WO2006106937A1

WO2006106937A1 - Filter membrane and method of manufacturing the same

Info

Publication number: WO2006106937A1
Application number: PCT/JP2006/306869
Authority: WO
Inventors: Akira Sato; Fumio Nozaki; Hirokazu Kuwabara
Original assignee: Entegris, Inc.
Priority date: 2005-04-01
Filing date: 2006-03-31
Publication date: 2006-10-12
Also published as: JP2006281124A; TW200702043A

Abstract

A filter membrane capable of preventing the crests of pleats adjacent to each other from being fitted to each other at advantageous cost without using a separate member, enabling an increase in rigidity and strength in a direction along the pleat lines of the pleats, and capable of increasing backwashing effect. The filter membrane (1) formed in a pleat shape comprises folded and piled parts (10a) and (10b) extending along a direction orthogonal to the folding lines (2a) and (2b) of the pleats. The folded and piled parts (10a) and (10b) are formed by folding back the filter membrane (1) through first pleat lines (11) and (11') and second pleat lines (12) and (12'). The filter membrane (1) in three portions is formed of inner portions (1a) and (1a'), outer portions (1b) and (1b'), and intermediate portions (1c) and (1c') between the first and second pleat lines (11) and (11') and (12) and (12'). In the cylindrical filter membrane (1), the folded and piled parts (10a) and (10b) are formed near the intermediate parts between the vertical center part and the upper and lower ends thereof, and the outer pockets (13) and (13') thereof are opened to the upper and lower end sides.

Description

Specification

Filter membrane body and manufacturing method thereof

Technical field

TECHNICAL FIELD [0001] The present invention relates to a filter membrane body and a method for manufacturing the same, and in particular, a porous filter made of resin that is continuously pleated (folded) and used for fluid filtration and purification treatment. The present invention relates to a film body and a method of manufacturing the film body.

Background art

[0002] A filter membrane body (a filter membrane itself or a laminate of a nonwoven fabric or the like on a filter membrane) that is continuously pleated to increase the contact area with a fluid to be filtered is well known. It has been. In a filter membrane body with a large number of pleat folds, when adjacent pleats are in close contact with each other or immediately contact each other, the flow of fluid into the pleats is reduced and the effective filtration area is reduced. Technical capabilities for preventing this are disclosed in, for example, JP-A-5-329314 and JP-A-8-215527. In these documents, a tape-shaped member (separator Z separator material) made of thermoplastic resin is pasted on the filter membrane surface so as to be orthogonal to the pleat crease, so that the adjacent pleat mountain Try to keep an interval.

However, when a tape-like member separate from the filter film body as described above is used, there is a problem that not only the manufacturing cost of the film body increases, but also the manufacturing process becomes complicated.

[0004] As disclosed in JP-A-5-64728, etc., the filter membrane body with pleats is formed into a cylindrical shape so that a large number of pleats are continuous in the circumferential direction. Incorporated into the element), it is generally used for purification / purification of chemicals, etc. during the manufacture of semiconductor elements, flat panel displays, etc.! RU The structure and assembly process of the filter assembly are as follows.

[0005] First, a support such as a nonwoven fabric is laminated on one side or both sides of a filter membrane made of wholly fluorine resin or the like to obtain a filter membrane body. This is because the filter membrane alone is very loose and does not have a pleated crease, so that the workability and handling properties are poor, and thus the membrane is reinforced with the support. This filter membrane body (pleated in the left and right direction) The pleats are processed so as to continue, and this is cut into a predetermined length in the left-right direction (the number of pleats), and the left and right ends of each filter membrane are joined to form an endless cylindrical shape. Next, after this cylindrical filter film body is housed between a core which is an inner porous cylinder and a sleeve which is an outer porous cylinder, end caps are liquid-tight (or air-tight) at the upper and lower ends of the cylindrical shape. The assembly (filter element) is formed by fusing.

[0006] The filter assembly is accommodated in the housing at the time of use, and the fluid to be filtered is introduced into the introduction port force housing as shown in Fig. 1 of the above Japanese Patent Publication No. 5-64728, and then the cylindrical filter. The membrane is filtered through the radially outer center and then discharged from the end cap outlet to the outside of the housing.

[0007] In addition to the above-described problems when the tape-shaped member is attached to the film surface, the cylindrical filter film has the following problems.

[0008] (ii) Although the filter membrane body is generally reinforced by laminating a non-woven fabric or the like as described above, when the pleats that are still low in rigidity and strength continue in the left-right direction, the membrane body is It tends to buckle in the direction (the direction along the pleat crease). For this reason, for example, when the end cap is fused to the above-described cylindrical filter membrane body, a sufficient force in the vertical direction (axial direction) cannot be applied to the membrane body. Therefore, simple assembly such as pressing the end cap against the upper end of the membrane body is possible. The means cannot be adopted. Furthermore, in order to increase the vertical strength of the film body, the number of pleats in the circumferential direction has been increased more than necessary. However, in this case, the distance between adjacent pleat ridges (outside in the radial direction) of the cylindrical membrane becomes too narrow, and the filtration function is reduced. In addition, since the pleats on the valley side (inner side in the radial direction) are denser than the peak side, during backwashing in which the cleaning liquid flows in the direction opposite to the fluid flow direction during normal operation (here, radially outward from the center) There is also a problem that the pleats are not displaced so much that the backwashing effect is not improved.

[0009] (Mouth) When using the filter assembly, when the fluid passes through the cylindrical filter membrane body from the radially outer side to the central portion, ideally, two filter membranes forming the peak side of each pleat It is desirable that the fluid pass so that the fluid pressure acts uniformly on the body surface to narrow the apex angle. In practice, however, the fluid pressure causes one or more pleat crests to collapse or be biased, causing fluid flow to concentrate on the collapsed crest or adjacent to the crest. The flow rate is unbalanced between the pleated valleys on both sides in contact. For this reason, there are cases in which the density and variation of the filtering function on the surface of the filter membrane body are more than expected, or the filtering ability is not fully exhibited.

[0010] (c) Conventionally, in order to improve the membrane surface cleaning effect by backwashing, the flow rate of backwashing solution can only be increased. However, if the flow rate is increased too much, the filter membrane body bursts or the membrane Due to the tensile stress applied to the body, the upper and lower ends of the film body and the end cap may be uncoupled, or even if this is not unraveled, the sealing performance of the joint may be lost. Therefore, there is a limit to increasing the flow rate of the backwashing liquid, and the flow direction of the backwashing liquid is monotonous, so there is a problem that the cleaning effect cannot be improved easily! / And! //.

Patent Document 1: Japanese Patent Laid-Open No. 5-64728

Patent Document 2: JP-A-5-329314

Patent Document 3: JP-A-8-215527

Disclosure of the invention

Problems to be solved by the invention

The present invention has been made paying attention to the above points, and an object of the present invention is to provide a filter film body capable of preventing the close contact between adjacent pleat mountains in a cost-effective manner using separate members. And a manufacturing method thereof.

[0012] Another object of the present invention is to increase the rigidity and strength in the direction along the pleat crease, to reduce deformation such as crushing of the pleat mountain top during use, and to enhance the backwash effect. It is providing the filter membrane body which can be manufactured, and its manufacturing method.

Means for solving the problem

[0013] According to the present invention, in order to solve the above-described problem, in the filter film body that is subjected to pleating processing in which mountain creases and valley creases (both folds are also referred to as pleat creases) are alternately provided, A fold portion extending along the crossing direction intersecting the mountain fold and the valley fold is provided, and the fold portion folds the filter film body from the first fold and the second fold extending along the crossing direction, respectively. A filter film body is provided between the first and second folds, wherein the filter film body is tripled from an inner portion, an outer portion, and an intermediate portion between the inner and outer portions. In the present invention, the “filter membrane body” refers to the filter membrane itself or a laminate of a support such as a nonwoven fabric on one side or both sides of the filter membrane. Examples of the material of the filter membrane include non-thermoplastic resins such as tetrafluorinated styrene resin, vinylidene fluoride resin, tetrafluoroethylene perfluoroalkyl butyl ether copolymer (PFA). ), Polypropylene, polyethylene, polysulfone, polyamide, polycarbonate, polyethersulfone, polyetherketone, copolymers thereof, thermoplastic resins such as polymer alloys, and the like, particularly polytetrafluoroethylene ( PTFE) and the like are suitable.

[0015] Examples of the support include tetrafluoroethylene / perfluoroalkyl butyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and ethylene tetrafluoride. Thermoplastic fluorine resin such as perfluoroalkyl butyl ether copolymer, hexafluoropropylene copolymer (EPE), tetrafluorinated styrene resin, nonwoven fabric such as polypropylene and polyethylene, net, porous sheet, etc. In particular, PFA, PTF E and the like are preferable.

[0016] The width of the folded portion (interval between the first fold and the second fold) is not particularly limited as long as it is equal to or larger than the minimum width that allows machining of the folded portion. It is desirable not to become too large.

[0017] The "intersection direction" includes not only the case where the fold-fold extension direction is perpendicular to the pleat fold line at 90 degrees, but also a case where the pleat fold line intersects obliquely.

In the present invention, the filter film body can be provided with one or a plurality of folded portions where the film body is partially tripled along the direction intersecting the pleat fold. This fold has a spacer function that maintains the pleat spacing almost evenly, and a shape maintenance function that maintains the cross-sectional shape of the pleats. When the interval is narrowed, it acts to resist this and widen the interval. In addition, the folded part reinforces the strength and rigidity of the film body in the direction along the pleat crease (up and down when the pleat is continuous in the left-right direction), and reduces the buckling of the film body in that direction. It can be done.

In the present invention, the filter membrane body can be a cylindrical filter membrane body incorporated in a cylindrical filter assembly. In this case, the inner portion of the folded portion The minute portion and the middle portion form an outer pocket that communicates with the outer space of the filter membrane body therebetween, and the outer portion and the middle portion form an inner pocket that communicates with the inner space of the filter membrane body therebetween. The outer pocket is closed by the flow of fluid from the outer space to the inner space passing through the inner space, and the inner pocket is opened by the flow of fluid from the inner space to the outer space. Folded parts can be set and arranged. As a result, the outer pocket of the folded portion does not open depending on the flow of the fluid that passes through the filter membrane body from the radially outer side to the inner center during the normal filtration process, so that a large amount of fluid flows into the outer pocket. do not do. On the other hand, depending on the backwash flow that passes through the filter membrane body outside the inner force in the direction opposite to the above flow, the inner pocket of the folded portion opens, and the fluid easily flows into the inner pocket. Therefore, at the time of backwashing, the folded portion is opened, and a flow parallel to the film surface can be generated through the folded portion, thereby enhancing the effect of removing the deposit on the film surface. In addition, since the folded portion is opened, it is possible to absorb the tensile stress applied to the backflushing membrane to some extent, so that the joint between the upper and lower ends of the membrane and the end cap is not damaged. The flow rate can be increased.

[0020] Note that when the flow during the normal filtration step is the radially inner force outside and the backwash flow is from the outside to the inside, contrary to the above aspect, the inner portion and the intermediate portion of the folded portion However, an outer pocket that communicates with the outer space of the filter membrane body is formed between them, and an outer portion and an intermediate portion form an inner pocket that communicates with the inner space of the filter membrane body therebetween, and passes through the filter membrane body. The inner pocket is closed by the flow of fluid from the inner space to the outer space, and the outer pocket is opened by the flow of fluid from the outer space to the inner space.

[0021] According to the present invention, there is also provided a method of manufacturing a filter film body that is subjected to pleating processing in which mountain folds and valley folds are alternately continued, and includes a mountain fold and a valley fold that are attached after the pleating. One or a plurality of folds extending along the intersecting direction intersecting with the first fold line and the second fold force extending along the intersecting direction, respectively. Folding, the filter membrane body is tripled from the inner part, the outer part, and the intermediate part between these inner and outer parts between the first and second folds. A method for producing a characteristic filter membrane body is provided.

In the method according to the present invention, in order to obtain the filter film body according to the present invention described above, first, the folded portion processing step is performed, and then the pleating force is performed (almost simultaneously). Including the case of processing folds and pleat folds;). The folded portion, for example, generates a substantially S-shaped (or Z-shaped) cross section on the film surface in the middle of sending the film body in which the film and the support body are laminated to the downstream of the process. It is created by folding the distorted portion in the vertical direction at the downstream position of and pressing and heating.

The invention's effect

[0023] In the present invention, by providing a folded portion on the filter film body to be pleated, adhesion between adjacent pleat mountains without using a member other than the filter film body such as a tape member is prevented. Compared with the case where a tape member or the like is used, the manufacturing cost of the filter membrane body is low, and the manufacturing process is simple.

[0024] In the present invention, the folding portion increases the rigidity and strength of the filter film body in the direction along the pleat fold, and the film body buckles in this direction. This enhances the handling of the membrane during assembly assembly, such as connecting the end cap to the upper and lower ends of the cylindrical membrane.

, Make it possible to use simple methods and means that could not be used in the past. In addition, the pleat shape of the cylindrical membrane can be maintained, and the pleat spacing between the pleats can be maintained, thereby enhancing the filtration effect. In addition, the flow direction of the backwash liquid during backwashing is partially changed to enhance the effect of removing foreign matter, and the folded portion is opened during backwashing to absorb the fluid pressure, so that the tensile stress applied to the film body is reduced. It can be relaxed and the joint with the end cap will not be damaged, and the backwash flow rate can be increased.

Brief Description of Drawings

FIG. 1 is a perspective explanatory view of a filter film body according to the present invention.

FIG. 2 is a cross-sectional explanatory view of an upper folded portion.

FIG. 3 is a cross-sectional explanatory view of a lower folded portion.

FIG. 4 is a cross-sectional explanatory view showing a pleated mountain adjacent to each other in a folded portion.

FIG. 5 is a perspective explanatory view showing a partially cutaway cylindrical filter membrane body.

FIG. 6 is a cross-sectional explanatory view of the filter membrane body in the normal filtration step along the line BB in FIG. FIG. 7 is a cross-sectional explanatory view similar to FIG. 6, showing the filter membrane during backwashing.

FIG. 8 is a schematic explanatory diagram of a folding part processing mechanism.

FIG. 9 is an explanatory view showing a cross section of a film body distorted in a substantially S shape by two bars.

FIG. 10 is an explanatory view showing a filter film body having a single oblique folded portion.

Explanation of symbols

[0026] 1, 1 'filter membrane

2a, 2b Pleated crease (mountain crease, valley crease)

10, 10a, 10b, 10 ', 10c Folded part

11, 11 '1st crease

12, 12 '2nd crease

la, la 'inner part

lb, lb 'outer part

lc, lc 'middle part

13, 13 'outer pocket

14, 14, inside pocket

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a filter membrane body 1 according to an embodiment of the present invention. Filter membrane body 1 consists of a porous support membrane (nonwoven fabric) (thickness 15; ζ) made of thermoplastic fluorine resin on both sides of a porous filter membrane (thickness 25 μm) made of tetrafluorinated styrene resin. ΐη Χ 2) is laminated. In the filter film body 1, the pleat folds (mountain crease 2 a and valley crease 2 b) extending in the up-down direction are continuous in the left-right direction after pleating. Further, the filter film body 1 is provided with folded portions 10 (10a, 10b) extending in the left-right direction in the vicinity between the center in the vertical direction and the upper end and the lower end, respectively. The height of the film body 1 is about 250 mm, the vertical widths of the folded portions 10a and 10b are about 10 mm, respectively, and the extending direction of the folded portions is 90 degrees with respect to the pleat crease.

2 and 3 are schematic cross-sectional views of the upper and lower folded portions 10a and 10b of FIG. 1, and the front side of FIG. 1 is on the left side of FIGS. The folded portion 10a is directed downward from the upper end. The filter film body 1 is folded upward at the first fold line 11 and then folded again downward at the second fold line 12. Thereby, in the folded portion 10a, the filter film body 1 is tripled from the inner side portion la, the outer side portion lb, and the intermediate portion lc between these inner and outer portions. Further, the inner portion la and the intermediate portion lc form an outer pocket 13 communicating with the outer space of the filter membrane body 1 therebetween, and the outer portion lb and the intermediate portion lc are interposed between the inner portion of the filter membrane body 1. Form an inner pocket 14 that communicates with the space. The outer pocket 13 and the inner pocket 14 are almost closed in FIG. 2.The outer pocket 13 can be opened upward with respect to the outer space, and the inner pocket 14 can be opened downward with respect to the inner space. .

[0030] The folding portion 10b is formed by folding the filter film body 1 downward at the first fold line 11 'and then folding it upward again at the second fold line 12'. Accordingly, in the folded portion 10b, the filter film body 1 is tripled from the inner portion la ′, the outer portion lb ′, and the intermediate portion lc ′. The film body 1 extends upward from the outer portion lb ′ and reaches the outer portion lb of the upper folded portion 1 Oa. In the downward folded portion 10b, the inner portion la 'and the intermediate portion lc' form an outer pocket 13 'communicating with the outer space of the filter membrane body 1 therebetween, and the outer portion lb' and the intermediate portion lc ' In the meantime, an inner pocket 14 ′ communicating with the inner space of the filter membrane body 1 is formed. The outer pocket 13 ′ and the inner pocket 14 ′ are almost closed in FIG. 3, but the outer pocket 13 ′ can be opened downward with respect to the outer space, and the inner pocket 14 ′ is opened upward with respect to the inner space. Is possible. Accordingly, in the upper and lower folded portions 10a and 10b, the openings (opening openings) of the outer pockets 13, 13 'face the upper and lower ends of the film body 1, and the openings of the inner pockets 14, 14' are the vertical direction of the film body 1. Turn to the center.

FIG. 4 is a schematic cross-sectional view showing adjacent pleat peaks in the folded portion 10 of the filter film body 1. In the filter film body 1, when the pleat peaks are made closer to the direction of the arrow A in order to increase the pleat density, the angle of the mountain folds 2a, 2a and the valley fold 2b is narrowed. It acts to widen the angle by resisting the narrowing of the angle. Therefore, in the filter film body 1, adjacent pleat mountains are not in close contact with each other and the filtration function is not deteriorated.

FIG. 5 is a perspective explanatory view showing the state in which the filter membrane body 1 of FIG. 1 is cut to a predetermined length in the left-right direction and arranged around the core 20 which is an inner porous cylinder, partially broken. Yes, filter element The outer sleeve, the upper and lower end caps, etc. are omitted. The filter membrane body 1 is on the front side of FIG. 1, that is, on the side where the outer portions lb and lb ′ face the outer sleeve (not shown) (hereinafter simply referred to as the outer side or the radial outer side), and the folded portion 10a. The inner portions la and la ′ of 10b are arranged on the side facing the core 20 (hereinafter simply referred to as the inner side or the radially inner side).

FIG. 6 is a cross-sectional explanatory view taken along the line B-B of FIG. 5, in which the outer pockets 13, 1 3 ′ of the folded portions 10a, 10b come to the outside, and the opening of the upper pocket 13 faces upward, The opening of the lower pocket 13 'faces downward. In this state, when the liquid to be filtered passes from the radially outer side to the inner central part, the fluid pressure pushes the outer portions lb and lb ′ of the folded portions 10a and 10b inward to close the outer pockets 13 and 13 ′. (The middle parts lc and lc 'are brought into contact with the inner parts la and la'). Therefore, the fluid hardly flows into the outer pockets 13 and 13 ', and the flow direction of the fluid is the same as that of the conventional cylindrical filter membrane without the folded portion, and the filtration capacity is not changed.

[0034] On the other hand, when the backwash liquid is allowed to flow from the inside to the outside during backwashing, the backwash liquid flows into the inner pocket as shown in FIG. 14, 14 ′ and works to open the pockets 14, 14 ′ (expanding the space between the outer part lb, lb ′ and the intermediate part lc, lc ′, thereby opening the inner pockets 13, 13 ′. ) ₀ Some of the liquid that has passed through the inner pockets 14 and 14 'has an effect of changing the flow between the inside and the outside, such as flowing upward and downward substantially parallel to the membrane surface. Thereby, peeling of the organic foreign matter adhering to the film surface is promoted. In addition, by opening the folded portions 10a and 10b during backwashing as described above, the tensile stress received by the film body 1 is absorbed * relaxed, so the backwash flow rate can be increased compared to the conventional case. This also increases the backwashing effect.

[0035] In the filter film body 1 described above, since the rigidity and strength of the film body 1 in the vertical direction are increased by the folded portions 10a and 10b, the joining process of the end cap to the film body 1 when the filter assembly is assembled can be simplified. Or the number of pleats in the cylindrical filter membrane body 1 need not be increased more than necessary, and the optimum number of pleats that maximizes the filtration effect can be achieved. Further, the folded portions 10a and 10b function to maintain the pleated chevron shape of the cylindrical filter membrane body 1 and to keep the pleat pleat interval substantially constant. Overefficiency is increased.

[0036] The processing of the folded portion 10 of the filter membrane 1 described above is performed by laminating the membrane and the nonwoven fabric supplied from the membrane supply roll and the nonwoven fabric supply roll (not shown), respectively. After that, it is performed before it is applied to a further downstream pleater (not shown). FIG. 8 is a schematic explanatory diagram of the folding portion machining mechanism. The mechanism is for forming one folded portion 10 ′ on the filter membrane 1 ′. The membrane surface of the filter membrane 1 ′ moving toward the downstream is crossed by two bars 31 and 32. Generates an upward / downward distortion that is almost S-shaped (or Z-shaped) (see Fig. 9), and the curved part is folded in the vertical direction at the processing part 33 immediately downstream and heated while being pressed. Thus, the folded portion 10 'is created. The bar 31 is disposed below the film body 1 ′, and the bar 32 is disposed above the film body 1 ′. In the case where a plurality of folded portions are provided, a plurality of the distorted portions are generated.

FIG. 10 shows another embodiment of the filter film body, and this filter film body includes a single folded portion 10 c that extends at an angle of about 30 ° with respect to the pleat fold. Such an oblique folded portion 10c is processed for each film body after the filter film body is cut to a predetermined length in the left-right direction.

Claims

The scope of the claims

[1] In a filter membrane body that is subjected to pleating processing in which mountain creases and valley creases are alternately provided, a fold portion that extends along a crossing direction that intersects the mountain crease and the valley crease is provided. The first fold and second fold force filter film bodies extending along the intersecting direction are folded back, and the filter film body is separated between the inner portion, the outer portion, and the inner and outer portions between the first and second folds. A filter membrane characterized in that it is tripled from the middle part of the filter.

[2] The filter film body according to claim 1, wherein the filter film body includes a force that also has a force of the filter film itself, or a filter film and a support laminated on one or both surfaces of the filter film.

[3] The filter membrane according to claim 1 or 2, wherein a plurality of the folded portions are provided.

[4] The filter membrane body according to any one of claims 1 to 3, wherein the filter membrane body is a cylindrical body incorporated in a cylindrical filter assembly.

[5] The inner portion and the middle portion of the folded portion form an outer pocket that communicates with the outer space of the filter membrane body therebetween, and the outer portion and the middle portion communicate with the inner space of the filter membrane body therebetween. The inner pocket is closed by the flow of fluid from the outer space to the inner space passing through the filter membrane body, and the inner pocket by the flow of fluid from the inner space to the outer space. 5. The filter membrane body according to claim 4, wherein the pocket is opened.

[6] The inner portion and the middle portion of the folded portion form an outer pocket that communicates with the outer space of the filter membrane body therebetween, and the outer portion and the middle portion communicate with the inner space of the filter membrane body therebetween. The inner pocket is closed by the flow of fluid from the inner space to the outer space passing through the filter membrane body, and the outer pocket by the flow of fluid from the outer space to the inner space. 5. The filter membrane body according to claim 4, wherein the pocket is opened.

[7] A method of manufacturing a filter membrane body that is subjected to pleating processing in which mountain folds and valley folds are alternately continued, and crosses a mountain fold and a valley crease that are attached later, before the pleating. Including a step of providing one or a plurality of folded portions extending, and the folded portions include first and second fold force filter film bodies extending along the intersecting direction. The filter membrane body is folded between the first and second folds, and the filter membrane body is tripled from an inner portion, an outer portion, and an intermediate portion between these inner and outer portions. Method.