Fluorine surface modified hollow fiber membrane material and preparation method thereof

Abstract

The invention provides a fluorine surface modified hollow fiber membrane material as well as a preparation method and application thereof, specifically, the fluorine surface modified hollow fiber membrane material is prepared by the following preparation method, and the preparation method comprises the following steps: step 1, preparing a membrane casting solution containing a polyolefin material and a diluent; step 2, preparing a hollow fiber membrane filament precursor from the membrane casting solution through a spinning process; step 3, enabling the hollow fiber membrane filament precursor to sequentially pass through an air gap, a cooling pool and a solvent exchange pool to obtain a semi-finished product membrane after the diluent is removed; the cooling liquid in the cooling tank is perfluoropolyether and dihydroxy perfluoropolyether; and step 4, drying the semi-finished product membrane to obtain the fluorine surface modified hollow fiber membrane. According to the method, the cooling link in the spinning process is utilized, the hollow fiber membrane is cooled at a high speed, fluorine modification is carried out on the hollow fiber membrane, a chemical functional group containing fluorine is formed, and the biocompatibility of the hollow fiber membrane is powerfully improved.

Description

Technical Field

[0001] The present invention relates to the technical field of material surface modification, and more specifically to a fluorine surface modified hollow fiber membrane material and a preparation method thereof. Background Art

[0002] Membrane oxygenator, also known as membrane artificial lung, is a disposable artificial device that can exchange blood and gas. It is mainly used for extracorporeal circulation support during critical rescue or disease treatment. It is the core component of the current extracorporeal membrane oxygenation (ECMO) equipment, mechanical perfusion equipment, and donor organ mechanical perfusion protection equipment. When the system is running, the patient's blood flows outside the hollow fiber membrane, and oxygen is injected into the membrane. The carbon dioxide in the blood and the oxygen in the membrane filament are replaced by pressure difference to achieve the gas exchange function of the lungs. This requires the membrane material to have both good air permeability and long-term hydrophobicity to meet the requirements of continuous operation for weeks or even months in the clinic. Therefore, for the membrane oxygenator, the most critical component is the hollow fiber membrane material, and the performance of the membrane material determines the performance of the oxygenator. In addition, since the membrane material will be in direct contact with the blood, the membrane material used also needs to have excellent blood compatibility.

[0003] EP2295132A1 proposes a preparation strategy for an antithrombotic extracorporeal blood circuit and its components, including a hollow fiber membrane, a blood tube and a filter, and their applications in related directions such as blood filtration, hemodialysis, hemodiafiltration, blood concentration, and blood oxygenation, wherein the use of an anticoagulant can be avoided. The hollow fiber membrane defined in the document includes fluorinated macromolecules through a blending process. In order to achieve the effect of reducing thrombosis, a large amount of such fluorinated macromolecules must be used. CN113316481A proposes a dialyzer of a fluorinated hollow fiber membrane, and the hollow fiber membrane defined in the document includes fluorinated macromolecules through a blending process. In order to achieve a certain biocompatibility improvement effect, a large amount of fluorinated macromolecules also need to be used. However, for the hot spinning process of the hollow fiber membrane, the method of improving the biocompatibility of the membrane by blending a large amount of fluorinated macromolecules in the casting liquid is easy to affect the membrane forming process and cause membrane degradation, which is not conducive to the continuous production of the membrane. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to propose a method for improving the preparation technology of hollow fiber membranes by adjusting the cooling process, making full use of the coolant in the preparation process of the hollow fiber membranes to obtain a fluorine-surface-modified hollow fiber membrane.

[0005] The purpose of the present invention is to use coolant to improve the process of preparing hollow fiber membranes by thermally induced phase separation (TIPS) method, and add fluorine element to the surface of hollow fiber membrane under the action of fluorine-containing coolant, so as to form fluorine-related chemical groups on the surface of fiber membrane.

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

[0007] Step 1, preparing a casting solution containing a polyolefin material and a diluent;

[0008] Step 2, preparing a hollow fiber membrane precursor by a spinning process using a membrane casting solution;

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

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

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

[0012] Furthermore, the polyolefin material is selected from poly-4-methyl-1-pentene and polypropylene.

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

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

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

[0016] Furthermore, 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] Further, the speed of extrusion spinning is 20 m / min to 300 m / min. Preferably, the speed of extrusion spinning 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] Furthermore, in step 3, an extractant is provided in the solvent exchange tank, and the diluent is removed by extraction with the extractant; the extractant is selected from at least one of ethanol, isopropanol, N,N-dimethylformamide, ethyl acetate, amyl acetate, dichloromethane and ethylene glycol butyl ether; and the extraction time in the solvent exchange tank is 10h to 100h.

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

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

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

[0023] Beneficial Effects

[0024] The present invention directly modifies the hollow fiber membrane in the cooling process by designing the cooling liquid, so that the hollow fiber membrane forms a chemical group containing fluorine, thereby 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 link in the spinning process. By designing and screening the coolant, the hollow fiber membrane is cooled at a faster speed, and at the same time, fluorine-modified hollow fiber membrane is carried out to form chemical functional groups containing fluorine, thereby effectively improving the biocompatibility of the hollow fiber membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an electron microscope photograph of the fiber membrane obtained by conventional method.

[0027] Figure 2 The electron microscope photograph of the fiber membrane obtained by the method of the present invention is shown in FIG.

[0028] Figure 3 This is the infrared spectrum of the fiber membrane obtained by the conventional method of Comparative Example 1.

[0029] Figure 4 The infrared spectrum of the fiber membrane obtained by the method of the present invention is shown in FIG.

[0030] Figure 5 This is the infrared spectrum of the fiber membrane obtained by Comparative Example 2. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but it should not be understood as limiting the scope of the implementation of the present invention. The technical solution of the present invention does not limit the device of the cooling liquid, because those skilled in the art can design a cooling pool and other devices according to specific experimental needs under the conditions of the hollow fiber membrane spinning.

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

[0033] Step 1, preparing a casting solution containing a polyolefin material and a diluent;

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

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

[0036] Step 2, preparing a hollow fiber membrane precursor by a spinning process using a membrane casting solution;

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

[0038] Step 3, passing the hollow fiber membrane precursor through an air gap, a cooling pool and a solvent exchange pool in sequence to obtain a semi-finished membrane after removing the diluent; the coolant in the cooling pool is at least one of perfluoropolyether and bishydroxy 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 of the air gap is 50 mm to 300 mm, for example, 100 mm or 200 mm.

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

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

[0042] Step 4, drying the semi-finished membrane to obtain a fluorine surface-modified hollow fiber membrane;

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

[0044] The fluorine surface-modified hollow fiber membrane provided by the present invention can be used as a medium for blood-gas exchange in the process of extracorporeal membrane oxygenation.

[0045] Example 1 Preparation of fluorine surface modified hollow fiber membrane

[0046] Step 1, melting a raw material containing 30% poly-4-methyl-1-pentene and 70% dibutyl phthalate in a twin-screw extruder, stirring, and degassing 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 at a spinning speed of 35 m / min to obtain a hollow fiber membrane precursor;

[0048] Step 3, passing the hollow fiber membrane precursor through an air gap, soaking and cooling in a cooling pool, and extracting in an exchange pool for 12 hours to obtain a semi-finished membrane after removing the diluent; wherein the space gap of the air gap is 100 mm, the gas in the air gap is air, the coolant in the cooling pool is a perfluoropolyether at 30°C, and the extractant in the exchange pool is an ethanol solvent;

[0049] Step 4: drying the semi-finished membrane at 80° C. for 12 h to obtain a fluorine surface-modified hollow fiber membrane.

[0050] Example 2 Preparation of fluorine surface modified hollow fiber membrane

[0051] Step 1, melting a raw material containing 30% poly-4-methyl-1-pentene and 70% triacetin in a twin-screw extruder, stirring, and degassing to obtain a casting solution;

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

[0053] Step 3, passing the hollow fiber membrane precursor through an air gap, soaking and cooling in a cooling pool, and extracting in an exchange pool for 16 hours to obtain a semi-finished membrane after removing the diluent; wherein the space gap of the air gap is 200 mm, the gas in the air gap is air, the coolant in the cooling pool is 40°C dihydroxy perfluoropolyether, and the extractant in the exchange pool is isopropanol solvent;

[0054] Step 4: drying the semi-finished membrane at 100° C. for 10 h to obtain a fluorine surface-modified hollow fiber membrane.

[0055] Example 3 Preparation of fluorine surface modified hollow fiber membrane

[0056] Step 1, melting a raw material containing 40% poly-4-methyl-1-pentene and 60% dioctyl phthalate in a twin-screw extruder, stirring, and degassing to obtain a film casting solution;

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

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

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

[0060] Example 4 Preparation of fluorine surface modified hollow fiber membrane

[0061] Step 1, melting a raw material containing 40% poly-4-methyl-1-pentene and 60% triacetin in a twin-screw extruder, stirring, and degassing to obtain a casting solution;

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

[0063] Step 3, passing the hollow fiber membrane precursor through an air gap, soaking and cooling in a cooling pool, and extracting in an exchange pool for 20 hours to obtain a semi-finished membrane after removing the diluent; wherein the space gap of the air gap is 200 mm, the gas in the air gap is air, the coolant in the cooling pool is 40°C dihydroxy perfluoropolyether, and the extractant in the exchange pool is dichloromethane;

[0064] Step 4: drying the semi-finished membrane at 100° C. for 10 h to obtain a fluorine surface-modified hollow fiber membrane.

[0065] Example 5 Preparation of fluorine surface modified hollow fiber membrane

[0066] Step 1, melting the raw materials containing 30% polypropylene and 70% dioctyl oxalate in a twin-screw extruder, stirring, and degassing to obtain a film casting solution;

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

[0068] Step 3, passing the hollow fiber membrane precursor through an air gap, soaking and cooling in a cooling pool, and extracting in an exchange pool 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 pool is 60°C perfluoropolyether, and the extractant in the exchange pool is N,N-dimethylformamide;

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

[0070] Comparative Example 1 Preparation of conventional hollow fiber membrane

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

[0072] Comparative Example 2 Preparation of fluorine-modified hollow fiber membrane

[0073] Step 1, melting a raw material containing 40% poly-4-methyl-1-pentene and 60% dibutyl phthalate in a twin-screw extruder, stirring, and degassing to obtain a casting solution;

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

[0075] Step 3, passing the hollow fiber membrane precursor through an air gap, soaking and cooling in a cooling pool, and extracting 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 coolant in the cooling pool is 30° C. water, and the extractant in the exchange pool is an ethanol solvent;

[0076] Step 4, drying the semi-finished membrane at 80° C. for 12 h to obtain a hollow fiber membrane;

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

[0078] Test results

[0079] First, the surface and cross section of the hollow fiber were observed by scanning electron microscopy. Figure 1 The figure shows a scanning electron microscope photograph of the poly 4-methyl-1-pentene hollow fiber membrane obtained in Example 1 using conventional water coolant. It can be seen that the outer skin of the hollow fiber membrane is flat and smooth, and the cross section has a distinct rough morphology.

[0080] The scanning electron microscope photo of the hollow fiber membrane obtained in Example 1 is as follows: Figure 2 As shown, compared with the conventional process, the method of the present invention does not affect the dense morphology structure of the outer skin layer, thereby ensuring the mechanical properties and permeability of the membrane filaments.

[0081] Furthermore, the chemical structure of the hollow fiber membrane surface was analyzed using infrared spectroscopy. Figure 3-5 As shown. It can be seen that compared with the hollow fiber membrane obtained by conventional process, the hollow fiber membrane obtained by this method retains the original characteristic peaks, which proves that the main components of the hollow fiber membrane are maintained. At the same time, the hollow fiber membrane prepared by this method has a peak at 1026cm -1 and 1058cm -1 There is an obvious fluorine-containing characteristic peak at 1663 cm -1There are also characteristic peaks caused by the stretching movement of carboxylic acid and carbonyl groups. This is a typical product of fluoride degradation. The acetal unit in the fluoride will be hydrolyzed into carbonyl groups after contacting with moisture in the air, 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 by infrared spectroscopy ( Figure 4 As shown). By comparison, it can be seen that the hollow fiber membrane prepared by the method of the present invention in Example 1 has strong characteristic peaks of CF and carbonyl, indicating that the surface modification of the hollow fiber membrane can be effectively achieved by the method of the present invention. However, the surface of the hollow fiber membrane obtained by Comparative Example 2 only has the characteristic peak of CF, and does not have the characteristic peak of carbonyl. The above results show that this method obtains a fluorine surface modified hollow fiber membrane with a different structure from the immersion method.

Claims

1. A method for preparing a fluorine surface-modified hollow fiber membrane, characterized in that: The preparation method comprises the following steps: Step 1, preparing a casting solution containing a polyolefin material and a diluent; Step 2, preparing a hollow fiber membrane precursor by a spinning process using a membrane casting solution; Step 3, passing the hollow fiber membrane precursor through an air gap, a cooling pool and a solvent exchange pool in sequence to obtain a semi-finished membrane after removing the diluent; the coolant in the cooling pool is at least one of perfluoropolyether and bishydroxy perfluoropolyether; Step 4: Dry the semi-finished membrane to obtain a fluorine-surface-modified hollow fiber membrane.

2. The preparation method according to claim 1, characterized in that The content of the polyolefin material in the casting solution is 20wt% to 50wt%, and the content of the diluent is 50wt% to 80wt%; Preferably, the polyolefin material is selected from poly-4-methyl-1-pentene and polypropylene; Preferably, the diluent is selected from at least one of dioctyl oxalate, triacetin, dibutyl phthalate and dioctyl phthalate.

3. The preparation method according to claim 1, characterized in that In step 2, the spinning process is to extrude the casting solution through a spinneret to form a hollow fiber, and the difference between the outer diameter of the spinneret and the inner diameter of the spinneret is 5 μm to 500 μm; Preferably, the difference between the outer diameter of the spinneret and the inner diameter of the spinneret is 150 μm to 500 μm.

4. The preparation method according to claim 3, characterized in that The inner diameter of the spinneret is 50 μm to 500 μm, and the outer diameter of the spinneret is 100 μm to 1000 μm; Preferably, the inner diameter of the spinneret is 100 μm to 300 μm, and the outer diameter of the spinneret is 200 μm to 800 μm.

5. The preparation method according to claim 1, characterized in that: 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.

6. The preparation method according to claim 3, characterized in that: The speed of extrusion spinning is 20m / min~300m / min; Preferably, the speed of extrusion spinning is 20 m / min to 100 m / min.

7. The preparation method according to claim 1, characterized in that: 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.

8. The preparation method according to claim 1, characterized in that: In step 3, an extractant is provided in the solvent exchange tank, and the diluent is removed by extraction with the extractant; Preferably, the extractant is selected from at least one of ethanol, isopropanol, N,N-dimethylformamide, ethyl acetate, amyl acetate, dichloromethane and ethylene glycol butyl ether; Preferably, the extraction time in the solvent exchange tank is 10 h to 100 h.

9. The fluorine surface-modified hollow fiber membrane prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the fluorine surface modified hollow fiber membrane according to claim 9, characterized in that: The application is to use the fluorine surface modified hollow fiber membrane as a medium for blood-gas exchange during extracorporeal membrane oxygenation.

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