Poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane with high mechanical properties, preparation method and application thereof

Abstract

The application discloses a poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane with high mechanical performance and a preparation method and application thereof. The poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane is prepared by physical blending of poly(4-methyl-1-pentene) and polypropylene and a thermal phase separation method using a green mixed diluent. Under the action of strong van der Waals force between chain segments, the molecular chains are intertwined, and the large pores and small pores are uniformly distributed in the main body structure of the membrane, so that the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane has higher mechanical performance and rigidity, the tensile strength of the membrane is greater than or equal to 10 MPa, the breaking stress is greater than or equal to 150 cN, and the breaking elongation is greater than or equal to 500%, which fully meets the mechanical performance requirements of the hollow fiber oxygenation membrane and the mechanical performance requirements of the oxygenation membrane wire for weaving. Meanwhile, the membrane still has an asymmetric structure, has a dense skin layer, and has a blood plasma leakage time of at least 7 days, and can meet the use requirements of long-time blood oxygenation.

Description

Technical Field

[0001] This invention relates to the field of membrane technology, specifically to a high-mechanical-performance poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane, its preparation method, and its application in artificial lungs.

[0002] Background Area

[0003] Extracorporeal membrane oxygenation (ECMO, also known as artificial lung) is mainly used to provide continuous extracorporeal respiration and circulation for patients with severe cardiopulmonary failure. Its working principle is that venous blood with low oxygen content enters the membrane oxygenator through a centrifugal pump, and gas exchange occurs between the oxygenation membrane and the air-oxygen mixture. The oxygen concentration in the blood increases and the carbon dioxide concentration decreases, becoming highly oxygenated blood, which is then returned to the body.

[0004] Polypropylene (PP) is a representative material of second-generation microporous hollow fiber oxygenation membranes. PP oxygenation membranes have high porosity, high gas exchange efficiency, and also possess high mechanical strength and excellent rigidity. However, due to the presence of surface micropores, plasma leakage is prone to occur during oxygenation, thus limiting its application to short-term oxygenation and significantly restricting its range of applications.

[0005] Poly(4-methyl-1-pentene) (PMP) is a representative material of third-generation solid hollow fiber oxygen membranes. PMP oxygen membranes have high thermal stability (melting point 220-240℃) and low surface tension (24 mMm). -1 With good biocompatibility and high gas permeability, PMP membranes have become the mainstream membrane oxygenator material in recent years. PMP membranes combine a microporous main structure that facilitates gas permeation with a dense, ultra-high-density epidermal layer that comes into direct contact with blood. Therefore, they possess both highly efficient gas exchange capabilities and effectively solve the problem of plasma leakage from PP membranes, allowing for continuous use for several weeks and greatly expanding their application scenarios and fields.

[0006] Currently, hollow fiber oxygenation membranes are mainly prepared using a thermally induced phase separation method. The resulting hollow fiber membrane fibers need to be woven and assembled before they can be used for blood oxygenation. However, almost all PMP oxygenators in China are currently imported. One important reason is that PMP membrane fibers have low mechanical strength, are soft and easily deformed, requiring highly advanced weaving techniques, making the weaving of PMP membrane fibers extremely difficult. In contrast, PP hollow fiber membranes have higher mechanical strength and excellent rigidity, making them less prone to flattening and breakage during weaving. Therefore, domestic weaving technology can be used to produce PP membrane oxygenators.

[0007] In view of the above, to promote the localization of PMP oxygenators, PMP can be modified in the material field to give the PMP membrane fibers both high mechanical properties and the characteristic of high resistance to plasma leakage. This would allow for the simultaneous realization of membrane fiber weaving, oxygenator production, and long-term blood oxygenation. How to integrate the advantages of high mechanical properties and rigidity of PP membranes with the high resistance to plasma leakage of PMP membranes is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] In the first aspect of this invention, since poly(4-methyl-1-pentene) (PMP) is a semi-crystalline nonpolar polyolefin resin, its large side-chain structure results in a rather loose packing, with an overall polymer density of approximately 0.830 g / cm³, the lowest among all thermoplastic resins. Therefore, PMP films exhibit poor mechanical properties, weak rigidity, and are prone to deformation. Polypropylene, on the other hand, possesses superior mechanical properties and excellent rigidity. Blending it with PMP can effectively improve the mechanical properties and rigidity of the PMP film, solving problems such as flattening, breakage, and deformation that may occur during the weaving process.

[0009] In another aspect of this invention, directly blending poly(4-methyl-1-pentene) and polypropylene results in significant phase separation between PP as dispersed spherulites and PMP. Therefore, this invention abandons traditional phthalate diluents, which are toxic and harmful to humans, and instead uses a more environmentally friendly green mixed diluent to regulate the membrane structure. This allows for the alternating and uniform distribution of 100-700 nm pores and 1 μm-4 μm macropores within the membrane matrix, maintaining a high gas exchange rate. Simultaneously, the membrane retains an asymmetric structure with a dense skin layer providing high resistance to plasma leakage, meeting the requirements for long-term blood oxygenation.

[0010] The technical solution of the present invention is as follows:

[0011] The present invention relates to a high mechanical property poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane; the hollow fiber alloy membrane is composed of poly(4-methyl-1-pentene) and polypropylene, exhibiting small pores of 100-700 nm and large pores of 1 μm-4 μm that appear alternately and are uniformly distributed in the membrane body, while the membrane still has an asymmetric structure.

[0012] The method for preparing the high-mechanical-performance poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane of the present invention adopts a one-step method and includes the following steps:

[0013] 1): Mix poly(4-methyl-1-pentene), polypropylene and green mixed diluent evenly, stir and melt the blend at 230-260℃ to form a homogeneous casting solution, and let it stand to remove bubbles;

[0014] 2): The casting liquid in step 1) is extruded through a spinneret to form a film, and then enters a cooling bath to separate the solid and liquid or liquid-liquid phases and solidify into a film. Then, the film is wound and collected by a winding wheel to obtain the hollow fiber alloy film precursor.

[0015] 3): Immerse the hollow fiber alloy membrane precursor obtained in step 2) in the extractant to fully extract the diluent in the membrane;

[0016] 4): Place the membrane obtained from the extraction in step 3) in a vacuum oven to dry it. The result is a poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane.

[0017] In step 1), 100 parts by weight of poly-4-methyl-1-pentene and 0.5-30 parts by weight of polypropylene are used; the sum of the mass components of poly-4-methyl-1-pentene and polypropylene in the blend is 20% to 40%.

[0018] The green mixed diluent includes at least two of acetylacetonate trioctyl citrate (ATOC), acetylacetonate tributyl citrate (ATBC), and tributyl citrate (TBC).

[0019] In step 1), the blend is melted at 230–260°C for 6–12 hours to form a homogeneous blend, and then allowed to stand for 8–14 hours to degas.

[0020] In step 2), the molten homogeneous blend is extruded through a spinneret to form a hollow fiber film. The extrusion speed of the liquid is 5-50 ml / min, and the core liquid flow rate is 10-100 ml / min. Then, it enters a cooling bath at 5-60°C to undergo solid-liquid or liquid-liquid phase separation and solidify into a film. The cooling bath includes one of water, trioctyl acetyl citrate, tributyl acetyl citrate, tributyl citrate, and anhydrous ethanol. Subsequently, the fibers are wound and taken up by a winding wheel at a winding speed of 0.5-1.5 m / s.

[0021] In step 3), the obtained hollow fiber alloy membrane precursor is immersed in an extractant for 12 to 96 hours; the extractant includes anhydrous ethanol and / or isopropanol.

[0022] In step 4), the extracted membrane is placed in an oven to dry at a temperature of 40–60°C for 6–12 hours.

[0023] The poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane of the present invention has high mechanical properties, with tensile strength ≥10MPa, breaking stress ≥150cN, and elongation at break ≥500%.

[0024] The application of the high mechanical properties of the poly-4-methyl-1-pentene / polypropylene hollow fiber alloy membrane of the present invention in the manufacture of artificial lungs.

[0025] This invention utilizes a blend of poly(4-methyl-1-pentene) and polypropylene. Polypropylene, acting as a reinforcing phase for poly(4-methyl-1-pentene), exhibits superior mechanical properties and excellent rigidity. Both poly(4-methyl-1-pentene) and polypropylene have a full carbon chain structure; under the strong van der Waals forces between chain segments, the molecular chains intertwine, enhancing the mechanical properties and rigidity of the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane. The poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane provided by this invention has a tensile strength ≥10 MPa, a breaking stress ≥150 cN, and an elongation at break ≥500%, fully meeting the mechanical performance requirements of hollow fiber oxygen membranes (breaking stress ≥60 cN, elongation at break ≥60%), and significantly exceeding the upper limit of the tensile strength of ECMO PMP oxygen membrane filaments (6.5 MPa), thus fully meeting the mechanical performance requirements of braided oxygen membrane filaments.

[0026] The preparation method of the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane provided by this invention is simple and easy to control. Polypropylene is introduced into poly(4-methyl-1-pentene) through physical blending. By controlling the use of a green mixed diluent, the pore structure of the hollow fiber alloy membrane can be optimized, resulting in a staggered and uniformly distributed structure within the membrane matrix, maintaining a high gas exchange rate. Simultaneously, the membrane retains an asymmetric structure with a dense skin layer providing high resistance to plasma leakage, with a plasma leakage time of at least 7 days, meeting the requirements for long-term blood oxygenation. Attached Figure Description

[0027] Figure 1 These are SEM images (overall view and cross-sectional structure) of the hollow fiber membrane prepared in Example 1.

[0028] Figure 2 These are SEM images (overall view and cross-sectional structure) of the hollow fiber membrane prepared in Example 2.

[0029] Figure 3 This is a SEM image (structural view near the outer edge of the cross-section) of the hollow fiber membrane prepared in Example 1.

[0030] Figure 4 This is a SEM image (structural view near the outer edge of the cross-section) of the hollow fiber membrane prepared in Example 2. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below, but the following embodiments are by no means intended to limit the present invention.

[0032] Example 1

[0033] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0034] Step 1: Take 200g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 200:1) and 800g of the mixed diluent (trioctyl acetyl citrate to tributyl acetyl citrate in a mass ratio of 10:1), add them to the feed vessel, melt the mixture at 250℃ for 8 hours until a homogeneous casting solution is formed, and let it stand for 12 hours to remove bubbles.

[0035] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret to form a film. The extrusion speed is 15 ml / min, the core liquid flow rate is 30 ml / min, the winding wheel speed is 0.89 m / s, the cooling bath temperature is 10℃, and the cooling medium is water.

[0036] Step 3: Immerse the membrane obtained in Step 2 in anhydrous ethanol for 24 hours to allow for complete extraction. Then, dry the membrane in a 40°C oven for 12 hours.

[0037] Figure 1 These are scanning electron microscope (SEM) images of the cross-sections of the poly(4-methyl-1-pentene) hollow fiber alloy membrane product in Example 1 of this invention, at magnifications of 150x and 5000x. Figure 1 It can be seen that macropores of 1-2 μm and micropores of 100-700 nm appear alternately in the membrane structure and are evenly distributed.

[0038] Example 2

[0039] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0040] Step 1: Take 250g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 4:1) and 750g of the mixed diluent (trioctyl acetyl citrate to tributyl acetyl citrate in a mass ratio of 2:5), add them to the feed vessel, melt the mixture at 240℃ for 6 hours to form a homogeneous casting solution, and let it stand for 14 hours to remove bubbles.

[0041] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret at an extrusion speed of 10 ml / min, a core liquid flow rate of 40 ml / min, a winding wheel speed of 1.12 m / s, a cooling bath temperature of 5°C, and a cooling medium of trioctyl acetyl citrate. Step 3: The membrane obtained in Step 2 is immersed in isopropanol for 96 hours to allow for complete extraction. The membrane is then dried in a 55°C oven for 10 hours.

[0042] Figure 2 These are scanning electron microscope (SEM) images of the cross-sections of the poly(4-methyl-1-pentene) hollow fiber alloy membrane product in Example 2 of this invention, at magnifications of 150x and 5000x. Figure 2It can be seen that macropores of 2-4 μm and micropores of 100-700 nm appear alternately in the membrane structure and are evenly distributed.

[0043] Example 3

[0044] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0045] Step 1: Take 400g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 9:1) and 600g of the mixed diluent (trioctyl acetyl citrate to tributyl citrate in a mass ratio of 2:1), add them to the feed vessel, melt the mixture at 260℃ for 10h until a homogeneous casting solution is formed, and let it stand for 10h to remove bubbles.

[0046] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret to form a film. The extrusion speed is 5 ml / min, the core liquid flow rate is 10 ml / min, the winding wheel speed is 0.5 m / s, the cooling bath temperature is 20℃, and the cooling medium is tributyl acetylacetate.

[0047] Step 3: Immerse the membrane obtained in Step 2 in anhydrous ethanol for 36 hours to allow for complete extraction. Then, dry the membrane in a 50°C oven for 6 hours.

[0048] Example 4

[0049] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0050] Step 1: Take 350g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 10:3) and 650g of the mixed diluent (acetylacetic acid dibutyl ester to tributyl citrate in a mass ratio of 1:10), add them to the feed vessel, melt the mixture at 230℃ for 12h until a homogeneous casting solution is formed, and let it stand for 10h to remove bubbles.

[0051] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret to form a film. The extrusion speed is 50 ml / min, the core liquid flow rate is 80 ml / min, the winding wheel speed is 0.89 m / s, the cooling bath temperature is 60℃, and the cooling medium is tributyl citrate.

[0052] Step 3: Immerse the membrane obtained in Step 2 in isopropanol for 48 hours to allow for complete extraction. Then, dry the membrane in a 60°C oven for 8 hours.

[0053] Example 5

[0054] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0055] Step 1: Take 300g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 10:1) and 700g of the mixed diluent (acetylacetic acid dibutyl ester to tributyl citrate in a mass ratio of 1:3), add them to the feed vessel, melt the mixture at 240℃ for 10h until a homogeneous casting solution is formed, and let it stand for 8h to remove bubbles.

[0056] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret to form a film. The extrusion speed is 40 ml / min, the core liquid flow rate is 100 ml / min, the winding wheel speed is 1.35 m / s, the cooling bath temperature is 50℃, and the cooling medium is anhydrous ethanol.

[0057] Step 3: Immerse the membrane obtained in Step 2 in anhydrous ethanol for 12 hours to allow for complete extraction. Then, dry the membrane in a 40°C oven for 10 hours.

[0058] Example 6

[0059] A poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane was prepared using the following steps:

[0060] Step 1: Take 250g of the mixture (poly(4-methyl-1-pentene) to polypropylene in a mass ratio of 5:1) and 750g of the mixed diluent (acetylacetonate dioctyl citrate, acetylacetonate dibutyl citrate and tributyl citrate in a mass ratio of 4:6:1) and add them to the feed vessel. Melt the mixture at 250℃ for 12 hours to form a homogeneous casting solution, and let it stand for 8 hours to remove bubbles.

[0061] Step 2: The homogeneous casting solution described in Step 1 is extruded through a spinneret to form a film. The extrusion speed is 35 ml / min, the core liquid flow rate is 70 ml / min, the winding wheel speed is 1.5 m / s, the cooling bath temperature is 40℃, and the cooling medium is dibutyl acetylacetate.

[0062] Step 3: Immerse the membrane obtained in Step 2 in isopropanol for 72 hours to allow for complete extraction. Then, dry the membrane in a 45°C oven for 6 hours.

[0063] The structure and properties of the hollow fiber membrane products (membrane products) obtained in Examples 1-6 of this invention were characterized by the following test methods:

[0064] I. Scanning electron microscope image

[0065] High-resolution emission scanning electron microscopy (SEM) was used to observe a cross-section of the membrane product. The membrane product was cut into short strips, immersed in liquid nitrogen, and quenched to obtain the cross-section. The membrane product was then fixed on a sample stage, plated with platinum (Pt), and observed using SEM. SEM images of the cross-section at 150x, 5000x, and 20000x magnification were obtained. The 5000x magnification image shows the central portion of the membrane wall cross-section, and the 20000x magnification image shows the outer edge of the membrane wall cross-section.

[0066] II. Determination of Tensile Strength and Elongation at Break

[0067] Using a universal testing machine, the membrane product was stretched at a constant speed of 2 mm / min at room temperature until it broke, and the tensile strength and elongation at break of the membrane product were obtained.

[0068] III. Determination of Gas Permeation Flux

[0069] At room temperature, the membrane product is encapsulated into a module. A gas source is connected to one side of the membrane product and a pressure of 0.1 to 1 bar is applied. A soap membrane flow meter is connected to the other side of the membrane product to obtain the gas flux of the membrane module. Based on the effective area of ​​the membrane product, the gas permeation flux can be calculated.

[0070] IV. Determination of resistance to plasma leakage

[0071] The membrane product was sealed into a membrane module, and a phospholipid solution (1.5g L-α-lecithin dissolved in 500ml physiological saline) was introduced into the upstream side of the membrane module at a rate of 6L / min·m. 2 The membrane circulates at a constant speed, and nitrogen gas is introduced downstream to purge along the other surface of the membrane. The purge gas outlet leads to a drying tube containing anhydrous copper sulfate. The time it takes for the anhydrous copper sulfate in the drying tube to begin to change color is observed, which is the plasma leakage time.

[0072] The results of the various performance tests are shown in the following tables:

[0073] Table 1

[0074]

[0075] As can be seen from the performance of the membrane products in Examples 1-6 in Table 1, the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane has excellent mechanical properties. The tensile strength of Examples 1-6 is above 10 MPa and the breaking stress is above 150 cN. This indicates that the addition of polypropylene improves the mechanical properties of the poly(4-methyl-1-pentene) membrane.

[0076] Figure 3This is a scanning electron microscope (SEM) image of the cross-section of the poly(4-methyl-1-pentene) hollow fiber alloy membrane product in Example 1 of this invention, magnified at 20,000x. Figure 4 This is a scanning electron microscope (SEM) image of the cross-section of the poly(4-methyl-1-pentene) hollow fiber alloy membrane product in Example 2 of this invention, magnified 20,000 times. According to... Figure 3 and Figure 4 It is evident that the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane of the present invention possesses a distinct dense skin layer. This indicates that the addition of polypropylene did not affect the formation of the dense skin layer, and the membrane product still exhibits excellent resistance to plasma leakage. According to the plasma leakage resistance test results, the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane has a plasma leakage resistance time of at least 7 days, which fully meets the requirements for long-term blood oxygenation.

[0077] In summary, the poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane provided by this invention not only possesses excellent mechanical properties but also high gas permeability. The hollow fiber alloy membrane is prepared in a one-step process by blending mechanically superior polypropylene with poly(4-methyl-1-pentene). The rigid segments of polypropylene and the segments of poly(4-methyl-1-pentene) are intertwined by strong van der Waals forces, achieving molecular-level mixing and forming a polymer alloy structure, which significantly improves the mechanical properties of the hollow fiber membrane. By using a green mixed diluent to regulate the membrane structure, some of the original small pores in the membrane matrix are replaced by large pores, resulting in a pore structure with alternating and uniformly distributed large and small pores, exhibiting high gas permeability. Furthermore, the membrane surface is smooth and dense, exhibiting good resistance to plasma leakage, making it suitable for use in membrane oxygenators and extracorporeal membrane oxygenation (ECMO).

[0078] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0079] [References]

[0080] [1]X.Huang,W.Wang,Z.Zheng,X.Wang,J.Shi,W.Fan,L.Li,Z.Zhang,Dissipativeparticle dynamics study and experimental verification on the poremorphologies and diffusivity of the poly(4-methyl-1-pentene)-diluent systemvia thermally induced phase separation:the effect of diluent and polymerconcentration,Journal of membranescience.514(2016)487–500.

[0081] [2]Kessler E,Batzilla T,Wechs F.Integrally asymmetrical polyolefinmembrane:US,6497752-B1[P].2002-12-24.

[0082] [3]Tang Y H,Li M F,Lin Y K,et al.A novel green diluent for thepreparation of poly(4-methyl-1-pentene)membranes via a thermally-inducedphase separation method[J].Membranes,2021,11(8):1-17.

[0083] [4]Mueller M O,Kessler E,Hornscheidt R R.Integrally asemmetricalpolyolefinmembrane for gas exchange:US,6409921-B1[P].2002-06-25.

[0084] [5]Tao H J,Zhang J,Wang X L,et al.Phase separation and polymercrystallization in apoly(4-methyl-1-pentene)-dioctylsebacate-dimethylphthalate system via thermally induced phase separation[J].Journal ofPolymer Science Part B-Polymer Physics,2007,45(2):153-161。

Claims

1. A high-mechanical-performance poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane; characterized in that, The hollow fiber alloy membrane is composed of poly(4-methyl-1-pentene) and polypropylene. It exhibits small pores of 100-700 nm and large pores of 1 μm-4 μm that appear alternately and are evenly distributed in the membrane body. At the same time, the membrane still has an asymmetric structure. The hollow fiber alloy membrane is prepared by a one-step method, including the following steps: 1): Mix poly(4-methyl-1-pentene), polypropylene and green mixed diluent evenly, stir and melt the blend at 230~260℃ to form a homogeneous casting solution, and let it stand to remove bubbles; 2): The homogeneous casting liquid in step 1) is extruded through a spinneret to form a film, and then enters a cooling bath to separate the solid and liquid or liquid-liquid phases and solidify into a film. Then, the film is wound and taken up by a winding wheel to obtain the hollow fiber alloy film precursor. 3): Immerse the hollow fiber alloy membrane precursor obtained in step 2) in the extractant to fully extract the diluent in the membrane; 4): The membrane obtained from the extraction in step 3) is dried in a vacuum oven, and the result is a poly(4-methyl-1-pentene) / polypropylene hollow fiber alloy membrane. 100 parts by weight of poly(4-methyl-1-pentene) and 0.5-30 parts by weight of polypropylene; the sum of the mass components of poly(4-methyl-1-pentene) and polypropylene in the blend is 20%-40%. The green mixed diluent includes at least two of acetylated trioctyl citrate (ATOC), acetylated tributyl citrate (ATBC), and tributyl citrate (TBC); Step 1) The blend is melted at 230~260℃ for 6~12h to form a homogeneous casting solution, and then allowed to stand for 8~14h to remove bubbles; In step 2), the molten homogeneous casting solution is extruded through a spinneret to form a hollow fiber film. The extrusion speed of the solution is 5-50 mL / min, and the core liquid flow rate is 10-100 mL / min. Then, it enters a cooling bath at 5-60°C to solidify into a film through solid-liquid or liquid-liquid phase separation. The cooling bath includes one of water, trioctyl acetyl citrate, tributyl acetyl citrate, tributyl citrate, and anhydrous ethanol. Subsequently, the film is wound and taken up by a winding wheel at a winding speed of 0.5-1.5 m / s. In step 3), the obtained hollow fiber alloy membrane precursor is immersed in an extractant for 12-96 hours; the extractant includes anhydrous ethanol and / or isopropanol. In step 4), the extracted membrane is placed in a vacuum oven to dry at a temperature of 40-60°C for 6-12 hours.

2. The application of the high mechanical properties poly-4-methyl-1-pentene / polypropylene hollow fiber alloy membrane as described in claim 1 in the manufacture of artificial lungs.

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