JP2024066660A - Thermal transfer sheets and intermediate transfer media - Google Patents

Abstract

[Problem] To provide a thermal transfer sheet having good durability and foil tearability even when the protective layer is a single layer. [Solution] A thermal transfer sheet 1 includes a substrate 10, a release layer 20 provided on the substrate, and a protective layer 30 provided on the release layer. The release layer contains a binder resin, a polyester resin different from the binder resin, and a lubricating component. The mass of the polyester resin is 3% to 35% of the mass of the binder resin, and the mass of the lubricating component is 2% to 10% of the mass of the binder resin. The indentation elastic modulus of the protective layer is 3.5 gigapascals or more. [Selected Figure] Figure 1

Description

The present invention relates to a thermal transfer sheet and an intermediate transfer medium.

Conventionally, images such as gradation images, monotonous images such as characters and symbols have been formed on a substrate by using a thermal transfer method. As the thermal transfer method, a thermal sublimation transfer method and a thermal melt transfer method are widely used.
The transfer layer that is transferred to the transferee by the thermal transfer method can be provided with various functions by providing a coloring layer, an adhesive layer, a protective layer, etc. If the transfer layer is robust, it can also be used as a protective sheet.

On the other hand, image formation by a general thermal transfer method can be difficult depending on the surface shape of the transfer medium, etc. In such cases, an intermediate transfer method using an intermediate transfer medium is widely used.
For example, the thermal transfer sheet is heated to transfer the sublimable dye or pigment in the colored layer to the image-receiving layer of the intermediate transfer medium to form an image, and then the intermediate transfer medium is heated to transfer the transfer layer of the intermediate transfer medium onto the transferee. In this case, the transfer layer of the intermediate transfer medium becomes the outermost surface of the printed matter after printing.

Currently, with the diversification and widespread use of IC cards and the like, there is an increasing demand for physical durability (high abrasion resistance). In order to satisfy the demands in these fields, a method of imparting durability by attaching a patch made of PET (polyethylene terephthalate) to an IC card or the like on which an image is formed is well known. However, this method requires a separate device for attaching the PET patch, which is not preferable from the viewpoint of production process and cost.
For this reason, it is preferable to impart high durability to the transfer layer of a thermal transfer sheet or intermediate transfer medium. However, it is important to note that attempting to provide durability tends to cause the coating film to harden, which can lead to poor foil cutting properties and the production of burrs.

Several techniques have been disclosed for protecting printed matter using thermal transfer sheets or intermediate transfer media.
In Patent Document 1, a curable protective layer is provided on a substrate, and this curable protective layer has a multilayer structure in which multiple curable protective members of the same or different types each having a predetermined film thickness are laminated, thereby imparting durability to the transfer body while also ensuring foil cutting properties.

Patent Document 2 proposes an intermediate transfer medium in which a release layer, a protective layer, and a receiving layer/adhesive layer are provided on a substrate. With this intermediate transfer medium, when an image is formed, the protective layer is located on the surface of the transfer layer transferred to the transfer recipient, so that the transfer layer can be provided with durability.
Patent Document 3 proposes an intermediate transfer medium having a protective layer made of a cured acrylic polyol resin having a glass transition temperature (Tg) of more than 80° C. and a hydroxyl value of 10 mgKOH/g to 100 mgKOH/g. This intermediate transfer medium can provide durability to the protective layer while maintaining foil cutting properties.

JP 2001-1674 A JP 2004-351656 A JP 2014-198433 A

The thermal transfer sheet of Patent Document 1 has multiple protective layers, so it is necessary to laminate at least one more layer during coating. Furthermore, it is necessary to consider the adhesion between the laminated protective layers, which places significant restrictions on the resins that can be used and may lead to problems such as poor adhesion.
The intermediate transfer medium of Patent Document 2 does not sufficiently ensure foil cuttability, and there is a possibility that burrs may occur during transfer to a transfer-receiving body.
In the intermediate transfer medium of Patent Document 3, the materials used for the protective layer are limited, and when other layers are laminated, it is necessary to select materials that are compatible with the protective layer.

In light of the above, the present invention aims to provide a thermal transfer sheet and intermediate transfer medium that have good durability and foil cutting properties even when the protective layer is a single layer.

A first aspect of the present invention is a thermal transfer sheet comprising a substrate, a release layer provided on the substrate, and a protective layer provided on the release layer.
The release layer contains a binder resin, a polyester resin different from the binder resin, and a lubricating component.
The mass of the polyester resin is 3% or more and 35% or less of the mass of the binder resin, and the mass of the lubricating component is 2% or more and 10% or less of the mass of the binder resin.
The protective layer has an indentation elastic modulus of 3.5 gigapascals or more.

A second aspect of the present invention is an intermediate transfer medium comprising a substrate, a release layer provided on the substrate, a protective layer provided on the release layer, and a receiving layer provided on the protective layer.
The release layer contains a binder resin, a polyester resin different from the binder resin, and a lubricating component.
The mass of the polyester resin is 3% or more and 35% or less of the mass of the binder resin, and the mass of the lubricating component is 2% or more and 10% or less of the mass of the binder resin.
The protective layer has an indentation elastic modulus of 3.5 gigapascals or more.

The thermal transfer sheet and intermediate transfer medium of the present invention have good durability and foil cutting properties even though the protective layer is a single layer.

1 is a schematic cross-sectional view of a thermal transfer sheet according to one embodiment of the present invention. 1 is a schematic cross-sectional view of an intermediate transfer medium according to an embodiment of the present invention.

An embodiment of the present invention will be described with reference to FIG.
Fig. 1 is a schematic cross-sectional view showing a thermal transfer sheet 1 of the present embodiment. As shown in Fig. 1, the thermal transfer sheet 1 includes a substrate 10, a release layer 20, and a protective layer 30. The release layer 20 and the protective layer 30 are provided on a first surface 10a of the substrate 10.

The substrate 10 must have heat resistance and strength such that it does not soften or deform due to the heat and pressure used in thermal transfer printing. Examples of the substrate 10 include various plastic films or sheets such as polyesters such as polyethylene terephthalate, polyarylates, polycarbonates, polyurethanes, polyimides, polyetherimides, cellulose derivatives, polyethylene, ethylene-vinyl acetate copolymers, polypropylene, polystyrene, acrylics, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene-ethylene, tetrafluoroethylene-hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride.
The thickness of the substrate 10 can be appropriately set depending on the material so as to provide appropriate strength and heat resistance, and is generally 2.5 μm or more and 100 μm or less.

In the substrate 10, a second surface 10b opposite to the first surface 10a may be subjected to a treatment for imparting lubricity or heat resistance.
In the substrate 10, the first surface 10a on which the release layer 20 is formed can be subjected to an adhesion treatment. As the adhesion treatment, known techniques such as corona treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, plasma treatment, and primer treatment can be applied, and two or more of these treatments can be used in combination.

The release layer 20 is a layer containing a binder resin, a polyester resin, and a lubricating component.
The binder resin can be appropriately selected from known resins, and suitable examples include acrylic skeleton resins, vinyl chloride-vinyl acetate copolymers, cellulose acetate and thermosetting acrylic resins, melamine resins, nitrocellulose resins, etc. Among these, it is preferable to use an acrylic skeleton resin as the main component.
The inventors have found that the foil cutting property is greatly improved by adding a polyester resin to the release layer at a mass ratio of 3% to 35% relative to the binder resin. There is no particular restriction on the polyester resin used, but it is preferable that the Tg (glass transition point) is 40°C to 90°C. If the amount of polyester resin is 3% or less relative to the binder resin, the adhesion to the substrate is weak, the foil cutting property is poor, and burrs are likely to occur. On the other hand, if it is 35% or more, the adhesion to the substrate becomes too strong, making it difficult to peel. This makes it easy to cause appearance defects such as jamming, in which the substrate cannot be conveyed out of the printer and printing cannot be performed, or banding, in which thin lines appear perpendicular to the printing direction as a result of poor peeling.

Furthermore, the inventors have found that adding 2% to 10% of the lubricating component to the binder resin increases the lubricity, improves the abrasion resistance, and improves the foil cutting ability. If the lubricating component is 2% or less, the film becomes hard when peeled off, making the foil cutting ability poor, and the durability performance is somewhat inferior due to the low lubricity. On the other hand, if it is 10% or more, the film becomes soft when heated, weakening the adhesion to the substrate and worsening the foil cutting ability.
Examples of the lubricating component include various waxes such as polyethylene wax, paraffin wax, carnauba wax, higher aliphatic alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorine-based surfactants, organic carboxylic acids and derivatives thereof, fluorine-based resins, silicone resins, talc, particles of inorganic compounds such as silica, etc. Among these, various waxes such as polyethylene wax, paraffin wax, carnauba wax, higher aliphatic alcohols, and organopolysiloxanes are more preferred.

The release layer 20 may contain a filler. Various known fillers can be used, and examples of such fillers include silicone particles, silica particles, melamine particles, and acrylic particles. From the viewpoints of detachment during transfer and film formation, the particle size of the filler is preferably about 0.01 μm or more and 3 μm or less.
In this specification, the "particle size of the filler" means the volume average particle size. The particle size of the filler can be measured, for example, by the BET method or by analyzing the results of observation under an electron microscope using image analysis type particle size distribution measurement software.
Incidentally, fillers having particle sizes outside the above range may be contained in part as long as the effect of the fillers is not impaired.
There is no limitation on the amount of the filler contained, but from the viewpoint of foil cutting properties, the amount of the filler contained is preferably 0.5% to 25% based on the binder resin.

The protective layer 30 is a layer made of a cured synthetic resin, and either a thermoplastic resin or a thermosetting resin can be used as long as it satisfies the indentation elastic modulus described below. Examples of the thermoplastic resin include acrylic resin, epoxy resin, polyester resin, polycarbonate resin, etc. Examples of the thermosetting resin include polyurethane resin, phenol resin, melamine resin, epoxy resin, silicone resin, alkyd resin, etc.
In addition, it can also be formed from a photocurable resin such as ultraviolet-curable urethane acrylate or epoxy acrylate.
The thickness of the protective layer 30 can be appropriately set within a range that does not adversely affect durability and foil cuttability, and can be, for example, 0.5 μm or more and 5 μm or less.

The protective layer 30 may contain a filler. The material and particle size of the filler can be the same as those described for the release layer 20. It is preferable that the filler content is 0.5% or more and 25% or less of the base resin constituting the protective layer.

After much investigation, the inventors discovered that by setting the indentation elastic modulus of the protective layer to 3.5 gigapascals (GPa) or more, even if the protective layer is a single layer, it is possible to achieve both good durability and good foil tearability in combination with the above-mentioned release layer.
The indentation modulus of the protective layer is greatly affected by the base resin of the protective layer, and is likely to be 3.5 GPa or more when the base resin is a thermosetting resin or a photocurable resin having a crosslinked structure. The indentation modulus also varies slightly depending on the amount of filler added, and the value of the indentation modulus tends to increase when the amount of filler is increased.

In this embodiment, an example of a thermal transfer sheet having only a release layer and a protective layer on a substrate has been described. A thermal transfer sheet having such a configuration can provide a protective layer on an image receiving sheet on which a transfer image has already been formed. As another configuration, a thermal transfer sheet can be provided in which the formation of a transfer image and the provision of a protective layer can be carried out continuously by repeatedly providing a pair of a release layer and a protective layer on the substrate and a layer for forming a transfer image such as a color pigment layer.

Figure 2 shows a schematic cross-sectional view of the intermediate transfer medium 2 according to this embodiment. The intermediate transfer medium 2 has a configuration generally similar to that of the thermal transfer sheet 1, except that it has a receiving layer 40 provided on a protective layer 30. In other words, the same materials as those in the thermal transfer sheet 1 can be used for the substrate 10, the release layer 20, and the protective layer 30.

The receiving layer 40 constitutes the uppermost layer of the intermediate transfer medium 2, and is also the layer on which the thermal transfer image is formed. The receiving layer 40 on which the image is formed is transferred onto the transfer target together with the protective layer 30 and the peeling layer 20, and a print is formed in a state protected by the protective layer 30 and the peeling layer 20.

As a material for forming the receiving layer 40, a conventionally known resin that readily receives a thermally transferable coloring material such as a sublimable dye or a thermally meltable transfer ink can be used.
Resins constituting the receiving layer 40 include polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride or polyvinylidene chloride, vinyl resins such as polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers or polyacrylic esters, polyester resins such as polyethylene terephthalate or polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene or propylene with other vinyl polymers, cellulose resins such as ionomers or cellulose diastase, polycarbonates, epoxy resins, etc., and in particular, vinyl chloride resins, acrylic-styrene resins or polyester resins are preferred for transfer using a dye-sublimation type thermal transfer ribbon, and epoxy resins are preferred for transfer using a melt type thermal transfer ribbon.

When the receiving layer 40 is transferred to the receiving body via an adhesive layer, the receiving layer 40 itself does not necessarily need to be adhesive. However, when the receiving layer 40 is transferred to the receiving body without an adhesive layer, it is preferable to form the receiving layer 40 using a resin having adhesive properties.

The receiving layer 40 can be formed by dissolving or dispersing a coating liquid for the receiving layer in an appropriate solvent such as water or an organic solvent using one or more materials selected from the above-mentioned materials, and adding various additives as necessary, and applying the coating liquid by a solvent coating method such as bar coating, blade coating, air knife coating, gravure coating, or roll coating, and drying. The thickness of the receiving layer 40 may be from 0.1 μm to 10 μm, and preferably from 0.2 μm to 8 μm.

When the receiving layer 40 does not have adhesive properties, an adhesive layer may be further provided on the receiving layer 40. The adhesive layer is an optional configuration, and is not necessary when an adhesive treatment is applied to the transfer-receiving body side.
The resin constituting the adhesive layer may be a conventional adhesive whose main component is an acrylic resin, a vinyl resin, a polyester resin, a urethane resin, a polyamide resin, an epoxy resin, a rubber resin, an ionomer resin, or the like.

The thermal transfer sheet and intermediate transfer medium of the present invention will be further described using examples and comparative examples. The present invention is not limited solely by the specific contents of the examples and comparative examples.
In the text, "parts" means parts by mass unless otherwise specified.

Example 1
A 12 μm-thick polyethylene terephthalate film was used as the substrate, and one side of the film was coated with release layer coating solution 1 having the following composition so that the film thickness after drying would be 0.5 μm. The film was then dried at 100° C. for 1 minute to form a release layer.
<Coating solution 1 for release layer>
Binder resin: 79 parts of acrylic resin (Paraloid A21, manufactured by Dow) and 8 parts of polyester resin (Vylon 20SS, manufactured by Toyobo Co., Ltd.) (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2, manufactured by Gifu Seratsuku Co., Ltd.) 13 parts (solid content 15%)
・Methyl ethyl ketone 350 parts

Next, protective layer coating solution A having the following composition was applied onto the release layer so that the film thickness after drying would be 2.0 μm, and then dried at 100° C. for 1 minute.
<Coating Solution A for Protective Layer>
Base resin: Acrylic polyol (6AN-5000, manufactured by Taisei Fine Chemical Co., Ltd.) 81 parts (solid content 40.5%)
Polyisocyanate (Takenate D-110, manufactured by Mitsui Chemicals) 12 parts (solid content 70%)
Silicone filler (Tospearl 120 (particle size 2.0 μm) manufactured by Momentive Corporation) 3 parts Polyester resin (Vylon UR-1400 manufactured by Toyobo Co., Ltd.) 3 parts (solid content 30%)
Ethyl acetate 40 parts By the above, a thermal transfer sheet having a release layer and a protective layer provided on a substrate according to Example 1 was produced. The coating liquid for the release layer and the coating liquid for the protective layer were both applied by gravure coating.

Example 2
A thermal transfer sheet according to Example 2 was produced in the same manner as in Example 1, except that Coating Solution 2 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 2 for release layer>
Binder resin: acrylic resin (Paraloid A21) 79 parts, polyester resin (Vylon 20SS) 8 parts (solid content 30%)
Slippery component: Paraffin wax (HNP-3, manufactured by Nippon Seiro Co., Ltd.) 2 parts, methyl ethyl ketone 350 parts

Example 3
A thermal transfer sheet according to Example 3 was produced in the same manner as in Example 1, except that Coating Solution 3 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 3 for release layer>
Binder resin: acrylic resin (Paraloid A21) 79 parts, polyester resin (Vylon 20SS) 83 parts (solid content 30%)
Lubricating component: Silicone oil (DOWSIL BY16-846, manufactured by Dow Corning Toray Co., Ltd.) 2 parts, Methyl ethyl ketone 350 parts

Example 4
The thermal transfer sheet of Example 4 was prepared in the same manner as in Example 1, except that Coating Liquid 4 for the Release Layer, having the following composition, was used instead of Coating Liquid 1 for the Release Layer, and Coating Liquid B for the Protective Layer, having the following composition, was used instead of Coating Liquid A for the Protective Layer.
<Coating solution 4 for release layer>
Binder resin: acrylic resin (Paraloid A21) 79 parts, polyester resin (Vylon 20SS) 8 parts (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 44 parts (solid content 15%)
Methyl ethyl ketone 350 parts <Protective layer coating solution B>
Base resin: Acrylic polyol (6AN-5000) 81 parts (solid content 40.5%)
Polyisocyanate (Takenate D-110) 12 parts (solid content 70%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 7.5 parts Polyester resin (Vylon UR-1400, manufactured by Toyobo Co., Ltd.) 3 parts (solid content 30%)
40 parts ethyl acetate

Example 5
A thermal transfer sheet according to Example 5 was produced in the same manner as in Example 1, except that protective layer coating solution C having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution C>
Base resin: 48 parts of acrylic polyol (URET422, manufactured by Toyo Ink Co., Ltd.) (solid content 35%)
Polyisocyanate (Takenate D-110) 12 parts (solid content 70%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 3 parts Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
40 parts ethyl acetate

Example 6
A thermal transfer sheet according to Example 6 was produced in the same manner as in Example 1, except that protective layer coating solution D having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution D>
Base resin: 120 parts of acrylic resin (TM-REX, Dainichi Seika Chemicals Co., Ltd.) (solid content 25%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 3 parts Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
40 parts ethyl acetate

(Example 7)
A thermal transfer sheet according to Example 7 was produced in the same manner as in Example 1, except that protective layer coating solution E having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution E>
Base resin: urethane acrylate (oligomer O27, manufactured by Toyo Ink Co., Ltd.) 52 parts, acrylate monomer (DPHA, manufactured by Daicel Corporation) 13 parts, photopolymerization initiator (Irgacure 184, manufactured by BASF Corporation) 6 parts, photopolymerization initiator (Irgacure 907, manufactured by BASF Corporation) 1 part, ethyl acetate 28 parts

(Example 8)
A thermal transfer sheet according to Example 8 was produced in the same manner as in Example 1, except that protective layer coating solution F having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution F>
Base resin: Acrylic polyol (6AN-5000) 81 parts (solid content 40.5%)
Polyisocyanate (Takenate D-110) 12 parts (solid content 70%)
Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
40 parts ethyl acetate

Example 9
A thermal transfer sheet according to Example 9 was produced in the same manner as in Example 1, except that the thickness of the protective layer was 0.5 μm.
Example 10
A thermal transfer sheet according to Example 10 was produced in the same manner as in Example 1, except that the thickness of the protective layer was 6.0 μm.

(Example 11)
A thermal transfer sheet according to Example 11 was produced in the same manner as in Example 1, except that Coating Solution 5 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 5 for release layer>
Binder resin: acrylic resin (Paraloid A21) 79 parts, polyester resin (Vylon 20SS) 8 parts (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 13 parts (solid content 15%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 3 parts Methyl ethyl ketone 350 parts

Example 12
A thermal transfer sheet according to Example 12 was produced in the same manner as in Example 1, except that protective layer coating solution G having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution G>
Base resin: Acrylic polyol (6AN-5000) 81 parts (solid content 40.5%)
Polyisocyanate (Takenate D-110) 12 parts (solid content 70%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 1.5 parts Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
40 parts ethyl acetate

Examples 13 and 14 are examples of intermediate transfer media.
(Example 13)
A receiving layer coating solution having the following composition was applied onto the protective layer of the thermal transfer sheet of Example 1 so that the film thickness after drying would be 3.0 μm, and then dried at 100° C. for 1 minute.
<Coating solution for receiving layer>
Epoxy resin (jER1004 manufactured by Mitsubishi Chemical Corporation) 20 parts Methyl ethyl ketone 80 parts In this manner, an intermediate transfer medium according to Example 13 was prepared.
(Example 14)
An intermediate transfer medium according to Example 14 was prepared in the same manner as in Example 13, except that the above-mentioned receiving layer coating liquid was applied onto the protective layer of the thermal transfer sheet according to Example 11.

(Comparative Example 1)
A thermal transfer sheet according to Comparative Example 1 was produced in the same manner as in Example 1, except that Coating Solution 6 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 6 for release layer>
Binder resin: 79 parts of acrylic resin (Paraloid A21) and 5.5 parts of polyester resin (Vylon 20SS) (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 13 parts (solid content 15%)
・Methyl ethyl ketone 350 parts

(Comparative Example 2)
A thermal transfer sheet according to Comparative Example 2 was produced in the same manner as in Example 1, except that Coating Solution 7 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 7 for release layer>
Binder resin: 79 parts of acrylic resin (Paraloid A21) and 94.5 parts of polyester resin (Vylon 20SS) (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 13 parts (solid content 15%)
・Methyl ethyl ketone 350 parts

(Comparative Example 3)
A thermal transfer sheet according to Comparative Example 3 was produced in the same manner as in Example 1, except that Coating Solution 8 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 8 for release layer>
Binder resin: acrylic resin (Paraloid A21) 79 parts, polyester resin (Vylon 20SS) 8 parts (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 7 parts (solid content 15%)
・Methyl ethyl ketone 350 parts

(Comparative Example 4)
A thermal transfer sheet according to Comparative Example 4 was produced in the same manner as in Example 1, except that Coating Solution 9 for Release Layer having the following composition was used instead of Coating Solution 1 for Release Layer.
<Coating solution 9 for release layer>
Binder resin: 79 parts of acrylic resin (Paraloid A21) and 8 parts of polyester resin (Vylon 20SS) (solid content 30%)
Slippery component: Polyethylene wax (Hiflat T-15P-2) 54.6 parts (solid content 15%)
・Methyl ethyl ketone 350 parts

(Comparative Example 5)
A thermal transfer sheet according to Comparative Example 5 was produced in the same manner as in Example 1, except that protective layer coating solution H having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution H>
Base resin: Epoxy resin (jER1004) 20 parts Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 3 parts Ethyl acetate 40 parts

(Comparative Example 6)
A thermal transfer sheet according to Comparative Example 6 was prepared in the same manner as in Example 1, except that protective layer coating solution I having the following composition was used instead of protective layer coating solution A.
<Protective Layer Coating Solution I>
Base resin: Acrylic polyol (6AN-5000) 81 parts (solid content 40.5%)
Polyisocyanate (Takenate D-110) 12 parts (solid content 70%)
Silicone filler (Tospearl 120 (particle size 2.0 μm)) 10 parts Polyester resin (Vylon UR-1400) 3 parts (solid content 30%)
40 parts ethyl acetate

The following evaluations were carried out using the thermal transfer sheet and intermediate transfer medium of each example.

<Measurement of indentation elastic modulus of protective layer>
For a film in which a release layer and a protective layer were applied to a substrate, measurements were performed from the protective layer side using a nanoindenter (Hysitron TI Premier (manufactured by Bruker)) as a tester and a diamond Berkovich indenter at a maximum depth of 400 nm, a push-in/pull-out speed of 100 nm/s, and a holding time at the maximum depth of 4 seconds. Analysis was performed using the Oliver-Pharr method in the range of 95-60% load during pulling. Note that the influence of the substrate and the release layer on this measurement is extremely small and can be ignored.

<Creating Transcripts>
The thermal transfer sheet of each example was placed on a polyvinyl chloride card (54 mm×86 mm), and the protective layer and release layer were transferred onto the card using a thermal simulator.
For the intermediate transfer medium of Example 11, an arbitrary thermal transfer sheet was superimposed, an image was formed on the receiving layer using a thermal simulator, and then the sheet was superimposed on a polyvinyl chloride card (54 mm x 86 mm), and the receiving layer, protective layer, and release layer were transferred onto the card using a thermal simulator.
As a result of the above, the transcripts according to the respective examples were obtained. Using these transcripts, the following evaluations were carried out.
<Foil cuttability>
Using a digital microscope VHX-1000 manufactured by Keyence Corporation, the maximum protruding length of burrs at the ends of 10 transferred sheets of each example was measured.
The evaluation was made on the following three levels, with ⊚ and ○ being acceptable.
⊚ (VERY GOOD): The maximum protruding length of the burrs is less than 100 μm ◯ (GOOD): The maximum protruding length of the burrs is 100 μm or more and less than 300 μm × (BAD): The maximum protruding length of the burrs is 300 μm or more <Durability (Taber abrasion test)>
The transferred material according to each example was subjected to a Taber test in accordance with JIS K 7204. The test environment was as follows.
An abrasive wheel (CF-10F, manufactured by Toyo Seiki Co., Ltd.) was placed in a test machine (rotary abrasion tester, manufactured by Toyo Seiki Co., Ltd.) Test conditions: 500 gf, rotation speed 60 rpm
The evaluation was made on the following three levels, with ⊚ and ○ being acceptable.
⊚ (Very Good): No scratches were observed on the surface of the transferred material after 1000 rotational abrasions.
◯ (GOOD): No scratches were observed on the surface of the transferred material after 800 rotational abrasions.
× (BAD): Scratches were generated on the surface of the transferred material after less than 800 rotational abrasions.
<Transferability>
The thermal transfer sheet and intermediate transfer medium according to each example were printed on a vinyl chloride card by a printer, and the printer operability and transfer appearance were confirmed. The evaluation criteria were based on the following two levels, with ◯ being acceptable.
◯ (GOOD): The transferred material was ejected from the printer without any problems (printer operation was normal), and there was no abnormality in the appearance of the transfer. × (BAD): The transferred material was not ejected from the printer (jamming) or there was an abnormality in the appearance of the transfer. The results of the examples are shown in Table 1, and the results of the comparative examples are shown in Table 2.

As shown in Table 1, in each example in which the release layer contains polyester and a slipping component in addition to the binder resin, and the polyester is 3% or more and 35% or less of the binder resin, and the slipping component is 2% or more and 10% or less of the binder resin, the indentation elastic modulus of the protective layer is 3.5 GPa or more, and the film has sufficient durability and tearability.

In Comparative Example 1 shown in Table 2, the amount of polyester resin in the release layer was small, so the adhesion between the release layer and the substrate was weak. For this reason, the film was peeled off to the periphery of the area to be transferred during transfer, which is thought to have resulted in a decrease in foil cutting ability.
In Comparative Example 2, the amount of polyester resin in the release layer was large, and the adhesion between the release layer and the substrate was excessively strong, which resulted in jamming during transport within the printer as the release layer could not be peeled off from the substrate, and the transferability was reduced.
In Comparative Example 3, the amount of the lubricating component in the release layer was small, so the film became hard and was difficult to peel off, resulting in poor foil cutting properties.
In Comparative Example 4, the amount of the lubricating component in the release layer was too large, so that the film was excessively softened when heated, and peeling was easy. As a result, the foil cutting property was not good.
In Comparative Example 5, the protective layer had a low indentation elastic modulus and was not durable.
In Comparative Example 6, the amount of filler in the protective layer was too large, making it difficult to form the protective layer, and therefore the indentation modulus, foil tearability, durability, and transferability could not be evaluated.

Although one embodiment of the present invention has been described above, the specific configuration is not limited to this embodiment, and configuration changes and combinations that do not deviate from the gist of the present invention are also included.

1 Thermal transfer sheet 2 Intermediate transfer medium 10 Substrate 20 Release layer 30 Protective layer 40 Receptive layer

Claims (10)

A substrate;
A release layer provided on the substrate;
a protective layer provided on the release layer;
Equipped with
The release layer is
The adhesive composition includes a binder resin, a polyester resin different from the binder resin, and a lubricating component,
The mass of the polyester resin is 3% or more and 35% or less of the mass of the binder resin,
The mass of the lubricating component is 2% or more and 10% or less of the mass of the binder resin,
The indentation elastic modulus of the protective layer is 3.5 gigapascals or more.
Thermal transfer sheet. The protective layer contains a base resin and a filler,
The mass of the filler is 0.5% or more and 25% or less of the mass of the base resin.
The thermal transfer sheet according to claim 1 . The release layer contains a filler,
The mass of the filler is 0.5% or more and 25% or less of the mass of the binder resin.
The thermal transfer sheet according to claim 1 . The lubricating component includes at least one of wax, higher aliphatic alcohol, and organopolysiloxane.
The thermal transfer sheet according to claim 1 . The thickness of the protective layer is 0.5 μm or more and 5.0 μm or less.
The thermal transfer sheet according to claim 1 . A substrate;
A release layer provided on the substrate;
a protective layer provided on the release layer;
a receiving layer provided on the protective layer;
Equipped with
The release layer is
a thermal transfer pigment layer formed on the substrate, the thermal transfer pigment layer including a binder resin, a polyester resin different from the binder resin, and a lubricating component;
The mass of the polyester resin is 3% or more and 35% or less of the mass of the binder resin,
The mass of the lubricating component is 2% or more and 10% or less of the mass of the binder resin,
The indentation elastic modulus of the protective layer is 3.5 gigapascals or more.
Intermediate transfer medium. The protective layer contains a base resin and a filler,
The mass of the filler is 0.5% or more and 25% or less of the mass of the base resin.
The intermediate transfer medium of claim 6. The release layer contains a filler,
The mass of the filler is 0.5% or more and 25% or less of the mass of the binder resin.
The intermediate transfer medium of claim 6. The lubricating component includes at least one of wax, higher aliphatic alcohol, and organopolysiloxane.
The intermediate transfer medium of claim 6. The thickness of the protective layer is 0.5 μm or more and 5.0 μm or less.
The intermediate transfer medium of claim 6.

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