KR20140113113A - Positive charged poly(vinylidene fluoride) porous membranes and manufacturing method thereof - Google Patents

Abstract

The present invention relates to positively charged poly(vinylidene fluoride) porous membranes and a manufacturing method thereof, and more particularly, to positively charged poly(vinylidene fluoride) porous membranes, which are formed through an intensive electrostatic interaction between negative charge and cationic polyelectrolyte through oxidation and thus have a significantly low elution property. In addition, the membranes have surface positive charge in various hydrogen-ion concentration ranges, and thus, have a low protein adsorption rate and a high protein recovery rate, and a treatment flow rate of the membranes is increased through an after-treatment for significantly improving permeability. Thus, a filter replacement cycle is improved to save production costs and operating costs of a filter process used in the fields of pharmacy and medicine, so that the membranes are useful to pharmaceutical, medical, and biosimilar filter processes.

Description

TECHNICAL FIELD [0001] The present invention relates to a positively charged polyvinylidene fluoride porous separator,

The present invention relates to a positively charged polyvinylidene fluoride porous membrane and a method for producing the same. More specifically, the present invention relates to a positively charged polyvinylidene fluoride membrane and a method for producing the same, Vinylidene porous separator and a method for producing the same.

The separation, purification and recovery of specific proteins from protein culture media, etc., in the fields of general pharmaceuticals, medicine, and especially biosimilars, are known as important technical fields with great commercial value. In order to separate, purify, and recover a specific protein, it is essential to remove intracellular toxic substances such as viruses and endotoxins existing in a mixed solution such as a culture solution under a condition of a specific hydrogen ion concentration (pH) The method is to use a porous filter material that is positively charged.

For example, conventional U.S. Patent Nos. 4673504 and 4906374 disclose a filter material having a positive charge by using a nylon-based polymer, an acrylic-based monomer and an amine-based monomer, and a manufacturing method thereof. However, the above method has a problem that the cation concentration is low due to the bonding with the monomer, and thus the protein adsorption ratio is high and the hydrophobic filter media is not used.

Meanwhile, as another research and development, there has been disclosed a production example of a positively charged porous separator by mixing a polyethersulfone polymer with a hydrophilic additive such as polyvinylpyrrolidone or polyethyleneglycol, cross-linking with polyethyleneimine-epichlorohydrin, and post- . However, the above-mentioned method also has a problem in that the hydrophilic additives PVP and PEG can not be dissolved elsewhere over a long period of time after the preparation of the membrane, and even if there is no problem with the elution property, the permeability decreases due to the reduction of pores due to crosslinking of the polymer.

On the other hand, an example has been disclosed in which a PES polymer and polyglycidylether and polyamine, which are additives, are mixed to prepare a membrane, followed by cross-linking heat treatment to produce a cationic membrane. However, this method also has the disadvantage of decomposing polyamine by heat treatment and also low cation concentration.

On the other hand, a method of preparing a membrane having a positive charge through polymerization or coating of a monomer adsorbed on a surface of a polyvinylidene fluoride polymer membrane after irradiating gamma rays or an electron beam onto the surface of the membrane, Lt; / RTI > However, the above method has a disadvantage in that the manufacturing process is complicated and the manufacturing cost is increased.

As described above, when the porous separator is manufactured through the coating or crosslinking method, the porosity decreases due to the hydrophilic coating and the pore size decreases due to the swelling of the hydrophilic polymer. It is disadvantageous in that the permeability is lowered or the crosslinking efficiency is low and the protein recovery rate is decreased. If the positively charged porous membrane is prepared by pretreatment of the polymer before the membrane production using the gamma ray or electron beam, And there arises a problem that the manufacturing cost is also increased.

Disclosure of the Invention The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide a biosimilar process which has a low protein adsorption rate and a high protein recovery rate, It is an object of the present invention to provide a positive charge polyvinylidene fluoride porous separator which can be used but is simple in manufacturing process and low in manufacturing cost.

In order to solve the above-described problems,

(1) preparing a polyvinylidene fluoride separation membrane; (2) oxidizing the polyvinylidene fluoride separator prepared above; (3) immersing the oxidized separator in a solution containing a cationic polyelectrolyte to form a cationic polyelectrolyte coating layer on the surface of the oxidized polyvinylidene fluoride separator; And (4) immersing the separation membrane having the coating layer formed thereon in an acyl halide solution to form an amide layer having an amide group on the surface of the cationic polymer electrolyte coating layer. ≪ / RTI >

According to a preferred embodiment of the present invention, after the step (4), (5) the step of heat-treating may be further included.

According to a preferred embodiment of the present invention, the polyvinylidene fluoride-based polymer may include at least one selected from the group consisting of PVDF homopolymer, PVDF-HFP copolymer and PVDF-CTFE copolymer.

According to another preferred embodiment of the present invention, the step (2) may oxidize the polyvinylidene fluoride-based membrane by reacting the polyvinylidene fluoride-based membrane in a mixture of an alkali solution and an alcohol.

According to another preferred embodiment of the present invention, the alkali solution may include at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide (NaOH), and potassium permanganate (KMnO ₄ ).

According to another preferred embodiment of the present invention, the cationic polyelectrolyte of step (3) may be any one or more of polyarylamine or polyethyleneimine.

According to another preferred embodiment of the present invention, the solution containing the cationic polyelectrolyte of the step (3) may contain 2 to 20% by weight of the cationic polymer electrolyte.

According to another preferred embodiment of the present invention, the acyl halide solution of step (4) is selected from the group consisting of epichlorohydrine, acetyl chloride, isophthaloyl dichloride, terephthaloyl di Terephthaloyl dichloride and trimethoyl chloride may be contained in an amount of 0.1 to 5% by weight.

According to another preferred embodiment of the present invention, the heat treatment may be performed at 80 to 150 ° C for 30 minutes to 2 hours.

The present invention also relates to an oxidized polyvinylidene fluoride polymer layer; A cationic polyelectrolyte coating layer formed by crosslinking on the surface of the oxidized polyvinylidene fluoride polymer layer; And an amide layer formed by amide bonding to the surface of the cationic polyelectrolyte coating layer. The present invention also provides a positive electrode polyvinylidene fluoride separator.

According to a preferred embodiment of the present invention, the polyvinylidene fluoride-based polymer may include at least one selected from the group consisting of PVDF homopolymer, PVDF-HFP copolymer and PVDF-CTFE copolymer.

According to another preferred embodiment of the present invention, the amide layer may include at least one selected from the group consisting of a glycidyl group, an acetyl group, and an aryl group.

According to another preferred embodiment of the present invention, the polyvinylidene fluoride polymer layer may have a thickness of 50 to 200 μm and the cationic polymer electrolyte coating layer may have a thickness of 0.1 to 10 μm.

According to another preferred embodiment of the present invention, the thickness of the amide layer may be 0.005 to 0.1 mu m.

According to another preferred embodiment of the present invention, the positively charged polyvinylidene porous separator may have a zeta potential of 18 to 40 mV at pH 4.

According to another preferred embodiment of the present invention, the positively charged polyvinylidene porous separator may have a zeta potential of 10 to 40 mV at pH 7.

According to another preferred embodiment of the present invention, the positively charged polyvinylidene porous separator may have a zeta potential of 0 to 15 mV at a pH of 10.

According to another preferred embodiment of the present invention, the positively charged polyvinylidene porous separator has a permeability of 80 (L / m ² hr) or more and a BSA adsorption amount of 0 (μg / cm ² ) Lt; / RTI >

The positively charged polyvinylidene porous separator of the present invention is formed through strong electrostatic interactions between the negative charge through the oxidation of the surface of the separator and the cationic polyelectrolyte and thus the elution is remarkably low. Can provide low protein adsorption rates and high protein recovery rates, which are particularly useful for pharmaceutical, pharmaceutical and biosimilar filter processes. In addition, the post-treatment to improve the permeability degradation significantly improves the permeability to increase the treatment flow rate, thus shortening the filter replacement cycle, thereby reducing the production cost and operating cost of the filter process used in pharmaceutical and medical applications have.

Furthermore, the positively charged polyvinylidene porous separator membrane of the present invention can significantly improve the problem of membrane contamination such as biofouling represented by protein adsorption, and can be used as a secondary or tertiary solution in sewage treatment plants such as drinking water, Treatment and solid-liquid separation in a septic tank, it is possible to perform a long-term water treatment operation, and production cost can be reduced.

1A is a micrograph showing the surface structure of a non-oxidized PVDF separation membrane.
FIG. 1B is a micrograph showing the surface structure of the oxidized PVDF separation membrane.
FIGS. 1C to 1E are microphotographs showing the surface structure of a separator obtained by coating polyethylene oxide (PEI) on the oxidized PVDF separation membrane at different concentrations and then improving the permeability by binding epichlorohydrin (ECH).
FIG. 2 is a graph showing the zeta potential of a separation membrane coated with a non-oxidized PVDF membrane, a surface oxidized PVDF membrane, and a surface oxidized PVDF membrane at different concentrations of polyethyleneimine (PEI).
FIG. 3 is a graph showing the zeta potential of a separation membrane comprising epichlorohydrin (ECH) after coating the surface oxidized PVDF separation membrane with different concentrations of polyethyleneimine (PEI).
FIG. 4 is a graph showing the zeta potential of a separation membrane in which trimethonyl chloride (TMC) is bonded after coating the oxidized PVDF separation membrane with different concentrations of polyethyleneimine (PEI).

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings.

As described above, the conventional porous filter media having a positive charge has a disadvantage in that the porosity decreases due to the hydrophilic coating and the pore size decreases due to the swelling of the hydrophilic polymer, resulting in lower permeability or lower crosslinking efficiency, Also, if a positively charged porous separator is prepared by pretreating a polymer by using a gamma ray or an electron beam before the production of a membrane, there is a problem in that the manufacturing process is complicated and there is a problem in continuous production, resulting in an increase in manufacturing cost.

Accordingly, the present invention provides a method for producing a polyvinylidene fluoride separator, comprising: (1) preparing a polyvinylidene fluoride separator; (2) oxidizing the polyvinylidene fluoride separator prepared above; (3) immersing the oxidized separator in a solution containing a cationic polyelectrolyte to form a cationic polyelectrolyte coating layer on the surface of the oxidized polyvinylidene fluoride separator; And (4) immersing the separation membrane having the coating layer formed thereon in an acyl halide solution to form an amide layer having an amide group on the surface of the cationic polymer electrolyte coating layer. Method to solve the above-mentioned problem.

As a result, it is possible to provide a positively charged polyvinylidene fluoride separator having characteristics of showing a low protein adsorption rate and a high protein recovery rate and having a high water permeability by having a surface positive charge under various hydrogen ion concentration ranges.

 Specifically, step (1) produces a polyvinylidene fluoride separator.

 In order to prepare a polyvinylidene fluoride separation membrane, a polymer solution containing a polyvinylidene fluoride polymer and a solvent can be prepared. The polyvinylidene fluoride polymer used in the preparation of the separator may be a polyvinylidene fluoride (PVDF) homopolymer, a polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) copolymer or a polyvinylidene fluoride- chlorotrifluoro ethylene), etc. In the case of the copolymer, PVDF is preferably 50 mol% or more.

The polyvinylidene fluoride polymer to be used preferably has a weight average molecular weight of 200,000 to 1,000,000. If the molecular weight of the polyvinylidene fluoride polymer is lower than 200,000, the mechanical strength after the film formation is lowered. If the molecular weight is more than 1 million, the film formation may be difficult due to the viscosity increase.

The solvent constituting the polymer solution is not particularly limited as long as it can uniformly dissolve the polymer to prepare a separation membrane. More preferably, the solvent is selected from the group consisting of N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, Amide, and the like. The composition of the polymer solution may preferably include 10 to 30% by weight of the polyvinylidene fluoride-based polymer and 70 to 90% by weight of the solvent. If the content of the polyvinylidene fluoride polymer is less than 10% by weight, the film formation is difficult and the mechanical strength is low even after the film formation. If the content exceeds 30% by weight, the permeability may decrease.

The polyvinylidene fluoride polymer solution thus prepared can be used to produce a membrane through a conventional porous membrane production process. The process for producing the porous separation membrane is not particularly limited, but preferably a separation membrane can be produced through a conventional non-solvent-derived phase separation process. The non-solvent induction phase separation process is widely used for manufacturing a separator, and is widely known through a patent application. In the present invention, an example of preparing a separator using the same will be described, but the present invention is not limited thereto and it is within the scope of the present invention to manufacture a porous separator using the polymer solution.

In the case of a flat membrane through casting, the polymer solution is cast on a non-porous substrate such as a glass substrate or a metal substrate or a porous substrate such as a nonwoven fabric, and then immersed in the coagulating solution in the non-solvent for coagulation, washing and drying A porous flat membrane can be formed. If the coagulating liquid temperature is below room temperature, there is a problem in productivity because the coagulating liquid is delayed when the coagulating liquid temperature is below room temperature. If the coagulating liquid temperature exceeds 60 ° C, There is a disadvantage in that the temperature decreases. The porous film may be prepared by washing with water to remove remaining solvent and unreacted polymer, and drying under an atmosphere at room temperature. The washing and drying time is not particularly limited, but is preferably 24 hours or more for washing and 12 hours or more for drying.

Meanwhile, when the hollow fiber membrane is coated on the porous hollow support, the polymer solution is discharged into an outer tube of a double nozzle maintained at a temperature of 60 to 60 ° C, and at the same time, 10 m / min. The hollow fiber membrane coated on the support is passed through an air gap having a length of 0 to 10 cm and then immersed in a coagulating solution composed of water at a temperature ranging from room temperature to 60 ° C or lower. A coated porous hollow fiber membrane can be produced.

Meanwhile, as another manufacturing example, the hollow fiber membrane without support is discharged from the outer tube of the double nozzle maintained at a room temperature to 60 ° C, and at the same time, the inner coagulant is injected into the inner tube of the double nozzle in an amount of 1.0 to 15 ml / min. The discharged hollow fiber membrane is precipitated in an external coagulating liquid composed of water at a temperature ranging from room temperature to 60 ° C to form a hollow fiber membrane, and then the porous hollow fiber membrane can be manufactured through the same washing and drying processes as those described above.

 Next, in step (2), the produced polyvinylidene fluoride-based membrane is oxidized.

 The prepared polyvinylidene fluoride separator can form a porous separator that is more negatively charged than the non-oxidized polyvinylidene fluoride separator through the oxidation reaction.

In order to oxidize the polyvinylidene fluoride separation membrane, the separation membrane can be immersed in a mixture of an alkali solution and an alcohol as a reaction medium and an oxidizing agent. The alcohol used as the reaction medium in the oxidation step may be methanol, ethanol, or isopropyl alcohol, or the like, and most preferably methanol. The alkali solution used in the oxidation step may be an aqueous alkaline solution containing a single or mixed form of potassium hydroxide (KOH), sodium hydroxide (NaOH) or potassium permanganate (KMnO ₄ ), and most preferably potassium hydroxide (KOH) Aqueous solution.

 On the other hand, the concentration of the oxidizing agent (KOH or the like) in the alkali solution may be appropriately considered in connection with the reaction time and the reaction temperature, and may be preferably 1 to 30% by weight. When the oxidizing agent concentration is less than 1 wt%, formation of oxides is difficult. When the oxidizing agent concentration is more than 30 wt%, mechanical strength is weakened due to denaturation of the polymer after film formation.

The weight ratio of the alcohol to the alkali solution is preferably 3: 1 to 20: 1.

Also, the reaction time for the oxidation of the polyvinylidene fluoride separation membrane is not necessarily limited, but more preferably 30 minutes to 10 hours. If the reaction time is less than 30 minutes, the anion concentration on the surface of the membrane is low, and if it exceeds 10 hours, the mechanical strength is decreased. The negatively charged surface oxidized polyvinylidene porous separator membrane thus prepared can be cleaned with alcohol or the like and then dried for 1 to 3 hours under an atmosphere of 60 to 90 ° C.

 Next, in step (3), the oxidized separator is immersed in a solution containing a cationic polymer electrolyte to coat the cationic polymer electrolyte.

 The surface of the oxidized polyvinylidene fluoride separation membrane is more negatively charged than the non - oxidized polyvinylidene fluoride separation membrane and can bind to the cationic polyelectrolyte through strong electrostatic interaction to significantly reduce the elution of the cationic material. If the non-oxidized polyvinylidene fluoride separation membrane is coated with a cationic polymer electrolyte, the bonding force is weakened, and the polymer electrolyte is eluted at the time of water permeation, so that the positive charge intensity is decreased and protein adsorption may occur.

In addition, the present invention can remarkably lower the protein adsorption rate by forming a cationic polymer electrolyte coating layer on the surface of the separation membrane to produce a separation membrane having a positive charge. If the polyvinylidene oxide separation membrane is not coated with a cationic polymer electrolyte, the porous separation membrane becomes negatively charged and it is difficult to remove intracellular toxic substances such as endotoxin generated during protein culture. Therefore, a biosimilar It is not suitable for the process.

In order to coat the cationic polymer electrolyte, the oxidized separator may be immersed in the cationic polymer electrolyte solution. The cationic polymer electrolyte may be at least one selected from the group consisting of polyallylamine and polyethyleneimine, and more preferably polyethyleneimine. Further, the solvent of the cationic polyelectrolyte solution is not particularly limited as long as it dissolves the cationic polyelectrolyte, but it may preferably be water. The concentration of the cationic polyelectrolyte depends on the surface anion concentration of the oxidized polyvinylidene chloride separator But it is preferably 2 to 20% by weight in the present invention. If the concentration of the cationic polymer electrolyte is less than 2% by weight, the cation concentration is low and the protein adsorption rate is high. If the concentration exceeds 20% by weight, unreacted cationic polymer electrolyte is generated, which is not efficient. The immersion time is preferably 30 minutes to 5 hours. If the immersion time is less than 30 minutes, the cation concentration is low. If the immersion time exceeds 5 hours, productivity may be a problem. After immersing in the cationic polyelectrolyte solution, the separator may be washed several times with alcohol or the like, and then dried in an oven at 60 to 90 ° C for 1 to 3 hours.

Next, in step (4), the separation membrane having the coating layer formed thereon is immersed in an acyl halide solution to form an amide layer having an amide group on the surface of the cationic polymer electrolyte coating layer.

As described above, the separator coated with the cationic polymer electrolyte exhibits low permeability due to pore reduction due to coating and swelling with water when measuring permeability. Accordingly, the present invention provides an amide layer having an amide bond on the surface of a cationic polyelectrolyte coating layer by reaction between an amine group and an acyl halide group remaining on the surface of a separator coated with a cationic polyelectrolyte, And the water permeability was remarkably improved. Therefore, the positively charged polyvinylidene porous separator of the present invention has excellent positive charge and significantly improved water permeability, and thus can be usefully used in pharmaceutical, pharmaceutical, and biosimilar filter processes.

Specifically, the separation membrane coated with the cationic polyelectrolyte is immersed in an acyl halide solution, and the acyl halide solution may include epichlorohydrine, acetyl chloride, isophthaloyl dichloride, May include monomers in the form of terephthaloyl dichloride or trimethoyl chloride, or the like, and most preferably may contain epichlorohydrine-based monomer (s) . The solvent of the halide solution is not particularly limited as long as it can dissolve the monomers uniformly, but hexane may be preferably used. The concentration of the monomers in the halide solution is preferably 0.1 to 5% by weight. If the concentration of the monomer is less than 0.1% or exceeds 5% by weight, the improvement in the water permeability is insignificant. The immersion time is not particularly limited, but it is more preferable to immerse for 5 minutes to 1 hour in consideration of water permeability improvement and productivity.

Finally, step (5) may heat treat the separator.

After immersing in an acyl halide solution, the separator can be washed, followed by heat treatment to promote amide bond formation, thereby inhibiting dissolution of the cationic polymer electrolyte and increasing porosity and permeability .

The heat treatment may be performed at 80 to 150 ° C for 30 minutes to 2 hours. If the heat treatment temperature is lower than 80 ° C, the amide reaction is slow or the amide bond does not sufficiently occur. If the temperature exceeds 150 ° C, decomposition of the cationic polyelectrolyte may be induced. If the heat treatment time is less than 30 minutes, the amide bond is not sufficient. If the heat treatment time is more than 2 hours, the effect of improving the water permeability is insignificant or the productivity is greatly deteriorated.

 In addition, the positively charged polyvinylidene-based porous separator of the present invention produced as described above comprises an oxidized polyvinylidene fluoride polymer layer; A cationic polyelectrolyte coating layer formed by crosslinking on the surface of the oxidized polyvinylidene fluoride polymer layer; And an amide layer formed by amide bonding to the surface of the cationic polyelectrolyte coating layer.

The positive-acting polyvinylidene-based porous separator of the present invention is characterized in that the polyvinylidene fluoride polymer layer, which is more negatively charged than the non-oxidized polyvinylidene fluoride polymer layer, is crosslinked through strong electrostatic interaction with the polyvinylidene fluoride polymer layer The elution of the cationic substance can be remarkably lowered. If the non-oxidized polyvinylidene fluoride polymer layer is coated with a cationic polymer electrolyte, the bonding force is weakened, and the polymer electrolyte is eluted at the time of water permeation, so that the positive charge intensity is decreased and protein adsorption may occur.

In addition, when the porous separator contains only the polyvinylidene oxide polymer layer and is not coated with the cationic polymer electrolyte, the porous separator is negatively charged, and it is difficult to remove intracellular toxic substances such as endotoxin generated during protein culture, It is not suitable for the biosimilar process.

On the other hand, the positively charged polyvinylidene porous separator of the present invention has a good positive charge, thereby remarkably lowering the protein adsorption rate. However, due to the reaction between the amine group and the acyl halide group remaining on the surface of the separator coated with the cationic polyelectrolyte, By forming an amide layer having an amide bond on the surface of the electrolyte coating layer, the pore enlargement and the swelling phenomenon occurring upon contact with water are significantly suppressed, and the permeability can be remarkably improved.

 The positively charged polyvinylidene porous separator of the present invention may be a flat membrane or a hollow fiber membrane. The thickness of the polyvinylidene fluoride polymer layer may be 50-200 탆, and the thickness of the cationic polymer electrolyte coating layer may be 0.1-10 탆. When the thickness of the cationic polyelectrolyte coating layer is less than 0.1 m, the positivity decreases and the protein adsorption rate increases. When the thickness exceeds 10 m, the permeability decreases.

In addition, the amide layer of the positive charge polyvinylidene fluoride separator of the present invention may contain a single or mixed type of glycidyl group, acetyl group or aryl group, The thickness of the layer may be from 0.005 to 0.1 mu m. When the thickness of the amide layer is less than 0.005 占 퐉 or more than 0.1 占 퐉, the effect of improving the water permeability is insignificant.

The positively charged polyvinylidene porous separator of the present invention can exhibit a low protein adsorption rate and a high protein recovery rate by having a positive charge under various hydrogen ion concentration ranges. Specifically, the positively charged polyvinylidene fluoride porous separator may have a zeta potential of 18 to 40 mV at pH 4, a zeta potential of 10 to 40 mV at pH 7, and a zeta potential of 0 to 15 mV at pH 10 .

FIG. 3 shows the zeta potential of a membrane obtained by coating a surface-oxidized PVDF membrane with polyethyleneimine (PEI) at different concentrations (5, 7, and 10 wt%, respectively) and then with epichlorohydrin (ECH). When 5 wt% polyethyleneimine (PEI) was coated, the zeta potentials were all satisfied at pH 4, 7, and 10, except that they had a slight negative charge at pH 10, Surface positive charge can be confirmed.

Further, positive charge property polyvinyl fluoride dengye porous separator of the present invention is also pitching also is significantly improved at the same time, indicating a 0 (μg / cm ²⁾ the amount of BSA adsorbed at pH 4.8 and satisfies the positive features 80 (L / m ² hr) or higher.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

≪ Example 1 >

100 g of PVDF homopolymer (Solvay 1015, Mw: 570,000) was added to a flask containing 400 g of NMP (N-methyl pyrrolidone, DAEJUNG) as a solvent. Thereafter, the temperature of the solution was maintained at 65 ° C, and the solution was stirred at rpm 200 for 2 hours to prepare a homogeneous polymer solution. A part of the prepared solution was poured on a substrate of a normal temperature, and the film was formed to a thickness of 200 μm by using a casting knife, and then washed for 24 hours in flowing tap water at room temperature. Thereafter, the membrane was dried in an oven at 80 ° C for 24 hours to prepare a porous PVDF membrane.

In order to oxidize the PVDF separation membrane, the PVDF separation membrane specimen was immersed in a solution of 1000 g of methanol and 100 g of a 5 wt% potassium hydroxide (KOH) aqueous solution for 4 hours. Thereafter, the membrane was washed three times with methanol maintained at 0 ° C and dried in an oven at 80 ° C for 2 hours to prepare a surface oxidized PVDF porous separator.

Thereafter, 17 g of a 30 wt% polyethyleneimine (PEI) aqueous solution (Mn 70,000, Wako) and 83 g of distilled water were mixed to prepare a uniform aqueous solution of a cationic polyelectrolyte having a polyethyleneimine concentration of 5.1 wt%. Then, the surface-oxidized PVDF porous membrane was immersed in the aqueous solution for 2 hours, washed several times with methanol, and then dried in an oven at 80 ° C for 2 hours. On the other hand, 5 g of epichlorohydrin (ECH) (Daejung) and 995 g of hexane were mixed to prepare a 0.5 wt% epichlorohydrin (ECH) solution. The dried separator specimens were immersed in an epichlorohydrin solution for 30 minutes, and then heat-treated at 120 ° C oven for 1 hour, washed several times with methanol, and then dried in an oven at 80 ° C for 2 hours to obtain a positively charged poly A vinylidene fluoride porous separator was produced.

≪ Example 2 >

Except that 23 g of a 30 wt% polyethyleneimine (PEI) aqueous solution (Mn 70,000, Wako) and 77 g of distilled water were mixed to immerse the surface oxidized PVDF porous separation membrane in a polyethyleneimine (PEI) aqueous solution having a concentration of 6.9 wt% . ≪ / RTI >

≪ Example 3 >

Except that 33 g of a 30 wt% polyethyleneimine (PEI) aqueous solution (Mn 70,000, Wako) and 67 g of distilled water were mixed to immerse the surface oxidized PVDF porous separation membrane in a polyethyleneimine (PEI) aqueous solution having a concentration of 9.9 wt% . ≪ / RTI >

<Example 4>

5 g of trimethoyl chloride (TMC) (Aldrich) was mixed with 995 g of hexane in place of epichlorohydrin to prepare a 0.5 wt% trimethoyl chloride (TMC) solution, and then a PEI coated membrane Was prepared in the same manner as in Example 1, except that it was immersed.

&Lt; Example 5 >

Except that 23 g of a 30 wt% polyethyleneimine (PEI) aqueous solution (Mn 70,000, Wako) and 77 g of distilled water were mixed to immerse the surface oxidized PVDF porous separation membrane in a polyethyleneimine (PEI) aqueous solution having a concentration of 6.9 wt% . &Lt; / RTI &gt;

&Lt; Example 6 >

Except that 33 g of a 30 wt% polyethyleneimine (PEI) aqueous solution (Mn 70,000, Wako) and 67 g of distilled water were mixed to immerse the surface oxidized PVDF porous separation membrane in a polyethyleneimine (PEI) aqueous solution having a concentration of 9.9 wt% . &Lt; / RTI &gt;

&Lt; Comparative Example 1 &

100 g of PVDF homopolymer (Solvay 1015, Mw: 570,000) was added to a flask containing 400 g of NMP (N-methyl pyrrolidone, DAEJUNG) as a solvent. Thereafter, the temperature of the solution was maintained at 65 ° C, and the solution was stirred at rpm 200 for 2 hours to prepare a homogeneous polymer solution. A part of the prepared solution was poured on a substrate of a normal temperature, and the film was formed to a thickness of 200 μm by using a casting knife, and then washed for 24 hours in flowing tap water at room temperature. Thereafter, the membrane was dried in an oven at 80 ° C for 24 hours to prepare a porous PVDF membrane.

&Lt; Comparative Examples 2 to 4 >

Except that the Epichlorohydrin solution, the TMC solution immersion and the heat treatment were not performed after immersion, washing and drying in a polyethyleneimine (PEI) aqueous solution to form a positively chargeable coating layer.

<Experimental Example>

1. Measurement of permeability

For the permeability evaluation, the membrane specimens were pre-immersed in 30% ethanol solution for 10 minutes and then continuously immersed in distilled water for 30 minutes. The unit membrane area (m ² ), the unit time (hr), and the unit pressure (bar) were measured after the pure water at room temperature was pressurized under a constant pressure of 1 atm and the amount of water filtered for 60 minutes in the dead- And converted into the amount (L) of water to be filtered.

The results of permeability measurement of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1.

2. Observation of morphology

An electron scanning microscope (SNE-3000M, SEC) was used to observe the microstructure of the membrane surface. Membrane specimens were prepared by cutting in liquid nitrogen and the surface of the sample after Au deposition was measured.

1A to 1E were prepared in the same manner as in Example 1 except that the concentrations of polyethyleneimine (PEI) were varied (5, 7, and 10 wt%, respectively) in the non-oxidized PVDF membrane, the surface oxidized PVDF membrane, and the surface oxidized PVDF membrane, A micrograph showing the surface structure of the separation membrane improved in the figure. As can be seen from FIGS. 1A to 1E, no significant change was observed between the film surfaces of the non-oxidized PVDF membrane and the other modified PVDF membrane.

3. Measurement of contact angle

The contact angle (CAM DSA100S2, Germany) was attached to the holder and the droplet was dropped on the surface of the membrane to observe the drop of water drop for 20 seconds. Respectively. The contact angle was measured after three measurements with different surface positions and then averaged.

The contact angle measurement results of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1.

4. Measurement of surface charge (zeta-potential)

For the measurement of Zeta potential (Anton Paar KG, Graz, Austria), a 1 cm x 2 cm membrane sample was inserted into a holder and the electrical conductivity was adjusted to 127.8 mS / m using a KCl solution at 20 ° C. After the pH was adjusted to 4.8 using 0.1 M HCl and 0.1 M NaOH aqueous solution, the Zeta potential of the membrane was measured.

FIG. 2 shows the zeta potentials of the membranes coated with different concentrations of polyethyleneimine (PEI) on the non-oxidized PVDF membrane, the surface oxidized PVDF membrane and the surface oxidized PVDF membrane, respectively (5, 7, and 10 wt%, respectively). As can be seen from FIG. 2, the non-oxidized PVDF membrane has a very narrow range of surface charge within the range of pH 4 to 10, while the PVDF membrane oxidized with potassium hydroxide (KOH) 10, the anion characteristics are very strong compared to the non-oxidized PVDF membranes. On the other hand, in the case of the membrane coated with polyethyleneimine (PEI) on the oxidized PVDF membrane, it is confirmed that the membrane has a strong positive charge as the concentration of polyethyleneimine (PEI) increases and has a complete surface positive charge within the range of pH 4 to 10 .

FIG. 3 is a graph showing the zeta potential of a PVDF membrane improved in permeability by binding epichlorohydrin (ECH). It shows a slight negative charge at pH 10 when 5 wt% polyethyleneimine (PEI) It can be confirmed that all the surface positive charges are all within the range of pH 4 to 10 except for the band. These results show that ECH treatment and heat treatment have little effect on the film surface charge.

4 is a graph showing the results of zeta potential of PVDF membranes improved in water permeability by binding trimethonyl chloride (TMC). As in the case of binding epichlorohydrin (ECH), 5 wt% polyethyleneimine PEI) has a complete surface positive charge within the range of pH 4 to 10, except that it has a slight negative charge at pH 10. These results show that TMC treatment and heat treatment have little effect on the film surface charge.

5. Measurement of adsorption amount of BSA (Bovine Serum Albumin) at pH 4.8

BSA was dissolved in pure water at room temperature at 0.1 wt% under hydrogen ion concentration of 4.8, which is the isoelectric point of BSA (Bovine Serum Albumin, Aldrich, MW 66,000). Then, 6 membrane samples of the same composition with a membrane area of 4 cm ² were prepared and the weight of the three membranes was measured and averaged. On the other hand, a certain amount of BSA solution was dropped on the surface of the remaining three membranes, followed by drying at 80 ° C for 2 hours. The dried membrane was washed three times with an aqueous solution of pH 4.8, dried at 80 ° C for 2 hours, and weighed. The average BSA adsorption amount was calculated using the following equation.

Average adsorption amount (μg / cm ² ) = (separation membrane weight after adsorption - separation membrane weight before adsorption) / membrane area

Table 2 shows the BSA adsorption amount measurement results of Examples 1 to 6 and Comparative Examples 1 to 4.

division PVDF
weight% NMP
weight% PEI  density
(weight%) Acyl halide
Kinds Pitcher
(L / m ²  h bar ) Contact angle (°) Comparative Example 1 20 80 - - 129 83 Comparative Example 2 20 80 5.1 - 36 74 Comparative Example 3 20 80 6.9 - 18 55 Comparative Example 4 20 80 9.9 - 16 43 Example 1 20 80 5.1 ECH 88 66 Example 2 20 80 6.9 ECH 109 58 Example 3 20 80 9.9 ECH 127 47 Example 4 20 80 5.1 TMC 88 65 Example 5 20 80 6.9 TMC 79 53 Example 6 20 80 9.9 TMC 60 52

As can be seen from Table 1, in Comparative Examples 2 and 4 coated with polyethyleneimine (PEI), the permeability decreased sharply as the concentration of PEI increased, indicating that the polyethyleneimine, a hydrophilic electrolyte, And can be explained in connection with the behavior in which permeation of water is bubbled by water and the membrane pores gradually decrease. On the other hand, in Examples 1 to 3 which were subjected to the reaction heat treatment with epichlorohydrine to improve the water permeability, the permeability was remarkably improved compared with that before the epichlorohydrin treatment, and in particular, the PEI concentration And the permeability increased with the increase of the permeability. These results are attributed to the fact that the pore enlargement through amide group formation through the reaction between epichlorohydrin and the chloride groups of the primary amine groups remaining on the surface of the membrane and the swelling phenomena caused by contact with water are remarkably suppressed .

On the other hand, in Examples 4 to 6 in which the reaction heat treatment with trimethoyl chloride was performed, the permeability was remarkably improved as compared with that in the case of trimesoyl chloride treatment. It is interpreted that the pore enlargement through the amide group formation through the reaction between the amine groups and the chloride groups of trimethoyl chloride and the swelling phenomena caused by contact with water are remarkably suppressed.

division PVDF
weight% NMP
weight% PEI  density
(weight%) Acyl halide
Kinds BSA
Adsorption amount ( mg / cm ² )
at pH  4.8 Comparative Example 1 20 80 - - 2.5 Comparative Example 2 20 80 5.1 - 0.13 Comparative Example 3 20 80 6.9 - 0.0 Comparative Example 4 20 80 9.9 - 0.0 Example 1 20 80 5.1 ECH 0.0 Example 2 20 80 6.9 ECH 0.0 Example 3 20 80 9.9 ECH 0.0 Example 4 20 80 5.1 TMC 0.0 Example 5 20 80 6.9 TMC 0.0 Example 6 20 80 9.9 TMC 0.0

As shown in Table 2, the BSA adsorption amount of the PVDF separation membrane (Comparative Example 1) was 2.5 (μg / cm ² ) and the BSA adsorption amount was 0.13 (μg / cm 2) ² ). On the other hand, in Comparative Examples 3 and 4 where the cation concentration was high, the BSA adsorption amount was 0 (μg / cm ² ). On the other hand, in Examples 1 to 3 in which reaction heat treatment with epichlorohydrine was performed to improve permeability and in Examples 4 to 6 in which reaction heat treatment with trimesoyl chloride was conducted, the BSA adsorption amount was 0 (μg / cm ² ) In addition, the protein recovery rate was also increased.

Claims (18)

(1) preparing a polyvinylidene fluoride separation membrane;
(2) oxidizing the polyvinylidene fluoride separator prepared above;
(3) immersing the oxidized separator in a solution containing a cationic polyelectrolyte to form a cationic polyelectrolyte coating layer on the surface of the oxidized polyvinylidene fluoride separator; And
(4) a step of immersing the separation membrane having the coating layer formed thereon in an acyl halide solution to form an amide layer having an amide group on the surface of the cationic polymer electrolyte coating layer; .
The method according to claim 1,
After the step (4)
(5) heat-treating the polyvinylidene fluoride porous separator.
The method according to claim 1,
Wherein the polyvinylidene fluoride-based polymer comprises at least one selected from the group consisting of a PVDF homopolymer, a PVDF-HFP copolymer, and a PVDF-CTFE copolymer.
The method according to claim 1,
Wherein the polyvinylidene fluoride separation membrane is oxidized by reacting the polyvinylidene fluoride separation membrane in a mixture of an alkali solution and an alcohol to thereby form a polyvinylidene fluoride separation membrane.
5. The method of claim 4,
Wherein the alkali solution comprises at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide (NaOH), and potassium permanganate (KMnO ₄ ).
The method according to claim 1,
Wherein the cationic polyelectrolyte of step (3) is at least one of polyarylamine and polyethyleneimine.
The method according to claim 1,
Wherein the solution containing the cationic polyelectrolyte of step (3) comprises 2 to 20 wt% of the cationic polymer electrolyte.
The method according to claim 1,
The acyl halide solution in step (4) may be selected from the group consisting of epichlorohydrine, acetyl chloride, isophthaloyl dichloride, terephthaloyl dichloride and trimethonyl chloride And 0.1 to 5% by weight of at least one selected from the group consisting of trimethylaluminum chloride, trimethoyl chloride, and the like.
3. The method of claim 2,
Wherein the heat treatment is performed at 80 to 150 DEG C for 30 minutes to 2 hours. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
An oxidized polyvinylidene fluoride polymer layer;
A cationic polyelectrolyte coating layer formed by crosslinking on the surface of the oxidized polyvinylidene fluoride polymer layer; And
And an amide layer formed by amide bonding on the surface of the cationic polyelectrolyte coating layer.
11. The method of claim 10,
Wherein the polyvinylidene fluoride-based polymer comprises at least one selected from the group consisting of PVDF homopolymer, PVDF-HFP copolymer, and PVDF-CTFE copolymer.
11. The method of claim 10,
Wherein the amide layer comprises at least one selected from the group consisting of a glycidyl group, an acetyl group, and an aryl group.
11. The method of claim 10,
Wherein the polyvinylidene fluoride polymer layer has a thickness of 50 to 200 占 퐉 and the cationic polyelectrolyte coating layer has a thickness of 0.1 to 10 占 퐉.
11. The method of claim 10,
Wherein the amide layer has a thickness of 0.005 to 0.1 占 퐉.
11. The method of claim 10,
Wherein the positively charged polyvinylidene fluoride porous separator has a zeta potential of 18 to 40 mV at a pH of 4.
11. The method of claim 10,
Wherein the positively charged polyvinylidene porous separator has a zeta potential of 10 to 40 mV at a pH of 7.
11. The method of claim 10,
Wherein the positively charged polyvinylidene fluoride porous separator has a zeta potential of 0 to 15 mV at a pH of 10.
11. The method of claim 10,
Wherein the positively charged polyvinylidene porous separator has a permeability of at least 80 (L / m ² hr) and a BSA adsorption amount at a pH of 4.8 of 0 (μg / cm ² ). Membrane.

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