Method for preparing polyvinylidene fluoride micro-porous film with thermal induced phase separation method

A technology of thermally induced phase separation and polyvinylidene fluoride, which is applied in semipermeable membrane separation, chemical instruments and methods, membrane technology, etc., can solve the problems of environmental pollution and high price

Inactive Publication Date: 2012-08-08
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, methyl benzoate has a strong pungent smell, phosphate esters pollute the environment because of phosphorus, organic carbonates and citric acid esters are more expensive, and alcohols are preferred among weak diluents. When the strength of the formed film is only about 3MPa

Method used

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  • Method for preparing polyvinylidene fluoride micro-porous film with thermal induced phase separation method
  • Method for preparing polyvinylidene fluoride micro-porous film with thermal induced phase separation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Add 40g of polyvinylidene fluoride resin with a weight average molecular weight of 350,000 and a mixture of 160g of co-solvent into a stirred tank. The co-solvent is made by mixing benzyl benzoate and dimethyl phthalate, of which 80g benzyl benzoate . Heat to 200 in a stirred tank 。 C, stirring speed is 30r / min, nitrogen protection, heating for 7 hours, degassing becomes a homogeneous solution; 。 Scrape it into a flat film in a high temperature environment of C, cool it naturally, take out the flat film, immerse it in absolute ethanol for 24 hours, then replace it with absolute ethanol, immerse it for another 24 hours, then remove it from absolute ethanol, and dry at room temperature .

[0017] The obtained flat film is observed by electron microscope (liquid nitrogen freezing and quenching) structure, see the electron microscope picture figure 1 , The section is a bi-continuous structure, and the average pore diameter of the membrane pores is about 0.5μm.

Embodiment 2

[0019] Add 100g of polyvinylidene fluoride resin with a weight average molecular weight of 350,000, and a mixture of 100g of co-solvent into the stirred tank. The co-solvent is made by mixing dibutyl sebacate and glyceryl triacetate, among which dibutyl sebacate For 70g. Heat to 180 in a stirred tank 。 C, the stirring speed is 50r / min, nitrogen protection, heating for 7 hours, it is a homogeneous solution; vacuum degassing; the polymer solution is extruded from the annular gap of the spinneret under the action of the gear pump; the extrusion rate is 1ml / s, spraying Wire head temperature is 175 。 C; Injecting cavity gas into the inner hole of the spinneret N 2 Make the extrudate have a hollow structure; N 2 The flow rate of the film-forming fluid is 0.5ml / s; the film-forming fluid and the cavity-forming gas move along the axial direction and gradually become thinner under the action of traction; the film-forming fluid gradually cools in the air environment, and the L-L phase sepa...

Embodiment 3

[0022] Add 60 g of polyvinylidene fluoride resin with a weight average molecular weight of 500 000 and a mixture of 140 g of co-solvent into a stirred tank. The co-solvent is made by mixing benzyl benzoate and dimethyl phthalate. The mass score is 98g. Heat to 200 in a stirred tank 。 C, nitrogen protection, heating for 7 hours, a homogeneous solution; vacuum degassing; the polymer solution is extruded from the annular gap of the spinneret under the action of a gear pump; the extrusion rate is 1ml / s, and the spinneret temperature is 190 。 C; Injecting cavity gas into the inner hole of the spinneret N 2 Make the extrudate have a hollow structure; N 2 The flow rate of the film-forming fluid is 0.5ml / s; the film-forming fluid and the cavity-forming gas move along the axial direction under the action of traction and gradually refine; then the water bath (15 。 C) Curing, this process is accompanied by the volatilization of the diluent to the environment; after curing, the hollow fiber ...

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Abstract

The invention discloses a method for preparing a polyvinylidene fluoride micro-porous film with a thermal induced phase separation method, belonging to the technical field of preparation of a polyvinylidene fluoride micro-porous film. The method comprises the following steps of: mixing a polyvinylidene fluoride resin with a cosolvent consisting of weak and strong action potential solvents, wherein the weak action potential solvent is benzyl benzoate or dibutyl sebacate, and the strong action potential solvent is dimethyl phthalate, monoglyceride or benzophenone; heating for dissolving into a homogeneous mixture; and cooling and scraping into a flat plate film or spinning into a hollow fiber film. The method has the advantages that: by adjusting the mixture ratio of the strong and weak action potential solvents in the cosolvent, the compatibility with PVDF (Polyvinylidene Fluoride) can be adjusted, and the microcellular structure and size of the film can be further controlled. Moreover, a PVDF film prepared with the method has high strength, which can be up to 9.5MPa; and the water flux is high, and can be up to 705 L/(m<2>.bar.h).

Description

Technical field [0001] The invention relates to a method for preparing a polyvinylidene fluoride microporous membrane by a thermally induced phase separation method, and belongs to the technical field of preparation of polyvinylidene fluoride microporous membranes. Background technique [0002] Polyvinylidene fluoride membranes are usually prepared by the NIPS method. This method is caused by the mutual diffusion between the non-solvent in the cooling medium and the solvent in the spinning solution, or the volatilization of the solvent. The cross-section of the membrane is mostly a finger-like pore structure. , The mechanical strength is poor; the pore size of the membrane is not easy to control and the pore size distribution is wide. TIPS membrane has the characteristics of narrow pore size distribution, high porosity, controllable pore size, and high mechanical strength. [0003] The research on the preparation of polyvinylidene fluoride microporous membrane by TIPS method is mo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34B01D69/06B01D69/08B01D67/00
Inventor 李凭力安亚欣吴浩赟常贺英
Owner TIANJIN UNIV
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