JP2009066534A - Pleated filter cartridge for liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pleat type filter cartridge for liquid using polymer-based nano-fiber nonwoven fabric, having required level of completeness and pressure resistance, and stably manufacturable. <P>SOLUTION: The polymer-based nano-fiber nonwoven fabric is sandwiched with support materials and the support materials are pressedly integrated with the nano-fiber nonwoven fabric by laminating to form a filter. Diameters of the support materials serving as the secondary side of the filter are set to 1-10 μm, to enhance the pressure resistance of the polymer-based nano-fiber nonwoven fabric. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel pleated filter cartridge using a polymer nanofiber nonwoven fabric having pressure resistance that can be used as a filter for liquid filtration.

  Polymer nanofiber nonwoven fabrics are generally known as gas filtration filters that have a low viscosity and do not generate a large differential pressure because of their weak binding strength between fibers. However, there is no known filter having pressure resistance that can be used industrially as a liquid filter requiring pressure resistance against a fluid.

  In the case of a pleated filter cartridge for liquids, especially in a filter cartridge using a microfiltration membrane (PTFE membrane or PE membrane) that guarantees completeness, the filter media is used for the purpose of protecting the microfiltration membrane that is the main filter medium. Support material is used before and after. As this support material, since the support effect increases as the strength increases, a nonwoven fabric having a large fiber diameter such as spunbond (SB) has been used.

  The polymer nanofiber nonwoven fabric is expected to have the same filtration accuracy as this membrane filter, so if the nanofiber nonwoven fabric can be used as a precision filter material, the porosity can be increased more than the membrane filter. This is advantageous in that it can be made smaller.

  Since the above advantages are expected, an attempt was made to use a laminated body in which both sides of the polymer nanofiber nonwoven fabric were sandwiched between support materials as a pleated filter for liquids. If a high-strength, large-fiber-diameter, coarse support material that is normally used as a support material for membrane filters is made secondary, the polymer nanofiber nonwoven fabric will open with hydraulic pressure, and the filtration accuracy will increase. It turned out to be reduced.

  In order to solve this problem, as a support material of a conventional membrane filter, a fine support material that is not effective as a support material than a coarse spunbond nonwoven fabric (SB) is used as shown in FIG. The secondary side of the filter was found to reduce the opening of the polymer nanofiber nonwoven fabric, but it was found that this filter did not reach the required level of integrity and pressure resistance. .

  The present invention has been made paying attention to such a point, and the pleated type for liquids using a polymer nanofiber nonwoven fabric that can achieve a required level of integrity and pressure resistance and can be stably produced. An object is to provide a filter cartridge.

  In order to achieve the above object, the present inventor, as a result of earnest research, made the secondary side shown in FIG. 1 a support material having a fiber diameter of 1 to 10 μm, and sandwiched both support materials and a polymer nanofiber nonwoven fabric. It has been found that a liquid pleated filter cartridge having the required integrity and pressure resistance can be stably produced by laminating and bonding the laminate by laminating, and the present invention has been achieved.

  That is, the present invention is formed by sandwiching a polymeric nanofiber nonwoven fabric with a support material, and laminating the support material and the nanofiber nonwoven fabric, and the secondary side has a fiber diameter of 1 to 10 μm. It is made of support material.

It is preferable that the filter medium obtained by laminating the polymer nanofiber nonwoven fabric on the support material and the support material are pressure-bonded and integrated by laminating (Claim 2).
It is preferable to press-fit and integrate to a filter medium porosity of 50 to 80% by laminating by calendering.

  The laminating process is preferably an embossing roll laminating process because the area of pressure bonding is small and the overall porosity can be kept high.

It is preferable that the embossing rolls form a large number of pressure-bonding parts having a closed shape around the non-compressed part or a substantially closed shape having a communicating part communicating with the adjacent non-compressed part (Claim 5). It is preferable that a single area of the non-compressed portion which is closed or almost closed is 20 mm ² or less (Claim 6).

It is preferable that the plurality of communicating portions with which the adjacent non-compressed portions communicate are not in the same straight line in the communicating direction (Claim 7). When there are two or more communicating portions, it is preferable that at least two communicating portions are not on the same straight line.
By laminating with the embossing roll, it is preferable that the pressure-bonding area ratio is 20 to 60% of the whole and the filter medium porosity of the pressure-bonding portion is 10 to 70%.

The support material melts at a temperature equal to or higher than that of the polymer nanofiber nonwoven fabric, which increases the penetration strength into the weld plate, so that the end face of the pleated filter is sealed during the heat welding process. Is preferable because it can be performed completely (claim 9).

The nanofiber nonwoven fabric preferably has a fiber diameter of 5 to 1000 nm and a basis weight of 0.2 to 10 g / m ² (claim 10).

The primary side support material preferably has a fiber diameter of 10 to 30 μm, and the secondary side support material preferably has a fiber diameter of 1 to 10 μm. The basis weight of the primary side and secondary side support materials is preferably 10 to 100 g / m ² (claim 12).

  According to the present invention, a polymer nanofiber nonwoven fabric, which has been conventionally considered to be unusable as a precision filter material for a liquid pleated filter, is used as a pressure proof liquid pleated filter precision filter material. This is the first successful method, and it is possible to make a filter having a larger porosity than a membrane filter, and it is expected that the pressure loss is reduced and cost reduction is also expected.

  The cause of the effect of the present invention lies in that a fine support material is used on the secondary side, and the nanofiber nonwoven fabric and the front and back support materials are bonded together by lamination. In the present invention, the pressure-bonding integration means that each layer does not move freely, but is pressure-bonded to a part or all of the filter to such an extent that the nanofiber nonwoven fabric does not melt.

  Next, an embodiment of the present invention will be described.

  In order to sandwich a polymer nanofiber nonwoven fabric with a support material and compress it by laminating and integrating it, a filter material in which the nanofiber nonwoven fabric is laminated on the support material is used to protect the surface layer of the nanofiber nonwoven fabric. It is better to press-fit the supporting material to be integrated.

  The secondary side of the liquid pleated filter cartridge is a support material having a fiber diameter of 1 to 10 μm. Examples of such a material include a melt blown (MB) nonwoven fabric. By using a support material having such a fiber diameter on the secondary side, the opening of the nanofiber nonwoven fabric can be effectively prevented.

  It is preferable to compress and integrate the filter medium with a porosity of 50 to 80% by laminating by calendering. If the filter medium porosity is too small, ΔP will increase, and if it is too high, pressure resistance will decrease.

  Lamination by calendering may be performed by ordinary lamination, but it is necessary to press-bond to such an extent that the polymer nanofiber nonwoven fabric does not melt.

  Lamination with an embossing roll is preferable because the pressure-bonding area ratio is 20 to 60% of the whole, and the filter medium porosity of the pressure-bonding part is 10 to 70%, because the pressure-resistant performance can be improved without significantly increasing ΔP. . This does not melt the nanofiber nonwoven fabric as in normal embossing. The crimping area ratio (%) is obtained from the crimping area ratio (%) = (B part area) / (A part area + B part area) × 100 as shown in FIG.

By embossing roll, forming many closed parts with closed shape around the non-compressed part or communication parts where the adjacent non-compressed parts communicate with each other (so that many non-compressed parts are independent from each other) However, the pressure-bonding area can be reduced, the overall filter medium porosity can be kept high, the opening of the nanofiber nonwoven fabric in the closed shape or the almost closed shape can be prevented, and the pressure resistance can be improved. Examples of the closed shape include, but are not limited to, a polygon, a circle, and an ellipse. A hexagonal shape, a quadrangular shape, a triangular shape, or the like is preferable because a large number of embossed portions having the same shape can be provided continuously.
As shown in FIG. 2, the individual area (A part) of the closed or almost closed non-compressed part is preferably 20 mm ² or less. Further, when the plurality of communicating portions (openings) communicating with the adjacent non-compressed portions are in the same straight line in the communicating direction, as shown in a and b of FIG. 3A, opening in the communicating direction occurs. As shown in FIG. 3B, when the communication portions are not on the same straight line in the communication direction, the opening is prevented.

  The support material may be a material that melts at a temperature equal to or higher than that of the polymer nanofiber nonwoven fabric. To that end, it is sufficient to use a support material having the same melting point or higher melting point, but even if the support material has a slightly lower melting point than the nanofiber nonwoven fabric, it is the same as the nanofiber nonwoven fabric due to the large fiber diameter. Or it can be melted at a higher temperature. If such a support material is used, it is possible to completely seal the end face of the prep filter during the heat welding process.

Fiber diameter of the nanofiber nonwoven fabric is 5 to 1000 nm, a basis weight is preferably between 0.2 to 10 g / ^{m 2.} If the fiber diameter is too small, the pore size will not be stable, and if it is too large, it will be inappropriate as a microfiltration material.
The fiber diameter of the support material on the secondary side is preferably 1 to 10 μm, and the fiber diameter of the support material on the primary side is preferably 10 to 30 μm.

The basis weight of the primary side and secondary side support materials is preferably 10 to 100 g / m ² . This is because if the basis weight is too small, the nanofiber nonwoven fabric may be exposed.

As the polymer nanofiber nonwoven fabric, those formed by electrospinning are preferably used. For example, single or plural resins such as PA, PVA, PAN, PVDF, PES, PS, PET, PU, PP, etc. Manufactured from the above.
As the support material, for example, PA, PVA, PVDF, PES, PS, PET, PU, PP, glass, ceramics, carbon, and the like can be suitably used.

EXAMPLES Next, although an Example and a comparative example are given and this invention is further demonstrated, this invention is not limited to these Examples. In addition, what was formed by the electrospinning method was used for the polymeric nanofiber nonwoven fabric used by the Example and the comparative example.
Comparative Example 1
By simply laminating the support material described in the following table 1 on the polymer nanofiber nonwoven fabric (● in the table) laminated on the spunbond (SB), a pleated filter cartridge for liquid is produced, and the filter moldability, Integrity, pressure resistance and ΔP (pressure loss) were measured. The results are shown in Table 1 below.

In the table, the mark ● means that the substrate is a polymer nanofiber nonwoven fabric (on which nanofiber nonwoven fabrics are laminated).

  From the above results, the pressure resistance of the filter is improved by using fine blown fibers (MB) on the secondary side (c) (c). However, even with this structure, the target pressure resistance performance (0.55 MPa × 10 times pulse load) has not been achieved.

Example 1
Laminate the support materials listed in the following table 2 on the polymer nanofiber nonwoven fabric (marked with ● in the table) laminated on the spunbond (SB), and laminate by calendering (d, e) and embossing roll (f) After integration by processing, a pleated filter cartridge for liquid was prepared, and the moldability, integrity, pressure resistance and ΔP of the filter were measured. The results are shown in Table 2 below.

As is clear from the above results, the pressure resistance performance has jumped dramatically by using a fine support material (MB) on the secondary side and integrating the three layers of support material, nanofiber nonwoven fabric and secondary side support material. Improved.
FIG. 4 shows f used in the above embodiment. As shown in FIG. 4, it is considered that the fibers open in the direction of the arrow when pressure is applied to the mark ● of f (compression bonding ratio: about 30%).
As described above, f is considered to have a high pressure resistance because the opening range is small. The reason why e is the highest pressure resistance performance is considered to be that the entire three layers are integrated and difficult to open, but ΔP is increased in the laminate by calendering.
Comparative Example 2
The polymer nanofiber non-woven fabric laminated on spunbond (SB) (● in the table) is laminated with the calendared MB non-woven fabric listed in the following table 3 as a support material to produce a pleated filter cartridge for liquid. The filter moldability, completeness, pressure resistance and ΔP were measured. The results are shown in Table 3 below.
Even when the calendared MB nonwoven fabric is used, it is not pressure-integrated by lamination, so the pressure resistance is low, and it cannot be used as a liquid pleated filter cartridge.
Example 2
Next, the pressure resistance performance test and the flow rate characteristic measurement were performed using the filter. The test conditions are as follows.
(Pressure performance test conditions)
Clogging substance: Milk Test pressure: Positive pressure (0.2, 0.3, 0.4, 0.55 MPa)
Temperature: Normal temperature Flow rate: 10-13 L / min
Interval: pressurization 10 seconds, rest 5 seconds (pressure resistance performance test method)
(1)
Clog the filter with milk.
(2)
Pulsating at the above test flow rate and predetermined pressure.
(Completeness confirmation test)
Confirmed by diffusion test.
(3)
A completely wetted filter is set in the housing and pressurized to 0.02 MPa.
(4)
The flow rate of the gas pushed out to the secondary side is measured.
As is apparent from the above results, the liquid pleated filters e and f of the present invention do not increase the diffusion air flow rate by integrating the secondary side with a support material having a fiber diameter of 1 to 10 μm by laminating. It can be seen that the filter cartridge can guarantee a completeness and have pressure resistance.
Example 3
The filter was set in the housing, pressure gauges were installed on the IN side and OUT side of the filter, the pressure on the IN side and OUT side at each flow rate was measured, and the difference was recorded as the differential pressure (MPa). The results are shown in Table 5 below.
(Measurement conditions for flow characteristics)
Fluid: Purified water temperature: Room temperature Flow rate: 10, 20, 30, 40 L / min
Filter size: 250mm
From the above result, the pressure loss is higher in the case where the whole is pressure-bonded and integrated by calendering (e) than in the case of (f) partly pressure-integrated and integrated by embossing roll. The flow rate characteristics of the pleated filters e and f for liquid of the invention are sufficiently suitable for practical use.
Example 4
The pleats prepared from the polymer nanofiber nonwoven fabric and the support material shown in the following Table 6 were heat-welded to the plate, and the integrity was confirmed. The results are shown in the following Table 6 and FIG.
As apparent from Table 6 and FIG. 5, since PP has a lower melting point than PA, PP of the primary side support material is melted in the filter (1), and the nanofiber nonwoven fabric layer is exposed and scratched. Moreover, foaming from the plate end face was also confirmed.
Since the filter (2) uses the same PA as the nanofiber nonwoven fabric layer for the primary side support material, the melting point is the same, so foaming from the end face of the plate does not occur.
Next, the detailed structure of the pre-filter used in the above examples and comparative examples is shown.
Detailed structure of b
c detailed structure
d detailed structure
e detailed structure
Detailed structure of f
Detailed structure of g

It is a perspective view of the pleated filter cartridge using the nanofiber nonwoven fabric of the present invention. It is the schematic (closed shape) of the filter laminated by the embossing roll of this invention. It is the schematic of the filter of the almost obstruct | occluded shape laminated by the embossing roll of this invention, (A) Opening part continuous structure, (B) Opening part discontinuous structure. It is the photograph (x25 time) of the filter laminated by the embossing roll of this invention. It is a photograph (x100 times) of the result of carrying out the integrity test by thermally welding the pleat which consists of a structure of Table 6- (1) to a plate.

Claims (12)

A polymer nanofiber non-woven fabric is sandwiched between support materials, and the support material and the nanofiber non-woven fabric are bonded together by laminating to form a filter, and fibers of the support material that becomes the secondary side of the filter A pleated filter cartridge for liquid having a diameter of 1 to 10 μm. The filter cartridge according to claim 1, wherein a filter medium in which a polymer nanofiber nonwoven fabric is laminated on a support material and the support material are integrated by pressure bonding by laminating. The filter according to claim 1 or 2, wherein the filter medium is pressure-bonded and integrated to a porosity of 50 to 80% by laminating by calendering. The filter cartridge according to claim 1, wherein the laminating process is a laminating process using an embossing roll. 5. The filter cartridge according to claim 4, wherein the embossing roll forms a large number of pressure-bonding portions having a closed shape around the non-compressed portion or a communication portion that communicates with an adjacent non-compressed portion. The filter cartridge according to claim 5, wherein a single area of the closed or almost closed uncompressed portion is 20 mm ² or less. 7. The filter cartridge according to claim 5, wherein the plurality of communicating portions that communicate with the adjacent non-compressed portions are not in the same straight line in the communicating direction. 8. The filter cartridge according to claim 6, wherein, by laminating with the embossing roll, the pressure-bonding area ratio is 20 to 60% of the whole, and the filter medium porosity of the pressure-bonding portion is 10 to 70%. The filter cartridge according to any one of claims 1 to 8, wherein the support material melts at a temperature equal to or higher than that of the polymer-based nanofiber nonwoven fabric. Fiber diameter of the polymer-based nanofiber nonwoven fabric is 5 to 1000 nm, a basis weight, the filter cartridge according to any one of claims 1 to 9 is 0.2 to 10 g / ^{m 2.} The filter cartridge according to any one of claims 1 to 10, wherein the support material on the primary side has a fiber diameter of 10 to 30 µm. The basis weight of the primary and secondary sides of the support material, the filter cartridge according to any one of claims 1 to 11 is 10 to 100 g / ^{m 2.}