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Asymmetric polyvinylidene fluoride microporous membrane with high intensity and preparation method thereof

A polyvinylidene fluoride, microporous membrane technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve the problems of inability to change pore size gradient and excellent strength unity, and limit the application of PVDF membranes.

Active Publication Date: 2011-09-28
HANGZHOU COBETTER FILTRATION EQUIP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, in all prior art PVDF membranes, the pore size gradient and excellent strength cannot be unified, which limits the application of PVDF membranes.

Method used

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  • Asymmetric polyvinylidene fluoride microporous membrane with high intensity and preparation method thereof
  • Asymmetric polyvinylidene fluoride microporous membrane with high intensity and preparation method thereof
  • Asymmetric polyvinylidene fluoride microporous membrane with high intensity and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Example 1 PVDF microporous membrane with pore size gradient change in the thickness direction

[0022] We configured PVDF polymer HYLAR-461 with a weight content of 13.7%, fluorosurfactant FC-170 of 9.7%, water of 4%, LiCl of 1% and 71.6% of dimethylacetamide (DMAC) as solvent Casting stock solution. At 70°C, use a spatula with a thickness of 300 μm to evenly coat the polymer solution on a glass plate, stay in air with room temperature and humidity of 70% for 5 seconds, and then immerse in a water bath at 60°C for phase separation and solidification. After curing, the membrane was washed with pure water and then immersed in an aqueous solution with a weight content of 2% KOH and 2% hydrogen peroxide for 48 hours to make the membrane hydrophilic. The average pore diameter of the small pore surface of the membrane is about 0.1 μm, the average pore diameter of the large pore surface is about 15 μm, the thickness of the membrane is about 160 μm, the flow rate of water is 7...

Embodiment 2

[0024] Example 2 The PVDF microporous membrane with the pore diameter in the thickness direction increasing gradually and then tending to be consistent

[0025] We configured PVDF polymer HYLAR-461 with a weight content of 18.5%, 3% fluorosurfactant FC-170, 2% water, 0.5% LiCl and 78% dimethylacetamide (DMAC) as solvent Casting stock solution. At 70°C, use a spatula with a thickness of 300 μm to evenly coat the polymer solution on a glass plate, stay in air with room temperature and humidity of 70% for 5 seconds, and then immerse in a water bath at 60°C for phase separation and solidification. After curing, the membrane was washed with pure water and then immersed in an aqueous solution with a weight content of 2% KOH and 2% hydrogen peroxide for 48 hours to make the membrane hydrophilic. The average pore diameter of the small pore surface of the membrane is about 0.3 μm, the average pore diameter of the large pore surface is about 3 μm, the thickness of the membrane is about...

Embodiment 3

[0027] The influence of embodiment 3 polymer concentration

[0028] We configured PVDF polymer HYLAR-461 with a weight content of 12.5%, fluorosurfactant FC-170 with 2.5%, water with 4%, LiCl with 0.5% and 82% dimethylacetamide (DMAC) as solvent Casting stock solution. Then according to the steps of Example 2, we found that finger-shaped macropores appeared in the prepared membrane.

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Abstract

The invention relates to an asymmetric polyvinylidene fluoride (PVDF) microporous membrane with high intensity and a preparation method thereof. Particularly the invention provides a method for preparing the polyvinylidene fluoride microporous membrane by adding a surface active agent, wherein the surface active agent is preferably a fluorocarbon surface active agent. In a non-solvent phase separation process, on the one hand, the surface active agent and polyvinylidene fluoride macromolecules are cross-linked and hybridized, therefore, the crystalline property of the polyvinylidene fluoride is reduced, the liquid-liquid phase separation is promoted, the crystals are effectively prevented from being agglomerated in the film-forming process of the polyvinylidene fluoride, and the intensityis improved; on the other hand, proved by accidental discovery, a thermodynamic mass transport process is changed by adding the surface active agent so that the asymmetric polyvinylidene fluoride microporous membrane can be prepared. The membrane disclosed by the invention is wide in application, such as clearing and filtering of food / beverage, sterilizing and filtering of medical preparation andthe like.

Description

technical field [0001] The invention relates to the technical field of polymer microporous separation membranes. The membrane of the invention has high strength, and the pore size of the membrane has an asymmetric structure in the thickness direction. Background technique [0002] Polymer microporous membrane is a high-tech industry developed abroad in the 1970s, which belongs to the category of membrane separation. Various separation membranes are classified according to the size of the membrane gap, and are usually divided into reverse osmosis membranes, nano-filtration membranes, ultrafiltration membranes, and microporous membranes from small to large. -filtration membrane). In terms of application, reverse osmosis membranes are usually used for seawater desalination, ultrapure water production, etc., nanofiltration membranes are usually used for the removal of low molecular weight and large metal ions such as calcium and magnesium in water, and ultrafiltration membrane...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D67/00B01D69/02B01D71/34
Inventor 卢红星
Owner HANGZHOU COBETTER FILTRATION EQUIP
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