JPH06155942A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer image receiving sheet having high sensitivity, excellent in dot reproducibility and forming an image free from blur by providing a non-porous thermoplastic resin layer between the porous intermediate layer and heat-resistant surface layer successively laminated on a support. CONSTITUTION:A thermal transfer image receiving sheet is obtained by successively laminating a porous intermediate layer containing hollow particles and a heat-resistant surface layer composed of a radiation-curable resin on a support and arranging an image receiving layer receiving the dye transferred from a thermal transfer medium at the time of heating on this laminate. In the above mentioned constitution, a non-porous thermoplastic resin layer is provided between the porous intermediate layer and the heat-resistant surface layer. The center line average roughness (Ra) of the thermoplastic resin layer is set to 1.0mum or less. The thickness of the heat-resistant surface layer is set to 2-15mum and the average particle size of the hollow particles is set to 0.7-7mum. The radiation-curable resin is a compd. having an acryloyl group in its molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image-receiving sheet for thermal transfer, which has high sensitivity, excellent dot reproducibility, and has no image bleeding.

[0002]

2. Description of the Related Art In recent years, a thermal transfer recording system has been widely used as a means of color hard copy because it is lightweight and compact, has no noise, and has excellent operability and maintainability. ing. This thermal transfer recording system is roughly classified into two types, which are a heat melting type and a heat transfer type or a sublimation type. In particular, the latter is excellent in reproducibility of multicolor gradation images and is printed using a sublimation type thermal transfer type printer. The principle of such a sublimation type thermal transfer type printer is that a sheet in which an image is converted into an electric signal and the electric signal is further converted into a heat signal by a thermal head and a heat transfer dye is applied (ink donor sheet). Information is recorded by transferring the dye from the ink donor sheet to the image-receiving layer of the thermal transfer image-receiving sheet by heating and by sublimation or diffusion in the medium. Particularly in recent years, it has been required to improve the transfer density from the viewpoint of increasing the printing speed, and in order to achieve such high sensitivity, it is necessary to include hollow particles having excellent heat insulating properties and cushioning properties in the intermediate layer between the substrate and the image receiving layer. The fact that it is effective is described in, for example, Japanese Patent Laid-Open No. 64-27996.

[0003]

However, such a hollow particle is inferior in heat resistance because the wall material is formed of a thermoplastic resin such as vinylidene chloride or styrene-acryl, so that it is not heated by heat during printing. For the purpose of improving heat insulation and cushioning, especially for improving sensitivity, as well as having drawbacks such as shrinkage, lack of dot reproducibility of the image, and heat curling on the heating print surface. When the content of the hollow particles is increased, the smoothness of the surface is further increased when treated or stored under warm conditions before use due to the high thermal expansion coefficient of the gas contained in the hollow particles. And the reproducibility of dots during printing is reduced. The treatment under such a heating condition is usually carried out in order to improve the blocking resistance by promoting the crosslinking reaction of the image receiving layer after coating the image receiving layer in the manufacturing process of the thermal transfer image receiving sheet. Storage under warm conditions is also commonly performed. In the intermediate layer containing such hollow particles or between the intermediate layer and the image receiving layer, for example, JP-A Nos. 62-278088 and 64-279.
A surface layer having no heat-shrinkability as in Japanese Patent Publication No. 96,
Alternatively, on the assumption that the image-receiving layer is coated with an organic solvent, an attempt has been made to provide an organic solvent-resistant polymer compound layer, and the material forming these layers is, for example, a styrene-butadiene-based or acid-based material. Since it is a thermoplastic polymer compound such as vinyl acetate emulsion, polyvinyl alcohol, and casein, after forming an image-receiving layer on the layer to form an image-receiving sheet for thermal transfer, heating conditions are applied to improve blocking resistance. When processed or stored in, the image receiving layer surface became rough and became a cause of dot omission. Further, such a thermoplastic resin has a drawback that part of the image-receiving layer penetrates into the heat-resistant surface layer to cause image bleeding, especially when the print after printing is stored under high temperature conditions.

[0004]

On the other hand, a porous intermediate layer containing hollow particles as a main component is provided on a substrate made of cellulose fiber paper or a synthetic resin film, and a non-porous heat layer is formed on the intermediate layer. An image-receiving sheet for thermal transfer which has excellent dot reproducibility and does not cause image bleeding by providing a plastic resin layer, forming a heat-resistant surface layer made of a radiation-curable resin on it, and further providing an image-receiving layer thereon. I was able to get or,
In order to achieve the above conditions, the non-porous thermoplastic resin layer having a center line average roughness (Ra) of 1.0 μ or less and an average particle size of hollow particles of 0.7 μ to 7 μ is used. By adjusting the thickness of the heat-resistant surface layer to 2 to 15 μm, it was possible to obtain a thermal transfer image-receiving sheet with higher sensitivity, excellent dot reproducibility, and image bleeding.

The present invention will be described in detail below. Examples of the hollow particles include heat-expandable hollow particles and capsule-shaped hollow polymers. The thermally expandable hollow particles are hollow particles having a thermoplastic material such as vinylidene chloride-acrylonitrile copolymer as a wall material, and a material containing a thermally expandable gas such as propane, n-butane and isobutane inside the particles. Is. Further, the capsule-shaped hollow polymer is a polymer having a resin such as styrene-acryl as a wall material and having water inside, and when the water is dried, the water flies to form hollow particles. The hollow particles as described above generally have an average particle size of about 0.1 to 50 μ, but in the present invention, hollow particles having a particle size of about 0.7 to 7 μ are preferably used. . 0.7
Even if hollow particles with a small particle size of less than μ are used, 0.7μ
Not only is there a large difference in sensitivity from the use of hollow particles of the above particle size, but there is also an unfavorable effect such as an increase in the viscosity of the coating liquid, and the use of hollow particles of 7 μm or larger makes the surface smoothness of the intermediate layer In order to obtain a high-quality thermal transfer image-receiving sheet, in order to obtain a highly smooth heat-resistant surface layer, it is necessary to increase the coating thickness of the non-porous thermoplastic resin layer or heat-resistant surface layer. This is because the heat insulating effect due to the hollow particles and the sensitivity increasing effect due to the cushion effect are offset. The content ratio of the hollow particles in the porous intermediate layer is 80 to 40 by weight.
Weight percent is preferred. If the content exceeds 80%, the surface strength of the coating layer is lowered, and when the non-porous thermoplastic resin layer is provided on the intermediate layer, the coating layer penetrates into the intermediate layer, which is not preferable. If it is less than 40%, the effect of improving the sensitivity due to the heat insulating property of the hollow particles is low, and the object of the present invention is not achieved.

The non-porous thermoplastic resin layer provided on the porous intermediate layer does not contain hollow particles, and as a raw material of the thermoplastic resin, a natural or synthetic thermoplastic resin layer which is usually used is used. Molecular compounds can be used. For example, specific examples include water-soluble polymers such as polyvinyl alcohol and starch, polyester resins, polyacrylic acid ester resins, polycarbonate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyamide resins (nylon), A copolymer containing a synthetic resin such as a urea resin, a polycaprolactone resin, a polystyrene resin, a polyvinyl chloride, or a polyacrylonitrile resin as a main component of at least one of the constitutional units of the above resin, for example, vinyl chloride-vinyl acetate. It can also be used as a copolymer, a styrene-butadiene copolymer or the like, and the above resins can be used alone or in combination of two or more. Further, the above resin may be dissolved in water or an organic solvent and applied on the porous intermediate layer, or emulsified in an aqueous solution and applied as an emulsion. The coating amount of the thermoplastic resin can be usually set in the range of 3 to 20 μm so that the center line average roughness (Ra) is preferably 1.0 μm or less. It is also possible to smooth the surface by calendering after applying the intermediate layer or after applying the non-porous thermoplastic resin layer.

On the other hand, when a heat resistant surface layer made of a radiation curable resin is provided on top of the above porous intermediate layer and a non-porous thermoplastic resin layer, dot reproducibility is excellent because of excellent heat resistance. It was possible to obtain a support having good image quality and no image blur. The thickness of the heat resistant surface layer is preferably set in the range of 2 μm to 15 μm. When the thickness is 2 μm or less, the film formation is not sufficient in general, and when the thickness is 15 μm or more, the heat insulating property and cushioning property of the intermediate layer containing the hollow particles under the radiation curable resin are effectively utilized. Not obtained, the transfer density decreases. As a method of applying a heat-resistant surface layer made of a radiation curable resin on the intermediate layer containing hollow particles, for example, blade coating, air doctor coating, squeeze coating, air knife coating, reverse roll coating,
Methods such as gravure roll and transfer roll coating, bar coating and curtain coating are used. or,
If necessary, a heat-resistant surface layer made of a radiation-curable resin is provided between the non-porous thermoplastic resin layer and the high-smoothness film. The support may be manufactured by peeling the permeable film. In addition, a metal roll with high smoothness is used instead of the high smoothness film, and a layer made of a radiation curable resin is provided between the non-porous thermoplastic resin layer and the metal roll to prevent radiation while it has plasticity. It is also possible to form a highly smooth surface by irradiating.

The ionizing radiation for curing the radiation-curable resin composition is generally ultraviolet rays, α rays, β rays, γ.
Rays, X-rays, electron rays, etc. are mentioned, but α-rays, β-rays, γ-rays, or X-rays are easily handled and are widely used industrially because they pose a problem of danger to the human body. Effective ultraviolet rays and electron beams are used.

When an electron beam is used, the amount of the electron beam to be irradiated is preferably adjusted within the range of 0.1 to 10 Mrad, and particularly preferably within the range of 2 to 6 Mrad. When it is 0.1 Mrad or less, a sufficient irradiation effect cannot be obtained, and when it is 10 Mrad or more, the film substrate is deteriorated, which is not preferable. As an electron beam irradiation method, a scanning method, a curtain beam method, or the like is adopted, and an accelerating voltage for irradiating the electron beam is preferably about 100 to 300 KV.

When ultraviolet rays are used, it is necessary to add a sensitizer to the radiation curable resin composition.
Specific examples thereof include acetophenones such as di- or trichloroacetophenone, benzophenone,
There are Michler's ketone, benzyl, benzoin, benzoin alkyl ether, benzyl dimethyl ketal, tetramethyl thiuram monosulfide, thioxanthones, azo compounds, etc., and the type, stability, and radiation of the polymerization reaction of radiation curable resin and radiation curable silicone resin. It is selected from the viewpoint of compatibility with the irradiation device. The amount of the photosensitizer used is usually in the range of 1 to 5% with respect to the radiation curable resin or the radiation curable silicone resin. In addition, a storage stabilizer such as hydroquinone may be used in combination with the photosensitizer. Examples of the light source include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp,
A tungsten lamp or the like is preferably used.

It is preferable that the heat-resistant surface layer provided on the non-porous thermoplastic resin layer has a high smoothness in order to obtain good image quality, but the surface roughness is the center line average roughness (R).
The material is not particularly limited as long as it is 1.0 μm or less, preferably 0.5 μm or less. The thickness ratio of the heat resistant surface layer to the non-porous thermoplastic resin layer is 2 to 0.2.
Is preferred. If the thickness ratio of the heat-resistant surface layer is increased to 2 or more, the effect of improving the sensitivity due to the cushioning property of the thermoplastic resin decreases, and the sensitivity tends to decrease. On the contrary, when the ratio is 0.2 or less and the thickness of the heat resistant surface layer is reduced, the weakness of heat resistance, which is a defect of the thermoplastic resin, appears and the dot reproducibility is deteriorated. The total thickness of the non-porous thermoplastic resin layer and the heat resistant surface layer is preferably about 5μ to 30μ. If the thickness is less than 5μ, the film formation is not sufficient and 3
When it is 0 μ or more, the effect of improving the sensitivity due to the heat insulating property of the hollow particles is offset.

The radiation-curable resin used in the heat-resistant surface layer of the present invention is a compound having a reactive group such as an acryloyl group, a methacryloyl group, or an epoxy group at the molecular end or in the molecular side chain, and is an unsaturated polyester. , Modified unsaturated polyester, acrylic polymer, acrylic monomer, methacrylic polymer, methacrylic monomer and monomer or oligomer having vinyl type unsaturated bond, epoxy compound and the like can be used alone or together with other solvents. Hereinafter, representative ones will be exemplified.

(A) Polyester acrylate, polyester methacrylate; for example, Aronix M-53
00, Aronix M-5400, Aronix M-5
500, Aronix M-5600, Aronix M-
5700, Aronix M-6100, Aronix M
-6200, Aronix M-6300, Aronix M-6500, Aronix M-7100, Aronix M-8030, Aronix M-8060, Aronix M-8100 (above, Toa Gosei Chemical Industry Co., Ltd. trade name), Viscoat 700, Viscoat 3700 (above,
Product name of Osaka Organic Chemical Industry Co., Ltd., Kayarad HX-2
20, Kayarad HX-620 (Nippon Kayaku Co., Ltd.)
Product name)

(B) Epoxy acrylate, epoxy methacrylate; for example, NK ester, EA-800,
NK Ester, EPM-800 (above, trade name of Shin-Nakamura Chemical Co., Ltd.), Viscoat 600, Viscoat 540
(Above, product name of Osaka Organic Chemical Industry Co., Ltd.), Photomer 3016, Photomer 3082 (above, product name of San Nopco Co., Ltd.)

(C) Urethane acrylate, urethane methacrylate; for example, Aronix M-1100, Aronix M-1200, Aronix M-1210,
Aronix M-1250, Aronix M-126
0, Aronix M-1300, Aronix M-13
10 (above, trade name of Toagosei Chemical Industry Co., Ltd.), viscoat 812, viscoat 823, viscoat 823 (above, trade name of Osaka Organic Chemical Industry Co., Ltd.), NK ester,
U-108-A, NK ester, U-4HA (above, Shin Nakamura Chemical Co., Ltd. trade name)

(D) Monofunctional acrylate, monofunctional methacrylate; for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, tetrahydrofuran. Furyl acrylate, phenoxyethyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, benzyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, butoxyethyl acrylate and the like. Ethylene oxide-modified phenoxyphosphoric acid acrylate Ethylene oxide-modified butoxylated phosphoric acid acrylate, and other trade names of Toagosei Kagaku Kogyo Co., Ltd. are Aronix M-101, Aronix M-102, Aronix M-111, Aronix M-113. , Aronix M-114, Aronix M-117, Aronix M-152, Aronix M-154 and the like.

(E) Polyfunctional acrylate, polyfunctional methacrylate; for example, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene. Glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, pentaerythritol diacrylate, dipentaerythritol hexaacrylate, isocyanuric acid diacrylate, pentaerythritol triacrylate, isocyanuric acid triacrylate, trimethylolpropane triacrylate, trimethylolpropane triacrylate Methacrylate, ethylene oxide modified polyethylene Examples thereof include ethylene erythritol tetraacrylate, propylene oxide-modified pentaerythritol tetraacrylate, propylene oxide-modified dipentaerythritol polyacrylate, and ethylene oxide-modified dipentaerythritol polyacrylate. The product names of Toagosei Kagaku Kogyo Co., Ltd. are Aronix M-210, Aronix M-215, Aronix M-220, Aronix M-230, Aronix M-233, Aronix M-240, Aronix M-245, Aronix M. -305, Aronix M-309, Aronix M-310, Aronix M
-315, Aronix M-320, Aronix M-
325, Aronix M-330, Aronix M-4
00, TO-458, TO-747, TO-755, T
HIC. TA2 etc. are mentioned.

(F) Epoxy compound: glycidyl methacrylate, 1,3-bis (N, N-diepoxypropylaminomethyl) cyclohexane, 1,3-bis (N, N-diepoxypropylaminomethyl) benzene and the like can be mentioned. .
The product name of Mitsubishi Gas Chemical Co., Ltd. is GE-510,
Examples include TETRAD-X and TETRAD-C.

However, when the radiation-curable resin is not sufficiently cured by the radiation, the image-receiving layer after transfer of the dye is gradually provided on the radiation-curable resin layer, probably because it exhibits thermoplasticity. There is a case where it penetrates into the inside and causes image bleeding. To prevent this bleeding, it is necessary to strengthen the radiation energy. However, depending on the support, the strength may be deteriorated, and it has become clear as a result of the study by the present inventors that a resin having essentially high radiation curing reactivity is preferable for image bleeding.

From this point of view, it was found that a compound containing an acryloyl group in the molecule and having an acryloyl equivalent of 190 or less can be particularly preferably used for the purpose of the present invention. The acryloyl equivalent is a numerical value obtained by dividing the molecular weight by the number of acryloyl groups in the molecule, and the smaller the numerical value, the higher the density of the photocrosslinking functional group.

Representative examples of resins that can be used in the present invention are illustrated in the Aronix series of Toagosei Kagaku Kogyo Co., Ltd., along with the trade name and acryloyl equivalent, but the present invention is not limited thereto. . The value in () indicates acryloyl equivalent. M-7100 (188.7), M
-8030 (119.1), M-8060 (136.
1), M-150 (111.0), M-220 (14
1.0), M-230 (153.8), M-240 (1
42.0), M-305 (99.3), M-309 (9
8.7), M-310 (156.7), M-315 (1
41.0), M-400 (96.3), M-5600.
(165.6), M-325 (179.9), M-81.
00 (155.0), M-9050 (181.4)

The present inventors have also found that a trifunctional or higher functional aliphatic radiation curable resin can be preferably used.
When an aliphatic radiation curable resin having a functionality of 2 or less is used, it tends to cause image blurring due to its low crosslink density,
Further, in the case of a radiation curable resin containing an aromatic group in the molecule, its large aromatic ring tends to accelerate the penetration of the image-receiving layer into the heat-resistant surface layer. As described above, it has been clarified that a support having excellent dot reproducibility and free from image bleeding can be obtained by using a trifunctional or higher functional aliphatic radiation curable resin.

The trifunctional or higher functional aliphatic radiation curable resin used in the heat resistant surface layer of the present invention has a reactive group such as an acryloyl group, a methacryloyl group or an epoxy group at the molecular end or at the molecular side chain. Unsaturated polyester, modified unsaturated polyester, acrylic polymer, acrylic monomer, methacrylic polymer, methacrylic monomer and monomer or oligomer having vinyl type unsaturated bond, epoxy compound, etc. alone or together with other solvent Can be used.

Representative examples will be illustrated below. In Toagosei Co., Ltd., Aronix M-309, Aronix M-310, Aronix M-315, Aronix M-320, Aronix M-325, Aronix M-400, etc. are illustrated, and in Nippon Kayaku Co., Ltd.,
KAYARAD TMPTA, KAYARAD TPA
-320, KAYARAD TPA-320, KAYA
RAD PET-30, KAYARAD D-310,
KAYARAD D-330, KAYARAD DPH
A, KAYARAD DPCA-20, KAYARAD
DPCA-30, KAYARAD DPCA-60,
KAYARAD DPCA-120, etc., and in Daiichi Kogyo Seiyaku Co., Ltd., New Frontier TMPT, New Frontier TMP-3, New Frontier TMP-.
3P, New Frontier PET-3, etc. at Osaka Organic Chemical Industry Co., Ltd., Viscoat # 295, Viscoat #
300, Viscoat # 360, Viscoat GPT, Viscoat 3PA, Viscoat # 400, etc., Arakawa Chemical Co., Ltd. beam set 720, and San Nopco Ltd., Photomer 4072-SN, Photomer 4094, Photomer 4149-SN, etc. , Shin Nakamura Chemical Co., Ltd., NK ester TMPT, NK ester
TMM-360, NK ester A-TMPT, NK ester A-TMPT-U, NK ester A-TMPT
-3ED, NK ester A-TMPT-3PO, NK
Ester A-TMPT-3EO, NK Ester A-
TMPT-3EO-U, NK ester A-TMM-
3, NK ester A-TMM-3L, NK ester
A-TMMT, NK ester PA-1000, NK ester PA-2000, NK ester ATM-4E,
NK Ester ATM-4P, NK Ester AD-T
In MP, etc., Kyoeisha Oil and Fat Chemical Co., Ltd., TMP-A
Etc., Daicel UCB Co., Ltd.
MPTA, Shrimpryl TMPEOTA, Shrimpryl
OTA480, Shrimpryl PETIA, Shrimpryl
EB160, Shrimpryl EB254, Shrimpryl E
B264, Evicryl EB265, Evicryl EB
294, Evicryl EB295, Evicryl EB1
259, Evicryl EB4866, Evicryl EB1
290K is shown as a specific example.

The above-mentioned conditions for the radiation-curable resin having an acryloyl equivalent of 190 or less or the tri-functional or more aliphatic radiation-curable resin may satisfy either one or both of the conditions, and the heat resistance of the present invention. In the surface layer, the above radiation-curable compounds can be used alone or in combination,
In addition, if necessary, if the main component is the above compound,
Other radiation-curable resin compositions can be used in combination as long as the content is at least wt%. Further, if necessary, color pigments, white pigments and the like can be used, and specific examples of white pigments include barium sulfate, titanium dioxide (rutile type and anatase type), zinc sulfide, calcium carbonate, magnesium oxide, various types. Silicate, aluminum oxide, titanium phosphate, satin white, talc,
Examples include clay and the like. Especially from the viewpoint of high whiteness,
Barium sulfate, titanium dioxide, calcium carbonate and the like are preferably used. The white pigment content is 15% by weight.
When it is less than 50%, the whiteness is unsatisfactory, and when it is more than 50% by weight, the liquidity of the coating liquid is poor and a uniform and highly smooth surface cannot be obtained, which causes deterioration of image quality. Since the layer becomes brittle, stress cracks and cracks are likely to occur.
In addition, an antistatic agent, a fluorescent whitening agent and the like may be added to the heat resistant surface layer, if necessary. Various kneaders can be used for kneading and dispersing the coating composition. For example, as the kneader, a two roll mill, a three roll mill, a ball mill, a sand grinder, a high speed stone mill, a kneader, a homogenizer, etc. are useful. The coating may be carried out in a solvent-free system, or may be dissolved or dispersed in water or an organic solvent to remove the solvent after coating and then be radiation-cured.

The substrate used in the present invention includes cellulose fiber paper or synthetic resin film, and the above-mentioned cellulose fiber paper laminated with synthetic resin film can also be used. Examples of the cellulose fiber paper include high-quality paper, coated paper, art paper, synthetic resin or emulsion-impregnated paper, and synthetic resin films commonly used for polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polycarbonate, etc. Whether the film is porous or non-porous, it can be appropriately used according to the purpose. Further, the above cellulose fiber paper obtained by extrusion coating a polyolefin or the like can also be used. The thickness of the substrate is preferably 50μ to 500μ.

On the heat-resistant surface layer of the present invention, an image receiving layer having a dyeing property to a dye which is melted or sublimated by heat and migrates is provided to form a thermal transfer image receiving sheet, and the image receiving layer is formed. As the dye-dyeable binder resin to be used, any one can be suitably used as long as it has a strong interaction with the dye and the dye can be stably diffused in the resin. As having, polyester resin,
Polyacrylic ester resin, polycarbonate resin,
Polyvinyl acetate resin, styrene acrylate resin, etc .;
Polyurethane resin having urethane bond; polyamide resin (nylon) having amide bond; urea resin having urea bond; and other highly polar bond Can be a polycaprolactone resin, a polystyrene resin, a polyvinyl chloride, a polyacrylonitrile resin, or the like, or a copolymer containing at least one of the structural units of the above resin as a main component, for example, vinyl chloride-vinyl acetate. It can also be used as a copolymer, a styrene-butadiene copolymer or the like, and the above resins can be used alone or in combination of two or more. The above resin may be dissolved in water or an organic solvent and applied on the heat resistant surface layer, or may be emulsified in an aqueous solution and applied as an emulsion, but if necessary, it may be applied on the heat resistant surface layer. It is also possible to improve the adhesion with the image receiving layer by subjecting it to an easy-adhesion treatment. As a method of making the heat-resistant surface layer easily adhesive, a method of modifying the heat-resistant surface layer surface by corona treatment, plasma treatment, or the like,
Alternatively, a resin having good adhesiveness may be applied to both the heat resistant surface layer and the image receiving layer. As such a resin, any resin having good adhesiveness to both layers can be preferably used. For example, an acrylic resin, a vinyl chloride resin, a vinyl acetate resin, a urethane resin, a styrene butadiene resin or a resin thereof can be used. Examples thereof include polymers and the like. The coating amount of the above image-receiving layer can be appropriately set in the range of 0.5 to 10.0 g / m ² in terms of dry solid content.

In the present invention, the release agent added to the image receiving layer is used for the purpose of preventing blocking. Specific examples include waxes such as higher fatty acids or esters thereof, amides or metal salts thereof, shellac wax, montan wax, carnauba wax, polyethylene wax and Teflon powder; fluorine-based and phosphoric acid ester-based surfactants; silicones. Examples include oil. Further, as the silicone oil, modified silicone oil such as amino-modified silicone, epoxy-modified silicone, alkyd-modified silicone, polyester-modified silicone and the like can be used. Further, as the silicon compound, a hardening type silicon compound can be used if necessary.
Examples of the curable silicon compound include a reaction curable type, an ionizing radiation curable type, and a catalyst curable type.

Further, if necessary, dyes, pigments, wetting agents,
The image receiving layer may contain additives such as a defoaming agent, a dispersant, an antistatic agent, a fluorescent brightening agent, an ultraviolet absorber and a light stabilizer. Particularly with respect to the pigment, inorganic particles represented by silica, alumina, titanium oxide, calcium carbonate, kaolin, clay, zinc oxide, barium sulfate and the like can be added.

Further, a backside layer containing inorganic fine powder is provided on the backside opposite to the image receiving layer with respect to the substrate in order to impart slipperiness with a roll at the time of transfer and writability to the backside layer after transfer. Alternatively, an antistatic agent may be contained in the back surface layer for the purpose of antistatic. When an adhesive resin is mixed in the back surface layer, it is also possible to mix the adhesive resin and an antistatic agent to cause bleeding on the surface of the resin layer, and consequently to provide it on the resin layer. As the antistatic agent, a surfactant,
For example, a cationic surfactant (quaternary animonium salt,
Examples thereof include polyamine derivatives), anionic surfactants (alkyl phosphates, etc.), zwitterionic surfactants and nonionic surfactants.

[0031]

According to the present invention, a porous intermediate layer containing hollow particles and a non-porous thermoplastic resin layer are provided, and a heat resistant surface layer made of a radiation curable resin is provided on the thermoplastic resin layer. By providing an image-receiving layer on top of it, it was possible to obtain an image-receiving sheet for thermal transfer which has high sensitivity and excellent dot reproducibility and has no image bleeding.

[0032]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples. In addition, "part" in an Example is a weight part. The ink donor sheet for evaluation was prepared as follows. Kayaset Blue 906 (Nippon Kayaku, sublimation dye) 10 parts Ethyl Semellose 10 parts Syloid 244 (Fuji Devison silica gel) 10 parts Isopropyl alcohol 30 parts After sublimating dye solution for 2 days with a ball mill, heat treatment is applied. Approximately 2. with a wire bar on the coated polyester film.
5 g / m ^{2 was} applied to obtain a donor sheet.

Example 1 On a coated paper, a porous intermediate layer having the following composition was applied at a dry solid content of 30 g / m ² , and then polyvinyl alcohol was applied as a non-porous thermoplastic resin to a thickness of 3 μm. , The surface Ra was adjusted to 0.2 μm, and then a heat resistant surface layer having the following composition was kneaded and dispersed with a three-roll mill and applied onto the thermoplastic resin layer to have a particle size of 3 μ, and electron beam irradiation (acceleration) was performed. The heat resistant surface layer was cured at a voltage of 200 KV and an irradiation dose of 5.0 Mrad. (Composition of porous intermediate layer) Hollow particles Grosdale 1161-EX (Mitsui Toatsu: particle size 0.9μ) 70 parts Styrene-butadiene latex 28 parts Thickener 2 parts (heat resistant surface layer composition) Aronix M-309 75 Part Titanium dioxide 25 parts On the above heat-resistant surface layer, a polyester resin emulsion (Vylonal MD-120 was prepared with an air knife coater.
0: Toyobo) and silica (Aerosil 200: Nippon Aerosil) as inorganic fine particles having a dry solid content of 3.5.
An image-receiving sheet for thermal transfer was obtained by coating and drying so as to have g / m ² and 0.5 g / m ² .

Example 2 A porous intermediate layer having the following composition was coated on a polyolefin laminated paper at a dry solid content of 25 g / m ² , and then polyvinyl alcohol and SB were used as a non-porous thermoplastic resin layer.
R latex was applied at a ratio of 1: 1 in terms of solid content to a thickness of 5μ to adjust the surface Ra to 0.4 μm, and then KAYA
RAD D-330 is diluted with an organic solvent and applied on the thermoplastic resin layer, and after removing the solvent, electron beam irradiation (accelerating voltage: 1
A heat resistant surface layer was provided so as to have a thickness of 10 μm at 50 KV and an irradiation dose of 5.0 Mrad, and an image receiving sheet for thermal transfer was obtained.
On the above heat-resistant surface layer, polyester resin (Vylon 200: Toyobo) dissolved in an organic solvent was added, and alkyd-modified silicon was added to dry solids of 2.5 g / m ² and 0.5, respectively.
An image-receiving sheet for heat-sensitive transfer was obtained by coating and drying so as to have g / m ² . (Combined with porous intermediate layer) Hollow particle Microsphere MB943 (Hornen: particle size 3μ) 50 parts Urethane emulsion 48 parts Thickener 2 parts

Example 3 On a cast-coated paper, a porous intermediate layer having the following composition was applied at a dry solid content of 20 g / m ² and then polyvinyl alcohol was applied as a thermoplastic resin in a thickness of 7 μ to form a layer surface. After adjusting Ra to 0.9 μm, a heat-resistant surface layer having the following composition was applied using a gravure offset coater so as to have a thickness of 12 μ, and a high smoothness polyester film was attached to the applied surface, and electron beam irradiation (acceleration voltage: 200K
After curing with V and an irradiation dose of 5.0 Mrad, the polyester film was peeled off, and then the polyester resin emulsion (Vylonal MD-1 was used with an air knife coater.
200: Toyobo Co., Ltd.) and colloidal silica (Snowtex O: Nissan Kagaku Co., Ltd.) as inorganic fine particles to a dry solid content of 4.0 g / m ² and 0.5 g / m ² , respectively, and dried for thermal transfer image reception. Got the sheet. (Composition of porous intermediate layer) Hollow particle Microsphere MB927 (Hornen: particle size 7μ) 40 parts Urethane emulsion 58 parts Thickener 2 parts (Heat resistant surface layer composition) New Frontier PET-30 (Daiichi Kogyo Seiyaku) 85 Part Titanium dioxide 15 parts

Comparative Example 1 On a coated paper, a porous intermediate layer having the following composition was applied at a dry solid content of 30 g / m ^2, and then a heat resistant surface layer having the following composition was kneaded and dispersed by a three roll mill to obtain 25 μm. Coating on the intermediate layer, and electron beam irradiation (accelerating voltage: 200K
The heat resistant surface layer was cured with V and an irradiation dose of 5.0 Mrad. (Composition of porous intermediate layer) Hollow particle microsphere porous material (Hornen: particle size 10 µ) 40 parts Styrene-butadiene latex 58 parts Thickener 2 parts (Heat resistant surface layer composition) Aronix M-309 75 parts Titanium dioxide 25 parts On the above heat-resistant surface layer, a polyester resin emulsion (Vylonal MD-120 with an air knife coater was used.
0: Toyobo) and silica (Aerosil 200: Nippon Aerosil) as inorganic fine particles having a dry solid content of 3.5.
An image-receiving sheet for thermal transfer was obtained by coating and drying so as to have g / m ² and 0.5 g / m ² .

Comparative Example 2 In Example 2, HX-2 was used as the radiation curable resin.
An image receiving sheet for thermal transfer was obtained in the same manner as in Example 2 except that 20 (aliphatic and bifunctional) was used.

Comparative Example 3 An image receiving sheet for thermal transfer was obtained in the same manner as in Comparative Example 1 except that Aronix M-6250 (aromatic and bifunctional) was used as the radiation curable resin.

Comparative Example 4 Instead of using the radiation-curable resin in Example 2, a urethane primer was applied to a thickness of 10 μm, an image receiving layer was provided in the same manner as in Example 2, and an image receiving sheet for thermal transfer was provided. Got

The thermal transfer image-receiving sheet thus obtained is 40
After left at 3 ° C. for 3 days, the ink donor sheets were placed face to face with each other and printed with S3600-30 manufactured by Mitsubishi Electric. Regarding the blurring in the image, the degree of dot diffusion when the printed sample was left at 60 ° C. for 200 hours was observed and evaluated according to the following criteria. The dot reproducibility was evaluated on a scale of 5 with 5 being good, 1 having a large dot defect, and 3 being the middle. The results are shown in Table-1.
As for the transfer density, the reflection density was measured with a Macbeth densitometer. 1: It can be seen with the naked eye that the printed matter is carrot. 2: It can be seen with the naked eye that the printed matter is a little carrot. 3: Observing with a magnifying glass, you can see bleeding. 4: Observing with a magnifying glass, you can see that it is a little carrot. 5: No bleeding is observed even when observed with a magnifying glass.

[0041]

[Table 1]

[0042]

The effect of the present invention is that a porous intermediate layer containing hollow particles, a non-porous thermoplastic resin layer and a heat resistant surface layer comprising a radiation curable resin are laminated on a substrate, and By providing an image receiving layer on the top, a thermal transfer image receiving sheet having high sensitivity, excellent dot reproducibility, and no image blur was obtained.

Claims (6)

[Claims] 1. A porous intermediate layer containing hollow particles and a heat-resistant surface layer made of a radiation-curable resin are sequentially laminated on a substrate, and further thereon, by heat melting or sublimation from a thermal transfer medium during heating. An image-receiving sheet for thermal transfer provided with an image-receiving layer that receives a dye that migrates, characterized in that a non-porous thermoplastic resin layer is provided between the porous intermediate layer and the heat-resistant surface layer. Image receiving sheet. 2. The thermoplastic resin layer has a center line average roughness (R
The image receiving sheet for thermal transfer according to claim 1, wherein a) is 1.0 μm or less. 3. The thermal transfer image-receiving sheet according to claim 1, wherein the heat-resistant surface layer has a thickness of 2 to 15 μm. 4. The thermal transfer image-receiving sheet according to claim 1, 2 or 3, wherein the hollow particles have an average particle size of 0.7 μm to 7 μm. 5. The radiation curable resin is a compound having an acryloyl group in its molecule, and the acryloyl equivalent of the compound is 190 or less.
An image-receiving sheet for thermal transfer according to item 2, 3 or 4. 6. The image-receiving sheet for thermal transfer according to claim 1, wherein the radiation-curable resin is a trifunctional or higher functional aliphatic radiation-curable resin.