JP2007050313A - Pleat type cartridge filter apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cartridge filter apparatus which has high filtering efficiency and long filter life span and which is manufactured inexpensively. <P>SOLUTION: In the cartridge filter apparatus having a pleated filter medium, a core, sleeves and two end caps (up and down cover part), the filter medium section which is orthogonal to the pleat is provided with a mountain fold line part, which does not reach the sleeves, at the core side and is provided with a valley fold line part, which is more proximal to the core side than the mountain fold line part, at the sleeve side. Thus, the buckling of the filter medium is prevented when the mountain fold line part and the valley fold line part are mutually overlapped via the pleat. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pleated cartridge filter device having high filtration efficiency and a long filter life. More specifically, the present invention relates to a pleated cartridge filter device that increases the filter area contributing to filtration and can be manufactured at low cost.

  Filters are used to separate foreign substances and particles in various fluids. They can capture the desired foreign substances and particles, are simple and easy to use, and have a high particle retention capacity (accommodating capacity). The function that is long is required. As such a filter, a pleat type in which a nonwoven fabric or a film sheet (membrane) is folded into a pleat shape is known. A pleated filter has an advantage in that a large filtration area can be produced.

  Applications of filters range from relatively simple ones such as vehicle oil and air filtration devices to precise ones such as wafer cleaning and photoresist filtration for manufacturing semiconductor devices, and filtration in the medical field. In particular, in the semiconductor field where precise filters are required, finer wiring widths have been demanded as the degree of integration of LSIs has improved in recent years, and there are technologies for eliminating extremely fine foreign matters in the manufacturing process for patterning LSIs. It is requested. Patterning is generally performed by applying a photoresist to a silicon wafer and utilizing the difference in solubility in the developer between the exposed and unexposed areas. However, foreign matter may enter the wafer or the resist solution. If this is the case, patterning to the line width as designed cannot be performed, causing a defect. For example, at present, even if foreign matter of about 0.05 μm remains in the filtered photoresist solution, it causes defects and wiring defects. However, since the photoresist solution usually has the property of easily generating gel due to stagnation and standing for a long time, the gel is generated in the photoresist solution before the photoresist solution is applied to the silicon wafer and exposed to light. (Here, the gel means a material different from a photosensitive material partially altered in the photoresist). When such a gel is present in the photoresist solution, undissolved foreign matters remain in the pattern to be dissolved in the developer solution by exposure to the photoresist film on the silicon wafer, resulting in pattern defects.

  Filter materials for removing ultrafine particles / foreign substances as described above are very expensive, and the amount of filter materials used should be saved as much as possible within a wide filtration area so that clogging is unlikely to occur during use. Is preferred. Here, the area of the part where the particles that do not pass through the filter are actually deposited is referred to as an effective filtration area.

  Usually, in order to increase the effective filtration area in order to prevent clogging and extend the usable period (life), the area of the filter material to be used is increased. However, normal pleat folds are composed of ridges with uniform height, so the filter must be tightly folded so that the sides of the pleat fold ridges are in contact with each other in order to increase the area of the filter material used. . FIG. 3 is a cross-sectional view of an example of a normal pleated fold filter, in which the fluid to be filtered is supplied from the upstream (or outside) of the drawing, and the filtrate flows downstream (or inside). In FIG. 3, the heights of the mountain fold line and the valley fold line are designed to be constant. In such a tightly folded filter, when a fluid containing foreign particles is filtered, particles that do not pass through the filter accumulate only on the upper part of the fold mountain, causing clogging, and the folded part functions effectively. (Effective filtration area becomes small), resulting in a problem that the filter life is shortened.

In addition, as a deformation of a normal pleat fold in an out-in-pass type pleated fold filter material, a mountain fold line at the top of a part of a mountain facing the sleeve is folded into a V shape to form an M shape. A configuration is also proposed in which the height of the top of the mountain is constant (for example, Patent Document 1). The filter material of Patent Document 1 is a space on the outer peripheral side that is inevitably generated when the inner peripheral side (core side) is dense and the outer peripheral side (sleeve side) is rough when a uniform pleat fold is applied to the cylindrical filter material. It is the structure for expanding the filter material area to be used effectively. Therefore, since the filter medium of Patent Document 1 has a structure in which the inner peripheral side and the outer peripheral side are dense, the filter is further tightly folded and the pleats are in close contact with each other, clogging is more likely to occur, and the filtration is increased. The area cannot work effectively and the effective filtration area is smaller.
Japanese Utility Model Publication No. 62-87710

  As described above, there has been a demand for a method for expanding the effective filtration area and saving the filter material area actually used, but the outer diameter dimensions such as the sleeve outer diameter and height of the filter device are compatible. Therefore, it was necessary to achieve these objects without changing the outer diameter.

  In the Japanese Patent Application No. 2004-120359 which is an unpublished prior application relating to the inventors' invention, the present inventor folds a square filter material into a pleat shape and is parallel to the pleat folding of the filter material. Filter medium 1 obtained by sealing both ends together into a substantially cylindrical shape, a filtrate side core (porous inner cylinder) 2, a supply liquid side sleeve (porous outer cylinder) 3, and two end caps (upper and lower lid portions) Filter device in which the filter medium 1 is inserted between the core 2 and the sleeve 3 and sandwiched between upper and lower end caps, and the upper and lower end edge portions of the filter medium are liquid-sealed and thermally welded to the end cap. In the cross section of the filter material orthogonal to the pleat fold, one fold line a, two valley fold lines b in contact with the core outer peripheral surface on both sides thereof, and two mountain fold lines c in contact with the sleeve inner peripheral surfaces on both sides thereof are shown. Exists A cartridge filter device is devised which includes a low ridge portion on the core side, two valley portions on the core side on both sides thereof, and a W-shaped portion formed with two high ridge portions on the sleeve side on both sides thereof. did. The device was found to be clogged, has a large effective filtration area, and has a long service life.

However, in this structure, unless the filter material and the supporting material (sheet) attached thereto are made to have high rigidity, when the valley portion of the filter medium is closely packed on the core side, the filling rate of the crest portion on the sleeve side is 25. It has been found that the effective filtration area decreases because the pleats constituting the peak portion buckle or bend.
Accordingly, it is an object of the present invention to provide a pleated cartridge filter device that can maintain an effective filtration area even when a conventional filter material or support that is conventionally used is used.

(1) The present invention relates to a filter medium formed into a cylindrical shape by folding a sheet-like (membrane-like) filter material into a pleat shape and sealing both end edges parallel to the pleat fold of the filter material. And an outer porous sleeve and two end caps, and the filter medium formed in the cylindrical shape is inserted into a space of a radial distance B between the core and the sleeve, and is sandwiched between the upper and lower end caps. In the cartridge filter device, wherein the upper and lower edge portions of the filter medium are heat-sealed in a liquid-tight manner to the end cap;
The filter medium is configured by folding the filter medium so as to have the following characteristics. That is, when the filter medium defines the ridges and valleys of the fold line as viewed from the sleeve side from the core side, (a) at least two core side fold lines that are in contact with the core and 1 between the core side valley fold lines provided therebetween. A core-side fold line unit including a core-side fold line that is less than the distance B and (b) at least two sleeve-side fold lines that are connected to the core-side pleat unit and are in contact with the sleeve. A sleeve-side pleat unit that includes a valley fold line that is less than the sleeve-side fold line and that does not reach the core, and (c) the height A of the core-side fold line in the core-side pleat unit Is formed at a position higher than the height C of the valley fold line of the sleeve side pleat unit, whereby the peak portion having the core side fold line and the valley portion having the sleeve side fold line partially overlap each other. And wherein the are.
The superposition here is not direct superposition but superposition where filter material pleats are interposed. Also, the broken line cannot be clearly specified due to the thickness of the filter medium (if the support material is used, the filter medium and the support medium), so the top of the broken line part outside the filter medium (bottom edge in valley folding, top edge in mountain folding) and Define.
(2) In a preferred embodiment, the number of mountain fold lines on the sleeve side is the same as or less than the number of valley fold lines on the core side.
(3) Preferably, a support material is used on at least one side of the filter material to provide a reinforcing effect and increase the flow path.
(4) Preferably, the total number of core side fold lines of the filter material relative to the outer diameter D ₁ (mm) of the core, the inner diameter D ₂ (mm) of the sleeve, and the total thickness t (mm) of the filter material and the support material n ₁ has a relationship of n ₁ = (πD ₁ /2t)×(1.1 to 1.9), and the total number n ₂ of mountain-fold lines on the sleeve side is n ₂ = (πD ₂ / 2t) × A relationship of (0.25 to 0.5) is given. This keeps the filling rate on the sleeve side low and increases the filtration capacity.
(5) The height A of the core side fold line is broadly 30 to 90%, preferably 40 to 80% of the radial distance from the core to the sleeve.

  The overlapped portion increases in density and is supported by the core side pleats as long as it is overlapped, so that the mechanical strength is greatly increased. Therefore, the overlapping ratio is not so important, but is, for example, 5 to 50%, preferably 5 to 40%, more preferably 5 to 30% of the distance B from the core to the sleeve.

The operation and effect of the present invention will be specifically described later with reference to examples, but the principle will be described here.
As described above, in Japanese Patent Application No. 2004-120359, a low mountain fold that does not reach the sleeve is formed on the core side, and the density of the filter material on the core side is increased to increase n ₁ = (πD ₁ / 2t) × (compression ratio). However, in this state, the sleeve side becomes too rough, so that the mountain on the sleeve side falls down and the intended purpose cannot be sufficiently achieved. Therefore, a valley fold is formed on the sleeve side as described above, and a mountain fold on the core side and a valley fold on the sleeve side are overlapped at an intermediate portion between the core and the sleeve. The closest packing number in units of 2t (that is, converted to the number of folding lines) where D is the diameter of the overlapped intermediate portion is (πD / 2t) × (compression rate), and there is no compression. Assuming (compression rate = 1), the filling rate at the diameter D (when the compression rate is 1 in common sense) is n = (πD / 2t), where n is the actual number of fillings. As will be discussed later, n is in the following relationship with respect to the number of core side valley folds n ₁ and the number of sleeve side mountain folds n ₂ from the simple consideration of FIGS.

In the case of FIG. 1 (Example 1), n ₁ : n ₂ : n = 2: 2: 3, in other words, n ₂ = n ₁ and n = (3/2) n ₁ .
In the case of FIG. 2 (Embodiment 2), n ₁ : n ₂ : n = 3: 2: 4, in other words, n ₂ = (2/3) n ₁ and n = (4/3) n ₁ .
In the case of Example 3, n ₁ : n ₂ : n = 5: 4: 7, in other words, n ₂ = (4/5) n ₁ and n = (7/5) n ₁ .
In Japanese Patent Application No. 2004-120359, n ₁ : n ₂ : n = 2: 1: 2, in other words, n ₂ = (1/2) n ₁ and n = n ₁ .
Assuming now that D ₂ = 2D ₁ and the overlapping portion is exactly at the center of D ₂ and D ₁ , that is, at the diameter D = (D ₁ + D ₂ ) /2=1.5D ₁ , the filling rate = n / (1 .5πD ₁ /2t)=n/1.5n ₁ .

In the example of FIG. 1, if n = (3/2) n ₁ is taken into consideration, the filling rate of the central part = 1 (= 100%), and sufficient support strength can be provided by overlapping the central part.
In the example of FIG. 2, if n ₂ = (4/3) n ₁ is taken into consideration, the filling rate becomes 0.89 (= 89%), and sufficient support strength can be provided by overlapping the central portion. By the way, in Japanese Patent Application No. 2004-120359, there is no overlapping portion and the filling rate at the center D is 0.67 (= 67%). However, since there is a large space on the sleeve side, this filling rate provides support strength. Insufficient due to shortage. The conventional ordinary pleated filter material also has n ₁ = n ₂ = n, and the filling rate is about 0.67 (= 67%) at the center.

From the above considerations, it is desirable that the filling rate in the vicinity of the center is 0.7 or more, preferably 0.8 or more, more preferably 0.9 or more, and about 1 at maximum.
When the overlapped portion is formed and mechanically strengthened in this way, the filter membrane is not bent or buckled, so that a large space can be secured above the overlapped portion, and the storage capacity of the filtration residue is increased.
Furthermore, since the packing density below the overlapped portion is at most about 100% multiplied by the compression rate, there is a margin for filtration and the filtrate can be discharged well.

  Since the filter of the pleated cartridge filter device of the present invention includes a low mountain fold portion on the core side, the filter area contributing to filtration is greatly increased as compared with the prior art. On the other hand, the upper part of the core side fold part is mechanically strengthened by overlapping the valley part on the sleeve side, and the pleat part on the sleeve side is strengthened, so that the large filter area can be maintained.

  According to conventional common sense, in order to increase the filter area, it is necessary to fill the filter device with a filter having the widest possible area, and it is necessary to increase the number of pleats in the outer peripheral portion. On the other hand, in the present invention, an unexpectedly narrow filter area (small filling amount) and a high filtration efficiency and a long filter life can be obtained, and a separate reinforcing means is used by providing a superposition part as described above. The filter medium can be prevented from buckling using the filter medium itself, so that a cartridge filter device having a much longer life than the conventional one can be provided by slightly changing the pleating process of the conventional pleated filter membrane. be able to.

  The pleated type cartridge filter device of the present invention includes a filter medium formed in a cylindrical shape by folding a sheet-like filter material into a pleat shape and sealing both end edges parallel to the pleat fold of the filter material, and an inner porous core And an outer porous sleeve and two end caps, and the upper and lower end edge portions of the filter medium are inserted between the upper and lower end caps by inserting the cylindrically formed filter medium between the core and the sleeve. In a liquid-tight heat-welded manner to the end cap. The filter medium used here has a characteristic structure in which the filter medium is pleated and folded according to the present invention.

  The filter material of the present invention may be of any material as long as it has a hole having a desired size depending on the size of the foreign matter to be removed in the processing solution. For example, when filtering a photoresist solution , Tetrafluoroethylene resin (hereinafter referred to as PTFE), polyethylene, polypropylene, SUS, nylon, polytetrafluoroethylene-perfluoroalkyl vinyl ether (hereinafter referred to as PFA) having fine pores of about 0.05 to 0.2 μm A filter film made of a material such as polyvinylidene fluoride (PVDF) is used, but is not limited thereto. In addition, when filtering chemicals used for manufacturing semiconductor devices, such as a rinsing liquid for silicon wafers, a filter film of the above-described material having fine pores of about 0.05 to 1.0 μm is used.

  In the case of a resin material, the thickness of the filter material is, for example, 0.1 to 2.0 mm. Even if the thickness is less than 0.5 mm, there is a filter material with low bending rigidity, and the use of a support material prevents the filter from buckling and pressure loss from increasing. Moreover, if it exceeds 2.0 mm, not only will the pleating process be very difficult, but the upper limit of the filter material area to be used will be limited, and as a result, the effective filtration area will decrease and the desired performance cannot be exhibited.

Example 1
FIG. 1 shows a first embodiment of the present invention, and shows a cross section perpendicular to a fold line of a filter medium 1 having a structure according to the present invention mounted between an outer surface of a core 2 and an inner surface of a sleeve 3. The definition of the height of the broken line in the radial direction is as described above.

The filter medium 1 is constructed by folding the filter medium 4 into the structure shown in the figure. When the valley of the pleat is determined by looking at the sleeve side from the core side, (a) two core side valley fold lines in contact with the core 2 a core side pleat unit (in this example, W-shaped) including a ₁ , a ₃ and a core side fold line a ₂ that is provided between them and does not reach the sleeve 3; and (b) the core side pleat unit. A sleeve-side pleat unit (in this example, M-shaped) including at least two sleeve-side fold lines b ₁ and b ₃ that are connected to each other and a sleeve-side valley fold line b ₂ that is provided between them and does not reach the core 2 To make. These units (a) and (b) repeat alternately. And (c) the height A of the core side fold line a _{2 in} the core side pleat unit is formed at a position higher than the height C of the valley fold line b _{2 in} the sleeve side pleat unit, whereby the core side fold line a ₂ The crest having the ridge and the trough having the sleeve side fold line b ₂ partially overlap each other (a portion between A and C) with a pleat interposed therebetween. As a result, the pleat unit (b) on the sleeve side is supported by the pleat unit (a) on the core side, and is supported by an increase in filling density due to overlap in the range between A and C, thereby preventing buckling. In this way, a sufficient space for the filtration residue (solid particles) (see 5 in FIG. 3 and omitted in the examples) is sufficiently secured above the core-side mountain fold a ₂ .

Example 2
FIG. 2 shows another embodiment. In this example, (a) a core side including three core side fold lines a ₁ , a ₃ , a ₅ in contact with the core 2 and core side fold lines a ₂ , a ₄ provided between them and not reaching the sleeve 3 A pleat unit; and (b) at least two sleeve side mountain fold lines b ₁ and b ₃ that are connected to the core side pleat unit and contact the sleeve 3, and a sleeve side valley fold line b ₂ that is provided between them and does not reach the core ₂ And a sleeve side pleat unit (in this example, M-shaped). These units (a) and (b) repeat alternately. And (c) the height A of the core side fold line a _{2 in} the core side pleat unit is formed at a position higher than the height C of the valley fold line b _{2 in} the sleeve side pleat unit, whereby the core side fold line a ₂ , The peak portion having a ₄ and the valley portion having a sleeve side valley fold line b ₂ partially overlap each other (portion between A and C) with a pleat interposed therebetween. As a result, the sleeve-side pleat unit (b) is supported by the core-side pleat unit (a) and by increasing the packing density due to the overlap between A and C, thereby preventing buckling. In this example, the space for the filtration residue (solid content) is larger than in Example 1.

  In general, the pleat folding structure of the filter medium 1 includes: (a) at least two core side fold lines that are in contact with the core, and one core side fold line that is provided between them and that is less than the core side valley fold line and does not reach the sleeve inner diameter. And (b) at least two sleeve-side fold lines connected to the sleeve, connected to the core-side pleat unit, and one less than the sleeve-side fold line provided therebetween, and A sleeve-side pleat unit including a valley fold line that does not reach the core outer diameter, and (c) a height of a core-side fold line in the core-side pleat unit is higher than a height of a valley fold line in the sleeve-side pleat unit. So that the crest having the core side fold line and the trough having the sleeve side fold line may partially overlap each other with pleats interposed therebetween.

  As described above, when the particle-containing fluid is filtered by the filter having the configuration of the present invention, the folded filter portion also functions effectively to perform filtration, and the filtered particles have a large space above the core side fold line. Since it can be deposited inside, the time until the filter becomes clogged and becomes difficult to use (filter life) becomes longer. On the other hand, the outer strength with low pleat density on the sleeve side is reinforced by the overlap of the peak part including the core side folding line and the valley part including the sleeve side folding line, thereby preventing the filter material from buckling and remaining. It becomes possible to maintain a large retention capacity for the particles.

Example 3
As shown in FIG. 6, as an intermediate form between the first embodiment and the second embodiment, the core side may be changed so that one mountain fold line a ₂ and two mountain fold lines a ₄ and a ₆ mountain fold appear alternately. The core side fold lines are represented by a ₁ , a _3, a ₅ , a ₇ , and a ₉ , and the sleeve fold lines are represented by b ₁ , b ₃ , b ₅ , and b ₇ , respectively.

  As described above, the filter of the present invention can ensure high rigidity (shape retention) so as not to buckle when the end caps are fused by increasing the density of pleat folding. Since the filtration efficiency is high, it is possible to use a support material to ensure easy folding and high rigidity (shape retention), while reducing the density of pleat folding to save the amount of filter material used.

As described above, in Japanese Patent Application No. 2004-120359, which is an unpublished prior application of the present inventor, a filter medium provided with only a mountain fold portion (W shape) having a low mountain fold line on the core side is provided ( FIG. 4). At that time, in order to reinforce the filter material on the sleeve side, the total thickness t (mm) of the filter material and the support material is set (the thickness of one peak or valley is 2t), and the outer diameter D _{1 of the} core to be used. It has been proposed to have a relationship of n = (πD ₁ /2t)×(1.1 to 1.9) between (mm) and the total number n of the valley fold lines of the filter material. This was intended to provide a mechanical reinforcing effect by compressing the density on the core side to (1.1 to 1.9) times the packing density of the closest packing material without compression.

  However, in the structure of the above-mentioned prior application, the filter material packing density on the sleeve side becomes extremely small, so if the filter medium is not inserted between the core and the sleeve, the buckling of the filter medium cannot be avoided and used. There is a problem that the filtration capacity (that is, the service life) is reduced due to buckling or bending.

For example, the number of valley fold lines in contact with the core side is n ₁ = (πD ₁ / 2t) from the above formula when the core side is packed without compression, but the mountain fold line in contact with the sleeve inner diameter D ₂ The number required for fine packing without compression is (πD ₂ / 2t). If the number of fold lines on the sleeve side is actually n ₂ , the filter material filling rate on the sleeve side is n ₂ / (πD ₂ / 2t). Therefore, for example, assuming that D ₂ = 2D ₁ , in the above-mentioned prior application, n ₂ = 0.5n ₁ , so the filling rate on the sleeve side is 0.5 (πD ₁ / 2t) / (π2D ₁ / 2t) = It is 0.25 (25%), and it can be seen that there is a possibility that a large buckling may occur as compared with a conventional filling rate of 0.5 (50%).

In Example 1 of the present invention, since n ₂ = n ₁ , the filling rate on the sleeve side is 0.5 (50%). However, the normal folding is possible in that a large space can be secured above the low mountain fold line on the core side. Longer life can be expected than the other, and the problem of buckling is eliminated by superposition of the core side mountain fold and sleeve side valley fold. When the intermediate diameter D = 1.5D ₁ is assumed in the above explanation of the principle, the filling rate at the diameter D is about 100% (if there is compression at the location of the core diameter D ₁ , this is multiplied by the compression rate). It can be seen that a sufficiently high support strength is provided as compared with the case of the filling rate of about 67% in the above-mentioned prior application example in which the sleeve side valley fold is not used.

In Example 2 of the present invention, n ₂ = (2/3) n ₁ and the filling rate on the sleeve side is only 0.33 (= 33%), so it is large above the two low mountain fold lines on the core side. Longer life than normal folding can be expected in that space can be secured. On the other hand, the problem of buckling is solved by overlapping the core side mountain fold and sleeve side valley fold. As already described, the filling rate at the diameter D is about 89%, and it can be seen that a sufficiently high support strength is provided as compared with the above-mentioned prior application example in which the sleeve side valley fold is not used.

Similarly, in Example 3, since n ₂ = (4/5) n ₁ , the filling rate is 0.4 (40%), and the same effect can be obtained. Further, since n = (7/5) n ₁ , the filling rate at the diameter D is n / 1.5n ₁ = 0.93, that is, about 93%, which is compared with the above-mentioned prior application example that does not use the sleeve side valley fold. It can be seen that a sufficiently large support strength is provided.
The above is slightly modified in consideration of the compression ratio on the core side.
From the above, generally, the filling rate on the sleeve side may be set to 0.25 to 0.5.
The filling rate of the overlapping portion is preferably set in the range of 0.7 to 1 (about 70 to 100%).

In the filter medium of the present invention, a support material may be used on at least one surface or both surfaces of the filter material. For example, after a pair of support materials are attached to both surfaces of the filter material, the filter material is folded into a pleat shape and both side edges are sealed. It may be worn. As the support material, commonly used materials such as mesh and nonwoven fabric can be used. By using the support material, it is possible to increase the bending rigidity of the entire filter and improve the shape retention.
The support material is used in the form of a net, porous sheet, or non-woven fabric. For example, PFA, PTFE, tetrafluoroethylene-ethylene copolymer (hereinafter referred to as ETFE), PVDF and other thermoplastic fluororesins, polyethylene, polypropylene A material such as SUS is preferably used.

A substantially cylindrical filter medium obtained by folding a square filter material of the present invention into a pleat shape and sealing both ends parallel to the pleat fold of the filter material is inserted between a core and a sleeve, Further, the upper and lower end edge portions of the filter medium are liquid-tightly heat-sealed to the end cap, and are stored in the cartridge filter device.
The cartridge filter device of the present invention can be used in an out-in-pass method. When the fluid passes through the pleated filter, the high folds surrounding the low folds with respect to the fluid supply direction become openings and particles and / or foreign matters contained in the fluid are effectively captured, and the filter The exposed surface can be fully utilized.
In the case of resin-based materials, there are many types of support materials on the fluid supply side (primary side) by selecting various combinations of support materials that can maintain the pleat mountain shape (high or low) during or after pleating. Exists.
Further, either a liquid or a gas can be used as the fluid.

Prototype example according to Example 1 PFA double woven net (fiber diameter 0.22 mm) as the primary (fluid supply side) support material, and 100 μm thick polytetrafluoroethylene (manufactured by zytex) as the prefilter , PTFE) non-woven fabric, a material of PFA thick net (fiber diameter 0.11 mm) as a secondary side (fluid discharge side) support material, and a PTFE membrane filter having a membrane area of about 7800 cm ² and a nominal pore size of 0.1 μm In this order, according to Example 1, the height A of the core side fold line a ₂ = 12 mm / the height C of the sleeve side fold line b ₂ = 10 mm / the height B of the sleeve side fold lines b ₁ and b ₃ = The repeating unit composed of 15 mm is repeatedly pleated to obtain a core side valley fold number n ₁ = 114 and a sleeve side mountain fold number n ₂ = 114, and then both side edges A filter medium (sleeve inner diameter 76 mm, core outer diameter 46 mm) was assembled by sealing and using as a filter medium.

For comparison, a prototype of n ₁ = n ₂ = 114 was produced in the prototype example of Example 1 by conventional ordinary pleat folding. The membrane area was about 6500 cm ² .

Filter performance evaluation The supply water containing dust (median diameter of bentonite 5 μm) at a concentration of 10 ppm is supplied to the cartridge filter device using the filter media of Example 1 and Comparative Example at a constant flow rate of 5 L / min at room temperature. FIG. 5 shows the result of plotting the relationship between the flow, time and the differential pressure (supply pressure-discharge pressure differential pressure). From the figure, the life (the filtration volume until the supply pressure minus the discharge differential pressure reaches 1 kgf / cm ² ) is 5 L / min × about 200 minutes = about 1000 L in Example 1, and in the case of the comparative example (conventional example) 5L / min × about 100 minutes = about 500L.

  Example 1 has practical particle removal performance and a large outflow rate with respect to supply pressure, and the pleated type cartridge filter device of Example 1 has a life approximately twice that of a conventional normal pleated type filter device. The life of the filter medium was 1.2 times longer.

It is the cross-sectional schematic which shows the structure and use condition of the filter material part of the cartridge filter apparatus by Example 1 of this invention. It is the cross-sectional schematic which shows the structure and use condition of the filter material part of the cartridge filter apparatus by Example 2 of this invention. It is the cross-sectional schematic which shows the structure and use condition of the filter material part of the conventional cartridge filter apparatus. It is the cross-sectional schematic which shows the structure and use condition of the filter material part of the unpublished cartridge filter apparatus which this inventor developed and used as the object of the prior application. It is a graph which shows the change of the pressure with respect to the filtration time of the filter apparatus at the time of making flow volume constant. It is the cross-sectional schematic which shows the structure and use condition of the filter material part of the cartridge filter apparatus by Example 3 of this invention.

Explanation of symbols

1 Filter medium 2 Core 3 Sleeve 4 Filter material a ₁ , a _3, a ₅ , a ₇ , a ₉ Core side trough fold line a ₂ , a ₄ , a ₆ Core side fold line b ₁ , b ₃ , b ₅ , b ₇ sleeve side mountain fold line b _2, b ₄ sleeve side inward fold line

Claims (7)

A filter material formed into a cylindrical shape by folding a sheet-like filter material into a pleat shape and sealing both end edges parallel to the pleat fold of the filter material, an inner porous core, an outer porous sleeve, and two end caps And inserted the filter medium formed in a cylindrical shape between the core and the sleeve and sandwiched between the upper and lower end caps, and the upper and lower end edge portions of the filter medium were liquid-sealed and thermally welded to the end caps, In the cartridge filter device;
When the pleats are defined by looking at the sleeve side from the core side of the filter medium, (a) at least two core side fold lines in contact with the core and one core side fold line provided therebetween A core side pleat unit including a core side fold line which is as small as possible and does not reach the sleeve inner diameter; and (b) at least two sleeve side fold lines connected to the core side pleat unit and in contact with the sleeve. A sleeve-side pleat unit including a valley fold line that is one less than the sleeve-side fold line and does not reach the outer diameter of the core, and (c) the height of the core-side fold line in the core-side pleat unit is the sleeve It is formed at a position higher than the height of the valley fold line of the side pleat unit, whereby the peak part having the core side fold line and the valley part having the sleeve side fold line are interposed through the pleats. Cartridge filter device characterized in that it partially overlaps are.   The cartridge filter device according to claim 1, wherein the number of mountain fold lines on the sleeve side is equal to or less than the number of valley fold lines on the core side.   3. The cartridge filter device according to claim 1, wherein a support material is used on at least one side of the filter material. The total number n ₁ of the core side fold lines of the filter material with respect to the outer diameter D ₁ (mm) of the core, the inner diameter D ₂ (mm) of the sleeve, and the total thickness t (mm) of the filter material and the support material is n ₁ = (ΠD ₁ /2t)×(1.1 to 1.9), and the total number n ₂ of fold lines on the sleeve side is n ₂ = (πD ₂ /2t)×(0.25 to 0) 5) The cartridge filter device according to claim 3.   2. The cartridge filter device according to claim 1, wherein a height A of the core side fold line is 30 to 90% of a radial distance B from the core to the sleeve.   The crest having the core side fold line and the trough having the sleeve side fold line are overlapped within 5 to 50% of the radial distance B from the core to the sleeve via a pleat. Item 2. The cartridge filter device according to Item 1.   The cartridge filter device according to claim 1, wherein a filling rate of the pleats in the overlapping portion is from 0.7 to 1.

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