Recycling method and manufacturing method for polyester resin containers

Abstract

To resolve a problem caused in recycling circulation on a bottle-to-bottle solution that manufactures a new polyester-based resin container by re-forming a collected used polyester-based resin container into a raw material and by re-using thereof.SOLUTION: There is provided a circulation-type recycling method of a polyester-based resin container, the method uses for production of a new polyester resin container by re-forming a collected used polyester-based resin container into a raw material and by re-using thereof. The method comprises: separating a non-regenerated container manufactured using a virgin material that is not regenerated from the collected used container and a regenerated container manufactured using a recycled material that is obtained by regeneration processing at least once or more; classifying the separated material into a primary recycling material made from recycling and processing non-regenerated containers and a secondary recycling material made by regenerating the regenerated container; and manufacturing a new container by re-using one of or both of the primary recycling material and the secondary recycling material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a circulatory recycling method for polyester-based resin containers in which collected used polyester-based resin containers are recycled as raw materials and reused in the manufacture of new polyester-based resin containers, and to a method for manufacturing polyester-based resin containers suitable for such recycling. [Background technology]

[0002] Conventionally, polyester resin containers, which are made by producing a cylindrical preform with a bottom using a synthetic resin such as polyethylene terephthalate and then molding this preform into a bottle shape by stretch blow molding or the like, have been used in a wide range of fields as containers for various beverages, seasonings, etc. 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.

[0003] 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 a vacuum, and the flakes are then supplied in a molten state through a filter to an injection molding machine to injection mold preforms. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-514728 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 once or more. When PET bottles are repeatedly reused to produce PET bottles in this way, foreign matter remaining in the recycled materials is mixed in, and the recycled materials deteriorate due to the repeated heat history in the pelletizing process of the recycled materials and the PET bottle manufacturing process, causing the 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 can 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.

[0006] To address these issues, studies have been conducted on mixing recycled materials with resin materials that have not been recycled (virgin materials) to prevent the deterioration of the resin's color and 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 mix 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 mixed with colorants are then limited in the uses for which they can be reused.

[0007] Therefore, the inventors have conducted extensive research to solve the above-mentioned problems in the "bottle-to-bottle" recycling cycle in which collected used polyester-based resin containers are turned into raw materials and reused to manufacture new polyester-based resin containers, and as a result, have completed the present invention. [Means for solving the problem]

[0008] The method for recycling polyester-based resin containers according to the present invention is a method for recycling polyester-based resin containers in a circular manner, which comprises converting collected used polyester-based resin containers into raw materials and reusing them in the manufacture of new polyester-based resin containers, and 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, From the collected used polyester resin containers, The presence or absence of the identification mark determines whether Non-recyclable containers and The above The method involves separating the non-recycled containers from the recycled containers, separately sorting them into primary recycled materials obtained by recycling the non-recycled containers into raw materials, and secondary recycled materials obtained by recycling the recycled containers into raw materials, and reusing either or both of the primary recycled materials and the secondary recycled materials to manufacture the new polyester-based resin containers.

[0009] The method for producing a polyester-based resin container according to the present invention is a method for producing a polyester-based resin container, which comprises converting collected used polyester-based resin containers into raw materials and reusing the raw materials to produce new polyester-based resin containers, and 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, From the collected used polyester resin containers, The presence or absence of the identification mark determines whether Non-recyclable containers and The above The method involves separating the non-recycled containers from the recycled containers, separately sorting them into primary recycled materials obtained by recycling the non-recycled containers into raw materials, and secondary recycled materials obtained by recycling the recycled containers into raw materials, and reusing either or both of the primary recycled materials and the secondary recycled materials to manufacture the new polyester-based resin containers. Effect of the Invention

[0010] According to the present invention, in a recycling cycle in which collected used polyester-based resin containers are turned into raw materials and reused to manufacture new polyester-based resin containers, it is possible to stably produce recycled polyester-based resin containers in which deterioration of the color and degradation of the material properties of the recycled materials that are repeatedly reused are suppressed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an outline of a polyester-based resin container according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a perspective view showing an outline of a preform according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory view showing another example of a polyester-based resin container according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0013] 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 material 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.

[0014] In addition, as described below, this embodiment can include a process for determining whether or not the secondary recycled material is suitable for reuse. 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 is removed from the recycling process, making it possible to more stably produce recycled PET bottles made from 100% recycled material while more effectively suppressing deterioration of color and material properties in the "bottle-to-bottle" recycling cycle.

[0015] [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.

[0016] 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.

[0017] The mouth 2 is a cylindrical portion that serves as an outlet for pouring the content liquid, 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 cylindrical neck portion 2c of roughly the same diameter that hangs down 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.

[0018] Here, the up-down, left-right and length-width directions of the container 1 are defined when the container is held upright with the mouth part 2 side facing up. Similarly, the up-down, left-right and length-width directions of the preform 10, which will be described later, are defined when the preform is held upright with the mouth part 20 side facing up.

[0019] In addition, the container 1 shown in FIG. 1 has a bottom 5 formed in a so-called petaloid shape so as to be suitable for use with carbonated beverages as the contents, but there are also containers with bottoms 5 of other shapes suitable for use with non-carbonated beverages, various seasonings, etc.

[0020] In this embodiment, all containers generally called PET bottles, such as the container 1 shown in FIG. 1, can be subject to recycling.

[0021] Such a container 1 can be manufactured by preparing a preform 10 using a thermoplastic resin and molding it into a cylindrical shape with a bottom by injection molding, compression molding, or the like, and then molding this preform 10 into a predetermined container shape by biaxial stretch blow molding, or the like.

[0022] 2 shows an example of a preform 10 to be blow molded into a container 1, the preform 10 being 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 a portion that will become the mouth 2 of the container 1 without being stretched by blow molding and will generally maintain 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 characters as those given to the container 1. The portion below the neck ring 2b of the mouth 20 of the preform 10 will become the neck portion 2c of the container 1.

[0023] As the thermoplastic resin used, as is indicated by the name PET bottle, conventionally, thermoplastic polyester resins such as polyethylene terephthalate have been preferably used, but in general, the present invention can be applied to any recyclable polyester resin, regardless of whether it is an aromatic polyester or an aliphatic polyester.

[0024] 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 increased biomass content by using ethylene glycol derived from plant-derived bioethanol as a diol component. Naturally, the polyester-based resins with ethylene glycol derived from plant-derived bioethanol as a diol component and the polyester-based resins with ethylene glycol derived from petroleum-based fossil fuel as a diol component 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 increased biomass content are also subject to recycling.

[0025] Therefore, when repeating the "bottle-to-bottle" recycling cycle, since petroleum-based fossil fuel-derived polyester resins and plant-produced polyester resins can be used without distinction as they are 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-produced polyester resins.

[0026] For containers made from polyester resins with ethylene glycol as a diol component, which is made from plant-derived bioethanol, the presence of biomass polyester can be verified by measuring carbon-14 with an accelerator mass spectrometer (AMS). The composition ratio of biomass polyester can also be calculated from the radiation count per minute (CPM) intensity.

[0027] [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.

[0028] In addition, used containers 1 are generally collected in a state where their volume has been reduced by being crushed or the like, but since the container 1 is difficult to crush all the way to the mouth 2, 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.

[0029] In view of these factors, 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 in many cases will not be crushed during collection and will not be hidden by a cap or cap band, so that the identification mark 6 can be easily recognized from the appearance of the collected container 1.

[0030] The identification mark 6 is not particularly limited as long as it is provided in a form that allows the container 1 to be visually identified, but from the viewpoint of recycling, it is preferable that the identification mark 6 be in a form that allows the container 1 to be identified without using a coloring agent. For example, by at least partially heating the neck ring 2b or the neck portion 2c and whitening the area by thermal crystallization, the identification mark 6 can be attached without using a coloring agent. 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.

[0031] Although such identification marks 6 can be used to manually separate non-recyclable containers from recyclable containers, it is preferable, as this is more efficient, to use a device equipped 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.

[0032] 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.

[0033] To provide a whitened area by thermal crystallization at the mouth 2 of the container 1, the area to be thermally crystallized can be heated at a temperature, for example, equal to the crystallization temperature Tc of typical polyethylene terephthalate ±5°C for 20 to 150 seconds to provide the whitened area by thermal crystallization.

[0034] To provide the cutout portion 61 in the neck ring 2b of the container 1, when molding the preform 10, a protrusion of a desired shape can be provided at a position corresponding to the cutout portion 61 in the neck ring 2b of the molding die.

[0035] The method of separating PET bottles collected from the market into non-recyclable 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 in the community or society as a whole. Therefore, whether to provide the identification mark 6 on a non-recyclable or recycled container should be selected taking into consideration the overall consumer awareness, the establishment of social systems, and the industrial convenience of a separation system (device). However, since non-recyclable 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-recyclable containers.

[0036] [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. The use of secondary recycled materials that contain large amounts of deteriorated resin components is also undesirable 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.

[0037] In view of this, the present embodiment may further include a step of determining whether or not the secondary recycled material is suitable for reuse.

[0038] One example is a method for determining whether or not secondary recycled materials can be reused by utilizing the property that the crystallization temperature Tc of a material decreases with repeated regeneration processing. 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. 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 there is a significant change in color such as whiteness and opacity 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 it 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.

[0039] 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 process, the crystallization rate half-time (t) of the resin material (virgin material) that has not been subjected to the recycling process can be determined using a differential scanning calorimeter (DSC), and the secondary recycled material can be evaluated based on the degree of whitening associated with thermal crystallization by heating the material for a specified period of time within the range of 1 / 4 to 1 / 2 of the half-time (t). Alternatively, if a sample preform is produced from secondary recycled materials, the shape and dimensions of at least its mouth being the same as those of a new recycled container produced using the mixed recycled materials, then the mouth of the sample preform can be heated under the same conditions as those used to provide 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.

[0040] 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-raised crystallization temperature (Tc1) tends to decrease while at the same time the degree of crystallization achieved tends to increase. Therefore, a differential scanning calorimeter (DSC) is used to determine the temperature-raised crystallization temperature (Tc1) and degree of crystallinity to evaluate secondary recycled materials.

[0041] 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 specified time within the range of 1 / 4 to 1 / 2 of the half-crystallization time (t), and a specified standard is determined for the heating crystallization temperature (Tc1). For example, if the heated crystallization temperature (Tc1) of a 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.

[0042] 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 in 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.

[0043] Alternatively, if the crystallinity is 35% or higher, or if the heating crystallization temperature (Tc1) is 145°C or lower and the achieved 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.

[0044] The degree of crystallinity X [%] is determined by cutting a test piece from the measurement target area and measuring the density ρ (g / cm 3 ) and calculate it by the density method using the following formula. 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 resin material, ρc=1.455(g / cm 3 ), ρa = 1.335 (g / cm 3 ) and the degree of crystallinity X [%] can be calculated.

[0045] 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 in 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 been recycled, 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.

[0046] 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-recyclable containers and recycled containers are visually or spectroscopically separated and recovered using the identification mark 6, the recycled containers are washed and crushed, or crushed and washed to turn them into crushed flakes, and the crushed flakes are then accumulated in time segments at regular intervals, and the suitability of the secondary recycled materials for reuse is preferably 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.

[0047] 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.

[0048] 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.

[0049] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0050] 1 container 2 Mouth 2b Neck ring 2c lower neck 3 Shoulder 4. Torso 5 Bottom 6 Identification Mark 10 Preform 20 Mouth 30 Torso

Claims

1. 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 into primary recycled materials and the regenerated containers are regenerated 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 the new polyester-based resin container.

2. 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. 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.

4. 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.

5. 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 into primary recycled materials and the regenerated containers are regenerated 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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