Method for producing hydrophilic microporous membrane for virus filtration

Abstract

The present invention relates to a method for manufacturing a hydrophilic microporous membrane for virus filtration. Specifically, the hydrophilic microporous membrane is manufactured by performing a hydrophilic treatment without using a crosslinking agent, and the microporous membrane for virus removal thus manufactured has excellent water permeability and protein permeability and exhibits good durability against organic solvents (alcohols).

Description

Method for manufacturing a hydrophilic microporous membrane for virus filtration

[0001] The present invention relates to a method for manufacturing a hydrophilic microporous membrane for virus filtration.

[0002] When preparations containing biopharmaceuticals are administered to the human body, viruses that may be present in the preparation pose a risk of causing serious problems. Therefore, a process to remove viruses is necessary during the manufacturing of biopharmaceuticals. Among these methods, membrane filtration, which physically removes viruses, is an effective technique capable of eliminating viruses without altering useful proteins.

[0003] A membrane for virus removal must be a hydrophilic membrane to prevent blockage caused by the adsorption of proteins. Korean Registered Patent No. 10-0805977 discloses a method for producing a hydrophilized microporous membrane for virus removal by contacting a thermoplastic resin, polyvinylidene fluoride (PVDF) resin, with a reaction solution containing a hydrophilic monomer and a crosslinking agent.

[0004] However, when the hydrophilization treatment of the membrane is performed using the aforementioned method, although hydrophilicity can be obtained, there are problems such as severe adhesion between membranes and lower water permeability compared to hydrophobic membranes, making it difficult to use as a membrane for virus removal.

[0005]

[0006] Accordingly, the inventors continued their research to solve the aforementioned problems and developed a microporous membrane for virus removal that has superior water and protein permeability compared to conventional technology and good durability against organic solvents (alcohols), thereby arriving at the present invention.

[0007] The objective of the present invention is to provide a method for manufacturing a hydrophilic microporous membrane for virus filtration that has excellent water and protein permeability and good durability against organic solvents (alcohols).

[0008] Another objective of the present invention is to provide a hydrophilic microporous membrane for virus filtration manufactured by the above method.

[0009]

[0010] However, the technical problems that the present invention aims to solve are not limited to the purposes mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0011] To solve the above problem, the present invention provides a method for manufacturing a microporous membrane for virus filtration comprising the following steps:

[0012] A reaction solution for hydrophilization treatment comprising less than 3 volume% of a hydrophilic vinyl monomer having one vinyl group relative to the total volume of the reaction solution; and a step of performing hydrophilization treatment by grafting by contacting a polyvinylidene fluoride (PVDF) microporous membrane and maintaining it for at least 12 hours, wherein the reaction solution for hydrophilization treatment does not contain a crosslinking agent.

[0013] The hydrophilic vinyl monomer having one vinyl group above may be hydroxypropyl acrylate or hydroxybutyl acrylate.

[0014] The above reaction solution can be prepared by nitrogen bubbling treatment for less than 60 minutes at a temperature of 20 ℃ or lower.

[0015] The hydrophilic vinyl monomer having one vinyl group may be 0.01 to 2 volume% of the total volume of the hydrophilization treatment reaction solution.

[0016] Hydrophilization treatment can be performed by contacting the PVDF with the above reaction solution and maintaining it for 12 to 24 hours.

[0017] The above PVDF can be contacted with the above reaction solution to perform hydrophilization treatment at a temperature of 20°C or lower.

[0018] The water permeability of the hydrophilic microporous membrane after the above hydrophilization treatment step may be 50 LMH / bar or higher.

[0019] After the hydrophilization treatment step, the graft rate of the hydrophilic layer of the microporous membrane may be less than 3.5%.

[0020] After the hydrophilization treatment step, the water flux variation of the hydrophilic microporous membrane may be less than 4%.

[0021] A microporous membrane for virus removal prepared by performing a hydrophilization treatment without using a crosslinking agent according to the present invention provides excellent water permeability and protein permeability. Furthermore, the present invention does not use a crosslinking agent and provides performance equivalent to or better than that of existing technologies in terms of durability against organic solvents (alcohols), even though the graft rate is lower.

[0022] In one aspect, the present invention relates to a method for manufacturing a microporous membrane for virus filtration comprising the following steps:

[0023] A reaction solution for hydrophilization treatment comprising less than 3 volume% of a hydrophilic vinyl monomer having one vinyl group relative to the total volume of the reaction solution; and a step of performing hydrophilization treatment by grafting by contacting a polyvinylidene fluoride (PVDF) microporous membrane and maintaining it for at least 12 hours, wherein the reaction solution for hydrophilization treatment does not contain a crosslinking agent.

[0024] The above PVDF resin is a material with excellent heat resistance and moldability, and is widely used in this technical field for virus removal membranes.

[0025] The term “hydrophilization treatment by grafting” refers to a method of grafting hydrophilic monomers onto the surface of a porous membrane to form a chemical bond between the parent membrane and the hydrophilic layer, thereby increasing the durability of the hydrophilized microporous membrane.

[0026] The hydrophilic vinyl monomer having one vinyl group is a monomer having one vinyl group that dissolves uniformly when 1 volume% is mixed in pure water at 25°C under atmospheric pressure. The hydrophilic vinyl monomer may be hydroxypropyl acrylate or hydroxybutyl acrylate.

[0027] In one embodiment, the hydrophilic vinyl monomer having one vinyl group may be 0.01 to 2 volume% with respect to the total volume of the hydrophilization treatment reaction solution.

[0028] The present invention does not use a crosslinking agent, that is, a vinyl monomer having two or more vinyl groups, such as ethylene glycol dimethacrylate, polydiethylene glycol dimethacrylate, ethylene glycol diacrylate, polydiethylene glycol diacrylate, etc.

[0029] It is generally known that when a crosslinking agent is not used, a higher concentration of hydrophilic vinyl monomer must be added compared to when a crosslinking agent is used. However, the present invention provides optimal conditions for introducing a thin hydrophilic coating layer while using a small amount of hydrophilic vinyl monomer, such as 3 volume% or less, more preferably 2 volume% or less, and even more preferably 1 volume% or less.

[0030] Specifically, the concentration of the hydrophilic vinyl monomer is lowered, and the PVDF membrane and the reaction solution are reacted at a temperature of 20°C for more than 12 hours. Such conditions have the advantage of allowing for easy control of the reaction.

[0031] Furthermore, the reaction conditions of the present invention inhibit the excessive growth of hydrophilic polymers, thereby preventing adhesion between microporous membranes. Additionally, a hydrophilic microporous membrane prepared under the conditions according to the present invention can have a thin hydrophilic coating layer introduced. Compared to conventional microporous membranes, this thin coating layer provides the effect of preventing swelling of the hydrophilic polymer layer, preventing protein adsorption, and not significantly reducing water permeability. In other words, the microporous membrane according to the present invention has superior water permeability and protein permeability compared to conventional membranes, and exhibits good durability against organic solvents (alcohols).

[0032] In one embodiment, the reaction solution may be prepared by nitrogen bubbling treatment for less than 60 minutes at a temperature of 20°C or lower. If the temperature exceeds 20°C, there is a problem of excessive application of the hydrophilic coating layer, and if the nitrogen bubbling time is less than 60 minutes, preferably 30 minutes or less, there is a possibility that the hydrophilic coating will not be properly formed due to the introduction of oxygen.

[0033] In one embodiment, hydrophilization treatment can be performed by contacting the PVDF with the reaction solution and maintaining it for 12 to 24 hours. If the time range is exceeded, a disadvantage may occur in which the hydrophilic layer is not formed properly or the thickness of the hydrophilic layer becomes too thick, resulting in a severe decrease in permeability.

[0034] In one embodiment, the PVDF can be contacted with the reaction solution to perform a hydrophilization treatment at a temperature of 20°C or lower. At a temperature exceeding 20°C, a disadvantage may occur in which the thickness of the hydrophilic layer becomes thicker.

[0035] In one embodiment, the hydrophilic membrane water permeability of the hydrophilic microporous membrane after the hydrophilization treatment step may be 50 LMH / bar or higher. Preferably, it may be 51 LMH / bar or higher, more preferably 52 LMH / bar or higher, and even more preferably 53 LMH / bar or higher, and does not exceed 60 LMH / bar.

[0036] In one embodiment, after the hydrophilization treatment step, the graft rate of the hydrophilic layer of the microporous membrane may be less than 3.5%. Preferably, it may be less than 3.2%, more preferably less than 3.1%, and even more preferably less than 3%.

[0037] In one embodiment, after the hydrophilization treatment step, the water permeability deviation of the microporous membrane may be less than 4%.

[0038] In the present invention, the term “water permeability deviation” refers to the amount of change in water permeability when a hydrophilic microporous membrane is permeated with pure water, and then permeated at 1 bar after permeating at 3 bar for 1 hour. It can be seen that the water permeability deviation of the microporous membrane according to the present invention is such that no problem of water permeability decreasing due to swelling occurs.

[0039]

[0040] The present invention is capable of various modifications and may have various embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description below. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. In describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions may obscure the essence of the present invention.

[0041]

[0042] [Example]

[0043] The present invention will be explained in detail below through examples.

[0044] However, the following examples are merely illustrative of the present invention, and the content of the present invention is not limited by the following examples.

[0045]

[0046] <Example 1>

[0047] The reaction solution was prepared as follows: Hydroxypropyl Acrylate (TCI, reagent grade) was dissolved in a 25 volume% aqueous solution of 3-butanol (Daejeong Chemical, reagent grade) to a volume% of 1 volume%, and nitrogen bubbling was performed for 20 minutes while maintaining the temperature at 20 degrees. Polyvinylidene fluoride resin (solvay, pellets) was prepared. First, polyvinylidene fluoride resin (hereinafter also referred to as "membrane") was packaged in a packaging paper (PP spout pouch), and the polyvinylidene fluoride was stored under a nitrogen atmosphere by repeating the vacuum-nitrogen injection process 5 times. Then, it was packaged in a Styrofoam box with dry ice and cooled to -60°C while irradiating with gamma rays at 50 kGy using Co60 as the source. After the above investigation, for the hydrophilization treatment of the membrane by grafting, the 1 volume% reaction solution prepared above was reacted at 20°C for 12 hours while contacting it with the membrane at a ratio of 100ml per 1g of membrane. Subsequently, the membrane was washed three times with ethanol at 50°C for 24 hours and vacuum dried at 60°C for 8 hours to obtain a hydrophilic membrane. It was confirmed that the obtained hydrophilic membrane became transparent when immersed in water. The performance of the obtained membrane is shown in Table 1 below.

[0048]

[0049] <Example 2>

[0050] A hydrophilic membrane was obtained in the same manner as in Example 1, except that the reaction solution was prepared such that the hydroxypropyl acrylate content was 2 volume%.

[0051]

[0052] <Example 3>

[0053] A hydrophilic membrane was obtained using the same method as in Example 1, except that during the hydrophilization treatment of the membrane prepared by the method of Example 1, a 1 volume% reaction solution was contacted at a ratio of 100 ml per 1 g of membrane and reacted for 24 hours.

[0054]

[0055] <Comparative Example 1>

[0056] The reaction solution was prepared as follows: Hydroxypropyl Acrylate (TCI, reagent grade) was dissolved in a 25 volume% aqueous solution of 3-butanol (Daejeong Chemical, reagent grade) to a volume of 8 volume%, and nitrogen bubbling was performed for 20 minutes while maintaining the temperature at 20 degrees. Polyvinylidene fluoride membrane resin (solvay, pellets) was prepared. First, the polyvinylidene fluoride membrane resin was packaged in a packaging paper (PP spout pouch), and the membrane was stored under a nitrogen atmosphere by repeating the vacuum-nitrogen injection process 5 times. Then, it was packaged in a styrofoam box with dry ice and cooled to -60 ℃ while irradiating with gamma rays at 50 kGy using CO60 as the source. After the above investigation, for the hydrophilization treatment of the membrane by grafting, the 1 volume% reaction solution prepared above was reacted at 40°C for 1 hour while contacting it with 100ml per 1g of membrane. Subsequently, the membrane was washed three times with ethanol at 50°C for 24 hours and vacuum dried at 60°C for 8 hours to obtain a hydrophilic membrane. The performance of the obtained membrane is shown in Table 2 below.

[0057]

[0058] <Comparative Example 2>

[0059] A reaction solution was prepared under the same conditions as Comparative Example 1, except that hydroxypropyl acrylate was dissolved in a 25 volume% aqueous solution of 3-butanol to a concentration of 1.23 volume%, polyethylene glycol diacrylate (manufactured by Aldrich, average molecular weight 250) as a crosslinking agent to a concentration of 0.61 volume% (25 mol% relative to hydroxypropyl acrylate), and polyethylene glycol diacrylate (manufactured by Aldrich, average molecular weight 550) to a concentration of 1.36 volume% (25 mol% relative to hydroxypropyl acrylate). A PVDF membrane was prepared in the same manner as Comparative Example 1, and a hydrophilization treatment was performed to produce a hydrophilic membrane.

[0060]

[0061] <Comparative Example 3>

[0062] A reaction solution was prepared under the same conditions as Comparative Example 1, except that hydroxypropyl acrylate was dissolved in a 25 volume% aqueous solution of 3-butanol to a concentration of 1.1 volume% and poly(ethylene glycol dimethacrylate) (manufactured by Aldrich, average molecular weight 250), a crosslinking agent, was dissolved in a concentration of 0.61 volume%. A PVDF membrane was prepared in the same manner as Comparative Example 1, and a hydrophilization treatment was performed to produce a hydrophilic membrane.

[0063]

[0064] <Test Example>

[0065] The method for evaluating the performance of the membranes prepared in the examples and comparative examples is as follows. The results of the performance evaluation are shown in Tables 1 to 3 below.

[0066]

[0067] (1) amount of water

[0068] The permeation rate of pure water at a temperature of 25°C was measured by constant pressure dead-end filtration, and the permeability was calculated using the following formula from the membrane area, filtration pressure (3 bar), and filtration time. In the case of a hydrophobic membrane, the permeability was measured after pre-wetting with 95% ethanol.

[0069]

[0070]

[0071] (2) Protein permeability

[0072] The permeation amount of a 0.1% BSA (Bovine Serum Albumin) aqueous solution at a temperature of 25 ℃ was measured by constant pressure dead-end filtration, and the permeability was calculated using the following formula from the membrane area, filtration pressure (3 bar), and filtration time.

[0073]

[0074]

[0075] (3) Measurement of the contact angle of the membrane

[0076] The retraction contact angle of the membrane with respect to water was measured using a dynamic contact angle measuring instrument (DCAT 11 manufactured by Data Physics Instruments GmbH) with sterile water for injection (manufactured by Otsuka Seiyaku Co., Ltd., Japan Pharmacopoeia). A hollow fiber membrane was cut to a length of approximately 2 cm and mounted on the device. The retraction contact angle was measured using the principle of the Wilhelmi method. During measurement, the motor speed was 0.10 mm / sec, the immersion depth was 10 mm, and five cycles of measurement were performed with the advance and retraction counted as one cycle. The average value of the values ​​obtained from the five measurements was used for the retraction contact angle.

[0077]

[0078] (4) Measurement of virus removal rate

[0079] In this invention, the following experiment was conducted to evaluate the virus filtration efficiency (VFE).

[0080] A solution containing bacteriophages was prepared, and a virus suspension of a certain concentration was prepared using it. Subsequently, a test filter was installed in a filtration device, and the system was configured so that the bacteriophage suspension could pass through the filter under a constant pressure (3 bar). To evaluate the efficacy of the filter, phiX174 bacteriophages with a diameter of approximately 22–27 nm and an icosahedral structure without an outer envelope were used. Due to its very small size, phiX174 is widely used as a model virus suitable for evaluating filter performance.

[0081] During the process of injecting the virus suspension into a filtration device and passing it through the filter, the filter removes virus particles. After collecting the filtered sample (outlet sample) and the undiluted solution before filtration (inlet sample), the filtration performance of the filter was evaluated by comparing the virus concentrations of the two samples. Virus concentration was quantitatively measured using the plaque formation assay to confirm the virus filtration rate of the filter, and the bacteriophage removal rate was measured using the following formula.

[0082]

[0083]

[0084] (5) Water permeability deviation

[0085] The deviation in water permeability was measured using the following formula.

[0086] (J at 3bar - J at 1bar ) / J at 3bar X 100

[0087] J at 3bar : At 3 bar for the first 5 minutes Water permeability

[0088] J at 1bar : Water permeability at 1 bar after 1 hour of transmission

[0089]

[0090] (6) Durability against organic solvents (alcohols)

[0091] The initial water permeability of the membranes of Examples 1 to 3 was measured, and the water permeability after 30 days of immersion in a 99% ethanol solution at 50 degrees was measured to confirm the durability against organic solvents (alcohols).

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098] Through Tables 1 and 2 above, it can be seen that the membrane according to the embodiment of the present invention, compared to the comparative example, maintains a maximum pore size of the hydrophilic membrane similar to that of the hydrophobic membrane despite having a low hydrophilic layer graft rate, exhibits excellent water permeability and protein permeability, and shows low swelling. In the case of the comparative example, it was confirmed that there was a very severe decrease in water permeability and protein permeability compared to the hydrophobic membrane. This is because the excessive input of the hydrophilization modifying material caused the formation of a cross-linked layer, which blocked the pores. Additionally, through Table 3, it can be seen that the membrane according to the present invention has excellent durability against organic solvents (alcohols).

[0099]

[0100] Foregoing, specific parts of the present invention have been described in detail. It will be apparent to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention. Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

[0101] The hydrophilic microporous membrane for virus filtration manufactured by the manufacturing method according to the present invention exhibits superior water permeability and protein permeability compared to conventional technology. Therefore, the manufacturing process according to the present invention and the microporous membrane manufactured by it can be utilized in various industrial fields such as water treatment, pharmaceuticals, and biomedicine.

[0102]

[0103] The present invention was carried out under the support of the Ministry of Trade, Industry and Energy of the Republic of Korea under project number 1415185455 and project number 20010846, the management agency for the said project is the Korea Institute of Planning and Evaluation for Industrial Technology, the research project name is “Development of Materials and Components Technology”, and the research project name is “Development of Nanofiltration-grade Biofiltration Module for Virus Removal”.

Claims

A method for manufacturing a hydrophilic microporous membrane for virus filtration, comprising: a reaction solution for hydrophilization treatment containing less than 3 volume% of a hydrophilic vinyl monomer having 1.1 vinyl groups relative to the total volume of the reaction solution; and a step of performing hydrophilization treatment by grafting by contacting a polyvinylidene fluoride (PVDF) microporous membrane and maintaining it for at least 12 hours. The above reaction solution for hydrophilization treatment does not contain a crosslinking agent, Method for manufacturing a hydrophilic microporous membrane for virus filtration.

2. In Paragraph 1, A method for manufacturing in which the hydrophilic vinyl monomer having one vinyl group is hydroxypropyl acrylate or hydroxybutyl acrylate.

3. In Paragraph 1, A method for manufacturing in which the hydrophilic vinyl monomer having one vinyl group is 0.01 to 2 volume% with respect to the total volume of the reaction solution.

4. In Paragraph 1, A manufacturing method in which the above reaction solution is prepared by nitrogen bubbling treatment for less than 60 minutes at a temperature of 20 degrees or lower.

5. In Paragraph 1, A manufacturing method comprising contacting the PVDF with the above reaction solution and maintaining it for 12 to 24 hours to perform a hydrophilization treatment.

6. In Paragraph 1, A manufacturing method comprising contacting the PVDF with the above reaction solution and performing a hydrophilization treatment at a temperature of 20 degrees or lower.

7. In Paragraph 1, A method for manufacturing in which the water permeability of the hydrophilic microporous membrane after the above hydrophilization treatment step is 50 LMH / bar or higher.

8. In Paragraph 1, A manufacturing method in which, after the above hydrophilization treatment step, the graft rate of the hydrophilic layer is less than 3.5%.

9. In Paragraph 1, A manufacturing method in which, after the above hydrophilization treatment step, the deviation in water permeability is less than 4%.

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