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Method for producing polyvinylidene fluoride porous membrane by using composite thinning agent

A technology of polyvinylidene fluoride and mixed diluent, which is applied in the field of preparation of polyvinylidene fluoride hollow fiber porous membranes, can solve problems such as unsatisfactory membrane structure and performance, and achieve easy control of membrane-making conditions, simple membrane-making process, The effect of excellent performance

Inactive Publication Date: 2008-03-12
TIANJIN MOTIAN MEMBRANE ENG & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for polyvinylidene fluoride materials, due to the difficulty of finding a suitable single diluent, the structure and performance of the prepared membrane are not ideal

Method used

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  • Method for producing polyvinylidene fluoride porous membrane by using composite thinning agent

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preparation example Construction

[0028]The preparation method of the composite diluent of the present invention is: adding a high-temperature-resistant organic non-solvent to the latent solvent of polyvinylidene fluoride to form a composite diluent, and adjusting the compatibility between the composite diluent and polyvinylidene fluoride, that is, according to the solution phase of the system Figure, adjust the phase separation mode of composite diluent and polyvinylidene fluoride high-temperature solution, so that liquid / liquid phase separation occurs, and it is easy to obtain a uniform porous structure.

[0029] Both the surface and the inside of the membrane prepared by the invention have a uniform porous structure, the porosity is 60-85%, and the water permeability of the membrane is 80-1000L.m under the pressure of 0.1MPa and 25°C. -2 .h -1 . The inner diameter and outer diameter of the hollow fiber membrane can be determined by the extrusion rate and winding rate according to different application fiel...

Embodiment 1

[0031] Example 1: Put 25wt% polyvinylidene fluoride, 30wt% dibutyl phthalate, 15wt% diethyl phthalate, and 30wt% dioctyl phthalate in a solvent tank and heat To 220°C, stir and dissolve to form a transparent solution, stand still for degassing for 2 hours, then scrape the film in an environment of 220°C, directly put it in a 20°C water bath to cool and shape, and extract the diluent to form a porous film. The surface and internal structure of the membrane are uniform, and the water flux is 342L.m -2 .h -1 , Porosity 82%.

Embodiment 2

[0037] Example 2: 20wt% polyvinylidene fluoride, 30wt% dibutyl phthalate, 20wt% diethyl phthalate, and 30wt% diisooctyl phthalate are placed in a solvent tank together, Stir and dissolve at 200°C to form a transparent solution, defoam for 2 hours, scrape the film in an environment of 200°C, and directly immerse in an ice-water bath to form a porous film after extracting the diluent. Uniform membrane structure, water flux 1002L.m -2 h -1 , Porosity 83%.

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Abstract

The present invention relates to a manufacture method of a polyvinylidene fluoride multi-pore membrane and comprises a flat membrane and a hollow fiber membrane. The manufacture method is that the polyvinylidene fluoride and a mixed solvent of a plurality of diluents are added into a dissolving tank; the content of the polyvinylidene fluoride is 20wt-40wt percent, and the content of the mixed solvent is 80wt-60wt percent; the polyvinylidene fluoride and the mixed solvent are mixed and dissolved under a high temperature to form a transparent solution, which is extruded out after deaerated; an air section is cooled down in a water bath to form an initial product; then the diluents are extracted to get the multi-pore product.

Description

technical field [0001] The invention relates to a preparation method of polyvinylidene fluoride hollow fiber porous membrane. The porous membrane prepared by the method has uniform structure, better water flux and higher porosity, and can be used for filtration and separation, tap water purification, sewage treatment and reuse, and the like. Background technique [0002] Membrane separation technology is a new type of separation technology that uses the difference in the selective permeability of the membrane to the components in the mixture to achieve separation, purification and concentration. Compared with traditional separation methods, membrane separation technology has the characteristics of simple device, easy operation, energy saving, high separation efficiency, low cost, and remarkable economic benefits. Therefore, the film industry has developed rapidly in recent years, increasing at an annual rate of 14%-15%. In particular, the development of high-performance se...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34
Inventor 李先锋吕晓龙
Owner TIANJIN MOTIAN MEMBRANE ENG & TECH
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