CN101015773A - Porous polyvinylidene blending porous membrane and process for producing same - Google Patents

Porous polyvinylidene blending porous membrane and process for producing same Download PDF

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CN101015773A
CN101015773A CN 200610155601 CN200610155601A CN101015773A CN 101015773 A CN101015773 A CN 101015773A CN 200610155601 CN200610155601 CN 200610155601 CN 200610155601 A CN200610155601 A CN 200610155601A CN 101015773 A CN101015773 A CN 101015773A
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membrane
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liquid
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pvdf
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CN100411722C (en
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朱宝库
肖玲
杜春慧
徐又一
陈良刚
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Zhejiang University ZJU
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Zhejiang University ZJU
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Abstract

The invention discloses a plate-tubular porous membrane based on polyvinylidene fluoride mixture, and relative production. The membrane substantially comprises polyvinylidene fluoride, dual-block amphipathic epoxyethane, and inorganic particles. And the preparation comprises that mixing polyvinylidene fluoride, dual-block amphipathic epoxyethane, inorganic particles, aperture adjusting agent and polarity solvent to obtain the membrane preparing liquid, using said membrane preparing liquid into plate or tubular liquid membrane, immerging the liquid membrane into solidifying bath mainly comprising water to be solidified into plate or tubular membrane. And the apertures of plate membrane and tubular membrane are 0.01-5.0 and 0.01-0.2 micrometers. The hydrophilic chain section of amphipathic epoxyethane is abundant at the face or aperture walls of the membrane, while said two membranes are both better in hydrophilic property and permeable property, with significant resistance on organic adsorption, to be used as ultra-filter membrane and micro-filter membrane in membrane water treatment.

Description

Porous polyvinylidene blending porous membrane and preparation method thereof
Technical field
The invention belongs to the membrane technology field, the particularly dull and stereotyped and tubular porous membrane material of polyvinylidene blending thing, and their preparation method.
Background technology
Membrane separation technique is a kind of new separation technology, has advantages such as energy consumption is low, separating property good, non-secondary pollution, and is significant in fields such as medicine, chemical industry, the energy, food, environmental protection, water resources, representing the developing direction of isolation technics.Membrane material is the starting point and the core of membrane separation technique, also is the direction and the emphasis of membrane separation technique research and development.Separation membrane material mostly is polymer, mainly contain the modified fibre class, polysulfones, polyolefin, polyamide, Merlon, acrylic copolymer, fluoropolymer etc., microporous barrier by these polymer manufacture one-tenth, micro-filtration, ultrafiltration, nanofiltration, reverse-osmosis treated membrane process at liquid, gas separates and the purification membrane process, and gas-liquid separation membrane process and other are derived and occupied leading position in the film separation process.Should have character such as heat-resisting, acid and alkali-resistance, anti-microbial attack, anti-solvent as the polymer of membrane material, and cost is moderate, the system film is convenient.
Kynoar (PVDF) is a kind of easy crystal polymer thing, because C-F bond distance is short, bond energy is high, therefore having performances such as good mechanical intensity, chemical stability, hear resistance, weatherability, uvioresistant and antimicrobial erosion, is several separation polymer with Practical significance few in number.But, the most outstanding characteristics of PVDF are that the surface can be low, has extremely strong hydrophobicity, although this character makes it hydrophobic, nonpolar film aspect (as membrane extraction and film still-process) has remarkable advantages, but it is big at consumption, use wide, far reaching water treatment film aspect, the hydrophobicity of PVDF but becomes restriction pvdf membrane key in application problem, its main cause is: the strong hydrophobicity of (1) PVDF makes itself and organic matter, microorganism, has strong absorption/stick effect between the materials such as colloid, it is contaminated that these absorption/stick cause pvdf membrane to be very easy in water treatment procedure, thereby cause the decline of membrane flux, need frequent clean in the use, cause cost of water treatment to improve, treatment effeciency reduces; (2) that film surface and fenestra wall are not easy by water institute is wetting for the hydrophobicity that PVDF is strong, water treatment procedure needs bigger driving force, and (test shows, average pore size is the PVDF micro-filtration membrane of 0.2 μ m, under 0.2MPa pressure reduction, almost do not have water to pass through), thus cause the energy consumption cost of embrane method water treatment to improve.Therefore, pvdf membrane is carried out hydrophilically modified, have important and practical meanings with the cost that improves its flux, resistance tocrocking and the water treatment of reduction embrane method.
The main preparation methods of existing hydrophilic PVDF film can reduce two classes: a class is at first prepared hydrophobic pvdf membrane, and then realizes the hydrophiling of film through process for modifying surface, and this method can be called two-step method; Another kind of is by material modification or blend hydrophilic component, realizes the modification of film in the film preparation process simultaneously, and in fact this method belongs to one-step method.
Two-step method prepares in the hydrophilic PVDF membrane process, the first step is to adopt solution phase inversion or thermally induced phase separation to prepare the hydrophobicity pvdf membrane (at present, solution phase inversion and thermally induced phase separation are the main method of preparation pvdf membrane, wherein the system membrane efficiency height of solution phase inversion is used more general).The essence of the second step performing hydrophilic modification on surface is to introduce hydrophilic material layer on pvdf membrane surface and film inner hole wall, as polar group/little molecule or hydrophily macromolecular chain etc.The simplest surface hydrophilic method is the face coat method, be that little molecule of polarity or hydrophilic polymer form hydrophilic coating on the pvdf membrane surface, such as, Chinese patent CN200410024928 has reported at hydrophilic polymers such as pvdf membrane surface dip-coating polyvinyl alcohol, shitosans and has carried out PVDF hydrophilic microporous membrane modification technology.Though the initial hydrophily of the pvdf membrane of surface hydrophilic coating is good, but owing to only be physisorption between hydrophilic layer and the pvdf membrane, make that this hydroaropic substance easily runs off in the film application process, hydrophilic stability, persistence are poor, and the performance degradation of film is fast.In order to improve the stability of surface hydrophilic layer, also there is employing that the surface hydrophilic coating is carried out crosslinked report, announced a kind of at film surface-coated polymethyl vinyl ether (PVME) such as European patent EP 1654053, make the crosslinked raising hydrophilic layer of coating stability prepare the method for hydrophilic PVDF ultrafiltration, micro-filtration membrane again, but cross-linked layer is still shorter stable period, but also exists coating can influence the problem of membrane micropore structure.
By covalent bond hydrophilic substance is introduced the pvdf membrane surface and can improve hydrophilic layer and membrane-bound stability with the film inner hole wall.Simpler method is to carry out surface treatment with methods such as highly basic, plasmas less polar groups such as hydroxyl, amino, carboxyl are received on the film, but the density of handling polar group on the caudacoria surface is low, hydrophilic effect is relatively poor, and prolong in time, little polar group is moved to film inside along with the rotation of surperficial PVDF strand, the hydrophily decline.Though thereby this procedure is simple, but do not have Practical significance aspect hydrophilic at pvdf membrane.The hydrophilic polymer chain is grafted to that the PVDF surface can effectively reduce the loss of surface hydrophilic material and to the film internal migration.To pvdf membrane, the surface grafting initiation means of having reported have plasma, ultraviolet light, high-energy ray particle etc., the monomer that is used for surface grafting polymerization has acrylic acid, vinylpyrrolidone, oxirane, poly-propionamide etc., such as, the using plasma technology causes in the European patent EP 0249513, at the pvdf membrane surface grafting acrylic acid, acrylamide etc. contain unsaturated ethylene or acrylic monomer, realize the modification of pvdf membrane permanent hydrophilic.But, procedure complexity, cost height, efficient that surface grafting hydrophilic polymer chain carries out performing hydrophilic modification on surface are lower, simultaneously also can cause bigger damage to the mechanical strength of film, thereby the large-scale application for preparing the hydrophilicity kynoar microporous membrane technology by surface grafting polymerization seldom.
One-step method prepares the hydrophilic PVDF film and mainly is meant and realizes the hydrophiling of film simultaneously by the forming process of film from material of preparing.The pvdf membrane of one-step method preparation, it mainly is blending and modifying, promptly adopt hydrophilic polymer to mix as material of preparing with PVDF as second component, be prepared into the hydrophilic PVDF film through suitable method again, the hydrophilic component of mentioning in the correlation theory research report has PMA, polyvinyl acetate, polymethyl methacrylate, poly-1,4 butadiene adipic acid, polyvinylpyrrolidone, cellulose, polyethylene glycol etc.Adopt methods such as blend cellulose acetate, polyvinylpyrrolidone, hydroxy alkyl cellulose among U.S. Pat 4810384, European patent EP 1464477 and the EP1682238, prepare hydrophilic PVDF ultrafiltration/micro-filtration membrane, wherein the hydrophilizing agent components contents is no more than 30%; European patent EP 1654053 has announced that a kind of employing blend polymethyl vinyl ether (PVME) prepares the method for hydrophilic PVDF ultrafiltration/micro-filtration membrane; U.S. Pat 5151193 proposes the method by the hydrophilic pvdf membrane of blend sulfonated polyether-ether-ketone (PEEKSO) preparation; U.S. Pat 5914039 and US6024872 propose that polyvinyl alcohol and alpha-aluminium oxide are compound to prepare the method for hydrophilic film with the PVDF blend; U.S. Pat 6884350 provides a kind of method for preparing durable hydrophilic property PVDF reverse osmosis membrane: promptly earlier with methyl vinyl ether/copolymer-maleic anhydride and PVDF blend film forming, form the polyamide cross-linked layer with crosslinking agent again; In the European patent EP 1339777, earlier on the PVDF molecule, introduce polyethylene glycol oxide methacrylate (POEM), the polymethylacrylic acid big molecules of hydrophily such as (PMAA), prepared PVDF microporous barrier with the PVDF blend then with excellent hydrophilic by ATRP.
Comparatively speaking, adopt the one-step method of blending technology to prepare hydrophilic PVDF membrane process simple (with respect to the surface graft modification method), but, because hydrophilic component that adopts in the one-step method and PVDF are in that difference is very big in nature, POEM except report in the European patent EP 1339777, outside the PMAA grafting PVDF, most hydrophilic components and PVDF are also incompatible, in film, can form and be separated, hydrophilic component wherein also can be by creep effect stripping from film (polyvinylpyrrolidone especially that crawls in the use of film, water-soluble polymers such as polyethylene glycol), the hydrophily of film decays gradually, and the structure of film also can change.The hydrophilic PVDF film of one-step method preparation, belong to polymer blending material in essence, according to similar compatibility in the blended polymer material and structural property stabilisation principle, it is identical with main polymer (being the PVDF in this patent) to have part-structure or character in the polymer (being the hydrophilic polymer in this patent) as modified component.In the hydrophilic PVDF film of report, European patent EP 1339777 has been utilized this principle preferably, but the efficient of the Transfer Radical Polymerization grafting POEM, the PMAA on the PVDF raw material that are adopted in this patent is low, process complexity, the manufacturing cost height of film.
Different with the hydrophilic PVDF perforated membrane of having reported, this patent proposes and has realized to contain blending type PVDF dull and stereotyped and tubular porous membrane and their preparation method that the fluorocarbon chain amphipathic polymer is a hydrophilic component on the basis of fully experiment.The main component of disclosed hydrophilic PVDF perforated membrane is PVDF, contain two block amphipathic oxirane (CF of fluorocarbon chain 3(CF 2) x-O-(CH 2CH 2O) y-H) and inorganic nano-particle.On the principle, fluorocarbon chain in the amphipathic oxirane and PVDF have analog structure and character, and good stable is arranged in film, are difficult for running off, and make film have permanent hydrophily; Nano particles such as aluminium oxide wherein, titanium dioxide or silica can improve the mechanical strength of pvdf membrane.Described hydrophilic porous film preparation is based on solution phase inversion principle, realize by one-step method: at first PVDF, contain fluorocarbon chain amphipathic oxirane, inorganic particulate and aperture adjustment agent and be mixed and made into preparation liquid, dull and stereotyped and hollow technological forming obtains corresponding hydrophilic PVDF flat sheet membrane and tubular membrane through the solution phase inversion then.Because containing fluorocarbon chain amphipathic oxirane is the amphipathic di-block copolymer with AB type structure, under the coagulating bath effect, hydrophilic polyethylene oxide segment wherein stretches outside film in film forming procedure, enrichment on film surface and fenestra wall.Simultaneously, strong interaction between the PVDF in fluorocarbon chain section and the matrix is amphipathic nature block polymer " anchoring " film surface, utilize this PEO segment in the surface enrichment effect, the amphipathic hydrophilic ethylene oxide is turned into farthest showing.
Summary of the invention
The purpose of this invention is to provide a kind of porous polyvinylidene blending porous membrane and preparation method.
A kind of porous polyvinylidene blending porous membrane, this film are that the aperture is 0.01~5.0 micron, and thickness is 40~200 microns, and porosity is 50~80% flat sheet membrane; The component of film and mass percent are:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 74~89%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, wherein the numerical value of x is 8,12,16 or 18, and the numerical value of y is 4~20, and molecular weight is 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, 10~25%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 1~5%;
A kind of preparation method of porous polyvinylidene blending porous membrane comprises the steps:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24-48 hour down at 50~90 ℃, and the degassing obtains preparation liquid, and the mass percent of preparation liquid component is:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 10~20%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, 1~7%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 0.1~2.5%;
The aperture adjustment agent: water, glycerine, diethylene glycol ether, molecular weight are 2 * 10 4~2 * 10 6Polyvinylpyrrolidone or molecular weight be 2 * 10 2~2 * 10 3PEO, 1~5%;
Solvent: N, dinethylformamide, N, N-dimethylacetylamide or N-methyl pyrrolidone, 70~85%;
(2) striking film forming: 50~90 ℃ of preparation liquids are spread to thickness on dull and stereotyped carrier be the nascent dull and stereotyped liquid films of 100~500 μ m, and be that 20~40 ℃, relative humidity are to stop below 30 seconds in 40~90% the air in temperature; Nascent dull and stereotyped liquid film on the dull and stereotyped carrier immersed in 30~80 ℃ the coagulating bath film-forming more than 30 seconds;
The component of described coagulating bath and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~80%; Water, 20~100%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 30~50 ℃ water of solidifying is dry after 24~72 hours.
Another kind of porous polyvinylidene blending porous membrane, this film is that the aperture is 0.01~0.2 micron, and pipe thickness is 200~400 microns, and porosity is 50~80%, and external diameter is 1000~3000 microns a tubular membrane, the mass percent of membrane component is:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 74~89%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, wherein the numerical value of x is 8,12,16 or 18, and the numerical value of y is 4~20, and molecular weight is 5 * 10 2~* 10 3Contain fluorocarbon chain two block PEOs, 10~25%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 1~5%;
The preparation method of another kind of porous polyvinylidene blending porous membrane comprises the steps:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24-48 hour down at 50~90 ℃, and the degassing obtains preparation liquid, and the mass percent of preparation liquid component is:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 10~20%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, 1~7%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 0.1~2.5%;
The aperture adjustment agent: water, glycerine, diethylene glycol ether, molecular weight are 2 * 10 4~2 * 10 6Polyvinylpyrrolidone or molecular weight be 2 * 10 2~2 * 10 3PEO, 1~5%;
Solvent: N, dinethylformamide, N, N-dimethylacetylamide or N-methyl pyrrolidone, 70~85%;
(2) hollow film forming: with 20~80 ℃ of core liquid, 50~90 ℃ of preparation liquids are extruded into the nascent liquid film of tubulose through the spinning head of hollow molding, the nascent liquid film of this tubulose immerses after through the air gap below 30 centimetres in 20~80 ℃ the coagulating bath and is solidified into tubular membrane more than 10 seconds;
The component of described core liquid and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~80%; Water, 20~100%;
The component of described coagulating bath and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~50%; Water, 50~100%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 30~50 ℃ water of solidifying is dry after 24~72 hours.Advantage of the present invention:
The present invention has made full use of the principle of component surface migration enrichment in the principle of similar compatibility in the material science and the inversion of phases film-forming process, not only realized the film surface hydrophilic, and realize inner wall surface hydrophilic of film mesopore, the flux of separation process operation is big, pressure is little, energy consumption is low.
Again, the present invention adopts the AB type to contain fluorocarbon chain section two block PEOs, PEO segment wherein is to be known as the few a kind of polymer that has chemical stabilities such as outstanding hydrophilic ability, anti-organic matter absorption, biocompatibility, acid and alkali-resistance concurrently of number at present.The blend film of preparation gained is compared with the film of the water wetted material that contains environment sensitive groups such as carboxyl, amino, sulfonic acid, be more suitable in the processing of complicated component aqueous systems, the resistance tocrocking of film is better, and the cleaning frequency of film is longer, can reduce the expense of cleaning in the film use.
Again, the present invention adopts fluorocarbon chain in the two block PEOs and the strong interaction of PVDF, not only improved the compatibility between hydrophilic substance and the film matrix PVDF, and reduced of the negative effect of two block PEOs to membrane structure, make hydrophily two block PEOs more stable in film, be difficult in use running off, relatively and hydrophilic substances such as polyethylene glycol, polyvinylpyrrolidone, greatly improved hydrophilic stability of film and persistence.Experiment shows that the hydrophilic PVDF microporous barrier of preparation through after the vibration cleaning in 30 days, still can be kept certain hydrophily in 60 ℃ of water.
Again, the present invention adopts the humidification of inorganic nano-particle can increase substantially the mechanical strength of film, solves the lower problem of general solution phase inversion membrane intensity, and film can be used under higher pressure or hydraulic blow.
Again, the present invention has realized the integrated of the moulding of film and hydrophilic modification, has simplified filming technology, and the preparation efficiency height of film, cost are low.
Again, the present invention both had been suitable for flat sheet membrane preparation, also was suitable for the tubular membrane preparation, towards application wide.
Again, the present invention can effectively control structures such as the aperture that obtains film, porosity, thickness, and then the effective cutoff performance of controlling diaphragm.
Again, the structure of the present invention's employing is CF 3(CF 2) x-O-(CH 2CH 2O) yThe AB type of-H contains fluorocarbon chain section two block PEOs, and it is convenient to obtain, and cost is lower than the POEM that reported or the PVDF of PMAA grafting.
Description of drawings
Fig. 1 is the forming process schematic diagram of tubular porous membrane;
Fig. 2 (a) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 1-A;
Fig. 2 (b) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 1-B;
Fig. 2 (c) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 1-C;
Fig. 2 (d) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 2-B;
Fig. 2 (e) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 3-B;
Fig. 2 (f) is a PVDF blend plate porous membrane electron scanning micrograph (upper surface) among the embodiment 4-B;
Fig. 3 (a) is a PVDF blend tubular porous membrane electron scanning micrograph (section) among the embodiment 7-A;
Fig. 3 (b) is a PVDF blend tubular porous membrane electron scanning micrograph (inner surface) among the embodiment 7-A;
Fig. 3 (c) is a PVDF blend tubular porous membrane electron scanning micrograph (outer surface) among the embodiment 7-A;
Fig. 3 (d) is a PVDF blend tubular porous membrane electron scanning micrograph (section) among the embodiment 7-B;
Fig. 3 (e) is a PVDF blend tubular porous membrane electron scanning micrograph (inner surface) among the embodiment 7-B;
Fig. 3 (f) is a PVDF blend tubular porous membrane electron scanning micrograph (outer surface) among the embodiment 7-B;
Fig. 4 be among the embodiment 1-B PVDF blend plate porous membrane water contact angle with the washing time change curve;
Fig. 5 be among the embodiment 7-B PVDF alkene blend tubular porous membrane water contact angle with the washing time change curve.
The specific embodiment
Of the present invention have outstanding hydrophilic PVDF blend flat board and a tubular porous membrane, main component is PVDF, contains fluorocarbon chain two block amphipathic oxirane and inorganic particulates that the target of its preparation method is to realize above-mentioned three kinds of constituent contents, the distribution of component in membrane body and effective control of membrane pore structure (mainly being aperture and porosity) in essence.The preparation method of described film realizes that by preparation liquid preparation, inversion of phases film forming and three key steps of cleaning-drying wherein film liquid preparation, inversion of phases film forming are committed steps.
The preparation of film liquid is meant PVDF, the amphipathic oxirane that contains fluorocarbon chain, inorganic particulate, aperture adjustment agent and solvent, fully stirs 24-48 hour down at 50~90 ℃, leaves standstill then or reduce pressure to outgas to make uniform preparation liquid.
Among the present invention, the PVDF blend dull and stereotyped with tubular porous membrane in specification and the preparation liquid of PVDF, the amphipathic oxirane that contains fluorocarbon chain, three kinds of compositions of inorganic particulate in identical, three kinds of components in proportions are by three kinds of components in proportions decisions in the preparation liquid, preparation liquid is being made in the perforated membrane process, these three kinds of materials all are retained in the film basically.The effect of aperture conditioning agent is the pore structure of regulating perforated membrane in the preparation liquid, and through film-forming and cleaning, aperture adjustment agent and solvent are all transferred in coagulating bath or the rinse water.In the invention, the molecular weight 5 * 10 of the PVDF that adopts 4~2 * 10 6, structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H contains the molecular weight of the poly-amphipathic oxirane of fluorocarbon chain two blocks 5 * 10 2~2 * 10 3Between, inorganic particulate is that particle diameter is aluminium oxide, titanium dioxide or the silica of 5~200 nanometers.
Among the present invention, the membrane aperture conditioning agent is that water, glycerine, diethylene glycol ether, molecular weight are 2 * 10 4~2 * 10 6Polyvinylpyrrolidone or molecular weight are 2 * 10 2~2 * 10 3PEO, solvent are N, dinethylformamide, N, N-dimethylacetylamide or N-methyl pyrrolidone.
Among the present invention, the quality percentage composition of each component is in the preparation liquid: PVDF, 10~20%; Amphipathic oxirane, 1~7%; Inorganic particulate, 0.1~2.5%; The membrane aperture conditioning agent, 1~5%; Solvent, 70~85%.
Among the present invention, two block amphipathic ethylene oxide structures are CF 3(CF 2) x-O-(CH 2CH 2O) y-H, wherein, the numerical value of x is 8,12,16 or 18, preferred value is 16 or 18; The numerical value of y is 4~20, preferred 10-15.
PVDF blend flat board and tubular porous membrane are to adopt the moulding of solution inversion of phases principle among the present invention, are about to the liquid film that preparation liquid is made tabular or tubulose, again liquid film are immersed coagulating bath.Because coagulating bath is the non-solvent of PVDF, based on the Polymer Solution basic principle, liquid film (being the macromolecule concentrated solution) is with after coagulating bath (as water etc.) contacts, solvent in the polymer solution just spreads in coagulating bath, and the non-solvent in the coagulating bath spreads in polymer solution, forms dynamic (dynamical) double diffusion process.Along with constantly carrying out of this process, system generation liquid-liquid, liquid-solid phase-splitting, and then form the inner solid film that contains hole.
The forming method of PVDF plate porous membrane is among the present invention, be the nascent dull and stereotyped liquid films of 100~5001 μ m at first 50~90 ℃ of preparation liquids are spread to thickness on dull and stereotyped carriers such as glass or stainless steel, in temperature is that 20~40 ℃, relative humidity are to stop below 30 seconds in 40~90% the air, the nascent dull and stereotyped liquid film on the dull and stereotyped carrier is immersed in 30~80 ℃ the coagulating bath to be solidified into flat sheet membrane more than 30 seconds.Knifing can be continuous (being suitable for industrial production in batches) with solidifying, and also can be (being suitable for the laboratory) intermittently.
In the forming process of PVDF plate porous membrane, mainly adopt pure water or water and solvent mixture to do coagulating bath among the present invention, the component of coagulating bath and mass percent are: water, 20~100%; Solvent, N, N-dimethylacetylamide, N, identical with solvent in the preparation liquid a kind of in dinethylformamide or the N-methyl pyrrolidone, 0~80%.
The forming method of PVDF tubular porous membrane is among the present invention, with 20~80 ℃ of core liquid, 50~90 ℃ of preparation liquids are extruded into the nascent liquid film of tubulose through the spinning head of hollow molding, the nascent liquid film of this tubulose immerses after through the air gap below 30 centimetres in 20~80 ℃ the coagulating bath (promptly outer coagulating bath) and is solidified into tubular membrane more than 10 seconds, and the effect of wherein said core liquid (also can become interior coagulating bath) is the hollow structure of generation tubular membrane and the curing of tubular type liquid film inner surface; The effect of coagulating bath is to make liquid film begin to solidify (Fig. 1) from tubular type liquid film outer surface.
Among the present invention in the forming method of PVDF tubular porous membrane, the main pure water or water and solvent mixture of adopting done core liquid, the component of core liquid and mass percent are: N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~80%; Water, 20~100%; The component of described coagulating bath and mass percent are: N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~50%; Water, 50~100%.
The cleaning process that the PVDF blend is dull and stereotyped and tubular porous membrane prepares among the present invention, purpose is that aperture adjustment agent, solvent etc. are cleaned out from film fully, this process realized through soaking and washing in 30~50 ℃ water in 24~72 hours, the baking temperature that cleans caudacoria need carry out below 60 ℃, also can room temperature dry naturally.
Dull and stereotyped and the tubular porous membrane preparation method of PVDF blend among the present invention comprehensively realizes the adjusting of the structure and the performance of film by preparation liquid prescription and temperature, coagulation bath composition and temperature, the liquid film means such as time of staying in air of coming into being.During the preparation film that the aperture is big, water flux is high, can adopt the lower preparation liquid of concentration, or in forming process, adopt higher preparation liquid or coagulation bath temperature, or adopt the higher coagulating bath of solvent.
The invention will be further described below in conjunction with embodiment
The embodiment of the following stated PVDF blend flat board and tubular porous membrane and preparation method thereof, the implementation step of all embodiment is all identical with aforementioned implementation step.It should be noted that described embodiment is not construed as limiting the invention, all distortion that those of ordinary skill in the art can directly derive or associate from content disclosed by the invention all should be thought protection scope of the present invention.
The sign of hydrophilic polyethene hollow fiber microporous membrane among the present invention:
PVDF perforated membrane pore structure: aperture, the porosity of surveying film with mercury injection method (DEMO9500 type mercury injection apparatus, Micromecritics Instrument Corp, the U.S.).
The pattern of film: observe film microscopic appearance and film thickness with SEM (JSM-5510LV, Japan).
The film hydrophily: the hydrophily of film characterizes with the Static Water contact angle, adopts sessile drop method to go up at OCA20 contact angle measurement (German Dataphysics Instruments GmbH) and measures.
Hydrophilic stability is measured: PVDF porous fenestra is immersed in concussion continuously in 60 ℃ the water, takes out behind different time, measure water after 50 ℃ of vacuum drying at the film surface contact angle, represent hydrophilic stability from contact angle with the variation of concussion time.
The water flux of film: measure the water flux of film at 0.1MPa pressure with pure water, flat sheet membrane sample effective area is 75cm 2, tubular membrane sample effective area is 200cm 2(in the film external diameter).
Among the embodiment there be used primary raw material: Kynoar (PVDF): Shanghai 3F (FR904), Solvay (1015); Two block amphipathic oxirane CF 3(CF 2) x-O-(CH 2CH 2O) y-H (PTFE-b-PEG): DuPont (Mn=725,1500); Nano aluminium oxide (Al 2O 3): Haitai Nano Material Co., Ltd., Nanjing; Nano titanium oxide (TiO 2): ocean, Hangzhou chemical industry; Nano silicon (SiO 2): Haitai Nano Material Co., Ltd., Nanjing; Glycerine: Hangzhou chemical reagent Co., Ltd; Diethylene glycol ether: Shanghai Ling Jin Fine Chemical Co., Ltd; Polyvinylpyrrolidone (PVP): Shanghai chemical reagents corporation of Chinese Medicine group (K30, K60, K90); PEO (PEG): Shanghai chemical reagents corporation of Chinese Medicine group (Mn=600,1000); N, dinethylformamide (DMF): Shanghai Jingwei Chemical Co., Ltd.; N, N-dimethylacetylamide (DMAc): Shanghai Jingwei Chemical Co., Ltd.; N-methyl pyrrolidone (NMP): Shanghai San'aisi Reagent Co., Ltd..
Embodiment 1:
The implementation step of preparation polyvinylidene blending plate porous membrane:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24 hours down at 70 ℃, and the degassing obtains preparation liquid, and the mass percent of preparation liquid component is:
Kynoar (PVDF): FR904,10%;
Bad oxidative ethane of amphipathic (PTFE-b-PEG): structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight be 725 contain fluorocarbon chain two block PEOs, 1%;
Inorganic particulate: particle diameter is the titanium dioxide (TiO of 50 nanometers 2), 1%;
The aperture adjustment agent: molecular weight is 600 PEO (PEG), 3%;
Solvent: N, N-dimethylacetylamide (DMAc), 85%;
(2) striking film forming: 70 ℃ of preparation liquids are spread to thickness on dull and stereotyped carrier be the nascent dull and stereotyped liquid films of 150 μ m, and be that 20 ℃, relative humidity are to stop 10 seconds in 60% the air in temperature; With 60 seconds film-formings in the coagulating bath of 40 ℃ of the nascent dull and stereotyped liquid film immersions on the dull and stereotyped carrier;
Three kinds of prescriptions are adopted in described coagulating bath, and component and mass percent are respectively:
Prescription A (Fig. 2-a): water, 100%;
Prescription B (Fig. 2-b): N, N-dimethylacetylamide, 20%; Water, 80%;
Prescription C (Fig. 2-c): N, N-dimethylacetylamide, 50%; Water, 50%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 40 ℃ water of solidifying is dry after 48 hours.The structure of an implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 1 fully.
Table one:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PEG (600) DMAc 70 ℃, 24 hours 20 ℃, 5 hours
10% 1% 1% 3% 85%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 70℃ 150 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 40℃ 60 seconds
Prescription B DMAc,20%;H 2O,80%
Prescription C DMAc,50%;H 2O,50%
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 40 0.02 78 120
B 40 0.70 65 1740
C 40 1.20 69 2410
Embodiment 2:
Implementation step such as embodiment 1, the structure of every implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 2.
Table two:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PEG (600) DMAc 70 ℃, 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 84%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 70℃ 150 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 40℃ 60 seconds
Prescription B DMAc,20%;H 2O,80%
Clean The water logging bubble cleans Dry
Dry 40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 40 0.03 79 450
B 40 1.30 71 2650
Embodiment 3:
Implementation step such as embodiment 1, the structure of every implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 3.
Table three:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (1500) TiO 2 PEG (600) DMAc 70 ℃, 24 hours 20 ℃, 5 hours
10% 2% 2% 4% 82%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 70℃ 150 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 40℃ 60 seconds
Prescription B DMAc,20%;H 2O,80%
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 40 0.06 78 590
B 40 2.80 73 3450
Embodiment 4:
Implementation step such as embodiment 1, the structure of every implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 4.
Table four:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PEG (600) H 2O DMAc 70 ℃, 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 2% 82%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 70℃ 150 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 40℃ 60 seconds
Prescription B DMAc,20%;H 2O,80%
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 40 0.90 78 3400
B 40 4.3 74 4370
Embodiment 5:
Implementation step such as embodiment 1, the structure of every implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 5.
Table five:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PVP (K30) H 2O DMAc 70 ℃, 24 hours 20 ℃, 5 hours
15% 5% 1% 3% 2% 74%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 70 ℃ 250 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 60℃ 60 seconds
Prescription B DMAc,20%;H 2O,80%
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 80 0.70 76 1210
B 80 3.8 71 3770
Embodiment 6:
Implementation step such as embodiment 1, the structure of every implementation condition and gained PVDF blend plate porous membrane and performance are as shown in Table 6.
Table six:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (1500) TiO 2 Glycerine H 2O DMAc 70 ℃, 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 2% 82%
The striking liquid film Air ambient The preparation liquid temperature Thickness of liquid film The air time of staying
20 ℃, relative humidity 60% 50℃ 300 microns 10 seconds
Film-forming Coagulating bath component and mass percent Temperature Time
Prescription A H 2O,100% 40℃ 60 seconds
Prescription B DMAc,70%; H 2O,30%
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Thickness (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 100 0.70 75 1550
B 100 4.1 72 4170
Embodiment 7:
The implementation step of preparation polyvinylidene blending tubular porous membrane:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24 hours down at 70 ℃, and the degassing obtains preparation liquid, and the mass percent of preparation liquid component is:
Kynoar (PVDF): FR904,10%;
Amphipathic oxirane (PTFE-b-PEG): structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight be 725 contain fluorocarbon chain two block PEOs, 2%;
Inorganic particulate: particle diameter is the titanium dioxide (TiO of 50 nanometers 2), 1%;
The aperture adjustment agent: molecular weight is 600 PEO (PEG), 3%;
Solvent: N, dinethylformamide (DMF), 84%;
(2) hollow film forming: with 40 ℃ of core liquid, 70 ℃ of preparation liquids are extruded into the nascent liquid film of tubulose through the spinning head of hollow molding, the nascent liquid film of this tubulose immerses after through the air gap of 10 centimeter length in 40 ℃ the coagulating bath and to be solidified into tubular membrane in 60 seconds;
Described core liquid adopts two kinds of prescriptions, and component and mass percent are respectively:
Prescription A (Fig. 3-a, b, c): water, 100%;
Prescription B (Fig. 3-d, e, f): N, dinethylformamide, 20%; Water, 80%;
The component of described coagulating bath and mass percent are:
N, dinethylformamide, 20%; Water, 80%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 40 ℃ water of solidifying is dry after 48 hours.The structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are as shown in Table 7
Table seven:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PEG (600) DMF 70 ℃ 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 84%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 40 70 10 centimetres
Prescription B DMF,20%;H 2O,80%
Film-forming Coagulating bath component and mass percent Temperature Time
DMF,20%;H 2O,80% 40℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.02 58 120
B 400 1200 0.11 67 250
Embodiment 8:
Implementation step such as embodiment 7, the structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are as shown in Table 8.
Table eight:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (1015) PTFE-b-PEG (725) TiO 2 PEG (600) DMF 70 ℃ 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 84%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 40 70 10 centimetres
Prescription B DMF,20%;H 2O,80%
Prescription C DMF,50%;H 2O,50%
Solidify Coagulating bath component and mass percent Temperature Time
Film forming DMF,20%;H 2O,80% 40℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.02 56 110
B 400 1200 0.09 65 220
C 400 1200 1.10 69 270
Embodiment 9:
Implementation step such as embodiment 7, the structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are as shown in Table 9.
Table nine:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 PEG (600) NMP 70 ℃ 24 hours 20 ℃, 5 hours
15% 5% 1% 3% 76%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 60 70 10 centimetres
Prescription B NMP,20%;H 2O,80%
Film-forming Coagulating bath component and mass percent Temperature Time
NMP,20%;H 2O,80% 40℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.03 56 130
B 400 1200 0.12 67 230
Embodiment 10:
Implementation step such as embodiment 7, the structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are as shown in Table 10.
Table ten:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) TiO 2 Diethylene glycol ether DMF 70 ℃ 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 84%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 40 70 10 centimetres
Prescription B DMF,50%;H 2O,50%
Film-forming Coagulating bath component and mass percent Temperature Time
DMF, 20%; To H 2O,80% 40℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.03 59 130
B 400 1200 0.12 68 250
Embodiment 11:
Implementation step such as embodiment 7, the structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are shown in table ten one.
Table ten two
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) Al 2O 3 PEG (600) DMF 70 ℃ 24 hours 20 ℃, 5 hours
10% 3% 0.5% 5% 81.5%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 40 70 10 centimetres
Prescription B DMF,20%;H 2O,80%
Film-forming Coagulating bath component and mass percent Temperature Time
DMF,20%;H 2O,80% 60℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.04 61 200
B 400 1200 0.13 67 270
Embodiment 12:
Implementation step such as embodiment 7, the structure of every implementation condition and gained PVDF blend tubular porous membrane and performance are shown in table ten two.
Table ten two:
Preparation liquid Component and mass percent Stirring condition Vacuum outgas
PVDF (FR904) PTFE-b-PEG (725) SiO 2 PEG (600) DMF 70 ℃ 24 hours 20 ℃, 5 hours
10% 2% 1% 3% 84%
The tubulose liquid film Core fluid component and mass percent The core liquid temp The casting solution temperature The airspace
Prescription A H 2O,100% 40 50 10 centimetres
Prescription B DMF,50%;H 2O,50%
Film-forming Coagulating bath component and mass percent Temperature Time
DMF,30%;H 2O,70% 40℃ 60 seconds
Cleaning-drying The water logging bubble cleans Dry
40 ℃, 48 hours 20 ℃, 24 hours
Membrane structure and performance Prescription Pipe thickness (micron) External diameter (micron) Aperture (micron) Porosity (%) 0.1MP water flux (Lm -2·h -1)
A 400 1200 0.04 60 140
B 400 1200 0.12 68 250

Claims (4)

1, a kind of porous polyvinylidene blending porous membrane is characterized in that, film is that the aperture is 0.01~5.0 micron, and thickness is 40~200 microns, and porosity is 50~80% flat sheet membrane, and the component of film and mass percent are:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 74~89%;
Bad oxidative ethane of amphipathic: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, wherein the numerical value of x is 8,12,16 or 18, the numerical value of y is 4~20,10~25%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 1~5%;
2. the preparation method of a porous polyvinylidene blending porous membrane as claimed in claim 1 is characterized in that comprising the steps:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24-48 hour down at 50~90 ℃, and the degassing obtains preparation liquid, and the component of preparation liquid and mass percent are:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 10~20%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, 1~7%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 0.1~2.5%;
The aperture adjustment agent: water, glycerine, diethylene glycol ether, molecular weight are 2 * 10 4~2 * 10 6Polyvinylpyrrolidone or molecular weight be 2 * 10 2~2 * 10 3PEO, 1~5%;
Solvent: N, dinethylformamide, N, N-dimethylacetylamide or N-methyl pyrrolidone, 70~85%;
(2) striking film forming: 50~90 ℃ of preparation liquids are spread to thickness on dull and stereotyped carrier be the nascent dull and stereotyped liquid films of 100~500 μ m, and be that 20~40 ℃, relative humidity are to stop below 30 seconds in 40~90% the air in temperature; Nascent dull and stereotyped liquid film on the dull and stereotyped carrier immersed in 30~80 ℃ the coagulating bath film-forming more than 30 seconds;
The component of described coagulating bath and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~80%; Water, 20~100%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 30~50 ℃ water of solidifying is dry after 24~72 hours.
3, a kind of porous polyvinylidene blending porous membrane is characterized in that, film is that the aperture is 0.01~0.2 micron, and pipe thickness is 200~400 microns, and porosity is 50~80%, and external diameter is 1000~3000 microns a tubular membrane, and the component of film and mass percent are:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 74~89%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, wherein the numerical value of x is 8,12,16 or 18, the numerical value of y is 4~20,10~25%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 1~5%;
4. the preparation method of a porous polyvinylidene blending porous membrane as claimed in claim 3 is characterized in that comprising the steps:
(1) preparation of preparation liquid: Kynoar, amphipathic oxirane, inorganic particulate, aperture adjustment agent, solvent were stirred 24-4g hour down at 50~90 ℃, and the degassing obtains preparation liquid, and the component of preparation liquid and mass percent are:
Kynoar: molecular weight 5 * 10 4~2 * 10 6, 10~20%;
Amphipathic oxirane: structure is CF 3(CF 2) x-O-(CH 2CH 2O) y-H, molecular weight are 5 * 10 2~2 * 10 3Contain fluorocarbon chain two block PEOs, 1~7%;
Inorganic particulate: particle diameter is aluminium oxide, titanium dioxide or the silicon dioxide powder of 5~200 nanometers, 0.1~2.5%;
The aperture adjustment agent: water, glycerine, diethylene glycol ether, molecular weight are 2 * 10 4~2 * 10 6Polyvinylpyrrolidone or molecular weight be 2 * 10 2~2 * 10 3PEO, 1~5%;
Solvent: N, dinethylformamide, N, N-dimethylacetylamide or N-methyl pyrrolidone, 70~85%;
(2) hollow film forming: with 20~80 ℃ of core liquid, 50~90 ℃ of preparation liquids are extruded into the nascent liquid film of tubulose through the spinning head of hollow molding, the nascent liquid film of this tubulose immerses after through the air gap below 30 centimetres in 20~80 ℃ the coagulating bath and is solidified into tubular membrane more than 10 seconds;
The component of described core liquid and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~80%; Water, 20~100%;
The component of described coagulating bath and mass percent are:
N, N-dimethylacetylamide, N, dinethylformamide or N-methyl pyrrolidone wherein any one with preparation liquid in identical solvent, 0~50%; Water, 50~100%;
(3) cleaning-drying: flat sheet membrane soaking and washing in 30~50 ℃ water of solidifying is dry after 24~72 hours.
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