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Method for preparing hollow fiber membranes by melt extrusion process

A melt extrusion, fiber membrane technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc. The effect of improved membrane mechanical properties, simple preparation process and good mechanical properties

Inactive Publication Date: 2014-11-19
TIANJIN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the hollow fiber membrane that this method makes is poor in permeability, and flux is little, only 2.15ml / (hr·m 2 mmHg), little significance for industrial implementation

Method used

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  • Method for preparing hollow fiber membranes by melt extrusion process
  • Method for preparing hollow fiber membranes by melt extrusion process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The base film material is cellulose acetate with an acetyl content of 39.8% and a molecular weight of 30,000; PEG with a molecular weight of 6,000 is used as a polymer additive; the composite porogen is 0.01 μm SiO 2 Powder and 0.05 μm LiCl, the former is a water-insoluble porogen, accounting for 30wt% of the total composite porogen, and the latter is a water-soluble porogen, accounting for 70wt% of the total composite porogen. The mass ratio of each component of the film-forming system is: cellulose acetate 40wt%, polymer additive 15wt%, organic additive 0%, composite porogen 45wt%.

[0042] After the cellulose acetate, polymer additives, organic additives and composite porogen are mixed evenly, they are added to a twin-screw extruder, extruded and spun through a hollow fiber spinneret, and the spinning temperature is 180°C to obtain a nascent hollow membrane. Then, the primary hollow membrane is subjected to length-fixing heat treatment, the draft ratio is 2.5 times,...

Embodiment 2

[0045] Cellulose acetate with an acetyl content of 39.8% and a molecular weight of 40,000 is used as the base film material; PEG with a molecular weight of 2,000 is used as the polymer additive; the composite porogen is 0.1 μm SiO 2 Powder and 0.05 μm NaCl, the former is a water-insoluble porogen, accounting for 30wt% of the total composite porogen, and the latter is a water-soluble porogen, accounting for 70wt% of the total composite porogen. The mass ratio of each component of the film-forming system is: cellulose acetate 35wt%, polymer additive 15wt%, organic additive 0%, composite porogen 50wt%.

[0046] After the cellulose acetate, polymer additives, organic additives and composite porogen are mixed evenly, they are added into a twin-screw extruder, extruded and spun through a hollow fiber spinneret, and the spinning temperature is 175° C. to obtain nascent hollow membrane. Then, the primary hollow membrane is subjected to length-fixing heat treatment, the draw ratio is ...

Embodiment 3

[0049] Cellulose acetate with an acetyl content of 41.5% and a molecular weight of 50,000 is used as the base film material; PEG with a molecular weight of 600 is used as a polymer additive; the composite porogen is 0.1 μm SiO 2 Powder and 0.1μm CaCl 2 , the former is a water-insoluble porogen, accounting for 30wt% of the total composite porogen, and the latter is a water-soluble porogen, accounting for 70wt% of the total composite porogen. The mass ratio of each component of the film-forming system is: cellulose acetate 30wt%, polymer additive 15wt%, organic additive 0%, composite porogen 55wt%.

[0050] After mixing the cellulose acetate, polymer additives, organic additives and composite porogen uniformly, put them into a twin-screw extruder, extrude and spin through a hollow fiber spinneret at a spinning temperature of 170°C, and obtain a nascent hollow membrane. Then, the primary hollow membrane is subjected to length-fixing heat treatment, the draft ratio is 1.5 times,...

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Abstract

The invention discloses a method for preparing hollow fiber membranes by a melt extrusion process. The method adopts a membrane formation system consisting of the following components in percentage by weight: 20%-40% of cellulose acetate, 10%-25% of polymeric additives, 0-10% of organic additives, and 40%-60% of a composite porogenic agent, wherein the acetyl content of the cellulose acetate is 38%-41.5%, and the molecular weight is 30000-50000. The method adopts a preparation process comprising the following steps of: uniformly mixing the cellulose acetate and the polymeric additives in proportion, then adding the composite porogenic agent for uniformly mixing, carrying out melt extrusion on the mixture with a double-screw extruder at 150-200 DEG C, processing the extrudate with a hollow spinning pack, and solidifying and shaping the extrudate in water bath to obtain a primary hollow fiber membrane; then performing constant-length heat treatment on the primary hollow fiber membrane, wherein the draft multiple is 1.5-3 times, and the heat treatment temperature is 70-90 DEG C; and finally, extracting and washing the primary hollow fiber membrane to obtain the hollow fiber membrane.

Description

technical field [0001] The invention relates to a membrane preparation technology, in particular to a method for preparing a hollow fiber membrane by a melting extrusion method, and the hollow fiber membrane is a cellulose acetate hollow fiber membrane. Background technique [0002] Cellulose acetate (CA) has been used as a membrane material for a long time. Because of its good hydrophilicity, excellent film-forming performance, and certain biocompatibility, it is widely used in ultrafiltration, nanofiltration (NF), and reverse filtration. Osmosis (RO) and blood filtration etc. At present, there are many research reports on cellulose acetate membrane at home and abroad. E.g: [0003] In 1984, a preparation method of cellulose acetate microporous membrane was disclosed in the meeting of China Society of Seawater Desalination and Water Reuse. In the method, anhydrous ethanol and dichloroethane are used as solvents and additives are added to form a film-forming liquid, which...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D69/08B01D71/16B01D67/00
Inventor 肖长发王恒刘海亮
Owner TIANJIN POLYTECHNIC UNIV