CN116531962A - Polyamide microfiltration membrane and preparation method thereof - Google Patents

Polyamide microfiltration membrane and preparation method thereof Download PDF

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Publication number
CN116531962A
CN116531962A CN202310819936.6A CN202310819936A CN116531962A CN 116531962 A CN116531962 A CN 116531962A CN 202310819936 A CN202310819936 A CN 202310819936A CN 116531962 A CN116531962 A CN 116531962A
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film
additive
polyamide
liquid
casting
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请求不公布姓名
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Maiborui Biofilm Technology Nantong Co ltd
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Maiborui Biofilm Technology Nantong Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0011—Casting solutions therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/147—Microfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B01D2323/2182—Organic additives
    • B01D2323/21823—Alcohols or hydroxydes, e.g. ethanol, glycerol or phenol
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B01D2323/2182—Organic additives
    • B01D2323/21825—Ketones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B01D2323/2182—Organic additives
    • B01D2323/21826—Acids, e.g. acetic acid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B01D2323/2182—Organic additives
    • B01D2323/21837—Amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/218—Additive materials
    • B01D2323/2182—Organic additives
    • B01D2323/21839—Polymeric additives
    • B01D2323/2185—Polyethylene glycol
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Abstract

The invention relates to a polyamide micro-filtration membrane and a preparation method thereof, wherein the preparation method comprises the following steps: s1, adding polyamide resin and a first additive into a first solvent, and stirring to obtain a casting solution; s2, casting the cast film to a release film, scraping the film by using a scraper to obtain a liquid film, standing, placing the liquid film in a coagulating bath for treatment, taking out and drying to obtain the polyamide micro-filtration film, wherein the coagulating bath comprises a second additive and water. According to the preparation method, the specific types of first additives (polymers with smaller molecular weight and better compatibility with the second additives in the coagulating bath) are added into the casting film liquid, the first additives participate in the liquid film when the liquid film enters the coagulating bath and the polyamide resin touches water in the coagulating bath to perform crystallization, and the small molecular polymers can inhibit the natural crystallization of the polyamide resin into a spherical shape in the liquid-liquid phase conversion process, so that the polyamide resin is expanded and crystallized, a bicontinuous pore structure (namely through holes) is finally formed, and the flux of the polyamide microfiltration film is further improved.

Description

Polyamide microfiltration membrane and preparation method thereof
Technical Field
The invention belongs to the technical field of structural materials, and particularly relates to a polyamide microfiltration membrane and a preparation method thereof.
Background
Polyamide (PA for short) is also called nylon, is a transparent thermoplastic plastic, has the advantages of high melting point, excellent strength and toughness, good oxygen flame retardance, wear resistance and the like, is widely applied to the fields of electric appliances, traffic, machinery, textile and the like, and is an ideal engineering plastic and fiber material. Because polyamide has good gas barrier property and low-temperature brittleness resistance, polyamide is also widely applied to the field of film materials.
Most of the polyamide microfiltration membrane products in the market are composite membranes with supporting layers, for example, patent document with publication number of CN112619449A discloses a nylon membrane, which comprises a nylon layer, wherein the nylon layer comprises a netlike nylon material entity part and a hollow part, the nylon material entity part forms a fibrous structure, the nylon material entity part forms a main body part and a plurality of synapses, the main body part forms a sheet-shaped and/or strip-shaped structure, the main body part is connected with the main body part, and/or the main body part is connected with the synapses, and the synapses on the surface of the nylon layer and/or the main body part extends or is connected in the thickness direction of the nylon layer. However, the composite membrane with the support layer has the problems that the support layer is easy to peel, the pore size distribution is uneven, and the dissolution of the membrane and the extraction of the solvent are difficult to completely meet the industry standard. There are also few unsupported nylon membrane products, as disclosed in the patent publication No. CN103127845A, for the preparation of an unsupported polyamide microporous membrane by applying a solution of an aliphatic polyamide in a solvent system consisting of a solvent for the polyamide and a non-solvent to a specific film, allowing the solution to undergo phase separation and curing of the polymer-rich phase by means of a gel bath while forming a membrane structure, the solution of the polyamide in the solvent system comprising a complexing agent selected in such a way that, in the state of the solution, the complexing agent is homogeneously dissolved in the solvent system, and in the case of phase separation, the complexing agent and the polyamide complex to form a network microporous structure, the pure water flux of the membrane obtained being 1.33X10 -3 m 3 /m 2 /sec. However, the flux of such nylon membranes is small.
Disclosure of Invention
In view of the above, the invention aims to provide a polyamide microfiltration membrane and a preparation method thereof, so as to solve the technical problems that a composite membrane with a support layer is easy to peel, the pore size distribution is uneven, the dissolution of the membrane and the extraction of a solvent are difficult to completely meet the industry standard, and the like, and the flux of an unsupported nylon membrane is smaller.
In a first aspect, the present invention provides a method for preparing a polyamide microfiltration membrane, comprising:
s1, adding polyamide resin and a first additive into a first solvent, and stirring to obtain a casting solution, wherein the first additive comprises at least one of L-cystine, L-aspartic acid, caprolactam, polyethylene glycol, polyalcohol, citric acid, adipic acid, glycolic acid and tannic acid;
s2, casting the casting film to a release film, scraping the film by using a scraper to obtain a liquid film, standing, placing the liquid film in a coagulating bath for treatment, taking out and drying to obtain the polyamide micro-filtration film, wherein the coagulating bath comprises a second additive and water, and the second additive comprises at least one of N-methylpyrrolidone, phenol, formic acid, methanol and ethanol.
In the present application, examples of the polyhydric alcohol include triethylene glycol, diethylene glycol, and the like.
Optionally, in step S1, the first solvent includes at least one of N-methylpyrrolidone, phenol, formic acid, methanol, and water.
Optionally, in step S1, the weight average molecular weight of the polyamide resin is 10000 to 30000, preferably 12000 to 28000.
Optionally, in step S1, the temperature of the stirring is 20-90 ℃, preferably 30-90 ℃.
Optionally, the concentration of the first additive in the casting solution in step S1 is 1wt% to 30wt%, preferably 5wt% to 30wt%.
Optionally, the concentration of the polyamide resin in the casting solution in step S1 is 10wt% to 40wt%, preferably 15wt% to 40wt%.
Optionally, in the film scraping process in step S2, the film scraping distance is 50-500 μm, preferably 100-500 μm.
Optionally, in step S2, the standing time is 1 to 200S, preferably 10 to 200S.
Optionally, in step S2, the temperature of the coagulation bath is 10-80 ℃, preferably 20-80 ℃.
Optionally, in step S2, the liquid film is placed in a coagulation bath for 1-30min, preferably 5-30min.
Optionally, the concentration of the second additive in the coagulation bath of step S2 is less than or equal to 80wt%.
Optionally, in step S2, the temperature of the drying is 60-90 ℃, preferably 70-90 ℃; the drying time is 5-15min, preferably 10-15min.
Optionally, in step S2, after the treatment in the coagulation bath and before the taking out and drying, the method further includes: the resulting film was treated in a cleaning bath.
Optionally, in step S2, the cleaning bath comprises a third additive comprising methanol or ethanol or a combination of both and water.
Optionally, in step S2, the temperature of the cleaning bath is 25-60 ℃, preferably 30-60 ℃.
Optionally, in step S2, the resulting film is subjected to a cleaning bath for 5-15min, preferably 10-15min.
Optionally, in the cleaning bath of step S2, the concentration of the third additive is less than or equal to 80wt%.
In a second aspect, the present invention provides a polyamide microfiltration membrane made according to the preparation method described above.
As described above, the polyamide microfiltration membrane and the preparation method thereof have the following beneficial effects:
(1) The polyamide microfiltration membrane has no supporting layer, and the problems that the supporting layer is easy to peel off and the like are solved.
(2) The method comprises the steps of adding a specific kind of first additive (polymer with smaller molecular weight and better compatibility with a second additive in a coagulating bath) into a casting film liquid, wherein the first additive participates in the liquid film when the liquid film contacts an aqueous solution for crystallization after entering the coagulating bath, and the small molecular polymer can inhibit the natural crystallization of the polyamide resin into a spherical shape in the liquid-liquid phase conversion process, so that the polyamide resin is expanded and crystallized, and finally a bicontinuous pore structure (namely a through hole) is formed; and the second additive with a certain proportion is added in the coagulating bath, so that the compact layer on the upper surface of the liquid membrane can be prevented from being generated in the phase change process, so that the permeation liquid can have more space to pass through from the upper surface, and the flux of the polyamide microfiltration membrane is further improved.
(3) According to the method, the specific type of the third additive is added into the cleaning bath, and the third additive can play a role in pore support in the drying process of the microfiltration membrane, so that the microfiltration membrane is not easy to shrink in the drying process, and the flux of the polyamide microfiltration membrane is further improved.
Drawings
FIG. 1 is an electron microscopic scan of the polyamide microfiltration membrane produced in example 1.
Detailed Description
The present invention will be further described with reference to the following specific examples, but it should be noted that the specific material ratios, process conditions, results, etc. described in the embodiments of the present invention are only for illustrating the present invention, and are not intended to limit the scope of the present invention, and all equivalent changes or modifications according to the spirit of the present invention should be included in the scope of the present invention. It should be noted that the term "wt%" as used herein refers to mass% unless otherwise specified.
The invention provides a preparation method of a polyamide micro-filtration membrane, which comprises the following steps:
s1, adding polyamide resin with weight average molecular weight of 10000-30000 and a first additive into a first solvent, and stirring at 20-90 ℃ to obtain a casting solution with the concentration of the first additive of 1-30 wt% and the concentration of the polyamide resin of 10-40 wt%;
wherein the first additive comprises at least one of L-cystine, L-aspartic acid, caprolactam, polyethylene glycol, polyalcohol, citric acid, adipic acid, glycolic acid and tannic acid;
the first solvent comprises at least one of N-methylpyrrolidone, phenol, formic acid, methanol and water;
s2, casting the casting film to a release film, and scraping the film by using a scraper to obtain a liquid film, wherein the film scraping distance is 50-500 mu m in the film scraping process; standing for 1-200s, then placing the liquid membrane in a coagulating bath at 10-80deg.C for 1-30min, placing the obtained membrane in a cleaning bath at 25-60deg.C for 5-15min, taking out, and oven drying at 60-90deg.C for 5-15min to obtain polyamide microfiltration membrane;
wherein the coagulating bath comprises a second additive and water, the second additive comprises at least one of N-methyl pyrrolidone, phenol, formic acid, methanol and ethanol, and the concentration of the second additive is less than or equal to 80wt%;
the cleaning bath comprises a third additive and water, wherein the third additive comprises methanol or ethanol or a combination of the methanol and the ethanol, and the concentration of the third additive is less than or equal to 80wt%.
The invention also provides a polyamide microfiltration membrane prepared according to the preparation method.
The present invention will be described in detail with reference to specific exemplary examples. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, as many insubstantial modifications and variations are within the scope of the invention as would be apparent to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below. It should be understood that in the following examples, only nylon 66 resin is exemplified as the specific case of polyamide resin, and those skilled in the art may select polyamide resins other than nylon 66 resin, such as nylon 6 resin, nylon II resin, nylon 12 resin, nylon 46 resin, nylon 610 resin, nylon 612 resin, nylon 1010 resin, etc.
Example 1
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 70g of nylon 66 resin with weight average molecular weight of 18000 and 70g of first additive polyethylene glycol into 160g of first solvent formic acid, stirring at 80 ℃ to obtain casting film liquid, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, uniformly scraping the film by using a scraper to obtain a liquid film, wherein the film scraping distance is 250 mu m in the film scraping process; standing for 1-200s, and then placing the liquid film in a coagulating bath at 25 ℃ for 5min to perform phase separation to form a film, wherein the coagulating bath consists of a second additive formic acid and pure water, and the concentration of the formic acid is 10wt%; treating the obtained film in a 25 ℃ cleaning bath for 15min, wherein the cleaning bath consists of a third additive methanol and pure water, and the concentration of the methanol is 80wt%; and then taking out and drying for 10min at 90 ℃ to obtain the polyamide micro-filtration membrane.
Example 2
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 100g of nylon 66 resin with weight average molecular weight of 10000 and 23g of first additive acrylic acid into 177g of first solvent N-methylpyrrolidone, stirring at 20 ℃ to obtain casting solution, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, and uniformly scraping the film by using a scraper to obtain a liquid film, wherein the scraping distance is 50 mu m; standing for 1s, and then placing the liquid film in a coagulating bath at 10 ℃ for 30min to perform phase separation and film formation, wherein the coagulating bath consists of a second additive N-methylpyrrolidone and pure water, and the concentration of the N-methylpyrrolidone is 80wt%; treating the obtained film in a cleaning bath at 40deg.C for 15min, wherein the cleaning bath comprises third additive ethanol and pure water, and the concentration of ethanol is 10wt%; and then taking out and drying for 10min at the temperature of 60 ℃ to obtain the polyamide micro-filtration membrane.
Example 3
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 60g of nylon 66 resin with weight average molecular weight of 30000 and 60g of first additive adipic acid into 180g of first solvent phenol, stirring at 90 ℃ to obtain casting solution, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, uniformly scraping the film by using a scraper to obtain a liquid film, wherein the film scraping distance is 500 mu m in the film scraping process; standing for 200s, and then placing the liquid film in a coagulating bath at 80 ℃ for 1min to perform phase separation and film forming, wherein the coagulating bath consists of a second additive phenol and pure water, and the concentration of the phenol is 5wt%; treating the obtained film in a 60 ℃ cleaning bath for 12min, wherein the cleaning bath consists of a third additive of methanol, ethanol and pure water, the concentration of the methanol is 5wt%, and the concentration of the ethanol is 5wt%; and then taking out and drying for 10min at the temperature of 75 ℃ to obtain the polyamide micro-filtration membrane.
Example 4
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 30g of nylon 66 resin with weight average molecular weight of 180000 and 3g of first additive tannic acid into 160g of first solvent methanol, stirring at 80 ℃ to obtain casting solution, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, uniformly scraping the film by using a scraper to obtain a liquid film, wherein the film scraping distance is 250 mu m in the film scraping process; standing for 1-200s, and then placing the liquid film in a coagulating bath at 25 ℃ for 5min to perform phase separation and film forming, wherein the coagulating bath consists of a second additive phenol and pure water, and the concentration of the phenol is 30wt%; treating the obtained film in a 35 ℃ cleaning bath for 8min, wherein the cleaning bath consists of a third additive ethanol and pure water, and the concentration of the ethanol is 15wt%; and then taking out and drying for 10min at 90 ℃ to obtain the polyamide micro-filtration membrane.
Example 5
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 60g of nylon 66 resin with weight average molecular weight of 180000 and 60g of first additive citric acid into 180g of first solvent methanol, stirring at 50 ℃ to obtain casting solution, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, uniformly scraping the film by using a scraper to obtain a liquid film, wherein the film scraping distance is 100 mu m in the film scraping process; standing for 120s, and then placing the liquid film in a coagulating bath at 60 ℃ for 15min to perform phase separation and film forming, wherein the coagulating bath consists of a second additive phenol and pure water, and the concentration of the phenol is 30wt%; treating the obtained film in a 35 ℃ cleaning bath for 8min, wherein the cleaning bath consists of a third additive ethanol and pure water, and the concentration of the ethanol is 15wt%; and then taking out and drying for 10min at 90 ℃ to obtain the polyamide micro-filtration membrane.
Example 6
The polyamide microfiltration membrane is prepared by the following steps:
s1, adding 35g of nylon 66 resin with weight average molecular weight of 180000 and 35g of first additive diethylene glycol into 180g of first solvent methanol, stirring at 60 ℃ to obtain casting solution, and standing and defoaming for 3 hours;
s2, casting the casting film after standing and defoaming to a release film, and uniformly scraping the film by using a scraper to obtain a liquid film, wherein the scraping distance is 300 mu m; standing for 150s, and then placing the liquid film in a coagulating bath at 45 ℃ for 20min to perform phase separation and film forming, wherein the coagulating bath consists of a second additive ethanol and pure water, and the concentration of the ethanol is 40wt%; the obtained membrane is placed in a cleaning bath at 40 ℃ for 10min, the cleaning bath consists of a third additive methanol and pure water, the concentration of the methanol is 30wt%, and then the polyamide micro-filtration membrane is obtained after taking out and drying at 70 ℃ for 10 min.
Comparative example 1
A polyamide microfiltration membrane was produced in the same manner as in example 1 except for the following conditions:
s1, adding 70g of nylon 66 resin with weight average molecular weight of 18000 into 160g of first solvent formic acid, stirring at 80 ℃ to obtain casting solution, and standing and defoaming for 3 hours.
Comparative example 2
A polyamide microfiltration membrane was produced in the same manner as in example 1 except for the following conditions:
s1, adding 70g of nylon 66 resin with weight average molecular weight of 18000 and 10g of first additive acrylic acid into 160g of first solvent N-methylpyrrolidone, stirring at 80 ℃ to obtain casting solution, and standing and defoaming for 3 hours.
Comparative example 3
A polyamide microfiltration membrane was produced in the same manner as in example 1 except for the following conditions:
s1, adding 70g of nylon 66 resin with weight average molecular weight of 18000 and 120g of first additive adipic acid into 160g of first solvent N-methylpyrrolidone, stirring at 80 ℃ to obtain casting solution, and standing and defoaming for 3 hours.
Comparative example 4
The present comparative example differs from the example in that: the first additive was tween 80.
Comparative example 5
The present comparative example differs from the example in that: the second additive is isopropanol.
Comparative example 6
The present comparative example differs from the example in that: the third additive was isopropanol and severely shrunken during film drying.
Structure testing
The polyamide microfiltration membrane obtained in example 1 was subjected to electron microscopy, and the results are shown in FIG. 1.
As can be seen from fig. 1, the polyamide microfiltration membrane prepared in example 1 has a plurality of through holes, that is, the polyamide microfiltration membrane prepared in this example has a bicontinuous porous structure and a uniform pore size distribution, and the result shows that the crystallization process of the polyamide crystals is inhibited by adjusting the proportion and the process.
Flux testing
The polyamide microfiltration membranes prepared in examples 1 to 6 and comparative examples 1 to 6 were subjected to measurement of pure water flux, first bubble point pressure and open cell content, and the results are shown in Table 1;
wherein, pure water flux and first bubble point pressure are detected according to the bubble point and average flow method of GB/T32361-2015 separation Membrane aperture test method;
the detection method of the aperture ratio comprises the following steps: and selecting SEM pictures of the upper surface of the film, and analyzing and calculating by using imageJ software to obtain the aperture ratio of the film.
TABLE 1 flux test results
Remarks: no indication is exceeded.
As can be seen from Table 1, the membranes prepared in examples 1-6 have good flux and bubble point properties and a high open cell ratio; whereas comparative examples 1-6 used too low or too high a content of the first additive or the films produced with the first additive, the second additive, and the three additives not falling within the scope of the present application had poor properties. The result shows that by adding specific types of first additives (polymers with smaller molecular weight and better compatibility with second additives in a coagulating bath) into the casting film liquid, the first additives participate in the liquid film when the liquid film enters the coagulating bath and contacts water in the coagulating bath to perform crystallization, and the small molecular polymers can inhibit the natural crystallization of the polyamide resin into a spherical shape in the liquid-liquid phase conversion process, so that the polyamide resin is expanded and crystallized, and finally a bicontinuous pore structure (namely through holes) is formed, thereby improving the flux of the polyamide microfiltration film. The third additive can play a role in pore support in the drying process of the microfiltration membrane, so that the microfiltration membrane is not easy to shrink in the drying process, and the flux of the prepared polyamide microfiltration membrane is further improved.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. A method for preparing a polyamide microfiltration membrane, comprising:
s1, adding polyamide resin and a first additive into a first solvent, and stirring to obtain a casting solution, wherein the first additive comprises at least one of L-cystine, L-aspartic acid, caprolactam, polyethylene glycol, polyalcohol, citric acid, adipic acid, glycolic acid and tannic acid;
s2, casting the casting film to a release film, scraping the film by using a scraper to obtain a liquid film, standing, placing the liquid film in a coagulating bath for treatment, taking out and drying to obtain the polyamide micro-filtration film, wherein the coagulating bath comprises a second additive and water, and the second additive comprises at least one of N-methylpyrrolidone, phenol, formic acid, methanol and ethanol.
2. The production method according to claim 1, wherein in step S1, the first solvent includes at least one of N-methylpyrrolidone, phenol, formic acid, methanol, and water;
and/or, in step S1, the weight average molecular weight of the polyamide resin is 10000-30000;
and/or, in the step S1, the temperature of stirring is 20-90 ℃.
3. The method according to claim 1, wherein the concentration of the first additive in the casting solution in step S1 is 1wt% to 30wt%;
and/or, in the film casting liquid in the step S1, the concentration of the polyamide resin is 10-40 wt%.
4. The method according to claim 1, wherein in the film scraping process in step S2, the film scraping distance is 50-500 μm;
and/or, in the step S2, the standing time is 1-200S.
5. The method according to claim 1, wherein in step S2, the temperature of the coagulation bath is 10-80 ℃;
and/or, in the step S2, the liquid film is placed in a coagulating bath for treatment for 1-30min;
and/or, in the coagulating bath of the step S2, the concentration of the second additive is less than or equal to 80wt%;
and/or in the step S2, the drying temperature is 60-90 ℃ and the drying time is 5-15min.
6. The method according to claim 1, wherein in step S2, after the treatment in the coagulation bath and before the removal and drying, the method further comprises: the resulting film was treated in a cleaning bath.
7. The method of claim 6, wherein in step S2, the cleaning bath comprises a third additive comprising methanol or ethanol or a combination of both and water.
8. The method of claim 6, wherein in step S2, the temperature of the cleaning bath is 25-60 ℃;
and/or, in the step S2, the obtained film is placed in a cleaning bath for 5-15min.
9. The method according to claim 6, wherein the concentration of the third additive in the cleaning bath in step S2 is 80 wt.% or less.
10. A polyamide microfiltration membrane made according to the method of any one of claims 1-9.
CN202310819936.6A 2023-07-06 2023-07-06 Polyamide microfiltration membrane and preparation method thereof Pending CN116531962A (en)

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CN110368822A (en) * 2019-08-09 2019-10-25 四川斯派恩新材料有限公司 A kind of high temperature resistant semi-aromatic seperation film and preparation method thereof
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