Removal method and method for manufacturing a recycled film

Abstract

Provided are a removal method capable of efficiently removing a functional layer from a film including the functional layer, and a method for manufacturing a recycled film using the removal method. 【Solution means】The removal method removes the functional layer from the film including the functional layer. The film is conveyed from upstream to downstream. A first heating mechanism and a second heating mechanism located downstream of the first heating mechanism are provided in the conveyance path of the film. The removal method includes a step of manufacturing a heat-shrunk film through heating of the film by the first heating mechanism and heating of the film by the second heating mechanism, and a step of removing the functional layer from the heat-shrunk film. The temperature of the first heating mechanism is lower than the temperature of the second heating mechanism.

Description

Technical Field

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

Background Art

[0002] Japanese Patent Application Laid-Open No. 2010-89434 (Patent Document 1) discloses a resin recycling apparatus. In this resin recycling apparatus, the resin is softened through heating, and the surface layer of the softened resin is flattened. Thereafter, the surface layer of the flattened resin is removed, and the resin with the surface layer removed is recycled (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Many film products are provided with functional layers such as printing layers. Therefore, many film waste materials also contain foreign substances such as colorants. When manufacturing a recycled film using film waste materials, the foreign substances contained in the film waste materials affect the quality of the recycled film. In order to suppress the influence of the foreign substances contained in the film waste materials on the quality of the recycled film, it is conceivable to remove the functional layer from the film waste materials in advance. However, it is not always easy to efficiently remove the functional layer. The above Patent Document 1 does not disclose a solution to such a problem.

[0005] The present invention has been made to solve such problems, and an object thereof is to provide a removal method capable of efficiently removing a functional layer from a film containing the functional layer, and a method for manufacturing a recycled film using the removal method.

Means for Solving the Problems

[0006] A removal method according to an aspect of the present invention removes a functional layer from a film including the functional layer. The film is conveyed from upstream to downstream. A first heating mechanism and a second heating mechanism located downstream of the first heating mechanism are provided in the conveyance path of the film. The removal method includes a step of manufacturing a heat-shrunk film through heating of the film by the first heating mechanism and heating of the film by the second heating mechanism, and a step of removing the functional layer from the heat-shrunk film. The temperature of the first heating mechanism is lower than the temperature of the second heating mechanism.

[0007] The present inventors have found that when a film including a functional layer is rapidly heated in a high-temperature state, a large number of wrinkles and the like are generated in the film due to heat shrinkage. When a large number of wrinkles and the like are generated in the film, it becomes difficult to efficiently remove the functional layer. In this removal method, the temperature of the first heating mechanism is lower than the temperature of the second heating mechanism located downstream of the first heating mechanism. Therefore, according to this removal method, since the film is suppressed from rapidly heat-shrinking in a high-temperature state, the generation of wrinkles and the like in the heat-shrunk film can be suppressed. As a result, according to this removal method, the removal of the functional layer in the heat-shrunk film can be performed more efficiently.

[0008] In this removal method, the heat-shrunk film may be stretched in the conveyance direction of the film.

[0009] According to this removal method, since the heat-shrunk film is stretched in the conveyance direction of the film, the generation of wrinkles and the like in the heat-shrunk film can be further suppressed.

[0010] In this removal method, the stretching ratio of the film in the conveyance direction of the film may be less than 2 times, and the thickness of the film may be 2 times or more after heating of the film by the first heating mechanism and heating of the film by the second heating mechanism.

[0011] In this removal method, through the heating of the film by the first heating mechanism and the heating of the film by the second heating mechanism, the thickness of the film becomes twice or more. Therefore, according to this removal method, for example, when the removal of the functional layer is physically performed, breakage of the film after heat shrinkage is less likely to occur, so that the removal of the functional layer in the film after heat shrinkage can be performed more efficiently.

[0012] In this removal method, the functional layer may include a printing layer, the film may include a printed portion where the printing layer is formed and a transparent portion where the printing layer is not formed, and in the film, the printed portion and the transparent portion may be alternately formed in the film conveyance direction.

[0013] Generally, the degree of heat shrinkage is different between the printed portion and the transparent portion. Therefore, for example, when a film including a printed portion and a transparent portion rapidly shrinks thermally, wrinkles are likely to occur. According to this removal method, since rapid thermal shrinkage of the film in a high-temperature state is suppressed, even when the printed portion and the transparent portion are alternately formed in the film, the occurrence of wrinkles and the like in the film after heat shrinkage can be suppressed.

[0014] In this removal method, in the step of removing the functional layer from the film after heat shrinkage, a physical treatment may be performed on the film after heat shrinkage in order to remove the functional layer from the film after heat shrinkage.

[0015] In this removal method, the shrinkage rate of the film at the temperature of the first heating mechanism may be less than 47%.

[0016] According to this removal method, since the shrinkage rate of the film at the temperature of the first heating mechanism is less than 47% and rapid thermal shrinkage of the film is suppressed, the occurrence of wrinkles and the like in the film after heat shrinkage can be suppressed.

[0017] In this removal method, there may be no other heating mechanism between the first heating mechanism and the second heating mechanism, and the difference between the shrinkage rate of the film at the temperature of the first heating mechanism and the shrinkage rate of the film at the temperature of the second heating mechanism may be less than 47%.

[0018] According to this removal method, the difference between the shrinkage rate of the film at the temperature of the first heating mechanism and the shrinkage rate of the film at the temperature of the second heating mechanism is less than 47%, and since the film is suppressed from rapidly thermally shrinking, the occurrence of wrinkles and the like in the film after thermal shrinkage can be suppressed.

[0019] The method for manufacturing a recycled film according to another aspect of the present invention includes a step of manufacturing a film in which a functional layer has been removed by using the above removal method, and a step of manufacturing a recycled film by using the film in which the functional layer has been removed.

[0020] In this method for manufacturing a recycled film, the removal of the functional layer in the film after thermal shrinkage is performed more efficiently. Therefore, according to this method for manufacturing a recycled film, a recycled film can be efficiently manufactured by using a film in which the functional layer has been efficiently removed.

Effects of the Invention

[0021] According to the present invention, it is possible to provide a removal method capable of efficiently removing a functional layer from a film including the functional layer, and a method for manufacturing a recycled film using the removal method.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments according to one aspect of the present invention (hereinafter, also referred to as "the present embodiment") will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. Also, each drawing is schematically drawn with appropriate omissions or exaggerations of the subject for easy understanding.

[0024] [1. Configuration of Resource Recycling System, etc.] FIG. 1 is a diagram schematically showing the configuration of a resource recycling system S1 using the method for manufacturing a recycled film according to the present embodiment. Referring to FIG. 1, in the resource recycling system S1, for example, a resin film printed with a pattern (hereinafter, also referred to as a "printed film") is recycled to produce a new film. The pattern is composed of, for example, a pattern, characters, symbols (for example, barcodes) or a combination thereof. The printed film is, for example, a packaging material such as a heat-shrinkable film or a label that can be used for food, beverages, pharmaceuticals, medical products, cosmetics, toiletries, or industrial and agricultural supplies. Hereinafter, the case of recycling waste materials of a heat-shrinkable film, which is a typical printed film, will be described.

[0025] FIG. 2 is a plan view schematically showing an example of a printed film. In this example, the printed film 40 is a heat-shrinkable film in a state before heat shrinkage having a printing layer. The printed film 40 is a long film having a longitudinal direction and a width direction. The longitudinal direction is the conveyance direction (MD (Machine Direction)) during the production of the film by Roll-to-Roll, and the width direction is the direction orthogonal to the conveyance direction (TD (Transvers Direction)).

[0026] The printed film 40 is managed in a wound body (roll) shape from the viewpoints of storage and handling. The printed film 40 may mainly shrink in the horizontal one-axis direction (width direction), for example, for use as a cylindrical label. The heat shrinkage rate (main shrinkage direction) of the resin layer 42 (see FIG. 3) is appropriately selected in consideration of the mountability to a container or the like when used as a label. For example, when immersed in hot water at 90° C. for 10 seconds, it is preferably 30% or more, and more preferably 50% or more.

[0027] As shown in FIG. 2, the printed film 40 includes a product portion 400 and ears 410A and 410B. The ears 410 are provided at positions adjacent to each of both ends of the product portion 400 in the width direction. A pattern is printed on each of the product portion 400 and the ears 410. Printing on the film is performed, for example, by using a gravure plate.

[0028] The product unit 400 is used for packaging such as plastic containers, glass containers, and paper containers. The product unit 400 includes a printing section P1 and a transparent section P2. In the product unit 400, in the MD, the printing section P1 and the transparent section P2 are alternately formed. A pattern is printed on the printing section P1, and no pattern is printed on the transparent section P2. The length of the transparent section P2 in the MD is, for example, 0.5 cm or more and 10 cm or less. In each of the ears 410A and 410B, information for checking the printing state in the product unit 400 and the like is printed. The ear 410 is cut and wound up before the product unit 400 is shipped. Thereby, a wound body of the product unit 400 and the ear 410 is formed.

[0029] The printed film (product unit 400) with a pattern printed thereon is attached as a label to the outer periphery of the body of the container. As a method of attaching to the container, for example, a method of winding the label around the container, and a method of forming a cylindrical label (hereinafter, also referred to as a "cylindrical label") by bonding both ends of the printed film with the surface on which the pattern is formed facing inward, and then heat-shrinking the cylindrical label after covering the container with the cylindrical label to closely attach the label to the outer periphery of the body of the container. The cylindrical label is manufactured, for example, by the following method. A long printed film is slit to the width for each pattern, a solvent or the like is applied to one end in the TD of the printed film, and the other end is overlapped and bonded (center-sealed) to obtain a long cylindrical label. One cylindrical label is obtained by cutting the long cylindrical label, and one cylindrical label is attached to the container.

[0030] FIG. 3 is a diagram schematically showing a 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 (coloring agent) such as ink for forming a pattern. In this example, the object to be packaged is disposed on the printing layer 44 side. That is, when packaging is performed using the printed film 40, the printing layer 44 is located inside. The printing layer 44 may be not only a single layer but also a multilayer. The thickness of the printing layer 44 can be appropriately selected according to the application or the like, but can be, for example, about 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 (on the side opposite to the printing layer 44). The inner coat layer is formed, for example, for the purpose of improving the slipperiness of the inner surface of the tubular label between the object to be packaged and the mounting device. The overcoat layer is formed, for example, for the purpose of reducing damage to the outer surface of the label. Each of the inner coat layer and the overcoat layer is formed, for example, in the printing process of the pattern. Each of the inner coat layer, the printing layer, and the overcoat layer is included in the "functional layer" in the present invention.

[0031] The resin layer 42 may be composed of a single layer or may be composed of a plurality of laminated layers. The resin layer 42 may include a layer in which different types of resins are mixed, or may include a plurality of layers each containing a different type of resin. The overall thickness of the resin layer 42 can be appropriately selected according to the application, but is preferably 10 μm or more and 60 μm or less, more preferably 12 μm or more and 50 μm or less, and even more preferably 15 μm or more and 40 μm or less. When the thickness of the resin layer 42 is within the above range, excellent heat shrinkability, printing, excellent convertibility such as center sealing, or excellent mountability can be obtained. Further, each layer constituting the resin layer 42 may contain components other than the resin. Each layer may contain a metal component such as aluminum, an anti-blocking agent, an additive, or the like. Examples of the additive include a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, an antistatic agent, a flame retardant, an antibacterial agent, and a fluorescent brightening agent.

[0032] Examples of the types of resins contained in each layer include polyolefin resins, polystyrene resins, polyamide resins, and polyester resins. Examples of polyolefin resins include polypropylene-based, polyethylene-based, and cyclic polyolefin-based resins. Examples of polypropylene-based resins include binary or ternary random copolymers having propylene as a main component and ethylene, butene, or α-olefin as a copolymerization component. Specifically, the α-olefin is preferably composed of ethylene, 1-butene, 1-hexene, 1-octene, etc., and may contain two or more types of α-olefins. Further, 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, or mixtures thereof. Also, copolymers of ethylene and α-olefin are included. Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. The copolymer may be a random copolymer or a block copolymer. Examples of cyclic olefin-based resins include, for example, (a) copolymers of ethylene or propylene and 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) above, (d) graft-modified products of (a) to (c) above with unsaturated carboxylic acids and their derivatives, etc. The cyclic olefin is not particularly limited, and specifically, for example, norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, 5-benzylnorbornene, etc. may be mentioned.Examples of polystyrene resins include homopolymers of styrene monomers and copolymers composed of styrene monomers and other monomers (such as conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Specifically, 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, rubber-modified impact-resistant polystyrene, etc. can be mentioned. More specifically, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), multi-branched polystyrene, etc. can be mentioned. Examples of polyamide resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the above aliphatic polyamides include aliphatic nylons and their copolymers. Specifically, polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecanamide (nylon-11), polylauryl lactam (nylon-12), polyethylene diamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), etc. can be mentioned. Examples of polyester resins include those obtained by condensation polymerization of a dicarboxylic acid component and a diol component. The type of the above dicarboxylic acid component is not particularly limited, and terephthalic acid, o-phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylene carboxylic acid, anhydrides and lower alkyl esters thereof, etc. can be exemplified.The type of the above-mentioned diol component is not particularly limited, and examples thereof include aliphatic diols such as 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-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, polytetramethylene ether glycol, etc.; alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.

[0033] Referring again to FIG. 1, the resource recycling system S1 includes a film heating device 5, a printing layer removing device 10, a resin raw material manufacturing device 20, and a film manufacturing device 30. The film heating device 5 is configured to heat-shrink a film waste material, for example, a used printed film or label, an ear portion cut from the printed film and collected in a roll shape, or a waste material of the printed film generated in the manufacturing process such as a proofing film (hereinafter also referred to as "film waste material"). The film heating device 5 will be described in detail later.

[0034] The printing layer removing device 10 is configured to remove the printing layer from, for example, waste film materials. When removing the printing layer from a cylindrical label, in order to efficiently remove the printing layer, it is desirable to unfold the cylindrical label into a film shape by peeling the center seal or the like in advance. Note that the history of the printed film 40 from which the printing layer is removed in the printing layer removing device 10 is not particularly limited, and may be, for example, unused products, intermediate processed products, remaining products, defective products, prototype products, waste products, etc. The printing layer removing device 10 removes, for example, the printing layer 44, the inner coat layer, and the overcoat layer (hereinafter also referred to as "the printing layer 44 etc.") from the printed film 40. The printing layer removing device 10 will be described in detail later.

[0035] The resin raw material manufacturing device 20 is configured to manufacture a resin raw material using the printed film 40 from which the printing layer 44 etc. has been removed in the printing layer removing device 10. The film manufacturing device 30 is configured to manufacture a film by using the resin raw material manufactured by the resin raw material manufacturing device 20.

[0036] FIG. 4 is a front view schematically showing a part of the configuration of the film heating device 5. Referring to FIG. 4, in the film heating device 5, the printed film 40 is conveyed from upstream to downstream. The film heating device 5 includes a plurality of heating rolls 50 and a plurality of backup rolls 51. Each of the plurality of heating rolls 50 is configured to heat the printed film 40 so that the printed film 40 thermally contracts. Each of the plurality of backup rolls 51 is configured to press the printed film 40 after thermal contraction against the corresponding heating roll 50. The printed film 40 fed out from an unillustrated pay-out roll thermally contracts by contacting each heating roll 50.

[0037] In the film heating device 5, a set including a heating roll 50A and a backup roll 51A, a set including a heating roll 50B and a backup roll 51B, a set including a heating roll 50C and a backup roll 51C, and a set including a heating roll 50D and a backup roll 51D are arranged in this order from upstream to downstream in the conveyance direction of the printed film 40.

[0038] In the film heating device 5, with respect to two adjacent heating rolls 50 in the conveyance direction, the temperature of the downstream heating roll 50 is equal to or higher than the temperature of the upstream heating roll 50. That is, in the film heating device 5, the heating temperature of the printed film 40 gradually increases. The temperature of the heating roll 50A at which the printed film 40 is first heated is preferably a temperature at which the heat shrinkage rate (hereinafter, also simply referred to as "shrinkage rate") when the printed film 40 is immersed in warm water at that temperature for 10 seconds is less than 47%, and more preferably a temperature at which the shrinkage rate is 34% or less. Also, with respect to two adjacent heating rolls 50 in the conveyance direction, the difference between the shrinkage rate of the printed film 40 at the temperature of the downstream heating roll 50 and the shrinkage rate of the printed film 40 at the temperature of the upstream heating roll 50 is preferably less than 47%, more preferably the difference between the shrinkage rate of the printed film 40 at the temperature of the downstream heating roll 50 and the shrinkage rate of the printed film 40 at the temperature of the upstream heating roll 50 is 38% or less, and even more preferably the difference between the shrinkage rate of the printed film 40 at the temperature of the downstream heating roll 50 and the shrinkage rate of the printed film 40 at the temperature of the upstream heating roll 50 is 29% or less.

[0039] The inventors have found that when the printed film 40 is rapidly heated in a high-temperature state, numerous wrinkles and the like are generated in the printed film 40 due to heat shrinkage. When the printed film 40 is rapidly heated in a high-temperature state, for example, numerous wrinkles extending in the MD and edge disturbances at both ends of the TD occur. Edge disturbance means that at the edge of the printed film 40, the shape of the printed film 40 is disturbed by folding or the like. When numerous wrinkles and the like are generated in the printed film 40, it becomes difficult to efficiently remove the printing layer 44 and the like. In the film heating device 5, the temperature of the upstream heating roll 50 is lower than the temperature of the downstream heating roll 50. Therefore, according to the film heating device 5, since the rapid heat shrinkage of the printed film 40 in a high-temperature state is suppressed, the generation of wrinkles and the like in the printed film 40 after heat shrinkage can be suppressed. As a result, according to the resource recycling system S1, the removal of the printing layer 44 and the like in the printed film 40 after heat shrinkage can be performed more efficiently.

[0040] Further, in the printed film 40, the printing portion P1 and the transparent portion P2 are alternately formed in the conveyance direction of the printed film 40. Generally, the degree of heat shrinkage is different between the printing portion P1 and the transparent portion P2. Therefore, for example, when a film including the printing portion P1 and the transparent portion P2 rapidly heat shrinks, wrinkles are likely to occur. According to the film heating device 5, since the rapid heat shrinkage of the printed film 40 in a high-temperature state is suppressed, even if the printing portion P1 and the transparent portion P2 are alternately formed in the printed film 40, the generation of wrinkles and the like in the printed film 40 after heat shrinkage can be suppressed.

[0041] In addition, in the film heating device 5, with respect to two adjacent heating rolls 50 in the conveying direction, the rotational speed of the downstream heating roll 50 is equal to or higher than the rotational speed of the upstream heating roll 50. As a result, in the film heating device 5, the printed film 40 is stretched in the conveying direction of the printed film 40. Note that the stretching ratio of the printed film 40 is preferably 1.0 times or more and less than 2 times, more preferably 1.1 times or more and 1.8 times or less, and even more preferably 1.2 times or more and 1.5 times or less. By stretching the printed film 40, the occurrence of wrinkles and the like in the printed film 40 is further suppressed.

[0042] The film heating device 5 is not limited to the method of sandwiching with the heating roll 50 as long as it is a heating method for causing a predetermined heat shrinkage in the printed film 40. For example, a method of immersing in hot water, a method of passing through a hot air tunnel, a method of applying superheated steam, etc. may be appropriately selected. A mechanism for suppressing film curl and wrinkles generated after heat-shrinking the printed film 40 to make it substantially flat may be provided separately. It is preferably arranged on a continuous conveying path for the film heating device 5 and the printing layer removing device 10, etc., but is not limited thereto. For example, after the printed film 40 is heat-shrunk by an independent film heating device 5, the printed film 40 may be processed by the printing layer removing device 10, etc. in another conveying path.

[0043] In the resource recycling system S1, before the printed film 40 is removed from the printed layer 44 and the like, the printed film 40 is heated and the printed film 40 thermally contracts. Therefore, according to the resource recycling system S1, since the printed film 40 becomes thicker before the removal of the printed layer 44 and the like, even if tension is applied to the printed film 40 for conveyance, it is possible to suppress the occurrence of a situation where the printed film 40 breaks as the printed layer 44 and the like are removed. As a result, according to the resource recycling system S1, since the printed layer 44 and the like can be continuously removed while conveying the long printed film 40, the removal of the printed layer 44 and the like from the printed film 40 can be efficiently performed. Further, according to the resource recycling system S1, since the length of the printed film 40 in the width direction becomes shorter due to the thermal contraction of the printed film 40, it is possible to suppress an increase in the size of the printed layer removing device 10. From the viewpoint of the above effects, the thermal contraction rate (main contraction direction) of the printed film 40 in the film heating device 5 is preferably, for example, 30% to 85%, more preferably 40% to 80%, and even more preferably 50% to 75%. Further, it is preferable that the thickness of the printed film 40 becomes twice or more through the heating in the film heating device 5, and it is even more preferable that the thickness becomes 2.5 times or more.

[0044] FIG. 5 is a diagram schematically showing the configuration of the printed layer removing device 10. In the printed layer removing device 10, the printed film 40 is conveyed from upstream to downstream. The printed layer removing device 10 includes a first removing mechanism 110, a second removing mechanism 120, and a third removing mechanism 130. In the printed layer removing device 10, 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 in the conveyance path of the printed film 40. Each of the first removing mechanism 110, the second removing mechanism 120, and the third removing mechanism 130 is configured to perform a physical process on the printed film 40 after thermal contraction.

[0045] FIG. 6 is a perspective view schematically showing the configuration of the first removing mechanism 110. Referring to FIG. 6, the first removing mechanism 110 includes a plurality (for example, six) of conveying rolls 112 and a plurality (for example, three) of emery papers 114. The plurality of conveying rolls 112 and the plurality of emery papers 114 are alternately arranged in sequence from the upstream to the downstream of the conveyance path of the printed film 40. Each of the plurality of conveying rolls 112 is configured to convey the printed film 40 from the upstream to the downstream. Each of the plurality of emery papers 114 is in contact with the printing layer 44 of the conveyed printed film 40. Each of the plurality of emery papers 114 is configured to roughen or remove the printing layer 44 of the printed film 40. By conveying the printed film 40 in a state where the emery paper 114 is in contact with the printing layer 44 of the printed film 40, the printing layer 44 of the printed film 40 is roughened or removed. Each of the plurality of emery papers 114 may rotate, for example, while being in contact with the printing layer 44 of the printed film 40. The removal debris of the printing layer 44 generated in this process is sucked, collected, and discarded by, for example, a suction mechanism (not shown).

[0046] FIG. 7 is a perspective view schematically showing the configuration of the second removing mechanism 120. Referring to FIG. 7, the second removing mechanism 120 includes a plurality (for example, ten) of conveying rolls 122, a plurality (for example, three) of polishing rolls 124, and a polishing roll 126. The plurality of polishing rolls 124, 126 and the plurality of conveying rolls 122 are alternately arranged in sequence from the upstream to the downstream of the conveyance path of the printed film 40. Each of the plurality of conveying rolls 122 is configured to convey the printed film 40 from the upstream to the downstream. Each of the plurality of polishing rolls 124 and the polishing roll 126 is made of, for example, ceramics. Each of the plurality of polishing rolls 124 is configured to roughen or remove the printing layer 44 of the printed film 40 while rotating in a state of being in contact with the printing layer 44 of the printed film 40. The polishing roll 126 is configured to roughen or remove the overcoat layer of the printed film 40 while rotating in a state of being in contact with the overcoat layer of the printed film 40. The removal debris of the printing layer 44 generated in this process is sucked, collected, and discarded by, for example, a suction mechanism (not shown).

[0047] Referring again to FIG. 5, the third removing mechanism 130 is configured to convey the printed film 40 from upstream to downstream and perform wet blasting treatment on both sides of the printed film 40. In the third removing mechanism 130, media (abrasive) and liquid (e.g., water) are sprayed onto both sides of the printed film 40. Note that the treatment performed by the third removing mechanism 130 on the printed film 40 does not necessarily have to be wet blasting treatment, and it may be merely blasting treatment. When performing blasting treatment, the film may be washed after the treatment. By performing blasting treatment, it is also possible to remove the remaining printed layer 44 in the recessed portions such as wrinkles of the printed film 40 that could not be reached by a polishing roll or the like. The removed chips of the printed layer 44 generated by the blasting treatment are, for example, sucked together with the media and liquid by a suction mechanism (not shown), the removed chips are separated by a cyclone classifier (not shown) and discarded, and the media and liquid are reused in the blasting treatment.

[0048] Thus, in the printing layer removing apparatus 10, physical processing is performed on the printed film 40 in multiple stages. By making the coarseness of the physical removal gradually finer in the order of the first removal mechanism 110, the second removal mechanism 120, and the third removal mechanism 130, with the coarsest at the beginning, most of the printing layer 44 can be removed in the previous stage, and high-precision removal can be performed in the subsequent stage, including the printing layer 44 remaining in the recesses of the film and the like. Therefore, according to the printing layer removing apparatus 10, the removal of the printing layer 44 and the like on the printed film 40 can be performed with higher precision. The conveyance speed of the printing layer removing apparatus 10 is appropriately adjusted according to the capabilities of each removal mechanism and the like, but for example, it is preferably about 3 m / min to 500 m / min. Also, in the printing layer removing apparatus 10, the printed film 40 is finally subjected to wet blasting treatment. Therefore, according to the printing layer removing apparatus 10, the removal debris remaining on the surface of the printed film 40 in the previous process can also be washed away from the film surface through the wet blasting treatment. Further, in the second removal mechanism 120, physical processing is performed on both sides of the printed film 40 after heat shrinkage. Therefore, according to the printing layer removing apparatus 10, for example, when an overcoat layer is formed on the printed film 40, both the printing 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 causes a decrease in the haze of the recycled film, etc., but in this method, since the overcoat layer can be removed together with the printing layer 44, the influence can be reduced.

[0049] Referring to FIG. 1 again, the recycled film produced by the film manufacturing apparatus 30 is printed again. That is, the printed film 40 is produced again. A part of the produced printed film 40 is put into the resource recycling system S1 again. By repeating this cycle, resource recycling is realized.

[0050] [2. Manufacturing Procedure of Recycled Film] FIG. 8 is a flowchart showing an example of a manufacturing procedure of a recycled film. Each step shown in this flowchart starts with the state where film waste materials are collected. The film waste materials can include various types of films with various types of printing applied thereto. Note that the film waste materials do not necessarily have to include various types of films with various types of printing applied thereto, and for example, only one type of film may be included. For example, only a predetermined type of film among the waste materials collected from a factory or the like may be recycled as the film waste materials.

[0051] Referring to FIG. 8, a heat treatment is performed on the collected film waste materials (step S100). In step S100, by gradually raising the heating temperature of the film waste materials, the occurrence of sudden heat shrinkage of the film waste materials is suppressed. After heating the film waste materials, a removal process of the printing layer (for example, a physical deinking process) is performed (step S110). In step S110, for example, the printing layer is removed by a mechanical action such as rubbing, scraping, or peeling. In step S110, for example, both chemical removal and physical removal may be used. In step S110, for example, by using the printing layer removing apparatus 10, the printing layer 44 and the like are removed from the printed film 40. By performing the removal process of the printing layer in step S110 and manufacturing a recycled raw material from the film waste materials after the removal process of the printing layer, more recycled raw materials can be used in the manufacture of the recycled film.

[0052] When the removal of the printing layer is completed in step S110, recycled raw materials are produced by granulating the film waste material after the removal of the printing layer (step S120). Step S120 is performed, for example, by the resin raw material manufacturing apparatus 20. The resin raw material manufacturing apparatus 20 is realized by, for example, various known apparatuses capable of granulating film waste materials. In step S120, the film waste material after the removal of the printing layer is processed into a granular form. Examples of the granulation method include melt granulation and compression granulation. In melt granulation, the melt-kneaded film waste material is extruded, and the extruded film waste material is water-cooled and cut at the die outlet, whereby the film waste material is processed into a granular form. In compression granulation, the film waste material is processed into a granular form by compression molding. In step S120, additives (for example, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, fluorescent brighteners, virgin raw materials, antiblocking agents) may be added to the film waste material. By performing granulation in step S120, the bulk specific gravity of the film waste material increases, and the space required for storing the film waste material decreases.

[0053] When recycled raw materials are produced in step S120, a film forming process of the recycled film is performed by the film manufacturing apparatus 30 (step S130). Note that the resin raw material used for manufacturing the recycled film may contain, among others, biomass-derived raw materials or chemical recycling raw materials.

[0054] [3. An Example of the Recycled Film] FIG. 9 is a diagram schematically showing a cross section of an example of the recycled film to be manufactured. As shown in FIG. 9, the recycled film 60 includes an intermediate layer 62 and adjacent layers 61 and 63. In the recycled film 60, the intermediate layer 62 is sandwiched between the adjacent layers 61 and 63. In the recycled film 60, the intermediate layer 62 is composed of a resin material containing virgin raw material and recycled raw material. Each of the adjacent layers 61 and 63 is composed of virgin raw material. Each of the adjacent layers 61 and 63 does not contain recycled raw material. Note that an adhesive layer may be provided between the intermediate layer 62 and the adjacent layers 61 and 63.

[0055] Examples of the types of resins that make up the virgin raw materials contained in each layer include polyolefin resins, polystyrene resins, polyamide resins, and polyester resins. Examples of polyolefin resins include polypropylene-based, polyethylene-based, and cyclic polyolefin resins. Examples of polypropylene-based resins include binary or ternary random copolymers having propylene as a main component and ethylene, butene, or α-olefin as a copolymerization component. Specifically, the α-olefin is preferably composed of ethylene, 1-butene, 1-hexene, 1-octene, etc., and may contain two or more types of α-olefins. Also, 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, or mixtures thereof. Also included are copolymers of ethylene and α-olefins. Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. The above copolymers may be random copolymers or block copolymers. Examples of cyclic olefin-based resins include, for example, (a) copolymers of ethylene or propylene and 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) above, (d) graft-modified products of (a) to (c) above with unsaturated carboxylic acids and their derivatives, etc. The above cyclic olefins are not particularly limited, and specifically, for example, norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, 5-benzylnorbornene, etc. can be mentioned.Examples of polystyrene resins include homopolymers of styrene monomers and copolymers composed of styrene monomers and other monomers (such as conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Specifically, 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, rubber-modified impact-resistant polystyrene, etc. can be mentioned. More specifically, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), multi-branched polystyrene, etc. can be mentioned. Examples of polyamide resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the above-mentioned aliphatic polyamides include aliphatic nylons and their copolymers. Specifically, polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecanamide (nylon-11), polylauryl lactam (nylon-12), polyethylene diamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), etc. can be mentioned. Examples of polyester resins include those obtained by polycondensing a dicarboxylic acid component and a diol component. The type of the above-mentioned dicarboxylic acid component is not particularly limited, and terephthalic acid, o-phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylene carboxylic acid, their anhydrides and lower alkyl esters, etc. can be exemplified.The type of the above diol component is not particularly limited, and examples thereof include aliphatic diols such as 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-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, polytetramethylene ether glycol, etc.; alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.

[0056] [4. Features] As described above, in the resource circulation system S1, the temperature of the upstream heating roll 50 is lower than the temperature of the downstream heating roll 50. Therefore, according to the resource circulation system S1, the printed film 40 is suppressed from rapidly thermally shrinking in a high-temperature state, so that the occurrence of wrinkles or the like in the printed film 40 after thermal shrinkage can be suppressed. As a result, according to the resource circulation system S1, the removal of the functional layer in the printed film 40 after thermal shrinkage can be performed more efficiently.

[0057] [5. Other Embodiments] The idea of the above embodiment is not limited to the embodiments described above. Hereinafter, examples of other embodiments to which the idea of the above embodiment can be applied will be described.

[0058] <5-1> In the above-described embodiment, the printing layer removing device 10 physically removed the printing layer 44 and the like of the printed film 40. However, the printing layer removing device 10 does not necessarily have to physically remove the printing layer 44 and the like of the printed film 40. The printing layer removing device 10 may, for example, chemically remove the printing layer 44 and the like of the printed film 40. That is, the printing layer removing device 10 may remove the printing layer 44 and the like from the film by spraying alkaline water onto the printing layer 44 and the like of the printed film 40, for example.

[0059] <5-2> Also, in the above-described embodiment, the printed film 40 was conveyed in a Roll to Roll manner. However, the printed film 40 does not necessarily have to be conveyed in a Roll to Roll manner. The printed film 40 may be, for example, in a sheet form, and each printed film 40 in the sheet form may be conveyed from upstream to downstream by a conveying device such as a belt conveyor.

[0060] <5-3> Also, in the above-described embodiment, the first removing mechanism 110 included a plurality of emery papers 114. However, the configuration for physically treating the printing layer 44 of the printed film 40 in the first removing mechanism 110 is not limited to this. For example, the first removing mechanism 110 may be provided with a blade whose tip is sharpened like a cutting edge instead of the emery paper 114. Also, the blade may not only be fixed, but may also be something that rotates like an electric cutter. Furthermore, a grindstone may be provided instead of the emery paper 114.

[0061] <5-4> Also, in the above-described embodiment, the printing layer removing device 10 included the first removing mechanism 110, the second removing mechanism 120, and the third removing mechanism 130. However, the printing layer removing device 10 does not necessarily have to include all of the first removing mechanism 110, the second removing mechanism 120, and the third removing mechanism 130. On the other hand, additional steps may be provided in order to perform even more precise removal. For example, another removing mechanism that removes the printing layer 44 may be provided upstream of the film heating device 5. The type of mechanism that performs the removal process is not limited as long as the desired removal process can be performed. Known devices other than the file, polishing roll, and blast described in the above embodiment, such as a metal rotary brush, rotary blade, scraper, belt sander, etc., can be used alone or in combination.

[0062] <5-5> Also, in the above-described embodiment, in each of the second removing mechanism 120 and the third removing mechanism 130, physical processing was performed on both sides of the printed film 40. However, in each of the second removing mechanism 120 and the third removing mechanism 130, physical processing does not necessarily have to be performed on both sides of the printed film 40. For example, physical processing may be performed only on the surface of the printed film 40 on which the printing layer 44 is formed.

[0063] As described above, the embodiments of the present invention have been illustratively described. That is, for illustrative purposes, a detailed description and the accompanying drawings have been disclosed. Therefore, among the components described in the detailed description and the accompanying drawings, there may be components that are not essential for solving the problem. Therefore, just because those non-essential components are described in the detailed description and the accompanying drawings, they should not be immediately recognized as essential.

[0064] Moreover, the above-described embodiments are merely illustrative of the present invention in every aspect. Various improvements and modifications are possible within the scope of the present invention. For example, at least a part of the configuration of one of the embodiments may be combined with at least a part of the configuration of any other embodiment. That is, in practicing the present invention, a specific configuration can be appropriately adopted according to the embodiment.

Examples

[0065] Hereinafter, examples of the present invention will be described. Note that the present invention is not limited to the following examples.

[0066] [1. Examples and Comparative Examples] Printed films after heat shrinkage of Examples 1-20 and Comparative Examples 1-4 were produced using printed films with patterns printed thereon. The printed films used in the production of Examples 1-16 and Comparative Examples 1-3 included a printed portion and a transparent portion, the length of the printed portion in the MD direction was 11.6 cm, and the length of the transparent portion in the MD direction was 0.6 cm. Also, the printed films used in the production of Examples 17-20 and Comparative Example 4 included a printed portion and a transparent portion, the length of the printed portion in the MD direction was 14.3 cm, and the length of the transparent portion in the MD direction was 4.1 cm.

[0067] The thickness of the printed films used in the production of Examples 1-20 and Comparative Examples 1-4 was 40 μm. The wet heat shrinkage rates of the printed films used in the production of Examples 1-20 and Comparative Examples 1-4 at each temperature were 18% at 70°C, 34% at 75°C, 47% at 80°C, 56% at 85°C, 64% at 90°C, 68% at 95°C, and 72% at 100°C. Each wet heat shrinkage rate was measured by cutting out a 10 cm square of the printed film and immersing the 10 cm square printed film in warm water at each temperature for 10 seconds.

[0068] In Examples 1-20 and Comparative Examples 1-4, at least any one of the number and set temperature of the heating rolls used for heat shrinkage, the heating distance, and the stretching ratio was different from each other. In each of Examples 1-20 and Comparative Examples 1-4, the number and set temperature of the heating rolls, the heating distance, and the stretching ratio were as shown in Tables 1, 2, and 3 below.

[0069] [Table 1] [Table 2] [Table 3]

[0070] [2. Evaluation Contents] By observing the appearance of the printed film after heat shrinkage in Examples 1-20 and Comparative Examples 1-4, evaluation of wrinkles and edge disturbance was performed.

[0071] [Evaluation of Wrinkles] Regarding the wrinkles of the printed film after heat shrinkage, evaluation was performed according to the following criteria. 0: Innumerable deep folded wrinkles exist. 1: A few deep folded wrinkles remain. 2: Innumerable fine folded wrinkles exist. 3: Innumerable shallow wrinkles exist. 4: A few shallow wrinkles remain. 5: There are irregularities on the surface. 6: It is the degree where there are irregularities due to the pattern. 7: No wrinkles exist.

[0072] [Evaluation of Edge Disturbance] Regarding the edge disturbance of the printed film after heat shrinkage, evaluation was performed according to the following criteria. 0: The folded width at the edge is large, and the edge is greatly meandering. 1: The folded width at the edge is large, and the edge is finely undulating. 2: The folding width at the end is narrow, and the end is finely wavy. 3: The folding width at the end is narrow, and there are no waves or the like at the end. 4: There is no end disturbance.

[0073] [3. Evaluation Results] The results of each evaluation regarding the printed films after heat shrinkage of Examples 1 - 20 and Comparative Examples 1 - 4 were as shown in Tables 4, 5, and 6 below.

[0074] [Table 4] [Table 5] [Table 6] By gradually increasing the heating temperature of the printed film, it was confirmed that wrinkles and end disturbances in the printed film after heat shrinkage were improved. Also, by stretching the printed film in the MD direction during heating of the printed film, it was confirmed that wrinkles and end disturbances in the printed film after heat shrinkage were further improved. [Explanation of Reference Signs]

[0075] 5 Film heating device, 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 Heating roll, 51 Backup roll, 60 Recycled film, 61, 63 Adjacent layers, 62 Intermediate layer, 110 First removal mechanism, 112, 122 Conveyor rolls, 114 Metal file, 120 Second removal mechanism, 124, 126 Polishing rolls, 130 Third removal mechanism, 400 Product part, 410 Ear part, P1 Printing part, P2 Transparent part, S1 Resource circulation system.

Claims

A removal method for removing the printed layer from a printed film including a printed layer, comprising: The printed film is conveyed from upstream to downstream; A first heating mechanism and a second heating mechanism located downstream of the first heating mechanism are provided in the conveyance path of the printed film; A step of manufacturing a printed film after heat shrinkage through heating of the printed film by the first heating mechanism and heating of the printed film by the second heating mechanism; A step of removing the printed layer from the printed film after heat shrinkage; and A removal method in which the temperature of the first heating mechanism is lower than the temperature of the second heating mechanism. **Claim 2** The removal method according to claim 1, wherein the printed film after heat shrinkage is stretched in the conveyance direction of the printed film. **Claim 3** The stretching ratio of the printed film in the conveyance direction of the printed film is less than 2 times, The removal method according to claim 2, wherein the thickness of the printed film becomes 2 times or more through heating of the printed film by the first heating mechanism and heating of the printed film by the second heating mechanism. **Claim 4** The printed film includes a printed portion where the printed layer is formed and a transparent portion where the printed layer is not formed, In the printed film, the printed portion and the transparent portion are alternately formed in the conveyance direction of the printed film. The removal method according to claim 2 or claim 3. **Claim 5** In the step of removing the printed layer from the printed film after heat shrinkage, a physical treatment is performed on the printed film after heat shrinkage to remove the printed layer. The removal method according to any one of claims 1 to 3. **Claim 6** The removal method according to any one of claims 1 to 3, wherein the shrinkage rate of the printed film at the temperature of the first heating mechanism is less than 47%. **Claim 7** There is no other heating mechanism between the first heating mechanism and the second heating mechanism, The removal method according to any one of claims 1 to 3, wherein the difference between the shrinkage rate of the printed film at the temperature of the first heating mechanism and the shrinkage rate of the printed film at the temperature of the second heating mechanism is less than 47%. **Claim 8** A step of manufacturing a printed film from which the printed layer has been removed by using the removal method according to any one of claims 1 to 3. A method for manufacturing a recycled film, comprising a step of manufacturing a recycled film by using a printed film from which the printing layer has been removed.

Images