High-breaking-strength regenerated fiber and preparation method thereof

Abstract

The invention relates to a high-breaking-strength regenerated fiber and a preparation method thereof, and relates to the field of fiber preparation. A preparation method of regenerated fibers with high breaking strength comprises the following steps: pre-crystallizing clean recycled PET bottle flakes, and then drying and crystallizing to obtain crystallized PET bottle flakes; carrying out melt extrusion on the crystallized PET bottle flakes, and filtering in the extrusion process to obtain raw material PET particles; the preparation method comprises the following steps: melting raw material PET particles, adding other raw materials in the melting process, and mixing to obtain modified PET; sequentially pressurizing and metering the modified PET, and then carrying out spinning treatment to obtain spun yarns; spinning is pre-interlaced and then enters a hot roller to be drafted, and then interlaced winding forming is carried out. The melt is deeply filtered by reducing the particle size of the metal sand, residual tiny impurities and other foreign matter are intercepted, meanwhile, the pressure setting of the booster pump is improved, the melt fully permeates into gaps of the metal sand, the spinning end breakage rate is reduced, and continuity is guaranteed.

Description

Technical Field

[0001] This application relates to the field of recycling and processing waste PET, and in particular to a high breaking strength recycled fiber and its preparation method. Background Technology

[0002] With global resource scarcity and increasing environmental awareness, the recycling and reuse of waste polymer materials has become an important issue in the circular economy. Polyester (polyethylene terephthalate, PET), as a synthetic polymer material widely used in packaging, textiles, engineering plastics, and other fields, makes the recycling and treatment of its waste products (such as PET beverage bottles, textile waste, etc.) particularly crucial.

[0003] In related technologies, the recycling and processing technology for waste PET mainly involves sorting and cleaning the waste materials before directly performing melt spinning. This method has low processing costs, but the PET bottle flake melt contains a large number of impurities, resulting in decreased melt uniformity and consequently, poorer mechanical properties of the finished product, thus limiting its application areas. Summary of the Invention

[0004] To address the issue of poor mechanical properties in products directly obtained by melt spinning recycled PET bottle flakes, this application provides a high-breaking-strength recycled fiber and its preparation method.

[0005] In a first aspect, this application provides a method for preparing high-tensile-strength regenerated fibers, employing the following technical solution: A method for preparing high-tensile-strength regenerated fibers includes the following steps: S1. Clean recycled PET bottle flakes are pre-crystallized and then dried and crystallized to obtain crystalline PET bottle flakes; S2: Melt and extrude crystalline PET bottle flakes, filtering them simultaneously during the process to obtain raw PET granules; S3: After melting the raw material PET granules, add other raw materials and mix to obtain modified PET; S4: Modified PET is sequentially subjected to pressure and metering before spinning to form spun fibers; S5: The spinning process involves pre-networking, followed by drawing and then network winding to obtain the finished product; The weight of recycled PET bottle flakes in S1 is 1000 parts; The other raw materials in S3 include the following components in parts by weight: 20-30 parts of nanofiller and 3-4 parts of phenyl silicone oil.

[0006] By adopting the above technical solution, the pre-crystallization and drying crystallization steps in S1 and the melt extrusion filtration steps in S2 effectively remove moisture and mechanical impurities from the recycled bottle flakes, thereby improving the purity of the raw material PET particles.

[0007] The small size effect and high specific surface area of ​​nanofillers can form a good interfacial bond with the PET matrix, inhibit the slippage of PET molecular chains, improve the rheology of the melt, and reduce the problem of poor melt uniformity caused by impurities in recycled PET bottles. Nanofillers can also bear some external forces, hinder crack propagation, make up for the poor tensile strength of recycled PET caused by impurities, and improve the mechanical stability of the finished product.

[0008] The phenyl silicone oil molecular chain contains nonpolar silicon-oxygen chains and weakly polar phenyl groups, which can physically adsorb and coat the surface of nanofillers, reducing their surface energy and decreasing the attraction between particles. This inhibits agglomeration, allowing the nanoparticles to be dispersed in the PET matrix in a finer and more uniform state. Simultaneously, it avoids clogging of the spinning components during the spinning process due to nanofiller agglomeration. Furthermore, phenyl silicone oil possesses a certain degree of flexibility, enabling it to synergistically balance the toughness and rigidity of the fibers with the nanofillers.

[0009] Preferably, the spinning process in S4 is carried out by a spinning assembly, which includes a housing, a spinneret, a flow divider, a filter ring, a feed head, and a cap. The spinneret, flow divider, filter ring, and feed head are sequentially embedded in the housing. The cap is threaded to the end of the housing away from the spinneret. The filter ring is filled with metal sand.

[0010] By adopting the above technical solution, the metal sand filling the filter chamber ring has a porous structure and a large specific surface area, which can serve as a deep filtration medium to further filter the modified PET melt entering the spinning assembly. This traps residual minute mechanical impurities and other foreign matter in the melt, preventing clogging of the spinneret orifices and thus reducing the breakage rate during spinning, ensuring spinning continuity. The metal sand also forms a synergistic "dual filtration" effect with the melt extrusion filtration of S2, further improving melt purity and ensuring the subsequent spinning of uniform and stable fibers.

[0011] The spinning assembly ensures that the melt is ejected from the spinneret at a stable pressure and flow rate through precise filtration of metal sand and uniform flow distribution by the diverter plate, which can effectively reduce fiber performance differences caused by process fluctuations.

[0012] Preferably, the particle size of the metal sand is 90-110 mesh.

[0013] By adopting the above technical solution, when the particle size of the metal sand is too small, the gaps between the small-diameter metal sand particles are easily blocked by tiny impurities in the melt, and it is difficult to clean after blockage. The filtration capacity will drop rapidly, and it will be unable to effectively intercept impurities. Ultimately, impurities will enter the spinneret, causing spinneret hole blockage and an increase in the breakage rate. When the particle size of the metal sand is too large, the gaps between the large-diameter metal sand particles are too large, and it is impossible to effectively intercept the fine impurities in the melt. These impurities will enter the spinneret with the melt, block the spinneret holes, or cause filament breakage and filament drift during the spinning process, reduce the continuity of spinning, and affect the mechanical properties of the regenerated fiber.

[0014] Preferably, the pressure of the booster pump in S4 is set to 140-160 MPa.

[0015] By adopting the above technical solution, the flow of the melt in the filter chamber ring (including metal sand) depends on sufficient pressure. If the pressure setting of the booster pump is too low, the contact between the melt and the filter medium and the flow distribution structure will be insufficient. The melt cannot fully penetrate the gaps of the metal sand, and small impurities may not be effectively intercepted due to insufficient power, increasing the risk of spinneret blockage.

[0016] When the pressure of the booster pump is set too high, the excessive pressure will cause the melt to be subjected to severe shear force in the pipeline and spinning assembly. The molecular chains of the modified melt of recycled PET may be unstable due to the presence of impurities, and strong shear can easily lead to the breakage of PET molecular chains.

[0017] Preferably, the nanofiller comprises silicon dioxide and titanium dioxide.

[0018] Preferably, the mass ratio of silicon dioxide to titanium dioxide is 2:(0.8-1).

[0019] By adopting the above technical solution, nano-silica can effectively anchor PET molecular chains, inhibit the agglomeration of impurities such as PVC in recycled PET caused by molecular chain sliding, reduce the formation of large-sized impurity particles in the melt, and at the same time capture some tiny impurities with particle sizes smaller than the gaps between metal sands through physical adsorption, thus performing "pre-filtration" before deep filtration of metal sands.

[0020] The particle morphology of nano titanium dioxide (mostly spherical or near-spherical) can reduce the internal frictional resistance of PET melt flow, making the melt more evenly distributed in the gaps between the metal sands in the filter chamber ring, so that the filtration area of ​​the metal sands is fully utilized and the stability of the filtration effect is improved.

[0021] Nano-silica and titanium dioxide can work together with metal sand to achieve "raw material optimization-flow control-physical filtration", ensuring spinning continuity and enhancing the mechanical properties of regenerated fibers.

[0022] Preferably, the phenyl silicone oil is one of epoxy-modified phenyl silicone oil and hydroxyl-terminated phenyl silicone oil.

[0023] Preferably, the phenyl silicone oil is an epoxy-modified phenyl silicone oil.

[0024] By adopting the above technical solution, the epoxy group in the epoxy-modified phenyl silicone oil can undergo a ring-opening reaction with the hydroxyl group at the end of the PET molecular chain to form a chemical covalent bond, and the hydroxyl group of the terminal hydroxyl phenyl silicone oil can form a hydrogen bond with the ester group or hydroxyl group in the PET molecular chain, thereby anchoring the phenyl silicone oil molecule more firmly in the PET matrix and inhibiting its migration to form a surface silicone oil film.

[0025] The formation of covalent bonds between epoxy-modified silicone oil and PET requires a certain amount of energy to trigger the ring-opening of the epoxy group. The hydroxyl groups on the surface of silica and titanium dioxide can act as "proton donors" to interact with the oxygen atoms of the epoxy group, weakening the stability of the epoxy ring, reducing the activation energy of the ring-opening reaction, and accelerating the formation of covalent bonds.

[0026] Covalent bonds have a stronger binding force than hydrogen bonds, which makes the bond between phenyl silicone oil and PET matrix more stable. Therefore, epoxy-modified silicone oil is preferred.

[0027] Preferably, the preparation method of the epoxy-modified phenyl silicone oil includes the following steps: A. Add hydrogen-terminated phenyl silicone oil and allyl glycidyl ether to a xylene solution, stir until homogeneous, continue stirring and add diluted platinum catalyst dropwise to obtain a mixed solution; B. Introduce nitrogen gas into the mixed solution and raise the temperature to 60-70°C. Stir the reaction continuously for 30 minutes to obtain the initial reaction solution. C. Continue to purge nitrogen gas into the initial reaction solution and heat it to 140-155°C. Stir continuously and evacuate for 2-3 hours to remove low-boiling substances. Then, purge nitrogen gas to cool it to room temperature and stop stirring to obtain the final product. In step A, the mass ratio of terminal hydrogen-containing phenyl silicone oil to allyl glycidyl ether is 10:(1-2).

[0028] Secondly, this application provides a high-tensile-strength recycled fiber, employing the following technical solution: A high breaking strength regenerated fiber is prepared by the above-mentioned method for preparing high breaking strength regenerated fiber.

[0029] In summary, this application has the following beneficial effects: 1. This application effectively improves the purity of raw material PET particles through the pre-crystallization and drying crystallization steps in S1 and the melt extrusion filtration step in S2; the nanofiller improves the rheology of the melt, reduces uniformity problems, and at the same time bears external forces, hinders crack propagation, and makes up for the tensile strength defects of recycled PET; phenyl silicone oil inhibits the agglomeration of nanofiller, avoids clogging of spinning components, and at the same time works with nanofiller to balance the toughness and rigidity of the fiber. 2. This application achieves deep filtration of the melt by reducing the particle size of the metal sand filling the filter chamber ring, thereby trapping residual micro-impurities and other foreign matter to avoid clogging the spinneret orifice. At the same time, it increases the pressure setting of the booster pump to allow the melt to fully penetrate the gaps between the metal sand, thereby reducing the spinning breakage rate and ensuring continuity. 3. The epoxy-modified phenyl silicone oil of this application can undergo a ring-opening reaction with PET to form chemical covalent bonds, thereby anchoring the phenyl silicone oil molecules in the PET matrix. At the same time, the hydroxyl groups on the surface of silicon dioxide and titanium dioxide can act as "proton donors" to weaken the stability of the epoxy ring, reduce the activation energy of the ring-opening reaction, and accelerate the formation of covalent bonds. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a half-section structure of the spinning assembly in an embodiment of this application.

[0031] Explanation of reference numerals in the attached drawings: 1. Shell; 2. Spinneret; 3. Diverter plate; 4. Filter ring; 41. Metal sand; 5. Slurry inlet head; 6. Pressure cap. Detailed Implementation

[0032] The raw materials in this application include the following: PET bottle flakes recycling: The waste bottles recycled by our company contain 5-8 wt% PVC impurities; Hydrogen-terminated phenyl silicone oil: Commercially available product IOTA234 manufactured by Anhui Aiyota Silicone Oil Co., Ltd. Allyl glycidyl ether: Use commercially available products with CAS number 106-92-3; Methylphenyl dichlorosilane: Use commercially available products with CAS number 149-74-6; Dimethyldichlorosilane: Use commercially available products with CAS number 75-78-5; Preparation Example 1 A method for preparing epoxy-modified phenyl silicone oil includes the following steps: A. Add 60g of hydrogen-terminated phenyl silicone oil and 10g of allyl glycidyl ether to a xylene solution, stir until homogeneous, continue stirring (100 rpm), and add diluted platinum catalyst dropwise to obtain a mixed solution; B. Introduce nitrogen gas into the mixed solution and heat it to 60°C. Maintain the temperature at 60-70°C and stir continuously (900 rpm) for 30 minutes to obtain the initial reaction solution. C. Continue to introduce nitrogen gas into the initial reaction solution and heat it to 140°C. Maintain the temperature at 140-155°C, stir continuously (250 rpm), and evacuate for 2-3 hours, maintaining a vacuum of -0.099 MPa to remove low-boiling substances. Then, cool the solution to room temperature by introducing nitrogen gas and stop stirring to obtain epoxy-modified phenyl silicone oil.

[0033] Preparation Example 2 The preparation method of hydroxyl-terminated phenyl silicone oil includes the following steps: (a) Mix 175g of toluene and 200g of water thoroughly to obtain a mixed solution; (b) At 20°C, 75 g of methylphenyl dichlorosilane and 150 g of dimethyl dichlorosilane were added dropwise to the mixed solution over 2 hours to obtain the mixed solution; (c) The oil layer of the mixture is washed with a 10 wt% NaOH solution until neutral, the water layer of the mixture is separated by standing, and then the oil layer is heated to 90°C and dehydrated and desolventized under vacuum to obtain a hydrolysate containing methylphenylsiloxane linkages. (d) Mix 100g of hydrolysate, 40g of acetic anhydride and 2g of concentrated sulfuric acid evenly, heat to 140℃ and stir for 5h, cool and let stand, then wash with water with 20wt% soda ash solution until neutral, heat to 65℃ and stir for 4h, let stand to separate the water layer, and obtain crude product. (e) The crude product oil layer is dehydrated with 2g of calcium chloride and then decolorized with 0.5g of activated carbon to obtain terminal hydroxyl phenyl silicone oil.

[0034] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0035] Example 1 A method for preparing high breaking strength regenerated fiber includes the following steps: S1. The recycled waste bottles are cleaned and crushed to obtain crystalline PET bottle flakes; 1000g of clean PET bottle flakes are fed into the crystallization bed and pre-crystallized under the action of hot air at 170℃ to remove a large amount of surface moisture. Then the pre-crystallized bottle flakes are sent into the drying device and dried at 150℃ for 6 hours to obtain crystalline PET bottle flakes. S2. Crystalline PET bottle flakes are continuously fed into a screw mixer via a feeding device for melt extrusion. The heating zones of the screw mixer are as follows: Zones 1-6, 280℃; Zones 7-10, 270℃; and the cooling zone temperature is 30℃. During extrusion, a three-way valve filter with no dead zones is used for melt filtration. The melt is diverted within the filter to achieve first-in-first-out and no dead zones. The internal light intensity is 0.5, the filter temperature is 290℃, the filtration accuracy is 25μm, and the filtration area is 4m². 2 This process yields raw material PET granules. S3. The obtained raw material PET granules are continuously fed into a screw mixer via a feeding device for remelting. The temperature settings of each heating zone of the screw mixer are the same as in step S2. During the melting process, 17g of nano silica, 8g of nano titanium dioxide and 3.5g of phenyl silicone oil are added, and nitrogen gas is introduced under the melt for blowing for 6 hours. The mixture is mixed and low-boiling substances are removed to obtain modified PET. S4. The modified PET is spun sequentially through a booster pump, a metering pump, and a spinning assembly to obtain spun fibers; the pressure of the booster pump is set to 150 MPa; refer to... Figure 1 The spinning assembly includes a housing 1, a spinneret 2, a flow divider 3, a filter chamber ring 4, a slurry inlet head 5, and a pressure cap 6. The spinneret 2, the flow divider 3, the filter chamber ring 4, and the slurry inlet head 5 are sequentially embedded in the housing 1. The pressure cap 6 is threaded to the end of the housing 1 away from the spinneret 2. The filter chamber ring 4 is filled with metal sand 41, and the particle size of the metal sand 41 is 100 mesh. S5. After the spun yarn passes through the pre-network, it enters the hot roller zone for stretching treatment. The stretching bath temperature is 70℃, the steam box temperature is 105℃, the relaxation heat setting temperature is 150℃, and the stretching speed is 150m / min. After stretching to the FDY standard under the action of the first hot roller temperature of 100℃ and the second hot roller temperature of 140℃, it is networked and wound into shape at a speed of 3200m / min to obtain high breaking strength regenerated fiber.

[0036] Examples 2-4 Examples 2-4 are based on the preparation method of Example 1, but the amounts of nano-silica, nano-titanium dioxide and phenyl silicone oil are adjusted, as shown in Table 1.

[0037] Comparative Examples 1-3 Comparative Examples 1-3 were prepared based on the method in Example 1, with adjustments made to the amounts of nano-silica, nano-titanium dioxide, and phenyl silicone oil, as shown in Table 1.

[0038] Table 1. Raw material list and performance test table for Examples 1-4 and Comparative Examples 1-2 Performance testing: The high breaking strength regenerated fibers prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to the following performance tests, and the test results are shown in Table 1.

[0039] (1) Elongation at break The tensile properties test method described in GB / T14344-2003 is used to test the sample. After removing the surface layer of the sample after moisture conditioning and equilibration, take a sample (more than 60 cm in length), clamp both ends to prevent loss of twist, immerse it in distilled water at (20±2)℃ for 2 minutes, start the tensile testing machine and let it run under the specified conditions, and determine the test value of the elongation at break performance index from the data acquisition system.

[0040] (2) Fracture strength The fracture strength test method described in GB / T14344-2001 was carried out. After removing the outer tens of meters of the sample after moisture conditioning and balancing, it was placed on the cylinder frame of the automatic tensile testing machine, and the wire end was inserted into the clamping device of the tensile testing machine. The clamping device automatically clamped the sample and clamped both ends of the sample into the upper and lower clamps. The tensile testing machine was started and allowed to run under the specified conditions. The test value was determined from the data acquisition system.

[0041] Referring to Table 1, it can be seen from the comparison between Examples 1-4 and Comparative Examples 1-3 that the fiber performance of Examples 1-4 is better than that of Comparative Examples 1-3. This is because Comparative Example 1 did not add nano-silica and nano-titanium dioxide, and could not improve the rheology of PET melt by means of the small size effect and high specific surface area of ​​nanofillers. At the same time, it lacked the role of nanofillers in bearing external forces and hindering crack propagation, so the defects of poor tensile strength caused by impurities in recycled PET could not be compensated, and the mechanical stability of the finished product decreased significantly.

[0042] In Comparative Example 2, without the addition of phenyl silicone oil, the nanofiller is prone to agglomeration, making it difficult to disperse in the PET matrix in a fine and uniform state. During the spinning process, the agglomeration can easily clog the spinning components, and the synergistic effect of phenyl silicone oil and nanofiller in balancing the toughness and rigidity of the fiber is lost, resulting in an imbalance in the mechanical properties of the finished product.

[0043] Comparative Example 3, without the addition of nano-silica, nano-titanium dioxide, and phenyl silicone oil, did not improve the negative impact of impurities in the recycled PET itself on melt rheology, uniformity, tensile strength, and mechanical stability of the finished product. At the same time, the spinning process was also prone to clogging due to the presence of various impurities, ultimately leading to deterioration of the finished product's performance.

[0044] In comparison, the high breaking strength regenerated fiber of Example 1 has the best overall performance. This is because nano-silica and titanium dioxide can work together with metal sand to achieve "raw material optimization-flow control-physical filtration", ensuring spinning continuity and enhancing the mechanical properties of the regenerated fiber. Therefore, Example 1 is preferred.

[0045] Examples 5-8 Examples 5-8 are based on the preparation method of Example 1, but the particle size of the metal sand used in S4 is adjusted, as shown in Table 2.

[0046] The high breaking strength regenerated fibers prepared in Examples 5-8 were subjected to the above performance tests, and the test results are shown in Table 2.

[0047] Table 2. Particle size and performance test results of the metal sand in Examples 1 and 5-8. Referring to Table 2, a comparison of Examples 1 and 5-8 shows that both excessively small and excessively large particle sizes of metal abrasive are detrimental to improving the mechanical properties of fibers. This is because the gaps between small-diameter metal abrasive particles are easily clogged by tiny impurities in the melt, causing a rapid decrease in filtration capacity and an inability to effectively trap impurities. Ultimately, impurities enter the spinneret, resulting in spinneret hole blockage and an increased breakage rate. Conversely, the larger gaps between large-diameter metal abrasive particles prevent effective trapping of fine impurities in the melt. These impurities, entering the spinneret with the melt, can clog the spinneret holes or cause fiber breakage and filament drift during spinning, affecting the performance of the finished product.

[0048] Examples 9-12 Examples 9-12 are based on the preparation method of Example 1, but the pressure setting of the booster pump in S4 is adjusted, as shown in Table 3.

[0049] The high breaking strength regenerated fibers prepared in Examples 9-12 were subjected to the above performance tests, and the test results are shown in Table 3.

[0050] Table 3. Pressure settings and performance testing of the booster pumps in Examples 1 and 9-12. Referring to Table 3, a comparison of Examples 1 and 9-12 shows that both excessively low and excessively high pressures are detrimental to improving the mechanical properties of the fibers. This is because the flow of the melt in the filter ring (containing metal sand) depends on sufficient pressure. When the pressure is too low, the melt cannot fully penetrate the gaps of the 100-mesh metal sand, and small impurities may not be effectively intercepted due to insufficient power, thus entering the finished product and affecting its performance. Excessively high pressure will cause the melt to be subjected to severe shearing forces in the pipes and spinning components. Strong shearing can easily lead to the breakage of PET molecular chains, thereby causing a decrease in the mechanical properties of the regenerated fibers.

[0051] Examples 13-16 Examples 13-16 are based on the preparation method of Example 1, with the total mass of nano-silica and nano-titanium dioxide kept at 25g, and the mass ratio of nano-silica and nano-titanium dioxide is adjusted as shown in Table 4.

[0052] The high breaking strength regenerated fibers prepared in Examples 13-16 were subjected to the above performance tests, and the test results are shown in Table 4.

[0053] Table 4. Mass ratio and performance test results of nano-silica and nano-titanium dioxide in Examples 1 and 13-16. Referring to Table 4, a comparison of Examples 1 and 13-16 shows that both excessively low and excessively high amounts of nano-titanium dioxide are detrimental to improving the mechanical properties of the fiber. This is because when there is too little nano-titanium dioxide, it is difficult to fully exert its "flow regulation" function to ensure spinning continuity and enhance the mechanical properties of the regenerated fiber. When there is too much nano-titanium dioxide, due to its photocatalytic properties, its photocatalytic effect may be over-excited under light conditions, causing partial degradation of the PET molecular chain.

[0054] Examples 17-18 Example 17 is based on the preparation method of Example 1, except that the phenyl silicone oil added in S3 is replaced with the epoxy-modified phenyl silicone oil prepared in Preparation Example 1, and the other conditions remain unchanged.

[0055] Example 18 is based on the preparation method of Example 1, except that the phenyl silicone oil added in S3 is replaced with the hydroxyl-terminated phenyl silicone oil prepared in Preparation Example 2, while the other conditions remain unchanged.

[0056] Performance testing: The high breaking strength regenerated fibers prepared in Examples 1 and 17-18 were subjected to the following performance tests, and the test results are shown in Table 5.

[0057] Blooming resistance stability test: A 15cm long high breaking strength regenerated fiber sample was placed in a constant temperature and humidity chamber with a temperature of 50±2℃ and a relative humidity of 85±5% for 14 days. After removal, the fiber surface was observed under natural light to see if there was white powder, oil spots or changes in gloss.

[0058] Table 5 Performance test results for Examples 1 and 17-18 Referring to Table 5, a comparison of Example 1 and Examples 17-18 shows that the bloom resistance of Examples 17-18 is better than that of Example 1. This is because the epoxy groups in the epoxy-modified phenyl silicone oil can undergo a ring-opening reaction with the hydroxyl groups at the end of the PET molecular chain to form chemical covalent bonds, while the hydroxyl groups of the terminal hydroxyl phenyl silicone oil can form hydrogen bonds with the ester groups or hydroxyl groups in the PET molecular chain, thereby anchoring the phenyl silicone oil molecules more firmly in the PET matrix and inhibiting their migration to form a surface silicone oil film.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing high-tensile-strength regenerated fiber, characterized in that, Includes the following steps: S1. Clean recycled PET bottle flakes are pre-crystallized and then dried and crystallized to obtain crystalline PET bottle flakes; S2: Melt and extrude crystalline PET bottle flakes, filtering them simultaneously during the process to obtain raw PET granules; S3: After melting the raw material PET granules, add other raw materials and mix to obtain modified PET; S4: Modified PET is sequentially subjected to pressure and metering before spinning to form spun fibers; S5: The spinning process involves pre-networking, followed by drawing and then network winding to obtain the finished product; The weight of recycled PET bottle flakes in S1 is 1000 parts; The other raw materials in S3 include the following components in parts by weight: 20-30 parts of nanofiller and 3-4 parts of phenyl silicone oil.

2. The method for preparing high breaking strength regenerated fiber according to claim 1, characterized in that: The spinning process in S4 is carried out by a spinning assembly, which includes a housing (1), a spinneret (2), a flow divider (3), a filter ring (4), a feed head (5), and a cap (6). The spinneret (2), the flow divider (3), the filter ring (4), and the feed head (5) are sequentially embedded in the housing (1). The cap (6) is threaded to the end of the housing (1) away from the spinneret (2). The filter ring (4) is filled with metal sand (41).

3. The method for preparing high breaking strength regenerated fiber according to claim 2, characterized in that: The particle size of the metal sand is 90-110 mesh.

4. The method for preparing high breaking strength regenerated fiber according to claim 1, characterized in that: The pressure of the booster pump described in S4 is set to 140-160 MPa.

5. The method for preparing high breaking strength regenerated fiber according to claim 1, characterized in that: The nanofillers include silicon dioxide and titanium dioxide.

6. The method for preparing high breaking strength regenerated fiber according to claim 5, characterized in that: The mass ratio of silicon dioxide to titanium dioxide is 2:(0.8-1).

7. The method for preparing high breaking strength regenerated fiber according to claim 1, characterized in that: The phenyl silicone oil is one of epoxy-modified phenyl silicone oil and hydroxyl-terminated phenyl silicone oil.

8. The method for preparing high breaking strength regenerated fiber according to claim 7, characterized in that: The phenyl silicone oil is an epoxy-modified phenyl silicone oil.

9. The method for preparing high-tensile-strength regenerated fiber according to claim 7, characterized in that, The preparation method of the epoxy-modified phenyl silicone oil includes the following steps: A. Add hydrogen-terminated phenyl silicone oil and allyl glycidyl ether to a xylene solution, stir until homogeneous, continue stirring and add diluted platinum catalyst dropwise to obtain a mixed solution; B. Introduce nitrogen gas into the mixed solution and raise the temperature to 60-70°C. Stir the reaction continuously for 30 minutes to obtain the initial reaction solution. C. Continue to purge nitrogen gas into the initial reaction solution and heat it to 140-155°C. Stir continuously and evacuate for 2-3 hours to remove low-boiling substances. Then, purge nitrogen gas to cool it to room temperature and stop stirring to obtain the final product. In step A, the mass ratio of terminal hydrogen-containing phenyl silicone oil to allyl glycidyl ether is 10:(1-2).

10. A high-tensile-strength recycled fiber, characterized in that: It is prepared by the method of any one of claims 1-9 for high breaking strength regenerated fiber.

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