Laminate, method for identifying laminate, and method for manufacturing recycled substrate.

Abstract

We provide a laminated material with superior design quality and the ability to acquire information through image recognition. [Solution] A laminate comprising a substrate, a near-infrared light transmitting visible light shielding layer, and a near-infrared light identifiable information layer. The laminate wherein the substrate is made of one of a polyolefin resin film, a polyester resin film, and a polyamide resin film. The laminate wherein the total light transmittance of the substrate, as measured in accordance with JIS K 7361-1, is 50% or more. The laminate wherein the thickness of the substrate is 10 μm or more and 1000 μm or less.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a laminate that can be sorted by near-infrared light, a method for identifying a laminate using near-infrared light, and a method for manufacturing a recycled substrate using the identification method. [Background technology]

[0002] From the perspective of environmental protection and the efficient use of resources, various studies are being conducted on the recycling of plastic products. In recent years, the demand for recycling has been particularly high in order to realize a circular economy.

[0003] Generally, among plastic products, laminated plastic film packaging materials (hereinafter referred to as film packaging materials) have a multi-layer structure to meet different performance requirements depending on the application. For this reason, recycling film packaging materials is generally difficult. For example, film packaging materials such as food packaging and refill pouches for sanitary products such as detergents are called flexible packaging materials and have a multi-layer structure using multiple materials such as printing ink and adhesive between plastic base materials such as polyolefin or polyester. For this reason, even though film packaging materials contain recyclable plastic base materials, they are often incinerated as waste or disposed of unused in landfills, etc.

[0004] Therefore, in order to expand the recycling of collected film packaging materials, a technology is needed that allows for the separation and recovery of recyclable packaging materials in the film packaging material separation process, for example, single-layer packaging materials using only one layer of plastic substrate and monomaterial packaging materials formed with a multi-layer structure using the same material, and further allows for the efficient recovery and regeneration of recyclable materials from the separated items. For example, Patent Document 1 discloses a method of embedding recycling information into the PET bottle body and separating based on that information. Patent Document 2 discloses a method of identifying polyester film containing fine silica particles using an optical spectrometer reader. Patent Document 3 discloses a method for manufacturing a recyclable substrate by improving the technology described in Patent Document 1. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Public Gazette 2020 / 186234 [Patent Document 2] Japanese Patent Publication No. 2023-041655 [Patent Document 3] Japanese Patent Publication No. 2022-182777 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the method disclosed in Patent Document 1 is intended for the separate collection of PET bottles, and involves directly forming indentations on the PET bottle body using laser marking to add recycling information. To form indentations using laser marking, the substrate needs to have a certain thickness, like a PET bottle. Therefore, it is difficult to apply the disclosed method to film packaging materials that are thinner than PET bottles. The method disclosed in Patent Document 2 requires the use of special materials such as fine silica particles, which limits its use in food packaging applications due to safety and hygiene concerns, and its high material cost makes widespread adoption difficult. Patent Document 3 exemplifies digital watermarking, barcodes, QR codes (registered trademark), and identification methods using fluorescent X-ray analysis. However, when using barcodes or QR codes (registered trademark) in the method described in Patent Document 3, it is necessary to allocate an appropriate area on the laminate or part of the packaging material to apply the code, which limits the design in order to secure the area for allocation. Digimarc Barcode (registered trademark), which is exemplified as digital watermarking, is a technology that forms a pattern layer with minute codes, but even though they are minute, the codes are present in a position that can be discerned from the surface, which can interfere with delicate designs. Furthermore, in white areas without a pattern layer, it is necessary to insert a tiny code in another color or in white, which affects the whiteness and opacity of the white areas. On the other hand, with X-ray fluorescence analysis, many of the detectable elements and compounds have no track record of being used in food packaging applications, making practical application difficult from a safety, hygiene, and cost perspective. Moreover, there is little track record of industrial practical application of imaging technology using dynamic detection by X-ray fluorescence analysis, and in practice, it only identifies the presence or absence of markers contained in the packaging material, resulting in limitations in the amount of information that can be obtained. Under these circumstances, in lamination sorting and recovery technologies, there is a need for technologies that do not impair the design quality of the lamination, can be industrialized for a variety of applications, and can provide more information, for example, through image recognition using dynamic detection.

[0007] Therefore, embodiments of the present invention provide a laminate with excellent design quality and capable of obtaining information by image recognition. Further, other embodiments of the present invention provide a method for selecting the laminate of the above embodiment. Still further, other embodiments of the present invention provide a method for manufacturing a recycled base material using the selection method of the above embodiment.

Means for Solving the Problems

[0008] The present invention relates to the following [1] to

[15] .

[0009] [1] A laminate including a base material, a near-infrared light transmissive visible light shielding layer, and a near-infrared light identifiable information layer.

[0010] [2] The laminate according to [1], wherein the base material includes any one of a polyolefin resin film, a polyester resin film, and a polyamide resin film.

[0011] [3] The laminate according to [1] or [2], wherein the total light transmittance of the base material measured in accordance with JIS K 7361-1 is 50% or more.

[0012] [4] The laminate according to any one of [1] to [3], wherein the thickness of the base material is 10 μm or more and 1000 μm or less.

[0013] [5] The laminate according to any one of [1] to [4], further having a near-infrared light reflection layer.

[0014] [6] The laminate according to [5], wherein the near-infrared light reflection layer contains aluminum.

[0015] [7] The laminate according to any one of [1] to [6], wherein the content of the near-infrared light absorbing material in the near-infrared light identifiable information layer is 10% by mass or less with respect to 100% by mass of the near-infrared light identifiable information layer. <000011l>

[0016] [8] The laminate according to any one of [1] to [7], wherein the near-infrared light identifiable information layer contains a white pigment and / or an aluminum pigment.

[0017] [9] A laminate according to any one of [1] to [8], wherein the near-infrared light transmitting visible light shielding layer contains a white pigment.

[0018]

[10] L of the near-infrared light transmitting visible light shielding layer * A laminate described in any of [1] to [9], with a value of 55 or greater.

[0019]

[11] The laminate according to any one of [1] to

[10] , wherein the mass ratio of the pigment contained in the near-infrared light discriminable information layer to the pigment contained in the near-infrared light transmitting visible light shielding layer is 0 / 100 to 200 / 100.

[0020]

[12] A laminate according to any of [1] to

[11] , for use as packaging material.

[0021] A method for identifying a laminate, comprising identifying near-infrared light-identifiable information contained in the near-infrared light-identifiable information layer of the laminate described in any of [1] to

[12] using near-infrared light.

[0022]

[14] A method for identifying a laminate according to

[13] , wherein the near-infrared light-identifiable information is information relating to the material of the laminate.

[0023]

[15] From among articles containing plastic substrates, An identification step of a laminate A described in any of [1] to

[12] , wherein the substrate is a plastic substrate and has specific near-infrared light identifiable information, using near-infrared light. After the identification step, a sorting step is performed to select the laminate A from the articles containing the plastic substrate. After the sorting step, a separation step is performed to separate the near-infrared light-transmitting visible light-shielding layer and the near-infrared light-identifiable information layer of the laminate A from the plastic substrate, and After the separation step, a recovery step is taken to recover the plastic substrate as a recycled substrate. A method for manufacturing recycled substrates, including the method described above. [Effects of the Invention]

[0024] According to embodiments of the present invention, it is possible to provide a laminate with excellent design quality and the ability to acquire information through image recognition. Furthermore, other embodiments of the present invention can provide a method for sorting laminates that can sort the laminates of the above embodiments, and a method for manufacturing recycled substrates using the sorting method. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic diagram showing the general configuration of a method for manufacturing recycled substrates, which is one embodiment of the present invention. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below. In some cases, a film packaging material (hereinafter sometimes abbreviated as "packaging material"), which is a typical form of the laminate of the present invention, will be used as an example for specific explanations. However, the present invention is not limited to the embodiments described below and includes various embodiments.

[0027] <Laminate> The laminate of the present invention comprises a substrate, a near-infrared light transmitting visible light shielding layer, and a near-infrared light identifiable information layer, and a near-infrared light reflecting layer may be provided between the substrate and the near-infrared light identifiable information layer.

[0028] The structure of the laminate will be described in more detail below. In one embodiment, the laminated structure of the laminate may be, for example, as follows. ·Base material / near infrared light identification information layer / near infrared light transmission visible light shielding layer ·Base material / Near infrared light reflective layer / Near infrared light distinguishable information layer / Near infrared light transmission visible light shielding layer / Colored layer ·Base material / Near infrared light transmission visible light shielding layer / Near infrared light identification information layer • Substrate / Near-infrared light transmitting visible light shielding layer / Near-infrared light identifiable information layer / Top coat layer ·Base material / Colored layer / Near infrared light transmission visible light shielding layer / Near infrared light identification information layer • Substrate / Near-infrared light identifiable information layer / Near-infrared light transmitting visible light shielding layer / Coloring layer / Heat seal layer / Substrate ·Base material / colored layer / near-infrared light transmission visible light shielding layer / near-infrared light identification information layer / adhesive layer / near-infrared light reflection layer / base material

[0029] The laminate of the present invention can be suitably used as packaging material for packaging bags, labels, lids, containers, etc., after undergoing processes such as slitting, die-cutting, molding, and sealing. The application of the laminate can be appropriately selected according to the quality of the laminate, and is not particularly limited to light packaging for snack foods, heavy bags for rice, labels for beverage bottles, lids, containers, etc. Retort sterilization and other treatments can also be appropriately performed according to the quality and application of the laminate.

[0030] <Base material> Examples of substrates used in the laminate of the present invention include plastic substrates, paper substrates, metal substrates, other substrates, or composite substrates thereof. In particular, laminates containing a plastic substrate have the use of recycling the plastic substrate into a recycled substrate, and are one of the most effective forms of the laminate of the present invention. Examples of plastic substrates include films of thermoplastic resins or thermosetting resins, with thermoplastic resin films being preferred. Examples of thermoplastic resins include polyolefins, polyesters, polyamides, polystyrenes, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, and cellulose-based plastics. The plastic substrate can be appropriately selected according to the application, such as a printed film with a near-infrared light transmitting visible light shielding layer, a near-infrared light identifiable information layer, a barrier film to protect the contents from oxygen and water, or a sealant film that seals the packaging material by heat or other means. It may be a single-layer structure or a multi-layer structure (laminated).

[0031] More specifically, the following can be used as base materials: polyester resin films such as polyethylene terephthalate, polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resin films such as polyethylene (PE) and polypropylene (PP); polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; and composites of these (e.g., nylon 6 / MXD6 / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6) or mixtures thereof. Among these, those with mechanical strength and / or dimensional stability are preferred. Furthermore, polyolefin resin films, polyester resin films, or polyamide resin films, which are widely used as packaging materials for printing substrates and sealant applications, are particularly preferred.

[0032] The total light transmittance of the substrate measured with a D65 light source in accordance with JIS K7361-1 is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. Printing, for example, white ink onto a transparent film with high total light transmittance to ensure opacity is a suitable practice from the standpoint of performance and cost of packaging materials, and a transparent film with high total light transmittance is a suitable substrate in the present invention, which uses a near-infrared light transmitting visible light shielding layer.

[0033] The thickness of the substrate is preferably 10 μm to 1000 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 50 μm. When the thickness of the substrate is within the above range, it becomes easier to separate the identified laminates and packaging materials. For example, in the case of air separation, which is commonly used in the field of plastic recycling, a thickness of 10 μm or more makes it less likely for surrounding film substrates to be blown around during separation, making separation easier. On the other hand, a thickness of 1000 μm or less allows the airflow during separation to be suppressed, and the speed can be kept above a certain level, resulting in good separation efficiency.

[0034] When laminating two or more substrates, the method is not particularly limited. For example, methods include laminating using a sealant such as a heat sealant, laminating the adhesive layer and the sealant film by heat (heat lamination, dry lamination), and laminating by melting the sealant resin, extruding it onto the adhesive layer, and allowing it to cool and solidify (extrusion lamination method). When laminating two or more substrates, it is preferable that they be made of the same material. If they are made of the same material, there is no need to treat the other substrates as impurities during recycling, and they can be handled as monomaterial packaging suitable for recycling, along with packaging using a single layer of substrate.

[0035] <Near-infrared light transmission visible light shielding layer> The near-infrared light-transmitting visible light-shielding layer is installed with the purpose of allowing the information in the near-infrared light-identifiable information layer to be identified, while preventing the information in the infrared light-identifiable information layer from being identified by visible light. In other words, the near-infrared light-transmitting visible light-shielding layer is a layer that transmits near-infrared light but blocks visible light. The near-infrared light-transmitting visible light-shielding layer may be laminated directly onto the substrate, or it may be laminated onto the substrate via the near-infrared light-identifiable information layer, the near-infrared light-reflecting layer, or other layers described later.

[0036] The near-infrared light-transmitting visible light shielding layer needs to transmit near-infrared light in order to allow the information in the near-infrared light-identifiable information layer to be identified, but it is preferable that it does not completely transmit near-infrared light due to reflection and scattering. When the near-infrared light-transmitting visible light shielding layer does not completely transmit the near-infrared light used for identification, the degree of scattering and reflection of near-infrared light by the near-infrared light-transmitting visible light shielding layer changes in the portion where the near-infrared light-identifiable information layer is stacked. This causes a change in the amount of light detected depending on the presence or absence of the near-infrared light-identifiable information layer, making the near-infrared light-identifiable information layer easier to identify. Therefore, the transmittance of the near-infrared light-transmitting visible light shielding layer with respect to the wavelength of near-infrared light used for identification is preferably 30% to 100%, more preferably 40% to 90%, and even more preferably 50% to 80%.

[0037] The near-infrared light-transmitting visible light-shielding layer preferably shields visible light as much as possible within the range in which the near-infrared light-identifiable information layer can be identified by near-infrared light, in order to prevent the near-infrared light-identifiable information layer from being visually identified. By shielding visible light, the near-infrared light-identifiable information layer does not impede the visibility of the information added as a design to the film packaging material, thus allowing the designer's intentions to be reflected. The visible light transmittance of the near-infrared light-transmitting visible light-shielding layer preferably has a total light transmittance of 80% or less, more preferably 70% or less, and particularly preferably 60% or less, as measured in accordance with JIS K 7361-1.

[0038] The near-infrared light transmitting visible light shielding layer preferably contains a white pigment. White pigments transmit near-infrared light while exhibiting excellent visible light shielding performance. Examples of white pigments include titanium dioxide, silica, calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, talc, and pearl pigments such as Merck's Iriodin. Among these, titanium dioxide has been suitably used in conventional film packaging materials in terms of safety, visible light shielding performance, and manufacturing cost, and can be suitably used in the laminate of the present invention.

[0039] In other words, a preferred form of the near-infrared light transmitting visible light shielding layer is a form in which the near-infrared light transmitting visible light shielding layer is a white ink layer. L of the near-infrared light transmitting visible light shielding layer * The value is preferably 55 or higher, and more preferably 65 or higher. * If the value is 55 or higher, the near-infrared light transmitting visible light shielding layer will appear almost white to the naked eye, and will not affect the coloring by the printing inks necessary for forming the design of the laminate, resulting in good design quality of the laminate. As a result, it becomes possible to provide a near-infrared light identifiable information layer over a larger area of ​​the laminate, making it easier to identify the laminate.

[0040] The near-infrared light transmitting visible light shielding layer may contain other components as long as it does not impair its performance. Typical examples of other components include colorants, binder resins, and additives. These components may be selected as appropriate depending on the design quality, composition, application, and required properties of the laminate.

[0041] Examples of colorants include inorganic pigments, organic pigments, dyes, and metallic pigments that provide a metallic luster. Examples of inorganic pigments include colored pigments such as red iron oxide, Prussian blue, ultramarine, carbon black, and graphite. Examples of organic pigments include those listed under the generic names of the color index, and suitable examples include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. Furthermore, the above-mentioned coloring agent and near-infrared light transmitting visible light shielding layer may contain a pigment derivative or a resin-type dispersant as a dispersant.

[0042] Examples of binder resins include nitrocellulose-based resins, fibrous materials such as cellulose acetate-propionate, chlorinated polypropylene-based resins, vinyl chloride-vinyl acetate copolymer-based resins, polyester-based resins, acrylic-based resins, urethane resin-based and acrylic urethane-based resins, polyamide-based resins, polybutyral-based resins, cyclocompound rubber-based resins, and chlorinated rubber-based resins. Among these, urethane resin-based, polyester resin-based, or chlorinated polypropylene resin-based binder resins are preferred. These resins may be used individually or in combination of two or more. In particular, when a plastic substrate is used and a near-infrared light transmitting visible light shielding layer is directly provided on the substrate, a binder resin based on urethane resin, polyester resin, or chlorinated polypropylene resin, which has excellent adhesion to the plastic substrate, is preferably used.

[0043] As additives, those conventionally used in printing inks and coatings may be used. Examples include curing agents and crosslinking agents to improve film formation and adhesion, waxes to improve film properties such as abrasion resistance and scratch resistance, leveling agents to improve wettability, and defoamers to suppress foaming during coating.

[0044] The amount of near-infrared light transmitting visible light shielding layer applied can be appropriately selected from the perspective of the printing method and visible light shielding performance. However, for example, when using gravure ink containing volatile organic solvents for coating, from the perspective of drying properties and shielding performance, the amount should be 0.3 to 3.0 g / m² in a dry state. 2 Preferably, it is 0.5 to 2.5 g / m 2 It is more preferable that the amount be 0.7-2.0 g / m 2 It is even more preferable that this be the case.

[0045] <Near-infrared light identification information layer> The near-infrared identifiable information layer is a layer that contains information identifiable by near-infrared light. For example, if the identifiable information is represented by shades of gray, the information can be imaged and extracted from the image data. Examples of such information include identification information for determining whether the film packaging material is recyclable, information about the material of the substrate, information about the recycling method of the substrate, and other product information, which may be desired for various purposes. The near-infrared identifiable information layer may be directly laminated onto the substrate, or it may be laminated onto the substrate via a near-infrared light transmitting visible light shielding layer, a near-infrared light reflecting layer, or other layers described later.

[0046] The above identification information is preferably dynamically detectable and preferably applied by printing. "Dynamic detection possible" means that the identification information can be extracted (read) by a reader when the packaging material is being transported, for example, by a belt conveyor belt. There are no particular restrictions on the shape or size of the identification information, and it may be appropriately selected depending on the accuracy of identification and the amount of identification information. For example, it may be in the form of a two-dimensional code, a barcode, or a QR code (registered trademark).

[0047] The above identification information may be placed on a part of the surface of the laminate or on the entire surface, and it is preferable that it be placed on the entire surface. By placing the identification information on the entire surface, the same information can be assigned to different locations. Therefore, for example, even if the packaging material is damaged or deformed, the identification information can be easily detected. Furthermore, even if the laminate is used as packaging material for wrapping small pieces of candy, for example, the assignment of identification information is easy.

[0048] When the near-infrared identifiable information layer contains a near-infrared light absorbing material, the content of the near-infrared light absorbing material in the near-infrared identifiable information layer is preferably 10% by mass or less, and more preferably 1% by mass or less, relative to 100% by mass of the near-infrared identifiable information layer. Here, the near-infrared light absorbing material is a material that has high visible light transmittance and absorbs near-infrared light, or carbon black that absorbs both visible light and near-infrared light. Examples of near-infrared light absorbing materials that have high visible light transmittance and absorb near-infrared light include inorganic near-infrared light absorbing materials such as ITO (indium tin oxide) and known organic near-infrared light absorbing materials. Inorganic near-infrared light absorbing materials other than carbon black and organic near-infrared light absorbing materials have little track record of use in film packaging materials and are expensive, so reducing the amount used is preferable in terms of safety and manufacturing cost. Furthermore, while carbon black is particularly suitable for use in film packaging materials, its strong visible light absorption performance and high visibility mean that if the near-infrared light-identifiable information layer contains carbon black, the near-infrared light-identifiable information layer may become visible, potentially degrading the design quality of the laminate. Therefore, it is preferable to reduce the amount used.

[0049] The near-infrared light-recognizable information layer preferably contains a white pigment and / or an aluminum pigment. Examples of white pigments include those described in the above-mentioned description of the near-infrared light-transmitting visible light-shielding layer. By including a white pigment in the near-infrared light-recognizable information layer, it becomes difficult to visually determine the presence or absence of the near-infrared light-recognizable information layer when laminated with the near-infrared light-transmitting visible light-shielding layer, thereby maintaining the design quality of the laminate incorporating the near-infrared light-transmitting visible light-shielding layer and the near-infrared light-recognizable information layer. Furthermore, including an aluminum pigment in the near-infrared light-recognizable information layer can improve its recognition ability. The amount of aluminum pigment can be appropriately adjusted depending on the composition and thickness of the near-infrared light-recognizable information layer, the structure of the laminate, the recognition accuracy, and the design quality.

[0050] Examples of the above-mentioned aluminum pigments include aluminum pastes such as Alpaste and Chromashine from Toyo Aluminum Co., Ltd., and Rotovario from Ekart Co., Ltd. These aluminum pigments may be used individually or mixed together in combination of two or more types.

[0051] To maintain good design quality of the laminate, the color difference ΔE of the laminate with or without the near-infrared light-distinguishable information layer is preferably 3 or less, and more preferably 2 or less. A smaller ΔE makes it difficult to visually distinguish the presence or absence of the near-infrared light-distinguishable information layer of the laminate with the naked eye, thus maintaining good design quality of the laminate. The color difference can be measured from the side that the end user will see, depending on the application of the laminate. The coated side, where the near-infrared light-transmitting visible light-shielding layer or the near-infrared identifiable information layer is applied, or the uncoated side, which is visible through the substrate, can be appropriately selected for measurement.

[0052] The mass ratio of the pigment contained in the near-infrared light-distinguishable information layer to the pigment contained in the near-infrared light-transmitting visible light-shielding layer is preferably 0 / 100 to 200 / 100. Having this mass ratio within this range allows for a reduced visibility of the near-infrared light-distinguishable information layer relative to the visible light-shielding performance of the near-infrared light-transmitting visible light-shielding layer. This reduces the color difference between the laminate with and without the near-infrared light-distinguishable information layer, thus maintaining good design quality for the laminate.

[0053] The near-infrared light-identifiable information layer, like the near-infrared light-transmitting visible light-shielding layer, may also contain other components as long as their performance is not impaired, and can be appropriately selected depending on the design quality, configuration, and application of the laminate.

[0054] The coating amount of the near-infrared light-identifiable information layer can be appropriately selected from the viewpoints of printing method and identification performance, similar to the near-infrared light-transmitting visible light-shielding layer. For example, when using gravure ink containing a volatile organic solvent for coating, from the viewpoints of drying property, identification performance, and concealment by the near-infrared light-transmitting visible light-shielding layer, in the dry state, it is preferably 0.05 to 3.0 g / m 2 and more preferably 0.1 to 2.5 g / m 2 and still more preferably 0.2 to 2.0 g / m 2 is even more preferable.

[0055] <Near-infrared light reflection layer> The laminate of the present invention preferably further includes a near-infrared light reflection layer. By including a near-infrared light reflection layer in the laminate, when identifying the near-infrared light-identifiable information layer with near-infrared light, the incident near-infrared light is reflected, thereby improving the identifiability. When performing identification from the printing layer side, the near-infrared light reflection layer is preferably located between the substrate and the near-infrared light-identifiable information layer. Examples of the near-infrared light reflection layer include a metal foil, a metal vapor deposition layer, a printing layer containing a metal pigment, etc. In order to provide a near-infrared light reflection layer to the laminate, a material in which the substrate and the near-infrared light reflection layer are laminated in advance may be used.

[0056] The near-infrared light reflection layer more preferably contains aluminum. Examples of the near-infrared light reflection layer containing aluminum include an aluminum foil, a vapor-deposited aluminum layer, a printing ink layer containing an aluminum pigment, etc., and are not particularly limited. The aluminum foil, the vapor-deposited aluminum layer, and the printing ink layer containing an aluminum pigment have all been conventionally used for film packaging materials, and can also be suitably used for the laminate of the present invention from the viewpoints of safety and manufacturing cost. In addition, the aluminum foil or the vapor-deposited aluminum layer can also function as a barrier layer. Also, in the case of a laminate having a substrate on one surface of the near-infrared light reflection layer containing aluminum and having layers such as a near-infrared light-transmitting visible light-shielding layer and a near-infrared light-identifiable information layer on the other surface, the near-infrared light reflection layer can be dissolved by immersing it in an alkaline aqueous solution, and the layers such as the near-infrared light-transmitting visible light-shielding layer and the near-infrared light-identifiable information layer and the substrate can be separated. The separated substrate can be recovered as a high-purity substrate after washing.

[0057] <Other layers> The laminate of the present invention may further contain other layers to impart functionality as a laminate. Examples of other layers include a coloring layer for forming a design, an adhesive layer or heat-sealing layer for bonding to different substrates, and a topcoat layer for protecting the surface of the laminate or changing its surface gloss to provide aesthetic appeal. These layers may be formed simultaneously with the near-infrared light-identifiable information layer and the near-infrared light-transmitting visible light-shielding layer by printing or coating using the same printing or coating method, or they may be formed using different printing or coating methods. These other layers may be contained in the laminate individually or in pairs or more, and can be used in any order with respect to the substrate, the near-infrared light-identifiable information layer, and the near-infrared light-transmitting visible light-shielding layer.

[0058] By making one or more of the near-infrared light-identifiable information layer, the near-infrared light-transmitting visible light-shielding layer, and other layers react with a desorption solution, it becomes possible to separate the layers with the desorption solution after sorting and recovering the laminate, thereby recovering a high-purity plastic substrate. For example, each layer can be formed using a material that swells or dissolves in an alkaline aqueous solution using a known method, and each layer can be separated from the substrate by using an alkaline aqueous solution as the desorption solution. Furthermore, the separated substrate can be recovered as a high-purity substrate after washing and recycled.

[0059] <Method for identifying laminated structures> The present invention provides a method for identifying a laminate using near-infrared light. In this identification method, near-infrared light-identifiable information contained in the near-infrared light-identifiable information layer is identified using near-infrared light. Preferably, the near-infrared light-identifiable information is information about the material of the laminate.

[0060] Identification using near-infrared light is preferably performed using image processing technology with an imaging device such as a near-infrared camera. For example, one method involves using an imaging device, a control device that extracts identification information from image data of the packaging material captured by the imaging device and determines whether sorting is necessary based on the extracted identification information, and a sorting device that sorts the packaging material based on the determination.

[0061] Near-infrared light refers to light rays with wavelengths of approximately 800 nm to 2500 nm. In particular, commercially available near-infrared cameras often have imaging wavelengths of approximately 950 nm to 1700 nm, and in the identification of laminates according to the present invention, it is preferable to use a camera capable of detecting these wavelengths for imaging and identification. Representative examples of near-infrared cameras that are on the market include the InGaAs line scan camera manufactured by Hamamatsu Photonics and the Wave series manufactured by JAI Corporation, and these cameras can be used for inline inspection by dynamic detection.

[0062] <Method for manufacturing recycled substrates> When the laminate of the present invention includes a plastic substrate, it is possible to use the laminate to provide a method for producing a recycled substrate based on a mixture of articles containing a plastic substrate, such as waste plastic. The manufacturing method includes an identification step of identifying a laminate A of the present invention, in which the substrate is a plastic substrate and has specific near-infrared light-identifiable information, from among articles containing a plastic substrate using near-infrared light; a selection step of separating the laminate A from the articles containing the plastic substrate after the identification step; a separation step of separating the near-infrared light-transmitting visible light-shielding layer and the near-infrared light-identifiable information layer of the laminate A from the plastic substrate after the selection step; and a recovery step of recovering the plastic substrate as a recycled substrate after the separation step.

[0063] [Identification process] The identification method in the identification step is preferably the form described in the explanation of the identification method for the laminate described above.

[0064] [Sorting process] As for the sorting method in the sorting process, known methods for sorting plastic substrates can be used. For example, the laminates identified through the conveyor can be moved to another conveyor using human power, a robotic arm, an air gun, etc., and collected at the conveyor exit.

[0065] [Separation and Recovery Processes] Since the laminate of the present invention includes coating layers such as a near-infrared light-identifiable information layer and a near-infrared light-transmitting visible light-shielding layer, it is desirable to separate these coating layers from the plastic substrate and then recover the plastic substrate as a recycled substrate. There are no particular limitations on the method of separation, and examples include washing the laminate with a solvent such as an alkaline aqueous solution that can dissolve the coating layers and removing the peeled coating layers from the plastic substrate by size separation or specific gravity separation, or dissolving the laminate in a heated solvent that dissolves only the plastic substrate, separating the plastic substrate solution from the coating layers, cooling the solution and recovering the recycled substrate as a precipitate.

[0066] The method for manufacturing recycled substrates will be described in more detail below with reference to the drawings. Figure 1 is a schematic diagram showing the general configuration of a method for manufacturing recycled substrates, which is one embodiment of the present invention. In this embodiment, packaging materials 100a, 100b, and 100c are assumed, in which recycling identification information is provided on a substrate including a plastic film by a near-infrared light-identifiable information layer.

[0067] After being used by consumers, packaging materials are collected by local governments or businesses and gathered at designated collection points. These collection points may be suitable facilities such as warehouses. As shown in Figure 1, the packaging materials collected at the collection point are transported to the sorting device 300b by an appropriate conveying device such as a belt conveyor. The sorting device 300b may be located in the same facility as the collection point. The packaging materials being transported by the conveying device are individually imaged by an appropriate imaging device 300a such as a near-infrared camera.

[0068] The appearance of the packaging material acquired by the imaging device is sent to the control device as image data. The control device has an identification information extraction unit that extracts image data of identification information related to sorting and recycling from the image data of the packaging material's appearance, and extracts the identification information from the image data of the identification information. It also has a discrimination unit that identifies the packaging material to be identified according to the content of the extracted identification information. The control device may be configured, for example, by a personal computer.

[0069] The sorting device 300b sorts each packaging material sent by the conveying device according to instructions from the control device. When identification information for the packaging material is extracted and it is determined to be a target packaging material for sorting and recycling, the packaging material is routed to the recycling route. If the identification information for the packaging material contains information about the constituent materials of the base material or an appropriate recycling method, the route may be further routed according to the identification information. On the other hand, if the packaging material does not have identification information, or if it is determined to be unrecyclable based on the identification information, it may be routed to a different route from the route for recycling the base material.

[0070] As an example, Figure 1 shows that the materials are divided into a first route leading to a first sorting location for collecting packaging material 100a, a second route leading to a second sorting location for collecting packaging material 100b, and a third route leading to a third sorting location for collecting packaging material 100c. The first to third routes may each be composed of a belt conveyor. The first to third sorting locations may differ depending on the recycling method. For example, as shown in Figure 1, the first and second sorting locations may sort the collected materials to be recycled, while the third sorting location may sort the packaging materials that will not be recycled. The first to third sorting locations may be located in the same facility as the collection area. [Examples]

[0071] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, "parts" and "%" refer to "parts by mass" and "mass%" unless otherwise noted.

[0072] The molecular weight, molecular weight distribution, acid value, and hydroxyl value of the synthesized polyurethane resin varnish A1 and polyester polyols P1 and P2 are shown below. <Molecular weight and molecular weight distribution> The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were measured by GPC (gel permeation chromatography) and determined as converted molecular weights using polystyrene as a standard substance. The measurement conditions are shown below. GPC device: Showa Denko Shodex GPC-104 Columns: The following columns were used, connected in series. Two Shodex LF-404 tubes manufactured by Showa Denko. Showa Denko Shodex LF-G Detector: RI (Differential Refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 0.3mL / min

[0073] <Acid value, hydroxyl value> Acid value and hydroxyl value were measured in accordance with JIS K 0070 (1992).

[0074] <Total light transmittance> The total light transmittance of the substrate was measured using a D65 light source in accordance with JIS K7361-1. The total light transmittance of VMCPP was measured after washing the substrate with a 2% sodium hydroxide aqueous solution and removing the vapor-deposited aluminum layer.

[0075] (Synthesis of polyurethane resin varnish A1 for near-infrared light discriminable information layer and near-infrared light transmitting visible light shielding layer) In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 136.3 parts of PPA (poly(propylene glycol) adipate diol) with a number average molecular weight (hereinafter referred to as Mn) of 2000, 13.6 parts of PPG (polypropylene glycol) with a number average molecular weight (hereinafter referred to as Mn) of 2000, 25.0 parts of DMPA (2,2-dimethylolpropanoic acid), 3.9 parts of NPG (neopentyl glycol), 88.7 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (n-propyl acetate) were charged. The mixture was reacted under a nitrogen stream at 90°C for 3 hours to obtain a solution of terminal isocyanate prepolymer. Next, the obtained terminal isocyanate prepolymer was gradually added at room temperature to a mixture of 16.9 parts AEA (2-(2-aminoethylamino)ethanol), 0.2 parts MEA (monoethanolamine), and 350 parts IPA (isopropyl alcohol), and the mixture was then reacted at 50°C for 1 hour. After that, 1.3 parts IPDI was added to adjust the amine value to 5.0 mg KOH / g, and then 4.0 parts of phthalic anhydride in an equivalent amount to the amino group was added and the mixture was reacted at 50°C for 1 hour. 150 parts NPAC was added to the resulting resin solution to adjust the solid content, yielding polyurethane resin varnish A1 with a solid content of 30% by mass, a weight-average molecular weight of 28000, Mw / Mn = 3.2, an acid value of 45.0 mg KOH / g, and a hydroxyl value of 30.8 mg KOH / g.

[0076] (Manufacturing of laminate adhesive T1) A polyurethane-based adhesive described in Japanese Patent Publication No. 2021-088184 was used as the laminate adhesive T1. Specifically, 90 parts of a solution of polyester polyol (P1), 10 parts of a solution of polyester polyol (P2), and 8 parts of a solution of polyisocyanate (C1) were mixed, and ethyl acetate was added to prepare adhesive T1 with a non-volatile content of 30%.

[0077] Synthesis of polyester polyol P1 In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 124 parts of ethylene glycol, 212 parts of neopentyl glycol, 368 parts of 1,6-hexanediol, 645 parts of isophthalic acid, 36 parts of adipic acid, and 265 parts of sebacic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the predetermined amount of water was distilled off and the acid value was reduced to 5 or less, the reaction was continued, and the pressure was gradually reduced to 1 mmHg or less for a deglycolization reaction to obtain a polyester polyol. Subsequently, 35 parts of isophorone diisocyanate were gradually added, and the reaction was carried out at 150°C for about 2 hours to obtain a polyester polyurethane polyol. 12.0 parts of ethylene glycol bisanhydrotrimellitate were added to 100 parts of this polyester polyurethane polyol, and the mixture was reacted at 180°C for approximately 2 hours. The mixture was then diluted with ethyl acetate until the non-volatile content reached 50%, thereby obtaining a solution of partially acid-modified polyester polyol P1 with a number average molecular weight of 9,000 and an acid value of 30.3 mg KOH / g.

[0078] Synthesis of polyester polyol P2 In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet, 58 parts ethylene glycol, 412 parts diethylene glycol, 343 parts neopentyl glycol, 517 parts isophthalic acid, and 393 parts adipic acid were charged. The mixture was heated to 250°C while stirring under a nitrogen stream, and the esterification reaction was carried out. After the reaction continued until a predetermined amount of water was distilled off and the acid value was 5 or less, the pressure was gradually reduced, and a deglycolization reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. 4.0 parts trimellitic anhydride was added to 100 parts of this polyester polyol, and the mixture was reacted at 180°C for about 2 hours. After that, it was diluted with ethyl acetate until the non-volatile content was 50%, to obtain a solution of partially acid-modified polyester polyol P2 with a number average molecular weight of 2,000 and an acid value of 23.5 mg KOH / g.

[0079] Preparation of Polyisocyanate C1 Coronate 2785 (a biuret-type polyisocyanate derived from hexamethylene diisocyanate, manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the non-volatile content to 50% and NCO% to 9.6% to obtain a solution of polyisocyanate C1.

[0080] Preparation of vinyl chloride-vinyl acetate copolymer resin varnish L1 70 parts of a methyl ethyl ketone / ethyl acetate = 70 / 30 mixed solvent were placed in a three-necked flask, and while heated to 60°C, 30 parts of vinyl chloride-vinyl acetate copolymer resin (Solvine TAO, manufactured by Nisshin Chemical Co., Ltd.) were gradually added. The mixture was then stirred and mixed in a disperser for 30 minutes to obtain vinyl chloride-vinyl acetate copolymer resin varnish L1.

[0081] Preparation of Titanium Dioxide Dispersion M1 20 parts of polyurethane resin varnish A1, 20 parts of vinyl chloride-vinyl acetate copolymer resin varnish L1, 28 parts of titanium dioxide pigment (Titanics JR-800, manufactured by Teika Co., Ltd.), and 32 parts of a mixed solvent of n-propyl acetate / isopropyl alcohol = 70 / 30 (mass ratio) were stirred and mixed in a disperser for 30 minutes, and then dispersed using a sand mill for 20 minutes to obtain titanium dioxide dispersion M1.

[0082] Preparation of carbon black dispersion N1 20 parts of polyurethane resin varnish A1, 20 parts of vinyl chloride-vinyl acetate copolymer resin varnish L1, 20 parts of carbon black pigment (Mitsubishi Carbon #85, manufactured by Mitsubishi Chemical Corporation), and 40 parts of a mixed solvent of n-propyl acetate / isopropyl alcohol = 70 / 30 (mass ratio) were stirred and mixed in a disperser for 30 minutes, and then dispersed using a sand mill for 20 minutes to obtain carbon black dispersion N1.

[0083] Preparation of Printing Ink X1 for Near-Infrared Light Transmitting and Visible Light Shielding Layer Fifty parts of titanium dioxide dispersion M1 and fifty parts of a mixed solvent of n-propyl acetate / isopropyl alcohol = 70 / 30 were mixed and stirred in a disperser for 30 minutes to obtain printing ink X1 for near-infrared light transmitting and visible light shielding layer.

[0084] Preparation of Printing Ink Y1 for Near-Infrared Light-Recognizable Information Layer 45 parts of polyurethane resin varnish A1, 5 parts of vinyl chloride-vinyl acetate copolymer resin varnish L1, and 50 parts of a mixed solvent of n-propyl acetate / isopropyl alcohol = 70 / 30 were stirred and mixed in a disperser for 30 minutes to obtain printing ink Y1 for near-infrared light discriminable information layer.

[0085] Preparation of Printing Inks Y2-Y9 for Near-Infrared Light Identifiable Information Layer Printing inks Y2 to Y9 for the near-infrared light-recognizable information layer were obtained using the same method as for Y1, following the formulation examples in Table 1.

[0086] [Table 1]

[0087] The details of the materials listed in Table 1 are as follows: Pearl pigment: Merck's Iriodin 100 (natural mica particles coated with titanium dioxide) Aluminum paste pigment: Alpaste TD-S2172PA manufactured by Toyo Aluminum Co., Ltd.

[0088] Preparation of Printing Ink Z1 for Near-Infrared Light Reflecting Layer 20 parts of aluminum paste pigment (Alpaste TD-S2172PA, manufactured by Toyo Aluminum Co., Ltd.), 20 parts of polyurethane resin varnish A1, 20 parts of vinyl chloride-vinyl acetate copolymer resin varnish L1, and 40 parts of a mixed solvent of n-propyl acetate / isopropyl alcohol = 70 / 30 were mixed and stirred in a disperser for 30 minutes to obtain printing ink Z1 for near-infrared light reflective layer.

[0089] <Manufacturing of laminates> [Example 1] (Laminate H1) On OPP (biaxially oriented polypropylene, FOR manufactured by Futamura Chemical Co., Ltd., 20 μm thick, total light transmittance 92%), a printing ink X1 for a near-infrared light transmitting visible light shielding layer was printed using a gravure printing press equipped with a gravure cylinder of type E1 (Helio 175 lines / inch stylus 130° compressed plate type) to a thickness of 1 μm after drying, and dried at 70°C. Furthermore, a printing ink Y1 for a near-infrared light identifiable information layer was printed on the near-infrared light transmitting visible light shielding layer using a gravure printing press equipped with a gravure cylinder with a character pattern formed to a depth of 10 μm, and dried at 70°C, resulting in a printed material consisting of a substrate layer (OPP) / near-infrared light transmitting visible light shielding layer (X1) / near-infrared light identifiable information layer (Y1). Next, a laminating adhesive T1 was applied to the near-infrared light-distinguishable information layer of the printed material to a thickness of 3 μm using a bar coater and dried. Then, it was laminated with the vapor-deposited aluminum layer of a vapor-deposited aluminum-CPP laminate film (VMCPP2203, manufactured by Toray Film Processing Co., Ltd., 25 μm thick, CPP total light transmittance 91%) using a small desktop test laminator (manufactured by Tester Sangyo Co., Ltd.). The resulting laminate was aged at 40°C for 24 hours to obtain a laminate H1 consisting of a base layer (OPP) / near-infrared light-transmitting visible light-shielding layer (X1) / near-infrared light-distinguishable information layer (Y1) / laminating adhesive layer (T1) / near-infrared light-reflecting layer (vapor-deposited aluminum) / base layer (CPP).

[0090] [Examples 2-11, Comparative Examples 1-2] (Laminates H2-H11, Comparative Laminates HH1-HH2) Laminates H2 to H11 and comparative laminates HH1 to HH2 were obtained in the same manner as in the production of laminate H1, except that the materials and printing methods were changed as shown in Tables 2 and 3. In Example 2, CPP (unoriented polypropylene, FHK2, manufactured by Futamura Chemical Co., Ltd., 50 μm thick, total light transmittance 88%) was used instead of the vapor-deposited aluminum-CPP laminate film. The printing plate for printing the printing ink for the near-infrared light transmitting visible light shielding layer is shown in Table 4.

[0091] [Example 12] (Laminate H12) On OPP (biaxially oriented polypropylene, FOR manufactured by Futamura Chemical Co., Ltd., 20 μm thick, total light transmittance 92%), printing ink Y2 for a near-infrared light-identifiable information layer was printed using a gravure printing press equipped with a gravure cylinder with a character pattern formed to a depth of 15 μm, and dried at 70°C. Furthermore, printing ink X1 for a near-infrared light-transmitting visible light-shielding layer was printed on the near-infrared light-identifiable information layer using a gravure printing press equipped with a gravure cylinder of type E1 to a thickness of 1 μm after drying, and dried at 70°C to obtain a laminate H12 consisting of a substrate layer (OPP) / near-infrared light-identifiable information layer (Y1) / near-infrared light-transmitting visible light-shielding layer (X1).

[0092] [Example 13] (Laminate H13) A CPP (unoriented polypropylene, Futamura Chemical Co., Ltd., FHK2, 50 μm thick, total light transmittance 88%) was coated with a laminating adhesive T1 to a thickness of 3 μm using a bar coater and dried. Then, using a small desktop test laminator (Tester Industries Co., Ltd.), the matte surface of an aluminum foil (soft aluminum foil, Toyo Aluminum Co., Ltd., 20 μm thick), which would serve as the near-infrared light reflective layer, was laminated to obtain a CPP / aluminum foil laminate. The glossy aluminum foil surface of the obtained laminate was printed with a printing ink Y1 for a near-infrared light identifiable information layer using a gravure printing machine equipped with a gravure cylinder that had a character pattern formed to a depth of 10 μm, and dried at 70°C. Furthermore, the printing ink Y1 for the near-infrared light-recognizable information layer was printed using a gravure printing press equipped with a gravure cylinder on which a character pattern was formed to a depth of 10 μm, and dried at 70°C to obtain a laminate H13 consisting of a substrate layer (CPP) / near-infrared light-reflecting layer (aluminum foil) / near-infrared light-recognizable information layer (Y1) / near-infrared light-transmitting visible light-shielding layer (X1).

[0093] [Example 14] (Laminate H14) On OPP (biaxially oriented polypropylene, FOR manufactured by Futamura Chemical Co., Ltd., 20 μm thick, total light transmittance 92%), printing ink Z1 for the near-infrared light reflective layer was printed using a gravure printing press equipped with a Helio 175 line / inch stylus 130° compressed plate gravure cylinder to a thickness of 1 μm after drying, and dried at 70°C. Next, printing ink Y2 for the near-infrared light identifiable information layer was printed on the near-infrared light reflective layer using a gravure printing press equipped with a gravure cylinder with a character pattern formed to a depth of 15 μm, and dried at 70°C. Furthermore, a printing ink X1 for a near-infrared light-transmitting visible light-shielding layer was printed onto the near-infrared light-identifiable information layer using a gravure printing machine equipped with a gravure cylinder of type E1 (Helio 175 lines / inch stylus 130° compressed plate type) to a thickness of 1 μm after drying, and dried at 70°C to obtain a laminate H14 consisting of a substrate layer (OPP) / near-infrared light-reflecting layer (Z1) / near-infrared light-identifiable information layer (Y2) / near-infrared light-transmitting visible light-shielding layer (X1).

[0094] <Rating> The following evaluations were conducted regarding the whiteness and color difference, which are indicators of the design quality of the laminate, as well as the near-infrared light identifiability of the laminate.

[0095] [Whiteness] In the laminate, at the portion where only a near-infrared light transmitting visible light shielding layer is laminated on the plastic substrate, the whiteness L was measured using X-Rite530 from the non-printed side in Examples 1-11 and from the printed side in Examples 12-14. * The value was measured. (Evaluation Criteria) A(Excellent):L * Value 75 or higher B(Good):L * Value of 65 or higher C(possible):L * Value of 55 or higher D (not allowed):L * The value is less than 55.

[0096] [Color difference] In the laminate, at the location where a near-infrared light-transmitting visible light-shielding layer is laminated on the plastic substrate (in the example; in the comparative example, at the location with the near-infrared light-identifiable information layer), the L values ​​were measured from the non-printed side in Examples 1-11 and Comparative Examples 1-2, and from the printed side in Examples 12-14, depending on the presence or absence of the near-infrared light-identifiable information layer. * value, a * value, b * The values ​​were measured using X-Rite530. The values ​​when a near-infrared light discriminable information layer is present are (L * x a * x , b * x ), the value when there is no near-infrared light discriminable information layer is (L * y a * y , b * y The color difference ΔE was calculated using the following formula. (Formula)ΔE=((L * x -L * y ) 2 +(a * x -a * y ) 2 +(b * x ―b * y ) 2 ) 1 / 2 (Evaluation Criteria) A (Excellent): ΔE value is less than 2.0 B (Good): ΔE value is 2.0 or greater, and less than 3.0. C (acceptable): ΔE value is 3.0 or greater, and less than 5.0. D (Not acceptable): ΔE value is 5.0 or higher

[0097] [Identifiability] In Examples 1-11 and Comparative Examples 1-2, the laminate was imaged from the non-printed side using a Hamamatsu Photonics C15333-10E04 near-infrared camera, and in Examples 12-14, from the printed side. The legibility of characters in the near-infrared identifiable information layer was evaluated. The imaging wavelengths are as shown in Tables 2 and 3. (Evaluation Criteria) A (Excellent): Characters in the near-infrared light-recognizable information layer can be easily identified. B (Good): The characters in the near-infrared light-recognizable information layer are faintly visible and can be read. C (Good): The presence of characters in the near-infrared light-recognizable information layer can be faintly confirmed, but the characters are difficult to read. D (Not possible): The presence of characters in the near-infrared light-recognizable information layer cannot be confirmed.

[0098] [Table 2]

[0099] [Table 3]

[0100] [Table 4]

[0101] The evaluation results above demonstrate that, according to the embodiment of the present invention, a laminate can be obtained in which the near-infrared light-identifiable information layer can be identified by a near-infrared light camera. Furthermore, because the laminate of the embodiment of the present invention has high whiteness and a small color difference with and without the near-infrared light-identifiable information layer, it is possible to form a design using a colored layer, and a laminate with good design quality can be obtained. [Explanation of symbols]

[0102] 100 Recyclable Packaging Materials 100a, 100b (Packaging materials determined to be recyclable) 100c (Packaging materials deemed unsuitable for recycling) 300a Imaging device 300b sorting device

Claims

1. A laminate comprising a substrate, a near-infrared light-transmitting visible light-shielding layer, and a near-infrared light-identifiable information layer.

2. The laminate according to claim 1, wherein the base material comprises any one of a polyolefin resin film, a polyester resin film, and a polyamide resin film.

3. The laminate according to claim 1, wherein the total light transmittance of the substrate, measured in accordance with JIS K 7361-1, is 50% or more.

4. The laminate according to claim 1, wherein the thickness of the substrate is 10 μm or more and 1000 μm or less.

5. The laminate according to claim 1, further comprising a near-infrared light reflective layer.

6. The laminate according to claim 5, wherein the near-infrared light reflective layer contains aluminum.

7. The laminate according to claim 1, wherein the content of the near-infrared light absorbing material in the near-infrared light discriminable information layer is 10% by mass or less with respect to 100% by mass of the near-infrared light discriminable information layer.

8. The laminate according to claim 1, wherein the near-infrared light-recognizable information layer comprises a white pigment and / or an aluminum pigment.

9. The laminate according to claim 1, wherein the near-infrared light transmitting visible light shielding layer contains a white pigment.

10. L, a near-infrared light transmitting and visible light shielding layer ＊ The laminate according to claim 1, wherein the value is 55 or greater.

11. The laminate according to claim 1, wherein the mass ratio of the pigment contained in the near-infrared light discriminable information layer to the pigment contained in the near-infrared light transmitting visible light shielding layer is 0 / 100 to 200 / 100.

12. A laminate according to claim 1, for use as a packaging material.

13. A method for identifying a laminate, comprising identifying near-infrared light-identifiable information contained in a near-infrared light-identifiable information layer in a laminate according to any one of claims 1 to 12 using near-infrared light.

14. The method for identifying a laminate according to claim 13, wherein the near-infrared light-identifiable information is information relating to the material of the laminate.

15. From among articles containing plastic substrates, An identification step for identifying a laminate A according to any one of claims 1 to 12, wherein the substrate is a plastic substrate and has specific near-infrared light identifiable information, using near-infrared light. After the identification step, a sorting step is performed to select the laminate A from among the articles containing the plastic substrate. After the sorting step, a separation step is performed to separate the near-infrared light-transmitting visible light-shielding layer and the near-infrared light-identifiable information layer of the laminate A from the plastic substrate, and After the separation step, a recovery step is taken to recover the plastic substrate as a recycled substrate. A method for manufacturing recycled substrates, including the method described above.

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