JPH0545448Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a filter for polymers used in the production of films and fibers such as polyester and polyamide.

[Conventional technology]

When extruding molten polymer through a die or die to produce fibers or films, removing foreign matter, gel, etc. from the polymer is an extremely important issue in terms of product quality, and various filters have been developed and used in the past. . As one example, a leaf filter 1 shown in FIG. 4 is known.
This leaf filter 1 consists of a pair of disk-shaped filter media 2 made of sintered metal fibers, whose outer peripheries are fixed, for example, by welding, and a coarse wire mesh 3 serving as a spacer for forming voids inside. and perforated plates 4, 4 for supporting filter media are arranged, and a hub ring 5 is attached to the center. Such leaf filters 1 are stacked using a central hub ring 5 around a polymer discharge pipe (not shown) having a polymer introduction hole on its outer circumferential surface to form a filter unit. The polymer to be filtered enters the gap 6 in the leaf filter 1 from the outside of the leaf filter 1 through the filter media 2, 2, flows radially inward in the gap 6 formed by the wire mesh 3, and passes through the hub ring. 5 to the polymer discharge pipe. Here, as the wire mesh 3 for forming the void 6, 8 mesh wire mesh (wire diameter 1.2 mm) is usually rolled and flattened to a thickness of about 2 mm.

[Problem that the invention attempts to solve]

However, such leaf filters for polymers have the problem of requiring high filtration pressure.

The present invention was devised in view of these problems, and an object of the present invention is to provide a polymer filter with low passage resistance.

[Means for solving problems]

The passage resistance in the leaf filter is (a) filtration resistance of the filter medium 2 itself, (b) resistance when the polymer passes through the hub ring,
(c) The resistance of the polymer that passes through the filter medium 2, passes through the perforated plate 4, flows laterally through the wire mesh 3, and reaches the hub ring. Conventionally, among these, (a) and (b) It was thought that there would be a lot of resistance. However, when the present inventors confirmed these passing resistances through experiments, they found that the ratio of the above (a), (b), and (c) was 1 to 2:2 to 3:7.
It was found that the resistance due to the wire mesh 3 was extremely large. The reason for this is thought to be that, as shown in Fig. 5, in the wire mesh 3, the passage of the horizontal wire 3a is blocked by the vertical wire 3b, resulting in a small opening ratio (for example, about 20%). . Therefore, reducing the resistance in (c) is effective in reducing the resistance of the leaf filter as a whole.

The present invention was made based on this knowledge, and includes a polymer filter in which a spacer is interposed between a pair of disc-shaped filter media. It is characterized by being configured with the following features.

〔Example〕

Embodiments of the present invention shown in FIGS. 1 to 3 will be described below. In FIG. 1, a leaf filter 1 according to an embodiment of the present invention, like the conventional leaf filter shown in FIG. 4, includes a pair of disc-shaped filter media 2, 2 made of sintered metal fibers, It has porous plates 4, 4 for supporting filter media arranged inside thereof, and a hub ring 5 at the center. However, between the perforated plates 4, a spacer 8 having a special structure is arranged, unlike a conventional wire mesh.

The spacer 8 used in the present invention is constructed by winding a wire 9 in a spiral shape into a plate shape, as shown in a part of the plane in FIG. It is curved into small waves. When winding the wire 9 in a spiral, the peaks and valleys of adjacent wires do not need to match and may be randomly shifted. Furthermore, adjacent wires may be in contact with each other, or may be spaced apart at appropriate intervals. When the wires are wound so that they touch each other, the passing resistance increases slightly compared to when they are spaced apart, but the wire density increases, and therefore the apex 9a of the wire that supports the upper and lower perforated plates 4, 4 increases. The number of holes increases, and the supporting strength of the perforated plates 4, 4 increases. Furthermore, since the perforated plates 4, 4 are supported at many points, deformation (transfer) of the perforated plates 4, 4 and the filter media 2, 2 thereon can be effectively prevented when filtration pressure is applied. The winding density of the wire may be determined by taking these points into consideration. In addition, when forming a spacer by winding wires in a spiral shape while contacting each other, adjacent wires may be fixed by sintering or the like. In that case, the advantage is that the compressive strength is further increased.

The polymer leaf filter 1 having the above structure is also used in the same way as conventional leaf filters, and the filter media 2, 2
The polymer entering the interior through the spacer flows radially inwardly through the spacer 8 and is removed from the central hub ring 5. At this time, in the spacer 8 having the above configuration, the space 9b of the wave-curved wire 9 (see FIG. 3) forms a passage for the polymer, but unlike a wire mesh, no wire is inserted into this space 9b. Therefore, the aperture ratio increases considerably. Therefore, the resistance to polymer passage is reduced compared to a wire mesh, and the filtration pressure can be lowered compared to a conventional leaf filter using a wire mesh.

In the above embodiment, a sintered body of metal fibers was used as the pair of filter media 2, 2, but other types of filter media may be used, for example, a sintered body of metal powder may be used. good. When a filter medium that is rigid itself, such as a sintered body of metal powder, is used, the perforated plates 4, 4 may be omitted, and the filter medium may be directly supported by the spacer 8. A sintered metal plate may be used instead of the perforated plate 4 interposed between the filter medium 2 and the spacer 8.

Further, in the above embodiment, the present invention is applied to a leaf filter that has an integral structure in which the outer peripheries of the pair of filter media 2, 2 are fixed to each other, but the present invention is not limited to this type of leaf filter. It is also applicable to a filter in which a pair of filter media 2, 2 are not fixed to each other but simply stacked with spacers interposed therebetween.

[Effect of idea]

As explained above, the present invention uses a spirally wound wire curved into small waves as the spacer placed between the pair of filter media 2, 2, so that the polymer that passes through the spacer This has the effect that the resistance of the filter can be reduced, and the passage resistance of the entire filter can be reduced. Moreover, since the spacer used here is made of wire, it can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention;
FIG. 2 is a plan view of the spacer used in this example.
Figure 3 is a side view of the wire constituting the spacer;
The figure is a schematic sectional view of a conventional leaf filter, and FIG. 5 is an enlarged sectional view of a part of a wire mesh used in the leaf filter. 1... leaf filter, 2... filter medium, 3... wire mesh, 4... porous plate, 5... hub ring, 6... void, 8... spacer, 9... wire.

Claims (1)

[Scope of utility model registration request] A polymer filter comprising a spacer interposed between a pair of disc-shaped filter media, characterized in that the spacer is formed by spirally winding a wire curved into small waves.