A fluorine surface-modified hollow fiber membrane material and a method for preparing the same

Abstract

This invention provides a fluorine-modified hollow fiber membrane material, its preparation method, and its applications. Specifically, the fluorine-modified hollow fiber membrane is prepared by the following steps: Step 1, preparing a casting solution containing polyolefin material and a diluent; Step 2, preparing a hollow fiber membrane precursor from the casting solution using a spinning process; Step 3, sequentially passing the hollow fiber membrane precursor through an air gap, a cooling tank, and a solvent exchange tank to obtain a semi-finished membrane after removing the diluent; the cooling liquid in the cooling tank is perfluoropolyether or dihydroxy perfluoropolyether; Step 4, drying the semi-finished membrane to obtain a fluorine-modified hollow fiber membrane. This invention utilizes the cooling process during spinning to simultaneously cool the hollow fiber membrane at a relatively high speed while performing fluorine modification and forming fluorine-containing chemical functional groups, effectively improving the biocompatibility of the hollow fiber membrane.

Description

Technical Field

[0001] This invention relates to the field of material surface modification technology, and more specifically, to a fluorine-modified hollow fiber membrane material and its preparation method. Background Technology

[0002] A membrane oxygenator, also known as a membrane artificial lung, is a disposable artificial device that enables blood gas exchange. It is primarily used for extracorporeal circulation support during critical care or disease treatment and is a core component of current extracorporeal membrane oxygenation (ECMO) equipment, mechanical perfusion equipment, and donor organ mechanical perfusion protection equipment. During system operation, the patient's blood flows outside a hollow fiber membrane, while oxygen is injected into the membrane. Carbon dioxide in the blood and oxygen in the membrane fibers are exchanged through pressure difference to achieve the gas exchange function of the lungs. This requires the membrane material to have both excellent air permeability and long-term hydrophobicity to meet the requirements of continuous operation for weeks or even months in clinical settings. Therefore, the most critical component of a membrane oxygenator is the hollow fiber membrane material; the performance of the membrane material determines the performance of the oxygenator. In addition, since the membrane material comes into direct contact with the blood, the membrane material used must also have excellent blood compatibility.

[0003] EP2295132A1 proposes a preparation strategy for antithrombotic extracorporeal blood circuits and their components, including hollow fiber membranes, blood tubes, and filters, as well as their applications in hemofiltration, hemodialysis, hemodiafiltration, blood concentration, and blood oxygenation, which can avoid the use of anticoagulants. The hollow fiber membrane defined in this document incorporates fluorinated macromolecules through a blending process. To achieve the effect of reducing thrombus formation, a large amount of these fluorinated macromolecules must be used. CN113316481A proposes a dialyzer using fluorinated hollow fiber membranes. The hollow fiber membrane defined in this document incorporates fluorinated macromolecules through a blending process. To achieve a certain degree of improved biocompatibility, a large amount of fluorinated macromolecules is also required. However, for the thermal spinning process of hollow fiber membranes, the method of improving membrane biocompatibility by blending a large amount of fluorinated macromolecules into the casting solution can easily affect the membrane forming process, leading to membrane degradation and hindering continuous membrane production. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to propose an improved hollow fiber membrane preparation technology by adjusting the cooling process, so as to make full use of the coolant in the hollow fiber membrane preparation process to obtain a fluorine-modified hollow fiber membrane.

[0005] The purpose of this invention is to improve the process of preparing hollow fiber membranes by using a coolant. Fluorine is added to the surface of the hollow fiber membrane under the action of a fluorine-containing coolant, thereby forming fluorine-containing chemical groups on the surface of the fiber membrane.

[0006] The first aspect of this invention provides a method for preparing a fluorine-modified hollow fiber membrane, the method comprising the following steps:

[0007] Step 1: Prepare a casting solution containing polyolefin material and diluent;

[0008] Step 2: The casting solution is used to prepare hollow fiber membrane precursors through a spinning process;

[0009] Step 3: Pass the hollow fiber membrane precursor through an air gap, a cooling tank, and a solvent exchange tank in sequence to obtain a semi-finished membrane after removing the diluent; the coolant in the cooling tank is at least one of perfluoropolyether and dihydroxy perfluoropolyether.

[0010] Step 4: Dry the semi-finished membrane to obtain a fluorine-modified hollow fiber membrane.

[0011] Furthermore, the polyolefin material content in the casting solution is 20wt% to 50wt%, and the diluent content is 50wt% to 80wt%.

[0012] Furthermore, the polyolefin material is selected from poly4-methyl-1-pentene and polypropylene.

[0013] Furthermore, the diluent is selected from at least one of dioctyl oxalate, glyceryl triacetate, dibutyl phthalate, and dioctyl phthalate.

[0014] Further, in step 2, the spinning process involves extruding the casting solution through a spinneret to form hollow fibers. The difference between the outer diameter and the inner diameter of the spinneret is 5 μm to 500 μm. Preferably, the difference between the outer diameter and the inner diameter of the spinneret is 150 μm to 500 μm.

[0015] Further, the inner diameter of the spinneret is 50μm to 500μm, and the outer diameter of the spinneret is 100μm to 1000μm. Preferably, the inner diameter of the spinneret is 100μm to 300μm, and the outer diameter of the spinneret is 200μm to 800μm.

[0016] Further, the gas in the air gap is at least one selected from air, nitrogen, and carbon dioxide, and the air gap is 10 mm to 500 mm. Preferably, the air gap is 50 mm to 300 mm.

[0017] Furthermore, the extrusion spinning speed is 20 m / min to 300 m / min. Preferably, the extrusion spinning speed is 20 m / min to 100 m / min.

[0018] Furthermore, the temperature of the coolant in the cooling pool is 25°C to 65°C. Preferably, the temperature of the coolant in the cooling pool is 30°C to 60°C.

[0019] Further, in step 3, the solvent exchange tank is provided with an extractant to remove the diluent through extraction; the extractant is selected from at least one of ethanol, isopropanol, N,N-dimethylformamide, ethyl acetate, amyl acetate, dichloromethane, and ethylene glycol butyl ether; the extraction time in the solvent exchange tank is 10h to 100h.

[0020] Furthermore, in step 4, the drying method is oven drying, vacuum drying, or natural drying at normal pressure and temperature. The drying temperature is 40℃~200℃, and the drying time is 10h~50h.

[0021] A second aspect of the present invention provides a fluorine-modified hollow fiber membrane obtained by the above preparation method.

[0022] A third aspect of the present invention provides the use of the fluorine-modified hollow fiber membrane, wherein the fluorine-modified hollow fiber membrane is used as a medium for blood gas exchange during extracorporeal membrane oxygenation.

[0023] Beneficial effects

[0024] This invention modifies hollow fiber membranes directly during the cooling process by designing the coolant, thereby forming fluorine-containing chemical groups in the hollow fiber membrane and improving the biocompatibility of the fiber membrane.

[0025] Compared with the prior art, the present invention makes full use of the key role of the cooling process in the spinning process. By designing and screening the cooling liquid, the hollow fiber membrane is cooled at a relatively fast speed, while the hollow fiber membrane is fluorinated and fluorine-containing chemical functional groups are formed, which effectively improves the biocompatibility of the hollow fiber membrane. Attached Figure Description

[0026] Figure 1 Electron microscope images of fiber membranes obtained using conventional methods.

[0027] Figure 2 Electron microscope images of fiber membranes obtained using the method of this invention.

[0028] Figure 3 The image shows the infrared spectrum of the fiber membrane obtained using the conventional method in Comparative Example 1.

[0029] Figure 4 The infrared spectrum of the fiber membrane obtained using the method of this invention is shown.

[0030] Figure 5 The infrared spectrum of the fiber membrane obtained using Comparative Example 2 is shown. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention. The technical solution of the present invention does not limit the device for the cooling liquid, because those skilled in the art, given the conditions of hollow fiber membrane spinning and forming, can design devices such as cooling pools according to specific experimental needs.

[0032] Some specific embodiments provide a method for preparing a fluorine-modified hollow fiber membrane, the method comprising the following steps:

[0033] Step 1: Prepare a casting solution containing polyolefin material and diluent;

[0034] In some specific embodiments, the content of polyolefin material in the casting solution is 20 wt% to 50 wt%, and the content of diluent is 50 wt% to 80 wt%; the sum of the contents of polyolefin material and diluent is 100%; for example, the content of polyolefin material is 20 wt%, and the content of diluent is 80 wt%; the content of polyolefin material is 30 wt%, and the content of diluent is 70 wt%; the content of polyolefin material is 40 wt%, and the content of diluent is 60 wt%; the content of polyolefin material is 50 wt%, and the content of diluent is 50 wt%. The polyolefin material is selected from poly(4-methyl-1-pentene) and polypropylene; the diluent is selected from at least one of dioctyl oxalate, glyceryl triacetate, dibutyl phthalate, and dioctyl phthalate.

[0035] In some specific embodiments, the casting solution is obtained by melting, stirring, and degassing polyolefin materials and diluents in a twin-screw extruder.

[0036] Step 2: The casting solution is used to prepare hollow fiber membrane precursors through a spinning process;

[0037] In some specific implementations, in step 2, the spinning process involves extruding the casting solution through a spinneret to form hollow fibers. The difference between the outer diameter and the inner diameter of the spinneret is 150 μm to 500 μm, for example, 200 μm, 300 μm, or 400 μm. The inner diameter of the spinneret is 100 μm to 300 μm, for example, 200 μm; the outer diameter of the spinneret is 200 μm to 800 μm, for example, 200 μm, 300 μm, or 400 μm. The extrusion spinning speed is 80 m / min to 200 m / min, for example, 30 m / min, 40 m / min, 50 m / min, 60 m / min, or 70 m / min.

[0038] Step 3: Pass the hollow fiber membrane precursor through an air gap, a cooling tank, and a solvent exchange tank in sequence to obtain a semi-finished membrane after removing the diluent; the coolant in the cooling tank is at least one of perfluoropolyether and dihydroxy perfluoropolyether.

[0039] In some specific embodiments, the gas in the air gap is at least one selected from air, nitrogen, and carbon dioxide, and the gap itself is 50 mm to 300 mm, for example, 100 mm or 200 mm.

[0040] In some specific implementations, the temperature of the coolant in the cooling pool is 30°C to 60°C.

[0041] In some specific implementations, in step 3, the solvent exchange tank is equipped with an extractant to remove the diluent through extraction. The extractant is selected from at least one of ethanol, isopropanol, N,N-dimethylformamide, ethyl acetate, amyl acetate, dichloromethane, and ethylene glycol butyl ether. The extraction time in the solvent exchange tank is 10h to 100h, for example, 20h, 30h, 40h, 50h, 60h, 70h, 80h, or 90h.

[0042] Step 4: Dry the semi-finished membrane to obtain a fluorine-modified hollow fiber membrane;

[0043] In some specific implementation schemes, in step 4, the drying method is oven drying, vacuum drying, or natural drying at normal pressure and temperature. The drying temperature is 40℃~200℃, for example, 50℃, 100℃, or 150℃; the drying time is 10h~50h, for example, 20h, 30h, or 40h.

[0044] The fluorine-modified hollow fiber membrane provided by this invention can be used as a medium for blood gas exchange during extracorporeal membrane oxygenation (ECMO).

[0045] Example 1: Preparation of Fluorine-Surface Modified Hollow Fiber Membranes

[0046] Step 1: Melt, stir, and degas the raw material containing 30% poly4-methyl-1-pentene and 70% dibutyl phthalate in a twin-screw extruder to obtain a casting solution;

[0047] Step 2: The casting solution is ejected through a spinneret with an inner diameter of 100 μm and an outer diameter of 500 μm, and the spinning speed is 35 m / min to obtain the hollow fiber membrane precursor.

[0048] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling tank to cool it, and extract it in an exchange tank for 12 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap has a space of 100 mm, the gas in the air gap is air, the coolant in the cooling tank is perfluoropolyether at 30°C, and the extractant in the exchange tank is ethanol solvent.

[0049] Step 4: Dry the semi-finished membrane at 80℃ for 12 hours to obtain a fluorine-modified hollow fiber membrane.

[0050] Example 2: Preparation of Fluorine-Surface Modified Hollow Fiber Membranes

[0051] Step 1: Melt, stir, and degas the raw material containing 30% poly4-methyl-1-pentene and 70% triacetylglycerol in a twin-screw extruder to obtain a casting solution;

[0052] Step 2: The casting solution is ejected through a spinneret with an inner diameter of 200 μm and an outer diameter of 600 μm, and the spinning speed is 120 m / min to obtain the hollow fiber membrane precursor.

[0053] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling pool to cool it, and extract it in an exchange pool for 16 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap has a space of 200 mm, the gas in the air gap is air, the coolant in the cooling pool is 40℃ dihydroxy perfluoropolyether, and the extractant in the exchange pool is isopropanol solvent.

[0054] Step 4: Dry the semi-finished membrane at 100℃ for 10 hours to obtain a fluorine-modified hollow fiber membrane.

[0055] Example 3: Preparation of Fluorine-Surface Modified Hollow Fiber Membranes

[0056] Step 1: Melt, stir, and degas the raw material containing 40% poly-4-methyl-1-pentene and 60% dioctyl phthalate in a twin-screw extruder to obtain a casting solution;

[0057] Step 2: The casting solution is ejected through a spinneret with an inner diameter of 300 μm and an outer diameter of 800 μm, and the spinning speed is 40 m / min to obtain the hollow fiber membrane precursor.

[0058] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling tank to cool it, and then extract it in an exchange tank for 20 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap has a space of 300 mm, the gas in the air gap is air, the coolant in the cooling tank is 50℃ dihydroxy perfluoropolyether, and the extractant in the exchange tank is ethyl acetate.

[0059] Step 4: Dry the semi-finished membrane at 150°C for 16 hours to obtain a fluorine-modified hollow fiber membrane.

[0060] Example 4: Preparation of Fluorine Surface-Modified Hollow Fiber Membranes

[0061] Step 1: Melt, stir, and degas the raw material containing 40% poly-4-methyl-1-pentene and 60% triacetylglycerol in a twin-screw extruder to obtain a casting solution;

[0062] Step 2: The casting solution is ejected through a spinneret with an inner diameter of 200 μm and an outer diameter of 600 μm, and the spinning speed is 40 m / min to obtain the hollow fiber membrane precursor.

[0063] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling tank to cool it, and extract it in an exchange tank for 20 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap has a space of 200 mm, the gas in the air gap is air, the coolant in the cooling tank is 40℃ dihydroxy perfluoropolyether, and the extractant in the exchange tank is dichloromethane.

[0064] Step 4: Dry the semi-finished membrane at 100℃ for 10 hours to obtain a fluorine-modified hollow fiber membrane.

[0065] Example 5: Preparation of Fluorine-Surface Modified Hollow Fiber Membranes

[0066] Step 1: Melt, stir, and degas the raw material containing 30% polypropylene and 70% dioctyl oxalate in a twin-screw extruder to obtain a casting solution;

[0067] Step 2: The casting solution is ejected through a spinneret with an inner diameter of 50 μm and an outer diameter of 200 μm, and the spinning speed is 40 m / min to obtain the hollow fiber membrane precursor.

[0068] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling tank to cool it, and extract it in an exchange tank for 24 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap is 50 mm, the gas in the air gap is nitrogen, the coolant in the cooling tank is 60°C perfluoropolyether, and the extractant in the exchange tank is N,N-dimethylformamide.

[0069] Step 4: Dry the semi-finished membrane at 70°C for 48 hours to obtain a fluorine-modified hollow fiber membrane.

[0070] Comparative Example 1: Preparation of Conventional Hollow Fiber Membranes

[0071] The same method as in Example 1 was used, except that the coolant in the cooling pool was replaced with water.

[0072] Comparative Example 2: Preparation of Fluorine-Modified Hollow Fiber Membranes

[0073] Step 1: Melt, stir, and degas the raw material containing 40% poly4-methyl-1-pentene and 60% dibutyl phthalate in a twin-screw extruder to obtain a casting solution;

[0074] Step 2: Spin the casting solution through a spinneret with an inner diameter of 100 μm and an outer diameter of 500 μm, and spin at a speed of 100 m / min to obtain a hollow fiber membrane precursor.

[0075] Step 3: Pass the hollow fiber membrane precursor through an air gap, immerse it in a cooling pool to cool it, and extract it in an exchange pool for 12 hours to obtain a semi-finished membrane after removing the diluent; wherein, the air gap is 100 mm, the cooling liquid in the cooling pool is water at 30°C, and the extractant in the exchange pool is ethanol solvent.

[0076] Step 4: Dry the semi-finished membrane at 80°C for 12 hours to obtain a hollow fiber membrane;

[0077] Step 5: Soak the hollow fiber membrane in perfluoropolyether for 30 minutes, then remove and dry it.

[0078] Test results

[0079] First, the surface and cross-section of the hollow fiber were observed using a scanning electron microscope. Figure 1 The image shown is a scanning electron microscope image of the poly(4-methyl-1-pentene) hollow fiber membrane obtained using conventional water cooling liquid in Comparative Example 1. It can be seen that the outer skin of the hollow fiber membrane is smooth and flat, while the cross-section shows a distinctly rough morphology.

[0080] Scanning electron microscope images of the hollow fiber membrane obtained in Example 1 are shown below. Figure 2 As shown, compared with conventional processes, the method of the present invention does not affect the dense morphological structure of the outer skin layer, thus ensuring the mechanical properties and permeability of the membrane fibers.

[0081] Furthermore, the chemical structure of the hollow fiber membrane surface was analyzed using infrared spectroscopy, and the results are as follows: Figure 3-5 As shown in the figure, compared with hollow fiber membranes obtained by conventional processes, the hollow fiber membranes obtained by this method retain the original characteristic peaks, confirming the retention of the main components of the hollow fiber membrane. Furthermore, the hollow fiber membranes prepared by this method exhibit peaks at 1026 cm⁻¹. -1 and 1058cm -1 The presence of a distinct fluorine-containing characteristic peak at 1663 cm⁻¹ confirms the formation of fluorine-containing chemical groups. Furthermore, the hollow fiber membrane prepared by this method exhibits a peak at 1663 cm⁻¹. -1The presence of characteristic peaks caused by the stretching motion of carboxylic acids and carbonyl groups is typical of fluoride degradation. When acetal units in fluorides come into contact with moisture in the air, they are hydrolyzed into carbonyl groups, which further confirms the generation of fluorine-containing chemical groups.

[0082] Furthermore, the hollow fiber membranes obtained in Example 1 and Comparative Example 2 were compared using infrared spectroscopy. Figure 4 (As shown). A comparison reveals that the hollow fiber membrane prepared by the method of the present invention in Example 1 exhibits strong characteristic peaks of CF and carbonyl groups, indicating that the method of the present invention can effectively modify the surface of the hollow fiber membrane. However, the hollow fiber membrane obtained in Comparative Example 2 only shows characteristic peaks of CF and lacks carbonyl group peaks. These results demonstrate that the present method yields a fluorine-modified hollow fiber membrane with a structure different from that obtained by the immersion method.

Claims

1. A method for preparing a fluorine-modified hollow fiber membrane, characterized in that, The preparation method includes the following steps: Step 1: Prepare a casting solution containing polyolefin material and diluent; Step 2: The casting solution is used to prepare hollow fiber membrane precursors through a spinning process; Step 3: Pass the hollow fiber membrane precursor through an air gap, a cooling tank, and a solvent exchange tank in sequence to obtain a semi-finished membrane after removing the diluent; the coolant in the cooling tank is at least one of perfluoropolyether and dihydroxy perfluoropolyether. Step 4: Dry the semi-finished membrane to obtain a fluorine-modified hollow fiber membrane; The polyolefin material is selected from poly4-methyl-1-pentene or polypropylene; The diluent is selected from at least one of dioctyl oxalate, glyceryl triacetate, dibutyl phthalate, and dioctyl phthalate. In step 3, an extractant is provided in the solvent exchange tank, and the diluent is removed by extraction with the extractant.

2. The preparation method according to claim 1, characterized in that, The casting solution contains 20 wt% to 50 wt% polyolefin material and 50 wt% to 80 wt% diluent.

3. The preparation method according to claim 1, characterized in that, In step 2, the spinning process involves extruding the casting solution through a spinneret to form hollow fibers. The difference between the outer diameter and the inner diameter of the spinneret is 5 μm to 500 μm.

4. The preparation method according to claim 3, characterized in that, The difference between the outer diameter and the inner diameter of the spinneret is 150 μm to 500 μm.

5. The preparation method according to claim 3, characterized in that, The inner diameter of the spinneret is 50μm to 500μm, and the outer diameter of the spinneret is 100μm to 1000μm.

6. The preparation method according to claim 3, characterized in that, The inner diameter of the spinneret is 100μm to 300μm, and the outer diameter of the spinneret is 200μm to 800μm.

7. The preparation method according to claim 1, characterized in that, The gas in the air gap is selected from at least one of air, nitrogen, and carbon dioxide, and the air gap is 10 mm to 500 mm.

8. The preparation method according to claim 7, characterized in that, The air gap is 50 mm to 300 mm.

9. The preparation method according to claim 3, characterized in that, The extrusion spinning speed is 20 m / min to 300 m / min.

10. The preparation method according to claim 9, characterized in that, The extrusion spinning speed is 20 m / min to 100 m / min.

11. The preparation method according to claim 1, characterized in that, The temperature of the coolant in the cooling pool is 25℃~65℃.

12. The preparation method according to claim 11, characterized in that, The temperature of the coolant in the cooling pool is 30℃~60℃.

13. The preparation method according to claim 1, characterized in that, The extractant is selected from at least one of ethanol, isopropanol, N,N-dimethylformamide, ethyl acetate, amyl acetate, dichloromethane, and ethylene glycol butyl ether.

14. The preparation method according to claim 12, characterized in that, The extraction time in the solvent exchange tank is 10 h to 100 h.

15. The fluorine-modified hollow fiber membrane prepared by the preparation method according to any one of claims 1-14.

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