KR20150078595A - Composite Hollow Fiber Membrane and Method for Manufacturing The Same - Google Patents

Abstract

Disclosed are a composite hollow fiber membrane having excellent water permeability and peeling strength while pinhole and defect occurrence in a polymer membrane is minimized, and a manufacturing method thereof. The composite hollow fiber membrane of the present invention includes a tube type polymer foam and a polymer membrane coated on an outer surface of the tube type polymer foam.

Description

Technical Field [0001] The present invention relates to a composite hollow fiber membrane,

More particularly, the present invention relates to a composite hollow fiber membrane having excellent water permeability and peel strength and minimizing the occurrence of pinholes / defects in a polymer membrane, and a method for producing the same.

Examples of the separation method for the fluid treatment include a separation method using heating or phase change, and a separation method using a filtration membrane. The separation method using the filtration membrane has an advantage that the reliability of the process can be improved because the desired water quality can be stably obtained according to the pore size of the filtration membrane. Further, since the filtration membrane does not require operation such as heating, It can be widely used for a separation process using microorganisms that can be received.

Filtration membranes can be classified into flat membranes and hollow fiber membranes depending on their shape.

Hollow fiber membranes with lumens inside are much better than flat membranes in terms of water treatment efficiency because they have much larger surface area than flat membranes. Hollow fiber membranes are widely used in the fields of aseptic water, drinking water, and ultrapure water. In recent years, they have been used for treatment of waste water and wastewater, solid-liquid separation in septic tanks, removal of suspended solid (SS) Filtration of industrial water, filtration of pool water, and the like.

In order for the filtration membrane to be applied to water treatment, it must have a basically excellent permeation performance and an excellent pressure resistance and mechanical strength. However, the hollow fiber membrane has insufficient mechanical strength due to the nature of the porous structure. As part of efforts to increase the mechanical strength of hollow fiber membranes, attempts have been made to reinforce hollow fiber membranes using tubular knitted fabrics.

Examples of composite hollow fiber membranes reinforced with tubular knit fabrics are disclosed, for example, in U.S. Patent No. 6,354,444 and U.S. Patent No. 8,201,485.

U.S. Patent No. 6,354,444 and U.S. Patent No. 8,201,485 disclose a composite hollow fiber membrane produced by coating a polymeric membrane on the outer surface of a tubular knit fabric as a support.

1, when the tubular knitted fabric 110 formed of filaments is used as a support, the mow 111 and / or the loop 112 existing on the outer surface of the tubular knitted fabric 110, May be exposed through the polymer membrane 120 to cause leakage of the composite hollow fiber membrane 100 (that is, the polymer membrane pinhole / defect may occur). Therefore, the presence of the bell 111 and / or the loop 112 adversely affects the pressure resistance and durability of the composite hollow fiber membrane 100.

Accordingly, the present invention relates to a composite hollow fiber membrane capable of preventing problems caused by limitations and disadvantages of the related art and a method of manufacturing the same.

One aspect of the present invention is to provide a composite hollow fiber membrane having excellent water permeability and peel strength and minimizing the occurrence of pinholes / defects in a polymer membrane.

Another aspect of the present invention is to provide a method for producing a composite hollow fiber membrane having excellent water permeability and peel strength and minimizing the occurrence of pinholes / defects in a polymer membrane.

Other features and advantages of the invention will be set forth in the description which follows, or may be learned by those skilled in the art from the description.

According to one aspect of the present invention as described above, a tubular polymer foam; And a polymer membrane coated on the outer surface of the tubular polymer foam.

The tubular polymer foam may be formed of at least one of polyurethane, polyethylene, polypropylene, polystyrene, and polyvinylidene fluoride (PVDF).

The tubular polymer foam is preferably a polyurethane foam having a foaming magnification of 20 to 80 times, a polyethylene foam having a foaming magnification of 10 to 70 times, a polypropylene foam having a foaming magnification of 10 to 70 times, a foaming magnification of 10 to 60 times , And a polyvinylidene fluoride foam having an expansion ratio of 5 to 40 times.

The tubular polymer foam may have an outer diameter of 1.0 to 2.0 mm and a thickness of 0.1 to 0.7 mm.

The polymer membrane may be formed of at least one selected from the group consisting of a polysulfone resin, a polyether sulfone resin, a sulfonated polysulfone resin, a polyvinylidene fluoride (PVDF) resin or a polyacrylonitrile (PAN) resin, a polyimide resin, a polyamideimide resin and a polyesterimide resin Or the like.

According to another aspect of the present invention, there is provided a method of manufacturing a polymer foam, comprising: preparing a tubular polymer foam; And coating a polymer film on the outer surface of the tubular polymer foam.

The preparation of the tubular polymeric foam comprises: preparing a first dope comprising a first polymer; Radiating the first dope through a tubular nozzle; And injecting a gas into the first dope as the first dope passes through the tubular nozzle.

Alternatively, the step of preparing the tubular polymeric foam comprises the steps of: preparing a first dope comprising a first polymer and a pore-forming agent; Radiating the first dope through a tubular nozzle; And removing the pore-former from the first dope.

Alternatively, the preparation of the tubular polymeric foam may comprise the steps of: preparing a first dope comprising a precursor for the first polymer and a foaming agent; Radiating the first dope through a tubular nozzle; And coagulating the emitted first dope.

The step of thermally treating the tubular polymer foam may be further performed before the polymer membrane coating step.

The heat treatment step may be performed at 50 to 200 DEG C for 1 to 60 seconds.

The polymer film coating step may include: preparing a spinning solution containing a second polymer; Passing the tubular polymeric foam through an inner tube of a double tubular nozzle; And radiating the spinning solution through an outer tube of the double tubular nozzle.

The tubular polymer foam may be passed through an oven maintained at 50 to 200 DEG C before the polymer membrane coating step.

The oven passing step and the coating step of the tubular polymer may be performed continuously.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

According to the present invention, it is possible to prevent or minimize the occurrence of leak points because the tubular polymer elastomer does not have any molds and / or loops passing through the polymer membrane coated on its outer surface, Excellent pressure resistance and durability can be obtained.

Further, by using a tubular polymeric elastomer having a certain expansion ratio as a reinforcing material, a composite hollow fiber membrane having excellent water permeability can be provided.

Also, a composite hollow fiber membrane having excellent peel strength can be provided by properly heat-treating the tubular polymer elastomer before coating the polymer membrane on the outer surface of the tubular polymer elastomer.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 schematically shows a cross-section of a conventional composite hollow fiber membrane,
2 schematically shows a cross section of the composite hollow fiber membrane of the present invention,
3 schematically shows a method of manufacturing a tubular polymeric elastomer according to an embodiment of the present invention,
4 schematically shows a method of manufacturing a tubular polymer elastomer according to another embodiment of the present invention,
FIG. 5 schematically shows a method of manufacturing a tubular polymer elastomer according to another embodiment of the present invention,
6 schematically shows a method of coating a polymer membrane on the outer surface of a tubular polymeric elastomer according to an embodiment of the present invention.

Hereinafter, a composite hollow fiber membrane of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

2 schematically shows a cross section of a composite hollow fiber membrane according to the present invention.

As illustrated in FIG. 2, the composite hollow fiber membrane 200 of the present invention includes a tubular polymer foam 210 functioning as a reinforcing material, and a polymer film 220 coated on the surface thereof.

The tubular polymeric foam 210 may be formed of at least one of polyurethane, polyethylene, polypropylene, polystyrene, and polyvinylidene fluoride (PVDF).

The expansion ratio of the tubular polymeric foam 210 may be adjusted to a suitable range for the material forming the tubular polymeric foam 210 considering the effect on the mechanical strength required of the reinforcing material as well as on the water permeability of the composite hollow fiber membrane 200 Should be adjusted. The expansion ratio is calculated by dividing the apparent density of the tubular polymeric foam 210 by the density of the polymer before foaming.

The expansion ratio of the tubular polymeric foam 210 according to an embodiment of the present invention is as follows.

i) Polyurethane foam: 20- to 80-fold expansion ratio

ii) Polyethylene foam: 10- to 70-fold expansion ratio

iii) Polypropylene foam: 10- to 70-fold expansion ratio

iv) Polystyrene foam: 10- to 60-fold expansion ratio

v) Polyvinylidene fluoride foam: 5 to 40 times expansion ratio

The tubular polymer foam 210 according to an embodiment of the present invention has an outer diameter of 1.0 to 2.0 mm. When the outer diameter of the tubular polymer foam 210 is less than 1.0 mm, the inner diameter of the composite hollow fiber membrane 200 becomes excessively small, resulting in a too low permeate flow rate. On the contrary, when the outer diameter of the tubular polymer foam 210 exceeds 2.0 mm, the membrane area of the bundle of composite hollow fiber membranes 200 increases significantly when the cross sections of the bundled composite hollow fiber membranes 200 occupy a certain area Can not be.

In order to increase the membrane area of the composite hollow fiber membrane 200 bundle, it is important to reduce the outer diameter of the tubular polymer foam 210. However, it is also important to reduce the thickness of the tubular polymer foam 210. If the outer diameter of the tubular polymer foam 210 becomes smaller and the inner diameter thereof also becomes smaller proportionally, it is not expected to increase the permeation flow rate of the composite hollow fiber membrane 200.

Thus, according to one embodiment of the present invention, the thickness ratio of the tubular polymeric foam 210 to the outer diameter of the tubular polymeric foam 210 is 15 to 35%.

If the thickness ratio of the tubular polymeric foam 210 to the outer diameter of the tubular polymeric foam 210 exceeds 35%, that is, if the thickness of the tubular polymeric foam 210 is too thick compared to the outer diameter of the tubular polymeric foam 210, The flow of the filtered water flowing along the hollow of the composite hollow fiber membrane 200 is reduced and the amount of the fluid passing through the membrane due to the increase of the thickness of the composite hollow fiber membrane 200 is also reduced.

On the other hand, if the ratio of the thickness of the tubular polymer foam 210 to the outer diameter of the tubular polymer foam 210 is less than 15%, that is, if the thickness of the tubular polymer foam 210 is too thin compared to its outer diameter, The function as the reinforcing material of the polymer foam 210 can not be secured.

Thus, according to one embodiment of the present invention, the tubular polymeric foam 210 has an outer diameter of 1.0 to 2.0 mm and a thickness of 0.1 to 0.7 mm.

In the present invention, the outer diameter, inner diameter and thickness of the tubular polymer foam 210 are measured by the following method.

An FE-SEM microtome is used to cut a tubular polymer foam 210 at an arbitrary point in a longitudinal direction thereof to obtain a cross-sectional sample, and the cross-section is analyzed by FE-SEM. Five samples with a deviation of 20% or less between the longest and shortest lengths of the outer and inner diameters, respectively, are selected. The outer diameter of each selected sample is determined by an average value of the longest outer diameter and the shortest outer diameter, and the inner diameter is determined as an average of the longest inner diameter and the shortest inner diameter. The outer diameter and the inner diameter of the tubular polymer foam 210 are finally obtained by arithmetically averaging the outer diameter and the inner diameter of the five samples, respectively. The thickness (mean thickness) of the tubular polymer foam 210 is the difference between the outer diameter and the inner diameter.

The polymer membrane 220 coated on the outer surface of the tubular polymer foam 210 may be formed of a polymeric material such as a polysulfone resin, a polyethersulfone resin, a sulfonated polysulfone resin, a polyvinylidene fluoride (PVDF) resin, or a polyacrylonitrile PAN) resin, a polyimide resin, a polyamideimide resin, and a polyesterimide resin.

The polymer membrane 220 may be composed of a skin layer having a dense structure and an inner layer having a sponge structure. The skin layer is formed with micropores having a pore size of 0.01 to 1 mu m, and the inner layer has micropores having a pore size of 10 mu m or less, more preferably 5 mu m or less.

In the inner layer of the polymer membrane 220 of the present invention, there are no defective portions exceeding 10 mu m, that is, micropores having a pore size exceeding 10 mu m. If there is a defective area exceeding 10 mu m in the inner layer, the filtration reliability can be greatly reduced. It is more preferable that the pores of the micropores formed in the inner layer of the sponge structure gradually increase toward the center of the composite hollow fiber membrane 200.

According to one embodiment of the present invention, the thickness of the polymer membrane 220 is 0.3 mm or less.

Hereinafter, a method of manufacturing the composite hollow fiber membrane 200 according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 5. FIG.

The method for manufacturing the composite hollow fiber membrane 200 of the present invention includes the steps of preparing a tubular polymer foam 210 and coating the polymer membrane 220 on the outer surface of the tubular polymer foam 210.

The tubular polymeric foam 210 may be continuously produced through extrusion.

Hereinafter, a method of manufacturing the tubular polymer foam 210 according to various embodiments of the present invention will be described in detail with reference to FIGS. 3 to 5. FIG.

According to a first embodiment of the present invention, a first dope comprising a first polymer selected from polyethylene, polypropylene, polystyrene, and polyvinylidene fluoride is prepared. For example, the first dope may be produced by melting the first polymer.

The first dope is then emitted through the tubular nozzle 330, as illustrated in Fig. When the first dope passes through the tubular nozzle 330, an inorganic gas such as a nitrogen gas or a carbon dioxide gas is injected into the first dope to perform foaming.

The radiating first dope is solidified by air cooling to form a tubular polyurethane foam 210.

By controlling the injection amount of the inorganic gas and / or the injection speed, the expansion ratio of the finally obtained tubular polymeric foam 210 can be controlled.

According to a second embodiment of the present invention, a first dope comprising a first polymer selected from polyethylene, polypropylene, polystyrene, and polyvinylidene fluoride and a pore-former is prepared. For example, the first dope may be prepared by melting the first polymer and then adding a pore-forming agent.

The first dope is then emitted through the tubular nozzle 310, as illustrated in Fig. The emitted first dope passes through the coagulation liquid 322 in the coagulation tank 321, the pore forming agent is removed, and the first dope is solidified to form a tubular polyurethane foam 210.

The coagulating solution 322 is preferably a solution suitable for elution of the pore-forming agent. For example, when the pore former is a polymer such as poly (alkylene carbonate), poly (alkylene oxide), poly (dialkylsiloxane), acrylic resin, etc., the coagulating solution is an organic solvent, and the pore- , Potassium carbonate, sodium carbonate, lithium chloride and the like, the solidification can be carried out through water.

The expansion ratio of the finally obtained tubular polymeric foam 210 can be controlled by controlling the content of the pore-forming agent in the first coating.

According to the third embodiment of the present invention, first a first dope including the first polymer precursor and the foaming agent is prepared. The first polymer may be polyurethane. For example, the first dope can be prepared by mixing a polyol, a diisocyanate, a catalyst, a foam stabilizer, a crosslinking agent, and a foaming agent.

The polyol may be a polyether polyol or a polyester polyol. Specifically, polyethylene oxide (PEO), polyethylene glycol (PEG), polypropylene glycol (PPG), and the like can be used as the polyol.

The diisocyanate may be toluene diisocyanate, methylenediphenyl diisocyanate, 1,6-hexamethylene diisocyanate, or isophorone diisocyanate.

The polyol and the diisocyanate may be used in the range of 60 to 130, preferably 80 to 120, in terms of the isocyanate equivalent / polyol equivalent percentage index.

The catalyst may be an amine catalyst or a mixed catalyst of an amine catalyst and a tin catalyst, and may be contained in an amount of 0.2 to 3.5% by weight in the first dope.

The foam stabilizer may be a silicone surfactant for lowering the surface tension of the foam and increasing the mixing property, and may be contained in an amount of 0.2 to 3.5% by weight in the first dope.

The cross-linking agent may be a diol, a triol, or a diamine in order to accelerate a cross-linking reaction for forming a polymer. The cross-linking agent may be contained in the first dope in an amount of 0.2 to 3.5% by weight.

The foaming agent acts to expand the foam by causing foaming in the urethane reaction process. The blowing agent is preferably used in an amount of from about 0.1 to about 10 parts by weight based on 100 parts by weight of water, azodicarbonamide (ADCA), methylene chloride, liquid carbon dioxide, n-pentane, isopentane, hydrogenated chlorofluorocarbon), and may be contained in an amount of 0.5 to 20% by weight in the first dope.

Then, as illustrated in FIG. 5, the first dope is radiated through the tubular nozzle 310, and the radiated first dope is solidified to form the tubular polymer foam 210. [

By controlling the content of the foaming agent in the first coating, the foaming magnification of the tubular polymer foam 210 can be adjusted to 20 to 80 times.

Once the tubular polymer foam 210 is prepared as described above, a step of coating the polymer membrane 220 on its outer surface is performed. The coating step may be performed using a double tubular nozzle.

The step of heat-treating the tubular polymeric foam 210 may be further performed before the step of coating the polymeric membrane 220. The heat treatment step may be performed at 50 to 200 DEG C for 1 to 60 seconds.

Hereinafter, a method of coating the polymer membrane 220 according to an embodiment of the present invention will be described in detail with reference to FIG.

First, a spinning solution containing the second polymer is prepared. Wherein the second polymer is selected from the group consisting of a polysulfone resin, a polyether sulfone resin, a sulfonated polysulfone resin, a polyvinylidene fluoride (PVDF) resin or a polyacrylonitrile (PAN) resin, a polyimide resin, a polyamideimide resin, Ester imide.

The spinning solution is prepared by dissolving polyvinylpyrrolidone and / or a hydrophilic compound, which is an additive, together with the second polymer in an organic solvent. The spinning solution may contain 10 to 50 wt% of a second polymer, 1 to 30 wt% of an additive (polyvinylpyrrolidone and / or hydrophilic compound), and 20 to 89 wt% of an organic solvent.

As the organic solvent, dimethylacetamide, dimethylformamide or a mixture thereof may be used.

As the hydrophilic compound, water or a glycol compound, more preferably polyethylene glycol having a molecular weight of 2,000 or less, may be used. Since the hydrophilic compound serves to lower the stability of the spinning solution, the possibility that the sponge-like structure is expressed in the polymer membrane 220 relatively increases. That is, as the stability of the spinning solution is higher, a defective site (micropores having an pore size exceeding 10 mu m) is formed in the polymer membrane 220 and a finger-like structure is easily formed. Thus, water or glycols The addition of a hydrophilic compound such as a compound decreases the stability of the spinning solution and at the same time increases the water permeability of the composite hollow fiber membrane 200 by making the polymer membrane 220 hydrophilic.

6, in order to apply the spinning solution on the outer surface of the tubular polymer foam 210, the tubular polymer foam 210 is passed through an oven 410 maintained at 50 to 200 ° C And then passes through the inner tube of the double tubular nozzle 420.

When the tubular polymer foam 210 passes through the inner tube of the double tubular nozzle 420, the spinning solution is radiated through the outer tube of the tubular tubular nozzle 420 so that the spinning solution flows into the tubular polymer foam 210 ). ≪ / RTI >

Then, the applied spinning solution is discharged from the double tubular nozzle 420 together with the tubular polymer foam 210 into the air, and solidified in the coagulating liquid. Then, the washing and drying steps are performed sequentially.

In order to uniformly coat the polymer membrane 220 on the outer surface of the tubular polymer foam 210 to a uniform thickness, it is necessary to balance the traveling speed of the tubular polymer foam 210 and the amount of spinning solution flowing into the outer tube of the tubular nozzle 420 And the relation expressed by the supply rate Q of the spinning solution and the velocity (v) of the tubular polymer foam 210 is as follows.

Where Q is the amount of spinning solution supplied per hour, ρ is the density of the spinning solution, v is the speed of tubular polymer foam, D _o is the outer diameter of the tubular polymeric foam, and T is the thickness of the coating solution to be coated.

As can be seen from the above equation, the thickness of the polymer membrane 220 can be controlled by using the supply amount of the spinning solution, the density of the spinning solution, the advancing speed of the tubular polymer foam 210, and the like.

The step of passing the tubular polymer foam 210 through the oven 410 and the coating step using the double tubular nozzle 420 are preferably performed continuously. Since the polymer membrane 220 is coated on the outer surface immediately after the tubular polymer foam 210 is heat-treated at 50 to 200 ° C, the composite hollow fiber membrane 200 of the present invention exhibits a low heat shrinkage rate of 3% or less In addition, the adhesion between the tubular polymeric foam 210 and the polymer membrane 220 is strengthened to exhibit excellent peel strength of 1 to 5 MPa.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

Manufacture of stiffeners

Example  One

(TDI), 0.3% by weight of an amine catalyst, 0.8% by weight of a foaming agent (silicone surfactant), 0.5% by weight of a crosslinking agent (triol), 46% by weight of polyethylene glycol (PEG), 51% by weight of toluene diisocyanate And 1.5% by weight of a blowing agent (water). The percentage index of TDI equivalents / PEG equivalents was 110.

Then, the first dope was radiated through a tubular nozzle and then solidified by an air cooling method, thereby completing a tubular polymer foam having an outer diameter of 1.3 mm, a thickness of 0.2 mm and an expansion ratio of 50 times.

Example  2

The first dope was prepared by melting polyethylene. Then, the first dope was radiated through the tubular nozzle, and the foaming process was performed by injecting nitrogen gas into the first dope as the first dope passed through the tubular nozzle. By solidification by air cooling, a tubular polyurethane foam having an outer diameter of 1.4 mm, a thickness of 0.3 mm and an expansion ratio of 50 times was completed.

Example  3

After the polyethylene was melted, a first dope was prepared by adding lithium chloride as a pore former. Then, the first dope was radiated through the tubular nozzle. The first dope discharged into the air passes through water to remove the pore forming agent and at the same time the first dope is solidified to complete tubular polyurethane foam having an outer diameter of 1.3 mm, a thickness of 0.2 mm and a foaming magnification of 40 times .

Comparative Example 1

A yarn was produced by joining two filaments composed of 200 filament monofilaments having a fineness of 0.31 denier and one filament having 72 filament monofilaments having a fineness of 2 denier. Using these 20 yarns, a tubular knitted fabric having an outer diameter of 1.7 mm and a thickness of 0.4 mm was produced.

Comparative Example  2

Six filament filaments consisting of 200 PET monofilaments with a fineness of 0.31 denier were folded together to produce yarns. Using these 20 yarns, a tubular knitted fabric having an outer diameter of 1.9 mm and a thickness of 0.6 mm was produced.

Preparation of composite hollow fiber membrane

Example  4

17% by weight of polyvinylidene fluoride (PVDF), 9% by weight of polyvinylpyrrolidone and 10% by weight of polyethylene glycol were dissolved in 64% by weight of dimethylformamide (organic solvent) while stirring to prepare a transparent decanter. Next, the spinning solution was supplied to a double tubular nozzle including an outer tube (diameter: 2.38 mm) of a double tubular nozzle, and the tubular polymer foam produced according to Example 1 was passed through the inner tubular tube of the double tubular nozzle, The outer surface of the polymer foam was coated with a spinning solution, which was then discharged into the air. At this time, the progress speed ratio (k) of the tubular polymer foam to the supply rate of the spinning solution was set to 750 g / m 2. The tubular polymer foam coated with the spinning solution was passed through an air gap of 10 cm, and then passed through a coagulation tank and a washing tank at 35 ° C in order and wound to produce a composite hollow fiber membrane. The polymer membrane coated on the tubular polymer foam had a thickness of 0.2 mm.

Example  5

A composite hollow fiber membrane was prepared in the same manner as in Example 4, except that the tubular polymer foam prepared in Example 2 was used in place of the tubular polymer foam prepared in Example 1.

Example  6

A composite hollow fiber membrane was prepared in the same manner as in Example 4, except that the tubular polymer foam prepared in Example 3 was used in place of the tubular polymer foam prepared in Example 1.

Example  7

A composite hollow fiber membrane was prepared in the same manner as in Example 4, except that the tubular polymer foam was heat-treated at 120 ° C for 30 seconds by passing it through an oven just before passing through the inner tubular portion of the double tubular nozzle.

Comparative Example  3

A composite hollow fiber membrane was prepared in the same manner as in Example 4, except that the tubular polymer fabricated in Example 1 was replaced by the tubular fabric fabricated in Comparative Example 1, instead of the tubular polymer foam.

Comparative Example  4

A composite hollow fiber membrane was prepared in the same manner as in Example 4 except that a tubular knitted fabric manufactured by Comparative Example 2 was used in place of the tubular polymer foam prepared in Example 1.

The water permeability, membrane integrity and peel strength of the composite hollow fiber membranes prepared in Examples 4 to 7 and Comparative Examples 3 and 4 were determined by the following methods, respectively, and the results are shown in Table 1 below.

Water permeability ( Lp )

An acrylic tube having a diameter of 10 mm and a length of 170 mm and four composite hollow fiber membranes were prepared. The composite hollow fiber membrane was cut into a length of 160 mm, and one end thereof was sealed with an adhesive. The composite hollow fiber membrane was placed in the acrylic tube and then sealed between the one end of the acrylic tube and the composite hollow fiber membrane. Next, pure water was placed in an acrylic tube, and a nitrogen pressure was applied to measure the amount of pure water permeating the composite hollow fiber membrane for 1 minute. The unit of the water permeability (Lp) is ml / (cm ² x min x kg / cm ² ).

Membrane integrity ( Bubble Point )

500 strands of the composite hollow fiber membrane were cut to a length of 4 m and then kept in a U shape to fix the cut portion with an adhesive. The U-shaped composite hollow fiber membrane was immersed in a water bath. Water was sucked through the section of the membrane fixed with an adhesive for 30 minutes by using a pump, and then the pressure of nitrogen was raised for 3 minutes while the pressure was increased by 0.1 kg / cm ² . At this time, the pressure at which bubbles were generated on the surface of the film was recorded.

Peel strength

The moment when the polymer membrane was peeled off from the stiffener was measured using a tensile tester, and the peel strength was calculated by dividing by the area (m ² ) where the shear force was applied. The specific measurement conditions are as follows.

- Measuring instrument: Instron 4303

- Load Cell: 1KN

- Crosshead Speed: 25 mm / min

- Finger distance: 50mm

- Specimen: A polypropylene tube having a diameter of 6 mm was prepared by bonding one strand of a composite hollow fiber membrane with a polyurethane resin so that the length of the bonded portion was 10 cm.

* Peel strength (Pa) = load at yield point (kg) / area applied by shear force (m ² )

The peel strength is defined as the shear strength per unit area applied to the coated polymer membrane when the specimen is tensioned and the area (m ² ) to which the shear force is applied is "π × outer diameter of the composite hollow fiber membrane (m) (M) "

reinforcement Composite hollow fiber membrane Kinds
(Expansion ratio / filament) Outer diameter
(mm) thickness
(mm) Heat treatment
Whether Water permeability
(Lp) Bubble Point
(kg / cm ² ) Peel strength
(Mpa) Example 4 PU foam (50 times) 1.3 0.2 × 3.3 1.5 1.2 Example 5 PE foam (50 times) 1.4 0.3 × 2.7 1.3 1.3 Example 6 PE foam (40 times) 1.3 0.2 × 2.5 1.3 1.0 Example 7 PU foam (50 times) 1.3 0.2 ○ 2.5 1.8 1.5 Comparative Example 1 Tubular knitted fabric (three fineness + fineness) 1.7 0.4 × 3.0 1.0 1.5 Comparative Example 2 Tubular knitted fabric (three islands) 1.9 0.6 × 2.0 0.7 1.8

200: composite hollow fiber membrane 210: tubular polymer foam
220: polymer membrane 310, 330: tubular nozzle
321: Coagulation bath 322: Coagulation solution
410: oven 420: double tubular nozzle

Claims (14)

Tubular polymeric foam; And
The polymer film coated on the outer surface of the tubular polymer foam
Wherein the composite hollow fiber membrane comprises a hollow fiber membrane. The method according to claim 1,
Wherein the tubular polymer foam is formed of at least one of polyurethane, polyethylene, polypropylene, polystyrene, and polyvinylidene fluoride (PVDF). The method according to claim 1,
The tubular polymer foam is preferably a polyurethane foam having a foaming magnification of 20 to 80 times, a polyethylene foam having a foaming magnification of 10 to 70 times, a polypropylene foam having a foaming magnification of 10 to 70 times, a foaming magnification of 10 to 60 times , And a polyvinylidene fluoride foam having an expansion ratio of 5 to 40 times. The composite hollow fiber membrane according to claim 1, wherein the polyvinylidene fluoride foam is a polyvinylidene fluoride foam. The method according to claim 1,
Wherein the tubular polymer foam has an outer diameter of 1.0 to 2.0 mm and a thickness of 0.1 to 0.7 mm. The method according to claim 1,
The polymer membrane may be formed of at least one selected from the group consisting of a polysulfone resin, a polyether sulfone resin, a sulfonated polysulfone resin, a polyvinylidene fluoride (PVDF) resin or a polyacrylonitrile (PAN) resin, a polyimide resin, a polyamideimide resin and a polyesterimide resin Wherein the hollow fiber membrane comprises at least one of the following. Preparing a tubular polymer foam; And
Coating the polymer membrane on the outer surface of the tubular polymer foam;
Wherein the hollow fiber membrane has a thickness of 10 mm or less. The method according to claim 6,
In preparing the tubular polymer foam,
Preparing a first dope comprising a first polymer;
Radiating the first dope through a tubular nozzle; And
And injecting gas into the first dope as the first dope passes through the tubular nozzle. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
In preparing the tubular polymer foam,
Preparing a first dope comprising a first polymer and a pore-forming agent;
Radiating the first dope through a tubular nozzle; And
And removing the pore-forming agent from the radiated first dope. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
In preparing the tubular polymer foam,
Preparing a first dope comprising a precursor for the first polymer and a foaming agent;
Radiating the first dope through a tubular nozzle; And
And coagulating the irradiated first dope. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
The method of manufacturing a composite hollow fiber membrane according to claim 1, further comprising the step of heat treating the tubular polymer foam before the polymer membrane coating step. 11. The method of claim 10,
Wherein the heat treatment step is performed at 50 to 200 DEG C for 1 to 60 seconds. 10. The method according to any one of claims 7 to 9,
In the polymer membrane coating step,
Preparing a spinning solution containing the second polymer;
Passing the tubular polymeric foam through an inner tube of a double tubular nozzle; And
And spinning the spinning solution through the outer tube of the double tubular nozzle. 13. The method of claim 12,
Further comprising the step of passing the tubular polymer foam through an oven maintained at 50 to 200 DEG C before the polymer membrane coating step. 14. The method of claim 13,
Wherein the oven passing step and the coating step of the tubular polymer are continuously performed.

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