Method for producing thermoplastic polyester elastomer

Abstract

The invention provides a manufacturing method of a thermoplastic polyester elastomer, which comprises the following steps of: providing a polyester recycling material which comprises polyethylene terephthalate; carrying out a first depolymerization step, namely mixing the polyester recycling material with a polyethylene terephthalate oligomer, and carrying out extrusion depolymerization, so as to at least obtain a polyethylene terephthalate polymer; and performing a polymerization step including adding the long-chain polyalkyl diol to perform a polymerization reaction to at least obtain the thermoplastic polyester elastomer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a thermoplastic polyester elastomer, and more particularly to a method for manufacturing a thermoplastic polyester elastomer including extrusion depolymerization. Background Technology

[0002] Polyester products are widely used in daily life, thus generating a large amount of polyester waste. Current methods for recycling polyester waste often involve extruding and alcoholyzing large quantities of diols. However, diols are easily vaporized at high temperatures, making the recycling process hazardous and the reaction difficult to control. Therefore, how to effectively recycle and / or treat polyester waste is a current research topic. Summary of the Invention

[0003] This invention provides a method for manufacturing thermoplastic polyester elastomers, which can effectively recycle polyester waste and reduce recycling costs.

[0004] A method for manufacturing a thermoplastic polyester elastomer according to the present invention includes the following steps: providing a polyester recycled material, the polyester recycled material including polyethylene terephthalate (PET); performing a first depolymerization step, which includes mixing the polyester recycled material with a polyethylene terephthalate oligomer for extrusion depolymerization to obtain at least a polyethylene terephthalate polymer; and performing a polymerization step, which includes adding a long-chain polyalkyl diol for polymerization to obtain at least a thermoplastic polyester elastomer (TPEE).

[0005] In one embodiment of the present invention, the above-mentioned polyethylene terephthalate oligomer includes bis(2-HydroxyEthyl Terephthalate) (BHET), polyethylene terephthalate dimer, polyethylene terephthalate trimer, mono(2-hydroxyethyl) terephthalic acid (MHET), or a combination thereof.

[0006] In one embodiment of the present invention, the above-mentioned long-chain polyalkyl diol includes polyethylene glycol (PEG), polytetramethylene ether glycol (PTMEG), or a combination thereof.

[0007] In one embodiment of the present invention, the amount of the long-chain polyalkyl diol added in the polymerization step is 20% to 60% by weight of the total weight of the reactants in the polymerization reaction.

[0008] In one embodiment of the present invention, the above manufacturing method further includes: performing a second depolymerization step, which includes chemically depolymerizing polyethylene terephthalate polymer by mixing it with a depolymerization solution to obtain at least diethyl terephthalate monomer.

[0009] In one embodiment of the present invention, the above-described manufacturing method further includes: performing a transesterification step, which includes mixing bis-hydroxypropyl terephthalate monomer with an aliphatic diol to carry out a transesterification reaction to obtain a product. The product includes bis-hydroxypropyl terephthalate (BHPT), bis-hydroxybutyl terephthalate (BHBT), or a combination thereof.

[0010] In one embodiment of the present invention, the above-mentioned aliphatic diol includes a diol having 3 to 10 carbon atoms.

[0011] In one embodiment of the present invention, the above polymerization step includes mixing the product with a long-chain polyalkyl diol to carry out a polymerization reaction to obtain at least a thermoplastic polyester elastomer.

[0012] In one embodiment of the present invention, the above polymerization step includes mixing polyethylene terephthalate polymer with long-chain polyalkyl diol to carry out a polymerization reaction to at least obtain a thermoplastic polyester elastomer.

[0013] In one embodiment of the present invention, the first depolymerization step, the second depolymerization step and / or the polymerization step further include the addition of a catalyst.

[0014] Based on the above, the method for manufacturing the thermoplastic polyester elastomer of the present invention includes mixing recycled polyester with polyethylene terephthalate oligomer, followed by a depolymerization step and a polymerization reaction step to obtain the thermoplastic polyester elastomer, wherein the depolymerization step involves extrusion depolymerization. This allows for the effective recycling of waste polyester, reduces polyester recycling costs, and consequently reduces environmental burden, achieving environmental protection and a circular economy effect.

[0015] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described in detail below. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for manufacturing a thermoplastic polyester elastomer according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] S100, S105, S110, S120, S130, S140: Steps Detailed Implementation

[0019] The following are detailed embodiments describing the content of this invention. The implementation details presented in these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Anyone skilled in the art can modify or vary these implementation details according to the needs of actual implementation. Furthermore, descriptions of well-known apparatus, methods, and materials may be omitted to avoid obscuring the description of the various principles of this invention.

[0020] A range may be expressed herein as from “about” a specific value to “about” another specific value, or it may be directly expressed as a specific value and / or to another specific value. In expressing the range, another embodiment includes from that specific value and / or to another specific value. Similarly, when a value is expressed as an approximation by using the antecedent “about,” it will be understood that the specific value forms another embodiment. It will be further understood that each endpoint of a range may be obviously related to or unrelated to another endpoint.

[0021] In this document, non-limiting terms (such as: may, can, for example, or other similar terms) are non-essential or optional implementations, inclusions, additions, or existences.

[0022] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that terms (such as those defined in commonly used dictionaries) shall be interpreted as having the same meaning as in the relevant technical context and shall not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0023] Figure 1 This is a schematic flowchart illustrating a method for manufacturing a thermoplastic polyester elastomer according to an embodiment of the present invention. Figure 1 As shown, the process of manufacturing thermoplastic polyester elastomers may include the following steps.

[0024] Step S100: Provide recycled polyester.

[0025] Step S105: Provide polyethylene terephthalate (PET) oligomer.

[0026] Step S110: First depolymerization step: Perform push-out depolymerization.

[0027] Step S120: Second depolymerization step: Chemical depolymerization is carried out by adding depolymerization solution.

[0028] Step S130: Transesterification step: Transesterification reaction is carried out by adding an aliphatic diol.

[0029] Step S140: Polymerization step: A polymerization reaction is carried out by adding a long-chain polyalkyl diol to obtain at least a thermoplastic polyester elastomer.

[0030] Specifically, the method for manufacturing thermoplastic polyester elastomers may sequentially include a first depolymerization step, a second depolymerization step, a transesterification step, and a polymerization step. In another embodiment, the method for manufacturing thermoplastic polyester elastomers may only sequentially include a first depolymerization step and a polymerization step. The steps will be described in detail below.

[0031] [Provides recycled polyester]

[0032] Polyester recycling includes polyethylene terephthalate (PET). For example, sources of polyester recycling may include textiles, packaging materials (such as PET bottle flakes), or other suitable PET products. Polyester recycling may also include dyes or other impurities.

[0033] In some embodiments, the recycled polyester material may be pretreated (i.e., treated before subsequent processing; it is still essentially a recycled material). Pretreatment may include, for example, removing objects from the recycled material (e.g., clips, fasteners, ornaments, zippers, tags, and / or other obviously non-polyester-containing items), performing preliminary cleaning of the recycled material (e.g., washing stains, removing impurities, etc.), decolorization, and other suitable procedures. For example, decolorization may be achieved by immersing the recycled polyester material in an extraction solvent to extract impurities, thus achieving a decolorization effect. However, the invention is not limited to this; any method that removes impurities from the recycled polyester material is acceptable. In some embodiments, the extraction solvent may be selected from at least one of the group consisting of toluene, xylene, acetic acid, propylene glycol methyl ether, and ethylene glycol.

[0034] In this document, the term "polyester" includes polymers commonly referred to as polyesters, particularly aromatic polyesters, and specifically polyesters derived from purified terephthalic acid (PTA) and ethylene glycol (EG) (i.e., polyethylene terephthalate (PET)). Furthermore, polyester as used herein may also include, for example, polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, or combinations thereof.

[0035] [First step of depolymerization]

[0036] The first depolymerization step involves extruding the polyester recycled material with polyethylene terephthalate oligomers to obtain at least polyethylene terephthalate (PET) polymers. For example, the polyester recycled material or recovered polyester can be fed into an extruder for extrusion to depolymerize the polyester therein by reactive extrusion.

[0037] Extruders may include screw extruders, such as commercially available single screw extruders (SSE), twin screw extruders (TSE), or other suitable extruders, but the present invention is not limited thereto. The construction and / or operation of the aforementioned commercially available screw extruders may be similar to those known to those skilled in the art, and therefore will not be described in detail herein.

[0038] Polyethylene terephthalate oligomers can be fed into an extruder to improve the polyester depolymerization rate and / or quality within the extruder. In this embodiment, the polyethylene terephthalate oligomer may include bis(hydroxyethyl) terephthalate, polyethylene terephthalate dimer, polyethylene terephthalate trimer, mono(2-hydroxyethyl) terephthalic acid, combinations thereof, or other suitable polyethylene terephthalate oligomers, preferably bis(hydroxyethyl) terephthalate or polyethylene terephthalate dimer. In the first depolymerization step, the amount of polyethylene terephthalate oligomer added may be from about 5% to about 20% by weight, preferably from about 10% to about 15% by weight, of the total weight of the extruded depolymerization reactants.

[0039] In this embodiment, feeding polyethylene terephthalate (PET) oligomers into the extruder is safer and / or simpler for the reprocessing steps and / or the corresponding equipment compared to feeding ethylene glycol (EG) into the extruder. For example, feeding PET oligomers into the extruder does not require providing additional back pressure or reducing the back pressure of the extruder compared to feeding ethylene glycol (EG).

[0040] In the first depolymerization step, a catalyst may be added. For example, recycled polyester, polyethylene terephthalate oligomer, and a catalyst can be mixed and then extruded for depolymerization. The catalyst can be fed into the extruder to increase the polyester depolymerization rate within the extruder. There are no particular limitations on the catalyst; an appropriate catalyst can be selected as needed. For example, the catalyst may include chelated titanium catalysts, organozinc (e.g., zinc acetate), organocobalt (e.g., cobalt acetate), organotitanium (e.g., alkoxide titanium salts), organoantimony (e.g., antimony acetate), organoaluminum (e.g., aluminum formate, aluminum acetate, aluminum propionate, etc.), or other suitable catalysts. A single catalyst can be used, or multiple catalysts can be used in combination. In this embodiment, the catalyst is preferably organotitanium or organocobalt. When the depolymerization reaction is carried out in an environment containing a catalyst, the reaction rate can be increased. In the first depolymerization step, the amount of catalyst added may be from about 0.2% to about 8% by weight of the total weight of the extruded depolymerized reactants, preferably from about 0.5% to about 5% by weight.

[0041] In one embodiment, at least one feeder (e.g., a side feeder) may be attached to the extruder. The feeder may be a loss-in-weight feeder equipped with a loss-in-weight meter. Such feeders are also common commercially available devices and / or optional accessories. That is, the aforementioned components (e.g., recycled polyester, polyethylene terephthalate oligomers, and / or catalysts) may be mixed before feeding; or, they may be fed into the extruder via different feeders and mixed within the extruder. The mixture within the extruder can essentially undergo a corresponding homogeneous reaction. This may reduce the corresponding mass transfer bottleneck.

[0042] The extruder may also have a heating zone. Here, after the recycled polyester is fed into the extruder, the polyester-containing mixture inside the extruder can be correspondingly extruded and heated to depolymerize via a hot-pressing reaction, and then extruded or pressed. The heating temperature of the heating zone can be from about 200°C to about 280°C, preferably from about 220°C to about 260°C.

[0043] For example, the depolymerization time of polyester extrusion by reactive extrusion can be from about 1 minute to about 10 minutes, preferably from about 2 minutes to about 5 minutes. The depolymerization time of polyester extrusion by heated reactive extrusion can be from about 1 minute to about 10 minutes, preferably from about 2 minutes to about 5 minutes; wherein the heating temperature can be from about 200°C to about 280°C, preferably from about 220°C to about 260°C. If the aforementioned depolymerization time is too short (e.g., less than 1 minute) and / or the heating temperature is too low (e.g., less than 200°C), the depolymerization efficiency may be reduced, thus reducing the efficiency of subsequent processing. If the aforementioned depolymerization time is too long (e.g., more than 10 minutes) and / or the heating temperature is too high (e.g., more than 280°C), the proportion of other byproducts or impurities may be too high, thus reducing the efficiency of subsequent processing.

[0044] In this embodiment, the first depolymerization step depolymerizes most of the polyester in the recycled material into polyethylene terephthalate (PET) polymers, and may further include oligomers. For example, the PET polymer may be a polymerization of about 2 to 5 PET monomers. The number of monomers corresponding to the PET polymer can be deduced by an appropriate method (e.g., by molecular weight calculation).

[0045] [Second disintegration step]

[0046] The second depolymerization step is performed after the first depolymerization step. The second depolymerization step may include chemical depolymerization by mixing the polyethylene terephthalate polymer with a depolymerization solution to obtain at least diethyl terephthalate (BHET) monomer. For example, the polyethylene terephthalate polymer obtained in the first depolymerization step and the depolymerization solution may be added to a depolymerization tank for chemical depolymerization.

[0047] There are no particular limitations on the depolymerization solution; an appropriate solution can be selected based on requirements. Essentially, the depolymerization solution further breaks down the chains of polyethylene terephthalate (PET) polymers, thereby achieving a further depolymerization effect. For example, it may be possible to obtain polyester compositions with shorter molecular chains (such as PET oligomers) and ester monomers composed of one diacid unit and two diol units (such as diethyl terephthalate (BHET) monomer). The average molecular weight of the mixture after chemical depolymerization is generally lower than the average molecular weight of the mixture obtained in the first depolymerization step (which is mostly PET polymer).

[0048] For example, the depolymerization solution may include alcohols such as methanol, ethanol, ethylene glycol (EG), diethylene glycol, combinations thereof, or other suitable alcohols, preferably ethylene glycol. Ethylene glycol is preferred as a depolymerization solution because it is a reactive monomer used in the production of virgin PET chips. In the second depolymerization step, the amount of depolymerization solution added may be from about 30% to about 80% by weight of the total weight of the reactants in the chemical depolymerization reaction, preferably from about 40% to about 70% by weight. If the aforementioned amount of ethylene glycol added is too low (e.g., less than 30% by weight), it may reduce the depolymerization efficiency, thereby reducing the efficiency of subsequent processing. If the aforementioned amount of ethylene glycol added is too high (e.g., greater than 80% by weight), although it may increase the depolymerization efficiency, it will also generate excessive diethylene glycol, thus affecting product quality.

[0049] The second depolymerization step may further include the addition of a catalyst. For example, the polyethylene terephthalate polymer, the depolymerization solution, and the catalyst can be mixed and then subjected to chemical depolymerization. There are no particular limitations on the catalyst, and an appropriate catalyst can be selected according to requirements. The catalyst added in the second depolymerization step may be the same as or different from the catalyst added in the first depolymerization step. In the second depolymerization step, the amount of catalyst added may be from about 0.3% to about 8% by weight of the total weight of the reactants in the chemical depolymerization reaction, preferably from about 1% to about 5% by weight.

[0050] During the chemical depolymerization reaction, a heating step may be appropriately performed. Generally, heating can accelerate the chemical reaction. For example, the polyethylene terephthalate polymer obtained from the first depolymerization step can be added to a depolymerization tank and subjected to alcoholysis at a temperature of about 190°C to about 260°C for about 1 hour to 6 hours, preferably at a temperature of about 205°C to about 245°C for about 3 hours to 5 hours. If the aforementioned depolymerization time is too short (e.g., less than 1 hour) and / or the heating temperature is too low (e.g., less than 190°C), the depolymerization efficiency may be reduced, thereby reducing the subsequent transesterification efficiency. If the aforementioned depolymerization time is too long (e.g., more than 6 hours) and / or the heating temperature is too high (e.g., more than 260°C), most of the polyethylene terephthalate polymer may have been depolymerized into diethyl terephthalate (BHET) monomers. Although the proportion of the material to be depolymerized may be slightly increased, it will require more time or cost (e.g., heat energy), thus increasing the cost.

[0051] [Transesterification Step]

[0052] The transesterification step may include mixing a bis(hydroxyethyl) terephthalate (BHET) monomer with an aliphatic diol to carry out a transesterification reaction to obtain a product. The product may include bis(hydroxypropyl) terephthalate (BHPT), bis(hydroxybutyl) terephthalate (BHBT), or a combination thereof.

[0053] Aliphatic diols may include diols with 3 to 10 carbon atoms, preferably diols with 3 to 5 carbon atoms, and more preferably 1,2-propanediol, 1,3-propanediol, or 1,4-butanediol. For example, aliphatic diols may include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, or other suitable aliphatic diols. In the transesterification step, the molar ratio of bis(hydroxyethyl) terephthalate (BHET) monomer to the aliphatic diol may be from 1:1 to 1:5, preferably from 1:2 to 1:4.

[0054] For example, the reaction time for the transesterification reaction can be from about 1 hour to about 6 hours, preferably from about 3 hours to about 5 hours; the reaction temperature can be from about 210°C to about 260°C, preferably from about 220°C to about 250°C; and the reaction pressure can be from atmospheric pressure to about 3.5 kg / cm³. 2 The optimal value is approximately 1.0 kg / cm². 2 Approximately 3.0 kg / cm 2 .

[0055] The esterification rate of the transesterification reaction can be from about 90% to about 99.5%, preferably from about 95% to about 99.5%.

[0056] [Aggregation Steps]

[0057] The polymerization step includes adding a long-chain polyalkyl diol to carry out a polymerization reaction to at least obtain a thermoplastic polyester elastomer. The thermoplastic polyester elastomer may include soft segments and hard segments, wherein the soft segments are mainly composed of long-chain polyalkyl diols, and the hard segments are mainly composed of polybutylene terephthalate (PBT) obtained by polycondensation of dibutyl terephthalate (BHBT). In other embodiments, the hard segments of the thermoplastic polyester elastomer may be mainly composed of polytrimethylene terephthalate (PPT) obtained by polycondensation of dipropyl terephthalate (BHPT).

[0058] In this embodiment, the long-chain polyalkyl diol may include polyethylene glycol, polytetramethylene ether glycol, combinations thereof, or other suitable polyethylene terephthalate oligomers, preferably polyethylene glycol or polytetramethylene ether glycol. In the polymerization step, the amount of the long-chain polyalkyl diol added may be from about 20% to about 60% by weight of the total weight of the reactants in the polymerization reaction, preferably from about 25% to about 55% by weight.

[0059] In one embodiment, when the steps of the method for manufacturing a thermoplastic polyester elastomer sequentially include a first depolymerization step, a second depolymerization step, a transesterification step, and a polymerization step (hereinafter referred to as the first manufacturing method for brevity), the polymerization step may include mixing the product obtained in the transesterification step with a long-chain polyalkyl diol to perform a polymerization reaction to at least obtain a thermoplastic polyester elastomer. Based on the fact that the sum of the proportions of soft segments and hard segments in the thermoplastic polyester elastomer is 100%, the proportion of soft segments in the obtained thermoplastic polyester elastomer may be from about 20% to about 60%, preferably from about 25% to about 55%. In this embodiment, the amount of polyethylene terephthalate oligomer added may be from about 5% by weight to about 20% by weight, preferably from about 10% by weight to about 15% by weight, of the total weight of the reactants extruded and depolymerized in the first depolymerization step.

[0060] In another embodiment, when the steps of the method for manufacturing the thermoplastic polyester elastomer sequentially include a first depolymerization step and a polymerization step (hereinafter referred to as the second manufacturing method for simplicity), the polymerization step may include mixing the polyethylene terephthalate polymer obtained in the first depolymerization step with a long-chain polyalkyl diol to perform a polymerization reaction to at least obtain a thermoplastic polyester elastomer. Based on the fact that the sum of the proportions of soft segments and hard segments in the thermoplastic polyester elastomer is 100%, the proportion of soft segments in the obtained thermoplastic polyester elastomer may be from about 0% to about 20%, preferably from about 5% to about 15%. In this embodiment, the amount of polyethylene terephthalate oligomer added may be from about 3% by weight to about 15% by weight, preferably from about 5% by weight to about 10% by weight, of the total weight of the reactants extruded and depolymerized in the first depolymerization step.

[0061] The polymerization step may further include the addition of a catalyst. For example, the product obtained in the transesterification step, the long-chain polyalkyl diol, and the catalyst may be mixed and then subjected to a transesterification reaction, or the polyethylene terephthalate polymer obtained in the first depolymerization step, the long-chain polyalkyl diol, and the catalyst may be mixed and then subjected to a transesterification reaction. There are no particular limitations on the catalyst, and an appropriate catalyst may be selected as needed. The catalyst added in the polymerization step may be the same as or different from the catalyst added in the first depolymerization step and / or the second depolymerization step. In the polymerization step, the amount of catalyst added (e.g., the amount of titanium added) may be from about 25 ppm to about 150 ppm by weight of the total weight of the reactants in the polymerization reaction, preferably from about 50 ppm to about 100 ppm.

[0062] The polymerization step may further include the addition of antioxidants. There are no particular limitations on the antioxidants; appropriate antioxidants can be selected based on requirements. For example, antioxidants may include pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, phenyl tris(2,4-di-tert-butyl)phosphite, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, or other suitable antioxidants. Antioxidants may be used alone or in combination. When the polymerization reaction is carried out in an environment containing antioxidants, the degradation of the obtained thermoplastic polyester elastomer due to oxidation can be prevented. In the polymerization step, the amount of antioxidant added may be from about 500 ppm to about 1500 ppm by weight of the total weight of the reactants in the polymerization reaction, preferably from about 750 ppm to about 1250 ppm.

[0063] The aforementioned polymerization step can be referred to as the main polymerization reaction. In other embodiments, a prepolymerization reaction may be carried out before the main polymerization reaction. For example, the reaction time of the main polymerization reaction may be from about 1 hour to about 3 hours, preferably from about 1 hour to about 2 hours; the reaction temperature may be from about 200°C to about 300°C, preferably from about 240°C to about 280°C; and the reaction pressure may be from 0 to about 10 tors, preferably from about 0 to about 0.5 tors. This allows the thermoplastic polyester elastomer to achieve a target intrinsic viscosity (IV), for example, from about 0.6 dL / g to about 2.0 dL / g. The prepolymerization reaction may include heating the reactants to 200°C to 300°C and reducing the pressure from atmospheric pressure to 20 tors over 1 hour.

[0064] Then, a single-screw granulator or a twin-screw granulator can be used to granulate the thermoplastic polyester elastomer obtained in the polymerization step to form thermoplastic polyester elastomer granules for convenient subsequent applications.

[0065] In this embodiment, the thermoplastic polyester elastomer produced by the manufacturing method can have good hue quality. Hue quality can be represented by the L value, a value, and b value of the CIE Lab color space commonly used in the industry. The L value represents lightness, the a value represents the green-red value, and the b value represents the blue-yellow value. For example, the L value of the thermoplastic polyester elastomer can be greater than 65, preferably greater than 70; the b value can be less than 12, preferably less than 10.

[0066] Examples of methods for manufacturing thermoplastic polyester elastomers

[0067] The following describes Examples 1 to 3 and Comparative Example 1 of the method for manufacturing thermoplastic polyester elastomers:

[0068] Example 1

[0069] 180g of recycled PET bottle flakes and 26.5g of diethyl terephthalate (BHET) are fed into an extruder for extrusion to perform the first depolymerization step. In the first depolymerization step, the polyester extrusion depolymerization is carried out by a heated reactive extrusion method at a heating temperature of approximately 245°C and a depolymerization time of approximately 2.5 minutes.

[0070] Then, 95.7 g of ethylene glycol (EG) and 0.4 g of catalyst AQ5000 (product name, purchased from Perricone AG) were added to the product obtained after the first depolymerization step to carry out chemical depolymerization. The second depolymerization step was an alcoholysis reaction carried out at a temperature of about 210°C for about 191 minutes.

[0071] Next, 337 g of 1,4-butanediol (1,4-BDO) was added to the product obtained after the alcoholysis reaction to carry out a transesterification reaction. The transesterification reaction took approximately 217 minutes, at a temperature of approximately 240°C, and at atmospheric pressure.

[0072] Then, the product obtained after the transesterification reaction was transferred to a polymerization tank. 70.655g of PTMEG1000 (product name FAS PTMG; molecular weight: 1000; purchased from Formosa Plastics Asahi Elastic Fiber Co., Ltd.), 70.655g of PTMEG2000 (product name FAS PTMG; molecular weight: 2000; purchased from Formosa Plastics Asahi Elastic Fiber Co., Ltd.), 94.2g of PTMEG3000 (product name FAS PTMG; molecular weight: 3000; purchased from Formosa Plastics Asahi Elastic Fiber Co., Ltd.), and 0.45g of antioxidant I-1010 (product name...) were added. 1010 (purchased from BASF), 0.113g sodium acetate (as an auxiliary catalyst) (purchased from Kawasaki Chemical Co., Ltd. (Air Water Performance Chemical)) and 0.45g catalyst AQ5000 (product name, purchased from Perricone) (as a polymerization catalyst) were added to the polymerization tank and mixed with the product obtained after the transesterification reaction.

[0073] Subsequently, a prepolymerization reaction was carried out for 60 minutes in a reaction tank at a temperature of 275°C and at a reaction pressure that decreased from atmospheric pressure to 20 Torr over 1 hour. Then, a primary polymerization reaction was carried out for 35 minutes at a reaction temperature of 255°C and a reaction pressure of less than 1.5 Torr to obtain the thermoplastic polyester elastomer of Example 1.

[0074] Example 2

[0075] Example 2 is similar to the manufacturing method of Example 1, except that: 0.2 g of zinc acetate (as a catalyst) is added in the first depolymerization step; the reaction time of the alcoholysis reaction is changed to about 176 minutes in the second depolymerization step; the reaction time of the transesterification reaction is changed to about 230 minutes in the transesterification step; and the reaction time of the main polymerization reaction is changed to about 21 minutes in the polymerization step.

[0076] Example 3

[0077] Example 3 is similar to the manufacturing method of Example 1, except that: in the first depolymerization step, the amount of recycled PET bottle flakes is changed to 160g, the amount of diethyl terephthalate (BHET) is changed to 53.0g, and the heating temperature for polyester extrusion depolymerization is changed to about 240°C; in the second depolymerization step, the amount of ethylene glycol (EG) is changed to 85.1g, and the reaction time of the alcoholysis reaction is changed to about 193 minutes; in the transesterification step, the reaction time of the transesterification reaction is changed to about 227 minutes; and in the polymerization step, the reaction time of the main polymerization reaction is changed to about 41 minutes.

[0078] Comparative Example 1

[0079] Comparative Example 1 is similar to the manufacturing method of Example 1, except that: in the first depolymerization step, the amount of recycled PET bottle flakes is changed to 200g, diethyl terephthalate (BHET) is not added, and the heating temperature for polyester extrusion depolymerization is changed to about 250°C; in the second depolymerization step, the reaction time of the alcoholysis reaction is changed to about 225 minutes; in the transesterification step, the reaction time of the transesterification reaction is changed to about 215 minutes; and in the polymerization step, the reaction time of the main polymerization reaction is changed to about 21 minutes.

[0080] The thermoplastic polyester elastomers prepared in each experimental example were evaluated using the following evaluation methods, and the results are shown in Table 1.

[0081] [Table 1]

[0082]

[0083] <Evaluation Method>

[0084] Intrinsic viscosity: The viscosity of thermoplastic polyester elastomers was tested according to ASTM D4603.

[0085] Hue quality: The hue quality (L value, a value, b value) of thermoplastic polyester elastomers is tested according to ASTM E1164.

[0086] <Evaluation Results>

[0087] As shown in Table 1, the thermoplastic polyester elastomers produced in Examples 1-3, whose manufacturing method includes a first depolymerization step of mixing recycled polyester with polyethylene terephthalate oligomers and then extruding and depolymerizing, exhibit good viscosity and color. In contrast, the thermoplastic polyester elastomer produced in Comparative Example 1, whose manufacturing method does not include a first depolymerization step with polyethylene terephthalate oligomers, has poor color quality.

[0088] In summary, the method for manufacturing thermoplastic polyester elastomers of the present invention involves a depolymerization step (extrusion depolymerization) and a polymerization step (mixing recycled polyester with polyethylene terephthalate oligomers) to obtain the thermoplastic polyester elastomer. This effectively recycles and reuses waste polyester, thereby reducing the environmental burden and achieving the goals of environmental protection and a circular economy. Furthermore, the method for manufacturing thermoplastic polyester elastomers further includes a depolymerization step (chemical depolymerization) and a transesterification step, which allows for a wider range of soft segment proportions in the resulting thermoplastic polyester elastomer, thus broadening its applicability.

[0089] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for manufacturing a thermoplastic polyester elastomer, comprising: Provided polyester recyclables, including polyethylene terephthalate (PET). Performing the first depolymerization step includes mixing the polyester recyclable with polyethylene terephthalate oligomer and extruding depolymerization to obtain at least polyethylene terephthalate polymer; as well as The polymerization step includes adding a long-chain polyalkyl diol to carry out a polymerization reaction to at least obtain a thermoplastic polyester elastomer.

2. The method for manufacturing thermoplastic polyester elastomer according to claim 1, wherein the polyethylene terephthalate oligomer includes bis(hydroxyethyl) terephthalate, polyethylene terephthalate dimer, polyethylene terephthalate trimer, mono(2-hydroxyethyl) terephthalic acid, or a combination thereof.

3. The method for manufacturing thermoplastic polyester elastomer according to claim 1, wherein the long-chain polyalkyl diol includes polyethylene glycol, polytetramethylene ether glycol, or a combination thereof.

4. The method for manufacturing thermoplastic polyester elastomer according to claim 1, wherein the amount of the long-chain polyalkyl diol added in the polymerization step accounts for 20% to 60% by weight of the total weight of the reactants in the polymerization reaction.

5. The method for manufacturing the thermoplastic polyester elastomer according to claim 1, further comprising: Performing a second depolymerization step includes chemically depolymerizing the polyethylene terephthalate polymer by mixing it with a depolymerization solution to obtain at least diethyl terephthalate monomer.

6. The method for manufacturing the thermoplastic polyester elastomer according to claim 5, further comprising: The transesterification step involves mixing the diethyl terephthalate monomer with an aliphatic diol to carry out a transesterification reaction to obtain the product. The product includes dihydroxypropyl terephthalate, dihydroxybutyl terephthalate, or a combination thereof.

7. The method for manufacturing the thermoplastic polyester elastomer according to claim 6, wherein the aliphatic diol comprises a diol having 3 to 10 carbon atoms.

8. The method for manufacturing a thermoplastic polyester elastomer according to claim 6, wherein the polymerization step comprises mixing the product with the long-chain polyalkyl diol to carry out the polymerization reaction to at least obtain the thermoplastic polyester elastomer.

9. The method for manufacturing a thermoplastic polyester elastomer according to claim 1, wherein the polymerization step comprises mixing the polyethylene terephthalate polymer with the long-chain polyalkyl diol to carry out a polymerization reaction to obtain at least the thermoplastic polyester elastomer.

10. A method for manufacturing a thermoplastic polyester elastomer according to any one of claims 1 to 9, wherein the first depolymerization step, the second depolymerization step and / or the polymerization step further include the addition of a catalyst.

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