Tubular filter membrane using stretched separation membrane and manufacturing method thereof

Abstract

The present invention relates to a tubular filter membrane using a stretched separation membrane and a method for manufacturing the same, and relates to a separation membrane for removing particulate matter in the flow of liquid and gas, particularly a tubular filter membrane mainly used in a concentration process or a process for treating raw water containing a large amount of sludge, to a tubular filter membrane using a stretched separation membrane, and to a method for manufacturing the same, and to a tubular filter membrane using a stretched separation membrane, particularly a tubular filter membrane mainly used in a concentration process or a process for treating raw water containing a large amount of sludge. The present invention relates to a separation membrane comprising an olefin-based or fluorine-based polymer having excellent physicochemical properties so as to introduce a more powerful cleaning method that prevents damage to the separation membrane due to cleaning when performing physical or chemical cleaning for preventing or solving contamination of the separation membrane resulting from the use of the separation membrane. Furthermore, in order to easily introduce a high-strength physical or chemical cleaning method into a tubular filter membrane, the present invention relates to a manufacturing method in which a separation membrane, which is manufactured using an olefin-based or fluorine-based polymer having excellent physicochemical properties by a stretching method, is introduced into a tubular filter membrane.

Description

Technical Field

[0001] The invention relates to a tubular filter membrane using a stretched separation membrane and a manufacturing method thereof. Background Art

[0002] Separation membrane technology is widely used in separation processes across various industrial fields. In each separation process, the separation membrane itself is not used independently. Instead, depending on the purpose and characteristics of the separation process being used, sheet-like separation membranes are usually configured into plate-frame, spiral, or pleated modules, while hollow straw-shaped separation membranes with a cylindrical structure are configured into hollow filament or tubular modules.

[0003] Separation membranes in the shape of hollow straws with a cylindrical structure are generally classified as hollow fiber membranes if they have a diameter of 3 mm or less and have fibrous properties, and as tubular membranes if they have a diameter of 8 mm or more and have a hard body. Depending on the separation membrane used, separation membranes with thousands to tens of thousands of hollow fiber membranes arranged in a collection tube are classified as hollow fiber modules, and separation membranes with a few to dozens of tubular membranes arranged are classified as tubular modules.

[0004] Compared with other modules, the advantage of hollow fiber modules is that they have the largest effective membrane area per unit volume, and therefore are widely used in various water treatment processes. In contrast, tubular modules use fewer separation membranes for module configuration, and the effective membrane area per unit volume of each separation membrane is also smaller. Therefore, they can only be used in limited areas where the characteristics of tubular filter membranes can be fully utilized.

[0005] Compared with hollow fiber membranes, the most notable feature of tubular filter membranes is their relatively large diameter. The large diameter of the tubular filter membrane can serve as a flow path for raw water, and has the advantage of being able to form good fluid flow. It can be used in processes where the raw water to be separated has a high viscosity or needs to be concentrated to a high viscosity, as well as in processes for treating raw water containing a large amount of sludge. As a stopgap measure to effectively remove pollutants (scaling or agglomeration layers) accumulated on the surface of the separation membrane during the separation process, various physical cleaning methods can be introduced, such as introducing air into the separation membrane, making soft materials such as sponge balls move back and forth, or rapidly changing the internal flow rate.

[0006] Another feature of the tubular filter membrane is its rigid body. This rigid body allows for use in harsh environments where there is a risk of membrane damage due to high flow rates, impurities, cleaning foam, etc. during the separation process. Furthermore, the membrane has the advantage of being able to introduce high-intensity physical cleaning methods to effectively remove scaling or agglomeration layers generated during the separation process.

[0007] As mentioned above, tubular membranes are specialized for use in concentration processes, raw water treatment processes involving large amounts of sludge, and separation processes under harsh environments. Therefore, they require more robust cleaning than other separation membrane modules. Their advantages are doubled when they are manufactured from materials with excellent physical and chemical properties, such as olefin-based polymers such as polyethylene (PE) and polypropylene (PP), or fluorine-based polymers such as polytetrafluoroethylene (PTFE).

[0008] However, in order to manufacture separation membranes using olefin-based or fluorine-based polymers that are insoluble in organic solvents, it is usually necessary to be able to manufacture them by thermally induced phase separation (TIPS) or stretching methods without using organic solvents. However, due to the limitation that tubular filter membranes must use a tubular support with a hard body, the separation layer is coated on a cylindrical support with a hard body by a non-solvent induced phase separation method (NIPS), or the separation layer is coated on a strip-shaped support by a non-solvent induced phase separation method (NIPS), and then the support is configured into a tubular shape for manufacturing. Olefin-based or fluorine-based polymers cannot be used for manufacturing.

[0009] Prior art literature

[0010] Patent Literature

[0011] KR10-0626342B1 Summary of the Invention

[0012] Technical issues to be solved

[0013] The object of the present invention is to provide a tubular filter membrane using a stretched separation membrane and a method for manufacturing the same.

[0014] Another object of the present invention is to provide a separation membrane for removing particulate matter in the flow of liquids and gases, particularly as a tubular filter membrane mainly used in a concentration process or a process for treating raw water containing a large amount of sludge, and to provide a tubular filter membrane using a stretched separation membrane, which contains an olefin-based or fluorine-based polymer with excellent physical and chemical properties, so that when physical or chemical cleaning is implemented to prevent or resolve contamination of the separation membrane caused by the use of the separation membrane, a more powerful cleaning method that prevents damage to the separation membrane caused by cleaning can be introduced.

[0015] Another object of the present invention is to provide a method for manufacturing a tubular filter membrane in order to easily introduce high-intensity physical or chemical cleaning methods into the tubular filter membrane, which introduces a separation membrane manufactured by a stretching method using an olefin-based or fluorine-based polymer with excellent physical and chemical properties into the tubular filter membrane, thereby further enhancing the advantages of the tubular filter membrane.

[0016] Technical solutions to technical issues

[0017] To achieve the above object, the tubular filter membrane using a stretched separation membrane of the present invention comprises a porous tubular support and a stretched separation membrane. The stretched separation membrane can be manufactured using an olefin-based polymer or a fluorine-based polymer by a stretching method.

[0018] The stretched separation membrane is a high-porosity stretched separation membrane having pore diameters of 0.05 μm to 10 μm, and the stretched separation membrane can be in contact with the inside or outside of a porous tubular support.

[0019] The stretching separation membrane may include a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and a mixture thereof.

[0020] The porous tubular support may include a non-woven fabric made of polyethylene terephthalate (PET) yarn.

[0021] The nonwoven fabric may be made of low-melting-point polyethylene terephthalate (PET) and yarns composed of polyethylene terephthalate (PET) in a sheath-core form.

[0022] The porous tubular support may be manufactured by laminating a non-woven fabric in a tubular shape by hot-melt lamination 1 to 30 times in an atmosphere of 100° C. to 200° C.

[0023] The inner diameter of the porous tubular support can be greater than 3 mm, the thickness can be greater than 0.1 mm, and the bending strength can be 50 N / mm 2 above.

[0024] According to another embodiment of the present invention, a method for manufacturing a tubular filter membrane using a stretch separation membrane may include: winding the stretch membrane on a metal rod to manufacture the stretch separation membrane; and hot-melt laminating a non-woven fabric on the outside of the stretch separation membrane in an atmosphere of 100°C to 200°C to manufacture a porous tubular support body; the non-woven fabric is hot-melt laminated on the outside of the stretch separation membrane 1 to 30 times.

[0025] The stretching separation membrane may include a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and a mixture thereof.

[0026] The stretched membrane may be a porous polytetrafluoroethylene (PTFE) stretched membrane obtained by biaxial stretching and having an average pore size of 0.05 μm to 0.2 μm, a width of 400 mm to 600 mm, and a thickness of 40 μm to 60 μm.

[0027] The nonwoven fabric may be made of polyethylene terephthalate (PET) yarn.

[0028] The nonwoven fabric may be made of low-melting-point polyethylene terephthalate (PET) and yarns composed of polyethylene terephthalate (PET) in a sheath-core form.

[0029] Effects of the Invention

[0030] The present invention relates to a separation membrane for removing particulate matter in the flow of liquids and gases, particularly as a tubular filter membrane used primarily in concentration processes or processes for treating raw water containing a large amount of sludge. When physical or chemical cleaning is performed to prevent or resolve membrane contamination associated with the use of the separation membrane, a more powerful cleaning method that prevents damage to the separation membrane caused by cleaning can be introduced.

[0031] In addition, in order to easily introduce high-intensity physical or chemical cleaning methods into the tubular filter membrane, a method for manufacturing the tubular filter membrane is provided, which introduces a separation membrane manufactured by a stretching method using an olefin-based or fluorine-based polymer with excellent physical and chemical properties into the tubular filter membrane, thereby further enhancing the advantages of the tubular filter membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 1 and 2 are results showing changes in bending load and average pore size of a porous tubular support according to an embodiment of the present invention as a function of the number of laminations.

[0033] Figure 2 The graph shows the bending load and average pore diameter of the porous tubular support according to one embodiment of the present invention under the lamination temperature conditions.

[0034] Figure 3 This is a SEM photograph of a stretched separation membrane according to one embodiment of the present invention.

[0035] Figure 4 This is a SEM photograph of a stretched separation membrane according to one embodiment of the present invention.

[0036] Figure 5 This is a SEM photograph of a stretched separation membrane according to one embodiment of the present invention.

[0037] Figure 6 This is a SEM photograph of a stretched separation membrane according to one embodiment of the present invention.

[0038] Figure 7 This is a SEM photograph of a stretched separation membrane according to one embodiment of the present invention.

[0039] Figure 8 FIG. 1 is a diagram illustrating a tubular filter membrane module using a tubular filter membrane according to an embodiment of the present invention.

[0040] Figure 9 The figures show the experimental results of the water permeability and filtration performance of a tubular membrane module using a tubular membrane according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention relates to a tubular filter membrane using a stretching separation membrane, which comprises a porous tubular support and a stretching separation membrane. The stretching separation membrane is manufactured by a stretching method using an olefin-based polymer or a fluorine-based polymer.

[0042] Hereinafter, the embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention in the technical field to which the present invention belongs. However, the present invention can be implemented in various ways and is not limited to the embodiments described here.

[0043] The tubular filter membrane of the present invention can be used as a separation membrane configured in a liquid filtration tubular filter membrane module or a gas filtration tubular filter membrane module. In the following description, the environmental filter membrane applied to the liquid filtration tubular filter membrane module is used for illustration.

[0044] If the tubular filter membrane is used for a long time, particles are excessively adsorbed on the membrane surface to form a layer, which reduces the separation efficiency of the membrane. This layer is called an agglomeration layer.

[0045] The tubular filter membrane itself can effectively remove the agglomerated layer due to its fast internal flow rate. However, in order to improve the efficiency of the tubular filter membrane, in the process of removing the agglomerated layer, i.e., the cleaning process, the advantage of the large internal diameter of the tubular filter membrane is utilized, and physical cleaning tools such as sponge balls, air cleaning, and backwashing are used. However, they can only be used within a range that does not cause surface scratches or pore collapse.

[0046] That is, the separation membrane included in the existing tubular filter membrane is a polymer material applied to the NIPS method. When using physical cleaning tools, it may cause surface damage and peeling of the separation membrane. Therefore, the agglomerated layer can only be removed within a limited range where such phenomena do not occur.

[0047] For the reasons described above, applicable cleaning methods are limitedly determined by the separation layer material of the tubular membrane, which is one of the main reasons for the limitation of separation membrane performance.

[0048] Damage to the separation layer is closely related to the life and performance of the separation membrane. Therefore, in order to overcome these problems, separation membranes made of olefin-based or fluorine-based polymer materials have attracted much attention due to their chemical resistance and mechanical strength. However, methods other than NIPS are subject to technical limitations, and therefore tubular membranes made of olefin-based or fluorine-based materials are not yet available as tubular filtration membranes.

[0049] In order to apply olefin-based or fluorine-based polymer materials with excellent mechanical strength, it is preferred to use the TIPS method or stretching method instead of the NIPS method. However, the TIPS method or stretching method is difficult to apply to a hard support body, so it cannot be made into a tubular membrane.

[0050] The latest technology, the TIPS method, which involves adding a stretching process, cannot be applied to a rigid support, and therefore cannot achieve a tubular membrane form.

[0051] The biggest advantage of tubular membrane modules is that they can maintain high flow rates through wide-diameter flow path inlets and can introduce various physical cleaning tools within the wide diameter, making it easier to remove fouling substances (scale or cake) accumulated on the surface of the separation membrane during the filtration process.

[0052] In order to achieve better tubular membrane performance, it is necessary to apply olefin-based or fluorine-based materials with excellent mechanical strength to introduce a more efficient physical cleaning system to reduce membrane fouling.

[0053] The present invention offers the advantage of increasing the flow rate of the feed liquid, thereby achieving optimal fluid flow. Specifically, the present invention relates to a tubular membrane. By applying the properties of a stretched membrane to a tubular membrane module, primarily used in raw water treatment processes with high viscosity or high sludge content, such as concentration processes, the membrane surface is mechanically strengthened, thereby reducing surface scratches and pore collapse.

[0054] As described above, when removing the agglomerated layer accumulated on the surface of the separation membrane using a conventional tubular filter membrane, due to the characteristics of the separation membrane material, the separation membrane surface is damaged by surface scratches, resulting in pore collapse or peeling, etc., thus causing the separation membrane to be unable to perform its function.

[0055] The present invention relates to a tubular filter membrane using a stretched separation membrane, which includes a stretched separation membrane and a porous tubular support. The stretched separation membrane is not manufactured using a non-solvent induced phase separation method like the existing tubular filter membrane mentioned above, but is manufactured using an olefin-based polymer or a fluorine-based polymer through a stretching method.

[0056] By applying the stretched separation membrane of the olefin-based polymer or fluorine-based polymer material to manufacture a tubular filter membrane, the durability and mechanical strength of the stretched separation membrane in the tubular filter membrane are improved, thereby enabling a more effective implementation of the physical cleaning process for removing the agglomeration layer generated as the tubular filter membrane is used, thereby improving the efficiency of the separation membrane process and extending the life of the separation membrane.

[0057] The stretched separation membrane is a high-porosity stretched separation membrane having pore diameters of 0.05 μm to 10 μm, and the stretched separation membrane can be in contact with the inside or outside of a porous tubular support.

[0058] The diameters of the pores of the stretched separation membrane can be further divided according to the purpose of filtration to which the tubular filter membrane including the stretched separation membrane is applied, and the properties and state of the fluid to be filtered.

[0059] Specifically, the diameter of the pores may vary depending on whether the tubular filter membrane is used as a conventional microfiltration (MF), ultrafiltration (UF) or air conditioning filter and whether fluid and / or gas flows inside the inner diameter of the tubular filter membrane.

[0060] The stretch separation membrane comprises a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and mixtures thereof. Preferably, it can be polytetrafluoroethylene (PTFE), but is not limited to the example described above. It can be manufactured into a stretch separation membrane by a stretching method. Due to its excellent mechanical strength, when used as a tubular filter membrane, it can be used without restriction in situations where the separation membrane will not be damaged even in a physical cleaning process for removing agglomerate layers.

[0061] The porous tubular support may include a non-woven fabric made of polyethylene terephthalate (PET) yarn.

[0062] The porous tubular support is configured to connect the stretched separation membrane to the inside or outside, and needs to be able to enable the fluid or gas passing through the stretched separation membrane to move through the tubular support, and also to provide support so that deformation will not occur even if the flow rate of the fluid or gas passing through the stretched separation membrane is high.

[0063] That is, the tubular support must not only not hinder flow so that the fluid or gas can be filtered and moved together with the stretched separation membrane, but must also exhibit a certain level of strength so that it is not easily deformed by hydraulic or pneumatic pressure.

[0064] Therefore, in the present invention, the tubular support may include a nonwoven fabric made of polyethylene terephthalate (PET) yarn.

[0065] The nonwoven fabric may be made of low-melting-point polyethylene terephthalate (PET) and yarns composed of polyethylene terephthalate (PET) in a sheath-core form.

[0066] The low-melting-point polyethylene terephthalate (PET) has a melting point of 50° C. to 145° C., which is considerably lower than the melting point of general polyethylene terephthalate (PET) of 260° C.

[0067] More specifically, the core layer of the yarn constituting the non-woven fabric of the present invention is provided with polyethylene terephthalate (PET) having a relatively high melting point, and when heat is applied in the form of a skin layer in which the core layer is wrapped with polyethylene terephthalate (PET) having a low melting point, the polyethylene terephthalate having a low melting point melts at a relatively low temperature, thereby being able to improve the bonding effect.

[0068] The porous tubular support is made by hot-melt laminating the non-woven fabric in a tubular shape 1 to 30 times in an atmosphere of 100°C to 200°C. The porous tubular support can also be made by laminating the non-woven fabric to a metal rod 1 to 30 times as described later. At this time, when the non-woven fabric is hot-melt laminated in an atmosphere of 100°C to 200°C, the low-melting-point polyethylene terephthalate in the non-woven fabric is heated and melted and bonded. However, depending on the number of laminations, the bending load (N) and the average pore size of the porous tubular support may differ. That is, as the number of non-woven fabric laminations increases, the bending load increases linearly, and the average pore size does not hinder the flow of fluid or gas within the range of the number of laminations described later.

[0069] The fiber fineness used in the nonwoven fabric can be 0.5 De ​​to 10 De, or 1 De to 6 De, but is not limited to these examples. As the fineness of the fibers used to make the nonwoven fabric decreases, the average pore diameter of the nonwoven fabric and the tubular support tends to decrease, and the porosity increases. Therefore, considering that the fineness of the fibers used in the nonwoven fabric affects the number of laminations described above, it is preferable to use a nonwoven fabric made from fibers with a fineness within the above range.

[0070] In addition, the weight of non-woven fabric is 10g / m 2 Up to 300g / m 2 The range of production, but the gram weight can be changed according to the different uses, in the present invention, can use 50g / m 2 Up to 200g / m 2 Nonwoven fabrics with a grammage of 100%. Since the thickness and hardness of the nonwoven fabric itself tend to increase with the grammage of the nonwoven fabric, when obtaining a tubular support having the same thickness and strength, the number of laminations decreases as the grammage increases. Therefore, it is preferred to use a nonwoven fabric with a grammage within the above range.

[0071] To this end, in order to manufacture the porous tubular support, the nonwoven fabric can be laminated onto the metal rod 1 to 30 times, 3 to 30 times, 5 to 30 times, or 7 to 30 times. Depending on the number of laminations described above, suitable bending load and average pore size values ​​can be exhibited, thereby achieving a balance between the mechanical properties of the porous tubular support and the flow resistance of fluids or gases.

[0072] The inner diameter of the porous tubular support can be greater than 3 mm, the thickness can be greater than 0.1 mm, and the bending strength can be 50 N / mm 2The inner diameter of the porous tubular support can vary depending on the diameter of the metal rod when manufacturing the porous tubular support, but preferably, the porous tubular support has an inner diameter of 3 mm or greater. This is related to the use of the tubular filter membrane including the porous tubular support, as described later. A wide-diameter flow path inlet can be used, maintaining a high flow rate for the fluid or gas passing through the tubular filter membrane, thereby achieving excellent filtration results.

[0073] Specifically, by utilizing a tubular support having a large inner diameter as described above, the flow rate of fluid or gas passing through the tubular filter membrane of the present invention can be increased, thereby achieving good fluid flow. Specifically, the tubular filter membrane of the present invention is primarily used in raw water treatment processes such as concentration processes where the raw water has high viscosity or contains a large amount of sludge.

[0074] The thickness of the porous tubular support varies depending on the number of times the nonwoven fabric is laminated. As described later, lamination is achieved by wrapping the nonwoven fabric around a tubular stretched separation membrane and applying heat to the membrane. Therefore, varying the number of laminations means that the nonwoven fabric is bonded by heat and pressure, and the number of wrappings increases, resulting in a change in thickness.

[0075] As mentioned above, as the number of laminations increases, the mechanical strength increases accordingly. In order to use it as a tubular support, a thickness of 0.1 mm or more and a strength of 50 N / mm 2 Under the above bending strength, it can play the role of a tubular support.

[0076] Another embodiment of the present invention provides a method for manufacturing a tubular filter membrane using a stretch separation membrane, comprising: manufacturing a stretch separation membrane by winding the stretch membrane around a metal rod; and manufacturing a porous tubular support by heat-melt laminating a non-woven fabric on the outside of the stretch separation membrane in an atmosphere of 100°C to 200°C; the non-woven fabric can be heat-melt laminated on the outside of the stretch separation membrane 1 to 30 times.

[0077] In the manufacturing step of the stretched separation membrane, as described above, a stretched membrane comprising a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and a mixture thereof is wound on a metal rod to manufacture the membrane. Preferably, polytetrafluoroethylene (PTFE) can be used, but is not limited to the example described above.

[0078] The stretch release film can be manufactured into a tubular shape by winding the stretch film around a metal rod and ultrasonically welding the stretched film. The welding of the stretched film to manufacture the stretch release film is not limited to ultrasonic welding, and any method of welding the stretched film to manufacture a tubular stretch release film can be used.

[0079] The stretched membrane is a porous polytetrafluoroethylene (PTFE) stretched membrane having an average pore size of 0.05 μm to 0.2 μm, a width of 400 mm to 600 mm, and a thickness of 40 μm to 60 μm obtained by biaxial stretching. The stretched membrane is a porous polytetrafluoroethylene (PTFE) stretched membrane having an average pore size of 0.07 μm to 0.15 μm, a width of 450 mm to 550 mm, and a thickness of 45 μm to 55 μm obtained by biaxial stretching. The stretched membrane can use a porous polytetrafluoroethylene (PTFE) stretched membrane having an average pore size of 1 μm, a width of 500 mm, and a thickness of 50 μm obtained by biaxial stretching. When a stretched separation membrane is manufactured using a porous polytetrafluoroethylene stretched membrane having an average pore size, width, and thickness within the above ranges, not only excellent filtration effect is exhibited, but also excellent mechanical strength is exhibited, which can prevent damage to the separation membrane during the cleaning process.

[0080] After the stretched separation membrane is manufactured through the above process, a nonwoven fabric may be heat-fused laminated on the outside of the stretched separation membrane to manufacture a porous tubular support.

[0081] The non-woven fabric can be hot-melt laminated 1 to 30 times, and the non-woven fabric can be made of polyethylene terephthalate (PET) yarn, preferably, can be made of low-melting point polyethylene terephthalate (PET) and polyethylene terephthalate (PET) yarn in a sheath-core form.

[0082] The number of laminations and yarns of the nonwoven fabric are as described above.

[0083] A tubular membrane system according to another embodiment of the present invention includes the above-mentioned tubular filter membrane. The system may be a single tubular membrane including the tubular filter membrane, or may include multiple tubular filter membranes as a module.

[0084] Taking a single tubular membrane as an example, the tubular membrane system is a separation membrane module. Depending on the process design, the pores of the tubular membrane allow the filtered liquid to pass through, either from the outside to the inside of the tubular membrane or from the inside to the outside, and then discharge the filtered liquid. The system includes a collection pipe for collecting the treated liquid, a discharge section for discharging the treated liquid, and a backflushing section for supplying backflushing fluid. The pipes of the collection pipe and backflushing section can be configured and used in the same manner.

[0085] Example 1

[0086] Manufacturing of support for tubular filter membranes

[0087] In an atmosphere of 160°C, a non-woven fabric made of yarn composed of low-melting-point polyethylene terephthalate (PET) and ordinary PET in a sheath-core form was laminated 1, 3, 5, 7, 9, 20, and 30 times on a metal rod with an outer diameter of 20 mm and a length of 600 mm to obtain a hard body constituting a tubular filter membrane.

[0088] Example 2

[0089] Manufacturing of support for tubular filter membranes

[0090] Under atmospheres of 100°C, 130°C, 160°C, and 190°C, a non-woven fabric made of yarn composed of low-melting-point polyethylene terephthalate (PET) and ordinary PET in a sheath-core form was laminated 9 times on a metal rod with an outer diameter of 20 mm and a length of 600 mm to obtain a hard body constituting the tubular filter membrane.

[0091] Example 3

[0092] Manufacturing of tubular filter membrane support using unfired porous PTFE tube

[0093] An unsintered porous PTFE tube with an inner diameter of 20.5 mm and a thickness of 3 mm is placed on a metal rod with an outer diameter of 20 mm and a length of 600 mm. The two ends of the tube are tied and fixed with iron wire, and then sintered at about 360°C for 20 minutes to obtain a hard body that constitutes the tubular filter membrane.

[0094] Example 4

[0095] Production of tubular filter membranes using PTFE stretched membranes and nonwoven fabrics containing low-melting-point PET

[0096] A porous polytetrafluoroethylene (PTFE) stretched membrane with an average pore size of 0.1 μm, a width of 500 mm, and a thickness of 50 μm, obtained by winding two axes of extension around a metal rod with an outer diameter of 20 mm and a length of 600 mm, was wound once and fixed by ultrasonic welding. Then, as in Example 1 above, a non-woven fabric made of yarn composed of low-melting-point polyethylene terephthalate (PET) and ordinary PET in a sheath-core form was laminated 20 times at 160°C to form a hard body, thereby obtaining a tubular filter membrane.

[0097] Example 5

[0098] Manufacturing of tubular filter membranes using PTFE stretched membranes and unfired porous PTFE tubes

[0099] A porous polytetrafluoroethylene (PTFE) stretched membrane with an average pore size of 0.1 μm, a width of 500 mm, and a thickness of 50 μm, obtained by winding it around a metal rod with an outer diameter of 20 mm and a length of 600 mm, was wound once and fixed by ultrasonic welding. Then, as in Example 3 above, an unfired porous PTFE tube with an inner diameter of 20.5 mm and a thickness of 3 mm was installed, and the two ends of the tube were tied and fixed with iron wire. It was then sintered at about 360°C for 20 minutes to obtain a tubular filter membrane.

[0100] Experimental Example 1

[0101] The average pore size and flexural strength of the support body are measured with the number of non-woven fabric laminations

[0102] The three-point bending strength of the seven tubular membrane bodies obtained in Example 1 was measured using a universal testing machine (UTM), and the average pore size of the porous tubular supports was measured using a capillary flow pore analyzer capable of measuring the average pore size.

[0103] The three-point bending loads and average pore diameters of seven porous tubular supports are shown in Table 1 below. Figure 1 This is a graph comparing the bending load and average pore diameter of the porous tubular support obtained in Comparative Example 1 as a function of the number of laminations.

[0104] [Table 1]

[0105] Number of laminations of nonwoven fabrics Bending load (N) Average pore size (μm) 1 time 9 37.4 3 times 53 21.0 5 times 78 19.5 7 times 144 14.2 9 times 155 14.1 20 times 715 12.7 30 times 934 9.89

[0106] According to the experimental examples, the bending strength of the porous tubular support increases linearly with the number of laminations, and the average pore size decreases sharply until 7 times, but the reduction in the average pore size slows down significantly after 9 times or more. According to Table 1, it can be confirmed that when the number of laminations of the nonwoven fabric used in Example 1 exceeds 5 times, a support with sufficient bending strength and a suitable average pore size can be obtained. In addition, when the number of laminations exceeds 30 times, there is a trend in terms of economy and function that negative factors such as a decrease in unit price competitiveness due to excessive material consumption, a limited module compactness due to an increase in the thickness of the tubular support, and poor fluid flow due to a reduction in the average pore size are more obvious than positive factors.

[0107] Experimental Example 2

[0108] * Measurement results of average pore size and bending strength of porous tubular supports based on temperature conditions

[0109] The three-point bending strength of the four porous tubular supports obtained in Example 2 was measured using a universal testing machine (UTM), and the average pore size of each porous tubular support was measured using a capillary flow porometer capable of measuring the average pore size.

[0110] Table 2 shows the three-point bending load and average pore size of the four porous tubular supports. Figure 2 This is a graph comparing the bending load and average pore size of the porous tubular support body with the number of laminations.

[0111] [Table 2]

[0112] Lamination temperature conditions Bending load (N) Average pore size (μm) 100℃ 74 21.4 130℃ 146 15.4 160℃ 152 14.2 190℃ 158 13.4

[0113] Table 2 confirms that the bending strength and average pore diameter of the porous tubular support obtained at temperatures above 130°C differ significantly from those obtained at 100°C. The bending strength and average pore diameter of the tubular filter membrane obtained at temperatures above 130°C vary linearly with temperature, but the magnitude of the change is significantly smaller. Consequently, these experimental results confirm that the porous support for tubular filter membranes exhibits suitable bending strength and average pore diameter when manufactured at temperatures between 130°C and 190°C.

[0114] Experimental Example 3

[0115] Determination of flexural strength and average pore size of tubular filter membranes using unfired porous PTFE tubes

[0116] The three-point bending strength and average pore size of the tubular filter membrane body obtained in Example 3 were measured using a universal testing machine (UTM) and a capillary flow porometer, respectively, and compared with the three-point bending load and average pore size of the tubular filter membrane body obtained by laminating 5 and 9 times in Example 1.

[0117] Table 3 shows the three-point bending loads and average pore sizes of the three types of tubular filter membrane bodies.

[0118] [Table 3]

[0119] Bending load (N) Average pore size (μm) Example 1 (5 times) 78 19.5 Example 1 (9 times) 155 14.2 Example 3 (PTFE tube) 74 10.5

[0120] According to the experimental example, the three-point bending strength of the tubular filter membrane body obtained by Example 3 is similar to the bending strength of the body obtained by laminating 5 times in Example 1, and the average pore size of the tubular filter membrane body is smaller than the average pore size of the tubular filter membrane body obtained by Example 1.

[0121] Experimental Example 4

[0122] SEM image measurement results of stretched separation membrane

[0123] The surfaces of the stretched separation membranes of the two types of tubular filtration membranes produced in Examples 4 and 5 were measured using a scanning electron microscope (SEM).

[0124] Figure 3 and Figure 4 The surface of the stretched separation membrane is magnified 500 times and 3,000 times respectively. Figures 5 to 7 The photographs are magnified 10,000 times, respectively, of the PTFE stretched membrane and the stretched separation membranes of Examples 4 and 5.

[0125] like Figure 4 As shown in the figure, the facial features at 3,000 times magnification do not show any significant difference, but as Figures 5 to 7 As shown in the 10,000-fold magnification, the fineness of the microfibers forming the pore structure of the PTFE separation membrane is about 120 nm for the PTFE stretched membrane before processing, about 120 nm for the separation membrane obtained by Example 4, and about 250 nm for the separation membrane obtained by Example 5.

[0126] This confirmed that in Example 5, the microfibers of the stretched PTFE membrane changed during the sintering treatment at approximately 360° C. for 20 minutes.

[0127] Experimental Example 5

[0128] Filtration performance test

[0129] like Figure 8 As shown, the tubular filter membrane 1 obtained in Examples 4 and 5 was cut into 200 mm lengths and placed in the center of an acrylic cylinder 2 with an inner diameter of 40 mm and a length of 205 mm, equipped with a liquid collection port 3. Both ends of the acrylic cylinder and the tubular filter membrane were sealed with epoxy resin 4 to create a tubular filter membrane module. This module was fabricated to utilize a pressure-resistant, circulating cross-flow filtration method. Specifically, while the processed raw liquid formed an in-line flow from inlet 5 to outlet 6, treated water passed through the separation membrane toward the liquid collection port 3. The resulting tubular filter membrane module was used to test the water permeability and solid-liquid separation filtration performance of the tubular filter membrane.

[0130] The raw water used in the solid-liquid separation filtration performance test was prepared by dispersing clay in clean water to a turbidity of 200 NTU. Colloidal particles with particle sizes ranging from 0.1 μm to 20 μm were evenly distributed in the dispersion. The filtration condition was adjusted to an inlet pressure of 1.5 kg / cm 2 , outlet pressure 1.0kg / cm 2 The water permeability and filtration performance obtained through this test are as follows: Figure 9and as shown in Table 4.

[0131] [Table 4]

[0132] Clear water permeability (LMH) Treated water turbidity (NTU) Filtration performance (%) Example 4 5,000 4.4 97.8 Example 5 4,200 11.8 94.1

[0133] The experimental results in Table 4 confirm that the tubular filter membrane of Example 4 outperforms the tubular filter membrane of Experimental Example 5 in terms of water permeability and filtration performance. This is because, as confirmed in Experimental Example 3, when sintering PTFE to produce a tubular filter membrane, the microfibers of the stretched PTFE membrane change, resulting in differences in water permeability and filtration performance. While the preferred embodiments of the present invention have been described in detail above, the scope of protection of the present invention is not limited thereto. Various modifications and improvements implemented by those skilled in the art using the basic concepts of the present invention as defined in the following claims also fall within the scope of protection of the present invention.

[0134] Industrial applicability

[0135] The invention relates to a tubular filter membrane using a stretched separation membrane and a manufacturing method thereof.

Claims

1. A tubular filter membrane using a stretched separation membrane, characterized in that: It includes a porous tubular support and a stretchable separation membrane, The stretched separation membrane is manufactured using an olefin-based polymer or a fluorine-based polymer by a stretching method.

2. The tubular filter membrane using a stretchable separation membrane according to claim 1, characterized in that: The stretched separation membrane is a high-porosity stretched separation membrane having pore diameters of 0.05 μm to 10 μm. The stretched separation membrane is in contact with the inside or outside of the porous tubular support.

3. The tubular filter membrane using a stretchable separation membrane according to claim 1, characterized in that: The stretched separation membrane includes a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and a mixture thereof.

4. The tubular filter membrane using a stretchable separation membrane according to claim 1, characterized in that: The porous tubular support includes a non-woven fabric made of polyethylene terephthalate (PET) yarn.

5. The tubular filter membrane using a stretched separation membrane according to claim 4, characterized in that: The nonwoven fabric is made of low-melting-point polyethylene terephthalate (PET) and yarns composed of polyethylene terephthalate (PET) in a sheath-core form.

6. The tubular filter membrane using a stretched separation membrane according to claim 1, characterized in that: The porous tubular support is manufactured by laminating a non-woven fabric in a tubular shape by hot-melt lamination 1 to 30 times in an atmosphere of 100° C. to 200° C.

7. The tubular filter membrane using a stretchable separation membrane according to claim 1, characterized in that: The porous tubular support has an inner diameter of 3 mm or more, a thickness of 0.1 mm or more, and a bending strength of 50 N / mm 2 above.

8. A method for manufacturing a tubular filter membrane using a stretched separation membrane, characterized in that: include: The stretch film is wound on a metal rod to produce a stretch separation membrane; as well as manufacturing a porous tubular support by heat-melting and laminating a nonwoven fabric on the outside of the stretched separation membrane in an atmosphere of 100° C. to 200° C.; The nonwoven fabric is heat-melt laminated 1 to 30 times on the outside of the stretched release film.

9. The method for manufacturing a tubular filter membrane using a stretched separation membrane according to claim 8, wherein: The stretched separation membrane includes a polymer selected from the group consisting of polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and a mixture thereof.

10. The method for manufacturing a tubular filter membrane using a stretched separation membrane according to claim 8, wherein: The stretched film is a porous polytetrafluoroethylene (PTFE) stretched film obtained by biaxial stretching, with an average pore size of 0.05 μm to 0.2 μm, a width of 400 mm to 600 mm, and a thickness of 40 μm to 60 μm.

11. The method for manufacturing a tubular filter membrane using a stretched separation membrane according to claim 8, wherein: The nonwoven fabric is made of polyethylene terephthalate (PET) yarn.

12. The method for manufacturing a tubular filter membrane using a stretched separation membrane according to claim 8, wherein: The nonwoven fabric is made of low-melting-point polyethylene terephthalate (PET) and yarns composed of polyethylene terephthalate (PET) in a sheath-core form.

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