JP2020055180A - Thermal transfer sheet - Google Patents

Abstract

To provide a thermal transfer sheet capable of producing a printed matter having high glossiness and plasticizer resistance.SOLUTION: A thermal transfer sheet includes a base material and a transfer layer. The transfer layer includes a release layer containing a styrene-(meth)acrylic copolymer, and a plasticizer resistance layer containing a metal oxide and a resin material. A development area ratio (Sdr) of a boundary face is 0.5 or less at an opposite surface to a surface where a release layer is provided on the plasticizer resistance layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal transfer sheet.

  Conventionally, a thermal transfer sheet having a dye layer containing a sublimable dye and a transfer target are superimposed on each other, and then the thermal transfer sheet is heated by a thermal head provided in a thermal transfer printer, whereby the sublimable dye in the dye layer is heated. There is known a sublimation type thermal transfer system in which an image is formed by transferring an image to a transfer target and forming an image.

Further, for the purpose of improving the durability and the like of the printed matter produced by the sublimation transfer method, the printed matter and a thermal transfer sheet having a transfer layer are overlapped, and then the thermal transfer sheet is heated by a thermal head provided in the thermal transfer printer. By doing so, a transfer layer is transferred onto an image formed on a print.
Further, a thermal transfer sheet provided with a dye layer and a transfer layer in a plane-sequential manner is also widely known (Patent Document 1).

  In recent years, prints have been required to have various appearances according to their uses and the like. For example, in order to impart a high-grade feeling to prints, a transfer layer to be transferred may be required to have high gloss.

  For example, Patent Literature 2 proposes a thermal transfer sheet including a release layer containing a styrene- (meth) acrylic copolymer as a transfer layer.

JP 2018-051914 A JP 2012-035448 A

Recently, the present inventors have found that a printed matter produced using a thermal transfer sheet provided with a release layer containing a styrene- (meth) acrylic copolymer disclosed in Patent Document 2 has high glossiness. It was found that the plasticizer resistance was not sufficient and there was room for improvement.
The present inventors have found that by providing a layer containing a metal oxide and a resin material and having a developed area ratio (Sdr) in a specific numerical range on the release layer, the plasticizer resistance can be significantly improved. I found it.

  Accordingly, an object of the present invention is to provide a thermal transfer sheet capable of producing a printed matter having high gloss and plasticizer resistance.

The thermal transfer sheet of the present invention includes a substrate and a transfer layer,
The transfer layer includes a release layer containing a styrene- (meth) acrylic copolymer, and a plasticizer layer containing a metal oxide and a resin material,
The development area ratio (Sdr) of the interface on the surface opposite to the surface on which the release layer of the plasticizer layer is provided is 0.5 or less.

  In one embodiment, the plasticizer-resistant layer contains at least one of aluminum oxide and silicon oxide as the metal oxide.

  In one embodiment, the content of the metal oxide in the plasticizer-resistant layer is from 20% by mass to 90% by mass.

  In one embodiment, the resin material contained in the plasticizer layer is a vinyl resin.

  In one embodiment, the content of the resin material in the plasticizer-resistant layer is from 10% by mass to 80% by mass.

  In one embodiment, the transfer layer further comprises an adhesive layer on the plasticizer-resistant layer.

In one embodiment, the thermal transfer sheet of the present invention includes a primer layer and a dye layer formed on the primer layer so that the transfer layer is surface-sequential,
The primer layer and the plasticizer-resistant layer are formed of the same material.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal transfer sheet which can manufacture the printed material which has high glossiness and plasticizer resistance can be provided.

FIG. 1 is a schematic sectional view illustrating an embodiment of a thermal transfer sheet of the present invention. FIG. 1 is a schematic sectional view illustrating an embodiment of a thermal transfer sheet of the present invention. FIG. 1 is a schematic sectional view illustrating an embodiment of a thermal transfer sheet of the present invention. FIG. 1 is a schematic sectional view illustrating an embodiment of a thermal transfer sheet of the present invention.

(Thermal transfer sheet)
As shown in FIG. 1, the thermal transfer sheet 10 according to the present invention includes a base material 11 and a transfer layer 12, and the transfer layer includes a release layer 13 and a plasticizer layer 14.
In one embodiment, the transfer layer 12 further includes an adhesive layer 15 on the plasticizer-resistant layer 14, as shown in FIG.
Further, in one embodiment, the thermal transfer sheet 10 according to the present invention includes a primer layer 16 and a dye layer 17 on the base material 11 so as to be surface-sequential with the transfer layer 12, as shown in FIG. Further, FIG. 3 shows a thermal transfer sheet provided with a plurality of dye layers, but may be a mode provided with only one dye layer. Although the thermal transfer sheet provided with a plurality of primer layers has been described, the plurality of primer layers may be a continuous mode formed in a single step.
In one embodiment, the thermal transfer sheet 10 according to the present invention includes a back layer 18 on the surface of the substrate 11 opposite to the surface on which the transfer layer 12 is provided, as shown in FIG.
Further, in one embodiment, the thermal transfer sheet of the present invention can include a release layer between the base material and the transfer layer (not shown).
Hereinafter, each layer included in the thermal transfer sheet according to the present invention will be described.

(Base material)
The substrate has heat resistance enough to withstand the heat energy applied at the time of thermal transfer, and can be used without any particular limitation as long as it has mechanical strength and melting material resistance capable of supporting a transfer layer and the like provided on the substrate. .

As the base material, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), 1,4-polycyclohexylene dimethylene terephthalate, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, etc. Polyester such as polyester, nylon 6 and nylon 6,6, polyolefin such as polyethylene (PE), polypropylene (PP) and polymethylpentene, polyvinyl chloride, polyvinyl alcohol (PVA), polyvinyl acetate, vinyl chloride-vinyl acetate Copolymers, vinyl resins such as polyvinyl butyral and polyvinyl pyrrolidone (PVP), (meth) acrylic resins, imide resins such as polyimide and polyetherimide, cellophane, cellulose acetate Nitrocellulose, cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) and other cellulose resins, polystyrene (PS) and other styrene resins, polycarbonates, ionomer resins and other films (hereinafter simply referred to as "Resin film") can be used.
Among the above-mentioned resins, polyesters such as PET and PEN are preferred from the viewpoint of heat resistance and mechanical strength, and PET is particularly preferred.
In the present invention, “(meth) acryl” means to include both “acryl” and “methacryl”.

  Further, a laminate of the above resin films can be used as a substrate. The laminated body of the resin film can be manufactured by using a dry lamination method, a wet lamination method, an extrusion method, or the like.

  When the substrate is a resin film, the resin film may be a stretched film or an unstretched film, but from the viewpoint of strength, a stretched film stretched in a uniaxial or biaxial direction. It is preferred to use.

  The thickness of the substrate is preferably 2 μm or more and 25 μm or less, more preferably 3 μm or more and 10 μm or less. Thereby, the mechanical strength of the substrate can be improved.

(Transfer layer)
The transfer layer included in the thermal transfer sheet of the present invention includes at least a release layer and a plasticizer layer. In one embodiment, the transfer layer includes an adhesive layer on the plasticizer-resistant layer.

(Release layer)
The release layer contains a styrene- (meth) acrylic copolymer, whereby the glossiness of a print produced using the thermal transfer sheet of the present invention can be improved (hereinafter, simply referred to as glossiness). Further, the transferability of the transfer layer (hereinafter, simply referred to as transferability) and the transparency of the release layer can be improved (hereinafter, simply referred to as transparency).
In the present invention, the styrene- (meth) acrylic copolymer is a copolymer of a styrene monomer and a (meth) acrylic acid monomer or a (meth) acrylic acid ester monomer.
Examples of the styrene monomer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, propylstyrene, fluorostyrene, chlorostyrene, bromostyrene, nitrostyrene, and methoxystyrene.
(Meth) acrylic acid monomer and (meth) acrylic acid ester monomer include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. Octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate.

  As long as the properties of the present invention are not impaired, the styrene- (meth) acrylic copolymer may contain a monomer other than a styrene monomer, a (meth) acrylic acid monomer and a (meth) acrylic acid ester monomer. The content is preferably at most 10 mol%, more preferably at most 5 mol%, even more preferably at most 3 mol%, based on all constitutional units.

  The content of the styrene- (meth) acryl copolymer in the release layer is preferably from 70% by mass to 100% by mass, more preferably from 90% by mass to 100% by mass. Thereby, glossiness, transferability, and transparency can be further improved.

  In one embodiment, the release layer is a natural wax such as beeswax, spermaceti, wood wax, rice bran wax, carnauba wax, candelilla wax and montan wax, paraffin wax, microcrystalline wax, oxidized wax, ozokerite, ceresin, ester wax and Synthetic waxes such as polyethylene wax, higher saturated fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, phloic acid and behenic acid, higher saturated monohydric alcohols such as stearyl alcohol and behenyl alcohol, fatty acid esters of sorbitan, etc. And waxes such as higher fatty acid amides such as stearamide and oleic amide. Thereby, transferability can be further improved.

  The content of the wax in the release layer is preferably from 0.1% by mass to 5% by mass, and more preferably from 0.3% by mass to 3% by mass. Thereby, transferability can be further improved.

  As long as the properties of the present invention are not impaired, the release layer may contain a resin material other than the styrene- (meth) acrylic copolymer, and may include polyester, polyamide, polyolefin, vinyl resin, (meth) acrylic resin, and imide resin. , A cellulose resin, a styrene resin, a polycarbonate, and an ionomer resin.

  Further, as long as the properties of the present invention are not impaired, the release layer may be a release material, a plasticizer, a filler, an ultraviolet light stabilizer, a coloring prevention material, a surfactant, a fluorescent whitening material, a matting material, a deodorant material. It may contain additives such as flame retardant, weather resistant, antistatic, yarn friction reducing, slip, antioxidant, ion exchange, dispersing, ultraviolet absorbing and coloring materials such as pigments and dyes. it can.

  The thickness of the release layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 0.8 μm or more and 2 μm or less. Thereby, glossiness and transferability can be further improved.

  The release layer is obtained by dispersing or dissolving the above material in water or a suitable solvent, and applying a known method such as a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, and a rod coating method. It can be formed by applying a film on a substrate to form a coating film and drying the coating film.

(Plasticizer layer)
The development area ratio (Sdr) on the surface opposite to the surface on which the release layer of the plasticizer layer is provided is 0.5 or less. As a result, the plasticizer resistance of a print produced using the thermal transfer sheet of the present invention can be improved (hereinafter, simply referred to as plasticizer resistance).
In the present invention, the “expanded area ratio (Sdr)” is defined in ISO 25178 and indicates how much the expanded area (surface area) of the defined area has increased with respect to the area of the defined area. It is.
In the present invention, the developed area ratio (Sdr) of the plasticizer-resistant layer is measured by a laser microscope (manufactured by KEYENCE CORPORATION, measuring unit VK-X160, controller VK-X150, magnification of 240 times) and an analysis application. .
When the thermal transfer sheet of the present invention has an adhesive layer on the plasticizer-resistant layer, the measurement is performed after wiping and removing the adhesive layer using a mixed solution of methyl ethyl ketone and toluene or the like.
The development area ratio (Sdr) of the plasticizer-resistant layer can be adjusted by adjusting the composition of the plasticizer-resistant layer and the pH of the coating solution used for forming the plasticizer-resistant layer.

  The plasticizer-resistant layer contains a metal oxide, and examples thereof include aluminum oxide (alumina), silicon oxide (silica), titanium oxide, zirconium oxide, tin oxide, and magnesium oxide. Among these, aluminum oxide and silicon oxide are preferable from the viewpoint of plasticizer resistance.

The average particle size of the metal oxide is preferably 100 nm or less, more preferably 3 nm or more and 30 nm or less. Thereby, the plasticizer resistance can be further improved while maintaining the transparency.
In the present invention, the average particle size of the metal oxide is measured using an electron microscope or the like.

  The shape of the metal oxide is not particularly limited, and examples thereof include a sphere, an ellipse, a column, and a prism.

  The content of the metal oxide in the plasticizer-resistant layer is preferably from 20% by mass to 90% by mass, and more preferably from 50% by mass to 80% by mass. Thereby, the plasticizer resistance can be further improved while maintaining the transparency.

  The plasticizer-resistant layer contains at least one resin material, and examples thereof include polyester, polyamide, polyolefin, vinyl resin, (meth) acrylic resin, imide resin, cellulose resin, styrene resin, polycarbonate, and ionomer resin. Among these, from the viewpoint of plasticizer resistance and transparency, a vinyl resin is preferable, and PVP is particularly preferable.

  The content of the resin material in the plasticizer layer is preferably from 10% by mass to 80% by mass, and more preferably from 20% by mass to 50% by mass. Thereby, the plasticizer resistance can be further improved.

  The plasticizer-resistant layer may contain the above-mentioned additive within a range that does not impair the characteristics of the present invention.

  The thickness of the plasticizer-resistant layer is preferably from 0.02 μm to 1 μm, and more preferably from 0.03 μm to 0.5 μm. Thereby, the plasticizer resistance can be further improved.

The plasticizer-resistant layer is formed by dispersing or dissolving the above material in an appropriate water, solvent, or solution to prepare a coating solution, and using a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, or a bar coating method. It can be formed by applying a known method such as a rod coating method or the like on the release layer to form a coating film and drying the coating film.
It is preferable that the pH of the coating liquid is appropriately adjusted according to the material to be dispersed or dissolved.
When aluminum oxide is used as the metal oxide, the coating liquid preferably contains a solution having a pH of 1 to 3 (eg, hydrochloric acid).
When silicon oxide is used as the metal oxide, the coating liquid preferably contains water or a solution having a pH of 5 or more and 7 or less.
In addition, as the water, ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or the like can be used.
Further, the coating liquid preferably further contains isopropanol (IPA) in addition to a solution having a pH of 1 to 3 or a solution having a pH of 5 to 7 or less.
In this case, the ratio between the content of the solution having a pH of 1 to 3 or the content of water or a solution having a pH of 5 to 7 and the content of the IPA is (the solution of the solution having a pH of 1 to 3 or the solution of water or the solution having a pH of 5 to 7 or less). (Content / IPA content), preferably 1/3 or more and 3/1 or less.

(Adhesive layer)
In one embodiment, the adhesive layer includes at least one type of thermoplastic resin that softens when heated and exhibits adhesion.
As the thermoplastic resin, for example, polyester, vinyl resin such as ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, (meth) acrylic resin, (meth) acrylic resin, polyurethane, cellulose resin, polyamide, Examples include polyolefin, styrene resin, and chlorinated resins thereof.

  The content of the thermoplastic resin in the adhesive layer is not particularly limited, but is, for example, preferably 50% by mass or more, and more preferably 60% by mass or more. Thereby, the adhesiveness of the adhesive layer to the transfer object can be improved.

  The adhesive layer may contain the above-mentioned additive within a range that does not impair the characteristics of the present invention.

  The thickness of the adhesive layer is not particularly limited, but may be, for example, 0.05 μm or more and 0.5 μm or less. Thereby, the adhesiveness of the adhesive layer to the transfer object can be improved.

  The adhesive layer is obtained by dispersing or dissolving the above material in water or a suitable solvent, and applying a known method such as a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, and a rod coating method. It can be formed by applying a coating on the plasticizer-resistant layer to form a coating film and drying the coating film.

(Primer layer)
In one embodiment, the thermal transfer sheet of the present invention includes a primer layer between the substrate and the dye layer. Thereby, the dye layer holding property of the thermal transfer sheet can be improved (hereinafter, simply referred to as dye layer holding property).

  The primer layer contains at least one resin material. The resin material is not particularly limited as long as it can improve the adhesion between the base material and the dye layer, and examples thereof include polyester, polyamide, polyolefin, vinyl resin, (meth) acrylic resin, and imide resin. Examples include cellulose resin, styrene resin, polycarbonate, and ionomer resin.

  The content of the resin material in the primer layer is preferably 10% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 50% by mass or less. Thereby, the dye layer retention can be further improved.

  The primer layer can include the above metal oxide. Thereby, the adhesion between the substrate and the dye layer can be further improved. Further, transfer of the dye to the primer layer and the substrate can be prevented, and the density of an image formed using the thermal transfer sheet of the present invention can be improved.

  The average particle size of the metal oxide is preferably 100 nm or less, more preferably 3 nm or more and 30 nm or less. Thereby, the adhesion between the substrate and the dye layer can be further improved, and the density of the formed image can be further improved.

  The shape of the metal oxide is not particularly limited, and examples thereof include a sphere, an ellipse, a column, and a prism.

  The content of the metal oxide in the primer layer is preferably 20% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 80% by mass or less. Thereby, the adhesion between the substrate and the dye layer can be further improved, and the density of the formed image can be further improved.

  As long as the characteristics of the present invention are not impaired, the primer layer may contain the above-mentioned additive.

  The thickness of the primer layer is preferably from 0.02 μm to 1 μm, and more preferably from 0.03 μm to 0.5 μm. Thereby, the adhesion between the substrate and the dye layer can be further improved, and the density of the formed image can be further improved.

The primer layer is obtained by dispersing or dissolving the above materials in water or a suitable solvent to prepare a coating solution, and using a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, a rod coating method, or the like. By coating on a base material to form a coating film and drying the coating film by a known means described above.
In the present invention, the primer layer and the plasticizer layer can be formed of the same material. That is, the coating liquid used for forming the plasticizer-resistant layer can be used for forming the primer layer. Thereby, the manufacturing process can be omitted and the material cost can be reduced.
More specifically, after forming a release layer on the substrate, by applying a primer layer forming coating liquid on the substrate and the release layer, by drying, to form a primer layer on the substrate, The formation of the plasticizer-resistant layer on the release layer can be performed simultaneously.

(Dye layer)
In one embodiment, the thermal transfer sheet of the present invention includes a dye layer on the primer layer. The dye layer contains a sublimable dye, for example, diarylmethane dye, triarylmethane dye, thiazole dye, merocyanine dye, pyrazolone dye, methine dye, indoaniline dye, acetophenone azomethine dye, pyrazoloazomethine dye, xanthene dye, oxazine Dyes, thiazine dyes, azine dyes, acridine dyes, azo dyes, spiropyran dyes, indolinospiropyran dyes, fluorane dyes, naphthoquinone dyes, anthraquinone dyes and quinophthalone dyes are exemplified.

  The dye layer contains a resin material, and the resin material is not particularly limited as long as it can support the above-described sublimation dye. For example, (meth) acrylic resin, polyester, polyamide, vinyl resin, imide resin And cellulose resin.

  Further, the dye layer may include the above-mentioned additive.

  The thickness of the dye layer is not particularly limited, and can be, for example, 0.2 μm or more and 5 μm or less.

  The dye layer is obtained by dispersing or dissolving the above material in water or a suitable solvent, and applying a known method such as a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, and a rod coating method. It can be formed by applying a coating on the primer layer to form a coating film and drying the coating film.

(Back layer)
In one embodiment, the thermal transfer sheet of the present invention includes a back layer on the side of the substrate on which the transfer layer is not provided. Thereby, it is possible to prevent sticking and wrinkles from being generated due to heating during thermal transfer.

  In one embodiment, the back layer includes a resin material, and examples thereof include a cellulose resin, a styrene resin, a vinyl resin, a polyester, a polyurethane, a silicone-modified polyurethane, a fluorine-modified polyurethane, and a (meth) acrylic resin.

  In one embodiment, the back layer contains, as a resin material, a two-part curable resin that is cured in combination with an isocyanate compound or the like. Examples of such a resin include polyvinyl acetal such as polyvinyl acetoacetal and polyvinyl butyral.

  In one embodiment, the back layer includes inorganic or organic particles. This can more effectively prevent the occurrence of sticking and wrinkles due to heating during thermal transfer.

Examples of the inorganic particles include clay minerals such as talc and kaolin, carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, sulfates such as calcium sulfate, and oxides such as silica. , Graphite, saltpeter, and inorganic particles such as boron nitride.
As the organic particles, (meth) acrylic resin, Teflon (registered trademark) resin, silicone resin, lauroyl resin, phenol resin, acetal resin, styrene resin, polyamide resin, or the like, or these were reacted with a crosslinking material. Crosslinked resin particles and the like can be mentioned.

  The thickness of the back layer is preferably from 0.1 μm to 2 μm, and more preferably from 0.1 μm to 1 μm. This makes it possible to more effectively prevent sticking and wrinkles while maintaining the transfer of thermal energy during thermal transfer.

  The back layer is obtained by dispersing or dissolving the above material in water or a suitable solvent, and applying a known method such as a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, and a rod coating method. It can be formed by applying a film on a substrate to form a coating film and drying the coating film.

(Release layer)
In one embodiment, the thermal transfer sheet of the present invention includes a release layer between the substrate and the transfer layer. Thereby, transferability can be further improved.

  In one embodiment, the release layer contains a resin material, and includes, for example, (meth) acrylic resin, polyurethane, polyamide, polyester, melamine resin, polyol resin, cellulose resin, silicone resin, and the like.

  In one embodiment, the release layer includes a release material such as a silicone oil, a phosphate plasticizer, a fluorine compound, a wax, a metal soap, and a filler.

  The thickness of the release layer is not particularly limited, and can be, for example, 0.2 μm or more and 2 μm or less.

  The release layer is formed by dispersing or dissolving the above material in water or a suitable solvent, and applying a known means such as a roll coating method, a reverse roll coating method, a gravure coating method, a reverse gravure coating method, a bar coating method, and a rod coating method. Thus, it can be formed by applying a film on a base material to form a coating film and drying the coating film.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
A coating liquid for forming a release layer having the following composition was applied to one surface of a PET film having a thickness of 4.5 μm, and dried to form a release layer having a thickness of 1 μm.
<Coating liquid for forming release layer>
・ Styrene- (meth) acrylic copolymer 20 parts by mass (Dianal (registered trademark) BR-50, manufactured by Mitsubishi Chemical Corporation)
・ Methyl ethyl ketone (MEK) 40 parts by mass ・ Toluene 40 parts by mass

On the release layer formed as described above, a coating liquid for forming a plasticizer layer having the following composition was applied and dried to form a plasticizer layer having a thickness of 0.1 μm.
<Plasticizer layer forming coating liquid>
21.0 parts by mass of alumina sol (manufactured by Nissan Chemical Industries, Ltd., AS-200, solid content 10%)
-0.9 parts by mass of polyvinylpyrrolidone (PVP) (K-90, manufactured by ASP Japan Co., Ltd.)
・ 39.1 parts by mass of hydrochloric acid having a pH of 1 ・ 39.1 parts by mass of isopropanol (IPA)

On the plasticizer layer formed as described above, a coating solution for forming an adhesive layer having the following composition is applied and dried to form an adhesive layer having a thickness of 0.5 μm. And a transfer layer having an adhesive layer.
<Coating liquid for forming adhesive layer>
・ Polyester 20 parts by mass (Toyobo Co., Ltd., Byron (registered trademark) 200)
-10 parts by weight of a copolymer obtained by reaction bonding of an ultraviolet absorber (UVA-635L, manufactured by BASF Japan)
・ MEK 40 parts by mass ・ Toluene 40 parts by mass

A coating liquid for forming a primer layer having the following composition was applied onto a substrate and dried to form a primer layer having a thickness of 0.1 μm so that the transfer layer was formed in a plane-sequential manner.
<Coating liquid for forming primer layer>
21 parts by mass of alumina sol (Nissan Chemical Co., Ltd., alumina sol 200, solid content 10%)
・ PVP 0.9 parts by mass (K-90, manufactured by ASP Japan Co., Ltd.)
・ 39.1 parts by mass of hydrochloric acid of pH 1 ・ 39.1 parts by mass of IPA

  On the primer layer formed as described above, a coating liquid for forming a yellow dye layer, a coating liquid for forming a magenta dye layer, and a coating liquid for forming a cyan dye layer having the following composition are coated and dried in a sequential manner. Then, a yellow dye layer, a magenta dye layer and a cyan dye layer having a thickness of 0.5 μm were formed.

<Yellow dye layer forming coating liquid>
-Solvent Yellow 93 2 parts by mass-Disperse Yellow 231 2 parts by mass-Polyvinyl acetal 3.5 parts by mass (Eslek (registered trademark) KS-5, manufactured by Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 parts by mass ・ MEK 45 parts by mass ・ Toluene 45 parts by mass

<Coating solution for magenta dye layer formation>
-1.5 parts by mass of disperse dye (MS Red G)-2 parts by mass of disperse dye (Macrolex Red Violet R)-4.5 parts by mass of polyvinyl acetal (manufactured by Sekisui Chemical Co., Ltd., Eslek (registered trademark) KS- 5)
・ Polyethylene wax 0.1 parts by mass ・ MEK 45 parts by mass ・ Toluene 45 parts by mass

<Coating solution for forming cyan dye layer>
-2 parts by weight of Solvent Blue 63-2 parts by weight of Disperse Blue 354-3.5 parts by weight of polyvinyl acetal (Eslek (registered trademark) KS-5, manufactured by Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 parts by mass ・ MEK 45 parts by mass ・ Toluene 45 parts by mass

On the other surface of the PET film, a coating solution for forming a back layer having the following composition was applied and dried to form a back layer having a thickness of 0.5 μm, thereby obtaining a thermal transfer sheet.
<Coating liquid for back layer formation>
-51.2 parts by mass of polyvinyl acetal (manufactured by Sekisui Chemical Co., Ltd., Eslek (registered trademark) KS-1)
17.8 parts by mass of isocyanate compound (manufactured by DIC Corporation, Vernock (registered trademark) D750)
1 part by mass of silicone resin particles (Tospearl (registered trademark) 240, manufactured by Momentive Performance Materials Japan GK)
・ Zinc stearyl phosphate 10 parts by mass (LBT-1830 refined, manufactured by Sakai Chemical Industry Co., Ltd.)
・ 10 parts by mass of zinc stearate (SZ-PF, manufactured by Sakai Chemical Industry Co., Ltd.)
・ Polyethylene wax 10 parts by mass (Toyo Adress Co., Ltd., Polywax 3000)
・ MEK 200 parts by mass ・ Toluene 100 parts by mass

Example 2
A thermal transfer sheet was prepared in the same manner as in Example 1 except that the hydrochloric acid having a pH of 1 in the coating liquid for forming a plasticizer layer was changed to ion-exchanged water.

Example 3
A thermal transfer sheet was produced in the same manner as in Example 2, except that the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer were changed to the following compositions.
<Coating liquid for forming plasticizer layer and primer layer>
・ Silica sol 10.5 parts by mass (manufactured by Nissan Chemical Industries, Ltd., ST-OS, solid content 20%)
・ PVP 0.9 parts by mass (K-90, manufactured by ASP Japan Co., Ltd.)
・ 44.3 parts by mass of ion-exchanged water ・ 44.3 parts by mass of IPA

Example 4
A thermal transfer sheet was prepared in the same manner as in Example 1 except that the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer were changed to the following compositions.
<Coating liquid for forming plasticizer layer and primer layer>
21.0 parts by mass of alumina sol (manufactured by Nissan Chemical Industries, Ltd., AS-200, solid content 10%)
-3.6 parts by mass of polyurethane (manufactured by DIC Corporation, CP-7050, solid content 25%)
・ 37.7 parts by mass of hydrochloric acid of pH 1 ・ 37.7 parts by mass of IPA

Comparative Example 1
A thermal transfer sheet was produced in the same manner as in Example 1 except that the plasticizer layer and the primer layer were not provided.

Comparative Example 2
A thermal transfer sheet was produced in the same manner as in Example 1, except that the pH 1 water in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to an aqueous sodium hydroxide solution having a pH of 14.

Comparative Example 3
An attempt was made to produce a thermal transfer sheet in the same manner as in Example 1, except that the compositions of the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer were both changed as follows. The coating liquid for forming the plasticizer layer was repelled, and the plasticizer layer could not be formed.
<Coating liquid for forming plasticizer layer and primer layer>
・ Alumina sol 30.0 parts by weight ・ pH 1 hydrochloric acid 35.0 parts by weight ・ IPA 35.0 parts by weight

Comparative Example 4
An attempt was made to produce a thermal transfer sheet in the same manner as in Comparative Example 3 except that the hydrochloric acid of pH 1 in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to ion-exchanged water. The coating liquid for forming a plasticizer layer was repelled by the layer, and the plasticizer layer could not be formed.

Comparative Example 5
Production of a thermal transfer sheet was attempted in the same manner as in Comparative Example 3, except that the hydrochloric acid of pH 1 in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to an aqueous solution of sodium hydroxide having a pH of 14. However, the coating liquid for forming a plasticizer layer was repelled by the release layer, and the plasticizer layer could not be formed.

Comparative Example 6
A thermal transfer sheet was produced in the same manner as in Example 3, except that the ion exchange water in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to hydrochloric acid having a pH of 1.

Comparative Example 7
A thermal transfer sheet was prepared in the same manner as in Example 3, except that the ion-exchanged water in the coating liquid for forming a plasticizer-resistant layer and the coating liquid for forming a primer layer was changed to an aqueous solution of sodium hydroxide having a pH of 14.

Comparative Example 8
A thermal transfer sheet was produced in the same manner as in Example 1, except that the compositions of the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer were both changed as follows.
<Coating liquid for forming plasticizer layer and primer layer>
・ PVP 3 parts by weight ・ pH1 hydrochloric acid 48.5 parts by weight ・ IPA 48.5 parts by weight

Comparative Example 9
A heat transfer sheet was produced in the same manner as in Comparative Example 8, except that the hydrochloric acid of pH 1 in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to ion-exchanged water.

Comparative Example 10
A thermal transfer sheet was produced in the same manner as in Comparative Example 8 except that the hydrochloric acid of pH 1 in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to an aqueous solution of sodium hydroxide having a pH of 14.

Comparative Example 11
A thermal transfer sheet was produced in the same manner as in Example 1, except that the composition of the coating liquid for forming a release layer was changed as follows.
<Coating liquid for forming release layer>
20 parts by mass of (meth) acrylic resin (Dianal (registered trademark) BR-83, manufactured by Mitsubishi Chemical Corporation)
・ MEK 40 parts by mass ・ Toluene 40 parts by mass

Comparative Example 12
A thermal transfer sheet was produced in the same manner as in Comparative Example 11 except that the plasticizer layer and the primer layer were not provided.

Comparative Example 13
A thermal transfer sheet was prepared in the same manner as in Example 4, except that the hydrochloric acid of pH 1 in the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer was changed to an aqueous solution of sodium hydroxide having a pH of 14.

Comparative Example 14
A thermal transfer sheet was produced in the same manner as in Example 1, except that the compositions of the coating liquid for forming a plasticizer layer and the coating liquid for forming a primer layer were both changed as follows.
<Coating liquid for forming plasticizer layer and primer layer>
・ Polyurethane 12.0 parts by mass (manufactured by DIC Corporation, CP-7050, solid content 25%)
・ 44.0 parts by mass of hydrochloric acid of pH 1 ・ 44.0 parts by mass of IPA

<<< Development area ratio (Sdr) measurement of interface of plasticizer resistant layer >>>
The adhesive layer provided in the thermal transfer sheets obtained in the above Examples and Comparative Examples was wiped with a mixed liquid of MEK: toluene = 1: 1 to expose the plasticizer-resistant layer.
Next, the development area ratio (Sdr) of the plasticizer-resistant layer was measured using a laser microscope (manufactured by Keyence Corporation, measuring unit VK-X160, controller VK-X150, objective lens magnification: 10 times, measurement mode: surface shape, measurement size) : Standard (1024 x 768), number of pixels (1024, 768)) and measured by an analysis application. Table 1 summarizes the measurement results.
In Comparative Examples 3 to 5, "-" was indicated in the table because a plasticizer-resistant layer could not be formed.

<< Plasticizer resistance evaluation >>
Using a sublimation type thermal transfer printer (DS620, manufactured by Dai Nippon Printing Co., Ltd.) and the thermal transfer sheets obtained in the above Examples and Comparative Examples, on a receiving layer provided on a thermal transfer image receiving sheet manufactured by Dai Nippon Printing Co., Ltd. A black solid image (0/255 image gradation) was printed, and then the transfer layer was transferred to produce a print.
The printed matter produced as described above was cut into a length of 5 cm × width 5 cm, and a transfer layer surface and a plasticizer-containing soft vinyl chloride sheet (Altron (registered trademark) # 480, manufactured by Mitsubishi Chemical Corporation, length 5 cm × width) (5 cm × 400 μm in thickness), and they were left standing for 48 hours in an environment of 50 ° C. and 15% relative humidity under a load of 1 kg.
The printed matter after standing was visually checked and evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
In Comparative Examples 1 and 12, the dye was abnormally transferred, and a solid black image could not be printed.
Further, in Comparative Examples 3 to 5, "-" was indicated in the table because the plasticizer layer could not be formed.
(Evaluation criteria)
A: No bleeding was observed in the image formed on the print.
B: Slight bleeding was observed in the image formed on the print, but it was practically no problem.
NG: Bleeding was confirmed in the image formed on the print, which was practically a problem.

<< Glossiness evaluation >>
The glossiness of the print surface obtained in the plasticizer resistance test was measured using a photometer (Gloss Meter VG7000, manufactured by Nippon Denshoku Industries Co., Ltd.) based on JIS-Z-8741 (1997). It was measured at a reflection angle of 20 ° and evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
In Comparative Examples 1 and 12, the dye was abnormally transferred, and a solid black image could not be printed.
In Comparative Examples 3 to 5, "-" was indicated in the table because a plasticizer-resistant layer could not be formed.
(Evaluation criteria)
A: It was 60 or more.
B: 50 or more and less than 60.
NG: less than 50.

<< Image density measurement >>
The density of the image formed on the print obtained in the plasticizer resistance test was measured with an optical densitometer (RD918, manufactured by X-Rite). Table 1 summarizes the measurement results.
In Comparative Examples 1 and 12, the dye was abnormally transferred, and a solid black image could not be printed.

<< Dye layer retention evaluation >>
Cellotape (registered trademark) was affixed to the dye layer of the thermal transfer sheet obtained in each of the above Examples and Comparative Examples by rubbing and reciprocating with a thumb twice, and then immediately peeled off at 90 °. The cellophane tape after peeling was visually observed and evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
A: No adhesion of the dye layer occurred in the peeled tape.
NG: The dye layer adhered to the peeled tape.

10: thermal transfer sheet, 11: substrate, 12: transfer layer, 13: release layer, 14: plasticizer layer, 15: adhesive layer, 16: primer layer, 17: dye layer, 18: back layer

Claims (7)

Comprising a base material and a transfer layer,
The transfer layer includes a release layer containing a styrene- (meth) acrylic copolymer, and a plasticizer layer containing a metal oxide and a resin material,
A thermal transfer sheet, wherein a development area ratio (Sdr) of an interface on a surface of the plasticizer layer opposite to a surface on which the release layer is provided is 0.5 or less.   2. The thermal transfer sheet according to claim 1, wherein the plasticizer layer includes at least one of aluminum oxide and silicon oxide as the metal oxide. 3.   The thermal transfer sheet according to claim 1, wherein the content of the metal oxide in the plasticizer-resistant layer is 20% by mass or more and 90% by mass or less.   The thermal transfer sheet according to any one of claims 1 to 3, wherein the resin material is a vinyl resin.   The thermal transfer sheet according to any one of claims 1 to 4, wherein the content of the resin material in the plasticizer-resistant layer is 10% by mass or more and 80% by mass or less.   The thermal transfer sheet according to claim 1, wherein the transfer layer further includes an adhesive layer on the plasticizer layer. A primer layer and a dye layer formed on the primer layer so as to be surface-sequential with the transfer layer,
The thermal transfer sheet according to any one of claims 1 to 6, wherein the primer layer and the plasticizer-resistant layer are formed of the same material.

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