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Graded porous polyvinylidene fluoride hollow-fiber composite film and production method thereof

A polyvinylidene fluoride, graded porous technology, applied in the field of water treatment, can solve the problems of high cost, large pore size, cumbersome process, etc., and achieve the effects of simple and controllable production process, low manufacturing cost and fast transmission rate

Inactive Publication Date: 2018-05-29
ZHEJIANG CHANGXING CREFLUX MEMBRANE TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the separation membrane manufacturing method using polyvinylidene fluoride resin as a raw material, thermally induced phase separation (Thermally induced phase separation, TIPS) has become a research hotspot, although this method is more traditional than the traditional nonsolvent induced phase separation (Nonsolvent induced phase separation, NIPS) has high strength and high permeation flow rate, but high cost, large pore size and poor anti-pollution performance
For example, in the patent (CN 103857462 A) published by LG Electronics Co., Ltd., polyvinylidene fluoride, polyetherimide and weak solvent γ-butyrolactone, cyclohexanone, etc. are blended to form a film by the TIPS method and stretched later. A porous polyvinylidene fluoride hollow fiber membrane has been produced, the inner and outer surfaces of the membrane are highly porous, and pore fouling is prone to occur during actual use
Asahi KASEI also used the TIPS method to prepare a durable polyvinylidene fluoride hollow membrane (CN1458859 A). Ethylene has a porous structure, but in the production process, there are operations of chemically extracting inorganic particles and subsequent hydrophilization treatment, and the process is cumbersome
Toray (TORAY) has combined the respective advantages of NIPS and TIPS to produce a double-layer polyvinylidene fluoride ultrafiltration membrane, which uses the TIPS method to form an internal porous support layer and the NIPS method to form a hydrophilic membrane. The external active separation layer of polyvinylidene fluoride constitutes a double-layer structure of a dense separation layer and a porous support layer, but it has the disadvantage of high manufacturing cost

Method used

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  • Graded porous polyvinylidene fluoride hollow-fiber composite film and production method thereof
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  • Graded porous polyvinylidene fluoride hollow-fiber composite film and production method thereof

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Embodiment 1

[0033] A hierarchically porous polyvinylidene fluoride hollow fiber composite membrane, as attached figure 1 And attached Figure 6 As shown in the cross-sectional schematic diagram and the cross-sectional electron microscope image, it includes a hierarchically porous macroporous intermediate layer and an outer separation layer and an inner separation layer covering both sides of the macroporous intermediate layer. The three-layer structure is integrally formed of the same material, and the adjacent two layers of pores are connected. , the outer separation layer and the inner separation layer are denser than the macroporous middle layer, the thickness of the spongy body in the outer separation layer is 100 µm, and the thickness of the spongy body in the inner separation layer is 20 µm. The sponge body of the outer separation layer and the sponge body of the inner separation layer have an asymmetric structure, and their pores are honeycomb or columnar. Increased and highly conne...

Embodiment 2

[0042] Other parts are the same as in Example 1, except that the outer diameter of the hollow fiber composite membrane is about 1400 μm, and the wall thickness is about 300 μm, as shown in the attached Figure 8 The cross-section shown at 200 times magnification shows that the middle layer of the membrane is micron-scale macropores, while the inner and outer end surfaces are a hierarchical porous structure of a slightly dense sponge body, which was tested under a pressure of 0.1 MPa at a total length of 100 cm. The pure water flux at 25°C is 730 L / (m2h), the porosity of the membrane filament is 85 Vol.%, and the bubble point pressure of the membrane is 0.55 MPa in the standard wetting liquid Porefil test of 16 dyn / cm. Pressure ≥ 0.8 MPa. The water contact angle of the wet film after drying is 65°, the tensile breaking strength of the film is 19 MPa, and the crystallinity is 48%.

[0043] Polyvinylidene fluoride resin (Sanaifu 904), organic polar solvent N-methylpyrrolidone (N...

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Abstract

The invention relates to the technical field of water treatment and particularly relates to and discloses a graded porous polyvinylidene fluoride hollow-fiber composite film. The graded porous polyvinylidene fluoride hollow-fiber composite film comprises a graded porous macroporous middle layer, an outer separation layer and an inner separation layer which cover the two sides of the macroporous middle layer, wherein the three-layer structure is integrally made from the same material, pores of adjacent two layers communicate with one another, and structures of the outer separation layer and theinner separation layer are denser than that of the macroporous middle layer. The invention further discloses a production method of the composite film. The method comprises the steps: (1) preparing apolyvinylidene fluoride casting solution; (2) subjecting the casting solution to composite forming, so as to prepare complex type hollow fibers; (3) carrying out air spacing, then, carrying out water-bath coagulating forming, and carrying out traction winding, thereby obtaining the polyvinylidene fluoride hollow-fiber composite film. According to the graded porous polyvinylidene fluoride hollow-fiber composite film and the production method thereof, disclosed by the invention, the graded porous polyvinylidene fluoride hollow-fiber composite film has the advantages of small pore size, high flow rate, high strength and pollution resistance. The production method has the advantages that production procedures are simple and controllable, and the production cost is low.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a hierarchically porous polyvinylidene fluoride hollow fiber composite membrane and a manufacturing method thereof. Background technique [0002] my country is a country short of water. The sustainable development of society, ecology and the health and safety of people depend on water treatment and purification technology. Polyvinylidene fluoride (PVDF) hollow fiber membranes are widely used in industrial sewage treatment, municipal sewage treatment, food industry and other fields due to their excellent physical and chemical properties, high packing density and reverse cleaning. Recently, PVDF hollow membranes with low cost, high strength, small pore size, high permeation flow rate, and anti-fouling are increasingly in demand. [0003] In the separation membrane manufacturing method using polyvinylidene fluoride resin as a raw material, thermally induced phase separation...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D69/12B01D69/08B01D69/02B01D71/34B01D67/00
CPCB01D67/0011B01D69/02B01D69/08B01D69/085B01D69/12B01D71/34B01D2325/021B01D2325/022B01D2325/026B01D2325/36
Inventor 杨永红沈红梅张星星包进锋李芸芳周凌跃张多鹏
Owner ZHEJIANG CHANGXING CREFLUX MEMBRANE TECH CO LTD
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