Recycling method

Abstract

To provide a recycling method capable of suppressing reduction in productivity.SOLUTION: A recycling method comprises: a peeling step S02 for peeling an adhesive label 10 from a container 20 while bringing the container adhered with the adhesive label into contact with a solution containing water of 50°C or higher; a separation step S03 for separating the adhesive label peeled in the peeling step from the container; a crush step S04 for crushing the container from which the adhesive label is separated in the separation step; and a granulation step S05 for granulating a container piece crushed in the crush step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a recycling method. [Background technology]

[0002] In order to create a recycling-oriented society, it is important that plastic containers and bottles are collected and recycled. Due to growing social demand, numerous recycling methods are being considered. The recycling process can be broadly divided into collection, sorting, crushing, washing, and granulation, and with improvements to make each process more efficient, it is expected that the importance of resource recycling will continue to increase in the future.

[0003] These plastic containers and bottles have adhesive labels attached to indicate the contents and to add design features. However, in the material recycling process, the labels must be removed due to concerns that they may become foreign matter and reduce the quality of the recycled pellets.

[0004] BACKGROUND ART There are known adhesive labels whose adhesiveness is significantly reduced when washed with an alkali, and which peel off naturally (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-184508 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the alkaline cleaning process for adhesive labels is generally carried out after the container crushing process. Because the adhesive labels that peel off during the alkaline cleaning process are made of a softer material than the containers, they are easily crushed into pieces smaller than the container fragments during the crushing process. At this time, some of the small label fragments peeled off in the alkaline cleaning equipment end up being discharged from the cleaning container along with the alkaline cleaning solution. The alkaline cleaning solution is filtered to remove foreign matter before being reused for alkaline cleaning. However, the small peeled label fragments in the alkaline cleaning solution clog the filter, resulting in frequent filter replacement and a significant reduction in productivity.

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a recycling method that can suppress a decrease in productivity. [Means for solving the problem]

[0008] The above object of the present invention can be achieved by the following means.

[0009] (1) a peeling step of peeling the adhesive label from the container while bringing the container to which the adhesive label is attached into contact with a solution containing water at 50°C or higher; a separating step of separating the adhesive label and the container peeled off in the peeling step; a crushing step of crushing the container from which the adhesive label has been separated in the separating step; A recycling method comprising a granulation step of granulating the container fragments crushed in the crushing step.

[0010] (2) a peeling step of bringing a container to which an adhesive label is attached into contact with a solution containing water at 50°C or higher, and then peeling the adhesive label from the container; a separating step of separating the adhesive label and the container peeled off in the peeling step; a crushing step of crushing the container from which the adhesive label has been separated in the separating step; A recycling method comprising a granulation step of granulating the container fragments crushed in the crushing step.

[0011] (3) The recycling method according to (1) or (2), wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water.

[0012] (4) The recycling method according to (1) or (2), wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with water at 50°C to 90°C.

[0013] (5) The recycling method according to (1) or (2), wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with a detergent.

[0014] (6) The recycling method according to (1) or (2), wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water and a detergent.

[0015] (7) The recycling method according to (1) or (2), wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water, a surfactant, and a solvent. [Effects of the Invention]

[0016] According to the recycling method described above, after the adhesive label is peeled off from the container, the container is crushed. This prevents label fragments from clogging the mesh used to remove foreign matter during cleaning, dramatically reducing the frequency of filter and dust box replacement. This provides a recycling method that can prevent a decrease in productivity. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an adhesive label attached to a container. [Figure 2] 1 is a flowchart showing a recycling method according to the present embodiment. [Figure 3] FIG. 2 is a schematic diagram showing a peeling device. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional proportions in the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0019] First, the configurations of the adhesive label 10 and the container 20 will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing how the adhesive label 10 is attached to the container 20.

[0020] As shown in FIG. 1, the adhesive label 10 has a substrate 11 and an adhesive layer 12.

[0021] The substrate 11 may be a paper substrate or a film substrate.

[0022] It is preferable to use a paper base material that is not defibrated. Examples of paper base materials include kraft paper, fine paper, gloss paper (for example, fine paper that has been gloss-coated on one side), glassine paper, and parchment paper. Here, "not defibrated" refers to paper whose wet strength has been increased by polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, or the like.

[0023] Examples of the film substrate that can be used include films made of at least one resin selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyvinyl chloride, polystyrene, polyurethane, polycarbonate, polyamide, polyimide, polyetherimide, poly(meth)acrylic acid ester, polybutene, polybutadiene, polymethylpentene, acrylic urethane, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ABS resin, ionomer resin, and various thermoplastic elastomers, as well as laminate films of one or more types selected from these.

[0024] The film substrate may contain, as needed, stabilizers, lubricants, fillers, colorants, processing aids, softeners, metal powders, antifogging agents, ultraviolet absorbers, antioxidants, antistatic agents, flame retardants, etc. Examples of stabilizers that may be used include Ba-Zn-based, Cd-Ba-based, and Sn-based stabilizers, and these may be used in combination with epoxidized soybean oil, epoxy resins, etc. Examples of softeners that may be used include ethylene / vinyl acetate copolymers and ethylene / vinyl acetate / carbon monoxide copolymers.

[0025] The film substrate may be a stretched film such as a uniaxially stretched film or a biaxially stretched film, or may be a non-stretched film, or may be formed by a casting method or the like using a processing material.

[0026] The thickness of the substrate may be set as appropriate, but in consideration of alkali peelability and mechanical strength of the label, it is preferably 10 to 500 μm, more preferably 20 to 100 μm.

[0027] The adhesive layer 12 can be an adhesive that dissolves when brought into contact with a solution containing water at 50°C or higher, or an adhesive that causes the adhesive label 10 to separate from the container 20 when brought into contact with a solution containing water at 50°C or higher.

[0028] The solution to be brought into contact with the adhesive layer 12 can be alkaline cleaning water, water at 50°C to 90°C (preferably 70 to 85°C), detergent, alkaline cleaning water and detergent, or a solution consisting of alkaline cleaning water, surfactant, and detergent.

[0029] As an adhesive that dissolves upon contact with alkaline cleaning water, an adhesive disclosed in JP-A-06-184508 can be used, and an adhesive obtained by appropriately balancing a (meth)acrylic acid alkyl ester, a (meth)acrylic acid ester having an ether bond, and a hydrophilic unsaturated monomer containing a carboxyl group and / or a hydroxyl group and performing metal chelate crosslinking can be used.

[0030] The adhesive disclosed in JP 2023-55613 A can be used as the adhesive that causes the adhesive label 10 to separate from the container 20 when brought into contact with alkaline cleaning water. Specifically, the adhesive layer is formed from an adhesive composition containing an acrylic copolymer.

[0031] The pressure-sensitive adhesive composition contains an acrylic copolymer obtained by copolymerizing a monomer mixture containing more than 0.5% by mass of an acid group-containing vinyl monomer.

[0032] The monomer mixture contains alkyl (meth)acrylate as the main monomer component, and optionally contains a monomer copolymerizable with alkyl (meth)acrylate (copolymerizable monomer). Here, the main component refers to 50% by mass or more of the monomers, preferably 65% ​​by mass or more, and more preferably 85% by mass or more.

[0033] The alkyl group of the alkyl (meth)acrylate may be any of a linear, branched, or cyclic alkyl group. The alkyl group is preferably an alkyl group having 1 to 24 carbon atoms, and more preferably an alkyl group having 1 to 18 carbon atoms.

[0034] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, considering stripping with alkaline water, it is preferable to use n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate as the alkyl (meth)acrylate, and it is more preferable to use 2-ethylhexyl (meth)acrylate because this can shorten the stripping time with alkaline water, and it is even more preferable to use 2-ethylhexyl acrylate. In one preferred embodiment, the monomer mixture contains 50 mass% or more of n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate (preferably 2-ethylhexyl (meth)acrylate, more preferably 2-ethylhexyl acrylate), and further, it is preferable that the monomer mixture contains 50 to 99.5 mass%, 70 to 97 mass%, and 80 to 95 mass%, respectively, of n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate (preferably 2-ethylhexyl (meth)acrylate, more preferably 2-ethylhexyl acrylate). When n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate is used, the amount is preferably 50 to 99.5 mass %, more preferably 70 to 97 mass %, and even more preferably 80 to 95 mass %, based on the total amount of alkyl (meth)acrylate and acid group-containing vinyl polymer.

[0035] From the viewpoint of adhesiveness, it is preferable to use methyl (meth)acrylate in combination with n-butyl (meth)acrylate and / or 2-ethylhexyl (meth)acrylate, and it is more preferable to use methyl methacrylate in combination. The content of methyl (meth)acrylate is preferably 0.5 to 20 mass%, more preferably 1 to 20 mass%, even more preferably 1 to 15 mass%, and even more preferably 5 to 15 mass%, based on the total amount of monomers.

[0036] The adhesive that dissolves in water, detergent, alkaline cleaning water and detergent, and a solution consisting of alkaline cleaning water, surfactant, and detergent at 50°C to 90°C (preferably 70 to 85°C), or the adhesive that causes the adhesive label 10 to separate from the container 20 when brought into contact with water, detergent, alkaline cleaning water and detergent, and a solution consisting of alkaline cleaning water, surfactant, and detergent at 50°C to 90°C, is not particularly limited, and examples that can be used include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, styrene-diene block copolymer adhesives, vinyl alkyl ether adhesives, etc. The above adhesives may be used alone or in combination of two or more.

[0037] The container 20 is not particularly limited, but examples thereof include plastic containers made of polyester, polyolefin, etc. Plastic containers also include refill pouches.

[0038] Next, the recycling method according to this embodiment will be described with reference to Figures 2 and 3. Figure 2 is a flowchart showing the recycling method according to this embodiment. Figure 3 is a schematic diagram showing a peeling device 90.

[0039] As shown in Figure 2, the recycling method of this embodiment includes a collection step S01 of collecting containers 20 having adhesive labels 10 attached thereto, a peeling step S02 of peeling the adhesive labels 10 from the containers 20 by contacting the containers 20 having the adhesive labels 10 attached thereto with alkaline cleaning water using a peeling device 90 shown in Figure 3, a separation step S03 of separating the adhesive labels 10 from the containers 20, a crushing step S04 of crushing the containers 20, and a granulation step S05 of granulating the crushed container pieces.

[0040] As the peeling device 90, a known device can be used, for example, the separation device disclosed in Japanese Patent Application Laid-Open No. 2011-5848.

[0041] As shown in Figure 3, the peeling device 90 has an input section 91 into which a container 20 with an adhesive label 10 attached is input, a polygonal rotating body 92 arranged horizontally, a plurality of rotating blades 93 arranged in parallel to the polygonal rotating body 92 at a predetermined inclination angle, a main body section 94 having the polygonal rotating body 92 inside, a needle section 95 installed inside the main body section 94, and a discharge section 96 from which the adhesive label 10 and the container 20 are discharged.

[0042] The main body 94 is filled with alkaline cleaning water. The alkaline cleaning water is preferably filled up to a height of at least half of the main body 94.

[0043] In the peeling step S02, the container 20 to which the adhesive label 10 is attached is placed into the peeling device 90, and is brought into contact with alkaline cleaning water, thereby reducing the adhesive strength of the adhesive label 10 to the container 20. Then, in a state in which the adhesive strength has been reduced, the container 20 to which the adhesive label 10 is attached comes into contact with the rotary blade 93 and the needle portion 95, thereby allowing the adhesive label 10 to be completely peeled off from the container 20. The adhesive label 10 and the container 20 are discharged from the discharge portion 96.

[0044] In the separation step S03, the adhesive labels 10 and the containers 20 peeled off in the peeling step S02 are separated. Specifically, the adhesive labels 10 and the containers 20 discharged from the discharge unit 96 are washed with water, dried, and then separated from each other. As a method for separation, for example, a method of separating them by wind or the like utilizing the difference in their own weight can be mentioned.

[0045] In the crushing step S04, the container 20 is crushed into container fragments using a known crusher. The crusher may be, for example, the device disclosed in Japanese Patent Application Laid-Open No. 10-15495. The crusher has a plurality of screws with cutters on the outer periphery. The container 20 is fed into the crusher, whereby the container 20 is crushed into container fragments.

[0046] In the granulation process S05, the container pieces are granulated using a known granulator. A granulator is a machine that processes the container pieces into pellets (granules) by heating, semi-melting, and solidifying them. Processing them into pellets improves productivity and handling. In the granulator, granulation is carried out in the following order: raw material is fed into the feed hopper, dehydrated and semi-melted in the conveying and drying section, ejected from the die and cut, and finally pelletized.

[0047] As described above, the recycling method according to this embodiment includes a peeling step S02 in which the container 20 to which the adhesive label 10 is attached is brought into contact with a solution containing water at 50°C or higher, while peeling the adhesive label 10 from the container 20; a separation step S03 in which the adhesive label 10 peeled in the peeling step S02 is separated from the container 20; a crushing step S04 in which the container 20 from which the adhesive label 10 was separated in the separation step S03 is crushed; and a granulation step S05 in which the crushed container fragments in the crushing step S04 are crushed. According to this recycling method, the container 20 is crushed after the adhesive label 10 is peeled from the container 20. This prevents label fragments from clogging the mesh used to remove foreign matter during washing, dramatically reducing the frequency of filter and dust box replacement. Therefore, a recycling method capable of suppressing a decrease in productivity can be provided.

[0048] The recycling method according to the present invention has been described above through the embodiments, but the present invention is not limited to the above-described embodiments and can be modified in various ways within the scope of the claims.

[0049] For example, in the above-described embodiment, in the peeling step S02, the container 20 to which the adhesive label 10 is attached is brought into contact with a solution containing water at 50° C. or higher, while the adhesive label 10 is peeled off from the container 20. However, in the peeling step S02, the container 20 to which the adhesive label 10 is attached may be brought into contact with a solution containing water at 50° C. or higher, and then the adhesive label 10 may be peeled off from the container 20. [Explanation of symbols]

[0050] 10 adhesive labels, 11 base material, 12 adhesive layer, 20 containers, S01 Recovery process, S02 Peeling process, S03 Separation process, S04 Crushing process, S05 Granulation process.

Claims

1. a peeling step of peeling the adhesive label from the container while bringing the container to which the adhesive label is attached into contact with a solution containing water at 50°C or higher; a separating step of separating the adhesive label and the container peeled off in the peeling step; a crushing step of crushing the container from which the adhesive label has been separated in the separating step; A recycling method comprising a granulation step of granulating the container fragments crushed in the crushing step.

2. a peeling step of bringing a container to which an adhesive label is attached into contact with a solution containing water at 50°C or higher, and then peeling the adhesive label from the container; a separating step of separating the adhesive label and the container peeled off in the peeling step; a crushing step of crushing the container from which the adhesive label has been separated in the separating step; A recycling method comprising a granulation step of granulating the container fragments crushed in the crushing step.

3. 3. The recycling method according to claim 1, wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water.

4. 3. The recycling method according to claim 1, wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with water at 50°C to 90°C.

5. 3. The recycling method according to claim 1, wherein the container with the adhesive label attached thereto is brought into contact with a detergent in the peeling step.

6. 3. The recycling method according to claim 1, wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water and a detergent.

7. 3. The recycling method according to claim 1, wherein in the peeling step, the container to which the adhesive label is attached is brought into contact with alkaline cleaning water, a surfactant, and a solvent.

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