JP2002052320A - Precision filter cartridge and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precision filter cartridge having resistance to an acid, an alkali, an oxidizer, and a hot alcohol, freed from air lock because of its hydrophilic filter membranes, and being capable of easily incinerated when it becomes wastes and to provide a method for producing the same. SOLUTION: There is provided a precision filter cartridge wherein all of the hydrophilic microporous membranes, membrane supports, cores, peripheral covers, and end plates that constitute the cartridge are made from a polysulfone polymer and prepared by immersing it after being assembled in a dilute acid solution for at least 2 hr and washing the assemblage by passing it through ultrapure water and a method for producing the same. A higher effect can be attained by intervening the immersion of the assemblage in a dilute acid solution between the its immersion in hot water at 50-90 deg.C and its washing by passing it through ultrapure water.

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. Therefore, in order to filter the cleaning solution, it is required to use a material having high chemical stability which is not affected by the cleaning solution. Conventionally, for filtration of such a chemical solution, a microporous microfiltration membrane made of polytetrafluoroethylene (PTFE) is used as a filtration member,
A filter for filtration using a fluorine-based polymer is used for other filter components. But PTF
The E-filtration membrane is very hydrophobic, so it is necessary to pre-wet with 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 solution to replace it. There was a lot of unnecessary waste liquid. In addition, even if such a modification is applied to wet the membrane and start filtration, there is a problem that airlock is easily caused by entry of a small amount of air bubbles and often filtration cannot be performed. In addition, when the used fluorine-based polymer filter is disposed of, there is a problem that toxic gas is generated 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. And a mixture of hydrogen peroxide and dilute hydrofluoric acid, a mixture of hydrofluoric acid and ammonium fluoride, a mixture of hydrofluoric acid and hydrogen peroxide, or a mixture of ammonia and hydrogen peroxide, and An object of the present invention is to provide a filter cartridge that does not involve an air lock and that can easily incinerate a used filter.

To this end, the present inventor has previously filed a patent application by developing a hydrophilic microfiltration filter cartridge, a so-called all-polysulfone filter, in which all the constituent materials are made of a polysulfone-based polymer (Japanese Patent Application No. Hei 10-284,197). 11-156798). This filter has a remarkable improvement effect on the above-mentioned problems related to the microfiltration, but the microfiltration membrane using the polysulfone-based polymer easily adsorbs metal ions in the film forming process and adsorbs metal ions. Using a filter as it is in the semiconductor manufacturing process has another problem in that even a small amount of adsorption can degrade the performance of the semiconductor and is dangerous. Is desired. Therefore, a second object of the present invention is to provide a filter cartridge that satisfies the first object and that is free from metal ion impurity adsorption contamination.

[0005]

The objects of the present invention have been attained by the following inventions. (1) In the microfiltration filter cartridge in which all the constituent members 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 polysulfone-based polymer, A method for manufacturing a microfiltration filter cartridge, comprising assembling a member into a filter cartridge, immersing the filter cartridge in a dilute acid solution for at least 2 hours, and then washing the filter cartridge with ultrapure water.

(2) Between the immersion treatment for at least 2 hours in a dilute acid solution and the washing with passing pure water, the temperature is between 50 ° C. and 90 ° C.
The method for producing a microfiltration filter cartridge according to the above (1), characterized by performing the following immersion treatment in hot water.

(3) A microfiltration filter cartridge manufactured by the manufacturing method according to (1) or (2).

[0008]

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 plate laminated cartridge, for example, JP-A-63-80815, JP-A-56-129016, and 58-98111
It is disclosed in publications such as 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 cartridge filter. Microfiltration membrane 3
Is folded while being sandwiched by two membrane supports 2 and 4 and wound around a core 5 having a large number of liquid collecting ports. An outer cover 1 is provided on the outside of the outer cover 1 to protect the microfiltration membrane 3. The microfiltration membrane 3 is sealed at both ends of the cylinder by end plates 6a and 6b. The end plates 6a and 6b are 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. Gaskets or O-rings can be easily removed when the filter cartridge is discarded,
It is not essential to be made of a polysulfone-based material.
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. In the following description of the present invention, the numbers assigned to the respective members of the cartridge filter are the member numbers of the respective members in FIG.

The microfiltration membrane 3 is preferably a membrane made of a halogen-free polymer such as aromatic polyarylethersulfone, polyolefin or polyamide.
Among them, a hydrophilic film made of an aromatic polyaryl ether sulfone (hereinafter referred to as a polysulfone-based polymer) is preferable because of its excellent heat resistance and chemical resistance. .
Typical chemical structures of the polysulfone-based polymer are shown in the following general formulas 1 to 3. The polymer represented by the general formula 1 is sold by Amoco under the trade name Udel Polysulfone. On the other hand, polyether sulfone represented by the general formula 2 is sold by Sumitomo Chemical Co., Ltd. under the trade name of Sumika Excel PES. Polyether sulfone is particularly preferably used in the present invention because of its particularly excellent chemical resistance. A method for producing a hydrophilic microporous microfiltration membrane using a polysulfone-based polymer is disclosed in JP-A-56-154051, JP-A-56-14056.
No. 86941, JP-A-56-12640, JP-A-62-27006, JP-A-62-258707, JP-A-63-141610 and the like.

[0010]

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The pore size of the filtration membrane is usually from 0.02 μm to 5 μm, but a pore size of 0.02 μm to 0.45 μm is preferably used in semiconductor manufacturing applications, and in particular, a display pore size of 0.02 μm to 0.2 μm in highly integrated IC production. 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, the preferred porosity of the filtration membrane is 40
% To 90%. Particularly preferred is 57% to 85%
%. 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 pleated by a generally 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 heat resistance and chemical resistance in addition to a general filtration function, and that can be incinerated. Therefore, it is preferable to use a halogen-free polymer having the same heat resistance and chemical resistance as the same material as or higher than that of the filtration membrane 3. Among them, polysulfone polymers are particularly preferable because they have both heat resistance and chemical resistance.
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 (not a woven or nonwoven fabric) 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. The water bubble point of the microporous membrane used for the membrane support 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 per minute. The Mullen rupture strength of the membrane support is preferably at least 80 kPa, more preferably at least 120 kPa.

The method of 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 a continuous compression treatment 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 at 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 to the membrane support may be provided only on one side of the support film, or may be provided 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 the polysulfone-based polymer film and irregularities are formed on the front and back surfaces of the film by, for example, emboss calendering. The method for perforating 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 circle, an ellipse, or a rectangle whose diameter, major axis, or major side is from 10 μm to 5 mm. In the case of an ellipse or rectangle, the minor axis or minor side is the major axis or major side, respectively. At least one tenth). Preferred hole size is 30
It is from μm to 1.5 mm, particularly preferably from 60 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 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 25
It is preferably from μm to 125 μm, particularly preferably from 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. Net is 50μm to 300μ in diameter
It can be made by spinning m monofilament 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. Use at least one microporous filtration membrane,
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 at both ends with a cutter knife or the like in order to align both ends, then rounded 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 core 5 inserted into the cylindrical filter medium thus formed and covered with the outer peripheral cover 1 is called a pleated body. The end sealing step in which both ends of the pleated body are liquid-tightly bonded and sealed to the end plate 6 can be broadly 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 and 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, halogen-free polymers such as polysulfone-based polymers, polyolefins and polyamides are preferred as materials. Among them, a polysulfone-based polymer material is preferable, and polyethersulfone is particularly preferable because it is excellent in heat resistance and chemical resistance and relatively inexpensive. The materials of the respective members are not necessarily required to be the same as long as they can be bonded to each other, but the same material is more preferable because of good adhesiveness. When all the materials are unified with polyethersulfone, the range of chemical resistance is widened, and it is particularly preferable in terms of adhesive sealability.

The filter cartridge prepared in this manner completely eliminates trace amounts of metal ions and organic substances such as sodium and calcium which the polysulfone-based polymer has as impurities, metal fine powder and organic substance contamination attached in the filter cartridge assembly process. Cleaning must be performed to remove them. As a result of intensive studies, the present inventors have found a method that is inexpensive, can quickly remove metal ions to a trace level (harmless level), and can effectively clean organic contaminants at a high removal rate. The method will be described in detail below. The dilute acid immersion, which is performed first, involves placing a plurality of filter cartridges in a net basket, immersing the baskets together in a liquid filled with dilute acid, and treating with vibration for about 2 hours 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 mechanically stirring the liquid, a method of moving the basket vertically or horizontally, a method of applying ultrasonic vibration,
There is a method in which the basket is once raised above the liquid level, drained, and then immersed again in the liquid. 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. It goes without saying that the processing time and the method and degree of vibration should be adjusted according to the degree of contamination of the filter cartridge. Therefore, it is preferable to measure the cleaning effect and select necessary and sufficient cleaning conditions based on the measurement.

Preferred acids to be used are hydrogen halides such as hydrochloric acid and bromic acid, organic carboxylic acids such as acetic acid and oxalic acid, nitric acid and sulfuric acid. Among them, hydrogen halides which 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. Especially 0.5
Acids with a defined to up to 2N concentration are 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. If the filter cartridge is extremely contaminated, it is preferable to replace the dilute acid solution with fresh solution during the washing process. When the acid washing for a predetermined time is completed, the filter together with the basket is pulled up on the liquid surface and left for a few 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. By repeating the rinsing, the acid concentration of the washing water is reduced and there is no fear of apparatus corrosion. Therefore, the temperature of the ultrapure water in which the filter is finally immersed is preferably set to a high temperature of 40 ° C. or more and 80 ° C. or less.

Next, the filter cartridges are set one by one in the filter housing, and the washing is continued while ultra pure water is passed through and filtered. 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. Water supply is continued until the specific resistance value of the ultrapure water that has passed through the filter cartridge reaches the same theoretical ultrapure water level as the raw water within the range of the measurement error. Here, in order to make the washing more efficient, hot water ultrapure water is used in the initial stage of water passage. The flow rate of water per 10-inch filter cartridge is preferably 2 to 10 liters per minute. 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 temperature of hot water is 50 ° C or higher, and the higher the water temperature, the higher the cleaning effect. However, if the temperature exceeds 100 ° C., it is difficult to control boiling, which is not preferable. A temperature around 85 degrees C is the easiest and most effective. Normally, hot water is passed through for 30 to 60 minutes, then switched to cold ultrapure water and the flow rate is reduced from 5 liters per minute.
At 10 liters, continue water flow until the specific resistance of the filtrate reaches the theoretical ultrapure water level. Normally, it can be completed by passing water for 10 to 30 minutes.

[0025]

(Example 1) Ethanol bubble point 25 was determined using Sumica Excel PES (manufactured by Sumitomo Chemical Co., Ltd.) by the method described in JP-A-63-139930.
A 0 kPa polyethersulfone membrane was formed and used as a microporous filtration membrane (referred to as membrane A). On the other hand, JP-A-63-139
A polyether sulfone membrane having an ethanol bubble point of 50 kPa was formed by the method described in Example 3 of JP-A-930. This film is called film B. Approximate groove width on one side of membrane B
0.15mm, spacing between grooves 0.15 to 0.3mm, depth about 5
5 μm grooves are formed by emboss calendering. This membrane C was used as a membrane support.

A pleating process was performed by a usual method with the film A interposed between the two films C. The surface of the film C in contact with the film A was a flat surface on which neither the primary film C nor the secondary film C had a groove. Pleated fold spacing is 10.5m
m, the membrane width was 240 mm, and the membrane bundle folded at about 170 peaks was cut, made cylindrical, and heat-sealed by fitting the folds at both ends. The membrane bundle and the polyethersulfone core were housed in a polyethersulfone outer peripheral cover, and both ends were aligned to produce a pleated body. Irradiate an infrared heater to the surface of the end plate made by cutting out a polyether sulfone round bar, heat the end plate surface to about 350 ° C, melt it, and press the end of the pleated body that has been sufficiently preheated to bond Sealed. The other side of the pleated body was similarly sealed by welding the end plate to complete the filter cartridge. The dimensions of the outer cover and the core window were 1.8 mm in the axial direction and 22 mm in the circumferential direction. cover,
Core and end plate are Sumika Excel PES3
Molded using 600G.

The filter cartridge thus prepared is placed in a net basket, and the basket is immersed in a 0.5 N hydrochloric acid aqueous solution. The basket is moved up and down and horizontally in a cycle of 2 seconds using a vibrator to stir. While soaking, an acid immersion treatment was performed for about 3 hours. During that time, the liquid temperature was kept in the range of 35 ° C. ± 4 ° C. After the completion of the acid cleaning for a predetermined time, the filter together with the basket was pulled up on the liquid surface, and left for several minutes to drain the liquid.
Subsequently, the filter cartridge was immersed in the ultrapure water tank together with the basket, and washed while applying vibration in the same manner as in the previous step. The temperature of ultrapure water was the same as in the previous step. After immersing in ultrapure water for 10 minutes, pull up the filter with the basket,
The ultrapure water in the tank was replaced with new ultrapure water, and the filter was immersed in the ultrapure water again. Such immersion in ultrapure water was repeated three times, but the third washing was performed at a water temperature of 60 ° C.

Next, the filter cartridges were set one by one in the filter housing, and the washing was continued while filtering the ultrapure water with water, and the filtration was continued until the specific resistance of the ultrapure water permeated through the filter cartridge reached 18 MΩcm. Water was continued to complete the filter cartridge for microfiltration.

Example 2 Ultrapure water (hot water) after acid cleaning
A filter cartridge for microfiltration was completed in the same manner as in the example, except that the filter cartridge was set in the filter housing and washed with water, without performing immersion treatment. However, the amount of water required to reach the specific resistance value of the ultrapure water permeating the filter cartridge of 18 MΩcm was twice as long and the required time was twice as long.

(Comparative Example) Example 1 is the same as Example 1 except that the filter cartridge was set in the filter housing without passing through acid cleaning and immersion in ultrapure water (warm water). A filter cartridge for microfiltration was completed in the same manner as described above.

The filter cartridges of Examples 1, 2 and Comparative Examples were each immersed in 1.5 L of 0.5 mol / L hydrochloric acid at room temperature for 24 hours, and the concentration of metal ions eluted in hydrochloric acid was determined. As a result of measurement, in Examples 1 and 2, both Na ion and Ca ion were 2 ppb or less, but in Comparative Example, Na ion was about 50 ppb,
Ca ion was about 20 ppb.

[0032]

After assembling the all-polysulfone filter cartridge as in the present invention, if the cleaning process is performed by the method of the present invention, the semiconductor can be rinsed with about half the conventional ultrapure water rinsing time and about half the conventional ultrapure water consumption. It is possible to produce a microfiltration filter cartridge which is applicable to the manufacturing process and has cleanliness, chemical resistance and easy incineration treatment.

[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 HA74 HA91 JA03A JA03B JA03C JA10C JA19C JA22A JA22C JA23C JA27C JA30C JB06 JB07 JB13 MA03 MA06 MA22 MA24 MA31 MB02 MB09 MB11 MB12 MB16 MB20 MC22 MC54 MC63X NA47 NA12 NA01 PA01 4F073 AA01 AA13 BA32 BB02 EA03 EA11 EA31 EA34

Claims (3)

[Claims] 1. A microfiltration filter cartridge in which all the constituent members of a hydrophilic microporous filtration membrane, a membrane support, a core, an outer peripheral cover and an end plate which constitute the filter cartridge are made of a polysulfone-based polymer. A method for manufacturing a microfiltration filter cartridge, comprising assembling each component into a filter cartridge, immersing the filter cartridge in a dilute acid solution for at least 2 hours, and then washing the filter cartridge with ultrapure water. 2. A process of immersing in hot water of 50 ° C. or more and 90 ° C. or less between the immersion treatment in a dilute acid solution for at least 2 hours and the washing with ultrapure water. Claim 1
A method for producing the microfiltration filter cartridge according to the above. 3. A microfiltration filter cartridge produced by the production method according to claim 1.