JP6379990B2 - Thermal transfer recording medium - Google Patents

Description

  The present invention relates to a thermal transfer recording medium used in a thermal transfer printer.

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

  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, as the printing speed of the printer is further increased with the diversification and widespread use of the applications, the conventional thermal transfer recording medium cannot obtain a sufficient printing density, and the thermal head of the printer The problem of rapid wear has arisen.
In order to increase the transfer sensitivity in order to increase the print density, attempts have been made to improve the transfer sensitivity in printing by reducing the thickness of the thermal transfer recording medium. There is a problem that wrinkles are generated due to pressure or the like and breakage occurs in some cases.

  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 rewinding is performed, the migrated dye has another 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, a hue different from the designated color or so-called background staining 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 stains may occur.

In order to solve such a demand, for example, Patent Document 1 proposes a thermal transfer sheet having an adhesive layer containing polyvinyl pyrrolidone and modified polyvinyl pyrrolidone between a base material and a dye layer.
However, when the thermal transfer recording medium proposed in Patent Document 1 is printed by a recent high-speed printer using a sublimation transfer method, a sufficient print density cannot be obtained or abnormal transfer occurs during thermal transfer. However, when printing, wrinkles are generated due to heat and pressure, the thermal head of the printer has a short life, and other problems occur, so that satisfactory quality cannot be obtained.

JP-A-2005-231354

  SUMMARY An advantage of some aspects of the invention is that it provides a thermal transfer recording medium capable of performing printing more appropriately.

In order to solve the above problems, one embodiment of the present invention includes a base material, a heat-resistant slip layer formed on one surface of the base material, a dye layer formed on the other surface of the base material, A thermal transfer recording medium having an undercoat layer formed between the other side and the dye layer, wherein the undercoat layer has a storage elastic modulus G ′ at 100 ° C. of 1.0E + 06 N / m ² or more. Yes, including a copolymer of polyester having a sulfonic acid group in the side chain, an acrylic having at least one of glycidyl group and carboxyl group, and polyvinylpyrrolidone, and the heat resistant slipping layer is made of SiC, Si at 120 ° C. _The dynamic friction coefficient μ _k for each of ₃ N ₄ and SiON is 0.18 or less.

According to one aspect of the present invention, since the storage elastic modulus G ′ at 100 ° C. of the undercoat layer is 1.0E + 06 N / m ² or more, abnormal transfer can be suppressed. Moreover, since the copolymer of polyester and an acryl was used, solvent resistance and dye barrier property can be improved. Furthermore, the heat-resistant lubricating layer, _SiC at _{120 ℃, Si 3 N 4,} SiON respectively because of the dynamic friction coefficient mu _k and 0.18 or less for the can life of the thermal head of the printer. Therefore, according to one embodiment of the present invention, printing can be performed more appropriately.

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

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the thermal transfer recording medium 1 includes a substrate 10, a heat-resistant slip layer 40 formed on one surface of the substrate 10, and a dye layer formed on the other surface of the substrate 10. 30 and an undercoat layer 20 formed between the other surface of the substrate 10 and the dye layer 30.
Since the thermal transfer recording medium 1 is likely to be wrinkled at the time of printing if it is deformed by the thermal pressure in the thermal transfer, it is preferable that the elongation when the thermal pressure is applied is small. In particular, when the thermal transfer recording medium 1 (sample) is heated at a load of 5000 N / m ^{2 in} the MD (Machine Direction) direction and is heated while being heated, the temperature T at which the elongation rate becomes 1% becomes 205 ° C. or higher. Wrinkles are unlikely to occur. The above-mentioned temperature T is TMA / SS6100 manufactured by SII, and is cooled from −5 ° C./min from room temperature to 0 ° C. and then heated to 260 ° C. at 5 ° C./min. ) By measuring the displacement.

  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 It is possible to use a synthetic resin film such as polyamide, aramid, or polystyrene, and paper such as condenser paper or paraffin paper, alone or in combination. Among these, a polyethylene terephthalate film is preferable in view of physical properties, workability, cost, and the like.

The thickness of the substrate 10 can be in the range of 2 μm to 50 μm in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, it is 2 μm to 9 μm. The following grades are preferred.
Moreover, in the base material 10, it is also possible to perform an adhesion treatment on the surface on which the heat resistant slipping layer 40 and the undercoat layer 20 are 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

Next, the heat-resistant slipping layer 40 is a layer formed on one surface of the substrate 10, and is a layer that gives the thermal transfer recording medium 1 slipperiness with the thermal head. The heat-resistant slipping layer 40 in the present embodiment needs to have a dynamic friction coefficient μ ′ for each of SiC, Si ₃ N ₄ , and SiON at 120 ° C. of 0.18 or less. As a result, thermal head wear due to contact with the thermal transfer recording medium 1 during printing is suppressed, leading to a longer life of the thermal head. On the other hand, when the dynamic friction coefficient μ ′ at 120 ° C. exceeds 0.18, the life of the thermal head is shortened due to wear by the heat-resistant sliding layer 40. Note that SiC, Si ₃ N ₄ , and SiON are general thermal head materials.

The dynamic friction coefficient μ ′ is the dynamic friction coefficient μ with the heat-resistant slipping layer 40 of the thermal transfer recording medium 1 in a state where SiC, Si ₃ N ₄ , and SiON are heated to 120 ° C. using HEIDON tribogear 14 manufactured by Shinto Kagaku. 'Is measured at a load of 100 g and a scanning speed of 10 mm / min.
The heat resistant slipping layer 40 preferably has an effect of suppressing the elongation of the thermal transfer recording medium 1 due to heat pressure. As described above, since the thermal transfer recording medium 1 is likely to be wrinkled during printing if it is deformed by the heat pressure in the thermal transfer, the thermal transfer recording medium 1 (sample) is particularly subjected to a load of 5000 N / m ^{2 in} the MD direction. It is desirable that the temperature T at which the elongation rate of the thermal transfer recording medium 1 in the MD direction becomes 1% when heated while being pulled is 205 ° C. or higher. However, the undercoat layer 20 and the dye layer 30 are formed on one surface of the substrate 10. In a state where the layers are stacked, the temperature T may be less than 205 ° C. In this case, by using the heat-resistant slipping layer 40 that is small in deformation due to heat pressure, deformation due to heat pressure of the entire heat-sensitive transfer recording medium 1 is suppressed, and the temperature T of the heat-sensitive transfer recording medium 1 becomes 205 ° C. or higher. (It is necessary to use the heat-resistant slipping layer 40 such that the temperature T is 205 ° C. or higher).

The above-mentioned temperature T is TMA / SS6100 manufactured by SII, and is cooled from −5 ° C./min from room temperature to 0 ° C. and then heated to 260 ° C. at 5 ° C./min. ) By measuring the displacement.
The heat resistant slipping layer 40 is prepared, for example, by appropriately preparing a coating solution for forming the heat resistant slipping layer 40 by blending a resin serving as a binder, a functional additive, a filler, a curing agent, a solvent, and the like, and applying and drying. Can be formed. Coating amount after drying of the heat-resistant lubricating layer 40, the degree and 2.0 g / ^{m 2} or less at a 0.1 g / ^{m 2} or more is suitable. Here, the coating amount after drying of the heat-resistant slipping layer 40 refers to the amount of solid content remaining after the coating liquid for forming the heat-resistant slipping layer 40 is applied and dried, and drying of the undercoat layer 20 described later. Similarly, the subsequent coating amount and the coating amount after drying of the dye layer 30 also indicate the solid content remaining after the coating liquid is applied and dried.

The above functional additive has an effect of imparting releasability and slipperiness, and the above-mentioned dynamic friction coefficient μ _k can be controlled by the blending ratio of the functional additive. Although it is possible to lower the dynamic friction coefficient mu _k by increasing the compounding ratio, material because a problem occurs by the compounding ratio is too high the material, necessary to the compounding ratio appropriately selected and 0.18 or less is there.
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 laurate, zinc stearate, calcium stearate, potassium stearate, stearin Higher fatty acid metal salt such as magnesium acid phosphate, long chain alkyl phosphate ester, polyoxyalkylene alkyl aryl ether phosphate ester, or phosphate ester such as polyoxyalkylene alkyl ether phosphate ester, etc. It may be mentioned surfactants.

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, and tetramethylxylene diisocyanate, and derivatives thereof, but are not particularly limited.

Next, the undercoat layer 20 has a storage elastic modulus G ′ at 100 ° C. of 1.0E + 06 N / m ² or more, a polyester having a sulfonic acid group in the side chain, and at least one of a glycidyl group and a carboxyl group. It is formed by coating and drying a coating solution containing a copolymer of acrylic and having polyvinyl pyrrolidone as a main component. By forming such an undercoat layer 20, abnormal transfer does not occur, and a high-density print can be obtained without increasing the dye used for the dye layer 30.

Abnormal transfer is a phenomenon in which the dye layer 30 peels from the substrate 10 during thermal transfer, and the dye layer 30 and the transfer target are fused. It has been found by the inventors that the temperature at which abnormal transfer is likely to occur is approximately 100 ° C. Therefore, when the storage elastic modulus G ′ at 100 ° C. is less than 1.0E + 06 N / m ² , the adhesion between the dye layer 30 and the undercoat layer 20 is lowered, and abnormal transfer is likely to occur. More preferably, it is 1.0E + 08 N / m ² or more and less than 1.0E + 10 N / m ² . Within this range, transfer sensitivity can be further improved, and wrinkling during printing can be suppressed.

Moreover, in this embodiment, 100 degreeC of the subbing layer 20 which has a copolymer of polyester which has a sulfonic acid group in a side chain, an acryl which has at least one kind of glycidyl group and a carboxyl group, and polyvinylpyrrolidone as a main component. Even when the storage elastic modulus G ′ at 1.0 does not satisfy 1.0E + 06 N / m ² or more, the storage elastic modulus G ′ at 100 ° C. is 1 by further blending other resins or using a known crosslinking agent or curing agent. If it becomes 0.0E + 06 N / m ² or more, it can be used as the undercoat layer 20.

Examples of known crosslinking agents and curing agents include, but are not particularly limited to, isocyanate compounds, silane coupling agents, chelate compounds, melamines, epoxy compounds, aziridine compounds, and carbodiimide compounds.
The dynamic viscoelastic property of the undercoat layer 20 is defined by the loss tangent of the dynamic viscoelastic spectrum or the loss tangent and the storage elastic modulus at a specific frequency and a specific temperature. It is defined by the temperature showing the peak of loss tangent in the elastic spectrum or the peak value of loss tangent. In this embodiment, the dynamic viscoelasticity was measured at a frequency of 10 Hz, a temperature range of 20 ° C. to 200 ° C., and a test piece having a temperature increase rate of 3 ° C./min at about 0.1 mm.

  The undercoat layer 20 is required not only to prevent abnormal transfer but also to have a dye barrier property for improving the transfer sensitivity, and further to have a solvent resistance for laminating the dye layer 30 usually made of a solvent system on the undercoat layer 20. It is done. In this embodiment, it is necessary that the main component of the undercoat layer 20 is composed of a copolymer of a polyester having a sulfonic acid group in the side chain, an acrylic having at least one of glycidyl group and carboxyl group, and polyvinylpyrrolidone. It is.

  Here, as long as the effects of the present embodiment are not impaired, the main component is a copolymer of a polyester having a sulfonic acid group in the side chain and an acrylic having at least one glycidyl group or carboxyl group, and polyvinylpyrrolidone. In addition, it means that other components may be added, and the copolymer is meant to be contained in an amount of more than 50% by mass as viewed from the whole when the undercoat layer 20 is formed, but preferably 80% by mass or more. It is.

  As other components, known additives such as colloidal inorganic pigment ultrafine particles, isocyanate compounds, silane coupling agents, dispersants, viscosity modifiers, stabilizers and the like can be used. The colloidal inorganic pigment ultrafine particles are conventionally known, for example, silica (colloidal silica), alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or hydrate thereof, suspect boehmite, etc. Etc.), aluminum silicate, magnesium silicate, magnesium carbonate, magnesium oxide, titanium oxide and the like.

  The polyester component having a sulfonic acid group is indispensable for obtaining adhesion and solvent resistance with the substrate 10, and the acrylic component having any one of glycidyl group and carboxyl group is necessary for obtaining dye barrier properties and solvent resistance. When the respective components are simply blended, the compatibility between the acrylic component and the polyester component is not good, so that not only the stability as the material is lacking, but also the adhesion with the base material 10 possessed by the polyester component, the acrylic component Both the solvent resistance and dye barrier property possessed by are not obtained, resulting in lower performance than when each component is used alone. This is because an incompatible sea-island structure is formed by blending incompatible polymers with each other, and a polyester component having adhesion and an acrylic component having dye barrier properties are locally present (as a whole of the undercoat layer 20). It is thought that there are sometimes places with poor adhesion and places with poor barrier properties.

On the other hand, by copolymerizing the acrylic component and the polyester component, the incompatibility is improved and phase separation does not occur, and since the acrylic component and the polyester component exist in the entire undercoat layer 20, each component is It is considered that the functions (adhesion, solvent resistance, dye barrier properties) possessed effectively.
The dicarboxylic acid component, which is a copolymer component of the polyester having a sulfonic acid group in the side chain, contains an ester-forming sulfonic acid alkali metal salt compound as an essential component, phthalic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, Aromatic dicarboxylic acids such as 2,5-dimethylterephthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, orthophthalic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid Examples thereof include acids and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

As the dicarboxylic acid component other than the ester-forming sulfonic acid alkali metal salt compound, an aromatic dicarboxylic acid is preferable, and since the aromatic nucleus of the aromatic dicarboxylic acid has a high affinity with a hydrophobic plastic, adhesion is improved, There is an advantage of excellent degradability. In particular, terephthalic acid and isophthalic acid are preferable.
Examples of the ester-forming alkali metal salt of sulfonic acid include alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalenic acid-2,7-dicarboxylic acid (alkali sulfonic acid alkali). Metal salts) and their ester-forming derivatives, and the sodium salt of 5-sulfoisophthalic acid and its ester-forming derivatives are more preferably used. By having a sulfonic acid group, the solvent resistance is improved.

  Examples of the diglycol component that is a copolymerization component of polyester include diethylene glycol and an aliphatic group having 2 to 8 carbon atoms or an alicyclic glycol group having 6 to 12 carbon atoms. Specific examples of the aliphatic having 2 to 8 carbon atoms or the alicyclic glycol having 6 to 12 carbon atoms include ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, Neopentyl glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,6-hexanediol , P-xylylene glycol, triethylene glycol and the like, and one or more of these may be used in combination.

Polyester having a sulfonic acid group is essential for obtaining adhesion between the base material 10 and the undercoat layer 20, but when used alone, high transfer sensitivity cannot be obtained, and therefore an acrylic component is copolymerized. There is a need.
Examples of the acrylic component include a glycidyl group-containing radical polymerizable unsaturated monomer alone, a carboxyl group-containing radical polymerizable unsaturated monomer alone, or other radical polymerizable unsaturated monomers that can be copolymerized with the above monomers.

  In the present embodiment, a glycidyl group-containing radical polymerizable unsaturated monomer or a carboxyl group-containing radical polymerizable unsaturated monomer is required. This is because the glycidyl group and the carboxyl group have a dye barrier property because they are not compatible with the dye. That is, transfer sensitivity is improved by containing a glycidyl group and a carboxyl group. Furthermore, the solvent resistance to ketone solvents such as acetone and methyl ethyl ketone and ester solvents such as ethyl acetate and butyl acetate is improved.

Examples of the glycidyl group-containing radical polymerizable unsaturated monomer include glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether.
Examples of the carboxyl group-containing radical polymerizable unsaturated monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, 5- Examples thereof include carboxypentyl (meth) acrylate.

Radical polymerizable unsaturated monomers that can be copolymerized with glycidyl group or carboxyl group-containing radical polymerizable unsaturated monomers include vinyl esters, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, unsaturated nitriles, allyl compounds, and nitrogen-containing systems. Examples include vinyl monomers, hydrocarbon vinyl monomers, and vinyl silane compounds.
Examples of vinyl esters include vinyl propionate, vinyl stearate, higher tertiary vinyl esters, vinyl chloride, and vinyl bromide. Examples of unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, butyl maleate, octyl maleate, butyl fumarate, Octyl fumarate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, Examples thereof include polyethylene glycol dimethacrylate and polyethylene glycol diacrylate.

Examples of unsaturated carboxylic acid amides include acrylamide, methacrylamide, methylol acrylamide, and butoxymethylol acrylamide. An example of the unsaturated nitrile is acrylonitrile.
Examples of the allyl compound include allyl acetate, allyl methacrylate, allyl acrylate, and diallyl itaconate. Examples of the nitrogen-containing vinyl monomer include vinyl pyridine and vinyl imidazole, and examples of the hydrocarbon vinyl monomer include ethylene, propylene, hexene, octene, styrene, vinyl toluene, and butadiene. Examples of the vinylsilane compound include dimethylvinylmethoxysilane, dimethylvinylethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyldimethoxysilane.

  Moreover, it is preferable that the copolymerization ratio of polyester and acrylic is 20: 80-40: 60 by weight ratio. That is, the weight ratio of the polyester in the copolymer of polyester and acrylic is preferably 20% or more and less than 40%. When the polyester component is less than 20%, a high printing density is obtained, but the adhesion with the substrate 10 tends to be insufficient, and when the polyester component is 40% or more, the adhesion is sufficient, but the printing density is high. This is because it tends to decrease. Therefore, by setting the weight ratio of the polyester in the copolymer of polyester and acrylic to 20% or more and less than 40%, it is possible to improve the printing density while improving the adhesion with the substrate 10. .

  The polyester can be obtained by a known production technique in which a dicarboxylic acid and diglycol are esterified or subjected to a polycondensation reaction after an ester exchange reaction, but the production method is not limited at all. The copolymerization of polyester and acrylic is also produced by a known production technique, but the production method is not limited at all. For example, in the case of emulsion polymerization, a method of emulsifying and polymerizing an acrylic monomer using a polyester dispersion or aqueous solution, and a method of polymerizing while dropping an acrylic monomer into a polyester dispersion or aqueous solution can be mentioned.

  As a result of further investigation by the inventors, by including polyvinylpyrrolidone in the copolymer of polyester and acrylic, polyester having a sulfonic acid group in the side chain and acrylic having at least one of glycidyl group and carboxyl group It was found that the transfer sensitivity was increased as compared with the case where each of the copolymer and polyvinylpyrrolidone were used alone. This is considered because polyvinyl pyrrolidone was present in the vicinity of the polyester portion having a sulfonic acid group in the copolymer having the property of easily adsorbing the dye, thereby preventing the adsorption of the dye.

  Moreover, it is preferable that the copolymer of polyester and acrylic and polyvinylpyrrolidone are 70: 30-30: 70 by weight ratio. That is, the weight ratio of the copolymer in the undercoat layer 20 (total weight of copolymer and polyvinylpyrrolidone) is preferably 30% or more and less than 70%. This is because when the polyvinyl pyrrolidone content is less than 30%, it is difficult to obtain a high printing density, and when the polyvinyl pyrrolidone content is 70% or more, it is difficult to obtain a high printing density and the storage stability is lowered. Therefore, by increasing the weight ratio of the copolymer with respect to the total weight of the copolymer of polyester and acrylic and polyvinylpyrrolidone to 30% or more and less than 70%, the printing density is improved and the storage stability is improved. can do.

The decrease in storage stability is due to the hygroscopicity of polyvinylpyrrolidone.
Examples of polyvinyl pyrrolidone include homopolymers of vinyl pyrrolidone such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, and copolymers thereof. Further examples include modified polyvinyl pyrrolidone. Modified polyvinylpyrrolidone is a copolymer of an N-vinylpyrrolidone monomer and another monomer. The form of copolymerization is not particularly limited, such as random copolymerization, block copolymerization, and graft copolymerization. The N-vinyl pyrrolidone monomer mentioned above refers to N-vinyl pyrrolidone (N-vinyl-2-pyrrolidone, N-vinyl-4-pyrrolidone, etc.) and derivatives thereof. Examples thereof include those having a substituent on the pyrrolidone ring such as vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3,3,5-trimethylpyrrolidone, N-vinyl-3-benzylpyrrolidone. However, it is not particularly limited.

  Examples of the monomer component copolymerized with the N-vinylpyrrolidone monomer include the following vinyl polymerizable monomers. For example, (meth) acrylic monomers such as (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate and isopropyl (meth) acrylate, unsaturated carboxylic acids such as fumaric acid, maleic acid and itaconic acid, vinylcaprolactam , Ethylene, propylene, vinyl chloride, vinyl acetate, vinyl alcohol, styrene, vinyl toluene, divinylbenzene, vinylidene chloride, ethylene tetrafluoride, vinylidene fluoride, and the like.

  The polyvinyl pyrrolidone used in the undercoat layer 20 in this embodiment preferably has a K value in the Fickencher formula of 30 or more and 100 or less. Particularly preferred is 60 or more and 90 or less. When polyvinyl pyrrolidone having a K value of less than 30 is used, the effect of improving the transfer sensitivity in printing is reduced, and when it is 100 or more, the viscosity of the coating solution is improved, and the coating suitability is lowered. Therefore, when the undercoat layer 20 has a K value of 30 or more and 100 or less in the Fickencher's formula, it is possible to improve the coating suitability while improving the transfer sensitivity in printing.

The coating amount of the undercoat layer 20 after drying is not generally limited, but is preferably 0.1 g / m ² or more and 0.30 g / m ² or less. Particularly preferred is 0.05 g / ^{m 2} or more 0.30 g / ^{m 2} or less. If it is less than 0.05 g / m ² , the undercoat layer 20 is deteriorated when the dye layer 30 is laminated, so that the transfer sensitivity at the time of high-speed printing is insufficient, and there is a concern that the adhesion to the substrate 10 or the dye layer 30 has a problem. . On the other hand, if it exceeds 0.30 g / m ² , the print density is saturated regardless of the sensitivity of the thermal transfer recording medium 1 itself. Therefore, it is preferable that it is 0.30 g / m < ² > or less from a viewpoint of cost. Therefore, the coating amount after drying the undercoat layer 20 is set to 0.10 g / m ² or more and 0.30 g / m ² or less, thereby improving the transfer sensitivity during high-speed printing and improving the cost. can do.

Next, the dye layer 30 can be handled by a conventionally known one. For example, the dye layer 30 is formed by blending a heat transferable dye, a binder, a solvent, and the like to prepare a coating solution for forming the dye layer 30, and applying and drying the coating solution. Is done. An appropriate coating amount of the dye layer 30 after drying is about 1.0 g / m ² . In addition, the dye layer 30 can be composed of a single layer of one color, or a plurality of dye layers 30 containing dyes having different hues can be repeatedly formed on the same surface of the same base material 10 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, as yellow components, 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. Ink dyes are generally toned by combining the respective dyes.

  As the binder contained in the dye layer 30, any conventionally known resin binder can be used, and is not particularly limited, but cellulose-based materials such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate Examples thereof include vinyl resins such as resins, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins.

  Here, the blending ratio of the dye and the binder in the dye layer 30 is preferably (dye) / (binder) = 10/100 or more and less than 300/100 on a mass basis. This is because when the ratio of (dye) / (binder) is less than 10/100, the amount of dye is too small and the color development sensitivity becomes insufficient, and a good thermal transfer image cannot be obtained, and this ratio is 300/100. If it exceeds, the solubility of the dye in the binder will be extremely lowered, so that when it becomes the thermal transfer recording medium 1, the storage stability is deteriorated and the dye is likely to precipitate. The dye layer 30 may contain known additives such as an isocyanate compound, a silane coupling agent, a dispersant, a viscosity modifier, and a stabilizer as long as the performance is not impaired.

  The heat-resistant slip layer 40, the undercoat layer 20, and the dye layer 30 can be formed by applying and drying by a conventionally known application method. Examples of the application method include a gravure coating method, a screen printing method, a spray coating method, and a reverse roll coating method.

Below, the material used for each Example of this embodiment and each comparative example is shown. In the text, “part” is based on mass unless otherwise specified. Further, the present embodiment is not limited to the examples.
Example 1
<Preparation of the base material 10 with the heat resistant slipping layer 40>
A 4.5 μm polyethylene terephthalate film is used as the base material 10, and the heat-resistant slipping layer coating solution-1 having the following composition is applied to one surface thereof by a gravure coating method, and the coating amount after drying is 1.0 g. The substrate 10 with the heat-resistant slipping layer 40 was obtained by aging for 1 week in a 40 ° C. environment after coating at / m ² and drying at 100 ° C. for 1 minute.

<Heat resistant slipping layer coating solution-1>
Acrylic polyol resin 13.1 parts Zinc laurate 1.5 parts Talc 6.3 parts 2,6-Tolylene diisocyanate prepolymer 4.2 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

<Method for producing sulfonic acid group-containing polyester / glycidyl group-containing acrylic copolymer>
As a reaction catalyst, 854 parts of dimethyl terephthalate, 355 parts of 5-sodiumsulfoisophthalic acid, 186 parts of ethylene glycol, 742 parts of diethylene glycol and a reaction catalyst in a four-necked flask equipped with a distillation tube, a nitrogen introduction tube, a thermometer, and a stirrer , 1 part of zinc acetate was added, the temperature was raised from 130 ° C. to 170 ° C. over 2 hours, 1 part of antimony trioxide was added, and the temperature was raised from 170 ° C. to 200 ° C. over 2 hours to carry out the esterification reaction It was. Subsequently, the temperature was gradually raised and the pressure was reduced, and finally a polycondensation reaction was performed at a reaction temperature of 250 ° C. and a vacuum degree of 1 mmHg or less for 1 to 2 hours to obtain a polyester. The obtained polyester is dissolved in pure water, glycidyl methacrylate is added as a glycidyl group-containing acrylic monomer so that the weight ratio of the polyester is 30:70, and potassium persulfate is further added as a polymerization initiator. It was created.

  Next, pure water and the monomer emulsion were charged into a reaction vessel equipped with a cooling tube, and after sufficient deoxygenation by blowing nitrogen gas for 20 minutes, the temperature was gradually raised over 1 hour, and 75 to 85 The reaction was carried out for 3 hours while maintaining the temperature, and a sulfonic acid group-containing polyester / glycidyl group-containing acrylic copolymer was obtained. Further, a sulfonic acid group-containing polyester / carboxyl group-containing acrylic copolymer and a polyester acrylic copolymer having various polymerization ratios were obtained in the same manner.

On the surface of the substrate 10 with the heat-resistant slip layer 40 on which the heat-resistant slip layer 40 is not applied, an undercoat layer coating solution-1 having the following composition is applied by a gravure coating method to a coating amount after drying of 0.20 g / The undercoat layer 20 was formed by applying to m ² and drying at 100 ° C. for 2 minutes. Subsequently, on the undercoat layer 20, the dye layer coating solution-1 having the following composition was applied by a gravure coating method so that the coating amount after drying was 0.70 g / m ² , and 90 ° C. for 1 minute. By drying, the dye layer 30 was formed, and the thermal transfer recording medium 1 of Example 1 was obtained.

<Undercoat layer coating solution-1>
Sulfonic acid group-containing polyester /
Glycidyl group-containing acrylic copolymer (30:70) 2.5 parts Polyvinylpyrrolidone (K value 60) 2.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts <Dye layer coating solution-1>
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 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-2 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, a thermal recording transfer medium of Example 2 was obtained.
<Heat resistant slipping layer coating solution-2>
Acrylic polyol resin 12.8 parts Zinc laurate 2.0 parts Talc 6.1 parts 2,6-Tolylene diisocyanate prepolymer 4.1 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Example 3)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-3 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, the thermal recording transfer medium of Example 3 was obtained.
<Heat resistant slipping layer coating solution-3>
Acrylic polyol resin 12.2 parts Zinc laurate 3.0 parts Talc 5.9 parts 2,6-tolylene diisocyanate prepolymer 3.9 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

Example 4
In the heat-sensitive transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating solution-4 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, a thermal recording transfer medium of Example 4 was obtained.
<Heat resistant slipping layer coating solution-4>
Acrylic polyol resin 11.7 parts Zinc laurate 4.0 parts Talc 5.6 parts 2,6-tolylene diisocyanate prepolymer 3.7 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Example 5)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating solution-5 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, the thermal recording transfer medium of Example 5 was obtained.
<Heat resistant slipping layer coating solution-5>
Acrylic polyol resin 11.1 parts Zinc laurate 5.0 parts Talc 5.3 parts 2,6-Tolylene diisocyanate prepolymer 3.6 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Example 6)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-6 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, the thermal recording transfer medium of Example 6 was obtained.
<Heat resistant slipping layer coating solution-6>
Acrylic polyol resin 13.7 parts Zinc laurate 3.0 parts Talc 4.0 parts 2,6-tolylene diisocyanate prepolymer 4.4 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Example 7)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-7 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, the thermal recording transfer medium of Example 7 was obtained.
<Heat resistant slipping layer coating solution-7>
Acrylic polyol resin 11.0 parts Zinc laurate 3.0 parts Talc 7.5 parts 2,6-Tolylene diisocyanate prepolymer 3.5 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Example 8)
<Preparation of the base material 10 with the heat resistant slipping layer 40>
A 4.5 μm polyethylene terephthalate film is used as the substrate 10, and the heat resistant slipping layer coating solution having the composition of the heat resistant slipping layer coating solution 3 described above is applied to one surface thereof by a gravure coating method after drying. After apply | coating so that an application quantity might be 1.0 g / m < ² > and drying at 100 degreeC for 1 minute, the base material 10 with the heat resistant slipping layer 40 was obtained by aging for 1 week in a 40 degreeC environment.

Application of the undercoat layer coating solution of the composition of the undercoat layer coating solution-1 described above on the surface of the substrate 10 with the heat resistant slip layer 40 on which the heat resistant slip layer 40 is not applied, by drying using a gravure coating method. The undercoat layer 20 was formed by applying the coating solution so that the amount was 0.20 g / m ² and drying at 100 ° C. for 2 minutes. Subsequently, the dye coating solution having the composition of the dye layer coating solution-1 described above is applied onto the undercoat layer 20 by a gravure coating method so that the coating amount after drying is 0.70 g / m ² . The dye layer 30 was formed by drying at 90 ° C. for 1 minute, and the thermal transfer recording medium 1 of Example 8 was obtained.

Example 9
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 9 was prepared in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-2 of the following composition. Obtained.
<Undercoat layer coating solution-2>
Sulfonic acid group-containing polyester /
Glycidyl group-containing acrylic copolymer (30:70) 2.5 parts Polyvinylpyrrolidone (K value 90) 2.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 10)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 10 was prepared in the same manner as in Example 8, except that the undercoat layer 20 was changed to the undercoat layer coating solution-3 of the following composition. Obtained.

<Undercoat layer coating solution-3>
Sulfonic acid group-containing polyester /
Glycidyl group-containing acrylic copolymer (30:70) 2.5 parts Polyvinylpyrrolidone (K value 90) 2.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 11)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 11 was prepared in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-4 of the following composition. Obtained.
<Undercoat layer coating solution-4>
Sulfonic acid group-containing polyester /
Glycidyl group-containing acrylic copolymer (30:70) 3.5 parts Polyvinylpyrrolidone (K value 60) 1.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 12)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 12 was prepared in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-5 of the following composition. Obtained.
<Undercoat layer coating solution-5>
Sulfonic acid group-containing polyester /
Glycidyl group-containing acrylic copolymer (30:70) 1.5 parts Polyvinylpyrrolidone (K value 60) 3.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 13)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 13 was prepared in the same manner as in Example 8, except that the undercoat layer 20 was changed to the undercoat layer coating solution-6 of the following composition. Obtained.
<Undercoat layer coating solution-6>
Sulfonic acid group-containing polyester /
Carboxyl group-containing acrylic copolymer (30:70) 2.5 parts Polyvinylpyrrolidone (K value 90) 2.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 14)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 14 was prepared in the same manner as in Example 8, except that the undercoat layer 20 was changed to the undercoat layer coating solution-7 of the following composition. Obtained.
<Undercoat layer coating solution-7>
Sulfonic acid group-containing polyester /
Carboxyl group-containing acrylic copolymer (20:80) 2.50 parts Polyvinylpyrrolidone (K value 90) 2.50 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 15)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Example 15 was prepared in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-8 of the following composition. Obtained.
<Undercoat layer coating solution-8>
Sulfonic acid group-containing polyester /
Carboxyl group-containing acrylic copolymer (40:60) 2.5 parts Polyvinylpyrrolidone (K value 90) 2.5 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Example 16)
In the thermal transfer recording medium 1 produced in Example 10, the undercoat layer 20 was coated and dried so that the coating amount after drying was 0.03 g / m ² , in the same manner as in Example 8, A heat-sensitive recording transfer medium of Example 16 was obtained.
(Example 17)
In the thermal transfer recording medium 1 produced in Example 10, the undercoat layer 20 was coated and dried so that the coating amount after drying was 0.35 g / m ² , in the same manner as in Example 8, A heat-sensitive recording transfer medium of Example 17 was obtained.

(Comparative Example 1)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-8 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, a thermal recording transfer medium of Comparative Example 1 was obtained.
<Heat resistant slipping layer coating solution-8>
Acrylic polyol resin 13.6 parts Zinc laurate 0.5 parts Talc 6.5 parts 2,6-Tolylene diisocyanate prepolymer 4.4 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Comparative Example 2)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating liquid-9 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was formed. In the same manner as in Example 1, a thermal recording transfer medium of Comparative Example 2 was obtained.
<Heat-resistant slip layer coating solution-9>
Acrylic polyol resin 13.3 parts Zinc laurate 1.0 part Talc 6.4 parts 2,6-Tolylene diisocyanate prepolymer 4.3 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Comparative Example 3)
In the thermal transfer recording medium 1 produced in Example 1, except that the heat-resistant slipping layer coating solution -10 having the following composition was applied to the base material 10 when the base material 10 with the heat-resistant slipping layer 40 was prepared. In the same manner as in Example 1, a thermal recording transfer medium of Comparative Example 3 was obtained.
<Heat resistant slipping layer coating solution-10>
Acrylic polyol resin 9.1 parts Zinc laurate 3.0 parts Talc 10.0 parts 2,6-tolylene diisocyanate prepolymer 2.9 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

(Comparative Example 4)
Without forming the undercoat layer 20 on the surface of the base material 10 with the heat-resistant slip layer 40 on which the heat-resistant slip layer 40 is not applied, the same dye layer coating solution as in Example 8 is obtained by a gravure coating method. The dye layer 30 was formed by coating and drying so that the coating amount after drying was 0.7 g / m ² , and the thermal transfer recording medium 1 of Comparative Example 4 was obtained.

(Comparative Example 5)
A thermal recording transfer medium of Comparative Example 5 was obtained in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-8 of the following composition.
<Undercoat layer coating solution-8>
Polyvinylpyrrolidone (K value 30) 5.0 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Comparative Example 6)
A thermal recording transfer medium of Comparative Example 6 was obtained in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-9 having the following composition.
<Undercoat layer coating solution-9>
Polyvinylpyrrolidone (K value 90) 5.0 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Comparative Example 7)
A thermal recording transfer medium of Comparative Example 7 was obtained in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-10 of the following composition.
<Undercoat layer coating solution-10>
Sulfonic acid group-containing polyester resin 5.00 parts Pure water 47.5 parts Isopropyl alcohol 47.5 parts

(Comparative Example 8)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Comparative Example 8 was prepared in the same manner as in Example 8, except that the undercoat layer 20 was changed to the undercoat layer coating solution-11 of the following composition. Obtained.
<Undercoat layer coating solution-11>
Glycidyl group-containing acrylic resin 5.0 parts Pure water 47.5 parts Isopropyl alcohol 47.5 parts

(Comparative Example 9)
A thermal recording transfer medium of Comparative Example 9 was obtained in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-12 of the following composition.
<Undercoat layer coating solution-12>
Sulfonic acid group-containing polyester /
Carboxyl group-containing acrylic copolymer (30:70) 5.0 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts

(Comparative Example 10)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Comparative Example 10 was prepared in the same manner as in Example 8, except that the undercoat layer 20 was changed to the undercoat layer coating solution 13 of the following composition. Obtained.
<Undercoat layer coating solution-13>
Glycidyl group-containing acrylic resin 7.0 parts Sulfonic acid group-containing polyester resin 3.0 parts Pure water 45.0 parts Isopropyl alcohol

(Comparative Example 11)
In the thermal transfer recording medium 1 produced in Example 8, the thermal recording transfer medium of Comparative Example 11 was prepared in the same manner as in Example 8 except that the undercoat layer 20 was changed to the undercoat layer coating solution-14 of the following composition. Obtained.
<Undercoat layer coating solution-14>
Methoxymethylated nylon (Methoxymethylation rate of about 30%) 5.0 parts Pure water 57.0 parts Isopropyl alcohol 38.0 parts <Preparation of transfer object>
A white foamed polyethylene terephthalate film having a diameter of 188 μm is used as the substrate 10, and an image-receiving layer coating solution having the following composition is applied to one surface thereof by a gravure coating method so that the coating amount after drying is 5.0 g / m ^2. By applying and drying, a transfer object for thermal transfer was produced.

<Image-receiving layer coating solution>
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 19.5 parts Amino-modified silicone oil 0.5 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts <Evaluation of dynamic friction coefficient>
Table 1 shows the results of measuring the dynamic friction coefficient μ _k of SiC, Si ₃ N ₄ , and SiON at 120 ° C. of the heat-resistant sliding layers of the thermal transfer recording media 1 of Examples 1 to 7 and Comparative Examples 1 to 3. The dynamic friction coefficient μ _k was measured using a HEIDON tribogear 14 manufactured by Shinto Kagaku at a load of 100 g and a scanning speed of 100 mm / min.

<Evaluation of temperature at which the elongation becomes 1%>
The measurement results of the temperature T at which the elongation rate is 1% when the thermal transfer recording medium 1 (sample) of the thermal transfer recording medium 1 of Examples 1 to 7 and Comparative Examples 1 to 3 is heated while being pulled under load. Table 1 shows. The temperature T was cooled from room temperature to 0 ° C. at −5 ° C./min at −5 ° C./min while pulling the thermal transfer recording medium 1 (sample) with a load of 5000 N / m ^{2 in} the MD direction using TII / SS6100 manufactured by SII. It was derived by measuring the displacement of the thermal transfer recording medium 1 (sample) when heated to 260 ° C. at 5 ° C./min.
The temperature T of the sheet in which the undercoat layer 20 and the dye layer 30 were sequentially layered on one surface of the substrate 10 was 200 ° C.

<Evaluation of thermal head wear>
The thermal transfer recording media 1 of Examples 1 to 7 and Comparative Examples 1 to 3 were used, and three kinds of unused thermal heads of SiC, Si ₃ N ₄ , and SiON were used, and a thermal simulator was used under the following conditions. 10000 sheets of solid printing were carried out continuously.
Printing environment: 23 ° C, 50% RH
Applied voltage: 29V
Line cycle: 0.9msec
Print density: main scanning 300 dpi sub-scanning 300 dpi
And the cross-sectional shape of the thermal head after use was observed with Nikon NEXIV VMR, and the wear due to rubbing against the heat resistant slipping layer 40 was confirmed. The evaluation results of wear are shown in Table 1. The evaluation of wear was based on the following criteria.
A: The maximum wear is less than 1 μm. The life of the thermal head can be maintained at a level that is not problematic in practice.
X: The maximum wear exceeds 1 μm. The life of the thermal head is shortened.

<Print wrinkle evaluation>
Using the thermal transfer recording media 1 of Examples 1 to 7 and Comparative Examples 1 to 3, printing evaluation was performed using each of three types of thermal heads of SiC, Si ₃ N ₄ and SiON. As evaluation of wrinkles, printing evaluation was performed at a speed of 10 inch / sec for two patterns with different printing energies of 24V and 27V. For 24V, the 255 gradations are divided, the high density side is 255 gradations, the low gradation side is 46 gradations, the medium gradation side is 178 gradations, and the high gradation side is the print density of 255 gradations. Was measured. Regarding the print density, measurement was performed on black.
Note that the evaluation of printing defects due to wrinkles was performed according to the following criteria. If wrinkles do not occur at a voltage of 24V, there is no practical problem.
◯: No print defects due to wrinkles on the printed material ×: Print defects due to wrinkles on the printed material

<Print evaluation>
Table 2 shows the results of performing the solid printing with the thermal simulator using the thermal transfer recording media 1 of Examples 8 to 17 and Comparative Examples 4 to 11, and evaluating the maximum reflection density. The maximum reflection density is a value measured with X-Rite 528.
The printing conditions are as follows.
Printing environment: 23 ° C, 50% RH
Applied voltage: 29V
Line cycle: 0.9msec
Print density: main scanning 300 dpi sub-scanning 300 dpi

<Abnormal transcription evaluation>
With respect to the thermal transfer recording media 1 of Examples 8 to 17 and Comparative Examples 4 to 11, the thermal transfer recording medium 1 cured at room temperature and the transfer target were used, and the solid was printed with a thermal simulator in an environment of 48 ° C. and 5%. Printing was performed to evaluate the presence or absence of abnormal transfer. The results are shown in Table 2.
The abnormal transcription was evaluated according to the following criteria. Δ or more is a level where there is no practical problem.
○: Abnormal transfer to the transfer object is not observed Δ: Abnormal transfer to the transfer object is very slight ×: Abnormal transfer to the transfer object is observed on the entire surface

<Measurement of dynamic viscoelasticity>
Evaluation was performed under the following conditions using a viscoelastic spectrometer (EXSTAR DMS6100). The results are shown in Table 2.
Frequency: 10Hz
Temperature range: 20 ° C to 200 ° C
Temperature increase rate: 3 ° C / min
Test piece: about 0.1 mm

From the results shown in Table 1, the thermal transfer recording medium 1 of Examples 1 to 5 the dynamic friction coefficient mu _k pairs SiC at 120 ° C. of the heat-resistant lubricating layer 40 is 0.18 or less was rubbed with heat-resistant lubricating layer 40 There is no problem in the wear of the SiC thermal head. On the other hand, the wear due to the rubbing and Comparative Examples 1 and 2 heat-resistant lubricating layer 40 of the thermal head in the dynamic friction coefficient mu _k pairs SiC at 120 ° C. of the heat-resistant lubricating layer 40 is more than 0.18 is 1μm up to wear The service life has been shortened.

Further, from the results shown in Table 1, the thermal transfer recording media 1 of Examples 1 to 5 in which the dynamic friction coefficient μ _{k of} the heat-resistant slipping layer 40 at 120 ° C. with respect to Si ₃ N ₄ is 0.18 or less are Si ₃ N. There is no problem with wear due to rubbing against the heat-resistant sliding layer 40 of the thermal head ₄ . On the other hand, in Comparative Examples 1 and 2 in which the dynamic friction coefficient μ _k of the heat resistant slipping layer 40 at 120 ° C. with respect to Si ₃ N ₄ exceeds 0.18, the wear due to rubbing against the heat resistant slipping layer 40 of the thermal head is maximum. Wear exceeds 1 μm and the life is shortened.

Further, from the results shown in Table 1, Examples 1 to 5 the dynamic friction coefficient mu _k pairs SiON at 120 ° C. of the heat-resistant lubricating layer 40 is 0.18 or less, a thermal transfer recording medium 1 of Comparative Example 2 of SiON There is no problem with wear due to rubbing against the heat-resistant slip layer 40 of the thermal head. On the other hand, the wear due to the rubbing with the Comparative Example the heat-resistant lubricating layer 40 of the thermal head in the 1 dynamic friction coefficient mu _k pairs SiON at 120 ° C. of the heat-resistant lubricating layer 40 is more than 0.18 greater than 1μm maximum wear The life is shortened.

As described above, the thermal head life of any thermal head of SiC, Si ₃ N ₄ , or SiON is practical when the dynamic friction coefficient μ _{k of the} heat resistant slipping layer 40 at 120 ° C. with respect to the head material is 0.18 or less. I knew that I could keep the level without any problems. It is considered that wear of the thermal head is suppressed by reducing the friction between the thermal head that becomes a high temperature during printing and the heat-resistant slip layer 40 heated thereby.

From the results shown in Table 1, the temperature T at which the elongation rate of the thermal transfer recording medium 1 in the MD direction of the thermal transfer recording medium 1 when heated by pulling a load of 5000 N / m ² in the MD direction is 1% is obtained. In Examples ₃ , 6, and 7 at 205 ° C. or higher, no printing wrinkle is generated when printing is performed using any of the thermal heads of SiC, Si ₃ N ₄ , and SiON. On the other hand, in the comparative example 3 where the temperature T is lower than 205 ° C., printing wrinkles are generated. From this, it was found that if the temperature T is 205 ° C. or higher, printing wrinkles do not occur. This seems to be because, when the temperature T is 205 ° C. or higher, the elongation of the thermal transfer recording medium 1 when the heat pressure is applied is sufficiently small.

  As described above, the temperature T of the sheet in which the undercoat layer 20 and the dye layer 30 were sequentially layered on one surface of the substrate 10 was 200 ° C., but the heat resistant slipping layer 40 was added to this. Since the temperature T of the thermal transfer recording medium 1 of 3, 6, and 7 is 205 ° C. or higher, the heat-resistant slipping layer 40 of Examples 3, 6, and 7 has an effect of raising the temperature T, that is, the heat pressure. There is an effect of suppressing the elongation when applied, and it is considered that the print wrinkles are suppressed.

From the results shown in Table 2, Examples 8 to 17 and Comparative Examples 5 to 7, 9, and 11 in which the storage elastic modulus G ′ at 100 ° C. of the resin constituting the undercoat layer 20 is 1.0E + 06 N / m 2 or more. It was found that the thermal transfer recording medium 1 of Example 1 did not cause abnormal transfer as compared with Comparative Examples 8 and 10 in which the storage elastic modulus G ′ at 100 ° C. was less than 1.0E + 06 N / m ² . Also, the storage modulus G 100 ° C. 'is 1.0E + 08N / ^{m 2} or more embodiments 8,10,12～17, Comparative Example 11 has a storage modulus G 100 ° C.' is 1.0E + 06N / ^{m 2} or more Compared with Examples 9 and 11 and Comparative Examples 5, 7, and 9 which are less than 1.0E + 08 N / m ^2, it is found that the effect is high and preferable for abnormal transfer. The copolymer of the sulfonic acid group-containing polyester and the glycidyl group-containing acrylic of Comparative Example 9 is faster than Comparative Example 4 in which the undercoat layer 20 is not provided and Comparative Example 5 using only the sulfonic acid group-containing polyester. It was found that the transfer sensitivity at that time was high.

Comparing Examples 8 to 17 in which polyvinyl pyrrolidone was mixed with a polyster-acrylic copolymer, Comparative Example 9 being a single polyster-acrylic copolymer, and Comparative Examples 5 and 6 being a single polyvinyl pyrrolidone, mixing polyvinyl pyrrolidone It was found that the maximum reflection density was improved and the transfer sensitivity was increased.
It was also found that the transfer sensitivity was improved as the K value of the mixed polyvinyl pyrrolidone was increased.

Further, when the ratio of polyvinyl pyrrolidone to the polyester-acrylic copolymer is increased, the transfer sensitivity tends to decrease (Examples 8, 11, and 12). The mixing ratio is a polyester / acrylic copolymer and polyvinyl pyrrolidone. However, it is understood that the weight ratio is preferably 70:30 to 30:70.
Further, in Example 16, compared to the thermal transfer recording medium 1 of Example 10, the coating amount of the undercoat layer 20 is less than 0.05 g / m ² , so that the transfer sensitivity is somewhat lowered and the adhesiveness is somewhat lowered. Was confirmed. Further, in the thermal transfer recording medium 1 of Example 17, the coating amount of the undercoat layer 20 exceeds 0.30 g / m ^{2 as} compared with the thermal transfer recording medium 1 of Example 10, but the transfer sensitivity and adhesion The sex was found to be almost equivalent.
In this embodiment, the base material 10 in FIG. 1 constitutes the base material. Similarly, the heat resistant slipping layer 40 in FIG. 1 constitutes the heat resistant slipping layer. Moreover, the dye layer 30 of FIG. 1 comprises a dye layer. Further, the undercoat layer 20 in FIG. 1 constitutes the undercoat layer. Further, the thermal transfer recording medium 1 in FIG. 1 constitutes a thermal transfer recording medium.

(Effect of this embodiment)
The invention according to this embodiment has the following effects.
(1) In the thermal transfer recording medium 1 according to this embodiment, the substrate 10, the heat-resistant slip layer 40 formed on one surface of the substrate 10, and the dye formed on the other surface of the substrate 10 A thermal transfer recording medium 1 having a layer 30 and an undercoat layer 20 formed between the other surface and the dye layer 30, wherein the undercoat layer 20 has a storage elastic modulus G ′ at 100 ° C. 1.0E + 06 N / m ² or more, comprising a copolymer of a polyester having a sulfonic acid group in the side chain, an acrylic having at least one of glycidyl group and carboxyl group, and polyvinylpyrrolidone, and a heat resistant slipping layer No. 40 is characterized in that the dynamic friction coefficient μ _k for each of SiC, Si ₃ N ₄ , and SiON at 120 ° C. is 0.18 or less.

According to such a configuration, since the storage elastic modulus G ′ at 100 ° C. of the undercoat layer 20 is 1.0E + 06 N / m ² or more, abnormal transfer can be suppressed. Moreover, since the copolymer of polyester and an acryl was used, solvent resistance and dye barrier property can be improved. Further, since the dynamic friction coefficient μ _k of the heat-resistant slip layer 40 for each of SiC, Si ₃ N ₄ , and SiON at 120 ° C. is set to 0.18 or less, the thermal head of the printer can be extended. Therefore, according to such a configuration, printing can be performed more appropriately.

(2) In the thermal transfer recording medium 1 according to the present embodiment, the undercoat layer 20, the storage modulus G 100 ° C. 'is and 1.0E + 10 N / ^{m 2} or less at 1.0E + 08N / ^{m 2} or more.
According to such a configuration, the transfer sensitivity can be further improved, and wrinkles during printing can be suppressed.
(3) In the thermal transfer recording medium 1 according to this embodiment, the K value in the formula of the polyvinylpyrrolidone fixture is 30 or more and 100 or less.
According to such a configuration, it is possible to improve coating suitability while improving transfer sensitivity in printing.
(4) In the thermal transfer recording medium 1 according to this embodiment, the weight ratio of polyester in the copolymer is 20% or more and less than 40%.
According to such a configuration, it is possible to improve the print density while improving the adhesion with the substrate 10.

(5) In the thermal transfer recording medium 1 according to this embodiment, the weight ratio of the copolymer in the undercoat layer 20 is 30% or more and less than 70%.
According to such a configuration, it is possible to improve storability while improving the print density.
(6) In the thermal transfer recording medium 1 according to this embodiment, the coating amount of the undercoat layer 20 after drying is 0.10 g / m ² or more and 0.30 g / m ² or less.
According to such a configuration, it is possible to improve the cost while improving the transfer sensitivity during high-speed printing.
(7) In the thermal transfer recording medium 1 according to the present embodiment, the elongation rate of the thermal transfer recording medium 1 in the MD direction when the thermal transfer recording medium 1 is overheated while pulling a load of 5000 N / m 2 in the MD direction. The temperature T at 1% was set to 205 ° C. or higher.
According to such a configuration, generation of wrinkles during printing can be suppressed.
(8) In the thermal transfer recording medium 1 according to the present embodiment, the elongation rate of the thermal transfer recording medium 1 in the MD direction when the thermal transfer recording medium 1 is heated while being pulled with a load of 5000 N / m 2 in the MD direction. The heat resistant slipping layer 40 was used so that the temperature T at 1% was 205 ° C. or higher.
According to such a configuration, the temperature T can be set to 205 ° C. or higher relatively easily.

  The thermal transfer recording medium 1 obtained according to the present embodiment can be used in a sublimation transfer type printer, and can easily form full-color images in combination with high-speed and high-performance printers. It can be widely used for cards such as prints, ID cards, and amusement output.

10: Substrate 20: Undercoat layer 30: Dye layer 40: Heat-resistant slip layer

Claims (8)

A substrate;
A heat resistant slipping layer formed on one surface of the substrate;
A dye layer formed on the other surface of the substrate;
A thermal transfer recording medium having an undercoat layer formed between the other surface and the dye layer,
The undercoat layer has a storage elastic modulus G ′ at 100 ° C. of 1.0E + 06 N / m ² or more, a polyester having a sulfonic acid group in the side chain, and an acrylic having at least one of a glycidyl group and a carboxyl group; A copolymer of polyvinylpyrrolidone and
The thermal transfer recording medium, wherein the heat-resistant slipping layer has a dynamic friction coefficient μ _k of 0.18 or less for each of SiC, Si ₃ N ₄ , and SiON at 120 ° C. The undercoat layer, a thermal transfer recording medium according to claim 1, wherein the storage modulus G 100 ° C. 'is and 1.0E + 10N / ^{m 2} or less at 1.0E + 08N / ^{m 2} or more.   The thermal transfer recording medium according to claim 1, wherein the polyvinyl pyrrolidone has a K value in the Fickencher formula of 30 or more and less than 100. 4.   The thermal transfer recording medium according to any one of claims 1 to 3, wherein a weight ratio of the polyester in the copolymer is 20% or more and less than 40%.   The thermal transfer recording medium according to any one of claims 1 to 4, wherein the weight ratio of the copolymer in the undercoat layer is 30% or more and less than 70%. The coating amount after drying of the undercoat layer is 0.10 g / m ² or more and 0.30 g / m ² or less, according to any one of claims 1 to 5. Thermal transfer recording medium. The temperature T at which the elongation rate of the thermal transfer recording medium in the MD direction becomes 1% when the thermal transfer recording medium is heated while being pulled in the MD direction with a load of 5000 N / m ² is 205 ° C. or more. The thermal transfer recording medium according to any one of claims 1 to 6. The heat resistance such that the temperature T at which the elongation rate of the thermal transfer recording medium in the MD direction becomes 1% when the thermal transfer recording medium is heated while being pulled in the MD direction with a load of 5000 N / m ² is 205 ° C. or more. The thermal transfer recording medium according to claim 7, wherein a slipping layer is used.

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