KR20060100748A - Method of preparing polyethersulfone membrane using vapor induced phase inversion and nonsolvent induced phase inversion - Google Patents

Abstract

The present invention comprises the steps of (1) preparing a polymer solution by mixing a polymer polyether sulfone, a solvent, a first pore-forming agent and a second pore-forming agent; (2) casting the polymer solution; (3) exposing the cast polymer solution to moist air to form surface pores; (4) precipitating the cast polymer solution subjected to step (3) in a non-solvent to form internal pores and to solidify to prepare a membrane; (5) relates to a method for producing a microporous polyether sulfone membrane, comprising washing and drying the membrane.

Vapor induction phase transition, nonsolvent induction phase transition, composite pore former, polyether sulfone membrane

Description

Method of Preparing Polyethersulfone Membrane using Vapor Induced Phase Inversion and Nonsolvent Induced Phase Inversion}

1 illustrates a microporous polyethersulfone membrane prepared according to one embodiment of the present invention.

Figure 2 shows a microporous polyether sulfone membrane prepared according to one embodiment of the present invention.

Figure 3 shows a microporous polyether sulfone membrane prepared according to one embodiment of the present invention.

Figure 4 shows a microporous polyether sulfone membrane prepared according to one embodiment of the present invention.

5 shows a microporous polyethersulfone membrane prepared according to one embodiment of the present invention.

Figure 6 shows a microporous polyethersulfone membrane prepared according to one aspect of the present invention.

Figure 7 shows a microporous polyethersulfone membrane prepared according to one embodiment of the present invention.

8 shows a microporous polyethersulfone membrane prepared according to one embodiment of the present invention.

The present invention relates to a method for producing a microporous polyether sulfone membrane, and more particularly, to a method for producing a microporous polyether sulfone membrane based on a vapor induction phase transition process and a nonsolvent induction phase transition process and using a composite pore forming agent.

Polymer membranes are used for separation of liquids or gases in various fields including medicine, food, semiconductors and water treatment. The polymer membrane used in the above-mentioned field should be excellent in mechanical and thermal properties and chemical resistance properties, and is generally manufactured using polysulfone, polyethersulfone, polyamide, polyimide polymer, and the like.

The microporous polymer membrane is a method of casting a polymer solution and then evaporating a solvent and a non-solvent (dry process), and a method of casting a polymer solution and exposing it to steam so that the vapor is absorbed on an exposed surface (vapor induction phase transition, Vapor Induced Phase Inversion), casting a polymer solution and precipitating it in a non-solvent flocculation tank (Non-Solvent Induced Phase Inversion) or lowering the solubility of the polymer by lowering the temperature of the heated polymer casting film. Can be. It is known in the art how to prepare various polymer membranes based on the above methods.

Park, H.C. discloses a process for preparing polymer membranes using a vapor induction phase transition process and a nonsolvent induction phase transition process (Park, H.C. et al. Membr. Sci. 1999, vol. 1, p. 156). However, even when the two processes are used at the same time, sufficient pores cannot be formed.

US Pat. No. 5,886,059 relates to a method for producing an asymmetric polyethersulfone polymer membrane, comprising the steps of: (1) preparing a polymer solution by mixing a polyethersulfone polymer and a solvent, (2) adding a non-solvent to the polymer solution and uniformly Preparing a dispersion by mixing the same, (3) exposing the dispersion to a gaseous environment, and (4) precipitating the dispersion through the step into a quenching liquid to form a polyethersulfone polymer membrane. It consists of the steps of preparing and separating. However, when the additional pore-forming agent is not used as in US Pat. No. 5,886,059, the viscosity of the polymer solution is low, making it difficult to handle and produce a rigid polymer membrane.

US Pat. No. 6,056,903 relates to a method for preparing a polyethersulfone membrane, comprising the steps of: (1) preparing a casting solution comprising a polyethersulfone polymer, a solvent, and a lower aliphatic glycol; (3) exposing the coated support to an atmospheric condition, and (4) precipitating the exposed coated support to a precipitation bath containing lower aliphatic glycol and water to prepare a polyether sulfone membrane. (5) washing and drying the polyether sulfone membrane. However, even when using a single pore forming agent, such as US Pat. No. 6,056,903, it is difficult to form sufficient pores.

Chaturvedi B.K. discloses a method for producing a polymer membrane using a pore-forming agent and a non-solvent induction phase transition process. However, the non-solvent induction phase transition process alone cannot form sufficient pores on the surface of the polymer membrane.

Accordingly, the present invention provides a method for producing a polyether sulfone membrane which is easy to handle during the manufacturing process and enhances the mechanical strength by allowing sufficient pores to be formed on the surface and inside of the polyether sulfone membrane and increasing the viscosity of the polyether sulfone membrane polymer solution. I would like to.

To this end, the present inventors use a vapor induction phase transition process together with a non-solvent transition process to form sufficient pores on the surface and the inside of the polyether sulfone membrane, and use a complex pore-forming agent to increase the viscosity of the polyether sulfone polymer solution. As a result of preparing the polyether sulfone membrane, it was confirmed that sufficient pore was formed on the surface and the inside of the membrane to obtain a polyether sulfone membrane with enhanced mechanical strength.

In one aspect, the present invention provides a method for preparing a polymer solution comprising: (1) preparing a polymer solution by mixing a polymer polyether sulfone, a solvent, a first pore forming agent, and a second pore forming agent; (2) casting the polymer solution; (3) exposing the cast polymer solution to moist air to form surface pores; (4) precipitating the cast polymer solution subjected to step (3) in a non-solvent to form internal pores and solidify to prepare a membrane; (5) it provides a method for producing a microporous polyether sulfone membrane comprising the step of washing and drying the membrane.

The present invention comprises the steps of (1) preparing a polymer solution by mixing a polymer polyether sulfone, a solvent, a first pore-forming agent and a second pore-forming agent;

(2) casting the polymer solution;

(3) exposing the cast polymer solution to moist air to form surface pores;

(4) precipitating the cast polymer solution subjected to step (3) in a non-solvent to form internal pores and solidify to prepare a membrane;

(5) relates to a method for producing a microporous polyether sulfone membrane, comprising washing and drying the membrane.

In the present invention, "polyethersulfone" has a high resonance stability due to the coupling of a sulfone group and a phenyl group connected to an ether group, and because the sulfone group and the ether group block the activity of aromatic electrons, the membrane made of polyether sulfone is Excellent chemical, heat resistance and mechanical strength.

In the present invention, a solvent commonly used to prepare a polyether sulfone membrane may be used as the “solvent”, for example, N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), or dimethyl. Sulfoxide (DMSO), dimethylacetamide (DMAc), and the like.

In addition, in the present invention, any material that is well mixed with the solvent but not well mixed with the polyether sulfone polymer may be used as the “pore forming agent”. The present invention is characterized by using two pore-forming agents, wherein the liquid pore-forming agent is referred to as the first pore-forming agent, and the solid-phase pore-forming agent is referred to as the second pore-forming agent. In particular, the solid phase second pore-forming agent serves to increase the viscosity of the polymer solution.

As the first pore-forming agent, 2-ethoxyethanol (2-EE), propionic acid (PA), acetic acid, T-amyl alcohol (TAA), 2-methoxyethanol (2-ME), methanol, ethanol, butanol, Isopropyl alcohol or the like may be used, but is not limited thereto.

As the second pore-forming agent, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), silica (SiO ₂ ), or the like may be used, but is not limited thereto.

In addition, the "non-solvent" may be any material that is mixed with the solvent but not with the polymer, for example, alcohols such as water, methanol, ethanol and isopropanol may be used.

Step (1) of the preparation method according to the present invention is a step of preparing a polymer solution by mixing a polymer polyether sulfone, a solvent, a first pore former and a second pore former. At this time, the polymer solution comprises 6 to 25% by weight, preferably 9 to 16% by weight of the polyether sulfone per weight, 20 to 92% by weight, preferably 24 to 91% by weight of the solvent 1 to 70% by weight of the first pore-forming agent, preferably 1 to 60% by weight, and 1 to 40% by weight of the second pore-forming agent, preferably 1 to 10% by weight. It is preferable to manufacture and advance in nitrogen atmosphere.

Step (2) of the preparation method according to the invention is a step of casting the polymer solution prepared above. That is, in order to cast the polymer solution on a support, in the present invention, a support commonly used to prepare a polymer membrane in the art may be used, and it is preferable to use a support of polyester material.

Step (3) of the production method according to the invention is a step of exposing the cast polymer solution according to step (2) to moist air, based on a vapor induction phase transition process. In the process, pores are formed while the water vapor in the humid air is absorbed on the surface of the cast polymer solution, so that more pores are formed as more water vapor is present in the air. In step (3) of the present invention, the cast polymer solution is subjected to at least 50%, preferably at least 70%, more preferably at least 90%, in humid air having a humidity of 2 seconds to 5 minutes, preferably 2 seconds to Exposure for 1 minute, more preferably 2 to 30 seconds. On the other hand, since the humidity is changed by the temperature, it is suitable to maintain a temperature above room temperature so that the above-mentioned humidity can be maintained.

Step (4) of the manufacturing method according to the present invention is a step of precipitating the cast polymer solution passed through step (3) in the non-solvent to form pores and solidify, based on the non-solvent transfer process. In the present invention, since the pores are formed on the surface of the polymer solution through step (3), the non-solvent is easily accessible from the inside through the pores, so it is efficient to form the pores therein. The temperature of the non-solvent should be adjusted so as to allow smooth movement of the non-solvent through the pores, but not inhibit the coagulation of the polymer, at least 4 to 70 ℃ is suitable, 20 to 50 ℃ is preferred. Precipitating the polymer cast in the non-solvent at such a temperature for 1 to 20 hours, preferably 2 to 15 hours can form sufficient pores.

Step (5) of the manufacturing method according to the present invention is a step of washing and drying the coagulated membrane can remove the remaining solvent and pore-forming agent through the washing process. The washing process is a process of rinsing the membrane coagulated with water several times, in order to more effectively remove the remaining solvent and pore-forming agent, the temperature of the water is preferably 50 to 70 ° C. On the other hand, the drying process can be carried out according to a conventional method, for example, it is dried for 20 to 30 hours at a temperature of 60 to 80 ℃ in a dry oven.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only for illustrating the present invention specifically, and the scope of the present invention is not limited by these examples.

<Example 1>

In a suitable container at room temperature in a nitrogen atmosphere, 63% by weight of solvent N-methyl-2-pyrrolidone (NMP), 14% by weight of polyethersulfone as a polymer, 22% by weight of isopropyl alcohol as a first pore-forming agent, and second pores 1% by weight of polyvinylpyrrolidone (PVP) as a forming agent was added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 5 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 1, in the polyether sulfone membrane prepared according to Example 1, pores having a size of 0.1 to 3 μm were formed with pore formation of about 75%.

<Example 2>

38 wt% solvent N-methyl-2-pyrrolidone (NMP), 14 wt% polymer polyethersulfone, 2-ethoxyethanol (2-EE) as a first pore-forming agent in a suitable container at room temperature in a nitrogen atmosphere 44% by weight and 4% by weight of polyvinylpyrrolidone (PVP) as a second pore-forming agent were added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 2 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 2, in the polyether sulfone membrane prepared according to Example 2, pores having a size of 5 to 10 μm were formed with porosity of about 62%.

<Example 3>

N-methyl-2-pyrrolidone (NMP) as a solvent 36% by weight, polymer polyethersulfone 13% by weight, 2-methoxyethanol as the first pore-forming agent (2-ME) in a suitable container at room temperature in a nitrogen atmosphere. 48% by weight and 3% by weight of polyvinylpyrrolidone (PVP) as a second pore-forming agent were added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of steam for 15 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG. 3.

As shown in FIG. 3, in the polyether sulfone membrane prepared according to Example 3, pores having a size of 0.5 to 3 μm were formed with porosity of about 54%.

<Example 4>

N-methyl-2-pyrrolidone (NMP) as a solvent 28% by weight, polyethersulfone as a polymer 14% by weight, 2-methoxyethanol as the first pore-forming agent (2-ME) in a suitable container at room temperature in a nitrogen atmosphere. A polymer solution was prepared by adding 55% by weight of 4% by weight of polyethylene glycol (PEG) fraction molecular weight (MWCO) 2000 as a second pore-forming agent and dissolving it. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 90% of the evaporation humidity for 15 seconds, and exposed to 100% of water vapor for 2 seconds, followed by non-solvent water (20 ° C.). Precipitated for 12 hours to prepare a polymer membrane. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 4, in the polyether sulfone membrane prepared according to Example 4, pores having a size of 0.1 to 2 μm were formed with porosity of about 56%.

Example 5

36% by weight of solvent dimethyl sulfoxide (DMSO), 13% by weight of polyethersulfone as polymer, 48% by weight of 2-methoxyethanol (2-ME) as the first pore-forming agent, in a suitable container at room temperature in a nitrogen atmosphere. 3% by weight of polyvinylpyrrolidone (PVP), a pore-forming agent, was added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 2 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 5, in the polyether sulfone membrane prepared according to Example 5, pores having a size of 1 to 7 μm were formed with pore formation of about 72%.

<Example 6>

42 wt% of solvent N, N-dimethylformamide (DMP), 13 wt% of polyethersulfone as a polymer, 42 wt% of 2-methoxyethanol (2-ME) as a first pore-forming agent in a suitable container at room temperature in a nitrogen atmosphere. %, 3% by weight of polyvinylpyrrolidone (PVP) as a second pore-forming agent was added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 5 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 6, in the polyether sulfone membrane prepared according to Example 6, pores having a size of 1 to 8 μm were formed with porosity of about 73%.

<Example 7>

36% by weight of solvent dimethylacetamide (DMAc), 13% by weight of polyethersulfone as polymer, 48% by weight of 2-methoxyethanol (2-ME) as the first pore-forming agent, in a suitable container at room temperature in a nitrogen atmosphere. 3% by weight of polyvinylpyrrolidone (PVP), a pore-forming agent, was added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 5 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. Subsequently, after treatment and washing with distilled water at 70 ° C., the resultant was dried at a temperature of 70 ° C. in a dry oven for 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG.

As shown in FIG. 7, pores having a size of about 0.1 μm to about 2 μm were formed on the polyether sulfone membrane prepared according to Example 7 with a porosity of about 42%.

<Example 8>

43% by weight of solvent dimethylacetamide (DMAc), 16% by weight of polyethersulfone as polymer, 40% by weight of 2-ethoxyethanol (2-EE) as the first pore-forming agent, in a suitable container at room temperature in a nitrogen atmosphere. 1% by weight of polyvinylpyrrolidone (PVP), a pore-forming agent, was added and dissolved to prepare a polymer solution. While maintaining the polymer solution at 30 ° C., the thickness of the casting knife was adjusted to 200 μm, cast on a polyester support, exposed to 100% of water vapor for 5 seconds, and then precipitated in non-solvent water (20 ° C.) for 12 hours to prepare a polymer membrane. It was. After the post-treatment and washing with 70 ℃ distilled water and dried in a dry oven at a temperature of 70 ℃ 24 hours.

In order to confirm the shape, size and distribution of the pores of the polyether sulfone membrane thus prepared, it was observed by SEM and the results are shown in FIG. 8.

As illustrated in FIG. 8, in the polyether sulfone membrane prepared according to Example 8, pores having a size of 1 to 3 μm were formed with pore formation of about 76%.

Optimal conditions for producing the desired polyether sulfone membrane from the above Examples 1 to 8 is 10 to 15% by weight of polyether sulfone, N-methyl-2-pyrrolidone (NMP) 30 as a solvent To 35% by weight, 50 to 60% by weight of 2-ethoxyethanol (2-EE) as the first pore-forming agent, and as the second pore-forming agent After preparing and casting a polymer solution by mixing at least 1% by weight of polyvinylpyrrolidone (PVP), the polymer solution thus cast is exposed in humid air having a humidity of 90% or more for about 10 seconds and cast in a non-solvent transfer process. The prepared support was precipitated for 12 hours at a temperature of 20 ° C. of non-solvent water, and then treated and washed with 70 ° C. distilled water and dried at 70 ° C. for 24 hours in a dry oven.

The production method according to the present invention allows sufficient pores to be formed on the surface and the inside of the polyether sulfone membrane and increases the viscosity of the polyether sulfone membrane polymer solution, which is easy to handle during the manufacturing process and enhances the mechanical strength of the polyether sulfone membrane prepared therefrom. You can.

Claims (9)

(1) preparing a polymer solution by mixing a polymer polyether sulfone, a solvent, a first pore former, and a second pore former; (2) casting the polymer solution; (3) exposing the cast polymer solution to moist air to form surface pores; (4) precipitating the cast polymer solution subjected to step (3) in a non-solvent to form internal pores and solidify to prepare a membrane; (5) a method of producing a microporous polyether sulfone membrane, comprising washing and drying the membrane. The preparation of microporous polyether sulfone membrane according to claim 1, wherein the solvent is selected from the group consisting of N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide and dimethylacetamide. Way. The method of claim 1, wherein the first pore-forming agent is selected from the group consisting of 2-ethoxyethanol, propionic acid, acetic acid, T-amyl alcohol, 2-methoxyethanol, methanol, ethanol, butanol, isopropyl alcohol Method for producing a microporous polyether sulfone membrane characterized in that. The method of claim 1, wherein the second pore-forming agent is selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol and silica. The method of claim 1, wherein the non-solvent is selected from the group consisting of water, methanol, ethanol and isopropanol. The polymer solution of claim 1, wherein the polymer solution comprises 6 to 25% by weight of polyethersulfone, preferably 9 to 16% by weight, and 20 to 92% by weight of organic solvent, preferably 24 to 91% by weight. % To 1% to 70% by weight of the first pore-forming agent, preferably 1 to 60% by weight, and 1 to 40% by weight of the second pore-forming agent, preferably 1 to 10% by weight. Method for producing a microporous polyether sulfone membrane comprising a. 2. The method of claim 1, wherein step (3) exposes the polymer solution cast for 2 seconds to 5 minutes in humid air having a humidity of at least 50%. The method of producing a microporous polyether sulfone membrane according to claim 1, wherein the non-solvent of step (4) has a temperature of 4 to 70 ° C. The method of producing a microporous polyether sulfone membrane according to claim 1, wherein the precipitation of step (4) is performed for 1 to 20 hours.

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