Method for manufacturing nanofiltration membrane with improved flexibility

Abstract

The present invention relates to a method for manufacturing a nanofiltration membrane, in which cellulose is used as a support to manufacture a polybenzimidazole filtration, thus improving flexibility such that organic solvent permeability and a nanomaterial rejection rate are maintained constant before and after bending.

Description

Method for manufacturing a nanofiltration membrane with improved flexibility

[0001] The present invention relates to a method for manufacturing a nanofiltration membrane in which the flexibility is improved and the organic solvent permeability and nanomaterial exclusion rate are maintained constant before and after bending by manufacturing a polybenzimidazole membrane using cellulose as a support.

[0002]

[0003] A separation membrane refers to a thin membrane that selectively allows only the desired substance to pass through a mixture of various substances, and is classified into microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) membranes depending on the pore size.

[0004] While membrane processing technology has long been widely used in water treatment fields, such as wastewater purification or seawater desalination, for filtering out specific substances, research is currently underway to utilize membranes in various industries for the precise separation and purification of specific substances using organic solvents.

[0005] Organic solvents are used in various industries, such as removing impurities from high-purity materials like silicon wafers used in semiconductor manufacturing or cosmetics, as well as in the synthesis of pharmaceuticals and the production of basic chemical raw materials. In the final process, organic solvents used in the intermediate stages are heated and distilled or filtered through membranes, and the amount of waste organic solvents discarded during this process exceeds 2 million tons annually.

[0006] However, the organic solvent nanofiltration method using a separation membrane consumes less energy compared to the conventional distillation method that separates after heating, and can be applied to the separation of a wider variety of organic solvents, thereby increasing the recycling efficiency of organic solvents.

[0007] Polybenzimidazole membranes, which are conventionally used as organic solvent nanomembranes, are manufactured using polypropylene as a support, but they have the disadvantage that the polybenzimidazole layer is easily broken by external resistance and peels off from the polypropylene support after drying.

[0008] In addition, conventionally, separator membranes are wound in a spirally rolled state (bending) after drying for transport and storage, and then unwound for use; however, there may be cases where conventional polybenzimidazole separator membranes become unusable as separator membranes due to defects that occur after bending.

[0009]

[0010] The present invention provides a nanofiltration membrane with improved flexibility using a cellulose support that has a smaller pore size and is hydrophilic than a polypropylene support, and a method for manufacturing the same.

[0011] In addition, the present invention provides a nanofiltration membrane with improved flexibility that maintains performance, such as permeability and exclusion rate, for a long period without degradation even after bending, and a method for manufacturing the same.

[0012]

[0013] A method for manufacturing a nanofiltration membrane with improved flexibility according to the present invention may comprise: S1) a step of coating a dope solution containing polybenzimidazole onto a cellulose support; S2) a step of manufacturing a membrane by immersing the cellulose support coated with the dope solution in a non-solvent; and S3) a step of crosslinking the membrane manufactured in step S2) by immersing it in a crosslinking solution.

[0014] The above-mentioned crosslinking solution may be a polar aprotic solvent containing a crosslinking agent.

[0015] The above crosslinking agent may be a polyhalo-aromatic compound or a polyhalo-aliphatic compound.

[0016] The above polar aprotic solvent may include one or more selected from the group comprising acetonitrile (ACN), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO).

[0017] The content of the crosslinking agent contained in the above polar aprotic solvent may be 0.5 to 20 weight%.

[0018] The above dope solution may contain 5 to 30 weight percent of polybenzimidazole.

[0019] The thickness of the cellulose support may be 10 to 200 μm.

[0020] The pore size of the cellulose support may be 0.01 to 0.5 μm.

[0021] In step S1) above, the dope solution can be coated on the cellulose support to a thickness of 10 to 200 μm.

[0022] In addition, the present invention can provide a nanofiltration membrane with improved flexibility manufactured by the above manufacturing method.

[0023] The pore size of the above nanofiltration membrane may be 1 to 10 nm.

[0024] The thickness of the above nanofiltration membrane may be 10 to 300 μm.

[0025] The organic solvent permeability of the above nanofiltration membrane after bending can be 0.5 to 10 LMH / bar.

[0026] The nanomaterial exclusion rate after bending of the above nanofiltration membrane may be 80 to 100%.

[0027]

[0028] According to the present invention, a nanofiltration membrane manufactured using polybenzimidazole and a cellulose support has improved durability and flexibility due to the enhanced interfacial adhesion between the polybenzimidazole and the cellulose support.

[0029] In addition, the nanofiltration membrane according to the present invention has excellent resistance to mechanical stress such as bending, so no physical defects occur in the membrane, and has the advantage of maintaining high selectivity, such as organic solvent permeability and nanomaterial exclusion rate, consistently over the long term before and after bending.

[0030] Accordingly, the nanofiltration membrane according to the present invention can be used for an organic solvent nanofiltration process to separate nanomaterials mixed in an organic solvent.

[0031]

[0032] Figure 1 shows surface defects after bending of an embodiment according to the present invention.

[0033] Figure 2 shows surface defects after bending of a comparative example according to the present invention.

[0034] Figure 3 shows the ethanol (EtOH) permeability after bending of the examples and comparative examples according to the present invention.

[0035] Figure 4 shows the polypropylene glycol (PPG) exclusion rate after bending of the examples and comparative examples according to the present invention.

[0036]

[0037] The embodiments described in this specification may be modified in various different forms, and the technology according to one embodiment is not limited to the embodiments described below. Furthermore, the embodiments of one embodiment are provided to more fully explain the present disclosure to those with average knowledge in the relevant technical field. Unless otherwise defined, technical and scientific terms used herein have the meanings commonly understood by those with ordinary knowledge in the technical field to which this invention pertains, and descriptions of known functions and configurations that may unnecessarily obscure the essence of the present invention are omitted in the following description and accompanying drawings.

[0038] Additionally, the singular form used in this specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0039] Furthermore, in this specification and the appended claims, terms such as "first," "second," etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another.

[0040] Furthermore, in this specification and the appended claims, when a part such as a film (layer), region, or component is described as being located "on," "on top," "on the upper," "under," "on the lower," or "on the lower" of another part, this includes not only cases where a part is in contact with another part, but also cases where another part exists between the two parts.

[0041] Furthermore, terms such as "approximately" and "substantially" as used in this specification and the appended claims are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said meaning, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding this specification and the appended claims.

[0042] Additionally, numeric ranges used in this specification include lower and upper limits and all values ​​within the range, increments logically derived from the shape and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numeric ranges limited in different forms.

[0043] Furthermore, in this specification and the appended claims, terms such as "comprising" or "having" mean that the features or components described in the specification exist, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

[0044] Additionally, in this specification, the term "cellulose support" is used to mean including a regenerated cellulose support.

[0045] Hereinafter, a method for manufacturing a nanofiltration membrane with improved flexibility according to the present invention will be described in detail with reference to the attached drawings.

[0046]

[0047] The present invention aims to solve the problem that polybenzimidazole separators manufactured using conventional polypropylene as a support are easily broken by external resistance and peel off from the support, and that performance such as permeability and exclusion rate is degraded due to physical defects.

[0048] The present invention enables the production of a high-density separation membrane using a small amount of polymer solution by using cellulose as a support, and has the advantage of improved flexibility of the separation membrane resulting in excellent resistance to bending, as well as maintaining organic solvent permeability and nanomaterial exclusion rate consistently over the long term before and after bending.

[0049] A method for manufacturing a nanofiltration membrane with improved flexibility according to the present invention may include: S1) a step of coating a dope solution containing polybenzimidazole onto a cellulose support; S2) a step of manufacturing a membrane by immersing the cellulose support coated with the dope solution in a non-solvent; and S3) a step of crosslinking the membrane manufactured in step S2) by immersing it in a crosslinking solution.

[0050] Step S1) above can form a polybenzimidazole coating layer by coating a dope solution, prepared by dissolving polybenzimidazole in an organic solvent and stirring, onto a cellulose support.

[0051] In one embodiment, the dope solution may contain polybenzimidazole in a range of 5% by weight or more, 10% by weight or more, 15% by weight or more, 30% by weight or less, 25% by weight or less, or between any two of the values ​​described herein. For example, it may be 5 to 30% by weight, 10 to 25% by weight, or 15 to 25% by weight, but is not limited thereto. When manufacturing a separation membrane with a dope solution containing polybenzimidazole in the above range, the polybenzimidazole is evenly dissolved at a suitable concentration to form a separation membrane of uniform thickness, which may be preferred, but is not particularly limited as long as the effects of the present invention are achieved.

[0052] In one embodiment, the number average molecular weight (Mn) of the polybenzimidazole may be 10,000 g / mol or more, 20,000 g / mol or more, 100,000 g / mol or less, 90,000 g / mol or less, 80,000 g / mol or less, 70,000 g / mol or less, 60,000 g / mol or less, 50,000 g / mol or less, or within a range between any two of the values ​​listed herein. For example, it may be 10,000 to 100,000 g / mol, 20,000 to 90,000 g / mol, or 20,000 to 50,000 g / mol, but is not limited thereto.

[0053] As an example, the organic solvent may be used without particular limitation as long as it is capable of dissolving polybenzimidazole. For example, it may include one or more selected from the group comprising acetonitrile (ACN), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO). The organic solvent may be superior in solubility measurements if it contains acetonitrile, and preferably may be a mixed solvent of acetonitrile and dimethylacetamide, but is not limited thereto.

[0054] As an example, the stirring time is not particularly limited as long as the effect of the present invention is achieved, and may be 1 hour or more, 2 hours or more, 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more, 24 hours or less, 22 hours or less, 20 hours or less, 18 hours or less, 16 hours or less, 14 hours or less, 12 hours or less, or within a range between any two values ​​among those described herein. For example, it may be 1 to 24 hours, 3 to 18 hours, or 6 to 12 hours, but is not limited thereto.

[0055] In addition, the solution stirred in step S1) above may be left at room temperature for at least 12 hours to remove air bubbles in the solution. The above time is not specifically limited as long as the effects of the present invention are achieved.

[0056] In one embodiment, the present invention uses a cellulose support compared to a conventional polypropylene support, thereby improving the permeability of organic solvents such as ethanol (EtOH) and the exclusion rate of polyalkylene glycols such as polypropylene glycol (PPG), which can increase the selectivity of the separation membrane. These characteristics appear to be derived from the molecular structure and pore characteristics of cellulose, and appear to be achieved by combining with the cross-linked polybenzimidazole in the present invention.

[0057] As one embodiment, the thickness of the cellulose support is not particularly limited as long as the effect of the present invention is achieved, and may be 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 200 μm or less, 150 μm or less, 100 μm or less, or within a range between any two values ​​among those described herein. For example, it may be 10 to 200 μm, 30 to 150 μm, or 50 to 100 μm, but is not limited thereto.

[0058] As one embodiment, the pore size of the cellulose support is not particularly limited as long as the effect of the present invention is achieved, and may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or within a range between any two of the values ​​described herein. For example, it may be 0.01 to 0.5 μm, 0.05 to 0.4 μm, or 0.1 to 0.3 μm, but is not limited thereto.

[0059] In one embodiment, the thickness of the dope solution coated on the cellulose support in step S1) may be 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 200 μm or less, 150 μm or less, 100 μm or less, or within a range between any two of the values ​​described herein. For example, it may be 10 to 200 μm, 30 to 150 μm, or 50 to 100 μm, but is not limited thereto. When coated with a thickness within the above range, the separation membrane may be preferred as it can have excellent permeability and excellent mechanical strength at the same time, but is not particularly limited as long as the effects of the present invention are achieved.

[0060] In one embodiment, the coating in step S1) can be used without particular limitation as long as it is a method capable of coating the dope solution onto a cellulose support. For example, methods such as casting, slot-die coating, spin coating, spray coating, dip coating, roll-to-roll coating, and drop casting may be selected. Preferably, it may be casting, but is not limited thereto.

[0061] Step S2) above can manufacture a separation membrane by immersing the cellulose support coated with the dope solution in a non-solvent to induce phase transition and solidification through mutual diffusion between the solvent and the non-solvent.

[0062] In one embodiment, the non-solvent may be used without particular limitation as long as it is soluble in a solvent but cannot dissolve the polybenzimidazole contained in the dope solution. For example, it may include one or more selected from the group comprising distilled water, acetonitrile (ACN), 2-pyrrolidone (2P), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO). Preferably, it may be distilled water, but is not limited thereto.

[0063] In one embodiment, the temperature of the non-solvent is not particularly limited as long as it is below the boiling point of the non-solvent, and may be within a range of 10°C or higher, 15°C or higher, 20°C or higher, 50°C or lower, 40°C or lower, 30°C or lower, or between any two of the values ​​listed herein. For example, a separation membrane may be formed by immersing in a water bath containing distilled water at 10 to 50°C, 15 to 40°C, or 20 to 30°C.

[0064] As one embodiment, the immersion time is not particularly limited as long as the effect of the present invention is achieved, and may be 1 hour or more, 6 hours or more, 12 hours or more, 48 hours or less, 36 hours or less, 24 hours or less, or within a range between any two values ​​among those described herein. For example, it may be 1 to 48 hours, 6 to 36 hours, or 12 to 24 hours, but is not limited thereto.

[0065] The separation membrane prepared by solidifying the polybenzimidazole in step S2) above can be stored by immersing it in purified distilled water for at least 24 hours to remove residual solvent, and then immersing it in an alcohol-based non-solvent such as isopropyl alcohol (IPA) that has no physical or chemical effect on the cellulose or polybenzimidazole.

[0066] Step S3) above can produce a nanofiltration membrane by crosslinking the membrane produced in Step S2), and the crosslinking network between the polybenzimidazole polymer chains can be formed to further improve the solvent resistance of the membrane.

[0067] In one embodiment, step S3) may proceed with crosslinking while refluxing the crosslinking solution. Accordingly, crosslinking proceeds uniformly, allowing for the production of a nanofiltration membrane with improved durability and separation performance.

[0068] As one embodiment, the crosslinking solution is not particularly limited as long as it achieves the effects of the present invention, and preferably may be a polar aprotic solvent containing a crosslinking agent, but is not limited thereto.

[0069] As an example, the crosslinking agent is not particularly limited as long as it achieves the effects of the present invention, and may be, for example, a polyhaloaromatic compound or a polyhaloaliphatic compound, but is not limited thereto. Preferably, a polyhaloaromatic compound with good reactivity is preferred, and non-limiting examples may include dihalobenzene, dihaloxylene, dihalotoluene, trihalobenzene, etc., and preferably may be dihaloxylene, but is not limited thereto.

[0070] As one embodiment, the polar aprotic solvent is not particularly limited as long as it achieves the effects of the present invention, and may include, for example, one or more selected from the group comprising acetonitrile (ACN), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO). Preferably, it may be acetonitrile (ACN), but is not limited thereto.

[0071] As one embodiment, the content of the crosslinking agent contained in the polar aprotic solvent is not particularly limited as long as the effect of the present invention is achieved, and may be included in a range of 0.5 wt% or more, 1 wt% or more, 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or between any two values ​​among those described herein. For example, it may be 0.5 to 20 wt%, 1 to 10 wt%, or 1 to 5 wt%, but is not limited thereto.

[0072] In one embodiment, when crosslinking is performed using a crosslinking solution containing dibromoparaxylene in an acetonitrile solvent, the crosslinking reaction occurs efficiently both externally and internally in the membrane, which can effectively improve the durability and separation performance of the membrane, but is not limited thereto.

[0073] As an example, the crosslinking temperature is not particularly limited as long as the effects of the present invention are achieved, and may be within a range of 30°C or higher, 40°C or higher, 50°C or higher, 100°C or lower, 90°C or lower, 80°C or lower, or between any two values ​​listed herein. For example, it may be 30 to 100°C, 40 to 90°C, or 50 to 80°C, but is not limited thereto. In addition, the crosslinking time is not particularly limited as long as the effects of the present invention are achieved, and may be within a range of 5 hours or more, 10 hours or more, 15 hours or more, 48 hours or less, 36 hours or less, 24 hours or less, or between any two values ​​listed herein. For example, it may be 5 to 48 hours, 10 to 36 hours, or 15 to 24 hours, but is not limited thereto. When crosslinking at the temperature and time ranges mentioned above, the pore structure of the separation membrane can be made denser, thereby improving organic solvent permeability and nanomaterial exclusion rate.

[0074] In one embodiment, the membrane prepared in step S2) may be immersed in a polar aprotic solvent identical to the crosslinking solution before proceeding with crosslinking to remove residual isopropyl alcohol. The polar aprotic solvent is not particularly limited as long as it achieves the effects of the present invention, and preferably may be acetonitrile (ACN), but is not limited thereto. Accordingly, the non-heterogeneous solvent is removed, thereby increasing the crosslinking efficiency and shortening the crosslinking time.

[0075] In addition, as one embodiment, the nanofiltration membrane may be washed with a polar aprotic solvent identical to the crosslinking solution to remove unreacted materials, and then stored by immersing it in an alcohol-based nonsolvent such as isopropyl alcohol (IPA) that has no physical or chemical effect on the cellulose or polybenzimidazole.

[0076] The nanofiltration membrane manufactured by the above method is described below.

[0077] The nanofiltration membrane according to the present invention can be used for an organic solvent nanofiltration process to separate nanomaterials mixed in an organic solvent.

[0078] In one embodiment, the pore size of the nanofiltration membrane may be 1 nm or more, 2 nm or more, 10 nm or less, 9 nm or less, 8 nm or less, or within a range between any two of the values ​​described herein. For example, it may be 1 to 10 nm, 2 to 9 nm, or 2 to 8 nm, but is not limited thereto. When having a pore size within the above range, excellent organic solvent permeability and nanomaterial exclusion rate may be achieved.

[0079] In one embodiment, the thickness of the nanofiltration membrane may be 10 μm or more, 20 μm or more, 30 μm or more, 300 μm or less, 250 μm or less, 200 μm or less, or within a range between any two of the values ​​described herein. For example, it may be 10 to 300 μm, 20 to 250 μm, or 30 to 200 μm, but is not limited thereto. When having a thickness within the above range, it may have high chemical resistance and stability in organic solvents, and may improve organic solvent permeability and nanomaterial exclusion rate.

[0080] In one embodiment, the nanofiltration membrane separates nanomaterials in an organic solvent, and the nanomaterials are not particularly limited but may be organic materials, inorganic materials, or a mixture thereof. For example, they separate organic materials with large molecular weights in an organic solvent, and preferably, they separate polyalkylene glycols contained in the organic solvent, but are not limited thereto.

[0081] In one embodiment, the organic solvent is not particularly limited in type, but may include one or more selected from the group comprising, for example, methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran, acetonitrile, N-methyl-2-pyrrolidone, dimethylformamide, diethylformamide, dimethylacetamide, dimethyl sulfoxide, dichloromethane, methyl ethyl ketone, formaldehyde, diethyl ether, benzene, toluene, and xylene, but is not limited thereto.

[0082] In one embodiment, the number average molecular weight (Mn) of the polyalkylene glycol may be 100 g / mol or more, 150 g / mol or more, 200 g / mol or more, 250 g / mol or more, 300 g / mol or more, 2,000 g / mol or less, 1,500 g / mol or less, 1,000 g / mol or less, or within a range between any two of the values ​​listed herein. For example, it may be 100 to 2,000 g / mol, 200 to 1,500 g / mol, or 300 to 1,000 g / mol, but is not limited thereto.

[0083] In addition, the nanofiltration membrane according to the present invention maintains its performance, such as organic solvent permeability and nanomaterial exclusion rate, for a long period without degradation even after bending (wrapping into a spiral shape) following drying.

[0084] In one embodiment, the organic solvent permeability of the nanofiltration membrane after bending may be 0.5 LMH / bar or higher, 1 LMH / bar or higher, 10 LMH / bar or lower, 5 LMH / bar or lower, 3 LMH / bar or lower, or within a range between any two of the values ​​described herein. For example, it may be 0.5 to 10 LMH / bar, 1 to 5 LMH / bar, or 1 to 3 LMH / bar, but is not limited thereto. (LMH is L / (m 2 ·h) represents the permeation rate per membrane area per hour.

[0085] In one embodiment, the nanomaterial exclusion rate after bending of the nanofiltration membrane may be 80% or more, 85% or more, 90% or more, 100% or less, or within a range between any two of the values ​​described herein. For example, it may be 80 to 100%, 85 to 100%, or 90 to 100%, but is not limited thereto.

[0086]

[0087] Examples and experimental examples are described below with specific examples. However, the examples and experimental examples described below are merely illustrative of some aspects, and the technology described in this specification is not limited thereto.

[0088]

[0089] <Example>

[0090] A dope solution was prepared by dissolving 38 g of polybenzimidazole (PBI 26 wt% diluted in DMAc) with a number average molecular weight of 27,000 g / mol in 20 g of a solution of acetonitrile and dimethylacetamide mixed in a weight ratio of 2:3, stirring at room temperature for 6 hours using a mechanical stirrer, and removing bubbles. Subsequently, the dope solution was coated by casting it to a thickness of 100 μm onto a cellulose support (average thickness 75 μm, average pore size diameter 0.2 μm) at room temperature. A separation membrane was prepared by immersing the cellulose support coated with the dope solution in a water bath for at least 1 hour, then immersing it in water for 24 hours to remove residual solvent, and storing it in isopropyl alcohol. A nanofiltration membrane was prepared by immersing a circular membrane cut to a diameter of 7 cm in a crosslinking solution in which 9.6 g of dibromoparaxylene was dissolved in 310.4 g of acetonitrile, and then crosslinking it for 24 hours while refluxing at 80 ℃. Using the prepared membrane, flexibility for bending, ethanol (EtOH) permeability, and polypropylene glycol (PPG) exclusion rate were measured in the following manner.

[0091]

[0092] <Comparative Example>

[0093] The procedure was carried out in the same manner as in the above example, except that a polypropylene non-woven fabric was used as the support. Using the prepared separator, the flexibility for bending, ethanol (EtOH) permeability, and polypropylene glycol (PPG) exclusion rate were measured in the following manner.

[0094]

[0095] <Experimental Example 1> Flexibility Measurement

[0096] The nanofiltration membranes of the examples and comparative examples were placed between ceramic plates and dried for a certain period (3 and 10 days). The un-dried membrane (Bara), the membrane dried for 3 days (3D-B), and the membrane dried for 10 days (10D-B) were spirally rolled into a 7 mm diameter tube and stored for one day. That is, the flexibility and surface defects of the membranes were evaluated through bending (spiral rolling).

[0097] Figure 1 shows surface defects after bending of an embodiment according to the present invention, and Figure 2 shows surface defects after bending of a comparative example according to the present invention. The nanofiltration membrane of the embodiment did not break when bent after drying for 3 days (3D-B) and 10 days (10D-B), but the nanofiltration membrane of the comparative example broke when bent after drying for 3 days (3D-B) and 10 days (10D-B).

[0098]

[0099] <Experimental Example 2> Measurement of Ethanol (EtOH) Permeability and Polypropylene Glycol (PPG) Exclusion Rate

[0100] The nanofiltration membranes of the example and comparative example bent in Experimental Example 1 above were recovered, mounted in a cross-flow device, stabilized with pure ethanol (EtOH) for 1 hour, and then the permeability was measured, with an effective area of ​​14.8 cm² 2Performance evaluation was conducted under conditions of an operating pressure of 15 bar, a temperature of 30 ℃, and a flow rate of 100 L / h.

[0101] Afterward, an ethanol solution containing polypropylene glycol (PPG) was added, and the exclusion rate was measured by liquid chromatography using the permeated sample after 1 hour. The number average molecular weight (Mn) of polypropylene glycol is 425 g / mol or less, 700 g / mol or less, and 1000 g / mol or less, respectively.

[0102] Figure 3 shows the ethanol (EtOH) permeability after bending of the example and comparative example according to the present invention. The nanofiltration membrane of the example maintained a constant EtOH permeability even after bending, whereas the nanofiltration membrane of the comparative example showed an increase in EtOH permeability after bending. Therefore, it was confirmed that compared to the nanofiltration membrane of the comparative example, the nanofiltration membrane of the example did not develop physical defects after bending, and thus the organic solvent permeability (EtOH permeability) remained constant before and after bending.

[0103] Figure 4 shows the polypropylene glycol (PPG) exclusion rate after bending of the example and comparative example according to the present invention. The nanofiltration membrane of the example maintained a constant PPG exclusion rate even after bending, whereas the nanofiltration membrane of the comparative example showed a decrease in the PPG exclusion rate after bending. Therefore, it was confirmed that compared to the nanofiltration membrane of the comparative example, the nanofiltration membrane of the example did not develop physical defects after bending, and thus the nanomaterial exclusion rate (PPG exclusion rate) remained constant before and after bending.

[0104]

[0105] As described above, the present invention has been explained in this specification by specific details and limited embodiments, but this is provided only to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. A person skilled in the art to which the invention pertains can make various modifications and variations from this description. Accordingly, the concept described in this specification should not be limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims themselves, shall be considered to fall within the scope of the concept described in this specification.

Claims

1. S1) A step of coating a dope solution containing polybenzimidazole onto a cellulose support; S2) A step of preparing a separation membrane by immersing a cellulose support coated with the above dope solution in a non-solvent; and S3) A step of immersing the separation membrane prepared in step S2) above in a crosslinking solution to crosslink it; A method for manufacturing a nanofiltration membrane comprising 2. In Paragraph 1, The above crosslinking solution is a polar aprotic solvent containing a crosslinking agent, and is a method for manufacturing a nanofiltration membrane.

3. In Paragraph 2, A method for manufacturing a nanofiltration membrane in which the crosslinking agent is a polyhaloaromatic compound or a polyhaloaliphatic compound.

4. In Paragraph 2, A method for preparing a nanofiltration membrane comprising one or more selected from the group including acetonitrile (ACN), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO), wherein the polar aprotic solvent is one or more.

5. In Paragraph 2, A method for manufacturing a nanofiltration membrane in which the content of the crosslinking agent contained in the above polar aprotic solvent is 0.5 to 20 weight%.

6. In Paragraph 1, A method for manufacturing a nanofiltration membrane comprising 5 to 30 weight% of polybenzimidazole in the above dope solution.

7. In Paragraph 1, A method for manufacturing a nanofiltration membrane in which the thickness of the cellulose support is 10 to 200 μm.

8. In Paragraph 1, A method for manufacturing a nanofiltration membrane having a pore size of 0.01 to 0.5 μm of the cellulose support.

9. In Paragraph 1, A method for manufacturing a nanofiltration membrane in which, in step S1) above, the dope solution is coated onto the cellulose support to a thickness of 10 to 200 μm.

10. A nanofiltration membrane manufactured by the method of any one of claims 1 to 9.

11. In Paragraph 10, A nanofiltration membrane having a pore size of 1 to 10 nm.

12. In Paragraph 10, A nanofiltration membrane having a thickness of 10 to 300 μm.

13. In Paragraph 10, A nanofiltration membrane having an organic solvent permeability of 0.5 to 10 LMH / bar after bending.

14. In Paragraph 10, A nanofiltration membrane having a nanomaterial exclusion rate of 80 to 100% after bending.

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