Surface coating in-situ modified hollow fiber membrane material and preparation method thereof

Abstract

The invention provides a surface coating in-situ modified hollow fiber membrane material and a preparation method thereof. The preparation method comprises the following steps: step 1, preparing a membrane casting solution; preparing a hollow fiber membrane filament precursor from the membrane casting solution through a spinning process; step 2, 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 membrane; the cooling liquid in the cooling pool is an ethylene glycol aqueous solution treated by plasma; and step 3, carrying out surface treatment on the semi-finished product membrane again by utilizing plasma to obtain the hollow fiber membrane with the surface polyethylene glycol coating structure. Components of the cooling liquid are fully utilized, plasma polymerization treatment is combined, in-situ modification is carried out on the surface of the hollow fiber membrane, and the polyethylene glycol coating is rapidly and efficiently formed on the surface of the hollow fiber membrane.

Description

Technical Field

[0001] The invention belongs to the technical field of material surface modification, and specifically provides a hollow fiber membrane material with surface coating in-situ modification and a preparation method thereof. Background Art

[0002] The composition and structure of the material surface are important factors that determine the application effect of hollow fiber membranes. Hollow fiber membranes used in membrane oxygenators as blood contact materials need to have stable chemical and mechanical properties, good anti-leakage performance, blood compatibility and good gas exchange performance. These characteristics can increase the use time and efficiency of blood gas exchange membranes and reduce a series of immune reactions such as hemolysis and coagulation.

[0003] When hollow fiber membrane materials, as foreign matter, come into direct contact with blood, they will quickly trigger a series of reactions, affecting the human coagulation system and immune system, and eventually leading to thrombosis or hemolysis. Therefore, it is extremely important to improve the blood compatibility of membrane materials. The development and research of hollow fiber membrane materials for modern membrane oxygenators focuses on surface coatings. By coating the fiber surface with materials with good oxygen permeability and anti-coagulation properties, the efficiency of artificial membrane lungs can be improved. At the same time, the thin and dense surface layer is in contact with the blood, preventing plasma penetration, and can be used clinically for a long time. At present, there are a variety of technologies and schemes for preparing coatings on the surface of hollow fiber membranes. However, the existing immersion coating method also has the disadvantages of complex components of the coating liquid, long immersion time, fiber membrane pretreatment, and inability to couple with existing equipment for preparing hollow fiber membranes. Summary of the invention

[0004] In view of the above problems existing in the prior art, the purpose of the present invention is to propose a technology for preparing a hollow fiber membrane with a surface coating by adjusting the cooling process and the post-treatment process, making full use of the coolant in the hollow fiber membrane preparation process, and combining plasma polymerization treatment to realize the in situ formation of a polyethylene glycol coating on the surface of the hollow fiber membrane, so as to obtain a hollow fiber membrane material with an in situ modified surface coating.

[0005] The purpose of the present invention is to improve the cooling process in the process of preparing hollow fiber membranes by the thermally induced phase separation (TIPS) method, use an aqueous solution of ethylene glycol treated with plasma, and while effectively achieving the cooling effect of the fiber membrane, utilize subsequent plasma polymerization treatment to polymerize the components of ethylene glycol into a polyethylene glycol-like structure, thereby quickly and efficiently forming a coating on the surface of the hollow fiber membrane.

[0006] The first aspect of the present invention provides a method for preparing a hollow fiber membrane material with in-situ surface coating modification, the preparation method comprising the following steps:

[0007] Step 1, preparing a casting solution containing a polyolefin material and a diluent, and preparing a hollow fiber membrane precursor by a spinning process using the casting solution;

[0008] Step 2, 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 a plasma-treated ethylene glycol aqueous solution;

[0009] Step 3: placing the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ modified surface coating.

[0010] 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%.

[0011] Furthermore, the polyolefin material is selected from poly-4-methyl-1-pentene or polypropylene.

[0012] Furthermore, the diluent is selected from at least one of dioctyl adipate, triacetin, dibutyl phthalate and dioctyl phthalate.

[0013] Furthermore, in step 1, 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.

[0014] Furthermore, 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.

[0015] Furthermore, the air gap is 10 mm to 500 mm. Preferably, the air gap is 50 mm to 300 mm.

[0016] Further, the speed of extrusion spinning is 20 m / min to 200 m / min. Preferably, the speed of extrusion spinning is 20 m / min to 80 m / min.

[0017] Furthermore, the cooling liquid of the cooling pool is selected from a plasma-treated ethylene glycol aqueous solution; the temperature of the cooling pool is 25° C. to 66° C. The content of ethylene glycol in the ethylene glycol aqueous solution is 50% to 80%.

[0018] Furthermore, the cooling liquid is an activated solution produced by treating an ethylene glycol aqueous solution using an atmospheric pressure plasma technique, and the atmospheric pressure plasma treatment time is 20 min-180 min, preferably 30 min-120 min.

[0019] Furthermore, in step 2, 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.

[0020] Furthermore, in step 3, the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.01 to 1:0.1, and the plasma treatment time is 10 minutes to 45 minutes.

[0021] The second aspect of the present invention provides a hollow fiber membrane material with surface coating in-situ modification prepared by the above preparation method.

[0022] The third aspect of the present invention provides the use of the above-mentioned surface coating in-situ modified hollow fiber membrane material, which is used as a medium for blood gas exchange in the process of extracorporeal membrane oxygenation.

[0023] Beneficial Effects

[0024] 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 cooling liquid and utilizing plasma to activate the activity of the ethylene glycol aqueous solution, the surface of the hollow fiber membrane is activated and modified while ensuring the cooling of the hollow fiber membrane. The subsequent plasma polymerization treatment forms a polyethylene glycol coating, thereby quickly and efficiently forming a coating on the surface of the hollow fiber membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an electron microscope photograph of the hollow fiber membrane obtained by the conventional method of Comparative Example 1.

[0026] Figure 2 This is an electron microscope photograph of a hollow fiber membrane obtained by the method of Example 1 of the present invention.

[0027] Figure 3 This is the infrared spectrum of the hollow fiber membrane obtained by the conventional method of Comparative Example 1.

[0028] Figure 4 This is an infrared spectrum of the hollow fiber membrane obtained by the method of Example 1 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings, but they should not be construed as limiting the applicable scope of the present invention.

[0030] The technical solution of the present invention does not limit the structure of the cooling pool immersed in the coolant and the structure of the solvent exchange pool, because those skilled in the art can design the above-mentioned device according to specific experimental needs after determining the conditions for hollow fiber membrane spinning.

[0031] The technical solution of the present invention does not limit the plasma generating device in the plasma activated ethylene glycol solution, because those skilled in the art can design atmospheric pressure plasma generating devices such as plasma jet and dielectric barrier discharge according to specific experimental needs under the conditions of determining the discharge gas and the target to be treated. At the same time, in the technical solution of the present invention, the discharge power of the plasma is not limited, because the discharge power generated by different discharge devices is different, and those skilled in the art can adjust the discharge power according to the generating device, gas and flow rate, and the situation of the solution to be treated, and only need to ensure that the effect is produced.

[0032] Some specific embodiments of the present invention provide a method for preparing a hollow fiber membrane material with in-situ surface coating modification, the method comprising the following steps:

[0033] Step 1, melting a polyolefin material and a diluent in a twin-screw extruder, stirring, degassing, and then obtaining a casting solution, and extruding and spinning the casting solution through a spinneret to form a hollow fiber membrane precursor; the sum of the content of the polyolefin material and the diluent is 100%;

[0034] In some specific embodiments, in step 1, the content of the polyolefin material in the casting solution is 20wt% to 50wt%, and the content of the diluent is 50wt% to 80wt%. 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%.

[0035] In some specific embodiments, in step 1, the polyolefin material is selected from poly-4-methyl-1-pentene or polypropylene.

[0036] In some specific embodiments, in step 1, the diluent is selected from at least one of dioctyl adipate, triacetin, dibutyl phthalate, and dioctyl phthalate.

[0037] In some specific embodiments, in step 2, 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.

[0038] In some specific embodiments, 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, 500 μm, 600 μm, 700 μm, 800 μm.

[0039] In some specific embodiments, the speed of extrusion spinning is 20 m / min to 200 m / min. Preferably, the speed of extrusion spinning is 20 m / min to 80 m / min, for example, 30 m / min, 40 m / min, 50 m / min, 60 m / min, 70 m / min.

[0040] 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.

[0041] Step 2, 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 a plasma-treated ethylene glycol aqueous solution;

[0042] In some specific embodiments, the gas in the air gap is at least one selected from air, nitrogen and carbon dioxide, and the air gap is 50 mm to 300 mm, for example, 100 mm or 200 mm.

[0043] Furthermore, the cooling liquid of the cooling pool is selected from a plasma-treated ethylene glycol aqueous solution; the temperature of the cooling pool is 25°C to 66°C, for example, 30°C, 40°C, 50°C, 60°C. The content of ethylene glycol in the ethylene glycol aqueous solution is 50% to 80%, for example, 60% or 70%.

[0044] Further, the cooling liquid is an activated solution produced by treating an ethylene glycol aqueous solution using an atmospheric pressure plasma technique, and the atmospheric pressure plasma treatment time is 20 min-180 min, preferably 30 min-120 min. For example, 30 min, 40 min, 50 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min.

[0045] In some specific embodiments, in step 2, 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.

[0046] Step 3: placing the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ modified surface coating.

[0047] Furthermore, in step 3, the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.01 to 1:0.1, and the plasma treatment time is 10 min to 45 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min.

[0048] The method of the present invention utilizes a special coolant to replace the conventional coolant of the thermally induced phase separation (TIPS) method, so that during the cooling process of the hollow fiber membrane precursor, the plasma activated solution is activated to form a coating on the surface of the hollow fiber membrane quickly and efficiently.

[0049] The hollow fiber membrane obtained by the preparation method of the present invention has a stable and uniform coating and is quickly prepared, and can be used on a large scale as a medium for blood-gas exchange in the process of extracorporeal membrane oxygenation.

[0050] Example 1

[0051] Step 1, melting a raw material containing 30wt% poly-4-methyl-1-pentene and 70wt% dibutyl phthalate in a twin-screw extruder, stirring, and degassing to obtain a casting solution; ejecting the casting solution through a spinneret with an inner diameter of 100μm and an outer diameter of 500μm at a spinning speed of 40m / min to obtain a hollow fiber membrane precursor;

[0052] Step 2: The hollow fiber membrane precursor is passed through an air gap, a cooling pool, and a solvent exchange pool in sequence to obtain a semi-finished membrane after the diluent is removed; the coolant in the cooling pool is a plasma-treated ethylene glycol aqueous solution at a temperature of 25°C. The ethylene glycol content in the ethylene glycol aqueous solution is 50%, the plasma treatment is an atmospheric pressure plasma treatment, and the treatment time is 30 minutes. The air gap is 100 mm, the gas in the air gap is air, and the extractant in the solvent exchange pool is ethanol.

[0053] Step 3: Place the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ surface coating modification, wherein the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.01, and the plasma treatment time is 30 minutes.

[0054] Example 2

[0055] 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; 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;

[0056] Step 2: The hollow fiber membrane precursor is passed through an air gap, a cooling pool, and a solvent exchange pool in sequence to obtain a semi-finished membrane after the diluent is removed; the coolant in the cooling pool is a plasma-treated ethylene glycol aqueous solution at a temperature of 50°C. The ethylene glycol content in the ethylene glycol aqueous solution is 80%, and the atmospheric pressure plasma treatment time is 40 minutes. The air gap is 200 mm, the gas in the air gap is air, and the extractant in the solvent exchange pool is isopropanol.

[0057] Step 3: Place the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ surface coating modification, wherein the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.05, and the plasma treatment time is 40 minutes.

[0058] Example 3

[0059] Step 1, melting a raw material containing 35% poly-4-methyl-1-pentene and 75% dioctyl phthalate in a twin-screw extruder, stirring, and degassing to obtain a casting solution; 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;

[0060] Step 2: The hollow fiber membrane precursor is passed through an air gap, a cooling pool, and a solvent exchange pool in sequence to obtain a semi-finished membrane after the diluent is removed; the coolant in the cooling pool is a plasma-treated ethylene glycol aqueous solution at a temperature of 40°C. The ethylene glycol content in the ethylene glycol aqueous solution is 70%, and the atmospheric pressure plasma treatment time is 90 minutes. The air gap is 300 mm, the gas in the air gap is air, and the extractant in the solvent exchange pool is ethyl acetate.

[0061] Step 3: Place the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ surface coating modification, wherein the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.06, and the plasma treatment time is 40 minutes.

[0062] Example 4

[0063] Step 1, dissolving 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; 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;

[0064] Step 2: The hollow fiber membrane precursor is passed through an air gap, a cooling pool, and a solvent exchange pool in sequence to obtain a semi-finished membrane after the diluent is removed; the coolant in the cooling pool is a plasma-treated ethylene glycol aqueous solution at a temperature of 60°C. The ethylene glycol content in the ethylene glycol aqueous solution is 65%, and the atmospheric pressure plasma treatment time is 100 minutes. The air gap is 200 mm, the gas in the air gap is nitrogen, and the extractant in the solvent exchange pool is dichloromethane.

[0065] Step 3: Place the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ surface coating modification, wherein the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.08, and the plasma treatment time is 35 minutes.

[0066] Example 5

[0067] Step 1, dissolving a raw material containing 20% ​​polypropylene and 80% dioctyl oxalate in a twin-screw extruder, stirring, and degassing to obtain a casting solution; 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 35 m / min to obtain a hollow fiber membrane precursor;

[0068] Step 2: The hollow fiber membrane precursor is passed through an air gap, a cooling pool, and a solvent exchange pool in sequence to obtain a semi-finished membrane after the diluent is removed; the coolant in the cooling pool is a plasma-treated ethylene glycol aqueous solution at a temperature of 45°C. The ethylene glycol content in the ethylene glycol aqueous solution is 55%, and the atmospheric pressure plasma treatment time is 120 minutes. The air gap is 50 mm, the gas in the air gap is nitrogen, and the solvent in the solvent exchange pool is N,N-dimethylformamide.

[0069] Step 3: Place the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ surface coating modification, wherein the plasma is generated by discharge of nitrogen and oxygen, the gas ratio is 1:0.09, and the plasma treatment time is 35 minutes.

[0070] Comparative Example 1

[0071] The same method as in Example 1 is used except that conventional water is used as the cooling liquid.

[0072] Effect Experiment

[0073] 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.

[0074] 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 morphology of the inner cortex, ensuring the mechanical properties and permeability of the membrane. However, the outer cortex of the fiber membrane presents a relatively rough coating morphology, confirming the successful preparation of the hollow fiber membrane with in-situ surface coating modification.

[0075] Furthermore, the hollow fiber membranes obtained in Example 1 and Comparative Example 2 were compared by infrared spectroscopy. Figure 3 The surface of the hollow fiber membrane obtained by (as shown) is the infrared spectrum of the conventional poly-4-methyl-1-pentene hollow fiber membrane, and does not have other characteristic peaks. By comparison, it can be seen that Example 1 ( Figure 4 The hollow fiber membrane prepared by the method of the present invention retains the characteristic peaks of conventional fiber membranes and also has a peak at 1550cm -1 ~1750cm -1 Characteristic peaks such as C=O, CN, and CC appeared between them, confirming the presence of polyethylene glycol components, indicating that the method of the present invention can form polyethylene glycol structures in situ on the surface of the hollow fiber membrane. The above results show that the method obtains a hollow fiber membrane material with in-situ surface coating modification.

Claims

1. A method for preparing a hollow fiber membrane material with in-situ surface coating modification, characterized in that: The preparation method comprises the following steps: Step 1, preparing a casting solution containing a polyolefin material and a diluent, and preparing a hollow fiber membrane precursor by a spinning process using the casting solution; Step 2, 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 a plasma-treated ethylene glycol aqueous solution; Step 3: placing the cooled semi-finished membrane under plasma for polymerization treatment to obtain a hollow fiber membrane with in-situ modified surface coating.

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 or polypropylene; Preferably, the diluent is selected from at least one of dioctyl adipate, triacetin, dibutyl phthalate and dioctyl phthalate.

3. The preparation method according to claim 1, characterized in that In step 1, 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, in step 1, the difference between the outer diameter of the spinneret and the inner diameter of the spinneret is 150 μm to 500 μm; Preferably, 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; More 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.

4. The preparation method according to claim 1, characterized in that The air gap is 10 mm to 500 mm; the gas in the air gap is at least one selected from air, nitrogen and carbon dioxide; Preferably, the air gap is 50 mm to 300 mm.

5. The preparation method according to claim 3, characterized in that: The speed of extrusion spinning is 20m / min~200m / min; Preferably, the speed of extrusion spinning is 20 m / min to 80 m / min.

6. The preparation method according to claim 1, characterized in that: The temperature of the cooling pool is 25°C to 66°C; Preferably, the content of ethylene glycol in the ethylene glycol aqueous solution is 50% to 80%; Preferably, the cooling liquid is an activated solution produced by treating an ethylene glycol aqueous solution using an atmospheric pressure plasma technique, and the atmospheric pressure plasma treatment time is 20 min-180 min.

7. The preparation method according to claim 1, characterized in that: In step 2, 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.

8. The preparation method according to claim 1, characterized in that: In step 3, the plasma is generated by discharge of nitrogen and oxygen, and the gas ratio is 1: 0.01~1:0.1, and the plasma treatment time is 10min~45min.

9. The hollow fiber membrane material with in-situ surface coating modification obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the surface coating in-situ modified hollow fiber membrane material according to claim 9, characterized in that: The application is to use the hollow fiber membrane material with in-situ surface coating modification as a medium for blood-gas exchange in the process of extracorporeal membrane oxygenation.

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