JP2014058070A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which can effectively prevent the occurence of kick that is a phenomenon in which a dye in a dye layer is transferred to a back surface layer when the thermal transfer sheet is wound, and has the back surface layer having superior lubricating properties.SOLUTION: The thermal transfer sheet has a dye layer provided at one face of a substrate and a back surface layer provided at another face of the substrate. The back surface layer contains one of or both of sorbitan fatty acid ester and triacylglycerol having a melting point of 25°C or lower.

Description

  The present invention relates to a thermal transfer sheet.

  As a general thermal transfer sheet used in a printer, a thermal transfer sheet in which a dye layer is provided on one side of a substrate and a back layer is provided on the other side of the substrate is known. According to this thermal transfer sheet, after the transfer target such as the thermal transfer image receiving sheet and the dye layer of the thermal transfer sheet are stacked so as to face each other, the back layer and the heating device such as a thermal head are brought into contact with each other, By applying energy corresponding to image information to the heating device in such a manner as to rub on the back layer, an image can be formed on the transfer medium.

  By the way, when image formation is performed using a thermal transfer sheet having a back layer with low slipperiness, wrinkles are generated in the thermal transfer sheet during image formation, and print wrinkles are generated in the image formed accordingly. Become. Therefore, it is necessary to use a thermal transfer sheet provided with a back layer having sufficient slipperiness so as not to cause printing wrinkles in the formed image. Various proposals have been made for thermal transfer sheets focusing on the slipperiness of the back layer. For example, Patent Document 1 includes a back layer containing a phosphate ester compound and a reactive modified silicone oil as a lubricant component. Thermal transfer sheets have been proposed. Patent Document 2 proposes a thermal transfer sheet containing metal soap as a lubricant component in the back layer.

  The thermal transfer sheet is generally stored and used in a wound state. In the state where the thermal transfer sheet is wound, the dye layer and the back layer are in direct contact with each other. Therefore, when the back layer contains components that are easily dyed by the dye of the dye layer, the thermal transfer sheet A so-called kick occurs in which the dye in the dye layer moves to the back surface layer during winding. The phosphate ester, silicone oil, etc. proposed in Patent Document 1 are liquid lubricants, and are lubricant components that are particularly easily dyed by the dyes in the dye layer. Therefore, a thermal transfer sheet having a back layer containing a liquid lubricant such as phosphate ester or silicone oil has a high degree of kick generation. On the other hand, solid lubricants such as metal soaps proposed in Patent Document 2 are less likely to be dyed by dyes in the dye layer than liquid lubricants, and although the degree of kick generation is low, sufficient lubricity is exhibited. In the case where a solid lubricant is contained in the back layer, the degree of kick generation increases as in the case where a liquid lubricant is used. In other words, there is a trade-off between the effect of improving lubricity and the effect of preventing the occurrence of kicks, and if the focus is on improving the lubricity, the degree of occurrence of kicks will increase, while the occurrence of kicks will be prevented. When the main focus is on, sufficient slipperiness cannot be imparted to the back layer.

  Further, when the thermal transfer sheet having the dye layer kicked on the back layer is rolled back, a so-called back is formed in which the kicked dye re-transfers to the dye layer, causing various problems. For example, in a thermal transfer sheet in which dye layers of different colors are repeatedly provided in the surface order on the base material, when the dye kicked to the back layer backs to another dye layer containing a dye of a hue different from the dye Will cause a reduction in color development characteristics. In addition, in the integrated thermal transfer sheet in which the dye layer and the transferable protective layer are provided in the surface order on the base material, when the dye kicked to the back layer is back on the transferable protective layer, the transferable protective layer The transferability of the toner onto the transfer medium is inhibited, and the quality of the printed material after the transfer of the transferable protective layer is lowered.

  On the other hand, the metal soap proposed in Patent Document 2 has a low degree of kick generation compared to the above-described liquid lubricants such as silicone oil and phosphate ester, but is not sufficient in terms of prevention of kick generation. . There is also room for improvement in terms of lubricity.

JP 2008-188902 A JP 2004-90594 A

  The present invention has been made in view of such a situation, and when the thermal transfer sheet is wound up, it is possible to effectively prevent the occurrence of a kick in which the dye in the dye layer moves to the back layer, and the back layer is slipped. The main object is to provide a thermal transfer sheet having excellent properties.

  The present invention for solving the above problems is a thermal transfer sheet in which a dye layer is provided on one side of a substrate and a back layer is provided on the other side of the substrate, the back layer comprising sorbitan One or both of a fatty acid ester and a triacylglycerol having a melting point of 25 ° C. or less are contained.

  In addition, the content of either or both of the sorbitan fatty acid ester and the triacylglycerol having a melting point of 25 ° C. or less relative to the total solid content of the back layer may be 2% by mass or more and 20% by mass or less. The back layer may further contain a solid lubricant having a melting point of 80 ° C. or higher, and the content of the solid lubricant with respect to the total solid content of the back layer may be 1% by mass or more and 15% by mass or less. .

  According to the present invention, it is possible to effectively prevent the occurrence of a kick in which the dye of the dye layer shifts to the back layer when the thermal transfer sheet is wound up while providing sufficient slip to the back layer.

It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention.

  Hereinafter, the thermal transfer sheet of the present invention will be specifically described with reference to the drawings. 1 to 3 are schematic cross-sectional views showing an example of the thermal transfer sheet of the present invention.

  As shown in FIGS. 1 to 3, the thermal transfer sheet 10 of the present invention has a configuration in which a dye layer 3 is provided on one surface of a substrate 1 and a back layer 5 is provided on the other surface of the substrate 1. I'm taking it. The thermal transfer sheet 10 of the present invention is characterized in that the back layer 5 contains one or both of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower. The present invention is not limited to any other requirement as long as it has this requirement. For example, as shown in FIG. 2, a dye primer layer 7 may be provided between the substrate 1 and the dye layer 3, and a release layer (not shown) is provided between the substrate 1 and the dye layer 3. It may be done. A back primer layer (not shown) may be provided between the base material 1 and the back layer 5. Moreover, as shown in FIG. 3, the dye layer 3 may have a configuration in which a plurality of dye layers (3Y, 3M, 3C) having different hues are provided in the surface order. In addition, the dye primer layer 7, the release layer, and the back primer layer are arbitrary configurations in the thermal transfer sheet 10 of the present invention. Hereinafter, each configuration of the thermal transfer sheet 10 will be specifically described.

(Base material)
The substrate 1 is an essential component in the thermal transfer sheet 10 of the present invention, and is provided to hold a dye layer 3 and a back layer 5 described later. The material of the substrate 1 is not particularly limited, but it is desirable that the material has mechanical characteristics that can withstand heat applied by the thermal head when the dye layer 3 is transferred onto the transfer target and does not hinder handling. Examples of such base materials include polyesters such as polyethylene terephthalate, polyarylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivatives, polyethylene, ethylene / vinyl acetate copolymer, polypropylene, polystyrene, acrylic, and polyvinyl chloride. , Polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene / perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexafluoro Various plastic fills such as propylene, polychlorotrifluoroethylene, and polyvinylidene fluoride Or it can be given a seat. Moreover, the thickness of the base material 1 can be appropriately set according to the material so that the strength and heat resistance are appropriate, and is generally about 2 to 100 μm, preferably 1 to 10 μm.

(Back layer)
As shown in the drawing, a back layer 5 that is an essential component of the thermal transfer sheet 10 of the present invention is formed on the other surface of the substrate 1 (the lower surface of the substrate 1 in the case shown in FIGS. 1 to 3). Yes.

  The back layer 5 contains a lubricant component and a binder, and the lubricant component contains one or both of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower.

<< Lubricant ingredient >>
The back layer 5 contains one or both of sorbitan fatty acid ester as a lubricant component and triacylglycerol having a melting point of 25 ° C. or lower. Sorbitan fatty acid ester, triacylglycerol having a melting point of 25 ° C. or lower has a feature that it is difficult to be dyed by dyes in a dye layer as compared with conventionally known solid lubricants such as metal soaps as well as conventionally known liquid lubricants. Therefore, according to the back layer 5 containing sorbitan fatty acid ester and / or triacylglycerol having a melting point of 25 ° C. or less, the thermal transfer sheet 10 of the present invention is wound so that the dye layer 3 and the back layer 5 face each other. When taken off, it is possible to effectively prevent the occurrence of a kick in which the dye of the dye layer 3 moves to the back layer 5.

  Furthermore, sorbitan fatty acid ester, triacylglycerol having a melting point of 25 ° C. or less is excellent in lubricity, so that sufficient lubricity can be imparted to the back layer 5 to prevent generation of print wrinkles during image formation. can do.

<Sorbitan fatty acid ester>
The sorbitan fatty acid ester is an ester of sorbitan and a fatty acid represented by RCOOH (general formula (1)), and the sorbitan fatty acid ester includes a linear or branched fatty acid residue. In addition, the fatty acid residue said in this specification means "RCOO" in the said General formula (1). There is no particular limitation on the fatty acid residue contained in the sorbitan fatty acid ester. For example, lauric acid residue, palmitic acid residue, stearic acid residue, isostearic acid residue, oleic acid residue, caprylic acid residue, myristic acid residue Group, behenic acid residue and the like.

  Specific examples of sorbitan fatty acid esters containing these fatty acid residues include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan sesquistearate, sorbitan dilaurate. Sorbitan dipalmitate, sorbitan distearate, sorbitan dioleate, sorbitan trilaurate, sorbitan tripalmitate, sorbitan tristearate, sorbitan trioleate and the like can be presented. These sorbitan fatty acid esters may be used alone or in combination of two or more.

  As described above, the fatty acid residue contained in the sorbitan fatty acid ester is not particularly limited, but the fatty acid residue contained in the sorbitan fatty acid ester includes a fatty acid residue having a shorter carbon chain length as the carbon chain length is longer. Compared with fatty acid esters, it has a property that it is harder to be dyed by the dye of the dye layer and is excellent in lubricity. Accordingly, it is preferable that the sorbitan fatty acid ester contains a fatty acid residue having a long carbon chain length. Specifically, the sorbitan fatty acid ester may contain a fatty acid residue having a carbon chain length of 18 or more. preferable. More specifically, a sorbitan fatty acid ester containing a stearic acid residue, an oleic acid residue or the like is preferable.

  When the sorbitan fatty acid ester is other than sorbitan monofatty acid ester, the fatty acid residues contained in the sorbitan fatty acid ester may be the same or different. When fatty acid residues are different, at least one fatty acid residue is preferably a fatty acid residue having a carbon chain length of 18 or more, and all fatty acid residues are fatty acids having a carbon chain length of 18 or more. A residue is particularly preferred. In the present specification, when the fatty acid residue having a carbon chain length of 18 or more is included, the carbon chain of at least one fatty acid residue among one or two or more fatty acid residues contained in the sorbitan fatty acid ester It means that the length is 18 or more.

<Triacylglycerol>
The back surface layer 5 contains triacylglycerol represented by the following general formula (2) instead of or together with the sorbitan fatty acid ester described above. In the general formula (2), “R ₁ COO”, “R ₂ COO”, and “R ₃ COO” are linear or branched fatty acid residues, respectively. The fatty acid residues (“R ₁ COO”, “R ₂ COO”, “R ₃ COO”) may be the same or different. In the present invention, the melting point of triacylglycerol is regulated to 25 ° C. or less. The melting point of triacylglycerol in the present invention is a melting point measured according to JIS K 0064 (1992). The same applies to the melting point of the solid lubricant described later.

  The triacylglycerol having a melting point of 25 ° C. or lower has the property that it is difficult to be dyed by the dye of the dye layer, and that the back layer 5 can be given good lubricity, like the sorbitan fatty acid ester described above. Therefore, according to the back surface layer 5 containing the triacylglycerol having a melting point of 25 ° C. or less, it is possible to prevent the occurrence of kick and the generation of wrinkles during image formation. In the case where monoacylglycerol or diacylglycerol alone is included in the back layer as glycerin fatty acid ester without including sorbitan fatty acid ester or triacylglycerol having a melting point of 25 ° C. or lower, occurrence of kick In addition, the occurrence of printing wrinkles cannot be effectively prevented. In addition, when triacylglycerol having a melting point exceeding 25 ° C. is contained in the back layer 5 instead of triacylglycerol having a melting point of 25 ° C. or lower, generation of print wrinkles cannot be effectively prevented.

There is no particular limitation on the fatty acid residue (“R ₁ COO”, “R ₂ COO”, “R ₃ COO”) contained in triacylglycerol having a melting point of 25 ° C. or lower. Examples thereof include oleic acid residues and caprylic acid residues which are residues. Triacylglycerol having a melting point of 25 ° C. or less may be used alone or in combination of two or more. In addition, triacylglycerol containing a fatty acid residue of a fatty acid having a melting point of 25 ° C. or lower, for example, tri (caprylic acid / capric acid) glycerol can be used.

  Specific compounds of these triacylglycerols containing these fatty acid residues and having a melting point of 25 ° C. or lower include, for example, glycerol trioleate, glycerol tricaprylate, tri (oleic acid / palmitic acid / stearic acid) glycerol, tri ( And caprylic acid / capric acid) glycerol.

  Triacylglycerol having a melting point of 25 ° C. or lower has a low HLB value because all three hydroxyl groups of glycerin are esterified. It is presumed that the kick prevention effect improves as the HLB value decreases. Therefore, according to the triacylglycerol having a melting point of 25 ° C. or lower in which all three hydroxyl groups of glycerin are esterified, the carbon chain length of the fatty acid residue contained in the triacylglycerol having a melting point of 25 ° C. or lower is set. Regardless, it is possible to achieve a sufficient kick prevention effect while providing the back layer 5 with lubricity. For the purpose of further improving the prevention of kick generation, it is preferable that the triacylglycerol having a melting point of 25 ° C. or lower contains a fatty acid residue having a carbon chain length of 18 or more. In other words, the triacylglycerol having a melting point of 25 ° C. or less preferably contains a fatty acid residue having a carbon chain length of 18 or more, such as an oleic acid residue. Moreover, it is preferable that all the fatty acid residues contained in triacylglycerol are fatty acid residues having a carbon chain length of 18 or more.

  There is no particular limitation on the content of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower with respect to the total solid content of the back layer 5, but sorbitan fatty acid ester, triacylglycerol having a melting point of 25 ° C. or lower, or the total mass thereof. However, when it is less than 2 mass% with respect to the total solid content of the back layer 5, the slipperiness of the back layer 5 tends to decrease. On the other hand, if it exceeds 20% by mass, the effect of preventing kick generation and the effect of further improving the lubricity of the back layer 5 cannot be expected, and the content of the binder is reduced correspondingly. Tend to decrease. Therefore, in consideration of this point, the sorbitan fatty acid ester, the triacylglycerol having a melting point of 25 ° C. or less, or the total mass thereof is in the range of 2% by mass or more and 20% by mass or less with respect to the total solid content of the back layer 5. It is preferable that

  Also, sorbitan fatty acid ester and / or sorbitan fatty acid ester containing a fatty acid residue having a carbon chain length of 18 or more and / or fatty acid having a carbon chain length of 18 or more with respect to the total mass of triacylglycerol having a melting point of 25 ° C. or lower. The content of triacylglycerol having a melting point including a residue of 25 ° C. or less is preferably 80% by mass or more. By setting the content of sorbitan fatty acid ester containing a fatty acid residue having a carbon chain length of 18 or more and / or triacylglycerol having a melting point of 25 ° C. or less containing a fatty acid residue having a carbon chain length of 18 or more in this range. Further, the effect of preventing the occurrence of kick and the effect of improving the slipperiness of the back layer 5 can be further enhanced.

  Further, the back layer 5 preferably contains a solid lubricant having a melting point of 80 ° C. or higher together with sorbitan fatty acid ester and / or triacylglycerol having a melting point of 25 ° C. or lower. By incorporating a solid lubricant having a melting point of 80 ° C. or higher in the back surface layer 5, synergy of sorbitan fatty acid ester and / or triacylglycerol having a melting point of 25 ° C. or lower and a solid lubricant having a melting point of 80 ° C. or higher. Due to the effect, it is possible to further improve the lubricity of the back layer 5 from the vicinity of the melting point of the solid lubricant.

  As the solid lubricant having a melting point of 80 ° C. or higher, metal soap, fatty acid amide which is a fatty acid derivative, or the like is preferable. These metal soaps include, for example, polyvalent metal salts of alkyl phosphates, polyvalent metal salts of fatty acids, metal salts of alkyl carboxylic acids, and more specifically, zinc stearyl phosphate, zinc stearate, etc. Can be mentioned. Examples of the fatty acid amide include ethylene bisoleic acid amide, methylene bis stearic acid amide, and stearic acid amide.

  The melting point of the solid lubricant only needs to satisfy the condition of 80 ° C. or higher, and a melting point corresponding to the desired level of lubricity may be selected as appropriate.

  Although these solid lubricants can improve the lubricity of the back layer 5, they are more easily dyed by the dye of the dye layer than the sorbitan fatty acid ester and the triacylglycerol having a melting point of 25 ° C. or less. When the content of the solid lubricant having a melting point of 80 ° C. or higher with respect to the total solid content of 5 exceeds 15% by mass, the back layer 5 tends to be dyed by the dye of the dye layer, and the effect of preventing the occurrence of kick tends to decrease. It is in. Therefore, in consideration of this point, the content of the solid lubricant having a melting point of 80 ° C. or higher with respect to the total solid content of the back layer 5 is preferably 15% by mass or less, and from the viewpoint of further improving the lubricity. Is preferably 1% by mass or more.

  Moreover, the back surface layer 5 may contain a lubricant component other than this within the range not impeding the gist of the present invention. Examples of other lubricant components include phosphate esters, graphite powder, fluorine-based graft polymers, silicone oils, silicone-based graft polymers, acrylic silicone graft polymers, silicone polymers such as acrylic siloxane and aryl siloxane, and polyethylene. it can. These other lubricant components are preferably 5% by mass or less based on the total solid content of the back layer 5.

<< Binder >>
The back layer 5 contains a binder together with the sorbitan fatty acid ester as a lubricant component and / or triacylglycerol having a melting point of 25 ° C. or lower.

  The binder contained in the back layer 5 is not particularly limited, and examples thereof include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyethylene resins, and polypropylene resins. Polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyether resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, polyacrylamide resin, polyvinyl chloride resin, polyvinyl butyral resin, polyvinyl aceto Thermoplastic resins such as polyvinyl acetal resins such as acetal resins, silicone modified products thereof, and the like can be used.

  The binder may be a curable binder. According to the back layer 5 containing a curable binder, the coating strength and heat resistance can be improved. As a curing agent for making a curable binder, polyisocyanate is suitable, and it is particularly desirable to use an adduct body of aromatic isocyanate. As the aromatic polyisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, Examples include p-phenylene diisocyanate, trans-cyclohexane-1,4-diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, and tris (isocyanatophenyl) thiophosphate, particularly 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Or, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is preferable.

  There is no limitation in particular about content of a binder, According to content of the sorbitan fatty acid ester which is an essential component mentioned above, and the triacylglycerol whose melting | fusing point is 25 degrees C or less, it can determine suitably. Preferably, it is the range of 40 mass% or more and 90 mass% or less with respect to the solid content total amount of the back surface layer 5.

The method for forming the back layer 5 is not particularly limited, and the sorbitan fatty acid ester described above and / or triacylglycerol having a melting point of 25 ° C. or less, a binder, other components added as necessary, etc. Known means such as a gravure printing method, a screen printing method, a reverse roll coating printing method using a gravure plate on the surface of the substrate 1 opposite to the dye layer 3 of the coating liquid dispersed or dissolved in a solvent Can be formed by coating and drying. The coating amount of the back layer 5, from the viewpoint of improvement of such as heat resistance, it is preferable that drying after coating weight of 3 g / m ² or less, and more preferably to 0.1-2 g / m ² .

(Back primer layer)
Further, a back primer layer (not shown) for improving the adhesion between the base material 1 and the back layer 5 may be provided between the base material 1 and the back layer 5. Examples of the material for the back primer layer include those showing adhesiveness such as polyester resin and acrylic resin.

(Dye layer)
As shown in the drawing, a dye layer 3 that is an essential component of the thermal transfer sheet 10 of the present invention is formed on one surface of the substrate 1 (the upper surface of the substrate 1 in the case shown in FIGS. 1 to 3). Yes. The thermal transfer sheet 10 of the present invention is characterized in that the back layer 5 contains the sorbitan fatty acid ester described above and / or a triacylglycerol having a melting point of 25 ° C. or less. There is no limitation on

  The dye layer 3 contains a dye binder and a dye. The dye layer 3 may be formed as a single color layer selected as appropriate when the desired image is monochromatic, or as shown in FIG. 3 when the desired image is a full color image. A plurality of dye layers 3Y, 3M, and 3C including dyes having different hues, such as yellow dye, magenta dye, cyan dye, and black dye as necessary, are repeatedly formed on the same surface of the same substrate in the surface order. Also good. In the thermal transfer sheet including a plurality of dye layers 3 containing dyes having different hues, the dye kicked to the back layer, for example, the yellow dye kicked to the back layer is the kicked dye when the thermal transfer sheet is rolled back. When backing to another dye layer having a different hue, for example, a cyan dye layer, color development characteristics may be caused when an image is formed using the cyan dye layer, or image quality may be reduced when an image is formed using the cyan dye layer. In the present invention, since the occurrence of kick is prevented in the back layer 5 as described above, the present invention is a case where the thermal transfer sheet is provided with a plurality of dye layers having different hues. In addition, the effect of preventing the deterioration of the image quality can be achieved.

  When the thermal transfer sheet 10 of the present invention is a sublimation type thermal transfer sheet, the dye layer 3 contains a sublimable dye. When the thermal transfer sheet 10 of the present invention is a thermal melt type thermal transfer sheet, a hot melt ink or the like is contained. included.

  As the sublimable dye, those having a sufficient color density and not discolored by light, heat, temperature, etc. are preferable. For example, diarylmethane dyes, triarylmethane dyes, thiazole dyes, merocyanine dyes, pyrazolones Dyes, methine dyes, indoaniline dyes, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, imidazoazomethine, pyridone azomethine and other azomethine dyes, xanthene dyes, oxazine dyes, dicyanostyrene, tricyanostyrene and other cyano Styrene dyes, thiazine dyes, azine dyes, acridine dyes, benzene azo dyes, pyridone azo, thiophenazo, isothiazole azo, pyrrole azo, pyrazole azo, imidazole azo, thiadiazole azo, triazole azo Azo dye of the disazo, etc., spiropyran dyes, India Linos Piropi run dyes, fluoran dye, rhodamine lactam-based dyes, naphthoquinone dyes, anthraquinone dyes, quinophthalone dyes, and the like. Specifically, red dyes such as MSRedG (manufactured by Mitsui Toatsu Chemical Co., Ltd.), Macrolex Red Violet R (manufactured by Bayer), CeresRed 7B (manufactured by Bayer), Samalon Red F3BS (manufactured by Mitsubishi Chemical), and holon brilliant yellow Yellow dyes such as 6GL (manufactured by Clariant), PTY-52 (manufactured by Mitsubishi Kasei), Macrolex Yellow 6G (manufactured by Bayer), Kayaset Blue 714 (manufactured by Nippon Kayaku Co., Ltd.), Waxoline Blue AP-FW ( ICI), Holon Brilliant Blue SR (Sand), MS Blue 100 (Mitsui Toatsu Chemical), C.I. I. Blue dyes such as Solvent Blue 22 are listed.

  As the dye binder for supporting the dye, generally, a binder having heat resistance and having an appropriate affinity with the dye can be used. Examples of the dye binder include cellulose resins such as nitrocellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and butyric acid cellulose; polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, Examples thereof include vinyl resins such as polyvinyl pyrrolidone; acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide; polyurethane resins; polyamide resins; polyester resins;

  The sublimable dye is preferably 50% by mass or more and 350% by mass, and more preferably 80% by mass or more and 300% by mass with respect to the total solid content of the dye binder of the dye layer 3. When the content of the sublimation dye is less than the above range, the printing density may be lowered, and when it exceeds the above range, the storage stability and the like may be deteriorated.

  Further, the dye layer 3 of the sublimation type thermal transfer sheet 10 may contain additives such as a release agent, inorganic fine particles, and organic fine particles, if desired. Examples of the release agent include silicone oil and phosphate ester, examples of the inorganic fine particles include carbon black, aluminum, and molybdenum disulfide. Examples of the organic fine particles include polyethylene wax.

  The heat-meltable ink contained in the dye layer 3 of the heat-melting type thermal transfer sheet 10 can be appropriately selected from known organic or inorganic pigments or dyes, and has, for example, a sufficient color density. Those which do not discolor or fade due to light, heat, or the like are preferable. The color of the hot-melt ink is not limited to cyan, magenta, yellow, and black, and various colorants can be used.

  Examples of the dye binder contained in the dye layer 3 of the heat melting type thermal transfer sheet 10 include, for example, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, and chloride. Vinyl resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, acrylic resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetyl cellulose, nitrocellulose, polyvinyl acetate, poly Examples include isobutylene, ethyl cellulose, and polyacetal.

  The hot-melt dye layer 3 includes microcrystalline wax, carnauba wax, paraffin wax, and the like. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide and other waxes Ingredients may be included.

  The formation method of the dye layer 3 is not particularly limited, and a gravure printing method is performed by dispersing or dissolving the dye, the dye binder, and any components added as necessary in an appropriate solvent. It is formed by applying and drying on the opposite surface of the back layer 5 of the substrate 1 by a conventionally known coating means such as a reverse roll coating method using a gravure plate, a roll coater or a bar coater. Can do.

  Although there is no limitation in particular about the thickness of the dye layer 3, It is preferable that it is about 0.3 micrometer-1.5 micrometers in the thickness at the time of drying.

(Dye primer layer)
When the thermal transfer sheet of the present invention is a sublimation type thermal transfer sheet, a dye primer layer 7 is preferably provided between the substrate 1 and the dye layer 3 as shown in FIG. By providing the dye primer layer, the adhesion between the substrate 1 and the dye layer 3 can be improved, and the dye layer 3 can be prevented from being abnormally transferred during image formation.

  The resins constituting the dye primer layer include polyester resins, polyvinyl pyrrolidone resins, polyvinyl alcohol resins, hydroxyethyl cellulose, polyacrylate resins, polyvinyl acetate resins, polyurethane resins, styrene acrylate resins, polyacrylamide resins. Examples thereof include resins, polyamide resins, polyether resins, polystyrene resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, and the like.

  The dye primer layer can also be composed of colloidal inorganic pigment ultrafine particles. This not only prevents abnormal transfer of the dye layer 3 to the thermal transfer image receiving sheet at the time of thermal transfer, but also prevents migration of the dye from the dye layer 3 to the dye primer layer at the time of image formation, to the receiving layer side of the thermal transfer image receiving sheet. Dye diffusion can be performed effectively and the print density can be increased.

  As the colloidal inorganic pigment ultrafine particles, conventionally known compounds can be used. For example, silica (colloidal silica), alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or hydrate, suspect boehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, magnesium oxide, oxidation Examples include titanium. In particular, colloidal silica and alumina sol are preferably used. These colloidal inorganic pigment ultrafine particles have a primary average particle size of 100 nm or less, preferably 50 nm or less.

For the dye primer layer, the resin exemplified above and the coating solution for the dye primer layer in which the colloidal inorganic pigment ultrafine particles are dissolved or dispersed in an appropriate solvent are used as a gravure coating method, a roll coating method, a screen printing method, and a gravure plate. It can be formed by coating and drying by a conventionally known forming means such as the reverse roll coating method used. The coating amount of the dye primer layer coating solution is preferably about 0.02 to 1.0 g / m ² .

  On the other hand, when the thermal transfer sheet of the present invention is a thermal melting type thermal transfer sheet, a release layer is preferably provided between the substrate 1 and the dye layer 3. Examples of the resin forming the release layer include waxes, silicone wax, silicone resin, silicone-modified resin, fluorine resin, fluorine-modified resin, polyvinyl alcohol, acrylic resin, heat-crosslinkable epoxy-amino resin, and heat-crosslinkable alkyd. -Amino resin etc. are mentioned. Further, the release layer may be composed of one kind of resin or may be composed of two or more kinds of resins. The release layer may be formed by using a cross-linking agent such as an isocyanate compound, a catalyst such as a tin-based catalyst, and an aluminum-based catalyst in addition to the releasable resin. The thickness of the release layer is generally about 0.5 to 5 μm. The release layer is formed by dissolving or dispersing the resin in a suitable solvent to prepare a release layer coating solution, which is then applied to the substrate 1 by a gravure printing method, a screen printing method or a gravure plate. It can be formed by coating and drying by a conventionally known means such as a reverse coating method using a bismuth.

  The thermal transfer sheet 10 of the present invention has been specifically described above, but various modifications can be made without departing from the spirit of the present invention. For example, in the configuration shown in FIGS. 1 to 3, an integrated thermal transfer sheet in which the dye layer 3 and a transferable protective layer (not shown) are provided in the surface order on the same surface of the substrate 1 may be used. A release layer can also be provided between the substrate 1 and the transferable protective layer.

  Next, an Example is given and this invention is demonstrated further more concretely. Hereinafter, unless otherwise specified, “part” and “%” are based on mass. Further, unless otherwise specified, “parts” and “%” indicate solid content values.

Example 1
A 4.5 μm thick polyethylene terephthalate film having a thickness of 4.5 μm was used as the base material, and the back layer coating solution 1 having the following composition was applied to one side of the base material, and the coating amount upon drying was 1.0 g / m It was coated using a bar coater so as to be ^2, and dried at 80 ° C. for 1 minute to form a back layer. Also, apply the coating solution for the dye layer having the following composition on the other side of the substrate (the surface that is easily treated) using a bar coater so that the coating amount when dried is 0.6 g / m ^2. The thermal transfer sheet of Example 1 was obtained by forming an ink dye layer.

<Back layer coating liquid 1>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Sorbitan monolaurate (HLB value: 8.6) 10.0 parts (Rheidol SP-L10 Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

<Coating liquid for dye layer>
・ Disperse dye (disperse thread 60) 1.5 parts ・ Disperse dye (dispers violet 26) 2.0 parts ・ Polyvinyl acetal resin 4.5 parts (Eslex KS-5 Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Toluene 45.0 parts ・ Methyl ethyl ketone 45.0 parts

(Example 2)
A thermal transfer sheet of Example 2 was obtained in the same manner as in Example 1 except that instead of the back layer coating solution 1, a back layer coating solution 2 having the following composition was used.

<Back layer coating liquid 2>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Sorbitan monopalmitate (HLB value: 6.7) 10.0 parts (Rheidol SP-P10 Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 3)
A thermal transfer sheet of Example 3 was obtained in the same manner as in Example 1 except that instead of the back layer coating solution 1, a back layer coating solution 3 having the following composition was used.

<Back layer coating liquid 3>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
-Sorbitan monostearate (HLB value: 4.7) 10.0 parts (Rheidol SP-S10V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

Example 4
A thermal transfer sheet of Example 4 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 4 having the following composition was used.

<Back layer coating liquid 4>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Sorbitan monooleate (HLB value: 4.3) 10.0 parts (Rheodor SP-O10V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 5)
A thermal transfer sheet of Example 5 was obtained in the same manner as Example 1 except that the back layer coating solution 5 having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid 5>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Sorbitan sesquioleate (HLB value: 3.7) 10.0 parts (Rheodor AO-15V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 6)
A thermal transfer sheet of Example 6 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 6 having the following composition was used.

<Back layer coating liquid 6>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
-Sorbitan tristearate (HLB value: 2.1) 10.0 parts (Rheidol SP-S30V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 7)
A thermal transfer sheet of Example 7 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 7 having the following composition was used.

<Back layer coating liquid 7>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Sorbitan trioleate (HLB value: 1.8) 10.0 parts (Rheodor SP-O30V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 8)
A thermal transfer sheet of Example 8 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 8 having the following composition was used.

<Back layer coating liquid 8>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl trioleate (melting point <25 ° C.) 10.0 parts (Triolein Tokyo Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

Example 9
A thermal transfer sheet of Example 9 was obtained in the same manner as in Example 1 except that instead of the back layer coating solution 1, a back layer coating solution 9 having the following composition was used.

<Back layer coating liquid 9>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
Tri (oleic acid / palmitic acid / stearic acid) glycerol (95/4/1) (melting point <25 ° C.) 10.0 parts (Actor LO-1 Riken Vitamin Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 10)
A thermal transfer sheet of Example 10 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 10 having the following composition was used.

<Back layer coating liquid 10>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
Tri (caprylic acid / capric acid) glyceryl (melting point <25 ° C.) 10.0 parts (NIKKOL Triester F-180 Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 11)
A thermal transfer sheet of Example 11 was obtained in the same manner as Example 1 except that the back layer coating solution 11 having the following composition was used instead of the back layer coating solution 1.

<Back surface layer coating solution 11>
-Polyvinyl acetal resin 53.8 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ 26.2 parts of polyisocyanate (Bernock D750 DIC Corporation)
・ Sorbitan monooleate (HLB value: 4.3) 10.0 parts (Rheodor SP-O10V Kao Corporation)
・ Glyceryl trioleate 5.0 parts (Triolein Tokyo Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 12)
A thermal transfer sheet of Example 12 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 12 having the following composition was used.

<Back layer coating liquid 12>
-Polyvinyl acetal resin 53.8 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ 26.2 parts of polyisocyanate (Bernock D750 DIC Corporation)
・ Sorbitan monooleate (HLB value: 4.3) 10.0 parts (Rheodor SP-O10V Kao Corporation)
・ Zinc stearyl phosphate (melting point: 230 ° C.) 5.0 parts (LBT-1830 purification, Sakai Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 13)
A thermal transfer sheet of Example 13 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 13 having the following composition was used.

<Back layer coating liquid 13>
-Polyvinyl acetal resin 53.8 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ 26.2 parts of polyisocyanate (Bernock D750 DIC Corporation)
・ Sorbitan monooleate (HLB value: 4.3) 10.0 parts (Rheodor SP-O10V Kao Corporation)
・ Stearic acid amide (melting point: 101 ° C.) 5.0 parts (Amide AP-1 Nippon Kasei Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 14)
A thermal transfer sheet of Example 14 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 14 having the following composition was used.

<Back layer coating liquid 14>
-Polyvinyl acetal resin 53.8 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ 26.2 parts of polyisocyanate (Bernock D750 DIC Corporation)
Tri (caprylic acid / capric acid) glyceryl (melting point <25 ° C.) 10.0 parts (NIKKOL Triester F-180 Nikko Chemicals Co., Ltd.)
・ Zinc stearyl phosphate (melting point: 230 ° C.) 5.0 parts (LBT-1830 purification, Sakai Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 15)
A thermal transfer sheet of Example 15 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 15 having the following composition was used.

<Back layer coating solution 15>
-Polyvinyl acetal resin 53.8 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ 26.2 parts of polyisocyanate (Bernock D750 DIC Corporation)
Tri (caprylic acid / capric acid) glyceryl (melting point <25 ° C.) 10.0 parts (NIKKOL Triester F-180 Nikko Chemicals Co., Ltd.)
・ Stearic acid amide (melting point: 101 ° C.) 5.0 parts (Amide AP-1 Nippon Kasei Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 16)
A thermal transfer sheet of Example 16 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 16 having the following composition was used.

<Back layer coating liquid 16>
・ Polyvinyl acetal resin 50.4 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ Polyisocyanate 24.6 parts (Bernock D750 DIC Corporation)
・ Sorbitan trioleate (HLB value: 1.8) 20.0 parts (Rheodor SP-O30V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 17)
A thermal transfer sheet of Example 17 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 17 having the following composition was used.

<Back layer coating liquid 17>
・ Polyvinyl acetal resin 50.4 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
・ Polyisocyanate 24.6 parts (Bernock D750 DIC Corporation)
・ Glyceryl trioleate (melting point <25 ° C.) 20.0 parts (Triolein Tokyo Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 18)
A thermal transfer sheet of Example 18 was obtained in the same manner as in Example 1 except that instead of the back layer coating liquid 1, a back layer coating liquid 18 having the following composition was used.

<Back layer coating liquid 18>
・ 47.1 parts of polyvinyl acetal resin (SREC KS-1 Sekisui Chemical Co., Ltd.)
・ Polyisocyanate 22.9 parts (Bernock D750 DIC Corporation)
・ Sorbitan trioleate (HLB value: 1.8) 25.0 parts (Rheodor SP-O30V Kao Corporation)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that the back layer coating solution A having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid A>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl dioleate 10.0 parts (NIKKOL DGO-80 Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that the back layer coating solution B having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid B>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl distearate 10.0 parts (NIKKOL DGS-80 Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 3)
A thermal transfer sheet of Comparative Example 3 was obtained in the same manner as Example 1 except that the back layer coating solution C having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid C>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl monooleate 10.0 parts (NIKKOL MGO Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 4)
A thermal transfer sheet of Comparative Example 4 was obtained in the same manner as Example 1 except that the back layer coating solution D having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid D>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl monostearate 10.0 parts (NIKKOL MGS-A Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 5)
A thermal transfer sheet of Comparative Example 5 was obtained in the same manner as Example 1 except that the back layer coating solution E having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid E>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Phosphate ester 10.0 parts (Pricesurf A-208F Daiichi Kogyo Seiyaku Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 6)
A thermal transfer sheet of Comparative Example 6 was obtained in the same manner as in Example 1 except that the back layer coating solution F having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid F>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Butyl stearate 10.0 parts (NIKKOL BS Nikko Chemicals Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Comparative Example 7)
A thermal transfer sheet of Comparative Example 7 was obtained in the same manner as in Example 1 except that the back layer coating solution G having the following composition was used instead of the back layer coating solution 1.

<Back layer coating liquid G>
-Polyvinyl acetal resin 56.3 parts (ESREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate 28.7 parts (Bernock D750 DIC Corporation)
・ Glyceryl tristearate (melting point> 25 ° C.) 10.0 parts (Tristearin Tokyo Chemical Industry Co., Ltd.)
-Talc 5.0 parts (MICRO ACE P-3 Nippon Talc Industry Co., Ltd.)
・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Evaluation of printing wrinkles)
Sublimation type thermal transfer printer (manufactured by ALTECH ADS) Model: CW-01) Media set CW-MS46 Y region, M region, C region, each of the thermal transfer sheet of each example and comparative example, respectively, After leaving the printer and the media set genuine thermal transfer image receiving sheet in a low temperature and low humidity environment (5 ° C, 20%) for 3 hours, (1) black solid image, (2) right black image (left (White), (3) left black image (right white), (4) middle black image (left and right white) were printed 5 sheets each (20 sheets in total), and the print wrinkle was evaluated based on the following evaluation criteria. . The black image is an image formed with (255/255 gradation), and the white image is an image formed with (0/255 gradation). The evaluation results are shown in Table 1.

"Evaluation criteria 1"
... No wrinkle generated in all images ((1) to (4))... Wrinkle generated in any one of the images (1) to (4). Wrinkles occur in 2 to 3 types of images among (1) to (4).
X: Wrinkles occur in all the images (1) to (4).

"Evaluation criteria 2"
◎ ・ ・ ・ No print wrinkles.
○: Fine wrinkles occur at the edge of the printed material.
X: In addition to the fine wrinkles at the edges of the printed matter, large and noticeable wrinkles occur.

(Kick evaluation)
The back layer and the dye layer of the thermal transfer sheet of each example and comparative example were opposed to ^each other, applied with a load of 15 kg / cm ² , stored for 96 hours in an environment of 40 ° C. and 90% humidity, and the dye layer on the back layer side. The dye was transferred (kicked). The hues of the back and front layers before and after facing were measured using Gretag Spectrolino (D65 light source, viewing angle 2 °) manufactured by Gretag, and the color difference (ΔE ^* ) was calculated by the following formula and evaluated based on the following criteria. The evaluation results are also shown in Table 1.
ΔE ^* = ((difference between L ^* values before and after facing) ² + (difference between a ^* values before and after facing) ² + (difference between b ^* values before and after facing) ² ) ^1/2

"Evaluation criteria"
◎ ・ ・ ・ Color difference ΔE ^* is less than 2.5 ○ ・ ・ ・ Color difference ΔE ^* is 2.5 or more and less than 3.0 Δ ・ ・ ・ Color difference ΔE ^* is 3.0 or more and less than 5.0 × ・ ・ ・ Color difference ΔE ^* Is 5.0 or more

  As is clear from Table 1, according to the thermal transfer sheet of the example in which the back layer contains one or both of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower, Good results were obtained for both kick evaluations. On the other hand, in the thermal transfer sheet of the comparative example in which the back layer does not contain any of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower, the evaluation of either one of the printing wrinkles and kicks, or both is given in the examples. The result was inferior. Also from this, the superiority of the present invention became clear.

DESCRIPTION OF SYMBOLS 1 ... Base material 3 ... Dye layer 5 ... Back layer 7 ... Dye primer layer 10 ... Thermal transfer sheet

Claims (3)

A thermal transfer sheet provided with a dye layer on one side of a substrate and a back layer on the other side of the substrate,
The thermal transfer sheet, wherein the back layer contains one or both of sorbitan fatty acid ester and triacylglycerol having a melting point of 25 ° C. or lower.   The content of either or both of the sorbitan fatty acid ester and the triacylglycerol having a melting point of 25 ° C. or lower relative to the total solid content of the back layer is 2% by mass or more and 20% by mass or less. Item 2. The thermal transfer sheet according to Item 1. The back layer further contains a solid lubricant having a melting point of 80 ° C. or higher;
The thermal transfer sheet according to claim 1 or 2, wherein the content of the solid lubricant with respect to the total solid content of the back layer is 1% by mass or more and 15% by mass or less.

Images