Method, product and system for cleaning and recycling waste textiles with carbon dioxide fluid

Abstract

The invention relates to a method, a product and a system for cleaning and recycling waste textiles by using carbon dioxide fluid, which comprises the following steps of: putting an obtained waste fiber net into a pretreatment tank, injecting supercritical carbon dioxide into the pretreatment tank to statically soak the waste fiber net to obtain a soaked fiber net, taking the soaked fiber net out of the pretreatment tank, and drying the soaked fiber net in a drying oven to obtain a finished product. The method comprises the following steps of: soaking a fiber web in the fiber web, feeding the fiber web into an entangling working chamber, ejecting a fluid jet flow formed by supercritical carbon dioxide or subcritical carbon dioxide from top to bottom to the soaked fiber web, penetrating or penetrating the fluid jet flow into the fiber web to entangle fibers in the fiber web, and washing pollutants on the fibers until the fiber web is conveyed out of the entangling working chamber; therefore, the reinforced fiber web is obtained. According to the design, mutual cooperation of cleaning and entanglement can be achieved, the recycling effect is good, water consumption and energy consumption are low, and environment friendliness is achieved.

Description

Technical Field

[0001] This invention relates to a recycling process for waste textiles, belonging to the field of waste textile recycling, and particularly to a method, product, and system for recycling waste textiles by cleaning with carbon dioxide fluid. Background Technology

[0002] Currently, sorting, washing, cutting, or shredding waste textiles to obtain recycled fibers, which are then re-spun into yarn or made into new materials such as nonwoven fabrics, has gradually become an ideal choice in the field of waste textile recycling, achieving resource recycling. This process not only saves resources but also embodies the concept of environmental protection, making it a model of green technology. It is widely applicable to the recycling of waste textiles such as old clothes, automotive interior textiles, household textiles (such as curtains, carpets, and mattresses), and agricultural nonwoven fabrics.

[0003] Nonwoven fabrics, also known as non-woven cloth or non-woven fabrics, refer to fabrics formed directly by bonding fibers without the need for spinning and weaving processes. They are characterized by being breathable, moisture-proof, flame-retardant, lightweight, non-toxic, odorless, biodegradable, and inexpensive. They are widely used in medical protection (such as surgical gowns and masks), industrial filtration, agricultural covering, and have also been extended to sound-absorbing materials, heat-insulating materials, and filling materials.

[0004] To ensure the quality of recycled fibers, it is essential to thoroughly clean the contaminants on them. Simultaneously, to enhance the strength of the nonwoven fabric, the fiber web formed by recycled fibers needs to be entangled and reinforced. Existing entanglement reinforcement methods primarily employ hydroentangling, which uses multiple fine water jets generated under high pressure to spray the fiber web. When the water jets pass through the web, they are rebounded by the support curtain and re-entangle. Thus, under the hydraulic action of the high-speed water jets penetrating in different directions, the fibers in the web undergo displacement, interpenetration, and entanglement, thereby reinforcing the fiber web.

[0005] However, the existing cleaning process and entanglement reinforcement process are two independent processes. There is no cooperation between them, and they can only be carried out separately, resulting in low overall recycling efficiency and high cost.

[0006] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects and problems of existing technologies, such as the inability of cleaning and entanglement to cooperate and the poor recycling effect, and to provide a method, product and system for cleaning and recycling waste textiles with carbon dioxide fluid that achieves better recycling effect by having cleaning and entanglement cooperate.

[0008] To achieve the above objectives, the technical solution of the present invention is: A method for recycling waste textiles by cleaning with carbon dioxide fluid, the method comprising the following steps: Step 1, Preparation: Obtain waste fiber mesh; Step 2, Supercritical Cleaning Step: First, place the above-mentioned waste fiber web into the pretreatment tank, then inject supercritical carbon dioxide into the pretreatment tank until the waste fiber web is soaked in supercritical carbon dioxide. Then, control the temperature and pressure in the pretreatment tank so that the waste fiber web is continuously and statically soaked in supercritical carbon dioxide to obtain the soaked fiber web. The third step, entanglement reinforcement step: First, take the soaked fiber web out of the pretreatment tank and send it into the entanglement chamber. Then, use a fluid jet composed of supercritical or subcritical carbon dioxide to spray the soaked fiber web from top to bottom. The fluid jet penetrates or enters the fiber web to entangle the fibers in the fiber web and wash away the contaminants on the fibers until the fiber web is transported out of the entanglement chamber, thereby obtaining the reinforced fiber web.

[0009] In the third step, during the process of the fluid jet penetrating or entering the fiber web to entangle and flush, the temperature and pressure in the entanglement chamber are controlled to be any of the following: The first method: After the fluid jet has penetrated or entered the fiber web, the fluid jet is vaporized in the entanglement chamber to generate gaseous carbon dioxide. The second method: After the fluid jet has penetrated or entered the fiber web, the fluid jet does not vaporize in the entanglement chamber. It only vaporizes when the remaining fluid jet is transported out of the entanglement chamber along with the reinforced fiber web, thus generating gaseous carbon dioxide.

[0010] In the first method, the gaseous carbon dioxide is first collected from the entanglement chamber, then compressed and cooled to re-fluidize it to obtain a fluid jet, which is then injected onto the soaked fiber web for recycling. In the second method, the gaseous carbon dioxide is first collected from outside the entanglement workroom, then compressed and cooled to re-fluidize it into a fluid jet, which is then directed at the soaked fiber web for recycling.

[0011] In the second step, controlling the temperature and pressure in the pretreatment tank means that the temperature is 32-80℃ and the pressure is 7.5-30MPa.

[0012] In the second step, the static soaking time is 5-60 minutes.

[0013] In the second step, the pretreatment tank is connected to a supercritical carbon dioxide circulation pipeline, and an external high-temperature and high-pressure filter is connected to the circulation pipeline; the supercritical carbon dioxide fluid circulates between the pretreatment tank and the high-temperature and high-pressure filter.

[0014] In the third step, the process of taking the soaked fiber web out of the pretreatment tank and sending it into the entanglement chamber is either a pressurized transfer or a transfer after pressure balancing. The pressurized transfer refers to the transfer achieved by connecting the pretreatment tank and the entanglement chamber through a pipeline, during which the system pressure is maintained above 7.5 MPa. The transfer after pressure balancing refers to: reducing the pressure of the pretreatment tank to atmospheric pressure, and then taking out the fiber web and placing it into the entanglement chamber.

[0015] There is a fourth step after the third step, which is: Step 4, Recycling Step: Gaseous carbon dioxide generated in Step 2 and / or Step 3 is collected, compressed and condensed, re-fluidized, and recycled for Step 2 or Step 3.

[0016] In the third step, the fluid jet dynamically impacts the fibers within the entanglement chamber. During this process, a back pressure is maintained within the entanglement chamber. This back pressure is configured to control the phase state and behavior of the fluid jet. The back pressure is 5–25 MPa, and the temperature is 0–50°C, specifically any one or any combination of the following: First pressure condition: The fluid jet is kept in a liquid or supercritical state during the impact process, and phase change vaporization occurs only after the impact is completed; The second pressure condition is to cause the fluid jet to undergo partial or complete phase change and vaporization during the impact process.

[0017] A nonwoven fabric prepared by the above method, the nonwoven fabric being composed of recycled fibers, having no chemical residues inside, and having a three-dimensional entanglement structure formed between the fibers.

[0018] A system for implementing the above-described method of cleaning and recycling waste textiles with carbon dioxide fluid, the system comprising: Pretreatment tank, configured to hold waste fiber web and maintain a supercritical carbon dioxide environment; The entanglement chamber is located downstream of the pretreatment tank and is equipped with nozzles for injecting supercritical or subcritical carbon dioxide fluid jets. A transfer device is provided between the pretreatment tank and the entanglement chamber. The transfer device is configured to realize the pressurized or atmospheric pressure transfer of the soaked fiber web from the pretreatment tank to the entanglement chamber.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention discloses a method, product, and system for cleaning and recycling waste textiles using carbon dioxide fluid. First, the waste textiles are loosened to obtain a waste fiber web. Then, the waste fiber web is placed in supercritical carbon dioxide in a pretreatment tank. The waste fiber web is then continuously and statically immersed in supercritical carbon dioxide to obtain a soaked fiber web. The soaked fiber web is then removed from the pretreatment tank and sent to an entanglement chamber. Multiple jets of supercritical or subcritical carbon dioxide are then ejected from top to bottom onto the soaked fiber web. These jets penetrate or pierce the fiber web to entangle the fibers and wash away contaminants on the fibers until the fiber web is transported outside the entanglement chamber, thus obtaining a reinforced fiber web. The advantages of this design include: First, it can achieve basic cleaning and entanglement reinforcement effects: Supercritical carbon dioxide has the characteristics of low viscosity, high diffusivity and zero surface tension. It can easily penetrate into all parts of the waste fiber web, and can easily penetrate the tiny pores and cracks inside the fibers, as well as the pollutant interface. At the same time, supercritical carbon dioxide has excellent dissolving ability and has a strong ability to dissolve organic pollutants such as grease, mineral oil, and residual dyes, which can be carried away with the fluid, thereby "extracting" the pollutants hidden deep inside the fiber web. It has a strong cleaning ability. Subsequently, for the soaked fiber web obtained after cleaning, this design uses high-pressure carbon dioxide fluid (supercritical carbon dioxide or subcritical carbon dioxide) to form a high-speed fluid jet through a specific nozzle device to exert a strong mechanical impact on the soaked fiber web. This impact can cause the fibers to entangle with each other, thereby enhancing the mechanical strength of the nonwoven fabric. Secondly, cleaning facilitates entanglement. During cleaning, the fibers in the waste fiber web are cleaned by supercritical carbon dioxide and swelled and plasticized, which significantly reduces the difficulty of entanglement, resulting in higher entanglement efficiency and better effect. Cleaning means that supercritical carbon dioxide can penetrate into the fiber interior, dissolve and remove impurities such as oil. These impurities would originally adhere to the fibers like "glue," hindering their sliding and entanglement. However, after these impurities are removed, a clean physical interface is created for subsequent entanglement, making entanglement more efficient. Thirdly, entanglement facilitates cleaning; the high-pressure fluid jet impacts and agitates the soaked fiber web, much like a "powerful washing machine." The shearing force of the fluid jet mechanically peels away loosely attached contaminants after cleaning, enabling online fine cleaning and exposing a larger area to the fluid jet. The supercritical or subcritical carbon dioxide that constitutes the fluid jet also has strong dissolving power. In particular, supercritical carbon dioxide can utilize the large exposed area to dissolve contaminants on the fibers more extensively, thereby further enhancing the cleaning effect. Fourthly: Although the cleaning operation in the pretreatment tank and the entanglement operation in the entanglement chamber can achieve a cooperative effect, they are still two separate operations. This separation makes it easier to control the pretreatment tank and the entanglement chamber at different optimal pressures (e.g., medium pressure for pretreatment to ensure solubility, and high pressure for entanglement to ensure impact force), so that each can achieve better cleaning and entanglement effects, thereby achieving the best overall cleaning and entanglement effect. Therefore, this invention not only achieves the synergistic effect of cleaning and entanglement, which is beneficial to improving the recycling effect, but also has strong controllability and can optimize the two processes separately, thereby achieving a better recycling effect overall.

[0020] 2. The present invention discloses a method, product, and system for cleaning and recycling waste textiles using carbon dioxide fluid. The waste fiber web is first cleaned to obtain a soaked fiber web, and then the fiber web is soaked again using a fluid jet hydroentangling process to obtain a reinforced fiber web. The cleaning is performed using supercritical carbon dioxide, and the entanglement is achieved using supercritical or subcritical carbon dioxide. The advantages of this design include: Firstly, the entire process does not require the use of water or harmful chemical solvents, eliminating wastewater treatment problems at the source. It enables the green and high-value recycling and reuse of waste textiles, making it a green cleaning and entanglement technology. Secondly, the fluid jet uses supercritical or subcritical carbon dioxide, which, compared with the existing hydroentangling process, does not use water, thus saving a lot of water resources and greatly reducing water consumption. At the same time, precisely because the jet is free from dependence on water, the overall equipment can save high-energy-consuming water treatment devices (such as filtration, softening, and purification equipment), thereby greatly reducing energy consumption. Thirdly: After entanglement, supercritical or subcritical carbon dioxide will vaporize due to pressure reduction to generate gaseous carbon dioxide. Compared with existing spunlace, this process not only saves energy-intensive drying equipment, but also ensures that all substances constituting the fluid jet are residue-free on the nonwoven fabric, while existing spunlace will leave residue. It is more suitable for high-end nonwoven products, such as high-end hygiene products. Fourthly, the fluid jet is composed of carbon dioxide, which is free of impurities and ensures the stability of the fluid jet. Unlike existing hydroentanglement systems, it does not exhibit turbulence, which is beneficial for improving the entanglement effect. Therefore, this invention is not only green and environmentally friendly, with low water and energy consumption, but also enhances the entanglement effect and leaves no residue, making it more suitable for the production of high-end nonwoven fabrics.

[0021] 3. In the method, product, and system for cleaning and recycling waste textiles using carbon dioxide fluid of the present invention, a pretreatment tank is preferably connected to a circulation pipeline of supercritical carbon dioxide. This circulation pipeline is connected to a high-temperature, high-pressure filter. This design, during the static soaking stage, not only allows the "dirty" supercritical carbon dioxide carrying contaminants to circulate, but also allows it to pass through the high-temperature, high-pressure filter during circulation to trap the contaminants. This allows the purified "clean" supercritical carbon dioxide to be reused for static soaking, achieving continuous online cleaning. This ensures both high cleaning efficiency and improved utilization of supercritical carbon dioxide. Therefore, the present invention can achieve efficient online cleaning with supercritical carbon dioxide, resulting in excellent cleaning and supercritical carbon dioxide utilization.

[0022] 4. In the method, product, and system for cleaning and recycling waste textiles using carbon dioxide fluid of the present invention, the preferred static soaking time is 10-30 minutes. This design allows supercritical carbon dioxide sufficient time to penetrate and swell the fibers, dissolving most of the contaminants into the supercritical carbon dioxide matrix. This achieves a deep cleaning process dominated by "dissolution and extraction," ensuring cleaning effectiveness and laying the foundation for better subsequent entanglement reinforcement. Therefore, the present invention can achieve deep cleaning, which is beneficial for subsequent entanglement reinforcement. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] In the diagram: 1. Waste fiber web; 2. Soaked fiber web; 3. Reinforced fiber web; 4. Pretreatment tank; 5. Entanglement chamber; 6. Supercritical carbon dioxide fluid; 7. Fluid jet; 8. Nozzle. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] See Figure 1 A method for cleaning and recycling waste textiles using carbon dioxide fluid, the method comprising the following steps: Step 1, Preparation: Obtain waste fiber mesh; Step 2, Supercritical Cleaning Step: First, place the above-mentioned waste fiber web into the pretreatment tank, then inject supercritical carbon dioxide into the pretreatment tank until the waste fiber web is soaked in supercritical carbon dioxide. Then, control the temperature and pressure in the pretreatment tank so that the waste fiber web is continuously and statically soaked in supercritical carbon dioxide to obtain the soaked fiber web. The third step, entanglement reinforcement step: First, take the soaked fiber web out of the pretreatment tank and send it into the entanglement chamber. Then, use a fluid jet composed of supercritical or subcritical carbon dioxide to spray the soaked fiber web from top to bottom. The fluid jet penetrates or enters the fiber web to entangle the fibers in the fiber web and wash away the contaminants on the fibers until the fiber web is transported out of the entanglement chamber, thereby obtaining the reinforced fiber web.

[0027] In the third step, during the process of the fluid jet penetrating or entering the fiber web to entangle and flush, the temperature and pressure in the entanglement chamber are controlled to be any of the following: The first method: After the fluid jet has penetrated or entered the fiber web, the fluid jet is vaporized in the entanglement chamber to generate gaseous carbon dioxide. The second method: After the fluid jet has penetrated or entered the fiber web, the fluid jet does not vaporize in the entanglement chamber. It only vaporizes when the remaining fluid jet is transported out of the entanglement chamber along with the reinforced fiber web, thus generating gaseous carbon dioxide.

[0028] In the first method, the gaseous carbon dioxide is first collected from the entanglement chamber, then compressed and cooled to re-fluidize it to obtain a fluid jet, which is then injected onto the soaked fiber web for recycling. In the second method, the gaseous carbon dioxide is first collected from outside the entanglement workroom, then compressed and cooled to re-fluidize it into a fluid jet, which is then directed at the soaked fiber web for recycling.

[0029] In the second step, controlling the temperature and pressure in the pretreatment tank means that the temperature is 32-80℃ and the pressure is 7.5-30MPa.

[0030] In the second step, the static soaking time is 5-60 minutes.

[0031] In the second step, the pretreatment tank is connected to a supercritical carbon dioxide circulation pipeline, and an external high-temperature and high-pressure filter is connected to the circulation pipeline; the supercritical carbon dioxide fluid circulates between the pretreatment tank and the high-temperature and high-pressure filter.

[0032] In the third step, the process of taking the soaked fiber web out of the pretreatment tank and sending it into the entanglement chamber is either a pressurized transfer or a transfer after pressure balancing. The pressurized transfer refers to the transfer achieved by connecting the pretreatment tank and the entanglement chamber through a pipeline, during which the system pressure is maintained above 7.5 MPa. The transfer after pressure balancing refers to: reducing the pressure of the pretreatment tank to atmospheric pressure, and then taking out the fiber web and placing it into the entanglement chamber.

[0033] There is a fourth step after the third step, which is: Step 4, Recycling Step: Gaseous carbon dioxide generated in Step 2 and / or Step 3 is collected, compressed and condensed, re-fluidized, and recycled for Step 2 or Step 3.

[0034] In the third step, the fluid jet dynamically impacts the fibers within the entanglement chamber. During this process, a back pressure is maintained within the entanglement chamber. This back pressure is configured to control the phase state and behavior of the fluid jet. The back pressure is 5–25 MPa, and the temperature is 0–50°C, specifically any one or any combination of the following: First pressure condition: The fluid jet is kept in a liquid or supercritical state during the impact process, and phase change vaporization occurs only after the impact is completed; The second pressure condition is to cause the fluid jet to undergo partial or complete phase change and vaporization during the impact process.

[0035] A nonwoven fabric prepared by the above method, the nonwoven fabric being composed of recycled fibers, having no chemical residues inside, and having a three-dimensional entanglement structure formed between the fibers.

[0036] A system for implementing the above-described method of cleaning and recycling waste textiles with carbon dioxide fluid, the system comprising: Pretreatment tank, configured to hold waste fiber web and maintain a supercritical carbon dioxide environment; The entanglement chamber is located downstream of the pretreatment tank and is equipped with nozzles for injecting supercritical or subcritical carbon dioxide fluid jets. A transfer device is provided between the pretreatment tank and the entanglement chamber. The transfer device is configured to realize the pressurized or atmospheric pressure transfer of the soaked fiber web from the pretreatment tank to the entanglement chamber.

[0037] The following are supplementary descriptions of the present invention: The fluid jet in this invention is composed of supercritical or subcritical carbon dioxide. The density of such substances is only 70%-80% of that of water. If it is sprayed at the same speed, although the overall kinetic energy is weaker than that of water, the fluid jet still has the ability to penetrate the fiber web because in existing hydroentanglements, not all of the kinetic energy of water is used to penetrate the fiber web.

[0038] Example 1: See Figure 1 A method for cleaning and recycling waste textiles using carbon dioxide fluid, the method comprising the following steps: Step 1, Preparation: Obtain waste fiber mesh 1; Step 2, supercritical cleaning step: First, place the above-mentioned waste fiber web 1 into the pretreatment tank 4, and then inject supercritical carbon dioxide into the pretreatment tank 4 until the waste fiber web 1 is immersed in supercritical carbon dioxide. Then, control the temperature and pressure in the pretreatment tank 4 so that the waste fiber web 1 is continuously and statically immersed in supercritical carbon dioxide to obtain the soaked fiber web 2. The third step, the entanglement and reinforcement step: First, the soaked fiber web 2 is taken out from the pretreatment tank 4 and then sent into the entanglement chamber 5. Then, a fluid jet 7 composed of supercritical carbon dioxide or subcritical carbon dioxide is injected from top to bottom into the soaked fiber web 2. The fluid jet 7 penetrates or enters the fiber web to entangle the fibers in the fiber web and wash away the contaminants on the fibers until the fiber web is transported outside the entanglement chamber 5, thereby obtaining the reinforced fiber web 3.

[0039] Example 2: The basic content is the same as in Example 1, except that: A nonwoven fabric prepared by the above method, the nonwoven fabric being composed of recycled fibers, having no chemical residues inside, and having a three-dimensional entanglement structure formed between the fibers.

[0040] Example 3: The basic content is the same as in Example 1, except that: There is a fourth step after the third step, which is: Step 4, Recycling Step: Gaseous carbon dioxide generated in Step 2 and / or Step 3 is collected, compressed and condensed, re-fluidized, and recycled for Step 2 or Step 3.

[0041] In the third step, the fluid jet 7 dynamically impacts the fibers within the entanglement chamber 5. During this process, a back pressure is maintained within the entanglement chamber 5. This back pressure is configured to control the phase state and behavior of the fluid jet 7. The back pressure is 5–25 MPa, and the temperature is 0–50°C, specifically any one or any combination of the following: First pressure condition: The fluid jet 7 is kept in a liquid or supercritical state during the impact process until the impact is completed before phase change and vaporization occur; The second pressure condition is to cause the fluid jet 7 to undergo partial or complete phase change and vaporization during the impact process.

[0042] Example 4: The basic content is the same as in Example 1, except that: In the third step, during the process of the fluid jet 7 penetrating or entering the fiber web to perform entanglement and flushing, the temperature and pressure inside the entanglement chamber 5 are controlled to be any of the following: The first method: After the process of the fluid jet 7 penetrating or entering the fiber web is completed, the fluid jet 7 is vaporized in the entanglement chamber 5 to generate gaseous carbon dioxide. The second method: After the process of the fluid jet 7 penetrating or entering the fiber web is completed, the fluid jet 7 does not vaporize in the entanglement chamber 5. It only vaporizes when the remaining fluid jet 7 is transported out of the entanglement chamber 5 along with the reinforced fiber web 3, so as to generate gaseous carbon dioxide.

[0043] Example 5: The basic content is the same as in Example 1, except that: A system for implementing the above-described method of cleaning and recycling waste textiles with carbon dioxide fluid, the system comprising: Pretreatment tank 4 is configured to contain waste fiber web 1 and maintain a supercritical carbon dioxide environment; Entanglement chamber 5 is located downstream of the pretreatment tank 4 and is equipped with nozzles 8 for spraying supercritical or subcritical carbon dioxide fluid jets. A transfer device is provided between the pretreatment tank 4 and the entanglement chamber 5. The transfer device is configured to realize the pressurized or atmospheric pressure transfer of the soaked fiber web 2 from the pretreatment tank 4 to the entanglement chamber 5.

[0044] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for cleaning and recycling waste textiles using carbon dioxide fluid, characterized in that: The method includes the following steps: Step 1, Preparation: Obtain waste fiber mesh; Step 2, Supercritical Cleaning Step: First, place the above-mentioned waste fiber web into the pretreatment tank, then inject supercritical carbon dioxide into the pretreatment tank until the waste fiber web is soaked in supercritical carbon dioxide. Then, control the temperature and pressure in the pretreatment tank so that the waste fiber web is continuously and statically soaked in supercritical carbon dioxide to obtain the soaked fiber web. The third step, entanglement reinforcement step: First, take the soaked fiber web out of the pretreatment tank and send it into the entanglement chamber. Then, use a fluid jet composed of supercritical or subcritical carbon dioxide to spray the soaked fiber web from top to bottom. The fluid jet penetrates or enters the fiber web to entangle the fibers in the fiber web and wash away the contaminants on the fibers until the fiber web is transported out of the entanglement chamber, thereby obtaining the reinforced fiber web.

2. The method for cleaning and recycling waste textiles with carbon dioxide fluid according to claim 1, characterized in that: In the third step, during the process of the fluid jet penetrating or entering the fiber web to entangle and flush, the temperature and pressure in the entanglement chamber are controlled to be any of the following: The first method: After the fluid jet has penetrated or entered the fiber web, the fluid jet is vaporized in the entanglement chamber to generate gaseous carbon dioxide. The second method: After the fluid jet has penetrated or entered the fiber web, the fluid jet does not vaporize in the entanglement chamber. It only vaporizes when the remaining fluid jet is transported out of the entanglement chamber along with the reinforced fiber web, thus generating gaseous carbon dioxide.

3. The method for cleaning and recycling waste textiles with carbon dioxide fluid according to claim 2, characterized in that: In the first method, the gaseous carbon dioxide is first collected from the entanglement chamber, then compressed and cooled to re-fluidize it to obtain a fluid jet, which is then injected onto the soaked fiber web for recycling. In the second method, the gaseous carbon dioxide is first collected from outside the entanglement workroom, then compressed and cooled to re-fluidize it into a fluid jet, which is then directed at the soaked fiber web for recycling.

4. A method for cleaning and recycling waste textiles using carbon dioxide fluid according to claim 1, 2, or 3, characterized in that: In the second step, controlling the temperature and pressure in the pretreatment tank means that the temperature is 32-80℃ and the pressure is 7.5-30MPa.

5. A method for cleaning and recycling waste textiles using carbon dioxide fluid according to claim 1, 2, or 3, characterized in that: In the second step, the static soaking time is 5-60 minutes.

6. A method for cleaning and recycling waste textiles using carbon dioxide fluid according to claim 1, 2, or 3, characterized in that: In the third step, the process of taking the soaked fiber web out of the pretreatment tank and sending it into the entanglement chamber is either a pressurized transfer or a transfer after pressure balancing. The pressurized transfer refers to the transfer achieved by connecting the pretreatment tank and the entanglement chamber through a pipeline, during which the system pressure is maintained above 7.5 MPa. The transfer after pressure balancing refers to: reducing the pressure of the pretreatment tank to atmospheric pressure, and then taking out the fiber web and placing it into the entanglement chamber.

7. A method for cleaning and recycling waste textiles using carbon dioxide fluid according to claim 1, 2, or 3, characterized in that: There is a fourth step after the third step, which is: Step 4, Recycling Step: Gaseous carbon dioxide generated in Step 2 and / or Step 3 is collected, compressed and condensed, re-fluidized, and recycled for Step 2 or Step 3.

8. A method for cleaning and recycling waste textiles using carbon dioxide fluid according to claim 1, 2, or 3, characterized in that: In the third step, the fluid jet dynamically impacts the fibers within the entanglement chamber. During this process, a back pressure is maintained within the entanglement chamber. This back pressure is configured to control the phase state and behavior of the fluid jet. The back pressure is 5–25 MPa, and the temperature is 0–50°C, specifically any one or any combination of the following: First pressure condition: The fluid jet is kept in a liquid or supercritical state during the impact process, and phase change vaporization occurs only after the impact is completed; The second pressure condition is to cause the fluid jet to undergo partial or complete phase change and vaporization during the impact process.

9. A nonwoven fabric prepared by the method for recycling waste textiles using carbon dioxide fluid cleaning as described in claim 1, 2, or 3, characterized in that: The nonwoven fabric is made of recycled fibers, has no chemical residues inside, and forms a three-dimensional entanglement structure between the fibers.

10. A system for implementing the method of washing and recycling waste textiles with carbon dioxide fluid as described in claim 1, 2, or 3, characterized in that: The system includes: Pretreatment tank, configured to hold waste fiber web and maintain a supercritical carbon dioxide environment; The entanglement chamber is located downstream of the pretreatment tank and is equipped with nozzles for injecting supercritical or subcritical carbon dioxide fluid jets. A transfer device is provided between the pretreatment tank and the entanglement chamber. The transfer device is configured to realize the pressurized or atmospheric pressure transfer of the soaked fiber web from the pretreatment tank to the entanglement chamber.

Images