JP4883423B2 - Thermal transfer image receiving sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a novel thermal transfer image-receiving sheet that is used by being superposed on a thermal transfer ink 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 an image receiving layer of a thermal transfer image receiving sheet, and thermal printing such as a thermal head or a laser is performed. A technique for forming an image (so-called dye thermal transfer system) by transferring the heat diffusible dye to the image receiving layer like an image using a means is known. Such a thermal transfer method 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 heat history of the manufacturing process and the study of newly devising a functional layer having a heat insulating and cushioning function for such drawbacks, thermal transfer image receiving without a bonding process such as a foam film Various studies have been made on sheets and manufacturing methods such as coating methods.

  For example, by applying a water-based intermediate layer containing hollow particles and an aqueous image-receiving layer containing a release agent adjacent thereto by a wet-on-wet method, the drying energy efficiency during production, and the image-receiving layer and the intermediate layer And a manufacturing method for supplying a thermal transfer image-receiving sheet excellent in blocking resistance with an ink donor sheet is disclosed (for example, see Patent Document 1).

  However, as a result of further testing of the method described in Patent Document 1 by the present inventors, it has been found that the following problems occur. First of all, in the recent increase in printing speed, the technique proposed in Patent Document 1 has insufficient sensitivity. This is presumably because the dye transferred from the thermal transfer ink sheet usually has a strong oil-solubility tendency and is difficult to be dyed on an image receiving layer formed of a hydrophilic binder. For this reason, when the image receiving layer is formed by an aqueous coating method, the smoothness of the surface of the image receiving layer is very important, and it seems that high coating accuracy is required. However, the technique proposed in Patent Document 1 has smoothness. Defects such as white spots are also likely to occur. When a structure having a relatively low specific gravity such as hollow particles is applied, the image receiving layer is applied even if the image receiving layer is applied in a wet state after the intermediate layer is applied as in the method proposed above. The hollow particles are likely to be lifted on the surface of the intermediate layer before, and the surface smoothness tends to be disturbed. In the configuration in which the intermediate layer and the image receiving layer are adjacent to each other, the smoothness of the intermediate layer directly affects the smoothness of the image receiving layer, and as a result, problems such as white spots during printing may occur. Secondly, there is a problem of robustness of interlayer adhesion between the intermediate layer and the image receiving layer as an effect in Patent Document 1. In a high-speed printing machine, dyeing and rapid release after that must be achieved in a short time, but if the release property is adjusted to a level that can cope with this, the amount of release agent added to the image receiving layer is increased. Inevitably, there is a drawback of affecting the interlayer adhesion between the intermediate layer and the image receiving layer. Third, there is a problem of deterioration of image storage. In light of the trend toward higher sensitivity, the molecular weight of dyes used has also progressed, and it has become important to suppress dye migration under high-temperature or high-humidity environments after printing. However, this method does not have a measure that clearly intends its role, and has a drawback that density lowering or bleeding occurs in a high-temperature or high-humidity environment after printing. Fourthly, in the wet-on-wet coating method, although the efficiency of the drying energy can be surely achieved, the number of coatings itself has not changed, and it must be said that it is halfway from the viewpoint of productivity.

JP-A-6-171240

  The present invention has been made in view of the above problems, and its purpose is that even when used in a high-speed printing printer, it has excellent interlayer adhesion, and a homogeneous image without white spots failure can be obtained without impairing sensitivity. It is to provide a thermal transfer image-receiving sheet excellent in image storability and a method for producing the same, and further, production of a thermal transfer image-receiving sheet excellent in production efficiency without deterioration of curling characteristics due to a thermal history during the manufacturing process. Provide a method.

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

(Claim 1)
In the thermal transfer image receiving sheet having a heat insulating layer and an image receiving layer on a substrate, and having an intermediate layer between the heat insulating layer and the image receiving layer, at least all layers constituting the image receiving layer from the heat insulating layer are water-based coating methods A thermal transfer image-receiving sheet formed by the method described above.

(Claim 2)
2. The thermal transfer image receiving sheet according to claim 1, wherein all layers constituting the surface side having the image receiving layer of the substrate are formed by an aqueous coating method. 3.

(Claim 3)
The thermal transfer image receiving sheet according to claim 1 or 2, wherein at least one set of two layers adjacent to each other is formed by simultaneous multilayer coating.

(Claim 4)
The thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein all layers constituting the surface side having the image-receiving layer of the substrate are formed by simultaneous multilayer coating.

(Claim 5)
The thermal transfer image-receiving sheet according to any one of claims 1 to 4, wherein the image-receiving layer contains a metal ion-containing compound that can react with a chelate-forming dye to form a chelate compound.

(Claim 6)
The thermal transfer image-receiving sheet according to claim 1, wherein the image-receiving layer contains a release agent.

(Claim 7)
A dye in which the image receiving layer is composed of two or more layers, the image receiving layer located farthest from the substrate contains a releasing agent, and any one of the other image receiving layers is capable of chelating. The thermal transfer image-receiving sheet according to any one of claims 1 to 4, further comprising a metal ion-containing compound capable of reacting with the compound to form a chelate compound.

(Claim 8)
The thermal transfer image receiving sheet according to any one of claims 1 to 7, wherein the substrate is a resin-coated paper having a thickness of 50 to 250 µm.

(Claim 9)
In the method for producing a thermal transfer image receiving sheet having a heat insulating layer and an image receiving layer on a substrate, and having an intermediate layer between the heat insulating layer and the image receiving layer, at least all layers constituting the image receiving layer from the heat insulating layer are: A method for producing a thermal transfer image receiving sheet, wherein the thermal transfer image receiving sheet is formed by an aqueous coating method.

(Claim 10)
The method for producing a thermal transfer image receiving sheet according to claim 9, wherein all layers constituting the surface side having the image receiving layer of the substrate are formed by an aqueous coating method.

(Claim 11)
The method for producing a thermal transfer image receiving sheet according to claim 9 or 10, wherein at least one set of two layers adjacent to each other is formed by simultaneous multilayer coating.

(Claim 12)
The method for producing a thermal transfer image receiving sheet according to any one of claims 9 to 11, wherein all layers constituting the surface side having the image receiving layer of the substrate are formed by simultaneous multilayer coating.

(Claim 13)
The method for producing a thermal transfer image receiving sheet according to any one of claims 9 to 12, further comprising a coating film cooling and setting step between the coating step and the drying step.

(Claim 14)
The method for producing a thermal transfer image receiving sheet according to any one of claims 9 to 13, wherein an aging treatment is performed after the drying step.

(Claim 15)
When simultaneously applying at least two layers, the viscosity of the coating solution for forming the lowermost layer is η ₁ , and the viscosity of the coating solution for the constituent layers excluding the lowermost layer is η ₂ , the condition of η ₂ > η ₁ is satisfied The method for producing a thermal transfer image receiving sheet according to any one of claims 9 to 14.

(Claim 16)
The method for producing a thermal transfer image-receiving sheet according to any one of claims 9 to 15, wherein the conditions defined by the following formulas (1) and (2) are simultaneously satisfied when at least two layers are applied simultaneously. .

Formula (1)
Ts (L) ≧ Ts (U)
Formula (2)
Td (L) ≧ Td (U)
Where
Ts (L): Static surface tension of the coating solution constituting the relatively lower layer in the simultaneous application Ts (U): The coating solution constituting the relatively upper layer in the simultaneous application Static surface tension Td (L): Dynamic surface tension of a coating solution constituting a relatively lower layer in simultaneous application Td (U): Constructing a relatively upper layer in simultaneous application It represents the dynamic surface tension of the coating liquid.

  According to the present invention, even when used in a high-speed printing printer, a thermal transfer image-receiving sheet excellent in interlayer adhesion, capable of obtaining a homogeneous image free from whiteout failure without impairing sensitivity, and excellent in image storability, and It is to provide a manufacturing method thereof, and further, it is possible to provide a manufacturing method of a thermal transfer image-receiving sheet excellent in production efficiency without deterioration of curling characteristics due to a thermal history during the manufacturing process.

  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 present inventors have a thermal transfer image receiving sheet having a heat insulating layer and an image receiving layer on a substrate, and an intermediate layer between the heat insulating layer and the image receiving layer. A thermal transfer image-receiving sheet in which at least all layers constituting the image-receiving layer from the heat-insulating layer are formed by a water-based coating method. Even when used in high-speed printing printers, it has excellent interlayer adhesion and does not suffer from whiteout failure without losing sensitivity. In addition, the present inventors have found that a thermal transfer image-receiving sheet excellent in production efficiency can be realized without deterioration of curl characteristics due to thermal history during the manufacturing process, and excellent image storage stability. It depends on you.

  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 a heat insulating layer and an image-receiving layer on a substrate, an intermediate layer between the heat-insulating layer and the image-receiving layer, and at least all layers constituting the image-receiving layer from the heat-insulating layer Is formed by an aqueous coating method.

〔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 heat is applied at the time of thermal transfer. Therefore, the base material is a material having a mechanical strength that does not hinder handling even in an overheated 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 mon And films such as chlorofluorocarbon, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride. A white opaque film formed by adding a white pigment or a filler to the synthetic resin can 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.

  In the present invention, the thickness of the substrate is preferably 50 to 250 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. If these are mainly polyester, etc., the viscoelastic or thermal properties make the cushioning and heat insulation properties inferior to those mainly made of polypropylene. Unevenness is 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 Pa to 1 × 10 ¹⁰ Pa. Moreover, 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 above-described plastic film and synthetic paper may be a single layer of a layer containing fine voids or may have a plurality of layers. In the case of a plurality of layer configurations, all layers constituting the layer may contain fine voids, or a layer having no fine voids may be contained. A white pigment may be mixed in the plastic film or synthetic paper as a concealing agent as necessary. In order to increase whiteness, an additive such as a fluorescent brightener 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. Or 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 the plastic film and the synthetic paper as described above, or between them, or various papers and the plastic film or the synthetic paper are laminated, they can be bonded together by an adhesive layer.

  For the purpose of increasing the adhesive strength between the substrate and the intermediate layer or the dye image-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 250 μm, in which both sides of the paper are coated with a plastic resin, and more preferably, both sides of the paper are made of polyolefin resin. This is a resin-coated paper having a thickness of 50 to 250 μm.

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

  The paper used in the resin-coated paper according to the present invention is made from wood pulp as a main raw material and, if necessary, paper making 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 short fiber content. However, the ratio of LBSP and / or LDP is preferably 10 to 70%. 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 250 g, particularly preferably 70 to 200 g. The thickness of the paper is preferably 50 to 250 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 the hot water extraction method specified in JIS P8113.

  Next, the polyolefin resin that covers both sides 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 the back surface is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can also be used in part.

  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.

  The amount of polyethylene used on the front and back of the paper is selected so as to optimize the curl at low and high humidity after the film thickness and the back layer on the dye image-receiving layer side are provided. The thickness of the layer ranges from 15 to 50 μm on the dye image-receiving layer side and from 10 to 40 μm on the back layer side. The ratio of polyethylene on the front and back is preferably set so as to adjust the curl that changes depending on the type and thickness of the dye image-receiving layer, the thickness of the inner paper, etc. 3/1 to 1/3.

  Further, 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) Compression modulus: 9.8 kN / cm ² is preferable (4) Opacity: JIS P 8138 80% or more, especially 85 to 98% is preferable when measured by the method defined in (5) Whiteness: L ^* , a ^* and 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) In the base paper The water content is preferably 4 to 10% with respect to the inner paper. (8) The glossiness (75 degree specular glossiness) for providing the dye image-receiving layer is preferably 10 to 90%.

  In the thermal transfer image-receiving sheet of the present invention, a method for applying various layers, such as a porous layer and an undercoat 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. In this case, two or more layers can be applied at the same time. In particular, simultaneous application in which all the hydrophilic binder layers need only be applied once is preferable.

  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. For example, there is a method of adding inorganic fine particles.

  Examples of the inorganic fine particles include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titania (titanium dioxide), zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, Examples thereof include white inorganic pigments such as hydrotalcite, aluminum silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide.

  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 high heat insulation 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 irregular particles, spherical particles, acicular particles, hollow particles may be used. it can.

  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 the inorganic fine particles dispersed in the 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 vapor phase fine particle silica can be dispersed to near primary particles relatively easily by sucking and dispersing in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd.

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

  Moreover, when forming the heat insulation layer using this means, the porosity of the heat insulation layer is preferably adjusted to 40% or more, and more preferably adjusted to a range of 40 to 95%. If the porosity is less than 40%, the function of heat insulation / cushion is not sufficiently exhibited, and if it exceeds 95%, the heat insulation effect does not increase and the mechanical strength deteriorates. The porosity here is a ratio of the total volume of the voids in the volume of the heat insulating layer, and can be calculated from the total volume of the constituents of the layer and the thickness of the layer. The porosity can be appropriately adjusted depending on the type of inorganic fine particles and binder to be selected or the amount of other additives.

  As another method for providing a heat insulating function, a method containing hollow particles is also preferably used. The particle size of the hollow particles used in the present invention is preferably 0.1 to 60 μm. When the particle size of the hollow particles is less than 0.1 μm, a sufficient heat insulating function and cushion function cannot be obtained, and when it exceeds 60 μm, the smoothness of the contained layer is hindered and the image quality is deteriorated. Especially preferably, it is the range of 0.3 micrometer-20 micrometers. Further, the volumetric hollow ratio of the hollow particles is preferably 40% or more, and if it is less than this, sufficient heat insulation and cushioning effects cannot be obtained. A hollow ratio of 50% or more is particularly preferable. From the viewpoint of increasing the stability in the coating solution, it is also a preferred method to increase the specific gravity by coating the surface of the hollow particles with an inorganic pigment or the like. As the inorganic pigment, all the inorganic fine particles mentioned above are used, and the hollow particles can be coated by means such as heat fusion. As the hollow particles, for example, a low boiling point liquid such as butane or pentane is microencapsulated with a resin or copolymer such as polyvinylidene chloride, polyacrylonitrile, or methyl methacrylate. In the present invention, there are a method of adding pre-foamed particles and a method of adding unfoamed particles. In the latter case, uniform foaming is performed by foaming with heat at the time of thermal transfer image-receiving sheet preparation or printing. Is difficult, and the image quality is deteriorated. Therefore, a method of adding previously expanded particles is preferable. The content of the hollow particles is preferably 10 to 90% by mass. If it is less than 10% by mass, sufficient heat insulation and cushioning effects cannot be obtained, and even if it exceeds 90% by mass, there is no effect in improving these functions. In particular, the content is preferably 20 to 85% by mass.

  As yet another method for imparting a heat insulating function, for example, a method of foaming a coating solution as disclosed in JP-A-11-301124 by physical means such as mechanical stirring is used.

Any of the above methods may be used, but the most important thing as the function of the heat insulating layer is to have heat insulation for obtaining good sensitivity and adhesion at the time of transfer with the thermal transfer ink sheet, From this viewpoint, it is important that the thermal conductivity of the entire thermal transfer image-receiving sheet is 0.35 W / mK or less and the cushion deformation rate is 5 to 60%. The thermal conductivity here means the amount of heat that flows in 1 ^second through 1 m ^{2 of the} plate when there is a temperature difference of 1 ° C. at both ends of the 1 m thick plate, and the cushion deformation rate here is How much the difference between the thickness when a load of 100 g is applied to the image-receiving sheet conditioned at 23 ° C. and 55% RH and when it is not added is changed relative to the thickness when it is not added at all Is a value indicating

  The binder used in the heat insulating layer according to the present invention is preferably a hydrophilic binder described later.

(Middle layer)
In the thermal transfer image receiving sheet of the present invention, providing at least one intermediate layer between the heat insulating layer and the image receiving layer is an important configuration particularly from the viewpoint of improving image storage stability.

  The functions of the intermediate layer according to the present invention include solvent resistance, dye diffusion barrier during image storage under high temperature / high humidity, interlayer adhesion, whitening, glare / unevenness of the substrate, antistatic, etc. Although not limited thereto, conventionally known intermediate layer forming means can be applied.

  The binder used for the intermediate layer according to the present invention is preferably a hydrophilic binder described later.

  In the intermediate layer according to the present invention, a fluorescent whitening agent can be used for imparting white. Examples of fluorescent brighteners that can be used include stilbene, distilbene, benzoxazole, styryl-oxazole, pyrene-oxazole, coumarin, aminocoumarin, imidazole, benzimidazole, pyrazoline, Conventionally known fluorescent whitening agents such as a distyryl-biphenyl type may be mentioned. In addition, whiteness can be adjusted with the kind and addition amount of these fluorescent whitening agents.

  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 with a ball mill, 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 in order to conceal the glare of the base sheet and unevenness. Furthermore, the 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. When titanium oxide is difficult to disperse, titanium oxide having a hydrophilic treatment on the surface can be used, or it can be dispersed with a known dispersant such as a surfactant or ethylene glycol. 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 the intermediate layer according to the present invention, in order to provide an antistatic function, a conventionally known conductive material such as a conductive filler or an organic conductive material such as polyaniline sulfonic acid is appropriately selected and used in accordance with the intermediate layer binder resin. can do. The thickness of the intermediate layer according to the present invention is preferably set in the range of about 0.1 to 10 μm.

  Furthermore, when the heat insulating layer is formed by adding inorganic fine particles or mechanically stirring the coating solution to form a porous heat insulating layer, the void portion of the heat insulating layer is concealed to prevent moisture resistance. From the viewpoint of enhancing the properties and obtaining higher printing sensitivity, fine particles such as hollow resin particles can be added to the intermediate layer. The hollow resin fine particles may be used alone or in combination with the aforementioned titanium oxide or the like.

(Image receiving layer)
The image-receiving layer according to the present invention contains a metal ion-containing compound or a releasing agent that reacts with a chelate-forming dye to form a chelate compound, so that image preservability or dye thermal transfer from an ink-donating sheet is included. It is preferable in terms of later release properties.

  Hereinafter, 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 the release agent will be described in detail.

<Binder resin>
In the thermal transfer image-receiving sheet of the present invention, the heat insulating layer, the intermediate layer, and the image-receiving layer are characterized by being formed by an aqueous coating method, and the binder used in the layer is preferably a hydrophilic binder, A dispersible hydrophobic polymer or the like can also be preferably used. Regarding the layers other than the above layers, the binder may be hydrophilic, hydrophobic, or a mixture thereof.

  Examples of the hydrophobic binder include polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, ethylene and the like. Examples thereof include copolymer resins of olefins such as propylene and other vinyl monomers, cellulose resins such as ionomers and cellulose diacetates, and polycarbonate resins, with vinyl resins and polyester resins being preferred. These resins can be used alone or in combination.

  Examples of the hydrophilic binder used in the heat insulating layer, intermediate layer, and image receiving layer according to the present invention include gelatin, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, and polyacrylic acid. And salts thereof, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthene gum, locust bean gum, alginic acid, gum arabic, and those described in JP-A-7-195826 and 7-9757. A homopolymer or copolymer of a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260, or a real xylene oxide copolymer, water-soluble polyvinyl butyral, or the like. Rui is used in combination of two or more. The hydrophilic binder preferably used in the present invention is polyvinyl alcohol.

  As the gelatin, all those obtained by various production methods such as lime treatment or acid treatment can be used, and among them, the use of acid-treated gelatin is preferable from the viewpoint of further improving interlayer adhesion.

  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.

  Next, the above-mentioned cationic polymer that can be used in the present invention will be described.

  The cationic polymer that can be used in the present invention is a polymer having a primary to tertiary amine, a quaternary ammonium base, or a quaternary phosphonium base 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 and 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 And minoethyl methacrylate polymer.

  Moreover, as the cationic polymer according to the present invention, a cationic polymer that hardly swells is preferable, and a cationic polymer copolymerized with acrylic acid or the like is particularly preferable. Examples of acrylic acids include acrylic esters and acrylamides, and butyl acrylate and hydroxyethyl methyl acrylate are more preferable.

  Alternatively, the cationic dye described in the Chemical Industry Times, August 15 and 25, 1998, and the polymer dye fixing agent described in “Introduction to Polymer Drugs” issued by Sanyo Chemical Industries, Ltd. can be given as examples.

  The weight average molecular weight of the cationic polymer according to 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 according to the present invention may be applied and dried after being added to the coating solution, or may be added by impregnating the coating film after applying and drying the image receiving layer as an aqueous solution.

  In addition, when the cationic polymer according to 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 according to the present invention generally has water-solubility because it has a water-soluble group, but may not dissolve in water depending on, for example, the composition of the copolymer 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.

<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) capable of reacting with a chelate-forming dye contained in the image-receiving layer to form a chelate compound is an inorganic metal ion or An organic salt and a metal complex are mentioned, and among them, an inorganic salt is preferable. Examples of the metal include monovalent and polyvalent metals belonging to Groups I to VIII of the Periodic Table. Among them, Al, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Sn, i And Zn are preferable, and Ni, Cu, Cr, Co and Zn are particularly preferable.

Specific examples of metal sources 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 aromatic carboxylic acids such as benzoic acid and salicylic acid. Examples include salts.

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.
The complex represented by the following general formula (I) is particularly preferably used because it can be stably and added to the dye 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 coordination 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 a tetraphenyl boron anion and an 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 depending on whether it is coordinated or determined based on 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 US 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 image 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>
In the image receiving layer according to the present invention, in order to prevent thermal fusion with the ink layer of the thermal transfer ink sheet at the time of printing, one feature is that it contains a release agent. An emulsion type or water-soluble type release agent is preferred.

  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. These releasing agents may not be added to the image receiving layer, but may be provided separately as a releasing layer on the image receiving layer.

  In the present invention, it is preferable to use a silicone-based emulsion-type release agent. The silicone-based emulsion-type release agent is an emulsion-type silicone release agent obtained by emulsifying silicone oil with various emulsifiers. That means. 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.

  These releasing agents may not be added to the image receiving layer, but may be provided separately as a releasing layer on the image receiving layer.

<Silicone surfactant>
In the image receiving layer according to the present invention, the image receiving layer preferably 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.

<Fluorosurfactant>
In the image receiving layer according to the present invention, the image receiving layer preferably 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.

  In the thermal transfer image-receiving sheet of the present invention, the image-receiving layer is composed of two or more layers, the image-receiving layer farthest from the substrate contains a release agent, and any one of the other image-receiving layers The layer preferably contains a metal ion-containing compound that can form a chelate compound by reacting with a chelate-forming dye as an optimum functional configuration of image preservability and releasability.

<Hardener>
In the thermal transfer image-receiving sheet of the present invention, it is preferable that at least one of the layers formed by the aqueous coating method contains a hardener. The hardener can be added in any of the coating liquid preparation step and the coating step for producing the thermal transfer image-receiving sheet.

  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, but other known ones are also known. In general, it is a compound having a group that can react with a hydrophilic binder or a compound that promotes the reaction between different groups of the hydrophilic binder, and is appropriately selected according to the type of the binder. 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 in 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 total amount of the hardener used is preferably 1 to 1000 mg per 1 g of the binder. Moreover, as supply_amount | feed_rate with respect to a binder, 100-1000 mg per 1g of said binders is preferable.

<Image-receiving layer coating solution pH>
The pH of the image-receiving layer coating solution for forming the image-receiving layer according to the present invention is preferably 8.0 or less from the viewpoint of further exerting the object effect of the present invention, and more preferably 5.0 to 8.0. It is.

[Coating method]
In the method for producing a thermal transfer image-receiving sheet of the present invention, at least all layers constituting the image-receiving layer from the heat insulating layer are formed by an aqueous coating method, but other constituent layers that are appropriately provided as necessary Can be formed by appropriately selecting from known coating methods.

  Moreover, in the manufacturing method of the thermal transfer image receiving sheet of this invention, it is preferable to form all the layers which comprise the surface side which has an image receiving layer of a base material with a water-system coating system.

  In addition, it is preferable to form at least one pair of two layers adjacent to each other by simultaneous multilayer coating, and further, to form all layers constituting the surface side of the substrate having the image receiving layer by simultaneous multilayer coating. Is preferred.

  By adopting the coating form defined above, a coating film having high uniformity and excellent smoothness can be formed.

  The coating method that can be used in the present invention is not particularly limited. For example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or US Pat. No. 2,681,294. The extrusion coating method using the described hopper is preferably used.

In the method for producing a thermal transfer image-receiving sheet of the present invention, when at least two layers are applied simultaneously, the coating solution viscosity for forming the bottom layer is η ₁ , and the coating solution viscosity of the constituent layers excluding the bottom layer is η ₂ . At this time, it is preferable that the coating is performed under a condition satisfying the relationship of η ₂ > η ₁ in terms of forming a uniform and homogeneous coating film.

Under the conditions specified above, the difference in viscosity between η ₂ and η ₁ is at least 2 mPa · s, preferably 5 mPa · s or more, when the coating solution temperature is 40 ° C. The absolute value of the coating solution viscosity is preferably 100 mPa · s or less in the lowermost layer, and 15 mPa · s or more and 500 mPa · s or less in the other layers. The coating solution temperature is preferably 25 ° C. to 90 ° C., more preferably 30 ° C. to 80 ° C.

  In the present invention, as a method for achieving the viscosity conditions defined above, for example, the viscosity of each coating solution is increased by increasing the water solubility of a conventionally known thickener, for example, styrene and a maleic acid sodium salt copolymer as main components. It can be easily adjusted by adding a sticky agent or an inorganic salt within a range not affecting other performance.

  In the method for producing a thermal transfer image-receiving sheet of the present invention, when at least two layers are applied simultaneously, it is uniform that the application is performed under the conditions satisfying the relations defined by the following formulas (1) and (2) at the same time. From the viewpoint of forming a uniform coating film.

Formula (1)
Ts (L) ≧ Ts (U)
Formula (2)
Td (L) ≧ Td (U)
Where
Ts (L): Static surface tension of the coating solution constituting the relatively lower layer in the simultaneous application Ts (U): The coating solution constituting the relatively upper layer in the simultaneous application Static surface tension Td (L): Dynamic surface tension of a coating solution constituting a relatively lower layer in simultaneous application Td (U): Constructing a relatively upper layer in simultaneous application It represents the dynamic surface tension of the coating liquid.

  The value of Ts (L) is preferably equal to or greater than the value of Ts (U), and when the temperature of the coating solution is 40 ° C., the difference between the two is more preferably 2 mN / m or more. Further, the value of Td (L) is preferably equal to or greater than the value of Td (U), and the difference between the two is more preferably 10 mN / m or more when the coating solution temperature is 40 ° C.

  In the present invention, the surface tension of the coating solution can be adjusted by adding various surfactants, for example, a fluorine-based surfactant.

  In general, the surface tension of the coating liquid requires a certain period of time from when a new surface is formed until it reaches parallel. In coating, when applied to a coating liquid on a substrate, for example, when the specific surface area is expanded, the orientation speed of the surfactant contained in the coating liquid on the coating surface, the type of surfactant The surface tension changes with the passage of time due to the difference in surface orientation strength, evaporation of the solvent, etc., and such a non-equilibrium state is defined as dynamic surface tension.

  As a method for measuring the dynamic surface tension in the present invention, it can be measured by a known method. For example, a meniscus method, a dropping method, a γ / A curve method, a vibration jet method, a maximum bubble pressure method, a curtain coater method ( Journal of Fluid Mechanism J. Fluid Mech. (1981), vol.112.p443-458) can be obtained by appropriately selecting these methods. Among the standing waves of Sinous mode and Variose mode, which are formed when a rod is gently inserted into the membrane so that the two free interfaces between the front and back surfaces of the membrane do not touch each other, a specific point of the former Can be calculated by actually measuring the accuracy α of the tangent to the vertical direction.

  In addition, methods for measuring static surface tension are described in general interface chemistry and colloid chemistry reference books. For example, New Experimental Chemistry Course Vol. 18 (Interface and Colloid), The Chemical Society of Japan Issued by Maruzen Co., Ltd. 68-117 can be referred to, and specifically, it can be determined by using a ring method (Dunoi method) or a vertical plate method (Wilhelmy method).

  In the method for producing a thermal transfer image-receiving sheet of the present invention, a coating film cooling and setting step (hereinafter, also referred to as a cooling setting step or a setting step) in which the coating film is cooled and set before the drying is started after the coating step is completed. It is preferable in terms of forming a uniform and homogeneous coating film. Here, the cooling set step is, for example, promoting gelation by increasing the viscosity of the coating composition by slowing the temperature by applying cold air or the like to the coating film and slowing the material fluidity in each layer and each layer. This process. The temperature condition when using cold air is preferably 25 ° C. or lower, and more preferably 10 ° C. or lower. The time for which the coating film is exposed to the cold air depends on the coating conveyance speed, but is preferably 10 seconds or more and 120 seconds or less. As a means for improving the setting property of the coating solution, a method of adding various gelling agents such as gelatin, pectin, agar, carrageenan, gellan gum, etc. in addition to increasing the binder mass ratio in the coating solution is preferably used.

  In the method for producing a thermal transfer image-receiving sheet of the present invention, it is preferable to go through an aging step of heating for a certain time after the coating / setting / drying step from the viewpoint of further improving interlayer adhesion. Here, the aging step refers to, for example, treating the dried thermal transfer image-receiving sheet for a certain period of time under a certain temperature / constant humidity condition in order to make the chemical reaction in the coating film uniform such as a crosslinking reaction. Here, the period from the end of drying to the start of aging is preferably within 2 weeks, and more preferably within 1 week. As aging treatment conditions, the temperature is 30 ° C. to 80 ° C., the relative humidity is 20% to 80%, and the time depends on the temperature / humidity, but it is preferably 1 h to 240 h.

  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>
(Base material sheet)
In the present invention, as the base sheet used for the thermal transfer ink sheet, conventionally known materials can be used as the base sheet for the thermal transfer ink sheet. Specific examples of preferred substrate sheets 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)
In the present invention, 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 pigments used in the ink layer according to the present invention may be used alone or in combination of two or more.

  Below, the pigment | dye which can be used by this invention is demonstrated.

  The dye-containing region used in the thermal transfer ink sheet of the present invention can be two or more dye-containing regions that differ in hue. For example, the dye-containing region includes a yellow dye-containing region, a magenta dye-containing region, and a cyan dye-containing region. An embodiment in which a dye-containing region is formed after the dye-containing region, and the dye-containing region is formed of an ink layer containing a black dye, and the dye-free region is next to the region. The formed mode and the dye-containing area are composed of an area containing a yellow dye, an area containing a magenta dye, an area containing a cyan dye, and an area containing a black dye. The aspect etc. in which the containing area | region was formed 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 above 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, and an i-propyl group. Examples of a 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 group (for example, 2-tetrahydrofuryl group, 2-thiophenyl group, 4-imidazolyl group, 2-pyridyl group, etc.) Halogen 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 And the like, carbamoyl groups (for example, dimethylcarbamoyl group, alkylcarbamoyl groups 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 benzo, Aryloxy groups such as yloxy groups and pentafluorobenzoyloxy groups), urethane groups (for example, alkylurethane groups such as N, N-dimethylurethane groups, N-phenylurethane groups, N- (pcyanophenyl) urethane groups, etc. Aryl urethane groups, etc.), sulfonyloxy groups (eg, alkylsulfonyloxy groups such as methanesulfonyloxy group, trifluoromethanesulfonyloxy group, n-dodecanesulfonyloxy group, aryl such as benzenesulfonyloxy group, ptoluenesulfonyloxy group) Sulfonyloxy group, etc.), amino group (for example, dimethylamino group, cyclohexylamino group, alkylamino group such as n-dodecylamino group, anilino group, arylamino group such as pt-octylanilino group, etc.), sulfonyl Amino groups (eg Methanesulfonylamino group, heptafluoropropanesulfonylamino group, alkylsulfonylamino group such as n-hexadecylsulfonylamino group, p-toluenesulfonylamino group, arylsulfonylamino group such as pentafluorobenzenesulfonylamino, etc.), sulfamoyl An amino group (for example, an alkylsulfamoylamino group such as N, N-dimethylsulfamoylamino group, an arylsulfamoylamino group such as N-phenylsulfamoylamino group), an acylamino group (for example, acetylamino) Group, alkylcarbonylamino group such as myristoylamino group, arylcarbonylamino group such as benzoylamino group), ureido group (for example, alkylureido group such as N, N-dimethylaminoureido group, N-phenylureido group) 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 group (for example, dimethylsulfamoyl group, alkylsulfamoyl group such as 4- (2,4-di-t-amylphenoxy) butylaminosulfonyl group, arylsulfamoyl group such as phenylsulfamoyl group, etc. ), Alkylthio group (for example, methylthio group, t-octylthio group, etc.), arylthio group (for example, phenylthio group, etc.), heterocyclic thio group (for example, 1-phenyltetrazole-5-thio group, 5-methyl1,3 , 4-oxadiazole-2-thio group, etc.).

  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 examples of a preferable 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 examples of a preferable 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 of 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, and 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 -Nitrophenyl, 3-acylaminophenyl, 2-methoxyphenyl, etc. groups), cyano group Alkoxyl 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 a condensed ring 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 above 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 according to the present invention contains a binder resin together with the dye.

  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 according to the present invention may 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 ink layer according to the present invention may have a thickness of about 0.1 to 3.0 μm, preferably about 0.3 to 1.5 μm.

(Protective layer)
The thermal transfer ink sheet according to the present invention 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.

  Examples of the epoxy-modified resin used in the present invention 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, epoxy modified polystyrene, epoxy modified polymethyl methacrylate, epoxy modified silicone, copolymer of epoxy modified polystyrene and epoxy modified polymethyl methacrylate, copolymer of epoxy modified acrylic and epoxy modified polystyrene, epoxy modified acrylic and epoxy modified Examples include silicone copolymers, preferably epoxy-modified acrylic, epoxy-modified polystyrene, and epoxy-modified polymers. Methacrylate, epoxy-modified silicone, more preferably a copolymer of epoxy-modified polystyrene and epoxy-modified polymethylmethacrylate, a copolymer of epoxy-modified acrylic and epoxy-modified polystyrene, and a copolymer of epoxy-modified acrylic and epoxy-modified silicone. is there.

<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 thermal transferable protective layer of the present invention 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, In addition, for the purpose of increasing the adhesive force between the non-transferable release layer and the heat transferable protective layer before application of heat to that after application of heat, (1) together with the resin binder, average particles 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) it preferably contains 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. End up.

  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, A resin or fine particles may be further added. In that case, the release layer preferably 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. I can do it. 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 over time due to the influence of the environment over a long period of time.

  Examples of ultraviolet absorbers include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers. Specific examples include Tinuvin P, Tinuvin 234, Tinuvin 320, Tinuvin 326, Tinuvin 327, and Tinuvin 328. Tinuvin 312, Tinuvin 315 (Ciba Geigy), Sumisorb-110, Sumisorb 130, Sumsorb-140, Sumisorb-200, Sumisorb-250, Sumsorb-300, Sumisorb-320, Sumisorb-340, Sumisorb-340, Sumisorb-340, Sumisorb-340 400 (above, manufactured by Sumitomo Chemical Co., Ltd.), Mark LA-32, Mark They can be obtained from the market under trade names such as LA-36 and Mark 1413 (manufactured by Adeka Argus Chemical Co., Ltd.), and any of them can be used in the present invention.

  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 in the present invention. .

  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-mentioned 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 ultraviolet 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, and oxidizing action. In addition to the inhibitor, a light stabilizer that has been conventionally known as an additive of a synthetic resin 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 of the present invention, it is preferable to provide a heat-resistant slipping layer on the surface opposite to the ink layer across the base sheet.

  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, and nitrocellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, and 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 resins 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 give heat-resistant slip. Examples of release agents or lubricants 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, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<< Preparation of thermal transfer image-receiving sheet >>
[Preparation of Thermal Transfer Image Receiving Sheet 1: Comparative Example]
On one surface of the foamed film (Toyobo Co., Ltd., Pyrene Film P4256, thickness 60 μm), the intermediate layer coating solution 1 and the image receiving layer coating solution 1 having the following composition were each 0.2 g / in solid content. m ^2, so that 5.0 g / ^{m 2} (after drying), was applied by a gravure printing machine.

(Intermediate layer coating solution 1)
Urethane resin (DP urethane: manufactured by Showa Ink Industries Co., Ltd.) 60 parts by mass Curing agent (Coronate 2030: manufactured by Nippon Polyurethane Industry Co., Ltd.) 1 part by mass Methyl ethyl ketone / toluene = 1/1 20 parts by mass (Coating liquid 1 for image receiving layer)
Vinyl chloride-vinyl acetate copolymer (Denka vinyl # 1000A: manufactured by Denki Kagaku Kogyo Co., Ltd.)
60 parts by mass Polyester (Byron 600: manufactured by Toyobo Co., Ltd.) 40 parts by mass Amino-modified silicone (X-22-3050C: manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by mass Epoxy-modified silicone (X-22-3000E: manufactured by Shin-Etsu Chemical Co., Ltd.) ) 2 parts by mass Methyl ethyl ketone / toluene = 1/1 50 parts by mass Next, on one side of the coated paper (manufactured by Shin-Oji Paper, New Top 157 g / m ² ) The back layer was formed by applying with a gravure printing machine so that the solid content after drying was 5.0 g / m ² .

(Back surface layer coating solution 1)
Acrylic resin (BR-85: manufactured by Mitsubishi Rayon Co., Ltd.) 10 parts by mass Teflon (registered trademark) filler (Lublon L-5: manufactured by Daikin Industries, Ltd.) 0.1 parts by mass Methyl ethyl ketone / toluene = 1 / 19.5 parts by mass Next The adhesive layer coating solution 1 having the following composition is applied to the other surface of the coated paper by a gravure printing machine so that the solid content is 5.0 g / m ² (after drying), and dried to form an adhesive layer. Formed.

(Coating liquid 1 for adhesive layer)
Polyester-based pressure-sensitive adhesive (SK Dyne 5273: manufactured by Soken Chemical Co., Ltd.) 80 parts by mass Methyl ethyl ketone / toluene / ethyl acetate = 1/1/1 20 parts by mass Polyethylene filler (average particle size 5 μm) 80 parts by mass Adhesive for the above coated paper The coated surface and the side on which the image receiving layer of the foamed film was not formed were overlapped and adhered by dry lamination. The lamination conditions were a heating temperature of 60 ° C. and a pressurization time of 20 seconds. Thus, a thermal transfer image receiving sheet 1 was produced.

[Preparation of Thermal Transfer Image Receiving Sheet 2: Comparative Example]
On a polyolefin laminate paper (referred to as RC paper in Table 1), an aqueous heat insulating layer coating liquid 1 having the following composition is applied with a wire bar and dried, and then an aqueous image receiving layer having the following composition is formed with a wire bar. The coating liquid 2 was applied and dried to prepare a thermal transfer image receiving sheet 2. The heat-insulating layer was applied at a dry solid content of 25 g / m ² , and the image-receiving layer was applied at a coating amount of 4.0 g / m ² .

(Insulation layer coating solution 1)
Hollow particle microsphere MB927 (Honen's average particle size 7 μm) 50 parts by mass Urethane emulsion 45 parts by mass Methylcellulose 5 parts by mass (Image-receiving layer coating solution 2)
Polyester resin emulsion (Vaironal MD-1200: manufactured by Toyobo Co., Ltd.)
65 parts by mass Silica fine particles (Aerosil 200: manufactured by Nippon Aerosil Co., Ltd.) 25 parts by mass Long chain alkyl group-type release resin PR-18W (manufactured by Nippon Shokubai Co., Ltd.) 5 parts by mass Associative thickener (BORCHIGEL-L75: Hoechst Japan) 5 parts by mass [Production of thermal transfer image-receiving sheet 3: Comparative example]
The coating solution 2 for the heat insulation layer containing the following foamed particles was coated on a polyethylene terephthalate film (abbreviated as PET in Table 1, trade name: Lumirror S10; manufactured by Toray Industries, Inc.) using a wire bar and a dryer. After drying, a heat insulating layer having a thickness of 10 μm was formed.

(Insulation layer coating solution 2)
Expanded particles (Matsumoto Microsphere F-80GSE, particle diameter of about 20 to 30 μm, manufactured by Matsumoto Yushi Co., Ltd.) 10 parts by mass Kuraray Poval PVA203 (polyvinyl alcohol, polymerization degree 300, manufactured by Kuraray Co., Ltd.)
10 parts by mass of water 80 parts by mass Next, on the heat insulating layer formed above, the image receiving layer coating liquid 3 having the following composition was applied using a wire bar and dried at a drying temperature of 80 ° C. for 1 minute to form an image receiving layer. After forming, a release layer coating solution 1 having the following composition is applied using a wire bar, dried at a drying temperature of 80 ° C. for 1 minute to form a release layer, and then aged at 60 ° C. for 12 hours. Thus, a thermal transfer image receiving sheet 3 was produced.

(Image-receiving layer coating solution 3)
Polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd .: KS-1) 4.7 parts by mass Toluene 21.4 parts by mass Methyl ethyl ketone 64.3 parts by mass (Releasing layer coating solution 1)
Silicone resin (manufactured by Toray Silicone Co., Ltd .: SR2411) 16.65 parts by mass Acrylic silicon block copolymer (manufactured by NATCO: LDL500) 0.37 parts by mass 2-propanol 85.5 parts by mass [Production of thermal transfer image-receiving sheet 4: comparison 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 subbing layer of the porous layer surface 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 Is applied to the one surface by the wire bar coating method and dried at 120 ° C. for 1 minute, and the dry solid content is 3.5 g / m ^2. The heat insulation layer was formed. Next, an intermediate layer coating solution 2 having the following composition was applied by a wire bar coating method and dried at 120 ° C. for 1 minute to form an intermediate layer having a dry solid content of 2.0 g / m ² . Next, the following image-receiving layer coating solution 4 is applied by a wire bar coating method and dried at 120 ° C. for 1 minute to form an image-receiving layer having a dry solid content of 4.0 g / m ² to produce a thermal transfer image-receiving sheet 4. did.

(Insulation layer coating solution 3)
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
30 parts by mass Gas phase method silica (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd., primary particle size 12 nm)
20 mass parts Pure water 20 mass parts The viscosity of this heat insulation layer coating liquid 3 was 40 mPa * s at 40 degreeC.

(Intermediate layer coating solution 2)
8% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
15 parts by mass Acid-treated gelatin 15 parts by mass 6% nitric acid aqueous solution 6 parts by mass Anatase-type titanium oxide 10 parts by mass Pure water 54 parts by mass The viscosity of this intermediate layer coating solution 2 was 60 mPa · s at 40 ° C.

(Image-receiving layer coating solution 4)
Water-dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34% by mass)
50 parts by mass Acid-treated gelatin 8 parts by mass Fluorosurfactant (FC-4430, manufactured by Sumitomo 3M) 1.2 parts by mass Pure water 31.2 parts by mass The viscosity of this image-receiving layer coating solution 4 is 60 mPa · s.

[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 heat-insulating layer coating solution 4 having the following composition was used instead of the heat-insulating layer coating solution 3.

(Insulation layer coating solution 4)
Hollow particles (Nippon ZEON Co., Ltd .: Nipol MH5055, average particle size 0.5 μm, hollow ratio 55%) 31.2 parts by mass 8% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235)
31.2 parts by mass Acid-treated gelatin 6.4 parts by mass Pure water 31.2 parts by mass The viscosity of the heat insulating layer coating solution 4 was 40 mPa · s at 40 ° C.

[Preparation of Thermal Transfer Image Receiving Sheet 6: Present Invention]
In the production of the thermal transfer image-receiving sheet 4, the heat-insulating layer coating solution 3, the intermediate layer coating solution 3 and the image-receiving layer coating solution 4 were immediately applied after three layers were simultaneously applied using a slide hopper type multilayer coating apparatus. A thermal transfer image-receiving sheet 6 was produced in the same manner except that drying with warm air was performed.

[Preparation of Thermal Transfer Image Receiving Sheet 7: Present Invention]
In the production of the thermal transfer image-receiving sheet 6, the thermal transfer image-receiving sheet was prepared in the same manner except that the three-layer simultaneous multilayer coating was applied, followed by a setting process for 1 minute with cold air at 5 ° C. and then drying with warm air. 7 was produced.

[Preparation of Thermal Transfer Image Receiving Sheet 8: Present Invention]
In the production of the thermal transfer image receiving sheet 7, a thermal transfer image receiving sheet 8 was produced in the same manner except that an aging treatment was performed at 45 ° C. for 24 hours one day after drying.

[Preparation of Thermal Transfer Image Receiving Sheet 9: Present Invention]
A thermal transfer image receiving sheet 9 was prepared in the same manner as the thermal transfer image receiving sheet 8 except that the image receiving layer coating solution 5 in which 3.5 parts by mass of NiCl ₂ was added as a metal source to the image receiving layer coating solution 4 was used.

[Preparation of Thermal Transfer Image Receiving Sheet 10: Present Invention]
In the preparation of the thermal transfer image-receiving sheet 9, the image-receiving layer coating solution 4 is changed to an image-receiving layer coating solution 6 having the following composition, and the release layer coating solution 2 having the following composition is further used on the image-receiving layer. A thermal transfer image receiving sheet 10 was prepared in the same manner except that a release layer was provided so as to be 0.5 g / m ² and four layers including the release layer coating solution 2 were simultaneously applied.

(Image-receiving layer coating solution 6)
Water-dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34% by mass)
50 parts by mass Acid-treated gelatin 8 parts by mass NiCl ₂ 3.5 parts by mass Pure water 40.8 parts by mass The viscosity of the image-receiving layer coating solution 6 was 60 mPa · s at 40 ° C.

(Release layer coating solution 2)
Water-dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34% by mass)
50 parts by weight Acid-treated gelatin 8 parts by weight Fluorosurfactant (FC-4430, manufactured by Sumitomo 3M) 1.2 parts by weight Pure water 40.8 parts by weight The viscosity of the release layer coating solution 2 is 60 mPa at 40 ° C.・ It was s.

[Preparation of Thermal Transfer Image Receiving Sheet 11: Present Invention]
In the production of the thermal transfer image-receiving sheet 10, a polyethylene terephthalate film (Table 1) having a thickness of 100 μm provided with an undercoat layer described in Example 1 of Japanese Patent Application Laid-Open No. 2003-72229 was used instead of polyethylene-coated paper. The thermal transfer image-receiving sheet 11 was prepared in the same manner except that it was changed to “abbreviated as PET”.

[Preparation of Thermal Transfer Image Receiving Sheet 12: Present Invention]
In the production of the thermal transfer image-receiving sheet 10, a thermal transfer image-receiving sheet 12 was produced in the same manner except that the heat-insulating layer coating liquid 4 used in the production of the thermal transfer image-receiving sheet 5 was used instead of the heat-insulating layer coating liquid 3.

[Preparation of Thermal Transfer Image Receiving Sheet 13: Reference Example ]
In the production of the thermal transfer image-receiving sheet 10, two layers are simultaneously applied by using the heat insulating layer coating solution 3 and the intermediate layer coating solution 2 using a slide hopper type multilayer coating apparatus, and then 5 in the setting step. It was treated with cold air at 1 ° C. for 1 minute and then dried with warm air. Subsequently, the image receiving layer coating solution 6 and the release layer coating solution 2 are used to perform two-layer simultaneous multilayer coating using a slide hopper type multilayer coating apparatus, and then in a setting process with 5 ° C. cold air for 1 minute. Treatment was followed by drying with warm air. Next, an aging treatment was performed at 45 ° C. for 24 hours one day after drying to prepare a thermal transfer image receiving sheet 13.

[Preparation of Thermal Transfer Image Receiving Sheet 14: Present Invention]
In the production of the thermal transfer image-receiving sheet 10, the amount of pure water of the heat insulating layer coating liquid 3 was reduced, and the heat insulating layer coating liquid 5 having a viscosity at 40 ° C. changed from 40 mPa · s to 70 mPa · s was used in the same manner. A thermal transfer image receiving sheet 11 was produced.

[Preparation of Thermal Transfer Image Receiving Sheet 15: Reference Example ]
In the production of the thermal transfer image-receiving sheet 13, the heat-insulating layer coating solution 3 and the image-receiving layer coating solution 6 obtained by adding a surfactant to the heat-insulating layer coating solution 3 and the image-receiving layer coating solution 6 under the conditions described below are used. A thermal transfer image receiving sheet 15 was prepared in the same manner except that the release layer coating solution 3 having the following composition was used instead of the mold layer coating solution 2.

(Addition of surfactant)
In the heat insulation layer coating solution 5, 0.3 part by mass of a fluorosurfactant was added to the heat insulation layer coating solution 3. In the image-receiving layer coating solution 7, 0.85 parts by mass of a fluorosurfactant was added to the image-receiving layer coating solution 6.

(Release layer coating solution 3)
Water-dispersible polyester (Toyobo Co., Ltd., MD-1200, solid content 34% by mass)
50 parts by weight Acid-treated gelatin 8 parts by weight Silicone emulsion (X-52-175 manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts by weight Pure water 40.8 parts by weight The viscosity of the release layer coating solution 3 is 60 mPa at 40 ° C.・ It was s.

(Surface tension balance between coating solutions)
As a result of measuring the static surface tension difference and the dynamic surface tension difference between the above coating solutions using a commercially available measuring machine, it was as follows.

<Static surface tension balance>
Intermediate layer coating solution 2-heat insulation layer coating solution 6 = 3 mN / m
Image-receiving layer coating solution 7-release layer coating solution 3 = 2 mN / m
<Dynamic surface tension balance>
Intermediate layer coating solution 2-heat insulation layer coating solution 6 = 9 mN / m
Image-receiving layer coating solution 7-release layer coating solution 3 = 6 mN / m
[Preparation of Thermal Transfer Image Receiving Sheet 16: Present Invention]
On the produced thermal transfer image receiving sheet 9, a release layer coating solution 4 having the following composition is applied and dried using a wire bar under the condition that the solid content is 0.5 g / m ^2, and the thermal transfer image receiving sheet 16 is applied. Was made.

(Release layer coating solution 4)
Vinyl chloride vinyl acetate copolymer (vinyl chloride acetic acid / vinyl acetate = 95/5)
10 parts by mass Epoxy-modified silicone (X-22-8300T manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass Methyl ethyl ketone / toluene = 1/1 40 parts by mass Representative of thermal transfer image receptor sheet 1 to thermal transfer image receptor sheet 16 produced as described above Table 1 summarizes the features of various structures and manufacturing methods.

<Image formation>
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 each thermal transfer image receiving sheet and the ink layer of the following thermal transfer ink sheet are set in an overlapping manner, and the applied energy is sequentially increased while being pressed by a thermal head and a platen roll, so that yellow, magenta, cyan, neutral Each step pattern patch (three colors of yellow, magenta, and cyan) is heated from the back side of the ink layer at a feed rate of 2.5 msec / line and a feed length per line of 85 μm. Images 1 to 16 were formed by transferring each dye on the image receiving layer.

Thermal transfer sheet A: a thermal transfer ink sheet for CAMEDIA P-400 manufactured by Olympus Corporation, used in combination with thermal transfer image receiving sheets 1-8
Thermal transfer sheet B: Thermal transfer ink sheet for Pe602 manufactured by Konica Minolta Photo Imaging Co., used in combination with thermal transfer image receiving sheets 9 to 16 << Evaluation of formed image >>
The images printed as described above were evaluated according to the following methods.

(Evaluation of curl characteristics)
Each of the produced thermal transfer image-receiving sheets was cut into a 20 cm × 20 cm square, allowed to stand on a flat plate with the image-receiving layer on top in an environment of 23 ° C. and 50% RH, and left for 5 hours. The maximum value of the height from the flat plate at the corner was measured and used as a measure of the curl characteristics.

(Evaluation of sensitivity)
In the above image forming method, each thermal transfer transfer sheet is used to form an image while changing the applied energy, and the applied energy E (mJ / mm ² ) required to obtain a reflection density of 1.0 is measured. The sensitivity was evaluated according to the standard.

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
(Evaluation of whiteout failure tolerance)
The printed step pattern patch images were visually observed for the occurrence of white spots (white spot failure in the solid image) and evaluated for white fault tolerance 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. , In practically acceptable range ×: A strong white spot failure has occurred in the image, which is a quality that is a practical problem (evaluation of interlayer adhesion)
Each thermal transfer image receiving sheet was subjected to a cross cut test in accordance with JIS K5400. On the surface of each thermal transfer image receiving sheet, eleven notches of 90 ° with respect to the surface were inserted in a vertical direction and a horizontal direction at intervals of 1 mm to make 100 1 mm square grids. A commercially available cellophane tape was affixed to this, and one end of the tape was peeled off vertically by hand, and the ratio of the peeled area of the thermal transfer image-receiving sheet constituting layer to the tape area affixed from the score line was evaluated according to the following rank. .

A: No peeling of the thermal transfer image-receiving sheet constituting layer was observed. O: The area ratio of the peeled thermal transfer image-receiving sheet constituting layer was less than 5%. Δ: The area ratio of the peeled thermal transfer image-receiving sheet constituting layer. It was 5% or more and less than 10%. X: The area ratio of the peeled thermal transfer image-receiving sheet constituting layer was 10% or more and less than 20%. XX: The area ratio of the peeled functional film was 20%. (Evaluation of image preservation)
After measuring the maximum density Dmax1 of the created neutral (yellow, magenta, and cyan three-color overlay) image, this image was stored in an environment of 50 ° C. and 80% RH for 170 hours, and similarly the maximum of the neutral image The density Dmax2 was measured, the image remaining rate was determined according to the following formula, and the image storage stability (humidity resistance) was evaluated according to the following criteria.

Image residual ratio (%) = (Dmax2 / Dmax1) × 100
◎: Image remaining rate is 97% or more ○: Image remaining rate is 90% or more and less than 97%
Δ: Image remaining ratio is 80% or more and less than 90%. X: Image remaining ratio is less than 80%.

  As is apparent from the results shown in Table 1, the thermal transfer image-receiving sheet having the constitution of the present invention has excellent curl characteristics and white-out failure resistance, and maintains high sensitivity with respect to the comparative example. It can be seen that the film is excellent in the property and image storage stability (humidity resistance).

Claims (14)

In a thermal transfer image-receiving sheet having a heat insulating layer as the lowest layer and an image receiving layer on a substrate , and having an intermediate layer between the heat insulating layer and the image receiving layer , the heat insulating layer contains inorganic fine particles or hollow particles. At least all the layers constituting the image receiving layer from the heat insulating layer are formed by an aqueous coating and simultaneous multilayer coating method, and the coating liquid for forming each layer has a viscosity of η _{1 as the} coating liquid viscosity for forming the lowermost layer. A thermal transfer image receiving sheet characterized by satisfying the condition of η ₂ > η ₁ when the coating solution viscosity of the constituent layers excluding the lower layer is η ₂ .   2. The thermal transfer image receiving sheet according to claim 1, wherein all the layers constituting the surface side having the image receiving layer of the base material are formed by an aqueous coating method and a simultaneous multilayer coating method. The thermal transfer image-receiving sheet according to claim 1 or 2, wherein η ₁ is 100 mPa · s or less and η ₂ is ₁₅ mPa · s or more and 500 mPa · s or less when the coating solution temperature is 40 ° C.   The thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein the image-receiving layer contains a metal ion-containing compound capable of reacting with a chelate-forming dye to form a chelate compound.   The thermal transfer image-receiving sheet according to any one of claims 1 to 4, wherein the image-receiving layer contains a release agent.   The thermal transfer image receiving sheet according to any one of claims 1 to 4, wherein a release layer is provided on the first image receiving layer.   A dye in which the image receiving layer is composed of two or more layers, the image receiving layer located farthest from the substrate contains a releasing agent, and any one of the other image receiving layers is capable of chelating. The thermal transfer image-receiving sheet according to any one of claims 1 to 3, further comprising a metal ion-containing compound capable of reacting with and forming a chelate compound.   The thermal transfer image receiving sheet according to any one of claims 1 to 7, wherein the substrate is a resin-coated paper having a thickness of 50 to 250 µm. In the method for producing a thermal transfer image-receiving sheet, which has a heat-insulating layer as the lowest layer and an image-receiving layer on a substrate, and an intermediate layer between the heat-insulating layer and the image-receiving layer , the heat-insulating layer contains inorganic fine particles or hollow particles All the layers including the particles and constituting at least the image receiving layer from the heat insulating layer are formed by water-based coating and simultaneous multilayer coating method, and the coating solution for forming each layer has a coating solution viscosity of η ₁ , when the viscosity of the coating solution of the constituent layers except the outermost lower and η _2, η _2> thermal transfer image-receiving sheet manufacturing method, wherein the eta ₁ condition is satisfied.   10. The method for producing a thermal transfer image receiving sheet according to claim 9, wherein all layers constituting the surface side having the image receiving layer of the base material are formed by an aqueous coating and a simultaneous multilayer coating method. 11. The method for producing a thermal transfer image receiving sheet according to claim 9, wherein η ₁ is 100 mPa · s or less and η ₂ is ₁₅ mPa · s or more and 500 mPa · s or less when the coating solution temperature is 40 ° C. 11.   The method for producing a thermal transfer image receiving sheet according to any one of claims 9 to 11, further comprising a coating film cooling and setting step between the coating step and the drying step.   An aging process is performed after a drying process is complete | finished, The manufacturing method of the thermal transfer image receiving sheet as described in any one of Claims 9-12 characterized by the above-mentioned. The method for producing a thermal transfer image-receiving sheet according to any one of claims 9 to 13, wherein the conditions defined by the following formulas (1) and (2) are simultaneously satisfied when at least two layers are applied simultaneously. .
Formula (1)
Ts (L) ≧ Ts (U)
Formula (2)
Td (L) ≧ Td (U)
Where
Ts (L): Static surface tension of the coating solution constituting the relatively lower layer in the simultaneous application Ts (U): The coating solution constituting the relatively upper layer in the simultaneous application Static surface tension Td (L): Dynamic surface tension of a coating solution constituting a relatively lower layer in simultaneous application Td (U): Constructing a relatively upper layer in simultaneous application It represents the dynamic surface tension of the coating liquid.