WO2012128470A2 - Polysulfone-based hollow fiber film having excellent strength and water permeability, and method for manufacturing same - Google Patents

Abstract

The present invention relates to a polysulfone-based hollow fiber film having 20-25 wt% of a polysulfone resin (A), 45-55 wt% of an organic solvent (B), and 30-35 wt% of a hydrophilic additive (C), the hollow fiber film having an asymmetric sponge structure, in which pore sizes increase continuously going from an outer surface layer to an inner surface layer, and the ratio of the pore sizes of the outer surface layer and the inner surface layer is 1:10-1:10000, and a method for manufacturing the polysulfone-based hollow fiber film comprises the steps of: preparing a spinning undiluted solution including a polysulfone-based resin (A), an organic solvent (B), and a hydrophilic additive (C); preparing an inner coagulant; spinning the spinning undiluted solution and the inner coagulant; forming pores; and winding, wherein the step for forming the pores is spun when the total retention time in the coagulation set and washing set exceeds 90 seconds.

Description

Polysulfone hollow fiber membrane with excellent strength and water permeability and its manufacturing method

The present invention relates to a hollow fiber membrane and a method for manufacturing the same, and more particularly, to a polysulfone-based hollow fiber membrane and a method of manufacturing the improved water permeability and strength.

Separation membrane refers to a material having a selective permeability to separate the undissolved particles from the fluid. The membrane is divided into two types: flat membrane and hollow fiber membrane. Hollow fiber membranes are most used for water treatment because they have high filtration efficiency within the same volume.

Hollow fiber membranes can be classified into two types according to the manufacturing method, which can be broadly classified into nonsolvent induced phase preparation process (NIPS) method using non-solvent and thermally induced phase preparation process (TIPS) method manufactured using heat. have.

The membrane prepared by the NIPS method can give a variety of changes to the spinning conditions to form a variety of structures, particularly asymmetrical structure of the membrane, it is easy to adjust the pore size by adding various additives, hydrophilization to the membrane There is an advantage to obtain a high water permeability by imparting, but generally has a disadvantage of weak strength.

On the other hand, the separator prepared by the TIPS method is generally the same structure on the outside and inside the surface of the separator, the high strength of the separator can be widely used mainly in the industry. In particular, recently, fluorine-based polymers have been introduced and applied to fluorine-based hollow fiber membranes having excellent strength. The TIPS method has the advantage of obtaining high strength properties, but it is difficult to control pore size easily and difficult to solution hydrophobic and hydrophilic additives of fluorine-based polymers. Has a problem of falling.

The general characteristics required for hollow fiber membranes for water treatment are as follows. First of all, the characteristics affecting the separation function are appropriate porosity (number of empty holes) for the purpose of separation efficiency, uniform pore distribution for the purpose of improving the fractional accuracy, and optimum pore size to effectively separate the separation object. To be required. Next, as material properties, chemical resistance, chemical resistance, heat resistance, etc. to chemical treatment are required. In addition, there is a need for excellent mechanical strength and water permeability associated with operating costs to extend the service life due to characteristics affecting the driving ability.

Polysulfone hollow fiber membranes developed in the prior art have a high water permeability due to relatively hydrophilic material characteristics than fluorinated resins, but due to the low mechanical strength, periodic backwashing is required, which is problematic for industrial use. Is being used by.

Therefore, in recent years, research has been actively conducted on vinylidene fluoride-based hollow fiber membranes, which are fluorine-based resins having mechanical strength superior to those of polysulfone-based resins. However, due to the non-adhesiveness and the lowering of the compatibility, the moldability is not good, and because of the hydrophobicity, the water permeability is significantly low.

In order to solve the above problems, US Patent No. 4,871,494 has been attempted to increase the concentration of the polymer when the polysulfone-based membrane is manufactured by the NIPS method to increase the concentration of the macropore to increase the strength, but the water permeability It can be seen that the degradation of the membrane performance.

As another method, Korean Patent No. 129816 discloses a membrane manufacturing process in which a spinning nozzle is modified to use a triple nozzle, and a polymer solution composition and solidification rate are controlled to suppress macropores to enhance strength. The triple nozzle has a disadvantage in that the manufacturing method is more complicated than a single nozzle, and the manufacturing cost is high due to supplementation of additional equipment.

In addition, as in the recent Korean Patent Application No. 2010-0078481, the separator was made of only fine micropores without macropores by controlling the spinning conditions without changing the composition and ratio of the spinning solution or introducing additional processes. It can be seen that the permeability is not significantly superior to the conventional membrane.

On the other hand, the research group of the present inventors invented an industrial hollow fiber membrane which maintains excellent permeability by using a polysulfone polymer having good hydrophilicity and enhanced the weak mechanical strength of the conventional polysulfone polymer.

An object of the present invention is to provide a polysulfone-based hollow fiber membrane having excellent strength and water permeability.

Another object of the present invention is to provide a method for producing a polysulfone hollow fiber membrane having excellent strength and water permeability.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to solve the above technical problem, according to an embodiment of the present invention, the present invention is 20 to 25% by weight of a polysulfone resin (A), 40 to 50% by weight of an organic solvent (B) and a hydrophilic additive (C) 30 A polysulfone hollow fiber membrane comprising 35% by weight, wherein the hollow fiber membrane is an asymmetric sponge structure in which the pore size is continuously increased from the outer surface layer to the inner surface layer, and the ratio of the pore sizes of the outer surface layer and the inner surface layer is 1: It provides a polysulfone hollow fiber membrane, characterized in that 10 to 1: 10000.

According to another embodiment of the present invention, the polysulfone hollow fiber membrane has a strength of 800 gf / 本 or more and a water permeability of 2,000 L / m ² * kgf * h.

According to another embodiment of the present invention, the polysulfone resin (A) is polysulfone or polyisulfone, the organic solvent (B) is dimethyl acetamide (dimethylacetamide, DMAc), dimethyl formamide (DMF), Chloroform, N-methyl-2-pyrrolidone (NMP / N-Methyl-2-Pyrrolidone), dimethyl sulfoxide (Dimethylsulfoxide), and mixtures thereof, and the hydrophilic additive (C) Polyvinylpyrrolidone (weight average molecular weight Mw: 15,000 to 90,000), polyethylene glycol (Mw: 200 to 1,000), ethylene glycol, methyl alcohol, glycerin, cellulose acetate, polyvinyl alcohol, sodium chloride, lithium chloride, polypropylene And glycol, castor oil, zinc chloride, and mixtures thereof.

In order to solve the other technical problem of the present invention, according to one embodiment of the present invention, the present invention is prepared a spinning solution containing a polysulfone resin (A), an organic solvent (B), and a hydrophilic additive (C) Doing; Preparing an internal coagulating solution; Spinning the spinning stock solution and the internal coagulating solution through a double nozzle; Forming organic pores by phase-conversion with the nonsolvent in the coagulation bath and the cleaning bath by the organic solvent (B) and the hydrophilic additive (C); And a winding step, wherein the forming of the pores provides a method for producing a polysulfone-based hollow fiber membrane, wherein the total residence time in the coagulation bath and the cleaning bath is radiated in excess of 90 seconds.

According to another embodiment of the invention, the residence time in the coagulation bath of the spinning step is characterized in that more than 15 seconds.

According to another embodiment of the present invention, the coagulation bath temperature of the spinning step is characterized in that 50 to 70 ℃.

Other specific details of embodiments of the present invention are included in the following detailed description.

The present invention provides a polysulfone hollow fiber membrane having an asymmetric sponge structure in which no pinholes or finger structures are formed and the pores of the inner surface layer are larger than the outer surface layer, and the hollow fiber membrane of the present invention has excellent water permeability and strength.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The manufacturing equipment process schematic diagram of a hollow fiber membrane.

2 illustrates the principle of structure formation according to the phase switching speed.

FIG. 3 is an electrophotograph obtained by magnifying a cross section of the hollow fiber membrane according to Example 2 with a scanning electron microscope 50 times. FIG.

Figure 4 is an electrophotographic measurement of the inner surface of the hollow fiber membrane according to Example 2 magnified 90 times with a scanning electron microscope.

5 is an electrophotographic image of an outer surface of a hollow fiber membrane according to Example 2, at 30,000 times magnification, measured by a scanning electron microscope.

FIG. 6 is an electrophotograph obtained by magnifying a cross section of a hollow fiber membrane according to Example 3 with a scanning electron microscope 400 times. FIG.

FIG. 7 is an electrophotographic image of the inner surface of a hollow fiber membrane according to Example 3 at 90 times magnification with a scanning electron microscope. FIG.

8 is an electrophotographic image of an outer surface of a hollow fiber membrane according to Example 3, at 30,000 times magnification, measured by a scanning electron microscope.

FIG. 9 is an electrophotograph obtained by magnifying a cross section of a hollow fiber membrane according to Comparative Example 7 with a scanning electron microscope.

10 is an electrophotographic image of the inner surface of a hollow fiber membrane according to Comparative Example 7 at 90 times magnification with a scanning electron microscope.

11 is an electrophotographic measurement of an outer surface of a hollow fiber membrane according to Comparative Example 7 magnified 30,000 times with a scanning electron microscope.

Explanation of the sign

1. Dopant Manufacturing Tank

2. Internal coagulant manufacturing tank

3. Gear Pump

4. Double tube nozzle

5. Coagulation tank

6. Godet Roller

7. Guide Roller

8. Flush tank

9. Tension control device

10. Traverse

11.winder

12. Winding tank

Hereinafter, the present invention will be described in more detail.

Polysulfone Hollow Fiber Membrane

Polysulfone hollow fiber membrane of the present invention is a spinning solution containing 20 to 25% by weight of polysulfone resin (A), 40 to 50% by weight of an organic solvent (B), and 30 to 35% by weight of a hydrophilic additive (C) and It is a feature of the invention to be produced by spinning the internal coagulating solution.

Polysulfone Resin (A)

As the polysulfone resin of the present invention, polysulfone, polyethersulfon, and mixtures thereof may be used as the base resin. Polysulfone resins have the advantages of excellent chemical resistance and heat resistance, wide pH range applied, and excellent solubility in organic solvents, making it easy to prepare a spinning solution (dope).

The polysulfone resin (A) is preferably included in 20 to 25% by weight relative to the total weight of the spinning solution. When the polysulfone resin is 20 wt% or less, the hollow fiber is not formed due to the low viscosity, and it is difficult to control the air gap, resulting in poor radioactivity. When the polysulfone resin is 25 wt% or more, the solubility in the spinning stock solution is decreased. May occur or the appearance may be uneven.

Organic solvent (B)

The organic solvent (B) of the present invention used to dissolve the polysulfone resin (A) is dimethyl acetamide (dimethylacetamide, DMAc), dimethyl formamide (DMF), chloroform, N-methyl-2- It is preferable to use one or more selected from the group consisting of pyrrolidone (N-Methyl-2-Pyrrolidone) and dimethyl sulfoxide (Dimethylsulfoxide). The organic solvent is contained in 30 to 60% by weight, preferably 40 to 50% by weight relative to the total weight of the spinning solution.

Hydrophilic Additives (C)

The present invention includes a hydrophilic additive to impart hydrophilization or control the pore size to the hollow fiber to be produced. Examples of the hydrophilic additive include polyvinylpyrrolidone (weight average molecular weight Mw: 15,000 to 90,000), polyethylene glycol (Mw: 200 to 1,000), ethylene glycol, methyl alcohol, glycerin, cellulose acetate, polyvinyl alcohol, sodium chloride, chloride Hydrophilic additives such as lithium, polypropylene glycol, castor oil, and zinc chloride.

The hydrophilic additives affect the pore formation and hydrophilicity of the hollow fiber and are closely related to the water permeability. More specifically, the hydrophilic additive present in the spinning solution during the stay in the coagulation bath after the spinning solution is discharged from the double-tubular nozzle may absorb the non-solvent of the coagulation bath, thereby facilitating phase inversion with the solvent of the spinning solution. In addition, the hydrophilic additive acts as a swelling agent to increase the pore size, or cross-linkage of the hydrophilic group in the polysulfone resin to increase the hydrophilicity of the hollow fiber.

The hydrophilic additive (C) is contained in 10 to 40% by weight, preferably 20 to 35% by weight relative to the total weight of the spinning solution. When the content of the hydrophilic additive (C) is less than 10% by weight, pores are not formed inside the hollow fiber, so that the water permeability is remarkably lowered. In particular, as illustrated in FIG. 9, a finger-like structure may be formed. Can be. On the other hand, when it is included in more than 40% by weight as shown in Figure 6, the large pores (Pin-Hole) is formed may be reduced durability and pressure resistance.

Method for manufacturing polysulfone hollow fiber membrane

Method for producing a polysulfone hollow fiber membrane of the present invention comprises the steps of preparing a spinning stock solution containing a polysulfone resin (A), an organic solvent (B), and a hydrophilic additive (C); Preparing an internal coagulating solution; Spinning the spinning stock solution and the internal coagulating solution through a double nozzle; Forming organic pores by phase-conversion with the nonsolvent in the coagulation bath and the cleaning bath by the organic solvent (B) and the hydrophilic additive (C); And a winding step.

Preparation of the spinning stock:

As described above, the polysulfone resin (A), the organic solvent (B), and the hydrophilic additive (C) are dissolved at a compounding temperature of 30 to 40 ° C. and a stirring speed of 80 to 120 rpm for 12 to 24 hours, and then -5 to Degassing under a vacuum of -1 kgf for 12 to 24 hours to remove bubbles in the spinning stock solution (DOPE).

Internal coagulation preparation steps:

The internal coagulation solution is used to form pores inside the hollow fiber membrane, and the solvent is dimethyl acetamide (DMAc), dimethyl formamide (DMF), chloroform, tetrahydrofuran, N in non-solvent water. Prepare by mixing with methyl-2-pyrrolidone (N-Methyl-2-Pyrrolidone), dimethylsulfoxide or mixtures thereof.

The blending ratio is formulated in an amount of 0 to 30% by weight, preferably 5 to 25% by weight, and 70 to 100% by weight, preferably 75 to 95% by weight, of an organic solvent. The mixing temperature of the internal coagulation solution is 50 to 70 ℃, the stirring speed is mixed for 12 to 24 hours at 80 to 120 rpm, and then degassed for 6 to 12 hours under a vacuum of -5 to -1 kgf bubbles in the core (Core) Remove it.

Spinning step and pore forming step:

The spinning equipment used in the spinning step of the spinning stock solution and the internal coagulating solution is a spinning stock solution (Dope) and internal coagulating solution (Core) manufacturing tank, nozzle holder, primary coagulation tank, washing tank, winding tank, and the specimen after the spinning finish (Sample) is composed of a washing tank for removing the residual organic solvent, more specifically the spinning process schematic diagram of the present invention related to this is shown as an example in FIG.

The radiation source solution (Dope) and the internal coagulation solution (Core) production tank, nozzle holder process line to build a fruit system can be controlled and maintained in the temperature range of 25 to 200 ℃.

The nozzle holder is manufactured to be movable up, down, left, and right to adjust an air gap between the nozzle and the coagulation bath. The air gap is a section in which the primary phase change occurs, and the phase change is performed by exchanging the organic solvent in the atmospheric moisture and the radiation source solution.

The coagulation bath is installed with a multi-stage Gorod Roller in the coagulation bath to extend the phase change time to the place where the secondary phase conversion occurs to extend the residence time of the membrane. In addition, the residence time can be adjusted by providing a multi-stage high roller in the cleaning tank.

The residence time of the coagulation bath is more than 10 seconds, preferably 15 seconds or more. If the residence time of the coagulation bath is less than 10 seconds, the secondary phase inversion is not sufficiently achieved, the pore formation is lowered and the water permeability falls.

The residence time of the washing tank is 80 seconds or more, preferably 90 seconds or more. Retention step of the washing tank is a third phase conversion process and the washing of the internal coagulant is carried out in which the phase change of the spinning stock solution is not completed in the coagulation tank. If the residence time of the cleaning tank is less than 80 seconds, there is a problem that residual organic solvent remains because the washing of the additive and the internal coagulant is not complete.

Therefore, the total residence time of the coagulation bath and the washing bath is 90 seconds or more, preferably 105 seconds or more. The longer the total residence time, the better the phase conversion and cleaning, but the longer the production process, the lower the productivity.

As a specific spinning process conditions, the hollow yarn is discharged by spinning the prepared spinning stock solution and the internal coagulating solution using a double-tubular nozzle, and a primary phase conversion is performed in an air gap. Secondary phase transitions are then made through the coagulation bath. After removing the additives and the residual organic solvent in the washing tank is transported to the take-up tank, the spinning process is completed.

The length of the air gap is 10 cm or less, preferably 1 to 5 cm. If the air gap exceeds 10 cm, the primary phase of the organic solvent in the atmospheric water vapor and DOPE is sufficient to increase the porosity and increase the water permeability, but the hollow fiber twist or single yarn Such as radioactivity may be lowered. On the other hand, if there is no air gap, the radioactivity is excellent, but since the second phase inversion is performed immediately without the first phase inversion, the porosity is lowered, which may cause a problem of decreasing the water permeability.

Phase conversion is the principle that the organic solvent and hydrophilization additive in the radiation source solution (DOPE) are taken out, and the voids are filled with the non-solvent in the external coagulation bath to form pores. The higher the temperature of the external coagulation bath, the faster the phase conversion. This is done quickly to form a sponge structure. However, when the temperature of the external coagulation bath is excessively high, exceeding 70 ℃, the atmospheric humidity is oversaturated, so that single yarns occur, the radioactivity may be lowered, or the working environment may be poor. On the other hand, when the temperature of the external coagulation bath is lower than 30 ° C., only the outer surface where the radiation source solution contacts the non-solvent is phase-shifted, and the organic solvent and additives inside do not escape and stay out at once. Pores are formed to form a finger-like structure. More specifically, the structure formation principle according to the phase switching speed is shown in FIG. 2. As shown in the table of FIG. 2, the permeation rate of the non-solvent refers to the rate at which the ultrapure water of the coagulation bath penetrates into the spinning solution, and the permeation rate of the solvent refers to the speed at which the solvent inside the spinning solution flows out into the coagulation bath. That is, the sponge structure can be formed only if the ultrapure water of the coagulation bath rapidly penetrates into the spinning solution. As described above, the higher the temperature of the coagulation bath, the higher the permeation rate and the phase change rate is also increased.

In the present invention, in order to form a sponge structure in the formation of the hollow yarns and to prevent the formation of the finger structure, the coagulation bath and the washing tank water is filled with water or a mixture of water and an organic solvent, the temperature is 30 to 80 ℃, more preferably 50 Maintaining at from 70 to 70 ℃ is characterized by the invention.

Structure of Polysulfone Hollow Fiber Membrane

In general, the cross section of the hollow fiber for water treatment can be largely divided into a finger structure and a sponge structure. FIG. 6 illustrates a finger structure. Referring to this, the outermost layer (skin layer) is formed into a dense structure, and the water permeability is remarkably inferior. This is because it melts and forms large pores in the cross section, and thus the pressure resistance is weakened, and when the external surface leaks, contaminants pass through as they are and thus do not function as a separation membrane. In addition, the sponge structure may be divided into a symmetric membrane structure and an asymmetric membrane structure, the symmetric membrane structure is a structure with the same pore size of the outer surface and the inner surface, the asymmetric membrane structure is a structure having a different pore size of the outer surface and the inner surface It can be defined as. 3 illustrates a symmetric membrane structure as an example of a sponge structure. The asymmetric membrane has the advantage of having a high channel resistance compared to the symmetric membrane with less flow resistance. In addition, the cross-sectional structure is formed in a compact structure than the finger structure is excellent in pressure resistance and durability.

In order to improve the disadvantages of the sponge structure having a conventional symmetrical structure, the inventor of the present invention produced a hollow fiber membrane having the following structural features by the above-mentioned manufacturing method. 3 to 5, the figure is a scanning electron micrograph showing the hollow fiber membrane of the present invention, the hollow fiber membrane of the present invention has a finger structure (Fig. 9) or macropores (Fig. 6) of the prior art ) Is not formed, and the pore size increases from the outer surface to the inner surface, and in particular, the pore size of the outermost thin layer among the inner surface layers is 2 to 200 µm, and has a very large structural feature.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example

Examples 1 to 3

Example 1

A spinning solution was prepared by dissolving 20% by weight of polyisulfone (Mw: 30,000 to 70,000), 6.2% by weight of polyvinylpyrrolidone, 23.4% by weight of polyethylene glycol, 47.9% by weight of dimethyl acetamide, and 2.6% by weight of lithium chloride. . 90 wt% of dimethyl acetamide and 10 wt% of ultrapure water were stirred and dissolved to prepare an internal coagulation solution. The spinning stock solution and the internal coagulating solution were stirred at 100 rpm at 35 ° C. for 24 hours, and then degassed under vacuum of −1 kgf for 24 hours to remove bubbles. In the spinning condition, the temperature of the spinning stock solution was maintained at 35 ° C and the internal coagulating solution at 60 ° C. Spinning. The spun hollow fiber was continuously passed through a 2 cm air gap, and then passed through a coagulation bath and a washing bath containing 70 ° C. ultrapure water, and then wound up in a winder. At this time, the residence time of the coagulation bath was 20 seconds, and the residence time of the cleaning bath was 90 seconds. After spinning, the hollow fiber wound on the winder was cut to a length of 1 m and immersed in a water bath containing 60 ° C. ultrapure water for 24 hours, and then dried in an 80 ° C. hot air dryer for 24 hours.

Example 2

Except that 22% by weight of polyisulfone (BASF 6020), 6.2% by weight of polyvinylpyrrolidone, 23.4% by weight of polyethylene glycol, 46.3% by weight of dimethyl acetamide, and 2.1% by weight of lithium chloride were prepared. Prepared hollow fiber specimens in the same manner as in Example 1.

Example 3

A hollow fiber specimen was prepared in the same manner as in Example 2 except that the temperature of the coagulation bath was 50 ° C.

Comparative Examples 1 to 9

Comparative Example 1

A spinning solution was prepared by dissolving 16% by weight of polyisulfone (Mw: 30,000 to 70,000), 7.5% by weight of polyvinylpyrrolidone, 13.5% by weight of polyethylene glycol, 61.8% by weight of dimethyl acetamide, and 1.2% by weight of lithium chloride. Except that was prepared in the hollow fiber specimens in the same manner as in Example 2.

Comparative Example 2

A spinning stock solution was prepared by dissolving 13.7 wt% of polyisulfone (Mw: 30,000-70,000), 7.5 wt% of polyvinylpyrrolidone, 16.1 wt% of polyethylene glycol, 62.1 wt% of dimethyl acetamide, and 0.6 wt% of lithium chloride. Except that was prepared in the hollow fiber specimens in the same manner as in Example 2.

Comparative Example 3

22 wt% polyisulfone (Mw: 30,000-70,000), 16 wt% polyethylene glycol, 20 wt% tetrahydrofuran, 40 wt% N-methyl-2-pyrrolidine (NMP), 2 wt% lithium chloride Hollow fiber specimens were prepared in the same manner as in Example 2, except that the spinning solution was prepared by dissolving.

Comparative Example 4

Except that 22 wt% of polysulfone (Mw: 30,000 to 60,000), 16 wt% of polyethylene glycol, 20 wt% of tetrahydrofuran, 40 wt% of NMP, and 2 wt% of lithium chloride were used to prepare a spinning stock solution. Hollow fiber specimens were prepared in the same manner as in Example 2.

Comparative Example 5

16 wt% of polysulfone (Mw: 30,000 to 60,000), 7.5 wt% of polyvinylpyrrolidone, 13.5 wt% of polyethylene glycol, 61.8 wt% of dimethyl acetamide, and 1.2 wt% of lithium chloride were prepared to produce a spinning stock solution. Except for the hollow fiber specimens were prepared in the same manner as in Example 2.

Comparative Example 6

22% by weight of polyvinylidene fluoride (PVDF: 300,000-500,000), 7% by weight of polyvinylpyrrolidone, 24% by weight of polyethylene glycol, 3% by weight of cellulose acetate, 42% by weight of dimethyl acetamide, And hollow fiber specimens were prepared in the same manner as in Example 2 except that 2 wt% of lithium chloride was dissolved to prepare a spinning solution.

Comparative Example 7

Hollow fiber specimens were prepared in the same manner as in Example 2 except that the temperature of the coagulation bath was 25 ° C.

Comparative Example 8

Hollow fiber specimens were prepared in the same manner as in Example 2 except that the coagulation bath residence time was 10 seconds.

Comparative Example 9

Hollow fiber specimens were prepared in the same manner as in Example 2 except that the coagulation bath residence time was 5 seconds.

Property measurement method

Strength: Tensile tester Instron 5564 was used under the conditions of the initial sample length of 100 mm and the crosshead speed of 200 mm / min in an atmosphere of temperature 25 ℃, 50% relative humidity. Curved grips are used to minimize damage to the bite points.

Water permeability: Measure the amount of super pure water passed by applying a constant pressure to the unit area. At this time, ultrapure water was maintained at 25 ° C., and measured under an atmosphere of 25 ° C. and 50% relative humidity.

Permeability = water permeability (ℓ) / membrane area (m ² ) * pressure (kgf) * time (hr)

Average pore: The average pore was measured by PMI's non-mercury capillary pressure gauge CF-1000 Porometer (AEL, USA) by the half-dry method according to ASTM F316-03. Perfluoropolyester (brand name: Galwick) was used for the test solution.

Fractional performance (0.1 μm Bead removal rate): 0.1 μm diameter latex beads (Latex Beads) are diluted in 100 ppm of ultrapure water, permeated at a pressure of 1 kgf for a certain time, and the concentration of latex beads is measured to evaluate the fractional performance. .

Fractional Performance (%) = (1-Permeate Concentration / Stock Concentration) x 100

Table 1

TABLE 2

From the physical property measurement results, it can be seen that Examples 1 to 3 of the present invention have a strength of 800 gf / gf or more, and at the same time, a water permeability of 2,000 L / m ² * kgf * h or more. In general, as the content of polyisulfone increases, the strength increases, but the water permeability decreases due to a decrease in the space for forming pores. In Example 2 of the present invention, the same strength as in Example 1 is maintained while maintaining the strength of 850 gf / 本. It has a high water permeability of 2,000 LMH. This is a result obtained by lengthening the residence time in comparison with Comparative Examples 8 and 9 and making the coagulation bath temperature higher than Comparative Example 7. On the other hand, Comparative Examples 1 to 5, the composition of the spinning solution is out of the preferred content range of the present invention can be seen that the water permeability is lowered or the strength is significantly reduced, Comparative Example 6 is a polysulfone resin dash conventional as a base resin Polyvinylidene fluoride (PVDF: 300,000 to 500,000) used for the production of hollow fiber was applied, and the water permeability was remarkably reduced. In Comparative Examples 1 and 2, the content of the polysulfone-based resin was less than the preferred content range of the present invention, and the content of the organic solvent was more than the preferred content range of the present invention, indicating that the strength and the removal rate of 0.1 μm were lowered. have. This is because the polysulfone-based resin content is reduced and the content of the organic solvent is increased, the pore frequency in the hollow fiber is increased, the strength is lowered, and the average pore size is increased to 0.1 μm or more, so that the ability to remove spherical beads of 0.1 μm size is reduced.

In Comparative Examples 3 and 4, tetrahydrofuran (THF) was used instead of dimethyl acetamide (DMAc) as the organic solvent. This is because an organic solvent THF, which is more volatile than DMAc, uses an excessively fast phase conversion rate in which an organic solvent and a non-solvent are substituted, and thus the outer surface layer is densely formed because phase conversion is completed before pores are formed.

Comparative Example 7 can be seen that the water permeability and strength at the same time due to the low coagulation bath temperature, Comparative Examples 8 to 9 are poor pore formation due to poor pore formation because the residence time of the coagulation bath is short It can be seen that the transmittance is reduced.

Claims (15)

1. (A) 20 to 25% by weight of a polysulfone resin;

   (B) 40 to 50% by weight of the organic solvent; And

   (C) A polysulfone hollow fiber membrane containing 30 to 35% by weight of a hydrophilic additive, wherein the residence time exceeds 15 seconds in a coagulation bath in which the organic solvent (B) and the hydrophilic additive (C) are 50 to 70 ° C. It is an asymmetric sponge structure in which the phase transition with the medium forms pores, and the pore size is continuously increased from the outer surface layer to the inner surface layer, and the ratio of the pore size of the outer surface layer and the inner surface layer is from 1:10 to 1: 10000. Industrial polysulfone-based hollow fiber membrane, characterized in that the strength is more than 800 gf / 本, water permeability is 2,000 ℓ / m ² * kgf * h or more.
2. The method of claim 1, wherein the organic solvent (B) is dimethyl acetamide (dimethylacetamide, DMAc), dimethyl formamide (DMF), chloroform (chloroform), N-methyl-2-pyrrolidone (N-Methyl-2- Pyrrolidone), dimethyl sulfoxide (Dimethylsulfoxide), and an industrial polysulfone-based hollow fiber membrane, characterized in that selected from the group consisting of.
3. The method according to claim 1, wherein the hydrophilic additive (C) is polyvinylpyrrolidone, polyethylene glycol, ethylene glycol, methyl alcohol, glycerin, cellulose acetate, polyvinyl alcohol, sodium chloride, lithium chloride, polypropylene glycol, castor oil, Zinc chloride, and mixtures thereof. Industrial polysulfone-based hollow fiber membranes.
4. The industrial polysulfone-based hollow fiber membrane according to any one of claims 1 and 3 to 4, wherein the polysulfone-based resin (A) is polysulfone or polyisulfone.
5. Preparing a spinning solution containing 20 to 25 wt% of a polysulfone resin (A), 40 to 50 wt% of an organic solvent (B), and 30 to 35 wt% of a hydrophilic additive (C); Preparing an internal coagulating solution; Spinning the spinning stock solution and the internal coagulating solution through a double nozzle; Forming organic pores by phase-conversion with the nonsolvent in the coagulation bath and the cleaning bath by the organic solvent (B) and the hydrophilic additive (C); And a winding step, wherein the total residence time in the coagulation bath and the washing bath is greater than 90 seconds, the residence time in the coagulation bath is more than 15 seconds, and the coagulation bath temperature is 50 to 70 ° C. Method for producing an industrial polysulfone hollow fiber membrane.
6. The method of claim 6, wherein the temperature of the spinning stock solution is 30 to 40 ℃, the temperature of the internal coagulating solution is 50 to 70 ℃ manufacturing method of the industrial polysulfone-based hollow fiber membrane.
7. The method of claim 6, wherein the polysulfone resin (A) is a polysulfone or a polysulfone.
8. The method of claim 6, wherein the organic solvent (B) is dimethyl acetamide (dimethylacetamide, DMAc), dimethyl formamide (DMF), chloroform (chloroform), N-methyl-2-pyrrolidone (N-Methyl-2- Pyrrolidone), dimethyl sulfoxide (Dimethylsulfoxide), and a method for producing an industrial polysulfone hollow fiber membrane, characterized in that selected from the group consisting of.
9. The method according to claim 6, wherein the hydrophilic additive (C) is polyvinylpyrrolidone, polyethylene glycol, ethylene glycol, methyl alcohol, glycerin, cellulose acetate, polyvinyl alcohol, sodium chloride, lithium chloride, polypropylene glycol, castor oil, Zinc chloride, and mixtures thereof. The method for producing an industrial polysulfone-based hollow fiber membrane.
10. The method of claim 6, wherein the spinning stock solution is prepared by dissolving the spinning stock solution at a compounding temperature of 20 to 40 ° C. and a stirring speed of 80 to 120 rpm for 12 to 24 hours, followed by 12 to 24 hours under a vacuum pressure of −5 to 1 kgf. Method for producing an industrial polysulfone hollow fiber membrane further comprises the step of defoaming to remove bubbles in the spinning stock solution (DOPE).
11. The method of claim 6, wherein the internal coagulating solution preparation step is a solvent in dimethyl acetamide (DMAc), dimethyl formamide (DMF), chloroform (N-methyl-2-pyrrolidone) N-Methyl-2-Pyrrolidone), Dimethylsulfoxide (Dimethylsulfoxide) A method for producing an industrial polysulfone hollow fiber membrane, characterized in that it is blended with at least one selected from the group consisting of.
12. The method of claim 6, wherein the non-solvent is 5 to 25% by weight, and the organic solvent is 75 to 95% by weight.
13. The method of claim 14 or 15, wherein the mixing temperature of the internal coagulation solution is 50 to 70 ℃, the stirring speed is mixed for 12 to 24 hours at 80 to 120 rpm, and then 6 to under a vacuum of -5 to -1 kgf A method for producing an industrial polysulfone hollow fiber membrane, characterized in that the air bubbles are degassed for 12 hours to remove bubbles from the internal coagulation solution.
14. The spinning apparatus used in the spinning step and the step of forming pores is a spinning raw liquid (Dope) and internal coagulating liquid (Core) manufacturing tank, nozzle, nozzle holder, primary coagulation tank, washing tank, winding Method for producing an industrial polysulfone hollow fiber membrane, characterized in that consisting of a washing tank for removing the residual solvent of the sample (sample) after the completion of the blowing and spinning.
15. 18. The method according to claim 17, wherein the cleaning bath temperature is 50 to 70 ° C.

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