JPH0731116U - Laminated filter media - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the fluid to be treated from staying just below the protective screen and to improve the bond strength of each layer. [PROBLEMS] A protective screen having a sheet shape woven by intersecting wire rods, and having a flattened portion in which the wire rods are flattened at the intersecting portions of the wire rods formed on at least one surface, and dispersed on the one surface of the protective screen. A filter medium layer using fine elements is integrally bonded through a layer, and the average pore diameter of the dispersion layer is larger than the average pore diameter of the filter medium layer, and the thickness thereof is the width of the flat portion of the protective screen. A laminated filter medium characterized by being 0.3 to 5 times W.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a laminated filter medium capable of preventing retention of a fluid to be treated by a protective screen and improving the bond strength of each layer.

[0002]

[Prior art]

 For example, the filter material used for the filtration treatment for removing and separating fine particles in the liquid has been developed to have a material and a form corresponding to the physical properties of the fluid to be treated. Among them, for example, metal fibers and fine metal powders are sintered. Metal sintered bodies are widely used because of their many advantages such as heat resistance, corrosion resistance, mechanical strength, and workability.

As a filter medium using such a metal sintered body, the present applicant discloses, for example, in Japanese Utility Model Publication No. 59-176615, that at least one surface of a filter medium using fine metal such as metal fiber is protected. We propose a laminated filter medium that has a screen and is sintered and integrated.

Such a protective screen for a laminated filter medium is used for reinforcement of the filter medium and for protection of the filter medium for preventing changes in properties such as pore diameter due to lack of fibers in the filter medium during handling and the like. It

In particular, in recent years, in order to improve filtration accuracy and filtration efficiency, the filter medium is made as thin as possible to reduce the flow resistance, and in such a filter medium, a protective screen is indispensable.

[0006]

[Problems to be solved by the device]

 However, due to the recent demand for advanced filtration performance, a sintered body obtained by sintering fine fibers having a fiber diameter of several μm may be used as a filter medium. When such a filter material is used, the protective screen is usually a thin wire of about 0.1 to 0.5 mm from the viewpoint of not impairing the filtration characteristics, and the wire forming the meridian and the latitude line of the protective screen is thick. Due to the corrugation in the direction, the substantial joint surface between the filter medium and the protective screen when laminated is very small.

As a result, the two have poor bond strength, are easily peeled off during handling and post-processing, and cannot function as a protective screen. Further, such a tendency is increased by miniaturization and miniaturization of the constituent members of the filter medium as described above.

In order to solve these problems, it is conceivable that the protective screen and the filter medium are narrowed in order to combine the two with a larger joint area, and the filter medium is bitten into the protective screen to increase the joint area. The filter material is pressed and deformed just below the intersection of the wire of the screen, locally reducing the pore size and impairing the flow, causing retention and impairing the filtration characteristics.

In addition, it has been experimentally conducted to employ a reinforcing plate such as a protective screen or a punching plate whose both surfaces are pressed to be flat and to increase the contact area by increasing the contact area without deforming the filter medium. In such a reinforcing plate, the ratio of the non-opening portion to the total area is considerably large, for example, about 40 to 50%. As a result, in the laminated filter medium in which the reinforcing plate and the filter material having fine pores are simply laminated, The fluid to be treated cannot be completely flowed into the subordinates, and the substantial filtration treatment is restricted only to the openings, and therefore, the satisfactory filtration efficiency cannot be obtained.

Moreover, a retention phenomenon is likely to occur in the non-opening portion. For example, when the fluid to be treated is a highly viscous polymer or the like, gels due to polymer deterioration are generated and mixed together, which deteriorates product quality. is there.

The present invention solves the above-mentioned problems by using a protective screen and interposing a dispersion layer having a predetermined characteristic between the filter medium and the filter medium to form a laminate, which has excellent mechanical strength and filtration characteristics. The purpose is to provide a filter medium.

[0012]

[Means for Solving the Problems]

 The present invention provides a protective screen having a sheet-like shape in which wire rods are crossed and having a flattened portion formed by flattening the wire rods at the intersecting portions of the wire rods, at least on one side thereof. The filter medium layer using the fine elements is integrally bonded through the dispersion layer, and the average pore diameter of the dispersion layer is larger than the average pore diameter of the filter medium layer, and the thickness thereof is the flatness of the protective screen. The multilayer filter medium is characterized in that the width W of the part is 0.3 to 5 times.

[0013]

[Action]

 As described above, in the laminated filter medium of the present invention, the protective screen having the flat portion and the filter medium layer are bonded together through the dispersion layer having a predetermined thickness, and the dispersion layer has a larger pore diameter than the filter medium layer. By having it, the to-be-processed fluid can easily flow into the inside of the laminated filter medium.

Therefore, even if a large non-opening portion is formed on the protective screen, the fluid to be treated can easily enter directly under the protective screen and is almost even before reaching the downstream filter medium layer. Therefore, retention can be prevented by performing filtration by effectively utilizing the entire surface of the filter medium layer.

Moreover, the dispersion layer can relieve the filtration pressure acting on the filter medium layer, and also functions as a pre-filter layer for removing relatively large foreign matter by the dispersion layer, which can contribute to the improvement of the life of the laminated filter medium. .

Further, the flat portion formed at the intersection of the wire members of the protective screen increases the bonding surface area with the dispersion layer, and when the element of the dispersion layer has a larger diameter than the element of the filter material, the protective screen The bond strength with and is further increased, and the above-mentioned peeling due to insufficient bond is reduced.

[0017]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged perspective view showing an embodiment of the laminated filter medium 1 according to the present invention, and FIG. 2 is a sectional view showing another embodiment.

As shown in FIG. 1, the laminated filter medium 1 has, for example, a dispersion of pore diameters larger than that of the filter medium layer 3 between the protective screen 2 arranged on the upstream side and the filter medium layer 3 arranged on the downstream side. The layer 4 is arranged and is wholly sintered and integrated.

The protection screen 2 is in the form of a sheet formed by intersecting and weaving a wire rod 2 composed of a meridian line 2A and a latitude line 2B. In this example, the flattened protective screen 2 in which the wire 2 at the intersection 2C is deformed by pressing both sides of the sheet-like body and the flat portions 2D are provided on both sides is used. Further, the protective screen 2 may be one in which the flat portion 2D is formed only on the surface in contact with the dispersion layer 4 by, for example, grinding or polishing.

The wire 2 of the protective screen 2 is, for example, a 0.1 to 0.5 mm thin stainless steel wire, and a sheet-like woven body woven to about 10 to 100 # is preferable.

When the flat portion 2D is formed by, for example, pressing (rolling), the reduction rate (T) is set to 10 to 50%. In addition, the rolling reduction means the weaving thickness (T0-T1) with respect to the difference (T0-T1) between the woven thickness (T0) of the woven fabric and the thickness (T1) after pressing, as shown in the following equation. ) Ratio. Reduction ratio (T) = (T0-T1) / TO × 100

When the rolling reduction is 10% or less, a flat portion having a size necessary for increasing the bonding strength cannot be obtained and a high bonding strength cannot be obtained. On the other hand, in the case of a heavy working exceeding 50%, a meridian and a weft line are obtained. The area of the opening 5 between them decreases due to the widening of, and the flow-through area is substantially reduced. When pressed (rolled), the height of each flat portion 2D becomes uniform over the entire surface, and a flat portion having a desired thickness can be obtained. Especially when stainless steel is used, work hardening causes a strong screen. Become. In addition, since it is a woven body, it is less likely to expand and contract and deform, and has an excellent reinforcing effect. Further, even at the intersections of the wire rods, the wire rods are dented and deformed into each other so that the wire rods can be engaged with each other, resulting in a screen with no misalignment.

From this point of view, the rolling reduction T is 10 to 50%, preferably 20 to 50%, and more preferably 30 to 45%.

When the rolling reduction (T) is 10 to 50%, the width W of the flat portion 2D when the wire 2A and the parallel 2B have the same diameter and the same kind of circular cross section is used. It is about 0.3 to 1.1 times the diameter d before reduction. The width W of the flat portion 2D means the maximum dimension of the flat portion 2D in the direction perpendicular to the longitudinal direction of the longitude line 2A or the latitude line 2B.

The woven body is not only a plain weave but also one having other woven structures such as twill weave and tatami weave, in which, for example, pitch intervals are changed, wire rods having different thicknesses are used for meridians and wefts. Is also adopted. In the case of wires having different thicknesses, the flat width W is the maximum width described above.

On the other hand, the filter medium layer 3 substantially filters the fluid to be treated and guarantees the filtration performance. This filter medium layer 3 is composed of a single layer as shown in FIG. As shown in FIG. 2, a two-layer structure including a fine and thin first filter medium layer 3A on the most downstream side and a second filter medium layer 3B slightly rougher and thicker than the upstream first filter medium layer 3A, for example. It can also be a body.

Further, a multilayer structure may be used, and an increase in the number of layers generally improves the filtration efficiency. In the case of FIG. 2, the flat portion 2D is formed on the protective screen 2 by grinding only on one side (lower surface) side.

As the filter medium layer 3, for example, in addition to stainless steel, metal long fibers, metal short fibers, metal powders made of various metals or alloy materials such as nickel, chromium, aluminum and copper, or a mixture thereof is used. The sintered body of the fine elements is used.

When the liquid to be treated is a high-temperature and high-viscosity fluid such as a polymer, it is, for example, a stainless steel short fiber sintered body, and is disclosed in Japanese Examined Patent Publication Nos. 63-5443 and 63-63645. The fine fiber diameter disclosed in Japanese Patent Publication No. 63-31521 and the like, which uses a short fiber having an aspect ratio of about 2 to 15, can provide a sintered body having a fine and uniform and high porosity. Therefore, it can be preferably adopted. When a single filter layer 3 is used as shown in FIG. 1, its thickness is about 0.02 to 2 mm, usually 0.3 to 1.0 mm, and especially when it is intended to improve the filtration efficiency, for example, A membrane filter having a thickness of about 0.5 to 0.02 mm is used.

Even when the fluid to be processed is a polymer, if it is a high-quality polymer, for example, a polymer for a film (video film), it is necessary to completely remove even fine foreign matter, so that the filtration accuracy is first. In some cases, the pore diameter is set to 10 μm or less (preferably 5 μm or less), while the thickness and the porosity may be freely set.

When the two filtration layers 3 of FIG. 2 are used, the first filtration layer 3 A may be, for example, atomized powder particles having a particle size of 5 μm or less, or an average aspect ratio of 2 with a diameter of 0.1 to 20 μm. Sintered products using -50 metal short fibers or the like can be adopted. In particular, the sintered product using short metal fibers has three-dimensional pores, resulting in low pressure loss. A sintered product of a mixture of short metal fibers and powder particles can also be used.

Further, the use of the short fibers can reduce the variation in the pore diameter to make the thickness as thin as 10 to 500 μm, preferably 20 to 100 μm, and further reduce the pressure loss by thinning the thickness. .

The second filtration layer 3B has pores with a larger diameter than that of the filtration layer 3A, supports the first filtration layer 3A, and traps relatively large impurities prior to the filtration layer 3A. This extends the filtration life of the filtration layer 3A and suppresses an increase in pressure loss.

For this reason, the second filtration layer 3B preferably has a gradually increasing pore size toward the upstream side. Therefore, two or more layers having different fiber diameters or filtration diameters are sequentially laminated. It may be formed as a laminated body.

The second filtration layer 3B may be a sintered product such as metal particles, metal fibers, metal short fibers or a mixture thereof, as in the case of the first filtration layer 3A. The length is about 0.2 to 2 mm.

In order to integrally form such a thin first filtration layer 3 A having a minute pore size on the second filtration layer 3 B, the applicant has previously proposed Japanese Patent Application No. 3-289087. A method, that is, a method in which a suspension in which metal particles are suspended in advance is suction-adhered to one surface of the second filtration layer 3B 1 manufactured in advance with a predetermined thickness and then sintered can be used.

On the other hand, the dispersion layer 4 is in contact with the flat portion 2D of the protective screen 2 and has an average pore diameter larger than that of the filter medium layer 3 as described above to prevent clogging. The layer 4 is preferably a fiber nonwoven fabric made of metal fibers having a diameter of 2 to 50 μm, preferably about 15 to 50 μm, such as stainless steel fibers, nickel fibers, and Hastelloy fibers, and pressure-sintered to a predetermined thickness. Formed by. The average pore diameter can also be known by measuring the cross section with a microscope or the like.

The thickness of the dispersion layer 4 is 0.3 to 5 times the width W of the flat portion 2D formed on the protective screen 2, and is about 0.1 to 1.0 mm. If it is less than 0.3 times, a sufficient gap for uniform flow cannot be provided between the protective screen 2 and the filter medium layer 3, and the entire surface of the filter medium layer 3 cannot be effectively utilized. If it exceeds 5 times, the total thickness increases, and more preferably it is about 0.5 to 3 times.

In the case of FIG. 1, the dispersion layer 4 is made of a sintered body of stainless steel fibers and has a thickness of about 0.13 mm, like the filter medium layer 3, and the thickness thereof is the flat portion 2D. The width W is about 0.9 times. Further, as described above, the pore diameter is made larger than the pore diameter of the filter medium layer 3 on the downstream side by using the elements made of relatively thick metal fibers and by randomly distributing these elements.

The dispersion layer 4 made of such metal fibers has a porosity of about 50 to 80%, which is larger than that of the sintered body using powder, and is excellent in flexibility. Even if it is thin, there is no problem such as cracking, and it also functions as a buffer for filtration pressure. Further, by making the pore size larger than the pore size of the downstream filter medium layer 3, the flow of the liquid to be treated is improved and the problems such as retention are improved, except for filtration.

As a more preferable specific example of the dispersion layer 4, a 316L stainless fiber having a fiber diameter of 20 μm is pressed to have a porosity of 55% so that the pore diameter is about 17 μm. As shown in FIG. It is interposed between the flat surface 2D of the protection screen 2 and the filter medium 3 and is integrally coupled.

In order to use the laminated filter medium 1, the protective screen 2 is used as a single product with the upstream side being the upstream side, and a filter plate having, for example, a wire mesh or a sintered body as a supporting member is provided on the downstream side. It can also be 7. Further, as shown in FIG. 3, as a support member 9, a support plate 10 made of, for example, a punching plate, a screen 12 supported by the support plate 10, and a sintering layer 13 of metal fine particles such as short metal fibers and atomized powder. It is possible to use a combination of the laminated body 14 with. At this time, the screen 12 may have the same structure as that of the protection screen 2 described above.

The sintered layer 13 may be a filter medium layer 15 similar to the filter medium layer 3 and a fiber layer 16 similar to the dispersion layer 4.

The filter medium layer 15 can also be composed of first and second filter medium layers 15A and 15B having the same structure as the first and second filter medium layers 3A and 3B. The filter material layer 15A is arranged on the most upstream side.

With such a structure, it is possible to prevent pores from becoming coarse by changing from coarse to dense to coarse and to prevent abrupt changes in the flow velocity and to prevent retention, and for various filters such as leaf filters and tube filters. Can be adopted. Also, each member can be variously modified, for example, by mixing both at the boundary portion of each layer or forming an uneven shape.

(Specific Example) In order to evaluate the characteristics of the filter material of the present invention as a filter member, first, as shown in Table 1, the example product and the comparative example product 1 (the protective screen having no flat portion and the filter layer were directly attached to each other). Laminated and sintered ... No dispersion layer), Comparative product 2 (Protective screen having no flat portion bite into the filter medium layer to give a sufficient bonding area and sintered ... No dispersion layer), Comparative example product 3 (a filter screen laminated with a filter screen having a flat surface by pressing on both sides and then sintered ... No dispersion layer) was prepared.

In these laminated filter media, two filter plates 7, 7 each having a support member 9 shown in FIG. 3 superposed on each other are arranged so that the support plate 10 faces each other and a retainer mesh is arranged between them to form a leaf having an outer diameter of 300 mm. A filter was formed, and a leaf filter was set on a center post having a height of 100 mm to construct a filter device.

On the other hand, as a fluid to be treated, a polyethylene terephthalate polymer having a temperature of 300 ° C. was used, and the results of continuous filtration at a flow rate of 50 kg / h are also shown in Table 1.

[0049]

[Table 1]

In Table 1, the pressure loss means the pressure difference between before and after the filtration device, and the ease of washing means that after filtering polyethylene terephthalate, it is immersed in triethylene glycol and heat-treated to leave the polymer remaining in the filter. Judgment is made based on the length of time (the number of treatments) required to remove ash foreign matter by ultrasonic cleaning.

As is clear from Table 1 which is the result of measurement under the same conditions, the multilayer filter medium of the present invention has the longest gel generation time of 202 hours and also has a low pressure loss. It turns out that it is excellent. In addition, since the protective screen of the example product has a flat surface and the dispersion layer that can relatively increase the joint area is interposed between the protective screen and the filter medium layer, the bond between the two is strong and there is no problem such as peeling. Did not happen.

[0052]

[Effect of device]

 As described above, the laminated filter medium of the present invention has a diffusion layer provided between the protective screen and the filter medium layer to enhance the bonding strength between each part and the filtration efficiency. Can be used effectively.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing an embodiment of the laminated filter medium of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the laminated filter medium.

FIG. 3 is a perspective view illustrating an example of using a laminated filter medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated filter medium 2 Protective screen 2C Crossing section 2D Flat section 3 Filter medium layer 4 Dispersion layer

Claims (3)

[Scope of utility model registration request] 1. A sheet shape woven by intersecting wire rods,
In addition, a filter medium layer using fine elements is integrally formed on a protective screen having a flattened portion formed by flattening the wire rod at the intersecting portion of the wire rod on at least one side thereof, through a dispersion layer bonded to the one side of the protective screen. While being bonded, the average pore diameter of the dispersion layer is larger than the average pore diameter of the filter medium layer, and the thickness thereof is 0.3 to 5 times the width W of the flat portion of the protective screen. Laminated filter media to do. 2. The laminated filter medium according to claim 1, wherein the dispersion layer has a thickness in the range of 0.5 to 3 times the width W of the flat portion. 3. The reduction ratio of the protective screen is 10 to 50.
3. The laminated filter medium according to claim 1 or 2, wherein the flat portions are formed on both sides by pressing with%.