JP5696554B2 - Thermal transfer recording medium - Google Patents

Description

  The present invention relates to a thermal transfer recording medium used in a thermal transfer type printer, and is provided with a heat-resistant slipping layer on one surface of a substrate, and an undercoat layer and a dye layer on the other surface of the substrate. The present invention relates to sequentially formed thermal transfer recording media. More specifically, the transfer sensitivity is high during high-speed printing, that is, the amount of dye used in the dye layer can be reduced, and abnormal transfer in printing can be prevented even after storage under high temperature and high humidity. Image quality that occurs at the edges, that is, the image receiving layer of the transfer object is fused to the heat-sensitive transfer recording medium, causing hue fluctuations, and as a result, the surface of the print is partially matted. The present invention relates to a thermal transfer recording medium capable of reducing the phenomenon.

  In general, a thermal transfer recording medium is an ink ribbon called a thermal ribbon, which is used in a thermal transfer type printer, and has a thermal transfer layer on one side of the substrate and heat resistance on the other side of the substrate. A slipping layer (back coat layer) is provided. Here, the heat-sensitive transfer layer is an ink layer, and the ink is sublimated (sublimation transfer method) or melted (melt transfer method) by heat generated in the thermal head of the printer, and transferred to the transfer target side. is there.

  Currently, among the thermal transfer systems, the sublimation transfer system can easily form full-color images with various functions of the printer, so digital camera self-prints, cards such as identification cards, amusement output, etc. Widely used. Along with the diversification of such applications, there is a growing demand for smaller size, higher speed, lower cost, and durability for the printed material obtained. In recent years, durability has been given to the printed material on the same side of the base sheet. 2. Description of the Related Art Thermal transfer recording media having a plurality of thermal transfer layers provided so as not to overlap protective layers and the like that have been widely used have become quite popular.

  Under such circumstances, along with the diversification and widespread use of applications, there has arisen a problem that sufficient print density cannot be obtained with the conventional thermal transfer recording medium as the printing speed of the printer further increases. In order to increase the transfer sensitivity, attempts have been made to improve the transfer sensitivity in printing by reducing the thickness of the thermal transfer recording medium. However, wrinkles are caused by heat, pressure, etc. during the manufacture of the thermal transfer recording medium or during printing. It has a problem that it occurs or in some cases breaks.

   In addition, attempts have been made to increase the printing density and transfer sensitivity in printing by increasing the dye / resin (Dye / Binder) ratio in the dye layer of the thermal transfer recording medium. In addition to being up, a part of the dye migrates to the heat-resistant slipping layer of the thermal transfer recording medium during the winding state in the manufacturing process (setback), and when the roll is turned back, the migrated dye has a different color. When the dye layer or the protective layer is re-transferred (backside back) and the contaminated layer is thermally transferred to the transfer target, the hue becomes different from the designated color, or so-called scumming occurs.

  Attempts have also been made to increase the energy at the time of image formation on the printer side, not on the thermal transfer recording medium side, but not only the power consumption increases, but also the life of the thermal head of the printer is shortened. And the transfer object are fused and so-called abnormal transfer is likely to occur. On the other hand, when a large amount of a release agent is added to the dye layer or the transfer target in order to prevent abnormal transfer, blurring of the image or background staining may occur.

  In order to solve such a problem, several methods have been proposed. For example, Patent Document 1 proposes a thermal transfer sheet having an adhesive layer containing a polyvinylpyrrolidone resin and a modified polyvinylpyrrolidone resin between a base material and a dye layer.

Patent Document 2 proposes a thermal transfer sheet having an adhesive layer composed of a thermoplastic resin of polyvinyl pyrrolidone resin or polyvinyl alcohol resin and colloidal inorganic pigment ultrafine particles between a substrate and a dye layer.
Patent Document 3 proposes a thermal transfer sheet having a base layer composed of a copolymer of vinylpyrrolidone and vinyl acetate and colloidal inorganic pigment ultrafine particles between a base material and a dye layer.

JP-A-2005-231354 JP 2006-150956 A JP 2008-155612 A

  However, when printing is performed with a high-speed printer of the sublimation transfer method on the thermal transfer recording medium proposed in Patent Document 1, abnormal transfer is not confirmed, including those stored under high temperature and high humidity. The transfer sensitivity was low, the level did not reach a sufficient level, and the shine was not sufficiently suppressed. In addition, when the same thermal printing is performed on the thermal transfer recording medium proposed in Patent Document 2, the transfer sensitivity in the printing is high and reaches a sufficient level, but is abnormally transferred when stored under high temperature and high humidity. In addition, it was not possible to sufficiently suppress the shine. Furthermore, when the printing is performed with the thermal transfer recording medium proposed in Patent Document 3, the transfer sensitivity in the printing is high and reaches a sufficient level, including those stored at high temperature and high humidity, Although there was no problem with abnormal transfer, printing unevenness was confirmed, and shine could not be sufficiently suppressed.

  As described above, in the conventional technology, there is a thermal transfer recording medium that has high transfer sensitivity in printing, does not generate abnormal transfer even when stored at high temperature and high humidity, and can be used for a high-speed printer that sufficiently improves the phenomenon of shine. What is not found is the actual situation.

  Therefore, in view of the above problems, the present invention has high transfer sensitivity at the time of high-speed printing, that is, it can reduce the dye used for the dye layer, and also has abnormalities in printing even after storage under high temperature and high humidity. Transfer can be prevented, and image quality defects occurring at high density portions, that is, hue variation occurs when the image receiving layer of the transfer target is fused to the thermal transfer recording medium, and as a result, the surface of the print is partially It is an object of the present invention to provide a heat-sensitive transfer recording medium that can reduce the phenomenon of so-called “shininess” that causes matting.

The thermal transfer recording medium according to the present invention is the thermal transfer recording medium in which a heat-resistant slipping layer is provided on one side of the substrate, and an undercoat layer and a dye layer are sequentially formed on the other side of the substrate. The pulling layer includes a water-soluble polymer containing at least a vinylpyrrolidone-vinylcaprolactam copolymer, a general formula R′Si (OR) ₃ (R ′: an alkyl group, a vinyl group, a glycidoxypropyl group, R: an alkyl group. ) Or a hydrolyzate of the organosilane, and a coating solution containing, as a main component, a composite of an acrylic polyol and an isocyanate compound.

According to the present invention, the undercoat layer comprises a water-soluble polymer containing at least a vinylpyrrolidone-vinylcaprolactam copolymer, and a general formula R′Si ( OR ) ₃ (R ′: alkyl group, vinyl group, glycid It is formed by applying and drying a coating solution containing as a main component a trifunctional organosilane represented by an oxypropyl group, R: alkyl group) or a hydrolyzate of the organosilane, and a composite of an acrylic polyol and an isocyanate compound. The transfer sensitivity is high during high-speed printing, that is, high-density printing can be obtained without increasing the amount of dye used in the dye layer, and there is no abnormal transfer in printing even after storage at high temperature and high humidity. In addition, it is possible to provide a thermal transfer recording medium in which a sufficiently satisfactory print can be obtained with less shine phenomenon.

  Further, the thermal transfer recording medium according to the present invention preferably further contains polyvinyl alcohol as the water-soluble polymer.

  In the heat-sensitive transfer recording medium according to the present invention, it is preferable that R ′ constituting the trifunctional organosilane contains an epoxy group.

  In the thermal transfer recording medium according to the present invention, it is preferable that a reaction catalyst is added to the composite.

  In the thermal transfer recording medium according to the present invention, the reaction catalyst is preferably a tin compound.

  In the thermal transfer recording medium according to the present invention, the tin compound is preferably a tin compound selected from tin chloride, tin oxychloride and tin alkoxide.

In the thermal transfer recording medium according to the present invention, in the composite further general formula _{M (OR ") n (M} : a metal _{element, R": CH 3, C} 2 H 5 or _C 3 _{H 7} N: oxidation number of metal element) or a hydrolyzate of the metal alkoxide is preferably added.

  In the thermal transfer recording medium according to the present invention, the metal in the metal alkoxide or the hydrolyzate of the metal alkoxide is preferably Si, Al, Ti, Zr or a mixture thereof.

In the thermal transfer recording medium according to the present invention, the coating amount of the undercoat layer after drying is preferably in the range of 0.10 g / m ^{2 to} 0.30 g / m ² .

In the thermal transfer recording medium of the present invention, the undercoat layer has a water-soluble polymer containing at least a vinylpyrrolidone-vinylcaprolactam copolymer, a general formula R′Si (OR) ₃ (R ′: an alkyl group, a vinyl group). A coating solution containing, as a main component, a trifunctional organosilane represented by glycidoxypropyl group, R: alkyl group) or a hydrolyzate of the organosilane and a composite of an acrylic polyol and an isocyanate compound. As a result, the transfer sensitivity during high-speed printing is high, that is, high-density printing can be obtained without increasing the amount of dye used in the dye layer, and there are abnormalities in printing even after storage at high temperature and high humidity. It is possible to obtain a sufficiently satisfactory print with no transfer and further less so-called “shine” phenomenon.

A trifunctional organosilane represented by the general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group) of the undercoat layer or a hydrolyzate of the organosilane; , a composite of acrylic polyol with an isocyanate compound of the general formula _{M (oR ") n (M} : a metal _{element, R": CH 3, C} 2 H 5 or _C 3 _H 7, n: the oxidation number of the metal element) The additive of the metal alkoxide or hydrolyzate of the above metal alkoxide is a highly reactive inorganic component, and itself undergoes a polycondensation reaction while being dried from an aqueous solution to form a chain or three-dimensional structure. In addition to forming a polymer, it is considered that a water-soluble polymer forms a complex at the molecular level.

Therefore, trifunctional organosilane represented by the general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group) of the undercoat layer or hydrolyzate of the organosilane When the composite of acrylic polyol with an isocyanate compound of the general formula _{M (oR ") n (M} : a metal _{element, R": CH 3, C} 2 H 5 or _C 3 _H 7, n: the oxidation number of the metal element ) Or a polycondensate obtained by adding a hydrolyzate of the above metal alkoxide is a transfer sensitivity at the time of high-speed printing, which is insufficient with only a water-soluble polymer containing at least a vinylpyrrolidone-vinylcaprolactam copolymer. believed to result in enhanced general formula R'Si of the undercoat layer (OR) 3 _(R ': an alkyl group, vinyl group, glycidoxy propyl Group, R: alkyl group) 3 and a functional organosilane or the hydrolyzate of the organosilane represented by a composite of acrylic polyol with an isocyanate compound of the general formula M (OR ") n (M : a metal element, R" : An additive of a metal alkoxide represented by CH ₃ , C ₂ H ₅ or C ₃ H ₇ , n: oxidation number of metal element) or a hydrolyzate of the metal alkoxide, and at least vinylpyrrolidone-vinylcaprolactam copolymer It is considered that a complex with a water-soluble polymer containing, as compared with abnormal water transfer after storage at high temperature and high humidity, which is inferior with water-soluble polymer alone, will provide an improvement.

Further, the water-soluble polymer contains at least a vinylpyrrolidone-vinylcaprolactam copolymer, further contains polyvinyl alcohol, and the metal alkoxide or the metal alkoxide hydrolyzate is converted to tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], tripropoxyaluminum or a mixture thereof, and the coating amount after drying of the undercoat layer is within the range of 0.10 g / m ² or more and 0.30 g / m ² or less, thereby enabling high-speed printing. Higher transfer sensitivity, higher density prints can be obtained, and there is no abnormal transfer in prints even after storage at high temperature and high humidity. A print can be obtained.

1 is a side sectional view showing a thermal transfer recording medium according to an embodiment of the present invention.

A thermal transfer recording medium according to an embodiment of the present invention is a thermal transfer recording medium in which a heat-resistant slipping layer is provided on one surface of a substrate, and an undercoat layer and a dye layer are sequentially formed on the other surface of the substrate. is there. The undercoat layer includes a water-soluble polymer containing at least a vinylpyrrolidone-vinylcaprolactam copolymer, a general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R : A trifunctional organosilane that can be represented by an alkyl group or the like, or a hydrolyzate of the organosilane, and a coating solution containing, as a main component, a composite of an acrylic polyol and an isocyanate compound. It is characterized by.

Also, further, the general formula _{M (OR ") n (M} : a metal _{element, R": CH 3, C} 2 H 5 alkyl group such as, n: the oxidation number of the metal element) metal alkoxide or the metal represented by It is also characterized by adding an alkoxide hydrolyzate. Here, as long as the effect of the present invention is not impaired, another component may be added, and the total of the above components is included in an amount exceeding 50% by mass as viewed from the whole when the undercoat layer is formed. However, it is preferably 80% by mass or more.

As shown in FIG. 1, the heat-sensitive transfer recording medium of the present embodiment is provided with a heat-resistant slipping layer 40 that imparts slidability with the thermal head on one surface of the substrate 10, and the other surface of the substrate 10. A coating solution containing a water-soluble polymer, a trifunctional organosilane represented by the following general formula or a hydrolyzate of the organosilane, and a composite of an acrylic polyol and an isocyanate compound as main components is prepared. The undercoat layer 20 and the dye layer 30 formed by coating and drying are sequentially formed.
General formula: R′Si (OR) ₃
(R ′: alkyl group, vinyl group, glycidoxypropyl group, etc., R: alkyl group, etc.).
Since the base material 10 is required to have heat resistance and strength not to be softened and deformed by heat pressure in thermal transfer, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, acetate, polycarbonate, polysulfone, polyimide, polyvinyl alcohol, aromatic Can be used as a composite of synthetic resin films such as polyamido polyamide, aramid, and polystyrene, and papers such as condenser paper and paraffin paper, either alone or in combination. In view of the above, a polyethylene terephthalate film is preferable. In addition, the thickness is in the range of 2 to 50 μm in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, the thickness is about 2 to 9 μm. preferable.

  Further, in the base material 10, it is possible to perform an adhesion treatment on the surface on which the heat resistant slipping layer 40 and / or the undercoat layer 20 is formed. As the adhesion treatment, known techniques such as corona treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, plasma treatment, primer treatment, etc. can be applied, and these treatments are used in combination. You can also In the present invention, it is effective to increase the adhesion between the substrate 10 and the undercoat layer 20, and a primer-treated polyethylene terephthalate film is preferable from the viewpoint of cost.

Next, the heat-resistant slipping layer 40 can be handled by a conventionally known layer. For example, a resin serving as a binder, a functional additive imparting releasability or slipperiness, a filler, a curing agent, a solvent, and the like are blended. And can be formed by coating and drying. The coating amount after drying of the heat resistant slipping layer 40 is suitably about 0.1 to 2.0 g / m ² .

  As an example of the heat resistant slipping layer 40, as the binder resin, polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, acrylic polyol, polyurethane acrylate, Examples include polyester acrylate, polyether acrylate, epoxy acrylate, nitrocellulose resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, and polycarbonate resin.

  Functional additives include natural waxes such as animal waxes and plant waxes, synthetic hydrocarbon waxes, aliphatic alcohols and acid waxes, fatty acid esters and glycerite waxes, synthetic ketone waxes, amine and amide waxes , Synthetic waxes such as chlorinated hydrocarbon wax and alpha-olefin wax, higher fatty acid esters such as butyl stearate and ethyl oleate, sodium stearate, zinc stearate, calcium stearate, potassium stearate, magnesium stearate, etc. Surfactants such as higher fatty acid metal salts, long chain alkyl phosphate esters, polyoxyalkylene alkyl aryl ether phosphate esters or phosphate esters such as polyoxyalkylene alkyl ether phosphate esters, etc. Rukoto can.

  As fillers, talc, silica, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, kaolin, clay, silicone particles, polyethylene resin particles, polypropylene resin particles, polystyrene resin particles, polymethyl methacrylate resin particles, polyurethane resin particles, etc. Can be mentioned. Examples of the curing agent include isocyanates such as tolylene diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, and derivatives thereof, but the above are not particularly limited.

Next, the undercoat layer 20 is a composite of a water-soluble polymer, a trifunctional organosilane represented by the following general formula or a hydrolyzate of the organosilane, an acrylic polyol and an isocyanate compound as essential components of the present invention. It can be formed by preparing a coating solution containing an object as a main component, and coating and drying the coating solution.
General formula: R′Si (OR) ₃
(R ′: alkyl group, vinyl group, glycidoxypropyl group, etc., R: alkyl group, etc.).
Examples of the water-soluble polymer include polyvinyl pyrrolidone-vinyl caprolactam copolymer, polyvinyl alcohol, starch, gelatin, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and sodium alginate. Among them, polyvinylpyrrolidone-vinylcaprolactam copolymer and polyvinyl alcohol are preferable, and polyvinylpyrrolidone-vinylcaprolactam copolymer is more preferable. The copolymerization ratio is preferably 20 to 80% by mass of polypyrrolidone. More preferably, it is 30-70 mass%. In addition to the polyvinyl pyrrolidone-vinyl caprolactam copolymer, polyvinyl pyrrolidone may also be included as the water-soluble polymer. Furthermore, the polyvinyl alcohol here is generally obtained by saponifying polyvinyl acetate, and so-called completely saponified polyvinyl alcohol in which only several percent of acetate groups remain from so-called partially saponified polyvinyl alcohol in which dozens of acetate groups remain. It includes up to saponified polyvinyl alcohol and is not particularly limited.

The trifunctional organosilane is represented by the following general formula such as ethyltrimethoxysilane, vinyltrimethoxysilane, glycidoxypropyltrimethoxysilane, or a hydrolyzate thereof. Of these, glycidoxytrimethoxysilane, epoxycyclohexylethyltrimethoxysilane, and the like in which an epoxy group is contained in R ′ are particularly preferable. A method for obtaining a hydrolyzate can be obtained by a known method such as a method of performing hydrolysis by directly adding an acid, an alkali or the like to a trifunctional organosilane.
General formula: R′Si (OR) ₃
(R ′ is an alkyl group, vinyl group, glycidoxypropyl group, etc., R is an alkyl group, etc.).
An acrylic polyol is a polymer compound obtained by polymerizing an acrylic acid derivative monomer, or a polymer compound obtained by copolymerizing an acrylic acid derivative monomer and other monomers, with a hydroxyl group at the terminal. It is made to react with the isocyanate group of the isocyanate compound added later. Among these, those obtained by polymerizing acrylic acid derivative monomers such as ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate alone, and acrylic polyols obtained by copolymerizing with other monomers such as styrene are preferably used. In consideration of the reactivity with the isocyanate compound, the hydroxyl value is preferably between 5 and 200 (KOHmg / g).

  The mixing ratio of the acrylic polyol and the trifunctional organosilane is preferably in the range of 1/1 to 100/1 by weight, more preferably in the range of 2/1 to 50/1.

  The dissolving and diluting solvent is not particularly limited as long as it can be dissolved and diluted. For example, esters such as ethyl acetate and butyl acetate, alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as methyl ethyl ketone, A mixture of aromatic hydrocarbons such as toluene and xylene alone and arbitrarily can be used.

  However, since an aqueous solution of hydrochloric acid or the like may be used to hydrolyze trifunctional organosilane or the like, it is more preferable to use a solvent in which isopropyl alcohol or the like and ethyl acetate that is a polar solvent are arbitrarily mixed as a cosolvent.

In addition, a reaction catalyst may be added to accelerate the reaction when the trifunctional organosilane and acrylic polyol are blended. The catalyst to be added is a tin compound such as tin chloride (SnCl ₂ , SnCl ₄ ), tin oxychloride (SnOHCl, Sn (OH) ₂ Cl ₂ ), tin alkoxide and the like in terms of reactivity and polymerization stability. Is preferred. These catalysts may be added directly at the time of blending, or may be added after being dissolved in a solvent such as methanol. If the addition amount is too small or too large, the catalytic effect cannot be obtained, so the molar ratio with respect to the trifunctional organosilane is preferably in the range of 1/10 to 1/10000, and more preferably 1/100 to 1 More preferably, it is in the range of / 2000.

  Furthermore, the isocyanate compound to be mixed is added in order to improve the adhesion to the substrate 10 by a urethane bond formed by reacting with an acrylic polyol, and mainly acts as a crosslinking agent or a curing agent. In order to achieve this, as isocyanate compounds, monomers such as aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic xylene diisocyanate (XDI), hexadiisocyanate (HMDI), and the like, These polymers and derivatives are used, and these are used alone or as a mixture.

  The blending ratio of the acrylic polyol and the isocyanate compound is not particularly limited, but if the isocyanate compound is too small, curing may be poor, and if it is too much, blocking or the like occurs and there is a problem in processing. Therefore, the blending ratio of the acrylic polyol and the insocyanate compound is preferably that the NCO group derived from the isocyanate compound is 50 times or less of the OH group derived from the acrylic polyol, and particularly preferably the NCO group and the OH group are blended in an equivalent amount. This is the case. The mixing method is not particularly limited, and a known method can be used.

Furthermore, in order to improve liquid stability at the time of liquid preparation, a metal alkoxide or a hydrolyzate thereof may be added to the composite. These metal alkoxides are tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], tripropoxyaluminum [Al (OC ₃ H ₇ ) ₃ ], etc., and the general formula M (OR ″ ) _n (M is Si, Al, Ti, A metal such as Zr, R ″ represents an alkyl group such as CH ₃ or C ₂ H ₅ ), or a hydrolyzate thereof. Among these, tetraethoxysilane, tripropoxyaluminum, or a mixture of both is preferable because it is relatively stable in an aqueous solvent. The metal alkoxide hydrolyzate may be hydrolyzed together with the trifunctional organosilane, or a metal alkoxide hydrolyzate may be added.

  The mixing ratio of the trifunctional organosilane and the metal alkoxide is preferably in the range of 10: 1 to 1:10 in terms of molar ratio from the viewpoint of liquid stability. Preferably, both are blended in equimolar amounts.

  For inks other than water-soluble resins, such trifunctional organosilanes previously hydrolyzed or trifunctional organosilanes hydrolyzed with metal alkoxides (at this time using the above-mentioned reaction catalyst) May be mixed with acrylic polyol or isocyanate compound to prepare a composite solution, or trifunctional organosilane and acrylic polyol are mixed in advance in a solvent (at this time, the above-mentioned reaction catalyst, metal alkoxide). Or a mixture of trifunctional organosilane and acrylic polyol (in this case, the above-mentioned reaction catalyst or metal alkoxide may be added). Then, an isocyanate compound is added to prepare a composite solution. Finally, it is mixed with a water-soluble resin ink to form a final undercoat layer forming coating solution.

  The mixing ratio of the water-soluble polymer and the other resin in the undercoat layer 20 is 9/1 to 1/9, and the transfer sensitivity during high-speed printing and the adhesion to the substrate 10 or the dye layer 30 are as follows. Considering it, it is preferably 8/2 to 2/8. Various additives such as tertiary amines, imidazole derivatives, carboxylic acid metal salt compounds, quaternary ammonium salts, quaternary phosphonium salts, and other accelerators, phenols, sulfurs, Antioxidants such as phosphites, leveling agents, flow regulators, catalysts, crosslinking reaction accelerators, dispersants, viscosity modifiers, stabilizers, silane coupling agents, fillers, etc. can be added. .

The coating amount after drying of the undercoat layer 20 is not generally limited, but is preferably in the range of 0.10 g / m ² or more and 0.30 g / m ² or less. If it is less than 0.10 g / m ² , the transfer sensitivity at the time of high-speed printing may be insufficient due to deterioration during lamination of the dye layer, or there may be a problem with adhesion to the substrate 10 or the dye layer 30. On the other hand, if it exceeds 0.30 g / m ² , the sensitivity of the heat-sensitive transfer recording medium itself is affected, and there is a concern that the transfer sensitivity at the time of high-speed printing will be insufficient or the shine will be deteriorated.

Although there are many unclear points, the general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group, etc.) of the undercoat layer 20 is used. 3 and a functional organosilane or the hydrolyzate of the organosilane represented, a composite of acrylic polyol with an isocyanate compound of the general formula _{M (oR ") n (M} : a metal _{element, R": CH 3, C} 2 H 5 The additive of a metal alkoxide represented by an alkyl group such as n: oxidation number of a metal element) or a hydrolyzate of the metal alkoxide is a highly reactive inorganic component, and is formed by drying from an aqueous solution. In addition to the polycondensation reaction itself forming a polymer having a chain or three-dimensional structure, it is thought that it forms a complex at the molecular level with a water-soluble polymer.

Therefore, the trifunctional organosilane represented by the general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group, etc.) of the undercoat layer 20 or the organosilane and hydrolyzate, a composite of acrylic polyol with an isocyanate compound of the general formula _{M (OR ") n (M} : a metal element, _R": CH _3, alkyl group, such as C 2 _{H 5,} n: a metal element It is considered that the additive of the metal alkoxide represented by the oxidation number) or the hydrolyzate of the metal alkoxide contributes to the improvement of the transfer sensitivity at the time of high-speed printing which is insufficient only with the water-soluble polymer. Trifunctional organosilanes represented by the general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group, etc.) There is a hydrolyzate of the organosilane, and a composite of an acrylic polyol with an isocyanate compound of the general formula _{M (OR ") n (M} : a metal element, _R": CH _3, alkyl group, such as C 2 _{H 5} N: oxidation number of metal element) or a complex of an additive of a hydrolyzate of the metal alkoxide and a water-soluble polymer, the complex is inferior to water-soluble polymer alone at high temperature and high humidity. This is considered to contribute to abnormal transfer caused by adhesion to the substrate 10 or the dye layer 30 after storage.

Next, the dye layer 30 can be handled by a conventionally known one, for example, a dye layer forming coating solution is prepared by blending a heat transferable dye, a binder, a solvent, and the like, and formed by coating and drying. About 1.0 g / m ² is appropriate. In addition, the dye layer 30 can be composed of a single layer of one color, or a plurality of dye layers containing dyes having different hues can be repeatedly formed on the same surface of the same base material in the surface order.

  The heat transferable dye of the dye layer 30 is not particularly limited as long as it is a dye that melts, diffuses, or sublimates and transfers due to heat. For example, the yellow component includes solvent yellow 56, 16, 30, 93. 33, Disperse Yellow 201, 231, 33, and the like. Examples of the magenta component include C.I. I. Disperse thread 60, C.I. I. Disperse violet 26, C.I. I. Solvent Red 27, or C.I. I. Solvent Red 19 etc. can be mentioned. As the cyan component, C.I. I. Disperse Blue 354, C.I. I. Solvent Blue 63, C.I. I. Solvent Blue 36, or C.I. I. Disperse Blue 24 and the like. As a black ink dye, it is common to perform color matching by combining the above dyes.

  As the binder of the dye layer 30, any conventionally known resin binder can be used, and is not particularly limited. Cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate are used. And vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins.

  Here, the ratio of the dye and the binder in the dye layer 30 is preferably dye / binder = 10/100 to 300/100. This is because when the dye / binder ratio is less than 10/100, the amount of dye is too small and the color development sensitivity is insufficient, and a good thermal transfer image cannot be obtained. This is because the solubility of the dye with respect to the ink is extremely lowered, so that when it becomes a thermal transfer recording medium, the storage stability is deteriorated and the dye is likely to be precipitated. Further, known additives such as isocyanate compounds, silane coupling agents, dispersants, viscosity modifiers, stabilizers and the like can be used in the dye layer or the dye layer forming coating solution as long as the performance is not impaired.

  The heat resistant slipping layer 40, the undercoat layer 20, and the dye layer 30 can be formed by applying and drying by a conventionally known application method. An example of the application method is a gravure coating method. , Screen printing, spray coating, and reverse roll coating.

<Description of image-receiving paper>
(Image receiving equipment)
As the image receiving paper substrate, papers mainly composed of cellulose pulp can be used. Examples of paper include coated paper, art paper, high-quality paper (acidic paper, neutral paper), medium-quality paper, and glassine paper.

(Insulation layer)
Furthermore, it is preferable to form a heat insulating layer containing hollow particles and an adhesive component on the image receiving paper substrate. Thermal transfer printing is performed by heating from a thermal head, and it is required that the thermal head and the image receiving paper substrate have good adhesion. Since the image receiving paper base material having the heat insulating layer has cushioning properties, adhesion with the thermal head is improved, and a more uniform image can be obtained at the time of printing. As a material for forming the walls of the hollow particles used in the heat insulating layer, acrylonitrile, vinylidene chloride, a polymer of styrene acrylate, and the like are preferably used.

  Examples of the method for producing the hollow particles include a method in which a foaming agent such as butane gas is encapsulated in the resin particles and foamed by heating, an emulsion polymerization method, and the like. As a method of heating and foaming, when using pre-foamed hollow particles in which hollow particles are pre-foamed by overheating, and after forming a heat insulating layer containing unfoamed particles by coating, etc., heat treatment such as a drying step May form a hollow structure in the heat insulating layer. From the viewpoint of easily controlling the hollow ratio and particle diameter of the hollow particles, it is generally preferable to use the already-expanded particles.

(Image receiving layer)
As the dyeing resin used in the image receiving layer, a thermoplastic resin having a high affinity for the dye and good dye dyeing property is used.

  Examples of the resin include vinyl chloride resin, urethane resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, polystyrene resin, polyacrylate resin, acrylic resin, cellulose resin, and polyamide resin. A thermoplastic resin such as a copolymer resin of a vinyl compound monomer and a monomer having a benzotriazole skeleton and / or a benzophenone skeleton, and these thermoplastic resins may be used alone or in combination of two or more. You may use together.

Among these, acrylic resins, copolymer resins of vinyl compound monomers and monomers having a benzotriazole skeleton and / or a benzophenone skeleton, and urethane resins are preferable because of excellent light resistance of printed images. This is because the urethane-based resin has a crystalline region in the molecule, and thus abnormal transfer hardly occurs.
The dyeable resin is more preferably water-soluble or water-dispersed so-called aqueous system from the viewpoint of environmental load.

  In thermal transfer printing, there is a process in which the image receiving layer on the image receiving paper substrate and the dye layer of the ink ribbon are overlaid and heated with a thermal head, and then the ink ribbon is peeled off from the image receiving layer. And releasability is also required. For this reason, it is preferable to add a release agent to the image receiving layer for the purpose of preventing fusion with the ink ribbon and improving printing runnability. Examples of the release agent to be added include silicone oil, polysiloxane graft acrylic resin, waxes, and fluorine compounds.

  It is preferable to add a crosslinking agent to the image receiving layer to improve heat resistance. As a crosslinking agent, a carbodiimide compound, an isocyanate compound, an oxazoline compound, and an organic titanium chelate compound are preferable. Among these cross-linking agents, carbodiimide-based cross-linking agents are preferable because they are highly effective in improving heat resistance, are less likely to cause running problems such as ribbon fusion during printing, and are stable in aqueous paints. . The addition amount of the carbodiimide crosslinking agent is preferably 1 to 30 parts, more preferably 3 to 25 parts, with respect to 100 parts of the resin contained in the image receiving layer. If it is less than 1 part, sufficient crosslinking effect cannot be obtained, and printing running failure may occur. If it exceeds 30 parts, the curing property of the resin may inhibit the density of the printed image.

The coating amount of the image-receiving layer is preferably from 0.5 to 5 g / ^{m 2,} more preferably 0.5-4 g / ^{m 2.} If it is less than 0.5 g / m ² , the light resistance of the image may be inferior. If it exceeds 5 g / m ² , the dye may diffuse in the image receiving layer, and image bleeding may occur.

(Coating method)
Various auxiliary agents such as wetting agents, dispersants, thickeners, antifoaming agents, colorants, antistatic agents, preservatives and the like used in the production of general coated papers are appropriately added to the above coating layers. .

  Each coating layer is a predetermined coating solution using a known coater such as a bar coater, gravure coater, comma coater, blade coater, air knife coater, gate roll coater, die coater, curtain coater, and slide bead coater. Can be formed by coating and drying each layer or two or more layers simultaneously.

  Below, the material used for each Example and each comparative example of this invention is shown. In the text, “part” is based on mass unless otherwise specified.

<Ink other than water-soluble resin>
(A) In a diluting solvent, 2- (epoxycyclohexyl) ethyltrimethylsilane (hereinafter abbreviated as EETMS) and acrylic polyol are mixed in an amount of 5.0 times (weight ratio) with respect to EETMS, and tin chloride (as a catalyst) Add SnCl ₂ ) / methanol solution (prepared to 0.003 mol / g) to 1/135 mol with respect to EETMS and stir. Next, a mixed solution obtained by diluting a mixed solution of triisyl isocyanate (hereinafter abbreviated as TDI) as an isocyanate compound so that NCO groups are equivalent to OH groups of the acrylic polyol to an arbitrary concentration is referred to as a composite solution A.

(B) In a dilute solvent, EETMS and tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ : hereinafter abbreviated as TEOS) are mixed at a molar ratio of 1: 1, and acrylic polyol is mixed with EETMS and TEOS. 2.5 times the amount by weight of the above, and tin catalyst (SnCl ₂ ) / methanol solution (prepared to 0.003 mol / g) as a catalyst to EETMS and TEOS Add and stir to 1/400 mol. 0.1 N HCl was added thereto, stirred and hydrolyzed, and then a mixed solution obtained by diluting the mixed solution of TDI so that the NCO group was equivalent to the OH group of the acrylic polyol to an arbitrary concentration is used as a composite solution B.

<Preparation of substrate with heat-resistant slip layer>
As a base material, a polyethylene terephthalate film with a single-sided easy adhesion treatment of 4.5 μm is used, and a heat resistant slipping layer coating solution having the following composition is applied to the non-easy adhesion treatment surface by a gravure coating method so that the coating amount after drying is 1 After coating and drying so as to be 0.0 g / m ² , the substrate with a heat-resistant slipping layer was obtained by aging in a 40 ° C. environment for 1 week.

<Heat resistant slipping layer coating solution>
Acrylic polyol resin 12.5 parts Polyoxyalkylene alkyl ether / phosphate ester 2.5 parts talc 6.0 parts 2,6-tolylene diisocyanate prepolymer 4.0 parts toluene 50.0 parts methyl ethyl ketone 20.0 parts ethyl acetate 5.0 parts <Preparation of transfer object>
<Preparation of image receiving paper substrate>
Art paper having a thickness of 180 g / m ² was used as the image receiving paper substrate.

<Formation of heat insulation layer>
On the image receiving paper substrate, the following composition heat insulating layer coating solution is applied by a gravure coating method so that the coating amount after drying is 10 g / m ² , dried, and then aged in a 40 ° C. environment for 1 week. Thus, an image receiving paper with a heat insulating layer was obtained.

<Insulation layer coating solution>
45 parts of pre-expanded hollow particles made of a copolymer mainly composed of acrylonitrile and methacrylonitrile (average particle diameter: 3.2 μm, volume hollow ratio: 85%)
Polyvinyl alcohol 10 parts Vinyl chloride vinyl acetate copolymer resin dispersion 45 parts (vinyl chloride / vinyl acetate = 70/30, Tg 64 ° C.)
200 parts of water <Formation of image receiving layer>
By applying and drying the following composition image-receiving layer coating solution on the heat insulation layer by gravure coating method so that the coating amount after drying becomes 4 g / m ^2, and then aging in a 40 ° C. environment for 1 week. An image receiving layer was obtained.

<Image-receiving layer coating solution>
97 parts of urethane resin (glass transition temperature: -20 ° C)
Associative urethane thickener 1 part sulfonic acid surfactant 2 parts water 200 parts (Example 1)
The undercoat layer coating solution-1 having the composition shown below is applied to the surface of the base material with a heat-resistant slip layer by a gravure coating method so that the coating amount after drying is 0.2 g / m ² and dried. As a result, an undercoat layer was formed. Subsequently, a dye layer coating solution having the following composition is applied onto the undercoat layer by a gravure coating method so that the coating amount after drying is 0.7 g / m ² , and the dye layer is formed by drying. The thermal transfer recording medium of Example 1 was obtained.

<Undercoat layer coating solution-1>
Solid content of composite solution A 6.2 parts polyvinylpyrrolidone-vinylcaprolactam copolymer 1.1 parts [copolymerization ratio (molar ratio): 1/1]
Polyvinyl alcohol 1.1 parts 0.1N hydrochloric acid 53.8 parts Pure water 33.9 parts Isopropyl alcohol 3.9 parts <Dye layer coating solution>
C. I. Solvent Blue 63 6.0 parts Polyvinyl acetal resin 4.0 parts Toluene 45.0 parts Methyl ethyl ketone 45.0 parts (Example 2)
In the thermal transfer recording medium produced in Example 1, the thermal recording transfer medium of Example 2 was obtained in the same manner as in Example 1 except that the undercoat layer was changed to the undercoat layer coating liquid-2 of the following composition. .

<Undercoat layer coating solution-2>
Solid content of composite solution A 6.2 parts polyvinylpyrrolidone-vinylcaprolactam copolymer 2.2 parts [copolymerization ratio (molar ratio): 1/1]
0.1N hydrochloric acid 53.8 parts pure water 33.9 parts isopropyl alcohol 3.9 parts (Example 3)
In the thermal transfer recording medium produced in Example 1, the thermal recording transfer medium of Example 3 was obtained in the same manner as in Example 1, except that the undercoat layer was changed to the undercoat layer coating solution-3 of the following composition. .

<Undercoat layer coating solution-3>
Solid content of composite solution B 1.8 parts polyvinylpyrrolidone-vinylcaprolactam copolymer 1.2 parts [copolymerization ratio (molar ratio): 1/1]
Pure water 64.0 parts ethyl alcohol 29.1 parts isopropyl alcohol 3.9 parts (Example 4)
In the heat-sensitive transfer recording medium produced in Example 1, the example was applied in the same manner as in Example 1 except that the undercoat layer was applied and dried so that the coating amount after drying was 0.05 g / m ^2. No. 4 thermal recording transfer medium was obtained.

(Example 5)
In the heat-sensitive transfer recording medium produced in Example 1, the Example was applied in the same manner as in Example 1 except that the undercoat layer was applied and dried so that the coating amount after drying was 0.35 g / m ^2. No. 5 thermal recording transfer medium was obtained.

(Comparative Example 1)
After forming the undercoat layer on the easy-adhesion treated surface of the substrate with a heat-resistant slipping layer, the same dye layer coating solution as in Example 1 is dried on the easy-adhesive treated surface by a gravure coating method. The dye layer was formed by coating and drying so that the amount of coating was 0.7 g / m ² , and the thermal transfer recording medium of Comparative Example 1 was obtained.

(Comparative Example 2)
The undercoat layer coating solution-4 having the following composition is applied to the surface of the base material with a heat-resistant slip layer by a gravure coating method so that the coating amount after drying is 0.2 g / m ² and dried. As a result, an undercoat layer was formed. Subsequently, on the undercoat layer, the same dye layer coating solution as in Example 1 was applied and dried by the gravure coating method so that the coating amount after drying was 0.7 g / m ² . A dye layer was formed to obtain a thermal transfer recording medium of Comparative Example 2.

<Undercoat layer coating solution-4>
Polyvinylpyrrolidone-vinylcaprolactam copolymer 3.0 parts
[Copolymerization ratio (molar ratio): 1/1]
Pure water 87.3 parts isopropyl alcohol 9.7 parts (Comparative Example 3)
The undercoat layer coating solution-5 having the following composition was applied to the surface of the base material with a heat-resistant slip layer by a gravure coating method so that the coating amount after drying was 0.2 g / m ² and dried. As a result, an undercoat layer was formed. Subsequently, on the undercoat layer, the same dye layer coating solution as in Example 1 was applied and dried by the gravure coating method so that the coating amount after drying was 0.7 g / m ² . A dye layer was formed to obtain a thermal transfer recording medium of Comparative Example 3.

<Undercoat layer coating solution-5>
Solid content of composite solution A 6.2 parts Polyvinyl alcohol 2.2 parts 0.1 N hydrochloric acid 53.8 parts Pure water 33.9 parts Isopropyl alcohol 3.9 parts (Comparative Example 4)
The undercoat layer coating solution-6 of the following composition is applied to the surface of the base material with a heat-resistant slip layer by a gravure coating method so that the coating amount after drying is 0.2 g / m ² and dried. As a result, an undercoat layer was formed. Subsequently, on the undercoat layer, the same dye layer coating solution as in Example 1 was applied and dried by the gravure coating method so that the coating amount after drying was 0.7 g / m ² . A dye layer was formed to obtain a thermal transfer recording medium of Comparative Example 4.

<Undercoat layer coating solution-6>
Tetraethoxysilane 10.4 parts 0.1N hydrochloric acid 89.6 parts <Evaluation of adhesion of dye layer at room temperature>
Regarding the thermal transfer recording media of Examples 1 to 5 and Comparative Examples 1 to 4, a cellophane tape having a width of 18 mm and a length of 150 mm was applied on the dye layer of the thermal transfer recording medium stored at room temperature, and immediately thereafter. Table 1 shows the results of evaluation by examining the presence or absence of the dye layer adhering to the cellophane tape when peeled off. The evaluation was performed according to the following criteria.
○: Adhesion of the dye layer is not recognized.
Δ: Adhesion of the dye layer is very slightly recognized.
X: Adhesion of the dye layer is observed on the entire surface.

<Evaluation of adhesion of dye layer after storage at high temperature and high humidity>
Regarding the thermal transfer recording media of Examples 1 to 5 and Comparative Examples 1 to 4, the dye layers of the thermal transfer recording media were stored for 72 hours at 40 ° C. and 90% RH, and then stored for 24 hours at room temperature. Table 1 shows the results of evaluation by examining the presence or absence of the dye layer adhering to the cellophane tape side when a cellophane tape having a width of 18 mm and a length of 150 mm is applied to the top and then immediately peeled off. The evaluation was performed according to the same standard as the evaluation at room temperature.

<Print evaluation>
Regarding the thermal transfer recording media of Examples 1 to 5 and Comparative Examples 1 to 4, the thermal transfer recording media stored at room temperature, and after being stored in a 40 ° C. 90% RH environment for 72 hours, further 24 at normal temperature. Table 1 shows the results of evaluating the maximum reflection density and the presence or absence of abnormal transfer by performing solid printing with the following conditions using a thermal simulator using a thermal transfer recording medium and a transfer medium that have been stored for a long time. The maximum reflection density is a value measured with X-Rite 528.

<Printing conditions>
Printing environment: 23 ° C, 50% RH
Applied voltage: 29V
Line cycle: 0.7msec
Print density: main scanning 300 dpi sub-scanning 300 dpi
<Abnormal transcription evaluation>
The abnormal transcription was evaluated according to the following criteria.

○: Abnormal transfer to the transfer medium is not observed.
(Triangle | delta): The abnormal transcription | transfer to a to-be-transferred material is recognized very slightly.
X: Abnormal transfer to the transfer medium is observed on the entire surface.

<Electricity evaluation>
Moreover, the evaluation of shine was performed according to the following criteria.

  ○: No shine is recognized.

(Triangle | delta): Tekari is recognized partially.
X: Tekari is clearly recognized.

As can be seen from the results shown in Table 1, a water-soluble polymer containing at least a polyvinylpyrrolidone-vinylcaprolactam copolymer and a general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl) Formed by applying and drying a coating solution containing, as a main component, a trifunctional organosilane represented by a group such as R: an alkyl group, or a hydrolyzate of the organosilane, and a composite of an acrylic polyol and an isocyanate compound. The thermal transfer recording media of Examples 1, 2, 4, and 5 provided with an undercoat layer clearly have a higher speed printing than the thermal transfer recording medium of Comparative Example 1 provided with no undercoat layer. It can be seen that the transfer sensitivity is high.

In addition, a water-soluble polymer containing at least a polyvinylpyrrolidone-vinylcaprolactam copolymer and a general formula R′Si (OR) ₃ (R ′: alkyl group, vinyl group, glycidoxypropyl group, etc., R: alkyl group, etc. 3 and a functional organosilane or the hydrolyzate of the organosilane represented by), a composite of acrylic polyol with an isocyanate compound of the general formula _{M (oR ") n (M} : a metal _{element, R": CH 3, C} 2 alkyl groups such as H _5, n: a coating solution obtained by adding hydrolyzate of the metal alkoxide or the metal alkoxide represented by the oxidation number) of a metal element coated, provided the undercoat layers formed by drying It can be seen that the thermal transfer recording medium of Example 3 also has high transfer sensitivity during high-speed printing.

It can be seen that the adhesion of the dye layer during normal temperature storage and high temperature / high humidity storage and abnormal transfer in printing are not problematic in practice. Among them, it can be seen from the highest reflection density of the room temperature storage product and the high temperature / high humidity storage product of Examples 1 and 3 that the water-soluble polymer preferably contains polyvinyl alcohol. Moreover, it turns out that tetraethoxysilane is more preferable from the adhesiveness of the dye layer after high temperature and high humidity storage of Example 1. Further, in the thermal transfer recording medium of Example 4, the adhesiveness after storage at a high temperature and high humidity is somewhat lowered because the coating amount of the undercoat layer is less than 0.10 g / m ² , and the transfer sensitivity is also improved. It can be seen that the effect is somewhat reduced. In addition, it can be seen that the effect of the transfer sensitivity is lowered in the thermal transfer recording medium of Example 5 because the coating amount of the undercoat layer exceeds 0.30 g / m ² .

  In contrast, in the thermal transfer recording medium of Comparative Example 2, the undercoat layer was provided only with the polyvinylpyrrolidone-vinylcaprolactam copolymer, which is a water-soluble polymer, as compared with the thermal transfer recording medium of Example 1. As a result, it can be seen that the transfer sensitivity at room temperature storage is low. Further, it can be seen that the thermal transfer recording medium of Comparative Example 3 has poor shine compared to the thermal transfer recording medium of Example 1. It can also be seen that the thermal transfer recording medium of Comparative Example 4 has a lower transfer sensitivity and lower thermal transfer as a result of providing the undercoat layer only with tetraethoxysilane as compared with the thermal transfer recording medium of Example 1. .

  The thermal transfer recording medium obtained according to the present invention is an ink ribbon used in a sublimation transfer type printer, and in addition to the high speed and high functionality of the printer, various images can be easily formed in full color. Are widely used, such as self-prints, cards such as identification cards, and amusement output.

DESCRIPTION OF SYMBOLS 10 ... Base material 20 ... Undercoat layer 30 ... Dye layer 40 ... Heat-resistant slipping layer

Claims (9)

In a thermal transfer recording medium in which a heat-resistant slipping layer is provided on one surface of a substrate, and an undercoat layer and a dye layer are sequentially formed on the other surface of the substrate, the undercoat layer comprises at least vinylpyrrolidone-vinylcaprolactam. A coating solution containing a water-soluble polymer containing a copolymer, a trifunctional organosilane represented by the following general formula or a hydrolyzate of the organosilane, and a composite of an acrylic polyol and an isocyanate compound as a main component is applied. A thermal transfer recording medium formed by drying.
General formula: R′Si (OR) ₃
(R ': alkyl group, vinyl group, glycidoxypropyl group, R: alkyl group)   The thermal transfer recording medium according to claim 1, wherein the water-soluble polymer further contains polyvinyl alcohol.   The thermal transfer recording medium according to claim 1, wherein an epoxy group is contained in R ′ constituting the trifunctional organosilane.   The thermal transfer recording medium according to any one of claims 1 to 3, wherein a reaction catalyst is added to the composite.   The thermal transfer recording medium according to claim 4, wherein the reaction catalyst is a tin compound.   6. The thermal transfer recording medium according to claim 5, wherein the tin compound is a tin compound selected from tin chloride, tin oxychloride and tin alkoxide. 7. The thermal transfer recording medium according to claim 1, wherein a metal alkoxide represented by the following general formula or a hydrolyzate of the metal alkoxide is further added to the composite. .
General formula: M (OR " ) _n
(M: metal element, R ″ : CH ₃ , C ₂ H ₅ or C ₃ H ₇ , n: oxidation number of metal element)   8. The metal in the metal alkoxide or the hydrolyzate of the metal alkoxide is at least one of Si, Al, Ti, Zr, or a mixture thereof. Thermal transfer recording medium. 9. The feeling according to claim 1, wherein the coating amount of the undercoat layer after drying is in the range of 0.10 g / m ^{2 to} 0.30 g / m ² . Thermal transfer recording medium.

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