JP4993124B2 - 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 method, and a thermal transfer method for the thermal transfer image receiving sheet.

In recent years, various thermal transfer methods have been widely used as color hard copies. Among these thermal transfer methods, a thermal transfer sheet in which a thermal diffusion dye (sublimation dye) as a recording material is carried on a base sheet such as a plastic film, and another base sheet such as paper or plastic film There is known a thermal diffusion type transfer system in which a thermal transfer image receiving sheet carried on each other is superposed on each other and a full color image is formed on the thermal transfer image receiving sheet by thermal transfer. In this method, a thermal head of a printer is used as a heating means, and a large number of three or four color dots are transferred to an image receiving sheet by heating for an extremely short time, and a full color image of an original is formed by the multicolored color dots. Since it uses a heat transfer dye as a color material, the image density and gradation can be freely adjusted in dot units, and a full color image exactly as it is on the original sheet can be reproduced clearly on a digital camera, video 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.
As a means for obtaining a thermal transfer image receiving sheet, for example, a method of sequentially forming a porous layer and a receiving layer on a substrate sheet by gravure coating or the like is known. However, since this method is a method of sequentially forming each layer, there is a problem that the number of steps increases. Therefore, in order to obtain a thermal transfer image-receiving sheet with a smaller number of steps, a method of simultaneously forming a plurality of layers has attracted attention.
In recent years, in thermal transfer recording systems using such dye diffusion, the printing speed has been increased, while maintaining high dye dyeing properties and excellent releasability from the thermal transfer sheet during thermal transfer, and UV irradiation. Production of a thermal transfer image-receiving sheet that is excellent in light resistance with little color change below is under investigation.

Patent Document 1 discloses a method for producing a thermal transfer image-receiving sheet in which an aqueous porous layer containing an aqueous binder and hollow particles as main components and an aqueous receiving layer containing an aqueous binder and a release agent as main components are simultaneously applied. Yes.
In Patent Document 2, in a thermal transfer image-receiving sheet having a porous layer and a receiving layer on a substrate, the porous layer contains hollow particles, and the content of the hollow particles is 65% by mass or more, In addition, a thermal transfer image receiving sheet is disclosed in which the porous layer and the adjacent layer on the receiving layer side are formed by simultaneous multilayer coating.
Patent Document 3 discloses an ink jet recording medium having a water-soluble resin as an outermost layer, and a receiving layer coating liquid mainly composed of a water-soluble resin such as polyvinyl alcohol, and hollow particles having a porosity of 30% or more. It describes about simultaneous application | coating with the lowermost layer coating liquid containing this.
Patent Document 4 discloses a heat-sensitive transfer image-receiving sheet in which a receiving layer containing a polymer latex and a porous layer containing a hollow polymer are coated on a support. The receptor layer has a solid content of the water-soluble polymer of 0.2% to 30% by mass, vinyl chlorides are preferred among the polymer latexes, and such a thermal transfer image-receiving sheet is a transfer image. It is described that a recorded image having a small change with time can be formed.

JP-A-6-171240 JP 2006-88691 A JP 2006-103040 A JP 2007-190912 A

Even when the printing speed is increased, in the thermal transfer recording system using heat transferable dye, high dye transferability, releasability from the thermal transfer sheet during transfer, and light resistance with little color change under UV irradiation Development of a thermal transfer image-receiving sheet satisfying the properties at the same time is desired.
In the present invention, at least a receiving layer and a porous layer are formed on a substrate, and the receiving layer is formed from an aqueous coating solution, which satisfies the high sensitivity of a printed matter, and further has a release property and light resistance. An object of the present invention is to provide a thermal transfer image receiving sheet improved.

The present invention has been made against the background described above, and as a thermal transfer image-receiving sheet formed on a substrate sheet by applying a porous layer and a receiving layer thereon by slide coating and then drying, the receiving layer Styrene-acrylic copolymer having at least dye-dyeing property and a resin filler, a cooling gelling agent, and a releasing agent, and the resin filler is higher than the glass transition temperature of the styrene-acrylic copolymer. It has been found that the object of the present invention can be achieved by using a material having a glass transition temperature and existing in the form of particles in the receiving layer before the thermal transfer, and has completed the present invention.

That is, the gist of the present invention is the invention described in the following (1) to (7).
(1) Thermal transfer in which a porous layer (B) containing at least hollow particles on a base sheet (A) and a receiving layer (C) for receiving a heat transferable dye from a thermal transfer sheet upon heating are formed thereon A styrene-acrylic copolymer (a) and a resin filler (b) in which the receiving layer (C) has at least a dye-dyeing property, a cooling gelling agent (c), and a release agent (image receiving sheet) d) containing,
The weight ratio [(a) / (b)] of the styrene-acrylic copolymer (a) and the resin filler (b) contained in the receiving layer (C) is 70 to 90 / 30-10, The number average molecular weight (polystyrene conversion) of the styrene-acrylic copolymer (a) is 150,000 or more, and the resin filler (b) is from the glass transition temperature (Tga) of the styrene-acrylic copolymer (a). A thermal transfer image-receiving sheet having a high glass transition temperature (Tgb) and existing in the form of particles without forming a film in the receiving layer C) before the thermal transfer.
(2) The thermal transfer image-receiving sheet as described in (1) above, wherein the styrene unit in the styrene-acrylic copolymer (a) forming the receiving layer (C) is 50 to 70 mol%.
(3) The resin filler (b) forming the receiving layer (C) is a vinyl chloride-acrylic copolymer, the vinyl chloride unit in the copolymer is 75 to 95 mol%, and the glass transition temperature. (Tgb) is 60-100 degreeC, The thermal transfer image receiving sheet as described in said (1) or (2) characterized by the above-mentioned.
(4) The thermal transfer image-receiving sheet according to any one of (1) to (3), wherein the cooling gelling agent (c) forming the receiving layer (C) is gelatin.
(5) receiving layer (C) is at least a styrene - acrylic copolymer (a) and the resin filler (b) 50 to 95 wt%, cooling the gelling agent (c) 2 to 30 wt%, and the release agent ( d) The thermal transfer image-receiving sheet according to any one of (1) to (4), which is contained in an amount of 2 to 30% by weight.
(6) the porous layer (B) is characterized in that it contains at least hollow particles (e) and cooling a gelling agent (f), thermal transfer as claimed in any one of (1) to (5) Image receiving sheet.

In the thermal transfer image receiving sheet of the present invention, at least a receiving layer (C) and a porous layer (B) are formed on a substrate sheet (A), and the receiving layer (C) is formed from an aqueous coating solution. The thermal transfer image-receiving sheet is excellent in dye transfer property, and further has excellent light resistance and improved releasability.
The thermal transfer image-receiving sheet of the present invention comprises an aqueous coating solution for forming a receiving layer (C) on a substrate sheet (A) by a slide coating method and an aqueous coating solution for forming a porous layer (B). Can be applied simultaneously, so that it can be set quickly by cooling and drying after application, and therefore, manufacture is easy.
Moreover, since the thermal transfer image receiving sheet of the present invention uses the receiving layer (C) in which the particulate resin filler (b) not formed in the vicinity of the surface is used, the thermal transfer sheet is superimposed on the thermal transfer image receiving sheet, When the thermal transfer sheet is heated by the thermal head to thermally transfer the heat transferable dye from the thermal transfer sheet to the thermal transfer image-receiving sheet, the resin filler (b) in the vicinity of the surface of the receptor layer (C) is melted and the surface of the receptor layer (C) is melted. Since it is smoothed, it is extremely excellent in releasability from the thermal transfer sheet.

Hereinafter, the “thermal transfer image receiving sheet” and the “manufacturing method of the thermal transfer image receiving sheet” of the present invention will be described.
[1] “Thermal transfer image receiving sheet” The “thermal transfer image receiving sheet” as the first aspect includes a porous layer (B) containing at least hollow particles on a base sheet (A), and a thermal transfer upon heating on the porous layer (B). Styrene-acrylic copolymer (a) and resin having a receiving layer (C) for receiving a heat transferable dye from the sheet, wherein the receiving layer (C) has at least dye-dyeing property A styrene-acrylic copolymer (a) and a resin filler (b) containing a filler (b), a cooling gelling agent (c), and a release agent (d) and contained in the receiving layer (C) The weight ratio [(a) / (b)] is 70 to 90/30 to 10, and the styrene-acrylic copolymer (a) has a number average molecular weight (polystyrene conversion) of 150,000 or more. Yes, the resin filler (b) is styrene Have acrylic copolymer a glass transition temperature (Tga) higher than the glass transition temperature of (a) (Tgb), present in said receiving layer before thermal transfer (C) particulate without film formation in It is characterized by being.

Such a thermal transfer image-receiving sheet of the present invention has a layer structure in which a porous layer (B) and a receiving layer (C) are formed on a substrate sheet (A), but the receiving layer (C). A clear layer, a primer layer, an antistatic layer, an adhesive layer and the like can be formed between the porous layer (B) and the porous layer (B). Moreover, an undercoat layer can be formed between the porous layer (B) and the base sheet (A).
Hereinafter, each layer constituting the thermal transfer image receiving sheet of the present invention will be described.

1. Receiving layer (C)
The receiving layer (C) is a layer that receives a heat transferable dye from a thermal transfer sheet during heating, and has at least a dye-stainable styrene-acrylic copolymer (a), a resin filler (b), and a cooling gel. The weight ratio of the styrene-acrylic copolymer (a) and the resin filler (b), which is formed from the agent (c) and the release agent (d) and forms the receiving layer (C) [(a ) / (B)] is 70 to 90/30 to 10, the number average molecular weight (polystyrene conversion) of the styrene-acrylic copolymer (a) is 150,000 or more, and the resin filler (b) is It has a glass transition temperature (Tgb) higher than the glass transition temperature (Tga) of the styrene-acrylic copolymer (a) and exists in the form of particles without forming a film in the receiving layer (C) before the thermal transfer. is doing.
Further, a coating liquid for forming the receiving layer (C) (hereinafter sometimes referred to as a receiving layer forming coating liquid) forms a coating liquid for forming the porous layer (B) (hereinafter referred to as porous layer formation). It may be applied onto the substrate sheet (A) by a slide coating method.
In the present invention, the receiving layer-forming coating solution contains at least a styrene-acrylic copolymer (a), a resin filler (b), a cooling gelling agent (c), and a release agent (d) in an aqueous solvent. Therefore, it is desirable to use both the styrene-acrylic copolymer (a) and the resin filler (b) that are dispersed in the aqueous solvent as a polymer latex.
Here, the “aqueous solvent” refers to a solvent containing water as a main component. The ratio of water in the aqueous solvent is 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass 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.

(1) Styrene-acrylic copolymer (a)
The styrene-acrylic copolymer (a), which is a resin contained in the receiving layer (C) used in the present invention, has a dye dyeing property, and forms a receiving layer as a polymer latex as described above. It is desirable to be added to the coating liquid.

The styrene-acrylic copolymer (a) is not particularly limited as long as it is a copolymer composed of styrene and an acrylic compound, and can be copolymerized with these essential monomers in addition to styrene and an acrylic compound. A monomer copolymerized in a small amount may also be used.
In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.
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 acid esters such as ethyl acrylate, 2-hydroxyethyl acrylate, lauryl 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, trimeta Methacrylic acid esters such as acrylic acid trimethylol propane, and the like. Among these, when a long-chain acrylic compound is used as a monomer, the light resistance is remarkably improved.

The molar ratio of styrene units to acrylic compound units ([styrene unit] / [acrylic compound]) in the styrene-acrylic copolymer (a) is preferably 50 to 70/50 to 30. Since a relatively high glass transition temperature can be obtained when the styrene unit in the styrene-acrylic copolymer (a) is 50 mol% or more, the heat resistance is improved and the light resistance is improved.
On the other hand, when the styrene unit is 70 mol% or less, excellent releasability and dyeing property can be obtained.
Further, the glass transition temperature (Tga) of the styrene-acrylic copolymer (a) used in the present invention is preferably 20 ° C. or higher, more preferably 30 ° C. or higher in consideration of workability and the like. What is 40 degreeC or more is still more preferable. As will be described later, the glass transition temperature (Tga) of the styrene-acrylic copolymer (a) may be lower than the glass transition temperature (Tga) range of 60 to 100 ° C. of the resin filler (b).

On the other hand, the minimum temperature (minimum film-forming temperature (MFT)) for the styrene-acrylic copolymer (a) to form a smooth transparent continuous coating film is -30 ° C to 90 ° C, more preferably 0 ° C to 70 ° C. A temperature of about ° C is preferred. A film-forming auxiliary may be added to control the minimum film-forming temperature.
In the present invention, the relationship between the glass transition temperature of the styrene-acrylic copolymer (a) latex and the minimum film-forming temperature is preferably such that the minimum film-forming temperature is higher than the glass transition temperature.
The styrene-acrylic copolymer (a) may be a random copolymer or a block copolymer. The styrene-acrylic copolymer (a) has a number average molecular weight (in terms of polystyrene) of 150,000 or more. If the molecular weight is less than 150,000, there arises a disadvantage that the releasability is lowered. The upper limit of the number average molecular weight (polystyrene conversion) of the styrene-acrylic copolymer (a) is practically about 250,000 from the polymerization conditions and the like.

The styrene-acrylic copolymer (a) can be produced by a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, an ionic polymerization method or the like. Since it is preferable, it is preferable to add as latex, and the emulsion polymerization method obtained as latex is most preferable.
In the present invention, “aqueous” means that 50% by mass or more of the coating liquid is water or an organic solvent (eg, methanol, ethanol, isopropanol, n-propanol, etc.) that can be uniformly mixed with water; ethylene glycol And glycols such as diethylene glycol and glycerine; esters such as ethyl acetate and propyl acetate; ketones such as acetone and methyl ethyl ketone; amides such as N, N-dimethylformamide and the like].
In the emulsion polymerization method, water or a mixed solution of water and the above-mentioned organic solvent that can be uniformly mixed with water is used as a dispersion medium, and for example, 10 to 150 parts by weight of styrene and an acrylic monomer, emulsifier with respect to 100 parts of the dispersion medium. And a polymerization initiator and the like, and a polymerization method in which polymerization is carried out at a temperature of 20 to 100 ° C. for 1 to 25 hours with stirring.
As the polymerization initiator, radical agents such as inorganic peroxides and azo compounds can be used. The addition amount of the polymerization initiator is preferably 0.2 to 3.0 parts by weight with respect to 100 parts by weight of the monomer.
As the polymerization emulsifier, an anionic surfactant, a cationic surfactant, an amphoteric surfactant and the like can be used. The addition amount of the polymerization emulsifier is preferably 0.2 to 10.0 parts by weight with respect to 100 parts by weight of the monomer. In the emulsion polymerization method, a chain transfer agent or a chelating agent can be used.

(2) Resin filler (b)
The resin filler (b) has a glass transition temperature (Tgb) higher than the glass transition temperature (Tga) of the styrene-acrylic copolymer (a), and is formed in the receiving layer (C) before the thermal transfer. The particulate resin filler (b) present in the vicinity of the surface of the receptor layer (C) is dyed together with the styrene-acrylic copolymer (a) during the thermal transfer, As long as the surface of the receiving layer (C) is smoothed as a result of melting, it can be used without particular limitation.
An example of such a resin filler (b) is a vinyl chloride copolymer. The vinyl chloride copolymer is formed by a copolymerization reaction from a vinyl chloride monomer and another monomer. Examples of the other monomer include olefins, α, β-unsaturated carboxylic acids and salts thereof. , Α, β-unsaturated carboxylic acid esters, unsaturated nitriles, vinyl ethers, vinyl esters, styrene and its derivatives, and other polymerizable monomers.

Examples of the olefins include ethylene, propylene, and other unsaturated aliphatic hydrocarbons having 4 or more carbon atoms; α, β-unsaturated carboxylic acids and salts thereof include acrylic acid, methacrylic acid, itaconic acid, and maleic acid. Sodium acrylate, potassium itaconate, etc .; α, β-unsaturated carboxylic acid esters such as acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide; unsaturated nitriles such as acrylonitrile, methacrylate Ronitrile, etc .; Vinyl ethers such as methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether, etc .; Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, etc .; Styrene and its derivatives include styrene, vinyl toluene Emissions, alpha-methyl styrene, p- chloromethylstyrene, 1,4-divinylbenzene, etc., can be exemplified.
Among the above copolymers, a vinyl chloride-acrylic copolymer is preferable, and the vinyl chloride unit of the vinyl chloride-acrylic copolymer is more preferably 75 to 95 mol%.

The resin filler (b) can be produced by a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, an ionic polymerization method and the like in the same manner as the styrene-acrylic copolymer (a). Since the receiving layer-forming coating solution is preferably aqueous, it is preferably added as a latex, and most preferably an emulsion polymerization method obtained as a latex.
Similar to the styrene-acrylic copolymer (a), the resin filler (b) obtained by the polymerization may be a random copolymer or a block copolymer. The number average molecular weight (polystyrene conversion) of the resin filler (b) is about 40,000 to 100,000 from the production conditions and the like.
The resin filler (b) has a glass transition temperature (Tgb) higher than the glass transition temperature (Tga) of the styrene-acrylic copolymer (a), and forms a film in the receiving layer (C) before the thermal transfer. Do not exist in the form of particles. The glass transition temperature (Tgb) of such a resin filler (b) is preferably 60 to 100 ° C.

The weight ratio [(a) / (b)] of the styrene-acrylic copolymer (a) and the resin filler (b) forming the receiving layer (C) is 70 to 90/30 to 10. With such a mixing ratio, with resin filler is not film formation before transfer (b) is uniformly dispersed in the form of particles in the receiving layer (C), in the vicinity of the surface of the receptive layer (C) Since there are particulates that do not form a film, the particulate portions are dyed during thermal transfer with the thermal transfer sheet, and the transfer surface of the thermal transfer image receiving sheet is smoothed by being fused by heating. At the same time, the releasability from the thermal transfer sheet is significantly improved.
From the viewpoint of dyeing property, heat resistance, light resistance and the like in the receiving layer (C), the styrene-acrylic copolymer (a) and the resin filler (b) are 50 to 95 in the receiving layer (C). It is preferably contained by weight%, more preferably 65 to 95% by weight, and particularly preferably 80 to 92% by weight.
In the present invention, a third resin may be added to the receptor layer-forming resin as long as the effects of the present invention are not impaired. The styrene-acrylic copolymer (a) and the resin filler (b ), Two or more different molecular weights may be used.

(Ii) Cooling gelling agent (c)
The cooling gelling agent (b) used in the present invention has a property of gelling when cooled, and the thermal transfer image-receiving sheet of the present invention comprises a cooling gelling agent on the base sheet (A). Since a plurality of aqueous layers including an aqueous receptive layer (C) containing can be formed simultaneously, for example, by a slide coating method, it can be manufactured with high efficiency.
Examples of the cooling gelling agent (c) include gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, and pectin, with gelatin being preferred. The cooling gelling agent (c) preferably has a viscosity at 15 ° C. in a state dissolved in water of 3 times or more, particularly 5 times or more, and more preferably 10 times or more of the viscosity at 80 ° C.

  Here, 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 being cooled, and the recovered triple helix structure. By forming a three-dimensional network starting from the helix structure, it exhibits cooling gelation characteristics. As a raw material for gelatin, gelatin obtained from collagen made from pork skin, pork bone, cow skin, cow bone, fish scale, fish skin and the like can be used. Further, the type of gelatin is not particularly limited, and lime-processed gelatin, acid-processed gelatin, and so-called derivative gelatin in which all or part of amino groups of gelatin are blocked can also be used.

The derivative gelatin is preferably a derivative gelatin in which the amino group of gelatin is blocked, and includes those obtained by isocyanate addition, acylation, or deamination. Preferred derivative gelatin is gelatin obtained by adding gelatin and phenyl isocyanate, alkyl isocyanate, or the like, or a product obtained by reacting acid anhydride such as phthalic anhydride or acid chloride such as phthalic chloride. The ratio of amino group blocking in gelatin is 70% or more, preferably 80% or more, particularly preferably 90% or more of the amino group. The film using gelatin may be hardened with a hardener in a range satisfying water solubility. The gelatin used in the present invention may have a molecular weight of 10,000 to 1,000,000. The gelatin used in the present invention may contain anions such as Cl- and SO ₄ ^{2- and} may contain cations such as Fe ²⁺ , Ca ²⁺ , Mg ²⁺ , Sn ²⁺ and Zn ^2+. . It is preferable to add gelatin dissolved in water.

  Gelatin manufactured by Nitta Gelatin Co., Ltd. (trade names: MJ, R, APH-200, etc.), Gelatin manufactured by Nippi Co., Ltd. (trade names: DP, DG, DB, MAX-F, etc.), Gelais ( Co., Ltd. gelatin (trade names: AU, AU-P, AU-G, AU-S, etc.).

  The content of the cooling gelling agent (c) in the receptor layer (C) of the present invention is such that the receptor layer-forming coating used to form the receptor layer (C) when the thermal transfer image-receiving sheet of the present invention is produced. There are no particular limitations as long as the desired surface tension, viscosity characteristics, and the like can be imparted to the working fluid. For these reasons, the cooling gelling agent (c) is preferably contained in the receptor layer (C) in an amount of 2 to 30% by mass, more preferably 2 to 25% by mass, and even more preferably 2 to 20% by mass. . When the content ratio of the cooling gelling agent (c) is less than 2% by mass, for example, unevenness or the like is likely to occur when the receiving layer forming coating liquid is applied and dried on the base sheet (A). On the other hand, if it exceeds 30% by mass, the dyeing property of the dye may be lowered during image formation, and the image density may be lowered.

(3) Release agent (d)
In the receiving layer (C), the release agent (d) is contained in the styrene-acrylic copolymer (a) and the cooling gelling agent (b). By adding the release agent (d) to the receiving layer (C), there is an effect of preventing fusion with the thermal transfer sheet when the thermal transfer image receiving sheet is thermally transferred.
Examples of the release agent (d) used in the receiving layer (C) include conventionally known release agents such as solid waxes such as silicone oil, polyethylene wax, amide wax, and Teflon (registered trademark) powder, fluorine-based, phosphorus Any of acid ester surfactants, silicones and the like can be used. Particularly preferred release agent (d) is a modified silicone, and specific examples thereof include those shown in the following (a) to (f).
(B) Modified silicone oil side chain type (b) Modified silicone oil both ends type (c) Modified silicone oil one end type (d) Modified silicone oil side chain both ends type (e) Silicone graft acrylic resin (f) Methylphenyl Silicone oil

  Modified silicone oils are divided into reactive silicone oils and non-reactive silicone oils. Examples of the reactive silicone oil include amino modification, epoxy modification, carboxyl modification, carbinol modification, methacryl modification, mercapto modification, phenol modification, one-end reactivity, and different functional group modification. Examples of the non-reactive silicone oil include polyether modification, methylstyryl modification, alkyl modification, higher fatty acid ester modification, hydrophilic special modification, higher alkoxy modification, higher fatty acid modification, and fluorine modification.

  One or more release agents (d) are used. Moreover, it is preferable that 2-30 mass% of mold release agents (d) are contained in a receiving layer (C), 2-25 mass% is more preferable, and 2-20 mass% is still more preferable. When the content of the release agent (c) is less than 2% by mass, there is a possibility that the thermal transfer sheet and the thermal transfer image receiving sheet are fused and cannot be printed normally when a printed product is produced using the thermal transfer image receiving sheet. On the other hand, if it exceeds 30% by mass, the print sensitivity may be lowered when a printed product is produced using the thermal transfer image-receiving sheet of the present invention.

(4) Other additives In addition to the above, optional additives that can be added to the receiving layer (C) in the present invention include, for example, surfactants, antioxidants, ultraviolet absorbers, light stabilizers, Examples thereof include a filler, a pigment, an antistatic agent, a plasticizer, and a hot-melt material.
The surfactant has an action of improving the dispersibility of the hydrophobic compound when the receptor layer is formed by a slide coating method or the like. As such a surfactant, various surfactants such as phosphate ester type surfactants can be used. In addition, it is desirable that the amount of the surfactant added is about 0.5 to 3% by mass in the receiving layer (C) on a solid basis in order to effectively exhibit the above-described action.

(5) Receptor Layer Components and Thickness As described above, the receptor layer (C) contains at least 50 to 95% by weight of a styrene-acrylic copolymer (a) and a resin filler (b), a cooling gelling agent ( c) 2 to 30% by weight and release agent (d) 2 to 30% by weight are preferably contained.
The thickness of the receiving layer (C) used in the present invention is the resin forming the receiving layer (styrene-acrylic copolymer (a) and resin filler (b)) (hereinafter sometimes referred to as receiving layer forming resin). There is no particular limitation as long as it is within a range in which a desired image density can be expressed depending on the type of the material, but it is preferably within a range of 0.5 μm to 20 μm, more preferably 1 μm to 20 μm, and more preferably 1 μm to 15 μm Is more preferable.

2. Porous layer (B)
The porous layer (B) used in the present invention is formed on the base sheet (A) and contains at least hollow particles (e) and a cooling gelling agent (f). Thermal insulation and cushion that suppresses heat applied from the thermal head to the receiving layer (C) from the thermal head to the base sheet (A) when forming an image from the thermal transfer sheet using the sheet. It has sex.
By using such a porous layer (B) for the thermal transfer image receiving sheet of the present invention, the printing characteristics of the thermal transfer image receiving sheet can be made more excellent.

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

Examples of the resin constituting the hollow particles (e) include styrene resins such as crosslinked styrene-acrylic resins, (meth) acrylic resins such as acrylonitrile-acrylic resins, phenolic resins, fluorine resins, polyamide resins, Examples thereof include a polyimide resin, a polycarbonate resin, and a polyether resin.
The average particle diameter of the hollow particles (e) is particularly limited as long as desired heat insulating properties and cushioning properties can be imparted to the porous layer (B) according to the type of resin constituting the hollow particles (e). However, it is usually preferably 0.1 μm to 15 μm, more preferably 0.1 μm to 10 μm. If the average particle size is too small, the amount of hollow particles (e) used increases and the cost increases. If the average particle size is too large, it may be difficult to form a smooth porous layer (B). . These hollow polymers preferably have a hollow ratio of about 30 to 80%, and those having a hollow ratio of 2 or more can also be used in combination.

  In the present invention, the amount of the hollow particles (e) contained in the porous layer (B) is not particularly limited as long as a porous layer having desired heat insulating properties and cushioning properties can be obtained. 50 mass%-90 mass% are preferable, and 60 mass%-85 mass% are more preferable. If the content of the hollow particles (e) is too small, there are less voids in the porous layer (B), and sufficient heat insulating properties and cushioning properties may not be obtained. On the other hand, if the content is too large, There arises a disadvantage that the adhesiveness is lowered.

(2) Cooling gelling agent (f)
The cooling gelling agent (f) used in the present invention has a property of gelling when cooled. The thermal transfer image-receiving sheet of the present invention is coated with a cooling gelling agent on the base sheet (A). Since a plurality of layers including the aqueous receptive layer (C) and the porous layer (B) can be formed at the same time, it can be produced with high efficiency by, for example, a slide coating method.
Such a cooling gelling agent (f) is not particularly limited as long as it has cooling gelling properties.

  The cooling gelling agent (f) used for the porous layer (B) is essentially the same as the cooling gelling agent (b) exemplified in the receiving layer (C), and the cooling gelling agent (b) Any of those described in the explanation section of can be suitably used. Moreover, as a cooling gelling agent (f) used for a porous layer (B), only 1 type of cooling gelling agent may be used, or 2 or more types of cooling gelling agents may be used. .

  The ratio of the cooling gelling agent (f) and the hollow particles (e) contained in the porous layer (B) forms a porous layer having desired heat insulating properties and cushioning properties. The coating liquid for forming a porous layer used for forming the coating layer is not particularly limited as long as desired viscosity characteristics can be imparted to the coating liquid. Among them, in the porous layer (B), the cooling gelling agent (f) is preferably 10 to 50% by mass, more preferably 20 to 40% by mass in the porous layer (B). When the content of the cooling gelling agent (f) is less than 10% by mass, for example, unevenness or the like is likely to occur when the receiving layer forming coating solution is applied and dried on the base sheet. On the other hand, when it exceeds 50 mass%, there exists a possibility that heat insulation and a cushioning property may fall, for example.

(3) Other additives The porous layer (B) used in the present invention contains at least the cooling gelling agent (e) and the hollow particles (d), and optionally added as necessary. An agent can be included. Examples of the optional additive that can be contained in the porous layer (B) include the cooling gelling agent (e) acting as a binder for forming the porous layer. Examples include layer forming binders, nonionic silicone surfactants, curing agents such as isocyanate compounds, wetting agents, and dispersing agents.
As the other porous layer forming binder, an aqueous resin is usually used. Examples of such water-based resins include polyurethane resins such as acrylic urethane resins, polyester resins, polyethylene oxysides, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, polyacrylic acid and salts thereof, and casein. , Xanthene gum, locust bean gum, alginic acid, gum arabic, polyalkylenoxide copolymer described in JP-A-7-195826 and 7-9757, water-soluble polyvinyl butyral, or JP Examples thereof include homopolymers and copolymers of vinyl monomers having a carboxyl group or a sulfonic acid group described in JP-A-62-245260. Moreover, you may use in combination of 2 or more types of the said resin.

(4) Porosity, thickness, etc. of porous layer (B) When forming an image using the thermal transfer image-receiving sheet of the present invention, the porous layer (B) is added from the thermal head to the receiving layer (C). It has heat insulation that reduces the amount of heat transferred to the base sheet (A) side. The heat insulation property of the porous layer (B) used in the present invention can be appropriately adjusted according to the use of the thermal transfer image-receiving sheet of the present invention. Here, the heat insulation of a porous layer (B) can be adjusted to arbitrary ranges by changing the thickness of a porous layer (B), for example.
The heat insulation property of the porous layer (B) can also be controlled by the porosity of the porous layer (B). Here, the porosity of the porous layer (B) used in the present invention is preferably in the range of 15 to 80%. In addition, the said porosity shall point out the value represented by (the porosity of a hollow particle) x (the content rate of the hollow particle in a porous layer (B)).

The thickness of the porous layer (B) used in the present invention is preferably within the range of 10 μm to 100 μm, and more preferably 10 μm to 50 μm. The density of the porous layer (B) is preferably, for example ^{0.1g / cm 3 ~0.8g / cm 3} , 0.2g / cm 3 ~0.7g / cm 3 is more preferable.
The porous layer (B) used in the present invention may have a structure composed of a single layer, or may have a structure in which a plurality of layers are laminated. Here, the porous layer (B) having a configuration in which a plurality of layers are stacked may have a configuration in which layers having the same composition are stacked, or layers having different compositions are stacked. It may have a configuration. In particular, the porous layer (B) used in the present invention preferably has a structure in which two layers having different compositions are laminated. By setting it as such a structure, it becomes possible to obtain a more functional porous layer (B).

  As an example of the case where the porous layer (B) used in the present invention has a two-layer structure, the porous layer (B) is a porous material containing hollow particles (e1) from the base sheet (A) side. And a porous layer (B2) containing hollow particles (e2) having a hollow ratio smaller than that of the hollow particles (e1). By using the porous layer (B) having such a configuration, there is an advantage that image density unevenness and white spots in highlight portions can be prevented during printing.

3. Base sheet (A)
The base sheet (A) used in the present invention has a function of supporting the porous layer (B) and the receiving layer (C) described above. The substrate sheet (A) is not particularly limited as long as it has a desired heat resistance depending on the printing temperature or the like when forming an image from the thermal transfer sheet by thermal transfer. Specifically, , Resin-coated paper, resin film base, paper base, and the like. Among these, resin-coated paper is preferable.
(I) Resin-coated paper Resin-coated paper is usually one in which a base resin layer is laminated 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 thickness of the base paper is, for example, 10 μm to 1000 μm, and among these, 50 μm to 300 μm is more preferable.

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 resin for forming the base resin layer is preferably a resin having a small neck-in and a good drawdown property. For example, a polyolefin resin, a polystyrene resin, a vinyl resin, a polyester resin, an 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, or a film or sheet formed by adding a pigment, a filler or the like to the resin. It may be. Further, the resin may be one obtained by blending an additive such as a modifier to improve adhesiveness. As said modifier, the Mitsui Chemicals Co., Ltd. product name: Olefin-type copolymers, such as Tuffmer, etc. can be mentioned, for example.
The resin-coated paper can be produced by a known laminating method such as dry lamination, wet lamination, or extrusion. Each of the above layers can be appropriately subjected to primer treatment or corona discharge treatment for the purpose of improving interlayer adhesion.
The total thickness of the resin-coated paper is, for example, 10 μm to 1000 μm, and among these, 50 μm to 300 μm is more preferable.

(Ii) Resin film substrate Examples of the resin film substrate used in the present invention include polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, and 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, tetrafluoro Examples include ethylene-ethylene, tetrafluoroethylene-hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride. Rukoto can. Among these, in the present invention, polyethylene terephthalate and polypropylene resin can be preferably used.
As thickness of the said resin-made film base material, 20 micrometers-100 micrometers can be illustrated, for example, Among these, 25 micrometers-60 micrometers are more preferable, and 30 micrometers-50 micrometers are still more preferable.

(Iii) Paper base material The paper base material used in the present invention includes, for example, condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), and high-quality paper. Art paper, coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, cellulose fiber paper, and the like.
Although it does not specifically limit as thickness of the said paper-made base material, For example, 80 micrometers-400 micrometers can be illustrated, for example, 100 micrometers-300 micrometers are preferable, and 100 micrometers-210 micrometers are more preferable.

4). Arbitrary Layer Configuration The thermal transfer image-receiving sheet of the present invention comprises at least a base sheet (A), a receiving layer (C), and a porous layer (B) formed between the receiving layer (C) and the base sheet (A). However, it may have any other configuration as necessary. Examples of such other configurations include an undercoat layer (D) formed between the porous layer (B) and the base sheet (A), and a porous layer (B) and a receiving layer (C). And a primer layer (E) formed between the two. Hereinafter, each of these layers used in the present invention will be described.

(1) Primer layer (E)
The primer layer (E) that can be used in the present invention is formed between the porous layer (B) and the receiving layer (C), and the thermal transfer image receiving sheet of the present invention in a high temperature and high humidity environment. The dye has a function of preventing image migration to the porous layer (B) side and improving image storage stability. The primer layer (E) is a layer mainly composed of a thermoplastic resin forming the primer layer (E) (hereinafter sometimes referred to as a primer layer forming resin), a cooling gelling agent, and polyvinyl alcohol (PVA). It is also possible to form a layer mainly composed of a water-soluble polymer.
(I) Layer mainly composed of primer layer forming resin and cooling gelling agent The primer layer (E) is preferably formed from a layer mainly composed of a primer layer forming resin and a cooling gelling agent. The primer layer forming resin is used as a coating liquid for forming the water-based primer layer (E) together with the cooling gelling agent (hereinafter sometimes referred to as primer layer forming coating liquid) on the base sheet (A). In addition, it is preferably formed by a slide coating method together with a coating solution for forming a porous layer (B) and a receiving layer (C), and therefore, it is preferably used by emulsifying in an aqueous solvent.

(I-1) Primer layer forming resin Examples of the primer layer forming resin include polyolefin resins, polyvinyl resins, polyester resins, polyurethane resins, polycarbonate resins, polyamide resins, poly (meth) acrylic acid resins, and cellulose derivative resins. Examples thereof include a resin or a polyether resin. In the present invention, any of these resins can be suitably used, but among them, it is preferable to use a polyvinyl resin. Examples of the polyvinyl resin include vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylic compound copolymer, ethylene-vinyl chloride-acrylic ester copolymer, ethylene-vinyl acetate-vinyl chloride copolymer, etc. Can be mentioned.

(I-2) Cooling gelling agent The primer layer (E) preferably contains a cooling gelling agent. The cooling gelling agent used for the primer layer (E) is the same as that described in the section “(1) Receiving layer (C)”, and the description thereof is omitted here.
When using the primer layer (E) containing the primer layer forming resin and the cooling gelling agent, the ratio of the primer layer forming resin and the cooling gelling agent is determined when the primer layer (E) is formed. The primer layer forming coating solution is not particularly limited as long as it is within a range in which desired viscosity characteristics can be imparted. For example, in the primer layer forming coating solution, it is preferable that the cooling gelling agent is contained in a solid content in a proportion of 1 to 50% by mass. When the content of the cooling gelling agent is less than the above range, for example, unevenness or the like may easily occur when the receiving layer forming coating liquid is applied on the base sheet, If the range is exceeded, for example, the adhesion to other layers may be reduced. A more preferable content of the cooling gelling agent is 2 to 40% by mass, and a more preferable content is 4 to 75% by mass.

(Ii) Water-soluble polymer As a water-soluble polymer that can be used for forming the primer layer (E), an acrylic polymer such as sodium polyacrylate, polyacrylamide, and a copolymer thereof such as a vinyl polymer such as polyvinyl Other polymers such as alcohol, polyvinylpyrrolidone and polyvinylpyrrolidone copolymer include polyethylene glycol, polypropylene glycol, polyisopropylacrylamide, polymethylvinyl ether, polyethyleneimine, maleic acid copolymer, maleic acid monoester copolymer, water-soluble Such as reactive polyester.
Among the water-soluble polymers, polyvinyl alcohol, its completely saponified product, partially saponified product, and modified polyvinyl alcohol are preferably used. Polyvinyl alcohol can be adjusted in viscosity and stabilized by an additive.

(Iii) Other additives In addition to the primer layer-forming resin and the cooling gelling agent, the primer layer (E) includes, for example, nonionic silicone surfactants, curing agents such as isocyanate compounds, and wetting agents. , And a dispersant may be contained.
(Iv) Thickness of primer layer (E) The thickness of the primer layer (E) is not particularly limited, but is preferably 1 μm to 40 μm, more preferably 1 μm to 20 μm, more preferably 1 μm to 10 μm, for example. Further preferred.

(2) Undercoat layer (D)
The undercoat layer (D) that can be used in the present invention is formed between the base sheet (A) and the porous layer (B), and is composed of the base sheet (A) and the porous layer (B). It has a function of improving adhesiveness.
The undercoat layer (D) is not particularly limited as long as the adhesion between the base sheet (A) and the porous layer (B) can be improved to a desired level. It is preferably formed from a resin layer (hereinafter also referred to as an undercoat layer forming resin), a cooling gelling agent and a main layer, but (ii) a water-soluble polymer can also be used. It is.
In addition, (i) undercoat layer forming resin and cooling gelling agent, and (ii) water-soluble polymer in the undercoat layer (D) are the primer layer forming resin and cooling gel described in the primer layer (E). Since they are the same as the agent and the water-soluble polymer, description thereof is omitted.
For the undercoat layer (D), in addition to the undercoat layer forming resin and the cooling gelling agent, for example, nonionic silicone surfactants, curing agents such as isocyanate compounds, wetting agents, dispersants, etc. Etc. The curing agent is particularly effective when, for example, a thermoplastic resin having active hydrogen is used as the undercoat layer forming resin.

The coating liquid for forming the undercoat layer (hereinafter sometimes referred to as an undercoat layer forming coating liquid) may contain hollow particles. When hollow particles are contained in the undercoat layer-forming coating solution, the hollow particles are preferably in the range of 20% by mass to 90% by mass, more preferably 40% by mass to 80% by mass as the solid content. preferable. In addition, about the hollow particle used for the said undercoat layer forming coating liquid, since it is the same as that used for the porous layer (B) mentioned above, description here is abbreviate | omitted.
As solid content concentration in undercoat layer forming coating liquid, 2 mass%-10 mass% are more preferable within the range of 1 mass%-50 mass%, for example. If the solid content concentration is too low, the drying time may become longer, and if the solid content concentration is too high, the storage stability of the coating liquid may be lowered and the viscosity may increase.

5. Production of thermal transfer image-receiving sheet of the present invention The thermal transfer image-receiving sheet of the present invention can be produced by a gravure method, a curtain method, a slide method, or the like.
As described above, the thermal transfer image-receiving sheet of the present invention comprises at least a porous layer (B), a receiving layer (C) and the like as an aqueous porous layer-forming coating solution and a receiving layer-forming coating solution, respectively. Since it can form simultaneously on a material sheet (A), it is preferable to manufacture by the slide coat method among the said manufacturing methods. By adopting the slide coating method, manufacturing is extremely easy and highly efficient manufacturing is possible. A slide coating method will be described below as a specific example of a method for producing a thermal transfer image receiving sheet, but the following description can also be applied to a gravure method and a curtain method.

[2] Manufacturing Method of Thermal Transfer Image Receiving Sheet Next, a slide coating method will be described as a specific example of the thermal transfer image receiving sheet of the present invention.
In the method for producing a thermal transfer image-receiving sheet of the present invention, (i) a plurality of layers containing at least a porous layer forming coating solution and a receiving layer forming coating solution are simultaneously applied on the substrate sheet (A). A multilayer coating step, (ii) a cooling treatment step for cooling the coating film comprising a plurality of layers formed on the substrate sheet (A), and (iii) drying the coating film cooled in the cooling treatment step. It can be manufactured by a drying process.
Hereafter, each said process is demonstrated in order.
1. Simultaneous multilayer coating step As described above, the simultaneous multilayer coating step simultaneously coats a plurality of layers including at least a coating solution for forming a porous layer and a coating solution for forming a receiving layer on the substrate sheet (A). It is a process.

(1) Receiving layer forming coating solution The receiving layer forming coating solution used in the simultaneous multilayer coating step is at least a styrene-acrylic copolymer (a), a resin filler (b), and a cooling gelling agent (c). ) And a release agent (d).
Here, regarding the styrene-acrylic copolymer (a) and the resin filler (b), the cooling gelling agent (c), and the release agent (d) used in the simultaneous multilayer coating step, the above “[1] Since it is the same as that described in the section “(1) Receiving layer (C)”, the description thereof is omitted here.
Since the coating solution for forming the receiving layer used in the simultaneous multilayer coating step is aqueous, an aqueous solvent is used. Here, the “aqueous solvent” used in the simultaneous multilayer coating step is as described above.

The viscosity of the receiving layer-forming coating solution used in the simultaneous multilayer coating step is not particularly limited as long as it is not mixed with other coating solutions that are simultaneously coated on the base sheet (A) in the step. It is not something. Especially in this process, in 40 degreeC, the inside of the range of 1 mPa * s-50 mPa * s is preferable, 5 mPa * s-50 mPa * s are more preferable, 7 mPa * s-40 mPa * s are still more preferable.
In the present invention, the viscosity of the receiving layer-forming coating solution and the like can be measured using, for example, a small vibration viscometer (VIBRO VISCOMETER CJV5000, manufactured by A & D). The solid content concentration of the coating liquid for forming the receiving layer used in the simultaneous multilayer coating step is not particularly limited as long as the viscosity is within a desired range, but 10 mass% to 50 mass in particular. %, Particularly in the range of 10% by mass to 40% by mass. 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. Is produced.

Further, the styrene-acrylic copolymer (a) and the resin filler (b), the cooling gelling agent (c), and the release agent (d) contained in the receiving layer forming coating liquid are as described above. Thus, the components in the receiving layer (C) after drying are styrene-acrylic copolymer (a) and resin filler (b) 50 to 95% by weight, cooling gelling agent (c) 2 to 30% by weight, In addition, it is desirable to blend so as to contain 2 to 30% by weight of the release agent (d). When the content ratio of the cooling gelling agent (c) is less than 2% by weight, for example, unevenness or the like may easily occur when the receiving layer forming coating solution is applied and dried on the substrate sheet. Further, if it exceeds 30% by weight, for example, the dyeing property of the dye may be lowered during image formation, and the image density may be lowered.
In addition to the receiving layer forming resin and the cooling gelling agent (c), examples of additives that can be added to the receiving layer forming coating solution include an antioxidant, an ultraviolet absorber, a light stabilizer, Examples thereof include a filler, a pigment, an antistatic agent, a plasticizer, a hot-melt material, and a surfactant. Such additives are the same as those described in the section “[1] Thermal transfer image-receiving sheet”, and thus description thereof is omitted here.

(2) Porous layer forming coating liquid The porous layer forming coating liquid used in the simultaneous multilayer coating step contains at least hollow particles (e) and a cooling gelling agent (f), which are used as an aqueous solvent. Dispersed and dissolved.
The hollow particles (e) and the cooling gelling agent (f) used in the coating liquid for forming the porous layer and the blending ratio thereof are described in “[1] Thermal transfer image-receiving sheet, (2) Porous”. Since it is the same as that described in the section of “Layer (B)”, the description is omitted here. Further, the aqueous solvent is the same as that used in the receiving layer forming coating solution, and thus the description thereof is omitted here.

The viscosity of the coating liquid for forming a porous layer used in the simultaneous multilayer coating process is not particularly limited as long as it does not mix with other coating liquids applied simultaneously on the base sheet in the simultaneous multilayer coating process. is not. Especially, in a simultaneous multilayer coating process, 1 mPa * s-50 mPa * s are preferable at 40 degreeC, and 5 mPa * s-40 mPa * s are more preferable. Moreover, it is preferable that the viscosity in 20 degreeC is 0.5 Pa.s or more, and it is especially preferable that it is 1 Pa.s or more.
The solid content concentration of the coating liquid for forming a porous layer used in the simultaneous multilayer coating step is not particularly limited as long as the viscosity can be adjusted within the above range, but is preferably 10% by mass to 50% by mass. More preferably, it is 40% by mass. If the solid content concentration is less than 10% by mass, the solution viscosity becomes low, causing inconvenience during coating, and drying takes time. On the other hand, if it exceeds 50% by mass, the storage stability of the coating liquid is increased. The viscosity decreases and the viscosity increases, which may cause inconvenience during coating.

Furthermore, the proportion of the hollow particles (e) contained in the porous layer forming coating solution in the entire solid content is described in the section “[1] Thermal transfer image-receiving sheet, (2) Porous layer (B)”. Similarly, the porous layer-forming coating solution used in the simultaneous multilayer coating step may contain other additives other than the hollow particles (e) and the cooling gelling agent (f). Examples of such other additives include a binder for forming a porous layer, a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting agent, and a dispersing agent.
Here, since these additives are the same as those described in the section “[1] Thermal transfer image-receiving sheet”, description thereof is omitted here.

(3) Base material sheet The base material sheet used in the simultaneous multilayer coating process has a function of supporting the coating film formed in the process. The base material sheet used in the simultaneous multilayer coating step is the same as that described in the above section “[1] Thermal transfer image receiving sheet”, and thus the description thereof is omitted here.

(4) Other layers In the simultaneous multilayer coating step, in addition to the porous layer forming coating solution and the receiving layer forming coating solution, a primer layer forming coating solution and / or When applying the coating liquid for forming the undercoat layer at the same time, the surface tension difference between the adjacent coating liquids is usually within a certain range so that these coating liquids do not mix with each other during application. Adjusted.

(4-1) Primer layer forming coating solution The primer layer forming coating solution forms a primer layer (E) provided between the porous layer (B) and the receiving layer (C). By providing the primer layer (E) excellent in heat resistance, it has an effect of suppressing blurring of an image during image storage in a high temperature and high humidity environment.
The primer layer forming resin is not particularly limited as long as it has heat resistance, can be dispersed and dissolved in an aqueous solvent, and has a glass transition temperature of 20 ° C. or higher.
The primer layer forming coating solution used in the simultaneous multilayer coating step is not particularly limited as long as the primer layer (E) having predetermined properties can be formed. In particular, in the simultaneous multilayer coating process, the primer layer forming resin and the cooling gelling agent are dispersed and dissolved in an aqueous solvent to adjust the surface tension and viscosity, so that the primer layer forming coating solution is applied simultaneously. Mixing with other coating liquids can be effectively prevented.

The primer layer-forming resin, the cooling gelling agent, and the blending ratio thereof are the same as those described in the section “[1] Thermal transfer image-receiving sheet, 4. Arbitrary layer configuration, (2) Primer layer (E)”. It is.
10 mass%-50 mass% are preferable, and, as for the solid content concentration of the coating liquid for primer layer formation used for a simultaneous multilayer coating process, 10 mass%-25 mass% are more preferable. If the solid content concentration is less than 10% by mass, the solution viscosity is too low and the drying time may be long. On the other hand, if the solid content concentration exceeds 50% by mass, the storage stability of the coating liquid decreases and the viscosity increases. This may cause inconvenience in coating.
The viscosity of the primer layer-forming coating solution is not particularly limited as long as it does not mix with another coating solution that is simultaneously applied onto the porous layer (B) in the simultaneous multilayer coating step. Especially in this process, the inside of the range of 1 mPa * s-100 mPa * s is preferable at 40 degreeC, 7 mPa * s-70 mPa * s are more preferable, 10 mPa * s-50 mPa * s are still more preferable.

(4-2) Undercoat layer forming coating solution The undercoat layer forming coating solution used in the simultaneous multilayer coating step is applied so as to be in contact with the substrate sheet (A), and the substrate sheet (A). It can be used to form an undercoat layer (D) provided for improving the adhesion between the porous layer (B) and the porous layer (B). By providing the undercoat layer (D), the adhesion between the base sheet and the porous layer (B) of the thermal transfer image-receiving sheet produced according to the present invention becomes more excellent.
As the coating solution for forming the undercoat layer used in the simultaneous multilayer coating process, an undercoat layer (D) capable of improving the adhesion between the base sheet (A) and the porous layer (B) to a desired level is formed. There is no particular limitation as long as it is possible. In particular, in this step, it is usually preferable to use a resin in which an undercoat layer-forming resin and a cooling gelling agent are dispersed and dissolved in an aqueous solvent. By using the coating liquid for forming the undercoat layer having such a composition, it can be effectively prevented from being mixed with another coating liquid applied simultaneously with the coating liquid for forming the undercoat layer. .

The undercoat layer-forming resin is particularly limited as long as it can improve the adhesion between the base sheet (A) and the porous layer (B) and can be dissolved and dispersed in an aqueous solvent. Although not intended, a water-based resin is usually used.
The cooling gelling agent used in the undercoat layer forming coating solution is not particularly limited as long as it can impart desired viscosity characteristics to the undercoat layer forming coating solution. As such a cooling gelling agent, those similar to those used in the porous layer forming coating solution can be used.
Moreover, the same thing as what is used for the said coating liquid for porous layer formation can be used also about the aqueous solvent used for the said undercoat layer forming coating liquid.

The undercoat layer forming resin and the cooling gelling agent contained in the undercoat layer forming coating liquid are described in “[1] Thermal transfer image receiving sheet, 4. Arbitrary layer structure, (2) Undercoat layer”. This is the same as described in the section (D).
In addition to the undercoat layer-forming resin and the cooling gelling agent, examples of additives that can be added to the undercoat layer-forming coating solution include nonionic silicone-based surfactants, isocyanate compounds, and the like. The curing agent, wetting material, dispersing agent and the like can be mentioned. The curing agent is particularly effective when, for example, a thermoplastic resin having active hydrogen is used as the undercoat layer forming resin.

In the simultaneous multilayer coating step, the solid content concentration of the coating liquid for forming the undercoat layer is, for example, preferably 1% by mass to 50% by mass, and more preferably 2% by mass to 10% by mass. If the solid content concentration is less than 2% by mass, the solution viscosity is too low, and drying takes a long time. On the other hand, if the solid content concentration exceeds 50% by mass, the storage stability of the coating liquid decreases and the viscosity increases. It may cause inconvenience in coating.
The viscosity of the coating liquid for forming the undercoat layer is not particularly limited as long as it does not mix with other coating liquids applied simultaneously on the base sheet (A) in the simultaneous multilayer coating process. . Especially, in this process, it is within the range of 1 mPa · s to 40 mPa · s at 40 ° C., more preferably 5 mPa · s to 30 mPa · s, and further preferably 7 mPa · s to 25 mPa · s.

(5) Simultaneous multilayer coating method Next, a method of simultaneously coating a porous layer forming coating solution, a receiving layer forming coating solution and the like on the substrate sheet (A) will be described.
As a method of simultaneously applying a plurality of layers including a receiving layer on the base material sheet in the simultaneous multilayer coating process, the surface tension and viscosity of the coating liquid of each layer are prepared, and the layers are uniformly mixed. It can be performed by a slide coating method in which a coating liquid for forming each layer with an appropriate thickness is slid and applied in a state where the layers are stacked one above the other.

  Here, the slide coating method is, for example, a method in which a plurality of coating liquids constituting each layer of the thermal transfer image-receiving sheet are applied to a base material sheet wound around a back roll in a state where they are stacked one above the other. 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. Further, since the coating liquid can be used up, waste is hardly generated, and since a high solid content coating liquid can be used, there is an advantage that the amount of solvent used can be reduced.

In the simultaneous multilayer coating step, as a mode of simultaneously coating a plurality of layers on the base sheet (A), (i) a porous layer (B), a receiving layer (C) on the base sheet (A), (Ii) Undercoat layer (D), porous layer (B), receptor layer (C) on substrate sheet (A), (iii) Porous layer (B) on primer sheet (A), primer Layer (E), Receptor layer (C), (iv) An undercoat layer (D), a porous layer (B), a primer layer (E) and a receptor layer (C) are simultaneously formed on the base sheet (A). The aspect to apply | coat can be mentioned.
In the simultaneous multilayer coating step, among the above-described embodiments, the undercoat layer (D), the porous layer (B), the primer layer (E), the receiving layer (C) on the (iv) substrate sheet (A). ) Are preferably applied simultaneously. According to such an embodiment, it is possible to obtain a thermal transfer image receiving sheet having excellent adhesion between layers and excellent printing sensitivity.

2. Next, the cooling process used in the present invention will be described. This step is a step of cooling a plurality of coating films formed on the substrate sheet (A) in the simultaneous multilayer coating step.
The method for cooling the plurality of coating films formed on the base sheet (A) in the cooling treatment step is not particularly limited as long as the coating film can be cooled to a desired temperature. As such a method, for example, the method of applying the coating film on the cooled base sheet (A), the surface of the roll that transports the base sheet (A) is cooled, and the base sheet ( A method of cooling the coating film via A), a method of spraying cold air on the coating film, a method of passing the substrate sheet on which the coating film is formed, through a cooling zone adjusted to room temperature below a desired temperature, etc. Can be mentioned. Especially in this process, it is preferable to use the method of apply | coating the said coating film on the base material sheet (A) cooled. According to such a method, since the coating film can be forcibly cooled immediately after the coating film is applied on the base sheet (A), a plurality of layers constituting the coating film are mixed. Can be prevented.

In the cooling treatment step, the temperature at which the coating film is cooled is not particularly limited as long as the viscosity of each layer constituting the coating film can be improved to such an extent that the layers do not mix with each other.
Moreover, the cooling temperature in the cooling process depends on the kind of the cooling gelling agent described above. Especially in this process, 0 to 30 degreeC is preferable, as for cooling temperature, 0 to 25 degreeC is more preferable, and also 3 to 20 degreeC is especially preferable.

3. Next, the drying process used in the present invention will be described. This step is a step of drying the plurality of coating films cooled in the cooling treatment step. In this step, the coating film is dried, so that these coating films are cured, and a receiving layer (C) having excellent releasability can be obtained.
In the drying step, the temperature for drying the coating film cooled in the cooling treatment step is preferably 30 ° C to 90 ° C, more preferably 40 ° C to 60 ° C. 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.
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.

[3] “Thermal transfer image receiving sheet” The thermal transfer image is superposed on the thermal transfer image receiving sheet of the present invention, and the thermal transfer sheet is heated by a thermal head to thermally transfer the sublimation dye from the thermal transfer sheet to the thermal transfer image receiving sheet. The styrene-acrylic copolymer (a) and the particulate resin filler (b) of the receiving layer (C) of the sheet are dyed and particles are not formed near the surface of the receiving layer (C). The resin filler (b) present in the form of a melt melts and smoothes the surface of the receiving layer (C). By utilizing such a phenomenon, the releasability of the thermal transfer image receiving sheet from the thermal transfer sheet is significantly improved during thermal transfer.

Hereinafter, the present invention will be specifically described with reference to examples. The indicated weight parts were described as solid content and diluted with pure water as necessary.
It describes below about sample preparation and evaluation methods, such as an image receiving sheet.

(1) Preparation of copolymer (a) and resin filler (b) The copolymers used in Examples 1 to 6 are emulsions 1 to 6, respectively, and the copolymers used in Comparative Examples 1 to 3 are Emulsions 7-9 were prepared by the following method.
(A) Preparation of copolymer (a) (styrene-acrylic copolymer) (i) Synthesis of emulsion 1 In a 500 mL Erlenmeyer flask, 103 g of styrene, 54 g of ethyl acrylate, 41 g of lauryl acrylate, 2 g of acrylic acid, emulsifier (No. 1.9 g of Ichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10) was added and stirred and mixed (hereinafter referred to as monomer A). In a 1 L three-necked flask, 200 g of distilled water was added and heated to 80 ° C., and about 20% of the total amount of monomer A was added and stirred for 10 minutes. Thereafter, 0.2 g of ammonium persulfate dissolved in 20 g of pure water was added and stirred for 10 minutes, and then the remaining 80% of the monomer A was dropped with a dropping funnel over 3 hours and further stirred for 3 hours. Thereafter, the mixture was cooled to room temperature and filtered through # 150 mesh (Japanese woven fabric) to obtain Emulsion 1 of Example. Molecular weight 242273, Tg 50 ° C. Further, from the molecular weight of styrene, ethyl acrylate and lauryl acrylate and the amount used for the reaction, the respective molar ratios are 58%, 32% and 10%.

(Ii) Synthesis of emulsions 2 to 9 Emulsions 2 to 9 were synthesized by performing a copolymerization reaction in the same manner as the emulsion 1 except that the copolymer-forming monomer blending ratio shown in Table 1 was used. The reaction time was continued until the presence of the monomer could not be confirmed by thin layer chromatography (TLC) or the amount of the monomer was not reduced.
(B) Resin filler (b)
In Examples 1 to 3, 5, 6 and Comparative Examples 2 and 3, a vinyl chloride-ethyl acrylate copolymer (manufactured by Nissin Chemical Industry Co., Ltd., trade name: VB900) comprising monomer units shown in Table 1 was used. used.
In Example 4, a vinyl chloride-ethyl acrylate copolymer (manufactured by Nissin Chemical Industry Co., Ltd., trade name: VB902) composed of monomer units shown in Table 1 was used.

(2) Physical property evaluation method of copolymer The molecular weight of the resin described in Table 1, the measurement of glass transition temperature, and the evaluation of releasability were those measured by the following methods, respectively.
(A) Molecular weight (Mn)
It is the number average molecular weight in terms of polystyrene measured by GPC (HLC-8020; manufactured by Tosoh Corporation, developing solvent; THF flow rate; 1.0 mL / min column; G2000HXL + G3000HXL + G5000HXL).
(B) Glass transition temperature (Tg)
Measurement was performed with a rigid pendulum type surface physical property tester (RPT3000W manufactured by A & D, temperature rising rate 3 ° C./min), and a point where a peak could be confirmed was defined as Tg.

(3) Evaluation of thermal transfer image receiving sheet The evaluation method of the produced thermal transfer image receiving sheet was based on the following method.
(I) Evaluation method of sticking and image kogation A black solid image was printed on the produced thermal transfer image-receiving sheet with a sublimation type thermal transfer printer (manufactured by ALTECH ADS, model: MEGAPIXELIII). And the presence of image defects such as peeling noise) were visually observed.
Koge is a color that turns brown as if burnt due to excessive heat applied to the print section. Further, the peeling trace appears when the ink ribbon layer and the receiving layer resin are fused with heat during printing and barely peeled off due to the winding force of the ink ribbon.
The criteria for sensory evaluation were as follows.
Evaluation standard for sticking ○: No peeling trace ×: Evaluation standard for image kogation where peeling trace exists ○: No image kogation ×: Image kogation exists

(B) Image density evaluation method The produced thermal transfer image-receiving sheet was subjected to an 18-gradation gradation image with an RGB value of 15 * n (n = 0 to 17) using a sublimation thermal transfer printer (manufactured by ALTECH ADS, model: MEGAIXELIII). Print and measure the density of the gradation corresponding to the values obtained by substituting 12 and 17 for n in the formula “15 * n” indicating the RGB value, using an optical densitometer (spectrolino, manufactured by Gretag Macbeth). The image densities are shown as 11 gradations and 18 gradations. However, a gradation with a higher RGB value corresponds to a condition that an image with a higher density can be obtained.

(C) Light resistance evaluation method The light resistance of the printed matter obtained under the above printing conditions was evaluated using a xenon fade meter under the following conditions.
(I) Conditions for light resistance evaluation / irradiation tester: Ci4000 manufactured by Atlas
・ Light source: Xenon lamp ・ Filter: Inside = CIRA
Outside = soda lime black panel temperature: 45 (° C)
・ Irradiation intensity: measured value at 1.2 (W / m ² ) −420 (nm) ・ Irradiation energy: integrated value at 300 (kJ / m ² ) −420 (nm)

(Ii) Light resistance evaluation Next, the change in optical reflection density before and after irradiation under the above light resistance conditions was measured with an optical densitometer (Spectrolino, manufactured by Gretag Macbeth), and the optical reflection density before irradiation was around 1.0. With respect to these steps, L ^* , a ^* , and b ^* were calculated, and the hue change (ΔE) was calculated using the following hue change equation.
(Hue change formula)
△ a = after storage ^{a *} - before saving ^{a *}
△ b = after storage ^{b *} - before storage ^{b *}
When
ΔE = square root of (square of Δa + square of Δb)

[Example 1]
A thermal transfer image receiving sheet was produced by the following method, and the produced thermal transfer image receiving sheet was evaluated.
(1) Preparation of thermal transfer image-receiving sheet 1 RC paper (STF-150, manufactured by Mitsubishi Paper Industries Co., Ltd.) was used as a base sheet, and a porous layer forming coating solution 1 and a receiving layer forming coating solution 1 having the following compositions were used. Heat to ℃, apply using slide coating so that the thickness when dried is 30μm and 5μm, respectively, cool and gel at 5 ℃ for 1 minute, dry at 50 ℃ for 5 minutes, thermal transfer An image receiving sheet 1 was obtained.

(I) Porous layer forming coating solution 1
・ Hollow particles (Rohm and Haas, trade name: HP-91) (as solids) 70 parts by weight Gelatin (Nitta Gelatin Co., Ltd., trade name: RR) (as solids) 30 parts by weight Surfactant (manufactured by Nissin Chemical Industry Co., Ltd., trade name: Surfinol 440) 0.15 parts by weight

(Ii) Receiving layer forming coating solution 1
Emulsion 1 (as solids) 70 parts by weight Resin filler (VB900) (as solids) 15 parts by weight Gelatin (made by Nitta Gelatin Co., Ltd., trade name: RR) (as solids) 15 parts by weight Silicone mold release agent (Shin-Etsu Chemical Co., Ltd., trade name: KF615A) 10 parts by weight Surfactant (Nissin Chemical Industry Co., Ltd., trade name: Surfynol 440) 1 part by weight

(2) Evaluation of Thermal Transfer Image Receiving Sheet 1 The thermal transfer image receiving sheet prepared above was subjected to (i) sticking and image burnt evaluation, (ii) image density evaluation, and (iii) light resistance evaluation. The evaluation results are summarized in Table 1.
An electron micrograph (scanning electron micrograph) of the surface of the receiving layer of the obtained thermal transfer image-receiving sheet 1 is shown in FIG. In FIG. 1, it is observed that the copolymer (a) corresponding to the resin filler (b) of the present invention is present in the form of particles without forming a film on the surface of the thermal transfer image-receiving sheet 1.
(3) Evaluation by thermal transfer of the thermal transfer image receiving sheet 1 The thermal transfer sheet was superposed on the thermal transfer image receiving sheet 1, and the thermal transfer sheet was heated by a thermal head to thermally transfer the sublimation dye from the thermal transfer sheet to the thermal transfer image receiving sheet.
It was observed that the surface of the receiving layer (C) was smoothed by melting the resin filler (b) present in the vicinity of the receiving layer surface of the thermal transfer image-receiving sheet 1 during thermal transfer.
An electron micrograph before transfer of the thermal transfer image-receiving sheet 1 is shown in FIG. 1, and an electron micrograph after transfer is shown in FIG.

[Examples 2 to 6]
A thermal transfer image receiving sheet was produced by the following method, and the produced thermal transfer image receiving sheet was evaluated.
(1) Production of Thermal Transfer Image Receiving Sheets 2-6 Copolymers obtained from Emulsions 2-6 instead of Emulsion 1 used in Receptive Layer Forming Coating Liquid 1 of Example 1 in Examples 2-6 Receiving layer forming coating solutions 2 to 6 were prepared using (a) and the resin filler (b), respectively.
Next, a thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer forming coating solutions 2 to 6 were used in Examples 2 to 6 instead of the receiving layer forming coating solution 1 of Example 1. 2-6 were produced.
(2) Evaluation of Thermal Transfer Image Receiving Sheets 2 to 6 The thermal transfer image receiving sheets 2 to 5 were evaluated in the same manner as the thermal transfer image receiving sheet 1 in Example 1. The evaluation results are summarized in Table 1.

[Comparative Examples 1-3]
A thermal transfer image receiving sheet was produced by the following method, and the produced thermal transfer image receiving sheet was evaluated.
(1) Production of Thermal Transfer Image Receiving Sheets 7 to 9 Table 1 in Comparative Example 1 shows in place of the copolymer (a) and resin filler (b) used in the receiving layer forming coating solution 1 of Example 1. Copolymer (a), resin filler (b) shown in Table 1 in Comparative Example 2, and copolymer (a) and resin filler (b) shown in Table 1 in Comparative Example 3 are used for forming a receiving layer. Coating liquids 7 to 9 were prepared.
Next, a thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the receiving layer forming coating solutions 7 to 9 were used in Comparative Examples 1 to 3 instead of the receiving layer forming coating solution 1 of Example 1. 7-9 were produced.
(2) Evaluation of Thermal Transfer Image Receiving Sheets 7-9 The thermal transfer image receiving sheets 7-9 were evaluated in the same manner as in Example 1 for the thermal transfer image receiving sheet 1. The evaluation results are summarized in Table 1.
3 and 4 show electron micrographs (scanning electron micrographs) of the receiving layer surfaces of the thermal transfer image-receiving sheets 7 and 8 obtained in Comparative Examples 1 and 2, respectively.

2 is an electron micrograph (scanning electron micrograph) of the surface of the receiving layer before transfer of the thermal transfer image-receiving sheet 1 obtained in Example 1. FIG. 2 is an electron micrograph (scanning electron micrograph) of the receiving layer surface after transfer of the thermal transfer image-receiving sheet 1 obtained in Example 1. FIG. 4 is an electron micrograph (scanning electron micrograph) of the surface of the receiving layer of the thermal transfer image-receiving sheet 7 obtained in Comparative Example 1. FIG. 6 is an electron micrograph (scanning electron micrograph) of the surface of the receiving layer of the thermal transfer image-receiving sheet 8 obtained in Comparative Example 2. FIG.

Claims (6)

A thermal transfer image receiving sheet in which a porous layer (B) containing at least hollow particles on a substrate sheet (A) and a receiving layer (C) for receiving a heat transferable dye from a thermal transfer sheet upon heating are formed on the porous layer (B). There,
The receptor layer (C) contains at least a dye-stainable styrene-acrylic copolymer (a) and a resin filler (b), a cooling gelling agent (c), and a release agent (d). And
The weight ratio [(a) / (b)] of the styrene-acrylic copolymer (a) and the resin filler (b) contained in the receiving layer (C) is 70 to 90/30 to 10,
The number average molecular weight (polystyrene conversion) of the styrene-acrylic copolymer (a) is 150,000 or more,
The resin filler (b) has a glass transition temperature (Tgb) higher than the glass transition temperature (Tga) of the styrene-acrylic copolymer (a), and forms a film in the receiving layer (C) before the thermal transfer. A thermal transfer image-receiving sheet characterized by being present in the form of particles. The thermal transfer image-receiving sheet according to claim 1, wherein the styrene unit in the styrene-acrylic copolymer (a) forming the receiving layer (C) is 50 to 70 mol%. The resin filler (b) forming the receptor layer (C) is a vinyl chloride-acrylic copolymer, the vinyl chloride unit in the copolymer is 75 to 95 mol%, and the glass transition temperature (Tgb) The thermal transfer image receiving sheet according to claim 1 or 2, wherein the temperature is 60 to 100 ° C. The thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein the cooling gelling agent (c) forming the receiving layer (C) is gelatin. The receiving layer (C) is at least 50 to 95% by weight of a styrene-acrylic copolymer (a) and a resin filler (b), 2 to 30% by weight of a cooling gelling agent (c) , and a release agent (d) 2 The thermal transfer image-receiving sheet according to any one of claims 1 to 4, wherein the thermal transfer image-receiving sheet is contained in an amount of -30% by weight. Wherein the porous layer (B) is contained at least hollow particles (e) and cooling a gelling agent (f), a thermal transfer image-receiving sheet according to any one of claims 1 to 5.