JP2009285573A - Method for manufacturing pleated filter medium and filter unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a pleated filter medium which is suitable to carry out reliable connection of original fabric pieces and subsequent stable pleating processing even where two or more original fabric pieces are connected to one another to obtain one original fabric and then the original fabric is subjected to pleating processing. <P>SOLUTION: The method involves connecting two or more original fabric pieces to one another with a heat seal to obtain one original fabric and thereafter carrying out pleating processing of the original fabric. In the case where the original fabric pieces are treated by liquid-repelling treatment, heat sealing may be carried out in a state that an adhesive assisting material (for example, urethane nonwoven fabric) is set between the original fabric pieces. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a pleated filter medium and a filter unit including the filter medium obtained by the method.

  Filter units that remove particles in gases are widely used in clean room ventilation systems, air purifiers, vacuum cleaners, and the like. The filter unit generally has a structure in which a filter medium made of a nonwoven fabric, a porous membrane or the like is supported by a support frame (frame). The filter medium is usually pleated to increase the filtration area per unit volume as a filter unit (see Patent Document 1).

The pleated filter medium is manufactured by pleating the original fabric with a pleating machine. For example, when the raw fabric is in a belt shape, the raw fabric is continuously supplied to the pleating machine from a state wound around a roll. Note that the pleating process is a kind of bending process, and the main surface of the filter medium is a shape in which peaks and valleys extending alternately in a predetermined direction (the width direction in the case where the original fabric and the filter medium are strips) appear alternately by pleating. It becomes.
JP-A-11-253719

  By the way, when the original fabric has defects such as foreign matter and dirt, it is desired to remove the defects before pleating. In this case, as shown in FIG. 3, after the portion 6 including the defect 5 in the raw fabric 16 is cut out to a certain length L2, and the remaining portions 7 and 8 are connected to each other, the original fabric 1 after connection is removed. Pleated. At this time, the parts 7 and 8 are each part formed by dividing | segmenting the said original fabric 16 with the excision of a part (part 6) of the original fabric 16. FIG. Assuming that the portions 7 and 8 are the original fabric pieces 15a and 15b, the original fabric pieces 15a and 15b are connected to each other to become one original fabric 1, and then the original fabric 1 is pleated.

  Further, when exchanging the roll for supplying the belt-shaped original fabric to the processing machine, the end portion of the first original fabric fed from the roll to be exchanged and the second original fabric fed from the new roll. It is performed to connect the starting end of the material and to pleat the original fabric after the connection. Thereby, after completion of the pleating for the first original fabric, the roll can be exchanged more smoothly and the productivity of the filter medium can be improved as compared with the case where the second original fabric is passed again through the pleating machine. Here, when each of the first and second original fabrics is an original fabric piece, the original fabric pieces are connected to each other to become one original fabric, and then the original fabric is pleated.

  Conventionally, a double-sided tape is used for connecting the raw fabric pieces. However, in the connection using the double-sided tape, the connection strength between the raw fabric pieces is not sufficient, and the connection portion may be peeled off during pleating. In addition, the tape may adhere to the rolls and blades of the processing machine, and the production line may stop.

  Therefore, the present invention is a method for producing a pleated filter medium, and even when two or more original pieces are connected to each other to form one original, the original fabric is also pleated. It is an object of the present invention to provide a manufacturing method capable of reliably connecting pieces and performing stable pleating thereafter.

  The method for producing a pleated filter medium of the present invention is a production method including a step of pleating a filter filter medium, wherein two or more original pieces are connected to each other by heat sealing. And then pleating the original fabric.

  The filter unit of the present invention includes the filter medium obtained by the manufacturing method of the present invention and a support frame that supports the filter medium.

  According to the manufacturing method of the present invention, even when two or more original pieces are connected to each other to form one original, even when the original is pleated, Stable pleating can be performed.

  An example of the manufacturing method of the present invention will be described with reference to FIGS.

  In the method shown in FIG. 1, a strip-shaped raw fabric 1 is supplied to a pleating machine 3, which is pleated by the processing machine 3 to obtain a pleated filter medium 4. The filter medium 4 passes through a post-process such as cutting, and is then incorporated into, for example, a support frame to form a filter unit.

  The original fabric 1 is an original fabric obtained by connecting the strip-shaped original fabric pieces 15a and 15b to each other by heat sealing, as shown in FIG.

  The method shown in FIGS. 1 and 2 enables stable pleating of the original fabric 1 formed by reliable connection of the original fabric pieces 15a and 15b and connection of the original fabric pieces 15a and 15b.

  The structure of the raw fabric pieces 15a and 15b is not particularly limited as long as it can be connected by heat sealing and can be used as a filter medium after pleating. For example, the shape is not particularly limited, and is typically a rectangular shape or a belt shape. If the shape of at least one original fabric piece is a belt-like shape, the original fabric 1 formed by connecting the original fabric pieces becomes a belt-like shape, and the continuous filter medium 4 can be manufactured.

  For example, as shown in FIG. 3, the raw fabric pieces 15 a and 15 b are partly cut off and divided into a raw fabric 16 (hereinafter referred to as an original filter medium 16 in order to distinguish it from the original fabric 1 to be pleated). The respective portions 7 and 8 are formed by each of the above. The “part of the original filter medium 16” excised in the example shown in FIG. 3 is a portion 6 including the defect 5. In this case, the original fabric 1 from which the defect 5 existing in the original filter medium 16 has been removed. Is pleated.

  The original fabric pieces 15a and 15b are a first original fabric sent from a roll to be exchanged and a second original sent from a new roll at the time of exchanging the roll for supplying the belt-shaped original fabric to the pleating machine. It may be anti. In this case, as described above, the replacement of the roll becomes smooth, and the productivity of the filter medium 4 is improved.

  In the example shown in FIGS. 1 and 2, the number of original pieces to be connected is two, but the number of original pieces to be connected in the manufacturing method of the present invention is not particularly limited. For example, three or more original pieces are connected to each other. It is good also as one original fabric 1 by connecting.

  The position at which the heat-seal connection is made in the original fabric pieces 15a and 15b is not particularly limited as long as the original fabric 1 after connection can be pleated, but typically, as shown in FIG. End portions 9a and 9b. That is, in the manufacturing method of the present invention, two or more original fabric pieces may be connected to each other at the end of each original fabric piece.

  As shown in FIG. 4, the original fabric pieces 15a and 15b may be connected at positions away from the end portion of at least one original fabric piece (in the example shown in FIG. 4, from the end portion 14 of the original fabric piece 15b). The raw fabric pieces 15a and 15b are connected to each other at the connecting portion 10). In this case, after both raw fabric pieces are connected to each other, the end portion 14 of the at least one original fabric piece (original fabric piece 15b) is connected. The portion 11 from the first to the connecting portion 10 may be further excised.

  In the example shown in FIG. 2, heat sealing is performed such that the original fabric piece 15a and the original fabric piece 15b are in contact with each other, and both the original fabric pieces are connected. As described above, in the manufacturing method of the present invention, two or more original fabric pieces may be heat-sealed so that the original fabric pieces are in direct contact with each other, and may be connected to each other. In this case, unlike when the original fabric pieces are connected with the double-sided tape, no outgas is generated due to the connection method of the original fabric pieces. As a result, even when manufacturing filter media that are premised on use in high-standard creel rooms such as ULPA filters (Ultra Low Penetration Air Filter), where double-sided tape could not be used due to outgassing problems, A single connection is possible.

  In addition, when heat-sealing so that the original fabric pieces are in direct contact with each other, the original fabric pieces themselves need to be heat-sealable. Typically, the original fabric pieces include a heat-sealable material.

  The heat sealable material is, for example, a thermoplastic resin.

  Examples of the thermoplastic resin include polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene (PE), polypropylene (PP), and polytetrafluoroethylene (PTFE).

  In the manufacturing method of the present invention, as shown in FIG. 5, heat sealing is performed in a state in which the adhesion auxiliary material 12 is disposed between the original fabric piece 15 a and the original fabric piece 15 b, thereby connecting both the original fabric pieces to each other. May be. That is, in the manufacturing method of the present invention, two or more original fabric pieces may be heat-sealed in a state where an adhesion auxiliary material is disposed between the original fabric pieces and connected to each other.

  Depending on the intended use of the filter medium to be finally formed, an original film piece subjected to liquid repellent treatment (water repellent treatment and / or oil repellent treatment) is used. It is difficult to connect the liquid repellent treated strips with double-sided tape. In addition, when the original fabric pieces are subjected to a liquid repellent treatment, the connection strength may be reduced in heat sealing in which the original fabric pieces are brought into direct contact with each other. However, even in such a case, by performing heat sealing in which the adhesion auxiliary material is disposed between the raw fabric pieces, the connection strength is further improved, and stable pleating can be performed.

  The adhesion auxiliary material is, for example, a nonwoven fabric. In addition, the problem of outgas mentioned above can be avoided by using a nonwoven fabric for an adhesion auxiliary material.

  The nonwoven fabric is, for example, a urethane nonwoven fabric.

  The specific method of heat sealing is not particularly limited, and may be a known method.

  There are various methods such as an ultrasonic method, a heat method, and an impulse method for heat sealing, and an impulse method that requires a short time for applying heat to the original fabric piece and a cooling time after sealing is preferable.

  The heat seal width varies depending on the shape and size of the original fabric piece, but is usually about 1 to 5 cm. In the heat-sealed portion, the gas permeability as the filter medium 4 is lowered, so that the heat seal width is preferably not excessively large. On the other hand, if the heat seal width becomes excessively small, the connection strength between the original fabric pieces cannot be secured, and stable pleating of the original fabric 1 becomes difficult.

  The heat seal width is the length of the overlapping portion of the overlap pieces 15a and 15b (the overlap portion viewed from the direction perpendicular to the main surface of each of the original pieces) (see FIG. 2). L1) shown in FIG.

  The raw fabric piece is, for example, the above-described thermoplastic resin nonwoven fabric, woven fabric, mesh, felt, or porous membrane. In addition, the original fabric 1 (original fabric to be pleated) obtained by connecting two or more original fabric pieces to each other by heat sealing basically has the same configuration as the original fabric excluding the connection portion by heat sealing. . Moreover, the filter medium 4 obtained by pleating the original fabric 1 basically has the same configuration as the original fabric except that it is pleated.

  The raw fabric piece may have a PTFE porous membrane. In this case, a filter medium having a small pressure loss and a high collection efficiency can be obtained.

  The raw fabric piece may have a nonwoven fabric layer (PE-PET nonwoven fabric layer) containing PE fibers and PET fibers. In this case, a filter medium with a very small pressure loss can be obtained depending on the configuration of the raw fabric piece.

  In an original fabric piece having a PTFE porous membrane and / or a PE-PET nonwoven fabric layer, particles in the gas are removed by the porous membrane and the nonwoven fabric layer when it finally becomes a filter medium.

  The raw fabric piece may have a structure in which a PTFE porous membrane is sandwiched between PE-PET nonwoven fabric layers. As the raw fabric piece having such a structure, for example, a raw fabric piece having a three-layer structure of PE-PET nonwoven fabric layer / PTFE porous membrane / PE-PET nonwoven fabric layer, or PE-PET nonwoven fabric layer / PTFE porous membrane There is an original fabric piece having a five-layer structure of / PE-PET nonwoven fabric layer / PTFE porous membrane / PE-PET nonwoven fabric layer.

  The method for pleating the original fabric 1 formed by connecting the original fabric pieces is not particularly limited, and a known method may be followed. For example, the raw fabric 1 may be pleated by a pleating machine, but known processing machines employing various systems such as a reciprocating system and a rotary system can be used for the pleating machine as well.

  FIG. 6 shows an example of the filter unit of the present invention. A filter unit 21 shown in FIG. 6 includes a pleated filter medium 4 and a support frame 22 that supports the filter medium 4. The filter medium 4 is a filter medium obtained by the manufacturing method of the present invention described above.

  In addition, in FIG. 6, although illustration of the part (connection part) where the raw fabric pieces in the filter medium 4 are connected is omitted, also in the filter unit 21 actually manufactured, there is no connection part in the filter medium 4. There is. This is because, depending on the shape of the original fabric piece (particularly, when the original fabric piece has a long strip shape), only a small part of the original fabric 1 has a connecting portion. In addition, when the filter unit 21 is manufactured, the filter medium 4 can be cut so as to cut off the connection portion. In this case, no connection portion exists in the filter medium 4 of the manufactured unit 21.

  The support frame 22 may be made of a general material for the filter unit, such as ABS (acrylonitrile-butadiene-styrene) resin, polypropylene (PP) resin, polycarbonate resin, various elastomer resins, and the like. The support frame 22 is generally made of ABS resin or PP resin, but resins other than those listed above may be used. For example, considering the securing of dimensional accuracy as the support frame 22, the support frame 22 made of a resin mixed with glass fibers may be used.

  A specific method for forming the filter unit 21 is not particularly limited. For example, the support frame 22 may be insert-molded using the filter medium 4.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below.

  Initially, the evaluation method of the filter material produced by the present Example is shown.

[Pressure loss of filter media]
The prepared filter medium was set in a circular holder so that the effective filtration area was 100 cm ^2, and then a pressure difference was generated on both sides of the filter medium to allow gas to pass through the filter medium. Here, the pressure difference at which the linear velocity of the permeating gas was 5.3 cm / sec was measured with a manometer, and the measured pressure difference value was defined as the pressure loss (Pa) generated in the produced filter medium.

[Filtering efficiency of filter media]
The produced filter medium was set in a holder in the same manner as the measurement of pressure loss, and a pressure difference was generated on both sides of the filter medium to allow gas to pass through the filter medium. Next, after adjusting the pressure difference so that the linear velocity of the gas passing through the filter medium is 5.3 cm / sec, the polydispersed dioctyl phthalate (DOP) particles have a particle size of 0.1 to 0.15 μm. The concentration of DOP particles having a particle diameter of 0.1 to 0.2 μm on the upstream side and downstream side of the filter medium is set so that the concentration of the DOP particles is about 10 ⁷ particles / L. The concentration of DOP particles having a particle diameter of 3 to 0.4 μm was measured by a particle counter, and the collection efficiency of the filter medium for DOP particles having each particle diameter range was determined by the following formula.
Collection efficiency = {1− (downstream DOP particle concentration / upstream DOP particle concentration) × 100 (%)

(Example 1)
Two sheets of A4 size raw fabric (Nitto Denko, NTF9317-H01) having a three-layer structure in which a PTFE porous membrane is sandwiched between a pair of PE-PET nonwoven fabrics are prepared, and an impulse heat seal machine (Fuji Impulse) , OPL-600-10) were used to connect the two original fabric pieces together.

  The connection of the raw fabric pieces was performed as follows (see FIG. 7). First, the two original fabric pieces 15a and 15b were arranged side by side so as to be continuous in the surface direction when viewed from the direction perpendicular to the main surface of the original fabric pieces and to overlap each end. The length L3 in which both the original fabric pieces overlap was 3 cm.

  Next, a portion 32 of 1 cm or more and 2 cm or less from the edge 31a, 31b of each of the original fabric pieces 15a, 15b in the overlapping portion of the original fabric pieces 15a, 15b is heat sealed with a heating horn 33, and the original fabric pieces 15a, 15b are bonded. Connected. The heat seal width L1 is 1 cm.

  In addition, in heat-sealing an original fabric piece, the PTFE film (Nitto Denko make, No.903UL) was arrange | positioned as the release film 34 between the heating horn 33 and the original fabric pieces 15a and 15b. The heat sealing conditions were 160 ° C. and 5 seconds.

  Next, the original fabric obtained by connecting the original fabric pieces 15a and 15b by heat sealing was pleated by a pleating machine (TK-11, manufactured by Toyo Koki Co., Ltd.) to obtain a pleated filter medium. The height of the pleated peak was 20 mm.

(Example 2)
Except for using a raw fabric piece (manufactured by Nitto Denko, NTF9522-U01) having a five-layer structure of PE-PET nonwoven fabric layer / PTFE porous membrane / PE-PET nonwoven fabric layer / PTFE porous membrane / PE-PET nonwoven fabric layer In the same manner as in Example 1, a pleated filter medium was obtained.

(Example 3)
A pleated filter medium was obtained in the same manner as in Example 1, except that the liquid-repellent treated raw fabric piece (NTF9317-H01 used in Example 1 was subjected to liquid-repellent treatment) was used. In addition, the liquid repellent treatment of NTF9317-H01 is performed on a treatment liquid obtained by dissolving 1 kg of a liquid repellent treatment agent (X-70-02913 manufactured by Shin-Etsu Silicone) in 9 kg of a solvent (FC-5060 (3M) manufactured by Sumitomo 3M). NTF9317-H01 was immersed and dried.

Example 4
Pleat processing is performed in the same manner as in Example 3 except that when the two original pieces are connected by heat sealing, a urethane nonwoven fabric (KB Selen, Espancione) is disposed between the two original pieces. A filtered filter medium was obtained. The shape of the urethane nonwoven fabric was the same as that of the heat seal portion (connection portion) of the original fabric piece as seen from the direction perpendicular to the main surface of the original fabric piece. Moreover, the urethane nonwoven fabric was arrange | positioned so that it might exist in the whole connection part, when it sees from the said direction.

(Comparative Example 1)
A pleated filter medium was obtained in the same manner as in Example 1 except that the two original fabric pieces were connected not by heat sealing but by double-sided tape (manufactured by Nitto Denko, No. 500). In addition, the shape of the double-sided tape was the same shape as the heat seal part (connection part) in the filter medium produced in Example 1 when viewed from the direction perpendicular to the main surface of the original fabric piece.

(Comparative Example 2)
A pleated filter medium was obtained in the same manner as in Example 2 except that the two sheets of raw fabric were connected not by heat sealing but by double-sided tape (manufactured by Nitto Denko, No. 500). In addition, the shape of the double-sided tape was the same shape as the heat seal part (connection part) in the filter medium produced in Example 2 when viewed from the direction perpendicular to the main surface of the original fabric piece.

(Comparative Example 3)
Example except that NTF9317-H01 subjected to liquid repellent treatment by the method described in Example 3 was used as a raw fabric piece, and double-sided tape (Nitto Denko, No. 500) was used instead of heat sealing to connect the raw fabric pieces. In the same manner as in Example 1, an attempt was made to produce a pleated filter medium. However, the original fabric piece and the original fabric piece were not adhered by the double-sided tape, and an original fabric to be pleated could not be produced.

  The pressure loss and the collection efficiency were evaluated on the pleated filter material produced in each Example and Comparative Example (excluding Comparative Example 3) and the original fabric before pleating. In addition, it was visually confirmed whether or not peeling occurred at the connecting portion of the raw fabric piece (the connecting portion by heat sealing or double-sided tape) by pleating. The evaluation results are shown in Table 1 below.

  In addition, the measurement of the pressure loss and collection efficiency with respect to the original fabric before pleating was performed in the same manner as the measurement of the pressure loss and collection efficiency with respect to the pleated filter medium. In addition, when evaluating pressure loss and collection efficiency with respect to the pleated filter medium and the original pleated material, the ratio of the connecting portion of the original fabric piece in the effective filtration area was made the same. .

  As shown in Table 1, in Comparative Examples 1 and 2 in which the raw fabric pieces were connected with the double-sided tape, peeling occurred in the connecting portion due to the shearing force applied during pleating, and leakage from the peeled portion caused the filter media to be separated. Pressure loss and collection efficiency could not be measured. In addition, the collection efficiency has been lowered because there is already a minute leak in the connection portion before the pleating process.

  On the other hand, in Examples 1 to 4 in which the original fabric pieces are connected by heat sealing, it is possible to reliably connect the original fabric pieces and to perform stable pleating, and particularly in Examples 1, 2, and 4. Also, the collection efficiency did not decrease by pleating. In Example 3 using the liquid repellent treated fabric piece, the collection efficiency was reduced by the pleating process, but compared with Comparative Examples 1 and 2 in which the collection efficiency and the pressure loss could not be measured after the pleating process, Pleated workability was greatly improved.

  In addition, from the results of Examples 3 and 4, when using a liquid repellent treated raw fabric piece, the connection strength can be improved by heat sealing in which a urethane nonwoven fabric is arranged between the raw fabric pieces, and the pleating process is more stable. It was found that it can be implemented.

  According to the present invention, it is possible to stably manufacture a pleated filter medium and a filter unit including the filter medium, particularly a filter unit having a high collection efficiency such as ULPA.

  The filter medium and the filter unit obtained by the production method of the present invention can be used for various devices such as a clean room ventilation system, an air cleaner, and a vacuum cleaner.

It is a schematic diagram for demonstrating an example of the manufacturing method of the filter media which carried out the pleating process of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the filter media which carried out the pleating process of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the filter media which carried out the pleating process of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the filter media which carried out the pleating process of this invention. It is a schematic diagram for demonstrating an example of the manufacturing method of the filter media which carried out the pleating process of this invention. It is a schematic diagram which shows an example of the filter unit of this invention. It is a schematic diagram for demonstrating the heat sealing method of the original fabric piece in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Original fabric 3 Pleating machine 4 Filter filter medium 5 Defect 6 Part 7 Part 8 Part 9a, 9b End part 10 Connection part 11 Part 12 Adhesive auxiliary material 14 End part 15a, 15b Original fabric piece 16 Original fabric (original filter medium)
21 Filter unit 22 Support frame 31a, 31b Edge 32 Part 33 Heating horn 34 Release film

Claims (11)

A method for producing a pleated filter media comprising a step of pleating a filter filter stock,
A method for producing a pleated filter medium, wherein two or more original pieces are connected to each other by heat sealing to form one original, and then the original is pleated.   2. The method for producing a pleated filter medium according to claim 1, wherein the two or more original fabric pieces are parts formed by cutting and dividing a part of a strip-shaped original filter medium.   The method for producing a pleated filter medium according to claim 1, wherein the two or more original fabric pieces are connected to each other at an end portion of each original fabric piece.   The method for producing a pleated filter medium according to claim 1, wherein the two or more original fabric pieces are heat-sealed so that the original fabric pieces are in direct contact with each other, and are connected to each other.   The method for producing a pleated filter medium according to claim 1, wherein the two or more original fabric pieces are heat-sealed in a state where an adhesion auxiliary material is disposed between the original fabric pieces and connected to each other.   6. The method for producing a pleated filter medium according to claim 5, wherein the original piece is subjected to a liquid repellent treatment.   The method for producing a pleated filter medium according to claim 6, wherein the adhesion auxiliary layer is a urethane nonwoven fabric.   The method for producing a pleated filter medium according to claim 1, wherein the raw fabric piece has a polytetrafluoroethylene (PTFE) porous membrane.   The method for producing a pleated filter medium according to claim 1, wherein the raw fabric piece has a nonwoven fabric layer containing polyethylene (PE) fibers and polyethylene terephthalate (PET) fibers.   The method for producing a pleated filter medium according to claim 1, wherein the raw fabric piece has a structure in which a PTFE porous membrane is sandwiched between nonwoven fabric layers containing PE fibers and PET fibers.   A filter unit comprising a pleated filter medium obtained by the manufacturing method according to claim 1 and a support frame that supports the filter medium.

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