CN100553752C - A kind of preparation method of vinylidene difluoride planar ultrafiltration membrane with gradient structure - Google Patents
A kind of preparation method of vinylidene difluoride planar ultrafiltration membrane with gradient structure Download PDFInfo
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- CN100553752C CN100553752C CNB2007100678607A CN200710067860A CN100553752C CN 100553752 C CN100553752 C CN 100553752C CN B2007100678607 A CNB2007100678607 A CN B2007100678607A CN 200710067860 A CN200710067860 A CN 200710067860A CN 100553752 C CN100553752 C CN 100553752C
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Abstract
The invention discloses the preparation method of a kind of gradient-structure polyvinylidene fluoride flat ultrafiltration.At first Kynoar and additive at high temperature are dissolved in the phosphoric acid ester solvent, to filter preparation liquid blade coating after the final vacuum deaeration then on nonwoven, in air, place certain hour, to scrape the nonwoven that scribbles preparation liquid at last immerses in the definite composition coagulating bath, successively, form the gradient-structure milipore filter through low temperature and two processes of high temperature gel.Such milipore filter can directly apply to the ultra-filtration and separation field, also can be used as support membrane and prepares various composite membranes.By the polyvinylidene fluoride (PVDF) ultrafiltration membrane of this method preparation, be the partially crystallizable layer near the film surface, lower floor is the amorphous layer of network-like pore structure, and the shrinkage factor of film is low, and mechanical property is superior.The inventive method is simple, and raw material is cheap and easy to get.
Description
Technical field
The present invention relates to polymeric membrane preparation and film separation field, relate in particular to the preparation method of a kind of gradient-structure polyvinylidene fluoride flat ultrafiltration.
Background technology
PVDF is a kind of crystalline polymer, and density is 1.78g/cm
3, vitrification point is-39 ℃, and crystalline melt point is 180 ℃, and decomposition temperature still can keep good intensity more than 316 ℃ under uniform temperature and pressurized.Excellent anticorrosive ageing-resistant performance is arranged, its film in outdoor placement one, do not become fragile in 20 years yet, have excellent acid and alkali resistance, oxidant, UV resistant and ageing resistace, chemical stability is good, organic solvents such as aliphatic hydrocarbon, alcohol, aldehyde do not have influence to it yet.Therefore, Kynoar (PVDF) micro-filtration membrane and milipore filter are widely used in fields such as medical treatment, environmental protection, water treatment, petrochemical industry, food industry, can also be applied to aspects such as film distillation, gas purification, organic solvent be refining.
Wrasidlo is at United States Patent (USP) 4,629, proposes the notion of asymmetric membrane in 563 and 4,774,039 for the first time, thinks that film cross-sectional aperture from the epidermis to the supporting layer gradually changes.Benzinger is at United States Patent (USP) U.S.4, uses TEP to make solvent in 384,047, and many hydroxy compounds are that non-solvent prepares the PVDF milipore filter.This film has fine and close top layer and network-like supporting layer, but water flux is less.Josefiak is at United States Patent (USP) U.S.4, the pvdf membrane that the method preparation of using hot dipping to go in 666,607 is made of porous shaped body.
Kynoar adopts immersion precipitation to prepare microporous barrier more at present, and the polymer solution concentration scope is between 8%-40%.The too low film-strength of solution concentration is poor, and the too high then polymer dissolution of concentration is not in good state.The solvent that adopts has dimethyl formamide (DMF), dimethylacetylamide (DMAc), dimethyl sulfoxide (DMSO) (DMSO), N-methyl arsenic pyrrolidone (NMP) isopolarity water-soluble solvent; The mixture of small-molecule substances such as water, acetone, glycerine, ethylene glycol, ethanol, methyl alcohol or itself and aforementioned optimum solvent can be used as the non-solvent coagulating bath; Some little molecule (as LiCL etc.) or polyethylene alkane ketone (PVP), polyethylene glycol big molecules such as (PEG) are often used as the system film additive and add in the preparation liquid; Can control the structure of PVDF microporous barrier by the selection of preparation liquid being formed film forming conditions such as (containing additive), coagulation bath composition and temperature, evaporation time, ambient humidity.Wherein the composition of coagulation bath has a significant impact film properties.Big more such as NaCl concentration in the coagulation bath, film is fine and close more, and porosity is also low more.Ethanol in the coagulating bath is different fully with NaCl to the influence of film morphosis in addition, do not contain ethanol in the coagulation bath, when having only water, easily form finger, increase along with ethanol content in the coagulation bath, corresponding prolongation hardening time of polymer helps the formation of spongelike structure when carrying out the mass transfer exchange.General when the solubility parameter of precipitating reagent changes from small to large, gradually excessively to finger, at the transition point place of two kinds of structures half and half, porosity and average pore size all are in minimum of a value to the form of film from spongelike structure.
The PVDF milipore filter not only is directly used in water treatment, environmental protection and biochemical field of medicaments, can also be used to prepare the support membrane of compounding permeation vaporizing film, composite nanometer filtering film and complex reverse osmosis membrane.Milipore filter as support membrane should have less surface holes and the good hole, cross section of permeability, is beneficial to improve the performance of composite membrane.
Summary of the invention
The invention provides the preparation method of a kind of hole density gradient structural polyvinylidene fluoride flat plate ultrafiltration membrane.The milipore filter shrinkage factor that obtains is low, has superior stretch-proof, shock resistance.
A kind of preparation method of vinylidene difluoride planar ultrafiltration membrane with gradient structure comprises the steps:
(1) Kynoar and additive are dissolved in the phosphoric acid ester solvent under 110～140 ℃, are placed to gel state in room temperature then, under solution temperature, placed 1～5 hour again, in 80～90 ℃ of insulations 1～5 hour, make preparation liquid at last;
(2) blade coating after preparation liquid filtration, the vacuum defoamation was placed in air 10～120 seconds on nonwoven;
(3) will scrape the nonwoven that scribbles preparation liquid at last and immerse in the coagulating bath,, form milipore filter through low temperature gel and two processes of high temperature gel.
Described Kynoar intrinsic viscosity is 0.8～1.7dl/g
In preparation method's the step (1), described preparation liquid mass percent consists of:
Kynoar 10-25%
Additive 0-10%
Phosphoric acid ester solvent 65-90%
The preferred mass percent of preparation liquid consists of:
Polymer 16-21%
Additive 1-6%
Phosphoric acid ester solvent 73-83%
In preparation method's the step (1), described phosphoric acid ester solvent is triethyl phosphate (TEP); Described additive is water, phosphoric acid, small molecular alcohol or LiCL.
Described coagulating bath is deionized water or contains a kind of deionized water solution among system membrane solvent, surfactant or the NaCl.
Low temperature gelling temp described in preparation method's the step (3) is 5～30 ℃, and the time is 0.5～3 hour, and the high temperature gel temperature is 35～60 ℃, and the time is 2～24 hours.
The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
This patent is the fact of macromolecule concentrated solution based on preparation liquid in essence, adopt to immerse the gel phase conversion method, a class milipore filter of the coagulation bath Processing of Preparation by two temperature.For characteristics of the present invention can better be described, " gradient-structure " defined, according to the present invention, the PVDF milipore filter is made up of same chemical substance, its surface is a porous, and the PVDF by crystallization forms near the subgrade on top layer, and subgrade is formed to the PVDF of bottom by indefiniteness; The hole, cross section of film increases gradually from little, and connects mutually.Because like this film of gradient is made up of crystalline portion and amorphous fraction, has good mechanical property, resistance to pressure preferably, less shrinkage.The density and gradient sectional porous ultrafiltration membrane of Zhi Zuoing for a better understanding of the present invention can be referring to accompanying drawing 1,2 and 3.
The invention has the advantages that: the vinylidene difluoride planar ultrafiltration membrane with gradient structure that the inventive method makes can directly apply to the ultra-filtration and separation field, also can be used as support membrane and prepares various composite membranes.By the polyvinylidene fluoride (PVDF) ultrafiltration membrane of this method preparation, be the partially crystallizable layer near the film surface, lower floor is the amorphous layer of network-like pore structure, the shrinkage factor of film is low, the water flux height.
Description of drawings
Fig. 1 is the gradient PVDF milipore filter cross section structure figure of the inventive method preparation;
Fig. 2 be among Fig. 1 gradient PVDF milipore filter near the structure chart of upper epidermis;
Fig. 3 is the approaching structure chart on top layer down of gradient PVDF milipore filter among Fig. 1.
The specific embodiment
Under 110 ℃, 16g Kynoar and 1g lithium chloride are dissolved among the 83gTEP, be placed to gel state in room temperature then, placed 5 hours down in 110 ℃ again, in 90 ℃ of insulations 5 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 10 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 30 ℃, and the time is 0.5 hour; High temperature gel stage gelling temp is 60 ℃, and the time is 24 hours.Obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 2
Under 140 ℃, the 25g Kynoar is dissolved among the 75gTEP, be placed to gel state in room temperature then, placed 1 hour down in 140 ℃ again, in 80 ℃ of insulations 1 hour, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 120 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 10 ℃, and the time is 5 hours; High temperature gel stage gelling temp is 35 ℃, and the time is 2 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 3
Under 130 ℃, the 20g Kynoar is dissolved in 1g water and the 79gTEP mixed solution, be placed to gel state in room temperature then, placed 1 hour down in 130 ℃ again, in 80 ℃ of insulations 3 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 30 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 5 hours; High temperature gel stage gelling temp is 40 ℃, and the time is 12 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 4
Under 120 ℃, 20g Kynoar and 4g glycerine are dissolved among the 76gTEP, be placed to gel state in room temperature then, placed 3 hours down in 120 ℃ again, in 85 ℃ of insulations 3 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 60 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 4 hours; High temperature gel stage gelling temp is 50 ℃, and the time is 8 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 5
Under 120 ℃, with the 20g Kynoar with in 2g water and 78gTEP mixed solution, be placed to gel state in room temperature then, placed 3 hours down in 120 ℃ again, in 85 ℃ of insulations 3 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 60 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 4 hours; High temperature gel stage gelling temp is 50 ℃, and the time is 8 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 6
Under 130 ℃, 20g Kynoar and 2g glycerine are dissolved among the 78gTEP, be placed to gel state in room temperature then, placed 3 hours down in 130 ℃ again, in 85 ℃ of insulations 2 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 20 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 4 hours; High temperature gel stage gelling temp is 40 ℃, and the time is 6 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 7
Under 130 ℃, 20g Kynoar and 3g phosphoric acid are dissolved among the 77gTEP, be placed to gel state in room temperature then, placed 3 hours down in 130 ℃ again, in 85 ℃ of insulations 2 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 40 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 5 hours; High temperature gel stage gelling temp is 50 ℃, and the time is 6 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Embodiment 8
Under 120 ℃, 21g Kynoar and 6g glycerine are dissolved among the 73gTEP, be placed to gel state in room temperature then, placed 3 hours down in 120 ℃ again, in 90 ℃ of insulations 5 hours, make preparation liquid at last; Blade coating after preparation liquid filtration, the vacuum defoamation was placed 30 seconds in air on nonwoven; To scrape the nonwoven that scribbles preparation liquid at last and immerse in the deionized water coagulating bath, low temperature gel phase gelling temp is 15 ℃, and the time is 5 hours; High temperature gel stage gelling temp is 60 ℃, and the time is 9 hours, has obtained the milipore filter of gradient-structure.The gained film is placed on for a long time in the distilled water and preserves until use, or soaks in distilled water after 5 days, uses soaked in absolute ethyl alcohol 20 hours, dries in air.
Claims (6)
1, a kind of preparation method of vinylidene difluoride planar ultrafiltration membrane with gradient structure comprises the steps:
(1) Kynoar and additive are dissolved in the phosphoric acid ester solvent under 110～140 ℃, are placed to gel state in room temperature then, under solution temperature, placed 1～5 hour again, in 80～90 ℃ of insulations 1～5 hour, make preparation liquid at last; Described Kynoar intrinsic viscosity is 0.8～1.7dl/g;
(2) blade coating after preparation liquid filtration, the vacuum defoamation was placed in air 10～120 seconds on nonwoven;
(3) will scrape the nonwoven that scribbles preparation liquid at last and immerse in the coagulating bath,, form the gradient-structure milipore filter through low temperature gel and two processes of high temperature gel.
2, preparation method as claimed in claim 1 is characterized in that: described preparation liquid mass percent consists of:
Kynoar 16-21%
Additive 1-6%
Phosphoric acid ester solvent 73-83%.
3, preparation method as claimed in claim 1 or 2 is characterized in that: described phosphoric acid ester solvent is a triethyl phosphate.
4, preparation method as claimed in claim 1 or 2 is characterized in that: described additive is water, phosphoric acid, small molecular alcohol or LiCL.
5, preparation method as claimed in claim 1 is characterized in that: described coagulating bath is a deionized water.
6, preparation method as claimed in claim 1 is characterized in that: described low temperature gel process gelling temp is 5～30 ℃; High temperature gel process gelling temp is 35～60 ℃.
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| CN102061049B (en) * | 2010-11-30 | 2013-03-27 | 天津工业大学 | Temperature sensitive polyvinylidene fluoride gel film and preparation method thereof |
| CN102002835B (en) * | 2010-12-10 | 2012-06-13 | 绍兴圣世机械有限公司 | Composite membrane machine for manufacturing flat membrane |
| CN102179189A (en) * | 2011-04-01 | 2011-09-14 | 河北科技大学 | Preparation method of pollution-resisting polyvinylidene fluoride ultrafiltration membrane |
| CN103981659B (en) * | 2014-05-08 | 2016-01-20 | 浙江圣世机械有限公司 | A kind of flat membrane compounding production equipment |
| CN105854624A (en) * | 2016-05-09 | 2016-08-17 | 天津工业大学 | High-water-flux polymer separation film |
| CN108744977A (en) * | 2018-06-29 | 2018-11-06 | 安得膜分离技术工程(北京)有限公司 | Ultrafiltration membrane and preparation method thereof |
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Non-Patent Citations (4)
| Title |
|---|
| 制膜条件对PVDF膜形态结构的影响. 陆茵，陈欢林，李伯耿.功能高分子学报，第15卷第2期. 2002 |
| 制膜条件对PVDF膜形态结构的影响. 陆茵，陈欢林，李伯耿.功能高分子学报，第15卷第2期. 2002 * |
| 添加剂对PVDF相转化过程及膜孔结构的影响. 陆茵，陈欢林，李伯耿.高分子学报，第5期. 2002 |
| 添加剂对PVDF相转化过程及膜孔结构的影响. 陆茵，陈欢林，李伯耿.高分子学报，第5期. 2002 * |
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Assignee: Fuyang Meiyiweier Environmental Protection Equipment Co., Ltd. Assignor: Zhejiang University Contract record no.: 2011330000242 Denomination of invention: Method for producing vinylidene difluoride planar ultrafiltration membrane with gradient structure Granted publication date: 20091028 License type: Exclusive License Open date: 20071121 Record date: 20110411 |
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