WO2016072634A1 - Method for preparing polymer resin composition for producing filtration membrane having improved hydrophilicity and mechanical strength - Google Patents

Abstract

Disclosed are a polymer resin composition for filtration membrane production capable of improving the physical strength of a hydrophilized polymer filtration membrane, particularly a polymer resin composition for filtration membrane production which not only improves the physical strength of a hydrophilized polymer filtration membrane but also uses additives used to allow for higher hydrophilicity, and a polymer filtration membrane production method using same. The present invention provides a method for preparing a polymer resin composition for filtration membrane production and a polymer filtration membrane production method using same, the method for preparing a polymer resin composition for filtration membrane production comprising the steps of: (a) mixing a hydrophobic polymer base resin, a first solvent, and a hydrophilic organic additive so as to prepare a polymer solution; (b) preparing a hydrophilic inorganic additive in the form of a sol; and (c) adding the hydrophilic inorganic additive to the polymer solution.

Description

Manufacturing method of polymer resin composition for preparing filtration membrane with improved hydrophilicity and mechanical strength

The present invention relates to a method for preparing a polymer resin composition for preparing a filter membrane, and more particularly, to a method for preparing a polymer resin composition for preparing a filter membrane with improved hydrophilicity and mechanical strength.

The present invention is derived from research conducted as part of the Global Top Environmental Technology Development Project supported by the Ministry of Environment in 2014.

[Task No .: GT-14-B-01-002-0, Title: Development of Wastewater Recycling Process Based on Biocontamination Control Functional Membrane]

Polymer filtration membranes are used for separation of liquids or gases in various fields such as medicine, semiconductor, battery, biotechnology, dairy, beverage and food, and water treatment.

The polymer filtration membrane is an important factor that can determine the efficiency and economic efficiency of the material separation process. The polymer filtration membrane is a sintered membrane obtained by injecting and sintering polymer particles into a mold, or a crystalline polymer film or hollow fiber. Stretched film that imparts porosity, or a tracking etching film prepared by irradiating a polymer film with radiation and immersing it in an etching solution, or a heat induced phase conversion film prepared by mixing with a diluent at a temperature above the melting point of the polymer, or a polymer. Background Art A phase conversion membrane by a solvent exchange method formed by dipping a homogeneous solution containing a resin into a non-solvent is known.

At present, the solvent exchange method is mainly used to commercially manufacture the microfiltration membrane or the ultrafiltration membrane. Recently, a method of casting a polymer solution and precipitating it in a non-solvent agglomeration tank (nonsolvent induced phase separation) has been used.

On the other hand, as the porous polymer membrane, a polymer such as polysulfone, polyether sulfone, cellulose acetate, polyvinylidene fluoride and the like is usually used. Polymers, except for cellulose acetate, are hydrophobic polymers, which degrade the filtration performance and shorten the life due to accumulation of microorganisms and suspended solids. For this purpose, the hydrophilic polymer is prepared by a non-solvent induced phase transition process to increase the hydrophilicity and have a high permeation flow rate, but has a weak physical strength, and thus is easily broken or damaged, making it difficult to use in the long term. .

Korean Patent Laid-Open Publication No. 2007-0072120 discloses a hydrophilic preparation method of an asymmetric filtration membrane by adding polymethylmethacrylate as a hydrophilic additive to a hydrophobic polymer solution. Such a hydrophilization method has an advantage in that the hydrophilicity is maintained almost permanently due to excellent compatibility with the hydrophobic polymer, but the physical strength of the membrane is lowered due to the low brittleness of the hydrophilic additive polymethylmethacrylate.

International Patent Publication No. 2006/006340 relates to a method for improving the hydrophilicity of a polyvinylidene fluoride-based membrane for water treatment, comprising: polymerizing a polyvinylidene-based resin, including titanium oxide and a granular inorganic additive in a granular form. Disclosed is a technique comprising a step of preparing a solution, melt extruding the mixed composition, and extracting a solvent. However, titanium oxide, which is an inorganic additive in the form of granules, is depleted from the polyvinylidene fluoride-based membrane when it is in contact with water for a long time, so that the hydrophilic effect is not permanent. When the detached additive is mixed with the filtrate, it is not satisfied for water treatment. There is no difficulty. In addition, in the case of titanium oxide, there is a problem that the economic efficiency is low as an additive of the water treatment membrane.

Ochoa et al. (NA Ochoa et al., Journal of Membrane Science, 2003, p203-211.) Disclose a method of improving the hydrophilicity of a polyvinylidene fluoride membrane using a polymethylmethacrylate as a hydrophilic additive. There is a problem that less hydrophilic effect compared to the amount of the methyl methacrylate additive added, the mechanical strength of the membrane can be lowered.

Yu et al. (LY Yu et al., Journal of Membrane Science, 2009, p257-265.) Disclose a method for improving the hydrophilicity and physical strength of polyvinylidene fluoride hollow fiber membranes using silicon oxide as an inorganic additive. However, there is a problem in that the amount of silicon oxide added to improve the mechanical stability and hydrophilicity of the membrane is limited.

Therefore, the present invention has been made to solve the above problems, as a polymer resin composition for preparing a membrane for improving the physical strength of the hydrophilized polymer filter membrane, specifically not only to improve the physical strength of the hydrophilized polymer filter membrane, An object of the present invention is to provide a polymer resin composition for preparing a filtration membrane using an additive used to have a higher hydrophilicity and a method of preparing a polymer filtration membrane using the same.

The present invention to solve the above problems, (a) preparing a polymer solution by mixing a hydrophobic polymer base resin, a first solvent and a hydrophilic organic additive; (b) preparing a hydrophilic inorganic additive in sol form; And (c) adding the hydrophilic inorganic additive to the polymer solution.

In addition, the polymer solution is 1 to 50% by weight of the hydrophobic polymer base resin, 1 to 80% by weight of the first solvent and 0.01 to 50% by weight of the hydrophilic organic additives to provide a method for producing a polymer resin composition for manufacturing a filter membrane. do.

In addition, the hydrophobic polymer base resin is polyethersulfone (PES), polysulfone (PSf), polyther ketone (PEK), polytherserketone (PEEK), sulfonated polymer (sulfonated polymer), polyvinylidene fluoride ( PVDF), polytetrafluoroethylene (PTFE), polyvinylidene chloride (PVDC), chlorinate polyvinylchloride (CPVC), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and ethylenechlorotrifluoro It provides a polymer resin composition for producing a filtration membrane, characterized in that at least one member selected from the group consisting of ethylene (ECTFE).

In addition, the hydrophilic organic additive is polyacrylonitrile (PAN), polyethylene oxide (PEO), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polypropylene glycol (PPG) and Polyethylene oxide-polypropylene oxide block copolymer (PEO-PPO-PEO) provides a method for producing a polymer resin composition for producing a filtration membrane, characterized in that at least one member selected from the group consisting of.

In addition, the hydrophilic inorganic additive provides a method for producing a polymer resin composition for producing a filtration membrane, characterized in that added to the content of 0.1 to 10 parts by weight based on 100 parts by weight of the polymer solution.

In addition, the hydrophilic inorganic additive is characterized in that at least one member selected from the group consisting of titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO) and zirconia (ZrO ₂ ). Provided is a method for preparing a polymer resin composition for preparing a filtration membrane.

In addition, the step (b) provides a method for producing a polymer resin composition for producing a filtration membrane, characterized in that carried out by mixing the silica precursor and the second solvent.

In addition, the silica precursor is at least one member selected from the group consisting of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), trimethoxymethylsilane (MTMS) and dimethyl diethoxysilane (DMDEOS) It provides a polymer resin composition for producing a filtration membrane.

The present invention to solve the another problem, the step of applying the polymer resin composition on a substrate; And a non-solvent induced phase transition step of precipitating the applied polymer resin composition to a non-solvent.

In addition, the filtration membrane provides a method characterized in that it has a flat membrane or hollow fiber structure.

According to the present invention, a hydrophilic organic additive is mixed with a hydrophobic polymer base resin to improve hydrophilicity of the filtration membrane, as well as a hydrophilic inorganic additive in a polymer solution in which a hydrophilic organic additive is mixed with a hydrophobic polymer base resin to improve hydrophilicity and physical strength. By mixing in the form of a sol instead of the conventional granular form, the hydrophilization ability is not only improved compared to the case of adding a conventional hydrophilic organic additive, but also maintains the physical strength, even when operating the membrane for a long time It is possible to provide a method for preparing a polymer resin composition for preparing a filtration membrane and a method for producing a polymer filtration membrane using the same, which can minimize the amount of loss.

1 is a graph showing the results of X-ray diffraction analysis of the polyvinylidene fluoride film prepared according to Examples 2 and 3, Comparative Examples 1 and 2 of the present invention,

Figure 2 is a photograph showing the optical microscope measurement results of the polyvinylidene fluoride hollow fiber membrane prepared according to Example 4 and Comparative Example 3 of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, not to exclude other components, unless otherwise stated.

MEANS TO SOLVE THE PROBLEM The present inventors faced the problem that hydrophilicity and mechanical strength improvement are incompatible with each other when the polymer resin composition for manufacturing a filter membrane uses the inorganic additive added for mechanical strength improvement with the hydrophilic inorganic additive added for conventional hydrophilicity improvement. As a result of the research, it has been found that when the hydrophilic inorganic additive is added in the sol form and the hydrophilic organic additive is added to the mixed polymer solution, the hydrophilicity is further increased while maintaining the mechanical strength.

Therefore, the present invention comprises the steps of (a) preparing a polymer solution by mixing a hydrophobic polymer base resin, a first solvent and a hydrophilic organic additive; (b) preparing a hydrophilic inorganic additive in sol form; And (c) adding the hydrophilic inorganic additive to the polymer solution.

Step (a) is a step of preparing a polymer solution comprising a hydrophobic polymer base resin, the polymer base resin forms a basic skeleton of the filtration membrane prepared from the polymer resin composition to be finally prepared and is a place where pores are formed.

As the polymer base resin, a conventional polymer resin applied to a filtration membrane such as a microfiltration membrane or an ultrafiltration membrane in the art to which the present invention pertains may be applied without limitation, for example, polyether sulfone (PES), polysulfone (PSf), poly Circoketone (PEK), Polyacer Ketone (PEEK), Sulfonated polymer, Polyvinylidene fluoride (PVDF), Polytetrafluoroethylene (PTFE), Polyvinylidene chloride (PVDC), Chlorine Nate polyvinyl chloride (CPVC), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), ethylene chlorotrifluoroethylene (ECTFE) and the like can be applied, preferably polyvinylidene fluoride (PVDF) Can be applied. In this case, the polyvinylidene fluoride (PVDF) may have a weight average molecular weight of 50,000 ~ 2,000,000.

In the present invention, the polymer base resin may be included in the polymer solution of 1 to 50% by weight, preferably 5 to 40% by weight. In other words, while ensuring the mechanical properties of the polymer filtration membrane prepared using the polymer resin composition according to the present invention, in consideration of the pore shape and distribution control difficulties that may occur when excessive addition of the polymer base resin, the polymer base resin The content of is advantageously controlled in the above range.

The first solvent allows the polymer solution to have an appropriate viscosity and allows the polymer base resin to be sufficiently dissolved. These first solvents include dimethylacetamide (DMAc), dimethylformamide (DMF), N-methyl-pyrrolidinone (NMP), N-octyl-pyrrolidinone, N-phenyl-pyrrolidinone, dimethyl sulfoxide (DMSO), sulfolane, catechol, ethyl lactate, acetone, ethyl acetate, butyl carbitol, monoethanolamine, butyrolactone, diglycol amine, γ-butyrolactone, tetrahydrofuran (THF), methyl form Mate, diethyl ether, ethyl benzoate, acetonitrile, ethylene glycol, glycerol, dioxane, methyl carbitol, monoethanolamine, pyridine, propylene carbonate, toluene, decane, hexane, hexanes, xylenes, cyclohexane , 1H, 1H, 9H-perfluoro-1-nonanol, perfluoro-1,2-dimethylcyclobutane, perfluoro-1,2-dimethylcyclohexane, and perfluorohexane (s) are alone or Mixed ones may be used, preferably dimethylacetamide (DMAc), dimeth Formamide (DMF), N- methyl-pyrrolidinone (NMP), there are dimethyl sulfoxide (DMSO) or sulfolane can be used.

In the present invention, the first solvent may be included in the polymer solution 1 to 80% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight. In other words, the polymer base resin contained in the polymer solution can be sufficiently dissolved, while giving the appropriate viscosity required for the preparation of the polymer filtration membrane, and in consideration of the pore shape and distribution control difficulties that may occur when an excessive amount is added, The content of 1 solvent is advantageously adjusted in the above-mentioned range.

The hydrophilic organic additive is added for hydrophilization of the hydrophobic polymer base resin, and may include components conventional in the art to which the present invention pertains, such as polyacrylonitrile (PAN), polyethylene oxide (PEO), and polyvinyl. Acetate (PVAc), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polypropylene glycol (PPG) and polyethylene oxide-polypropylene oxide block copolymer (PEO-PPO-PEO) alone or in combination Can be used, preferably polymethylmethacrylate (PMMA) can be used.

In the present invention, the hydrophilic organic additive may be included in the polymer solution 0.01 to 50% by weight, preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight. When the hydrophilic organic additive content is less than 0.01% by weight, the degree of hydrophilization of the polymer base resin may be insufficient. When the hydrophilic organic additive content is more than 50% by weight, the mechanical strength of the manufactured filtration membrane may be reduced.

The steps (b) and (c) are steps of adding a hydrophilic inorganic additive to the polymer solution and preparing a hydrophilic inorganic additive for maintaining the physical strength of the filtration membrane added to the polymer solution and further improving the hydrophilicity. In the invention, a hydrophilic inorganic additive is prepared in the form of a sol and added to the polymer solution.

The content of the hydrophilic inorganic additive is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and most preferably 0.1 to 1 part by weight based on 100 parts by weight of the polymer solution. When the amount of the hydrophilic inorganic additive is less than 0.01 parts by weight, the effect on the hydrophilicity and physical strength of the membrane may be insignificant. When it exceeds 10 parts by weight, the miscibility with the hydrophilic organic additive may be reduced, and the interaction may be difficult. Therefore, it is very important to properly control the content of the hydrophilic inorganic additive.

Examples of such hydrophilic inorganic additives include titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO), zirconia (ZrO ₂ ), and the like, and preferably silica (SiO). ₂ ) can be used.

When a method for preparing a hydrophilic inorganic additive in the form of a sol is described as a preferred example, a silica sol may be mixed to prepare a silica sol. Tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), trimethoxymethylsilane (MTMS), dimethyl diethoxysilane (DMDEOS), etc. may be used as the silica precursor, and the second solvent may be particularly limited. For example, ethanol, hydrochloric acid, distilled water, or the like may be used alone or in combination.

At this time, it is important to uniformly disperse the silica precursor in the polymer solution. In the present invention, the most effective composition of the silica sol is 50 to 70% by weight of the silica precursor, 20 to 40% by weight of ethanol and 5 to 20% by weight of distilled water. It was confirmed that.

Meanwhile, the polymer resin composition may optionally further include an additive in order to control the physical properties and uses of the polymer filtration membrane to be prepared, and the shape and size of pores formed on or inside the filtration membrane. Additives may include conventional ingredients that can achieve this purpose, such as polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymers, polyvinylpyrrolidone (PVP), lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), methanol, ethanol, isopropanol, acetone, phosphoric acid, propionic acid, acetic acid, pyridine, polyvinylpyridine, or the like may be used alone or in combination. The content of the additive may be adjusted in view of the above-mentioned purpose, preferably 0.1 to 50 parts by weight, more preferably 1 to 20 parts by weight based on 100 parts by weight of the polymer solution.

According to another embodiment of the invention, the step of applying the above-mentioned polymer resin composition on a substrate; A non-solvent induced phase transition step of precipitating the applied polymer resin composition to a non-solvent is disclosed.

The polymer resin composition may be applied on a predetermined substrate in a thickness of 10 to 300 μm, and preferably in a thickness of 50 to 250 μm.

The step of applying the polymer resin composition on the substrate may be applied without limitation to the coating or coating method of a conventionally known polymer resin. For example, in the step of applying the polymer resin composition, uniform coating may be performed over the entire surface of the substrate by using a casting knife coating device that performs line injection.

As a base material used at the time of application | coating, a nonwoven fabric, polyester-based resin, polyethylene resin, polypropylene resin, cellulose acetate, or resin in which these were mixed (blended) can be used. In addition, the substrate may have a variety of forms depending on the specific shape or characteristics of the filtration membrane is produced, specifically, the substrate may have a flat membrane or hollow fiber (hollow fiber) structure.

The non-solvent induction phase transition step is a step of forming a film according to a coagulation bath treatment, in which the applied polymer resin composition is precipitated in the non-solvent to form internal pores and to prepare a membrane. As the coagulation solvent to be used, various organic solvents which do not dissolve the polymer membrane, water, glycols and the like may be used, and preferably water, water and an organic solvent, or a coagulation solvent in which water and glycols are mixed may be used. More preferably water may be used. It is preferable that the temperature of the coagulation solvent used at this time is 0-90 degreeC, It is more preferable that it is 5-50 degreeC, It is most preferable that it is 10-30 degreeC.

The manufacturing method of the polymer filtration membrane may further comprise the step of washing and drying the product of the non-solvent induction phase transition step. Specifically, the polymer filtration membrane may be finally obtained by washing the resultant product of the non-solvent induction phase transition step using a solvent that does not dissolve and drying at a predetermined temperature. Acetone, methanol, ethanol, water and the like may be used for washing. Preferably, water of 20 ° C. to 90 ° C. may be used. In addition, after washing the resultant is dried at a temperature of 20 ~ 200 ℃, preferably 40 ~ 100 ℃, finally a microporous polymer filtration membrane can be obtained.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to the examples described below.

Example 1

In order to prepare a silica sol which is a hydrophilic inorganic additive, 62 wt% of tetraethoxysilane (TEOS), 27 wt% of ethanol, 0.5 wt% of hydrochloric acid, and 10.5 wt% of distilled water were mixed and maintained at 60 to 70 ° C. On the other hand, in order to make a polymer solution, 11% by weight of polyvinylidene fluoride (PVDF) as a hydrophobic polymer, 86% by weight of dimethylacetamide (DMAc) as a solvent, and 3% by weight of polymethyl methacrylate (PMMA) as a hydrophilic organic additive The polymer solution was prepared by mixing. A polymer resin composition was prepared by adding 0.1 part by weight of the silica sol to 100 parts by weight of the silica sol to the prepared polymer solution. While maintaining the polymer resin composition at 25 ℃ cast casting by adjusting the thickness of the casting knife to 200 ㎛ and precipitated in non-solvent water (20 ℃) for 12 hours to form a polymer film, and the formed polymer film 1 ~ 2 hours with 30 ℃ distilled water After washing, the resultant was dried in a dry oven at a temperature of 25 ° C. for 24 hours to prepare a final polyvinylidene fluoride membrane.

Example 2

A polyvinylidene fluoride membrane was prepared in the same manner as in Example 1 except that the silica sol was added in an amount of 1 part by weight in Example 1.

Example 3

A polyvinylidene fluoride membrane was prepared in the same manner as in Example 1, except that 3 parts by weight of silica sol was added.

Example 4

A bilayer hollow fiber membrane was prepared as follows.

The polymer solution for the support layer is a hydrophobic polymer, 40% by weight of polyvinylidene fluoride (PVDF), 44.5% by weight of gamma-butyrolactone (γ-Butyrolactone), 10% by weight of N-methylpyrrolidone (NMP), ethylene glycol ( EG) 2% by weight, polyvinylpyrrolidone (PVP) 3% by weight and lithium chloride (LiCl) 0.5% by weight to prepare a mixture.

The polymer resin composition for the surface layer was prepared by mixing 11% by weight of polyvinylidene fluoride (PVDF), 86% by weight of dimethylacetamide (DMAc) as a solvent, and 3% by weight of polymethyl methacrylate (PMMA) as a hydrophilic organic additive. To 100 parts by weight of the polymer solution, 1 part by weight of silica sol, a hydrophilic inorganic additive prepared in the same manner as in Example 1, 10 parts by weight of polyvinylpyrrolidone (PVP), and 1 part by weight of lithium chloride (LiCl) are prepared. It was.

Bore solution was prepared at room temperature by mixing dimethyl acetamide (DMAc) and ethylene glycol (EG) in a weight ratio of 6: 4.

The polymer solution for the support layer was discharged through the nozzle at the same time as the thermal induction phase transition method through the nozzle at 140 ° C., and the polymer resin composition for the surface layer by the non-solvent phase transition method at the nozzle at room temperature. The radiation discharge amount was discharged in a ratio of support layer: coating layer: inner hole = 3: 1: 2. Thereafter, the formed hollow fiber membrane was immersed in a distilled water coagulation bath, which is a non-solvent at 5 ° C, washed 12 hours with distilled water at 40 ° C, and dried for 24 hours to prepare a final polyvinylidene fluoride hollow fiber membrane.

Comparative Example 1

A polyvinylidene fluoride membrane was prepared in the same manner as in Example 1, except that 14 wt% of polyvinylidene fluoride (PVDF) was used without adding a hydrophilic organic additive in Example 1.

Comparative Example 2

A polyvinylidene fluoride membrane was prepared in the same manner as in Example 1, except that silica sol was not added in Example 1.

Comparative Example 3

A polyvinylidene fluoride hollow fiber membrane was prepared in the same manner as in Example 4 except that the silica sol was not added to the polymer layer composition for the surface layer of Example 4.

Comparative Example 4

In the polymer solution for the support layer of Example 4, polyvinylidene fluoride (PVDF) was adjusted to 35% by weight and gamma-butyrolactane (γ-Butyrolactone) to 49.5% by weight, and polyvinylpyrrole in the polymer resin composition for the surface layer A polyvinylidene fluoride hollow fiber membrane was prepared in the same manner as in Example 4, except that 15 parts by weight of pig (PVP) was added and tetraethoxysilane (TEOS), a precursor, was added in place of silica sol. It was.

The composition of the polymer resin composition used in Examples and Comparative Examples is summarized in Table 1 below.

Test Example 1

In order to measure the degree of hydrophilization of the surface of the polyvinylidene fluoride resin film prepared according to Examples 1 to 4 and Comparative Examples 1 to 4, the contact angle was measured using a contact angle measuring instrument (S. Phoenix. The results are shown in Table 2 (flat membrane) and Table 3 (hollow fiber membrane).

As shown in Table 2, for the initial contact angle, the polyvinylidene fluoride film prepared according to Examples 1 to 3 to which silica sol was added as a hydrophilic inorganic additive was compared with Comparative Example 2 to which silica sol was not added as a hydrophilic inorganic additive. The low contact angle indicates that the hydrophilicity is improved. As the content of the silica sol, which is a hydrophilic inorganic additive, increases, the contact angle decreases, thereby improving the hydrophilicity. This shows that the polyvinylidene fluoride film whose hydrophilicity is improved by polymethyl methacrylate (PMMA), which is a hydrophilic organic additive, has further improved hydrophilicity by silica sol, which is a hydrophilic inorganic additive.

In addition, the polyvinylidene fluoride film prepared according to Comparative Example 1, in which silica sol, which is a hydrophilic inorganic additive, and no polymethyl methacrylate (PMMA), which is a hydrophilic organic additive, was added, polymethyl methacrylate, which is a hydrophilic organic additive ( Compared with Example 2 which added PMMA), it turns out that a contact angle is high and hydrophilicity falls. This is due to the hydrophilicity of the membrane due to the interaction between the two additives when the hydrophilic inorganic additive silica sol and the hydrophilic organic additive polymethyl methacrylate (PMMA) are added at the same time than the membrane in which the hydrophilic inorganic additive silica sol is added alone. It shows a lot of improvements.

In the case of the initial contact angle of the polyvinylidene fluoride double layer hollow fiber membrane prepared according to Example 4 and Comparative Example 3, as shown in Table 3, silica sol was added as compared to Comparative Example 3, in which the silica sol as a hydrophilic inorganic additive was not added. It can be seen that the contact angle of the bilayer hollow fiber membrane prepared according to Example 4 is reduced to improve hydrophilicity. In addition, in the case of Comparative Example 4 prepared by adding tetraethoxysilane (TEOS), which is a precursor for preparing a silica sol, as an inorganic additive, the initial contact angle was increased. This shows that tetraethoxysilane (TEOS) is not suitable as a hydrophilic inorganic additive, and that the silica sol form prepared as a precursor helps to improve hydrophilicity.

On the other hand, it can be seen that the overall contact angle was lower than that of Example 2, which was prepared by the addition of the same hydrophilic inorganic additive silica sol. This is because a small amount of the hydrophilic inorganic additive and the hydrophilic organic additive are lost due to the high temperature of the support layer discharged by the heat induction phase transition method in the process of discharging the double layer hollow fiber membrane through the nozzle.

Test Example 2

In order to measure the net permeation flux of the polyvinylidene fluoride membranes prepared in Examples 1 to 3 and Comparative Examples 1 and 2, an average value of the net permeate flux was measured under a 0.1 bar vacuum condition using a circular porous plate having a diameter of 40 mm. The results are shown in Table 2 above.

It can be seen that the membrane permeation fluxes of Examples 1 and 2 in which silica sol was added were increased compared to the permeation flux of polyvinylidene fluoride membrane prepared according to Comparative Example 2, in which silica sol, which is a hydrophilic inorganic additive, was not added. This is a result of improving the hydrophilicity of the film by the silica sol, a hydrophilic inorganic additive.

On the other hand, it can be seen that the permeation flux of the polyvinylidene fluoride membrane prepared according to Example 3 in which the content of the silica sol is added at least 3 parts by weight is significantly reduced. This is because when the content of the silica sol, which is a hydrophilic inorganic additive, exceeds a predetermined amount, the aggregation of the silica sol occurs to block pores of the membrane.

Test Example 3

In order to measure the net permeation flux of the polyvinylidene fluoride hollow fiber membranes prepared according to Examples 4, Comparative Examples 3 and 4, four hollow fiber membrane samples having an effective membrane length of 10 cm were inserted into a tubular tube, and then fixed with epoxy. A -end type membrane module was produced. Distilled water was introduced into the module at a pressure of 1 kg / cm 2, and the pure permeation flux per unit area was measured by measuring the amount of water permeated from the inside of the hollow fiber membrane and the results are shown in Table 3 above.

It can be seen that the permeation flux of the polyvinylidene fluoride double layer hollow fiber membrane prepared according to Example 4 with the addition of the silica sol, which is a hydrophilic inorganic additive, was increased than that of the hollow fiber membrane of Comparative Example 3 without the addition of the silica sol. That is, the permeation flux of the bilayer hollow fiber membrane prepared by adding together with the hydrophilic inorganic additive silica sol was higher than that of the bilayer hollow fiber membrane prepared by adding polymethylmethacrylate (PMMA), which is a hydrophilic organic additive alone. This is a result of improving the hydrophilicity of the film by silica sol which is a hydrophilic inorganic additive.

Test Example 4

In order to confirm the crystal structure of the polyvinylidene fluoride film prepared according to Examples 2 and 3, Comparative Examples 1 and 2, X-ray diffraction analysis was performed with a radiation source of 40 kV and 20 to 30 mA and a scanning angle of 5 to 50 °. The results are shown in FIG. 1.

As shown in Fig. 1 (a), the crystal structures of the films prepared according to Comparative Example 1 without adding hydrophilic organic additive polymethyl methacrylate (PMMA) had peak values of 18 °, 20 °, 26 ° and 40 °. It can be seen that it is represented by the α phase having a. However, as shown in Fig. 1 (b), the crystal structure of the film prepared by Comparative Example 2 to which the hydrophilic organic additive polymethyl methacrylate (PMMA) was added appeared as β phase having peak values of 20 ° and 36 °. It can be seen that. This is a change in the crystal structure of polyvinylidene fluoride by polymethyl methacrylate (PMMA) which is a hydrophilic organic additive.

That is, the hydrophilicity of the polyvinylidene fluoride film is improved by polymethyl methacrylate (PMMA), which is a hydrophilic organic additive, while the mechanical strength of the polyvinylidene fluoride is changed from alpha phase to beta phase. There is a problem. However, the polyvinylidene fluoride membranes prepared according to Examples 2 and 3 prepared by adding silica sol, a hydrophilic inorganic additive, as shown in FIG. The results show that the strength can be increased.

Test Example 5

In order to confirm the cross-sectional structure of the polyvinylidene fluoride hollow fiber membranes prepared according to Example 4 and Comparative Example 3, the results of measurement at 70 magnification using an optical microscope (Olympus, AHMT3-513NU) were respectively measured. And (b).

As shown in FIG. 2, the average outer diameter of the polyvinylidene fluoride bilayer hollow fiber membrane is about 1300 μm, and the average inner diameter is about 700 μm, and the cross-sectional structure of the surface layer is a finger structure.

The preferred embodiment of the present invention has been described in detail above. The description of the present invention is for illustrative purposes, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is shown by the claims below rather than the detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concepts of the claims are included in the scope of the present invention. Should be interpreted.

Claims (10)

1. (a) mixing a hydrophobic polymer base resin, a first solvent, and a hydrophilic organic additive to prepare a polymer solution;

   (b) preparing a hydrophilic inorganic additive in sol form; And

   (c) adding the hydrophilic inorganic additive to the polymer solution;

   Polymer resin composition production method for producing a filtration membrane comprising a.
2. The method of claim 1,

   The polymer solution is 1 to 50% by weight of the hydrophobic polymer base resin, 1 to 80% by weight of the first solvent and 0.01 to 50% by weight of the hydrophilic organic additive, the method for producing a polymer resin composition for manufacturing a filtration membrane.
3. The method of claim 1,

   The hydrophobic polymer base resin may be polyethersulfone (PES), polysulfone (PSf), polyther ketone (PEK), polytherther ketone (PEEK), sulfonated polymer, polyvinylidene fluoride (PVDF) ), Polytetrafluoroethylene (PTFE), polyvinylidene chloride (PVDC), chlorinate polyvinylchloride (CPVC), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and ethylenechlorotrifluoroethylene Method for producing a polymer resin composition for producing a filtration membrane, characterized in that at least one member selected from the group consisting of (ECTFE).
4. The method of claim 1,

   The hydrophilic organic additives include polyacrylonitrile (PAN), polyethylene oxide (PEO), polyvinylacetate (PVAc), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polypropylene glycol (PPG) and polyethylene Oxide-polypropylene oxide block copolymer (PEO-PPO-PEO) is a method for producing a polymer resin composition for filtration membranes, characterized in that at least one member selected from the group consisting of.
5. The method of claim 1,

   The hydrophilic inorganic additive is a method for producing a polymer resin composition for filtration membranes, characterized in that added to 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymer solution.
6. The method of claim 1,

   The hydrophilic inorganic additive is at least one member selected from the group consisting of titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO) and zirconia (ZrO ₂ ). Method for producing a polymer resin composition for production.
7. The method of claim 1,

   The step (b) is a method for producing a polymer resin composition for preparing a filtration membrane, characterized in that the mixture is carried out by mixing the silica precursor and the second solvent.
8. The method of claim 7, wherein

   The silica precursor is at least one selected from the group consisting of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), trimethoxymethylsilane (MTMS) and dimethyl diethoxysilane (DMDEOS) Method for producing a polymer resin composition for production.
9. Applying the polymer resin composition of claim 1 on a substrate; And

   A non-solvent induced phase transition step of precipitating the applied polymer resin composition to a non-solvent;

   Polymer filter membrane manufacturing method comprising a.
10. The method of claim 9,

    The filtration membrane is characterized in that it has a flat membrane or hollow fiber structure.

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