Patent Grant
8684188
This is the U.S. national phase application of International Application No. PCT/JP2009/001656, filed Apr. 9, 2009, which claims the benefit of Japanese patent application No. 2008-104036, filed Apr. 11, 2008.
The present invention relates to a hydrophilic filtration membrane made from a polyethersulfone, a process for production, and a dope solution. More particularly, the present invention relates to a hydrophilic filtration membrane made from a polyethersulfone, and a process for production of the same and a dope solution suited for use in the field of water treatments involving beverage (drinking water) manufacturing, water purification treatment and waste water treatment, as well as medical field, food engineering field, and the like.
In recent years, filtration membranes (separation membranes) are utilized in a variety of areas such as the field of water treatments involving beverage manufacturing, water purification treatment and waste water treatment, as well as food industry field, and the like. Filtration membranes have been utilized for eliminating impurities in water as an alternative to conventional sand filtration or coagulating sedimentation process in the field of water treatments involving beverage manufacturing, water purification treatment, waste water treatment and the like. Moreover, in the food engineering field, filtration membranes have been utilized for the purpose of concentrating liquids, and separating and eliminating yeast etc., used in fermentation.
Since the quantity of treated water with filtration membranes used in various ways as described above is large in the field of water treatments such as water purification treatment and waste water treatment, improvement of water permeability has been demanded. Superior water permeability enables the membrane area to be decreased, and thus compact apparatuses can be provided to permit cost reduction of equipment, leading to advantages in terms of costs for replacing the membrane as well as the area of equipment.
Additionally, in waste water treatments, a microbicide such as sodium hypochlorite is charged into a membrane module portion for the purpose of sterilizing charged water and preventing biofouling of the membrane. Furthermore, since the membrane itself is washed with an acid, an alkali, chlorine, a surfactant etc., filtration membrane requires chemical resistance properties.
Moreover, in production of tap water, troubles of contamination of treated water with pathogenic microorganisms that are resistant to chlorine such as cryptosporidium, derived from feces and urine of livestocks and the like are not dealt with in a water purifying plant have elicited since 1990s. Thus, for preventing such troubles, sufficient separation characteristics so as to avoid contamination of treated water with the raw water, and great physical strength have been required for filtration membranes.
Therefore, filtration membranes require superior blocking performance, chemical resistance, physical strength, water permeability and fouling resistance. Thus, filtration membranes produced using a polyvinylidene fluoride based resin having both chemical resistance and physical strength in combination have been used. However, since filtration membranes produced using a polyvinylidene fluoride based resin is hydrophobic, fouling substances are likely to be attached to pores of the filtration membrane, and thus washing with a chemical such as sodium hypochlorite must be frequently carried out. Therefore, lifetime of the membrane is shortened, and the frequency of replacement of the membrane is increased, leading to a problem of high running costs. In addition, since filtration membranes produced using a polyvinylidene fluoride based resin contain halogen molecules, environmental endocrine disrupters are generated upon incineration for disposal, which may lead to problems of great environmental burden.
On the other hand, cellulose based resins have attracted attention in addition to polyvinylidene fluoride based resins. Cellulose based resins are more hydrophilic as compared with polyvinylidene fluoride, and is advantageous in high fouling resistance. Additionally, since halogen is not contained, it is advantageous in less environmental burden. However, it is disadvantageous in low physical strength.
Furthermore, a polyethersulfone (hereinafter, may be abbreviated as “PES”) is noteworthy as a compound that exhibits intermediate characteristics of polyvinylidene fluoride based resins and cellulose based resins in both terms of physical strength and fouling resistance (for example, see Patent Documents 1 to 3). However, even when a polyethersulfone is used as a filtration membrane, hydrophilicity of the membrane itself is still insufficient, and a filtration membrane which is satisfactory in light of fouling resistance has not been obtained under current circumstances.
An object of the present invention is to provide a hydrophilic filtration membrane that is superior in blocking performance, chemical resistance, physical strength and water permeability, and is also superior in fouling resistance.
The hydrophilic filtration membrane made from a polyethersulfone of the present invention is characterized by containing a hydrophilic polyethersulfone having a contact angle of 65 to 74 degree. In other words, hydrophilization of the hydrophilic polyethersulfone in the present invention is permitted by, for example, introduction of a hydroxy group at the end of a polyethersulfone or the like.
The number of hydroxy groups in the hydrophilic polyethersulfone is preferably 0.6 to 1.4 per 100 polymerization repeating units. Furthermore, the hydrophilic polyethersulfone has a molecular weight of preferably in the range of 10,000 to 100,000.
The hydrophilic filtration membrane of the present invention may further contain a polyvinylpyrrolidone (poly(N-vinyl-2-pyrrolidone)). Herein, the polyvinylpyrrolidone used in the present invention preferably has a molecular weight in the range of 10,000 to 1,300,000.
Since a hydrophilic polyethersulfone is used in the hydrophilic filtration membrane of the present invention, compatibility of the polyvinylpyrrolidone with the polyethersulfone is improved, whereby the polyvinylpyrrolidone that is intrinsically water soluble is not easily eluted from the filtration membrane. In other words, since a hydrophilic compound has not been used as the polyethersulfone in producing conventional filtration membranes, a polyvinylpyrrolidone is not compatible with a polyethersulfone, and has been merely added as a pore-opening agent for forming holes by allowing for elution during membrane production, as disclosed in Patent Document 1 described above. On the other hand, in the present invention, the polyvinylpyrrolidone is miscible with the hydrophilic polyethersulfone and retained in the filtration membrane, whereby a function of significantly improving hydrophilicity of the filtration membrane is undergone.
The dope solution of the present invention is characterized by containing the aforementioned hydrophilic polyethersulfone having a contact angle of 65 to 74 degree, and a solvent. The number of hydroxy groups in the hydrophilic polyethersulfone is preferably 0.6 to 1.4 per 100 polymerization repeating units, and the molecular weight is preferably in the range of 10,000 to 100,000.
Moreover, the solvent in the dope solution of the present invention is preferably an organic solvent that allows the hydrophilic polyethersulfone to be dissolved, and is miscible with water.
The dope solution of the present invention may further contain a polyvinylpyrrolidone (poly(N-vinyl-2-pyrrolidone)) in order to improve hydrophilicity of the resultant filtration membrane. This polyvinylpyrrolidone preferably has a molecular weight in the range of 10,000 to 1,300,000. The solvent in the dope solution of the present invention is preferably an organic solvent that allows the hydrophilic polyethersulfone to be dissolved, and is miscible with water, and is more preferably an organic solvent that allows the hydrophilic polyethersulfone and the polyvinylpyrrolidone to be dissolved, and is miscible with water.
The process for producing the hydrophilic filtration membrane of the present invention is characterized in that a filtration membrane is obtained by a nonsolvent-induced phase separation process using the aforementioned dope solution. More specifically, the solvent of the dope solution is removed by pouring the dope solution poured into a membrane production bath solution that serves as a nonsolvent for the hydrophilic polyethersulfone to form a porous membrane. The membrane production bath solution is preferably water in light of the cost and the like; therefore, the solvent of the dope solution is preferably an organic solvent that allows the hydrophilic polyethersulfone, to be dissolved and is miscible with water.
In the process for producing the hydrophilic filtration membrane of the present invention, a hydrophilic filtration membrane in the form of a flat membrane is obtained by discharging the dope solution from above the liquid level or into the liquid of the membrane production bath solution to give a form of a membrane using a discharge nozzle. Alternatively, a hydrophilic filtration membrane in the form of a hollow fiber membrane is obtained by discharging the dope solution from above the liquid level or into the liquid of the membrane production bath solution to give a hollow fiber form using a multi-discharge nozzle, and concurrently discharging an internal diameter-maintaining liquid from the center section of the multi-discharge nozzle into the center section of the hollow fiber.
Additionally, in the process for producing the hydrophilic filtration membrane of the invention of the present application, the hydrophilic filtration membrane is preferably reinforced with a reinforcing fiber. Namely, in the case of a hydrophilic filtration membrane in the form of a flat membrane, the intended membrane is obtained by discharging a dope solution together with a reinforcing fiber into a membrane production bath solution upon discharging the dope solution into a form of a membrane. Alternatively, in the case of a hydrophilic filtration membrane in the form of a hollow fiber membrane, the intended membrane is obtained by discharging a dope solution together with a hollow reinforcing fiber from above the liquid level or into the liquid of the membrane production bath solution.
The hydrophilic filtration membrane of the present invention is one that is superior in the physical strength and chemical resistance, and also has high fouling resistance, since a hydrophilic polyethersulfone prepared to be hydrophilic while maintaining various characteristics of the polyethersulfone is used. In particular, the hydrophilic filtration membrane strengthened using a reinforcing fiber becomes extremely superior in light of the physical strength.
Additionally, since the hydrophilic filtration membrane containing a polyvinylpyrrolidone of the present invention has high compatibility of the polyvinylpyrrolidone with the hydrophilic polyethersulfone, the polyvinylpyrrolidone is likely to remain in the filtration membrane without elution from the filtration membrane even during the membrane production, leading to significant increase of the hydrophilicity of the filtration membrane, and thus a filtration membrane that is superior in fouling resistance can be obtained. Therefore, by using the hydrophilic filtration membrane of the present invention, the frequency of washing of the separation membrane decreases, and product life time is prolonged. Thus, providing an innovative technique for producing a separation membrane that achieves low running costs is enabled.
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Embodiments of the present invention will be explained below, but the present invention is not limited to the following embodiments.
In the present invention, a hydrophilic polyethersulfone having a contact angle of 65 to 74 degree, preferably a contact angle of 65 to 70 degree is used as the polyethersulfone. In general, a polyethersulfone has a contact angle of 85 to 90 degree, and the hydrophilic polyethersulfone having such a small contact angle as described above is produced by, for example, introducing a hydroxy group into the end of a polyethersulfone. As such a hydrophilic polyethersulfone, “SUMIKA EXCEL 5003PS” (manufactured by Sumitomo Chemical Co., Ltd.) may be exemplified.
The number of hydroxy groups in the hydrophilic polyethersulfone is preferably 0.6 to 1.4 per 100 polymerization repeating units, and more preferably in the range of 0.8 to 1.2. When the number of hydroxy groups is less than 0.6 per 100 polymerization repeating units, hydrophilicity of the filtration membrane is lowered to deteriorate the fouling resistance. In addition, a polyethersulfone having the number of hydroxy groups of greater than 1.4 per 100 polymerization repeating units is inferior in chemical stability upon treatments such as cleaning with a chemical.
Moreover, the hydrophilic polyethersulfone has a molecular weight of preferably in the range of 10,000 to 100,000, and more preferably in the range of 40,000 to 80,000. When the molecular weight is lower than 10,000, physical strength of the filtration membrane becomes deficient, leading to difficulty in membrane production. Whereas, those having a molecular weight of higher than 100,000 are hardly available in substance.
The hydrophilic filtration membrane of the present invention may further contain a polyvinylpyrrolidone (poly(N-vinyl-2-pyrrolidone)). The molecular weight of the polyvinylpyrrolidone is preferably in the range of 10,000 to 1,300,000, and more preferably in the range of 40,000 to 800,000. The molecular weight of the polyvinylpyrrolidone being lower than 10,000 is not appropriate since the polyvinylpyrrolidone is more likely to be eluted, and a phenomenon of forming air holes of the membrane occurs. Whereas, those having a molecular weight of higher than 1,300,000 are hardly available in substance.
When the filtration membrane contains the polyvinylpyrrolidone, the content is up to 200 parts by weight, and preferably up to 150 parts by weight relative to 100 parts by weight of the hydrophilic polyethersulfone. The content exceeding 200 parts by weight is not preferred since the strength as a filtration membrane cannot be maintained.
The dope solution of the present invention contains the aforementioned hydrophilic polyethersulfone having a contact angle of 65 to 74 degree, and a solvent. It is necessary that the solvent in the dope solution allows the hydrophilic polyethersulfone to be dissolved, and is miscible with a nonsolvent in the membrane production bath solution for use in producing the filtration membrane. In particular, when the membrane production bath solution containing water is used, the solvent in the dope solution must be an organic solvent that allows the hydrophilic polyethersulfone to be dissolved, and is miscible with water. Examples of such a solvent include dimethylsulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylformamide (DMF), and dimethylacetamide (DMAc).
Furthermore, the dope solution of the present invention may further contain the aforementioned polyvinylpyrrolidone. When the polyvinylpyrrolidone is blended, the solvent must allow not only the hydrophilic polyethersulfone but also the polyvinylpyrrolidone to be dissolved. Examples of such a solvent include dimethylsulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc).
The concentration of the hydrophilic polyethersulfone in the dope solution of the present invention is preferably in the range of 5 to 40% by weight, and more preferably in the range of 15 to 25% by weight. Furthermore, when the dope solution contains the polyvinylpyrrolidone, the concentration of the polyvinylpyrrolidone is preferably in the range of 1 to 15% by weight, and more preferably in the range of 5 to 10% by weight.
Still further, to the dope solution of the present invention may be added a pore-opening agent for forming through-holes during the production of the filtration membrane by eluting into the membrane production bath solution. Illustrative examples of such a pore-opening agent include polyethylene glycol (PEG 200 to PEG 4000), and the like.
Also, to the dope solution of the present invention may further added an inorganic salt such as LiCl, as well as a surfactant such as a polyoxyethylene-polyoxypropylene surface active block copolymer (trade name Pluronic F-127, Basf Japan Ltd.). These additives have effects of changing the electrical state of the dope solution, and concomitantly enhancing the amount of water permeation and the physical strength of the membrane in the production of the membrane.
The process for producing the hydrophilic filtration membrane of the present invention employs a nonsolvent-induced phase separation process. More specifically, the filtration membrane is obtained by charging the dope solution into a membrane production bath solution to be a nonsolvent for the hydrophilic polyethersulfone. Herein, it is necessary to use a membrane production bath solution which is a nonsolvent for the hydrophilic polyethersulfone, namely, which does not allow the hydrophilic polyethersulfone to be dissolved, and which is miscible with the solvent contained in the dope solution. When the aforementioned dimethylsulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc) or the like is used as the solvent of the dope solution, a membrane production bath solution containing water may be used as the membrane production bath solution. In light of the cost and the like, the membrane production bath solution is more preferably water.
The hydrophilic filtration membrane of the present invention can improve the physical strength by using a reinforcing fiber. The reinforcing fiber which may be used includes a glass fiber, a synthetic fiber, a semisynthetic fiber, a natural fiber or the like.
When the hydrophilic filtration membrane of the present invention is produced in the form of a flat membrane, a die or the like is used to discharge the aforementioned dope solution from above the liquid level or into the liquid of the membrane production bath solution using a discharge nozzle to give a form of a membrane, whereby a flat membrane is obtained. Accordingly, the solvent in the dope solution is removed into the membrane production bath solution, and as a result, the hydrophilic polyethersulfone insoluble in the membrane production bath solution is left as a porous filtration membrane. A hydrophilic filtration membrane in the form of a membrane reinforced with a reinforcing fiber can be obtained by feeding the reinforcing fiber concomitantly with discharging the dope solution in parallel from the discharge nozzle.
The hollow fiber membrane composed of the hydrophilic filtration membrane is produced according to the nonsolvent-induced phase separation process, by discharging the dope solution from above the liquid level or into the liquid of the membrane production bath solution to give a hollow fiber form using a multi-discharge nozzle, and concomitantly discharging an internal diameter-maintaining liquid from the center section of the multi-discharge nozzle to the center section of the hollow fiber. The internal diameter-maintaining liquid is used for allowing the hollow fiber membrane to maintain a hollow shape. As this internal diameter-maintaining liquid, a liquid similar to the membrane production bath solution may be used. The hydrophilic filtration membrane in the form of a hollow fiber reinforced using the reinforcing fiber is obtained without using the internal diameter-maintaining liquid, by discharging the dope solution from above the liquid level or into the liquid of the membrane production bath solution together with a hollow reinforcing fiber.
Production of the hollow fiber membrane according to a nonsolvent-induced phase separation process is conducted generally using a spinning apparatus as shown in
As shown in
The hollow fiber membrane 10 formed by nonsolvent-induced phase separation in the membrane production bath solution 7 is wound by a winding unit 8 (see,
The hollow fiber membrane reinforced with the reinforcing fiber can be manufactured using an apparatus illustrated in the schematic configuration diagram shown in
A hydrophilic polyethersulfone (SUMIKA EXCEL 5003PS, manufactured by Sumitomo Chemical Co., Ltd., contact angle: 65 to 74 degree, number of hydroxy groups per 100 polymerization repeating units=0.89) was added to dimethylsulfoxide (manufactured by Wako Pure Chemical Industries, Ltd.) such that its concentration became 15% by weight, and the mixture was stirred for 24 hrs using a stirrer or the like to prepare a sufficiently homogenous solution. Thereafter, the mixture was maintained for 24 hrs, and the bubbles in the solution were sufficiently removed to obtain a dope solution.
This dope solution was used to conduct spinning of a hollow fiber membrane under conditions shown in Table 1 with the spinning apparatus shown in
A hollow fiber membrane of industrially available polyvinylidene fluoride (PVDF) was employed as Comparative Example 1.
A hydrophilic polyethersulfone (SUMIKA EXCEL 5003PS, manufactured by Sumitomo Chemical Co., Ltd.) and a polyvinylpyrrolidone (K30 (manufactured by Wako Pure Chemical Industries, Ltd.), molecular weight: 40,000) were added to dimethylsulfoxide (manufactured by Wako Pure Chemical Industries, Ltd.) such that their concentrations became 15% by weight and 1.25% by weight, respectively, to obtain dope solutions in a similar manner to Example 1.
Using this dope solution, a hollow fiber membrane was spun with the spinning apparatus shown in
A dope solution and a hollow fiber membrane were obtained by conducting a similar operation to that in Example 2 except that a usual polyethersulfone (E6020P, manufactured by BASF Japan Ltd., molecular weight: 50,000, contact angle: 85 to 90 degree, number of hydroxy groups per 100 polymerization repeating units=0) was used in place of the hydrophilic polyethersulfone.
A dope solution and a hollow fiber membrane were obtained by conducting a similar operation to that in Example 2 except that a polyvinylpyrrolidone (K90, (manufactured by Wako Pure Chemical Industries, Ltd.), molecular weight: 360,000) in an amount of 5% by weight was used in place of the polyvinylpyrrolidone (K30).
A dope solution and a hollow fiber membrane were obtained by conducting a similar operation to that in Example 3 except that a usual polyethersulfone (E6020P, manufactured by BASF Japan Ltd.) was used in place of the hydrophilic polyethersulfone.
A hydrophilic polyethersulfone (SUMIKA EXCEL 5003PS, manufactured by Sumitomo Chemical Co., Ltd.) and LiCl were dissolved in dimethylsulfoxide to give the concentrations of 15% by weight and 2% by weight, respectively, and a dope solution was obtained in a similar manner to Example 1. Using this dope solution, a hollow fiber membrane reinforced with a strong fiber substance was manufactured with the apparatus shown in
A dope solution was obtained in a similar manner to Example 1 except that a hydrophilic polyethersulfon and LiCl were dissolved in dimethylsulfoxide to give the concentrations of 12.5% by weight and 2% by weight, respectively. Using this dope solution, a hollow fiber membrane reinforced with the strong fiber substance was obtained in a similar manner to Example 4 with the apparatus shown in
A hollow fiber membrane strengthened with the fiber was obtained in a similar manner to Example 5 except that the winding speed of the winding unit 25 was changed to 0.03 m/sec.
(Fouling Resistance Test)
A fouling resistance test was conducted using the hollow fiber membrane of Example 1 and Comparative Example 1.
A fouling resistance test was conducted using the apparatus having the aforementioned construction. To the sewage in the sewage vessel 35 was added 20 ppm humic acid as a fouling substance, and the temperature of the mixture was kept at 25 degree C. The flow rate of the sewage was kept constant at 2.8 mL/min. The sewage was allowed to flow from the outside of the hollow fiber membrane 31 for 10 min, and the filtered water that had permeated the hollow fiber membrane 31 was collected, and the transmembrane pressure difference of the hollow fiber membrane 31 then was measured using a data logger (manufactured by KEYENCE Corporation, NR-1000) In addition, the elimination rate of the humic acid was calculated from the contents of humic acid in the sewage and the filtered water. The content of humic acid was determined using a UV spectrophotometer (manufactured by Hitachi, Ltd., U-200).
Next, cleaning water (25 degree C.) containing 5 ppm sodium hypochlorite was allowed to flow at a constant flow rate of 5.6 mL/min for 3 min to carry out reverse cleaning.
The foregoing procedures of the filtration and the reverse cleaning were repeated until the transmembrane pressure difference became about 150 kPa, and the results are shown in
As is clear from
The fouling substance accumulation rates of the hollow fiber membranes of Example 1 and Comparative Example 1 were 0.8 kPa/h and 2.4 kPa/h, respectively, showing extremely smaller fouling substance accumulation rate of the hollow fiber membrane in Example 1 as compared with the value of the hollow fiber membrane in Comparative Example 1.
(Observation of Hollow Fiber Membrane Using Scanning Electron Microscope)
In order to obtain a hollow fiber membrane in the dry state, the hollow fiber membranes of Examples 1, 3 and 4 in the wet state were freeze-dried with a freeze drying apparatus (manufactured by EYELA, FD-1000). Observation samples were prepared by vapor deposition of Au/Pd by sputtering on: the surface and the cross-sectional surface of the freeze-dried hollow fiber membrane subjected to brittle fracture in liquid nitrogen in the case of Examples 1 and 3; and the surface of the freeze-dried hollow fiber membrane in the case of Example 4. The surface and the cross-sectional surface were observed with a scanning electron microscope (manufactured by JEOL Ltd. DATUM, JSM-7000F) under an accelerating voltage of 5 kV, at an applied electric current of 0.8 A. Moreover, the hollow fiber membrane of Example 4 was embedded using an epoxy resin for embedding (manufactured by Refinetech Co., Ltd.) after the freeze-drying, and then cut and polished on the face perpendicular to the longitudinal direction. Accordingly, the cross-sectional surface was observed with a scanning electron microscope.
The electron micrographs of the cross-sectional surface and the surface of the hollow fiber membrane of Example 1 are shown in
In addition, the electron micrographs of the surface and the cross-sectional surface of the hollow fiber membrane of Example 4 are shown in
(Measurement of Contact Angle)
Using a contact angle measurement apparatus (manufactured by Kyowa Interface Science Co., LTD., DropMaster 300), contact angles of the polyethersulfone used in Examples 2 and 3, and Comparative Examples 2 and 3, as well as contact angles of water on the external surfaces of the hollow fiber membranes of Examples 2 and 3, and Comparative Examples 2 and 3 were measured. A droplet of 0.5 mL were placed dropwise on the external surface of the hollow fiber membrane using a certain injection needle, and the contact angle of the droplet was calculated by image processing using a camera attached to the apparatus. This operation was repeated 20 times for one sample, and the mean value of the 20-times measurement was determined as the contact angle of the sample. In order to avoid the measurement error due to permeation and evaporation of the droplet into the hollow fiber membrane, the time period between the placing of the droplet and the measurement by image processing was minimized to as short as possible. Table 2 shows the results of the measurement in connection with the performances of the hollow fiber membrane. These results reveal that the contact angles of the hollow fiber membranes of Examples 2 and 3 were lowered as compared with the contact angles of the hollow fiber membranes of Comparative Examples 2 and 3 which correspond to one another, suggesting that the polyvinylpyrrolidone remained in the membrane.
(Water Permeability Test)
The water permeability of the hydrophilic filtration membrane of the present invention was measured using the apparatus for testing the amount of water permeation illustrated in the schematic view shown in
A predetermined amount of ion exchanged water was allowed to flow from inside the hollow fiber membrane 53 via the injection needle 51a using the rotary pump 50 at a flow rate of 0.6 ml/min for 3 min to obtain filtered water. In this procedure, the ion exchanged water not filtered was allowed to flow out via the injection needle 51b from the opposite end. The flow rate of the filtered water was measured using an electronic balance, and the injection pressure and the discharge pressure of the membrane were measured with the pressure gauges 51 and 52, respectively. One sample of the hollow fiber membrane 53 was subjected to the measurement four times, and the mean value of the four-times measurement was determined as the amount of water permeation of the sample. The dimensions such as the internal diameter and the external diameter of the hollow fiber membrane were measured using a scanning electron microscope (SEM). The amount of water permeation was calculated using the dimensions (full length, internal diameter) of the membrane, the measurement time period (3 min), the injection pressure value and the discharge pressure value, and the flow rate of the filtered water.
(Strength Test (Measurement of Stress, Strain and Young's Modulus)
Measurement of the physical strength of the polyethersulfone hollow fiber membrane of the present invention was carried out using a precision universal testing machine (manufactured by Shimadzu Corporation, Autograph AGS-J series). After a polyethersulfone membrane having a length of 50 mm was provided and fixed with a zipper, a load was applied to give a constant cloth head speed of 50 mm/min, and the maximum stress and the strain were measured. Young's modulus was calculated by data processing soft ware (manufactured by Shimadzu Corporation, TRAPEZIUM 2) based on the slope of the load-displacement curve.
From the results shown in Table 2, it is revealed that any of the hollow fiber membranes of Examples 2 and 3, and Comparative Examples 2 and 3 had high water permeability, and particularly the hollow fiber membranes of Examples 4 to 6 strengthened with the reinforcing fiber had superior water permeability. In addition, the physical strength also reached a practically applicable level, and particularly the hollow fiber membranes of Examples 4 to 6 strengthened with the reinforcing fiber had significantly high physical strength.
According to the dope solution of the present invention, a filtration membrane having high chemical resistance, high strength, high water permeability and high blocking performance, and having superior fouling resistance is obtained. Therefore, the present invention is applicable in the fields such as water supply business, food engineering field, medical field such as artificial dialysis treatments, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-104036 | Apr 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/001656 | 4/9/2009 | WO | 00 | 12/20/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/125598 | 10/15/2009 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4061821 | Hayano et al. | Dec 1977 | A |
| 4822269 | Kamiyama et al. | Apr 1989 | A |
| 4900449 | Kraus et al. | Feb 1990 | A |
| 5178765 | Hu et al. | Jan 1993 | A |
| 5277812 | Hu et al. | Jan 1994 | A |
| 5472607 | Mailvaganam et al. | Dec 1995 | A |
| 5846428 | Martin et al. | Dec 1998 | A |
| 5885456 | Charkoudian et al. | Mar 1999 | A |
| 5891338 | Bell et al. | Apr 1999 | A |
| 5911880 | Klein et al. | Jun 1999 | A |
| 5942120 | Wilkinson | Aug 1999 | A |
| 6595043 | Jaye | Jul 2003 | B2 |
| 7347908 | Share et al. | Mar 2008 | B2 |
| 7641055 | Ferrer et al. | Jan 2010 | B2 |
| 7959808 | Yeager et al. | Jun 2011 | B2 |
| 20070199891 | Mabuchi et al. | Aug 2007 | A1 |
| 20080135481 | Steiger et al. | Jun 2008 | A1 |
| 20100108607 | Yeager et al. | May 2010 | A1 |
| 20100190965 | Yamaguchi et al. | Jul 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 1 875956 | Jul 2006 | EP |
| 52-081076 | Jul 1977 | JP |
| 5-082251 | Nov 1993 | JP |
| 07-163847 | Jun 1995 | JP |
| 2000-042384 | Feb 2000 | JP |
| 2002-512876 | May 2002 | JP |
| 2003-225542 | Aug 2003 | JP |
| 2006-081970 | Mar 2006 | JP |
| Entry |
|---|
| International Search Report and Written Opinion for corresponding International Application No. PCT/JP2009/001656, dated May 26, 2009. |
| Number | Date | Country | |
|---|---|---|---|
| 20110108478 A1 | May 2011 | US |
