Method of recycling plastic molded container

Abstract

To provide a method for recycling a plastic molded container in which thermal deterioration of a resin material obtained from used plastic molded containers is reduced.SOLUTION: There is provided a method for recycling a plastic molded container, comprising: a collection step for collecting a used plastic molded container; a crushing step of crushing the collected used plastic molded container into plastic flakes; a washing step of washing plastic flakes during or after crushing in the crushing step; a drying step of drying the washed plastic flakes; a melting step of melting the dried plastic flakes into a melted object; and a molding step of molding a material containing the melted object into a plastic molded container.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recycling plastic molded containers. [Background technology]

[0002] Plastic molded containers (plastic molded containers) are widely used as containers for storing disinfectants, shampoos, hand soaps, body soaps, and other everyday products. In response to environmental issues and the need to reduce the use of plastic resources, it has become common to carry out material recycling from used plastic molded containers to obtain resin materials (recycled resin materials). Furthermore, horizontal recycling, in which similar plastic molded containers are formed using these resin materials, is also being practiced.

[0003] For example, Patent Document 1 discloses an extrusion blow molded container made of synthetic resin, the body of which forms the storage space for the contents and has a laminated structure made of multiple materials, the laminated structure having inner and outer layers made of virgin material and a recycled material layer located between the inner and outer layers, the recycled material layer being made of olefin-based recycled material obtained from crushed material obtained by crushing synthetic resin containers, and the weight proportion of the recycled material layer in the laminated structure being 50% or more and 90% or less. As described in Patent Documents 2 and 3, when horizontal recycling is performed, recycled resin pellets are usually formed from waste plastic materials, and these recycled resin pellets are used as recycled resin material (the recycled material used in the method of Patent Document 1 mentioned above is also a pellet). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-192998 A [Patent Document 2] JP 2018-008438 A [Patent Document 3] JP 2006-130756 A Summary of the Invention [Problem to be solved by the invention]

[0005] In this way, in the process of obtaining a resin material from a used plastic molded container, in order to improve moldability and machine suitability when forming a plastic molded container using this resin material, the used plastic molded container is usually crushed and thoroughly washed, and then heated or otherwise processed into recycled resin pellets with a uniform size of about several mm. However, such recycled resin pellets have the problem that they are prone to thermal degradation due to the thermal load during their formation, and are prone to coloring, etc. In particular, when recycled resin pellets are formed from used plastic molded containers made of polyolefin resin, this coloring is more likely to occur.

[0006] The present invention has been made in view of the above problems, and relates to a method for recycling plastic molded containers in which the resin material obtained from used plastic molded containers is less likely to be deteriorated by heat. [Means for solving the problem]

[0007] The present invention relates to a method for recycling plastic molded containers, which includes a recovery process for recovering used plastic molded containers, a crushing process for crushing the recovered used plastic molded containers into plastic flakes, a washing process for washing the plastic flakes during or after crushing in the crushing process, a drying process for drying the washed plastic flakes, a melting process for melting the dried plastic flakes into a molten material, and a molding process for molding a material containing this molten material into a plastic molded container. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for recycling plastic molded containers in which the resin material obtained from used plastic molded containers is less susceptible to thermal degradation. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a process diagram showing an example of a method for recycling plastic molded containers according to the present embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an example of plastic flakes obtained in the crushing step of the method for recycling plastic molded containers according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, in some drawings, there are some parts that are not given reference numerals (omitted) for convenience. Furthermore, the dimensional ratios of each component shown in the drawings may differ from the actual dimensional ratios in order to facilitate understanding of the invention.

[0011] 〔overview〕 First, an outline of an embodiment of a method for recycling plastic molded containers according to the present invention will be described with reference to FIG. The method for recycling plastic molded containers according to the present invention includes the following embodiments.

[0012] The recycling method for plastic molded containers in this embodiment includes a recovery process (S1) for recovering used plastic molded containers, a crushing process (S2) for crushing the recovered used plastic molded containers into plastic flakes, a washing process (S3) for washing the plastic flakes during or after crushing in the crushing process, a drying process (S4) for drying the washed plastic flakes, a melting process (S5) for melting the dried plastic flakes into a molten material, and a molding process (S6) for molding a material containing the molten material into a plastic molded container (Figure 1).

[0013] In other words, the method for recycling plastic molded containers according to this embodiment is a method for recycling or regenerating plastic molded containers (a material recycling method or horizontal recycling method) in which, as shown in FIG. 1, used plastic molded containers are collected, plastic flakes are formed as recycled resin material (recycled material), and these plastic flakes are used to form plastic molded containers as recycled products.

[0014] [Steps of the method for recycling plastic molded containers according to this embodiment] Next, each step of the method for recycling plastic molded containers according to this embodiment will be described in detail with reference to Figs. As described above, the method for recycling plastic molded containers according to this embodiment includes at least the steps of (S1) recovery, (S2) crushing, (S3) cleaning, (S4) drying, (S5) melting, and (S6) molding. Each step will be described in detail below.

[0015] <Recovery process> In the method for recycling plastic molded containers according to this embodiment, first, a recovery step is carried out in which used plastic molded containers are recovered as shown in (S1) of FIG. Here, "collecting used plastic molded containers" in the plastic molded container recycling method according to the present invention includes not only collecting used plastic molded containers as they are, but also collecting used plastic molded containers from which caps, pump-equipped caps, spouts, etc. have been removed. Therefore, this collection step also includes an embodiment in which the container bodies of used plastic molded containers are separated and collected. Note that separating pump-equipped caps and the like and separating and collecting the container bodies of used plastic molded containers is preferable because it makes recycling easier and allows for the production of higher quality plastic molded containers.

[0016] Therefore, in this recovery process, the used plastic molded containers to be recovered are configured to have an opening capable of containing and discharging contents, such as an opening with a plug structure that can be opened and closed repeatedly (such as an opening with a thread), and the containers may be recovered in an open state with the opening.

[0017] The contents contained in the used plastic molding containers recovered in this recovery process are preferably liquids with a total content of water and ethanol of 30 wt% or more and a viscosity of 10,000 mPa·s or less at 30°C. In other words, in this recovery process, it is preferable to separate and recover the used plastic molding containers in which the liquids were contained. This is because, in the washing process described below, the amount of remaining contents (adhesion amount) of the crushed plastic flakes can be easily reduced with water or hot water, making the washing process easier. Also, this is because, in the drying process described below, the moisture content of the plastic flakes can be easily reduced.

[0018] The total content of water and ethanol in this liquid is more preferably 33 wt% or more, even more preferably 40 wt% or more, even more preferably 50 wt% or more, and even more preferably 55 wt% or more. The viscosity of this liquid at 30°C is a value measured by a B-type viscometer (for example, Viscometer TV-10 or Viscometer TVB-10 manufactured by Toki Sangyo Co., Ltd.) (the same applies below), and is more preferably 6000 mPa·s or less, even more preferably 5000 mPa·s or less, even more preferably 1000 mPa·s or less, even more preferably 800 mPa·s or less, even more preferably 500 mPa·s or less, even more preferably 100 mPa·s or less, and even more preferably 50 mPa·s or less. The lower limit may be 1 mPa·s or more.

[0019] Such liquids include disinfectants, shampoos (including foam types that become foam when dispensed), hand soaps (including foam types), body soaps (including foam types), rinses, etc. Among these, disinfectants, foam-type shampoos, foam-type hand soaps, and foam-type body soaps are particularly preferred.

[0020] Furthermore, it is more preferable that the contents contained in the used plastic molded container are a liquid containing an ionic surfactant, and that the plastic flakes before the washing step described below contain 5 ppm (0.0005 wt%) or more of the ionic surfactant derived from this liquid. In other words, it is preferable that a predetermined amount or more of the ionic surfactant derived from this liquid is attached (remains) to the plastic flakes before the washing step. The ionic surfactant remaining in a small amount on the plastic flakes enhances the washing effect of the plastic flakes with water or hot water in the washing step described below, and the quality of the plastic flakes after washing can be improved even with simple washing, and the moldability and the physical properties (bottle physical properties, resin physical properties, etc.) of the obtained plastic molded container can be improved. Although the upper limit is not limited, it is more preferable that it is 5000 ppm or less, more preferably 3000 ppm or less, and even more preferably 2000 ppm or less.

[0021] The ionic surfactant may be any of cationic surfactant, anionic surfactant, and amphoteric surfactant, but is more preferably cationic surfactant or anionic surfactant. Examples of cationic surfactants include quaternary ammonium salts (benzalkonium chloride, trimethylammonium chloride, etc.) and alkylamine salts. Examples of anionic surfactants include sulfate esters (polyoxyethylene lauryl ether ammonium sulfate, sodium laureth sulfate, etc.), carboxylic acids (polyoxyethylene lauryl ether carboxylic acid, etc.), and sodium cocoyl methyl taurate. Examples of amphoteric surfactants include carboxybetaine (cocamidopropyl betaine, etc.) and alkylamine oxide.

[0022] It is more preferable that the liquid contained in the used plastic molding container further contains a polyhydric alcohol or a polyhydric alcohol ester in addition to the ionic surfactant, and that the plastic flakes before the washing step described below contain a total of 100 ppm (0.01 wt%) or more of the ionic surfactant and the polyhydric alcohol or the polyhydric alcohol ester derived from this liquid. In other words, it is more preferable that a predetermined amount or more of the ionic surfactant and the polyhydric alcohol or the polyhydric alcohol ester derived from this liquid adheres (remains) to the plastic flakes before the washing step. This is because the ionic surfactant and the polyhydric alcohol or the polyhydric alcohol ester remaining in a small amount on the plastic flakes further enhances the washing effect of the plastic flakes with water or hot water in the washing step described below, and the quality of the plastic flakes after washing can be further improved even with simple washing. Although the upper limit is not limited, it is more preferable that it is 8000 ppm or less, more preferably 5000 ppm or less, and even more preferably 3000 ppm or less.

[0023] Preferred polyhydric alcohols include glycerin, propylene glycol, polyethylene glycol, sorbitol, etc. Preferred polyhydric alcohol esters include esters of the above-mentioned polyhydric alcohols and fatty acids (propylene glycol laurate, etc.).

[0024] As described above, such liquids include disinfectants, shampoos (including foam types), hand soaps (including foam types), body soaps (including foam types), rinses, etc. In particular, disinfectants, foam shampoos, foam hand soaps, and foam body soaps are more preferable.

[0025] The used plastic molded containers recovered in this recovery step are preferably made of polyethylene-based resin or polypropylene-based resin, because this makes separation and recovery easy, and furthermore, the plastic flakes obtained from used plastic molded containers made of such polyethylene-based resin or polypropylene-based resin are easy to extrusion blow mold. Here, "composed of polyethylene-based resin or polypropylene-based resin" means that the mass proportion of polyethylene-based resin or polypropylene-based resin in the total mass is 70% or more (the same applies below), more preferably 80% or more, even more preferably 90% or more, and even more preferably 95% or more.

[0026] The polyethylene resin includes high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra-low density polyethylene (ULDPE), etc. Also included is biopolyethylene (BioPE) obtained by dehydrating and polymerizing bioethanol produced from sugarcane molasses, etc. Also included is ethylene-vinyl alcohol copolymer (EVOH) that can impart oxygen barrier properties. And, it may be a product that uses (is configured by) mixing two or more of these. Also, the used plastic molded containers recovered in this recovery process may be a product that uses such a polyethylene resin and a polypropylene resin in combination.

[0027] However, the used plastic molded containers collected in this collection process may be made of polyester-based resins, such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (amorphous PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN).

[0028] Even in this case, in the plastic molded container recycling method according to the present embodiment, it is more preferable that the used plastic molded containers to be collected in the collection step are made of the same type of plastic material. For example, it is more preferable to select any one of the following in the collection step: used plastic molded containers made of polyethylene resin, used plastic molded containers made of polypropylene resin, or used plastic molded containers made of polyester resin.

[0029] In addition, the used plastic molded containers collected in this recovery process are preferably uncolored plastic molded containers (natural bottles). In other words, they are preferably plastic molded containers that are not printed or bottle-colored. Therefore, the recovery process may further include a sorting process for sorting the used plastic molded containers that are collected or have been collected in this recovery process based on whether they are colored or not.

[0030] <Crushing process> In the method for recycling plastic molded containers according to this embodiment, after the above-mentioned recovery step, a crushing step is carried out in which the recovered used plastic molded containers are crushed into plastic flakes as shown in (S2) of Fig. 1 and Fig. 2. This crushing is not limited, but the used plastic molded containers may be made into flakes using a known crusher (e.g., JC-10 type manufactured by Morita Seiki Co., Ltd.) having a member capable of cutting and crushing, such as a cutting cutter.

[0031] In this crushing step, it is preferable to make the plastic flakes obtained a size that passes through a mesh with an opening of 8 mm (8 mm mesh pass product). This is because the frequency of collision of the plastic flakes increases in the cleaning step described below, and the cleaning efficiency increases. In particular, in the case of plastic flakes containing 5 ppm or more of an ionic surfactant derived from a liquid contained in a used plastic molding container, or plastic flakes containing a total of 100 ppm or more of an ionic surfactant and a polyhydric alcohol or a polyhydric alcohol ester, as shown in FIG. 2, the surface area of ​​the area to which these are not attached is moderately increased (such as the area indicated by reference numeral 13 in FIG. 2), which makes it easier to exert the synergistic effect of the above-mentioned frequency of collision, the moderate increase in surface area, and the ionic surfactant, etc., and the cleaning effect in the cleaning step is further improved. Furthermore, if the size is made to be such, it is easy to improve the workability and machine suitability in the subsequent melting and molding steps.

[0032] Here, the mesh with an 8 mm opening is the distance between the wires facing each other at the mesh opening (the same applies below). And, although not limited thereto, from the viewpoint of workability in the molding process, the proportion of plastic flakes obtained in this crushing process that are large enough to pass through a mesh with an opening of 5 mm (5 mm mesh pass products) may be less than 10%.

[0033] <Cleaning process> In the method for recycling plastic molded containers according to this embodiment, a washing step is performed during or after the crushing in the crushing step described above to wash the plastic flakes ((S3) in FIG. 1). In other words, the plastic flakes may be washed almost simultaneously with or immediately after crushing, or the crushed plastic flakes may be collected and washed separately.

[0034] The washing of the plastic flakes is performed to remove foreign matter other than plastics and components derived from the contents, and simple washing can be performed using water, hot water, etc. For example, in this washing process, a method is shown in which the plastic flakes introduced into a foreign matter removal device or the like are brought into contact with water or hot water to remove foreign matter mixed in the plastic flakes and wash the plastic flakes. That is, in the recycling method for plastic molded containers according to this embodiment, it is possible to obtain a sufficient washing effect while making the water or hot water used in the washing process substantially free of components other than water, such as detergents. In particular, when the contents contained in the used plastic molded container as described above are liquids with a total content of water and ethanol of 30 wt% or more and a viscosity of 10,000 mPa·s or less at 30°C, the washing effect by the water or hot water is more easily obtained.

[0035] Furthermore, as mentioned above, when the contents contained in the used plastic molding container are liquids containing an ionic surfactant or liquids containing a polyhydric alcohol or a polyhydric alcohol ester in addition to the ionic surfactant, and the crushed plastic flakes contain a predetermined amount or more of the ionic surfactant, polyhydric alcohol, or polyhydric alcohol ester derived from the liquid, the above-mentioned cleaning effect is also more easily obtained. In this case, when the plastic flakes collide with each other in the cleaning process, the ionic surfactant, etc. contained in the plastic flakes (adhered to some surfaces as shown in Figure 2) acts locally, thereby enhancing the cleaning effect, and the ionic surfactant, etc. are removed from the plastic flakes together with other components by this cleaning. In particular, when the plastic flakes are made to a size that can pass through a mesh with an opening of 8 mm, this effect is more easily achieved.

[0036] Furthermore, when hot water is used in this washing step, the temperature is preferably 30°C or higher, more preferably 40°C or higher, from the viewpoint of efficiently removing components derived from the contents. The upper limit is preferably 60°C or lower, more preferably 50°C or lower, from the viewpoint of ease of temperature control in the washing step. The method of washing the plastic flakes in this washing step may be, for example, a method of putting the plastic flakes into a tank containing water or hot water, stirring them, and rinsing them if necessary, or a method of spraying water or hot water on the plastic flakes discharged from a crusher before or after sorting. Furthermore, physical dehydration (centrifugation, etc.) may be performed if necessary.

[0037] <Drying process> In the recycling method for plastic molded containers according to this embodiment, after the washing step, a drying step is performed to dry the washed plastic flakes ((S4) in FIG. 1). The method for drying the plastic flakes is not limited, but may be ventilation drying using a known dryer (for example, a hot air dryer Dry Jet manufactured by Nippon Seam Co., Ltd.). The drying temperature (ambient temperature when drying the plastic flakes) is also not particularly limited, but since it is easy to suppress discoloration (browning) and thermal deterioration of the plastic flakes, a drying temperature of less than 100°C is more preferable, a drying temperature of 80°C or less is even more preferable, and a drying temperature of 60°C or less is even more preferable, and natural drying at room temperature (10 to 40°C) may also be used.

[0038] In this drying step, it is preferable that the moisture content of the dried plastic flakes is 1 wt% or less. This is because foaming during molding is less likely to occur, and the quality of the resulting plastic molded container is improved. This moisture content is more preferably 0.8 wt% or less, and even more preferably 0.5 wt% or less. For example, if the contents contained in the used plastic molded container are a liquid with a total water and ethanol content of 30 wt% or more and a viscosity of 10,000 mPa·s or less at 30°C, the moisture content can easily be reduced to 1 wt% or less even by natural drying at room temperature after the above-mentioned cleaning step.

[0039] <Melting process and molding process> The recycling method for plastic molded containers according to this embodiment involves a melting process in which dried plastic flakes are melted to form a molten material, and a molding process in which a material containing this molten material is molded into a plastic molded container (S5 and S6 in FIG. 1).

[0040] In the melting process, the dried plastic flakes are simply filled into a tank or hopper and heated to a temperature higher than their melting point. For example, in the case of plastic flakes obtained from used plastic molding containers made of polyethylene resin, they can be made into a molten material by heating to about 170 to 180°C.

[0041] This melting process may include a process of mixing virgin plastic material (new plastic material produced from raw materials such as petroleum). For example, dried plastic flakes may be mixed with a virgin plastic material in a similar flake form and melted, or a melt of dried plastic flakes may be mixed with a melt of virgin plastic material melted in a similar manner.

[0042] In the molding process, the material containing the melted plastic flakes as described above may be molded into a plastic molded container by blow molding, etc. For example, a direct blow molding machine (such as TPF-454 manufactured by Tahara) is used to extrude the material softened by heating to form a parison (cylindrical molding), and the molded parison is then sandwiched between metal molds to blow air into the interior, and after cooling, the metal mold is opened to remove the molded product, thereby obtaining a plastic molded container.

[0043] The molding method in this molding process is not limited to blow molding, and any known molding method for plastic molded containers, such as injection molding, can be used. However, since it is easy to mold a material containing molten dried plastic flakes, it is more preferable that this process be a blow molding process.

[0044] The method for recycling plastic molded containers according to the present embodiment may further include other steps as long as it includes the above-mentioned steps. For example, it may include a pretreatment step of performing simple cleaning and drying of used plastic molded containers before the crushing step, and an attachment step of attaching shrink wrap or the like to the molded plastic molded container. However, the method for recycling plastic molded containers according to the present embodiment is characterized in that it does not include a resin pellet forming step of applying a heat load to the crushed plastic flakes to form resin pellets (recycled resin pellets) with a uniform size in the form of grains of about several mm. By not including this resin pellet forming step, it is possible to reduce the thermal deterioration of the resin material (recycled resin material) obtained from the used plastic molded containers, and it is possible to maintain the quality (bottle physical properties, resin physical properties) of the obtained plastic molded containers at a high level. In addition, the flake-shaped resin material obtained from this used plastic molded container can be obtained by simple cleaning, and furthermore, the moldability and machine suitability of the plastic molded container can be maintained at a high level. In other words, it is less likely to affect the moldability and the like. In this way, a horizontal recycling system can be constructed in which used plastic molded containers after the contents contained therein have been used up are used as recycling raw materials for producing plastic molded containers.

[0045] Then, by using such a plastic molded container obtained by the recycling method of the plastic molded container according to the present embodiment, a container-packed product can be obtained in which an object is accommodated in the accommodation area. The type of object accommodated in this plastic molded container is not particularly limited, but examples include disinfectant, shampoo, hand soap, and body soap, and it is preferable that the object is a liquid object. In particular, if the object is a liquid object containing one or more selected from the group consisting of ionic surfactants, polyhydric alcohols, and polyhydric alcohol esters, having a total content of water and ethanol of 30 wt% or more, and having a viscosity of 10,000 mPa·s or less at 30°C, as described above, this object can be easily recycled after use. However, objects other than liquid objects (such as powders and granular objects) may also be accommodated.

[0046] Furthermore, in the plastic molded container recycling method according to this embodiment, it is more preferable that the used plastic molded containers recovered in the recovery process are transported directly to a container molder (such as a container molding company) that carries out the molding process, and that the crushing, cleaning, drying, melting, and molding processes are all carried out by this container molder.

[0047] Conventionally, when plastic molded containers are recycled, the collected used plastic molded containers are made into recycled resin pellets. However, container molders and the like are usually unable to turn the containers into resin pellets due to reasons such as equipment limitations. Therefore, the collected used plastic molded containers are first transported to a resin pellet former (such as a resin pellet manufacturer) to be turned into recycled resin pellets, and the resulting recycled resin pellets are then transported to the container molder.

[0048] However, as described above, the method for recycling plastic molded containers according to this embodiment does not include a resin pellet formation process, and therefore collected used plastic molded containers can be transported directly to the container molder (without going through an intermediate processor such as a resin pellet manufacturer) to be molded into plastic molded containers, thereby reducing transportation costs, shortening time, and streamlining storage and quality control by concentrating the materials in one location.

[0049] For example, the method preferably includes a recovery process for recovering used plastic molded containers, a transport process for transporting the recovered used plastic molded containers directly to a container molder who performs the molding process described below, a crushing process by the container molder to crush the used plastic molded containers into plastic flakes, a cleaning process for cleaning the plastic flakes during or after crushing in the crushing process, a drying process for drying the cleaned plastic flakes, a melting process for melting the dried plastic flakes into a molten material, and a molding process for molding a material containing the molten material into a plastic molded container.

[0050] Furthermore, this method is preferable because it results in a more efficient recycling system if used plastic molded containers used by users are collected by a product seller (distributor) such as a retail store, and the collected used plastic molded containers are transported directly to the container molder by the transporter that transported the plastic molded containers (products) containing the contents to the product seller. [Explanation of symbols]

[0051] S1 Recovery process S2 crushing process S3 Washing process S4 Drying process S5 Melting Process S6 Molding process 10 Plastic flakes 11 Surface of used plastic molded containers that was in contact with the contents 13 Surface exposed by fracture 15 Surface that was the outer surface of a used plastic molded container

Claims

1. A recycling step of collecting used plastic molded containers; A crushing step of crushing the collected used plastic molded containers into plastic flakes; A washing step of washing the plastic flakes during or after crushing in the crushing step; A drying step of drying the washed plastic flakes; A melting step of melting the dried plastic flakes into a melt; A molding step of molding the material containing the melt into a plastic molded container, and A method for recycling plastic molded containers.

2. The recycling method of the plastic molded container according to Claim 1, wherein the content contained in the used plastic molded container is a liquid material having a total content of water and ethanol of 30 wt% or more and a viscosity at 30 ° C of 10,000 mPa·s or less.

3. The content contained in the used plastic molded container is a liquid material containing an ionic surfactant, and The plastic flakes before performing the washing step contain 5 ppm or more of the ionic surfactant derived from the liquid material. The recycling method of the plastic molded container according to Claim 1 or 2.

4. The liquid material contained in the used plastic molded container further contains a polyhydric alcohol or a polyhydric alcohol ester, and The plastic flakes before performing the washing step contain 100 ppm or more in total of the ionic surfactant and the polyhydric alcohol or the polyhydric alcohol ester derived from the liquid material. The recycling method of the plastic molded container according to Claim 3.

5. The washing step is a step of bringing the plastic flakes into contact with water or warm water to remove foreign substances mixed in the plastic flakes and wash the plastic flakes. The recycling method of the plastic molded container according to Claim 1 or 2.

6. The recycling method of the plastic molded container according to Claim 1 or 2, wherein the used plastic molded container is made of a polyethylene-based resin or a polypropylene-based resin.

7. The plastic flakes obtained in the crushing step have a size that passes through a mesh with an opening of 8 mm. The recycling method of the plastic molded container according to Claim 1 or 2.

8. The method for recycling a plastic molded container according to claim 1 or 2, wherein the water content of the plastic flakes dried in the drying step is 1 wt% or less.

9. The method for recycling a plastic molded container according to claim 1 or 2, including a step of mixing virgin plastic material in the melting step.

10. The method for recycling a plastic molded container according to claim 1 or 2, wherein the used plastic molded container recovered in the recovery step is directly transported to the container molder who performs the molding step, and the container molder performs all of the crushing step, the washing step, the drying step, the melting step, and the molding step.

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