JP7565765B2 - Method for forming dust-collecting layer on porous body without using binder - Google Patents

Description

The present invention relates to a technique for forming a dust-trapping layer on the surface of a dust-collecting filter without using a binder.
Specifically, the present invention relates to a method for manufacturing a filter that has low pressure loss and good energy efficiency, by forming a dust collection layer on the surface of a filter element material with a lamellar structure formed by sintering a resin, irradiating the fine particles that make up the dust collection layer with infrared rays to fuse them together, thereby forming a dust collection layer that has a certain degree of strength while providing high collection performance without using a binder.

The filter element of a dust collection filter is composed of a filter element material made of a resin sintered body and a dust collection layer made of fine resin particles. Depending on the specifications of the filter element, a conductive carbon layer may be added to the filter element.

The filter element material can be obtained by sintering synthetic resin powder using methods such as those described in Patent Documents 1 and 2, and the resulting sintered synthetic resin has gaps between the individual synthetic resin particles that make up the synthetic resin. The gaps allow air to pass through.

The dust collection layer of the dust collection filter element is formed by suspending the resin fine particles to be used as the dust collection layer in an aqueous solvent to prepare a coating liquid containing the resin fine particles to be used as the dust collection layer, applying the coating liquid to the surface of the filter element material made of a resin sintered body, and then drying the coating liquid.

In addition, in antistatic filter elements, conductive carbon powder is suspended in a water-based solvent to prepare a coating liquid containing the conductive carbon powder, and the carbon coating liquid is applied to the surface of the filter element material made of a resin sintered body and then dried to form a conductive carbon layer. After that, a coating liquid containing resin fine particles to be used as a dust collection layer is applied and then dried to form a dust collection layer.

The resin material and particle size of the fine resin particles used as the dust collection layer are selected according to the properties and particle size of the dust to be collected using the dust collection filter. The resin material used as the dust collection layer is selected from polyethylene (PE), polytetrafluoroethylene (PTFE), etc., and the resin particle size is selected from the range of 1 to 100 μm.

The dust collection layer is formed by individually stacking fine resin particles used in the collection layer, and has a structure in which there are gaps between the individual resin particles that make up the collection layer through which air can pass. Dust in the dust-laden air containing the particles to be collected is captured by the dust collection layer, and clean air after the dust is collected by the dust collection layer passes through the gaps formed in the collection layer through which air can pass and the gaps in the filter element material, and flows into the inside of the filter element.

Here, the structure of a general dust collector will be described with reference to FIG.
The dust collector 10 has a sealed casing 12, the interior of which is divided into a lower dust collection chamber 16 and an upper clean air chamber 18 by an upper top plate 14 which serves as a partition wall, and a dust-laden air supply port 20 which communicates with the lower dust collection chamber is provided halfway up the casing. A clean air outlet 22 which communicates with the clean air chamber is provided at the top of the casing. Furthermore, hollow, flat filter elements 24 are attached at predetermined intervals to the underside of the upper top plate, and a hopper 26 for discharging the removed dust and an outlet 28 for the dust are provided at the bottom of the casing.

As shown in FIG. 1 (2), the filter element 24 has a large diameter portion 32 at the upper end, which is formed into a bulging shape to accommodate a frame 34. Both ends of the frame housed in the large diameter portion are attached to the upper top plate 14 integrally with the large diameter portion via tightening bolts 36. A packing 38 is interposed between the upper top plate and the frame.

As shown in the perspective view (Figure 1 (3)) of the P-P cross section of the filter element's external view, the inside of the filter element has multiple hollow chambers 24a with open upper ends, and the dust-adhering surface of the element is corrugated or bellows-shaped to increase the adhesion area. Dust-laden air supplied from the dust-laden air supply port 20 into the dust collection chamber 16 of the casing passes through the filter body of the hollow filter element and flows inside. At this time, dust adheres to and accumulates on the surface of the filter element and is captured, and the clean air that flows inside the filter element passes through the passage of the frame and enters the clean air chamber 18 at the top of the casing, and is led to a specified location from its exhaust port 22.

When dust adheres to and accumulates on the surface of the filter elements, the air passages become blocked and pressure loss increases, so the filter elements 24 are backwashed in sequence at regular time intervals to remove the dust that has adhered to and accumulated on the surface of the filter elements. That is, the backwash valves (not shown) are opened and closed in sequence at regular intervals using timer control or the like, and pulsed air for backwashing is sprayed from each corresponding spray pipe. As a result, the pulsed air flows back from the inside to the outside of each filter element 24, and the dust that has adhered to and accumulated on the filter element surface is brushed off in the accumulated state without scattering. The dust that has been brushed off in this way is collected from the removal port 28 via the hopper 26.

The synergistic effect of the above-mentioned dust collector device configuration, the process of removing dust from dust-laden air, and the filter element configuration makes it possible for the filter element material made of a resin sintered body and the dust collection layer made of resin fine particles to be used continuously for long periods of time. As a dust collection filter element, it has been widely adopted as an environmental dust collection method for dust-generating locations in mines, quarries, steelworks, etc., both in Japan and overseas.

However, the dust collection layer formed by applying a conventional coating liquid to the surface of the filter element material is adhered to the surface of the filter element material by the adhesive force of the water-soluble binder, and therefore is not very strong. There was concern that when the dust powder that has adhered to and accumulated on the surface of the filter element is removed by pulsed air injection, part of the dust collection layer may peel off, causing contamination of the collected dust. For this reason, it could not be used in applications where prevention of contamination of food, etc. is important.

In recent years, there have been concerns about the impact of microplastics on marine life and the human body, and the ground is being conditioned to require contamination prevention even in general air filters.

Furthermore, compared to typical bag-type dust collection filters, the pressure loss (initial pressure loss) per filtration area at the start of operation is somewhat large, and this does not meet the needs of users who want to reduce initial costs. Given this background, there is a demand for the development of a dust collection layer that is stronger and has lower initial pressure loss, to be formed on the surface of the filter element material made of sintered resin.

Sintering is known as a method for firmly adhering resin particles, but when forming a dust collection layer on one side of a filter element material formed by sintering resin, the sintering method cannot be applied. This is because heat is applied from the filter surface toward the inside, which inevitably causes the filter to warp or distort.

In addition, the formation of the dust-collecting layer by preparing a coating liquid involved a process in which the coating liquid was applied to the surface of the filter element material and then dried. This required not only a robot with a complex mechanism for coating the surface of the filter element material, a dryer for drying the dust-collecting layer after coating, and waste liquid treatment equipment for the coating liquid, but also a lot of labor, manpower, and production time to produce the filter element.

JP 2003-126627 A JP 2004-202326 A

The object of the present invention is to provide a method for manufacturing a filter element in which a dust collection layer is formed on the surface of a filter element material made of a resin sintered body, and which does not cause warping or distortion in the filter, and which has a stronger filter element with a lower initial pressure loss.

In view of the problems of the above-mentioned conventional technology, the inventors further conducted trial and error to determine a method for forming a dust-collecting layer. As a result, they discovered that the filter would not warp or distort if the dust-collecting layer formed on one side of the filter material is heated by a heating means that irradiates heat rays and also heats the back side of the filter material, or the entire filter material on which the dust-collecting layer is formed is heated by a heating means that heats the filter material in a high-temperature atmosphere such as an oven, and further, if a resin powder with a lower softening point than the resin that constitutes the filter material or a resin powder with a smaller particle size than the resin that constitutes the filter material is used and sintered in an appropriate combination with the above heating means, and thus arrived at the present invention. An example of a heating means that irradiates heat rays is an infrared heater, and an example of a heating means that heats the filter material in a high-temperature atmosphere is a gear oven.

The dust collection layer of the present invention uses fine resin powder, the particle size of which can be selected from the range of 0.1 to 200 μm, and preferably uses fine resin powder with an average particle size of 0.1 μm to 50 μm. The average particle size mentioned here refers to the D50 value measured with a particle size distribution measuring device such as a Microtrac.

Examples of fine particles that can be used in place of the PTFE fine particles that make up the dust collection layer according to the technology of the present invention include ultra-high molecular weight polyethylene (GUR2126, manufactured by Celanese Japan) or low molecular weight polyethylene (Hi-Wax HP10A, manufactured by Mitsui Fine Chemicals, Inc.).
In forming the dust-collecting layer, the amount of ultra-high molecular weight polyethylene or low molecular weight polyethylene to be adhered to the surface of the filter element material can be appropriately specified within the range of 1 g to 100 g/ ^m2 , and more preferably, it is adhered in the range of 10 g to 20 g/ ^m2 .
In addition, the particle size of the fine particles constituting the dust collection layer can be selected according to the particle size of the dust to be captured. In other words, when fine particles having a smaller particle size than the particle size of the resin constituting the filter material are used, it becomes possible to capture finer particles.

If the amount of ultra-high molecular weight polyethylene or low molecular weight polyethylene attached to the surface of the filter element material is small, it will not spread throughout and the pores of the sintered body will not be fully filled. If there is too much, it will form lumps on the surface, causing an increase in initial pressure drop.

The easiest way to attach ultra-high molecular weight polyethylene or low molecular weight polyethylene particles to the surface of the filter element material is to apply them with a brush, for example.

3(1) and (2), and the fine particles constituting the dust trapping layer are sucked in by a negative pressure from the side of the filter element laboratory test material that forms the dust trapping layer toward the side of the element material that does not form the dust trapping layer by sucking in the fine particles constituting the dust trapping layer with a brush, thereby making it possible to more densely attach the fine particles constituting the dust trapping layer to the surface of the element material. Also, by blowing air from the side of the element material that does not form the dust trapping layer, it is possible to reduce the density of the fine particles attached to the side of the filter element material that forms the dust trapping layer, and to reduce the initial pressure loss of the dust trapping layer formed by the method of the present invention.
The jig shown in Figures 3(1) and (2) consists of an upper frame 52 having an opening 51 for forming a dust collection layer and a bottom frame 54 equipped with a connecting pipe 53 connected to a suction pump (not shown), and is used by clamping a filter element material 55 between the upper frame 52 and the bottom frame 54 by means of a clamp 56 or the like.

It is also effective to make the particles that make up the dust-collecting layer fly and attract them to the surface of the sintered lamellar filter element material so that they adhere to the surface.
For example, in the two-core integrated element or two-core laminated element (hereinafter referred to as two-core element) described in Examples 4 to 8 and Comparative Example 2 of the present application, a jig shown in Figure 8 is used to form a dust collection layer on the element material.
The jig shown in Figure 8 is composed of a box 81 capable of storing two core element materials 87, a top plate 83 which has an opening corresponding to the opening 90 of the two core elements and covers the upper opening of the box 81, and a suction pipe connection part 86 which connects a suction blower to the opening 83a of the top plate 83, and by interposing a packing 84 at each contact part of the box 81, top plate 83 and suction pipe connection part 86, airtightness is ensured between the core space inside the element which communicates with the suction pipe connection part 86 and the space formed by the outside of the element and the box.
To form a dust collection layer on the surface of the two-core element material 87 using this jig, the two-core element material 87 is pressed and fixed to the top plate 83 so that the core opening 90 and the opening 83a of the top plate 83 are aligned, the top plate 83 is used to close the upper opening of the housing 81 so that the two-core element material 87 is housed in the box 81, and the suction tube connection part 86 is connected to the opening 83a of the top plate. Next, the powder that constitutes the dust collection layer is dispersed and suspended in the space between the outer surface of the two-core element material 87 and the inside of the box 81, and in this state, the blower is operated to form negative pressure from the side of the two-core element material 87 that forms the dust collection layer toward the side that does not form the layer, thereby making it possible to uniformly attach the powder to the surface of the two-core element material 87.
In order to disperse and suspend the powder that forms the dust collection layer in the space between the outer surface of the two core element materials 87 and the inside of the box 81, it is possible to introduce the powder uniformly using a sprayer or the like from powder inlet ports provided in multiple locations on the side wall of the box as in Example 7, or to store the necessary powder in the box in advance and then use a pulse jet or swirling jet, for example, to raise the powder into the space inside the container as in Example 8.
The two-core element material 87 is a filter for a scale-up test of the filter element in the manner shown in FIG. 1, and has a structure including two sets of hollow chambers (cores) with open upper ends inside the filter element, and is an element material obtained by integral sintering or by bonding together the members constituting the element with an adhesive or the like.

The method for forming the dust collection layer from the fine particles attached to the side of the filter element material on which the dust collection layer is to be formed by the above method uses a heating means such as an infrared heater (Figure 2). The side of the filter element material on which the ultra-high molecular weight polyethylene fine particles are attached is heated to near its softening point by the infrared heater, and the resin fine particles are fused together to form the dust collection layer. In this case, if the filter element material on which the ultra-high molecular weight polyethylene fine particles are attached to the side on which the dust collection layer is to be formed is heated while being placed or hung as is, the filter element material will bend, making subsequent mechanical processing extremely difficult.

Therefore, with ultra-high molecular weight polyethylene fine particles attached to the side of the filter element material on which the dust collection layer is to be formed, the filter element is inserted into the metal retainer shown in Figure 4, and while it is laid down, upside down, or hung, infrared rays are irradiated from both the side on which the dust collection layer is to be formed and the side on which the dust collection layer is not to be formed by an infrared heater.
This allows the curvature of the removed filter element to be mechanically restricted to a certain dimension, facilitating subsequent mechanical processing.

In addition, low-molecular-weight polyethylene fine particles with a low softening point are attached as resin fine particles to the side of the filter element material on which the dust collection layer is to be formed, and the filter element is either left as is or inserted into the metal retainer shown in Figure 4 and placed in a fallen, upside-down or suspended position, and infrared rays are irradiated by an infrared heater from the side on which the dust collection layer is to be formed, or from both the side on which the dust collection layer is to be formed and the side on which the dust collection layer is not to be formed.
This allows the curvature of the extracted filter element to be mechanically or physically restricted to a certain dimension, facilitating subsequent mechanical processing.

According to the method of the present invention, a dust-trapping layer is firmly formed on the surface of the filter element material. That is, the resin particles that adhere to the surface of the filter element material and also penetrate into the voids inside the filter element material are fused to the particles that make up the filter element material by infrared irradiation, so that the dust-trapping layer is firmly fused to the filter element material. As a result, the voids in the filter element material are filled with fine polyethylene powder, and the particle shapes of the particles that make up the dust-trapping layer and the particles that make up the filter element material are maintained, so that it is possible to achieve both suppression of initial pressure loss and collection performance.

The dust collection layer formed by the technology of the present invention is more strongly fused to the filter element material than previous technology, making it possible to clean with air blowing or high-pressure running water, and also preventing contamination of the collected dust powder with the fine particles that make up the dust collection layer.

By adjusting the particle size of the ultra-high molecular weight polyethylene that is attached to the surface of the filter element material as the fine particles that make up the dust collection layer, it is possible to adjust the size of the pores in the dust collection layer. It is also possible to change the performance of the dust collection layer by mixing other particles in advance with the ultra-high molecular weight polyethylene particles that are attached.

As a result, the present invention makes it possible to provide users with filters with pore sizes that are sufficient for required performance, such as low pressure loss. Furthermore, it is expected to prevent contamination of collected dust powder, develop new applications, and contribute to improving the efficiency and productivity of dust collector maintenance.

The technology of the present invention makes it possible to simplify the equipment and process for coating the dust-collecting layer, which previously required robots with complex mechanisms and a great deal of manual labor.
The process involves temporarily fixing the element material to the top plate with stays and nuts, sandwiching the packing between them, turning on the blower, and supplying powder, which allows the particles that make up the dust collection layer to adhere evenly to the surface of the element material. The dust collection layer can be formed by removing the element material, placing multiple sheets on a rack, and heating them in an electric drying oven. This reduces the process from the previous four steps of coating solution preparation → coating → drying & waste liquid treatment to just two steps of coating → drying, and also significantly reduces the amount of work per process.
In terms of equipment, coating can be done simply by providing a vinyl enclosure around the device shown in Figure 8, which is made by connecting the blower inlet and top plate, and drying can be done in a general drying oven.
The technology of the present invention uses a simple tool that uses a blower, eliminating the need for robots that are costly to maintain or waste liquid treatment equipment that requires manpower, and simplifying the process.

(1) An external view of a typical dust collector, (2) an external view of a filter element (sinter lamellar), and (3) a perspective view of the P-P cross section. Heating means (infrared heater for laboratory specimens) (1) Plan view of the appearance of the suction jig for laboratory test specimens, (2) Cross-sectional view of the suction jig for laboratory test specimens Retainer Lab Load Test Equipment Heating means (infrared heater for two core elements) Lab Load Test Device for 2 Core Elements (1) Front view of the jig, (2) Front view and side view of the two-core filter element blank attached inside the jig, (3) QQ cross-sectional view of the two-core element blank, (4) Front view and cross-sectional view of the two-core filter element blank attached to the top plate of the jig (1) Adhesion of the powder constituting the dust collection layer to the two-core filter element material inside the jig (condition of Example 7), (2) Adhesion of the powder constituting the dust collection layer to the two-core filter element material inside the jig (condition of Example 8)

The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.
The filter elements used in the examples and comparative examples of the present invention are a laboratory test piece, a two-core integrated element, and a two-core laminated element. The laboratory test piece is a test piece obtained by forming the dust collection layer of the present invention on a plate-shaped element material piece. The two-core integrated element and the two-core laminated element are filter elements for scale-up tests having a structure with two sets of hollow chambers inside the filter element. The two-core integrated element is obtained by forming the dust collection layer of the present invention on an element material obtained by integrally sintering the two-core integrated element. The two-core laminated element is obtained by forming the dust collection layer of the present invention on an element material produced by laminating plate-shaped members constituting the element with an adhesive or the like.

The filter element laboratory test material was placed on the filter element material suction jig (Fig. 3), and 2 g of ultra-high molecular weight polyethylene powder (GUR2126, manufactured by Celanese Japan) was placed on the surface of the laboratory test material. The polyethylene powder was applied with a brush back and forth 10 times while being sucked from the back side of the filter element material suction jig with a vacuum pump at a filtration air speed of 1 m/min., and the polyethylene powder was thoroughly spread into the gaps in the air pores of the laboratory test material.
The laboratory test material coated with the polyethylene powder was inserted into the retainer shown in Fig. 4, and the retainer was then suspended. The irradiating parts of two infrared heaters arranged in the heating means shown in Fig. 2 were placed at a distance of 30 cm from the surface of the retainer, facing the surface of the retainer from both sides of the retainer. Infrared rays were irradiated from the infrared heaters, and when the temperature inside the retainer reached 150°C, the irradiation was stopped and the retainer was gradually cooled to room temperature, completing a laboratory test piece equipped with the dust collection layer of the present invention.

A laboratory test piece with a dust collection layer of the present invention was completed in the same manner as in Example 1, except that the powder placed on the surface of the filter element laboratory test material was 0.5 g of low molecular weight polyethylene (Hi-Wax HP10A, D50 = 45 μm, manufactured by Mitsui Fine Chemicals, Inc.) and the temperature at which infrared radiation from the infrared heater was stopped was set to 110°C.

A laboratory test piece with a dust collection layer of the present invention was completed in the same manner as in Example 2, except that the powder placed on the surface of the filter element laboratory test material was 0.5 g of classified low molecular weight polyethylene (Hi-Wax HP10A, manufactured by Mitsui Fine Chemicals, Inc.) (D50=24 μm).

1.5 g of low molecular weight polyethylene powder (Hi-Wax HP10A, D50=45 μm, manufactured by Mitsui Chemical Fine Co., Ltd.) was placed on the surface of a two-core laminated element material piece, and the low molecular weight polyethylene powder was applied by brushing it back and forth 10 times to ensure that it was thoroughly spread into the gaps of the air pores inside the material piece.
Infrared rays were irradiated from above and below the material piece coated with the low molecular weight polyethylene powder at a distance of 10 cm from two infrared heaters arranged in the heating means shown in Fig. 6. When the temperature of the surface of the material piece coated with the low molecular weight polyethylene powder reached 110°C, the infrared irradiation was stopped and the material piece was allowed to cool to room temperature, thereby producing a two-core laminated element piece provided with a dust-collecting layer of the present invention.
Two of the test laminated element pieces were used and laminated together with an adhesive containing an epoxy resin as a main component to complete a two-core laminated element.

A two-core laminated element was completed in the same manner as in Example 4, except that the powder placed on the surface of the two-core laminated element material piece was 1.5 g of classified low molecular weight polyethylene powder (Hi-Wax HP10A, manufactured by Mitsui Fine Chemicals, Inc.) (D50=24 μm).

The two-core integrated element material 87 was placed in the jig shown in Figure 8, and while sucking at 1.5 m/min using a ring blower connected to the jig by piping, 4 g of classified low molecular weight polyethylene powder (Hiwax HP10A, manufactured by Mitsui Fine Chemicals, Inc.) (D50 = 24 μm) 93 was sprayed from the aerosol outlet 91 in the form shown in Figure 9 (1) and thoroughly spread into the gaps of the pores on the surface of the element. The material was heated for 30 minutes at an atmospheric temperature of 130°C using a gear oven to produce a two-core integrated element equipped with a dust collection layer of the present invention.

Low molecular weight polyethylene powder was sprayed onto the two-core integrated element material 87 in the same manner as in Example 6, and infrared rays were irradiated from a distance of 10 cm from both the top and bottom of the material coated with the low molecular weight polyethylene powder using two infrared heaters arranged in the heating means shown in Figure 6. When the surface temperature of the material coated with the low molecular weight polyethylene powder reached 115°C, the infrared irradiation was stopped and the material was allowed to cool to room temperature, producing a two-core integrated element equipped with a dust collection layer of the present invention.

The two-core integrated element material 87 was placed in the jig shown in Figure 8, and 5 g of classified low molecular weight polyethylene powder (Hiwax HP10A, manufactured by Mitsui Fine Chemicals, Inc.) (D50 = 24 μm) 93 was placed at the bottom of the jig as shown in Figure 9 (2). A ring blower connected to the jig by piping was used to suck at 1.5 m/min, while compressed air was blown in from the compressed air outlet 92 at the bottom of the jig, causing the low molecular weight polyethylene powder 93 to fly up and be sufficiently distributed in the gaps of the air holes on the surface of the element. The material was heated for 30 minutes at an atmospheric temperature of 130°C using a gear oven, and a two-core integrated element equipped with a dust collection layer of the present invention was produced.

[Comparative Example 1]
A coating liquid was prepared by mixing 20.0 wt% ultra-high molecular weight polyethylene powder (GUR2126, manufactured by Celanese Japan Co., Ltd.) with an average particle size of 20 μm, 4.0 wt% copolymer of vinyl acetate and acrylic acid ester (trade name: Movinyl DM5, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as an adhesive, 0.3 wt% mixture of paraffin oil, hydrophobic silica and emulsifier (trade name: Azitan, manufactured by Kusumoto Chemical Industry Co., Ltd.) as an antifoaming agent, and 75.7 wt% water. 4 ml of the coating liquid was placed on the surface of the filter element laboratory test material piece using a syringe, and the material was applied 10 times with a brush. After that, it was dried at 50 ° C for 2 hours, and a laboratory test piece with a dust collection layer composed of polyethylene powder was completed.

[Comparative Example 2]
Two pieces of two-core laminated element material were used and bonded together with an adhesive containing epoxy resin as the main component to prepare a two-core laminated element material.
A coating liquid was prepared by mixing 20.0 wt% ultra-high molecular weight polyethylene powder (GUR2126, Celanese Japan) with an average particle size of 20 μm, 4.0 wt% copolymer of vinyl acetate and acrylic acid ester (trade name: Movinyl DM5, Nippon Synthetic Chemical Industry Co., Ltd.) as an adhesive, 0.3 wt% mixture of paraffin oil, hydrophobic silica and emulsifier (trade name: Azitan, Kusumoto Chemical Industry Co., Ltd.) as an antifoaming agent, and 75.7 wt% water. 20 ml of the coating liquid was placed on the surface of the two-core element material using a syringe and coated with a brush 10 times. After that, it was dried at 50 ° C for 2 hours, and a two-core laminated element with a dust collection layer composed of polyethylene powder was completed.

The test pieces obtained in Examples 1 to 3 and Comparative Example 1 were attached to a Sinter Lamellar Lab dust collection load test device (Fig. 5, manufactured by Nittetsu Mining Co., Ltd.), and a dust collection load confirmation test was performed for 5 minutes under the conditions of a filtration air speed of 6 m/min (processing air volume: 30 L/min) and a dust feed concentration of 10 g/m3, using ^Nittetsu Mining Co., Ltd.'s calcium carbonate powder for flue gas desulfurization (average particle size: 12 μm) as the experimental dust collection powder. In the dust collection load confirmation test, the pressure loss (kPa) at the beginning and end of the test was evaluated.
The test pieces obtained in Examples 1 to 3 and Comparative Example 1 were subjected to an adhesion test (cross-cut method) according to JIS K 5600-5-6: 1999 (ISO 2409: 1992) using a cross cutter (multiple-blade cutter for cross-cut test (checkerboard test) manufactured by Allgood Co., Ltd.).

After the dust collection load confirmation test was completed, a metal ball was dropped from a fixed position at a height of 80 cm onto the test piece, and the weight was measured after it had been shaken off. The difference between this weight and the weight measured beforehand was taken as the amount of invaded powder. The results of this dust collection load confirmation test are shown in Table 1.

The two-core laminated elements obtained in Examples 4 to 5 and Comparative Example 2 were attached to a two-core element laboratory dust collection load test device (Fig. 7, manufactured by Nittetsu Mining Co., Ltd.), and a dust collection load confirmation test was performed for 5 minutes under the conditions of a filtration air speed of 1 m/min (processing air volume: 100 L/min) and a dust feed concentration of 10 g/ ^m3 , using Nittetsu Mining Co., Ltd.'s calcium carbonate powder for flue gas desulfurization (average particle size: 12 μm) as the experimental dust collection powder. In the dust collection load confirmation test, the pressure loss (kPa) at the beginning and end of the test was evaluated.

The two-core integrated elements obtained in Examples 6 to 8 were attached to a two-core element laboratory dust collection load test device (Fig. 7, manufactured by Nittetsu Mining Co., Ltd.), and a dust collection load confirmation test was performed for 5 minutes under the conditions of a filtration air speed of 1 m/min (processing air volume: 160 L/min) and a dust feed concentration of 10 g/ ^m3 , using calcium carbonate powder for flue gas desulfurization (average particle size: 12 μm) manufactured by Nittetsu Mining Co., Ltd. as the experimental dust collection powder. In the dust collection load confirmation test, the pressure loss (kPa) at the beginning and end of the test was evaluated.

After the dust collection load confirmation test was completed, compressed air at a pressure of 4 kg/f was blown from a nozzle with an opening diameter of 5 mm onto the two-core integrated element and the two-core laminated element from a position 50 cm from the test element, and the test powder adhering to the surface of the test element was brushed off and then the weight was measured. The difference with the weight measured beforehand was taken as the amount of invaded powder. The results of this dust collection load confirmation test are shown in Table 2.

The "classification" based on the cross-cut test is as follows:

As is clear from the results of Tables 1 and 2, the initial pressure loss of Example 1 was higher than that of Comparative Example 1, but since the amount of invaded powder was 0.00 g, the pressure loss at the end of the test was close. The cross-cut test revealed that the dust collection layer of the present invention has overwhelming adhesive strength compared to Comparative Example 1.
In particular, in Examples 2 and 3, by using low molecular weight polyethylene with a lower softening point for the fine particles that make up the dust trap compared to Example 1, deformation of the filter element material due to heating can be suppressed, making it possible to apply the filter element to a lamellar filter element.
Moreover, in Example 4, which used a two-core laminated element with a larger test piece compared to the laboratory test piece, the initial pressure loss was lower but the amount of invaded powder was slightly increased compared to Comparative Example 2. In Example 5, which used particles with a smaller particle size compared to Example 4 for the fine particles constituting the dust collection layer, a dust collection layer with lower initial pressure loss and less invaded powder compared to Comparative Example 2 could be formed.
Although the dust collection layers formed in Examples 4, 5, and 6 to 8 were not subjected to a cross-cut test, since they have the same components as those in Examples 2 and 3, it goes without saying that they have adhesive strength to the element material.

REFERENCE SIGNS LIST 10 Sinter lamellar dust collector 12 Casing 14 Upper top plate 16 Dust collection chamber 18 Clean air chamber 20 Dust-containing air supply port 22 Clean air discharge port 24 Filter element 24a Hollow chamber 26 Hopper 28 Dust removal port 32 Large diameter portion 34 Frame 36 Fastening bolt 38 Gasket 51 Opening 52 Upper frame 53 Connection pipe 54 Bottom frame 55 Filter element laboratory test material 56 Clamp 81 Box body 82 Powder introduction portion 83 Top plate 83a Opening in top plate 84 Gasket 85 Flange 86 Suction pipe connection portion 87 Two-core filter element material 88 Two-core filter element material fixing stay 89 Two-core filter element material fixing nut 90 Two-core filter element material hollow chamber 91 Aerosol outlet 92 Compressed air outlet 93 Powder constituting the dust collection layer

Claims (4)

a filter element manufacturing method comprising: forming a layer of binder-free resin fine particles that constitutes a dust collection layer on the surface of a filter element material made of a resin sintered body by depositing the resin fine particles on the surface of the filter element material made of the resin sintered body while sucking the filter element material made of the resin sintered body; heating the layer of resin fine particles by heating means that irradiates heat rays and also heating the back surface of the filter material; or heating the entire filter material on which the dust collection layer has been formed to a temperature near the softening point of the resin fine particles by heating means that heats the entire filter material in a high-temperature atmosphere, such as an oven, to a temperature near the softening point of the resin fine particles, stopping the heating when the temperature near the softening point is reached, and slowly cooling the filter material to room temperature , thereby sintering the resin fine particles and forming the dust collection layer. The method for manufacturing a filter element according to claim 1, which is a resin powder characterized in that the particle size of the resin particles constituting the dust collection layer is smaller than that of the resin constituting the filter element material. The method for manufacturing a filter element according to claim 1 or 2, wherein the resin powder is characterized in that the softening point of the resin particles constituting the dust collection layer is lower than that of the resin constituting the filter element material. The method for manufacturing a filter element according to any one of claims 1 to 3, wherein the heating means for irradiating heat rays is an infrared heater.

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