JP2001353427A - Method for manufacturing microfiltration filter cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which perfectly manufactures a filter cartridge of which all constituents are made of polysulfone polymer without generating fine bubbles in an end plate which is one of the constituents in the manufacture process. SOLUTION: In this manufacture of microfiltration filter cartridge which is composed of a microporous filter membrane, a membrane support, a core, an outer peripheral cover and an end plate and in which all of the constituents are made of polysulfone type polymer, the end plate is subjected to dry processing beforehand and, thereafter, is subjected to thermal melt-sticking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a filter cartridge using a microporous filtration membrane. More specifically, a filter cartridge that is excellent in chemical resistance and filtration stability and does not generate toxic gas during incineration disposal treatment, is to produce microbubbles on the end plate, one of the components in the manufacturing process. And a method that can be manufactured with high integrity.

[0002]

2. Description of the Related Art In recent years, in the production of semiconductors, there has been a demand for a filter for filtration which has high resistance to chemicals such as organic solvents, acids, alkalis and oxidizing agents and has a small amount of eluted substances. At present, for filtering such a chemical solution, a microporous microfiltration membrane made of polytetrafluoroethylene (PTFE) is used, and a filter cartridge using a fluorine-based polymer for other filter cartridge components, that is, a so-called filter cartridge. An all-fluorine filter cartridge is used. However, in this all-fluorine filter cartridge, the filtration membrane made of PTFE is extremely hydrophobic, and even if it is moistened with an alcohol such as isopropanol at the beginning of the filtration, air bubbles are generated due to the incorporation of a slight amount of air bubbles, making it impossible to filter. Thus, there is a problem that filtration stability is lacking. There is also a problem that toxic gas is generated when the used filter cartridge is incinerated and disposed of.

A problem with the above-mentioned conventional all-fluorine filter cartridge is that all components of the microporous filtration membrane, the membrane support, the core, the outer peripheral cover and the end plate constituting the filter cartridge are made of a polysulfone-based polymer. Can be solved. The microporous filtration membrane made of a polysulfone-based polymer is hydrophilic, and does not cause air lock due to the incorporation of a small amount of air bubbles, and has excellent filtration stability. Also,
A filter cartridge in which all of the above components are made of a polysulfone-based polymer does not generate toxic gas even after incineration disposal. Needless to say, the polysulfone-based polymer is a material having excellent chemical resistance, and a filter cartridge in which all of the above components are made of the polysulfone-based polymer has excellent chemical resistance.

However, in a filter cartridge in which all of the above components are made of a polysulfone-based polymer, microbubbles are generated in an end plate which is one of the components during the manufacturing process, and the filter cartridge to be manufactured is manufactured. There is a problem that integrity is lost.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a filter cartridge in which all the components are made of a polysulfone-based polymer by using an end plate which is one of the components in the manufacturing process. It is an object of the present invention to provide a method which can be manufactured with high integrity without generating microbubbles.

[0006]

In order to achieve the above object, the present invention comprises a microporous filtration membrane, a membrane support, a core, an outer peripheral cover and an end plate, and all of the above components are made of polysulfone. In producing a microfiltration filter cartridge made of a polymer, the present invention provides a method for producing a microfiltration filter cartridge, which comprises subjecting the end plate to drying treatment in advance and then subjecting the end plate to heat welding. Hereinafter, the present invention will be described in detail.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a filter cartridge comprises a microporous filtration membrane, a pleated cartridge having a structure in which a membrane support for protecting the filtration membrane is folded in a pleated form, and a plurality of flat plate filtration units. Are known. An example of the structure of a pleated cartridge is disclosed in
Nos. 235722 and 10-66842. Examples of the structure of a flat plate type cartridge are disclosed in, for example, JP-A-63-8081.
Nos. 5, 56-129016 and 58-98111
No. and other publications. The manufacturing method of the present invention is applicable to any of the above types of filter cartridges. . In addition, the manufacturing method of the present invention can be performed according to a conventional manufacturing method of a filter cartridge, except that the end plate is subjected to a heat treatment after being dried in advance.

Hereinafter, the structure of the pleated type cartridge will be described in more detail with reference to FIG. FIG.
FIG. 1 is a development view showing the entire structure of a general pleated microfiltration filter cartridge. In this filter cartridge, generally, the microporous filtration membrane 3 is folded while being sandwiched by two membrane supports 2 and 4, and is wound around a core 5 having a large number of liquid collection ports. On the outside, there is an outer peripheral cover 1 having many liquid supply ports, and protects the microporous filtration membrane 3.
The microporous filtration membrane 3 is sealed at both ends of the cylinder constituted by the above-mentioned elements by end plates 6a and 6b. The end plate 6a contacts 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. The gasket or O-ring can be easily removed when disposing. The filtered liquid is collected from the liquid collecting port of the core 5 and discharged from the liquid outlet 8 provided at the end of the cylinder through the hollow part of the core 5. There are a type in which the liquid outlet is provided at both ends of the cylinder, and a type in which the liquid outlet is provided only at one end and one end is closed.

In the present invention, a hydrophilic microporous microfiltration membrane made of a polysulfone-based polymer such as aromatic polyallyl ether sulfone is used as the microporous filtration membrane 3. Among the polysulfone-based polymers, polyethersulfone is preferably used because it has a wider range of chemical resistance. Representative examples of the polyether sulfone include polymers represented by the following general formulas (I), (II) and (III).

[0010]

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Among the polymers represented by the general formula (I), there is a polymer sold by Amoco under the trade name of Udelpolysulfone. The polymer represented by the general formula (II) includes a polymer sold by Sumitomo Chemical under the trade name of Sumika Excel PES. Further, a method for producing a hydrophilic microporous microfiltration membrane using a polysulfone-based polymer as a material is described in JP-A-56-154051, JP-A-56-86941.
No., JP-A-56-12640, JP-A-62-2700
No. 6, JP-A-62-258707, JP-A-63-14
No. 1610 and other publications.

The pore size of the microporous filtration membrane 3 is usually 0.0
It is 2 μm to 5 μm, but is 0.0
Those having a diameter of 2 μm to 0.45 μm are preferably used, and those having a display hole diameter of 0.02 μm to 0.2 μm are particularly preferable in the production of highly integrated ICs. The properties of such a membrane are
The water bubble point value measured by the method of ASTM F316 is 0.3 MPa or more, and the ethanol bubble point is 0.1 to 1 MPa. Particularly preferably 0.3 to 0.7MP at ethanol bubble point
a. In addition, it is preferable that the ratio of the pores to the apparent volume of the membrane is large because the filtration resistance is small. On the other hand, if there are too many holes, the film strength is reduced and the film is easily broken. Therefore, the porosity of the preferred 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.
0 μm, and more preferably 90 μm to 14 μm.
0 μm.

The microporous filtration membrane 3 is pleated by a generally known method, sandwiched between the membrane supports 2 and 4. These membrane supports 2 and 4 are also similar to the microporous filtration membrane 3,
A material made from a polysulfone-based polymer is used. As a material for the membrane support, polyether sulfone is preferably used among polysulfone polymers. For pleating, the microporous filtration membrane used is
At least one, and in some cases, a plurality of microporous filtration membranes can be used. At least one membrane support may be used on one side, and in some cases, a plurality of membrane supports may be used. The role of the membrane support is to reinforce the filtration membrane against fluctuations in filtration pressure, and at the same time to play a role of introducing liquid into the fold. Therefore, it is necessary to have appropriate liquid permeability and physical strength enough to protect the filtration membrane. In the present invention, various forms of the membrane support can be used as long as they have such a function, and the following forms of the membrane support can be used.

That is, in the present invention, first, a non-woven fabric or a woven fabric made of a polysulfone-based polymer can be used as a membrane support. This non-woven fabric or woven fabric has a thickness of 50 μm when measured with a screw micrometer.
To 600 μm, more preferably 80 to 350 μm, and the basis weight is 15 g.
/ M ² to 100 g / m ² , more preferably 20 g / m ² to 50 g / m ² . If it is too thin, the strength is insufficient, and if it is too thick, the required area of the filtration membrane that can be accommodated in the cartridge cannot be secured.

In the present invention, a microporous membrane made of a polysulfone polymer can be used as a membrane support. The production method is basically the same as the production method of the microporous microfiltration membrane. 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. Water permeability perpendicular to the membrane support surface is
The water flow rate when a differential pressure of 0.1 MPa is applied is 1 per minute.
It is preferably at least 50 ml / cm ^2, more preferably at least 200 ml / cm ² . The Murren burst strength of the membrane support is preferably 80 kPa or more, and 120 kP
It is more preferable that the value is equal to or more than a.

The microporous film is usually used as a film support by forming a large number of fine grooves and / or convex portions. The method for providing grooves and / or protrusions on the microporous membrane is not particularly limited. For example, by performing an emboss calendering process that continuously press-bonds a microporous film between a metal roll having a large number of protrusions formed on the surface and a backup roll having a flat surface, a desired groove is formed on the microporous film. And / or a convex part can be suitably provided. When a hard backup roll is used, only grooves are formed in the microporous membrane. When a soft backup roll is used, a protrusion is simultaneously formed on the opposite surface of the groove. In general, the pores are crushed in the groove portions and the water permeability is lost. Therefore, it is preferable that the groove formation area be equal to or less than half of the entire microporous membrane used as the membrane support.

The grooves and / or projections provided on the microporous film may be provided on only one surface of the microporous film, or may be provided on both surfaces. The depth of the irregularities imparted to the microporous membrane is 5 μm
To 0.25 mm can be used, preferably 20 μm
m to 0.15 mm, particularly preferably 50 μm to 0.1 mm. The width of the grooves and peaks (hereinafter simply referred to as “grooves”) provided to the microporous membrane can be 5 μm to 1 mm, preferably 20 μm to 0.4 mm, and particularly preferably 50 μm to 0.2 mm. It is. 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 5 mm or more and 2 mm or less. The thickness of the microporous film 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, a film made of a polysulfone-based polymer as a membrane support is perforated,
In addition, a film having irregularities on the front and back sides of the film by, for example, emboss calendering may be used. 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 is 10 mm in diameter or one side
A size corresponding to a circle, an ellipse or a rectangle from μm to 5 mm can be used. Preferred hole size is 30μ
m to 1.5 mm, particularly preferably 60 μm to 0.5 mm. The ratio of the hole area to the film area is 1
It can be used in the range of 0 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. It is preferably from 20 μm to 0.4 mm, particularly preferably 50 μm.
m 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 μm to 1000 μm, more preferably in the range of 20 μm to 400 μm, and particularly preferably in the range of 50 μm 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, grooves are connected to all of the drilled holes. The pattern of the convex portions formed on the opposite surface of the groove with the formation of the groove is originally connected to each other, even if it is continuous,
They may be present separately from each other. However, when the embossing is performed, the convex portion and the concave portion have a front-to-back relationship. Therefore, a convex portion that is isolated when viewed from one surface forms a discontinuous and isolated concave portion when viewed from the opposite surface, which is not preferable as a pattern of unevenness to be provided. The thickness of the film used for the membrane support is preferably from 25 μm to 125 μm, and 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.

Further, in the present invention, a net made of a polysulfone polymer can be used as a membrane support. This net can be produced by spinning a polysulfone-based polymer into a monofilament having a diameter of 50 μm to 300 μm and knitting it. Since the monofilament used for the net is thick and strong as compared with the nonwoven fabric yarn, it can be spun relatively easily. The smaller the yarn diameter, the thinner the finished net becomes and the easier it is to pleate. On the other hand, if the yarn diameter is small, spinning becomes difficult, and the strength of the completed net also decreases. Thus, the preferred filament diameter is between 100 μm and 200 μm.

The pleated filter medium composed of the microporous filtration membrane and the membrane support is cut off with a cutter knife or the like in order to align both ends, and is generally rounded into a cylindrical shape. The eye folds are generally sealed liquid tight using heat sealing or an adhesive. This adhesive seal can be performed by combining a total of six layers of the microporous filtration membrane 3 and the membrane supports 2 and 4, and the adhesive seal is performed so that the filtration membranes directly overlap each other except for the membrane supports 2 and 4. You can also. Heat sealing may be performed with a thermoplastic sheet interposed between the folds. The thermoplastic sheet used here is also required to have heat resistance and chemical resistance.
Therefore, the use of polysulfone-based polymer materials is preferred,
Particularly, use of polyether sulfone is preferred. When an adhesive is used, the polysulfone-based polymer adhesive is used in a state of being dissolved in a solvent. For example, polyether sulfone 1
0 parts are 30 parts of methylene chloride and 20 parts of diethylene glycol.
Of the mixed solution, and 140 parts of diethylene glycol are gradually added and mixed. The solvent is heated and volatilized after bonding so that it does not remain in the filter cartridge.

The core 5 is inserted into the inside of the cylindrical filter medium formed as described above, and is covered with the outer peripheral cover 1 to produce a so-called pleated body. An end sealing step of liquid-tightly sealing both ends of the pleated body with the end plate 6 includes:
It is often performed by heat welding by a hot melting method. In the heat melting method, only the sealing surface of the end plate is brought into contact with the 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 end plate and bonded by heat welding. Seal. The hot-melt method does not require auxiliary materials such as an adhesive, and can easily perform the above-mentioned adhesive sealing.

In the present invention, the core 5 and the outer cover 1 are used.
The end plate 6 is made of a polysulfone-based polymer as in the case of the microporous filtration membrane 3 and the membrane supports 2 and 4. Polyethersulfone is preferably used among the polysulfone-based polymers as a material for each of the above components. It is particularly preferable to unify the materials of all the constituent elements with polyethersulfone from the viewpoints of widening chemical resistance and adhesive sealability.

The end plate 6 is mainly formed by injection molding. In some cases, a plate obtained by punching or shaving a disk from an extruded thick plate is used. The end plate thus produced contains moisture inside.Therefore, in order to perform the heat welding of the end plate in the above-mentioned end sealing step, when the sealing surface of the end plate is melted at a high temperature, the moisture contained therein becomes gas. And foaming, creating microbubbles in the end plate, which compromises the integrity of the manufactured filter cartridge. The foaming of the moisture contained in the end plate during the heat welding can be prevented by previously drying the end plate to remove the contained moisture. Therefore, in the practice of the present invention, the end plate is subjected to heat welding after drying treatment in advance.

The pre-drying process is performed under the following conditions. That is, the drying temperature is generally 120 ° C. to 210 ° C.
Do between. The temperature of 140 ° C. to 170 ° C. is preferable for the polyether sulfone represented by the general formula (I).
Although the processing time varies depending on the drying temperature, it requires at least 2 hours, and preferably at least 4 hours. For example, 160 ° C
When drying for 5 hours or more, it is perfect and particularly preferable. The temperature of the polyether sulfone represented by the general formula (II) is preferably from 150 ° C. to 200 ° C.
Particular preference is given to between 190C and 190C. Although the processing time varies depending on the drying temperature, it requires at least 2 hours, and preferably at least 4 hours. For example, when drying at 180 ° C., 5 hours or more is perfect and particularly preferable. It is needless to say that it is not essential, but preferable, to perform the same drying treatment as the end plate on a hot melt molded member such as an injection molded member or an extrusion molded member other than the end plate.
It is preferable that the end plate and other members after the drying process are managed so as not to absorb moisture again in, for example, a desiccator until they are used for assembling the filter cartridge.

[0026]

The present invention will be described more specifically with reference to the following examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 Udel polysulfone P-35 manufactured by Amoco Co., Ltd. was prepared by the method described in Example 1 of JP-A-63-139930.
Then, a polysulfone membrane having an ethanol bubble point of 250 kPa was formed by using 00, and this was used as a microporous filtration membrane (referred to as membrane A). On the other hand, a polysulfone membrane having an ethanol bubble point of 50 kPa was formed using the same Udel polysulfone P-3500 by the method described in Example 3 of JP-A-63-139930 (referred to as membrane B). On one surface of the film B, a groove having a groove width of about 0.15 mm, an interval between grooves of 0.15 to 0.3 mm, and a depth of about 55 μm was formed by emboss calendering (referred to as a film C). Using this film C as a film support, two films C
Was pleated by a usual method with the film A interposed therebetween. The film C was in contact with the film A on a flat surface on which neither the primary film C nor the secondary film C had a groove. The interval between the folds was 10.5 mm, the film width was 240 mm, and the film bundle folded at about 120 peaks was cut, cylindrically formed, and heat-sealed by fitting the folds at both ends. A membrane bundle and a polysulfone core were housed in a polysulfone outer peripheral cover made of the same polysulfone resin which was previously dried in a desiccator by drying at 160 ° C. for 5 hours, and both ends were aligned to form a pleated body. . The surface of the polysulfone end plate previously dried in a desiccator by drying at 160 ° C. for 5 hours was irradiated with an infrared heater, and the surface of the end plate was heated to about 300 ° C. to be melted and sufficiently heated. The end of the pleated body was pressed and sealed by adhesion. The other side of the pleated body was similarly sealed by welding the end plate to complete the filter cartridge. The outer peripheral cover and the end plate are manufactured by injection molding. There are almost no air bubbles that can be visually confirmed at the end plate welded part of this completed filter cartridge,
It also passed the integrity test.

Example 2 Three holes having a diameter of 0.6 mm were punched out of a 50 μm thick polyethersulfone film (Sumilite FS-1300 (trade name) manufactured by Sumitomo Bakelite Co., Ltd.) in an area of 2 cm × 2 cm. Was. Using a soft resin roll for the back roll, a groove width of about 0.
Emboss calendering was performed so that the distance between the grooves was 2 mm and the distance between the grooves was about 0.2 mm. At this time, the surface temperature of the embossing roll was 125 ° C., and the pressing was 100 kN / m. This embossed calendered perforated film is used as a membrane support, and between the two films, a polyethersulfone microporous filtration membrane having a nominal pore size of 0.1 μm (Micro PES 1FPH (trade name) manufactured by Membrana Co., Ltd.) It was pleated with an ethanol bubble point value of 340 kPa). The fold interval is 10.5mm,
The film bundle having a film width of 240 mm was cut at about 140 peaks, cut into a cylindrical shape, and heat-sealed by fitting the folds at both ends. The membrane bundle and the polyethersulfone core were accommodated in a polyethersulfone outer peripheral cover, and both ends were aligned to form a pleated body. The surface of the end plate made of polyethersulfone, which was previously dried at 180 ° C. for 5 hours and stored in a desiccator, was irradiated with an infrared heater, and the surface of the end plate was heated to about 350 ° C. and melted. The end of the preheated pleated body was pressed and sealed by adhesion. The other side of the pleated body was similarly sealed by welding the end plate to complete the filter cartridge. The end plate is manufactured by injection molding.
There were almost no visible bubbles in the end plate weld of the completed filter cartridge, and the filter passed the integrity test.

Comparative Example 1 A filter cartridge was completed in the same manner as in Example 2, except that the end plate was used without prior drying. Many visually confirmable air bubbles were observed in the end plate welding portion of the completed filter cartridge, and the completeness test was rejected.

[0030]

According to the production method of the present invention, a filter cartridge made of a polysulfone-based polymer as a raw material, having excellent chemical resistance and filtration stability, and producing no toxic gas or the like during incineration disposal treatment can be produced. Thus, it can be manufactured with high integrity without generating microbubbles on the end plate which is one of the components.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Perimeter cover 2 Membrane support 3 Microporous filtration membrane 4 Membrane support 5 Core 6a End plate 6b End plate 7 Gasket 8 Liquid outlet

Claims (2)

[Claims] 1. A microfiltration filter cartridge comprising a microporous filtration membrane, a membrane support, a core, an outer peripheral cover, and an end plate, wherein all of the above components are made of a polysulfone-based polymer. A method for producing a microfiltration filter cartridge, comprising subjecting an end plate to a drying treatment in advance and then subjecting the end plate to heat welding. 2. Component microporous filtration membrane, membrane support,
2. The core, the outer peripheral cover and the end plate are all made of polyethersulfone.
A method for producing the microfiltration filter cartridge according to the above.