Process for preparing modified non-woven fabric produced by recycling pp food container crushed pieces

Abstract

A process for preparing a modified non-woven fabric produced by recycling PP food container crushed pieces, belonging to the technical field of non-woven fabrics. The process comprises the following steps: first, sorting, cleaning and screening recycled PP food container crushed pieces, and then mixing same with a modification enhancer for later use; next, using a screw feeder to convey the prepared raw materials to a screw extruder for melt extrusion; then extruding a melt by means of a spinneret, performing spinning forming, cooling and solidifying a fiber by means of a cooling device, and forming a continuous fiber mesh after laying; and finally reinforcing the fiber mesh by means of drawing and thermal bonding, forming a non-woven fabric having required physical properties after laying, and performing heat treatment and calendering treatment. Said preparation process effectively uses waste PP food containers, reduces the use of virgin PP, and reduces production costs, while also reducing environmental pollution, and having significant economic and social benefits.

Description

A process for producing modified nonwoven fabric using recycled PP lunch box fragments Technical Field

[0001] This invention belongs to the field of nonwoven fabric technology, specifically, it relates to a process for preparing modified nonwoven fabric using recycled PP lunch box fragments. Background Technology

[0002] Polypropylene (PP) is one of the five major general-purpose plastics. It has excellent physical and chemical properties, such as high strength and rigidity, good heat resistance and electrical insulation, excellent chemical resistance and vapor permeability resistance. PP materials are widely used in automobiles, home appliances, food packaging, medical and health fields due to their low density, light weight, high design flexibility, and many advantages such as being green and environmentally friendly, having excellent performance and low manufacturing cost.

[0003] PP nonwoven fabric is a nonwoven sheet material made from PP as the main raw material through processes such as meltblowing and spinning. Compared with woven fabrics, PP nonwoven fabric has advantages such as light weight, high strength, good air permeability, and low cost, and has broad application prospects in medical, hygiene, and filtration fields. Traditional PP nonwoven fabrics mostly use virgin PP chips or powder as raw materials, which puts high requirements on the purity and melt index of PP raw materials. Recycling and reusing waste PP lunch boxes to produce PP nonwoven fabric can not only reduce the amount of virgin PP used and lower production costs, but also reduce the environmental impact, resulting in significant economic and social benefits.

[0004] However, directly using recycled PP lunch boxes in nonwoven fabric production still faces many technical challenges: Recycled PP lunch boxes have low purity, containing other plastics such as PE, as well as impurities like paper scraps and metals, affecting spinning stability; Recycled PP lunch boxes have a high and fluctuating melt index, which is detrimental to spinning process control; The irregular shape and low bulk density of broken recycled PP lunch boxes can cause difficulties in transportation and metering; Recycled PP lunch boxes easily retain residual odors, requiring further deodorization treatment to meet the application requirements of sanitary materials and other fields.

[0005] Therefore, there is an urgent need to develop systematic recycling processes, including efficient cleaning and sorting, modification and volume enhancement, melt homogenization, and equipment optimization for recycled PP food containers. These processes aim to overcome the technical bottlenecks in the production of nonwoven fabrics from recycled PP food container fragments, enabling their high-value and large-scale utilization and promoting the development of a circular economy in the plastics industry. This is of great significance for reducing the consumption of primary resources, alleviating environmental pollution pressure, and promoting the green and sustainable development of the industry. Summary of the Invention

[0006] 1. Problems to be solved: This invention aims to address several shortcomings in the existing technology of producing nonwoven fabric using recycled PP lunch box fragments. The main problems include: Low raw material purity: Recycled PP lunch boxes usually contain other plastics, paper scraps, metals and other impurities, which will affect the stability of spinning and product quality.

[0007] Unstable melt flow index: The melt flow index of recycled PP lunch boxes is high and fluctuates greatly, making it difficult to control the spinning process.

[0008] Irregular material shape: The irregular shape and low bulk density of the broken pieces make it difficult to transport and measure.

[0009] Odor Residue: Recycled PP food containers may retain an odor, requiring further processing to meet application requirements.

[0010] This invention aims to improve the utilization efficiency of recycled PP lunch boxes by developing a modified nonwoven fabric preparation process. The process includes efficient cleaning and sorting, modification and strengthening treatment, melt homogenization and equipment optimization, etc., to ensure the purity and performance of the recycled materials and meet the requirements of nonwoven fabric production. This not only reduces the use of virgin PP and lowers production costs, but also effectively reduces environmental pollution, realizes the recycling of plastic resources, and promotes green and sustainable development.

[0011] 2. Technical Solution To solve the above problems, the technical solution provided by this invention is as follows: A modified nonwoven fabric preparation process using recycled PP lunch box fragments, including the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with a modifier for later use; Figure 1 shows the conventional spunbond nonwoven fabric production process. Direct spinning of recycled PP lunch box fragments is a new type of high-value utilization technology for recycled polypropylene materials. Its production process is simplified and is different from traditional weaving, flat yarn and other drawing processes. The specific differences are as follows: Different process principles Direct spinning: The recycled PP fragments are melted by a screw and then directly extruded through a spinneret. After cooling and stretching, fine filaments are formed and then nonwoven fabric is obtained by web forming. It is a typical melt spinning process.

[0012] Filament drawing: Extruding PP melt into films or coarse filaments, which are then stretched and deformed into fine filaments. In weaving and flat yarn processes, filament drawing is a separate process following extrusion molding.

[0013] Direct spinning with different equipment configurations: The main equipment includes screw extruders, spinnerets, cooling and stretching devices, web laying devices, etc. The process flow is short and the equipment is relatively simple.

[0014] Fiber drawing: In addition to extruders, specialized stretching equipment such as drawing machines and winding machines is required. The process is long and the equipment is complex.

[0015] Different product forms: Direct spinning: The product is a fiber web arranged in an oriented or random manner, which can be directly used in non-woven fabrics.

[0016] Filament drawing: The product is a continuous filament, which needs to be made into fabric or non-woven fabric through processes such as weaving or needle punching.

[0017] Direct spinning with different fiber fineness: The fiber fineness is 1-3 dtex, which belongs to medium fine denier.

[0018] Filament drawing: The fiber fineness is generally >3dtex, and it is mostly coarse denier filament.

[0019] Production efficiency differs between direct spinning and direct spinning: the production process is shorter, the spinning speed is as high as 3000m / min or more, and the production efficiency is high.

[0020] Wire drawing: involves many processes, complex equipment, and relatively low production efficiency.

[0021] The products have different performance characteristics: Direct spinning has a more uniform fiber fineness distribution, the non-woven fabric has a softer feel, and the strength is slightly lower.

[0022] Filament: The filaments have high strength and excellent mechanical properties, but poor softness.

[0023] Therefore, using recycled PP lunch box fragments to directly produce spunbond nonwoven fabric can simplify the process, reduce production costs, and improve production efficiency, while giving recycled PP new high-value-added uses; this is of great significance for promoting plastic recycling and developing a circular economy; however, the direct spinning process also puts forward higher requirements for raw material purity and melt uniformity, so optimizing the raw material formula and process control is the key to the industrial application of this technology (2) Feeding and conveying: a screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; In our use, it is recommended to use Zhangjiagang Lingang Machinery Co., Ltd., model 51 / 80 feeder, motor 2.2 (KW).

[0024] In summary, the following optimization solutions are proposed: Replace the single-screw extruder with a twin-screw extruder: Twin-screw extruders have stronger propulsion and mixing / dispersing capabilities, effectively overcoming feeding difficulties caused by the low bulk density and irregular shape of the crushed material. The staggered meshing design of the twin screws helps the crushed material agglomerate, improves melt uniformity, and reduces bubble formation. Use side feeding or multi-point feeding to prevent material from falling directly into the screw space and introducing air. Install a filling device at the feed port to ensure compact feeding and reduce air ingress.

[0025] The above optimization measures can effectively solve problems such as low bulk density, difficulty in feeding, and melt bubbles in the application of recycled PP food container fragments in spunbond nonwoven fabric production lines, thereby improving output and product quality and achieving high-value utilization of resources. In specific implementation, further optimization and adaptive adjustments are needed based on equipment conditions and material characteristics.

[0026] For feeding and conveying, the following suggestions and measures are recommended: Use a screw conveyor: Due to the low bulk density and irregular shape of recycled PP food container fragments, traditional vacuum negative pressure suction systems are prone to "bridging" and causing feeding blockage. A screw conveyor can be used instead, as its screw design can better handle low-density and irregularly shaped materials, reducing the occurrence of "bridging".

[0027] Pneumatic conveying system: Consider using a dilute phase pneumatic conveying system, which is suitable for handling materials with low density and can effectively convey irregularly shaped fragments by adjusting the airflow speed and pressure.

[0028] Material Pretreatment: An additional pretreatment step is added: before conveying, the recycled PP food container fragments are pretreated, such as by further crushing or granulation, to increase bulk density and uniformity. This reduces the risk of blockage during conveying.

[0029] Piping Design: Optimize piping design: Design wider piping or increase the bending radius to reduce material blockage within the piping. Ensure smooth inner walls of the piping to reduce frictional resistance.

[0030] Install vibration devices: Install vibration devices at critical locations in the conveying pipeline to help prevent material buildup and blockage.

[0031] Real-time monitoring and adjustment: Real-time monitoring system: Install sensors and monitoring systems to detect changes in flow and pressure during the conveying process in real time, and adjust conveying parameters in a timely manner to avoid blockage.

[0032] Automated control: Automated systems are used to adjust conveying speed and airflow based on real-time monitoring data to optimize conveying efficiency.

[0033] Mixing and Homogenization: Homogenization treatment: Before conveying, the fragments from different sources are mixed to ensure the uniformity and consistency of the material, thereby reducing flow instability problems during the conveying process.

[0034] The above optimization measures can effectively improve the conveying efficiency of recycled PP lunch box fragments in spunbond nonwoven fabric production, reduce blockages and downtime, and thus improve overall production efficiency and product quality.

[0035] (3) Screw extrusion: A screw extruder is used to melt and extrude the raw material from step (2); The above process steps can effectively solve the problems of insufficient feeding and melt bubbles in the application of recycled PP lunch box fragments in spunbond nonwoven fabric production lines, improve output and product quality, and realize the high-value utilization of resources. In specific implementation, it is also necessary to optimize the combination and adapt to the equipment conditions and material characteristics.

[0036] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a nonwoven fabric; (5) Cooling and solidification: The fibers spun in step (4) are cooled and solidified by a cooling device, and a continuous fiber web is formed after web laying; (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched, and then nonwoven fabric with the required physical properties is formed by thermal bonding and web laying; (7) Post-treatment: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering.

[0037] Preferably, the sorting steps in step (1) are as follows: pour the PP lunch box fragments into clean water, stir, and then separate the floating PP lunch box fragments; the washing steps in step (1) are as follows: put the sorted PP lunch box fragments into hot water at 60℃-80℃ and stir to wash; the screening steps in step (1) are as follows: use a crusher to control the size of the washed PP lunch box fragments to within 10mm.

[0038] Several key aspects need to be considered: Raw material purity and composition control: Purity requirements: Ensure that the non-PP component in the recycled PP food container fragments is less than 3%. This helps improve the stability of the spinning process and reduces the impact of impurities on equipment wear and product quality.

[0039] Uniformity of composition: By mixing different batches of recycled materials, the influence of the melt index fluctuation of a single recycled material is reduced, thereby stabilizing the overall melt index of the recycled material and facilitating spinning.

[0040] Melt Flow Index (MFI) Control: Target Range: Use PP raw materials with a melt flow index of 25-40 g / 10 min to ensure good melt flowability and spinning performance.

[0041] Melt index adjustment: The melt index is adjusted by adding modifiers or mixing PP materials with different melt indices to make it suitable for the production requirements of spunbond nonwoven fabrics.

[0042] Impurity handling: Impurity removal: The recycled PP lunch boxes are strictly sorted and cleaned to remove impurities such as film, paper scraps, and metal, and to prevent the filter screen and spinneret from clogging.

[0043] Filtration system: A multi-stage filtration system is used during melt extrusion to further remove residual minute impurities.

[0044] Molecular weight distribution: Uniformity control: Select PP raw materials with narrow molecular weight distribution to improve spinning stability and product mechanical properties.

[0045] Modification treatment: By adding compatibilizers and toughening agents to PP, the molecular weight distribution is improved, enhancing the toughness and impact resistance of the material.

[0046] Process optimization: Temperature control: During screw extrusion and spinning, the temperature of each zone is precisely controlled to ensure that the PP is fully melted and uniformly mixed.

[0047] Equipment adjustment: Adjust the screw design and extrusion equipment according to the characteristics of the raw materials to meet the processing requirements of recycled PP.

[0048] The above measures can effectively solve the raw material problem of recycled PP lunch box fragments in the production of spunbond nonwoven fabrics, improve product quality, reduce production costs, and promote the recycling of plastics.

[0049] The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: In step (1), the added mass of the modifier is 10%-15% of the PP lunch box fragments; The components of the modifier in step (1), by weight, include the following: 25-40 parts of glycine, 10-20 parts of nanocomposite material, 5-10 parts of azobisisobutyronitrile, and 15-25 parts of polyethylene glycol; The mixing pressure in step (1) is 2MPa-4MPa, and the mixing temperature is 65℃-75℃.

[0050] The modified nonwoven fabric preparation process using recycled PP lunch box fragments is described below. The preparation method of the nanocomposite material is as follows: Magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate are ground and mixed in a mass ratio of (1-5):(1-5):(3-6):(2-8):(1-6). Imidazole-4-carboxylic acid (50-80 times the mass of the mixture) is added, and the mixture is stirred at 80℃-90℃ for 8-16 hours. The precipitate is repeatedly washed with anhydrous ethanol, followed by vacuum freeze-drying at -80℃ for 24 hours. The resulting powder is transferred to a high-temperature calcining furnace and calcined at 400℃-600℃ under nitrogen atmosphere for 9-13 hours, with a heating rate of 10℃ / min. In this part, the amount of the modifier is 10%-15% of the PP lunch box fragments, indicating that although the amount is small, its effect is significant. The modifying and reinforcing agent contains: Glycine (25-40 parts): Its amino groups can chemically react with polar groups such as maleic anhydride introduced onto PP, forming grafted modified PP after web formation, thus improving the polarity and compatibility of PP. Nanocomposite materials (10-20 parts): Nanoparticles have a large specific surface area and high surface energy, which can form strong interfacial forces with PP, achieving a compatibilizing and reinforcing effect. Azobisisobutyronitrile (5-10 parts): A commonly used free radical initiator. Polyethylene glycol (15-25 parts): A hydrophilic polymer that can improve the hydrophilicity and antistatic properties of PP. The mixing and modification process is carried out under high pressure of 2-4 MPa and temperature of 65-75℃, which is conducive to promoting the melt blending and chemical reaction between PP and the modifying components. The preparation process of nanocomposite materials is complex, involving multiple steps such as mixing and grinding, solvothermal reaction, freeze drying, and high-temperature calcination. Its structure and properties are finely controlled, making it a high-performance functional filler. In summary, this modified reinforcing agent, through physical blending and chemical grafting reactions, can significantly improve the polarity, compatibility, mechanical properties, and functionality of recycled PP food container fragments, enabling them to meet the production requirements of spunbond nonwoven fabrics. Therefore, the rational use of the modified reinforcing agent is one of the core elements of this invention.

[0051] Meanwhile, antibacterial effects can be achieved with nanocomposite materials (high-entropy nanozymes). Specifically, high-entropy nanozymes are a novel type of multi-component nanocomposite material, composed of five or more metal elements in near-equal atomic proportions. This multi-component composite strategy breaks through the component limitations of traditional nanozymes, providing greater flexibility for the performance regulation of nanozymes.

[0052] High-entropy nanozymes combine the characteristics of high-entropy alloys and nanozymes. On the one hand, the high-entropy effect gives nanoparticles a more uniform elemental distribution, a more stable structure, and a smaller size; on the other hand, the nanozyme effect endows the material with excellent biocatalytic properties, such as peroxidase and oxidase activities.

[0053] In the field of antibacterial research, high-entropy nanozymes primarily function through peroxidase-like activity. They can catalyze the production of highly reactive hydroxyl radicals (·OH) from hydrogen peroxide (H2O2), thereby causing oxidative damage to bacteria, destroying bacterial cell membranes, proteins, and DNA, and ultimately leading to bacterial death.

[0054] Compared to traditional single- or binary component nanozymes, high-entropy nanozymes exhibit higher peroxidase activity and a broader spectrum of antibacterial effects. This is attributed to the synergistic catalytic effect brought about by the high-entropy effect and the exposure of more active sites.

[0055] Furthermore, the enzymatic properties and antibacterial effects of high-entropy nanozymes can be further optimized by adjusting their composition, ratio, morphology, and size. For example, doping with elements that have photothermal effects can achieve photothermal-enzymatic synergistic antibacterial activity; introducing ligands with specific binding capabilities can improve the selectivity and targeting of antibacterial activity.

[0056] Currently, although high-entropy nanozymes have shown promising application prospects in the field of antibacterial research, there are still some problems to be solved, such as the biosafety assessment of materials, in-depth research on antibacterial mechanisms, optimization of preparation processes, and exploration of large-scale applications.

[0057] In summary, as a novel nanocomposite material, high-entropy nanozymes have brought new research ideas and applications to the field of antibacterial research. By leveraging the synergistic effects of multiple components and the catalytic advantages of nanozyme catalysis, high-entropy nanozymes are expected to become a class of highly efficient, broad-spectrum, and long-lasting antibacterial agents with broad application prospects in medical devices, wound dressings, and antifouling coatings. In the future, high-entropy nanozymes are expected to be combined with other antibacterial technologies to develop more intelligent and precise antibacterial strategies.

[0058] The modified nonwoven fabric preparation process using recycled PP lunch box fragments, the spiral feeder in step (2) is a spiral conveyor with a pitch of 0.5 to 0.6 times the spiral diameter.

[0059] The modified nonwoven fabric preparation process using recycled PP lunch box fragments has the following parameters for melt extrusion in step (3): Zone 1: 215-225℃, Zone 2: 220-230℃, Zone 3: 225-235℃, Zone 4: 230-240℃, Zone 5: 235-245℃, Zone 6: 230-240℃.

[0060] The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: in step (4), the spinneret aperture is 0.2-0.4 mm; in step (4), the spinneret temperature is 280-300℃; in step (4), the spinning speed is 1500-3500 m / min; and in step (4), the fiber fineness range is 1.0-2.5 dtex.

[0061] The modified nonwoven fabric preparation process using recycled PP lunch box fragments has the following steps: in step (5), the cooling and curing temperature drop is 5℃ / min; in step (5), the final temperature after cooling and curing is 25℃; and in step (5), the ambient humidity for cooling and curing is 60%.

[0062] The modified nonwoven fabric preparation process using recycled PP lunch box fragments has the following parameters in step (6): the stretching ratio is 1.2-3.5 times, the stretching temperature is 40-60℃, and the stretching speed is 80-150m / min; the thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 140-160℃, the roll pressure is 40-80N / mm, and the roll gap is 0.1-1.0mm.

[0063] The modified nonwoven fabric preparation process using recycled PP lunch box fragments has the following parameters in step (7): temperature is 130-160℃, heat treatment time is 30-120s; the parameters in step (7) for calendering are as follows: calendering temperature is 100-140℃, calendering pressure is 20-100N / mm, calendering time is 2-10s, and calendering roller linear speed is 10-100m / min.

[0064] 3. Beneficial effects: Resource recycling: By using recycled PP lunch box fragments as raw materials, the demand for virgin polypropylene is reduced, production costs are lowered, and the environmental impact of plastic waste is effectively reduced.

[0065] Product performance enhancement: The addition of modifiers significantly improves the mechanical properties of nonwoven fabrics, including tensile strength, tear strength, and elongation at break. These modifiers enhance the bonding force between fibers by improving the polarity and compatibility of the material, thereby improving the overall performance of the product.

[0066] Process optimization: This preparation process, through steps such as sorting, cleaning, and screening, ensures the purity and uniformity of the recycled materials, optimizes the melt extrusion and spinning process, and improves production efficiency and product quality.

[0067] Antibacterial properties: The use of nanocomposite materials endows nonwoven fabrics with antibacterial properties, effectively inhibiting bacterial growth and enhancing the application value of the product in fields such as medical and health care.

[0068] Environmental friendliness: The entire process reduces waste generation and disposal difficulties, meets the requirements of green manufacturing and sustainable development, and helps reduce the environmental burden of plastics.

[0069] In summary, this invention not only achieves high-value utilization of waste PP lunch boxes, but also improves the performance and application range of non-woven fabrics through technological innovation, resulting in significant economic and social benefits. Attached Figure Description

[0070] Figure 1 is a flow chart of the conventional spunbond nonwoven fabric production process; Figure 2 is a structural principle diagram of the nanocomposite material in this invention; Figure 3 is a high-resolution transmission electron microscope (HRTEM) image of the nanocomposite material prepared by scheme 3 in this invention; Figure 4 is an electron paramagnetic resonance (EPR) spectrum of the nanocomposite material prepared by scheme 3 in this invention; Figure 5 is a graph showing the antibacterial survival rate of the nonwoven fabrics prepared by schemes 1-5 in this invention. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0072] It should be noted that in this invention, all weight parts or proportions are in the international standard unit kilogram (Kg).

[0073] Meanwhile, the recycled PP food container fragments came from disposable takeout food containers manufactured by Sichuan Hongchang Plastic Industry Co., Ltd., with item number HC092327, brand name: Maryya, and material: polypropylene (PP).

[0074] Scheme 1 The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with a modifier for later use; Specifically: the sorting steps in step (1) are as follows: the PP lunch box fragments are poured into clean water, stirred and the floating PP lunch box fragments are separated; the cleaning steps in step (1) are as follows: the sorted PP lunch box fragments are placed in 60℃ hot water and stirred and cleaned; the screening steps in step (1) are as follows: the size of the cleaned PP lunch box fragments is controlled within 10mm by a crusher.

[0075] The modified reinforcing agent added in step (1) is 10% of the mass of the PP lunch box fragments; the components of the modified reinforcing agent in step (1), by weight, include the following: The mixing pressure in step (1) is 2 MPa and the mixing temperature is 75°C.

[0076] The preparation method of the nanocomposite material is as follows: Magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate are ground and mixed in a mass ratio of 1:5:3:8:1. Imidazole-4-carboxylic acid is added at 50 times the mass of the mixture. The mixture is stirred and reacted at 80°C for 16 hours. The precipitate is repeatedly washed with anhydrous ethanol. Then, it is freeze-dried under vacuum at -80°C for 24 hours. The resulting powder is transferred to a high-temperature calcining furnace and calcined at 400°C for 13 hours under nitrogen atmosphere, with a heating rate of 10°C / min.

[0077] (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; specifically, the screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.5 times the screw diameter.

[0078] (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; The parameters of melt extrusion in step (3) are as follows: Zone 1: 215℃, Zone 2: 230℃, Zone 3: 225℃, Zone 4: 240℃, Zone 5: 235℃, Zone 6: 240℃.

[0079] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a filament; Specifically, the orifice diameter of the spinneret in step (4) is 0.2 mm; the temperature of the spinneret in step (4) is 300 °C; the spinning speed of the spinneret in step (4) is 1500 m / min; and the fineness range of the filament formed in step (4) is 2.5 dtex.

[0080] (5) Cooling and curing: The fibers spun in step (4) are cooled and cured by a cooling device, and a continuous fiber web is formed after web laying; Specifically, the cooling and curing temperature drop in step (5) is 5℃ / min; the termination temperature after cooling and curing in step (5) is 25℃; and the ambient humidity during cooling and curing in step (5) is 60%.

[0081] (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; Specifically, the stretching parameters in step (6) are as follows: the stretching ratio is 1.2 times, the stretching temperature is 60℃, and the stretching speed is 80m / min; The thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 140℃, the roll pressure is 80N / mm, and the roll gap is 0.1mm.

[0082] (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. Specifically, the parameters of heat treatment in step (7) are as follows: temperature is 130℃, heat treatment time is 120s; The parameters of calendering in step (7) are as follows: calendering temperature is 100℃, calendering pressure is 100N / mm, calendering time is 2s, and calendering roller linear speed is 100m / min.

[0083] Scheme 2: The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with a modifier for later use; Specifically: The sorting steps in step (1) are as follows: Pour the PP lunch box fragments into clean water, stir and separate the floating PP lunch box fragments; The cleaning steps in step (1) are as follows: Put the sorted PP lunch box fragments into 80℃ hot water and stir and clean; The screening steps in step (1) are as follows: Use a crusher to control the size of the cleaned PP lunch box fragments to within 10mm.

[0084] The modified reinforcing agent added in step (1) is 15% of the mass of the PP lunch box fragments; the components of the modified reinforcing agent in step (1), by weight, include the following: The mixing pressure in step (1) is 4 MPa and the mixing temperature is 65℃.

[0085] The preparation method of the nanocomposite material is as follows: Magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate are ground and mixed in a mass ratio of 5:1:6:2:6. Imidazole-4-carboxylic acid, which is 80 times the mass of the mixture, is added and stirred at 90°C for 8 hours. The precipitate is repeatedly washed with anhydrous ethanol and then freeze-dried under vacuum at -80°C for 24 hours. The resulting powder is transferred to a high-temperature calcining furnace and calcined at 600°C for 9 hours under nitrogen atmosphere, with a heating rate of 10°C / min.

[0086] (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; specifically, the screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.6 times the screw diameter.

[0087] (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; The parameters of melt extrusion in step (3) are as follows: Zone 1: 225℃, Zone 2: 220℃, Zone 3: 235℃, Zone 4: 230℃, Zone 5: 245℃, Zone 6: 230℃.

[0088] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a filament; Specifically, the orifice diameter of the spinneret in step (4) is 0.4 mm; the temperature of the spinneret in step (4) is 280 °C; the spinning speed of the spinneret in step (4) is 3500 m / min; and the fineness range of the spun fiber in step (4) is 1.0 dtex.

[0089] (5) Cooling and curing: The fibers spun in step (4) are cooled and cured by a cooling device, and a continuous fiber web is formed after web laying; Specifically, the cooling and curing temperature drop in step (5) is 5℃ / min; the termination temperature after cooling and curing in step (5) is 25℃; and the ambient humidity during cooling and curing in step (5) is 60%.

[0090] (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; Specifically, the stretching parameters in step (6) are as follows: the stretching ratio is 3.5 times, the stretching temperature is 40℃, and the stretching speed is 150m / min; The thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 160℃, the roll pressure is 40N / mm, and the roll gap is 1.0mm.

[0091] (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. Specifically, the parameters of heat treatment in step (7) are as follows: temperature is 160℃, heat treatment time is 30s; The parameters of calendering in step (7) are as follows: calendering temperature is 140℃, calendering pressure is 20N / mm, calendering time is 10s, and calendering roller linear speed is 10m / min.

[0092] Scheme 3: The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with a modifier for later use; Specifically: The sorting steps in step (1) are as follows: Pour the PP lunch box fragments into clean water, stir and separate the floating PP lunch box fragments; The cleaning steps in step (1) are as follows: Put the sorted PP lunch box fragments into 70℃ hot water and stir and clean; The screening steps in step (1) are as follows: Use a crusher to control the size of the cleaned PP lunch box fragments to within 10mm.

[0093] The modified reinforcing agent added in step (1) is 13% of the mass of the PP lunch box fragments; the components of the modified reinforcing agent in step (1), by weight, include the following: The mixing pressure in step (1) is 3 MPa and the mixing temperature is 70°C.

[0094] The preparation method of the nanocomposite material is as follows: Magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate are ground and mixed in a mass ratio of 3:3:5:5:3. Imidazole-4-carboxylic acid is added in 65 times the mass of the mixture. The mixture is stirred and reacted at 85°C for 12 hours. The precipitate is repeatedly washed with anhydrous ethanol. Then, it is freeze-dried under vacuum at -80°C for 24 hours. The resulting powder is transferred to a high-temperature calcining furnace and calcined at 500°C for 11 hours under nitrogen atmosphere, with a heating rate of 10°C / min.

[0095] Figure 2 shows the structural diagram of the nanocomposite material, exhibiting a uniform structure, indicating the complete homogeneity of the five metal elements, thus achieving a catalytic effect. Figure 3 shows that the nanocomposite material exhibits a crystalline structure in all three regions, with an average lattice spacing of 0.220 nm. Figure 4 demonstrates that the intensity ratio of the four EPR signal peaks in the prepared nanocomposite material is 1:2:2:1, proving that ·OH is the main free radical generated during the catalytic process. DMPO (5,5-dimethyl-1-pyrroline N-oxide) is a commonly used spin trapping agent for capturing short-lived free radicals. ·OH (hydroxyl radical) is a highly reactive oxidizing free radical that widely participates in oxidation reactions. In the EPR (electron paramagnetic resonance) experiment, DMPO reacts with hydroxyl radicals (·OH) to form a stable radical adduct (DMPO-OH), allowing the presence and concentration of hydroxyl radicals to be detected by EPR spectroscopy. This method is commonly used to study oxidative stress, free radical reaction mechanisms, and the role of antioxidants. •OH is an extremely strong oxidizing agent with very high reactivity. It can react with a variety of biomolecules in bacteria, including proteins, nucleic acids, and lipids. Its bactericidal effects include: •OH can induce lipid peroxidation, damaging bacterial cell membrane structure; •OH can attack DNA molecules, causing DNA strand breaks and base damage; •OH can oxidize amino acid residues in proteins, leading to protein denaturation and inactivation; and •OH can interfere with normal bacterial metabolic processes by disrupting key enzymes and metabolites.

[0096] (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; specifically, the screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.5 times the screw diameter.

[0097] (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; The parameters of melt extrusion in step (3) are as follows: Zone 1: 215℃, Zone 2: 220℃, Zone 3: 225℃, Zone 4: 230℃, Zone 5: 235℃, Zone 6: 230℃.

[0098] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a filament; Specifically, the orifice diameter of the spinneret in step (4) is 0.3 mm; the temperature of the spinneret in step (4) is 290 °C; the spinning speed of the spinneret in step (4) is 2500 m / min; and the fineness range of the filament formed in step (4) is 2 dtex.

[0099] (5) Cooling and curing: The fibers spun in step (4) are cooled and cured by a cooling device, and a continuous fiber web is formed after web laying; Specifically, the cooling and curing temperature drop in step (5) is 5℃ / min; the termination temperature after cooling and curing in step (5) is 25℃; and the ambient humidity during cooling and curing in step (5) is 60%.

[0100] (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; Specifically, the stretching parameters in step (6) are as follows: the stretching ratio is 2 times, the stretching temperature is 50℃, and the stretching speed is 120 m / min; The thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 150℃, the roll pressure is 60N / mm, and the roll gap is 0.5mm.

[0101] (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. Specifically, the parameters of heat treatment in step (7) are as follows: temperature is 150℃, heat treatment time is 100s; The parameters of calendering in step (7) are as follows: calendering temperature is 120℃, calendering pressure is 60N / mm, calendering time is 5s, and calendering roller linear speed is 60m / min.

[0102] Scheme 4: The modified nonwoven fabric preparation process using recycled PP lunch box fragments includes the following steps: (1) Raw material preparation: sorting, cleaning and screening the recycled PP lunch box fragments; Specifically: the sorting steps in step (1) are as follows: pour the PP lunch box fragments into clean water, stir and separate the floating PP lunch box fragments; the cleaning steps in step (1) are as follows: put the sorted PP lunch box fragments into 60℃ hot water and stir and clean; the screening steps in step (1) are as follows: control the size of the cleaned PP lunch box fragments to within 10mm using a crusher.

[0103] (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; specifically, the screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.5 times the screw diameter.

[0104] (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; The parameters of melt extrusion in step (3) are as follows: Zone 1: 225℃, Zone 2: 230℃, Zone 3: 235℃, Zone 4: 240℃, Zone 5: 245℃, Zone 6: 240℃.

[0105] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a filament; Specifically, the orifice diameter of the spinneret in step (4) is 0.2 mm; the temperature of the spinneret in step (4) is 300 °C; the spinning speed of the spinneret in step (4) is 1500 m / min; and the fineness range of the filament formed in step (4) is 1.0 dtex.

[0106] (5) Cooling and curing: The fibers spun in step (4) are cooled and cured by a cooling device, and a continuous fiber web is formed after web laying; Specifically, the cooling and curing temperature drop in step (5) is 5℃ / min; the termination temperature after cooling and curing in step (5) is 25℃; and the ambient humidity during cooling and curing in step (5) is 60%.

[0107] (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; Specifically, the stretching parameters in step (6) are as follows: the stretching ratio is 1.2 times, the stretching temperature is 40℃, and the stretching speed is 80m / min; The thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 140℃, the roll pressure is 40N / mm, and the roll gap is 0.1mm.

[0108] (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. Specifically, the parameters of heat treatment in step (7) are as follows: temperature is 130℃, heat treatment time is 30s; The parameters of calendering in step (7) are as follows: calendering temperature is 100℃, calendering pressure is 20N / mm, calendering time is 2s, and calendering roller linear speed is 10m / min.

[0109] Scheme 5: The process of producing modified nonwoven fabric using recycled PP lunch box fragments includes the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with a modifier for later use; Specifically: The sorting steps in step (1) are as follows: Pour the PP lunch box fragments into clean water, stir and separate the floating PP lunch box fragments; The cleaning steps in step (1) are as follows: Put the sorted PP lunch box fragments into 80℃ hot water and stir to clean; The screening steps in step (1) are as follows: Use a crusher to control the size of the cleaned PP lunch box fragments to within 10mm.

[0110] The mass of the modified reinforcing agent added in step (1) is 15% of the PP lunch box fragments; The components of the modified reinforcing agent in step (1), by weight, include the following: 40 parts of glycine, 10 parts of azobisisobutyronitrile, and 25 parts of polyethylene glycol; The mixing pressure in step (1) is 4 MPa, and the mixing temperature is 75°C.

[0111] The preparation method of the nanocomposite material is as follows: Magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate are ground and mixed in a mass ratio of 5:5:6:8:6. Imidazole-4-carboxylic acid, which is 80 times the mass of the mixture, is added. The mixture is stirred and reacted at 90°C for 16 hours. The precipitate is repeatedly washed with anhydrous ethanol. Then, it is freeze-dried under vacuum at -80°C for 24 hours. The resulting powder is transferred to a high-temperature calcining furnace and calcined at 600°C for 13 hours under nitrogen atmosphere, with a heating rate of 10°C / min.

[0112] (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; specifically, the screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.6 times the screw diameter.

[0113] (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; The parameters of melt extrusion in step (3) are as follows: Zone 1: 220℃, Zone 2: 225℃, Zone 3: 230℃, Zone 4: 235℃, Zone 5: 240℃, Zone 6: 235℃.

[0114] (4) Spinning: The material molten and extruded in step (3) is extruded through a spinneret to form a filament; Specifically, the orifice diameter of the spinneret in step (4) is 0.4 mm; the temperature of the spinneret in step (4) is 300 °C; the spinning speed of the spinneret in step (4) is 3500 m / min; and the fineness range of the filament formed in step (4) is 2.5 dtex.

[0115] (5) Cooling and curing: The fibers spun in step (4) are cooled and cured by a cooling device, and a continuous fiber web is formed after web laying; Specifically, the cooling and curing temperature drop in step (5) is 5℃ / min; the termination temperature after cooling and curing in step (5) is 25℃; and the ambient humidity during cooling and curing in step (5) is 60%.

[0116] (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; Specifically, the stretching parameters in step (6) are as follows: the stretching ratio is 3.5 times, the stretching temperature is 60℃, and the stretching speed is 150m / min; The thermal bonding parameters in step (6) are as follows: the method is hot rolling, the roll temperature is 160℃, the roll pressure is 80N / mm, and the roll gap is 1.0mm.

[0117] (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. Specifically, the parameters of heat treatment in step (7) are as follows: temperature is 160℃, heat treatment time is 120s; The parameters of calendering in step (7) are as follows: calendering temperature is 140℃, calendering pressure is 100N / mm, calendering time is 10s, and calendering roller linear speed is -100m / min.

[0118] Test Procedure: The nonwoven fabrics prepared by the above schemes 1-5 shall be subjected to the following tests: tensile strength and elongation at break: GB / T 3923.1, tear strength: GB / T 3917.1, bursting strength: GB / T 19976, air permeability: GB / T 5453.

[0119] Table 1 Comprehensive Test As shown in the table above, the nonwoven fabric prepared by Scheme 3 exhibits the best performance in all performance indicators, including tensile strength, elongation at break, tear strength, bursting strength, and air permeability. Comparative analysis shows that Scheme 3 has the optimal preparation process while ensuring both the mechanical and air permeability properties of the nonwoven fabric.

[0120] Scheme 4, which does not use a modifier, exhibits the following tensile strength: Scheme 4 has a tensile strength significantly lower than the other schemes, at only 40.2 MPa, while the other schemes all exceed 45 MPa. This indicates that the modifier has a significant effect on improving the tensile strength of the material. Elongation at break: Scheme 4 has the lowest elongation at break at 360%, while the other schemes are all above 400%. The modifier can increase the ductility of the material. Tear strength: Scheme 4 has a tear strength of 245 N / mm, the lowest among all schemes. The modifier helps improve the tear resistance of the material. Bursting strength: Scheme 4 has a bursting strength of only 0.5 MPa, far lower than the other schemes. This shows that the modifier can significantly improve the impact resistance of the material. Air permeability: Scheme 4 has an air permeability of 1540 cm⁻¹. 3 / (m 2The pressure (0.1 MPa at 24h) is the lowest among all options. Modifying agents help form more microporous structures, thereby improving the material's air permeability. In summary, option 4, which does not use modifying agents, performs poorly in all performance indicators. The mechanisms of action of modifying agents include: enhancing intermolecular forces, improving the overall strength and toughness of the material; improving the arrangement and cross-linking degree of molecular chains, increasing the material's ductility; forming a more uniform microstructure, improving the material's tear and impact resistance; and introducing micropores or channels, improving the material's air permeability. The combined effect of these modifications makes the option with added modifying agents superior to option 4 in all performance indicators. This also demonstrates that modifying agents play a crucial role in the production of modified nonwoven fabrics using recycled PP lunchbox fragments, and are an important factor in improving product performance.

[0121] Scheme 5, which does not use nanocomposites, exhibits the following tensile strength: 45.9 MPa, lower than schemes 1-3 but higher than scheme 4. This indicates that nanocomposites can improve the tensile strength of the material by enhancing the interfacial bonding between the polymer matrix and fibers. Elongation at break: Scheme 5 has an elongation at break of 400%, lower than schemes 1-3. Nanocomposites improve elongation at break by enhancing the flexibility and ductility of the polymer chains. Tear strength: Scheme 5 has a tear strength of 257 N / mm, lower than schemes 1-3. Nanocomposites improve the tear resistance of the material by forming an energy dissipation mechanism in the microstructure. Bursting strength: Scheme 5 has a bursting strength of 0.7 MPa, lower than schemes 1-3. Nanocomposites improve bursting strength by enhancing the overall structural integrity and impact resistance of the material. Air permeability: Scheme 5 has an air permeability of 1620 cm⁻¹. 3 / (m 2(24h·0.1MPa), lower than schemes 1-3. Nanocomposites improve air permeability by forming micropores or changing fiber arrangement in the material. The mechanisms of action of nanocomposites include: Nanoscale effect: Due to their extremely small size, nanoparticles can be uniformly dispersed in the polymer matrix, providing a large interfacial area, thereby enhancing the overall performance of the material. Interfacial interaction: The strong interaction between nanoparticles and polymer molecular chains can improve the mechanical properties and thermal stability of the material. Structural regulation: Nanoparticles affect the crystallization behavior and microstructure of polymers, thereby changing the physical properties of the material. Multifunctionality: Different types of nanoparticles can endow materials with specific functions, such as enhancing mechanical properties and improving flame retardancy. Pore structure regulation: Nanoparticles affect the pore structure of the material, thereby affecting air permeability and other related properties. In general, the addition of nanocomposites significantly improves the comprehensive performance of nonwoven fabrics. Although scheme 5 still shows good performance without the use of nanocomposites, all indicators are lower compared with the schemes using nanocomposites. This highlights the important role of nanocomposites in the preparation of modified nonwoven fabrics.

[0122] In addition, a test was conducted to kill airborne bacteria by mixing 1g of nonwoven fabric with 10mL of 10 6 A mixture of CFU / mL *E. coli* (*E. coli* O157:H7) bacterial suspensions was added, followed by the addition of a 10 mM hydrogen peroxide solution (the nanocomposite material can catalyze the generation of hydroxyl radicals from a small amount of hydrogen peroxide solution to achieve a bactericidal effect). The mixture was incubated for 1 hour, and then plate-diluted and counted. As shown in Figure 5, Scheme 3 achieved a bactericidal rate of 99.6%, while Schemes 1 and 2 achieved bactericidal rates of 80.9% and 91.4%, respectively. Schemes 4 and 5, however, achieved bactericidal rates of only 1.1% and 22.4%, respectively, which were almost ineffective.

[0123] Recommendations for future research: Establish quality control standards for recycled PP food container fragments: Size requirements: The size of the fragments should be controlled between 5-10mm. If they are too large, it will affect the uniformity of melting; if they are too small, they will easily generate dust.

[0124] Impurity content: Light impurities such as wood chips and paper scraps ≤0.05%, heavy impurities such as metals ≤0.01%.

[0125] Moisture content: ≤0.3%. Excessive moisture content can lead to the generation of water vapor in the melt, affecting the spinning quality.

[0126] Odor: The crushed pieces should be odorless; if necessary, high-temperature deodorization treatment should be performed.

[0127] The optimized crushing process adopts a two-stage crushing method: coarse crushing (20-30mm) + fine crushing (5-10mm) to reduce dust generation.

[0128] Metal detection and dust removal are performed simultaneously during the crushing process to improve the purity of the crushed material.

[0129] Surface modification of the crushed material can be performed as needed, such as plasma treatment, to improve its compatibility with PP.

[0130] Depending on quality requirements, the proportion of recycled PP fragments can be 30-70% and blended with virgin PP.

[0131] Appropriate compatibilizers, such as maleic anhydride-grafted PP, can be added to improve melt uniformity.

[0132] If necessary, toughening agents, nucleating agents, and other additives can be added to improve the mechanical properties of the product.

[0133] The melt extrusion process was optimized by using a twin-screw extruder to improve the dispersion and mixing effect of crushed materials.

[0134] Optimize the design of screw assembly components, such as using multiple sets of dispersion discs, to enhance melt homogenization.

[0135] Increase back pressure to refine the melt flow channel and suppress bubbles generated by crushed material.

[0136] Optimize the spinning process to reduce the spinning temperature and minimize the thermal degradation of broken PP.

[0137] A high-efficiency filtration system is used to reduce the clogging of the spinneret by impurities from crushed material.

[0138] Optimize cooling and drawing conditions to improve fiber orientation and uniformity.

[0139] The optimized web laying and forming process employs multiple web heads to improve the uniformity of the fiber web.

[0140] Optimize hot rolling temperature and pressure, and appropriately reduce them when crushing PP products with low melting points.

[0141] After hot rolling, online dust removal is used to remove dust particles from the surface of the fiber web.

[0142] Strengthen quality inspection and establish a quality inspection system for raw materials, semi-finished products and finished products.

[0143] We focus on key indicators such as fiber diameter, strength, and uniformity.

[0144] Surface quality, feel, and odor are rigorously evaluated.

[0145] By optimizing the above production processes, high-quality spunbond nonwoven fabric can be produced by fully utilizing recycled PP lunch box scraps. This reduces raw material costs, achieves the recycling of plastic resources, and promotes the green and sustainable development of the industry.

[0146] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for preparing modified nonwoven fabric using recycled PP lunchbox fragments, comprising the following steps: (1) Raw material preparation: The recycled PP lunch box fragments are sorted, cleaned and screened, and then mixed with the modifier and strengthening agent for later use; (2) Feeding and conveying: A screw feeder is used to convey the raw materials prepared in step (1) to the screw extruder; (3) Screw extrusion: The raw material from step (2) is melt-extruded using a screw extruder; (4) Spinning and forming: The material molten and extruded in step (3) is extruded through a spinneret and spun into fibers; (5) Cooling and solidification: The fibers spun in step (4) are cooled and solidified by a cooling device, and a continuous fiber web is formed after web laying. (6) Stretching and reinforcement: The fiber web obtained in step (5) is stretched and then thermally bonded to form a nonwoven fabric with the required physical properties after web laying; (7) Post-processing: The nonwoven fabric obtained in step (6) is subjected to heat treatment and calendering. The sorting steps in step (1) are as follows: Pour the PP lunch box fragments into clean water, stir, and then separate the floating PP lunch box fragments; The cleaning steps in step (1) are as follows: put the sorted PP lunch box fragments into hot water at 60℃-80℃ and stir to clean them; The screening steps in step (1) are as follows: the size of the shredded PP lunch box after cleaning is controlled to be within 10mm by using a crusher; In step (1), the added mass of the modifier and reinforcing agent is 10%-15% of the PP lunch box fragments; The components of the modifier in step (1), by weight, include the following: 25-40 parts of glycine 10-20 parts of nanocomposite material 5-10 parts of azobisisobutyronitrile (AIBN) 15-25 parts polyethylene glycol; The mixing pressure in step (1) is 2MPa-4MPa, and the mixing temperature is 65℃-75℃; The preparation method of the aforementioned nanocomposite material is as follows: The mixture of magnesium nitrate, ferrous sulfate, gadolinium nitrate, manganese nitrate, and cobalt triacetylacetonate was ground and mixed in a mass ratio of (1-5):(1-5):(3-6):(2-8):(1-6). Imidazole-4-carboxylic acid was added at 50-80 times the mass of the mixture. The mixture was stirred and reacted at 80-90℃ for 8-16 hours. The precipitate was repeatedly washed with anhydrous ethanol. Then, it was freeze-dried under vacuum at -80℃ for 24 hours. The resulting powder was transferred to a high-temperature calcining furnace and calcined at 400-600℃ under nitrogen atmosphere for 9-13 hours, with a heating rate of 10℃ / min.

2. The modified nonwoven fabric preparation process using recycled PP lunch box fragments as described in claim 1, characterized in that: The screw feeder mentioned in step (2) is a screw conveyor with a screw pitch of 0.5 to 0.6 times the screw diameter.

3. The process for preparing modified nonwoven fabric using recycled PP lunchbox fragments according to claim 1, characterized in that: The parameters for melt extrusion in step (3) are as follows: Zone 1: 215-225℃ Zone 2: 220-230℃ Zone 3: 225-235℃ Zone 4: 230-240℃ Zone 5: 235-245℃ Zone 6: 230-240℃.

4. The process for preparing modified nonwoven fabric using recycled PP lunchbox fragments according to claim 1, characterized in that: In step (4), the orifice diameter of the spinneret is 0.2-0.4 mm; In step (4), the temperature of the spinneret is 280-300℃; In step (4), the spinning speed of the spinneret is 1500-3500 m / min; The fineness range of the spun fibers in step (4) is 1.0-2.5 dtex.

5. The process for preparing modified nonwoven fabric using recycled PP lunchbox fragments according to claim 1, characterized in that: In step (5), the cooling and solidification process involves a temperature drop of 5°C / min. The termination temperature after cooling and curing in step (5) is 25℃; The ambient humidity during cooling and curing in step (5) is 60%.

6. The process for preparing modified nonwoven fabric using recycled PP lunchbox fragments according to claim 1, characterized in that: The drawing parameters in step (6) are as follows: The draw ratio is 1.2-3.5 times, the draw temperature is 40-60℃, and the draw speed is 80-150m / min; The parameters for hot bonding in step (6) are as follows: The rolling process is hot rolling, with a roll temperature of 140-160℃, a roll pressure of 40-80 N / mm, and a roll gap of 0.1-1.0 mm.

7. The process for preparing modified nonwoven fabric using recycled PP lunchbox fragments according to claim 1, characterized in that: The parameters for heat treatment in step (7) are as follows: The temperature is 130-160℃, and the heat treatment time is 30-120s; The parameters for the calendering process in step (7) are as follows: The calendering temperature is 100-140℃, the calendering pressure is 20-100N / mm, the calendering time is 2-10s, and the linear speed of the calendering roller is 10-100m / min.

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