CN104415671A - Method for preparing polyvinylidene fluoride alloy film by adopting compound thermally induced phase separation process - Google Patents
Method for preparing polyvinylidene fluoride alloy film by adopting compound thermally induced phase separation process Download PDFInfo
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Abstract
The invention discloses a method for preparing a polyvinylidene fluoride alloy film by adopting a compound thermally induced phase separation process. The method comprises the following steps: uniformly mixing polyvinylidene fluoride, a hydrophilic polymer and caprolactam; heating to a dissolving temperature in the presence of nitrogen, and keeping the temperature for 1.5-3h; after completely dissolving polyvinylidene fluoride, hydrophilic polymer and caprolactam, mixing at a dissolving temperature for 0.5-1.5h, standing to obtain a casting solution, and storing the casting solution at the dissolving temperature; and preparing the casting solution into a film, rapidly placing the scraped film in water with a preset temperature, naturally separating the film from a film plate by using water as a cold extraction agent to obtain the polyvinylidene fluoride alloy film. The method is simple in process, free from pollution, and relatively low in cost; the prepared polyvinylidene fluoride alloy film has excellent chemical stability, high mechanical strength and pollution resistance, is easily cleaned, provides a high-performance alloy film product for an MBR process in the fields of sewage treatment and water resource recycling, and is widely applied to the fields such as industries, medical treatment and sewage treatment.
Description
Technical field
The invention belongs to technical field of high polymer material preparation, be specifically related to a kind of method being prepared polyvinylidene fluoride alloy membrane by composite thermotropic phase separation method.
Background technology
Kynoar (PVDF) has outstanding solvent resistance, resistance to acids and bases, UV resistant and weatherability, is a kind of membrane material of excellence.The polyvinylidene fluoride film prepared with this membrane material obtains good application at the dirty water decontamination handles and biochemical pharmacy industry.Due to the hydrophobicity of PVDF, simple pvdf membrane when applying easily by the Organic Pollution in water, and not easy cleaning.Polyvinylidene fluoride alloy membrane is that blend alloy film can well improve the hydrophilicity of pvdf membrane by hydrophilic macromolecular compounds and PVDF blended obtained polymer porous film.The preparation of polymer porous film has multiple method, wherein phase inversion is one of modal method, liquid-liquid or solid-liquid phase mainly by controlling polymer solution are separated inversion of phases and carry out masking, according to the difference of the mode of being separated, phase separation method, thermally induced phase separation etc. can be divided into again.
Phase separation method (NIPS) is dissolved in solvent by PVDF forming homogeneous phase solution, then polymer solution is immersed in the non-solvent coagulating bath of PVDF, solvent now in polymer solution spreads to non-solvent, non-solvent spreads in polymer solution, Cambium periodicity double diffusion process, along with constantly carrying out of diffusion, system is separated, and forms the PVDF perforated membrane of different shape and structure through inversion of phases.
Thermally induced phase separation (TIPS) is that the one proposed by Castro the eighties in 20th century is caused being separated by temperature change and prepares the method for perforated membrane (as microfiltration membranes, milipore filter).Use higher boiling, low-molecular-weight single or mixed diluent at high temperature forms homogeneous phase solution with high polymer, homogeneous phase solution generation solid-liquid or liquid-liquid phase separation during cooling, then extract and remove diluent, thus obtain perforated membrane.The single diluent that TIPS adopts mostly is water-insoluble cosolvent, water insoluble, so also they must be extracted with other extractant after film forming, complex process, and unfriendly to environment.Can form homogeneous phase solution during high temperature, but usually Solid-Liquid Separation occurs in temperature-fall period, the film of formation is generally spherical loose structure, and film strength is not high, and water flux is also subject to certain impact.
Composite thermotropic phase separation method (c-TIPS) is that when utilizing high temperature, high polymer forms homogeneous phase solution, during cooling there is the principle of Thermal inactive (TIPS) and phase separation (NIPS) film forming in homogeneous phase solution simultaneously, namely in film forming procedure, water is extractant and cooling agent (hereinafter referred to as extraction cryogen), the top layer solvent of preparation liquid can occur to exchange with extraction water as refrigerant and cause phase separation, phase separation mainly occurs in film surface, affects to some extent cortex construction; High temperature casting solution exchanges with extraction water as refrigerant generation thermic simultaneously, causes Thermal inactive, affects body apertures structure.The film obtained by this method is made up of body (supporting layer) and cortex (filter course), and the film-strength obtained is high, flux large, and outer surface can have cortex, also can not have cortex.This method can be improved merely by the performance of TIPS institute masking, simultaneously also can according to the stuctures and properties changing coagulant liquid temperature controlling diaphragm easily.
Summary of the invention
Technical problem to be solved by this invention is to provide the method that simple, pollution-free, the lower-cost composite thermotropic phase separation method of a kind of technique prepares polyvinylidene fluoride alloy membrane.
The present invention solves the problems of the technologies described above adopted technical scheme: a kind of composite thermotropic phase separation method prepares the method for polyvinylidene fluoride alloy membrane, it is characterized in that step is:
1) hydrophilic macromolecule of the Kynoar of molecular weight 300,000 ~ 1,100,000, molecular weight 50,000 ~ 500,000 and caprolactam are mixed, wherein, the weight percentage of Kynoar is 10 ~ 30%, the weight percentage of hydrophilic macromolecule is 1.5 ~ 5%, and the weight percentage of caprolactam is 65 ~ 85%;
2) mixed Kynoar, hydrophilic macromolecule and caprolactam are heated to solution temperature under nitrogen protection, and keep 1.5 ~ 3h at such a temperature;
3) after Kynoar, hydrophilic macromolecule and caprolactam dissolve completely, under solution temperature, stir 0.5 ~ 1.5h, standing and defoaming, obtains casting solution, is preserved by casting solution under solution temperature;
4) above-mentioned casting solution is made film forming, the film just scraped be put into rapidly the water of predetermined temperature or dissolved in the aqueous solution of inorganic salts, using water as extraction cryogen, to film and lamina membranacea natural separation, namely obtain polyvinylidene fluoride alloy membrane.
As preferably, described hydrophilic macromolecule is the one in polyethylene glycol oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP).
As preferably, described step 2) and step 3) in solution temperature 110 ~ 180 DEG C.
As improvement, the predetermined temperature of the water of described step 4) or the aqueous solution that dissolved inorganic salts is relevant with the skin thickness of obtained polyvinylidene fluoride alloy membrane, during preparation, by regulating and controlling predetermined water or having dissolved the aqueous temperature of inorganic salts, control the skin thickness of polyvinylidene fluoride alloy membrane.
As preferably, the predetermined temperature of described water or the aqueous solution that dissolved inorganic salts is-20 ~ 90 DEG C.Inorganic salts can be sodium chloride, potassium nitrate or sodium nitrate, and its concentration is conventional interpolation.
Preferably, the thickness of the polyvinylidene fluoride alloy membrane of described step 4) is 20 ~ 300 μm.
Finally, the thickness of described polyvinylidene fluoride alloy membrane is 120 ~ 160 μm, and skin thickness is 5 ~ 80 μm.
Composite thermotropic phase separation method of the present invention prepares the method for polyvinylidene fluoride alloy membrane owing to adopting water miscible caprolactam as solvent, therefore can use water as extraction cryogen, thus can reduce the production cost of film and also pollution-free to environment.When using water as extraction cryogen, the top layer solvent of preparation liquid can occur to exchange with water and cause phase separation, phase separation occurs in film surface and forms cortex, the reduction of simultaneous temperature also can make film base body generation Thermal inactive. due to faster than mass transfer velocity more than 100 times of heat transfer rate, so when NIPS process not also to be able to do in time to top layer with inner future development, the entirety of film base there occurs the liquid-liquid caused by TIPS process and has been separated, the formation of cortex slow down the generation of mass transfer, so by phase separation thus the cortex formed is very thin, what its body occurred is all then Thermal inactive process, what then formed below cortex is equally distributed inierpeneirating network structure entirely, because cortex is very thin, therefore hinder very little to filter medium, the flux of film is just very high, because cortex and supporting layer are formed simultaneously, structure IPN, there is not the problem being easy to peel off with supporting layer, mechanical strength is good, this method is particularly suitable for preparation cortex, the milipore filter that flux is high.Meanwhile, the stuctures and properties of film also can be regulated and controled easily by the temperature changing coagulant liquid.
Compared with prior art, the invention has the advantages that: (1) adopts composite thermotropic phase separation method to be prepared, there is the process of thermally induced phase separation (TIPS) and phase separation (NIPS) in the process of film forming simultaneously, upper surface forms very thin cortex, and body is the high cancellated alloy film of porosity.The polyvinylidene fluoride alloy membrane that this method obtains is cortex and supporting layer one, equally distributed IPN reticular membrane structure, and compared with spherical membrane structure, made alloy film, water flux is large, and mechanical strength is high, is convenient to the structures and characteristics of film.(2) the diluent caprolactam adopted is water-soluble solvent, and when using water as cooling agent, water is simultaneously also as extractant, and namely water is as extraction cryogen, can obtain this alloy film easily, make technique simple; Meanwhile, solvent is easy to recycling, and therefore masking cost is low, also pollution-free to environment.(3) the present invention with the addition of hydrophilic macromolecule in the feed, improves the hydrophily of film, makes polyvinylidene fluoride alloy membrane keep the performance of permanent hydrophilic.(4) film-forming method technique of the present invention is simple, pollution-free, cost is lower, the polyvinylidene fluoride alloy membrane of preparation can be the MBR(note in sewage disposal, water resource recycling field: MBR, i.e. Membrane Bio-Reactor, also known as membrane bioreactor) technique provides high performance alloy film product, is widely used in fields such as industry, medical treatment, sewage disposals.
Accompanying drawing explanation
Fig. 1 is the SEM figure of the appearance structure of polyvinylidene fluoride alloy membrane prepared by the embodiment of the present invention 5;
Fig. 2 is the SEM figure of the appearance structure of polyvinylidene fluoride alloy membrane prepared by the embodiment of the present invention 6.。
Detailed description of the invention
Below in conjunction with accompanying drawing embodiment, the present invention is described in further detail.
Embodiment 1
The Kynoar 13.5g of precise caprolactam 84.5g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 1.5g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 120 DEG C; heating makes raw material dissolve completely; and keep 45 minutes at 120 DEG C; then electric mixer agitating solution is used 30 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 120 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 35 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 145 μm, skin thickness 50 μm.
The polyvinylidene fluoride alloy membrane that the present embodiment 1 is obtained, when probe temperature is 25 DEG C (following examples are tested all at this temperature), pure water flux is 3004.72L/ (m
2h).
Embodiment 2
The Kynoar 12g of precise caprolactam 84.7g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 3g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 130 DEG C; heating makes raw material dissolve completely; and 1.5h is kept at 130 DEG C; then electric mixer agitating solution is used 30 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 130 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 30 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 50 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 2 is obtained is 2082.54L/(m
2h).
Embodiment 3
The Kynoar 18.2g of precise caprolactam 80.5g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 130 DEG C; heating makes raw material dissolve completely; and 2h is kept at 130 DEG C; then electric mixer agitating solution is used 45 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 130 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 130 μm, skin thickness 20 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 3 is obtained is 441.4L/(m
2h).
Embodiment 4
The Kynoar 16.1g of precise caprolactam 80.7g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 4g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 140 DEG C; heating makes raw material dissolve completely; and 1h is kept at 140 DEG C; then electric mixer agitating solution is used 30 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 140 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 20 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 4 is obtained is 378.53L/(m
2h).
Embodiment 5
The Kynoar 22.5g of precise caprolactam 75.4g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2.5g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 140 DEG C; heating makes raw material dissolve completely; and 2h is kept at 140 DEG C; then electric mixer agitating solution 1h is used; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 140 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 20 μm.
The SEM figure of the appearance structure of polyvinylidene fluoride alloy membrane prepared by the embodiment of the present invention 5 is shown in Fig. 1, and as seen from Figure 1, obtained polyvinylidene fluoride alloy membrane is upper strata is dense layer surface, and thickness is 20 μm.Lower floor is the supporting layer of IPN mesh skeleton structure.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 5 is obtained is 214.22L/(m
2h).
The present embodiment 5 make polyvinylidene fluoride alloy membrane with under identical proportioning, the same terms, obtained film is compared, pure water flux raising 30%.
Embodiment 6
The Kynoar 23.1g of precise caprolactam 75.2g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2.4g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 140 DEG C; heating makes raw material dissolve completely; and 2.5h is kept at 140 DEG C; then electric mixer agitating solution 1h is used; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 140 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 38 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 120 μm, skin thickness 40 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 6 is obtained is 603.8L/(m
2h).
The SEM figure of the appearance structure of polyvinylidene fluoride alloy membrane prepared by the embodiment of the present invention 6 is shown in Fig. 2, as seen from Figure 2, obtained polyvinylidene fluoride alloy membrane is similar to the structure of Fig. 1, the degree causing phase separation process to be carried out due to its coagulant liquid temperature difference is large, and skin thickness is 40 μm.
Embodiment 7
The Kynoar 18.2g of precise caprolactam 80.3g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2g of 100,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 140 DEG C; heating makes raw material dissolve completely; and 2.5h is kept at 140 DEG C; then electric mixer agitating solution is used 40 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 140 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 25 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 30 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 7 is obtained is 691.3L/(m
2h).
Embodiment 8
The Kynoar 18.4g of precise caprolactam 80.1g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2g of 300,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 2.5h is kept at 150 DEG C; then electric mixer agitating solution is used 40 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 40 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 50 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 8 is obtained is 808.3L/(m
2h).
Embodiment 9
The Kynoar 18.5g of precise caprolactam 79.5g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2g of 500,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 2.5h is kept at 150 DEG C; then electric mixer agitating solution 1h is used; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 150 μm, skin thickness 35 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 9 is obtained is 574.6L/(m
2h).
Embodiment 10
The Kynoar 18g of precise caprolactam 80g, molecular weight 320,000, polyvinyl alcohol 2g; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition, adopt oil bath heating, used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 3h is kept at 150 DEG C, then use electric mixer agitating solution 1h, afterwards standing and defoaming in oil bath; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 20 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 120 μm, skin thickness 25 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 10 is obtained is 802.2L/(m
2h).
Embodiment 11
The Kynoar 22.5g of precise caprolactam 75g, molecular weight 320,000, polyvinylpyrrolidone 2.5g; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition, adopt oil bath heating, used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 1.5h is kept at 150 DEG C, then use electric mixer agitating solution 30 minutes, afterwards standing and defoaming in oil bath; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 20 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 120 μm, skin thickness 15 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 11 is obtained is 357.3L/(m
2h).
Embodiment 12
The Kynoar 12g of precise caprolactam 83.4g, molecular weight 550,000, molecular weight are the polyethylene glycol oxide 3g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 1.5h is kept at 150 DEG C; then electric mixer agitating solution is used 50 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 30 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 150 μm, skin thickness 40 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 12 is obtained is 482.5L/(m
2h).
Embodiment 13
The Kynoar 18.3g of precise caprolactam 81.5g, molecular weight 720,000, molecular weight are the polyethylene glycol oxide 2g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 160 DEG C; heating makes raw material dissolve completely; and 2h is kept at 160 DEG C; then electric mixer agitating solution 1h is used; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 160 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 20 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 13 is obtained is 241.4L/(m
2h).
Embodiment 14
The Kynoar 16.5g of precise caprolactam 85.7g, molecular weight 1,100,000, molecular weight are the polyethylene glycol oxide 4g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 160 DEG C; heating makes raw material dissolve completely; and 3h is kept at 160 DEG C; then electric mixer agitating solution 1h is used; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 160 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the water of 15 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 150 μm, skin thickness 25 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 14 is obtained is 278.53L/(m
2h).
Embodiment 15
The Kynoar 17.5g of precise caprolactam 79.5g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 2.5g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 140 DEG C; heating makes raw material dissolve completely; and 2h is kept at 140 DEG C; then electric mixer agitating solution is used 30 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 140 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the sodium-chloride water solution of 0 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 130 μm, skin thickness 10 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 15 is obtained is 178.6L/(m
2h).
Embodiment 16
The Kynoar 17.2g of precise caprolactam 80.5g, molecular weight 320,000, molecular weight are the polyethylene glycol oxide 3.5g of 50,000; pour in 250mL beaker after above three kinds of raw materials are stirred; under slowly leading to nitrogen protection condition; employing oil bath is heated; used oil bath temperature is 150 DEG C; heating makes raw material dissolve completely; and 1.5h is kept at 150 DEG C; then electric mixer agitating solution is used 45 minutes; standing and defoaming in oil bath afterwards; obtain casting solution, then casting solution is incubated preservation at 150 DEG C.Obtained casting solution is poured into striking film forming in template, the film just scraped being put into rapidly predetermined temperature is in the aqueous solution of the sodium nitrate of-18 DEG C, to film and lamina membranacea natural separation; Namely obtain polyvinylidene fluoride alloy membrane, the thickness of this polyvinylidene fluoride alloy membrane is 140 μm, skin thickness 13 μm.
The pure water flux of the polyvinylidene fluoride alloy membrane that the present embodiment 16 is obtained is 180.7L/(m
2h).
Claims (7)
1. composite thermotropic phase separation method prepares a method for polyvinylidene fluoride alloy membrane, it is characterized in that step is:
1) hydrophilic macromolecule of the Kynoar of molecular weight 300,000 ~ 1,100,000, molecular weight 50,000 ~ 500,000 and caprolactam are mixed, wherein, the weight percentage of Kynoar is 10 ~ 30%, the weight percentage of hydrophilic macromolecule is 1.5 ~ 5%, and the weight percentage of caprolactam is 65 ~ 85%;
2) mixed Kynoar, hydrophilic macromolecule and caprolactam are heated to solution temperature under nitrogen protection, and keep 1.5 ~ 3h at such a temperature;
3) after Kynoar, hydrophilic macromolecule and caprolactam dissolve completely, under solution temperature, stir 0.5 ~ 1.5h, standing and defoaming, obtains casting solution, is preserved by casting solution under solution temperature;
4) above-mentioned casting solution is made film forming, the film just scraped be put into rapidly the water of predetermined temperature or dissolved in the aqueous solution of inorganic salts, using water as extraction cryogen, to film and lamina membranacea natural separation, namely obtain polyvinylidene fluoride alloy membrane.
2. method according to claim 1, is characterized in that: described hydrophilic macromolecule is the one in polyethylene glycol oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP).
3. method according to claim 1, is characterized in that: described step 2) and step 3) in solution temperature 110 ~ 180 DEG C.
4. method according to claim 1, it is characterized in that: the predetermined temperature of the water of described step 4) or the aqueous solution that dissolved inorganic salts is relevant with the skin thickness of obtained polyvinylidene fluoride alloy membrane, during preparation, by regulating and controlling predetermined water or having dissolved the aqueous temperature of inorganic salts, control the skin thickness of polyvinylidene fluoride alloy membrane.
5. method according to claim 4, is characterized in that: the predetermined temperature of described water or the aqueous solution that dissolved inorganic salts is-20 ~ 90 DEG C.
6. method according to claim 1, is characterized in that: the thickness of the polyvinylidene fluoride alloy membrane of described step 4) is 20 ~ 300 μm.
7. method according to claim 6, is characterized in that: the thickness of described polyvinylidene fluoride alloy membrane is 120 ~ 160 μm, and skin thickness is 5 ~ 80 μm.
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| CN106823857A (en) * | 2015-12-07 | 2017-06-13 | 宁波大学 | A kind of Membrane Materials preparation method of PVDF-HFP hydrophobic membranes |
| CN110721598A (en) * | 2019-09-27 | 2020-01-24 | 贵州省材料产业技术研究院 | Preparation method of high-flux porous membrane |
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| CN106823857A (en) * | 2015-12-07 | 2017-06-13 | 宁波大学 | A kind of Membrane Materials preparation method of PVDF-HFP hydrophobic membranes |
| CN106823857B (en) * | 2015-12-07 | 2021-05-25 | 宁波大学 | Preparation method of PVDF-HFP hydrophobic membrane for membrane distillation |
| CN110721598A (en) * | 2019-09-27 | 2020-01-24 | 贵州省材料产业技术研究院 | Preparation method of high-flux porous membrane |
| CN110721598B (en) * | 2019-09-27 | 2022-03-29 | 贵州省材料产业技术研究院 | Preparation method of high-flux porous membrane |
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| CN104415671B (en) | 2017-07-14 |
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