Removal method, method for producing recycled resin raw materials, method for producing recycled film, and removal apparatus

Abstract

This invention provides a removal method that can efficiently remove the printed layer from a heat-shrinkable film. [Solution] A removal method is provided for removing a printed layer from a heat-shrinkable film that includes a printed layer. This removal method includes a heating step of heating the heat-shrinkable film so that it shrinks, and a removal step of removing the printed layer from the heat-shrinkable film by irradiating the heat-shrinkable film that has shrunk in the heating step with energy rays.

Description

Technical Field

[0001] The present invention relates to a removal method for removing a printing layer from a heat-shrinkable film, a method for producing a recycled resin raw material, a method for producing a recycled film, and a removal apparatus.

Background Art

[0002] In recent years, the environmental burden from the procurement to the disposal of fossil-derived raw materials for plastic products has become a global issue. Therefore, resource circulation such as recycling plastic products that have been conventionally discarded as resources has attracted attention. For example, Patent Document 1 discloses a method for producing a heat-shrinkable film using fluff and pellets obtained from a packaging material having a printing layer as a starting material. In Patent Document 1, the printing ink is peeled off from the packaging material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In many film products, a printing layer is laminated on a resin film body. When producing recycled products using waste materials of such films, various components contained in the printing layer may become foreign substances and deteriorate the quality of the recycled products. For example, when transparency is required for recycled products, the colorants contained in the printing layer may reduce the transparency of the recycled products. Therefore, when recycling waste materials of films, it may be important to firmly remove the printing layer from the waste materials of the films in advance.

[0005] An object of the present invention is to provide a removal method and apparatus capable of efficiently removing the printed layer from a heat-shrinkable film. Another object of the present invention is to produce a recycled resin raw material with less foreign matter contamination originating from the printed layer using a heat-shrinkable film from which the printed layer has been removed by such a removal method, and further to produce a recycled film with less foreign matter contamination originating from the printed layer using such a recycled resin raw material. [Means for solving the problem]

[0006] Item 1. A method for removing a printed layer from a heat-shrinkable film containing a printed layer, A heating step of heating the heat-shrinkable film so that the heat-shrinkable film shrinks, A removal step is to remove the printed layer from the heat-shrinkable film by irradiating the heat-shrinkable film, which has been heat-shrinked in the heating step, with energy rays. A removal method that includes this.

[0007] Item 2. An additional removal step for further removing the printing layer remaining on the heat-shrinkable film after the removal step. It further includes, The aforementioned additional removal step is (a) A physical processing step to remove the printed layer by applying a physical treatment to the printed layer. (b) A chemical treatment step to remove the printed layer using a desorbing solution. (c) Washing step of washing the heat shrinkable film The process includes at least one of the three steps (a) to (c), The removal method described in item 1.

[0008] Item 3. In the removal process, at least one of an ultraviolet laser, an infrared laser, and a xenon lamp is used to irradiate the energy rays. The removal method described in item 1 or 2.

[0009] Item 4. In the removal step, the energy beam is irradiated using a laser set to be focused away from the printed layer contained in the heat-shrinkable film. A removal method as described in any of items 1 to 3.

[0010] Item 5. To manufacture recycled resin raw materials using the heat-shrinkable film from which the printed layer has been removed by any of the removal methods described in Items 1 to 4 as at least part of the raw materials. A method for producing recycled resin raw materials, including those mentioned above.

[0011] Item 6. Manufacturing a recycled film using the recycled resin raw material produced by the manufacturing method described in Item 5 as at least part of the raw material. A method for manufacturing recycled film, including the following.

[0012] Item 7. A removal apparatus for removing a printed layer from a heat-shrinkable film containing a printed layer, A heating mechanism for heating the heat-shrinkable film so that the heat-shrinkable film shrinks, An irradiation mechanism removes the printed layer from the heat-shrinkable film by irradiating the heat-shrinkable film, which has been heat-shrinked by the heating mechanism, with energy rays. A removal device equipped with the following features. [Effects of the Invention]

[0013] The present invention provides a removal method and apparatus capable of efficiently removing the printed layer from a heat-shrinkable film. Furthermore, using the heat-shrinkable film from which the printed layer has been removed by such a removal method, a recycled resin raw material with less foreign matter contamination originating from the printed layer can be manufactured, and further, a recycled film with less foreign matter contamination originating from the printed layer can be manufactured using such a recycled resin raw material. [Brief explanation of the drawing]

[0014] [Figure 1] A schematic block diagram showing a resource recycling system according to one embodiment. [Figure 2]Cross-sectional view of a waste film according to an embodiment. [Figure 3] Side view showing the configuration of a removal device according to an embodiment. [Figure 4] Perspective view showing the configuration of a heating mechanism according to an embodiment.

Mode for Carrying Out the Invention

[0015] Hereinafter, an embodiment of the present invention will be described 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, the drawings are schematically drawn with appropriate omissions or exaggerations of the subject for ease of understanding.

[0016] [1. Configuration of Resource Recycling System] In recent years, the environmental load from the procurement to the disposal of fossil-derived raw materials for plastic products has become a global problem. As a means to address such problems, resource recycling has attracted attention. FIG. 1 is a diagram schematically showing a resource recycling system S1 that uses the removal method, the method for producing the recycled resin raw material 3, and the method for producing the recycled film 4 according to the present embodiment. As shown in FIG. 1, in the resource recycling system S1, a waste material of a film (hereinafter referred to as a waste film) 1 is recycled to produce a recycled resin raw material 3. Various resin products can be produced from the recycled resin raw material 3. For example, a new film (hereinafter referred to as a recycled film) 4 is produced. The waste film 1 is, for example, a packaging material in the form of a film or a label that can be used in various fields such as food, beverages, pharmaceuticals, medical products, chemicals, cosmetics, toiletries, industrial products, and agricultural products. The recycled film 4 can also be the same type of packaging material.

[0017] The waste film 1 according to this embodiment is a heat-shrinkable film in its state before heat shrinkage. Although not limited to this, the waste film 1 according to this embodiment is a uniaxially oriented film that shrinks mainly in the width direction (TD; Transverse Direction). The heat shrinkage rate of the waste film 1 in the main shrinkage direction can be appropriately selected depending on the application, but it is preferably 30% or more, and more preferably 50% or more, when immersed in 90°C hot water for 10 seconds.

[0018] Figure 2 is a cross-sectional view of the waste film 1 according to this embodiment. The waste film 1 has a resin film body 11 and a printed layer 12 laminated on the film body 11. Here, an example is shown in which the printed layer 12 is laminated on both sides of the film body 11, but the printed layer 12 may be laminated on only one side of the film body 11. The film body 11 is a transparent or translucent film, although it is not limited to this. The printed layer 12 is a layer for applying a pattern to the film body 11 and contains a coloring component (colorant) such as ink. The pattern consists of, for example, a design, letters, symbols (for example, a barcode), or a combination thereof. The printed layer 12 is formed, for example, by using a gravure printing plate.

[0019] The waste film 1 can be, for example, unused products, intermediate processed products, leftover products, defective products, prototypes, or discarded products. The waste film 1 can be, for example, a product film having a product portion used for packaging the target product and a film edge continuous with the edge of the product portion. Alternatively, the waste film 1 may be a product portion cut from such a product film, or it may be a film edge. The waste film 1 may be, for example, a lead film used for printing registration (pattern alignment). The film edge is separated from the product portion by cutting the product film along the boundary line between the product portion and the film edge before the product portion is shipped. The product portion has a printing layer 12 printed on it, for example, information related to the target product. The film edge has a printing layer 12 printed on it, for example, information for checking the printing status on the product portion. The product portion is used for packaging various containers such as plastic containers, glass containers, and paper containers. The product portion shrinks when heated and is attached to the container by, for example, conforming to the outer surface of the container along its outer shape. The product portion is, for example, formed into a cylindrical shape, placed over the container so as to cover the container from the outside, then heat-shrunk and attached to the container. The product portion is formed into a cylindrical shape by overlapping both ends of the TD and sealing the overlapped portion in the MD (Machine Direction). In this case, when the product portion is attached to the container as a label, typically the TD of the product portion corresponds to the lateral direction of the container, and the MD of the product portion corresponds to the vertical direction of the container. If the waste film 1 is a cylindrical film, it is preferable to cut the waste film 1 or otherwise unfold it into a sheet before removing the printing layer 12, which will be described later. The waste film 1 according to this embodiment is a long film and is wound up for storage and handling purposes and managed in the form of a film roll (winding body) R1.

[0020] The printed layer 12 may have an inner coat layer, an overcoat layer, etc., laminated on it. The inner coat layer is formed, for example, to improve the slipperiness between the product and the labeling device that attaches the film as a label to the product. The overcoat layer is formed, for example, to reduce scratches on the outward-facing surface of the label attached to the product. The inner coat layer and the overcoat layer are formed, for example, in the printing process of the design.

[0021] The thickness of the film body 11 is not particularly limited and can be appropriately selected depending on the application, but is preferably 10 μm or more, more preferably 12 μm or more, and even more preferably 15 μm or more. Furthermore, the thickness of the film body 11 is preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. The film body 11 may be a single layer or a multilayer. The film body 11 may contain layers mixed with different types of resins, or may contain multiple layers, each containing a different type of resin. Furthermore, each layer constituting the film body 11 may contain components other than resin. Each layer constituting the film body 11 may contain various additives. Examples of additives include antiblocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, and fluorescent whitening agents.

[0022] Examples of the types of resins contained in the film body 11 include polyolefin resins, polystyrene resins, polyamide resins, and polyester resins. Examples of polyolefin resins include polypropylene, polyethylene, and cyclic polyolefin resins. Examples of polypropylene resins include binary or ternary random copolymers with propylene as the main component and ethylene, butene, and α-olefin as copolymer components. Specifically, α-olefins are preferably composed of ethylene, 1-butene, 1-hexene, 1-octene, etc., and may contain two or more types of α-olefins. Furthermore, the polypropylene resin may be a mixture of different propylene-α-olefin random copolymers. Examples of polyethylene 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-olefins are used. Examples of α-olefins include propylene, 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 polyolefin resins include (a) copolymers of ethylene or propylene with cyclic olefins (e.g., norbornene and its derivatives, or tetracyclododecene and its derivatives), (b) ring-opened polymers of the cyclic olefin or copolymers with α-olefins, (c) hydrogenated polymers of (b), and (d) graft-modified products of (a) to (c) using unsaturated carboxylic acids and their derivatives. The above-mentioned cyclic olefins are not particularly limited, and specific examples 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 resins include homopolymers of styrene monomers and copolymers consisting of styrene monomers and other monomers (conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Specifically, these include aromatic vinyl hydrocarbon-conjugated diene copolymers, mixed resins of aromatic vinyl hydrocarbon-conjugated diene copolymers and aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymers, and rubber-modified impact-resistant polystyrene. More specifically, these include styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), and highly branched polystyrene. Examples of polyamide resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the above-mentioned aliphatic polyamides include aliphatic nylon and its copolymers, specifically polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sevacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), etc. Examples of polyester resins include those obtained by condensation polymerization of a dicarboxylic acid component and a diol component. The types of dicarboxylic acid components mentioned above are not particularly limited, and examples include 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, decamethylenecarboxylic acid, their anhydrides, and lower alkyl esters.The types of diol components listed above are not particularly limited, and include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5- Examples include aliphatic diols such as hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, and polytetramethylene ether glycol; 2,2-bis(4-hydroxycyclohexyl)propane; alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane; and alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol.

[0023] The thickness of each printed layer 12 is not particularly limited and can be appropriately selected depending on the application, but is preferably 1 μm or more and 15 μm or less, more preferably 2 μm or more and 10 μm or less, and even more preferably 4 μm or more and 8 μm or less.

[0024] Referring again to Figure 1, the resource recycling system S1 comprises a removal device 10, a recycled resin raw material manufacturing device 20, and a film manufacturing device 30. The removal device 10 is a device that removes the printing layer 12 from the waste film 1. In order to use the removal device 10, first, a film roll R1 on which the waste film 1 is wound is prepared and set in the removal device 10. Next, the waste film 1 is unwound from the film roll R1, the unwound waste film 1 is processed, and a processed film 2 is produced. The processed film 2 is obtained by removing the printing layer 12 from the waste film 1. The printing layer 12 is removed in order to prevent its components from mixing with the recycled resin raw material 3, thereby reducing the functionality of the recycled resin raw material 3 and the recycled film 4 produced from the recycled resin raw material 3. Typically, the processed film 2 does not have the printing layer 12 and consists only of the film body 11, but a part of the printing layer 12 may remain.

[0025] In the resource recycling system S1, recycled resin raw material 3 is further produced from the processed film 2 by the recycled resin raw material manufacturing device 20. The recycled resin raw material manufacturing device 20 uses the processed film 2 produced by the removal device 10 as at least a portion of the raw material to produce the recycled resin raw material 3. The recycled resin raw material 3 is a resin raw material obtained by processing the processed film 2 into a shape that is easy to handle when producing recycled film 4 from the processed film 2. Specifically, the recycled resin raw material 3 can be in the form of fluff 3a, pellets 3b, powder 3c, granules 3d, etc. There is a type of pellet 3b that is produced by heating and melting the raw material and then solidifying it, but granules 3d are different from such types of pellets 3b; they are lumps that are compressed and solidified without heating and melting the powdered raw material. Furthermore, recycled resin raw materials 3, such as fluff 3a, powder 3c, or granules 3d, which are manufactured without heating and melting the raw materials, may be more susceptible to thermal degradation than recycled resin raw materials 3, such as the pellets 3b described above, which are manufactured by heating and melting the raw materials and then solidifying them, because they do not undergo excessive thermal history such as heating and melting during processing.

[0026] The processed film 2 can be processed into fluff 3a by, for example, using a known crusher, shredder, cutter, etc., to finely chop the processed film 2. The size (area) of fluff 3a is 500 mm². 2 The following is preferable: 300mm 2 The following is more preferable: 200mm 2 The following is even more preferable: 100 mm 2 The following are particularly preferable.

[0027] The processed film 2 can be processed into pellets 3b using, for example, a known resin pellet manufacturing machine. For example, fluff 3a can be supplied to an extruder, heated and melted in the extruder, then extruded through a die, and the extruded material can be cut into an appropriate shape to produce pellets 3b. Note that pellets 3b may be manufactured not only from the processed film 2 (fluff 3a) but also from virgin resin raw materials and / or chemically recycled resin raw materials (hereinafter referred to as virgin resin raw materials, etc.). In this case, virgin resin raw materials, etc., are supplied to the extruder in addition to fluff 3a.

[0028] The processed film 2 can be processed into powder 3c by, for example, the following method. First, the fluff 3a is immersed in a suitable solvent to dissolve the resin components contained in the fluff 3a in the solvent, thereby generating a solution containing the resin components. Then, the resin components are precipitated by cooling the solution, mixing it with a poor solvent, and / or heating the solution to evaporate the solvent. After that, the precipitated resin components is dried to produce powder 3c.

[0029] The processed film 2 can be processed into granules 3d, for example, by drying the resin component precipitates described above while stirring them under vacuum. Alternatively, the granules 3d can also be manufactured using a known granulator. In this case, the resin component precipitates or powder 3c described above can be fed into the granulator.

[0030] In the resource recycling system S1, recycled film 4 is further manufactured from recycled resin raw material 3 by the film manufacturing apparatus 30. The film manufacturing apparatus 30 is a device that manufactures recycled film 4 using recycled resin raw material 3 manufactured by the recycled resin raw material manufacturing apparatus 20 as at least a part of the raw material. As a processing method for recycled film 4, known film formation methods can be used. For example, recycled resin raw material 3 may be supplied to an extruder, heated and melted in the extruder, and then extruded from a die. At this time, a laminated film can be manufactured by co-extrusion. After molding, the recycled film 4 may be stretched as appropriate to impart heat shrinkability and processed into a heat shrinkable film. In addition, a printed layer may be laminated onto the recycled film 4. The recycled film 4 is also typically a long film, and from the viewpoint of storage and handling, it is preferable to wind it up and manage it in the form of a film roll R4.

[0031] The recycled film 4 may be manufactured using not only recycled resin raw material 3 but also virgin resin raw material, etc. In this case, for example, virgin resin raw material, etc., is supplied to the extruder in addition to recycled resin raw material 3. The recycled film 4 can be constructed in the same way as the film body 11 included in the waste film 1 in terms of material, layer structure, and thickness. Therefore, the above description of the film body 11 also applies to the recycled film 4. The recycled film 4 may be single-layered or multi-layered. If the recycled film 4 is multi-layered, recycled resin raw material 3 may be used in at least one layer included in the recycled film 4, and at least another layer may be composed only of virgin resin raw material, etc., and recycled resin raw material 3. The recycled film 4 can be used to make packaging materials such as packaging bags or tubular labels that are used to cover containers, etc., by bonding both ends together to form a tube.

[0032] [2. Configuration of the removal device] The configuration of the removal device 10 will be described in detail below with reference to Figure 3. Figure 3 is a side view showing the configuration of the removal device 10. Below, the details of each part included in the removal device 10 will be described in accordance with the flow of the processing steps for the waste film 1 (flow of the method for removing the printed layer 12).

[0033] The removal device 10 comprises a heating mechanism 40, an irradiation mechanism 50, a chemical treatment mechanism 60, a physical treatment mechanism 70, a washing mechanism 80, and a drying mechanism 90. These mechanisms 40, 50, 60, 70, 80, and 90 are arranged in this order from upstream to downstream along the transport path of the waste film 1. Although not limited to this, the removal device 10 according to this embodiment is a device that processes the waste film 1 while transporting it roll to roll, and further comprises an unwinding machine 91, a winding machine 92, and a guide roller 95.

[0034] The unwinding machine 91 is located at the upstream end of the removal device 10 and is a device that unwinds the waste film 1 from the film roll R1. The unwinding machine 91 has an axis that rotatably holds the film roll R1. When the film roll R1 set on the axis of the unwinding machine 91 rotates, the waste film 1 is unwound from the unwinding machine 91 and transported downstream. Numerous guide rollers 95 are installed in the transport path. At least some of the guide rollers 95 may be drive rollers. The waste film 1 is transported to the winding machine 92 located at the downstream end of the removal device 10, guided by these guide rollers 95. In this process, the waste film 1 is processed into a treated film 2 from which the printed layer 12 has been removed by passing through a heating mechanism 40, an irradiation mechanism 50, a chemical treatment mechanism 60, a physical treatment mechanism 70, a washing mechanism 80, and a drying mechanism 90 in that order. The treated film 2 is wound into the form of a film roll R2 by the winding machine 92. The winding machine 92 has a shaft (typically a drive shaft) that rotatably holds the film roll R2.

[0035] The heating mechanism 40 heats the waste film 1 so that it shrinks due to heat. Figure 4 is a perspective view showing the configuration of the heating mechanism 40. As shown in Figure 4, the heating mechanism 40 has a heating roll 41 and a backup roll 42. The heating roll 41 is heated and becomes hot. The waste film 1 unwound from the unwinding machine 91 is wrapped around the hot heating roll 41 and begins to shrink due to contact with it. As a result, the length of the waste film 1 in the width direction is shortened, and wrinkles, curls, and undulations (hereinafter referred to as wrinkles, etc.) occur in the waste film 1. Also, the thickness of the waste film 1 increases due to this heat shrinkage. The backup roll 42 is configured to press the heat-shrunk waste film 1 against the heating roll 41. The heat-shrunk waste film 1 is sandwiched between the heating roll 41 and the backup roll 42, which smooths out the wrinkles, etc. caused by the heat shrinkage. Therefore, the waste film 1 can be made to a nearly flat state almost simultaneously with the heat shrinkage. If no wrinkles or other defects occur in the waste film 1 due to processing conditions such as the temperature and speed of the heating roll 41, a backup roll 42 may not be necessary. The processing conditions in the heating mechanism 40 are adjusted as appropriate so that the waste film 1 undergoes a predetermined thermal shrinkage. For example, the temperature of the heating roll 41 is preferably 60°C to 150°C, more preferably 70°C to 120°C, and the rotation speed (unwinding speed) is preferably about 3m / min to 500m / min.

[0036] As for the heating method in the heating mechanism 40, any method is acceptable, not limited to the method using the heating roll 41, as long as it can heat-shrink the waste film 1 to a predetermined state. For example, methods such as immersion in hot water or oil such as glycerin, passing through a hot air tunnel, or applying superheated steam can be appropriately selected. For example, in the case of immersing a long piece of waste film 1 in hot water, the heating mechanism 40 is configured to heat-shrink the waste film 1 by passing it through a water tank containing hot water for about 5 to 30 seconds while conveying the waste film 1 from upstream to downstream in a roll-to-roll manner. The temperature of the hot water is, for example, 60°C or higher, preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. Furthermore, it is preferable that the thickness of the waste film 1 increases by 1.3 times or more through the heat treatment in the heating mechanism 40, more preferably by 2 times or more, even more preferably by 2.5 times or more, and even more preferably by 3 times or more.

[0037] The waste film 1 that has passed through the heating mechanism 40 is sent to the irradiation mechanism 50. The irradiation mechanism 50 removes the printed layer 12 from the waste film 1 by irradiating the waste film 1, which has been heat-shrunk in the heating mechanism 40, with energy rays (active energy rays). The energy rays may be irradiated from only one side of the waste film 1, or from both sides. It is preferable that the energy rays be irradiated from the side of the film body 11 on which the printed layer 12 is laminated. Therefore, if the printed layer 12 is provided on both sides of the film body 11, it is preferable to irradiate from both sides, and if the printed layer 12 is provided on only one side of the film body 11, it is preferable to irradiate from only that one side. The irradiation mechanism 50 damages the printed layer 12 contained in the waste film 1 by irradiating with energy rays and removes the printed layer 12 from the film body 11.

[0038] The type of energy ray is not particularly limited as long as it can emit enough energy to remove the printed layer 12, and may be, for example, ultraviolet, infrared, or visible light. Alternatively, the type of energy ray may be an electron beam or radiation. The irradiation mechanism 50 may consist of a laser device or a lamp whose irradiation area does not converge. A flash lamp can be used as the lamp. Particularly preferred examples include using at least one of an ultraviolet laser, an infrared laser, and a xenon lamp as the irradiation mechanism 50. The wavelength of light emitted by the ultraviolet laser is preferably 100 nm to 400 nm, more preferably 340 nm to 380 nm, for example 355 nm. The wavelength of light emitted by the infrared laser is 780 nm or more, preferably 1000 nm to 11000 nm, for example 1064 nm or 10.6 μm. The xenon lamp can generate light with wavelengths in the ultraviolet, visible, and infrared regions.

[0039] If the irradiation mechanism 50 is a laser device, the entire width of the waste film 1 may be irradiated with energy rays by rapidly reciprocating the energy ray source in the TD direction and irradiating in small increments. Alternatively, or in addition to this, the energy ray source may be reciprocated in the MD direction and irradiated in small increments. Furthermore, the irradiation range for a single irradiation may be widened by configuring the energy ray source from multiple elements arranged in at least one direction of TD and MD. If the irradiation mechanism 50 is a xenon lamp, since it is a surface light source, it is preferable that its irradiation range includes the entire width of the waste film 1. Furthermore, irradiation may be performed in small increments using a xenon lamp according to the speed of the waste film 1. In addition, lasers with different wavelengths of light (for example, an ultraviolet laser with a wavelength of 355 nm and an infrared laser with a wavelength of 10.6 μm) may be used in combination, or a laser and a flash lamp may be used in combination.

[0040] If the irradiation mechanism 50 is a laser device, the laser device may be set to focus on the printed layer 12 contained in the waste film 1, or it may be set to be out of focus from the printed layer 12. In the former case, higher energy can be applied to the printed layer 12. On the other hand, in the latter case, the irradiation range of the energy beam in a single irradiation on the printed layer 12 is wider compared to the former case. Therefore, the energy beam can be efficiently directed onto the printed layer 12, and the printed layer 12 can be efficiently removed.

[0041] As described above, in this embodiment, the waste film 1 is heated and thermally shrunk by the heating mechanism 40 before the printed layer 12 is removed by the irradiation mechanism 50. Now, let's consider the case where the waste film 1 is irradiated with energy rays by the irradiation mechanism 50 before thermal shrinkage, without prior thermal shrinkage by the heating mechanism 40. In this case, while the energy rays are being irradiated, the waste film 1 begins to shrink due to the heat generated by the energy rays, causing wrinkles and other defects to appear on the waste film 1. If energy rays are irradiated while the waste film 1 is undergoing thermal deformation, it may be hindered from evenly hitting the printed layer 12 with energy rays. Furthermore, even after thermal deformation is complete, if the waste film 1 has wrinkles or other defects, i.e., if the waste film 1 is not flat, it will still be difficult for the energy rays to evenly hit the printed layer 12. As a result, a problem of incomplete removal may occur, where a large amount of the printed layer 12 remains. In addition, the energy rays irradiated from the irradiation mechanism 50 are high-powered enough to remove the printed layer 12. Therefore, the waste film 1 may melt due to the energy rays, potentially causing damage such as holes or tears in the waste film 1. These problems can be particularly noticeable when the waste film 1 is thin.

[0042] In this embodiment, the waste film 1 is heated in the heating mechanism 40 before it is sent to the irradiation mechanism 50. Therefore, since the thickness of the waste film 1 has increased by the heating mechanism 40 by the time it reaches the irradiation mechanism 50, the problem of damage to the waste film 1 due to irradiation with energy rays is less likely to occur. Also, since the waste film 1 has already undergone thermal shrinkage by the time it reaches the irradiation mechanism 50, the amount of new thermal shrinkage that occurs in the irradiation mechanism 50 is small. Therefore, wrinkles and other defects are less likely to occur in the waste film 1, which is transported from the heating mechanism 40 in a nearly flat state, and the energy rays can be irradiated onto the waste film 1 in a flatter state. As a result, it becomes possible to evenly apply the energy rays to the printed layer 12, the problem of remaining material after removal is less likely to occur, and the printed layer 12 can be efficiently removed from the waste film 1.

[0043] In the irradiation mechanism 50, irradiating the waste film 1 in a flatter state with energy rays is particularly advantageous when the irradiation mechanism 50 is a laser device. That is, in order to thoroughly remove the printed layer 12 without damaging the waste film 1 by laser irradiation, it is important to precisely control the positional relationship between the printed layer 12 and the focal point. This applies whether the focus is on the printed layer 12 or whether the focus is shifted away from the printed layer 12. In this respect, when the waste film 1 is flat, it becomes easier to control the positional relationship between the printed layer 12 and the focal point.

[0044] In this embodiment, after the printed layer 12 is removed by the irradiation mechanism 50, additional removal of the printed layer 12 is performed by the chemical treatment mechanism 60, the physical treatment mechanism 70, and the washing mechanism 80. That is, the printed layer 12 remaining on the waste film 1 after passing through the irradiation mechanism 50 is further removed by the chemical treatment mechanism 60, the physical treatment mechanism 70, and the washing mechanism 80.

[0045] First, processing is carried out in the chemical processing mechanism 60. The chemical processing mechanism 60 removes the printed layer 12 from the waste film 1 using a desorption solution. In this embodiment, the chemical processing mechanism 60 is configured to spray the desorption solution onto the surface of the waste film 1 where the printed layer 12 remains (this may be one side of the waste film 1 or both sides). The desorption solution is, for example, a basic solvent. As a result, the desorption solution reacts with the coloring components contained in the printed layer 12, and the printed layer 12 is peeled off from the film body 11. More specifically, when the desorption solution is a basic solvent, the basic components of the basic solvent bond with the functional groups of the resin contained in the coloring components, inhibiting adhesion between the film body 11 and the coloring components, and as a result, the coloring components are detached from the film body 11. As the desorption solution, for example, water containing an inorganic base can be used. Specific examples of inorganic bases include sodium hydroxide and potassium hydroxide. These inorganic bases are preferably contained at a concentration of 0.1 to 10% by mass relative to the total volume of the eluent. If the eluent is a basic solvent, the pH of the eluent should be greater than 7, but preferably 8 or higher, and preferably 11 or lower, considering the ease of treating the waste liquid generated by spraying the eluent.

[0046] The processing method in the chemical processing mechanism 60 is not limited to the method of spraying the desorbing liquid. For example, a method of immersing the waste film 1 in a solvent capable of dissolving the printed layer 12, or a method of applying such a solvent to the printed layer 12 can be appropriately selected.

[0047] By the time the chemical processing mechanism 60 is reached, the printed layer 12 contained in the waste film 1, even if it remains, is usually damaged to some extent by the irradiation of energy rays. For example, scratches that reach the film body 11 are formed in the printed layer 12. As a result, the desorption liquid can easily reach the interface between the film body 11 and the printed layer 12, making it easier to peel the printed layer 12 from the film body 11. Consequently, even if the desorption liquid is a weakly alkaline basic solvent, the printed layer 12 can be thoroughly removed.

[0048] Next, processing is carried out by the physical processing mechanism 70. Note that the order of processing by the chemical processing mechanism 60 and processing by the physical processing mechanism 70 may be reversed. The physical processing mechanism 70 removes the printed layer 12 by applying physical processing to the printed layer 12. The physical processing mechanism 70 according to this embodiment is configured to physically polish the surface of the waste film 1 on which the printed layer 12 remains (this may be one side of the waste film 1 or both sides). The physical processing mechanism 70 includes, for example, polishing tools such as a metal file or a polishing roll. For example, the waste film 1 is transported with the polishing tool in contact with the printed layer 12, thereby scraping the printed layer 12 off the film body 11. The removed waste of the printed layer 12 generated in this process is sucked up by, for example, a suction mechanism (not shown), collected, and discarded.

[0049] As for the processing method in the physical processing mechanism 70, any method can be adopted as long as the printed layer 12 can be removed from the film body 11 by mechanical action such as rubbing, scraping, or peeling. For example, a method using equipment such as a metal rotating brush, a rotating blade, a scraper, a belt sander, or a blasting device (including a wet blasting device) can be appropriately selected.

[0050] Even at the stage when it reaches the physical processing mechanism 70, the printed layer 12 remaining on the waste film 1 is usually damaged to some extent by irradiation with energy rays (and processing in the chemical processing mechanism 60) and has become brittle. Therefore, the printed layer 12 can be removed from the film body 11 relatively easily by mechanical actions such as rubbing, scraping, or peeling.

[0051] Next, processing is carried out in the cleaning mechanism 80. The cleaning mechanism 80 cleans the waste film 1. In this embodiment, the cleaning mechanism 80 is configured to spray cleaning liquid onto the surface of the waste film 1 on which the printed layer 12 remains (this may be one side of the waste film 1 or both sides). This washes away the printed layer 12 remaining on the surface of the waste film 1 as debris. The printed layer 12 remaining on the waste film 1 even after reaching the cleaning mechanism 80 is usually damaged to some extent by irradiation with energy rays (and processing in the chemical processing mechanism 60 and the physical processing mechanism 70) and has become brittle, so it is washed away relatively easily as debris.

[0052] The waste film 1 is processed in a chemical treatment mechanism 60, a physical treatment mechanism 70, and a washing mechanism 80, and then sent to a drying mechanism 90. The drying mechanism 90 is configured to blow air (preferably warm air) onto at least one side of the waste film 1. This dries the surface of the waste film 1.

[0053] The processed film 2 that has passed through the washing mechanism 80 is wound up by the winding machine 92 to become a film roll R2. The film roll R2 recovered from the winding machine 92 is supplied to the recycled resin raw material manufacturing apparatus 20, where recycled resin raw material 3 is manufactured.

[0054] When an overcoat layer is laminated on the printing layer 12, the overcoat layer is removed from the waste film 1 along with the printing layer 12 when the waste film 1 is processed by the irradiation mechanism 50, the chemical treatment mechanism 60, and the physical treatment mechanism 70. The overcoat layer may contain (meth)acrylic acid ester resins that can cause a decrease in haze of the recycled film 4, but if the overcoat layer is removed together with the printing layer 12, this effect can be reduced.

[0055] In this embodiment, the waste film 1 is heated before the removal of the printed layer 12, increasing its thickness and thus improving the strength of the waste film 1. Therefore, even if tension is applied to the waste film 1 for transport, it is possible to suppress the situation in which the waste film 1 breaks when the printed layer 12 is removed. As a result, the printed layer 12 can be continuously removed while the waste film 1 is transported, so the printed layer 12 can be efficiently removed from the waste film 1. In addition, because the length of the waste film 1 in the width direction is shortened due to the thermal shrinkage of the waste film 1, it is possible to suppress the enlargement of each of the irradiation mechanism 50, chemical treatment mechanism 60, physical treatment mechanism 70, washing mechanism 80, and drying mechanism 90. From the viewpoint of the above effects, the thermal shrinkage rate of the waste film 1 in the main shrinkage direction in the heating mechanism 40 is preferably, for example, 30% to 95%, more preferably 40% to 90%, and even more preferably 50% to 85%.

[0056] [3. Features] In the above embodiment, the waste film 1 is heated and thermally shrunk in the heating mechanism 40 before being sent to the irradiation mechanism 50. Therefore, since the thickness of the waste film 1 has increased by the heating mechanism 40 by the time it reaches the irradiation mechanism 50, the problem of damage to the waste film 1 due to irradiation with energy rays is less likely to occur. Also, since the waste film 1 has already thermally shrunk by the time it reaches the irradiation mechanism 50, the amount of new thermal shrinkage that occurs in the irradiation mechanism 50 is small. Therefore, wrinkles and other defects are less likely to occur in the waste film 1 that is transported from the heating mechanism 40 in a nearly flat state in the irradiation mechanism 50, and energy rays can be irradiated onto the waste film 1 in a flatter state. As a result, it becomes possible to evenly apply energy rays to the printed layer 12, the problem of remaining material after removal is less likely to occur, and the printed layer 12 can be efficiently removed from the waste film 1.

[0057] [4. Variant] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0058] <4-1> In the above embodiment, the waste film 1 was transported roll to roll. However, the waste film 1 does not necessarily have to be transported roll to roll. The waste film 1 may be in sheet form, for example, and each sheet of waste film 1 may be transported from upstream to downstream by a transport device such as a belt conveyor. In the physical processing step, the waste film 1 in sheet form may be subjected to a process such as stirring with media (abrasive material) or agitating with vibration such as ultrasonic waves to remove the printed layer 12. Alternatively, the waste film 1 may be shredded or pulverized. In this case, the shredded or pulverized waste film 1 may be irradiated with energy rays, and then the printed layer 12 may be removed by a physical process such as stirring with media (abrasive material) or a chemical process such as immersion in an alkaline solution.

[0059] <4-2> The chemical treatment mechanism 60, the physical treatment mechanism 70, and the cleaning mechanism 80 may all be omitted, and the printed layer 12 may be removed by the irradiation mechanism 50 alone. Alternatively, parts of the chemical treatment mechanism 60, the physical treatment mechanism 70, and the cleaning mechanism 80 may be omitted. In this case, the drying mechanism 90 may also be omitted as appropriate. [Explanation of Symbols]

[0060] 1. Waste film 11 Film body 12 printing layer 2. Processed film 3 Recycled resin raw materials 3a Fluff 3b Pellet 3c powder 3d granules 4. Recycled film 10 Removal device 20 Recycled resin raw material manufacturing equipment 30 Film manufacturing equipment 40 Heating mechanism 41 Heating Roll 42 Backup Roles 50 Irradiation mechanism 60 Chemical Processing Mechanisms 70 Physical Processing Mechanisms 80 Cleaning mechanism 90 Drying mechanism 91 Unwinding machine 92 Winder 95 Guide Roller S1 Resource Recycling System R1, R2, R4 film rolls

Claims

1. A method for removing a printed layer from a heat-shrinkable film containing a printed layer, A heating step of heating the heat-shrinkable film so that the heat-shrinkable film shrinks, A removal step is to remove the printed layer from the heat-shrinkable film by irradiating the heat-shrinkable film, which has been heat-shrinked in the heating step, with energy rays. A removal method that includes this.

2. An additional removal step to further remove the printing layer remaining on the heat-shrinkable film after the removal step described above. It further includes, The aforementioned additional removal step is (a) A physical processing step to remove the printed layer by applying a physical treatment to the printed layer. (b) A chemical treatment step to remove the printed layer using a desorbing solution. (c) Washing step of washing the heat shrinkable film The process includes at least one of the three steps (a) to (c), The removal method according to claim 1.

3. In the removal process, the energy rays are irradiated using at least one of an ultraviolet laser, an infrared laser, and a xenon lamp. The removal method according to claim 1 or 2.

4. In the removal step, the energy beam is irradiated using a laser that is set to be out of focus from the printed layer contained in the heat-shrinkable film. The removal method according to claim 1 or 2.

5. A recycled resin raw material is produced by using the heat-shrinkable film from which the printed layer has been removed by the removal method described in claim 1 or 2 as at least a part of the raw material. A method for producing recycled resin raw materials, including those mentioned above.

6. A recycled film is manufactured using the recycled resin raw material produced by the manufacturing method described in claim 5 as at least a part of the raw material. A method for manufacturing recycled film, including the following.

7. A removal apparatus for removing a printed layer from a heat-shrinkable film containing a printed layer, A heating mechanism for heating the heat-shrinkable film so that the heat-shrinkable film shrinks, An irradiation mechanism removes the printed layer from the heat-shrinkable film by irradiating the heat-shrinkable film, which has been heat-shrinked by the heating mechanism, with energy rays. A removal device equipped with the following features.

Images