JP2008055889A - Coating liquid for receiving layer formation, receiving layer of thermal transfer image receiving sheet, and thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a thermal transfer image receiving sheet which can not only maintain the picture quality but also can control change of coating liquid consistency with time on the receiving layer and the change of the image receiving sheet with time before printing and can obtain the superb quality images. <P>SOLUTION: The invention offers the thermal transfer image receiving sheet 10 which has the base material 11, and a receiving layer 12 formed on the base materal and containing an acetal resin with the specific structure, coloring matter of thermal diffusion property and metal ion content compound which can be chelated. The consistency of the coating liquid forming the receiving layer has a viscosity in second measured by a Zahn cup (Rigo Co., Ltd., No.4) of less than 10 seconds in both conditions when the coating liquid is adjusted and produced and after 30 minutes stirring from the time of production. Also, it is preferable that glass transition temperature of the acetal resin is 85°C or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet used for recording by a sublimation thermal transfer system, a receiving layer forming coating solution, and a receiving layer of a thermal transfer image receiving sheet obtained using the receiving layer forming coating solution. Relates to a thermal transfer image-receiving sheet that is excellent in printing density even at high-speed printing and that can obtain a thermal transfer printed matter having high durability such as light resistance.

  Conventionally, a thermal transfer method is widely known as a method for easily forming a high-definition image. Various thermal transfer methods are known. Among them, a sublimation dye is used as a recording material, and this is supported on a base sheet such as paper or plastic film to form a thermal transfer sheet. A sublimation transfer method for forming various full-color images by dyeing the sublimation dye on a thermal transfer image-receiving sheet having a dye-receiving layer on the surface thereof is known as a method capable of forming a higher-definition image. Since this sublimation transfer method uses a sublimation dye as a color material, it has the advantage that the density gradation can be freely adjusted and a full color image of an original can be expressed. In addition, the image formed with the dye is very clear and excellent in transparency, so it is excellent in intermediate color reproducibility and gradation reproducibility, and can form high-quality images comparable to silver salt photographs. It has the advantage of being possible. Because of these advantages, the sublimation transfer method has now been widely used in digital camera photographic printers and the like.

  By the way, in such thermal transfer recording, the sublimation dye used for the thermal transfer sheet is important, and the conventional one has a defect that the stability of the obtained image, that is, light resistance and fixing property are not good. ing. Therefore, in order to improve these points, for example, each of the publications of Patent Documents 1 to 3 uses a chelatable heat diffusible dye and is chelated on a thermal transfer image-receiving sheet containing a metal ion-containing compound. An image forming method for forming an image with a dye (hereinafter referred to as chelate dye) is disclosed. According to this image forming method, an image having a high image density and a certain improvement effect on the dye fixing property can be obtained.

  However, the diffusion and chelation of the dye transferred from the thermal transfer sheet to the thermal transfer thermal transfer image-receiving sheet does not proceed sufficiently with only the energy at the time of thermal transfer, so the uniformity of the color reproducibility of the transferred image and the fixability by the unreacted dye I was still worried. Further, since unreacted dye is present near the surface after printing, the durability of the transferred image is not sufficient, and it is difficult to maintain the image quality during image formation.

  In order to improve the above problems, in the conventional image forming method using a chelate dye, after forming an image, heat treatment is performed again, or a protective layer is provided on the image to impart durability. Technology is known. For example, in each publication of Patent Documents 4 to 6, by transferring a metal ion-containing compound onto an image formed on a thermal transfer image-receiving sheet, the reaction efficiency of the chelate dye and the metal ion is increased, and the color of the unreacted dye is changed. It is disclosed to prevent turbidity and deterioration of durability. Further, Japanese Patent Application Laid-Open No. 2005-228561 discloses that light resistance can be improved by transferring an ultraviolet absorber after image formation.

  However, the metal ion has a property of reacting with water, and the metal ion reacted with water has a low reaction efficiency with the chelate dye. For this reason, when the image receiving sheet is left under high temperature and humidity before image formation, there is a problem in that the reaction efficiency between the chelate dye and the metal ion is lowered, and the image density is lowered during image formation.

JP 59-78893 A JP 59-109394 A Japanese Unexamined Patent Publication No. 60-2398 JP-A-5-42774 Japanese Patent Laid-Open No. 9-188073 JP-A-11-208129 JP-A-10-226179

  The present invention has been made in view of the above-mentioned problems, not only is it possible to maintain stability and image quality against changes over time during coating of the receiving layer, but also prevents changes over time of the image receiving sheet before printing, An object of the present invention is to provide a thermal transfer image receiving sheet capable of obtaining an image of excellent quality.

  In order to solve the above problems, the present invention provides a coating liquid for forming a receiving layer provided on a substrate of a thermal transfer image-receiving sheet, a metal ion capable of chelating with an acetal resin and a heat-diffusible dye. Viscosity measured with Zahn cup (Ransha Co., No. 4) containing the compound contained and the viscosity of the coating liquid was adjusted by preparing the coating liquid and after stirring for 30 minutes from the time of preparation. It provides that the number of seconds is both 10 seconds or less. The present invention also provides a receiving layer of a thermal transfer image-receiving sheet provided on a substrate, that is, a receiving layer coating, using the receiving layer forming coating liquid described above. The present invention also relates to a thermal transfer image-receiving sheet having a base material and a receiving layer formed on the base material and containing an acetal resin, and capable of chelating with a thermally diffusible dye in the receiving layer. In the coating liquid containing the metal ion-containing compound and forming the receptor layer, the viscosity of the coating liquid is adjusted by preparing the coating liquid and after stirring for 30 minutes from the time of preparation. Under the conditions, the thermal transfer image-receiving sheet is provided in which both the viscosity seconds measured by Zahn cup (Kohsha, No. 4) are 10 seconds or less. The acetal resin is preferably a compound represented by the specified formula. Moreover, it is preferable that the glass transition temperature of the acetal resin is 85 ° C. or higher.

上記式中Ｒは、置換基を有してもよい炭化水素を表し、ｌ、ｍ、ｎは各構造単位のｍｏｌ％を表し、７１≦ｌ≦８０、０≦ｍ≦３、２２≦ｎ≦２７の範囲である。 According to the present invention, with respect to the thermal transfer image-receiving sheet in which the receiving layer contains an acetal resin and a metal ion compound capable of chelating with a heat diffusible dye, the acetal resin has a glass transition temperature. Is a compound represented by the following formula having a number average molecular weight of 60000 or more and 100000 or less, not only being able to maintain image quality but also a change with time in viscosity during coating. Therefore, it is possible to obtain a thermal transfer image receiving sheet that can suppress the change with time of the image receiving sheet before printing and can obtain an image of excellent quality.

In the above formula, R represents a hydrocarbon which may have a substituent, l, m, and n represent mol% of each structural unit, 71 ≦ l ≦ 80, 0 ≦ m ≦ 3, 22 ≦ n ≦ 27 ranges.

  The thermal transfer image-receiving sheet of the present invention can not only maintain the image quality after image formation, but also prevent the image-receiving sheet before printing from changing with time, and further, the receiving layer provided on the substrate of the thermal transfer image-receiving sheet In the coating liquid for forming a film, an effect of suppressing a change with time in viscosity at the time of coating is exhibited.

  Hereinafter, the thermal transfer image receiving sheet of the present invention will be described in detail.

  In the thermal transfer image-receiving sheet of the present invention, the acetal resin is represented by the following formula with respect to the thermal transfer image-receiving sheet in which the receptor layer contains an acetal resin and a metal ion compound capable of chelating with a dye. It is a compound characterized by the above-mentioned.

上記式中Ｒは、置換基を有してもよい炭化水素を表し、ｌ、ｍ、ｎは各構造単位のｍｏｌ％を表し、７１≦ｌ≦８０、０≦ｍ≦３、２２≦ｎ≦２７の範囲である。

In the above formula, R represents a hydrocarbon which may have a substituent, l, m, and n represent mol% of each structural unit, 71 ≦ l ≦ 80, 0 ≦ m ≦ 3, 22 ≦ n ≦ 27 ranges.

  Next, the thermal transfer image receiving sheet of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a thermal transfer recording material comprising a thermal transfer image receiving sheet of the present invention and a thermal transfer sheet used in combination with the thermal transfer image receiving sheet. As illustrated in FIG. 1, in the thermal transfer recording material 1, a thermal transfer image receiving sheet 10 is formed on a base 11, an acetal resin having a specific structure formed on the base 11, and a thermal diffusible dye. And a receiving layer 12 containing a metal ion compound capable of chelating reaction, and the thermal transfer sheet 20 is formed on the base sheet 21 and the base sheet 21, and is formed of a binder resin and thermal diffusivity. It consists of the dye layer 22 containing a pigment | dye.

  FIG. 2 is a schematic view showing another example of a thermal transfer recording material constituted by a set of the thermal transfer image receiving sheet of the present invention and a thermal transfer sheet used in combination with the thermal transfer image receiving sheet. As illustrated in FIG. 2, the thermal transfer recording material 2 has a receiving layer 12 formed on a substrate 11, and a back surface of the substrate 11 opposite to the surface on which the receiving layer 12 is formed. The dye transfer layer 22 is formed on the thermal transfer image-receiving sheet 10 ′ having the configuration in which the layer 13 is formed and the base sheet 21, and the surface of the base sheet 21 opposite to the surface on which the dye layer 22 is formed. It may be composed of a thermal transfer sheet 20 ′ having a structure in which a heat-resistant slip layer 23 is formed on the surface.

  Hereinafter, the thermal transfer image receiving sheet of the present invention will be described in detail.

(1) Receiving Layer First, the receiving layer constituting the thermal transfer image receiving sheet used in the present invention will be described. The receptor layer in the present invention contains an acetal resin and a metal ion compound capable of chelating with a dye.

  In general, when an acetal resin is applied alone as a coating solution for forming a receiving layer, a change with time occurs with respect to viscosity due to the influence of hydrogen bonding between the acetal resins, which causes a problem in coating. For example, by using an acetal resin and a coating solution for forming a receiving layer containing a metal ion-containing compound, the change over time during coating of the receiving layer can be suppressed for unknown reasons.

i. Acetal resin The acetal resin used in the present invention is a compound represented by the following formula. The acetal resin used in the present invention is not limited to a production method, but usually an acetal resin obtained by acetalizing polyvinyl alcohol with an aldehyde compound is used.

上記式中Ｒは、置換基を有してもよい炭化水素を表し、ｌ、ｍ、ｎは各構造単位のｍｏｌ％を表し、７１≦ｌ≦８０、０≦ｍ≦３、２２≦ｎ≦２７の範囲である。

In the above formula, R represents a hydrocarbon which may have a substituent, l, m, and n represent mol% of each structural unit, 71 ≦ l ≦ 80, 0 ≦ m ≦ 3, 22 ≦ n ≦ 27 ranges.

  Specific examples of R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a phenyl group, a benzyl group, and a naphthol group. In particular, in the present invention, it is preferable to use a methyl group, an ethyl group, or a propyl group as R.

  As the aldehyde compound used for the acetalization, those capable of obtaining an acetal resin having a desired acetal group can be arbitrarily selected and used. Examples of the aldehyde compound used in the present invention include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexylaldehyde, 2-ethylhexylaldehyde, benzaldehyde, 1-naphthaldehyde, o-tolualdehyde, p-tolualdehyde, p- Examples thereof include ethylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, and 3-phenylchloropionaldehyde.

  When acetal resin is obtained by acetalizing polyvinyl alcohol with the above aldehyde compound, it is usually difficult to completely acetalize because the acetyl group or hydroxyl group partially remains irreversibly, but the obtained acetal type The degree of acetalization of the resin is preferably such that the mol% of the acetal part is greater than 71% with respect to the entire resin. When the degree of acetalization is lower than the above range, when the image receiving sheet is left under high temperature and high humidity, the reaction efficiency between the chelate dye and the metal ion is lowered, and the image density is lowered during image formation. Moreover, the acetalization degree of the obtained acetal resin will not be able to take the structure of the acetal resin when the mol% of the acetal part is 80 or more with respect to the whole resin. In addition, the value measured by the infrared spectroscopy (IR) shall be used for the acetalization degree of the said acetal type resin in this invention.

The number average molecular weight of the acetal resin used in the present invention is within a range in which the above-described dye layer of the thermal transfer sheet and the receptor layer are not fused when the thermal transfer image-receiving sheet is formed using the thermal transfer image-receiving sheet of the present invention. If it is in, it will not be limited to profit. Among them, the number average molecular weight of the acetal resin used in the present invention is preferably 60000 or more, and particularly preferably in the range of 60000 to 100,000.
If the number average molecular weight of the acetal resin is higher than the above range, the viscosity of the solution becomes high when the acetal resin is dissolved in a solvent, and it becomes difficult to form a receiving layer having excellent flatness, for example. Because there are cases. Further, if the number average molecular weight is smaller than the above range, the dye layer and the receiving layer may be heat-sealed (deterioration of releasability at the time of printing). This is because the back surface of the image receiving paper and the receiving layer are blocked, and the preservability before printing is adversely affected. The storage stability before printing is an evaluation for examining whether the change in hue and density is observed after the thermal transfer image-receiving sheet before printing is stored in a high-temperature and high-humidity environment as compared with that before storage.
Here, the value measured by gel permeation chromatography (GPC) shall be used for the number average molecular weight of the acetal resin in the present invention.

  Only one kind of acetal resin used in the present invention may be used, or two or more kinds may be used in combination. In the present invention, as an embodiment in which two or more kinds of the acetal resins are mixed and used, for example, for the purpose of adjusting viscosity, improving printability, etc., polyvinyl alcohols having different number average molecular weights are used, and the acetalization reaction is performed separately Examples of using a mixture of the resins obtained by performing the above and modes using a mixture of polyvinyl alcohols having different number average molecular weights and acetalization reaction can be exemplified.

ii. Metal ion In addition to the acetal resin, the receptor layer contains a metal ion-containing compound capable of fixing the transferred dye. A preferable addition amount of the metal ion-containing compound to the receptor layer is not particularly limited because it increases or decreases depending on the amount of the dye transferred from the thermal transfer sheet, but is preferably 50% by mass or less with respect to the total fixed amount of the receptor layer. 40 mass% or less is preferable. When the metal ion-containing compound is introduced in an amount of 50% by mass or more, the adhesion between the receiving layer and the substrate decreases, and when the thermal transfer image receiving sheet is wound, the back surface of the thermal transfer image receiving sheet and the receiving layer may be blocked. Because there is.

As a metal ion containing compound, the compound represented, for example by a following formula is mentioned.

In the above formula, M ²⁺ represents a divalent metal ion. X represents a coordination compound capable of forming a complex by coordination with the metal ion M ²⁺ , and m represents 2 or 4. The plurality of coordination compounds X may be the same as or different from each other. Y ⁻ represents a counter ion of the metal ion M ²⁺ , and n represents an integer of 0, 1, or 2. Further, the compound represented by the above formula may have a neutral ligand depending on the central metal, and typical ligands include H ₂ O, NH ₃ , pyridine, N-methylimidazole, etc. Is mentioned.

In the compound represented by the above formula, M ²⁺ represents a divalent metal ion. Examples of the metal ion include Mg ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ and Fe ^{2. +} Etc. can be mentioned. Among these, Co ²⁺ and Ni ²⁺ are particularly preferable. In the compound represented by the above formula, Y ⁻ represents a counter anion of the metal ion M ²⁺ , and this counter anion is an organic or inorganic anion. In particular, the metal ion M ²⁺ and the coordination compound (X) A compound that makes the complex formed by n soluble in an organic solvent such as methyl ethyl ketone and tetrahydrofuran (THF) is preferable. Specific examples of the counter anion include organic salts such as alkyl carboxylic acid, aryl carboxylic acid, alkyl sulfonic acid, aryl sulfonic acid, alkyl phosphoric acid, aryl phosphoric acid and aryl boric acid.

iii. Other compounds The receiving layer may contain other compounds in addition to the acetal resin and the metal ion-containing compound. As another compound used for the said receiving layer, a mold release agent can be mentioned, for example. Since a release agent is contained in the receiving layer, it is possible to prevent fusion with the dye layer or a decrease in printing sensitivity during thermal transfer. Therefore, in the present invention, the release agent is used as the other compound. Is preferably used.

Examples of the release agent include conventionally known release agents such as solid waxes such as polyethylene wax, amide wax, and Teflon (registered trademark), fluorine-based and phosphate-based surfactants, silicone, and the like. Can also be used. A particularly preferred release agent is a modified silicone, specifically,
1) Modified silicone oil side chain type,
2) Modified silicone oil both ends type,
3) Modified silicone oil one end type,
4) Modified silicone oil side chain both ends type,
5) Silicone graft acrylic resin, and 6) methylphenyl silicone oil.

The modified silicone oil is classified into a reactive silicone oil and a non-reactive silicone oil. Examples of the reactive silicone oil include amino modification, epoxy modification, carboxyl modification, carbinol modification, methacryl modification, mercapto modification, phenol modification, one-terminal reactivity, and heterofunctional 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, fluorine modification and the like.
Among the above silicone oils, reactive silicone oils of a type having a group that is reactive with the film-forming component may react with and bind to the hydroxyl group of the residue in the acetal resin, and appropriately use a curing agent, a catalyst, or the like. It is also possible to add and use.

  In the present invention, only one type of release agent may be used, or two or more types may be mixed and used.

  The amount of the release agent added is preferably in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the resin component contained in the receiving layer. This is because if the added amount of the release agent is larger than the above range, the printing sensitivity may be lowered. Moreover, it is because there exists a possibility that the dye layer of a thermal transfer sheet and the said receiving layer may be heat-seal | fused when there is less addition amount than the said range.

  In the receiving layer in the present invention, a curing agent or a catalyst can be used as the other compound in addition to the release agent. In addition, pigments and fillers such as titanium oxide, zinc oxide, kaolin, clay, calcium carbonate, and fine powder silica can be used for the purpose of improving the whiteness of the receiving layer and further enhancing the sharpness of the transferred image. Furthermore, plasticizers, ultraviolet absorbers, light stabilizers, antioxidants, fluorescent brighteners, antistatic agents, and the like can also be used.

(2) Substrate Next, the substrate constituting the thermal transfer image receiving sheet used in the present invention will be described. The base material in this invention has a function which supports the said receiving layer.

  The material constituting the substrate used in the present invention is not particularly limited as long as it has mechanical characteristics that can withstand heat applied during image formation and has no trouble in handling. Examples of such materials include polyester, polyarylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene / vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, and polyvinylidene chloride. , Polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene / perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoropropylene, polychloro A plastic film or sheet made of a resin material such as trifluoroethylene or polyvinylidene fluoride It is possible to have.

  In addition, as the base material used in the present invention, the above-mentioned plastic film or sheet, the white film formed by adding a white pigment or filler to the resin material, or the sheet having a microvoid inside the base material, etc. Condenser paper, glassine paper, sulfuric acid paper, synthetic paper (polyolefin, polystyrene), fine paper, art paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper Cellulose fiber paper or the like can be used.

  As a structure of the base material used for this invention, the structure which consists of a single layer may be sufficient, or it may have the structure by which the several layer was laminated | stacked. Examples of the configuration in which a plurality of layers are stacked include a configuration in which cellulose fiber paper and synthetic paper are stacked, and a configuration in which cellulose fiber paper and a plastic film are stacked. Further, at least one surface may be subjected to an adhesion treatment.

  The thickness of the substrate used in the present invention is not particularly limited as long as the desired self-supporting property is obtained in accordance with the material constituting the substrate, but is usually preferably in the range of 3 μm to 300 μm, In particular, the range of 100 μm to 250 μm is preferable.

(3) Thermal transfer image-receiving sheet The thermal transfer image-receiving sheet used in the present invention may have other configurations in addition to the receiving layer and the substrate. As such other configurations. For example, on the surface opposite to the surface on which the receiving layer of the substrate is provided, a back layer formed for the purpose of improving the transportability of the thermal transfer image-receiving sheet and preventing curling, or between the receiving layer and the substrate. An intermediate layer formed for the purpose of imparting a predetermined function can be exemplified.

  The material constituting the back layer is not particularly limited as long as it is a material that can impart a desired function to the back layer, but a material obtained by adding a filler to a resin material is usually used.

  Examples of the resin material constituting the back layer include acrylic resins, cellulose resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl alcohol resins, polyamide resins, polystyrene resins, polyester resins, halogenated polymers, and the like. Can do. Moreover, what hardened | cured such a resin material with hardening | curing agents, such as an isocyanate compound, can also be used.

  Examples of the filler contained in the back layer include, for example, acrylic fillers, polyamide fillers, fluorine fillers, organic fillers such as polyethylene wax, amino acid powders, and inorganic fillers such as silicon dioxide and metal oxides. Can be mentioned.

  Examples of the intermediate layer include an antistatic layer, a cushion layer, an intermediate layer to which a white pigment and a fluorescent whitening agent are added, an easily adhesive layer, and the like.

  In the present invention, an antistatic layer, a writing layer or the like may be formed instead of the back layer.

(4) Manufacturing Method of Thermal Transfer Image Receiving Sheet Next, a manufacturing method of the thermal transfer image receiving sheet used in the present invention will be described. The method for producing the thermal transfer image-receiving sheet used in the present invention is not particularly limited as long as it is a method capable of producing the thermal transfer image-receiving sheet having the above-described configuration. Usually, the binder resin, the metal ion-containing compound, and the release agent are used. An additive and, if necessary, additives are optionally added, and after sufficiently kneading with a solvent, a diluent, etc. to prepare a coating solution for forming a receiving layer, this is applied on the base material. For example, a method of producing a receptor layer by applying and drying by a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, or the like is used.

  The above receiving layer forming coating solution is a coating solution for forming a receiving layer provided on the substrate of the thermal transfer image receiving sheet, and is a metal capable of chelating with an acetal resin and a heat diffusible dye. It contains an ion-containing compound, and other additives such as the above mold release agent and, if necessary, additives, etc., and is kneaded and adjusted sufficiently with a solvent, diluent, etc. When the viscosity of the working liquid was prepared by adjusting the coating liquid (immediately after preparation) and after stirring for 30 minutes from the time of preparation, the viscosity seconds measured by Zahn cup (Ranshasha, No. 4) Both have the characteristic of being 10 seconds or less.

The coating amount of the receptor layer forming coating solution is preferably 0.5g / m ² ~4.0g / m ² in dry. This is because if the coating amount is less than the above range, unevenness occurs in fixing the dye and the dye acceptability may be lowered. Moreover, it is because productivity etc. may fall when there are more coating amounts than the said range.

  Next, each configuration of the thermal transfer sheet used in combination with the thermal transfer image receiving sheet of the present invention will be described in detail.

(Base material)
The base material used for the thermal transfer sheet will be described. The substrate used for the thermal transfer sheet is not particularly limited as long as it can form a dye layer and has predetermined heat resistance and strength. Examples of such a substrate include, for example, a polyethylene terephthalate film, a 1,4-polycyclohexylenedimethylene terephthalate film, a polyethylene naphthalate film, and a polyphenylene sulfide having a thickness of about 0.5 to 50 μm, preferably about 1 to 10 μm. Film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film, etc. are used. .

(Dye layer)
The thermal transfer sheet used for forming an image on the receiving layer of the thermal transfer image-receiving sheet has a structure in which a dye layer is provided on a substrate. In the present invention, the dye layer is a chelating heat-diffusible dye. Containing a binder resin and the heat diffusible dye as main components. First, the binder resin of the dye layer is not particularly limited as long as the dye is not easily diffused by heat and does not cause problems such as bleeding of the dye during storage or thermal fusion with the image receiving sheet during thermal transfer. Not known, but known ones can be used. Specifically, acrylic resins and derivatives thereof, polystyrene, polycarbonate, polysulfone, polyethersulfone, polyimide, polyvinyl acetal, polyvinyl butyral, polyester resin, polyurethane resin, vinyl chloride vinyl acetate copolymer resin, nitrocellulose, ethyl cellulose, acetic acid Examples thereof include cellulose such as cellulose and derivatives thereof.

  The heat diffusible dye is not particularly limited as long as it can chelate with the metal ion-containing compound contained in the receiving layer of the thermal transfer image-receiving sheet. General yellow dye, magenta dye, cyan dye Etc. can be used. Especially, it is preferable that it is a heat diffusible dye represented by the following general formula (3)-(8), (10), (11).

  (A) Thermally diffusible dye represented by the general formula (3)

(Wherein R ₁₁ represents a substituent, R ₁₂ represents an alkyl group, an alkenyl group, an alkynyl group or a cycloalkyl group, R ₁₃ and R ₁₄ represent a hydrogen atom or a substituent, and R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ represent a hydrogen atom, an alkyl group, or an aryl group, and Z ₁₁ represents a nonmetallic atom group necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring.

The substituent represented by R ₁₁ is not particularly limited, and examples thereof include alkyl groups, cycloalkyl groups, aryl groups, acylamino groups, alkylthio groups, arylthio groups, alkenyl groups, halogen atoms, alkynyl groups, and heterocyclic groups. Arylsulfonyl group, alkylsulfinyl group, arylsulfinyl group, phosphono group, acyl group, carbamoyl group, sulfamoyl group, sulfonamido group, cyano group, alkoxy group, aryloxy group, heterocyclic oxy group, siloxy group, acyloxy group, Sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group, anilino group, imide group, ureido group, alkoxycarbonylamino group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic thio group, thioureido group, carboxyl group ,carboxylic acid Salt, a hydroxyl group, a mercapto group, and each group and a nitro group.

  These substituents may be further substituted with the same substituent.

The alkyl group, alkenyl group, alkynyl group or cycloalkyl group represented by R ₁₂ may be substituted with the same substituent as the substituent represented by R ₁₁ .

In the general formula (3), R ₁₃ and R ₁₄ represents a hydrogen atom or a substituent. Examples of the substituent represented by R ₁₃ and R ₁₄ include the same groups as the substituent represented by R ₁₁ , and these substituents may be further substituted with the same substituent.

In the general formula (3), R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ represent a hydrogen atom, an alkyl group or an aryl group. Examples of the alkyl group and aryl group represented by R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ include the same groups as the alkyl group and aryl group in R ₁₁ .

The alkyl group and aryl group represented by R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ may be substituted with the same substituent as the substituent represented by R ₁₁ .

In the general formula (3), Z ₁₁ represents a nonmetallic atom group necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring.

Specific examples of such a heterocyclic ring include pyridine ring, pyrazole ring, imidazole ring, pyrazine ring, pyrimidine ring, triazine ring, thiazole ring, oxazole ring, quinoline ring, benzothiazole ring, benzoxazole ring and the like. be able to. These rings may have a substituent, and examples of the substituent include the same groups as the substituent represented by R ₁₁ .

  (B) Thermally diffusible dye represented by the general formula (4)

(Wherein R ₂₁ represents a trifluoromethyl group, an alkyl group, an aryl group, an alkoxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carbamoyl group, an amino group, or a cyano group, and R ₂₂ represents represents an alkyl group, an acyl group, a carbamoyl group, an alkoxycarbonyl group, R ₂₃ represents an alkyl group, an alkenyl group, an aryl group. However, the total number of carbon atoms contained in R ₂₁ and R ₂₂ is 3 or more .X ₂₁ Represents —CR ₂₄ R ₂₅ —, —S—, —O—, —NR ₂₆ —, wherein R ₂₄ and R _{25 each} represent a hydrogen atom, a halogen atom or a substituent, and R ₂₆ represents a hydrogen atom or a substituted group. Y ₂₁ represents a group of atoms necessary to form a 5- to 6-membered ring.
Since the substituent is the same as the substituent in the general formula (I) described above, description thereof is omitted here.

In the general formula (4), R ₂₁ represents a trifluoromethyl group, an alkyl group, an aryl group, an alkoxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carbamoyl group, an amino group, or a cyano group.
R ₂₁ is preferably an alkyl group, a trifluoromethyl group, an alkoxycarbonyl group, an acyl group, a carbamoyl group, or a cyano group, and more preferably an alkyl group.

R ₂₂ represents an alkyl group, an acyl group, a carbamoyl group, or an alkoxycarbonyl group.

R ₂₃ represents an alkyl group, an alkenyl group, or an aryl group.

X ₂₁ represents —CR ₂₄ R ₂₅ —, —S—, —O—, —NR ₂₆ —, and preferably —CR ₂₄ R ₂₅ —, —S—, —O—.

R ₂₄ and R ₂₅ represent a hydrogen atom, a halogen atom, or a substituent.
Since the substituent is the same as the substituent in the general formula (I) described above, description thereof is omitted here.

  As the substituent, a hydrogen atom, an alkyl group, and an aryl group are preferable.

R ₂₆ represents a hydrogen atom or a substituent.
Examples of the substituent include the same substituents as those exemplified as R ₂₄ and R ₂₅ .

Y ₂₁ represents an atomic group necessary for forming a 5- to 6-membered ring. Preferably, it is an atomic group necessary for forming a 6-membered ring. For example, a cyclopentane ring, a cyclohexane ring, a benzene ring, a pyridine ring, a naphthalene ring, etc. are mentioned.

  (C) Thermally diffusible dye represented by the general formula (5)

In the general formula (5), examples of each substituent represented by R ₁ and R ₂ include a halogen atom, an alkyl group (an alkyl group having 1 to 12 carbon atoms, an oxygen atom, a nitrogen atom, a sulfur atom). Alternatively, a substituent connected by a carbonyl group may be substituted, or an aryl group, alkenyl group, alkynyl group, hydroxyl group, amino group, nitro group, carboxyl group, cyano group or halogen atom may be substituted.

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

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

  The heat diffusible dyes represented by the above general formulas (3) to (5) are yellow dyes.

  (D) Thermally diffusible dye represented by the general formula (6)

(In the formula, Y ₃₁ represents an alkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a cyano group, or a perfluoroalkyl group. Z ₃₁ , Z ₃₂ represents —CR ₃₂ ═ or —N═, L ₃₁ represents a group represented by the following general formula (6-a), X ₃₁ represents an unsubstituted or substituted alkylamino group, R ₃₁ Represents a substituted or unsubstituted alkyl group, n represents an integer of 0 or more, and R ₃₂ represents a hydrogen atom or a substituent.)

（式中、Ｂ₃₁は複素環を形成するのに必要な非金属原子群を表す。）

(In the formula, B ₃₁ represents a nonmetallic atom group necessary for forming a heterocyclic ring.)

L ₃₁ represents a group represented by the general formula (6-a) and includes a nonmetallic atom group B ₃₁ necessary for forming a heterocyclic ring. Examples of the group represented by the general formula (6-a) include 2-pyrrolyl group, imidazolyl group, isothiazolyl group, isoxazolyl group, 3-pyrazolyl group, pyrazinyl group, triazolyl group, 2-pyridyl group, pyridazinyl group, and pyrimidinyl group. It represents a 3H-indolyl group, a 1H-indazolyl group, a prynyl group, an isoquinolyl group, a quinolyl group, a phthalazinyl group, a naphthyridinyl group, a quinosalinyl group, a quinazolinyl group, or the like. These heterocyclic rings may further have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an aryl group, an acyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, An amino group, a cyano group, a nitro group, and a heterocyclic group are mentioned.

X ₃₁ represents an unsubstituted or substituted alkylamino group, and examples of the substituent include an aryl group, an acyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, and a nitro group. , Hydroxyl group, carboxyl group, sulfonic acid group, sulfonamide group, acylamino group, carbamoyl group, sulfamoyl group.

R ₃₁ represents a substituted or unsubstituted alkyl group. R ₃₂ represents a hydrogen atom or a substituent, and examples of the substituent include an alkyl group, an aryl group, an acyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, and a nitro group. Can be mentioned.

  (E) Thermally diffusible dye represented by the general formula (7)

(In the formula, Y ₄₁ represents the same substituent as Y ₃₁ described above, Z ₄₁ and Z ₄₂ represent —CR ₄₃ ═ or —N═, and L ₄₁ represents the general formula (7-a), (7— b) represents a group represented by X), X ₄₁ represents an unsubstituted or substituted alkylamino group, R ₄₁ represents a substituted or unsubstituted alkyl group, R ₄₃ represents a hydrogen atom or a substituent, n represents an integer of 0 or more.)

(Wherein R ₄₂ represents a hydroxyl group, an alkoxy group, an aryloxy group, an amino group, a mercapto group, an alkylthio group or an arylthio group, R _b represents a substituent, p represents an integer of 0 to 4, and B represents -CR ₄₂ = together represents a non-metallic atomic group necessary for forming a heterocyclic ring.)

L ₄₁ represents a group represented by general formula (7-a) or (7-b), and represents a group that forms a heterocyclic ring with —CR ₄₂ ═ and B ₄₁ represented by general formula (7-a). Is a pyrrolyl group, imidazolyl group, isothiazolyl group, isoxazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, 3H-inddolyl group, 1H-indazolyl group, purinyl group, isoquinolyl group, quinolyl group Group, phthalazinyl group, naphthyridinyl group, quinosalinyl group, quinazolinyl group and the like. _R42 represents a hydroxyl group, an alkoxy group (for example, methoxy, ethoxy, butoxy, etc.), an aryloxy group, an amino group, a mercapto group, an alkylthio group, or an arylthio group. These heterocyclic rings may further have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an aryl group, an acyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, An arylthio group, an amino group, a cyano group, a nitro group, and a heterocyclic group are mentioned.

X ₄₁ represents an unsubstituted or substituted alkylamino group, and examples of the substituent include an aryl group, an acyl group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, and a nitro group. , Hydroxyl group, carboxyl group, sulfonic acid group, sulfonamide group, acylamino group, carbamoyl group, sulfamoyl group.

R ₄₁ represents a substituted or unsubstituted alkyl group. R ₄₂ represents a hydrogen atom or a substituent, the alkyl group as a substituent, an aryl group, an acyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, A nitro group etc. are mentioned.

Examples of the substituent represented by R _b include a halogen atom, an alkyl group, an aryl group, an acyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an alkylthio group, an arylthio group, an amino group, a cyano group, and a nitro group. Group, heterocyclic group and the like.

  (F) Thermally diffusible dye represented by the general formula (8)

In the general formula (8), X represents at least a bidentate chelatable group or group of atoms, and Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocycle. , R ¹ and R ² each represent a hydrogen atom, a halogen atom or a monovalent substituent. n represents 0, 1, 2;

  X is particularly preferably a group represented by the following general formula (9).

In the above general formula (9), Z ₂ represents an atomic group necessary for forming an aromatic nitrogen-containing heterocyclic ring substituted with a group containing at least one chelatable nitrogen atom. Specific examples of the ring include pyridine, pyrimidine, thiazole, imidazole and the like. These rings may further form a condensed ring with another carbocycle (such as a benzene ring) or a heterocycle (such as a pyridine ring).

  In the general formula (8), Y represents a group of atoms forming a 5-membered or 6-membered aromatic hydrocarbon ring or heterocyclic ring, and the ring may further have a substituent, and is condensed. You may have a ring. Specific examples of the ring include 3H-pyrrole ring, oxazole ring, imidazole ring, thiazole ring, 3H-pyrrolidine ring, oxazolidine ring, imidazolidine ring, thiazolidine ring, 3H-indole ring, benzoxazole ring, benzimidazole ring, A benzothiazole ring, a quinoline ring, a pyridine ring, etc. are mentioned. These rings may form a condensed ring with another carbocyclic ring (for example, benzene ring) or a heterocyclic ring (for example, pyridine ring). Examples of substituents on the ring include alkyl groups, aryl groups, heterocyclic groups, acyl groups, amino groups, nitro groups, cyano groups, acylamino groups, alkoxy groups, hydroxy groups, alkoxycarbonyl groups, halogen atoms, etc. The group may be further substituted.

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

  X represents at least a bidentate chelating group or a group of atoms, and may be any compound capable of forming a dye as the general formula (6), for example, 5-pyrazolone, imidazole, pyrazolopyrrole, pyrazolopyrazole, pyra Zoloimidazole, pyrazolotriazole, pyrazolotetrazole, barbituric acid, thiobarbituric acid, rhodanine, hydantoin, thiohydantoin, oxazolone, isoxazolone, indandione, pyrazolidinedione, oxazolidinedione, hydroxypyridone, or pyrazolopyridone are preferred .

  The heat diffusible dyes represented by the above general formulas (6) to (8) are magenta dyes.

  (G) Thermally diffusible dye represented by general formula (10)

(In the formula, R ₅₁ and R ₅₂ each represent a substituted or unsubstituted aliphatic group, R ₅₃ represents a substituent, n represents an integer of 0 to 4, and when n is 2 or more, R ₅₃ may be the same or different, and R ₅₅ and R ₅₆ each represents an alkyl group, provided that at least one of R ₅₅ and R ₅₆ represents a secondary alkyl group.

In the general formula (10), R ₅₁ and R ₅₂ represent a substituted or unsubstituted aliphatic group, and R ₅₁ and R ₅₂ may be the same or different. Examples of the aliphatic group include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, and the like. Examples of the group capable of substituting these alkyl groups include a linear or branched alkyl group, a cycloalkyl group, And alkenyl group, aryl group, heterocyclic group, halogen atom, cyano group, nitro group, hydroxy group, carbonyl group, oxycarbonyl group, carbamoyl group, alkoxy group, aryloxy group, heterocyclic oxy group, carbonyloxy group, urethane Group, sulfonyloxy group, amino group, sulfonylamino group, sulfamoylamino group, acylamino group, ureido group, sulfonyl group, sulfamoyl group, alkylthio group, arylthio group, and heterocyclic thio group.

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

It is also preferred that R ₅₁ and R _{52 form} a non-aromatic cyclic structure (eg, pyrrolidine ring, piperidine ring, morpholine ring, etc.).

R ₅₃ represents a substituent, and examples of the substituent include those of the above R ₅₁ and R ₅₂ . Among the above substituents, an alkyl group, a cycloalkyl group, an alkoxy group, and an acylamino group are preferable. n represents an integer of 0 to 4, and when n is 2 or more, the plurality of R ₅₃ may be the same or different.

R ₅₅ and R ₅₆ represents an alkyl group. At least one of R ₅₅ and R ₅₆ represents a secondary alkyl group. The secondary alkyl group of R ₅₆ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom, and is not substituted with a substituent containing other atoms. _R55 and _R56 may be the same or different.

  (H) Thermally diffusible dye represented by the general formula (11)

In the general formula (11), R ₁₁ and R ₁₂ each represents a substituted or unsubstituted aliphatic group, and R ₁₁ and R ₁₂ may be the same or different. Examples of the aliphatic group include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group. Examples of the group capable of substituting these alkyl groups include linear or branched alkyl groups, cycloalkyl groups, and alkenyl groups, aryl groups, heterocyclic groups, halogen atoms, cyano groups, nitro groups, hydroxy groups, carbonyl groups, Oxycarbonyl group, carbamoyl group, alkoxy group, aryloxy group, heterocyclic oxy group, carbonyloxy group, urethane group, sulfonyloxy group, amino group, sulfonylamino group, sulfamoylamino group, acylamino group, ureido group, sulfonyl Group, sulfamoyl group, alkylthio group, arylthio group, heterocyclic thio group and the like.

  Examples of the cycloalkyl group and the alkenyl group are the same as the above substituents.

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

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

R ₁₄ is an alkyl group, preferably a secondary or tertiary alkyl group. The alkyl group of R ₁₄ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₅ is an alkyl group, preferably a secondary or tertiary alkyl group. The alkyl group for R ₁₅ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom. They are not substituted with substituents containing other atoms.

R ₁₆ represents an alkyl group, and a particularly preferred substituent is a linear alkyl group having 3 or more carbon atoms. The alkyl group represented by R ₁₆ may be substituted, but is all substituted with a substituent consisting of a carbon atom and a hydrogen atom, and is not substituted with a substituent containing other atoms.

  The heat diffusible dyes represented by the above general formulas (10) to (11) are cyan dyes.

  The thermal transfer sheet used in the present invention forms a heat-resistant slipping layer on the side opposite to the surface on which the dye layer of the substrate is formed, and can prevent adverse effects such as sticking and printing wrinkles due to the heat of the thermal head. . The resin for forming the heat-resistant slipping layer may be a conventionally known resin, such as polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin. , Styrene-butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetate propionate resin, cellulose acetate butyrate Rate resin, cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, polycarbonate Boneto resins, and chlorinated polyolefin resins.

  The slipperiness imparting agent added to or overcoating the heat resistant slipping layer made of these resins includes phosphate ester, silicone oil, graphite powder, silicone graft polymer, fluorine graft polymer, acrylic silicone graft polymer, acrylic siloxane, aryl Silicone polymers such as siloxane can be mentioned, and it is preferable to use a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound, and a phosphate ester compound. Further, it is more preferable to add a filler.

The heat resistant slipping layer is prepared by dissolving or dispersing the above-described resin, slipperiness-imparting agent, and filler in a suitable solvent on a base material to prepare a heat resistant slipping layer forming coating solution. Can be formed by coating with a forming means such as gravure printing, screen printing, reverse roll coating using a gravure plate, and drying. The coating amount of the heat-resistant slip layer is a solid, it is preferably a ^{0.1g / m 2 ~3.0g / m 2} .

  Printing on the thermal transfer image-receiving sheet of the present invention can be performed by a general sublimation thermal transfer printing apparatus using the above-described thermal transfer sheet.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Next, the present invention will be described more specifically with reference to experimental examples.
Hereinafter, “part” or “%” is based on mass unless otherwise specified. The molecular weight is based on GPC (HLC-8020; developing solvent manufactured by Tosoh Corporation; THF flow rate; 1.0 mL / min column; G2000HXL + G3000HXL + G5000HXL), and is a number average molecular weight unless otherwise specified. Further, the glass transition temperature (Tg) was measured with a rigid pendulum type surface property tester (RPT 3000W manufactured by A & D, temperature increase rate 3 ° C./min). The degree of acetalization and the amount of hydroxyl groups were measured by infrared spectroscopy (manufactured by FTS-6000 BIORAD).

(Synthesis of polyvinyl butyral resin 1)
184 parts of polyvinyl alcohol having a saponification degree of 98.4% and a polymerization degree of 1300 and 5 parts of sodium chloride were dissolved in 2800 parts of water at 95 ° C., cooled, and 100 parts of concentrated hydrochloric acid were added. Then, 130 parts of butyraldehyde dissolved in water was added dropwise over 5 minutes, and stirred for 1 hour to precipitate. After precipitation, 200 parts of concentrated hydrochloric acid was added and reacted at 50 ° C. for 1 day. Then, it cooled to room temperature, neutralized with sodium hydrogencarbonate, and wash | cleaned with water, and the polyvinyl butyral resin 1 was obtained. The polyvinyl butyral resin 1 had an acetalization degree of 74 mol%, a hydroxyl group of 23 mol%, a Tg of 67 ° C., and a number average molecular weight of 75,000.

(Synthesis of polyvinyl butyral resin 2)
A polyvinyl butyral resin 2 having an acetalization degree of 74 mol%, a hydroxyl group of 24 mol%, a Tg of 90 ° C., and a number average molecular weight of 73,000 was obtained in the same manner as the polyvinyl butyral resin 1 except that a mixture of acetaldehyde and butyraldehyde was used instead of butyraldehyde. Obtained.

(Synthesis of polyvinyl butyral resin 3)
A polyvinyl butyral resin 3 having an acetalization degree of 70 mol%, a hydroxyl group of 28 mol%, a Tg of 89 ° C., and a number average molecular weight of 78,000 was obtained in the same manner as the polyvinyl butyral resin 1 except that a mixture of acetaldehyde and butyraldehyde was used instead of butyraldehyde. Obtained.

(Synthesis of polyvinyl butyral resin 4)
A polyvinyl butyral resin 4 having an acetalization degree of 65 mol%, a hydroxyl group of 33 mol%, a Tg of 91 ° C., and a number average molecular weight of 76000 was obtained in the same manner as the polyvinyl butyral resin 1 except that a mixture of acetaldehyde and butyraldehyde was used instead of butyraldehyde. Obtained.

  A receiving layer adhesion coating solution having the following composition was prepared.

(Receptive layer adhesion coating solution composition)
Urethane resin (Dai Nippon Ink Co., Ltd. Hydran AP-40) 60 parts Water / Isopropyl alcohol (mass ratio 1/1) 25 parts

  A coating solution for forming a receiving layer having the following composition was prepared, and the viscosity seconds were measured with a Zahn cup viscometer (No. 4, manufactured by Koiso Co., Ltd.).

(Coating liquid A composition for receiving layer formation)
Polyvinyl butyral resin 2 70 parts Metal ion-containing compound having the following structural formula 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 parts

(Coating liquid B composition for receiving layer formation)
S-REC BX-1 (polyvinyl acetal resin, manufactured by Sekisui Chemical Co., Ltd.)
Acetalization degree 72 mol%, hydroxyl group 27 mol%
Tg 92 ° C., number average molecular weight 107000 70 parts Metal ion-containing compound used in coating solution A 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1 / 1) 1250 parts

(Coating liquid C composition for receiving layer formation)
S-REC BX-L (polyvinyl acetal resin, manufactured by Sekisui Chemical Co., Ltd.)
Degree of acetalization 65 mol%, hydroxyl group 33 mol%
Tg 77 ° C., number average molecular weight 20000 70 parts Metal ion-containing compound used in coating liquid A 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1 / 1) 1250 parts

(Coating liquid D composition for receiving layer formation)
Polyvinyl butyral resin 1 70 parts Metal ion-containing compound used in coating solution A 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 Part

(Coating liquid E composition for receiving layer formation)
Polyvinyl butyral resin 3 70 parts Metal ion-containing compound used in coating solution A 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 Part

(Coating liquid F composition for receiving layer formation)
Polyvinyl butyral resin 4 70 parts Metal ion-containing compound used in coating solution A 30 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 Part

(Coating fluid G composition for receiving layer formation)
Polyvinyl butyral resin 1 70 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 parts

(Coating liquid H composition for receiving layer formation)
Polyvinyl butyral resin 2 60 parts Metal ion-containing compound having the following structural formula 40 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 parts

(Coating liquid I composition for receiving layer formation)
Polyvinyl butyral resin 2 60 parts Metal ion-containing compound having the following structural formula 40 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 parts

(Receptive layer forming coating solution J composition)
Polyvinyl butyral resin 2 60 parts Metal ion-containing compound having the following structural formula 40 parts Polyacryl-modified silicone (FS-730, manufactured by NOF Corporation) 1 part Methyl ethyl ketone / toluene (mass ratio 1/1) 1250 parts

The viscosity seconds after stirring for 30 minutes from the production of the receiving layer forming coating liquids A to J were examined according to the following evaluation criteria. Viscosity seconds here are the time from the filling of the Zahn cup (Shousha, No. 4) with the coating liquid until the liquid starts to flow until the liquid flows. The larger the viscosity seconds, the higher the viscosity. Moreover, said viscosity was measured in the environment of 20-25 degreeC and 40-70% RH.
○: The viscosity seconds is 10 seconds or less, and the viscosity is low.
Δ: Viscosity seconds are 10 seconds or more and 15 seconds or less, and the viscosity is slightly high.
X: Viscosity seconds are 15 seconds or more, and viscosity is high.

  According to Table 1, the receiving layer forming coating solution B has a high viscosity at the time of preparation and after stirring for 30 minutes, and is difficult to apply. Although the reason is unknown, the receiving layer-forming coating solution G that does not contain a metal ion-containing compound undergoes a change with time by stirring for 30 minutes, whereas the viscosity increases. The receiving layer-forming coating liquids A, C to F, and H to J contain little change over time and are excellent in coating stability.

  A dye layer coating solution having the following composition was prepared.

<Yellow dye layer forming coating solution 1>
Yellow dye having the following structural formula 1.4 parts Polyester resin (byron 290, manufactured by Toyobo Co., Ltd., molecular weight 25000) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts Silicone (FZ2101 made by Nippon Unica Co., Ltd.) 0.03 parts

<Yellow dye layer forming coating solution 2>
Yellow dye used in coating solution 1 1.4 parts Cellulose acetate butyrate resin (CAB 381-2, Eastman Chemical Co. molecular weight 38000) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts

<Magenta dye layer forming coating solution 1>
Magenta dye having the following structural formula 0.8 part Polyester resin (Molecular weight 25000 manufactured by Byron 290 Toyobo Co., Ltd.) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts Silicone (FZ2101 made by Nippon Unica Co., Ltd.) 0.03 parts

<Magenta dye layer forming coating solution 2>
Magenta dye used in the coating liquid 1 0.8 part Cellulose acetate butyrate resin (CAB381-2, molecular weight 38000, manufactured by Eastman Chemical Co.) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts

<Cyan dye layer forming coating solution 1>
Cyan dye of the following structural formula 0.9 part Polyester resin (Molecular weight 25000 manufactured by Byron 290 Toyobo Co., Ltd.) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts Silicone (FZ2101 made by Nippon Unica Co., Ltd.) 0.03 parts

<Cyan dye layer forming coating solution 2>
Cyan dye used in the coating solution 1 0.9 part Cellulose acetate butyrate resin (CAB 381-2, Eastman Chemical Co., Ltd., molecular weight 38000) 1.0 part Methyl ethyl ketone / toluene (mass ratio 1/1) 30 parts

A coating solution for forming a heat resistant slipping layer having the following composition was prepared.
<Coating fluid for forming heat resistant slipping layer>
13.6 parts of polyvinyl acetal resin (SREC BX-1 manufactured by Sekisui Chemical Co., Ltd.)
0.6 parts of polyisocyanate curing agent (Takenate D218, Takeda Pharmaceutical Company Limited)
Phosphate 0.8 parts (Plysurf A208S, Daiichi Kogyo Seiyaku Co., Ltd.)
Methyl ethyl ketone / toluene (mass ratio 1/1) 85 parts

A protective layer-forming coating solution having the following composition was prepared.
<Protective layer forming coating solution>
Acrylic resin (Dianar BR-87, manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts Methyl ethyl ketone / toluene (mass ratio 1/1) 80 parts

A coating solution for forming a heat-sensitive adhesive layer having the following composition was prepared.
<Coating liquid for heat-sensitive adhesive layer>
Polyester resin (Byron 220, manufactured by Toyobo Co., Ltd.) 20 parts Methyl ethyl ketone / toluene (mass ratio 1/1) 80 parts

(Preparation of thermal transfer image receiving sheet)
As the base sheet, synthetic paper (YUPO FPG-150, thickness 150 μm, manufactured by Oji Yuka Co., Ltd.) was used, and <Receptor Layer Adhesive Coating Solution Composition> and <Receptor Layer> having the above composition on one surface thereof The coating liquid A> for forming was applied and dried with a wire bar so as to be 0.5 g / m ² (adhesive layer) and 2.5 g / m ² (receiving layer) when dried, respectively, and the thermal transfer image-receiving sheet 1 Got.

  A thermal transfer image receiving sheet 2 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating liquid A was changed to the dye receiving layer forming coating liquid B.

  A thermal transfer image receiving sheet 3 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating liquid A was changed to the dye receiving layer forming coating liquid C.

  A thermal transfer image receiving sheet 4 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution D.

  A thermal transfer image receiving sheet 5 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution E.

  A thermal transfer image receiving sheet 6 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution F. However, in this thermal transfer image receiving sheet 6, the viscosity of the coating solution was high, and streaky unevenness due to the wire bar could be visually confirmed.

  A thermal transfer image receiving sheet 7 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution G.

  A thermal transfer image receiving sheet 8 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution H.

  A thermal transfer image receiving sheet 9 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution I.

  A thermal transfer image receiving sheet 10 was obtained in the same manner as the thermal transfer image receiving sheet 1 except that the dye receiving layer forming coating solution A was changed to the dye receiving layer forming coating solution J.

(Preparation of thermal transfer sheet)
The thermal transfer sheet 1 used for examining the abnormal transferability and the print density characteristics of the thermal transfer image receiving sheets 1 to 3 was produced under the following conditions. Gravure coating of <Yellow Dye Layer Forming Coating Liquid 1> on an easy-adhesion-treated surface of a 6 μm-thick polyethylene terephthalate film (PET) with a thickness of 6 μm as a base material results in a dry coating amount of 0.5 g / m. ² is applied and dried to form a dye layer, and the thermal transfer sheet 1 is produced. In addition, the <heat-resistant slipping layer coating solution> is previously applied to the other surface of the base material by gravure coating and dried so that the dry coating amount is 1.0 g / m ² , and the heat-resistant slipping layer is coated. Had formed.

  A thermal transfer sheet 2 was obtained in the same manner as the thermal transfer sheet 1 except that the yellow dye layer forming coating solution 1 was changed to the magenta dye layer forming coating solution 1.

  A thermal transfer sheet 3 was obtained in the same manner as the thermal transfer sheet 1 except that the yellow dye layer forming coating solution 1 was changed to the cyan dye layer forming coating solution 1.

  A thermal transfer sheet 4 was obtained in the same manner as the thermal transfer sheet 1 except that the yellow dye layer forming coating solution 1 was changed to the yellow dye layer forming coating solution 2.

  A thermal transfer sheet 5 was obtained in the same manner as the thermal transfer sheet 1 except that the yellow dye layer forming coating solution 1 was changed to the magenta dye layer forming coating solution 2.

  A thermal transfer sheet 6 was obtained in the same manner as the thermal transfer sheet 1 except that the yellow dye layer forming coating solution 1 was changed to the cyan dye layer forming coating solution 2.

The protective layer transfer sheet was produced under the following conditions. As a base material, dry-coating <Coating liquid for protective layer><Coating liquid for heat-sensitive adhesive layer> by gravure coating on the easy-adhesion-treated surface of 6-μm-thick polyethylene terephthalate film (PET) A protective layer was formed by coating and drying in this order so that both amounts were 1.0 g / m ² to prepare a protective layer thermal transfer sheet. In addition, the <heat-resistant slipping layer coating solution> is previously applied to the other surface of the base material by gravure coating and dried so that the dry coating amount is 1.0 g / m ² , and the heat-resistant slipping layer is coated. Had formed.

(Experimental example 1)
The thermal transfer image-receiving sheet 1, the thermal transfer sheets 1 to 3, and the protective layer thermal transfer sheet were combined and evaluated under the following printing conditions.

<Printing conditions>
Heating element average resistance value: 5285 (Ω)
Main scanning direction printing density; 300 dpi
Sub-scanning direction print density; 300 dpi
Applied voltage: 22 (V)
1 line cycle; 2 (msec./line)
Printing start temperature: 27 (° C)
Applied pulse (gradation control method): Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 in one line period and having a pulse length obtained by equally dividing one line period into 256 The duty ratio of the divided pulses was fixed at 96%, and the number of pulses per line period was divided from 0 to 255 into 18 steps. Thereby, different energy can be given to 18 steps. At this time, a black image can be obtained by combining the thermal transfer sheets 1 to 3 and printing in the order of 1 to 3, that is, yellow, magenta, and cyan. On the image divided into these 18 steps, a protective layer was formed by printing a protective layer transfer sheet with 255 pulses.

<Releasability>
The following evaluation criteria were used to check whether there was no thermal fusion between the thermal transfer image-receiving sheet 1 and the thermal transfer sheet at the time of printing, or whether there was a problem when peeling by hand.
○: There is almost no resistance when peeling, and there is no problem caused by thermal fusion between the thermal transfer image-receiving sheet and the thermal transfer sheet.
Δ: Resistance is felt when peeling.
X: Cannot be peeled off due to thermal fusion (abnormal transfer).

<Print density>
An image divided into 18 steps of black was formed, and a value at which the optical reflection density was maximized was measured by an optical densitometer (spectrolino manufactured by Gretag Macbeth).

<Light resistance>
About the printed matter obtained on said printing conditions, light resistance was evaluated with the xenon fade meter of the following conditions.
(Conditions for light resistance evaluation)
・ Irradiation tester: Ci35 manufactured by Atlas
・ Light source: Xenon lamp ・ Filter: Inside = IR filter
Outside = soda lime glass / black panel temperature: 45 (° C)
・ Irradiation intensity: Measurement value at 1.2 (W / m ² ) −420 (nm) ・ Irradiation energy: Integrated value at 400 (kJ / m ² ) −420 (nm)

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 Co., Ltd.), and the step in which the optical reflection density before irradiation was around 1.5 was measured according to CIE 1976. ^* , A ^* , b ^* were calculated, hue change (ΔE) was calculated by the following hue change formula, and light resistance was evaluated based on the following evaluation criteria based on ΔE.

(Hue change formula)
ΔL = after storage L ^* - before the storage L ^*
Δa = after storage a ^* - before saving a ^*
Δb = after storage b ^* - before storage b ^*
When
ΔE = (square of ΔL + square of Δa + square of Δb) square root

(Evaluation criteria)
A: ΔE is less than 10 and light resistance is good.
Δ: ΔE is 10 or more and less than 25, and light resistance is slightly inferior.
X: ΔE is 25 or more, and light resistance is inferior.

<Heat resistance>
For the printed matter obtained under the above-mentioned printing conditions, after being left in an environment of 60 ° C. for 1 week, as with light resistance, the change in the optical reflection density is changed at a step where the optical reflection density before storage is near 1.5. It was measured by an optical densitometer (spectrolino manufactured by Gretag Macbeth). The criteria for the evaluation are as follows.
(Evaluation criteria)
A: ΔE is less than 3, no bleeding is observed, and heat resistance is good.
Δ: ΔE is 3 or more, no blur is observed, and heat resistance is slightly inferior.
X: The image is blurred and the heat resistance is poor.

<Moisture resistance>
For the printed matter obtained under the above-mentioned printing conditions, the change in the optical reflection density is measured for the step where the optical reflection density before storage is about 1.5 after standing for 1 week in an environment of 50 ° C. and 80% RH. It was measured by a meter (spectrolino manufactured by Gretag Macbeth). The criteria for the evaluation are as follows.
(Evaluation criteria)
A: ΔE is less than 3, no bleeding is observed, and the moisture resistance is good.
Δ: ΔE is 3 or more, no blur is observed, and the moisture resistance is slightly inferior.
X: The image is blurred and the moisture resistance is poor.

<Blocking resistance>
Regarding the printed matter obtained under the above-mentioned printing conditions, the printed matter of each experimental example is overlapped with the image-receiving surface on which the image is formed facing the back side of the other printed matter, and this is 150 μm thick. After being left in a 60 ° C. oven for 48 hours under a load of 20 kg / cm ² in a state of being sandwiched between synthetic papers (Yupo FPG # 150 manufactured by Oji Oil Co., Ltd.), the overlapped image receiving surface and back surface are peeled off. Then, the blocking resistance was examined according to the following evaluation criteria.
(Evaluation criteria)
○: Not blocking.
Δ: Blocking.

<Preservation before printing>
The sample before printing was left in an environment of 25 ° C. and 50% RH and 50 ° C. and 80% RH for 100 hours, then printed, and the change in optical reflection density was measured with an optical densitometer (spectrolino manufactured by Gretag Macbeth). ΔE was calculated for a step in which the optical reflection density of the product left at 25 ° C. and 50% RH was around 1.5, and the pre-printing preservability was evaluated based on this ΔE based on the following evaluation criteria. The criteria for the evaluation are as follows.
(Evaluation criteria)
○: ΔE is less than 2, and the storage stability is good.
Δ: ΔE is 2 or more and less than 4, and the storage stability is slightly inferior.
X: ΔE is 4 or more, and storage stability is inferior.

(Experimental example 2)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer sheets 1 to 3 were changed to thermal transfer sheets 4 to 6.

(Experimental example 3)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 8.

(Experimental example 4)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 9.

(Experimental example 5)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 10.

(Experimental example 6)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 2.

(Experimental example 7)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 2.

(Experimental example 8)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 3.

(Experimental example 9)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 4.

(Experimental example 10)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 4.

(Experimental example 11)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 5.

(Experimental example 12)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 6.

(Experimental example 13)
Evaluation was performed in the same manner as in Experimental Example 1 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 7.

(Experimental example 14)
Evaluation was performed in the same manner as in Experimental Example 2 except that the thermal transfer image receiving sheet 1 was changed to the thermal transfer image receiving sheet 7.

  The evaluation results in Examples 1 to 14 are as shown in Table 2 below.

  In Table 2 shown above, in the samples shown in Experimental Examples 11 and 12, the degree of acetalization is less than 71, so the preservability before printing is poor.

  In Table 2 shown above, in the samples shown in Experimental Examples 8 to 10, since Tg is less than 85 ° C., blocking occurs and the preservability before printing is not sufficient. Further, in Experimental Example 8, the molecular weight is small and the releasability is poor.

  In Table 2 shown above, in the samples shown in Experimental Example 6 and Experimental Example 7, the number average molecular weight of the acetal resin contained in the receiving layer is larger than 100,000, and the viscosity at the time of coating the receiving layer is high. Since streaky unevenness originally exists on paper, streaky unevenness is also observed in the image.

  In Table 2 shown above, in the samples shown in Experimental Examples 13 to 14, since the metal ion-containing compound is not contained in the receiving layer, the storage stability of the image is not sufficient and the concentration is low. In addition, the receiving layer forming coating solution used in Experimental Examples 13 to 14 was prepared by adjusting the coating solution and measuring the viscosity in seconds measured with a Zahn cup (Ransha Co., No. 4) after stirring for 30 minutes. Is over 10 seconds and the coating stability is reduced. In the samples shown in Experimental Examples 1 to 5 and Experimental Examples 8 to 12, in the coating liquid for forming the receiving layer, an acetal resin, a thermally diffusible dye and a metal ion-containing compound capable of chelation are used. When the viscosity of the coating liquid is adjusted and prepared by adjusting the coating liquid, and after stirring for 30 minutes from the time of preparation, the viscosity seconds measured by Zahn cup (Ransha, No. 4) are Both are 10 seconds or less, the change in the viscosity of the coating solution is small, and the coating stability is excellent.

  As described above, with respect to the thermal transfer image-receiving sheet in which the receptor layer contains an acetal resin and a metal ion compound capable of chelating with a heat diffusible dye, the acetal resin is represented by the above formula. In addition, the glass transition temperature is preferably 85 ° C. or higher, and the number average molecular weight is preferably 60,000 to 100,000, thereby not only maintaining the image quality but also during printing. It is possible to obtain a thermal transfer image receiving sheet capable of preventing a change in viscosity with time, preventing a change with time of the image receiving sheet before printing, and obtaining an image of excellent quality.

It is the schematic which shows an example of the thermal transfer recording material comprised by combining the thermal transfer image receiving sheet of this invention, and the thermal transfer sheet used in combination with the thermal transfer image receiving sheet. It is the schematic which shows the other example of the thermal transfer recording material comprised by combining the thermal transfer image receiving sheet of this invention, and the thermal transfer sheet used in combination with the thermal transfer image receiving sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Thermal transfer recording material 10, 10 '... Thermal transfer image receiving sheet 11 ... Base material 12 ... Receiving layer 13 ... Back surface layer 20, 20' ... Thermal transfer sheet 21 ... Base material sheet 22 ... Dye layer 23 ... Heat-resistant slipping layer

Claims (5)

  A coating liquid for forming a receiving layer provided on a substrate of a thermal transfer image-receiving sheet contains an acetal resin and a metal ion-containing compound capable of chelating with a heat-diffusible dye, and Viscosity seconds measured with a Zahn cup (Kouaisha, No. 4) under conditions of 30 minutes from the time of preparation after adjusting the coating liquid and after the preparation are both 10 seconds or less. A coating liquid for forming a receiving layer.   A thermal transfer image-receiving sheet having a base material and a receiving layer formed on the base material and containing an acetal resin, wherein the receiving layer contains a metal ion-containing compound capable of chelating with a heat-diffusible dye In the coating liquid for forming the receptor layer, the viscosity of the coating liquid is adjusted when the coating liquid is prepared and under the conditions after stirring for 30 minutes from the time of preparation. A thermal transfer image-receiving sheet characterized in that the viscosity seconds measured by (Koushasha, No. 4) are both 10 seconds or less. The thermal transfer image receiving sheet according to claim 2, wherein the acetal resin is a compound represented by the following formula.

In the above formula, R represents a hydrocarbon which may have a substituent, l, m, and n represent mol% of each structural unit, 71 ≦ l ≦ 80, 0 ≦ m ≦ 3, 22 ≦ n ≦ 27 ranges.   The thermal transfer image-receiving sheet according to claim 3, wherein the glass transition temperature of the acetal resin is 85 ° C or higher. The thermal transfer image receiving sheet according to claim 4, wherein the number average molecular weight of the acetal resin is 60,000 or more and 100,000 or less.

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