JP2011079328A - Thermal transfer image receiving sheet and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet maintaining high density printing characteristics while utilizing the advantage of a coating system and stably keeping printing homogeneity regardless of the delicate change of a drying process after coating and the storage at a high temperature after the manufacture and to provide a manufacturing method thereof. <P>SOLUTION: In the thermal transfer image receiving sheet having at least a heat-insulating layer and an image receiving layer on a substrate, at least one of the layers is formed by the coating system, the viscosity of the coating liquid of the layer at 40°C is 200 mPa s and the viscosity at 15°C is 20 times the viscosity at 40°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet and a method for producing the same.

  Conventionally, as a color or monochrome image forming technique, an ink sheet containing a heat diffusible dye having a property of diffusing and transferring by heating is opposed to a receiving layer of an image receiving sheet, and a thermal printing unit such as a thermal head or a laser. A technique (so-called dye thermal transfer system) is known in which a heat diffusible dye is transferred onto an image receiving layer as an image by using a toner. Such a thermal transfer system is well-established as a method that enables image formation using digital data, does not use a processing solution such as a developer, and can form a high image quality comparable to a silver salt photograph.

  In order to obtain good printing characteristics in such a dye thermal transfer recording method, it has been conventionally recognized that it is important to provide a thermal transfer image receiving sheet with a heat insulating function and a cushion function.

  For this proposition, for example, a method is known in which a foamable film having both functions of heat insulation and cushion is bonded on a substrate and an image receiving layer is provided thereon. As a result, the foamable film contracted due to the heat, causing problems such as curling as a final product. In order to eliminate the curling caused by the thermal history of the manufacturing process and the study of newly providing a functional layer having a heat insulating and cushioning function for such defects, a thermal transfer image receiving sheet that does not have a bonding process such as a foam film. Various studies have been made on manufacturing methods such as coating methods.

  For example, in a thermal transfer image receiving sheet in which an intermediate layer and an image receiving layer are sequentially provided on a base material, hollow particles having a particle diameter of 0.1 to 100 μm, or particles obtained by thermally expanding a thermally expandable plastic material in the intermediate layer There is disclosed a thermal transfer image-receiving sheet composed of a microcapsule-shaped hollow polymer particle having a diameter of 0.1 to 20 μm and a layer mainly composed of an organic solvent-resistant polymer (see Patent Document 1). However, in general, when hollow particles are used, a high filling rate of particles must be ensured in order to obtain a sufficient heat insulating effect, and disorder of surface smoothness due to a low binder ratio cannot be avoided. In addition, due to this, the thickness of the organic solvent-resistant layer coated on the hollow particle-containing layer also becomes non-uniform, and the organic solvent used when coating the image receiving layer penetrates from the relatively thin part. The hollow particle wall surface is dissolved to cause uneven printing. Furthermore, there is a dilemma that the printing density decreases when the layer thickness of the organic solvent resistance is increased to avoid this.

  In response to such a problem, for example, in an image receiving sheet in which a porous layer containing hollow particles, an intermediate layer, and an image receiving layer are sequentially formed on a cellulose paper base material, thermal transfer in which the binder resin of the hollow particles is a water-soluble resin An image-receiving sheet, preferably a thermal transfer image-receiving sheet in which the hollow particle ratio in the porous layer is 70 to 90% by mass and the porous layer resin is polyvinyl alcohol having an average polymerization degree of 1000 or more ( For example, see Patent Document 2.) However, the above proposed method cannot suppress the floating of the hollow particles in the porous layer in the drying process in industrialization, and the unevenness level on the surface of the porous layer changes due to subtle variations in drying, resulting in image reception. There was a drawback that unevenness of printing occurred due to the smoothness of the layer. In addition, even when there was no problem with the printing uniformity immediately after the image receiving sheet was produced, there was a strong tendency for printing unevenness to become apparent after storage at high temperatures.

Therefore, while taking advantage of the coating method, thermal transfer image receiving that maintains high density printing characteristics and can maintain uniform printing uniformity regardless of subtle changes in the drying process after coating and high-temperature storage after production. There has been a strong demand for a sheet and a manufacturing method thereof.
Japanese Patent Laid-Open No. 11-321128 JP 2002-192842 A

  The present invention has been made in view of the above problems, and its purpose is to maintain the high-density printing characteristics while taking advantage of the coating method, and to subtle variations in the drying process after coating and high-temperature storage after production. The present invention provides a thermal transfer image-receiving sheet and a method for producing the same that can stably maintain printing uniformity.

  The above object of the present invention is achieved by the following configurations.

(Aspect 1 of the present invention)
In a thermal transfer image-receiving sheet having at least a heat insulating layer and an image-receiving layer on a substrate, at least one of the layers is formed by a coating method, and the viscosity at 40 ° C. of the coating solution of the layer is 200 mPa · s or less, A thermal transfer image-receiving sheet, wherein the viscosity at 15 ° C is 20 times or more of the viscosity at 40 ° C.

(Aspect 2 of the present invention)
At least two layers are formed by a coating method, and the viscosity of 40 ° C. of the coating liquid of all the layers formed by the coating method is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times the viscosity at 40 ° C. It is the above, The thermal transfer image receiving sheet of aspect 1 characterized by the above-mentioned.

(Aspect 3 of the present invention)
The thermal transfer image-receiving sheet according to aspect 2, wherein at least two layers formed by the coating method are coated simultaneously.

(Aspect 4 of the present invention)
In a thermal transfer image-receiving sheet having at least a heat-insulating layer, an intermediate layer and an image-receiving layer on a substrate, at least the heat-insulating layer and the intermediate layer are formed by a coating method, and the viscosity at 40 ° C. of the coating solution of the layer is 200 mPa · s. The thermal transfer image-receiving sheet according to aspect 2 or 3, wherein the thermal transfer image-receiving sheet has a viscosity at 15 ° C of 20 times or more of a viscosity at 40 ° C.

(Aspect 5 of the present invention)
In a method for producing a thermal transfer image-receiving sheet having at least a heat insulating layer and an image-receiving layer on a substrate, at least one of them is formed by a coating method, and the viscosity at 40 ° C. of the coating solution of the layer is 200 mPa · s or less. A method for producing a thermal transfer image-receiving sheet, wherein the viscosity at 15 ° C. is 20 times or more of the viscosity at 40 ° C.

(Aspect 6 of the present invention)
At least two layers are formed by a coating method, and the viscosity of 40 ° C. of the coating liquid of all the layers formed by the coating method is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times the viscosity at 40 ° C. The method for producing a thermal transfer image receiving sheet according to the aspect 5, which is as described above.

(Aspect 7 of the present invention)
The method for producing a thermal transfer image receiving sheet according to the aspect 6, wherein at least two layers formed by the coating method are coated simultaneously.

(Aspect 8 of the present invention)
In a method for producing a thermal transfer image-receiving sheet having at least a heat insulating layer, an intermediate layer and an image receiving layer on a substrate, at least the heat insulating layer and the intermediate layer are formed by a coating method, and the coating solution of the layer has a viscosity of 40 ° C. The method for producing a thermal transfer image-receiving sheet according to the aspect 6 or 7, wherein the viscosity is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times or more the viscosity at 40 ° C.

  According to the present invention, while taking advantage of the coating method, high density printing characteristics can be maintained, and printing uniformity can be stably maintained regardless of subtle variations in the drying process after coating and high-temperature storage after production. Such a thermal transfer image receiving sheet and a method for producing the same can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the inventors of the present invention have the following configuration in a thermal transfer image-receiving sheet having at least a heat insulating layer, an intermediate layer, and an image-receiving layer on a substrate. This makes it possible to maintain high density printing characteristics while taking advantage of the cost / environment of the coating method, and to stabilize printing uniformity regardless of subtle variations in the drying process after coating and high-temperature storage after production. As a result, the present inventors have found that a thermal transfer image-receiving sheet that can be maintained by the present invention can be provided.

  That is, in the first invention, at least the heat insulating layer and the image receiving layer are provided on the substrate, at least one of them is formed by a coating method, and the coating solution of the layer has a viscosity of 40 ° C. The viscosity is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times or more the viscosity at 40 ° C. By adopting the above configuration, it is possible to form and maintain a stable layer that is less affected by subtle fluctuations in manufacturing conditions and storage at high temperatures, and as a thermal transfer image-receiving sheet, excellent print uniformity is maintained while maintaining a high density. Obtainable.

  In the second invention, at least a heat insulating layer and an image receiving layer are provided on the substrate, and at least two of them are formed by a coating method, and the coating solution of the layer has a viscosity at 40 ° C. of 200 mPa · The viscosity at 15 ° C. is 20 times or more of the viscosity at 40 ° C. By adopting the above configuration, it is possible to form and maintain a stable layer that is less affected by subtle fluctuations in manufacturing conditions and storage at high temperatures, and as a thermal transfer image-receiving sheet, excellent print uniformity is maintained while maintaining a high density. Obtainable.

  In the third invention, at least a heat insulating layer and an image receiving layer are provided on the substrate, all of the layers are formed by a coating method, and the viscosity of the coating solution at 40 ° C. is 200 mPa · s or less. The viscosity at 15 ° C. is 20 times or more the viscosity at 40 ° C. By adopting the above configuration, it is possible to form and maintain a stable layer that is less affected by subtle fluctuations in manufacturing conditions and storage at high temperatures, and as a thermal transfer image-receiving sheet, excellent print uniformity is maintained while maintaining a high density. Obtainable.

  In the fourth invention, at least a heat insulating layer, an intermediate layer and an image receiving layer are provided on the substrate, at least the heat insulating layer and the intermediate layer are formed by a coating method, and the coating solution of the layer is 40 ° C. The viscosity is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times or more the viscosity at 40 ° C. By adopting the above configuration, it is possible to form and maintain a stable layer that is less affected by subtle fluctuations in manufacturing conditions and storage at high temperatures, and as a thermal transfer image-receiving sheet, excellent print uniformity is maintained while maintaining a high density. Obtainable.

  Details of the present invention will be described below.

<Thermal transfer image-receiving sheet>
First, the details of the thermal transfer image receiving sheet of the present invention will be described.

  The thermal transfer image receiving sheet of the present invention has at least a heat insulating layer and an image receiving layer on a substrate. Furthermore, the coating liquid used in the present invention preferably contains a viscosity increasing agent in order to increase the viscosity at a low temperature. The viscosity increasing agent is not particularly limited as long as it increases the viscosity under a certain condition, but a hardening agent is particularly preferably used.

  The hardening agent that can be used in the present invention is not particularly limited as long as it causes a hardening reaction with the binder, but boric acid and its salts and epoxy hardening agents are preferred. In addition, known compounds can be used and are generally compounds having a group capable of reacting with a hydrophilic binder or compounds that promote the reaction between different groups of the hydrophilic binder, depending on the type of binder. Are appropriately selected and used. Specific examples of the hardener include, for example, epoxy hardeners (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N- Diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde hardeners (formaldehyde, glioxal, etc.), active halogen hardeners (2,4-dichloro-4-hydroxy-1) , 3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), isocyanate compounds, zirconyl sulfate, aluminum alum, etc. Can be mentioned.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts. Boric acid having a boron atom and a salt thereof as a hardener may be used as a single organic solvent solution, an aqueous solution, or a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax. The aqueous solutions of boric acid and borax can be added only as relatively dilute aqueous solutions, respectively, but by mixing them both can be made into a concentrated aqueous solution and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

  The amount of the hardener used is preferably 1 to 1000 mg, more preferably 100 to 1000 mg, per 1 g of binder.

  The coating solution used in the present invention has a viscosity in the range of 200 mPa · s or less at 40 ° C. under appropriate conditions from the above means, and increases in viscosity as it cools.

  The viscosity of the coating solution used in the present invention is required to be 200 mPa · s or less at the time of coating, which makes it easy to handle and suitable for high-speed coating. In order to dry quickly, a method of blowing a temperature-adjusted wind is efficient and preferable. At this time, for example, the coating liquid is locally moved by the wind, so that the liquid twists and does not form a nonuniform coating film surface. In addition, before the drying step, it is necessary to make the viscosity of the applied coating solution 20 times or more that during coating.

  Here, the viscosity indicates the viscosity measured with a B-type viscometer. Although it is necessary in the present invention to have a viscosity of at least 20 times the viscosity at the time of cooling at 15 ° C., in order to further improve the uniformity of the coating film surface, it is preferably 50 times or more, particularly preferably 100 It is more than double.

〔Base material〕
The base material used in the thermal transfer image-receiving sheet of the present invention has a role of holding the image-receiving layer, and since heat is applied during thermal transfer, it is a material having a mechanical strength that does not hinder handling even in a heated state. Preferably there is.

  Examples of such a base material include condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, coated paper, and cast-coated paper. , Wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, cellulose fiber paper, or polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivatives , Polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether resin Film of phonone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc. A white opaque film formed by adding a white pigment or filler to a synthetic resin can also be used, and is not particularly limited.

  Moreover, the laminated body by the arbitrary combinations of the said base material can also be used. Examples of typical laminates include cellulose fiber paper and synthetic paper, or synthetic paper of cellulose synthetic paper and a plastic film. The thickness of these supports may be arbitrary and is usually about 10 to 300 μm.

  In order to obtain higher image sensitivity and high image quality without density unevenness or white spots, it is preferable to have a layer having fine voids in the substrate. As the layer having fine voids, a plastic film or synthetic paper having fine voids inside can be used. When a plastic film or synthetic paper having fine voids is used, polyolefin, particularly polypropylene, is mainly blended with an inorganic pigment and / or a polymer incompatible with polypropylene, and these are used as void (void) formation initiators. A plastic film or synthetic paper obtained by stretching and forming a mixture of these is preferable. In the case of those mainly composed of polyester or the like, the cushioning property and heat insulation are inferior to those mainly composed of polypropylene due to their viscoelastic or thermal properties, so that the printing sensitivity is inferior and the density unevenness is inferior. Etc. are also likely to occur.

Considering these points, the elastic modulus at 20 ° C. of the plastic film and the synthetic paper is preferably 5 × 10 ⁸ to 1 × 10 ¹⁰ Pa. In addition, since these plastic films and synthetic paper are usually formed by biaxial stretching, they shrink by heating. When these are left at 110 ° C. for 60 seconds, the shrinkage is 0.5 to 2.5%.

  The plastic film or synthetic paper described above may itself be a single layer including a fine void or may have a plurality of layer configurations. In the case of a plurality of layer structures, all the layers constituting the structure may contain fine voids, or a layer containing no fine voids may be contained. The plastic film or synthetic paper may be mixed with a white pigment as a concealing agent as necessary. Further, in order to increase whiteness, an additive such as a fluorescent brightening agent may be included. The layer having fine voids preferably has a thickness of 30 to 80 μm.

Further, if necessary, a resin such as polyvinyl alcohol, polyvinylidene chloride, polyethylene, polypropylene, modified polyolefin, polyethylene terephthalate, polycarbonate, or the like is provided on the surface of the substrate opposite to the side on which the image receiving layer is provided for the purpose of preventing curling. And a layer of synthetic paper. As a bonding method, for example, known lamination methods such as dry lamination, non-solvent (hot melt) lamination, EC lamination method and the like can be used, but preferred methods are dry lamination and non-solvent lamination. Examples of the adhesive suitable for the non-solvent lamination method include Takenate 720L manufactured by Takeda Pharmaceutical Co., Ltd., and examples of the adhesive suitable for dry lamination include Takelac manufactured by Takeda Pharmaceutical Co., Ltd. Examples include A969 / Takenate A-5 (3/1), Polysol PSA SE-1400, Vinylol PSA AV-6200 series, manufactured by Showa High Polymer Co., Ltd., and the like. The amount of these adhesives, from about 1-8 g / m ² on a solids, and preferably from 2 to 6 g / m ^2.

  When laminating a plastic film and synthetic paper as described above, or between them, or various papers and a plastic film or synthetic paper, they can be bonded together with an adhesive layer.

  For the purpose of increasing the adhesive strength between the substrate and the heat insulating layer or the dye receiving layer, it is preferable to subject the surface of the substrate to various primer treatments and corona discharge treatments.

  Among the above-described substrates, the substrate preferably used in the present invention is a resin-coated paper having a thickness of 50 to 300 μm in which both sides or one side of the paper is coated with a plastic resin, and more preferably both sides or one side of the paper. Is a resin-coated paper having a thickness of 50 to 300 μm coated with a polyolefin resin.

  Hereinafter, a resin-coated paper in which both sides or one side of paper which is a particularly preferable support in the present invention is coated with a polyolefin resin will be described.

  Paper used for resin-coated paper is made from wood pulp as a main raw material, and if necessary, paper is made using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp. As wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, and LDP with a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10 to 70% by mass. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

  In paper, for example, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc, and titanium oxide, paper strength enhancers such as starch, polyacrylamide, and polyvinyl alcohol, fluorescent whitening agents, polyethylene Water retaining agents such as glycols, dispersants, softening agents such as quaternary ammonium, and the like can be added as appropriate.

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the sum of the 24 mesh residue and the 42 mesh residue whose fiber length after beating is defined in JIS P 8207 is 30 to 70% is preferred. The 4 mesh residue is preferably 20% or less.

  The basis weight of the paper is preferably 50 to 300 g, and particularly preferably 70 to 250 g. The thickness of the paper is preferably 50 to 300 μm.

The paper can also be given a high smoothness by calendering at the paper making stage or after paper making. The paper density is generally 0.7 to 1.2 g / cm ³ (JIS P 8118). Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P 8143.

  A surface sizing agent may be applied to the paper surface, and the same sizing agent that can be added to the base paper can be used as the surface sizing agent.

  The pH of the paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS P 8113.

  Next, the polyolefin resin that covers both or one side of the paper will be described. Examples of the polyolefin resin used for this purpose include polyethylene, polypropylene, polyisobutylene, and polyethylene. Polyolefins such as copolymers mainly composed of propylene are preferable, and polyethylene is particularly preferable.

  Hereinafter, particularly preferred polyethylene will be described. The polyethylene covering the paper surface and / or the back surface is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used. In particular, the polyolefin layer on the coating layer side is preferably one in which rutile or anatase type titanium oxide is added therein to improve opacity and whiteness. The titanium oxide content is generally 1 to 20%, preferably 2 to 15%, based on the polyolefin. In the polyolefin layer, a highly heat-resistant coloring pigment or fluorescent whitening agent for adjusting the white background can be added.

  Examples of the color pigment include ultramarine blue, bitumen blue, cobalt blue, phthalocyanine blue, manganese blue, cerulean, tungsten blue, molybdenum blue, and anthraquinone blue.

  Examples of the optical brightener include dialkylaminocoumarin, bisdimethylaminostilbene, bismethylaminostilbene, 4-alkoxy-1,8-naphthalenedicarboxylic acid-N-alkylimide, bisbenzoxazolylethylene, dialkylstilbene, etc. Is mentioned.

  When coating both sides of the paper, the amount of polyethylene used on the front and back sides is selected to optimize the curl at low and high humidity after the total thickness of the dye-receiving layer and the back layer are provided. In general, however, the thickness of the polyethylene layer is in the range of 15 to 50 μm on the dye receiving layer side and 10 to 40 μm on the back layer side. The ratio of the polyethylene on the front and back sides is preferably set so as to adjust the curl that changes depending on the type and thickness of the dye-receiving layer, the thickness of the inner paper, etc. / 1-1 / 3.

  Furthermore, the polyethylene-coated paper support preferably has the following properties (1) to (7).

(1) Tensile strength: strength defined by JIS P 8113, preferably 19.6 to 294N in the longitudinal direction and 9.8 to 196N in the lateral direction (2) Tear strength: Defined by JIS P 8116 (3) Compressive elastic modulus: 9.8 kN / cm ² is preferable (4) Opacity: JIS P 8138 The strength is preferably 0.20 to 2.94 N in the longitudinal direction and 0.098 to 2.45 N in the lateral direction. 80% or more, particularly 85 to 98% is preferable when measured by the method defined in (5) Whiteness: L ^* , a ^* , b ^* defined in JIS Z 8727 are L ^* = 80 to 96 ^{, a * = -3~ + 5,} b * = -7~ + 2 is preferably a (6) Clark stiffness: Clark stiffness in the conveying direction of the recording sheet is preferred support is 50~300cm ^3/100 (7) The moisture in the base paper 4% to 10% with respect to the paper is preferably (8) glossiness of providing a dye-receiving layer (75 degree specular gloss) is preferably 10-90%.

  In the thermal transfer image-receiving sheet of the present invention, a method for applying various layers, such as a heat insulating layer, an intermediate layer, and an image-receiving layer, which are appropriately provided on the support, can be appropriately selected from known methods. A preferred method is obtained by coating a coating liquid constituting each layer on a support and drying.

  As the coating method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

(Insulation layer)
The heat insulating layer having a heat insulating function according to the present invention can be provided with the function by various methods. Specific methods using inorganic fine particles and hollow particles will be described below, but the present invention is not limited thereto.

<Inorganic fine particles>
Examples of the inorganic fine particles used for forming the heat insulating layer having open cells according to the present invention include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, and titania (titanium dioxide). , Zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. And white inorganic pigments.

  The inorganic fine particles may be used in a state of being uniformly dispersed in the binder as primary particles, or may be added in a state of being dispersed in the binder by forming secondary agglomerated particles. The latter is more preferable from the viewpoint of achieving the properties and cushioning properties.

  The shape of the inorganic fine particles is not particularly limited in the present invention, and may be any of a spherical shape, a rod shape, a needle shape, a flat plate shape, a bead shape, a hollow shape, or a combination thereof.

  Among the inorganic fine particles listed above, the inorganic fine particles according to the present invention are preferably silica, alumina, titania, or a combination thereof from the viewpoint of cost performance. Moreover, as an average particle diameter of a primary particle, it is preferable that it is 3-100 nm from a viewpoint that it is easy to form a porous structure with a high heat insulation function.

  As the inorganic fine particles, it is particularly preferable to use solid fine particles selected from silica, alumina or alumina hydrate.

  As silica that can be used in the present invention, silica synthesized by an ordinary wet method, colloidal silica, silica synthesized by a gas phase method, or the like is preferably used. Fine-particle silica synthesized by a vapor phase method, and fine-particle silica synthesized by a vapor phase method is preferable because not only a high porosity can be obtained, but also a coarse aggregate is not easily formed when added to a binder. .

  Alumina or alumina hydrate may be crystalline or amorphous, and any shape such as amorphous particles, spherical particles, and acicular particles can be used.

  In the present invention, it is preferable that the fine particle dispersion before the inorganic fine particles are mixed with the below-described binder is in a state of being dispersed to the primary particles.

  The primary particle diameter of the inorganic fine particles is preferably 100 nm or less as described above. For example, in the case of vapor-phase process fine particle silica, the average particle diameter (coating of primary particles of inorganic fine particles dispersed in a primary particle state is applied. The particle diameter in the dispersion state before installation) is preferably 3 to 20 nm, and most preferably 4 to 20 nm.

  Examples of silica synthesized by a gas phase method in which the average particle diameter of primary particles used most preferably is 4 to 20 nm include, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd., Cabotil manufactured by Cabot Corp., Leolosil manufactured by Tokuyama Corp., etc. Is commercially available. The gas phase method fine particle silica can be dispersed to near primary particles relatively easily by sucking and dispersing in water, for example, with a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd.

<Hollow particles>
Examples of the hollow particles used for forming the heat insulating layer having closed cells according to the present invention include, for example, a type in which the liquid inside the particles is volatilized by heating, or a type in which the liquid is already hollow before heating, a type of particles There are known types in which the internal liquid is vaporized and expanded to become hollow, and any type can be used, but from the viewpoint of providing excellent smoothness, other than the type that becomes hollow by vaporization and expansion Is preferably used. The average particle size of the hollow particles used in the present invention is preferably from 0.1 to 5.0 μm, more preferably from 0.3 to 3.0 μm, from the viewpoints of heat insulation function and smoothness. The hollow volume ratio of the hollow particles used in the heat insulating layer according to the present invention is preferably 30% or more. When the hollow volume ratio is less than 30%, the heat insulating function is insufficient and a high print density cannot be obtained. Moreover, it is preferable to mix | blend and use in 1-460 mass parts per 100 mass parts of binder resin which forms the porous layer containing a hollow particle. In the porous layer containing hollow particles, calcium carbonate, talc, kaolin, titanium oxide, inorganic pigments are used to provide concealability and whiteness, and to adjust the texture of the thermal transfer image-receiving sheet. Zinc oxide, other known inorganic pigments and fluorescent brightening agents may be included.

<binder>
Next, the binder used for formation of a heat insulation layer is demonstrated.

  The binder that can be used in the heat insulating layer according to the present invention may be hydrophilic or hydrophobic, or may be a combination thereof. It is preferable that the emulsion resin or a hydrophilic binder.

  In the emulsion resin emulsion-polymerized with a polymer dispersant containing a hydroxyl group that is a hydrophobic binder, the polymer dispersant is particularly preferably polyvinyl alcohol. The minimum film forming temperature (Tg) of the emulsion resin is preferably 20 ° C. or less from the viewpoint of forming a film at room temperature, but more preferably 5 ° C. or less. The average particle size of the emulsion resin is preferably from 0.01 to 2 μm, particularly preferably from 0.05 to 1.5 μm. Examples of such commercially available emulsion resins include vinyl acetate emulsions such as Binizol 480 and Vinizol 2023 manufactured by Daido Chemical Industries, and vinyl acetates such as ViniBran 1108W and ViniBran 1084W manufactured by Nissin Chemical Industry. And emulsions such as vinyl emulsions, vinyl emulsion 2597, vinyl emulsion 2561, and other acrylic emulsions, and vinyl acetate-ethylene emulsions such as Sumikaflex S-400 and Sumikaflex S-405 manufactured by Sumitomo Chemical Co., Ltd.

  Examples of the hydrophilic binder used in the heat insulating layer according to the present invention include gelatin, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, polyacrylic acid and salts thereof, agar , Κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthene gum, locust bean gum, alginic acid, gum arabic, polyalkylenoxide system described in JP-A-7-195826 and 7-9757 Copolymer, water-soluble polyvinyl butyral, or a homopolymer or copolymer of a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260, alone or in combination It used a combination of the above. The hydrophilic binder preferably used in the present invention is polyvinyl alcohol.

  Examples of the polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol having an anionic group, and modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol substituted with a silyl group.

  The polyvinyl alcohol used in combination preferably has an average degree of polymerization of 300 or more, particularly preferably an average degree of polymerization of 1000 to 5000, and a saponification degree of preferably 70 to 100 mol%, preferably 80 to 99. Particularly preferred is 5 mol%.

  When used in combination with other hydrophilic binders or hydrophobic binders, the proportion of the emulsion resin emulsion-polymerized with a polymer dispersant containing a hydroxyl group contained in the binder is preferably 5% by mass or more, preferably 10% by mass. The above is particularly preferable.

  Moreover, a cationic polymer can be used in the heat insulation layer according to the present invention. The cationic polymer is a polymer having a primary to tertiary amine, a quaternary ammonium base, a quaternary phosphonium base or the like in the polymer main chain or side chain.

Examples of the cationic polymer used in the present invention include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin dialkylamine addition polymerization things, diallyl dimethyl ammonium chloride polymer, diallyl dimethyl ammonium chloride-SO ₂ copolymer, polyvinyl imidazole, polyvinyl pyrrolidone, vinyl imidazole copolymers, polyvinyl pyridine, polyamidine, chitosan, cationized starch, vinylbenzyltrimethylammonium chloride polymers , (2-methacryloyloxyethyl) trimethylammonium chloride polymer, dimethyla Roh methacrylate polymer, and the like.

  Moreover, as the cationic polymer that can be used in the present invention, a cationic polymer that hardly swells is preferable, and a cationic polymer obtained by copolymerizing acrylic acid or the like is particularly preferable. Examples of acrylic acids include acrylic acid esters and acrylamides, and butyl acrylate and hydroxyethyl methyl acrylate are more preferable.

  Alternatively, cationic polymers described in Chemical Industry Times, August 15 and 25, 1998, and polymer dye fixing agents described in “Introduction to Polymer Drugs” issued by Sanyo Chemical Industries, Ltd. are examples.

  The weight average molecular weight of the cationic polymer that can be used in the present invention is preferably in the range of 2000 to 500,000, and more preferably in the range of 3000 to 100,000.

  The cationic polymer that can be used in the present invention may be applied and dried after being added to the coating solution, or may be added by impregnating the aqueous solution into the coating film after coating and drying the heat insulating layer. Moreover, after apply | coating a heat insulation layer, the method of adding before drying is also mentioned. As a method of adding the heat insulation layer and before drying, curtain coating, spray coating, and other methods are conceivable.

  Further, when the cationic polymer that can be used in the present invention is added in advance to the coating solution, it may be added not only uniformly to the coating solution but also in the form of forming composite particles together with inorganic fine particles. As a method for preparing composite particles by using inorganic fine particles and a cationic polymer, a method in which a cationic polymer is mixed with inorganic fine particles and adsorbed and coated, a method in which the coated particles are aggregated to obtain higher order composite particles, and further a mixing are performed. And a method of making coarse particles obtained in this way into more uniform composite particles using a disperser.

  The cationic polymer that can be used in the present invention generally has a water-soluble group and thus exhibits water solubility, but may not dissolve in water depending on, for example, the composition of the copolymerization component. Although it is preferable that it is water-soluble from the ease of manufacture, even if it is sparingly soluble in water, it can be dissolved and used using a water-miscible organic solvent.

  Here, the water-miscible organic solvent means alcohols such as methanol, ethanol, isopropanol, and n-propanol, glycols such as ethylene glycol, diethylene glycol, and glycerin, esters such as ethyl acetate and propyl acetate, acetone, and methyl ethyl ketone. An organic solvent that can dissolve approximately 10% or more in water, such as ketones and amides such as N, N-dimethylformamide. In this case, the amount of the organic solvent used is preferably equal to or less than the amount of water used.

The cationic polymer is usually used in an amount of 0.1 to 10 g, preferably 0.2 to 5 g, per 1 m ² of the thermal transfer image receiving sheet.

The amount of the inorganic fine particles described above is generally 3 to 30 g, preferably 5 to 25 g, per 1 m ^{2 of} the thermal transfer image receiving sheet. The ratio of the inorganic fine particles to the binder is 1:10 to 20: 1 by mass ratio, and particularly preferably 1: 8 to 12: 1.

(Middle layer)
In the present invention, it is preferable to provide an intermediate layer between the heat insulating layer and the image receiving layer in addition to the heat insulating layer described above on the substrate.

  Examples of the function of the intermediate layer according to the present invention include solvent resistance performance, barrier performance, adhesion performance, white color imparting ability, hiding performance, antistatic function, etc., but are not limited thereto, and conventionally known intermediate layers All are applicable.

  In order to impart solvent resistance and barrier performance to the intermediate layer, it is preferable to use a water-soluble resin. Examples of water-soluble resins include cellulose resins such as carboxymethylcellulose, polysaccharide resins such as starch, proteins such as casein, gelatin, agar, and polyvinyl alcohol, ethylene vinyl acetate copolymer, polyvinyl acetate, vinyl chloride, Vinyl-based resins such as vinyl acetate copolymers (for example, Veopa manufactured by Japan Epoxy Resin Co., Ltd.), vinyl acetate (meth) acrylic copolymers, (meth) acrylic resins, styrene (meth) acrylic copolymers, and styrene resins. In addition, polyamide resins such as melamine resin, urea resin and benzoguanamine resin, polyester, polyurethane and the like can be mentioned. The water-soluble resin here is completely dissolved (particle size of 0.01 μm or less), colloidal dispersion (0.01 to 0.1 μm), or emulsion (0.1 to 1 μm) in a solvent mainly composed of water. ) Or a resin in a slurry (1 μm or more) state. Among these water-soluble resins, particularly preferred are alcohols such as methanol, ethanol and isopropyl alcohol, and dissolution with general-purpose solvents such as hexane, cyclohexane, acetone, methyl ethyl ketone, xylene, ethyl acetate, butyl acetate and toluene. Of course, it is a resin that does not even swell. In this sense, a resin that is completely soluble in a solvent mainly composed of water is most preferable. In particular, a polyvinyl alcohol resin and a cellulose resin are mentioned.

  In order to give adhesive performance to the intermediate layer, a urethane-based resin or a polyolefin-based resin is generally used, depending on the type of the base sheet and its surface treatment. Further, when a thermoplastic resin having active hydrogen and a curing agent such as an isocyanate compound are used in combination, good adhesiveness can be obtained.

  In order to give the intermediate layer a white color imparting ability, a fluorescent whitening agent can be used. The fluorescent brightening agent used can be any conventionally known compound, including stilbene, distilbene, benzoxazole, styryl-oxazole, pyrene-oxazole, coumarin, aminocoumarin, imidazole, and benzimidazole. -Based, pyrazoline-based, and distyryl-biphenyl-based fluorescent whitening agents. The whiteness can be adjusted by the type and amount of the fluorescent brightener. Any method can be used as the method of adding the optical brightener. That is, a method of adding by dissolving in water, a method of adding by pulverizing and dispersing by a ball mill or a colloid mill, a method of dissolving in a high boiling point solvent and mixing with a hydrophilic colloid solution, and adding as an oil-in-water dispersion, There is a method of impregnating the polymer latex and adding it.

  Furthermore, titanium oxide may be added to the intermediate layer in order to conceal the glare of the base sheet and unevenness. Use of titanium oxide is preferable in that the degree of freedom in selecting a base sheet is widened. There are two types of titanium oxide: rutile type titanium oxide and anatase type titanium oxide, but considering the effect of whiteness and fluorescent brightening agent, the absorption in the ultraviolet region is shorter than rutile type. Anatase type titanium oxide is preferred. If the binder resin in the intermediate layer is aqueous and titanium oxide is difficult to disperse, use titanium oxide with a hydrophilic treatment on the surface, or disperse it with a known dispersant such as a surfactant or ethylene glycol. be able to. As for the addition amount of a titanium oxide, 10-400 mass parts is preferable as a titanium oxide solid content with respect to 100 mass parts of resin solid content.

  In order to impart an antistatic function to the intermediate layer, a conventionally known conductive material such as a conductive inorganic filler or an organic conductive material such as polyaniline sulfonic acid may be appropriately selected and used in accordance with the intermediate layer binder resin. it can. The thickness of such an intermediate layer is preferably set in the range of about 0.1 to 10 μm.

(Image receiving layer)
The binder resin used in the image-receiving layer according to the present invention, the metal ion-containing compound that forms a chelate compound by reacting with a chelate-forming dye, and a release agent will be described in detail below.

<Binder resin>
As the binder resin used in the image-receiving layer according to the present invention, a known binder resin can be used, and a binder (hereinafter also referred to as a dye) that is easily dyed is preferably used. Specifically, polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride and polyvinylidene chloride, vinyl resins such as polyvinyl acetate and polyacrylate, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene Resin, polyamide resin, phenoxy resin, copolymer of olefin such as ethylene or propylene and other vinyl monomers, polyurethane, polycarbonate, acrylic resin, ionomer, cellulose derivative, etc. However, among these, vinyl resins are preferable, and polyester resins, cellulose resins, and polycarbonates are most preferable.

  Further, as the other binder resin, any of the hydrophobic binder described in the description of the heat insulating layer, the hydrophilic binder described below, and a combination thereof may be used.

  Examples of the hydrophilic binder that can be used in combination include gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, hydroxyethyl cellulose, agar, pullulan, dextrin, acrylic acid, carboxymethyl cellulose, casein, and alginic acid. Can also be used together. Among these, a preferred hydrophilic binder is polyvinyl alcohol.

  Examples of the polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol having an anionic group, acetalized polyvinyl acetal resin, and modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol substituted with a silyl group.

  The polyvinyl alcohol used in combination preferably has an average degree of polymerization of 300 or more, particularly preferably an average degree of polymerization of 1000 to 5000, and a saponification degree of preferably 70 to 100 mol%, preferably 80 to 99. Particularly preferred is 5 mol%.

  When other hydrophilic binders or hydrophobic binders are used in combination, the proportion of the emulsion resin emulsion-polymerized with a polymer dispersant containing a hydroxyl group contained in the binder is preferably 5% by mass or more, and 10% by mass. % Or more is particularly preferable.

  Examples of the cationic polymer according to the present invention include the same cationic polymers that can be used in the above-described heat insulating layer.

  The cationic polymer according to the present invention has water solubility because it generally has a water-soluble group, but may not dissolve in water depending on the composition of the copolymerization component, for example. From the viewpoint of ease of production, it is preferable that it is water-soluble, but even if it is sparingly soluble in water, it can be dissolved and used using a water-miscible organic solvent.

  Here, the water-miscible organic solvent means alcohols such as methanol, ethanol, isopropanol, and n-propanol, glycols such as ethylene glycol, diethylene glycol, and glycerin, esters such as ethyl acetate and propyl acetate, acetone, and methyl ethyl ketone. An organic solvent that can dissolve approximately 10% or more in water, such as ketones and amides such as N, N-dimethylformamide. In this case, the amount of the organic solvent used is preferably equal to or less than the amount of water used.

The cationic polymer is usually used in an amount of 0.1 to 10 g, preferably 0.2 to 5 g, per 1 m ^{2 of} the thermal transfer image receiving sheet.

<Metal ion-containing compound that can react with a chelate-forming dye to form a chelate compound>
In the thermal transfer image-receiving sheet of the present invention, a metal ion-containing compound (hereinafter also referred to as a metal source) that can form a chelate compound by reacting with a chelate-forming dye in the receiving layer from the viewpoint of enhancing image storage stability after printing. ) Is preferably contained. Examples of the metal source include inorganic or organic salts of metal ions and metal complexes, both of which are preferably used. Examples of the metal include monovalent and polyvalent metals belonging to Groups I to VIII of the periodic table, among which Al, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Sn, Ti and Zn is preferable, and Ni, Cu, Cr, Co and Zn are particularly preferable.

Specific examples of the metal source include inorganic salts with Ni ²⁺ , Cu ²⁺ , Cr ²⁺ , Co ²⁺ and Zn ²⁺ , aliphatic salts such as acetic acid and stearic acid, or benzoic acid and salicylic acid. Examples include salts of aromatic carboxylic acids.

  In the present invention, the complex represented by the following general formula (I) is particularly preferably used because it can be stably and added to the image receiving layer and is substantially colorless.

Formula (I)
[M (Q ₁ ) _X (Q ₂ ) _Y (Q ₃ ) _Z ] ^{P +} (L ⁻ ) _P
In the above formula, M represents a metal ion, preferably Ni ²⁺ , Cu ²⁺ , Cr ²⁺ , Co ²⁺ , Zn ²⁺ . Q ₁ , Q ₂ , and Q ₃ each represent a coordination compound capable of coordinating with a metal ion represented by M, and may be the same or different from each other. These coordination compounds can be selected from, for example, coordination compounds described in Chelate Science (5) (Nan Edo). L ^- represents an organic anion group, and specific examples thereof include tetraphenyl boron anion and alkylbenzene sulfonate anion. X represents an integer of 1, 2 or 3, Y represents 1, 2 or 0, and Z represents 1 or 0. In these compounds, the complex represented by the above general formula is tetradentate or hexadentate. It is determined by the coordination or by the number of ligands of Q ₁ , Q ₂ and Q ₃ . P represents 1 or 2. Specific examples of this type of metal source include those exemplified in U.S. Pat. No. 4,987,049, compounds 1 to 51 exemplified in JP-A-10-67181, and the like.

The addition amount of the metal source is usually preferably 5 to 80% by mass and more preferably 10 to 70% by mass with respect to the receiving layer binder. Moreover, 0.5-20 g / m < ² > is preferable normally and the addition amount of the metal source compound used for this invention has more preferable 1-15 g / m < ² >.

<Release agent>
The image receiving layer according to the present invention preferably contains a release agent in order to prevent thermal fusion with the ink layer of the thermal transfer ink sheet during printing.

  As the mold release agent, a phosphoric ester plasticizer, a fluorine compound, silicone oil (including reaction curable silicone) and the like can be used, and among these, silicone oil is preferable. As the silicone oil, various modified silicones such as dimethyl silicone can be used. Specifically, amino-modified silicones, epoxy-modified silicones, alcohol-modified silicones, vinyl-modified silicones, urethane-modified silicones, and the like can be blended or polymerized using various reactions. One or more release agents are used. Further, the addition amount of the release agent is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the image receiving layer forming resin. When the range of the addition amount is not satisfied, problems such as fusion between the thermal transfer ink sheet and the image receiving layer of the image receiving sheet or a decrease in printing sensitivity may occur. In addition, you may provide these mold release agents as a mold release layer separately on an image receiving layer, without adding to an image receiving layer.

  In the present invention, it is also a preferred embodiment to use a silicone emulsion release agent. The silicone emulsion release agent refers to an emulsion type silicone release agent obtained by emulsifying silicone oil with various emulsifiers. Preferably, it is an emulsion type silicone release agent of oil emulsion (O / W type), and specific examples include KM786, KM785, KM860A manufactured by Shin-Etsu Chemical Co., Ltd. One or two or more types of emulsion type silicone release agents are used. Moreover, you may use together with other mold release agents, such as a silicone oil type | mold.

  In addition, you may provide these mold release agents as a mold release layer separately on an image receiving layer, without adding to an image receiving layer.

<Surfactant>
In the image receiving layer according to the present invention, it is also a preferable aspect that the image receiving layer contains a silicone-based surfactant.

  As the silicone-based surfactant that can be used in the present invention, known ones can be used. For example, introduced in “Supervising Functional Surfactant / Mitsuo Kakuda, Issued / August 2000, Chapter 6”. What is present can be preferably used. Specific examples include EMALEX SS-5050K and EMALEX SS-5602 manufactured by Nippon Emulsion Co., Ltd.

  In the image receiving layer according to the present invention, it is also a preferable aspect that the image receiving layer contains a fluorosurfactant.

  As the fluorosurfactant that can be used in the present invention, known ones can be used. For example, introduced in “Supervision of Functional Surfactant / Mitsuo Tsunoda, Issued / August 2000, Chapter 5”. What is present can be preferably used. Specifically, Neos Co., Ltd.'s tangent series, Sumitomo 3M Co., Ltd. FC-4430, etc. are mentioned.

  Next, the thermal transfer ink sheet used together with the thermal transfer image receiving sheet of the present invention at the time of image formation will be described.

<Thermal transfer ink sheet>
(Substrate sheet)
As a base material sheet used for the thermal transfer ink sheet, conventionally known materials can be used as the base material sheet of the thermal transfer ink sheet. Specific examples of preferable base sheet are thin papers such as glassine paper, condenser paper, paraffin paper, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ketone, polyether sulfone, and other high heat resistant polyesters. Polypropylene, fluororesin, polycarbonate, cellulose acetate, polyethylene derivatives, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene, ionomer, etc. The thing which was done is mentioned. The thickness of the base sheet can be appropriately selected depending on the material so that the strength, heat resistance and the like are appropriate, but usually a thickness of about 1 to 100 μm is preferably used.

  Moreover, when adhesion with the ink layer formed on the surface of the base sheet is poor, it is preferable to perform primer treatment or corona treatment on the surface.

(Ink layer, pigment)
The ink layer constituting the thermal transfer ink sheet is a heat sublimable color material layer containing at least a pigment and a binder resin. The dye used in the ink layer may be used alone or in combination of two or more.

  Below, a pigment | dye is demonstrated.

  The dye-containing region used in the thermal transfer ink sheet can be two or more dye-containing regions having different hues. For example, the dye-containing region contains a yellow dye, a magenta dye, and a cyan dye. A mode in which a pigment-free region is formed next to these pigment-containing regions, a pigment-containing region is composed of an ink layer containing a black pigment, and a pigment-free region is formed next to the region The embodiment and the dye-containing region are composed of a region containing a yellow dye, a region containing a magenta dye, a region containing a cyan dye, and a region containing a black dye, and these dye-containing regions are followed by a dye-free region. The formed aspect etc. are mentioned.

  The dyes used in the heat sublimation colorant layer are all dyes such as azo, azomethine, methine, anthraquinone, quinophthalone, and naphthoquinone that are used in thermal transfer ink sheets of the conventional heat-sensitive sublimation transfer method. There are no particular restrictions. Specific examples of yellow pigments include Holon Brilliant Yellow 6GL, PTY-52, and Macrolex Yellow 6G. Examples of red pigments include MS Red G, Macrolex Red Violet R, Ceres Red 7B, Samaron Red HBSL, and SK. Rubin SEGL and the like, and as blue pigments, Kayaset Blue 714, Waxoline Blue AP-FW, Holon Brilliant Blue S-R, MS Blue 100, Daito Blue No. 1 etc. are mentioned.

  The heat-diffusible dye capable of forming a chelate is not particularly limited as long as thermal transfer is possible, and various known compounds can be appropriately selected and used. For example, JP-A-59-78893 Cyan dyes, magenta dyes, yellow dyes and the like described in JP-A No. 59-109349, JP-A-4-94974, JP-A-4-97894, and Japanese Patent No. 2856225 can be used. .

  For example, examples of the chelate cyan dye include compounds represented by the following general formula (1).

In the general formula (1), R ₁₁ and R ₁₂ each represent a substituted or unsubstituted aliphatic group, and R ₁₁ and R ₁₂ may be the same or different. Examples of the aliphatic group include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, and the like, and examples of the group that can replace these alkyl groups include a linear or branched alkyl group (for example, a methyl group). Group, ethyl group, i-propyl group, t-butyl group, n-dodecyl group, 1-hexylnonyl group, etc.), cycloalkyl group (for example, cyclopropyl group, cyclohexyl group, bicyclo [2.2.1]) Heptyl group, adamantyl group and the like), alkenyl group (for example, 2-propylene group, oleyl group, etc.), aryl group (for example, phenyl group, ortho-tolyl group, ortho-anisyl group, 1-naphthyl group, 9- Anthranyl group, etc.), heterocyclic groups (for example, 2-tetrahydrofuryl group, 2-thiophenyl group, 4-imidazolyl group, 2-pyridyl group, etc.), Logen atom (eg, fluorine atom, chlorine atom, bromine atom), cyano group, nitro group, hydroxy group, carbonyl group (eg, alkylcarbonyl group such as acetyl group, trifluoroacetyl group, pivaloyl group, benzoyl group, pentane) Fluorobenzoyl group, arylcarbonyl group such as 3,5-di-t-butyl-4-hydroxybenzoyl group), oxycarbonyl group (for example, methoxycarbonyl group, cyclohexyloxycarbonyl group, n-dodecyloxycarbonyl group, etc.) Aryloxycarbonyl groups such as alkoxycarbonyl group, phenoxycarbonyl group, 2,4-di-t-amylphenoxycarbonyl group, 1-naphthyloxycarbonyl group, 2-pyridyloxycarbonyl group, 1-phenylpyrazolyl-5-oxy Carbonyl group Heterocyclic oxycarbonyl group, etc.), carbamoyl group (eg, dimethylcarbamoyl group, alkylcarbamoyl group such as 4- (2,4-di-t-amylphenoxy) butylaminocarbonyl group, phenylcarbamoyl group, 1-naphthylcarbamoyl) Arylcarbamoyl group such as a group), alkoxy group (for example, methoxy group, 2-ethoxyethoxy group, etc.), aryloxy group (for example, phenoxy group, 2,4-di-t-amylphenoxy group, 4- (4- Hydroxyphenylsulfonyl) phenoxy group), heterocyclic oxy group (for example, 4-pyridyloxy group, 2-hexahydropyranyloxy group, etc.), carbonyloxy group (for example, acetyloxy group, trifluoroacetyloxy group, pivaloyloxy) Alkylcarbonyloxy groups such as benzoyl Aryloxy groups such as ruoxy groups and pentafluorobenzoyloxy groups), urethane groups (for example, alkylurethane groups such as N, N-dimethylurethane groups, N-phenylurethane groups, N- (p-cyanophenyl) urethane groups. Aryl urethane groups, etc.), sulfonyloxy groups (for example, methanesulfonyloxy groups, trifluoromethanesulfonyloxy groups, alkylsulfonyloxy groups such as n-dodecanesulfonyloxy groups, benzenesulfonyloxy groups, p-toluenesulfonyloxy groups, etc.) An arylsulfonyl group such as a dimethylamino group, a cyclohexylamino group, an alkylamino group such as an n-dodecylamino group, an anilino group, an arylamino group such as a pt-octylanilino group, etc.) , Sulfonylamino group (eg Methanesulfonylamino group, heptafluoropropanesulfonylamino group, alkylsulfonylamino group such as n-hexadecylsulfonylamino group, p-toluenesulfonylamino group, arylsulfonylamino group such as pentafluorobenzenesulfonylamino, etc.), sulfa Moylamino group (eg, alkylsulfamoylamino group such as N, N-dimethylsulfamoylamino group, arylsulfamoylamino group such as N-phenylsulfamoylamino group), acylamino group (eg, acetyl) Amino groups, alkylcarbonylamino groups such as myristoylamino groups, arylcarbonylamino groups such as benzoylamino groups, etc., ureido groups (eg, alkylureido groups such as N, N-dimethylaminoureido groups, N-phenylureido) , Arylureido groups such as N- (p-cyanophenyl) ureido group), sulfonyl groups (eg, alkylsulfonyl groups such as methanesulfonyl group and trifluoromethanesulfonyl group, arylsulfonyl groups such as p-toluenesulfonyl group, etc.) Sulfamoyl groups (eg, dimethylsulfamoyl groups, alkylsulfamoyl groups such as 4- (2,4-di-t-amylphenoxy) butylaminosulfonyl group, and arylsulfamoyl groups such as phenylsulfamoyl group) Etc.), alkylthio groups (for example, methylthio group, t-octylthio group, etc.), arylthio groups (for example, phenylthio group, etc.), heterocyclic thio groups (for example, 1-phenyltetrazol-5-thio group, 5-methyl-1) , 3,4-oxadiazole-2-thio group and the like.

  Examples of the cycloalkyl group and the alkenyl group are the same as the above substituents. Examples of the alkynyl group include 1-propyne, 2-butyne, 1-hexyne and the like.

As R ₁₁ and R ₁₂ , a group that forms a non-aromatic cyclic structure (eg, pyrrolidine ring, piperidine ring, morpholine ring, etc.) is also preferable.

R ₁₃ is preferably an alkyl group, a cycloalkyl group, an alkoxy group, or an acylamino group among the above substituents. n represents an integer of 0 to 4, and when n is 2 or more, the plurality of R ₁₃ may be the same or different.

R ₁₄ is an alkyl group, and examples thereof include a methyl group, an ethyl group, an i-propyl group, a t-butyl group, an n-dodecyl group, and a 1-hexylnonyl group. R ₁₄ is preferably a secondary or tertiary alkyl group, and preferred examples of the secondary or tertiary alkyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, and a 3-heptyl group. The most preferred substituent for R ₁₄ is an isopropyl group or a tert-butyl group. The alkyl group of R ₁₄ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₅ is an alkyl group, and examples thereof include an n-propyl group, i-propyl group, t-butyl group, n-dodecyl group, 1-hexylnonyl group and the like. R ₁₅ is preferably a secondary or tertiary alkyl group, and preferred examples of the secondary or tertiary alkyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, and a 3-heptyl group. The most preferred substituent for R ₁₅ is an isopropyl group or a tert-butyl group. The alkyl group for R ₁₅ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₆ represents an alkyl group, and examples thereof include n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, isopropyl group, sec-butyl group, tert-butyl group. , 3-heptyl group and the like. Particularly preferred substituents for R ₁₆ are straight-chain alkyl groups having 3 or more carbon atoms, such as n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl. And most preferably an n-propyl group or an n-butyl group. The alkyl group of R ₁₆ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom, and is not substituted with a substituent containing other atoms.

  Moreover, as a chelate yellow pigment | dye, the compound represented by following General formula (2) can be mentioned.

In the general formula (2), examples of each substituent represented by R ₁ and R ₂ include a halogen atom, an alkyl group (an alkyl group having 1 to 12 carbon atoms, an oxygen atom, a nitrogen atom, a sulfur atom). Alternatively, a substituent linked by a carbonyl group may be substituted, or an aryl group, alkenyl group, alkynyl group, hydroxyl group, amino group, nitro group, carboxyl group, cyano group or halogen atom may be substituted. Methyl, isopropyl, t-butyl, trifluoromethyl, methoxymethyl, 2-methanesulfonylethyl, 2-methanesulfonamidoethyl, cyclohexyl, etc.), aryl groups (for example, phenyl, 4-t-butylphenyl, 3 -Groups such as nitrophenyl, 3-acylaminophenyl, 2-methoxyphenyl), cyano group, a Lucoxyl group, aryloxy group, acylamino group, anilino group, ureido group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, sulfonyl group, alkoxycarbonyl group, Examples include a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, a silyloxy group, an aryloxycarbonylamino group, an imide group, a heterocyclic thio group, a phosphonyl group, and an acyl group.

Examples of the alkyl group and aryl group represented by R ₃ include the same alkyl groups and aryl groups represented by R ₁ and R ₂ .

Specific examples of the 5- to 6-membered aromatic ring constituted with two carbon atoms represented by Z ₁ include benzene, pyridine, pyrimidine, triazine, pyrazine, pyridazine, pyrrole, furan, thiophene and pyrazole. , Imidazole, triazole, oxazole, thiazole and the like, and these rings may further form condensed rings with other aromatic rings. These rings may have a substituent, and examples of the substituent include the same substituents represented by R ₁ and R ₂ .

  Moreover, as a chelate magenta pigment | dye, the compound represented by following General formula (3) can be mentioned.

In the general formula (3), X represents at least a bidentate chelate-forming group or group of atoms, and Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocycle. , R ¹ and R ² each represent a hydrogen atom, a halogen atom or a monovalent substituent. n represents 0, 1, 2;

  X is particularly preferably a group represented by the following general formula (4).

In the general formula (4), Z ₂ represents an atomic group necessary for forming an aromatic nitrogen-containing heterocyclic ring substituted with at least one group containing a chelatable nitrogen atom. Specific examples of the ring include pyridine, pyrimidine, thiazole, imidazole and the like. These rings may further form a condensed ring with another carbocycle (such as a benzene ring) or a heterocycle (such as a pyridine ring).

  In the general formula (3), Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocyclic ring, and the ring may further have a substituent, and is condensed. You may have a ring. Specific examples of the ring include 3H-pyrrole ring, oxazole ring, imidazole ring, thiazole ring, 3H-pyrrolidine ring, oxazolidine ring, imidazolidine ring, thiazolidine ring, 3H-indole ring, benzoxazole ring, benzimidazole ring, A benzothiazole ring, a quinoline ring, a pyridine ring, etc. are mentioned. These rings may form a condensed ring with another carbocyclic ring (for example, benzene ring) or a heterocyclic ring (for example, pyridine ring). Examples of substituents on the ring include alkyl groups, aryl groups, heterocyclic groups, acyl groups, amino groups, nitro groups, cyano groups, acylamino groups, alkoxy groups, hydroxy groups, alkoxycarbonyl groups, halogen atoms, etc. The group may be further substituted.

R ¹ and R ² each represent a hydrogen atom, a halogen atom (for example, a fluorine atom, a chlorine atom) or a monovalent substituent, and examples of the monovalent substituent include an alkyl group, an alkoxy group, a cyano group, Examples thereof include an alkoxycarbonyl group, an aryl group, a heterocyclic group, a carbamoyl group, a hydroxy group, an acyl group, and an acylamino group.

  X represents at least a bidentate chelating group or a group of atoms, and may be any compound capable of forming a dye as the general formula (3), for example, 5-pyrazolone, imidazole, pyrazolopyrrole, pyrazolopyrazole, pyra Zoloimidazole, pyrazolotriazole, pyrazolotetrazole, barbituric acid, thiobarbituric acid, rhodanine, hydantoin, thiohydantoin, oxazolone, isoxazolone, indandione, pyrazolidinedione, oxazolidinedione, hydroxypyridone, or pyrazolopyridone are preferred .

(Binder resin)
The ink layer contains a binder resin together with the pigment.

  As the binder resin used in the ink layer, a binder resin used in a heat transfer ink sheet of a conventionally known thermal sublimation transfer method can be used. For example, cellulose, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone Examples thereof include water-soluble polymers such as acrylic resins, methacrylic resins, polystyrene, polycarbonate, polysulfone, polyethersulfone, polyvinyl butyral, polyvinyl acetal, ethyl cellulose, and nitrocellulose. Among these resins, polyvinyl butyral, polyvinyl acetal or cellulose resin having excellent storage stability is preferable.

  Content of the pigment | dye and binder resin in an ink layer is not specifically limited, It is preferable to set suitably from a viewpoint on performance.

  The ink layer can contain various known additives as required in addition to the above-described pigment and binder resin. For example, the ink layer is prepared by applying an ink coating solution prepared by dissolving or dispersing the above-described pigment, binder resin, or other additive in an appropriate solvent on a base sheet by a known means such as a gravure coating method. Then, it can be formed by drying. The thickness of the ink layer can be about 0.1 to 3.0 μm, preferably about 0.3 to 1.5 μm.

(Protective layer)
The thermal transfer ink sheet preferably includes a thermal transfer protective layer. The heat transferable protective layer comprises a transparent resin layer serving as a protective layer covering the surface of an image formed by thermal transfer on an image receiving sheet.

  Examples of the resin forming the protective layer include polyester resins, polystyrene resins, acrylic resins, polyurethane resins, acrylic urethane resins, polycarbonate resins, epoxy-modified resins of these resins, resins obtained by modifying these resins with silicone, and the like. Examples thereof include a mixture of these resins, an ionizing radiation curable resin, and an ultraviolet blocking resin. Preferred resins include polyester resins, polycarbonate resins, epoxy-modified resins, and ionizing radiation curable resins. As the polyester resin, an alicyclic polyester resin in which the diol component and the acid component have one or more alicyclic compounds is preferable. As the polycarbonate resin, an aromatic polycarbonate resin is preferable, and an aromatic polycarbonate resin described in JP-A No. 11-151867 is particularly preferable.

  Epoxy-modified resins include epoxy-modified urethane, epoxy-modified polyethylene, epoxy-modified polyethylene terephthalate, epoxy-modified polyphenyl sulfite, epoxy-modified cellulose, epoxy-modified polypropylene, epoxy-modified polyvinyl chloride, epoxy-modified polycarbonate, epoxy-modified acrylic, and epoxy-modified. Polystyrene, epoxy-modified polymethylmethacrylate, epoxy-modified silicone, copolymer of epoxy-modified polystyrene and epoxy-modified polymethylmethacrylate, copolymer of epoxy-modified acrylic and epoxy-modified polystyrene, copolymer of epoxy-modified acrylic and epoxy-modified silicone Preferably, epoxy-modified acrylic, epoxy-modified polystyrene, epoxy-modified polymethyl methacrylate, An epoxy-modified silicone, more preferably a copolymer of epoxy-modified polystyrene and epoxy-modified polymethyl methacrylate, of copolymers of epoxy-modified acryl and epoxy-modified polystyrene, a copolymer of an epoxy-modified acryl and epoxy-modified silicone.

<Ionizing radiation curable resin>
An ionizing radiation curable resin can be used as the heat transferable protective layer. By containing it in the thermal transferable protective layer, the plasticizer resistance and scratch resistance are particularly excellent. As the ionizing radiation curable resin, known ones can be used. For example, a radically polymerizable polymer or oligomer is crosslinked and cured by irradiation with ionizing radiation, and a photopolymerization initiator is added if necessary, and an electron beam is added. Those obtained by polymerization and crosslinking with ultraviolet rays can be used.

<UV blocking resin>
The main purpose of the protective layer containing the ultraviolet blocking resin is to impart light resistance to the printed material. As the ultraviolet blocking resin, for example, a resin obtained by reacting and bonding a reactive ultraviolet absorber to a thermoplastic resin or the above ionizing radiation curable resin can be used. More specifically, a conventionally known non-reactive organic ultraviolet absorber such as salicylate, benzophenone, benzotriazole, substituted acrylonitrile, nickel chelate or hindered amine is added to an addition polymerizable double bond ( Examples thereof include those in which a reactive group such as a vinyl group, an acryloyl group, a methacryloyl group), an alcoholic hydroxyl group, an amino group, a carboxyl group, an epoxy group, or an isocyanate group is introduced.

  The main protective layer provided in the heat transferable protective layer having a single layer structure or the heat transferable protective layer having a multilayer structure as described above is usually about 0.5 to 10 μm, although it depends on the kind of the resin for forming the protective layer. Form to thickness.

  The heat transferable protective layer is preferably provided on the base sheet via a non-transferable release layer.

  The non-transferable release layer always makes the adhesive force between the base sheet and the non-transferable release layer sufficiently higher than the adhesive force between the non-transferable release layer and the heat transferable protective layer, And for the purpose of making the adhesive force between the non-transfer release layer and the heat transferable protective layer before applying heat higher than that after applying heat, (1) together with the resin binder, the average particle 30 to 80% by mass of inorganic fine particles having a diameter of 40 nm or less, or (2) an alkyl vinyl ether / maleic anhydride copolymer, a derivative thereof, or a mixture thereof in a ratio of 20% by mass or more in total. Or (3) containing an ionomer in a proportion of 20% by mass or more. The non-transferable release layer may contain other additives as necessary.

  Examples of the inorganic fine particles include silica fine particles such as anhydrous silica and colloidal silica, and metal oxides such as tin oxide, zinc oxide, and zinc antimonate. The particle diameter of the inorganic fine particles is preferably 40 nm or less. If the thickness exceeds 40 nm, the unevenness of the surface of the heat transferable protective layer increases due to the unevenness of the surface of the release layer, and as a result, the transparency of the protective layer is lowered, which is not preferable.

  The resin binder to be mixed with the inorganic fine particles is not particularly limited, and any resin that can be mixed can be used. For example, polyvinyl alcohol resins (PVA) of various saponification degrees; polyvinyl acetal resins; polyvinyl butyral resins; acrylic resins; polyamide resins; cellulose resins such as cellulose acetate, alkyl cellulose, carboxymethyl cellulose, hydroxyalkyl cellulose; Examples thereof include resins.

  The blending ratio (inorganic particulate / other blending components) of the inorganic particulates and other blending components mainly composed of a resin binder is preferably in the range of 30/70 or more and 80/20 or less in terms of mass ratio. When the blending ratio is less than 30/70, the effect of the inorganic fine particles becomes insufficient. On the other hand, when the blending ratio exceeds 80/20, the release layer does not become a complete film, and the base sheet and the protective layer are in direct contact with each other.

  Examples of the alkyl vinyl ether / maleic anhydride copolymer or derivatives thereof include those in which the alkyl group of the alkyl vinyl ether portion is a methyl group or an ethyl group, and the maleic anhydride portion is partially or completely alcohol (for example, methanol, ethanol, etc.). , Propanol, isopropanol, butanol, isobutanol and the like) can be used.

  The release layer may be formed only with an alkyl vinyl ether / maleic anhydride copolymer, a derivative thereof, or a mixture thereof, but for the purpose of adjusting the peeling force between the release layer and the protective layer, Further resin or fine particles may be added. In that case, it is desirable that the release layer contains 20% by mass or more of an alkyl vinyl ether / maleic anhydride copolymer, a derivative thereof, or a mixture thereof. When the content is less than 20% by mass, the effect of the alkyl vinyl ether / maleic anhydride copolymer or its derivative cannot be sufficiently obtained.

  The resin or fine particles blended in the alkyl vinyl ether / maleic anhydride copolymer or its derivative is not particularly limited as long as it can be mixed and can provide high film transparency at the time of film formation, and any material can be used. Can do. For example, the above-mentioned inorganic fine particles and resin binders that can be mixed with the inorganic fine particles are preferably used.

  As the ionomer, for example, Surlyn A (manufactured by DuPont), Chemipearl S series (manufactured by Mitsui Petrochemical Co., Ltd.) or the like can be used. Further, for example, the above-mentioned inorganic fine particles, a resin binder that can be mixed with the inorganic fine particles, or other resins and fine particles can be further added to the ionomer.

  In order to form a non-transferable release layer, a coating solution containing any of the above components (1) to (3) in a predetermined blending ratio is prepared, and the coating solution is subjected to a gravure coating method or gravure reverse. It apply | coats on a base material sheet | seat by well-known techniques like a coating method, and dries an application layer. The thickness of the non-transferable release layer is usually about 0.1 to 2 μm after drying.

  The thermal transferable protective layer laminated on the base sheet with or without the non-transferable release layer may have a multilayer structure or a single layer structure. In the case of a multi-layer structure, in addition to the main protective layer, which is the main component for imparting various durability to the image, thermal transfer protection is provided to enhance the adhesion between the heat transfer protective layer and the image receiving surface of the print. An adhesive layer disposed on the outermost surface of the layer, an auxiliary protective layer, and a layer for adding a function other than the original function of the protective layer (for example, an anti-counterfeit layer, a hologram layer, etc.) may be provided. The order of the main protective layer and the other layers is arbitrary, but usually other layers are arranged between the adhesive layer and the main protective layer so that the main protective layer becomes the outermost surface of the image receiving surface after transfer. .

  An adhesive layer may be formed on the outermost surface of the heat transferable protective layer. The adhesive layer may be formed of a resin having good adhesiveness when heated, such as acrylic resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride / vinyl acetate copolymer resin, polyester resin, and polyamide resin. it can. In addition to the above resin, the above-mentioned ionizing radiation curable resin, ultraviolet blocking resin and the like may be mixed as necessary. The thickness of the adhesive layer is usually 0.1 to 5 μm.

  In order to form a thermal transferable protective layer on a non-transferable release layer or a substrate sheet, for example, a protective layer coating solution containing a protective layer forming resin, an adhesive layer coating containing a thermal adhesive resin A coating liquid for forming a liquid and other layers to be added as necessary is prepared in advance, and these are applied in a predetermined order on a non-transferable release layer or a substrate sheet and dried. Each coating solution may be applied by a conventionally known method. Moreover, you may provide an appropriate primer layer between each layer.

<Ultraviolet absorber>
Although it is preferable that at least one layer of the heat transferable protective layer contains an ultraviolet absorber, when the transparent resin layer contains it, the transparent resin layer exists on the outermost surface of the printed matter after the protective layer is transferred. The heat sensitive adhesive layer is particularly preferred because the effect is reduced with time due to the influence of the environment over a long period of time.

  Examples of the ultraviolet absorber include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers. Specific examples thereof include Tinuvin P, Tinuvin 234, Tinuvin 320, Tinuvin 326, Tinuvin 327, and Tinuvin 328. , Tinuvin 312, Tinuvin 315 (above, manufactured by Ciba Geigy), Sumisorb-110, Sumisorb-130, Sumisorb-140, Sumisorb-200, Sumisorb-250, Sumisorb-300, Sumisorb-320, Sumisorb-340, 350 Sumisorb-400 (above, manufactured by Sumitomo Chemical Co., Ltd.), Mark LA-32, Mark LA -36, Mark 1413 (above, manufactured by Adeka Argus Chemical Co., Ltd.) and the like are available from the market and any of them can be used.

  Further, a random copolymer having a Tg of 60 ° C. or higher, preferably 80 ° C. or higher, in which a reactive ultraviolet absorber and an acrylic monomer are randomly copolymerized may be used.

  The above-mentioned reactive ultraviolet absorber is a conventionally known salicylate-based, benzophenone-based, benzotriazole-based, substituted acrylonitrile-based, nickel chelate-based, hindered amine-based non-reactive ultraviolet absorber, for example, vinyl group, acryloyl group, Addition-polymerizable double bonds such as methacryloyl groups, or those having introduced an alcoholic hydroxyl group, amino group, carboxyl group, epoxy group, isocyanate group or the like can be used. Specifically, UVA635L, UVA633L (above, manufactured by BASF Japan Ltd.), PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) and the like can be obtained from the market, and any of them can be used.

  The amount of the reactive ultraviolet absorbent in the random copolymer of the reactive ultraviolet absorbent and the acrylic monomer as described above is in the range of 10 to 90 mass%, preferably 30 to 70 mass%. Moreover, the molecular weight of such a random copolymer can be about 5000-250,000, Preferably it can be about 9000-30000. The above-described ultraviolet absorber and the random copolymer of the reactive ultraviolet absorber and the acrylic monomer may be contained alone or in combination. The addition amount of the random copolymer of the reactive ultraviolet absorber and the acrylic monomer is preferably 5 to 50% by mass with respect to the layer to be contained.

  Of course, other light-proofing agents may be included in addition to the UV absorber. Here, the light fastening agent is an agent that prevents or alters the degradation or decomposition of the dye by absorbing or blocking the action of altering or decomposing the dye, such as light energy, thermal energy, oxidation action, and the like. In addition to the inhibitor, a light stabilizer known as an additive of a synthetic resin or the like can be used. In this case, it may be contained in at least one of the heat transferable protective layers, that is, at least one of the release layer, the transparent resin layer, and the heat-sensitive adhesive layer, but is particularly preferably contained in the heat-sensitive adhesive layer.

  Although the usage-amount of the light-proofing agent containing said ultraviolet absorber is not specifically limited, Preferably it is 0.05-10 mass parts per 100 mass parts of resin which forms the layer to contain, Preferably it is a ratio of 3-10 mass parts Used in. If the amount used is too small, it is difficult to obtain an effect as a light-proofing agent, while if too large, it is uneconomical.

  In addition to the above light-proofing agent, various additives such as a fluorescent brightening agent and a filler can be added to the adhesive layer in an appropriate amount at the same time.

  The transparent resin layer of the protective layer transfer sheet may be provided alone on the substrate sheet, or may be provided in the surface order with the ink layer of the thermal transfer ink sheet.

(Heat resistant slipping layer)
In the thermal transfer ink sheet, it is preferable to provide a heat-resistant slipping layer on the opposite side of the base material sheet from the ink layer.

  The heat resistant slipping layer is provided for the purpose of preventing thermal fusion between a heating device such as a thermal head and a base sheet, smooth running, and removing deposits on the thermal head.

  Examples of the resin used for the heat resistant slipping layer include cellulose resins such as ethyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, nitrocellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl Vinyl resins such as acetal and polyvinyl pyrrolidone, acrylic resins such as polymethyl methacrylate, polyethyl acrylate, polyacrylamide, and acrylonitrile-styrene copolymers, polyimide resins, polyamide resins, polyamideimide resins, polyvinyltoluene resins, polymers A single or mixture of natural or synthetic resin such as malon indene resin, polyester resin, polyurethane resin, silicone modified or fluorine modified urethane is used. It is. In order to further improve the heat resistance of the heat resistant slipping layer, among the above resins, a resin having a hydroxyl group-based reactive group is used, and a polyisocyanate or the like is used in combination as a crosslinking agent. It is preferable to do.

  Further, in order to impart slidability with the thermal head, a solid or liquid release agent or lubricant may be added to the heat-resistant slip layer to provide heat-resistant slip. Examples of the release agent or lubricant include various waxes such as polyethylene wax and paraffin wax, higher aliphatic alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants. Activators, fluorine surfactants, metal soaps, organic carboxylic acids and derivatives thereof, fluorine resins, silicone resins, fine particles of inorganic compounds such as talc, silica, and the like can be used. The amount of the lubricant contained in the heat resistant slipping layer is 5 to 50% by mass, preferably about 10 to 30% by mass. The thickness of such a heat-resistant slipping layer can be about 0.1 to 10 μm, preferably about 0.3 to 5 μm.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “mass%”.

Example 1
<< Preparation of thermal transfer image-receiving sheet >>
[Preparation of Thermal Transfer Image Receiving Sheet 1: Comparative Example]
The thermal transfer image receiving sheet 1 of Example 1 described in the example of Japanese Patent Application No. 2004-140925 was used as the thermal transfer image receiving sheet 1.

[Preparation of Thermal Transfer Image Receiving Sheet 2: Comparative Example]
The thermal transfer image receptor of Example 1 described in Examples of JP-A No. 11-321128 was used as a thermal transfer image receptor sheet 2.

[Preparation of Thermal Transfer Image Receiving Sheet 3: Comparative Example]
The thermal transfer image receptor of Example 1 described in the examples of JP-A-2002-192842 was used as the thermal transfer image receptor sheet 3.

[Preparation of Thermal Transfer Image Receiving Sheet 4: Comparative Example]
As a base sheet, a polyethylene-coated paper in which both sides of a base paper having a thickness of 170 g / m ² are coated with polyethylene (described as RC paper in Table 1, containing 8% anatase-type titanium oxide in polyethylene on the porous layer side) , gelatin undercoating layer of the porous layer side 0.05 g / m ^2, the porous layer and a back layer 0.2 g / m ² containing latex polymer Tg is about 80 ° C. the surface opposite to The following heat insulating layer coating solution 1 and intermediate layer coating solution 1 are applied on one side of the same by using a slide hopper type multilayer coating apparatus, and then by hot air. Drying was performed. Next, the following image receiving layer coating solution 1 was applied thereon by a wire bar coating method and dried at 120 ° C. for 1 minute to prepare a thermal transfer image receiving sheet 4.

(Insulation layer coating solution 1)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 30 parts by weight Boric acid / borax = 1/1 1% solution Amount of coating solution viscosity at 40 ° C to 18 mPa · s Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) , Primary particle diameter 12nm)
20 parts by weight water 20 parts by weight (intermediate layer coating solution 1)
Polyvinyl alcohol (average polymerization degree 3500) 8% solution 30 parts by mass Boric acid / borax = 1/1 1% solution 1 part by mass Anatase-type titanium oxide 10 parts by mass Water 54 parts by mass (Image-receiving layer coating solution 1)
Dry solids polyethylene terephthalate 10 parts by weight of dimethyl silicone 1 part by mass Methyl ethyl ketone / toluene = 1/1 40 parts by an intermediate layer and the image receiving layer, respectively 1.0 g / m ^2, was 4.0 g / m ^2.

[Preparation of Thermal Transfer Image Receiving Sheet 5: Comparative Example]
In the production of the thermal transfer image-receiving sheet 4, a thermal transfer image-receiving sheet 5 was produced in the same manner except that the following thermal insulation layer coating solution 2 was used instead of the thermal insulation layer coating solution 1.

(Insulation layer coating solution 2)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 30 parts by weight Boric acid / borax = 1/1 1% solution Amount of coating solution viscosity at 40 ° C to 250 mPa · s Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) , Primary particle diameter 12nm)
20 parts by weight dry solids of 20 parts by mass of water intermediate layer and the image receiving layer, respectively 1.0 g / m ^2, was 4.0 g / m ^2.

[Preparation of Thermal Transfer Image Receiving Sheet 6: Present Invention]
In the production of the thermal transfer image-receiving sheet 4, a thermal transfer image-receiving sheet 6 was produced in the same manner except that the following thermal insulation layer coating solution 3 was used instead of the thermal insulation layer coating solution 1.

(Insulation layer coating solution 3)
Polyvinyl alcohol (average polymerization degree 3500) 8% solution 30 parts by mass Boric acid / borax = 1/1 1% solution 6 parts by mass Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd., primary particle size 12 nm)
20 parts by mass Water 20 parts by mass The dry solid contents of the heat insulating layer, the intermediate layer, and the image receiving layer were 25 g / m ² , 1.0 g / m ² , and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 7: Present Invention]
In the production of the thermal transfer image receiving sheet 4, the thermal transfer image receiving sheet 7 was similarly used except that the following heat insulating layer coating liquid 6 and intermediate layer coating liquid 2 were used instead of the heat insulating layer coating liquid 1 and the intermediate layer coating liquid 1, respectively. Was made.

(Insulation layer coating solution 6)
Acrylic styrene hollow particles (HP-1055 manufactured by Rohm and Haas)
50 parts by weight Alkali-treated gelatin 3.3 parts by weight Water 17 parts by weight (intermediate layer coating solution 2)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 30 parts by weight Boric acid / borax = 1/1 1% solution 6 parts by weight Anatase-type titanium oxide 10 parts by weight Water 54 parts by weight Drying of the heat insulation layer, intermediate layer and image receiving layer The solid contents were 25 g / m ² , 1.0 g / m ² and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 8: Present Invention]
As a base sheet, a polyethylene-coated paper in which both sides of a base paper having a thickness of 170 g / m ² are coated with polyethylene (described as RC paper in Table 1, containing 8% anatase-type titanium oxide in polyethylene on the porous layer side) , gelatin undercoating layer of the porous layer side 0.05 g / m ^2, the porous layer and a back layer 0.2 g / m ² containing latex polymer Tg is about 80 ° C. the surface opposite to And coating the heat insulating layer coating solution 6, the intermediate layer coating solution 2 and the following image receiving layer coating solution 2 on one side using a slide hopper type multilayer coating apparatus. Then, drying with warm air was performed to prepare a thermal transfer image receiving sheet 8.

(Image-receiving layer coating solution 2)
Water dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34%) 50 parts by weight Acid-treated gelatin 8 parts by weight Fluorosurfactant (Sumitomo 3M FC-4430) 1.2 parts by weight Water 40.8 Mass parts The dry solid contents of the heat insulating layer, the intermediate layer, and the image receiving layer were 25 g / m ² , 1.0 g / m ² , and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 9: Present Invention]
A thermal transfer image receiving sheet 9 was prepared in the same manner as in the production of the thermal transfer image receiving sheet 8 except that the following heat insulating layer coating solution 7 was used instead of the heat insulating layer coating solution 6.

(Insulation layer coating solution 7)
Acrylic styrene hollow particles (HP-1055 manufactured by Rohm and Haas)
125 parts by weight of the alkali-treated gelatin 3.3 mass parts Water 23 mass parts heat insulating layer, dry solids of the intermediate layer and the image receiving layer, respectively ^{25g / m 2, 1.0g / m} 2, 4.0g / m 2 met It was.

[Preparation of Thermal Transfer Image Receiving Sheet 10: Present Invention]
In the production of the thermal transfer image-receiving sheet 9, the thermal transfer image-receiving image 9 was similarly used except that the image-receiving layer coating solution 3 in which 3.5 parts by mass of NiCl ₂ was added to the image-receiving layer coating solution 2 was used instead of the image-receiving layer coating solution 2. Sheet 10 was produced.

Dry solids of the heat insulating layer and the intermediate layer are each 25 g / m ^2, was 1.0 g / m ^2.

[Preparation of Thermal Transfer Image Receiving Sheet 11: Present Invention]
In the production of the thermal transfer image receiving sheet 8, a thermal transfer image receiving sheet 11 was produced in the same manner except that the following heat insulating layer coating solution 8 was used instead of the heat insulating layer coating solution 6.

(Insulation layer coating solution 8)
Acrylic styrene hollow particles (HP-1055 manufactured by Rohm and Haas)
250 parts by weight of the alkali-treated gelatin 3.3 mass parts Water 33 mass parts heat insulating layer, dry solids of the intermediate layer and the image receiving layer, respectively ^{25g / m 2, 1.0g / m} 2, 4.0g / m 2 met It was.

[Preparation of Thermal Transfer Image Receiving Sheet 12: Present Invention]
In the production of the thermal transfer image receiving sheet 8, a thermal transfer image receiving sheet 12 was produced in the same manner except that the following heat insulating layer coating solution 9 was used instead of the heat insulating layer coating solution 6.

(Insulation layer coating solution 9)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 41 parts by weight Boric acid / borax = 1/1 1% solution 8 parts by weight Acrylic styrene-based hollow particles (HP-1055 manufactured by Rohm and Haas)
50 parts by mass Water 60 parts by mass The dry solid contents of the heat insulating layer, the intermediate layer, and the image receiving layer were 25 g / m ² , 1.0 g / m ² , and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 13: Present Invention]
In the production of the thermal transfer image receiving sheet 8, a thermal transfer image receiving sheet 13 was produced in the same manner except that the following heat insulating layer coating solution 10 was used instead of the heat insulating layer coating solution 6.

(Insulation layer coating solution 10)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 41 parts by weight Boric acid / borax = 1/1 1% solution 6 parts by weight Acrylic styrene-based hollow particles (HP-1055 manufactured by Rohm and Haas)
125 parts by mass of water 17 parts by mass The dry solid contents of the heat insulating layer, the intermediate layer and the image receiving layer were 25 g / m ² , 1.0 g / m ² and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 14: Present Invention]
A thermal transfer image receiving sheet 14 was prepared in the same manner as in the production of the thermal transfer image receiving sheet 8 except that the thermal insulation layer coating solution 3 was used instead of the thermal insulation layer coating solution 6.

The dry solid contents of the heat insulation layer, the intermediate layer and the image receiving layer were 25 g / m ² , 1.0 g / m ² and 4.0 g / m ² , respectively.

[Preparation of Thermal Transfer Image Receiving Sheet 15: Present Invention]
In the production of the thermal transfer image receiving sheet 8, a thermal transfer image receiving sheet 15 was produced in the same manner except that the following heat insulating layer coating solution 4 was used instead of the heat insulating layer coating solution 6.

(Insulation layer coating solution 4)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 30 parts by mass Boric acid / borax = 1/1 1% solution Amount of coating solution viscosity at 40 ° C to 54 mPa · s Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) , Primary particle diameter 12nm)
20 parts by weight dry solids of 20 parts by mass of water intermediate layer and the image receiving layer, respectively 1.0 g / m ^2, was 4.0 g / m ^2.

[Preparation of Thermal Transfer Image Receiving Sheet 16: Present Invention]
In the production of the thermal transfer image receiving sheet 8, a thermal transfer image receiving sheet 16 was produced in the same manner except that the following thermal insulation layer coating solution 5 was used instead of the thermal insulation layer coating solution 6.

(Insulation layer coating solution 5)
Polyvinyl alcohol (average degree of polymerization 3500) 8% solution 30 parts by weight Boric acid / borax = 1/1 1% solution Amount of coating solution viscosity at 40 ° C to 60 mPa · s Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) , Primary particle diameter 12nm)
20 parts by weight dry solids of 20 parts by mass of water intermediate layer and the image receiving layer, respectively 1.0 g / m ^2, was 4.0 g / m ^2.

[Preparation of Thermal Transfer Image Receiving Sheet 17: Present Invention]
As a base sheet, a polyethylene-coated paper in which both sides of a base paper having a thickness of 170 g / m ² are coated with polyethylene (described as RC paper in Table 1, containing 8% anatase-type titanium oxide in polyethylene on the porous layer side) , gelatin undercoating layer of the porous layer side 0.05 g / m ^2, the porous layer and a back layer 0.2 g / m ² containing latex polymer Tg is about 80 ° C. the surface opposite to And using the slide hopper type multi-layer coating apparatus on one surface of the heat insulating layer coating liquid 10, the intermediate layer coating liquid 2, the following image receiving layer coating liquid 4 and the following peeling layer coating liquid 1. Then, after four layers were simultaneously applied, drying with warm air was performed to prepare a thermal transfer image receiving sheet 17.

(Image-receiving layer coating solution 4)
Water dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34%) 50 parts by weight Acid-treated gelatin 8 parts by weight Water 40.8 parts by weight (Release layer coating solution 1)
Water dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34%) 50 parts by weight Acid-treated gelatin 8 parts by weight Fluorosurfactant (Sumitomo 3M FC-4430) 1.2 parts by weight Water 40.8 Mass parts The dry solid contents of the heat insulating layer, the intermediate layer, the image receiving layer, and the release layer were 25 g / m ² , 1.0 g / m ² , 4.0 g / m ² , and 0.5 g / m ² , respectively.

  Table 1 summarizes typical configurations of the thermal transfer image-receiving sheets 1 to 17 produced as described above and characteristics of the manufacturing method.

<Evaluation of thermal transfer image-receiving sheet>
The above-described fabrication is carried out on the thermal transfer recording apparatus having a thermal head with a resistor shape of square (main scanning direction length 80 μm × sub-scanning direction length 120 μm), 300 dpi (dpi represents the number of dots per 2.54 cm) line head. The image receiving layer portion of the thermal transfer image receiving sheet and the ink layer of the thermal transfer ink sheet for Olympus CAMEDIA P-400 are set in an overlapping manner, and the applied energy is sequentially increased while being in pressure contact with the thermal head and the platen roll. , Magenta, cyan and neutral (yellow, magenta, and cyan three-color overlapping) step pattern patches are heated from the back side of the ink layer at a feed rate of 2.5 msec / line and a feed length of 85 μm per line. Then, each dye is transferred onto the image receiving layer of the thermal transfer image receiving sheet to form an image. It was.

  The images printed as described above were evaluated according to the following methods.

(Curl characteristics)
The thermal transfer image-receiving sheet prepared above was cut into a 20 cm × 20 cm square, left in an environment of 23 ° C. and 50% RH with the image-receiving layer on the flat plate, and left for 5 hours. The maximum value of the height H from the flat plate was measured, and the curl characteristics were evaluated according to the following criteria.

A: H ≦ 1.0 mm
○: 1.0 mm <H ≦ 3.0 mm
Δ: 3.0 mm <H ≦ 7.0 mm
×: 7.0 mm <H
(sensitivity)
In the above image forming method, image formation was performed while changing the applied energy, applied energy E (mJ / mm ² ) required to obtain a reflection density of 1.0 was measured, and sensitivity was evaluated according to the following criteria. .

A: E ≦ 4.8 mJ / mm ²
○: 4.8 mJ / mm ² <E ≦ 5.2 mJ / mm ²
Δ: 5.2 mJ / mm ² <E ≦ 5.6 mJ / mm ²
×: E> 5.6 mJ / mm ²
(White spot tolerance)
The printed step pattern patch images were visually observed for the occurrence of white spots (white spot failures in solid images), and the white spots resistance was evaluated according to the following criteria.

◎: No white spot failure is observed in the image. ○: Almost no white spot failure is found in the image. △: Small size white spot failure is scattered in the image. ： It is in a practically acceptable range ×: A strong white spot failure has occurred in the image, and this is a quality that causes a practical problem (heat resistance)
The produced thermal transfer image-receiving sheet was stored at a temperature of 75 ° C. for 3 days, and then the above-described image formation was performed. The degree of printing unevenness (white spots) at that time was evaluated in the same manner as the evaluation method for white spot resistance. .

  The results obtained as described above are shown in Table 1.

  As is clear from the results shown in Table 1, the thermal transfer image-receiving sheet of the present invention is superior in curling characteristics and white-out resistance to the comparative example, and maintains high sensitivity and is also storable (heat resistance). It turns out that it is excellent.

  Further, the thermal transfer image receiving sheet 10 was evaluated using a thermal transfer ink sheet for Pe602 manufactured by Konica Minolta Photo Imaging, Inc. instead of the thermal transfer ink sheet for CAMEDIA P-400 manufactured by Olympus. Confirmed that it was excellent.

Claims (8)

  In a thermal transfer image-receiving sheet having at least a heat insulating layer and an image-receiving layer on a substrate, at least one of the layers is formed by a coating method, and the viscosity of 40 ° C. of the coating solution of the layer is 200 mPa · s or less, A thermal transfer image-receiving sheet, wherein the viscosity at 15 ° C is 20 times or more of the viscosity at 40 ° C.   At least two layers are formed by the coating method, and the viscosity of 40 ° C. of the coating liquid of all the layers formed by the coating method is 200 mPa · s or less, and the viscosity of 15 ° C. is 20 times the viscosity of 40 ° C. The thermal transfer image receiving sheet according to claim 1, which is as described above.   The thermal transfer image receiving sheet according to claim 2, wherein at least two layers formed by the coating method are coated simultaneously.   In a thermal transfer image-receiving sheet having at least a heat-insulating layer, an intermediate layer and an image-receiving layer on a substrate, at least the heat-insulating layer and the intermediate layer are formed by a coating method, and the viscosity at 40 ° C. of the coating solution of the layer is 200 mPa · s. The thermal transfer image-receiving sheet according to claim 2, wherein the thermal transfer image-receiving sheet has a viscosity at 15 ° C. of 20 times or more of a viscosity at 40 ° C.   In a method for producing a thermal transfer image-receiving sheet having at least a heat insulating layer and an image-receiving layer on a substrate, at least one of the layers is formed by a coating method, and the viscosity at 40 ° C. of the coating solution of the layer is 200 mPa · s or less. A method for producing a thermal transfer image-receiving sheet, wherein the viscosity at 15 ° C. is 20 times or more of the viscosity at 40 ° C.   At least two layers are formed by a coating method, and the viscosity of 40 ° C. of the coating liquid of all the layers formed by the coating method is 200 mPa · s or less, and the viscosity at 15 ° C. is 20 times the viscosity at 40 ° C. The method for producing a thermal transfer image receiving sheet according to claim 5, which is as described above.   The method for producing a thermal transfer image receiving sheet according to claim 6, wherein at least two layers formed by the coating method are coated simultaneously.   In a method for producing a thermal transfer image-receiving sheet having at least a heat insulating layer, an intermediate layer and an image receiving layer on a substrate, at least the heat insulating layer and the intermediate layer are formed by a coating method, and the coating solution of the layer has a viscosity of 40 ° C. The method for producing a thermal transfer image-receiving sheet according to claim 6 or 7, wherein the viscosity is 200 mPa · s or less, and the viscosity at 15 ° C is 20 times or more of the viscosity at 40 ° C.