KR20120077011A - Water treatment membrane of poly(ethylenechlorotrifluoroethylene) and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A poly(ethylene chlorotrifluoroethylene(ECTFE))-based water treating separating membrane and a method for manufacturing the same are provided to manufacture the water treating separating membrane at low temperatures and to be used for a long period of time without the reduction of performance. CONSTITUTION: A poly ECTFE water treating separating membrane is manufactured based on a non-solvent induced phase separating method. The inside of the membrane is composed of micro pore layer of a sponge structure. The micro pore layer is formed by a silica micro pore forming agent. The membrane is a flat membrane or a hollow fiber membrane. A method for manufacturing the poly ECTFE water treating separating membrane includes the following: a mixed solution of an ECTFE polymer resin, a micro pore forming agent, and a solvent is prepared; the mixed solution is discharged from a nozzle; lumen forming fluid flows into the nozzle to be discharged in order to form a hollow fiber shape; and the solution from the nozzle is immersed in external condensing liquid in a condensing bath and is solidified.

Description

ECTFE Water Treatment Membrane and Manufacturing Method Thereof {WATER TREATMENT MEMBRANE OF POLY (ETHYLENECHLOROTRIFLUOROETHYLENE) AND MANUFACTURING METHOD THEREOF}

The present invention relates to a polyethylene chlorotrifluoroethylene (hereinafter, abbreviated as "ECTFE") water treatment membranes and a method for preparing the same, and more particularly, prepared by non-solvent induced phase separation, In addition, by introducing a specific pore-forming agent into the mixed solution for the production of the membrane, by inducing pore formation in the membrane to improve the water permeability, when applied as a membrane module for water and wastewater treatment, ECTFE capable of long-term operation without degradation The present invention relates to a water treatment membrane and a method of manufacturing the same.

In recent years, the UF market for water treatment is increasing every year, and UF membranes are currently favored in the market for fluorine-based membranes represented by polyvinylidene fluoride (hereinafter, abbreviated as "PVDF").

However, PVDF resins, which have been proven as suitable materials for water treatment membranes to date, require better chemical stability and performance, and thus, research into the development of membrane materials having a strong resistance to corrosive solutions such as oxidizing agents or species having high pH has not been carried out. It's going on. In particular, in the case of water treatment membranes, a membrane fouling phenomenon called fouling is inevitably involved while obtaining purified production water from contaminated raw water, so that strong resistance to acid and basic environments is required. Since such membrane contamination is usually a phenomenon caused by the adsorption of contaminants in the raw water on the membrane surface, the contamination of the membrane surface increases the pressure applied during filtration and gradually decreases the production quantity, which seriously affects the membrane filtration process.

Therefore, in order to prevent membrane contamination during the process, in a normal water treatment operation process, an aqueous solution including an acid and a basic substance is supplied in a direction opposite to the membrane filtration direction, and the source or surface is contaminated or removed by an acid or basic substance. Perform backwash process.

However, the backwashing process based on the acid and the basic substance removes contaminants and greatly weakens the chemical resistance of the membrane, thereby impairing the durability of the membrane in the long term. In particular, PVDF hollow fiber membranes, which are commonly used as water treatment membrane materials, are very vulnerable to basic solvents, causing yellowing or brittleness, which is a signal of degeneration of membrane properties. Face serious problems of losing.

In order to compensate for this, development of separators of various materials that can replace PVDF materials has been attempted. Among them, researches on membranes using ECTFE polymers are being actively conducted. The Teflon-based material, ECTFE, not only has excellent mechanical, thermal and chemical properties of wear resistance or tensile strength, but also does not change physical properties even in acid and basic environments. It does have the advantage. Therefore, attention has been drawn to the material that can replace the conventional membrane of PVDF material.

US Patent No. 7,247,238 discloses a method for preparing hollow fibers and flat membranes in which ECTFE polymer is prepared by thermally induced phase separation using a uniform solution prepared at a high temperature of 200 ° C. or higher in a solvent such as ethyl citrate and glycerol triacetate. have.

The thermally induced phase separation method is a method of preparing a porous separator by contacting a polymer solution dissolved at a high temperature with a low temperature medium and liquid-solid phase separation and solidification. Since the thermally induced phase separation method needs to maintain a high temperature state, it is necessary to select an appropriate solvent and pore-forming agent that requires more energy than a general membrane manufacturing process and does not volatilize even at high temperature conditions. In addition, when the separation membrane is manufactured using the thermally induced phase separation method, a technique capable of controlling the pore size and the fine skin present on the surface is currently unreachable. In addition, it is vulnerable to safety in the manufacturing process because the separator is manufactured under a temperature condition higher than the general separator manufacturing conditions.

Thus, unlike the method of preparing the porous membrane by the thermally induced phase separation method of contacting the polymer solution dissolved at a high temperature with a low temperature medium and liquid-solid phase separation and solidification, as another method of manufacturing a porous membrane using the ECTFE polymer Non-solvent induced phase in which the polymer is dissolved in a suitable solvent capable of dissolving the polymer and the solvent and the non-solvent are exchanged in the polymer solution to induce solidification after liquid-solid phase separation. separation.

Accordingly, the present inventors have tried to solve the problem of the hollow fiber membrane using the ECTFE polymer prepared by the conventional thermally induced phase separation method, by optimizing the non-solvent induced phase separation method, the pore-forming agent in the mixed solution containing the conventional ECTFE polymer and solvent The present invention was completed by preparing a hollow fiber membrane made of ECTFE material, which significantly improved the water permeability of the porous separator by adding.

It is an object of the present invention to provide an ECTFE water treatment membrane consisting of a sponge-like microporous layer.

Another object of the present invention is to introduce a pore-forming agent in the mixed solution for the preparation of the membrane during the manufacturing process by the non-solvent induced phase separation method to form a fine pores of the sponge structure inside the membrane to improve the water permeability significantly It is to provide a manufacturing method.

In order to achieve the above object, the present invention provides an ECTFE water treatment membrane made of a non-solvent induced phase separation method, consisting of a sponge-like microporous layer.

That is, the present invention provides a water treatment separation membrane having improved water permeability by introducing a silica pore-forming agent into a mixed solution for preparing an ECTFE water treatment separation membrane by micropores of a sponge structure formed inside the separation membrane.

At this time, the ECTFE water treatment membrane of the present invention satisfies the water permeability of 70 L / m ² hr or more, and comprises a flat membrane or hollow fiber membrane form.

In addition, the present invention 1) prepare a mixed solution consisting of 10 to 50% by weight of ECTFE polymer resin, 1 to 30% by weight pore-forming agent and 20 to 89% by weight of the solvent,

2) discharging the mixed solution from a nozzle, and flowing a lumen forming fluid into the nozzle to discharge the mixed solution to form a hollow fiber shape;

3) It provides a method for producing an ECTFE hollow fiber membrane consisting of immersing and solidifying the solution discharged from the nozzle in the external coagulation solution of the coagulation bath.

The mixed solution of step 1) is carried out by maintaining at a temperature of 60 to 200 ℃, it is possible to produce a separation membrane at a lower temperature than the conventional thermal induced phase separation method.

It is preferable to use hydrophilic or hydrophobic fumed silica as the pore-forming agent used in this step 1), and a preferable solvent is N-methylpyrrolidone, dimethylacetamide, triacetin, dibutyl phthalate. And dioctylphthalate. One or a mixture of two or more selected from the group consisting of dioctylphthalate is used.

Further, in the preparation method of the present invention, the lumen-forming fluid of step 2) is preferably diethylene glycol, N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, glycerol and water. It is to use one or a mixture of two or more selected forms, so that the lumen forming fluid is maintained at 10 to 200 ℃ during discharge.

In the step 3), the distance from the nozzle to the surface of the external coagulating solution of the coagulation bath is maintained at 10 to 100 mm.

According to the present invention, it is possible to provide a water treatment separation membrane of ECTFE material, more preferably ECTFE hollow fiber membrane, having improved water permeability.

The ECTFE water treatment membrane prepared according to the present invention can produce a separation membrane at a lower temperature than the conventional thermal induction phase separation method, water permeability is significantly improved compared to the ECTFE hollow fiber membrane prepared by the conventional non-solvent induction phase separation process to treat purified water and wastewater When the membrane is applied to the membrane module, it can be operated for a long time without any deterioration in performance.

In addition, the present invention provides an ECTFE hollow fiber membrane by a non-solvent induced phase separation method, ECTFE hollow fiber membrane by introducing a pore-forming agent into the mixed solution for the preparation of the membrane to induce pore formation in the membrane to significantly improve the water permeability It can provide a manufacturing method of.

1 is an electron scanning microscope photograph of 500 times the cross section of the ECTFE hollow fiber membrane prepared in Example 1 of the present invention,
2 is an electron scanning microscope photograph of a 500 times magnification of a cross section of the ECTFE hollow fiber membrane prepared in Example 2 of the present invention;
3 is an electron scanning microscope photograph of a 500-fold enlarged cross section of the ECTFE hollow fiber membrane prepared in Comparative Example 1 of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides an ECTFE water treatment membrane composed of a sponge-like microporous layer.

1 and 2 are cross-sectional photographs of the water treatment separation membranes prepared in Examples 1 and 2 of the present invention, and it can be seen that they are made of a sponge-like microporous layer. On the other hand, Figure 3 is a cross-sectional photograph of the ECTFE water treatment membrane of Comparative Example 1 prepared by a conventional non-solvent induction phase separation method, without using a pore-forming agent in the manufacturing process, to identify a relatively dense cross-sectional structure Can be.

Sponge-like microporous layer of the present invention is to form a pore inside the separator by introducing a pore-forming agent in the mixed solution for the production of the membrane, the number of 70 L / m ² hr or more by this structural feature Meets permeability.

Based on the embodiment of the present invention, the maximum water permeability of 257.6 L / m ² hr is presented, but as the pore forming agent content increases, the water permeability also increases, thereby increasing the content of the added pore forming agent. By adjusting the water permeation properties of the ECTFE membrane can be controlled.

The ECTFE water treatment separation membrane of the present invention consisting of the sponge-like microporous layer includes a form of a flat membrane or a hollow fiber membrane.

In addition, the present invention provides a method for producing a hollow fiber ECTFE hollow fiber membrane of the water treatment membrane using the ECTFE polymer. More specifically,

1) prepare a mixed solution consisting of 10 to 50% by weight of the ECTFE polymer resin, 1 to 30% by weight of the pore-forming agent and 20 to 89% by weight of the solvent,

2) discharging the mixed solution from the nozzle, flowing a lumen forming fluid into the nozzle,

3) The mixed solution discharged from the nozzle is immersed in the external coagulation solution of the coagulation bath and solidified.

In the method for producing the ECTFE hollow fiber membrane of the present invention, the mixed solution of step 1) is composed of 10 to 50% by weight of ECTF polymer resin, 1 to 30% by weight of pore-forming agent and 20 to 89% by weight of solvent. At this time, if the ECTFE content is less than 10% by weight, while the hollow formation is impossible due to the low viscosity, when the content exceeds 50% by weight, it is difficult to discharge the solution due to the high viscosity of the mixed solution.

In addition, the pore-forming agent is preferably maintained at 1 to 30% by weight in the total mixed solution, if less than 1% by weight, it is impossible to form micropores in the separation membrane, if it exceeds 30% by weight of the mixed solution Due to the high viscosity, hollow fiber molding is impossible.

At this time, the pore-forming agent is to modify the properties of ECTFE, which is the main polymer material of the water treatment membrane of the present invention, or as a material for forming fine pores therein, which must be compatible with ECTFE.

Accordingly, in the present invention, the pore-forming agent is silica, wherein the silica used includes hydrophobic silica or hydrophilic silica, and more preferably fumed silica.

The solvent used in the mixed solution of step 1) of the present invention is not particularly limited as long as it is a solvent capable of uniformly and completely dissolving the polymer and the lumen forming fluid at a temperature of room temperature to 200 ° C., without forming a precipitate. One or a mixture of two or more selected from the group consisting of pyrrolidone, dimethylacetamide, triacetin, dibutyl phthalate and dioctyl phthalate can be used.

The mixed mixture prepared as described above is preferably maintained at a temperature of 60 to 200 ℃, at this time, there should be no formation of precipitates or observation of suspended solids at 60 to 200 ℃ temperature conditions.

In the manufacturing method of the present invention, step 2) is a step of discharging the mixed solution from the nozzle and flowing a lumen-forming fluid into the nozzle. That is, it is possible to obtain a hollow fiber shape in which the lumen is formed by the lumen forming fluid that is in contact with the lumen while the mixed solution is discharged from the nozzle.

Lumen-forming fluid of the present invention is one or a mixture of two or more selected from the group consisting of diethylene glycol, N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, glycerol and water is used Can be. At this time, when used in two or more mixed forms, the solvent is preferably contained in 5 to 95% by weight.

The lumen forming fluid of the present invention is preferably maintained at 10 to 200 ℃ during discharge, in this case, if it is maintained below 10 ℃, it is difficult to form a hollow, if it exceeds 200 ℃, the internal lumen structure is not completely solidified eccentric This occurs, resulting in a defect of the hollow fiber membrane.

Process 3) of the present invention is to immerse the mixed solution discharged in the above step 2) in the external coagulation solution of the coagulation bath, to induce a solvent-non-solvent exchange between the mixed solution and the external coagulation solution, and then to solidify. ECTFE hollow fiber membranes are prepared. At this time, water is used as the external coagulant.

In this step 3), the distance (Air gap) from the nozzle to the surface of the external coagulation solution of the coagulation bath is preferably maintained at 10 to 100 mm. If the air gap is less than 10mm, the polymer is solidified before the pores are formed in the separator, there is difficulty in forming the pores, and if the air gap is maintained at a distance of more than 100mm, the distance between the hollow fiber and the coagulation tank discharged is increased Shaking occurs and this causes eccentricity, which is not preferable because of the failure of the hollow fiber membrane.

After the step 3), it will be understood that the washing process may further include a process of removing organic matter including a solvent remaining inside and outside the membrane of the hollow fiber membrane exposed to the atmosphere from the coagulation solution. At this time, the washing solution is preferably water, the washing time is not particularly limited, it is preferably carried out for at least 1 day or more, 5 days or less.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

≪ Example 1 >

20% by weight of ECTFE (Halar) was mixed with 18% by weight of silica (product name: OX 50) as a pore-forming agent and 62% by weight of solvent N, N-dimethylacetamide (DMAc) to uniformly mix the solution under 140 ° C. Prepared. After removing bubbles in the prepared mixed solution by using a vacuum pump, the mixed solution was flowed into the nozzle maintained at 140 ° C. using a gear pump, and 50 weights of dimethylacetamide (DMAc) was added to the lumen side of the triple nozzle. The hollow formation was induced by flowing a lumen forming body consisting of% and 50% by weight of diethylene glycol at 50 ° C. At this time, the solution discharged from the nozzle was continuously precipitated in a coagulation bath made of water of 90 ℃ to prepare a hollow fiber membrane made of ECTFE material. At this time, the air gap from the spinning nozzle to the surface of the external coagulant (water) in the coagulation bath was 30 mm.

<Example 2>

When preparing the mixed solution of Example 1, using the pore-forming agent to be added in 3% by weight, except that it is prepared in the composition shown in Table 1, it was made in the same manner as in Example 1 made of ECTFE material A hollow fiber membrane was prepared.

&Lt; Comparative Example 1 &

In preparing the mixed solution of Example 1, except that the pore-forming agent was not used, the same procedure as in Example 1 was performed to prepare a hollow fiber membrane made of ECTFE material.

Experimental Example 1 Property Evaluation

For the hollow fiber membrane module prepared in Examples and Comparative Examples, the pure water permeability was measured by the following method. Specifically, pure water at room temperature is supplied to the one side of each hollow fiber membrane module by DEAD-END method at 2.0 atm, and after measuring the amount of water permeated, the unit time, unit membrane area, unit pressure It was converted into sugar permeation amount. The results are shown in Table 1 below.

As shown in Table 1, the ECTFE hollow fiber membrane (FIG. 3) of Comparative Example 1 using a mixed solution without using a pore-forming agent, the pure permeability compared to the ECTFE hollow fiber membrane prepared by containing a pore-forming agent results Showed. That is, as can be seen in Figure 3, the internal structure of the ECTFE hollow fiber membrane of Comparative Example 1 that does not use a pore-forming agent has a relatively very dense structure, Example 1 manufactured using a pore-forming agent and In the inner layer of the ECTFE hollow fiber membrane of Example 2, the micropore shape of the sponge structure (sponge-like) was confirmed.

From the above, the ECTFE hollow fiber membrane of the present invention prepared by the non-solvent induced phase separation method is formed by adding silica as a pore-forming agent in the preparation of the mixed solution for the separation membrane to form micropores inside the hollow fiber membrane, it is remarkably when used as a water treatment separation membrane Improved water permeability was identified.

In addition, from the results of Examples 1 and 2, as the content of the pore-forming agent increases, the water permeability of the water treatment separation membrane is confirmed to be improved, and by adjusting the content of the pore-forming agent added, Physical properties can be controlled.

As described above, the present invention provides a ECTFE water treatment membrane prepared by a non-solvent induction phase separation method, consisting of a microporous layer of a sponge structure.

ECTFE water treatment membrane of the present invention can be produced by a non-solvent induction phase separation method, it is possible to produce a membrane at a lower temperature than the conventional thermal induction phase separation method, with the chemical resistance inherent in ECTFE, prepared by conventional non-solvent induction phase separation As the water permeability is significantly improved compared to the ECTFE hollow fiber membrane, when the ECTFE water treatment membrane is applied to the membrane module for water purification and wastewater treatment, it is possible to operate for a long time without any deterioration in performance.

In addition, the present invention provides an optimum method for producing an ECTFE hollow fiber membrane improved water permeability by introducing a specific pore-forming agent in the mixed solution in the membrane manufacturing process to induce fine pore formation in the membrane.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (11)

Polyethylene chlorotrifluoroethylene (ECTFE) water treatment separation membrane prepared by a non-solvent induced phase separation method, characterized in that the inside of the membrane consists of a sponge-like microporous layer. According to claim 1, The microporous layer of the sponge structure characterized in that the ECTFE water treatment membrane formed by a silica pore-forming agent. The ECTFE water treatment membrane of claim 1, wherein the water treatment membrane satisfies a water permeability of 70 l / m ² hr or more. The ECTFE water treatment membrane of claim 1, wherein the water treatment separation membrane is in the form of a flat membrane or a hollow fiber membrane. 1) prepare a mixed solution consisting of 10 to 50% by weight of the ECTFE polymer resin, 1 to 30% by weight of the pore-forming agent and 20 to 89% by weight of the solvent,
2) discharging the mixed solution from a nozzle, and flowing a lumen forming fluid into the nozzle to discharge the mixed solution to form a hollow fiber shape;
3) A method for manufacturing an ECTFE hollow fiber membrane comprising immersing and solidifying the solutions discharged from the nozzle in an external coagulation solution of a coagulation bath. The method of claim 5, wherein the mixed solution of step 1) is maintained at a temperature of 60 to 200 ℃. The method of manufacturing the ECTFE hollow fiber membrane according to claim 5, wherein the pore-forming agent of step 1) is hydrophilic or hydrophobic fumed silica. The method according to claim 5, wherein the solvent of step 1) is one or two or more selected from the group consisting of N-methylpyrrolidone, dimethylacetamide, triacetin, dibutyl phthalate and dioctyl phthalate. Method for producing the ECTFE hollow fiber membrane characterized in that. The lumen forming fluid of step 2) is one selected from the group consisting of diethylene glycol, N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, glycerol and water. Or a mixture of two or more kinds of ECTFE hollow fiber membranes. The method of manufacturing the ECTFE hollow fiber membrane according to claim 5, wherein the lumen forming fluid of step 2) is maintained at 10 to 200 ° C during discharge. The method of manufacturing the ECTFE hollow fiber membrane according to claim 5, wherein the distance from the nozzle to the surface of the external coagulation liquid of the coagulation bath is maintained at 10 to 100 mm in the step 3).

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