Disposal method for recyclate containing polyester

Abstract

To provide a disposal method for a recyclable material containing polyester (recyclate).SOLUTION: A disposal method for recyclate comprises: providing a recyclable material containing polyester; performing a first depolymerization step, comprising mixing the recyclable material and oligo-bis(2-hydroxyethyl) terephthalate (o-BHET) for reaction and extrusion depolymerization to at least obtain or produce poly-bis(2-hydroxyethyl) terephthalate (p-BHET); and performing a second depolymerization step, comprising mixing the p-BHET and a depolymerization solution for chemically depolymerization to at least obtain or produce monomer-bis(2-hydroxyethyl) terephthalate (m-BHET).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for treating recyclates, and more particularly to a method for treating recyclates containing polyester. [Background technology]

[0002] Polyester fiber is a commonly found fabric in the market and in daily life. For example, polyester fiber can be woven with nylon fiber and spandex fiber to be made into all kinds of fabrics such as clothes, shirts, covers, bags, quilts, hats, skirts, mattresses, trousers, socks, etc., by using conventional methods in the fabric and garment industries. With the recent awakening of environmental awareness, research is being conducted on recycling polyester in these fabrics and / or treating polyester waste. Summary of the Invention [Problem to be solved by the invention]

[0003] Accordingly, the present invention provides a method for treating polyester-containing recyclate. [Means for solving the problem]

[0004] In one embodiment, the present invention provides a method for treating recyclates, the method including providing a recycled material containing polyester; performing a first depolymerization step including mixing the renewable material with oligo-bis(2-hydroxyethyl) terephthalate (о-BHET) for reaction and extrusion depolymerization to obtain or produce at least poly-bis(2-hydroxyethyl) terephthalate (p-BHET); and performing a second depolymerization step including mixing p-BHET with a depolymerization solution for chemical depolymerization to obtain or produce at least monomer Bis(2-HydroxyEthyl) Terephthalate (m-BHET). Effect of the Invention

[0005] Based on the above, the present invention can improve the overall recycling efficiency and / or recycling rate of polyester, which can further reduce the recycling cost. [Brief description of the drawings]

[0006] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, the drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0007] [Figure 1] FIG. 1 is a flow diagram of a method for treating polyester-containing recycle material according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, exemplary embodiments depicting specific details are set forth for purposes of explanation and not limitation in order to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to those skilled in the art having the benefit of the present invention that the present invention may be practiced in other embodiments that depart from the specific details described herein. Additionally, descriptions of well-known devices, methods, and materials are omitted so as not to obscure the description of the various principles of the present invention.

[0009] As used herein, non-limiting terms (e.g., about, substantially, essentially, essentially, capable, can, or other similar terms) refer to non-required or optional implementation, inclusion, addition, or presence.

[0010] A range may be expressed herein as from "about" one particular value to "about" another particular value, or may be linearly expressed as one particular value and / or another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation, by using "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are expressly related to, or independent of, the other endpoint.

[0011] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as the meaning in the common knowledge or commonly understood meaning in the technical field to which the present invention belongs. It should be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having a meaning consistent with the meaning in the relevant technical context, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0012] [Recycled material containing polyester] A recycled material containing polyester (also referred to as a recycler) is provided. In one embodiment, the recycled material containing polyester may be referred to as a polyester-containing recycler.

[0013] In one embodiment, the method for obtaining recycled materials includes collecting various types of recycled materials or waste containing polyester and performing corresponding classification according to the above-mentioned documents, colors, and / or purposes of the recycled materials. The above-mentioned recycled materials include, for example, clothes, shirts, covers, bags, quilts, hats, skirts, mattresses, pants, socks, but the present invention is not limited thereto. Generally, the label of a normal garment indicates the fiber composition used.

[0014] In one embodiment, the polyester-containing recycled material may be further pre-treated (i.e., prior to subsequent processing, while still essentially recycled material), which may include removing objects on the recycled material (e.g., clips, fasteners, trim, labels, and / or other objects that do not obviously contain polyester), pre-cleaning the recycled material (e.g., cleaning stains, removing impurities, etc., but this is not limited to this invention), using physical methods to reduce the recycled material to a single size (e.g., including but not limited to shearing, shredding, cutting, or slicing), and / or drying the recycled material.

[0015] In one embodiment, the method of obtaining recycled material may include, for example, directly purchasing the treated polyester-containing recycled material.

[0016] It should be noted that the term "polyester" as used herein includes polymers commonly referred to as polyesters, particularly aromatic polyesters, and in particular refers to polyesters derived from purified terephthalic acid (PTA) and ethylene glycol (EG) (i.e., polyethylene terephthalate (PET)).

[0017] In addition, the polyester herein may be, for example, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or a combination of the above materials. In an embodiment, the polyester is preferably polyethylene terephthalate, polytrimethylene terephthalate, or a combination thereof. In addition, copolymers may be used, which particularly refers to copolymers obtained using two or more dicarboxylic acids and / or two or more diol components.

[0018] In one embodiment, the dyes used in the fabric are mostly organic dyes. For example, azo dyes (e.g., monoazo dyes or disazo dyes) are commonly used to dye polyester. Organic dyes generally adhere better to polymers. It should be noted that the present invention does not limit the type of organic dye.

[0019] In one embodiment, the dyes used in the fabric do not contain inorganic dyes, since most inorganic dyes contain heavy metal elements that are prone to cause allergies and discomfort to the human body.

[0020] In one embodiment, the weight ratio of dye to the entire fabric is substantially less than 10% by weight, based on the total weight of the fabric.

[0021] In one embodiment, the weight ratio of polyester to the entire fabric is greater than or substantially equal to 90% by weight, based on the total weight of the fabric.

[0022] [Pretreatment of polyester-containing recyclates] In one embodiment, the appropriate size of the recycler may be selected by a suitable method for the subsequent regeneration step (e.g., sieving through a sieve or classification through an air classifier, but the invention is not limited thereto).

[0023] In one embodiment, the appropriate size of the recyclate may be determined or confirmed by any suitable method (eg, weighing method such as a balance).

[0024] In one embodiment, a weighing method for determining or confirming the proper size of a recycler may include, for example, using 2 grams as a unit, and if the particle count of the recycler is 50 or greater, it may be determined or confirmed as a properly sized recycler.

[0025] In one embodiment, the recyclate may be sized by physical methods (e.g., shearing, chopping, cutting, or cleaving, but the invention is not limited thereto) before proceeding to the subsequent regeneration step.

[0026] [Regeneration step of polyester-containing recyclate] Figure 1 is a flow diagram of a method for treating a polyester-containing recycle material according to one embodiment of the present invention. As shown in Figure 1, the process of the method for treating a polyester-containing recycle material may include the following steps:

[0027] Step S11: Providing a polyester-containing recycle or recycled polyester.

[0028] Step S12: Providing oligo-bis(2-hydroxyethyl)terephthalate (o-BHET).

[0029] Step S20: Carry out the first depolymerization step. The first step includes a process of mixing polyester-containing recycle or recycled polyester with o-BHET to react and extrude depolymerize.

[0030] Step S30: At least poly-bis(2-hydroxyethyl) terephthalate (p-BHET) is obtained or produced.

[0031] Step S40: Carry out the second depolymerization step The first stage includes a process of carrying out chemical depolymerization of poly-bis(2-hydroxyethyl)terephthalate (p-BHET).

[0032] Step S51: Monomer-bis(2-hydroxyethyl)terephthalate (m-BHET) is obtained or produced.

[0033] Step S52: Oligo-bis(2-hydroxyethyl)terephthalate (o-BHET) is obtained or produced.

[0034] In one embodiment, the o-BHET obtained or generated in step S52 may be further used for a subsequent step identical or similar to step S12.

[0035] Specifically, the process of the method for treating the polyester-containing recycler may include a first depolymerization step and a second depolymerization step in succession, the detailed description of which is as follows:

[0036] [First depolymerization step] By feeding the polyester-containing recycle or recycled polyester into an extruder for extrusion, the polyester therein is depolymerized by reaction during extrusion, thus the depolymerization may be referred to as reaction and extrusion depolymerization.

[0037] The extruder may be, for example, a commercially available single screw extruder (SSE), twin screw extruder (TSE), or other similar screw extruder, but the invention is not limited thereto, and in addition, the invention does not describe in detail the structure and / or operation of commercially available screw extruders.

[0038] In one embodiment, o-BHET may be fed to the extruder to improve the depolymerization and / or quality of the polyester fed to the extruder.

[0039] In one embodiment, the above-mentioned o-BHET may be, for example, a polymer of 2 to 5 bis(2-hydroxyethyl) terephthalate (BHET) monomers. The number of corresponding monomer units of o-BHET may be calculated or estimated by an appropriate method (for example, calculated or estimated from the corresponding molecular weight).

[0040] In one embodiment, BHET can be one of the raw materials for polyester (e.g., polyethylene terephthalate (PET)). Thus, the addition of BHET or its oligomers can have essentially no effect (e.g., side reactants and / or impurities) on polyester recycled from polyester-containing recyclates or can reduce side reactants and / or impurities.

[0041] In one embodiment, o-BHET may be obtained or generated from another or corresponding regeneration step.

[0042] In one embodiment, BHET or its oligomers may be obtained or produced from the esterification reaction of terephthalic acid (PTA) and ethylene glycol (EG).

[0043] In one embodiment, essentially no ethylene glycol (EG) is added or fed to the extruder during the process of depolymerizing the polyester by reaction during extrusion.

[0044] The boiling point of o-BHET is higher than that of BHET and EG (approximately 197 degrees Celsius or 387 degrees Fahrenheit). Thus, in one embodiment, feeding o-BHET to an extruder may be safer and / or simpler for equipment (e.g., extruder) compatible with a regenerative process (e.g., extrusion process) compared to feeding m-BHET or EG to an extruder. For example, feeding o-BHET to an extruder may be done without the need to provide additional back pressure or with reduced extruder back pressure compared to feeding m-BHET or EG.

[0045] In one embodiment, the boiling point of o-BHET may be greater than or equal to about 250 degrees Celsius or 482 degrees Fahrenheit.

[0046] In one embodiment, based on the total weight of the materials fed to the extruder, the weight ratio of o-BHET in the materials fed to the extruder is essentially about 5% by weight to 20% by weight, and preferably about 10% by weight to 15% by weight.

[0047] In one embodiment, in order to improve the depolymerization rate of the polyester fed to the extruder, a corresponding catalyst may be fed to the extruder.

[0048] In one embodiment, the catalyst described above may include an organometallic compound.

[0049] In one embodiment, the catalytic organometallic compound described above may include organozinc (e.g., zinc acetate), organocobalt (e.g., cobalt acetate), organotitanium (e.g., titanium alkoxide salts), organoantimony (e.g., antimony acetate), organoaluminum (e.g., aluminum formate, aluminum acetate, aluminum propionate, and other organic aluminum compounds), or combinations thereof.

[0050] In one embodiment, based on the total weight of the materials fed to the extruder, the weight ratio of the catalyst in the materials fed to the extruder is about 0.2% to 8% by weight, preferably about 0.5% to 5% by weight.

[0051] In one embodiment, based on the total weight of the polyester-containing recycle, o-BHET, and catalyst fed to the extruder, the weight ratio of o-BHET in the above-mentioned three materials fed to the extruder is essentially about 5% by weight to 20% by weight, and preferably about 10% by weight to 15% by weight.

[0052] In one embodiment, based on the total weight of the polyester-containing recycle, o-BHET, and catalyst fed to the extruder, the weight ratio of the catalyst in the above-mentioned three materials fed to the extruder is basically about 0.2 wt% to 8 wt%, preferably about 0.5 wt% to 5 wt%.

[0053] If the relative amount of o-BHET described above is too low (e.g., less than 5 wt%) and / or the relative amount of catalyst is too low (e.g., less than 0.2 wt%), the depolymerization efficiency and / or the amount of depolymerization may decrease, which may decrease the efficiency of subsequent treatment and / or decrease the final relative amount of regeneration.

[0054] If the relative amount of o-BHET is excessively high (e.g., more than 20 wt%), the depolymerization rate of the target depolymerized material may increase slightly, but the overall depolymerization amount may decrease, which may increase the recycling cost.

[0055] If the relative amount of the above-mentioned catalyst is too high (e.g., greater than 8 wt%), the depolymerization rate of the target depolymerized material may increase slightly, but more catalyst may be required, which may reduce the overall amount of depolymerization and / or conversely increase the difficulty of subsequent catalyst treatment (e.g., catalyst separation), which may increase recycling costs.

[0056] In one embodiment, at least one feeder (e.g., a side feeder) may be attached to the extruder. The aforementioned feeder may be a loss-in-weight feeder equipped with a weight loss meter. The aforementioned feeder may also be a common commercially available module and / or an optional accessory. In other words, the various materials (e.g., the recycler containing polyester, and further o-BHET and / or catalyst) may be mixed before feeding, or they may be fed to the extruder through different feeders and mixed in the extruder.

[0057] In one embodiment, the mixture in the extruder undergoes an essentially corresponding homogeneous reaction, thus reducing process or reaction bottlenecks caused by corresponding mass transfer.

[0058] In one embodiment, the extruder may have a heating zone. In this way, after the polyester-containing recycle is fed into the extruder, the polyester-containing mixture in the extruder may be correspondingly extruded and heated to be depolymerized through thermal extrusion or thermal pressure reaction, and then squeezed out or extruded. In one embodiment, the heating temperature of the heating zone is about 200-280°C, preferably about 220-260°C.

[0059] In one embodiment, the polyester depolymerization reaction time during extrusion (also referred to as the extrusion time) may be about 1 to 10 minutes, preferably about 2 to 5 minutes.

[0060] In one embodiment, the thermal polyester depolymerization reaction time during extrusion (also referred to as extrusion time) may be about 1 to 10 minutes, preferably about 2 to 5 minutes, and the heating temperature may be between about 200°C and 280°C, preferably about 220°C and 260°C.

[0061] If the above-mentioned extrusion time is too short (e.g., less than 1 minute) and / or if the heating temperature is too low (e.g., less than 200°C), the depolymerization efficiency and / or the relative depolymerization rate may decrease, which may result in a decrease in the efficiency of subsequent processing and / or a decrease in the final relative regeneration amount.

[0062] If the above-mentioned depolymerization time is too long (e.g., longer than 10 minutes) and / or if the heating temperature is too high (e.g., higher than 280°C), the relative proportion of side reaction products or impurities may increase, which may reduce the efficiency of subsequent processing and / or the final relative amount of regeneration may decrease.

[0063] In one embodiment, the first depolymerization step can depolymerize most of the polyester in the recycle material to poly-bis(2-hydroxyethyl) terephthalate (p-BHET). Compared to o-BHET, p-BHET contains more BHET monomer, but substantially insufficient p-BHET to form fibers or polymers suitable for suitable applications.

[0064] In one embodiment, the p-BHET described above is, for example, a polymer of about 10 to 100 BHET monomers (e.g., 10 to 100 BHET monomer units). The number of corresponding p-BHET monomer units may be calculated or estimated by an appropriate method (e.g., calculated or estimated from the corresponding molecular weight).

[0065] [Second depolymerization step] The first depolymerization step is followed by a second depolymerization step.

[0066] The second depolymerization step may include a chemical depolymerization process. For example, the p-BHET obtained in the first depolymerization step may be introduced into a depolymerization tank together with a depolymerization solution for chemical depolymerization.

[0067] The chemical depolymerization solution can essentially break the polymer chains of p-BHET, thus allowing further depolymerization. In this way, compounds with shorter polyester chains (e.g., o-BHET) and ester monomers consisting of dicarboxylic acid units and diols (e.g., m-BHET) can be obtained. In other words, the average molecular weight of the mixture after chemical depolymerization is essentially lower than that of the mixture (mostly p-BHET) obtained in the first depolymerization step.

[0068] The present invention does not limit the type of the depolymerization solution. For example, hydrolysis may be performed using water. For example, alcoholysis may be performed by using alcohol (e.g., methanol, ethanol, ethylene glycol, diethylene glycol, or a mixture thereof). In one embodiment, the depolymerization solution is preferably an alcohol. It is more preferably EG, because EG can serve as a reactive monomer to produce virgin PET chips.

[0069] In one embodiment, based on the total weight of reactants involved in the depolymerization reaction (e.g., p-BHET obtained in the first depolymerization step and ethylene glycol for the chemical depolymerization step), the weight ratio of EG is essentially about 30% by weight to 80% by weight, and preferably about 40% by weight to 70% by weight.

[0070] If the relative amount of ethylene glycol is too low (e.g., less than 30 wt%), the depolymerization efficiency and / or amount of depolymerization may decrease, which may decrease the efficiency of downstream processing and / or may decrease the final relative amount of regeneration.

[0071] If the relative amount of ethylene glycol is too high (e.g., greater than 80 wt%), it may require more ethylene glycol, even though it may only slightly increase the depolymerization rate of the target depolymerized material, and / or may conversely reduce the overall amount of depolymerization, thereby increasing recycling costs.

[0072] During the chemical depolymerization reaction, a suitable heating step may be carried out. An increase in temperature typically increases the rate of the chemical reaction. For example, after introducing p-BHET and ethylene glycol obtained in the first depolymerization step into the depolymerization tank, alcoholysis may be carried out at a temperature of 190° C. to 240° C. for about 0.5 to 5 hours. The alcoholysis is preferably carried out at a temperature of 200° C. to 230° C. for 1 to 3 hours.

[0073] When the above-mentioned chemical depolymerization time is too short (e.g., less than 0.5 hours) and / or when the heating temperature is too low (e.g., less than 190°C), the depolymerization efficiency and / or the amount of depolymerization may decrease, which may result in a decrease in the efficiency of subsequent treatment and / or a decrease in the final relative amount of regeneration.

[0074] If the above-mentioned chemical depolymerization time is too long (e.g., longer than 5 hours) and / or the heating temperature is too high (e.g., higher than 240° C.), the depolymerization rate increases slightly, but more time or cost (e.g., thermal energy) is required because most of p-BHET has been depolymerized to m-BHET.

[0075] Separation of the products of the above depolymerization step After carrying out the second depolymerization step, the depolymerization products may include compounds having shorter polyester chains (e.g., o-BHET) and ester monomers consisting of dicarboxylic acid units and diols (e.g., m-BHET). The ester monomers and compounds having shorter polyester chains may be separated by suitable purification methods (e.g., crystallization, activated carbon adsorption, filtration, and / or drying).

[0076] [Examples and Comparative Examples] EXAMPLES The following examples and comparative examples are provided to illustrate the present invention, but are not intended to limit the present invention.

[0077] <Example 1>

[0078] About 90 kilograms (kg) of polyester-containing recyclate (e.g., waste PET fabric, "PET" in Table 1) is provided. The polyester-containing recyclate described above is mixed with about 10 kg of o-BHET and about 0.3 kg of zinc acetate (which may be referred to as a catalyst), and then fed into a twin-screw extruder for extrusion and pre-depolymerization. The heating temperature of the extruder is about 260°C. The extruded p-BHET ("extruded product" in Table 1) is then entered into a stirred tank, and an additional about 400 kg of EG and about 0.2 kg of zinc acetate (which may be referred to as a catalyst) are added, and the reaction is continued at about 190°C to 200°C (e.g., about 195°C to 198°C) for about 180 minutes to depolymerize into a crude product. The crude product includes o-BHET and m-BHET.

[0079] After depolymerization, the crude product is cooled to about room temperature (e.g., 198→25°C), and o-BHET and m-BHET are crystallized and filtered. The filtered crystals are then mixed with hot water at 90°C. o-BHET is essentially insoluble and is filtered for reuse by extrusion and pre-depolymerization. m-BHET, which is essentially soluble in hot water at 90°C, is purified by removing impurities using activated carbon or other suitable adsorbents. The purified 90°C solution containing m-BHET is then cooled to about 5°C, and dissolved to crystallize and precipitate m-BHET, which, after filtration and drying, gives the corresponding m-BHET.

[0080] Finally, based on the weight of the raw polyester-containing recyclate, the weight ratio of the m-BHET product is about 80.6% by weight, i.e., the recycled rate of polyester is about 80.6% by weight.

[0081] In the above-mentioned method, the depolymerization reaction between the extrusion of the polyester-containing recyclate and o-BHET (i.e., the first depolymerization step, which may be called the preliminary depolymerization step) is a homogeneous reaction in a nearly molten state. In addition, after the above-mentioned preliminary depolymerization step, the extruded p-BHET is basically soluble in EG at about 190°C to 200°C (e.g., about 195°C to 198°C), so the chemical depolymerization process of p-BHET and EG (i.e., the second depolymerization step) is a liquid homogeneous reaction. The corresponding reactions under the corresponding homogeneous reaction can increase the overall total recycling efficiency and / or recycling rate of polyester.

[0082] <Example 2>, <Example 3>, <Example 4>

[0083] Examples 2, 3, and 4 were carried out in a similar manner to Example 1. The obvious differences are the ratio of the amount of о-BHET in the pre-depolymerization step, the ratio of the amount of zinc acetate in the corresponding depolymerization step ("ZnAc" in Table 1), the corresponding reaction temperature ("Temperature" in Table 1), and / or the corresponding reaction time ("Time" in Table 1).

[0084] The corresponding conditions / parameters and results for Examples 2, 3 and 4 are shown in Table 1.

[0085] [Table 1]

[0086] <Comparative Example 1>

[0087] About 100 kilograms (kg) of polyester-containing recyclate (e.g., waste PET fabric, "PET" in Table 2) is provided. The polyester-containing recyclate described above is fed into a stirred tank, and an additional about 400 kg of EG and about 0.5 kg of zinc acetate are added, and the reaction is continued at about 190°C to 200°C (e.g., about 195°C to 198°C) for about 180 minutes to depolymerize into a crude product, which includes o-BHET and m-BHET.

[0088] After depolymerization, the crude product is cooled to about room temperature (e.g., 198→25°C), and o-BHET and m-BHET are crystallized and filtered. The filtered crystals are then mixed with hot water at 90°C. o-BHET is essentially insoluble and is filtered. m-BHET, which is essentially soluble in hot water at 90°C, is purified by removing impurities using activated carbon or other suitable adsorbents. The purified 90°C solution containing m-BHET is then cooled to about 5°C, and m-BHET is dissolved to crystallize and precipitate, and the corresponding m-BHET is obtained after filtration and drying.

[0089] Finally, based on the weight of the raw polyester-containing recyclate, the weight ratio of the m-BHET product is about 67.4% by weight, i.e., the recycled rate of polyester is about 67.4% by weight.

[0090] In the above-mentioned method, it is difficult or even impossible for the polyester-containing recyclate to melt in EG at about 190°C to 200°C (e.g., about 195°C to 198°C). Therefore, the initial reaction state of the corresponding depolymerization reaction is basically a solid-liquid heterogeneous reaction. As a result, the overall recycling efficiency and / or recycling rate is reduced or decreased.

[0091] <Comparative Example 2>, <Comparative Example 3>, <Comparative Example 4>

[0092] Comparative Example 2, Comparative Example 3, and Comparative Example 4 were carried out in a similar manner to Comparative Example 1. The obvious differences are the ratio of the amount of zinc acetate in the corresponding depolymerization step ("ZnAc" in Table 2), the corresponding reaction temperature ("Temperature" in Table 2), and / or the corresponding reaction time ("Time" in Table 2).

[0093] [Table 2]

[0094] [Use of depolymerization products] From the ester monomer (e.g., m-BHET) consisting of a dicarboxylic acid unit and a diol obtained by the above-mentioned processing method, the corresponding recycled polyester (recycled PET, r-PET) can be obtained by a general synthesis method (e.g., esterification and / or polymerization reaction).

[0095] The shorter polyester chain compound (e.g., o-BHET) can be purified by a suitable method (e.g., crystallization, activated carbon adsorption, filtration, and / or drying) to remove impurities (e.g., dyes or their derivatives, salts, but not limited to them), and the purified shorter polyester chain compound can then be used in a subsequent regeneration step (e.g., the same as or similar to the first depolymerization step described above) of the method for treating polyester-containing recyclerate.

[0096] [Unpredictable effects] The process of the present invention includes the above-mentioned first depolymerization step (including the reaction during extrusion) for depolymerizing the polyester-containing recyclate to p-BHET, and the above-mentioned second depolymerization step (including the chemical depolymerization reaction) for depolymerizing the p-BHET to m-BHET. In this way, the overall recycling efficiency and / or recycling rate of polyester can be increased, which further reduces the recycling cost.

[0097] Compared with the direct treatment method (e.g., only chemical depolymerization as shown in the above-mentioned comparative example), the overall recycling efficiency and / or recycling rate of the polyester of the present invention is higher, and the recycling cost can be further reduced. For example, the treatment method of the recycler containing the polyester by only chemical depolymerization may require a longer depolymerization time, may require a larger amount of depolymerization solution, and / or may generate more impurities. The reason may be that the polyester chain length of the recycler is longer, and / or the long-chain polyester is less soluble in EG.

[0098] In addition, when the process of the present invention is carried out for multiple cycles or multiple times, o-BHET produced or obtained in the second depolymerization step in the previous cycle or previous time (including but not limited to the previous cycle or previous time, for example, the previous cycle or previous time, the previous cycle or previous time, or multiple previous cycles or previous times) can be utilized in the first depolymerization step of the subsequent process (including but not limited to the next cycle or next time, for example, the next cycle or next time, a later cycle or later time, or multiple later cycles or later times). In this way, the overall recycling efficiency and / or recycling rate of polyester can be increased, which in turn can reduce the overall recycling cost.

[0099] It will be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the scope or spirit of the present invention. In view of the foregoing, it is intended that the present invention cover modifications and variations provided they come within the scope of the appended claims and their equivalents. [Industrial Applicability]

[0100] By using the process of the present invention, the polyester in the recycled material (e.g., recycled fabric) can be recycled. Furthermore, the recycled polyester can be reused, including, but not limited to, the production of fabrics, containers, sheets, packaging materials, films, and other polyester-containing products. [Explanation of symbols]

[0101] S11, S12, S20, S30, S40, S51, S52: Step

Claims

1. Providing a recycled material containing polyester; carrying out a first depolymerization step, which includes mixing the recycled material with oligo-bis(2-hydroxyethyl)terephthalate (o-BHET) to react and extrusion depolymerize to obtain or produce at least poly-bis(2-hydroxyethyl)terephthalate (p-BHET); carrying out a second depolymerization step, which includes mixing the p-BHET with a depolymerization solution to carry out chemical depolymerization to obtain or produce at least monomer-bis(2-hydroxyethyl)terephthalate (m-BHET); A method for processing recyclates, comprising:

2. 2. The method for treating recycle material according to claim 1, wherein the weight ratio of the o-BHET to the total weight of the mixture in the first depolymerization step is 5% by weight to 20% by weight.

3. 2. The method for treating recycle materials according to claim 1, wherein the first depolymerization step further comprises mixing the recycle material, the o-BHET, and a catalyst.

4. 4. The method for treating recycles according to claim 3, wherein the weight ratio of the catalyst to the total weight of the mixture in the first depolymerization step is 0.2% by weight to 8% by weight.

5. 2. The method for treating recycle material according to claim 1, wherein the first depolymerization step further comprises heating to 200°C to 280°C.

6. 2. The method for treating recycle as claimed in claim 1, wherein the first depolymerization step is carried out for 1 to 10 minutes.

7. 2. The method for treating recycles according to claim 1, wherein the depolymerization solution contains ethylene glycol, and the weight ratio of the ethylene glycol to the total weight of the mixture in the second depolymerization step is 30% by weight to 80% by weight.

8. 2. The method for treating recycle material according to claim 1, wherein the second depolymerization step further comprises heating to 190°C to 240°C.

9. 2. The method for treating recycle material according to claim 1, wherein the second depolymerization step is carried out for 0.5 to 5 hours.

10. The first depolymerization step is performed at least M times or M cycles, and the second depolymerization step is performed at least N times or N cycles, where M and N are both natural numbers, and M is greater than N; The method for treating recycle rate according to claim 1, wherein the o-BHET used for mixing in the Mth or Mth cycle of the first depolymerization step includes the o-BHET obtained or produced in the Nth or Nth cycle of the second depolymerization step.

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