Hydrophobic modifier, hydrophobic modification method of polyethersulfone microporous membrane and membrane prepared therefrom

Abstract

The present invention belongs to the technical field of membrane material modification, and provides a hydrophobic modifier, a hydrophobic modification method of a polyethersulfone microporous membrane, and a membrane prepared therefrom, wherein the hydrophobic modifier comprises the following components 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. The hydrophobic modifier of the present invention has simple ingredients and low prices; the hydrophobic modification method uses the hydrophobic modifier, and the modification process is simple, the operation is simple, and no additional equipment is required, the cost is low, continuous production can be achieved, and it is easy to expand and scale production.

Description

Technical Field

[0001] The present application relates to the technical field of membrane material modification, and in particular to a hydrophobic modifier, a method for hydrophobic modification of a polyethersulfone microporous membrane, and a membrane prepared therefrom. 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 polyvinylidene fluoride (PVDF) membrane, and its inherent strong gamma resistance is more stable than polytetrafluoroethylene (PTFE) membrane. It is also resistant to high temperature and high pressure, and is an efficient membrane for filtration and ventilation applications. When making PES membrane, hydrophilic polymers such as PVP and PEG are often added as pore-forming agents, resulting in insufficient hydrophobicity of the prepared PES membrane, which limits its application.

[0003] There are two main methods for hydrophobic modification of polyethersulfone membranes:

[0004] 1. For the modification of the matrix before membrane formation, the commonly used methods are blending and copolymerization, such as synthesizing hydrophobic fluorinated oligomers or hydrophobic nanomaterials, blending the synthetic material with PES and making a hydrophobic membrane through the NIPS method. However, this method is time-consuming and labor-intensive, and the compatibility between the synthetic material and PES needs to be considered, which will also have a great impact on the membrane structure and mechanical strength.

[0005] 2. After the membrane is formed, the membrane is modified, that is, surface modification. Different from the matrix modification, the surface modification starts from the manufactured filter membrane and uses plasma treatment, surface chemical reaction treatment and other methods to modify the filter membrane.

[0006] For example, the patent with publication number CN103495352A discloses a method for preparing a modified polyethersulfone-based hydrophobic membrane for a gas-liquid membrane contactor, wherein anhydrous ethanol, ammonia water and silicate are mixed and stirred in a certain proportion to obtain a sol-gel liquid, the polyethersulfone-based membrane is surface-modified, and the polyethersulfone membrane after sol-gel treatment is modified with a low surface energy fluorinated siloxane to obtain a modified polyethersulfone-based hydrophobic membrane. The process of this method is cumbersome, requiring the preparation of silica gel, gel sol treatment, and then fluorination treatment, and the material with low surface energy is relatively expensive, which increases the production cost.

[0007] For example, Xing Wei et al. 4 Plasma grafting was used to fluorinate PES flat membranes and hollow fiber membranes, turning hydrophilic membranes into hydrophobic membranes. The membrane distillation effect was evaluated using 4% NaCl solution. The modified membranes had high water flux and high desalination rate. However, the disadvantage of this method is the instability of plasma and the high cost, which is not conducive to industrial production. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, the present invention provides a hydrophobic modifier, a method for hydrophobic modification of polyethersulfone microporous membrane and a membrane prepared therefrom, so as to solve the problems of the existing hydrophobic modification methods of membrane materials being complex, costly and difficult to mass produce.

[0009] To achieve the above and related purposes, the present invention adopts the following technical solutions:

[0010] The first aspect of the present invention provides a hydrophobic modifier, comprising the following components in parts by weight:

[0011] 5 to 20 parts of modifier, 30 to 94.5 parts of diluent, and 0.5 to 3 parts of additives, 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.

[0012] The second aspect of the present invention provides a method for hydrophobic modification of a polyethersulfone microporous membrane, comprising:

[0013] The hydrophilic polyethersulfone membrane is used as the base membrane, and the base membrane is immersed in a modifying liquid and then dried to obtain a hydrophobic polyethersulfone microporous membrane, wherein the modifying liquid is the above-mentioned hydrophobic modifier.

[0014] In one embodiment of the present application, the additive in the hydrophobic modifier is one or more of formic acid, acetic acid, and hydrochloric acid.

[0015] In one embodiment of the present application, the method also includes: immersing the base membrane in the modifying liquid in one of the following two ways: placing the base membrane statically in the modifying liquid for immersion; or transferring the base membrane into the modifying liquid for immersion, wherein the membrane pore size of the base membrane is 0.05μm to 5μm.

[0016] In one embodiment of the present application, the soaking time is 5 to 8 minutes.

[0017] 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.

[0018] In one embodiment of the present application, the base film is immersed in the modifying liquid at 20-30°C.

[0019] In one embodiment of the present application, the drying temperature is 150-160°C.

[0020] In one embodiment of the present application, the diluent in the hydrophobic modifier is pure water.

[0021] The third aspect of the present invention provides a polyethersulfone microporous membrane prepared according to the above hydrophobic modification method.

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

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

[0024] The hydrophobic modifier of the invention uses a waterproofing agent as a main hydrophobic modification component, has simple components and is low in price.

[0025] The hydrophobic modification method of the present invention uses the above-mentioned hydrophobic modifier to perform surface chemical reaction treatment by soaking the polyethersulfone microporous membrane, without changing the bulk structure of the polyethersulfone microporous membrane, and only changes the hydrophilicity of the membrane surface. The water contact angle of the prepared polyethersulfone microporous membrane is greater than 100°, and the hydrophobicity and air permeability are excellent.

[0026] The hydrophobic modification method of the present invention has a simple process, is easy to operate, does not require the addition of additional equipment, is low in cost, can realize continuous production, and is easy to expand and scale production.

[0027] 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

[0028] 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:

[0029] Figure 1 A schematic diagram of the device used for continuous production of the hydrophobic modification method of this application;

[0030] Figure 2 The electron microscope scanning images of the control group of Example 1 before and after modification;

[0031] Figure 3 This is an electron microscope scanning image of the polyethersulfone membrane in Example 1 before and after modification.

[0032] Reference numerals

[0033] 1: Unwinding mechanism; 2: Winding mechanism; 3: Modified liquid pool; 4: Hot wheel; 5: Rewinding mechanism; 6: Base film. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] The present invention provides a hydrophobic modifier, comprising the following components 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 hydrophobic modifier is as follows:

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

[0040] The present invention also provides a method for hydrophobic modification of a polyethersulfone microporous membrane, comprising: using a hydrophilic polyethersulfone membrane as a base membrane, immersing the base membrane in a modification liquid, and then drying to obtain a hydrophobic polyethersulfone microporous membrane, wherein the modification liquid is the above-mentioned hydrophobic modifier.

[0041] Furthermore, the method of immersing the base membrane in the modifying liquid is selected from any one of the following two methods: placing the base membrane statically in the modifying liquid for immersion; or transferring the base membrane into the modifying liquid for immersion, wherein the membrane pore size of the base membrane is 0.05μm to 5μm.

[0042] Furthermore, the soaking time is 5 to 8 minutes.

[0043] Furthermore, the conveying speed of the base film is 2 m / min to 2.5 m / min.

[0044] Furthermore, the base film is immersed in the modifying liquid at 20 to 30°C.

[0045] Furthermore, the drying temperature is 150-160°C.

[0046] 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 2m / min to 2.5m / min, preferably 2m / 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.

[0047] The present invention also provides a polyethersulfone microporous membrane, which is prepared according to the hydrophobic modification method.

[0048] Furthermore, the water contact angle of the polyethersulfone microporous membrane is greater than 100°.

[0049] 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.

[0050] Example 1

[0051] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 30°C until they are clear:

[0052] 10 parts of C6 waterproofing agent, 87 parts of pure water, and 3 parts of acetic acid.

[0053] (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 a hydrophobic modifier 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.

[0054] (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.

[0055] Example 2

[0056] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 25°C until they are clear:

[0057] 5 parts of polyurethane non-fluorine waterproofing agent, 94 parts of pure water, and 1 part of acetic acid.

[0058] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as a base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in a hydrophobic modifier 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.

[0059] (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.

[0060] Example 3

[0061] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 25°C until they are clear:

[0062] 5 parts of C6 waterproofing agent, 92 parts of pure water, and 3 parts of acetic acid.

[0063] (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 a hydrophobic modifier 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.

[0064] Comparative Example 1

[0065] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 25°C until they are clear:

[0066] 12 parts of polyurethane non-fluorine waterproofing agent, 78 parts of pure water, and 10 parts of acetic acid.

[0067] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as a base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in a hydrophobic modifier 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.

[0068] Comparative Example 2

[0069] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 25°C until they are clear:

[0070] 20 parts of polyurethane non-fluorine waterproofing agent, 70 parts of pure water, and 10 parts of acetic acid.

[0071] (2) A hydrophilic polyethersulfone membrane with a pore size of 0.45 μm was used as a base membrane. The base membrane in a transport state was uniformly passed through and completely immersed in a hydrophobic modifier 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.

[0072] Comparative Example 3

[0073] (1) Preparation of hydrophobic modifier: Mix the following components in parts by weight and stir at 25°C until they are clear:

[0074] 3 parts of C6 waterproofing agent, 95 parts of pure water, and 2 parts of acetic acid.

[0075] (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 a hydrophobic modifier 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.

[0076] Performance Testing

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The experimental data and analysis are as follows:

[0081] Table 1 Physical properties of polyethersulfone microporous membranes before and after modification in various embodiments and comparative examples

[0082]

[0083]

[0084] 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.

[0085] 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.

[0086] 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.

[0087] Table 2 Relative element content of the hydrophobically modified polyethersulfone membrane in the control group of Example 1

[0088]

[0089] Table 3 Relative element content of self-produced polyethersulfone membrane after hydrophobic modification in Example 1

[0090]

[0091]

[0092] 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.

[0093] 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.

[0094] 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. A method for hydrophobic modification of a polyethersulfone microporous membrane, characterized in that: The method comprises: using a hydrophilic polyethersulfone membrane as a base membrane, immersing the base membrane in a modification liquid, and then drying to obtain a hydrophobic polyethersulfone microporous membrane; Wherein, the modified liquid is a hydrophobic modifier, and the hydrophobic modifier includes the following components in parts by mass: 5-20 parts of modifier, 30-94.5 parts of diluent, 0.5-3 parts of additive, wherein the modifier is one or more of C6 waterproofing agent, C8 waterproofing agent, polyurethane fluorine-free waterproofing agent, 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. The hydrophobic modification method according to claim 1, characterized in that: The method also includes: immersing the base membrane in the modifying liquid in any one of the following two ways: placing the base membrane in the modifying liquid for immersion; or transferring the base membrane into the modifying liquid for immersion, wherein the membrane pore size of the base membrane is 0.05μm~5μm.

3. The hydrophobic modification method according to claim 1, characterized in that: The soaking time is 5~8min.

4. The hydrophobic modification method according to claim 1, 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.

5. The hydrophobic modification method according to claim 2, characterized in that: The base film is immersed in the modification liquid at 20-30°C.

6. The hydrophobic modification method according to claim 1, characterized in that: The drying temperature is 150~160℃.

7. A polyethersulfone microporous membrane, characterized in that: Prepared according to the hydrophobic modification method according to any one of claims 1 to 6.

8. The polyethersulfone microporous membrane according to claim 7, characterized in that The water contact angle of the polyethersulfone microporous membrane is greater than 100°.

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