JP5387233B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet that improves the lubricity between a thermal head and a back layer and prevents color bleeding.

  In recent years, higher speed printers require faster thermal heads and higher resolution, and the thermal energy applied to the thermal heads continues to increase. As a result, the temperature around the printer heat generating part during image formation (temperature around the thermal head) tends to continue to rise.

  As a general thermal transfer sheet used in the printer, a base sheet {for example, a sheet made of polyethylene terephthalate (hereinafter referred to as “PET sheet”)}, a dye layer formed on one surface of the PET sheet, A thermal transfer sheet comprising a back layer formed on the other surface of the PET sheet can be mentioned. According to the thermal transfer sheet, after the thermal transfer image receiving sheet and the dye layer are stacked so as to face each other, the back layer and a heating device such as a thermal head are brought into contact with each other, and the heating device such as the thermal head is in accordance with image information. An image can be formed on the thermal transfer image-receiving sheet by moving it so as to rub on the back layer while applying energy. At this time, if the back layer has poor slidability (sliding property), the substrate sheet melts and adheres to the thermal head member in the back layer in contact with the thermal head (generally “sticking” or “stick”). ), And there is a large difference in the coefficient of friction between printing and non-printing, and print wrinkles occur. In particular, the heat applied to the thermal head during printing differs based on the image information (in other words, the heat becomes strong or weak depending on the color density), and the temperature of the heat applied to the back layer When a back layer having good slippery only when the temperature is low or a back layer having good slippery only when the temperature of heat applied to the back layer is high, sticking and print wrinkles cannot be prevented. Therefore, the back layer constituting the thermal transfer sheet is required to have a stable slipperiness (slidability) at any temperature from low to high.

  In order to cope with such problems, conventionally, the back layer of the thermal transfer sheet contains an organometallic compound, a phosphorus compound, a sulfur compound, a halogen compound and a mixture thereof as a slipping component, and further a metal soap or the like. A thermal transfer sheet has been proposed (Patent Document 1). According to Japanese Patent Laid-Open No. 2004-260260, it is possible to cope with the speeding up of the printer, stabilize at the time of printing / non-printing at a low friction coefficient for preventing printing wrinkles, and solve the problem of waste generated at the time of long-term printing. Is still inadequate.

JP 2004-90594 A

  In thermal transfer printing, for example, when black is printed and then a thin image is printed, a part of the components in the back layer melts when black is printed, and this dissolved component or liquid component is heated. And it is pushed in by pressure. And how heat is applied varies depending on where the component is present and where it is not. Therefore, the heat generation state changes depending on the location, resulting in a phenomenon of color bleeding (also referred to as “buzz”) (hereinafter referred to as “buzz”). This is a phenomenon that occurs in any of the three colors of yellow (Y), magenta (M), and cyan (C) (colored thermal transfer layer). Such snoring naturally becomes a problem in terms of quality, and there is a problem of eliminating it.

  In addition, the thermal head is in contact with the back layer so as to rub against the back layer of the thermal transfer sheet, and if the sliding property is not good, the residue accumulates at the tip of the thermal head, and when heated, the residue melts and the residue is lost. Causes snoring.

  The present invention has been made in view of such a situation, and in the back layer in contact with the thermal head, the heat applied to the back layer is always stable and good slipperiness (sliding property) at any temperature from low temperature to high temperature. It is an object of the present invention to provide a thermal transfer sheet capable of preventing the occurrence of snoring.

  To achieve the above object, the thermal transfer sheet of the present invention is formed on a base sheet, a dye layer formed on one surface of the base sheet, and a surface of the base sheet opposite to the dye layer. The back layer includes a lubricant, and the lubricant includes a first lubricant having a melting point of 55 to 80 ° C and a second lubricant having a melting point of 25 ° C or less. And a third lubricant having a melting point of 100 ° C. or higher, and the lubricant is 30 to 70% by weight of the first lubricant and 20% by weight or less of the second lubricant with respect to the total weight of the lubricant. And the balance is made of the third lubricant.

  Moreover, the thermal transfer sheet of the present invention for achieving the above object includes a base sheet, a dye layer formed on one surface of the base sheet, and a surface of the base sheet opposite to the dye layer. The back layer includes a lubricant, and the lubricant includes a first lubricant having a melting point of 55 to 80 ° C. and a first lubricant having a melting point of 25 ° C. or less. 2 lubricants and a third lubricant having a melting point of 100 ° C. or higher, and the lubricant is 30 to 80% by weight of the first lubricant and 10% of the second lubricant with respect to the total weight of the lubricant. % Or less, and the balance consists of the third lubricant.

  The second lubricant may be a phosphate ester, and the third lubricant may be a metal soap or a fatty acid derivative.

  Moreover, the said back surface layer contains the said lubricant in binder resin, and the said lubricant may be contained in 1 to 100 weight% with respect to the total weight of the said binder resin.

  According to the present invention, when printing is performed by bringing the thermal head into contact with the back layer of the thermal transfer sheet, the lubricants having different slippery temperatures (that is, different melting points) so that good slipperiness is always obtained. Since a predetermined amount of the first to third lubricants) is contained in the back surface layer, the heat applied to the back surface layer can impart stable lubricity to the thermal transfer sheet at any temperature from low temperature to high temperature. Occurrence of snoring can be prevented.

FIG. 3 is a schematic cross-sectional view showing a state of the thermal head and the thermal transfer sheet during printing by thermal transfer according to the embodiment of the present invention. It is a graph which shows the relationship between lubricity and temperature of the 1st-3rd lubricant which comprises the lubricant of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a state of a thermal head and a thermal transfer sheet during printing by thermal transfer according to an embodiment of the present invention.

  The thermal transfer sheet 1 includes a base sheet 2 {for example, a sheet made of polyethylene terephthalate (hereinafter referred to as “PET sheet”)}, a dye layer 3 formed on one surface of the base sheet 2, and a base sheet 2. And a back layer 4 formed on the other surface of the substrate. In the figure, reference numeral 5 denotes a thermal head, and reference numeral 6 denotes a thermal transfer image receiving sheet.

(Substrate sheet)
As the base material sheet (film) 2 used in the present invention, in addition to the PET sheet, the same material as that used in the conventional thermal transfer sheet can be used as appropriate, and the material is not particularly limited. Examples of preferable material for the base sheet 2 include polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer, and the like. There are plastic films, paper such as condenser paper, paraffin paper, and non-woven fabrics, and the base material sheet 2 may be a composite of these.

  The thickness of the base sheet 2 can be appropriately changed according to the material so that the strength and thermal conductivity are appropriate, but the thickness is suitably in the range of 0.5 to 50 μm, preferably Is in the range of 1.5 to 10 μm.

(Back layer)
A back layer 4 is formed on one side of the base sheet 2 (the top face of the base sheet 2 in the case shown in FIG. 1). The back layer 4 is an essential component in the thermal transfer sheet 1 of the present invention, and includes a binder resin and a lubricant component added to the binder resin, that is, a lubricant (a first lubricant, a second lubricant, and a third lubricant described later). .

  There is no limitation in particular about binder resin of the back surface layer 4 used by this invention, A conventionally well-known resin etc. can be used. In particular, a polymer having a relatively high glass transition temperature (Tg) is preferably used in order to protect against instantaneous thermal energy from the thermal head. For example, cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polymethacrylic acid Examples thereof include vinyl resins such as ethyl ester, polyacrylamide, and acrylonitrile-styrene copolymer, polyimide resins, polyamideimide resins, polyester resins, polyurethane resins, silicon-modified or fluorinated urethanes, and acrylic resins. Among these, cellulose-based, acetal-based, butyral-based, acrylic resin-based, acrylonitrile-styrene copolymer system, polyester-based, polyurethane resin-based and the like are preferable.

(Curing agent)
Moreover, it is good also as making the said binder resin contain the hardening | curing agent for hardening binder resin. By containing a curing agent in the binder resin, the heat resistance of the back layer 4 can be improved, and the slipperiness of the back layer 4 under high energy can be improved. Furthermore, the strength of the back surface layer 4 can be improved and snoring can be prevented. As such a curing agent, for example, when using a binder resin having a reactive group such as a hydroxyl group among the above binder resins (for example, an acetal-based active hydrogen-containing resin), a polyisocyanate is used as the curing agent. And water-soluble or water-dispersed emulsion systems such as chelate compounds can be suitably used.

  The back layer 4 can further contain a resin filler (tack). The resin filler component is used in a range where an effect can be expected in order to further improve the lubricity. Preferable specific examples of the resin filler include vinyl chloride-ethyl acrylate copolymer.

(Lubricant)
The back layer 4 contains a first lubricant having a melting point of 55 to 80 ° C., a second lubricant having a melting point of 25 ° C. or less, and a third lubricant having a melting point of 100 ° C. or more. Hereinafter, each lubricant contained in the back layer 4 will be specifically described.

(First lubricant)
The back layer 4 contains a first lubricant having a melting point of 55 ° C to 80 ° C. Although the details will be described later, the first lubricant is contained in order to compensate for the lubricity of the predetermined gradation region which is lowered when the content of the second lubricant with respect to the total weight of the lubricant is 20% by weight or less.

  The first lubricant is solid at a temperature lower than the melting point, exhibits no lubricity in the solid state, and exhibits lubricity from around the melting point. Therefore, in consideration of the lubricity of the back layer 4 in the low gradation region, the melting point of the first lubricant contained in the back layer 4 is preferably as low as possible. However, when the melting point of the first lubricant is less than 55 ° C., depending on the storage environment, the component of the first lubricant may be liquefied during storage of the thermal transfer sheet, and the dye surface may be contaminated or blocked during storage. . For example, when the first lubricant having a melting point of 40 ° C. is contained in the back layer 4, the first lubricant dissolves in quality by being placed in an environment of 40 ° C. (in other words, during storage). Influence will come out. On the other hand, when the melting point of the first lubricant is higher than 80 ° C., the first lubricant cannot exhibit lubricity until it reaches a temperature higher than 80 ° C., and cannot provide lubricity in the middle gradation region. . Therefore, the back surface layer 4 in the present invention contains a first lubricant whose melting point is in the range of “55 ° C. to 80 ° C.”.

  The first lubricant is not particularly limited as long as it is made of a material capable of setting the melting point of the first lubricant to “55 ° C. to 80 ° C.”. Preferred specific examples of the first lubricant include, for example, organometallic compounds, phosphorus And at least one selected from the group consisting of a series compound, a sulfur series compound, a halogen series compound, a fatty acid, a fatty acid derivative (for example, fatty acid ester, fatty acid amide, etc.) and a mixture thereof. According to these materials, since the melting point of the first lubricant can be easily set in the range of “55 ° C. to 80 ° C.”, it can be suitably used as the material of the first lubricant. In addition, examples of the first lubricant include lead soap, sulfur-based compounds, and phosphorus compounds. Among these, there are substances that cause a problem of transfer to the transfer layer at the time of winding because of their relatively low melting points. . Therefore, in order to have a melting point at a temperature higher than the storage state of the thermal transfer sheet (specifically 55 to 80 ° C.) and to always exhibit lubricity in a wide energy range, several materials having different melting points are mixed. Are preferably used.

(Second lubricant)
The back layer 4 contains a second lubricant having a melting point of “25 ° C. or lower”. The second lubricant is characterized in that the melting point is “25 ° C. or lower”, which is lower than the melting point of the first lubricant, 55 to 80 ° C.

  The second lubricant having a melting point of 25 ° C. or lower is a liquid even at normal temperature (normal temperature in the present specification means 25 ° C.), and therefore can exhibit good lubricity in all gradation regions. Even if the first lubricant and the third lubricant are not included in the back layer 4 (even when the second lubricant is used alone), the back layer 4 is provided with a lubricity for all gradation regions. It becomes possible to do. However, since the second lubricant is a liquid lubricant, if the content of the second lubricant contained in the back layer 4 is large, it tends to cause snoring.

  Specifically, when the content of the second lubricant is more than 20% by weight with respect to the total weight of the lubricant, the second lubricant, which is liquid at normal temperature, easily oozes out, and thus snore is likely to occur. Therefore, in the second lubricant contained in the back layer 4 in the present invention, the content of the second lubricant is specified in a range of 20% by weight or less with respect to the total weight of the lubricant. More specifically, when the first lubricant is contained in an amount of 30 to 70% by weight with respect to the total weight of the lubricant (total weight of the first lubricant, the second lubricant, and the third lubricant), the content of the second lubricant is 20 weights. When the first lubricant is contained in an amount of 30 to 80% by weight, the second lubricant is contained in an amount of 10% by weight or less. Occurrence of snoring can be prevented by containing the second lubricant in the range of 20% by weight or less.

  Note that the content of the second lubricant is not particularly limited as long as the content of the second lubricant is 20% by weight or less with respect to the total weight of the lubricant, but the content is low when the content of the second lubricant is less than 1% by weight. The smoothness in the gradation area and the middle gradation area (especially in the low gradation area) cannot be exhibited effectively. Considering such points, the content of the second lubricant is preferably 1% by weight or more and 20% by weight or less, more preferably 5% by weight or more and 20% by weight or less, based on the total weight of the lubricant. .

  On the other hand, when the content of the second lubricant is 20% by weight or less with respect to the total weight of the lubricant, although the generation of snoring can be prevented, the content of the second lubricant is reduced. Therefore, there is a concern about a decrease in slipperiness in the middle gradation area and the high gradation area. However, since the back layer 4 in the present invention contains at least 30% by weight or more of the first lubricant having a melting point of 55 to 80 ° C. with respect to the total weight of the lubricant, the content of the second lubricant is 20% by weight. Even in the case described below, the slipperiness in the gradation region can be ensured without reducing the slipperiness in the intermediate gradation region. Further, as will be described later, the back layer 4 in the present invention contains at least 10% by weight or more of a third lubricant having a melting point of 100 ° C. or higher with respect to the total weight of the lubricant. The smoothness of the gradation region can be ensured without lowering. That is, according to the present invention, the first lubricant and the third lubricant compensate for the decrease in slipperiness caused by the content of the second lubricant being 20% by weight or less in order to prevent the occurrence of snoring. Thus, it is possible to exhibit excellent slipperiness for all gradation regions.

  In view of preventing the occurrence of snoring, the content of the second lubricant is particularly preferably 10% by weight or less with respect to the total weight of the lubricant. In addition, when the content of the second lubricant is 10% by weight or less, the slipperiness of the low gradation region can be ensured, but there is a concern that the slipping of the middle gradation region and the high gradation region may be deteriorated. The Rukoto. However, as described above, even when the content of the second lubricant is 10% by weight or less, in the present invention, the first lubricant is contained at least 30% by weight or more based on the total weight of the lubricant. Is contained at least 10% by weight or more, it is possible to effectively prevent the occurrence of snoring and not to reduce the slipperiness of the middle gradation region and the high gradation region.

  If the content of the first lubricant is 30% by weight or more with respect to the total weight of the lubricant, the slipperiness in the middle gradation region can be sufficiently expressed. The content of the third lubricant with respect to the total weight of is required to be at least 10% by weight. Therefore, in the present invention, when the content of the second lubricant is 20% by weight or less, the upper limit of the content of the first lubricant is defined as 70% by weight or less, and the content of the second lubricant is 10% by weight. %, The upper limit of the content of the first lubricant is defined as 80% by weight or less.

  The second lubricant is not particularly limited as long as it is made of a material capable of setting the melting point of the second lubricant to 25 ° C. or lower (that is, normal temperature or lower), and a preferable specific example of the second lubricant is, for example, phosphate ester. Examples of phosphoric acid esters include (1) phosphoric acid monoesters or diesters of saturated or unsaturated higher alcohols having 6 to 20 carbon atoms, and (2) phosphoric acid monoesters of polyoxyalkylene alkyl ethers or polyoxyalkylene alkyl allyl ethers. Ester or diester, (3) Phosphoric acid monoester or diester of the above-mentioned saturated or unsaturated higher alcohol alkylene oxide adduct (average addition mole number of 1 to 8), (4) Alkylphenol having an alkyl group of 8 to 12 carbon atoms Alternatively, phosphoric acid monoester or diester of alkyl naphthol can be used.

  Examples of the saturated or unsaturated higher alcohol in the above (1) and (3) include cetyl alcohol, stearyl alcohol, oleyl alcohol and the like. Examples of the alkylphenol in the above (4) include nonylphenol, dodecylphenol, diphenylphenol and the like.

(3rd lubricant)
In addition, the back layer 4 has a second lubricant content of 20% by weight or less with respect to the total weight of the lubricant, so that the slipperiness in a gradation region (especially a high gradation region) in which the reduction is a concern. In order to give, the 3rd lubricant with melting | fusing point "100 degreeC or more" is contained. The third lubricant is a high-melting-point solid lubricant and, like the first lubricant, is a solid at room temperature and therefore does not exhibit lubricity, but exhibits lubricity from the vicinity of the melting point. The melting point of the third lubricant is not particularly limited as long as it is “100 ° C. or higher”, and, for example, 125 ° C., 230 ° C. in order to ensure slipping in a higher temperature region (high gradation region) than the first lubricant and the second lubricant. About the appropriate one can be selected and used. The upper limit of the melting point of the third lubricant is not particularly limited as long as it is “100 ° C. or higher”, but it is 250 ° C. or lower in consideration of the point that the maximum heat is about 300 ° C. instantaneously applied from the thermal head. Is preferred.

  The content of the third lubricant is the amount of the remainder containing the predetermined amount of the first lubricant and the second lubricant, and the total of the first lubricant, the second lubricant, and the third lubricant is 100 wt. %. In addition, when the content of the third lubricant contained in the total weight of the lubricant is less than 10% by weight, it is difficult to express the lubricity in the high gradation region. Since the upper limit of the total content of the first lubricant and the second lubricant contained in the weight is 90% by weight, the third lubricant is contained in at least 10% by weight or more based on the total weight of the lubricant. It does not reduce the slipperiness in the tone area. That is, according to the present invention in which the third lubricant is contained in an amount of 10% by weight or more with respect to the total weight of the lubricant, it is possible to exhibit good lubricity in a high gradation region.

  The third lubricant is not particularly limited as long as it is made of a material capable of setting the melting point of the third lubricant to “100 ° C. or higher”, but a metal soap that can easily adjust the melting point of the third lubricant to “100 ° C. or higher”. It is preferable to use fatty acid amide which is a fatty acid derivative. Preferable specific examples of the metal soap include polyvalent metal salts of alkyl phosphate esters, polyvalent metal salts of fatty acids, metal salts of alkyl carboxylic acids, and the like. As the polyvalent metal salt of an alkyl phosphate, those known as additives for plastics can be used. The polyvalent metal salt of an alkyl phosphate ester is generally obtained by substituting an alkali metal salt of an alkyl phosphate ester with a polyvalent metal, and various grades are available. Specific examples of the fatty acid amide include ethylene bisoleic acid amide and methylene bis stearic acid amide.

  Although these metal soaps and fatty acid amides generally exhibit good lubricity when the heat applied to the back layer is high temperature / high energy (high gradation region), the heat applied to the back layer is low / low energy (low) In the gradation area), the slipperiness greatly decreases. Therefore, when only the third lubricant is contained, printing wrinkles are generated due to the difference in lubricity between printing and non-printing. Therefore, in the present invention, the third lubricant that exhibits good lubricity when the heat applied to the back layer is high temperature / high energy (high gradation region) and the first lubricant that exhibits excellent lubricity in all gradation regions. In combination with 2 lubricants and the 1st lubricant that expresses particularly excellent lubricity in the middle gradation range and adjusting the blending ratio, the heat applied to the back layer is low / low while preventing the occurrence of snoring. It is possible to obtain a stable friction coefficient (sliding property) in a wide range from the energy state (low gradation region) to the heat applied to the back layer from a high temperature / high energy state (high gradation region).

  By including the above-mentioned predetermined amounts of the lubricants composed of the first lubricant, the second lubricant, and the third lubricant, the back layer can be lubricated until the heat applied to the back layer reaches from low to high. Thus, good slipperiness can be exhibited and the occurrence of snoring can be prevented. Specifically, according to the present invention, the occurrence of snoring can be prevented by setting the content of the second lubricant to 20% by weight or less based on the total weight of the lubricant. Furthermore, according to the present invention, the first lubricant for ensuring the lubricity in the middle gradation region which is insufficient when the content of the second lubricant is 20% by weight or less is contained, and the high gradation region is contained. Since the third lubricant for ensuring the slipperiness in 10% by weight or more is contained, it is possible to develop good slipperiness in any region from the low gradation region to the high gradation region.

  The material (component) of the lubricant is not particularly limited as long as it is made of a material (component) having a predetermined melting point as described above. However, when the thermal transfer sheet is used as an ink ribbon, since the ink ribbon is wound (winded up by a roll), the dye layer 3 and the back layer 4 are in contact with each other, and a lubricant (particularly the second lubricant) is used. When silicon is contained in the material of (), the silicon contained in the lubricant floats in the wound state (moves over) and moves to the dye layer side to affect (the dye layer is Become contaminated). Therefore, the first lubricant, the second lubricant, and the third lubricant (particularly the second lubricant that is in a liquid state at room temperature) are composed of components that do not contain silicon (the lubricant does not contain silicon). Is preferred. If the lubricant is composed of a component that does not contain silicon, the dye layer is not contaminated and it is possible to prevent snoring.

  Moreover, although the content of the lubricant contained in the binder resin varies depending on the binder resin used, the presence or absence of the curing agent, and the content of the curing agent, the content of the lubricant (of the first lubricant, the second lubricant, and the third lubricant) When the total content) is less than 1% by weight with respect to the total weight of the binder resin, it becomes difficult to impart desired lubricity to the back layer 4, and when it is 100% by weight or more, The binder resin may not be able to bind the lubricant. Considering such points, the content of the lubricant with respect to the total weight of the binder resin is preferably 1% by weight or more and 100% by weight or less, and more preferably 20% by weight or more and 80% by weight or less.

The method for forming the back layer 4 is not limited. For example, the coating solution is prepared by dissolving or dispersing the above-mentioned predetermined components in a suitable solvent such as acetone, methyl ethyl ketone, toluene, xylene, ethanol, and the like. It can be formed by coating the working liquid on a base material sheet by a conventional coating means such as a gravure coater, roll coater, wire bar or the like and drying it. Although there is no particular limitation on the amount of coating (that is, the thickness of the back layer), considering the point to impart the desired slip the rear layer 4, the coating weight is 0.1 g / m ² to 2 on a solids basis preferably .0g / m ² or less, and more preferably ^{0.2g / m 2 ~1.5g / m 2} . By forming the back layer 4 so as to be in such a range, the back layer 4 having sufficient performance (slidability) can be formed.

(Dye layer)
A dye layer 3 is formed on the other surface of the substrate sheet 2 (the lower surface of the substrate sheet 2 in the case shown in FIG. 1). As the dye layer 3 (thermal transfer color material layer), a layer containing a sublimation dye is formed in the case of a sublimation type thermal transfer sheet, and a wax ink layer colored with a pigment is formed in the case of a heat melting type thermal transfer sheet. To do. As the material of the dye layer 3, conventionally known materials can be appropriately used according to the purpose, and are not particularly limited.

  Examples of the dye include azomethines such as diarylmethane, triarylmethane, thiazole, merocyanine, pyrazolone methine and the like, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazolazomethine, imidazoazomethine, and pyridone azomethine. , Xanthene, oxazine, dicyanostyrene, cyanomethylene represented by tricyanostyrene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrroleazo, pyralazo, imidazoleazo, Azos such as thiadiazole azo, triazole azo, dizazo, spiropyran, indolinospiropyran, fluoran, rhodamine lactam, naphthoquinone, anne Rakinon system include the quinophthalone like.

  As the binder of the dye layer 3, any conventionally known binder resin can be used. Examples of preferable binder resins include ethyl cellulose resin, hydroxyethyl cellulose resin, ethyl hydroxy cellulose resin, hydroxypropyl cellulose resin, methyl cellulose resin, cellulose acetate resin, Cellulose resins such as cellulose butyrate resin, polyvinyl alcohol resins, polyvinyl acetate resins, polyvinyl acetal resins such as polyvinyl acetoacetal resins and polyvinyl butyral resins, vinyl resins such as polyvinyl pyrrolidone resins and polyacrylamide resins, polyester resins, phenoxy Examples thereof include resins. Among these, cellulose resins, acetal resins, polyester resins, phenoxy resins, and the like are particularly preferable from the viewpoints of heat resistance, dye transferability, and the like.

  The method for forming the dye layer 3 is not particularly limited. For example, the above-described dye and binder resin, and further additives such as a release agent and inorganic fine particles may be added as necessary, and toluene, ethyl ethyl ketone, isopropyl Reverse roll coating using gravure printing, die coating printing, bar coating printing, screen printing, or gravure printing with a coating solution dissolved in an appropriate organic solvent such as alcohol, ethanol, cyclohexanone, or DMF, or dispersed in an organic solvent or water. It can be formed by applying and drying by means such as printing.

  Next, the operation of the first to third lubricants will be described. FIG. 2 is a graph showing the relationship between the slipperiness (slip) of the first to third lubricants constituting the lubricant of the present invention and the temperature of heat applied to the back layer. As the vertical axis of the graph goes upward (in the direction of the arrow), the slip becomes better, and as the horizontal axis goes to the right (in the direction of the arrow), the temperature of heat applied to the back layer becomes higher. (1) shown in FIG. 2 is a first lubricant (lubricant having a melting point within the range of the present invention), (2) is a second lubricant (lubricant having a melting point within the range of the present invention), ( 3) is a third lubricant (a lubricant having a melting point at a temperature within the range of the present invention).

  In FIG. 2, the first lubricant (1) is solid at room temperature and is not slippery. However, as the temperature of heat applied to the back layer approaches the melting point, the slipperiness becomes better, and as the temperature rises from a certain temperature. Lubricity deteriorates. The second lubricant (2) is liquid even at room temperature and has good slipping from room temperature. The third lubricant (3) is solid at room temperature and is not slippery, but as the temperature of the heat applied to the back layer rises and approaches the melting point, the slipperiness gradually improves and the slip of the first lubricant (1) deteriorates. Lubricity becomes good at the starting temperature. As described above, in the present invention, since the lubricant has good slipperiness at least one of the first to third lubricants at all temperatures, the back layer always shows good slipperiness stably. Can do.

  Next, an Example is given and this invention is demonstrated further more concretely. Hereinafter, unless otherwise specified, parts or% is based on weight.

Example 1
A polyethylene terephthalate film having a thickness of 6 μm is used as a base film, and a coating solution for the back layer having the following composition is applied on the base film so as to be about 1.0 g / m ² when dried, and then dried to form a back layer. Formed. Further, a dye layer (thermal transfer color material layer) coating solution having the following composition was applied to the other surface of the base film so as to be about 1.0 g / m ² when dried, and then dried to obtain a dye layer. Formed. Thereby, the thermal transfer sheet of Example 1 was obtained.

<Back layer coating liquid>
・ 4.55 parts of polyvinyl butyral resin (SREC BX-1 Sekisui Chemical Co., Ltd.)
・ 21 parts of polyisocyanate (Pernock D750-45, solid content 45% by mass, Dainippon Ink & Chemicals, Inc.)
・ Talc (Microace P-3 Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Total 1st to 3rd lubricant 3 parts ・ First lubricant: Phosphate ester (melting point 70 ° C.) (70%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (10%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)
-Methyl ethyl ketone 100 parts-Toluene 100 parts In addition, the numerical value in () of the said 1st-3rd lubricant represents each compounding ratio with respect to the total amount of lubricants. (The same applies to the following examples and comparative examples)

<Coating liquid for dye layer>
・ MS-RED-G 2 parts (Disper Red 60 Mitsui Toatsu Chemicals)
・ Macrolex Red Violet R 1.5 parts (Disperse Violet 26 Bayer)
・ 3.5 parts of polyvinyl acetal resin (Eslex KS-5 Sekisui Chemical Co., Ltd.)
Toluene 46.5 parts Methyl ethyl ketone 46.5 parts

(Example 2)
A thermal transfer sheet of Example 2 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (30%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (10%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (60%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Example 3)
A thermal transfer sheet of Example 3 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (30%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (10%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearate (melting point 125 ° C) (60%)
(SZ-PF Sakai Chemical Industry Co., Ltd.)

Example 4
A thermal transfer sheet of Example 4 was prepared in the same manner as in Example 1 except that fatty acid ester (Unistar H-476 NOF Co., Ltd.) was used as the first lubricant and the blending ratio was changed.
・ Total 3 parts of first to third lubricants ・ First lubricant: fatty acid ester (melting point 62 ° C.) (50%)
(Unistar H-476 NOF Corporation)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (30%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Example 5)
A thermal transfer sheet of Example 5 was prepared in the same manner as in Example 1 except that oleic acid amide (fatty acid amide ON-N Kao Co., Ltd.) was used as the first lubricant and the blending ratio was changed.
・ Total 3 parts of first to third lubricants ・ First lubricant: oleic acid amide (melting point 72 ° C.) (50%)
(Fatty Acid Amide ON Kao Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (30%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Example 6)
A thermal transfer sheet of Example 6 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (50%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (5%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (45%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Example 7)
A thermal transfer sheet of Example 7 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (50%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (1%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (49%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Example 8)
A thermal transfer sheet of Example 8 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (70%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: ethylene bisoleic acid amide (melting point 119 ° C.) (10%)
(Sripacks O Nippon Kasei Co., Ltd.)

Example 9
A thermal transfer sheet of Example 8 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (70%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: methylene bis stearic acid amide (melting point 142 ° C.) (10%)
(Bisamide LA Nippon Kasei Co., Ltd.)

(Example 10)
A thermal transfer sheet of Example 10 was produced in the same manner as in Example 1 except that the “back layer coating solution” was changed as follows to form a back layer.
<Back layer coating liquid>
・ 4.55 parts of cellulose acetate acetate propionate resin (CAP482-0.5 Eastman Chemical Company)
・ 21 parts of polyisocyanate (Pernock D750-45, solid content 45% by mass, Dainippon Ink & Chemicals, Inc.)
・ Talc (Microace P-3 Nippon Talc Kogyo Co., Ltd.) 0.7 part ・ Total 1st to 3rd lubricant 3 parts ・ First lubricant: Phosphate ester (melting point 70 ° C.) (70%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (10%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)
・ Methyl ethyl ketone 100 parts ・ Toluene 100 parts

(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (50%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (50%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
・ Third lubricant: None

(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (50%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: None-Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (50%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 3)
A thermal transfer sheet of Comparative Example 3 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: none ・ Second lubricant: phosphate ester (melting point 15 ° C.) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
-Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (80%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 4)
A thermal transfer sheet of Comparative Example 4 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: zinc stearate (melting point 125 ° C.) (50%)
(SZ-PF Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (30%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 5)
A thermal transfer sheet of Comparative Example 5 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (50%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Zinc stearate (melting point 125 ° C) (20%)
(SZ-PF Sakai Chemical Industry Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (30%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 6)
A thermal transfer sheet of Comparative Example 6 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: fatty acid ester (melting point 53 ° C.) (50%)
(Unistar H-476D NOF Corporation)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (30%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 7)
A thermal transfer sheet of Comparative Example 7 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (20%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (60%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 8)
A thermal transfer sheet of Comparative Example 7 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (30%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (30%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (40%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Comparative Example 9)
A thermal transfer sheet of Comparative Example 9 was prepared in the same manner as in Example 1 except that the back layer was formed by changing the lubricant contained in the “back layer coating solution” as follows.
・ Total 3 parts of first to third lubricants ・ First lubricant: Phosphate ester (melting point 70 ° C.) (75%)
(Phoslex A-18 Sakai Chemical Industry Co., Ltd.)
-Second lubricant: Phosphate ester (melting point 15 ° C) (20%)
(Pricesurf A208N Daiichi Kogyo Seiyaku Co., Ltd.)
-Third lubricant: Zinc stearyl phosphate (melting point 230 ° C) (5%)
(LBT1830 purification Sakai Chemical Industry Co., Ltd.)

(Evaluation test)
The thermal transfer sheets of Examples 1 to 10 and Comparative Examples 1 to 9 were printed on a thermal transfer image receiving sheet (image receiving paper) prepared as described below by a thermal head printer under the same printing conditions as described below. After the image was formed and printed on the image receiving paper, the printing state (described as “solid black printing” and “real printing gray” in Table 1), printing stain, and blocking resistance were evaluated. The results are shown in Table 1.

  Table 1 also shows melting points and blending ratios (%) of the first to third lubricants contained in the back layers of the thermal transfer sheets of Examples 1 to 10 and Comparative Examples 1 to 9. The blending ratio (%) is a ratio in the lubricant (not the total ratio).

  The production method and printing conditions of the thermal transfer image receiving sheet (image receiving paper) were as follows.

(How to make a thermal transfer image receiving sheet (image receiving paper))
Using RC paper (STF-150, manufactured by Mitsubishi Paper Industries Co., Ltd.) as the base sheet, the porous layer forming coating solution and the receiving layer forming coating solution having the following compositions were heated to 50 ° C., respectively, and slide coating was performed. , Applied to a thickness of 30 μm and 5 μm when dried, cooled and gelled at 5 ° C. for 1 minute, and dried at 50 ° C. for 5 minutes to obtain a thermal transfer image-receiving sheet (image-receiving paper) It was.

<Porous layer forming coating solution>
・ Hollow particles (HP-91 Rohm and Haas) (as solid content) 70 parts ・ Gelatin (RR Nitta Gelatin Co., Ltd.) (as solid content) 30 parts ・ Interface slip material (Surfinol 440 Nissin Chemical Industry) 0.15 parts

<Coating liquid for forming receiving layer>
・ Emulsion (as solids) 70 parts ・ Resin filler (VB900) (as solids) 15 parts ・ Gelatin (RR Nitta Gelatin Co., Ltd.) (as solids) 15 parts ・ Silicone mold release agent (Surfinol 440) Shin-Etsu Chemical Co., Ltd.) 10 parts ・ Interface slip material (Surfinol 440 Nissin Chemical Industry Co., Ltd.) 1 part

  For the synthesis of the emulsion of the coating solution for forming the receiving layer, in a 500 mL Erlenmeyer flask, 103 g of styrene, 54 g of ethyl acrylate, 41 g of lauryl acrylate, 2 g of acrylic acid, emulsifier (AQUALON HS-10 Daiichi Kogyo Seiyaku Co., Ltd.) 1 .9 g was added and stirred and mixed (hereinafter referred to as monomer A). In a 1 L three-necked flask, 200 g of distilled water was added and heated to 80 ° C., and about 20% of the total amount of monomer A was added and stirred for 10 minutes. Thereafter, 0.2 g of ammonium persulfate dissolved in 20 g of pure water was added and stirred for 10 minutes, and then the remaining 80% of the monomer A was dropped with a dropping funnel over 3 hours and further stirred for 3 hours. Thereafter, the mixture was cooled to room temperature and filtered through # 150 mesh (Japanese woven fabric) to obtain an emulsion. Molecular weight 242273, Tg 50 ° C. Further, from the molecular weight of styrene, ethyl acrylate and lauryl acrylate and the amount used for the reaction, the respective molar ratios are 58%, 32% and 10%.

  As the resin filler, a vinyl chloride-ethyl acrylate copolymer (monomer blending ratio is 90% vinyl chloride, 10% ethyl acrylate) and Tg 70 ° C. (VB900 Nissin Chemical Industry Co., Ltd.) was used.

(Printing conditions)
Thermal head printer; KGT-217-12MPL20 (Kyocera Corporation)
Heating element average resistance value: 2994 (Ω)
Main scanning direction printing density; 300 dpi
Sub-scanning direction print density; 300 dpi
Applied power: 0.10 (w / dot)
1 line cycle: 5 (msec.)
Printing start temperature; 40 (° C)
Applied pulse (gradation control method): Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 in one line period and having a pulse length obtained by equally dividing one line period into 256 The duty ratio of the divided pulses was fixed to 70%, and the number of pulses per line period was divided into 15 from 0 to 255. Thereby, different energy can be given to 15 steps.
Print pattern: Solid black

  Evaluation criteria of the evaluation test were as follows.

(Real machine print black solid)
By using a digital photo printer Megapixel II manufactured by Altec Co., Ltd., and a combination of the thermal transfer sheet produced in the examples and comparative examples and a genuine Megapixel II photographic paper (postcard size), (255: Density Max), and the obtained printed material was checked for the presence of printing defects such as wrinkles, transfer unevenness, and transfer omission. Evaluation was performed according to the following criteria. The meanings of symbols in Table 1 are as follows.
◯: No print defects such as wrinkles, transfer unevenness, and transfer omission occur in the printed material.
X: Print defects such as wrinkles, transfer unevenness, and transfer omission occur in the printed matter.

(Actual machine print gray)
By using a digital photo printer Megapixel II manufactured by Altec Co., Ltd., a combination of the thermal transfer sheet produced in the examples and comparative examples, and a genuine megapixel II photographic paper (postcard size), a solid black (tone value 128 / The printing pattern of No. 255) was printed, and the obtained printed matter was checked for the presence of printing defects such as wrinkles, transfer unevenness, and transfer omission. Evaluation was performed according to the following criteria. The meanings of symbols in Table 1 are as follows.
◯: No print defects such as wrinkles, transfer unevenness, and transfer omission occur in the printed material.
X: Print defects such as wrinkles, transfer unevenness, and transfer omission occur in the printed matter.

(Print stains)
A solid pattern and a halftone continuous pattern were printed with a sublimation printer (Mitsubishi Electric Corporation, trade name CP8000), and the presence or absence of print stains due to snoring (tailing) was visually observed. The meanings of symbols in Table 1 are as follows.
◎: No printing stain due to snoring ○: Slight printing smudge due to snoring is observed, but there is no problem in practical use ×: There is a printing smudge due to snoring, and there is a defect in printing

(Blocking resistance)
The dye transfer layer and the back layer of each thermal transfer sheet were overlapped with each other on the thermal transfer sheets of Examples and Comparative Examples prepared above, and a load of 20 kg / cm ² was applied and stored at 60 ° C. for 100 hours. The blocking between the dye layer and the back layer of the thermal transfer sheet after storage was visually evaluated according to the following criteria. The meanings of symbols in Table 1 are as follows.
○: No blocking between the dye layer and the back layer. It is good.
X: There is blocking between the dye layer and the back layer, which is poor.

  As apparent from Table 1 above, in the thermal transfer sheets of Examples 1 to 10 of the present invention, the melting points and blending ratios of the first to third lubricants are within the scope of the present invention, and “real machine printing black solid”, “real machine” All the evaluations of “print gray”, “print stain” and “blocking resistance” were good. In particular, the thermal transfer sheets of Examples 2, 3, 6, and 7 in which the content of the second lubricant was 10% by weight or less had no print stain due to chatter, and evaluation for “print stain” was particularly good.

  On the other hand, when Comparative Example 2 without the second lubricant and Comparative Example 3 without the first lubricant were confirmed, Comparative Example 2 without the second lubricant and Comparative Example 3 without the first lubricant were “actual machine prints”. The “gray” rating was bad.

  In addition, when Comparative Examples 4 to 6 in which the melting point is not considered are confirmed, three types of the first to third lubricants are used, but Comparative Example 4 in which the melting point of the first lubricant is outside the scope of the present invention is “ The evaluation of “real machine printing gray” was bad. In Comparative Example 5, where the melting point of the second lubricant was outside the range of the present invention, the evaluation of “actual machine printing gray” was bad. In Comparative Example 6, where the melting point of the first lubricant was outside the range of the present invention, the evaluation of “blocking resistance” was poor.

  Further, when Comparative Examples 1 and 7 to 9 in which the contents of the first to third lubricants are not considered are confirmed, Comparative Example 7 in which the content of the first lubricant is out of the scope of the present invention is small. The evaluation of “Gray” was bad. In Comparative Example 1 and Comparative Example 8 in which the content of the second lubricant was outside the range of the present invention, the evaluation of “print stain” was bad. Further, in Comparative Example 9 in which the content of the second lubricant was within the range of the present invention but the content of the third lubricant was outside the range of the present invention, the evaluation of “actual machine black solid” was poor.

  As described above, it can be seen that Comparative Examples 1 to 9 cannot obtain satisfactory evaluations of “real printing black solid”, “real printing gray”, “printing stain”, and “blocking resistance”.

DESCRIPTION OF SYMBOLS 1 Thermal transfer sheet 2 Base material sheet 3 Dye layer 4 Back layer 5 Thermal head 6 Thermal transfer image receiving sheet

Claims (5)

  A thermal transfer sheet comprising: a base sheet; a dye layer formed on one side of the base sheet; and a back layer formed on a side opposite to the dye layer of the base sheet, The back layer contains a lubricant, and the lubricant comprises a first lubricant having a melting point of 55 to 80 ° C., a second lubricant having a melting point of 25 ° C. or less, and a third lubricant having a melting point of 100 ° C. or more. In addition, the lubricant contains 30 to 70% by weight of the first lubricant and 20% by weight or less of the second lubricant with respect to the total weight of the lubricant, and the balance is the third lubricant. Thermal transfer sheet.   A thermal transfer sheet comprising: a base sheet; a dye layer formed on one side of the base sheet; and a back layer formed on a side opposite to the dye layer of the base sheet, The back layer contains a lubricant, and the lubricant comprises a first lubricant having a melting point of 55 to 80 ° C., a second lubricant having a melting point of 25 ° C. or less, and a third lubricant having a melting point of 100 ° C. or more. In addition, the lubricant contains 30 to 80% by weight of the first lubricant and 10% by weight or less of the second lubricant with respect to the total weight of the lubricant, and the balance is the third lubricant. Thermal transfer sheet.   The thermal transfer sheet according to claim 1, wherein the second lubricant is a phosphate ester.   The thermal transfer sheet according to any one of claims 1 to 3, wherein the third lubricant is a metal soap or a fatty acid derivative. The back layer comprises the binder in a binder resin,
The thermal transfer sheet according to any one of claims 1 to 4, wherein the lubricant is contained in a range of 1 wt% to 100 wt% with respect to the total weight of the binder resin.

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