A multifunctional polyester staple fiber and its preparation method

Abstract

This invention relates to a multifunctional polyester staple fiber and its preparation method, belonging to the field of functional fiber technology. The preparation method of this invention includes the following steps: S1, mixing recycled polyester from bottle flakes with hollow mesoporous silica microspheres to obtain component I; S2, mixing membrane-derived recycled polyester with octyl polytrimethylsiloxane to obtain component II; S3, performing composite spinning on component I and component II to obtain multifunctional polyester staple fiber. Using recycled polyester from bottle flakes and membrane-derived recycled polyester as substrates, through parallel composite spinning combined with hollow mesoporous silica microspheres and octyl polytrimethylsiloxane modification, a stable three-dimensional crimp structure is formed by utilizing the difference in thermal shrinkage between the two components. This simultaneously endows the fiber with comprehensive properties such as high bulkiness, excellent compression resilience, high-efficiency warmth retention in both dry and wet states, and moisture resistance, achieving stable spinning and functional upgrading of various types of recycled polyester materials.

Description

Technical Field

[0001] This invention belongs to the field of functional fiber technology, and in particular relates to a multifunctional polyester staple fiber and its preparation method. Background Technology

[0002] The global outdoor sports, cold chain logistics, and home textile markets for high-altitude and cold-weather applications continue to expand, driving core demand for lightweight, warm, and washable filling materials. Polyester staple fiber, with its lightweight, moisture-wicking, quick-drying, and durable properties, has replaced 70% of down in products such as sleeping bags, mattresses, sofas, and down apparel. The fiber's unique three-dimensional crimped structure traps a large amount of still air, effectively enhancing warmth. Currently, the market is further pursuing lightweight, high loft, and high warmth retention, placing higher standards on fiber compression resilience and multi-environment adaptability for warmth.

[0003] Downstream end-user brands continue to promote the upgrading of recycled material applications, and the filling field is gradually adopting recycled polyester (rPET) fibers comprehensively. Compared with virgin polyester raw materials, recycled fibers based on waste polyester bottle flakes and polyester films have both resource and cost advantages, which can significantly reduce raw material consumption and carbon emissions, and reduce overall production costs. However, recycled polyester raw materials from different sources will be repeatedly subjected to thermal processing and mechanical action during recycling, causing molecular chain breakage and degradation. Among them, the performance shortcomings of film-derived polyester raw materials are particularly prominent. The initial intrinsic viscosity is low, and the melt strength is insufficient during the spinning stage, which can easily lead to defects such as melt droplet breakage, capillary breakage, and fiber agglomeration. The fiber stability is far inferior to that of bottle flake-grade recycled polyester. The industry commonly uses the method of blending high-purity bottle flake raw materials with low-quality polyester films for modification. Although this can improve melt viscosity, it can easily cause significant differences in raw material batch performance, mismatch in heat shrinkage performance, and rapid decline in fiber bulkiness, making it difficult to guarantee the long-term warmth retention quality of recycled fibers.

[0004] Therefore, how to achieve stable spinning and forming capabilities of various types of recycled polyester materials without adding virgin polyester raw materials throughout the entire process, while endowing recycled fibers with comprehensive properties such as lightweight, high bulkiness, moisture resistance, and high-efficiency warmth retention, has become a key technical challenge that the development of the filled recycled polyester fiber industry urgently needs to overcome. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a multifunctional polyester staple fiber and its preparation method. Using recycled polyester from bottle flakes and membrane-derived recycled polyester as substrates, the fiber undergoes parallel composite spinning combined with hollow mesoporous silica microspheres and octyl polytrimethylsiloxane modification. The difference in thermal shrinkage between the two components forms a stable three-dimensional crimped structure, simultaneously endowing the fiber with high bulkiness, excellent compression resilience, high-efficiency warmth retention in both dry and wet states, and moisture resistance. This achieves stable spinning and functional upgrading of various types of recycled polyester materials.

[0006] The first objective of this invention is to provide a method for preparing multifunctional polyester staple fibers, comprising the following steps: S1. Mix recycled polyester flakes with hollow mesoporous silica microspheres to obtain component I; S2. Mix the membrane-derived recycled polyester with octyl polytrimethylsiloxane to obtain component II; S3. Composite spinning of component I in S1 and component II in S2 to obtain the multifunctional polyester staple fiber.

[0007] In one embodiment of the present invention, in S1, the intrinsic viscosity of the recycled bottle flake polyester is 0.7 dL / g-0.85 dL / g, and its chemical structure is polyethylene terephthalate. This intrinsic viscosity range ensures that the recycled bottle flake polyester and the membrane-source recycled polyester maintain a moderate difference in thermal shrinkage. When it is below 0.7 dL / g, the difference in shrinkage behavior between the two components is too small, which is not conducive to forming a stable three-dimensional crimped structure and will lead to a significant decrease in fiber bulkiness and warmth retention. When it is above 0.85 dL / g, the melt flowability is too poor, and the flow is mismatched with the low-viscosity membrane-source component in parallel composite spinning, which can easily cause spinning instability and fiber breakage problems. And / or, the particle size of the hollow mesoporous silica microspheres is 50nm-500nm; this particle size range can balance structural function, preparation feasibility and spinning stability. Within this range, the microspheres can maintain a regular hollow mesoporous morphology, give full play to heterogeneous nucleation and heat insulation effects, and can be stably prepared by conventional processes. They are uniformly dispersed in polyester melt, have low flow resistance, and do not affect the continuous forming of parallel composite spinning. When the particle size is less than 50nm, the hollow mesoporous structure is difficult to form stably, the industrial preparation yield is low, and the nanoparticles are prone to agglomeration and uneven dispersion. When the particle size is greater than 500nm, large particles are prone to causing spinneret blockage, capillary breakage and filament breakage problems in the melt.

[0008] In one embodiment of the present invention, in S1, the mass percentage of hollow mesoporous silica microspheres in component I is 0.5%-1.5%. Within this addition range, the hollow mesoporous structure can provide sufficient heterogeneous nucleation and insulation effects for the fiber, while ensuring uniform dispersion of the melt and guaranteeing continuous and stable parallel composite spinning. When the addition amount is less than 0.5%, there are insufficient heterogeneous nucleation sites, the crystallinity and rigidity of component I are limited, making it difficult to form a stable three-dimensional crimped skeleton, and the internal insulation air cavity is insufficient, which will cause a significant decrease in fiber compression resilience and heat retention performance. When the addition amount is greater than 1.5%, inorganic particles are prone to agglomeration in the melt, leading to deterioration of melt fluidity. The spinning process is prone to problems such as spinneret blockage, melt fracture and fiber breakage, while also increasing fiber brittleness and reducing softness.

[0009] In one embodiment of the present invention, in S2, the intrinsic viscosity of the membrane-source recycled polyester is 0.4 dL / g-0.55 dL / g, and its chemical structure is polyethylene terephthalate. Within this intrinsic viscosity range, it matches the actual degradation level of the recycled film material, allowing for stable spinning through modification with octyl polytrimethylsiloxane, while maintaining a significant difference in thermal shrinkage with the bottle flake component, ensuring stable formation of the fiber's three-dimensional crimp structure. When the intrinsic viscosity is below 0.4 dL / g, the molecular chains are too short, and even with the addition of octyl polytrimethylsiloxane for thickening, the melt strength still cannot meet the requirements for continuous spinning, easily leading to problems such as dripping, fiber breakage, and sliver shedding. When the intrinsic viscosity is above 0.55 dL / g, the viscosity difference with the bottle flake recycled polyester (intrinsic viscosity 0.7 dL / g-0.85 dL / g) narrows, resulting in insufficient difference in thermal shrinkage behavior between the two components, making it difficult to generate sufficient asymmetric shrinkage stress, and the three-dimensional crimp structure cannot be stably formed, thus leading to a decrease in fiber bulkiness and warmth retention.

[0010] In one embodiment of the present invention, in S2, the mass percentage of octyl polytrimethylsiloxane in component II is 1%-2.5%. This addition range can ensure that the membrane source component maintains low orientation and spinning continuity, and can also impart excellent wet hydrophobic and heat-retaining properties to the fiber through appropriate surface migration. When the addition amount is less than 1%, the physical entanglement between the long-chain siloxane molecules and the polyester is insufficient, making it difficult to effectively improve the melt strength. The spinning process is prone to droplet breakage. At the same time, the hindering effect on molecular chain orientation is insufficient, resulting in a reduction in the thermal shrinkage difference between the membrane source component and the bottle flake component. The three-dimensional crimped structure is difficult to form stably, and there are fewer hydrophobic groups that migrate to the fiber surface, resulting in a lower wet heat retention rate. When the addition amount is higher than 2.5%, the compatibility between the excessive siloxane and the polyester deteriorates, and it is easy to accumulate in the melt, causing spinneret blockage or fiber adhesion. Moreover, excessively hindering the movement of molecular chains will have an adverse effect on the mechanical properties of the fiber.

[0011] In one embodiment of the present invention, in S3, the mass ratio of component I to component II is (40-60):(40-60). This ratio allows the two components to form a moderate difference in thermal shrinkage and structural support during the parallel composite spinning process, taking into account the balanced performance of high fiber bulkiness, high resilience, and dry and wet heat insulation properties. If the proportion of component I is less than 40%, the high-shrinkage skeleton volume is insufficient, making it difficult to form a stable three-dimensional crimped structure, which will lead to a significant decrease in fiber bulkiness and heat insulation performance. If the proportion of component I is higher than 60%, the proportion of low-shrinkage component II is too small, which will not only make the wet hydrophobic heat insulation layer thinner, but also cause crimping collapse and deterioration of resilience due to excessive asymmetric shrinkage. At the same time, the excessively high proportion of high-viscosity melt will exacerbate the flow mismatch problem during the spinning process.

[0012] In one embodiment of the present invention, in S3, the specific steps of the composite spinning are as follows: first, the composite is melt-extruded by a screw, then melt-spun through a parallel composite spinning assembly, followed by pre-stretching, main stretching, relaxation heat setting, cooling and cutting.

[0013] In one embodiment of the present invention, during the melt extrusion process, the extrusion temperature of component I is 285°C-300°C, and the extrusion temperature of component II is 255°C-270°C. And / or, the melt spinning temperature is 270℃-290℃, the speed is 800m / min-1500m / min; side-blowing cooling is used, with component II facing the windward side and component I facing the leeward side, and the air temperature is 18℃-22℃; And / or, the pre-stretching temperature is 80℃-95℃, and the stretching ratio is 1.5 times-2.0 times; And / or, the temperature of the main draw is 90℃-105℃, and the draw ratio is 4-6 times; And / or, the relaxation heat setting temperature is 145℃-165℃, and the time is 10min-20min; And / or, the length of the cut fiber is 30mm-50mm.

[0014] In one embodiment of the present invention, side-blowing cooling is used during the melt spinning process, and the air temperature is controlled at 18°C-22°C, with component I facing the leeward side and component II facing the windward side.

[0015] A second objective of this invention is to provide a multifunctional polyester staple fiber prepared by the method described above.

[0016] In one embodiment of the present invention, the linear density of the multifunctional polyester staple fiber is 3dtex-10dtex, and the number of crimps is 12 / 25mm-20 / 25mm.

[0017] The technical solution of the present invention has the following advantages compared with the prior art: (1) The preparation method described in this invention utilizes the inherent difference in heat shrinkage properties between recycled polyester from two different sources, namely bottle flake recycled polyester and membrane source recycled polyester, and combines the two into monofilaments through parallel composite spinning. The high viscosity bottle flake recycled polyester shrinks more during subsequent heat treatment, while the low viscosity membrane source recycled polyester shrinks less, so that the fiber spontaneously forms a stable three-dimensional crimped structure that can store a large amount of still air, laying the foundation for the fiber's lightweight and excellent heat retention properties.

[0018] (2) The preparation method of the present invention adds hollow mesoporous silica microspheres to recycled polyester chips and processes them with a lower drawing temperature and a higher drawing ratio. The lower drawing temperature results in lower crystallinity and higher orientation in the drawing stage of this side, which reserves sufficient molecular chain shrinkage potential for subsequent high-temperature relaxation heat setting. The hollow mesoporous silica microspheres play a heterogeneous nucleation role in the relaxation heat setting stage, promote the rapid crystallization of molecular chains in the amorphous region, improve the modulus and rigidity of this side, and make it the inner skeleton of the three-dimensional coiled structure, giving the fiber excellent resistance to compression deformation and resilience.

[0019] (3) The preparation method of the present invention introduces octyl polytrimethylsiloxane into the membrane-source recycled polyester. Its long chain structure can form physical entanglement with the polyester molecular chain, significantly improving the melt strength to ensure a smooth and continuous spinning process. At the same time, the octyl polytrimethylsiloxane can hinder the orientation of the polyester molecular chain, so that the membrane-source recycled polyester component maintains a low degree of orientation, and thus exhibits less thermal shrinkage during high-temperature relaxation heat setting. In addition, during the heat treatment process, octyl polytrimethylsiloxane will migrate to the fiber surface, enhance the hydrophobicity of the outer side of the fiber, and improve the heat retention rate in a humid environment.

[0020] (4) The preparation method described in this invention adopts a side-blowing process in the spinning stage, so that the bottle-flake recycled polyester component faces the leeward side and the membrane-source recycled polyester component faces the windward side. The bottle-flake recycled polyester component on the leeward side cools down more slowly and the orientation degree is relatively improved. The membrane-source recycled polyester component on the windward side cools down faster and the orientation degree is further reduced, thereby increasing the potential shrinkage difference between the two components. After water bath pre-stretching, superheated steam main stretching and relaxation heat setting, the shrinkage difference is permanently fixed, forming a stable and uniform three-dimensional crimp, and finally a multifunctional recycled polyester short fiber with high bulkiness, excellent compression resilience and high-efficiency heat preservation performance in both dry and wet states is obtained. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0025] In this invention, unless otherwise stated, the recycled polyester used in the embodiments of this invention needs to be pre-crushed and ground to a powder size of 40 mesh before use.

[0026] In this invention, unless otherwise stated, the recycled polyester flakes used in the embodiments of this invention are purchased from Jiangsu Peipu Polymer Technology Co., Ltd., and the chemical structure is polyethylene terephthalate.

[0027] In this invention, unless otherwise stated, the membrane-source recycled polyester used in the embodiments of this invention was purchased from Yichang Shengteng New Materials Co., Ltd., and its chemical structure is polyethylene terephthalate.

[0028] In this invention, unless otherwise stated, the hollow mesoporous silica microspheres used in the embodiments of this invention were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd., with a particle size of 50nm-500nm.

[0029] In this invention, unless otherwise stated, the octyl polytrimethylsiloxane used in the embodiments of this invention was purchased from Nantong Zhonghe Chemical New Materials Co., Ltd. Example 1

[0030] The multifunctional polyester staple fiber and its preparation method in this embodiment specifically include the following steps: S1. Recycled polyester flakes with an intrinsic viscosity of 0.77 dL / g are mixed with hollow mesoporous silica microspheres to obtain component I; wherein, the mass percentage of hollow mesoporous silica microspheres in component I is 1.0%; S2. Mix the membrane-sourced recycled polyester with an intrinsic viscosity of 0.47 dL / g with octyl polytrimethylsiloxane to obtain component II; wherein, the mass percentage of octyl polytrimethylsiloxane in component II is 1.8%; S3. First, dry component I and component II separately until the moisture content is below 50 ppm. Then, feed them into the corresponding screws of the bicomponent composite spinning machine at a mass ratio of 50:50. The screw extrusion temperature of component I is 292℃, and the screw extrusion temperature of component II is 262℃. After the two components are melt-extruded by their respective screws, they are fed into the parallel composite spinning assembly for melt spinning at a temperature of 280℃ and a speed of 1150 m / min. Side-blowing cooling is used during the melt spinning stage, with a side-blowing temperature of 20℃. At the same time, the arrangement is adjusted so that component I is on the leeward side and component II is on the windward side. The nascent fibers obtained by melt spinning are bundled and then pre-stretched in an 87℃ water bath with a stretch ratio of 1.8 times. They are then mainly stretched under superheated steam at 97℃ with a stretch ratio of 5 times. Subsequently, they are relaxed and heat-set at 155℃ for 15 minutes to obtain a crimped structure. Finally, they are cooled and cut to a length of 40 mm to obtain multifunctional polyester staple fibers.

[0031] Example 2

[0032] The multifunctional polyester staple fiber and its preparation method in this embodiment specifically include the following steps: S1. Recycled polyester flakes with an intrinsic viscosity of 0.7 dL / g are mixed with hollow mesoporous silica microspheres to obtain component I; wherein, the mass percentage of hollow mesoporous silica microspheres in component I is 1.5%; S2. Mix the membrane-source recycled polyester with an intrinsic viscosity of 0.4 dL / g with octyl polytrimethylsiloxane to obtain component II; wherein, the mass percentage of octyl polytrimethylsiloxane in component II is 2.5%; S3. First, dry component I and component II separately until the moisture content is below 50 ppm. Then, feed them into the corresponding screws of the bicomponent composite spinning machine at a mass ratio of 40:60. The screw extrusion temperature of component I is 285℃, and the screw extrusion temperature of component II is 255℃. After the two components are melt-extruded by their respective screws, they are fed into the parallel composite spinning assembly for melt spinning at a temperature of 270℃ and a speed of 800 m / min. Side-blowing cooling is used during the melt spinning stage, with a side-blowing temperature of 18℃. At the same time, the arrangement is adjusted so that component I is on the leeward side and component II is on the windward side. The nascent fibers obtained by melt spinning are bundled and then pre-stretched in an 80℃ water bath with a stretch ratio of 1.5 times. Then, they are mainly stretched under 90℃ superheated steam with a stretch ratio of 4 times. Subsequently, they are relaxed and heat-set at 145℃ for 10 minutes to obtain a crimped structure. Finally, they are cooled and cut to a length of 30 mm to obtain multifunctional polyester staple fibers.

[0033] Example 3

[0034] The multifunctional polyester staple fiber and its preparation method in this embodiment specifically include the following steps: S1. Recycled polyester flakes with an intrinsic viscosity of 0.85 dL / g are mixed with hollow mesoporous silica microspheres to obtain component I; wherein, the mass percentage of hollow mesoporous silica microspheres in component I is 0.5%; S2. Mix the membrane-sourced recycled polyester with an intrinsic viscosity of 0.55 dL / g with octyl polytrimethylsiloxane to obtain component II; wherein, the mass percentage of octyl polytrimethylsiloxane in component II is 1%; S3. First, dry component I and component II separately until the moisture content is below 50 ppm. Then, feed them into the corresponding screws of the bicomponent composite spinning machine at a mass ratio of 60:40. The screw extrusion temperature of component I is 300℃, and the screw extrusion temperature of component II is 270℃. After the two components are melt-extruded by their respective screws, they are fed into the parallel composite spinning assembly for melt spinning at a temperature of 290℃ and a speed of 1500 m / min. Side-blowing cooling is used during the melt spinning stage, with a side-blowing temperature of 22℃. At the same time, the arrangement is adjusted so that component I is on the leeward side and component II is on the windward side. The nascent fibers obtained by melt spinning are bundled and then pre-stretched in a 95℃ water bath with a stretch ratio of 2.0 times. They are then mainly stretched under superheated steam at 105℃ with a stretch ratio of 6 times. Subsequently, they are relaxed and heat-set at 165℃ for 10 minutes to obtain a crimped structure. Finally, they are cooled and cut to a length of 50 mm to obtain multifunctional polyester staple fibers.

[0035] Comparative Example 1

[0036] The process is basically the same as in Example 1, except that the recycled polyester flakes with an intrinsic viscosity of 0.77 dL / g in S1 are replaced with recycled polyester from membrane sources with an intrinsic viscosity of 0.47 dL / g.

[0037] Comparative Example 2

[0038] The process is basically the same as in Example 1, except that the membrane-source recycled polyester with an intrinsic viscosity of 0.47 dL / g in S2 is replaced with bottle-flake recycled polyester with an intrinsic viscosity of 0.77 dL / g.

[0039] Comparative Example 3

[0040] The basic structure is the same as in Example 1, except that the hollow mesoporous silica microspheres in S1 are replaced with non-porous solid silica microspheres (purchased from Merck, catalog number 913898).

[0041] Comparative Example 4

[0042] The basic formula is the same as in Example 1, except that hollow mesoporous silica microspheres are not added in S1.

[0043] Comparative Example 5

[0044] The basic formula is the same as in Example 1, except that octyl polytrimethylsiloxane in S2 is replaced with polydimethylsiloxane (purchased from Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., with a molecular weight of 1000 g / mol).

[0045] Comparative Example 6

[0046] The process is basically the same as in Example 1, except that octyl polytrimethylsiloxane is not added in S2.

[0047] Test Example 1

[0048] Performance tests were conducted on the polyester staple fibers prepared in the examples and comparative examples: (1) Linear density: The test shall be conducted in accordance with Method A (weighing method of mid-section of bundle fiber) in GB / T 14335-2008 Test method for linear density of short chemical fiber; (2) Number of curls: Tested according to the standard of GB / T 14338-2022 Test method for the curl performance of chemical fiber short fiber; (3) Compression resilience: The compression resilience test shall be conducted in accordance with the standard in Appendix B of GB / T 35261-2017 tires; (4) Thermal insulation rate and heat transfer coefficient: The test shall be conducted in accordance with the standard GB / T 35762-2017 Test method for heat transfer properties of textiles, plate method; Table 1 shows the final measured parameters: Table 1

[0049] As can be seen from Table 1, the polyester staple fiber of the embodiment exhibits comprehensive advantages such as full crimp structure, excellent compression resilience, balanced dry and wet heat retention performance, and outstanding heat insulation effect. All key properties are significantly better than those of the comparative examples.

[0050] Comparing Example 1 and Comparative Example 1, it can be seen that the number of fiber crimps in Comparative Example 1 is significantly reduced, the compression resilience and heat retention performance are significantly worse, and the heat insulation effect is reduced. This is because both components are low-viscosity film-source recycled polyesters, which cannot form sufficient thermal shrinkage differences, making it difficult to construct a stable three-dimensional crimped structure. The fiber bulkiness is insufficient, and the static air storage capacity is greatly reduced.

[0051] Comparing Example 1 and Comparative Example 2, it can be seen that the three-dimensional crimping effect of the fibers in Comparative Example 2 is significantly weakened, the bulkiness is reduced, and the heat retention performance is worse. This is because both components are high-viscosity recycled polyester from bottle flakes, and their intrinsic viscosity and heat shrinkage behavior are very close, making it impossible to generate asymmetric shrinkage stress, making it difficult to form a crimped structure, and weakening the air-sealing ability.

[0052] Comparing Example 1 and Comparative Example 3, it can be seen that the fiber insulation performance of Comparative Example 3 is reduced, and the heat preservation effect in both dry and wet states is worse. This is because solid silica particles do not have a hollow mesoporous structure and cannot form heat-insulating air cavities inside the fiber. As a result, the scattering of heat radiation and the blocking effect of heat conduction are weak, and the overall heat preservation and insulation capacity is insufficient.

[0053] Comparing Example 1 and Comparative Example 4, it can be seen that the fiber crimp support of Comparative Example 4 is insufficient, the compression resilience is reduced, and the heat preservation and insulation performance is significantly reduced. This is because the heterogeneous nucleation effect of hollow mesoporous silica microspheres is lacking, the crystallization and rigidity of the bottle components are insufficient, and a stable crimped skeleton cannot be formed. At the same time, the internal air insulation structure is lacking, resulting in poor overall performance.

[0054] Comparing Example 1 and Comparative Example 5, it can be seen that the fiber crimping effect of Comparative Example 5 is worse, the compression resilience and heat retention performance are reduced, and the spinning stability is decreased. This is because the replaced siloxane side chain is shorter, the entanglement with polyester is weaker, and the obstacle to molecular chain orientation is insufficient. The shrinkage difference between the two components is smaller, and both fiber structure and function are affected.

[0055] Comparing Example 1 and Comparative Example 6, it can be seen that the fiber crimp structure of Comparative Example 6 is sparse, the bulkiness is insufficient, the wet heat retention rate is greatly reduced, and the heat insulation performance is worse. This is because the membrane source component lacks siloxane modification, the melt strength is insufficient and the orientation degree is too high, the shrinkage difference between the two components is greatly reduced, and the fiber surface has poor hydrophobicity, so moisture can easily damage the heat insulation structure.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing multifunctional polyester staple fiber, characterized in that, Includes the following steps: S1. Mix recycled polyester flakes with hollow mesoporous silica microspheres to obtain component I; the intrinsic viscosity of the recycled polyester flakes is 0.7 dL / g-0.85 dL / g; S2. Mix the membrane-derived recycled polyester with octyl polytrimethylsiloxane to obtain component II; the intrinsic viscosity of the membrane-derived recycled polyester is 0.4 dL / g-0.55 dL / g; S3. Composite spinning of component I in S1 and component II in S2 to obtain the multifunctional polyester staple fiber.

2. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S1, the chemical structure of the recycled polyester flakes is polyethylene terephthalate; And / or, the particle size of the hollow mesoporous silica microspheres is 50nm-500nm.

3. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S1, the mass percentage of hollow mesoporous silica microspheres in component I is 0.5%-1.5%.

4. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S2, the chemical structure of the membrane-sourced recycled polyester is polyethylene terephthalate.

5. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S2, the mass percentage of octyl polytrimethylsiloxane in component II is 1%-2.5%.

6. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S3, the mass ratio of component I to component II is (40-60):(40-60).

7. The method for preparing multifunctional polyester staple fiber according to claim 1, characterized in that, In S3, the specific steps of the composite spinning are as follows: first, the composite yarn is melt-extruded by a screw, then melt-spun through a parallel composite spinning assembly, followed by pre-stretching, main stretching, relaxation heat setting, cooling and cutting.

8. The method for preparing multifunctional polyester staple fiber according to claim 7, characterized in that, During the melt extrusion process, the extrusion temperature of component I is 285℃-300℃, and the extrusion temperature of component II is 255℃-270℃. And / or, the melt spinning temperature is 270℃-290℃, and the speed is 800m / min-1500m / min; And / or, the pre-stretching temperature is 80℃-95℃, and the stretching ratio is 1.5 times-2.0 times; And / or, the temperature of the main draw is 90℃-105℃, and the draw ratio is 4-6 times; And / or, the relaxation heat setting temperature is 145℃-165℃, and the time is 10min-20min; And / or, the length of the cut fiber is 30mm-50mm.

9. The method for preparing multifunctional polyester staple fiber according to claim 8, characterized in that, The melt spinning process employs side-blowing cooling, with the air temperature controlled at 18℃-22℃, and component I facing the leeward side and component II facing the windward side.

10. Multifunctional polyester staple fiber prepared by the method of any one of claims 1-9.

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