JP2002066281A - Precise filter cartridge and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precise filter cartridge having resistance against an acid, alkali, an oxidizing agent and a high temperature alcohol, having a hydrophilic filter film, generating no air lock and capable of being easily subjected to incineration treatment after use, and a method for manufacturing the same. SOLUTION: In the precise filter cartridge, all of the hydrophilic microporous filter film, film support, core, outer peripheral cover and end plate constituting the filter cartridge are formed from a polysulfone based polymer. The filter cartridge is washed with hot ultrapure water heated to 50-100 deg.C for 15 min or more after assembling and subsequently dried in a clean oven. When ultrapure water with a specific resistance value of 18 MΩ is passed through the filter cartridge in a flow rate of 8 l/min per one 10 inch cartridge, TOC in an ultrapure filtrate reaches 5 ppb or less within 10 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cartridge filter using a microporous filtration membrane. The present invention particularly relates to a cartridge filter using a microporous microfiltration membrane having excellent chemical resistance and hydrophilicity, and a method for producing the same.

[0002]

2. Description of the Related Art In a wafer cleaning process for manufacturing a semiconductor integrated circuit, a cleaning solution composed of various acids, alkalis and oxidizing agents is used. Conventionally, a microporous microfiltration membrane made of polytetrafluoroethylene (PTFE) has been used for filtering such a chemical solution, and a filtration filter using a fluorine-based polymer has been used for other filter components. ing. However, the PTFE filtration membrane is extremely hydrophobic, so it is necessary to pre-wet with an alcohol such as isopropanol before starting the filtration of the chemical solution, then rinse off the alcohol with ultrapure water, and extrude the ultrapure water with the cleaning chemical to replace it. And generated a lot of unnecessary waste liquid. Even if filtration is started by wetting the membrane in this way, there is a problem that airlock is easily caused by entry of a small amount of air bubbles and often filtration cannot be performed. When disposing of the used fluorine-based polymer filter,
There were also problems such as generation of toxic gas by incineration.

[0003]

Accordingly, the present invention is directed to a chemical solution containing various acids, alkalis, alcohols, oxidizing agents and the like frequently used in a semiconductor manufacturing process, a pharmaceutical manufacturing process and the like, and in particular, hydrochloric acid in a semiconductor manufacturing process. Resistant to mixed liquids of hydrogen and hydrogen peroxide, dilute hydrofluoric acid, mixed liquids of hydrofluoric acid and ammonium fluoride, mixed liquids of hydrofluoric acid and hydrogen peroxide, or mixed liquids of ammonia and hydrogen peroxide It is an object of the present invention to provide a filter cartridge that can easily incinerate a used filter. To this end, the present inventor has previously invented a hydrophilic microfiltration filter cartridge in which all constituent materials are made of a polysulfone-based polymer, a so-called all-polysulfone filter.
No. 6798. However, hydrophilic microfiltration membranes using polysulfone-based polymers use many organic materials in the membrane formation process, and some of them are likely to remain in the membrane or to be contaminated with organic impurities. Even a small amount of organic contaminants remaining on or adhering to the filtration membrane is dangerous because the semiconductor performance that can be eluted into the filtrate can be significantly impaired. A second object of the present invention is to provide an all-polysulfone filter having little elution of organic substances, that is, TOC.

[0004]

The objects of the present invention have been attained by the following inventions. (1) A microfiltration filter cartridge in which all of the hydrophilic microporous filtration membrane, membrane support, core, outer peripheral cover, and end plate that make up the filter cartridge are made of a polysulfone-based polymer. A method for producing a microfiltration filter cartridge, characterized in that it is washed with hot ultrapure water at a temperature of C to 100 ° C for at least 15 minutes and then dried in a clean oven. (2) A microfiltration filter cartridge in which all of the hydrophilic microporous filtration membrane, the membrane support, the core, the outer peripheral cover, and the end plate that constitute the filter cartridge are made of a polysulfone-based polymer. The filter is washed with hot ultrapure water of C or more and 100 ° C or less for 15 minutes or more, dried in a clean oven, and then passed through the filter cartridge at a flow rate of 8 liters per minute per 10-inch cartridge. ΔTO in filtrate ultrapure water when ultrapure water of 18 megohms is passed through
A microfiltration filter cartridge wherein C reaches 5 ppb or less within 10 minutes.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The microfiltration filter cartridge referred to in the present invention is sometimes called a membrane filter cartridge or a microfilter cartridge. The general shape is known as a pleated cartridge having a structure in which a filtration membrane and a membrane support for protecting the filtration membrane are folded in a pleated shape, and a flat plate stacked cartridge formed by stacking a plurality of flat plate filtration units. I have. . Examples of the structure of the pleated cartridge are disclosed in, for example, JP-A-4-235722 and JP-A-10-66842.
Regarding the structure of the flat sheet laminated cartridge,
63-80815, JP-A-56-129016 and JP-A-58-98111. Hereinafter, the structure and manufacturing method of the pleated cartridge will be described in detail. FIG. 1 is a developed view showing the entire structure of a general pleated microfiltration membrane filter. The microfiltration membrane 3 is folded while being sandwiched by two membrane supports 2 and 4 and wound around a core 5 having many liquid collecting ports. An outer peripheral cover 1 is provided on the outside to protect the microfiltration membrane. End plates 6a at both ends of the cylinder,
6b seals the microfiltration membrane. The end plate is in contact with a seal portion of a filter housing (not shown) via a gasket 7. There is also a type in which an O-ring is provided on one end plate portion and is in contact with the filter housing via the O-ring. It is not essential that the gasket or O-ring be made of a polysulfone-based material because it can be easily attached and detached when it is disposed of. The filtered liquid is collected from a liquid collecting port of the core, and is discharged from a fluid outlet 8 provided at an end of the cylinder through a hollow portion of the core. Fluid outlets are provided at both ends of the cylinder, and fluid outlets are provided at only one end and one end is closed.

The microfiltration membrane 3 is made of an aromatic polyallyl ether sulfone (hereinafter referred to as a polysulfone polymer), and is preferable because it has excellent hydrophilicity, heat resistance and chemical resistance. Formulas 1 to 3 show typical chemical structures of the polysulfone-based polymer. The polymer shown in Chemical Formula 1 is sold by Amoco under the trade name Udel Polysulfone. On the other hand, a polyether sulfone represented by Chemical Formula 2 is sold by Sumitomo Chemical under the trade name of Sumika Excel PES. In the present invention, use of polyethersulfone is particularly preferred because of its particularly excellent chemical resistance. The method for producing a hydrophilic microporous microfiltration membrane made of a polysulfone-based polymer is disclosed in JP-A-56-154051, JP-A-56-86941,
JP-A-56-12640, JP-A-62-27006, JP-A-62-25870
No. 7, JP-A-63-141610 and the like.

[0007]

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[0008]

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[0009]

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[0010] The pore size of the filtration membrane is usually from 0.02 µm to 5 µm, but those having a display pore size of from 0.02 µm to 0.2 µm are preferably used in semiconductor manufacturing applications, particularly from 0.02 µm to 0.45 µm in the manufacture of highly integrated ICs. preferable. The properties of such a membrane can be expressed as a water bubble point value of 0.3 MPa or more as measured by the method of ASTM F316, and can be expressed as 0.1 to 1 MPa at an ethanol bubble point. Particularly preferably, the ethanol bubble point is 0.3 to 0.7 MPa. The larger the ratio of pores to the apparent volume of the membrane is, the smaller the filtration resistance is. On the other hand, if there are too many holes, the film strength is reduced and the film is easily broken. Therefore, a preferable porosity of the filtration membrane is 40%.
From 90%. Particularly preferred is 57% to 85%
It is. The film thickness is usually 30 μm to 220 μm. If the thickness is too large, the film area that can be incorporated into the cartridge decreases, while if it is too thin, the film strength decreases. Therefore, a particularly preferable film thickness is from 60 μm to 160 μm. A more preferred thickness is from 90 μm to 140 μm.

The microfiltration membrane 3 is sandwiched between the membrane supports 2 and 4 and is usually pleated by a known method. In the conventional pleated cartridge, a nonwoven fabric, a woven fabric, a net, or the like is used as the primary membrane support 2 and the secondary membrane support 4. The role of the membrane support is to reinforce the filtration membrane against fluctuations in filtration pressure, to permeate the liquid from the liquid supply side to the filtration side, and to introduce liquid into the back of the pleated pleats in a direction parallel to the filtration membrane. I also carry. Therefore, it is necessary to have appropriate liquid permeability and physical strength enough to protect the filtration membrane. Any sheet material having such a function can be used, but in the past, in most cases, a nonwoven fabric of polyester or polypropylene has been used because of its low cost and excellent performance. The membrane support that can be used in the present invention needs to be a material that has both heat resistance and chemical resistance in addition to the above general functions, and that can be incinerated. Accordingly, it is preferable that the material has the same or higher heat resistance and chemical resistance than that of the filtration membrane 3, and a polysulfone-based polymer having both heat resistance and chemical resistance is preferably used. However, since a polysulfone-based polymer fiber has not been manufactured, it is difficult to use a polysulfone-based polymer nonwoven fabric or woven fabric.

In the present invention, a microporous membrane made of a polysulfone-based polymer is used as a membrane support. The production method is basically the same as the microporous microfiltration membrane referred to in the present invention. Water bubble point of microporous membrane used for membrane support
It is preferably from 20 to 150 kPa, more preferably from 40 to 100 kPa. The water permeability in the direction perpendicular to the membrane support surface is preferably 150 ml / cm ² or more per minute when a differential pressure of 0.1 MPa is applied, and more preferably 200 ml / cm ² or more. Mullen burst strength of the membrane support is 80 kPa
It is preferably at least 120 kPa, more preferably at least 120 kPa. The method for providing grooves and / or protrusions on the membrane support is not particularly limited. This object can be achieved by emboss calendering, in which a microporous film is interposed between a metal roll having a large number of projections formed on its surface and a backup roll having a flat surface, and continuous pressing is performed. When a hard backup roll is used, only grooves are formed in the membrane support. When a soft backup roll is used, a projection is simultaneously formed on the opposite surface of the groove. Since the pores are crushed in the groove portions and the water permeability is lost, it is preferable that the area for forming the grooves is not more than half of the entire support film.

The grooves and / or protrusions provided on the membrane support may be provided only on one side of the support membrane or on both sides. Depth of unevenness given to membrane support is 5μm
From 0.25mm is available. Preferably from 20 μm to 0.1
It is 5 mm, particularly preferably 50 μm to 0.1 mm. The width of the grooves and peaks (hereinafter abbreviated as grooves) provided to the membrane support can be 5 μm to 1 mm. Preferably 20 μm
To 0.4 mm, particularly preferably 50 μm to 0.2 mm. The width and depth of the groove to be formed need not be constant everywhere. When grooves are formed, mutually independent circular or polygonal shapes are not preferable. A structure in which the grooves communicate and the liquid can flow in the plane direction is preferable. It is even more preferred if it is constituted by a number of longitudinal and transverse grooves which intersect each other. The distance between the grooves is preferably 4 mm or less even in a wide place, and 0.1 mm or less.
It is more preferable that the distance be 15 mm or more and 2 mm or less. The thickness of the microporous membrane used for the membrane support is preferably from 60 μm to 300 μm, particularly preferably from 100 μm to 220 μm. If it is too thin, the function of reinforcing the filtration membrane is inferior, and if it is too thick, the membrane area that can be incorporated into the cartridge is reduced, which is inconvenient.

In the present invention, it is also possible to use a membrane support in which holes are formed in a polysulfone-based polymer film and irregularities are formed on the front and back surfaces of the film by, for example, emboss calendering. The method of making a hole in the film is not particularly limited. For example, there are a method using a punch, a method using a sharp needle, a method using a laser, and a method using a water jet. The size of the hole can be a diameter or a size corresponding to a circle, an ellipse or a rectangle having a diameter or a side of 10 μm to 5 mm. Preferred hole sizes are 30 μm to 1.5 mm, particularly preferably 60 μm.
μm to 0.5 mm. The ratio of the hole area to the membrane support area can be used in the range of 10 to 90%. If the hole area ratio is too small, the filtration resistance will be too large, while if the hole area ratio is too large, the mechanical strength will be reduced and the microporous filtration membrane will not be reinforced. When drilling a large hole, a large hole area ratio is required, and when drilling a small hole, a relatively small hole area ratio is sufficient.

The depth or height of the unevenness provided to the film can be from 5 μm to 1 mm. Preferably 20 μm
To 0.4 mm, particularly preferably 50 μm to 0.2 mm. The height and depth of the unevenness to be formed need not be constant everywhere. The recesses formed in the film are not preferably circular, polygonal or other shapes independent of each other. A structure is required in which the concave portions communicate with each other so that the liquid can flow in the surface direction in the formed groove. It is even more preferred if it is constituted by a number of longitudinal and transverse grooves which intersect each other. The width of the groove is preferably in the range of 5 to 1000 μm, more preferably in the range of 20 to 400 μm, and particularly preferably in the range of 50 to 200 μm. The distance between the grooves is preferably 4 mm or less even at a wide place, and more preferably 0.15 mm or more and 2 mm or less.
Ideally, all previously drilled holes have grooves. Originally, the pattern of the convex portions formed on the opposite surface of the groove as the groove is formed may be either continuous and continuous with each other or may be isolated from each other. However, when embossing is performed, the convex portion and the concave portion have a front-to-back relationship. Therefore, a convex portion isolated when viewed from one surface forms a discontinuous isolated concave portion when viewed from the opposite surface, which is not preferable for use in the present invention. The thickness of the film used for the membrane support is from 25 μm to 1
It is preferably 25 μm, particularly preferably 50 μm to 100 μm. If it is too thin, the function of reinforcing the filtration membrane is inferior, and if it is too thick, pleating becomes difficult. A third membrane support that can be used is a net. The net is formed by spinning a monofilament having a diameter of 50 μm to 300 μm and knitting it. The monofilament used for the net is thicker and stronger than the non-woven yarn, so that it can be spun relatively easily. The smaller the yarn diameter, the thinner the finished net and the easier it is to pleate. On the other hand, if it is thin, spinning becomes difficult, and the strength of the completed net also decreases. Therefore, the preferred filament diameter is from 70 to 150 μm. The microporous filtration membrane is sandwiched on both sides by a membrane support, and pleated in this state by a usual method. At least one, and in some cases, a plurality of membranes can be used. At least one membrane support can be used on one side, and in some cases more than one membrane support can be used.

The pleated filter medium is trimmed with a cutter knife or the like in order to align both ends, and then rounded off into a cylindrical shape, and the seams of the joint are heat-sealed or liquid-tightly sealed with an adhesive. . The adhesive seal may be performed by combining the microfiltration membrane and the membrane support in total of six layers, or may be adhesively sealed so that the filter membranes directly overlap each other except for the support 2 or 4. The polysulfone sheet may be interposed between the folds and heat-sealed. As the adhesive or polysulfone sheet used here, the same material as the filtration membrane is preferable in order to improve the adhesiveness.
When an adhesive is used, the polysulfone-based polymer is used in a state of being dissolved in a solvent. For example, 10 parts of polyether sulfone is dissolved in a mixed solution of 30 parts of methylene chloride and 20 parts of diethylene glycol,
0 parts are gradually added and mixed. The solvent is heated and volatilized after bonding and does not remain in the filter cartridge.

The pleated body is obtained by inserting the core 5 inside the thus-formed cylindrical filter medium and covering it with the outer peripheral cover 1. The end sealing step in which both ends of the pleated body are liquid-tightly sealed to the end plate 6 is roughly classified into a method based on heat melting and a method based on solvent bonding.
In the hot melting method, only the sealing surface of the end plate is brought into contact with a hot plate, or only the surface is heated and melted by irradiating an infrared heater, and one end surface of the pleated body is pressed against the melting surface of the plate to perform adhesive sealing. In the case of the solvent bonding method, it is important to select a solvent. Usually, a solvent that does not dissolve the filtration membrane or has low solubility in the filtration membrane and is soluble in the end plate is selected. The solvent may be a single chemical species or a mixed solvent. When two or more solvents are mixed, at least the solvent having the higher boiling point does not have solubility in the filtration membrane. More preferably, the polymer is dissolved in the solvent adhesive in an amount of about 1% to 7%. For the polymer to be dissolved, select the same material as the end plate or at least a material that easily adheres to the end plate. The materials used for the membrane supports 2, 4, the core 5, the outer peripheral cover 1, and the end plate 6 must also have heat resistance and chemical resistance, and must be easily burnable. Therefore, a polysulfone polymer is preferably used. Polyethersulfone is particularly preferable because it has excellent heat resistance and chemical resistance and is relatively inexpensive. The materials of the members need not necessarily be the same as long as they can be bonded to each other, but the same materials are more preferable because they have good adhesiveness.
When all the materials are unified with polyether sulfone, the range of chemical resistance is widened, and it is particularly preferable in terms of adhesive sealability.

[0018] The filter cartridge thus obtained is used in the process of forming a hydrophilic microfiltration membrane or a microporous membrane for supporting a membrane, a solvent, a micropore-forming additive, and impurities in a polysulfone-based polymer. Remains or adheres to When such impurities are eluted in the filtrate, particularly in the chemical solution used in the semiconductor manufacturing process, the yield of the resulting semiconductor is reduced or the performance is reduced. As a result of intensive studies, the present inventors have found an inexpensive, efficient and effective method for cleaning organic contaminants. The method will be described in detail below.

The assembled filter cartridges are set one by one in the filter housing, and washing is performed while filtering ultrapure water through water. It is preferable that the liquid outlet of the filter cartridge is directed upward, since the washing water permeates at almost the same flow rate regardless of the upper and lower portions of the filter cartridge. Here, in order to make the washing more efficient, hot water ultrapure water is used at the initial stage of water passage. Water flow rate per 10-inch filter cartridge is 2 per minute
Liters to 10 liters are preferred. Even if water is passed at a flow rate of 10 liters or more per minute, the cleaning effect does not change, and the cost is high and the cost of hot ultrapure water is high. The higher the temperature of the hot water is 50 ° C. or higher, preferably 70 ° C. or higher, the higher the cleaning effect. However, if the temperature exceeds 100 ° C., it is difficult to control boiling, which is not preferable. Temperatures between 85 and 100 degrees C are most effective and relatively easy to handle. Normally, hot water flow is performed for 15 minutes to 120 minutes, and switching to cold water ultrapure water is performed, and the flow is completed at 3 to 10 minutes at a flow rate of 2 to 10 liters per minute. It goes without saying that the processing time and the temperature of the ultrapure water used depend on the degree of contamination of the filter cartridge. The higher the temperature of the ultrapure water, the higher the cleaning effect and the shorter the cleaning time. The necessary and sufficient conditions must be selected by measuring the cleaning effect. The washed filter cartridge is dried in a clean oven and is packaged clean.
Drying is performed at a temperature of 100 ° C. or less. If the drying temperature is high, the carbon component slightly remaining inside the members constituting the filtration membrane and the cartridge is likely to diffuse and emerge on the surface. Conversely, if the drying temperature is too low, it takes a long time to dry, which is not only inefficient, but also tends to produce a chance for fungi to propagate, which is rather undesirable. The preferred drying temperature is 60 to 85 degrees C.

Before the ultrapure water cleaning, dilute acid cleaning may be performed. In dilute acid washing, a plurality of filter cartridges are placed in a net basket, and the baskets are immersed together in a liquid filled with dilute acid, and treated with vibration for about 20 minutes or more and up to about 10 hours. Vibration may be any method as long as the integrity of the filter cartridge is not impaired.However, a method of stirring the liquid, a method of moving the basket up and down or horizontally, a method of applying ultrasonic vibration, and a method of once applying the liquid to the basket. There is a method of ascending above the surface, draining the liquid, and then immersing the liquid again.
If strong ultrasonic waves are applied for 10 minutes or more, the integrity of the filter is impaired. Therefore, the intensity of the ultrasonic waves must be determined after careful examination. The preferred acid used is
Hydrogen halides such as hydrochloric acid and bromic acid; organic carboxylic acids such as acetic acid and oxalic acid; nitric acid and sulfuric acid. Hydrogen halides that hardly remain on the filter after washing with ultrapure water and subsequent drying are preferable, and among them, general hydrochloric acid is particularly preferably used. As the acid concentration, a dilute acid having a concentration of 0.1N to 5N is preferably used. If the acid concentration is too low, the cleaning ability is inferior, and if the acid concentration is too high, the burden of rinsing the ultrapure water in the subsequent step becomes unnecessarily large and inefficient. Particularly, an acid having a concentration of 0.5N to 2N is preferably used. The higher the liquid temperature, the more effective, but on the other hand, there is a danger that the corrosion of the device is likely to occur and the contamination accompanying the corrosion of the device will adhere to the filter cartridge. At a high temperature, hydrogen halide gas is easily generated, and environmental management becomes difficult. Therefore, the liquid temperature is preferably in the range of 20 ° C to 40 ° C. The equipment that comes into direct contact with the dilute acid cleaning solution is made of a nonmetallic acid-resistant material. It is preferable to use a plastic material having high chemical resistance and heat resistance, such as a fluoropolymer, a polysulfone polymer, a polyolefin polymer, a polyimide polymer, or polycarbonate or polyphenylene sulfide. When the filter cartridge is extremely contaminated, it is preferable to replace the dilute acid solution with a fresh solution on the way.

When the acid washing for a predetermined time is completed, the filter is pulled up together with the basket above the liquid surface and left for several minutes to drain the liquid. Subsequently, the filter cartridge is immersed in the ultrapure water tank together with the basket, and vibration is applied. The vibration to be applied is the same as in the previous step. The temperature of ultrapure water is preferably the same as in the previous step. After being immersed in ultrapure water for 5 to 20 minutes, the filter is lifted together with the basket, the ultrapure water in the tank is replaced with new ultrapure water, and the filter is immersed again in ultrapure water.
Such immersion in ultrapure water is repeated two to four times. Since the acid concentration is reduced by rinsing and there is no need to worry about equipment corrosion, the temperature of ultrapure water in which the filter is finally immersed is 40 ° C.
It is preferable to set the temperature to a high temperature of at least 80 ° C. Since the filter cartridge manufactured in this manner hardly elutes TOC, the value indicated by the TOC meter decreases rapidly even when ultrapure water is filtered. However, no matter how clean it is during the manufacturing process, if the package is opened and exposed to air for loading into a filter, a small amount of hydrocarbon components present in the air will be adsorbed on the filter. Therefore, immediately after starting filtration of ultrapure water at a flow rate of about 8 liters per minute, the TOC component attached to the surface of the filter or the filter elutes,
The TOC value is inevitably higher than the TOC value of raw water ultrapure water. If the difference between the TOC value at the outlet of the ultrapure water supply device and the TOC value at the filter secondary side is called ΔTOC,
The TOC value can be from several tens ppb to 2
Indicates a value exceeding 00ppb. However, in the filter cartridge manufactured by the method of the present invention, the TOC value decreases rapidly, and drops to 5 ppb or less 10 minutes after the start of water flow.

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. (Example 1) A polyethersulfone film (Sumilite FS-1300, manufactured by Sumitomo Bakelite) having a thickness of 50 µm was applied to a 0.6 mm diameter.
Holes of 3 mm are punched out into a 2 cm × 2 cm area.
Using a soft resin roll for the back roll, groove width approx.
Emboss calendering is performed so that the distance between the grooves is 2 mm and the distance between the grooves is about 0.2 mm. At this time, the surface temperature of the embossing roll is 125 ° C., and the pressure is 100 kN / m. The film prepared in this manner is used as a primary-side membrane support. On the other hand, the nominal hole diameter
On one side of a 1.2 micron polyethersulfone microporous filtration membrane (Micro PES 12F manufactured by Membrana, ethanol bubble point value 36 kPa), the groove width is about 0.15 mm, the distance between grooves is 0.15 to 0.3 mm, and the depth is about 55 μm grooves are formed by emboss calendering. This is referred to as a secondary membrane support. 0.1 micron nominal diameter polyethersulfone microporous filtration membrane (Micro PES 1FP manufactured by Membrana)
H, ethanol bubble point value of 340 kPa) is pleated between the primary support and the secondary support. The interval between the folds is 10.5mm, the film width is 240mm, about 170
The membrane bundle folded at the mountain is cut, made into a cylindrical shape, and the folds at both ends are combined and heat-sealed. The polyethersulfone outer cover, core and end plate made by injection molding are annealed in advance at 180 ° C. for 5 hours and stored in a desiccator. The membrane bundle and the core are housed in this outer cover,
Make a pleated body with both ends aligned. The surface of the injection-molded polyethersulfone end plate is irradiated with an infrared heater, the surface of the end plate is heated to about 350 ° C. and melted, and the end of the pleated body that has been sufficiently preheated is pressed against and sealed with an adhesive. The opposite side of the pleated body is similarly sealed by welding the end plate to complete the filter cartridge. The resulting filter cartridge is washed in about 1N hydrochloric acid while slowly vibrating up and down for about 4 hours. Next, the wafer is immersed in ultrapure water for one hour while vibrating vertically, and then immersed in warm ultrapure water at 50 ° C. for about one hour while being similarly vibrated. Attach the filter cartridge to the filter, pass ultrapure water adjusted to 90 to 100 degrees C at a flow rate of 5 liters per minute for 60 minutes, and then flow ultrapure water at about 25 degrees C at a flow rate of 5 liters per minute. For 10 minutes. The filter cartridge thus washed was dried in a clean oven at 70 ° C. for 14 hours.

(Example 2) A filter cartridge was manufactured in the same manner as in Example 1 except that the cleaning time with hot ultrapure water was 15 minutes. (Example 3) A filter cartridge was manufactured in the same manner as in Example 1, except that the water temperature of the hot ultrapure water flow cleaning was 80 ° C and the water cleaning time was 30 minutes. (Comparative Example 1) A filter cartridge was manufactured in the same manner as in Example 1 except that water and water were washed with ultrapure water at a temperature of 40 ° C for 30 minutes instead of hot ultrapure water.

(Measurement of TOC recovery) The filter cartridge of the present invention of Examples 1 to 3 and the filter cartridge of Comparative Example 1 were loaded with a specific resistance of 18 MΩ / cm, a TOC value of 2 ppb,
Pass ultrapure water at a water temperature of 25 ° C at a flow rate of 8 liters per minute,
The primary and secondary TOC values were measured continuously. Table 1 shows the ΔTOC value 10 minutes after the start of water flow. All examples are 5pp
b, but the comparative example is far from 5 ppb.

[0025]

[Table 1]

[0026]

According to the present invention, when the all-polysulfone filter cartridge is assembled and washed by the method of the present invention, a microfiltration filter cartridge with little TOC elution, chemical resistance and easy incineration can be produced. it can.

[Brief description of the drawings]

FIG. 1 is a developed view showing a structure of a general pleated filter cartridge.

[Explanation of symbols]

 1. Peripheral cover 2. 2. Primary membrane support Microfiltration membrane 4. 4. Secondary membrane support Cores 6a, 6b. End plate 7. Gasket 8. Liquid outlet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA07 HA42 HA74 HA91 JA03A JA03B JA03C JA18C JA22Z JA27C JA30C JB01 JB06 JB07 JB08 MA03 MA22 MA24 MA31 MB09 MB11 MB12 MB13 MB16 MB20 MC62 MC63X NA54 NA64 PA01 PB12 PB13 PC01

Claims (2)

[Claims] 1. A microfiltration filter cartridge in which all of a hydrophilic microporous filtration membrane, a membrane support, a core, an outer peripheral cover and an end plate constituting a filter cartridge are made of a polysulfone-based polymer. 1 with hot ultrapure water of 50 ° C or more and 100 ° C or less
A method for producing a microfiltration filter cartridge, characterized in that it is washed with water for at least 5 minutes and then dried in a clean oven. 2. A microfiltration filter cartridge in which all of a hydrophilic microporous filtration membrane, a membrane support, a core, an outer peripheral cover and an end plate which constitute a filter cartridge are made of a polysulfone-based polymer. 1 with hot ultrapure water of 50 ° C or more and 100 ° C or less
When the filter cartridge is dried for 5 minutes or more and then dried in a clean oven, and ultrapure water having a specific resistance of 18 megohms is passed through the filter cartridge at a flow rate of 8 liters per minute per 10-inch cartridge. A microfiltration filter cartridge wherein ΔTOC in the ultrapure filtrate reaches 5 ppb or less within 10 minutes.