Preparation method of matte regenerated PET clothing fastener based on waste textile recovery

Abstract

The invention provides a preparation method of a matte regenerated PET clothing fastener based on waste textile recovery, and relates to the technical field of high-end clothing accessory manufacturing, and the preparation method comprises the following steps: S1, high-valued recovery of polyester from waste textiles; s2, composite modification of recycled PET; s3, performing injection molding on a primary fastener blank; s4, carrying out micro-etching treatment on the surface of the fastener primary blank; wherein the high-valued polyester recovery of the waste textiles comprises the steps of NIR sorting, wet crushing, enzymolysis purification, supercritical COextraction, solid-phase tackifying and extrusion granulation. Through NIR sorting, wet crushing, enzymolysis purification, supercritical COextraction, solid-phase tackifying and extrusion granulation, nano-composite modification and surface micro-etching technologies, matting and high performance of the regenerated PET fastener are realized, the product has high-end texture and environmental protection properties, a'clothing-to-clothing 'closed-loop green cycle is realized, and the product has a good market prospect. And green upgrading and sustainable development of the clothing industry are accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of high-end clothing accessories manufacturing, and in particular to a method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles. Background Art

[0002] The use of recycled PET in clothing is becoming increasingly popular. According to the Ellen MacArthur Foundation's "Circular Economy 100" report, in 2023, the proportion of global recycled PET raw materials coming from waste textiles will be less than 5%. In the future, textile recycling of PET may become a key pillar of carbon reduction in the industry, with broad long-term prospects. PET (polyethylene terephthalate) However, existing technologies face several bottlenecks: Sorting is difficult during the textile waste recycling process. Furthermore, since most textile waste is made of blended materials (such as polyester-cotton, polyester-viscose, polyester-ammonia, and polyester-wool), efficient separation is difficult. Furthermore, impurities such as dyes and additives must be processed. Furthermore, the impact strength of recycled PET from textile waste is less than 5kJ / m² due to molecular chain breakage, resulting in poor toughness. Furthermore, recycled PET injection molded products generally exhibit a high gloss, making it difficult to meet the market demand for matte fasteners. Therefore, we have addressed this issue by proposing a method for preparing matte recycled PET clothing fasteners based on recycled textile waste. Summary of the Invention

[0003] The present invention provides a method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles, comprising the following steps: S1, high-value recycling of polyester from waste textiles; S2, recycled PET composite modification; S3, injection molding fastener embryo; S4, micro-etching treatment on the surface of the fastener blank; Among them, the high-value recovery of polyester from waste textiles includes: NIR sorting, wet crushing, enzymatic purification, supercritical CO2 extraction, solid phase viscosity increasing + extrusion granulation.

[0004] As the preferred technical solution of this application, NIR sorting includes: identifying the material of waste textiles by NIR sorting technology, selecting polyester fabrics, NIR sorting technology judging the polyester material by polyester characteristic spectrum, and separating polyester fabrics by air flow nozzle or robotic arm; The wet crushing process includes tearing the sorted polyester fabric into pieces by wet crushing. First, the sorted large pieces of polyester fabric are cut into small pieces of polyester fabric suitable for crushing. Then, a wet shredder or a hammer crusher is used to tear the small pieces of polyester fabric into pieces.

[0005] As a preferred technical solution of the present application, the enzymatic hydrolysis purification includes: enzymatic hydrolysis purification using cellulase to decompose the cellulose fiber components in the polyester fabric fragments, and then using protease to decompose the animal fiber components in the polyester fabric fragments to achieve separation of the blended components.

[0006] As the preferred technical solution of the present application, the supercritical CO2 extraction includes: using supercritical CO2 to dissolve and remove organic pollutants from polyester fabrics; first, the polyester fabric fragments after enzymatic hydrolysis and purification are placed in an extraction kettle, the CO2 is pressurized to 15MPa by a high-pressure pump, and heated to 40°C to reach a supercritical state; then the supercritical CO2 fluid enters the extraction kettle and contacts the polyester fabric fragments. The high diffusivity and solubility of CO2 enable it to quickly penetrate into the fiber, dissolve and carry organic pollutants; finally, the CO2 fluid carrying organic pollutants enters the separation kettle, and by reducing the pressure to below 5MPa, the CO2 is converted from a supercritical state to a gaseous state, the solubility capacity drops sharply, the organic pollutants are precipitated and deposited at the bottom of the separation kettle, the decolorization and purification of the polyester fabric fragments is completed, and the color of the polyester fabric is restored to its original white color.

[0007] As the preferred technical solution of the present application, the solid-phase viscosification + extrusion granulation includes: integrating solid-phase viscosification and extrusion granulation to convert waste polyester fabric into high-purity recycled PET particles; first, the decolorized polyester fabric fragments are placed in a fluidized bed reactor, and the terminal hydroxyl (-OH) and carboxyl (-COOH) of the recycled PET molecular chain are promoted to condense in a high-purity nitrogen environment and solid phase state to release water molecules and extend the molecular chain; then, the product is transported to the extruder for melting under nitrogen protection, and small molecular impurities are removed through vacuum devolatilization and high-efficiency filtration; finally, high-purity white recycled PET particles are obtained by pelletizing.

[0008] As the preferred technical solution of the present application, the recycled PET composite modification includes: mixing recycled PET particles, nano-silica matting agent, POE toughening agent, antioxidant and lubricant according to mass percentage, melt blending and granulating through a twin-screw extruder to obtain composite recycled PET particles.

[0009] As the preferred technical solution of this application, the mass percentages of the composite recycled PET material are as follows: Recycled PET pellets: 80-92%; Nano-silica matte agent: 3-8%; POE toughening agent: 5-12%; 1010+168 compound antioxidant: 0.5-1.5%; PETS lubricant: 0.5-1.5%.

[0010] As a preferred technical solution of the present application, the injection molding of the fastener blank comprises: matching the color of the composite recycled PET particles, placing them in an injection molding machine, adopting segmented temperature control, high pressure and low speed injection molding, and demolding to obtain the recycled PET fastener blank; The barrel temperature of the segmented temperature control is: Zone I 210℃, Zone II 225℃, Zone III 230℃, and the mold temperature is 60-80℃; The high-pressure, low-speed injection molding has an injection pressure of 80-100 MPa, a holding time of 8-12 seconds, and a cooling time of 15-20 seconds.

[0011] As a preferred technical solution of the present application, the micro-etching treatment of the surface of the fastener embryo includes: immersing the recycled PET fastener embryo in a low concentration hydrofluoric acid solution for etching to obtain a matte recycled PET fastener; the concentration of the hydrofluoric acid etching solution is 0.3-0.7%, the etching temperature is 10-30°C, and the recycled PET fastener embryo is immersed in the hydrofluoric acid solution for etching for 3-8 minutes.

[0012] As the preferred technical solution of this application, the matte recycled PET fastener is based on the recycling of waste textiles, is homologous to polyester, and is used in clothing as a clothing accessory.

[0013] Compared with the prior art, the present invention has the following beneficial effects: In the scheme of this application: The present invention achieves matte and high-performance of recycled PET fasteners through NIR sorting, wet crushing, enzymatic purification, supercritical CO2 extraction, solid-phase viscosity enhancement + extrusion granulation, nano-composite modification and surface micro-etching technology. The product has both high-end texture and environmentally friendly properties, realizing a "garment to garment" closed-loop green cycle, and accelerating the green upgrade and sustainable development of the clothing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A flow chart of the method for preparing matte recycled PET clothing fasteners based on waste textile recycling provided in this application; Figure 2 Flow chart for high-value polyester recycling from waste textiles provided for this application; Figure 3 This is a schematic diagram of the mass percentage of the composite recycled PET material provided in this application. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0016] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein may be combined with each other.

[0017] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0018] Example 1, please refer to Figure 1-Figure 3 A method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles comprises the following steps: S1, high-value recycling of polyester from waste textiles; S2, recycled PET composite modification; S3, injection molding fastener embryo; S4. Micro-etching treatment on the surface of the fastener blank.

[0019] Among them, the high-value recycling of polyester from waste textiles includes: NIR sorting, wet crushing, enzymatic purification, supercritical CO2 extraction, solid phase thickening + extrusion granulation.

[0020] Furthermore, NIR sorting includes: using NIR sorting technology to identify the material of waste textiles and select polyester fabrics. NIR sorting technology determines the polyester material through polyester characteristic spectrum and separates the polyester fabrics through air nozzles or robotic arms. NIR sorting can identify blended materials with polyester content as low as 5%, and can increase the purity of polyester fabric sorting to over 95%. NIR sorting technology has the advantages of high precision, high efficiency, and no need for chemical treatment. It is more environmentally friendly than traditional manual sorting and chemical sorting. Wet shredding involves tearing the sorted polyester fabric into pieces through wet shredding. First, the sorted large pieces of polyester fabric are cut into small pieces suitable for shredding, with the size of the small pieces being less than 20cm². A wet shredder or hammer crusher is then used to tear the small pieces into pieces. The wet shredding process uses a hydraulic sorting system to remove surface contaminants, lightweight plastics, and other impurities. Wet shredding breaks the polyester fabric into pieces in a liquid environment, avoiding the high-temperature damage and dust pollution associated with dry shredding. Furthermore, enzymatic purification includes: enzymatic purification uses cellulase to decompose the cellulose fiber components in polyester fabric fragments, and then uses protease to decompose the animal fiber components in polyester fabric fragments, such as wool, to achieve the separation of blended components. Cellulose fiber components include cotton, viscose, linen, modal, etc. According to statistics in 2023: Polyester accounts for about 55% of global fiber consumption, of which about 50% of polyester is used in clothing in the form of blends; among polyester blended types, 40% is polyester + cotton, 30% is polyester + spandex, 15% is polyester + viscose fiber, 8% is polyester + wool, and 7% is other blended types (such as polyester + linen, modal, recycled fiber, etc.); therefore, polyester fabrics after NIR sorting usually contain a certain proportion of blended components such as cotton, spandex, viscose, wool, linen, modal, etc. , which needs further separation and purification; considering that cotton, viscose, linen, and modal are all cellulose fibers and account for the majority of the blended components, they should be separated from polyester fabrics; secondly, although wool only accounts for a very small proportion of the blended materials, it is not resistant to high temperatures and is easily carbonized during the recycling process, affecting the performance of the recycled PET, and also needs to be separated from the polyester fabric; spandex is a polyurethane fiber, and its chemical composition is polyurethane elastomer, which can be retained as a reinforcing and modified material for composite recycled PET; after enzymatic hydrolysis and purification, polyester and spandex remain intact due to their enzyme resistance, so the purity of polyester is increased to more than 98%, and less than 2% is residual chemical fiber components such as spandex from enzymatic hydrolysis; enzymatic hydrolysis and purification efficiently separates blended components, and its operating temperature is 40-60°C, which reduces energy consumption by 40-60% compared to traditional acid-base hydrolysis chemical methods; enzymes are biodegradable, and the COD (chemical oxygen demand) of wastewater is reduced by 50% compared to traditional processes; Furthermore, supercritical CO2 extraction includes: using supercritical CO2 to dissolve and remove organic pollutants from polyester fabrics, such as dyes and greases; first, placing the enzymatically purified polyester fabric fragments in an extraction kettle, pressurizing the CO2 to 15 MPa through a high-pressure pump, and heating it to 40°C to achieve a supercritical state; then, supercritical CO2 fluid enters the extraction kettle and comes into contact with the polyester fabric fragments. The high diffusivity and solubility of CO2 allow it to quickly penetrate into the fibers, dissolving and carrying organic pollutants; finally, the CO2 fluid carrying organic pollutants enters the separation kettle, and by reducing the pressure to below 5 MPa, the CO2 is converted from a supercritical state to a gaseous state, and the solubility drops sharply. The organic pollutants are precipitated and deposited at the bottom of the separation kettle, completing the decolorization and purification of the polyester fabric fragments, and restoring the color of the polyester fabric to its original white color. Supercritical CO2 extraction technology utilizes the high diffusivity and solubility of CO2 in a supercritical state to efficiently remove dyes and grease from waste polyester fabrics, maintaining the integrity of the PET substrate. At the same time, decolorization and purification to a natural white color facilitates the subsequent color matching of recycled PET materials, expanding their application range. Furthermore, CO2 is non-toxic, residue-free, and recyclable, avoiding environmental pollution caused by organic solvents.

[0021] Furthermore, solid-phase viscosification plus extrusion granulation involves integrating solid-phase viscosification with extrusion granulation to convert waste polyester fabric into high-purity recycled PET pellets. First, the decolorized polyester fabric fragments are placed in a fluidized bed reactor. In a high-purity nitrogen environment and in a solid-phase state, the hydroxyl (-OH) and carboxyl (-COOH) condensation reactions at the terminal ends of the recycled PET molecular chains are promoted, releasing water molecules and extending the molecular chains, thereby increasing the average molecular weight and intrinsic viscosity (IV) of the recycled PET. The fragments are then transported to an extruder under nitrogen protection for melting. Vacuum devolatilization and high-efficiency filtration remove small molecular weight impurities, further increasing the purity of the recycled PET. Finally, pelletization produces high-purity, natural-white recycled PET pellets with an intrinsic viscosity (IV) of ≥0.80 dL / g. The combination of solid-phase viscosification and extrusion granulation reduces the need for intermediate cooling and reheating steps, reducing energy consumption by 20–30%. Furthermore, the dual effects of molecular chain repair and melt purification significantly enhance the performance and added value of the recycled PET. Therefore, solid-phase viscosification and extrusion granulation are both environmentally friendly and economical.

[0022] Furthermore, the composite modification of recycled PET includes: mixing recycled PET particles, nano-silica matting agent, POE toughening agent, antioxidant and lubricant according to mass percentage, melt-blending and granulating through a twin-screw extruder to obtain composite recycled PET particles; the set temperature of the twin-screw extruder is: 230°C in zone 1, 240°C in zone 2, 250°C in zone 3, and the screw speed is 200rpm.

[0023] Furthermore, the mass percentages of the composite recycled PET material are as follows: Recycled PET particles: 80%; Nano-silica matte agent: 8%; POE toughening agent: 10.5%; 1010+168 compound antioxidant: 1%; PETS lubricant: 0.5%; Specifically, the recycled PET particles are the matrix of the composite recycled PET material, which comes from the environmentally friendly recycling of waste polyester textiles. The recycled PET intrinsic viscosity (IV value) is ≥0.80dL / g, and the recycled PET purity is ≥98%.

[0024] Specifically, the nano-silica matting agent has a porous three-dimensional network structure and a high specific surface area, which can effectively scatter light and reduce surface gloss, thereby achieving a matte effect of the composite recycled PET material; at the same time, the nano-silica is a rigid nanoparticle, which is uniformly dispersed in the recycled PET matrix, and can limit the movement of the recycled PET molecular chain through the "pinning effect", enhance the interfacial bonding force, and act as a nucleating agent, thereby improving the crystallinity and heat resistance of the composite recycled PET material; in order to avoid agglomeration of the nano-silica matting agent, the nano-silica is pretreated with a silane coupling agent, and the coupling agent is coated on the surface by high-speed stirring; the silane coupling agent is preferably KH550, and the amount used is 5% of the mass of the nano-silica matting agent; the nano-silica matting agent is surface activated and modified by the silane coupling agent KH550, which can significantly improve the dispersibility and interfacial bonding in the composite recycled PET material.

[0025] Specifically, POE toughening agents are ethylene-octene copolymers. Their molecular chains are composed of flexible random ethylene-octene copolymer segments and crystalline polyethylene segments, resulting in rubber-like elasticity. They significantly improve the notched impact strength of PET substrates while minimizing the impact on the rigidity and strength of the substrate, outperforming many traditional rubber-based toughening agents.

[0026] Specifically, the 1010+168 compound antioxidant can synergistically enhance efficiency and form a dual defense mechanism, which can inhibit the thermal oxidative degradation process of recycled PET materials, delay their aging, increase their service life, and maintain stable performance; the compounding ratio of the 1010+168 compound antioxidant is 1:1.

[0027] Specifically, the PETS lubricant is pentaerythritol stearate, which can achieve synergistic lubrication of the internal and external parts of the composite recycled PET material, and a smaller amount of addition can achieve the lubrication effect. The PETS lubricant can also promote the uniform dispersion of the nano-silica matting agent and has good compatibility with recycled PET.

[0028] Furthermore, the injection molding of the fastener blank includes: matching the color of the composite recycled PET particles, placing them in an injection molding machine, adopting segmented temperature control and high-pressure low-speed injection molding, and demolding to obtain the recycled PET fastener blank; Specifically, the barrel temperature of the segmented temperature control is: Zone I 210°C, Zone II 225°C, Zone III 230°C, and the mold temperature is 70°C; Specifically, the high-pressure, low-speed injection molding process has an injection pressure of 90 MPa, a holding time of 10 s, and a cooling time of 15-20 s.

[0029] Furthermore, the micro-etching treatment of the surface of the fastener embryo includes: immersing the recycled PET fastener embryo in a low-concentration hydrofluoric acid solution for etching to obtain a matte recycled PET fastener.

[0030] The concentration of the hydrofluoric acid etching solution is 0.35%, and the etching temperature is 10-30°C. The recycled PET fastener embryo is immersed in the hydrofluoric acid solution for etching for 5 minutes. The recycled PET substrate itself has a strong tolerance to low-concentration hydrofluoric acid etching solution and is not easily corroded. Nano-silicon dioxide is evenly dispersed in the composite recycled PET material. The low-concentration hydrofluoric acid etching solution will chemically react with silicon dioxide. The reaction formula is: SiO2+6HF→H2SiF+2H2O. As a result, the nano-silicon dioxide particles on the surface of the composite recycled PET material are dissolved, forming micron-sized pits on the surface, enhancing light scattering, and thus achieving a matte recycled PET fastener.

[0031] Furthermore, matte recycled PET fasteners are based on the recycling of waste textiles and have the same origin as polyester. They are used in clothing as clothing accessories, realizing a closed-loop green cycle from "clothing to clothing" and accelerating the green upgrade and sustainable development of the clothing industry.

[0032] Example 2, the preparation method of matte recycled PET clothing fasteners based on waste textile recycling provided in Example 1 is further optimized. Specifically, the POE toughening agent is POE-g-MAH, that is, maleic anhydride grafted ethylene-octene copolymer, wherein POE is used as the elastomer dispersed phase, and absorbs impact energy through the "island structure", plays a toughening role, and improves the impact strength of recycled PET; MAH is grafted onto the POE main chain to give the originally non-polar POE a certain polarity, enhance interfacial bonding, prevent phase separation, and improve the POE elastomer and recycled The interface compatibility between the residual polyurethane elastomer and the recycled PET is improved, so that it is more evenly dispersed in the composite material; in addition, during the melt blending process, the anhydride group (-MAH) of POE-g-MAH undergoes esterification or ring-opening reaction with the terminal hydroxyl group (-OH) or terminal carboxyl group (-COOH) of the recycled PET to form an ester bond or a carboxylate ester bond. This chemical bonding enhances the interfacial adhesion between POE and the recycled PET. The mass percentage of the POE-g-MAH toughening agent in the composite recycled PET material is 5-12%, and its grafting rate is preferably 1%.

[0033] Example 3, the preparation method of matte recycled PET clothing fasteners based on waste textile recycling provided in Example 1 is further optimized. Specifically, the POE toughening agent can also be POE-g-GMA, that is, glycidyl methacrylate (GMA) grafted ethylene-octene copolymer, wherein POE serves as the elastomer dispersed phase, absorbs impact energy through the "island structure", plays a toughening role, and improves the impact strength of the recycled PET; GMA has high reactivity, and polar groups are introduced into the POE molecular chain through the grafting reaction, thereby enhancing the interfacial binding ability, preventing phase separation, and improving the interfacial compatibility of the POE elastomer and the recycled residual polyurethane elastomer with the recycled PET, so that they are more evenly dispersed in the composite material; in addition, during the melt blending process, the epoxy group in GMA undergoes a ring-opening reaction with the terminal hydroxyl group (-OH) or terminal carboxyl group (-COOH) of the recycled PET to form an ester bond. This chemical bonding enhances the interfacial adhesion between POE and the recycled PET. The mass percentage of the POE-g-GMA toughening agent in the composite recycled PET material is 5-12%, and its grafting rate is preferably 2%.

[0034] The fastener obtained in Example 1 has a surface gloss of 13GU (measured at a 60° angle), an impact strength of 9.2 kJ / m², and a heat deformation temperature HDT of 105°C.

[0035] In Example 4, the formula was adjusted to 85% recycled PET particles, 5% nano-silica matting agent (surface treated with silane coupling agent KH550), and 8.5% POE-g-MAH toughening agent. The remaining ingredients were the same as in Example 1. The resulting fastener had a gloss of 16 GU (measured at a 60° angle), an impact strength of 8.5 kJ / m², and a heat deformation temperature (HDT) of 102°C.

[0036] In Example 5, the formula was adjusted to 90% recycled PET particles, 3% nano-silica matting agent (surface treated with silane coupling agent KH550), and 5.5% POE-g-MAH toughening agent. The remaining ingredients were the same as in Example 1. The resulting fastener had a gloss of 18 GU (measured at a 60° angle), an impact strength of 7.8 kJ / m², and a heat deformation temperature (HDT) of 100°C.

[0037] Example 6. This example is a comparative example. No nano-silica matting agent and POE-g-MAH toughening agent are added. The formula is 98.5% recycled PET particles, 1% 1010+168 compound antioxidant, and 0.5% PETS lubricant, which are blended and granulated. Injection molding parameters: Zone I 210°C, Zone II 225°C, Zone III 230°C, mold temperature 70°C, injection pressure 90MPa, holding pressure 10s; etching treatment: hydrofluoric acid concentration 0.5%, room temperature treatment time 5min; the obtained fastener has a surface gloss of 22GU (measured at a 60° angle), an impact strength of 5.0kJ / m², and a heat deformation temperature HDT of 86°C.

[0038] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned specific embodiments, or to make equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the present invention specification and drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles, characterized in that: The following steps are involved: S1, high-value recycling of polyester from waste textiles; S2, recycled PET composite modification; S3, injection molding fastener embryo; S4, micro-etching treatment on the surface of the fastener blank; Among them, the high-value recovery of polyester from waste textiles includes: NIR sorting, wet crushing, enzymatic purification, supercritical CO2 extraction, solid phase viscosity increasing + extrusion granulation.

2. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 1, characterized in that: NIR sorting includes: using NIR sorting technology to identify the material of waste textiles and select polyester fabrics. NIR sorting technology determines the polyester material through polyester characteristic spectrum and separates the polyester fabrics through air nozzles or robotic arms; The wet crushing process includes tearing the sorted polyester fabric into pieces by wet crushing. First, the sorted large pieces of polyester fabric are cut into small pieces of polyester fabric suitable for crushing. Then, a wet shredder or a hammer crusher is used to tear the small pieces of polyester fabric into pieces.

3. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 2, characterized in that: The enzymatic purification comprises: decomposing the cellulose fiber components in the polyester fabric fragments with cellulase, and then decomposing the animal fiber components in the polyester fabric fragments with protease, so as to separate the blended components.

4. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 3, characterized in that: The supercritical CO2 extraction includes: using supercritical CO2 to dissolve and remove organic pollutants from polyester fabric; first, placing the polyester fabric fragments after enzymatic hydrolysis and purification in an extraction kettle, pressurizing the CO2 to 15MPa by a high-pressure pump, and heating it to 40°C to achieve a supercritical state; then, supercritical CO2 fluid enters the extraction kettle and contacts the polyester fabric fragments. The high diffusivity and solubility of CO2 enable it to quickly penetrate into the fibers, dissolve and carry the organic pollutants; finally, the CO2 fluid carrying the organic pollutants enters a separation kettle, and by reducing the pressure to below 5MPa, the CO2 is converted from a supercritical state to a gaseous state, the solubility ability is sharply reduced, and the organic pollutants are precipitated and deposited at the bottom of the separation kettle, thereby completing the decolorization and purification of the polyester fabric fragments and restoring the color of the polyester fabric to its original white color.

5. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 4, characterized in that: The solid-phase viscosification + extrusion granulation method includes: integrating solid-phase viscosification and extrusion granulation to convert waste polyester fabric into high-purity recycled PET particles. First, the decolorized polyester fabric fragments are placed in a fluidized bed reactor, and in a high-purity nitrogen environment and in a solid phase, the hydroxyl (-OH) and carboxyl (-COOH) groups at the terminal ends of the recycled PET molecular chains are promoted to condense, releasing water molecules and extending the molecular chains. Then, the fragments are transported to an extruder under nitrogen protection for melting, and small molecular impurities are removed through vacuum devolatilization and high-efficiency filtration. Finally, the fragments are pelletized to obtain high-purity, natural white recycled PET particles.

6. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 5, characterized in that: The recycled PET composite modification comprises: mixing recycled PET particles, nano-silica matting agent, POE toughening agent, antioxidant and lubricant according to mass percentage, and melt-blending and granulating through a twin-screw extruder to obtain composite recycled PET particles.

7. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 6, characterized in that: The mass percentages of the composite recycled PET materials are as follows: Recycled PET pellets: 80-92%; Nano-silica matte agent: 3-8%; POE toughening agent: 5-12%; 1010+168 compound antioxidant: 0.5-1.5%; PETS lubricant: 0.5-1.5%.

8. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 6, characterized in that: The injection molding of the fastener blank comprises: matching the colors of the composite recycled PET particles, placing them in an injection molding machine, adopting segmented temperature control, high pressure and low speed injection molding, and demolding to obtain the recycled PET fastener blank; The barrel temperature of the segmented temperature control is: Zone I 210℃, Zone II 225℃, Zone III 230℃, and the mold temperature is 60-80℃; The high-pressure, low-speed injection molding has an injection pressure of 80-100 MPa, a holding time of 8-12 seconds, and a cooling time of 15-20 seconds.

9. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 8, characterized in that: The micro-etching treatment of the surface of the fastener embryo includes: immersing the recycled PET fastener embryo in a low-concentration hydrofluoric acid solution for etching to obtain a matte recycled PET fastener; the concentration of the hydrofluoric acid etching solution is 0.3-0.7%, the etching temperature is (10-30°C), and the recycled PET fastener embryo is immersed in the hydrofluoric acid solution for etching for 3-8 minutes.

10. The method for preparing matte recycled PET clothing fasteners based on recycling of waste textiles according to claim 9, characterized in that: The matte recycled PET fastener is based on the recycling of waste textiles, has the same origin as polyester, and is used in clothing as a clothing accessory.

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