Ink layer removal method, label recycling method, and plastic product manufacturing method

Abstract

To efficiently remove an ink layer from a label.SOLUTION: A method for removing an ink layer according to an aspect of the present invention includes solution treatment step (S71) for bringing a label piece (71) having an ink layer into contact with an ink removing solution (80). Before the solution treatment step (S71), the label piece (71) is brought into contact with the ink removing solution (80) without pre-heating a label (11).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for removing an ink layer from a label. [Background technology]

[0002] BACKGROUND ART Plastic products such as polyethylene terephthalate (PET) bottles have been widely used in the past. From the viewpoints of resource conservation and environmental protection, there is a demand for the reuse of plastic products such as PET bottles.

[0003] The recycling of PET bottles, especially plastic products, is already widespread. On the other hand, although plastic labels printed with product information are sometimes attached to the body of PET bottles, the recycling of these labels has lagged behind that of PET bottles.

[0004] One of the obstacles to label reuse is the inability to efficiently remove the ink layer from the label, because if the ink layer cannot be efficiently removed from the label, it is not possible to produce usable pellets from the label.

[0005] For example, Patent Document 1 discloses a method in which a shrink label (heat-shrinkable label) is preheated under non-water immersion conditions, and then brought into contact with relatively low-temperature alkaline water to remove the alkaline water-releasable ink layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-350411 Summary of the Invention [Problem to be solved by the invention]

[0007] It is possible to remove the ink layer by using the method described in Patent Document 1. However, the method described in Patent Document 1 requires that the shrink label be preheated to a temperature of about 100°C to cause it to shrink before the ink layer is removed, and there has been a demand for a more efficient method of removing the ink layer.

[0008] An object of one aspect of the present invention is to provide a method for removing an ink layer that can efficiently remove an ink layer from a label. [Means for solving the problem]

[0009] In order to solve the above problem, the method for removing an ink layer according to aspect 1 of the present invention is a method for removing an ink layer from a label having an ink layer, and includes a solution treatment step of contacting the label having the ink layer with an ink removal solution containing a component that dissolves or swells an aqueous ink layer and a component that dissolves or swells an oil-based ink layer, and the label having the ink layer is contacted with the ink removal solution without preheating the label before the solution treatment step.

[0010] In this method, the ink removal solution contains both a component that dissolves or swells the water-based ink layer and a component that dissolves or swells the oil-based ink layer, so that the water-based ink layer and the oil-based ink layer are simultaneously dissolved or swelled in the solution treatment step, making it possible to separate and remove the ink layers from the label.

[0011] Furthermore, in this method, the label having the ink layer is not preheated before the solution treatment step, but is brought into contact with the ink removal solution in the solution treatment step to dissolve or swell the ink layer. This makes it possible to omit the preheating step that was conventionally performed before the ink layer was removed, thereby reducing the number of steps and the energy consumption required for preheating.

[0012] Therefore, the method allows the water-based ink layer and the oil-based ink layer to be efficiently removed from the label.

[0013] In the ink layer removing method according to aspect 2 of the present invention, in the ink removing solution according to aspect 1, the ink removing solution may contain sodium hydroxide, potassium hydroxide, a surfactant, a glycol ether, and a high-boiling point solvent.

[0014] According to the method, by contacting the label with an ink removing solution containing these components, the water-based ink layer and the oil-based ink layer can be dissolved or swelled at normal temperature (room temperature).

[0015] In the ink layer removing method according to aspect 3 of the present invention, in aspect 1 or 2, the temperature of the ink removing solution may be 15°C or higher and lower than 65°C.

[0016] According to the above method, even when the label is a shrink label, the ink layer can be safely and efficiently removed from the shrink label without causing the shrink label to thermally shrink in the solution treatment step. Furthermore, because the treatment can be performed at a lower temperature than conventional alkali treatments, energy consumption can be reduced, resulting in an advantage in terms of energy cost.

[0017] In addition, in the method for removing an ink layer according to aspect 4 of the present invention, in any of aspects 1 to 3, the ink removing solution may be a mixture of an aqueous ink remover containing a component that dissolves or swells the aqueous ink layer and an oil-based ink remover containing a component that dissolves or swells the oil-based ink layer.

[0018] According to the above method, an ink removal solution containing both a component that dissolves or swells a water-based ink layer and a component that dissolves or swells an oil-based ink layer can be easily produced.

[0019] Furthermore, in the method for removing an ink layer according to aspect 5 of the present invention, in any of aspects 1 to 4, after the solution treatment step, a water treatment step may be further included in which the label having the ink layer is brought into contact with water.

[0020] In this method, the adhesiveness of the ink layer is reduced in the solution treatment step, and then the ink layer is removed by contacting the label with water. Therefore, according to this method, the properties of the ink removal solution change little, and the ink removal solution can be efficiently reused.

[0021] In order to solve the above problem, the label recycling method according to aspect 6 of the present invention includes the steps of removing the ink layer from a group of labels including labels having an aqueous ink layer and labels having an oil-based ink layer by the ink layer removal method according to any one of aspects 1 to 5, and producing resin fluff or resin pellets using the labels from which the ink layer has been removed.

[0022] According to the above method, resin fluff or resin pellets can be produced using a label from which the water-based ink layer and the oil-based ink layer have been efficiently removed without preheating.

[0023] In order to solve the above problem, a method for manufacturing a plastic product according to aspect 7 of the present invention includes a step of manufacturing a plastic product using the resin fluff or resin pellets produced by the label recycling method of aspect 6.

[0024] According to the method, plastic products can be manufactured using resin fluff or resin pellets produced from a label from which the water-based ink layer and the oil-based ink layer have been efficiently removed without preheating. [Effects of the Invention]

[0025] According to one aspect of the present invention, the ink layer can be efficiently removed from the label. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram showing an example of a flow of an ink layer removal method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] An embodiment of the present invention will now be described with reference to Fig. 1. However, the following description is merely an example of the method for removing an ink layer according to the present invention, and the technical scope of the present invention is not limited to the illustrated example.

[0028] Figure 1 is a schematic diagram showing an example of the flow of the ink layer removal method according to this embodiment. As shown in Figure 1, the ink layer removal method includes a bottle recovery step S1, a compression step S2, an accumulation step S3, a separation step S4, a sorting step S5, a crushing step S6, a detachment step S7, and a separation / recovery step S8. Each step of the ink layer removal method will be described below with reference to Figure 1.

[0029] <Bottle collection process> First, as shown in S1 of Fig. 1, used PET bottles (items) 10 are collected in a collection box 12. A label 11 having an ink layer is attached to the body of the PET bottle 10. The ink layer is a printing layer on which a design such as a product display is printed.

[0030] The article to which the label 11 is attached is not limited to the PET bottle 10. The article may be any article to which the label 11 is attached and used, and may be a container other than the PET bottle 10 or various molded products other than containers. Similarly, the type of label 11 is not particularly limited, and may be various types of labels such as a shrink label, a wrap label (roll label), and a stretch label.

[0031] The label 11 has, for example, a water-based ink layer or an oil-based ink layer on at least one surface of a film (substrate). The film used for the label 11 is appropriately selected depending on the type of label 11.

[0032] For example, when the label 11 is a shrink label, a heat-shrinkable shrink film is used as the substrate. Examples of shrink films include polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc., styrene-based films made of styrene-butadiene block copolymers, olefin-based films made of olefin-based resins such as polyethylene and polypropylene, and vinyl chloride-based films made of vinyl chloride resin. These may also be foamed films.

[0033] The heat shrinkage rate of the shrink film in at least one direction (the main shrinkage direction) is preferably 30% or more, more preferably 50% or more, from the viewpoint of shrink adhesion to various containers, etc. The thickness of the shrink film can be selected appropriately taking into consideration the handleability of the label 11, and can be, for example, from about 10 μm to about 100 μm, preferably from about 15 μm to about 60 μm. Note that these values ​​for the shrink film are those for the shrink film used to produce the shrink label before it is attached to a container such as a PET bottle 10.

[0034] The film used for label 11 may be a single layer or a laminate of two or more layers. When a laminate of two or more layers is used, the layers may be the same or different. The color of the film is not particularly limited and may be, for example, milky white or transparent.

[0035] To enhance adhesion to the ink layer, the film may be subjected to a surface treatment such as corona discharge treatment, or an anchor coat layer may be provided, as necessary. The anchor coat layer can be formed using a conventionally known anchor coat agent, etc.

[0036] The ink layer is formed of ink that dissolves or swells in the ink removal solution 80 used in the desorption step S7 described below. The ink that forms the ink layer may be either a water-based ink or an oil-based ink.

[0037] As the water-based ink and oil-based ink forming the ink layer, conventionally known inks used for label printing and the like can be used. As the oil-based ink, for example, an ink containing a colorant such as a pigment or dye, a binder resin, an organic solvent, and additives may be blended. Furthermore, as the water-based ink, an ink containing a colorant, a water-soluble or water-dispersible binder resin, additives, and the like may be blended. Examples of additives include lubricants, anti-blocking agents, and anti-settling agents.

[0038] The ink layer can be formed on the surface of the film by, for example, gravure printing, flexographic printing, screen printing, or inkjet printing. The ink layer may be a single layer or multiple layers. The thickness of the ink layer can be appropriately selected depending on the application, and can be, for example, about 0.1 μm to 100 μm.

[0039] <Compression process> Next, as shown in S2 of FIG. 1, the collected PET bottles 10 with the labels 11 attached are compressed to form labeled bales 20.

[0040] <Accumulation process> Next, as shown in S3 of FIG. 1, the labeled bales 20 are sent to a recycling factory 30 and accumulated.

[0041] <Separation process> Next, as shown in S4 of Figure 1, at the recycling plant 30, the labels 11 are removed from the PET bottles 10 in the labeled bale 20, and the PET bottles 10 are separated from the labels 11. The labels 11 separated from the PET bottles 10 may include various types of labels, such as shrink labels, wrap labels, and stretch labels.

[0042] In the illustrated example, shrink labels 11a and wrap labels 11b are shown as labels 11 separated from PET bottles 10. The PET bottles 10 from which the labels 11 have been separated are reused, for example, in existing recycling processes. In particular, the detachment step S7, described below, allows both the water-based ink layer and the oil-based ink layer to be detached. Therefore, the labels 11 separated from the PET bottles 10 in the separation step S4 and sent to the subsequent process do not need to be separated into labels with a water-based ink layer and labels with an oil-based ink layer.

[0043] <Sorting process> Next, the labels 11 are sorted as shown in S5 of Fig. 1. In the sorting step S5, the labels 11 are sorted, for example, by the type of film or material used in the labels 11. The example shown in the figure shows the state in which the labels 11 are sorted by the type of film used in the labels 11, that is, into shrink labels 11a and wrap-around labels 11b, and then collected.

[0044] The labels 11 separated in the sorting step S5 are then separately subjected to the subsequent crushing step S6, detaching step S7, and separation / recovery step S8. As a result, when the film pieces 91 after the ink layer has been removed are collected in the separation / recovery step S8, only film pieces 91 of the same type or material are collected. Therefore, by performing the sorting step S5, it is easy to collect the film pieces 91 by type or material.

[0045] The sorting step S5 is not essential and can be omitted. Also, for example, after film pieces 91 are collected in separation / recovery step S8, film pieces 91 may be sorted by type or material.

[0046] <Crushing process> 1, the label 11 is then crushed by a crusher 70 to produce label pieces 71. In the crushing step S6, prior to the subsequent removal step S7 in which the ink layer is removed from the label 11, the label 11 is crushed into smaller label pieces 71. By performing the removal step S7 in this manner with the label 11 broken into smaller label pieces 71, the ink layer can be efficiently removed from the label pieces 71 in the removal step S7.

[0047] There is no particular limitation on the method for crushing the labels 11. In a detachment step S7 described later, the labels 11 are crushed into pieces of a size (for example, several centimeters square) that allows the ink layer to be efficiently removed from the label pieces 71.

[0048] The crushing step S6 is not essential and can be omitted. In this case, the detaching step S7 is carried out in the state of the label 11.

[0049] <Desorption process> Next, as shown in S7 of Fig. 1, the ink layer is detached and removed from the label piece 71. The detaching step S7 includes a solution treatment step S71 and a water treatment step S72.

[0050] (Solution processing process) The solution treatment step S71 is a step of bringing the label piece 71 into contact with the ink removal solution 80. In this solution treatment step S71, for example, the label piece 71 is placed in the ink removal solution 80 in the solution tank 82 and gently immersed for about 10 minutes. The temperature of the ink removal solution 80 at this time can be normal temperature (approximately 15°C to 25°C) or room temperature (1°C to 30°C). This can reduce the adhesion of the ink layer while preventing complete detachment of the ink layer from the label piece 71 in the ink removal solution 80. Note that the temperature of the ink removal solution 80 means the surface temperature of the label piece 71 during the solution treatment step S71. Furthermore, "gently immersed" means a state in which the ink removal solution 80 is not stirred or is immersed very gently so as not to cause complete detachment of the ink layer.

[0051] The temperature of the ink removal solution 80 in the solution bath 82 may be room temperature, but from the perspective of efficiently removing the ink layer from the label pieces 71, the temperature of the ink removal solution 80 may be higher than room temperature. However, if the label pieces 71 include shrink label pieces, if the temperature of the ink removal solution 80 exceeds 65°C, the shrink film will thermally shrink and the label pieces 71 will curl. It is difficult to remove the ink layer from a curled label piece 71, resulting in a significant decrease in the efficiency of ink layer removal. For this reason, to avoid unintended shrinkage of the label pieces 71, the ink removal solution 80 is preferably kept at a temperature range that does not cause thermal shrinkage of the shrink film, for example, between 15°C and 65°C. This allows the ink layer to be safely and efficiently removed from the label pieces 71 without thermally shrinking the shrink label in the solution treatment step S71.

[0052] In this way, the ink removal solution 80 dissolves or swells the ink layer within a temperature range that does not cause thermal shrinkage of the shrink film. This makes it possible to omit the preheating step that was previously performed before removing the ink layer, thereby reducing the number of steps and the energy consumption required for preheating.

[0053] The ink removal solution 80 is alkaline with a pH of approximately 11 to 14, and contains components that dissolve or swell the water-based ink layer and the oil-based ink layer at room temperature. In other words, the ink removal solution 80 contains both a component that dissolves or swells the water-based ink layer and a component that dissolves or swells the oil-based ink layer. Therefore, the water-based ink layer and the oil-based ink layer can be simultaneously dissolved or swelled, allowing the ink layers to be separated and removed from the label piece 71.

[0054] The ink removal solution 80 may contain, for example, sodium hydroxide, potassium hydroxide, a surfactant, a glycol-based solvent (e.g., glycol ether), a high-boiling point solvent (e.g., polymeric alcohol), etc. By contacting the label with an ink removal solution containing these components, the water-based ink layer and the oil-based ink layer can be dissolved or swelled at room temperature.

[0055] Alternatively, the ink removing solution 80 may be a mixture obtained by mixing an aqueous ink remover containing a component that dissolves or swells the aqueous ink layer with an oil-based ink remover containing a component that dissolves or swells the oil-based ink layer. This makes it possible to easily produce an ink removing solution 80 that contains both a component that dissolves or swells the aqueous ink layer and a component that dissolves or swells the oil-based ink layer.

[0056] The aqueous ink remover is not particularly limited as long as it dissolves or swells the aqueous ink layer at room temperature. The aqueous ink remover may be, for example, a commercially available aqueous ink remover for removing aqueous ink, or may be a commercially available agent (removal agent, cleaning agent, etc.) for purposes other than removing aqueous ink.

[0057] An example of such a water-based ink remover that can be suitably used is a product called "Ventilation Fan Range Cleaner PRO" (manufactured by Rinrei Co., Ltd.) Table 1 below shows an example of the composition and ingredients of a water-based ink remover (product called "Ventilation Fan Range Cleaner PRO") that can be suitably used in producing the ink remover solution 80.

[0058] [Table 1] As shown in Table 1, the aqueous ink remover can include, for example, water, a glycol-based solvent (glycol ether), an amphoteric surfactant (alkyl betaine), sodium hydroxide, potassium hydroxide, and a sequestering agent.

[0059] The oil-based ink remover is not particularly limited as long as it dissolves or swells the oil-based ink layer at room temperature. The oil-based ink remover may be, for example, a remover for oil-based ink that is commercially available for removing oil-based ink, or may be a chemical (remover, cleaner, etc.) that is commercially available for purposes other than removing oil-based ink.

[0060] A suitable example of such an oil-based ink remover solution is "PAINTSOLV-W," a product manufactured by Infinity Co., Ltd. Table 2 below shows an example of the composition and ingredients of an oil-based ink remover (product name "PAINTSOLV-W") that can be suitably used to produce the ink remover solution 80.

[0061] [Table 2] As shown in Table 2, the oily ink remover can contain, for example, a high boiling point solvent (polymer alcohol-based solvent), a nonionic surfactant (lauryl glucoside), and the like.

[0062] By mixing an aqueous ink remover containing the components shown in Table 1 with an oil-based ink remover containing the components shown in Table 2 in a ratio of, for example, 1:9, it is possible to suitably produce an ink remover solution 80 that dissolves or swells aqueous ink layers and oil-based ink layers at room temperature.

[0063] (Water treatment process) In the water treatment step S72, the label piece 71 having the ink layer is brought into contact with water 84 after the solution treatment step S71. In the water treatment step S72, the label piece 71 removed from the solution bath 82 is immersed in water 84 in a water bath 86 and agitated. In the illustrated example, the water 84 in which the label piece 71 is immersed is agitated by a screw 88 rotatably mounted on the bottom of the water bath 86. By agitating the water 84 in which the label piece 71 is immersed, the ink layer is separated from the label piece 71 in the water 84. For example, if the label piece 71 has an oil-based ink layer, the label piece 71 is separated into a film piece 91 and an ink coating 93. If the label piece 71 has a water-based ink layer, the label piece 71 is also separated into a film piece 91 and an ink coating 93. If the label piece 71 has a water-based ink layer, the ink layer may dissolve and disperse in the water 84.

[0064] The temperature of the water 84 in the water tank 86 is not particularly limited, but from the viewpoint of avoiding unintended shrinkage of the label piece 71, it is preferably about room temperature (around 27° C.).

[0065] Thus, in the removal step S7, first, in the solution treatment step S71, the label piece 71 is gently immersed in the ink removal solution 80. This reduces the adhesion between the ink layer and the label piece 71 while preventing complete separation of the ink layer from the label piece 71 in the ink removal solution 80. At this time, the ink removal solution 80 dissolves or swells the water-based ink layer and the oil-based ink layer at room temperature, so the pre-heating step that the label 11 traditionally undergoes before the ink layer is removed can be omitted. Then, in the subsequent water treatment step S72, the label piece 71 is immersed in water 84 and agitated, allowing the ink layer to be removed from the label piece 71.

[0066] The ink removing solution 80 after the label pieces 71 have been immersed in may be disposed of as waste liquid, or may be reused as the ink removing solution 80. When the desorption step S7 includes the water treatment step S72 as in this embodiment, there is little change in the properties of the ink removing solution 80. This allows the ink removing solution 80 to be reused more efficiently. Examples of changes in the properties of the ink removing solution 80 include the inclusion of a large amount of ink layer.

[0067] Furthermore, the water treatment step S72 is not essential and can be omitted. In this case, in the solution treatment step S71, the label pieces 71 are immersed in the ink removal solution 80 in the solution tank 82 and stirred. This allows the ink layer to be separated and removed from the label pieces 71.

[0068] <Separation / recovery process> Next, as shown in S8 of Figure 1, the film piece 91 and the ink coating 93 in the water tank 86 are separated and collected. For example, a first net 90 with relatively large openings collects the film piece 91 after the ink layer has detached from the label piece 71, and a second net 92 with relatively small openings collects the ink coating 93, which is smaller than the film piece 91. The ink coating 93 is a film formed by finely dividing the oil-based ink layer removed from the label piece 71 in the detachment step S7.

[0069] The film pieces 91 collected by the first net 90 can then be reused, for example, in the production of labels, as a plastic raw material for producing plastic products such as resin fluff or resin pellets (resin repellets) made by repelletizing the film pieces 91. The film pieces 91 can also be reused as labels by mixing them into the raw material for new labels. Meanwhile, the ink coating 93 collected by the second net 92 can be reused, for example, in a thermal recycling process.

[0070] The water-based ink detached from the label piece 71 in the detachment step S7 dissolves and disperses in water 84. Therefore, when recovering water-based ink or water-based ink and oil-based ink, precipitation, centrifugation, solvent evaporation, extraction, filtration, coagulation separation, or other recovery methods can be used in the separation / recovery step S8.

[0071] <Summary> As described above, the ink layer removal method of this embodiment is a method for removing an ink layer from a label 11 having an ink layer, and includes a solution treatment step S71 in which the label 11 having an ink layer is brought into contact with an ink removal solution 80 containing a component that dissolves or swells an aqueous ink layer and a component that dissolves or swells an oil-based ink layer, and the label 11 having an ink layer is brought into contact with the ink removal solution 80 without pre-heating the label 11 having the ink layer before the solution treatment step S71.

[0072] In the ink layer removal method according to this embodiment, the ink removal solution 80 contains both a component that dissolves or swells the water-based ink layer and a component that dissolves or swells the oil-based ink layer. Therefore, in the solution treatment step S71, the water-based ink layer and the oil-based ink layer are simultaneously dissolved or swelled, making it possible to separate and remove the ink layers from the label 11.

[0073] Furthermore, in the ink layer removal method according to this embodiment, the label 11 having the ink layer is not preheated before the solution treatment step S71, but is brought into contact with the ink removal solution 80 in the solution treatment step S71 to dissolve or swell the ink layer. This makes it possible to omit the preheating step that was conventionally performed before removing the ink layer, thereby reducing the number of steps and the energy consumption required for preheating.

[0074] Furthermore, the ink layer removal method according to this embodiment can be applied to various types of labels other than shrink labels, such as wrap-around labels and stretch labels, and can remove water-based ink layers and oil-based ink layers from various types of labels. Therefore, for example, there is no need to process labels with water-based ink layers and labels with oil-based ink layers separately, and ink layers can be removed from a group of labels that contain a mixture of these types of labels.

[0075] Therefore, according to this embodiment, a method for removing an ink layer that can efficiently remove a water-based ink layer and an oil-based ink layer from the label 11 can be realized.

[0076] The ink layer removal method according to this embodiment makes it possible to omit the preheating step, thereby reducing the energy consumption required for preheating. Furthermore, it also makes it possible to efficiently recycle labels, which have traditionally been primarily subjected to thermal recycling. This will contribute to the achievement of the Sustainable Development Goals (SDGs). [Example]

[0077] An example of the present invention will be described below. In this example, the ink layer removal rate by the ink layer removal method according to the present invention was verified.

[0078] First, a 50 μm thick PET shrink film (Hishipet® LX-18S, manufactured by Mitsubishi Chemical Corporation) was used as a raw sheet to prepare a shrink film measuring 50 μm thick, 15 cm high (width), and 24 cm long (circumference). A first ink layer, a second ink layer, and a third ink layer were laminated in this order onto this shrink film using aqueous inks to produce a cylindrical shrink label (label 11) with an aqueous ink layer. Furthermore, a first ink layer, a second ink layer, and a third ink layer were laminated in this order onto the same shrink film using oil-based inks to produce a cylindrical shrink label (label 11) with an oil-based ink layer.

[0079] Next, a shrink label with a water-based ink layer and a shrink label with an oil-based ink layer were individually applied to a cylindrical PET bottle with an outer diameter of 54 mm, and the bottle was then heat-shrunk to produce a shrink-labeled PET bottle. The shrinkage rate of the shrink label was about 30%, and the area of ​​the attached shrink label was about 70% of the area of ​​the original shrink label. The shrink label was then peeled off the PET bottle, and the PET bottle and shrink label were separated (separation step S4).

[0080] Next, the shrink label peeled off from the PET bottle was crushed to prepare approximately square shrink label pieces (label pieces 71) measuring 40 mm in length and 40 mm in width (crushing step S6).

[0081] Next, the shrink label pieces were placed in the ink remover solution 80 in the solution tank 82 and gently immersed for approximately 10 minutes at room temperature (27°C) (solution treatment step S71). A 500 ml beaker was used for the solution tank 82. The ink remover solution 80 was prepared by placing 30 ml of a water-based ink remover (product name "Ventilation Fan Range Cleaner PRO") and 270 ml of an oil-based ink remover (product name "PAINTSOLV-W") into the solution tank 82 and mixing them.

[0082] Next, the shrink label strip removed from the solution tank 82 was immersed in 300 ml of water 84 in a water tank 86 and stirred at 200 rpm for 5 minutes using a magnetic stirrer (water treatment step S72). A 500 ml beaker was used for the water tank 86.

[0083] Next, shrink label pieces were collected from the water tank 86 using a first net 90 with relatively large openings, and the ink layer remaining on each shrink label piece was confirmed. The results showed that both the water-based ink layer and the oil-based ink layer had been removed from each shrink label piece by 70% to 100%.

[0084] This example confirmed that the ink layer removal method according to the present invention can efficiently remove water-based ink layers and oil-based ink layers from shrink labels without preheating.

[0085] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0086] 11, 11a, 11b: Label, 80: Ink removal solution 84:Water S71: Solution treatment process S72: Water treatment process

Claims

1. A method for removing an ink layer from a label having an ink layer, comprising the steps of: a solution treatment step in which a label having an ink layer is brought into contact with an ink removal solution containing a component that dissolves or swells a water-based ink layer and a component that dissolves or swells an oil-based ink layer within a temperature range in which thermal shrinkage of the label does not occur, while suppressing detachment of the ink layer, thereby dissolving or swelling the ink layer and reducing adhesion between the label and the ink layer; a water treatment step in which, after the solution treatment step, the label having the ink layer is immersed in water and agitated to remove the ink layer from the label; A method for removing an ink layer, comprising contacting the label having the ink layer with the ink removing solution without preheating the label before the solution treating step.

2. 2. The method for removing an ink layer according to claim 1, wherein the ink removal solution contains sodium hydroxide, potassium hydroxide, a surfactant, a glycol ether, and a high-boiling point solvent.

3. 3. The method for removing an ink layer according to claim 1, wherein the temperature of the ink removing solution is 15°C or higher and lower than 65°C.

4. 4. The method for removing an ink layer according to claim 1, wherein the ink removing solution is a mixture of an aqueous ink remover containing a component that dissolves or swells the aqueous ink layer and an oil-based ink remover containing a component that dissolves or swells the oil-based ink layer.

5. A step of removing ink layers from a group of labels including labels having water-based ink layers and labels having oil-based ink layers by the method of removing an ink layer according to any one of claims 1 to 4; a step of producing resin fluff or resin pellets using the label from which the ink layer has been removed; How to recycle the label, including:

6. A method for manufacturing a plastic product, comprising the step of manufacturing a plastic product using the resin fluff or the resin pellets produced by the label recycling method according to claim 5.

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