Recycled polyester molded product, and method for identifying and using the same.

Abstract

To provide a recycled polyester molded product that is highly versatile and can suppress quality degradation even if it contains identifying elements. [Solution] A recycled polyester molded article containing an element (A) selected from the group consisting of Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, Nb, Ca, Mn, S, Cr, Cu, Zn, and Co in an amount of 0.1 ppm by mass or more and 5000 ppm by mass or less.

Description

Technical Field

[0001] The present invention relates to recycled polyester molded articles, and a method for identifying and using the same.

Background Art

[0002] Conventionally, waste plastics have been treated by landfill, ocean dumping, incineration, etc. However, it is becoming difficult to secure landfill sites, and ocean dumping has become a problem environmentally because plastics do not decompose. Furthermore, although it can be used as heat by incineration, there is a problem that it leads to global warming due to the emission of carbon dioxide gas. Therefore, due to the recent increase in environmental problems, recycling of waste plastics such as reuse and regeneration is required, and research and development for this purpose are being actively carried out. In addition, since many plastics are produced from fossil fuels, the construction of a recycling method is also required from the viewpoint of effective use of resources.

[0003] Polyester, which is a type of plastic, has excellent properties such as heat resistance, weather resistance, mechanical strength, transparency, chemical resistance, and gas barrier properties, and is also easily available in terms of price. Therefore, it has high versatility and is currently a widely used resin for beverage and food containers, packaging materials, molded articles, films, etc. Among them, polyester films are light, inexpensive, and have high molding processability. Therefore, they are widely used in large quantities for various applications such as packaging, electronic parts, electrical insulation, metal laminates, display components such as flexible displays, touch panels, antireflection, and prevention of glass scattering. Therefore, the establishment of a recycling method and the stabilization of quality are required for polyester films.

[0004] To stabilize the quality of recycled products, for example, it is conceivable to certify or identify the recovered polyester film. For example, Patent Document 1 discloses a polyester film containing an inorganic compound as an identification compound at a concentration of 1 to 500 ppm by weight relative to dimethyl terephthalate. The inorganic compound is shown to be at least one precious metal selected from the group consisting of ruthenium, rhodium, palladium, silver, osnium, iridium, platinum, and gold.

[0005] Furthermore, Patent Document 2 discloses a transparent polymer comprising a polymer and 50 to 300 ppm of an XRF-identifiable marker, and in one embodiment, the XRF-identifiable marker is disclosed to include an atom selected from Co, Cu, Na, K, Zn, Ca, Mn, and Ti. Patent Document 2 states that by using these specific atoms, the optical properties are not substantially degraded by the XRF-identifiable marker. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-173585 [Patent Document 2] Special Publication No. 2019-520572 [Overview of the project] [Problems that the invention aims to solve]

[0007] For recycling to be established, it is desirable that the identification compounds and XRF identifiable markers used in Patent Documents 1 and 2 utilize elements with high general applicability. However, the precious metals exemplified in Patent Document 1 are rare, making it difficult to establish recycling using the technology disclosed in Patent Document 1.

[0008] Furthermore, polyester molded products such as polyester films are often coated on their surfaces in practical use, and they can also deteriorate through hydrolysis under certain conditions. Therefore, identification compounds and XRF-identifiable markers used for polyester molded products such as polyester films are desirable to be chemically stable with respect to polyester and do not inhibit the coating process. However, Patent Document 2 does not consider polyester molded products, nor does it show any XRF-identifiable markers suitable for polyester molded products.

[0009] Therefore, the object of the present invention is to provide a recycled polyester molded product that is highly versatile and can suppress quality deterioration even if it contains identifying elements. [Means for solving the problem]

[0010] As a result of diligent research, the inventors of the present invention have found that the above problems can be solved by incorporating specific elements in specific amounts into recycled polyester molded articles, and have completed the present invention as follows. The gist of the present invention is as follows [1] to

[23] .

[0011] [1] A recycled polyester molded article containing at least one element (A) selected from the group consisting of Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, Nb, Ca, Mn, S, Cr, Cu, Zn, and Co in an amount of 0.1 ppm by mass or more and 5000 ppm by mass or less. [2] A film made from recycled polyester as described in [1] above. [3] The recycled polyester molded article according to [1] or [2] above, wherein element (A) comprises at least one selected from the group consisting of Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb. [4] The recycled polyester molded article according to any one of [1] to [3] above, wherein the element (A) comprises at least one selected from the group consisting of Al, Mg, Ge, and Sc. [5] A recycled polyester molded product according to any of [1] to [4] above, wherein element (A) consists of two or more elements. [6] The recycled polyester molded article according to any one of [1] to [5] above, wherein the element (A) comprises at least one element (A1) selected from the group consisting of Al, Mg, Ge, and Sc, and at least one element (A2) selected from the group consisting of Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb. [7] The recycled polyester molded article according to any one of [1] to [6] above, wherein the element (A) comprises at least one element (A1) selected from the group consisting of Al, Mg, Ge, and Sc, and at least one element (A3) selected from the group consisting of Ca, Mn, S, Cr, Cu, Zn, and Co. [8] The recycled polyester molded article according to any one of [1] to [7] above, wherein element (A) comprises at least one element (A2) selected from the group consisting of Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb, and at least one element (A3) selected from the group consisting of Ca, Mn, S, Cr, Cu, Zn, and Co. [9] A recycled polyester molded article according to any one of [1] to [8] above, comprising a metal element nanocomposite containing the element (A).

[10] A recycled polyester molded article according to any of [1] to [9] above, wherein the intrinsic viscosity of the polyester contained in the recycled polyester molded article is 0.5 dL / g or more and 0.7 dL / g or less.

[11] Volume resistivity is 1.0 × 10 7 Ω cm or more 1.0×10 9 A recycled polyester molded product as described in any of the above [1] to

[10] , having a density of Ω·cm or less.

[12] A recycled polyester molded article according to any of [1] to

[11] above, wherein the carboxyl group concentration is 25 eq / ton or more and 60 eq / ton or less.

[13] A recycled polyester molded article according to any of [1] to

[12] above, wherein the ester cyclic trimer content is 10,000 ppm by mass or less.

[14] A recycled polyester molded article according to any of [1] to

[13] above, wherein the content of diethylene glycol in the total diol components of the polyester contained in the recycled polyester molded article is 5 mol% or less.

[15] A multilayer film having an intermediate layer and surface layers on both sides of the intermediate layer, wherein the intermediate layer contains the element (A), the recycled polyester molded article according to any one of [1] to

[14] above.

[16] A recycled polyester molded product according to any of the above [1] to

[15] , which is a biaxially oriented film.

[17] A recycled polyester molded article according to any of [1] to

[16] above, wherein the element (A) is detectable by X-ray fluorescence analysis (XRF).

[18] A method for identifying a recycled polyester molded product, comprising analyzing a recycled polyester molded product described in any of [1] to

[17] above, and identifying the recycled polyester molded product based on the type of element (A) detected in the recycled polyester molded product.

[19] A method for identifying a recycled polyester molded product, comprising analyzing a recycled polyester molded product described in any of [1] to

[17] above, and identifying the recycled polyester molded product based on the type and content of element (A) detected in the recycled polyester molded product.

[20] A method of using a recycled polyester molded product described in any of [1] to

[17] above as a recycled raw material.

[21] The method described in

[20] above, which utilizes blockchain.

[22] The blockchain comprises a network, a server, and multiple terminal devices, Tag information is stored on the aforementioned server. The method according to

[21] above, wherein the tag information includes at least information on the type of element (A) and information on the recycled polyester molded product linked to said information.

[23] The method according to

[22] above, wherein the tag information is read and used when recycling the recycled polyester molded product.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a recycled polyester molded article that has high versatility and can suppress quality deterioration even when a discriminating element is contained.

Brief Description of the Drawings

[0013] [Figure 1] It is an explanatory diagram showing an example of each process of a recycling system 1 according to an embodiment. [Figure 2] It is a block diagram showing an example of the system configuration of a blockchain 100. [Figure 3] It is a block diagram showing an example of the hardware configuration of terminal devices 130 to 135. [Figure 4] It is an example flowchart of each process performed in the recycling system 1. [Figure 5] It is a block diagram showing an example of the functional configuration of a terminal device 130 used in a film manufacturing process. [Figure 6] It is a block diagram showing an example of the functional configuration of a terminal device 135 used in a recycled raw material process.

Embodiments for Carrying Out the Invention

[0014] Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below. <"0000110"><Recycled Polyester Molded Article> The recycled polyester molded article of the present invention (hereinafter also simply referred to as "this molded article") contains polyester and a specific element (A) described later. There are no particular limitations on the shape of the molded product; it may be any shape such as film, plate, fiber, bottle, tube, rod, pellet, or other various product shapes. However, it is preferably a film, plate, or fiber, more preferably a film or plate, and even more preferably a film. When the molded product is a plate-shaped molded product, "plate-shaped" refers to any flat shape with a maximum thickness of 1 mm or more, and includes not only so-called plates with a thickness of 1 mm or more, but also films with a thickness of less than 1 mm. As a plate-shaped molded product, a thin plate shape is preferred, with a thickness of 2 mm or less preferred, more preferably less than 1 mm, even more preferably 500 μm or less, particularly preferably 400 μm or less, especially preferably 300 μm or less, and most preferably 250 μm or less. The lower limit is usually 1 μm, preferably 3 μm. For other product shapes, the product can be formed into various shapes, preferably films, plates, and other components, by general molding methods such as extrusion molding, injection molding, molten casting, and press molding. In each molding method, the apparatus and processing conditions are not particularly limited, and known methods can be used. In particular, it is preferable that the molded product is a film formed by extrusion molding, especially by the T-die method.

[0015] In this invention, "film" encompasses "sheet." Generally, a film is a thin, flat product with a thickness that is extremely small compared to its length and width, and whose maximum thickness is arbitrarily limited, and which is usually supplied in roll form (Japanese Industrial Standard JIS K6900:1994). Generally, a sheet, according to the definition in JIS, is a thin, flat product whose thickness is generally small relative to its length and width. However, since the boundary between sheet and film is not clear, in this invention, "film" encompasses "sheet." Therefore, "film" may also be "sheet."

[0016] <Recycled polyester film> The following will explain the composition of the molded product in detail, using the example of a case where the recycled polyester molded product is a recycled polyester film (hereinafter also simply referred to as "this film"). The film may be made of a polyester film containing polyester and a specific element (A) described later.

[0017] The polyester film may have a single-layer structure or a multi-layer structure. When the polyester film has a multi-layer structure, it is also called a multi-layer film. When the polyester film has a multi-layer structure, it may have a two-layer structure, a three-layer structure, or more, and may have four or more layers, as long as it does not depart from the gist of the present invention; the number of layers is not particularly limited. However, from the viewpoint of thinning and reducing the number of manufacturing steps, a single-layer structure or a multi-layer structure of three or fewer layers is preferred, but in the case of a multi-layer structure, a three-layer structure is preferred. A three-layer polyester film is a multi-layer film having an intermediate layer and surface layers on both sides of the intermediate layer. Furthermore, a multi-layer film with four or more layers may have multiple intermediate layers and surface layers on both sides of the laminated structure of the multiple intermediate layers. Furthermore, a two-layer multi-layer structure has two surface layers.

[0018] The polyester film (this film) may be an unstretched film (sheet) or a stretched film, but it is preferable that it is a film stretched in at least one direction, and preferably a biaxially oriented film stretched in two directions. By making the polyester film (this film) a biaxially oriented film, various mechanical properties tend to be improved.

[0019] [polyester] As described above, the polyester film is a film containing polyester, and it is preferable that polyester is the main component resin. Furthermore, if the polyester film has a multilayer structure, it is preferable that the main component resin of each layer is polyester. The term "main component resin" refers to the resin that makes up the largest proportion of the resins constituting the polyester film (or, in the case of a multilayer structure, the resins constituting each layer). For example, it refers to the resin that accounts for 50% or more by mass, especially 70% or more by mass, and among those, 80% or more by mass (including 100% by mass) of the resins constituting the polyester film (each layer).

[0020] The polyester film contains recycled polyester as polyester. The recycled polyester may be polyester that has been recycled from collected products, waste, etc., by a chemical recycling method involving chemical reactions, or it may be polyester that has been recycled from collected products, waste, etc., by a physical recycling method (mechanical recycling). Recycled polyester, if it is polyester, can be obtained by depolymerizing discarded polyester, and then repolymerizing the resulting intermediate or monomer to synthesize polyester again. Polyester recycled by physical recycling methods can be used as recycled resin by collecting various polyester resin products such as PET bottles, trays, and films, as well as scraps generated during the production process. After sorting and washing as necessary, the materials can be processed by melting, crushing, etc., and then further processed by granulation, micronization, pelletizing, flakeping, etc., to create a form that can be used as a raw material, such as powder, granules, pellets, or flakes. It is also preferable to use self-recovered recycled polyester, which is generated in the process of manufacturing molded products such as films, such as film scraps and film waste, that were not used as film products and have been collected by the company itself. By using such self-recovered recycled polyester, the characteristics of the recycled polyester can be understood more accurately, and recycled polyester film with more stable quality can be provided. In polyester films, recycled polyester may be used alone or in combination of two or more types.

[0021] When using recycled polyester, a portion of the polyester constituting the polyester film may be recycled polyester, or all of it may be recycled polyester. The recycled polyester content in this film is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, relative to the total polyester contained in the film. From the viewpoint of protecting the global environment, the higher the recycled polyester content, the better, and there is no particular limit as long as it is 100% by mass or less.

[0022] In the case of a multilayer structure, recycled polyester may be used in any of the layers, but it is preferable to use it in at least the intermediate layer, and it is also preferable to use it in both the intermediate layer and the surface layer. By using recycled polyester in at least the intermediate layer, the amount of recycled polyester used can be increased, and recyclability can be improved. Furthermore, when recycled polyester is used in the intermediate layer, a portion of the resin constituting the intermediate layer may be recycled polyester, or the entirety may be recycled polyester resin.

[0023] The polyester used in polyester films is not particularly limited. Specifically, examples include polyesters obtained by polycondensation of a dicarboxylic acid component and a diol component. Examples of dicarboxylic acid components include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, sodium 5-sulfisophthalate, adipic acid, dimer acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, and succinic acid. Furthermore, ester-forming derivatives of dicarboxylic acids, such as acid anhydrides like phthalic anhydride and trimellitic anhydride, and acid halides can also be used.

[0024] Examples of diol components include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, spiroglycol, isosorbide, and dimethylolpropionic acid, as well as potassium dimethylolpropionate. Furthermore, polyester can also be made from tricarboxylic acids such as trimellitic acid and trimesic acid, tetracarboxylic acids such as pyromellitic acid, and trivalent or higher alcohol components such as glycerin and trimethylolpropane. Furthermore, the polyester may also include biomass polyester obtained from plant-derived raw materials, such as polyester using biomass-derived ethylene glycol as a diol component.

[0025] The above polyester may be a homopolyester or a copolymerized polyester. If it is a homopolyester, it is preferably obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Among these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are more preferred as aromatic dicarboxylic acids, and saran is preferred among these aromatic dicarboxylic acids. Among the aliphatic glycols, ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol are more preferred, and ethylene glycol is even more preferred. Typical polyesters include polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), with PET being more preferable from the standpoint of versatility.

[0026] On the other hand, if the polyester is a copolymerized polyester, it contains a third component as a copolymer component, other than the compound that is the main component of the dicarboxylic acid component and the compound that is the main component of the diol component. For example, in PET, the third component is a component other than terephthalic acid and ethylene glycol. Specific examples of the dicarboxylic acid and diol, which are the main and third components, are as described above.

[0027] In polyester films, polyester may be used alone, or two or more types may be used in combination, and homopolyester and copolymerized polyester may be used in combination. Furthermore, in a multilayer structure, the polyester used in each layer may be of the same type or different types. Also, in each layer, polyester may be used alone, or two or more types may be used in combination.

[0028] In one embodiment of the present invention, the copolymer component is preferably 30 mol% or less, and more preferably 20 mol% or less, of the total dicarboxylic acid component in the polyester contained in the film. Furthermore, the copolymer component is preferably 30 mol% or less, and more preferably 20 mol% or less, of the total diol component in the polyester contained in the film. Among these, 80 mol% or more, preferably 90 mol% or more, of the polyester contained in the film is preferably PET having ethylene terephthalate units or PEN having ethylene-2,6-naphthalate units, with PET being more preferred from the viewpoint of versatility.

[0029] Furthermore, the content of diethylene glycol in the polyester contained in this film is preferably 5 mol% or less, and more preferably 3 mol% or less, out of 100 mol% of the total diol components. As described above, polyester often uses ethylene glycol as its main component as a diol, but diethylene glycol is produced as a by-product from ethylene glycol during polyester manufacturing. In this specification, this diethylene glycol is referred to as by-product diethylene glycol. When the amount of by-product diethylene glycol increases, it tends to degrade the performance of the polyester. Therefore, as described above, by controlling the diethylene glycol content to a certain level or less even after repeated recycling, the degradation of the film's performance due to recycling can be suppressed. Specifically, mechanical strength, thermal stability, and flatness are improved. In this specification, diethylene glycol in this film at a concentration of 5 mol% or less is considered a by-product diethylene glycol and is included within ethylene glycol. On the other hand, depending on the diethylene glycol content, more specifically, if diethylene glycol is present in a concentration exceeding 5 mol%, such diethylene glycol is distinguished from ethylene glycol.

[0030] The intrinsic viscosity of the polyester contained in this film is preferably 0.4 dL / g or more and 1 dL / g or less, more preferably 0.45 dL / g or more and 0.8 dL / g or less, even more preferably 0.5 dL / g or more and 0.75 dL / g or less, and even more preferably 0.55 dL / g or more and 0.7 dL / g or less. When recycled polyester is used, the intrinsic viscosity may decrease due to the thermal history of the manufacturing process, but by maintaining the intrinsic viscosity of the polyester above a certain level, quality deterioration due to the thermal history of the manufacturing process can be prevented. Furthermore, by solid-phase polymerization of part or all of the recovered recycled polyester to bring the intrinsic viscosity within the above range, film-forming properties and productivity can be improved. In this film, if two or more polyesters with different intrinsic viscosities are used, the intrinsic viscosity refers to the intrinsic viscosity of these mixed polyesters. The intrinsic viscosity can be measured according to a standard method. For example, 1 g of polyester from which incompatible components have been removed is accurately weighed, 100 mL of a phenol / tetrachloroethane mixed solvent (50 / 50 by mass ratio) is added to dissolve it, and the viscosity can be measured at 30°C using a viscosity measuring device.

[0031] There are no particular restrictions on the polymerization catalyst (Q) used for polyester films, and conventionally known compounds can be used, such as titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds, and calcium compounds. Among these, at least one of titanium compounds and antimony compounds is preferred. The content of metal elements derived from these polymerization catalysts (Q) should be such that, based on the total amount of the film, it is, for example, 1 ppm to 600 ppm by mass, preferably 5 ppm to 450 ppm by mass, and more preferably 10 ppm to 300 ppm by mass. In the case of titanium compounds, the content of titanium elements is, for example, 1 ppm to 70 ppm by mass, preferably 3 ppm to 40 ppm by mass, and more preferably 6 ppm to 20 ppm by mass. In the case of germanium compounds, the content of germanium elements is, for example, 10 ppm to 150 ppm by mass, preferably 30 ppm to 100 ppm by mass, and more preferably 50 ppm to 80 ppm by mass. In the case of antimony compounds, the content of antimony elements is, for example, 50 ppm to 400 ppm by mass, preferably 80 ppm to 300 ppm by mass, and more preferably 130 ppm to 250 ppm by mass. In the case of aluminum compounds, the content of aluminum element is, for example, 1 ppm by mass or more and 200 ppm by mass or less, preferably 10 ppm by mass or more and 150 ppm by mass or less, and more preferably 30 ppm by mass or more and 100 ppm by mass or less.

[0032] The resin contained in the polyester film may consist solely of polyester, but it may also contain resins other than polyester. Examples of resins other than polyester include polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polylactic acid resins, polybutylene succinate resins, polycarbonate resins, polyamide resins (including aramid resins), polyacetal resins, acrylic resins, ethylene-vinyl acetate copolymers, polymethylpentene resins, polyvinyl alcohol resins, cyclic olefin resins, polyacrylonitrile resins, polyethylene oxide resins, cellulose resins, polyimide resins, polyurethane resins, polyphenylene sulfide resins, polyphenylene ether resins, polyvinyl acetal resins, polybutadiene resins, polybutene resins, polyamide-imide resins, polyamide-bismaleimide resins, polyetherimide resins, polyetheretherketone resins, polyethersulfone resins, polyketone resins, polysulfone resins, and fluorine resins. These resins other than polyester can be used individually or in combination of two or more.

[0033] (Particle (P)) Polyester film may contain particles (P). The inclusion of particles (P) in the polyester film provides smoothness and also helps prevent scratches. The particles (P) can be incorporated into the surface of the polyester film; in the case of a single-layer film, they can be incorporated into the single resin layer, and in the case of a multilayer film, they can be incorporated into the surface layer. In the case of a multilayer film, the particles (P) can be incorporated into either of the surface layers, but it is preferable to incorporate them into both surface layers of the polyester film. Specific examples of particles (P) include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, as well as organic particles such as acrylic resin, styrene resin, urea resin, phenolic resin, epoxy resin, and benzoguanamine resin. Furthermore, precipitated particles obtained by precipitating and finely dispersing a portion of metal compounds such as catalysts during the polyester manufacturing process can also be used. Particles (P) may be used individually or in combination of two or more types. There are no particular restrictions on the shape of the particles (P) used; spherical, lumpy, rod-shaped, flattened, etc., may be used. Furthermore, there are no particular restrictions on their hardness, specific gravity, color, etc. Two or more types of these particles (P) may be used in combination as needed.

[0034] Furthermore, the average particle size of the particles (P) used is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 0.1 μm to 3 μm. By using an average particle size within the above range, the film can be given an appropriate surface roughness, ensuring good slipperiness and smoothness. The average particle size (P) can be determined by arbitrarily selecting 10 or more particles (P) present in the polyester film using a scanning electron microscope (SEM), measuring the diameter of each particle (P), and calculating the average value. In the case of non-spherical particles, the average of the longest and shortest diameters ((short diameter + long diameter) / 2) can be used to determine the diameter of each particle. The polyester film may contain a combination of two or more particles with different particle sizes.

[0035] The particle content in the layer containing the particles (for example, the surface layer in a multilayer film, or the single resin layer in a single-layer film) is preferably in the range of 0.0003% by mass or more and 5% by mass or less, more preferably in the range of 0.001% by mass or more and 3% by mass or less, and even more preferably in the range of 0.01% by mass or more and 0.3% by mass or less. By setting the particle content within the above range, it becomes easier to impart slipperiness to the film while ensuring its transparency.

[0036] In addition to the particles mentioned above, the polyester film may also contain, as necessary, at least one additive (other additive) selected from the following: nucleating agents, antioxidants, color inhibitors, pigments, dyes, ultraviolet absorbers, mold release agents, lubrication agents, flame retardants, antistatic agents, etc.

[0037] [Element (A) and Element (B)] The polyester film, specifically this film, contains at least one element (A) selected from Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, Nb, Ca, Mn, S, Cr, Cu, Zn, and Co. The total content of element (A) in this film is between 0.1 ppm by mass and 5000 ppm by mass. Each of the above elements (A) can be detected by X-ray fluorescence analysis (XRF) and other analytical instruments. Since the detection limit in XRF is low, element (A) can be used as an identifier to easily identify this film. Furthermore, element (A) has a relatively large Clark number, making it highly practical. Moreover, even when incorporated into a polyester film, element (A) is less likely to cause problems such as hydrolysis of the polyester, precipitation on the surface inhibiting the hardening of the functional layer laminated on the surface, or contamination of the functional layer and degrading its function. This makes the film less susceptible to quality degradation. Additionally, as described later, element (A) may be incorporated into the functional layer, and even in such cases, it similarly does not significantly degrade the quality of the film.

[0038] From the viewpoint of practicality, XRF detection accuracy, and suppression of film quality degradation, it is preferable to use at least one of the above elements (A), namely Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb, and more preferably at least one of Al, Mg, Ge, and Sc. Furthermore, element (A) may be used alone or in combination of two or more elements.

[0039] Furthermore, it is preferable that the polyester film, i.e., the film in question, contains two or more types of element (A). By containing two or more types of element (A), the film can be identified with high precision using element (A) as the identifying element. When using two or more elements, for example, a combination of at least one element (A1) selected from Al, Mg, Ge, and Sc and at least one element (A2) selected from Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb is preferred. Similarly, a combination of at least one element (A1) selected from Al, Mg, Ge, and Sc and at least one element (A3) selected from Ca, Mn, S, Cr, Cu, Zn, and Co is also preferred. As described above, using a combination of elements (A1) and (A2) provides a dual identification function, allowing for more detailed identification. Furthermore, these elements have relatively large Clark numbers, making them practically useful, and they also have the advantage of not easily impairing the various physical properties of the film. Using a combination of elements (A1) and (A3) also provides a dual identification function, allowing for more detailed identification. Furthermore, a combination of at least one element (A2) selected from Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb, and at least one element (A3) selected from Ca, Mn, S, Cr, Cu, Zn, and Co is also preferred. By using a combination of elements (A2) and (A3), a dual identification function can be provided, allowing for more detailed identification.

[0040] Furthermore, the polyester film, i.e., this film, may also use at least one element (B) selected from Pd, Os, Ir, Pt, Au, Y, Mo, Tc, In, Sn, Te, Cs, La, Ce, K, Ti, Cl, F, V, Ru, Rh, Ag, Br, Ga, I, in addition to element (A). Element (B) may be rare, corrosive to metals, cause coloration or gel formation in the film, or be practically unsuitable for use as an identification substance in polyester films, but it is detectable by XRF and other analytical instruments. Therefore, these elements (B) can be used depending on the application, and by using them in combination with element (A) as an identification substance, identification or authentication can be achieved with higher detection accuracy.

[0041] As for element (B), among the above, at least one element (B1) selected from Pd, Os, Ir, Pt, Au, Y, Mo, Tc, In, Sn, Te, Cs, La, and Ce is preferred because, although rare, it is highly stable and its detection limit by XRF is about 0.1 to 1 mass ppm. Among these, Y, Mo, Tc, In, Sn, Te, Cs, La, and Ce are more preferred. Furthermore, among the elements listed above, K, Ti, Cl, F, V, Ru, Rh, Ag, Br, Ga, and I are preferred as element (B) in terms of versatility, and among these, K, Ti, Cl, F, V, Br, Ga, and I are more preferred. Furthermore, element (B) may be used alone or in combination of two or more elements.

[0042] If element (A) is a metallic element, it may be incorporated into the polyester film as the metal itself, but from the viewpoint of suppressing deterioration of the quality of the polyester film, it is preferable to incorporate it into the polyester film as a metallic compound such as a metal salt. In this specification, metallic elements also include so-called metalloids such as germanium and silicon. Examples of metallic compounds include halides such as chlorides and bromides, oxides, sulfides, nitrides, sulfates, and nitrates, but organometallic compounds such as organometallic salts may also be used. Furthermore, if element (A) is a nonmetallic element such as sulfur or phosphorus, it may be incorporated into the polyester film in the form of sulfides, phosphates, phosphites, phosphinates, etc.

[0043] Furthermore, if element (B) is a metallic element, it may be incorporated into the polyester film as the metal itself, but it is preferable that it be incorporated into the polyester film as a metallic compound such as a metal salt. Examples of metallic compounds are the same as those for element (A). Also, if element (B) is a halogen element such as a fluorine atom, chlorine atom, bromine atom, or iodine atom, it may be incorporated into the polyester film in the form of fluoride, chloride, bromide, or iodide.

[0044] Element (A) may be incorporated into the polyester film by blending a substance containing two or more elements (A) into the polyester film. Similarly, element (B) may be incorporated into the polyester film by blending a substance containing two or more elements (B). Furthermore, one or more elements (A) and one or more elements (B) may be incorporated into the polyester film by blending a substance containing both. Specifically, the above-mentioned compounds, such as halides, sulfides, sulfates, phosphates, phosphites, and phosphinates, may be included in the polyester film, containing two or more elements (A) or (B), or containing one or more elements (A) and one or more elements (B).

[0045] Furthermore, element (A) may also be incorporated into the film by incorporating a metal element nanocomposite containing element (A) into the film. A metal element nanocomposite is a particle having a nanoscale particle size formed by the clustering of two or more metal elements. Examples of metal element nanocomposites are described in Noble-Metal High-Entropy-Alloy Nanoparticles: Atomic-Level Insight into the Electronic Structure, J. Am. Chem. Soc. 2022, 144, 8, 3365-3369. It is preferable to use a metal element nanocomposite that contains two or more elements (A), but it is also acceptable to use one or more elements (A) and one or more elements (B), or to use one or more elements (B).

[0046] (Content of element (A)) The element (A) content (a1) in this film (i.e., this molded product) is between 0.1 ppm by mass and 5000 ppm by mass. If the content (a1) is less than 0.1 ppm by mass, it falls below the detection limit of analytical instruments such as XRF, making it impossible to identify this film. If it exceeds 5000 ppm by mass, it is likely to degrade the quality of this film and the functional layer laminated to it. Note that the content (a1) is the ratio of the total content of element (A) in this film (i.e., this molded product) to the total amount of this film (i.e., this molded product). From the viewpoint of preventing quality deterioration, the content (a1) of element (A) is preferably 3000 ppm by mass or less, more preferably 2000 ppm by mass or less, even more preferably 1000 ppm by mass or less, and even more preferably 500 ppm by mass or less. The content (a1) of element (A) is not particularly limited as long as it can be detected by an analytical instrument such as an XRF, but is preferably 1 ppm by mass or more, more preferably 5 ppm by mass or more, and even more preferably 10 ppm by mass or more.

[0047] Furthermore, the content of each element constituting element (A) varies depending on the type of element used, but considering the detection limit, for example, when Al, Si, or S is used as the identification substance, the content of each element is preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, even more preferably 50 ppm by mass or more, and even more preferably 3000 ppm by mass or less, more preferably 2000 ppm by mass or less, even more preferably 1000 ppm by mass or less, and even more preferably 500 ppm by mass or less, relative to the entire film (i.e., the molded product). Furthermore, for example, when using either Mg or P as an identification substance, the content of each element is preferably 100 ppm by mass or more, more preferably 150 ppm by mass or more, even more preferably 200 ppm by mass or more, and preferably 3000 ppm by mass or less, more preferably 2000 ppm by mass or less, even more preferably 1000 ppm by mass or less, and even more preferably 500 ppm by mass or less, relative to the entire film. Furthermore, for example, when using any of Sc, Fe, Ba, Ca, Mn, Cr, Ni, Cu, Co, or Sb as an identifying substance, the content of each element is preferably 1 ppm by mass or more, more preferably 5 ppm by mass or more, even more preferably 10 ppm by mass or more, and also preferably 2000 ppm by mass or less, more preferably 1000 ppm by mass or less, even more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less. Furthermore, for example, when using Ge, Rb, Zr, Sr, Zn, or Nb as an identifying substance, the content of each element is preferably 0.5 ppm by mass or more, more preferably 1 ppm by mass or more, even more preferably 5 ppm by mass or more, and also preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 300 ppm by mass or less, and even more preferably 100 ppm by mass or less.

[0048] (Content of element (B)) The element (B) content (b1) in this film (i.e., this molded product) is not particularly limited, but is, for example, between 0.1 ppm by mass and 2000 ppm by mass. A content (b1) of 0.1 ppm by mass or more allows element (B) to be detected by XRF and other analytical instruments, enabling more accurate identification of this film. Furthermore, keeping the content (b1) below 2000 ppm by mass makes it easier to suppress quality degradation of this film and the functional layer laminated to it due to element (B). Note that content (b1) is the ratio of the total content of element (B) to the total amount of this film. From the viewpoint of preventing quality deterioration, the content (b1) of element (B) is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 300 ppm by mass or less, and even more preferably 200 ppm by mass or less. The content (b1) of element (B) is not particularly limited as long as it can be detected by analytical instruments such as XRF, but is preferably 1 ppm by mass or more, more preferably 5 ppm by mass or more, and even more preferably 10 ppm by mass or more.

[0049] Furthermore, the content of each element constituting element (B) varies depending on the type of element used, but considering the detection limit, for example, when Cl is used as the identification substance, the content of element Cl is preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, even more preferably 50 ppm by mass or more, and also preferably 1500 ppm by mass or less, more preferably 1000 ppm by mass or less, even more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less. Furthermore, for example, when F is used as an identification substance, the content of element F is preferably 100 ppm by mass or more, more preferably 150 ppm by mass or more, even more preferably 200 ppm by mass or more, and preferably 1500 ppm by mass or less, more preferably 1000 ppm by mass or less, even more preferably 500 ppm by mass or less, and even more preferably 400 ppm by mass or less. Furthermore, for example, when using any of K, Ti, V, Ag, Os, Ir, In, Sn, Te, I, Cs, La, or Ce as an identifying substance, the content of each element is preferably 1 ppm by mass or more, more preferably 5 ppm by mass or more, even more preferably 10 ppm by mass or more, and also preferably 500 ppm by mass or less, more preferably 300 ppm by mass or less, even more preferably 100 ppm by mass or less, and even more preferably 50 ppm by mass or less. Furthermore, for example, when using Ru, Rh, Pd, Pt, Au, Br, Ga, Y, Mo, or Tc as an identifying substance, the content of each element is preferably 0.5 ppm by mass or more, more preferably 1 ppm by mass or more, even more preferably 5 ppm by mass or more, and also preferably 500 ppm by mass or less, more preferably 100 ppm by mass or less, even more preferably 50 ppm by mass or less, and even more preferably 30 ppm by mass or less.

[0050] Furthermore, in this invention, the metal elements such as Ge, Sb, Mn, Al, Mg, and Ca that constitute the polymerization catalyst (Q) (metal elements derived from the catalyst) constitute element (A). When metal elements derived from the catalyst constitute element (A), it is preferable that element (A) contains two or more elements. Even when metal elements derived from the catalyst constitute element (A), having two or more elements in element (A) makes it easier for element (A) to exhibit its identification function. In this case, the two or more elements (A) may include elements derived from the polymerization catalyst (Q) and elements other than those derived from the polymerization catalyst (Q), or they may consist solely of elements derived from the polymerization catalyst (Q). Polymerization catalysts (Q) are generally used alone, and even when two or more are used in combination, the combinations are limited. Even if two or more elements (A) consist solely of elements derived from polymerization catalyst (Q), they can be easily distinguished from the polymerization catalyst combinations of polyester films available on the market, and thus the distinguishing function can be fully exercised. Furthermore, when using elements (A) such as Ge, Sb, Mn, Al, Mg, and Ca as the polymerization catalyst (Q), and when using two or more types of elements (A), the combination of elements (A1) and (A2), the combination of elements (A1) and (A3), or the combination of elements (A2) and (A3) described above is preferred.

[0051] Furthermore, from a similar viewpoint, if the catalyst-derived metal element constitutes element (A), it is also preferable that the film contains at least one element (A) and at least one element (B).

[0052] When element (A) is composed of metallic or nonmetallic elements derived from particles (P), it is preferable that element (A) contains two or more elements. Even when element (A) is composed of metallic or nonmetallic elements derived from particles (P), having two or more elements in element (A) makes it easier to provide an identification function through element (A). In this case, the two or more elements (A) may include elements derived from particles (P) and elements other than those of particles (P), or they may consist only of elements derived from particles (P). Furthermore, the two or more elements (A) may include elements derived from the polymerization catalyst (Q) and elements derived from particles (P). Furthermore, element (A) may be composed of metallic or non-metallic elements derived from the other additives mentioned above.

[0053] However, even if element (A) is composed of a metallic element derived from the polymerization catalyst (Q) or a metallic or nonmetallic element derived from the particles (P), element (A) may consist of only one type. In such cases, for example, the element (A) can be made to exhibit a distinguishing function by making the content of element (A) different from the catalytic amount of polymerization catalyst (Q) or the content of particles (P) in polyester films distributed on the market. Furthermore, polymerization catalysts (Q) are generally used to produce specific polyesters, and polyester films containing a specific polymerization catalyst (Q) may contain a specific type of polyester. Therefore, this film containing such a specific polymerization catalyst (Q) can be effectively used as an identifying element to identify the type of polyester. In such cases, element (A) may consist of only one type, or it may contain two or more types of element (A).

[0054] Furthermore, when particles (P) are used, silica and alumina (aluminum oxide) are preferred as particles (P), with silica being particularly preferred. Therefore, it is preferable that this film contains one or both of Si and Al as elements (A) derived from particles (P). In this case, if there are two or more elements (A), the elements (A) may be any combination of elements (A1) and (A2), elements (A1) and (A3), or elements (A2) and (A3), or any other combination of elements may be used. Of course, even if it contains elements (A) derived from particles (P), element (A) may be only one type. Furthermore, if the elements derived from the particles (P) constitute element (A), it is preferable that the film also contains at least one element (A) and at least one element (B).

[0055] Furthermore, in the present invention, when two or more elements (A) are used, particularly preferred combinations are Al and Mg, Ge and Ba, Al and Ge, Al and Ba, Mg and Ge, and Mg and Ba, from the viewpoint of providing a dual identification function and exhibiting a more detailed identification function, as well as from the viewpoint of minimizing the impact on the Clark number and the physical properties of the film. More preferably, the combination is Al and Mg, Ge and Ba.

[0056] Furthermore, in the present invention, when using one or more elements (A) and one or more elements (B), particularly preferred combinations that can provide a dual identification function and enable more detailed identification are Al and Ti, Al and Ag, Al and Pt, Mg and Ti, Mg and Ag, Mg and Pt, Ge and Ti, Ge and Ag, Ge and Pt, Ba and Ti, Ba and Tg, and Ba and Pt.

[0057] Furthermore, in the case of a polyester film with a multilayer structure, it is preferable that element (A) be contained in one of the layers constituting the multilayer structure. In this case, element (A) may be contained in all layers of the multilayer structure, or it may be contained in only some of the layers. Furthermore, in multilayer films with three or more layers, it is preferable that element (A) is contained in at least the intermediate layer. In this case, element (A) is not contained in the surface layer, or if it is contained, the content of element (A) in each surface layer should be lower than the content of element (A) in the intermediate layer. By containing element (A) in the intermediate layer and not containing element (A) in the surface layer, or by keeping the content of element (A) in the surface layer low, it is possible to prevent element (A) from bleeding out and degrading the quality of the film. Also, when a functional layer is laminated on the surface of the film, it is possible to prevent element (A) from inhibiting these curing reactions or mixing into the functional layer and degrading the quality of the functional layer. Furthermore, it is preferable that element (A) contained in the intermediate layer be used as an identification element. However, as will be explained later, some analytical instruments may only be able to analyze the surface of this film. If such an analytical instrument is used, it is advisable to include element (A), which is the identifying element, in the surface layer.

[0058] In particular, elements (A) other than those derived from the polymerization catalyst (Q) and particles (P) (hereinafter sometimes referred to as element (A')) should be contained in the intermediate layer but not in the surface layer, and even if they are contained, the content of element (A') in each surface layer should be lower than the content of element (A') in the intermediate layer.

[0059] Furthermore, if the polyester film has a multilayer structure and contains element (B), it is preferable that element (B) be contained in one of the layers constituting the multilayer structure. In this case, element (B) may be contained in all layers of the multilayer structure, or it may be contained in only some of the layers. Furthermore, in films with a multilayer structure of three or more layers, it is preferable that element (B) is contained in at least the intermediate layer. In this case, element (B) is not contained in the surface layer, or if it is contained, the content of element (B) in each surface layer should be lower than the content of element (B) in the intermediate layer. By containing element (B) in the intermediate layer and not containing element (B) in the surface layer, or by keeping the content of element (B) in the surface layer low, it is possible to prevent element (B) from bleeding out and degrading the quality of the film. Also, as will be described later, when a functional layer is laminated on the surface of the film, it is possible to prevent element (B) from inhibiting these curing reactions or mixing into the functional layer and degrading the quality of the functional layer. Furthermore, it is preferable that element (B) contained in the intermediate layer be used as an identification element. However, as will be explained later, some analytical instruments may only be able to analyze the surface of this film. If such an analytical instrument is used, it is advisable to include the identifying element (B) in the surface layer.

[0060] Furthermore, element (A) preferably contains at least one of Sc, Rb, Ba, Sr, Cr, or Cu as an identifying element. These elements have virtually no track record of use in general-purpose polyester films, and by using one of them, precise identification of this film becomes possible. These elements typically constitute element (A') described above.

[0061] Furthermore, if the polyester film, i.e., the film contains two or more elements (A), at least one element may be used as the identifying element, and the remaining elements may not be used as identifying elements. Typically, elements not used as identifying elements are the polymerization catalyst (Q) or particles (P) mentioned above, but elements (A) derived from other materials such as additives may also not be used as identifying elements. Element (B) may or may not be used as an identifying element. Furthermore, if there are two or more types of element (B), at least one may be used as an identifying element, and the rest may not be used as identifying elements.

[0062] The thickness of the polyester film is not particularly limited as long as it is within the range that allows it to be formed as a film, but is preferably 1 μm to 1000 μm, more preferably 3 μm to 500 μm, even more preferably 5 μm to 300 μm, and even more preferably 10 μm to 200 μm.

[0063] <Method for manufacturing polyester film> Next, we will specifically describe examples of polyester film production, but the production is not limited to the following examples. For example, when producing a biaxially oriented polyester film, first, a resin raw material containing polyester, a component containing element (A), an optional component containing element (B), particles (P), and other additives are blended in any proportion, the components are mixed using an extruder, the resulting resin composition is extruded from a die as a molten sheet, and cooled and solidified on a cooling roll such as a rotating cooling drum to obtain an unstretched sheet. In this case, it is preferable to improve the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and electrostatic application adhesion and / or liquid coating adhesion methods are preferably employed. Furthermore, the polyester blended as a resin raw material may contain recycled polyester as described above. Next, the obtained unstretched sheet is stretched in two axes. In this case, first, the unstretched sheet is stretched in one direction using a roll or tenter type stretcher. The stretching temperature is usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, it is stretched in a direction perpendicular to the first stretching direction, in which case the stretching temperature is usually 70 to 170°C, and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Then, the film is heat-treated at a temperature of typically 180-270°C under tension or under relaxation of 30% or less to obtain a biaxially oriented film. In the stretching described above, a method of stretching in one direction in two or more stages can also be employed. In that case, it is preferable to ensure that the final stretching ratios in both directions are within the above ranges.

[0064] Furthermore, simultaneous biaxial stretching can also be used in the production of polyester film. Simultaneous biaxial stretching is a method of simultaneously stretching and oriented the aforementioned unstretched sheet in the machine direction (longitudinal direction) and width direction (transverse direction) while the temperature is controlled, usually at 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area. Then, heat treatment is carried out at a temperature of typically 170-250°C under tension or under relaxation of 30% or less to obtain a stretched and oriented film. For the simultaneous biaxial stretching apparatus employing the above stretching method, conventional known stretching methods such as screw type, pantograph type, and linear drive type can be used.

[0065] <Functional Layer> The above description assumes that the film consists of a single polyester film, but the film may also be a laminated film. A laminated film comprises a polyester film and a functional layer laminated on at least one side of the polyester film. The components of the functional layer are not particularly limited, but it is preferable that it consists of a resin layer. Examples of functional layers include a hard coat layer, an antistatic layer, a release layer, an easy-adhesion layer, an adhesive layer, a printed layer, a decorative layer, a light-shielding layer, an ultraviolet-shielding layer, a refractive index adjusting layer, and an oligomer encapsulation layer. The functional layer may be formed by applying a coating solution containing a resin component and other components that form the functional layer to the surface of the film and curing and drying it as necessary, or by laminating a pre-formed functional layer onto at least one side of the film, or by lamination by other methods. Furthermore, the formation of the functional layer may be carried out by in-line coating, which treats the film surface during the film manufacturing process, or by off-line coating, which is applied to the manufactured film outside the system.

[0066] In the present invention, the functional layer may contain a component containing element (A) and optionally a component containing element (B). Since an identification function can be imparted by including element (A), etc., in the resin composition constituting the functional layer, the process is simple and preferable. Furthermore, if the identification function is to be removed, this can be easily achieved by removing the functional layer, which is preferable. Furthermore, when the functional layer contains a component containing element (A), the total amount of element (A) in the film (i.e., the functional layer and the polyester film) relative to the entire film (content rate (a1)) should be adjusted to fall within the above range. Similarly, when the functional layer contains a component containing element (B), the total amount of element (B) in the film relative to the entire film (content rate (b1)) should be adjusted to fall within the above range. When a functional layer is provided, the component containing element (A) may be included only in the polyester film, only in the functional layer, or in both the polyester film and the functional layer.

[0067] Even when element (A) is included in the functional layer, the quality of the film can be made less susceptible to deterioration by keeping the content (a1) below the upper limit mentioned above. Similarly, even when element (B) is included in the functional layer, the quality of the film can be made less susceptible to deterioration by keeping the content (b1) below the upper limit mentioned above. Details of elements (A) and (B) when included in the functional layer, or in both the functional layer and the polyester film, and the components containing them, are as described above. Furthermore, as described above, element (A) may be included in two or more types in this film. In that case, it may be included in the polyester film in two or more types as described above, or in the functional layer in two or more types, or in the polyester film in one or more types and in the functional layer in one or more types. Element (B) may also be included in the functional layer, the polyester film, or both as appropriate. The thickness of the functional layer is not particularly limited, but in the case of in-line coating, it is, for example, in the range of 0.001 μm to 1 μm, preferably 0.01 μm to 0.6 μm, and more preferably 0.03 μm to 0.3 μm. In the case of offline coating, it is, for example, 0.01 μm to 250 μm, preferably 0.1 μm to 100 μm, and more preferably 1 μm to 50 μm. In particular, when the functional layer is a release layer, the thickness is, for example, in the range of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 3 μm, and even more preferably 0.5 μm to 1 μm. If the thickness is 0.01 μm or more, it becomes easier to obtain the desired release properties, and if it is 10 μm or less, it becomes easier to suppress the occurrence of blocking and deterioration of appearance. If the functional layer is an adhesive layer, its thickness is, for example, in the range of 1 μm to 250 μm, preferably 5 μm to 200 μm, more preferably 10 μm to 150 μm, and even more preferably 15 μm to 100 μm. If the thickness is 1 μm or more, it becomes easier to obtain the desired adhesive strength, and if it is 250 μm or less, it becomes easier to suppress insufficient curing when forming the adhesive layer. If the functional layer is a printed layer, its thickness is, for example, in the range of 0.1 μm to 20 μm, preferably 0.4 μm to 15 μm, more preferably 0.8 μm to 10 μm, and even more preferably 1 μm to 5 μm. If the thickness is 0.1 μm or more, it is possible to easily impart design features, and if it is 20 μm or less, it is easier to suppress insufficient curing when forming the printed layer. If the functional layer is a hard coat layer, the thickness is, for example, in the range of 0.1 μm to 50 μm, preferably 0.5 μm to 30 μm, more preferably 1 μm to 20 μm, and even more preferably 1.5 μm to 15 μm. If the thickness is 0.1 μm or more, it is easier to obtain sufficient surface hardness, and if it is 50 μm or less, it is easier to suppress the occurrence of blocking and deterioration of the film's flatness due to wrinkles, etc.

[0068] <Physical properties of this film> The ester cyclic trimer content of this film is preferably 10,000 ppm by mass or less, more preferably 5,000 ppm by mass or less, and even more preferably 3,000 ppm by mass or less. By limiting the ester cyclic trimer content to 10,000 ppm by mass or less, this film can prevent whitening due to oligomer precipitation, for example. The method for measuring the ester cyclic trimer content is as follows. The film is heated in air at 180°C for 30 minutes. Afterward, the heat-treated film is shaped into a box with dimensions of 10 cm x 10 cm x 3 cm, with the measurement surface facing inward and the top open. Next, 4 ml of dimethylformamide (DMF) is placed inside the box and left for 3 minutes, after which the DMF is collected. The collected DMF is then supplied to a liquid chromatograph (e.g., Shimadzu Corporation: LC-7A) to determine the amount of ester cyclic trimers in the DMF. The amount of ester cyclic trimers in the DMF is determined from the peak area ratio of the standard sample peak area to the measured sample peak area (absolute calibration curve method).

[0069] As described above, in order to suppress the content of ester cyclic trimers, it is preferable to manufacture polyester films using polyester with a low oligomer content as the raw material. Various known methods can be used to manufacture polyester with a low oligomer content, such as solid-phase polymerization after polyester production. Alternatively, polyester with a low oligomer content may be esterified or transesterified, and then further subjected to melt polycondensation under reduced pressure at a higher reaction temperature to obtain the polyester film. Furthermore, the ester cyclic trimer content only needs to be within the range described above for the surface of the polyester film. Also, if the film is a multilayer film, the ester cyclic trimer content in the surface layer should be within the range described above. Therefore, a polyester with a low oligomer content should be used for the surface layer. Furthermore, when using recycled polyester, the polyester may degrade, leading to an increase in the oligomer content and a decline in quality. However, as described above, controlling the oligomer content makes it easier to prevent quality degradation even when using recycled polyester.

[0070] The carboxyl group concentration (COOH concentration) of this film is preferably 25 eq / ton or more and 60 eq / ton or less. By keeping the COOH concentration below a certain level, this film exhibits good hydrolysis resistance and high durability. While carboxyl groups are usually terminal carboxyl groups located at the ends of polymer chains, they do not necessarily have to be located at the ends. Note that when recycled polyester is used, thermal decomposition progresses, leading to a higher COOH concentration and reduced durability. However, by controlling the COOH concentration to below a certain level, the decrease in durability caused by the use of recycled polyester can be suppressed. Furthermore, a COOH concentration of 25 eq / ton or more results in good production efficiency. A COOH concentration of 27 eq / ton or more and 60 eq / ton or less is more preferable, and 30 eq / ton or more and 45 eq / ton or less is even more preferable.

[0071] The method for measuring COOH concentration is as follows, for example: As an automatic titrator, we will use the AUT-501 (automatic burette ABT-511: using a 5mL syringe) manufactured by Toa DKK. For the titration, we will use a 0.01N sodium hydroxide solution in benzyl alcohol. The film will be crushed, and 0.5g of the crushed sample will be accurately weighed and placed in a test tube. 25mL of benzyl alcohol will be added, and the sample will be dissolved at 195°C for 9 minutes. After dissolving, the test tube will be immersed in ice water for 40 seconds and cooled to room temperature. Next, 2mL of ethanol will be added. This test tube will be placed on a stirrer for measurement and stirring, a pH electrode and titration nozzle will be inserted, and automatic titration will be performed while stirring. As a blank, the same procedure will be performed without dissolving the sample, and the amount of terminal carboxyl groups will be calculated using the following formula. Terminal carboxyl group weight (eq / ton) = (ab) × 0.01 × f / w (Here, a is the volume (μL) of the 0.01N sodium hydroxide benzyl alcohol solution required for titration, b is the volume (μL) of the 0.01N sodium hydroxide benzyl alcohol solution required for titration without the sample, w is the amount of the sample (g), and f is the titer of the 0.01N sodium hydroxide benzyl alcohol solution.)

[0072] The volume resistivity of this film is 1.0 × 10⁻⁶ 7 Ω cm or more 1.0×10 9 It is preferable that the volume resistivity is Ω·cm or less. Having the volume resistivity within the above range makes it easier to adhere the molten film to the cast roll using static electricity, thereby improving film formation. Furthermore, the volume resistivity is 5.0 × 10⁻⁶. 7 Ω cm or more 5.0×10 8 It is more preferable that the value be Ω·cm or less. The volume resistivity is the volume resistivity at 285°C, and can be determined by inserting electrodes into the molten film, applying a voltage (DC100V), and measuring the molten resistivity between the electrodes.

[0073] In the above description, it has been assumed that the film (polyester film) contains recycled polyester, but the film does not have to contain recycled polyester. Therefore, the polyester used in the film may all be virgin polyester. Furthermore, in this specification, when the term "recycled polyester film" is used, it includes not only films that contain recycled polyester, but also films that do not contain recycled polyester but are used for recycling. Similarly, when the term "recycled polyester molded product" is used, it includes not only molded products that contain recycled polyester, but also molded products that do not contain recycled polyester but are used for recycling. Because all the polyester used in this film is virgin polyester, it is possible to track and understand the film at every stage, from the initial manufacturing stage to sales, collection, sorting, and recycling. This is expected to facilitate not only further recycling but also smoother manufacturing and sales processes. Even without containing recycled polyester, this film can be identified by using element (A), or elements (A) and (B) as identifying elements. This allows for the identification of the type of polyester used in the film, its product grade, whether it is single-layer or multi-layer, the content of each polyester, the composition of the film, and its intended use. This identified information can then be usefully utilized when recycling the film.

[0074] <Method of identifying this film> The method for identifying this film (hereinafter also referred to as "this identification method") involves analyzing this film with a known analytical device and identifying the film based on the type of element (A) detected. The analytical instruments used in this identification method include those employing analytical techniques such as XRF (X-ray fluorescence analysis), XPS (X-ray photoelectron spectroscopy), and XRD (X-ray diffraction). Among these, XRF is preferred from the viewpoint of being able to detect the type and content of the identification element while keeping the analytical instrument simple.

[0075] XRF is a technique that detects fluorescent X-rays generated by irradiated X-rays or gamma rays, and measures elements and their quantities by analyzing their energy and spectral distribution using a spectroscopic crystal. Therefore, by using XRF, it is possible to detect the type of element and its content. XPS measures the kinetic energy distribution of photoelectrons emitted by X-ray irradiation, detecting information about the types, amounts, and chemical bonding states of elements present on the sample surface (to a depth of a few nanometers). Therefore, by using XPS, it is possible to detect the types and content of elements. Furthermore, since it can detect the bonding state of elements, it is also possible to detect information about the materials that constitute element (A). XRD is a technique that involves irradiating a sample with X-rays and obtaining various information from the resulting diffraction pattern. Using XRD, it is possible to detect the type of element, the element's content, and the composition of the substances that make up element (A).

[0076] When analyzing this film, it is preferable to analyze it in its original state. However, if analysis is not possible in its original state, the film may be processed as appropriate before analysis. Furthermore, while any known analytical device can be used, a handheld reader or a belt conveyor type reader is preferred from the viewpoint of versatility and ease of analysis. Handheld readers and belt conveyor type readers are already in practical use in XRF, for example.

[0077] This film may contain a specific type of element (A) as an identifying element to indicate, for example, that it contains recycled polyester. The detection of this specific type of identifying element allows the film to be identified as containing recycled polyester.

[0078] Furthermore, in this identification method, it is also preferable to detect the type and content of element (A) contained in the film (for example, the content in the film, the content in a specific layer of the film, etc.) and identify the film based on the detected type and content of element (A). In the case of a multilayer structure, the specific layer is preferably an intermediate layer. Preferably, this film contains a specific type of element (A) as an identifying element in a specific concentration to indicate, for example, that it contains recycled polyester. In such cases, not only the type of element (A) but also its concentration can be detected, and by containing a specific element (A) in a specific concentration, it can be identified as a film containing recycled polyester. In this way, by detecting the type of element (A) and its concentration, and identifying the film based on the detection results, more accurate identification can be achieved. Furthermore, in the film used in this identification method, it is sufficient that element (A) is contained in such a way that at least one of the types of element (A) and its content differs from conventional polyester films on the market.

[0079] In this identification method, the content of element (A) contained in the film is determined to be at a specific content if the detected content is similar to the reference value, taking into account measurement errors and other factors. For example, regarding the content, if the measured value / reference value is approximately 0.8 to 1.2, preferably 0.9 to 1.1, and more preferably 0.95 to 1.05, it is determined to be at a specific content. The reference value here is the content of the identification element that the film being analyzed should contain, and may be set in advance based on, for example, the amount of the identification element actually blended into the recycled polyester. Alternatively, the reference value may be set based on the results of an analysis of the film containing recycled polyester that was performed in advance. The content of element (A) here does not have to be the content of the entire film, but may be the content of a part of the film, for example, the content of the polyester film, the content of the functional layer, or the content of the surface layer or intermediate layer. The same applies to element (B).

[0080] Furthermore, in this identification method, if the film contains two or more elements (A) and two or more elements (A) are used as two or more identification elements, the film may be identified as containing recycled polyester by detecting the presence of two or more elements (A) (identification elements). Alternatively, if two or more identification elements are used, the film may be identified as containing recycled polyester by detecting the presence of each of the two or more identification elements (A) at a specific concentration. By using two or more identification elements, even more accurate identification becomes possible. Furthermore, if this film contains element (B) in addition to element (A), and both element (A) and element (B) are used as identifying elements, the procedure should be the same as when two or more elements (A) are used as identifying elements.

[0081] Furthermore, in this identification method, when using XPS or XRD in the analytical instrument, not only the type of identification element but also information about the substances constituting the identification element, such as the bonding state of the identification element and the composition of the substances constituting the identification element (identification substance), may be detected, and based on the detected information, it may be identified whether or not the film contains recycled polyester. By detecting not only the identifying elements but also information about the identifying substance (bonding state and composition), it is possible to determine the presence or absence of the identifying substance based on that information. In other words, identification can be performed not only based on the identifying elements but also on the presence or absence of the identifying substance. Therefore, even if the film does not contain the identifying substance intended for identification, and an element (A) not intended for identification is present in a form other than the identifying substance, such a film will not be identified as containing recycled polyester, thus enabling more precise identification. Furthermore, when identification is performed based on the type of element (A) and information on the identifying substance, identification may also be performed based on the content of element (A).

[0082] In this identification method, countless combinations of element (A) type and its content are possible. By linking information about element (A) type and its content (i.e., reference value) (identification element information described later) with information about the film, the type and content of element (A) of the film obtained through analysis can be used to determine not only whether the film contains recycled polyester, but also information about the film (i.e., the molded product) (hereinafter sometimes referred to as "film information"). Furthermore, it becomes possible to track the film. Similarly, when the identification method is based on information about the identifying substance (composition, bonding state, etc.) as described above, by preparing variations of the identifying substance and linking the information of each identifying substance with the film information in advance, film information related to the film can also be obtained using this identification method. Furthermore, film information includes various pieces of information related to this film. These include information about the film's manufacturer, product grade, whether it is single-layer or multi-layer, the film's intended use, the type of polyester, the content of each polyester, the film's composition, whether or not it contains recycled polyester, the type of recycled polyester, the recycled polyester content, and whether or not it has a functional layer. Therefore, when the film identified by this identification method is collected, recycled, and reused, the film information obtained above can be used to sort the collected polyester film by polyester type and product, and to select the recycling method.

[0083] Furthermore, as described above, by manufacturing this film with linked film information, it becomes possible to centrally manage usage by customers such as component manufacturers and final product manufacturers, as well as consumer usage and collection from customers or consumers. In particular, if tracking and understanding are possible at each stage of manufacturing, sales, collection, sorting, and recycling, it can be expected that not only further recycling but also manufacturing and sales can be carried out smoothly. As described above, the information about substance (A) or substance (A) and substance (B) linked to the film information of this film is called identifying element information. Identifying element information can be obtained, for example, by analyzing this film with an analytical device, as described later. It is preferable that the information includes information on at least one type of identifying element contained in this film (i.e., at least element (A) or element (A) and element (B)), but it is even more preferable that it includes information on the content (reference value) of each identifying element. It may also include information on identifying substances (composition and bonding state) containing the identifying elements mentioned above. The identifying element information and the film information linked to the identifying element information are collectively called tag information.

[0084] <How to use this film as a recycled material> In one embodiment, the present invention also provides a method for using the film as a recycled material. As described later, the film is processed as appropriate by component manufacturers, final product manufacturers, etc., as needed, and then consumed. After consumption, it is collected and sorted, and subsequently reused as a recycled material. The recycled material may be in any form, including polyester film. That is, after sorting, the film may be further reused as polyester film after the functional layer is removed as needed. Furthermore, after sorting, the film may be further processed as needed, removing the functional layer and being used as recycled polyester in a form that can be used as a raw material, such as powder, granules, pellets, or flakes. While it is preferable that these recycled polyesters be used again in films, they may also be used in molded products other than films, such as trays and bottles. When this film is used as recycled material, the film information (i.e., tag information) linked to the identifying element information can be used for sorting, sorting, and selecting recycling methods during recycling, thus enabling efficient recycling.

[0085] The following describes an example of using blockchain technology to utilize this film as a recycled material. While the following explanation uses the reuse of this film as an example, the film may be reused in other ways.

[0086] [blockchain] In one embodiment of the present invention, tag information is managed in a blockchain-based recycling system. By managing tag information on the system, the tag information of the film can be read at each stage from the manufacturing of the film to obtaining recycled materials. In other words, regardless of the process of the plastic product, the staff at each stage can access the tag information of the film. This tag information can then be used, for example, during recycling.

[0087] Figure 1 is an explanatory diagram showing an example of each step in the recycling system 1 according to this embodiment. In Figure 1, the film manufacturing step 12 is a step in which a polyester film (the main film) is manufactured. In the film manufacturing step 12, the polyester film may be manufactured from virgin polyester, from recycled polyester, or from both virgin polyester and recycled polyester. The method for manufacturing the polyester film in the film manufacturing step 12 is as described above. Furthermore, if a functional layer is to be provided in the main film, the film manufacturing step 12 may also include a step in which a functional layer is formed in the polyester film (primary processing step). In addition, the film manufacturing step 12 may also include a step in which polyester is manufactured from polyester raw materials (such as dicarboxylic acid components and diol components). The recycled polyester used in the film manufacturing process 12 may be recycled raw material obtained in the recycled raw material process 18 described later, or polyester film obtained by sorting in the sorting process 17 may be used. It may also be obtained from various polyester resin products or scraps generated during the production process.

[0088] The component manufacturing process 13 is a process for processing the main film into components. The components may be manufactured, for example, by layering the main film with another film, or by layering the main film with other films, or by adding another functional layer to the main film manufactured in manufacturing process 12, or by combining these.

[0089] The final product process 14 is the process of manufacturing a product to be provided to the end consumer using the components. For example, in the final product process 14, the components manufactured in the component process 13 are attached to or incorporated into the final product. However, the component process 13 and the final product process 14 may be omitted as appropriate, and the components manufactured in the component process 13 may be considered the final product, or the main film manufactured in the manufacturing process 12 may be considered the final product. Consumption process 15 is the process in which the final product is consumed by consumers. In consumption process 15, consumers include not only individuals but also corporations, as long as they consume the film. Therefore, for example, consumers include manufacturers who consume the film as process film in the manufacture of other products.

[0090] The recovery process 16 is a process of recovering the consumed final product. The sorting process 17 is a process of sorting the recovered final product. The sorting process 17 is a process of separating the main film from the final product. The separated main film may have a functional layer or other laminated on it, or it may have other polyester films or the like laminated on it. The recycling raw material process 18 is a process of obtaining recycled raw materials from the separated main film. The recycling raw material process includes steps such as removing other films from the separated main film and removing functional layers. It may also include a step of further processing the polyester film to obtain recycled raw materials such as polyester powder or polyester raw materials obtained by further chemically decomposing polyester. The recycling raw material process 18 may be omitted if the polyester film separated in the sorting process 17 can be used as recycled raw material as is. Once the recycled raw materials process 18 is complete, the process moves to the film manufacturing process 12, where recycled raw materials are used to produce more polyester film. From this point onward, the recycling system 1 can repeat the manufacturing process 12 through the recycled raw materials process 18.

[0091] (Blockchain system configuration) Figure 2 is a block diagram illustrating an example of a blockchain system configuration. In Figure 2, the blockchain 100 comprises a network 110, node servers 120 (120a to 120d), terminal devices 130 to 135, and a network 140. Network 110 is a P2P (Peer to Peer) network that enables communication between multiple computers. Although the diagram shows four node servers 120 for convenience, there are actually more than this number. The node servers 120 store tag information, which will be described later, and the server's tag information can be read and written from terminal devices 130 to 135. However, it is possible to restrict some terminal devices to read but not write.

[0092] Network 110 is composed of terminals called Peers (node ​​servers 120), for example. In this blockchain 100, there is no entity equivalent to a server in a client-server model, so even if a particular Peer disconnects, the provision of services does not stop. In this way, blockchain 100 can be said to be a "decentralized" system because each participant is on equal footing. Node server 120 can verify and reach an agreement on transactions using blockchain 100's consensus algorithm. Blockchain 100 stores a certain amount of transaction data (transactions) that occur within a certain time period within network 110 into blocks. The generated blocks are then added to the end of the most recent existing block and accumulated. As a result, the blocks are linked together in chronological order like a chain.

[0093] To explain in more detail, each block in Blockchain 100 contains transaction data, a hash value, and a nonce value. The hash value is an irregular string that can only be transformed in one direction, and it is obtained from the original data using an algorithm that employs a hash function. Only the same hash value can be obtained from the same transaction data. And, the transaction data of the previous block is always recorded as the hash value in each new block. The nonce value is a number that is used only once. The nonce value changes the hash value used in subsequent blocks. Therefore, if transaction data within a block generated at some point in the past were to be tampered with, the hash value obtained from that block would differ from the legitimate one. To tamper with it, the hash values ​​of all subsequent blocks would have to be changed. Changing hash values ​​in this way is virtually impossible. For this reason, Blockchain 100 has a structure that is highly resistant to tampering.

[0094] Each node server 120 stores its own tag information DB (database) 121 that stores tag information. Terminal devices 130 to 135 are connected to any node server 120 (in Figure 2, node server 120c) via a network 140 such as the internet. Terminal devices 130-135 are information processing devices operated by staff at each stage of the process. Terminal devices 130-135 have predetermined applications (information generation programs and recycling programs) installed. Using these predetermined applications, terminal devices 130-135 accept film information registration requests from staff. Terminal devices 130-135 are information processing devices that can connect to the network 140 via wired or wireless connection, such as personal computers, smartphones, and tablet devices. In the following, applications may be referred to as "apps."

[0095] Terminal device 130 is located in the manufacturing site where manufacturing process 12 takes place at the material manufacturer 150. Terminal device 131 is located in the manufacturing site where component process 13 takes place at the component manufacturer 151. Terminal device 132 is located in the manufacturing site where final product process 14 takes place at the final product manufacturer 152. Terminal device 133 is located in the work area where sorting process 17 takes place at the sorting company 153. Terminal device 134 is located in the work area where recycling material process 18 takes place at the recycled material manufacturer 154. Furthermore, if the final product is consumed by the manufacturer 155, terminal device 135 may also be installed at that manufacturer 155. For convenience, manufacturers 150, 151, 152, and 154, the separate company 153, and the manufacturer 155 are described as separate legal entities, but at least two of them may be the same legal entity. Also, terminal devices 130 to 135 may be located at different business locations or at the same location.

[0096] (Hardware configuration of terminal devices 130-135) Figure 3 is a block diagram showing an example of the hardware configuration of terminal devices 130 to 135. In Figure 3, terminal devices 130 to 135 include a CPU (Central Processing Unit) 301, memory 302, input device 303, analysis device 304, communication interface 305, storage medium interface 306, and display 307. Each of the components 301 to 307 is connected by a bus 320. The CPU 301 controls the entire terminal devices 130 to 132. The memory 302 includes, for example, ROM (Read Only Memory), RAM (Random Access Memory), and flash ROM. For example, the flash ROM and ROM store various programs. These programs include information generation programs and recycling programs according to this embodiment. The RAM is used as the work area of ​​the CPU 301. Programs stored in the memory 302 are loaded into the CPU 301, causing the CPU 301 to execute the coded processes. The input device 303 includes a touch panel, keyboard, mouse, microphone, etc.

[0097] The analysis device 304 is as described above. The communication interface 305 is connected to a network 140, such as the Internet, via a communication line, and is connected to other devices via the network 140. The communication interface 305 manages the interface between the network 140 and the inside of the device, and controls the input and output of data from other devices (for example, the node server 120 or other terminal devices 130-135). The communication interface 305 can be, for example, a modem or a LAN adapter. The storage medium interface 306 controls the reading and writing of data to storage media (not shown), such as magnetic disks and optical disks, according to the control of the CPU 301. Display 307 is an output device that displays images. In addition to display 307, terminal devices 130-135 may also be equipped with other output devices such as microphones and printers.

[0098] (An example of each process performed in Recycling System 1) Figure 4 is a flowchart of an example of each process performed in the recycling system 1. As shown in Figure 4, first, a product manufacturing process is carried out to produce a product containing the film with identification element information (step S401). The raw materials in the product manufacturing process include virgin polyester, recycled polyester, or both. The product manufacturing process may be carried out by a series of processes such as the film manufacturing process 12, component process 13, and final product process 14 described above, but any of these processes may be omitted as appropriate.

[0099] In the product manufacturing process, identification element information is introduced into the film. Specifically, in the film manufacturing process 12, identification element information is introduced into the film. That is, in manufacturing process 12, as described above, element (A), or element (A) and element (B) are blended as identification elements into the film, i.e., the polyester film, the functional layer, or both. The identification elements are blended at a predetermined content (i.e., a standard value) that is set in advance. Furthermore, material manufacturer 150 should, in addition to introducing the identification element information into the film, store the film information linked to the identification element information as tag information on a server.

[0100] Once the final product is completed, the product is distributed and the consumption process 15 takes place (step S402). When the product is used by the user and is no longer usable, the collection process 16 takes place (step S403). A sorting process 17 is performed to separate the polyester film from the collected final product, and a process is carried out to obtain recycled raw materials from the separated main film and polyester film (step S404). The recycled raw materials are then used again in the product manufacturing process of step S401. In this way, the recycling system 1 can repeat each of the processes from steps S401 to S405. Step S405 may be omitted, and the process of obtaining recycled raw materials may be performed in step S404. Furthermore, the identification element information introduced during the product manufacturing process can be circulated along with the film through the recycling system 1, which encompasses the manufacturing, consumption, collection, sorting, and reuse of the product.

[0101] Figure 5 is a block diagram showing an example of the functional configuration of a terminal device 130 used in the film manufacturing process 12. In Figure 5, the terminal device 130 comprises an input unit 901, a generation unit 902, a registration unit 903, an acquisition unit 904, and an output unit 905. Each unit 901 to 905 is implemented by the CPU 301. That is, the CPU 301 implements the functions of each unit 901 to 905 by executing an information generation program.

[0102] As described above, in the film manufacturing process 12, the identification element is incorporated to produce the main film with identification element information attached. The input unit 901 inputs the film information of the main film produced in the film manufacturing process 12. The input unit 901 inputs the film information received from the work staff by the input device 303. The generation unit 902 generates tag information that links the identification element information and the film information. The registration unit 903 registers the tag information. In this embodiment, the registration unit 903 registers the tag information with the node server 120 using a system that utilizes the blockchain 100. Note that the server to which the tag information is registered is not limited to the node server, but may be a server in a client-server system, etc. The output unit 905 outputs the tag information. Specifically, the output unit 905 sends the tag information to the node server 120 via the communication I / F 305, thereby writing the tag information to the server.

[0103] The acquisition unit 904 acquires the identification element information obtained by the analyzer 304. In the manufacturing process, the detection of identification element information is preferably performed automatically. Specifically, in the manufacturing process, the analyzer 304 is fixedly positioned on, for example, the factory line. For example, if the manufactured products are moved along the line, the analyzer 304 acquires the identification element information of the moving products. However, the analysis by the analyzer 304 may also be performed manually. The acquisition of identifying elemental information using the analytical instrument 304 should be performed on a per-product basis. A per-product basis refers to, for example, a product lot or a product type (model number). Alternatively, a per-product basis may refer to a single manufactured product unit. Furthermore, if, for example, the identifying element information for products manufactured using the same manufacturing process is known, or if average data of identifying element information has been accumulated, the analysis by the analytical device 304 may be omitted. In this case, the acquisition unit 904 only needs to acquire the identifying element information corresponding to the product from the accumulated data. Furthermore, the reading by the analyzer 304 may be performed until a certain amount of data is accumulated for the identification element information, and after a certain amount of data has been accumulated, the reading may be omitted by using the average of that data. The generation unit 902 generates tag information by associating the film information with the identification element information acquired by the acquisition unit 904.

[0104] Figure 6 is a block diagram showing an example of the functional configuration of a terminal device 134 used in the recycling raw material process 18. In Figure 6, the terminal device 134 comprises a first acquisition unit 1001, a second acquisition unit 1002, and an output unit 1003. Each unit 1001 to 1003 is implemented by a CPU 301. That is, the CPU 301 implements the functions of each unit 1001 to 1003 by executing a recycling program. The first acquisition unit 1001 analyzes the film, such as the main film, obtained by separating the product using the analysis device 30 to obtain analysis results regarding the identifying elements. The analysis results include, for example, the types of identifying elements (element (A), elements (A) and (B)), the content of each identifying element, and information about the identifying substance containing the identifying elements (composition of the bonding state). At the recycled raw material manufacturer 154, the detection of the analysis results may be performed automatically or manually, and the details are the same as described above.

[0105] The second acquisition unit 1002 acquires film information about the analyzed film based on the analysis results acquired by the first acquisition unit 1001. Specifically, the second acquisition unit 1002 requests the node server 120 to transmit tag information, which includes identification element information corresponding to the analysis results acquired by the first acquisition unit 1001. The transmission request includes analysis result information. When the node server 120 receives a transmission request from the terminal device 134, it searches for the identification element information with the highest similarity to the analysis result information included in the transmission request, and extracts tag information containing the identification element information corresponding to the search result. The node server 120 then transmits the extracted tag information to the terminal device 132. Furthermore, if the node server 120 does not have any identification element information similar to the analysis result information included in the transmission request, it sends a message to the terminal device 134 indicating that there is no tag information (null information). The second acquisition unit 1002 then receives tag information or null information from the node server 120. If the second acquisition unit 1002 receives tag information, it extracts film information from the tag information. The output unit 1003 outputs the film information acquired by the second acquisition unit 1002.

[0106] Then, the recycled material manufacturer 154 should carry out recycling based on the film information described above. Specifically, the separated films should be sorted by type and processed according to type to obtain recycled materials for each type. For example, if, based on the film information, the separated film is identified as a type "A" film with a specific composition that can be reused as is, it is sorted as type "A" film, and the functional layer is removed as needed, and film "A" is reused as recycled raw material. Furthermore, if a film of type "B" has a specific composition and cannot be reused as a film, it may be sorted as a film of type "B," and if necessary, the functional layer may be removed as appropriate, and the film may be processed by a physical recycling method to be used as a recycled resin in the form of a powder, granules, pellets, flakes, etc., which can be used as a raw material. Alternatively, the film may be recycled by a chemical recycling method to produce recycled resin. Furthermore, if the recycled raw material manufacturer 154 cannot obtain film information about the separated film (i.e., obtains null information), it can either discard the separated film or, if it can be reused after conducting a resin composition analysis, it can be reused.

[0107] Furthermore, as described above, if the film is reused as is (i.e., film "A"), the elements (A) or (A) and (B) will be reused as film while maintaining their respective content, and therefore, elements (A) or (A) and (B) will continue to be used as identifying elements. Furthermore, as indicated by film "B", when reused by physical or chemical recycling methods, element (A) or elements (A) and (B) may be incorporated into the film produced in film manufacturing process 12 together with the recycled polyester (i.e., while still incorporated into the recycled raw material). This allows element (A) or elements (A) and (B) to continue to be used as identifying elements. However, if the content of element (A) or elements (A) and (B) changes, elements (A) or elements (A) and (B) may be added during the film manufacturing process. Furthermore, element (A) or elements (A) and (B) used as identification elements may be removed in the recycling raw material process as appropriate, in which case elements (A) or elements (A) and (B) may be added to the film again in the film manufacturing process 12.

[0108] Furthermore, while the above description has typically illustrated a scenario in which a material manufacturer 150 creates identification element information from the film and writes it to a server, and a recycled material manufacturer 154 reads the tag information from the server based on the analysis results and uses the film information contained in the tag information to perform recycling, the recycling system is not limited to such a scenario. For example, a sorting company 153 could perform the same process as a recycled raw material manufacturer 154, analyze the film separated from the final product, and then read the film information from a server based on the analysis results for use during recycling.

[0109] Furthermore, component manufacturer 151, final product manufacturer 152, and manufacturer 155 can also analyze the film using the same analytical device 304 and, based on the analysis results, obtain film information from the server by performing the same operations as those performed by the recycled raw material manufacturer 154. As a result, component manufacturer 151 and final product manufacturer 152 can obtain recycling information such as whether the film contains recycled polyester and the recycled polyester content in the film using the acquired film information. Based on this recycling information, they can certify that components and final products are recycled products or display the recycling rate. In addition, component manufacturer 151 and final product manufacturer 152 can also obtain film information other than recycling information, such as film composition, and can utilize this film information for components and final products. Similarly, manufacturers (consumers) can use the acquired film information to confirm that they are using products with a low environmental impact, such as whether the film contains recycled polyester and information on recycling, including the percentage of recycled polyester in the film. This information can also be used to obtain environmental certifications for their own companies.

[0110] Furthermore, while the above explanation assumes that the polyester raw material used in the film manufacturing process may be either virgin polyester or recycled polyester, it is preferable to include recycled polyester. By including recycled polyester, element (A) or elements (A) and (B) can be used as identifying elements to indicate the presence of recycled polyester or the recycled polyester content. Therefore, companies involved in the production and reuse of this film (e.g., material manufacturers, component manufacturers, final product manufacturers, manufacturers, recycled raw material manufacturers, etc.) can share recycling information, making it easier to establish a more effective recycling system.

[0111] The above explanation uses the example of a molded product being a recycled polyester film, but the same applies to molded products other than films. Specifically, even in cases other than films, the molded product is a polyester molded product in which polyester is the main component resin, and the details of the polyester used in polyester molded products are as described above, and the physical properties of the molded product are as described in the physical properties of the film. Furthermore, the details of elements (A) and (B) and their content are as described above. In addition, the molded product may consist of a polyester molded product alone, or a functional layer may be laminated to the polyester molded product as appropriate. In this case, the functional layer may contain elements (A), elements (B), or both as appropriate. Furthermore, even if the molded product is not this film, the method for identifying the molded product and the method for using it as recycled material are the same as those described for this film. In addition, when using the molded product as recycled material, blockchain may be used, along with information about the molded product as appropriate. Information about the molded product should be used in the same way as the film information described above. [Explanation of Symbols]

[0112] 1. Recycling System 100 Blockchains 120-node server 121 Tag Information Database 130-135 Factory terminal equipment 301 CPU 302 memory 303 Input Devices 304 Analyzer 305 Communication I / F 307 display 901 Input section 902 Generation part 903 Registration Department 904 Acquisition Department 905 Output section 1001 First Acquisition Department 1002 Second Acquisition Department 1003 Output section

Claims

1. A recycled polyester molded article containing at least one element (A) selected from the group consisting of Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, Nb, Ca, Mn, S, Cr, Cu, Zn, and Co, in an amount of 0.1 ppm by mass or more and 5000 ppm by mass or less.

2. A recycled polyester molded article according to claim 1, which is a film.

3. The recycled polyester molded article according to claim 1, wherein the element (A) comprises at least one selected from the group consisting of Al, Mg, Ge, Sc, Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb.

4. The recycled polyester molded article according to claim 1, wherein the element (A) comprises at least one selected from the group consisting of Al, Mg, Ge, and Sc.

5. The recycled polyester molded article according to claim 1, wherein element (A) consists of two or more elements.

6. The recycled polyester molded article according to claim 1, wherein the element (A) comprises at least one element (A1) selected from the group consisting of Al, Mg, Ge, and Sc, and at least one element (A2) selected from the group consisting of Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb.

7. The recycled polyester molded article according to claim 1, wherein the element (A) comprises at least one element (A1) selected from the group consisting of Al, Mg, Ge, and Sc, and at least one element (A3) selected from the group consisting of Ca, Mn, S, Cr, Cu, Zn, and Co.

8. The recycled polyester molded article according to claim 1, wherein the element (A) comprises at least one element (A2) selected from the group consisting of Si, Fe, P, Rb, Ba, Zr, Sr, Ni, Sb, and Nb, and at least one element (A3) selected from the group consisting of Ca, Mn, S, Cr, Cu, Zn, and Co.

9. The recycled polyester molded article according to claim 1, comprising a metal element nanocomposite containing the aforementioned element (A).

10. The recycled polyester molded article according to claim 1, wherein the intrinsic viscosity of the polyester contained in the recycled polyester molded article is 0.5 dL / g or more and 0.7 dL / g or less.

11. Volume resistivity is 1.0 × 10⁻⁶ ７ Ω・cm or more 1.0×10 ９ A recycled polyester molded article according to claim 1, wherein the density is Ω·cm or less.

12. The recycled polyester molded article according to claim 1, wherein the carboxyl group concentration is 25 eq / ton or more and 60 eq / ton or less.

13. The recycled polyester molded article according to claim 1, wherein the content of ester cyclic trimers is 10,000 ppm by mass or less.

14. The recycled polyester molded article according to claim 1, wherein the content of diethylene glycol in the total diol components of the polyester contained in the recycled polyester molded article is 5 mol% or less.

15. A recycled polyester molded article according to claim 1, comprising a multilayer film having an intermediate layer and surface layers on both sides of the intermediate layer, wherein the intermediate layer contains the element (A).

16. A recycled polyester molded article according to claim 1, wherein the film is biaxially oriented.

17. The recycled polyester molded article according to claim 1, wherein the element (A) is detectable by X-ray fluorescence analysis (XRF).

18. A method for identifying a recycled polyester molded product, comprising analyzing a recycled polyester molded product according to any one of claims 1 to 17, and identifying the recycled polyester molded product based on the type of element (A) detected in the recycled polyester molded product.

19. A method for identifying a recycled polyester molded product, comprising analyzing a recycled polyester molded product according to any one of claims 1 to 17, and identifying the recycled polyester molded product based on the type and content of element (A) detected in the recycled polyester molded product.

20. A method for using a recycled polyester molded article according to any one of claims 1 to 17 as a recycled raw material.

21. The method according to claim 20, which utilizes blockchain.

22. The aforementioned blockchain comprises a network, a server, and multiple terminal devices. Tag information is stored on the aforementioned server. The method according to claim 21, wherein the tag information includes information of at least one type of element (A) and information relating to the polyester molded article associated with said information.

23. The method according to claim 22, wherein the tag information is read and used when recycling the recycled polyester molded product.

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