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Preparation method for beta crystal phase polyvinylidene fluoride hollow fiber porous membrane

The technology of polyvinylidene fluoride and polyvinylidene fluoride resin is applied in the field of preparation of β-crystalline polyvinylidene fluoride hollow fiber porous membrane, which can solve the problems of affecting the strength of PVDF membrane and restricting the development of PVDF microporous membrane technology, and achieves the Conducive to full transformation, reducing post-processing procedures and reducing the possible effect of broken wires

Active Publication Date: 2009-01-14
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the porous membrane prepared by the TIPS method, PVDF mainly exists in the α crystal form, and there are a large number of spherulites in the microporous membrane, which affects the strength of the PVDF membrane to a large extent, and restricts the preparation of PVDF micropores by the TIPS method. Further development of membrane technology

Method used

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Examples

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Effect test

preparation example Construction

[0027] The preparation method of the polyvinylidene fluoride porous membrane of the present invention is carried out according to the following steps:

[0028] 1) Mix the polyvinylidene fluoride resin with the diluent; the mass percentage of the polyvinylidene fluoride resin in the mixture is 15-75%;

[0029] 2) Put the mixture of step 1) into a high-temperature stirred tank, heat up to 140°C ~ 220°C to form a homogeneous polymer solution, and let it stand for defoaming;

[0030] 3) Extruding the homogeneous polymer solution obtained in step 2) and the liquid forming the internal cavity of the fiber through a double-tube die, and directly immersed in a cooling liquid to cool and solidify into a hollow fiber membrane;

[0031] 4) Perform liquid bath stretching on the hollow fiber membrane obtained in step 3);

[0032] 5) Anneal the hollow fiber membrane obtained in step 4);

[0033] 6) Winding the hollow fiber membrane obtained in step 5);

[0034] 7) Use an alcohol or ether extrac...

Embodiment 1

[0044]Combine polyvinylidene fluoride resin with a weight average molecular weight of 300,000 and benzophenone, whose components are polyvinylidene fluoride resin with a weight percentage of 35% and benzophenone with a weight percentage of 65%, and put them in Heat in a high temperature stirring tank to 200°C, stir and mix uniformly to form a homogeneous polymer solution, and let it stand for 24 hours. Then, the homogeneous polymer solution and the core liquid glycerin are extruded through a double-pipe die and directly immersed in a cooling liquid bath at 80° C. to make the solution phase solidify into a film. The cooling liquid bath is a water bath. The solidified hollow fiber membrane is stretched with three-stage hot water, the temperature of the first-stage hot-water drafting device is 70℃, and the temperature of the third-stage hot-water drafting device is 90℃, between adjacent hot-water drafting devices The temperature gradient of the hollow fiber membrane is 10℃, and the t...

Embodiment 2

[0047] Combine polyvinylidene fluoride resin with a weight average molecular weight of 200,000 and benzophenone, whose components are polyvinylidene fluoride resin with a weight percentage of 35% and benzophenone with a weight percentage of 65%, and put them in Heat in a high-temperature stirring tank to 180°C, stir and mix uniformly to form a homogeneous polymer solution, and let it stand for 24 hours. Then, the homogeneous polymer solution and the core liquid glycerin are extruded through a double-pipe die and directly immersed in a cooling liquid bath at 80° C. to make the solution phase solidify into a film. The cooling liquid bath is a water bath. The assimilated hollow fiber membrane is stretched with three-stage hot water, the temperature of the first-stage hot-water drafting device is 70℃, and the temperature of the third-stage hot-water drafting device is 90℃, between adjacent hot-water drafting devices The temperature gradient of the hollow fiber membrane is 10℃, and the...

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Abstract

The invention provides a preparation method of a beta crystalline phase polyvinylidene fluoride hollow fibrous membrane, relating to a membrane manufacture technology of preparing the polyvinylidene fluoride hollow fibrous membrane by a thermally induced phase separation method, in particular to the method of preparing the polyvinylidene fluoride hollow fibrous membrane with the beta crystalline phase of high-flux and high strength by the thermally induced phase separation method. The invention is characterized in that on the basis of a porous membrane prepared by the thermally induced phase separation method, a continuous post-processing method combining stretching and annealing is additionally carried out so as to obtain as much as possible beta crystal form polyvinylidene fluoride intensity; the polyvinylidene fluoride hollow fiber membrane prepared by the method has even distribution of a pore diameter and high water flux; and the product of which the intensity is not processed is improved more greatly.

Description

Technical field [0001] The invention relates to a preparation process of a polyvinylidene fluoride hollow fiber membrane, in particular to a method for preparing a β crystal phase high flux and high strength polyvinylidene fluoride hollow fiber membrane by a thermally induced phase separation method. Background technique [0002] Polyvinylidene fluoride has excellent thermal stability, corrosion resistance, non-combustibility, anti-ultraviolet aging and other properties, and has high strength and wear resistance. Therefore, it has attracted extensive attention in the field of separation membranes in recent years. In terms of microfiltration and ultrafiltration, polyvinylidene fluoride has always been used as a membrane with excellent performance, and its preparation process is mostly non-solvent precipitation gel phase inversion (NIPS). This method has been widely used since the 1980s, including the preparation of flat homogeneous membranes, composite membranes and hollow fiber m...

Claims

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Application Information

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IPC IPC(8): B01D71/34B01D69/08
CPCB01D71/34B01D69/087B01D69/08
Inventor 王晓琳田野林亚凯杨健衷咏
Owner TSINGHUA UNIV
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