JPS6014902A - Filtration apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus having excellent removability of fine particles, filtration rate, chemical and heat resistances by using a porous membrane of polytetrafluoroethylene and a support of fluoroplastics having a specific shape, and making all parts of fluoroplastics. CONSTITUTION:A tubular filter body 8 is constituted by covering the outside of a tubular support of fluoroplastics with a tubular filtration membrane of polytetrafluoroethylene (PTFE) one end of which is closed, or inserting the filtration membrane into said support. And the tubular support 8 is arranged in a vessel of fluoroplastics which is constituted basically of outer vessels 5,6 and a supporting plate 7. A sheet-shaped porous PTFE made into a tubular form one end of which is closed is suitably used as the PTFE tubular filtration membrane. A porous molded tube obtained by sintering granular PTFE is suitable for the tubular support of fluoroplastics, since the molded tube is characteristically low in permeation resistance and difficult to deform.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a precision filtration device that has excellent chemical resistance and heat resistance and has all parts made of fluororesin.

(Background of the invention) Many filtration devices are known for separating fine particles contained in liquids and gases by precision filtration (very little is known about precision filtration devices with excellent chemical and heat resistance). Conventionally, even when using a fluororesin filtration membrane, other parts of the filtration device often use materials with poor chemical resistance and heat resistance, and the properties of these materials affect the overall performance. In addition, most sealing materials use rubber gaskets, which poses particular problems in terms of chemical resistance.Furthermore, the area of the filtration membrane per unit volume of the filtration device is small, making it difficult to filtrate. In many cases, it is difficult to obtain a large flow rate.

It is something to do.

(Structure of the invention) The configuration of the present invention will be explained in detail by including examples.

The polytetrafluoroethylene (hereinafter abbreviated as PTFE) tubular filtration membrane with one end closed in the present invention is suitably a sheet-shaped or tube-shaped PTFE porous membrane processed into a tubular shape with one end closed. Pore diameter is usually 0.01-10
It is selected from those with a diameter of 0 μm depending on the purpose. In particular, sheet-like or cheese-like P produced by the stretch sintering method
A TFE porous membrane in the form of a tube with one end closed is optimal. Basically, the method described in Japanese Patent Publication No. 18560/1983 is employed to produce a porous PTFE membrane by the stretch sintering method. The PTFE porous membrane produced by this method is characterized by having a microstructure consisting of fibers and nodules interconnected by the fibers, and has high mechanical strength and fine and uniform pore diameters. Since it is possible to manufacture membranes with large porosity, the filtration flow rate per unit area can be increased, making them optimal as filtration membranes.

It can be a tubular filtration membrane. Adhesion of PTFE porous membranes is done by overlapping the PTFE porous membranes and applying pressure.
This is achieved by heating the melting point of TFE (approximately 327° C.) or higher. Alternatively, a film or powder of another fluororesin is inserted between the stacked PTFE porous membranes, and the fluororesin is heated to a temperature higher than the melting point of the inserted fluororesin under pressure to inject the fluororesin into the pores of the PTFE porous membrane. This can also be achieved by infiltration. Examples of fluororesins used for this purpose include tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene rubber fluoroalkyl vinyl ether copolymer (P F
A), Tetrafluoroethylene-ethylene co-M combination (ETF E).

Polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVdF), polyvinyl fluoride (PV
F) It is suitable to use chlorotrifluoroethylene-ethylene copolymer or PFA.

A suitable fluororesin tubular support is a sintered porous tube of PTFE granules. This is a molded body with communicating holes that is manufactured by heating and sintering PTFE particles in a mold. This molded body is also suitably closed at one end as shown in FIG. 2A. Although those having a pore diameter of 0.1 μm to 1 mm are normally used, it is effective to select one having a pore diameter larger than that of the filtration membrane in order to lower the permeation resistance. This sintered porous molded tube has good permeability and is resistant to deformation, making it particularly useful as a support.

It is a laminate with layers made of perforated fluororesin tubes.

Here, the fluororesin net-like molded product or nonwoven fabric is used to increase the effective area of the transient membrane, and the pore diameter thereof is required to be larger than that of the transient membrane in order to lower the permeation resistance. The fluororesin reticulated molded product may be integrally molded into a reticulated material, or may be a woven or knitted material. Further, the perforated fluororesin tube usually has a structure as shown in Fig. 2B, in which a hole with a diameter of about 0.5 to 10 mm is made to serve as the ντ flow path of the fluororesin tube.

used. The shape of the hole is generally circular, but other shapes may be used. A fluororesin mesh molded product or nonwoven fabric is placed on the outer or inner surface of this perforated fluororesin tube. In the case of an external pressure type device that filters from the outside of the tube to the inside, a fluororesin mesh molded product or nonwoven fabric is placed on the outside of the perforated fluororesin tube (Fig. 2C), and the filter is filtered from the inside of the tube to the outside. In the case of an internal pressure type device, a fluororesin mesh molded product or nonwoven fabric is placed inside the perforated fluororesin tube.

Examples of the fluororesin that is the material for these tubular supports include PTFE, FEP, PFA, ETFE, and PC.
TFE, PVdF.

Examples include PVF and ECTFE. In particular, when heat resistance and chemical resistance are required, PTFE, FEP, PF
A etc. are valid.

In the case of an external pressure type device in which filtration is performed from the outside of the tube inward, the PTFE tubular filtration membrane is provided outside the fluororesin tubular support, whereas in the case of an internal pressure type device in which filtration is performed from the inside of the tube to the outside. In the case of the device, a PTFE tubular filtration membrane is mounted inside a fluororesin tubular support. The combination of this PTFE tubular filtration membrane and the fluororesin tubular support constitutes the tubular filtration body of the present invention. ’ can be mentioned. An arrangement example is shown in Fig. 3. In Fig. 3, the fluororesin container basically consists of outer containers 5 and 6 and a support plate 7, and the container A has the fluid inlet and outlet connected to one side of the container. The container B has an inlet and an outlet on both sides of the container. 8 is a tubular tube, the open end of which is fixedly sealed to the support plate 7;

In FIG. 3, when filtering from the outside to the inside of the tube, the inlet of the fluid is 9 and the outlet is 1o. On the other hand, inside the tube
When filtering from the - side to the outside, the fluid inlet will be 1o and the outlet will be 9. As an example of the support plate 70, a perforated circular plate as shown in FIG. 4 is generally used. As examples of methods for fixing and sealing the tubular filter body to the support plate, a method using a tapered screw, a method using heat fusion, or a combination of the two were suitable. Here, the thermal fusion includes a method of pressing with a jig heated to a temperature higher than the melting point of the resin, a method of using high-frequency induction heating, ultrasonic waves, and the like. Further, a connecting part made of fluororesin may be used for the connecting portion between the two. An example is shown in FIG. In FIG. 5, A is an example of a connecting part, and B is an example of a combination of a connecting part and a tubular support.

The tubular membrane could be end-sealed by heat-sealing its open end to a tubular support or connecting piece, or by inserting it into a locking thread. The closed end of the tubular filter body is located at the bottom of the container (
Fig. 3A) or a suitable support plate (Fig. 3B). In addition, a method of compressing the outer container from both sides by forming a fitting structure as shown in FIG. 6 was particularly effective. In order to compress from both sides, it was appropriate to place the fluororesin container inside a flanged metal or resin container and compress it. This method also has the advantage of increasing the pressure resistance of the container. In this case as well, since only the fluororesin container comes into contact with the fluid, the chemical resistance does not deteriorate at all.

The most excellent embodiment of the present invention will be described below.

First, the most suitable PTFE tubular filtration membrane was the one shown in FIG. 1A, in which a sheet-like PTFE porous membrane was formed into a tubular shape with one end closed. This sheet-shaped PTFE porous membrane is
From a PTFE porous membrane formed into a tube shape from the beginning,
This is because even when the pore size is uniform and the pore size is fine, the porosity can be increased and the membrane thickness can be reduced, resulting in a large filtration flow rate per unit area. The fluororesin tubular support is a sintered porous molded tube of PTFE particles (Figure 2A).
It was suitable because it had low permeation resistance and was not easily deformed. Particularly when used in external pressure type equipment, it was highly effective against pressure from the outside. If the structure is such that a PTFE tubular filtration membrane covers the outside of this support, the connecting parts shown in FIG. Connect as shown in Figure B, and then cover the outside with a PTFE tubular filtration membrane, and heat-seal the open end of the upper membrane to the connecting part.
A tubular-filter as shown in Figure C was preferred.

(Effect of the invention) The filtration device of the present invention uses PT, which is the most excellent precision filtration membrane.
This device uses a porous FE membrane and a fluororesin support of a specific shape, and all parts are made of fluororesin, so it has excellent performance in removing particulates from fluids, filtration flow rate, chemical resistance, and heat resistance. Therefore, it can be used for precision filtration of just about any fluid, and can efficiently treat corrosive or high-temperature fluids that have been difficult to filter in the past.

[Brief explanation of the drawing]

FIG. 2 is a diagram showing an example of a tubular filtration membrane manufactured from a porous PTFE membrane. FIG. 2A is a diagram showing an example of a sintered porous tube made of PTFE particles, and FIG. 2B is a diagram showing an example of a fluororesin perforated tube. C is a diagram showing an example of a tubular support having a structure in which a fluororesin network is arranged on the outside of a perforated fluororesin tube. FIG. 3 is a sectional view showing an example of a filtration device. FIG. 4 is a diagram showing an example of the support plate. FIG. 5A shows a connection part, B shows a combination of a connection part and a tubular support, and FIG. 5C shows an example of a PTFE tubular-membrane welded together. FIG. 6 is a diagram showing an example of a sealing method. l... PTFE tubular filtration membrane open end, 2... adhesive part,
8. Fluororesin perforated pipe, 4. Fluororesin net, 5.
6... Outer container, 7... Support plate, 8... Tubular filter body, 9.10... Inlet or outlet, 11... Sealing part, 12... Fusion part, 13... - PTFE tubular-transmembrane. ■1(2) Figure 72

Claims (1)

[Claims] (11) A tubular filtration body having a structure in which a polytetrafluoroethylene-shaped filtration membrane with one end closed covers the outside of a fluororesin tubular support or is inserted into the interior thereof, and has an inlet and an outlet for fluid. A filtration device characterized by being placed in a fluororesin container. (2) A polytetrafluoroethylene tubular filtration membrane of 0.0
The filtration device according to claim 1, having a pore diameter of 1 to 100 μm. (3) The filtration device according to claim 1, wherein the polytetrafluoroethylene tubular filtration membrane has a microstructure consisting of fibers and nodes interconnected by the fibers. (4) The filtration device according to claim 1, wherein the fluororesin tubular support is a sintered porous tube made of polytetrafluoroethylene particles. (5) The filtration device according to claim 4, wherein the sintered porous formed tube has a pore diameter of 0.1 μm to 1 mm. (6) a layer in which the fluororesin tubular support is made of a fluororesin net-shaped molded product or nonwoven fabric having a pore diameter larger than that of the filtration membrane;
Claim 1, characterized in that it is a laminate with a layer made of a perforated fluororesin tube, and the layer made of the fluororesin reticular molded product or the nonwoven fabric 4 is arranged on the filtration membrane side. filtration device. (7) The filtration device according to claim 1, wherein the fluororesin tubular support has a shape with one end closed. A filtration device according to claim 1, characterized in that: