Laminated sheet and press-through pack using same

Abstract

[Problem] To provide a laminated sheet in which it cannot be known that a forgery prevention means is applied. [Solution] This laminated sheet comprises at least a heat seal layer, a metal foil layer, a print base layer, a print layer, and a protective layer. A fluorescent colorant is blended into the print base layer, and the absolute value of the difference between the a-value of the print base layer in the visible light band and the a-value of the print base layer in the ultraviolet band in the CIE 1976 L*a*b* color space is adjusted to 5 or greater, or the absolute value of the difference between the b-value of the print base layer in the visible light band and the b-value of the print base layer in the ultraviolet band in the CIE 1976 L*a*b* color space is adjusted to 5 or greater.

Description

Laminated Sheet and Press-Through Pack Using the Same

[0001] The present invention relates to a laminated sheet and a press-through pack using the laminated sheet as a lid material.

[0002] Press-through packs (referred to as PTPs, etc.) are commonly used as packages for individually accommodating drugs such as tablets. A press-through pack is composed of a storage portion that stores a drug and a lid material that covers the storage portion, and adopts a configuration in which the drug is pushed from the storage portion side to break through the lid material and take out the drug.

[0003] A PTP lid material has a multilayer structure in which a heat seal layer for bonding the lid material to the storage portion is laminated on a metal foil layer such as aluminum foil, and usually further includes a printed layer for printed display that indicates the product name of the drug and the like. This printed layer contains information on the drug stored in the storage portion and information on the manufacturer and the like.

[0004] In recent years, from the viewpoint of preventing drug counterfeiting and preventing medical accidents such as drug mix-ups and expiration of validity periods, more detailed information has been provided on the storage portion or lid material of PTPs. For example, a hologram sticker is attached to the lid material of a PTP (Patent Document 1, etc.), or fine embossing is performed on the surface of the lid material to provide a latent image pattern (Patent Document 2, etc.). However, problems still remain, such that even if a counterfeit hologram sticker is attached, users may not notice that it is a counterfeit drug, and special equipment is required to perform fine embossing on the surface of the lid material.

[0005] In response to the above problems, Patent Document 3 proposes providing a light-emitting layer containing a taggant pigment that fluoresces at a specific wavelength on a PTP lid material. According to the PTP lid material, the authenticity of the drug can be determined by visually recognizing the fluorescent light emitted from the taggant pigment, and the authenticity of the drug can also be determined by detecting the fluorescent light with a detection device and collating it with data of a genuine product (Patent Document 3, etc.).

[0006] Japanese Patent Application Laid-Open No. 2005-212811, Japanese Patent Application Laid-Open No. 2007-145428, Japanese Patent Application Laid-Open No. 2021-8306

[0007] In the PTP lid material of Patent Document 3, since Tagant pigment with an average particle diameter larger than the thickness of the luminescent layer is used, irregularities are formed on the surface of the luminescent layer. Therefore, if the luminescent layer is provided over the entire surface of the lid material, its presence cannot be recognized. However, if the luminescent layer is provided on only a part of the surface of the lid material in a predetermined pattern such as letters or figures, the presence of the luminescent layer can be seen due to the irregularities caused by the Tagant pigment, and thus it becomes possible to know that the lid material is equipped with an anti-counterfeiting measure.

[0008] Therefore, the object of the present invention is to provide a laminated sheet in which it is impossible to know that counterfeit prevention measures have been implemented.

[0009] The present inventors have found that by providing a printed underlayment layer in a laminated sheet that exhibits different colors under visible light and under ultraviolet light, it is possible to realize a laminated sheet in which it is impossible to know that counterfeit prevention measures have been taken. The present invention is based on this finding. The gist of the present invention is as follows: [1] A laminated sheet comprising at least a heat seal layer, a metal foil layer, a printed underlayment layer, a printed layer, and a protective layer, wherein the printed underlayment layer contains a fluorescent colorant, and the absolute value of the difference between the a value of the printed underlayment layer in the visible light band and the a value in the ultraviolet light band in the CIE1976L*a*b* color space is 5 or more, or the absolute value of the difference between the b value of the printed underlayment layer in the visible light band and the b value in the ultraviolet light band in the CIE1976L*a*b* color space is 5 or more. [2] The laminated sheet according to [1], wherein the visible light band is under a solar light source. [3] The laminated sheet according to [1] or [2], wherein the ultraviolet light is UV-A with a wavelength of 375 nm. [4] The laminated sheet according to any one of [1] to [3], wherein the printed base layer further comprises a white coloring agent. [5] The laminated sheet according to any one of [1] to [4], further comprising a printed layer between the heat seal layer and the metal foil layer. [6] The laminated sheet according to any one of [1] to [5], used as a lid material for a press-through pack. [7] A press-through pack comprising: a lid material made of the laminated sheet according to any one of [1] to [6]; and a bottom material having a recess capable of accommodating contents and a flange portion provided around the recess that is bonded to the lid material, wherein the heat seal layer of the laminated sheet and the flange portion of the bottom material are heat-sealed.

[0010] The laminated sheet of the present invention is equipped with a printing underlayment that exhibits different colors under visible light and under ultraviolet light, thereby providing an anti-counterfeiting measure that is not visible under visible light. Therefore, it can be suitably used as a lid material for press-through packs in which it is impossible to know that an anti-counterfeiting measure has been applied.

[0011] Figure 1 shows a cross-sectional view in the thickness direction of a laminated sheet according to one embodiment of the present invention. Figure 2 shows a cross-sectional view in the thickness direction of a laminated sheet according to another embodiment of the present invention. Figure 3 shows a cross-sectional view in the thickness direction of a press-through pack according to one embodiment of the present invention.

[0012] [Laminated Sheet] The laminated sheet of the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view in the thickness direction of a laminated sheet according to one embodiment of the present invention. The laminated sheet 1 comprises, at least in this order, a heat seal layer 10, a metal foil layer 20, a printing base layer 30, a printing layer 40, and a protective layer 50. The printing base layer 30 exhibits different colors under visible light and under ultraviolet light. The printing layer 40 is visible under visible light, and various information is printed on it, for example, with black ink. For example, when the laminated sheet of the present invention is used as a lid material for a press-through pack of pharmaceuticals, information about the pharmaceuticals is printed on the printing layer 40 as textual information such as the manufacturer's information and graphic information (for example, a barcode). On the other hand, because the printing base layer 30 exhibits different colors under visible light and under ultraviolet light, when the laminated sheet 1 is observed from the side of the protective layer 50, it is not possible to know that the laminated sheet 1 is equipped with anti-counterfeiting measures under visible light. On the other hand, when ultraviolet light is irradiated from the protective layer 50 side of the laminated sheet 1, the printed underlayment layer 30 changes to a different color tone than under visible light, thus enabling the detection of counterfeit prevention measures and making it possible to determine the authenticity of products (for example, pharmaceuticals, etc.) equipped with the laminated sheet of the present invention. The following describes each layer constituting the laminated sheet of the present invention.

[0013] <Heat Seal Layer> The heat seal layer is the outermost layer of the laminated sheet. For example, when the laminated sheet of the present invention is used as a lid material for a press-through pack, this layer is provided to heat seal with the flange portion of the bottom material of the press-through pack to bond the lid material and the bottom material. The heat seal layer can be formed from a conventionally known heat-sealable resin, such as a polyolefin-based (polyethylene-based, polypropylene-based) heat-sealable resin or an unstretched or stretched film thereof.

[0014] Furthermore, when the laminated sheet of the present invention is used as a lid material for a press-through pack, the heat-seal layer can be formed by applying a resin coating agent, mainly composed of a mixture of the same type of resin as that which constitutes the bottom material of the press-through pack (described later), using gravure coating or the like.

[0015] The thickness of the heat seal layer is not particularly limited, but is usually around 1.0 to 50.0 μm, and is more preferably 2.0 to 10.0 μm from the viewpoint of sealing performance, etc.

[0016] <Metal Foil Layer> As the metal foil used in the metal foil layer, materials used in known PTP lid materials can be adopted, and for example, metal foils such as aluminum foil, copper foil, gold foil, and silver foil can be suitably used. In addition, in the present invention, a sheet or film containing a metal vapor deposition layer such as an aluminum vapor deposition layer can also be adopted as a base material. For example, a laminated film in which a metal vapor deposition layer is formed on the surface of a resin film or the like by a known vapor deposition method (PVD, CVD, etc.) can be adopted as a base material. Examples of resin films used here include polyamide (nylon), polyethylene (especially high-density polyethylene), polypropylene (especially stretched polypropylene), vinyl chloride, ethylene-vinyl alcohol copolymer, polyethylene naphthalate, polyethylene terephthalate, etc. Among these, it is preferable to use aluminum foil for the metal foil layer.

[0017] Examples of aluminum foil include pure aluminum (JIS (AA) 1000 series, e.g., 1N30, 1070, 1100, etc.), Al-Mn series (JIS (AA) 3000 series, e.g., 3003, 3004, etc.), Al-Mg series (JIS (AA) 5000 series), and Al-Fe series (JIS (AA) 8000 series, e.g., 8021, 8079, etc.). Among these, aluminum foil with materials (compositions) such as 1N30, 1070, 1100, 3003, 8021, and 8079 as defined by JIS, etc., can be suitably used.

[0018] The aluminum foil can be molded, degreased and cleaned, anchored, overcoated, and surface-treated using known methods as needed.

[0019] The thickness of the metal foil layer is not particularly limited, but considering the moisture resistance and strength of the laminated sheet, and the handling when the laminated sheet of the present invention is used as a lid material for a press-through pack, it is usually about 5 to 500 μm, and preferably 100 to 250 μm.

[0020] <Printing Underlayer> A printing underlayer is provided on the underside of the printing layer of the laminated sheet of the present invention to make the information about the drug, which is printed on the printing layer as textual information or graphic information (such as a barcode) of the manufacturer, easily visible under visible light, and to further provide design features as needed.

[0021] The printing underlayer also serves as a base layer for the printing layer, supporting it. The printing underlayer may be directly provided on the surface of the metal foil layer described above, or it may be laminated between the metal foil layer and the printing underlayer via a primer layer or the like (not shown) to facilitate the formation of the printing underlayer.

[0022] The printed underlayer exhibits different color tones under visible light (i.e., the visible light band) and ultraviolet light (i.e., the ultraviolet light band). Specifically, "under visible light" and "visible light band" refer to irradiation with one or more specific wavelengths of light within the wavelength range of 380 to 780 nm, and in one embodiment, it refers to irradiation with multiple wavelengths of light contained in sunlight (i.e., under a solar light source). Furthermore, "exhibiting different color tones" under visible light and ultraviolet light specifically means that the absolute difference between the a value of the printed underlayer in the visible light band and the a value of the printed underlayer in the ultraviolet light band in the CIE 1976 L*a*b* color space is 5 or more, or the absolute difference between the b value of the printed underlayer in the visible light band and the b value of the printed underlayer in the ultraviolet light band in the CIE 1976 L*a*b* color space is 5 or more. The printing underlayer is defined as having an absolute difference of 6 or greater, 7 or greater, or 8 or greater between the a value in the visible light band and the a value in the ultraviolet light band in the CIE 1976 L*a*b* color space, or an absolute difference of 6 or greater, 7 or greater, or 8 or greater between the b value in the visible light band and the b value in the ultraviolet light band in the CIE 1976 L*a*b* color space. The a and b values ​​in the visible light band and ultraviolet light band of the printing underlayer in the CIE 1976 L*a*b* color space can be measured using a spectrofluorometer (FP-8050 series, manufactured by JASCO Corporation).

[0023] In one embodiment, the printing underlayer contains pigments or dyes that exhibit different color tones under ultraviolet light and visible light. For example, when forming a printing underlayer such that the color tone under visible light is white, the printing underlayer can be formed using an ink containing a colorant that exhibits white under visible light but a different color tone (e.g., a fluorescent color) under ultraviolet light, particularly a fluorescent colorant (e.g., a fluorescent pigment, a fluorescent dye, etc.).

[0024] The fluorescent colorants that exhibit a different color tone under ultraviolet light than under visible light are not particularly limited, and known pigments and dyes can be used. For example, sulfides such as zinc, cadmium, barium, strontium, and yttrium, or fluorescent pigments such as auramine tungstate, rhodamine tungstate, and sodium red lake, or fluorescent dyes such as diaminostilbene, perylene, coumarin, triazole, carbazole, pyridine, naphthalic acid, imidazolon, and their derivatives can be used. These fluorescent colorants may be used individually or in combination of two or more.

[0025] Among the fluorescent colorants mentioned above, fluorescent colorants that have an absorption peak at a wavelength of 375 nm in UV-A and emit light in the ultraviolet light band are preferably used as fluorescent colorants included in the printing underlayer. Examples of such fluorescent pigments and dyes include YS-A4 and ALN-BP4 manufactured by Nemoto Special Chemicals Co., Ltd.

[0026] The upper limit of the average particle size d50 of the fluorescent colorant can be, for example, 10.0 μm, 8.0 μm, 6.0 μm, 5.0 μm, 4.0 μm, 3.0 μm, 2.0 μm, 1.0 μm, 0.5 μm, or 0.1 μm, with 5.0 μm being preferred and 2.0 μm being more preferred. In particular, it is preferable to use a fluorescent colorant with an average particle size smaller than the thickness of the printed underlayment. By using a fluorescent colorant with an average particle size smaller than the thickness of the printed underlayment, no part of the fluorescent colorant protrudes from the surface of the printed underlayment, making it impossible to see the printed underlayment under visible light and thus making it impossible to know that anti-counterfeiting measures have been taken. On the other hand, the lower limit of the average particle size d50 of the fluorescent colorant can be, for example, 0.1 μm, 0.5 μm, or 1.0 μm. Furthermore, the range of the average particle size d50 of the fluorescent colorant can be set by appropriately combining the upper and lower limits mentioned above. In this specification, the average particle diameter refers to the average particle diameter (d50) that includes not only the particle diameter of primary particles but also the particle diameter of secondary particles (aggregates), and is the volume-based d50 value measured by laser diffraction.

[0027] The amount of fluorescent colorant in an ink for forming a printing underlay can be appropriately set considering the coating properties of the ink when forming the printing underlay and the visibility of the printing underlay under ultraviolet light. The upper limit of the amount of fluorescent colorant in the ink can be, for example, 90%, 80%, 70%, 60%, 50%, or 40% by mass, calculated on a solids basis (components other than solvent). On the other hand, the lower limit of the amount of fluorescent colorant in the ink can be, for example, 5%, 10%, 15%, 20%, 25%, or 30% by mass, calculated on a solids basis (components other than solvent). Furthermore, the range of the amount of fluorescent colorant in the ink can be set by appropriately combining the upper and lower limits mentioned above. The amount of fluorescent colorant in the ink is usually about 10 to 80% by mass, preferably 20 to 60%, and more preferably 25 to 60% by mass, calculated on a solids basis (components other than solvent).

[0028] The printing underlayer can be formed by using an ink for forming a printing underlayer that contains the fluorescent colorant described above. Specifically, the printing underlayer can be formed by applying the ink for forming a printing underlayer to a metal foil layer (or any other layer if one is provided) and drying it.

[0029] The method for applying the ink for forming the printing underlayer is not particularly limited and can be applied by methods such as gravure roll coater, offset printing, flexographic printing, UV printing, or curtain flow coater. The ink for forming the printing underlayer can also be applied by spraying or the like.

[0030] The printing underlayer is formed by applying an ink for forming the printing underlayer and then drying the coated film. The drying method of the coated film may be either natural drying or heat drying. If heat drying is used, it can be heated to a temperature of, for example, 50 to 160°C. Furthermore, when applying the ink for forming the printing underlayer, the above application and drying process may be repeated two or more times to obtain a predetermined thickness.

[0031] The upper limit of the thickness of the printing underlay is not particularly limited, but for example, it can be 20.0 μm, 15.0 μm, 10.0 μm, 9.0 μm, 8.0 μm, 7.0 μm, 6.0 μm, 5.0 μm, 4.0 μm, or 3.0 μm. On the other hand, the lower limit of the thickness of the printing underlay is not particularly limited, but for example, it can be 0.1 μm, 0.3 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.5 μm, or 2.0 μm. Furthermore, the range of the thickness of the printing underlay can be set by appropriately combining the upper and lower limits mentioned above. The thickness of the printing underlay is usually about 0.5 to 10.0 μm, and from the viewpoint of opacity, it is preferable to have a thickness of 1.0 to 5.0 μm.

[0032] The resin component of the ink for forming the printing underlayer is not particularly limited, but a transparent resin can be suitably used. Such resin components are not particularly limited, but epoxy resins, vinyl chloride-vinyl acetate copolymer resins, nitrocellulose resins, polypropylene resins, polyvinyl butyral resins, phenolic resins, maleic acid resins, alkyd resins, chlorinated polypropylene resins, acrylic resins, modified olefin resins, etc., can be suitably used. These resin components may be used individually or in combination of two or more. Among the above-mentioned resin components, epoxy resins can be suitably used from the viewpoint of coating film performance, etc.

[0033] The ink for forming the printing underlayer may further contain a white coloring agent as a coloring component, if necessary. The white coloring agent is not particularly limited as long as the effects of the present invention are achieved, and inorganic fillers such as barium sulfate, barium titanate, silicon dioxide powder, amorphous silica, talc, calcined talc, and titanium dioxide can be used. Among these coloring component, talc and calcined talc can be preferably used from the viewpoint of color development of the printing underlayer in the ultraviolet light band.

[0034] The upper limit of the average particle size d50 of the white colorant can be, for example, 5.0 μm, 4.0 μm, 3.0 μm, 2.0 μm, 1.0 μm, or 0.5 μm. On the other hand, the lower limit of the average particle size d50 of the white colorant can be, for example, 0.1 μm, 0.2 μm, 0.3 μm, or 0.4 μm. Furthermore, the range of the average particle size d50 of the white colorant can be set by appropriately combining the upper and lower limits mentioned above.

[0035] The content of the white colorant in the ink for forming the printing underlay can be appropriately set considering the coating properties of the ink when forming the printing underlay and the visibility of the printing underlay under ultraviolet light. The upper limit of the white colorant content in the ink can be, for example, 90% by mass, 80% by mass, 70% by mass, 60% by mass, 50% by mass, or 40% by mass, on a solid content (components other than solvent) basis. On the other hand, the lower limit of the white colorant content in the ink can be, for example, 5% by mass, 10% by mass, 15% by mass, 20% by mass, 25% by mass, or 30% by mass, on a solid content (components other than solvent) basis. Furthermore, the range of the white colorant content in the ink can be set by appropriately combining the upper and lower limits mentioned above. The white colorant content in the ink is preferably 20 to 60% by mass, and more preferably 25 to 60% by mass, on a solid content (components other than solvent) basis.

[0036] The ink for forming the printing underlayer may contain a solvent to adjust its viscosity to a level suitable for coating. Examples of solvents include organic solvents such as aromatic hydrocarbons like toluene and xylene, alicyclic hydrocarbon solvents like methylcyclohexane and cyclohexane, ester solvents like ethyl acetate and butyl acetate, ketone solvents like methyl ethyl ketone and acetone, and alcohol solvents like isopropyl alcohol and denatured ethanol. These solvents may be used individually or in combination of two or more.

[0037] The ink for forming the printing underlayer may contain a curing catalyst as needed. Examples of curing catalysts include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. The curing catalyst is not limited to these, and may be a thermosetting catalyst for epoxy resins or oxetane compounds, or any catalyst that promotes the reaction between at least one of an epoxy group and an oxetanyl group and a carboxyl group. In addition, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine isocyanuric acid adduct may be used as the curing catalyst, and preferably these compounds that also function as adhesion imparters are used in combination with the thermosetting catalyst. The curing catalyst may be used alone or in combination of two or more types.

[0038] The ink for forming the printing underlayer may contain additives such as dispersants, surfactants, leveling agents, surface modifiers, anti-sagging agents, thickeners, defoamers, and lubricants, to the extent that they do not interfere with the effects of the present invention.

[0039] <Printed Layer> The printed layer is a layer formed on at least a portion of the surface of the printing base layer described above, and is the layer on which information such as textual information and graphic information is printed. As textual information, for example, immutable information such as the product name, dosage, efficacy, and effects of a drug, as well as variable information such as the manufacturing date, lot number, and expiration date, can be printed. As graphic information, marks and barcodes can be printed.

[0040] The color tone of the ink for forming the printing layer can be appropriately determined considering the visibility and design of the printed text and graphic information. However, when ΔE is defined as the color difference in the CIEL*a*b* color space between the color tone of the printing underlayment and the color tone of the printing layer under visible light, it is preferable that ΔE calculated from the CIE DE2000 color difference formula be 5.0 or more, and more preferably 10.0 or more.

[0041] In one embodiment, when the ink for forming the printing underlayment is white under visible light, the printing layer can be formed using an ink having a color tone such as black, dark blue, or brown, in order to make the color difference ΔE between the color tone of the printing underlayment and the color tone of the printing layer under visible light preferably 5.0 or more, and more preferably 10.0 or more. Examples of pigments used in inks having a color tone such as black, dark blue, or brown include carbon black and phthalocyanine blue.

[0042] Text and graphic information on the print layer may be printed using only a single color of ink, but for example, text information and graphic information may be printed using different colored inks.

[0043] <Protective Layer> The protective layer is provided to protect the printed layer (or the printed layer and the underlying layer if the printed layer is formed on only a part of the underlying layer) from abrasion and the like. Preferably, the protective layer is provided over the entire surface of the laminated film so as to cover the printed layer (and optionally the underlying layer). The protective layer can be formed on the printed layer (and optionally the underlying layer) by the same coating means as described above, using an ink containing resin components such as vinyl chloride resin, nitrocellulose resin, epoxy resin, acrylic resin, urethane resin, melamine resin, or ester resin.

[0044] The thickness of the protective layer is not particularly limited, and is normally 0.5 to 10.0 µm. From the viewpoint of protecting the first print layer, it is more preferably 1.0 to 5.0 µm.

[0045] FIG. 2 is a cross-sectional view in the thickness direction of a laminated sheet according to another embodiment of the present invention. As shown in FIG. 2, the laminated sheet 1 includes a heat seal layer 10, a metal foil layer 20, a print base layer 30, a print layer 40 (a first print layer 40A), and a protective layer 50. As an additional layer, another print layer 40 (a second print layer 40B) may be provided between the heat seal layer 10 and the metal foil layer 20. Since the second print layer 40B may have the same configuration as the above-described print layer, description thereof is omitted herein.

[0046] [Press-Through Pack] FIG. 3 is a cross-sectional view in the thickness direction of a press-through pack according to one embodiment of the present invention. The press-through pack 2 includes a lid member 60 formed of the above-described laminated sheet 1 and a bottom member 70. The bottom member 70 includes a recessed portion 80 capable of accommodating contents and a flange portion 90 provided around the recessed portion 80 and bonded to the lid member 60. After contents 100 such as a drug (tablet) are accommodated in the recessed portion 80, the heat seal layer 10 of the laminated sheet 1 constituting the lid member 60 and the flange portion 90 of the bottom member 70 are heat-sealed.

[0047] For the heat sealing, known heating methods such as ultrasonic heat sealing, high-frequency heat sealing, and electric heater head heat sealing can be applied.

[0048] The method for molding the bottom member including the above-described recessed portion and the flange portion provided around the recessed portion is not particularly limited, and known methods can be employed, such as a heated pressure air molding method in which a resin film is heated and pressed against a predetermined mold, a drum-type vacuum molding method in which pressure molding is performed while drawing a material film into a recessed portion of a drum under vacuum, a plug molding method in which uneven molds are pressed against a resin film from above and below, and a pin molding method. The number and shape of the recessed portions can be appropriately determined according to the contents (drug) to be accommodated.

[0049] The resin film used for the base material can be any moldable resin film as described above without particular limitations. Examples include polyethylene, polypropylene, polyolefins such as ethylene-α-olefin copolymer, polystyrene, polycarbonate, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyphenylene ether, polyethersulfone, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyphenylene sulfide, polyacrylonitrile, and fluororesin. Among these, it is preferable to select and use a resin with high gas barrier properties. Specifically, examples include ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, and liquid crystal polymer. Furthermore, films made of these resins can also be used in laminated form.

[0050] There are no particular restrictions on the thickness of the resin film used as the base material, but it is usually around 30 to 2000 μm, and preferably 50 to 500 μm.

[0051] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0052] <Preparation of inks for forming the printing base layer> Each component was blended according to the composition shown in Table 1 below, pre-mixed in a stirrer, and then kneaded in a three-roll mill to obtain inks 1 to 8 for forming the printing base layer. Note that the numerical values ​​of each component in Table 1 all represent parts by mass.

[0053]

[0054] The components *1 to *8 in Table 1 are as follows: *1: Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation) *2: 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) *3: Fluorescent inorganic pigment (manufactured by Nemoto Special Chemicals Co., Ltd., average particle size d50: 2.0 μm) *4: Fluorescent inorganic pigment (manufactured by Nemoto Special Chemicals Co., Ltd., average particle size d50: 2.0 μm) *5: Fluorescent inorganic pigment (manufactured by Tailnavi Co., Ltd., average particle size d50: 2.0 μm) *6: Titanium dioxide R-38L (manufactured by Sakai Chemical Industry Co., Ltd., average particle size d50: 0.4 μm) *7: Talc MP15-38 (manufactured by Fimatec Co., Ltd., average particle size d50: 2.0 μm) *8: Propylene glycol monomethyl ether acetate

[0055] [Example 1] A soft aluminum foil (material 1N30) with a thickness of 200 μm was prepared as the metal foil layer. Ink 1 for forming a printing base layer was applied to the entire surface of one side of the foil by screen printing, and the foil was dried in a hot air circulating drying oven at 150°C for 15 seconds to form a sheet having a printing base layer with a thickness of 3.0 μm.

[0056] The color tone of the printed underlay layer of the sheet obtained as described above was measured under visible light (indoor fluorescent lamp) using a spectrofluorometer (FP-8050 series, manufactured by JASCO Corporation). Specifically, the a and b values ​​of the printed underlay layer in the CIE1976L*a*b* color space were measured, respectively.

[0057] Next, the printed underlayer of the sheet obtained as described above was irradiated with ultraviolet light (UV-A) under visible light (indoor fluorescent lamp), and the a and b values ​​of the printed underlayer in the CIE 1976 L*a*b* color space were measured. Furthermore, the printed underlayer of the sheet obtained as described above was irradiated with ultraviolet light (UV-A) in a darkroom, and the a and b values ​​of the printed underlayer in the CIE 1976 L*a*b* color space were measured.

[0058] The absolute difference (Δa) between the a value under visible light without ultraviolet light irradiation and the a value under visible light with ultraviolet light irradiation or in a darkroom with ultraviolet light irradiation was calculated. The results are shown in Table 2 below. Furthermore, the absolute difference (Δb) between the b value under visible light without ultraviolet light irradiation and the b value under visible light with ultraviolet light irradiation or in a darkroom with ultraviolet light irradiation was calculated. The results are shown in Table 2. Note that the a value and b value, as well as their absolute differences Δa and Δb, do not substantially change depending on the presence or absence of a printing layer or protective layer, and therefore, the presence or absence of a printing layer or protective layer does not substantially affect the results in Table 2.

[0059] <Color development (visual inspection) when irradiated with ultraviolet light under visible light> The laminated sheet obtained as described above was irradiated with UV-A light with a wavelength of 375 nm (manufactured by CONTEC Co., Ltd.) from the printed underlayment side under visible light (indoor fluorescent light), and the color development was confirmed visually. The results are shown in Table 2. ○: Color developed ×: No color developed

[0060] <Color development (visual inspection) when irradiated with ultraviolet light in a darkroom> The laminated sheet obtained as described above was irradiated with UV-A light with a wavelength of 375 nm (manufactured by CONTEC Co., Ltd.) from the printed underlayer side in a darkroom, and the color development was confirmed visually. The results are shown in Table 2. ○: Color developed ×: No color developed, or color developed but not at a recognizable level

[0061] [Example 2] A sheet of Example 2 was prepared in the same manner as in Example 1, except that ink 2 for forming the printing underlay was used as the ink for forming the printing underlay, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0062] [Example 3] A sheet of Example 3 was prepared in the same manner as in Example 1, except that ink 3 for forming the printing underlayer was used as the ink for forming the printing underlayer, and the evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

[0063] [Example 4] A sheet of Example 4 was prepared in the same manner as in Example 1, except that ink 4 for forming the printing underlay was used as the ink for forming the printing underlay, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0064] [Comparative Example 1] A sheet of Comparative Example 1 was prepared in the same manner as in Example 1, except that ink 5 for forming the printing underlayer was used as the ink for forming the printing underlayer, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0065] [Comparative Example 2] A sheet of Comparative Example 2 was prepared in the same manner as in Example 1, except that ink 6 for forming the printing underlayer was used as the ink for forming the printing underlayer, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0066] [Comparative Example 3] A sheet of Comparative Example 3 was prepared in the same manner as in Example 1, except that ink 7 for forming the printing underlayer was used as the ink for forming the printing underlayer, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0067] [Comparative Example 4] A sheet for Comparative Example 4 was prepared in the same manner as in Example 1, except that ink 8 for forming the printing underlayer was used as the ink for forming the printing underlayer, and the sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0068]

[0069] As is clear from the evaluation results in Table 2, sheets (Examples 1-4) in which the printing underlayer contains a fluorescent colorant and the absolute difference between the a value in the visible light band and the a value in the ultraviolet light band of the printing underlayer in the CIE 1976 L*a*b* color space is 5 or more, or the absolute difference between the b value in the visible light band and the b value in the ultraviolet light band of the printing underlayer in the CIE 1976 L*a*b* color space is 5 or more, show clear color development when irradiated with ultraviolet light, both under visible light and in a dark room. Therefore, it can be seen that by forming a printing underlayer using inks 1-4, it becomes possible to determine authenticity by ultraviolet light irradiation, and an anti-counterfeiting effect can be obtained.

[0070] On the other hand, in sheets (Comparative Examples 1-4) where the printed underlayer does not contain a fluorescent colorant, the absolute difference between the a value in the visible light band and the a value in the ultraviolet light band of the printed underlayer in the CIE 1976 L*a*b* color space is not 5 or more, and the absolute difference between the b value in the visible light band and the b value in the ultraviolet light band of the printed underlayer in the CIE 1976 L*a*b* color space is not 5 or more, it can be seen that no clear color development is observed when irradiated with ultraviolet light, both under visible light and in a dark room. Therefore, when inks 5-8 are used to form the printed underlayer, it is not possible to determine authenticity by ultraviolet light irradiation, and no anti-counterfeiting effect can be obtained.

[0071] 1. Laminated sheet 2. Press-through pack 10. Heat-seal layer 20. Metal foil layer 30. Printing base layer 40. Printing layer 50. Protective layer 60. Lid material 70. Bottom material 80. Recess 90. Flange section 100. Contents

Claims

1. A laminated sheet comprising at least a heat seal layer, a metal foil layer, a printing base layer, a printing layer, and a protective layer, wherein the printing base layer contains a fluorescent colorant, and the absolute difference between the a value of the printing base layer in the visible light band and the a value in the ultraviolet light band in the CIE 1976 L*a*b* color space is 5 or more, or the absolute difference between the b value of the printing base layer in the visible light band and the b value in the ultraviolet light band in the CIE 1976 L*a*b* color space is 5 or more.

2. The laminated sheet according to claim 1, wherein the visible light band is under solar light.

3. The laminated sheet according to claim 1, wherein the ultraviolet light is UV-A with a wavelength of 375 nm.

4. The laminated sheet according to claim 1, wherein the printed underlayer further comprises a white coloring agent.

5. The laminated sheet according to claim 1, further comprising a printing layer between the heat-seal layer and the metal foil layer.

6. The laminated sheet according to claim 1, used as a lid material for a press-through pack.

7. A press-through pack comprising: a lid material made of a laminated sheet as described in claim 1; and a bottom material having a recess capable of accommodating contents and a flange portion provided around the recess that is bonded to the lid material, wherein the heat-seal layer of the laminated sheet and the flange portion of the bottom material are heat-sealed.

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