JP5061947B2 - Thermal transfer image receiving sheet - Google Patents

Description

  The present invention relates to a thermal transfer image receiving sheet used for printing by a thermal transfer system.

As a method of forming an image using thermal transfer, a thermal transfer sheet (hereinafter referred to as “ink ribbon”) having a dye layer in which a thermal diffusion dye (sublimation dye) as a recording material is supported on a substrate sheet such as a plastic film. And a thermal diffusion transfer system (sublimation thermal transfer system) that forms a full-color image by superimposing a thermal transfer image-receiving sheet provided with a receiving layer on another substrate sheet such as paper or plastic film. ing. Since this method uses a thermal diffusion dye as a color material, the density and gradation can be freely adjusted in dot units, and a full-color image exactly as the original can be clearly displayed on the image-receiving sheet. It is applied to color image formation for computers and the like. The image is of a high quality comparable to a silver salt photograph.

  The receiving layer in the thermal transfer image-receiving sheet is formed by applying a receiving layer constituting resin using an organic solvent and an aqueous receiving layer formed by applying the receiving layer constituting resin using an aqueous solvent. Broadly divided into layers. In particular, the usefulness of the water-based receptive layer has attracted attention from the viewpoint of environment or safety.

  On the other hand, as a method for forming a thermal transfer image-receiving sheet, a method in which a porous layer and a receiving layer are sequentially applied and dried on a base sheet by gravure coating, etc. There are known wet-on-wet methods, simultaneous multilayer coating methods in which a plurality of layers are simultaneously coated on a substrate sheet, and the like. Among these forming methods, the simultaneous multi-layer coating method is attracting attention because it can obtain a thermal transfer image-receiving sheet with a smaller number of steps than other forming methods.

As an example of the simultaneous multilayer coating method, for example, in the example of Patent Document 1 (production of the thermal transfer image receiving sheet 5), a plurality of layers such as a heat insulating layer and an image receiving layer are formed on the substrate by simultaneous multilayer coating. A thermal transfer image receiving sheet is disclosed. Specifically, it is described that a thermal transfer image receiving sheet is obtained by using a slide coating method as a simultaneous multi-layer coating method. Patent Document 2 discloses a method for producing a thermal transfer image-receiving sheet, characterized in that an aqueous intermediate layer and an aqueous receiving layer are applied simultaneously (for example, Patent Document 2 Claim 1). Discloses an ink jet recording medium having a water-soluble resin as the outermost layer (for example, Patent Document 3 claim 1), which describes simultaneous application of an ink-receiving layer coating solution and a basic solution.

In particular, since the thermal transfer image-receiving sheet provided with the above-described aqueous receiving layer is suitable to be formed by the above-described simultaneous multilayer coating method, the thermal transfer image-receiving sheet provided with the aqueous receiving layer is also expected from this viewpoint.
JP 2006-88691 A JP-A-6-171240 JP 2006-103040 A

  However, the thermal transfer image-receiving sheet provided with the water-based receiving layer has the following problems. That is, when an image is thermally transferred to the aqueous receiving layer side using a thermal transfer image receiving sheet having an aqueous receiving layer, there is a problem that the image is blurred during storage after image formation. This blurring of the image during storage was prominent when stored in a high temperature and high humidity environment.

  In addition, when the degree of blurring of the image is significant, the dye dyed on the receiving layer may ooze out to the back surface of the base sheet, which may cause a problem in quality.

  The present invention has been made in view of the above problems, and is a case where an image is formed on the water-based receiving layer side of the thermal transfer image-receiving sheet, and then the image-formed sheet is stored in a high-temperature and high-humidity environment. Another object of the present invention is to provide a thermal transfer image receiving sheet capable of providing a sheet on which a high quality image is printed without blurring the image.

According to the diligent study by the present inventors, the problem of blurring of the image is due to the fact that the dye dyed on the receiving layer at the time of printing diffuses over time and shifts from the receiving layer to the base sheet side. As a result, it was found that the concentration of the dye in the receiving layer was lowered and the image was blurred. In addition, it has been found that the diffusion of the dye is remarkable and the blur of the image becomes remarkable when the dye diffuses to the base sheet side.

The present inventors have found that it is possible to prevent the diffusion of the dye inside the thermal transfer image-receiving sheet by providing a barrier layer made of a resin having a low dye-dyeing property at a position directly or indirectly adjacent to the receiving layer. The headline and the present invention were completed.

That is, the present invention
(1) In a thermal transfer image receiving sheet comprising a base sheet and at least a barrier layer and a receiving layer on the base sheet, the receiving layer is made of a dye-dyeable resin that can be dispersed or dissolved in an aqueous solvent. The barrier layer is a styrene α-methylstyrene acrylate resin having a glass transition point of 40 ° C. or higher that can be dispersed or dissolved in an aqueous solvent, and the color difference ΔEab before and after storage shown in the dye dyeing property test below. A thermal transfer image-receiving sheet, wherein the thermal transfer image-receiving sheet is made of less than 3 resin,
Dye dyeability test: 90 parts by weight of evaluation resin, 10 parts by weight of gelatin, and 10 parts by weight of silicone release agent were diluted with pure water and applied so that the solid content concentration of the evaluation resin was 30% by weight of the solution. A working solution is prepared, and a test piece is prepared by applying the coating solution on a 75 μm thick polyethylene terephthalate base film so that the coating film after drying is 4 g / m ^2, and then at 50 ° C. The test piece is placed in a heated oven and heated for 2 minutes, and then removed from the oven. After the test piece returns to room temperature, the a * value and b * value (L * a * b * Color Hue and Saturation Scale in the color system) measured with a colorimeter under the conditions of light source D65, illumination viewing angle 2 degrees, density calculation ISO Status A, no filter, and then the coating side Ink ribs having a dye layer containing cyan dye The superposed, by applying a pressure of 10 kg / cm ² by the blocking tester, temperature 40 ° C., then stored for 24 hours in an oven at 90% RH, then, out of the oven, at atmospheric pressure at room temperature, allowed to stand for 5 hours After that, the ink ribbon was manually pulled away from the test piece, and then the a * value and b * value of the coating film surface were measured in the same manner as described above, and the color difference ΔEa * before and after storage of the coating film according to the following (Equation 1). b * is calculated and the dyeing property of the evaluation resin is measured.
(Equation 1) ΔEa * b * = {(a * value after storage−a * value before storage) ² + (b * value after storage−b * value before storage) ² } ^1/2
(2) The thermal transfer image-receiving sheet as described in (1) above, wherein a resin neutralized with a volatile base is used as the resin that can be dispersed or dissolved in the aqueous solvent constituting the barrier layer.
(3) The thermal transfer image receiving sheet as described in (1) or (2) above, wherein the barrier layer is provided at a position in direct contact with the receiving layer,
(4) A porous layer, the barrier layer, and the receiving layer are laminated in this order on the substrate sheet, and the porous layer is made of a hollow particle resin that can be dispersed or dissolved in an aqueous solvent. The thermal transfer image receiving sheet according to any one of (1) to (3) above,
(5) The above-mentioned (1) to (4), wherein a cooling gelling agent is contained in all of the receiving layer and the barrier layer laminated on the base sheet or the porous layer. ) The thermal transfer image-receiving sheet according to any one of
(6) The thermal transfer image receiving sheet as described in any one of (1) to (5) above, wherein the barrier layer contains gelatin.
Is a summary.

  Since the thermal transfer image-receiving sheet of the present invention is provided with a barrier layer, when the image is formed on the receiving layer and then stored for a long time in a high-temperature and high-humidity environment, the image is not blurred or The degree of blur is very small, and it is possible to provide a high-quality image even after storage.

The effect of the present invention is that the dye dyed on the receiving layer diffuses in a high temperature and high humidity storage environment and attempts to migrate to another layer because the barrier layer has a low dye dyeing property. By the diffusion of the dye remaining before the layer. Therefore, in particular, in the thermal transfer image-receiving sheet of the present invention formed so that the receiving layer and the barrier layer are in direct contact with each other, the dye transfer from the receiving layer to the barrier layer is prevented, so that it was stored for a long time at high temperature and high humidity. Even in this case, the dye remains in the receiving layer and a clearer image can be maintained.

[Thermal transfer image receiving sheet]
Hereinafter, the best mode for carrying out the thermal transfer image-receiving sheet of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of the thermal transfer image receiving sheet of the present invention. A thermal transfer image receiving sheet 11 of the present invention shown in FIG. 1 is configured by laminating a barrier layer 3 and a receiving layer 2 in this order on a base sheet 1.

<Receptive layer>
First, the receiving layer 2 in the thermal transfer image receiving sheet 11 of the present invention will be described. The receiving layer 2 is a layer formed on the substrate sheet 1 and has a function of receiving a dye when a printed material is formed by the thermal transfer method using the thermal transfer image receiving sheet 11. The receiving layer 2 is mainly composed of a dye dyeable resin that can be dispersed or dissolved in an aqueous solvent. Further, it is desirable that the receiving layer 2 contains a release agent so that the dye layer can be smoothly peeled off after the pressure-bonding between the receiving layer and the dye layer at the time of printing.

Here, since the receiving layer 2 is a so-called aqueous receiving layer composed of a resin that can be dispersed or dissolved in an aqueous solvent, an additional layer is provided between the base sheet 1 and the receiving layer 2 like the thermal transfer image receiving sheet 11. Is formed, it is possible to simultaneously apply a plurality of layers including the receiving layer 2 on the base sheet 1. As described above, when the thermal transfer image-receiving sheet of the present invention is applied by the simultaneous multilayer coating method, it is desirable that the receiving layer 2 contains a cooling gelling agent.
The constituent materials that can be contained in the receiving layer are described in detail below.

(Dye dyeing resin)
The resin for constituting the receiving layer 2 in the present invention is not particularly limited as long as it is a resin that can be dispersed or dissolved in an aqueous solvent and has a dye dyeing property.

However, in order to further improve the heat resistance of the receiving layer 2, the receiving layer constituting resin preferably has a glass transition temperature of 20 ° C or higher, more preferably 30 ° C or higher, and 40 ° C or higher. Some are more preferred. Further, the receiving layer constituting resin preferably has a glass transition temperature of 120 ° C. or lower. This is because by using the receiving layer constituting resin having a glass transition temperature in such a range, it is possible to obtain the thermal transfer image receiving sheet 11 having particularly excellent heat resistance.

Examples of the receiving layer constituting resin include, for example, polyolefin resin, polyvinyl resin, polyester resin, polyurethane resin, polycarbonate resin, polyamide resin, poly (meth) acrylic acid resin, cellulose derivative resin, or polyether. System resin is used. In the present invention, any of these resins can be suitably used, and among them, a polyvinyl resin is preferably used.

  Examples of the polyvinyl resin suitably used as the receiving layer constituting resin in the present invention include, for example, vinyl chloride / vinyl acetate copolymer, vinyl chloride / acrylic compound copolymer, ethylene / vinyl chloride / acrylic acid ester copolymer, Examples thereof include an ethylene / vinyl acetate / vinyl chloride copolymer.

The vinyl chloride / vinyl acetate copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and vinyl acetate, and can be copolymerized with these essential monomers in addition to vinyl chloride and vinyl acetate. The body may be obtained by polymerizing a small amount.

The vinyl chloride / acrylic compound copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and an acrylic compound, and a single amount copolymerizable with these essential monomers in addition to vinyl chloride and an acrylic compound. The body may be obtained by copolymerization in a small amount.

Examples of the acrylic compound include acrylic acid; acrylic acid salts such as calcium acrylate, zinc acrylate, magnesium acrylate, and aluminum acrylate; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxy. Acrylic esters such as ethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate , Cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylo trimethacrylate It can be mentioned methacrylic acid esters such as propane.
In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.

  The ethylene / vinyl chloride / acrylic acid ester copolymer and the ethylene / vinyl acetate / vinyl chloride copolymer (hereinafter, these copolymers are collectively referred to as “ethylene / vinyl chloride copolymer”). Is not particularly limited as long as it is a copolymer obtained by polymerizing at least three monomers of ethylene, vinyl chloride and acrylate, or three monomers of ethylene, vinyl acetate and vinyl chloride. In addition to these three types of monomers, a small amount of a small amount of monomer may be copolymerized.

  The ethylene / vinyl acetate / vinyl chloride copolymer may be a copolymer of ethylene / vinyl acetate copolymer (EVA) and vinyl chloride. As the EVA / vinyl chloride copolymer, EVA may be used. It may be a graft copolymerized vinyl chloride. EVA includes those in which all or part of vinyl acetate units in the copolymer is saponified.

In the present invention, “acrylic acid ester” constituting the ethylene / vinyl chloride / acrylic acid ester copolymer is a concept including a methacrylic acid ester in addition to the acrylic acid ester. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, and trimethylolpropane triacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, dimethacrylic acid-1, Examples include 3-butylene and trimethylolpropane trimethacrylate.
In the present invention, only one type of the above-mentioned receptor layer constituting resin may be used, or two or more types having different monomer compositions, number average molecular weights, and the like may be used.

(Aqueous solvent)
In the present invention, the “aqueous solvent” used to disperse or dissolve the dye-dyeing resin constituting the receptor layer 2 refers to a solvent containing water as a main component. The proportion of water in the aqueous solvent is usually 60% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more. Examples of solvents other than water include 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; ketones such as acetone and methyl ethyl ketone. Amides such as N, N-dimethylformamide can be exemplified.

(Release agent)
In the receptor layer 2 in the present invention, the release agent is not an essential component, but is preferably used as a receptor layer constituent material for the following reasons. That is, as the dye dyeable resin for constituting the receiving layer 2 in the present invention, those having a glass transition temperature of 20 ° C. or higher and 120 ° C. or lower are preferably used as described above. Here, when the glass transition temperature of the dyeing property is relatively high, the releasability from the dye layer at the time of printing may be poor. The tendency of releasability is particularly remarkable when the glass transition temperature of the dye-dyeable resin is in the range of 40 ° C. or higher and 120 ° C. or lower. On the other hand, when a release agent is used as the receiving layer constituting material, it is possible to improve the releasability at the time of insufficient printing.

The release agent is preferably added so as to be in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the dye-dyeable resin.

Examples of the release agent used in the present invention include conventionally known ones such as silicone oil, phosphate ester compounds, and fluorine compounds. Among these, silicone oil is particularly suitable because it has good compatibility with the dye-dyeable resin used in the present invention. More specific examples of silicone oil include epoxy-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, phenyl-modified silicone oil, polyether-modified silicone oil, vinyl-modified silicone oil, and hydrogen-modified silicone oil. Modified silicone oil such as silicone oil is preferred. Also, emulsified silicone can be used.

(Cooling gelling agent)
Further, according to the present invention, a cooling gelling agent can be optionally added to the receiving layer 2. In particular, when producing a thermal transfer image receiving sheet in which a plurality of layers including a receiving layer are formed on a substrate sheet, such as the thermal transfer image receiving sheet 11, by a simultaneous multilayer coating method such as a slide coating method, the receiving layer is cooled. By adding a gelling agent, it becomes possible to manufacture with high efficiency. The inclusion of the cooling gelling agent in the receiving layer 2 makes it possible to produce the thermal transfer image receiving sheet 11 by simultaneously applying and laminating the receiving layer 2 and the barrier layer 3 in the simultaneous multilayer coating method. To.

  In each layer provided in the thermal transfer image-receiving sheet of the present invention such as a barrier layer, a porous layer, or an undercoat layer, which will be described later, addition of a cooling gelling agent is optional. When producing a thermal transfer image-receiving sheet, it is desirable that a cooling gelling agent is added to any layer.

The cooling gelling agent used in the present invention described above has a property of gelling when cooled. The cooling gelling agent is not particularly limited as long as it has cooling gelling properties. In particular, in the cooling gelling agent dissolved in water, the cooling gelling agent at 80 ° C. The viscosity of the cooling gelling agent at 15 ° C. is preferably 3 times or more, more preferably 5 times or more, and particularly preferably 10 times or more of the viscosity.

  Examples of the cooling gelling agent used in the present invention include gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, pectin and the like.

  The gelatin is composed of a peptide chain obtained by denaturing collagen having a triple helix structure. The gelatin partially recovers the triple helix structure by cooling, and the recovered triple helix structure. As a starting point, a three-dimensional network is formed to show cooling gelation characteristics.

  The above-mentioned κ-carrageenan, λ-carrageenan, and ι-carrageenan are natural polymer compounds mainly composed of galactose and 3,6-anhydrogalactose having a number average molecular weight of about 100,000 to 500,000 extracted from red algae seaweed. is there. It is characterized by having a half-ester type sulfate group in the molecule, and usually exhibits a gelling property by using a thickener such as locust bean gum or a metal salt compound in combination. is there.

  The pectin is a natural polysaccharide that constitutes a cell wall of a plant, and exhibits cooling gelation characteristics when used in combination with an ionic compound.

  In the present invention, any of the above cooling gelling agents can be suitably used. In the present invention, only one type of cooling gelling agent may be used, or two or more types of cooling gelling agents may be used in combination.

  Further, in the receiving layer forming coating solution for forming the receiving layer 2 of the present invention, the content of the cooling gelling agent gives the following effects sufficiently as long as the dye dyeing property of the receiving layer 2 is not disturbed. There is no particular limitation as long as it is within the range. That is, when the thermal transfer image-receiving sheet 11 is produced within a range not disturbing the dyeing property of the receiving layer 2, when the barrier layer 3 and the receiving layer 2 are simultaneously coated on the base sheet 1, the receiving layer A cooling gelling agent is added to such an extent that good applicability of the forming coating liquid is ensured and drying unevenness is prevented in the drying step. In general, the cooling gelling agent is preferably in the range of 2 to 50 parts by weight in terms of weight at the time of drying with respect to 100 parts by weight of the solid content in the coating liquid for forming the receiving layer, In particular, it is preferably in the range of 2 to 30 parts by weight, and more preferably in the range of 2 to 20 parts by weight. When the blending ratio of the cooling gelling agent is less than 2 parts by weight, for example, unevenness is likely to occur when the receiving layer forming coating solution is applied and dried on the base sheet 1, and simultaneous multilayer coating As a result, the thermal transfer image receiving sheet 11 may not be formed satisfactorily. On the other hand, when the amount is larger than the above range, for example, dyeing may be hindered during image formation, and the image density may decrease. The cooling gelling agent is generally dissolved in an aqueous solvent and then mixed with the receiving layer forming coating solution. The concentration at which the gelling agent is dissolved in the aqueous solvent is appropriately adjusted depending on the concentration and viscosity of the receiving layer coating solution or the viscosity and surface tension of other layers formed adjacent to the receiving layer 2. be able to.

(Optional additive)
In addition to the constituent material of the receiving layer 2 described above, other additives can be appropriately used as the constituent material of the receiving layer 2 without departing from the spirit of the present invention. Examples of other optional components include an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a pigment, an antistatic agent, a plasticizer, and a hot-melt material.

  The thickness of the receiving layer 2 configured as described above can be appropriately determined within a range in which a desired printing density can be expressed according to the type of the receiving layer constituting resin, the type of ink to be dyed, and the like. In particular, in the present invention, it is preferably in the range of 0.5 μm to 20 μm, particularly preferably in the range of 1 μm to 20 μm, and more preferably in the range of 1 μm to 15 μm.

  Each component of the constituent material of the receiving layer 2 described above is dispersed or dissolved in the aqueous solvent to adjust the receiving layer forming coating solution. The order in which each component is dispersed or dissolved in the aqueous solvent is not particularly limited, but when a cooling gelling agent is used, an appropriate amount of the cooling gelling agent is first dissolved in the aqueous solvent and then the other components. In general, the dissolved cooling gelling agent is mixed with an aqueous solvent in which other components are dispersed or dissolved.

  In particular, when the thermal transfer image-receiving sheet 11 is produced by the simultaneous multilayer coating method, the viscosity of the receiving layer forming coating liquid is such that it does not mix with other coating liquids that are simultaneously coated on the base sheet. If it is, it is not particularly limited, but at 40 ° C., preferably within the range of 1 mPa · s to 50 mPa · s, particularly preferably within the range of 5 mPa · s to 50 mPa · s, It is preferably within the range of 7 mPa · s to 40 mPa · s. The viscosity can be measured using, for example, a small vibration viscometer (VIBRO VISCOMETER CJV5000, manufactured by A & D).

Further, the solid content concentration of the coating solution for forming the receiving layer used for the production of the thermal transfer image-receiving sheet 11 by the simultaneous multilayer coating method is not particularly limited as long as the viscosity is within the above desired range. In particular, it is preferably in the range of 10 wt% to 50 wt%, and more preferably in the range of 10 wt% to 40 wt%. Each solid content is adjusted by the above-mentioned aqueous solvent so as to have such a solid content. It is preferably dispersed or dissolved. If the solid content concentration is too low, the viscosity of the solution decreases and the drying time becomes longer. If the solid content concentration is too high, the storage stability of the coating solution decreases, and the viscosity increases, which is inconvenient for coating. It is because it produces.

<Base material sheet>
Next, the base material sheet 1 used for the thermal transfer image-receiving sheet 11 of the present invention will be described. The base sheet 1 has a function of supporting the receiving layer 2 described above.
Hereinafter, the base sheet 1 will be described in detail.

  As the base material sheet 1 used in the present invention, as long as it has a desired heat resistance depending on the printing temperature or the like when an image is formed on the receiving layer 2 side using the thermal transfer image receiving sheet 11 of the present invention. It is not particularly limited. Specific examples include resin-coated paper, resin film base, and paper base, among which resin-coated paper is preferable.

  The resin-coated paper is usually formed by laminating a base resin layer on both sides of a base paper. Examples of the base paper constituting the base paper include natural pulp, synthetic pulp, and pulp paper made from a mixture thereof. Among these, it is preferable to use paper mainly composed of wood pulp. The base paper may be subjected to a conventionally known process such as a calendar process to be described later if necessary.

  The base paper can be produced by a known method, but a base paper that is calendered is preferable. This is because when a base paper that has been calendered is used for the base paper, the smoothness can be improved and the glossiness of the resulting thermal transfer image-receiving sheet can be enhanced. The thickness of the base paper is preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  The resin for forming the base resin layer is preferably a resin having a small neck-in and a good drawdown property. For example, polyolefin resin, polystyrene resin, vinyl resin, polyester resin, ionomer Resin, nylon, polyurethane and the like can be mentioned, and a polyolefin resin is preferable in that a film excellent in water resistance, strength, gloss and the like can be obtained.

  Examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, and polypentene. Among these, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and polypropylene are preferable, and polypropylene is particularly preferable. Is preferred.

  The base resin layer may be a film or sheet obtained by mixing one or more of the resins, and in addition to the resin for forming the base resin layer, a pigment, a filler, etc. It may be a film or sheet formed by adding Further, the resin for forming the base resin layer may be one obtained by blending an additive such as a modifier to improve adhesiveness. Examples of the modifier include olefin copolymers such as Tuffmer (manufactured by Mitsui Chemicals).

  As described above, the resin-coated paper obtained by laminating the base resin layer on both surfaces of the base paper can be produced by a known laminating method such as dry lamination, wet lamination, or extrusion. Each of the above layers can be subjected to a base treatment such as corona discharge treatment on the surface for the purpose of improving the interlayer adhesion. Moreover, the thickness of the base material sheet 1 which is the resin-coated paper as a whole is preferably in the range of, for example, 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  Next, the resin film substrate will be described. The resinous film substrate used as the substrate sheet 1 in the present invention is, for example, polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene. , Acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene-ethylene, From resins such as tetrafluoroethylene-hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride It is possible to form. In particular, in the present invention, polyethylene terephthalate or polypropylene resin can be suitably used as a resin for forming the resin film substrate.

As thickness of the base material sheet 1 which is the said resin-made film base materials, it is preferable to exist in the range of 20 micrometers-100 micrometers, for example, especially in the range of 25 micrometers-60 micrometers, and especially in the range of 30 micrometers-50 micrometers.

  Examples of the paper substrate used as the substrate sheet 1 include condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, Examples thereof include coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin-incorporated paper, paperboard, and cellulose fiber paper.

  In the case of using the paper base material as the base material sheet 1, the thickness is not particularly limited. For example, the thickness is in the range of 80 μm to 400 μm, particularly in the range of 100 μm to 300 μm, particularly in the range of 100 μm to 210 μm. It is preferable to be within the range.

<Barrier layer>
Next, the barrier layer 3 in the present invention will be described. The barrier layer 3 is formed between the base material sheet 1 and the receiving layer 2 described above, and has a function of improving the image storage stability of the thermal transfer image receiving sheet 11 of the present invention in a high temperature and high humidity environment. It is. In particular, it is desirable to provide the barrier layer 3 at a position in direct contact with the receiving layer 2 in order to effectively enjoy the image storage stability. However, it is not excluded to provide another layer between the receiving layer 2 and the barrier layer 3 without departing from the spirit of the present invention.

(Barrier layer 3 forming resin)
First, the barrier layer constituting resin used in the present invention will be described. The barrier layer constituting resin used in the present invention is a resin that can be dispersed or dissolved in an aqueous solvent and has a low dye dyeing property.

  In the present invention, the low dye dyeing property specifically means that the resin has a color difference ΔEab before and after storage shown in the following dye dyeing property test of less than 3. In the present invention, the dye dyeability test is carried out as follows.

First, 90 parts by weight of an evaluation resin (barrier layer constituting resin), 10 parts by weight of gelatin, and 10 parts by weight of a silicone release agent are diluted with pure water so that the solid content concentration of the evaluation resin is 30% by weight of the solution. The coating solution is prepared by applying the coating solution on a 75 μm thick polyethylene terephthalate base film so that the coating film after drying is 4 g / m ^2. Create a test specimen. Next, the test piece is placed in an oven heated to 50 ° C. and heated for 2 minutes. Then, the test piece is taken out of the oven, and the test piece returns to room temperature. Value and b * value (scale of hue and saturation in the L * a * b * color system) with a colorimeter, light source D65, illumination viewing angle 2 degrees, density calculation ISO Status A, no filter taking measurement. Next, an ink ribbon including a dye layer containing a cyan dye is overlapped on the coating film side, and a pressure of 10 kg / cm ² is applied by a blocking tester, and the oven is placed in an oven at a temperature of 40 ° C. and a humidity of 90% RH for 24 hours. After storage, after leaving the oven and leaving at atmospheric pressure for 5 hours at room temperature, the ink ribbon was manually pulled away from the test piece, and then the a * value and b * value of the coating surface were measured. The color difference ΔEa * b * before and after storage of the coating film is calculated according to the following (formula 1), and the dyeing property of the evaluation resin is measured.
In the present invention, Spectrolino manufactured by Gretag Macbeth was used as the colorimeter.

(Equation 1) ΔEa * b * = {(a * value after storage−a * value before storage) ² + (b * value after storage−b * value before storage) ² } ^1/2

As described above, when the dyeing property of the resin is tested by a test for forcibly dyeing the dye directly on the coating film itself by the dyeing property test, the color difference ΔEab before and after storage of the coating film composed of the resin If the resin is less than 3, it can be evaluated that the resin constituting the coating film has a very low dye dyeing property. Accordingly, when the barrier layer 3 is formed between the receiving layer 2 and the base sheet 1 with the resin having low dye dyeing property, the dye dyed on the receiving layer 2 is heated at high temperature and high humidity. Even if it is intended to diffuse in the storage environment and migrate to the barrier layer 3, it is difficult to dye the barrier layer 3, and as a result, before the barrier layer 3, that is, the receiving layer 2 The dye stays inside, and as a result, further diffusion of the dye can be prevented. From this viewpoint, the difference ΔEab between before and after the storage is more preferably less than 2.5, still more preferably less than 2, and particularly preferably less than 1.5.

  In the present invention, the resin having a color difference ΔEab of less than 3 described as a resin having a low dye dyeing property in the present invention has an extremely low compatibility with the dye, and the dye is almost dyed on the receiving layer in the dye dyeing property test. Therefore, the dye layer sticks to the surface of the receiving layer, and after storage, the ink ribbon cannot be smoothly peeled off from the coating film, and the a * value and b * value on the coating film surface after storage cannot be measured. Is also included.

The barrier layer-constituting resin used in the present invention preferably has a glass transition temperature of 20 ° C. or higher, more preferably 40 ° C. or higher, and even more preferably 50 ° C. or higher. This is because by using a barrier layer-constituting resin having a glass transition temperature in such a range, a thermal transfer image-receiving sheet particularly excellent in heat resistance can be obtained.

Examples of the barrier layer-constituting resin include polyolefin resins, polyvinyl resins, polyester resins, polyurethane resins, polycarbonate resins, polyamide resins, cellulose derivative resins, or polyether resins, and those having ΔEab of less than 3. Is used.

Examples of the polyvinyl resin suitably used as the barrier layer constituting resin in the present invention include, for example, vinyl chloride / vinyl acetate copolymer, vinyl chloride / acrylic compound copolymer, ethylene / vinyl chloride / acrylic ester copolymer, Examples thereof include an ethylene / vinyl acetate / vinyl chloride copolymer. In particular, an acrylic resin is preferable, and among them, a styrene α-methylstyrene acrylic acid resin, a methacrylic acid ester / acrylic acid copolymer, or a combination thereof is more preferable.

The vinyl chloride / vinyl acetate copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and vinyl acetate, and can be copolymerized with these essential monomers in addition to vinyl chloride and vinyl acetate. The body may be obtained by polymerizing a small amount.

The vinyl chloride / acrylic compound copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and an acrylic compound, and a single amount copolymerizable with these essential monomers in addition to vinyl chloride and an acrylic compound. The body may be obtained by copolymerization in a small amount.

Examples of the acrylic compound include acrylic acid; acrylic acid salts such as calcium acrylate, zinc acrylate, magnesium acrylate, and aluminum acrylate; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxy. Acrylic esters such as ethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate , Cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylo trimethacrylate It can be mentioned methacrylic acid esters such as propane.
In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.

  The ethylene / vinyl chloride / acrylic acid ester copolymer and the ethylene / vinyl acetate / vinyl chloride copolymer (hereinafter, these copolymers are collectively referred to as “ethylene / vinyl chloride copolymer”). Is not particularly limited as long as it is a copolymer obtained by polymerizing at least three monomers of ethylene, vinyl chloride and acrylate, or three monomers of ethylene, vinyl acetate and vinyl chloride. In addition to these three types of monomers, a small amount of a small amount of monomer may be copolymerized.

  The ethylene / vinyl acetate / vinyl chloride copolymer may be a copolymer of ethylene / vinyl acetate copolymer (EVA) and vinyl chloride. As the EVA / vinyl chloride copolymer, EVA may be used. It may be a graft copolymerized vinyl chloride. EVA includes those in which all or part of vinyl acetate units in the copolymer is saponified.

In the present invention, “acrylic acid ester” constituting the ethylene / vinyl chloride / acrylic acid ester copolymer is a concept including a methacrylic acid ester in addition to the acrylic acid ester. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, and trimethylolpropane triacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, dimethacrylic acid-1, Examples include 3-butylene and trimethylolpropane trimethacrylate.
In the present invention, only one kind of the barrier layer constituting resin may be used, or two or more kinds having different monomer compositions, number average molecular weights, and the like may be used.

  The styrene acrylic resin suitably used in the present invention is not particularly limited as long as it is a copolymer obtained by polymerizing two types of monomers, a styrene monomer and an acrylic monomer. In addition to the monomer, a small amount of a small amount of monomer may be copolymerized.

The styrene monomer is not particularly limited, and a known compound can be used. For example, alkylstyrene such as styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, α-hexylstyrene, 4-chlorostyrene, 3-chlorostyrene, There are halogenated styrenes such as 3-bromostyrene, 3-nitrostyrene, 4-methoxystyrene, vinyltoluene and the like.

On the other hand, the acrylic monomer is not particularly limited, and a known compound can be used. For example, acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; Acid; Methacrylic acid such as methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylolpropane trimethacrylate Examples include esters.
In the present specification, “acrylic” includes (meth) acrylic acid and / or an alkyl ester compound thereof.

In addition to the styrene monomer, acrylic acid monomer, and methacrylic acid monomer, the styrene acrylic resin may be copolymerized with known monomers that can be copolymerized with these monomers. Examples of such monomers include methyl acrylate, methyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, 1,3-dimethylbutyl Acrylic esters and methacrylic such as acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylbutyl methacrylate, pentyl methacrylate, heptyl methacrylate, nonyl methacrylate Acid esters; 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, dimethylaminoethyl acrylate, 2 Acrylic acid ester derivatives and methacrylic acid ester derivatives such as hydroxyethyl acrylate, 2-hydroxybutyl acrylate, ethyl-α- (hydroxymethyl) acrylate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; phenyl acrylate Acrylic acid aryl esters and acrylic acid aralkyl esters such as benzyl acrylate, phenylethyl acrylate, phenylethyl methacrylate; monoacrylic acid of polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, bisphenol A Esters or monomethacrylates; dimethyl maleate, malee Mention may be made of maleic acid dialkyl esters such as diethyl acid, vinyl acetate and the like. One or more of these monomers can be added as monomer components.

As described above, those having a ΔEab of less than 3 are selectively used as the barrier layer constituting resins listed above. In the present invention, only one kind of the barrier layer constituting resin may be used, or two or more kinds having different monomer compositions, number average molecular weights, and the like may be used.

  The “aqueous solvent” for dispersing or dissolving the barrier layer-constituting resin refers to a solvent containing water as a main component. In the above, the same as the aqueous solvent used for dispersing or dissolving the receiving layer-constituting resin. Things can be used. However, the aqueous solvent used in the receiving layer 2 and the aqueous solvent used in the barrier layer 3 may be the same, or different aqueous solvents may be selected.

As the resin that can be dispersed or dissolved in the aqueous solvent constituting the barrier layer 3, it is preferable to use a resin that is neutralized with a volatile base. That is, as a pre-process for dispersing or dissolving the barrier layer constituting resin in the aqueous solvent, the neutralizing agent may be used to neutralize the carboxyl group of the barrier layer constituting resin and then disperse or dissolve in the aqueous solvent. is there. At this time, various solutions are used as the neutralizing agent. However, when a sodium hydroxide solution or the like is used, the hydrophilic portion eventually remains in an ionic state as a sodium salt, and thermal transfer image receiving is performed. There is a risk of undesirable effects on the sheet. On the other hand, if a volatile neutralizing agent such as ammonia can be used, the barrier layer is volatilized in the process of drying the thermal transfer image-receiving sheet, so that it does not finally remain in the barrier layer. Therefore, it is preferable. More specifically, when an acrylic resin is used as the resin that is soluble in the aqueous solvent constituting the barrier layer 3, the carboxyl group derived from acrylic acid in the acrylic resin is volatile such as ammonia water. Neutralized with a solvent to form an ammonium salt or the like, and can be dispersed or dissolved in an aqueous solvent. And when manufacturing a thermal transfer image receiving sheet, a base part volatilizes in the drying process, and it is preferable since it does not remain in the barrier layer comprised from acrylic resin.

(Cooling gelling agent)
Next, the cooling gelling agent used for the barrier layer 3 will be described. A cooling gelling agent can optionally be added to the barrier layer 3 in the present invention. In particular, when the thermal transfer longitudinal image-receiving sheet 11 or 12 of the present invention is formed by the simultaneous multilayer coating method, the barrier layer 3 must contain a cooling gelling agent. By including a cooling gelling agent in each layer constituting the thermal transfer image-receiving sheet 11, a plurality of layers including a water-based receiving layer 2 and a barrier layer 3 are simultaneously formed on the base sheet 1. This is because it enables production with efficiency. Here, about the cooling gelling agent which can be used for the barrier layer 3, the thing similar to the cooling gelling agent used in the receiving layer 2 mentioned above can be used.

(Hollow particles)
Further, the barrier layer 3 may be provided with heat insulation performance by adding hollow particles to the barrier layer 3. Addition of hollow particles to the barrier layer 3 is preferable in that not only the migration of the dye diffusing from the receiving layer 2 in the barrier layer 3 can be stopped, but also a heat insulating effect can be exhibited. That is, a thermal head is added at the time of printing by the presence of a barrier layer to which hollow particles are added at a position adjacent to the receiving layer or between the receiving layer and the base sheet and close to the receiving layer. Therefore, the dye is sufficiently sublimated from the ink ribbon, and high-quality image formation is possible. The high quality image can be maintained without blurring when stored in a high temperature and high humidity environment due to the above-described effect of preventing the diffusion of the dye in the barrier layer.

  The hollow particles added to the barrier layer 3 are the same as the hollow particles used in the porous layer described later. In addition, when hollow particles are added to the barrier layer, whether or not a porous layer is separately provided between the barrier layer and the base sheet determines whether the heat transfer image-receiving sheet has heat resistance, printing temperature, or cushion. You may decide arbitrarily by sex etc.

(Other additives)
In addition to the cooling gelling agent or the hollow particles described above, as an optional compound that can be added to the barrier layer 3 in the present invention, for example, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a pigment, Examples thereof include an antistatic agent, a plasticizer, and a hot-melt material.

Although the thickness of the barrier layer 3 in the present invention is not particularly limited, it is generally in the range of 1 μm to 40 μm, in particular in the range of 1 μm to 20 μm, particularly in the range of 1 μm to 10 μm. Is preferred.

  The thermal transfer image receiving sheet 11 of the present invention described above is one aspect of the thermal transfer image receiving sheet of the present invention, and the present invention is not limited to the above laminated structure. In the thermal transfer image-receiving sheet of the present invention, at least a barrier layer and a receiving layer are provided in this order on the base sheet, but if necessary, between the base sheet and the barrier layer or between the barrier layer and the receiving layer. Between these, one or more functional layers may be provided. However, for the purpose of the present invention to prevent the dye from diffusing from the receiving layer, the barrier layer can be received in a multilayer sheet as close to the receiving layer as possible, preferably even in contact with the receiving layer. desirable. The functional layer is not particularly limited as long as it is for improving production efficiency or printing characteristics in the thermal transfer image receiving sheet.

For example, FIG. 2 shows another embodiment of the present invention. FIG. 2 is a schematic sectional view of the thermal transfer image receiving sheet 12 of the present invention. In the thermal transfer image receiving sheet 12 of the present invention, a porous layer 4 which is a functional layer for imparting heat insulation and cushioning properties to the sheet is provided between the barrier layer 3 and the base sheet 1. Although not shown, an undercoat layer may be provided between the functional layer such as the porous layer 4 and the base sheet 1 or between each layer in order to enhance the adhesion. Hereinafter, the porous layer and the undercoat layer will be described.

<Porous layer>
The porous layer 4 shown in FIG. 2 is formed between the base material sheet 1 and the barrier layer 3 and includes at least a binder resin and hollow particles, and more preferably a cooling gelling agent. It is comprised including. When the porous layer 4 forms an image using the thermal transfer image receiving sheet 12 of the present invention, the heat applied to the receiving layer 2 from the thermal head is transferred to the base sheet 1 or the like, thereby causing the base sheet to 1 is a layer for imparting heat insulation to the sheet to prevent 1 from being lost. In addition, it is desirable to form the porous layer 4 from the viewpoint of efficient use of heat so that heat from the thermal head can be efficiently used for dye sublimation during printing. In addition, the porous layer 4 has a cushioning property by containing hollow particles, and in the thermal transfer image receiving sheet 12 provided with the porous layer 4, density unevenness and white spots in highlight portions are prevented during image formation. Thus, the printing characteristics can be improved.

The heat insulating property of the porous layer 4 can be arbitrarily adjusted by the thickness of the porous layer 4 or the porosity of the porous layer mainly resulting from the amount of hollow particles contained in the porous layer 4. . The heat insulating property of the porous layer 4 can be appropriately adjusted according to the use of the thermal transfer image receiving sheet 12 of the present invention.

From the viewpoint of providing sufficient heat insulation to the porous layer 4, the thickness of the porous layer 4 is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm. At this time, the density of the porous layer 4 ^is in the range of ^{0.1g / cm 3 ~0.8g / cm 3} , among them is within the range of 0.2g ^/ cm ³ ~0.7g ^/ cm 3 It is preferable.

Similarly, the porosity of the porous layer 4 is preferably in the range of 15% to 80% from the viewpoint of giving sufficient heat insulation to the porous layer 4. The porosity is as follows:
(Void ratio of hollow particles) × (content ratio of hollow particles in the porous layer)
The value represented by

  The porous layer 4 used in the present invention may have a configuration composed of a single layer, or may have a configuration in which a plurality of layers are laminated. Here, the porous layer 4 having a configuration in which a plurality of layers are stacked may have a configuration in which layers of the same composition are stacked, or a configuration in which layers of different compositions are stacked. You may have. In particular, the porous layer 4 used in the present invention preferably has a configuration in which two layers having different compositions are laminated. This is because a more functional porous layer 4 can be obtained by adopting such a configuration.

  As an example of the case where the porous layer 4 used in the present invention has a two-layer structure, the porous layer 4 includes a porous layer A containing hollow particles a and the hollow from the base sheet 1 side. The thing which has the structure by which the porous layer B containing the hollow particle b whose hollow rate is smaller than the particle | grains a was laminated | stacked can be mentioned. By using the porous layer 4 having such a two-layer structure, the effect of improving the printing characteristics such as density unevenness at the time of printing and white spot prevention of the highlight portion can be exhibited more satisfactorily.

(Hollow particles)
The hollow particles contained in the porous layer 4 will be described. The hollow particles used in the present invention have a function of imparting heat insulation and cushioning properties to the porous layer 4. Therefore, the hollow particles are not particularly limited as long as the desired heat insulation and cushioning properties can be imparted to the porous layer 4, and foamed particles may be used, or non-foamed particles are used. You can also The expanded particles used as the hollow particles may be independent expanded particles or continuous expanded particles. Furthermore, the hollow particles used in the present invention may be organic hollow particles composed of resin or the like, or inorganic hollow particles composed of glass or the like. The hollow particles may be cross-linked hollow particles.

  Examples of the resin constituting the hollow particles include styrene resins such as crosslinked styrene-acrylic resins, (meth) acrylic resins such as acrylonitrile-acrylic resins, phenolic resins, fluorine resins, polyamide resins, and polyimide resins. Examples thereof include resins, polycarbonate resins, and polyether resins.

  The average particle diameter of the hollow particles is not particularly limited as long as the desired heat insulation and cushioning properties can be imparted to the porous layer depending on the type of resin constituting the hollow particles, etc. , Preferably in the range of 0.1 μm to 15 μm, particularly preferably in the range of 0.1 μm to 10 μm. This is because if the average particle size is too small, the amount of hollow particles used increases and the cost increases, and if the average particle size is too large, it becomes difficult to form a smooth porous layer.

  In the present invention, the amount of the hollow particles contained in the porous layer 4 is not particularly limited as long as the porous layer 4 having desired heat insulating properties and cushioning properties can be obtained. When the total solid content is 100% by weight, the proportion of hollow particles is preferably in the range of 30% to 90% by weight, and in particular, in the range of 50% to 80% by weight. Is preferred. If the content is too small, voids in the porous layer may decrease, and sufficient heat insulating properties and cushioning properties may not be obtained, and the content ratio is too large, and the weight ratio of the binder resin for forming a porous layer described later is too high. This is because if the thickness is too small, the porous layer becomes brittle and the moldability of the layer may deteriorate.

(Binder resin for porous layer formation)
As the binder resin used for forming the porous layer 4, a so-called aqueous resin that can be dispersed or dissolved in an aqueous solvent is usually used. Examples of such water-based resins include polyurethane resins such as acrylic urethane resins, polyester resins, 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. Homopolymerization of a real xylene oxide copolymer, water-soluble polyvinyl butyral, or a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260 And copolymers and the like. Moreover, you may use in combination of 2 or more types of the said resin. In the case of using materials such as gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, etc. as the binder resin for forming a porous material, these binder resins also exhibit a cooling gelling function. Therefore, it can be satisfactorily produced in the simultaneous multilayer coating method without using a cooling gelling agent described later.

  In the present invention, the amount of the binder resin contained in the porous layer 4 is appropriately determined depending on the type of hollow particles used, the heat insulation required for the thermal transfer image-receiving sheet 12, image forming conditions, and the like. When the total solid content in the porous layer 4 is 100% by weight, the ratio of the binder resin is preferably 5% to 70% by weight, and preferably 10% to 60% by weight. More preferably, it is particularly preferably 15 to 40% by weight. When there is too little content of binder resin, the porous layer 4 will become weak and there exists a possibility that layer formation may become defect. If the binder resin is too much, the content of the hollow particles is not sufficiently ensured, and the heat insulation and cushioning properties of the porous layer, which are the intended purpose, may not be ensured.

(Cooling gelling agent)
Next, the cooling gelling agent used for the porous layer 4 will be described. The cooling gelling agent used in the present invention has a property of gelling when cooled, and can be optionally added to the porous layer 4, but when the thermal transfer image receiving sheet 12 is formed by the simultaneous multilayer coating method. For this, it is necessary to contain the cooling gelling agent in the receiving layer 2 and the barrier layer 3 and also to contain the cooling gelling agent in the porous layer 4. In addition, about the kind of cooling gelling agent used for the porous layer 4, it is the same as that of the cooling gelling agent used for the receiving layer 2 mentioned above.

  Moreover, in this invention, the ratio of the hollow particle contained in the porous layer 4 and a cooling gelling agent will not be specifically limited if the porous layer which has desired heat insulation property can be formed. Especially, in this invention, it is preferable that a cooling gelatinizer exists in the range of 5-50 weight part in conversion of weight with respect to 100 weight part of solid content in a porous layer coating liquid, Especially 10 is. It is preferably within the range of ˜40 parts by weight, and more preferably within the range of 12-40 parts by weight. It is because the porous layer 4 excellent in heat insulation can be formed when the content ratio of the hollow particles and the cooling gelling agent is within the above range.

(Optional additive)
The porous layer 4 used in the present invention may contain an optional additive component as required in addition to the hollow particles, binder resin, and cooling gelling agent described above. Examples of the additive component that can be contained in the porous layer 4 include surfactants such as nonionic silicones, curing agents such as isocyanate compounds, wetting agents, and dispersing agents. .

<Underlayer>
In the thermal transfer image receiving sheet 11 of the present invention, between the base sheet 1 and the barrier layer 3, or in the thermal transfer image receiving sheet 12, in order to increase the adhesiveness between the base sheet and the porous layer 4, An undercoat layer can be further provided on the substrate (not shown). Alternatively, an undercoat layer may be provided between each layer, such as between the barrier layer and the porous layer (not shown).

(Undercoat layer resin)
The undercoat layer is not particularly limited as long as it can improve the adhesion between the base sheet 1 and the porous layer 4 or the adhesion between the porous layer 4 and the receiving layer 2 to a desired level. It is not something. In particular, in the present invention, the resin is preferably composed of a resin that can be dispersed or dissolved in an aqueous solvent. This is because each layer constituting the thermal transfer image receiving sheet is formed of a material that can be dispersed or dissolved in an aqueous solvent, thereby enabling the thermal transfer image receiving sheet to be manufactured by the simultaneous multilayer coating method. Here, as the resin for forming the undercoat layer, the same resin as the water-based resin used as the binder for forming the porous layer described for the porous layer 4 described above can be used.

  The proportion of the constituent resin in the undercoat layer is not particularly limited. Generally, when the total solid content contained in the undercoat layer is 100% by weight, the proportion of the undercoat layer constituent resin is 70% by weight or more. It is preferably 95% by weight, and more preferably 80% by weight to 90% by weight. If the content of the resin for constituting the undercoat layer is below the above range, there is a possibility that the interlayer adhesion effect required for the undercoat layer may not be sufficiently exhibited. Moreover, the upper limit of the addition amount of the undercoat layer constituting resin is prepared in relation to other additives such as a cooling gelling agent.

(Cooling gelling agent)
The addition of the cooling gelling agent in the undercoat layer is optional, but when the thermal transfer image-receiving sheet is produced by the simultaneous multilayer coating method, it is necessary to contain the cooling gelling agent in the undercoat layer together with the other layers. There is. Here, as the cooling gelling agent contained in the undercoat layer, the same cooling gelling agent used for the receiving layer 2 described above can be used.

  In the case of using the undercoat layer-containing resin and the cooling gelling agent as the undercoat layer, the ratio of the undercoat layer-constituting resin and the cooling gelling agent in the undercoat layer is When forming the subbing layer, there is no particular limitation as long as the desired viscosity characteristics can be imparted to the undercoat layer forming coating solution. In particular, in the present invention, the cooling gelling agent is preferably in the range of 1 to 100 parts by weight in terms of weight with respect to 100 parts by weight of the solid content in the coating liquid for forming the undercoat layer. It is preferably within the range of 20 to 80 parts by weight, and more preferably within the range of 25 to 75 parts by weight. When the content ratio of the cooling gelling agent is less than the above range, when the undercoat layer forming coating solution is applied onto the base sheet, for example, the adhesion with other layers may be reduced. Because there is.

  The thickness of the undercoat layer is appropriately determined depending on the position where it is formed, the type of each adjacent layer, and the like, but is generally about 0.5 μm to 10 μm.

(Other additive components)
In addition, the undercoat layer used in the present invention may further contain an optional additive component in addition to the undercoat layer forming binder resin and the cooling gelling agent. Examples of the optional additive component include a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting agent, and a dispersant.

[Method for producing thermal transfer image-receiving sheet]
Next, a method for producing the thermal transfer image receiving sheet of the present invention will be described. The thermal transfer image receiving sheet of the present invention can be generally produced using a method known as a method for producing a thermal transfer image receiving sheet. That is, the constituent layers may be sequentially laminated and manufactured on the base sheet 1 by a gravure coating method or the like. Or it can also manufacture by the simultaneous multilayer coating method of apply | coating the several layer provided on the base material sheet 1 simultaneously. Alternatively, the thermal transfer image-receiving sheet of the present invention, in addition to the above-described manufacturing method, for example, by simultaneously forming a plurality of functional layers such as a porous layer and an undercoat layer on a substrate sheet by a simultaneous multilayer coating method, It is also possible to provide a step of separately applying the receiving layer.

  Hereinafter, in order to more specifically describe an example of the method for producing the thermal transfer image receiving sheet of the present invention, an example of producing the thermal transfer image receiving sheet 12 by the simultaneous multilayer coating method will be described by being divided into a coating step, a cooling step, and a drying step. .

(Coating process)
First, an application process in which a multilayer sheet is formed by a slide coating method using a so-called slide coater will be described with reference to FIG. FIG. 3 shows that each component layer is formed on a base sheet 1 by a slide coat method using a slide coater in order to manufacture a thermal transfer image receiving sheet 12 having a porous layer 4, a barrier layer 3 and a receiving layer 2. It is a conceptual diagram which shows a mode that the coating liquid for carrying out is apply | coated simultaneously on the base material sheet 1, and the multilayer sheet 42 is formed.

The multilayer sheet 42 wraps the base sheet 1 fed from an unwinder (not shown) around the back roll 14, and on the exposed surface side, a porous layer forming layer 34, a barrier layer forming layer 33, and The receiving layer forming layer 32 is provided in this order. The three layers laminated on the base sheet 1 are the porous layer forming coating solution 24, the barrier layer forming coating solution 23, and the receiving layer forming member, which are independently filled in the coating apparatus 15. The coating liquid 22 is simultaneously formed on the substrate sheet 1 and formed. When a plurality of coating liquids are applied simultaneously with a slide coater, the temperature of each coating liquid is generally adjusted within the range of 25 ° C to 60 ° C.

From the viewpoint of coating quality, the slide coating method is excellent in film thickness uniformity, and since there is no rotating part, quality defects due to scattering of the coating liquid are unlikely to occur, and there is no friction part, so there is no friction part. There is an advantage that loss due to cutting is less likely to occur. Also, from the viewpoint of handling properties of the coating liquid, the slide coating method can use a coating liquid that is less likely to change in concentration, viscosity, and composition of the coating liquid and that has high reactivity and changes over time. The coating liquid can be used up and waste is hardly generated, and a high solid content coating liquid can be used, and the amount of solvent used can be reduced.

  In the above-described slide coating method, the coating solution for forming the porous layer, the coating solution for forming the barrier layer, and the coating solution for forming the receiving layer are usually mixed with the surfactant in the coating solution. Is added so that the difference in surface tension between the two coating liquids is within a certain range. Moreover, although the slide coat method illustrated here uses the aspect provided with three layers on the base material sheet 1, in the same slide cord method, the layers provided on the base material sheet 1 are two layers. Or it can be manufactured with four or more layers.

(Cooling process)
Next, the multilayer sheet 42 formed as described above is subjected to a cooling process. In the cooling process, each layer formed on the base sheet 1 is cooled by a cooling method 1 in which cool air is blown onto the multilayer sheet 42, and a cooling zone in which the multilayer sheet 42 is adjusted to a room temperature below a desired temperature. There is a cooling method 2 or the like for passing through. As another method, the base sheet 1 that has already been cooled in the coating step is applied to the back roll 14, and each layer is cooled at the temperature of the base sheet 1 by applying the coating liquid of each layer thereon. The cooling method 3 for simultaneously performing the coating process and the cooling treatment process, or by cooling the surface of the back roll 14 carrying the base sheet 1 and cooling each layer via the base sheet 1, The cooling method 4 etc. which perform a cooling process process simultaneously may be sufficient. Moreover, you may implement a cooling process process combining the cooling methods 1 thru | or 4 mentioned above.

  In the cooling treatment step, the temperature for forcibly cooling the coating film is usually in the range of 0 ° C. to room temperature. By performing such a cooling process, the cooling gelling agent present in the multilayer sheet 42 is cooled and gelled.

(Drying process)
The multilayer sheet 42 cooled in the cooling step is subsequently subjected to a drying step, whereby the thermal transfer image receiving sheet 12 is completed. As a method of drying the multilayer sheet 42, the multilayer sheet 42 can be dried by non-contact drying by blowing warm air of appropriate temperature while sequentially feeding the multilayer sheet 42 to a plurality of rolls. At this time, it is preferable to provide a drying path length of 500 m or longer, thereby preventing a rapid drying of the sheet, thereby forming a good thermal transfer image-receiving sheet free from drying unevenness.
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Although the said drying process implemented in manufacture of the thermal transfer image receiving sheet of this invention changes also with the material which comprises each layer, a layer structure, or the moisture content of a layer, 30 to 90 degreeC is preferable and 40 to 60 degreeC is more preferable. The method for drying the coating film in this step is not particularly limited as long as the aqueous solvent remaining in the coating film can be reduced to a predetermined amount or less within a predetermined time. About such a drying method, generally a well-known method can be used as a method of drying a coating film.

  As described above, the thermal transfer image receiving sheet of the present invention has been described with reference to some embodiments. However, the present invention is not limited to the above-described embodiments. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Preparation method of barrier layer constituting resin As barrier layer constituting resins 1 to 5, copolymers having styrene, α-methylstyrene, and acrylic acid as main components were respectively prepared, and carboxyl groups derived from acrylic acid were converted to ammonia water. By neutralizing with water, water-soluble barrier layer constituting resins 1 to 5 were obtained.
Polyester (MD-1100; manufactured by Toyobo Co., Ltd.) was used as the barrier layer-constituting resin 6, and polyester (MD-1200; manufactured by Toyobo Co., Ltd.) was used as the barrier layer-constituting resin 7.

The number average molecular weights (Mn) of the barrier layer constituting resins 1 to 7 were measured using GPC (gel permeation chromatography). The number average molecular weight (Mn) is measured using a GPC apparatus HLC-80209 (manufactured by Tosoh Corporation) as a measuring apparatus, and using G2000HXL + G3000HXL + G5000HXL as a column under measuring conditions of developing solvent THF, flow rate: 1.0 mL / min. The number average molecular weight in terms of polystyrene measured. The measurement results are shown in Table 1.

Similarly, the glass transition temperatures (Tg) of the barrier layer constituting resins 1 to 7 were measured by DSC (differential scanning calorimeter). The glass transition temperature (Tg) described here was measured by using DSC-60 (manufactured by Shimadzu Corporation) as a DSC apparatus under a temperature rising rate of 10 ° C./min, a sample weight of 10 mg, and a nitrogen atmosphere. The measurement results are shown in Table 1.

The theoretical acid values (AV) before neutralization of the barrier layer constituting resins 1 to 7 are also shown in Table 1. The theoretical acid value (AV) described in this specification means AV (mg KOH / g) = KOH amount (mg) necessary for neutralization of carboxyl groups contained in 1 g of resin.

(2) Preparation of barrier layer forming coating solution 90 parts by weight (solid content ratio in coating solution) of the barrier layer constituting resin 1 prepared or obtained above and gelatin (RR, manufactured by Nitta Gelatin Co., Ltd.) 10 parts by weight (weight ratio at the time of drying of gelatin) was used, dissolved in pure water, and diluted with pure water so that the total solid content was 17% by weight to prepare a coating solution 1 for forming a barrier layer. . Similarly, for the barrier layer constituting resins 2 to 7, 90 parts by weight and 10 parts by weight of gelatin (RR, manufactured by Nitta Gelatin Co., Ltd.) are used and dissolved in pure water to give a total solid content of 17% by weight. Thus, it diluted with the pure water so that the coating liquids 2-7 for barrier layer formation were prepared.

(3) -1 Preparation of Receptor Layer Forming Coating Liquid 1 90 parts by weight of vinyl chloride resin (Vinyl Blanc 900, manufactured by Nissin Chemical) (solid content ratio in the coating liquid) and gelatin dissolved in water (RR, manufactured by Nitta Gelatin Co., Ltd.) 10 parts by weight (weight ratio when gelatin is dried) and 10 parts by weight of a silicone release agent (KF615A, manufactured by Shin-Etsu Chemical Co., Ltd.) are dispersed and dissolved in pure water. It adjusted to pure water so that total solid content might be 25 weight%, and the coating liquid 1 for receiving layer formation was obtained.

(3) -2 Preparation of Receptor Layer-Forming Coating Liquid 2 In a 500 mL (liter) Erlenmeyer flask, 121 g of styrene, 77 g of ethyl acrylate and 2 g of acrylic acid as a copolymer-forming monomer, and Aqualon HS-10 as an emulsifier ( 1.9 g manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was added and stirred and mixed (hereinafter referred to as Composition A.) 200 g of distilled water was added to a 1 L three-necked flask and heated to 80 ° C. About 20% of the total amount of A was added and stirred for 10 minutes, after which 0.4 g of ammonium persulfate dissolved in 20 g of pure water was added and stirred for 10 minutes, and then the remaining 80% of Composition A was added with a dropping funnel. The solution was added dropwise over 3 hours and stirred for 3 hours, then cooled to room temperature and filtered through # 150 mesh (Japanese woven fabric) to obtain a styrene-acrylic receiving layer constituting resin. The number average molecular weight of the styrene acrylic resin and the glass transition temperature were measured in the same manner as in the above-described barrier layer-constituting resin, and the number average molecular weight Mw was 240000 and the glass transition temperature was 50 ° C. Styrene and From the molecular weight of ethyl acrylate and the amount used for the reaction, the respective molar ratios are 60% and 40%.
Next, 90 parts by weight of the styrene acrylic resin (solid content ratio in the coating solution) and 10 parts by weight of gelatin (RR, manufactured by Nitta Gelatin Co., Ltd.) dissolved in water (weight ratio when gelatin is dried) , 10 parts by weight of a silicone-based mold release agent (KF615A, manufactured by Shin-Etsu Chemical Co., Ltd.) is dispersed and dissolved in pure water to adjust to pure water so that the total solid content is 25% by weight. Liquid 2 was obtained.

(4) Preparation of coating solution for forming porous layer Hollow particles (HP-91, manufactured by Rohm and Haas) 75 parts by weight (solid content ratio in coating solution) and gelatin (RR, 25 parts by weight (made by Nitta Gelatin Co., Ltd.) (weight ratio when gelatin is dried) and 0.15 parts by weight surfactant (Surfinol 440, Nissin Chemical Industry Co., Ltd.) are dispersed and dissolved in pure water. And diluted with pure water so that the total solid content is 17% by weight.

[Dyeability evaluation of barrier layer constituting resin 1]
Using the barrier layer constituting resins 1 to 7, test pieces 1 to 7 each having a coating film formed by applying each barrier layer constituting resin (evaluation resin) on the base sheet by the method described later are prepared. The presence or absence of the dye dyeing property was evaluated by the dye dyeing property test shown below.

First, 90 parts by weight of the barrier layer constituting resin 1 using pure water (solid content ratio in the coating solution), 10 parts by weight of gelatin (RR, manufactured by Nitta Gelatin Co., Ltd.) (weight ratio when gelatin is dried), A silicone mold release agent (KF615A, manufactured by Shin-Etsu Chemical Co., Ltd.) 10 parts by weight (weight ratio at the time of drying) was dissolved therein, and a coating solution was prepared so that the barrier layer constituting resin had a concentration of 30% of the solution. . Next, the coating liquid is applied onto a 75 μm-thick polyethylene terephthalate base film by a bar coating method so that the film thickness after drying is 4 g / m ² and is heated to 50 ° C. And dried for 2 minutes to prepare a test piece 1.

Next, after the test piece returned to room temperature, the a * value and b * value (scale of hue and saturation in the L * a * b * color system) of the surface of the coating film were measured by Spectrono from Gretag Macbeth. Was measured under the conditions of light source D65, illumination viewing angle 2 °, density calculation ISO Status A, and no filter. Thereafter, an ink ribbon provided with a dye layer containing a cyan dye is superimposed on the coating film side, and a pressure of 10 kg / cm ² is applied by a blocking tester, and it is placed in an oven at a temperature of 40 ° C. and a humidity of 90% RH for 24 hours. Stored and then removed from the oven and left at atmospheric pressure and room temperature for 5 hours. Then, after the ink ribbon was manually pulled away from the test piece, the a * value and b * value of the coating film surface were measured by the same method as described above, and the color difference ΔEa before and after storage of the coating film according to the following (Equation 1). * b * was calculated and the dyeing property of the evaluation resin was measured and evaluated. The evaluation results are shown in Table 1.

(Equation 1) ΔEa * b * = {(a * value after storage−a * value before storage) ² + (b * value after storage−b * value before storage) ² } ^1/2

ΔEab is less than 3: None (low dyeing property)
ΔEab is 3 or more: Existence (high dyeing property)

Example 1
Using a slide coater capable of simultaneous multilayer coating, a thermal transfer image receiving sheet was prepared as follows. Resin-coated paper (STF-150, manufactured by Mitsubishi Paper Industries Co., Ltd.) is used as a base sheet, and the receiving layer forming coating solution 1 and the barrier layer forming coating solution 1 are heated to 40 ° C., respectively, and independently coated. The liquid tank was filled. And two layers were apply | coated simultaneously so that a barrier layer and a receiving layer may be laminated | stacked in this order on a base material sheet. Next, the obtained laminate was cooled at 10 ° C. or lower for 1 minute to gelatinize the gelatin contained in each layer, and further dried at 50 ° C. for 5 minutes to produce a thermal transfer image receiving sheet. did. Each layer was coated such that the film thickness upon drying was 4 g / m ² after drying the porous layer, and the film thickness after drying was 5 μm.
The layer configuration of Example 1 is summarized in Table 2. The same applies to the following examples and comparative examples.

(Examples 2 , 4, and 5)
Instead of barrier layer forming coating solution 1, the barrier layer structure forming coating solution 2, 4, except that 5 using, to produce a thermal transfer image-receiving sheet in the same manner as in Example 1, Example 2, 4 , 5 An example in which a thermal transfer image-receiving sheet was produced in the same manner as in Example 1 except that the barrier layer structure forming coating solution 3 was used is shown as Reference Example 3.

(Example 6)
The porous layer-forming coating solution is further used and filled in an independent tank of the slide coater in the same manner as other coating solutions, and the porous layer, barrier layer, and receiving layer are arranged in this order on the base sheet. A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that it was applied at the same time as Example 6.

(Examples 7 , 9, and 10)
A thermal transfer image-receiving sheet was produced in the same manner as in Example 6 except that the barrier layer-forming coating solutions 2 , 4, and 5 were used in place of the barrier layer-forming coating solution 1, and Examples 7 , 9, and 10 were produced. It was. An example in which a thermal transfer image-receiving sheet was produced in the same manner as in Example 6 except that the barrier layer structure forming coating solution 3 was used is shown as Reference Example 8.

(Example 11)
A thermal transfer image-receiving sheet was produced in the same manner as in Example 5 except that the receiving layer was formed using the receiving layer-forming coating liquid 2 instead of the receiving layer-forming coating liquid 1.

(Example 12)
A thermal transfer image-receiving sheet was produced in the same manner as in Example 10 except that the receiving layer was formed by using the receiving layer-forming coating liquid 2 instead of the receiving layer-forming coating liquid 1, and was used as Example 12.

(Comparative Examples 1 and 2)
A thermal transfer image receiving sheet was produced in the same manner as in Example 1 except that the barrier layer forming coating solution 6 or the barrier layer forming coating solution 7 was used instead of the barrier layer forming coating solution 1. These were designated as Comparative Example 1 and Comparative Example 2, respectively.

(Comparative Example 3)
A thermal transfer receiving sheet was produced in the same manner as in Example 1 except that the receiving layer was formed directly on the base material sheet without using the barrier layer forming coating solution, and was used as Comparative Example 3.

(Comparative Examples 4 and 5)
A thermal transfer image receiving sheet was produced in the same manner as in Example 6 except that the barrier layer forming coating solution 6 or the barrier layer forming coating solution 7 was used instead of the barrier layer forming coating solution 1. These were designated as Comparative Example 4 and Comparative Example 5, respectively.

(Comparative Example 6)
Comparative Example 6 comprising a base sheet, a porous layer, and a receiving layer was prepared as in Example 6 except that the barrier layer-forming coating solution was not used on the base film. Got.

(Comparative Example 7)
A thermal transfer image-receiving sheet was produced in the same manner as in Comparative Example 3 except that the receiving layer-forming coating solution 2 was used instead of the receiving layer-forming coating solution 1 to obtain Comparative Example 7.

(Comparative Example 8)
A thermal transfer image-receiving sheet was produced in the same manner as in Comparative Example 6 except that the receiving layer-forming coating solution 2 was used instead of the receiving layer-forming coating solution 1 to obtain Comparative Example 8.

  For each of Examples 1 to 12 and Comparative Examples 1 to 8 manufactured as described above, the image blur was evaluated as follows.

(Evaluation)
Using Example 1, an 18-step gradation image was printed with a sublimation thermal transfer printer CP-720 (manufactured by Canon Inc.). Thereafter, the printed matter was stored for one week in an environment of 50 ° C. and 80% RH, and the degree of blurring of the image was visually evaluated. Also, Examples 2 , 4 to 7 , 9 to 12 , Reference Examples 3 and 8, and Comparative Examples 1 to 8 were printed in the same manner as described above, and the blur of the image after storage was evaluated. The evaluation results are summarized in Table 2.

(Criteria for sensory evaluation)
○: Image blur was not observed at all visually.
X: Image blur was visually observed.

As shown in Table 2, Examples 2 and 4 to 7 including a barrier layer formed using an acrylic resin that was evaluated as having a low dye dyeing property in which ΔEab was less than 3 in the dyeing property evaluation. 9 to 12, it was confirmed that no blur was observed in the image after storage, and that a high-quality image was maintained during storage.

  On the other hand, Comparative Examples 1, 2, 4 and 5 each having a barrier layer formed using a resin having a good dye dyeing property in which ΔEab is 3 or more in the dyeing property evaluation, It was confirmed that the blur was remarkable. Further, in Comparative Examples 3 and 6 to 8 in which no barrier layer was provided, the blurring of the image after the storage was significant.

1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer image receiving sheet of the present invention. It is a conceptual diagram which shows having formed the multilayer sheet with the simultaneous multilayer coating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate sheet 2 Receiving layer 3 Barrier layer 4 Porous layer 11 Thermal transfer image receiving sheet 12 of the present invention Thermal transfer image receiving sheet 14 of the present invention Back roll 15 Coating device 22 Receiving layer forming coating solution 23 Barrier layer forming coating solution 24 Porous layer forming coating liquid 32 Receptor layer forming layer 33 Barrier layer forming layer 34 Porous layer forming layer 42 Multi-layer sheet

Claims (6)

In a thermal transfer image receiving sheet comprising a base sheet and at least a barrier layer and a receiving layer on the base sheet,
The receiving layer is composed of a dye-dyeable resin that can be dispersed or dissolved in an aqueous solvent,
The barrier layer is a styrene α-methylstyrene acrylic acid resin having a glass transition point of 40 ° C. or higher that can be dispersed or dissolved in an aqueous solvent, and the color difference ΔEab before and after storage shown in the dye dyeing property test is less than 3. A thermal transfer image-receiving sheet, characterized by comprising a resin.
Dye dyeability test: 90 parts by weight of evaluation resin, 10 parts by weight of gelatin, and 10 parts by weight of silicone release agent were diluted with pure water and applied so that the solid content concentration of the evaluation resin was 30% by weight of the solution. A working solution is prepared, and a test piece is prepared by applying the coating solution on a 75 μm thick polyethylene terephthalate base film so that the coating film after drying is 4 g / m ^2, and then at 50 ° C. The test piece is placed in a heated oven and heated for 2 minutes, and then removed from the oven. After the test piece returns to room temperature, the a * value and b * value (L * a * b * Color Hue and Saturation Scale in the color system) measured with a colorimeter under the conditions of light source D65, illumination viewing angle 2 degrees, density calculation ISO Status A, no filter, and then the coating side Ink ribs having a dye layer containing cyan dye The superposed, by applying a pressure of 10 kg / cm ² by the blocking tester, temperature 40 ° C., then stored for 24 hours in an oven at 90% RH, then, out of the oven, at atmospheric pressure at room temperature, allowed to stand for 5 hours After that, the ink ribbon was manually pulled away from the test piece, and then the a * value and b * value of the coating film surface were measured in the same manner as described above, and the color difference ΔEa * before and after storage of the coating film according to the following (Equation 1). b * is calculated and the dyeing property of the evaluation resin is measured.
(Equation 1) ΔEa * b * = {(a * value after storage−a * value before storage) ² + (b * value after storage−b * value before storage) ² } ^1/2 2. The thermal transfer image-receiving sheet according to claim 1, wherein a resin neutralized with a volatile base is used as a resin that can be dispersed or dissolved in an aqueous solvent constituting the barrier layer. The thermal transfer image receiving sheet according to claim 1 or 2, wherein the barrier layer is provided at a position in direct contact with the receiving layer. The porous layer, the barrier layer, and the receiving layer are laminated in this order on the base sheet, and the porous layer is made of a hollow particle resin that can be dispersed or dissolved in an aqueous solvent. The thermal transfer image receiving sheet according to any one of claims 1 to 3, wherein 5. The cooling gelling agent is contained in all of the receiving layer and the barrier layer laminated on the base material sheet, or further the porous layer, 5. The thermal transfer image receiving sheet described in 1. The thermal transfer image receiving sheet according to any one of claims 1 to 5, wherein the barrier layer contains gelatin.

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