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Polyvinylidene fluoride separation membrane and its preparation method

A technology of polyvinylidene fluoride and polyvinylidene fluoride resin, which is applied in the field of design and preparation of polyvinylidene fluoride separation membranes and its preparation, can solve the problems of poor mechanical strength of membrane filaments, large investment in equipment, complex processes, etc., and achieve improved processing Fluidity, improvement of processing lubricity, beneficial effect of heat conduction

Inactive Publication Date: 2012-11-07
吕晓龙
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, it has been found in practical applications that one of the problems of the polyvinylidene fluoride hollow fiber membrane prepared by the above method is that there are large voids in the weave structure of the separation membrane section, resulting in poor mechanical strength of the membrane filaments. Broken wire problem is serious
[0004] Polyvinylidene fluoride melt processing is used to prepare separation membranes. The melt extrusion temperature needs to be about 50°C higher than the melting point of the polymer, and the processing temperature is generally about 250°C. The requirements for film-making equipment are high, and in order to improve the processing fluidity of materials , the plasticizers added are generally non-water-soluble chemical reagents, which need to be extracted after the separation membrane is formed, resulting in complicated processes and large investment in equipment

Method used

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preparation example Construction

[0019] The preparation method of the present invention mainly adopts polyvinylidene fluoride resin, of course, it is not limited to this kind of material, and the preparation method can also be applied to other powdery polymer resins, such as polyethylene, polypropylene, polysulfone, polyethersulfone, etc. Commonly used polymer lipids for separation membranes. The polyvinylidene fluoride resin used in the present invention is commercially available general-purpose polyvinylidene fluoride homopolymer or polyvinylidene fluoride copolymer, and injection molding and molding type polyvinylidene fluoride resins can be used. The polyvinylidene fluoride copolymer is a copolymer containing not less than 60% of vinylidene fluoride repeating units. The content of the polyvinylidene fluoride resin in the separation membrane molding composition is 30-80 wt% (mass percentage, the same below), preferably 35-65 wt%.

[0020] Compared with the general plastic melt extrusion processing, the se...

Embodiment 1

[0032] Mix 78wt% of polyvinylidene fluoride resin (Solef 6010, the same below) and 22wt% of propylene glycol in a high mixer at room temperature, and use a twin-screw extruder to form a film. Water is used in the cooling and solidifying tank, compressed air is passed into the core of the tube-type film-making nozzle, and the twin-screw extrusion temperature is 170°C. The pulling speed of the hollow membrane is 50m / min. A polyvinylidene fluoride hollow porous membrane was obtained, with an inner diameter of 1.60 mm, a wall thickness of 0.30 mm, a burst pressure of 0.93 MPa, and an initial pure water permeation flux of 370 L / m 2 ·h0.1MPa 20℃, membrane separation pore size 0.10μm.

Embodiment 2

[0034] Mix 59wt% of polyvinylidene fluoride resin, 20wt% of polytetrafluoroethylene resin (material diameter 25 μm), and 21wt% of propylene glycol in a high-temperature machine at room temperature, and use a twin-screw extruder to form a film. Water is used in the cooling and solidifying tank, compressed air is passed into the core of the tube-type film-making nozzle, and the twin-screw extrusion temperature is 170°C. The pulling speed of the hollow membrane is 20m / min. A polyvinylidene fluoride hollow porous membrane was obtained, with an inner diameter of 0.90 mm, a wall thickness of 0.25 mm, a burst pressure of 0.84 MPa, and an initial pure water permeation flux of 650 L / m 2 ·h0.1MPa 20℃, membrane separation pore size 0.20μm.

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PUM

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Abstract

A polyvinylidene fluoride separation membrane comprises the following membrane preparation complex composition: by weight, 30-80% of a polyvinylidene fluoride resin or polyvinylidene fluoride copolymer; 20-70% of a water-soluble diluent; 0-50% of teflon powder particles; 0-30% of hydrophilic polymer; and 0-30% of inorganic particles. The invention also provides a preparation method of the polyvinylidene fluoride separation membrane. According to the preparation method, a sinter moulding technology is adopted, and a single screw extruder or double screw extruder (blending) are used for continuous extrusion, wherein the extrusion temperature is 140-180 DEG C. According to the invention, a solvent of the polyvinylidene fluoride resin is not required, cross-section structure of the separation membrane is uniform without large voids. Simultaneously, heating is not required to completely melt the polyvinylidene fluoride resin, the separation membrane requires low moulding temperature, and the requirement on separation membrane preparation equipment is low.

Description

technical field [0001] The invention relates to the preparation of a separation membrane and a preparation method thereof, and is especially designed to prepare a polyvinylidene fluoride separation membrane and a preparation method thereof. Background technique [0002] The formation mechanism of the existing polyvinylidene fluoride separation membranes is mostly solution phase transfer film formation, that is, the film-forming polymer, organic solvent, and pore-forming agent are mixed in a certain proportion, and after being dissolved evenly, they enter the coagulant phase, and the polymer due to the phase transfer and precipitate into a polymer separation membrane. In the Chinese invention patent ZL95117497.5, the inventor studied various film-making additives, and adjusted the metastable structure of the casting film liquid by adjusting the ratio of polymers, solvents, high-molecular pore-forming agents and low-molecular non-solvents , so that the spinning casting soluti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34B01D67/00
Inventor 吕晓龙
Owner 吕晓龙
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