Efficient chemical recovery method of waste polyester fabric

Abstract

The invention provides a chemical recovery method of a polyester fabric. The polyester fabric is extracted by using a composite solvent, and is filtered to obtain a decolorized polyester fabric, the composite solvent contains alcohol ether and phenyl ether, and the decolorized polyester fabric contains the composite solvent. Afterwards, ethylene glycol is added into the decolored polyester fabric to be depolymerized into the ethylene glycol terephthalate monomer.

Description

Technical Field

[0001] The invention relates to a high-efficiency chemical recycling method for fabrics and to a high-efficiency chemical recycling method for waste polyester fabrics. Background Art

[0002] In conventional polyester fabric recycling methods, the pre-treatment process usually first decolorizes the waste PET fabric to achieve the decolorization effect, including using a solvent to extract the dye, and then drying the decolorized PET fabric to remove the solvent, and then chemically recovering the dried PET fabric. In the pre-treatment process, the fabric drying process requires heating to evaporate the solvent, and the evaporated solvent is then condensed and recovered. This process has disadvantages, including (1) the residual solvent in the fabric must be less than 1.0% to avoid affecting the depolymerization of PET, (2) drying requires equipment and energy consumption, and (3) there will be solvent leakage in the solvent recovery process.

[0003] After the bleached PET fabric, EG (ethylene glycol) is used to depolymerize PET to obtain BHET monomer (Bis (2-Hydroxy Ethyl) Terephthalate) product, which is then purified to obtain clean BHET monomer, which is generally referred to as "BHET monomer chemical recovery process". In the conventional BHET monomer chemical recovery process, the depolymerization reaction is carried out at 190°C to 240°C. The disadvantages of this process include (1) high temperature, (2) long depolymerization time, (3) low selectivity, and (4) yellowish hue of BHET.

[0004] Based on the above, the conventional pre-treatment process and BHET monomer chemical recovery process have the problems of high cost and poor quality. Therefore, developing an efficient chemical recovery method for waste polyester fabrics can solve the problems of high cost and poor quality in the conventional technology, which is an important research topic currently required. Summary of the invention

[0005] The invention provides a chemical recycling method for polyester fabrics, which can effectively solve the problems of high cost and poor quality in the prior art.

[0006] The chemical recycling method of polyester fabric of the present invention comprises the following steps: extracting polyester fabric with a composite solvent, filtering to obtain decolorized polyester fabric, wherein the composite solvent contains alcohol ether and phenyl ether, and the decolorized polyester fabric contains the composite solvent; then, adding ethylene glycol to the decolorized polyester fabric to depolymerize it into ethylene terephthalate monomer.

[0007] In one embodiment of the present invention, the alcohol ether includes ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol phenyl ether or a combination thereof, and the phenyl ether includes anisole, phenylethyl ether, phenylpropyl ether, phenylbutyl ether, methyl anisole, methyl phenylethyl ether, methyl phenylpropyl ether, methyl phenylbutyl ether or a combination thereof.

[0008] In one embodiment of the present invention, the weight ratio of the composite solvent to the polyester fabric is 3:10 to 10:10.

[0009] In one embodiment of the present invention, the extraction temperature is 110°C to 150°C.

[0010] In one embodiment of the present invention, the extraction time is 10 minutes to 60 minutes.

[0011] In one embodiment of the present invention, the extraction is performed 2 to 6 times.

[0012] In one embodiment of the present invention, in the composite solvent, the weight ratio of the alcohol ether to the phenyl ether is 1:9 to 9:1.

[0013] In one embodiment of the present invention, the weight ratio of ethylene glycol to the bleached polyester fabric is 2:1 to 6:1.

[0014] In one embodiment of the present invention, the depolymerization catalyst includes an organic metal and an ionic liquid, and the organic metal includes zinc acetate, organic titanium, organic antimony or organic aluminum.

[0015] In one embodiment of the present invention, the weight ratio of the depolymerization catalyst to the decolorized polyester fabric is 0.5:100 to 10:100.

[0016] In one embodiment of the present invention, the depolymerization temperature is 140°C to 190°C.

[0017] In one embodiment of the present invention, the depolymerization time is 1.5 hours to 5 hours.

[0018] In one embodiment of the present invention, the ionic liquid includes 1-butyl-3-methylimidazolium hexa-fluoro-phosphate (BMI-PF6) and 1-butyl-3-methylimidazolium tetra-fluoro-borate (BMI-BF4).

[0019] Based on the above, the present invention provides a chemical recycling method for polyester fabrics, using a composite solvent (alcohol ether + phenyl ether) as a solvent for pre-treatment of waste PET fabrics, and using the composite solvent as a co-solvent (or auxiliary solvent) for depolymerization of BHET monomers in a chemical recycling process. The composite solvent has both the functions of a pre-treatment extraction solvent and a co-solvent for depolymerization, and therefore can effectively solve the problems of high cost and poor quality in the conventional technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] none DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described in detail. However, these embodiments are illustrative only, and the present invention is not limited thereto.

[0022] In this article, the range expressed by "a value to another value" is a summary expression method to avoid listing all the values ​​in the range one by one in the specification. Therefore, the description of a specific numerical range covers any value in the numerical range and a smaller numerical range defined by any value in the numerical range, just as the arbitrary value and the smaller numerical range are written in the description text of the specification.

[0023] The invention provides a chemical recycling method for polyester fabrics, comprising the following steps: extracting the polyester fabrics with a composite solvent, filtering to obtain decolorized polyester fabrics, wherein the composite solvent contains alcohol ether and phenyl ether, and the decolorized polyester fabrics contain the composite solvent; then, adding ethylene glycol to the decolorized polyester fabrics to depolymerize them into ethylene terephthalate monomers.

[0024] In the present embodiment, a composite solvent is used to extract polyester fabric. Polyester fabric is, for example, waste polyester fabric, and may include scraps or defective products from waste clothing, textile factories, etc. The PET content of the waste polyester fabric is, for example, more than 90wt%, and impurities such as dyes and glue are less than 10wt%. The composite solvent contains alcohol ether and phenyl ether, and the alcohol ether may include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol phenyl ether or a combination thereof, and phenyl ether may include anisole, phenylethyl ether, phenylpropyl ether, phenylbutyl ether, methyl anisole, methyl phenylethyl ether, methyl phenylpropyl ether, methyl phenylbutyl ether or a combination thereof, but the present invention is not limited thereto. More specifically, the weight ratio of alcohol ether to phenyl ether is, for example, 1:9 to 9:1, preferably, 2:8 to 8:2; the weight ratio of the composite solvent to the polyester fabric is, for example, 3:10 to 10:10, preferably, 4:10 to 9:10. In terms of the operating conditions of the extraction, the temperature for the extraction is, for example, 110°C to 150°C, preferably, 120°C to 140°C; the time for the extraction is, for example, 10 minutes to 60 minutes, preferably, 20 minutes to 40 minutes; the number of extractions is, for example, 2 to 6 times, preferably, 3 to 5 times.

[0025] In this embodiment, a composite solvent is used to extract the polyester fabric, and the decolorized polyester fabric is obtained by filtering. The decolorized polyester fabric contains the composite solvent. The decolorized fabric does not need to be dried, and is further depolymerized with ethylene glycol to obtain a crude product of ethylene terephthalate monomer. In more detail, the weight ratio of ethylene glycol to the decolorized polyester fabric is, for example, 2:1 to 6:1, and preferably, 3:1 to 4:1. The depolymerization catalyst may include an organic metal and an ionic liquid. The organic metal may include zinc acetate, organic titanium, organic antimony or organic aluminum. The ionic liquid may include 1-butyl-3-methylimidazoliumhexa-fluoro-phosphate (BMI-PF6) and 1-butyl-3-methylimidazoliumtetrafluoroborate (BMI-BF4). In terms of the operating conditions for depolymerization, the weight ratio of the depolymerization catalyst to the bleached polyester fabric is, for example, 0.5:100 to 10:100, preferably, 1:100 to 5:100; the depolymerization temperature is, for example, 140°C to 190°C, preferably, 150°C to 180°C; the depolymerization time is, for example, 1.5 hours to 5 hours, preferably, 2 hours to 4 hours.

[0026] In this embodiment, the selectivity of ethylene terephthalate monomer is, for example, above 90%. The crude ethylene terephthalate monomer is purified by activated carbon adsorption of impurities, crystallization, filtration and drying to obtain purified ethylene terephthalate monomer, which is then polymerized into r-PET. The quality of r-PET is L>62%, a±1.0, b±2.0.

[0027] The chemical recycling method of polyester fabric proposed by the present invention is described in detail below by means of experimental examples. However, the following experimental examples are not intended to limit the present invention.

[0028] Experimental example

[0029] In order to prove that the chemical recycling method of polyester fabric proposed by the present invention has both separation and decolorization procedures and can effectively solve the problems of high cost and poor quality in the conventional technology, the following experimental example is specifically made.

[0030] Example 1

[0031] Take 103g of waste PET fabric (L=22.5%, a=4.4, b=5.6), of which impurities such as dyes account for 3g and PET material accounts for 100g.

[0032] (1) Pre-treatment process:

[0033] The waste PET fabric was placed in a 1L three-necked glass flask, and 600g of composite solvent A (ethylene glycol ethyl ether / ethylene glycol butyl ether / propylene glycol methyl ether / anisole / methyl phenyl butyl ether = 2 / 1 / 3 / 2 / 2, weight ratio) was poured in, and then heated to 128°C and kept at this temperature for 0.5hr, and then filtered with a vacuum bottle to separate the fabric from the composite solvent A, which is the first extraction procedure. The wet-based fabric (175g) after filtration contained 101g of fabric (including dyes, etc.) and 74g of the composite solvent.

[0034] Then, the wet-based fabric is put back into the three-necked glass flask, and 526g of the composite solvent is added, and the fabric is also heated to 128°C and kept at this temperature for 0.5 hours, and then filtered to separate the fabric from the composite solvent, which is the second extraction procedure. The third extraction procedure is the same as the second extraction procedure. After the three extractions, the waste PET fabric has L=85.4%, a=1.7, and =2.3. The wet-based decolorized fabric (174g, composite solvent / fabric=74 / 100) enters the PET depolymerization process without drying because the composite solvent A (alcohol ether + phenyl ether) is the PET depolymerization co-solvent of the BHET monomer chemical recovery process.

[0035] (2) BHET monomer chemical recovery process:

[0036] The wet-based fabric was then placed in a three-necked glass flask, and 26 g of a composite solvent, 300 g of ethylene glycol (EG), and 1 g of zinc acetate were added as a catalyst. After heating to 150° C. and maintaining for 2.5 hours, PET was depolymerized into a crude BHET product, wherein the conversion rate of PET was 100%, the selectivity of BHET monomer (m-BHET) was 90.4%, and the selectivity of by-products such as BHET oligomers (dimers or trimers or above, o-BHET) was 10.6%.

[0037] The temperature of the crude product is cooled from 150°C to 18°C ​​for BHET monomer crystallization, and then filtered with a 5μm filter to obtain a wet-based BHET monomer filter cake. The wet-based BHET filter cake is then placed in a 1L three-necked glass flask, 518g of pure water is added, stirred and heated to 90°C for 0.5hr, and then filtered with a 1μm filter to filter out BHET oligomers. 1g of powdered activated carbon is added to the filtrate at 90°C to adsorb impurities and the activated carbon is filtered out with a 0.5μm filter. The filtrate is cooled from 90°C to 5°C for BHET monomer crystallization, and then filtered with a 1μm filter to obtain BHET monomer crystals, which are then dried with hot air at 70°C. The BHET moisture content is less than 1% to facilitate repolymerization.

[0038] (3) Repolymerization process:

[0039] BHET monomer was polycondensed to obtain r-PET, with hue quality L=66.4%, =1.1, b=1.7.

[0040] By using a composite solvent as the extraction solvent for pre-treatment and the co-solvent for depolymerization, the fabric pre-treatment process does not require drying, and the production line does not need to invest in drying equipment, saving energy consumption of 30 to 150 cal / g fabric; in the depolymerization unit, the depolymerization temperature can be reduced and the selectivity is high, and the production line has the advantages of low energy consumption and high production capacity; in terms of quality, the recycled r-PET has the advantages of high selectivity and low hue quality.

[0041] Example 2 to Example 6

[0042] The composite solvent formula, dosage, type and amount of depolymerization catalyst, amount of EG added for depolymerization and other depolymerization temperatures after pretreatment of PET fabric were changed respectively (please refer to Table 1), and the rest were the same as Example 1. The yield and color quality of r-PET are shown in Table 1.

[0043] The compound solvent formula is as follows:

[0044] Example 2 uses composite solvent B: (ethylene glycol ethyl ether / ethylene glycol phenyl ether / propylene glycol methyl ether / phenyl ether / methyl phenyl ether=1 / 2 / 3 / 2 / 2, weight ratio).

[0045] Example 3 uses composite solvent C: (ethylene glycol butyl ether / propylene glycol methyl ether / propylene glycol phenyl ether / phenyl ethyl ether / methyl anisole = 3 / 2 / 1 / 2 / 2, weight ratio).

[0046] Example 4 uses composite solvent D: (ethylene glycol ethyl ether / propylene glycol ethyl ether / phenethyl ether / methyl phenbutyl ether=3 / 3 / 2 / 2, weight ratio).

[0047] Example 5 uses composite solvent E: (ethylene glycol ethyl ether / ethylene glycol propyl ether / propylene glycol propyl ether / phenylbutyl ether / methylphenylpropyl ether=2 / 1 / 3 / 2 / 2, weight ratio).

[0048] Example 6 Using composite solvent F: (ethylene glycol methyl ether / ethylene glycol ethyl ether / propylene glycol butyl ether / phenylpropyl ether / methyl phenylbutyl ether=2 / 1 / 3 / 2 / 2, weight ratio)

[0049] As shown in Table 1, Examples 1 to 6 of the chemical recycling method for polyester fabrics of the present invention have a high selectivity of BHET monomer (above 90.0%), and the L / a / b of the recycled r-PET is above 62.% / ±1.0 / ±2.0, which has the advantage of good hue. In addition, the fabric pre-treatment process does not require drying, the production line does not need to invest in drying equipment, and does not generate drying energy consumption, which has the advantages of energy saving and cost reduction.

[0050] Table 1

[0051]

[0052]

[0053] Comparative Example 1

[0054] Take 103g of waste PET fabric (L=22.5%, a=4.4, b=5.6), of which impurities such as dyes account for 3g and PET material accounts for 100g.

[0055] (1) Pre-treatment process:

[0056] The waste PET fabric was placed in a 1L three-necked glass flask, and 600g of o-xylene was poured into it. The flask was heated to 128°C and kept at this temperature for 0.5hr. The fabric was then filtered with a vacuum bottle to separate the o-xylene from the fabric. This was the first extraction procedure. The wet-based fabric (164g) after filtration contained 101g of fabric (including dyes, etc.) and 63g of o-xylene.

[0057] Then put the wet-based fabric back into the three-necked glass flask, add 537g of o-xylene, heat to 128°C and keep the temperature for 0.5hr, and then filter to separate the fabric from o-xylene, which is the second extraction procedure. The third extraction procedure is the same as the second. After three extractions, the waste PET fabric has L=86.1%, a=1.9, =2.1, wet-based decolorized fabric (169g, xylene / fabric=69 / 100), and is dried in a dryer to reduce the o-xylene residue in the fabric to 0.5g / 100g fabric, which is beneficial to the subsequent BHET monomer chemical recovery process. In the drying process, the wet-based decolorized fabric is heated at 125°C, and the o-xylene is vaporized by heat and separated from the fabric. The vaporized o-xylene is then condensed to recover 58.1g of o-xylene, and the o-xylene leakage rate is 10.9g / 100g fabric.

[0058] (2) BHET monomer chemical recovery process:

[0059] The dried fabric was placed in a three-necked glass flask, 400 g of ethylene glycol (EG) and 1 g of zinc acetate were added as a catalyst, and the PET was depolymerized into a crude BHET product after being heated to 195° C. and maintained for 4 hours, wherein the conversion rate of PET was 100%, the selectivity of BHET monomer (m-BHET) was 79.2%, and the selectivity of by-products such as BHET oligomers (dimers or trimers or above, o-BHET) was 20.8%.

[0060] The temperature of the crude product is cooled from 195 to 18°C ​​for BHET monomer crystallization, and then filtered with a 5μm filter to obtain a wet-based BHET monomer filter cake. The wet-based BHET filter cake is then placed in a 1L three-necked glass flask, 518g of pure water is added, stirred and heated to 90°C for 0.5hr, and then filtered with a 1μm filter to filter out BHET oligomers. 1g of powdered activated carbon is added to the filtrate at 90°C to adsorb impurities and the activated carbon is filtered out with a 0.5μm filter. The filtrate is cooled from 90°C to 5°C for BHET monomer crystallization, and then filtered with a 1μm filter to obtain BHET monomer crystals, which are then dried with hot air at 70°C. The BHET moisture content is less than 1% to facilitate repolymerization.

[0061] (3) Repolymerization process:

[0062] BHET monomer was polycondensed to obtain r-PET, with hue quality L=60.4%, =1.9, b=3.7.

[0063] Using xylene as the extraction solvent for pretreatment and no co-solvent during depolymerization, the test results are shown in Table 2. The selectivity of BHET monomer is low (79.2%), and the L / a / b of the recovered r-PET is 60.4% / 1.9 / 3.7, which has disadvantages such as hue difference. In addition, the fabric pretreatment process requires drying, and the production line needs to invest in drying equipment and use energy consumption of 55cal / g fabric, and the leakage rate of recovered o-xylene is 0.019g / g fabric;.

[0064] The yield and color quality of r-PET of Comparative Examples 2 to 6 are shown in Table 2. The descriptions of Comparative Examples 2 to 6 are as follows.

[0065] Comparative Example 2

[0066] The fabric was not dried during the pre-treatment process, and the rest was the same as in Comparative Example 1. The selectivity of BHET monomer was low (76.4%); the L / a / b of the recycled r-PET was 61.4% / 2.4 / 4.2, and it had disadvantages such as hue difference.

[0067] Comparative Example 3

[0068] The depolymerization temperature of the BHET monomer chemical recovery process was changed to 150°C, and the rest was the same as Comparative Example 1. The BHET monomer had low selectivity (45.8%), and the L / a / b of the recovered r-PET was 60.8% / 1.5 / 3.4, which had disadvantages such as hue difference. In addition, the fabric pre-treatment process required drying, and the production line needed to invest in drying equipment and use energy consumption of 55 cal / g fabric, and the leakage rate of recovered o-xylene was 0.019 g / g fabric.

[0069] Comparative Example 4

[0070] The EG in the BHET monomer chemical recovery process was reduced from 400g to 300g, and 100g of anisole was added for depolymerization, and the rest was the same as in Comparative Example 3. Although the selectivity of BHET monomer was high (90.3%), the L / a / b of the recovered r-PET was 64.1% / 1.0 / 1.7, and the hue was good. However, the fabric pretreatment process required drying, and the production line needed to invest in drying equipment and use energy consumption of 55cal / g fabric, and the leakage rate of recovered xylene was 0.019g / g fabric.

[0071] Comparative Example 5

[0072] Extraction solvent / fabric 1,000 / 103g, extraction temperature 140°C, extraction time 60 minutes, extraction times 6 times, catalyst 2g, depolymerization temperature 150°C, and the rest are the same as Comparative Example 3. BHET monomer low selectivity (86.7%), L / a / b of the recovered r-PET = 63.7% / 1.1 / 1.5, good hue.

[0073] Comparative Example 6

[0074] Ethylene glycol was used instead of o-xylene as the extraction solvent for pretreatment, and 100 g of anisole was added during depolymerization, and the rest was the same as in Comparative Example 2. The selectivity of BHET monomer was high (91.4%); but the L / a / b of the recovered r-PET was 55.4% / 2.5 / 6.1, which had a disadvantage of poor hue.

[0075] Table 2

[0076]

[0077]

[0078] The chemical recycling method of polyester fabric of the present invention mainly uses a composite solvent to extract dye from waste PET fabric to achieve fabric decolorization, and the decolorized PET fabric contains the composite solvent. The decolorized PET fabric containing the composite solvent is directly added with ethylene glycol to depolymerize into ethylene terephthalate monomer. In the whole process, the PET fabric does not need to be dried, and the depolymerization has the characteristics of low temperature and high BHET selectivity, which has a low-cost benefit for the process.

[0079] The composite solvent (alcohol ether+phenyl ether) of the invention can simultaneously effectively decolorize waste PET fabrics and accelerate the depolymerization of PET into BHET. The principle is that ethers have affinity with the PET structure, and alcohol ether is more affinity with the EG segment monomer in the PET structure, while phenyl ether is more affinity with the PTA segment monomer in the PET structure, and has more excellent decolorization and depolymerization functions.

[0080] Waste PET fabrics contain impurities such as dyes and surface treatment agents. In the present invention, a composite solvent (alcohol ether + phenyl ether) is used to extract impurities such as dyes to achieve purification effects such as decolorization. The decolorized PET fabric does not need to be dried, and then depolymerized with EG to form BHET monomers. Because the composite solvent has the role of both an extraction solvent and a co-solvent for depolymerization, compared with the prior art, the PET fabric does not need to be dried, and has high depolymerization efficiency, high BHET selectivity, and low hue and other high quality. The composite solvent is a solvent for decolorization and depolymerization at the same time. The decolorized PET fabric containing the composite solvent is depolymerized into BHET monomers in the presence of EG and a catalyst to reduce costs and improve quality. In addition, the composite solvent used in the present invention also has advantages in being environmentally friendly.

[0081] In summary, the present invention provides a chemical recovery method for polyester fabrics, using a composite solvent (alcohol ether + phenyl ether) as a solvent for pre-treatment of waste PET fabrics, and using the composite solvent as a co-solvent (or co-solvent) for depolymerization of BHET monomers in a chemical recovery process, wherein the composite solvent has both the function of a solvent for pre-treatment extraction and a co-solvent for depolymerization. In this way, after decolorizing the waste PET fabric using the composite solvent, the depolymerization process can be directly entered without drying to reduce costs. The composite solvent remaining in the PET fabric is also a co-solvent for depolymerization. In the presence of the co-solvent, PET depolymerization has the advantages of low-temperature depolymerization, high BHET selectivity, and good hue, and therefore, the quality can be improved.

Claims

1. A chemical recycling method for polyester fabrics, characterized in that: include: Extracting the polyester fabric with a composite solvent, filtering to obtain the decolorized polyester fabric, wherein the composite solvent contains alcohol ether and phenyl ether, and the decolorized polyester fabric contains the composite solvent; and Ethylene glycol is added to the discolored polyester fabric to depolymerize into ethylene terephthalate monomers.

2. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The alcohol ethers include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol phenyl ether or a combination thereof; the phenyl ethers include anisole, phenylethyl ether, phenylpropyl ether, phenylbutyl ether, methyl anisole, methyl phenylethyl ether, methyl phenylpropyl ether, methyl phenylbutyl ether or a combination thereof.

3. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The weight ratio of the composite solvent to the polyester fabric is 3:10 to 10:

10.

4. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The extraction is carried out at a temperature of 110°C to 150°C.

5. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The extraction is carried out for a period of time ranging from 10 minutes to 60 minutes.

6. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The number of extractions performed ranges from 2 to 6 times.

7. The chemical recycling method of polyester fabric according to claim 1, characterized in that: In the composite solvent, the weight ratio of alcohol ether to phenyl ether is 1:9 to 9:

1.

8. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The weight ratio of ethylene glycol to the decolorized polyester fabric is 2:1 to 6:

1.

9. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The depolymerization catalyst includes organic metal and ionic liquid, and the organic metal includes zinc acetate, organic titanium, organic antimony or organic aluminum.

10. The chemical recycling method of polyester fabric according to claim 9, characterized in that: The weight ratio of the depolymerized catalyst to the decolorized polyester fabric is 0.5:100 to 10:

100.

11. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The temperature of the depolymerization is 140°C to 190°C.

12. The chemical recycling method of polyester fabric according to claim 1, characterized in that: The depolymerization time is 1.5 hours to 5 hours.

13. The chemical recycling method of polyester fabric according to claim 9, characterized in that: The ionic liquid includes 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium tetrafluoroborate.

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