Regenerated polyester fiber and preparation method thereof

Abstract

The invention discloses a preparation method of regenerated polyester fibers, which comprises the following steps: firstly, preparing regenerated polyester, recycling polyester waste by utilizing the recycling performance of the regenerated polyester, and adopting a combined degradable additive in a form of combining two components, so that an optimal combination is used on the premise of meeting excellent degradability; the inorganic powder filler has the advantages of good wear resistance and high strength, and elements for enhancing the compatibility of the components are used; the isocyanate-based silane coupling agent and the lithium silicate in the mixed coupling agent have a synergistic enhancement effect, and are greatly beneficial to the mechanical properties of the regenerated fibers. The regenerated polyester fiber prepared by the method disclosed by the invention has environmental protection property and economical efficiency under the condition of keeping the use performance of the fiber, can be recycled for multiple times, and has important significance in the field of textile fiber recycling.

Description

Technical Field

[0001] The present invention relates to the technical field of regenerated fiber preparation, and in particular to a regenerated polyester fiber and a preparation method thereof. Background Art

[0002] Polyester fiber, due to its excellent physical properties and chemical stability, is widely used in textiles, clothing, household goods, and other fields. However, the production of traditional polyester fiber relies on petrochemical raw materials, which not only consumes a large amount of non-renewable resources but also pollutes the environment. With the increasing awareness of environmental protection, the research and development of recycled polyester fiber has become an industry hotspot.

[0003] Recycled polyester fiber is made from recycled polyester bottle flakes, spinning waste, pulp, and other raw materials through a series of spinning processes. It is a renewable resource and is widely used in bedding, clothing, furniture, and toys, as fillings. In recent years, with the growing conflict between resource shortages and environmental degradation, crude oil resources have fundamentally influenced the price of polyester raw materials. Therefore, using recycled polyester fiber to replace traditional polyester and reduce oil consumption has a significant and positive impact on promoting the development of a circular economy.

[0004] Currently, the main methods for producing regenerated polyester fibers include physical and chemical recycling. Physical recycling, through melt regeneration, is simple but yields poor fiber performance. Chemical recycling, through depolymerization and repolymerization, can produce fibers with higher performance, but the process is complex and costly. Furthermore, the recycling of polyester waste cannot be the ultimate solution to its environmental pollution. First, the amount of polyester waste that can be recycled is limited. Products containing large amounts of additives or other difficult-to-remove impurities, as well as products that have been recycled multiple times, present significant challenges. Second, a large number of polyester products that are difficult to collect, such as agricultural film and garbage bags, are also unsuitable for recycling. Finally, products that are prohibitively expensive or have no recycling value are not worth recycling. Therefore, it is necessary to modify the polyester produced from these products to make them environmentally degradable, so that the waste can naturally decompose into small molecular products within a certain period of time in nature, ultimately returning them to the natural material cycle. Therefore, developing a regenerated polyester fiber and its preparation method that maintains fiber performance while being both environmentally friendly and economical is of great significance.

[0005] To this end, we disclose a regenerated polyester fiber and a preparation method thereof. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a regenerated polyester fiber and a preparation method thereof.

[0007] To achieve the above objectives, the present invention proposes the following technical solutions:

[0008] A regenerated polyester fiber is obtained by extrusion spinning a regenerated melt, which is obtained by melting a regenerated mixed material. The regenerated mixed material comprises the following raw material components in parts by weight:

[0009]

[0010] Furthermore, the recycled polyester comprises the following processing steps:

[0011] A1. Collect waste plastics, remove large debris, and sort them by type and color. The sorted waste plastics are crushed into 3-5 cm particles. The crushed waste plastic particles are sent to a cleaning tank, where cleaning water is added to clean the waste plastic particles. After cleaning, the waste plastic particles are removed and drained to obtain polyester waste.

[0012] A2, the polyester waste, the catalyst zinc acetate and the alcoholysis agent ethylene glycol are mixed and stirred uniformly to obtain a mixed solution, the mixed solution is heated under nitrogen protection to perform a depolymerization reaction to obtain an alcoholysis solution, and the mixture is kept warm for standby use;

[0013] A3, filtering the alcoholysis solution twice, discarding the filter residue, and then adding methanol, a decolorizing agent, and antimony trioxide to the filtered liquid for polycondensation to obtain regenerated polyester;

[0014] Among them, the decolorizing agent is one of Dove decolorizing agent, Cetaphil decolorizing agent, and Yashuang decolorizing agent.

[0015] Furthermore, in step A2, the temperature of the heated mixed solution is 190-200° C., and the heating time of the reaction solution is 3-5 hours; in step A3, the polycondensation reaction temperature is 220-240° C., and the reaction time is 2-3 hours.

[0016] Furthermore, in step A3, the secondary filtration includes primary filtration and secondary filtration:

[0017] The first stage filtration adopts a mesh filter, the first stage filtration pressure is 0.1-0.4MPa, the first stage filtration precision is 10-500mm, the second stage filtration pressure is 0.1-0.4MPa, the second stage filtration precision is 10-100mm;

[0018] The secondary filtration uses a plate and frame filter. The first stage filtration pressure is 0.2-0.4MPa, the first stage filtration accuracy is 0.1-5mm, the second stage filtration pressure is 0.2-0.4MPa, and the second stage filtration accuracy is 10-100mm.

[0019] Furthermore, the combined degradable additive includes modified regenerated silk fibroin and cellulose carbamate, and the mass ratio of the modified regenerated silk fibroin to the cellulose carbamate is (7.8-9.2):(0.2-0.8).

[0020] Furthermore, the swelling agent is dimethyl sulfoxide; and the inorganic powder filler is modified boron nitride.

[0021] Furthermore, the mixed coupling agent is a mixture of an isocyanate silane coupling agent and lithium silicate, and the mass ratio of the two is (7.8-9.2): (0.2-0.8).

[0022] Furthermore, the preparation method of the regenerated polyester fiber comprises the following steps:

[0023] S1. Evenly mixing recycled polyester, polyester waste, a combined degradable additive, an inorganic powder filler, a swelling agent, and a mixed coupling agent according to a proportion to obtain a mixture, and heating the mixture until it is melted to obtain a recycled melt;

[0024] S2. The regenerated melt is transported to a spinning device for extrusion spinning to obtain regenerated polyester staple fibers.

[0025] Furthermore, in step S2, the melt extrusion temperature is 220-230°C, the spinning speed is 1000-1500 m / min, and the fineness of the regenerated polyester fiber filament is 100-120 dtex.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] The present invention discloses a method for preparing regenerated polyester fiber. First, the regenerated polyester prepared utilizes the recyclability of the regenerated polyester to recycle and reuse polyester waste. The combined degradable additive uses a two-component combination, using an optimized combination while ensuring excellent degradability. The inorganic powder filler has the advantages of good wear resistance and high strength, and an element that enhances component compatibility is used. The isocyanate silane coupling agent and lithium silicate in the mixed coupling agent have a synergistic reinforcement effect, which greatly improves the mechanical properties of the regenerated fiber. The regenerated polyester fiber prepared by the present invention is environmentally friendly and economical while maintaining the fiber's usability. It can also be recycled and reused multiple times, and is of great significance in the field of textile fiber recycling.

[0028] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the present subject matter disclosure.

[0029] The foregoing and other aspects, embodiments and features of the present invention will be more fully understood from the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or will be learned from the practice of the specific embodiments according to the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples, but this should not be construed as limiting this patent.

[0031] Unless otherwise specified, the experimental methods or test methods described in the following examples / comparative examples are conventional methods; the reagents and materials described are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0032] In the present invention, the preparation process of modified regenerated silk fibroin includes MXene colloid preparation, regenerated silk fibroin solution preparation, and curing modification. The specific preparation process is as follows:

[0033] 1) Preparation of MXene colloids

[0034] A certain mass of lithium fluoride is added to a volume (V) of hydrochloric acid at a concentration of 8-10 mol / L. Stir and heat at 40-60°C for 10-30 minutes, then add an equal mass of Ti3AlC2 to the lithium fluoride. Stir at 40-60°C for 18-30 hours. After the reaction is complete, the mixture is washed several times with deionized water by centrifugation until the pH is ≥ 6. After adding 2-3 volumes (V) of deionized water, ultrasonicate in an ice-water bath under inert gas protection for 10-50 minutes. After centrifugation, the supernatant is collected to obtain a monolayer MXene colloid, which is then vacuum-dried to obtain the MXene colloid used in the present invention.

[0035] 2) Preparation of regenerated silk fibroin solution

[0036] Silk is placed in a 0.05-0.55wt% sodium carbonate solution and boiled at 90-100°C for 30-45 minutes. The silk is then rinsed with 60°C deionized water. This process is repeated at least three times to remove sericin from the silk surface. The silk is then dried in a 60°C oven for 10-15 hours to produce degummed silk. The degummed silk is then added to an 8.3-10.3 mol / L lithium bromide solution and heated and stirred at 60°C for 5-7 hours. Once completely dissolved, the silk is centrifuged at 9,000-10,000 rpm for 20-30 minutes. This process is repeated three times to remove insoluble impurities. The centrifuged silk fibroin solution is then dialyzed with ultrapure water for 3-5 days. The molecular weight cutoff of the dialysis bag is 8000-1000, and the water is changed every 4-12 hours. After the dialysis is completed, centrifugation is performed at 9000-10000 rpm for 20-30 minutes at room temperature, and repeated 3 times to completely remove impurities. The silk fibroin concentration after dialysis is approximately 60-80 mg / mL.

[0037] 3) Curing modification

[0038] Take the above-mentioned dialyzed silk fibroin solution, then add MXene colloid with a relative silk fibroin mass of 1.5-4.5wt%, then add 8-10 times the volume of ultrapure water of the silk fibroin solution and stir, then add CaCl2 to make the calcium ion concentration 4.5-5.5mg / mL, and finally add 45-55wt% tannic acid aqueous solution with the same volume as the silk fibroin solution, stir until viscose substance appears, and wash with ultrapure water several times to obtain composite silk fibroin, that is, modified regenerated silk fibroin.

[0039] Furthermore, cellulose carbamate is treated with urea and cellulose and synthesized by a solid-liquid phase method. Specifically, lignocellulose and urea are mixed in a molar ratio of 1: (0.9-1.8), and then stirred with N, N-dimethylacetamide. The amount of N, N-dimethylacetamide used is based on the amount of solid matter. The evenly stirred mixture is placed in a reactor. The mixture must not exceed two-thirds of the volume of the reactor. The reactor is heated and kept warm for 4-6 hours, and the stirring rate is controlled at 150-200 rpm. After the stirring is completed, the reactor is cooled to room temperature, and then filtered through a filter to obtain the product, and then washed with distilled water to remove residual N, N-dimethylacetamide and urea. Finally, the sample is placed at 60°C and dried to obtain the cellulose carbamate of the present invention.

[0040] Among them, N,N-dimethylacetamide acts as a reaction medium and does not participate in the reaction. It uses its strong polarity to destroy the abundant hydrogen bonds in cellulose, thereby allowing cellulose to fully react with the isocyanate after the decomposition of urea. This can also reduce the production of by-products. The by-products are soluble in water and are not easy to pollute the environment.

[0041] Furthermore, the inorganic powder filler is modified boron nitride, and the modified boron nitride is prepared as follows: graphite oxide prepared by a modified Hummers method is ultrasonically exfoliated to obtain graphene oxide, which is then thermally reduced to obtain graphene. A certain mass of graphene is dispersed in a mixed dispersion, and then vacuum filtered, solids collected, washed multiple times, and dispersed with an acetic acid solution. Boron nitride equal to half the mass of the graphene is added, and the mixture is condensed and refluxed at 75-80°C for 6-10 hours. After completion of the reaction, the mixture is filtered sequentially through anhydrous ethanol and deionized water, and then washed multiple times with deionized water. The solids are collected and dried at 60°C to obtain the modified boron nitride.

[0042] The mixed dispersion is prepared by mixing N,N-dimethylacetamide and an isocyanate silane coupling agent in a mass ratio of 1:1. The components in the mixed dispersion not only facilitate the preparation of modified boron nitride, but are also identical to those in the preparation of cellulose carbamate, thereby enhancing the compatibility between the materials. Furthermore, the combination of the coupling agent and graphene facilitates interfacial compatibility of the filler in the polyester matrix. Furthermore, boron nitride has excellent structural stability and wear resistance, and can prevent the development of microcracks when subjected to mechanical impact, thereby enhancing the mechanical properties of the material.

[0043] Performance Testing

[0044] Mechanical properties testing

[0045] The mechanical properties of fiber filaments include tensile strength and elongation at break. The tensile strength is tested on the fiber filaments according to GB / T14344-2022 "Test method for tensile properties of chemical fiber filaments", and the average value is obtained by multiple tests. The unit of tensile strength of the filament fiber is: cN / dtex.

[0046] The elongation at break of the fiber filament was measured according to GB / T3916-2013 “Textiles — Yarn in Packages — Determination of Breaking Strength and Elongation at Break of Single Yarn”, and the elongation at break of the prepared regenerated polyester fiber filament was tested using a YF020 electronic single yarn strength meter.

[0047] Wear resistance

[0048] The wear resistance of regenerated polyester fiber is one of the reference standards for fiber performance. According to the test method in FZ / T 01121-2014 "Test Method for Abrasion Resistance of Textiles - Flat Abrasion Test", the regenerated polyester fiber filaments prepared in the Examples and Comparative Examples were spun and humidified under standard atmospheric temperature of 20°C and relative humidity of 65%. After humidity conditioning, circular specimens with an area of ​​100 cm were cut and tested for abrasion resistance. Under a specified friction pressure, the specimen, mounted on the fixture of the flat abrasion tester, was inflated and subjected to reciprocating plane friction with an abrasive (NO.600 water-repellent sandpaper). The specimen fixture was allowed to rotate freely about its axis perpendicular to the horizontal plane. The number of frictions until the specimen was damaged was recorded. The greater the number of frictions, the better the wear resistance of the fabric, that is, the better the wear resistance of the fiber.

[0049] Degradable properties

[0050] We tested the biodegradability of recycled polyester filament fibers from the soil landfill example and the comparative example. Degradable fibers, when buried in soil, generate and release CO2, and the degradation percentage is calculated based on the amount of CO2 released. Therefore, simply quantifying the released CO2 can measure the soil's ability to degrade biodegradable samples and their degradability in soil. To this end, we customized the following performance testing protocol:

[0051] To sample, 100 mg of regenerated polyester fiber was mixed with 200 g of sample soil and placed in a 500 mL wide-mouth bottle. A small beaker containing 10 mL of a known concentration of NaOH solution was placed on top of the soil and the bottle was sealed with a rubber stopper. After incubating at 30°C for 21 days, the rubber stopper was removed and a certain amount of NaOH solution was removed from the beaker. This solution was then titrated with a known concentration of HCl solution. The CO2 released was measured based on the amount of HCl solution consumed, indicating the biodegradability of the biodegradable regenerated polyester fiber in the soil. The degradation percentage of the regenerated polyester fiber was then calculated.

[0052] Examples 1-3

[0053] First, prepare the raw materials. The components listed in Table 1 are weighed by weight: recycled polyester, polyester waste, a combined biodegradable additive, an inorganic powder filler, a swelling agent, and a mixed coupling agent. The raw materials are uniformly mixed and then heated until melted to produce a recycled melt. The recycled melt is then transported to a spinning machine for extrusion and spinning to produce regenerated polyester staple fibers.

[0054] The melt extrusion temperature is 220-230° C., the spinning speed is 1000-1500 m / min, and the fineness of the regenerated polyester fiber filament is 100-120 dtex.

[0055] Furthermore, the recycled polyester comprises the following processing steps:

[0056] A1. Collect waste plastics, remove large debris, and sort them by type and color. The sorted waste plastics are crushed into 3-5 cm particles. The crushed waste plastic particles are sent to a cleaning tank, where cleaning water is added to clean the waste plastic particles. After cleaning, the waste plastic particles are removed and drained to obtain polyester waste.

[0057] A2, the polyester waste, the catalyst zinc acetate and the alcoholysis agent ethylene glycol are mixed and stirred uniformly to obtain a mixed solution, the mixed solution is heated under nitrogen protection to perform a depolymerization reaction to obtain an alcoholysis solution, and the mixture is kept warm for standby use;

[0058] A3, filtering the alcoholysis solution twice, discarding the filter residue, and then adding methanol, a decolorizing agent, and antimony trioxide to the filtered liquid for polycondensation to obtain regenerated polyester;

[0059] Among them, the decolorizing agent is Dove decolorizing agent.

[0060] Furthermore, in step A2, the temperature of the heated mixed solution is 190-200° C., and the heating time of the reaction solution is 3-5 hours; in step A3, the polycondensation reaction temperature is 220-240° C., and the reaction time is 2-3 hours.

[0061] Furthermore, in step A3, the secondary filtration includes primary filtration and secondary filtration:

[0062] The first stage filtration adopts a mesh filter, the first stage filtration pressure is 0.1-0.4MPa, the first stage filtration precision is 10-500mm, the second stage filtration pressure is 0.1-0.4MPa, the second stage filtration precision is 10-100mm;

[0063] The secondary filtration uses a plate and frame filter, with a first-stage filtration pressure of 0.2-0.4 MPa and a first-stage filtration precision of 0.1-5 mm, and a second-stage filtration pressure of 0.2-0.4 MPa and a second-stage filtration precision of 10-100 mm. The material ratios of each embodiment are shown in Table 1 below.

[0064] Table 1 Material usage ratio

[0065]

[0066] *A is modified regenerated silk fibroin; B is cellulose carbamate; C is an isocyanate silane coupling agent; D is lithium silicate

[0067] Comparative Examples 1-7

[0068] The components shown in Table 1 were weighed in percentage by weight: recycled polyester, polyester waste, combined degradable additive, inorganic powder filler, swelling agent, mixed coupling agent and other raw materials. Other steps were carried out with reference to Example 1.

[0069] The regenerated fibers of the embodiment and the comparative example were subjected to performance tests according to relevant standards. The relevant test comparisons are shown in Table 2.

[0070] Table 2 Performance test results comparison analysis table

[0071]

[0072] From the analysis of the comparison results of Table 1 to Table 2 above, it can be seen that the combined degradable additive used in the present invention has the effect of improving the degradability of regenerated fiber. The mass ratio of modified regenerated silk fibroin and cellulose carbamate in the combined degradable additive is (7.8-9.2): (0.2-0.8). At this ratio, the combined additive can reach the optimal combination. Too much modified regenerated silk fibroin will affect the mechanical properties of the material, so cellulose carbamate is used to fill it under the limit value during the test; too little modified regenerated silk fibroin will affect the degradable properties of regenerated fiber. Under this condition, using cellulose carbamate to fill it will cause lumps. Therefore, the optimal combination of the present invention is that the mass ratio of modified regenerated silk fibroin and cellulose carbamate is (7.8-9.2): (0.2-0.8). Other factors of the regenerated fiber of the present invention have little effect on the degradable properties of the fiber.

[0073] Modified boron nitride has the advantage of a filler structure in terms of mechanical and wear resistance. Boron nitride plays a significant role in mechanical load-bearing, and its absence significantly impacts the fiber's wear and mechanical properties. Furthermore, the amphiphilic properties of graphene in modified boron nitride can affect the material's interfacial bonding, further impacting tensile strength and wear resistance. Among combined biodegradable additives, modified regenerated silk fibroin uses MXene for material modification, which has a second-highest impact on the fiber's mechanical and wear resistance, after modified boron nitride. The mechanical effects of mixed coupling agents, isocyanate silane coupling agents, and lithium silicate on fibers are primarily manifested in the following ways: Isocyanate silane coupling agents contain isocyanate groups, which consume moisture from the raw materials or air. This not only reduces the drying steps required for the raw materials and accelerates the process, but also reduces the stress concentration caused by moisture after the material is formed. Furthermore, the use of coupling agents addresses the issue of poor compatibility between fillers and other components, reducing the number of defects in regenerated polyester fibers and enhancing the fiber's mechanical properties. Lithium silicate absorbs carbon dioxide generated by the reaction of isocyanate groups with water, reducing the impact of bubbles during molding. Isocyanate silane coupling agents and lithium silicate exhibit a synergistic reinforcing effect; the absence of coupling agents in lithium silicate can lead to interfacial compatibility issues. The absence of lithium silicate in isocyanate silane coupling agents can also lead to stress concentration caused by bubbles. Therefore, a mixed coupling agent formulation is used to meet the mechanical requirements of regenerated fibers. Moreover, the coupling agent and the graphene in the modified boron nitride both contribute to interfacial compatibility; the mixed coupling agent system and the combined degradable additive also contain the same elements, reducing the problem of foreign matter incompatibility between the components.

[0074] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made 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 claims.

Claims

1. A regenerated polyester fiber, characterized in that: The regenerated polyester fiber is obtained by extrusion spinning of a regenerated melt, which is obtained by melting a regenerated mixed material. The regenerated mixed material includes the following raw material components in parts by weight: 45-55 parts of recycled polyester; 20-25 parts of polyester waste; 16-20 parts of combined biodegradable additives; 4-5 parts of inorganic powder filler; 2-5 parts of swelling agent; Mix 1-5 parts of coupling agent.

2. The regenerated polyester fiber according to claim 1, characterized in that: The recycled polyester comprises the following processing steps: A1. Collect waste plastics, remove large debris, and sort them by type and color. The sorted waste plastics are crushed into 3-5 cm particles. The crushed waste plastic particles are sent to a cleaning tank, where cleaning water is added to clean the waste plastic particles. After cleaning, the waste plastic particles are removed and drained to obtain polyester waste. A2, the polyester waste, the catalyst zinc acetate and the alcoholysis agent ethylene glycol are mixed and stirred uniformly to obtain a mixed solution, the mixed solution is heated under nitrogen protection to perform a depolymerization reaction to obtain an alcoholysis solution, and the mixture is kept warm for standby use; A3, filtering the alcoholysis solution twice, discarding the filter residue, and then adding methanol, a decolorizing agent, and antimony trioxide to the filtered liquid for polycondensation to obtain regenerated polyester; Among them, the decolorizing agent is one of Dove decolorizing agent, Cetaphil decolorizing agent, and Yashuang decolorizing agent.

3. The regenerated polyester fiber according to claim 2, characterized in that: In step A2, the temperature of the mixed solution is 190-200° C., and the heating time of the reaction solution is 3-5 hours; in step A3, the polycondensation reaction temperature is 220-240° C., and the reaction time is 2-3 hours.

4. The regenerated polyester fiber according to claim 2, characterized in that: In step A3, the secondary filtration includes primary filtration and secondary filtration: The first stage filtration adopts a mesh filter, the first stage filtration pressure is 0.1-0.4MPa, the first stage filtration precision is 10-500mm, the second stage filtration pressure is 0.1-0.4MPa, the second stage filtration precision is 10-100mm; The secondary filtration uses a plate and frame filter. The first stage filtration pressure is 0.2-0.4MPa, the first stage filtration accuracy is 0.1-5mm, the second stage filtration pressure is 0.2-0.4MPa, and the second stage filtration accuracy is 10-100mm.

5. The regenerated polyester fiber according to claim 1, characterized in that: The combined degradable additive comprises modified regenerated silk fibroin and cellulose carbamate, and the mass ratio of the modified regenerated silk fibroin to the cellulose carbamate is (7.8-9.2):(0.2-0.8).

6. The regenerated polyester fiber according to claim 1, characterized in that: The swelling agent is dimethyl sulfoxide; and the inorganic powder filler is modified boron nitride.

7. The regenerated polyester fiber according to claim 1, characterized in that: The mixed coupling agent is a mixture of an isocyanate silane coupling agent and lithium silicate, and the mass ratio of the two is (0.8-4): (0.2-1).

8. A method for preparing the regenerated polyester fiber according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Evenly mixing recycled polyester, polyester waste, a combined degradable additive, an inorganic powder filler, a swelling agent, and a mixed coupling agent according to a proportion to obtain a mixture, and heating the mixture until it is melted to obtain a recycled melt; S2. The regenerated melt is transported to a spinning device for extrusion spinning to obtain regenerated polyester staple fibers.

9. The preparation method according to claim 8, wherein In step S2, the melt extrusion temperature is 220-230°C, the spinning speed is 1000-1500 m / min, and the fineness of the regenerated polyester fiber filament is 100-120 dtex.

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