CN114950162A - High-liquid-permeability PTFE (polytetrafluoroethylene) membrane and preparation method thereof - Google Patents
High-liquid-permeability PTFE (polytetrafluoroethylene) membrane and preparation method thereof Download PDFInfo
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- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 88
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 88
- 239000012528 membrane Substances 0.000 title claims abstract description 69
- 238000002360 preparation method Methods 0.000 title claims abstract description 6
- -1 polytetrafluoroethylene Polymers 0.000 title abstract description 6
- 238000000034 method Methods 0.000 claims abstract description 19
- 230000005855 radiation Effects 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 238000002791 soaking Methods 0.000 claims abstract description 12
- 230000035699 permeability Effects 0.000 claims abstract description 10
- 238000009832 plasma treatment Methods 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 150000001875 compounds Chemical class 0.000 claims description 12
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000007598 dipping method Methods 0.000 claims description 9
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 8
- 229910052753 mercury Inorganic materials 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- PQUCIEFHOVEZAU-UHFFFAOYSA-N Diammonium sulfite Chemical compound [NH4+].[NH4+].[O-]S([O-])=O PQUCIEFHOVEZAU-UHFFFAOYSA-N 0.000 claims description 6
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 6
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 6
- 239000004327 boric acid Substances 0.000 claims description 6
- 230000005587 bubbling Effects 0.000 claims description 6
- 229910000365 copper sulfate Inorganic materials 0.000 claims description 6
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims description 6
- 238000005470 impregnation Methods 0.000 claims description 6
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 6
- 235000011152 sodium sulphate Nutrition 0.000 claims description 6
- 235000010265 sodium sulphite Nutrition 0.000 claims description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 4
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 4
- 150000002170 ethers Chemical class 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- 150000007524 organic acids Chemical class 0.000 claims description 4
- 238000012360 testing method Methods 0.000 claims description 4
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 239000001307 helium Substances 0.000 claims description 3
- 229910052734 helium Inorganic materials 0.000 claims description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 235000005985 organic acids Nutrition 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims description 2
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 claims description 2
- 150000001491 aromatic compounds Chemical class 0.000 claims description 2
- 239000005388 borosilicate glass Substances 0.000 claims description 2
- 239000008367 deionised water Substances 0.000 claims description 2
- 229910021641 deionized water Inorganic materials 0.000 claims description 2
- 238000009826 distribution Methods 0.000 claims description 2
- 229910001507 metal halide Inorganic materials 0.000 claims description 2
- 150000005309 metal halides Chemical class 0.000 claims description 2
- 150000002989 phenols Chemical class 0.000 claims description 2
- 229910001388 sodium aluminate Inorganic materials 0.000 claims description 2
- 238000001228 spectrum Methods 0.000 claims description 2
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 claims description 2
- 229920002545 silicone oil Polymers 0.000 claims 1
- 239000002253 acid Substances 0.000 abstract description 2
- 238000000151 deposition Methods 0.000 abstract description 2
- 230000002045 lasting effect Effects 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 150000003254 radicals Chemical class 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000007774 longterm Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000000231 atomic layer deposition Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical class FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000010200 validation analysis Methods 0.000 description 1
Classifications
-
- 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
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/36—Polytetrafluoroethene
-
- 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
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/027—Nanofiltration
-
- 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
-
- 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
- B01D2325/00—Details relating to properties of membranes
- B01D2325/36—Hydrophilic membranes
-
- 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 discloses a preparation method of a PTFE (polytetrafluoroethylene) membrane with high liquid permeability, which comprises the following steps: 1) selecting a PTFE base film; 2) placing the PTFE base film in a reaction cavity of a vacuum plasma treatment instrument, and pretreating the front side and the back side of the PTFE base film; 3) soaking the PTFE membrane subjected to the plasma treatment in a pre-soaking solution for not less than 3 min; 4) placing one side or two sides of the soaked PTFE membrane under an ultraviolet radiation lamp for irradiation treatment, then repeating the step 3), and placing the other side or two sides of the PTFE membrane under an ultraviolet radiation lamp for irradiation treatment; 5) step 3) and step 4) are carried out for more than 1 time, and the total ultraviolet irradiation time is 1-60 min. Compared with a method for depositing on the surface of the PTFE membrane, the method is more environment-friendly, the treated PTFE membrane has lasting hydrophilic performance, and the treated PTFE membrane still has performance parameters before soaking after being soaked in strong acid and dried.
Description
Technical Field
The invention relates to the technical field of separation membranes, in particular to a PTFE (polytetrafluoroethylene) membrane with high liquid permeability and a preparation method thereof.
Background
Polytetrafluoroethylene (PTFE) is a special engineering plastic with excellent comprehensive performance and has the reputation of the king plastic. In the polytetrafluoroethylene molecule, CF2 units are arranged in a zigzag shape, and fluorine atoms protect carbon atom chains which are easy to corrode, so that a protective layer with low surface energy is formed. Therefore, the PTFE film has the advantages of excellent chemical stability, corrosion resistance, sealing property, high lubrication non-adhesiveness, good ageing resistance, excellent temperature resistance and the like, and is widely applied to the filtration fields of agriculture, industry, medical health, food and the like. However, the material has highly symmetrical molecular structure, high crystallinity and no active group, so that the material has very low surface energy, extremely high surface hydrophobicity, poor wettability and low permeability in liquid filtration based on water, so that the energy consumption of filtration is high, and the application of a PTFE membrane is limited. Therefore, a modification treatment of the PTFE membrane is required.
The prior commonly used PTFE membrane hydrophilization modification methods are various, such as chemical modification treatment, for example, the Chinese patent application publication No. CN111111470A produces CaCO in situ on the membrane surface by inorganic salt solution 3 However, the process is complex, which brings environmental protection problem and has short service life; there is also a plasma treatment-atomic layer deposition method such as the method disclosed in chinese patent application publication No. CN 102773026a, but the modification effect is not maintained for a long time and the metal oxide deposited on the surface is easily peeled off.
Disclosure of Invention
The invention aims to solve the problems, and provides a simple and effective method for modifying the surface of a PTFE membrane, so as to prepare the PTFE membrane with high liquid permeability and solve the problem of low liquid permeability of the PTFE.
In order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of a PTFE membrane with high liquid permeability comprises the following steps:
1) selecting a PTFE base film: using PTFE microporous separation membrane as base membrane, the average pore diameter of the base membrane is about 50-400nm, and the BET surface area of the micropores of the membrane is about 0.01-1.2m 2 /g；
2) Placing a PTFE base film in a reaction cavity of a vacuum plasma treatment instrument, pretreating the front side and the back side of the PTFE base film, wherein the gas is nitrogen, helium or argon, the radio frequency power is kept at 75-350W, and the treatment time is 30-350 s;
3) dipping the PTFE membrane treated by the plasma in a pre-dipping solution for not less than 3min, wherein solute compounds of the pre-dipping solution are selected from one or more of sodium sulfate, sodium sulfite, ammonium sulfate, ammonium sulfite, sodium aluminate, copper sulfate, boric acid, hydrochloric acid, nitric acid, sulfuric acid, deionized water, alcohols, ethers, phenols, aromatic compounds, fluorocarbon compounds, organic acids, ethers, trichloroethylene, carbon tetrachloride, hydrogen peroxide and silicon oil;
the solute compound has high surface energy and hydrophilic performance, and can be combined with C bond to generate free radical.
4) Placing one side or two sides of the soaked PTFE film under an ultraviolet radiation lamp for irradiation treatment, then repeating the step 3), and placing the other side or two sides of the PTFE film under an ultraviolet radiation lamp for irradiation treatment; the ultraviolet wavelength is 190nm-400nm, and the ultraviolet radiation power density is 5mW/cm 2 -60000mW/cm 2 ；
5) Step 3) and step 4) are carried out for more than 1 time, and the total ultraviolet irradiation time is 1-60 min.
Preferably, the solute compound of the pre-impregnation solution is selected from one or more of sodium sulfate, sodium sulfite, ammonium sulfate, ammonium sulfite, copper sulfate, boric acid, hydrochloric acid, nitric acid, sulfuric acid, organic acids; the concentration of the pre-impregnation solution is 0.05 to 3mol/L, preferably 0.05 to 1 mol/L.
Further preferably, the solute compound of the pre-impregnation solution is selected from one or more of sodium sulfite, sulfuric acid, sodium sulfate, ammonium sulfite, copper sulfate and boric acid, and the concentration of each solute compound is 0.05-1mol/L, or 0.08-0.3mol/L, or 0.08-0.2mol/L, or 0.1-0.15mol/L, or 0.1-0.12 mol/L.
Preferably, the PTFE base membrane is placed in a reaction cavity of a vacuum plasma processor in the step 2), and the surface of the PTFE base membrane is pretreated for 60-180 s; and simultaneously treating the front and back surfaces of the PTFE base film, or treating one surface firstly and then treating the other surface in a turning way.
Preferably, the PTFE membrane after plasma treatment in the step 3) is soaked in the pre-liquid for 3-30min, or 4-25min, or 4-20min, or 6-18 min.
The ultraviolet light is a continuous spectrum, being random radiation. Random radiation means that all photons emitted by the light source have a random phase when propagating. Usually, the ordinary light source has random radiation, and the laser does not belong to random radiation.
The light source of the ultraviolet ray is a low-pressure medium-pressure mercury lamp of a quartz glass shell or a borosilicate glass shell, a high-pressure mercury lamp of the quartz glass shell, a pulse ultraviolet lamp, an ultraviolet metal halide lamp, a cold-cathode low-pressure mercury lamp or a hot-cathode low-pressure mercury lamp.
Preferably, the ultraviolet radiation power density is 10mW/cm 2 -20000mW/cm 2 Or 10mW/cm 2 -15000mW/cm 2 。
The high liquid permeability PTFE membrane of the present invention is prepared by any one of the above-mentioned methods.
The pore size distribution range of the PTFE membrane is 2-600nm, and the average pore size is about 50-400 nm;
the BET surface area of the micropores of the PTFE membrane is about 0.01 to 1.2m 2 /g；
The average tensile strength of the PTFE film is more than or equal to 8 MPa;
the contact angle of the PTFE film is 0-15 degrees at 25 ℃;
60% isopropanol solution test, the bubbling point is 7.5-55 psi;
under the water pressure of 14.5psi, the pure water permeation quantity of the PTFE membrane is more than or equal to 3ml/min 2 。
The invention utilizes the low-pressure vacuum plasma treatment technology, breaks the fluorocarbon bonds and the carbon-carbon bonds on the surface of the PTFE in an ion bombardment mode, generates a large amount of free radicals, and introduces active groups or hydrophilic groups at the positions of the free radicals by dipping in the pre-dipping solution in the second step, thereby increasing the free energy of the surface of the PTFE and improving the hydrophilic performance of the PTFE. However, after the two steps of treatment, the surface structure is unstable, and in the long-term use process, the hydrophilic group is broken, the fluorocarbon bond is reestablished, and the hydrophilic performance is gradually lost. After irradiation treatment, the method is favorable for reducing the content of surface fluorinion, thereby blocking the recovery of fluorocarbon bonds and achieving the purpose of long-term hydrophilic modification.
Because the PTFE membrane has excellent chemical inertness and is difficult to actually react with chemical substances, the PTFE membrane is activated by using low-pressure vacuum plasma, and can be better combined with a compound in a presoaking solution after activation, and when radiation irradiation is carried out, the compound can promote the modification of surface molecules by irradiation, so that the conversion from hydrophobicity to hydrophilicity is realized.
The invention has the beneficial effects that: compared with a method for depositing on the surface of a PTFE membrane, the technical scheme of the invention is more environment-friendly, the treated PTFE membrane has longer hydrophilic performance, still has performance parameters before soaking after soaking in strong acid such as 1.28g/cm sulfuric acid or 30% hydrochloric acid for 3h and drying, has no obvious attenuation on average tensile strength, bubbling point pressure and pure water permeation, has the extract content of the PTFE membrane in a soaking solution lower than 500ppm or even lower, and does not influence the use of the PTFE membrane in liquid.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to be limiting.
The experimental methods in the following examples are all conventional methods unless otherwise specified; the chemical reagents used, unless otherwise specified, are conventional in the art and are commercially available.
Main materials and instruments:
the PTFE membrane is a product of Chongqing Baoman New Material Co., Ltd, and the thickness is 50 um.
The vacuum plasma processor was a CD 1200PLC model from Europlasma.
The PTFE membrane with high liquid permeability is prepared according to the following steps:
1) selecting a PTFE base film: the microporous PTFE separating membrane is used as a base membrane, and the BET surface area of the micropores of the membrane is about 0.01-1.2m 2 /g。
2) The PTFE base film is placed in a reaction cavity of a vacuum plasma treatment instrument and is pretreated, nitrogen, helium or argon is selected as gas, the radio frequency power is kept at 75-350W, the treatment time is 30-350s, and the front side and the back side of the PTFE base film are treated once respectively.
3) And (3) soaking the PTFE membrane subjected to plasma treatment in a front soaking solution, wherein solute compounds of the front soaking solution have high surface energy and hydrophilic performance and can be combined with C bonds to generate free radicals.
4) Placing one side of the soaked PTFE membrane under an ultraviolet radiation lamp for irradiation treatment, then repeating the step 3), and placing the other side of the PTFE membrane under an ultraviolet radiation lamp for irradiation treatment; the ultraviolet wavelength is 190nm-400nm, and the ultraviolet radiation power density is 5mW/cm 2 -60000mW/cm 2 ；
5) Repeating the steps 3) and 4) for 1 time, wherein the total ultraviolet irradiation time is 1-60 min. The total irradiation time in this example was equally divided among the multiple irradiations.
The PTFE-based membranes were modified as described above to prepare PTFE-modified membranes of examples 1 to 9 and comparative examples 1 to 3. The vacuum plasma processor adopts nitrogen gas and the radio frequency power is 200W when processing. Specific experimental conditions are shown in table 1.
TABLE 1 Experimental conditions
The products obtained in the examples and comparative examples were tested:
the pore size of the membrane was measured using a PMI test apparatus.
The tensile strength of the film was determined by tensile test (5582) according to ASTM D638 using a strain rate of 10mm/min at 23 ℃.
The bubbling point pressure test is tested by referring to GB-T14041.1-2007 validation of structural integrity of part 1 of the hydraulic filter element and determination of an initial bubbling point.
The contact angle is tested by referring to GB/T30447 and 2013 'method for measuring contact angle of nanometer film'.
The pure water permeation quantity is tested by referring to GB T32373 & 2015 reverse osmosis membrane test method.
The results of the measurements are shown in table 2:
TABLE 2
It is understood from the comparison between example 5 and comparative example 1 that the hydrophilic treatment effect can be improved by adding the plasma pretreatment, and it is understood from the comparison between example 5 and comparative examples 1 and 2 that the hydrophilic treatment effect can be more favorably promoted by the pre-dipping solution treatment.
The hydrophilic performance of the treated PTFE membrane is relatively durable, the products prepared in the examples 1 and 5 are soaked in 30% hydrochloric acid for 3 hours and then dried, relevant performance parameters of the products are detected (the result is shown in Table 3), and the average tensile strength, the contact angle, the bubbling point pressure and the pure water permeation quantity of the PTFE membrane are not obviously attenuated compared with those before soaking; and the extract content of the PTFE membrane in the soaking solution is lower than 500ppm, which indicates that the hydrophilic property of the PTFE membrane is durable, and the PTFE membrane can also be used in the liquid.
TABLE 3
Claims (10)
1. A preparation method of a PTFE membrane with high liquid permeability is characterized by comprising the following steps:
1) selecting a PTFE base film: using PTFE microporous separation membrane as base membrane, the average pore diameter of the base membrane is about 50-400nm, and the BET surface area of the micropores of the membrane is about 0.01-1.2m 2 /g；
2) Placing a PTFE base film in a reaction cavity of a vacuum plasma treatment instrument, pretreating the front side and the back side of the PTFE base film, wherein the gas is nitrogen, helium or argon, the radio frequency power is kept at 75-350W, and the treatment time is 30-350 s;
3) dipping the PTFE membrane treated by the plasma in a pre-dipping solution for at least 3min, wherein the solute compound of the pre-dipping solution is one or more selected from sodium sulfate, sodium sulfite, ammonium sulfate, ammonium sulfite, sodium aluminate, copper sulfate, boric acid, hydrochloric acid, nitric acid, sulfuric acid, deionized water, alcohols, ethers, phenols, aromatic compounds, fluorocarbons, organic acids, ethers, trichloroethylene, carbon tetrachloride, hydrogen peroxide and silicone oil;
4) placing one side or two sides of the soaked PTFE membrane under an ultraviolet radiation lamp for irradiation treatment, then repeating the step 3), and placing the other side or two sides of the PTFE membrane under an ultraviolet radiation lamp for irradiation treatment; the ultraviolet wavelength is 190nm-400nm, and the ultraviolet radiation power density is 5mW/cm 2 -60000mW/cm 2 ；
5) Step 3) and step 4) are carried out for more than 1 time, and the total ultraviolet irradiation time is 1-60 min.
2. The method of claim 1, wherein: the solute compound of the pre-impregnation solution is selected from one or more of sodium sulfate, sodium sulfite, ammonium sulfate, ammonium sulfite, copper sulfate, boric acid, hydrochloric acid, nitric acid, sulfuric acid and organic acid; the concentration of the pre-impregnation solution is 0.05 to 3mol/L, preferably 0.05 to 1 mol/L.
3. The method of claim 2, wherein: the solute compound of the pre-impregnation solution is selected from one or more of sodium sulfite, sulfuric acid, sodium sulfate, ammonium sulfite, copper sulfate and boric acid, and the concentration of each solute compound is 0.05-1mol/L, or 0.08-0.3mol/L, or 0.08-0.2mol/L, or 0.1-0.15mol/L, or 0.1-0.12 mol/L.
4. The method of claim 1, wherein: step 2) placing the PTFE base membrane in a reaction chamber of a vacuum plasma treatment instrument, and pretreating the surface of the PTFE base membrane for 60-180 s; and simultaneously treating the front and back surfaces of the PTFE base film, or treating one surface firstly and then treating the other surface in a turning way.
5. The method of claim 1, wherein: and 3) soaking the PTFE membrane subjected to the plasma treatment in the pre-liquid for 3-30min, or 4-25min, or 4-20min, or 6-18 min.
6. The method of claim 1, wherein: the ultraviolet light is a continuous spectrum, being random radiation.
7. The method of claim 1, wherein: the light source of the ultraviolet ray is a low-pressure medium-pressure mercury lamp of a quartz glass shell or a borosilicate glass shell, a high-pressure mercury lamp of the quartz glass shell, a pulse ultraviolet lamp, an ultraviolet metal halide lamp, a cold-cathode low-pressure mercury lamp or a hot-cathode low-pressure mercury lamp.
8. The method of claim 1, wherein: the power density of ultraviolet radiation is 10mW/cm 2 -20000mW/cm 2 Or 10mW/cm 2 -15000mW/cm 2 。
9. A highly liquid permeable PTFE membrane characterized by: prepared by the method of any one of claims 1 to 6.
10. The high liquid permeability PTFE membrane of claim 9, wherein:
the pore size distribution range of the PTFE membrane is 2-600nm, and the average pore size is about 50-400 nm;
the BET surface area of the micropores of the PTFE membrane is about 0.01 to 1.2m 2 /g；
The average tensile strength of the PTFE film is more than or equal to 8 MPa;
the contact angle of the PTFE film is 0-15 degrees at 25 ℃;
60% isopropanol solution test, the bubbling point is 7.5-55 psi;
under the water pressure of 14.5psi, the pure water permeation quantity of the PTFE membrane is more than or equal to 3ml/min.cm 2 。
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