a particle diameter larger than that of microsilica. It is also effective to prevent multiple insertion by containing a filler to reduce the friction coefficient on the back surface. The average particle size of the spherical lubricous filler is 5 to 15 μm.
The material is preferably spherical nylon filler.

The backside layer as described above has a coating amount of 0.5 to 5.0 in terms of solid content in order to fully exert its performance.
It is preferably g / m ² . Coating amount is 0.5g / m
If it is less than ² , the amount of microsilica is insufficient,
Sufficient writability and stamp adhesion cannot be obtained. Also, 5
A coating amount of more than g / m ² is not necessary, and conversely,
Material and processing costs are also increased, which is not preferable.

The back surface layer may be directly provided on the base material sheet, but if the back surface layer does not have sufficient adhesion to the base material sheet, it may be provided between the base material sheet and the back surface layer. On the other hand, an intermediate layer containing a resin with good adhesiveness as a main component may be provided, and white color such as titanium oxide, calcium carbonate, optical brightener, or other pigments may be added to the intermediate layer as necessary. Agents can also be added. Further, a known intermediate layer used between the base material sheet and the color material receiving layer can be similarly used as it is between the base material sheet and the back surface layer.

(Release Layer) In the present invention, even when the front and back of the thermal transfer image-receiving sheet are mistakenly passed through a printer, the back surface of the image-receiving sheet does not heat-fuse with the ink layer surface of the thermal transfer sheet, and smoothly. A release layer is further laminated on the back surface layer so as to be discharged. Therefore, the release layer does not heat-fuse with the ink layer surface of the thermal transfer sheet, is non-dyeing to a dye, and does not impair postcard aptitude such as writing aptitude or stamp adhesiveness of the back surface layer. It is necessary. To this end, polyvinyl alcohol (hereinafter P
Resins such as cellulose acetate) and 0.01-
It is preferable to stack the layers with a thin film thickness of about 1.0 μm.
When the film thickness is less than 0.01 μm, a sufficient releasing effect cannot be obtained, and when the film thickness exceeds 1.0 μm, sufficient writing aptitude and stamp adhesiveness cannot be obtained, which is not preferable.

The resin for the release layer is, for example, PVA.
Such a hydrophilic resin not only exhibits the above-mentioned performance, but also has the effect of improving the fixability of the water-based ink of a water-based pen or a fountain pen, and is particularly preferable. When PVA is used, if the degree of saponification is too high or the degree of polymerization is too low, the water resistance is reduced, and therefore the back surface layer is peeled off by the water-based ink when writing with a water-based pen or the like. However, if the degree of saponification is too low, sufficient releasability cannot be obtained, and if the degree of polymerization is too high, the coating suitability is reduced, which is not preferable. Therefore, the PVA preferably has a degree of polymerization of 500 to 3000 and a degree of saponification of 50 to 95 mol%.

Each layer of the thermal transfer image-receiving sheet composed of the above-mentioned materials is usually prepared by dissolving or dispersing the material of each of the above layers in a solvent to prepare a coating solution for a substrate sheet and then gravure coating. , Roll coating, blade coating, knife coating, micro bar coating, wire bar coating, spray coating, and the like, each of which is applied and dried in a required amount. The coating method itself is not particularly limited, and any suitable method may be freely selected.

[0030]

The present invention will be described in more detail below with reference to the drawings, examples and comparative examples. 1 and 2 are schematic cross-sectional views each showing the configuration of an embodiment of the thermal transfer image-receiving sheet of the present invention. However, the configuration of the thermal transfer image-receiving sheet of the present invention is not limited to these figures. The same reference numerals are used for the same names in different drawings.

In FIG. 1, a color material receiving layer 3 for receiving a color material such as a dye for forming an image by thermal transfer is laminated on one surface of a base sheet 2, and the other surface has a printer suitability, The back surface layer 4 for imparting stain resistance, writing property, stamp adhesion, and the like, and the performance of the back surface layer 4 are maintained, and even when the front and back surfaces of the image receiving sheet are erroneously heat-transferred by a printer, 1 shows a thermal transfer image-receiving sheet 1 having a structure in which a back surface and a release layer 6 for imparting releasability so as not to be fused to the back surface are sequentially laminated.

FIG. 2 shows that in the case of the thermal transfer image receiving sheet 1 of FIG. 1, the color material receiving layer 3 or the back surface layer 4 is directly provided on the base material sheet 2.
On the other hand, the coloring material receiving layer 3 is laminated on one surface of the base material sheet 2 via the intermediate layer 5a, and the other surface is separated from the back surface layer 4 via the intermediate layer 5b. 1 shows a thermal transfer image-receiving sheet 1 having a structure in which layers 6 are sequentially laminated. The intermediate layers 5a and 5b are used for the purpose of improving the adhesiveness between the base material sheet 2 and the color material receiving layer 3 or the base material sheet 2 and the back surface layer 4, improving the whiteness, etc. It is to be provided.

Example 1 A substrate sheet having a thickness of 15
Using 0 μm synthetic paper [YUPO FPG # 150 manufactured by Oji Yuka Synthetic Paper], one side thereof was coated with a back layer coating solution and a release layer coating solution each having a coating amount of 2.0 g. / M ² (solid content) and 0.1 g / m ² (solid content)
After coating with a roll coat method and drying so that
4. On the other surface, a coating solution for the surface side intermediate layer and a coating solution for the colorant receiving layer having the following compositions were successively applied in the same manner as described above, and the coating amounts were 2.0 g / m ² (solid content) and 5. The thermal transfer image-receiving sheet of Example 1 was prepared by applying the coating solution so that the coating amount was 0 g / m ² and drying. Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Back surface layer (2.0 g / m ² ) / release layer (0.1 g / m ² ).

Composition of coating liquid for back layer Polyurethane [HMS-20 made by Nippon Polyurethane Industry] 50 parts by weight Micro silica [Sylysia 550 manufactured by Fuji Silysia Chemical] 50 parts by weight Solvent (toluene / isopropyl alcohol weight ratio 1: 1) 400 parts by weight Parts (Hereinafter, isopropyl alcohol is indicated as IPA.) Composition of coating liquid for release layer PVA (Gothenol GH-20 manufactured by Nippon Synthetic Chemical Industry) 3 parts by weight Ion-exchanged water 97 parts by weight

Composition of coating liquid for surface side intermediate layer Polyurethane [N5199 Nippon Polyurethane Industry] 50 parts by weight Titanium oxide [TCA-888 manufactured by Tochem Products] 50 parts by weight Solvent (toluene / methyl ethyl ketone weight ratio 1: 1) 400 parts by weight Parts (Hereinafter, methyl ethyl ketone is referred to as MEK.) Composition of coating liquid for colorant receiving layer Vinyl chloride-vinyl acetate copolymer [# 1000A manufactured by Denki Kagaku Kogyo] 75 parts by weight Polyester [Vylon 600 manufactured by Toyobo] 25 parts by weight Parts Catalyst-curable silicone [X62-1212 manufactured by Shin-Etsu Chemical Co., Ltd.] 6 parts by weight Platinum catalyst [PL-50T manufactured by Shin-Etsu Chemical Co., Ltd.] 3 parts by weight Solvent (toluene / MEK weight ratio 1: 1) 400 parts by weight

(Embodiment 2) In the constitution of the image-receiving sheet of Embodiment 1, the constitution of the base sheet, the front surface side intermediate layer and the color material receiving layer is left as it is, and the back surface side intermediate portion is provided between the base material sheet and the back surface layer. Layers are newly provided and the materials of the back surface layer and the release layer are changed. First, the base material sheet (synthetic paper
(A thickness of 150 μm), one side of which is coated with a coating solution for the backside intermediate layer having the following composition at a coating amount of 1.0 g /
m ² (solid content) is applied and dried to form a back surface side intermediate layer, and then a back surface layer coating solution and a release layer coating solution having the following composition are sequentially formed on the same layer by the same method. The coating amount was 2.0 g / m ² (solid content) and 0.1 g / m ² (solid content), and the coating was dried to laminate the back surface layer and the release layer. Then, on the other surface, in the same manner as in Example 1, a surface side intermediate layer and a color material receiving layer were sequentially laminated to prepare a thermal transfer image receiving sheet of Example 2. Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Backside intermediate layer (1.0 g / m ² ) / backside layer (2.0 g / m ² ).
m ² ) / release layer (0.1 g / m ² ).

Composition of Coating Solution for Back Side Intermediate Layer Polyurethane [N5199 Nippon Polyurethane Industry] 50 parts by weight Titanium oxide [TCA-888 manufactured by Tochem Products] 50 parts by weight Solvent (toluene / MEK weight ratio 1: 1) 400 parts by weight Part Composition of coating liquid for back layer Polyvinyl butyral [# 5000-A manufactured by Denki Kagaku Kogyo] 50 parts by weight Micro silica [Sylysia 550 manufactured by Fuji Silysia Chemical] 50 parts by weight Solvent (toluene / IPA weight ratio 1: 1) 400 parts by weight Composition of coating liquid for release layer PVA (Gohsenol KH-20 manufactured by Nippon Synthetic Chemical Industry) 3 parts by weight Ion-exchanged water 97 parts by weight

(Example 3) In the constitution of the image-receiving sheet of Example 1, the back layer and the release layer coating solution were replaced with a back layer coating solution and a release layer coating solution having the following compositions, and the coating was performed. The amounts are 3.0 g / m ² (solid content) and 0.2 g / m ^2, respectively.
A thermal transfer image-receiving sheet of Example 3 was prepared in the same manner as in Example 1, except that the back surface layer and the release layer were laminated so that the coating solution had a thickness of m ² (solid content). Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Back surface layer (3.0 g / m ² ) / release layer (0.2 g / m ² ).

Composition of coating liquid for back layer Polyvinyl butyral [# 3000-1 manufactured by Denki Kagaku Kogyo] 40 parts by weight Isocyanate compound [Takenate D-160N manufactured by Takeda Pharmaceutical Co., Ltd.] 10 parts by weight micro silica [Sylysia 730 manufactured by Fuji Silysia Chemical] 50 parts by weight Solvent (toluene / IPA weight ratio 1: 1) 400 parts by weight Composition of release layer coating solution PVA (Gohsenol KH-17 manufactured by Nippon Synthetic Chemical Industry) 3 parts by weight Ion exchange water 97 parts by weight

(Example 4) In the constitution of the image-receiving sheet of Example 2, the coating liquid for the back layer and the release layer was replaced with the coating liquid for the back layer and the coating liquid for the release layer having the following compositions, and the coating was performed. The amounts are 2.5 g / m ² (solid content) and 0.2 g / m ^2, respectively.
A thermal transfer image-receiving sheet of Example 4 was prepared in the same manner as in Example 2 except that the back surface layer and the release layer were laminated so that the coating solution had m ² (solid content). Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Back side intermediate layer (1.0 g / m ² ) / back side layer (2.5 g / m ² )
m ² ) / release layer (0.2 g / m ² ).

Composition of Back Layer Coating Liquid Polyvinyl butyral [# 3000-1 manufactured by Denki Kagaku Kogyo] 30 parts by weight Micro silica [Sylysia 730 manufactured by Fuji Silysia Chemical] 60 parts by weight Nylon filler [MW-330 manufactured by Shinto Paint Co., Ltd.] 5 Parts by weight Solvent (toluene / IPA weight ratio 1: 1) 400 parts by weight Composition of release layer coating solution PVA (Gohsenol GH-14 manufactured by Nippon Synthetic Chemical Industry) 3 parts by weight Ion exchange water 97 parts by weight

(Example 5) In the constitution of the image-receiving sheet of Example 1, the back layer coating solution was replaced with a back layer coating solution having the following composition, and the coating amount was 3.5 g / m ² (solid content). All were processed in the same manner as in Example 1 except that the back surface layer was laminated by coating and drying so as to form (4), and a thermal transfer image-receiving sheet of Example 5 was prepared. Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Back surface layer (3.5 g / m ² ) / release layer (0.1 g / m ² ).

Composition of Coating Liquid for Back Layer Polyvinyl butyral [# 5000A manufactured by Denki Kagaku Kogyo] 30 parts by weight Micro silica [Sylysia 730 manufactured by Fuji Silysia Chemical] 60 parts by weight Micro silica [Sylysia 310 manufactured by Fuji Silysia Chemical] 30 parts by weight Chelate Agent [Organix TC-750 manufactured by Matsumoto Pharmaceutical Co., Ltd.] 5 parts by weight Nylon filler [MW-330 manufactured by Shinto Paint Co., Ltd.] 5 parts by weight Solvent (toluene / IPA weight ratio 1: 1) 520 parts by weight

(Comparative Example 1) In the constitution of the image-receiving sheet of Example 1, the coating liquid used for forming the back layer was replaced with the coating liquid for the back layer having the following composition (the coating amount was the same), and the release layer was also used. Comparative Example 1 was processed in the same manner as in Example 1 except that
Was formed. Composition of thermal transfer image-receiving sheet Color material receiving layer (5.0 g / m ² ) / front surface side intermediate layer (2.0
g / m ² ) / Base material sheet (synthetic paper thickness 150 μm) /
Back layer (2.0g / m ² )

Composition of coating liquid for back layer Polyurethane [HMS-20 manufactured by Nippon Polyurethane Industry] 50 parts by weight Calcium carbonate [manufactured by Shiraishi PZ Shiraishi Industry] 50 parts by weight Solvent (toluene / IPA weight ratio 1: 1) 400 parts by weight

In each of the thermal transfer image-receiving sheets of Examples 1 to 5, the pore volume (ml / g) and average particle diameter (μm) of microsilica added to the back surface layer are shown in Table 1 below. The values of the degree of saponification and the degree of polymerization of PVA used for the release layer are shown in Table 2 together.

[0047]

[Table 1]

[0048]

[Table 2]

(Tests and Results) Using each of the thermal transfer image-receiving sheets of Examples 1 to 5 and Comparative Example 1 prepared as described above, the following items were tested, and the results are summarized in Table 3. 1) Writability of the back surface of the image receiving sheet Using the following writing tools, characters were written on the back surface of each thermal transfer image receiving sheet of Examples 1 to 5 and Comparative Examples 1 and 2, and evaluation was performed according to the following criteria. Writing instruments used a) Pencil: Mitsubishi office pencil No.9800 HB [manufactured by Mitsubishi Pencil Co., Ltd.] b) Water-based pen: Pentel Sign Pen Black [Pentel Co., Ltd.]
Made) c) Oil-based pen: Magic ink NO.700 black [made by Teranishi Chemical Co., Ltd.] d) Ballpoint pen: Jimny black [made by Zebra Co., Ltd.] Evaluation criteria ○: Can be written smoothly with sufficient density and bleeding It also has good fixability. Δ: The characters are slightly thin. Or something that is slightly bleeding. ×: After 12 hours of writing, the character disappears with light rubbing with a finger.

2) Adhesiveness of stamps on the back surface of the image-receiving sheet. Apply water to the entire adhesive surface of the Japan Post 50 yen stamp with fingers.
Each of the thermal transfer image-receiving sheets of Examples 1 to 5 and Comparative Example 1 was attached to the back surface and left for 12 hours, and then evaluated according to the following criteria. Evaluation Criteria A: The stamp is not peeled off after 12 hours. X: The stamp is easily peeled off by hand after 12 hours have passed.

3) Dye stain resistance on the back surface of the image receiving sheet A black solid image is printed on the image receiving surface of each of the thermal transfer image receiving sheets of Examples 1 to 5 and Comparative Example 1 using the following thermal transfer sheet and sublimation transfer type printer. , Overlap with the back of each, sandwich both sides with smooth aluminum plates, 2 from the top
After applying a load of 0 gf / cm ² and storing it in a thermo-hygrostat at 40 ° C. and 90% RH for 120 hours, the migration state of the dye to the back surface of each sample was visually evaluated according to the following criteria. Evaluation Criteria ◯: Dye transfer is hardly observed. Δ: Dye migration is slight but practically no problem. X: Transfer of dye is recognized. Thermal transfer sheet: VY-SS30 thermal transfer sheet [Co., Ltd.
Hitachi] Printer: Color video printer VY-P1
[Made by Hitachi, Ltd.]

4) Releasability of the back surface of the image receiving sheet Using the thermal transfer sheet and the printer used in the test of the preceding paragraph, a gray gradation image was printed on the back surface of each thermal transfer image receiving sheet of the sample, The releasability was evaluated by the presence or absence of defective discharge due to heat fusion. Evaluation Criteria ○: The image receiving sheet is not thermally fused to the thermal transfer sheet and is smoothly discharged from the printer. X: The image receiving sheet is heat-fused with the thermal transfer sheet and is not smoothly discharged from the printer.

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[Table 3] Evaluation results As is clear from the evaluation results shown in Table 3 above, the thermal transfer image-receiving sheet of Comparative Example 1 has a writing property, adhesiveness of stamps,
There are problems with both dye stain resistance and releasability,
Not preferred. On the other hand, each of the thermal transfer image-receiving sheets of Examples 1 to 5 is excellent in writing property by various writing tools and adhesiveness of stamps, and is also melted with the thermal transfer sheet in case of misuse such as thermal transfer to the back surface of the image-receiving sheet. It was discharged smoothly from the printer without wearing it, and had good release properties. The stain resistance of the dye was also good, with almost no transfer of the dye being observed, or even a slight transfer would cause no problem in practical use.

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As described in detail above, according to the present invention, since the back surface of the image receiving sheet has excellent writing suitability for various writing instruments and adhesiveness with stamps, the image receiving sheet can be used as a postcard without any problem. In addition, the image receiving sheet has good transportability in automatic paper feeding / discharging of a thermal transfer printer, etc., and even if the image receiving sheets after image formation are piled up and stored, the density of the printed image is reduced and the dye on the back surface is dyed. There is no contamination due to the transfer of the image receiving sheet, and even if the front and back of the image receiving sheet are printed by a printer by mistake, the back surface has excellent releasability, so the thermal transfer sheet and the image receiving sheet do not heat-seal and smoothly from the printer. Performance of being discharged,
The effect is that a thermal transfer image-receiving sheet excellent in usability can be provided.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing the configuration of another embodiment of the thermal transfer image receiving sheet of the present invention.

[Explanation of symbols]

 1 Thermal Transfer Image Receiving Sheet 2 Base Material Sheet 3 Coloring Material Receiving Layer 4 Back Layer 5a, 5b Intermediate Layer 6 Release Layer

Claims (8)

[Claims] 1. A thermal transfer image-receiving sheet comprising a base material sheet and a coloring material receiving layer laminated on one surface thereof, and a back surface layer and a release layer laminated on the other surface of the base material sheet in that order. It contains a resin and hydrophilic porous microsilica having a pore volume of 0.2 to 3.0 ml / g as main components, and the release layer has a degree of polymerization of 500 to 3000 and a degree of saponification of 50 to 95%. 1. A thermal transfer image-receiving sheet characterized in that it is a polyvinyl alcohol. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the thermoplastic resin of the back surface layer is polyvinyl butyral. 3. The thermal transfer image-receiving sheet according to claim 1, wherein the back surface layer further contains an isocyanate compound or a chelating agent. 4. The thermal transfer image-receiving sheet according to claim 1, wherein the average particle diameter of the microsilica contained in the back surface layer is 1 to 5 μm. 5. The microsilica contained in the back surface layer is composed of at least two kinds of microsilica having different pore volumes, and the pore volume is 0.2 to 0.9 ml / g.
Of hydrophilic porous microsilica and pore volume of 1.2 to
5. The thermal transfer image-receiving sheet according to claim 1, wherein at least one kind of 3.0 ml / g of hydrophilic porous microsilica is contained. 6. The thermal transfer image-receiving sheet according to claim 1, wherein the backside layer has a microsilica / thermoplastic resin ratio of 0.1 to 3.0 by weight. 7. The back surface layer further has an average particle size of 5 to 1
7. The thermal transfer image-receiving sheet according to claim 1, which contains a spherical nylon filler having a diameter of 5 μm. 8. The thickness of the release layer is 0.01 to 1.0 μm.
The thermal transfer image-receiving sheet according to any one of claims 1 to 7, wherein m is m.