JP6079382B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet.

  As a method for forming an image using thermal transfer, a thermal transfer sheet in which a dye layer containing a sublimation dye is provided on a base material and a thermal transfer image receiving sheet in which a receiving layer is provided on another base material are superposed on each other. A sublimation thermal transfer method for forming a full-color image is known. Since this method uses sublimation dyes as color materials, it is excellent in halftone reproducibility and gradation, and a full color image as it is on the original can be clearly displayed on the image receiving sheet. It is applied to color image formation for computers. The image is of a high quality comparable to a silver salt photograph.

  In the image formation using the sublimation type thermal transfer method, when the releasability between the dye layer of the thermal transfer sheet and the receiving layer of the thermal transfer image receiving sheet is low, the dye layer of the thermal transfer sheet is formed on the thermal transfer image receiving sheet during image formation. When the dye layer is fused to the receiving layer and the dye layer is peeled off from the receiving layer after the image is formed, it may cause generation of peeling sound, running failure, generation of peeling lines, and the like. There may also be a problem of abnormal transfer in which the dye layer is fused to the receiving layer and the dye layer is transferred as a layer. Therefore, good releasability is required between the dye layer of the thermal transfer sheet and the receiving layer of the thermal transfer image receiving sheet. In particular, with the recent increase in the speed of printers, the printing energy during image formation continues to increase, and the dye layer of the thermal transfer sheet and the receiving layer of the thermal transfer image receiving sheet are likely to be fused. Therefore, extremely good releasability is required between the dye layer of the thermal transfer sheet and the receiving layer of the thermal transfer image receiving sheet so as not to cause fusion even when the printing energy is increased.

  In order to improve the releasability between the dye layer and the receiving layer, it is considered preferable to contain various release agents in the dye layer. For example, Patent Document 1 discloses a dye containing silicone oil. Layers have been proposed. Besides these, phosphate esters and various fatty acid esters are known as mold release agents. Various fatty acid esters are roughly classified into liquid fatty acid esters and solid fatty acid esters.

  Among various release agents, silicone oil and liquid release agents such as phosphate esters are known to have better release properties than solid release agents, and high release properties are required. In some areas, its use tends to be preferred. Further, it is known that in order to improve the releasability, it is preferable to increase the content of the release agent in the dye layer.

  The thermal transfer sheet is generally stored and used in a wound state. When the thermal transfer sheet is wound up, the dye layer and the back layer are in direct contact with each other, and if the storage stability of the sublimable dye in the dye layer is low, A so-called kick occurs in which the dye moves to the back layer. The occurrence of kick is considered to be closely related to the content of the release agent in the dye layer, and as the content of the release agent in the dye layer increases, the degree of occurrence of kick increases. Become. In particular, a dye layer containing a liquid release agent having excellent releasability has a higher degree of kick generation than a dye layer containing a solid release agent. On the other hand, when the content of the release agent is the same, the dye layer containing the solid release agent has a lower degree of kick than the dye layer containing the liquid release agent. However, in order to improve the releasability of the dye layer using a solid release agent, it is necessary to increase the content in the dye layer rather than the liquid release agent. It is difficult to prevent the occurrence of kicks while using it to improve releasability. In other words, the improvement in releasability and the effect of preventing kicks are in a trade-off relationship. If the focus is on improving releasability, the degree of kicking will increase, while the prevention of kicking will occur. When the main focus is on, the releasability between the dye layer and the receiving layer cannot be sufficiently satisfied.

  In addition, when the thermal transfer sheet kicked with the sublimation dye of the dye layer is rolled up on the back layer, the so-called back is formed in which the sublimation dye kicked on the back layer re-transfers to the dye layer, causing various problems. For example, in a thermal transfer sheet in which sublimation dye layers of different colors are repeatedly provided in the surface order on a substrate, the sublimation dye kicked to the back layer contains a sublimation dye having a hue different from that of the sublimation dye. When the dye layer is backed, the color development characteristics are deteriorated. 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.

JP 2012-66389 A

  The present invention has been made in view of such a situation, and even when the printing energy at the time of image formation is increased, the fusion between the dye layer and the receiving layer, and the sublimation dye of the dye layer. The main object is to provide a thermal transfer sheet that can effectively prevent the occurrence of a kick that moves to the back layer.

  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, wherein the dye layer includes at least It contains a sublimable dye, a binder resin, and a release agent, and the release agent contains a pentaerythritol fatty acid ester and / or a polyglycerin condensed ricinoleic acid ester.

  The dye layer may contain pentaerythritol fatty acid ester and / or polyglycerin condensed ricinoleic acid ester in a proportion of 0.1% by mass or more and 3% by mass or less with respect to the total solid content of the dye layer. Good.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the kick from which the dye of a dye layer transfers to a back layer can be effectively prevented, providing sufficient releasability to a dye 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. In the thermal transfer sheet 10 of the present invention, the dye layer 3 contains a sublimable dye, a binder resin, and a release agent, and the release agent is pentaerythritol fatty acid ester and / or polyglycerin condensed ricinoleate. It is characterized by including.

  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 back primer layer (not shown) is provided between the substrate 1 and the back layer 5. It may be done. 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 and the back surface primer layer are arbitrary structures in the thermal transfer sheet 10 of this 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 μm to 100 μm, preferably 1 μm to 10 μm.

(Dye layer)
As shown in the drawing, a dye layer 3 is provided on one surface of the substrate 1 (in the case shown in FIGS. 1 to 3, the upper surface of the substrate 1). The dye layer 3 is an essential component in the thermal transfer sheet 10 of the present invention.

  The dye layer 3 contains a sublimable dye, a binder resin, and a release agent. 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 containing sublimable dyes having different hues, such as yellow dye, magenta dye, and cyan dye, may be repeatedly formed on the same surface of the same substrate in the surface order. Hereinafter, each component contained in the dye layer 3 will be described.

<< Sublimation dye >>
The sublimable dye is not particularly limited, but a dye having a sufficient color density and not discolored by light, heat, temperature or the like is preferable. Examples of such sublimable dyes include diarylmethane dyes, triarylmethane dyes, thiazole dyes, merocyanine dyes, pyrazolone dyes, methine dyes, indoaniline dyes, acetophenone azomethine, pyrazoloazomethine, imidazole Azomethine dyes such as azomethine, imidazoazomethine and pyridone azomethine, xanthene dyes, oxazine dyes, cyanostyrene dyes such as dicyanostyrene and tricyanostyrene, thiazine dyes, azine dyes, acridine dyes, benzeneazo dyes, Pyridoneazo, thiophenazo, isothiazole azo, pyrrole azo, pyrazole azo, imidazole azo, thiadiazole azo, triazole azo, disazo azo dyes, spiropyran dyes, indolinospiro Run dyes, fluoran dyes, rhodamine lactam dyes, naphthoquinone dyes, anthraquinone dyes, quinophthalone dyes. 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. And blue dyes such as Solvent Blue 22.

  The content of the sublimable dye is preferably in the range of 50% by mass to 350% by mass, and more preferably in the range of 80% by mass to 300% by mass, based on the total solid content of the binder resin described later. preferable. If the content of the sublimable dye is less than the above range, the printing density may be lowered, and if it exceeds the above range, the storage stability and the like tend to be lowered.

<< Binder resin >>
The binder resin for supporting the sublimable dye is not particularly limited, and a resin having a certain degree of heat resistance and appropriate affinity with the sublimable dye can be used. Examples of such a binder resin include cellulose resins such as nitrocellulose, ethylcellulose, hydroxyethylcellulose, ethylhydroxycellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, and butyrate; polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl Examples thereof include vinyl resins such as acetoacetal and polyvinylpyrrolidone; acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide; polyurethane resins; polyamide resins; polyester resins;

  There is no particular limitation on the content of the binder resin, but when the content of the binder resin is less than 20% by mass with respect to the total solid content of the dye layer 3, the sublimable dye is sufficiently retained in the dye layer 3. It cannot be done, and the preservability tends to decrease. Therefore, the binder resin is preferably contained in an amount of 20% by mass or more based on the total solid content of the dye layer 3. There is no limitation in particular about the upper limit of content of binder resin, and it can set suitably according to content of a sublimation dye and the "specific mold release agent" mentioned later.

<< Releasing agent >>
The dye layer 3 contains a release agent together with the sublimation dye and the binder resin. In the present invention, the release agent contains either or both of a pentaerythritol fatty acid ester and a polyglycerol condensed ricinoleate. Features include points. That is, the dye layer 3 contains pentaerythritol fatty acid ester and / or polyglycerol condensed ricinoleic acid ester. Hereinafter, pentaerythritol fatty acid ester and polyglycerin condensed ricinoleic acid ester may be collectively referred to as “specific release agent”.

  According to the dye layer 3 containing the above-mentioned “specific release agent”, it is possible to impart high releasability to the dye layer 3, and in order to cope with speeding up of the printer, the printing energy at the time of image formation Even when the height is increased, it is possible to prevent the thermal transfer image-receiving sheet from being fused with the receiving layer. Although the mechanism by which the “specific release agent” is excellent in the release property of the dye layer 3 is not clear at present, the “specific release agent” contributes to the improvement of the release property of the dye layer 3. This is clarified by the results of Examples described later.

  The dye layer 3 may contain a “specific release agent” having a melting point of 25 ° C. or less, or may contain a “specific release agent” exceeding 25 ° C. In addition, both a “specific release agent” having a melting point of 25 ° C. or less and a “specific release agent” having a melting point of more than 25 ° C. may be contained. The melting point of “specific release agent” means a melting point measured according to JIS K 0064 (1992). In other words, the “specific release agent” contained in the dye layer 3 may exist in a liquid state or may exist in a solid state. The “specific release agent” can satisfy both the release property and the preservability of the dye layer 3 irrespective of the state of existence thereof, but mainly aims to further improve the release property of the dye layer 3. In this case, the dye layer 3 preferably contains a “specific release agent” having a melting point of 25 ° C. or lower. On the other hand, when the main purpose is to further improve the storage stability of the dye layer 3, the dye layer 3 preferably contains a "specific release agent" having a melting point exceeding 25 ° C.

  In particular, the “specific release agent” having a melting point of 25 ° C. or lower can form a high-quality image with no roughness or very little roughness, in addition to the above-described improvement in mold releasability and storage stability. Is preferable. When the dye layer 3 contains a “specific release agent” having a melting point exceeding 25 ° C., that is, when the solid “specific release agent” is contained in the dye layer, the solid layer The “specific release agent” protrudes from the surface of the dye layer 3, and depending on the particle size of the “specific release agent” and the content thereof, roughness due to the protruding release agent tends to occur. It is in. Therefore, when considering the roughness of the image, use a “specific release agent” having a melting point of 25 ° C. or lower, or the particle size and content of the “specific release agent” having a melting point of more than 25 ° C. Is preferably adjusted as appropriate.

  In addition, in the present invention, in addition to the improvement of the releasability by the “specific release agent”, the effect of preventing the occurrence of kick in which the sublimable dye contained in the dye layer 3 moves to the back layer 5 is achieved. It has been. The effect of preventing the occurrence of kicking is presumed to be due to the fact that the above-mentioned “specific release agent” does not adversely affect the storage stability of the sublimable dye in the dye layer 3. Due to this property, even if the content of the “specific release agent” in the dye layer 3 is increased to some extent, it causes a decrease in storage stability, which is a harmful effect of including the release agent. Therefore, it is possible to simultaneously satisfy the improvement in releasability and the effect of preventing the occurrence of kick. That is, in the present invention, by including a “specific release agent” in the dye layer 3, it is possible to satisfy both the improvement in releasability and the improvement in storage stability, which are in a trade-off relationship.

  In addition, conventionally known liquid release agents such as silicone oil and phosphate esters are release agents that cause a decrease in the storage stability of the dye layer. In order to sufficiently satisfy the release agents, these release agents are used. When the content of the mold is increased, the storability of the dye layer 3 is lowered as a detrimental effect, and the occurrence of kick cannot be prevented. On the other hand, conventionally known solid mold release agents, such as metal soaps and polyethylene waxes, are superior in storage stability than previously known liquid mold release agents, but sufficiently satisfy the mold release properties. Can not. Further, in order to satisfy the mold release property by the solid mold release agent, it is necessary to increase the content of the solid mold release agent in the dye layer. However, like the liquid mold release agent, the solid mold release agent is required. Even if it is an agent, its preservability decreases as its content increases. Further, even when a conventionally known liquid mold release agent and a conventionally known solid mold release agent are used in combination, the mold release property and the storage stability cannot be sufficiently satisfied.

  Further, according to the thermal transfer sheet 10 of the present invention, it is possible to form a high quality image by preventing the occurrence of the kick. For example, as shown in FIG. 3, in a thermal transfer sheet including a plurality of dye layers 3 containing sublimable dyes having different hues, when a sublimation dye (for example, yellow (Y) dye) is kicked to the back layer, thermal transfer is performed. When the sheet is rewound, the sublimation dye kicked back to another dye layer (for example, cyan (C) dye) containing a sublimation dye having a different hue from the sublimation dye, and another dye layer ( For example, the image quality is deteriorated during image formation using a cyan (C) dye layer. In the present invention, since the occurrence of kick is prevented in the dye layer 3 as described above, even when the thermal transfer sheet is provided with a plurality of dye layers having different hues, the deterioration of the image quality is prevented. be able to. As shown in FIG. 3, in the thermal transfer sheet including a plurality of dye layers containing sublimable dyes having different hues, one dye layer of the plurality of dye layers contains the above-mentioned “specific release agent”. However, it is preferable that two or more dye layers or all the dye layers contain the above-mentioned “specific release agent”. Hereinafter, specific examples of pentaerythritol fatty acid ester and polyglycerin condensed ricinoleic acid ester will be described.

<Pentaerythritol fatty acid ester>
As shown in the following general formula (1), pentaerythritol fatty acid ester is composed of pentaerythritol represented by the following general formula (2) and a fatty acid represented by “R′COOH” (general formula (3)). The pentaerythritol fatty acid ester is an ester, and includes a linear or branched fatty acid residue. The fatty acid residue referred to in the present specification means “R′CO” in the fatty acid of the general formula (3), and “R ′” in the general formula (3) is an alkyl group and / or alkenyl. It is a group.

The pentaerythritol fatty acid ester is not particularly limited as long as it exhibits the structure represented by the general formula (1), and one of R ^{1 to} R ⁴ in the general formula (1) is a fatty acid residue. Good.

  The fatty acid residue contained in the pentaerythritol fatty acid ester is not particularly limited. Examples of the fatty acid residue include lauric acid residue, palmitic acid residue, stearic acid residue, isostearic acid residue, oleic acid residue, and capryl. Examples include acid residues, myristic acid residues, behenic acid residues and the like.

  Specific examples of the pentaerythritol fatty acid ester include pentaerythritol monooleate, pentaerythritol distearate, pentaerythritol tetraoleate, pentaerythritol tetrastearate, pentaerythritol (adipic acid / oleic acid). Mention may be made of mixed esters and pentaerythritol (adipic acid / stearic acid) mixed esters.

  As the pentaerythritol fatty acid ester, a commercially available product can be used as it is, and examples of the commercially available product include EW600B of Riken Vitamin Co., Ltd., Unistar H-482R and Nistar H-476 of NOF Corporation. Can do.

<Polyglycerin condensed ricinoleic acid ester>
The polyglycerin condensed ricinoleic acid ester is an ester of condensed ricinoleic acid and polyglycerin. The condensed ricinoleic acid can be obtained by a conventionally known method such as an intramolecular dehydration condensation reaction of ricinoleic acid.

  Specific examples of the polyglycerin condensed ricinoleic acid ester include glycerin condensed ricinoleic acid ester, tetraglycerin condensed ricinoleic acid ester, hexaglycerin condensed ricinoleic acid ester, and decaglycerin condensed ricinol ester.

  As the polyglycerin condensed ricinoleic acid ester, a commercially available product can be used as it is. Examples of commercially available products include CR-310, CR-500, CR-ED, CRS-75, Nikko Chemicals (Sakamoto Pharmaceutical Co., Ltd.) NIKKOL Hexaglyn PR-15, NIKKOL Decaglyn PR-20, and Poem PR-100 and Poem PR-300 of Riken Vitamin Co., Ltd.

  The content of the “specific release agent” with respect to the total solid content of the dye layer 3 is not particularly limited, but the content of the “specific release agent” with respect to the total solid content of the dye layer 3 is 0.1% by mass. If it is less than the range, the effect of improving the releasability caused by the “specific release agent” tends to decrease. On the other hand, when the content of the “specific release agent” exceeds 3% by mass, the preservability of the dye layer 3 tends to decrease. Therefore, considering this point, the content of the “specific release agent” with respect to the total solid content of the dye layer 3 is preferably in the range of 0.1% by mass to 3% by mass. Even if the content of the “specific release agent” is outside this range, according to the dye layer 3 containing the “specific release agent”, a conventionally known liquid or solid release agent is used. It is possible to simultaneously improve the releasability and the storage stability which cannot be satisfied by a dye layer containing an agent.

  The dye layer 3 may contain only one of pentaerythritol fatty acid ester and polyglycerin condensed ricinoleic acid ester, or both of them. The preferable content in the case where both are contained is based on the total amount of both.

  Further, if the condition that the “specific release agent” is contained in the dye layer 3 is satisfied, the dye layer 3 may contain other release agents. For example, a release agent other than pentaerythritol fatty acid ester or polyglycerin condensed ricinoleic acid ester may be contained together with “specific release agent”.

  In addition, when other arbitrary mold release agents are contained in the dye layer 3 together with the “specific mold release agent”, all mold release agents contained in the dye layer 3 and including the “specific mold release agent” are used. The content of the “specific release agent” with respect to the total amount of the agent is preferably 70% by mass or more. When the content is less than 70% by mass, the storage stability may be lowered or the release property may not be sufficiently improved due to any other release agent.

  If desired, the dye layer 3 may contain additives such as inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include carbon black, aluminum, and molybdenum disulfide. Examples of the organic fine particles include polyethylene wax.

  The method for forming the dye layer 3 is not particularly limited, and the sublimable dye, binder resin, “specific release agent” described above, and other optional components added as necessary are dispersed in an appropriate solvent. The dissolved dye layer coating solution is applied onto the substrate 1 by a conventionally known coating means such as a gravure printing method, a reverse roll coating method using a gravure plate, a roll coater or a bar coater, and then dried. Can be formed.

Although there is no particular limitation on the thickness of the dye layer 3 is preferably coated amount after drying is 0.3g / m ² ~1.5g / m ² approximately.

(Back layer)
A back layer 5 is provided on the other surface of the substrate 1. There is no limitation in particular about binder resin which comprises the back layer 5, A conventionally well-known thermoplastic resin etc. can be selected suitably and can be formed. Examples of the thermoplastic resin include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyethylene resins, polypropylene resins, and other polyolefin resins, polystyrene resins. Polyvinyl acetal resins such as polyvinyl chloride resins, polyether resins, polyamide resins, polyimide resins, polyamide imide resins, polycarbonate resins, polyacrylamide resins, polyvinyl chloride resins, polyvinyl butyral resins, polyvinyl acetoacetal resins And the like, and these silicone-modified products.

  Moreover, it is preferable that the back surface layer 5 contains a lubricant for improving slipperiness with the thermal head. The lubricant is an arbitrary configuration in the back layer 5. Examples of the lubricant include phosphoric acid esters, fatty acid esters, metal soaps, Wax, graphite powder, fluorine-modified graft polymers, fluorine-modified block polymers, silicone oils, silicone-modified graft polymers, silicone polymers such as silicone-modified block polymers, and the like. It can be appropriately selected and used. Among the above-mentioned lubricant components, phosphate ester, fatty acid ester, metal soap, and Wax can be particularly preferably used in the present invention.

  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, and known additives for plastics can be used. In the present invention, zinc stearate and / or zinc stearyl phosphate can be preferably used.

  Examples of the phosphate ester include (1) a phosphoric acid monoester or diester of a saturated or unsaturated higher alcohol having 6 to 20 carbon atoms, and (2) a phosphoric acid monoester of a polyoxyalkylene alkyl ether or polyoxyalkylene alkyl allyl ether. Ester or diester, (3) phosphoric acid monoester or diester of the above-mentioned saturated or unsaturated higher alcohol alkylene oxide adduct (average number of added moles 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 (3) include nonylphenol, dodecylphenol, diphenylphenol and the like.

The method for forming the back layer 5 is not particularly limited, and a back layer coating solution prepared by dissolving or dispersing a binder resin and, if necessary, a lubricant added in a suitable solvent is used for gravure printing, screen printing, gravure. It can form by apply | coating on the base material 1 using well-known coating means, such as the reverse roll coating method using a plate, and drying. Examples of the solvent used for preparing the coating liquid include water, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, dimethylformamide, ethyl acetate, butyl acetate, ethylene glycol, dimethylacetamide, Examples thereof include dimethyl sulfoxide. The coating amount of the back layer coating solution, from the viewpoint of improvement of such as heat resistance, is preferably 3 g / m ² or less, and more preferably about 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 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 its 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 .

  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 a base material, and a coating solution for the back layer having the following composition was applied to one surface of the base material, and the coating amount upon drying was 1.0 g / m ^2. Then, coating was performed using a bar coater and dried at 100 ° C. for 1 minute to form a back layer. Also, apply the dye layer coating solution 1 having the following composition on the other surface (easy adhesion-treated surface) of the substrate using a bar coater so that the coating amount upon drying is 0.6 g / m ^2. The thermal transfer sheet of Example 1 was obtained by processing and forming a dye layer.

<Back layer coating liquid>
・ 60 parts of polyvinyl acetal resin (SREC KS-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate (solid content 75%) 26.7 parts (Bernock D-750 DIC Corporation)
-Zinc stearyl phosphate 8 parts (LBT-1830 purification Sakai Chemical Industry Co., Ltd.)
・ Zinc stearate 8 parts (SZ-PF Sakai Chemical Industry Co., Ltd.)
・ Talc 4 parts (Microace P-3 Nippon Talc Industry Co., Ltd.)
・ Methyl ethyl ketone 450 parts ・ Toluene 450 parts

<Dye layer coating solution 1>
・ Solvent Blue 63 (cyan dye) 69.9 parts ・ Polyvinylacetoacetal resin 30.0 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Pentaerythritol (adipic acid / oleic acid) ester 0.1 part (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 2>
・ Solvent Blue 63 (cyan dye) 69.8 parts ・ Polyvinylacetoacetal resin 29.9 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Pentaerythritol (adipic acid / oleic acid) ester 0.3 part (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 3>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
-Pentaerythritol (adipic acid / oleic acid) ester 1.0 part (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 4>
・ Solvent Blue 63 (cyan dye) 67.9 parts ・ Polyvinylacetoacetal resin 29.1 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Pentaerythritol (adipic acid / oleic acid) ester 3.0 parts (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 5>
・ Solvent Blue 63 (cyan dye) 67.2 parts ・ Polyvinylacetoacetal resin 28.8 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Pentaerythritol (adipic acid / oleic acid) ester 4.0 parts (Ricester EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating liquid 6>
Solvent Blue 63 (cyan dye) 69.3 parts Nitrocellulose resin 29.7 parts (DHM 10-25 Inabata Sangyo Co., Ltd.)
-Pentaerythritol (adipic acid / oleic acid) ester 1.0 part (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 7>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Pentaerythritol oleate 1.0 part (Unistar H-481R NOF Corporation)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 8>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5, Sekisui Chemical Co., Ltd.)
-Pentaerythritol stearate 1.0 part (Unistar H-476 NOF Corporation)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 9>
・ Solvent Blue 63 (cyan dye) 69.8 parts ・ Polyvinylacetoacetal resin 29.9 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Hexaglycerin condensed ricinoleate 0.3 parts (Poem PR-300, RIKEN VITAMIN Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 10>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
-Hexaglycerin condensed ricinoleate 1.0 part (Poem PR-300 RIKEN VITAMIN Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 11>
・ Solvent Blue 63 (cyan dye) 67.9 parts ・ Polyvinylacetoacetal resin 29.1 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
-Hexaglycerin condensed ricinoleate 3.0 parts (Poem PR-300 RIKEN VITAMIN Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating liquid 12>
Solvent Blue 63 (cyan dye) 69.3 parts Nitrocellulose resin 29.7 parts (DHM 10-25 Inabata Sangyo Co., Ltd.)
-Hexaglycerin condensed ricinoleate 1.0 part (Poem PR-300 RIKEN VITAMIN Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 13>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Decaglycerin condensed ricinoleic acid ester 1.0 part (NIKKOL DecaglynPR-20 Nikko Chemicals Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 14>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
Tetraglycerin condensed ricinoleate 1.0 part (SY Glyster CR-310 Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating solution 15>
・ Solvent Blue 63 (cyan dye) 69.1 parts ・ Polyvinylacetoacetal resin 29.6 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
-Pentaerythritol (adipic acid / oleic acid) ester 1.0 part (Rikestar EW600B Riken Vitamin Co., Ltd.)
・ Polyether-modified silicone oil 0.3 parts (FZ2101 Toray Dow Corning Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 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 dye layer coating liquid A having the following composition was used instead of the dye layer coating liquid 1.

<Dye layer coating liquid A>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
-Polyether-modified silicone oil 1.0 part (FZ2101 Toray Dow Corning Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating liquid B>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ 1.0 parts of fluorinated oligomer (Megafac F-552F DIC Corporation)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating liquid C>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Phosphate ester 1.0 part (Pricesurf A208S Daiichi Kogyo Seiyaku Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

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

<Dye layer coating liquid D>
・ Solvent Blue 63 (cyan dye) 69.3 parts ・ Polyvinylacetoacetal resin 29.7 parts (ESREC KS-5 Sekisui Chemical Co., Ltd.)
・ Decaglycerin decastearic acid ester 1.0 part (NIKKOL Decaglyn 10-SV Nikko Chemicals Co., Ltd.)
・ Methyl ethyl ketone 500 parts ・ Toluene 500 parts

(Evaluation of releasability)
The thermal transfer sheet of each example and comparative example was cut and pasted on the cyan portion of a genuine ink ribbon of a sublimation thermal transfer printer (manufactured by ALTECH ADS, model: CW-01), and the thermal transfer image receiving sheet dedicated to the printer After the printer was warmed to 35 ° C., a black solid image (255/255 gradations) was printed on the thermal transfer image-receiving sheet, and sensory evaluation of peeling sound generated at that time and the obtained printed matter It was confirmed by visual observation whether or not there was a peeling mark, and the releasability was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1.

"Evaluation criteria"
A: No peeling noise is generated, and there is no peeling mark on the printed material.
○ ... Slight peeling noise is generated, but there is no peeling mark on the printed matter and there is no problem in actual use.
X: Peeling sound is generated, and the printed matter has a peeling mark.

(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
Incidentally, L ^* a ^* b ^* means CIE1976, L ^* a ^* b ^* defined in the color system ^{(JIS Z8729 1980) L * a} * b *.

"Evaluation criteria"
A: Color difference ΔE ^* is less than 2.5 B: 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 ^* Is 5.0 or more

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

Claims (2)

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 dye layer contains at least a sublimable dye, a binder resin, and a release agent,
The thermal transfer sheet, wherein the release agent contains pentaerythritol fatty acid ester and / or polyglycerin condensed ricinoleic acid ester.   The dye layer contains pentaerythritol fatty acid ester and / or polyglycerin condensed ricinoleic acid ester in a proportion of 0.1% by mass or more and 3% by mass or less with respect to the total solid content of the dye layer. The thermal transfer sheet according to claim 1.

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