JP2007289932A - Microporous membrane manufacturing method and device used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microporous membrane manufacturing method which prevents mold from growing on a coated part of a wetting agent, and also to provide a device used for the same. <P>SOLUTION: The manufacturing device 10 of the microporous membrane 44 is provided with a brush member 62 for coating the wetting agent on the microporous membrane 44 and a drum 68 for drying the coated wetting agent. A filter unit 86 with a HEPA filter is arranged on an air feeding line 82 for feeding air to the drum 68. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing a microporous membrane, and more particularly to a method and apparatus for producing a polysulfone-based microporous membrane used in fields such as pharmaceutical industry, food industry, electronics industry, and nuclear industry.

  In fields such as the pharmaceutical industry and the food industry, microporous membranes are used to remove fine particles and bacteria of about 0.1 to 5 μm. This microporous membrane is generally produced using cellulose ester, aliphatic polyamide, polyfluorocarbon, polysulfone, polypropylene or the like as a raw material.

  Microporous membranes include symmetric membranes in which the pore diameter is uniform in the film thickness direction, and asymmetric membranes in which the pore diameter varies in the film thickness direction. Patent Document 1 describes a method for producing a microporous membrane having a minimum pore size layer inside the membrane. This microporous membrane has a smaller pore resistance on the surface of the membrane than the internal pore size, and thus has a low filtration resistance and a high efficiency of capturing fine particles and bacteria. Further, the microporous membrane of Patent Document 1 does not deteriorate the filtration performance even if the surface is lost, and can always maintain a high filtration performance.

Such a microporous membrane is used by being incorporated in a cartridge, for example (see Patent Document 2). Cartridges are typically integrity tested after incorporation of the microporous membrane. This test is for confirming that the microporous film has no defects such as pinholes and tears, and for example, a bubble point method, a diffusion flow rate method, and a pressure holding method are used. In either method, the test is performed with the microporous membrane wet. However, the microporous membrane in which the cartridge is incorporated has a problem that it is difficult to wet at the seal portion with the cartridge, that is, the end portion in the width direction of the microporous membrane. For this reason, in patent document 2, the wetting agent is apply | coated to the both ends of the width direction.
JP 63-139930 A JP 2002-224539 A

  By the way, since a hydrophilic polymer such as polyvinylpyrrolidone is used as the wetting agent, there is a problem that mold fungi are easily generated as it is. In particular, when microporous membranes are used in food manufacturing plants and pharmaceutical manufacturing plants, it is not possible to put preservatives in the wetting agent or the raw material of the membrane. There is.

  For this reason, conventionally, after the microporous membrane is incorporated in the cartridge, the entire cartridge has to be sterilized. However, there is a problem that it is difficult to completely sterilize the microporous membrane after it is assembled in the cartridge, and there is a need for a microporous membrane that does not easily generate mold at the stage of manufacturing the microporous membrane. There is a request.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a production method and apparatus for producing a microporous membrane capable of preventing the generation of mold fungi from the application part of the wetting agent.

  In order to achieve the above object, the invention according to claim 1 is a wetting agent application step for applying a wetting agent to the surface of the microporous membrane, and a wetting agent drying for drying the wetting agent applied in the wetting agent application step. In the method for producing a microporous membrane having a step, the wetting agent drying step blows air that has passed through a HEPA filter onto the surface of the microporous membrane.

  The inventor of the present invention is that the main cause of mold fungus generation in the application part of the wetting agent is the air for drying the wetting agent after application, and this air is passed through the HEPA filter to pass through the microporous membrane. It has been found that by spraying on the surface of the mold, mold fungi can be prevented from being generated from the application part of the wetting agent.

  The present invention has been made on the basis of such knowledge, and the wetting agent is dried by blowing the air that has passed through the HEPA filter onto the microporous film coated with the wetting agent. It is possible to prevent the occurrence of mold fungi from the coated part.

  The invention according to claim 2 is the invention according to claim 1, wherein the microporous membrane is for the food industry or the pharmaceutical industry. Microporous membranes used in the food and pharmaceutical industries are prone to mold fungi because preservatives cannot be used. However, when the present invention is applied to the production of microporous membranes for such uses, Occurrence can be prevented and it is effective.

  In order to achieve the above object, the invention according to claim 3 is a wetting agent application device for applying a wetting agent to the surface of the microporous membrane, and a wetting agent for drying the wetting agent applied by the wetting agent application device. In the apparatus for producing a microporous membrane having a drying device, the wetting agent drying device has a plurality of injection ports on an outer surface thereof, and the microporous membrane is applied to the outer surface by injecting air from the injection ports. A non-contact conveying roller that floats and supports from the above, and an air supply means that is connected to the non-contact conveying roller via an air supply line and supplies the air ejected from the ejection port to the non-contact conveying roller; And an HEPA filter disposed on the air supply line.

  According to the present invention, since the wetting agent is dried by blowing the air that has passed through the HEPA filter to the microporous membrane to which the wetting agent is applied, mold fungi are generated from the application portion of the wetting agent. Can be prevented.

  Preferred embodiments of a method and apparatus for producing a microporous membrane according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 schematically shows the configuration of a microporous membrane manufacturing apparatus according to the present embodiment. A dissolution tank 12 shown in the figure is a tank for preparing a dope for forming a microporous film. Inside the dissolution tank 12, a film forming polymer is dissolved in a solvent to prepare a dope. A jacket 14 is attached to the dissolution tank 12, and the dope in the dissolution tank 12 is maintained at a constant temperature by circulating a heat medium through the jacket 14.

  The dope in the dissolution tank 12 is sent to the die 18 of the coating apparatus by the liquid feed pump 16 in a state where the temperature and the dissolution state are stable. The dope is continuously discharged from the tip of the die 18 toward the belt-like support 20.

  The belt-like support 20 is made of, for example, a polyester film, wound in a roll shape, and attached to the rewinding roller 22. The belt-like support 20 is unwound from the rewinding roller 22 and wound around the drum 24 to be supported. The belt-like support 20 is guided by guide rollers 28 and 28 in a coagulation tank 26 to be described later, and then wound in a roll shape by a take-up roller 34 through a guide roller 30 and a peeling roller 32.

  The dope discharged from the die 18 is cast and applied onto a belt-like support 20 that is wound around and supported by a drum 24. As a result, a liquid film of dope (a film that will later become the microporous film 44) is formed on the surface of the belt-like support 20.

  The belt-like support 20 on which the dope liquid film is formed first travels vertically in the humidity control zone 36 downward. The humidity control zone 36 is formed so that the casing 38 covers the liquid film side surface of the belt-like support 20 from the drum 24 to the coagulation tank 26. Further, inside the humidity control zone 36, the conditioned air is blown in the traveling direction of the belt-shaped support body 20 (that is, downward). Specifically, a humidity control air supply port 36 </ b> A is provided above the humidity control zone 36, and a humidity control air exhaust port 36 </ b> B is provided below the humidity control zone 36. A circulation duct 40 is connected to the air supply port 36A and the exhaust port 36B, and an air conditioner 42 is provided in the circulation duct 40. The air conditioner 42 sucks air from the exhaust port 36B, adjusts the temperature and humidity of the air, and then sends the air to the air supply port 36A. Thereby, humidity control air adjusted to a predetermined greenhouse temperature is sent to the humidity control zone 36, and the inside of the humidity control zone 36 is maintained at a predetermined temperature and humidity.

  In addition, it is preferable to adjust humidity control air within the range of the relative humidity of 10-80% and the wind speed of 0.2-4 m / sec at the temperature of 15-60 degreeC. Moreover, in the humidity control zone 36, it is preferable that the liquid film on the surface of the strip | belt-shaped support body 20 is exposed to humidity control air for 2 to 17 seconds.

  By passing through the humidity control zone 36, the liquid film on the belt-like support 20 undergoes coacervation from the surface toward the inside, and forms a fine coacervation phase from the surface of the liquid film to the inside. That is, in the humidity control zone 36, the non-solvent vapor (for example, moisture) is absorbed from the air while the solvent is evaporated, and a phase separation state is created only in the vicinity of the surface. When formed, micropores can be formed inside the membrane, and relatively large pores can be formed on the surface of the membrane.

  The belt-like support 20 that has passed through the humidity control zone 36 is immersed in the coagulating liquid in the coagulation tank 26 by traveling while being guided by the guide rollers 28 and 28 in the coagulation tank 26. As the coagulation liquid, a liquid (for example, water) that is a non-solvent for the dope polymer and is compatible with the polymer solvent is preferable. By immersing in this coagulating liquid, the liquid film on the surface of the belt-like support 20 is dissolved in the solvent and replaced with the coagulating liquid, and the solvent replacement is performed. Then, the coacervation phase formed in the humidity control zone 36 is fixed as micropores, and at the same time, pores other than micropores are formed by phase separation of the liquid film, and the microporous membrane 44 is formed.

  The microporous membrane 44 is led out from the coagulation tank 26 in close contact with the belt-like support 20. Then, the strip-shaped support 20 is stripped from the microporous film 44 by the peeling roller 32, and the strip-shaped support 20 after stripping is wound around the winding roller 34.

  On the other hand, the peeled microporous film 44 travels by driving the feed roller 46 and is introduced into the washing tank 48. In the washing tank 48, turn bars 50, 50... Are provided in the washing liquid, and the microporous membrane 44 is guided by the turn bars 50, 50. Then, when the microporous film 44 travels in the washing liquid in the washing tank 48, the solvent or the like attached to the microporous film 44 is washed away.

  The microporous membrane 44 after washing with water is sent to the drying chamber 52. The drying chamber 52 is provided with drying drums 54, 54 ..., and the microporous membrane 44 is dried by being wound around the drying drums 54, 54 ....

  The microporous film 44 after drying is sent to a wetting agent coating chamber 56. A wetting agent preparation tank 58 is provided in the coating chamber 56, and the wetting agent is prepared by the preparation tank 58. As the wetting agent, a material that is safe even when mixed in foods and pharmaceuticals and can be easily washed away with water is preferable. For example, hydrophilic polymers such as polyvinylpyrrolidone and derivatives thereof, methylcellulose, hydroxymethylcellulose and derivatives thereof, ethylcellulose, hydroxyethylcellulose and derivatives thereof are preferable because they are highly safe, have a high wetting effect, and can be easily washed off with water. . For the same reason, surfactants such as alkyl sulfonates having 6 to 24 carbon atoms and higher fatty acid esters of sucrose are also preferred. As this alkyl sulfonate, sodium salt, potassium salt and lithium salt are preferable, and the fatty acid of the sucrose fatty acid ester preferably has 6 to 24 carbon atoms.

  The wetting agent in the preparation tank 58 is fed through the tube 60 by a pump (not shown). A brush member 62 made of felt or the like is provided at the tip of the tube 60, and this brush member 62 comes into contact with both ends in the width direction of the microporous film 44 guided by the guide rollers 64, 64. It has become. Thereby, the wetting agent is applied to both end portions in the width direction of the microporous film 44.

As a coating amount of the wetting agent, for example, in the case of polyvinylpyrrolidone and derivatives thereof, 1 to 6 g / m ² is preferable, and ² to 4 g / m ² is more preferable. In the case of methyl cellulose, hydroxymethyl cellulose and derivatives thereof, 0.1 to 1 g / m ² is preferable, and 0.2 to 0.6 g / m ² is more preferable. If the surfactant is preferably ^{0.05~0.1g / m 2, 0.1~0.3g / m} 2 is more preferable. The application position need only be a few millimeters from each end of the membrane.

  The method of applying the wetting agent is not limited to the above method. For example, the wetting agent may be applied by bringing a wetting agent soaked in a sponge or cloth into contact with the microporous film 44, a bead coater, You may apply | coat by known application methods, such as a gravure coater and a bar coater.

  The microporous film 44 to which the wetting agent is applied is sent to a wetting agent drying chamber 66. The drying chamber 66 is provided with non-contact conveying drums 68 and 68, and a plurality of holes for blowing out air are provided on the outer peripheral surfaces of the drums 68 and 68. The microporous film 44 is wound around the drums 68 and 68 so as to be supported and conveyed without contact, and the wetting agent on the surface of the microporous film 44 is dried.

  The microporous membrane 44 dried from the wetting agent travels inside the adjustment chamber 70 adjusted to a predetermined temperature and humidity while being guided by the guide rollers 72, 72, and then sent to the winding chamber 74 to form a roll. It is wound up.

  Next, the drying process of the wetting agent, which is a characteristic part of the present invention, will be described. FIG. 2 schematically shows the wetting agent drying step. In the wetting agent drying chamber 66 shown in FIG. 2, drums (corresponding to non-contact conveying rollers) 68 and 68 and guide rollers 69 and 69 are provided. Inside the wetting agent drying chamber 66, the microporous film 44 is guided without contact on the surface side (wetting agent application surface side) by the drums 68, 68 and directly on the back side by the guide rollers 69, 69. Guided and transported. Note that the number and arrangement of the drums 68 and the guide rollers 69 are not limited to those shown in FIG. 2. For example, one or three or more drums 68 may be provided.

  The drum 68 is formed in a cylindrical shape as shown in FIG. One side surface (not shown) of the drum 68 is sealed, and the other side surface is provided with an air supply port 68A, and air is supplied into the drum 68 from the air supply port 68A. In addition, a large number of through holes 68B, 68B... Are formed on the outer peripheral surface of the drum 68 so that the air supplied to the inside of the drum 68 can be ejected from the through holes 68B, 68B. It has become. The through holes 68B, 68B,... Are arranged in a staggered manner at equal intervals in the outer surface of the drum 68 where the microporous film 44 wraps (that is, in the range where the microporous film 44 faces). ing. As a result, the microporous film 44 wrapped around the drum 68 can be stably levitated and supported by the air jetted from the through hole 68B. A restriction plate (not shown) that divides the internal space in the width direction is provided inside the drum 68 so as to be movable in the width direction, and this restriction plate may be aligned with the end position of the microporous film 44 in the width direction. . In this case, by supplying air to the inside of the regulation plate, air is jetted only from the through holes 68B, 68B... Facing the microporous film 44, so that the microporous film 44 is supported more stably. can do.

  As shown in FIG. 2, air supply lines 82 and 82 are connected to the air supply ports 68A and 68A of the drums 68 and 68, respectively. The air supply lines 82 and 82 are connected to the air outlet of the fan 84 via the heater unit 88 and the filter unit 86. The fan 84 communicates with the drying chamber 66 through the intake line 83 at the intake port. Therefore, by driving the fan 84, the air in the drying chamber 66 is sucked into the intake line 83 and is supplied to the air supply ports 68 </ b> A and 68 </ b> A of the drums 68 and 68 through the air supply line 82.

  The heater unit 88 disposed in the air supply line 82 is a device that heats the air in the air supply line 82 to a desired temperature. The heater unit 88 adjusts the air flowing through the air supply line 82 to a temperature suitable for drying the wetting agent.

  On the other hand, the filter unit 86 is provided with a HEPA filter (High Efficiency Particulate Air) therein. The HEPA filter has a dust collecting power capable of collecting and removing 99.97% of fine particles of 0.3 μm. By passing air through the HEPA filter, fungi are collected and removed from the air supply line 82. can do. Accordingly, the sterilized air can be supplied to the drum 68.

  According to the wetting agent drying step configured as described above, the sterilized air is supplied to the drum 68, and this air is sprayed from the through-hole 68B of the drum 68 and blown onto the wetting agent application surface. It is possible to prevent mold fungus from adhering to the dry wetting agent. Therefore, mold fungi can be prevented from being generated from the application part of the wetting agent.

  In addition, when antibacterial components such as hinokitiol are contained in the above HEPA filter, the sterilization performance can be further improved.

  In the above-described embodiment, not only the air supplied to the drum 68 but also the air supplied to the inside of the wetting agent drying chamber 66 may be sterilized by the HEPA filter. Thereby, since the wetting agent drying process is performed in the sterilized atmosphere, it is possible to more reliably prevent mold bacteria from adhering to the undried wetting agent. Therefore, generation | occurrence | production of mold | fungi can be prevented more reliably from the application part of a wetting agent.

  In the above-described embodiment, all steps after the application of the wetting agent may be performed in a sterilizing atmosphere. That is, the air supplied to the wetting agent application chamber 56, the wetting agent drying chamber 66, the adjustment chamber 70, and the winding chamber 74 may be sterilized with HEPA. Thereby, it can prevent more reliably that mold | fungi are generated from the application part of a wetting agent.

  In addition to the wetting agent drying process shown in the above-described embodiment, when the wetting agent adjustment process and the wetting agent application process shown in FIGS. 4 to 7 are combined, mold fungi are generated from the application part of the wetting agent. Furthermore, it can prevent reliably.

  FIG. 4 schematically shows an example of the wetting agent preparation step and the wetting agent application step. Hereinafter, an example in which polyvinyl pyrrolidone and ion-exchanged water are mixed as a wetting agent will be shown.

  As shown in FIG. 4, the preparation tank 58 is connected to a tank 76 of ion exchange water via a pipe 75, and the ion exchange water in the tank 76 is fed by a liquid feed means (not shown). 75 and supplied to the preparation tank 58. The preparation tank 58 is connected to a polyvinyl pyrrolidone tank 78 via a pipe 77, and the polyvinyl pyrrolidone in the tank 78 is fed by liquid feeding means (not shown), and the preparation tank 58 is connected via the pipe 77. To be supplied.

  A filtration device 80 is provided in the pipe 75 between the ion-exchange water tank 76 and the preparation tank 58. A filter (not shown) having a pore diameter of 0.1 to 0.7 μm is provided inside the filtration device 80, and the ion exchange water flowing through the pipe 75 is filtered by passing through the filter. Thereby, mold fungi having a size of 0.8 μm or more are reliably removed from the inside of the ion exchange water and supplied to the preparation tank 58.

  The filtered ion exchange water and the polyvinyl pyrrolidone in the tank 78 are weighed and sent to the preparation tank 58. Thereby, a polyvinylpyrrolidone solution having a predetermined concentration (for example, 5%) is prepared as a wetting agent. The prepared wetting agent is fed to the brush member 62 through the tube 60 and applied to both ends of the microporous film 44 in the width direction by the brush member 62.

  When ion-exchanged water before preparation is filtered in this way, mold bacteria present in the ion-exchanged water are collected and removed by the filtration process, so mold fungi are not generated from the prepared wetting agent. Therefore, by applying the adjusted wetting agent to the microporous film 44 and further drying the wetting agent in the above-described wetting agent drying step, mold fungi are more reliably generated from the wetting agent application portion. Can be prevented.

  FIG. 5 schematically shows another embodiment of the wetting agent preparation step and the coating step. A filtration device 80 shown in FIG. A filter having a pore diameter of 0.1 to 0.7 μm is provided inside the filtration device 80, and the prepared wetting agent is filtered by this filter. Therefore, mold fungi contained in the prepared wetting agent can be collected and removed by the filtration device 80, and a wetting agent free from mold fungus can be applied to the microporous film 44. Therefore, by combining with the above-described wetting agent drying step, it is possible to more reliably prevent mold fungi from being generated from the wetted agent application portion of the microporous film 44.

  In the steps shown in FIGS. 4 and 5, the number of filtration processes is one, but the number of filtration processes is not limited to this and may be performed a plurality of times. Moreover, you may make it perform both the filtration process of the ion exchange water shown in FIG. 4, and the filtration process of the wetting agent shown in FIG.

  FIG. 6 schematically shows another embodiment of the wetting agent preparation step and the application step. The tank 76 shown in the figure is equipped with a jacket 79, and a heat medium (steam, hot water, etc.) heated to a desired temperature is supplied into the jacket 79 as needed. Yes. Thereby, the ion exchange water in the tank 76 can be heated and sterilized. Therefore, since the wetting agent is prepared using ion-exchanged water without mold fungus, the wetting agent without mold fungus can be applied to the microporous membrane 44, and in combination with the wetting agent drying step described above, It can prevent more reliably that mold | fungi are generated from the application | coating part of the wetting agent of the microporous film | membrane 44. FIG.

  In the embodiment of FIG. 6, the ion exchange water in the tank 76 is heated and sterilized. However, the ion exchange water before the preparation may be heated and sterilized. The ion exchange water in the pipe 75 may be heated and sterilized by mounting. In addition to the jacket 79, for example, a heater or a heat exchanger may be used as the heat sterilization means for the ion exchange water.

  FIG. 7 schematically shows another embodiment of the wetting agent preparation step and the application step. The tank 58 shown in the figure is provided with a jacket 59, and a heat medium (steam, hot water, etc.) heated to a desired temperature is supplied into the jacket 59 as required. Yes. Thereby, the prepared wetting agent in the tank 58 can be heated and sterilized. Therefore, the wetting agent without mold fungus can be applied to the microporous film 44, and by combining with the above-described wetting agent drying process without adhesion of mold fungus, the wetting agent application part of the microporous film 44 can be applied. Generation | occurrence | production of mold | fungi microbe can be prevented more reliably.

  In the embodiment of FIG. 7, the wetting agent in the preparation tank 58 is heated and sterilized. However, the prepared wetting agent may be heated and sterilized. By mounting, the wetting agent in the tube 60 may be heated and sterilized. In addition to the jacket 59, for example, a heater or a heat exchanger may be used as the heat sterilization means for the wetting agent.

  Moreover, you may provide both the heat-sterilization means of ion-exchange water, and the heat-sterilization means of a wetting agent. Further, the ion exchange water heat sterilization means and the wetting agent heat sterilization means may be used in combination with the ion exchange water filtration device and the wetting agent filtration device described above. In any combination, since the wetting agent without mold fungus can be applied to the microporous film 44, the microporous film 44 is combined with the above-described wetting agent drying process without adhesion of mold fungus. It can prevent more reliably that mold | fungi generate | occur | produce from the application part of this wetting agent.

  In the above-described embodiment, the portion where the wetting agent contacts and the portion where the raw material contacts (that is, the preparation tank 58, the tanks 76, 78, the piping 75, 77, the filtering device 80, the tube 60, and the brush member 62). It is preferable to sterilize before use. Although the sterilization method is not particularly limited, for example, it is preferable to sterilize with an ethanol solution (ethanol 70% or more is preferable). Moreover, you may make it heat-sterilize with boiling water.

  The dope for forming a microporous film used in the present invention will be described below. The dope contains a film-forming polymer, and the polymer is dissolved in a good solvent, a mixed solvent of a good solvent and a non-solvent, or a mixture of a plurality of solvents having different solubility in the polymer. Produced.

  The type of polymer is not particularly limited and is selected according to the use of the microporous membrane. For example, as the polymer, cellulose acetate, nitrocellulose, polysulfone, sulfonated polysulfone, polyethersulfone, polyacrylonitrile, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polycarbonate, organosiloxane -Polycarbonate copolymers, polyester carbonates, organopolysiloxanes, polyphenylene oxides, polyamides, polyimides, polyamideimides, polybenzimidazoles and the like.

  Moreover, although a solvent changes with kinds etc. of a polymer, what is rapidly substituted by coagulating liquid is preferable. In many cases, water and / or an organic solvent compatible with water are used as the coagulation liquid, and therefore it is preferable to use a polar solvent compatible with the coagulation liquid. For example, when the film-forming polymer is polysulfone, dioxane, tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, or a mixed solvent thereof is used. Further, when the polymer is polyacrylonitrile, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like are preferable. When the polymer is polyamide, dimethylformamide and dimethylacetamide are preferable, When the polymer is cellulose acetate, acetone, dioxane, tetrahydrofuran, N-methyl-2-pyrrolidone and the like are preferable.

  Examples of the non-solvent when mixing the non-solvent include water, cellosolves, methanol, ethanol, propanol, acetone, tetrahydrofuran, polyethylene glycol, glycerin and the like. The ratio of the non-solvent to the good solvent may be any range as long as the mixed solution can maintain a uniform state, but is preferably 5 to 50% by weight.

  In order to control the porous structure, it is preferable to add an inorganic electrolyte, an organic electrolyte, a polymer, or an electrolyte polymer called a swelling agent to the polymer solution. Examples of swelling agents include metal salts of inorganic acids such as sodium chloride, lithium chloride, sodium nitrate, potassium nitrate, sodium sulfate, and zinc chloride, metal salts of organic acids such as sodium acetate and sodium formate, and polymers such as polyethylene glycol and polyvinyl pyrrolidone. Polymeric electrolytes such as sodium polystyrene sulfonate and polyvinylbenzyltrimethylammonium chloride, ionic surfactants such as sodium dioctyl sulfone succinate and sodium alkylmethyl taurate are used. These swelling agents may be added to the solution alone, but exhibit a remarkable effect when added as an aqueous solution. The amount of the swelling agent added is not particularly limited as long as the addition does not impair the uniformity of the solution, but is usually 0.5% by volume to 10% by volume with respect to the solvent. Furthermore, there is no restriction | limiting in particular also about the density | concentration of a swelling agent, The one where a big concentration has a big effect is acquired, and 1 to 60 weight% is preferable normally.

  The concentration of the polymer solution is preferably 5 to 35% by weight, and more preferably 10 to 30% by weight. This is because when the amount exceeds 35% by weight, the water permeability of the obtained microporous membrane is so small that it has no practical meaning. On the other hand, when the amount is less than 5% by weight, the microporous membrane has sufficient separation ability. This is because cannot be obtained.

  Example 1: Production of microfiltration membrane 15 parts of polysulfone (P-3500, manufactured by Amoco), 70 parts of N-methyl-2-pyrrolidone, 15 parts of polyvinylpyrrolidone, 2 parts of lithium chloride and 1.3 parts of water are uniformly dissolved. Thus, a film forming stock solution was prepared. Using this, casting was performed so that the product thickness was 180 μm, and air at a temperature of 25 ° C., a relative humidity of 50% and a wind speed of 1.0 m / second was applied to the surface of the liquid film cast for 8 seconds, and immediately 25 ° C. Was immersed in a coagulation bath filled with water to obtain a microporous membrane. And the wetting agent was apply | coated to each 10 mm width of the width direction both ends of a microporous film | membrane. As the wetting agent, ion-exchange water for preparing the wetting agent was heated at 60 ° C. for 5 minutes, and then polyvinylpyrrolidone was added to prepare a 3.5% vinylpyrrolidone solution. In addition, wetting agent is applied by inserting a long and thin felt at the tip of the vinyl tube, leaving the tip of the felt about 1 cm from the tube to lightly contact the microporous membrane, and 2.5 ml per minute on the felt with a non-pulsating pump. The wetting agent was sent at a flow rate of. After application of the wetting agent, the microporous film was transported by a non-contact transport roller and dried by warm air that passed through a HEPA filter. And the both ends of the film | membrane were cut | judged in the approximate center position of the application | coating position, and it wound up with the film | membrane width of 240 mm.

  Example 2: After applying the wetting agent, the coating film was conveyed with a SUS flat roller and dried under warm air that passed through a HEPA filter.

  Comparative example 1: It implemented on the same conditions as Example 1 except not using a HEPA filter.

  Comparative example 2: It carried out on the same conditions as Example 1 except not using a HEPA filter and conveying the coating film with the SUS flat roller after application | coating.

  The microporous film formed under the above conditions was evaluated. The evaluation was as follows: 1) Number of defects of film: 10 fields of 10 cm × 10 cm area was observed with a 20-fold magnifier, and the number of defects was counted. 2) Corrosion of the coated part: After the film coated with the film edge wetting agent was left at 25 ° C. and 70% RH for 14 days, the number of molds was counted in the range of 10 mm wide and 50 cm long. The results are shown in Table 1.

  As can be seen from Table 1, in Comparative Examples 1 and 2 in which the hot air for drying was not passed through the HEPA filter, defects occurred in the microporous membrane, and fungi were present at the end of the microporous membrane. Occurred. Particularly, in Comparative Example 2 in which conveyance was performed by a flat roller without performing non-contact conveyance, both the number of defects of the microporous membrane and the number of molds were increased. On the other hand, Examples 1 and 2 in which the warm air for drying was passed through the HEPA filter could prevent the defects of the microporous membrane and fungi.

Configuration diagram showing a microporous membrane production apparatus according to the present invention Configuration diagram showing wetting agent drying process The perspective view which shows the drum of FIG. Configuration diagram showing examples of wetting agent preparation process and coating process Configuration diagram showing another example of wetting agent preparation process and coating process Configuration diagram showing another example of wetting agent preparation process and coating process Configuration diagram showing another example of wetting agent preparation process and coating process

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Microporous membrane manufacturing apparatus, 12 ... Dissolution tank, 18 ... Die, 20 ... Strip support, 22 ... Drum, 26 ... Coagulation tank, 36 ... Humidity control zone, 44 ... Microporous membrane, 48 ... Washing with water Tank, 50 ... Turn bar, 52 ... Drying chamber, 56 ... Wetting agent application chamber, 58 ... Preparation tank, 66 ... Wetting agent drying chamber, 68 ... Drum, 80 ... Filtration device, 86 ... Filter unit

Claims (3)

In a method for producing a microporous membrane, comprising a wetting agent application step of applying a wetting agent to the surface of the microporous membrane, and a wetting agent drying step of drying the wetting agent applied in the wetting agent application step.
In the method of manufacturing a microporous membrane, the wetting agent drying step blows air that has passed through a HEPA filter onto the surface of the microporous membrane.   The method for producing a microporous membrane according to claim 1, wherein the microporous membrane is for the food industry or the pharmaceutical industry. In a microporous membrane manufacturing apparatus, comprising: a wetting agent application device that applies a wetting agent to the surface of the microporous membrane; and a wetting agent drying device that dries the wetting agent applied by the wetting agent application device.
The wetting agent drying device
A non-contact conveying roller that has a plurality of ejection ports on its outer surface and supports the microporous film by floating from the outer surface by ejecting air from the ejection ports;
An air supply means connected to the non-contact conveying roller via an air supply line, and for supplying air injected from the injection port to the non-contact conveying roller;
A HEPA filter disposed on the air supply line;
An apparatus for producing a microporous membrane, comprising:

Images