JP2001340732A - Laminated filter element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated filter element with a simple constitution capa ble of effectively removing the solid components contained in a fluid to be filtered and the gelatinous components with diameters smaller than that of the filter pore at a most downstream side. SOLUTION: PTFE filter layers are preferably arranged on a upstream side with respect to the flow of fluid to be filtered and polyolefin filter layers are arranged on a downstream side with respect to the flow of the fluid to be filtered and at this time, the PTFE filter membrane of the larger pore diameter of a pair of the PTFE filter membranes constituting the PTFE filter layers is at least arranged on the upstream side and the PTFE filter membrane of the smaller pore diameter is arranged on the downstream side. In the composite membrane filter having such constitution, the solid components in the fluid to be filtered are separate by the PTFE filter layers and the gelatinous components in the fluid to be filtered are separated by the polyolefin filter layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for converting a fluid to be filtered from a fluid containing a solid component and a gel component having a diameter substantially smaller than the pore diameter of the most downstream filtration membrane for removing the solid component. The present invention relates to a laminated filter element capable of effectively removing a filtration substance.

[0002]

2. Description of the Related Art Since a solid component and a gel component are mixed in a photoresist during a manufacturing process, it is necessary to remove it. Generally, PTFE (polytetrafluoroethylene, ie, polytetrafluoroethyl)
ene) is effective for filtration of solid foreign matter, but requires extremely fine pore size to remove gel-like components, and requires a large operating pressure during filtration. Therefore, the filtration efficiency has been reduced.
On the other hand, it is known that a filter element made of a polyolefin filtration membrane is effective for filtering gel-like foreign matter. For this reason, conventionally, the filter in the photoresist is subjected to multi-stage filtration by using a filter element using PTFE as a filtration membrane material and a filter element using a polyolefin filtration membrane material represented by polyethylene, respectively. Removes solid components and gel components.

[0003]

Conventionally, the foreign matter in the photoresist has been removed by multi-stage filtration, so that the filtration process must be complicated. For this reason, not only the maintenance and inspection work of the filtration device is difficult, but also it is difficult to improve the filtration efficiency.

[0004] An object of the present invention is to effectively remove solid components mixed in a fluid to be filtered and a gel component having a diameter smaller than the pore diameter of the most downstream filtration membrane for removing solid components. It is an object of the present invention to provide a laminated filter element having a simple structure that can be used.

In the present invention, a gel component having a diameter substantially smaller than the pore diameter of the most downstream filtration membrane for removing solid components is defined as a gel component which passes through the pore diameter of the most downstream filtration membrane for removing solid components. Means a gel component having a diameter smaller than the diameter that can be obtained, and the pore size is measured by a bubble point test method of JIS K 3832 microfiltration membrane element and module, and is measured by a bubble point when air bubbles are recognized from the entire surface of the filter. Pore diameter, that is, substantially the average pore diameter.

The fluid to be treated by the laminated filter element of the present invention is a fluid containing a solid component and a gel component having a diameter substantially smaller than the pore diameter of the most downstream filtration membrane for removing the solid component. However, the present invention is not limited to photoresist.

[0007]

According to the present invention, there is provided a laminated filter element comprising a P filter formed of a PTFE filtration membrane.
A TFE filtration layer, constituted by combining a polyolefin filtration layer constituted by a polyolefin filtration membrane,
Composite material, so-called composite membrane filter element, PT
And a single-material laminated filter element configured using one of the FE filtration layer and the polyolefin filtration layer.

As the polyolefin filtration membrane in the present invention, a porous membrane and / or a microporous membrane formed from a polyolefin such as polypropylene or polyethylene having a low molecular weight to an ultra-high molecular weight and polyethylene mixed with them can be applied. A porous membrane and / or a microporous membrane can be applied to the PTFE filtration membrane.

[0009] Among the laminated filter elements of the present invention, the laminated filter element having a configuration corresponding to a composite membrane filter is formed by laminating a plurality of PTFE filtration membranes on a PTFE filtration layer. At least one pair of PTFE filtration membranes among the PTFE filtration membranes has a different pore size for each PTFE filtration membrane.

This composite membrane filter element is made of PTF
An E-filter layer disposed upstream with respect to the flow of the fluid to be filtered;
It is desirable to arrange the polyolefin filtration layer on the downstream side with respect to the flow of the fluid to be filtered. At this time, of the at least one pair of PTFE filtration membranes, P
The TFE filtration membrane is arranged on the upstream side, and the smaller pore size P
The TFE filtration membrane is located downstream.

[0011] The polyolefin filtration membrane has a property of trapping the gel-like component more effectively than the PTFE filtration membrane having the same pore size, and even if it is several times larger than the pore size of the PTFE filtration membrane, the gel-like component is not removed. Since the capturing property is not significantly impaired, a polyolefin filtration membrane layer can be arranged between the PTFE filtration membrane layers. These two filtration membrane layers are arranged such that the pore diameter decreases continuously and / or stepwise from the upstream side to the downstream side with respect to the flow of the fluid to be filtered. In the composite membrane filter element having such a configuration, it is possible to simultaneously filter the solid component and the gel component in the fluid to be filtered, and this is caused by using an ultra-fine pore size PTFE filtration membrane as conventionally performed. The operating pressure during filtration can be greatly reduced.

The composite membrane filter element of the present invention has a P
The TFE filtration layer can be constituted by laminating a pair of PTFE filtration membranes, and the polyolefin filtration layer can be constituted by a single polyolefin filtration membrane.

As the PTFE filtration membrane, a thin film formed by a stretching method can be used. As the polyolefin filtration membrane, a thin film by a phase separation method or a thin film by a stretching method can be applied. When the polyolefin filtration membrane layer is arranged for the purpose of filtering the gel component and pre-filtration, a nonwoven fabric may be arranged on the upstream side of the polyolefin filtration layer with respect to the flow of the fluid to be filtered.

The nonwoven fabric has a density gradient that increases from the upstream side to the downstream side of the fluid to be filtered (the gradient of the porosity is reduced), the nonwoven fabric has a reduced fiber diameter, It is preferable that the fiber diameter is reduced while maintaining the ratio at a certain preferable constant value. However, a fiber having a reduced fiber diameter at a uniform density or a fiber having a constant fiber diameter is also applicable.

According to the composite membrane filter element of the present invention, of the pair of PTFE filtration membranes, the upstream PTFE filtration membrane has a pore size of 0.45 to 10 μm and the downstream PTFE filtration membrane has a pore size of 0.45 to 10 μm.
The pore diameter of the FE filtration membrane can be 0.05 to 0.45 μm, and the pore diameter of the polyolefin filtration membrane can be 0.1 to 1.0 μm.

The multilayer filter element of the present invention has a P
A PTFE filtration layer is formed by laminating a plurality of PTFE filtration membranes using TFE as a filtration membrane material.
Of the E filtration membrane, at least one pair of PTFE filtration membranes,
The PTFE filtration membrane is configured to have a different filtration aperture. Here, of the at least one pair of PTFE filtration membranes, the PTFE filtration membrane having a larger filtration aperture is disposed on the upstream side with respect to the flow of the fluid to be filtered, and the PTFE filtration membrane having a smaller pore diameter is the flow of the fluid to be filtered. Is located downstream.

In the laminated filter element of the present invention, a polyolefin filtration layer is formed by laminating a plurality of polyolefin filtration membranes using polyolefin as a filtration membrane material, and at least one pair of the polyolefin filtration membranes among the plurality of polyolefin filtration membranes is used. It can be configured so that each polyolefin filtration membrane has a different pore size. At this time, among the at least one pair of polyolefin filtration membranes, the polyolefin filtration membrane having a larger pore diameter is disposed upstream with respect to the flow of the fluid to be filtered, and the polyolefin filtration membrane having the smaller pore diameter is arranged with respect to the flow of the fluid to be filtered. It is desirable to be located downstream.

The laminated filter element of the present invention, including the above-described composite filter element, is bent in a pleated shape in a state where the filter layers are overlapped with the support / drain layers 13 and 14 as shown in FIG. After being molded, the multilayer filter element can be formed into a cylindrical shape as a whole as shown in FIG.

The pleat shape may be such that the longitudinal direction of the pleated portion is parallel or perpendicular to the axial direction of the core 20 so that the wall surfaces of adjacent pleats do not contact each other as much as possible. Support layer / Drainage layer 13, 14
May be omitted.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In order to test the filtration life of a multilayer filter element of the present invention and the cleanliness of a fluid to be filtered after filtration, the multilayer filter elements A, B, C, and D having the following configurations are described. , E were prepared and tested by the following test methods using the test solutions shown below. (1) The laminated filter element A was composed of only a PTFE filtration layer, and this PTFE filtration layer was constituted by laminating three PTFE filtration membranes. Upstream PT
The pore size of the FE filtration membrane is 0.1 μm,
The pore diameter of the E filtration membrane was 0.05 μm, and the pore diameter of the intermediate PTFE filtration membrane was 0.1 μm. (2) The laminated filter element B was composed of only a polyethylene filtration layer, and this polyethylene filtration layer was constituted by laminating three polyethylene filtration membranes. The pore diameter of the most upstream polyethylene filtration membrane is 0.45 μm, and the pore diameter of the most downstream polyethylene filtration membrane is 0.15 μm.
m and the pore size of the intermediate polyethylene filtration membrane is 0.45μ.
m. (3) The multilayer filter element C is a pair of PTFE
A PTFE filtration layer constituted by laminating filtration membranes and a polyethylene filtration layer constituted by a single polyethylene filtration membrane were laminated. Of the pair of PTFE filtration membranes constituting the PTFE filtration layer, the upstream PT
The pore size of the FE filtration membrane is 0.45 μm,
The pore size of the E filtration membrane was 0.1 μm. Then, the pore size of the polyethylene filtration membrane constituting the polyethylene filtration layer is set to 0.
The thickness was 45 μm. The multilayer filter element C is made of PT
The FE filtration layer was arranged on the upstream side and the polyethylene filtration layer was arranged on the downstream side, and subjected to the test described above. (4) The multilayer filter element D is a pair of PTFE
A PTFE filtration layer constituted by laminating filtration membranes and a polyethylene filtration layer constituted by a single polyethylene filtration membrane were laminated. Of the pair of PTFE filtration membranes constituting the PTFE filtration layer, the upstream PT
The pore size of the FE filtration membrane was set to 5.0 μm, and the downstream PTFE was used.
The pore size of the filtration membrane was 0.1 μm. And the pore size of the polyethylene filtration membrane constituting the polyethylene filtration layer is 0.4
The thickness was 5 μm. The multilayer filter element D is made of PTF
The E filtration layer was disposed on the upstream side and the polyethylene filtration layer was disposed on the downstream side, and subjected to the above-mentioned test. (5) The multilayer filter element E is a pair of PTFE
A PTFE filtration layer constituted by laminating filtration membranes and a polyethylene filtration layer constituted by a single polyethylene filtration membrane were laminated. Of the pair of PTFE filtration membranes constituting the PTFE filtration layer, the upstream PT
The pore size of the FE filtration membrane is 10.0 μm,
The pore size of the E filtration membrane was 0.1 μm. Then, the pore size of the polyethylene filtration membrane constituting the polyethylene filtration layer is set to 0.
The thickness was 45 μm. The multilayer filter element E is made of PT
The FE filtration layer was arranged on the upstream side and the polyethylene filtration layer was arranged on the downstream side, and subjected to the test described above. (6) The test liquid, which is the fluid to be filtered, is prepared by dissolving a phenol resin in a thinner and having a viscosity of about 15 mPa · s (15 cP)
Was used. (7) In order to evaluate the filter life,
The test solution was filtered through a disc having a diameter of mm, and the amount of filtration was measured at regular intervals. Further, in order to evaluate the cleanliness of the test solution (filtrate) after filtration, the filtrate was filtered with a Nuclepore membrane having a pore size of 0.05 μm, and the amount of filtration was measured at regular intervals. (8) The test results of the filter life are shown in FIG. 1, and the cleanliness of the test liquid (filtrate) after filtration is shown in FIG. As shown in FIG. 1, the filter life of the multilayer filter element D was the most excellent for the filter life. In addition, as shown in FIG. 2, the cleanliness of the test liquid (filtrate) after the filtration was superior to that of the multilayer filter element A in which the multilayer filter element D had only the PTFE filtration layer. .

FIGS. 3 and 4 show an embodiment in which the multilayer filter element of the present invention is formed in the form of pleats 11. Filter medium 10 having laminated filter element
As shown in FIG. 4, the polyolefin filtration layer 12, the upstream support layer / drain layer 13, the downstream support layer / drain layer 14,
With the TFE filtration layer 15 superimposed and in close contact,
It is formed in the form of pleats 11. This filter medium 10
Is a core 20 made of a synthetic resin material, as shown in FIG.
Are arranged in a ring shape as a whole, the periphery thereof is held in shape by a cage 30, and an end cap is joined to the upper and lower ends of the filter medium 10 by heat fusion or the like. In FIG. 3, only the lower end cap 40 is shown, and the upper end cap is omitted. The upstream support layer / drainage layer 13 and the downstream support layer / drainage layer 14 support the polyolefin filtration layer 12 and the PTFE filtration layer 15 to secure a flow path, whereby adjacent filtration membranes are separated from each other. It prevents the filtration fluid from flowing due to close contact. In addition, although a filtration layer is comprised by several or single filtration media (filtration membrane or filtration layer), it is shown as a filtration layer in drawing.

[0022]

According to the present invention, by forming the PTFE filtration membranes having different filtration apertures into multiple layers, the particle removal efficiency can be improved and the filtration life can be extended.

PT having excellent performance in filtering solid components
Combining an FE filtration membrane and a polyolefin filtration membrane that excels in filtering gel-like components to form a laminated filter element, the solid component such as photoresist and the pore size of the most downstream filtration membrane for removing the solid components It is possible to provide a filter excellent in filtration effect in the field of filtration in which a gel component having a diameter smaller than that of the mixture is present.

[Brief description of the drawings]

FIG. 1 is a diagram showing test results of filtration life of laminated filter elements A to E.

FIG. 2 is a diagram showing test results of the cleanliness of filtrates of the multilayer filter elements A and D.

FIG. 3 is a perspective view including a partially cut-away portion of a filter element formed by forming a laminated filter element of the present invention into a pleated shape.

FIG. 4 is a partially enlarged exploded view of the pleated filter element shown in FIG. 3; A, B, C, D, E Multilayer filter element 10 Filter medium 11 Pleat 12 Polyolefin filtration layer 13 Upstream support layer / drainage layer 14 Downstream support layer / drainage layer 15 PTFE filtration layer 20 Core 30 Cage 40 Lower end cap

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Sakamoto 46, Kasumi-no-sato, Oji, Ami-cho, Ibaraki Japan Inside the Pall Corporation Tsukuba Plant (72) Inventor Shuichi Tsuzuki 46, Kasumi-no-sato 46, Ami-cho, Inashiki, Ibaraki Japan Pall Corporation Applied Research Laboratory F term (reference) 4D006 GA07 HA74 MA03 MA06 MA22 MC22X MC23 MC30X NA34 NA40 PA01 PB13 PB20 PB70 PC01 4D019 AA03 BA13 BB08 BB10 BD01 BD02 CA02

Claims (13)

[Claims] 1. A laminated filter element comprising a PTFE filtration layer and a polyolefin filtration layer laminated, wherein said PTFE filtration layer is constituted by laminating a plurality of PTFE filtration membranes, and said plurality of PTFE filtration membranes are provided. Among them, at least one pair of PTFE filtration membranes is made of PTFE
A laminated filter element having a different pore size for each filtration membrane. 2. The laminated filter element according to claim 1, wherein the PTFE filtration layer is disposed upstream with respect to the flow of the fluid to be filtered, and the polyolefin layer is disposed downstream with respect to the flow of the fluid to be filtered. Of the at least one pair of PTFE filtration membranes, the P
Disposing the TFE filtration membrane on the upstream side, and disposing the PTFE filtration membrane having a smaller pore diameter on the downstream side,
The laminated filter element, wherein a solid component in the fluid to be filtered is separated by the E filtration layer, and a gel component in the fluid to be filtered is separated by the polyolefin filtration layer. 3. The multilayer filter element according to claim 2, wherein the pore size of the polyolefin filtration layer is greater than or equal to the pore size of the filtration membrane on the most downstream side of the PTFE filtration layer. Filter element. 4. The laminated filter element according to claim 1, wherein the polyolefin filtration layer is formed of the PTF.
The stacked type, which is disposed between the E filtration layers and configured such that the pore diameters of the two filtration layers decrease continuously or stepwise from upstream to downstream with respect to the flow of the fluid to be filtered. Filter element. 5. The multilayer filter element according to claim 1, wherein the PTF comprises:
The laminated filter element, wherein the E filtration layer is configured by laminating a pair of PTFE filtration membranes, and the polyolefin filtration layer is configured by a single polyolefin filtration membrane. 6. The multilayer filter element according to claim 3, wherein the upstream PTFE filtration membrane of the pair of PTFE filtration membranes has a pore size of 0.45 to 10 μm.
And the pore size of the PTFE filtration membrane on the downstream side is 0.05
And the pore size of the polyolefin filtration membrane is 0.1 to 1.0 μm. 7. The multilayer filter element according to claim 1, wherein the PTF comprises:
The multilayer filter element, wherein the E filtration layer and the polyolefin filtration layer are formed in a pleated shape while being overlapped with each other, and the multilayer filter element has a cylindrical shape as a whole. 8. A method in which a plurality of PTFE filtration membranes are laminated to form a PT
A laminated filter element comprising a FE filtration layer, wherein at least a pair of PTFE filtration membranes among the plurality of PTFE filtration membranes have different pore sizes for each PTFE filtration membrane. 9. The multilayer filter element according to claim 8, wherein, among the at least one pair of PTFE filtration membranes, the PTFE filtration membrane having a larger pore diameter is arranged on the upstream side with respect to the flow of the fluid to be filtered. The laminated filter element, wherein the smaller PTFE filtration membrane is disposed downstream with respect to the flow of the fluid to be filtered. 10. The multilayer filter element according to claim 8, wherein the PTFE filtration layer is formed in a pleated shape, and the multilayer filter element has a cylindrical shape as a whole. Stacked filter element. 11. A laminated type wherein a plurality of polyolefin filtration membranes are laminated to form a polyolefin filtration layer, and at least one pair of polyolefin filtration membranes among the plurality of polyolefin filtration membranes has different holes for each polyolefin filtration membrane. Filter element. 12. The multilayer filter element according to claim 11, wherein, of the at least one pair of polyolefin filtration membranes, the polyolefin filtration membrane having a larger pore diameter is disposed upstream with respect to the flow of the fluid to be filtered. The multilayer filter element, wherein the polyolefin filtration membrane having a smaller size is disposed downstream with respect to the flow of the fluid to be filtered. 13. The multilayer filter element according to claim 11, wherein the polyolefin filtration layer is formed into a pleated curve, and the multilayer filter element has a cylindrical shape as a whole. Stacked filter element.