KR20040074362A - Antimicrobial hollow fiber membrane and method of preparing the same - Google Patents

Abstract

PURPOSE: An antimicrobial hollow fiber membrane is provided to substantially improve bacteria inhibiting performance compared with conventional membrane by improving antibacterial activities and extend life cycle by improving staining resistance, and a method for manufacturing the same is provided. CONSTITUTION: In a hollow fiber membrane for microfiltration and ultrafiltration, the antimicrobial hollow fiber membrane is characterized in that antimicrobial is contained in the hollow fiber membrane, and content of residual antimicrobial in the hollow fiber membrane after penetrating 5,000 L/m¬2 of ordinary city water into the hollow fiber membrane is 70% or more of an initial content of the antimicrobial, wherein 0.01 to 3 wt.% of antimicrobial is contained in the hollow fiber membrane, wherein the antimicrobial is an organic or inorganic antimicrobial, wherein the organic antimicrobial is organic copper compound, organic zinc compound, chlorine phenyl ether based compound, organic nitrogen based compound, organic silicon quaternary ammonium, isothiazolin based compound, pyrithione based metal compound or a mixture thereof, and wherein the inorganic antimicrobial is silver based zeolite, copper based zeolite, zinc based zeolite, silver based silica alumina, zinc based silica alumina or a mixture thereof.

Description

Antimicrobial hollow fiber membrane and its manufacturing method {Antimicrobial hollow fiber membrane and method of preparing the same}

The present invention relates to a hollow fiber membrane having a continuous antibacterial function in the hollow fiber membrane filter and a method for manufacturing the same.

Hollow fiber membrane filter is divided into partial filtration and total filtration according to the application method. The dual filtration method has the advantage of low water consumption and simple structure of the filter, but has a disadvantage in that the membrane is easily contaminated over time, thereby shortening the life and degrading separation performance. In particular, since the microorganisms present in the feed water cannot be discharged to the outside of the filter after being separated by the membrane, breeding on the feed side and the outer membrane surface of the filter degrades the permeation characteristics of the membrane.

In order to prevent this, a method of blocking microorganisms by using a material such as silver or ceramic having antibacterial effect on the pretreatment filter or activated carbon layer before the hollow fiber membrane is used, but since it is the role of the hollow fiber membrane to completely block the microorganism, In the stage, only the level of inhibiting the introduction of microorganisms can be expected.

In addition, Japanese Patent Application Laid-Open No. 98-328659 provided an additional flow path for cleaning the whole-filtration hollow fiber membrane filter in order to prevent the microorganisms once introduced from breeding. In this method, water purification is usually performed by total filtration, and the outside of the water filter is washed with tap water through a separate flow path at a predetermined time.

This method is effective in lowering the concentration of suspended solids outside the filter, but there is a disadvantage in that the mass of microorganisms, that is, biofilm, adhered to the separator surface, which is a direct cause of deterioration of the membrane, cannot be removed.

The present invention is to provide a hollow fiber membrane excellent in antibacterial properties, excellent antibacterial performance and fouling resistance, prolonged service life by imparting continuous antimicrobial properties to the hollow fiber membrane itself.

The antimicrobial hollow fiber membrane of the present invention for achieving such a problem is characterized in that the antimicrobial agent is contained in the hollow fiber membrane, the residual antimicrobial agent content in the hollow fiber membrane is 70% or more of the initial content after using 5,000 L / m ² permeate of general tap water It is done.

In addition, the method for producing the antimicrobial hollow fiber membrane of the present invention is to produce a hollow fiber membrane by spinning the spinning dope and the internal coagulating solution composed of a hydrophobic polymer, an organic solvent and a hydrophilic compound into the air with a double tubular nozzle and then coagulated with an external coagulating solution. When the antibacterial agent is added to the spinning dope or internal coagulating solution.

Hereinafter, the present invention will be described in detail.

The antimicrobial hollow fiber membrane of the present invention is composed of a hydrophobic polymer forming a separator, a hydrophilic compound forming a pore in the separator and remaining in the hydrophobic separator to impart hydrophilicity, and an antibacterial agent. As the hydrophobic polymer, polysulfone polymer, polyacrylic polymer, polycarbonate, halogen polymer and the like can be used. More specifically, polysulfone (Polysulfone), polyethersulfone (PES, Polyethersulfone), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polytetrafluoroethane (PTFE) may be used. As the hydrophilic compound, vinylpyrrolidone-based polymers, polyglycols, and the like are used. It is preferable to use those having a molecular weight of 10,000 or more so as to remain much in the hollow fiber membranes. It is preferable to use polyethylene glycol, polyvinyl alcohol, etc. as polyglycol, and polyvinylpyrrolidone etc. as vinylpyrrolidone type polymer.

As an antimicrobial agent for imparting antimicrobial properties, generally known organic antimicrobial agents or inorganic antimicrobial agents can be used. To be applied to the hollow fiber membrane, the stability in the membrane manufacturing process, compatibility with the material of the hollow fiber membrane, influence on the properties of the membrane, durability, dispersibility, etc. should be considered.

Organic antimicrobial agents have many types and excellent effects, but have limited use due to problems in safety (toxicity and environmental problems). In particular, when used for the membrane for water purification should be selected to be harmless to the human body. Organic antimicrobial agents that can be used in the present invention include organic copper compounds, organic zinc compounds, other organometallic compounds and chlorine phenyl ether compounds, organic nitrogen compounds, organosilicon quaternary ammonium, and the like, and more specifically, Isothiazolin-based compounds of (I), pyrithione-based metal compounds of the general formula (II) and the like can be used.

(Ⅰ)

In the formula (I), R ₁ , R ₂ and R ₃ are H, Cl or an alkyl group.

(Ⅱ)

In the formula (II), Me is a metal ion.

In the case of inorganic antimicrobial agents, inorganic carriers such as zeolite and silica alumina are substituted with metal ions having excellent antimicrobial properties such as silver, copper, and zinc. Generally, the average particle diameter is several microns or more and the particle size distribution is wide. Mixing and spinning in a fine hollow fiber membrane may cause the risk of cutting off. Therefore, in case of using inorganic antimicrobial agent, the product with small average particle diameter should be selected and used. As the inorganic antimicrobial agent, silver zeolite, which is generally used, can be used.

In the present invention, the amount of the antimicrobial agent remaining in the antimicrobial hollow fiber membrane is suitably 0.01 to 3% by weight relative to the total weight of the hollow fiber membrane. If the content of the antimicrobial agent is higher than this, the amount of the antimicrobial agent harmful to the human body is increased, and there is a risk of causing problems depending on the intended use.

The antimicrobial hollow fiber membrane manufacturing method of the present invention can be largely divided into two types, the spinning dope and the internal coagulating solution composed of hydrophobic polymer, organic solvent and hydrophilic compound are spun into the air with a double tubular nozzle and then solidified with external coagulant. When preparing the hollow fiber membrane, it can be divided into adding an antimicrobial agent to the spinning dope and adding an antimicrobial agent to the internal coagulation (core). A feature of the antimicrobial hollow fiber membrane manufacturing method of the present invention is that the antimicrobial agent is directly added to the spinning stock solution in order to fix the antimicrobial agent to the hollow fiber membrane. When the antimicrobial agent is added directly at the time of manufacture of the spinning stock solution, there is no process added to the film preparation, so the manufacturing process is very simple. In addition, since the dispersibility of the antimicrobial agent is improved, and finally the antimicrobial agent is strongly adhered to the hydrophobic polymer forming the membrane, the antimicrobial agent is not washed out in the permeated water when the membrane is used. When the antimicrobial agent is washed off in the permeate, the residual antimicrobial content of the membrane is lowered, so that the antimicrobial activity of the membrane is lowered, and the antimicrobial agent harmful to the human body is included in the permeate and there is a risk of causing problems when used in the hollow fiber membrane for water purifier. In the antimicrobial hollow fiber membrane prepared by the production method of the present invention, the residual antimicrobial content in the hollow fiber membrane was maintained at 70% or more of the initial content until after 5,000 L / m ² permeation of the general tap water.

First, when the antimicrobial agent is added to the spinning dope, the hydrophobic polymer forming the film is dissolved in an organic solvent, and then the hydrophilic compound and the antimicrobial agent are added thereto to prepare a spinning dope. In order to add the antimicrobial agent directly in the manufacture of the spinning dope, the antimicrobial agent must be stably dissolved in the spinning dope. In the present invention, for this purpose, the manufacturing temperature of the spinning dope is set to 40 to 140 ℃, when the manufacturing temperature of the spinning dope is 40 ℃ or less, the stability of the spinning dope is lowered, the transparency is lowered, when the hydrophilic compound or antimicrobial agent is 140 ℃ or more It causes denaturation and changes the final physical properties of the hollow fiber membranes. In order to evaluate the stability of the radiation dope was measured the absorbance of the radiation dope, it was determined that the absorbance at the wavelength of 450nm or less when measured by UV-VIS spectrophotometer (0.5) or less. As the organic solvent, m-cresol, chlorobenzene, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide and / or mixtures thereof are used. The content of the polymer constituting the spinning dope is 10-25% by weight, and the total content of the hydrophilic compound is 10-25% by weight. In the present invention, the antimicrobial agent was mixed with 0.01 to 5% by weight of the spinning dope to prepare a spinning dope. If it is used at 0.01% by weight or less, the desired antimicrobial effect could not be obtained. If it is used at 5% by weight or more, particles precipitate in the dope, causing cutting during spinning and affecting the uniformity of the hollow fiber membrane. As the internal coagulating solution, a mixture of the organic solvent and the nonsolvent or a mixture of the nonsolvent or the nonsolvent is used. As the non-solvent, water, alcohols, glycols and the like can be used, in particular ethyl alcohol, diethylene glycol, water and the like. Next, the spinning dope and the internal coagulating solution are spun into the air by using a conventional double tubular nozzle, and solidified in the external coagulating solution to form a membrane structure, washed with water, and then dried to prepare a hollow fiber membrane having antibacterial properties. do.

When an antimicrobial hollow fiber membrane is prepared by adding an antimicrobial agent to an internal coagulation solution (core), the hydrophobic polymer and the hydrophilic compound forming the membrane are dissolved in an organic solvent to prepare a spinning dope, and then the anticoagulant and powder are added to the internal coagulation solution. Internal coagulating solution is prepared by adding a metal salt for increasing acidity. Since the hollow fiber membranes that require antimicrobial properties are used in applications where fouling resistance or durability is a problem, most of the structures have a dense structure on the outer surface and have an asymmetric structure inside serving as a support layer. When preparing a membrane having such a structure, when the antimicrobial agent is mixed with the internal coagulating solution, the antimicrobial agent is firmly fixed to the inside of the membrane while moving from the inside of the membrane to the outside in the process of forming the membrane. In order to apply the antimicrobial agent to the hollow fiber membrane, the stability in the membrane manufacturing process, compatibility with the material of the hollow fiber membrane, the effect on the properties of the membrane, durability, dispersibility, etc. should be considered. Since the antimicrobial agent generally does not dissolve in the solution used as the internal coagulating solution, the antimicrobial agent is present in a dispersed phase. When the size of the dispersed particles is large, the antimicrobial agent is inferior in radioactivity and disadvantageous for uniform film production. Therefore, in the present invention, in order to increase the dispersibility of the antimicrobial agent, a metal salt having an effect of increasing the solubility in water was used. Alkali metal salts or alkaline earth metal salts may be used as the metal salt. The metal salt is preferably added to the internal coagulation solution so that the content of the alkali metal salt or alkaline earth metal salt contained in the internal coagulation solution composition solution is 0.01-5% by weight. In the present invention, the anticoagulant was mixed with the internal coagulation solution in an amount of 0.01 to 5% by weight to prepare an internal coagulation solution. In the case of using less than 0.01% by weight, the target antibacterial effect could not be obtained, when using more than 5% by weight, the dispersibility is inferior. Next, the spinning dope and the inner coagulating solution are spun into the air by using a conventional double tubular nozzle, and the coagulated liquid is formed in the outer coagulating solution to form a membrane structure, washed with water, wound up and dried to produce a hollow fiber membrane having antibacterial properties. do.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited only to the following examples.

Example 1

16% by weight of polysulfone resin (P-3500: Amoco Co., Ltd.), 11% by weight of polyvinylpyrrolidone, 4% by weight of polyethylene glycol, and 1% by weight of zinc pyridinethiol compound (Zinc Omadine: manufactured by OLIN) 68 wt% of acetamide was added, followed by stirring and dissolution to prepare a transparent spinning dope. The manufacturing temperature of spinning dope was 80 degreeC. The internal coagulation solution was prepared by adding 70% by weight of diethylene glycol to 30% by weight of water. The spinning dope and the internal coagulating solution were spun into air through a conventional double-tubular nozzle, and coagulated in a coagulation bath with an external coagulating solution, followed by washing and winding to prepare a hollow fiber membrane. At this time, water was used as the external coagulant. The prepared hollow fiber membrane was bundled and dried so as to have a membrane area of 0.5 m ² , placed in an ABS material case, and potted using a polyurethane adhesive to prepare a module.

Example 2

16 wt% of polysulfone resin (P-3500: Amoko Co., Ltd.), 11 wt% of polyvinylpyrrolidone, and 4 wt% of polyethylene glycol were added to 69 wt% of dimethylacetamide, followed by stirring and dissolving. Prepared. The internal coagulation solution was prepared by adding 69% by weight of diethylene glycol and 1% by weight of a zinc pyridinethiol compound (Zinc Omadine: manufactured by OLIN) as an antibacterial agent to 30% by weight of a 0.1 mole LiBr aqueous solution. The spinning dope and the internal coagulating solution were spun into air through a conventional double tubular nozzle, and coagulated in a coagulation bath with an external coagulating solution, followed by washing and winding to prepare a hollow fiber membrane. At this time, water was used as the external coagulant. The prepared hollow fiber membrane was bundled and dried to have a membrane area of 0.5 m 2, put in a case made of ABS material, and potted using a polyurethane adhesive to prepare a module.

Comparative Example 1

A hollow fiber membrane and a module were prepared in the same manner as in Example 1, except that 69 wt% of dimethylacetamide was added without adding zinc pyridinethiol compound (Zinc Omadine: manufactured by OLIN) as an antimicrobial agent. .

Comparative Example 2

Hollow fiber membrane and module in the same manner as in Example 2 except for using the internal coagulation solution (containing no antibacterial agent) prepared by adding 70% by weight of diethylene glycol to 30% by weight of water instead of the internal coagulation solution of Example 2. Was prepared.

Experimental Example 1 Antibacterial Activity and Remaining Antibiotic Test

The antimicrobial activity and content of the remaining antimicrobial agent of the prepared hollow fiber membrane was evaluated as follows. The hollow fiber module was filled with raw water (1,500 CFU / ml) and incubated in a 37 ° C. incubator for 24 hours, and then the general bacterial concentration of the filling was measured. Residual antimicrobial content was measured by using an element absorber to determine the content of metal ions included in the antimicrobial agent. The measurement results are shown in Table 1. The hollow fiber membrane containing the antimicrobial agent decreased the number of bacteria, but the membrane without the antimicrobial agent showed that the bacteria proliferated.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Residual Antibiotic Content (%) 0.81 0.77 0 0 General bacterial concentration (CFU / ml) 33 25 15,100 14,690

Experimental Example 2 Cumulative Flow Rate Test

The hollow fiber module prepared above was subjected to a water permeation test at a pressure of 1 kg / cm 2 to compare the instantaneous flow rates when the cumulative flow rate reached 5,000 liters. In the case of the membrane containing the antimicrobial agent, the instantaneous flow rate is excellent due to the anti-microbial effect, but it can be seen that the instantaneous flow rate is reduced in the membrane without the antimicrobial agent.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Instantaneous flow rate (L / min) 2.73 2.90 0.61 0.63

Experimental Example 3 Radioactive and Radiation Doping Characteristic Test

We compared and evaluated the radioactivity and spinning dope characteristics of hollow fiber manufacturing. Radiation dope properties were measured by using a UV-VIS spectrophotometer (absorbance at wavelength 450nm), which is used as a reference indicating the stability of the radiation dope.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Antibacterial content (%) 0.81 0.77 0 0 Radiation dope absorbance (450nm) 0.054 0.061 0.048 0.047 Cut-off frequency (times / 10 ⁶ m) 0 0.01 0 0

Experimental Example 4: residual antimicrobial test

The durability of the antimicrobial agent was evaluated by comparing the content of the antimicrobial agent in the hollow fiber membrane before and after the cumulative flow rate test of Experimental Example 2. It can be seen that the high temperature in the preparation of the spinning dope strengthens the physicochemical bond between the antimicrobial agent and the polymer forming the film, thereby preventing the dissolution of the antimicrobial agent in the use of the final product, thereby having a continuous antimicrobial effect.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Antibacterial content (%) before cumulative flow test 0.8 0.77 0 0 Antibacterial content (%) after cumulative flow rate test 0.73 0.67 0 0 Antimicrobial Retention Rate (%) 91.3 87.0 0 0

The hollow fiber membranes prepared according to the method of the present invention have excellent antibacterial properties, significantly improved bactericidal properties compared to the conventional separation membranes, and have excellent fouling resistance, thereby extending the service life. Therefore, the antimicrobial hollow fiber membrane of the present invention is useful for household water purifiers, industrial and medical water purifiers that require excellent bacteria removal performance and a large amount of permeation.

Claims (13)

In the hollow fiber membrane for microfiltration or ultrafiltration, the antimicrobial agent is contained in the hollow fiber membrane, and the residual antimicrobial content in the hollow fiber membrane is 70% or more of the initial antimicrobial agent content after 5,000 L / m ² permeation of general tap water. The antimicrobial hollow fiber membrane according to claim 1, wherein the content of the antimicrobial agent in the hollow fiber membrane is 0.01 to 3% by weight. The antimicrobial hollow fiber membrane according to claim 1 or 2, wherein the antimicrobial agent is an organic antimicrobial agent or an inorganic antimicrobial agent. The organic antimicrobial agent is an organic copper compound, an organic zinc compound, a chlorine phenyl ether compound, an organic nitrogen compound, an organosilicon quaternary ammonium, an isothiazolin compound, or a pyrithione metal compound. Or antimicrobial hollow fiber membrane, characterized in that a mixture thereof. The antimicrobial hollow fiber membrane according to claim 3, wherein the inorganic antimicrobial agent is a metal ion substituted with an inorganic carrier. The antimicrobial hollow fiber membrane according to claim 3 or 5, wherein the inorganic antimicrobial agent is silver zeolite, copper zeolite, zinc zeolite, silver silica alumina, zinc silica alumina or a mixture thereof. In the manufacturing of the hollow fiber membrane by spinning the spinning dope and the internal coagulating solution composed of a hydrophobic polymer, an organic solvent, and a hydrophilic compound into the air with a double tubular nozzle and then coagulating with the external coagulating solution, an antimicrobial agent is added to the spinning dope. Method for producing an antimicrobial hollow fiber membrane, characterized in that. The method of claim 7, wherein the content of the antimicrobial agent in the spinning dope is 0.01 to 5% by weight. The method for producing an antimicrobial hollow fiber membrane according to claim 7, wherein the radiation dope containing the antimicrobial agent is measured at a wavelength of 450 nm using a UV-VIS spectrophotometer. In the manufacture of the hollow fiber membrane by spinning the spinning dope and the internal coagulating solution composed of a hydrophobic polymer, an organic solvent and a hydrophilic compound into the air with a double tubular nozzle, and then coagulating with the external coagulating solution, the addition of an antimicrobial agent to the internal coagulating solution. Method for producing an antibacterial hollow fiber, characterized in that. The method for producing an antimicrobial hollow fiber membrane according to claim 10, wherein the amount (content) of the antimicrobial agent in the internal coagulating solution is 0.01-5% by weight. The method for producing an antimicrobial hollow fiber membrane according to claim 10, wherein an alkali metal salt or an alkaline earth metal salt is contained in the internal coagulating solution composition. The method for producing an antimicrobial hollow fiber membrane according to claim 10, wherein the content of the alkali metal salt or alkaline earth metal salt contained in the internal coagulating solution composition is 0.01-5% by weight.