High-speed spinning ES fiber and preparation method thereof

Abstract

The invention relates to the technical field of fibers, and particularly discloses a high-speed spinning ES fiber and a preparation method thereof. The high-speed spinning ES fiber is prepared from the following raw materials in parts by weight: 40-60 parts of hexene copolymerized PE and 15-25 parts of a first compatilizer, and a core layer is prepared from the following raw materials in parts by weight: 35-45 parts of PEG modified PET, 15-25 parts of hyperbranched polyester modified PET and 10-20 parts of a second compatilizer. The crystallization kinetic performance of the skin layer and the core layer under the melt spinning condition is regulated and controlled through raw material design, so that the difference between the crystallization temperature and the crystallization rate of the skin-core two-component is remarkably reduced, the difference between the viscosity and the shrinkage rate is also effectively reduced, the asynchronous curing problem that the skin is tight and the core is loose under the high-speed spinning process is effectively solved, and the product quality is improved. Generation of huge shearing force at a skin-core interface is reduced, so that the fiber is not easy to break under higher-speed winding tension, and high-speed spinning is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fibers, more particularly, it relates to a high-speed spun ES fiber and a preparation method thereof. BACKGROUND

[0002] ES fiber is a typical sheath-core type double-component composite fiber, the sheath layer is usually high-density polyethylene (HDPE), and the core layer is usually polypropylene (PP) or polyethylene terephthalate (PET), which is widely used in the fields of sanitary products, medical materials and filter media due to its excellent thermal bonding, softness and strength.

[0003] At present, the production of traditional ES fiber usually adopts a two-step spinning process, the spinning speed is generally maintained at 1000-1600 m / min, and the fiber with a fiber fineness of 3 times the target fiber fineness (TOW) is first prepared through a pre-spinning process, and then the target fiber fineness product is obtained through a post-spinning process such as bundling, preheating drafting, steam setting, oiling, crimping, drying and cutting, etc. Due to the complicated post-processing procedure, long process, large equipment investment and low production efficiency, in recent years, a high-speed spinning process of ES fiber has been proposed, that is, by increasing the spinning speed, the fiber close to the target fiber fineness is directly obtained in the pre-spinning stage, and the post-spinning process is reduced or even eliminated.

[0004] However, for the related technology in the above, the inventors found that since the ES fiber is a double-component composite material, the crystallization temperature and crystallization rate of the double components are different, for example, the crystallization temperature of the core layer PP or PET is higher and the crystallization rate is slower, while the crystallization temperature of the sheath layer HDPE is lower and the crystallization rate is faster. In the rapid cooling process of high-speed spinning, the sheath layer PE may have been rapidly crystallized and solidified, while the core layer PP or PET is still in a molten or high-elastic state. This different step-by-step solidification state of "tight sheath and loose core" will generate a huge shear stress at the sheath-core interface, which will cause the fiber to easily break under the high-speed winding tension, making it difficult to realize high-speed spinning. In addition, the differences in viscosity, shrinkage rate and other physical properties between the double components further exacerbate the instability of the fiber in the high-speed forming process, which seriously restricts the realization of high-speed spinning of ES fiber. SUMMARY

[0005] In order to improve the compatibility between the double-component materials, improve the physical tensile properties of the fiber, reduce the high-speed spinning breakage phenomenon, and make the ES fiber applicable to the high-speed spinning process, the present application provides a high-speed spun ES fiber and a preparation method thereof.

[0006] In a first aspect, the present application provides a high-speed spun ES fiber, which adopts the following technical solution: A high-speed spun ES fiber, by weight, comprises 40-60 parts of hexene copolymer PE and 15-25 parts of a first compatibilizer in the sheath layer, and 35-45 parts of PEG-modified PET, 15-25 parts of hyperbranched polyester-modified PET and 10-20 parts of a second compatibilizer in the core layer.

[0007] In the above technical solution, hexene copolymer PE is introduced into the skin layer. Through the branching effect of α-olefin, the crystallinity and melting point of the skin layer PE are effectively reduced, the skin layer flexibility is increased, and the skin tightness problem during high-speed cooling is helped to alleviate the problem.

[0008] The core layer uses a synergistic system of PEG-modified PET and hyperbranched polyester-modified PET. The introduction of flexible segments of PEG disrupts the regularity of PET molecular chains, which significantly lowers the crystallization temperature of PET and reduces the difference between the crystallization temperature of PET and the sheath PE, thus reducing the difference in curing time between the sheath and the core. On the other hand, it enhances the mobility of PET molecular chains, accelerates the crystal growth rate, and improves the softness of the fiber.

[0009] The use of hyperbranched polyester modified PET has two advantages. First, its massive branched structure provides a large number of heterogeneous nucleation sites, significantly increasing the nucleation density of PET and overcoming the thermodynamic bottleneck of difficult PET nucleation. This allows the core layer to begin crystallization at higher temperatures. In synergy with PEG-modified PET, it accelerates the entire process of core layer PET from nucleation to growth. Second, the three-dimensional branched structure of hyperbranched polyester has a near-spherical molecular structure, which plays a role in the molecular ball effect in the melt. This further reduces the melt viscosity, improves fluidity, and effectively solves the viscosity fluctuation problem that may be caused by the introduction of PEG. This ensures that the core-sheath melt has a consistent flow rate in the spinning assembly, flows smoothly, and produces uniform yarn. It effectively avoids unstable phenomena such as melt breakage and fine stream oscillation caused by viscosity differences, meeting the "melt flow synchronization" requirement of high-speed spinning.

[0010] By adopting the above technical solution and through the synergistic design between the core layer raw material and the sheath layer raw material, the crystallization dynamics of the sheath and core layers are controlled separately, so that the sheath and core components are highly overlapped on the crystallization temperature and curing time axis, achieving a dynamic balance between the deceleration of the sheath layer and the acceleration of the core layer. This effectively reduces the problem of asynchronous curing when the sheath is tight and the core is loose, and reduces the generation of huge shear forces at the sheath-core interface. This makes the fiber less prone to breakage under high-speed winding tension, laying the foundation for high-speed spinning.

[0011] Optionally, the first compatibilizer is PE-g-MAH, and the second compatibilizer is ethylene-glyceryl methacrylate copolymer.

[0012] By adopting the above technical solution, the PE segments in PE-g-MAH are well compatible with the PE in the sheath layer, and the ethylene-glycerol methacrylate copolymer is compatible with the PET in the core layer. At the same time, its ethylene segments are well compatible with the PE in the sheath layer, thus becoming a molecular bridge connecting the sheath and core phases. Furthermore, under the high temperature conditions of melt spinning, the maleic anhydride groups in PE-g-MAH will attack the epoxy groups of the ethylene-glycerol methacrylate copolymer to undergo an epoxy ring-opening reaction and form covalent bonds. The covalent bonds form a chemical bridge at the sheath-core interface, constructing a tough interface layer. Compared with physical compatibilization that relies solely on van der Waals forces or hydrogen bonds, it can more effectively transfer and disperse the huge shear stress generated by high-speed spinning, reducing sheath-core interface peeling and fiber breakage caused by asynchronous sheath-core shrinkage.

[0013] Optionally, the hyperbranched polyester modified PET is an EO-PO block ether-based hyperbranched polyester, wherein the PO content is greater than the EO content.

[0014] Optionally, the preparation method of the hyperbranched polyester modified PET includes the following steps: Hydroxyl-terminated hyperbranched polyester was mixed with DMC catalyst, heated to 95-105℃, ethylene oxide was added and stirred to react, the temperature was further raised to 110-120℃, propylene oxide was added and stirred to react, the temperature was lowered and acetic acid was added for neutralization to obtain crude product, which was purified to obtain EO-PO block polyether hyperbranched polyester, which was then mixed with PET, vacuum dried and melt-blended extruded to obtain the final product. The mass fraction of EO-PO block polyether hyperbranched polyester in PET was 2.2-3.4%.

[0015] The above technical solution modifies HBP by grafting EO-PO blocks onto HBP terminal hydroxyl groups through ring-opening polymerization to obtain hyperbranched polyesters with EO-PO block ether groups. The EO segments can form weak hydrogen bonds with the polar groups of PET / PEG. This interaction is much weaker than the hydrogen bonds between hydroxyl groups and PET. It not only does not interfere with the crystallization of PET, but also adsorbs PEG by taking advantage of the homology between PO and PEG. This achieves the effect of both adsorbing and preventing the migration of PEG chain segments without restricting molecular movement, thus assisting the dispersion of PEG and avoiding the self-aggregation of PEG.

[0016] The block structure can adapt to both the core and sheath phases simultaneously. The hydrophobic segments of PO and the alkyl segments of PE form hydrophobic associations, which assist the transition of the core and sheath interface and form a transition layer to assist the transition of the core and sheath interface. This buffers the stress concentration during high-speed spinning and further reduces the breakage rate.

[0017] By adopting the above technical solution, the EO-PO block polyether hyperbranched polyester endows the hyperbranched polyester with the dual effects of nucleation and interface improvement. The higher PO segment content also ensures the incompatibility between the hyperbranched polyester and PET, and guarantees the promoting effect of the hyperbranched polyester on PET crystallization.

[0018] Optionally, the PEG used in the PEG-modified PET has a molecular weight of 1000-2000.

[0019] By adopting the above technical solution, the inventors discovered that, under the same addition amount, PEG 1000-2000 can more effectively reduce the glass transition temperature, accelerate PET crystal growth, and, in synergy with the molecular ball effect of hyperbranched polyester, make the viscosity of the core melt stable and its fluidity excellent. This ensures the uniformity and stability of high-speed spinning through the micro-spinnerets, effectively reduces spinning pressure, reduces fiber breakage, and at the same time endows ES fibers with optimal mechanical properties.

[0020] Optionally, the method for preparing the PEG-modified PET includes the following steps: The product is obtained by adding 4.2-5.7% PEG and 0.8-1.2% coupling agent by mass to PET and then performing melt extrusion.

[0021] Secondly, this application provides a method for preparing high-speed spun ES fibers, employing the following technical solution: A method for preparing high-speed spun ES fibers includes the following steps: Hexene copolymer PE and a first compatibilizer are mixed to obtain a skin layer material, and PEG-modified PET, hyperbranched polyester-modified PET and a second compatibilizer are mixed to obtain a core layer material. The sheath material and the core material are fed into different spinning systems, melted separately, and extruded through the sheath-core spinning assembly. When exiting the spinneret, they are composite spun to form ES fibers with a sheath-core structure. After winding, bundling, stretching, heat setting, crimping, and cutting, the final product is obtained.

[0022] Optionally, the mass ratio of the skin material to the core material is (1-1.2):1.

[0023] By adopting the above technical solution, ES fiber has better flow matching and can maintain fiber stability under the condition of huge shear stress at the core-sheath interface, making it less prone to breakage and enabling high-speed spinning. Compared with the traditional process that involves complicated post-spinning steps and investment, this application obtains fibers close to the target fineness in the pre-spinning stage. The operation process is simpler and easier to operate, making it suitable for industrial production.

[0024] In summary, this application has the following beneficial effects: 1. This application uses ethylene copolymer PE as the sheath material and PEG-modified PET and hyperbranched polyester-modified PET composite as the core material. The crystallization kinetics of the sheath and core layers under melt spinning conditions are controlled respectively, which significantly reduces the difference between the crystallization temperature and crystallization rate of the sheath and core components, and also effectively reduces the difference between viscosity and shrinkage rate. This effectively improves the asynchronous solidification problem of tight sheath and loose core under high-speed spinning process, reduces the generation of huge shear force at the sheath-core interface, and makes the fiber less prone to breakage under higher speed winding tension.

[0025] 2. In this application, EO-PO block ether-based hyperbranched polyester is preferred to modify PET. The EO-PO amphiphilic block structure is compatible with both the core and sheath phases. On the one hand, it can prevent PEG segment migration and avoid PEG self-aggregation. On the other hand, it can form an interface layer to assist the transition of the core and sheath interface, buffer the stress concentration generated during high-speed spinning, and further reduce the fiber breakage rate.

[0026] 3. Compared with traditional processes that involve complicated post-spinning steps and investments, this application achieves high-speed spinning, obtaining fibers with near-target fineness in the pre-spinning stage. The operation process is simpler and easier to operate, making it suitable for industrial production. Detailed Implementation

[0027] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0028] raw material Unless otherwise specified, all raw materials used in the embodiments and comparative examples in this application are commercially available products, specifically: Hydroxyl-terminated hyperbranched polyester, selected from Wuhan Hyperbranched Resin Technology Co., Ltd., H2O3; The DMC catalyst was selected from Jiangsu Bader Polyurethane Co., Ltd., and is a Zn-Co type catalyst. PET, sourced from Qinghua Plastics Factory in Jizhou District, Hengshui City, with product number PET-QH and grade Qh-pet; Coupling agent, selected from BASF, ADR 4468; The preparation of hexene copolymer PE was carried out with reference to invention patent CN109535532B. In the Unipol polyethylene process unit, ethylene, hydrogen and 1-hexene were used as raw materials, and Ziegler-Natta Ti-based catalyst was used to carry out the reaction in a gas phase fluidized bed reactor. The product hexene copolymer PE had a 1-hexene content of 2.1% and a melt flow index of 54.8 g / 10 min. HDPE, sourced from Fushun Petrochemical, 2911; Ethylene-glyceryl methacrylate copolymer, selected from SK, South Korea. AX8840; PE-g-MAH, selected from Dongguan Xingyuan Chemical Co., Ltd., S-2100 Examples of preparation of hyperbranched polyester-modified PET: 1.1-1.4 Preparation Example 1.1 The preparation method of hyperbranched polyester modified PET includes the following steps: S1: Mix 100g of hydroxyl-terminated hyperbranched polyester with 0.35g of DMC catalyst and add it to the reactor. Turn on the stirring and heating. Add 72g of ethylene oxide under nitrogen atmosphere and 95℃, and stir to react for 2h. S2: Heat the reactor to 110°C, add 145g of propylene oxide, stir and react for 3 hours, cool the reactor to below 60°C, slowly add 1g of acetic acid into the reactor, stir for 30 minutes to neutralize the DMC catalyst, terminate the reaction, and obtain the crude product. S3: Pour the crude product into 500 mL of anhydrous ethanol, stir for 1 h, filter, wash three times with anhydrous ethanol to remove unreacted monomers and acetate impurities, and then dry under vacuum to obtain EO-PO block polyether hyperbranched polyester. S4: Add 2.2% by mass of EO-PO block polyether hyperbranched polyester and 0.15% by mass of NaH2PO4 to PET, and then melt-blend and extrude after vacuum drying to obtain the product.

[0029] Preparation Example 1.2 The preparation method of hyperbranched polyester modified PET includes the following steps: S1: Mix 100g of hydroxyl-terminated hyperbranched polyester with 0.35g of DMC catalyst and add it to the reactor. Start stirring and heating. Add 72g of ethylene oxide under nitrogen atmosphere and 100℃, and stir to react for 1.5h. S2: Heat the reactor to 115℃, add 145g of propylene oxide, stir and react for 2.5h, cool the reactor to below 60℃, slowly add 1g of acetic acid into the reactor, stir for 30min to neutralize the DMC catalyst, terminate the reaction, and obtain the crude product. S3: Pour the crude product into 500 mL of anhydrous ethanol, stir for 1 h, filter, wash three times with anhydrous ethanol to remove unreacted monomers and acetate impurities, and then dry under vacuum to obtain EO-PO block polyether hyperbranched polyester. S4: Add 2.9% by mass of EO-PO block polyether hyperbranched polyester and 0.15% by mass of NaH2PO4 to PET, and then melt-blend and extrude after vacuum drying to obtain the product.

[0030] Preparation Example 1.3 The preparation method of hyperbranched polyester modified PET includes the following steps: S1: Mix 100g of hydroxyl-terminated hyperbranched polyester with 0.35g of DMC catalyst and add it to the reactor. Turn on the stirring and heating. Add 72g of ethylene oxide under nitrogen atmosphere and 105℃, and stir to react for 1h. S2: Heat the reactor to 120°C, add 145g of propylene oxide, stir and react for 2 hours, cool the reactor to below 60°C, slowly add 1g of acetic acid into the reactor, stir for 30 minutes to neutralize the DMC catalyst, terminate the reaction, and obtain the crude product. S3: Pour the crude product into 500 mL of anhydrous ethanol, stir for 1 h, filter, wash three times with anhydrous ethanol to remove unreacted monomers and acetate impurities, and then dry under vacuum to obtain EO-PO block polyether hyperbranched polyester. S4: Add 3.4% by mass of EO-PO block polyether hyperbranched polyester and 0.15% by mass of NaH2PO4 to PET, and then melt-blend and extrude after vacuum drying to obtain the product.

[0031] Preparation Example 1.4 The preparation method of hyperbranched polyester modified PET includes the following steps: adding 2.2% by mass of terminal hydroxyl hyperbranched polyester and 0.15% by mass of NaH2PO4 to PET, followed by vacuum drying and melt blending extrusion to obtain the PET.

[0032] Examples of PEG-modified PET preparation 2.1-2.5 Preparation Example 2.1 The preparation method of PEG-modified PET includes the following steps: Add 5.7% PEG-1000 and 1.2% coupling agent by mass to PET, and perform chain extension in a twin-screw extruder at a chain extension temperature of 260℃ and a rotation speed of 300r / min to obtain the final product.

[0033] Preparation Example 2.2 The preparation method of PEG-modified PET includes the following steps: Add 5.1% PEG-1500 and 1% coupling agent by mass to PET, and perform chain extension in a twin-screw extruder at a chain extension temperature of 260℃ and a rotation speed of 300r / min to obtain the final product.

[0034] Preparation Example 2.3 The preparation method of PEG-modified PET includes the following steps: The product is obtained by adding 4.2% PEG-2000 and 0.8% coupling agent by mass to PET, performing chain extension in a twin-screw extruder at a chain extension temperature of 260℃ and a rotation speed of 300r / min.

[0035] Preparation Example 2.4 The PEG-modified PET differs from Preparation Example 2.1 in that PEG-1000 is replaced with an equal amount of PEG-3000, while all other steps are the same as in Preparation Example 2.1.

[0036] Preparation Example 2.5 The PEG-modified PET differs from Preparation Example 2.1 in that PEG-1000 is replaced with an equal amount of PEG-600, while all other steps are the same as in Preparation Example 2.1. Example

[0037] Example 1 A high-speed spun ES fiber comprises a sheath and a core layer. By weight, the sheath material comprises 40 parts of hexene copolymer PE and 25 parts of PE-g-MAH, and the core material comprises 35 parts of PEG-modified PET prepared in Preparation Example 2.1, 20 parts of hyperbranched polyester-modified PET prepared in Preparation Example 1.1, and 15 parts of ethylene-glycerol methacrylate copolymer. The above-mentioned method for preparing high-speed spun ES fibers includes the following steps: S1: Mix hexene copolymer PE and PE-g-MAH to obtain the skin material, and mix PEG modified PET, hyperbranched polyester modified PET and ethylene-glyceryl methacrylate copolymer to obtain the core material; S2: The sheath material and core material are fed into different spinning systems at a mass ratio of 1:1. After melting, they are extruded through the sheath-core spinning assembly and composite spinning is performed at the exit of the spinneret to form ES fibers with a sheath-core structure. After winding, bundling, stretching, heat setting, crimping and cutting, the desired fiber is obtained. The spinning speed is 4100 m / min, the side blowing temperature is 20℃, the air humidity is 75%, the side blowing speed is 0.9 m / min, the stretching ratio is 1.3, and the heat setting temperature is 105℃.

[0038] Example 2 A high-speed spun ES fiber comprises a sheath and a core layer. By weight, the sheath material comprises 50 parts of hexene copolymer PE and 20 parts of PE-g-MAH, and the core material comprises 45 parts of PEG-modified PET prepared in Preparation Example 2.2, 25 parts of hyperbranched polyester-modified PET prepared in Preparation Example 1.2, and 10 parts of ethylene-glycerol methacrylate copolymer. The above-mentioned method for preparing high-speed spun ES fibers includes the following steps: S1: Mix hexene copolymer PE and PE-g-MAH to obtain the skin material, and mix PEG modified PET, hyperbranched polyester modified PET and ethylene-glyceryl methacrylate copolymer to obtain the core material; S2: The sheath material and core material are fed into different spinning systems at a mass ratio of 1.1:1. After melting, they are extruded through the sheath-core spinning assembly and composite spinning is performed at the exit of the spinneret to form ES fibers with a sheath-core structure. After winding, bundling, stretching, heat setting, crimping and cutting, the desired fiber is obtained. The spinning speed is 4000m / min, the side blowing temperature is 20℃, the air humidity is 75%, the side blowing speed is 0.9m / min, the stretching ratio is 1.3, and the heat setting temperature is 105℃.

[0039] Example 3 A high-speed spun ES fiber comprises a sheath and a core layer. By weight, the sheath material comprises 60 parts of hexene copolymer PE and 15 parts of PE-g-MAH, and the core material comprises 40 parts of PEG-modified PET prepared in Preparation Example 2.3, 15 parts of hyperbranched polyester-modified PET prepared in Preparation Example 1.3, and 20 parts of ethylene-glycerol methacrylate copolymer. The above-mentioned method for preparing high-speed spun ES fibers includes the following steps: S1: Mix hexene copolymer PE and PE-g-MAH to obtain the skin material, and mix PEG modified PET, hyperbranched polyester modified PET and ethylene-glyceryl methacrylate copolymer to obtain the core material; S2: The sheath material and core material are fed into different spinning systems at a mass ratio of 1.2:1. After melting, they are extruded through the sheath-core spinning assembly and composite spinning is performed at the exit of the spinneret to form ES fibers with a sheath-core structure. After winding, bundling, stretching, heat setting, crimping and cutting, the desired fiber is obtained. The spinning speed is 3500m / min, the side blowing temperature is 20℃, the air humidity is 75%, the side blowing speed is 0.9m / min, the stretching ratio is 1.3, and the heat setting temperature is 105℃.

[0040] Example 4 A high-speed spun ES fiber differs from Example 1 in that the hyperbranched polyester-modified PET in the core layer raw material is prepared by Preparation Example 1.4, while the other steps are the same as in Example 1.

[0041] Example 5 A high-speed spun ES fiber, which differs from Example 1 in that the PEG-modified PET in the core layer raw material is prepared by Preparation Example 2.4, while the other steps are the same as in Example 1.

[0042] Example 6 A high-speed spun ES fiber, which differs from Example 1 in that the PEG-modified PET in the core layer raw material is prepared by Preparation Example 2.5, while the other steps are the same as in Example 1.

[0043] Comparative Example 1 A high-speed spun ES fiber differs from Example 1 in that the hexene copolymer PE in the sheath material is replaced with an equal mass of HDPE, while the other steps are the same as in Example 1.

[0044] Comparative Example 2 A high-speed spun ES fiber differs from Example 1 in that the PEG-modified PET prepared in Preparation Example 2.1 in the core layer raw material is replaced with an equal mass of hyperbranched polyester-modified PET prepared in Preparation Example 1.1, while all other steps are the same as in Example 1.

[0045] Comparative Example 3 A high-speed spun ES fiber differs from Example 1 in that the hyperbranched polyester-modified PET prepared in Preparation Example 1.1 is replaced with an equal mass of PEG-modified PET prepared in Preparation Example 2.1 in the core layer raw material, while all other steps are the same as in Example 1.

[0046] Performance testing The highest spinning speeds of the high-speed spun ES fibers prepared in Examples 1-6 and Comparative Examples 1-3 without problems such as fiber breakage, fuzz, and structural defects during continuous and stable spinning were recorded in Table 1. At the same time, the spinning phenomenon of ES fibers was observed. The fineness, breaking strength, breaking elongation and wicking height of the high-speed spun ES fibers prepared in Examples 1-6 and Comparative Examples 1-3 were tested according to the relevant methods specified in GB / T 14335-2022, GB / T 14337-2022 and GB / T 21655.1-2008, respectively. Each group of tests was performed 3 times, and the average value of the 3 test results was recorded as the final result in Table 1.

[0047] Table 1 As can be seen from the performance test results in Table 1, this application improves the sheath and core materials of the bicomponent ES fiber by using ethylene copolymer PE as the sheath material and PEG-modified PET and hyperbranched polyester-modified PET composite as the core material. This controls the crystallization kinetics of the sheath and core under melt spinning conditions, significantly reducing the difference in crystallization temperature and crystallization rate between the sheath and core components. At the same time, it effectively reduces the differences in physical properties such as viscosity and shrinkage between the two components, enabling the ES fiber to reach a maximum spinning speed of 4100 m / min without breaking the filament.

[0048] In Comparative Example 1, the sheath crystallized too quickly, resulting in poor sheath-core synchronization and a significant decrease in spinning speed and performance. In Comparative Example 2, the lack of plasticizing and crystallization-accelerating effects of PEG-modified PET resulted in slow core crystallization growth, decreased spinning speed, and reduced hydrophilicity. In Comparative Example 3, the lack of anisotropic nucleation and interface improvement effects of hyperbranched polyester-modified PET made core crystallization difficult, leading to a decrease in spinning speed and a significant decrease in the performance of ES fibers.

[0049] In Example 4, PET was modified with hydroxyl-terminated hyperbranched polyester. It can be seen that the maximum spinning speed of the fiber decreased significantly. This is because the hydrogen bonding between the hydroxyl-terminated hyperbranched polyester and PET inhibits the crystallization rate of PET, and cannot achieve the effect of regulating and shortening the crystallization temperature and crystallization rate of the two components. However, when PET was modified by grafting EO-PO blocks onto the hydroxyl-terminated HBP to obtain EO-PO block ether groups, the highly polar hydroxyl-terminated hydroxyl groups were transformed into large, compliant ether chains composed of long-chain propylene oxide and ethylene oxide. Although hydroxyl groups are still present, they are difficult to form strong hydrogen bonds with PET molecular segments. The introduction of PO segments also changed the nature of the interaction between the hyperbranched polyester and the PET matrix, ensuring the incompatibility between the hyperbranched polyester and PET. This allows the amphiphilic EO-PO block polyether hyperbranched polyester-modified PET to simultaneously adapt to both the core and sheath phases, achieving the dual effects of heterogeneous nucleation and core-sheath interface improvement.

[0050] According to the performance test results of Examples 1 and 5-6, the ES fibers prepared by PEG-modified PET with a molecular weight of 1000-2000 have the best performance. If the molecular weight is too large, the speed-up effect is poor, and the synergistic effect between the PET and the hyperbranched polyester modified with EO-PO block ether groups decreases, resulting in a decrease in both spinning speed and performance. If the molecular weight is too small, the performance of the ES fibers may be reduced due to molecular migration.

[0051] 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 high speed spun ES fiber comprising a sheath and core bicomponent characterized in that, The skin layer material comprises 40-60 parts of hexene copolymer PE and 15-25 parts of the first compatibilizer by weight, and the core layer material comprises 35-45 parts of PEG modified PET, 15-25 parts of hyperbranched polyester modified PET and 10-20 parts of the second compatibilizer.

2. The high-speed spun ES fiber according to claim 1, characterized in that, The first compatibilizer is PE-g-MAH, and the second compatibilizer is ethylene-glyceryl methacrylate copolymer.

3. The high-speed spun ES fiber according to claim 1, characterized in that, The hyperbranched polyester modified PET adopts an end EO-PO block ether-based hyperbranched polyester, wherein the PO content is greater than the EO content.

4. The high-speed spun ES fiber according to claim 3, characterized in that, The preparation method of the hyperbranched polyester modified PET comprises the following steps: The end hydroxyl hyperbranched polyester is mixed with a DMC catalyst, heated to 95-105 DEG C, and then stirred and reacted after adding ethylene oxide. The temperature is continuously increased to 110-120 DEG C, and then stirred and reacted after adding propylene oxide. After cooling, acetic acid is added for neutralization to obtain a crude product. The end EO-PO block polyether hyperbranched polyester is obtained after purification. The end EO-PO block polyether hyperbranched polyester is mixed with PET, vacuum dried, melt blended and extruded to obtain the end EO-PO block polyether hyperbranched polyester, and the mass fraction of the end EO-PO block polyether hyperbranched polyester in the PET is 2.2-3.4%.

5. The high-speed spun ES fiber according to claim 1, wherein The PEG used in the PEG modified PET has a molecular weight of 1000-2000.

6. The high-speed spun ES fiber according to claim 5, characterized in that The preparation method of the PEG modified PET comprises the following steps: adding PEG with a mass fraction of 4.2-5.7% and 0.8-1.2% coupling agent to PET, and then melt extruding to obtain the PEG modified PET.

7. The process for the production of high-speed spun ES fibres according to any one of claims 1 to 6, characterised in that, The preparation method comprises the following steps: The hexene copolymer PE and the first compatibilizer are mixed to obtain the skin layer material, and the PEG modified PET, the hyperbranched polyester modified PET and the second compatibilizer are mixed to obtain the core layer material. The skin layer material and the core layer material are respectively fed into different spinning systems, respectively melt-extruded through a skin-core spinning assembly, and then composite spun to form ES fibers with a skin-core structure when the spinning holes are discharged. After winding, bundling, stretching, heat setting, crimping and cutting, the ES fibers are obtained.

8. The process for the preparation of high-speed spun ES fibres according to claim 7, characterised in that, The mass ratio of the skin layer material to the core layer material is (1-1.2):1.

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