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Method for producing vinylidene difluoride planar ultrafiltration membrane with gradient structure

A polyvinylidene fluoride and gradient structure technology is applied in the field of preparation of gradient structure polyvinylidene fluoride flat plate ultrafiltration, which can solve the problems of poor membrane strength, low solution concentration, and poor polymer dissolution state, and achieve low shrinkage rate. , the effect of high water flux

Inactive Publication Date: 2007-11-21
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the solution concentration is too low, the film strength will be poor; if the concentration is too high, the polymer will not dissolve well.

Method used

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  • Method for producing vinylidene difluoride planar ultrafiltration membrane with gradient structure
  • Method for producing vinylidene difluoride planar ultrafiltration membrane with gradient structure
  • Method for producing vinylidene difluoride planar ultrafiltration membrane with gradient structure

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Dissolve 16g of polyvinylidene fluoride and 1g of lithium chloride in 83g of TEP at 110°C, then place it at room temperature until it reaches a gel state, then place it at 110°C for 5 hours, and finally keep it at 90°C for 5 hours to prepare the product Membrane liquid: filter the film-making liquid, vacuum degassing, scrape-coat it on the non-woven fabric, and place it in the air for 10 seconds; finally, immerse the non-woven fabric coated with the film-making liquid in a deionized water coagulation bath, and coagulate at a low temperature. In the gel stage, the gel temperature is 30° C., and the time is 0.5 hours; in the high-temperature gel stage, the gel temperature is 60° C., and the time is 24 hours. The ultrafiltration membrane with gradient structure was obtained. The resulting membranes were stored in distilled water for a long time until use, or soaked in distilled water for 5 days, soaked in absolute ethanol for 20 hours, and dried in the air.

Embodiment 2

[0032] At 140°C, dissolve 25g of polyvinylidene fluoride in 75gTEP, then place it at room temperature until it reaches a gel state, then place it at 140°C for 1 hour, and finally keep it at 80°C for 1 hour to make a film-making solution; Filtration of the membrane solution, vacuum defoaming, scrape coating on the non-woven fabric, and place it in the air for 120 seconds; finally, immerse the non-woven fabric coated with the membrane-making solution in a deionized water coagulation bath, and the gel temperature in the low-temperature gel stage In the high-temperature gel stage, the gel temperature is 35° C., and the time is 2 hours, and an ultrafiltration membrane with a gradient structure is obtained. The resulting membranes were stored in distilled water for a long time until use, or soaked in distilled water for 5 days, soaked in absolute ethanol for 20 hours, and dried in the air.

Embodiment 3

[0034] At 130°C, 20g of polyvinylidene fluoride was dissolved in 1g of water and 79g of TEP mixed solution, then placed at room temperature until gel state, then placed at 130°C for 1 hour, and finally kept at 80°C for 3 hours to produce Membrane liquid: filter the film-making liquid, vacuum degassing, scrape-coat it on the non-woven fabric, and place it in the air for 30 seconds; finally, immerse the non-woven fabric coated with the film-making liquid in a deionized water coagulation bath, and coagulate at a low temperature. In the gel stage, the gel temperature was 15°C, and the time was 5 hours; in the high-temperature gel stage, the gel temperature was 40°C, and the time was 12 hours, and an ultrafiltration membrane with a gradient structure was obtained. The resulting membranes were stored in distilled water for a long time until use, or soaked in distilled water for 5 days, soaked in absolute ethanol for 20 hours, and dried in the air.

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Abstract

The invention is concerned with ultra filtration prepare method of poly (vinylidene fluoride) flat with grads structure. Dissolve poly (vinylidene fluoride) and additive into Phosphate solvent at high temperature, scrape and spread the liquid of film making after filtration and removing dunk on non-woven fabrics and set in air for some time, at last immerge the non-woven fabrics into the liquid with some compose to solidification, after the two gel processes of low temperature and high temperature to get the ultra filtration film with grads structure. This kind of ultra filtration film is fit for ultra filtration separation field and to prepare all kinds of multiplex films as supporting film. The part of poly (vinylidene fluoride) ultra filtration film closes to the surface of film is partly crystal layer, the under layer is non- crystal layer with meshwork type hole structure. The shrink ratio of the film is low with ascendant mechanics capability and this invention has simple operation and cheap stuff.

Description

technical field [0001] The invention relates to the field of polymer membrane preparation and membrane separation, in particular to a preparation method of gradient structure polyvinylidene fluoride plate ultrafiltration. Background technique [0002] PVDF is a crystalline polymer with a density of 1.78g / cm 3 , the glass transition temperature is -39°C, the crystallization melting point is 180°C, the decomposition temperature is above 316°C, and it can still maintain good strength at a certain temperature and under pressure. It has excellent anti-corrosion and anti-aging properties. Its film will not be brittle after being placed outdoors for one or twenty years. It has excellent resistance to acids, alkalis, oxidants, ultraviolet rays and aging. It has good chemical stability and is resistant to aliphatic hydrocarbons, alcohols, Organic solvents such as aldehydes have no effect on it. Therefore, polyvinylidene fluoride (PVDF) microfiltration and ultrafiltration membranes ...

Claims

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Application Information

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IPC IPC(8): B01D71/34B01D69/06
Inventor 安全福孙大海王许云陈欢林高从堦
Owner ZHEJIANG UNIV
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