KR101494053B1 - Method for manufacturing asymmetric hollow fiber membrane and asymmetric hollow fiber membrane manufactured using the same - Google Patents

Abstract

The present invention relates to a method of forming a composite hollow fiber using a triple sheathing method, wherein the support layer is prepared by mixing polyvinylidene fluoride, poor solvent, and additives using a thermally induced phase separation (TIPS) And the coating layer was prepared by mixing polyvinylidene fluoride, a good solvent, a poor solvent, and an additive using a non-solvent induced phase separation (NIPS) A polymer solution is discharged at the same time to produce an asymmetric hollow fiber membrane through a spinning process, a phase transfer process, and a post-process, and an asymmetric hollow fiber membrane produced thereby.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an asymmetric hollow fiber membrane, and to an asymmetric hollow fiber membrane produced by the method. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a method for producing an asymmetric hollow fiber membrane and an asymmetric hollow fiber membrane produced thereby. More particularly, the present invention relates to a method for forming a hollow fiber membrane using a triple sheathing method, induced phase separation. The polymer solution was prepared by mixing polyvinylidene fluoride, poor solvent, and additives, and the coating layer was formed using polyvinylidene fluoride (NPS) using non-solvent induced phase separation (NIPS) , A method of preparing an asymmetric hollow fiber membrane through a spinning process, a phase transfer process, and a post-treatment process by simultaneously discharging two kinds of polymer solutions through a triple inserting process after preparing a polymer solution by mixing a good solvent, a poor solvent and an additive, And an asymmetric hollow fiber membrane produced thereby.

Recently, diverse membranes and membrane separation processes using these membranes have been actively developed in various application fields with the primary aim of energy saving and environmental protection. Particularly, since the separation membranes such as ultrafiltration membranes and microfiltration membranes have pores of several hundreds of nanometers to tens of micrometers in size, they are applied to various fields including waste water treatment, water production, food and medical industries, And the use thereof is gradually increasing.

For example, in the field of water treatment, high permeability capable of treating a large amount of water even with a small membrane area, and a high-pressure-resistant membrane excellent in mechanical properties without damaging the membrane under severe operating conditions are required. In addition, in order to fundamentally prevent the problem of film damage due to the introduction of various water treatment agents for removing the contaminants adhering to the surface of the membrane, the separation membrane material having excellent stain resistance and chemical resistance is also used Is required. In order to reflect these demands, the polyvinylidene fluoride polymer has been attracting much attention recently.

Since polyvinylidene fluoride polymer materials are well known to have low surface energy and excellent mechanical and chemical properties compared to conventionally known polysulfone or polyolefin-based membrane materials, it has long been known that microfiltration or ultrafiltration type separation materials And so on.

On the other hand, the thermally induced phase separation method (TIPS), which is a method of producing a separation filtration membrane using a polyvinylidene fluoride resin, involves liquid-solid phase separation and solidification by bringing a polymer solution dissolved at a high temperature into contact with a medium at a low temperature, (NIPS) is a method in which a polymer is dissolved in a solvent capable of dissolving a polymer, and a solvent and a non-solvent are exchanged in a polymer solution to induce liquid-solid phase separation and solidification, It is a method of achieving a separator. Although the non-solvent-based phase separation method can produce a more economical film, there is a problem in that the mechanical strength is not sufficient, and the thermally induced phase separation method can obtain a homogeneous high strength film, but macroboids are formed and defects such as pinholes are generated There is a possibility.

As a conventional example in which a polyvinylidene fluoride resin is used as a separation filtration membrane, Korean Patent Laid-Open No. 10-2010-0007245 discloses a method in which a separating active layer is introduced into the surface of a hollow fiber by using a triple- . However, this method has a higher rejection ratio than the conventional hollow fiber membrane using TIPS, but has a disadvantage in that it is difficult to control the pore size of the surface and has a disadvantage in that the pure water permeation amount is small.

Japanese Patent Application Laid-Open No. 2009-0034353 discloses a method of forming an asymmetric composite hollow fiber by coating a coating layer with a coating layer capable of controlling the pore size using NIPS after forming a high strength support separator using TIPS at the time of forming a hollow fiber. . However, this method is a post-coating method in which the coating method is performed after the support hollow fiber is formed, so that the thickness of the coating layer separation is not uniform and the performance of the hollow fiber is deteriorated and the coating layer is peeled off.

It is an object of the present invention to overcome the problems of the prior art as described above, and it is an object of the present invention to provide a hollow fiber membrane capable of forming a hollow fiber membrane having high strength, high water permeability and easy pore control using TIPS and NIPS, It is another object of the present invention to provide a method for producing an asymmetric hollow fiber membrane having a uniform thickness even after the hollow fiber membrane is formed by spinning the support layer and the coating layer solution simultaneously.

It is still another object of the present invention to provide an asymmetric hollow fiber membrane produced using the asymmetric hollow fiber membrane manufacturing method according to the present invention.

According to an aspect of the present invention, there is provided a method of manufacturing an asymmetric hollow fiber membrane using a triple sheath, the method comprising the steps of: discharging a hollow forming agent into an inner nozzle of a upper hollow, And discharging a polymer solution forming a support layer with a nozzle between the inside and the outside. The present invention also relates to a method of manufacturing an asymmetric hollow fiber membrane.

In the method of manufacturing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the support layer is phase-separated by a heat induction phase separation method (TIPS), and the coating layer is phase-separated by the non-solvent induced phase separation method .

In the method of manufacturing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the polymer solution forming the support layer includes polyvinylidene fluoride, a poor solvent, and an additive, and the polymer solution forming the coating layer is polyvinylidene Fluoride, a good solvent, a poor solvent and an additive.

In the method for producing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the polymer solution forming the support layer may contain 25 to 44% by weight of polyvinylidene fluoride, 55 to 70% by weight of gamma-butyrolactone as a poor solvent, And 10 to 20% by weight of polyvinylidene fluoride, 40 to 70% by weight of dimethylacetamide as a good solvent, and 2 to 10% by weight of a polyvinylpyrrolidone as an additive. 10 to 40% by weight of butyrolactone, 0.1 to 5% by weight of polyvinylpyrrolidone as an additive, and 0.1 to 5% by weight of acetylated methylcellulose.

In the method of manufacturing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the method is characterized in that the temperature of the polymer solution forming the support layer is in the range of 130 to 180 캜.

According to another aspect of the present invention, there is provided an asymmetric hollow fiber membrane produced by the method of the present invention as described above.

The asymmetric composite hollow fiber membrane according to one embodiment of the present invention is composed of an inner support layer and a hollow fiber of an outer coating layer, and the support layer is a spherical structure layer having a spherical solid component with an average diameter ranging from 0.1 to 10 μm .

In the asymmetric hollow fiber membrane according to an embodiment of the present invention, the coating layer is composed of a plurality of pores having a size ranging from 0.01 to 0.1 mu m and has a thickness ranging from 30 to 100 mu m.

The asymmetric hollow fiber membrane manufacturing method according to the present invention can form a hollow fiber membrane having high strength and high water permeability and easy pore control using TIPS and NIPS and can produce a hollow fiber by simultaneously spinning the support layer and the coating layer solution through the triple- It is possible to produce an asymmetric hollow fiber membrane having a uniform thickness even after film formation and in which the coating layer is not peeled off.

In particular, the asymmetric hollow fiber membrane produced by the production method of the present invention is effective in introducing hydrophilicity of a polyvinylidene fluoride (PVDF) hollow fiber membrane, which is a hydrophobic hollow fiber membrane, by adding acetylated methyl cellulose of the cellulose acetate system as an additive .

1 is an electron micrograph of an asymmetric hollow fiber membrane produced by the method of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to examples and the like. In the following description of the present invention, a detailed description of known general functions or configurations will be omitted.

The present invention relates to a method of producing an asymmetric hollow fiber membrane using a triple sheathing method, wherein the method comprises discharging a hollowing agent with an inner nozzle of a upper sheath, discharging a polymer solution forming a coating layer with an outer nozzle, And a method of manufacturing an asymmetric hollow fiber membrane.

Hereinafter, the production process of the hollow fiber membrane of the present invention will be described in more detail.

A process for producing a polymer solution forming a support layer ;

In the method for producing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the polymer solution forming the support layer includes polyvinylidene fluoride, a poor solvent, and an additive. In this case, the content ratio of each component is preferably 25 to 45% by weight of polyvinylidene fluoride, 55 to 70% by weight of a poor solvent, and 1 to 10% by weight of an additive.

In the present invention, the polyvinylidene fluoride polymer forming the hollow fiber membrane may have a weight average molecular weight of 100,000 to 700,000,000 daltons, or may be composed of a mixture of two or more species. Examples of the poor solvent in the production process of the present invention include gamma-butyrolactone, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, cyclohexanone, And the like, and it is preferable to use gamma-butyrolactone.

Specific examples of the additive include polyvinyl pyrrolidone having a weight average molecular weight of 15,000 daltons to 90,000 daltons, polyethylene glycol having a weight average molecular weight of 200 to 20,000 daltons, polyvinyl alcohol, and anhydrous Maleic acid, and a surfactant. The hydrophilic polymer may be used alone or in admixture of two or more. The hydrophilic polymer may be added to the polyvinylidene fluoride polymer solution, preferably polyvinyl pyrrolidone.

In the present invention, the polymer solution for forming the support layer is preferably prepared at 120 to 200 ° C and must be subjected to a defoaming process in order to remove bubbles present in the solution. Generally, a hollow fiber membrane is formed by solidification at a temperature of 120 ° C or less, or a phase separation at the time of contact with a non-solvent of 120 ° C or lower. Therefore, in order to produce the polyvinylidene fluoride hollow fiber membrane, it is preferable to discharge the polymer solution as a coagulating solution through a spinning nozzle maintaining a temperature of at least 120 ° C, preferably 130 to 180 ° C.

A process for preparing a polymer solution for forming a coating layer ;

In the method of manufacturing an asymmetric hollow fiber membrane according to an embodiment of the present invention, the polymer solution forming the coating layer includes polyvinylidene fluoride, a good solvent, a poor solvent, and an additive. In this case, the content ratio of each component is preferably 10 to 20% by weight of polyvinylidene fluoride, 40 to 70% by weight of a good solvent, 10 to 40% by weight of a poor solvent, and 0.1 to 10% by weight of an additive.

In the production method of the present invention, examples of suitable solvents include N, N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylacetamide, dimethylformamide, ), And the like can be used, but it is preferable to use dimethylacetamide. The poor solvent is as described above.

The polymer solution forming the coating layer preferably contains 0.1 to 5% by weight of polyvinylpyrrolidone and 0.1 to 5% by weight of acetylated methylcellulose as an additive. As an additive, polyvinylpyrrolidone is used for forming pores in the hollow fiber membrane. Particularly, by adding acetylated methyl cellulose of the cellulose acetate system as an additive, the hydrophilic hollow fiber membrane of polyvinylidene fluoride (PVDF) Is preferably introduced.

Hollow formers  Manufacture process;

The hollow formers are prepared by dissolving dimethylpyrrolidone, dimethyl acetate, dimethylformamide, dimethylsulfoxide and the like as a non-solvent in water or ethylene glycol as a non-solvent, and using a ratio of good solvent to non-solvent at room temperature 2 to 8 to 8 to 2 at normal temperature and defoamed, and the temperature is maintained at 1 to 80 ° C when it is transferred to the triple spinning nozzle.

Preparation of hollow fiber membranes;

In the present invention, the polymer solution forming the support layer, the polymer solution forming the coating layer, and the hollowing agent are simultaneously discharged into the coagulating solution by using the triple sheathing to have a support layer of a spherical structure and a coating layer containing a plurality of pores A hollow fiber membrane is prepared. At this time, the polymer solution for discharging the hollow polymer is discharged from the inner nozzle of the upper nozzle, the polymer solution for forming the coating layer is discharged from the outer nozzle, and the polymer solution for forming the supporting layer is discharged by the nozzle between the inside and the outside.

The coagulating solution used in the present invention is composed of a non-solvent containing a non-solvent such as pure water or a certain amount of a good solvent, and an inner surface having macropores is formed therein .

As described above, the asymmetric hollow fiber membrane according to the present invention can form a hollow fiber membrane which is easy to control pores with high strength and high water permeability by using TIPS for the support layer and phase separation using NIPS. In particular, it is possible to produce an asymmetric hollow fiber membrane having a uniform thickness even after the hollow fiber membrane is formed by spinning the support layer and the coating layer solution simultaneously through the triple inserting process, and the coating layer is not peeled off.

Washing process;

In addition, the present invention may further include a washing process to remove organic matter including solvent remaining in the membrane of the hollow fiber membrane transferred from the coagulating solution to the atmosphere. The use of water as a washing solution is preferred, and the washing time is not particularly limited, but is preferably at least 1 day and at most 5 days.

Another aspect of the present invention relates to an asymmetric hollow fiber membrane produced by the method of the present invention as described above, wherein FIG. 1 is an electron micrograph of an asymmetric hollow fiber membrane produced by the method of the present invention.

The asymmetric hollow fiber membrane according to one embodiment of the present invention is composed of an inner support layer and a hollow fiber of an outer coating layer, and the support layer is formed of a spherical structure layer having a spherical solid component with an average diameter ranging from 0.1 to 5 μm. The coating layer is formed of a plurality of pores having a size ranging from 0.01 to 0.1 mu m, and preferably has a thickness ranging from 30 to 100 mu m.

The asymmetric hollow fiber membrane according to the present invention maintains high strength while having high water permeability and high rejection ratio, and it can be used as a separation membrane module for water treatment, a separation membrane module for heavy water treatment, an immersion membrane module for biofilm reactor, A pretreatment membrane module for desalination, and the like, and exhibits high economic efficiency and processing performance, and does not cause deformation or deterioration even in long-term use. Therefore, it can be applied to a next-generation high-efficiency separation process.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example

In order to produce a polyvinylidene asymmetric hollow fiber membrane, a support layer is prepared by a heat-induced phase separation method, and a coating layer is prepared using a non-solvent separation method,

      The supporting layer was prepared by charging 55% by weight of gamma-butyrolactone, which is a poor solvent, into a dissolution tank, heating the mixture to 50 DEG C, adding 3% by weight of polyvinylpyrrolidone having a weight average molecular weight of 19,000 daltons as an organic additive, After the temperature was elevated, a polyvinylidene fluoride polymer having a weight average molecular weight of 440,000 daltons of 42 wt% was slowly added thereto, and the temperature was raised to 150 ° C. to prepare a uniform spinning solution.

The coating layer was prepared by charging 35% by weight of dimethylacetamide and 40% by weight of gamma-butyrolactone, which are poor solvents, into a dissolution tank, stirring the mixture, adding 9% by weight of polyvinylpyrrolidone and 1% by weight of acetylated methylcellulose %, And the mixture was heated to 60 DEG C, and 15 wt% polyvinylidene fluoride polymer was gradually added to prepare a spinning solution

Subsequently, the spinning solution for forming the support layer was flowed into a middle nozzle of a triple cage at 150 ° C, and a hollow forming agent mixed with dimethyl acetate and ethylene glycol in an amount of 6 to 4 was flowed to form a hollow. The spinning solution for forming the coating layer was flowed to 5 캜. All three solutions were spun into a coagulation bath consisting of water at 5 degrees Celsius and finally solidified.

The hollow fiber membrane produced had an inner diameter of 0.7 millimeters and an outer diameter of 1.3 millimeters. The tensile strength was 1000 grams per unit hollow fiber membrane and the elongation was 60 percent. The membrane permeation pressure at 50 kPa and the permeability flux at 25 캜 were 800 liters per unit time unit area. The 100 percent inhibition of polystyrene particles was 99 percent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. This will be obvious.

Claims (9)

1. A method for producing an asymmetric hollow fiber membrane using a triple-
The method comprises discharging a hollow forming agent through an inner nozzle of a triple nozzle, discharging a polymer solution forming a coating layer with an outer nozzle, discharging a polymer solution forming a supporting layer with a nozzle between the inside and the outside,
Wherein the support layer is phase-separated by a heat-induced phase separation method (TIPS), and the coating layer is phase-separated by a non-solvent-derived phase separation method (NIPS). delete The method of claim 1, wherein the polymer solution forming the support layer comprises polyvinylidene fluoride, a poor solvent, and an additive, and the polymer solution forming the coating layer comprises polyvinylidene fluoride, a good solvent, a poor solvent and an additive Wherein the asymmetric hollow fiber membrane has a thickness of about 5 mm. delete 4. The method according to claim 3, wherein the polymer solution forming the support layer comprises gamma-butyrolactone as a poor solvent and polyvinylpyrrolidone as an additive, and the polymer solution forming the coating layer comprises dimethylacetamide as a good solvent, Wherein the additive comprises polyvinylpyrrolidone and acetylated methylcellulose, wherein the additive is selected from the group consisting of gamma-butyrolactone, polyvinylpyrrolidone, and acetylated methylcellulose. 4. The method as claimed in claim 3, wherein the temperature of the polymer solution forming the support layer is in the range of 130 to 180 占 폚. An asymmetric hollow fiber membrane produced by the method of any one of claims 1, 3 and 5 to 6. The asymmetric hollow fiber membrane according to claim 7, wherein the asymmetric hollow fiber membrane is made of a hollow fiber having an inner support layer and an outer coating layer, and the support layer is a spherical structure layer made of a spherical solid component having an average diameter ranging from 0.1 to 10 [ Hollow fiber membrane. The asymmetric hollow fiber membrane according to claim 7, wherein the coating layer is composed of a plurality of pores having a size ranging from 0.01 to 0.1 mu m and has a thickness ranging from 30 to 100 mu m.

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