JP7421750B2 - A thermal transfer sheet and a combination of the thermal transfer sheet and an intermediate transfer medium - Google Patents

Description

The present disclosure relates to thermal transfer sheets and combinations of the thermal transfer sheets and intermediate transfer media.

Conventionally, various thermal transfer recording methods are known. For example, a thermal transfer sheet having a transfer layer having a melt-transferable color material layer on a base material is superimposed on an object to be transferred, and then passed between a thermal head and a platen roller of a thermal transfer printer, and 2. Description of the Related Art A thermal melt transfer method is known in which a thermal transfer sheet is heated by a head to transfer a transfer layer onto a transfer target to form an image and produce a printed matter.

Furthermore, it is widely practiced to produce printed matter by using such a thermal transfer sheet in combination with an intermediate transfer medium.
Specifically, first, a thermal transfer sheet and an intermediate transfer medium are overlapped, and the thermal transfer sheet is heated to form an image on a receptor layer provided on the intermediate transfer medium (primary transfer). Next, by overlapping the intermediate transfer medium and the object to be transferred, and by heating the intermediate transfer medium, the receiving layer on which the image is formed is transferred onto the object to be transferred (secondary transfer), and a printed matter is manufactured. do.

In the production of prints using the above-mentioned thermal transfer sheet and intermediate transfer medium, the transfer layer of the thermal transfer sheet is It is desired that the image be transferred onto the receiving layer. When the thermal transfer sheet and the intermediate transfer medium are peeled off at a low temperature of about 60° C. during primary transfer, this becomes a particular problem because there is an increased possibility that reverse transfer will occur.

The object of the present disclosure is to effectively suppress the occurrence of reverse transfer even when peeling between a thermal transfer sheet and an intermediate transfer medium during primary transfer is performed at low temperatures (hereinafter referred to as reverse transfer inhibiting property). It is to provide sheets.
It is also an object of the present disclosure to provide a combination of the thermal transfer sheet and an intermediate transfer medium.

The thermal transfer sheet of the present disclosure includes a first base material, a release layer, and a transfer layer including at least a melt transfer coloring material layer,
The release layer includes at least two types of urethane resin and at least one type of acetal resin,
The thermal peeling force of the transfer layer with a width of 25 mm is 0.4 N or more and 0.8 N or less.

A combination of a thermal transfer sheet and an intermediate transfer medium according to the present disclosure includes an intermediate transfer medium including the thermal transfer sheet, a second base material, and a receptor layer.

According to the present disclosure, it is possible to provide a thermal transfer sheet that has high reverse transfer inhibiting properties. Further, according to the present disclosure, a combination of the thermal transfer sheet and an intermediate transfer medium can be provided.

1 is a schematic cross-sectional view showing an embodiment of a thermal transfer sheet of the present disclosure. 1 is a schematic cross-sectional view showing an embodiment of a thermal transfer sheet of the present disclosure. 1 is a schematic cross-sectional view showing an embodiment of a thermal transfer sheet of the present disclosure. 1 is a schematic cross-sectional view showing an embodiment of a combination of a thermal transfer sheet of the present disclosure and an intermediate transfer medium. FIG. 2 is a front view showing a pattern image A formed on a receptor layer included in an intermediate transfer medium in an example. 6 is a partially enlarged view of pattern image A in FIG. 5. FIG.

(thermal transfer sheet)
The thermal transfer sheet 10 according to the present disclosure includes a first base material 11, a release layer 12, and a transfer layer 13, as shown in FIG. The transfer layer 13 includes at least a melt transfer type coloring material layer 14 .
In one embodiment, as shown in FIG. 2, the transfer layer 13 includes a release layer 15 below the melt transfer colorant layer 14.
In one embodiment, the thermal transfer sheet 10 includes a sublimation transfer type coloring material layer 16 in a plane-sequential manner with the transfer layer 12, as shown in FIG. Further, in one embodiment, the thermal transfer sheet 10 includes a primer layer between the first base material and the sublimation transfer color material layer 16 (not shown).
In one embodiment, the thermal transfer sheet 10 includes a back layer 17 on the surface of the first base material 11 opposite to the surface on which the transfer layer 13 is provided.
Each layer included in the thermal transfer sheet of the present disclosure will be described below.

(Base material)
The base material can be used without any particular limitations as long as it has heat resistance to the thermal energy applied during thermal transfer and has mechanical strength and solvent resistance that can support the transfer layer etc. provided on the base material.

As the base material, a film made of a resin material (hereinafter simply referred to as "resin film") can be used. For example, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), 1,4-polycyclohexylene dimethylene terephthalate, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, nylon polyamides such as 6 and nylon 6,6, polyolefins such as polyethylene (PE), polypropylene (PP) and polymethylpentene, polyvinyl chloride, polyvinyl alcohol (PVA), polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, and Vinyl resins such as polyvinylpyrrolidone (PVP), vinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, (meth)acrylic resins such as polyacrylate and polymethacrylate, imide resins such as polyimide and polyetherimide, cellophane, cellulose acetate, Examples include cellulose resins such as nitrocellulose, cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB), styrene resins such as polystyrene (PS), polycarbonate, and ionomer resins.
Among the above resin materials, from the viewpoint of heat resistance and mechanical strength, polyester is preferable, PET or PEN is more preferable, and PET is particularly preferable.

Furthermore, a laminate of the resin films described above can also be used as a base material. The resin film laminate can be produced by using a dry lamination method, a wet lamination method, an extrusion method, or the like.

When the base material 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 direction or biaxial direction is preferred. It is preferable to use

The thickness of the base material is preferably 3.0 μm or more and 25.0 μm or less. This makes it possible to improve the mechanical strength of the base material and the transmission of thermal energy during thermal transfer.

(Release layer)
The release layer contains at least two types of urethane resins and at least one type of acetal resin.
In the present disclosure, a resin having a urethane bond is meant, and for example, a urethane resin can be obtained by reacting a polyol compound and an isocyanate compound.
Examples of the polyol include polyethylene glycol, polypropylene glycol, acrylic polyol, polyester polyol, polyether polyol, polycarbonate polyol, and polyurethane polyol. Examples of the isocyanate compound include 2,4-tolylene diisocyanate, xylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. etc.
In the present disclosure, the acetal resin means a resin obtained by acetalizing an alcohol such as polyvinyl alcohol with an aldehyde.
Examples of the aldehyde include propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, and formaldehyde. , acetaldehyde, benzaldehyde, and the like.

The release layer includes a high Tg urethane resin and a low Tg urethane resin. Thereby, the reverse transcription inhibition property can be further improved. In addition, it is possible to effectively suppress blurring and fading in images formed by primary transfer of the transfer layer (hereinafter referred to as transferability).
The glass transition temperature (Tg) of the high Tg urethane resin is 50°C or higher, and the glass transition temperature (Tg) of the low Tg urethane resin is 10°C or lower.
It is preferable that the glass transition temperature (Tg) of the high Tg urethane resin is 50°C or more and 110°C or less, and the glass transition temperature (Tg) of the low Tg urethane resin is Tg-50°C or more and 10°C or less.
The Tg of the high Tg urethane resin is more preferably 70°C or more and 100°C or less.
The Tg of the low Tg urethane resin is more preferably -40°C or more and 0°C or less.
Note that in the present disclosure, Tg is a value determined by DSC (differential scanning calorimetry) in accordance with JIS K 7121.

When the release layer contains a high Tg urethane resin and a low Tg urethane resin, the content ratio of these (high Tg urethane resin/low Tg urethane resin) is preferably 5/30 or more and 30/5 or less on a mass basis. , more preferably 5/25 or more and 15/20 or less. Thereby, reverse transcription inhibition and transferability can be further improved.

The content of the urethane resin in the release layer is preferably 10% by mass or more and 45% by mass or less, and more preferably 15% by mass or more and 40% by mass or less. Thereby, reverse transcription inhibition and transferability can be further improved.
When the mold release layer contains the Tg of a high Tg urethane resin and a low Tg urethane resin, the content of the high Tg urethane resin in the mold release layer is preferably 5% by mass or more and 35% by mass or less, and 10% by mass or more and 30% by mass. % or less is more preferable. Thereby, reverse transcription inhibition and transferability can be further improved.
Further, the content of the low Tg urethane resin in the release layer is preferably 3% by mass or more and 35% by mass or less, and more preferably 5% by mass or more and 25% by mass or less. Thereby, reverse transcription inhibition and transferability can be further improved.

The Tg of the acetal resin is preferably 60°C or more and 120°C or less, more preferably 80°C or more and 120°C or less. Thereby, transferability can be further improved.

The content of the acetal resin in the release layer is preferably 55% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 85% by mass or less. Thereby, transferability can be further improved.

In one embodiment, the release layer includes at least one release agent. Examples include fluorine compounds, phosphoric acid ester compounds, silicone oils, higher fatty acid amide compounds, metal soaps, and waxes such as paraffin wax.
Examples of the silicone oil include straight silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, as well as amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, (meth)acrylic-modified silicone oil, mercapto-modified silicone oil, Examples include modified silicone oils such as carbinol-modified silicone oil, fluorine-modified silicone oil, methylstyryl-modified silicone oil, and polyether-modified silicone oil. Note that the modified silicone oil includes single-terminal type, double-terminal type, and side chain single-terminal type.

The release layer may contain resin materials other than urethane resin and acetal resin. Examples include polyester, polyamide, polyolefin, vinyl resin, cellulose resin, styrene resin, polycarbonate, and ionomer resin.

The release layer may contain additives. Examples include fillers, plasticizers, antistatic materials, ultraviolet absorbers, organic particles, inorganic particles, mold release agents, and dispersants. .

The thickness of the release layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 2 μm or less. Thereby, reverse transcription inhibition and transferability can be further improved.

The release layer is prepared by dispersing the above material in water or an appropriate solvent, or by dissolving the material in water or an appropriate solvent to prepare a coating solution, and applying it onto the first base material to form a coating film. It can be formed by forming and drying this. As a coating method, 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, or a rod coating method can be used.

(transfer layer)
The transfer layer includes at least a melt transfer type coloring material layer. Further, in one embodiment, the transfer layer includes a release layer below the melt-transferable colorant layer.

In the thermal transfer sheet of the present disclosure, the thermal peeling force of the 25 mm wide transfer layer is 0.4N or more and 0.8N or less. Thereby, reverse transcription inhibition can be effectively improved.
The thermal peeling force of the transfer layer is more preferably 0.4 N or more and 0.6 N or less.
In the present disclosure, the thermal peeling force of the transfer layer is measured as follows.
First, prepare a thermal transfer sheet and a polyvinyl chloride (PVC) card (manufactured by Dainippon Printing Co., Ltd., width 50 mm x length 70 mm), and place the transfer layer of the thermal transfer sheet and the PVC card facing each other, and then Printing is performed using a test printer to obtain a laminate in which the thermal transfer sheet and PVC are in close contact with each other.
Next, the laminate is cut to a width of 25 mm to obtain a peel force measurement sample having a width of 25 mm and a length of 70 mm.
A peel tester (manufactured by Kyowa Kaimen Kagaku Co., Ltd., VPA-3) is prepared, and the above peel force measurement sample is placed on the stage of the peel tester so that the transferred object side is in contact with the stage.
Set the peel tester as follows and let it stand for 3 minutes.
Next, the base material of the thermal transfer sheet is peeled off, and the peel force between the base material and the transfer layer is measured.
(test printer)
・Thermal head: Kyocera Corporation, KEE-57-12GAN2-STA
・Heating element average resistance value: 3303Ω
・Main scanning direction resolution: 300 dpi (dots per inch)
・Sub-scanning direction resolution: 300dpi
・Printing voltage: 18V
・Line speed: 2.0msec. /line
・Printing start temperature: 35℃
・Pulse duty ratio: 85%
・Print image: Solid black image (0/255 gradation)

(Peel tester conditions)
・Stage temperature: 60℃
・Peeling angle: 90°
・Peeling speed: 2000mm/min

(melt transfer type color material layer)
The melt transfer type coloring material layer contains at least one kind of coloring material, which may be a pigment or a dye. For example, carbon black, acetylene black, lamp black, black smoke, iron black, aniline black, silica, calcium carbonate, titanium oxide, cadmium red, cadmopon red, chrome red, vermilion, red iron, azo pigments, alizarin lake, quinacridone, Cochineal lake perylene, yellow ocher, aureolin, cadmium yellow, cadmium orange, chrome yellow, zinc yellow, Naples yellow, nickel yellow, azo pigments, greenish yellow, ultramarine, ultramarine, cobalt, phthalocyanine, anthraquinone, indicoid, Examples include cinnabar green, cadmium green, chrome green, phthalocyanine, azomethine, perylene, and aluminum pigments.

The content of the coloring material in the melt transfer type coloring material layer is preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 45% by mass or less. Thereby, the density of the formed image can be improved.

In one embodiment, the melt transfer colorant layer includes at least one resin material. Examples include polyester, polyamide, polyolefin, vinyl resin, vinyl acetal resin, (meth)acrylic resin, cellulose resin, styrene resin, polycarbonate, butyral resin, phenoxy resin, and ionomer resin.
Among these, vinyl resins are preferred, and vinyl chloride-vinyl acetate copolymers are particularly preferred, from the viewpoint of adhesion to a receptor layer included in an intermediate transfer medium to be described later.

The content of the resin material in the melt transfer color material layer is preferably 20% by mass or more and 75% by mass or less, and more preferably 30% by mass or more and 60% by mass or less. Thereby, it is possible to further improve the adhesion with the receiving layer provided in the intermediate transfer medium, which will be described later.

The melt transfer type coloring material layer may contain the above-mentioned additives.

The thickness of the melt transfer color material layer is, for example, 0.3 μm or more and 5 μm or less.

The melt-transfer type color material layer is prepared by dispersing the above materials in water or an appropriate solvent, or by dissolving the above materials in water or an appropriate solvent to prepare a coating solution, and applying the release layer using the above coating method. It can be formed by coating it on a surface such as the like to form a coating film, and drying this.

(Peeling layer)
In one embodiment, the transfer layer included in the thermal transfer sheet includes a release layer below the melt-transferable colorant layer.

The release layer includes at least one resin material. Examples include polyester, polyamide, polyolefin, vinyl resin, (meth)acrylic resin, imide resin, cellulose resin, styrene resin, polycarbonate, and ionomer resin.
Among these, (meth)acrylic resin or vinyl resin is preferable, and it is more preferable to contain both of these resins. Thereby, reverse transcription inhibition and transferability can be further improved.
Among vinyl resins, vinyl chloride-vinyl acetate copolymer is more preferred.

The content of the resin material in the release layer is preferably 80% by mass or more and 99.9% by mass or less, more preferably 90% by mass or more and 99.5% by mass or less. Thereby, reverse transcription inhibition and transferability can be further improved.

In one embodiment, the release layer includes the above mold release agent. Thereby, reverse transcription inhibition and transferability can be further improved. Among the above, silicone oil is preferred.

The content of the release agent in the release layer is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less. Thereby, reverse transcription inhibition and transferability can be further improved.

The release layer may contain the above additives.

The thickness of the release layer is preferably 0.1 μm or more and 3 μm or less, more preferably 0.3 μm or more and 1.5 μm or less. As a result, reverse transcription inhibition and transferability can be further improved.

The release layer is prepared by dispersing the above material in water or an appropriate solvent, or by dissolving the above material in water or an appropriate solvent to create a coating solution, and applying it onto the release layer using the above coating means. It can be formed by forming a coating film and drying it.

(sublimation transfer type color material layer)
In one embodiment, the thermal transfer sheet of the present disclosure includes a sublimation transfer type coloring material layer on a first base material so as to be surface sequential with the transfer layer. A plurality of sublimation transfer color material layers may be provided.

The sublimation transfer color material layer contains at least one sublimable dye. For example, diarylmethane dyes, triarylmethane dyes, thiazole dyes, merocyanine dyes, pyrazolone dyes, methine dyes, indoaniline dyes, acetophenone azomethine dyes, pyrazoloazomethine dyes, xanthene dyes, oxazine dyes, thiazine dyes, azine dyes, acridine dyes , azo dyes, spiropyran dyes, indolinospiropyran dyes, fluoran dyes, naphthoquinone dyes, anthraquinone dyes, and quinophthalone dyes.

In one embodiment, the sublimation transfer colorant layer includes at least one resin material. Examples include (meth)acrylic resin, polyurethane, acetal resin, polyamide, polyester, melamine resin, polyol resin, cellulose resin, and silicone resin.

In one embodiment, the sublimation transfer type coloring material layer contains the above mold release agent. Thereby, during image formation, it is possible to prevent the receiving layer provided in the intermediate transfer medium described later from fusing with the sublimation transfer type coloring material layer.

The content of the release agent in the sublimation transfer color material layer is preferably 0.01% by mass or more and 1% by mass or less, more preferably 0.05% by mass or more and 0.5% by mass or less. Thereby, during image formation, it is possible to further prevent fusion between the receptor layer and the sublimation transfer type color material layer provided in the intermediate transfer medium, which will be described later.

The sublimation transfer type coloring material layer may contain the above-mentioned additive.

The sublimation transfer type color material layer is prepared by dispersing the above materials in water or an appropriate solvent, or by dissolving the above materials in water or an appropriate solvent to prepare a coating solution, and applying the first base layer using the above coating means. It can be formed by applying it on a material, etc. to form a coating film, and drying this.

(Primer layer)
In one embodiment, the thermal transfer sheet includes a primer layer between the first substrate and the sublimation transfer coloring material layer.

In one embodiment, the primer layer includes at least one resin material. Examples include polyester, vinyl resin, polyurethane, (meth)acrylic resin, polyamide, polyether, styrene resin, and cellulose resin.
Further, the primer layer may contain the above-mentioned additives.

The thickness of the primer layer is, for example, 0.05 μm or more and 2.0 μm or less.

The primer layer is prepared by dispersing the above material in water or an appropriate solvent, or dissolving the above material in water or an appropriate solvent to prepare a coating liquid, and applying it onto the base material using the above coating means. It can be formed by forming a coating film and drying it.

(back layer)
In one embodiment, the thermal transfer sheet includes a back layer on the side of the first substrate opposite to the side on which the transfer layer is provided. This can prevent sticking and wrinkles from occurring due to heating during thermal transfer.

In one embodiment, the back layer includes at least one resin material. Examples include vinyl resin, polyester, polyamide, polyolefin, (meth)acrylic resin, polyolefin, polyurethane, cellulose resin, and phenol resin.

In one embodiment, the back layer includes at least one isocyanate compound. Examples include xylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

The back layer may contain the above mold release agent and additives.

The thickness of the back layer is, for example, 0.3 μm or more and 3.0 μm or less.

The back layer is formed by dispersing the above-mentioned material in water or an appropriate solvent, or dissolving the above-mentioned material in water or an appropriate solvent to prepare a coating liquid, and coating it on the first base material by the above-mentioned coating means. It can be formed by forming a coating film and drying it.

(Combination of thermal transfer sheet and intermediate transfer medium)
A combination of a thermal transfer sheet and an intermediate transfer medium according to the present disclosure, as shown in FIG.
A thermal transfer sheet 10 comprising at least the first base material 11 described above, a release layer 12, and a transfer layer 13;
An intermediate transfer medium 20 including a second base material 21 and a receptor layer 22 is provided.
In one embodiment, intermediate transfer medium 20 includes a release layer between second substrate 21 and receptive layer 22 (not shown).
In one embodiment, intermediate transfer medium 20 includes a release layer between second substrate 21 and receptive layer 22 (not shown). When the intermediate transfer medium 20 includes a release layer and a release layer, the release layer and the release layer are provided in this order between the second base material 21 and the receiving layer 22.
In one embodiment, intermediate transfer medium 20 includes a protective layer between second substrate 21 and receptive layer 22 (not shown). When the intermediate transfer medium 20 includes a release layer and a protective layer, the release layer and the protective layer are provided in this order between the second base material 21 and the receptor layer 22.
Each layer included in the intermediate transfer medium constituting the combination of the present disclosure will be described below. Since the thermal transfer sheet has been described above, the description thereof will be omitted here. Further, the release layer and release layer that the intermediate transfer medium may include are also the same as the release layer and release layer that the thermal transfer sheet includes, so description thereof will be omitted here.

(intermediate transfer medium)
(Second base material)
As the second base material, materials that can be used for the first base material can be appropriately selected and used.

The thickness of the second base material is, for example, 1 μm or more and 50 μm or less.

(receptive layer)
In one embodiment, the receptive layer includes at least one resin material. For example, polyolefins, vinyl resins such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymers, (meth)acrylic resins, cellulose resins, polyesters, polyamides, polycarbonates, styrene resins, epoxy resins, polyurethanes, epoxy resins, ionomer resins, etc. can be mentioned.
Among these, vinyl resins are preferred, and vinyl chloride-vinyl acetate copolymers are particularly preferred, from the viewpoint of adhesion to the melt-transfer colored layer and receptivity to sublimable dyes.

The content of the resin material in the receptor layer is preferably 80% by mass or more and 99.5% by mass or less, more preferably 85% by mass or more and 99% by mass or less. Thereby, it is possible to further improve the adhesion with the melt-transfer colored layer and the receptivity to the sublimable dye.

The receptor layer may contain the above mold release agent and additives.

The thickness of the receptor layer is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less.

The receptor layer is formed by dispersing the above-mentioned material in water or an appropriate solvent, or dissolving the above-mentioned material in water or an appropriate solvent to prepare a coating liquid, and coating it on the second base material by the above-mentioned coating means. It can be formed by forming a coating film and drying it.

(protective layer)
The protective layer includes at least one resin material. Examples include polyester, (meth)acrylic resin, epoxy resin, styrene resin, acrylic polyol resin, polyurethane, and actinic light-curable resin.
In addition, in the present disclosure, "actinic light-curable resin" means a resin that has been cured by irradiating actinic light-curable resin with actinic light.
In addition, in the present disclosure, "actinic rays" refers to radiation that chemically acts on actinic ray-curable resins to promote polymerization, and specifically includes visible rays, ultraviolet rays, X-rays, and electron rays. rays, α rays, β rays, γ rays, etc.

The protective layer may contain the above additives.

The thickness of the protective layer is preferably 0.5 μm or more and 7 μm or less, more preferably 1 μm or more and 5 μm or less. Thereby, the durability of the protective layer can be further improved.

The protective layer is prepared by dispersing the above material in water or an appropriate solvent, or by dissolving the above material in water or an appropriate solvent to prepare a coating liquid, and applying it on the second base material etc. using the above coating means. It can be formed by applying it to a surface to form a coating film and drying it.

Next, the thermal transfer sheet of the present disclosure will be described in more detail with reference to Examples, but the thermal transfer sheet of the present disclosure is not limited to these Examples.

Example 1
[Preparation of thermal transfer sheet]
A mold release layer forming coating solution having the following composition was applied to one side of a 4.5 μm thick PET film and dried to form a 0.8 μm thick mold release layer.
<Coating liquid for mold release layer formation>
・High Tg urethane resin A 7 parts by mass (Tg92°C)
・Low Tg urethane resin B 23 parts by mass (Tg-30°C)
・70 parts by mass of acetal resin (manufactured by Sekisui Chemical Co., Ltd., S-LEC (registered trademark) KS-5, Tg 110°C)
・Toluene 950 parts by mass ・Methyl ethyl ketone (MEK) 950 parts by mass

A coating solution for forming a release layer having the following composition was applied onto the release layer and dried to form a release layer with a thickness of 1 μm.
<Coating liquid for forming release layer>
- Vinyl chloride-vinyl acetate copolymer 85 parts by mass (Solvine (registered trademark) CNL, manufactured by Nissin Chemical Industry Co., Ltd.)
・(Meth)acrylic resin 15 parts by mass (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., Vanaresin GH-8701)
・2 parts by mass of epoxy modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KP-1800U)
・Toluene 150 parts by mass ・MEK 150 parts by mass

A coating solution for forming a melt transfer color material layer having the following composition was applied onto the release layer and dried to form a melt transfer color material layer having a thickness of 1.5 μm. In this example, the release layer and the melt-transfer type color material layer correspond to the transfer layer.
<Coating liquid for forming melt transfer type color material layer>
・Carbon black 40 parts by mass ・Vinyl chloride-vinyl acetate copolymer 60 parts by mass ・Toluene 100 parts by mass

On the other side of the PET film, a coating liquid for forming a back layer having the following composition was applied and dried to form a back layer having a thickness of 1 μm, thereby obtaining a thermal transfer sheet.
<Coating liquid for forming back layer>
・Polyvinyl butyral 20 parts by mass (Sekisui Chemical Co., Ltd., S-LEC (registered trademark) BX-1)
・Isocyanate compound 44 parts by mass (DIC Corporation, Burnock (registered trademark) D750)
・Surfactant 13 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd., Plysurf (registered trademark) A208N)
・3 parts by mass of talc (manufactured by Nippon Talc Co., Ltd., Micro Ace (registered trademark) P-3, average particle size 5 μm)
・Toluene 460 parts by mass ・MEK 460 parts by mass

[Preparation of intermediate transfer medium]
A PET film with a thickness of 12 μm was prepared as the second base material. A coating solution for forming a release layer having the following composition was applied to one side of this PET film and dried to form a release layer with a thickness of 1 μm.
<Coating liquid for forming release layer>
・(Meth)acrylic resin 95 parts by mass (Dyanal (registered trademark) BR-87, manufactured by Mitsubishi Chemical Corporation)
・Polyester 5 parts by mass (manufactured by Toyobo Co., Ltd., Byron (registered trademark) 200)
・Toluene 200 parts by mass ・MEK 200 parts by mass

A coating solution for forming a protective layer having the following composition was applied onto the release layer and dried to form a protective layer with a thickness of 1.5 μm.
<Coating liquid for forming protective layer>
・Polyester 20 parts by mass (manufactured by Unitika Co., Ltd., ELITEL (registered trademark) UE-9885)
・Toluene 40 parts by mass ・MEK 40 parts by mass

On the protective layer, a coating liquid for forming a receptor layer having the following composition was applied and dried to form a receptor layer with a thickness of 1.5 μm, thereby obtaining an intermediate transfer medium.
<Coating liquid for forming receptor layer>
- Vinyl chloride-vinyl acetate copolymer 95 parts by mass (Solvine (registered trademark) CNL, manufactured by Nissin Chemical Industry Co., Ltd.)
・Epoxy modified silicone oil 5 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., KP-1800U)
・Toluene 200 parts by mass ・MEK 200 parts by mass

Examples 2 to 7 and Comparative Examples 1 to 4
A thermal transfer sheet was produced in the same manner as in Example 1, except that the composition of the release layer was changed as shown in Table 1.

<<Heat peel force measurement>>
The melt transfer type coloring material layer surface of the thermal transfer sheets obtained in Examples and Comparative Examples and a polyvinyl chloride (PVC) card (manufactured by Dainippon Printing Co., Ltd., width 50 mm x length 70 mm) as a transfer target were They were placed facing each other and printed using the test printer described below to obtain a laminate in which the thermal transfer sheet and the object to be transferred were in close contact with each other.
(test printer)
・Thermal head: Kyocera Corporation, KEE-57-12GAN2-STA
・Heating element average resistance value: 3303Ω
・Main scanning direction resolution: 300 dpi (dots per inch)
・Sub-scanning direction resolution: 300dpi
・Printing voltage: 18V
・Line speed: 2.0msec. /line
・Printing start temperature: 35℃
・Pulse duty ratio: 85%
・Print image: Solid black image (0/255 image tone)

The above laminate was cut to a width of 25 mm to obtain a peel force measurement sample of 25 mm width x 70 mm length. A peel tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3) was prepared, and the above peel force measurement sample was placed on the stage of the peel tester so that the transferred object side was in contact with the stage. The peel tester was set as follows and left to stand for 3 minutes.
Next, the base material of the thermal transfer sheet was peeled off, and the peeling force was measured. The peeling interface was between the release layer and the release layer.
(Peel tester conditions)
・Stage temperature: 60℃
・Peeling angle: 90°
・Peeling speed: 2000mm/min

<<Evaluation of reverse transcription inhibition>>
Thermal transfer sheets obtained in Examples and Comparative Examples, an intermediate transfer medium prepared as described below, and a printer (manufactured by Canon Finetech Nisca Co., Ltd., PR-C201) were prepared.
Using the printer described above, the transfer layer of the thermal transfer sheet was transferred onto the receiving layer of the intermediate transfer medium to form a pattern image A (line thickness: 2 dots) shown in FIG. Note that the image formation was performed in an environment of 10° C. and 30% relative humidity. Further, FIG. 6 shows an enlarged view of a part of the pattern image.
The image-formed intermediate transfer medium was visually observed and evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
A: No peeling of the receptor layer was observed, and high reverse transfer inhibition was confirmed.
NG: Peeling of the receiving layer was observed.

<<Transferability evaluation-1>>
Thermal transfer sheets, intermediate transfer media, the above PVC cards, and the above printers obtained in Examples and Comparative Examples were prepared.
Using the printer described above, the transfer layer of the thermal transfer sheet was transferred onto the receiving layer of the intermediate transfer medium to form pattern image A. Note that the image formation was performed in an environment of 20° C. and 50% relative humidity.
After image formation, the receiving layer and release layer of the intermediate transfer medium were transferred onto a PVC card to produce a print.
The obtained prints were visually observed and evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
A: No blurring was observed in the formed image.
B: Slight blurring was observed in the formed image, but it was of a level that caused no practical problems.
NG: Occurrence of blurring was observed in the formed image, causing a practical problem.

<<Transferability evaluation-2>>
The prints obtained in the above transferability evaluation-1 were visually observed and evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
A: No fading was observed in the formed image.
B: Although slight fading was observed in the formed image, it was of a level that caused no practical problems.
NG: Occurrence of fading was observed in the formed image, causing a practical problem.

Hereinafter, one embodiment of the thermal transfer sheet of the present disclosure and a combination of the thermal transfer sheet and an intermediate transfer medium will be illustrated. Note that the thermal transfer sheet and the combination of the thermal transfer sheet and the intermediate transfer medium of the present disclosure are not limited to these.

The thermal transfer sheet of the present disclosure includes a first base material, a release layer, and a transfer layer including at least a melt transfer coloring material layer,
The 25 mm wide release layer includes at least two urethane resins and at least one acetal resin,
The thermal peeling force of the transfer layer is 0.4N or more and 0.8N or less.

In one embodiment, the release layer includes a high Tg urethane resin and a low Tg urethane resin,
The glass transition temperature of the high Tg urethane resin is 50°C or higher, and the glass transition temperature of the low Tg urethane resin is 10°C or lower.

In one embodiment, the content ratio of the high Tg urethane resin and the low Tg urethane resin (high Tg urethane resin/low Tg urethane resin) in the release layer is 5/30 or more and 30/5 or less on a mass basis.

In one embodiment, the content of the high Tg urethane resin in the release layer is 5% by mass or more and 35% by mass or less.

In one embodiment, the content of the low Tg urethane resin in the release layer is 3% by mass or more and 35% by mass or less.

In one embodiment, the glass transition temperature of the acetal resin in the release layer is 60°C or more and 120°C or less.

In one embodiment, the content of acetal resin in the release layer is 55% by mass or more and 90% by mass or less.

In one embodiment, the thickness of the release layer is 0.1 μm or more and 5 μm or less.

In one embodiment, the transfer layer includes a release layer below the melt transfer colorant layer.

In one embodiment, the release layer includes a (meth)acrylic resin and a vinyl resin.

In one embodiment, the release layer includes a release agent.

In one embodiment, the content of the release agent in the release layer is 0.1% by mass or more and 20% by mass or less.

A combination of a thermal transfer sheet and an intermediate transfer medium according to the present disclosure includes an intermediate transfer medium including the thermal transfer sheet, a second base material, and a receptor layer.

10: Thermal transfer sheet, 11: First base material, 12: Release layer, 13: Transfer layer, 14: Melt transfer type coloring material layer, 15: Peeling layer, 16: Sublimation transfer type coloring material layer, 17: Back layer , 20: Intermediate transfer medium, 21: Second base material, 22: Receptive layer

Claims (11)

comprising a first base material, a release layer, and a transfer layer including at least a melt-transferable coloring material layer;
The release layer includes at least a high Tg urethane resin and a low Tg urethane resin, and at least one type of acetal resin ,
The glass transition temperature of the high Tg urethane resin is 50°C or higher,
The glass transition temperature of the low Tg urethane resin is 10°C or less,
The glass transition temperature of the acetal resin is 60°C or more and 120°C or less,
A thermal transfer sheet, wherein the transfer layer having a width of 25 mm has a peeling force under heat of 0.4 N or more and 0.8 N or less. A content ratio of the high Tg urethane resin and the low Tg urethane resin (high Tg urethane resin/low Tg urethane resin) in the release layer is 5/30 or more and 30/5 or less on a mass basis. 1. The thermal transfer sheet according to 1 . The thermal transfer sheet according to claim 1 or 2 , wherein the content of the high Tg urethane resin in the release layer is 5% by mass or more and 35% by mass or less. The thermal transfer sheet according to any one of claims 1 to 3 , wherein the content of the low Tg urethane resin in the release layer is 3% by mass or more and 35% by mass or less. The thermal transfer sheet according to any one of claims 1 to 4 , wherein the content of the acetal resin in the release layer is 55% by mass or more and 90% by mass or less. The thermal transfer sheet according to any one of claims 1 to 5, wherein the thickness of the release layer is 0.1 μm or more and 5 μm or less. The thermal transfer sheet according to any one of claims 1 to 6 , wherein the transfer layer includes a release layer below the melt transfer type coloring material layer. The thermal transfer sheet according to claim 7 , wherein the release layer contains a (meth)acrylic resin and a vinyl resin (excluding the (meth)acrylic resin) . The thermal transfer sheet according to claim 7 or 8 , wherein the release layer contains a release material. The thermal transfer sheet according to claim 9 , wherein the content of the release agent in the release layer is 0.1% by mass or more and 20% by mass or less. A combination of the thermal transfer sheet according to any one of claims 1 to 10 and an intermediate transfer medium,
A combination of a thermal transfer sheet and an intermediate transfer medium, wherein the intermediate transfer medium includes a second substrate and a receptive layer.