CN106975367A - Ethylene tetrafluoroethylene copolymerized macromolecule microporous barrier and preparation method thereof - Google Patents

Abstract

The invention discloses an ethylene-tetrafluoroethylene copolymerized polymer (ETFE) microporous membrane and a preparation method thereof. The preparation steps of the ETFE microporous membrane are: (1) ETFE pellets and calcium carbonate CaCO ₃ powder are blended and extruded at high temperature, cut and granulated; (2) ETFE/CaCO ₃ blended pellets are pressed into a film at high temperature; (3) ) extraction method to dissolve and remove CaCO ₃ in the ETFE/CaCO ₃ blend membrane; (4) wash and dry to obtain the ETFE microporous membrane. The ETFE microporous membrane prepared by the invention can regulate the size _of the ETFE micropores by selecting CaCO3 powders with different particle sizes. The ETFE microporous membrane prepared by the invention has the advantages of high temperature resistance, organic matter resistance, pollution resistance, and acid and alkali resistance, and can be used to treat oil field reinjection water with complex water quality and difficult treatment.

Description

Ethylene-tetrafluoroethylene copolymerized polymer microporous membrane and preparation method thereof

technical field

The invention relates to the research field of microporous membranes, in particular to an ethylene-tetrafluoroethylene copolymerized polymer microporous membrane and a preparation method thereof.

Background technique

Petroleum is the most important energy source for human beings. In the process of oil exploitation, in order to enhance the recovery rate of crude oil, a large amount of water needs to be injected into the oil well; at the same time, formation associated water will also be produced in the process of oil production. In order to obtain qualified petroleum products, it is necessary to separate the associated water and injection water from the oil. The water produced by the separation still contains a certain amount of oil, gas and other solid or liquid impurities. Water is called oily sewage, and the impurities in it include suspended solids, oil, dissolved substances (low molecular weight organic matter and inorganic salts, dissolved gas) and so on. Due to the lack of water resources, oilfields generally treat oil production sewage and reinject it underground, but it has high reservoir damage, strong corrosion and certain scaling. Therefore, a key point in the process of water injection production The problem: preventing the injected water from causing damage to the formation.

Membrane separation technology uses the selective permeability of the membrane to separate and purify the technology. The driving force of the process is mainly the pressure difference on both sides of the membrane; the conditions are mild and the separation accuracy is high, the most ideal separation technology; the membrane separation technology is extremely developed Potential oily wastewater treatment method.

The characteristics of oil extraction wastewater are: high oil content, high chemical oxygen demand, high salinity, easy to scale, contain a large number of suspended solid microorganisms, high water temperature, complex water quality, and difficult to treat. Therefore, the treatment of oil extraction wastewater has relatively high requirements for membranes, especially membrane materials: high temperature resistance, organic matter resistance, pollution resistance, acid and alkali resistance, etc.

ETFE, ethylene-tetrafluoroethylene copolymer polymer, the strongest fluoroplastic, while maintaining the good heat resistance, chemical resistance and electrical insulation properties of polytetrafluoroethylene PTFE, it also has great radiation resistance and mechanical properties. The degree of improvement, its impact resistance, hardness, cold flow resistance and creep resistance are better than PTFE and FEP, and can be processed by thermoplastic molding methods, and the dimensional stability of the parts is comparable to that of nylon or polyoxymethylene. ETFE film is a transparent building material with superior quality. Since the advent of ETFE material, countries such as the United States and Japan have vigorously developed ETFE application research and expanded the application range of ETFE material. In recent years, ETFE membranes grafted with acidic groups/basic groups to prepare proton exchange membranes/anion exchange membranes have attracted the attention of some scholars as a substitute for Nafion membranes for fuel cells or vanadium redox flow batteries. At present, there are few research reports on ETFE in China, and there are only paper reports from several universities such as Tongji University and Shanghai University, which are in their infancy.

ETFE is a crystalline polymer with a crystallinity of 50%~60%. It has good thermal stability and can be used for a long time at -60°C~150°C. The short-term use temperature can reach 230°C, and the decomposition temperature is above 300°C; Self-extinguishing; in addition, ETFE has good mechanical properties, excellent dielectric properties, friction resistance, and chemical corrosion resistance. From the point of view of material performance, ETFE is a very potential microporous membrane material, but the solubility parameter of ETFE is very low, only 13.8 MPa ^1/2 , it is difficult to have a suitable solvent, and the melting point of ETFE is relatively high, resulting in ETFE microporous Membrane preparation is difficult, so no one cares about it so far.

The invention adopts a new method to prepare the ETFE microporous membrane, which has the advantages of high temperature resistance, self-cleaning, resistance to organic matter, etc., and is applicable to sewage treatment with complex water quality such as oil recovery sewage.

Contents of the invention

The purpose of the present invention is to disclose an ethylene-tetrafluoroethylene copolymer (ETFE) microporous membrane and its preparation method. The microporous membrane is prepared by using ETFE with high temperature resistance, organic matter resistance, pollution resistance, and acid and alkali resistance as the membrane material. , can be used to deal with complex water quality, refractory oilfield reinjection water, etc.

Method of the present invention adopts following technical scheme to realize:

(1) Blend ETFE resin and calcium carbonate CaCO ₃ powder in an extruder, extrude continuous fibers at high temperature from the extruder, and cut and granulate the obtained fibers with a granulator; (2) Step (1) ) high-temperature pressing of the obtained blended pellets; (3) removing CaCO ₃ from the film obtained in step (2) through concentrated hydrochloric acid extraction; (4) washing and drying the film obtained in step (3).

The weight-average molecular weight of the ETFE resin is between 2×105 and 3×106 million. The content of ETFE resin is 50-95wt%; the content of calcium carbonate is 5-50wt%;

The particle size of the calcium carbonate ranges from 0.01 to 3 μm;

The blending temperature in the extruder is: 200~280°C;

The temperature of the high-temperature lamination is 170-250°C;

The prepared ethylene-tetrafluoroethylene copolymer (ETFE) microporous membrane has a pore diameter of 0.1-10 μm and a membrane thickness of 40-100 μm.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the examples, but the examples of the embodiments do not constitute limitations on the present invention.

Example 1

Add 70wt% ETFE (weight average molecular weight 2.5×10 ⁶ ) and 30wt% calcium carbonate (12,000 mesh) into the twin-screw extruder, the temperature at the feed port of the extruder is 220°C, and gradually heat up to the extrusion temperature of 280°C , melted and kneaded under the condition of 100rpm, extruded in a circular extrusion die, collected after water cooling, and granulated by a granulator.

The ETFE/calcium carbonate blended particles were pressed into a film with a twin-roller machine, the temperature was adjusted to 250° C., and the film thickness was 100 microns. After the diaphragm is smooth and even, lower the temperature to 170°C to remove the diaphragm.

Cut the membrane to the desired size, and extract calcium carbonate with concentrated hydrochloric acid until the weight of the membrane remains unchanged after washing and drying. The obtained porosity is 30%, the pore diameter is 1 micron, and the film thickness is the ETFE microporous membrane of 104 microns.

Example 2

Add 60wt% of ETFE (weight average molecular weight 2.5×10 ⁶ ), 40wt% of calcium carbonate (5000 mesh) into the twin-screw extruder, the temperature at the feed port of the extruder is 220°C, and gradually heat up to the extrusion temperature of 280°C, Melt and knead under the condition of 100 rpm, extrude in a circular extrusion die, collect after water cooling, and granulate with a granulator.

The ETFE/calcium carbonate blended particles were pressed into a film with a twin-roller machine, the temperature was adjusted to 260°C, and the film thickness was set to 50 microns. After the diaphragm is smooth and even, lower the temperature to 170°C to remove the diaphragm.

Cut the membrane to the desired size, and extract calcium carbonate with concentrated hydrochloric acid until the weight of the membrane remains unchanged after washing and drying. The obtained porosity is 40%, the pore diameter is 2.5 microns, and the film thickness is the ETFE microporous membrane of 55 microns.

Example 3

Add 65wt% ETFE (weight-average molecular weight 2.5×10 ⁶ ) and 35wt% calcium carbonate (10,000 mesh) into the twin-screw extruder. The temperature at the feed port of the extruder is 220°C, and the temperature is gradually raised to the extrusion temperature of 280°C. , melted and kneaded under the condition of 80rpm, extruded in a circular extrusion die, collected after water cooling, and granulated by a granulator.

The ETFE/calcium carbonate blended particles were pressed into a film with a twin-roller machine, the temperature was adjusted to 260°C, and the film thickness was set to 100 microns. After the diaphragm is smooth and even, lower the temperature to 170°C to remove the diaphragm.

Cut the membrane to the desired size, and extract calcium carbonate with concentrated hydrochloric acid until the weight of the membrane remains unchanged after washing and drying. The obtained porosity is 35%, the pore diameter is 1.5 microns, and the film thickness is the ETFE microporous membrane of 100 microns.

Claims (7)

1. a kind of ethylene-tetrafluoroethylene copolymerized macromolecule（ETFE）Microporous barrier, it is characterized in that high temperature resistant, resistance to organic matter, antipollution, Acid and alkali-resistance, can be complicated for water quality treatment, intractable oil field reinjection water etc..

2. ethylene-tetrafluoroethylene copolymerized macromolecule（ETFE）The preparation method of microporous barrier, specifically includes following steps：

（1）By ETFE resins and calcium carbonate CaCO₃Powder is blended in extruder, and extruder high temperature extrudes continuous fiber, will The fiber arrived cuts off granulation using comminutor；

（2）By step（1）Obtained blending pellet high temperature press mold；

（3）By step（2）Obtained film removes CaCO by concentrated hydrochloric acid extraction process₃；

（4）By step（3）Obtained film washing drying.

3. preparation method according to claim 2, the step（1）In ETFE resins weight average molecular weight 2 × 10⁵ ~3 × 10⁶Between ten thousand, the content of ETFE resins is 50~95wt%；Calcium carbonate content is 5~50wt%.

4. preparation method according to claim 2, the step（1）In calcium carbonate particle size range be 0.01 ~ 3 μm.

5. preparation method according to claim 2, the step（1）In extruder in blending temperature be 200 ~ 280 DEG C.

6. preparation method according to claim 2, the step（2）In high temperature press mold temperature be 170 ~ 250 DEG C.

7. preparation method according to claim 2, obtained ethylene-tetrafluoroethylene copolymerized macromolecule (ETFE) microporous barrier Aperture be 0.1~10 μm, film thickness be 40 ~ 100 μm.