KR20130040622A - The preparation method of hollow fiber membrane with high permeation using hydrophilized polyvinylidenefluoride for water treatment - Google Patents

Abstract

PURPOSE: A method for fabricating a hollow fiber for water treatment using hydrophilic polyvinylidene fluoride with high permeability is provided to improve penetration speed using a solvent-induced phase separation method. CONSTITUTION: A method for fabricating a hollow fiber for water treatment using hydrophilic polyvinylidene fluoride resin with high permeability comprises: a step of preparing an alkali solution, first and second polymer solutions; a step of mixing the first and second polymer solutions and preparing a polyvinylidene fluoride resin spinning solution at 20-100 deg. C. The alkali solution is selected among sodium hydroxide and potassium hydroxide. The first polymer solution is prepared by dissolving the alkali solution and polyvinylidene fluoride resin in a solvent. The second polymer solution is prepared by adding an inorganic additive and an organic additive to the polyvinylidene resin and dissolving in the solvent.

Description

The preparation method of hollow fiber membrane with high permeation using hydrophilized polyvinylidenefluoride for water treatment

The present invention relates to a method for producing a high-strength hollow fiber membrane for high-strength water treatment after hydrophilic modification of a part of polyvinylidene fluoride resin, and more specifically, polyvinylidene fluoride resin is hydrophilized by using an aqueous alkali solution to form a first polymer solution. Prepare a spinning solution by adding an inorganic additive and an organic additive to a polyvinylidene fluoride resin, dissolving it in a solvent to prepare a second polymer solution, and mixing them, and then, using a double-deposit, a low temperature external coagulation bath. It relates to a method for producing a hollow fiber membrane for high permeability water treatment by spinning.

Polysulfone (Polysulfone; PSf), Polyethersulfone (PES), Polyvinylidenefluoride (PVDF), Polyethylene, Polypropylene (Polypropylene; PP), Polytetrafluoroethylene (PTFE), Polycarbonate (PC), Polyamide (PA), Polyester, Polyvinylchloride (PVC), Cellulose Nitride Cellulosenitrate, Regenerated Cellulose, Celluloseacetate (CA), Cellulosetriacetate (CTA), Polyacrylonitrile (PAN) and the like are used. Polysulfone (PSf), polyethersulfone (PES), and polyvinylidene fluoride (PVDF) are hydrophobic materials, and generally, ultrafiltration membranes or microfiltration hollow fiber membranes are prepared using a phase transfer method. Polysulfone or polyisulfone have a much higher phase transition speed and lower viscosity than polyvinylidene fluoride, so that a large amount of hollow fiber membranes can be produced in a short time, but the mechanical strength is weak, so that the membrane surface is easily damaged or cut, Due to chemistry, the membrane deteriorates rapidly during long-term use, and there is a problem of long-term use due to membrane contamination due to the relatively large pore size of the membrane. Although the permeation rate is large, the fouling phenomenon of the membrane is severe and there is a problem of causing the passage of fine organic materials. Polyethylene or polypropylene is a typical crystalline polymer, and mainly melts the polymer and extrudes it, and then stretches the amorphous region existing between the crystal and the crystal to form voids, thereby having a very high porosity. Therefore, the hollow fiber membrane produced by this method has a high permeation flux, but the pores are slit-shaped, have a relatively large pore and pore distribution, it is difficult to control the membrane contamination, and the separation performance is limited, so sewage treatment There is a problem that is used extremely limited. Polycarbonate or polyester material is manufactured as a separation membrane using the track etching method due to the characteristics of the material, but this method has the advantage of producing a uniform void, but is extremely limited in the microfiltration membrane with a very small porosity, a large void, Large scale membrane production has a difficult problem. Polymers such as cellulose nitrate, Regenerated Cellulose, Celluloseacetate (CA), Cellulosetriacetate (CTA), and Polyacrylonitrile (PAN) are relatively hydrophilic polymers. As a separator, a separation membrane is manufactured by using a solvent induction phase transition method, and has a high permeation flux, but has a weak chemical resistance and durability, and has a problem of long-term use due to breakage or damage when forming into a hollow fiber membrane.

Korean Patent Publication No. 2005-18624 discloses the preparation and application of a porous membrane having both a three-dimensional mesh structure and a spherical structure. In this patent, in order to achieve the porous membrane, the thermoplastic resin is dissolved in a solvent, and the resin solution is solidified by ejecting the resin solution from the spinning nozzle into the cooling liquid to change the composition of the cooling liquid on one side and the other side of the membrane. A method having both a three-dimensional mesh structure and a spherical structure, a method of forming a three-dimensional mesh structure by applying a resin solution to at least one side of the porous membrane having a spherical structure, and then immersing in a coagulating solution, and a resin for forming a three-dimensional mesh structure A method having both a three-dimensional mesh structure and a spherical structure in which a solution and a resin solution for forming a spherical structure are simultaneously discharged from a triple spinning nozzle and then solidified. Bulte et al., Published in 1996, published by A.M.W. Bulte, M.H.V. Mulder, C. A. Smolders, H. Strathmann, Diffusion induced separation with crystallizable nylons. II. (Relation to final membrane morphology, Journal of membrane science, 121, 51-58 (1996)], when preparing a membrane using a thermoplastic resin, the membrane having a spherical structure by dissolving at high temperature and immersing in a low temperature coagulation bath The production is started. Lee et al., Published in 1994, S.-G. Li, G.H. Koops, M.H.V. Mulder, T. van den Boomgaard, C.A. Smolders, Wet spinning of integrally skinned hollow fiber membranes by a modified dual-bath coagulation method using a triple orifice spinneret, Journal of membrane science, 94, 329-340 (1994), albretz et al. W. Albrecht, K. Kneifel, Th. Weigel, R. Hilke, R. Just, M. Schossig, K. Ebert, A. Lendlein, Preparation of highly asymmetric hollow fiber membranes from poly (ether imide) by a modified dry-wet phase inversion techniquie using a triple spinneret, Journal of membrane science, 262, 69-80 (2005)] discloses the production of hollow fiber membranes for pervaporation using triple spinning nozzles. Korean Patent Publication No. 2007-102012 discloses a porous hollow hydrophilic polyvinylidene fluoride resin containing an average particle diameter of about 5 microns, a plurality of rod-shaped particles having a particle size of 5 microns or more, and a plurality of spherical particles having an average particle diameter of 5 microns or less. Started manufacturing of the desert. In Korean Patent Laid-Open Publication No. 2007-113374, a plurality of polymer nanofibers which are located inside the membrane from the hollow center of the hollow fiber membrane to the outside and are exposed on the membrane cross-section and have an average particle diameter of 1 to 5 microns or less An inner layer comprising a plurality of microspherical particles, a plurality of polymer nanofibers located on top of the inner layer and having an average diameter of 500 nanometers or less are exposed to the cross-section, and at the same time, a plurality of intermediates having an average particle diameter of more than 5 microns and 10 microns An intermediate layer comprising spherical particles, and a plurality of polymer nanofibers, which are located on top of the intermediate layer and have an average diameter of 500 nanometers or less, are exposed on the cross-section, and at the same time, include a plurality of microspherical particles having an average particle diameter of 1 to 5 microns or less. Disclosed is the preparation of a polyvinylidene fluoride porous hollow fiber membrane comprising a surface layer have. In addition, Korean Patent Publication No. 2007-113375 discloses the production of a polyvinylidene fluoride resin porous hollow fiber membrane having four layers having different particle diameters from a hollow central part of a hollow fiber membrane. Disclosed is a production of a polyvinylidene fluoride resin porous hollow fiber membrane comprising an inner layer comprising a plurality of spherical particles outward from a central portion of the hollow fiber membrane and a surface layer comprising a plurality of spherical fibrous particles. However, this method has a drawback of limiting water permeation because it is difficult to form large voids due to the small voids between the particles due to the spherical structure of the support layer forming the thick layer inside. In addition, since it does not have a separation active layer on the surface of the porous membrane, it has a drawback that the removal efficiency of microparticles, pathogenic bacteria, microorganisms, etc. is not high. Korean Patent Laid-Open Publication No. 2005-0056245 discloses the formation of hydrophilic vinyl monomers by irradiating polyvinylidene fluoride microporous membranes with ionizing radiation, followed by graft polymerization of these radicals on the membrane surface. It is starting to form. In addition, Korean Patent Publication No. 2006-0003347 discloses a porous hydrophilized polyvinylidene fluoride resin prepared by copolymerizing a hydrophilic monomer containing an epoxy group, a hydroxyl group, a carboxyl group, an ester group, and an amide group with a polyvinylidene fluoride monomer through suspension polymerization. The film is starting. Korean Patent Publication No. 2005-0078747 discloses a preparation example of a nanocomposite hollow fiber membrane containing hydrophilized organic clay. In addition, examples of preparing a hydrophilized polyvinylidene fluoride resin porous membrane through chemical treatment with alkali and oxidizing agent are also disclosed. However, such prior art uses additional processes such as polymerization, expensive processes such as the use of radiation, and the like, and particularly, chemical treatment methods often have the disadvantage of impairing the mechanical strength inherent in polyvinylidene fluoride resin.

[Reference 1] KR 10-2005-018624 [Document 2] KR 10-2007-102012 [Reference 3] KR 10-2007-113374 [Document 4] KR 10-2007-113375 [Reference 5] KR 10-2007-103187 [Document 6] KR 10-2005-056245 [Document 7] KR 10-2006-003347 8 KR 10-2005-078747

[Reference 1] A.M.W. Bulte, M.H.V. Mulder, C. A. Smolder, H. Strathmann, Journal of Membrane Science, 1996, Vol 121, 51-58 [2] S.-G. Li, G.H. Koops, M.H.V. Mulder, T. van den Boomgaard, C.A. Smolders, Journal of Membrane Science, 1994, Vol 94, pp. 329-240 [3] W. Albrecht, K. Kneifel, Th. Weigel, R. Hilke, R. Just, M. Schossig, K. Ebert, A. Lendlein, Journal of membrane science, 2005, Vol 262, pp. 69-80

In order to solve the above problems, the present inventors prepare a first polymer solution by mixing a polyvinylidene fluoride resin, an aqueous alkali solution and a good solvent, and mixing the polyvinylidene fluoride resin with an inorganic additive, an organic additive, and a good solvent. The present invention was completed by preparing a spinning solution by mixing with the prepared second polymer solution and spinning the prepared spinning solution into a low temperature coagulation bath to prepare a hollow fiber membrane for water treatment having a high permeation flux.

In the manufacturing method of the hollow fiber membrane for water treatment using the hydrophilic polyvinylidene fluoride resin which has a high permeability,

1) dissolving a metal hydroxide selected from one or more of sodium hydroxide and potassium hydroxide in pure water to prepare 50 to 100% by weight of an aqueous alkali solution;

2) dissolving the aqueous alkali solution and polyvinylidene fluoride resin in a solvent at a temperature of 20 ℃ to 100 ℃ to prepare a first polymer solution;

3) preparing a second polymer solution by adding an inorganic additive and an organic additive to the polyvinylidene fluoride resin and dissolving it in a solvent at a temperature of 20 ° C. to 100 ° C .;

4) mixing the first polymer solution and the second polymer solution to prepare a hydrophilized polyvinylidene fluoride resin spinning solution at a temperature of 20 ° C to 100 ° C;

5) preparing a hollow fiber membrane by spinning the hydrophilized polyvinylidene fluoride resin spinning solution into an external coagulation tank through double detention;

6) hydrothermal treatment of the hollow fiber membrane;

It relates to a method for producing a hollow fiber membrane for high permeability water treatment using a hydrophilic modified polyvinylidene fluoride resin comprising a.

In particular, the present invention is hydrophilic modification of the hydrophobic polyvinylidene fluoride resin using an alkaline solution to have a high permeation flux, while not hydrophilic polyvinyl fluoride in order to reinforce the low mechanical properties caused by hydrophilization It is used in the water treatment field by preparing a hollow fiber membrane by mixing with a Liden resin solution and preparing a spinning solution through non-solvent induced phase separation (NIPS) or diffusion induced phase separation (DIPS) The present invention relates to a method for producing a hollow fiber membrane for high permeability water treatment so as to have a high water permeability.

Hereinafter, the present invention will be described in detail.

1) Preparation of First Polymer Solution

The first polymer solution is to increase the hydrophilization by introducing a hydroxyl group (-OH) to the hydrophobic polyvinylidene fluoride resin to improve the permeation flux of the hollow fiber membrane prepared. Metal hydroxides having a hydroxyl group are mainly used to achieve this purpose, and typically sodium hydroxide (NaOH) and potassium hydroxide (KOH). The metal hydroxide is dissolved in pure water to make a saturated solution, but it is preferable to use 50 to 100% by weight. To make a saturated solution, the excess metal hydroxide should be added and then filtered. Potassium hydroxide and magnesium hydroxide are not very soluble in water, so even if you use an aqueous solution dissolved in water, water is nonsolvent for polyvinylidene fluoride polymer, so it can be mixed in a very limited amount, so the purpose of this hydrophilic reforming cannot be sufficiently achieved. . 0.01 to 3% by weight of the aqueous alkali solution prepared as described above, 1 to 10% by weight of polyvinylidene fluoride resin having a weight average molecular weight of 100,000 Daltons to 600,000 Daltons, and 87 to 98.99% by weight of a good solvent are mixed at a temperature of 20 to 100 ° C. Although prepared from the first polymer solution, it is preferable to manufacture the solution at 20 ° C. to 60 ° C., which is advantageous because it can secure more economical efficiency in a low energy process. However, if the temperature is too low, it takes a long time to prepare a solution or a problem that the polymer does not dissolve well, and if it exceeds 100 ℃ water in the alkali aqueous solution is not able to achieve the desired. At this time, the solvents that can be used are dimethylformamide (N, N-Dimethylformamide; DMF), dimethylacetamide (N, N-Dimethylacetamide; DMAc), normal methylpyrrolidone (N-Methyl-2-pyrrolidone; NMP), dimethylsulfur Dimethylsulfoxide (DMSO) is one or more selected from, more preferably soluble dimethylformamide is used. When the aqueous alkali solution is used at less than 0.01% by weight, hydrophilization cannot be sufficiently achieved, and when the aqueous alkali solution is used at more than 3% by weight, the polyvinylidene fluoride resin solution is solidified by the water contained in the aqueous alkali solution. When the concentration of the polyvinylidene fluoride resin is less than 1% by weight, only a small amount of the hydrophilized polyvinylidene fluoride resin can be obtained, and thus, sufficient hydrophilicity objectives cannot be achieved. Too much polyvinylidene fluoride resin is present, and there is a difficulty in making it into a solution.

2) Preparation of Second Polymer Solution

In the present invention, the second polymer solution can be obtained by dissolving a mixed resin in which an inorganic additive and an organic additive are added to a polyvinylidene fluoride resin in a good solvent. Polyvinylidene fluoride resin is composed of 10 to 25% by weight of the weight average molecular weight 200,000 Daltons to 700,000 Daltons alone or a mixture of two or more kinds, when used alone, it is preferable to use a polymer of 250,000 Daltons to 700,000 Daltons 2 When composed of a mixture of two or more species, it is preferable to use a low molecular weight polyvinylidene fluoride resin of 200,000 Daltons to 400,000 Daltons and a high molecular weight polyvinylidene fluoride resin of 400,000 Daltons to 700,000 Daltons. If the polymer is less than 10% by weight, the mechanical strength is weak, so it is easily cut when used for water treatment by molding into a hollow fiber membrane, and inconvenient in use, and when it exceeds 25% by weight, it is difficult to mold due to the high viscosity. It is difficult to dissolve, and the voids are so small that the permeation flow rate is low, making it unsuitable for use as a hollow fiber membrane for water treatment. If the weight average molecular weight of the polymer is less than 200,000 Daltons, the mechanical strength is weak, which makes it unsuitable for use as a hollow fiber membrane for water treatment. Because of its flow rate, it is not suitable for use as a desired hollow fiber membrane for water treatment. Because polyvinylidene fluoride resin is hydrophobic, it has a weak affinity with water, so that the phase transition speed is increased and inorganic additives are used to control them. These inorganic additives play an important role in forming voids in the polyvinylidene fluoride resin hollow fiber membrane. . 1-10% by weight of any one or more inorganic additives selected from lithium chloride (LiCl), zinc chloride (ZnCl ₂ ), magnesium chloride (MgCl ₂ ), magnesium sulfate (MgSO ₄ ) is used. If the inorganic additive is less than 1% by weight, the effect of addition is insignificant, and the pore formation is poor. If the inorganic additive is more than 10% by weight, the presence and dispersibility of insoluble additives worsen, resulting in the formation of irregular macropores and poor hollow fiber membranes during manufacturing. There is a problem. Organic additives are hydrophilic polymers or materials such as polyethylene glycol (PEG), dextran (Dextrane), polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene oxide (PEO), Polyvinylacetate (PVAc), maleic acid (maleic acid) at least one selected from 1 to 10% by weight is mixed. If the hydrophilic organic additive is less than 1% by weight, the effect of exhibiting hydrophilicity is insignificant, which shows a low permeation flux when forming into a hollow fiber membrane, and when the hydrophilic organic additive is more than 10% by weight, it shows a high permeation flux. There is a problem in long-term use due to chemical resistance. The good solvent uses 55 to 88% by weight in at least one selected from dimethylformamide, dimethylacetamide, normal methylpyrrolidone, and dimethylsulfuroxide. The second polymer solution mixed as described above is prepared at 20 ° C. to 100 ° C., and is difficult to dissolve and has a high viscosity below 20 ° C., and if it exceeds 100 ° C., partial melting by recrystallization after partial melting occurs. Solidification occurs sequentially and is difficult to mold.

3) Manufacture of spinning solution

A spin solution is prepared by mixing the hydrophilic modified first polymer solution with 5 to 30% by weight of the second polymer solution. When the first polymer solution is less than 5% by weight, the effect of hydrophilic modification of the polyvinylidene fluoride resin is hardly exhibited, so that the permeation flux is very low. When the first polymer solution exceeds 30% by weight, the permeation flux is high. There was a problem that the low mechanical strength is unsuitable for use as a hollow fiber membrane for water treatment. The spinning solution maintains a temperature of 20 ℃ to 100 ℃, it is difficult to dissolve below 20 ℃, it is difficult to spin through double detention because the viscosity is very high. The prepared spinning solution is degassed using a decompression device and filtered using a metal net to remove impurities or inexpensive residues present therein.

4) Coagulant Manufacturing

A coagulant is represented by an internal coagulant, that is, a bore solution and an external coagulant bath or a phase transfer tank, in which the internal coagulant is necessary to form the hollow of the hollow fiber membrane and the external coagulant is a solution required to phase-transfer and solidify the spun polymer. to be. The internal coagulant mainly uses water or ethylene glycol as the nonsolvent, and the amount of normal methylpyrrolidone or dimethylacetamide, dimethylformamide, dimethylsulfuroxide, etc., as a mixed good solvent when mixed with the nonsolvent at room temperature. The ratio of the solvent is prepared in two to eight to eight to two and degassed. Preferably, the same good solvent as the good solvent mixed in the spinning solution is used. The external coagulant uses water or ethylene glycol as a non-solvent and one or more single or mixed solvents selected from normal methylpyrrolidone or dimethylacetamide, dimethylformamide, dimethylsulfuroxide, etc., preferably the same as the spinning solution. It is preferable to use a solvent of a kind, the amount of which is 5% or less in the non-solvent. Non-solvents may be used alone. The temperature ranges from 20 ° C to 70 ° C, where the pore size decreases and the porosity decreases below 20 ° C. The permeation flux decreases significantly. Above 70 ° C, the permeation flux increases due to the large surface voids, but the mechanical strength is increased. It was low and unsuitable for use as a hollow fiber membrane for water treatment.

5) Preparation of Hollow Fiber Membrane

Send the spinning solution prepared in step 3) to the outer tube of the double detention, and the internal coagulant prepared in step 4) flows into the central tube of the double detention to spin into an external coagulation tank to solidify the spinning solution to produce a hollow fiber membrane The hollow fiber membrane thus prepared is wound up by removing the remaining solvent and free organic additives from the cleaning tank. The temperature of the double detention is 20 ° C to 100 ° C and preferably 30 ° C to 80 ° C. If the temperature of double detention is less than 20 ℃, it is difficult to spin due to high viscosity. If it exceeds 100 ℃, partial melting and recrystallization are repeated, and it is not continuously formed due to the formation of solidified crystals. The spinning process becomes impossible. The internal coagulant passes through a narrow narrow tube present in the center of the detention, wherein the temperature of the internal coagulant is 1 ° C to 90 ° C, preferably 5 ° C to 80 ° C. The washing tank is configured to control the increase of the extracted solvent by continuously exchanging a predetermined amount because water is used alone and the concentration of the extracted solvent to the free organic additive increases during long-term use.

6) washing process

In addition, the present invention may further comprise a washing process to remove the organic matter including the remaining solvent in and out of the membrane of the hollow fiber membrane transferred to the winder from the washing tank. The use of water as the washing liquid is preferred, and the washing time is not particularly limited, but at least 4 hours or more and 2 days or less.

As described in detail above, the hollow fiber membrane for high permeability water treatment using the hydrophilized polyvinylidene fluoride resin prepared according to the present invention is mixed with a hydrophilized polyvinylidene fluoride resin solution and an unmodified polyvinylidene fluoride resin solution at low temperature. The hollow fiber membrane for water treatment having a very high permeation rate can be produced by molding into a hollow fiber membrane by using a solvent-induced phase separation method.

1 is a scanning electron micrograph of the cross-section of the membrane prepared by the present invention.
Figure 2 is a scanning electron micrograph of the outer surface of the membrane prepared by the present invention.
Figure 3 is a scanning electron micrograph of the inner surface of the membrane prepared by the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example

Example 1

To 5% by weight of polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, sodium hydroxide was dissolved in ultrapure water prepared by using a reverse osmosis membrane, and 0.1% by weight of an aqueous alkali solution, which became 70% by weight, was added. The first polymer solution was prepared by dissolving in weight%, and 8 weight% of inorganic chloride and hydrophilic organic additive lithium chloride, 3 weight% of polyethylene glycol and 3 weight% of polyvinylidene fluoride resin were prepared in 15 weight% of polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons. 3% by weight of pyrrolidone was added and dissolved in dimethylformamide at 50 ° C so that the composition ratio of dimethylformamide was 71% by weight. 20% by weight of the first polymer solution was added to the prepared second polymer solution to maintain bubbles at 60 ° C. to remove air bubbles in the solution. The internal coagulant was prepared at 25 ° C. with a water to dimethylformamide ratio of 6 to 4, and then degassed using a decompression device. External coagulant was added by adding 1% by weight of dimethylformamide to ultrapure water and maintained at 25 ° C. The spinning solution was transferred to the outer tube of the double-detention holding the 60 ℃ by a pulse-free metering gear pump, and the internal coagulant was also transferred to the center tube of the double-detention using a fixed-quantity gear pump and spun into an external coagulation tank. The spun polymer solution solidified as the phase transition occurred as it flowed into the external coagulant, was formed into a hollow fiber membrane, and the molded hollow fiber membrane was wound up through a washing tank. The wound hollow fiber membrane was immersed in pure water for about 4 hours to remove the remaining solvent. The immersed hollow fiber membrane was taken out and dried, and then an experimental mini module was manufactured to measure pure permeability and rejection rate. 1 shows a photograph taken by scanning electron microscope (SEM) of a cross section of a hollow fiber membrane prepared according to the present embodiment, [FIG. 2] shows a surface active layer of a hollow fiber membrane, and [FIG. 3] shows an inner surface. Are shown respectively.

[Example 2]

In Example 1, the first polymer solution was mixed with 10 wt% of the second polymer solution to 90 wt%, and was carried out as in Example 1.

[Example 3]

Alkali aqueous solution in Example 1 was prepared by using 100% by weight of sodium hydroxide to prepare a hydrophilic polymer was carried out the same experiment as in Example 1.

Example 4

0.5 wt% of an aqueous alkaline solution containing 100 wt% of potassium hydroxide instead of sodium hydroxide in the components of the first polymer solution, 5 wt% of polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, and 94.5 wt% of dimethylformamide The experiment was carried out in the same manner as in Example 1 by changing to.

[Example 5]

 In Example 1, a first polymer solution was prepared by mixing 5% by weight of a polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, 94.9% by weight of a dimethylformamide solvent, and 1.0% by weight of an aqueous solution of 70% by weight of sodium hydroxide at 30, It carried out similarly to Example 1.

[Example 6]

In Example 1, the preparation temperature of the first polymer solution is 70 ° C., and the second polymer solution is 20% by weight of polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, 8% by weight of lithium chloride, 3% by weight of polyethylene glycol, After mixing 3% by weight of polyvinylpyrrolidone, it was dissolved in 66% by weight of dimethylformamide at 80 ° C., mixed with the first polymer solution to be 80 to 20, and prepared as a spinning solution. Was carried out.

 [Example 7]

 In Example 1, 0.1% by weight of an aqueous alkali solution containing 70% by weight of sodium hydroxide was added to 2% by weight of polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, and then dissolved in dimethylformamide at 30 to obtain a first polymer solution. Preparation was carried out as in Example 1.

 [Example 8]

 Lithium chloride 3% poly and 15% by weight of a mixed resin of 25% by weight of a polyvinylidene fluoride resin having a weight average molecular weight of 210,000 Daltons and 75% by weight of a polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons in Example 1 After adding 5% by weight of vinyl alcohol, it was dissolved in dimethylformamide at 50 ° C. to prepare a second polymer solution, and water and dimethylformamide were mixed at 5: 5 with an internal coagulant and carried out as in Example 1.

 [Example 9]

 In Example 1, the composition of the internal coagulation solution was set to a ratio of water and dimethylformamide of 2: 8, and the external coagulation bath was mixed with ultrapure water treated with a reverse osmosis membrane with 5% by weight of dimethylformamide.

 [Example 10]

 In Example 1 was carried out as in Example 1 with the temperature of the spinning solution to 30 ℃.

 [Example 11]

 In Example 1, the temperature of the internal coagulating solution was set to 80 ° C., which was carried out as in Example 1.

Comparative Example 1

 In Example 1, 5 wt% of an aqueous alkali solution and 5 wt% of a polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons were dissolved in dimethylformamide to prepare a first polymer solution. However, due to the high concentration of alkaline aqueous solution, a part of the polyvinylidene fluoride resin solution gelled and could not be used as a spinning solution.

 Comparative Example 2

 In Example 1 was carried out as in Example 1 using only the second polymer solution as a spinning solution.

 [Comparative Example 3]

 In Example 1, 3% by weight of polyethylene glycol and 3% by weight of polyvinylpyrrolidone were mixed with 15% by weight of a polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, dissolved in dimethylformamide, and used as a second polymer solution. It carried out as in Example 1 above.

 [Comparative Example 4]

 In Example 1, 8% by weight of lithium chloride was mixed with 15% by weight of a polyvinylidene fluoride resin having a weight average molecular weight of 520,000 Daltons, dissolved in dimethylformamide, and used as a second polymer solution. .

 [Comparative Example 5]

 In Example 1, the temperature and spinning temperature of the second polymer solution were 120 ° C., and the same procedure as in Example 1 was performed. However, as the spinning temperature reached 120 ° C., the hollow fiber membranes were easily broken during spinning, making continuous spinning difficult.

 [Comparative Example 6]

 In Example 1, both the internal coagulant and the external coagulant were carried out as in Example 1 using pure water.

 [Experimental Example 1]

 The hollow fiber membranes prepared in Examples and Comparative Examples were prepared as modules to measure pure permeability, rejection rate (polystyrene monodisperse particles; diameter of 100 nanometers), tensile strength, and elongation.

Measurement of pure permeability;

50 hollow fiber membranes were inserted into a 30 cm polycarbonate transparent tube, and both ends were potted using a polyurethane or epoxy adhesive to prepare an experimental minimodule having an effective membrane area of 0.0651 m 2. 20 ° C. pure water was supplied to one side of the module in a cross flow method under 50 kPa to measure the amount of permeated water, and then converted into unit time and per unit membrane area.

Measurement of exclusion rate;

A 500 nanometer aqueous solution was prepared by dispersing an aqueous solution of monodisperse polystyrene particles having a size of 100 nanometers in pure water at 20 ° C. Two hollow fiber membranes were inserted into a 20 cm transparent tube, and both sides were potted to prepare a mini-module for measuring exclusion rate. Particle aqueous solution was supplied to one side of the prepared module at a pressure of 50 kPa to measure the permeated aqueous solution and polystyrene concentration dispersed in the initially supplied raw water using an ultraviolet spectrometer (Shimadzu, UV-1601PC).

Then, the exclusion rate was determined by converting the relative ratio of the absorption peak measured at a wavelength of 240 nanometers into a percentage using the following equation.

Exclusion rate (percent) = (feed water concentration-permeate concentration) ÷ feed water concentration X 100

Measurement of tensile strength elongation;

Tensile strength and elongation were averaged by measuring a crosshead speed 5 times at a rate of 50 millimeters per minute using a tensile tester.

The results of each transmission experiment are shown in Table 1.

Pure Permeate Flux
(L / ㎡-hr) at 20 ℃, 50kPa % Rejection
at 20 ℃, 50kPa Breaking Strength (N) Example 1 476 97.5 3.9 Example 2 448 97.2 4.2 Example 3 381 98.1 3.5 Example 4 462 96.8 3.3 Example 5 498 97.8 2.9 Example 6 456 96.9 3.7 Example 7 406 96.4 3.7 Example 8 375 99.1 3.6 Example 9 450 95.4 2.9 Example 10 402 98.1 3.7 Example 11 479 96.4 3.3 Comparative Example 1 - - - Comparative Example 2 230 94.8 2.9 Comparative Example 3 175 99.1 4.1 Comparative Example 4 143 99.5 3.8 Comparative Example 5 - - - Comparative Example 6 156 89.1 4.5

As shown in Table 1, the hollow fiber membrane according to the present invention showed an excellent permeation rate compared to the comparative example. The pure permeation flux showed 375 to 479 L / m 2 -hr at 20 ° C. and a pressure of 50 kPa, indicating that the pure permeation flux was much superior to the pure permeate flow rates 143 to 230 L / ° C.-hr shown in Comparative Examples 1 to 6. In the case of Comparative Example 1 it was impossible to spin at a high viscosity of the spinning solution, in the case of Comparative Example 5 was broken so easily during spinning was impossible. Comparative Example 2 is a hollow fiber membrane which is not hydrophilized by preparing a hollow fiber membrane without adding a hydrophilic polymer solution, and Comparative Examples 4 and 5 are inorganic additives and hydrophilic organic additives that play a large role in pore formation and hydrophilization. It can be seen that there is almost no hydrophilic effect with the polymer solution which is not added. As shown in Comparative Example 6, it can be seen that the composition of the internal coagulant and the external coagulant is also very important.

High-permeability hollow fiber membranes made of hydrophilized polyvinylidene fluoride-based resins can be manufactured as modules and used in water treatment, sewage treatment, sewage reuse, seawater desalination pretreatment, etc. Can be used as a desert.

Claims (11)

In the manufacturing method of the hollow fiber membrane for water treatment using the hydrophilic polyvinylidene fluoride resin which has a high permeability,
1) dissolving a metal hydroxide selected from one or more of sodium hydroxide and potassium hydroxide in pure water to prepare 50 to 100% by weight of an aqueous alkali solution;
2) dissolving the alkali aqueous solution and polyvinylidene fluoride resin in a solvent at a temperature of 20 ℃ to 100 ℃ to prepare a first polymer solution;
3) preparing a second polymer solution by adding an inorganic additive and an organic additive to the polyvinylidene fluoride resin and dissolving it in a solvent at a temperature of 20 ° C. to 100 ° C .;
4) mixing the first polymer solution and the second polymer solution to prepare a hydrophilized polyvinylidene fluoride resin spinning solution at a temperature of 20 ° C to 100 ° C;
5) preparing a hollow fiber membrane by spinning the hydrophilized polyvinylidene fluoride resin spinning solution into an external coagulation tank through double detention;
6) hydrothermal treatment of the hollow fiber membrane;
Method for producing a hollow fiber membrane for high permeability water treatment using a hydrophilic modified polyvinylidene fluoride resin comprising a. The method of claim 1,
1 to 10% by weight of polyvinylidene fluoride resin, 0.01 to 3% by weight of an aqueous alkali solution and 87 to 98.99% by weight of a solvent are reacted by mixing to obtain a first polymer solution in which the polyvinylidene fluoride resin is hydrophilized. A method for producing a hollow fiber membrane for high permeability water treatment, characterized in that the production. The method of claim 2,
The solvent is a method for producing a hollow fiber membrane for high permeability water treatment, characterized in that it comprises a mixed solvent of one or two or more of normal methylpyrrolidone, dimethylformamide, dimethylsulfuroxide, dimethylacetamide. The method of claim 1,
In the step 3), the inorganic additive is at least one selected from lithium chloride, zinc chloride, magnesium sulfate, potassium sulfate, and magnesium chloride, and the organic additive is polyethylene glycol, dextran, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene oxide. At least one selected from polyvinylacetate, and a solvent is selected from at least one of normal methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethylsulfuroxide to prepare a second polymer solution by mixing. Method for producing hollow fiber membrane for water treatment. The method of claim 1,
In the step 3), 10 to 25% by weight of the polyvinylidene fluoride resin, 1 to 10% by weight of the inorganic additive, 1 to 10% by weight of the organic additive, and 55 to 88% by weight of the solvent, and the high permeability water treatment hollow Desert recipe. The method of claim 1,
In the step 4), 5 to 30% by weight of the first polymer solution is mixed with respect to 70 to 95% by weight of the second polymer solution to prepare a spinning solution. The method of claim 1,
In the step 5), the spinneret is composed of a double detention to discharge the internal coagulating solution to the center tube, and to discharge the spinning solution prepared in step 4) to the outer tube to form a hollow in the center. Method for producing a hollow fiber membrane for high permeability water treatment. 8. The method of claim 7,
The internal coagulating solution is a mixed solvent of 20 to 80% by weight of water and 20 to 80% by weight of at least one solvent selected from normal methylpyrrolidone, dimethylformamide, dimethylsulfuroxide, and dimethylacetamide. Method for producing hollow fiber membrane for high permeability water treatment. The method of claim 8,
The temperature of the internal coagulation liquid is 1 ℃ to 70 ℃ manufacturing method of a hollow fiber membrane for water treatment. The method of claim 1,
The external coagulation tank of step 5) is a high permeability water treatment, characterized in that 0.1 to 10% by weight of at least one solvent selected from normal methylpyrrolidone, dimethylformamide, dimethylsulfuroxide, dimethylacetamide is added to water. Method of manufacturing hollow fiber membranes. The method of claim 10,
The temperature of the external coagulation tank is a method for producing a hollow fiber membrane for high permeability water treatment, characterized in that 20 ℃ to 70 ℃.

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