JP2009078428A - Thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet in which pre-printing curl can be stably prevented and with which an image having excellent surface smoothness, high clarity, no density irregularity or the like can be obtained, even when a film obtained by slitting a raw film which is widely formed and manufactured into several lines, is used for a support. <P>SOLUTION: The thermal transfer image receiving sheet includes at least a sheet base material for which a plastic film is stuck to and laminated on both sides of a paper core material and a dye acceptance layer which is provided to one side of the sheet base material. The plastic film on the dye acceptance layer side of the sheet base material is a plastic film having micro voids, while the plastic film on the other side of the sheet base material is a plastic film having no micro voids. A difference between the orientation angle (θ2) of the plastic film having no micro voids and the orientation angle (θ1) of the plastic film having micro voids is set to be ≤60° in ¾θ2-θ1¾. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet, and more particularly to a thermal transfer image receiving sheet that can stably prevent curling before printing, has excellent surface smoothness, high sharpness, and has no density unevenness. .

Among various thermal transfer recording systems, sublimation dye recording using a sublimation dye as a color material, and sublimation transfer recording that obtains an image by transferring it to an image receiving sheet using a thermal head that generates heat according to the recording signal or laser light. The method is known. This recording method uses dye as a color material and density gradation is possible, so the image is very clear and halftone color reproducibility and gradation reproducibility are excellent. Images with comparable image quality can be formed. With the above-mentioned excellent performance and the development of various hardware and software related to the multimedia, the sublimation transfer recording system is a computer graphics, a still image by sanitary communication, and a digital image represented by CD-ROM and others. As a full-color hard copy system for analog images such as video, the market is rapidly expanding.

  The specific uses of the thermal transfer image-receiving sheet of this sublimation transfer recording system are diverse. Typical examples include printing proofs, image output, CAD / CAM and other design and design output, photographic image output from digital cameras, various types of medical analysis equipment such as CT scan, and output of measurement equipment. And as an alternative to instant photos, output of face photos to ID cards, ID cards, credit cards, and other cards, as well as composite photos and amusement photos at amusement facilities such as amusement parks, museums, aquariums, etc. Can be mentioned.

  As a performance required for the thermal transfer image-receiving sheet used in various applications as described above, it is needless to say that high printing sensitivity is obtained, but it is sufficient to obtain an image with higher sharpness and no density unevenness. There is an increasing market demand for uniform appearance, ie, a uniform and smooth surface. The sublimation transfer method is designed to increase the recording speed (line speed). However, to increase the sensitivity of the thermal transfer image-receiving sheet, the heat generated by the thermal head must be used efficiently for image formation. Has become an issue. In contrast, in order to reduce the heat loss, the support of the image receiving sheet is made of a plastic film mainly composed of a thermoplastic resin that is smooth, cushioning and adhesive, and has high heat insulating properties. .

  However, when a plastic film alone is used as a support for the image receiving sheet, curling occurs during storage of the sheet-like thermal transfer image receiving sheet at room temperature or at an atmosphere of 40, 50 ° C. There is a problem that it becomes low and causes a conveyance trouble in the thermal transfer printer. On the other hand, as disclosed in Patent Document 1, a sheet-like support in which a plurality of films are laminated and bonded has been proposed. However, the conditions in which a plurality of films are simply laminated and bonded are insufficient to prevent curling before printing and after printing.

  In contrast, in Patent Documents 2 and 3, the layer structure of the sheet-like support is non-axisymmetric about the core material, that is, films having different heat shrinkage rates are bonded to the front and back of the core material. In addition, it has been proposed to prevent the curling by defining the correlation between the heat shrinkage rate and the thickness of the film to be bonded to the front and back of the core material. However, even if such a method is used, the raw film produced by being formed in a wide width is slit into several rows and bonded to the core material to prepare a support, and then the dye receiving layer and the like are processed. When the sheet is cut into a sheet (sheet cut) and commercialized, the curl of the thermal transfer image-receiving sheet before printing is largely caused by the difference in the row of the original film, and the curl is small. There is a problem that there is a variation in curling property and a product with stable quality cannot be manufactured.

JP-A-62-198497 Japanese Patent Publication No. 5-33918 JP-A-3-55295

  Therefore, the present invention has been made in view of such a situation, and even when a film obtained by slitting a raw film produced in a wide width into several rows is used as a support, curling before printing is performed. It is an object of the present invention to provide a thermal transfer image-receiving sheet that can be stably prevented, has excellent surface smoothness, has high sharpness, and has no density unevenness.

  The thermal transfer image-receiving sheet of the present invention comprises, as claim 1, at least a sheet base material obtained by laminating and laminating a plastic film on both sides of a paper core, and a dye receiving layer provided on one surface of the sheet base material. In the thermal transfer image-receiving sheet, the plastic film on the dye-receiving layer side of the sheet substrate is a plastic film having microvoids, and the plastic film on the other side of the sheet substrate is a plastic film having no microvoids, and the microvoids The difference between the orientation angle (θ2) of a plastic film not having a thickness and the orientation angle (θ1) of a plastic film having a microvoid is within θ ° of | θ2−θ1 |. As described above, curling can be stably prevented in the thermal transfer image-receiving sheet before printing by suppressing the difference in orientation angle (| θ2-θ1 |) of the plastic film to be bonded to both surfaces of the paper core material within 60 °. be able to.

  According to a second aspect of the present invention, the plastic film bonded to both sides of the paper core material is a polyethylene terephthalate film on both sides. Thereby, it has heat resistance and the curling prevention property before printing improves more.

  The thermal transfer image-receiving sheet of the present invention is a support having a sheet base material obtained by laminating and laminating a plastic film on both sides of a paper core material, and supports a film obtained by slitting a raw film produced in a wide width into several rows. Even when used on the body, by using a combination of plastic films on both sides so that the difference in orientation angle (| θ2−θ1 |) of the plastic film bonded to both sides of the paper core is within 60 ° Thus, it was possible to stably prevent curling before printing, and to obtain an image having excellent surface smoothness, high sharpness, and no density unevenness.

  FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermal transfer image-receiving sheet 1 of the present invention. An adhesive layer 3, a plastic film 4 having microvoids, a primer layer 5, and a dye on one surface of a paper core 2. The receiving layer 6 is laminated in order, and the adhesive layer 7, the plastic film 8 having no microvoids, the primer layer 9, and the back layer 10 are sequentially laminated on the other surface of the paper core 2. A laminated body of plastic film 4 having microvoids / adhesive layer 3 / paper core material 2 / adhesive layer 7 / plastic film 8 having no microvoids is a sheet substrate 11 as a support. If there is no problem in adhesiveness even if the primer layers 5 and 9 are removed, they can be omitted as appropriate, and a detection mark, a logo, or the like can be printed on the back layer side.

Hereinafter, each layer constituting the thermal transfer image receiving sheet of the present invention will be described in detail.
(Support)
The support 11 used in the present invention has a laminated structure of a plastic film 4 having microvoids / adhesive layer 3 / paper core material 2 / adhesive layer 7 / plastic film 8 having no microvoids.
(Paper core material)
As the paper core material 2, a paper base material mainly composed of cellulose fibers such as coated paper, art paper, glassine paper, high-quality paper, cast-coated paper, or the like is used. The thickness of the paper core material may be arbitrary, and is usually about 10 to 300 μm. Particularly preferably, the thickness is 110 to 140 μm.

(Plastic film)
Examples of the plastic film to be bonded to both sides of the paper core material include polypropylene film, polyethylene film, polyethylene terephthalate film, polyethylene naphthalate film, polycarbonate film, polyetheretherketone film, polyamide film, and polyethersulfone film. . Especially, a polyethylene terephthalate film has heat resistance, is easily available, and is preferably used.

  The above plastic film has microvoids, no microvoids, and any material is as described above in terms of material. However, as the plastic film 4 having microvoids, the following two methods are used. Microvoids can be generated in the plastic film. One is a method in which inorganic fine particles are kneaded in a polymer, and when the compound is stretched, microvoids are generated using the inorganic fine particles as nuclei. The other is to create a compound blended with an incompatible polymer (one or more types) for the main resin. When this compound is viewed microscopically, the polymers form a fine sea-island structure. When this compound is stretched, microvoids are generated by separation of the sea-island interface or large deformation of the polymer forming the island.

  The plastic film 8 having no microvoids is manufactured by stretching and molding the resin as described above, and the film is not provided with microvoids (fine voids). Use a plastic film on the dye-receiving layer side of the support that has microvoids. The thermal transfer image-receiving sheet can have cushioning and heat insulation properties, high print sensitivity and print density, and sharpness of the image. It is because it can be made high. In addition, the plastic film having no microvoids is used as the plastic film on the side opposite to the dye-receiving layer side of the support. The plastic film having microvoids is expensive and has a slightly inferior strength. This is because a plastic film having no microvoids can maintain a sufficient strength even if it is suppressed without increasing its thickness, so that the total thickness of the entire thermal transfer image-receiving sheet can be prevented from increasing. The thickness of the plastic film is usually about 10 to 100 μm, preferably 20 to 50 μm, regardless of whether the microvoids are included or not.

  In the present invention, the difference between the orientation angle (θ2) of the plastic film 8 not having microvoids and the orientation angle (θ1) of the plastic film 4 having microvoids is | θ2−θ1 | within 60 °. It is what. However, the orientation angle of the plastic film of the present invention was measured using a microwave molecular orientation meter (model name: MOA-3001A) manufactured by Oji Scientific Instruments Co., Ltd., and the major axis 20 as the optical principal axis was relative to the width direction of the film. Indicates a corner. Specifically, in FIG. 2, the orientation of molecules at the orientation angle is indicated by the major axis 20 in the optical orientation direction, and the direction orthogonal to the major axis is indicated by the minor axis 30. When the orientation angle is +, as shown in FIG. 2 (1), the major axis 20 is tilted to the lower right with respect to the film width direction, and the angle indicated by the arrow is the orientation angle (+). On the other hand, when the orientation angle is-, as shown in FIG. 2 (2), the major axis 20 is tilted in the upper right direction with respect to the film width direction, and the angle indicated by the arrow is the orientation angle (-). . Therefore, the orientation angle is 0 to ± 90 ° and does not exceed 90 °.

  The condition of the present invention is that the difference between the orientation angle (θ2) of the plastic film 8 not having microvoids and the orientation angle (θ1) of the plastic film 4 having microvoids is within 60 ° at | θ2−θ1 |. However, the difference in orientation angle (| θ2−θ1 |) is preferably closer to 0 because the support has higher anti-curl property. Since the film is stretched in the direction of the orientation angle of the film regardless of the presence or absence of microvoids, that is, in the direction of the major axis 20 shown in FIG. 2, the film tends to expand and contract in that direction, so that it has microvoids. This is because the curling of the support can be prevented by performing the bonding in such a direction that the orientation angle of the plastic film 4 and the orientation angle of the plastic film 8 having no microvoids strike each other. When the difference in orientation angle (| θ2−θ1 |) exceeds 60 °, the thermal transfer image-receiving sheet has a large curl before printing, has a low commercial value, and easily causes a conveyance trouble in the thermal transfer printer. Regardless of the presence or absence of microvoids, a plastic film produced by extrusion stretching tends to have a large absolute value even if there is a difference between the orientation angles on both sides of the wide width. However, even if the plastic film itself has a large orientation angle, the difference between the orientation angles (| θ2) of the plastic film 4 having microvoids bonded to both surfaces of the paper core material and the plastic film 8 not having microvoids. By using in combination such that −θ1 |) is within 60 °, it is laminated as a support, and curling before printing can be stably prevented.

(Adhesive layer)
The adhesive layers 3 and 7 for bonding and adhering the paper core material and the plastic film described above are made of an adhesive. The adhesive is not particularly limited as long as it has an adhesive function. For example, polyolefin resin such as urethane resin, α-olefin-maleic anhydride resin, polyester resin, acrylic resin, epoxy resin, etc. Resins, urea resins, melamine resins, phenol resins, vinyl acetate resins, cyanoacrylate resins, and the like can be used. Among them, a reactive type of acrylic resin or a modified one can be preferably used. In addition, it is preferable to cure the adhesive using a curing agent because the adhesive force is improved and the heat resistance is increased. As the curing agent, an isocyanate compound is generally used, but aliphatic amines, cycloaliphatic amines, aromatic amines, acid anhydrides and the like can be used. The thickness of the adhesive layer is in coating amount is usually, ² to 10 g / m ² about 2 g / m in the dry state. For the formation of the adhesive layer, commonly used coating means can be used, for example, by means of gravure printing, screen printing, reverse roll coating using a gravure plate, etc. To do.

  The sheet substrate 11 as a support for the thermal transfer image-receiving sheet of the present invention has a structure in which a plastic film is laminated on both sides of a paper core material, and the lamination method is dry lamination, wet lamination, non-solvent lamination. Well-known methods such as EC lamination and heat sealing can be used. The adhesive layer may be applied to the paper side or may be applied to the plastic film side, but it is preferably applied to the paper core side in order to effectively erase the paper texture. .

(Primer layer)
The thermal transfer image receiving sheet of the present invention may be one in which a primer layer 5 is formed between a sheet base material 11 as a support and the dye receiving layer 6. Such a primer layer is for improving the adhesion between the sheet substrate and the dye receiving layer, and can be formed of polyurethane resin, acrylic resin, polyethylene resin, polypropylene resin, epoxy resin, etc. The coating amount is preferably about 0.1 to 20 g / m ² when dried.

(Dye-receiving layer)
The dye receiving layer 6 in the thermal transfer image receiving sheet in 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. Examples of the release agent include solid waxes such as polyethylene wax, amide wax, and Teflon (registered trademark) powder, fluorine-based or phosphate-based surfactant, silicone oil, various silicone resins, and the like, but 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, a curing agent on one surface of the sheet base material. A dispersion obtained by dissolving a catalyst, a heat release agent, an ultraviolet absorber, an antioxidant, a light stabilizer, etc. in an appropriate organic solvent or dispersed in an organic solvent or water, for example, gravure printing, 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. 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.

(Back layer)
The thermal transfer image-receiving sheet of the present invention has a back layer 10 on the surface opposite to the dye-receiving layer of the sheet substrate for the purpose of improving the mechanical transportability of the sheet, imparting writing properties and antistatic properties, and the like. May be. Examples of the resin constituting the back layer include polyvinyl alcohol (PVA) resin, polyurethane resin, polyester resin, polybutadiene resin, poly (meth) acrylate resin, epoxy resin, polyamide resin, rosin-modified phenol resin, terpene phenol. Resins, ethylene-vinyl acetate copolymer resins, polyolefin resins, cellulose resins, polyvinyl butyral resins, polyvinyl acetal resins and the like can be mentioned.

  When forming the back layer, for example, (1) In addition to the above-exemplified resins, etc., an appropriate amount of organic filler or inorganic filler is added, or (2) a resin having high lubricity, such as a polyolefin resin or a cellulose resin. When used, it is possible to obtain a thermal transfer image-receiving sheet with improved sheet mechanical transportability. When a known filler, pigment, or the like is blended when forming the back layer, the writing property can be imparted to the obtained thermal transfer image-receiving sheet.

Moreover, in order to obtain the antistatic function, the back layer was added with various antistatic agents such as conductive resin such as acrylic resin and / or fatty acid ester, sulfuric acid ester, phosphoric acid ester, ethylene oxide adduct, etc. It may be a thing. The amount of the antistatic agent used varies depending on the type and amount of the antistatic agent used, but the surface electrical resistance value of the thermal transfer image-receiving sheet is 10 ¹³ Ω / cm ² or less in order to prevent paper feeding troubles. It is preferable to mix | blend so that it may become. The back layer can be formed by coating and drying by a known method, and it is preferable to coat the back layer so that the amount is 0.5 to 5 g / m ² after drying.

  By providing the back layer on the sheet base material via the primer layer 9, the adhesiveness between the two can be improved. The primer layer 9 at that time can be similarly applied to the material, thickness, etc. described in the primer layer 5 provided between the sheet base material and the dye receiving layer.

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
Using a polyethylene terephthalate film 4 having a microvoid with a thickness of 35 μm under the condition that the orientation angle (θ1) is −16 °, a primer layer and a dye receiving layer coating solution having the following composition are obtained by a gravure reverse coating method. The primer layer 5 and the dye receiving layer 6 are formed by coating and drying sequentially, and the polyethylene terephthalate film 4 having microvoids opposite to the surface on which the primer layer 5 and the dye receiving layer 6 are provided has the following composition: The adhesive layer 3 is formed by applying and drying three reverse roll coats using the adhesive layer coating solution, and the paper core 2 has a basis weight of 129 g / m ² and a thickness of 130 μm. A thing was used and bonded together. The respective coating amounts were all in a dry state, the primer layer 5 was 1.5 g / m ² , the dye receiving layer 5 was 5.0 g / m ² , and the adhesive layer 3 was 5 g / m ² .

(Coating liquid composition for primer layer 5)
Polyester resin (Vaironal MD-1480, manufactured by Toyobo Co., Ltd.) 10 parts Silicate (Laponite JS, manufactured by Wilber Ellis Co., Ltd.) 10 parts Wetting property improver (Surfinol 104, Nisshin Chemical Industry Co., Ltd.) Made) 0.5 part water 79.5 parts

(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

(Coating liquid composition for adhesive layer)
Urethane resin (Takelac A969V, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.) 30 parts Isocyanate compound (Takenate A5, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.) 10 parts Ethyl acetate 120 parts

Further, a polyethylene terephthalate film 8 having a thickness of 25 μm and not having microvoids is used in a gravure reverse coating method using a film having an orientation angle (θ2) of −14 °, which is different from that used above. The primer layer coating liquid having the composition and the coating liquid for the back surface layer having the following composition are sequentially applied and dried to form the primer layer 9 and the back surface layer 10, and the surface on which the primer layer 9 and the back surface layer 10 are provided; The polyethylene terephthalate film 8 having no microvoids on the opposite surface is coated with a coating solution for an adhesive layer having the same composition as that used above and dried by a reverse roll coating method to form an adhesive layer 7. Then, the sheet base material prepared above was bonded to the paper core side to prepare the thermal transfer image receiving sheet of Example 1. (See FIG. 1) Each coating amount was in a dry state, the primer layer 9 was 1.5 g / m ² , the back surface layer was 2.0 g / m ² , and the adhesive layer 7 was 5 g / m ² . . In the sheet base material in Example 1, the difference in the orientation angle (| θ2−θ1 |) of the plastic film bonded to both surfaces of the paper core was 2 °.

(Coating liquid composition for primer layer 9)
Polyurethane (N5199, manufactured by Nippon Polyurethane Industry Co., Ltd.) 50 parts Titanium oxide (TCA-888, manufactured by Tochem Products Co., Ltd.) 50 parts Methyl ethyl ketone / toluene (mass ratio 1/1) 400 parts

(Coating solution composition for back layer)
Polyvinyl butyral (# 5000A, manufactured by Denki Kagaku Kogyo Co., Ltd.) 30 parts Microsilica (Silicia 730, manufactured by Fuji Silysia Co., Ltd.) 60 parts Microsilica (Silicia 310, manufactured by Fuji Silysia Co., Ltd.) 30 parts Chelating agent 5 (Orga Chicks TC-750, manufactured by Matsumoto Fine Chemical Co., Ltd.)
Nylon filler (MW-330, manufactured by Shinto Paint Co., Ltd.) 5 parts Isopropyl alcohol / toluene (mass ratio 1/1) 500 parts

  The thermal transfer image-receiving sheet of Example 1 obtained above was sized in a width direction of 100 mm × length of 177 mm, in a 50 ° C. oven at 24 hours, 48 hours, and 168 hours with the dye-receiving layer surface facing up. After storage, the sheet was taken out of the oven, and the thermal transfer image receiving sheet was immediately examined on the horizontal plate for the curl heights at the four corners. (The curl height was examined in two ways: when the dye-receiving layer surface was facing up and when the back surface layer surface was facing up, and a value with a large curl height was employed.) In the thermal transfer image-receiving sheet of Example 1, In all the three storage conditions, the maximum curl height was 4.5 mm, and the thermal transfer image-receiving sheet before printing had little curl and excellent surface smoothness. Further, when the thermal transfer image-receiving sheet of Example 1 was printed by a thermal transfer printer, there was no conveyance trouble, and a good image with high sharpness and no density unevenness was obtained.

(Example 2)
In the thermal transfer image-receiving sheet prepared in Example 1 above, the polyethylene terephthalate film 4 having a microvoid with a thickness of 35 μm was changed to a film with an orientation angle (θ1) of −33 °, and a microvoid with a thickness of 25 μm was provided. The polyethylene terephthalate film 8 that was not used was changed to a film having an orientation angle (θ2) of −38 ° to prepare a sheet base material. Other conditions were the same as in Example 1, and a thermal transfer image-receiving sheet of Example 2 was produced. In the sheet base material in Example 2, the difference in orientation angle (| θ2−θ1 |) of the plastic film bonded to both surfaces of the paper core was 5 °.

  The thermal transfer image-receiving sheet of Example 2 was stored under the above-mentioned three storage conditions as in Example 1, and the curl height was 6.5 mm at the maximum when all the front and back sides were seen. Thermal transfer before printing As the image receiving sheet, the curl was small and the surface smoothness was excellent. In addition, when the thermal transfer image-receiving sheet of Example 2 was printed by a thermal transfer printer, there was no conveyance trouble, and a good image with high sharpness and no density unevenness was obtained.

(Example 3)
In the thermal transfer image-receiving sheet prepared in Example 1 above, the polyethylene terephthalate film 4 having a microvoid with a thickness of 35 μm was changed to a film with an orientation angle (θ1) of −16 °, and a microvoid with a thickness of 25 μm was provided. The polyethylene terephthalate film 8 that was not used was changed to a film having an orientation angle (θ2) of 14 ° to prepare a sheet base material. Other conditions were the same as in Example 1, and a thermal transfer image-receiving sheet of Example 3 was produced. In the sheet base material in Example 3, the difference (| θ2−θ1 |) in the orientation angle of the plastic film bonded to both surfaces of the paper core was 30 °.

  The thermal transfer image-receiving sheet of Example 3 was stored under the above-mentioned three storage conditions as in Example 1, and the curl height was 9.5 mm at the maximum when all the front and back sides were seen. Thermal transfer before printing As the image-receiving sheet, the curl was not large, was in an acceptable range, and had excellent surface smoothness. Further, when the thermal transfer image-receiving sheet of Example 3 was printed by a thermal transfer printer, there was no conveyance trouble, and a good image with high sharpness and no density unevenness was obtained.

(Comparative Example 1)
In the thermal transfer image-receiving sheet prepared in Example 1 above, the polyethylene terephthalate film 4 having a microvoid with a thickness of 35 μm was changed to a film with an orientation angle (θ1) of −33 °, and a microvoid with a thickness of 25 μm was provided. The polyethylene terephthalate film 8 that was not used was changed to one having an orientation angle (θ2) of 38 ° to produce a sheet substrate. Other conditions were the same as in Example 1, and a thermal transfer image-receiving sheet of Comparative Example 1 was produced. In the sheet base material in Comparative Example 1, the difference in orientation angle (| θ2−θ1 |) of the plastic film bonded to both surfaces of the paper core was 71 °.

  The thermal transfer image-receiving sheet of Comparative Example 1 was stored under the above-mentioned three storage conditions as in Example 1, and the curl height was 14.5 mm at the maximum when all the front and back sides were seen. Thermal transfer before printing Although the image receiving sheet was excellent in surface smoothness, the curl was large. Further, when the thermal transfer image-receiving sheet of Comparative Example 1 was printed by a thermal transfer printer, a conveyance trouble such as a jam occurred at the time of paper feeding or in the vicinity of the recording unit, and a defect occurred in the obtained image.

It is a schematic sectional drawing which shows one embodiment of the thermal transfer image receiving sheet of this invention. It is a figure which illustrates schematically the case where the orientation angle of a plastic film is +, and-.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal transfer image receiving sheet 2 Paper core material 3 Adhesion layer 4 Plastic film which has a micro void 5 Primer layer 6 Dye receiving layer 7 Adhesion layer 8 Plastic film which does not have a micro void 9 Primer layer 10 Back layer 11 Sheet base material (support)
20 Long axis 30 Short axis

Claims (2)

  In a thermal transfer image-receiving sheet having at least a sheet base material obtained by laminating and laminating a plastic film on both sides of a paper core material, and a dye receiving layer provided on one side of the sheet base material, the dye base of the sheet base material The plastic film on the layer side is a plastic film having microvoids, the plastic film on the other side of the sheet substrate is a plastic film having no microvoids, and the orientation angle (θ2) of the plastic film having no microvoids is The thermal transfer image-receiving sheet, wherein the difference in orientation angle (θ1) of the plastic film having microvoids is within 60 ° at | θ2−θ1 |. The thermal transfer image receiving sheet according to claim 1, wherein the plastic film to be bonded to both surfaces of the paper core material is a polyethylene terephthalate film on both surfaces.

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