KR20030086741A - Composition for producing polyethersulfone membrane and method for preparing microfilteration membrane using the same - Google Patents

Abstract

PURPOSE: Provided is a composition for preparing a microporous polyether sulfone membrane, which has uniform pore sizes and high permeability and is applied to water treatments and micro-filtering. CONSTITUTION: The composition comprises 10-30 wt% of polyether sulfone and 1-58 wt% of methyl cellosolve and the balance amount of N-methyl-2-pyrrolidone or N,N-dimethylformamide as a solvent. The microporous polyether sulfone membrane is produced by the method comprising the steps of: (a) forming a polymer solution of the composition; (b) applying the polymer solution to a support; (c) contacting it to air under a predetermined temperature and humidity to induce the phase separation of the surface coated with the polymer solution and to form micropores on the membrane surface; (d) dipping the membrane into water as a non-solvent solution in a non-solvent bath to perform the gelling of the surface coated with the polymer solution; and (e) washing the gelled surface and drying in the air to remove the remaining solvent, additives and water.

Description

COMPOSITION FOR PRODUCING POLYETHERSULFONE MEMBRANE AND METHOD FOR PREPARING MICROFILTERATION MEMBRANE USING THE SAME}

The present invention relates to a composition for preparing microporous polyethersulfone membrane for microfiltration and a method for producing microporous polyethersulfone membrane for microfiltration using the same.

Microporous membranes are widely used in various fields such as battery separators, electrolyte capacitor separators, various filters, wet permeable and waterproof garments, reverse osmosis membranes, ultrafiltration membranes or microfiltration membranes.

The microporous membrane in the membrane is economically and technically very important in the material separation process. In various membrane separation processes, membranes used today have various structures and functions and are produced by various production methods. Among them, research on water treatment membranes started a long time ago, but in 1963, Professor Reid suggested that membranes could be used for desalination of seawater, and Loeb in 1963. After Surairajan (Sourirajan) succeeded in producing an asymmetric membrane through a phase-transfer process based on the cellulose acetate material, a study on a full-fledged separation membrane for water treatment was made. The phase transition process is a nonsolvent induced phase inversion (NIPI) process, in which a polymer is dissolved in a suitable solvent to form a polymer solution, and then a thin film is cast and deposited on the non-solvent to obtain a solid film. . At the time of publication, this was a rather breakthrough method for making membranes, not a common one, and permeation performance has also made significant progress. The process by casting, presented in 1985, demonstrates that the underlying mechanisms and governing factors in the structural aspects of the two membrane types, finger and sponge, are identical. The membrane of this type has an asymmetric structure and consists of a porous support layer and a dense skin layer effective for solute separation. Membranes prepared in this way are used in a wide range of membrane production methods, from microfiltration to gas permeation. Most polymer membranes are usually made by a phase-transfer process regardless of their structure and mass transfer properties. The polymer membrane is typically prepared by selecting a suitable polymer solvent to make a polymer solution, casting it to form a thin sheet, and depositing it in a solid phase. Such deposited polymer films are generally formed in contact with air for a short time and in contact with the nonsolvent liquid in the precipitation bath. At this time, in order to increase the porosity of the membrane, it is common that a specific ratio of a specific nonsolvent is contained in the casting solution. As such, the non-solvent casting solution is referred to as an unstable casting solution. Since the pore characteristics of the membrane surface vary depending on the type and content of the non-solvent contained in the casting solution, this is an important factor in determining the membrane shape.

As the material of the membrane produced by this method, US Patent Nos. 3,133,132 and 3,133,137 disclose a cellulose acetate system. Membranes made of cellulose-based materials are excellent in performance and to some extent resistant to acids and alkalis, but have disadvantages such as degradation by bacteria and problems in storage. To overcome these shortcomings, many existing researchers have attempted to co-polymerize and blend polymers, introduce polar or hydrophilic groups to reinforce the chemical properties of the membrane, or modify the physical structure by changes in film forming conditions, stretching and crystallinity. Attempts have been made to increase the permeation characteristics of the membrane.

Based on these studies, in order to improve the permeation characteristics of the membrane, the development of a thinning technique that minimizes the thickness of the dense layer of the skin substantially acting on the separation characteristics has been proposed. As a result, a membrane having excellent performance was developed by selecting a porous support that maintains mechanical strength but does not affect its inherent permeation characteristics, and casts it into a thin film. As a membrane produced using this method, there is a polyamide-based composite membrane prepared according to US Patent No. 3,951,815, which is to compensate for the disadvantages of the existing membrane and excellent permeability. This manufacturing method, when compared with the membrane having asymmetric structure of a single material prepared by the phase-transfer process, it is possible to select a membrane material having a support and separation selectivity not only improve the permeation characteristics, but also the support and the membrane material Through the selection of physical and chemical properties can be improved.

Currently known methods for producing polymer thin films include preparing a polymer solution and attaching it to a support, such as separate casting and lamination, dip-coating, and Langmuir-Brodget. have. In addition, there are various methods of the In-Situ method, and are currently commercialized by various membrane material development and performance improvement in the field of reverse osmosis and gas separation. Examples include FT, NF-series from Film Tech, NS-series from NSRI, and PA-series from UOP.

Most of the existing researches related to reverse osmosis membrane development have been focused mainly on desalination of seawater, and thus require high desalination and high pressure operating conditions. However, such reverse osmosis membranes are not suitable for applications in other fields, such as wastewater treatment requiring high chemical resistance properties, purification of organic solvents, and separation of high concentrations.

Polyethersulfone is a polymer used for the production of membranes having high chemical resistance and resistance to microorganisms, and various methods of preparing microporous membranes using polyethersulfone are disclosed in US Pat. Nos. 5,886,059 and 5,869,174. , 5,444,097, 4,976,859, 4,968,733 and the like. However, at present, there is almost no membrane produced using polyether sulfone in Korea. Polyethersulfone is used to prepare membranes such as nonporous, porous, asymmetrical, or symmetrical, and has various applications such as ultrafiltration, reverse osmosis, microfiltration, and the like. Polyethersulfone exhibits high resonance stability due to the coupling of phenyl rings linked to sulfone groups, and the sulfone groups serve to block the activity of aromatic electrons and exhibit heat resistance and oxidation resistance. The two stability achieved by the resonance effect increases the bond strength and flat atomic arrangement, which contributes to the stiffening of the material at higher temperatures. In addition, it is known that mechanical strength is relatively superior to polysulfone, and more stable in continuous use. Accordingly, the conventional methods for preparing membranes are prepared by dissolving and casting a mixture containing polyethersulfone and additives in a solvent, followed by a phase transition through heat treatment from a polymer sheet or a phase shift through a nonsolvent process using mainly water. Reported is a method for producing a microporous membrane by extracting and additives.

Among these methods, Wang et al. In US Pat. No. 5,886,059 proposes the preparation of a membrane that is prepared according to the phase separation mechanism in the unstable region of the polymer solution and is well evaluated in pore size control. However, it is very difficult to deal with polymer solutions in industrial membrane production processes, and the polymer solutions presented by these polymers exhibit disadvantages in membrane production processes because of their very low viscosity. Through such a process, it is difficult to find conditions for obtaining pores showing a uniform distribution in manufacturing a large-scale separator sheet, and there are many difficulties in controlling permeability to a desired level.

Therefore, there is a strong demand for providing a microporous membrane having various permeation characteristics and applicable to various fields. In addition, even if applied to the same field, there is a need to provide a microporous membrane having a low selectivity and varying permeability while having a constant selectivity in improving membrane properties.

Therefore, the present invention, using the basic physical and chemical properties of the polyether sulfone, in order to solve the conventional problems as described above, and the composition used to efficiently prepare a microporous membrane having a constant pore size and high permeability; It is an object to provide a method for producing a microporous membrane using the same.

Figure 1 shows an electron micrograph of the film obtained according to a preferred example of the present invention, 1a and 1b are electron micrographs of the film prepared according to the conditions of Examples 1 and 2, respectively.

Figure 2 shows an electron micrograph of the film obtained according to a preferred example of the present invention, 2a and 2b are electron micrographs of the films prepared according to the conditions of Example 3 and Example 4, respectively.

3 shows electron micrographs of the membranes obtained according to a preferred example of the present invention, wherein 3a, 3b and 3c are electron micrographs of the membranes prepared according to the conditions of Examples 8, 9 and 10, respectively.

4 shows an electron micrograph of a film obtained according to a preferred embodiment of the present invention. Prepared according to the conditions of Example 11.

Fig. 5 shows the pore distribution of the average pore size of the membrane obtained according to a preferred example of the present invention and is a representative pore distribution diagram of the membranes obtained in Examples 8, 9 and 10.

The present invention relates to a composition for producing a polyether sulfone membrane and a method for producing a microporous polyether sulfone membrane for microfiltration using the same.

First, the present invention provides a composition for preparing a microporous polyethersulfone membrane for microfiltration, including a solvent, a polyethersulfone as a polymer, and methyl cellosolve (MCS) as an additive. The composition may further contain a water-soluble polymer polyethylene glycol or glycerol.

The composition for preparing microporous polyether sulfone membrane for microfiltration is based on the total mass of the polymer solution, 10 to 30% by weight of polyether sulfone as a polymer, well mixed with a solvent, but acts as a non-solvent to the polymer. Methyl cellosolve (MCS) 1 to 58% by weight and excess amount of the solvent. At this time, the composition further comprises 0 to 30% by weight of polyethylene glycol or 0 to 13% by weight of glycerol based on the total mass of the final polymer solution for the production of a membrane having a more uniform pore distribution and less contamination. can do. The composition may contain N-methyl-2-pyrrolidone (NMP) or N, N-dimethylformamide (DMF) as a solvent, and the molecular weight of polyethylene glycol used as an optional component is in the range of 1,000 to 35,000. desirable.

In addition, the present invention

(1) preparing a polymer solution by dissolving Methyl Cellosolve (MCS) as a non-solvent additive to the polymer polyethersulfone and the solvent but mixing well with the solvent,

(2) applying the polymer solution to a support,

(3) inducing phase separation of the surface coated with the polymer solution by contacting air containing a constant humidity at a constant temperature to form fine pores on the surface of the membrane,

(4) gelling the surface coated with the polymer solution through a nonsolvent deposition process at a predetermined temperature, and

(5) It provides a method for producing a fine ether polyether sulfone membrane comprising the step of washing the gelled surface and drying in air at a predetermined temperature to remove the remaining solvent and additives.

In step (1), polymer polyethersulfone, based on the total weight of the polymer solution, using N-methyl-2-pyrrolidone (NMP) or N, N-dimethylformamide (DMF) as a solvent 10 to 30% by weight, the polymer is mixed well with the solvent, but the polymer is prepared by mixing a solvent corresponding to 1 to 58% by weight of methyl cellosolve (MCS) and an extra amount to the polymer polyether sulfone. . At this time, the polymer solution, based on the total mass of the final polymer solution, 0 to 30% by weight of polyethylene glycol or 0 to 13% by weight of glycerol may be additionally added to prepare a polymer solution. The polymer solution is prepared by dissolving at room temperature in contact with air, and when polyethylene glycol is added, the polymer solution is preferably prepared at 40 to 75 ° C. to prepare a stable polymer solution.

In the step (2), the polymer solution is applied to the support to a certain thickness. In the embodiment of the present invention, a support made of polyester and PET is used as the support, but those generally used as a support for film production may be used, and those having appropriate porosity or surface roughness may be selected according to the purpose of use. Can be used. At this time, the thickness to be applied is preferably in the range of 80 to 250 μm, and if the thickness is applied thicker or thinner, there is a possibility that the performance of the film may be reduced. In order to apply a film having a predetermined thickness, for example, a casting knife having a predetermined range of knife spacings can be used, and in addition, it is conventional, such as roll coating or one side dip-coating, or the like. The method used can be used. At this time, the coating process is slightly different depending on the components of the polymer solution, but is carried out in the range of -10 ~ 100 ℃, more preferably in the room temperature to 100 ℃ range.

In step (3), it is preferable to form pores on the surface of the membrane by exposing the support on which the polymer solution is applied to air at a temperature of 20 to 100 ° C. and a relative humidity of 70 to 100% for 0 to 3 minutes.

Further, in step (4), the non-solvent deposition process is preferably performed at a temperature in the range of about 25 ~ 80 ℃. When performing a nonsolvent deposition process in nonsolvent, it is common to use water as a nonsolvent. In this case, only water may be used, and a small amount of N, N-dimethylformamide (DMF) may be additionally added thereto. At this time, it is preferable to add N, N-dimethylformamide (DMF) at 5% by weight or less of the total amount of the nonsolvent solution. That is, the nonsolvent deposition process is based on the total amount of the solution in the nonsolvent, non-solvent addition of 100 to 95% by weight of non-solvent, such as water and 0 to 5% by weight of N, N-dimethylformamide (DMF) This can be done at In the non-solvent deposition process, when DMF is added to the non-solvent as described above, the solvent and the additives are extracted from the polymer solution applied during the film formation (gelation process), and the mechanism by which the non-solvent penetrates into the applied polymer solution. This change results in a change in the properties of the membrane, and it is possible to produce a membrane having more excellent performance by changing the difference in the mutual diffusion rate between the nonsolvent and the solvent in terms of the polymer.

By performing steps (3) and (4) above, fine pores having a diameter of 0.01 to 1 µm, preferably less than 0.5 µm, more preferably less than 0.3 µm, are formed on the surface of the support membrane, It can be gelled.

In the step (5), washing of the gelled porous membrane surface can be performed using acetone, methanol, ethanol or water, and it is particularly preferable to use water of about 50 to 85 ℃. After washing, it is dried in air, preferably at a temperature of 70 to 100 ° C., finally producing a microporous polyethersulfone membrane.

Methyl cellosolve (MCS) used in the present invention was conventionally used, but its amount is about 60% by weight or more relative to the polymer solution, and as a result, a membrane having a pore size of 0.08 to 1 μm was produced. However, the present invention provides a method of significantly reducing the amount of methyl cellosolve to 1 to 58 parts by weight and forming finer pores of 0.01 to 1 μm by controlling relative humidity or adding polyethylene glycol.

The surface coated with the polymer solution through the method according to the present invention becomes an initial state of the pore-forming process by the nucleus-growth mechanism when the surface becomes unstable. At this time, the film applied through the non-solvent deposition process is a phase change in a very short time, and finally a porous film is formed.

Porous polymer membrane prepared in the present invention is a polyether sulfone membrane, characterized in that the pore size is 0.01 ~ 1 ㎛ and the pure permeate flow rate is 500 to 1400 LMH, as shown in Table 1, 2, 3 and Figure 5 graph, Due to such excellent porosity, the membrane is excellent in permeation performance and can be applied to precision filtration and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example

Example 1

14.4 wt.% (200 g) of polyethersulfone (Ultrason E 6020P, BASF) and 42.8 wt.% (600 g) of N-methyl-2-pyrrolidone (NMP) used as solvent, based on the total weight of the polymer solution 42.8 wt% (600 g) of cellosolve (MCS, KANTO) was dissolved at room temperature under conditions not in contact with air to prepare a stable and uniform polymer solution. The polymer solution was then heated to 40 ° C. and the polymer solution at 40 ° C. was cast on a polyester nonwoven fabric using a casting knife with a knife spacing of 154 μm. Immediately after casting, the deposition process was carried out in a nonsolvent containing water as a nonsolvent at 40 ° C. for 3 seconds in a humidity controller with humidity maintained at 90% or higher. Then, the membrane prepared with about 70 water was washed and then dried in air at 80 ° C. to remove residual solvent, additives and water, and finally a membrane was obtained.

An electron micrograph of the surface of the film thus obtained is shown in Fig. 1A. At this time, in order to measure the pore shape of the lower part, the pore size and distribution of the resulting membrane were used using an Auto Perm-Porometer (CFP-1200AEL, PMI) using the Bubble Point Method. It was measured by. The maximum pore size was 0.30 μm and the water bubble point (WBP) was 22.02 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. These measurement results are shown in Table 1.

Example 2

The polymer solution having the same composition as in Example 1 was prepared by dissolving at room temperature under a condition not in contact with air, and then heated to 40 ° C., and the polymer solution at 40 ° C. was prepared using a casting knife having a knife spacing of 154 μm. Cast to ester nonwoven. Immediately after casting, exposure to 100 ° C. conditions for 8 seconds in a humidity controller where the humidity was maintained above 90% and the deposition process was carried out in water in a non-solvent at 40 ° C. Other processes were the same as Example 1, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 1B. As can be seen in Figure 1b, the formed film exhibited a nodular form.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.166 μm and WBP was 22.25 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 1.

Example 3

The polymer solution having the same composition as in Example 1 was prepared by dissolving at room temperature under a condition not in contact with air, and then heated to 40 ° C., and the polymer solution at 40 ° C. was prepared using a casting knife having a knife spacing of 154 μm. Cast to ester nonwoven. Immediately after casting, the humidity controller was kept at 60 ° C. for 5 seconds in a humidity controller maintained at 90% or higher, and the deposition process was performed in water in a non-solvent at 40 ° C. Other processes were the same as Example 1, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 2A.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.173 μm and WBP was 22.19 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 1.

Example 4

The polymer solution having the same composition as in Example 1 was prepared by dissolving at room temperature under a condition not in contact with air, and then heated to 40 ° C., and the polymer solution at 40 ° C. was prepared using a casting knife having a knife spacing of 154 μm. Cast to ester nonwoven. Immediately after casting, the humidity controller was kept at 60 ° C. for 10 seconds in a humidity controller maintained at 90% or higher, and the deposition process was performed in water in a non-solvent at 40 ° C. Other processes were the same as Example 1, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 2B.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum pore size was 0.382 μm and WBP was 9.38 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 1.

Example 5

The polymer solution prepared by adding 30 g (4.5 wt% of glycerol) to the polymer solution of the composition prepared in Example 1 was prepared by dissolving at room temperature under conditions not in contact with air, and then heated to 40. The polymer solution of 40 was cast on a polyester nonwoven fabric using a casting knife of 154 μm. Immediately after casting, they were exposed to 60 ° C. conditions for 5 seconds in a humidity controller where the humidity was maintained at 90% or higher, and the deposition process was performed in water in a non-solvent at 60 ° C. Other processes were the same as Example 1, and the film | membrane was manufactured.

Pore size and distribution were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.177 μm and WBP was 18.93 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 1.

Example 6

14.2 wt% (200 g) polyethersulfone (Ultrason E 6020P, BASF) in 42.5 wt% (600 g) N-methyl-2-pyrrolidone (NMP) used as solvent, based on the total weight of the polymer solution 41.1 wt% (580 g) of Cellosolve (MCS, KANTO) and 2.2 wt% (30 g) of glycerol were dissolved at room temperature under no contact with air to prepare a stable and uniform polymer solution. The heated polymer solution was then cast to a polyester nonwoven using a casting knife with heating to 40 ° C. and a knife spacing of 154 μm. Immediately after casting, exposure to 60 ° C. conditions was performed for 5 seconds in a humidity controller with humidity controlled to 90% or higher, and the deposition process was performed in water in a non-solvent at 60 ° C. Other processes were carried out in the same manner as in Example 1 to prepare a membrane.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.24 μm and the WBP was determined to be 11.71 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. These measurement results are shown in Table 1.

Example 7

14.8 wt% (200 g) polyethersulfone (Ultrason E 6020P, BASF) in 44.4 wt% (600 g) N-methyl-2-pyrrolidone (NMP) used as solvent, based on the total weight of the polymer solution 38.5 wt% (520 g) of Rosolve (MCS, KANTO) and 2.3 wt% (30 g) of glycerol were dissolved at room temperature under no contact with air to prepare a stable and uniform polymer solution. The heated polymer solution was then cast to a polyester nonwoven using a casting knife with heating to 40 ° C. and a knife spacing of 154 μm. Immediately after casting, exposure to 60 ° C. conditions was performed for 120 seconds in a humidity controller with humidity controlled to 90%, and the deposition process was performed in water in a non-solvent at 60 ° C. Other processes were carried out in the same manner as in Example 1 to prepare a membrane.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.144 μm and the WBP was determined to be 9.39 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. These measurement results are shown in Table 1.

As can be seen from Table 1, the maximum distribution pore size of the membrane prepared through each embodiment is in the range of about 0.15 ~ 0.4 ㎛, and excellent permeation flow rate compared to the conventional membrane used in conventional microfiltration. In particular, the membrane prepared according to Example 3 has an excellent performance in removing powder of 0.2 μm or more with an average pore size of 0.173 μm and has high permeability. As for the distribution of pores, it was confirmed that the pores of about 0.3 μm were very narrowly distributed in Example 1, and in the following case, the maximum pore size was somewhat large. However, the distribution frequency is very small and does not significantly affect the performance of the membrane. The contaminant removal ability and permeability in the membrane performance of the conventional commercial membrane are somewhat higher in contamination and lower in permeability than the membrane produced by the present invention. In particular, in the surface contamination, it was evaluated that the reproducibility of the membrane state was excellent in the case of the present invention, and that the performance of the permeability during regeneration was superior to that of the commercial membrane.

TABLE 1

Bubble Point Pressure (PSI) Bubble point pore size (microns) Maximum distribution pore size (microns) Permeate Flow Rate (LMH) Fig. No. Example 1 22.02 0.302 0.300 1200 1a Example 2 22.25 0.298 0.166 950 1b Example 3 22.19 0.299 0.173 1100 2a Example 4 9.38 0.710 0.382 660 2b Example 5 18.93 0.357 0.177 500 - Example 6 11.71 0.566 0.240 640 - Example 7 10.23 0.649 0.144 750 -

Example 8

36.4 weight% (600 g) N-methyl-2-pyrrolidone (NMP) used as a solvent based on the total weight of the polymer solution, 12.3 weight% (200 g) polyethersulfone (Ultrason E 6020P, BASF) and Methyl cellosolve (MCS, KANTO) 51.3% by weight (850g) was dissolved at room temperature under the condition of not in contact with air to prepare a stable and uniform polymer solution. Then, the heated polymer solution was cast on a PET nonwoven fabric using a casting knife with heating to 55 ° C. and a knife spacing of 180 μm. Immediately after casting, exposure to 50 ° C. conditions was performed for 15 seconds in a humidity controller with humidity controlled at 90% or higher, and the deposition process was carried out in water in a 48 ° C. nonsolvent. Then, after being left for about 10 minutes, the resulting membrane was washed with water at about 80 ° C., dried in air at 80 ° C. to remove residual solvent and water, and finally a membrane was prepared.

An electron micrograph of the film surface thus prepared is shown in FIG. 3A. In order to measure the pore morphology of the lower part, the pore size and distribution of the membrane were measured using an autofirm-porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.131 μm and the WBP was determined to be 35.51 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. These measurement results are shown in Table 2.

Example 9

Prepared by dissolving the polymer solution of the same composition as in Example 8 at room temperature under the condition of not in contact with air, and then heated to 30 ℃, using a casting knife with a knife interval of 180 ㎛ PET PET solution of the 30 ℃ Cast to nonwoven. Immediately after casting, exposure to 60 ° C. conditions for 20 seconds in a humidity controller with humidity controlled at 90% or higher and a non-solvent deposition process at 48 ° C. was performed. Other processes were the same as Example 8, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 3B. Through 3b, it was confirmed that the formation of the nadula-type film is in progress.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.143 μm and WBP was 28.95 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 2.

Example 10

The polymer solution having the same composition as in Example 8 was prepared by dissolving at room temperature under a condition not in contact with air, and then heated to 30 ° C., using a casting knife having a knife spacing of 170 μm and maintaining 50 ° C., at 30 ° C. The polymer solution of was cast on a PET nonwoven fabric. Immediately after casting, a humidity controller with humidity controlled at 90% or higher was exposed to 60 ° C. conditions for 25 seconds and a nonsolvent deposition process was run at 48 ° C. Other processes were the same as Example 8, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 3C. It can be seen from Figure 3c that the pores of the typical nadula form were formed.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.169 μm and WBP was 32.16 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 2.

Example 11

The polymer solution having the same composition as in Example 1 was prepared by dissolving at room temperature under conditions not in contact with air, and then heated to 40 ° C., and the polymer solution at 40 ° C. was prepared using a casting knife having a knife spacing of 154 μm. Cast to nonwoven. Immediately after casting, the humidity controller was exposed to 20 ° C. conditions for 20 seconds in a humidity controller with a humidity of 90% or higher, and a deposition process was performed in water in a non-solvent of 40 ° C. Other processes were the same as Example 1, and the film | membrane was manufactured. An electron micrograph of the film surface thus formed is shown in FIG. 4.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. Maximum pore size was 0.217 μm and WBP was 9.16 psig. The average value of the pure water permeability of each sample was measured using the round porous plate (about 12.5 cm <2>) of diameter 40mm in 500 mmHg vacuum conditions. These measurement results are shown in Table 2.

The results in Table 2 show that the distribution of pores is more narrow in the case of the membranes according to Examples 8, 9 and 10. As shown in FIG. 3, the membranes produced by Examples 8, 9, and 10 showed more excellent surface properties, which significantly reduced contamination in the pollutant permeability test, and also showed a remarkable increase in regeneration.

TABLE 2

Bubble Point Pressure (PSI) Bubble point pore size (microns) Maximum distribution pore size (microns) Permeate Flow Rate (LMH) Fig. No. Example 8 36.51 0.182 0.131 510 3a Example 9 28.95 0.231 0.143 590 3b Example 10 32.16 0.208 0.169 670 3c Example 11 9.16 0.776 0.217 1130 4

Example 12

16.6 weight% (200 g) polyethersulfone (Ultrason E 6020P, BASF) to 50 weight% (600 g) of N, N-dimethylformamide (DMF, BASF) used as solvent, based on the total weight of the polymer solution Cellosolve (MCS, KANTO) 25% by weight (300g) and polyethylene glycol (PEG) 8.4% by weight (100g) was dissolved at room temperature under a condition not in contact with air to prepare a stable and uniform polymer solution. Then, the heated polymer solution was cast to a PET nonwoven fabric using a casting knife having a heating to 30 ° C. and a knife spacing of 175 μm. Immediately after casting, they were exposed to 50 ° C. conditions for 20 seconds in a humidity controller with a humidity of 90% or higher and the deposition process was performed in a non-solvent solution consisting of 97% by weight water and 3% by weight DMF in a 55 ° C. nonsolvent. Was executed. Other processes were carried out in the same manner as in Example 1 to prepare a membrane.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.684 μm and the WBP was determined to be 9.52 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. The measurement results are shown in Table 3.

Example 13

12.5 wt% (200 g) polyethersulfone (Ultrason E 6020P, BASF) in 37.5 wt% (600 g) N-methyl-2-pyrrolidone (NMP) used as solvent, based on the total weight of the polymer solution 37.5 wt% (600 g) of Rosolve (MCS) and 12.5 wt% (200 g) of polyethylene glycol (PEG) were dissolved at room temperature under a condition not in contact with air to prepare a stable and uniform polymer solution. The heated polymer solution was then cast to a PET nonwoven fabric using a casting knife, heated to 40 ° C. and having a knife spacing of 155 μm. Immediately after casting, they were exposed to 56 ° C. conditions for 25 seconds in a humidity controller with humidity controlled above 90%, and the deposition process was performed in a non-solvent solution consisting of 95.5% by weight of water and 4.5% by weight of DMF in a 56 ° C. nonsolvent. Was performed. Other processes were carried out in the same manner as in Example 1 to prepare a membrane.

The pore size and distribution of the resulting membrane were measured using an Auto Firm-Porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.868 μm and the WBP was determined to be 7.898 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. The measurement results are shown in Table 3.

Example 14

14.8 wt% (200 g) polyethersulfone (Ultrason E 6020P, BASF) in 44.4 wt% (600 g) N-methyl-2-pyrrolidone (NMP) used as solvent, based on the total weight of the polymer solution 29.6 wt% (400 g) of Rhosolve (MCS) and 11.2 wt% (150 g) of polyethylene glycol (PEG) were dissolved at room temperature under a condition not in contact with air to prepare a stable and uniform polymer solution. The heated polymer solution was then cast to a polyester nonwoven using a casting knife with heating to 30 ° C. and a knife spacing of 155 μm. Immediately after casting, exposed to 52 ° C. conditions for 25 seconds in a humidity controller with a humidity of 90% and performing a deposition process in a non-solvent solution consisting of 95.5% by weight of water and 4.5% by weight of DMF in a 52 ° C. nonsolvent. It was. Other processes were carried out in the same manner as in Example 1 to prepare a membrane.

The pore size and distribution of the resulting membrane were measured using an autofirm porometer (CFP-1200AEL, PMI) using the bubble point method. The maximum distributed pore size was 0.26 μm and the WBP was determined to be 12.4 psig. Moreover, the average value of the pure permeability of each sample was measured on 500 mmHg vacuum conditions using the circular porous plate (about 12.5 cm <2>) of diameter 40mm. The measurement results are shown in Table 3.

Table 3 shows the results obtained by using additional additives.

TABLE 3

Bubble Point Pressure (PSI) Bubble point pore size (microns) Microns at maximum pore size distribution Permeate Flow Rate (LMH) Fig. No. Example 12 9.52 0.69 0.684 1430 - Example 13 7.898 0.87 0.87 710 - Example 14 12.47 0.54 0.26 730 -

As described above, the present invention is to solve the problems and limitations of the method for producing a microporous membrane for microfiltration through the conventional non-solvent induced phase transition method, the pore size is 1 ㎛ using the composition and method of the present invention Microporous membranes having a small pore distribution of less than, preferably less than 0.5 μm, more preferably less than 0.3 μm can be readily prepared. Membranes prepared as described above can be widely used in various fields such as various filters, wet permeable reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, and the like.

Claims (13)

N-methyl-2-pyrrolidone (NMP) or N, N-dimethylformamide (DMF) as a solvent, 10 to 30% by weight of polyethersulfone, 1 to 58, based on the total weight of the composition A composition for preparing a microporous polyether sulfone membrane for microfiltration comprising a weight percent methyl cellosolve (MCS) and the solvent corresponding to the excess amount. The composition of claim 1, further comprising 0 to 30% by weight of polyethylene glycol or 0 to 13% by weight of glycerol based on the total weight of the final composition. The composition of claim 2, wherein the polyethylene glycol has a molecular weight in the range of 1,000 to 35,000. (1) 10 to 30% by weight of polyethersulfone, based on the total weight of the polymer solution, using N-methyl-2-pyrrolidone (NMP) or N, N-dimethylformamide (DMF) as a solvent Preparing a polymer solution by mixing 1 to 58% by weight of methyl cellosolve (MCS) and the solvent corresponding to the excess amount, (2) applying the polymer solution to a support, (3) inducing phase separation of the surface coated with the polymer solution by contacting with air containing a predetermined humidity at a predetermined temperature to form fine pores on the membrane surface, (4) performing a deposition process in the nonsolvent using water as the nonsolvent solution to gel the surface coated with the polymer solution, and (5) washing the gelled surface and drying in air to remove residual solvents, additives and water. The method according to claim 4, wherein in the preparation of the polymer solution of step (1), 0-30 wt% polyethylene glycol or 0-13 wt% glycerol is additionally added and mixed based on the total weight of the final polymer solution. Thereby to produce a polymer solution. The method of claim 4, wherein step (2) is carried out at a temperature range of -10 to 100 ℃. The method of claim 4, wherein the step (2) is performed by applying the polymer solution to a support having a thickness of 80 to 250 µm. 8. The method of claim 7, wherein the step (2) is performed using a casting knife having a knife spacing in a desired thickness range, or using a roll coating or one side dip-coating method. The method is carried out by applying a polymer solution to a support. 5. The method according to claim 4, wherein the step (3) is performed by exposing to air for 0 to 3 minutes at a temperature of 20 to 100 ° C and a relative humidity of 70 to 100%. The non-solvent solution of claim 4, wherein the step (4) is performed based on the total weight of the non-solvent, the non-solvent solution containing not less than 95% by weight of water and not more than 5% by weight of N, N-dimethylformamide (DMF). How to do it using. The fish of claims 1 to 3 is prepared using the composition according to claim 1, or is prepared by the method according to claim 4, having a pore size of 0.01 to 1 μm and a pure permeate flow rate. Microporous polyethersulfone membrane for microfiltration, which is 500-1400 LMH. 12. The microporous polyethersulfone membrane for microfiltration of claim 11, wherein the pore size is less than 0.5 μm. 12. The microporous polyethersulfone membrane for microfiltration of claim 11, wherein the pore size is less than 0.3 μm.