JP2009078387A - Heat transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat transfer image receiving sheet which has a high whiteness of an image receiving face and a high clarity of an image, can obtain an image with a high density and a high resolution, and has a smoothness and feeling of quality equal to a printing paper reproducible of a full color silver salt photograph in a heat transfer image-formed article obtained. <P>SOLUTION: The heat transfer image receiving sheet in which a substrate sheet is prepared by providing polyolefin resin layers on both sides of a core material made of a paper, and the substrate sheet and a porous film are stuck together with an adhesive layer and a dye receiving layer is provided on the porous film through a primer layer, is characterized in that the whiteness of the dye receiving layer side of the substrate sheet is ≥95%. The heat transfer image receiving sheet improves the whiteness of the image receiving face by making the most of the whiteness of the dye receiving layer side of the substrate sheet itself. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer image-receiving sheet provided with a dye-receiving layer on a substrate sheet, and particularly in the obtained thermal transfer image formed product, the image receiving surface has high whiteness, high image clarity, and high density and high resolution. And a thermal transfer image receiving sheet having the same smoothness and texture as a photographic paper that reproduces a full-color silver salt photograph.

  Conventionally, among various thermal transfer recording systems, a thermal sublimation transfer system and a thermal fusion transfer system have been widely used. Among these, the heat-sensitive sublimation transfer method uses a sublimation dye as a color material, and uses a heating device such as a thermal head that controls heat generation according to image information, using a sublimation dye layer formed on a thermal transfer sheet. The dye inside is transferred to the thermal transfer image-receiving sheet to form an image.

  According to this heat-sensitive sublimation transfer method, the amount of dye transfer can be controlled in dot units by heating for an extremely short time. In addition, since the coloring material is a dye, it also has excellent transparency, and the formed image is very clear and at the same time has excellent halftone reproducibility and gradation, so it has extremely high definition. A high-quality image comparable to a full-color silver salt photograph can be obtained.

  As a heat transfer image-receiving sheet for sublimation transfer (hereinafter referred to as an image-receiving sheet) used in such a heat-sensitive sublimation type transfer system, a sheet in which a color material receiving layer is formed on a base sheet is generally used. . Needless to say, this image-receiving sheet has improved whiteness of the image-receiving surface, excellent image sharpness, no density unevenness or missing dots, and high-density, high-resolution images can be obtained. A high degree of smoothness, texture and the like are required. Therefore, as an intermediate layer for improving whiteness between the base sheet of the thermal transfer image-receiving sheet and the dye-receiving layer, for example, as described in Patent Document 1, a white pigment such as titanium oxide or fluorescent material is used for the intermediate layer. It has been shown to contain a brightener.

  In Patent Documents 2 and 3, a thermal transfer image receiving sheet in which a dye receiving layer is provided on the base sheet using a base sheet of the image receiving sheet having a high whiteness, the image receiving surface has whiteness. It has been shown to increase. However, when providing the intermediate layer as described in Patent Document 1, increasing the content of the white pigment to be added in order to increase the whiteness, the adhesiveness between the base sheet and the dye receiving layer is reduced, Further, when the thickness of the intermediate layer is increased, problems such as a decrease in smoothness of the image receiving surface are likely to occur. Further, when the whiteness of the base sheet of the image receiving sheet is increased as in Patent Documents 2 and 3, it is possible to increase the whiteness of the image receiving surface, but in the thermal transfer image formed product, an image with high print density and resolution. Is obtained, but has not yet reached a level having the same smoothness and texture as photographic paper that reproduces a full-color silver salt photograph.

JP-A-6-115260 Japanese Patent Laid-Open No. 2-150389 JP-A-4-28593

  Therefore, the present invention has been made in view of such circumstances, and in the obtained thermal transfer image formed product, the image receiving surface has high whiteness, high image sharpness, and a high-density, high-resolution image. It is an object of the present invention to provide a thermal transfer image-receiving sheet having the same smoothness and texture as a photographic paper reproducing a full-color silver salt photograph.

  The thermal transfer image-receiving sheet of the present invention is as claimed in claim 1, wherein a paper sheet is provided with a polyolefin resin layer on both sides of a base material sheet, and the base material sheet and the porous film are bonded together with an adhesive layer. In the thermal transfer image-receiving sheet in which the dye-receiving layer is provided on the porous film via the primer layer, the whiteness of the base sheet on the dye-receiving layer side is 95% or more. The above-described thermal transfer image-receiving sheet is one in which the whiteness of the image-receiving surface is enhanced by taking advantage of the whiteness of the substrate sheet itself on the dye-receiving layer side.

  High adhesion between the porous film and the dye-receiving layer, high image clarity, high density and high resolution images, smoothness and texture equivalent to photographic paper that reproduces full-color silver salt photographs And the like. Moreover, since the whiteness degree of the said base material sheet at the dye receiving layer side is 95% or more, the thing with higher whiteness of an image receiving surface and a clearer image is obtained.

  The thermal transfer image-receiving sheet of the present invention has a high whiteness on the image-receiving surface, a high image sharpness, a high-density and high-resolution image, and reproduces a full-color silver salt photograph in the resulting thermal transfer image-formed product. It has the same smoothness and texture as photographic paper.

  FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermal transfer image-receiving sheet 1 of the present invention. A polyolefin resin layer 1 (8) and a polyolefin resin layer 2 (9) are provided on both sides of a paper core material 7. In the base sheet 2, an adhesive layer 5, a porous film 3, a primer layer 6, and a dye receiving layer 4 are sequentially formed on the polyolefin resin layer 1, and opposite to the dye receiving layer side of the base sheet 2. The back layer 10 is provided on the side. In this case, the back surface layer 10 and the polyolefin resin layer 2 are in contact with each other. The back layer is provided in order to improve transportability in a printer or the like, or to prevent charging, but can be omitted as appropriate.

Hereinafter, each layer constituting the thermal transfer image receiving sheet of the present invention will be described in detail.
(Substrate sheet)
The base sheet 2 of the thermal transfer image receiving sheet used in the present invention is one in which polyolefin resin layers 1 and 2 (8, 9) are provided on both sides of a core material 7 made of paper. Since the base sheet has a role of holding the dye-receiving layer and heat is applied during thermal transfer, the base sheet preferably has a mechanical strength that does not hinder handling even in a heated state.

  As the core material 7 made of paper, uncoated paper mainly composed of commonly used pulp is used. Examples thereof include base paper, fine paper, and the like. Specifically, a pulp paper material obtained by beating desired pulp, in particular, a base paper obtained by making a pulp slurry beaten and adjusted, is used. The pulp is not particularly limited, and natural pulp selected from conifers, hardwoods, etc., for example, LBKP (hardwood bleached kraft pulp) such as aspen, acacia, maple, poplar, eucalyptus, spruce, Douglas fir NBKP (coniferous tree bleached kraft pulp) such as wood, LBSP, NBSP, LDP, NDP, LUKP, NUKP and the like can be selected as appropriate. These can be used alone or in combination of two or more, in addition to being used alone. As the pulp, it is preferable to use a pulp having few impurities, and it is preferable to use a pulp (bleached pulp) which has been subjected to a bleaching treatment to improve whiteness.

  Among the above, the pulp is preferably a hardwood bleached kraft pulp (bleached LBKP) that has been bleached to improve whiteness in terms of impurities and hue, and among them, aspen, acacia, maple, and poplar Hardwood bleached kraft pulp (bleached LBKP) comprising at least one selected from the above is particularly preferred. Each of these bleaching LBKPs may be used alone or as a mixed pulp in which two or more kinds of bleaching LBKP are mixed, or one or two or more kinds of bleaching LBKP and one or more kinds of other pulps other than the bleaching LBKP. As the mixed pulp, it can be suitably used. The content concentration of the pulp in the above-mentioned base paper, that is, the pulp paper material solid content for making the base paper is preferably 60% by mass or more, and more preferably 80% by mass or more. In the present invention, it is preferable to improve the whiteness on the dye-receiving layer side of the core material itself made of paper as described above. The thickness of the core material may be arbitrary, and is usually about 10 to 300 μm.

  There are two types of polyolefin resin layers constituting the base sheet, as viewed from the core material, the polyolefin resin layer 1 on the dye-receiving layer side and the polyolefin resin layer 2 on the back side. Examples include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, polyisobutene, polyisobutylene, polybutadiene, polyisoprene, and ethylene copolymers such as ethylene-vinyl acetate copolymer. Medium density polyethylene and low density polyethylene are preferably used. In order to improve whiteness, it is preferable to add a filler such as titanium oxide to the polyolefin resin layer 1 on the dye receiving layer side.

  For the polyolefin resin layer 1 and the polyolefin resin layer 2, the above-mentioned resins can be used. However, in practice, it is preferable to adjust the curl balance and the like of the base sheet by using the same material. The thickness of the polyolefin resin layers 1 and 2 is about 5 to 40 μm. The polyolefin resin layers 1 and 2 can be formed by adjusting the above-mentioned resin coating solution and coating and drying, or can be formed on a core made of paper by a melt extrusion method. In particular, it is efficient and preferable to form the polyolefin resin layer by a melt extrusion method and to form the polyolefin resin layer 1 and the polyolefin resin layer 2 by coextrusion. Further, the formation of the polyolefin resin layer by the extrusion method has an advantage that the thickness can be accurately controlled.

  The substrate sheet of the present invention preferably has a whiteness of 95% or more on the dye receiving layer side. The whiteness specified in the present invention is measured based on JIS Z8722 “Measurement Method of Object Color” 4-3 Condition c, d-O, JIS P8123 “Hunter Whiteness Test Method for Paper and Pulp”. When the whiteness is less than 95%, the whiteness of the base sheet itself is insufficient, and as a result, the whiteness of the image receiving surface of the obtained thermal transfer image receiving sheet becomes insufficient. In order to increase the whiteness of the dye-receiving layer side in the base material sheet to 95% or more, the whiteness of the core material surface can be increased, or the whiteness of the polyolefin resin layer 1 on the dye-receiving layer side can be improved. preferable.

  In the final form in which the whiteness on the dye-receiving layer side of the substrate sheet is 95% or more, and the adhesive layer, porous film, primer layer, and dye-receiving layer described below are laminated on the substrate. By setting the whiteness of the image receiving surface to 95% or more, the whiteness of the image receiving surface is high and the sharpness of the image can be increased.

(Porous film)
The porous film 3 used in the thermal transfer image-receiving sheet of the present invention is not particularly limited as long as it is a porous film having a high surface glossiness, but because of its flexibility, it has excellent adhesion to the thermal head, and productivity. A porous film having a fine void inside is preferred, using polyolefin, particularly polypropylene, as the base resin.

  As a method for producing fine voids in the film, a compound is prepared by kneading organic fine particles or inorganic fine particles (one or more types) incompatible with the resin serving as the base of the film. Microscopically, this compound forms a fine sea-island structure with the base resin and fine particles incompatible with the base resin, and the compound is formed into a film and stretched to form the sea-island interface. The above-mentioned fine voids are generated by peeling off or large deformation of the region forming the island.

  As a method for forming the fine voids, for example, a method in which polypropylene is mainly used and polyester or acrylic resin having a melting point higher than that of polypropylene is added thereto. In this case, polyester or acrylic resin serves as a nucleating agent that forms fine voids. It is preferable that content of this polyester and an acrylic resin is 2-10 mass parts with respect to 100 mass parts of polypropylene in any case. When the content is less than 2 parts by mass, the generation of fine voids is insufficient, so that sufficient printing sensitivity cannot be obtained. Moreover, when content exceeds 10 mass parts, since the heat resistance of a porous film, etc. fall, it is unpreferable.

  Moreover, when producing the porous film which uses polypropylene as the base resin, it is preferable to add polyisoprene in order to generate finer and more dense voids. Thereby, higher printing sensitivity can be obtained. For example, a porous film having high printing sensitivity can be obtained by preparing a compound composed mainly of polypropylene, blended with acrylic resin or polyester, and polyisoprene, forming a compound, and stretching. The thickness of the porous film is preferably 30 μm or more, particularly preferably 30 to 60 μm. If the thickness of the porous film is less than 30 μm, the porous film is crushed when an image is printed, and the image quality is impaired. On the other hand, when the thickness exceeds 60 μm, the image becomes good, but the thermal transfer image-receiving sheet becomes unnecessarily thick, which is not preferable in terms of cost.

(Adhesive layer)
The adhesive layer 5 for laminating the base sheet and the porous film can be appropriately selected according to a laminating method such as dry lamination, wet lamination, and a method of bonding by electron beam irradiation after pasting. Yes, it is not limited. As an adhesive used in the adhesive layer, for example, vinyl acetate resin, acrylic resin, vinyl acetate-acrylic copolymer resin, vinyl acetate-vinyl chloride copolymer resin, ethylene-vinyl acetate copolymer resin, polyamide resin, The thing which uses polyvinyl acetal resin, polyester resin, polyurethane resin, etc. as a component is mentioned.

(Dye-receiving layer)
The dye receiving layer 4 in the thermal transfer image receiving sheet of the present invention is for receiving the sublimation dye transferred from the thermal transfer sheet and maintaining the formed image. As the resin for forming the receiving layer, polycarbonate resin, polyester resin, polyamide resin, acrylic resin, cellulose resin, polysulfone resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-acetic acid Examples thereof include vinyl copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polyurethane resins, polystyrene resins, polypropylene resins, polyethylene resins, ethylene-vinyl acetate copolymer resins, and epoxy resins.

  The thermal transfer image-receiving sheet of the present invention can contain a release agent in the receiving layer in order to improve the releasability from the thermal transfer sheet. Various release agents such as solid waxes such as polyethylene wax, amide wax, Teflon (registered trademark), fluorine-based or phosphate-based surfactant, silicone oil, reactive silicone oil, curable silicone oil, etc. Silicone oil, various silicone resins and the like can be mentioned, and silicone oil is preferable. An oily oil can be used as the silicone oil, but a curable oil is preferred. Examples of the curable silicone oil include a reaction curable type, a photo curable type, and a catalyst curable type, and a reaction curable type and a catalyst curable type silicone oil are particularly preferable.

  As the reactive silicone oil, those obtained by reaction-curing amino-modified silicone oil and epoxy-modified silicone oil are preferable. As amino-modified silicone oil, KF-393, KF-857, KF-858, X-22-3680 are used. X-22-3801C (above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like, and epoxy-modified silicone oils such as KF-100T, KF-101, KF-60-164, KF-103 (above, Shin-Etsu Chemical) Etc.). Examples of the catalyst curable silicone oil include KS-705, FKS-770, and X-22-1212 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  The addition amount of these curable silicone oils is preferably 0.5 to 30% by mass of the resin constituting the receiving layer. Further, the release agent layer can be provided by applying the above release agent dissolved or dispersed in a suitable solvent on a part of the surface of the receiving layer, followed by drying. As the release agent constituting the release agent layer, the reaction cured product of the amino-modified silicone oil and the epoxy-modified silicone oil described above is particularly preferable, and the thickness of the release agent layer is 0.01 to 5.0 μm, particularly 0.05-2.0 micrometers is preferable. When forming the receptor layer by adding silicone oil, the release agent layer can be formed even if the silicone oil bleed out on the surface after application is cured. In the formation of the receiving layer, pigments such as titanium oxide, zinc oxide, kaolin, clay, calcium carbonate, fine powder silica and the like are used for the purpose of improving the whiteness of the receiving layer and further enhancing the clarity of the transferred image. Fillers can be added. Further, a plasticizer such as a phthalic acid ester compound, a sebacic acid ester compound, or a phosphoric acid ester compound may be added.

The thermal transfer image-receiving sheet of the present invention has a thermoplastic resin as described above and other necessary additives such as a mold release agent, a plasticizer, a filler, a crosslinking agent, and a curing agent on at least one surface of the base sheet. , A catalyst, a heat release agent, an ultraviolet absorber, an antioxidant, a light stabilizer, and the like are dissolved in a suitable organic solvent, or a dispersion dispersed in an organic solvent or water is used, for example, a gravure printing method It is obtained by applying and drying by a forming means such as a screen printing method or a reverse roll coating method using a gravure plate to form a dye receiving layer. Application of a primer layer and the like, which will be described later, is also performed by the same method as the above-described dye receiving layer forming means. The coating amount of the thus formed are dye-receiving layer, usually, 0.5 to 50 g / m ² approximately in the dry state, preferably 2 to 10 g / m ^2. Such a dye-receiving layer is preferably a continuous coating, but may be formed as a discontinuous coating.

(Primer layer)
Any conventionally known primer layer 6 can be provided between the dye-receiving layer and the porous film for the purpose of providing adhesion between the dye-receiving layer and the porous film, cushioning properties, anti-curling properties, and the like. The binder resin used for the primer layer is polyurethane resin, polyester resin, polycarbonate resin, polyamide resin, acrylic resin, polystyrene resin, polysulfone resin, polyvinyl chloride resin, polyvinyl acetate resin, polyvinyl chloride- Examples include vinyl acetate copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polyvinyl alcohol resins, epoxy resins, cellulose resins, ethylene-vinyl acetate copolymer resins, polyethylene resins, polypropylene resins, and the like. Of these, those having an active hydroxyl group can further be used as a cured product thereof.

The primer layer is composed mainly of the above binder resin, but if necessary, the following fluorescent brightener, ultraviolet absorber, antioxidant, and antistatic agent may be added. In order to enhance whiteness, stilbene compounds, benzimidazole compounds, benzoxazole compounds, etc. are added as fluorescent brightening agents, and titanium oxide, zinc oxide, magnesium carbonate, carbonic acid are added to impart whiteness and concealment. Add calcium, etc., add hindered amine compounds, hindered phenol compounds, benzotriazole compounds, benzophenone compounds, etc. as UV absorbers or antioxidants to increase the light resistance of the prints, or charge A cationic acrylic resin, polyaniline resin, or the like can be added in order to impart preventive properties. The coating amount of the primer layer is preferably about 0.5 to 30 g / m ^{2 in} a dry state.

(Back layer)
Further, a back layer 10 may be provided on the back surface of the thermal transfer image receiving sheet for the purpose of improving the mechanical transportability of the sheet, preventing curling, preventing charging, and the like. In order to improve transportability, it is preferable to add an appropriate amount of an organic or inorganic filler to the binder resin, or to use a resin with high lubricity such as a polyolefin resin or a cellulose resin. In addition, in order to obtain an antistatic function, a layer made of a conductive resin such as an acrylic resin or a conductive filler, a fatty acid ester, a sulfate ester, a phosphate ester, an amide, a quaternary ammonium salt, a betaine, an amino acid A layer to which various antistatic agents such as ethylene oxide adducts are added may be formed as an antistatic layer on the base sheet or between the back layer and the base sheet. The amount of the antistatic agent used varies depending on the layer to which the antistatic agent is added and the type of the antistatic agent, but in any case, the surface electrical resistance value of the thermal transfer image-receiving sheet is preferably 10 ¹³ Ω / cm ² or less. . If it is greater than 10 ¹³ Ω / cm ² , the thermal transfer image-receiving sheets stick to each other due to electrostatic contact, which causes paper feeding troubles. The amount used is preferably 0.01 to 3.0 g / m ² . When the amount of the antistatic agent used is 0.01 g / m ² or less, the antistatic effect is insufficient. On the other hand, when it is 3.0 g / m ² or more, the amount is too uneconomical, and problems such as stickiness occur. There is a case.

Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on mass.
Example 1
A high-density polyethylene resin (J-Rex KH578A, manufactured by Nippon Polyolefin Co., Ltd.) is extruded on both sides of a white base paper that is 150 g / m ² thick uncoated paper, which is the paper core material 7, and the dye receiving layer side. The polyolefin resin layer 1 and the polyolefin resin layer 1 on the white base paper of the paper core material 7 are melt-coextruded so that the polyolefin resin layer 1 is 25 μm after drying and the polyolefin resin layer 2 on the back side is 25 μm after drying. The resin layer 2 was laminated | stacked and the base material sheet 2 was produced.

Using a porous polypropylene film (Toyopearl SS, manufactured by Toyobo Co., Ltd.) having a thickness of 35 μm as the porous film 3, using the base material sheet 2 prepared above and an adhesive having the following composition, gravure The adhesive layer 5 was formed so as to be coated with a coater and dried to have a coating amount of 5 g / m ² , and bonded and laminated by a dry laminating method.
(Coating solution composition for adhesive layer)
Hydroxyl-containing oligomer 16 parts (Takelac A-31, manufactured by Mitsui Chemicals Polyurethanes)
20 parts of urethane oligomer having an isocyanate group (Takenate A-231, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.)
64 parts of ethyl acetate

On the porous film 3 of the laminate in which the porous film 3 and the substrate sheet 2 are bonded to the adhesive layer 5, the primer layer coating liquid having the following composition is dried and the coating amount is 2 g / m ² . After coating with a gravure coater and drying at 110 ° C. for 1 minute, a coating solution for a dye-receiving layer having the following composition is coated thereon with a gravure coater so as to be 4 g / m ² after drying. Then, it was dried at 110 ° C. for 1 minute to produce the thermal transfer image receiving sheet of Example 1.

(Primer layer coating solution 1 composition)
Polyester resin (WR-905, manufactured by Nippon Synthetic Chemical Co., Ltd.) 13.1 parts Titanium oxide (TCA-888, manufactured by Tochem Products) 26.2 parts Optical brightener 0.39 parts (benzimidazole derivative, product) Name: TINOPAL IJT, manufactured by Ciba Specialty Chemicals)
60 parts of water / isopropyl alcohol [IPA] (mass ratio 2/1)

(Coating solution composition for dye-receiving layer)
Vinyl chloride-vinyl acetate copolymer (Solvine C, manufactured by Nissin Chemical Industry Co., Ltd.) 60 parts Epoxy-modified silicone (X-22-3000T, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methylstil-modified silicone (24 -510, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.6 parts methyl ethyl ketone / toluene (mass ratio 1/1) 5 parts

(Comparative Example 1)
Coated paper thickness 154g / m ² (i COAT, Daio Paper Corp.) uncoated surface density polyethylene resin (J. Rex KH578A, Japan Polyolefins Co., Ltd.) and polypropylene (SunAllomer PHA03A (SunAllomer ( Co., Ltd.) was extruded and melt-coextruded so that the polyethylene resin layer was 14 μm and the polypropylene resin layer was 19 μm, and a laminate (coated paper / PE / PP2) was produced.

Adhesive layer coating used in Example 1 using the laminate (coated paper / PE / PP2) produced above and a porous polypropylene film (Toyopearl SS, manufactured by Toyobo Co., Ltd.) having a thickness of 35 μm. Using a liquid, a gravure coater, an adhesive layer is formed so that the coating amount after drying is 5 g / m ² , and the above laminate (coated paper / PE / PP2) coated paper by the dry laminating method The two were bonded together and laminated so that the porous polypropylene film and the porous polypropylene film were opposed to each other, and a laminate of (PP1 / adhesive layer / coated paper / PE / PP2) was produced. Gravure so that the coating amount after drying with the primer layer coating solution used in Example 1 is 2 g / m ² on PP1 of the above laminate (PP1 / adhesive layer / coated paper / PE / PP2). After coating with a coater and drying at 110 ° C. for 1 minute, the coating solution for the dye-receiving layer used in Example 1 is dried thereon and coated with a gravure coater so that the coating amount becomes 4 g / m ^2. Then, it was dried at 110 ° C. for 1 minute to produce a thermal transfer image receiving sheet of Comparative Example 1.

  Regarding the thermal transfer image-receiving sheets of the above-described examples and comparative examples, the whiteness of the image-receiving surface in the image-receiving paper form produced under the above conditions, and the base material sheet in which polyolefin resin layers are provided on both sides of the core material made of paper in the examples The whiteness on the dye-receiving layer side, and in the comparative example, the whiteness of the surface of the coated paper in the laminate (coated paper / PE / PP2) was measured under the following conditions.

  Whiteness: JIS Z8722 “Measurement method of object color” 4-3 Conditions c, d-O, JIS P8123 “Whiteness test method for paper and pulp hunter whiteness”, the measuring instrument is “OPTRON BRIGHTNESS (( Toyo Seiki Seisakusho Co., Ltd.) was used.

The measurement results of the whiteness are shown in Table 1.

It is a schematic sectional drawing which shows one embodiment of the thermal transfer image receiving sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal transfer image receiving sheet 2 Base material sheet 3 Porous film 4 Dye receiving layer 5 Adhesive layer 6 Primer layer 7 Paper core material 8 Polyolefin resin layer 1
9 Polyolefin resin layer 2
10 Back layer

Claims (1)

A base sheet comprising a polyolefin resin layer on both sides of a core made of paper is used as a base sheet, and the base sheet and the porous film are bonded together with an adhesive layer, and a primer layer is interposed on the porous film. A thermal transfer image-receiving sheet provided with a dye-receiving layer, wherein the whiteness of the substrate sheet on the dye-receiving layer side is 95% or more.

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