Application of a hydrophobic polyethersulfone microporous membrane in air filtration

Abstract

The present invention belongs to the technical field of air filtration, and provides an application of a hydrophobic polyethersulfone microporous membrane in air filtration, including a hydrophobic polyethersulfone microporous membrane as a filter membrane of a sterile respirator; the hydrophobic polyethersulfone microporous membrane is prepared by the following method: preparing a modification liquid: the modification liquid includes the following raw materials in mass fractions: 5 to 20 parts of a modifier, 30 to 94.5 parts of a diluent, and 0.5 to 3 parts of an additive, wherein the modifier is one or more of a C6 waterproofing agent, a C8 waterproofing agent, a polyurethane fluorine-free waterproofing agent, and an acrylic fluorine-free waterproofing agent; using a hydrophilic polyethersulfone membrane as a base membrane, soaking the base membrane in the modification liquid, and then drying to obtain a hydrophobic polyethersulfone microporous membrane. The hydrophobic polyethersulfone microporous membrane of the present invention is the best choice material for a respirator in a filter because of its excellent air permeability and hydrophobicity and good gamma irradiation tolerance.

Description

Technical Field

[0001] The present application relates to the technical field of air filtration, and in particular to the application of a hydrophobic polyethersulfone microporous membrane in air filtration. Background Art

[0002] Polyethersulfone (PES) microporous membrane is a high-performance separation membrane with excellent chemical stability and mechanical strength. It can be easily prepared by non-solvent induced phase separation (NIPS) method. Hydrophobic PES membrane has better air permeability than PVDF membrane, and its inherent strong gamma resistance is more stable than PTFE membrane. It is also resistant to high temperature and high pressure. It is an efficient membrane for filtration and ventilation applications.

[0003] At present, in the medical field, polyethersulfone filter membranes are often used in clean room and sterile room air purification systems to filter out microorganisms and dust particles in the air to ensure the cleanliness of the working environment. In addition, due to its excellent filtration efficiency and service life, polyethersulfone filter membranes can also be used in the field of air filtration to filter out smaller particles and effectively purify the air. However, the filtration efficiency of polyethersulfone filter membranes is not very ideal.

[0004] When preparing polyethersulfone membranes, hydrophilic polymers such as PVP and PEG are often added as pore-forming agents, which results in insufficient hydrophobicity of the prepared polyethersulfone membranes, limiting their application in the field of air filtration.

[0005] Based on this, existing research, such as the patent with publication number CN103495352A, discloses a method for preparing a modified polyethersulfone-based hydrophobic membrane for a gas-liquid membrane contactor. The modified polyethersulfone-based hydrophobic membrane prepared by the method can be used for membrane contactor processes such as SO2 removal, membrane seawater desulfurization and denitrification, acid gas removal, volatile organic matter removal, and air dehumidification. However, the modified polyethersulfone-based hydrophobic membrane cannot clearly show its sterilization and ventilation performance, and cannot guarantee that it has a good filtering effect when used in air filtration.

[0006] For example, Xing Wei et al. fluorinated PES flat membranes and hollow fiber membranes by CF4 plasma grafting to transform hydrophilic membranes into hydrophobic membranes. However, this hydrophobic membrane is suitable for membrane distillation rather than air filtration.

[0007] Filtration is an ideal method for liquid clarification and sterilization. It can effectively remove various microorganisms and particles through membrane interception without affecting the effective ingredients due to adsorption or decomposition. Some medical containers, bioreactors, cell culture flasks and bottles, fermentation tanks and medical equipment piping systems require aseptic ventilation. Therefore, it is necessary to develop hydrophobic polyethersulfone microporous membranes for removing particulate matter and bacteria in air or other gases. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, the present invention provides an application of a hydrophobic polyethersulfone microporous membrane in air filtration to solve the problems that the existing polyethersulfone filter membrane has poor filtering effect when used for air filtration and cannot achieve rapid air filtration, sterilization and ventilation.

[0009] To achieve the above and related purposes, the present invention provides an application of a hydrophobic polyethersulfone microporous membrane in air filtration, comprising: the hydrophobic polyethersulfone microporous membrane is used as a filter membrane of a sterile respirator; the hydrophobic polyethersulfone microporous membrane is prepared by the following method:

[0010] (1) Preparation of modifying liquid: The modifying liquid includes the following raw materials in parts by weight:

[0011] 5 to 20 parts of a modifier, 30 to 94.5 parts of a diluent, and 0.5 to 3 parts of an additive, wherein the modifier is one or more of a C6 waterproofing agent, a C8 waterproofing agent, a polyurethane fluorine-free waterproofing agent, and an acrylic fluorine-free waterproofing agent;

[0012] (2) A hydrophilic polyethersulfone membrane is used as a base membrane, the base membrane is immersed in a modification liquid, and then dried to obtain a hydrophobic polyethersulfone microporous membrane.

[0013] In one embodiment of the present application, the sterile respirator is a respirator in a bioreactor.

[0014] In one embodiment of the present application, the additive in step (1) is one or more of formic acid, acetic acid, and hydrochloric acid.

[0015] In one embodiment of the present application, the pore size of the base film in step (2) is 0.05 μm to 5 μm.

[0016] In one embodiment of the present application, step (2) further includes: soaking the base film in the modifying liquid in one of the following two ways: placing the base film in the modifying liquid for soaking; or transferring the base film into the modifying liquid for soaking.

[0017] In one embodiment of the present application, the soaking time is 5 to 8 minutes.

[0018] In one embodiment of the present application, when the base film is conveyed into the modifying liquid for immersion, the conveying speed of the base film is 2 m / min to 2.5 m / min.

[0019] In one embodiment of the present application, the base film is immersed in the modifying liquid at 20-30°C.

[0020] In one embodiment of the present application, the drying temperature in step (2) is 150-160°C.

[0021] In one embodiment of the present application, the diluent in step (1) is pure water.

[0022] In one embodiment of the present application, the water contact angle of the hydrophobic polyethersulfone microporous membrane is greater than 100°.

[0023] The beneficial technical effects of the present invention are:

[0024] The hydrophobic polyethersulfone microporous membrane prepared by the present invention using a simple hydrophobic modification method has low cost, excellent air permeability and hydrophobicity, and good gamma irradiation tolerance. When the hydrophobic polyethersulfone microporous membrane of the present invention is applied to air filtration and used as a filter membrane of a respirator, it can be used for rapid air filtration, sterilization and ventilation, and also has waterproof, moisture permeable and breathable effects, and is used to prevent liquid penetration or condensed water clogging.

[0025] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0027] Figure 1 A schematic diagram of the device used for continuous production of the hydrophobic modification method of this application;

[0028] Figure 2 The electron microscope scanning images of the control group of Example 1 before and after modification;

[0029] Figure 3 The electron microscope scanning images of the polyethersulfone membrane before and after modification of Example 1;

[0030] Figure 4 This is a diagram of the cell culture experiment results in Example 5.

[0031] Reference numerals

[0032] 1: Unwinding mechanism; 2: Winding mechanism; 3: Modified liquid pool; 4: Hot wheel; 5: Rewinding mechanism; 6: Base film. DETAILED DESCRIPTION

[0033] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as the general understanding of a person of ordinary skill in the art to which the present invention belongs. It should be understood that certain features of the present invention (described in the context of separate embodiments for clarity) may also be provided in combination in a single embodiment. On the contrary, multiple features of the present invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or in any other described embodiment of the present invention when appropriate. Certain features described in the context of various embodiments will not be considered as essential features of those embodiments unless the embodiment is inoperable without those elements. The present invention is further described below by specific specific examples, but it should be noted that the specific process conditions and results described in the embodiments of the present invention are only used to illustrate the present invention, and the protection scope of the present invention cannot be limited thereto. All equivalent changes or modifications made according to the spirit and essence of the present invention should be included in the protection scope of the present invention.

[0034] First of all, it should be noted that the hydrophilic polyethersulfone membranes used in the examples and comparative examples of the present application are self-produced membranes. The membrane used in the control group is a commercially available polyethersulfone membrane.

[0035] The present invention provides an application of a hydrophobic polyethersulfone microporous membrane in air filtration, comprising: the hydrophobic polyethersulfone microporous membrane is used as a filter membrane of a sterile respirator; the hydrophobic polyethersulfone microporous membrane is prepared by the following method:

[0036] (1) Preparation of modifying liquid: The modifying liquid includes the following raw materials in parts by weight:

[0037] 5 to 20 parts of modifier, 30 to 94.5 parts of diluent, and 0.5 to 3 parts of additive, wherein the modifier is one or more of C6 waterproofing agent, C8 waterproofing agent, polyurethane fluorine-free waterproofing agent, and acrylic fluorine-free waterproofing agent; the additive is one or more of formic acid, acetic acid, and hydrochloric acid; and the diluent is pure water.

[0038] The preparation method of the modified liquid is as follows:

[0039] The modifier is diluted according to the above ratio, a certain amount of additives is added, and the mixture is stirred evenly at 25-60° C. to prepare a modified liquid.

[0040] (2) A hydrophilic polyethersulfone membrane is used as a base membrane, the base membrane is immersed in a modification liquid, and then dried to obtain a hydrophobic polyethersulfone microporous membrane.

[0041] Furthermore, the membrane pore diameter of the base membrane is 0.05 μm to 5 μm.

[0042] Furthermore, the method of immersing the base film in the modifying liquid is selected from any one of the following two methods: placing the base film statically in the modifying liquid for immersion; or transferring the base film into the modifying liquid for immersion.

[0043] Furthermore, the soaking time is 5 to 8 minutes.

[0044] Furthermore, the conveying speed of the base film is 2 m / min to 2.5 m / min.

[0045] Furthermore, the base film is immersed in the modifying liquid at 20 to 30°C.

[0046] Furthermore, the drying temperature is 150-160°C.

[0047] Further, the hydrophobic modification method of the present application is used for continuous production as follows Figure 1 The device shown. Specifically, the device includes an unwinding mechanism 1, a winding mechanism 2, a modified liquid pool 3, a hot wheel 4 and a winding mechanism 5 which are arranged in sequence according to the production order. When the device of the present application is used for continuous production, the base film 6 is placed on the unwinding mechanism 1, and the winding mechanism 2 is started at room temperature of 20 to 30°C to allow the base film 6 to pass through the modified liquid pool 3 containing the modified liquid at a uniform speed of 2 to 2.5 m / min, preferably 2 m / min, and ensure that the base film 6 is evenly soaked. The base film 6 after soaking treatment is introduced into the hot wheel 4, dried at 150 to 160°C, and then introduced into the winding mechanism 5 to obtain a hydrophobic polyethersulfone microporous membrane.

[0048] Further, the sterile respirator is a respirator in a bioreactor.

[0049] Furthermore, the water contact angle of the polyethersulfone microporous membrane is greater than 100°.

[0050] The present invention is described in detail below by specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0051] Example 1

[0052] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 30°C until they become clear:

[0053] 10 parts of C6 waterproofing agent, 87 parts of pure water, and 3 parts of acetic acid.

[0054] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.22 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 5 minutes, taken out, and dried at 155°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0055] (3) In this example, a commercially available hydrophilic polyethersulfone membrane was used as the base membrane, and the above steps (1) and (2) were carried out as a control group to obtain a modified polyethersulfone microporous membrane.

[0056] Example 2

[0057] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 25°C until they become clear:

[0058] 5 parts of polyurethane non-fluorine waterproofing agent, 94 parts of pure water, and 1 part of acetic acid.

[0059] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 6 minutes, taken out, and dried at 160°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0060] (3) In this example, a commercially available hydrophilic polyethersulfone membrane was used as the base membrane, and the above steps (1) and (2) were carried out as a control group to obtain a modified polyethersulfone microporous membrane.

[0061] Example 3

[0062] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 25°C until they become clear:

[0063] 5 parts of C6 waterproofing agent, 92 parts of pure water, and 3 parts of acetic acid.

[0064] (2) A hydrophilic polyethersulfone membrane with a pore size of 1.2 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 5 minutes, taken out, and dried at 155°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0065] Comparative Example 1

[0066] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 25°C until they become clear:

[0067] 12 parts of polyurethane non-fluorine waterproofing agent, 78 parts of pure water, and 10 parts of acetic acid.

[0068] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 6 minutes, taken out, and dried at 160°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0069] Comparative Example 2

[0070] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 25°C until they become clear:

[0071] 20 parts of polyurethane non-fluorine waterproofing agent, 70 parts of pure water, and 10 parts of acetic acid.

[0072] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 6 minutes, taken out, and dried at 160°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0073] Comparative Example 3

[0074] (1) Preparation of modified liquid: Mix the following raw materials in parts by weight and stir at 25°C until they become clear:

[0075] 3 parts of C6 waterproofing agent, 95 parts of pure water, and 2 parts of acetic acid.

[0076] (2) A hydrophilic polyethersulfone membrane with a pore size of 1.2 μm was used as the base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in the modification liquid at a transport speed of 2 m / min at 25°C for 5 minutes, taken out, and dried at 155°C for 5 minutes to obtain a hydrophobic polyethersulfone microporous membrane.

[0077] Example 4

[0078] Two 2L glass reactors were used for cell culture experiments. The first reactor used a disc filter, which used the hydrophobic polyethersulfone microporous membrane in Example 1 as the filter membrane of the respirator; the second reactor used a commercially available imported polyethersulfone disc filter product as the respirator. The cell culture conditions of the two reactors were kept consistent, and the cell results were observed for 10 days. The cell culture results are shown in Figure 2. Figure 4 shown.

[0079] Performance Testing

[0080] Physical properties: The physical properties of each polyethersulfone microporous membrane in Examples 1 to 3 and Comparative Examples 1 to 3 before and after modification were tested. The test results are shown in Table 1.

[0081] EDS energy spectrum analysis: EDS energy spectrum analysis was performed on the surface of the self-produced polyethersulfone microporous membrane after hydrophobic modification in Example 1 and the polyethersulfone microporous membrane of the control group. The analysis results are shown in Table 2 and Table 3.

[0082] Microscopic morphology: Using a scanning electron microscope, the microscopic morphology of the self-produced polyethersulfone membrane of Example 1 and the polyethersulfone membrane of the control group before and after hydrophobic modification was observed, and their electron microscope scanning images were obtained, as shown in FIG. Figure 2 , Figure 3 shown.

[0083] Gamma irradiation: The self-produced polyethersulfone microporous membrane after hydrophobic modification in Example 1 and the polyethersulfone microporous membrane of the control group were subjected to gamma irradiation, and the physical property data of the membranes before and after gamma irradiation sterilization were measured. The measurement results are shown in Table 4.

[0084] Bacterial challenge: The self-produced polyethersulfone microporous membrane after hydrophobic modification in Example 1 and the control group polyethersulfone microporous membrane after gamma irradiation sterilization were subjected to bacterial challenge experiments. The challenge results are shown in Table 5.

[0085] The bacterial challenge experiment method is as follows:

[0086] 1. Place 1L of 75% ethanol in the interception device, open the valve, and disinfect the sample inlet line. After disinfection, replace with 1L of sterile water and rinse the sample inlet line. Take four sets of membrane disks, the first three sets are set as test groups, the upper membrane is the membrane to be tested, and the lower layer is the analytical filter membrane. The fourth set is set as the positive group, and both the upper and lower membranes are analytical membranes. A PET support layer needs to be placed under each membrane.

[0087] 2. Negative control group: 1L of sterile water is placed in the interception device and passed through the filter membrane to be tested and its downstream pipeline. After the sterile water fills the device, it is collected through a microporous membrane with a pore size of 0.45μm (negative control collection membrane). The above negative control membrane is transferred to the TSA plate, cultured at 30±2℃ for 3-7 days, and observed and counted.

[0088] 3. Experimental group and positive group: Load the challenge liquid into the interception device and filter it through the filter membrane to be tested and its downstream pipeline at a pressure difference of about 0.2Mpa and a flow rate of 30-40mL / min. After the challenge liquid is filtered, remove the lower membrane and transfer it to the TSA plate, culture it at 30±2℃ for 3-7 days, observe and count.

[0089] The experimental data and analysis are as follows:

[0090] Table 1 Physical properties of polyethersulfone microporous membranes before and after modification in various embodiments and comparative examples

[0091]

[0092]

[0093] As can be seen from Table 1, the hydrophobic polyethersulfone microporous membranes prepared in the examples of the present application have water contact angles greater than 100° after modification, high water pressure resistance, and excellent water repellency; and the difference in air flow rate between the membranes before and after modification is small, and the membranes have good air permeability.

[0094] In addition, judging from the physical properties of the self-produced PES membranes of Examples 1 and 2 and the PES membrane of the control group before and after modification, the hydrophobic modification method of the present application is universal and can achieve a good hydrophobic modification effect on hydrophilic polyethersulfone membranes.

[0095] In the modification methods of Comparative Examples 1 to 3, the dosage of each component of the modification liquid exceeds the specified range of the present application, resulting in a significant decrease in the water pressure resistance of the hydrophobic modified polyethersulfone microporous membrane and a shortened service life; and when the hydrophobic polyethersulfone microporous membrane is used for air filtration, its filtration efficiency is low due to its excessively high air flow rate.

[0096] Table 2 Relative element content of the hydrophobically modified polyethersulfone membrane in the control group of Example 1

[0097]

[0098] Table 3 Relative element content of self-produced polyethersulfone membrane after hydrophobic modification in Example 1

[0099]

[0100] It can be seen from Tables 2 and 3 that after modification by the hydrophobic modification method of the present application, fluorine element is added to the surface of the self-produced polyethersulfone microporous membrane and the control group polyethersulfone microporous membrane, which indicates that the C6 waterproofing agent has been combined with the surface of the polyethersulfone microporous membrane, completing the hydrophobic modification of the hydrophilic polyethersulfone membrane.

[0101] like Figure 2 and Figure 3 As shown, from the electron microscope scanning image, whether it is the self-produced PES membrane or the commercially available PES membrane, the hydrophobic polyethersulfone microporous membrane prepared by the hydrophobic modification method of the present application has no change in membrane structure before and after modification, which indicates that the hydrophobic modification method of the present application does not change the main structure of the membrane, but only changes the hydrophilicity of the membrane surface.

[0102] Table 4 Comparison of data before and after gamma irradiation sterilization of hydrophobic polyethersulfone microporous membrane in Example 1

[0103]

[0104] As can be seen from Table 4, the hydrophobic polyethersulfone microporous membrane prepared by the hydrophobic modification method of the present invention does not change in water pressure resistance, air flow rate (air permeability) and bubble point after multiple gamma irradiation sterilization, which indicates that the hydrophobic polyethersulfone microporous membrane of the present invention has excellent gamma irradiation tolerance.

[0105] Table 5 Bacterial challenge results after gamma irradiation sterilization of hydrophobic polyethersulfone microporous membrane

[0106]

[0107]

[0108] It can be seen from Table 5 that the hydrophobic polyethersulfone microporous membrane prepared by the hydrophobic modification method of the present invention can pass the bacterial challenge verification after multiple gamma irradiation sterilization.

[0109] like Figure 4 As shown, the cell culture results of the bioreactor using the hydrophobic polyethersulfone microporous membrane prepared by the present invention as the filter membrane of the sterile respirator and the bioreactor using the commercially available imported polyethersulfone disc filter product as the respirator are consistent in terms of cell proliferation density, cell viability, etc.

[0110] Therefore, the hydrophobic polyethersulfone microporous membrane of the present invention is the best material for the respirator in the filter because of its excellent air permeability and hydrophobicity and good gamma radiation tolerance.

[0111] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. Application of a hydrophobic polyethersulfone microporous membrane in air filtration, characterized in that: The application includes: the hydrophobic polyethersulfone microporous membrane is used as a filter membrane of a sterile respirator; the hydrophobic polyethersulfone microporous membrane is prepared by the following method: (1) Preparation of modified liquid: The modified liquid includes the following raw materials in parts by weight: 5 to 20 parts of a modifier, 30 to 94.5 parts of a diluent, and 0.5 to 3 parts of an additive, wherein the modifier is one or more of a C6 waterproofing agent, a C8 waterproofing agent, a polyurethane fluorine-free waterproofing agent, and an acrylic fluorine-free waterproofing agent, the diluent is pure water, and the additive is one or more of formic acid, acetic acid, and hydrochloric acid; (2) Using a hydrophilic polyethersulfone membrane as a base membrane, immersing the base membrane in the modified solution, and then drying to obtain a hydrophobic polyethersulfone microporous membrane.

2. The use according to claim 1, characterized in that: The application also includes: the sterile respirator is a respirator in a bioreactor.

3. The use according to claim 1, characterized in that: The pore size of the base membrane in step (2) is 0.05 μm to 5 μm.

4. The use according to claim 1, characterized in that: The step (2) further includes: soaking the base film in the modifying liquid in one of the following two ways: placing the base film in the modifying liquid for soaking; or transferring the base film into the modifying liquid for soaking.

5. The use according to claim 4, characterized in that: The soaking time is 5 to 8 minutes.

6. The use according to claim 4, characterized in that: When the base film is conveyed into the modifying liquid for immersion, the conveying speed of the base film is 2 m / min to 2.5 m / min.

7. The use according to claim 4, characterized in that: The base film is immersed in the modification liquid at 20-30°C.

8. The use according to claim 1, characterized in that: The drying temperature in step (2) is 150-160°C.

9. The use according to claim 1, characterized in that: The water contact angle of the hydrophobic polyethersulfone microporous membrane is greater than 100°.

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