KR101648843B1 - A preparation method of fouling-resistant hollow fiber membrane and a fouling-resistant hollow fiber membrane prepared by the same - Google Patents

Abstract

More particularly, the present invention relates to a method for producing a stain resistant hollow fiber membrane and a stain resistant hollow fiber membrane produced by the above method, and more particularly to a stain resistant hollow fiber membrane produced by spraying a polymeric spinning solution with vortexing in a spinning nozzle, A method of manufacturing a hollow fiber membrane in which a plurality of projections are continuously or discontinuously formed in a direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane to improve the stain resistance and maintain the properties of the hollow fiber membrane such as the average pore size and the pure water permeation amount, Resistant hollow fiber membrane produced by the method of the present invention.

Description

Technical Field [0001] The present invention relates to a method for producing a stain resistant hollow fiber membrane and a stain resistant hollow fiber membrane prepared by the above method,

More particularly, the present invention relates to a method for producing a stain resistant hollow fiber membrane and a stain resistant hollow fiber membrane produced by the above method, and more particularly to a stain resistant hollow fiber membrane produced by spraying a polymeric spinning solution with vortexing in a spinning nozzle, A method of manufacturing a hollow fiber membrane in which a plurality of projections are continuously or discontinuously formed in a direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane to improve the stain resistance and maintain the properties of the hollow fiber membrane such as the average pore size and the pure water permeation amount, Resistant hollow fiber membrane produced by the method of the present invention.

In recent years, interest in separation membranes has increased in the water treatment process, and water stability, compact site, and automation advantages are high. In particular, the use of ultrafiltration membranes is increasing. In addition to water treatment, water reuse is also increasing in preparation for water shortages. Most of the membranes used in water treatment are required to be used for a long period of time and it is necessary to slow down the rate of contamination of the membranes. Pollution of the membranes is accelerated in the case of hydrophobic polymer membranes, and membranes using hydrophilic polymers are relatively stable against membrane contamination. In the case of a hydrophilic polymer, there is a disadvantage in that the membrane has a relatively high resistance to contamination, but the physical properties thereof are poor.

Accordingly, there is a growing demand in the industry for a method of economically manufacturing a separation membrane having excellent mechanical strength, capable of completely removing pathogenic microorganisms, and having high permeation flow rate and high membrane fouling resistance.

As a literature related to a method of producing a membrane having high resistance to film fouling, Korean Patent Registration No. 10-1179161 discloses a method for producing a hollow fiber membrane by coating a hollow fiber membrane with polyvinylidene fluoride (PVDF) It has been disclosed that a hollow fiber membrane in which film contamination of a hydrophobic substance is reduced can be produced by mixing a hydrophilic agent having excellent compatibility and compatibility with PVDF with the polymer resin and spinning it. However, if a manufacturing method capable of further improving the degree of contamination resistance that can be achieved by such a method is developed, it is expected to be more industrially applicable.

Under such circumstances, the inventors of the present invention have found that by spinning a polymer spinning solution while causing a vortex in a spinning nozzle, a large number of projections are continuously or discontinuously formed in the direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane, The average pore size and the pure permeation amount of the hollow fiber membrane can be fabricated, and the present invention has been completed.

An object of the present invention is to provide a method for producing a hollow fiber membrane in which physical properties of the hollow fiber membrane such as average pore size and pure permeation amount are maintained while the stain resistance is improved.

Another object of the present invention is to provide an antifouling hollow fiber membrane produced by the above production method.

In order to solve the above problems, the present invention provides a method for producing a contamination-resistant hollow fiber membrane, comprising the steps of:

1), an inner hole forming agent and a polymer spinning solution are fed to a multi-tubular nozzle having a first nozzle, a second nozzle, ..., and an n-th nozzle (n≥2) (Step 1);

2) In the first nozzle, the inner hole forming agent is radiated, and in the remaining nozzles except for the first nozzle, the polymer solution is emitted which has the same or different composition. At this time, in the nth nozzle as the outermost nozzle, (Step 2); And

3) a step of phase-transforming the radiated polymer spinning solution to produce a hollow fiber membrane (step 3).

Preferably, the polymer spinning solution of step 1) above can be prepared through the following steps:

a) dissolving the polymer in a positive solvent, a poor solvent or a mixed solvent thereof to prepare a polymer solution (step a); And

b) heating the polymer solution to prepare a polymer spinning solution (step b).

Hereinafter, the configuration of the present invention will be described in detail.

The present invention is characterized in that a polymeric spinning solution is radiated while causing a vortex in a spinning nozzle so that a plurality of projections, preferably uniform, are continuously or discontinuously formed in the direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane, And the hollow fiber membranes maintained the physical properties of the hollow fiber membranes such as the average pore size and the pure permeation amount. That is, in the present invention, it is possible to improve the stain resistance of the hollow fiber membrane by making the surface of the hollow fiber membrane smooth on the smooth surface, preferably regularly, by the eddy current generated during spinning, There is no deterioration.

The step (a) is a step of preparing a polymer solution by dissolving the polymer in a good solvent, a poor solvent or a mixed solvent thereof, wherein the polymer is dissolved in a solvent, a poor solvent or a mixed solvent thereof to prepare a polymer solution .

In the present invention, the polymer may be a fluorine-containing polymer, a cellulose-based polymer, a sulfone-based polymer, a sulfide-based polymer, a polyolefin-based polymer, or a mixture thereof, but is not limited thereto. Specifically, the polymer may be at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, acetylmethanol, polysulfone, polyisocyanate, polyphenylene sulfide , Polypropylene, polyethylene, or a mixture thereof. In the present invention, it is particularly preferable to use polyvinylidene fluoride (PVDF) as a polymer in the case of producing the water-resistant hollow fiber membrane for water treatment from the viewpoint of chemical resistance.

In the present invention, the polymer may be used in an amount of 10 to 50% by weight, preferably 10 to 50% by weight, in the whole polymer solution. If the amount is less than 10% by weight, the strength of the hollow fiber membrane is too weak. There is a problem that it is difficult to form through the spinning. In the present invention, when polyvinylidene fluoride is used as the polymer, PVDF is preferably used in an amount of 12 to 30% by weight in the whole polymer solution. If the amount of PVDF is less than 12% by weight, protrusions are not formed on the surface of the hollow fiber and the strength is weakened. When the amount of PVDF is more than 30% by weight, the viscosity of the polymer resin is high, It is preferable to emit within the above range.

The term "good-solvent " as used in the present invention means a solvent capable of dissolving the polymer at about 60 캜 or lower. In the present invention, the two polymers may be appropriately selected and used depending on the type of polymer, which is generally known to be usable in the art. Specifically, the two solvents usable in the present invention may be any one or more selected from the group consisting of dimethylacetamide, dimethylformamide, polar solvents such as dimethylsulfoxide, ketones such as acetone, methyl ethyl ketone, and cyclic ketones such as? -Butyrolactone But is not limited thereto. In the present invention, when polyvinylidene fluoride is used as the polymer, dimethylacetamide can be used as a good solvent.

In the present invention, both of the polymers may be used in an amount of 40 to 90% by weight, preferably in the range of 40 to 90% by weight. If the amount of the polymer is less than 40% by weight, the viscosity of the polymer solution is too high, The strength of the hollow fiber membrane is too weak.

The term "poor-solvent " used in the present invention means a solvent capable of dissolving a polymer at a temperature of 60 DEG C or higher or below a melting point of a polymer at a low temperature below 60 DEG C do. Although the poor solvent is inert to a relatively high polymer material, it can maximize the pore size and porosity of the surface of the hollow fiber membrane. When added to the polymer solution, it influences temperature change, viscosity change and ease of molding process. In addition, it plays a major role in suppressing the formation of macrovoids to obtain high strength and high water permeability. These poor solvents are conventionally used in the art and specifically include ethylene glycol such as diethylene glycol, diethylene glycol monohexyl ether (n-hexylcarbitol), phthalates such as dimethyl phthalate, cyclohexanone, isophorone, gamma A single compound or two kinds of monomers selected from among butyrolactone, methyl isoamyl ketone, dimethyl phthalate, propyleneglycol methyl ether, propylenecarbonate, diacetone alcohol, glycerol triacetate, glycol ester and organic carbonate The above-mentioned mixture may be used, and diethylene glycol is preferably used.

In the present invention, the poor solvent may be used in an amount of 5 to 30% by weight, preferably 5 to 30% by weight, in the whole polymer solution. If the amount is less than 5% by weight, Is too large and the strength of the hollow fiber membrane is weak.

In the present invention, the polymer solution of step a) may further comprise a pore-forming agent.

The term "pore-forming agent" used in the present invention means a substance added to promote pore formation of the hollow fiber membrane. The pore-forming agent increases the pore size and increases the permeation flow rate. Specifically, the pore-forming agents usable in the present invention include lithium chloride, zinc chloride, magnesium sulfate, magnesium chloride, silica, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), camphorsulfonic acid (CSA), and toluenesulfonic acid TSA), but the present invention is not limited thereto. In the present invention, when polyvinylidene fluoride is used as the polymer, polyethylene glycol (PEG) can be used as the pore-forming agent.

In the present invention, the pore-forming agent may be used in an amount of 1 to 5% by weight, preferably in the range of 1 to 5% by weight in the whole polymer solution. If the amount is less than 1% by weight, the pore size may not be increased, If it exceeds 5% by weight, the strength may become weak.

The step (b) is a step of preparing a polymer spinning solution by heating the polymer solution, and heating the polymer solution to facilitate spinning to prepare a polymer spinning solution.

In the present invention, in order to produce the polymer spinning solution, the polymer solution is heated at 50 to 200 DEG C for 3 to 10 hours, and then transferred to a spinning nozzle. If the polymer solution is heated to less than 50 ° C, solidification of the polymer solution occurs and the polymer can not be spinned. When heated to a temperature exceeding 200 ° C, polymer degradation occurs, resulting in weak strength or carbonization of the polymer. Lt; / RTI >

In the present invention, the polymer spinning solution is allowed to stand for a certain period of time to be stabilized, and then the bubbles remaining in the stabilized polymer solution are removed and filtered, and then heated to 50 to 200 ° C to prepare a spinning solution . When the heating is carried out at a temperature lower than 50 ° C, complete dissolution does not occur, resulting in poor processability. When the temperature exceeds 200 ° C, the polymer may be decomposed. The stabilization may be performed at 100 to 150 ° C for 1 to 24 hours.

In the step 1, a plurality of tubular nozzles each having a first nozzle, a second nozzle,..., And an nth nozzle (n? 2) are disposed in order from the inside to the outside, And a step of transferring the polymer spinning solution.

In the present invention, the polymer spinning solution can be stored in a spinning solution storage tank of a predetermined size until it is radiated. At this time, the reservoir is preheated and set at a temperature of 110 to 160 ° C, preferably about 5 to 10 ° C higher than the appropriate temperature of the polymer solution to be introduced. This is to prevent the heat loss in the reservoir. The inside of the reservoir should be completely removed of moisture and sealed, and the heat loss should be prevented by wrapping it with a heating band to maintain the temperature. The reservoir is connected to the polymer spinning liquid transfer line and the nozzle for discharging the hollow fiber membrane, and is also connected to a metering pump or nitrogen gas for pushing the polymer spinning solution. When the polymer spinning solution in the reservoir is stabilized, it is pushed by a metering pump of a constant flow rate or a valve of nitrogen gas is opened to apply a certain pressure. Normally, the discharge speed is determined by the nitrogen pressure used for maintaining the pressure, It has a significant impact on performance. At this time, it is preferable that the nitrogen pressure is maintained in the range of 0.1 to 1.5 kgf / cm 2, preferably 0.1 to 1 kgf / cm 2. This pressure is proportional to the rate at which the polymer spinning solution passes through the nozzle to the phase transfer bath, and the speed is preferably maintained at about 10 to 20 cm / sec.

In the present invention, when the nitrogen pressure is too high and the pressure exceeds 20 cm / sec, the discharge rate may be increased to increase the amount to be obtained. However, since the phase transition occurs very rapidly, the porosity and pore size can not be properly obtained. Strength can be increased. On the other hand, if the nitrogen pressure is too weak and the discharge rate is less than 10 cm / sec, the separation membrane acquisition time becomes longer, but the porosity and the pore size can be appropriately obtained. However, since the strength of the film relatively decreases, it is desirable to maintain the above range.

In the present invention, it is preferable to heat the transfer line and the nozzle to keep the temperature constant from the spinning liquid tank to the nozzle when transferring the polymer spinning solution.

In the present invention, an inner hole forming agent is separately transferred to the same nozzle together with the polymer spinning solution transferred by the nitrogen pressure. In the present invention, the distal end portion of the nozzle where the polymer spinning solution and the inner hole forming agent meet forms a circular shape peculiar to the hollow fiber membrane, which determines the outer diameter and inner diameter of the hollow fiber membrane.

Specifically, when the polymer spinning solution is transferred to the second nozzle, ..., and the nth nozzle of the multi-tubular nozzle forming the hollow fiber membrane shape through the transfer line, the first nozzle of the multi-tubular nozzle makes the inner hole of the hollow fiber membrane The inner hole forming agent is metered and pumped at a constant rate so that the inner hole forming agent is uniformly transported to the nozzle.

The term "inner hole-forming agent" used in the present invention means a material to be injected to form an intermediate hole when the polymer spinning solution is radiated.

In the present invention, the inner hole-forming agent may be a poor solvent, a non-solvent or a mixed solvent thereof, and may be further mixed with a suitable solvent. The type of the internal hole forming agent may be appropriately selected depending on the kind of the polymer.

The term "non-solvent" used in the present invention means a solvent which does not dissolve or swell the polymer until the melting point of the polymer or the boiling point of the liquid. Specifically, the non-solvent usable in the present invention may be water, alcohol, ether, hexane and the like, but is not limited thereto.

In the present invention, when the polymer is PVDF, the non-solvent and the positive solvent may be mixed in a weight ratio of 1: 0.1 to 1.5, more preferably 0.1: 1. If the non-solvent and the two solvents are less than 1: 0.1 weight ratio, it is difficult to form the pores of the inner hole of the hollow fiber membrane. If the ratio is more than 1: 1.5 weight ratio, dissolution of the inner holes may occur. When the polymer is a cellulosic polymer, the inner hole-forming agent may be a poor solvent, and may be added with a non-solvent. Examples of the poor solvent used as the inner hole forming agent include triethylene glycol, diethylene glycol, glycerin, 2-methyl-2,4-pentanediol, 2-ethyl-1,3- Or a mixed solvent of two or more selected from the above. The non-solvent may be one or more selected from water, ethylene glycol, alcohols and ketones, and water may be preferably used. When the non-solvent is added, the poor solvent and the non-solvent are contained in the weight ratio of 1: 0.1 to 1: 0.5, more preferably 1: 0.2 to 1: 0.4, have.

In the present invention, the temperature of the inner hole-forming agent is 1 to 60 ° C, preferably 10 to 50 ° C, and if the temperature is less than 1 ° C, icing occurs to form an inner hole. When the temperature is higher than 60 ° C, There may be a problem where it is difficult to get up and consecutively spinning.

In the step (2), the inner hole forming agent is radiated from the first nozzle to form the contamination-resistant hollow fiber membrane having protrusions on the surface, and in the remaining nozzles except for the first nozzle, At this time, in the n-th nozzle, which is the outermost nozzle, the polymer spinning solution is radiated while generating a vortex.

According to the present invention, it is possible to produce an anti-staining hollow fiber membrane having projections on the surface, preferably regular and uniform, by spinning the polymer spinning solution while causing eddy current in the n-th nozzle as the outermost nozzle of the multiple tubular nozzle .

In the present invention, the vortex of the polymer spinning liquid in the n-th nozzle in the step 2) has a donut-shaped plate having an inner circumferential surface and an outer circumferential surface and a projection on the inner circumferential surface, Other rotations can take place and other ways that can cause eddy currents in the outer nozzle can be used.

In one specific embodiment, a donut-shaped plate having an inner circumferential surface and an outer circumferential surface and a projection on the inner circumferential surface is mounted on the lower end of a double-tube nozzle, as schematically shown in FIGS. 1 and 2, the inner hole forming agent is emitted from the first nozzle 1 and the polymer spinning liquid is emitted from the second nozzle 2. At this time, the donut-shaped plate ( 3) is rotated and radiation is performed. 1 and 2, protrusions provided on the inner circumferential surface of the donut-shaped plate 3 partially come in contact with the second nozzle 2, which is the radiation path of the polymer spinning solution of the double-tubular nozzle, Vortex may occur when the polymer spinning solution is radiated as the donut-shaped plate 3 is rotated.

In another specific embodiment, a donut-shaped plate having an inner circumferential surface and an outer circumferential surface and a projection on the inner circumferential surface is mounted on the lower end of a triple-tubular nozzle as shown schematically in FIGS. 3 and 4, the inner hole forming agent is emitted from the first nozzle 1 'and the two kinds of polymer spinning solution are radiated from the second nozzle 2' and the third nozzle 4, respectively, The donut-shaped plate 3 'mounted on the lower end of the tubular nozzle is rotated, and radiation is performed. 3 and 4, the protrusion provided on the inner circumferential surface of the donut-shaped plate 3 'has a third nozzle 4 as a radiation path of the polymer spinning solution located at the outermost of the triple-tubular nozzle, A vortex may occur when the polymer spinning solution is radiated while the donut-shaped plate 3 'is rotated.

In the present invention, the number of projections of the plate is preferably 3 to 450, more preferably 100 to 400, and still more preferably 200 to 400. If the number of protrusions of the plate is less than 3, it is difficult to form protrusions on the surface of the hollow fiber membrane. If the number of the protrusions exceeds 450, the protrusions are connected to the surface of the hollow fiber membrane,

In the present invention, the height of the projection of the plate may be 0.01 to 100 탆. If the height of the projections of the plate is less than 0.01 탆, there is a disadvantage that the stain resistance is not greatly affected. If the height exceeds 100 탆, the surface of the separation membrane is irregular and the hollow fiber is difficult to spin.

In the present invention, the interval between the projections of the plate may be 0.01 to 200 탆. If the distance between the projections of the plate is less than 0.01 mu m, there is a disadvantage in that the effect on staining resistance is small. On the other hand, if the spacing is more than 200 mu m, stain resistance is deteriorated.

In the present invention, a hollow fiber membrane having various physical properties and functionalities can be produced by variously changing the composition of the polymer spinning solution. Further, by using a plurality of kinds of the polymer spinning solution having different compositions from each other, it is possible to produce a hollow fiber membrane having more various properties and functionality. Specifically, when using the triple-tubular nozzle shown in Figs. 3 and 4, the polymer spinning solution for coating layer is transferred to the second nozzle 2 'and the polymer spinning solution for supporting layer is transferred to the third nozzle 4, And the support layer are integrated with each other. At this time, the polymer spinning solution for the coating layer may contain 8% by weight of acetylated methyl cellulose, 4% by weight of cellulose acetate, 78% by weight of dimethylacetamide as a solvent, and 10% by weight of triethylene glycol as a diluent, The polymer spinning solution may contain 25% by weight of acetylated methyl cellulose, 45% by weight of triethylene glycol as a diluent, 20% by weight of dimethylacetamide as a solvent, and 10% by weight of glycerin.

In the step 3, the spinning polymer solution is phase-transformed to produce a hollow fiber membrane.

In the present invention, the phase transition tank for the phase transition may be a mixture of one or more selected from the group consisting of water, ethylene glycol such as triethylene glycol, diethylene glycol, and ethylene glycol. In the present invention, when polyvinylidene fluoride is used as the polymer, pure water can be used as the phase transfer bath.

The hollow fiber formed through the above process is immersed in the nonwoven for final coagulation. The non-solvent is the same as defined above, and a mixed solution of a poor solvent and a poor solvent may be used for the non-solvent. The poor solvent and the two solvents are as defined above, and one or more of the poor solvent and the two solvents are used.

In the present invention, the temperature of the phase transfer bath in which the reaction takes place is -10 to 90 ° C, preferably 10 to 50 ° C. If the temperature is lower than -10 ° C, It takes a long time for the spinning solution to solidify and it is difficult to obtain a hollow fiber membrane having a desired standard and pore size.

The hollow fiber membrane thus obtained is preferably dried at a temperature of 70 to 100 ° C, more preferably 3 to 6 hours in a water bath elevated to a boiling point of water or below, more preferably at a temperature of not lower than the boiling point of water, Hydrothermal treatment is carried out until a state of no smell occurs. The hydrothermal treatment is advantageous in that the water permeability and strength are increased.

The present invention also provides a contamination-resistant hollow fiber membrane produced by the method of the present invention, in which a plurality of projections are continuously or discontinuously formed in a direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane.

The hollow fiber membrane produced according to the method of the present invention can prevent the attachment of contaminants due to a multiplicity of protrusions formed on the surface, thereby improving the stain resistance and at the same time, maintaining the physical properties of the hollow fiber membrane such as average pore size and pure water permeation .

In the present invention, the plurality of projections may be uniformly formed on the surface, but are not limited thereto. In the present invention, when the plurality of protrusions are uniformly formed, the adhesion of the contaminants can be prevented more effectively, and the stain resistance can be further improved.

Specifically, in an embodiment of the present invention, a PVDF polymer solution is prepared and then heated to prepare a polymer spinning liquid. The inner hole forming agent is transported to the inner nozzle of the double pipe type nozzle, that is, the first nozzle And a donut-shaped plate having 100, 200, 400 or 450 protrusions formed on the inner circumferential surface of the polymer spinning solution was transported to the outer nozzle of the double pipe type nozzle mounted on the lower end, that is, the second nozzle, PVDF hollow fiber membranes with protrusions formed on their surfaces were prepared and their physical properties such as average pore size and pure water permeability were radiated with the plate removed to compare them with PVDF hollow fiber membranes having no protrusions. As a result of measuring the stain resistance of these hollow fiber membranes, it was found that the hollow fiber membrane having the projections on the surface of the present invention had no protrusions It was confirmed that the stain resistance was much better than that of the construction film.

In the present invention, the height of the protrusions formed on the surface of the hollow fiber membrane may preferably be in the range of 0.01 to 100 mu m, more preferably 0.01 to 10 mu m, and still more preferably 0.01 to 1 mu m. Further, in the present invention, the distance between the projections formed on the surface of the hollow fiber membrane may preferably be in the range of 0.1 to 100 占 퐉, more preferably 0.01 to 10 占 퐉, and still more preferably 0.01 to 1 占 퐉. Particularly, in the present invention, if the height of the protrusions formed on the surface of the hollow fiber membrane is 0.01 to 100 탆 and the interval between the protrusions is 0.1 to 100 탆, the adhesion of the contaminants can be prevented more effectively and the stain resistance can be further improved .

In the present invention, the hollow fiber membrane can be widely used for water treatment such as wastewater, water treatment, etc., but is not limited thereto, and can be used for various purposes known in the art depending on the type of polymer and physical properties. In particular, the hollow fiber membrane produced according to the method of the present invention is excellent in resistance to membrane fouling and is suitable for use as a water treatment hollow fiber membrane due to a long backwash cycle due to membrane contamination. The hollow fiber membrane of the present invention can be used, for example, in a water purifier, a pretreatment device of a seawater desalination process, a water softener, a water treatment device, a wastewater treatment device or a food purification device.

In addition, the present invention provides a method for producing water-treated water comprising the step of water-treating the water-resistant hollow fiber membrane.

In the present invention, the water used for the water treatment may be seawater, wastewater or the like.

In the present invention, the water treated may be drinking water, purified water, or the like.

In the present invention, the water treatment may be microfiltration, ultrafiltration, nanofiltration, reverse osmosis, or a combination thereof.

The present invention also provides a multi-tubular nozzle having a first nozzle, a second nozzle, ..., and an nth nozzle (n? 2) in order from the inside to the outside; And a donut-shaped plate mounted on a lower end of the multiple tubular nozzle, the plate having an inner circumferential surface and an outer circumferential surface and a projection on the inner circumferential surface.

In the present invention, the nozzle for manufacturing the contamination-resistant hollow fiber membrane may be used in place of the nozzle portion of the existing spinning apparatus for manufacturing a hollow fiber membrane.

The present invention is characterized in that a polymeric spinning solution is radiated while causing a vortex in a spinning nozzle so that a plurality of projections, preferably uniform, are continuously or discontinuously formed in the direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane, The hollow fiber membranes maintained the physical properties of the hollow fiber membranes such as the average pore size and the pure permeation amount can be produced. In the present invention, the hollow fiber membrane is excellent in resistance to membrane contamination and is suitable for use as a hollow fiber membrane for water treatment such as wastewater and water treatment because of a long backwash cycle due to membrane contamination.

FIG. 1 is a perspective view schematically showing a double pipe type nozzle having an inner circumferential surface and an outer circumferential surface and a plate of a donut shape provided with projections on the inner circumferential surface thereof, mounted on the lower end.
FIG. 2 is a cross-sectional view schematically showing a double pipe type nozzle having an inner circumferential surface and an outer circumferential surface and a donut-shaped plate having protrusions on the inner circumferential surface thereof mounted on the lower end.
FIG. 3 is a perspective view schematically showing a triple-tubular nozzle having an inner circumferential surface and an outer circumferential surface and a plate-shaped donut having a projection on the inner circumferential surface thereof mounted on the lower end thereof.
FIG. 4 is a cross-sectional view schematically showing a triple-tubular nozzle having an inner circumferential surface and an outer circumferential surface and a donut-shaped plate having protrusions on the inner circumferential surface thereof mounted on the lower end thereof as another embodiment.
5 shows the results of analysis of the surface morphology of the PVDF hollow fiber membrane of the present invention prepared in Example 1 by scanning electron microscopy (SEM).

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Example 1: Preparation of PVDF hollow fiber membrane having protrusions on its surface

A polymer solution was prepared by mixing 25 wt% of PVDF, 60 wt% of dimethylacetamide (DMAc) and 15 wt% of polyethylene glycol (PEG 600, molecular weight 600), and then heated at 150 캜 with stirring to prepare a polymer spinning solution Respectively. As the inner hole forming agent, a solution obtained by mixing DMAc and water at a weight ratio of 1: 1 was transferred to the inner nozzle of the double pipe type nozzle, that is, the first nozzle 1 shown in FIG. 1, at a temperature of 10 ° C by using a metering pump Then, the polymer spinning solution was transferred to an outer nozzle, that is, a second nozzle 2 mounted on the lower end, with a donut-shaped plate 3 having 100 protrusions formed on its inner circumferential surface at a temperature of 150 ° C. Then, the PVDF hollow fiber membrane was spinned at a distance of 5 cm from the solidification joining water and wound at the rear end to produce a PVDF hollow fiber membrane having protrusions on the surface.

Example 2: Preparation of PVDF hollow fiber membrane having protrusions on its surface

A hollow fiber membrane was prepared in the same manner as in Example 1 except that a donut-shaped plate having 200 projections was used at the lower end thereof.

Example 3: Preparation of PVDF hollow fiber membrane having protrusions on its surface

A hollow fiber membrane was prepared in the same manner as in Example 1 except that a donut-shaped plate having 400 protrusions formed thereon was used.

Example 4: Preparation of PVDF hollow fiber membrane having protrusions on its surface

A hollow fiber membrane was prepared in the same manner as in Example 1 except that a donut-shaped plate having 450 protrusions formed thereon was used.

Comparative Example 1: Preparation of PVDF hollow fiber membrane having no protrusions on its surface

The PVDF hollow fiber membrane was prepared in the same manner as in Example 1 except that the donut-shaped plate having the protrusions was removed.

Experimental Example 1: Surface morphology analysis of the PVDF hollow fiber membrane of the present invention

The surface morphology of the PVDF hollow fiber membrane of the present invention prepared in Example 1 was analyzed by scanning electron microscope (SEM).

The results are shown in Fig.

3, it was confirmed that uniform protrusions were formed on the surface of the PVDF hollow fiber membrane of the present invention to have regular roughened surfaces.

Experimental Example 2: Measurement of physical properties

The permeation flow rate and pore size of the PVDF hollow fiber membranes prepared in Examples 1 to 4 and Comparative Example 1 were measured.

Specifically, the average pore size was measured using a PMI (Permporometer) in this experiment. The pure water permeation flow rate was measured by preparing a module having a certain length and number of strands of the hollow fiber membrane and pressurizing the pure water (20 ° C) in the water tank by 1 kgf / cm ² using an out-In method using a pressure pump.

The results are shown in Table 1 below.

division Average pore size
(탆) Pure permeation amount
(L / m ² hr) Example 1 0.11 412 Example 2 0.10 406 Example 3 0.14 384 Example 4 0.09 375 Comparative Example 1 0.11 394

From the physical property measurement results of Table 1, it can be seen that in Examples 1 to 4 and Comparative Example 1, there is not much difference in average pore size and pure water permeation amount. As a result, it can be seen that the protruding portion protruding from the surface does not greatly affect the physical properties of the hollow fiber membrane.

Experimental Example 3: Measurement of membrane fouling resistance

After measuring the pure permeation flow rate, it was pressurized to 1 kgf / cm ² using Out-In pressure pump with 20 ppm aqueous solution of bovine serum albumin (BSA) And the initial permeate flow rate using the distilled water was compared and expressed as Relative flux using the following equation (1).

[Equation 1]

Relative flux = permeate flow after 6 hours operation / flow rate of distilled water

The membrane fouling resistance was measured using the hollow fiber membranes prepared in Examples 1 to 4 and the hollow fiber membranes prepared in Comparative Example 1, and the results are shown in Table 2 below.

division Relative flux Example 1 0.41 Example 2 0.53 Example 3 0.62 Example 4 0.32 Comparative Example 1 0.12

It can be seen from the above Table 2 that the hollow fiber membrane having the protrusions formed on the surface prepared in Examples 1 to 4 is far superior to the hollow fiber membrane of Comparative Example 1 in pollution resistance. From the above results, it is expected that the hollow fiber membrane manufactured by the manufacturing method of the present invention can be widely used for water treatment such as wastewater and water treatment.

Claims (13)

delete delete delete delete delete delete delete delete delete delete delete delete A multi-tubular nozzle having a first nozzle, ..., and an n-th nozzle (n? 2) in order from the inside to the outside; And
And a donut-shaped plate mounted on a lower end of the multiple tubular nozzle, the plate having an inner circumferential surface and an outer circumferential surface and a projection on the inner circumferential surface,
Wherein the first nozzle emits an internal hole forming agent and the other nozzles except the first nozzle emit a polymer solution having the same or different composition and the protrusion at the lower end of the nth nozzle which is the outermost nozzle The polymer spinning solution corresponding to the outer circumferential surface of the hollow fiber membrane is vortexed to form a hollow fiber membrane by phase transformation of the spinning polymer solution,
The n-th nozzle, which is the outermost nozzle, has an inner circumferential surface and an outer circumferential surface, and a donut-shaped plate having protrusions on the inner circumferential surface is mounted on the lower end of the multiple tubular nozzle. The plate rotates during vigorous spinning to cause swirling of the polymer spinning solution,
The lower end of the n-th nozzle is in contact with the donut-shaped plate, and the lower ends of the first to n-th nozzles are arranged to be parallel to each other,
Wherein the inner circumferential surface of the donut-shaped plate is alternately provided with a protruding portion and a concave portion, the protruding portion and the concave portion being rounded,
Wherein a plurality of projections are continuously or discontinuously formed on the surface in a direction perpendicular or oblique to the longitudinal direction of the hollow fiber membrane.

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