JPH1099610A - Leaf filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the pressure-resistant strength of a hub ring part to enhance the flowability of the polymer flowing in the hub ring part to make the polymer easy to discharge and to prevent the stagnation of the polymer to reduce the generation of a gelled polymer. SOLUTION: Plate-shaped filter materials 2 formed by sintering metal fibers are arranged to both surfaces 4 of a spacer through perforated support plates 3 and the perforated support plates 3 and the plate-shaped filter materials 2 are fixed to the outer peripheral part of a hub ring 5 having a plurality of guide holes bored therein so as to allow the outer and inner peripheral surfaces thereof to communicate with each other and the outer peripheral part of the hub ring 5 is formed so as to have a protruding structure thinner than the inner peripheral part thereof and the inner peripheral surfaces of the spacer and the perforated support plates are arranged so as to come into contact with the protruding outer peripheral surfaces of the hub ring or to be superposed on a part of the protruding outer peripheral surfaces and the inner peripheral surfaces of the perforated support plates 3 and the protruding outer peripheral surfaces or the inner peripheral parts of the perforated support plates 3 and the protruding outer peripheral surfaces are integrally welded and the inner peripheral parts of the metal fiber sintered filter materials are superposed on the protruding outer peripheral surfaces and the inner peripheral parts of the filter materials are caulked so that no difference in level is generated between the protruding outer peripheral surfaces and the outer surfaces of the filtrate contact part of the hub ring 5 and the inner peripheral parts of the filter materials and the outer peripheral part of the hub ring 5 are integrally welded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to leaf filters, and more particularly to polymer liquids, especially polyesters,
The present invention relates to a leaf disk filter of a sintered metal fiber filter medium suitable for filtering a molten polymer such as polycarbonate.

[0002]

2. Description of the Related Art When a thermoplastic polymer such as polyester or polycarbonate is melted and extruded to produce a film, it is usually necessary to remove coarse particles due to foreign substances and fillers in the polymer before extruding, or to form a large gel-like material. Filtration of the molten polymer is carried out in order to remove. As this filter, a so-called leaf disk type filter (filtration device) is used in which a large number of filter media obtained by sintering metal particles or metal fibers processed into a leaf disk shape and having a large filtration area are provided. The filter material of this filter is made of metal fiber sintered body, which has higher porosity and lower filtration resistance than metal particle sintered body, so it is especially suitable for microfiltration of high viscosity polymer. Te

The above-mentioned gel-like substance is a thermal degradation product of a polymer, and is often generated in a step of melting and transferring a polymer by an extruder, but may be generated in a filtration step. In a conventional sintered metal fiber filter, particularly, a portion around the hub ring around the inner periphery of the filter medium has a structure in which the polymer tends to stay, and the polymer staying in this portion often changes into a gel-like material.

The structure near the inner periphery of a filter medium of a conventional type metal fiber sintered filter has a structure as shown in, for example, an enlarged sectional view of a main part of FIG. This figure is also a partially enlarged view when a filter is stacked and used as a filtration device. As shown in FIG. 4, the inner peripheral portion 21 of the filter medium is squeezed and formed into a so-called solidified state.
Numeral 2 is welded 25 to the ridge 24 of the protrusion 23 on the outer periphery of the hub ring, and a groove 26 is formed concentrically in contact with the ridge. In the filter, filters of the same shape are stacked in multiple stages at a fixed gap 28 via a spacer 27. The molten polymer that has flowed into the housing (not shown) is diverted to the gap 28 of the multi-layered filter,
Most of the gas passes through the spacer inside the filter through the filter medium and the porous support plate, and is discharged from the guide hole of the hub ring.
(Bag alley) and stays.

[0005] The welding of a porous filter medium and a bulk metal is generally performed by plasma welding. In this case, when the welded portion is heated, the bulk portion has a large heat capacity and the heat diffusion is rapid, while the porous portion has a heat capacity. Since the diffusion rate is small and slow, a difference in the rate of temperature rise and dissolution rate occurs between the two, making uniform welding difficult. This problem is small because the porosity is small when the filter medium is made of a sintered metal particle, but the porosity is much larger when the filter medium is made of a sintered metal fiber, and the fiber diameter of the constituent fibers is much smaller than the particle size. Therefore, a device was required to weld the fiber sintered body. As a contrivance, for example, as in the structure shown in FIG. 4, the periphery of the welded end surface of the fiber sintered body is concentrically pressed and solidified to reduce the porosity, and it differs depending on the welding means and conditions. In order to slow the thermal diffusion of the bulk portion, a groove for heat insulation is formed parallel to the welding surface.

[0006] In such a type of filter, the fiber sintered body in contact with the welding surface is reduced in thickness for solidification.
There is a problem that the volume of the closed space between the filter and the opposing filter is increased. This solidified part has a considerably low porosity and extremely high resistance to fluid passage,
Since the flow of the polymer is slow, the polymer that has flowed into the closed space around the hub ring is difficult to be discharged. In particular, the polymer that has entered the groove is difficult to flow, and tends to stay and cause a gelled polymer.

As a method for increasing the flowability of a polymer in a closed space around a hub ring, Japanese Utility Model Application Laid-Open No. 6-41810 has been proposed.
No. proposes a structure in which an outer ring is attached to the outside of the inner periphery of the filter medium and the inner periphery of the outer ring and the inner periphery of the filter medium are fixed by welding so as not to leak liquid. Is not sufficiently high, it may be difficult to ensure the seal between the filters when stacking many filters.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem, to provide a hub ring with a high pressure resistance and to reduce or eliminate a closed space around the hub ring and a groove on the outer peripheral surface of the hub ring. An object of the present invention is to provide a leaf filter that enhances the fluidity of a polymer that has flowed into a container, makes it easier to be discharged, and reduces the generation of a gelled polymer due to stagnation.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
According to the present invention, a plate-shaped filter medium obtained by sintering metal fibers on both surfaces of a spacer via a porous support plate is arranged, and the porous support plate and the plate-shaped filter medium are connected to an inner peripheral surface from an outer peripheral surface. A leaf filter fixed to an outer peripheral portion of a hub ring provided with a guide hole, wherein the outer peripheral portion of the hub ring has a projecting structure thinner than an inner peripheral portion, and the inner peripheral surface of the spacer has the projecting outer peripheral surface. Or the inner peripheral portion thereof is disposed so as to overlap with a part of the protruding outer surface, and the porous support plate is arranged such that its inner peripheral surface is in contact with the protruding outer peripheral surface or its inner peripheral portion. Are arranged so as to overlap a part of the projecting outer surface, and the inner peripheral surface of the porous support plate and the projecting outer peripheral surface or the inner peripheral portion of the porous supporting plate and the projecting outer surface. And the metal fiber sintered filter medium overlaps the inner peripheral portion thereof with the protruding outer surface to form the filter medium. The inner peripheral portion is caulked such that there is substantially no step between the outer surface and the outer surface of the filtrate contact portion of the hub ring, and the inner peripheral portion of the filter medium and the outer peripheral portion of the hub ring are welded and integrated. Achieved by a leaf filter.

The leaf filter has a depth of 1 mm or more on an outer surface of the outer peripheral portion of the hub ring which is in contact with the filtrate.
Furthermore, it is preferable that there is no ring-shaped groove or concave portion of 0.8 mm or more, particularly 0.6 mm or more, and the distance between the outer periphery of the seal between the filters and the outer periphery of the hub ring is 1 to 5 mm, further 1 to 4 mm. It is preferred that

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a leaf filter showing one embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part thereof, which is also a partially enlarged view when the filters are stacked and used as a filtering device. FIG. 3 is an enlarged sectional view of a main part of a filter according to an embodiment different from that of FIG.

Referring to FIGS. 1 and 2, a leaf filter 1 is shown.
Has a pair of metal fiber sintered filter media 2 having a circular opening in the center and having their outer peripheries fixed to each other by welding, and a perforated plate 3 supporting the filter media. Are arranged on both sides of a spacer 4 which forms a space for passing the filter medium, and the inner peripheral openings of the filter medium 2 and the perforated plate 3 are fixed to the outer peripheral part of the hub ring 5. The hub ring 5 is provided with a plurality of conducting holes extending from the outer peripheral surface 6 to the inner peripheral surface 7, and the outer peripheral portion of the hub ring has a projecting structure thinner than the inner peripheral portion. Further, the outer surface 8 of the protruding structure may be stepless, or may be stepwise thinned or gradually thinned except for the welding side surface 9. Among them, a step-like structure is preferable. FIG. 3 shows a structure in which this stepped structure is different from that in FIG. 2, in which the inner peripheral opening of the perforated plate 3 is overlapped and fixed to a part (tip) 13 of the protruding structure of the hub ring 5.

In the present invention, the spacer 4 is arranged such that its inner peripheral surface is in contact with the outer peripheral surface 6 of the protruding structure or its inner peripheral portion overlaps a part of the outer surface of the protruding structure. Further, as described above, the porous support plate 3 is disposed such that its inner peripheral surface is in contact with the outer peripheral surface 6 of the protruding structure or its inner peripheral portion overlaps a part of the outer surface of the protruding structure. And is welded and integrated at the contact portion 10.

The metal fiber sintered filter medium 2 overlaps the inner peripheral portion thereof with the outer surface 8 of the protruding structure, and the inner peripheral portion of the filter material 2 is disposed so as to be in contact with the welding side surface 9 of the hub ring. The inner periphery of the filter medium is concentric with the width of 1 to 5 m so that there is substantially no step between the outer surface 12 and the outer surface 11 of the filtrate contact portion of the hub ring.
m is compressed and solidified, and the inner peripheral portion of the filter medium and the outer peripheral portion of the hub ring are welded and integrated. Since the metal fiber sintered filter medium has a groove in the melted part of the filter medium even if it is pressed and solidified,
It is desirable to optimize the solidification conditions and the peripheral shape of the welding side surface of the hub ring so as to minimize the groove in the fusion zone.

For welding the filter medium 2 and the hub ring 5, it is preferable to use a method of welding at a high energy density.
For example, by using a laser welding method that can greatly increase the energy density per unit area, the temperature rise rate of the irradiated part is fast, and the depth and width of the groove of the hub ring can be made significantly smaller than in the case of plasma welding. Good welding is possible without forming a groove depending on the shape of the welded body and welding conditions.

By taking such measures, it is possible to manufacture a leaf filter having no or very small ring-shaped grooves or recesses on the outer peripheral surface of the hub ring in contact with the filtrate on the outer surface. The leaf filter of the present invention has a depth of 1 m.
It is preferable that the leaf filter has no ring-shaped groove or recess having a length of at least m, more preferably at least 0.8 mm, particularly at least 0.6 mm. The distance between the outer periphery of the seal between filters and the outer periphery of the hub ring is preferably 1 to 5 mm, more preferably 1 to 4 mm.

[0017]

According to the filter of the present invention, for example, fifty filters shown in FIG. 2 are passed through a filter shaft and stacked to form a polymer filtration device, which is used at 310 ° C.
When the polyethylene-2,6-naphthalate heated to a temperature of about 2 mm is filtered and extruded into a sheet, the time required for the polymer gel to be contained in the sheet is 3 hours as compared with the conventional filter shown in FIG. More than doubled.

Therefore, according to the present invention, the pressure resistance of the hub ring portion is high, the closed space around the hub ring and the groove on the outer peripheral surface of the hub ring are eliminated or reduced, and the fluidity of the polymer flowing into the portion is enhanced. It is possible to provide a filter that can be easily discharged and that prevents stagnation and reduces generation of a gelling polymer.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a leaf filter according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged sectional view of a main part of a leaf filter according to one embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a conventional type metal fiber sintered filter.

[Explanation of symbols]

 1. Leaf filter 2. 2. Metal fiber sintered filter material 3. Perforated support plate Spacer 5. Hub ring 26. Groove

Claims (3)

[Claims] 1. A plate-like filter medium obtained by sintering metal fibers on both sides of a spacer via a porous support plate, and a plurality of conductors passing the porous support plate and the plate-like filter medium from the outer peripheral surface to the inner peripheral surface. A leaf filter fixed to an outer peripheral portion of a hub ring having a hole, wherein the outer peripheral portion of the hub ring has a projecting structure thinner than an inner peripheral portion, and the inner peripheral surface of the spacer is formed on the outer peripheral surface of the projecting shape. Arranged so that it touches or its inner peripheral part overlaps a part of the protruding outer surface, and the porous support plate has its inner peripheral surface in contact with the protruding outer peripheral surface or its inner peripheral part Arranged so as to overlap a part of the projecting outer surface, and the inner peripheral surface of the porous support plate and the projecting outer peripheral surface or the inner peripheral portion of the porous supporting plate and the projecting outer surface. The metal fiber sintered filter medium is overlapped with the inner peripheral portion and the protruding outer surface, and the inside of the filter medium is welded. The peripheral portion is caulked so that there is substantially no step between the outer surface and the outer surface of the filtrate contact portion of the hub ring, and the inner peripheral portion of the filter medium and the outer peripheral portion of the hub ring are welded and integrated. Leaf filter. 2. The leaf filter according to claim 1, wherein the outer peripheral surface of the hub ring in contact with the filtrate has no ring-shaped groove or recess having a depth of 1 mm or more. 3. The leaf filter according to claim 1, wherein the distance between the outer periphery of the seal between filters and the outer periphery of the hub ring is 1 to 5 mm.