Removal method, recycled film manufacturing method, and removal device

Abstract

A removal method according to the present invention is for removing a printed layer from a film including the printed layer. This removal method includes a conveying step for conveying a film from a feeding roll to a take-up roll, a heating step for heating the film so that the film thermally shrinks, and a physical processing step for physically processing the heat-shrunk film, in a conveying path, so that a printed layer is removed from the heat-shrunk film.

Description

Removal method, recycled film manufacturing method, and removal device

[0001] The present invention relates to a removal method, a method for manufacturing a recycled film, and a removal device.

[0002] Japanese Patent No. 6849141 (Patent Document 1) discloses a method for producing a heat-shrinkable film. The heat-shrinkable film is produced using a resin composition containing at least one of fluff and re-pellets obtained from a 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).

[0003] Patent No. 6849141

[0004] Many film products have patterns printed on them and contain colorants. Therefore, much of the waste film also contains colorants. When recycled film is produced using waste film, the colorants contained in the waste film affect the color of the recycled film. In order to reduce the effect of the colorants contained in the waste film on the color of the recycled film, it is possible to physically remove the printed layer from the waste film in advance. However, it is not necessarily easy to efficiently physically remove the printed layer. 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, a method for manufacturing recycled film, and a removal device that can efficiently physically remove a printed layer from a film that includes a printed layer.

[0006] A removal method according to one aspect of the present invention is a method for removing a printed layer from a film containing a printed layer, the removal method including a conveying step of conveying the film from a payout roll toward a take-up roll, a heating step of heating the film so that the film thermally shrinks, and a physical treatment step of physically treating the heat-shrunk film along the conveying path so that the printed layer is removed from the heat-shrunk film.

[0007] In this removal method, the film is heated and thermally shrunk before the printing layer is removed. Therefore, this removal method thickens the film before the printing layer is removed, preventing the film from breaking during removal of the printing layer, even if tension is applied to the film during transport. As a result, this removal method allows the printing layer to be removed while the film is being transported, thereby efficiently physically removing the printing layer from the film. Furthermore, this removal method reduces the film's width due to thermal shrinkage, preventing the size of the mechanisms required to perform each step from increasing.

[0008] In this removal method, the physical treatment step may include a first step of subjecting the film after heat shrinkage to physical treatment, and a second step of subjecting the film after the physical treatment in the first step to further physical treatment.

[0009] According to this removal method, the film is subjected to physical processing in two stages, so that the printed layer can be removed with higher precision.

[0010] In this removal method, in the second step, the film after the physical treatment in the first step may be subjected to a wet blasting treatment.

[0011] According to this removal method, the film is subjected to wet blasting in the second step, so that the removal debris remaining on the film surface in the first step can also be washed away from the film surface through the wet blasting.

[0012] In this removal method, in the physical treatment step, physical treatment may be applied to both surfaces of the heat-shrunk film.

[0013] In some films, a printed layer is laminated on one side of a resin layer and an overcoat layer (another printed layer) is laminated on the other side of the resin layer. According to this removal method, physical treatment is performed on both sides of the film after heat shrinkage, so that, for example, both the printed layer and the overcoat layer can be removed from the film.

[0014] In this removal method, the physical treatment step may involve subjecting the heat-shrunk film to blasting.

[0015] In this removal method, the physical treatment step may involve subjecting the heat-shrunk film to abrasion or grinding.

[0016] In the first step of this removal method, the heat-shrunk film may be subjected to a polishing or grinding treatment.

[0017] A method for producing a recycled film according to another aspect of the present invention produces a recycled film by using a film including a printed layer as a raw material. This method includes a transport step of transporting the film from a payout roll to a take-up roll, a heating step of heating the film so that the film thermally shrinks, a physical treatment step of physically treating the heat-shrunk film along the transport path so that the printed layer is removed from the heat-shrunk film, and a production step of producing a recycled film using the physically treated film.

[0018] In this method for producing recycled film, the film is heated and thermally shrunk before the printing layer is removed. Therefore, this method for producing recycled film thickens the film before the printing layer is removed, preventing the film from breaking during the removal of the printing layer, even if tension is applied to the film during transport. As a result, this method for producing recycled film removes the printing layer from the film through a physical process, reducing the generation of waste liquid compared to when the printing layer is removed solely through chemical processes. Furthermore, this method for producing recycled film reduces the film's width due to thermal shrinkage, preventing the increase in the size of the mechanisms required to perform each process.

[0019] A removal device according to another aspect of the present invention removes a printed layer from a film containing a printed layer. The removal device includes a conveying mechanism, a heating mechanism, and a physical processing mechanism. The conveying mechanism conveys the film from the payout roll toward the take-up roll. The heating mechanism heats the film so that the film undergoes thermal shrinkage. The physical processing mechanism applies physical processing to the heat-shrunk film along the conveying path so that the printed layer is removed from the heat-shrunk film.

[0020] In this removal device, the film is heated and thermally shrunk before the printing layer is removed. Therefore, with this removal device, the film becomes thicker before the printing layer is removed, which prevents the film from breaking during removal of the printing layer, even if tension is applied to the film during transport. As a result, with this removal device, the printing layer can be removed while the film is being transported, allowing for efficient physical removal of the printing layer from the film. Furthermore, with this removal device, the film's width is shortened due to thermal shrinkage, which prevents the size of the mechanisms required to perform each process from increasing.

[0021] According to the present invention, it is possible to provide a removal method, a method for producing recycled film, and a removal device that can efficiently physically remove a printed layer from a film that includes a printed layer.

[0022] FIG. 3 is a diagram schematically illustrating a resource circulation system. FIG. 4 is a plan view schematically illustrating an example of a printed film. FIG. 5 is a diagram schematically illustrating a cross section taken along line III-III in FIG. 2. FIG. 6 is a perspective view schematically illustrating the configuration of a printed layer removal device. FIG. 7 is a perspective view schematically illustrating the configuration of a heating mechanism. FIG. 8 is a perspective view schematically illustrating the configuration of a first removal mechanism. FIG. 9 is a perspective view schematically illustrating the configuration of a second removal mechanism 120. FIG. 10 is a flowchart showing an example of a manufacturing procedure for recycled film. FIG. 11 is a diagram schematically illustrating a cross section of an example of a recycled film to be manufactured. FIG. 12 is a perspective view schematically illustrating the configuration of a first removal mechanism in which a blade is provided instead of a metal file.

[0023] 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 identical 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 in a schematic manner with objects appropriately omitted or exaggerated.

[0024] [1. Overview] In recent years, marine pollution caused by plastic waste has become a global problem. Resource recycling has attracted attention as a means to address this problem.

[0025] FIG. 1 is a schematic diagram illustrating 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 a "printed film") is recycled to produce a 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 products, cosmetics, toiletries, or industrial / agricultural products. The following describes the recycling of waste heat-shrinkable film, a typical type of printed film.

[0026] 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 is appropriately selected taking into account the ease of attachment to a container or the like when used as a label. For example, when immersed in 90°C hot water 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 located 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. The printing on the film is performed by using, for example, a gravure printing plate.

[0027] The product part 400 is used for packaging plastic containers, glass containers, paper containers, etc. Each of the ear parts 410A, 410B has printed thereon information, etc., for checking the printing condition of the product part 400. The ear parts 410 are cut and wound up before the product part 400 is shipped. In this way, a roll of the product part 400 and the ear parts 410 is formed.

[0028] 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 design-formed side facing inward, then covering the container with the tubular label and heat-shrinking the tubular label to adhere it to the outer periphery of the body of the container. The tubular label is manufactured, for example, by the following method: A long, printed film is slit to the width of the design, an adhesive or solvent is applied to one end of the printed film, and the other end is overlapped and bonded together (center-sealed) to obtain a long, tubular label. The long, tubular label is then cut to obtain a single tubular label, which is then attached to the container.

[0029] FIG. 3 is a schematic diagram showing the cross section taken along 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, for example, a coloring component (colorant) such as ink that forms a pattern. In this example, the object to be packaged is placed on the printing layer 44 side. That is, when packaging is performed using the printed film 40, the printing layer 44 is located on the inside. The printing layer 44 may be a single layer or multiple layers. The thickness of the printing layer 44 is appropriately selected depending on the application, etc., but 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 or another printing 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, for the purpose of reducing scratches on the outer surface of the label. The innercoat layer and the overcoat layer are each formed, for example, during a pattern printing process. Each of the innercoat layer and the overcoat layer is included in the "printed layer" of the present invention.

[0030] 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. A thickness of the resin layer 42 within the above range provides excellent heat shrinkability, excellent converting properties such as printing and center sealing, and excellent wearability. Each layer constituting the resin layer 42 may also contain components other than resin. Each layer may contain metal components such as aluminum, inorganic components such as silicon oxide or aluminum oxide, 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.

[0031] 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 may be used. Examples of α-olefins include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The copolymer may be a random copolymer or a block copolymer. 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 of (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 styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, and acrylonitrile-styrene copolymers. Examples of polyamide-based resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the aliphatic polyamide include aliphatic nylon and copolymers thereof, specifically, 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), polydecamethyleneadipamide (nylon-10,8), etc. 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 thereof 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 of the diol 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.

[0032] 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 first open the tubular label into a film shape by peeling off the center seal, etc., in order 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 a printed film 40. The printed layer removal device 10 will be described in detail later.

[0033] 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 by 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.

[0034] FIG. 4 is a perspective view schematically illustrating the configuration of the printed layer removal device 10. Referring to FIG. 4 , in the printed layer removal device 10, a printed film 40 is transported from a payout roll (not shown) toward a take-up roll. The printed layer removal device 10 includes a heating mechanism 100, a first removing mechanism 110, a second removing mechanism 120, and a third removing mechanism 130. In the printed layer removal device 10, the heating mechanism 100, the first removing mechanism 110, the second removing mechanism 120, and the third removing mechanism 130 are arranged in this order from upstream to downstream along the transport path of the printed film 40. The heating mechanism 100 is configured to heat the printed film 40, and the first removing mechanism 110, the second removing mechanism 120, and the third removing mechanism 130 are each configured to perform a physical process on the printed film 40.

[0035] FIG. 5 is a perspective view schematically illustrating the configuration of the heating mechanism 100. Referring to FIG. 5, the heating mechanism 100 includes a heating roll 102 and a backup roll 104. The heating roll 102 is configured to heat the printed film 40 so that the printed film 40 thermally shrinks. The backup roll 104 is configured to press the thermally shrunk printed film 40 against the heating roll 102. The printed film 40, which is unwound from a feed roll (not shown), begins to thermally shrink upon contact with the heating roll 102. This shortens the width of the printed film 40, causing wrinkles to form in the printed film 40. The thermally shrunk printed film 40 is then sandwiched between the heating roll 102 and the backup roll 104, thereby smoothing out any wrinkles in the printed film 40 and allowing the printed film 40 to become substantially flat at the same time as the thermal shrinkage. The processing conditions set in the heating mechanism 100 are adjusted as appropriate depending on the material and thickness of the film so that the printed film 40 undergoes a predetermined thermal shrinkage. For example, the temperature of the heating roll 102 is preferably 60°C to 150°C, more preferably 70°C to 120°C, and the rotation speed (unwinding speed) is preferably approximately 3 m / min to 500 m / min.

[0036] For example, the processing conditions in the heating mechanism 100 are preferably set so that the thickness of the printed film 40 after heating is 1.7 to 7 times, preferably 1.6 to 5 times, and more preferably 2 to 4 times, the thickness of the printed film 40 before heating. Furthermore, the processing conditions in the heating mechanism 100 are preferably set so that the maximum difference in thickness in the width direction of the printed film 40 after heating is smaller than the thickness of the printed film 40 after heating (after thermal shrinkage), preferably less than two-thirds, more preferably less than one-half, and even more preferably less than one-third of the thickness. These processing conditions include, for example, the temperature and rotation speed of the heating roll 102, and the pressure applied to the printed film 40 by the heating roll 102 and backup roll 104. Note that the "thickness of the printed film 40 after heating" here refers to the average thickness of the central 80% of the width direction of the heated printed film 40, excluding the 10% from each end. By suppressing the maximum difference in thickness in the width direction of the printed film 40 after heating, it becomes easier for the metal file 114, etc. described below, to come into uniform contact with the surface of the printed film 40, making it less likely that the printed film 40 will break due to excessive contact of the metal file 114, etc. with the printed film 40.

[0037] The heating mechanism 100 is not limited to the method of sandwiching the printed film 40 between heated rolls, as long as the heating method causes the printed film 40 to undergo a predetermined thermal shrinkage. For example, methods such as immersion in hot water, passing through a hot air tunnel, or exposure to superheated steam can be appropriately selected. In the case of a printed film 40 whose primary shrinkage direction is in the film's longitudinal direction, the heating mechanism 100 may heat shrink the film without applying tension (relaxed). After the printed film 40 has been thermally shrunk, a separate mechanism may be provided to suppress any curl or wrinkles that may have occurred in the film to achieve a substantially flat state. While it is preferable for the heating mechanism 100 and the first removal mechanism 110, etc., to be processed on a continuous transport path, this is not a limitation. For example, the printed film 40 may be heat shrunk in an independent heating mechanism 100, and then processed in the first removal mechanism 110, etc.

[0038] In the printed layer removal device 10, the printed film 40 is heated before the printed layer 44 and other layers are removed from the printed film 40, causing the printed film 40 to thermally shrink. Therefore, with the printed layer removal device 10, the printed film 40 thickens before the printed layer 44 and other layers are removed. Therefore, even if tension is applied to the printed film 40 during transport, the printed film 40 is prevented from breaking as the printed layer 44 and other layers are removed. As a result, the printed layer removal device 10 can continuously remove the printed layer 44 and other layers while transporting a long length of printed film 40, thereby efficiently physically removing the printed layer 44 and other layers from the printed film 40. Furthermore, with the printed layer removal device 10, the printed film 40 shortens in the width direction due to thermal shrinkage of the printed film 40, preventing the first removal mechanism 110, the second removal mechanism 120, and the third removal mechanism 130 from becoming larger. As a result, with the printed layer removal device 10, for example, the widthwise size of the printed layer removal device 10 is reduced, so even if there are strict restrictions on the size of the installation location, it becomes possible to arrange multiple printed layer removal devices 10 side by side in the widthwise direction, and to perform parallel removal of printed layers 44, etc. on multiple printed films 40. In view of the above effects, the thermal shrinkage rate (main shrinkage direction) of the printed film 40 in the heating mechanism 100 is preferably, for example, 30% to 85%, more preferably 40% to 80%, and even more preferably 50% to 75%.

[0039] FIG. 6 is a perspective view schematically illustrating the configuration of the first removal mechanism 110. Referring to FIG. 6, the first removal mechanism 110 includes a plurality of (e.g., six) transport rolls 112 and a plurality of (e.g., three) metal files 114. The transport rolls 112 and the metal files 114 are alternately arranged from upstream to downstream along the transport path of the printed film 40. Each of the transport rolls 112 is configured to transport the printed film 40 from upstream to downstream. Each of the metal files 114 contacts the printed layer 44 of the transported printed film 40. Each of the metal files 114 is configured to roughen or remove the printed layer 44 of the printed film 40. The printed film 40 is transported with the metal files 114 in contact with the printed layer 44 of the printed film 40, thereby roughening or removing the printed layer 44 of the printed film 40. Each of the multiple metal files 114 may rotate, for example, while in contact with the printed layer 44 of the printed film 40. Removed debris of the printed layer 44 generated during this process is sucked up, for example, by a suction mechanism (not shown), collected, and discarded.

[0040] FIG. 7 is a perspective view schematically illustrating the configuration of the second removal mechanism 120. Referring to FIG. 7 , the second removal mechanism 120 includes a plurality of (e.g., 10) transport rolls 122, a plurality of (e.g., 3) polishing rolls 124, and a polishing roll 126. The polishing rolls 124, 126 and the transport rolls 122 are alternately arranged from upstream to downstream along the transport path of the printed film 40. Each of the transport rolls 122 is configured to transport the printed film 40 from upstream to downstream. Each of the polishing rolls 124 and the polishing roll 126 is made of, for example, ceramics. Each of the polishing rolls 124 is configured to roughen or remove the printed layer 44 of the printed film 40 while rotating in contact with the printed layer 44. The polishing roll 126 is configured to roughen or remove the overcoat layer of the printed film 40 while rotating in contact with the overcoat layer of the printed film 40. The removed debris of the printing layer 44 generated in this process is sucked up by, for example, a suction mechanism (not shown), collected, and discarded.

[0041] Referring again to FIG. 4 , the third removal mechanism 130 is configured to transport the printed film 40 from upstream to downstream and perform a wet blasting treatment on both sides of the printed film 40. In the third removal mechanism 130, media (abrasive material) and liquid (e.g., water) are sprayed onto both sides of the printed film 40. Note that the treatment performed by the third removal mechanism 130 on the printed film 40 does not necessarily have to be wet blasting, but may be simple blasting. If blasting is performed, the film may be cleaned after the treatment. The blasting treatment also makes it possible to remove scraped residue of the printed layer 44 from wrinkles and other recessed areas of the printed film 40 that cannot be reached by an abrasive roll or the like. The removed debris of the printed layer 44 generated during the blasting treatment is sucked up together with the media and liquid by, for example, a suction mechanism (not shown), and the removed debris is separated and discarded by a cyclone particle separator (not shown), while the media and liquid are reused in the blasting treatment.

[0042] In this way, the printed layer removal apparatus 10 applies physical processing to the printed film 40 in multiple stages. By first using the first removal mechanism 110, then the second removal mechanism 120, and then the third removal mechanism 130, the coarseness of the physical removal is gradually increased, allowing for the removal of most of the printed layer 44 in the first stage and the subsequent removal of the printed layer 44, including any remaining printed layer 44 in recesses in the film, with high precision. Therefore, the printed layer removal apparatus 10 can more accurately remove the printed layer 44 and other layers from the printed film 40. The conveyance speed of the printed layer removal apparatus 10 is adjusted as appropriate based on the capabilities of the heating mechanism 100 and each removal mechanism, but is preferably approximately 3 m / min to 500 m / min. Finally, the printed film 40 is subjected to a wet blasting process. Therefore, the printed layer removal apparatus 10 can also wash away any debris remaining on the surface of the printed film 40 in the previous process through the wet blasting process. Furthermore, the second removal mechanism 120 applies physical processing to both sides of the thermally shrunk printed film 40. Therefore, with the printed layer removal device 10, for example, when 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. However, while it is difficult to remove the overcoat layer by chemical removal such as immersion in an alkaline solution, this method makes it possible to remove the overcoat layer together with the printed layer 44, thereby reducing this effect.

[0043] 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. 8 is a flowchart showing an example of a recycled film manufacturing procedure. 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] Referring to Figure 8, the collected waste film is subjected to a printing layer removal process (physical deinking process) (step S100). In step S100, the printing layer is removed by mechanical action, such as rubbing, scraping, or peeling. In step S100, for example, at least physical removal may be used, and both chemical and physical removal may be used. In step S100, for example, the printing layer 44 and the like are removed from the printed film 40 using the printing layer removal device 10. By performing the printing layer removal process in step S100 and producing recycled raw materials from the waste film after the printing layer removal process, more recycled raw materials can be used in the production of recycled film.

[0046] 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 to process 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. By granulating in step S110, the bulk specific gravity of the waste film increases, thereby reducing the space required for storing the waste film.

[0047] 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.

[0048] 3. Example of Recycled Film FIG. 9 is a diagram schematically illustrating a cross section of an example of a manufactured recycled film. As shown in FIG. 9, the recycled film 50 includes an intermediate layer 52 and adjacent layers 51 and 53. In the recycled film 50, the intermediate layer 52 is sandwiched between the adjacent layers 51 and 53. In the recycled film 50, the intermediate layer 52 is made of a resin material containing virgin materials and recycled materials. Each of the adjacent layers 51 and 53 is made of virgin materials. Each of the adjacent layers 51 and 53 does not contain recycled materials. An adhesive layer may be provided between the intermediate layer 52 and the adjacent layers 51 and 53.

[0049] 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, polypropylene-based resins may be mixtures 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 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The copolymer may be a random copolymer or a block copolymer. 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 of (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 styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, and acrylonitrile-styrene copolymers. Examples of polyamide-based resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the aliphatic polyamide include aliphatic nylon and copolymers thereof, specifically, 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), polydecamethyleneadipamide (nylon-10,8), etc. 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 thereof 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 of the diol 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.

[0050] [4. Features] As described above, in the printing layer removal method according to the present embodiment, the printed film 40 is heated before the printing layer 44, etc. is removed, causing the printed film 40 to thermally shrink. Therefore, according to this removal method, the printed film 40 becomes thicker before the printing layer 44, etc. is removed. Therefore, even if tension is applied to the printed film 40 during transport, the printed film 40 is prevented from breaking as the printing layer 44, etc. is removed. As a result, according to this removal method, the printing layer 44, etc. can be removed while the printed film 40 is being transported, thereby efficiently physically removing the printing layer 44, etc. from the printed film 40. Furthermore, according to this removal method, the thermal shrinkage of the printed film 40 shortens the length of the printed film 40 in the width direction, preventing the size of the mechanisms implementing each process from increasing.

[0051] Furthermore, in the recycled film manufacturing method according to the present embodiment, the printed film 40 is heated before the removal of the printed layer 44, etc., causing the printed film 40 to thermally shrink. Therefore, according to this recycled film manufacturing method, the printed film 40 becomes thicker before the removal of the printed layer 44, etc., and therefore, even if the printed film 40 is under tension during transportation, the printed film 40 is prevented from breaking as the printed layer 44, etc. is removed. As a result, according to this recycled film manufacturing method, the removal of the printed layer 44, etc. from the printed film 40 is achieved by physical processing, which reduces the generation of waste liquid compared to when the removal of the printed layer 44, etc. from the printed film 40 is achieved solely by chemical processing. Furthermore, according to this recycled film manufacturing method, the length of the printed film 40 in the width direction is shortened by the thermal shrinkage of the printed film 40, thereby preventing the size of the mechanisms performing each process from increasing.

[0052] 5. Other Embodiments The concept of the above-described embodiment is not limited to the embodiment described above. Hereinafter, examples of other embodiments to which the concept of the above-described embodiment can be applied will be described.

[0053] <5-1> In the above embodiment, the first removal mechanism 110 includes a plurality of metal files 114. However, the configuration for performing physical processing on the printed layer 44 of the printed film 40 in the first removal mechanism 110 is not limited to this. For example, the first removal mechanism 110 may be provided with a blade with a sharp tip like a cutting edge instead of the metal files 114. Furthermore, the blade need not be fixed, but may be a rotating blade like an electric planer. Furthermore, a grinding stone may be provided instead of the metal files 114.

[0054] FIG. 10 is a perspective view schematically illustrating the configuration of a first removal mechanism 110A in which a blade 116 is provided instead of the metal file 114. Referring to FIG. 10 , the first removal mechanism 110A includes a plurality of (e.g., six) transport rolls 112 and a plurality of (e.g., three) blades 116. Each of the blades 116 has a sharp tip like a cutting edge, and the tip may be provided with a burr or fine irregularities to improve grinding properties. The tip of each of the blades 116 contacts the printed layer 44 of the printed film 40. As the printed film 40 is transported with the printed layer 44 in contact with the tip of the blade 116, the printed layer 44 is roughened or removed.

[0055] <5-2> In the above embodiment, the printing layer removal device 10 includes the first removal mechanism 110, the second removal mechanism 120, and the third removal mechanism 130. However, the printing layer removal device 10 does not necessarily include all of the first removal mechanism 110, the second removal mechanism 120, and the third removal mechanism 130. It is sufficient for the printing layer removal device 10 to include at least one mechanism that performs physical processing on the printed film 40. On the other hand, additional processes may be added to achieve more precise removal. As long as a heating mechanism that performs a heating process is provided upstream of the removal mechanism that performs the removal process, another removal mechanism that removes the printing layer 44 may be provided upstream of the heating mechanism. The type of mechanism that performs the physical processing is not limited as long as it can perform the desired removal process. Known devices other than the files, abrasive rolls, and blasters described in the above embodiment, such as metal rotating brushes, rotary blades, scrapers, belt sanders, etc., can be used alone or in combination. For example, a spiral blade (such as an end mill) or a comb-shaped blade may be used as the rotary blade. If a rotary blade that does not simultaneously contact the entire width of the printed film 40 is used, damage to the printed film 40 is reduced, making it less likely that the printed film 40 will break. Furthermore, by rotating the rotary blade in the forward direction relative to the feed direction of the printed film 40, it is possible to make it less likely that the printed film 40 will break. For example, the printed layer removal device 10 may include a first removal mechanism 110 and a second removal mechanism 120, in which a rotary blade is used as the first removal mechanism 110 and an abrasive roll is used as the second removal mechanism 120.

[0056] <5-3> In the above embodiment, the second removing mechanism 120 and the third removing mechanism 130 each performed physical processing on both sides of the printed film 40. However, the second removing mechanism 120 and the third removing mechanism 130 do not necessarily perform physical processing on both sides of the printed film 40. For example, the physical processing may be performed only on the side of the printed film 40 on which the printing layer 44 is formed.

[0057] <5-4> In addition, in the above embodiment, the first removing mechanism 110 performs physical processing on the printed film 40 immediately after it has been heated by the heating mechanism 100. However, the physical processing by the first removing mechanism 110 does not necessarily have to be performed on the printed film 40 immediately after it has been heated by the heating mechanism 100. For example, a cooling mechanism that cools the printed film 40 may be provided between the heating mechanism 100 and the first removing mechanism 110, and the physical processing by the first removing mechanism 110 may be performed on the printed film 40 that has been rapidly cooled by the cooling mechanism. An example of a cooling mechanism is a cooling roll, and the printed film 40 heated by the heating mechanism 100 may be rapidly cooled by being embraced by the cooling roll. Rapid cooling of the printed film 40 heated by the heating mechanism 100 suppresses crystallization of the resin that makes up the printed film 40, and as a result, the occurrence of breakage of the printed film 40 is suppressed. It is preferable that the printed film 40 be cooled in a short time (e.g., 10 seconds or less) by the cooling mechanism to a temperature below the crystallization temperature or the Vicat softening point of the resin that constitutes the printed film 40 (e.g., 20 to 50°C is preferred, and 20 to 30°C is more preferred).

[0058] <5-5> Furthermore, in the above embodiment, before the physical treatment is performed, the printed film 40 may be subjected to a treatment to facilitate removal of the printed layer 44. Examples of treatments to facilitate removal of the printed layer 44 include a treatment in which the printed film 40 is brought into contact with or immersed in a basic solvent, a surfactant, water, or other liquid that promotes peeling of the printed layer 44, and a treatment in which the printed film 40 is irradiated with energy rays such as ultraviolet light.

[0059] 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.

[0060] 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.

[0061] 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 Heating mechanism, 102 Heating roll, 104 Backup roll, 110, 110A First removal mechanism, 112, 122 Transport roll, 114 Metal file, 116 Blade, 120 Second removal mechanism, 124, 126 Polishing roll, 130 Third removal mechanism, 400 Product part, 410 Ear part, S1 Resource circulation system.

Claims

1. A method for removing a printed layer from a film containing the printed layer, comprising: a transport step of transporting the film from a payout roll to a take-up roll; a heating step of heating the film so that the film thermally shrinks; and a physical processing step of physically processing the film after thermal shrinkage along the transport path so that the printed layer is removed from the film after thermal shrinkage.

2. The removal method according to claim 1, wherein the physical treatment step includes a first step of subjecting the film after heat shrinkage to a physical treatment, and a second step of subjecting the film after the physical treatment in the first step to a further physical treatment.

3. The removal method according to claim 2, wherein in the second step, the film after the physical treatment in the first step is subjected to a wet blasting treatment.

4. A removal method according to any one of claims 1 to 3, wherein in the physical treatment step, physical treatment is applied to both sides of the film after heat shrinkage.

5. The removal method according to claim 1, wherein the physical treatment step includes subjecting the film to a blast treatment after heat shrinkage.

6. The removal method according to claim 1, wherein the physical treatment step involves subjecting the heat-shrunk film to a polishing or grinding treatment.

7. A removal method according to claim 2 or 3, wherein in the first step, the film after heat shrinkage is subjected to a polishing or grinding treatment.

8. A method for producing recycled film by using a film including a printed layer as a raw material, the method comprising: a transport step of transporting the film from a payout roll to a take-up roll; a heating step of heating the film so that the film undergoes thermal shrinkage; a physical processing step of physically processing the film after thermal shrinkage along the transport path so that the printed layer is removed from the film after thermal shrinkage; and a manufacturing step of producing the recycled film by using the film after the physical processing.

9. A removal device for removing a printed layer from a film containing the printed layer, comprising: a transport mechanism for transporting the film from a payout roll to a take-up roll; a heating mechanism for heating the film so that the film undergoes thermal shrinkage; and a physical processing mechanism for physically processing the film after thermal shrinkage along the transport path so that the printed layer is removed from the film after thermal shrinkage.

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