Thermal transfer sheet, method for manufacturing a thermal transfer sheet, and method for manufacturing a printed object.

Abstract

We provide a heat transfer sheet with excellent durability and heat resistance. [Solution] A heat transfer sheet comprising a base material and a transfer layer, wherein the transfer layer comprises a colorant layer, and the colorant layer comprises a colorant and a resin component that forms urethane bonds by heating and hardens by ultraviolet irradiation, or an acrylic resin containing acryloyl groups and carboxyl groups that forms ester bonds by heat curing, wherein the ultraviolet transmittance of the transfer layer at a wavelength of 365 nm and the ultraviolet transmittance at a wavelength of 395 nm are 20% or more.

Description

Technical Field

[0001] The present invention relates to a thermal transfer sheet, a method for manufacturing the thermal transfer sheet, and a method for manufacturing a printed matter.

Background Art

[0002] Conventionally, with respect to a thermal transfer sheet including a base material and a colorant layer, energy is applied using a thermal head or the like, and the colorant layer is transferred onto a transfer target such as a thermal transfer image receiving sheet to form an image and obtain a printed matter. A thermal melting transfer method is known.

[0003] In a thermal transfer sheet (melting ribbon) used in the thermal melting transfer method, chemical resistance (durability) and heat resistance are required, and a UV curable resin is used as a resin component constituting the colorant layer. (For example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the thermal transfer sheet disclosed in Patent Document 1, the colorant layer contains a pigment in addition to the UV curable resin. When irradiating ultraviolet rays, the pigment absorbs a part of the ultraviolet rays, so the resin is not sufficiently cured, and there is a problem that sufficient durability and heat resistance cannot be obtained.

[0006] An object of the present disclosure is to provide a thermal transfer sheet excellent in durability and heat resistance. Another object of the present disclosure is to provide a method for manufacturing a thermal transfer sheet excellent in durability and heat resistance, and a method for manufacturing a printed matter.

Means for Solving the Problems

[0007] The thermal transfer sheet of this disclosure comprises a substrate and a transfer layer, The transfer layer comprises a colorant layer, The aforementioned colorant layer is Colorants and, A resin component that forms urethane bonds upon heating and hardens upon ultraviolet irradiation. Or, An acrylic resin containing acryloyl groups and carboxyl groups, which forms ester bonds upon thermal curing, and The ultraviolet transmittance of the transfer layer at a wavelength of 365 nm and the ultraviolet transmittance at a wavelength of 395 nm are both 20% or more. [Effects of the Invention]

[0008] According to this disclosure, a heat transfer sheet with excellent durability and heat resistance can be provided. Furthermore, this disclosure provides a method for manufacturing a thermal transfer sheet with excellent durability and heat resistance, and a method for manufacturing a printed image. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below. This disclosure can be implemented in many different forms and is not construed as being limited to the embodiments described below. The drawings may schematically represent the width, thickness, and shape of each layer, etc., compared to the embodiments, in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In this specification and in each figure, elements similar to those already described in the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0010] In this disclosure, if there are multiple candidate upper limits and multiple candidate lower limits for a certain parameter, the numerical range of that parameter may be constructed by combining any one candidate upper limit and any one candidate lower limit. Examples of such parameters include physical properties, component content, and layer thickness. As an example, let's consider the statement, "Parameter B is preferably A1 or higher, more preferably A2 or higher, and even more preferably A3 or higher. Parameter B is preferably A4 or lower, more preferably A5 or lower, and even more preferably A6 or lower." In this example, the numerical range of parameter B may be A1 or higher and A4 or lower, A1 or higher and A5 or lower, A1 or higher and A6 or lower, A2 or higher and A4 or lower, A2 or higher and A5 or lower, A2 or higher and A6 or lower, A3 or higher and A4 or lower, A3 or higher and A5 or lower, and A3 or higher and A6 or lower.

[0011] In this specification, each component (for example, resin material and additives such as colorants) mentioned in the following description may be used individually or in combination of two or more.

[0012] <Heat Transfer Sheet> The thermal transfer sheet of this disclosure comprises a substrate and a transfer layer provided on the substrate, the transfer layer comprising at least a colorant layer. The thermal transfer sheet may have multiple colorant layers arranged sequentially on the substrate (not shown). In one embodiment, the transfer layer may be configured to include a release layer as a layer located on the substrate side. In one embodiment, the thermal transfer sheet may have a back layer on the side of the substrate opposite to the side on which the transfer layer is provided. The following describes each layer of the thermal transfer sheet provided by this disclosure.

[0013] (base material) The substrate can be used without restriction, as long as it has heat resistance to the thermal energy applied during thermal transfer and mechanical strength and solvent resistance to support the transfer layer and the like provided on the substrate.

[0014] A film made of resin material (hereinafter simply referred to as "resin film") can be used as the base material. Examples of resin materials include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), 1,4-polycyclohexylenedimethylene terephthalate and terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer; polyamides such as nylon 6 and nylon 6,6; polyolefins such as polyethylene (PE), polypropylene (PP), and polymethylpentene; vinyl resins such as polyvinyl chloride, polyvinyl alcohol (PVA), polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and polyvinylpyrrolidone (PVP); (meth)acrylic resins such as polyacrylate and polymethacrylate; imide resins such as polyimide and polyetherimide; cellophane; cellulose resins such as cellulose acetate, nitrocellulose, cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB); styrene resins such as polystyrene (PS); polycarbonates; and ionomer resins. Among the resin materials mentioned above, polyester is preferred from the viewpoint of heat resistance and mechanical strength, PET or PEN is more preferred, and PET is particularly preferred. In this disclosure, "(meth)acrylic" includes both "acrylic" and "methacrylic." Similarly, "(meth)acrylate" includes both "acrylate" and "methacrylate."

[0015] The resin film laminates described above can also be used as a substrate. The resin film laminates can be manufactured using methods such as dry lamination, wet lamination, or extrusion.

[0016] When the base material is a resin film, the resin film may be either a stretched film or an unstretched film. From the viewpoint of strength, a stretched film stretched in one or two axes is preferred.

[0017] The thickness of the base material is preferably 2 μm or more and 25 μm or less, and more preferably 3 μm or more and 16 μm or less. Thereby, the mechanical strength of the base material and the transfer of thermal energy during thermal transfer can be improved.

[0018] (Transfer layer) The thermal transfer sheet of the present disclosure includes a transfer layer, and the transfer layer includes at least a coloring material layer. In one embodiment, the transfer layer may include a release layer as a layer located on the base material side.

[0019] In the thermal transfer sheet of the present disclosure, either the ultraviolet transmittance at a wavelength of 365 nm or the ultraviolet transmittance at a wavelength of 395 nm of the transfer layer is 20% or more. Thereby, the polymerization reaction by irradiating ultraviolet rays on the transfer layer after transfer onto the transfer object can proceed well, and by forming a hard layer, the scratch resistance and solvent resistance of the printed matter can be improved.

[0020] In the present disclosure, the ultraviolet transmittance is a value measured by an apparatus in which an integrating sphere attachment device (manufactured by Shimadzu Corporation, ISR-3100) is attached to an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC). More specifically, first, prepare the thermal transfer sheet of the present disclosure and place it on the sample light beam side of the ultraviolet-visible spectrophotometer. Next, transfer the transfer layer of the thermal transfer sheet onto an arbitrary transfer object, place the thermal transfer sheet after the transfer layer is transferred on the reference light beam side as a blank, and measure the ultraviolet transmittance. Thereby, the ultraviolet transmittance of the transfer layer can be measured.

[0021] The thickness of the transfer layer is preferably 0.1 μm or more and 2.5 μm or less, more preferably 0.2 μm or more and 2.0 μm or less, and particularly preferably 0.5 μm or more and 2.0 μm or less. Thereby, the solvent resistance and scratch resistance of the printed matter can be further improved.

[0022] (Coloring material layer) The colorant layer contains at least one colorant. The colorant can be used without restriction as long as it can satisfy the ultraviolet transmittance of the transfer layer, and may be a pigment or a dye.

[0023] Examples of colorants include black, white, yellow, blue, red, and green colorants. From the viewpoint of ultraviolet transmittance of the transfer layer, red or blue colorants are preferred, and red colorants are particularly preferred. Among red colorants, azo pigments are particularly preferred from the viewpoint of ultraviolet transmittance, and soluble azo pigments are particularly preferred. Azo pigments are pigments that contain an azo group (-N≡N-) in their molecular structure. Examples of commercially available azo pigments include 8040 Red (PR48:1), Seika First Red 1547 (PR48:2), and Seika First Carmine (PR57:1) (all manufactured by Dainichi Seika).

[0024] The colorant content in the colorant layer is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 40% by mass or less. This improves the density of the image formed by the transfer of the transfer layer.

[0025] The colorant layer includes a resin component that forms urethane bonds upon heating and hardens upon ultraviolet irradiation, or an acrylic resin containing acryloyl groups and carboxyl groups that forms ester bonds upon thermal curing. By transferring such a colorant layer onto a transfer substrate and then curing it by ultraviolet irradiation or thermal curing, the solvent resistance and abrasion resistance of the printed material can be improved.

[0026] In this disclosure, "resin components that form urethane bonds by heating and harden by ultraviolet irradiation (hereinafter also simply referred to as "resin components")" means monomers and oligomers that contain isocyanate groups (NCO groups), hydroxyl groups (OH groups), and acrylic groups in the structure of the resin, and when manufacturing a heat transfer sheet, during the drying process when the transfer layer is applied to the substrate using gravure printing, the NCO groups and OH groups react to form urethane bonds and heat harden, and after the transfer layer is transferred to the object to be transferred, it is irradiated with UV light in the printer, causing the acrylic groups to react and harden with UV light. In this disclosure, "oligomer" means a polymer with a degree of polymerization of 10 or less that is UV-curable.

[0027] Examples of "resin components" include polymer acrylates. Examples of polymer acrylates include urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, polyethylene acrylate, silicone acrylate, and polyol acrylate. Additionally, these methacrylates, itaconates, crotonates, and maleates can also be used. More specifically, examples include acrylates utilizing high molecular weight materials, acrylic resin acrylates, radical-curable acrylic polymers containing acrylic groups (acryloyl groups) and carboxyl groups, urethane acrylates containing NCO groups and OH groups, aromatic urethane acrylates, aliphatic urethane acrylates, and polyfunctional modified isocyanurate acrylates.

[0028] Furthermore, in this disclosure, "acrylic resin containing acryloyl groups and carboxyl groups and forming ester bonds by thermosetting" refers to the above-mentioned radical-curable acrylic polymer, which can also be used in combination with a polyfunctional UV resin.

[0029] The sum of the resin components or acrylic resin content in the colorant layer is preferably 50% by mass or more and 98% by mass or less, and more preferably 60% by mass or more and 90% by mass or less. This improves the solvent resistance and abrasion resistance of the printed material, as well as the fine line printing performance and blocking resistance of the thermal transfer sheet.

[0030] In one embodiment, the colorant layer may further contain one or more other resin materials. Examples of resin materials include (meth)acrylic resin, polyester, vinyl resin, cellulose resin, imide resin, styrene resin, polycarbonate, ionomer resin, and UV-curable resin. Among these, UV-curable resin is preferred from the viewpoint of solvent resistance and abrasion resistance of the printed material, and (meth)acrylic resin having unsaturated bonds is particularly preferred. Examples of unsaturated bonds include (meth)acryloyl groups and (meth)acryloyloxy groups.

[0031] In one embodiment, the colorant layer includes at least one photopolymerization initiator. This allows the polymerization reaction induced by ultraviolet irradiation of the transfer layer transferred onto the transfer substrate to proceed more effectively, and further improves the solvent resistance of the printed material. Examples of photopolymerization initiators include acetophenone, benzophenone, α-hydroxyalkylphenone, particulate ketones, benzoin, benzyldimethylketal, benzoylbenzoate, α-acyloxime esters, and thioxanthone compounds.

[0032] The content of the photopolymerization initiator in the colorant layer is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 10% by mass or less. This allows the polymerization reaction by ultraviolet irradiation of the transfer layer transferred onto the transfer substrate to proceed more smoothly, and the solvent resistance of the printed material can be further improved.

[0033] In one embodiment, the colorant layer may contain one or more types of particles. This can further improve the scratch resistance of the printed material. The particles may be organic particles, inorganic particles, or a combination of both. As organic particles, particles composed of resin materials can be used. Examples of resin materials include melamine resin, benzoguanamine resin, (meth)acrylic resin, polyamide, fluororesin, phenolic resin, styrene resin, polyolefin, and silicone resin. Examples of 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, oxides such as silica, graphite, saltpeter, and boron nitride.

[0034] The particle content in the colorant layer is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 10% by mass or less. This allows for further improvement of the scratch resistance of the printed material while maintaining the transferability of the transfer layer.

[0035] The colorant layer may contain additives. Examples include fillers, plasticizers, antistatic agents, UV absorbers, release agents, and dispersants.

[0036] The thickness of the colorant layer is preferably 0.1 μm to 2.5 μm, more preferably 0.2 μm to 2.3 μm, and particularly preferably 0.5 μm to 2.0 μm. This further improves the solvent resistance and abrasion resistance of the printed material.

[0037] The colorant layer can be formed by dispersing or dissolving the above-mentioned materials in a suitable solvent to create a coating solution, applying it to a substrate or the like to form a coating film, and then drying it. Known methods such as the roll coating method, reverse roll coating method, gravure coating method, reverse gravure coating method, bar coating method, or rod coating method can be used as coating methods.

[0038] (Exfoliation layer) In one embodiment, the release layer contains at least one type of wax. Examples of waxes include natural waxes such as beeswax, whale wax, wood wax, rice bran wax, carnauba wax, candelilla wax, and montane wax; synthetic waxes such as paraffin wax, microcrystalline wax, oxide wax, ozokerite, ceresin, ester wax, and polyethylene wax; higher saturated fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, furoic acid, and behenic acid; higher saturated monohydric alcohols such as stearyl alcohol and behenyl alcohol; higher esters such as sorbitan fatty acid esters; and higher fatty acid amides such as stearic acid amide and oleic acid amide.

[0039] The wax content in the release layer is, for example, 70% by mass or more and 99% by mass or less.

[0040] In one embodiment, the release layer includes the above-mentioned additive.

[0041] The thickness of the release layer is preferably 0.1 μm to 1 μm, and more preferably 0.2 μm to 0.6 μm. This improves image formation for transfer subjects with low smoothness and image formation for transfer subjects with high smoothness, as well as improving the transferability of the transfer layer.

[0042] The release layer can be formed by dispersing or dissolving the above material in a suitable solvent to create a coating solution, applying it to the substrate using the above coating means to form a coating film, and then drying it.

[0043] (back layer) In one embodiment, the heat transfer sheet of the present disclosure may have a back layer on the side of the substrate where the transfer layer is not provided. This makes it possible to suppress the occurrence of sticking and wrinkles due to heating during heat transfer.

[0044] In one embodiment, the back layer includes a resin material. Examples include cellulose resin, styrene resin, vinyl resin, polyester, polyurethane, silicone-modified polyurethane, fluorine-modified polyurethane, and (meth)acrylic resin.

[0045] In one embodiment, the back layer contains a two-component curing resin that hardens when used in combination with an isocyanate compound or the like. Examples of such resins include polyvinyl acetals such as polyvinyl acetal and polyvinyl butyral.

[0046] In one embodiment, the back layer contains inorganic or organic particles. This further suppresses sticking and wrinkle formation caused by heating during heat transfer.

[0047] The thickness of the back layer is preferably 0.1 μm to 2 μm, and more preferably 0.1 μm to 1 μm. This allows for the suppression of sticking and wrinkle formation while maintaining the transferability of thermal energy during thermal transfer.

[0048] The back layer can be formed by dispersing or dissolving the above material in a suitable solvent to create a coating solution, applying it to the substrate using the above coating means to form a coating film, and then drying it.

[0049] <Method for manufacturing heat transfer sheets> The method for manufacturing a thermal transfer sheet in this disclosure is: A step of preparing a colorant layer forming coating liquid comprising a colorant, a resin component that forms urethane bonds by heating and hardens by ultraviolet irradiation, or an acrylic resin containing acryloyl groups and carboxyl groups that forms ester bonds by thermal curing, or a mixture of the above acrylic resin and a polyfunctional UV resin, The process includes the steps of applying the colorant layer forming coating liquid onto the substrate and drying it to form a coating film.

[0050] Specifically, first, the materials constituting the colorant layer are dispersed or dissolved in a suitable solvent to create a coating solution for forming the colorant layer. Next, this solution is applied to the substrate to form a coating film, which is then dried. This causes urethane bonding in the resin components, and the colorant layer is formed on the substrate by heat curing. Known methods such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating, or rod coating can be used as coating methods.

[0051] Furthermore, if the transfer layer includes a release layer, the release layer can be formed by dispersing or dissolving the constituent materials of the release layer in a suitable solvent to create a coating solution, applying it to the substrate using the above-mentioned coating means to form a coating film, and then drying it. Furthermore, if the transfer sheet includes a backing layer, the coating can be formed by dispersing or dissolving the constituent materials of the backing layer in a suitable solvent to create a coating solution, applying it to the substrate using the above-mentioned coating means to form a coating film, and then drying it.

[0052] <Manufacturing method for printed materials> The method for manufacturing a printed product disclosed herein is: The process of preparing the above-mentioned heat transfer sheet and the object to be transferred, A step of transferring the transfer layer provided by the heat transfer sheet onto the object to be transferred, The process includes irradiating the transfer layer transferred onto the object to be transferred with either ultraviolet light at a wavelength of 365 nm or ultraviolet light at a wavelength of 395 nm.

[0053] (Steps to prepare the heat transfer sheet and the object to be transferred) The method for manufacturing the heat transfer sheet is as described above, and will not be described here. The transfer target may be a resin film, a paper substrate, or other materials. Other thermal transfer receiving sheets may also be used.

[0054] (Transfer process of the transfer layer) The method for manufacturing a printed object according to this disclosure includes the step of transferring a transfer layer from a thermal transfer sheet onto a transfer surface. This allows an image to be formed on the transfer surface.

[0055] (Ultraviolet irradiation process) The method for manufacturing a printed product according to this disclosure includes a step of irradiating a transfer layer transferred onto a transfer substrate with ultraviolet light having a wavelength of 10 nm to 440 nm. In particular, it is preferable to irradiate with either ultraviolet light at a wavelength of 365 nm or ultraviolet light at a wavelength of 395 nm. This causes the acrylic groups in the resin component contained in the colorant layer of the transfer layer to react and harden, improving the solvent resistance and abrasion resistance of the printed product.

[0056] <Photographic prints> The prints of this disclosure are manufactured using the above-mentioned thermal transfer sheet and comprise a transfer surface and a transfer layer, the transfer layer comprising at least a colorant layer. In one embodiment, the transfer layer comprises a release layer on a colorant layer (not shown).

[0057] (Transferred object) The material to be transferred may be a resin film, a paper substrate, or the like. In one embodiment, a transfer subject having a metallic-looking transfer surface is used.

[0058] (Transfer layer) The transfer layer comprises at least a colorant layer. In one embodiment, the transfer layer comprises a release layer on the colorant layer.

[0059] (color material layer) The colorant layer contains a colorant and a UV-cured resin component. Aside from the fact that the colorant layer contains a colorant and an ultraviolet-cured resin component, its composition is the same as that of the colorant layer in a thermal transfer sheet, and is therefore omitted from this description.

[0060] (Exfoliation layer) The release layer has the same structure as the release layer of the thermal transfer sheet, so it will not be described here.

[0061] [1] A thermal transfer sheet comprising a substrate and a transfer layer, The transfer layer comprises a colorant layer, The aforementioned colorant layer is Colorants and, A resin component that forms urethane bonds upon heating and hardens upon ultraviolet irradiation. Or, An acrylic resin containing acryloyl groups and carboxyl groups, which forms ester bonds upon thermal curing, and A thermal transfer sheet wherein the ultraviolet transmittance of the transfer layer at a wavelength of 365 nm and the ultraviolet transmittance at a wavelength of 395 nm are 20% or more. [2] The heat transfer sheet according to [1], wherein the colorant is an azo pigment. [3] The heat transfer sheet according to [1] or [2], wherein the colorant is a red pigment or a blue pigment. [4] The heat transfer sheet according to any one of [1] to [3], wherein the resin component comprises an ultraviolet-curable resin. [5] The heat transfer sheet according to any one of [1] to [4], wherein the resin component comprises a polymer acrylate. [6] The thermal transfer sheet according to any one of [1] to [5], wherein the thickness of the transfer layer is 0.1 μm or more and 2.5 μm or less. [7] A method for manufacturing a thermal transfer sheet comprising a substrate and a transfer layer, A step of preparing a coating liquid for forming a colorant layer, which includes a colorant and a resin component that forms urethane bonds by heating and hardens by ultraviolet irradiation, or an acrylic resin containing acryloyl groups and carboxyl groups that forms ester bonds by thermal curing, A method for manufacturing a thermal transfer sheet, comprising the steps of applying the colorant layer forming coating liquid onto the substrate and drying to form a coating film. [8] A step of preparing a heat transfer sheet and a transfer object as described in any one of the items [1] to [6], A step of transferring the transfer layer provided by the heat transfer sheet onto the object to be transferred, A method for manufacturing a printed object, comprising the step of irradiating the transfer layer transferred onto the transfer object with ultraviolet light. [9] The method for manufacturing a printed object according to [8], using the transfer body having a metallic transfer surface. [Examples]

[0062] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0063] <Example 1> A release layer with the following composition was applied to one side of a 4.5 μm thick PET film and dried to form a 1 μm thick release layer. (Coating liquid for release layer) Carnauba wax 100 parts by mass ·Water 50 parts by mass • Isopropanol (IPA) 150 parts by mass

[0064] A colorant layer coating liquid 1 with the following composition was applied to the release layer and dried to form a colorant layer with a thickness of 1.0 μm. In the thermal transfer sheet of this embodiment, the transfer layer is composed of a release layer and a colorant layer. (Colorant layer coating liquid 1) ·Resin component 70 parts by mass (Manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A9300, ethoxylated isocyanuric acid triacrylate, polyfunctional) • Azo pigment A: 30 parts by mass (Manufactured by Dainichi Seika Kogyo, 8040 Red) ·Photopolymerization initiator 5% by mass (Manufactured by BASF Japan, Ilgacure® 819) ·MEK 50 parts by mass • Toluene 50 parts by mass

[0065] A back layer coating liquid with the following composition was applied to the side of the PET film opposite to the side on which the release layer was formed, and dried to form a back layer with a thickness of 0.3 μm, thereby obtaining a thermal transfer sheet. (Coating liquid for back layer) • Acrylic-modified silicone resin 10 parts by mass (Manufactured by Natco Corporation, Polyalloy NSA-X55) ·MEK 20 parts by mass

[0066] <Examples 2-8 and Comparative Example 1> A heat transfer sheet was prepared in the same manner as in Example 1, except that the composition and thickness of the colorant layer were changed as shown in Table 1. The details of each component in Table 1 are as follows: • Azo pigment B: Manufactured by Dainichi Seika Kogyo, Seika First Red 1547 • Azo pigment C: Manufactured by Dainichi Seika Kogyo, Seika First Carmine 1483-LT

[0067] <Ultraviolet transmittance measurement> (Preparing the blank) The thermal transfer sheets obtained in the examples and comparative examples, along with PET labels (Avery, 72825) as the transfer substrates, were prepared. The transfer layer of the thermal transfer sheet was transferred onto the material to be transferred using the test printer described below. This resulted in obtaining a thermal transfer sheet after the transfer layer had been transferred. (Test printer) • Thermal head: Kyocera Corporation, KEE-57-12GAN2-STA • Average resistance of heating element: 3303Ω • Main scanning resolution: 300 dpi (dots per inch) Sub-scanning direction resolution: 300dpi Printing voltage: 18V Line speed: 2.0 msec. / line ·Printing start temperature: 35℃ • Pulse duty cycle: 85% • Printed image: Solid black image (0 / 255 image gradation)

[0068] (UV transmittance measurement) A device was prepared consisting of a UV-Vis spectrophotometer (Shimadzu Corporation, UV-3100PC) with an integrating sphere attachment (Shimadzu Corporation, ISR-3100) attached. Thermal transfer sheets for the examples and comparative examples were prepared and placed on the sample beam side of a UV-Vis spectrophotometer. Next, the thermal transfer sheet after the transfer layer was transferred was placed as a blank on the control beam side, and the UV transmittance at wavelengths of 365 nm, 385 nm, and 395 nm was measured. The results are shown in Table 1.

[0069] <Creation of prints for evaluation> The thermal transfer sheets obtained in the examples and comparative examples, along with PET labels (Avery, 72825) as the transfer substrates, were prepared. The transfer layer of the thermal transfer sheet was transferred onto the object to be transferred using the test printer described above. The printed image was changed to a black and white barcode image.

[0070] After transfer, the transfer layer on the transfer substrate was irradiated with ultraviolet light under the following conditions to cure the transfer layer, and evaluation prints corresponding to the examples and comparative examples were prepared. Table 1 shows the thickness of the transfer layer on the material to be transferred. (Ultraviolet irradiation conditions) ·Ultraviolet irradiation device: TEXEL UV-015 • Total luminous intensity: 500 mJ / cm 2 , 1500 mJ / cm 2 • Light source: High-pressure mercury electrode lamp

[0071] <Solvent resistance evaluation> In accordance with JIS L 0849:2013, the surface of the evaluation print was rubbed with a cotton cloth impregnated with acetone using a JSPS-type friction durability tester (manufactured by Tester Industry Co., Ltd., AB-301) under the following conditions. (Rubbing conditions) • Load: 200g • Number of round trips: 100 • Amount of solvent used: 0.5cc

[0072] The remaining surface area of ​​the evaluation print after abrasion was observed visually and evaluated based on the evaluation criteria below. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: 90% or more ○: 80%~90% △: 70%~80% ×: Less than 70%

[0073] <Blocking resistance evaluation> Two test pieces measuring 5 cm x 5 cm were prepared from the heat transfer sheets obtained in the examples and comparative examples. These test pieces were stacked so that the transfer layer of one piece was in contact with the backing layer of the other piece, and stored in a 30°C oven for 24 hours under a load of 0.2 MPa. After storage, the test pieces were separated by hand and evaluated according to the evaluation criteria below. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: No adhesion was observed. ×: Adhesion was observed, making removal difficult.

[0074] <Evaluation of transcriptional cleavage> The remaining area of ​​the evaluation print after transfer was observed visually and evaluated based on the evaluation criteria below. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: 90% or more △: 80%~90% ×: Less than 80%

[0075] <Image Density Evaluation> The density (OD value) of the evaluation print after transfer was measured using a spectrometer (X-Rite i1Pro2) and evaluated based on the following evaluation criteria. (Measurement conditions) • Density Status: Status A • Measurement illumination conditions: M0 (ISO 13655-2009) (Evaluation Criteria) ○: 1.5 or higher △: 1.0 or higher, less than 1.5 ×: Less than 1.0

[0076] [Table 1]

Claims

1. A thermal transfer sheet comprising a base material and a transfer layer, The transfer layer comprises a colorant layer, The aforementioned colorant layer is Colorants and, A resin component that forms urethane bonds upon heating and hardens upon ultraviolet irradiation. Or, An acrylic resin containing acryloyl groups and carboxyl groups, which forms ester bonds upon thermal curing, and A thermal transfer sheet wherein the ultraviolet transmittance of the transfer layer at a wavelength of 365 nm and the ultraviolet transmittance at a wavelength of 395 nm are 20% or more.

2. The heat transfer sheet according to claim 1, wherein the colorant is an azo pigment.

3. The heat transfer sheet according to claim 1, wherein the colorant is a red pigment or a blue pigment.

4. The thermal transfer sheet according to claim 1, wherein the resin component includes an ultraviolet-curable resin.

5. The thermal transfer sheet according to claim 1, wherein the resin component includes a polymer-based acrylate.

6. The thermal transfer sheet according to claim 1, wherein the thickness of the transfer layer is 0.1 μm or more and 2.5 μm or less.

7. A method for manufacturing a thermal transfer sheet comprising a substrate and a transfer layer, A step of preparing a coating liquid for forming a colorant layer, which includes a colorant and a resin component that forms urethane bonds by heating and hardens by ultraviolet irradiation, or an acrylic resin containing acryloyl groups and carboxyl groups that forms ester bonds by thermal curing, A method for manufacturing a thermal transfer sheet, comprising the steps of applying the colorant layer forming coating liquid onto the substrate and drying to form a coating film.

8. A step of preparing a heat transfer sheet and a transfer object according to any one of claims 1 to 6, A step of transferring the transfer layer provided by the heat transfer sheet onto the object to be transferred, A method for manufacturing a printed object, comprising the step of irradiating the transfer layer transferred onto the transfer object with ultraviolet light.

9. A method for manufacturing a printed object according to claim 8, wherein the transfer subject has a metallic transfer surface.

Images