Molded body, its manufacturing method and recycling method using same

Abstract

To provide a polyethylene terephthalate resin molding that has high decomposition efficiency and can be easily chemically recycled.SOLUTION: The present invention provides a molding of polyethylene terephthalate resin for use in producing monomers by the chemical decomposition of polyethylene terephthalate. When measured with a temperature-modulated differential scanning calorimeter, the molding has a glass transition temperature (Tg) and a crystallinity correlation parameter (ΔHTc1 / ΔHTm) satisfying Tg≥70°C and ΔHTc1 / ΔHTm≥0.5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molded article of polyethylene terephthalate resin, and more particularly to a molded article of polyethylene terephthalate resin used to produce a monomer by chemical decomposition of polyethylene terephthalate, a method for producing the same, and a method for recycling polyethylene terephthalate resin products using the same. [Background technology]

[0002] Plastic bottles are widely used in large quantities as containers for various liquids, such as drinking water, seasonings, cooking oil, alcoholic beverages, fuel, and detergents, due to their light weight and transparency, which allows the contents to be seen clearly, with polyethylene terephthalate bottles (hereinafter referred to as PET bottles) accounting for the majority of these.Used plastic bottles were traditionally disposed of by incineration or landfill, but in recent years, the Act on the Promotion of Separate Collection and Recycling of Containers and Packaging has come into effect, and along with the collection and recycling of PET bottles, the separate collection and recycling of used plastic containers and packaging has begun.

[0003] Methods for recycling these used plastics include material recycling, in which used plastics are remanufactured as raw materials for reuse; chemical recycling, in which used plastics are broken down to the monomer level for reuse; and thermal recycling, in which used plastics are reused as energy.

[0004] Taking used PET bottles as an example, chemical recycling methods have been developed and are beginning to be put into practical use. These methods involve chemically decomposing polyester, recovering oligomers or monomers, and then repolymerizing the polyester. Examples of known methods include washing used PET bottles, crushing them into flakes, adding methanol to decompose them into dimethyl terephthalate, and then hydrolyzing them again to obtain high-purity terephthalic acid (see, for example, Patent Document 1). Another method involves adding ethylene glycol to polyethylene terephthalate to decompose it into bis(2-hydroxyethyl) terephthalate, which is then melt-polycondensed to obtain polyethylene terephthalate polymer (see, for example, Patent Document 2). Another method involves reacting polyethylene terephthalate with water in a high-temperature, high-pressure state (called supercritical or subcritical) to hydrolyze it and obtain terephthalic acid (see, for example, Patent Document 3). Furthermore, a method has recently been proposed in which polyethylene terephthalate is hydrolyzed with an enzyme to obtain terephthalic acid (see, for example, Patent Document 4).

[0005] In addition, a method has been proposed for obtaining monomers by enzymatic hydrolysis of semi-crystalline polyester, in which the polymer is melted at a temperature above its melting point and then rapidly cooled below its crystallization temperature to make it amorphous, thereby improving decomposition efficiency (Patent Document 5). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-60369 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-169623 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-53801 [Patent Document 4] Special Publication No. 2016-505650 [Patent Document 5] U.S. Patent Publication No. 2019 / 218360 Summary of the Invention

[0007] As described above, chemical recycling methods in which used polyethylene terephthalate products such as bottles are decomposed to the monomer level for reuse can basically be considered methods for chemically decomposing polyethylene terephthalate. However, none of these methods have been found to have sufficient decomposition efficiency for practical use, and there is room for improvement in practical application. Therefore, a primary object of the present invention is to provide a polyethylene terephthalate resin molded product that is excellent in decomposition efficiency and easy to chemically recycle. Another object of the present invention is to provide a method for producing such a molded product and a method for recycling used polyethylene terephthalate resin products using such a molded product.

[0008] The above-mentioned Patent Document 5 discloses that the crystallinity of polyester affects the efficiency of hydrolysis, and furthermore, that decrystallization improves the decomposition efficiency. In an attempt to chemically recycle used polyethylene terephthalate resin products, the present inventors produced polyethylene terephthalate molded articles with low crystallinity and attempted hydrolysis, resulting in the surprising discovery that even if the crystallinity is too low, the decomposition efficiency decreases. Further investigation by the present inventors led to the discovery that the decomposition efficiency of polyethylene terephthalate can be further improved by producing a molded article having a crystallinity correlation parameter larger than a certain level (i.e., a crystallinity smaller than a certain level) and a glass transition temperature larger than a certain level. The present invention is based on this discovery. Specifically, the gist of the present invention is as follows.

[0009] [1] A molded article of polyethylene terephthalate resin used to produce a monomer by chemical decomposition of polyethylene terephthalate, The glass transition temperature (Tg) and crystallinity correlation parameter (ΔH) of the molded body measured using a temperature modulated differential scanning calorimeter Tc1 / ΔH Tm )but, Tg≧70℃ ΔH Tc1 / ΔH Tm ≧0.5 A molded body that satisfies the above. [2] The molded article according to [1], which has a film shape with a thickness of 10 to 350 μm. [3] Specific surface area is 7600mm 2 / g or more. [4] The molded article according to [1], wherein the polyethylene terephthalate resin is a recycled material obtained by reusing a product made of polyethylene terephthalate. [5] The molded article according to [4], wherein the polyethylene terephthalate resin has an intrinsic viscosity (IV) of 1.4 or less. [6] The molded article according to [1], wherein the chemical decomposition is carried out by an enzyme. [7] A method for producing the molded article according to [1], comprising withdrawing polyethylene terephthalate resin from a molten state at a draft ratio of 5 to 60 to obtain a molded article. [8] The method according to [7], wherein the polyethylene terephthalate resin is a recycled material obtained by reusing a product made of polyethylene terephthalate. [9] A method for recycling polyethylene terephthalate resin products, comprising: [1] A molded article is produced from a used polyethylene terephthalate resin product, Immersing the molded body in a medium containing an enzyme; producing a monomer or oligomer by chemical decomposition of the polyethylene terephthalate; A method comprising:

[0010] According to the present invention, it is possible to provide a polyethylene terephthalate resin molded article that is excellent in decomposition efficiency and easy to chemically recycle. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a graph showing the relationship between the glass transition temperature and the decomposition efficiency for each of the molded bodies of Examples 1 to 6 and Comparative Examples 1 to 4. [Figure 2] 1 is a graph showing the relationship between the crystallinity correlation parameter and the decomposition efficiency for each of the molded bodies of Examples 1 to 6 and Comparative Examples 1 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Molded body> The molded article according to the present invention is a molded article made of a polyethylene terephthalate resin, and the glass transition temperature (Tg) and the crystallinity correlation parameter (ΔH Tc1 / ΔH Tm )but, Tg≧70℃ ΔH Tc1 / ΔH Tm ≧0.5 In the present invention, excellent decomposition efficiency is realized by producing a polyethylene terephthalate resin molded article having a crystallinity correlation parameter of 0.5 or more (a certain amount of amorphous portion is present in the polyethylene terephthalate) and a glass transition temperature of 70°C or more (i.e., having a certain degree of crystal orientation). The reason for this is not clear, but is thought to be as follows.

[0013] That is, polyethylene terephthalate, known as a semi-crystalline polymer, is known to have crystalline and amorphous portions in the solid state, but from the viewpoint of hydrolysis efficiency, a low degree of crystallization is preferable. On the other hand, when attempting to obtain a resin molded product with a low degree of crystallinity, there is a limit to how much the surface area of ​​the molded product can be increased. Therefore, it is believed that by producing a molded product with a glass transition temperature above a certain value (i.e., a molded product that has been stretched to a certain extent), the surface area and the degree of crystallinity can be balanced, thereby maximizing the hydrolysis efficiency.

[0014] It is known that polyethylene terephthalate (hereinafter simply referred to as PET) can be rapidly cooled from a molten state to obtain a substantially amorphous PET resin, and the glass transition temperature of such amorphous PET resin is approximately 68°C. It is also known that PET undergoes orientation crystallization and increases in crystallinity through stretching or other treatments, and that the glass transition temperature of stretched PET film increases to approximately 78°C. In the present invention, a molded product is obtained that has a glass transition temperature of 70°C or higher. From the viewpoint of increasing the surface area and improving decomposition efficiency, the glass transition temperature is preferably 73°C or higher.

[0015] In the present invention, the glass transition temperature refers to the extrapolated glass transition onset temperature obtained as the inflection point of a melting endothermic curve measured using a temperature-modulated differential scanning calorimeter (DSC) under the following conditions: A method for obtaining a molded product having a glass transition temperature of 70°C or higher will be described later.

[0016] <Measurement conditions> Atmosphere: Nitrogen atmosphere ·Measurement temperature range: 0~150℃ Heating rate: 3°C / min Temperature modulation mode: ±0.48°C / 60 seconds (heat only mode) Sample weight: 3 mg

[0017] The molded article of the present invention has a crystallinity correlation parameter of 0.5 or more. A higher crystallinity correlation parameter promotes the hydrolysis of PET, improving the decomposition efficiency, and the preferred range of this parameter is 0.5 to 0.7. While a higher crystallinity correlation parameter is preferable from the viewpoint of hydrolysis efficiency, if the crystallinity correlation parameter is too high, it becomes difficult to obtain a molded article having the above-mentioned glass transition temperature of 70°C or more.

[0018] In the present invention, the crystallinity correlation parameter is the crystallization enthalpy (ΔH Tc1 ) and enthalpy of fusion of crystals (ΔHTm This value is negatively correlated with the degree of crystallinity measured by a density gradient method or the like. Crystallinity correlation parameter (X) = ΔH Tc1 / ΔH Tm

[0019] From the viewpoint of the hydrolysis efficiency of PET, the molded article of the present invention is preferably in the form of a film. In the case of a film-shaped molded article, its thickness is preferably 10 to 350 μm, more preferably 50 to 200 μm. From the viewpoint of the specific surface area, it can be said that a smaller film thickness is preferable, but in order to efficiently obtain a thin film, it is necessary to increase the draft ratio when forming the film or to perform a stretching treatment after film formation, and ΔH Tc1 / ΔH Tm It becomes difficult to obtain a molded product having a value of 0.5 or more.

[0020] In addition, when the molded product is in the form of a film, its specific surface area is 7600 to 160,000 mm from the viewpoint of the hydrolysis efficiency of PET. 2 / g, and 7600 to 31000 mm 2 It is thought that the larger the specific surface area of ​​the molded product, the more accelerated the hydrolysis of PET becomes. However, in order to obtain a molded product with a large specific surface area, it is necessary to increase the draft ratio during film formation or to perform a stretching treatment after film formation, and ΔH Tc1 / ΔH Tm It becomes difficult to obtain a molded product having a value of 0.5 or more.

[0021] Furthermore, the intrinsic viscosity (IV) of PET is preferably 1.4 or less. A lower intrinsic viscosity means a lower molecular weight, allowing the depolymerization reaction to proceed to the monomer or oligomer level in a shorter time. On the other hand, if the intrinsic viscosity is too low, molding may be difficult when the PET is cooled from a molten state to form a molded article. Furthermore, if the intrinsic viscosity of PET is too low, crystallization may occur easily during melt molding, and the crystallinity correlation parameter of the resulting molded article may be less than 0.5.

[0022] The PET that constitutes the molded product is obtained by polycondensation of two main constituent monomers, ethylene glycol and terephthalic acid, but other monomers may also be copolymerized as diol or dicarboxylic acid components in addition to these two components.

[0023] Examples of dicarboxylic acid components that can be used as copolymerization components for PET include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, 2,5-furandicarboxylic acid, and ester derivatives thereof.

[0024] Examples of diol components that can be used as copolymerization components for PET include 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecanediethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, 5-methylol-5-ethyl-2-(1,1-dimethylethyl)-2-(2-methyl ... 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamantanediol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, pentaerythritol, diethylene glycol, triethylene glycol, and bis-β-hydroxyethyl terephthalate (BHET).

[0025] Although the molded article of the present invention is made of PET resin, it may contain resin components other than PET, or other components such as additives. For example, one or more of various additives such as plasticizers, light stabilizers, antioxidants, ultraviolet absorbers, flame retardants, colorants, pigments, fillers, release agents, antistatic agents, fragrances, foaming agents, antibacterial and antifungal agents may be blended into the molded article, as long as they do not impair moldability when obtaining the molded article as a material for manufacturing the molded article, or inhibit chemical decomposition of PET.

[0026] <Method of manufacturing molded body> The molded article of the present invention can be obtained by feeding PET resin into an extruder and melting it at a temperature of 265°C to 295°C, passing it through a filter or gear pump to remove foreign matter and equalize the extrusion rate, and then discharging the molten resin from a T-die onto a casting drum or cooling drum to cool the resin.

[0027] To obtain a molded article with a glass transition temperature of 70°C or higher, it is preferable to take up the molten resin on a casting drum during film formation so that the draft ratio is in the range of 5 to 60. The draft ratio is expressed as the take-up speed (V) / exit speed (V0), and the higher the draft ratio, the more oriented crystallization progresses, resulting in a higher glass transition temperature of the resulting molded article. The extrusion speed (V0) is expressed by the following formula: Discharge outlet velocity (V0) = Discharge volume (W) / density (ρ) / cross-sectional area of ​​discharge outlet (S)

[0028] The obtained molded article may then be stretched as needed. For example, when the draft ratio during film formation is small, the stretching conditions can be adjusted so that the glass transition temperature of the obtained molded article is 70°C or higher and the crystallinity correlation parameter is 0.5 or higher.

[0029] The stretching treatment may be uniaxial or biaxial. For example, from the viewpoint of productivity and flatness, sequential biaxial stretching treatment may be performed in the longitudinal direction, the width direction, and the longitudinal direction. The stretching ratio during the stretching treatment is adjusted in relation to the above-mentioned draft ratio. Generally, the higher the stretching ratio, the more oriented crystallization progresses, so that the glass transition temperature increases and the crystallinity correlation parameter decreases.

[0030] Furthermore, considering chemical recycling, it is preferable that the PET resin used to obtain molded products be recycled. The recycled material may be petroleum-derived PET resin, plant-derived PET resin, or a mixture of the two. Examples of plant-derived PET resins include PET resins using diethylene glycol derived from bioethanol as a diol component. For example, recovered used PET bottles can be sorted, crushed, and washed to remove contaminants and foreign matter, resulting in flakes. PET bottles are typically manufactured using PET resin with an IV value of approximately 0.8. However, when flakes obtained from used PET bottles are used as the raw material for PET resin, the molded products obtained by remelting them have a lower IV value than the original PET due to hydrolysis of the PET during melt molding. Therefore, using such recycled materials as raw materials for molded products allows for the production of molded products with a desirable intrinsic viscosity (IV = 1.4 or less), resulting in molded products with even better decomposition efficiency.

[0031] <Recycling method> In the present invention, by using the molded article described above, it becomes possible to efficiently recycle PET resin products. For example, a molded article is produced from a used PET resin product as described above, and the obtained molded article is chemically decomposed by a conventionally known method, whereby the monomers or oligomers constituting the PET can be obtained from the used PET resin product. By polymerizing the obtained monomers or oligomers, a PET resin product can be produced again from the used PET resin product.

[0032] As an example of chemical recycling of PET resin products, flakes obtained by crushing used PET bottles are remelted to produce the molded product of the present invention, and the molded product is then immersed in a solvent such as methanol or ethylene glycol, or in a medium containing an enzyme, whereby polyethylene terephthalate is depolymerized to produce terephthalic acid.

[0033] PET hydrolysis can be carried out using, for example, a raw material composition containing a molded article, a microorganism capable of expressing and excreting a decomposing enzyme, water, etc. A buffer may be added to the raw material composition to stabilize the pH. The pH of the raw material composition is preferably 5 to 11 from the viewpoint of enzyme activity.

[0034] The depolymerization treatment time is preferably 1 to 24 hours, more preferably 4 to 16 hours.

[0035] To isolate the monomer from the recovered active ingredient, the monomer (terephthalic acid) may be extracted with an organic solvent in which the monomer dissolves, and the monomer constituting the polyester may be isolated from the extracted monomer solution by distillation, crystallization, etc. Alternatively, the monomer solution may be subjected to crystallization or distillation as is. Alternatively, the monomer solution may be subjected to ion exchange treatment or the like, followed by extraction, distillation, crystallization, etc.

[0036] In the above-mentioned chemical recycling, the use of a medium containing an enzyme for depolymerization eliminates the need for solvent recovery equipment and the like, compared with the use of a solvent such as methanol or ethylene glycol, and therefore allows chemical recycling to be performed more efficiently and at lower cost. [Example]

[0037] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0038] <Production of Molded Product> Used PET bottles were crushed and washed to remove contaminants and foreign matter, and then turned into flakes. The flakes were then remelted in an extruder and processed into pellets. The resulting pellets were fed into an extruder, and the molten resin was extruded onto a casting drum adjusted to 20°C by varying the discharge rate and take-up speed to form a film. The film obtained by the casting method was further heated to 100°C and subjected to simultaneous biaxial equal-stretching processing. Ten types of molded articles were obtained using two film-forming methods: Examples 1 to 6 and Comparative Examples 1 to 4. The thicknesses of the obtained molded articles were as shown in Table 1 below.

[0039] The IV value of each molded product was measured using a relative viscometer (Viscotec Y501C, manufactured by Malvern Panalytical) at a temperature of 25°C. The sample was dissolved in a phenol:tetrachloroethane (1:1) solvent to prepare a solution. The measurement result showed that the IV value of each molded product was 0.75. The weight-average molecular weight of each molded product was measured using a high-speed GPC device (HLC-8320GPC, manufactured by Tosoh Corporation). The sample was a solution dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Chloroform was used as the mobile phase, and the column used was a TSKgel SuperHM-H column manufactured by Tosoh Corporation, with measurements being carried out at 40°C. TSKgel standard polystyrene manufactured by Tosoh Corporation was used as the molecular weight standard. As a result of the measurement, the weight-average molecular weight of each molded product was 45,000.

[0040] <Measurement of crystallinity correlation parameters> Approximately 3 mg of each molded product was placed in an aluminum pan (TA Instruments, TZero aluminum pan) and subjected to measurement using a temperature-modulated differential scanning calorimeter (TA Instruments, DSC2500). The measurement conditions were a temperature rise rate of 3°C / min, and temperature modulation conditions were heat-only mode at ±0.48°C / 60 seconds. Data analysis was performed using TA Instruments' analysis software "TRIOS." From the total heat flow profile obtained from the temperature modulation heating measurement, the crystallization enthalpy (ΔH Tc1 ) and enthalpy of fusion of crystals (ΔH Tm ) was calculated. The calculation range wasTc1 is set appropriately within the range of 145°C or less depending on the peak shape, and ΔH Tm was fixed at 210 to 270°C. The obtained ΔH Tc1 and ΔH Tm The crystallinity correlation parameter (X) was calculated from the following formula. Crystallinity correlation parameter (X) = ΔH Tc1 / ΔH Tm The crystallinity correlation parameter (X) of each of the obtained molded bodies was as shown in Table 1 below.

[0041] <Measurement of glass transition temperature> For each molded product, a reversing heat flow profile was obtained by temperature-modulated heating measurement in the same manner as described above, and the extrapolated glass transition onset temperature obtained as the inflection point of the obtained profile curve was taken as the glass transition temperature (Tg). More specifically, using the above analysis software, the calculation range was set to 60°C as the analysis start temperature and the analysis end temperature according to the profile shape, and TgOnset analysis was performed to calculate the temperature. The glass transition temperature (Tg) of each of the obtained molded bodies is shown in Table 1 below.

[0042] <Hydrolysis of molded products> Each of the obtained molded articles was cut into a disk shape with a diameter of 14 mm to prepare a sample, and each sample was immersed in a buffer solution containing the enzyme for 24 hours to hydrolyze the PET. The total weight of the molded article before immersion in the buffer solution containing the enzyme (W b The decomposition efficiency (D) was calculated from the following formula using the weight (Wa) of the molded product after immersion and drying. Decomposition efficiency (D) = (W b -W a ) / W b ×100

[0043] The relationship between the glass transition temperature and the decomposition efficiency of each of the molded products of Examples 1 to 5 and Comparative Examples 1 to 4 is shown in Figure 1. The relationship between the crystallinity correlation parameter and the decomposition efficiency of each of the molded products is shown in Figure 2.

[0044] [Table 1]

[0045] As is clear from the evaluation results in Figures 1 and 2 and Table 1, the molded articles (Examples 1 to 6) having a glass transition temperature of 70°C or higher and a crystallinity correlation parameter of 0.5 or higher have excellent PET decomposition efficiency. On the other hand, even though the crystallinity correlation parameter is 0.5 or more, the molded product (Comparative Example 1) with a small draft ratio and a glass transition temperature of less than 70°C has a lower PET decomposition efficiency than the molded products of Examples 1 to 6. Furthermore, it is clear that molded articles (Comparative Examples 2 to 4) having a crystallinity correlation parameter of less than 0.5, even if they have a glass transition temperature of 70°C or higher, have lower PET decomposition efficiency than the molded articles of Examples 1 to 6.

Claims

1. A molded article of a polyethylene terephthalate resin used to produce a monomer by chemical decomposition of polyethylene terephthalate, The glass transition temperature (Tg) and crystallinity correlation parameter (ΔH) of the molded body are measured using a temperature modulated differential scanning calorimeter. Ｔｃ１ / ΔH Ｔｍ )but, Tg≧70°C ΔH Ｔｃ１ / ΔH Ｔｍ ≧0.5 (In the formula, ΔH Tc1 and ΔH Tm respectively represent the temperature-rising crystallization enthalpy (ΔH Tc1 ) and the crystalline melting enthalpy (ΔH Tm ) obtained from a melting endothermic curve measured under the following conditions using a temperature-modulated differential scanning calorimeter (DSC). <Measurement conditions> Atmosphere: Nitrogen atmosphere ・Measurement temperature range: 0 to 150℃ Temperature increase rate: 3°C / min Temperature modulation mode: ±0.48°C / 60 seconds (heat only mode) Sample weight: 3 mg A molded body that satisfies the above.

2. The molded article according to claim 1, which has a film form with a thickness of 10 to 350 μm.

3. Specific surface area is 7600 mm ２ The molded article according to claim 2, wherein the molecular weight is 1 / g or more.

4. 2. The molded article according to claim 1, wherein the polyethylene terephthalate resin is a recycled material obtained by reusing a product made of polyethylene terephthalate.

5. The molded article according to claim 4, wherein the polyethylene terephthalate resin has an intrinsic viscosity (IV) of 1.4 or less.

6. The molded article according to claim 1 , wherein the chemical decomposition is carried out by an enzyme.

7. A method for producing the molded article according to claim 1, comprising withdrawing polyethylene terephthalate resin from a molten state at a draft ratio of 5 to 60 to obtain the molded article.

8. The method according to claim 7, wherein the polyethylene terephthalate resin is a recycled material obtained by reusing a product made of polyethylene terephthalate.

9. A method for recycling polyethylene terephthalate resin products, comprising: A molding according to claim 1 is produced from a used polyethylene terephthalate resin product, Immersing the molded body in a medium containing an enzyme; producing a monomer or oligomer by chemical decomposition of the polyethylene terephthalate; A method comprising:

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