Removal method and manufacturing method of recycled film

Abstract

A removal method capable of removing a functional layer from a film containing the functional layer with high precision, and a method for producing a recycled film using the removal method are provided. A removal method for removing a functional layer from a film including the functional layer includes the steps of processing the film by irradiating the functional layer with high-energy radiation and removing the functional layer from the processed film.

Description

[Technical Field]

[0001] The present invention relates to a removal method and a method for producing recycled film. [Background technology]

[0002] Japanese Patent No. 6849141 (Patent Document 1) discloses a method for producing a heat-shrinkable film. This heat-shrinkable film is produced using a resin composition containing at least one of fluff and re-pellets obtained from packaging material as a starting material. The packaging material, which is the starting material for the fluff and re-pellets, has a printed layer (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6849141 Summary of the Invention [Problem to be solved by the invention]

[0004] Many film products have functional layers such as printed layers. Therefore, much of the waste film also contains foreign matter such as colorants. When recycled film is produced using waste film, the foreign matter contained in the waste film affects the quality of the recycled film. In order to reduce the impact of the foreign matter contained in the waste film on the quality of the recycled film, it is possible to remove the functional layer from the waste film in advance. However, it is not necessarily easy to remove the functional layer with high precision. Patent Document 1 does not disclose a means for solving this problem.

[0005] The present invention has been made to solve such problems, and its purpose is to provide a removal method that can remove a functional layer from a film that includes a functional layer with relatively high precision, and a method for manufacturing recycled film using this removal method. [Means for solving the problem]

[0006] A method for removing a functional layer from a film including the functional layer according to one aspect of the present invention includes the steps of processing the film by irradiating the functional layer with high-energy radiation and removing the functional layer from the processed film.

[0007] According to this removal method, the functional layer is irradiated with high-energy rays, which makes it easier to remove the functional layer, and therefore the functional layer can be removed from the film with higher precision.

[0008] In this removal method, the step of removing the functional layer may include the step of removing the functional layer by using a desorption liquid.

[0009] According to this removal method, the functional layer is irradiated with high-energy rays, which makes it easier for the release liquid to penetrate into the interface between the functional layer and the film body, thereby enabling the functional layer to be removed from the film with higher precision.

[0010] In this removal method, the release liquid may be an alkaline solution, and the pH of the alkaline solution may be 8 or more and 11 or less.

[0011] According to this removal method, the functional layer is irradiated with high-energy rays, which makes it easier for the alkaline solution to penetrate into the interface between the functional layer and the film body, so that the functional layer can be removed from the film with greater precision even if the alkaline solution is a weak alkaline solution.

[0012] In this removal method, the step of removing the functional layer may include the step of removing the functional layer by subjecting the functional layer to a physical treatment.

[0013] According to this removal method, the functional layer is irradiated with high-energy rays, which makes it easier to perform physical processing at the interface between the functional layer and the film body, allowing the functional layer to be removed from the film with greater precision.

[0014] In this removal method, the step of removing the functional layer may include the step of washing the film.

[0015] This removal method involves cleaning the film, so that debris remaining on the film, for example from the functional layer, can be washed away.

[0016] In this removal method, the film may include a first region where a functional layer is laminated and a second region where no functional layer is laminated, and in the processing step, high-energy rays may be irradiated to the first region but not to the second region.

[0017] According to this removal method, the high-energy beam is not irradiated onto the second region, and therefore the time required for film processing can be shortened compared to when high-energy beams are irradiated onto both the first and second regions.

[0018] A method for producing a recycled film according to another aspect of the present invention includes the steps of producing a film from which the functional layer has been removed by using the above-mentioned removal method, and producing a recycled film by using the film from which the functional layer has been removed.

[0019] According to this method for producing recycled films, recycled films are produced based on films from which the functional layer has been removed with high precision, making it possible to produce recycled films of higher quality. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a removal method that can remove a functional layer from a film that includes a functional layer with relatively high precision, and a method for producing a recycled film using the removal method. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a resource circulation system. [Figure 2] FIG. 1 is a plan view schematically showing an example of a printed film. [Figure 3] FIG. 3 is a diagram schematically showing a cross section taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is a diagram schematically illustrating a portion of the front of the printing layer removing device. [Figure 5] 1 is a flowchart showing an example of a manufacturing procedure for a recycled film. [Figure 6] 6 is a flowchart showing an example of a processing procedure performed in step S100 of FIG. 5. [Figure 7] FIG. 2 is a diagram schematically illustrating a cross section of an example of a recycled film to be produced. [Figure 8] FIG. 10 is a plan view schematically showing another example of a printed film. [Figure 9] 10 is a flowchart showing an example of a procedure for irradiating high-energy rays by an irradiation device. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described in detail below with reference to the drawings. Note that the same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated. Furthermore, for ease of understanding, each drawing is drawn schematically with objects appropriately omitted or exaggerated.

[0023] [1. Structure of the resource recycling system] In recent years, marine pollution caused by plastic waste has become a global problem, and resource recycling has been attracting attention as a means of addressing this issue.

[0024] FIG. 1 is a diagram schematically illustrating the configuration of a resource circulation system S1 that uses a recycled film manufacturing method according to the present embodiment. Referring to FIG. 1, in the resource circulation system S1, for example, a resin film printed with a design (hereinafter also referred to as "printed film") is recycled to produce new film. The design may be, for example, a pattern, letters, a symbol (e.g., a barcode), or a combination thereof. The printed film is a packaging material such as a heat-shrinkable film or label that can be used for, for example, food, beverages, pharmaceuticals, medical supplies, cosmetics, toiletries, or industrial and agricultural products. The following describes the recycling of waste heat-shrinkable film, a typical type of printed film.

[0025] FIG. 2 is a plan view schematically illustrating an example of a printed film. In this example, the printed film 40 is a heat-shrinkable film having a printed layer and in a state before heat shrinkage. The printed film 40 is a long film having a width direction and a length direction. The printed film 40 is stored in a roll form for storage and handling reasons. The printed film 40 may be heat-shrunk primarily in a uniaxial direction (width direction) for use as, for example, a cylindrical label. The heat shrinkage rate (main shrinkage direction) of the resin layer 42 (see FIG. 3) is appropriately selected taking into consideration the ease of attachment to a container or the like when used as a label. For example, when immersed in hot water at 90°C for 10 seconds, the heat shrinkage rate is preferably 30% or more, and more preferably 50% or more. As shown in FIG. 2, the printed film 40 includes a product portion 400 and edge portions 410A and 410B. The edge portions 410 are provided adjacent to both ends of the product portion 400 in the width direction. A design is printed on each of the product portion 400 and the edge portion 410. Printing on the film is performed, for example, by using a gravure printing plate.

[0026] Product portion 400 is used for packaging plastic containers, glass containers, paper containers, etc. Information, etc. for checking the printing status of product portion 400 is printed on each of edge portions 410A, 410B. Edge portions 410 are cut and wound up before product portion 400 is shipped. In this way, a roll of product portion 400 and edge portions 410 is formed.

[0027] The printed film (product portion 400) with a design printed thereon is attached to the outer periphery of the body of a container as a label. Methods for attaching the film to a container include, for example, wrapping the label around the container, and forming a tubular label (hereinafter also referred to as a "tubular label") by bonding both ends of the printed film together with the side bearing the design facing inward, and then covering the container with the tubular label and heat-shrinking the tubular label to adhere the label to the outer periphery of the body of the container. A tubular label is manufactured, for example, by the following method: A long, printed film is slit to the width of the design, a solvent or the like is applied to one end of the printed film in the width direction, and the one end and the other end are overlapped and bonded together (center-sealed), thereby obtaining a long, tubular label. The long, tubular label is cut to obtain a single tubular label, which is then attached to a container.

[0028] FIG. 3 is a schematic diagram showing the cross section taken along the line III-III in FIG. 2. As shown in FIG. 3, the printed film 40 includes a resin layer 42 and a printing layer 44. In this example, the resin layer 42 is a heat-shrinkable film. The printing layer 44 is composed of a coloring component (colorant), such as ink, that forms a pattern. In this example, the object to be packaged is placed on the side of the printing layer 44. That is, when packaging is performed using the printed film 40, the printing layer 44 is located on the inner side. The printing layer 44 may be a single layer or a multilayer. The thickness of the printing layer 44 is appropriately selected depending on the application, and may be, for example, approximately 0.1 to 20 μm. An inner coat layer may be provided on the printing layer 44, and an overcoat layer may be provided on the resin layer 42 (the side opposite the printing layer 44). The inner coat layer is formed, for example, to improve the slipperiness of the inner surface of the cylindrical label between the object to be packaged and the attachment device. The overcoat layer is formed, for example, to reduce scratches on the outer surface of the label. The inner coat layer and the over coat layer are each formed, for example, in a pattern printing process. The print layer 44, the inner coat layer, and the over coat layer are each included in the "functional layer" of the present invention.

[0029] The resin layer 42 may be composed of a single layer or multiple laminated layers. The resin layer 42 may include a layer containing a mixture of different resins, or multiple layers each containing a different type of resin. The overall thickness of the resin layer 42 can be selected appropriately depending on the application, but is preferably 10 μm to 60 μm, more preferably 12 μm to 50 μm, and even more preferably 15 μm to 35 μm. When the thickness of the resin layer 42 is within the above range, excellent heat shrinkability, excellent converting properties such as printing and center sealing, and excellent wearability can be obtained. Furthermore, each layer constituting the resin layer 42 may contain components other than resin. Each layer may contain metal components such as aluminum, antiblocking agents, additives, etc. Examples of additives include heat stabilizers, antioxidants, UV absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, and fluorescent brighteners.

[0030] Examples of the resin contained in each layer include polyolefin-based resins, polystyrene-based resins, polyamide-based resins, and polyester-based resins. Examples of polyolefin-based resins include polypropylene-based, polyethylene-based, and cyclic polyolefin-based resins. Examples of polypropylene-based resins include binary or ternary random copolymers containing propylene as the main component and ethylene, butene, or an α-olefin as a copolymerization component. Specific examples of α-olefins include those composed of ethylene, 1-butene, 1-hexene, 1-octene, etc., and may contain two or more types of α-olefins. Furthermore, the polypropylene-based resin may be a mixture of different propylene-α-olefin random copolymers. Examples of polyethylene-based resins include branched low-density polyethylene resins, linear low-density polyethylene resins, high-density polyethylene resins, ethylene-vinyl acetate copolymers, ionomer resins, and mixtures thereof. Furthermore, copolymers of ethylene and α-olefins are also included. Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The copolymers may be random copolymers or block copolymers. Examples of cyclic olefin resins include (a) copolymers of ethylene or propylene with cyclic olefins (e.g., norbornene and its derivatives, tetracyclododecene and its derivatives, etc.), (b) ring-opening polymers of the cyclic olefins or copolymers with α-olefins, (c) hydrogenated products of the polymers (b), and (d) graft-modified products of the above (a) to (c) with unsaturated carboxylic acids and their derivatives, etc. The cyclic olefin is not particularly limited, and specific examples thereof include norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, and 5-benzylnorbornene.Examples of polystyrene-based resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers with other monomers (conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Specific examples include aromatic vinyl hydrocarbon-conjugated diene copolymers, mixed resins of aromatic vinyl hydrocarbon-conjugated diene copolymers and aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymers, and rubber-modified impact-resistant polystyrene. More specific examples include styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), and hyperbranched polystyrene. Examples of polyamide-based resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the aliphatic polyamide include aliphatic nylon and its copolymers, such as polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), polyhexamethylenesebacamide (nylon-6,10), polyhexamethylenedodecamide (nylon-6,12), polyoctamethyleneadipamide (nylon-8,6), and polydecamethyleneadipamide (nylon-10,8). Examples of polyester resins include those obtained by condensation polymerization of a dicarboxylic acid component and a diol component. The type of the dicarboxylic acid component is not particularly limited, and examples include terephthalic acid, o-phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octylsuccinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylenecarboxylic acid, anhydrides thereof, and lower alkyl esters thereof.The type of the diol component is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5- Examples include aliphatic diols such as hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, and polytetramethylene ether glycol; and alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

[0031] Referring again to FIG. 1 , the resource circulation system S1 includes a printed layer removal device 10, a resin raw material manufacturing device 20, and a film manufacturing device 30. The printed layer removal device 10 is configured to remove printed layers from, for example, unused printed film or labels, edge portions cut from printed film and collected in roll form, or waste printed film generated during the manufacturing process of test print films. When removing the printed layer from a tubular label, it is desirable to open the tubular label into a film shape by peeling off the center seal beforehand to efficiently remove the printed layer. The history of the printed film from which the printed layer is removed by the printed layer removal device 10 is not particularly limited and may be, for example, unused, intermediately processed, leftover, defective, prototype, discarded, etc. The printed layer removal device 10 removes, for example, the printed layer 44, inner coat layer, and overcoat layer (hereinafter also referred to as "printed layer 44, etc.") from the printed film 40. The printed layer removal device 10 will be described in detail later.

[0032] The resin raw material manufacturing apparatus 20 is configured to manufacture a resin raw material using the printed film 40 from which the printed layer 44 and the like have been removed in the printed layer removing apparatus 10. The film manufacturing apparatus 30 is configured to manufacture a film by using the resin raw material manufactured by the resin raw material manufacturing apparatus 20.

[0033] Fig. 4 is a diagram schematically illustrating a portion of the front of the printed layer removal apparatus 10. Referring to Fig. 4, in the printed layer removal apparatus 10, for example, a printed film 40 is transported from a payout roll (not shown) toward a take-up roll. The printed layer removal apparatus 10 includes an irradiation device 100, a spraying device 110, a polishing device 120, a cleaning device 130, and a drying device 140. In the printed layer removal apparatus 10, the irradiation device 100, the spraying device 110, the polishing device 120, the cleaning device 130, and the drying device 140 are arranged in this order from upstream to downstream of the transport path of the printed film 40.

[0034] The irradiation device 100 is configured to process the surface of the printed film 40 by irradiating at least one side (one or both sides) of the printed film 40 with high-energy rays (also referred to as "active energy rays"). The high-energy rays are irradiated, for example, onto the surface on which the printed layer 44 is laminated. An example of a high-energy ray is ultraviolet light. Examples of sources of ultraviolet light include high-pressure mercury lamps, medium-pressure mercury lamps, xenon lamps, deuterium lamps, argon lamps, metal vapor lasers, excimer lasers, argon lasers, and ultraviolet light-emitting LEDs (Light Emitting Diodes). Note that the high-energy rays do not necessarily have to be ultraviolet light, and may be, for example, electron beams or radiation.

[0035] The irradiation device 100 irradiates the printed film 40 with high-energy rays, for example, so that damage extending in the transverse direction (TD) is formed at predetermined intervals in the machine direction (MD). The irradiation device 100 may irradiate the printed film 40 with high-energy rays, for example, so that damage extending in the MD is formed at predetermined intervals in the TD, or may irradiate the printed film 40 with high-energy rays so that damage extending in a direction tilted relative to the TD is formed at predetermined intervals in the MD. It is preferable that the damage occurring in the printed film 40 reaches near the interface between the resin layer 42 and the printing layer 44 in the thickness direction of the printed film 40, for example.

[0036] The spraying device 110 is configured to spray an alkaline solution onto at least one surface of the printed film 40 (for example, the surface irradiated with high-energy rays). The alkaline solution reacts with the ink, etc., causing the printed layer 44 to peel off from the resin layer 42. Specifically, the alkaline groups of the alkaline solution bond with the functional groups of the resin contained in the ink, inhibiting adhesion between the resin layer 42 and the ink, and as a result, the ink is detached from the resin layer 42.

[0037] By irradiating the printed layer 44 with high-energy rays before the alkaline solution is sprayed, scratches that reach the resin layer 42 are formed in the printed layer 44 at the stage when the alkaline solution is sprayed. This allows the alkaline solution sprayed onto the printed layer 44 to easily reach the interface between the resin layer 42 and the printed layer 44, allowing the printed layer 44 to be relatively easily peeled off from the resin layer 42. The alkaline solution sprayed by the spraying device 110 can be, for example, water containing an inorganic base. Specific examples of inorganic bases include sodium hydroxide and potassium hydroxide. These inorganic bases are preferably contained at a concentration of 0.1 to 10 mass% relative to the total amount of the alkaline solution. The pH of the alkaline solution should be greater than 7. However, considering the ease of disposal of waste liquid generated by spraying the alkaline solution, a pH of 7 to 11 is preferred, and a pH of 8 to 11 is even more preferred.

[0038] The polishing device 120 is configured to physically polish at least one surface of the printed film 40. By polishing with the polishing device 120, any printed layer 44 that was not completely removed by the spraying device 110 is removed from the printed film 40. The polishing device 120 includes, for example, a metal file or a polishing roll (physical processing unit). The printed film 40 is transported with the physical processing unit in contact with the printed layer 44 of the printed film 40, thereby removing the printed layer 44 from the printed film 40. The removed debris of the printed layer 44 generated during this process is sucked up, for example, by a suction mechanism (not shown), and collected for disposal.

[0039] The cleaning device 130 is configured, for example, to spray a cleaning liquid such as water onto at least one surface of the printed film 40. This washes away any removed debris remaining on the printed film 40. The drying device 140 is configured, for example, to blow warm air onto at least one surface of the printed film 40. This dries the surface of the printed film 40.

[0040] When both sides of the printed film 40 are treated in each of the irradiation device 100, the spraying device 110, and the polishing device 120, for example, if an overcoat layer is formed on the printed film 40, both the printed layer 44 and the overcoat layer can be removed from the printed film 40. The overcoat layer may contain a (meth)acrylic acid ester resin that can cause a decrease in haze in the recycled film, but this method makes it possible to remove the overcoat layer along with the printed layer 44, thereby reducing this effect.

[0041] In this way, according to the printing layer removal device 10, the printing layer 44 of the printed film 40 is irradiated with high-energy rays, making it easier to remove the printing layer 44, and therefore the printing layer 44 can be removed from the printed film 40 with greater precision.

[0042] In addition, according to the printing layer removal device 10, the printing layer 44 is irradiated with high-energy rays, which makes it easier for the alkaline solution to penetrate into the interface between the printing layer 44 and the resin layer 42, so that the printing layer 44 can be removed from the printed film 40 with greater precision even if the alkaline solution is a weak alkaline solution.

[0043] Referring again to Figure 1, the recycled film produced by film production apparatus 30 is printed again. That is, printed film 40 is produced again. A portion of the produced printed film 40 is again input into resource circulation system S1. Resource circulation is achieved by repeating this cycle.

[0044] [2.Recycled film manufacturing procedure] FIG. 5 is a flowchart showing an example of a manufacturing procedure for recycled film. Each step shown in this flowchart begins when waste film is collected. The waste film may include various types of film with various types of printing. Note that the waste film does not necessarily have to include various types of film with various types of printing, and may include, for example, only one type of film. For example, only one specific type of film may be recycled as waste film from waste material collected from a factory, etc.

[0045] 5, the collected waste film is subjected to a process for removing the printed layer (step S100). In step S100, for example, chemical removal using an alkaline solution and physical removal using mechanical actions such as rubbing, scraping, or peeling are performed.

[0046] FIG. 6 is a flowchart showing an example of the processing procedure performed in step S100 of FIG. 5. Referring to FIG. 6, the irradiation device 100 irradiates the collected waste film with high-energy rays (step S200). The spraying device 110 sprays an alkaline solution onto the printed film 40 that has been irradiated with the high-energy rays, thereby subjecting the printed film 40 to a chemical removal process (step S210). After the chemical removal process (chemical deinking process), the polishing device 120 subjects the printed film 40 to a physical removal process (physical deinking process) (step S220). Thereafter, the cleaning device 130 cleans the printed film 40 (step S230), and the drying device 140 dries the printed film 40 (step S240). This completes the printed film 40 from which the printing layer 44 has been removed.

[0047] Referring again to FIG. 5, when the removal of the printed layer is completed in step S100, the recycled raw material is produced by granulating the waste film after the removal of the printed layer (step S110). Step S110 is performed, for example, by the resin raw material manufacturing apparatus 20. The resin raw material manufacturing apparatus 20 can be realized, for example, by various known devices capable of granulating waste film. In step S110, the waste film after the removal of the printed layer is processed into granules. Examples of granulation methods include melt granulation and compression granulation. In melt granulation, the melt-kneaded waste film is extruded, and the extruded waste film is water-cooled and cut at the die outlet, thereby processing the waste film into granules. In compression granulation, the waste film is compression-molded, thereby processing the waste film into granules. In step S110, additives (e.g., heat stabilizers, antioxidants, UV absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, fluorescent brighteners, virgin raw materials, antiblocking agents) may be added to the waste film. Granulation in step S110 increases the bulk density of the waste film, thereby reducing the space required for storing the waste film.

[0048] After the recycled raw material is produced in step S110, a film forming process for a recycled film is performed by film production apparatus 30 (step S120). Note that the resin raw material used to produce the recycled film may also include biomass-derived raw materials or chemically recycled raw materials.

[0049] [3. Examples of recycled film] FIG. 7 is a schematic diagram showing a cross section of an example of a manufactured recycled film. As shown in FIG. 7, recycled film 50 includes intermediate layer 52 and adjacent layers 51 and 53. In recycled film 50, intermediate layer 52 is sandwiched between adjacent layers 51 and 53. In recycled film 50, intermediate layer 52 is made of a resin material containing virgin materials and recycled materials. Each of adjacent layers 51 and 53 is made of virgin materials. Each of adjacent layers 51 and 53 does not contain recycled materials. An adhesive layer may be provided between intermediate layer 52 and adjacent layers 51 and 53.

[0050] Examples of resins constituting the virgin raw materials contained in each layer include polyolefin-based resins, polystyrene-based resins, polyamide-based resins, and polyester-based resins. Examples of polyolefin-based resins include polypropylene-based, polyethylene-based, and cyclic polyolefin-based resins. Examples of polypropylene-based resins include binary or ternary random copolymers containing propylene as the main component and ethylene, butene, or an α-olefin as a copolymerization component. Specific examples of α-olefins include those composed of ethylene, 1-butene, 1-hexene, 1-octene, etc., and may contain two or more types of α-olefins. Furthermore, the polypropylene-based resin may be a mixture of different propylene-α-olefin random copolymers. Examples of polyethylene-based resins include branched low-density polyethylene resins, linear low-density polyethylene resins, high-density polyethylene resins, ethylene-vinyl acetate copolymers, ionomer resins, and mixtures thereof. Furthermore, copolymers of ethylene and α-olefins may be used. Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The copolymers may be random copolymers or block copolymers. Examples of cyclic olefin resins include (a) copolymers of ethylene or propylene with cyclic olefins (e.g., norbornene and its derivatives, tetracyclododecene and its derivatives, etc.), (b) ring-opening polymers of the cyclic olefins or copolymers with α-olefins, (c) hydrogenated products of the polymers (b), and (d) graft-modified products of the above (a) to (c) with unsaturated carboxylic acids and their derivatives, etc. The cyclic olefin is not particularly limited, and specific examples thereof include norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, and 5-benzylnorbornene.Examples of polystyrene-based resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers with other monomers (conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Specific examples include aromatic vinyl hydrocarbon-conjugated diene copolymers, mixed resins of aromatic vinyl hydrocarbon-conjugated diene copolymers and aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymers, and rubber-modified impact-resistant polystyrene. More specific examples include styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), and hyperbranched polystyrene. Examples of polyamide-based resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the aliphatic polyamide include aliphatic nylon and its copolymers, such as polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), polyhexamethylenesebacamide (nylon-6,10), polyhexamethylenedodecamide (nylon-6,12), polyoctamethyleneadipamide (nylon-8,6), and polydecamethyleneadipamide (nylon-10,8). Examples of polyester resins include those obtained by condensation polymerization of a dicarboxylic acid component and a diol component. The type of the dicarboxylic acid component is not particularly limited, and examples include terephthalic acid, o-phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octylsuccinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylenecarboxylic acid, anhydrides thereof, and lower alkyl esters thereof.The type of the diol component is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5- Examples include aliphatic diols such as hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, and polytetramethylene ether glycol; and alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

[0051] [4. Features] As described above, according to the printing layer removal device 10 of this embodiment, the printing layer 44 of the printed film 40 is irradiated with high-energy rays, making it easier to remove the printing layer 44, and therefore the printing layer 44 can be removed from the printed film 40 with greater precision.

[0052] In addition, according to the printing layer removal device 10, the printing layer 44 is irradiated with high-energy rays, which makes it easier for the alkaline solution to penetrate into the interface between the printing layer 44 and the resin layer 42, so that the printing layer 44 can be removed from the printed film 40 with greater precision even if the alkaline solution is a weak alkaline solution.

[0053] In addition, according to the printing layer removal device 10, high-energy rays are irradiated onto the printing layer 44, making it easier to perform physical processing on the printing layer 44 and the interface between the printing layer 44 and the resin layer 42, thereby allowing the printing layer 44 to be removed from the film with greater precision.

[0054] 5. Other Embodiments The concept of the above embodiment is not limited to the embodiment described above. Hereinafter, examples of other embodiments to which the concept of the above embodiment can be applied will be described.

[0055] <5-1> In the above embodiment, no particular consideration was given to whether the position of the high-energy beam irradiated by the irradiation device 100 is a position on the printed film 40 where the printed layer 44 is formed. However, the position of the high-energy beam irradiated by the irradiation device 100 may also be given to whether the position of the printed film 40 is a position on the printed film 40 where the printed layer 44 is formed.

[0056] FIG. 8 is a plan view schematically illustrating another example of a printed film. As shown in FIG. 8, the printed film 40X includes a product portion 400X and edge portions 410AX and 410BX. The edge portions 410X are located adjacent to both ends of the product portion 400X in the width direction. A design is printed on each of the product portion 400X and edge portions 410X. The product portion 400X includes a first region P1 and a second region P2. The first region P1 is a region where a printed layer is laminated, and the second region P2 is a region where no printed layer is laminated. For example, the irradiation device 100 may irradiate the first region P1 with high-energy radiation but not the second region P2 with high-energy radiation. This reduces the time required for film processing compared to when high-energy radiation is irradiated to both the first region P1 and the second region P2.

[0057] FIG. 9 is a flowchart showing an example of a procedure for irradiating high-energy rays by the irradiation device 100. Referring to FIG. 9, the irradiation device 100 determines whether a printed layer is stacked at the position where the high-energy rays are to be irradiated (step S300). This determination is made, for example, by a controller included in the irradiation device 100, by referring to the detection results of a sensor included in the irradiation device 100 (e.g., a sensor that detects light transmittance). If it is determined that a printed layer is stacked at the position where the high-energy rays are to be irradiated (YES in step S300), the irradiation device 100 irradiates the printed film 40 with high-energy rays (step S310). On the other hand, if it is determined that a printed layer is not stacked at the position where the high-energy rays are to be irradiated (NO in step S300), the irradiation device 100 does not irradiate the printed film 40 with high-energy rays (step S320). This shortens the time required for film processing compared to when the first region P1 and the second region P2 are irradiated with high-energy rays.

[0058] <5-2> Furthermore, in the above embodiment, the printing layer removal apparatus 10 performed both a chemical removal treatment and a physical removal treatment on the printed film 40. However, the printing layer removal apparatus 10 does not necessarily have to perform both a chemical removal treatment and a physical removal treatment on the printed film 40. For example, the printing layer removal apparatus 10 may simply perform at least one of a chemical removal treatment and a physical removal treatment on the printed film 40. Furthermore, the printing layer removal apparatus 10 does not necessarily have to wash and dry the printed film 40.

[0059] <5-3> In the above embodiment, the polishing device 120 may be replaced with, or used in combination with, a blasting device, a metal rotary brush, a rotary blade, a scraper, a belt sander, etc. In the above embodiment, the polishing device 120 and the cleaning device 130 may be replaced with, for example, a wet blasting device, a high-pressure cleaning device, etc.

[0060] <5-4> Furthermore, in the above embodiment, the printed film 40 is transported roll-to-roll. However, the printed film 40 does not necessarily have to be transported roll-to-roll. The printed film 40 may be, for example, in a sheet state, and each sheet of printed film 40 may be transported from upstream to downstream by a transport device such as a belt conveyor. The printed film 40 may also be pulverized into fluff. In this case, the fluff-like printed film 40 is irradiated with high-energy rays, and then, for example, an alkaline solution is sprayed on the pulverized printed film 40 or the pulverized printed film 40 is immersed in an alkaline solution.

[0061] <5-5> Furthermore, in the above embodiment, an alkaline solution was used to remove the printed layer 44 from the resin layer 42. However, a surfactant, an alcohol-based solvent, or the like may also be used as a release liquid for the printed layer. When a surfactant is used as a release liquid, the lipophilic groups of the surfactant are adsorbed to the oily components of the ink in the printed layer 44, and the hydrophilic groups of the surfactant exert a force that causes the ink to disperse in water, thereby removing the ink. The surfactant is not particularly limited, and known surfactants can be used, including, for example, anionic surfactants, nonionic surfactants, amphoteric surfactants, and cationic surfactants. Furthermore, when an alkaline solution and a surfactant are used together, their interaction enables more accurate removal.

[0062] The above describes exemplary embodiments of the present invention. That is, the detailed description and the accompanying drawings are disclosed for the purpose of illustrative explanation. Therefore, some of the components described in the detailed description and the accompanying drawings may be non-essential components for solving the problems. Therefore, just because these non-essential components are described in the detailed description and the accompanying drawings, it should not be immediately recognized that these non-essential components are essential.

[0063] Furthermore, the above-described embodiments are merely illustrative of the present invention in all respects. Various improvements and modifications to the above-described embodiments are possible within the scope of the present invention. For example, at least a portion of the configuration of any of the embodiments may be combined with at least a portion of the configuration of any of the other embodiments. In other words, when implementing the present invention, specific configurations can be appropriately adopted depending on the embodiment. [Explanation of symbols]

[0064] 10 Printed layer removal device, 20 Resin raw material manufacturing device, 30 Film manufacturing device, 40 Printed film, 42 Resin layer, 44 Printed layer, 50 Recycled film, 51, 53 Adjacent layer, 52 Intermediate layer, 100 Irradiation device, 110 Spraying device, 120 Polishing device, 130 Cleaning device, 140 Drying device, 400 Product section, 410 Edge section, P1 First area, P2 Second area, S1 Resource circulation system.

Claims

1. A method for removing a functional layer from a film including the functional layer, comprising: conveying the film from a payout roll to a take-up roll; A step of processing the film by irradiating the functional layer included in the film with high-energy rays while the film is being transported; removing the functional layer from the processed film by using an alkaline solution; the film includes a first region where the functional layer is laminated and a second region where the functional layer is not laminated, In the processing step, it is determined whether or not the functional layer is laminated at a position on the film to be irradiated with the high-energy beam, and the high-energy beam is irradiated onto the first region while not irradiated onto the second region; The removal method, wherein the alkaline solution has a pH of 8 or more and 11 or less.

2. The removal method according to claim 1 , wherein the step of removing the functional layer includes the step of removing the functional layer by subjecting the functional layer to a physical treatment.

3. The method of claim 1 or 2, wherein the step of removing the functional layer includes the step of cleaning the film.

4. A step of manufacturing a film from which the functional layer has been removed by using the removal method according to claim 1 or 2; and producing a recycled film by using the film from which the functional layer has been removed.

Images