JP7669864B2 - Recycling method and manufacturing method for polyester resin containers - Google Patents

Description

The present invention relates to a method for recycling polyester resin containers in which collected used polyester resin containers are turned into raw materials and reused in the manufacture of new polyester resin containers, and to a method for manufacturing polyester resin containers suitable for such recycling.

Conventionally, polyester resin containers are made by producing a cylindrical preform with a bottom using synthetic resin such as polyethylene terephthalate, and then molding this preform into a bottle by stretch blow molding or the like, and are used in a wide range of fields as containers for various beverages, seasonings, and the like. This type of container is generally known as a PET bottle, and in recent years, due to social demand, a circular PET bottle recycling technology called "bottle-to-bottle" has been considered, in which used PET bottles are collected, recycled into raw materials, and reused in new PET bottles.

For example, Patent Document 1 discloses a technology for mechanical recycling in which used plastic bottles are crushed and washed to produce resin flakes, contaminants contained in the resin flakes are decontaminated by volatilizing them through heating under vacuum, and the flakes are then fed in a molten state through a filter to an injection molding machine to injection mold preforms.

Special table 2019-514728 publication

However, in a circular recycling technology in which used PET bottles are collected and new PET bottles (recycled PET bottles) are produced from mechanically recycled materials made from the collected PET bottles, the collected PET bottles include recycled PET bottles produced from recycled materials that have already been regenerated one or more times. When PET bottles are repeatedly reused in this way to produce PET bottles, foreign matter remaining in the recycled materials may be mixed in, and the recycled materials may deteriorate due to the repeated heat history they are subjected to in the pelletizing process for the recycled materials and the PET bottle manufacturing process, causing the manufactured PET bottles to yellow or lose transparency, resulting in a deterioration in the color of the PET bottles. Furthermore, the use of deteriorated recycled materials may cause various problems, such as a decrease in the container performance of the PET bottles and fluctuations in the molding conditions during PET bottle manufacturing, resulting in a decrease in the productivity of PET bottles.

To address these issues, it has been considered to mix recycled materials with resin materials that have not been subjected to a regeneration process (virgin materials) to prevent the resin from losing its color and to improve the material properties. However, from the perspective of recycling activities to address environmental issues, there has been a recent trend toward recycled PET bottles made from 100% recycled materials.
It is also possible to blend colorants such as pigments into recycled materials to make colored PET bottles, thereby preventing the color of the recycled PET bottles from appearing to have deteriorated. However, resin materials that have been blended with colorants are then limited in the uses for which they can be reused.

Therefore, the inventors of the present invention have conducted extensive research to solve the above-mentioned problems in the "bottle-to-bottle" recycling cycle, in which collected used polyester resin containers are turned into raw materials and reused to manufacture new polyester resin containers, and as a result have completed the present invention.

The method for recycling polyester-based resin containers according to the present invention is a method for recycling polyester-based resin containers in which collected used polyester-based resin containers are recycled into raw materials and reused in the manufacture of new polyester-based resin containers . A non-recycled container manufactured using virgin materials that have not been recycled, or a recycled container manufactured using recycled materials that have been recycled at least once, is provided with an identification mark on at least one of a neck ring provided at the mouth or a neck part of the mouth. The collected used polyester-based resin containers are separated into the non-recycled containers and the recycled containers based on the presence or absence of the identification mark, and the non-recycled containers are separately sorted into primary recycled materials that have been recycled into raw materials by recycling the non-recycled containers, and secondary recycled materials that have been recycled into raw materials by recycling the recycled containers, and either one or both of the primary recycled materials and the secondary recycled materials are reused to manufacture the new polyester-based resin containers.

The manufacturing method of polyester-based resin containers according to the present invention is a manufacturing method of polyester-based resin containers in which collected used polyester-based resin containers are turned into raw materials and reused to manufacture new polyester-based resin containers, and an identification mark is provided on at least one of a neck ring provided on the mouth of a non-recycled container manufactured using virgin materials that have not been subjected to a recycling process or a recycled container manufactured using recycled materials that have been subjected to at least one recycling process, and the non-recycled containers and the recycled containers are separated from the collected used polyester-based resin containers based on the presence or absence of the identification mark, and the non-recycled containers are separately sorted into primary recycled materials that have been recycled into raw materials by recycling the non-recycled containers and secondary recycled materials that have been recycled into raw materials by recycling the recycled containers, and either one or both of the primary recycled materials and the secondary recycled materials are reused to manufacture the new polyester-based resin containers.

According to the present invention, in a recycling cycle in which collected used polyester resin containers are turned into raw materials and reused to manufacture new polyester resin containers, it is possible to stably manufacture recycled polyester resin containers that suppress deterioration of the color and deterioration of the material properties of the recycled materials that are repeatedly reused.

1 is a perspective view showing an outline of a polyester-based resin container according to an embodiment of the present invention. FIG. 1 is a perspective view showing an outline of a preform according to an embodiment of the present invention. FIG. 2 is an explanatory view showing another example of a polyester-based resin container according to the present invention.

A preferred embodiment of the present invention will now be described with reference to the drawings.

In this embodiment, collected used polyester-based resin containers are turned into raw materials and reused to manufacture new polyester-based resin containers by blow molding.The collected used polyester-based resin containers are separated into non-recycled containers manufactured using virgin materials that have not been recycled and recycled containers manufactured using recycled materials that have been recycled at least once, and the non-recycled containers are separately sorted into primary recycled materials made into raw materials by recycling the non-recycled containers and secondary recycled materials made into raw materials by recycling the recycled containers, and either one or both of the primary recycled materials and the secondary recycled materials are reused to manufacture new polyester-based resin containers.
In this way, by appropriately selecting resin material obtained from non-recycled containers made using virgin materials (used for the first recycling round) and resin material obtained from recycled containers made using recycled materials (used for the second recycling round or later), and mixing either one of the materials, or both of these resin materials in a predetermined ratio, to produce a mixed recycled material for the production of new containers, it is possible to produce recycled PET bottles made from 100% recycled materials while effectively suppressing deterioration of color and material properties.
Furthermore, according to a circular recycling method for polyester-based resin containers, including the above-mentioned manufacturing method, in which collected used containers are turned into raw materials and reused in the manufacture of new containers, it is possible to stably produce recycled polyester-based resin containers in which deterioration of the resin's color and degradation of the material properties are more effectively suppressed, and it is possible to continuously carry out ``bottle-to-bottle'' recycling.

In addition, this embodiment can include a process for determining whether or not the secondary recycled material is suitable for reuse, as described below. This allows the secondary recycled material to be separated into reusable and difficult to reuse secondary recycled materials, and the difficult to reuse secondary recycled material to be removed from the recycling process, making it possible to more effectively suppress deterioration of color and material properties in the "bottle-to-bottle" recycling cycle, while more stably producing recycled PET bottles made from 100% recycled material.

[Recyclable]
First, in this embodiment, an example of a polyester resin container to be recycled will be described.
FIG. 1 is a perspective view showing an example of a polyester resin container to be recycled.

The container 1 shown in FIG. 1 includes a mouth 2, a shoulder 3, a body 4, and a bottom 5, and has a container shape called a round bottle, in which the body 4 is formed into a cylindrical shape, but there are also container shapes called square bottles, in which the body 4 is formed into a square tube shape.

The mouth 2 is a cylindrical portion that serves as an outlet for pouring the liquid content, and a screw thread 2a is provided on the side of the open end of the mouth 2 for attaching a cap (not shown).
In addition, the mouth portion 2 is provided with an annular neck ring 2b that protrudes outward in the circumferential direction, and the mouth portion 2 includes a neck portion 2c that hangs down cylindrically of roughly the same diameter from just below the neck ring 2b. In many cases, the shape and dimensions of the mouth portion 2 are designed to be roughly the same so that a standardized lid can be attached in common.

Here, the top, bottom, left, right and length and width directions of the container 1 are defined when it is held upright with the mouth 2 side facing up. Similarly, the top, bottom, left, right and length and width directions of the preform 10, which will be described later, are defined when it is held with the mouth 20 side facing up.

The container 1 shown in FIG. 1 has a bottom 5 formed in a so-called petaloid shape so that it is suitable for use with carbonated beverages, but there are also containers with bottoms 5 of other shapes that are suitable for use with non-carbonated beverages, various seasonings, etc.

In this embodiment, all containers generally referred to as PET bottles, such as the container 1 shown in Figure 1, can be recycled.

Such a container 1 can be manufactured by preparing a preform 10 using a thermoplastic resin, which is molded into a cylindrical shape with a bottom by injection molding, compression molding, or the like, and then molding this preform 10 into a desired container shape by biaxial stretch blow molding, or the like.

Figure 2 shows an example of a preform 10 to be blow molded into a container 1. The preform 10 is formed in a bottomed tubular shape including a mouth 20 that opens at the top and a body 30 that is closed at the bottom. The mouth 20 of the preform 10 is not stretched by blow molding, and is the portion that will become the mouth 2 of the container 1 while generally maintaining its appearance. The mouth 20 of the preform 10 is provided with a screw thread 2a and a neck ring 2b, which are indicated by the same reference numerals as those given to the container 1. The portion below the neck ring 2b of the mouth 20 of the preform 10 becomes the neck portion 2c of the container 1.

As the thermoplastic resin used, polyethylene terephthalate and other thermoplastic polyester resins have traditionally been preferred, as is reflected in the name PET bottles, but the method can generally be applied to any recyclable polyester resin, whether aromatic or aliphatic.

In recent years, attempts have been made to increase the proportion of plant-derived biomass plastics used in order to avoid the use of materials derived from petroleum-based fossil fuels. For example, attempts have been made to use polyester-based resins with an increased biomass content by using ethylene glycol derived from plant-derived bioethanol as a diol component. Naturally, polyester-based resins with ethylene glycol as a diol component derived from plant-derived bioethanol and polyester-based resins with ethylene glycol as a diol component derived from petroleum-based fossil fuels have the same molecular structure derived from ethylene glycol and the same chemical and physical properties, so in this embodiment, PET bottles manufactured using such plant-produced polyester-based resins with an increased biomass content are also eligible for recycling.

Therefore, when repeating the "bottle-to-bottle" recycling cycle, since both petroleum-based fossil fuel-derived polyester resins and plant-derived polyester resins can be used without distinction as the same resin material, the recycled material made from recovered PET bottles may contain a mixture of petroleum-based fossil fuel-derived polyester resins and plant-derived polyester resins.

Containers made from polyester resins with ethylene glycol as the diol component, made from plant-derived bioethanol, can be verified for the presence of biomass polyester by measuring carbon-14 with an accelerator mass spectrometer (AMS). The composition ratio of biomass polyester can also be calculated from the radiation count (CPM) (counts per minute) intensity.

[Identification mark]
In this embodiment, when separating non-recycled containers manufactured using virgin materials that have not undergone recycling processing from recycled containers manufactured using recycled materials that have undergone at least one recycling process, it is preferable to provide an identification mark 6 on the non-recycled container or the recycled container so that the non-recycled containers and the recycled containers can be easily separated based on the presence or absence of the identification mark 6.

In addition, used containers 1 are generally collected in a reduced volume state, such as by being crushed, but since the mouth 2 is difficult to crush even when the container 1 is crushed, in many cases the mouth 2 of the collected container 1 maintains its original shape. In addition, the mouth 2 of the collected container 1 may still have a cap band remaining above the neck ring 2b, or the cap may still be attached.

In view of these points, it is preferable that the identification mark 6 be provided on at least one of the neck ring 2b on the mouth 2 or the neck portion 2c of the mouth 2, which is not crushed during collection and is not hidden by a cap or cap band, so that the identification mark 6 can be easily recognized from the outside of the collected container 1.

The identification mark 6 may be provided in a form that allows the container 1 to be visually identified, and is not particularly limited thereto. From the viewpoint of recycling, however, it is preferable that the identification mark 6 be provided in a form that allows the container 1 to be identified without using a coloring agent.
For example, the identification mark 6 can be attached without using a coloring agent by at least partially heating the neck ring 2b or the neck portion 2c and using the whitened portion as the identification mark 6. In this case, as shown in Fig. 1, the identification mark 6 may be provided on the peripheral edge of the neck ring 2b, or on the neck portion 2c, specifically, at a position up to 5 mm directly below the neck ring 2b.
Alternatively, as shown in FIG. 3, a notch 61 may be provided on the peripheral edge side of the neck ring 2b, and serve as an identification mark 6 that can be identified by the shape of the neck ring 2b.

Although it is possible to manually separate non-recyclable containers from recyclable containers using such identification marks 6, it is more efficient and preferable to use a device with an identification function according to the shape of the identification mark 6, such as image processing or color inspection processing, to separate them functionally.

The identification mark 6 can be provided after the preform 10 has been molded into a predetermined container shape by blow molding or the like, or can be provided during the stage of manufacturing the preform 10 to be blow molded into the container 1.
As described above, the mouth 20 of the preform 10 is not stretched by blow molding, and generally maintains its appearance to become the mouth 2 of the container 1. Therefore, by providing the identification mark 6 on the neck ring 2b of the preform 10 or on the lower part of the neck ring 2b, the identification mark 6 is also provided on the neck ring 2b or the neck part 2c of the container 1 in the same manner.

To create a whitened area due to thermal crystallization on the mouth 2 of the container 1, the area to be thermally crystallized can be heated for 20 to 150 seconds at a temperature, for example, that is the crystallization temperature Tc of typical polyethylene terephthalate ±5°C.

To provide the notch 61 in the neck ring 2b of the container 1, a protrusion of the desired shape can be provided at a position corresponding to the notch 61 in the neck ring 2b of the molding die when molding the preform 10.

The method of separating PET bottles collected from the market into non-recycled and recycled containers by providing the identification mark 6 can only become an effective separation method if it is made into a social rule. In other words, it can only become an effective separation method if it is implemented uniformly throughout the community or society as a whole. Therefore, whether to provide the identification mark 6 on a non-recycled container or a recycled container should be selected taking into consideration the overall consumer awareness, the establishment of social systems, and the industrial convenience of the separation system (equipment). However, since non-recycled containers are manufactured using resin materials (virgin materials) that have not been subjected to a recycling process, the origin of the resin materials is clear, and it is clear that recycled materials that have been recycled at least once are not used, it is considered convenient for classifying materials, so it is preferable to provide the identification mark 6 on non-recycled containers.

[Determining whether or not secondary recycled materials can be reused]
When using secondary recycled materials from the second or subsequent recycling rounds to manufacture new recycled containers, it is inevitable that the secondary recycled materials will gradually contain larger amounts of resin components that have deteriorated as a result of repeated recycling processes in the "bottle-to-bottle" recycling cycle, and the use of secondary recycled materials that contain large amounts of deteriorated resin components is not desirable from the perspective of quality control of the newly manufactured recycled containers.
Therefore, it is preferable to appropriately remove secondary recycled materials that contain a large amount of resin components that have been degraded through repeated regeneration processes from the "bottle-to-bottle" recycling cycle.

In view of this, this embodiment can further include a step of determining whether or not the secondary recycled material can be reused.

One example is a method for determining whether or not a secondary recycled material can be reused by utilizing the property that the crystallization temperature Tc of the material decreases with repeated regeneration treatment. In this method, the secondary recycled material obtained is heated, and the condition of the secondary recycled material is evaluated according to the degree of whitening caused by thermal crystallization at that time.
The degree of whitening due to thermal crystallization when heated is compared in terms of color such as whiteness and opacity, the speed of whitening, and the area of whitening when thermal crystallization is performed under specified conditions.If the color such as whiteness and opacity changes significantly compared to specified standards, if the speed of whitening is faster than specified standards, and/or if the area of whitening is large, the secondary recycled material is evaluated to contain a large amount of resin components that have deteriorated due to repeated recycling processes, and it can be determined that it is not suitable for manufacturing new recycled containers.
On the other hand, if the color such as whiteness and opacity due to thermal crystallization, the speed of whitening, and/or the area of whitening are comparable to the specified standards, the secondary recycled material is evaluated as not containing a large amount of resin components that have deteriorated due to repeated recycling processes, and it can be determined that the secondary recycled material is suitable for manufacturing new recycled containers.
Such a judgment can be made by visually observing the heated portion, but it is preferable to use a device having an identification function such as image processing to mechanically distinguish the heated portion from the viewpoint of stabilizing accuracy.

Here, the secondary recycled material for evaluating the degree of whitening due to thermal crystallization can be in any shape.
When evaluating a secondary recycled material by subjecting a plate-shaped injection-molded test piece made from a portion of the secondary recycled material to a thermal crystallization treatment, the half-crystallization time (t) of the crystallization rate of a resin material (virgin material) that has not been subjected to a recycling treatment may be determined by a differential scanning calorimeter (DSC), and the secondary recycled material may be evaluated based on the degree of whitening due to thermal crystallization by heating the material for a prescribed period of time within the range of 1/4 to 1/2 of the half-crystallization time (t).
Alternatively, if a sample preform is produced from the secondary recycled material, the shape and dimensions of at least its mouth being the same as those of a new recycled container produced using the mixed recycled material, then the mouth of the sample preform can be heated under the same conditions as those for providing the identification mark 6, and the degree of whitening due to thermal crystallization can be compared with the identification mark 6, making it possible to relatively easily evaluate the secondary recycled material. In this case, it is more preferable to perform a heat treatment on the peripheral edge of the neck ring provided at the mouth of the sample preform to evaluate the degree of whitening due to thermal crystallization, since whitening due to thermal crystallization progresses from the peripheral edge of the neck ring in the direction of the inner diameter, making it possible to easily evaluate the degree of whitening from the appearance.

Another example is a method for characterizing secondary recycled materials.
Specifically, in the case of polyester-based resins, when they are subjected to thermal history, the temperature-rising crystallization temperature (Tc1) tends to decrease, while at the same time the degree of crystallization attained tends to increase. Therefore, the temperature-rising crystallization temperature (Tc1) and the degree of crystallization are determined using a differential scanning calorimeter (DSC) to evaluate the secondary recycled material.

In this case, for a resin material (virgin material) that has not been subjected to a recycling process, the half-crystallization time (t) of the crystallization rate is obtained by a differential scanning calorimeter (DSC), and the material is heated for a predetermined time within a range of 1/4 to 1/2 of the half-crystallization time (t), and a predetermined standard is determined for the heating crystallization temperature (Tc1).
For example, if the heated crystallization temperature (Tc1) of the secondary recycled material is 10°C or more lower than the heated crystallization temperature (Tc1) of a resin material (virgin material) that has not undergone a recycling process, the secondary recycled material can be evaluated as containing a large amount of resin components that have deteriorated due to repeated recycling processes, and can be determined to be unsuitable for manufacturing new recycled containers.

Alternatively, when evaluating the characteristics, a value that is a unique guideline may be defined as a reference value and the evaluation may be performed.
The values used for the evaluation can be set based on various conditions, such as the composition of the resin material used, the molding conditions, and the physical properties desired for the recycled container. For example, if the heated crystallization temperature (Tc1) of the secondary recycled material is 145°C or lower, the secondary recycled material can be evaluated as containing a large amount of resin components that have deteriorated due to repeated recycling processes, and can be determined to be unsuitable for manufacturing new recycled containers.

Alternatively, if the crystallinity is 35% or more, or if the heating crystallization temperature (Tc1) is 145°C or less and the attained crystallinity exceeds 35%, the secondary recycled material is evaluated as containing a large amount of resin components that have deteriorated due to repeated recycling processes, and can be determined to be unsuitable for manufacturing new recycled containers.

The degree of crystallinity X [%] can be calculated from the following equation by cutting out a test piece from the measurement target site, measuring the density ρ (g/cm ³ ) of the test piece by a density gradient tube method, and using the density method.
X=(ρc(ρ-ρa))/(ρ(ρc-ρa))
ρa: amorphous density (g/cm ³ )
ρc: Crystal density (g/cm ³ )
When polyethylene terephthalate is used as the material resin, the degree of crystallinity X [%] can be calculated assuming ρc = 1.455 (g/cm ³ ) and ρa = 1.335 (g/cm ³ ).

In addition to such evaluation methods, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) of the secondary recycled material may be evaluated by gel permeation chromatography (GPC).
The values used for the evaluation can be set depending on various conditions, such as the composition of the resin material used and the physical properties desired for the recycled container. For example, if the weight average molecular weight (Mw) is 43,000 or less, or if the weight average molecular weight (Mw) and number average molecular weight (Mn) values obtained by gel permeation chromatography are equivalent to or higher than those of recycled materials that have not undergone recycling processes, but the molecular weight distribution (Mw/Mn) value is Mw/Mn = 2.9 or more, the secondary recycled material can be evaluated as containing a large amount of resin components that have deteriorated due to repeated recycling processes, and can be determined to be unsuitable for manufacturing new recycled containers.

The process of determining whether such secondary recycled materials can be reused is preferably carried out continuously within a series of processes in the "bottle-to-bottle" recycling cycle, and after the non-recycled containers and recycled containers are visually or spectroscopically separated and recovered using the identification mark 6, the recycled containers are cleaned and crushed, or crushed and washed to turn them into crushed flakes, and the crushed flakes are then accumulated in time segments at regular time intervals, and the suitability of the secondary recycled materials for reuse is determined for each lot number after numbering.
In this case, the shorter the time interval for collecting the time-divided crushed flakes, the higher the accuracy of the material quality of the separated and recovered secondary recycled materials will be. However, there are no specific requirements regarding the collection time, and it should be set arbitrarily depending on the size, processing equipment, processing capacity, and working conditions of the secondary recycled material processing facility.

The crushed flakes accumulated during this time period are automatically sampled for each lot, and a judgment is made according to the evaluation criteria described above as to whether or not they are suitable for reuse as secondary recycled material when producing new PET bottles (recycled PET bottles).
In addition, secondary recycled materials that are determined to be unsuitable for use as secondary recycled materials and are rejected can be reused by converting them into cascade uses such as flower pots and benches.

As described above, when recovered used containers are turned into raw materials and reused in the production of new recycled containers, a process of determining whether or not the secondary recycled materials are suitable for reuse can be further included. This makes it possible to appropriately eliminate secondary recycled materials that contain a large amount of resin components that have deteriorated due to repeated recycling processes when producing recycled containers, thereby enabling the stable production of containers made of recycled polyester resin in which deterioration of the resin's color and deterioration of the material properties are more effectively suppressed.
In addition, depending on the condition of the secondary recycled material, the mixing ratio with the primary recycled material can be appropriately changed to produce a mixed recycled material, so in this respect too, recycled containers can be stably produced in which deterioration of the resin's color and degradation of the material properties are more effectively suppressed.

The present invention has been described above with reference to preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

Reference Signs List 1 Container 2 Mouth 2b Neck ring 2c Neck section 3 Shoulder 4 Body 5 Bottom 6 Identification mark 10 Preform 20 Mouth 30 Body

Claims (5)

A method for recycling polyester-based resin containers in a circular manner, in which collected used polyester-based resin containers are recycled as raw materials and reused in the manufacture of new polyester-based resin containers, comprising the steps of:
A non-recycled container manufactured using virgin materials that have not been subjected to a recycling process or a recycled container manufactured using recycled materials that have been subjected to at least one recycling process is provided with an identification mark on at least one of a neck ring provided at the mouth or a neck portion of the mouth,
The collected used polyester resin containers are separated into non-recycled containers and recycled containers based on the presence or absence of the identification mark ,
The non-recycled containers are regenerated and then sorted into primary recycled materials and secondary recycled materials, which are obtained by regenerating the regenerated containers and then sorted into secondary recycled materials.
A circular recycling method for polyester-based resin containers, characterized in that either one or both of the primary recycled material and the secondary recycled material are reused to produce new polyester-based resin containers. 2. The method for recycling polyester resin containers according to claim 1 , wherein the neck ring or the neck portion is at least partially heated, and a portion whitened by thermal crystallization is used as the identification mark. 3. A circular recycling method for polyester resin containers as described in claim 1 or 2, which includes a step of determining whether the secondary recycled material can be reused, separating the secondary recycled material into reusable and difficult to reuse secondary recycled material, and excluding the difficult to reuse secondary recycled material from the recycling process. For the secondary recycled material, at least one value of the heating crystallization temperature (Tc1), the crystallinity, the weight average molecular weight (Mw), and the molecular weight distribution (Mw/Mn) is determined;
When the temperature-raised crystallization temperature (Tc1) is 10° C. or more lower than the temperature-raised crystallization temperature (Tc1) of a virgin material that has not been subjected to a regeneration treatment,
When the heating crystallization temperature (Tc1) is 145° C. or less,
When the crystallinity is 35% or more,
When the weight average molecular weight (Mw) is 43,000 or less,
When the molecular weight distribution (Mw/Mn) value is Mw/Mn=2.9 or more,
4. The method for recycling polyester-based resin containers according to claim 3, wherein if any of the above conditions is met, the secondary recycled material is evaluated as containing a large amount of resin components that have deteriorated due to repeated recycling processes, and is determined to be unsuitable for manufacturing new recycled containers. A method for producing a polyester-based resin container, comprising the steps of: making a raw material from collected used polyester-based resin containers, and reusing the raw material to produce a new polyester-based resin container, the method comprising the steps of:
A non-recycled container manufactured using virgin materials that have not been subjected to a recycling process or a recycled container manufactured using recycled materials that have been subjected to at least one recycling process is provided with an identification mark on at least one of a neck ring provided at the mouth or a neck portion of the mouth,
The collected used polyester resin containers are separated into non-recycled containers and recycled containers based on the presence or absence of the identification mark ,
The non-recycled containers are regenerated and then sorted into primary recycled materials and secondary recycled materials, which are obtained by regenerating the regenerated containers and then sorted into secondary recycled materials.
A method for producing a polyester-based resin container, characterized in that either one or both of the primary recycled material and the secondary recycled material are reused to produce the new polyester-based resin container.

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