Transfer foil and authentication method

Abstract

We provide a transfer foil that allows for easy application of unique, individual authentication information to each foil. [Solution] The transfer foil comprises a support and a foil body to be joined to the object to be transferred. The foil body has a surface protection layer provided on the support, an optical forming layer provided on the surface protection layer, a reflective layer 23 made of metal provided on the optical forming layer, a mask layer 30 formed on the reflective layer, a cushion layer provided on the mask layer, and an adhesive layer provided on the cushion layer. The reflective layer has a plurality of pinholes 33 with a maximum dimension of 100 μm or less, and the area ratio of the pinholes to the area of ​​the reflective layer is 0.1% or more and 5% or less.

Description

Technical Field

[0001] The present invention relates to a transfer foil, and also refers to an authentication method using this transfer foil.

Background Art

[0002] As authentication bodies such as ID cards, vouchers, banknotes, passports, and driver's licenses, there are known ones in which a hologram transfer foil is hot-stamped for anti-counterfeiting purposes. In this hologram hot stamping, a heated die is used to thermally press the transfer foil onto the transfer object, and thus a transfer material layer that can be peeled off in the transfer foil is transferred onto the transfer object in the shape of the die to obtain a transfer.

[0003] As display bodies including personal information, various ID (Identification) cards such as passports and driver's licenses are known. Many ID cards display face images and character information for visual identification of personal information. If personal information is simply printed on the display body, it can be easily altered or forged.

[0004] As a method for preventing forgery of a display body, Patent Document 1 describes that by applying a hologram transfer foil to the display body, the anti-alteration property of the display body is improved. Patent Document 2 describes that by using a fluorescent material, personal information that is transparent and invisible in visible light observation and visible in ultraviolet light observation is imparted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The anti-counterfeiting technology described in Patent Document 1 is already widely known, and moreover, a simple hologram that emits iridescent diffracted light can be easily counterfeited.

[0007] Furthermore, while the anti-counterfeiting technologies described in Patent Document 1 and Patent Document 2 can display and represent fixed information, they have difficulty in creating individual authentication information that is different for each piece.

[0008] Based on the above circumstances, the objective is to provide a transfer foil that can easily be used to assign unique, individual authentication information to each item. [Means for solving the problem]

[0009] A first aspect of the present invention is a transfer foil comprising a support and a foil body to be bonded to a transfer object. The foil body comprises a surface protection layer provided on a support, an optical formation layer provided on the surface protection layer, a reflective layer made of metal provided on the optical formation layer, a mask layer formed on the reflective layer, a cushion layer provided on the mask layer, and an adhesive layer provided on the cushion layer. The reflective layer has multiple pinholes with a maximum size of 100 μm or less, and the area ratio of the pinholes to the area of ​​the reflective layer is between 0.1% and 5%.

[0010] A second aspect of the present invention is an authentication method using a transfer foil according to the first aspect. In this authentication method, the authenticity of a transfer with a foil body attached is determined based on the pattern of pinholes in the reflective layer. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a transfer foil to which unique individual authentication information can be easily assigned. [Brief explanation of the drawing]

[0012] [Figure 1]It is a cross-sectional view schematically showing a transfer foil according to an embodiment of the present invention. [Figure 2] It is a schematic diagram showing the configuration of a mask layer in the transfer foil. [Figure 3] It is a schematic diagram showing a reflective layer etched using the mask layer. [Figure 4] (a) to (c) are schematic diagrams showing the composition of the mask layer and the corresponding mode of the reflective layer. [Figure 5] It is a diagram showing an example of a foil body transferred to a transfer object. [Figure 6] It is a schematic diagram showing an example of the mode of a pinhole in the reflective layer of the foil body. [Figure 7] It is a schematic diagram showing an example of the mode of a pinhole in the reflective layer of the foil body. [Figure 8] It is an enlarged transmitted light image of a transfer foil according to a comparative example. [Figure 9] It is an enlarged transmitted light image of a transfer foil according to a comparative example. [Figure 10] It is an enlarged transmitted light image of a transfer foil according to an example. [Figure 11] It is an enlarged transmitted light image of a transfer foil according to an example. [Figure 12] It is an enlarged transmitted light image of a transfer foil according to an example. [Figure 13] It is an enlarged transmitted light image of a transfer foil according to an example. [Figure 14] ​​​​​​​​​​​​​​​​ The support 10 protects the functional layer 20 until the transfer foil 1 is transferred to the substrate. After the transfer foil 1 is heat-transferred to the substrate, such as a printed object, it is peeled off at the boundary with the functional layer 20. The support 10 is a base film or a coated base film. The base film can be a single-layer or multi-layer plastic film. The plastic film can be manufactured by extrusion, solution casting, or calendering. For extrusion, the inflation method or T-die method can be applied. The plastic film can also be stretched or unstretched. The material of the plastic film can be a thermoplastic resin or a soluble resin. For thermoplastic resins, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and PP (polypropylene) can be used. The base film can be a heat-resistant film or a pressure-resistant film. Heat-resistant and pressure-resistant materials can reduce deformation and deterioration due to heat and pressure applied during transfer. Depending on the application and purpose, the base film can be paper, synthetic paper, plastic multilayer paper, resin-impregnated paper, etc. The coated base film has one or both sides coated. This coating can be a resin alone or a resin containing powder. This coating can be microgravure coating, gravure coating, die coating, screen coating, etc. The resin used for coating can be acrylic resin, silicone resin, or fluororesin. The powder contained in the resin can be silica powder, silicone powder, fluororesin, or carbon powder. When the coating is on the functional layer 20 side, the retention and peeling of the functional layer 20 can be adjusted. When the coating is on the opposite side of the functional layer 20, blocking of the functional layer 20 with the adhesive layer 50 can be prevented, or the transport of the transfer foil can be made smoother, or both can be achieved. The thickness of the support 10 is preferably, for example, 4 μm or more. If the thickness is less than 4 μm, the physical strength as a support will be insufficient, making it difficult to handle the transfer foil. A more preferred thickness for the support 10 is 12 to 50 μm.

[0015] The functional layer 20 has a surface protection layer 21, an optical formation layer 22, a reflective layer 23, a mask layer 30, and a cushion layer 40, starting from the support 10 side. The basic structure of the functional layer 20 is known, but each layer is briefly described below.

[0016] The surface protection layer 21 supports the functional layer 20 to the extent that it can be peeled off from the support 10. After the transfer of the transfer foil 1, the surface protection layer 21 is exposed to the outermost surface, protecting the functional layer 20 from external damage. The surface protection layer 21 can be a layer containing a thermoplastic resin and a surface modifier. The thermoplastic resin of the surface protection layer 21 can be a resin with a glass transition temperature of 90°C or higher and 130°C. The thermoplastic resin can be any of acrylic resin, polyester resin, polyamide resin, polyethylene resin, norbornene resin, a copolymer resin of any of these, a composite resin of any of these copolymer resins, or a composite resin of any of these copolymer resins. Surface modifiers can be in the form of powders, waxes, or oils. The powder can be a heat-resistant powder. Heat-resistant powders can include silica powder, polyethylene powder, fluorine-based powder, or silicone-based powder. The wax can be paraffin wax, silicone wax, or carnauba wax. The oil can be silicone oil. The surface protection layer 21 may be colored. Coloring can be achieved by adding pigments or dyes to the resin of the surface protection layer 21. Pigments can be inorganic pigments, organic pigments, or mixtures of inorganic and organic pigments. Alternatively, pigments can be fluorescent pigments, pearl pigments, magnetic pigments, individual pigments, blends of the same type, mixtures of different types, or mixtures of the same type and different types. Dyes can be natural dyes, synthetic dyes, or mixtures of natural and synthetic dyes. Alternatively, the dyes can be fluorescent dyes. The surface protection layer 21 can be formed on the support 10 by printing or coating. Coating can be gravure coating, microgravure coating, or die coating. Printing can be gravure printing or screen printing. The thickness of the surface protection layer 21 is, for example, 0.5 μm to 5 μm. The surface protection layer 21 is printable. Acrylic resin is readily printable. A printable body with a transfer foil, having a surface protective layer 21 that can accept printing, can be printed as a single unit.

[0017] A wax layer may be provided between the support 10 and the surface protection layer 21. The wax layer can adjust the peelability of the surface protection layer 21 and improve the surface protection function. The type of wax used can be paraffin, hydrocarbon-based waxes such as polyethylene, carnauba-based waxes, or amide-based silicone waxes.

[0018] The optical formation layer 22 has a relief structure on at least one of its surfaces. The optical formation layer 22 can be formed from an ultraviolet-curable resin, a thermoplastic resin, or a thermosetting resin. The ultraviolet-curable resin can be a monomer, oligomer, or polymer having an ethylenically unsaturated bond or an ethylenically unsaturated group, which is a curing resin. Examples of monomers having an ethylenically unsaturated bond or an ethylenically unsaturated group include 1,6-hexanediol, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentalithritol hexaacrylate. Examples of oligomers having an ethylenically unsaturated bond or an ethylenically unsaturated group include an oligomer or co-oligomer of epoxy acrylate, urethane acrylate, or polyester acrylate. Examples of polymers include a polymer or copolymer of urethane-modified acrylic or epoxy-modified acrylic. The UV-curing resin can be any of the following: acrylic resin, acrylic acrylate resin, epoxy acrylate resin, urethane acrylate resin, polyester acrylate resin, or ethylene methacrylate resin; a copolymer of any of these; a composite resin of any of these; or a composite resin of any of these copolymers.

[0019] The optical forming layer 22 may be colored. The optical forming layer 22 can be colored by adding pigments or dyes to the resin of the optical forming layer 22. The pigments can be inorganic pigments or organic pigments. Alternatively, the pigments can be fluorescent pigments, pearl pigments, or magnetic pigments. The dyes can be natural dyes or synthetic pigments. Alternatively, the dyes can be fluorescent dyes. When a thermoplastic resin is used as the material for the optical forming layer 22, it can be any of acrylic resin, epoxy resin, cellulose resin, vinyl resin, copolymer resin of any of them, composite resin of any of them, or composite resin of any of them. The thermosetting resin for the optical forming layer 22 can be any of urethane resin, melamine resin, epoxy resin, phenolic resin, copolymer resin of any of them, composite resin of any of them, or composite resin of any of them.

[0020] The relief structure of the optical formation layer 22 is composed of fine irregularities and has optical effects such as optical diffraction, anti-reflection, isotropic or anisotropic scattering, lensing, and polarization-selective reflection, which can be detected by visual inspection or mechanical detection to prevent counterfeiting and improve design aesthetics. The optical effects can be selected by combining one or more reliefs having different optical effects. The relief structure on the surface of the optically formed layer 22 has recesses or protrusions, or both recesses and protrusions, and provides the functional layer 20 with optical properties such as diffraction, light reflection suppression, isotropic or anisotropic light scattering, refraction, polarization / wavelength selective reflection, transmission, and light reflection suppression. By providing regions of diffraction grating structures in the optically formed layer 22 with a pitch of, for example, 0.5 μm to 2 μm and a depth of 0.05 μm to 0.5 μm, the relief structure imparts the property of diffracting light to the functional layer 20. By providing moth-eye structures or deep grating structures in the optically formed layer 22 with a pitch of, for example, 0.1 μm to 0.5 μm and a depth of 0.25 μm to 0.75 μm, the relief structure imparts light reflection suppression properties, polarization / wavelength selective reflection, transmission, and light reflection suppression to the functional layer 20. By providing the relief structure with regions of a non-periodic linear or dot-like repeating structure, for example, with an average pitch of 0.5 μm to 3 μm and a depth of 0.05 μm to 0.5 μm, the relief structure imparts the property of emitting isotropic or anisotropic scattered light to the functional layer 20. By providing the optical formation layer 22 with regions of structure with an average pitch greater than 3 μm and a depth greater than 0.5 μm, and by giving it a different refractive index from adjacent layers, the relief structure imparts the property of refraction to the functional layer 20. The optical properties of the functional layer 20 can be perceived and detected by visual inspection or mechanical detection. This can improve the performance of preventing counterfeiting and tampering, as well as the design aesthetics. The relief structure on the surface of the optical formation layer 22 may have multiple relief structure regions. The relief structure regions can display images individually or as a combination of multiple regions. The images can be individual pictures, photographs, portraits, landmarks, marks, or logos, or combinations thereof.

[0021] The reflective layer 23 is formed on part or all of the optical formation layer 22. When the reflective layer 23 is formed on part of the optical formation layer 22, the manufacturing of the functional layer 20 requires advanced processing technology, resulting in a more refined design, and thus the transfer foil 1 can have a higher anti-counterfeiting effect. The reflective layer 23 allows for easy observation of the optical properties produced in the optically formed layer 22. The reflective layer 23 may display structural colors. Structural colors include color-changing colors, iridescent colors, etc. As the material for the reflective layer 23, elemental metals or silicon, alloys, or compounds thereof can be used. The metals or silicon constituting the elements, alloys, or compounds thereof can be any or a combination of Si, Al, Sn, Cr, Ni, Cu, Ag. The thickness of the reflective layer 23 can be in the range of 10 to 500 nm. The reflective layer 23 can be formed by depositing inorganic material under reduced pressure. This can be done by physical deposition or chemical deposition (CVD). The reflective layer 23 can be formed by vacuum deposition or sputtering in physical deposition. Alternatively, the reflective layer 23 may be formed by chemical deposition (CVD). Vacuum deposition is easier to reduce costs. The reflective layer 23 can be single-layer or multi-layer. A single-layer reflective layer can be made by depositing aluminum or an aluminum alloy. In this case, the thickness can be in the range of 35 to 80 nm. If it is less than 35 nm, the reflectivity of visible light will be low and it may not be possible to obtain an optical effect due to reflection. If it exceeds 80 nm, etching will take a long time and productivity may decrease. A multi-layer reflective layer 23 can be made by alternately stacking elemental metals and metal compounds, by alternately stacking elemental metals of different types, or by alternately stacking metal compounds of different types. As an example of alternately stacking elemental metals and metal compounds, a multi-layer can be made by stacking a silicon dioxide deposition layer on an aluminum layer. The reflective layer 23 may be a single layer of metal deposited on a single layer of metal compound. In this case, the metal compound can be titanium oxide or zinc sulfide. The metal layer can be aluminum or an aluminum alloy. In this case, the thickness of each can be in the range of 20 to 100 nm, with 40 to 80 nm being optimal.

[0022] The mask layer 30 functions as a protective layer for the underlying layer. The mask layer 30 has a thickness of, for example, 0.8 to 1.5 μm and can be patterned by printing. If the mask layer 30 is partially formed by printing, the reflective layer 23 can also be demetallized by etching to remove the areas where the mask layer 30 is not present. This allows the reflective layer 23 to pattern its contour. The contour pattern of the reflective layer 23 can be easily detected by a camera, and this contour pattern can be used to form alignment marks that detect distortion during camera photography, to form position detection patterns, or to record one-dimensional or two-dimensional codes. The one-dimensional code can be a string of characters or a barcode. The two-dimensional code can be a QR code (registered trademark). These codes may also be ciphertext. The ciphertext may be ciphertext in which individual information has been encrypted. Furthermore, ciphertext obtained by encrypting the hash value between the code recorded in the contour pattern and the individual information can also be recorded as further encrypted information. If the thickness of the mask layer 30 is 0.8 μm or less, the reflective layer 23 may be excessively etched, making patterning difficult. If the thickness is 1.5 μm or more, the reflective layer 23 becomes difficult to etch, requiring heating conditions, which may cause deformation of other layers or the support. Therefore, from the viewpoint of etching control, the thickness of the mask layer is preferably in the range of 0.8 to 1.5 μm.

[0023] The material of the mask layer 30 can be a resin, an inorganic material, or a composite of a resin and an inorganic material. The mask layer 30 contains at least a vinyl chloride / vinyl acetate copolymer and a polycarbonate resin, but it can also be a composite resin containing a curing resin to improve resistance. The curing resin can be a thermosetting resin such as a urethane resin or an epoxy resin. By including a curing resin, the mask layer 30 is more likely to obtain etching resistance. The other resins contained in the mask layer 30 may be any of the following: vinyl resin, polystyrene resin, acrylic resin, polyurethane resin, polyamide resin, polyimide resin, copolymer resin of any of these, composite resin of any of these, or composite resin of any of these copolymer resins. The vinyl resin may be vinyl chloride, polyvinylidene chloride, or polyvinyl alcohol. The polystyrene resin may include polystyrene-based polystyrene, styrene-acrylonitrile copolymer, polyethylene, or ethylene vinyl acetate copolymer. The acrylic resin may be polymethyl methacrylate. Furthermore, the resin may be a copolymer of at least two of these. In addition, the molecules of the above resins may contain ester bonds, urethane bonds, ether bonds, amine bonds, silanol bonds, etc. The chemical structures of two or more resins having functional groups involved in these bonds may be crosslinked. The mask layer 30 may contain other additives to improve printability, chemical resistance, and heat resistance. Examples of additives include waxes such as polyethylene wax, carnauba wax, and microcrystalline wax, as well as inorganic fillers such as silica and barium sulfate, and resin fillers such as acrylic resin.

[0024] As will be described in detail later, in this embodiment, it is important that the mask layer 30 forms a sea-island structure due to the phase separation of the resin, so it is preferable to include at least two types of resins with poor compatibility. Since the main chain structure of the resin greatly affects compatibility, it can be easily inferred that a resin with saturated bonds in the main chain and a resin with a cyclic structure in the main chain have poor compatibility. Among these, a combination of an amorphous resin, elastomer, which has saturated bonds in its main chain, and an aromatic resin, which has a cyclic structure of benzene rings in its main chain, is particularly good. Furthermore, among these, a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin is excellent. Vinyl chloride / vinyl acetate copolymer has good adhesion to inorganic materials and other resins, making it suitable for mask materials. However, it is inferior in heat resistance and chemical resistance, so by using polycarbonate resin, it is possible to provide a mask layer 30 suitable for individual certification while maintaining both resistance and chemical resistance. Other elastomers such as polybutylene terephthalate (PBT) and methyl methacrylate (PMMA) can also be used, but vinyl chloride / vinyl acetate copolymer is superior in terms of adhesion, chemical resistance, availability, cost, and coating suitability. The Tg (glass transition point) of the vinyl chloride / vinyl acetate copolymer is preferably 90°C or lower, and the Tg of the polycarbonate is preferably 120°C or higher. If a vinyl chloride / vinyl acetate copolymer with a Tg exceeding 90°C is used, the adhesion between the mask layer 30 and the reflective layer 23 and cushion layer 40 will decrease. On the other hand, if polycarbonate with a Tg below 120°C is used, the heat resistance and chemical resistance will decrease. Therefore, it is preferable that the vinyl chloride / vinyl acetate copolymer and polycarbonate satisfy the above Tg requirements.

[0025] The cushion layer 40 is formed as needed between the reflective layer 23 or mask layer 30 and the adhesive layer 50 to enhance interlayer adhesion. It also works in conjunction with the adhesive layer 50 to provide robustness to the transfer foil 1, which is useful when the object to which the transfer foil 1 is transferred is permeable to liquids.

[0026] The cushion layer 40 is laminated to absorb pressure during application or as an anchor layer to ensure adhesion between the reflective layer 23 and the adhesive layer 50. The cushion layer 40 can be a matrix containing soft resins of different flexibility and deformation limiting agents to absorb pressure. The matrix can be a polymer or copolymer of any of the following: vinyl chloride, vinyl, cellulose, phenol, fluorine-based, silicone-based, acrylic-based, melamine-based, epoxy-based, or ester-based.

[0027] The soft resin of the matrix of the cushion layer 40 is preferably one that has good adhesion to the vinyl chloride / vinyl acetate copolymer of the mask layer 30, and an acid-modified polyolefin resin is a suitable example. Acid-modified polyolefin resins may also be copolymer resins of ethylene and an acidic component. Copolymers of ethylene and an acidic component can be ethylene (meth)acrylic acid copolymer resin (EMAA), ethylene-vinyl acetate copolymer resin, or ethylene (meth)acrylic acid ester copolymer resin. Copolymer resins of ethylene and an acidic component tend to have moderate flexibility and good adhesion to adjacent layers. The soft resin in the cushion layer 40 can have a softening temperature lower than that of the vinyl chloride / vinyl acetate copolymer in the cushion layer 40, and furthermore, a softening temperature lower than the transfer temperature during hot stamping. The softening temperature of the resin in the cushion layer 40 can be in the range of 60°C to 110°C. The transfer temperature is the hot stamping plate surface temperature of the hot stamping foil, and can be in the range of 90°C to 130°C. This softening temperature is well compatible with the hot stamping plate surface temperature of the hot stamping foil, which is in the range of 90°C to 130°C. The transfer temperature is typically 120°C. The acid value of acid-modified polyolefins can be measured using commonly used methods such as FT-IR or titration. The acid value of acid-modified polyolefins can range from 0.5 to 200.

[0028] A dispersion, which is a dispersion of the soft resin, may be used as the coating liquid containing the soft resin used to prepare the cushion layer 40. In this case, the size of the soft resin particles contained in the dispersion can be about 30 μm.

[0029] Additives may be added to the cushion layer 40. The amount of additive can be in the range of 0.1 Wt% to 10 Wt% relative to the matrix. Silane coupling agents and isocyanates may be added as additives. By adding a silane coupling agent, even when a portion of the cushion layer 40 is in contact with the reflective layer 23, the stability of adhesion with the mask layer 30, etc., is improved by the formation of silanol bonds. The silanol bonds also improve the heat resistance and solvent resistance of the cushion layer 40. Furthermore, when a portion of the cushion layer 40 is in contact with the optical forming layer 22, the adhesion with the silane compound added to the optical forming layer 22 that is present on the surface of the optical forming layer 22 is also improved.

[0030] If the cushion layer 40 contains isocyanate, urethane bonds are formed in the portion of the cushion layer 40 that is in contact with the optical forming layer 22, improving adhesion, heat resistance, and solvent resistance. The matrix of the cushion layer 40 may also be fluorescent. Fluorescence can be achieved by the resin or polymer having a fluorescent molecular structure, by adding a fluorescent agent to the resin, or by the resin or polymer having a fluorescent molecular structure and adding a fluorescent agent to the resin. The thickness of the cushion layer 40 can be in the range of 0.5 μm or more and 3 μm or less.

[0031] The cushion layer 40 can also be made of a crystalline polyester resin with a melting point of 80-120°C. The cushion layer 40 is laminated on the mask layer 30, and the side opposite to the mask layer 30 is in contact with the adhesive layer 50. From the viewpoint of adhesion to the laminated layer, polyester is optimal for the cushion layer 40, and furthermore, crystalline polyester is preferred from the viewpoint of thermal properties (having a melting point) and solvent resistance. Because crystalline polyester has a melting point, there is a difference in the state of the resin when it is molten and when it is non-molten. Here, the melting point of crystalline polyester is influenced by the crystal structure and molecular structure. For example, even with the same molecular weight (Mn25000), some have a melting point of 198°C while others have a melting point of 125°C. When the transfer foil 1 is stored, if the melting point of the polyester resin in the cushion layer 40 is 60°C or lower, it will melt at the blocking storage temperature of 60°C, causing blocking. The melting point of the cushion layer 40 can be measured, for example, by exposing the cross-section of the transfer foil 1 while it is in its original state, using a nanoindenter.

[0032] The cushion layer 40 may contain fillers with a particle size smaller than the thickness of the cushion layer 40 in order to improve cutability. Specifically, these can be inorganic materials, heat-resistant resins, composites of inorganic materials and heat-resistant resins, or natural materials. Inorganic materials can be inorganic compounds or pure substances. Inorganic compounds can be silica, calcium carbonate, talc, barium sulfate, mica, aluminum hydroxide, magnesium hydroxide, kaolin clay, zeolite, mica, etc. Pure substances can be carbon black.

[0033] Crystalline polyester can be applied in both a dissolved ink state and a dispersion state dispersed in a solvent. The cushion layer 40 can be formed by coating or printing. Coating can be roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating, rod coating, lip coating, die coating, etc. Printing may also be applied to coating. Printing can be gravure or screen printing. Drying of the coating liquid is preferably carried out at a temperature below the melting point of the solids.

[0034] The cushion layer 40, made of a crystalline polyester resin with a melting point of 80-120°C, can achieve both blocking resistance and adhesion by adjusting the amount of elastic deformation of the adhesive layer 50 according to the melting point characteristics of the polyester resin at different temperatures. Specifically, when the transfer foil 1 is stored in a roll, the storage temperature is 60°C, so the cushion layer 40 does not melt and has no fluidity, and the adhesive layer 50 is also hard at 60°C due to its high storage modulus. Therefore, a gap is maintained between the adhesive layer 50 and the support 10 that overlaps it. On the other hand, during thermal transfer at a transfer temperature of 90-120°C, the cushion layer 40 melts and becomes fluid, and the elastic deformation rate of the adhesive layer 50 increases. As a result, the cushion layer 40 comes into contact with the adhesive layer 50, and the adhesive layer 50 becomes more easily deformed, making it easier to adhere to the object to be transferred.

[0035] The adhesive layer 50 firmly adheres to the object to be transferred, and at the same time, if the object to be transferred is permeable to liquids, it provides robustness.

[0036] The adhesive layer 50 has a thermoplastic resin matrix in which spacer particles are dispersed. The matrix of the adhesive layer 50 may also contain inorganic powder filler. The ratio of inorganic powder filler to the thermoplastic resin matrix can be in the range of 0.1% or more and 100% or less. Various well-known adhesives and sealants can be used as the thermoplastic resin for the matrix. The thermoplastic resin can be acrylic resin. The acrylic resin can be polymethyl methacrylate. When transfer foil 1 is applied to security printing, if acrylic resin is used as the thermoplastic resin for the matrix of the adhesive layer 50, transfer becomes possible with less heat, and transfer can be performed with short periods of heat and pressure during the transfer process. This improves the transfer throughput. In this disclosure, "short-time heat pressurization" generally refers to heat pressurization for less than 1 second at a plate surface temperature of 90 to 130°C. Therefore, the thermoplastic resin used in the adhesive layer 50 is not limited to acrylic resin, but can also be other thermoplastic resins with a melting point between 60°C and 130°C. In this case, transfer can be performed with even shorter heat pressurization times.

[0037] The resin other than the acrylic resin used in the matrix of the adhesive layer 50 can be any of the following: vinyl resin, polystyrene resin, polyurethane resin, or a mixture of any of these with acrylic resin. The vinyl resin can be vinyl chloride, polyvinylidene chloride, or polyvinyl alcohol. The polystyrene resin can be polystyrene, styrene-acrylonitrile copolymer, polyethylene, or ethylene vinyl acetate copolymer. Alternatively, a resin obtained by copolymerizing two or more of these may also be used. The above resins may contain ester bonds, urethane bonds, ether bonds, amine bonds, and silanol bonds, and the chemical structures of two or more resins having functional groups involved in these bonds may be crosslinked. These bonds allow for adjustment of molecular weight, and thus control of softening temperature, viscoelasticity, and solvent resistance. Furthermore, these resins may be copolymerized or modified. The matrix of the adhesive layer 50 may be fluorescent. Fluorescence can be achieved by the resin or polymer having a fluorescent molecular structure, by adding a fluorescent agent to the resin, or by the resin or polymer having a fluorescent molecular structure and adding a fluorescent agent to the resin. The thickness of the adhesive layer 50, as defined by the matrix, is preferably greater than the arithmetic mean roughness Ra of the object to be transferred, and is generally in the range of 2 μm or more and 10 μm or less.

[0038] The spacer particles have an average particle size greater than the thickness of the adhesive layer 50. Furthermore, the average particle size of the spacer particles can be greater than the total thickness (the sum of the adhesive layer 50 and the cushion layer 40), and no more than twice the total thickness. The average particle diameter of the spacer particles can be in the range of 1 μm to 10 μm. The average particle diameter of the contained particles can be measured using a laser diffraction / scattering particle size distribution analyzer (such as Microtrac BlueRaytrac, manufactured by Microtrac-Bell Corporation), and represents the volume-average particle diameter. Spacer particles can be a blend of two groups of particles with different average particle sizes. In this case, the average particle size of the relatively smaller group of particles in the spacer particles may be in the range of 1 to 10 μm, and the average particle size of the relatively larger group of particles may be in the range of 10 μm to 30 μm. When blending two groups of particles with different average particle sizes, the volume ratio of the larger group of particles can be greater than that of the smaller group. The volume ratio of the larger group to the smaller group of particles can be 1:50 or more and 1:2 or less. Furthermore, spacer particles can be a blend of two or more groups of particles with different average particle sizes. Spacer particles can be either shaped or amorphous. Shaped particles can be elliptical or spherical. Shaped particles are more likely to maintain a stable gap. Elliptical particles are robust to pressure. Spherical particles provide a consistent response to pressure. Amorphous particles can reduce costs. It is preferable to use monodisperse particles where the particle size is uniform. Monodisperse generally means that the CV value = (standard deviation / mean) is 10% or less. Spacer particles can be inorganic, heat-resistant resin, or a composite of inorganic and heat-resistant resin. Inorganic materials can be inorganic compounds or pure substances. Inorganic compounds can be silica, calcium carbonate, talc, barium sulfate, mica, aluminum hydroxide, magnesium hydroxide, or kaolin clay. Pure substances can be carbon black. The heat-resistant resin used as the material for the spacer particles can be synthetic resin or natural material. Synthetic resins can be acrylic resin, urethane resin, polyethylene resin, or polypropylene resin. Natural materials can be wood powder or amber. Furthermore, the inorganic and heat-resistant resin composite of spacer particles 41 can be made from the materials listed above, either inorganic or heat-resistant resin. Inorganic materials easily provide heat resistance and chemical resistance. Synthetic resins easily provide heat resistance and chemical resistance. Natural materials have a low environmental impact. The volume ratio of spacer particles to the matrix of the adhesive layer 50 can be in the range of 0.1% or more and 3% or less.

[0039] The adhesive layer 50 can be formed by applying a coating solution containing a matrix thermoplastic resin and spacer particles. The coating solution may be one in which the solid components are completely dissolved, or it may be one in which the solid components are dispersed, such as a dispersion or emulsion. The coating can be a roll coat, reverse roll coat, gravure coat, reverse gravure coat, bar coat, rod coat, lip coat, or die coat. Printing may also be applied to the coating. The printing can be gravure or screen printing. It is preferable to dry the coating solution at a temperature below the melting point of the solid components.

[0040] The transfer foil 1 of this embodiment, having the above configuration, contains a mask layer 30 containing two types of resins with poor compatibility. As a result, the mask layer 30 has a sea-island structure including a continuous layer 31 and a dispersion layer 32, as shown in Figure 2. This sea-island structure does not significantly impair the flatness of the mask layer 30, unlike mixing in fillers, but an interface is formed at the boundary between the continuous layer 31 and the dispersion layer 32. Depending on the configuration of the dispersion layer 32, this interface may extend over the thickness direction of the mask layer 30, and the gap between the interfaces may also penetrate the mask layer 30 in the thickness direction. In the demetallization process described above, the portion of the reflective layer 23 covered by the mask layer 30 is not normally etched, but the etching solution passes through the gaps that penetrate in the thickness direction as described above and dissolves the reflective layer. As a result, minute pinholes 33 are formed in the portion of the reflective layer 23 covered by the mask layer 30, as shown in Figure 3. Because these pinholes 33 are minute, they do not adversely affect the appearance of the transfer foil 1 itself or the visual effects such as holograms.

[0041] The dispersion layer 32 in the mask layer 30 differs depending on the transfer foil 1 and cannot be controlled. Therefore, the number, position, and dimensions of the pinholes 33 that occur in the reflective layer 23 differ for each transfer foil and are almost never identical. Consequently, the characteristics of the pinholes 33 in the transfer foil 1 can be used as information to identify individual transfer foils.

[0042] As mentioned above, pinholes 33 generally do not negatively affect the appearance of the transfer foil 1 itself or the visual effects such as holograms. However, if their size becomes excessively large or their number becomes excessively large, they may impair the appearance and visual effects. This can be suppressed to some extent by the composition of the mask layer 30, and this point will be explained below.

[0043] If the area ratio of pinholes 33 to the area of ​​the reflective layer 23 is too small, it becomes difficult to use for authentication, and if it is too large, there are concerns about the impact on appearance and visual effect. From this perspective, it is preferable that the area ratio of pinholes 33 in the reflective layer 23 be between 0.1% and 5%. Figure 4 shows a schematic diagram illustrating the relationship between the composition of a mask layer 30, consisting of poorly compatible resins A and B, and the characteristics of pinholes. In (a), the ratio of resin A to resin B is 70:30; in (b), the ratio of resin A to resin B is 50:50; and in (c), the ratio of resin A to resin B is 30:70. Note that the continuous layer 31 is composed of a relatively larger amount of resin, so in (a) and (c), the resins constituting the continuous layer 31 and the dispersed layer 32 are reversed, and in (b), the resin forming the continuous layer 31 differs depending on the area being observed. As the difference between the amount of resin A and the amount of resin B decreases, the number of interfaces increases, and therefore the number of pinholes 33 that occur also tends to increase. Therefore, theoretically, the area ratio of pinholes is likely to be maximum when the ratio of resin A to resin B is 50:50. If the area ratio of pinholes 33 under the condition of a 50:50 ratio is within the above range, the mixing ratio of resin A and resin B should be determined by considering only the lower limit of the above range. On the other hand, if the area ratio under the condition of a 50:50 ratio exceeds the upper limit of the above range, the mixing ratio of resin A and resin B should be determined by considering both the lower and upper limits. As will be shown later in the examples, the inventors' studies have confirmed that in a mask layer made of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, the area ratio of pinholes can be kept within the above range by setting the ratio of the two materials in the range of 10:90 to 90:10.

[0044] The dimensions of the pinhole 33 relative to the area of ​​the reflective layer 23 affect the visibility to the user, specifically whether or not it can be seen with the naked eye. Since the resolution of the human eye is approximately 100 μm, from this viewpoint, it is preferable that the maximum dimensions of the pinhole 33 be 100 μm or less. As most of the formed pinholes 33 have a shape that can be approximated as an ellipse, the major axis is defined as the maximum dimension of the pinhole, among the minor axis diameter (short axis) and major axis diameter (long axis), which are generally used as a standard for particle length. The major axis is defined as the distance at which the distance between two parallel lines is shortest when the outline of the pinhole on the image is enclosed by two parallel lines tangent to it, and the major axis is the maximum dimension in the direction perpendicular to the line segment indicating the minor axis. The maximum size of the pinhole 33 depends on the ratio of the resin A and resin B that make up the mask layer 30, specifically the resin with lower resistance to the etching solution used. The resin with lower resistance to the etching solution dissolves during etching, which widens gaps at the interface and creates through-holes even in areas without interfaces, thereby increasing the maximum size of the pinhole 33. In a mask layer made of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, the polycarbonate resin has lower resistance to the etching solution, so the maximum size of the pinhole 33 tends to increase as the ratio of polycarbonate resin increases. The inventors' studies have confirmed that when the ratio of polycarbonate resin is 50% or less, the maximum size of the pinhole 33 is about 20-40 μm, but when the ratio of polycarbonate resin exceeds 50%, the maximum size begins to increase, and when it exceeds 70%, the maximum size tends to exceed 100 μm.

[0045] Based on the two points mentioned above, in a mask layer consisting of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, the solid content ratio of polycarbonate resin to vinyl chloride / vinyl acetate copolymer is preferably 10:90 to 70:30. Such a mask layer can be realized by setting the solid content ratio of polycarbonate resin to vinyl chloride / vinyl acetate copolymer in the coating liquid used to form the mask layer to 10:90 to 70:30.

[0046] The sea-island structure of the mask layer 30 can be visualized by immersing it in a chemical solution that dissolves the reflective layer 23, such as alkali, even after the transfer foil 1 is completed or when the transfer foil 1 has been transferred to the object to be transferred, and can be easily observed with an optical microscope or laser microscope.

[0047] The sea-island structure of the exposed mask layer 30 can be clearly identified by coloring. In the case of a mask layer consisting of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, cyan from photographic sublimation film is superimposed on the transfer foil or transfer material with the mask layer exposed, and transferred under conditions such as those described below. In this case, the vinyl chloride / vinyl acetate copolymer portion is colored, while the polycarbonate resin portion is not colored, so the continuous phase and dispersed phase can be clearly identified. • Transfer device: Up / down type hot stamping machine (Navitas Machinery MP-10BX) ·Set temperature: 120℃ • Pressure: 3.5t • Duration: 1 second

[0048] Next, an example of an authentication method using the transfer foil 1 will be described. The transfer foil 1 is bonded to the object to be transferred by bringing the adhesive layer 50 into contact with the object to be transferred and applying heat and pressure. After that, the support 10 is peeled off and the remaining part including the functional layer 20 (hereinafter sometimes referred to as the "foil") remains on the object to be transferred, becoming the transfer object. In the foil 60 on the transfer object shown in Figure 5, a part of the reflective layer 23 has been removed by demetallization, and a design portion Z of a predetermined shape has been formed. Of the foil 60, the surface protective layer 21 and the optical forming layer 22 located on the reflective layer 23 are transparent, so the reflective layer 23 surrounding the design portion Z can be seen through these layers in a plan view of the foil 60. As described above, pinholes are formed in the reflective layer 23 of this embodiment in different ways.

[0049] First, a predetermined position and range of the reflective layer 23 is set as a designated area K for use in detecting feature information. This location is the same for all foil bodies 60. Figure 5 shows an example where there is one designated area K, but multiple designated areas K may be provided.

[0050] Figures 6 and 7 are enlarged schematic diagrams of designated areas K in different foil bodies 60. In Figure 6, a pinhole p1 is located in the upper left part of the designated area K, a pinhole p2 in the lower left part, and a pinhole p3 in the lower right part, with no pinholes in the lower right part. Note that the shapes of pinholes p1 to p3 in the figures are to show that the three pinholes have different shapes, and do not represent their actual shapes. Similarly, in Figure 7, a pinhole p4 is located in the upper left part of the designated region K, a pinhole p5 in the upper right part, a pinhole p6 in the lower left part, and a pinhole p7 in the lower right part.

[0051] The pinhole configuration within such a designated region K can be coded in various ways. For example, if the first digit is the total number of pinholes within the designated area K, and the second to fifth digits are assigned the number of pinholes in each of the four sections into which the designated area K is divided, in the order of upper left, upper right, lower left, and lower right, then the code corresponding to the configuration in Figure 6 will be "31011", and the code corresponding to the configuration in Figure 7 will be "41111". This code serves as individual identification information for each foil body 60 or each transfer foil 1 before transfer. If the number of pinholes is 10 or more, letters may be used in the code, for example, "G10C4".

[0052] The above is an extremely simple example, and as the number of foil bodies 60 or transfer foils 1 increases, the likelihood of multiple individuals with the same code increases, but for example, • Area ratio of pinholes (the entire specified region K, each part, or both) • Maximum dimensions of the pinhole (the entire specified area K, each part of it, or both) By appropriately combining other information to complicate the code, the possibility of multiple individuals having the same code can be reduced, and it is not difficult to make it virtually zero. Furthermore, when authentication is performed in combination with a serial number, as described later, the existence of multiple individuals with the same code does not pose a practical problem. These pinholes can be easily identified by transmission observation. Specifically, they can be identified by illuminating one side of the transfer foil with diffused light and observing the transmitted light with a camera. The transmitted light can be visible light or infrared light. The camera can consist of an image sensor and a lens. The image sensor can be made of silicon, gallium, or gallium silicon. This sensor can have a CCD or CMOS structure. The lens may be a macro lens. Imaging with a macro lens makes it easy to image minute pinholes that are invisible to the naked eye. Because these pinholes are generated accidentally during manufacturing, it is virtually impossible to intentionally produce identical items, thus providing extremely high anti-counterfeiting capabilities. For this reason, it can be applied to items that are rare, traded at extremely high prices, and where sophisticated counterfeiting is anticipated. On the other hand, the manufacturing of the transfer foil itself can be done at low cost, and authentication can be done using a smartphone with a dedicated app installed, a macro lens attached, and a tracing light as the light source, so there is no need to popularize dedicated authentication devices, making it highly convenient.

[0053] Here is an example of an authentication method. For instance, if the transfer is a banknote, a code corresponding to the attached foil, along with the serial number, is printed on the transfer. To authenticate whether a banknote is genuine, the pattern of the pinholes is obtained by acquiring magnified images of the reflective layer of the bonded foil, and then compared with the printed code. If the pattern of the pinholes matches the printed code, the banknote is determined to be genuine; if they do not match, it is determined to be counterfeit.

[0054] When a malicious third party counterfeits banknotes, the same serial number and code as the original banknote are printed on them, and the foil body related to the counterfeit transfer foil is joined to it. However, if the mask layer does not have a sea-island structure, the reflective layer of this foil body will not have pinholes, and even if it does have a sea-island structure, the pattern of the pinholes will be different from the foil body joined to the original banknote. In either case, it is practically impossible for the pattern of the pinholes in the acquired magnified observation image to match the printed code. Thus, the authentication method according to this embodiment can reliably identify counterfeit products by using the transfer foil 1 and foil body 60 according to this embodiment.

[0055] The authentication method according to this embodiment is not limited to the above-described configuration. For example, instead of printing the code on the transfer section, the code or information about the pinhole before coding may be stored in a database in the form of a table or the like, and the determination may be made by comparing the pinhole configuration obtained from the magnified observation image with the database. Furthermore, when printing codes on a transcription, instead of printing them directly, you may print them after encrypting them with a predetermined key.

[0056] Furthermore, authentication is possible even without combining serial numbers, simply by checking whether there is a match between the pinhole pattern obtained from the magnified observation image and a database of issued transfer foils. As mentioned above, the probability that the pinhole pattern of a transfer foil forged by a malicious third party will coincidentally match one of the issued transfer foils is extremely low, and can be considered almost zero.

[0057] The transfer foil according to this embodiment will be further described using examples and comparative examples. The technical scope of the present invention is not limited solely on the basis of the specific contents of these examples.

[0058] (Example 1) A wax layer was formed on one side of the support by applying and drying an ink for forming a wax layer so that the dry film thickness (dry film thickness) was 0.2 to 0.7 μm. Furthermore, an ink A, described later, was applied and dried so that the dry film thickness was 1 μm to form a surface protective layer. Next, ink B, described later, was applied to the surface protective layer and dried to a dry film thickness of 1 μm. Then, a micro-relief pattern constituting a diffraction grating was formed using a roll embossing method, thereby forming an optical formation layer. Next, a reflective layer was formed on the optical formation layer by vacuum deposition of aluminum to a thickness of 50 nm. Next, ink C1, described later, was applied to the reflective layer and dried to a dry film thickness of 1 to 1.5 μm to form a mask layer. Based on the above, a functional layer was formed on the support. Subsequently, ink D, described later, was applied to the functional layer and dried to a dry film thickness of 1-2 μm to form a cushion layer. Finally, ink E, described later, was applied to the cushion layer and dried to form an adhesive layer, with a dry film thickness of the resin component reaching 4-5 μm. Based on the above, the transfer foil according to Example 1 was prepared.

[0059] Details of the materials used in Example 1 are shown below. In the following description, "parts" means parts by mass unless otherwise specified. ·Support PET film (38μm thickness) (Toray Lumirror) • Ink A (for surface protective layer) Toluene 43.0 parts Methyl ethyl ketone 43.0 parts Acrylic resin (Mitsubishi Rayon Byron BR80) 6.0 parts Acrylic resin (Mitsubishi Rayon Byron BR83) 6.0 parts Polyethylene wax (Koyo Chemical CE155 NV15) 1.0 part Polyester resin (Elite UE3320) 1.0 part • Ink B (for optical formation layer) Urethane resin 20.0 parts Methyl ethyl ketone 50.0 parts 30.0 parts ethyl acetate • Ink C1 (mask layer) Vinyl chloride / vinyl acetate copolymer (Kaneka Kanevinyl) 30.0 parts Polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd., Yupizeta) 70.0 parts • Ink D (for cushion layer) Toluene 70.3 parts Butyl acetate 12.1 parts Crystalline polyester (Toyobo Byron GA-6400 mp96℃) 14.6 parts Silica filler (Fuji Silicia Chemical Silohobic 100) 3.0 parts • Ink E (for adhesive layer) Modified olefin resin 15 parts Urethane resin 15 parts Methyl ethyl ketone / toluene mixed solvent, 70 parts

[0060] (Example 2) A transfer foil according to Example 2 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C2 with the following composition instead of ink C1. · Ink C2 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 50.0 parts Polycarbonate resin (Yupizeta) 50.0 parts

[0061] (Example 3) A transfer foil according to Example 3 was prepared using the same procedure as in Example 1, except that a mask layer was formed using ink C3 with the following composition instead of ink C1. Ink C3 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 70.0 parts Polycarbonate resin (Yupizeta) 30.0 parts

[0062] (Example 4) A transfer foil according to Example 4 was prepared using the same procedure as in Example 1, except that a mask layer was formed using ink C4 with the following composition instead of ink C1. Ink C4 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 90.0 parts Polycarbonate resin (Yupizeta) 10.0 parts

[0063] (Example 5) A transfer foil according to Example 5 was prepared using the same procedure as in Example 1, except that a mask layer was formed using ink C5 with the following composition instead of ink C1. Ink C5 Vinyl chloride / vinyl acetate copolymer (Nisshin Chemical Industry Solvine M5) 24.0 parts Polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd., Yupizeta) 56.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0064] (Example 6) A transfer foil according to Example 6 was prepared using the same procedure as in Example 1, except that a mask layer was formed using ink C6 with the following composition instead of ink C1. Ink C6 Vinyl chloride / vinyl acetate copolymer (Nisshin Chemical Industry Solvine M5) 40.0 parts Polycarbonate resin (Teijin Panlite) 40.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0065] (Example 7) A transfer foil according to Example 7 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C7 with the following composition instead of ink C1. Ink C7 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 40.0 parts Polycarbonate resin (Yupizeta) 40.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0066] (Comparative Example 1) A transfer foil according to Comparative Example 1 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C8 with the following composition instead of ink C1. Ink C8 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 100.0 parts (Comparative Example 2) A transfer foil according to Comparative Example 2 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C9 with the following composition instead of ink C1. Ink C9 Vinyl chloride / vinyl acetate copolymer (Solvine M5) 100.0 parts

[0067] (Comparative Example 3) A transfer foil according to Comparative Example 3 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C10 with the following composition instead of ink C1. Ink C10 Vinyl chloride / vinyl acetate copolymer (Kanevinyl) 10.0 parts Polycarbonate resin (Yupizeta) 90.0 parts

[0068] (Comparative Example 4) A transfer foil according to Comparative Example 4 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C11 with the following composition instead of ink C1. Ink C11 Vinyl chloride / vinyl acetate copolymer (solvine M5) 16.0 parts Polycarbonate resin (Panlite) 64.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0069] (Comparative Example 5) A transfer foil according to Comparative Example 5 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C12 with the following composition instead of ink C1. Ink C12 Vinyl chloride / vinyl acetate copolymer (solvine M5) 16.0 parts Polycarbonate resin (Yupizeta) 64.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0070] (Comparative Example 6) A transfer foil according to Comparative Example 6 was prepared using the same procedure as in Example 1, except that the mask layer was formed using ink C13 with the following composition instead of ink C1. Ink C13 Vinyl chloride / vinyl acetate copolymer (solvine M5) 8.0 parts Polycarbonate resin (Yupizeta) 72.0 parts Polyethylene wax 3.0 parts Urethane resin 17.0 parts Silica filler 5.0 parts

[0071] For each of the above examples of transfer foils, a light source was placed below, and the transmitted light was observed and imaged from above under magnification. In the acquired images, pinholes formed in the reflective layer 23 appear as white dots. Figures 8 and 9 are magnified transmitted light images of Comparative Examples 1 and 2, respectively. Since both Comparative Examples 1 and 2 had a mask layer consisting solely of a vinyl chloride / vinyl acetate copolymer, no interface formed due to phase separation, resulting in almost no pinholes. The area ratio of pinholes within the observation range was 0.01% for Comparative Example 1 and 0.02% for Comparative Example 2, both below 0.1%.

[0072] Figures 10 to 13 are magnified transmitted light images relating to Examples 1 to 4, respectively. All of these examples have a mask layer made of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, with the ratio of polycarbonate resin to vinyl chloride / vinyl acetate copolymer ranging from 10:90 to 70:30. In all examples, more pinholes were observed compared to Comparative Examples 1 and 2. The area ratio of pinholes within the observation range was 0.5% for Example 1, 1.0% for Example 2, 0.6% for Example 3, and 0.1% for Example 4. The pinhole patterns differed significantly in Examples 1 to 4, confirming that they are sufficiently usable for individual identification of transfer foils or foil bodies. Furthermore, in all examples, the maximum size of the pinholes was 100 μm or less, meaning they were visible under magnified observation of transmitted light but not visible to the naked eye, thus having little effect on the appearance of the transfer foil or foil body.

[0073] Figures 14 and 15 are magnified transmitted light images relating to Comparative Examples 3 and 4, respectively. Although both of these comparative examples have a mask layer made of a combination of vinyl chloride / vinyl acetate copolymer and polycarbonate resin, the ratio of polycarbonate resin to vinyl chloride / vinyl acetate copolymer is 90:10 for Comparative Example 3 and 80:20 for Comparative Example 4, which are outside the range of 10:90 to 70:30. In all examples, larger white spots were observed compared to Examples 1 to 4, indicating that the maximum size of the pinholes was larger. The measured maximum dimensions were 150 μm for Comparative Example 3 and 120 μm for Comparative Example 4. In both cases, the pinholes were visible to the naked eye under reflected light, confirming that they affected the appearance.

[0074] [Table 1]

[0075] Table 1 shows the overall results for the examples and comparative examples, including those for which images were not shown. In all examples, both the area ratio and the maximum size of the pinholes were within a good range, and it was confirmed that individual identification using these pinholes could be performed effectively. Furthermore, no adverse effects from additives other than resin in the mask layer were observed. On the other hand, in the comparative examples, at least one of the area ratio and the maximum size was outside the good range, and both individual identification and a good appearance could not be achieved.

[0076] Although one embodiment of the present invention has been described above, the specific configuration is not limited to this embodiment, and modifications and combinations of the configuration that do not depart from the spirit of the present invention are also included. [Explanation of Symbols]

[0077] 1 Transfer foil 10 Support 21 Surface protective layer 22 Optical forming layer 23 Reflective layer 30 mask layers 33, p1, p2, p3, p4, p5, p6, p7 pinholes 40 cushion layer 50 Adhesive layer 60 Foil body

Claims

1. A transfer foil comprising a support and a foil body to be bonded to a transfer object, The aforementioned foil body is A surface protective layer provided on the support, An optical forming layer provided on the surface protective layer, A reflective layer made of metal is provided on the optical forming layer, A mask layer formed on the reflective layer, A cushion layer provided on the mask layer, The cushion layer comprises an adhesive layer provided on the cushion layer, The reflective layer has multiple pinholes with a maximum size of 100 μm or less. The ratio of the area of ​​the pinholes to the area of ​​the reflective layer is 0.1% or more and 5% or less. Transfer foil.

2. The mask layer is composed of at least two types of resin and has a sea-island structure made of the two types of resin. The transfer foil according to claim 1.

3. One of the two types of resins is resin A, which has saturated bonds in its main chain, and the other is resin B, which has a cyclic structure in its main chain. The transfer foil according to claim 2.

4. The aforementioned resin A is an elastomer, and the aforementioned resin B is an aromatic resin. The transfer foil according to claim 3.

5. The resin A is a vinyl chloride / vinyl acetate copolymer, and the resin B is a polycarbonate resin. The transfer foil according to claim 3.

6. The mass ratio of resin A to resin B is within the range of 90:10 to 70:

30. The transfer foil according to claim 5.

7. Authentication method using a transfer foil according to any one of claims 1 to 6, Based on the nature of the pinholes in the reflective layer, the transfer material to which the foil body is joined is authenticated as genuine. Authentication method.

8. The embodiment of the pinhole includes at least one of the number of pinholes, the location of the pinholes, the total area of ​​the pinholes, and the maximum dimensions of the pinholes. The authentication method according to claim 7.

Images