Plastic component separation / recovery method for composite plastic waste product

Abstract

Provided is a separation / recovery method for a composite plastic waste product, the method characterized by: including at least a first step (A) for separating 3P-based plastic components including polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P-based plastic components; and the first step (A) being either (1) a step for separating 3P-based plastics from plastics other than 3P-based plastics by means of specific gravity using a glycol-based solvent which is a solvent for solvolysis of plastics other than 3P-based plastics and is not a solvent for solvolysis of 3P-based plastics, or (2) a step for using a ketone-based solvent or xylene-based solvent, which is a solvent for dissolving 3P-based plastics and is not a solvent for dissolving plastics other than 3P-based plastics, to dissolve and separate 3P-based plastics at said dissolution temperature. Also provided is a composite plastic waste product chemical recycling method which preferably includes the second step (B). The second step, which follows the first step, is either (1) a step for using a glycol-based solvent that is a solvent for solvolysis of residual plastics other than 3P-based plastics, discharging from the system, and separating by rapid cooling in the same glycol-based solvent, or (2) a step for subjecting residual plastics other than 3P-based plastics to solvent separation using a glycol-based solvent at a temperature close to the boiling point of 180-280ºC. Depending on the type thereof, it is possible to aim for complete separation of the composite plastic waste products by using: a combination of step (1) in the first step (A) and step (1) in the second step (B); a combination of step (1) in the first step (A) and step (2) in the second step (B); a combination of step (2) in the first step (A) and step (1) in the second step (B); and a combination of step (2) in the first step (A) and step (2) in the second step (B).

Description

Separation and recovery of plastic components from composite plastic waste

[0001] The present invention relates to a method for separating and recovering plastic components from composite plastic waste composed of a plurality of different types of plastics.

[0002] Recycling methods for waste plastics can be broadly divided into: 1) "material recycling," which uses physical processes to create products from waste plastics; 2) "thermal recycling," which reuses waste plastics for power generation and thermal incineration at waste incineration facilities, as a cement raw material, or as solid fuel; and 3) "chemical recycling," which uses chemical methods to regenerate resins and produce pyrolysis oil from waste plastics. As of 2023, thermal recycling accounts for approximately 62%, material recycling accounts for approximately 21%, and chemical recycling accounts for approximately 4%, with chemical recycling accounting for the smallest proportion due to the impact of recovery costs. However, despite the significant value of recovering target components from waste plastics, plastic waste is typically manufactured from a composite of multiple plastics (e.g., the lid, label, and container of a PET container are made of different plastics), plastic and metal composites (e.g., aluminum pouches), plastic and cellulose fiber composites (e.g., clothing and disposable diapers), and plastic reinforced with glass fiber, carbon fiber, etc., resulting in a complex and diverse range of uses. Therefore, while PET container caps and labels are separated and collected, aluminum pouches, disposable diapers, and household plastic waste are often incinerated, making it difficult to selectively extract target components from composite plastic waste. Therefore, one method for sorting and separating composite plastics involves using ethylene glycols as a reaction initiator to form a reaction solvent with the dissolving plastics, and separating the plastic components into three types: floating plastic components, dissolved plastic components, and sinking plastic components (Patent Document 1). Another method has been proposed: using heavy oil as a solvent to heat and dissolve organic combustibles, followed by pyrolysis of the organic combustibles in the heavy oil, and then cracking and purifying the separated pyrolysis products (Patent Document 2). Another method has also been proposed: using water, alcohol, glycol, or ammonia as a solvent containing at least one OH group to decompose and extract PET components from plastic waste using a solvolysis method (Patent Document 3).However, currently, only plastic containers (PET) and other plastics are collected separately, and PET-based plastics are recovered and reused. Although efforts are underway to increase the recycling rate of disposable plastics (so-called single-use plastics) to 25% by 2025 and to achieve a recovery rate of 90% by 2029, no effective method has been implemented, and most plastics are currently incinerated or landfilled. Therefore, in order to prevent disposable plastics (single-use plastics) from becoming plastic waste, there is a trend toward banning their use worldwide, including in Europe. This is due to concerns about the impact of microplastics being ingested into the food chain and affecting ecosystems, which is a problem of marine plastics.

[0003] Patent Document 1: Japanese Patent No. 6050834 Patent Document 2: Japanese Patent Laid-Open No. 2023-112971 Patent Document 3: Japanese Patent Publication No. 2023-521994

[0004] Therefore, the inventors have considered the reasons why separation of components from composite plastic waste has not been put to practical use in conventional methods. While it is essential to separate so-called 3P plastic components from other plastic components without leaving any residue, when molten plastics (Patent Document 1) or heavy oil (Patent Document 2) are used as solvents, it is difficult to separate the so-called 3P plastics from the solvent components discharged together with the 3P plastics. That is, in the conventional first method (Patent Document 1), the reaction solvent is molten plastic, so when recovering the so-called 3P plastics, the molten plastics are mixed in, making separation difficult and resulting in contaminated waste. On the other hand, when heavy oil is used as the solvent in the second method (Patent Document 2), it is difficult to separate the 3P plastics from the heavy oil discharged together with the 3P plastics. Furthermore, the third method (Patent Document 3) not only separates the plastic components but also attempts to dissolve and separate the PET component into its constituent components by solvolysis, which is thought to be difficult to implement. Therefore, the first object of the present invention is to completely separate so-called 3P plastic components such as PP (polypropylene), PE (polyethylene), and PS (polystyrene) from other plastic components and recover the solvent, thereby enabling the effective utilization of the 3P components. The second object is to provide a method for simply separating the 3P plastics from the non-3P plastics that have been separated and recovered, rather than separating the components (see Patent Document 3). Furthermore, when cellulose, metals, and reinforcing fibers are contained in addition to the plastic components, the third object is to provide a method for separating and recovering the plastic components from the other components.

[0005] The inventors conducted extensive research into the selective separation of 3P plastics from composite plastic waste. First, they found that by using glycols, which are used as solvolysis agents for non-3P plastics, instead of decomposition solvents for 3P plastics, and heating at a temperature at which non-3P plastics do not melt (e.g., approximately 180°C), the so-called 3P components melt and separate from the non-3P plastics, floating on the solvent, while the non-3P plastics settle apart from the molten 3P components, resulting in gravity separation. Surprisingly, they discovered that by removing the non-3P plastics that did not dissolve in the glycol-based solvent and then rapidly cooling them to below 50-100°C using a glycol-based solvent, which is a solvolysis agent of the same nature, the individual plastic components could be successfully separated and recovered without mixing (see Figures 7A-E). On the other hand, when composite plastic waste contains cellulose, metal, or reinforcing fiber as a third component in addition to plastic, instead of using glycols as a solvent for gravity separation in the first step, a ketone- or xylene-based solvent that selectively dissolves 3P plastics but does not dissolve plastics other than 3P plastics is used as the solvent, and after dissolving and separating the 3P plastics, a glycol-based solvent is used for the non-3P plastics, and it has been found that the 3P plastics can be separated into various components based on the difference in melting temperature.In short, it has been found that it is important to first separate the 3P component from composite plastics by gravity separation using a solvent that makes it easy to separate 3P plastics from non-3P plastics, or by selectively dissolving and recovering the 3P component, and then to separate each component, and further to separate it from the third component, cellulose, metal, and reinforcing fiber.

[0006] Based on this knowledge, the present invention has been developed through extensive research. It has been found that the key to this process is to first separate 3P plastics from non-3P plastics in a manner that allows for easy separation from the solvent in step (A), and then recover the solvent. In step (A), the first method is to (1) melt the 3P plastics using a glycol-based solvent that does not dissolve the 3P plastics but solvolyzes the non-3P plastics, and then perform gravity separation at a solvent temperature that does not melt the non-3P plastics. On the other hand, if the non-3P plastics contain a third component, such as metal or reinforcing fiber, in step (2), the 3P plastics are first dissolved and separated using a ketone- or xylene-based solvent that selectively dissolves the 3P plastics but does not dissolve the non-3P plastics, and then the non-3P plastics are separated from the third component, such as metal. On the other hand, in the second step (B), if gravity separation is performed using a glycol-based solvent in the first step (A), it is desirable to (1) not dissolve the plastics but to remove the gravity-separated plastics other than the 3Ps directly from the system and rapidly cool and separate them using a glycol-based solvent of the same nature, but (2) if metals or reinforcing fibers are included, it has been found that it is better to replace the ketone or xylene-based solvent used in the first step with a glycol-based solvent and separate them based on the difference in melting temperature. Therefore, the present invention has found that it is preferable to combine the above (1) or (2) in the first step (A) and (1) or (2) in the second step (B) as follows, depending on the components of the composite plastic waste, whether or not it contains a third component other than plastics, and further depending on the use of the separated plastics.That is, the present invention is a chemical recycling method for separating composite plastic waste containing various plastics into each component, and includes a first step (A) of separating 3P plastic components including polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P plastics. In the first step (A), when separating the 3P plastic components including polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P plastics, (1) a solvent for dissolving 3P plastics is used instead of a solvent for dissolving 3P plastics. The present invention is characterized in that the second step (B) is either (1) removing the non-3P plastics separated in the first step (A) from the glycol-based solvent for solvolysis without melting the non-3P plastics and then rapidly cooling them in the glycol-based solvent, or (2) separating the non-3P plastics by using a glycol-based solvent at a temperature close to the boiling point of the non-3P plastics, i.e., 180°C, based on the difference in melting temperature. Therefore, the present invention is also a chemical recycling method for composite plastic waste, characterized in that, depending on the type of composite plastic waste, the combination of the first step (A) and the second step (B) is selected from the group consisting of a combination of (A)(1) and (B)(1), a combination of (A)(1) and (B)(2), a combination of (A)(2) and (B)(1), and a combination of (A)(2) and (B)(2).Here, 3P plastics refer to polyethylene (PE), polypropylene (PP), and polystyrene (PS). However, if a composite plastic contains PU (polyurethane), when a ketone- or xylene-based solvent is used, the PU will float on the solvent and be separated from the 3P plastics that dissolve in the solvent. The temperature for gravity separation in the first step is approximately 180°C because, if the composite plastic contains PA, the temperature should be below 180°C, at which point PA begins to dissolve. If the composite plastic does not contain PA, the temperature can be between 180°C and 200°C. Furthermore, if a ketone- or xylene-based solvent is used in the first step and a glycol-based solvent is used in the second step, it is necessary to switch the solvents and set the appropriate temperature.

[0007] According to the present invention, 1) the so-called 3P components are separated from the other components of composite plastic waste by gravity separation using glycols, depending on the components of the composite plastic waste, by precipitating the non-3P plastic components without dissolving them. Alternatively, the 3P components are dissolved and separated using a ketone- or xylene-based solvent. This allows for easy separation of the 3P components from the solvent, even if they are recovered together with the solvent, resulting in the recovery of high-purity 3P components. Specifically, when ketone- or xylene-based solvents are used, the 3P components are separated and recovered together with the solvent, and then cooled, allowing the 3P components to precipitate and be easily separated from the solvent. On the other hand, when a glycol-based solvent is used, the solvent can be separated from the 3P components by distillation. Furthermore, when a glycol-based solvent is used in the first step to melt 3P plastics and separate non-3P plastics by gravity separation, 2) the recovered non-3P plastics can be rapidly cooled in the glycol-based solvent in the second step, allowing them to be separated without intermixing. The phenomenon of gravity-separated non-3P plastics being able to be separated by rapid cooling in a glycol-based solvent, a homogeneous solvolysis solvent, without dissolving them in a solvolysis solvent, is rare. Utilizing this phenomenon provides a new method for separating non-3P plastics and for the separate recovery of composite plastic waste. Therefore, using a glycol-based solvent for household plastic waste that is not separately recovered is effective for separating individual plastic components from composite plastic waste. On the other hand, in cases where 3P plastic components, non-3P plastic components, and a third component, such as aluminum pouches, are combined, it is preferable to pre-treat the 3P plastic components using a ketone- or xylene-based solvent, and then separate and recover the various components using a glycol-based solvent. Therefore, in the present invention, combining the first and second steps (A) and (B) depending on the composition of the composite plastic waste not only allows for the separation and recovery of 3P plastics and non-3P plastics, but also allows for the separation and recovery of metals or reinforcing fibers, making it excellent for separating various components from composite plastic waste.

[0008] 1A is a schematic diagram of the configuration of a separate collection device for composite plastic waste (composite plastics such as 3P + plastics other than 3P + metals: for example, aluminum pouches) in a recycling method according to an embodiment of the second aspect of the present invention. FIG. 1B is a flow sheet of the processes performed in FIG. 1A. FIG. 1C is a schematic diagram of the configuration of a separate collection device for separate and collect various plastic components from collected composite plastic waste (3P + plastics other than P) without sorting, in a recycling method according to an embodiment of the first aspect (household waste) of the present invention. FIG. 1D is a flowchart generally showing the first step (separation involving precipitation of 3P materials) in a method for separate and collect composite plastic waste according to an embodiment of the present invention. FIG. 1E is a flowchart generally showing the second step (separation without precipitation of materials other than 3P) in a method for separate and collect composite plastic waste according to an embodiment of the present invention. FIG. 1F is a flowchart generally showing the step (bleaching of materials) in a method for separate and collect composite plastic waste according to an embodiment of the present invention. FIG. 1G is a schematic diagram showing the configuration of a clothing bleaching device for separate and collect composite plastic waste. FIG. 5A is an explanatory diagram showing a clothing bleaching method performed in the clothing bleaching device of FIG. 5A. FIG. 5C is a schematic diagram of the configuration for separate and collect when the composite plastic waste is diapers. This photograph shows the modification state of a PA (nylon) product when gravity-separated in a glycol-based solvent at a target temperature of 180°C, specifically 190-200°C in this case, in the second step, and then introduced into a glycol-based solvent at room temperature and quenched. This photograph shows the modification state of an acrylic product when gravity-separated in a glycol-based solvent at a target temperature of 180°C, specifically 190-200°C in this case, in the second step, and then introduced into a glycol-based solvent at room temperature and quenched. This photograph shows the modification state of a PET product when gravity-separated in a glycol-based solvent at a target temperature of 180°C, specifically 190-200°C in this case, in the second step, and then introduced into a glycol-based solvent at room temperature and quenched. This photograph shows the modification state of an ABS product when gravity-separated in a glycol-based solvent at a target temperature of 180°C, specifically 190-200°C in this case, in the second step, and then introduced into a glycol-based solvent at room temperature and quenched. This is a photograph showing the state of modification when, in the second step, the PVC product is gravity-separated in a glycol-based solvent at a temperature of approximately 180°C, specifically 190 to 200°C, and then placed in a glycol-based solvent at room temperature and rapidly cooled.

[0009] An embodiment of the present invention will be described below. First, composite plastic waste can be broadly divided into three types of components. The first type is the so-called 3P plastics: polyethylene (PE), polypropylene (PP), and polystyrene (PS). The second type includes plastics other than the 3P type, such as polyurethane (PU), nylon (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and ABS (ABS resin). The third type includes cellulose components, metal components, glass fibers, and carbon fibers. Therefore, composite plastic waste consisting of the first and second components is collected as household plastic waste, while the second type consisting of the first, second, and third components is represented by aluminum pouches. The second type also includes synthetic fibers containing cellulose, such as those found in clothing, instead of metals.

[0010] The present invention provides a chemical recycling method for separating composite plastic waste containing various plastics into its components, which comprises a first step (A) of separating a first component, a 3P plastic component including polyethylene (PE), polypropylene (PP) and polystyrene (PS), from a second component, a plastic component other than the 3P plastics, and a second step (B) of separating and recovering the second component, the plastics other than the 3P plastics, into their respective plastic components, and the first step (A) comprises: (1) using a solvent for solvolysis of the plastics other than the 3P plastics, which is not a solvent for dissolving the 3P plastics, (2) a process in which a ketone-based or xylene-based solvent is used as a solvent for dissolving 3P plastics but not for dissolving plastics other than 3P plastics, and the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent to separate them from the plastics other than 3P plastics, in which the second step (B) is (1) a solvent for solvolysis of the remaining plastics other than 3P plastics, and the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the second step (B) is (1) a solvent for solvolysis of the remaining plastics other than 3P plastics, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent ... 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent, in which the (2) a process in which the remaining plastics other than the 3P type are separated by using a glycol-based solvent at a temperature close to the boiling point of 180 to 280°C using a glycol-based solvent based on the difference in melting temperature, and the process is comprised of a combination of (A)(1) and (B)(1), a combination of (A)(1) and (B)(2), a combination of (A)(2) and (B)(1), and a combination of (A)(2) and (B)(2) depending on the type of composite plastic waste. In the following embodiment, a second embodiment for separating aluminum pouches using a combination of (2) of the first step (A) and (2) of the second step (B) will be described, and a first embodiment for separating household plastic waste using a combination of (1) of the first step (A) and (1) of the second step (B) will be described. However, a person skilled in the art can easily implement each combination for composite plastic waste by adopting a combination of (1) of the first step (A) and (2) of the second step (B) and a combination of (2) of the first step (A) and (1) of the second step (B) in addition to the above combinations.

[0011] Embodiment 1 (Method for treating composite plastic waste (aluminum pouch) containing 3P plastic components + plastic components other than 3P + metal as a third component: Second aspect) When treating aluminum pouches as a representative example of composite plastic waste of the second aspect, it is desirable to treat them in the following steps. That is, the method includes a first step (A) of separating 3P plastic components containing polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P, and a second step (B) of separating and recovering plastics other than 3P into each plastic component, and in the first step (A), when separating 3P plastic components containing polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P, the method includes: (2) separating 3P plastics A chemical recycling method for composite plastic waste is adopted, which is a combination of (2) of the first step (A) and (2) of the second step (B), in which a ketone-based or xylene-based solvent is used as a dissolving solvent but is not a solvent for dissolving plastics other than 3P, and the 3P plastics are dissolved at a dissolving temperature below the boiling point of the solvent to separate them from the plastics other than 3P, and then in the second step (B) (2), the remaining plastics other than 3P are subjected to solvolysis and separation using a glycol-based solvent at a temperature close to the boiling point of 180 to 280°C.

[0012] 1A shows a second embodiment of an apparatus 10 for separating and recovering composite plastic waste, which is capable of decolorizing discolored resins and the like using a process similar to that used for material separation. When decolorizing, the apparatus 10 can be understood as a decolorizing apparatus for performing a decolorizing method that includes steps similar to those of the material separation method described above. The apparatus 10 for separating and recovering composite plastic waste according to this embodiment includes a dissolving tank 12, a first filtration tank 14, a second filtration tank 16, a third filtration tank 18, a first solid-phase polymerization evaporator 20, and a second solid-phase polymerization evaporator 22. The apparatus 10 for separating and recovering composite plastic waste also includes a first separation solvent receiving tank 24 and a second separation solvent receiving tank 26.

[0013] The dissolution tank 12 is equipped with a heater 28, an agitator 30, a basket 31, etc. The heater 28 has the ability to use a burner or the like to raise the temperature of the separation solvent introduced into the dissolution tank 12 and the materials separated by the separation solvent to the melting point (e.g., about 280°C) of the material (target material) for various regeneration purposes (separation or decolorization purposes).

[0014] The agitator 30, the reference number of which is omitted, transmits the rotational force of a motor serving as a drive source to the agitator blades, causing the agitator blades to rotate and agitate the solvent in the dissolution tank 12. The "solvent" referred to here is (1) a glycol-based solvent that is not a solvent for dissolving 3P plastics but is a solvent for solvolysis of plastics other than 3P plastics, or (2) a ketone-based or xylene-based solvent that is a solvent for dissolving 3P plastics but is not a solvent for dissolving plastics other than 3P. The basket 31 has many meshes and functions as a filter to trap solids (solid matter) in the solvent within the dissolution tank 12.

[0015] Waste (raw waste material) and a solvent, which will be described later, are introduced into the dissolution tank 12. Reference numeral 32 in Fig. 1 denotes a flexible container bag containing the waste. The waste is released from the flexible container bag 32 and introduced into the dissolution tank 12.

[0016] The waste material used here is an aluminum pouch, which is a composite plastic made of 3P plastic, plastic other than 3P, and metal aluminum.

[0017] Aluminum pouches are generally made of aluminum, PE, PP, nylon, PET, etc. When aluminum pouches are separated, the raw material aluminum pouches are introduced into a dissolution tank 12 (step (S) 11 in FIG. 2). As described above, the separation solvent introduced into the dissolution tank 12 (S11 in FIG. 2) during separation of the aluminum pouches is a ketone solvent, cyclohexanone.

[0018] When aluminum pouches are separated, the separation process is carried out in two stages, although this depends on the type of material with a high yield. First, a ketone-based separation solvent is used. Separation of the aluminum pouches in the dissolution tank 12 occurs at temperatures ranging from room temperature (e.g., 25°C; the same applies below) to approximately 155°C. The stirring time is, for example, approximately 50 to 80 minutes, and the pressure is normal (atmospheric) pressure. CHN is used as the ketone-based separation solvent.

[0019] Next, a glycol-based separation solvent is used. Separation of the remaining aluminum pouches in the dissolution tank 12 occurs in a temperature range of approximately 155 to 280°C. The stirring time at this time is, for example, approximately 30 to 40 minutes, and the pressure is normal pressure (atmospheric pressure). As the glycol-based separation solvent, one or a mixture of two or more of EG (ethylene glycol), DEG (diethylene glycol), and TEG (triethylene glycol) is used.

[0020] Ketone-based separation solvents and glycol-based separation solvents are generally not mixed and are used separately. This is because they have different boiling points. However, in the case of EG (ethylene glycol) and CHN, if the boiling point difference is about 30°C (boiling point of EG - boiling point of CHN = 186°C - 156°C = 30°C), the liquid obtained by mixing the two can be used as a mixed separation solvent. Even in this case, EG is inexpensive, so no excessive costs are incurred. Furthermore, unused new (fresh) or recycled separation solvents can be used. Reusing separation solvents will be discussed later.

[0021] The aluminum pouches, which are waste, are separated in a separation solvent and stirred by a stirrer 30 while being heated by a heater 28 (S12 in FIG. 2). Dissolution of the contents progresses in the dissolution tank 12. Heating in the dissolution tank 12 is performed while controlling the melting conditions of temperature and time. The temperature and time are controlled according to the physical properties (melting point, etc.) of the target material. The temperature and time can be controlled manually or automatically using a computer device, as described below.

[0022] The remaining undissolved solids (solid matter) are discharged to the outside from a solid discharge port 29 provided in the dissolution tank 12 as shown by arrow A. In the case of separating aluminum pouches, the discharged solids include aluminum and the like. In the case of separating wire harnesses or plastic metals (product name), the discharged solids include metals such as copper. In the case of separating mixed cotton, the discharged solids include fibers.

[0023] More specifically, solids (solid material) are accumulated in a basket 31 installed inside the dissolution tank 12. The solvent leaks out through holes in the basket 31. The accumulated solids (solid material) are discharged from a solid discharge port 29 provided on the side of the dissolution tank 12 as shown by arrow A, and transferred to a centrifuge 33.

[0024] The solids are deliquified and washed in the centrifuge 33. The solids washed in the centrifuge 33 are then transferred to the dryer 35, where they are dried.

[0025] The transfer of the solids (solid materials) from the dissolution tank 12 to the centrifuge 33 and from the centrifuge 33 to the dryer 35 can be performed manually, but may also be performed automatically using a handling device (not shown) controlled by a computer.

[0026] After dissolution at a temperature and time appropriate for the physical properties of the target material, different treatments are performed depending on the regeneration mode, which includes a separation mode that includes precipitation of the target material (hereinafter referred to as the "first regeneration mode"), a separation mode that does not include precipitation of the target material (hereinafter referred to as the "second regeneration mode"), and a decolorization mode that combines the use of precipitation and the use of no precipitation of the target material (hereinafter referred to as the "third regeneration mode").

[0027] These first to third recycling modes are used depending on the type of waste, the recycling mode, etc. The first recycling mode is outlined in Figure 2, the second recycling mode is outlined in Figure 3, and the third recycling mode is outlined in Figure 4.

[0028] In the first regeneration mode, which is a separation mode that includes precipitation of the target material, the temperature of the solvent is lowered by a predetermined amount (e.g., about 30 to 50°C). The lowering of the solvent temperature causes the target material, which has been melted in the solvent, to precipitate. For example, in the case of PE, after melting at a temperature equal to or higher than the melting point of PE, the temperature of the solvent is lowered by a predetermined amount (S13 in Figure 2), and the target material is precipitated (S14 in Figure 2).

[0029] The dissolution tank 12 is connected to a first filtration tank 14, a second filtration tank 16, and a third filtration tank 18 via piping components such as a valve device 34. The filtration tanks 14, 16, and 18 are connected in parallel to one another. Inlet-side valve devices 36, 38, and 40 are installed before the inlets of the filtration tanks 14, 16, and 18. By opening the valve device 34 that opens and closes the outlet of the dissolution tank 12 and selectively opening the inlet-side valve devices 36, 38, and 40 of the filtration tanks 14, 16, and 18, the solvent containing the precipitate from the dissolution tank 12 is introduced into the corresponding filtration tank 14, 16, and 18.

[0030] When separating aluminum pouches, for example, with respect to 3P-type PE (and PP), regeneration is performed in the first regeneration mode, which is a separation mode accompanied by precipitation of the material. In the first regeneration mode, as shown in Figure 2, a temperature-lowering step (S13) is followed by a step of precipitating the target material (S14), and the solvent containing the precipitate is introduced into the corresponding filtration tanks 14, 16, and 18.

[0031] In contrast, in the second regeneration mode, which is a separation mode that does not involve precipitation of the target material, the temperature-lowering step (S13 in FIG. 2) is omitted, and the solvent is transferred (constant temperature transfer, S23 in FIG. 3) and introduced into the corresponding filtration tanks 14, 16, and 18 (S23 and S24 in FIG. 3). The separated solvent is then evaporated and recovered (S25). When separating aluminum pouches, for example, nylon, PET, and aluminum, are regenerated using this second regeneration mode.

[0032] The third regeneration mode (FIG. 4) is used when decolorizing the target material. The third regeneration mode may or may not involve precipitation of the target material. In the third regeneration mode, when no precipitation of the target material occurs, the temperature-lowering step (S13 in FIG. 2) is omitted, and the solvent is transferred at a constant temperature (S33 in FIG. 4), as in the second regeneration mode (FIG. 3). Then, in S34, the determination is made that "precipitation has occurred," and the separation solvent is evaporated to separate the melt (S35), and a decolorizing agent (methanol, CHN, TEG) is added to each of the melts (S36).

[0033] On the other hand, in the third regeneration mode, if precipitation of a material occurs, the temperature-lowering step (S13 in FIG. 2) is performed (S33 in FIG. 4), as in the first regeneration mode (FIG. 2). Here, S33 in FIG. 4 indicates that either a constant-temperature solvent transfer step or a solvent temperature-lowering step is performed. Thereafter, the result in S34 becomes "no precipitation," and the subsequent steps are performed.

[0034] In all of the first to third regeneration modes, the filter tanks 14, 16, and 18 are used depending on the target material. When separating aluminum pouches, separation is performed in the first regeneration mode, and the first filter tank 14 is used to recover PE or PP. The second filter tank 16 and the third filter tank 18 are used to recover nylon or PET.

[0035] In the example of FIG. 1A , when PE reaches its melting point (approximately 130 to 140° C.) and melts, and then undergoes a temperature-lowering step (S13 in FIG. 2 ) to precipitate the target material, for example, the inlet valve device 36 of the first filtration tank 14 is opened, and PE is introduced into the first filtration tank 14.

[0036] Furthermore, even when the PP reaches its melting point (approximately 155°C) and melts, and then undergoes a temperature-lowering process (S13 in Figure 2) to precipitate, the inlet valve device 36 of the first filtration tank 14 is opened, and the PP is introduced into the first filtration tank 14.

[0037] In a situation where nylon melts after reaching its melting point (approximately 190°C) and then precipitates through the temperature-lowering step (S13 in Fig. 2), for example, the inlet valve device 38 of the second filtration tank 16 is opened, and nylon is introduced into the second filtration tank 16. This is inconsistent with the flow in Fig. 1B.

[0038] When the PET reaches its melting point (approximately 230°C) and melts, and then undergoes a temperature-lowering process (S13 in Figure 2) to precipitate, for example, the inlet valve device 40 of the third filtration tank 18 is opened, and the PET is introduced into the third filtration tank 18.

[0039] The use of each of the filter tanks 14, 16, 18 is not limited to this embodiment, and can be determined in various ways.

[0040] A filter (shown by a broken line) is installed in each of the filtration tanks 14, 16, and 18, and a precipitate is extracted from the introduced solvent (S15 in FIG. 2). The extracted precipitate is taken out of each of the filtration tanks 14, 16, and 18, as shown by arrows B1 to B3, and introduced into the first solid-state polymerization evaporator 20 or the second solid-state polymerization evaporator 22.

[0041] The first solid-state polymerization evaporator 20 is connected to the first filtration tank 14, and the second solid-state polymerization evaporator 22 is connected to the second filtration tank 16 and the third filtration tank 18. In the example of Figure 1A, the first solid-state polymerization evaporator 20 is used for the polymerization of PE or PP, and the second solid-state polymerization evaporator 22 is used for the polymerization of nylon or PET.

[0042] The first solid-state polymerization evaporator 20 and the second solid-state polymerization evaporator 22 are provided with agitators 42, 44. Although the reference numerals are omitted, the agitators 42, 44 transmit the rotational force of a motor serving as a drive source to the agitator blades to rotate the agitator blades.

[0043] Target material powder receiving tanks 52, 54 are connected via valve devices 48, 50 to the outlets at the bottom of the first solid-state polymerization evaporator 20 and the second solid-state polymerization evaporator 22. Powder (pellets) of the target material polymerized in the first solid-state polymerization evaporator 20 and the second solid-state polymerization evaporator 22 are introduced into the target material powder receiving tanks 52, 54. The target material is then removed from the target material powder receiving tanks 52, 54 as needed.

[0044] The target material in the target material powder receiving tanks 52, 54 is resin powder obtained by vaporizing the separated solvent liquid using a first vacuum system 53 and a second vacuum system 55. The first vacuum system 53 and the second vacuum system 55 are connected to the upper outlets of the first solid-phase polymerization evaporator 20 and the second solid-phase polymerization evaporator 22. Each vacuum system 53, 55 is composed of a vacuum container, a vacuum pump, etc., although detailed illustration is omitted.

[0045] Each vacuum system 53, 55 sucks the components of the separation solvent liquid mixed with the precipitate (in the first regeneration mode) introduced into the corresponding solid-phase polymerization evaporator 20, 22 and evaporates them by vacuum distillation (S18 in FIG. 2). Furthermore, each vacuum system 53, 55 discharges the obtained components (components of the separation solvent) toward the first separation solvent receiving tank 24 or the second separation solvent receiving tank 26 by the action of pumps 56, 58.

[0046] The first vacuum system 53 is connected to the first separation solvent receiving tank 24, and the second vacuum system 55 is connected to the second separation solvent receiving tank 26. In the example of Figure 1, CHN (the solvent may be composed of a mixed solvent of a ketone-based solvent cyclohexanone CHN and methyl isobutyl ketone, but will be referred to as CHN hereinafter for convenience) is discharged from the first vacuum system 53 to the first separation solvent receiving tank 24, and a glycol-based solvent (which may be composed of a mixed solvent of one or more of EG, DEG, and TEG, but will be referred to as TEG hereinafter for convenience) is discharged from the second vacuum system 55 to the second separation solvent receiving tank 26.

[0047] Heaters 60, 62 are installed on the piping between the first vacuum system 53 and the first separating solvent receiving tank 24 and on the piping between the second vacuum system 55 and the second separating solvent receiving tank 26. CHN and TEG pumped out by the pumps 56, 58 are heated by the heaters 60, 62 and introduced into the first separating solvent receiving tank 24 and the second separating solvent receiving tank 26.

[0048] The outlets of the above-mentioned filtration tanks 14, 16, and 18 are connected to the first separation solvent receiving tank 24 and the second separation solvent receiving tank 26 via outlet-side valve devices 64, 66, and 68. In this embodiment, the first filtration tank 14 joins the piping between the first vacuum system 53 and the first separation solvent receiving tank 24, and the second filtration tank 16 and the third filtration tank 18 join the piping between the second vacuum system 55 and the second separation solvent receiving tank 26.

[0049] The components (filtrate) filtered in the first filtration tank 14 are delivered by a pump 70, heated by a heater 60 along the way, and introduced into the first separation solvent receiving tank 24. The components filtered in the second filtration tank 16 and the third filtration tank 18 are delivered by a pump 72, heated by a heater 62 along the way, and introduced into the second separation solvent receiving tank 26.

[0050] CHN is supplied from the first separation solvent receiving tank 24 to the dissolution tank 12, and TEG is supplied from the second separation solvent receiving tank 26 to the dissolution tank 12. In the dissolution tank 12, the CHN from the first separation solvent receiving tank 24 and the TEG from the second separation solvent receiving tank 26 are reused as separation solvents for dissolving the waste.

[0051] The solidified precipitate is polymerized in the first solid-state polymerization evaporator 20 or the second solid-state polymerization evaporator 22 (S16 in FIG. 2 ), and the target material obtained by polymerization is taken out from the first solid-state polymerization evaporator 20 or the second solid-state polymerization evaporator 22 (S17 in FIG. 2 ).

[0052] In the case of separating aluminum pouches, PE or PP is extracted from the first solid-state polymerization evaporator 20, and nylon or PET is extracted from the second solid-state polymerization evaporator 22. The target material extracted from the first solid-state polymerization evaporator 20 or the second solid-state polymerization evaporator 22 is fragmented into pellets (solid powder).

[0053] In this way, in the composite plastic waste sorting and recovery device 10, the waste and separation solvent are put into the dissolution tank 12, and the waste is dissolved under temperature control (dissolution step, S11 and S12 in FIG. 2). The target materials for separation (PE or PP, nylon or PET in the example of FIG. 1) are precipitated from the solvent obtained in the dissolution step, and the target materials are separated by type (part of the separation step, S13 and S14 in FIG. 2).

[0054] The materials are regenerated sequentially for each target material according to their melting points. Furthermore, in the separation process, filter tanks 14, 16, and 18 are used, each for a different type of target material. Multiple filter tanks 14, 16, and 18 are provided, with different types of target materials stored in different filter tanks 14, 16, and 18 (part of the separation process, Fig. 15 in Fig. 2). The separated target materials are polymerized (polymerization process, S16 in Fig. 2) and removed (removal process, S17 in Fig. 2). The separation solvent in the solvent is separated in each filter tank 14, 16, and 18 and recovered in the separation solvent receiving tanks 24 and 26 (recovery process, S18 in Fig. 2).

[0055] In particular, the separation of the aluminum pouch can be explained as follows by applying Figures 2 and 3.

[0056] The "waste" in S11 of Figure 2 is an aluminum pouch (e.g., containing PE, nylon, PET, and aluminum), and the "separation solvent" is CHN. The "precipitation of target material" in S14 of Figure 2 corresponds to the precipitation of PE. The "filtration of solvent" in S15 of Figure 2 corresponds to the filtration of a solvent containing CHN. The "polymerization of target material" in S16 of Figure 2 corresponds to the polymerization of PE.

[0057] The "waste" in S11 of Fig. 3 corresponds to the residue (residue) accumulated in the basket 31 of the dissolution tank 12 (Fig. 1), specifically nylon, PET, and aluminum. The "separation solvent" in this case corresponds to TEG.

[0058] In S25 of Fig. 3, "evaporation of separation solvent" corresponds to evaporation of TEG, and "recovery" corresponds to recovery of nylon, PET, and aluminum. "Recovery" is performed in the order of nylon, PET, and aluminum. "Removal of target material" in S17 of Fig. 3 corresponds to removal of nylon and PET.

[0059] The separation of the aluminum pouch can also be explained as follows based on FIGS. 1A and 1B, 2 and 3.

[0060] The crushed aluminum pouches are all placed in a basket 31 (FIG. 1) (S11 in FIG. 2), and are immersed in CHN in a stirred state while controlling the temperature and time (S12 in FIG. 2). As a result, the PE and PP dissolve, and the PE, PP, and CHN flow out from the holes in the basket 31. When cooled to about 50°C (S13 in FIG. 2), the PE and PP precipitate (S14 in FIG. 2) and are filtered (S15 in FIG. 2).

[0061] The filtrate is reheated and transferred to the dissolution tank 12. The PE and PP containing CHN are powdered under vacuum in the first solid-phase polymerization evaporation vessel 20 (S16 in FIG. 2).

[0062] Nylon, PET, and aluminum remain in the basket 31 of the dissolution tank 12. The separation solvent is replaced with TEG (S11 in FIG. 3), and the liquid temperature is maintained at approximately 160-180°C for 30 minutes (S12 in FIG. 3). The nylon dissolves and flows out through the holes in the basket 31 (S23 in FIG. 3). Since nylon does not precipitate in the TEG (S24 in FIG. 3), the TEG is evaporated and recovered (S25 in FIG. 3). At this time, filter paper with a finer mesh than the holes in the basket 31 is placed in the container.

[0063] After that, PET and aluminum remain in the basket 31 of the dissolution tank 12. TEG is used as the separation solvent (S11 in FIG. 3), and the liquid temperature is set to 200-280°C and maintained for approximately 15 minutes (S12 in FIG. 3). The PET melts and flows out from the holes in the basket 31 (S23 in FIG. 3). Since the PET does not precipitate in the TEG (S24 in FIG. 3), the TEG is evaporated and recovered (S25 in FIG. 3). At this time, filter paper with a finer mesh than the holes in the basket 31 is also placed.

[0064] Thereafter, the aluminum remains in the basket and is discharged from the melting tank 12 to the outside of the system (S17).

[0065] In the explanation of aluminum pouch separation so far, the main purpose has been to separate PE and PP. CHN is selected as the separation solvent for PE and PP, while TEG is selected for nylon and PET. CHN turns PE and PP into foamed resin, which makes separation by filtration very effective, and it is also possible to bleach PE and PP to white.

[0066] Furthermore, with regard to the deposition of the target material, the deposition rate increases as the temperature increases.

[0067] Like aluminum pouches, diapers (also known as disposable diapers) are another waste material that can be classified as mixed film. For both aluminum pouches and diapers, the main material to be separated is often polyolefin (PE, PP). For this reason, CHN and TEG are used as separation solvents for both aluminum pouches and diapers, and the order of use is CHN first, then TEG, as explained above.

[0068] In the above example, the yields of PE and PP are high. In the case of aluminum pouches, the yields of PE and PP are about 85 wt %, and in the case of diapers, the yields of PE and PP are about 90 wt %. In the case of aluminum pouches, the remaining materials are nylon, PET, and aluminum, which are processed at different times relative to the PE and PP using the second solid-state polymerization evaporator 22.

[0069] The above explanation has been given mainly on the separation of aluminum pouches as an example. This can be summarized as the flow sheet shown in Figure 1B, but separation can also be performed on other mixed films in a similar manner. For example, in the case of the above-mentioned tent, PET and PE are generally used, and by adjusting the temperature of the dissolution tank 12, PET can be removed from the first solid-state polymerization evaporator 20 and PE can be removed from the second solid-state polymerization evaporator 22.

[0070] In addition, materials can be separated from waste materials other than mixed films in the same way. Table 1 shows the conditions for the separate collection of composite plastic waste related to various types of waste. By controlling the temperature and time in the dissolution tank 12 under the conditions shown in Table 1, it is possible to separate the target materials.

[0071]

[0072] For any of the wastes shown in Table 1, the amount of separation solvent replenished (added) is sequentially added, and it is appropriate that the amount is 5 to 10 wt % of the weight of the waste.

[0073] Here, the separation solvent can be selected taking into consideration various factors, such as the characteristics for separating the target material, the relationship between the boiling point of the separation solvent and the melting point of the target material (boiling point of the separation solvent < melting point of the target material), the price of the separation solvent, etc. For example, glycol-based separation solvents include TEG, DEG (diethylene glycol), ethylene glycol, etc. The boiling points and prices increase in the order of ethylene glycol, DEG, and TEG. The separation solvent can be selected taking into consideration the melting point of the target material, the boiling point and price of the separation solvent used in combination, etc.

[0074] Glycol-based separation solvents will be described in detail. The number of carbon atoms in glycol-based separation solvents is preferably 2 to 40, more preferably 2 to 20, and even more preferably 2 to 12. Glycol-based separation solvents may be water-soluble or water-insoluble. Examples of glycol-based separation solvents include alkylene glycols. Examples of alkylene glycols include monoalkylene glycol, dialkylene glycol, trialkylene glycol, tetraalkylene glycol, pentaalkylene glycol, hexaalkylene glycol, and polyalkylene glycol. The alkylene group contained in the alkylene glycol may be linear or branched, preferably has 2 to 8 carbon atoms, and when multiple alkylene groups are present, the multiple alkylene groups may be the same or different. Examples of glycol-based separation solvents include ethylene glycol, propylene glycol, DEG (diethylene glycol), dipropylene glycol, and TEG (tetraethylene glycol). Glycol-based separation solvents may be used alone or in combination. When a glycol-based separating solvent is used as a separating solvent mixed with other types of solvents (mixed separating solvent), the content of the glycol-based separating solvent is, for example, 20 wt % or more and less than 80 wt % relative to the total mass of the mixed separating solvent. A separating solvent consisting essentially of a glycol-based separating solvent may also be used, in which case the content of the glycol-based solvent relative to the total mass of the separating solvent is 80 to 100 wt % (preferably 90 to 100 wt %, more preferably 95 to 100 wt %, and even more preferably 99 to 100 wt %).

[0075] Ketone-based separation solvents will be described in detail. Ketone-based separation solvents are organic solvents having a ketone structure, and examples thereof include chain ketones, cyclic ketones, and aromatic ketones. A cyclic ketone refers to a ketone that includes a carbonyl group as part of the cyclic structure. An aromatic ketone refers to a ketone in which a carbonyl group is bonded to an aromatic ring. The number of carbon atoms in the ketone-based separation solvent is preferably 3 to 30, more preferably 4 to 15, and even more preferably 5 to 8. The ketone-based separation solvent may be water-soluble or water-insoluble. Examples of ketone-based separation solvents include CHN (cyclohexanone), MIBK (methyl isobutyl ketone), 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone (methyl amyl ketone), 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, 2,5-dimethyl-4-hexanone, diisobutyl ketone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate, with cyclohexanone and methyl isobutyl ketone being particularly preferred. Ketone-based separation solvents may be used alone or in combination. When a ketone-based separating solvent is used as a separating solvent mixed with other types of solvents (mixed separating solvent), the content of the ketone-based separating solvent may be, for example, 20 wt % or more and less than 80 wt % based on the total mass of the mixed separating solvent. A separating solvent consisting essentially of a ketone-based separating solvent may also be used, in which case the content of the ketone-based separating solvent is 80 to 100 wt % (preferably 90 to 100 wt %, more preferably 95 to 100 wt %, and even more preferably 99 to 100 wt %) based on the total mass of the separating solvent.

[0076] As the separation solvent, it is preferable to use an aromatic hydrocarbon-based, particularly a xylene-based, separation solvent. An aromatic hydrocarbon-based separation solvent is an organic solvent composed of a hydrocarbon having an aromatic ring. The number of carbon atoms in the aromatic hydrocarbon-based separation solvent is preferably 6 to 30, more preferably 6 to 15, and even more preferably 6 to 8. Examples include benzene, alkylbenzene, alkylnaphthalene, alkylbiphenyl, and alkyldiphenylalkane, with xylene (m-xylene, p-xylene, o-xylene, or a mixture of two or more of these) being particularly desirable. Xylene-based separation solvents may be used alone or in combination. When used as a separation solvent mixed with other solvents (mixed separation solvent), the content of the xylene-based separation solvent is, for example, 20 wt % or more but less than 80% of the total mass of the mixed separation solvent. A separating solvent consisting essentially of a xylene-based separating solvent may be used. In this case, the content of the aromatic hydrocarbon-based separating solvent relative to the total mass of the separating solvent is 80 to 100 wt % (preferably 90 to 100 wt %, more preferably 95 to 100 wt %, and even more preferably 99 to 100 wt %).

[0077] In addition, some separation solvents, such as CHN, have a dechlorination function. Therefore, it is possible to select a separation solvent that has a dechlorination function or a separation solvent with a relatively high dechlorination function.

[0078] Furthermore, in addition to CHN, MIBK (methyl isobutyl ketone) can be cited as a preferred ketone-based separation solvent. Comparing CHN and MIBK, CHN has a higher boiling point and is less harmful to the human body. For this reason, it is possible to select CHN as the separation solvent.

[0079] The composite plastic waste sorting and recovery device 10 and the composite plastic waste sorting and recovery method performed by the composite plastic waste sorting and recovery device 10 as described above make it possible to separate the materials contained in the waste as individually as possible. It is also possible to decolorize discolored resin and mixed cotton. This further promotes resource reuse and contributes to environmental protection. The mixed cotton also undergoes a two-stage separation process to separate the materials and decolorize them, just like the aluminum pouches.

[0080] Furthermore, according to the composite plastic waste sorting and recovery device 10 and the composite plastic waste sorting and recovery method performed by the composite plastic waste sorting and recovery device 10, all of the materials shown in Table 1 are of a recyclable quality after separation and decolorization.

[0081] Furthermore, according to the apparatus 10 for separating and recovering composite plastic waste of this embodiment, it is possible to separate individual target materials with a simple configuration.

[0082] Furthermore, the amount of the replenishing solvent to be added is preferably 5 to 10 wt %, and it is preferable to separate the target materials individually using a small amount of the separation solvent.

[0083] It should be noted that the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereby. In other words, the present invention can be carried out in various forms without departing from the gist or main features thereof.

[0084] For example, in the apparatus 10 for separating and recovering composite plastic waste shown in FIG. 1A and the method for separating and recovering composite plastic waste performed by the apparatus 10 for separating and recovering composite plastic waste, the management of conditions such as the temperature and time of the dissolution tank 12, the opening and closing of each valve device, and the removal of precipitates from each filtration tank 14, 16, 18 are performed manually, but these may be automated to separate the target materials by continuous processing.

[0085] In this case, for example, a temperature sensor, a pressure sensor, etc. are installed in the dissolution tank 12, and the computer equipment monitors the outputs of these sensors and determines whether the conditions for opening and closing the valve devices are met. The various valve devices are opened and closed according to the judgment results and automatic control of the computer equipment, and the delivery of the solvent is managed. The removal of the precipitate can also be performed using a transfer device, etc., controlled by the computer equipment. Such automation makes it possible to separate a larger number of materials while saving labor.

[0086] Next, we will explain the recycling of clothing. We have explained that colored mixed cotton can contain clothing, etc., and that in colored mixed cotton, etc., the dye and material are separated and the material is decolorized. Figure 5A shows a clothing bleaching device 100 as an example of a device for separating and recovering composite plastic waste. The clothing bleaching device 100 is configured by combining multiple devices. The clothing bleaching device 100 can also be understood as an example of a system for separating and recovering composite plastic waste (clothing bleaching system).

[0087] Component recovery method for embodiment 2 (clothing waste containing 3P plastics and plastics other than 3P in addition to cellulose fibers) The clothing bleaching device 100 is capable of separating materials (material separation). Therefore, the clothing bleaching device 100 can be understood as a material separation device that performs a specific material separation method. Furthermore, the clothing bleaching method performed by the clothing bleaching device 100 is one aspect of a method for separating and recovering composite plastic waste.

[0088] The clothing bleaching device 100 according to this embodiment includes a mixing tank 102, a heater-equipped receiving tank 104, a circulation pump 106, an evaporation tank 108, a vacuum receiving tank 110, a vacuum pump 112, a condenser 114, and a dye recovery tank 116. The clothing bleaching device 100 further includes a liquid feed pump 118, a centrifugal deliquor 120, and the like.

[0089] Of these, a basket (cage) 124 is transferred to the mixing tank 102 via a transfer unit 122. The basket 124 has mesh-like walls and a bottom, and is suspended from the transfer unit 122. The basket 124, with clothes (not shown) stored inside, is moved by the transfer unit 122 to the mixing tank 102 or the centrifugal deliquor 120. Furthermore, the basket 124 is lowered by the transfer unit 122 at the position of the mixing tank 102 or the centrifugal deliquor 120.

[0090] In Fig. 5A, the state in which the basket 124 containing the clothes (not shown) has been lowered into the mixing tank 102 is shown by a dashed line. Furthermore, in Fig. 5, the state in which the basket 124 has been transferred to the upper part of the centrifugal deliquor 120 is shown imaginarily by a two-dot chain line.

[0091] The mixing tank 102 is connected via piping (reference numeral omitted) to a heater-equipped receiving tank 104. The heater-equipped receiving tank 104 contains a mixed fluid (separation solvent) 126 of ethylene glycol (EG) and a dye (corresponding to step (S)41 in FIG. 6 ), and the heated fluid in the heater-equipped receiving tank 104 is sent to the mixing tank 102 via a circulation pump 106 (S42).

[0092] A valve device 128 is provided between the mixing tank 102 and the heater-equipped receiving tank 104. By opening the valve device 128, the separation solvent (not shown) in the mixing tank 102 is returned to the heater-equipped receiving tank 104 (corresponding to the flow from S43 to S41) and reused (first reuse).

[0093] The mixing tank 102 is equipped with a heater (an electric heater in this case) 130, and the separation solvent in the mixing tank 102 is heated by the heater 130. The mixing tank 102 is covered (surrounded) by a heat insulating material 132, which keeps the mixing tank 102 (and the separation solvent) warm.

[0094] The heater-equipped receiving tank 104 is equipped with a heater 134, and the separation solvent 126 in the heater-equipped receiving tank 104 is heated by the heater 134. The heater-equipped receiving tank 104 is covered (surrounded) by a heat insulating material 136, which keeps the separation solvent 126 warm.

[0095] In the mixing tank 102, the clothes in the basket 124 are mixed with the bleaching agent and decolorized by a liquid circulation method (by convection) (S43, first decolorization). In other words, the clothes are decolorized by circulating the separation solvent rather than by stirring. The operating conditions of the mixing tank 102 are atmospheric pressure, a temperature of 150 to 190°C, and a retention time of the clothes of 15 to 60 minutes. When the treatment in the mixing tank 102 is completed, the basket 124 is lifted by the transfer section 122 and transferred to the centrifugal deliquor 120. The clothes in the basket 124 are transferred to the centrifugal deliquor 120 with the separation solvent soaked in (adhering to) them.

[0096] In the centrifugal deliquor 120, the decolorized clothes (decolorized clothes) and the separation solvent adhering to the decolorized clothes are centrifuged (S44). The separation solvent removed by centrifugal force is discharged and stored in the separation solvent receiving tank 138. The separation solvent (not shown) in the separation solvent receiving tank 138 is sent to the heater-equipped receiving tank 104 and returned to the heater-equipped receiving tank 104 for reuse (second reuse) (S45).

[0097] Next, wash water is supplied to the centrifugal dewatering unit 120 as shown by arrow C1 (S46). In the centrifugal dewatering unit 120, EG adhering to the bleached clothes is removed by centrifugal force using the wash water (S47), and the clothes are bleached (second bleaching). Furthermore, the mixture of EG separated from the bleached clothes and wash water is collected in the mixing tank 140 (S54). The dewatered clothes are removed from the centrifugal dewatering unit 120, dried, and collected. In this way, the clothes are bleached and dewatered multiple times (twice in this case).

[0098] A portion of the separation solvent 126 in the heater-equipped receiving tank 104 is sent to the evaporation tank 108 (S50), where it is heated by the heater 142 while mixed with the dye separated from the clothes. The heated separation solvent evaporates (S51) and is separated (separated) from the dye. The separated dye is collected in the dye collection tank 116 by opening the valve device 144. In this way, the dye itself is collected.

[0099] The separation solvent evaporated in the evaporation tank 108 passes through the condenser 114 (S52) and flows into the vacuum receiving tank 110 (S53). The interior of the vacuum receiving tank 110 is evacuated by a vacuum pump 112, and the separation solvent from the condenser 114 flows into the vacuum receiving tank 110 due to the pressure difference caused by the evacuation. The separation solvent 146 stored in the vacuum receiving tank 110 is sent to the heater-equipped receiving tank 104 via the liquid delivery pump 118 (flow from S53 to S41), and is reused in the heater-equipped receiving tank 104 (third reuse).

[0100] According to the clothing decolorization device 100 (composite plastic waste sorting and recovery device) and clothing decolorization method (composite plastic waste sorting and recovery method) described above, clothing colored with dyes is decolorized multiple times, thereby allowing the clothing to be decolorized as much as possible.

[0101] Furthermore, since the system is equipped with multiple recycling sections (here, a first recycling section including a valve device 128 and piping, a second recycling section including a separation solvent receiving tank 138 and piping, and a third recycling section including an evaporation tank 108, a condenser 114, a vacuum receiving tank 110, and piping), it is possible to recover a high percentage of the separation solvent. In the inventors' experiments, it was possible to recover 98 wt% of the separation solvent. These facts indicate that thorough recycling of the separation solvent is possible.

[0102] Furthermore, since the separated dye is collected in the dye collection tank 116, the dye (the dye itself) can be reused.

[0103] The following inventions can be extracted from the above-described embodiments relating to the recycling of clothing. (1) A method for separating and recovering composite plastic waste, comprising: a first decolorization process (e.g., S41 to S43) in which colored clothing is mixed with a separation solvent supplied from a separation solvent supply unit (e.g., a receiving tank 104 equipped with a heater) in a first decolorization unit (e.g., a mixing tank 102) to decolorize the clothing; a second decolorization process (e.g., S44) in which the separation solvent adhering to the clothing decolorized in the first decolorization process is removed; a first recycling process (e.g., a flow returning from S43 to S41) in which the separation solvent used in the first decolorization process is returned to the separation solvent supply unit for reuse; a second recycling process (e.g., a flow returning from S45 to S41) in which the separation solvent removed in the second decolorization process is returned to the separation solvent supply unit for reuse; and a third recycling process (e.g., a flow returning to S41 via S50 to S53) in which the separation solvent from the separation solvent supply unit is separated from the mixed dye and returned to the separation solvent supply unit for reuse. (2) A separation solvent supply unit (such as a heater-equipped receiving tank 104), a first decolorization unit (such as a mixing tank 102) that mixes colored clothing with the separation solvent supplied from the separation solvent supply unit to perform a first decolorization step (such as S41 to S43), a second decolorization unit (such as a centrifugal deliquor 120) that removes the separation solvent adhering to the clothing decolorized in the first decolorization unit and performs a second decolorization step (such as S44), a first recycling unit (such as a valve device 128 or piping) that returns the separation solvent used in the first decolorization step to the separation solvent supply unit, a second recycling unit (such as a separation solvent receiving tank 138 or piping) that returns the separation solvent removed in the second decolorization step to the separation solvent supply unit, and a second recycling unit (such as a separation solvent receiving tank 138 or piping) that separates the separation solvent from the separation solvent supply unit from the mixed dye and returns it to the separation solvent supply tank. and a third recycling section (evaporation tank 108, condenser 114, vacuum receiving tank 110, piping, etc.) for returning the waste plastics.

[0104] Embodiment 3 (Method for treating composite plastic waste (household plastic waste) containing 3P plastic components and plastic components other than 3P plastics: First aspect) When treating household plastic waste as a representative example of composite plastic waste of the first aspect, it is desirable to treat it in the following steps. That is, the method includes a first step (A) of separating 3P plastic components containing polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P plastics, and a second step (B) of separating and recovering plastics other than 3P plastics into individual plastic components, and in the first step (A), when separating the 3P plastic components containing polyethylene (PE), polypropylene (PP) and polystyrene (PS) from plastic components other than 3P plastics, the first step (A) includes: (1) using a grout that is not a solvent for dissolving 3P plastics but a solvent for solvolysis of plastics other than 3P plastics; The method uses a glycol-based solvent to melt 3P plastics at 200°C or below, preferably at a temperature that does not melt PA, for example, 180°C or below, and floats them on the solvent, while allowing plastics other than 3P to settle, thereby separating them by gravity. The second step (B) is (1) a step in which a glycol-based solvent, which is a solvent for solvolysis of the remaining non-3P plastics, is used, and the non-3P plastics are removed from the system without melting, rapidly cooled, and separated. A chemical recycling method for composite plastic waste is adopted, which consists of a combination of the first step (A) (1) and the second step (B) (1).

[0105] The chemical recycling method described above is implemented using the configuration 200 shown in Figure 1C. Household plastic waste typically contains 3P plastic components (PE, PP, and PS) as well as PVC, PET, ABS, and metal components. (1) In the first step, the 3P plastic components are separated from other plastic components. Because PA is not included in this process, a glycol-based solvent is used as the first solvent for gravity separation, and the heating temperature is set to approximately 200°C. (If PA is included, a temperature of 180°C or less is recommended. That is, the temperature is set to a temperature sufficient to melt and separate the 3P components while not melting the other components.) The solvent composition is selected from one or more of the group consisting of EG, DEG, and TEG. In this case, a DEG:TEG ratio of 50:50 (by weight) is selected, adjusted to a boiling point of 250°C, and heated to 200°C. (The solvent composition determines the boiling point, so the heating temperature for gravity separation is taken into consideration.) (2) 50 liters of the first glycol-based solvent is placed in a 100-liter melting / separation tank 200 and heated (the amount of solvent should be equal to or greater than the amount of household plastic waste being introduced for gravity separation). Household plastic waste in an amount roughly equal to the solvent is introduced from flexible container packs 201 into inlet 220, whereupon the water evaporates and is collected and recovered in agglomerator 202. The specific gravity of this glycol-based solvent is approximately 1.1, while the specific gravity of the 3P components is approximately 0.9. Therefore, the 3P components in the household plastic waste melt in the solvent heated to 190-200°C, and are separated from the non-3P components by stirring, melting and floating on top of the glycol-based solvent. On the other hand, the non-3P plastic components (here, PVC, PET, and ABS) are heavier than the solvent and do not melt at 190-200°C. Therefore, they sink to the bottom of the melting / separation tank 201. (3) The 3P components that melt and float on the first solvent are temporarily collected together with the solvent in a 3P collection tank 203. The molten 3P components are then sent together with the solvent via a screw conveyor 204 to a distillation column 205, where the solvent is distilled. Meanwhile, the 3P components are collected from below 209 and thermally decomposed in a thermal decomposition tank 211 heated by a burner 212.When TEG is used as the solvent, the TEG is heated to 330°C in distillation column 205 to distill it, while the 3P components are sent in a molten state at 320°C to pyrolysis tank 211 and heated to 420°C. Here, the 3P components are distilled and temporarily received in hot oil receiver 213 and sent to seal pot 215 via condenser 214, while they are sent from pyrolysis oil receiver 213 to pyrolysis oil tank 217 via pump 218 and recovered by pump 219. The solvent distilled in pyrolysis oil receiver 213 is recovered and deodorized at 600°C in deodorizing furnace 216. The solvent recovered in 3P recovery tank 203 is sent to separating agent receiver (with heater) 221 by transfer pump 210, and from there circulated to melt separation tank 201 via separating agent transfer pump 222. (4) Plastics other than 3P that settle in the heated solvent in the melting decomposition tank 201 are discharged from the bottom of the decomposition tank 201 without dissolving, rapidly cooled on a conveyor 207, and separated into PVC, PET, ABS, metals, etc. in the heavy liquid receiving tank 208. Specifically, using a heavy liquid (e.g., TEG, DEG, or a mixture thereof) heated to 70°C, the plastics are separated based on their specific gravity into 1) a light weight group of ABS / PA / PU / PVC (here, ABS and PVC), 2) a medium weight group of PET, and 3) a weight group of metals. The group 1) can then be separated by manual sorting. Plastics other than 3P that settle in the TEG heated to 200°C in the melting decomposition tank 201 are removed from the system, placed in a glycol-based solvent at room temperature, and rapidly cooled to 50°C to 100°C or less, allowing them to be separated into each plastic. When nylon (PA) is held in a TEG at 190-200°C for 5 minutes and then placed in a TEG at room temperature, the left-hand rope-shaped PA transforms from the left-hand rope shape to the right-hand shape and settles, as shown in Figure 7A. Similarly, when acrylic resin is held in a TEG at 190-200°C for 5 minutes and then placed in a TEG at room temperature, the acrylic resin body formed into a left-hand frame shape transforms into the right-hand shape and settles, as shown in Figure 7B. Furthermore, when PET resin is held in a TEG at 190-200°C for 5 minutes and then placed in a TEG at room temperature, the PET resin body formed into the left-hand shape transforms into the right-hand shape and settles, as shown in Figure 7C.Furthermore, when ABS resin is held in a TEG at 190-200°C for 5 minutes and then placed in a TEG at room temperature, the PET resin body molded into the left-hand frame shape transforms into the right-hand shape and settles, as shown in Figure 7D. Similarly, when PVC resin is held in a TEG at 190-200°C for 5 minutes and then placed in a TEG at room temperature, the PVC resin body molded into the left-hand frame shape transforms into the right-hand shape and settles, as shown in Figure 7E. While this phenomenon is mysterious, it is hypothesized as follows: In the first step, the glycol-based solvent heated to 190-200°C penetrates the plastics other than the 3P, softening them without dissolving them, causing them to transform and settle. Because the plastics are only softened, not melted, and are covered by the solvent, they are thought to be able to be separated without welding to each other (see Figures 7A-7E). Therefore, in this embodiment, 3P plastics are melted and floated on the glycol-based solvent, while plastics other than 3P are precipitated in the glycol-based solvent for separation. Therefore, if the plastics other than 3P contain PA, the solvent temperature should be set to 180°C or below. If they do not contain PA, the solvent temperature should be set to 190°C to 200°C. This is to achieve specific gravity separation, melting and floating the 3P plastics in the composite plastic waste, while the plastics other than 3P are not melted and are precipitated. (5) In this embodiment, PE, PP, and PS can be recovered as pyrolysis oil without separation, but further separation processing can be performed to separate PE, PP, and PS.

[0106] Embodiment 4 (separate collection of composite plastic waste (disposable diapers) containing 3P plastics containing cellulose as a third component and plastics other than 3P) When disposable diapers are treated as a representative example of composite plastic waste of the third embodiment, it is desirable to treat them in the following steps. That is, the method includes a first step (A) of separating 3P plastic components containing polyethylene (PE), polypropylene (PP), and polystyrene (PS) from plastic components other than 3P, and a second step (B) of separating and collecting plastics other than 3P into each plastic component, and in the first step (A), when separating the 3P plastic components containing polyethylene (PE), polypropylene (PP), and polystyrene (PS) from plastic components other than 3P, (2) a ketone-based or xylene-based solvent is used as a solvent for dissolving 3P plastics, but is not a solvent for dissolving plastics other than 3P. This process involves dissolving 3P plastics while melting and floating non-3P plastics on the solvent, separating the two. If the non-3P plastics melt in the first process, the third component is collected in a basket, eliminating the need for the second process (B). However, if the non-3P plastics do not melt in the first process, a glycol-based solvent is used in the second process (2), which is a solvent for solvolysis of non-3P plastics. The non-3P plastics are melted and separated from the third component. This chemical recycling method for composite plastic waste combines the first process (A) (2) and the second process (B) (2). Here, when disposable diapers are composed of the 3P components (PE and PP), the non-3P component (PU), and the third component (cellulose pulp), the configuration shown in Figure 6 is used. The ketone solvent cyclohexanone (CHN) is used as the separation solvent. Raw material disposable diapers are placed in a dissolution and separation tank 301, where the 3P components of the disposable diapers, PE and PP, are dissolved, while the PU, a component other than the 3P, is not dissolved but is melted onto the solvent. In the dissolution and separation tank 301, the solvent is heated to 150°C under normal pressure for 30 minutes using a heater 302 and stirred with an agitator 303, whereupon the 3P components, PE and PP, dissolve in the solvent, while the PU melts and floats on the solvent. The pulp is collected in a basket 303, and both are recovered together with the solvent in a separation and recovery tank 306.In the separation and recovery tank 306, PU, ​​a component other than 3P, melts and floats on top of the solvent in which PE and PP have been dissolved, so the PU is recovered and discharged outside, and the solvent in which PE and PP have been dissolved is received in a filtration tank 308 and cooled, causing PE and PP to precipitate, so the PE and PP are filtered and recovered, and the solvent CHN is received in a solvent recovery tank 310 and returned to the dissolution and separation tank 301 by a circulation pump 311 for reuse. Note that since the pulp is impregnated with the solvent, it is recovered using a centrifuge as appropriate and recycled.

[0107] The method for separating and recovering composite plastic waste according to the present invention is revolutionary in that it can be applied to the regeneration of various composite plastics by combining (1) or (2) of the first step (A) with (1) or (2) of the second step (B) depending on the composition of various waste materials.

[0108] 10: Composite plastic waste separation and recovery device 12: Dissolving tank 14, 16, 18: First filtration tank 20, 22: Solid-phase polymerization evaporation vessel 24, 26: Separation solvent receiving tank 28: Heater 30: Stirrer 32: Flexible container bag 34: Valve device 36, 38, 40: Inlet side valve device 42, 44: Stirrer 48, 50: Valve device 53, 55: Vacuum system 56, 58, 70, 72: Pump 60, 62: Heater 64, 66, 68: Outlet side valve device 100: Clothing bleaching device 102: Mixing tank 104: Receiver with heater 106: Circulation pump 108: Evaporation tank 110: Vacuum receiving tank 112: Vacuum pump 114: Condenser 116: Dye recovery tank 120: Centrifugal drainer

Claims

1. A method for chemically recycling composite plastic waste containing various plastics by separating it into its components, comprising a first step (A) of separating a 3P plastics component containing polyethylene (PE), polypropylene (PP), and polystyrene (PS) from a plastic component other than 3P, wherein the first step (A) is: (1) using a glycol-based solvent that is not a solvent for dissolving 3P plastics but is a solvent for solvolysis of plastics other than 3P, melting the 3P plastics at a temperature at which plastics other than 3P are not melted and floating them on the solvent, while sedimenting the plastics other than 3P to separate the two by specific gravity, or (2) using a ketone-based or xylene-based solvent that is a solvent for dissolving 3P plastics but is not a solvent for dissolving plastics other than 3P, and dissolving the 3P plastics at its dissolution temperature to separate them from the plastics other than 3P. A method for chemical recycling of composite plastic waste, characterized in that it is such.

2. The method for chemical recycling of composite plastic waste according to claim 1, wherein in the first step, the 3P plastics separated by specific gravity separation using a glycol-based solvent as the first solvent are distilled to separate them from the glycol-based solvent.

3. The method for chemical recycling of composite plastic waste according to claim 1, wherein in the first step, the 3P plastics separated by dissolution using a ketone-based or xylene-based solvent as the second solvent are precipitated from the solvent by a temperature drop and separated from the solvent.

4. A method for chemical recycling of composite plastic waste containing various plastics, which separates the composite plastic waste into its components, comprising: a first step (A) of separating a 3P plastics component containing polyethylene (PE), polypropylene (PP) and polystyrene (PS) from a plastic component other than 3P plastics; and a second step (B) of separately recovering plastics other than 3P plastics into their respective plastic components, wherein the first step (A) is: (1) a step of using a glycol-based solvent which is not a solvent for dissolving 3P plastics but is a solvent for solvolysis of plastics other than 3P plastics, melting 3P plastics at a temperature at which plastics other than 3P plastics are not melted and floating them on the solvent, while sedimenting plastics other than 3P plastics to separate the two by specific gravity, or (2) a step of using a ketone-based or xylene-based solvent which is a solvent for dissolving 3P plastics but is not a solvent for dissolving plastics other than 3P plastics, dissolving 3P plastics to separate them from plastics other than 3P plastics, and the second step (B) is: (1) a step of using a glycol-based solvent which is a solvent for solvolysis of plastics other than 3P plastics remaining, taking out plastics other than 3P plastics out of the system without melting them, and rapidly cooling them with the glycol-based solvent for separation, or (2) a step of melting and separating plastics other than 3P plastics remaining using a glycol-based solvent at a temperature close to the boiling point of the solvent of 180 to 280 °C, and being selected from the group consisting of a combination of (1) of (A) and (1) of (B), a combination of (1) of (A) and (2) of (B), a combination of (2) of (A) and (1) of (B), and a combination of (2) of (A) and (2) of (B) according to the type of the composite plastic waste.

5. The composite plastic waste containing various plastics is composed of a 3P plastics component including polyethylene (PE), polypropylene (PP) and polystyrene (PS) and a plastic component other than 3P plastics. The first step (A) is a step of using a glycol-based solvent which is not a solvent for dissolving 3P plastics but a solvent for solvolysis of plastics other than 3P plastics, melting the 3P plastics at a temperature equal to or higher than its melting temperature and not melting the plastics other than 3P plastics, floating the 3P plastics on the solvent while sedimenting the plastics other than 3P plastics to separate the two by specific gravity. The second step (B) is a step of using a glycol-based solvent which is a solvent for solvolysis of the remaining plastics other than 3P plastics, taking out the plastics other than 3P plastics out of the system without melting them, rapidly cooling them and separating them. The chemical recycling method for composite plastic waste according to claim 4.

6. The composite plastic waste containing various plastics is composed of a 3P plastics component including polyethylene (PE), polypropylene (PP) and polystyrene (PS), a plastic component other than 3P plastics and a third component of cellulose, metal or reinforcing fiber. The first step (A) is a step of using a ketone-based or xylene-based solvent which is a solvent for dissolving 3P plastics and not a solvent for dissolving plastics other than 3P plastics, dissolving the 3P plastics at its dissolution temperature to separate them from the plastics other than 3P plastics. The second step (B) is a step of melt-separating the remaining plastics other than 3P plastics at a temperature close to the boiling point of 200 to 280 °C using a glycol-based solvent. The chemical recycling method for composite plastic waste according to claim 1.

7. The chemical recycling method for composite plastic waste according to any one of claims 1 to 6, wherein the glycol-based solvent contains one or more selected from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol.

8. The chemical recycling method for composite plastic waste according to any one of claims 1 to 6, wherein the ketone-based solvent contains cyclohexanone or methyl isobutyl ketone.

9. The chemical recycling method for composite plastic waste according to any one of claims 1 to 6, wherein the xylene-based solvent contains m-xylene, p-xylene or o-xylene or a mixture thereof.

10. The chemical recycling method of composite plastic waste according to any one of claims 1 to 6, wherein the composite plastic waste is an aluminum pouch and contains aluminum, PE, nylon, and PET.

11. The chemical recycling method of composite plastic waste according to any one of claims 1 to 6, wherein the composite plastic waste is a tent and contains PET and PE.

12. The chemical recycling method of composite plastic waste according to claim 1, wherein the composite plastic waste is mixed cotton fiber and contains PE, PP, and PU or PA.

13. The chemical recycling method of composite plastic waste according to claim 1, wherein the composite plastic waste is a paper diaper and contains cellulose in addition to PE and PU.

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