Microporous hollow fiber membrane, and preparation method therefor and use thereof

Abstract

A microporous hollow fiber membrane, having an inner surface for contacting a protein-containing solution and an outer surface for discharging a filtrate. The section from the inner surface to the outer surface is of a gradient pore diameter structure having an average pore diameter varying from 70 nm to 20 nm, and is of a bicontinuous net structure; pores in the inner surface of the hollow fiber membrane are micropores of 0.2-3 μm, and micropores of 0.01-0.1 μm are formed in the outer surface; and the microporous hollow fiber membrane has an inner diameter of 100-800 μm, and a wall thickness of 60-500 μm. In addition, also involved are a preparation method for and use of a microporous hollow fiber membrane.

Description

A microporous hollow fiber membrane, its preparation method and application

[0001] This invention claims priority to the earlier application filed on April 26, 2024, with China National Intellectual Property Administration, patent application number 202410515159.0, entitled "A Microporous Hollow Fiber Membrane and Its Preparation Method and Application". The entire contents of the aforementioned earlier application are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of polymer film technology, specifically to a microporous hollow fiber membrane, its preparation method, and its application. Background Technology

[0003] Monoclonal antibodies (MAbs) are a type of biological macromolecular drug produced by modern biotechnology for the diagnosis, treatment and prevention of diseases. Compared with proteins, peptides, enzymes and cytokines produced by recombinant DNA technology, they are widely recognized and occupy a dominant position in the market.

[0004] Monoclonal antibodies (MCAbs) are produced through artificial hybridoma cell culture and undergo separation and purification processes including clarification, capture, purification, and virus filtration. This results in contamination from endogenously expressed retroviruses and exogenous viruses such as parvovirus. Therefore, virus filtration is crucial in the purification process of MAbs. Due to the physicochemical stability of parvovirus, membrane filtration utilizing size sieving can remove the virus more effectively. However, due to their small pore size, virus filtration membranes often face the risk of pore blockage by MAb aggregates and even the formation of a filter cake layer during application, leading to decreased membrane efficiency and maximum filtration capacity, thus increasing the cost of virus filtration. Furthermore, regarding protein aggregate blockage of filter membranes, some foreign studies have found that they account for only 1×10⁻⁶ of the total protein mass in the solution. -4 Even trace protein aggregates in the 20–40 nm size range are sufficient to cause significant membrane flux attenuation during virus filtration.

[0005] Currently, the main materials for existing virus filtration membranes are regenerated cellulose membranes, hydrophilically modified polyvinylidene fluoride (PVDF), and polyethersulfone (PES) membranes. In Asahi Kasei's patent (CN201780009989) regarding the BioEX series of virus filtration membranes, it is a hollow fiber membrane with a gradient pore structure capable of retaining 30-20 nm colloidal gold and partially retaining 15 nm colloidal gold. However, this membrane is easily blocked by unexpected impurities such as protein aggregates of 40 nm or larger.

[0006] Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a microporous hollow fiber membrane, its preparation method, and its application. It provides a microporous hollow fiber filter membrane formed using thermally induced phase separation (TIPS) with a gradient pore size ranging from 70 nm to 20 nm from the inner to outer surface of the hollow fiber membrane. This membrane can be used for the retention and filtration of viruses in the 20–70 nm range, reducing the probability of membrane clogging and failure in downstream viral filtration processes of biopharmaceuticals. It also has a certain compensatory effect on failures occurring in upstream viral filtration stages, improving the viral safety of the filtrate, and features high efficiency and high filtration capacity.

[0008] This invention provides a microporous hollow fiber membrane having an inner surface that contacts a protein-containing solution and an outer surface that discharges filtrate; the cross-section from the inner surface to the outer surface has a gradient pore size structure with an average pore size varying from 70 to 20 nm, and exhibits a bicontinuous network structure; the pores on the inner surface of the hollow fiber membrane are micropores of 0.2 to 3 μm, and the pores on the outer surface are micropores of 0.01 to 0.1 μm; the inner diameter of the membrane is 100 to 800 μm, and the wall thickness is 60 to 500 μm.

[0009] In some embodiments, the material of the microporous hollow fiber membrane is polyvinylidene fluoride.

[0010] In some embodiments, the pure water flux of the microporous hollow fiber membrane is 20–60 L / (m²). 2 The bubble point range of the microporous hollow fiber membrane is 1.7 to 3 bar. If the bubble point is too high, the average pore size will be too small, resulting in a small filtration flux. If the bubble point is too low, the cross-section will have large pores, which may result in poor filtration effect in practical applications.

[0011] This invention provides a method for preparing a microporous hollow fiber membrane, comprising:

[0012] Step 1: The core liquid, casting liquid 1, and casting liquid 2 are fed into a three-channel spinneret. The temperatures of the core liquid, casting liquid 1, and casting liquid 2, the spinning temperature, flow rate, and spinning speed of the spinneret are controlled to extrude hollow fiber nascent membrane filaments. The inner channel of the three-channel spinneret is the core liquid channel, the middle channel is the casting liquid 1 channel, and the outer channel is the casting liquid 2 channel.

[0013] Step 2: The hollow fiber nascent membrane filaments pass through the air gap section and enter the coagulation bath to solidify and form a membrane. Then, they are immersed in the extractant for extraction and dried to obtain a microporous hollow fiber membrane.

[0014] The core liquid is a sebacic acid ester, phthalic acid ester, adipate ester, citrate ester, or phosphate ester; the casting liquid 1 consists of 25-40 wt% polyvinylidene fluoride and 60-75 wt% solvent d1, and the casting liquid 2 consists of 40-60 wt% polyvinylidene fluoride and 40-60 wt% solvent d2.

[0015] In some embodiments, solvent d1 and solvent d2 are sebacic acid esters, phthalic acid esters, adipate esters, citrate esters, or phosphate esters.

[0016] Furthermore, the sebacate esters are dimethyl sebacate, di(iso)octyl sebacate, di-n-hexyl sebacate, or di-n-butyl sebacate, etc.; the phthalate esters are dimethyl phthalate, diethyl phthalate, di(2-ethylhexyl) phthalate (DEHP), or dibutyl phthalate, etc.; the adipate esters are dioctyl adipate, 2-n-hexyl adipate, octyl-n-decyl adipate, or diethylene glycol monobutyl ether adipate, etc.; and the citrate esters are trimethyl citrate, tributyl citrate (TBC), or acetylated tributyl citrate (ATBC), etc.

[0017] In some embodiments, the core fluid, solvent d1, and solvent d2 are at the melting point T of polyvinylidene fluoride. mp The above refers to ester organic solvents that form a homogeneous solution with polyvinylidene fluoride, and the core liquid and solvent d1, and solvent d1 and solvent d2 cannot both be orthophthalic esters.

[0018] Furthermore, the melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d1 is... mp-d1 Satisfying 10℃ < T mp -T mp-d1 At temperatures below 20℃, a bicontinuous network structure is formed, primarily characterized by liquid-liquid phase separation.

[0019] The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d2 mp-d2 Satisfying 2℃ < T mp -T mp-d2 <8℃, more preferably, solvent d2 has a melting point greater than 30℃, which makes it easier to form a structure with countless fine micropores distributed in the polymer skeleton.

[0020] The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% core fluid mp-b Satisfying 30℃ < T mp -T mp-b < 100℃, more preferably 30℃ < T mp -T mp-bAt temperatures below 50°C, the compatibility between the core fluid and the polymer is better than that between solvent d1 and the polymer, resulting in a loose and porous inner surface.

[0021] Furthermore, T mp-d2 -T mp-d1 <8℃, if the difference between the two is greater than 8℃, there is a risk of delamination during the film formation process of casting solution 1 and casting solution 2; 10℃ <T mp-d1 -T mp-b <40℃ means that the compatibility between solvent d1 and core liquid must be within a certain range. If it is less than 10℃, it is not easy to form a loose microporous structure on the inner surface, that is, it is impossible to obtain a pore size higher than the average pore size obtained by casting liquid 1 alone, and thus it is impossible to achieve a true gradient pore size. If it is greater than 40℃, the compatibility between core liquid and solvent d1 is too poor, which is not conducive to the smoothness of the inner surface and may form an uneven inner surface.

[0022] In some embodiments, the core liquid temperature ranges from 60 to 170°C, and the core liquid flow rate ranges from 3 to 30 mL / min; more preferably, it is from 80 to 140°C. If the core liquid temperature is too low, the inner structure of the membrane near the core liquid will solidify faster due to contact with the core liquid, which is much lower than the curing temperature, and the degree of mutual diffusion between the core liquid and the casting liquid 1 in the contact area will be low. Overall, due to the shortened coarsening time of the polymer-poor phase droplets during the liquid-liquid phase separation process, it will be difficult to form loose micropores, and thus it will be impossible to obtain a membrane with a pore size gradient. If the core liquid temperature is too high, during the spinning process, the curing and forming of the nascent membrane fibers in the air gap section will be too slow, making it difficult to form and difficult to continuously and stably spin.

[0023] The temperature range of casting solution 1 and casting solution 2 is 180–240°C, and the flow rate range of casting solution 1 and casting solution 2 is 2–15 mL / min. The spinning temperature range of the spinneret is 180–240°C. If the spinning temperature is too high, the casting solution will be difficult to form due to its low viscosity, and continuous and stable spinning will not be possible. If the spinning temperature is too low, the film fibers will be easily broken during the spinning process due to the high viscosity of the casting solution, and continuous and stable spinning will also be difficult. The coagulation bath is an organic solvent or water that is not miscible with polyvinylidene fluoride below 50°C. The temperature range of the coagulation bath is 10–50°C, more preferably 10–35°C. If the coagulation bath temperature is too high, the loose macroporous areas on the inner surface with pore sizes larger than the average pore size of the membrane tend to disappear, and the pore size on the outer surface will increase. In some embodiments, the length of the air gap section ranges from 10 to 150 mm, and the spinning rate ranges from 10 to 100 m / min. More preferably, the air gap length ranges from 20 to 130 mm. If the air gap is too short, the extruded casting solution will enter the low-temperature coagulation bath too quickly and the phase separation time will be too short, resulting in an overall average pore size of the formed hollow fiber cross-section that is too small. If the air gap is too long, the evaporation of solvent components in the high-temperature casting solution will increase, resulting in uneven pore distribution and small micropores on the outer surface of the membrane. Therefore, air gap environmental control methods are needed to improve the microstructure of the membrane near the outer surface and the micropore structure of the outer surface.

[0024] The specific components of the extractant are not specifically limited in this invention, including but not limited to one or more of ethanol, acetone, and isopropanol.

[0025] An application of a microporous hollow fiber membrane, including the use of microporous hollow fiber membranes in virus filtration in downstream processes of bioproducts.

[0026] Furthermore, the microporous hollow fiber membrane can be used for virus filtration in the downstream purification process of monoclonal antibody biopharmaceuticals. Beneficial effects:

[0027] This invention provides a microporous hollow fiber membrane that can filter protein aggregates of 40 nm or larger using its structural features. Theoretically, the flux and filtration capacity of this membrane during virus isolation will not be affected. The membrane has a gradient pore size structure ranging from 70 to 20 nm and exhibits a bicontinuous network structure. The inner surface pores are 0.2–3 μm micropores, while the outer surface has 0.01–0.1 μm micropores. Furthermore, the inner diameter of the membrane is adjustable from 100 to 800 μm, and the wall thickness can be 60–500 μm.

[0028] This invention provides a method for preparing the microporous hollow fiber membrane, which utilizes a combination of thermally induced phase separation and a three-channel spray plate to fabricate the membrane. By precisely controlling the formulation and spinning process in each channel, the microstructure of each region in the membrane structure can be controlled. This preparation process is simple and easy to implement. The prepared microporous hollow fiber membrane has a logarithmic removal rate of over 1 for colloidal gold at 70nm, 50nm, 30nm, and 20nm. It can be applied to virus filtration in downstream processes of biopharmaceuticals and is suitable for high-concentration biopharmaceutical culture media. In practical applications, it can improve the virus safety of biopharmaceutical processes. Attached Figure Description

[0029] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 is a schematic diagram of the capture site of colloidal gold by the membrane of the present invention;

[0031] Figure 2 is a schematic diagram of the preparation of the microporous hollow fiber membrane of the present invention;

[0032] Figure 3 shows the microstructure of the cross-section of the microporous hollow fiber membrane formed by the casting solution 1 in Example 1;

[0033] Figure 4 shows the microstructure of the cross-section of the microporous hollow fiber membrane formed by the casting solution 2 in Examples 1 and 2;

[0034] Figure 5 shows the microstructure of the inner surface of the microporous hollow fiber membrane in Example 1;

[0035] Figure 6 shows the microstructure of the outer surface of the microporous hollow fiber membrane in Example 1;

[0036] Figure 7 shows the microstructure of the cross-section of the microporous hollow fiber membrane formed by the casting solution 1 in Example 2.

[0037] Explanation of reference numerals in the attached diagram: 1-Three-channel spinneret, 2-Inner layer channel, 3-Middle layer channel, 4-Outer layer channel, 5-Air gap section, 6-Hollow fiber nascent membrane filament, 7-Coagulation bath. Detailed Implementation

[0038] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0039] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0040] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0041] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0042] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight.

[0044] The following specific embodiments further illustrate a microporous hollow fiber membrane, its preparation method, and its application provided in this application.

[0045] Currently available virus filtration membranes, such as the hollow fiber membrane for biopharmaceutical clarification by Asahi Kasei (CN200980137972), involve adding different concentrations of hydrophilic additives to different regions along the membrane thickness direction, resulting in a hollow fiber membrane with progressively increased hydrophilicity from one side to the other, and the membrane having a gradient pore size structure (the outer periphery is the region with the smallest pore size). However, firstly, the inner peripheral region near the inner surface of the membrane in this patent has low hydrophilicity. Although the pore size of the inner peripheral region is large, the monoclonal antibodies and aggregates to be recovered in the filtration solution will still be adsorbed. The overall hydrophilicity of the membrane is more beneficial to the application. The beneficial effect of this patent is still reflected in the size sieving effect of the filtered material by the gradient pore size. Secondly, the patent does not specify the formation method of the surface gradient pore size. According to the invention content of the patent, the membrane is a hollow fiber membrane prepared by non-solvent phase separation (NIPS). When the membrane thickness is 350-800 μm as described, the thickness is very large for hollow fiber membranes prepared by NIPS. Even if the proportion of hydrophilic components gradually increases from the inside to the outside, the pore size range of the middle region of the membrane in the actual membrane structure generated during the phase separation and solidification process may not necessarily connect the pore size of the inner and outer peripheral regions to form a gradient pore size. Thirdly, in the NIPS molding process, the concentration of good solvent in the internal coagulation bath is more than 85% by weight. The membrane fibers are not easy to solidify and form during the spinning process, making it difficult to smoothly draw and collect the fibers.

[0046] Therefore, the present invention provides a method for preparing the aforementioned membrane that can be used to filter viruses. This method utilizes thermally induced phase separation to prepare the membrane. The phase separation driving force comes from the decrease in temperature, rather than phase separation caused by solvent exchange (non-solvent-induced phase separation membrane preparation). Therefore, when preparing gradient pore membranes, the wall thickness is not limited, and gradient pore membranes with large wall thicknesses can be prepared. Hollow fiber membranes are prepared using a three-channel spray plate. By selecting the casting solution formula and core solution in the three channels and coordinating various process parameters, the membrane structure can be precisely controlled.

[0047] The microporous hollow fiber membrane of this application was characterized using the following methods:

[0048] Bubble point test:

[0049] Using a bubble pressure method pore size analysis device, the bubble point pressure and average pore size of the hollow fiber membrane were measured by using the internal pressure method and displacing the n-butanol in the pores of the hollow fiber membrane with saturated n-butanol. A certain pressure increase rate, pressure test upper limit, and weight stabilization time were set.

[0050] Pure water flux test:

[0051] Using dead-end filtration, with the inlet pressure of pure water at 25℃ set at 4 bar, the pure water permeation rate per unit time, unit pressure, and unit membrane area was measured. The pure water flux was calculated using the following formula: Pure water flux (L / m²) 2•bar·h) = Pure water permeate flow rate / Effective membrane area / Filtration time / Feed pressure

[0052] Colloidal gold retention test:

[0053] Referring to the test method in patent CN201780009989, colloidal gold solutions at 70nm, 50nm, 30nm, and 20nm were prepared. The colloidal gold solutions were diluted with injectable distilled water, polyoxyethylene-naphthyl ether (1.59 vol%), and poly(4-styrenesulfonate sodium) (0.20 vol%) until the absorbance of the diluted colloidal gold solution at the maximum absorption wavelength was measured to be 0.25 using a UV-Vis spectrophotometer. An effective area of ​​10 cm² was used. 2 The membrane was used to filter 40 mL of colloidal gold solutions of various sizes at a pressure of 196 kPa. The filters were applied sequentially from large to small particle sizes. The absorbance of the filtrate at the maximum absorption wavelength was measured using the aforementioned UV spectrophotometer and denoted as 'a'. The logarithmic removal rate (LRV) of the membrane for colloidal gold was calculated using the following formula: LRV = log 10 (0.25 / a)

[0054] The cross-section of the hollow fiber membrane that has captured colloidal gold particles was visually inspected using an optical microscope. The relative positions of the captured colloidal gold particles in the cross-section were determined. The captured parts of the colloidal gold are shown in Schematic 1. It can be seen that the distance from the center of the circle to the position where colloidal gold of the same size is trapped on the circumference is close. That is, the pore size is uniform under the same radius on the circumference. In practical applications, the virus is not easy to leak.

[0055] Average pore size test of the membranes formed by casting solutions 1 and 2:

[0056] Hollow fiber membrane 1 and hollow fiber membrane 2 were prepared using casting solution 1 and casting solution 2, respectively. The microstructure of the inner and outer surfaces of the membrane was adjusted to be close to the forming structure of the corresponding casting solution position. The average pore size of the membranes formed by the two casting solutions was tested. The average pore size of membrane 1 was 0.045-0.05 μm, and the average pore size of membrane 2 was 0.019-0.022 μm.

[0057] Methods for determining melting point:

[0058] The melting point T of the polyvinylidene fluoride of this invention mp The compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d1 has a melting point T. mp-d1 The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d2 mp-d2 And the melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% core liquid. mp-b The melting point was determined using differential scanning calorimetry (DSC) at a cooling rate of 5 °C / min.

[0059] Example 1

[0060] Using a screw extruder or a high-temperature stirred tank, 30 wt% polyvinylidene fluoride and 70 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 45 wt% polyvinylidene fluoride and 55 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0061] Casting solution 1, casting solution 2, and dimethyl sebacate (130°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. As shown in Figure 2, the extruded liquid enters a coagulation bath at 20°C after passing through a 100mm air gap section to cool and form hollow fibers.

[0062] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0063] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0064] The microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 1 is shown in Figure 3, and the microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 2 is shown in Figure 4.

[0065] The microstructure of the inner surface of the prepared microporous hollow fiber membrane is shown in Figure 5, and the microstructure of the outer surface is shown in Figure 6. The inner diameter of the microporous hollow fiber membrane is 400 μm, the wall thickness is 120 μm, and the bubble point measured by the liquid-liquid method is 1.8 bar. The pure water flux of the microporous hollow fiber membrane is 38 L / (m³). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 1.4, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 1.2. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 38 L / (m²). 2 ·h·bar).

[0066] Example 2

[0067] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% diphenyl carbonate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0068] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then fed to a three-channel spinneret at 225°C for extrusion. The extruded liquid passes through a 100mm air gap section and then enters a coagulation bath at 20°C to cool and form hollow fibers.

[0069] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0070] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0071] The microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 1 is shown in Figure 7, and the microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 2 is shown in Figure 4. The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 2.3 bar as measured by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 33 L / (m²). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 2, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 2. Membrane slices filtered through the aforementioned four particle sizes were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 33 L / (m²). 2 ·h·bar).

[0072] Example 3

[0073] Using a screw extruder or a high-temperature stirred tank, 30 wt% polyvinylidene fluoride and 70 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dibutyl sebacate were mixed evenly at 220°C to obtain casting solution 2.

[0074] Casting solution 1, casting solution 2, and diethyl phthalate at 120°C as the core liquid are metered by a melt metering pump and then fed to a three-channel spinneret at 225°C for extrusion. The extruded liquid passes through a 100mm air gap section and then enters a coagulation bath at 20°C to cool and form hollow fibers.

[0075] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0076] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0077] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 2.2 bar measured by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 34 L / (m²). 2 (·h·bar). The hollow fiber membrane showed a logarithmic removal rate of 6 for colloidal gold with a diameter of 70 nm, 6 for 50 nm, 2 for 30 nm, and 1.8 for 20 nm. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were examined using an optical microscope. The particle retention area conformed to the range shown in Figure 1, with no significant shift. The pure water flux of the membrane after retaining colloidal gold was tested to be 34 L / (m²). 2 ·h·bar).

[0078] Example 4

[0079] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% diphenyl carbonate were stirred and mixed evenly at 210°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 210°C to obtain casting solution 2.

[0080] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. The extruded liquid passes through a 70mm air gap section and then enters a coagulation bath at 20°C to cool and form hollow fibers.

[0081] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0082] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0083] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 2.6 bar measured by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 27 L / (m²). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 2, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 2. Membrane slices filtered through the aforementioned four particle sizes were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 26 L / (m²). 2 ·h·bar).

[0084] Example 5

[0085] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dibutyl sebacate were mixed evenly at 220°C to obtain casting solution 2.

[0086] Casting solution 1, casting solution 2, and diethyl phthalate at 120°C as the core liquid are metered by a melt metering pump and then fed to a three-channel spinneret at 200°C for extrusion. The extruded liquid passes through a 100mm air gap section and then enters a coagulation bath at 20°C to cool and form hollow fibers.

[0087] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0088] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0089] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 3 bar as determined by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 20 L / (m²). 2 (·h·bar). The hollow fiber membrane showed a logarithmic removal rate of 6 for colloidal gold with a diameter of 70 nm, 6 for 50 nm, 2 for 30 nm, and 1.8 for 20 nm. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were examined using an optical microscope. The particle retention area conformed to the range shown in Figure 1, with no significant shift. The pure water flux of the membrane after retaining colloidal gold was tested to be 16 L / (m²). 2·h·bar).

[0090] Example 6

[0091] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0092] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. As shown in Figure 2, the extruded liquid enters a coagulation bath at 20°C after passing through a 100mm air gap section to cool and form hollow fibers.

[0093] The flow rates of casting solution 1 and casting solution 2 are 9.3 mL / min and 11.9 mL / min, respectively, the flow rate of core solution is 13.5 mL / min, and the spinning rate is 60 m / min.

[0094] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0095] The microporous hollow fiber membrane has an inner diameter of 400 μm and a wall thickness of 120 μm. Its bubble point, determined by the liquid-liquid method, is 2.3 bar. The pure water flux of the microporous hollow fiber membrane is 32 L / (m³). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 2, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 1.8. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant shift. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 31 L / (m²). 2 ·h·bar).

[0096] Example 7

[0097] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0098] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. As shown in Figure 2, the extruded liquid enters a coagulation bath at 20°C after passing through a 100mm air gap section to cool and form hollow fibers.

[0099] The flow rates of casting solution 1 and casting solution 2 are 4.7 mL / min and 5.9 mL / min, respectively, the flow rate of core solution is 6.75 mL / min, and the spinning rate is 30 m / min.

[0100] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0101] The microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 1 is shown in Figure 3, and the microstructure of the cross-section of the microporous hollow fiber membrane formed by casting solution 2 is shown in Figure 4.

[0102] The microstructure of the inner surface of the prepared microporous hollow fiber membrane is shown in Figure 5, and the microstructure of the outer surface is shown in Figure 6. The inner diameter of the microporous hollow fiber membrane is 400 μm, the wall thickness is 120 μm, and the bubble point measured by the liquid-liquid method is 2 bar. The pure water flux of the microporous hollow fiber membrane is 36 L / (m³). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 2, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 1.8. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 36 L / (m²). 2 ·h·bar).

[0103] Example 8

[0104] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0105] Casting solution 1, casting solution 2, and dimethyl sebacate (60°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. The extruded liquid passes through a 100mm air gap section and then enters a coagulation bath at 20°C to cool and form hollow fibers.

[0106] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0107] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0108] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 2.4 bar measured by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 29 L / (m²). 2 (·h·bar). The hollow fiber membrane showed a logarithmic removal rate of 6 for colloidal gold with a diameter of 70 nm, 6 for 50 nm, 2 for 30 nm, and 1.8 for 20 nm. Membrane slices filtered through the aforementioned four particle sizes of colloidal gold solutions were examined using an optical microscope. The particle retention area conformed to the range shown in Figure 1, with no significant shift. The pure water flux of the membrane after retaining colloidal gold was tested to be 26 L / (m²). 2 ·h·bar).

[0109] Example 9

[0110] Using a screw extruder or a high-temperature stirred tank, 33 wt% polyvinylidene fluoride and 67 wt% tributyl citrate were stirred and mixed evenly at 230°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 48 wt% polyvinylidene fluoride and 52 wt% dicyclohexyl phthalate were mixed evenly at 230°C to obtain casting solution 2.

[0111] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then fed to a three-channel spinneret at 225°C for extrusion. The extruded liquid passes through a 100mm air gap section and then enters a coagulation bath at 50°C to cool and form hollow fibers.

[0112] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0113] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0114] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 2.2 bar measured by the liquid-liquid method. The pure water flux of the hollow fiber membrane is 58 L / (m²). 2(·h·bar). The hollow fiber membrane showed a logarithmic removal rate of 5 for colloidal gold with a diameter of 70 nm, 5 for 50 nm, 1.5 for 30 nm, and 1.2 for 20 nm. Membrane slices were prepared after filtering colloidal gold solutions of the aforementioned four particle sizes. Optical microscopy revealed the particle retention area, which conformed to the range shown in Figure 1, without significant shift. The pure water flux of the membrane after retaining colloidal gold was tested to be 50 L / (m²). 2 ·h·bar).

[0115] Example 10

[0116] Using a screw extruder or a high-temperature stirred tank, 40 wt% polyvinylidene fluoride and 60 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 50 wt% polyvinylidene fluoride and 50 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0117] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. As shown in Figure 2, the extruded liquid enters a coagulation bath at 20°C after passing through a 100mm air gap section to cool and form hollow fibers.

[0118] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0119] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0120] The microporous hollow fiber membrane has an inner diameter of 400 μm and a wall thickness of 120 μm. Its bubble point, determined by the liquid-liquid method, is 2.6 bar. The pure water flux of the microporous hollow fiber membrane is 30 L / (m²). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 6, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 3.5, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 2. Membrane slices filtered through the aforementioned four particle sizes were observed under an optical microscope, and the particle retention area conformed to the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 27 L / (m²). 2 ·h·bar).

[0121] Example 11

[0122] Using a screw extruder or a high-temperature stirred tank, 28 wt% polyvinylidene fluoride and 72 wt% tributyl citrate were stirred and mixed evenly at 220°C to obtain casting solution 1; using a screw extruder or a high-temperature stirred tank, 43 wt% polyvinylidene fluoride and 67 wt% dicyclohexyl phthalate were mixed evenly at 220°C to obtain casting solution 2.

[0123] Casting solution 1, casting solution 2, and dimethyl sebacate (120°C) used as the core liquid are metered by a melt metering pump and then supplied to a three-channel spinneret at 225°C for extrusion. As shown in Figure 2, the extruded liquid enters a coagulation bath at 20°C after passing through a 100mm air gap section to cool and form hollow fibers.

[0124] The flow rates of casting solution 1 and casting solution 2 are 6.2 mL / min and 7.9 mL / min, respectively, the flow rate of core solution is 9 mL / min, and the spinning rate is 40 m / min.

[0125] The residual chemical reagents in the hollow fiber were fully extracted using ethanol and then dried to obtain a microporous hollow fiber membrane.

[0126] The microporous hollow fiber membrane has an inner diameter of 400 μm and a wall thickness of 120 μm. Its bubble point, determined by the liquid-liquid method, is 1.8 bar. The pure water flux of the microporous hollow fiber membrane is 49 L / (m³). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70 nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50 nm was 5, the logarithmic removal rate of colloidal gold with a diameter of 30 nm was 1.2, and the logarithmic removal rate of colloidal gold with a diameter of 20 nm was 1. Membrane slices filtered through the aforementioned four particle sizes were observed by optical microscopy, and the particle retention area was consistent with the range shown in Figure 1, without significant deviation. The pure water flux of the microporous hollow fiber membrane after retaining colloidal gold was tested to be 49 L / (m). 2 ·h·bar).

[0127] Comparative Example 1

[0128] Based on Example 1, hollow fiber membranes were prepared using only core liquid and casting liquid 2, without using casting liquid 1.

[0129] The prepared hollow fiber membrane has an inner diameter of 400 μm and a wall thickness of 60 μm. Its bubble point, determined by the liquid-liquid method, is 2.2 bar. The pure water flux of the central fiber membrane is 40 L / (m²). 2 (·h·bar). Its logarithmic removal rate for colloidal gold is basically at the same level, but the pure water flux of the membrane after removing colloidal gold is only 12L / (m). 2 ·h·bar).

[0130] Comparative Example 2

[0131] Based on Example 2, hollow fiber membranes were prepared using only core liquid and casting liquid 2, without using casting liquid 1.

[0132] The prepared hollow fiber membrane has an inner diameter of 400 μm and a wall thickness of 60 μm. Its bubble point, determined by the liquid-liquid method, is 2.4 bar. The pure water flux of the central fiber membrane is 35 L / (m²). 2 (·h·bar). Its logarithmic removal rate for colloidal gold is basically at the same level, but the pure water flux of the membrane after removing colloidal gold is only 7L / (m). 2 ·h·bar).

[0133] Comparative Example 3

[0134] Based on Example 10, the casting solution consisted of 70 wt% polyvinylidene fluoride and 30 wt% dicyclohexyl phthalate, with all other conditions remaining the same.

[0135] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 4.7 bar measured by the liquid-liquid method. The pure water flux of the central fiber membrane is 12 L / (m²). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70nm by the microporous hollow fiber membrane was 6, the logarithmic removal rate of colloidal gold with a diameter of 50nm was 5, the logarithmic removal rate of colloidal gold with a diameter of 30nm was 4, and the logarithmic removal rate of colloidal gold with a diameter of 20nm was 3. However, the pure water flux of the membrane after the colloidal gold was retained was only 4L / (m). 2 ·h·bar).

[0136] Comparative Example 4

[0137] Based on Example 11, the casting solution component 1 consisted of 22 wt% polyvinylidene fluoride and 82 wt% tributyl citrate, with other conditions remaining the same.

[0138] The prepared hollow fiber membrane has an inner diameter of 400 μm, a wall thickness of 120 μm, and a bubble point of 1.4 bar measured by the liquid-liquid method. The pure water flux of the central fiber membrane is 65 L / (m²). 2 (·h·bar). The logarithmic removal rate of colloidal gold with a diameter of 70nm by the microporous hollow fiber membrane was 4, the logarithmic removal rate of colloidal gold with a diameter of 50nm was 3, the logarithmic removal rate of colloidal gold with a diameter of 30nm was 0.9, and the logarithmic removal rate of colloidal gold with a diameter of 20nm was <1. However, the pure water flux of the membrane after the colloidal gold was retained was only 65L / (m). 2 ·h·bar).

[0139] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A microporous hollow fiber membrane, wherein, It has an inner surface that contacts the protein-containing solution and an outer surface that discharges the filtrate; The cross-section from the inner surface to the outer surface has a gradient pore size structure with an average pore size varying from 70 to 20 nm, and it has a double continuous network structure; the pores on the inner surface of the hollow fiber membrane are micropores of 0.2 to 3 μm, and the pores on the outer surface are micropores of 0.01 to 0.1 μm; the inner diameter of the membrane is 100 to 800 μm, and the wall thickness is 60 to 500 μm.

2. The microporous hollow fiber membrane according to claim 1, wherein, The material of the microporous hollow fiber membrane is polyvinylidene fluoride.

3. The microporous hollow fiber membrane according to claim 1, wherein, The pure water flux of the microporous hollow fiber membrane is 20–60 L / (m²). 2 The bubble point range of the microporous hollow fiber membrane is 1.7 to 3 bar.

4. A method for preparing the microporous hollow fiber membrane according to any one of claims 1 to 3, wherein, include: Step 1: The core liquid, casting liquid 1, and casting liquid 2 are fed into a three-channel spinneret. The temperatures of the core liquid, casting liquid 1, and casting liquid 2, the spinning temperature, flow rate, and spinning speed of the spinneret are controlled to extrude hollow fiber nascent membrane filaments. The inner channel of the three-channel spinneret is the core liquid channel, the middle channel is the casting liquid 1 channel, and the outer channel is the casting liquid 2 channel. Step 2: The hollow fiber nascent membrane filaments pass through the air gap section and enter the coagulation bath to solidify and form a membrane. Then, they are immersed in the extractant for extraction and dried to obtain a microporous hollow fiber membrane. The core liquid is a sebacic acid ester, phthalic acid ester, adipate ester, citrate ester, or phosphate ester; the casting liquid 1 consists of 25-40 wt% polyvinylidene fluoride and 60-75 wt% solvent d1, and the casting liquid 2 consists of 40-60 wt% polyvinylidene fluoride and 40-60 wt% solvent d2.

5. The method for preparing a microporous hollow fiber membrane according to claim 4, wherein, The solvents d1 and d2 are sebacic acid esters, phthalic acid esters, adipate esters, citrate esters, or phosphate esters.

6. The method for preparing a microporous hollow fiber membrane according to claim 4, wherein, The core fluid, solvent d1, and solvent d2 are at the melting point T of polyvinylidene fluoride. m p The above are ester-based organic solvents that form homogeneous solutions with polyvinylidene fluoride.

7. The method for preparing a microporous hollow fiber membrane according to claim 6, wherein, The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d1 m p-d1 Satisfying 10℃ < T m p -T m p-d1 <20℃; The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% solvent d2 m p-d2 Satisfying 2℃ < T m p -T m p-d2 <8℃; The melting point T of the compound formed by 50 wt% polyvinylidene fluoride and 50 wt% core liquid b m p-b Satisfying 30℃ < T m p -T m p-b <100℃.

8. The method for preparing a microporous hollow fiber membrane according to claim 7, wherein, The T m p-b T m p-d1 and T m p-d2 Satisfy T m p-d2 -T m p-d1 <8℃, 10℃ <T m p-d1 -T m p-b <40℃.

9. The method for preparing a microporous hollow fiber membrane according to claim 4, wherein, The core liquid temperature range is 60–170℃, and the core liquid flow rate range is 3–30 mL / min; the casting liquid 1 and casting liquid 2 have a temperature range of 180–240℃, and the casting liquid 1 and casting liquid 2 have a flow rate range of 2–15 mL / min; the spinning temperature is 180–240℃.

10. The method for preparing a microporous hollow fiber membrane according to claim 4, wherein, The coagulation bath is an organic solvent or water that is not miscible with polyvinylidene fluoride below 50°C; the temperature range of the coagulation bath is 10–50°C; the length range of the air gap section is 10–150 mm; and the spinning rate range is 10–100 m / min.

11. An application of the microporous hollow fiber membrane according to any one of claims 1 to 3, wherein, The microporous hollow fiber membrane is used for virus filtration in downstream processes of bioproducts.

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